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[[File:GenIVRoadmap-en.svg|thumb|480px|Nuclear Energy Systems Deployable no later than 2030 and offering significant advances in sustainability, safety and reliability, and economics]]

'''Generation IV reactors''' ('''Gen IV''') are a set of [[nuclear reactor]] designs currently being researched for commercial applications by the Generation IV International Forum, with [[Technology readiness level]]s varying between the level requiring a demonstration, to economical competitive implementation.<ref name=Locatelli>{{Cite journal|last=Locatelli|first=Giorgio|last2=Mancini|first2=Mauro|last3=Todeschini|first3=Nicola|date=2013-10-01|title=Generation IV nuclear reactors: Current status and future prospects|journal=Energy Policy|volume=61|pages=1503–1520|doi=10.1016/j.enpol.2013.06.101}}</ref> They are motivated by a variety of goals including improved safety, sustainability, efficiency, and cost.

The most developed Gen IV reactor design, the [[sodium fast reactor]], has received the greatest share of funding over the years with a number of demonstration facilities operated, the principle Gen IV aspect of the design, relates in largest part to the development of a sustainable closed [[Nuclear_fuel_cycle#Plutonium_cycle|fuel cycle]] for the reactor. Amongst nuclear engineers the [[molten-salt reactor]], the least developed and funded technology, is considered as potentially having the greatest [[Passive nuclear safety|inherent safety]] of the six models.<ref>{{cite web|url=https://www.scientificamerican.com/article/can-sodium-save-nuclear-power/|title=Can Sodium Save Nuclear Power?|publisher=}}</ref><ref>{{cite journal |last1=Moir |first1=Ralph |last2=Teller |first2=Edward |year=2005 |title=Thorium-Fueled Underground Power Plant Based on Molten Salt Technology |journal=Nuclear Technology |volume=151 |issue=3 |pages=334–340 |url=http://www.new.ans.org/pubs/journals/nt/a_3655 |accessdate=March 22, 2012 }}</ref> While the [[hydrogen economy]], the [[high temperature electrolysis|thermochemical production]] of hydrogen to synthesize [[Carbon-neutral fuel]]s, is deemed as strengthening the economic case for the two most efficient models, the [[Very-high-temperature reactor|high temperature reactor]] designs.<ref name=Locatelli/>

The majority of the 6 designs are generally not expected to be available for commercial construction until 2020–30.<ref name="Generation IV">{{cite web|url=http://www.world-nuclear.org/info/Nuclear-Fuel-Cycle/Power-Reactors/Generation-IV-Nuclear-Reactors/|title=Generation IV Nuclear Reactors: WNA - World Nuclear Association|website=www.world-nuclear.org}}</ref> Presently the majority of reactors in operation around the world are considered [[Generation II reactor|second generation reactor]] systems, as the vast majority of the [[Nuclear reactor#Classification by generation|first generation]] systems were retired some time ago, and there are only a dozen or so [[Generation III reactor]]s in operation as of 2014.
[[Nuclear reactor#Generation V+ reactors|Generation V reactors]] refer to reactors that are purely theoretical and are therefore not yet considered feasible in the short term, resulting in limited [[R&D]] funding.

== History ==
The Generation IV International Forum (GIF) is "a co-operative international endeavour which was set up to carry out the research and development needed to establish the feasibility and performance capabilities of the next generation nuclear energy systems."<ref>{{Cite web|url=https://www.gen-4.org/gif/jcms/c_9260/public|title=GIF Portal - Home - Public|website=www.gen-4.org|access-date=2016-07-25}}</ref> It was founded in 2001. Currently active members of the Generation IV International Forum (GIF) include: [[Australia]], [[Canada]], [[China]], the [[European Atomic Energy Community]] (Euratom), [[France]], [[Japan]], [[Russia]], [[South Africa]], [[South Korea]], [[Switzerland]], and the [[United States]]. The non-active members are [[Argentina]], [[Brazil]], and the [[United Kingdom]].<ref name="gen-4">{{cite web|url=https://www.gen-4.org/gif/jcms/c_9492/members|title=GIF Membership|website=gen-4.org|accessdate=28 October 2014}}</ref> Switzerland joined in 2002, Euratom in 2003, and China and Russia in 2006. The remaining countries (excluding Australia) were founding members.<ref name="gen-4" />

The 36th GIF meeting in [[Brussels]] was held in November 2013.<ref>{{cite web|url=https://www.energy.gov/ne/articles/generation-iv-international-forum-updates-technology-roadmap-and-builds-future|title=generation IV international forum updates technology roadmap and builds future. DOE}}</ref><ref>{{cite web|url=http://events.r20.constantcontact.com/register/event?llr=mscrkjkab&oeidk=a07e7melf609716b2c6 |title=The Generation IV international forum holds their 36th meeting on Monday 18th Nov 2013 in Brussels }}{{dead link|date=January 2017 |bot=InternetArchiveBot |fix-attempted=yes }}</ref> The ''Technology Roadmap Update for Generation IV Nuclear Energy Systems'' was published in January 2014 which details R&D objectives for the next decade.<ref>{{cite web|url=https://www.gen-4.org/gif/upload/docs/application/pdf/2014-03/gif-tru2014.pdf|archive-url=https://web.archive.org/web/20140625102915/https://www.gen-4.org/gif/upload/docs/application/pdf/2014-03/gif-tru2014.pdf|dead-url=yes|archive-date=25 June 2014|title=Wayback Machine|date=25 June 2014|publisher=}}</ref> A breakdown of the reactor designs being researched by each forum member has been made available.<ref>{{cite web|url=https://www.gen-4.org/gif/upload/docs/application/pdf/2014-03/gif_overview_presentation_v9_final3_web.pdf|archive-url=https://web.archive.org/web/20140708023538/https://www.gen-4.org/gif/upload/docs/application/pdf/2014-03/gif_overview_presentation_v9_final3_web.pdf|dead-url=yes|archive-date=8 July 2014|title=Wayback Machine|date=8 July 2014|publisher=}}</ref>

[[Nuclear power in Australia|Australia]] joined the forum in 2016.<ref>{{cite web|url=https://www.gen-4.org/gif/jcms/c_71564/australia-joins-the-generation-iv-international-forum|archiveurl=https://archive.today/20160907131656/https://www.gen-4.org/gif/jcms/c_71564/australia-joins-the-generation-iv-international-forum|deadurl=yes|title=GIF Portal - Australia joins the Generation IV International Forum|date=7 September 2016|archivedate=7 September 2016|publisher=}}</ref>

In January 2018, it was reported that "the first installation of the pressure vessel cover of the world's first Gen IV reactor" had been completed on the [[HTR-PM]].<ref>{{cite web|url=http://www.world-nuclear-news.org/NN-First-HTR-PM-vessel-head-in-place-0401185.html|title=First HTR-PM vessel head in place - World Nuclear News|website=www.world-nuclear-news.org}}</ref>

== Reactor types ==
Many reactor types were considered initially; however, the list was downsized to focus on the most promising technologies and those that could most likely meet the goals of the Gen IV initiative.<ref name="Generation IV"/> Three systems are nominally [[thermal reactor]]s and four are [[fast reactor]]s. The Very High Temperature Reactor (VHTR) is also being researched for potentially providing high quality process heat for [[thermochemical cycle|hydrogen production]]. The fast reactors offer the possibility of burning [[actinides]] to further reduce waste and of being able to "[[breeder reactor|breed more fuel]]" than they consume. These systems offer significant advances in sustainability, safety and reliability, economics, proliferation resistance (depending on perspective) and physical protection.

=== Thermal reactors ===
A [[Thermal-neutron reactor|thermal reactor]] is a [[nuclear reactor]] that uses slow or [[thermal neutrons]]. A [[neutron moderator]] is used to slow the [[neutron]]s emitted by fission to make them more likely to be captured by the fuel.

==== Very-high-temperature reactor (VHTR) ====
[[File:Very High Temperature Reactor.svg|right|thumb|Very-High-Temperature Reactor (VHTR)]]
{{Main article|Very high temperature reactor}}
{{see also|Fort St. Vrain Generating Station|High-temperature engineering test reactor|HTR-10}}
The '''very high temperature reactor''' concept uses a [[graphite]]-moderated core with a once-through [[uranium]] fuel cycle, using helium or molten salt as the [[Very high temperature reactor#Coolant|coolant]]. This reactor design envisions an outlet temperature of 1,000 °C. The reactor core can be either a prismatic-block or a [[pebble bed reactor]] design. The high temperatures enable applications such as process heat or [[hydrogen]] production via the thermochemical [[Sulfur-iodine cycle|iodine-sulfur]] process. It would also be [[Passive nuclear safety|passively safe]].

The planned construction of the first VHTR, the South African PBMR ([[pebble bed modular reactor]]), lost government funding in February, 2010.<ref>[http://www.powergenworldwide.com/index/display/articledisplay/6322207443/articles/power-engineering-international/volume-18/Issue_3/regulars/world-news/INTERNATIONAL.html South Africa to stop funding Pebble Bed nuclear reactor] {{webarchive|url=https://web.archive.org/web/20100909172743/http://www.powergenworldwide.com/index/display/articledisplay/6322207443/articles/power-engineering-international/volume-18/Issue_3/regulars/world-news/INTERNATIONAL.html |date=2010-09-09 }}</ref> A pronounced increase of costs and concerns about possible unexpected technical problems had discouraged potential investors and customers.

The [[People's Republic of China]] began construction of a 200-MW High Temperature Pebble bed reactor in 2012 as a successor to its [[HTR-10]].<ref>{{cite web|url=http://www.nucnet.org/all-the-news/2013/01/07/china-begins-construction-of-first-generation-iv-htr-pm-unit|title=China Begins Construction Of First Generation IV HTR-PM Unit|first=Central Office, NucNet a.s.b.l., Brussels,|last=Belgium|website=www.nucnet.org}}</ref>

Also in 2012, as part of the [[Next Generation Nuclear Plant]] competition, [[Idaho National Laboratory]] approved a design similar to [[Areva]]'s prismatic block [https://web.archive.org/web/20150722041246/http://us.areva.com/EN/home-3225/areva-inc-areva-htgr.html Antares reactor] as the chosen [[HTGR]] to be deployed as a prototype by 2021. It was in competition with [[General Atomics]]' [[Gas turbine modular helium reactor]] and [[Westinghouse Electric Company|Westinghouse]]'s [[Pebble Bed Modular Reactor]].<ref name="World nuclear news">{{cite web|url=http://www.world-nuclear-news.org/NN-Areva_modular_reactor_selected_for_NGNP_development-1502124.html|title=INL approves Antares design}}</ref>

[[X-energy]] was awarded a five-year $53M U.S. Department of Energy Advanced Reactor Concept Cooperative Agreement award to advance elements of their reactor development.<ref>{{cite web|url=https://www.x-energy.com/doe-partnership|title=x-energy - DOE Partnership|website=x-energy}}</ref>
The [[X-energy#Reactor Design|Xe-100]] is a pebble-bed modular reactor and will generate 200-MWt and approximately 76-MWe. The standard Xe-100 "four-pack" plant generates approximately 300-MWe and will fit on as few as 13 acres. All of the components for the Xe-100 will be road-transportable, and will be installed, rather than constructed, at the project site to streamline construction.<ref name="X-energy">{{cite web|url=https://www.x-energy.com/|title=x-energy|website=x-energy}}</ref>

==== Molten-salt reactor (MSR) ====
[[File:Molten Salt Reactor.svg|right|thumb|Molten Salt Reactor (MSR)]]
{{Main article|Molten salt reactor}}
{{see also|Liquid fluoride thorium reactor}}
A '''molten salt reactor'''<ref name="Roadmap"/> is a type of [[nuclear reactor]] where the primary [[coolant]], or even the fuel itself is a molten salt mixture. There have been many designs put forward for this type of reactor and a few prototypes built. The early concepts and many current ones rely on [[nuclear fuel]], perhaps [[uranium tetrafluoride]] (UF4) or [[thorium tetrafluoride]] (ThF4), dissolved in molten [[fluoride]] salt. The fluid would reach [[Nuclear reactor physics#Criticality|criticality]] by flowing into a core where [[graphite]] would serve as the [[neutron moderator|moderator]]. Many current concepts rely on fuel that is dispersed in a graphite matrix with the molten salt providing low pressure, high temperature cooling.

The Gen IV MSR is more accurately termed an [[epithermal neutron|epithermal reactor]] than a thermal reactor due to the average speed of the neutrons that would cause the fission events within its fuel being faster than [[thermal neutron]]s.<ref>{{cite web |url=https://inlportal.inl.gov/portal/server.pt?open=514&objID=1361&parentname=CommunityPage&parentid=10&mode=2&in_hi_userid=200&cached=true |title=Idaho National Laboratory detailing some current efforts at developing Gen. IV reactors}}</ref>

The principle of a MSR can be used for thermal, epithermal and fast reactors. Since 2005 the focus has moved towards a fast spectrum MSR (MSFR).<ref>H. Boussier, S. Delpech, V. Ghetta et Al. : The Molten Salt Reactor (MSR) in Generation IV: Overview and Perspectives, GIF SYMPOSIUM PROCEEDINGS/2012 ANNUAL REPORT, NEA No. 7141, pp95 [https://www.gen-4.org/gif/jcms/c_44720/annual-reports]
</ref>

While most MSR designs being pursued are largely derived from the 1960s [[Molten-Salt Reactor Experiment]] (MSRE), variants of molten salt technology include the conceptual ''[[Dual fluid reactor]]'' which is being designed with lead as a cooling medium but molten salt fuel, commonly as the metal chloride e.g. [[Plutonium(III) chloride]], to aid in greater "nuclear waste" closed-fuel cycle capabilities.
Other notable approaches differing substantially from MSRE include the ''[[Stable Salt Reactor]]'' (SSR) concept promoted by MOLTEX, which encases the molten salt in hundreds of the common solid [[fuel rod]]s that are already well established in the nuclear industry. This latter British design was found to be the most competitive for [[Small modular reactor]] development by a British-based consultancy firm ''Energy Process Development'' in 2015.<ref>{{cite web|url=http://www.daretothink.org/europe-moltex-stable-salt-reactor/|title=Europe: Moltex' Stable Salt Reactor|date=20 April 2015|publisher=}}</ref><ref>{{cite web|url=http://analysis.nuclearenergyinsider.com/moltex-energy-sees-uk-canada-smr-licensing-springboard-asia|title=Moltex Energy sees UK, Canada SMR licensing as springboard to Asia - Nuclear Energy Insider|website=analysis.nuclearenergyinsider.com}}</ref>

Another notable feature of the MSR is the possibility of a [[Thermal-neutron reactor|thermal spectrum]] nuclear [[Nuclear fuel cycle#Fuel cycles|waste-burner]]. Conventionally only fast spectrum reactors have been considered viable for [[Nuclear fuel cycle#Minor actinides recycling|utilization or reduction]] of the [[Spent nuclear fuel|spent nuclear stockpiles]]. The conceptual viability of a thermal waste-burner was first shown in a whitepaper by [[Seaborg Technologies]] spring 2015.<ref name="Seaborg Whitepaper 2015">{{cite web|url=https://seaborg.dk/s/Seaborg-whitepaper-2015.pdf|title=Thermal MSR waste burner benchmark}}</ref> Thermal waste-burning was achieved by replacing a fraction of the [[uranium]] in the spent nuclear fuel with [[thorium]]. The net production rate of [[transuranium element]] (e.g. [[plutonium]] and [[americium]]) is reduced below the consumption rate, thus reducing the magnitude of the [[Radioactive waste|nuclear storage problem]], without the [[nuclear proliferation]] concerns and other [[Fast-neutron reactor#Disadvantages|technical issues]] associated with a [[Fast-neutron reactor|fast reactor]].

==== Supercritical-water-cooled reactor (SCWR) ====
[[File:Supercritical-Water-Cooled Reactor.svg|right|thumb|Supercritical-Water-Cooled Reactor (SCWR)]]
{{Main article|Supercritical water reactor}}
The '''supercritical water reactor''' (SCWR)<ref name="Roadmap"/> is a [[reduced moderation water reactor]] concept that, due to the average speed of the neutrons that would cause the fission events within the fuel being faster than [[thermal neutron]]s, it is more accurately termed an [[epithermal neutron|epithermal reactor]] than a thermal reactor. It uses [[supercritical fluid|supercritical water]] as the working fluid. SCWRs are basically [[light water reactor]]s (LWR) operating at higher pressure and temperatures with a direct, once-through heat exchange cycle. As most commonly envisioned, it would operate on a direct cycle, much like a boiling water reactor ([[BWR]]), but since it uses supercritical water (not to be confused with [[Critical mass (nuclear)|critical mass]]) as the working fluid, it would have only one water phase present, which makes the supercritical heat exchange method more similar to a pressurized water reactor ([[Pressurized water reactor|PWR]]). It could operate at much higher temperatures than both current PWRs and BWRs.

Supercritical water-cooled reactors (SCWRs) are promising advanced nuclear systems because of their high [[thermal efficiency]] (i.e., about 45% vs. about 33% efficiency for current LWRs) and considerable plant simplification.

The main mission of the SCWR is generation of low-cost [[electricity]]. It is built upon two proven technologies, LWRs, which are the most commonly deployed power generating reactors in the world, and superheated [[fossil fuel]] fired [[boiler]]s, a large number of which are also in use around the world. The SCWR concept is being investigated by 32 organizations in 13 countries.{{citation needed|date=October 2012}}

Because SCWRs are water reactors they share the steam explosion and radioactive steam release hazards of BWRs and LWRs as well as the need for extremely expensive heavy duty pressure vessels, pipes, valves, and pumps. These shared problems are inherently more severe for SCWRs due to operation at higher temperatures.

A SCWR Design under development is the [[VVER]]-1700/393 (VVER-SCWR or VVER-SKD) — a Russian Supercritical-water-cooled reactor with double-inlet-core and a [[breeder reactor|breeding ratio]] of 0.95.<ref name="powertecrussia.com">{{cite web |url=http://www.powertecrussia.com/blog/tag/nuclear-power/ |title=Technology Developments & Plant Efficiency for the Russian Nuclear Power Generation Market Wednesday |date=March 24, 2010}}</ref>

=== Fast reactors ===
A [[Fast-neutron reactor|fast reactor]] directly uses the fast neutrons emitted by fission, without moderation. Unlike thermal neutron reactors, fast neutron reactors can be configured to "'''burn'''", or fission, all [[actinides]], and given enough time, therefore drastically reduce the actinides fraction in [[spent nuclear fuel]] produced by the present world fleet of thermal neutron [[light water reactor]]s, thus closing the [[nuclear fuel cycle]]. Alternatively, if configured differently, they can also [[breeder reactor|'''breed''']] more actinide fuel than they consume.

==== Gas-cooled fast reactor (GFR) ====
[[File:Gas-Cooled Fast Reactor Schemata.svg|right|thumb|Gas-Cooled Fast Reactor (GFR)]]
{{Main article|Gas-cooled fast reactor}}
The '''gas-cooled fast reactor''' (GFR)<ref name="Roadmap"/> system features a fast-neutron spectrum and closed fuel cycle for efficient conversion of [[Fertile material|fertile uranium]] and management of actinides. The reactor is [[helium]]-cooled and with an outlet temperature of 850 °C it is an evolution of the [[very-high-temperature reactor]] (VHTR) to a more sustainable fuel cycle. It will use a direct [[Brayton cycle]] [[Closed-cycle gas turbine|gas turbine]] for high thermal efficiency. Several fuel forms are being considered for their potential to operate at very high temperatures and to ensure an excellent retention of [[Nuclear fission|fission]] products: composite [[ceramic]] fuel, advanced fuel particles, or ceramic clad elements of actinide compounds. Core configurations are being considered based on pin- or plate-based fuel assemblies or prismatic blocks.

The European Sustainable Nuclear Industrial Initiative is funding three Generation IV reactor systems, one of which is a gas-cooled fast reactor, called ''Allegro'', 100 MW(t), which will be built in a central or eastern European country with construction expected to begin in 2018.<ref name="euronuclear.org">{{cite web|url=https://www.euronuclear.org/1-information/news/Gen-IV.htm |title=The European Sustainable Nuclear Industrial Initiative (ESNII) will support three Generation IV reactor systems: a sodium-cooled fast reactor, or SFR, called ''Astrid'' that is proposed by France; a gas-cooled fast reactor, GFR, called ''Allegro'' supported by central and eastern Europe; and a lead-cooled fast reactor, LFR, technology pilot called ''Myrrha'' that is proposed by Belgium |deadurl=yes |archiveurl=https://web.archive.org/web/20131009042600/http://euronuclear.org/1-information/news/Gen-IV.htm |archivedate=2013-10-09 |df= }}</ref> The central European [[Visegrád Group]] are committed to pursuing the technology.<ref>{{cite web |url=http://www.alphagalileo.org/ViewItem.aspx?ItemId=133111&CultureCode=en |title=The V4G4 Centre of Excellence for performing joint research, development and innovation in the field of Generation-4 (G4) nuclear reactors have been established. 20 July 2013 National Center for Nuclear Research (NCBJ)}}</ref> In 2013 German, British, and French institutes finished a 3-year collaboration study on the follow on industrial scale design, known as ''GoFastR''.<ref>{{cite web|url=http://www.ist-world.org/ProjectDetails.aspx?ProjectId=5cb8f3f283574cc6b2bdbf72533172d8 |title=the European Gas cooled Fast Reactor |deadurl=yes |archiveurl=https://web.archive.org/web/20131213091046/http://www.ist-world.org/ProjectDetails.aspx?ProjectId=5cb8f3f283574cc6b2bdbf72533172d8 |archivedate=2013-12-13 |df= }}</ref> They were funded by the EU's 7th FWP [[framework programme]], with the goal of making a sustainable VHTR.<ref>{{cite web |url=http://www.2020-horizon.com/GOFASTR-European-Gas-Cooled-Fast-Reactor%28GOFASTR%29-s312.html |title=The GOFASTR research program}}</ref>

==== Sodium-cooled fast reactor (SFR) ====
[[File:Sodium-Cooled Fast Reactor Schemata.svg|right|thumb|Pool design Sodium-Cooled Fast Reactor (SFR)]]
{{Main article|Sodium-cooled fast reactor}}
{{see also|Experimental Breeder Reactor II|S-PRISM|Toshiba 4S|CFR-600}}

The two largest commercial sodium cooled fast reactors are both in Russia, the [[BN-600]] and the recently completed [[BN-800]](800 MW). The largest ever operated was the [[Superphenix]] reactor at over 1200 MW of electrical output, successfully operating for a number of years in France before being decommissioned in 1996. In India, the [[Fast Breeder Test Reactor]] reached criticality in October 1985. In September 2002, fuel [[burnup|burn up]] efficiency in the FBTR for the first time reached the 100,000 megawatt-days per metric ton uranium (MWd/MTU) mark. This is considered an important milestone in Indian breeder reactor technology. Using the experience gained from the operation of the FBTR, the [[Prototype Fast Breeder Reactor]], a 500 MWe Sodium cooled fast reactor is being built at a cost of INR 5,677 crores (~US$900 million) and is expected to be critical by June 2019. The PFBR will be followed by six more Commercial Fast Breeder Reactors (CFBRs) of 600 MWe each.

The Gen IV SFR<ref name="Roadmap"/> is a project that builds on two closely related existing projects, the liquid metal [[Breeder reactor#Fast breeder reactor|fast breeder reactor]] and the [[integral fast reactor]].

The goals are to increase the efficiency of uranium usage by [[breeder reactor|breeding]] plutonium and eliminating the need for [[transuranic]] isotopes ever to leave the site. The reactor design uses an unmoderated core running on [[fast neutron]]s, designed to allow any transuranic isotope to be consumed (and in some cases used as fuel). In addition to the benefits of removing the long [[half-life]] transuranics from the waste cycle, the SFR fuel expands when the reactor overheats, and the chain reaction automatically slows down. In this manner, it is passively safe.<ref>{{cite web |url=http://www.ne.anl.gov/About/hn/logos-winter02-psr.shtml|title=Passively safe reactors rely on nature to keep them cool|author=David Baurac}}</ref>

The SFR reactor concept is cooled by liquid [[sodium]] and fueled by a metallic alloy of uranium and [[plutonium]] or [[spent nuclear fuel]], the "nuclear waste" of [[light water reactor]]s. The SFR fuel is contained in steel cladding with liquid sodium filling in the space between the clad elements which make up the fuel assembly. One of the design challenges of an SFR is the risks of handling sodium, which reacts explosively if it comes into contact with water. However, the use of liquid metal instead of water as coolant allows the system to work at atmospheric pressure, reducing the risk of leakage.

[[File:Ifr concept.jpg|thumb|375px|The sustainable fuel-cycle proposed in the 1990s [[Integral fast reactor]] concept (color), an animation of the [[pyroprocessing]] technology is also available.<ref>{{cite web |url=https://www.youtube.com/watch?v=cBThTwFhRlA |title=Historical video about the Integral Fast Reactor (IFR) concept. Uploaded by - Nuclear Engineering at Argonne}}</ref>]]
[[File:IFR concept.png|thumb|375px|IFR concept (Black and White with clearer text)]]

The European Sustainable Nuclear Industrial Initiative is funding three Generation IV reactor systems, one of which is a sodium-cooled fast reactor, called ''[[ASTRID (reactor)|ASTRID]]'', Advanced Sodium Technical Reactor for Industrial Demonstration, [[Areva]], [[Commissariat à l'énergie atomique et aux énergies alternatives|CEA]] and [[Électricité de France|EDF]] are leading the design with British collaboration.<ref>{{cite web |url=http://www.power-eng.com/articles/2010/11/areva--cea-secure.html |title=Areva, CEA secure EUR650m funding to develop ASTRID sodium-cooled Generation IV reactor 11/11/2010}}</ref><ref>{{cite web |url=http://www.powermag.com/uk-and-france-sign-landmark-civil-nuclear-cooperation-agreement/ |title=UK and France Sign Landmark Civil Nuclear Cooperation Agreement 02/22/2012 . POWERnews}}</ref> Astrid will be rated about 600 MWe and is proposed to be built in France, near to the [[Phénix]] reactor. A final decision in construction is to be made in 2019<ref name="euronuclear.org"/>

The [[China|PRC]]'s first commercial-scale, 800 MWe, fast neutron reactor, to be situated near [[Sanming]] in [[Fujian province]] will be a SFR. In 2009 an agreement was signed that would entail the Russian [[BN-800 reactor]] design to be sold to the PRC once it is completed, this would be the first time commercial-scale fast neutron reactors have ever been exported.<ref>{{cite web |url=http://www.world-nuclear-news.org/C-Joint_venture_launched_for_Chinese_fast_reactor-3004104.html |title=Joint venture launched for Chinese fast reactor}}</ref> The BN-800 reactor became operational in 2014.

Numerous progenitors of the Gen IV SFR exist around the world, with the 400 MWe [[Fast Flux Test Facility]] operated successfully for ten years at the Hanford site in Washington State.

The 20 MWe [[EBR II]] operated successfully for over thirty years at the Idaho National Laboratory, until it was shut down in 1994.

GE Hitachi's [[PRISM (reactor)|PRISM]] reactor is a modernized and commercial implementation of the technology developed for the Integral Fast Reactor(IFR), developed by [[Argonne National Laboratory]] between 1984 and 1994. With the primary purpose of PRISM differing in the focus on burning up [[spent nuclear fuel]] from other reactors, rather than [[breeder reactor|breeding]] new fuel. Presented as an alternative to burying the spent fuel/waste, the design reduces the half lives of the fissionable elements present in spent nuclear fuel while generating electricity largely as a by-product.

==== Lead-cooled fast reactor (LFR) ====
[[File:Lead-Cooled Fast Reactor Schemata.svg|right|thumb|Lead-Cooled Fast Reactor (LFR)]]
{{Main article|Lead-cooled fast reactor}}
{{See also|MYRRHA}}
The '''lead-cooled fast reactor'''<ref name="Roadmap">{{cite journal|year=2002 |title=A Technology Roadmap for Generation IV Nuclear Energy Systems |last=US DOE Nuclear Energy Research Advisory Committee |volume=GIF-002-00 |url=http://nuclear.energy.gov/genIV/documents/gen_iv_roadmap.pdf |deadurl=yes |archiveurl=https://web.archive.org/web/20071129121214/http://nuclear.energy.gov/genIV/documents/gen_iv_roadmap.pdf |archivedate=2007-11-29 |df= }}</ref> features a fast-neutron-spectrum [[lead]] or [[lead]]/[[bismuth]] [[eutectic]] ([[Lead-bismuth eutectic|LBE]]) liquid-metal-cooled reactor with a closed [[Nuclear fuel cycle|fuel cycle]]. Options include a range of plant ratings, including a "battery" of 50 to 150 MW of electricity that features a very long refueling interval, a modular system rated at 300 to 400 MW, and a large monolithic plant option at 1,200 MW (The term ''battery'' refers to the long-life, factory-fabricated core, not to any provision for electrochemical energy conversion). The fuel is metal or nitride-based containing [[Fertile material|fertile uranium]] and [[transuranic]]s. The LFR is cooled by natural [[convection]] with a reactor outlet coolant temperature of 550 °C, possibly ranging up to 800 °C with advanced materials. The higher temperature enables the production of [[Thermochemical cycle|hydrogen by thermochemical processes]].

The European Sustainable Nuclear Industrial Initiative is funding three Generation IV reactor systems, one of which is a lead-cooled fast reactor that is also an [[Subcritical reactor|accelerator-driven sub-critical]] reactor, called ''[[MYRRHA]]'', 100 MW(t), which will be built in [[Belgium]] with construction expected to begin after 2014 and the industrial scale version, known as ''Alfred'', slated to be constructed sometime after 2017. A reduced-power model of Myrrha called ''Guinevere'' was started up at [[Mol, Belgium|Mol]] in March 2009.<ref name="euronuclear.org"/> In 2012 the research team reported that Guinevere was operational.<ref>{{cite news|last1=Hellemans|first1=Alexander|title=Reactor-Accelerator Hybrid Achieves Successful Test Run|url=http://news.sciencemag.org/physics/2012/01/reactor-accelerator-hybrid-achieves-successful-test-run|accessdate=29 December 2014|work=Science Insider|date=12 January 2012}}</ref>

Two other lead-cooled fast reactors under development are the SVBR-100, a modular 100 MWe lead-bismuth cooled fast neutron reactor concept designed by OKB [[Gidropress]] in Russia and the [[BREST (Reactor)|BREST-OD-300]] (Lead-cooled fast reactor) 300 MWe, to be developed after the SVBR-100, and built over 2016-20, it will dispense with the [[Uranium-238|fertile blanket]] around the core and will supersede the sodium cooled [[BN-600 reactor]] design, to purportedly give enhanced proliferation resistance.<ref name="powertecrussia.com"/>

== Advantages and disadvantages ==
Relative to current nuclear power plant technology, the claimed benefits for 4th generation reactors include:
* Nuclear waste that remains radioactive for a few centuries instead of millennia<ref>{{cite web |title=Strategies to Address Global Warming |url=http://www.columbia.edu/~jeh1/mailings/2009/20090713_Strategies.pdf}}</ref>
* 100–300 times more energy yield from the same amount of nuclear fuel<ref>{{cite web |title=4th Generation Nuclear Power |url=http://www.ossfoundation.us/projects/energy/nuclear}}</ref>
* Broader range of fuels, and even unencapsulated raw fuels (non-pebble [[Molten Salt Reactor|MSR]], [[Liquid fluoride thorium reactor|LFTR]]).
* In some reactors, the ability to consume existing nuclear waste in the production of electricity, that is, a Closed [[nuclear fuel cycle]]. This strengthens the argument to deem [[nuclear power as renewable energy]].
* Improved operating safety features, such as (depending on design) avoidance of pressurized operation, automatic passive (unpowered, uncommanded) reactor shutdown, avoidance of water cooling and the associated risks of loss of water (leaks or boiling) and hydrogen generation/explosion and contamination of coolant water.

Nuclear reactors do not emit CO2 during operation, although like all [[low carbon power]] sources, the mining and construction phase can result in CO2 emissions, if energy sources which are not carbon neutral (such as fossil fuels), or CO2 emitting cements are used during the construction process.
A 2012 [[Yale University]] review published in the Journal of Industrial Ecology analyzing {{CO2}} [[life cycle assessment]] (LCA) emissions from [[nuclear power]] determined that:<ref name="Warner + Heath, JoIE">{{cite journal |doi=10.1111/j.1530-9290.2012.00472.x|title=Life Cycle Greenhouse Gas Emissions of Nuclear Electricity Generation|journal=Journal of Industrial Ecology|volume=16|pages=S73–S92|year=2012|last1=Warner|first1=Ethan S|last2=Heath|first2=Garvin A}}</ref>
{{Quote|The collective LCA literature indicates that life cycle [[Greenhouse gas|GHG]] [greenhouse gas] emissions from nuclear power are only a fraction of traditional fossil sources and comparable to renewable technologies.}}
Although the paper primarily dealt with data from [[Generation II reactor]]s, and did not analyze the {{CO2}} emissions by 2050 of the presently under construction [[Generation III reactor]]s, it did summarize the Life Cycle Assessment findings of in development reactor technologies.{{Quote|FBRs ['[[Fast Breeder Reactor]]s'] have been evaluated in the LCA literature. The limited literature that evaluates this potential future technology reports [[median]] life cycle GHG emissions... similar to or lower than LWRs [Gen II [[light water reactor]]s] and purports to consume little or no [[uranium market|uranium ore]].}}

A specific risk of the sodium-cooled fast reactor is related to using metallic sodium as a coolant. In case of a breach, sodium explosively reacts with water. Fixing breaches may also prove dangerous, as the cheapest noble gas [[argon]] is also used to prevent sodium oxidation. Argon, like helium, can displace oxygen in the air and can pose [[hypoxia (environmental)|hypoxia]] concerns, so workers may be exposed to this additional risk. This is a pertinent problem as demonstrated by the events at the [[LMFBR|loop type]] [[Monju Nuclear Power Plant|Prototype Fast Breeder Reactor Monju]] at Tsuruga, Japan.<ref>{{cite news |title=Japan Strains to Fix a Reactor Damaged Before Quake |url=https://www.nytimes.com/2011/06/18/world/asia/18japan.html | work=The New York Times | first=Hiroko |last=Tabuchi |date=17 June 2011}}</ref>
Using lead or molten salts mitigates this problem by making the coolant less reactive and allowing a high freezing temperature and low pressure in case of a leak. Disadvantages of lead compared to sodium are much higher viscosity, much higher density, lower heat capacity, and more radioactive neutron activation products.

In many cases, there is already a large amount of experience built up with numerous proof of concept Gen IV designs. For example, the reactors at [[Fort St. Vrain Generating Station]] and [[HTR-10]] are similar to the proposed Gen IV [[VHTR]] designs, and the [[LMFBR|pool type]] [[EBR-II]], [[Phénix]] and [[BN-600]] reactor are similar to the proposed pool type Gen IV Sodium Cooled Fast reactors being designed.

Nuclear engineer [[David Lochbaum]] however argues that safety risks may be greater initially as reactor operators have little experience with the new design "the problem with new reactors and accidents is twofold: scenarios arise that are impossible to plan for in simulations; and humans make mistakes".<ref name=safe />
As one director of a U.S. research laboratory put it, "fabrication, construction, operation, and maintenance of new reactors will face a steep learning curve: advanced technologies will have a heightened risk of accidents and mistakes. The technology may be proven, but people are not".<ref name=safe>{{cite journal |author=Benjamin K. Sovacool |date=August 2010 |title=A Critical Evaluation of Nuclear Power and Renewable Electricity in Asia |url=http://www.informaworld.com/smpp/content~content=a923050767~db=all~jumptype=rss |journal=Journal of Contemporary Asia |volume=40 |issue=3 |page=381}}</ref>

== Table of designs ==

{| class=wikitable
|+ Summary of designs for generation IV reactors<ref>{{cite web |title=GIF R&D Outlook for Generation IV Nuclear Energy Systems |date=21 August 2009 |url=https://www.gen-4.org/gif/upload/docs/application/pdf/2013-09/gif_rd_outlook_for_generation_iv_nuclear_energy_systems.pdf |accessdate=August 30, 2018}}</ref>
|-
! System
! Neutron Spectrum
! Coolant
! Temperature (°C)
! Fuel Cycle
! Size (MW)
!Example developers
|-
| [[Very-high-temperature reactor|VHTR]]
| Thermal
| Helium
| 900–1000
| Open
| 250–300
|[[Japan Atomic Energy Agency|JAEA]] ([[High-temperature engineering test reactor|HTTR]]), [[Tsinghua University]] ([[HTR-10]]), [[X-energy]]<ref name="energy.gov">{{cite web|title=Energy Department Announces New Investments in Advanced Nuclear Power Reactors…|url=https://www.energy.gov/articles/energy-department-announces-new-investments-advanced-nuclear-power-reactors-help-meet|website=[[United States Department of Energy|US Department of Energy]]|accessdate=16 January 2016}}</ref>
|-
| [[Sodium-cooled fast reactor|SFR]]
| Fast
| Sodium
| 550
| Closed
| 30–150, 300–1500, 1000–2000
|[[TerraPower]] ([[Traveling wave reactor|TWR]]), [[Toshiba]] ([[Toshiba 4S|4S]]), [[GE Hitachi Nuclear Energy]] ([[PRISM (reactor)|PRISM]])
|-
| [[Supercritical water reactor|SCWR]]
| Thermal or fast
| Water
| 510–625
| Open or closed
| 300–700, 1000–1500
|
|-
| [[Gas-cooled fast reactor|GFR]]
| Fast
| Helium
| 850
| Closed
| 1200
|[[Energy Multiplier Module]]
|-
| [[Lead-cooled fast reactor|LFR]]
| Fast
| Lead
| 480–800
| Closed
| 20–180, 300–1200, 600–1000
|
|-
| [[Molten salt reactor|MSR]]
| Fast or thermal
| Fluoride or chloride salts
| 700–800
| Closed
| 250, 1000
|[[Seaborg Technologies]], [[TerraPower]], [[Stable Salt Reactor|Moltex Energy]], [[Flibe Energy]] ([[Liquid fluoride thorium reactor|LFTR]]), [[Transatomic Power]], Thorium Tech Solution ([[Fuji Molten Salt Reactor|FUJI MSR]]), Terrestrial Energy ([[IMSR]]), [[Southern Company Services|Southern Company]]<ref name="energy.gov"/>
|-
| [[Dual fluid reactor|DFR]]
| Fast
| Lead
| 1000
| Closed
| 500–1500
| Institute for Solid-State Nuclear Physics<ref name=ifk>{{cite web |url=https://festkoerper-kernphysik.de/dfr.pdf |title=Dual Fluid Reactor - IFK |date=2013-06-16 |website=festkoerper-kernphysik.de |publisher= Institut für Festkörper-Kernphysik |format=PDF |location=Berlin, Germany |access-date=2017-08-28}}</ref>
|}

== See also ==
{{portal|Energy|Nuclear technology}}
{{colbegin}}
* [[Nuclear reactor]]
* [[Nuclear material]]
* [[Nuclear physics]]
* [[List of reactor types#Reactor types|List of reactor types]]
* [[Generation II reactor]]
* [[Generation III reactor]]
* [[Integral Fast Reactor]]
* [[Liquid fluoride thorium reactor]]
* [[Breeder reactor]]
* [[Small modular reactor]]
* [[List of nuclear reactors]]
{{colend}}

==References==
{{Reflist|30em}}

== External links ==
* [https://inlportal.inl.gov/portal/server.pt?open=514&objID=1361&parentname=CommunityPage&parentid=10&mode=2&in_hi_userid=200&cached=true Article from Idaho National Laboratory detailing some current efforts at developing Gen. IV reactors.]
* [http://www.gen-4.org/ Generation IV International Forum (GIF)]
* [https://web.archive.org/web/20070205115654/http://nuclear.energy.gov/genIV/neGenIV1.html U.S. Department of Energy Office of Nuclear Energy, Science and Technology]
* [https://web.archive.org/web/20060512033030/http://www.engr.utk.edu/nuclear/colloquia/slides/Gen%20IV%20U-Tenn%20Presentation.pdf Gen IV presentation]
* [http://www.ecology.at/ecology/files/pr577_1.pdf Science or Fiction - Is there a Future for Nuclear?] (Nov. 2007) - A publication from the Austrian [[Ecology Institute (Austria)|Ecology Institute]] about 'Generation IV' and Fusion reactors.
* {{cite web |url=http://memagazine.asme.org/Articles/2011/December/Nuclear_Power_After_Fukushima.cfm |title=Nuclear Power After Fukushima |author=Gail H. Marcus |date=December 2011 |website=Mechanical Engineering (the magazine of [[ASME]]) |accessdate=23 January 2012}} "In the wake of a severe plant accident, advanced reactor designs are getting renewed attention."
* [http://www.itheo.org/ International Thorium Energy Organisation - www.IThEO.org]
* [http://www.ithec.org/ International Thorium Energy Committee - iThEC]

{{Nuclear fission reactors}}

[[Category:Nuclear power reactor types]]
[[Category:Idaho National Laboratory]]

Benutzer:Snackroeg/Kernreaktoren der Generation 5

2018-12-10T11:04:29Z

Boundarylayer: /* Sodium-cooled fast reactor (SFR) */

{{update|date=October 2017}}
[[File:GenIVRoadmap-en.svg|thumb|480px|Nuclear Energy Systems Deployable no later than 2030 and offering significant advances in sustainability, safety and reliability, and economics]]

'''Generation IV reactors''' ('''Gen IV''') are a set of [[nuclear reactor]] designs currently being researched for commercial applications by the Generation IV International Forum, with [[Technology readiness level]]s varying between the level requiring a demonstration, to economical competitive implementation.<ref name=Locatelli>{{Cite journal|last=Locatelli|first=Giorgio|last2=Mancini|first2=Mauro|last3=Todeschini|first3=Nicola|date=2013-10-01|title=Generation IV nuclear reactors: Current status and future prospects|journal=Energy Policy|volume=61|pages=1503–1520|doi=10.1016/j.enpol.2013.06.101}}</ref> They are motivated by a variety of goals including improved safety, sustainability, efficiency, and cost.

The most developed Gen IV reactor design, the [[sodium fast reactor]], has received the greatest share of funding over the years with a number of demonstration facilities operated, the principle Gen IV aspect of the design, relates in largest part to the development of a sustainable closed [[Nuclear_fuel_cycle#Plutonium_cycle|fuel cycle]] for the reactor. Amongst nuclear engineers the [[molten-salt reactor]], the least developed and funded technology, is considered as potentially having the greatest [[Passive nuclear safety|inherent safety]] of the six models.<ref>{{cite web|url=https://www.scientificamerican.com/article/can-sodium-save-nuclear-power/|title=Can Sodium Save Nuclear Power?|publisher=}}</ref><ref>{{cite journal |last1=Moir |first1=Ralph |last2=Teller |first2=Edward |year=2005 |title=Thorium-Fueled Underground Power Plant Based on Molten Salt Technology |journal=Nuclear Technology |volume=151 |issue=3 |pages=334–340 |url=http://www.new.ans.org/pubs/journals/nt/a_3655 |accessdate=March 22, 2012 }}</ref> While the [[hydrogen economy]], the [[high temperature electrolysis|thermochemical production]] of hydrogen to synthesize [[Carbon-neutral fuel]]s, is deemed as strengthening the economic case for the two most efficient models, the [[Very-high-temperature reactor|high temperature reactor]] designs.<ref name=Locatelli/>

The majority of the 6 designs are generally not expected to be available for commercial construction until 2020–30.<ref name="Generation IV">{{cite web|url=http://www.world-nuclear.org/info/Nuclear-Fuel-Cycle/Power-Reactors/Generation-IV-Nuclear-Reactors/|title=Generation IV Nuclear Reactors: WNA - World Nuclear Association|website=www.world-nuclear.org}}</ref> Presently the majority of reactors in operation around the world are considered [[Generation II reactor|second generation reactor]] systems, as the vast majority of the [[Nuclear reactor#Classification by generation|first generation]] systems were retired some time ago, and there are only a dozen or so [[Generation III reactor]]s in operation as of 2014.
[[Nuclear reactor#Generation V+ reactors|Generation V reactors]] refer to reactors that are purely theoretical and are therefore not yet considered feasible in the short term, resulting in limited [[R&D]] funding.

== History ==
The Generation IV International Forum (GIF) is "a co-operative international endeavour which was set up to carry out the research and development needed to establish the feasibility and performance capabilities of the next generation nuclear energy systems."<ref>{{Cite web|url=https://www.gen-4.org/gif/jcms/c_9260/public|title=GIF Portal - Home - Public|website=www.gen-4.org|access-date=2016-07-25}}</ref> It was founded in 2001. Currently active members of the Generation IV International Forum (GIF) include: [[Australia]], [[Canada]], [[China]], the [[European Atomic Energy Community]] (Euratom), [[France]], [[Japan]], [[Russia]], [[South Africa]], [[South Korea]], [[Switzerland]], and the [[United States]]. The non-active members are [[Argentina]], [[Brazil]], and the [[United Kingdom]].<ref name="gen-4">{{cite web|url=https://www.gen-4.org/gif/jcms/c_9492/members|title=GIF Membership|website=gen-4.org|accessdate=28 October 2014}}</ref> Switzerland joined in 2002, Euratom in 2003, and China and Russia in 2006. The remaining countries (excluding Australia) were founding members.<ref name="gen-4" />

The 36th GIF meeting in [[Brussels]] was held in November 2013.<ref>{{cite web|url=https://www.energy.gov/ne/articles/generation-iv-international-forum-updates-technology-roadmap-and-builds-future|title=generation IV international forum updates technology roadmap and builds future. DOE}}</ref><ref>{{cite web|url=http://events.r20.constantcontact.com/register/event?llr=mscrkjkab&oeidk=a07e7melf609716b2c6 |title=The Generation IV international forum holds their 36th meeting on Monday 18th Nov 2013 in Brussels }}{{dead link|date=January 2017 |bot=InternetArchiveBot |fix-attempted=yes }}</ref> The ''Technology Roadmap Update for Generation IV Nuclear Energy Systems'' was published in January 2014 which details R&D objectives for the next decade.<ref>{{cite web|url=https://www.gen-4.org/gif/upload/docs/application/pdf/2014-03/gif-tru2014.pdf|archive-url=https://web.archive.org/web/20140625102915/https://www.gen-4.org/gif/upload/docs/application/pdf/2014-03/gif-tru2014.pdf|dead-url=yes|archive-date=25 June 2014|title=Wayback Machine|date=25 June 2014|publisher=}}</ref> A breakdown of the reactor designs being researched by each forum member has been made available.<ref>{{cite web|url=https://www.gen-4.org/gif/upload/docs/application/pdf/2014-03/gif_overview_presentation_v9_final3_web.pdf|archive-url=https://web.archive.org/web/20140708023538/https://www.gen-4.org/gif/upload/docs/application/pdf/2014-03/gif_overview_presentation_v9_final3_web.pdf|dead-url=yes|archive-date=8 July 2014|title=Wayback Machine|date=8 July 2014|publisher=}}</ref>

[[Nuclear power in Australia|Australia]] joined the forum in 2016.<ref>{{cite web|url=https://www.gen-4.org/gif/jcms/c_71564/australia-joins-the-generation-iv-international-forum|archiveurl=https://archive.today/20160907131656/https://www.gen-4.org/gif/jcms/c_71564/australia-joins-the-generation-iv-international-forum|deadurl=yes|title=GIF Portal - Australia joins the Generation IV International Forum|date=7 September 2016|archivedate=7 September 2016|publisher=}}</ref>

In January 2018, it was reported that "the first installation of the pressure vessel cover of the world's first Gen IV reactor" had been completed on the [[HTR-PM]].<ref>{{cite web|url=http://www.world-nuclear-news.org/NN-First-HTR-PM-vessel-head-in-place-0401185.html|title=First HTR-PM vessel head in place - World Nuclear News|website=www.world-nuclear-news.org}}</ref>

== Reactor types ==
Many reactor types were considered initially; however, the list was downsized to focus on the most promising technologies and those that could most likely meet the goals of the Gen IV initiative.<ref name="Generation IV"/> Three systems are nominally [[thermal reactor]]s and four are [[fast reactor]]s. The Very High Temperature Reactor (VHTR) is also being researched for potentially providing high quality process heat for [[thermochemical cycle|hydrogen production]]. The fast reactors offer the possibility of burning [[actinides]] to further reduce waste and of being able to "[[breeder reactor|breed more fuel]]" than they consume. These systems offer significant advances in sustainability, safety and reliability, economics, proliferation resistance (depending on perspective) and physical protection.

=== Thermal reactors ===
A [[Thermal-neutron reactor|thermal reactor]] is a [[nuclear reactor]] that uses slow or [[thermal neutrons]]. A [[neutron moderator]] is used to slow the [[neutron]]s emitted by fission to make them more likely to be captured by the fuel.

==== Very-high-temperature reactor (VHTR) ====
[[File:Very High Temperature Reactor.svg|right|thumb|Very-High-Temperature Reactor (VHTR)]]
{{Main article|Very high temperature reactor}}
{{see also|Fort St. Vrain Generating Station|High-temperature engineering test reactor|HTR-10}}
The '''very high temperature reactor''' concept uses a [[graphite]]-moderated core with a once-through [[uranium]] fuel cycle, using helium or molten salt as the [[Very high temperature reactor#Coolant|coolant]]. This reactor design envisions an outlet temperature of 1,000 °C. The reactor core can be either a prismatic-block or a [[pebble bed reactor]] design. The high temperatures enable applications such as process heat or [[hydrogen]] production via the thermochemical [[Sulfur-iodine cycle|iodine-sulfur]] process. It would also be [[Passive nuclear safety|passively safe]].

The planned construction of the first VHTR, the South African PBMR ([[pebble bed modular reactor]]), lost government funding in February, 2010.<ref>[http://www.powergenworldwide.com/index/display/articledisplay/6322207443/articles/power-engineering-international/volume-18/Issue_3/regulars/world-news/INTERNATIONAL.html South Africa to stop funding Pebble Bed nuclear reactor] {{webarchive|url=https://web.archive.org/web/20100909172743/http://www.powergenworldwide.com/index/display/articledisplay/6322207443/articles/power-engineering-international/volume-18/Issue_3/regulars/world-news/INTERNATIONAL.html |date=2010-09-09 }}</ref> A pronounced increase of costs and concerns about possible unexpected technical problems had discouraged potential investors and customers.

The [[People's Republic of China]] began construction of a 200-MW High Temperature Pebble bed reactor in 2012 as a successor to its [[HTR-10]].<ref>{{cite web|url=http://www.nucnet.org/all-the-news/2013/01/07/china-begins-construction-of-first-generation-iv-htr-pm-unit|title=China Begins Construction Of First Generation IV HTR-PM Unit|first=Central Office, NucNet a.s.b.l., Brussels,|last=Belgium|website=www.nucnet.org}}</ref>

Also in 2012, as part of the [[Next Generation Nuclear Plant]] competition, [[Idaho National Laboratory]] approved a design similar to [[Areva]]'s prismatic block [https://web.archive.org/web/20150722041246/http://us.areva.com/EN/home-3225/areva-inc-areva-htgr.html Antares reactor] as the chosen [[HTGR]] to be deployed as a prototype by 2021. It was in competition with [[General Atomics]]' [[Gas turbine modular helium reactor]] and [[Westinghouse Electric Company|Westinghouse]]'s [[Pebble Bed Modular Reactor]].<ref name="World nuclear news">{{cite web|url=http://www.world-nuclear-news.org/NN-Areva_modular_reactor_selected_for_NGNP_development-1502124.html|title=INL approves Antares design}}</ref>

[[X-energy]] was awarded a five-year $53M U.S. Department of Energy Advanced Reactor Concept Cooperative Agreement award to advance elements of their reactor development.<ref>{{cite web|url=https://www.x-energy.com/doe-partnership|title=x-energy - DOE Partnership|website=x-energy}}</ref>
The [[X-energy#Reactor Design|Xe-100]] is a pebble-bed modular reactor and will generate 200-MWt and approximately 76-MWe. The standard Xe-100 "four-pack" plant generates approximately 300-MWe and will fit on as few as 13 acres. All of the components for the Xe-100 will be road-transportable, and will be installed, rather than constructed, at the project site to streamline construction.<ref name="X-energy">{{cite web|url=https://www.x-energy.com/|title=x-energy|website=x-energy}}</ref>

==== Molten-salt reactor (MSR) ====
[[File:Molten Salt Reactor.svg|right|thumb|Molten Salt Reactor (MSR)]]
{{Main article|Molten salt reactor}}
{{see also|Liquid fluoride thorium reactor}}
A '''molten salt reactor'''<ref name="Roadmap"/> is a type of [[nuclear reactor]] where the primary [[coolant]], or even the fuel itself is a molten salt mixture. There have been many designs put forward for this type of reactor and a few prototypes built. The early concepts and many current ones rely on [[nuclear fuel]], perhaps [[uranium tetrafluoride]] (UF4) or [[thorium tetrafluoride]] (ThF4), dissolved in molten [[fluoride]] salt. The fluid would reach [[Nuclear reactor physics#Criticality|criticality]] by flowing into a core where [[graphite]] would serve as the [[neutron moderator|moderator]]. Many current concepts rely on fuel that is dispersed in a graphite matrix with the molten salt providing low pressure, high temperature cooling.

The Gen IV MSR is more accurately termed an [[epithermal neutron|epithermal reactor]] than a thermal reactor due to the average speed of the neutrons that would cause the fission events within its fuel being faster than [[thermal neutron]]s.<ref>{{cite web |url=https://inlportal.inl.gov/portal/server.pt?open=514&objID=1361&parentname=CommunityPage&parentid=10&mode=2&in_hi_userid=200&cached=true |title=Idaho National Laboratory detailing some current efforts at developing Gen. IV reactors}}</ref>

The principle of a MSR can be used for thermal, epithermal and fast reactors. Since 2005 the focus has moved towards a fast spectrum MSR (MSFR).<ref>H. Boussier, S. Delpech, V. Ghetta et Al. : The Molten Salt Reactor (MSR) in Generation IV: Overview and Perspectives, GIF SYMPOSIUM PROCEEDINGS/2012 ANNUAL REPORT, NEA No. 7141, pp95 [https://www.gen-4.org/gif/jcms/c_44720/annual-reports]
</ref>

While most MSR designs being pursued are largely derived from the 1960s [[Molten-Salt Reactor Experiment]] (MSRE), variants of molten salt technology include the conceptual ''[[Dual fluid reactor]]'' which is being designed with lead as a cooling medium but molten salt fuel, commonly as the metal chloride e.g. [[Plutonium(III) chloride]], to aid in greater "nuclear waste" closed-fuel cycle capabilities.
Other notable approaches differing substantially from MSRE include the ''[[Stable Salt Reactor]]'' (SSR) concept promoted by MOLTEX, which encases the molten salt in hundreds of the common solid [[fuel rod]]s that are already well established in the nuclear industry. This latter British design was found to be the most competitive for [[Small modular reactor]] development by a British-based consultancy firm ''Energy Process Development'' in 2015.<ref>{{cite web|url=http://www.daretothink.org/europe-moltex-stable-salt-reactor/|title=Europe: Moltex' Stable Salt Reactor|date=20 April 2015|publisher=}}</ref><ref>{{cite web|url=http://analysis.nuclearenergyinsider.com/moltex-energy-sees-uk-canada-smr-licensing-springboard-asia|title=Moltex Energy sees UK, Canada SMR licensing as springboard to Asia - Nuclear Energy Insider|website=analysis.nuclearenergyinsider.com}}</ref>

Another notable feature of the MSR is the possibility of a [[Thermal-neutron reactor|thermal spectrum]] nuclear [[Nuclear fuel cycle#Fuel cycles|waste-burner]]. Conventionally only fast spectrum reactors have been considered viable for [[Nuclear fuel cycle#Minor actinides recycling|utilization or reduction]] of the [[Spent nuclear fuel|spent nuclear stockpiles]]. The conceptual viability of a thermal waste-burner was first shown in a whitepaper by [[Seaborg Technologies]] spring 2015.<ref name="Seaborg Whitepaper 2015">{{cite web|url=https://seaborg.dk/s/Seaborg-whitepaper-2015.pdf|title=Thermal MSR waste burner benchmark}}</ref> Thermal waste-burning was achieved by replacing a fraction of the [[uranium]] in the spent nuclear fuel with [[thorium]]. The net production rate of [[transuranium element]] (e.g. [[plutonium]] and [[americium]]) is reduced below the consumption rate, thus reducing the magnitude of the [[Radioactive waste|nuclear storage problem]], without the [[nuclear proliferation]] concerns and other [[Fast-neutron reactor#Disadvantages|technical issues]] associated with a [[Fast-neutron reactor|fast reactor]].

==== Supercritical-water-cooled reactor (SCWR) ====
[[File:Supercritical-Water-Cooled Reactor.svg|right|thumb|Supercritical-Water-Cooled Reactor (SCWR)]]
{{Main article|Supercritical water reactor}}
The '''supercritical water reactor''' (SCWR)<ref name="Roadmap"/> is a [[reduced moderation water reactor]] concept that, due to the average speed of the neutrons that would cause the fission events within the fuel being faster than [[thermal neutron]]s, it is more accurately termed an [[epithermal neutron|epithermal reactor]] than a thermal reactor. It uses [[supercritical fluid|supercritical water]] as the working fluid. SCWRs are basically [[light water reactor]]s (LWR) operating at higher pressure and temperatures with a direct, once-through heat exchange cycle. As most commonly envisioned, it would operate on a direct cycle, much like a boiling water reactor ([[BWR]]), but since it uses supercritical water (not to be confused with [[Critical mass (nuclear)|critical mass]]) as the working fluid, it would have only one water phase present, which makes the supercritical heat exchange method more similar to a pressurized water reactor ([[Pressurized water reactor|PWR]]). It could operate at much higher temperatures than both current PWRs and BWRs.

Supercritical water-cooled reactors (SCWRs) are promising advanced nuclear systems because of their high [[thermal efficiency]] (i.e., about 45% vs. about 33% efficiency for current LWRs) and considerable plant simplification.

The main mission of the SCWR is generation of low-cost [[electricity]]. It is built upon two proven technologies, LWRs, which are the most commonly deployed power generating reactors in the world, and superheated [[fossil fuel]] fired [[boiler]]s, a large number of which are also in use around the world. The SCWR concept is being investigated by 32 organizations in 13 countries.{{citation needed|date=October 2012}}

Because SCWRs are water reactors they share the steam explosion and radioactive steam release hazards of BWRs and LWRs as well as the need for extremely expensive heavy duty pressure vessels, pipes, valves, and pumps. These shared problems are inherently more severe for SCWRs due to operation at higher temperatures.

A SCWR Design under development is the [[VVER]]-1700/393 (VVER-SCWR or VVER-SKD) — a Russian Supercritical-water-cooled reactor with double-inlet-core and a [[breeder reactor|breeding ratio]] of 0.95.<ref name="powertecrussia.com">{{cite web |url=http://www.powertecrussia.com/blog/tag/nuclear-power/ |title=Technology Developments & Plant Efficiency for the Russian Nuclear Power Generation Market Wednesday |date=March 24, 2010}}</ref>

=== Fast reactors ===
A [[Fast-neutron reactor|fast reactor]] directly uses the fast neutrons emitted by fission, without moderation. Unlike thermal neutron reactors, fast neutron reactors can be configured to "'''burn'''", or fission, all [[actinides]], and given enough time, therefore drastically reduce the actinides fraction in [[spent nuclear fuel]] produced by the present world fleet of thermal neutron [[light water reactor]]s, thus closing the [[nuclear fuel cycle]]. Alternatively, if configured differently, they can also [[breeder reactor|'''breed''']] more actinide fuel than they consume.

==== Gas-cooled fast reactor (GFR) ====
[[File:Gas-Cooled Fast Reactor Schemata.svg|right|thumb|Gas-Cooled Fast Reactor (GFR)]]
{{Main article|Gas-cooled fast reactor}}
The '''gas-cooled fast reactor''' (GFR)<ref name="Roadmap"/> system features a fast-neutron spectrum and closed fuel cycle for efficient conversion of [[Fertile material|fertile uranium]] and management of actinides. The reactor is [[helium]]-cooled and with an outlet temperature of 850 °C it is an evolution of the [[very-high-temperature reactor]] (VHTR) to a more sustainable fuel cycle. It will use a direct [[Brayton cycle]] [[Closed-cycle gas turbine|gas turbine]] for high thermal efficiency. Several fuel forms are being considered for their potential to operate at very high temperatures and to ensure an excellent retention of [[Nuclear fission|fission]] products: composite [[ceramic]] fuel, advanced fuel particles, or ceramic clad elements of actinide compounds. Core configurations are being considered based on pin- or plate-based fuel assemblies or prismatic blocks.

The European Sustainable Nuclear Industrial Initiative is funding three Generation IV reactor systems, one of which is a gas-cooled fast reactor, called ''Allegro'', 100 MW(t), which will be built in a central or eastern European country with construction expected to begin in 2018.<ref name="euronuclear.org">{{cite web|url=https://www.euronuclear.org/1-information/news/Gen-IV.htm |title=The European Sustainable Nuclear Industrial Initiative (ESNII) will support three Generation IV reactor systems: a sodium-cooled fast reactor, or SFR, called ''Astrid'' that is proposed by France; a gas-cooled fast reactor, GFR, called ''Allegro'' supported by central and eastern Europe; and a lead-cooled fast reactor, LFR, technology pilot called ''Myrrha'' that is proposed by Belgium |deadurl=yes |archiveurl=https://web.archive.org/web/20131009042600/http://euronuclear.org/1-information/news/Gen-IV.htm |archivedate=2013-10-09 |df= }}</ref> The central European [[Visegrád Group]] are committed to pursuing the technology.<ref>{{cite web |url=http://www.alphagalileo.org/ViewItem.aspx?ItemId=133111&CultureCode=en |title=The V4G4 Centre of Excellence for performing joint research, development and innovation in the field of Generation-4 (G4) nuclear reactors have been established. 20 July 2013 National Center for Nuclear Research (NCBJ)}}</ref> In 2013 German, British, and French institutes finished a 3-year collaboration study on the follow on industrial scale design, known as ''GoFastR''.<ref>{{cite web|url=http://www.ist-world.org/ProjectDetails.aspx?ProjectId=5cb8f3f283574cc6b2bdbf72533172d8 |title=the European Gas cooled Fast Reactor |deadurl=yes |archiveurl=https://web.archive.org/web/20131213091046/http://www.ist-world.org/ProjectDetails.aspx?ProjectId=5cb8f3f283574cc6b2bdbf72533172d8 |archivedate=2013-12-13 |df= }}</ref> They were funded by the EU's 7th FWP [[framework programme]], with the goal of making a sustainable VHTR.<ref>{{cite web |url=http://www.2020-horizon.com/GOFASTR-European-Gas-Cooled-Fast-Reactor%28GOFASTR%29-s312.html |title=The GOFASTR research program}}</ref>

==== Sodium-cooled fast reactor (SFR) ====
[[File:Sodium-Cooled Fast Reactor Schemata.svg|right|thumb|Pool design Sodium-Cooled Fast Reactor (SFR)]]
{{Main article|Sodium-cooled fast reactor}}
{{see also|Experimental Breeder Reactor II|S-PRISM|Toshiba 4S|CFR-600}}

The two largest commercial sodium cooled fast reactors are both in Russia, the [[BN-600]] and the recently completed [[BN-800]](800 MW). The largest ever operated was the [[Superphenix]] reactor at over 1200 MW of electrical output, successfully operating for a number of years in France before being decommissioned in 1996. In India, the [[Fast Breeder Test Reactor]] reached criticality in October 1985. In September 2002, fuel [[burn up]] efficiency in the FBTR for the first time reached the 100,000 megawatt-days per metric ton uranium (MWd/MTU) mark. This is considered an important milestone in Indian breeder reactor technology. Using the experience gained from the operation of the FBTR, the [[Prototype Fast Breeder Reactor]], a 500 MWe Sodium cooled fast reactor is being built at a cost of INR 5,677 crores (~US$900 million) and is expected to be critical by June 2019. The PFBR will be followed by six more Commercial Fast Breeder Reactors (CFBRs) of 600 MWe each.

The Gen IV SFR<ref name="Roadmap"/> is a project that builds on two closely related existing projects, the liquid metal [[Breeder reactor#Fast breeder reactor|fast breeder reactor]] and the [[integral fast reactor]].

The goals are to increase the efficiency of uranium usage by [[breeder reactor|breeding]] plutonium and eliminating the need for [[transuranic]] isotopes ever to leave the site. The reactor design uses an unmoderated core running on [[fast neutron]]s, designed to allow any transuranic isotope to be consumed (and in some cases used as fuel). In addition to the benefits of removing the long [[half-life]] transuranics from the waste cycle, the SFR fuel expands when the reactor overheats, and the chain reaction automatically slows down. In this manner, it is passively safe.<ref>{{cite web |url=http://www.ne.anl.gov/About/hn/logos-winter02-psr.shtml|title=Passively safe reactors rely on nature to keep them cool|author=David Baurac}}</ref>

The SFR reactor concept is cooled by liquid [[sodium]] and fueled by a metallic alloy of uranium and [[plutonium]] or [[spent nuclear fuel]], the "nuclear waste" of [[light water reactor]]s. The SFR fuel is contained in steel cladding with liquid sodium filling in the space between the clad elements which make up the fuel assembly. One of the design challenges of an SFR is the risks of handling sodium, which reacts explosively if it comes into contact with water. However, the use of liquid metal instead of water as coolant allows the system to work at atmospheric pressure, reducing the risk of leakage.

[[File:Ifr concept.jpg|thumb|375px|The sustainable fuel-cycle proposed in the 1990s [[Integral fast reactor]] concept (color), an animation of the [[pyroprocessing]] technology is also available.<ref>{{cite web |url=https://www.youtube.com/watch?v=cBThTwFhRlA |title=Historical video about the Integral Fast Reactor (IFR) concept. Uploaded by - Nuclear Engineering at Argonne}}</ref>]]
[[File:IFR concept.png|thumb|375px|IFR concept (Black and White with clearer text)]]

The European Sustainable Nuclear Industrial Initiative is funding three Generation IV reactor systems, one of which is a sodium-cooled fast reactor, called ''[[ASTRID (reactor)|ASTRID]]'', Advanced Sodium Technical Reactor for Industrial Demonstration, [[Areva]], [[Commissariat à l'énergie atomique et aux énergies alternatives|CEA]] and [[Électricité de France|EDF]] are leading the design with British collaboration.<ref>{{cite web |url=http://www.power-eng.com/articles/2010/11/areva--cea-secure.html |title=Areva, CEA secure EUR650m funding to develop ASTRID sodium-cooled Generation IV reactor 11/11/2010}}</ref><ref>{{cite web |url=http://www.powermag.com/uk-and-france-sign-landmark-civil-nuclear-cooperation-agreement/ |title=UK and France Sign Landmark Civil Nuclear Cooperation Agreement 02/22/2012 . POWERnews}}</ref> Astrid will be rated about 600 MWe and is proposed to be built in France, near to the [[Phénix]] reactor. A final decision in construction is to be made in 2019<ref name="euronuclear.org"/>

The [[China|PRC]]'s first commercial-scale, 800 MWe, fast neutron reactor, to be situated near [[Sanming]] in [[Fujian province]] will be a SFR. In 2009 an agreement was signed that would entail the Russian [[BN-800 reactor]] design to be sold to the PRC once it is completed, this would be the first time commercial-scale fast neutron reactors have ever been exported.<ref>{{cite web |url=http://www.world-nuclear-news.org/C-Joint_venture_launched_for_Chinese_fast_reactor-3004104.html |title=Joint venture launched for Chinese fast reactor}}</ref> The BN-800 reactor became operational in 2014.

Numerous progenitors of the Gen IV SFR exist around the world, with the 400 MWe [[Fast Flux Test Facility]] operated successfully for ten years at the Hanford site in Washington State.

The 20 MWe [[EBR II]] operated successfully for over thirty years at the Idaho National Laboratory, until it was shut down in 1994.

GE Hitachi's [[PRISM (reactor)|PRISM]] reactor is a modernized and commercial implementation of the technology developed for the Integral Fast Reactor(IFR), developed by [[Argonne National Laboratory]] between 1984 and 1994. With the primary purpose of PRISM differing in the focus on burning up [[spent nuclear fuel]] from other reactors, rather than [[breeder reactor|breeding]] new fuel. Presented as an alternative to burying the spent fuel/waste, the design reduces the half lives of the fissionable elements present in spent nuclear fuel while generating electricity largely as a by-product.

==== Lead-cooled fast reactor (LFR) ====
[[File:Lead-Cooled Fast Reactor Schemata.svg|right|thumb|Lead-Cooled Fast Reactor (LFR)]]
{{Main article|Lead-cooled fast reactor}}
{{See also|MYRRHA}}
The '''lead-cooled fast reactor'''<ref name="Roadmap">{{cite journal|year=2002 |title=A Technology Roadmap for Generation IV Nuclear Energy Systems |last=US DOE Nuclear Energy Research Advisory Committee |volume=GIF-002-00 |url=http://nuclear.energy.gov/genIV/documents/gen_iv_roadmap.pdf |deadurl=yes |archiveurl=https://web.archive.org/web/20071129121214/http://nuclear.energy.gov/genIV/documents/gen_iv_roadmap.pdf |archivedate=2007-11-29 |df= }}</ref> features a fast-neutron-spectrum [[lead]] or [[lead]]/[[bismuth]] [[eutectic]] ([[Lead-bismuth eutectic|LBE]]) liquid-metal-cooled reactor with a closed [[Nuclear fuel cycle|fuel cycle]]. Options include a range of plant ratings, including a "battery" of 50 to 150 MW of electricity that features a very long refueling interval, a modular system rated at 300 to 400 MW, and a large monolithic plant option at 1,200 MW (The term ''battery'' refers to the long-life, factory-fabricated core, not to any provision for electrochemical energy conversion). The fuel is metal or nitride-based containing [[Fertile material|fertile uranium]] and [[transuranic]]s. The LFR is cooled by natural [[convection]] with a reactor outlet coolant temperature of 550 °C, possibly ranging up to 800 °C with advanced materials. The higher temperature enables the production of [[Thermochemical cycle|hydrogen by thermochemical processes]].

The European Sustainable Nuclear Industrial Initiative is funding three Generation IV reactor systems, one of which is a lead-cooled fast reactor that is also an [[Subcritical reactor|accelerator-driven sub-critical]] reactor, called ''[[MYRRHA]]'', 100 MW(t), which will be built in [[Belgium]] with construction expected to begin after 2014 and the industrial scale version, known as ''Alfred'', slated to be constructed sometime after 2017. A reduced-power model of Myrrha called ''Guinevere'' was started up at [[Mol, Belgium|Mol]] in March 2009.<ref name="euronuclear.org"/> In 2012 the research team reported that Guinevere was operational.<ref>{{cite news|last1=Hellemans|first1=Alexander|title=Reactor-Accelerator Hybrid Achieves Successful Test Run|url=http://news.sciencemag.org/physics/2012/01/reactor-accelerator-hybrid-achieves-successful-test-run|accessdate=29 December 2014|work=Science Insider|date=12 January 2012}}</ref>

Two other lead-cooled fast reactors under development are the SVBR-100, a modular 100 MWe lead-bismuth cooled fast neutron reactor concept designed by OKB [[Gidropress]] in Russia and the [[BREST (Reactor)|BREST-OD-300]] (Lead-cooled fast reactor) 300 MWe, to be developed after the SVBR-100, and built over 2016-20, it will dispense with the [[Uranium-238|fertile blanket]] around the core and will supersede the sodium cooled [[BN-600 reactor]] design, to purportedly give enhanced proliferation resistance.<ref name="powertecrussia.com"/>

== Advantages and disadvantages ==
Relative to current nuclear power plant technology, the claimed benefits for 4th generation reactors include:
* Nuclear waste that remains radioactive for a few centuries instead of millennia<ref>{{cite web |title=Strategies to Address Global Warming |url=http://www.columbia.edu/~jeh1/mailings/2009/20090713_Strategies.pdf}}</ref>
* 100–300 times more energy yield from the same amount of nuclear fuel<ref>{{cite web |title=4th Generation Nuclear Power |url=http://www.ossfoundation.us/projects/energy/nuclear}}</ref>
* Broader range of fuels, and even unencapsulated raw fuels (non-pebble [[Molten Salt Reactor|MSR]], [[Liquid fluoride thorium reactor|LFTR]]).
* In some reactors, the ability to consume existing nuclear waste in the production of electricity, that is, a Closed [[nuclear fuel cycle]]. This strengthens the argument to deem [[nuclear power as renewable energy]].
* Improved operating safety features, such as (depending on design) avoidance of pressurized operation, automatic passive (unpowered, uncommanded) reactor shutdown, avoidance of water cooling and the associated risks of loss of water (leaks or boiling) and hydrogen generation/explosion and contamination of coolant water.

Nuclear reactors do not emit CO2 during operation, although like all [[low carbon power]] sources, the mining and construction phase can result in CO2 emissions, if energy sources which are not carbon neutral (such as fossil fuels), or CO2 emitting cements are used during the construction process.
A 2012 [[Yale University]] review published in the Journal of Industrial Ecology analyzing {{CO2}} [[life cycle assessment]] (LCA) emissions from [[nuclear power]] determined that:<ref name="Warner + Heath, JoIE">{{cite journal |doi=10.1111/j.1530-9290.2012.00472.x|title=Life Cycle Greenhouse Gas Emissions of Nuclear Electricity Generation|journal=Journal of Industrial Ecology|volume=16|pages=S73–S92|year=2012|last1=Warner|first1=Ethan S|last2=Heath|first2=Garvin A}}</ref>
{{Quote|The collective LCA literature indicates that life cycle [[Greenhouse gas|GHG]] [greenhouse gas] emissions from nuclear power are only a fraction of traditional fossil sources and comparable to renewable technologies.}}
Although the paper primarily dealt with data from [[Generation II reactor]]s, and did not analyze the {{CO2}} emissions by 2050 of the presently under construction [[Generation III reactor]]s, it did summarize the Life Cycle Assessment findings of in development reactor technologies.{{Quote|FBRs ['[[Fast Breeder Reactor]]s'] have been evaluated in the LCA literature. The limited literature that evaluates this potential future technology reports [[median]] life cycle GHG emissions... similar to or lower than LWRs [Gen II [[light water reactor]]s] and purports to consume little or no [[uranium market|uranium ore]].}}

A specific risk of the sodium-cooled fast reactor is related to using metallic sodium as a coolant. In case of a breach, sodium explosively reacts with water. Fixing breaches may also prove dangerous, as the cheapest noble gas [[argon]] is also used to prevent sodium oxidation. Argon, like helium, can displace oxygen in the air and can pose [[hypoxia (environmental)|hypoxia]] concerns, so workers may be exposed to this additional risk. This is a pertinent problem as demonstrated by the events at the [[LMFBR|loop type]] [[Monju Nuclear Power Plant|Prototype Fast Breeder Reactor Monju]] at Tsuruga, Japan.<ref>{{cite news |title=Japan Strains to Fix a Reactor Damaged Before Quake |url=https://www.nytimes.com/2011/06/18/world/asia/18japan.html | work=The New York Times | first=Hiroko |last=Tabuchi |date=17 June 2011}}</ref>
Using lead or molten salts mitigates this problem by making the coolant less reactive and allowing a high freezing temperature and low pressure in case of a leak. Disadvantages of lead compared to sodium are much higher viscosity, much higher density, lower heat capacity, and more radioactive neutron activation products.

In many cases, there is already a large amount of experience built up with numerous proof of concept Gen IV designs. For example, the reactors at [[Fort St. Vrain Generating Station]] and [[HTR-10]] are similar to the proposed Gen IV [[VHTR]] designs, and the [[LMFBR|pool type]] [[EBR-II]], [[Phénix]] and [[BN-600]] reactor are similar to the proposed pool type Gen IV Sodium Cooled Fast reactors being designed.

== Table of designs ==

{| class=wikitable
|+ Summary of designs for generation IV reactors<ref>{{cite web |title=GIF R&D Outlook for Generation IV Nuclear Energy Systems |date=21 August 2009 |url=https://www.gen-4.org/gif/upload/docs/application/pdf/2013-09/gif_rd_outlook_for_generation_iv_nuclear_energy_systems.pdf |accessdate=August 30, 2018}}</ref>
|-
! System
! Neutron Spectrum
! Coolant
! Temperature (°C)
! Fuel Cycle
! Size (MW)
!Example developers
|-
| [[Very-high-temperature reactor|VHTR]]
| Thermal
| Helium
| 900–1000
| Open
| 250–300
|[[Japan Atomic Energy Agency|JAEA]] ([[High-temperature engineering test reactor|HTTR]]), [[Tsinghua University]] ([[HTR-10]]), [[X-energy]]<ref name="energy.gov">{{cite web|title=Energy Department Announces New Investments in Advanced Nuclear Power Reactors…|url=https://www.energy.gov/articles/energy-department-announces-new-investments-advanced-nuclear-power-reactors-help-meet|website=[[United States Department of Energy|US Department of Energy]]|accessdate=16 January 2016}}</ref>
|-
| [[Sodium-cooled fast reactor|SFR]]
| Fast
| Sodium
| 550
| Closed
| 30–150, 300–1500, 1000–2000
|[[TerraPower]] ([[Traveling wave reactor|TWR]]), [[Toshiba]] ([[Toshiba 4S|4S]]), [[GE Hitachi Nuclear Energy]] ([[PRISM (reactor)|PRISM]])
|-
| [[Supercritical water reactor|SCWR]]
| Thermal or fast
| Water
| 510–625
| Open or closed
| 300–700, 1000–1500
|
|-
| [[Gas-cooled fast reactor|GFR]]
| Fast
| Helium
| 850
| Closed
| 1200
|[[Energy Multiplier Module]]
|-
| [[Lead-cooled fast reactor|LFR]]
| Fast
| Lead
| 480–800
| Closed
| 20–180, 300–1200, 600–1000
|
|-
| [[Molten salt reactor|MSR]]
| Fast or thermal
| Fluoride or chloride salts
| 700–800
| Closed
| 250, 1000
|[[Seaborg Technologies]], [[TerraPower]], [[Stable Salt Reactor|Moltex Energy]], [[Flibe Energy]] ([[Liquid fluoride thorium reactor|LFTR]]), [[Transatomic Power]], Thorium Tech Solution ([[Fuji Molten Salt Reactor|FUJI MSR]]), Terrestrial Energy ([[IMSR]]), [[Southern Company Services|Southern Company]]<ref name="energy.gov"/>
|-
| [[Dual fluid reactor|DFR]]
| Fast
| Lead
| 1000
| Closed
| 500–1500
| Institute for Solid-State Nuclear Physics<ref name=ifk>{{cite web |url=https://festkoerper-kernphysik.de/dfr.pdf |title=Dual Fluid Reactor - IFK |date=2013-06-16 |website=festkoerper-kernphysik.de |publisher= Institut für Festkörper-Kernphysik |format=PDF |location=Berlin, Germany |access-date=2017-08-28}}</ref>
|}

== See also ==
{{portal|Energy|Nuclear technology}}
{{colbegin}}
* [[Nuclear reactor]]
* [[Nuclear material]]
* [[Nuclear physics]]
* [[List of reactor types#Reactor types|List of reactor types]]
* [[Generation II reactor]]
* [[Generation III reactor]]
* [[Integral Fast Reactor]]
* [[Liquid fluoride thorium reactor]]
* [[Breeder reactor]]
* [[Small modular reactor]]
* [[List of nuclear reactors]]
{{colend}}

==References==
{{Reflist|30em}}

== External links ==
* [https://inlportal.inl.gov/portal/server.pt?open=514&objID=1361&parentname=CommunityPage&parentid=10&mode=2&in_hi_userid=200&cached=true Article from Idaho National Laboratory detailing some current efforts at developing Gen. IV reactors.]
* [http://www.gen-4.org/ Generation IV International Forum (GIF)]
* [https://web.archive.org/web/20070205115654/http://nuclear.energy.gov/genIV/neGenIV1.html U.S. Department of Energy Office of Nuclear Energy, Science and Technology]
* [https://web.archive.org/web/20060512033030/http://www.engr.utk.edu/nuclear/colloquia/slides/Gen%20IV%20U-Tenn%20Presentation.pdf Gen IV presentation]
* [http://www.ecology.at/ecology/files/pr577_1.pdf Science or Fiction - Is there a Future for Nuclear?] (Nov. 2007) - A publication from the Austrian [[Ecology Institute (Austria)|Ecology Institute]] about 'Generation IV' and Fusion reactors.
* {{cite web |url=http://memagazine.asme.org/Articles/2011/December/Nuclear_Power_After_Fukushima.cfm |title=Nuclear Power After Fukushima |author=Gail H. Marcus |date=December 2011 |website=Mechanical Engineering (the magazine of [[ASME]]) |accessdate=23 January 2012}} "In the wake of a severe plant accident, advanced reactor designs are getting renewed attention."
* [http://www.itheo.org/ International Thorium Energy Organisation - www.IThEO.org]
* [http://www.ithec.org/ International Thorium Energy Committee - iThEC]

{{Nuclear fission reactors}}

[[Category:Nuclear power reactor types]]
[[Category:Idaho National Laboratory]]

Benutzer:Snackroeg/Kernreaktoren der Generation 5

2018-12-10T11:02:18Z

Boundarylayer: /* Sodium-cooled fast reactor (SFR) */

{{update|date=October 2017}}
[[File:GenIVRoadmap-en.svg|thumb|480px|Nuclear Energy Systems Deployable no later than 2030 and offering significant advances in sustainability, safety and reliability, and economics]]

'''Generation IV reactors''' ('''Gen IV''') are a set of [[nuclear reactor]] designs currently being researched for commercial applications by the Generation IV International Forum, with [[Technology readiness level]]s varying between the level requiring a demonstration, to economical competitive implementation.<ref name=Locatelli>{{Cite journal|last=Locatelli|first=Giorgio|last2=Mancini|first2=Mauro|last3=Todeschini|first3=Nicola|date=2013-10-01|title=Generation IV nuclear reactors: Current status and future prospects|journal=Energy Policy|volume=61|pages=1503–1520|doi=10.1016/j.enpol.2013.06.101}}</ref> They are motivated by a variety of goals including improved safety, sustainability, efficiency, and cost.

The most developed Gen IV reactor design, the [[sodium fast reactor]], has received the greatest share of funding over the years with a number of demonstration facilities operated, the principle Gen IV aspect of the design, relates in largest part to the development of a sustainable closed [[Nuclear_fuel_cycle#Plutonium_cycle|fuel cycle]] for the reactor. Amongst nuclear engineers the [[molten-salt reactor]], the least developed and funded technology, is considered as potentially having the greatest [[Passive nuclear safety|inherent safety]] of the six models.<ref>{{cite web|url=https://www.scientificamerican.com/article/can-sodium-save-nuclear-power/|title=Can Sodium Save Nuclear Power?|publisher=}}</ref><ref>{{cite journal |last1=Moir |first1=Ralph |last2=Teller |first2=Edward |year=2005 |title=Thorium-Fueled Underground Power Plant Based on Molten Salt Technology |journal=Nuclear Technology |volume=151 |issue=3 |pages=334–340 |url=http://www.new.ans.org/pubs/journals/nt/a_3655 |accessdate=March 22, 2012 }}</ref> While the [[hydrogen economy]], the [[high temperature electrolysis|thermochemical production]] of hydrogen to synthesize [[Carbon-neutral fuel]]s, is deemed as strengthening the economic case for the two most efficient models, the [[Very-high-temperature reactor|high temperature reactor]] designs.<ref name=Locatelli/>

The majority of the 6 designs are generally not expected to be available for commercial construction until 2020–30.<ref name="Generation IV">{{cite web|url=http://www.world-nuclear.org/info/Nuclear-Fuel-Cycle/Power-Reactors/Generation-IV-Nuclear-Reactors/|title=Generation IV Nuclear Reactors: WNA - World Nuclear Association|website=www.world-nuclear.org}}</ref> Presently the majority of reactors in operation around the world are considered [[Generation II reactor|second generation reactor]] systems, as the vast majority of the [[Nuclear reactor#Classification by generation|first generation]] systems were retired some time ago, and there are only a dozen or so [[Generation III reactor]]s in operation as of 2014.
[[Nuclear reactor#Generation V+ reactors|Generation V reactors]] refer to reactors that are purely theoretical and are therefore not yet considered feasible in the short term, resulting in limited [[R&D]] funding.

== History ==
The Generation IV International Forum (GIF) is "a co-operative international endeavour which was set up to carry out the research and development needed to establish the feasibility and performance capabilities of the next generation nuclear energy systems."<ref>{{Cite web|url=https://www.gen-4.org/gif/jcms/c_9260/public|title=GIF Portal - Home - Public|website=www.gen-4.org|access-date=2016-07-25}}</ref> It was founded in 2001. Currently active members of the Generation IV International Forum (GIF) include: [[Australia]], [[Canada]], [[China]], the [[European Atomic Energy Community]] (Euratom), [[France]], [[Japan]], [[Russia]], [[South Africa]], [[South Korea]], [[Switzerland]], and the [[United States]]. The non-active members are [[Argentina]], [[Brazil]], and the [[United Kingdom]].<ref name="gen-4">{{cite web|url=https://www.gen-4.org/gif/jcms/c_9492/members|title=GIF Membership|website=gen-4.org|accessdate=28 October 2014}}</ref> Switzerland joined in 2002, Euratom in 2003, and China and Russia in 2006. The remaining countries (excluding Australia) were founding members.<ref name="gen-4" />

The 36th GIF meeting in [[Brussels]] was held in November 2013.<ref>{{cite web|url=https://www.energy.gov/ne/articles/generation-iv-international-forum-updates-technology-roadmap-and-builds-future|title=generation IV international forum updates technology roadmap and builds future. DOE}}</ref><ref>{{cite web|url=http://events.r20.constantcontact.com/register/event?llr=mscrkjkab&oeidk=a07e7melf609716b2c6 |title=The Generation IV international forum holds their 36th meeting on Monday 18th Nov 2013 in Brussels }}{{dead link|date=January 2017 |bot=InternetArchiveBot |fix-attempted=yes }}</ref> The ''Technology Roadmap Update for Generation IV Nuclear Energy Systems'' was published in January 2014 which details R&D objectives for the next decade.<ref>{{cite web|url=https://www.gen-4.org/gif/upload/docs/application/pdf/2014-03/gif-tru2014.pdf|archive-url=https://web.archive.org/web/20140625102915/https://www.gen-4.org/gif/upload/docs/application/pdf/2014-03/gif-tru2014.pdf|dead-url=yes|archive-date=25 June 2014|title=Wayback Machine|date=25 June 2014|publisher=}}</ref> A breakdown of the reactor designs being researched by each forum member has been made available.<ref>{{cite web|url=https://www.gen-4.org/gif/upload/docs/application/pdf/2014-03/gif_overview_presentation_v9_final3_web.pdf|archive-url=https://web.archive.org/web/20140708023538/https://www.gen-4.org/gif/upload/docs/application/pdf/2014-03/gif_overview_presentation_v9_final3_web.pdf|dead-url=yes|archive-date=8 July 2014|title=Wayback Machine|date=8 July 2014|publisher=}}</ref>

[[Nuclear power in Australia|Australia]] joined the forum in 2016.<ref>{{cite web|url=https://www.gen-4.org/gif/jcms/c_71564/australia-joins-the-generation-iv-international-forum|archiveurl=https://archive.today/20160907131656/https://www.gen-4.org/gif/jcms/c_71564/australia-joins-the-generation-iv-international-forum|deadurl=yes|title=GIF Portal - Australia joins the Generation IV International Forum|date=7 September 2016|archivedate=7 September 2016|publisher=}}</ref>

In January 2018, it was reported that "the first installation of the pressure vessel cover of the world's first Gen IV reactor" had been completed on the [[HTR-PM]].<ref>{{cite web|url=http://www.world-nuclear-news.org/NN-First-HTR-PM-vessel-head-in-place-0401185.html|title=First HTR-PM vessel head in place - World Nuclear News|website=www.world-nuclear-news.org}}</ref>

== Reactor types ==
Many reactor types were considered initially; however, the list was downsized to focus on the most promising technologies and those that could most likely meet the goals of the Gen IV initiative.<ref name="Generation IV"/> Three systems are nominally [[thermal reactor]]s and four are [[fast reactor]]s. The Very High Temperature Reactor (VHTR) is also being researched for potentially providing high quality process heat for [[thermochemical cycle|hydrogen production]]. The fast reactors offer the possibility of burning [[actinides]] to further reduce waste and of being able to "[[breeder reactor|breed more fuel]]" than they consume. These systems offer significant advances in sustainability, safety and reliability, economics, proliferation resistance (depending on perspective) and physical protection.

=== Thermal reactors ===
A [[Thermal-neutron reactor|thermal reactor]] is a [[nuclear reactor]] that uses slow or [[thermal neutrons]]. A [[neutron moderator]] is used to slow the [[neutron]]s emitted by fission to make them more likely to be captured by the fuel.

==== Very-high-temperature reactor (VHTR) ====
[[File:Very High Temperature Reactor.svg|right|thumb|Very-High-Temperature Reactor (VHTR)]]
{{Main article|Very high temperature reactor}}
{{see also|Fort St. Vrain Generating Station|High-temperature engineering test reactor|HTR-10}}
The '''very high temperature reactor''' concept uses a [[graphite]]-moderated core with a once-through [[uranium]] fuel cycle, using helium or molten salt as the [[Very high temperature reactor#Coolant|coolant]]. This reactor design envisions an outlet temperature of 1,000 °C. The reactor core can be either a prismatic-block or a [[pebble bed reactor]] design. The high temperatures enable applications such as process heat or [[hydrogen]] production via the thermochemical [[Sulfur-iodine cycle|iodine-sulfur]] process. It would also be [[Passive nuclear safety|passively safe]].

The planned construction of the first VHTR, the South African PBMR ([[pebble bed modular reactor]]), lost government funding in February, 2010.<ref>[http://www.powergenworldwide.com/index/display/articledisplay/6322207443/articles/power-engineering-international/volume-18/Issue_3/regulars/world-news/INTERNATIONAL.html South Africa to stop funding Pebble Bed nuclear reactor] {{webarchive|url=https://web.archive.org/web/20100909172743/http://www.powergenworldwide.com/index/display/articledisplay/6322207443/articles/power-engineering-international/volume-18/Issue_3/regulars/world-news/INTERNATIONAL.html |date=2010-09-09 }}</ref> A pronounced increase of costs and concerns about possible unexpected technical problems had discouraged potential investors and customers.

The [[People's Republic of China]] began construction of a 200-MW High Temperature Pebble bed reactor in 2012 as a successor to its [[HTR-10]].<ref>{{cite web|url=http://www.nucnet.org/all-the-news/2013/01/07/china-begins-construction-of-first-generation-iv-htr-pm-unit|title=China Begins Construction Of First Generation IV HTR-PM Unit|first=Central Office, NucNet a.s.b.l., Brussels,|last=Belgium|website=www.nucnet.org}}</ref>

Also in 2012, as part of the [[Next Generation Nuclear Plant]] competition, [[Idaho National Laboratory]] approved a design similar to [[Areva]]'s prismatic block [https://web.archive.org/web/20150722041246/http://us.areva.com/EN/home-3225/areva-inc-areva-htgr.html Antares reactor] as the chosen [[HTGR]] to be deployed as a prototype by 2021. It was in competition with [[General Atomics]]' [[Gas turbine modular helium reactor]] and [[Westinghouse Electric Company|Westinghouse]]'s [[Pebble Bed Modular Reactor]].<ref name="World nuclear news">{{cite web|url=http://www.world-nuclear-news.org/NN-Areva_modular_reactor_selected_for_NGNP_development-1502124.html|title=INL approves Antares design}}</ref>

[[X-energy]] was awarded a five-year $53M U.S. Department of Energy Advanced Reactor Concept Cooperative Agreement award to advance elements of their reactor development.<ref>{{cite web|url=https://www.x-energy.com/doe-partnership|title=x-energy - DOE Partnership|website=x-energy}}</ref>
The [[X-energy#Reactor Design|Xe-100]] is a pebble-bed modular reactor and will generate 200-MWt and approximately 76-MWe. The standard Xe-100 "four-pack" plant generates approximately 300-MWe and will fit on as few as 13 acres. All of the components for the Xe-100 will be road-transportable, and will be installed, rather than constructed, at the project site to streamline construction.<ref name="X-energy">{{cite web|url=https://www.x-energy.com/|title=x-energy|website=x-energy}}</ref>

==== Molten-salt reactor (MSR) ====
[[File:Molten Salt Reactor.svg|right|thumb|Molten Salt Reactor (MSR)]]
{{Main article|Molten salt reactor}}
{{see also|Liquid fluoride thorium reactor}}
A '''molten salt reactor'''<ref name="Roadmap"/> is a type of [[nuclear reactor]] where the primary [[coolant]], or even the fuel itself is a molten salt mixture. There have been many designs put forward for this type of reactor and a few prototypes built. The early concepts and many current ones rely on [[nuclear fuel]], perhaps [[uranium tetrafluoride]] (UF4) or [[thorium tetrafluoride]] (ThF4), dissolved in molten [[fluoride]] salt. The fluid would reach [[Nuclear reactor physics#Criticality|criticality]] by flowing into a core where [[graphite]] would serve as the [[neutron moderator|moderator]]. Many current concepts rely on fuel that is dispersed in a graphite matrix with the molten salt providing low pressure, high temperature cooling.

The Gen IV MSR is more accurately termed an [[epithermal neutron|epithermal reactor]] than a thermal reactor due to the average speed of the neutrons that would cause the fission events within its fuel being faster than [[thermal neutron]]s.<ref>{{cite web |url=https://inlportal.inl.gov/portal/server.pt?open=514&objID=1361&parentname=CommunityPage&parentid=10&mode=2&in_hi_userid=200&cached=true |title=Idaho National Laboratory detailing some current efforts at developing Gen. IV reactors}}</ref>

The principle of a MSR can be used for thermal, epithermal and fast reactors. Since 2005 the focus has moved towards a fast spectrum MSR (MSFR).<ref>H. Boussier, S. Delpech, V. Ghetta et Al. : The Molten Salt Reactor (MSR) in Generation IV: Overview and Perspectives, GIF SYMPOSIUM PROCEEDINGS/2012 ANNUAL REPORT, NEA No. 7141, pp95 [https://www.gen-4.org/gif/jcms/c_44720/annual-reports]
</ref>

While most MSR designs being pursued are largely derived from the 1960s [[Molten-Salt Reactor Experiment]] (MSRE), variants of molten salt technology include the conceptual ''[[Dual fluid reactor]]'' which is being designed with lead as a cooling medium but molten salt fuel, commonly as the metal chloride e.g. [[Plutonium(III) chloride]], to aid in greater "nuclear waste" closed-fuel cycle capabilities.
Other notable approaches differing substantially from MSRE include the ''[[Stable Salt Reactor]]'' (SSR) concept promoted by MOLTEX, which encases the molten salt in hundreds of the common solid [[fuel rod]]s that are already well established in the nuclear industry. This latter British design was found to be the most competitive for [[Small modular reactor]] development by a British-based consultancy firm ''Energy Process Development'' in 2015.<ref>{{cite web|url=http://www.daretothink.org/europe-moltex-stable-salt-reactor/|title=Europe: Moltex' Stable Salt Reactor|date=20 April 2015|publisher=}}</ref><ref>{{cite web|url=http://analysis.nuclearenergyinsider.com/moltex-energy-sees-uk-canada-smr-licensing-springboard-asia|title=Moltex Energy sees UK, Canada SMR licensing as springboard to Asia - Nuclear Energy Insider|website=analysis.nuclearenergyinsider.com}}</ref>

Another notable feature of the MSR is the possibility of a [[Thermal-neutron reactor|thermal spectrum]] nuclear [[Nuclear fuel cycle#Fuel cycles|waste-burner]]. Conventionally only fast spectrum reactors have been considered viable for [[Nuclear fuel cycle#Minor actinides recycling|utilization or reduction]] of the [[Spent nuclear fuel|spent nuclear stockpiles]]. The conceptual viability of a thermal waste-burner was first shown in a whitepaper by [[Seaborg Technologies]] spring 2015.<ref name="Seaborg Whitepaper 2015">{{cite web|url=https://seaborg.dk/s/Seaborg-whitepaper-2015.pdf|title=Thermal MSR waste burner benchmark}}</ref> Thermal waste-burning was achieved by replacing a fraction of the [[uranium]] in the spent nuclear fuel with [[thorium]]. The net production rate of [[transuranium element]] (e.g. [[plutonium]] and [[americium]]) is reduced below the consumption rate, thus reducing the magnitude of the [[Radioactive waste|nuclear storage problem]], without the [[nuclear proliferation]] concerns and other [[Fast-neutron reactor#Disadvantages|technical issues]] associated with a [[Fast-neutron reactor|fast reactor]].

==== Supercritical-water-cooled reactor (SCWR) ====
[[File:Supercritical-Water-Cooled Reactor.svg|right|thumb|Supercritical-Water-Cooled Reactor (SCWR)]]
{{Main article|Supercritical water reactor}}
The '''supercritical water reactor''' (SCWR)<ref name="Roadmap"/> is a [[reduced moderation water reactor]] concept that, due to the average speed of the neutrons that would cause the fission events within the fuel being faster than [[thermal neutron]]s, it is more accurately termed an [[epithermal neutron|epithermal reactor]] than a thermal reactor. It uses [[supercritical fluid|supercritical water]] as the working fluid. SCWRs are basically [[light water reactor]]s (LWR) operating at higher pressure and temperatures with a direct, once-through heat exchange cycle. As most commonly envisioned, it would operate on a direct cycle, much like a boiling water reactor ([[BWR]]), but since it uses supercritical water (not to be confused with [[Critical mass (nuclear)|critical mass]]) as the working fluid, it would have only one water phase present, which makes the supercritical heat exchange method more similar to a pressurized water reactor ([[Pressurized water reactor|PWR]]). It could operate at much higher temperatures than both current PWRs and BWRs.

Supercritical water-cooled reactors (SCWRs) are promising advanced nuclear systems because of their high [[thermal efficiency]] (i.e., about 45% vs. about 33% efficiency for current LWRs) and considerable plant simplification.

The main mission of the SCWR is generation of low-cost [[electricity]]. It is built upon two proven technologies, LWRs, which are the most commonly deployed power generating reactors in the world, and superheated [[fossil fuel]] fired [[boiler]]s, a large number of which are also in use around the world. The SCWR concept is being investigated by 32 organizations in 13 countries.{{citation needed|date=October 2012}}

Because SCWRs are water reactors they share the steam explosion and radioactive steam release hazards of BWRs and LWRs as well as the need for extremely expensive heavy duty pressure vessels, pipes, valves, and pumps. These shared problems are inherently more severe for SCWRs due to operation at higher temperatures.

A SCWR Design under development is the [[VVER]]-1700/393 (VVER-SCWR or VVER-SKD) — a Russian Supercritical-water-cooled reactor with double-inlet-core and a [[breeder reactor|breeding ratio]] of 0.95.<ref name="powertecrussia.com">{{cite web |url=http://www.powertecrussia.com/blog/tag/nuclear-power/ |title=Technology Developments & Plant Efficiency for the Russian Nuclear Power Generation Market Wednesday |date=March 24, 2010}}</ref>

=== Fast reactors ===
A [[Fast-neutron reactor|fast reactor]] directly uses the fast neutrons emitted by fission, without moderation. Unlike thermal neutron reactors, fast neutron reactors can be configured to "'''burn'''", or fission, all [[actinides]], and given enough time, therefore drastically reduce the actinides fraction in [[spent nuclear fuel]] produced by the present world fleet of thermal neutron [[light water reactor]]s, thus closing the [[nuclear fuel cycle]]. Alternatively, if configured differently, they can also [[breeder reactor|'''breed''']] more actinide fuel than they consume.

==== Gas-cooled fast reactor (GFR) ====
[[File:Gas-Cooled Fast Reactor Schemata.svg|right|thumb|Gas-Cooled Fast Reactor (GFR)]]
{{Main article|Gas-cooled fast reactor}}
The '''gas-cooled fast reactor''' (GFR)<ref name="Roadmap"/> system features a fast-neutron spectrum and closed fuel cycle for efficient conversion of [[Fertile material|fertile uranium]] and management of actinides. The reactor is [[helium]]-cooled and with an outlet temperature of 850 °C it is an evolution of the [[very-high-temperature reactor]] (VHTR) to a more sustainable fuel cycle. It will use a direct [[Brayton cycle]] [[Closed-cycle gas turbine|gas turbine]] for high thermal efficiency. Several fuel forms are being considered for their potential to operate at very high temperatures and to ensure an excellent retention of [[Nuclear fission|fission]] products: composite [[ceramic]] fuel, advanced fuel particles, or ceramic clad elements of actinide compounds. Core configurations are being considered based on pin- or plate-based fuel assemblies or prismatic blocks.

The European Sustainable Nuclear Industrial Initiative is funding three Generation IV reactor systems, one of which is a gas-cooled fast reactor, called ''Allegro'', 100 MW(t), which will be built in a central or eastern European country with construction expected to begin in 2018.<ref name="euronuclear.org">{{cite web|url=https://www.euronuclear.org/1-information/news/Gen-IV.htm |title=The European Sustainable Nuclear Industrial Initiative (ESNII) will support three Generation IV reactor systems: a sodium-cooled fast reactor, or SFR, called ''Astrid'' that is proposed by France; a gas-cooled fast reactor, GFR, called ''Allegro'' supported by central and eastern Europe; and a lead-cooled fast reactor, LFR, technology pilot called ''Myrrha'' that is proposed by Belgium |deadurl=yes |archiveurl=https://web.archive.org/web/20131009042600/http://euronuclear.org/1-information/news/Gen-IV.htm |archivedate=2013-10-09 |df= }}</ref> The central European [[Visegrád Group]] are committed to pursuing the technology.<ref>{{cite web |url=http://www.alphagalileo.org/ViewItem.aspx?ItemId=133111&CultureCode=en |title=The V4G4 Centre of Excellence for performing joint research, development and innovation in the field of Generation-4 (G4) nuclear reactors have been established. 20 July 2013 National Center for Nuclear Research (NCBJ)}}</ref> In 2013 German, British, and French institutes finished a 3-year collaboration study on the follow on industrial scale design, known as ''GoFastR''.<ref>{{cite web|url=http://www.ist-world.org/ProjectDetails.aspx?ProjectId=5cb8f3f283574cc6b2bdbf72533172d8 |title=the European Gas cooled Fast Reactor |deadurl=yes |archiveurl=https://web.archive.org/web/20131213091046/http://www.ist-world.org/ProjectDetails.aspx?ProjectId=5cb8f3f283574cc6b2bdbf72533172d8 |archivedate=2013-12-13 |df= }}</ref> They were funded by the EU's 7th FWP [[framework programme]], with the goal of making a sustainable VHTR.<ref>{{cite web |url=http://www.2020-horizon.com/GOFASTR-European-Gas-Cooled-Fast-Reactor%28GOFASTR%29-s312.html |title=The GOFASTR research program}}</ref>

==== Sodium-cooled fast reactor (SFR) ====
[[File:Sodium-Cooled Fast Reactor Schemata.svg|right|thumb|Pool design Sodium-Cooled Fast Reactor (SFR)]]
{{Main article|Sodium-cooled fast reactor}}
{{see also|Prototype Fast Breeder Reactor|Experimental Breeder Reactor II|S-PRISM|Toshiba 4S|CFR-600}}

The two largest commercial sodium cooled fast reactors are both in Russia, the [[BN-600]] and the recently completed [[BN-800]](800 MW). The largest ever operated was the [[Superphenix]] reactor at over 1200 MW of electrical output, successfully operating for a number of years in France before being decommissioned in 1996. In India, the [[Fast Breeder Test Reactor]] reached criticality in October 1985. In September 2002, fuel burn-up in the FBTR for the first time reached the 100,000 megawatt-days per metric ton uranium (MWd/MTU) mark. This is considered an important milestone in Indian breeder reactor technology. Using the experience gained from the operation of the FBTR, the [[Prototype Fast Breeder Reactor]], a 500 MWe Sodium cooled fast reactor is being built at a cost of INR 5,677 crores (~US$900 million) and is expected to be critical by June 2019. The PFBR will be followed by six more Commercial Fast Breeder Reactors (CFBRs) of 600 MWe each.

The Gen IV SFR<ref name="Roadmap"/> is a project that builds on two closely related existing projects, the liquid metal [[Breeder reactor#Fast breeder reactor|fast breeder reactor]] and the [[integral fast reactor]].

The goals are to increase the efficiency of uranium usage by [[breeder reactor|breeding]] plutonium and eliminating the need for [[transuranic]] isotopes ever to leave the site. The reactor design uses an unmoderated core running on [[fast neutron]]s, designed to allow any transuranic isotope to be consumed (and in some cases used as fuel). In addition to the benefits of removing the long [[half-life]] transuranics from the waste cycle, the SFR fuel expands when the reactor overheats, and the chain reaction automatically slows down. In this manner, it is passively safe.<ref>{{cite web |url=http://www.ne.anl.gov/About/hn/logos-winter02-psr.shtml|title=Passively safe reactors rely on nature to keep them cool|author=David Baurac}}</ref>

The SFR reactor concept is cooled by liquid [[sodium]] and fueled by a metallic alloy of uranium and [[plutonium]] or [[spent nuclear fuel]], the "nuclear waste" of [[light water reactor]]s. The SFR fuel is contained in steel cladding with liquid sodium filling in the space between the clad elements which make up the fuel assembly. One of the design challenges of an SFR is the risks of handling sodium, which reacts explosively if it comes into contact with water. However, the use of liquid metal instead of water as coolant allows the system to work at atmospheric pressure, reducing the risk of leakage.

[[File:Ifr concept.jpg|thumb|375px|The sustainable fuel-cycle proposed in the 1990s [[Integral fast reactor]] concept (color), an animation of the [[pyroprocessing]] technology is also available.<ref>{{cite web |url=https://www.youtube.com/watch?v=cBThTwFhRlA |title=Historical video about the Integral Fast Reactor (IFR) concept. Uploaded by - Nuclear Engineering at Argonne}}</ref>]]
[[File:IFR concept.png|thumb|375px|IFR concept (Black and White with clearer text)]]

The European Sustainable Nuclear Industrial Initiative is funding three Generation IV reactor systems, one of which is a sodium-cooled fast reactor, called ''[[ASTRID (reactor)|ASTRID]]'', Advanced Sodium Technical Reactor for Industrial Demonstration, [[Areva]], [[Commissariat à l'énergie atomique et aux énergies alternatives|CEA]] and [[Électricité de France|EDF]] are leading the design with British collaboration.<ref>{{cite web |url=http://www.power-eng.com/articles/2010/11/areva--cea-secure.html |title=Areva, CEA secure EUR650m funding to develop ASTRID sodium-cooled Generation IV reactor 11/11/2010}}</ref><ref>{{cite web |url=http://www.powermag.com/uk-and-france-sign-landmark-civil-nuclear-cooperation-agreement/ |title=UK and France Sign Landmark Civil Nuclear Cooperation Agreement 02/22/2012 . POWERnews}}</ref> Astrid will be rated about 600 MWe and is proposed to be built in France, near to the [[Phénix]] reactor. A final decision in construction is to be made in 2019<ref name="euronuclear.org"/>

The [[China|PRC]]'s first commercial-scale, 800 MWe, fast neutron reactor, to be situated near [[Sanming]] in [[Fujian province]] will be a SFR. In 2009 an agreement was signed that would entail the Russian [[BN-800 reactor]] design to be sold to the PRC once it is completed, this would be the first time commercial-scale fast neutron reactors have ever been exported.<ref>{{cite web |url=http://www.world-nuclear-news.org/C-Joint_venture_launched_for_Chinese_fast_reactor-3004104.html |title=Joint venture launched for Chinese fast reactor}}</ref> The BN-800 reactor became operational in 2014.

Numerous progenitors of the Gen IV SFR exist around the world, with the 400 MWe [[Fast Flux Test Facility]] operated successfully for ten years at the Hanford site in Washington State.

The 20 MWe [[EBR II]] operated successfully for over thirty years at the Idaho National Laboratory, until it was shut down in 1994.

GE Hitachi's [[PRISM (reactor)|PRISM]] reactor is a modernized and commercial implementation of the technology developed for the Integral Fast Reactor(IFR), developed by [[Argonne National Laboratory]] between 1984 and 1994. With the primary purpose of PRISM differing in the focus on burning up [[spent nuclear fuel]] from other reactors, rather than [[breeder reactor|breeding]] new fuel. Presented as an alternative to burying the spent fuel/waste, the design reduces the half lives of the fissionable elements present in spent nuclear fuel while generating electricity largely as a by-product.

==== Lead-cooled fast reactor (LFR) ====
[[File:Lead-Cooled Fast Reactor Schemata.svg|right|thumb|Lead-Cooled Fast Reactor (LFR)]]
{{Main article|Lead-cooled fast reactor}}
{{See also|MYRRHA}}
The '''lead-cooled fast reactor'''<ref name="Roadmap">{{cite journal|year=2002 |title=A Technology Roadmap for Generation IV Nuclear Energy Systems |last=US DOE Nuclear Energy Research Advisory Committee |volume=GIF-002-00 |url=http://nuclear.energy.gov/genIV/documents/gen_iv_roadmap.pdf |deadurl=yes |archiveurl=https://web.archive.org/web/20071129121214/http://nuclear.energy.gov/genIV/documents/gen_iv_roadmap.pdf |archivedate=2007-11-29 |df= }}</ref> features a fast-neutron-spectrum [[lead]] or [[lead]]/[[bismuth]] [[eutectic]] ([[Lead-bismuth eutectic|LBE]]) liquid-metal-cooled reactor with a closed [[Nuclear fuel cycle|fuel cycle]]. Options include a range of plant ratings, including a "battery" of 50 to 150 MW of electricity that features a very long refueling interval, a modular system rated at 300 to 400 MW, and a large monolithic plant option at 1,200 MW (The term ''battery'' refers to the long-life, factory-fabricated core, not to any provision for electrochemical energy conversion). The fuel is metal or nitride-based containing [[Fertile material|fertile uranium]] and [[transuranic]]s. The LFR is cooled by natural [[convection]] with a reactor outlet coolant temperature of 550 °C, possibly ranging up to 800 °C with advanced materials. The higher temperature enables the production of [[Thermochemical cycle|hydrogen by thermochemical processes]].

The European Sustainable Nuclear Industrial Initiative is funding three Generation IV reactor systems, one of which is a lead-cooled fast reactor that is also an [[Subcritical reactor|accelerator-driven sub-critical]] reactor, called ''[[MYRRHA]]'', 100 MW(t), which will be built in [[Belgium]] with construction expected to begin after 2014 and the industrial scale version, known as ''Alfred'', slated to be constructed sometime after 2017. A reduced-power model of Myrrha called ''Guinevere'' was started up at [[Mol, Belgium|Mol]] in March 2009.<ref name="euronuclear.org"/> In 2012 the research team reported that Guinevere was operational.<ref>{{cite news|last1=Hellemans|first1=Alexander|title=Reactor-Accelerator Hybrid Achieves Successful Test Run|url=http://news.sciencemag.org/physics/2012/01/reactor-accelerator-hybrid-achieves-successful-test-run|accessdate=29 December 2014|work=Science Insider|date=12 January 2012}}</ref>

Two other lead-cooled fast reactors under development are the SVBR-100, a modular 100 MWe lead-bismuth cooled fast neutron reactor concept designed by OKB [[Gidropress]] in Russia and the [[BREST (Reactor)|BREST-OD-300]] (Lead-cooled fast reactor) 300 MWe, to be developed after the SVBR-100, and built over 2016-20, it will dispense with the [[Uranium-238|fertile blanket]] around the core and will supersede the sodium cooled [[BN-600 reactor]] design, to purportedly give enhanced proliferation resistance.<ref name="powertecrussia.com"/>

== Advantages and disadvantages ==
Relative to current nuclear power plant technology, the claimed benefits for 4th generation reactors include:
* Nuclear waste that remains radioactive for a few centuries instead of millennia<ref>{{cite web |title=Strategies to Address Global Warming |url=http://www.columbia.edu/~jeh1/mailings/2009/20090713_Strategies.pdf}}</ref>
* 100–300 times more energy yield from the same amount of nuclear fuel<ref>{{cite web |title=4th Generation Nuclear Power |url=http://www.ossfoundation.us/projects/energy/nuclear}}</ref>
* Broader range of fuels, and even unencapsulated raw fuels (non-pebble [[Molten Salt Reactor|MSR]], [[Liquid fluoride thorium reactor|LFTR]]).
* In some reactors, the ability to consume existing nuclear waste in the production of electricity, that is, a Closed [[nuclear fuel cycle]]. This strengthens the argument to deem [[nuclear power as renewable energy]].
* Improved operating safety features, such as (depending on design) avoidance of pressurized operation, automatic passive (unpowered, uncommanded) reactor shutdown, avoidance of water cooling and the associated risks of loss of water (leaks or boiling) and hydrogen generation/explosion and contamination of coolant water.

Nuclear reactors do not emit CO2 during operation, although like all [[low carbon power]] sources, the mining and construction phase can result in CO2 emissions, if energy sources which are not carbon neutral (such as fossil fuels), or CO2 emitting cements are used during the construction process.
A 2012 [[Yale University]] review published in the Journal of Industrial Ecology analyzing {{CO2}} [[life cycle assessment]] (LCA) emissions from [[nuclear power]] determined that:<ref name="Warner + Heath, JoIE">{{cite journal |doi=10.1111/j.1530-9290.2012.00472.x|title=Life Cycle Greenhouse Gas Emissions of Nuclear Electricity Generation|journal=Journal of Industrial Ecology|volume=16|pages=S73–S92|year=2012|last1=Warner|first1=Ethan S|last2=Heath|first2=Garvin A}}</ref>
{{Quote|The collective LCA literature indicates that life cycle [[Greenhouse gas|GHG]] [greenhouse gas] emissions from nuclear power are only a fraction of traditional fossil sources and comparable to renewable technologies.}}
Although the paper primarily dealt with data from [[Generation II reactor]]s, and did not analyze the {{CO2}} emissions by 2050 of the presently under construction [[Generation III reactor]]s, it did summarize the Life Cycle Assessment findings of in development reactor technologies.{{Quote|FBRs ['[[Fast Breeder Reactor]]s'] have been evaluated in the LCA literature. The limited literature that evaluates this potential future technology reports [[median]] life cycle GHG emissions... similar to or lower than LWRs [Gen II [[light water reactor]]s] and purports to consume little or no [[uranium market|uranium ore]].}}

A specific risk of the sodium-cooled fast reactor is related to using metallic sodium as a coolant. In case of a breach, sodium explosively reacts with water. Fixing breaches may also prove dangerous, as the cheapest noble gas [[argon]] is also used to prevent sodium oxidation. Argon, like helium, can displace oxygen in the air and can pose [[hypoxia (environmental)|hypoxia]] concerns, so workers may be exposed to this additional risk. This is a pertinent problem as demonstrated by the events at the [[LMFBR|loop type]] [[Monju Nuclear Power Plant|Prototype Fast Breeder Reactor Monju]] at Tsuruga, Japan.<ref>{{cite news |title=Japan Strains to Fix a Reactor Damaged Before Quake |url=https://www.nytimes.com/2011/06/18/world/asia/18japan.html | work=The New York Times | first=Hiroko |last=Tabuchi |date=17 June 2011}}</ref>
Using lead or molten salts mitigates this problem by making the coolant less reactive and allowing a high freezing temperature and low pressure in case of a leak. Disadvantages of lead compared to sodium are much higher viscosity, much higher density, lower heat capacity, and more radioactive neutron activation products.

In many cases, there is already a large amount of experience built up with numerous proof of concept Gen IV designs. For example, the reactors at [[Fort St. Vrain Generating Station]] and [[HTR-10]] are similar to the proposed Gen IV [[VHTR]] designs, and the [[LMFBR|pool type]] [[EBR-II]], [[Phénix]] and [[BN-600]] reactor are similar to the proposed pool type Gen IV Sodium Cooled Fast reactors being designed.

== Table of designs ==

{| class=wikitable
|+ Summary of designs for generation IV reactors<ref>{{cite web |title=GIF R&D Outlook for Generation IV Nuclear Energy Systems |date=21 August 2009 |url=https://www.gen-4.org/gif/upload/docs/application/pdf/2013-09/gif_rd_outlook_for_generation_iv_nuclear_energy_systems.pdf |accessdate=August 30, 2018}}</ref>
|-
! System
! Neutron Spectrum
! Coolant
! Temperature (°C)
! Fuel Cycle
! Size (MW)
!Example developers
|-
| [[Very-high-temperature reactor|VHTR]]
| Thermal
| Helium
| 900–1000
| Open
| 250–300
|[[Japan Atomic Energy Agency|JAEA]] ([[High-temperature engineering test reactor|HTTR]]), [[Tsinghua University]] ([[HTR-10]]), [[X-energy]]<ref name="energy.gov">{{cite web|title=Energy Department Announces New Investments in Advanced Nuclear Power Reactors…|url=https://www.energy.gov/articles/energy-department-announces-new-investments-advanced-nuclear-power-reactors-help-meet|website=[[United States Department of Energy|US Department of Energy]]|accessdate=16 January 2016}}</ref>
|-
| [[Sodium-cooled fast reactor|SFR]]
| Fast
| Sodium
| 550
| Closed
| 30–150, 300–1500, 1000–2000
|[[TerraPower]] ([[Traveling wave reactor|TWR]]), [[Toshiba]] ([[Toshiba 4S|4S]]), [[GE Hitachi Nuclear Energy]] ([[PRISM (reactor)|PRISM]])
|-
| [[Supercritical water reactor|SCWR]]
| Thermal or fast
| Water
| 510–625
| Open or closed
| 300–700, 1000–1500
|
|-
| [[Gas-cooled fast reactor|GFR]]
| Fast
| Helium
| 850
| Closed
| 1200
|[[Energy Multiplier Module]]
|-
| [[Lead-cooled fast reactor|LFR]]
| Fast
| Lead
| 480–800
| Closed
| 20–180, 300–1200, 600–1000
|
|-
| [[Molten salt reactor|MSR]]
| Fast or thermal
| Fluoride or chloride salts
| 700–800
| Closed
| 250, 1000
|[[Seaborg Technologies]], [[TerraPower]], [[Stable Salt Reactor|Moltex Energy]], [[Flibe Energy]] ([[Liquid fluoride thorium reactor|LFTR]]), [[Transatomic Power]], Thorium Tech Solution ([[Fuji Molten Salt Reactor|FUJI MSR]]), Terrestrial Energy ([[IMSR]]), [[Southern Company Services|Southern Company]]<ref name="energy.gov"/>
|-
| [[Dual fluid reactor|DFR]]
| Fast
| Lead
| 1000
| Closed
| 500–1500
| Institute for Solid-State Nuclear Physics<ref name=ifk>{{cite web |url=https://festkoerper-kernphysik.de/dfr.pdf |title=Dual Fluid Reactor - IFK |date=2013-06-16 |website=festkoerper-kernphysik.de |publisher= Institut für Festkörper-Kernphysik |format=PDF |location=Berlin, Germany |access-date=2017-08-28}}</ref>
|}

== See also ==
{{portal|Energy|Nuclear technology}}
{{colbegin}}
* [[Nuclear reactor]]
* [[Nuclear material]]
* [[Nuclear physics]]
* [[List of reactor types#Reactor types|List of reactor types]]
* [[Generation II reactor]]
* [[Generation III reactor]]
* [[Integral Fast Reactor]]
* [[Liquid fluoride thorium reactor]]
* [[Breeder reactor]]
* [[Small modular reactor]]
* [[List of nuclear reactors]]
{{colend}}

==References==
{{Reflist|30em}}

== External links ==
* [https://inlportal.inl.gov/portal/server.pt?open=514&objID=1361&parentname=CommunityPage&parentid=10&mode=2&in_hi_userid=200&cached=true Article from Idaho National Laboratory detailing some current efforts at developing Gen. IV reactors.]
* [http://www.gen-4.org/ Generation IV International Forum (GIF)]
* [https://web.archive.org/web/20070205115654/http://nuclear.energy.gov/genIV/neGenIV1.html U.S. Department of Energy Office of Nuclear Energy, Science and Technology]
* [https://web.archive.org/web/20060512033030/http://www.engr.utk.edu/nuclear/colloquia/slides/Gen%20IV%20U-Tenn%20Presentation.pdf Gen IV presentation]
* [http://www.ecology.at/ecology/files/pr577_1.pdf Science or Fiction - Is there a Future for Nuclear?] (Nov. 2007) - A publication from the Austrian [[Ecology Institute (Austria)|Ecology Institute]] about 'Generation IV' and Fusion reactors.
* {{cite web |url=http://memagazine.asme.org/Articles/2011/December/Nuclear_Power_After_Fukushima.cfm |title=Nuclear Power After Fukushima |author=Gail H. Marcus |date=December 2011 |website=Mechanical Engineering (the magazine of [[ASME]]) |accessdate=23 January 2012}} "In the wake of a severe plant accident, advanced reactor designs are getting renewed attention."
* [http://www.itheo.org/ International Thorium Energy Organisation - www.IThEO.org]
* [http://www.ithec.org/ International Thorium Energy Committee - iThEC]

{{Nuclear fission reactors}}

[[Category:Nuclear power reactor types]]
[[Category:Idaho National Laboratory]]

Benutzer:Snackroeg/Kernreaktoren der Generation 5

2018-09-29T15:32:16Z

Boundarylayer:

{{update|date=October 2017}}
[[File:GenIVRoadmap-en.svg|thumb|480px|Nuclear Energy Systems Deployable no later than 2030 and offering significant advances in sustainability, safety and reliability, and economics]]

'''Generation IV reactors''' ('''Gen IV''') are a set of [[nuclear reactor]] designs currently being researched for commercial applications by the Generation IV International Forum, with [[Technology readiness level]]s varying between the level requiring a demonstration, to economical competitive implementation.<ref name=Locatelli>{{Cite journal|last=Locatelli|first=Giorgio|last2=Mancini|first2=Mauro|last3=Todeschini|first3=Nicola|date=2013-10-01|title=Generation IV nuclear reactors: Current status and future prospects|journal=Energy Policy|volume=61|pages=1503–1520|doi=10.1016/j.enpol.2013.06.101}}</ref> They are motivated by a variety of goals including improved safety, sustainability, efficiency, and cost.

The most developed Gen IV reactor design, the [[sodium fast reactor]], has received the greatest share of funding over the years with a number of demonstration facilities operated, the principle Gen IV aspect of the design, relates in largest part to the development of a sustainable closed [[Nuclear_fuel_cycle#Plutonium_cycle|fuel cycle]] for the reactor. Amongst nuclear engineers the [[molten-salt reactor]], the least developed and funded technology, is considered as potentially having the greatest [[Passive nuclear safety|inherent safety]] of the six models.<ref>{{cite web|url=https://www.scientificamerican.com/article/can-sodium-save-nuclear-power/|title=Can Sodium Save Nuclear Power?|publisher=}}</ref><ref>{{cite journal |last1=Moir |first1=Ralph |last2=Teller |first2=Edward |year=2005 |title=Thorium-Fueled Underground Power Plant Based on Molten Salt Technology |journal=Nuclear Technology |volume=151 |issue=3 |pages=334–340 |url=http://www.new.ans.org/pubs/journals/nt/a_3655 |accessdate=March 22, 2012 }}</ref> While the [[hydrogen economy]], the [[high temperature electrolysis|thermochemical production]] of hydrogen to synthesize [[Carbon-neutral fuel]]s, is deemed as strengthening the economic case for the two most [[Closed-cycle gas turbine|thermodynamically efficient]] models, the [[Very-high-temperature reactor|high temperature reactor]] designs.<ref name=Locatelli/>

The majority of the 6 designs are generally not expected to be available for commercial construction until 2020–30.<ref name="Generation IV">{{cite web|url=http://www.world-nuclear.org/info/Nuclear-Fuel-Cycle/Power-Reactors/Generation-IV-Nuclear-Reactors/|title=Generation IV Nuclear Reactors: WNA - World Nuclear Association|website=www.world-nuclear.org}}</ref> Presently the majority of reactors in operation around the world are considered [[Generation II reactor|second generation reactor]] systems, as the vast majority of the [[Nuclear reactor#Classification by generation|first generation]] systems were retired some time ago, and there are only a dozen or so [[Generation III reactor]]s in operation as of 2014.
[[Nuclear reactor#Generation V+ reactors|Generation V reactors]] refer to reactors that are purely theoretical and are therefore not yet considered feasible in the short term, resulting in limited [[R&D]] funding.

== History ==
The Generation IV International Forum (GIF) is "a co-operative international endeavour which was set up to carry out the research and development needed to establish the feasibility and performance capabilities of the next generation nuclear energy systems."<ref>{{Cite web|url=https://www.gen-4.org/gif/jcms/c_9260/public|title=GIF Portal - Home - Public|website=www.gen-4.org|access-date=2016-07-25}}</ref> It was founded in 2001. Currently active members of the Generation IV International Forum (GIF) include: [[Australia]], [[Canada]], [[China]], the [[European Atomic Energy Community]] (Euratom), [[France]], [[Japan]], [[Russia]], [[South Africa]], [[South Korea]], [[Switzerland]], and the [[United States]]. The non-active members are [[Argentina]], [[Brazil]], and the [[United Kingdom]].<ref name="gen-4">{{cite web|url=https://www.gen-4.org/gif/jcms/c_9492/members|title=GIF Membership|website=gen-4.org|accessdate=28 October 2014}}</ref> Switzerland joined in 2002, Euratom in 2003, and China and Russia in 2006. The remaining countries (excluding Australia) were founding members.<ref name="gen-4" />

The 36th GIF meeting in [[Brussels]] was held in November 2013.<ref>{{cite web|url=https://www.energy.gov/ne/articles/generation-iv-international-forum-updates-technology-roadmap-and-builds-future|title=generation IV international forum updates technology roadmap and builds future. DOE}}</ref><ref>{{cite web|url=http://events.r20.constantcontact.com/register/event?llr=mscrkjkab&oeidk=a07e7melf609716b2c6 |title=The Generation IV international forum holds their 36th meeting on Monday 18th Nov 2013 in Brussels }}{{dead link|date=January 2017 |bot=InternetArchiveBot |fix-attempted=yes }}</ref> The ''Technology Roadmap Update for Generation IV Nuclear Energy Systems'' was published in January 2014 which details R&D objectives for the next decade.<ref>{{cite web|url=https://www.gen-4.org/gif/upload/docs/application/pdf/2014-03/gif-tru2014.pdf|archive-url=https://web.archive.org/web/20140625102915/https://www.gen-4.org/gif/upload/docs/application/pdf/2014-03/gif-tru2014.pdf|dead-url=yes|archive-date=25 June 2014|title=Wayback Machine|date=25 June 2014|publisher=}}</ref> A breakdown of the reactor designs being researched by each forum member has been made available.<ref>{{cite web|url=https://www.gen-4.org/gif/upload/docs/application/pdf/2014-03/gif_overview_presentation_v9_final3_web.pdf|archive-url=https://web.archive.org/web/20140708023538/https://www.gen-4.org/gif/upload/docs/application/pdf/2014-03/gif_overview_presentation_v9_final3_web.pdf|dead-url=yes|archive-date=8 July 2014|title=Wayback Machine|date=8 July 2014|publisher=}}</ref>

[[Nuclear power in Australia|Australia]] joined the forum in 2016.<ref>{{cite web|url=https://www.gen-4.org/gif/jcms/c_71564/australia-joins-the-generation-iv-international-forum|archiveurl=https://archive.today/20160907131656/https://www.gen-4.org/gif/jcms/c_71564/australia-joins-the-generation-iv-international-forum|deadurl=yes|title=GIF Portal - Australia joins the Generation IV International Forum|date=7 September 2016|archivedate=7 September 2016|publisher=}}</ref>

In January 2018, it was reported that "the first installation of the pressure vessel cover of the world's first Gen IV reactor" had been completed on the [[HTR-PM]].<ref>{{cite web|url=http://www.world-nuclear-news.org/NN-First-HTR-PM-vessel-head-in-place-0401185.html|title=First HTR-PM vessel head in place - World Nuclear News|website=www.world-nuclear-news.org}}</ref>

== Reactor types ==
Many reactor types were considered initially; however, the list was downsized to focus on the most promising technologies and those that could most likely meet the goals of the Gen IV initiative.<ref name="Generation IV"/> Three systems are nominally [[thermal reactor]]s and four are [[fast reactor]]s. The Very High Temperature Reactor (VHTR) is also being researched for potentially providing high quality process heat for [[thermochemical cycle|hydrogen production]]. The fast reactors offer the possibility of burning [[actinides]] to further reduce waste and of being able to "[[breeder reactor|breed more fuel]]" than they consume. These systems offer significant advances in sustainability, safety and reliability, economics, proliferation resistance (depending on perspective) and physical protection.

=== Thermal reactors ===
A [[Thermal-neutron reactor|thermal reactor]] is a [[nuclear reactor]] that uses slow or [[thermal neutrons]]. A [[neutron moderator]] is used to slow the [[neutron]]s emitted by fission to make them more likely to be captured by the fuel.

==== Very-high-temperature reactor (VHTR) ====
[[File:Very High Temperature Reactor.svg|right|thumb|Very-High-Temperature Reactor (VHTR)]]
{{Main article|Very high temperature reactor}}
{{see also|Fort St. Vrain Generating Station|High-temperature engineering test reactor|HTR-10}}
The '''very high temperature reactor''' concept uses a [[graphite]]-moderated core with a once-through [[uranium]] fuel cycle, using helium or molten salt as the [[Very high temperature reactor#Coolant|coolant]]. This reactor design envisions an outlet temperature of 1,000 °C. The reactor core can be either a prismatic-block or a [[pebble bed reactor]] design. The high temperatures enable applications such as process heat or [[hydrogen]] production via the thermochemical [[Sulfur-iodine cycle|iodine-sulfur]] process. It would also be [[Passive nuclear safety|passively safe]].

The planned construction of the first VHTR, the South African PBMR ([[pebble bed modular reactor]]), lost government funding in February, 2010.<ref>[http://www.powergenworldwide.com/index/display/articledisplay/6322207443/articles/power-engineering-international/volume-18/Issue_3/regulars/world-news/INTERNATIONAL.html South Africa to stop funding Pebble Bed nuclear reactor] {{webarchive|url=https://web.archive.org/web/20100909172743/http://www.powergenworldwide.com/index/display/articledisplay/6322207443/articles/power-engineering-international/volume-18/Issue_3/regulars/world-news/INTERNATIONAL.html |date=2010-09-09 }}</ref> A pronounced increase of costs and concerns about possible unexpected technical problems had discouraged potential investors and customers.

The [[People's Republic of China]] began construction of a 200-MW High Temperature Pebble bed reactor in 2012 as a successor to its [[HTR-10]].<ref>{{cite web|url=http://www.nucnet.org/all-the-news/2013/01/07/china-begins-construction-of-first-generation-iv-htr-pm-unit|title=China Begins Construction Of First Generation IV HTR-PM Unit|first=Central Office, NucNet a.s.b.l., Brussels,|last=Belgium|website=www.nucnet.org}}</ref>

Also in 2012, as part of the [[Next Generation Nuclear Plant]] competition, [[Idaho National Laboratory]] approved a design similar to [[Areva]]'s prismatic block [https://web.archive.org/web/20150722041246/http://us.areva.com/EN/home-3225/areva-inc-areva-htgr.html Antares reactor] as the chosen [[HTGR]] to be deployed as a prototype by 2021. It was in competition with [[General Atomics]]' [[Gas turbine modular helium reactor]] and [[Westinghouse Electric Company|Westinghouse]]'s [[Pebble Bed Modular Reactor]].<ref name="World nuclear news">{{cite web|url=http://www.world-nuclear-news.org/NN-Areva_modular_reactor_selected_for_NGNP_development-1502124.html|title=INL approves Antares design}}</ref>

[[X-energy]] was awarded a five-year $53M U.S. Department of Energy Advanced Reactor Concept Cooperative Agreement award to advance elements of their reactor development.<ref>{{cite web|url=https://www.x-energy.com/doe-partnership|title=x-energy - DOE Partnership|website=x-energy}}</ref>
The [[X-energy#Reactor Design|Xe-100]] is a pebble-bed modular reactor and will generate 200-MWt and approximately 76-MWe. The standard Xe-100 "four-pack" plant generates approximately 300-MWe and will fit on as few as 13 acres. All of the components for the Xe-100 will be road-transportable, and will be installed, rather than constructed, at the project site to streamline construction.<ref name="X-energy">{{cite web|url=https://www.x-energy.com/|title=x-energy|website=x-energy}}</ref>

==== Molten-salt reactor (MSR) ====
[[File:Molten Salt Reactor.svg|right|thumb|Molten Salt Reactor (MSR)]]
{{Main article|Molten salt reactor}}
{{see also|Liquid fluoride thorium reactor}}
A '''molten salt reactor'''<ref name="Roadmap"/> is a type of [[nuclear reactor]] where the primary [[coolant]], or even the fuel itself is a molten salt mixture. There have been many designs put forward for this type of reactor and a few prototypes built. The early concepts and many current ones rely on [[nuclear fuel]], perhaps [[uranium tetrafluoride]] (UF4) or [[thorium tetrafluoride]] (ThF4), dissolved in molten [[fluoride]] salt. The fluid would reach [[Nuclear reactor physics#Criticality|criticality]] by flowing into a core where [[graphite]] would serve as the [[neutron moderator|moderator]]. Many current concepts rely on fuel that is dispersed in a graphite matrix with the molten salt providing low pressure, high temperature cooling.

The Gen IV MSR is more accurately termed an [[epithermal neutron|epithermal reactor]] than a thermal reactor due to the average speed of the neutrons that would cause the fission events within its fuel being faster than [[thermal neutron]]s.<ref>{{cite web |url=https://inlportal.inl.gov/portal/server.pt?open=514&objID=1361&parentname=CommunityPage&parentid=10&mode=2&in_hi_userid=200&cached=true |title=Idaho National Laboratory detailing some current efforts at developing Gen. IV reactors}}</ref>

The principle of a MSR can be used for thermal, epithermal and fast reactors. Since 2005 the focus has moved towards a fast spectrum MSR (MSFR).<ref>H. Boussier, S. Delpech, V. Ghetta et Al. : The Molten Salt Reactor (MSR) in Generation IV: Overview and Perspectives, GIF SYMPOSIUM PROCEEDINGS/2012 ANNUAL REPORT, NEA No. 7141, pp95 [https://www.gen-4.org/gif/jcms/c_44720/annual-reports]
</ref>

While most MSR designs being pursued are largely derived from the 1960s [[Molten-Salt Reactor Experiment]] (MSRE), variants of molten salt technology include the conceptual ''[[Dual fluid reactor]]'' which is being designed with lead as a cooling medium but molten salt fuel, commonly as the metal chloride e.g. [[Plutonium(III) chloride]], to aid in greater "nuclear waste" closed-fuel cycle capabilities.
Other notable approaches differing substantially from MSRE include the ''[[Stable Salt Reactor]]'' (SSR) concept promoted by MOLTEX, which encases the molten salt in hundreds of the common solid [[fuel rod]]s that are already well established in the nuclear industry. This latter British design was found to be the most competitive for [[Small modular reactor]] development by a British-based consultancy firm ''Energy Process Development'' in 2015.<ref>{{cite web|url=http://www.daretothink.org/europe-moltex-stable-salt-reactor/|title=Europe: Moltex' Stable Salt Reactor|date=20 April 2015|publisher=}}</ref><ref>{{cite web|url=http://analysis.nuclearenergyinsider.com/moltex-energy-sees-uk-canada-smr-licensing-springboard-asia|title=Moltex Energy sees UK, Canada SMR licensing as springboard to Asia - Nuclear Energy Insider|website=analysis.nuclearenergyinsider.com}}</ref>

Another notable feature of the MSR is the possibility of a [[Thermal-neutron reactor|thermal spectrum]] nuclear [[Nuclear fuel cycle#Fuel cycles|waste-burner]]. Conventionally only fast spectrum reactors have been considered viable for [[Nuclear fuel cycle#Minor actinides recycling|utilization or reduction]] of the [[Spent nuclear fuel|spent nuclear stockpiles]]. The conceptual viability of a thermal waste-burner was first shown in a whitepaper by [[Seaborg Technologies]] spring 2015.<ref name="Seaborg Whitepaper 2015">{{cite web|url=https://seaborg.dk/s/Seaborg-whitepaper-2015.pdf|title=Thermal MSR waste burner benchmark}}</ref> Thermal waste-burning was achieved by replacing a fraction of the [[uranium]] in the spent nuclear fuel with [[thorium]]. The net production rate of [[transuranium element]] (e.g. [[plutonium]] and [[americium]]) is reduced below the consumption rate, thus reducing the magnitude of the [[Radioactive waste|nuclear storage problem]], without the [[nuclear proliferation]] concerns and other [[Fast-neutron reactor#Disadvantages|technical issues]] associated with a [[Fast-neutron reactor|fast reactor]].

==== Supercritical-water-cooled reactor (SCWR) ====
[[File:Supercritical-Water-Cooled Reactor.svg|right|thumb|Supercritical-Water-Cooled Reactor (SCWR)]]
{{Main article|Supercritical water reactor}}
The '''supercritical water reactor''' (SCWR)<ref name="Roadmap"/> is a [[reduced moderation water reactor]] concept that, due to the average speed of the neutrons that would cause the fission events within the fuel being faster than [[thermal neutron]]s, it is more accurately termed an [[epithermal neutron|epithermal reactor]] than a thermal reactor. It uses [[supercritical fluid|supercritical water]] as the working fluid. SCWRs are basically [[light water reactor]]s (LWR) operating at higher pressure and temperatures with a direct, once-through heat exchange cycle. As most commonly envisioned, it would operate on a direct cycle, much like a boiling water reactor ([[BWR]]), but since it uses supercritical water (not to be confused with [[Critical mass (nuclear)|critical mass]]) as the working fluid, it would have only one water phase present, which makes the supercritical heat exchange method more similar to a pressurized water reactor ([[Pressurized water reactor|PWR]]). It could operate at much higher temperatures than both current PWRs and BWRs.

Supercritical water-cooled reactors (SCWRs) are promising advanced nuclear systems because of their high [[thermal efficiency]] (i.e., about 45% vs. about 33% efficiency for current LWRs) and considerable plant simplification.

The main mission of the SCWR is generation of low-cost [[electricity]]. It is built upon two proven technologies, LWRs, which are the most commonly deployed power generating reactors in the world, and superheated [[fossil fuel]] fired [[boiler]]s, a large number of which are also in use around the world. The SCWR concept is being investigated by 32 organizations in 13 countries.{{citation needed|date=October 2012}}

Because SCWRs are water reactors they share the steam explosion and radioactive steam release hazards of BWRs and LWRs as well as the need for extremely expensive heavy duty pressure vessels, pipes, valves, and pumps. These shared problems are inherently more severe for SCWRs due to operation at higher temperatures.

A SCWR Design under development is the [[VVER]]-1700/393 (VVER-SCWR or VVER-SKD) — a Russian Supercritical-water-cooled reactor with double-inlet-core and a [[breeder reactor|breeding ratio]] of 0.95.<ref name="powertecrussia.com">{{cite web |url=http://www.powertecrussia.com/blog/tag/nuclear-power/ |title=Technology Developments & Plant Efficiency for the Russian Nuclear Power Generation Market Wednesday |date=March 24, 2010}}</ref>

=== Fast reactors ===
A [[Fast-neutron reactor|fast reactor]] directly uses the fast neutrons emitted by fission, without moderation. Unlike thermal neutron reactors, fast neutron reactors can be configured to "'''burn'''", or fission, all [[actinides]], and given enough time, therefore drastically reduce the actinides fraction in [[spent nuclear fuel]] produced by the present world fleet of thermal neutron [[light water reactor]]s, thus closing the [[nuclear fuel cycle]]. Alternatively, if configured differently, they can also [[breeder reactor|'''breed''']] more actinide fuel than they consume.

==== Gas-cooled fast reactor (GFR) ====
[[File:Gas-Cooled Fast Reactor Schemata.svg|right|thumb|Gas-Cooled Fast Reactor (GFR)]]
{{Main article|Gas-cooled fast reactor}}
The '''gas-cooled fast reactor''' (GFR)<ref name="Roadmap"/> system features a fast-neutron spectrum and closed fuel cycle for efficient conversion of [[Fertile material|fertile uranium]] and management of actinides. The reactor is [[helium]]-cooled and with an outlet temperature of 850 °C it is an evolution of the [[very-high-temperature reactor]] (VHTR) to a more sustainable fuel cycle. It will use a direct [[Brayton cycle]] [[Closed-cycle gas turbine|gas turbine]] for high thermal efficiency. Several fuel forms are being considered for their potential to operate at very high temperatures and to ensure an excellent retention of [[Nuclear fission|fission]] products: composite [[ceramic]] fuel, advanced fuel particles, or ceramic clad elements of actinide compounds. Core configurations are being considered based on pin- or plate-based fuel assemblies or prismatic blocks.

The European Sustainable Nuclear Industrial Initiative is funding three Generation IV reactor systems, one of which is a gas-cooled fast reactor, called ''Allegro'', 100 MW(t), which will be built in a central or eastern European country with construction expected to begin in 2018.<ref name="euronuclear.org">{{cite web|url=https://www.euronuclear.org/1-information/news/Gen-IV.htm |title=The European Sustainable Nuclear Industrial Initiative (ESNII) will support three Generation IV reactor systems: a sodium-cooled fast reactor, or SFR, called ''Astrid'' that is proposed by France; a gas-cooled fast reactor, GFR, called ''Allegro'' supported by central and eastern Europe; and a lead-cooled fast reactor, LFR, technology pilot called ''Myrrha'' that is proposed by Belgium |deadurl=yes |archiveurl=https://web.archive.org/web/20131009042600/http://euronuclear.org/1-information/news/Gen-IV.htm |archivedate=2013-10-09 |df= }}</ref> The central European [[Visegrád Group]] are committed to pursuing the technology.<ref>{{cite web |url=http://www.alphagalileo.org/ViewItem.aspx?ItemId=133111&CultureCode=en |title=The V4G4 Centre of Excellence for performing joint research, development and innovation in the field of Generation-4 (G4) nuclear reactors have been established. 20 July 2013 National Center for Nuclear Research (NCBJ)}}</ref> In 2013 German, British, and French institutes finished a 3-year collaboration study on the follow on industrial scale design, known as ''GoFastR''.<ref>{{cite web|url=http://www.ist-world.org/ProjectDetails.aspx?ProjectId=5cb8f3f283574cc6b2bdbf72533172d8 |title=the European Gas cooled Fast Reactor |deadurl=yes |archiveurl=https://web.archive.org/web/20131213091046/http://www.ist-world.org/ProjectDetails.aspx?ProjectId=5cb8f3f283574cc6b2bdbf72533172d8 |archivedate=2013-12-13 |df= }}</ref> They were funded by the EU's 7th FWP [[framework programme]], with the goal of making a sustainable VHTR.<ref>{{cite web |url=http://www.2020-horizon.com/GOFASTR-European-Gas-Cooled-Fast-Reactor%28GOFASTR%29-s312.html |title=The GOFASTR research program}}</ref>

==== Sodium-cooled fast reactor (SFR) ====
[[File:Sodium-Cooled Fast Reactor Schemata.svg|right|thumb|Pool design Sodium-Cooled Fast Reactor (SFR)]]
{{Main article|Sodium-cooled fast reactor}}
{{see also|Prototype Fast Breeder Reactor|Experimental Breeder Reactor II|S-PRISM|BN-800 reactor|Toshiba 4S|CFR-600}}

In India, the [[Fast Breeder Test Reactor]] reached criticality in October 1985. In September 2002, fuel burn-up in the FBTR for the first time reached the 100,000 megawatt-days per metric ton uranium (MWd/MTU) mark. This is considered an important milestone in breeder reactor technology. Using the experience gained from the operation of the FBTR, the [[Prototype Fast Breeder Reactor]], a 500 MWe Sodium cooled fast reactor is being built at a cost of INR 5,677 crores (~US$900 million) and is expected to be critical by June 2018. The PFBR will be followed by six more Commercial Fast Breeder Reactors (CFBRs) of 600 MWe each.

The SFR<ref name="Roadmap"/> is a project that builds on two closely related existing projects, the liquid metal [[Breeder reactor#Fast breeder reactor|fast breeder reactor]] and the [[integral fast reactor]].

The goals are to increase the efficiency of uranium usage by [[breeder reactor|breeding]] plutonium and eliminating the need for [[transuranic]] isotopes ever to leave the site. The reactor design uses an unmoderated core running on [[fast neutron]]s, designed to allow any transuranic isotope to be consumed (and in some cases used as fuel). In addition to the benefits of removing the long [[half-life]] transuranics from the waste cycle, the SFR fuel expands when the reactor overheats, and the chain reaction automatically slows down. In this manner, it is passively safe.<ref>{{cite web |url=http://www.ne.anl.gov/About/hn/logos-winter02-psr.shtml|title=Passively safe reactors rely on nature to keep them cool|author=David Baurac}}</ref>

The SFR reactor concept is cooled by liquid [[sodium]] and fueled by a metallic alloy of uranium and [[plutonium]] or [[spent nuclear fuel]], the "nuclear waste" of [[light water reactor]]s. The SFR fuel is contained in steel cladding with liquid sodium filling in the space between the clad elements which make up the fuel assembly. One of the design challenges of an SFR is the risks of handling sodium, which reacts explosively if it comes into contact with water. However, the use of liquid metal instead of water as coolant allows the system to work at atmospheric pressure, reducing the risk of leakage.

[[File:Ifr concept.jpg|thumb|375px|The sustainable fuel-cycle proposed in the 1990s [[Integral fast reactor]] concept (color), an animation of the [[pyroprocessing]] technology is also available.<ref>{{cite web |url=https://www.youtube.com/watch?v=cBThTwFhRlA |title=Historical video about the Integral Fast Reactor (IFR) concept. Uploaded by - Nuclear Engineering at Argonne}}</ref>]]
[[File:IFR concept.png|thumb|375px|IFR concept (Black and White with clearer text)]]

The European Sustainable Nuclear Industrial Initiative is funding three Generation IV reactor systems, one of which is a sodium-cooled fast reactor, called ''[[ASTRID (reactor)|ASTRID]]'', Advanced Sodium Technical Reactor for Industrial Demonstration, [[Areva]], [[Commissariat à l'énergie atomique et aux énergies alternatives|CEA]] and [[Électricité de France|EDF]] are leading the design with British collaboration.<ref>{{cite web |url=http://www.power-eng.com/articles/2010/11/areva--cea-secure.html |title=Areva, CEA secure EUR650m funding to develop ASTRID sodium-cooled Generation IV reactor 11/11/2010}}</ref><ref>{{cite web |url=http://www.powermag.com/uk-and-france-sign-landmark-civil-nuclear-cooperation-agreement/ |title=UK and France Sign Landmark Civil Nuclear Cooperation Agreement 02/22/2012 . POWERnews}}</ref> Astrid will be rated about 600 MWe and is proposed to be built in France, near to the [[Phénix]] reactor. A final decision in construction is to be made in 2019<ref name="euronuclear.org"/>

The [[China|PRC]]'s first commercial-scale, 800 MWe, fast neutron reactor, to be situated near [[Sanming]] in [[Fujian province]] will be a SFR. In 2009 an agreement was signed that would entail the Russian [[BN-800 reactor]] design to be sold to the PRC once it is completed, this would be the first time commercial-scale fast neutron reactors have ever been exported.<ref>{{cite web |url=http://www.world-nuclear-news.org/C-Joint_venture_launched_for_Chinese_fast_reactor-3004104.html |title=Joint venture launched for Chinese fast reactor}}</ref> The BN-800 reactor became operational in 2014.

The 400 MWe [[Fast Flux Test Facility]] operated successfully for ten years at the Hanford site in Washington State.

The 20 MWe [[EBR II]] operated successfully for over thirty years at the Idaho National Laboratory, until it was shut down in 1994.

GE Hitachi's [[PRISM (reactor)|PRISM]] reactor is a modernized and commercial implementation of the technology developed for the Integral Fast Reactor(IFR), developed by [[Argonne National Laboratory]] between 1984 and 1994. With the primary purpose of PRISM differing in the focus on burning up [[spent nuclear fuel]] from other reactors, rather than [[breeder reactor|breeding]] new fuel. Presented as an alternative to burying the spent fuel/waste, the design reduces the half lives of the fissionable elements present in spent nuclear fuel while generating electricity largely as a by-product.

==== Lead-cooled fast reactor (LFR) ====
[[File:Lead-Cooled Fast Reactor Schemata.svg|right|thumb|Lead-Cooled Fast Reactor (LFR)]]
{{Main article|Lead-cooled fast reactor}}
{{See also|MYRRHA}}
The '''lead-cooled fast reactor'''<ref name="Roadmap">{{cite journal|year=2002 |title=A Technology Roadmap for Generation IV Nuclear Energy Systems |last=US DOE Nuclear Energy Research Advisory Committee |volume=GIF-002-00 |url=http://nuclear.energy.gov/genIV/documents/gen_iv_roadmap.pdf |deadurl=yes |archiveurl=https://web.archive.org/web/20071129121214/http://nuclear.energy.gov/genIV/documents/gen_iv_roadmap.pdf |archivedate=2007-11-29 |df= }}</ref> features a fast-neutron-spectrum [[lead]] or [[lead]]/[[bismuth]] [[eutectic]] ([[Lead-bismuth eutectic|LBE]]) liquid-metal-cooled reactor with a closed [[Nuclear fuel cycle|fuel cycle]]. Options include a range of plant ratings, including a "battery" of 50 to 150 MW of electricity that features a very long refueling interval, a modular system rated at 300 to 400 MW, and a large monolithic plant option at 1,200 MW (The term ''battery'' refers to the long-life, factory-fabricated core, not to any provision for electrochemical energy conversion). The fuel is metal or nitride-based containing [[Fertile material|fertile uranium]] and [[transuranic]]s. The LFR is cooled by natural [[convection]] with a reactor outlet coolant temperature of 550 °C, possibly ranging up to 800 °C with advanced materials. The higher temperature enables the production of [[Thermochemical cycle|hydrogen by thermochemical processes]].

The European Sustainable Nuclear Industrial Initiative is funding three Generation IV reactor systems, one of which is a lead-cooled fast reactor that is also an [[Subcritical reactor|accelerator-driven sub-critical]] reactor, called ''[[MYRRHA]]'', 100 MW(t), which will be built in [[Belgium]] with construction expected to begin after 2014 and the industrial scale version, known as ''Alfred'', slated to be constructed sometime after 2017. A reduced-power model of Myrrha called ''Guinevere'' was started up at [[Mol, Belgium|Mol]] in March 2009.<ref name="euronuclear.org"/> In 2012 the research team reported that Guinevere was operational.<ref>{{cite news|last1=Hellemans|first1=Alexander|title=Reactor-Accelerator Hybrid Achieves Successful Test Run|url=http://news.sciencemag.org/physics/2012/01/reactor-accelerator-hybrid-achieves-successful-test-run|accessdate=29 December 2014|work=Science Insider|date=12 January 2012}}</ref>

Two other lead-cooled fast reactors under development are the SVBR-100, a modular 100 MWe lead-bismuth cooled fast neutron reactor concept designed by OKB [[Gidropress]] in Russia and the [[BREST (Reactor)|BREST-OD-300]] (Lead-cooled fast reactor) 300 MWe, to be developed after the SVBR-100, and built over 2016-20, it will dispense with the [[Uranium-238|fertile blanket]] around the core and will supersede the sodium cooled [[BN-600 reactor]] design, to purportedly give enhanced proliferation resistance.<ref name="powertecrussia.com"/>

== Advantages and disadvantages ==
Relative to current nuclear power plant technology, the claimed benefits for 4th generation reactors include:
* Nuclear waste that remains radioactive for a few centuries instead of millennia<ref>{{cite web |title=Strategies to Address Global Warming |url=http://www.columbia.edu/~jeh1/mailings/2009/20090713_Strategies.pdf}}</ref>
* 100–300 times more energy yield from the same amount of nuclear fuel<ref>{{cite web |title=4th Generation Nuclear Power |url=http://www.ossfoundation.us/projects/energy/nuclear}}</ref>
* Broader range of fuels, and even unencapsulated raw fuels (non-pebble [[Molten Salt Reactor|MSR]], [[Liquid fluoride thorium reactor|LFTR]]).
* In some reactors, the ability to consume existing nuclear waste in the production of electricity, that is, a Closed [[nuclear fuel cycle]]. This strengthens the argument to deem [[nuclear power as renewable energy]].
* Improved operating safety features, such as (depending on design) avoidance of pressurized operation, automatic passive (unpowered, uncommanded) reactor shutdown, avoidance of water cooling and the associated risks of loss of water (leaks or boiling) and hydrogen generation/explosion and contamination of coolant water.

Nuclear reactors do not emit CO2 during operation, although like all [[low carbon power]] sources, the mining and construction phase can result in CO2 emissions, if energy sources which are not carbon neutral (such as fossil fuels), or CO2 emitting cements are used during the construction process.
A 2012 [[Yale University]] review published in the Journal of Industrial Ecology analyzing {{CO2}} [[life cycle assessment]] (LCA) emissions from [[nuclear power]] determined that:<ref name="Warner + Heath, JoIE">{{cite journal |doi=10.1111/j.1530-9290.2012.00472.x|title=Life Cycle Greenhouse Gas Emissions of Nuclear Electricity Generation|journal=Journal of Industrial Ecology|volume=16|pages=S73–S92|year=2012|last1=Warner|first1=Ethan S|last2=Heath|first2=Garvin A}}</ref>
{{Quote|The collective LCA literature indicates that life cycle [[Greenhouse gas|GHG]] [greenhouse gas] emissions from nuclear power are only a fraction of traditional fossil sources and comparable to renewable technologies.}}
Although the paper primarily dealt with data from [[Generation II reactor]]s, and did not analyze the {{CO2}} emissions by 2050 of the presently under construction [[Generation III reactor]]s, it did summarize the Life Cycle Assessment findings of in development reactor technologies.{{Quote|FBRs ['[[Fast Breeder Reactor]]s'] have been evaluated in the LCA literature. The limited literature that evaluates this potential future technology reports [[median]] life cycle GHG emissions... similar to or lower than LWRs [Gen II [[light water reactor]]s] and purports to consume little or no [[uranium market|uranium ore]].}}

A specific risk of the sodium-cooled fast reactor is related to using metallic sodium as a coolant. In case of a breach, sodium explosively reacts with water. Fixing breaches may also prove dangerous, as the cheapest noble gas [[argon]] is also used to prevent sodium oxidation. Argon, like helium, can displace oxygen in the air and can pose [[hypoxia (environmental)|hypoxia]] concerns, so workers may be exposed to this additional risk. This is a pertinent problem as demonstrated by the events at the [[LMFBR|loop type]] [[Monju Nuclear Power Plant|Prototype Fast Breeder Reactor Monju]] at Tsuruga, Japan.<ref>{{cite news |title=Japan Strains to Fix a Reactor Damaged Before Quake |url=https://www.nytimes.com/2011/06/18/world/asia/18japan.html | work=The New York Times | first=Hiroko |last=Tabuchi |date=17 June 2011}}</ref>
Using lead or molten salts mitigates this problem by making the coolant less reactive and allowing a high freezing temperature and low pressure in case of a leak. Disadvantages of lead compared to sodium are much higher viscosity, much higher density, lower heat capacity, and more radioactive neutron activation products.

In many cases, there is already a large amount of experience built up with numerous proof of concept Gen IV designs. For example, the reactors at [[Fort St. Vrain Generating Station]] and [[HTR-10]] are similar to the proposed Gen IV [[VHTR]] designs, and the [[LMFBR|pool type]] [[EBR-II]], [[Phénix]] and [[BN-600]] reactor are similar to the proposed pool type Gen IV Sodium Cooled Fast reactors being designed.

== Table of designs ==

{| class=wikitable
|+ Summary of designs for generation IV reactors<ref>{{cite web |title=GIF R&D Outlook for Generation IV Nuclear Energy Systems |date=21 August 2009 |url=https://www.gen-4.org/gif/upload/docs/application/pdf/2013-09/gif_rd_outlook_for_generation_iv_nuclear_energy_systems.pdf |accessdate=August 30, 2018}}</ref>
|-
! System
! Neutron Spectrum
! Coolant
! Temperature (°C)
! Fuel Cycle
! Size (MW)
!Example developers
|-
| [[Very-high-temperature reactor|VHTR]]
| Thermal
| Helium
| 900–1000
| Open
| 250–300
|[[Japan Atomic Energy Agency|JAEA]] ([[High-temperature engineering test reactor|HTTR]]), [[Tsinghua University]] ([[HTR-10]]), [[X-energy]]<ref name="energy.gov">{{cite web|title=Energy Department Announces New Investments in Advanced Nuclear Power Reactors…|url=https://www.energy.gov/articles/energy-department-announces-new-investments-advanced-nuclear-power-reactors-help-meet|website=[[United States Department of Energy|US Department of Energy]]|accessdate=16 January 2016}}</ref>
|-
| [[Sodium-cooled fast reactor|SFR]]
| Fast
| Sodium
| 550
| Closed
| 30–150, 300–1500, 1000–2000
|[[TerraPower]] ([[Traveling wave reactor|TWR]]), [[Toshiba]] ([[Toshiba 4S|4S]]), [[GE Hitachi Nuclear Energy]] ([[PRISM (reactor)|PRISM]])
|-
| [[Supercritical water reactor|SCWR]]
| Thermal or fast
| Water
| 510–625
| Open or closed
| 300–700, 1000–1500
|
|-
| [[Gas-cooled fast reactor|GFR]]
| Fast
| Helium
| 850
| Closed
| 1200
|[[Energy Multiplier Module]]
|-
| [[Lead-cooled fast reactor|LFR]]
| Fast
| Lead
| 480–800
| Closed
| 20–180, 300–1200, 600–1000
|
|-
| [[Molten salt reactor|MSR]]
| Fast or thermal
| Fluoride or chloride salts
| 700–800
| Closed
| 250, 1000
|[[Seaborg Technologies]], [[TerraPower]], [[Stable Salt Reactor|Moltex Energy]], [[Flibe Energy]] ([[Liquid fluoride thorium reactor|LFTR]]), [[Transatomic Power]], Thorium Tech Solution ([[Fuji Molten Salt Reactor|FUJI MSR]]), Terrestrial Energy ([[IMSR]]), [[Southern Company Services|Southern Company]]<ref name="energy.gov"/>
|-
| [[Dual fluid reactor|DFR]]
| Fast
| Lead
| 1000
| Closed
| 500–1500
| Institute for Solid-State Nuclear Physics<ref name=ifk>{{cite web |url=https://festkoerper-kernphysik.de/dfr.pdf |title=Dual Fluid Reactor - IFK |date=2013-06-16 |website=festkoerper-kernphysik.de |publisher= Institut für Festkörper-Kernphysik |format=PDF |location=Berlin, Germany |access-date=2017-08-28}}</ref>
|}

== See also ==
{{portal|Energy|Nuclear technology}}
{{colbegin}}
* [[Nuclear reactor]]
* [[Nuclear material]]
* [[Nuclear physics]]
* [[List of reactor types#Reactor types|List of reactor types]]
* [[Generation II reactor]]
* [[Generation III reactor]]
* [[Integral Fast Reactor]]
* [[Liquid fluoride thorium reactor]]
* [[Breeder reactor]]
* [[Small modular reactor]]
* [[List of nuclear reactors]]
{{colend}}

==References==
{{Reflist|30em}}

== External links ==
* [https://inlportal.inl.gov/portal/server.pt?open=514&objID=1361&parentname=CommunityPage&parentid=10&mode=2&in_hi_userid=200&cached=true Article from Idaho National Laboratory detailing some current efforts at developing Gen. IV reactors.]
* [http://www.gen-4.org/ Generation IV International Forum (GIF)]
* [https://web.archive.org/web/20070205115654/http://nuclear.energy.gov/genIV/neGenIV1.html U.S. Department of Energy Office of Nuclear Energy, Science and Technology]
* [https://web.archive.org/web/20060512033030/http://www.engr.utk.edu/nuclear/colloquia/slides/Gen%20IV%20U-Tenn%20Presentation.pdf Gen IV presentation]
* [http://www.ecology.at/ecology/files/pr577_1.pdf Science or Fiction - Is there a Future for Nuclear?] (Nov. 2007) - A publication from the Austrian [[Ecology Institute (Austria)|Ecology Institute]] about 'Generation IV' and Fusion reactors.
* {{cite web |url=http://memagazine.asme.org/Articles/2011/December/Nuclear_Power_After_Fukushima.cfm |title=Nuclear Power After Fukushima |author=Gail H. Marcus |date=December 2011 |website=Mechanical Engineering (the magazine of [[ASME]]) |accessdate=23 January 2012}} "In the wake of a severe plant accident, advanced reactor designs are getting renewed attention."
* [http://www.itheo.org/ International Thorium Energy Organisation - www.IThEO.org]
* [http://www.ithec.org/ International Thorium Energy Committee - iThEC]

{{Nuclear fission reactors}}

[[Category:Nuclear power reactor types]]
[[Category:Idaho National Laboratory]]

Benutzer:Snackroeg/Kernreaktoren der Generation 5

2018-09-29T14:56:57Z

Boundarylayer: "efficient" clarification

{{update|date=October 2017}}
[[File:GenIVRoadmap-en.svg|thumb|480px|Nuclear Energy Systems Deployable no later than 2030 and offering significant advances in sustainability, safety and reliability, and economics]]

'''Generation IV reactors''' ('''Gen IV''') are a set of [[nuclear reactor]] designs currently being researched for commercial applications by the Generation IV International Forum, with [[Technology readiness level]]s varying between the level requiring a demonstration, to economical competitive implementation.<ref name=Locatelli>{{Cite journal|last=Locatelli|first=Giorgio|last2=Mancini|first2=Mauro|last3=Todeschini|first3=Nicola|date=2013-10-01|title=Generation IV nuclear reactors: Current status and future prospects|journal=Energy Policy|volume=61|pages=1503–1520|doi=10.1016/j.enpol.2013.06.101}}</ref> They are motivated by a variety of goals including improved safety, sustainability, efficiency, and cost.

The most developed Gen IV reactor design, the [[sodium fast reactor]], has received the greatest share of funding over the years with a number of demonstration facilities operated, the principle Gen IV aspect of the design, relates in largest part to the development of a sustainable closed [[Nuclear_fuel_cycle#Plutonium_cycle|fuel cycle]] for the reactor. Amongst nuclear engineers the [[molten-salt reactor]], the least developed and funded technology, is considered as potentially having the greatest [[Passive nuclear safety|inherent safety]] of the six models.<ref>{{cite web|url=https://www.scientificamerican.com/article/can-sodium-save-nuclear-power/|title=Can Sodium Save Nuclear Power?|publisher=}}</ref><ref>{{cite journal |last1=Moir |first1=Ralph |last2=Teller |first2=Edward |year=2005 |title=Thorium-Fueled Underground Power Plant Based on Molten Salt Technology |journal=Nuclear Technology |volume=151 |issue=3 |pages=334–340 |url=http://www.new.ans.org/pubs/journals/nt/a_3655 |accessdate=March 22, 2012 }}</ref> While the [[hydrogen economy]], the [[high temperature electrolysis|thermochemical production]] of hydrogen to synthesize [[Carbon-neutral fuel]]s, is deemed as strengthening the economic case for the two most [[Brayton cycle|thermodynamically efficient]] models, the [[Very-high-temperature reactor|high temperature reactor]] designs.<ref name=Locatelli/>

The majority of the 6 designs are generally not expected to be available for commercial construction until 2020–30.<ref name="Generation IV">{{cite web|url=http://www.world-nuclear.org/info/Nuclear-Fuel-Cycle/Power-Reactors/Generation-IV-Nuclear-Reactors/|title=Generation IV Nuclear Reactors: WNA - World Nuclear Association|website=www.world-nuclear.org}}</ref> Presently the majority of reactors in operation around the world are considered [[Generation II reactor|second generation reactor]] systems, as the vast majority of the [[Nuclear reactor#Classification by generation|first generation]] systems were retired some time ago, and there are only a dozen or so [[Generation III reactor]]s in operation as of 2014.
[[Nuclear reactor#Generation V+ reactors|Generation V reactors]] refer to reactors that are purely theoretical and are therefore not yet considered feasible in the short term, resulting in limited [[R&D]] funding.

== History ==
The Generation IV International Forum (GIF) is "a co-operative international endeavour which was set up to carry out the research and development needed to establish the feasibility and performance capabilities of the next generation nuclear energy systems."<ref>{{Cite web|url=https://www.gen-4.org/gif/jcms/c_9260/public|title=GIF Portal - Home - Public|website=www.gen-4.org|access-date=2016-07-25}}</ref> It was founded in 2001. Currently active members of the Generation IV International Forum (GIF) include: [[Australia]], [[Canada]], [[China]], the [[European Atomic Energy Community]] (Euratom), [[France]], [[Japan]], [[Russia]], [[South Africa]], [[South Korea]], [[Switzerland]], and the [[United States]]. The non-active members are [[Argentina]], [[Brazil]], and the [[United Kingdom]].<ref name="gen-4">{{cite web|url=https://www.gen-4.org/gif/jcms/c_9492/members|title=GIF Membership|website=gen-4.org|accessdate=28 October 2014}}</ref> Switzerland joined in 2002, Euratom in 2003, and China and Russia in 2006. The remaining countries (excluding Australia) were founding members.<ref name="gen-4" />

The 36th GIF meeting in [[Brussels]] was held in November 2013.<ref>{{cite web|url=https://www.energy.gov/ne/articles/generation-iv-international-forum-updates-technology-roadmap-and-builds-future|title=generation IV international forum updates technology roadmap and builds future. DOE}}</ref><ref>{{cite web|url=http://events.r20.constantcontact.com/register/event?llr=mscrkjkab&oeidk=a07e7melf609716b2c6 |title=The Generation IV international forum holds their 36th meeting on Monday 18th Nov 2013 in Brussels }}{{dead link|date=January 2017 |bot=InternetArchiveBot |fix-attempted=yes }}</ref> The ''Technology Roadmap Update for Generation IV Nuclear Energy Systems'' was published in January 2014 which details R&D objectives for the next decade.<ref>{{cite web|url=https://www.gen-4.org/gif/upload/docs/application/pdf/2014-03/gif-tru2014.pdf|archive-url=https://web.archive.org/web/20140625102915/https://www.gen-4.org/gif/upload/docs/application/pdf/2014-03/gif-tru2014.pdf|dead-url=yes|archive-date=25 June 2014|title=Wayback Machine|date=25 June 2014|publisher=}}</ref> A breakdown of the reactor designs being researched by each forum member has been made available.<ref>{{cite web|url=https://www.gen-4.org/gif/upload/docs/application/pdf/2014-03/gif_overview_presentation_v9_final3_web.pdf|archive-url=https://web.archive.org/web/20140708023538/https://www.gen-4.org/gif/upload/docs/application/pdf/2014-03/gif_overview_presentation_v9_final3_web.pdf|dead-url=yes|archive-date=8 July 2014|title=Wayback Machine|date=8 July 2014|publisher=}}</ref>

[[Nuclear power in Australia|Australia]] joined the forum in 2016.<ref>{{cite web|url=https://www.gen-4.org/gif/jcms/c_71564/australia-joins-the-generation-iv-international-forum|archiveurl=https://archive.today/20160907131656/https://www.gen-4.org/gif/jcms/c_71564/australia-joins-the-generation-iv-international-forum|deadurl=yes|title=GIF Portal - Australia joins the Generation IV International Forum|date=7 September 2016|archivedate=7 September 2016|publisher=}}</ref>

In January 2018, it was reported that "the first installation of the pressure vessel cover of the world's first Gen IV reactor" had been completed on the [[HTR-PM]].<ref>{{cite web|url=http://www.world-nuclear-news.org/NN-First-HTR-PM-vessel-head-in-place-0401185.html|title=First HTR-PM vessel head in place - World Nuclear News|website=www.world-nuclear-news.org}}</ref>

== Reactor types ==
Many reactor types were considered initially; however, the list was downsized to focus on the most promising technologies and those that could most likely meet the goals of the Gen IV initiative.<ref name="Generation IV"/> Three systems are nominally [[thermal reactor]]s and four are [[fast reactor]]s. The Very High Temperature Reactor (VHTR) is also being researched for potentially providing high quality process heat for [[thermochemical cycle|hydrogen production]]. The fast reactors offer the possibility of burning [[actinides]] to further reduce waste and of being able to "[[breeder reactor|breed more fuel]]" than they consume. These systems offer significant advances in sustainability, safety and reliability, economics, proliferation resistance (depending on perspective) and physical protection.

=== Thermal reactors ===
A [[Thermal-neutron reactor|thermal reactor]] is a [[nuclear reactor]] that uses slow or [[thermal neutrons]]. A [[neutron moderator]] is used to slow the [[neutron]]s emitted by fission to make them more likely to be captured by the fuel.

==== Very-high-temperature reactor (VHTR) ====
[[File:Very High Temperature Reactor.svg|right|thumb|Very-High-Temperature Reactor (VHTR)]]
{{Main article|Very high temperature reactor}}
{{see also|Fort St. Vrain Generating Station|High-temperature engineering test reactor|HTR-10}}
The '''very high temperature reactor''' concept uses a [[graphite]]-moderated core with a once-through [[uranium]] fuel cycle, using helium or molten salt as the [[Very high temperature reactor#Coolant|coolant]]. This reactor design envisions an outlet temperature of 1,000 °C. The reactor core can be either a prismatic-block or a [[pebble bed reactor]] design. The high temperatures enable applications such as process heat or [[hydrogen]] production via the thermochemical [[Sulfur-iodine cycle|iodine-sulfur]] process. It would also be [[Passive nuclear safety|passively safe]].

The planned construction of the first VHTR, the South African PBMR ([[pebble bed modular reactor]]), lost government funding in February, 2010.<ref>[http://www.powergenworldwide.com/index/display/articledisplay/6322207443/articles/power-engineering-international/volume-18/Issue_3/regulars/world-news/INTERNATIONAL.html South Africa to stop funding Pebble Bed nuclear reactor] {{webarchive|url=https://web.archive.org/web/20100909172743/http://www.powergenworldwide.com/index/display/articledisplay/6322207443/articles/power-engineering-international/volume-18/Issue_3/regulars/world-news/INTERNATIONAL.html |date=2010-09-09 }}</ref> A pronounced increase of costs and concerns about possible unexpected technical problems had discouraged potential investors and customers.

The [[People's Republic of China]] began construction of a 200-MW High Temperature Pebble bed reactor in 2012 as a successor to its [[HTR-10]].<ref>{{cite web|url=http://www.nucnet.org/all-the-news/2013/01/07/china-begins-construction-of-first-generation-iv-htr-pm-unit|title=China Begins Construction Of First Generation IV HTR-PM Unit|first=Central Office, NucNet a.s.b.l., Brussels,|last=Belgium|website=www.nucnet.org}}</ref>

Also in 2012, as part of the [[Next Generation Nuclear Plant]] competition, [[Idaho National Laboratory]] approved a design similar to [[Areva]]'s prismatic block [https://web.archive.org/web/20150722041246/http://us.areva.com/EN/home-3225/areva-inc-areva-htgr.html Antares reactor] as the chosen [[HTGR]] to be deployed as a prototype by 2021. It was in competition with [[General Atomics]]' [[Gas turbine modular helium reactor]] and [[Westinghouse Electric Company|Westinghouse]]'s [[Pebble Bed Modular Reactor]].<ref name="World nuclear news">{{cite web|url=http://www.world-nuclear-news.org/NN-Areva_modular_reactor_selected_for_NGNP_development-1502124.html|title=INL approves Antares design}}</ref>

[[X-energy]] was awarded a five-year $53M U.S. Department of Energy Advanced Reactor Concept Cooperative Agreement award to advance elements of their reactor development.<ref>{{cite web|url=https://www.x-energy.com/doe-partnership|title=x-energy - DOE Partnership|website=x-energy}}</ref>
The [[X-energy#Reactor Design|Xe-100]] is a pebble-bed modular reactor and will generate 200-MWt and approximately 76-MWe. The standard Xe-100 "four-pack" plant generates approximately 300-MWe and will fit on as few as 13 acres. All of the components for the Xe-100 will be road-transportable, and will be installed, rather than constructed, at the project site to streamline construction.<ref name="X-energy">{{cite web|url=https://www.x-energy.com/|title=x-energy|website=x-energy}}</ref>

==== Molten-salt reactor (MSR) ====
[[File:Molten Salt Reactor.svg|right|thumb|Molten Salt Reactor (MSR)]]
{{Main article|Molten salt reactor}}
{{see also|Liquid fluoride thorium reactor}}
A '''molten salt reactor'''<ref name="Roadmap"/> is a type of [[nuclear reactor]] where the primary [[coolant]], or even the fuel itself is a molten salt mixture. There have been many designs put forward for this type of reactor and a few prototypes built. The early concepts and many current ones rely on [[nuclear fuel]], perhaps [[uranium tetrafluoride]] (UF4) or [[thorium tetrafluoride]] (ThF4), dissolved in molten [[fluoride]] salt. The fluid would reach [[Nuclear reactor physics#Criticality|criticality]] by flowing into a core where [[graphite]] would serve as the [[neutron moderator|moderator]]. Many current concepts rely on fuel that is dispersed in a graphite matrix with the molten salt providing low pressure, high temperature cooling.

The Gen IV MSR is more accurately termed an [[epithermal neutron|epithermal reactor]] than a thermal reactor due to the average speed of the neutrons that would cause the fission events within its fuel being faster than [[thermal neutron]]s.<ref>{{cite web |url=https://inlportal.inl.gov/portal/server.pt?open=514&objID=1361&parentname=CommunityPage&parentid=10&mode=2&in_hi_userid=200&cached=true |title=Idaho National Laboratory detailing some current efforts at developing Gen. IV reactors}}</ref>

The principle of a MSR can be used for thermal, epithermal and fast reactors. Since 2005 the focus has moved towards a fast spectrum MSR (MSFR).<ref>H. Boussier, S. Delpech, V. Ghetta et Al. : The Molten Salt Reactor (MSR) in Generation IV: Overview and Perspectives, GIF SYMPOSIUM PROCEEDINGS/2012 ANNUAL REPORT, NEA No. 7141, pp95 [https://www.gen-4.org/gif/jcms/c_44720/annual-reports]
</ref>

While most MSR designs being pursued are largely derived from the 1960s [[Molten-Salt Reactor Experiment]] (MSRE), variants of molten salt technology include the conceptual ''[[Dual fluid reactor]]'' which is being designed with lead as a cooling medium but molten salt fuel, commonly as the metal chloride e.g. [[Plutonium(III) chloride]], to aid in greater "nuclear waste" closed-fuel cycle capabilities.
Other notable approaches differing substantially from MSRE include the ''[[Stable Salt Reactor]]'' (SSR) concept promoted by MOLTEX, which encases the molten salt in hundreds of the common solid [[fuel rod]]s that are already well established in the nuclear industry. This latter British design was found to be the most competitive for [[Small modular reactor]] development by a British-based consultancy firm ''Energy Process Development'' in 2015.<ref>{{cite web|url=http://www.daretothink.org/europe-moltex-stable-salt-reactor/|title=Europe: Moltex' Stable Salt Reactor|date=20 April 2015|publisher=}}</ref><ref>{{cite web|url=http://analysis.nuclearenergyinsider.com/moltex-energy-sees-uk-canada-smr-licensing-springboard-asia|title=Moltex Energy sees UK, Canada SMR licensing as springboard to Asia - Nuclear Energy Insider|website=analysis.nuclearenergyinsider.com}}</ref>

Another notable feature of the MSR is the possibility of a [[Thermal-neutron reactor|thermal spectrum]] nuclear [[Nuclear fuel cycle#Fuel cycles|waste-burner]]. Conventionally only fast spectrum reactors have been considered viable for [[Nuclear fuel cycle#Minor actinides recycling|utilization or reduction]] of the [[Spent nuclear fuel|spent nuclear stockpiles]]. The conceptual viability of a thermal waste-burner was first shown in a whitepaper by [[Seaborg Technologies]] spring 2015.<ref name="Seaborg Whitepaper 2015">{{cite web|url=https://seaborg.dk/s/Seaborg-whitepaper-2015.pdf|title=Thermal MSR waste burner benchmark}}</ref> Thermal waste-burning was achieved by replacing a fraction of the [[uranium]] in the spent nuclear fuel with [[thorium]]. The net production rate of [[transuranium element]] (e.g. [[plutonium]] and [[americium]]) is reduced below the consumption rate, thus reducing the magnitude of the [[Radioactive waste|nuclear storage problem]], without the [[nuclear proliferation]] concerns and other [[Fast-neutron reactor#Disadvantages|technical issues]] associated with a [[Fast-neutron reactor|fast reactor]].

==== Supercritical-water-cooled reactor (SCWR) ====
[[File:Supercritical-Water-Cooled Reactor.svg|right|thumb|Supercritical-Water-Cooled Reactor (SCWR)]]
{{Main article|Supercritical water reactor}}
The '''supercritical water reactor''' (SCWR)<ref name="Roadmap"/> is a [[reduced moderation water reactor]] concept that, due to the average speed of the neutrons that would cause the fission events within the fuel being faster than [[thermal neutron]]s, it is more accurately termed an [[epithermal neutron|epithermal reactor]] than a thermal reactor. It uses [[supercritical fluid|supercritical water]] as the working fluid. SCWRs are basically [[light water reactor]]s (LWR) operating at higher pressure and temperatures with a direct, once-through heat exchange cycle. As most commonly envisioned, it would operate on a direct cycle, much like a boiling water reactor ([[BWR]]), but since it uses supercritical water (not to be confused with [[Critical mass (nuclear)|critical mass]]) as the working fluid, it would have only one water phase present, which makes the supercritical heat exchange method more similar to a pressurized water reactor ([[Pressurized water reactor|PWR]]). It could operate at much higher temperatures than both current PWRs and BWRs.

Supercritical water-cooled reactors (SCWRs) are promising advanced nuclear systems because of their high [[thermal efficiency]] (i.e., about 45% vs. about 33% efficiency for current LWRs) and considerable plant simplification.

The main mission of the SCWR is generation of low-cost [[electricity]]. It is built upon two proven technologies, LWRs, which are the most commonly deployed power generating reactors in the world, and superheated [[fossil fuel]] fired [[boiler]]s, a large number of which are also in use around the world. The SCWR concept is being investigated by 32 organizations in 13 countries.{{citation needed|date=October 2012}}

Because SCWRs are water reactors they share the steam explosion and radioactive steam release hazards of BWRs and LWRs as well as the need for extremely expensive heavy duty pressure vessels, pipes, valves, and pumps. These shared problems are inherently more severe for SCWRs due to operation at higher temperatures.

A SCWR Design under development is the [[VVER]]-1700/393 (VVER-SCWR or VVER-SKD) — a Russian Supercritical-water-cooled reactor with double-inlet-core and a [[breeder reactor|breeding ratio]] of 0.95.<ref name="powertecrussia.com">{{cite web |url=http://www.powertecrussia.com/blog/tag/nuclear-power/ |title=Technology Developments & Plant Efficiency for the Russian Nuclear Power Generation Market Wednesday |date=March 24, 2010}}</ref>

=== Fast reactors ===
A [[Fast-neutron reactor|fast reactor]] directly uses the fast neutrons emitted by fission, without moderation. Unlike thermal neutron reactors, fast neutron reactors can be configured to "'''burn'''", or fission, all [[actinides]], and given enough time, therefore drastically reduce the actinides fraction in [[spent nuclear fuel]] produced by the present world fleet of thermal neutron [[light water reactor]]s, thus closing the [[nuclear fuel cycle]]. Alternatively, if configured differently, they can also [[breeder reactor|'''breed''']] more actinide fuel than they consume.

==== Gas-cooled fast reactor (GFR) ====
[[File:Gas-Cooled Fast Reactor Schemata.svg|right|thumb|Gas-Cooled Fast Reactor (GFR)]]
{{Main article|Gas-cooled fast reactor}}
The '''gas-cooled fast reactor''' (GFR)<ref name="Roadmap"/> system features a fast-neutron spectrum and closed fuel cycle for efficient conversion of [[Fertile material|fertile uranium]] and management of actinides. The reactor is [[helium]]-cooled and with an outlet temperature of 850 °C it is an evolution of the [[very-high-temperature reactor]] (VHTR) to a more sustainable fuel cycle. It will use a direct [[Brayton cycle]] [[Closed-cycle gas turbine|gas turbine]] for high thermal efficiency. Several fuel forms are being considered for their potential to operate at very high temperatures and to ensure an excellent retention of [[Nuclear fission|fission]] products: composite [[ceramic]] fuel, advanced fuel particles, or ceramic clad elements of actinide compounds. Core configurations are being considered based on pin- or plate-based fuel assemblies or prismatic blocks.

The European Sustainable Nuclear Industrial Initiative is funding three Generation IV reactor systems, one of which is a gas-cooled fast reactor, called ''Allegro'', 100 MW(t), which will be built in a central or eastern European country with construction expected to begin in 2018.<ref name="euronuclear.org">{{cite web|url=https://www.euronuclear.org/1-information/news/Gen-IV.htm |title=The European Sustainable Nuclear Industrial Initiative (ESNII) will support three Generation IV reactor systems: a sodium-cooled fast reactor, or SFR, called ''Astrid'' that is proposed by France; a gas-cooled fast reactor, GFR, called ''Allegro'' supported by central and eastern Europe; and a lead-cooled fast reactor, LFR, technology pilot called ''Myrrha'' that is proposed by Belgium |deadurl=yes |archiveurl=https://web.archive.org/web/20131009042600/http://euronuclear.org/1-information/news/Gen-IV.htm |archivedate=2013-10-09 |df= }}</ref> The central European [[Visegrád Group]] are committed to pursuing the technology.<ref>{{cite web |url=http://www.alphagalileo.org/ViewItem.aspx?ItemId=133111&CultureCode=en |title=The V4G4 Centre of Excellence for performing joint research, development and innovation in the field of Generation-4 (G4) nuclear reactors have been established. 20 July 2013 National Center for Nuclear Research (NCBJ)}}</ref> In 2013 German, British, and French institutes finished a 3-year collaboration study on the follow on industrial scale design, known as ''GoFastR''.<ref>{{cite web|url=http://www.ist-world.org/ProjectDetails.aspx?ProjectId=5cb8f3f283574cc6b2bdbf72533172d8 |title=the European Gas cooled Fast Reactor |deadurl=yes |archiveurl=https://web.archive.org/web/20131213091046/http://www.ist-world.org/ProjectDetails.aspx?ProjectId=5cb8f3f283574cc6b2bdbf72533172d8 |archivedate=2013-12-13 |df= }}</ref> They were funded by the EU's 7th FWP [[framework programme]], with the goal of making a sustainable VHTR.<ref>{{cite web |url=http://www.2020-horizon.com/GOFASTR-European-Gas-Cooled-Fast-Reactor%28GOFASTR%29-s312.html |title=The GOFASTR research program}}</ref>

==== Sodium-cooled fast reactor (SFR) ====
[[File:Sodium-Cooled Fast Reactor Schemata.svg|right|thumb|Pool design Sodium-Cooled Fast Reactor (SFR)]]
{{Main article|Sodium-cooled fast reactor}}
{{see also|Prototype Fast Breeder Reactor|Experimental Breeder Reactor II|S-PRISM|BN-800 reactor|Toshiba 4S|CFR-600}}

In India, the [[Fast Breeder Test Reactor]] reached criticality in October 1985. In September 2002, fuel burn-up in the FBTR for the first time reached the 100,000 megawatt-days per metric ton uranium (MWd/MTU) mark. This is considered an important milestone in breeder reactor technology. Using the experience gained from the operation of the FBTR, the [[Prototype Fast Breeder Reactor]], a 500 MWe Sodium cooled fast reactor is being built at a cost of INR 5,677 crores (~US$900 million) and is expected to be critical by June 2018. The PFBR will be followed by six more Commercial Fast Breeder Reactors (CFBRs) of 600 MWe each.

The SFR<ref name="Roadmap"/> is a project that builds on two closely related existing projects, the liquid metal [[Breeder reactor#Fast breeder reactor|fast breeder reactor]] and the [[integral fast reactor]].

The goals are to increase the efficiency of uranium usage by [[breeder reactor|breeding]] plutonium and eliminating the need for [[transuranic]] isotopes ever to leave the site. The reactor design uses an unmoderated core running on [[fast neutron]]s, designed to allow any transuranic isotope to be consumed (and in some cases used as fuel). In addition to the benefits of removing the long [[half-life]] transuranics from the waste cycle, the SFR fuel expands when the reactor overheats, and the chain reaction automatically slows down. In this manner, it is passively safe.<ref>{{cite web |url=http://www.ne.anl.gov/About/hn/logos-winter02-psr.shtml|title=Passively safe reactors rely on nature to keep them cool|author=David Baurac}}</ref>

The SFR reactor concept is cooled by liquid [[sodium]] and fueled by a metallic alloy of uranium and [[plutonium]] or [[spent nuclear fuel]], the "nuclear waste" of [[light water reactor]]s. The SFR fuel is contained in steel cladding with liquid sodium filling in the space between the clad elements which make up the fuel assembly. One of the design challenges of an SFR is the risks of handling sodium, which reacts explosively if it comes into contact with water. However, the use of liquid metal instead of water as coolant allows the system to work at atmospheric pressure, reducing the risk of leakage.

[[File:Ifr concept.jpg|thumb|375px|The sustainable fuel-cycle proposed in the 1990s [[Integral fast reactor]] concept (color), an animation of the [[pyroprocessing]] technology is also available.<ref>{{cite web |url=https://www.youtube.com/watch?v=cBThTwFhRlA |title=Historical video about the Integral Fast Reactor (IFR) concept. Uploaded by - Nuclear Engineering at Argonne}}</ref>]]
[[File:IFR concept.png|thumb|375px|IFR concept (Black and White with clearer text)]]

The European Sustainable Nuclear Industrial Initiative is funding three Generation IV reactor systems, one of which is a sodium-cooled fast reactor, called ''[[ASTRID (reactor)|ASTRID]]'', Advanced Sodium Technical Reactor for Industrial Demonstration, [[Areva]], [[Commissariat à l'énergie atomique et aux énergies alternatives|CEA]] and [[Électricité de France|EDF]] are leading the design with British collaboration.<ref>{{cite web |url=http://www.power-eng.com/articles/2010/11/areva--cea-secure.html |title=Areva, CEA secure EUR650m funding to develop ASTRID sodium-cooled Generation IV reactor 11/11/2010}}</ref><ref>{{cite web |url=http://www.powermag.com/uk-and-france-sign-landmark-civil-nuclear-cooperation-agreement/ |title=UK and France Sign Landmark Civil Nuclear Cooperation Agreement 02/22/2012 . POWERnews}}</ref> Astrid will be rated about 600 MWe and is proposed to be built in France, near to the [[Phénix]] reactor. A final decision in construction is to be made in 2019<ref name="euronuclear.org"/>

The [[China|PRC]]'s first commercial-scale, 800 MWe, fast neutron reactor, to be situated near [[Sanming]] in [[Fujian province]] will be a SFR. In 2009 an agreement was signed that would entail the Russian [[BN-800 reactor]] design to be sold to the PRC once it is completed, this would be the first time commercial-scale fast neutron reactors have ever been exported.<ref>{{cite web |url=http://www.world-nuclear-news.org/C-Joint_venture_launched_for_Chinese_fast_reactor-3004104.html |title=Joint venture launched for Chinese fast reactor}}</ref> The BN-800 reactor became operational in 2014.

The 400 MWe [[Fast Flux Test Facility]] operated successfully for ten years at the Hanford site in Washington State.

The 20 MWe [[EBR II]] operated successfully for over thirty years at the Idaho National Laboratory, until it was shut down in 1994.

GE Hitachi's [[PRISM (reactor)|PRISM]] reactor is a modernized and commercial implementation of the technology developed for the Integral Fast Reactor(IFR), developed by [[Argonne National Laboratory]] between 1984 and 1994. With the primary purpose of PRISM differing in the focus on burning up [[spent nuclear fuel]] from other reactors, rather than [[breeder reactor|breeding]] new fuel. Presented as an alternative to burying the spent fuel/waste, the design reduces the half lives of the fissionable elements present in spent nuclear fuel while generating electricity largely as a by-product.

==== Lead-cooled fast reactor (LFR) ====
[[File:Lead-Cooled Fast Reactor Schemata.svg|right|thumb|Lead-Cooled Fast Reactor (LFR)]]
{{Main article|Lead-cooled fast reactor}}
{{See also|MYRRHA}}
The '''lead-cooled fast reactor'''<ref name="Roadmap">{{cite journal|year=2002 |title=A Technology Roadmap for Generation IV Nuclear Energy Systems |last=US DOE Nuclear Energy Research Advisory Committee |volume=GIF-002-00 |url=http://nuclear.energy.gov/genIV/documents/gen_iv_roadmap.pdf |deadurl=yes |archiveurl=https://web.archive.org/web/20071129121214/http://nuclear.energy.gov/genIV/documents/gen_iv_roadmap.pdf |archivedate=2007-11-29 |df= }}</ref> features a fast-neutron-spectrum [[lead]] or [[lead]]/[[bismuth]] [[eutectic]] ([[Lead-bismuth eutectic|LBE]]) liquid-metal-cooled reactor with a closed [[Nuclear fuel cycle|fuel cycle]]. Options include a range of plant ratings, including a "battery" of 50 to 150 MW of electricity that features a very long refueling interval, a modular system rated at 300 to 400 MW, and a large monolithic plant option at 1,200 MW (The term ''battery'' refers to the long-life, factory-fabricated core, not to any provision for electrochemical energy conversion). The fuel is metal or nitride-based containing [[Fertile material|fertile uranium]] and [[transuranic]]s. The LFR is cooled by natural [[convection]] with a reactor outlet coolant temperature of 550 °C, possibly ranging up to 800 °C with advanced materials. The higher temperature enables the production of [[Thermochemical cycle|hydrogen by thermochemical processes]].

The European Sustainable Nuclear Industrial Initiative is funding three Generation IV reactor systems, one of which is a lead-cooled fast reactor that is also an [[Subcritical reactor|accelerator-driven sub-critical]] reactor, called ''[[MYRRHA]]'', 100 MW(t), which will be built in [[Belgium]] with construction expected to begin after 2014 and the industrial scale version, known as ''Alfred'', slated to be constructed sometime after 2017. A reduced-power model of Myrrha called ''Guinevere'' was started up at [[Mol, Belgium|Mol]] in March 2009.<ref name="euronuclear.org"/> In 2012 the research team reported that Guinevere was operational.<ref>{{cite news|last1=Hellemans|first1=Alexander|title=Reactor-Accelerator Hybrid Achieves Successful Test Run|url=http://news.sciencemag.org/physics/2012/01/reactor-accelerator-hybrid-achieves-successful-test-run|accessdate=29 December 2014|work=Science Insider|date=12 January 2012}}</ref>

Two other lead-cooled fast reactors under development are the SVBR-100, a modular 100 MWe lead-bismuth cooled fast neutron reactor concept designed by OKB [[Gidropress]] in Russia and the [[BREST (Reactor)|BREST-OD-300]] (Lead-cooled fast reactor) 300 MWe, to be developed after the SVBR-100, and built over 2016-20, it will dispense with the [[Uranium-238|fertile blanket]] around the core and will supersede the sodium cooled [[BN-600 reactor]] design, to purportedly give enhanced proliferation resistance.<ref name="powertecrussia.com"/>

== Advantages and disadvantages ==
Relative to current nuclear power plant technology, the claimed benefits for 4th generation reactors include:
* Nuclear waste that remains radioactive for a few centuries instead of millennia<ref>{{cite web |title=Strategies to Address Global Warming |url=http://www.columbia.edu/~jeh1/mailings/2009/20090713_Strategies.pdf}}</ref>
* 100–300 times more energy yield from the same amount of nuclear fuel<ref>{{cite web |title=4th Generation Nuclear Power |url=http://www.ossfoundation.us/projects/energy/nuclear}}</ref>
* Broader range of fuels, and even unencapsulated raw fuels (non-pebble [[Molten Salt Reactor|MSR]], [[Liquid fluoride thorium reactor|LFTR]]).
* In some reactors, the ability to consume existing nuclear waste in the production of electricity, that is, a Closed [[nuclear fuel cycle]]. This strengthens the argument to deem [[nuclear power as renewable energy]].
* Improved operating safety features, such as (depending on design) avoidance of pressurized operation, automatic passive (unpowered, uncommanded) reactor shutdown, avoidance of water cooling and the associated risks of loss of water (leaks or boiling) and hydrogen generation/explosion and contamination of coolant water.

Nuclear reactors do not emit CO2 during operation, although like all [[low carbon power]] sources, the mining and construction phase can result in CO2 emissions, if energy sources which are not carbon neutral (such as fossil fuels), or CO2 emitting cements are used during the construction process.
A 2012 [[Yale University]] review published in the Journal of Industrial Ecology analyzing {{CO2}} [[life cycle assessment]] (LCA) emissions from [[nuclear power]] determined that:<ref name="Warner + Heath, JoIE">{{cite journal |doi=10.1111/j.1530-9290.2012.00472.x|title=Life Cycle Greenhouse Gas Emissions of Nuclear Electricity Generation|journal=Journal of Industrial Ecology|volume=16|pages=S73–S92|year=2012|last1=Warner|first1=Ethan S|last2=Heath|first2=Garvin A}}</ref>
{{Quote|The collective LCA literature indicates that life cycle [[Greenhouse gas|GHG]] [greenhouse gas] emissions from nuclear power are only a fraction of traditional fossil sources and comparable to renewable technologies.}}
Although the paper primarily dealt with data from [[Generation II reactor]]s, and did not analyze the {{CO2}} emissions by 2050 of the presently under construction [[Generation III reactor]]s, it did summarize the Life Cycle Assessment findings of in development reactor technologies.{{Quote|FBRs ['[[Fast Breeder Reactor]]s'] have been evaluated in the LCA literature. The limited literature that evaluates this potential future technology reports [[median]] life cycle GHG emissions... similar to or lower than LWRs [Gen II [[light water reactor]]s] and purports to consume little or no [[uranium market|uranium ore]].}}

A specific risk of the sodium-cooled fast reactor is related to using metallic sodium as a coolant. In case of a breach, sodium explosively reacts with water. Fixing breaches may also prove dangerous, as the cheapest noble gas [[argon]] is also used to prevent sodium oxidation. Argon, like helium, can displace oxygen in the air and can pose [[hypoxia (environmental)|hypoxia]] concerns, so workers may be exposed to this additional risk. This is a pertinent problem as demonstrated by the events at the [[LMFBR|loop type]] [[Monju Nuclear Power Plant|Prototype Fast Breeder Reactor Monju]] at Tsuruga, Japan.<ref>{{cite news |title=Japan Strains to Fix a Reactor Damaged Before Quake |url=https://www.nytimes.com/2011/06/18/world/asia/18japan.html | work=The New York Times | first=Hiroko |last=Tabuchi |date=17 June 2011}}</ref>
Using lead or molten salts mitigates this problem by making the coolant less reactive and allowing a high freezing temperature and low pressure in case of a leak. Disadvantages of lead compared to sodium are much higher viscosity, much higher density, lower heat capacity, and more radioactive neutron activation products.

In many cases, there is already a large amount of experience built up with numerous proof of concept Gen IV designs. For example, the reactors at [[Fort St. Vrain Generating Station]] and [[HTR-10]] are similar to the proposed Gen IV [[VHTR]] designs, and the [[LMFBR|pool type]] [[EBR-II]], [[Phénix]] and [[BN-600]] reactor are similar to the proposed pool type Gen IV Sodium Cooled Fast reactors being designed.

== Table of designs ==

{| class=wikitable
|+ Summary of designs for generation IV reactors<ref>{{cite web |title=GIF R&D Outlook for Generation IV Nuclear Energy Systems |date=21 August 2009 |url=https://www.gen-4.org/gif/upload/docs/application/pdf/2013-09/gif_rd_outlook_for_generation_iv_nuclear_energy_systems.pdf |accessdate=August 30, 2018}}</ref>
|-
! System
! Neutron Spectrum
! Coolant
! Temperature (°C)
! Fuel Cycle
! Size (MW)
!Example developers
|-
| [[Very-high-temperature reactor|VHTR]]
| Thermal
| Helium
| 900–1000
| Open
| 250–300
|[[Japan Atomic Energy Agency|JAEA]] ([[High-temperature engineering test reactor|HTTR]]), [[Tsinghua University]] ([[HTR-10]]), [[X-energy]]<ref name="energy.gov">{{cite web|title=Energy Department Announces New Investments in Advanced Nuclear Power Reactors…|url=https://www.energy.gov/articles/energy-department-announces-new-investments-advanced-nuclear-power-reactors-help-meet|website=[[United States Department of Energy|US Department of Energy]]|accessdate=16 January 2016}}</ref>
|-
| [[Sodium-cooled fast reactor|SFR]]
| Fast
| Sodium
| 550
| Closed
| 30–150, 300–1500, 1000–2000
|[[TerraPower]] ([[Traveling wave reactor|TWR]]), [[Toshiba]] ([[Toshiba 4S|4S]]), [[GE Hitachi Nuclear Energy]] ([[PRISM (reactor)|PRISM]])
|-
| [[Supercritical water reactor|SCWR]]
| Thermal or fast
| Water
| 510–625
| Open or closed
| 300–700, 1000–1500
|
|-
| [[Gas-cooled fast reactor|GFR]]
| Fast
| Helium
| 850
| Closed
| 1200
|[[Energy Multiplier Module]]
|-
| [[Lead-cooled fast reactor|LFR]]
| Fast
| Lead
| 480–800
| Closed
| 20–180, 300–1200, 600–1000
|
|-
| [[Molten salt reactor|MSR]]
| Fast or thermal
| Fluoride or chloride salts
| 700–800
| Closed
| 250, 1000
|[[Seaborg Technologies]], [[TerraPower]], [[Stable Salt Reactor|Moltex Energy]], [[Flibe Energy]] ([[Liquid fluoride thorium reactor|LFTR]]), [[Transatomic Power]], Thorium Tech Solution ([[Fuji Molten Salt Reactor|FUJI MSR]]), Terrestrial Energy ([[IMSR]]), [[Southern Company Services|Southern Company]]<ref name="energy.gov"/>
|-
| [[Dual fluid reactor|DFR]]
| Fast
| Lead
| 1000
| Closed
| 500–1500
| Institute for Solid-State Nuclear Physics<ref name=ifk>{{cite web |url=https://festkoerper-kernphysik.de/dfr.pdf |title=Dual Fluid Reactor - IFK |date=2013-06-16 |website=festkoerper-kernphysik.de |publisher= Institut für Festkörper-Kernphysik |format=PDF |location=Berlin, Germany |access-date=2017-08-28}}</ref>
|}

== See also ==
{{portal|Energy|Nuclear technology}}
{{colbegin}}
* [[Nuclear reactor]]
* [[Nuclear material]]
* [[Nuclear physics]]
* [[List of reactor types#Reactor types|List of reactor types]]
* [[Generation II reactor]]
* [[Generation III reactor]]
* [[Integral Fast Reactor]]
* [[Liquid fluoride thorium reactor]]
* [[Breeder reactor]]
* [[Small modular reactor]]
* [[List of nuclear reactors]]
{{colend}}

==References==
{{Reflist|30em}}

== External links ==
* [https://inlportal.inl.gov/portal/server.pt?open=514&objID=1361&parentname=CommunityPage&parentid=10&mode=2&in_hi_userid=200&cached=true Article from Idaho National Laboratory detailing some current efforts at developing Gen. IV reactors.]
* [http://www.gen-4.org/ Generation IV International Forum (GIF)]
* [https://web.archive.org/web/20070205115654/http://nuclear.energy.gov/genIV/neGenIV1.html U.S. Department of Energy Office of Nuclear Energy, Science and Technology]
* [https://web.archive.org/web/20060512033030/http://www.engr.utk.edu/nuclear/colloquia/slides/Gen%20IV%20U-Tenn%20Presentation.pdf Gen IV presentation]
* [http://www.ecology.at/ecology/files/pr577_1.pdf Science or Fiction - Is there a Future for Nuclear?] (Nov. 2007) - A publication from the Austrian [[Ecology Institute (Austria)|Ecology Institute]] about 'Generation IV' and Fusion reactors.
* {{cite web |url=http://memagazine.asme.org/Articles/2011/December/Nuclear_Power_After_Fukushima.cfm |title=Nuclear Power After Fukushima |author=Gail H. Marcus |date=December 2011 |website=Mechanical Engineering (the magazine of [[ASME]]) |accessdate=23 January 2012}} "In the wake of a severe plant accident, advanced reactor designs are getting renewed attention."
* [http://www.itheo.org/ International Thorium Energy Organisation - www.IThEO.org]
* [http://www.ithec.org/ International Thorium Energy Committee - iThEC]

{{Nuclear fission reactors}}

[[Category:Nuclear power reactor types]]
[[Category:Idaho National Laboratory]]

Benutzer:Snackroeg/Kernreaktoren der Generation 5

2018-08-01T04:39:19Z

Boundarylayer:

{{update|date=October 2017}}
[[File:GenIVRoadmap-en.svg|thumb|480px|Nuclear Energy Systems Deployable no later than 2030 and offering significant advances in sustainability, safety and reliability, and economics]]

'''Generation IV reactors''' ('''Gen IV''') are a set of [[nuclear reactor]] designs currently being researched for commercial applications by the Generation IV International Forum, with [[Technology readiness level]]s varying between the level requiring a demonstration, to economical competitive implementation.<ref>{{Cite journal|last=Locatelli|first=Giorgio|last2=Mancini|first2=Mauro|last3=Todeschini|first3=Nicola|date=2013-10-01|title=Generation IV nuclear reactors: Current status and future prospects|url=http://www.sciencedirect.com/science/article/pii/S0301421513006083|journal=Energy Policy|volume=61|pages=1503–1520|doi=10.1016/j.enpol.2013.06.101}}</ref> They are motivated by a variety of goals including improved safety, sustainability, efficiency, and cost.

The most developed Gen IV reactor design, the [[sodium fast reactor]], has received the greatest share of funding over the years, with the principle Gen IV aspect of the design, relating in largest part to the development of a sustainable closed [[Nuclear_fuel_cycle#Plutonium_cycle|fuel cycle]] for the reactor. Amongst nuclear engineers the [[molten-salt reactor]], the least developed and funded technology, is considered as potentially having the greatest [[Passive nuclear safety|inherent safety]] of the six models.<ref>[https://www.scientificamerican.com/article/can-sodium-save-nuclear-power/ Can Sodium Save Nuclear Power? Scientific American]</ref><ref>{{cite journal |last1=Moir |first1=Ralph |last2=Teller |first2=Edward |year=2005 |title=Thorium-Fueled Underground Power Plant Based on Molten Salt Technology |journal=Nuclear Technology |volume=151 |issue=3 |pages=334–340 |publisher=[[American Nuclear Society]] |url=http://www.new.ans.org/pubs/journals/nt/a_3655 |accessdate=March 22, 2012 }}</ref> While the [[hydrogen economy]], the [[high temperature electrolysis|thermochemical production]] of hydrogen to synthesize [[Carbon-neutral fuel]]s, is deemed as strengthening the economic case for the two most efficient models, the [[Very-high-temperature reactor|high temperature reactor]] designs.<ref>[https://www.sciencedirect.com/science/article/pii/S0301421513006083 Generation IV nuclear reactors: Current status and future prospects doi.org/10.1016/j.enpol.2013.06.101]</ref>

The majority of the 6 designs are generally not expected to be available for commercial construction until 2020–30.<ref name="Generation IV">[http://www.world-nuclear.org/info/Nuclear-Fuel-Cycle/Power-Reactors/Generation-IV-Nuclear-Reactors/]</ref> Presently the majority of reactors in operation around the world are considered [[Generation II reactor|second generation reactor]] systems, as the vast majority of the [[Nuclear reactor#Classification by generation|first generation]] systems were retired some time ago, and there are only a dozen or so [[Generation III reactor]]s in operation as of 2014.
[[Nuclear reactor#Generation V+ reactors|Generation V reactors]] refer to reactors that are purely theoretical and are therefore not yet considered feasible in the short term, resulting in limited [[R&D]] funding.

== History ==
The Generation IV International Forum (GIF) is "a co-operative international endeavour which was set up to carry out the research and development needed to establish the feasibility and performance capabilities of the next generation nuclear energy systems."<ref>{{Cite web|url=https://www.gen-4.org/gif/jcms/c_9260/public|title=GIF Portal - Home - Public|website=www.gen-4.org|access-date=2016-07-25}}</ref> It was founded in 2001. Currently active members of the Generation IV International Forum (GIF) include: [[Australia]], [[Canada]], [[China]], the [[European Atomic Energy Community]] (Euratom), [[France]], [[Japan]], [[Russia]], [[South Africa]], [[South Korea]], [[Switzerland]], and the [[United States]]. The non-active members are [[Argentina]], [[Brazil]], and the [[United Kingdom]].<ref name="gen-4">{{cite web|url=https://www.gen-4.org/gif/jcms/c_9492/members|title=GIF Membership|website=gen-4.org|accessdate=28 October 2014}}</ref> Switzerland joined in 2002, Euratom in 2003, and China and Russia in 2006. The remaining countries (excluding Australia) were founding members.<ref name="gen-4" />

The 36th GIF meeting in [[Brussels]] was held in November 2013.<ref>{{cite web|url=https://www.energy.gov/ne/articles/generation-iv-international-forum-updates-technology-roadmap-and-builds-future|title=generation IV international forum updates technology roadmap and builds future. DOE}}</ref><ref>{{cite web|url=http://events.r20.constantcontact.com/register/event?llr=mscrkjkab&oeidk=a07e7melf609716b2c6 |title=The Generation IV international forum holds their 36th meeting on Monday 18th Nov 2013 in Brussels. }}{{dead link|date=January 2017 |bot=InternetArchiveBot |fix-attempted=yes }}</ref> The ''Technology Roadmap Update for Generation IV Nuclear Energy Systems'' was published in January 2014 which details R&D objectives for the next decade.<ref>[https://web.archive.org/web/20140625102915/https://www.gen-4.org/gif/upload/docs/application/pdf/2014-03/gif-tru2014.pdf Technology Roadmap Update for Generation IV Nuclear Energy Systems]</ref> A breakdown of the reactor designs being researched by each forum member has been made available.<ref>[https://web.archive.org/web/20140708023538/https://www.gen-4.org/gif/upload/docs/application/pdf/2014-03/gif_overview_presentation_v9_final3_web.pdf Generation IV International Forum, overview, John E. Kelly, page 15]</ref>

[[Nuclear power in Australia|Australia]] joined the forum in 2016.<ref>https://archive.is/20160907131656/https://www.gen-4.org/gif/jcms/c_71564/australia-joins-the-generation-iv-international-forum</ref>

In January 2018, it was reported that "the first installation of the pressure vessel cover of the world's first Gen IV reactor" had been completed on the [[HTR-PM]].<ref>http://www.world-nuclear-news.org/NN-First-HTR-PM-vessel-head-in-place-0401185.html</ref>

== Reactor types ==
Many reactor types were considered initially; however, the list was downsized to focus on the most promising technologies and those that could most likely meet the goals of the Gen IV initiative.<ref name="Generation IV"/> Three systems are nominally [[thermal reactor]]s and four are [[fast reactor]]s. The Very High Temperature Reactor (VHTR) is also being researched for potentially providing high quality process heat for [[thermochemical cycle|hydrogen production]]. The fast reactors offer the possibility of burning [[actinides]] to further reduce waste and of being able to "[[breeder reactor|breed more fuel]]" than they consume. These systems offer significant advances in sustainability, safety and reliability, economics, proliferation resistance (depending on perspective) and physical protection.

=== Thermal reactors ===
A [[Thermal-neutron reactor|thermal reactor]] is a [[nuclear reactor]] that uses slow or [[thermal neutrons]]. A [[neutron moderator]] is used to slow the [[neutron]]s emitted by fission to make them more likely to be captured by the fuel.

==== Very-high-temperature reactor (VHTR) ====
[[File:Very High Temperature Reactor.svg|right|thumb|Very-High-Temperature Reactor (VHTR)]]
{{Main article|Very high temperature reactor}}
{{see also|Fort St. Vrain Generating Station|High-temperature engineering test reactor|HTR-10}}
The '''very high temperature reactor''' concept uses a [[graphite]]-moderated core with a once-through [[uranium]] fuel cycle, using helium or molten salt as the [[Very high temperature reactor#Coolant|coolant]]. This reactor design envisions an outlet temperature of 1,000 °C. The reactor core can be either a prismatic-block or a [[pebble bed reactor]] design. The high temperatures enable applications such as process heat or [[hydrogen]] production via the thermochemical [[Sulfur-iodine cycle|iodine-sulfur]] process. It would also be [[Passive nuclear safety|passively safe]].

The planned construction of the first VHTR, the South African PBMR ([[pebble bed modular reactor]]), lost government funding in February, 2010.<ref>[http://www.powergenworldwide.com/index/display/articledisplay/6322207443/articles/power-engineering-international/volume-18/Issue_3/regulars/world-news/INTERNATIONAL.html South Africa to stop funding Pebble Bed nuclear reactor] {{webarchive|url=https://web.archive.org/web/20100909172743/http://www.powergenworldwide.com/index/display/articledisplay/6322207443/articles/power-engineering-international/volume-18/Issue_3/regulars/world-news/INTERNATIONAL.html |date=2010-09-09 }}</ref> A pronounced increase of costs and concerns about possible unexpected technical problems had discouraged potential investors and customers.

The [[People's Republic of China]] began construction of a 200-MW High Temperature Pebble bed reactor in 2012 as a successor to its [[HTR-10]].<ref>[http://www.nucnet.org/all-the-news/2013/01/07/china-begins-construction-of-first-generation-iv-htr-pm-unit Nucnet Report: 'China Begins Construction of First Generation IV HTR-PM Unit', 7 January 2013]</ref>

Also in 2012, as part of the [[Next Generation Nuclear Plant]] competition, [[Idaho National Laboratory]] approved a design similar to [[Areva]]'s prismatic block [http://us.areva.com/EN/home-3225/areva-inc-areva-htgr.html Antares reactor] as the chosen [[HTGR]] to be deployed as a prototype by 2021. It was in competition with [[General Atomics]]' [[Gas turbine modular helium reactor]] and [[Westinghouse Electric Company|Westinghouse]]'s [[Pebble Bed Modular Reactor]].<ref name="World nuclear news">{{cite web|url=http://www.world-nuclear-news.org/NN-Areva_modular_reactor_selected_for_NGNP_development-1502124.html|title=INL approves Antares design}}</ref>

[[X-energy]] was awarded a five-year $53M U.S. Department of Energy Advanced Reactor Concept Cooperative Agreement award to advance elements of their reactor development.<ref>[https://www.x-energy.com/doe-partnership]</ref>
The [[X-energy#Reactor Design|Xe-100]] is a pebble-bed modular reactor and will generate 200-MWt and approximately 76-MWe. The standard Xe-100 "four-pack" plant generates approximately 300-MWe and will fit on as few as 13 acres. All of the components for the Xe-100 will be road-transportable, and will be installed, rather than constructed, at the project site to streamline construction.<ref name="X-energy">{{cite web|url=https://www.x-energy.com/}}</ref>

==== Molten-salt reactor (MSR) ====
[[File:Molten Salt Reactor.svg|right|thumb|Molten Salt Reactor (MSR)]]
{{Main article|Molten salt reactor}}
{{see also|Liquid fluoride thorium reactor}}
A '''molten salt reactor'''<ref name="Roadmap"/> is a type of [[nuclear reactor]] where the primary [[coolant]], or even the fuel itself is a molten salt mixture. There have been many designs put forward for this type of reactor and a few prototypes built. The early concepts and many current ones rely on [[nuclear fuel]], perhaps [[uranium tetrafluoride]] (UF4) or [[thorium tetrafluoride]] (ThF4), dissolved in molten [[fluoride]] salt. The fluid would reach [[Nuclear reactor physics#Criticality|criticality]] by flowing into a core where [[graphite]] would serve as the [[neutron moderator|moderator]]. Many current concepts rely on fuel that is dispersed in a graphite matrix with the molten salt providing low pressure, high temperature cooling.

The Gen IV MSR is more accurately termed an [[epithermal neutron|epithermal reactor]] than a thermal reactor due to the average speed of the neutrons that would cause the fission events within its fuel being faster than [[thermal neutron]]s.<ref>{{cite web |url=https://inlportal.inl.gov/portal/server.pt?open=514&objID=1361&parentname=CommunityPage&parentid=10&mode=2&in_hi_userid=200&cached=true |title=Idaho National Laboratory detailing some current efforts at developing Gen. IV reactors}}</ref>

The principle of a MSR can be used for thermal, epithermal and fast reactors. Since 2005 the focus has moved towards a fast spectrum MSR (MSFR).<ref>H. Boussier, S. Delpech, V. Ghetta et Al. : The Molten Salt Reactor (MSR) in Generation IV: Overview and Perspectives, GIF SYMPOSIUM PROCEEDINGS/2012 ANNUAL REPORT, NEA No. 7141, pp95 [https://www.gen-4.org/gif/jcms/c_44720/annual-reports]
</ref>

While most MSR designs being pursued are largely derived from the 1960s [[Molten-Salt Reactor Experiment]] (MSRE), variants of molten salt technology include the conceptual ''[[Dual fluid reactor]]'' which is being designed with lead as a cooling medium but molten salt fuel, commonly as the metal chloride e.g. [[Plutonium(III) chloride]], to aid in greater "nuclear waste" closed-fuel cycle capabilities.
Other notable approaches differing substantially from MSRE include the ''[[Stable Salt Reactor]]'' (SSR) concept promoted by MOLTEX, which encases the molten salt in hundreds of the common solid [[fuel rod]]s that are already well established in the nuclear industry. This latter British design was found to be the most competitive for [[Small modular reactor]] development by a British-based consultancy firm ''Energy Process Development'' in 2015.<ref>[http://www.daretothink.org/europe-moltex-stable-salt-reactor/ Europe: Moltex’ Stable Salt Reactor]</ref><ref>[http://analysis.nuclearenergyinsider.com/moltex-energy-sees-uk-canada-smr-licensing-springboard-asia Moltex Energy sees UK, Canada SMR licensing as springboard to Asia Jun 28, 2016]</ref>

Another notable feature of the MSR is the possibility of a [[Thermal-neutron reactor|thermal spectrum]] nuclear [[Nuclear fuel cycle#Fuel cycles|waste-burner]]. Conventionally only fast spectrum reactors have been considered viable for [[Nuclear fuel cycle#Minor actinides recycling|utilization or reduction]] of the [[Spent nuclear fuel|spent nuclear stockpiles]]. The conceptual viability of a thermal waste-burner was first shown in a whitepaper by [[Seaborg Technologies]] spring 2015.<ref name="Seaborg Whitepaper 2015">{{cite web|url=https://seaborg.dk/s/Seaborg-whitepaper-2015.pdf|title=Thermal MSR waste burner benchmark}}</ref> Thermal waste-burning was achieved by replacing a fraction of the [[uranium]] in the spent nuclear fuel with [[thorium]]. The net production rate of [[transuranium element]] (e.g. [[plutonium]] and [[americium]]) is reduced below the consumption rate, thus reducing the magnitude of the [[Radioactive waste|nuclear storage problem]], without the [[nuclear proliferation]] concerns and other [[Fast-neutron reactor#Disadvantages|technical issues]] associated with a [[Fast-neutron reactor|fast reactor]].

==== Supercritical-water-cooled reactor (SCWR) ====
[[File:Supercritical-Water-Cooled Reactor.svg|right|thumb|Supercritical-Water-Cooled Reactor (SCWR)]]
{{Main article|Supercritical water reactor}}
The '''supercritical water reactor''' (SCWR)<ref name="Roadmap"/> is a [[reduced moderation water reactor]] concept that, due to the average speed of the neutrons that would cause the fission events within the fuel being faster than [[thermal neutron]]s, it is more accurately termed an [[epithermal neutron|epithermal reactor]] than a thermal reactor. It uses [[supercritical fluid|supercritical water]] as the working fluid. SCWRs are basically [[light water reactor]]s (LWR) operating at higher pressure and temperatures with a direct, once-through heat exchange cycle. As most commonly envisioned, it would operate on a direct cycle, much like a boiling water reactor ([[BWR]]), but since it uses supercritical water (not to be confused with [[Critical mass (nuclear)|critical mass]]) as the working fluid, it would have only one water phase present, which makes the supercritical heat exchange method more similar to a pressurized water reactor ([[Pressurized water reactor|PWR]]). It could operate at much higher temperatures than both current PWRs and BWRs.

Supercritical water-cooled reactors (SCWRs) are promising advanced nuclear systems because of their high [[thermal efficiency]] (i.e., about 45% vs. about 33% efficiency for current LWRs) and considerable plant simplification.

The main mission of the SCWR is generation of low-cost [[electricity]]. It is built upon two proven technologies, LWRs, which are the most commonly deployed power generating reactors in the world, and superheated [[fossil fuel]] fired [[boiler]]s, a large number of which are also in use around the world. The SCWR concept is being investigated by 32 organizations in 13 countries.{{citation needed|date=October 2012}}

Because SCWRs are water reactors they share the steam explosion and radioactive steam release hazards of BWRs and LWRs as well as the need for extremely expensive heavy duty pressure vessels, pipes, valves, and pumps. These shared problems are inherently more severe for SCWRs due to operation at higher temperatures.

A SCWR Design under development is the [[VVER]]-1700/393 (VVER-SCWR or VVER-SKD) — a Russian Supercritical-water-cooled reactor with double-inlet-core and a [[breeder reactor|breeding ratio]] of 0.95.<ref name="powertecrussia.com">{{cite web |url=http://www.powertecrussia.com/blog/tag/nuclear-power/ |title=Technology Developments & Plant Efficiency for the Russian Nuclear Power Generation Market Wednesday |date=March 24, 2010}}</ref>

=== Fast reactors ===
A [[Fast-neutron reactor|fast reactor]] directly uses the fast neutrons emitted by fission, without moderation. Unlike thermal neutron reactors, fast neutron reactors can be configured to "'''burn'''", or fission, all [[actinides]], and given enough time, therefore drastically reduce the actinides fraction in [[spent nuclear fuel]] produced by the present world fleet of thermal neutron [[light water reactor]]s, thus closing the [[nuclear fuel cycle]]. Alternatively, if configured differently, they can also [[breeder reactor|'''breed''']] more actinide fuel than they consume.

==== Gas-cooled fast reactor (GFR) ====
[[File:Gas-Cooled Fast Reactor Schemata.svg|right|thumb|Gas-Cooled Fast Reactor (GFR)]]
{{Main article|Gas-cooled fast reactor}}
The '''gas-cooled fast reactor''' (GFR)<ref name="Roadmap"/> system features a fast-neutron spectrum and closed fuel cycle for efficient conversion of [[Fertile material|fertile uranium]] and management of actinides. The reactor is [[helium]]-cooled and with an outlet temperature of 850 °C it is an evolution of the [[very-high-temperature reactor]] (VHTR) to a more sustainable fuel cycle. It will use a direct [[Brayton cycle]] [[Closed-cycle gas turbine|gas turbine]] for high thermal efficiency. Several fuel forms are being considered for their potential to operate at very high temperatures and to ensure an excellent retention of [[Nuclear fission|fission]] products: composite [[ceramic]] fuel, advanced fuel particles, or ceramic clad elements of actinide compounds. Core configurations are being considered based on pin- or plate-based fuel assemblies or prismatic blocks.

The European Sustainable Nuclear Industrial Initiative is funding three Generation IV reactor systems, one of which is a gas-cooled fast reactor, called ''Allegro'', 100 MW(t), which will be built in a central or eastern European country with construction expected to begin in 2018.<ref name="euronuclear.org">{{cite web|url=https://www.euronuclear.org/1-information/news/Gen-IV.htm |title=The European Sustainable Nuclear Industrial Initiative (ESNII) will support three Generation IV reactor systems: a sodium-cooled fast reactor, or SFR, called ''Astrid'' that is proposed by France; a gas-cooled fast reactor, GFR, called ''Allegro'' supported by central and eastern Europe; and a lead-cooled fast reactor, LFR, technology pilot called ''Myrrha'' that is proposed by Belgium. |deadurl=yes |archiveurl=https://web.archive.org/web/20131009042600/http://euronuclear.org/1-information/news/Gen-IV.htm |archivedate=2013-10-09 |df= }}</ref> The central European [[Visegrád Group]] are committed to pursuing the technology.<ref>{{cite web |url=http://www.alphagalileo.org/ViewItem.aspx?ItemId=133111&CultureCode=en |title=The V4G4 Centre of Excellence for performing joint research, development and innovation in the field of Generation-4 (G4) nuclear reactors have been established. 20 July 2013 National Center for Nuclear Research (NCBJ)}}</ref> In 2013 German, British, and French institutes finished a 3-year collaboration study on the follow on industrial scale design, known as ''GoFastR''.<ref>{{cite web|url=http://www.ist-world.org/ProjectDetails.aspx?ProjectId=5cb8f3f283574cc6b2bdbf72533172d8 |title=the European Gas cooled Fast Reactor. |deadurl=yes |archiveurl=https://web.archive.org/web/20131213091046/http://www.ist-world.org/ProjectDetails.aspx?ProjectId=5cb8f3f283574cc6b2bdbf72533172d8 |archivedate=2013-12-13 |df= }}</ref> They were funded by the EU's 7th FWP [[framework programme]], with the goal of making a sustainable VHTR.<ref>{{cite web |url=http://www.2020-horizon.com/GOFASTR-European-Gas-Cooled-Fast-Reactor%28GOFASTR%29-s312.html |title=The GOFASTR research program}}</ref>

==== Sodium-cooled fast reactor (SFR) ====
[[File:Sodium-Cooled Fast Reactor Schemata.svg|right|thumb|Pool design Sodium-Cooled Fast Reactor (SFR)]]
{{Main article|Sodium-cooled fast reactor}}
{{see also|Prototype Fast Breeder Reactor|Experimental Breeder Reactor II|S-PRISM|BN-800 reactor|Toshiba 4S|CFR-600}}

In India, the [[Fast Breeder Test Reactor]] reached criticality in October 1985. In September 2002, fuel burn-up in the FBTR for the first time reached the 100,000 megawatt-days per metric ton uranium (MWd/MTU) mark. This is considered an important milestone in breeder reactor technology. Using the experience gained from the operation of the FBTR, the [[Prototype Fast Breeder Reactor]], a 500 MWe Sodium cooled fast reactor is being built at a cost of INR 5,677 crores (~US$900 million) and is expected to be critical by June 2018. The PFBR will be followed by six more Commercial Fast Breeder Reactors (CFBRs) of 600 MWe each.

The SFR<ref name="Roadmap"/> is a project that builds on two closely related existing projects, the liquid metal [[Breeder reactor#Fast breeder reactor|fast breeder reactor]] and the [[integral fast reactor]].

The goals are to increase the efficiency of uranium usage by [[breeder reactor|breeding]] plutonium and eliminating the need for [[transuranic]] isotopes ever to leave the site. The reactor design uses an unmoderated core running on [[fast neutron]]s, designed to allow any transuranic isotope to be consumed (and in some cases used as fuel). In addition to the benefits of removing the long [[half-life]] transuranics from the waste cycle, the SFR fuel expands when the reactor overheats, and the chain reaction automatically slows down. In this manner, it is passively safe.<ref>{{cite web |url=http://www.ne.anl.gov/About/hn/logos-winter02-psr.shtml|title=Passively safe reactors rely on nature to keep them cool|author=David Baurac}}</ref>

The SFR reactor concept is cooled by liquid [[sodium]] and fueled by a metallic alloy of uranium and [[plutonium]] or [[spent nuclear fuel]], the "nuclear waste" of [[light water reactor]]s. The SFR fuel is contained in steel cladding with liquid sodium filling in the space between the clad elements which make up the fuel assembly. One of the design challenges of an SFR is the risks of handling sodium, which reacts explosively if it comes into contact with water. However, the use of liquid metal instead of water as coolant allows the system to work at atmospheric pressure, reducing the risk of leakage.

[[File:Ifr concept.jpg|thumb|375px|The sustainable fuel-cycle proposed in the 1990s [[Integral fast reactor]] concept (color), an animation of the [[pyroprocessing]] technology is also available.<ref>{{cite web |url=https://www.youtube.com/watch?v=cBThTwFhRlA |title=Historical video about the Integral Fast Reactor (IFR) concept. Uploaded by - Nuclear Engineering at Argonne}}</ref>]]
[[File:IFR concept.png|thumb|375px|IFR concept (Black and White with clearer text)]]

The European Sustainable Nuclear Industrial Initiative is funding three Generation IV reactor systems, one of which is a sodium-cooled fast reactor, called ''[[ASTRID (reactor)|ASTRID]]'', Advanced Sodium Technical Reactor for Industrial Demonstration, [[Areva]], [[Commissariat à l'énergie atomique et aux énergies alternatives|CEA]] and [[Électricité de France|EDF]] are leading the design with British collaboration.<ref>{{cite web |url=http://www.power-eng.com/articles/2010/11/areva--cea-secure.html |title=Areva, CEA secure EUR650m funding to develop ASTRID sodium-cooled Generation IV reactor 11/11/2010}}</ref><ref>{{cite web |url=http://www.powermag.com/uk-and-france-sign-landmark-civil-nuclear-cooperation-agreement/ |title=UK and France Sign Landmark Civil Nuclear Cooperation Agreement 02/22/2012 . POWERnews}}</ref> Astrid will be rated about 600 MWe and is proposed to be built in France, near to the [[Phénix]] reactor. A final decision in construction is to be made in 2019<ref name="euronuclear.org"/>

The [[China|PRC]]'s first commercial-scale, 800 MWe, fast neutron reactor, to be situated near [[Sanming]] in [[Fujian province]] will be a SFR. In 2009 an agreement was signed that would entail the Russian [[BN-800 reactor]] design to be sold to the PRC once it is completed, this would be the first time commercial-scale fast neutron reactors have ever been exported.<ref>{{cite web |url=http://www.world-nuclear-news.org/C-Joint_venture_launched_for_Chinese_fast_reactor-3004104.html |title=Joint venture launched for Chinese fast reactor}}</ref> The BN-800 reactor became operational in 2014.

The 400 MWe [[Fast Flux Test Facility]] operated successfully for ten years at the Hanford site in Washington State.

The 20 MWe [[EBR II]] operated successfully for over thirty years at the Idaho National Laboratory, until it was shut down in 1994.

GE Hitachi's [[PRISM (reactor)|PRISM]] reactor is a modernized and commercial implementation of the technology developed for the Integral Fast Reactor(IFR), developed by [[Argonne National Laboratory]] between 1984 and 1994. With the primary purpose of PRISM differing in the focus on burning up [[spent nuclear fuel]] from other reactors, rather than [[breeder reactor|breeding]] new fuel. Presented as an alternative to burying the spent fuel/waste, the design reduces the half lives of the fissionable elements present in spent nuclear fuel while generating electricity largely as a by-product.

==== Lead-cooled fast reactor (LFR) ====
[[File:Lead-Cooled Fast Reactor Schemata.svg|right|thumb|Lead-Cooled Fast Reactor (LFR)]]
{{Main article|Lead-cooled fast reactor}}
{{See also|MYRRHA}}
The '''lead-cooled fast reactor'''<ref name="Roadmap">{{cite journal|year=2002 |title=A Technology Roadmap for Generation IV Nuclear Energy Systems |last=US DOE Nuclear Energy Research Advisory Committee |volume=GIF-002-00 |url=http://nuclear.energy.gov/genIV/documents/gen_iv_roadmap.pdf |deadurl=yes |archiveurl=https://web.archive.org/web/20071129121214/http://nuclear.energy.gov/genIV/documents/gen_iv_roadmap.pdf |archivedate=2007-11-29 |df= }}</ref> features a fast-neutron-spectrum [[lead]] or [[lead]]/[[bismuth]] [[eutectic]] ([[Lead-bismuth eutectic|LBE]]) liquid-metal-cooled reactor with a closed [[Nuclear fuel cycle|fuel cycle]]. Options include a range of plant ratings, including a "battery" of 50 to 150 MW of electricity that features a very long refueling interval, a modular system rated at 300 to 400 MW, and a large monolithic plant option at 1,200 MW (The term ''battery'' refers to the long-life, factory-fabricated core, not to any provision for electrochemical energy conversion). The fuel is metal or nitride-based containing [[Fertile material|fertile uranium]] and [[transuranic]]s. The LFR is cooled by natural [[convection]] with a reactor outlet coolant temperature of 550 °C, possibly ranging up to 800 °C with advanced materials. The higher temperature enables the production of [[Thermochemical cycle|hydrogen by thermochemical processes]].

The European Sustainable Nuclear Industrial Initiative is funding three Generation IV reactor systems, one of which is a lead-cooled fast reactor that is also an [[Subcritical reactor|accelerator-driven sub-critical]] reactor, called ''[[MYRRHA]]'', 100 MW(t), which will be built in [[Belgium]] with construction expected to begin after 2014 and the industrial scale version, known as ''Alfred'', slated to be constructed sometime after 2017. A reduced-power model of Myrrha called ''Guinevere'' was started up at [[Mol, Belgium|Mol]] in March 2009.<ref name="euronuclear.org"/> In 2012 the research team reported that Guinevere was operational.<ref>{{cite news|last1=Hellemans|first1=Alexander|title=Reactor-Accelerator Hybrid Achieves Successful Test Run|url=http://news.sciencemag.org/physics/2012/01/reactor-accelerator-hybrid-achieves-successful-test-run|accessdate=29 December 2014|work=Science Insider|date=12 January 2012}}</ref>

Two other lead-cooled fast reactors under development are the SVBR-100, a modular 100 MWe lead-bismuth cooled fast neutron reactor concept designed by OKB [[Gidropress]] in Russia and the [[BREST (Reactor)|BREST-OD-300]] (Lead-cooled fast reactor) 300 MWe, to be developed after the SVBR-100, and built over 2016-20, it will dispense with the [[Uranium-238|fertile blanket]] around the core and will supersede the sodium cooled [[BN-600 reactor]] design, to purportedly give enhanced proliferation resistance.<ref name="powertecrussia.com"/>

== Advantages and disadvantages ==
Relative to current nuclear power plant technology, the claimed benefits for 4th generation reactors include:
* Nuclear waste that remains radioactive for a few centuries instead of millennia<ref>{{cite web |title=Strategies to Address Global Warming |url=http://www.columbia.edu/~jeh1/mailings/2009/20090713_Strategies.pdf}}</ref>
* 100–300 times more energy yield from the same amount of nuclear fuel<ref>{{cite web |title=4th Generation Nuclear Power |url=http://www.ossfoundation.us/projects/energy/nuclear}}</ref>
* Broader range of fuels, and even unencapsulated raw fuels (non-pebble [[Molten Salt Reactor|MSR]], [[Liquid fluoride thorium reactor|LFTR]]).
* In some reactors, the ability to consume existing nuclear waste in the production of electricity, that is, a Closed [[nuclear fuel cycle]]. This strengthens the argument to deem [[nuclear power as renewable energy]].
* Improved operating safety features, such as (depending on design) avoidance of pressurized operation, automatic passive (unpowered, uncommanded) reactor shutdown, avoidance of water cooling and the associated risks of loss of water (leaks or boiling) and hydrogen generation/explosion and contamination of coolant water.

Nuclear reactors do not emit CO2 during operation, although like all [[low carbon power]] sources, the mining and construction phase can result in CO2 emissions, if energy sources which are not carbon neutral (such as fossil fuels), or CO2 emitting cements are used during the construction process.
A 2012 [[Yale University]] review published in the Journal of Industrial Ecology analyzing {{CO2}} [[life cycle assessment]] (LCA) emissions from [[nuclear power]] determined that:<ref name="Warner + Heath, JoIE">Warner, Ethan S.; Heath, Garvin A. [http://onlinelibrary.wiley.com/doi/10.1111/j.1530-9290.2012.00472.x/full Life Cycle Greenhouse Gas Emissions of Nuclear Electricity Generation: Systematic Review and Harmonization], ''Journal of Industrial Ecology'', [[Yale University]], published online April 17, 2012, {{doi|10.1111/j.1530-9290.2012.00472.x}}</ref>
{{Quote|The collective LCA literature indicates that life cycle [[Greenhouse gas|GHG]] [greenhouse gas] emissions from nuclear power are only a fraction of traditional fossil sources and comparable to renewable technologies.}}
Although the paper primarily dealt with data from [[Generation II reactor]]s, and did not analyze the {{CO2}} emissions by 2050 of the presently under construction [[Generation III reactor]]s, it did summarize the Life Cycle Assessment findings of in development reactor technologies.{{Quote|FBRs ['[[Fast Breeder Reactor]]s'] have been evaluated in the LCA literature. The limited literature that evaluates this potential future technology reports [[median]] life cycle GHG emissions... similar to or lower than LWRs [Gen II [[light water reactor]]s] and purports to consume little or no [[uranium market|uranium ore]].}}

A specific risk of the sodium-cooled fast reactor is related to using metallic sodium as a coolant. In case of a breach, sodium explosively reacts with water. Fixing breaches may also prove dangerous, as the cheapest noble gas [[argon]] is also used to prevent sodium oxidation. Argon, like helium, can displace oxygen in the air and can pose [[hypoxia (environmental)|hypoxia]] concerns, so workers may be exposed to this additional risk. This is a pertinent problem as demonstrated by the events at the [[LMFBR|loop type]] [[Monju Nuclear Power Plant|Prototype Fast Breeder Reactor Monju]] at Tsuruga, Japan.<ref>{{cite news |title=Japan Strains to Fix a Reactor Damaged Before Quake |url=https://www.nytimes.com/2011/06/18/world/asia/18japan.html | work=The New York Times | first=Hiroko |last=Tabuchi |date=17 June 2011}}</ref>
Using lead or molten salts mitigates this problem by making the coolant less reactive and allowing a high freezing temperature and low pressure in case of a leak. Disadvantages of lead compared to sodium are much higher viscosity, much higher density, lower heat capacity, and more radioactive neutron activation products.

In many cases, there is already a large amount of experience built up with numerous proof of concept Gen IV designs. For example, the reactors at [[Fort St. Vrain Generating Station]] and [[HTR-10]] are similar to the proposed Gen IV [[VHTR]] designs, and the [[LMFBR|pool type]] [[EBR-II]], [[Phénix]] and [[BN-600]] reactor are similar to the proposed pool type Gen IV Sodium Cooled Fast reactors being designed.

== Table of designs ==

{| class=wikitable
|+ Summary of designs for generation IV reactors<ref>https://www.gen-4.org/gif/upload/docs/application/pdf/2013-09/gif_rd_outlook_for_generation_iv_nuclear_energy_systems.pdf</ref>
|-
! System
! Neutron Spectrum
! Coolant
! Temperature (°C)
! Fuel Cycle
! Size (MW)
!Example developers
|-
| [[Very-high-temperature reactor|VHTR]]
| Thermal
| Helium
| 900–1000
| Open
| 250–300
|[[Japan Atomic Energy Agency|JAEA]] ([[High-temperature engineering test reactor|HTTR]]), [[Tsinghua University]] ([[HTR-10]]), [[X-energy]]<ref name="energy.gov">{{cite web|title=Energy Department Announces New Investments in Advanced Nuclear Power Reactors...|url=https://www.energy.gov/articles/energy-department-announces-new-investments-advanced-nuclear-power-reactors-help-meet|website=[[United States Department of Energy|US Department of Energy]]|accessdate=16 January 2016}}</ref>
|-
| [[Sodium-cooled fast reactor|SFR]]
| Fast
| Sodium
| 550
| Closed
| 30–150, 300–1500, 1000–2000
|[[TerraPower]] ([[Traveling wave reactor|TWR]]), [[Toshiba]] ([[Toshiba 4S|4S]]), [[GE Hitachi Nuclear Energy]] ([[PRISM (reactor)|PRISM]])
|-
| [[Supercritical water reactor|SCWR]]
| Thermal or fast
| Water
| 510–625
| Open or closed
| 300–700, 1000–1500
|
|-
| [[Gas-cooled fast reactor|GFR]]
| Fast
| Helium
| 850
| Closed
| 1200
|[[Energy Multiplier Module]]
|-
| [[Lead-cooled fast reactor|LFR]]
| Fast
| Lead
| 480–800
| Closed
| 20–180, 300–1200, 600–1000
|
|-
| [[Molten salt reactor|MSR]]
| Fast or thermal
| Fluoride or chloride salts
| 700–800
| Closed
| 250, 1000
|[[Seaborg Technologies]], [[TerraPower]], [[Stable Salt Reactor|Moltex Energy]], [[Flibe Energy]] ([[Liquid fluoride thorium reactor|LFTR]]), [[Transatomic Power]], Thorium Tech Solution ([[Fuji Molten Salt Reactor|FUJI MSR]]), Terrestrial Energy ([[IMSR]]), [[Southern Company Services|Southern Company]]<ref name="energy.gov"/>
|-
| [[Dual fluid reactor|DFR]]
| Fast
| Lead
| 1000
| Closed
| 500–1500
| Institute for Solid-State Nuclear Physics<ref name=ifk>{{cite web |url=https://festkoerper-kernphysik.de/dfr.pdf |title=Dual Fluid Reactor - IFK |date=2013-06-16 |website=festkoerper-kernphysik.de |publisher= Institut für Festkörper-Kernphysik |format=PDF |location=Berlin, Germany |access-date=2017-08-28}}</ref>
|}

== See also ==
{{portal|Energy|Nuclear technology}}
{{colbegin}}
* [[Nuclear reactor]]
* [[Nuclear material]]
* [[Nuclear physics]]
* [[List of reactor types#Reactor types|List of reactor types]]
* [[Generation II reactor]]
* [[Generation III reactor]]
* [[Integral Fast Reactor]]
* [[Liquid fluoride thorium reactor]]
* [[Breeder reactor]]
* [[Small modular reactor]]
* [[List of nuclear reactors]]
{{colend}}

==References==
{{Reflist|30em}}

== External links ==
* [https://inlportal.inl.gov/portal/server.pt?open=514&objID=1361&parentname=CommunityPage&parentid=10&mode=2&in_hi_userid=200&cached=true Article from Idaho National Laboratory detailing some current efforts at developing Gen. IV reactors.]
* [http://www.gen-4.org/ Generation IV International Forum (GIF)]
* [https://web.archive.org/web/20070205115654/http://nuclear.energy.gov/genIV/neGenIV1.html U.S. Department of Energy Office of Nuclear Energy, Science and Technology]
* [https://web.archive.org/web/20060512033030/http://www.engr.utk.edu/nuclear/colloquia/slides/Gen%20IV%20U-Tenn%20Presentation.pdf Gen IV presentation]
* [http://www.ecology.at/ecology/files/pr577_1.pdf Science or Fiction - Is there a Future for Nuclear?] (Nov. 2007) - A publication from the Austrian [[Ecology Institute (Austria)|Ecology Institute]] about 'Generation IV' and Fusion reactors.
* {{cite web |url=http://memagazine.asme.org/Articles/2011/December/Nuclear_Power_After_Fukushima.cfm |title=Nuclear Power After Fukushima |author=Gail H. Marcus |date=December 2011 |work=Mechanical Engineering (the magazine of [[ASME]]) |accessdate=23 January 2012}} "In the wake of a severe plant accident, advanced reactor designs are getting renewed attention."
* [http://www.itheo.org/ International Thorium Energy Organisation - www.IThEO.org]
* [http://www.ithec.org/ International Thorium Energy Committee - iThEC]

{{Nuclear fission reactors}}

[[Category:Nuclear power reactor types]]
[[Category:Idaho National Laboratory]]

Benutzer:Snackroeg/Kernreaktoren der Generation 5

2018-05-14T00:44:55Z

Boundarylayer:

{{update|date=October 2017}}
[[File:GenIVRoadmap-en.svg|thumb|480px|Nuclear Energy Systems Deployable no later than 2030 and offering significant advances in sustainability, safety and reliability, and economics]]

'''Generation IV reactors''' ('''Gen IV''') are a set of [[nuclear reactor]] designs currently being researched for commercial applications by the Generation IV International Forum, with [[Technology readiness level]]s varying between the level requiring a demonstration, to economical competitive implementation.<ref>{{Cite journal|last=Locatelli|first=Giorgio|last2=Mancini|first2=Mauro|last3=Todeschini|first3=Nicola|date=2013-10-01|title=Generation IV nuclear reactors: Current status and future prospects|url=http://www.sciencedirect.com/science/article/pii/S0301421513006083|journal=Energy Policy|volume=61|pages=1503–1520|doi=10.1016/j.enpol.2013.06.101}}</ref> They are motivated by a variety of goals including improved safety, sustainability, efficiency, and cost.

The most developed Gen IV reactor design, the [[sodium fast reactor]], has received the greatest share of funding over the years, with the principle Gen IV aspect of the design, relating in largest part to the development of a sustainable closed [[Nuclear_fuel_cycle#Plutonium_cycle|fuel cycle]] for the reactor. Amongst nuclear engineers the [[molten-salt reactor]], the least developed and funded technology, is considered as potentially having the greatest [[Passive nuclear safety|inherent safety]] of the six models.<ref>[https://www.scientificamerican.com/article/can-sodium-save-nuclear-power/ Can Sodium Save Nuclear Power? Scientific American]</ref><ref>{{cite journal |last1=Moir |first1=Ralph |last2=Teller |first2=Edward |year=2005 |title=Thorium-Fueled Underground Power Plant Based on Molten Salt Technology |journal=Nuclear Technology |volume=151 |issue=3 |pages=334–340 |publisher=[[American Nuclear Society]] |url=http://www.new.ans.org/pubs/journals/nt/a_3655 |accessdate=March 22, 2012 }}</ref> While the [[hydrogen economy]], the use of hydrogen to produce [[Carbon-neutral fuel]]s, is deemed as strengthening the economic case for the two most efficient models, the [[Very-high-temperature reactor|high temperature reactor]] designs.<ref>[https://www.sciencedirect.com/science/article/pii/S0301421513006083 Generation IV nuclear reactors: Current status and future prospects doi.org/10.1016/j.enpol.2013.06.101]</ref>

The majority of the 6 designs are generally not expected to be available for commercial construction until 2020–30.<ref name="Generation IV">[http://www.world-nuclear.org/info/Nuclear-Fuel-Cycle/Power-Reactors/Generation-IV-Nuclear-Reactors/]</ref> Presently the majority of reactors in operation around the world are considered [[Generation II reactor|second generation reactor]] systems, as the vast majority of the [[Nuclear reactor#Classification by generation|first generation]] systems were retired some time ago, and there are only a dozen or so [[Generation III reactor]]s in operation as of 2014.
[[Nuclear reactor#Generation V+ reactors|Generation V reactors]] refer to reactors that are purely theoretical and are therefore not yet considered feasible in the short term, resulting in limited [[R&D]] funding.

== History ==
The Generation IV International Forum (GIF) is "a co-operative international endeavour which was set up to carry out the research and development needed to establish the feasibility and performance capabilities of the next generation nuclear energy systems."<ref>{{Cite web|url=https://www.gen-4.org/gif/jcms/c_9260/public|title=GIF Portal - Home - Public|website=www.gen-4.org|access-date=2016-07-25}}</ref> It was founded in 2001. Currently active members of the Generation IV International Forum (GIF) include: [[Australia]], [[Canada]], [[China]], the [[European Atomic Energy Community]] (Euratom), [[France]], [[Japan]], [[Russia]], [[South Africa]], [[South Korea]], [[Switzerland]], and the [[United States]]. The non-active members are [[Argentina]], [[Brazil]], and the [[United Kingdom]].<ref name="gen-4">{{cite web|url=https://www.gen-4.org/gif/jcms/c_9492/members|title=GIF Membership|website=gen-4.org|accessdate=28 October 2014}}</ref> Switzerland joined in 2002, Euratom in 2003, and China and Russia in 2006. The remaining countries (excluding Australia) were founding members.<ref name="gen-4" />

The 36th GIF meeting in [[Brussels]] was held in November 2013.<ref>{{cite web|url=https://www.energy.gov/ne/articles/generation-iv-international-forum-updates-technology-roadmap-and-builds-future|title=generation IV international forum updates technology roadmap and builds future. DOE}}</ref><ref>{{cite web|url=http://events.r20.constantcontact.com/register/event?llr=mscrkjkab&oeidk=a07e7melf609716b2c6 |title=The Generation IV international forum holds their 36th meeting on Monday 18th Nov 2013 in Brussels. }}{{dead link|date=January 2017 |bot=InternetArchiveBot |fix-attempted=yes }}</ref> The ''Technology Roadmap Update for Generation IV Nuclear Energy Systems'' was published in January 2014 which details R&D objectives for the next decade.<ref>[https://web.archive.org/web/20140625102915/https://www.gen-4.org/gif/upload/docs/application/pdf/2014-03/gif-tru2014.pdf Technology Roadmap Update for Generation IV Nuclear Energy Systems]</ref> A breakdown of the reactor designs being researched by each forum member has been made available.<ref>[https://web.archive.org/web/20140708023538/https://www.gen-4.org/gif/upload/docs/application/pdf/2014-03/gif_overview_presentation_v9_final3_web.pdf Generation IV International Forum, overview, John E. Kelly, page 15]</ref>

[[Nuclear power in Australia|Australia]] joined the forum in 2016.<ref>https://archive.is/20160907131656/https://www.gen-4.org/gif/jcms/c_71564/australia-joins-the-generation-iv-international-forum</ref>

In January 2018, it was reported that "the first installation of the pressure vessel cover of the world's first Gen IV reactor" had been completed on the [[HTR-PM]].<ref>http://www.world-nuclear-news.org/NN-First-HTR-PM-vessel-head-in-place-0401185.html</ref>

== Reactor types ==
Many reactor types were considered initially; however, the list was downsized to focus on the most promising technologies and those that could most likely meet the goals of the Gen IV initiative.<ref name="Generation IV"/> Three systems are nominally [[thermal reactor]]s and four are [[fast reactor]]s. The Very High Temperature Reactor (VHTR) is also being researched for potentially providing high quality process heat for [[thermochemical cycle|hydrogen production]]. The fast reactors offer the possibility of burning [[actinides]] to further reduce waste and of being able to "[[breeder reactor|breed more fuel]]" than they consume. These systems offer significant advances in sustainability, safety and reliability, economics, proliferation resistance (depending on perspective) and physical protection.

=== Thermal reactors ===
A [[Thermal-neutron reactor|thermal reactor]] is a [[nuclear reactor]] that uses slow or [[thermal neutrons]]. A [[neutron moderator]] is used to slow the [[neutron]]s emitted by fission to make them more likely to be captured by the fuel.

==== Very-high-temperature reactor (VHTR) ====
[[File:Very High Temperature Reactor.svg|right|thumb|Very-High-Temperature Reactor (VHTR)]]
{{Main article|Very high temperature reactor}}
{{see also|Fort St. Vrain Generating Station|High-temperature engineering test reactor|HTR-10}}
The '''very high temperature reactor''' concept uses a [[graphite]]-moderated core with a once-through [[uranium]] fuel cycle, using helium or molten salt as the [[Very high temperature reactor#Coolant|coolant]]. This reactor design envisions an outlet temperature of 1,000 °C. The reactor core can be either a prismatic-block or a [[pebble bed reactor]] design. The high temperatures enable applications such as process heat or [[hydrogen]] production via the thermochemical [[Sulfur-iodine cycle|iodine-sulfur]] process. It would also be [[Passive nuclear safety|passively safe]].

The planned construction of the first VHTR, the South African PBMR ([[pebble bed modular reactor]]), lost government funding in February, 2010.<ref>[http://www.powergenworldwide.com/index/display/articledisplay/6322207443/articles/power-engineering-international/volume-18/Issue_3/regulars/world-news/INTERNATIONAL.html South Africa to stop funding Pebble Bed nuclear reactor] {{webarchive|url=https://web.archive.org/web/20100909172743/http://www.powergenworldwide.com/index/display/articledisplay/6322207443/articles/power-engineering-international/volume-18/Issue_3/regulars/world-news/INTERNATIONAL.html |date=2010-09-09 }}</ref> A pronounced increase of costs and concerns about possible unexpected technical problems had discouraged potential investors and customers.

The [[Peoples Republic of China]] began construction of a 200-MW High Temperature Pebble bed reactor in 2012 as a successor to its [[HTR-10]].<ref>[http://www.nucnet.org/all-the-news/2013/01/07/china-begins-construction-of-first-generation-iv-htr-pm-unit Nucnet Report: 'China Begins Construction of First Generation IV HTR-PM Unit', 7 January 2013]</ref>

Also in 2012, as part of the [[Next Generation Nuclear Plant]] competition, [[Idaho National Laboratory]] approved a design similar to [[Areva]]'s prismatic block [http://us.areva.com/EN/home-3225/areva-inc-areva-htgr.html Antares reactor] as the chosen [[HTGR]] to be deployed as a prototype by 2021. It was in competition with [[General Atomics]]' [[Gas turbine modular helium reactor]] and [[Westinghouse Electric Company|Westinghouse]]'s [[Pebble Bed Modular Reactor]].<ref name="World nuclear news">{{cite web|url=http://www.world-nuclear-news.org/NN-Areva_modular_reactor_selected_for_NGNP_development-1502124.html|title=INL approves Antares design}}</ref>

[[X-energy]] was awarded a five-year $53M U.S. Department of Energy Advanced Reactor Concept Cooperative Agreement award to advance elements of their reactor development.<ref>[https://www.x-energy.com/doe-partnership]</ref>
The [[X-energy#Reactor Design|Xe-100]] is a pebble-bed modular reactor and will generate 200-MWt and approximately 76-MWe. The standard Xe-100 "four-pack" plant generates approximately 300-MWe and will fit on as few as 13 acres. All of the components for the Xe-100 will be road-transportable, and will be installed, rather than constructed, at the project site to streamline construction.<ref name="X-energy">{{cite web|url=https://www.x-energy.com/}}</ref>

==== Molten-salt reactor (MSR) ====
[[File:Molten Salt Reactor.svg|right|thumb|Molten Salt Reactor (MSR)]]
{{Main article|Molten salt reactor}}
{{see also|Liquid fluoride thorium reactor}}
A '''molten salt reactor'''<ref name="Roadmap"/> is a type of [[nuclear reactor]] where the primary [[coolant]], or even the fuel itself is a molten salt mixture. There have been many designs put forward for this type of reactor and a few prototypes built. The early concepts and many current ones rely on [[nuclear fuel]], perhaps [[uranium tetrafluoride]] (UF4) or [[thorium tetrafluoride]] (ThF4), dissolved in molten [[fluoride]] salt. The fluid would reach [[Nuclear reactor physics#Criticality|criticality]] by flowing into a core where [[graphite]] would serve as the [[neutron moderator|moderator]]. Many current concepts rely on fuel that is dispersed in a graphite matrix with the molten salt providing low pressure, high temperature cooling.

The Gen IV MSR is more accurately termed an [[epithermal neutron|epithermal reactor]] than a thermal reactor due to the average speed of the neutrons that would cause the fission events within its fuel being faster than [[thermal neutron]]s.<ref>{{cite web |url=https://inlportal.inl.gov/portal/server.pt?open=514&objID=1361&parentname=CommunityPage&parentid=10&mode=2&in_hi_userid=200&cached=true |title=Idaho National Laboratory detailing some current efforts at developing Gen. IV reactors}}</ref>

The principle of a MSR can be used for thermal, epithermal and fast reactors. Since 2005 the focus has moved towards a fast spectrum MSR (MSFR).<ref>H. Boussier, S. Delpech, V. Ghetta et Al. : The Molten Salt Reactor (MSR) in Generation IV: Overview and Perspectives, GIF SYMPOSIUM PROCEEDINGS/2012 ANNUAL REPORT, NEA No. 7141, pp95 [https://www.gen-4.org/gif/jcms/c_44720/annual-reports]
</ref>

While most MSR designs being pursued are largely derived from the 1960s [[Molten-Salt Reactor Experiment]] (MSRE), variants of molten salt technology include the conceptual ''[[Dual fluid reactor]]'' which is being designed with lead as a cooling medium but molten salt fuel, commonly as the metal chloride e.g. [[Plutonium(III) chloride]], to aid in greater "nuclear waste" closed-fuel cycle capabilities.
Other notable approaches differing substantially from MSRE include the ''[[Stable Salt Reactor]]''(SSR) concept promoted by MOLTEX, which encases the molten salt in hundreds of the common solid [[fuel rod]]s that are already well established in the nuclear industry. This latter British design was found to be the most competitive for [[Small modular reactor]] development by a British-based consultancy firm ''Energy Process Development'' in 2015.<ref>[http://www.daretothink.org/europe-moltex-stable-salt-reactor/ Europe: Moltex’ Stable Salt Reactor]</ref><ref>[http://analysis.nuclearenergyinsider.com/moltex-energy-sees-uk-canada-smr-licensing-springboard-asia Moltex Energy sees UK, Canada SMR licensing as springboard to Asia Jun 28, 2016]</ref>

Another notable feature of the MSR is the possibility of a [[Thermal-neutron reactor|thermal spectrum]] nuclear [[Nuclear fuel cycle#Fuel cycles|waste-burner]]. Conventionally only fast spectrum reactors have been considered viable for [[Nuclear fuel cycle#Minor actinides recycling|utilization or reduction]] of the [[Spent nuclear fuel|spent nuclear stockpiles]]. The conceptual viability of a thermal waste-burner was first shown in a whitepaper by [[Seaborg Technologies]] spring 2015.<ref name="Seaborg Whitepaper 2015">{{cite web|url=https://seaborg.dk/s/Seaborg-whitepaper-2015.pdf|title=Thermal MSR waste burner benchmark}}</ref> Thermal waste-burning was achieved by replacing a fraction of the [[uranium]] in the spent nuclear fuel with [[thorium]]. The net production rate of [[transuranium element]] (e.g. [[plutonium]] and [[americium]]) is reduced below the consumption rate, thus reducing the magnitude of the [[Radioactive waste|nuclear storage problem]]. Without the [[nuclear proliferation]] concerns and other [[Fast-neutron reactor#Disadvantages|technical issues]] associated with a [[Fast-neutron reactor|fast reactor]].

==== Supercritical-water-cooled reactor (SCWR) ====
[[File:Supercritical-Water-Cooled Reactor.svg|right|thumb|Supercritical-Water-Cooled Reactor (SCWR)]]
{{Main article|Supercritical water reactor}}
The '''supercritical water reactor''' (SCWR)<ref name="Roadmap"/> is a [[reduced moderation water reactor]] concept that, due to the average speed of the neutrons that would cause the fission events within the fuel being faster than [[thermal neutron]]s, it is more accurately termed an [[epithermal neutron|epithermal reactor]] than a thermal reactor. It uses [[supercritical fluid|supercritical water]] as the working fluid. SCWRs are basically [[light water reactor]]s (LWR) operating at higher pressure and temperatures with a direct, once-through heat exchange cycle. As most commonly envisioned, it would operate on a direct cycle, much like a boiling water reactor ([[BWR]]), but since it uses supercritical water (not to be confused with [[Critical mass (nuclear)|critical mass]]) as the working fluid, it would have only one water phase present, which makes the supercritical heat exchange method more similar to a pressurized water reactor ([[Pressurized water reactor|PWR]]). It could operate at much higher temperatures than both current PWRs and BWRs.

Supercritical water-cooled reactors (SCWRs) are promising advanced nuclear systems because of their high [[thermal efficiency]] (i.e., about 45% vs. about 33% efficiency for current LWRs) and considerable plant simplification.

The main mission of the SCWR is generation of low-cost [[electricity]]. It is built upon two proven technologies, LWRs, which are the most commonly deployed power generating reactors in the world, and superheated [[fossil fuel]] fired [[boiler]]s, a large number of which are also in use around the world. The SCWR concept is being investigated by 32 organizations in 13 countries.{{citation needed|date=October 2012}}

Because SCWRs are water reactors they share the steam explosion and radioactive steam release hazards of BWRs and LWRs as well as the need for extremely expensive heavy duty pressure vessels, pipes, valves, and pumps. These shared problems are inherently more severe for SCWRs due to operation at higher temperatures.

A SCWR Design under development is the [[VVER]]-1700/393 (VVER-SCWR or VVER-SKD) — a Russian Supercritical-water-cooled reactor with double-inlet-core and a [[breeder reactor|breeding ratio]] of 0.95.<ref name="powertecrussia.com">{{cite web |url=http://www.powertecrussia.com/blog/tag/nuclear-power/ |title=Technology Developments & Plant Efficiency for the Russian Nuclear Power Generation Market Wednesday |date=March 24, 2010}}</ref>

=== Fast reactors ===
A [[Fast-neutron reactor|fast reactor]] directly uses the fast neutrons emitted by fission, without moderation. Unlike thermal neutron reactors, fast neutron reactors can be configured to "'''burn'''", or fission, all [[actinides]], and given enough time, therefore drastically reduce the actinides fraction in [[spent nuclear fuel]] produced by the present world fleet of thermal neutron [[light water reactor]]s, thus closing the [[nuclear fuel cycle]]. Alternatively, if configured differently, they can also [[breeder reactor|'''breed''']] more actinide fuel than they consume.

==== Gas-cooled fast reactor (GFR) ====
[[File:Gas-Cooled Fast Reactor Schemata.svg|right|thumb|Gas-Cooled Fast Reactor (GFR)]]
{{Main article|Gas-cooled fast reactor}}
The '''gas-cooled fast reactor''' (GFR)<ref name="Roadmap"/> system features a fast-neutron spectrum and closed fuel cycle for efficient conversion of [[Fertile material|fertile uranium]] and management of actinides. The reactor is [[helium]]-cooled and with an outlet temperature of 850 °C it is an evolution of the [[very-high-temperature reactor]] (VHTR) to a more sustainable fuel cycle. It will use a direct [[Brayton cycle]] [[Closed-cycle gas turbine|gas turbine]] for high thermal efficiency. Several fuel forms are being considered for their potential to operate at very high temperatures and to ensure an excellent retention of [[Nuclear fission|fission]] products: composite [[ceramic]] fuel, advanced fuel particles, or ceramic clad elements of actinide compounds. Core configurations are being considered based on pin- or plate-based fuel assemblies or prismatic blocks.

The European Sustainable Nuclear Industrial Initiative is funding three Generation IV reactor systems, one of which is a gas-cooled fast reactor, called ''Allegro'', 100 MW(t), which will be built in a central or eastern European country with construction expected to begin in 2018.<ref name="euronuclear.org">{{cite web|url=https://www.euronuclear.org/1-information/news/Gen-IV.htm |title=The European Sustainable Nuclear Industrial Initiative (ESNII) will support three Generation IV reactor systems: a sodium-cooled fast reactor, or SFR, called ''Astrid'' that is proposed by France; a gas-cooled fast reactor, GFR, called ''Allegro'' supported by central and eastern Europe; and a lead-cooled fast reactor, LFR, technology pilot called ''Myrrha'' that is proposed by Belgium. |deadurl=yes |archiveurl=https://web.archive.org/web/20131009042600/http://euronuclear.org/1-information/news/Gen-IV.htm |archivedate=2013-10-09 |df= }}</ref> The central European [[Visegrád Group]] are committed to pursuing the technology.<ref>{{cite web |url=http://www.alphagalileo.org/ViewItem.aspx?ItemId=133111&CultureCode=en |title=The V4G4 Centre of Excellence for performing joint research, development and innovation in the field of Generation-4 (G4) nuclear reactors have been established. 20 July 2013 National Center for Nuclear Research (NCBJ)}}</ref> In 2013 German, British, and French institutes finished a 3-year collaboration study on the follow on industrial scale design, known as ''GoFastR''.<ref>{{cite web|url=http://www.ist-world.org/ProjectDetails.aspx?ProjectId=5cb8f3f283574cc6b2bdbf72533172d8 |title=the European Gas cooled Fast Reactor. |deadurl=yes |archiveurl=https://web.archive.org/web/20131213091046/http://www.ist-world.org/ProjectDetails.aspx?ProjectId=5cb8f3f283574cc6b2bdbf72533172d8 |archivedate=2013-12-13 |df= }}</ref> They were funded by the EU's 7th FWP [[framework programme]], with the goal of making a sustainable VHTR.<ref>{{cite web |url=http://www.2020-horizon.com/GOFASTR-European-Gas-Cooled-Fast-Reactor%28GOFASTR%29-s312.html |title=The GOFASTR research program}}</ref>

==== Sodium-cooled fast reactor (SFR) ====
[[File:Sodium-Cooled Fast Reactor Schemata.svg|right|thumb|Pool design Sodium-Cooled Fast Reactor (SFR)]]
{{Main article|Sodium-cooled fast reactor}}
{{see also|Prototype Fast Breeder Reactor|Experimental Breeder Reactor II|S-PRISM|BN-800 reactor|Toshiba 4S|CFR-600}}

In India, the [[Fast Breeder Test Reactor]] reached criticality in October 1985. In September 2002, fuel burn-up in the FBTR for the first time reached the 100,000 megawatt-days per metric ton uranium (MWd/MTU) mark. This is considered an important milestone in breeder reactor technology. Using the experience gained from the operation of the FBTR, the [[Prototype Fast Breeder Reactor]], a 500 MWe Sodium cooled fast reactor is being built at a cost of INR 5,677 crores (~US$900 million) and is expected to be critical by June 2018. The PFBR will be followed by six more Commercial Fast Breeder Reactors (CFBRs) of 600 MWe each.

The SFR<ref name="Roadmap"/> is a project that builds on two closely related existing projects, the liquid metal [[Breeder reactor#Fast breeder reactor|fast breeder reactor]] and the [[integral fast reactor]].

The goals are to increase the efficiency of uranium usage by [[breeder reactor|breeding]] plutonium and eliminating the need for [[transuranic]] isotopes ever to leave the site. The reactor design uses an unmoderated core running on [[fast neutron]]s, designed to allow any transuranic isotope to be consumed (and in some cases used as fuel). In addition to the benefits of removing the long [[half-life]] transuranics from the waste cycle, the SFR fuel expands when the reactor overheats, and the chain reaction automatically slows down. In this manner, it is passively safe.<ref>{{cite web |url=http://www.ne.anl.gov/About/hn/logos-winter02-psr.shtml|title=Passively safe reactors rely on nature to keep them cool|author=David Baurac}}</ref>

The SFR reactor concept is cooled by liquid [[sodium]] and fueled by a metallic alloy of uranium and [[plutonium]] or [[spent nuclear fuel]], the "nuclear waste" of [[light water reactor]]s. The SFR fuel is contained in steel cladding with liquid sodium filling in the space between the clad elements which make up the fuel assembly. One of the design challenges of an SFR is the risks of handling sodium, which reacts explosively if it comes into contact with water. However, the use of liquid metal instead of water as coolant allows the system to work at atmospheric pressure, reducing the risk of leakage.

[[File:Ifr concept.jpg|thumb|375px|The sustainable fuel-cycle proposed in the 1990s [[Integral fast reactor]] concept (color), an animation of the [[pyroprocessing]] technology is also available.<ref>{{cite web |url=https://www.youtube.com/watch?v=cBThTwFhRlA |title=Historical video about the Integral Fast Reactor (IFR) concept. Uploaded by - Nuclear Engineering at Argonne}}</ref>]]
[[File:IFR concept.png|thumb|375px|IFR concept (Black and White with clearer text)]]

The European Sustainable Nuclear Industrial Initiative is funding three Generation IV reactor systems, one of which is a sodium-cooled fast reactor, called ''[[ASTRID (reactor)|ASTRID]]'', Advanced Sodium Technical Reactor for Industrial Demonstration, [[Areva]], [[Commissariat à l'énergie atomique et aux énergies alternatives|CEA]] and [[Électricité de France|EDF]] are leading the design with British collaboration.<ref>{{cite web |url=http://www.power-eng.com/articles/2010/11/areva--cea-secure.html |title=Areva, CEA secure EUR650m funding to develop ASTRID sodium-cooled Generation IV reactor 11/11/2010}}</ref><ref>{{cite web |url=http://www.powermag.com/uk-and-france-sign-landmark-civil-nuclear-cooperation-agreement/ |title=UK and France Sign Landmark Civil Nuclear Cooperation Agreement 02/22/2012 . POWERnews}}</ref> Astrid will be rated about 600 MWe and is proposed to be built in France, near to the [[Phénix]] reactor. A final decision in construction is to be made in 2019<ref name="euronuclear.org"/>

The [[China|PRC]]'s first commercial-scale, 800 MWe, fast neutron reactor, to be situated near [[Sanming]] in [[Fujian province]] will be a SFR. In 2009 an agreement was signed that would entail the Russian [[BN-800 reactor]] design to be sold to the PRC once it is completed, this would be the first time commercial-scale fast neutron reactors have ever been exported.<ref>{{cite web |url=http://www.world-nuclear-news.org/C-Joint_venture_launched_for_Chinese_fast_reactor-3004104.html |title=Joint venture launched for Chinese fast reactor}}</ref> The BN-800 reactor became operational in 2014.

The 400 MWe [[Fast Flux Test Facility]] operated successfully for ten years at the Hanford site in Washington State.

The 20 MWe [[EBR II]] operated successfully for over thirty years at the Idaho National Laboratory, until it was shut down in 1994.

GE Hitachi's [[PRISM (reactor)|PRISM]] reactor is a modernized and commercial implementation of the technology developed for the Integral Fast Reactor(IFR), developed by [[Argonne National Laboratory]] between 1984 and 1994. With the primary purpose of PRISM differing in the focus on burning up [[spent nuclear fuel]] from other reactors, rather than [[breeder reactor|breeding]] new fuel. Presented as an alternative to burying the spent fuel/waste. The design reduces the half lives of the fissionable elements present in spent nuclear fuel while generating electricity largely as a by-product.

==== Lead-cooled fast reactor (LFR) ====
[[File:Lead-Cooled Fast Reactor Schemata.svg|right|thumb|Lead-Cooled Fast Reactor (LFR)]]
{{Main article|Lead-cooled fast reactor}}
{{See also|MYRRHA}}
The '''lead-cooled fast reactor'''<ref name="Roadmap">{{cite journal|year=2002 |title=A Technology Roadmap for Generation IV Nuclear Energy Systems |last=US DOE Nuclear Energy Research Advisory Committee |volume=GIF-002-00 |url=http://nuclear.energy.gov/genIV/documents/gen_iv_roadmap.pdf |deadurl=yes |archiveurl=https://web.archive.org/web/20071129121214/http://nuclear.energy.gov/genIV/documents/gen_iv_roadmap.pdf |archivedate=2007-11-29 |df= }}</ref> features a fast-neutron-spectrum [[lead]] or [[lead]]/[[bismuth]] [[eutectic]] ([[Lead-bismuth eutectic|LBE]]) liquid-metal-cooled reactor with a closed [[Nuclear fuel cycle|fuel cycle]]. Options include a range of plant ratings, including a "battery" of 50 to 150 MW of electricity that features a very long refueling interval, a modular system rated at 300 to 400 MW, and a large monolithic plant option at 1,200 MW (The term ''battery'' refers to the long-life, factory-fabricated core, not to any provision for electrochemical energy conversion). The fuel is metal or nitride-based containing [[Fertile material|fertile uranium]] and [[transuranic]]s. The LFR is cooled by natural [[convection]] with a reactor outlet coolant temperature of 550 °C, possibly ranging up to 800 °C with advanced materials. The higher temperature enables the production of [[Thermochemical cycle|hydrogen by thermochemical processes]].

The European Sustainable Nuclear Industrial Initiative is funding three Generation IV reactor systems, one of which is a lead-cooled fast reactor that is also an [[Subcritical reactor|accelerator-driven sub-critical]] reactor, called ''[[MYRRHA]]'', 100 MW(t), which will be built in [[Belgium]] with construction expected to begin after 2014 and the industrial scale version, known as ''Alfred'', slated to be constructed sometime after 2017. A reduced-power model of Myrrha called ''Guinevere'' was started up at [[Mol, Belgium|Mol]] in March 2009.<ref name="euronuclear.org"/> In 2012 the research team reported that Guinevere was operational.<ref>{{cite news|last1=Hellemans|first1=Alexander|title=Reactor-Accelerator Hybrid Achieves Successful Test Run|url=http://news.sciencemag.org/physics/2012/01/reactor-accelerator-hybrid-achieves-successful-test-run|accessdate=29 December 2014|work=Science Insider|date=12 January 2012}}</ref>

Two other lead-cooled fast reactors under development are the SVBR-100, a modular 100 MWe lead-bismuth cooled fast neutron reactor concept designed by OKB [[Gidropress]] in Russia and the [[BREST (Reactor)|BREST-OD-300]] (Lead-cooled fast reactor) 300 MWe, to be developed after the SVBR-100, and built over 2016-20, it will dispense with the [[Uranium-238|fertile blanket]] around the core and will supersede the sodium cooled [[BN-600 reactor]] design, to purportedly give enhanced proliferation resistance.<ref name="powertecrussia.com"/>

== Advantages and disadvantages ==
Relative to current nuclear power plant technology, the claimed benefits for 4th generation reactors include:
* Nuclear waste that remains radioactive for a few centuries instead of millennia<ref>{{cite web |title=Strategies to Address Global Warming |url=http://www.columbia.edu/~jeh1/mailings/2009/20090713_Strategies.pdf}}</ref>
* 100–300 times more energy yield from the same amount of nuclear fuel<ref>{{cite web |title=4th Generation Nuclear Power |url=http://www.ossfoundation.us/projects/energy/nuclear}}</ref>
* Broader range of fuels, and even unencapsulated raw fuels (non-pebble [[Molten Salt Reactor|MSR]], [[Liquid fluoride thorium reactor|LFTR]]).
* In some reactors, the ability to consume existing nuclear waste in the production of electricity, that is, a Closed [[nuclear fuel cycle]]. This strengthens the argument to deem [[nuclear power as renewable energy]].
* Improved operating safety features, such as (depending on design) avoidance of pressurized operation, automatic passive (unpowered, uncommanded) reactor shutdown, avoidance of water cooling and the associated risks of loss of water (leaks or boiling) and hydrogen generation/explosion and contamination of coolant water.

Nuclear reactors do not emit CO2 during operation, although like all [[low carbon power]] sources, the mining and construction phase can result in CO2 emissions, if energy sources which are not carbon neutral (such as fossil fuels), or CO2 emitting cements are used during the construction process.
A 2012 [[Yale University]] review published in the Journal of Industrial Ecology analyzing {{CO2}} [[life cycle assessment]] (LCA) emissions from [[nuclear power]] determined that:<ref name="Warner + Heath, JoIE">Warner, Ethan S.; Heath, Garvin A. [http://onlinelibrary.wiley.com/doi/10.1111/j.1530-9290.2012.00472.x/full Life Cycle Greenhouse Gas Emissions of Nuclear Electricity Generation: Systematic Review and Harmonization], ''Journal of Industrial Ecology'', [[Yale University]], published online April 17, 2012, {{doi|10.1111/j.1530-9290.2012.00472.x}}</ref>
{{Quote|The collective LCA literature indicates that life cycle [[Greenhouse gas|GHG]] [greenhouse gas] emissions from nuclear power are only a fraction of traditional fossil sources and comparable to renewable technologies.}}
Although the paper primarily dealt with data from [[Generation II reactor]]s, and did not analyze the {{CO2}} emissions by 2050 of the presently under construction [[Generation III reactor]]s, it did summarize the Life Cycle Assessment findings of in development reactor technologies.{{Quote|FBRs ['[[Fast Breeder Reactor]]s'] have been evaluated in the LCA literature. The limited literature that evaluates this potential future technology reports [[median]] life cycle GHG emissions... similar to or lower than LWRs [Gen II [[light water reactor]]s] and purports to consume little or no [[uranium market|uranium ore]].}}

A specific risk of the sodium-cooled fast reactor is related to using metallic sodium as a coolant. In case of a breach, sodium explosively reacts with water. Fixing breaches may also prove dangerous, as the cheapest noble gas [[argon]] is also used to prevent sodium oxidation. Argon, like helium, can displace oxygen in the air and can pose [[hypoxia (environmental)|hypoxia]] concerns, so workers may be exposed to this additional risk. This is a pertinent problem as demonstrated by the events at the [[LMFBR|loop type]] [[Monju Nuclear Power Plant|Prototype Fast Breeder Reactor Monju]] at Tsuruga, Japan.<ref>{{cite news |title=Japan Strains to Fix a Reactor Damaged Before Quake |url=https://www.nytimes.com/2011/06/18/world/asia/18japan.html | work=The New York Times | first=Hiroko |last=Tabuchi |date=17 June 2011}}</ref>
Using lead or molten salts mitigates this problem by making the coolant less reactive and allowing a high freezing temperature and low pressure in case of a leak. Disadvantages of lead compared to sodium are much higher viscosity, much higher density, lower heat capacity, and more radioactive neutron activation products.

In many cases, there is already a large amount of experience built up with numerous proof of concept Gen IV designs. For example, the reactors at [[Fort St. Vrain Generating Station]] and [[HTR-10]] are similar to the proposed Gen IV [[VHTR]] designs, and the [[LMFBR|pool type]] [[EBR-II]], [[Phénix]] and [[BN-600]] reactor are similar to the proposed pool type Gen IV Sodium Cooled Fast reactors being designed.

== Table of designs ==

{| class=wikitable
|+ Summary of designs for generation IV reactors<ref>https://www.gen-4.org/gif/upload/docs/application/pdf/2013-09/gif_rd_outlook_for_generation_iv_nuclear_energy_systems.pdf</ref>
|-
! System
! Neutron Spectrum
! Coolant
! Temperature (°C)
! Fuel Cycle
! Size (MW)
!Example developers
|-
| [[Very-high-temperature reactor|VHTR]]
| Thermal
| Helium
| 900–1000
| Open
| 250–300
|[[Japan Atomic Energy Agency|JAEA]] ([[High-temperature engineering test reactor|HTTR]]), [[Tsinghua University]] ([[HTR-10]]), [[X-energy]]<ref name="energy.gov">{{cite web|title=Energy Department Announces New Investments in Advanced Nuclear Power Reactors...|url=https://www.energy.gov/articles/energy-department-announces-new-investments-advanced-nuclear-power-reactors-help-meet|website=[[United States Department of Energy|US Department of Energy]]|accessdate=16 January 2016}}</ref>
|-
| [[Sodium-cooled fast reactor|SFR]]
| Fast
| Sodium
| 550
| Closed
| 30–150, 300–1500, 1000–2000
|[[TerraPower]] ([[Traveling wave reactor|TWR]]), [[Toshiba]] ([[Toshiba 4S|4S]]), [[GE Hitachi Nuclear Energy]] ([[PRISM (reactor)|PRISM]])
|-
| [[Supercritical water reactor|SCWR]]
| Thermal or fast
| Water
| 510–625
| Open or closed
| 300–700, 1000–1500
|
|-
| [[Gas-cooled fast reactor|GFR]]
| Fast
| Helium
| 850
| Closed
| 1200
|[[Energy Multiplier Module]]
|-
| [[Lead-cooled fast reactor|LFR]]
| Fast
| Lead
| 480–800
| Closed
| 20–180, 300–1200, 600–1000
|
|-
| [[Molten salt reactor|MSR]]
| Fast or thermal
| Fluoride or chloride salts
| 700–800
| Closed
| 250, 1000
|[[Seaborg Technologies]], [[TerraPower]], [[Stable Salt Reactor|Moltex Energy]], [[Flibe Energy]] ([[Liquid fluoride thorium reactor|LFTR]]), [[Transatomic Power]], Thorium Tech Solution ([[Fuji Molten Salt Reactor|FUJI MSR]]), Terrestrial Energy ([[IMSR]]), [[Southern Company Services|Southern Company]]<ref name="energy.gov"/>
|-
| [[Dual fluid reactor|DFR]]
| Fast
| Lead
| 1000
| Closed
| 500–1500
| Institute for Solid-State Nuclear Physics<ref name=ifk>{{cite web |url=https://festkoerper-kernphysik.de/dfr.pdf |title=Dual Fluid Reactor - IFK |date=2013-06-16 |website=festkoerper-kernphysik.de |publisher= Institut für Festkörper-Kernphysik |format=PDF |location=Berlin, Germany |access-date=2017-08-28}}</ref>
|}

== See also ==
{{portal|Energy|Nuclear technology}}
{{colbegin}}
* [[Nuclear reactor]]
* [[Nuclear material]]
* [[Nuclear physics]]
* [[List of reactor types#Reactor types|List of reactor types]]
* [[Generation II reactor]]
* [[Generation III reactor]]
* [[Integral Fast Reactor]]
* [[Liquid fluoride thorium reactor]]
* [[Breeder reactor]]
* [[Small modular reactor]]
{{colend}}

==References==
{{Reflist|30em}}

== External links ==
* [https://inlportal.inl.gov/portal/server.pt?open=514&objID=1361&parentname=CommunityPage&parentid=10&mode=2&in_hi_userid=200&cached=true Article from Idaho National Laboratory detailing some current efforts at developing Gen. IV reactors.]
* [http://www.gen-4.org/ Generation IV International Forum (GIF)]
* [https://web.archive.org/web/20070205115654/http://nuclear.energy.gov/genIV/neGenIV1.html U.S. Department of Energy Office of Nuclear Energy, Science and Technology]
* [https://web.archive.org/web/20060512033030/http://www.engr.utk.edu/nuclear/colloquia/slides/Gen%20IV%20U-Tenn%20Presentation.pdf Gen IV presentation]
* [http://www.ecology.at/ecology/files/pr577_1.pdf Science or Fiction - Is there a Future for Nuclear?] (Nov. 2007) - A publication from the Austrian [[Ecology Institute (Austria)|Ecology Institute]] about 'Generation IV' and Fusion reactors.
* {{cite web |url=http://memagazine.asme.org/Articles/2011/December/Nuclear_Power_After_Fukushima.cfm |title=Nuclear Power After Fukushima |author=Gail H. Marcus |date=December 2011 |work=Mechanical Engineering (the magazine of [[ASME]]) |accessdate=23 January 2012}} "In the wake of a severe plant accident, advanced reactor designs are getting renewed attention."
* [http://www.itheo.org/ International Thorium Energy Organisation - www.IThEO.org]
* [http://www.ithec.org/ International Thorium Energy Committee - iThEC]

{{Nuclear fission reactors}}

[[Category:Nuclear power reactor types]]
[[Category:Idaho National Laboratory]]

Benutzer:Snackroeg/Kernreaktoren der Generation 5

2018-04-30T21:26:42Z

Boundarylayer:

{{update|date=October 2017}}
[[File:GenIVRoadmap-en.svg|thumb|480px|Nuclear Energy Systems Deployable no later than 2030 and offering significant advances in sustainability, safety and reliability, and economics]]

'''Generation IV reactors''' ('''Gen IV''') are a set of [[nuclear reactor]] designs currently being researched for commercial applications by the Generation IV International Forum, with [[Technology readiness level]]s varying between the level requiring a demonstration, to economical competitive implementation.<ref>{{Cite journal|last=Locatelli|first=Giorgio|last2=Mancini|first2=Mauro|last3=Todeschini|first3=Nicola|date=2013-10-01|title=Generation IV nuclear reactors: Current status and future prospects|url=http://www.sciencedirect.com/science/article/pii/S0301421513006083|journal=Energy Policy|volume=61|pages=1503–1520|doi=10.1016/j.enpol.2013.06.101}}</ref> They are motivated by a variety of goals including improved safety, sustainability, efficiency, and cost.

The most developed Gen IV reactor design, the [[sodium fast reactor]], has received the greatest share of funding over the years, with the principle Gen IV aspect of the design, relating in largest part to the development of a sustainable closed [[Nuclear_fuel_cycle#Plutonium_cycle|fuel cycle]] for the reactor. Amongst nuclear engineers the [[molten-salt reactor]], the least developed and funded technology, is considered as potentially having the greatest [[inherent safety]] of the six models.<ref>[https://www.scientificamerican.com/article/can-sodium-save-nuclear-power/ Can Sodium Save Nuclear Power? Scientific American]</ref><ref>{{cite journal |last1=Moir |first1=Ralph |last2=Teller |first2=Edward |year=2005 |title=Thorium-Fueled Underground Power Plant Based on Molten Salt Technology |journal=Nuclear Technology |volume=151 |issue=3 |pages=334–340 |publisher=[[American Nuclear Society]] |url=http://www.new.ans.org/pubs/journals/nt/a_3655 |accessdate=March 22, 2012 }}</ref> While the [[hydrogen economy]], the use of hydrogen to produce [[Carbon-neutral fuel]]s, is deemed as strengthening the economic case for the two most efficient models, the [[Very-high-temperature reactor|high temperature reactor]] designs.<ref>[https://www.sciencedirect.com/science/article/pii/S0301421513006083 Generation IV nuclear reactors: Current status and future prospects doi.org/10.1016/j.enpol.2013.06.101]</ref>

The majority of the 6 designs are generally not expected to be available for commercial construction until 2020–30.<ref name="Generation IV">[http://www.world-nuclear.org/info/Nuclear-Fuel-Cycle/Power-Reactors/Generation-IV-Nuclear-Reactors/]</ref> Presently the majority of reactors in operation around the world are considered [[Generation II reactor|second generation reactor]] systems, as the vast majority of the [[Nuclear reactor#Classification by generation|first generation]] systems were retired some time ago, and there are only a dozen or so [[Generation III reactor]]s in operation as of 2014.
[[Nuclear reactor#Generation V+ reactors|Generation V reactors]] refer to reactors that are purely theoretical and are therefore not yet considered feasible in the short term, resulting in limited [[R&D]] funding.

== History ==
The Generation IV International Forum (GIF) is "a co-operative international endeavour which was set up to carry out the research and development needed to establish the feasibility and performance capabilities of the next generation nuclear energy systems."<ref>{{Cite web|url=https://www.gen-4.org/gif/jcms/c_9260/public|title=GIF Portal - Home - Public|website=www.gen-4.org|access-date=2016-07-25}}</ref> It was founded in 2001. Currently active members of the Generation IV International Forum (GIF) include: [[Australia]], [[Canada]], [[China]], the [[European Atomic Energy Community]] (Euratom), [[France]], [[Japan]], [[Russia]], [[South Africa]], [[South Korea]], [[Switzerland]], and the [[United States]]. The non-active members are [[Argentina]], [[Brazil]], and the [[United Kingdom]].<ref name="gen-4">{{cite web|url=https://www.gen-4.org/gif/jcms/c_9492/members|title=GIF Membership|website=gen-4.org|accessdate=28 October 2014}}</ref> Switzerland joined in 2002, Euratom in 2003, and China and Russia in 2006. The remaining countries (excluding Australia) were founding members.<ref name="gen-4" />

The 36th GIF meeting in [[Brussels]] was held in November 2013.<ref>{{cite web|url=https://www.energy.gov/ne/articles/generation-iv-international-forum-updates-technology-roadmap-and-builds-future|title=generation IV international forum updates technology roadmap and builds future. DOE}}</ref><ref>{{cite web|url=http://events.r20.constantcontact.com/register/event?llr=mscrkjkab&oeidk=a07e7melf609716b2c6 |title=The Generation IV international forum holds their 36th meeting on Monday 18th Nov 2013 in Brussels. }}{{dead link|date=January 2017 |bot=InternetArchiveBot |fix-attempted=yes }}</ref> The ''Technology Roadmap Update for Generation IV Nuclear Energy Systems'' was published in January 2014 which details R&D objectives for the next decade.<ref>[https://web.archive.org/web/20140625102915/https://www.gen-4.org/gif/upload/docs/application/pdf/2014-03/gif-tru2014.pdf Technology Roadmap Update for Generation IV Nuclear Energy Systems]</ref> A breakdown of the reactor designs being researched by each forum member has been made available.<ref>[https://web.archive.org/web/20140708023538/https://www.gen-4.org/gif/upload/docs/application/pdf/2014-03/gif_overview_presentation_v9_final3_web.pdf Generation IV International Forum, overview, John E. Kelly, page 15]</ref>

[[Nuclear power in Australia|Australia]] joined the forum in 2016.<ref>https://archive.is/20160907131656/https://www.gen-4.org/gif/jcms/c_71564/australia-joins-the-generation-iv-international-forum</ref>

In January 2018, it was reported that "the first installation of the pressure vessel cover of the world's first Gen IV reactor" had been completed on the [[HTR-PM]].<ref>http://www.world-nuclear-news.org/NN-First-HTR-PM-vessel-head-in-place-0401185.html</ref>

== Reactor types ==
Many reactor types were considered initially; however, the list was downsized to focus on the most promising technologies and those that could most likely meet the goals of the Gen IV initiative.<ref name="Generation IV"/> Three systems are nominally [[thermal reactor]]s and four are [[fast reactor]]s. The Very High Temperature Reactor (VHTR) is also being researched for potentially providing high quality process heat for [[thermochemical cycle|hydrogen production]]. The fast reactors offer the possibility of burning [[actinides]] to further reduce waste and of being able to "[[breeder reactor|breed more fuel]]" than they consume. These systems offer significant advances in sustainability, safety and reliability, economics, proliferation resistance (depending on perspective) and physical protection.

=== Thermal reactors ===
A [[Thermal-neutron reactor|thermal reactor]] is a [[nuclear reactor]] that uses slow or [[thermal neutrons]]. A [[neutron moderator]] is used to slow the [[neutron]]s emitted by fission to make them more likely to be captured by the fuel.

==== Very-high-temperature reactor (VHTR) ====
[[File:Very High Temperature Reactor.svg|right|thumb|Very-High-Temperature Reactor (VHTR)]]
{{Main article|Very high temperature reactor}}
{{see also|Fort St. Vrain Generating Station|High-temperature engineering test reactor|HTR-10}}
The '''very high temperature reactor''' concept uses a [[graphite]]-moderated core with a once-through [[uranium]] fuel cycle, using helium or molten salt as the [[Very high temperature reactor#Coolant|coolant]]. This reactor design envisions an outlet temperature of 1,000 °C. The reactor core can be either a prismatic-block or a [[pebble bed reactor]] design. The high temperatures enable applications such as process heat or [[hydrogen]] production via the thermochemical [[Sulfur-iodine cycle|iodine-sulfur]] process. It would also be [[Passive nuclear safety|passively safe]].

The planned construction of the first VHTR, the South African PBMR ([[pebble bed modular reactor]]), lost government funding in February, 2010.<ref>[http://www.powergenworldwide.com/index/display/articledisplay/6322207443/articles/power-engineering-international/volume-18/Issue_3/regulars/world-news/INTERNATIONAL.html South Africa to stop funding Pebble Bed nuclear reactor] {{webarchive|url=https://web.archive.org/web/20100909172743/http://www.powergenworldwide.com/index/display/articledisplay/6322207443/articles/power-engineering-international/volume-18/Issue_3/regulars/world-news/INTERNATIONAL.html |date=2010-09-09 }}</ref> A pronounced increase of costs and concerns about possible unexpected technical problems had discouraged potential investors and customers.

The [[Peoples Republic of China]] began construction of a 200-MW High Temperature Pebble bed reactor in 2012 as a successor to its [[HTR-10]].<ref>[http://www.nucnet.org/all-the-news/2013/01/07/china-begins-construction-of-first-generation-iv-htr-pm-unit Nucnet Report: 'China Begins Construction of First Generation IV HTR-PM Unit', 7 January 2013]</ref>

Also in 2012, as part of the [[Next Generation Nuclear Plant]] competition, [[Idaho National Laboratory]] approved a design similar to [[Areva]]'s prismatic block [http://us.areva.com/EN/home-3225/areva-inc-areva-htgr.html Antares reactor] as the chosen [[HTGR]] to be deployed as a prototype by 2021. It was in competition with [[General Atomics]]' [[Gas turbine modular helium reactor]] and [[Westinghouse Electric Company|Westinghouse]]'s [[Pebble Bed Modular Reactor]].<ref name="World nuclear news">{{cite web|url=http://www.world-nuclear-news.org/NN-Areva_modular_reactor_selected_for_NGNP_development-1502124.html|title=INL approves Antares design}}</ref>

[[X-energy]] was awarded a five-year $53M U.S. Department of Energy Advanced Reactor Concept Cooperative Agreement award to advance elements of their reactor development.<ref>[https://www.x-energy.com/doe-partnership]</ref>
The [[X-energy#Reactor Design|Xe-100]] is a pebble-bed modular reactor and will generate 200-MWt and approximately 76-MWe. The standard Xe-100 "four-pack" plant generates approximately 300-MWe and will fit on as few as 13 acres. All of the components for the Xe-100 will be road-transportable, and will be installed, rather than constructed, at the project site to streamline construction.<ref name="X-energy">{{cite web|url=https://www.x-energy.com/}}</ref>

==== Molten-salt reactor (MSR) ====
[[File:Molten Salt Reactor.svg|right|thumb|Molten Salt Reactor (MSR)]]
{{Main article|Molten salt reactor}}
{{see also|Liquid fluoride thorium reactor}}
A '''molten salt reactor'''<ref name="Roadmap"/> is a type of [[nuclear reactor]] where the primary [[coolant]], or even the fuel itself is a molten salt mixture. There have been many designs put forward for this type of reactor and a few prototypes built. The early concepts and many current ones rely on [[nuclear fuel]], perhaps [[uranium tetrafluoride]] (UF4) or [[thorium tetrafluoride]] (ThF4), dissolved in molten [[fluoride]] salt. The fluid would reach [[Nuclear reactor physics#Criticality|criticality]] by flowing into a core where [[graphite]] would serve as the [[neutron moderator|moderator]]. Many current concepts rely on fuel that is dispersed in a graphite matrix with the molten salt providing low pressure, high temperature cooling.

The Gen IV MSR is more accurately termed an [[epithermal neutron|epithermal reactor]] than a thermal reactor due to the average speed of the neutrons that would cause the fission events within its fuel being faster than [[thermal neutron]]s.<ref>{{cite web |url=https://inlportal.inl.gov/portal/server.pt?open=514&objID=1361&parentname=CommunityPage&parentid=10&mode=2&in_hi_userid=200&cached=true |title=Idaho National Laboratory detailing some current efforts at developing Gen. IV reactors}}</ref>

The principle of a MSR can be used for thermal, epithermal and fast reactors. Since 2005 the focus has moved towards a fast spectrum MSR (MSFR).<ref>H. Boussier, S. Delpech, V. Ghetta et Al. : The Molten Salt Reactor (MSR) in Generation IV: Overview and Perspectives, GIF SYMPOSIUM PROCEEDINGS/2012 ANNUAL REPORT, NEA No. 7141, pp95 [https://www.gen-4.org/gif/jcms/c_44720/annual-reports]
</ref>

While most MSR designs being pursued are largely derived from the 1960s [[Molten-Salt Reactor Experiment]] (MSRE), variants of molten salt technology include the conceptual ''[[Dual fluid reactor]]'' which is being designed with lead as a cooling medium but molten salt fuel, commonly as the metal chloride e.g. [[Plutonium(III) chloride]], to aid in greater "nuclear waste" closed-fuel cycle capabilities.
Other notable approaches differing substantially from MSRE include the ''[[Stable Salt Reactor]]''(SSR) concept promoted by MOLTEX, which encases the molten salt in hundreds of the common solid [[fuel rod]]s that are already well established in the nuclear industry. This latter British design was found to be the most competitive for [[Small modular reactor]] development by a British-based consultancy firm ''Energy Process Development'' in 2015.<ref>[http://www.daretothink.org/europe-moltex-stable-salt-reactor/ Europe: Moltex’ Stable Salt Reactor]</ref><ref>[http://analysis.nuclearenergyinsider.com/moltex-energy-sees-uk-canada-smr-licensing-springboard-asia Moltex Energy sees UK, Canada SMR licensing as springboard to Asia Jun 28, 2016]</ref>

Another notable feature of the MSR is the possibility of a [[Thermal-neutron reactor|thermal spectrum]] nuclear [[Nuclear fuel cycle#Fuel cycles|waste-burner]]. Conventionally only fast spectrum reactors have been considered viable for [[Nuclear fuel cycle#Minor actinides recycling|utilization or reduction]] of the [[Spent nuclear fuel|spent nuclear stockpiles]]. The conceptual viability of a thermal waste-burner was first shown in a whitepaper by [[Seaborg Technologies]] spring 2015.<ref name="Seaborg Whitepaper 2015">{{cite web|url=https://seaborg.dk/s/Seaborg-whitepaper-2015.pdf|title=Thermal MSR waste burner benchmark}}</ref> Thermal waste-burning was achieved by replacing a fraction of the [[uranium]] in the spent nuclear fuel with [[thorium]]. The net production rate of [[transuranium element]] (e.g. [[plutonium]] and [[americium]]) is reduced below the consumption rate, thus reducing the magnitude of the [[Radioactive waste|nuclear storage problem]]. Without the [[nuclear proliferation]] concerns and other [[Fast-neutron reactor#Disadvantages|technical issues]] associated with a [[Fast-neutron reactor|fast reactor]].

==== Supercritical-water-cooled reactor (SCWR) ====
[[File:Supercritical-Water-Cooled Reactor.svg|right|thumb|Supercritical-Water-Cooled Reactor (SCWR)]]
{{Main article|Supercritical water reactor}}
The '''supercritical water reactor''' (SCWR)<ref name="Roadmap"/> is a [[reduced moderation water reactor]] concept that, due to the average speed of the neutrons that would cause the fission events within the fuel being faster than [[thermal neutron]]s, it is more accurately termed an [[epithermal neutron|epithermal reactor]] than a thermal reactor. It uses [[supercritical fluid|supercritical water]] as the working fluid. SCWRs are basically [[light water reactor]]s (LWR) operating at higher pressure and temperatures with a direct, once-through heat exchange cycle. As most commonly envisioned, it would operate on a direct cycle, much like a boiling water reactor ([[BWR]]), but since it uses supercritical water (not to be confused with [[Critical mass (nuclear)|critical mass]]) as the working fluid, it would have only one water phase present, which makes the supercritical heat exchange method more similar to a pressurized water reactor ([[Pressurized water reactor|PWR]]). It could operate at much higher temperatures than both current PWRs and BWRs.

Supercritical water-cooled reactors (SCWRs) are promising advanced nuclear systems because of their high [[thermal efficiency]] (i.e., about 45% vs. about 33% efficiency for current LWRs) and considerable plant simplification.

The main mission of the SCWR is generation of low-cost [[electricity]]. It is built upon two proven technologies, LWRs, which are the most commonly deployed power generating reactors in the world, and superheated [[fossil fuel]] fired [[boiler]]s, a large number of which are also in use around the world. The SCWR concept is being investigated by 32 organizations in 13 countries.{{citation needed|date=October 2012}}

Because SCWRs are water reactors they share the steam explosion and radioactive steam release hazards of BWRs and LWRs as well as the need for extremely expensive heavy duty pressure vessels, pipes, valves, and pumps. These shared problems are inherently more severe for SCWRs due to operation at higher temperatures.

A SCWR Design under development is the [[VVER]]-1700/393 (VVER-SCWR or VVER-SKD) — a Russian Supercritical-water-cooled reactor with double-inlet-core and a [[breeder reactor|breeding ratio]] of 0.95.<ref name="powertecrussia.com">{{cite web |url=http://www.powertecrussia.com/blog/tag/nuclear-power/ |title=Technology Developments & Plant Efficiency for the Russian Nuclear Power Generation Market Wednesday |date=March 24, 2010}}</ref>

=== Fast reactors ===
A [[Fast-neutron reactor|fast reactor]] directly uses the fast neutrons emitted by fission, without moderation. Unlike thermal neutron reactors, fast neutron reactors can be configured to "'''burn'''", or fission, all [[actinides]], and given enough time, therefore drastically reduce the actinides fraction in [[spent nuclear fuel]] produced by the present world fleet of thermal neutron [[light water reactor]]s, thus closing the [[nuclear fuel cycle]]. Alternatively, if configured differently, they can also [[breeder reactor|'''breed''']] more actinide fuel than they consume.

==== Gas-cooled fast reactor (GFR) ====
[[File:Gas-Cooled Fast Reactor Schemata.svg|right|thumb|Gas-Cooled Fast Reactor (GFR)]]
{{Main article|Gas-cooled fast reactor}}
The '''gas-cooled fast reactor''' (GFR)<ref name="Roadmap"/> system features a fast-neutron spectrum and closed fuel cycle for efficient conversion of [[Fertile material|fertile uranium]] and management of actinides. The reactor is [[helium]]-cooled and with an outlet temperature of 850 °C it is an evolution of the [[very-high-temperature reactor]] (VHTR) to a more sustainable fuel cycle. It will use a direct [[Brayton cycle]] [[Closed-cycle gas turbine|gas turbine]] for high thermal efficiency. Several fuel forms are being considered for their potential to operate at very high temperatures and to ensure an excellent retention of [[Nuclear fission|fission]] products: composite [[ceramic]] fuel, advanced fuel particles, or ceramic clad elements of actinide compounds. Core configurations are being considered based on pin- or plate-based fuel assemblies or prismatic blocks.

The European Sustainable Nuclear Industrial Initiative is funding three Generation IV reactor systems, one of which is a gas-cooled fast reactor, called ''Allegro'', 100 MW(t), which will be built in a central or eastern European country with construction expected to begin in 2018.<ref name="euronuclear.org">{{cite web|url=https://www.euronuclear.org/1-information/news/Gen-IV.htm |title=The European Sustainable Nuclear Industrial Initiative (ESNII) will support three Generation IV reactor systems: a sodium-cooled fast reactor, or SFR, called ''Astrid'' that is proposed by France; a gas-cooled fast reactor, GFR, called ''Allegro'' supported by central and eastern Europe; and a lead-cooled fast reactor, LFR, technology pilot called ''Myrrha'' that is proposed by Belgium. |deadurl=yes |archiveurl=https://web.archive.org/web/20131009042600/http://euronuclear.org/1-information/news/Gen-IV.htm |archivedate=2013-10-09 |df= }}</ref> The central European [[Visegrád Group]] are committed to pursuing the technology.<ref>{{cite web |url=http://www.alphagalileo.org/ViewItem.aspx?ItemId=133111&CultureCode=en |title=The V4G4 Centre of Excellence for performing joint research, development and innovation in the field of Generation-4 (G4) nuclear reactors have been established. 20 July 2013 National Center for Nuclear Research (NCBJ)}}</ref> In 2013 German, British, and French institutes finished a 3-year collaboration study on the follow on industrial scale design, known as ''GoFastR''.<ref>{{cite web|url=http://www.ist-world.org/ProjectDetails.aspx?ProjectId=5cb8f3f283574cc6b2bdbf72533172d8 |title=the European Gas cooled Fast Reactor. |deadurl=yes |archiveurl=https://web.archive.org/web/20131213091046/http://www.ist-world.org/ProjectDetails.aspx?ProjectId=5cb8f3f283574cc6b2bdbf72533172d8 |archivedate=2013-12-13 |df= }}</ref> They were funded by the EU's 7th FWP [[framework programme]], with the goal of making a sustainable VHTR.<ref>{{cite web |url=http://www.2020-horizon.com/GOFASTR-European-Gas-Cooled-Fast-Reactor%28GOFASTR%29-s312.html |title=The GOFASTR research program}}</ref>

==== Sodium-cooled fast reactor (SFR) ====
[[File:Sodium-Cooled Fast Reactor Schemata.svg|right|thumb|Pool design Sodium-Cooled Fast Reactor (SFR)]]
{{Main article|Sodium-cooled fast reactor}}
{{see also|Prototype Fast Breeder Reactor|Experimental Breeder Reactor II|S-PRISM|BN-800 reactor|Toshiba 4S|CFR-600}}

In India, the [[Fast Breeder Test Reactor]] reached criticality in October 1985. In September 2002, fuel burn-up in the FBTR for the first time reached the 100,000 megawatt-days per metric ton uranium (MWd/MTU) mark. This is considered an important milestone in breeder reactor technology. Using the experience gained from the operation of the FBTR, the [[Prototype Fast Breeder Reactor]], a 500 MWe Sodium cooled fast reactor is being built at a cost of INR 5,677 crores (~US$900 million) and is expected to be critical by June 2018. The PFBR will be followed by six more Commercial Fast Breeder Reactors (CFBRs) of 600 MWe each.

The SFR<ref name="Roadmap"/> is a project that builds on two closely related existing projects, the liquid metal [[Breeder reactor#Fast breeder reactor|fast breeder reactor]] and the [[integral fast reactor]].

The goals are to increase the efficiency of uranium usage by [[breeder reactor|breeding]] plutonium and eliminating the need for [[transuranic]] isotopes ever to leave the site. The reactor design uses an unmoderated core running on [[fast neutron]]s, designed to allow any transuranic isotope to be consumed (and in some cases used as fuel). In addition to the benefits of removing the long [[half-life]] transuranics from the waste cycle, the SFR fuel expands when the reactor overheats, and the chain reaction automatically slows down. In this manner, it is passively safe.<ref>{{cite web |url=http://www.ne.anl.gov/About/hn/logos-winter02-psr.shtml|title=Passively safe reactors rely on nature to keep them cool|author=David Baurac}}</ref>

The SFR reactor concept is cooled by liquid [[sodium]] and fueled by a metallic alloy of uranium and [[plutonium]] or [[spent nuclear fuel]], the "nuclear waste" of [[light water reactor]]s. The SFR fuel is contained in steel cladding with liquid sodium filling in the space between the clad elements which make up the fuel assembly. One of the design challenges of an SFR is the risks of handling sodium, which reacts explosively if it comes into contact with water. However, the use of liquid metal instead of water as coolant allows the system to work at atmospheric pressure, reducing the risk of leakage.

[[File:Ifr concept.jpg|thumb|375px|The sustainable fuel-cycle proposed in the 1990s [[Integral fast reactor]] concept (color), an animation of the [[pyroprocessing]] technology is also available.<ref>{{cite web |url=https://www.youtube.com/watch?v=cBThTwFhRlA |title=Historical video about the Integral Fast Reactor (IFR) concept. Uploaded by - Nuclear Engineering at Argonne}}</ref>]]
[[File:IFR concept.png|thumb|375px|IFR concept (Black and White with clearer text)]]

The European Sustainable Nuclear Industrial Initiative is funding three Generation IV reactor systems, one of which is a sodium-cooled fast reactor, called ''[[ASTRID (reactor)|ASTRID]]'', Advanced Sodium Technical Reactor for Industrial Demonstration, [[Areva]], [[Commissariat à l'énergie atomique et aux énergies alternatives|CEA]] and [[Électricité de France|EDF]] are leading the design with British collaboration.<ref>{{cite web |url=http://www.power-eng.com/articles/2010/11/areva--cea-secure.html |title=Areva, CEA secure EUR650m funding to develop ASTRID sodium-cooled Generation IV reactor 11/11/2010}}</ref><ref>{{cite web |url=http://www.powermag.com/uk-and-france-sign-landmark-civil-nuclear-cooperation-agreement/ |title=UK and France Sign Landmark Civil Nuclear Cooperation Agreement 02/22/2012 . POWERnews}}</ref> Astrid will be rated about 600 MWe and is proposed to be built in France, near to the [[Phénix]] reactor. A final decision in construction is to be made in 2019<ref name="euronuclear.org"/>

The [[China|PRC]]'s first commercial-scale, 800 MWe, fast neutron reactor, to be situated near [[Sanming]] in [[Fujian province]] will be a SFR. In 2009 an agreement was signed that would entail the Russian [[BN-800 reactor]] design to be sold to the PRC once it is completed, this would be the first time commercial-scale fast neutron reactors have ever been exported.<ref>{{cite web |url=http://www.world-nuclear-news.org/C-Joint_venture_launched_for_Chinese_fast_reactor-3004104.html |title=Joint venture launched for Chinese fast reactor}}</ref> The BN-800 reactor became operational in 2014.

The 400 MWe [[Fast Flux Test Facility]] operated successfully for ten years at the Hanford site in Washington State.

The 20 MWe [[EBR II]] operated successfully for over thirty years at the Idaho National Laboratory, until it was shut down in 1994.

GE Hitachi's [[PRISM (reactor)|PRISM]] reactor is a modernized and commercial implementation of the technology developed for the Integral Fast Reactor(IFR), developed by [[Argonne National Laboratory]] between 1984 and 1994. With the primary purpose of PRISM differing in the focus on burning up [[spent nuclear fuel]] from other reactors, rather than [[breeder reactor|breeding]] new fuel. Presented as an alternative to burying the spent fuel/waste. The design reduces the half lives of the fissionable elements present in spent nuclear fuel while generating electricity largely as a by-product.

==== Lead-cooled fast reactor (LFR) ====
[[File:Lead-Cooled Fast Reactor Schemata.svg|right|thumb|Lead-Cooled Fast Reactor (LFR)]]
{{Main article|Lead-cooled fast reactor}}
{{See also|MYRRHA}}
The '''lead-cooled fast reactor'''<ref name="Roadmap">{{cite journal|year=2002 |title=A Technology Roadmap for Generation IV Nuclear Energy Systems |last=US DOE Nuclear Energy Research Advisory Committee |volume=GIF-002-00 |url=http://nuclear.energy.gov/genIV/documents/gen_iv_roadmap.pdf |deadurl=yes |archiveurl=https://web.archive.org/web/20071129121214/http://nuclear.energy.gov/genIV/documents/gen_iv_roadmap.pdf |archivedate=2007-11-29 |df= }}</ref> features a fast-neutron-spectrum [[lead]] or [[lead]]/[[bismuth]] [[eutectic]] ([[Lead-bismuth eutectic|LBE]]) liquid-metal-cooled reactor with a closed [[Nuclear fuel cycle|fuel cycle]]. Options include a range of plant ratings, including a "battery" of 50 to 150 MW of electricity that features a very long refueling interval, a modular system rated at 300 to 400 MW, and a large monolithic plant option at 1,200 MW (The term ''battery'' refers to the long-life, factory-fabricated core, not to any provision for electrochemical energy conversion). The fuel is metal or nitride-based containing [[Fertile material|fertile uranium]] and [[transuranic]]s. The LFR is cooled by natural [[convection]] with a reactor outlet coolant temperature of 550 °C, possibly ranging up to 800 °C with advanced materials. The higher temperature enables the production of [[Thermochemical cycle|hydrogen by thermochemical processes]].

The European Sustainable Nuclear Industrial Initiative is funding three Generation IV reactor systems, one of which is a lead-cooled fast reactor that is also an [[Subcritical reactor|accelerator-driven sub-critical]] reactor, called ''[[MYRRHA]]'', 100 MW(t), which will be built in [[Belgium]] with construction expected to begin after 2014 and the industrial scale version, known as ''Alfred'', slated to be constructed sometime after 2017. A reduced-power model of Myrrha called ''Guinevere'' was started up at [[Mol, Belgium|Mol]] in March 2009.<ref name="euronuclear.org"/> In 2012 the research team reported that Guinevere was operational.<ref>{{cite news|last1=Hellemans|first1=Alexander|title=Reactor-Accelerator Hybrid Achieves Successful Test Run|url=http://news.sciencemag.org/physics/2012/01/reactor-accelerator-hybrid-achieves-successful-test-run|accessdate=29 December 2014|work=Science Insider|date=12 January 2012}}</ref>

Two other lead-cooled fast reactors under development are the SVBR-100, a modular 100 MWe lead-bismuth cooled fast neutron reactor concept designed by OKB [[Gidropress]] in Russia and the [[BREST (Reactor)|BREST-OD-300]] (Lead-cooled fast reactor) 300 MWe, to be developed after the SVBR-100, and built over 2016-20, it will dispense with the [[Uranium-238|fertile blanket]] around the core and will supersede the sodium cooled [[BN-600 reactor]] design, to purportedly give enhanced proliferation resistance.<ref name="powertecrussia.com"/>

== Advantages and disadvantages ==
Relative to current nuclear power plant technology, the claimed benefits for 4th generation reactors include:
* Nuclear waste that remains radioactive for a few centuries instead of millennia<ref>{{cite web |title=Strategies to Address Global Warming |url=http://www.columbia.edu/~jeh1/mailings/2009/20090713_Strategies.pdf}}</ref>
* 100–300 times more energy yield from the same amount of nuclear fuel<ref>{{cite web |title=4th Generation Nuclear Power |url=http://www.ossfoundation.us/projects/energy/nuclear}}</ref>
* Broader range of fuels, and even unencapsulated raw fuels (non-pebble [[Molten Salt Reactor|MSR]], [[Liquid fluoride thorium reactor|LFTR]]).
* In some reactors, the ability to consume existing nuclear waste in the production of electricity, that is, a Closed [[nuclear fuel cycle]]. This strengthens the argument to deem [[nuclear power as renewable energy]].
* Improved operating safety features, such as (depending on design) avoidance of pressurized operation, automatic passive (unpowered, uncommanded) reactor shutdown, avoidance of water cooling and the associated risks of loss of water (leaks or boiling) and hydrogen generation/explosion and contamination of coolant water.

Nuclear reactors do not emit CO2 during operation, although like all [[low carbon power]] sources, the mining and construction phase can result in CO2 emissions, if energy sources which are not carbon neutral (such as fossil fuels), or CO2 emitting cements are used during the construction process.
A 2012 [[Yale University]] review published in the Journal of Industrial Ecology analyzing {{CO2}} [[life cycle assessment]] (LCA) emissions from [[nuclear power]] determined that:<ref name="Warner + Heath, JoIE">Warner, Ethan S.; Heath, Garvin A. [http://onlinelibrary.wiley.com/doi/10.1111/j.1530-9290.2012.00472.x/full Life Cycle Greenhouse Gas Emissions of Nuclear Electricity Generation: Systematic Review and Harmonization], ''Journal of Industrial Ecology'', [[Yale University]], published online April 17, 2012, {{doi|10.1111/j.1530-9290.2012.00472.x}}</ref>
{{Quote|The collective LCA literature indicates that life cycle [[Greenhouse gas|GHG]] [greenhouse gas] emissions from nuclear power are only a fraction of traditional fossil sources and comparable to renewable technologies.}}
Although the paper primarily dealt with data from [[Generation II reactor]]s, and did not analyze the {{CO2}} emissions by 2050 of the presently under construction [[Generation III reactor]]s, it did summarize the Life Cycle Assessment findings of in development reactor technologies.{{Quote|FBRs ['[[Fast Breeder Reactor]]s'] have been evaluated in the LCA literature. The limited literature that evaluates this potential future technology reports [[median]] life cycle GHG emissions... similar to or lower than LWRs [Gen II [[light water reactor]]s] and purports to consume little or no [[uranium market|uranium ore]].}}

A specific risk of the sodium-cooled fast reactor is related to using metallic sodium as a coolant. In case of a breach, sodium explosively reacts with water. Fixing breaches may also prove dangerous, as the cheapest noble gas [[argon]] is also used to prevent sodium oxidation. Argon, like helium, can displace oxygen in the air and can pose [[hypoxia (environmental)|hypoxia]] concerns, so workers may be exposed to this additional risk. This is a pertinent problem as demonstrated by the events at the [[LMFBR|loop type]] [[Monju Nuclear Power Plant|Prototype Fast Breeder Reactor Monju]] at Tsuruga, Japan.<ref>{{cite news |title=Japan Strains to Fix a Reactor Damaged Before Quake |url=https://www.nytimes.com/2011/06/18/world/asia/18japan.html | work=The New York Times | first=Hiroko |last=Tabuchi |date=17 June 2011}}</ref>
Using lead or molten salts mitigates this problem by making the coolant less reactive and allowing a high freezing temperature and low pressure in case of a leak. Disadvantages of lead compared to sodium are much higher viscosity, much higher density, lower heat capacity, and more radioactive neutron activation products.

In many cases, there is already a large amount of experience built up with numerous proof of concept Gen IV designs. For example, the reactors at [[Fort St. Vrain Generating Station]] and [[HTR-10]] are similar to the proposed Gen IV [[VHTR]] designs, and the [[LMFBR|pool type]] [[EBR-II]], [[Phénix]] and [[BN-600]] reactor are similar to the proposed pool type Gen IV Sodium Cooled Fast reactors being designed.

== Table of designs ==

{| class=wikitable
|+ Summary of designs for generation IV reactors<ref>https://www.gen-4.org/gif/upload/docs/application/pdf/2013-09/gif_rd_outlook_for_generation_iv_nuclear_energy_systems.pdf</ref>
|-
! System
! Neutron Spectrum
! Coolant
! Temperature (°C)
! Fuel Cycle
! Size (MW)
!Example developers
|-
| [[Very-high-temperature reactor|VHTR]]
| Thermal
| Helium
| 900–1000
| Open
| 250–300
|[[Japan Atomic Energy Agency|JAEA]] ([[High-temperature engineering test reactor|HTTR]]), [[Tsinghua University]] ([[HTR-10]]), [[X-energy]]<ref name="energy.gov">{{cite web|title=Energy Department Announces New Investments in Advanced Nuclear Power Reactors...|url=https://www.energy.gov/articles/energy-department-announces-new-investments-advanced-nuclear-power-reactors-help-meet|website=[[United States Department of Energy|US Department of Energy]]|accessdate=16 January 2016}}</ref>
|-
| [[Sodium-cooled fast reactor|SFR]]
| Fast
| Sodium
| 550
| Closed
| 30–150, 300–1500, 1000–2000
|[[TerraPower]] ([[Traveling wave reactor|TWR]]), [[Toshiba]] ([[Toshiba 4S|4S]]), [[GE Hitachi Nuclear Energy]] ([[PRISM (reactor)|PRISM]])
|-
| [[Supercritical water reactor|SCWR]]
| Thermal or fast
| Water
| 510–625
| Open or closed
| 300–700, 1000–1500
|
|-
| [[Gas-cooled fast reactor|GFR]]
| Fast
| Helium
| 850
| Closed
| 1200
|[[Energy Multiplier Module]]
|-
| [[Lead-cooled fast reactor|LFR]]
| Fast
| Lead
| 480–800
| Closed
| 20–180, 300–1200, 600–1000
|
|-
| [[Molten salt reactor|MSR]]
| Fast or thermal
| Fluoride or chloride salts
| 700–800
| Closed
| 250, 1000
|[[Seaborg Technologies]], [[TerraPower]], [[Stable Salt Reactor|Moltex Energy]], [[Flibe Energy]] ([[Liquid fluoride thorium reactor|LFTR]]), [[Transatomic Power]], Thorium Tech Solution ([[Fuji Molten Salt Reactor|FUJI MSR]]), Terrestrial Energy ([[IMSR]]), [[Southern Company Services|Southern Company]]<ref name="energy.gov"/>
|-
| [[Dual fluid reactor|DFR]]
| Fast
| Lead
| 1000
| Closed
| 500–1500
| Institute for Solid-State Nuclear Physics<ref name=ifk>{{cite web |url=https://festkoerper-kernphysik.de/dfr.pdf |title=Dual Fluid Reactor - IFK |date=2013-06-16 |website=festkoerper-kernphysik.de |publisher= Institut für Festkörper-Kernphysik |format=PDF |location=Berlin, Germany |access-date=2017-08-28}}</ref>
|}

== See also ==
{{portal|Energy|Nuclear technology}}
{{colbegin}}
* [[Nuclear reactor]]
* [[Nuclear material]]
* [[Nuclear physics]]
* [[List of reactor types#Reactor types|List of reactor types]]
* [[Generation II reactor]]
* [[Generation III reactor]]
* [[Integral Fast Reactor]]
* [[Liquid fluoride thorium reactor]]
* [[Breeder reactor]]
* [[Small modular reactor]]
{{colend}}

==References==
{{Reflist|30em}}

== External links ==
* [https://inlportal.inl.gov/portal/server.pt?open=514&objID=1361&parentname=CommunityPage&parentid=10&mode=2&in_hi_userid=200&cached=true Article from Idaho National Laboratory detailing some current efforts at developing Gen. IV reactors.]
* [http://www.gen-4.org/ Generation IV International Forum (GIF)]
* [https://web.archive.org/web/20070205115654/http://nuclear.energy.gov/genIV/neGenIV1.html U.S. Department of Energy Office of Nuclear Energy, Science and Technology]
* [https://web.archive.org/web/20060512033030/http://www.engr.utk.edu/nuclear/colloquia/slides/Gen%20IV%20U-Tenn%20Presentation.pdf Gen IV presentation]
* [http://www.ecology.at/ecology/files/pr577_1.pdf Science or Fiction - Is there a Future for Nuclear?] (Nov. 2007) - A publication from the Austrian [[Ecology Institute (Austria)|Ecology Institute]] about 'Generation IV' and Fusion reactors.
* {{cite web |url=http://memagazine.asme.org/Articles/2011/December/Nuclear_Power_After_Fukushima.cfm |title=Nuclear Power After Fukushima |author=Gail H. Marcus |date=December 2011 |work=Mechanical Engineering (the magazine of [[ASME]]) |accessdate=23 January 2012}} "In the wake of a severe plant accident, advanced reactor designs are getting renewed attention."
* [http://www.itheo.org/ International Thorium Energy Organisation - www.IThEO.org]
* [http://www.ithec.org/ International Thorium Energy Committee - iThEC]

{{Nuclear fission reactors}}

[[Category:Nuclear power reactor types]]
[[Category:Idaho National Laboratory]]

Benutzer:Snackroeg/Kernreaktoren der Generation 5

2018-04-18T14:55:39Z

Boundarylayer: /* Sodium-cooled fast reactor (SFR) */

{{update|date=October 2017}}
[[File:GenIVRoadmap-en.svg|thumb|480px|Nuclear Energy Systems Deployable no later than 2030 and offering significant advances in sustainability, safety and reliability, and economics]]

'''Generation IV reactors''' ('''Gen IV''') are a set of [[nuclear reactor]] designs currently being researched for commercial applications by the Generation IV International Forum, with [[Technology readiness level]]s varying between the level requiring a demonstration, to economical competitive implementation.<ref>{{Cite journal|last=Locatelli|first=Giorgio|last2=Mancini|first2=Mauro|last3=Todeschini|first3=Nicola|date=2013-10-01|title=Generation IV nuclear reactors: Current status and future prospects|url=http://www.sciencedirect.com/science/article/pii/S0301421513006083|journal=Energy Policy|volume=61|pages=1503–1520|doi=10.1016/j.enpol.2013.06.101}}</ref> They are motivated by a variety of goals including improved safety, sustainability, efficiency, and cost.

The most developed Gen IV reactor design, the [[sodium fast reactor]], has received the greatest share of funding over the years, with the principle Gen IV aspect of the design, relating in largest part to the development of a sustainable closed [[nuclear fuel cycle|fuel cycle]] for the reactor. Amongst nuclear engineers the [[molten-salt reactor]], the least developed and funded technology, is considered as potentially having the greatest [[inherent safety]] of the six models.<ref>[https://www.scientificamerican.com/article/can-sodium-save-nuclear-power/ Can Sodium Save Nuclear Power? Scientific American]</ref><ref>{{cite journal |last1=Moir |first1=Ralph |last2=Teller |first2=Edward |year=2005 |title=Thorium-Fueled Underground Power Plant Based on Molten Salt Technology |journal=Nuclear Technology |volume=151 |issue=3 |pages=334–340 |publisher=[[American Nuclear Society]] |url=http://www.new.ans.org/pubs/journals/nt/a_3655 |accessdate=March 22, 2012 }}</ref> While the [[hydrogen economy]], the use of hydrogen to produce [[Carbon-neutral fuel]]s, is deemed as strengthening the economic case for the two most efficient models, the [[Very-high-temperature reactor|high temperature reactor]] designs.<ref>[https://www.sciencedirect.com/science/article/pii/S0301421513006083 Generation IV nuclear reactors: Current status and future prospects doi.org/10.1016/j.enpol.2013.06.101]</ref>

The majority of the 6 designs are generally not expected to be available for commercial construction until 2020–30.<ref name="Generation IV">[http://www.world-nuclear.org/info/Nuclear-Fuel-Cycle/Power-Reactors/Generation-IV-Nuclear-Reactors/]</ref> Presently the majority of reactors in operation around the world are considered [[Generation II reactor|second generation reactor]] systems, as the vast majority of the [[Nuclear reactor#Classification by generation|first generation]] systems were retired some time ago, and there are only a dozen or so [[Generation III reactor]]s in operation as of 2014.
[[Nuclear reactor#Generation V+ reactors|Generation V reactors]] refer to reactors that are purely theoretical and are therefore not yet considered feasible in the short term, resulting in limited [[R&D]] funding.

== History ==
The Generation IV International Forum (GIF) is "a co-operative international endeavour which was set up to carry out the research and development needed to establish the feasibility and performance capabilities of the next generation nuclear energy systems."<ref>{{Cite web|url=https://www.gen-4.org/gif/jcms/c_9260/public|title=GIF Portal - Home - Public|website=www.gen-4.org|access-date=2016-07-25}}</ref> It was founded in 2001. Currently active members of the Generation IV International Forum (GIF) include: [[Australia]], [[Canada]], [[China]], the [[European Atomic Energy Community]] (Euratom), [[France]], [[Japan]], [[Russia]], [[South Africa]], [[South Korea]], [[Switzerland]], and the [[United States]]. The non-active members are [[Argentina]], [[Brazil]], and the [[United Kingdom]].<ref name="gen-4">{{cite web|url=https://www.gen-4.org/gif/jcms/c_9492/members|title=GIF Membership|website=gen-4.org|accessdate=28 October 2014}}</ref> Switzerland joined in 2002, Euratom in 2003, and China and Russia in 2006. The remaining countries (excluding Australia) were founding members.<ref name="gen-4" />

The 36th GIF meeting in [[Brussels]] was held in November 2013.<ref>{{cite web|url=https://www.energy.gov/ne/articles/generation-iv-international-forum-updates-technology-roadmap-and-builds-future|title=generation IV international forum updates technology roadmap and builds future. DOE}}</ref><ref>{{cite web|url=http://events.r20.constantcontact.com/register/event?llr=mscrkjkab&oeidk=a07e7melf609716b2c6 |title=The Generation IV international forum holds their 36th meeting on Monday 18th Nov 2013 in Brussels. }}{{dead link|date=January 2017 |bot=InternetArchiveBot |fix-attempted=yes }}</ref> The ''Technology Roadmap Update for Generation IV Nuclear Energy Systems'' was published in January 2014 which details R&D objectives for the next decade.<ref>[https://web.archive.org/web/20140625102915/https://www.gen-4.org/gif/upload/docs/application/pdf/2014-03/gif-tru2014.pdf Technology Roadmap Update for Generation IV Nuclear Energy Systems]</ref> A breakdown of the reactor designs being researched by each forum member has been made available.<ref>[https://web.archive.org/web/20140708023538/https://www.gen-4.org/gif/upload/docs/application/pdf/2014-03/gif_overview_presentation_v9_final3_web.pdf Generation IV International Forum, overview, John E. Kelly, page 15]</ref>

[[Nuclear power in Australia|Australia]] joined the forum in 2016.<ref>https://archive.is/20160907131656/https://www.gen-4.org/gif/jcms/c_71564/australia-joins-the-generation-iv-international-forum</ref>

In January 2018, it was reported that "the first installation of the pressure vessel cover of the world's first Gen IV reactor" had been completed on the [[HTR-PM]].<ref>http://www.world-nuclear-news.org/NN-First-HTR-PM-vessel-head-in-place-0401185.html</ref>

== Reactor types ==
Many reactor types were considered initially; however, the list was downsized to focus on the most promising technologies and those that could most likely meet the goals of the Gen IV initiative.<ref name="Generation IV"/> Three systems are nominally [[thermal reactor]]s and four are [[fast reactor]]s. The Very High Temperature Reactor (VHTR) is also being researched for potentially providing high quality process heat for [[thermochemical cycle|hydrogen production]]. The fast reactors offer the possibility of burning [[actinides]] to further reduce waste and of being able to "[[breeder reactor|breed more fuel]]" than they consume. These systems offer significant advances in sustainability, safety and reliability, economics, proliferation resistance (depending on perspective) and physical protection.

=== Thermal reactors ===
A [[Thermal-neutron reactor|thermal reactor]] is a [[nuclear reactor]] that uses slow or [[thermal neutrons]]. A [[neutron moderator]] is used to slow the [[neutron]]s emitted by fission to make them more likely to be captured by the fuel.

==== Very-high-temperature reactor (VHTR) ====
[[File:Very High Temperature Reactor.svg|right|thumb|Very-High-Temperature Reactor (VHTR)]]
{{Main article|Very high temperature reactor}}
{{see also|Fort St. Vrain Generating Station|High-temperature engineering test reactor|HTR-10}}
The '''very high temperature reactor''' concept uses a [[graphite]]-moderated core with a once-through [[uranium]] fuel cycle, using helium or molten salt as the [[Very high temperature reactor#Coolant|coolant]]. This reactor design envisions an outlet temperature of 1,000 °C. The reactor core can be either a prismatic-block or a [[pebble bed reactor]] design. The high temperatures enable applications such as process heat or [[hydrogen]] production via the thermochemical [[Sulfur-iodine cycle|iodine-sulfur]] process. It would also be [[Passive nuclear safety|passively safe]].

The planned construction of the first VHTR, the South African PBMR ([[pebble bed modular reactor]]), lost government funding in February, 2010.<ref>[http://www.powergenworldwide.com/index/display/articledisplay/6322207443/articles/power-engineering-international/volume-18/Issue_3/regulars/world-news/INTERNATIONAL.html South Africa to stop funding Pebble Bed nuclear reactor] {{webarchive|url=https://web.archive.org/web/20100909172743/http://www.powergenworldwide.com/index/display/articledisplay/6322207443/articles/power-engineering-international/volume-18/Issue_3/regulars/world-news/INTERNATIONAL.html |date=2010-09-09 }}</ref> A pronounced increase of costs and concerns about possible unexpected technical problems had discouraged potential investors and customers.

The [[Peoples Republic of China]] began construction of a 200-MW High Temperature Pebble bed reactor in 2012 as a successor to its [[HTR-10]].<ref>[http://www.nucnet.org/all-the-news/2013/01/07/china-begins-construction-of-first-generation-iv-htr-pm-unit Nucnet Report: 'China Begins Construction of First Generation IV HTR-PM Unit', 7 January 2013]</ref>

Also in 2012, as part of the [[Next Generation Nuclear Plant]] competition, [[Idaho National Laboratory]] approved a design similar to [[Areva]]'s prismatic block [http://us.areva.com/EN/home-3225/areva-inc-areva-htgr.html Antares reactor] as the chosen [[HTGR]] to be deployed as a prototype by 2021. It was in competition with [[General Atomics]]' [[Gas turbine modular helium reactor]] and [[Westinghouse Electric Company|Westinghouse]]'s [[Pebble Bed Modular Reactor]].<ref name="World nuclear news">{{cite web|url=http://www.world-nuclear-news.org/NN-Areva_modular_reactor_selected_for_NGNP_development-1502124.html|title=INL approves Antares design}}</ref>

[[X-energy]] was awarded a five-year $53M U.S. Department of Energy Advanced Reactor Concept Cooperative Agreement award to advance elements of their reactor development.<ref>[https://www.x-energy.com/doe-partnership]</ref>
The [[X-energy#Reactor Design|Xe-100]] is a pebble-bed modular reactor and will generate 200-MWt and approximately 76-MWe. The standard Xe-100 "four-pack" plant generates approximately 300-MWe and will fit on as few as 13 acres. All of the components for the Xe-100 will be road-transportable, and will be installed, rather than constructed, at the project site to streamline construction.<ref name="X-energy">{{cite web|url=https://www.x-energy.com/}}</ref>

==== Molten-salt reactor (MSR) ====
[[File:Molten Salt Reactor.svg|right|thumb|Molten Salt Reactor (MSR)]]
{{Main article|Molten salt reactor}}
{{see also|Liquid fluoride thorium reactor}}
A '''molten salt reactor'''<ref name="Roadmap"/> is a type of [[nuclear reactor]] where the primary [[coolant]], or even the fuel itself is a molten salt mixture. There have been many designs put forward for this type of reactor and a few prototypes built. The early concepts and many current ones rely on [[nuclear fuel]], perhaps [[uranium tetrafluoride]] (UF4) or [[thorium tetrafluoride]] (ThF4), dissolved in molten [[fluoride]] salt. The fluid would reach [[Nuclear reactor physics#Criticality|criticality]] by flowing into a core where [[graphite]] would serve as the [[neutron moderator|moderator]]. Many current concepts rely on fuel that is dispersed in a graphite matrix with the molten salt providing low pressure, high temperature cooling.

The Gen IV MSR is more accurately termed an [[epithermal neutron|epithermal reactor]] than a thermal reactor due to the average speed of the neutrons that would cause the fission events within its fuel being faster than [[thermal neutron]]s.<ref>{{cite web |url=https://inlportal.inl.gov/portal/server.pt?open=514&objID=1361&parentname=CommunityPage&parentid=10&mode=2&in_hi_userid=200&cached=true |title=Idaho National Laboratory detailing some current efforts at developing Gen. IV reactors}}</ref>

The principle of a MSR can be used for thermal, epithermal and fast reactors. Since 2005 the focus has moved towards a fast spectrum MSR (MSFR).<ref>H. Boussier, S. Delpech, V. Ghetta et Al. : The Molten Salt Reactor (MSR) in Generation IV: Overview and Perspectives, GIF SYMPOSIUM PROCEEDINGS/2012 ANNUAL REPORT, NEA No. 7141, pp95 [https://www.gen-4.org/gif/jcms/c_44720/annual-reports]
</ref>

While most MSR designs being pursued are largely derived from the 1960s [[Molten-Salt Reactor Experiment]] (MSRE), variants of molten salt technology include the conceptual ''[[Dual fluid reactor]]'' which is being designed with lead as a cooling medium but molten salt fuel, commonly as the metal chloride e.g. [[Plutonium(III) chloride]], to aid in greater "nuclear waste" closed-fuel cycle capabilities.
Other notable approaches differing substantially from MSRE include the ''[[Stable Salt Reactor]]''(SSR) concept promoted by MOLTEX, which encases the molten salt in hundreds of the common solid [[fuel rod]]s that are already well established in the nuclear industry. This latter British design was found to be the most competitive for [[Small modular reactor]] development by a British-based consultancy firm ''Energy Process Development'' in 2015.<ref>[http://www.daretothink.org/europe-moltex-stable-salt-reactor/ Europe: Moltex’ Stable Salt Reactor]</ref><ref>[http://analysis.nuclearenergyinsider.com/moltex-energy-sees-uk-canada-smr-licensing-springboard-asia Moltex Energy sees UK, Canada SMR licensing as springboard to Asia Jun 28, 2016]</ref>

Another notable feature of the MSR is the possibility of a [[Thermal-neutron reactor|thermal spectrum]] nuclear [[Nuclear fuel cycle#Fuel cycles|waste-burner]]. Conventionally only fast spectrum reactors have been considered viable for [[Nuclear fuel cycle#Minor actinides recycling|utilization or reduction]] of the [[Spent nuclear fuel|spent nuclear stockpiles]]. The conceptual viability of a thermal waste-burner was first shown in a whitepaper by [[Seaborg Technologies]] spring 2015.<ref name="Seaborg Whitepaper 2015">{{cite web|url=https://seaborg.dk/s/Seaborg-whitepaper-2015.pdf|title=Thermal MSR waste burner benchmark}}</ref> Thermal waste-burning was achieved by replacing a fraction of the [[uranium]] in the spent nuclear fuel with [[thorium]]. The net production rate of [[transuranium element]] (e.g. [[plutonium]] and [[americium]]) is reduced below the consumption rate, thus reducing the magnitude of the [[Radioactive waste|nuclear storage problem]]. Without the [[nuclear proliferation]] concerns and other [[Fast-neutron reactor#Disadvantages|technical issues]] associated with a [[Fast-neutron reactor|fast reactor]].

==== Supercritical-water-cooled reactor (SCWR) ====
[[File:Supercritical-Water-Cooled Reactor.svg|right|thumb|Supercritical-Water-Cooled Reactor (SCWR)]]
{{Main article|Supercritical water reactor}}
The '''supercritical water reactor''' (SCWR)<ref name="Roadmap"/> is a [[reduced moderation water reactor]] concept that, due to the average speed of the neutrons that would cause the fission events within the fuel being faster than [[thermal neutron]]s, it is more accurately termed an [[epithermal neutron|epithermal reactor]] than a thermal reactor. It uses [[supercritical fluid|supercritical water]] as the working fluid. SCWRs are basically [[light water reactor]]s (LWR) operating at higher pressure and temperatures with a direct, once-through heat exchange cycle. As most commonly envisioned, it would operate on a direct cycle, much like a boiling water reactor ([[BWR]]), but since it uses supercritical water (not to be confused with [[Critical mass (nuclear)|critical mass]]) as the working fluid, it would have only one water phase present, which makes the supercritical heat exchange method more similar to a pressurized water reactor ([[Pressurized water reactor|PWR]]). It could operate at much higher temperatures than both current PWRs and BWRs.

Supercritical water-cooled reactors (SCWRs) are promising advanced nuclear systems because of their high [[thermal efficiency]] (i.e., about 45% vs. about 33% efficiency for current LWRs) and considerable plant simplification.

The main mission of the SCWR is generation of low-cost [[electricity]]. It is built upon two proven technologies, LWRs, which are the most commonly deployed power generating reactors in the world, and superheated [[fossil fuel]] fired [[boiler]]s, a large number of which are also in use around the world. The SCWR concept is being investigated by 32 organizations in 13 countries.{{citation needed|date=October 2012}}

Because SCWRs are water reactors they share the steam explosion and radioactive steam release hazards of BWRs and LWRs as well as the need for extremely expensive heavy duty pressure vessels, pipes, valves, and pumps. These shared problems are inherently more severe for SCWRs due to operation at higher temperatures.

A SCWR Design under development is the [[VVER]]-1700/393 (VVER-SCWR or VVER-SKD) — a Russian Supercritical-water-cooled reactor with double-inlet-core and a [[breeder reactor|breeding ratio]] of 0.95.<ref name="powertecrussia.com">{{cite web |url=http://www.powertecrussia.com/blog/tag/nuclear-power/ |title=Technology Developments & Plant Efficiency for the Russian Nuclear Power Generation Market Wednesday |date=March 24, 2010}}</ref>

=== Fast reactors ===
A [[Fast-neutron reactor|fast reactor]] directly uses the fast neutrons emitted by fission, without moderation. Unlike thermal neutron reactors, fast neutron reactors can be configured to "'''burn'''", or fission, all [[actinides]], and given enough time, therefore drastically reduce the actinides fraction in [[spent nuclear fuel]] produced by the present world fleet of thermal neutron [[light water reactor]]s, thus closing the [[nuclear fuel cycle]]. Alternatively, if configured differently, they can also [[breeder reactor|'''breed''']] more actinide fuel than they consume.

==== Gas-cooled fast reactor (GFR) ====
[[File:Gas-Cooled Fast Reactor Schemata.svg|right|thumb|Gas-Cooled Fast Reactor (GFR)]]
{{Main article|Gas-cooled fast reactor}}
The '''gas-cooled fast reactor''' (GFR)<ref name="Roadmap"/> system features a fast-neutron spectrum and closed fuel cycle for efficient conversion of [[Fertile material|fertile uranium]] and management of actinides. The reactor is [[helium]]-cooled and with an outlet temperature of 850 °C it is an evolution of the [[very-high-temperature reactor]] (VHTR) to a more sustainable fuel cycle. It will use a direct [[Brayton cycle]] [[Closed-cycle gas turbine|gas turbine]] for high thermal efficiency. Several fuel forms are being considered for their potential to operate at very high temperatures and to ensure an excellent retention of [[Nuclear fission|fission]] products: composite [[ceramic]] fuel, advanced fuel particles, or ceramic clad elements of actinide compounds. Core configurations are being considered based on pin- or plate-based fuel assemblies or prismatic blocks.

The European Sustainable Nuclear Industrial Initiative is funding three Generation IV reactor systems, one of which is a gas-cooled fast reactor, called ''Allegro'', 100 MW(t), which will be built in a central or eastern European country with construction expected to begin in 2018.<ref name="euronuclear.org">{{cite web|url=https://www.euronuclear.org/1-information/news/Gen-IV.htm |title=The European Sustainable Nuclear Industrial Initiative (ESNII) will support three Generation IV reactor systems: a sodium-cooled fast reactor, or SFR, called ''Astrid'' that is proposed by France; a gas-cooled fast reactor, GFR, called ''Allegro'' supported by central and eastern Europe; and a lead-cooled fast reactor, LFR, technology pilot called ''Myrrha'' that is proposed by Belgium. |deadurl=yes |archiveurl=https://web.archive.org/web/20131009042600/http://euronuclear.org/1-information/news/Gen-IV.htm |archivedate=2013-10-09 |df= }}</ref> The central European [[Visegrád Group]] are committed to pursuing the technology.<ref>{{cite web |url=http://www.alphagalileo.org/ViewItem.aspx?ItemId=133111&CultureCode=en |title=The V4G4 Centre of Excellence for performing joint research, development and innovation in the field of Generation-4 (G4) nuclear reactors have been established. 20 July 2013 National Center for Nuclear Research (NCBJ)}}</ref> In 2013 German, British, and French institutes finished a 3-year collaboration study on the follow on industrial scale design, known as ''GoFastR''.<ref>{{cite web|url=http://www.ist-world.org/ProjectDetails.aspx?ProjectId=5cb8f3f283574cc6b2bdbf72533172d8 |title=the European Gas cooled Fast Reactor. |deadurl=yes |archiveurl=https://web.archive.org/web/20131213091046/http://www.ist-world.org/ProjectDetails.aspx?ProjectId=5cb8f3f283574cc6b2bdbf72533172d8 |archivedate=2013-12-13 |df= }}</ref> They were funded by the EU's 7th FWP [[framework programme]], with the goal of making a sustainable VHTR.<ref>{{cite web |url=http://www.2020-horizon.com/GOFASTR-European-Gas-Cooled-Fast-Reactor%28GOFASTR%29-s312.html |title=The GOFASTR research program}}</ref>

==== Sodium-cooled fast reactor (SFR) ====
[[File:Sodium-Cooled Fast Reactor Schemata.svg|right|thumb|Pool design Sodium-Cooled Fast Reactor (SFR)]]
{{Main article|Sodium-cooled fast reactor}}
{{see also|Prototype Fast Breeder Reactor|Experimental Breeder Reactor II|S-PRISM|BN-800 reactor|Toshiba 4S|CFR-600}}

In India, the [[Fast Breeder Test Reactor]] reached criticality in October 1985. In September 2002, fuel burn-up in the FBTR for the first time reached the 100,000 megawatt-days per metric ton uranium (MWd/MTU) mark. This is considered an important milestone in breeder reactor technology. Using the experience gained from the operation of the FBTR, the [[Prototype Fast Breeder Reactor]], a 500 MWe Sodium cooled fast reactor is being built at a cost of INR 5,677 crores (~US$900 million) and is expected to be critical by June 2018. The PFBR will be followed by six more Commercial Fast Breeder Reactors (CFBRs) of 600 MWe each.

The SFR<ref name="Roadmap"/> is a project that builds on two closely related existing projects, the liquid metal [[Breeder reactor#Fast breeder reactor|fast breeder reactor]] and the [[integral fast reactor]].

The goals are to increase the efficiency of uranium usage by [[breeder reactor|breeding]] plutonium and eliminating the need for [[transuranic]] isotopes ever to leave the site. The reactor design uses an unmoderated core running on [[fast neutron]]s, designed to allow any transuranic isotope to be consumed (and in some cases used as fuel). In addition to the benefits of removing the long [[half-life]] transuranics from the waste cycle, the SFR fuel expands when the reactor overheats, and the chain reaction automatically slows down. In this manner, it is passively safe.<ref>{{cite web |url=http://www.ne.anl.gov/About/hn/logos-winter02-psr.shtml|title=Passively safe reactors rely on nature to keep them cool|author=David Baurac}}</ref>

The SFR reactor concept is cooled by liquid [[sodium]] and fueled by a metallic alloy of uranium and [[plutonium]] or [[spent nuclear fuel]], the "nuclear waste" of [[light water reactor]]s. The SFR fuel is contained in steel cladding with liquid sodium filling in the space between the clad elements which make up the fuel assembly. One of the design challenges of an SFR is the risks of handling sodium, which reacts explosively if it comes into contact with water. However, the use of liquid metal instead of water as coolant allows the system to work at atmospheric pressure, reducing the risk of leakage.

[[File:Ifr concept.jpg|thumb|375px|The sustainable fuel-cycle proposed in the 1990s [[Integral fast reactor]] concept (color), an animation of the [[pyroprocessing]] technology is also available.<ref>{{cite web |url=https://www.youtube.com/watch?v=cBThTwFhRlA |title=Historical video about the Integral Fast Reactor (IFR) concept. Uploaded by - Nuclear Engineering at Argonne}}</ref>]]
[[File:IFR concept.png|thumb|375px|IFR concept (Black and White with clearer text)]]

The European Sustainable Nuclear Industrial Initiative is funding three Generation IV reactor systems, one of which is a sodium-cooled fast reactor, called ''[[ASTRID (reactor)|ASTRID]]'', Advanced Sodium Technical Reactor for Industrial Demonstration, [[Areva]], [[Commissariat à l'énergie atomique et aux énergies alternatives|CEA]] and [[Électricité de France|EDF]] are leading the design with British collaboration.<ref>{{cite web |url=http://www.power-eng.com/articles/2010/11/areva--cea-secure.html |title=Areva, CEA secure EUR650m funding to develop ASTRID sodium-cooled Generation IV reactor 11/11/2010}}</ref><ref>{{cite web |url=http://www.powermag.com/uk-and-france-sign-landmark-civil-nuclear-cooperation-agreement/ |title=UK and France Sign Landmark Civil Nuclear Cooperation Agreement 02/22/2012 . POWERnews}}</ref> Astrid will be rated about 600 MWe and is proposed to be built in France, near to the [[Phénix]] reactor. A final decision in construction is to be made in 2019<ref name="euronuclear.org"/>

The [[China|PRC]]'s first commercial-scale, 800 MWe, fast neutron reactor, to be situated near [[Sanming]] in [[Fujian province]] will be a SFR. In 2009 an agreement was signed that would entail the Russian [[BN-800 reactor]] design to be sold to the PRC once it is completed, this would be the first time commercial-scale fast neutron reactors have ever been exported.<ref>{{cite web |url=http://www.world-nuclear-news.org/C-Joint_venture_launched_for_Chinese_fast_reactor-3004104.html |title=Joint venture launched for Chinese fast reactor}}</ref> The BN-800 reactor became operational in 2014.

The 400 MWe [[Fast Flux Test Facility]] operated successfully for ten years at the Hanford site in Washington State.

The 20 MWe [[EBR II]] operated successfully for over thirty years at the Idaho National Laboratory, until it was shut down in 1994.

GE Hitachi's [[PRISM (reactor)|PRISM]] reactor is a modernized and commercial implementation of the technology developed for the Integral Fast Reactor(IFR), developed by [[Argonne National Laboratory]] between 1984 and 1994. With the primary purpose of PRISM differing in the focus on burning up [[spent nuclear fuel]] from other reactors, rather than [[breeder reactor|breeding]] new fuel. Presented as an alternative to burying the spent fuel/waste. The design reduces the half lives of the fissionable elements present in spent nuclear fuel while generating electricity largely as a by-product.

==== Lead-cooled fast reactor (LFR) ====
[[File:Lead-Cooled Fast Reactor Schemata.svg|right|thumb|Lead-Cooled Fast Reactor (LFR)]]
{{Main article|Lead-cooled fast reactor}}
{{See also|MYRRHA}}
The '''lead-cooled fast reactor'''<ref name="Roadmap">{{cite journal|year=2002 |title=A Technology Roadmap for Generation IV Nuclear Energy Systems |last=US DOE Nuclear Energy Research Advisory Committee |volume=GIF-002-00 |url=http://nuclear.energy.gov/genIV/documents/gen_iv_roadmap.pdf |deadurl=yes |archiveurl=https://web.archive.org/web/20071129121214/http://nuclear.energy.gov/genIV/documents/gen_iv_roadmap.pdf |archivedate=2007-11-29 |df= }}</ref> features a fast-neutron-spectrum [[lead]] or [[lead]]/[[bismuth]] [[eutectic]] ([[Lead-bismuth eutectic|LBE]]) liquid-metal-cooled reactor with a closed [[Nuclear fuel cycle|fuel cycle]]. Options include a range of plant ratings, including a "battery" of 50 to 150 MW of electricity that features a very long refueling interval, a modular system rated at 300 to 400 MW, and a large monolithic plant option at 1,200 MW (The term ''battery'' refers to the long-life, factory-fabricated core, not to any provision for electrochemical energy conversion). The fuel is metal or nitride-based containing [[Fertile material|fertile uranium]] and [[transuranic]]s. The LFR is cooled by natural [[convection]] with a reactor outlet coolant temperature of 550 °C, possibly ranging up to 800 °C with advanced materials. The higher temperature enables the production of [[Thermochemical cycle|hydrogen by thermochemical processes]].

The European Sustainable Nuclear Industrial Initiative is funding three Generation IV reactor systems, one of which is a lead-cooled fast reactor that is also an [[Subcritical reactor|accelerator-driven sub-critical]] reactor, called ''[[MYRRHA]]'', 100 MW(t), which will be built in [[Belgium]] with construction expected to begin after 2014 and the industrial scale version, known as ''Alfred'', slated to be constructed sometime after 2017. A reduced-power model of Myrrha called ''Guinevere'' was started up at [[Mol, Belgium|Mol]] in March 2009.<ref name="euronuclear.org"/> In 2012 the research team reported that Guinevere was operational.<ref>{{cite news|last1=Hellemans|first1=Alexander|title=Reactor-Accelerator Hybrid Achieves Successful Test Run|url=http://news.sciencemag.org/physics/2012/01/reactor-accelerator-hybrid-achieves-successful-test-run|accessdate=29 December 2014|work=Science Insider|date=12 January 2012}}</ref>

Two other lead-cooled fast reactors under development are the SVBR-100, a modular 100 MWe lead-bismuth cooled fast neutron reactor concept designed by OKB [[Gidropress]] in Russia and the [[BREST (Reactor)|BREST-OD-300]] (Lead-cooled fast reactor) 300 MWe, to be developed after the SVBR-100, and built over 2016-20, it will dispense with the [[Uranium-238|fertile blanket]] around the core and will supersede the sodium cooled [[BN-600 reactor]] design, to purportedly give enhanced proliferation resistance.<ref name="powertecrussia.com"/>

== Advantages and disadvantages ==
Relative to current nuclear power plant technology, the claimed benefits for 4th generation reactors include:
* Nuclear waste that remains radioactive for a few centuries instead of millennia<ref>{{cite web |title=Strategies to Address Global Warming |url=http://www.columbia.edu/~jeh1/mailings/2009/20090713_Strategies.pdf}}</ref>
* 100–300 times more energy yield from the same amount of nuclear fuel<ref>{{cite web |title=4th Generation Nuclear Power |url=http://www.ossfoundation.us/projects/energy/nuclear}}</ref>
* Broader range of fuels, and even unencapsulated raw fuels (non-pebble [[Molten Salt Reactor|MSR]], [[Liquid fluoride thorium reactor|LFTR]]).
* In some reactors, the ability to consume existing nuclear waste in the production of electricity, that is, a Closed [[nuclear fuel cycle]]. This strengthens the argument to deem [[nuclear power as renewable energy]].
* Improved operating safety features, such as (depending on design) avoidance of pressurized operation, automatic passive (unpowered, uncommanded) reactor shutdown, avoidance of water cooling and the associated risks of loss of water (leaks or boiling) and hydrogen generation/explosion and contamination of coolant water.

Nuclear reactors do not emit CO2 during operation, although like all [[low carbon power]] sources, the mining and construction phase can result in CO2 emissions, if energy sources which are not carbon neutral (such as fossil fuels), or CO2 emitting cements are used during the construction process.
A 2012 [[Yale University]] review published in the Journal of Industrial Ecology analyzing {{CO2}} [[life cycle assessment]] (LCA) emissions from [[nuclear power]] determined that:<ref name="Warner + Heath, JoIE">Warner, Ethan S.; Heath, Garvin A. [http://onlinelibrary.wiley.com/doi/10.1111/j.1530-9290.2012.00472.x/full Life Cycle Greenhouse Gas Emissions of Nuclear Electricity Generation: Systematic Review and Harmonization], ''Journal of Industrial Ecology'', [[Yale University]], published online April 17, 2012, {{doi|10.1111/j.1530-9290.2012.00472.x}}</ref>
{{Quote|The collective LCA literature indicates that life cycle [[Greenhouse gas|GHG]] [greenhouse gas] emissions from nuclear power are only a fraction of traditional fossil sources and comparable to renewable technologies.}}
Although the paper primarily dealt with data from [[Generation II reactor]]s, and did not analyze the {{CO2}} emissions by 2050 of the presently under construction [[Generation III reactor]]s, it did summarize the Life Cycle Assessment findings of in development reactor technologies.{{Quote|FBRs ['[[Fast Breeder Reactor]]s'] have been evaluated in the LCA literature. The limited literature that evaluates this potential future technology reports [[median]] life cycle GHG emissions... similar to or lower than LWRs [Gen II [[light water reactor]]s] and purports to consume little or no [[uranium market|uranium ore]].}}

A specific risk of the sodium-cooled fast reactor is related to using metallic sodium as a coolant. In case of a breach, sodium explosively reacts with water. Fixing breaches may also prove dangerous, as the cheapest noble gas [[argon]] is also used to prevent sodium oxidation. Argon, like helium, can displace oxygen in the air and can pose [[hypoxia (environmental)|hypoxia]] concerns, so workers may be exposed to this additional risk. This is a pertinent problem as demonstrated by the events at the [[LMFBR|loop type]] [[Monju Nuclear Power Plant|Prototype Fast Breeder Reactor Monju]] at Tsuruga, Japan.<ref>{{cite news |title=Japan Strains to Fix a Reactor Damaged Before Quake |url=https://www.nytimes.com/2011/06/18/world/asia/18japan.html | work=The New York Times | first=Hiroko |last=Tabuchi |date=17 June 2011}}</ref>
Using lead or molten salts mitigates this problem by making the coolant less reactive and allowing a high freezing temperature and low pressure in case of a leak. Disadvantages of lead compared to sodium are much higher viscosity, much higher density, lower heat capacity, and more radioactive neutron activation products.

In many cases, there is already a large amount of experience built up with numerous proof of concept Gen IV designs. For example, the reactors at [[Fort St. Vrain Generating Station]] and [[HTR-10]] are similar to the proposed Gen IV [[VHTR]] designs, and the [[LMFBR|pool type]] [[EBR-II]], [[Phénix]] and [[BN-600]] reactor are similar to the proposed pool type Gen IV Sodium Cooled Fast reactors being designed.

== Table of designs ==

{| class=wikitable
|+ Summary of designs for generation IV reactors<ref>https://www.gen-4.org/gif/upload/docs/application/pdf/2013-09/gif_rd_outlook_for_generation_iv_nuclear_energy_systems.pdf</ref>
|-
! System
! Neutron Spectrum
! Coolant
! Temperature (°C)
! Fuel Cycle
! Size (MW)
!Example developers
|-
| [[Very-high-temperature reactor|VHTR]]
| Thermal
| Helium
| 900–1000
| Open
| 250–300
|[[Japan Atomic Energy Agency|JAEA]] ([[High-temperature engineering test reactor|HTTR]]), [[Tsinghua University]] ([[HTR-10]]), [[X-energy]]<ref name="energy.gov">{{cite web|title=Energy Department Announces New Investments in Advanced Nuclear Power Reactors...|url=https://www.energy.gov/articles/energy-department-announces-new-investments-advanced-nuclear-power-reactors-help-meet|website=[[United States Department of Energy|US Department of Energy]]|accessdate=16 January 2016}}</ref>
|-
| [[Sodium-cooled fast reactor|SFR]]
| Fast
| Sodium
| 550
| Closed
| 30–150, 300–1500, 1000–2000
|[[TerraPower]] ([[Traveling wave reactor|TWR]]), [[Toshiba]] ([[Toshiba 4S|4S]]), [[GE Hitachi Nuclear Energy]] ([[PRISM (reactor)|PRISM]])
|-
| [[Supercritical water reactor|SCWR]]
| Thermal or fast
| Water
| 510–625
| Open or closed
| 300–700, 1000–1500
|
|-
| [[Gas-cooled fast reactor|GFR]]
| Fast
| Helium
| 850
| Closed
| 1200
|[[Energy Multiplier Module]]
|-
| [[Lead-cooled fast reactor|LFR]]
| Fast
| Lead
| 480–800
| Closed
| 20–180, 300–1200, 600–1000
|
|-
| [[Molten salt reactor|MSR]]
| Fast or thermal
| Fluoride or chloride salts
| 700–800
| Closed
| 250, 1000
|[[Seaborg Technologies]], [[TerraPower]], [[Stable Salt Reactor|Moltex Energy]], [[Flibe Energy]] ([[Liquid fluoride thorium reactor|LFTR]]), [[Transatomic Power]], Thorium Tech Solution ([[Fuji Molten Salt Reactor|FUJI MSR]]), Terrestrial Energy ([[IMSR]]), [[Southern Company Services|Southern Company]]<ref name="energy.gov"/>
|-
| [[Dual fluid reactor|DFR]]
| Fast
| Lead
| 1000
| Closed
| 500–1500
| Institute for Solid-State Nuclear Physics<ref name=ifk>{{cite web |url=https://festkoerper-kernphysik.de/dfr.pdf |title=Dual Fluid Reactor - IFK |date=2013-06-16 |website=festkoerper-kernphysik.de |publisher= Institut für Festkörper-Kernphysik |format=PDF |location=Berlin, Germany |access-date=2017-08-28}}</ref>
|}

== See also ==
{{portal|Energy|Nuclear technology}}
{{colbegin}}
* [[Nuclear reactor]]
* [[Nuclear material]]
* [[Nuclear physics]]
* [[List of reactor types#Reactor types|List of reactor types]]
* [[Generation II reactor]]
* [[Generation III reactor]]
* [[Integral Fast Reactor]]
* [[Liquid fluoride thorium reactor]]
* [[Breeder reactor]]
* [[Small modular reactor]]
{{colend}}

==References==
{{Reflist|30em}}

== External links ==
* [https://inlportal.inl.gov/portal/server.pt?open=514&objID=1361&parentname=CommunityPage&parentid=10&mode=2&in_hi_userid=200&cached=true Article from Idaho National Laboratory detailing some current efforts at developing Gen. IV reactors.]
* [http://www.gen-4.org/ Generation IV International Forum (GIF)]
* [https://web.archive.org/web/20070205115654/http://nuclear.energy.gov/genIV/neGenIV1.html U.S. Department of Energy Office of Nuclear Energy, Science and Technology]
* [https://web.archive.org/web/20060512033030/http://www.engr.utk.edu/nuclear/colloquia/slides/Gen%20IV%20U-Tenn%20Presentation.pdf Gen IV presentation]
* [http://www.ecology.at/ecology/files/pr577_1.pdf Science or Fiction - Is there a Future for Nuclear?] (Nov. 2007) - A publication from the Austrian [[Ecology Institute (Austria)|Ecology Institute]] about 'Generation IV' and Fusion reactors.
* {{cite web |url=http://memagazine.asme.org/Articles/2011/December/Nuclear_Power_After_Fukushima.cfm |title=Nuclear Power After Fukushima |author=Gail H. Marcus |date=December 2011 |work=Mechanical Engineering (the magazine of [[ASME]]) |accessdate=23 January 2012}} "In the wake of a severe plant accident, advanced reactor designs are getting renewed attention."
* [http://www.itheo.org/ International Thorium Energy Organisation - www.IThEO.org]
* [http://www.ithec.org/ International Thorium Energy Committee - iThEC]

{{Nuclear fission reactors}}

[[Category:Nuclear power reactor types]]
[[Category:Idaho National Laboratory]]

Benutzer:Snackroeg/Kernreaktoren der Generation 5

2018-04-15T20:26:37Z

Boundarylayer: /* Sodium-cooled fast reactor (SFR) */

{{update|date=October 2017}}
[[File:GenIVRoadmap-en.svg|thumb|480px|Nuclear Energy Systems Deployable no later than 2030 and offering significant advances in sustainability, safety and reliability, and economics]]

'''Generation IV reactors''' ('''Gen IV''') are a set of [[nuclear reactor]] designs currently being researched for commercial applications by the Generation IV International Forum, with [[Technology readiness level]]s varying between the level requiring a demonstration, to economical competitive implementation.<ref>{{Cite journal|last=Locatelli|first=Giorgio|last2=Mancini|first2=Mauro|last3=Todeschini|first3=Nicola|date=2013-10-01|title=Generation IV nuclear reactors: Current status and future prospects|url=http://www.sciencedirect.com/science/article/pii/S0301421513006083|journal=Energy Policy|volume=61|pages=1503–1520|doi=10.1016/j.enpol.2013.06.101}}</ref> They are motivated by a variety of goals including improved safety, sustainability, efficiency, and cost.

The most developed Gen IV reactor design, the [[sodium fast reactor]], has received the greatest share of funding over the years, with the principle Gen IV aspect of the design, relating in largest part to the development of a sustainable [[Integral_fast_reactor#Fuel_cycle|closed fuel cycle]] for the reactor. Amongst nuclear engineers the [[molten-salt reactor]], the least developed and funded technology, is considered as potentially having the greatest [[inherent safety]] of the six models.<ref>[https://www.scientificamerican.com/article/can-sodium-save-nuclear-power/ Can Sodium Save Nuclear Power? Scientific American]</ref><ref>{{cite journal |last1=Moir |first1=Ralph |last2=Teller |first2=Edward |year=2005 |title=Thorium-Fueled Underground Power Plant Based on Molten Salt Technology |journal=Nuclear Technology |volume=151 |issue=3 |pages=334–340 |publisher=[[American Nuclear Society]] |url=http://www.new.ans.org/pubs/journals/nt/a_3655 |accessdate=March 22, 2012 }}</ref> While the [[hydrogen economy]], the use of hydrogen to produce [[Carbon-neutral fuel]]s, is deemed as strengthening the economic case for the two most efficient models, the [[Very-high-temperature reactor|high temperature reactor]] designs.<ref>[https://www.sciencedirect.com/science/article/pii/S0301421513006083 Generation IV nuclear reactors: Current status and future prospects doi.org/10.1016/j.enpol.2013.06.101]</ref>

The majority of the 6 designs are generally not expected to be available for commercial construction until 2020–30.<ref name="Generation IV">[http://www.world-nuclear.org/info/Nuclear-Fuel-Cycle/Power-Reactors/Generation-IV-Nuclear-Reactors/]</ref> Presently the majority of reactors in operation around the world are considered [[Generation II reactor|second generation reactor]] systems, as the vast majority of the [[Nuclear reactor#Classification by generation|first generation]] systems were retired some time ago, and there are only a dozen or so [[Generation III reactor]]s in operation as of 2014.
[[Nuclear reactor#Generation V+ reactors|Generation V reactors]] refer to reactors that are purely theoretical and are therefore not yet considered feasible in the short term, resulting in limited [[R&D]] funding.

== History ==
The Generation IV International Forum (GIF) is "a co-operative international endeavour which was set up to carry out the research and development needed to establish the feasibility and performance capabilities of the next generation nuclear energy systems."<ref>{{Cite web|url=https://www.gen-4.org/gif/jcms/c_9260/public|title=GIF Portal - Home - Public|website=www.gen-4.org|access-date=2016-07-25}}</ref> It was founded in 2001. Currently active members of the Generation IV International Forum (GIF) include: [[Australia]], [[Canada]], [[China]], the [[European Atomic Energy Community]] (Euratom), [[France]], [[Japan]], [[Russia]], [[South Africa]], [[South Korea]], [[Switzerland]], and the [[United States]]. The non-active members are [[Argentina]], [[Brazil]], and the [[United Kingdom]].<ref name="gen-4">{{cite web|url=https://www.gen-4.org/gif/jcms/c_9492/members|title=GIF Membership|website=gen-4.org|accessdate=28 October 2014}}</ref> Switzerland joined in 2002, Euratom in 2003, and China and Russia in 2006. The remaining countries (excluding Australia) were founding members.<ref name="gen-4" />

The 36th GIF meeting in [[Brussels]] was held in November 2013.<ref>{{cite web|url=https://www.energy.gov/ne/articles/generation-iv-international-forum-updates-technology-roadmap-and-builds-future|title=generation IV international forum updates technology roadmap and builds future. DOE}}</ref><ref>{{cite web|url=http://events.r20.constantcontact.com/register/event?llr=mscrkjkab&oeidk=a07e7melf609716b2c6 |title=The Generation IV international forum holds their 36th meeting on Monday 18th Nov 2013 in Brussels. }}{{dead link|date=January 2017 |bot=InternetArchiveBot |fix-attempted=yes }}</ref> The ''Technology Roadmap Update for Generation IV Nuclear Energy Systems'' was published in January 2014 which details R&D objectives for the next decade.<ref>[https://web.archive.org/web/20140625102915/https://www.gen-4.org/gif/upload/docs/application/pdf/2014-03/gif-tru2014.pdf Technology Roadmap Update for Generation IV Nuclear Energy Systems]</ref> A breakdown of the reactor designs being researched by each forum member has been made available.<ref>[https://web.archive.org/web/20140708023538/https://www.gen-4.org/gif/upload/docs/application/pdf/2014-03/gif_overview_presentation_v9_final3_web.pdf Generation IV International Forum, overview, John E. Kelly, page 15]</ref>

[[Nuclear power in Australia|Australia]] joined the forum in 2016.<ref>https://archive.is/20160907131656/https://www.gen-4.org/gif/jcms/c_71564/australia-joins-the-generation-iv-international-forum</ref>

In January 2018, it was reported that "the first installation of the pressure vessel cover of the world's first Gen IV reactor" had been completed on the [[HTR-PM]].<ref>http://www.world-nuclear-news.org/NN-First-HTR-PM-vessel-head-in-place-0401185.html</ref>

== Reactor types ==
Many reactor types were considered initially; however, the list was downsized to focus on the most promising technologies and those that could most likely meet the goals of the Gen IV initiative.<ref name="Generation IV"/> Three systems are nominally [[thermal reactor]]s and four are [[fast reactor]]s. The Very High Temperature Reactor (VHTR) is also being researched for potentially providing high quality process heat for [[thermochemical cycle|hydrogen production]]. The fast reactors offer the possibility of burning [[actinides]] to further reduce waste and of being able to "[[breeder reactor|breed more fuel]]" than they consume. These systems offer significant advances in sustainability, safety and reliability, economics, proliferation resistance (depending on perspective) and physical protection.

=== Thermal reactors ===
A [[Thermal-neutron reactor|thermal reactor]] is a [[nuclear reactor]] that uses slow or [[thermal neutrons]]. A [[neutron moderator]] is used to slow the [[neutron]]s emitted by fission to make them more likely to be captured by the fuel.

==== Very-high-temperature reactor (VHTR) ====
[[File:Very High Temperature Reactor.svg|right|thumb|Very-High-Temperature Reactor (VHTR)]]
{{Main article|Very high temperature reactor}}
{{see also|Fort St. Vrain Generating Station|High-temperature engineering test reactor|HTR-10}}
The '''very high temperature reactor''' concept uses a [[graphite]]-moderated core with a once-through [[uranium]] fuel cycle, using helium or molten salt as the [[Very high temperature reactor#Coolant|coolant]]. This reactor design envisions an outlet temperature of 1,000 °C. The reactor core can be either a prismatic-block or a [[pebble bed reactor]] design. The high temperatures enable applications such as process heat or [[hydrogen]] production via the thermochemical [[Sulfur-iodine cycle|iodine-sulfur]] process. It would also be [[Passive nuclear safety|passively safe]].

The planned construction of the first VHTR, the South African PBMR ([[pebble bed modular reactor]]), lost government funding in February, 2010.<ref>[http://www.powergenworldwide.com/index/display/articledisplay/6322207443/articles/power-engineering-international/volume-18/Issue_3/regulars/world-news/INTERNATIONAL.html South Africa to stop funding Pebble Bed nuclear reactor] {{webarchive|url=https://web.archive.org/web/20100909172743/http://www.powergenworldwide.com/index/display/articledisplay/6322207443/articles/power-engineering-international/volume-18/Issue_3/regulars/world-news/INTERNATIONAL.html |date=2010-09-09 }}</ref> A pronounced increase of costs and concerns about possible unexpected technical problems had discouraged potential investors and customers.

The [[Peoples Republic of China]] began construction of a 200-MW High Temperature Pebble bed reactor in 2012 as a successor to its [[HTR-10]].<ref>[http://www.nucnet.org/all-the-news/2013/01/07/china-begins-construction-of-first-generation-iv-htr-pm-unit Nucnet Report: 'China Begins Construction of First Generation IV HTR-PM Unit', 7 January 2013]</ref>

Also in 2012, as part of the [[Next Generation Nuclear Plant]] competition, [[Idaho National Laboratory]] approved a design similar to [[Areva]]'s prismatic block [http://us.areva.com/EN/home-3225/areva-inc-areva-htgr.html Antares reactor] as the chosen [[HTGR]] to be deployed as a prototype by 2021. It was in competition with [[General Atomics]]' [[Gas turbine modular helium reactor]] and [[Westinghouse Electric Company|Westinghouse]]'s [[Pebble Bed Modular Reactor]].<ref name="World nuclear news">{{cite web|url=http://www.world-nuclear-news.org/NN-Areva_modular_reactor_selected_for_NGNP_development-1502124.html|title=INL approves Antares design}}</ref>

[[X-energy]] was awarded a five-year $53M U.S. Department of Energy Advanced Reactor Concept Cooperative Agreement award to advance elements of their reactor development.<ref>[https://www.x-energy.com/doe-partnership]</ref>
The [[X-energy#Reactor Design|Xe-100]] is a pebble-bed modular reactor and will generate 200-MWt and approximately 76-MWe. The standard Xe-100 "four-pack" plant generates approximately 300-MWe and will fit on as few as 13 acres. All of the components for the Xe-100 will be road-transportable, and will be installed, rather than constructed, at the project site to streamline construction.<ref name="X-energy">{{cite web|url=https://www.x-energy.com/}}</ref>

==== Molten-salt reactor (MSR) ====
[[File:Molten Salt Reactor.svg|right|thumb|Molten Salt Reactor (MSR)]]
{{Main article|Molten salt reactor}}
{{see also|Liquid fluoride thorium reactor}}
A '''molten salt reactor'''<ref name="Roadmap"/> is a type of [[nuclear reactor]] where the primary [[coolant]], or even the fuel itself is a molten salt mixture. There have been many designs put forward for this type of reactor and a few prototypes built. The early concepts and many current ones rely on [[nuclear fuel]], perhaps [[uranium tetrafluoride]] (UF4) or [[thorium tetrafluoride]] (ThF4), dissolved in molten [[fluoride]] salt. The fluid would reach [[Nuclear reactor physics#Criticality|criticality]] by flowing into a core where [[graphite]] would serve as the [[neutron moderator|moderator]]. Many current concepts rely on fuel that is dispersed in a graphite matrix with the molten salt providing low pressure, high temperature cooling.

The Gen IV MSR is more accurately termed an [[epithermal neutron|epithermal reactor]] than a thermal reactor due to the average speed of the neutrons that would cause the fission events within its fuel being faster than [[thermal neutron]]s.<ref>{{cite web |url=https://inlportal.inl.gov/portal/server.pt?open=514&objID=1361&parentname=CommunityPage&parentid=10&mode=2&in_hi_userid=200&cached=true |title=Idaho National Laboratory detailing some current efforts at developing Gen. IV reactors}}</ref>

The principle of a MSR can be used for thermal, epithermal and fast reactors. Since 2005 the focus has moved towards a fast spectrum MSR (MSFR).<ref>H. Boussier, S. Delpech, V. Ghetta et Al. : The Molten Salt Reactor (MSR) in Generation IV: Overview and Perspectives, GIF SYMPOSIUM PROCEEDINGS/2012 ANNUAL REPORT, NEA No. 7141, pp95 [https://www.gen-4.org/gif/jcms/c_44720/annual-reports]
</ref>

While most MSR designs being pursued are largely derived from the 1960s [[Molten-Salt Reactor Experiment]] (MSRE), variants of molten salt technology include the conceptual ''[[Dual fluid reactor]]'' which is being designed with lead as a cooling medium but molten salt fuel, commonly as the metal chloride e.g. [[Plutonium(III) chloride]], to aid in greater "nuclear waste" closed-fuel cycle capabilities.
Other notable approaches differing substantially from MSRE include the ''[[Stable Salt Reactor]]''(SSR) concept promoted by MOLTEX, which encases the molten salt in hundreds of the common solid [[fuel rod]]s that are already well established in the nuclear industry. This latter British design was found to be the most competitive for [[Small modular reactor]] development by a British-based consultancy firm ''Energy Process Development'' in 2015.<ref>[http://www.daretothink.org/europe-moltex-stable-salt-reactor/ Europe: Moltex’ Stable Salt Reactor]</ref><ref>[http://analysis.nuclearenergyinsider.com/moltex-energy-sees-uk-canada-smr-licensing-springboard-asia Moltex Energy sees UK, Canada SMR licensing as springboard to Asia Jun 28, 2016]</ref>

Another notable feature of the MSR is the possibility of a [[Thermal-neutron reactor|thermal spectrum]] nuclear [[Nuclear fuel cycle#Fuel cycles|waste-burner]]. Conventionally only fast spectrum reactors have been considered viable for [[Nuclear fuel cycle#Minor actinides recycling|utilization or reduction]] of the [[Spent nuclear fuel|spent nuclear stockpiles]]. The conceptual viability of a thermal waste-burner was first shown in a whitepaper by [[Seaborg Technologies]] spring 2015.<ref name="Seaborg Whitepaper 2015">{{cite web|url=https://seaborg.dk/s/Seaborg-whitepaper-2015.pdf|title=Thermal MSR waste burner benchmark}}</ref> Thermal waste-burning was achieved by replacing a fraction of the [[uranium]] in the spent nuclear fuel with [[thorium]]. The net production rate of [[transuranium element]] (e.g. [[plutonium]] and [[americium]]) is reduced below the consumption rate, thus reducing the magnitude of the [[Radioactive waste|nuclear storage problem]]. Without the [[nuclear proliferation]] concerns and other [[Fast-neutron reactor#Disadvantages|technical issues]] associated with a [[Fast-neutron reactor|fast reactor]].

==== Supercritical-water-cooled reactor (SCWR) ====
[[File:Supercritical-Water-Cooled Reactor.svg|right|thumb|Supercritical-Water-Cooled Reactor (SCWR)]]
{{Main article|Supercritical water reactor}}
The '''supercritical water reactor''' (SCWR)<ref name="Roadmap"/> is a [[reduced moderation water reactor]] concept that, due to the average speed of the neutrons that would cause the fission events within the fuel being faster than [[thermal neutron]]s, it is more accurately termed an [[epithermal neutron|epithermal reactor]] than a thermal reactor. It uses [[supercritical fluid|supercritical water]] as the working fluid. SCWRs are basically [[light water reactor]]s (LWR) operating at higher pressure and temperatures with a direct, once-through heat exchange cycle. As most commonly envisioned, it would operate on a direct cycle, much like a boiling water reactor ([[BWR]]), but since it uses supercritical water (not to be confused with [[Critical mass (nuclear)|critical mass]]) as the working fluid, it would have only one water phase present, which makes the supercritical heat exchange method more similar to a pressurized water reactor ([[Pressurized water reactor|PWR]]). It could operate at much higher temperatures than both current PWRs and BWRs.

Supercritical water-cooled reactors (SCWRs) are promising advanced nuclear systems because of their high [[thermal efficiency]] (i.e., about 45% vs. about 33% efficiency for current LWRs) and considerable plant simplification.

The main mission of the SCWR is generation of low-cost [[electricity]]. It is built upon two proven technologies, LWRs, which are the most commonly deployed power generating reactors in the world, and superheated [[fossil fuel]] fired [[boiler]]s, a large number of which are also in use around the world. The SCWR concept is being investigated by 32 organizations in 13 countries.{{citation needed|date=October 2012}}

Because SCWRs are water reactors they share the steam explosion and radioactive steam release hazards of BWRs and LWRs as well as the need for extremely expensive heavy duty pressure vessels, pipes, valves, and pumps. These shared problems are inherently more severe for SCWRs due to operation at higher temperatures.

A SCWR Design under development is the [[VVER]]-1700/393 (VVER-SCWR or VVER-SKD) — a Russian Supercritical-water-cooled reactor with double-inlet-core and a [[breeder reactor|breeding ratio]] of 0.95.<ref name="powertecrussia.com">{{cite web |url=http://www.powertecrussia.com/blog/tag/nuclear-power/ |title=Technology Developments & Plant Efficiency for the Russian Nuclear Power Generation Market Wednesday |date=March 24, 2010}}</ref>

=== Fast reactors ===
A [[Fast-neutron reactor|fast reactor]] directly uses the fast neutrons emitted by fission, without moderation. Unlike thermal neutron reactors, fast neutron reactors can be configured to "'''burn'''", or fission, all [[actinides]], and given enough time, therefore drastically reduce the actinides fraction in [[spent nuclear fuel]] produced by the present world fleet of thermal neutron [[light water reactor]]s, thus closing the [[nuclear fuel cycle]]. Alternatively, if configured differently, they can also [[breeder reactor|'''breed''']] more actinide fuel than they consume.

==== Gas-cooled fast reactor (GFR) ====
[[File:Gas-Cooled Fast Reactor Schemata.svg|right|thumb|Gas-Cooled Fast Reactor (GFR)]]
{{Main article|Gas-cooled fast reactor}}
The '''gas-cooled fast reactor''' (GFR)<ref name="Roadmap"/> system features a fast-neutron spectrum and closed fuel cycle for efficient conversion of [[Fertile material|fertile uranium]] and management of actinides. The reactor is [[helium]]-cooled and with an outlet temperature of 850 °C it is an evolution of the [[very-high-temperature reactor]] (VHTR) to a more sustainable fuel cycle. It will use a direct [[Brayton cycle]] [[Closed-cycle gas turbine|gas turbine]] for high thermal efficiency. Several fuel forms are being considered for their potential to operate at very high temperatures and to ensure an excellent retention of [[Nuclear fission|fission]] products: composite [[ceramic]] fuel, advanced fuel particles, or ceramic clad elements of actinide compounds. Core configurations are being considered based on pin- or plate-based fuel assemblies or prismatic blocks.

The European Sustainable Nuclear Industrial Initiative is funding three Generation IV reactor systems, one of which is a gas-cooled fast reactor, called ''Allegro'', 100 MW(t), which will be built in a central or eastern European country with construction expected to begin in 2018.<ref name="euronuclear.org">{{cite web|url=https://www.euronuclear.org/1-information/news/Gen-IV.htm |title=The European Sustainable Nuclear Industrial Initiative (ESNII) will support three Generation IV reactor systems: a sodium-cooled fast reactor, or SFR, called ''Astrid'' that is proposed by France; a gas-cooled fast reactor, GFR, called ''Allegro'' supported by central and eastern Europe; and a lead-cooled fast reactor, LFR, technology pilot called ''Myrrha'' that is proposed by Belgium. |deadurl=yes |archiveurl=https://web.archive.org/web/20131009042600/http://euronuclear.org/1-information/news/Gen-IV.htm |archivedate=2013-10-09 |df= }}</ref> The central European [[Visegrád Group]] are committed to pursuing the technology.<ref>{{cite web |url=http://www.alphagalileo.org/ViewItem.aspx?ItemId=133111&CultureCode=en |title=The V4G4 Centre of Excellence for performing joint research, development and innovation in the field of Generation-4 (G4) nuclear reactors have been established. 20 July 2013 National Center for Nuclear Research (NCBJ)}}</ref> In 2013 German, British, and French institutes finished a 3-year collaboration study on the follow on industrial scale design, known as ''GoFastR''.<ref>{{cite web|url=http://www.ist-world.org/ProjectDetails.aspx?ProjectId=5cb8f3f283574cc6b2bdbf72533172d8 |title=the European Gas cooled Fast Reactor. |deadurl=yes |archiveurl=https://web.archive.org/web/20131213091046/http://www.ist-world.org/ProjectDetails.aspx?ProjectId=5cb8f3f283574cc6b2bdbf72533172d8 |archivedate=2013-12-13 |df= }}</ref> They were funded by the EU's 7th FWP [[framework programme]], with the goal of making a sustainable VHTR.<ref>{{cite web |url=http://www.2020-horizon.com/GOFASTR-European-Gas-Cooled-Fast-Reactor%28GOFASTR%29-s312.html |title=The GOFASTR research program}}</ref>

==== Sodium-cooled fast reactor (SFR) ====
[[File:Sodium-Cooled Fast Reactor Schemata.svg|right|thumb|Pool design Sodium-Cooled Fast Reactor (SFR)]]
{{Main article|Sodium-cooled fast reactor}}
{{see also|Prototype Fast Breeder Reactor|Experimental Breeder Reactor II|S-PRISM|BN-800 reactor|Toshiba 4S|CFR-600}}

In India, the [[Fast Breeder Test Reactor]] reached criticality in October 1985. In September 2002, fuel burn-up in the FBTR for the first time reached the 100,000 megawatt-days per metric ton uranium (MWd/MTU) mark. This is considered an important milestone in breeder reactor technology. Using the experience gained from the operation of the FBTR, the [[Prototype Fast Breeder Reactor]], a 500 MWe Sodium cooled fast reactor is being built at a cost of INR 5,677 crores (~US$900 million) and is expected to be critical by June 2018. The PFBR will be followed by six more Commercial Fast Breeder Reactors (CFBRs) of 600 MWe each.

The SFR<ref name="Roadmap"/> is a project that builds on two closely related existing projects, the liquid metal [[Breeder reactor#Fast breeder reactor|fast breeder reactor]] and the [[integral fast reactor]].

The goals are to increase the efficiency of uranium usage by [[breeder reactor|breeding]] plutonium and eliminating the need for [[transuranic]] isotopes ever to leave the site. The reactor design uses an unmoderated core running on [[fast neutron]]s, designed to allow any transuranic isotope to be consumed (and in some cases used as fuel). In addition to the benefits of removing the long [[half-life]] transuranics from the waste cycle, the SFR fuel expands when the reactor overheats, and the chain reaction automatically slows down. In this manner, it is passively safe.<ref>{{cite web |url=http://www.ne.anl.gov/About/hn/logos-winter02-psr.shtml|title=Passively safe reactors rely on nature to keep them cool|author=David Baurac}}</ref>

The SFR reactor concept is cooled by liquid [[sodium]] and fueled by a metallic alloy of uranium and [[plutonium]] or [[spent nuclear fuel]], the "nuclear waste" of [[light water reactor]]s. The SFR fuel is contained in steel cladding with liquid sodium filling in the space between the clad elements which make up the fuel assembly. One of the design challenges of an SFR is the risks of handling sodium, which reacts explosively if it comes into contact with water. However, the use of liquid metal instead of water as coolant allows the system to work at atmospheric pressure, reducing the risk of leakage.

[[File:Ifr concept.jpg|thumb|375px|The sustainable fuel-cycle proposed in the 1990s [[Integral fast reactor]] concept (color), an animation of the [[pyroprocessing]] technology is also available.<ref>{{cite web |url=https://www.youtube.com/watch?v=cBThTwFhRlA |title=Historical video about the Integral Fast Reactor (IFR) concept. Uploaded by - Nuclear Engineering at Argonne}}</ref>]]
[[File:IFR concept.png|thumb|375px|IFR concept (Black and White with clearer text)]]

The European Sustainable Nuclear Industrial Initiative is funding three Generation IV reactor systems, one of which is a sodium-cooled fast reactor, called ''[[ASTRID (reactor)|ASTRID]]'', Advanced Sodium Technical Reactor for Industrial Demonstration, [[Areva]], [[Commissariat à l'énergie atomique et aux énergies alternatives|CEA]] and [[Électricité de France|EDF]] are leading the design with British collaboration.<ref>{{cite web |url=http://www.power-eng.com/articles/2010/11/areva--cea-secure.html |title=Areva, CEA secure EUR650m funding to develop ASTRID sodium-cooled Generation IV reactor 11/11/2010}}</ref><ref>{{cite web |url=http://www.powermag.com/uk-and-france-sign-landmark-civil-nuclear-cooperation-agreement/ |title=UK and France Sign Landmark Civil Nuclear Cooperation Agreement 02/22/2012 . POWERnews}}</ref> Astrid will be rated about 600 MWe and is proposed to be built in France, near to the [[Phénix]] reactor. A final decision in construction is to be made in 2019<ref name="euronuclear.org"/>

The [[China|PRC]]'s first commercial-scale, 800 MWe, fast neutron reactor, to be situated near [[Sanming]] in [[Fujian province]] will be a SFR. In 2009 an agreement was signed that would entail the Russian [[BN-800 reactor]] design to be sold to the PRC once it is completed, this would be the first time commercial-scale fast neutron reactors have ever been exported.<ref>{{cite web |url=http://www.world-nuclear-news.org/C-Joint_venture_launched_for_Chinese_fast_reactor-3004104.html |title=Joint venture launched for Chinese fast reactor}}</ref> The BN-800 reactor became operational in 2014.

The 400 MWe [[Fast Flux Test Facility]] operated successfully for ten years at the Hanford site in Washington State.

The 20 MWe [[EBR II]] operated successfully for over thirty years at the Idaho National Laboratory, until it was shut down in 1994.

GE Hitachi's [[PRISM (reactor)|PRISM]] reactor is an SFR with the primary purpose of reducing the half lives of the fissionable elements present in used nuclear fuel while generating electricity largely as a by-product.

==== Lead-cooled fast reactor (LFR) ====
[[File:Lead-Cooled Fast Reactor Schemata.svg|right|thumb|Lead-Cooled Fast Reactor (LFR)]]
{{Main article|Lead-cooled fast reactor}}
{{See also|MYRRHA}}
The '''lead-cooled fast reactor'''<ref name="Roadmap">{{cite journal|year=2002 |title=A Technology Roadmap for Generation IV Nuclear Energy Systems |last=US DOE Nuclear Energy Research Advisory Committee |volume=GIF-002-00 |url=http://nuclear.energy.gov/genIV/documents/gen_iv_roadmap.pdf |deadurl=yes |archiveurl=https://web.archive.org/web/20071129121214/http://nuclear.energy.gov/genIV/documents/gen_iv_roadmap.pdf |archivedate=2007-11-29 |df= }}</ref> features a fast-neutron-spectrum [[lead]] or [[lead]]/[[bismuth]] [[eutectic]] ([[Lead-bismuth eutectic|LBE]]) liquid-metal-cooled reactor with a closed [[Nuclear fuel cycle|fuel cycle]]. Options include a range of plant ratings, including a "battery" of 50 to 150 MW of electricity that features a very long refueling interval, a modular system rated at 300 to 400 MW, and a large monolithic plant option at 1,200 MW (The term ''battery'' refers to the long-life, factory-fabricated core, not to any provision for electrochemical energy conversion). The fuel is metal or nitride-based containing [[Fertile material|fertile uranium]] and [[transuranic]]s. The LFR is cooled by natural [[convection]] with a reactor outlet coolant temperature of 550 °C, possibly ranging up to 800 °C with advanced materials. The higher temperature enables the production of [[Thermochemical cycle|hydrogen by thermochemical processes]].

The European Sustainable Nuclear Industrial Initiative is funding three Generation IV reactor systems, one of which is a lead-cooled fast reactor that is also an [[Subcritical reactor|accelerator-driven sub-critical]] reactor, called ''[[MYRRHA]]'', 100 MW(t), which will be built in [[Belgium]] with construction expected to begin after 2014 and the industrial scale version, known as ''Alfred'', slated to be constructed sometime after 2017. A reduced-power model of Myrrha called ''Guinevere'' was started up at [[Mol, Belgium|Mol]] in March 2009.<ref name="euronuclear.org"/> In 2012 the research team reported that Guinevere was operational.<ref>{{cite news|last1=Hellemans|first1=Alexander|title=Reactor-Accelerator Hybrid Achieves Successful Test Run|url=http://news.sciencemag.org/physics/2012/01/reactor-accelerator-hybrid-achieves-successful-test-run|accessdate=29 December 2014|work=Science Insider|date=12 January 2012}}</ref>

Two other lead-cooled fast reactors under development are the SVBR-100, a modular 100 MWe lead-bismuth cooled fast neutron reactor concept designed by OKB [[Gidropress]] in Russia and the [[BREST (Reactor)|BREST-OD-300]] (Lead-cooled fast reactor) 300 MWe, to be developed after the SVBR-100, and built over 2016-20, it will dispense with the [[Uranium-238|fertile blanket]] around the core and will supersede the sodium cooled [[BN-600 reactor]] design, to purportedly give enhanced proliferation resistance.<ref name="powertecrussia.com"/>

== Advantages and disadvantages ==
Relative to current nuclear power plant technology, the claimed benefits for 4th generation reactors include:
* Nuclear waste that remains radioactive for a few centuries instead of millennia<ref>{{cite web |title=Strategies to Address Global Warming |url=http://www.columbia.edu/~jeh1/mailings/2009/20090713_Strategies.pdf}}</ref>
* 100–300 times more energy yield from the same amount of nuclear fuel<ref>{{cite web |title=4th Generation Nuclear Power |url=http://www.ossfoundation.us/projects/energy/nuclear}}</ref>
* Broader range of fuels, and even unencapsulated raw fuels (non-pebble [[Molten Salt Reactor|MSR]], [[Liquid fluoride thorium reactor|LFTR]]).
* In some reactors, the ability to consume existing nuclear waste in the production of electricity, that is, a Closed [[nuclear fuel cycle]]. This strengthens the argument to deem [[nuclear power as renewable energy]].
* Improved operating safety features, such as (depending on design) avoidance of pressurized operation, automatic passive (unpowered, uncommanded) reactor shutdown, avoidance of water cooling and the associated risks of loss of water (leaks or boiling) and hydrogen generation/explosion and contamination of coolant water.

Nuclear reactors do not emit CO2 during operation, although like all [[low carbon power]] sources, the mining and construction phase can result in CO2 emissions, if energy sources which are not carbon neutral (such as fossil fuels), or CO2 emitting cements are used during the construction process.
A 2012 [[Yale University]] review published in the Journal of Industrial Ecology analyzing {{CO2}} [[life cycle assessment]] (LCA) emissions from [[nuclear power]] determined that:<ref name="Warner + Heath, JoIE">Warner, Ethan S.; Heath, Garvin A. [http://onlinelibrary.wiley.com/doi/10.1111/j.1530-9290.2012.00472.x/full Life Cycle Greenhouse Gas Emissions of Nuclear Electricity Generation: Systematic Review and Harmonization], ''Journal of Industrial Ecology'', [[Yale University]], published online April 17, 2012, {{doi|10.1111/j.1530-9290.2012.00472.x}}</ref>
{{Quote|The collective LCA literature indicates that life cycle [[Greenhouse gas|GHG]] [greenhouse gas] emissions from nuclear power are only a fraction of traditional fossil sources and comparable to renewable technologies.}}
Although the paper primarily dealt with data from [[Generation II reactor]]s, and did not analyze the {{CO2}} emissions by 2050 of the presently under construction [[Generation III reactor]]s, it did summarize the Life Cycle Assessment findings of in development reactor technologies.{{Quote|FBRs ['[[Fast Breeder Reactor]]s'] have been evaluated in the LCA literature. The limited literature that evaluates this potential future technology reports [[median]] life cycle GHG emissions... similar to or lower than LWRs [Gen II [[light water reactor]]s] and purports to consume little or no [[uranium market|uranium ore]].}}

A specific risk of the sodium-cooled fast reactor is related to using metallic sodium as a coolant. In case of a breach, sodium explosively reacts with water. Fixing breaches may also prove dangerous, as the cheapest noble gas [[argon]] is also used to prevent sodium oxidation. Argon, like helium, can displace oxygen in the air and can pose [[hypoxia (environmental)|hypoxia]] concerns, so workers may be exposed to this additional risk. This is a pertinent problem as demonstrated by the events at the [[LMFBR|loop type]] [[Monju Nuclear Power Plant|Prototype Fast Breeder Reactor Monju]] at Tsuruga, Japan.<ref>{{cite news |title=Japan Strains to Fix a Reactor Damaged Before Quake |url=https://www.nytimes.com/2011/06/18/world/asia/18japan.html | work=The New York Times | first=Hiroko |last=Tabuchi |date=17 June 2011}}</ref>
Using lead or molten salts mitigates this problem by making the coolant less reactive and allowing a high freezing temperature and low pressure in case of a leak. Disadvantages of lead compared to sodium are much higher viscosity, much higher density, lower heat capacity, and more radioactive neutron activation products.

In many cases, there is already a large amount of experience built up with numerous proof of concept Gen IV designs. For example, the reactors at [[Fort St. Vrain Generating Station]] and [[HTR-10]] are similar to the proposed Gen IV [[VHTR]] designs, and the [[LMFBR|pool type]] [[EBR-II]], [[Phénix]] and [[BN-600]] reactor are similar to the proposed pool type Gen IV Sodium Cooled Fast reactors being designed.

== Table of designs ==

{| class=wikitable
|+ Summary of designs for generation IV reactors<ref>https://www.gen-4.org/gif/upload/docs/application/pdf/2013-09/gif_rd_outlook_for_generation_iv_nuclear_energy_systems.pdf</ref>
|-
! System
! Neutron Spectrum
! Coolant
! Temperature (°C)
! Fuel Cycle
! Size (MW)
!Example developers
|-
| [[Very-high-temperature reactor|VHTR]]
| Thermal
| Helium
| 900–1000
| Open
| 250–300
|[[Japan Atomic Energy Agency|JAEA]] ([[High-temperature engineering test reactor|HTTR]]), [[Tsinghua University]] ([[HTR-10]]), [[X-energy]]<ref name="energy.gov">{{cite web|title=Energy Department Announces New Investments in Advanced Nuclear Power Reactors...|url=https://www.energy.gov/articles/energy-department-announces-new-investments-advanced-nuclear-power-reactors-help-meet|website=[[United States Department of Energy|US Department of Energy]]|accessdate=16 January 2016}}</ref>
|-
| [[Sodium-cooled fast reactor|SFR]]
| Fast
| Sodium
| 550
| Closed
| 30–150, 300–1500, 1000–2000
|[[TerraPower]] ([[Traveling wave reactor|TWR]]), [[Toshiba]] ([[Toshiba 4S|4S]]), [[GE Hitachi Nuclear Energy]] ([[PRISM (reactor)|PRISM]])
|-
| [[Supercritical water reactor|SCWR]]
| Thermal or fast
| Water
| 510–625
| Open or closed
| 300–700, 1000–1500
|
|-
| [[Gas-cooled fast reactor|GFR]]
| Fast
| Helium
| 850
| Closed
| 1200
|[[Energy Multiplier Module]]
|-
| [[Lead-cooled fast reactor|LFR]]
| Fast
| Lead
| 480–800
| Closed
| 20–180, 300–1200, 600–1000
|
|-
| [[Molten salt reactor|MSR]]
| Fast or thermal
| Fluoride or chloride salts
| 700–800
| Closed
| 250, 1000
|[[Seaborg Technologies]], [[TerraPower]], [[Stable Salt Reactor|Moltex Energy]], [[Flibe Energy]] ([[Liquid fluoride thorium reactor|LFTR]]), [[Transatomic Power]], Thorium Tech Solution ([[Fuji Molten Salt Reactor|FUJI MSR]]), Terrestrial Energy ([[IMSR]]), [[Southern Company Services|Southern Company]]<ref name="energy.gov"/>, [[Elysium Industries]]<ref>http://www.elysiumindustries.com/</ref>
|-
| [[Dual fluid reactor|DFR]]
| Fast
| Lead
| 1000
| Closed
| 500–1500
| Institute for Solid-State Nuclear Physics<ref name=ifk>{{cite web |url=https://festkoerper-kernphysik.de/dfr.pdf |title=Dual Fluid Reactor - IFK |date=2013-06-16 |website=festkoerper-kernphysik.de |publisher= Institut für Festkörper-Kernphysik |format=PDF |location=Berlin, Germany |access-date=2017-08-28}}</ref>, [[Aristos Power]] <ref name=HSR>{{|url=http://aristospower.tk |title=Hard Spectrum Reactor - HSR</ref>
|}

== See also ==
{{portal|Energy|Nuclear technology}}
{{colbegin}}
* [[Nuclear reactor]]
* [[Nuclear material]]
* [[Nuclear physics]]
* [[List of reactor types#Reactor types|List of reactor types]]
* [[Generation II reactor]]
* [[Generation III reactor]]
* [[Integral Fast Reactor]]
* [[Liquid fluoride thorium reactor]]
* [[Breeder reactor]]
* [[Small modular reactor]]
{{colend}}

==References==
{{Reflist|30em}}

== External links ==
* [https://inlportal.inl.gov/portal/server.pt?open=514&objID=1361&parentname=CommunityPage&parentid=10&mode=2&in_hi_userid=200&cached=true Article from Idaho National Laboratory detailing some current efforts at developing Gen. IV reactors.]
* [http://www.gen-4.org/ Generation IV International Forum (GIF)]
* [https://web.archive.org/web/20070205115654/http://nuclear.energy.gov/genIV/neGenIV1.html U.S. Department of Energy Office of Nuclear Energy, Science and Technology]
* [https://web.archive.org/web/20060512033030/http://www.engr.utk.edu/nuclear/colloquia/slides/Gen%20IV%20U-Tenn%20Presentation.pdf Gen IV presentation]
* [http://www.ecology.at/ecology/files/pr577_1.pdf Science or Fiction - Is there a Future for Nuclear?] (Nov. 2007) - A publication from the Austrian [[Ecology Institute (Austria)|Ecology Institute]] about 'Generation IV' and Fusion reactors.
* {{cite web |url=http://memagazine.asme.org/Articles/2011/December/Nuclear_Power_After_Fukushima.cfm |title=Nuclear Power After Fukushima |author=Gail H. Marcus |date=December 2011 |work=Mechanical Engineering (the magazine of [[ASME]]) |accessdate=23 January 2012}} "In the wake of a severe plant accident, advanced reactor designs are getting renewed attention."
* [http://www.itheo.org/ International Thorium Energy Organisation - www.IThEO.org]
* [http://www.ithec.org/ International Thorium Energy Committee - iThEC]

{{Nuclear fission reactors}}

[[Category:Nuclear power reactor types]]
[[Category:Idaho National Laboratory]]

Benutzer:Snackroeg/Kernreaktoren der Generation 5

2018-04-15T20:22:18Z

Boundarylayer:

{{update|date=October 2017}}
[[File:GenIVRoadmap-en.svg|thumb|480px|Nuclear Energy Systems Deployable no later than 2030 and offering significant advances in sustainability, safety and reliability, and economics]]

'''Generation IV reactors''' ('''Gen IV''') are a set of [[nuclear reactor]] designs currently being researched for commercial applications by the Generation IV International Forum, with [[Technology readiness level]]s varying between the level requiring a demonstration, to economical competitive implementation.<ref>{{Cite journal|last=Locatelli|first=Giorgio|last2=Mancini|first2=Mauro|last3=Todeschini|first3=Nicola|date=2013-10-01|title=Generation IV nuclear reactors: Current status and future prospects|url=http://www.sciencedirect.com/science/article/pii/S0301421513006083|journal=Energy Policy|volume=61|pages=1503–1520|doi=10.1016/j.enpol.2013.06.101}}</ref> They are motivated by a variety of goals including improved safety, sustainability, efficiency, and cost.

The most developed Gen IV reactor design, the [[sodium fast reactor]], has received the greatest share of funding over the years, with the principle Gen IV aspect of the design, relating in largest part to the development of a sustainable [[Integral_fast_reactor#Fuel_cycle|closed fuel cycle]] for the reactor. Amongst nuclear engineers the [[molten-salt reactor]], the least developed and funded technology, is considered as potentially having the greatest [[inherent safety]] of the six models.<ref>[https://www.scientificamerican.com/article/can-sodium-save-nuclear-power/ Can Sodium Save Nuclear Power? Scientific American]</ref><ref>{{cite journal |last1=Moir |first1=Ralph |last2=Teller |first2=Edward |year=2005 |title=Thorium-Fueled Underground Power Plant Based on Molten Salt Technology |journal=Nuclear Technology |volume=151 |issue=3 |pages=334–340 |publisher=[[American Nuclear Society]] |url=http://www.new.ans.org/pubs/journals/nt/a_3655 |accessdate=March 22, 2012 }}</ref> While the [[hydrogen economy]], the use of hydrogen to produce [[Carbon-neutral fuel]]s, is deemed as strengthening the economic case for the two most efficient models, the [[Very-high-temperature reactor|high temperature reactor]] designs.<ref>[https://www.sciencedirect.com/science/article/pii/S0301421513006083 Generation IV nuclear reactors: Current status and future prospects doi.org/10.1016/j.enpol.2013.06.101]</ref>

The majority of the 6 designs are generally not expected to be available for commercial construction until 2020–30.<ref name="Generation IV">[http://www.world-nuclear.org/info/Nuclear-Fuel-Cycle/Power-Reactors/Generation-IV-Nuclear-Reactors/]</ref> Presently the majority of reactors in operation around the world are considered [[Generation II reactor|second generation reactor]] systems, as the vast majority of the [[Nuclear reactor#Classification by generation|first generation]] systems were retired some time ago, and there are only a dozen or so [[Generation III reactor]]s in operation as of 2014.
[[Nuclear reactor#Generation V+ reactors|Generation V reactors]] refer to reactors that are purely theoretical and are therefore not yet considered feasible in the short term, resulting in limited [[R&D]] funding.

== History ==
The Generation IV International Forum (GIF) is "a co-operative international endeavour which was set up to carry out the research and development needed to establish the feasibility and performance capabilities of the next generation nuclear energy systems."<ref>{{Cite web|url=https://www.gen-4.org/gif/jcms/c_9260/public|title=GIF Portal - Home - Public|website=www.gen-4.org|access-date=2016-07-25}}</ref> It was founded in 2001. Currently active members of the Generation IV International Forum (GIF) include: [[Australia]], [[Canada]], [[China]], the [[European Atomic Energy Community]] (Euratom), [[France]], [[Japan]], [[Russia]], [[South Africa]], [[South Korea]], [[Switzerland]], and the [[United States]]. The non-active members are [[Argentina]], [[Brazil]], and the [[United Kingdom]].<ref name="gen-4">{{cite web|url=https://www.gen-4.org/gif/jcms/c_9492/members|title=GIF Membership|website=gen-4.org|accessdate=28 October 2014}}</ref> Switzerland joined in 2002, Euratom in 2003, and China and Russia in 2006. The remaining countries (excluding Australia) were founding members.<ref name="gen-4" />

The 36th GIF meeting in [[Brussels]] was held in November 2013.<ref>{{cite web|url=https://www.energy.gov/ne/articles/generation-iv-international-forum-updates-technology-roadmap-and-builds-future|title=generation IV international forum updates technology roadmap and builds future. DOE}}</ref><ref>{{cite web|url=http://events.r20.constantcontact.com/register/event?llr=mscrkjkab&oeidk=a07e7melf609716b2c6 |title=The Generation IV international forum holds their 36th meeting on Monday 18th Nov 2013 in Brussels. }}{{dead link|date=January 2017 |bot=InternetArchiveBot |fix-attempted=yes }}</ref> The ''Technology Roadmap Update for Generation IV Nuclear Energy Systems'' was published in January 2014 which details R&D objectives for the next decade.<ref>[https://web.archive.org/web/20140625102915/https://www.gen-4.org/gif/upload/docs/application/pdf/2014-03/gif-tru2014.pdf Technology Roadmap Update for Generation IV Nuclear Energy Systems]</ref> A breakdown of the reactor designs being researched by each forum member has been made available.<ref>[https://web.archive.org/web/20140708023538/https://www.gen-4.org/gif/upload/docs/application/pdf/2014-03/gif_overview_presentation_v9_final3_web.pdf Generation IV International Forum, overview, John E. Kelly, page 15]</ref>

[[Nuclear power in Australia|Australia]] joined the forum in 2016.<ref>https://archive.is/20160907131656/https://www.gen-4.org/gif/jcms/c_71564/australia-joins-the-generation-iv-international-forum</ref>

In January 2018, it was reported that "the first installation of the pressure vessel cover of the world's first Gen IV reactor" had been completed on the [[HTR-PM]].<ref>http://www.world-nuclear-news.org/NN-First-HTR-PM-vessel-head-in-place-0401185.html</ref>

== Reactor types ==
Many reactor types were considered initially; however, the list was downsized to focus on the most promising technologies and those that could most likely meet the goals of the Gen IV initiative.<ref name="Generation IV"/> Three systems are nominally [[thermal reactor]]s and four are [[fast reactor]]s. The Very High Temperature Reactor (VHTR) is also being researched for potentially providing high quality process heat for [[thermochemical cycle|hydrogen production]]. The fast reactors offer the possibility of burning [[actinides]] to further reduce waste and of being able to "[[breeder reactor|breed more fuel]]" than they consume. These systems offer significant advances in sustainability, safety and reliability, economics, proliferation resistance (depending on perspective) and physical protection.

=== Thermal reactors ===
A [[Thermal-neutron reactor|thermal reactor]] is a [[nuclear reactor]] that uses slow or [[thermal neutrons]]. A [[neutron moderator]] is used to slow the [[neutron]]s emitted by fission to make them more likely to be captured by the fuel.

==== Very-high-temperature reactor (VHTR) ====
[[File:Very High Temperature Reactor.svg|right|thumb|Very-High-Temperature Reactor (VHTR)]]
{{Main article|Very high temperature reactor}}
{{see also|Fort St. Vrain Generating Station|High-temperature engineering test reactor|HTR-10}}
The '''very high temperature reactor''' concept uses a [[graphite]]-moderated core with a once-through [[uranium]] fuel cycle, using helium or molten salt as the [[Very high temperature reactor#Coolant|coolant]]. This reactor design envisions an outlet temperature of 1,000 °C. The reactor core can be either a prismatic-block or a [[pebble bed reactor]] design. The high temperatures enable applications such as process heat or [[hydrogen]] production via the thermochemical [[Sulfur-iodine cycle|iodine-sulfur]] process. It would also be [[Passive nuclear safety|passively safe]].

The planned construction of the first VHTR, the South African PBMR ([[pebble bed modular reactor]]), lost government funding in February, 2010.<ref>[http://www.powergenworldwide.com/index/display/articledisplay/6322207443/articles/power-engineering-international/volume-18/Issue_3/regulars/world-news/INTERNATIONAL.html South Africa to stop funding Pebble Bed nuclear reactor] {{webarchive|url=https://web.archive.org/web/20100909172743/http://www.powergenworldwide.com/index/display/articledisplay/6322207443/articles/power-engineering-international/volume-18/Issue_3/regulars/world-news/INTERNATIONAL.html |date=2010-09-09 }}</ref> A pronounced increase of costs and concerns about possible unexpected technical problems had discouraged potential investors and customers.

The [[Peoples Republic of China]] began construction of a 200-MW High Temperature Pebble bed reactor in 2012 as a successor to its [[HTR-10]].<ref>[http://www.nucnet.org/all-the-news/2013/01/07/china-begins-construction-of-first-generation-iv-htr-pm-unit Nucnet Report: 'China Begins Construction of First Generation IV HTR-PM Unit', 7 January 2013]</ref>

Also in 2012, as part of the [[Next Generation Nuclear Plant]] competition, [[Idaho National Laboratory]] approved a design similar to [[Areva]]'s prismatic block [http://us.areva.com/EN/home-3225/areva-inc-areva-htgr.html Antares reactor] as the chosen [[HTGR]] to be deployed as a prototype by 2021. It was in competition with [[General Atomics]]' [[Gas turbine modular helium reactor]] and [[Westinghouse Electric Company|Westinghouse]]'s [[Pebble Bed Modular Reactor]].<ref name="World nuclear news">{{cite web|url=http://www.world-nuclear-news.org/NN-Areva_modular_reactor_selected_for_NGNP_development-1502124.html|title=INL approves Antares design}}</ref>

[[X-energy]] was awarded a five-year $53M U.S. Department of Energy Advanced Reactor Concept Cooperative Agreement award to advance elements of their reactor development.<ref>[https://www.x-energy.com/doe-partnership]</ref>
The [[X-energy#Reactor Design|Xe-100]] is a pebble-bed modular reactor and will generate 200-MWt and approximately 76-MWe. The standard Xe-100 "four-pack" plant generates approximately 300-MWe and will fit on as few as 13 acres. All of the components for the Xe-100 will be road-transportable, and will be installed, rather than constructed, at the project site to streamline construction.<ref name="X-energy">{{cite web|url=https://www.x-energy.com/}}</ref>

==== Molten-salt reactor (MSR) ====
[[File:Molten Salt Reactor.svg|right|thumb|Molten Salt Reactor (MSR)]]
{{Main article|Molten salt reactor}}
{{see also|Liquid fluoride thorium reactor}}
A '''molten salt reactor'''<ref name="Roadmap"/> is a type of [[nuclear reactor]] where the primary [[coolant]], or even the fuel itself is a molten salt mixture. There have been many designs put forward for this type of reactor and a few prototypes built. The early concepts and many current ones rely on [[nuclear fuel]], perhaps [[uranium tetrafluoride]] (UF4) or [[thorium tetrafluoride]] (ThF4), dissolved in molten [[fluoride]] salt. The fluid would reach [[Nuclear reactor physics#Criticality|criticality]] by flowing into a core where [[graphite]] would serve as the [[neutron moderator|moderator]]. Many current concepts rely on fuel that is dispersed in a graphite matrix with the molten salt providing low pressure, high temperature cooling.

The Gen IV MSR is more accurately termed an [[epithermal neutron|epithermal reactor]] than a thermal reactor due to the average speed of the neutrons that would cause the fission events within its fuel being faster than [[thermal neutron]]s.<ref>{{cite web |url=https://inlportal.inl.gov/portal/server.pt?open=514&objID=1361&parentname=CommunityPage&parentid=10&mode=2&in_hi_userid=200&cached=true |title=Idaho National Laboratory detailing some current efforts at developing Gen. IV reactors}}</ref>

The principle of a MSR can be used for thermal, epithermal and fast reactors. Since 2005 the focus has moved towards a fast spectrum MSR (MSFR).<ref>H. Boussier, S. Delpech, V. Ghetta et Al. : The Molten Salt Reactor (MSR) in Generation IV: Overview and Perspectives, GIF SYMPOSIUM PROCEEDINGS/2012 ANNUAL REPORT, NEA No. 7141, pp95 [https://www.gen-4.org/gif/jcms/c_44720/annual-reports]
</ref>

While most MSR designs being pursued are largely derived from the 1960s [[Molten-Salt Reactor Experiment]] (MSRE), variants of molten salt technology include the conceptual ''[[Dual fluid reactor]]'' which is being designed with lead as a cooling medium but molten salt fuel, commonly as the metal chloride e.g. [[Plutonium(III) chloride]], to aid in greater "nuclear waste" closed-fuel cycle capabilities.
Other notable approaches differing substantially from MSRE include the ''[[Stable Salt Reactor]]''(SSR) concept promoted by MOLTEX, which encases the molten salt in hundreds of the common solid [[fuel rod]]s that are already well established in the nuclear industry. This latter British design was found to be the most competitive for [[Small modular reactor]] development by a British-based consultancy firm ''Energy Process Development'' in 2015.<ref>[http://www.daretothink.org/europe-moltex-stable-salt-reactor/ Europe: Moltex’ Stable Salt Reactor]</ref><ref>[http://analysis.nuclearenergyinsider.com/moltex-energy-sees-uk-canada-smr-licensing-springboard-asia Moltex Energy sees UK, Canada SMR licensing as springboard to Asia Jun 28, 2016]</ref>

Another notable feature of the MSR is the possibility of a [[Thermal-neutron reactor|thermal spectrum]] nuclear [[Nuclear fuel cycle#Fuel cycles|waste-burner]]. Conventionally only fast spectrum reactors have been considered viable for [[Nuclear fuel cycle#Minor actinides recycling|utilization or reduction]] of the [[Spent nuclear fuel|spent nuclear stockpiles]]. The conceptual viability of a thermal waste-burner was first shown in a whitepaper by [[Seaborg Technologies]] spring 2015.<ref name="Seaborg Whitepaper 2015">{{cite web|url=https://seaborg.dk/s/Seaborg-whitepaper-2015.pdf|title=Thermal MSR waste burner benchmark}}</ref> Thermal waste-burning was achieved by replacing a fraction of the [[uranium]] in the spent nuclear fuel with [[thorium]]. The net production rate of [[transuranium element]] (e.g. [[plutonium]] and [[americium]]) is reduced below the consumption rate, thus reducing the magnitude of the [[Radioactive waste|nuclear storage problem]]. Without the [[nuclear proliferation]] concerns and other [[Fast-neutron reactor#Disadvantages|technical issues]] associated with a [[Fast-neutron reactor|fast reactor]].

==== Supercritical-water-cooled reactor (SCWR) ====
[[File:Supercritical-Water-Cooled Reactor.svg|right|thumb|Supercritical-Water-Cooled Reactor (SCWR)]]
{{Main article|Supercritical water reactor}}
The '''supercritical water reactor''' (SCWR)<ref name="Roadmap"/> is a [[reduced moderation water reactor]] concept that, due to the average speed of the neutrons that would cause the fission events within the fuel being faster than [[thermal neutron]]s, it is more accurately termed an [[epithermal neutron|epithermal reactor]] than a thermal reactor. It uses [[supercritical fluid|supercritical water]] as the working fluid. SCWRs are basically [[light water reactor]]s (LWR) operating at higher pressure and temperatures with a direct, once-through heat exchange cycle. As most commonly envisioned, it would operate on a direct cycle, much like a boiling water reactor ([[BWR]]), but since it uses supercritical water (not to be confused with [[Critical mass (nuclear)|critical mass]]) as the working fluid, it would have only one water phase present, which makes the supercritical heat exchange method more similar to a pressurized water reactor ([[Pressurized water reactor|PWR]]). It could operate at much higher temperatures than both current PWRs and BWRs.

Supercritical water-cooled reactors (SCWRs) are promising advanced nuclear systems because of their high [[thermal efficiency]] (i.e., about 45% vs. about 33% efficiency for current LWRs) and considerable plant simplification.

The main mission of the SCWR is generation of low-cost [[electricity]]. It is built upon two proven technologies, LWRs, which are the most commonly deployed power generating reactors in the world, and superheated [[fossil fuel]] fired [[boiler]]s, a large number of which are also in use around the world. The SCWR concept is being investigated by 32 organizations in 13 countries.{{citation needed|date=October 2012}}

Because SCWRs are water reactors they share the steam explosion and radioactive steam release hazards of BWRs and LWRs as well as the need for extremely expensive heavy duty pressure vessels, pipes, valves, and pumps. These shared problems are inherently more severe for SCWRs due to operation at higher temperatures.

A SCWR Design under development is the [[VVER]]-1700/393 (VVER-SCWR or VVER-SKD) — a Russian Supercritical-water-cooled reactor with double-inlet-core and a [[breeder reactor|breeding ratio]] of 0.95.<ref name="powertecrussia.com">{{cite web |url=http://www.powertecrussia.com/blog/tag/nuclear-power/ |title=Technology Developments & Plant Efficiency for the Russian Nuclear Power Generation Market Wednesday |date=March 24, 2010}}</ref>

=== Fast reactors ===
A [[Fast-neutron reactor|fast reactor]] directly uses the fast neutrons emitted by fission, without moderation. Unlike thermal neutron reactors, fast neutron reactors can be configured to "'''burn'''", or fission, all [[actinides]], and given enough time, therefore drastically reduce the actinides fraction in [[spent nuclear fuel]] produced by the present world fleet of thermal neutron [[light water reactor]]s, thus closing the [[nuclear fuel cycle]]. Alternatively, if configured differently, they can also [[breeder reactor|'''breed''']] more actinide fuel than they consume.

==== Gas-cooled fast reactor (GFR) ====
[[File:Gas-Cooled Fast Reactor Schemata.svg|right|thumb|Gas-Cooled Fast Reactor (GFR)]]
{{Main article|Gas-cooled fast reactor}}
The '''gas-cooled fast reactor''' (GFR)<ref name="Roadmap"/> system features a fast-neutron spectrum and closed fuel cycle for efficient conversion of [[Fertile material|fertile uranium]] and management of actinides. The reactor is [[helium]]-cooled and with an outlet temperature of 850 °C it is an evolution of the [[very-high-temperature reactor]] (VHTR) to a more sustainable fuel cycle. It will use a direct [[Brayton cycle]] [[Closed-cycle gas turbine|gas turbine]] for high thermal efficiency. Several fuel forms are being considered for their potential to operate at very high temperatures and to ensure an excellent retention of [[Nuclear fission|fission]] products: composite [[ceramic]] fuel, advanced fuel particles, or ceramic clad elements of actinide compounds. Core configurations are being considered based on pin- or plate-based fuel assemblies or prismatic blocks.

The European Sustainable Nuclear Industrial Initiative is funding three Generation IV reactor systems, one of which is a gas-cooled fast reactor, called ''Allegro'', 100 MW(t), which will be built in a central or eastern European country with construction expected to begin in 2018.<ref name="euronuclear.org">{{cite web|url=https://www.euronuclear.org/1-information/news/Gen-IV.htm |title=The European Sustainable Nuclear Industrial Initiative (ESNII) will support three Generation IV reactor systems: a sodium-cooled fast reactor, or SFR, called ''Astrid'' that is proposed by France; a gas-cooled fast reactor, GFR, called ''Allegro'' supported by central and eastern Europe; and a lead-cooled fast reactor, LFR, technology pilot called ''Myrrha'' that is proposed by Belgium. |deadurl=yes |archiveurl=https://web.archive.org/web/20131009042600/http://euronuclear.org/1-information/news/Gen-IV.htm |archivedate=2013-10-09 |df= }}</ref> The central European [[Visegrád Group]] are committed to pursuing the technology.<ref>{{cite web |url=http://www.alphagalileo.org/ViewItem.aspx?ItemId=133111&CultureCode=en |title=The V4G4 Centre of Excellence for performing joint research, development and innovation in the field of Generation-4 (G4) nuclear reactors have been established. 20 July 2013 National Center for Nuclear Research (NCBJ)}}</ref> In 2013 German, British, and French institutes finished a 3-year collaboration study on the follow on industrial scale design, known as ''GoFastR''.<ref>{{cite web|url=http://www.ist-world.org/ProjectDetails.aspx?ProjectId=5cb8f3f283574cc6b2bdbf72533172d8 |title=the European Gas cooled Fast Reactor. |deadurl=yes |archiveurl=https://web.archive.org/web/20131213091046/http://www.ist-world.org/ProjectDetails.aspx?ProjectId=5cb8f3f283574cc6b2bdbf72533172d8 |archivedate=2013-12-13 |df= }}</ref> They were funded by the EU's 7th FWP [[framework programme]], with the goal of making a sustainable VHTR.<ref>{{cite web |url=http://www.2020-horizon.com/GOFASTR-European-Gas-Cooled-Fast-Reactor%28GOFASTR%29-s312.html |title=The GOFASTR research program}}</ref>

==== Sodium-cooled fast reactor (SFR) ====
[[File:Sodium-Cooled Fast Reactor Schemata.svg|right|thumb|Pool design Sodium-Cooled Fast Reactor (SFR)]]
{{Main article|Sodium-cooled fast reactor}}
{{see also|Prototype Fast Breeder Reactor|Experimental Breeder Reactor II|S-PRISM|BN-800 reactor|Toshiba 4S|CFR-600}}

In India, the [[Fast Breeder Test Reactor]] reached criticality in October 1985. In September 2002, fuel burn-up in the FBTR for the first time reached the 100,000 megawatt-days per metric ton uranium (MWd/MTU) mark. This is considered an important milestone in breeder reactor technology. Using the experience gained from the operation of the FBTR, the [[Prototype Fast Breeder Reactor]], a 500 MWe Sodium cooled fast reactor is being built at a cost of INR 5,677 crores (~US$900 million) and is expected to be critical by June 2018. The PFBR will be followed by six more Commercial Fast Breeder Reactors (CFBRs) of 600 MWe each.

The SFR<ref name="Roadmap"/> is a project that builds on two closely related existing projects, the liquid metal [[Breeder reactor#Fast breeder reactor|fast breeder reactor]] and the [[integral fast reactor]].

The goals are to increase the efficiency of uranium usage by [[breeder reactor|breeding]] plutonium and eliminating the need for [[transuranic]] isotopes ever to leave the site. The reactor design uses an unmoderated core running on [[fast neutron]]s, designed to allow any transuranic isotope to be consumed (and in some cases used as fuel). In addition to the benefits of removing the long [[half-life]] transuranics from the waste cycle, the SFR fuel expands when the reactor overheats, and the chain reaction automatically slows down. In this manner, it is passively safe.<ref>{{cite web |url=http://www.ne.anl.gov/About/hn/logos-winter02-psr.shtml|title=Passively safe reactors rely on nature to keep them cool|author=David Baurac}}</ref>

The SFR reactor concept is cooled by liquid [[sodium]] and fueled by a metallic alloy of uranium and [[plutonium]] or [[spent nuclear fuel]], the "nuclear waste" of [[light water reactor]]s. The SFR fuel is contained in steel cladding with liquid sodium filling in the space between the clad elements which make up the fuel assembly. One of the design challenges of an SFR is the risks of handling sodium, which reacts explosively if it comes into contact with water. However, the use of liquid metal instead of water as coolant allows the system to work at atmospheric pressure, reducing the risk of leakage.

The European Sustainable Nuclear Industrial Initiative is funding three Generation IV reactor systems, one of which is a sodium-cooled fast reactor, called ''[[ASTRID (reactor)|ASTRID]]'', Advanced Sodium Technical Reactor for Industrial Demonstration, [[Areva]], [[Commissariat à l'énergie atomique et aux énergies alternatives|CEA]] and [[Électricité de France|EDF]] are leading the design with British collaboration.<ref>{{cite web |url=http://www.power-eng.com/articles/2010/11/areva--cea-secure.html |title=Areva, CEA secure EUR650m funding to develop ASTRID sodium-cooled Generation IV reactor 11/11/2010}}</ref><ref>{{cite web |url=http://www.powermag.com/uk-and-france-sign-landmark-civil-nuclear-cooperation-agreement/ |title=UK and France Sign Landmark Civil Nuclear Cooperation Agreement 02/22/2012 . POWERnews}}</ref> Astrid will be rated about 600 MWe and is proposed to be built in France, near to the [[Phénix]] reactor. A final decision in construction is to be made in 2019<ref name="euronuclear.org"/>

The [[China|PRC]]'s first commercial-scale, 800 MWe, fast neutron reactor, to be situated near [[Sanming]] in [[Fujian province]] will be a SFR. In 2009 an agreement was signed that would entail the Russian [[BN-800 reactor]] design to be sold to the PRC once it is completed, this would be the first time commercial-scale fast neutron reactors have ever been exported.<ref>{{cite web |url=http://www.world-nuclear-news.org/C-Joint_venture_launched_for_Chinese_fast_reactor-3004104.html |title=Joint venture launched for Chinese fast reactor}}</ref> The BN-800 reactor became operational in 2014.

The 400 MWe [[Fast Flux Test Facility]] operated successfully for ten years at the Hanford site in Washington State.

The 20 MWe [[EBR II]] operated successfully for over thirty years at the Idaho National Laboratory, until it was shut down in 1994.

GE Hitachi's [[PRISM (reactor)|PRISM]] reactor is an SFR with the primary purpose of reducing the half lives of the fissionable elements present in used nuclear fuel while generating electricity largely as a by-product.

==== Lead-cooled fast reactor (LFR) ====
[[File:Lead-Cooled Fast Reactor Schemata.svg|right|thumb|Lead-Cooled Fast Reactor (LFR)]]
{{Main article|Lead-cooled fast reactor}}
{{See also|MYRRHA}}
The '''lead-cooled fast reactor'''<ref name="Roadmap">{{cite journal|year=2002 |title=A Technology Roadmap for Generation IV Nuclear Energy Systems |last=US DOE Nuclear Energy Research Advisory Committee |volume=GIF-002-00 |url=http://nuclear.energy.gov/genIV/documents/gen_iv_roadmap.pdf |deadurl=yes |archiveurl=https://web.archive.org/web/20071129121214/http://nuclear.energy.gov/genIV/documents/gen_iv_roadmap.pdf |archivedate=2007-11-29 |df= }}</ref> features a fast-neutron-spectrum [[lead]] or [[lead]]/[[bismuth]] [[eutectic]] ([[Lead-bismuth eutectic|LBE]]) liquid-metal-cooled reactor with a closed [[Nuclear fuel cycle|fuel cycle]]. Options include a range of plant ratings, including a "battery" of 50 to 150 MW of electricity that features a very long refueling interval, a modular system rated at 300 to 400 MW, and a large monolithic plant option at 1,200 MW (The term ''battery'' refers to the long-life, factory-fabricated core, not to any provision for electrochemical energy conversion). The fuel is metal or nitride-based containing [[Fertile material|fertile uranium]] and [[transuranic]]s. The LFR is cooled by natural [[convection]] with a reactor outlet coolant temperature of 550 °C, possibly ranging up to 800 °C with advanced materials. The higher temperature enables the production of [[Thermochemical cycle|hydrogen by thermochemical processes]].

The European Sustainable Nuclear Industrial Initiative is funding three Generation IV reactor systems, one of which is a lead-cooled fast reactor that is also an [[Subcritical reactor|accelerator-driven sub-critical]] reactor, called ''[[MYRRHA]]'', 100 MW(t), which will be built in [[Belgium]] with construction expected to begin after 2014 and the industrial scale version, known as ''Alfred'', slated to be constructed sometime after 2017. A reduced-power model of Myrrha called ''Guinevere'' was started up at [[Mol, Belgium|Mol]] in March 2009.<ref name="euronuclear.org"/> In 2012 the research team reported that Guinevere was operational.<ref>{{cite news|last1=Hellemans|first1=Alexander|title=Reactor-Accelerator Hybrid Achieves Successful Test Run|url=http://news.sciencemag.org/physics/2012/01/reactor-accelerator-hybrid-achieves-successful-test-run|accessdate=29 December 2014|work=Science Insider|date=12 January 2012}}</ref>

Two other lead-cooled fast reactors under development are the SVBR-100, a modular 100 MWe lead-bismuth cooled fast neutron reactor concept designed by OKB [[Gidropress]] in Russia and the [[BREST (Reactor)|BREST-OD-300]] (Lead-cooled fast reactor) 300 MWe, to be developed after the SVBR-100, and built over 2016-20, it will dispense with the [[Uranium-238|fertile blanket]] around the core and will supersede the sodium cooled [[BN-600 reactor]] design, to purportedly give enhanced proliferation resistance.<ref name="powertecrussia.com"/>

== Advantages and disadvantages ==
Relative to current nuclear power plant technology, the claimed benefits for 4th generation reactors include:
* Nuclear waste that remains radioactive for a few centuries instead of millennia<ref>{{cite web |title=Strategies to Address Global Warming |url=http://www.columbia.edu/~jeh1/mailings/2009/20090713_Strategies.pdf}}</ref>
* 100–300 times more energy yield from the same amount of nuclear fuel<ref>{{cite web |title=4th Generation Nuclear Power |url=http://www.ossfoundation.us/projects/energy/nuclear}}</ref>
* Broader range of fuels, and even unencapsulated raw fuels (non-pebble [[Molten Salt Reactor|MSR]], [[Liquid fluoride thorium reactor|LFTR]]).
* In some reactors, the ability to consume existing nuclear waste in the production of electricity, that is, a Closed [[nuclear fuel cycle]]. This strengthens the argument to deem [[nuclear power as renewable energy]].
* Improved operating safety features, such as (depending on design) avoidance of pressurized operation, automatic passive (unpowered, uncommanded) reactor shutdown, avoidance of water cooling and the associated risks of loss of water (leaks or boiling) and hydrogen generation/explosion and contamination of coolant water.

Nuclear reactors do not emit CO2 during operation, although like all [[low carbon power]] sources, the mining and construction phase can result in CO2 emissions, if energy sources which are not carbon neutral (such as fossil fuels), or CO2 emitting cements are used during the construction process.
A 2012 [[Yale University]] review published in the Journal of Industrial Ecology analyzing {{CO2}} [[life cycle assessment]] (LCA) emissions from [[nuclear power]] determined that:<ref name="Warner + Heath, JoIE">Warner, Ethan S.; Heath, Garvin A. [http://onlinelibrary.wiley.com/doi/10.1111/j.1530-9290.2012.00472.x/full Life Cycle Greenhouse Gas Emissions of Nuclear Electricity Generation: Systematic Review and Harmonization], ''Journal of Industrial Ecology'', [[Yale University]], published online April 17, 2012, {{doi|10.1111/j.1530-9290.2012.00472.x}}</ref>
{{Quote|The collective LCA literature indicates that life cycle [[Greenhouse gas|GHG]] [greenhouse gas] emissions from nuclear power are only a fraction of traditional fossil sources and comparable to renewable technologies.}}
Although the paper primarily dealt with data from [[Generation II reactor]]s, and did not analyze the {{CO2}} emissions by 2050 of the presently under construction [[Generation III reactor]]s, it did summarize the Life Cycle Assessment findings of in development reactor technologies.{{Quote|FBRs ['[[Fast Breeder Reactor]]s'] have been evaluated in the LCA literature. The limited literature that evaluates this potential future technology reports [[median]] life cycle GHG emissions... similar to or lower than LWRs [Gen II [[light water reactor]]s] and purports to consume little or no [[uranium market|uranium ore]].}}

A specific risk of the sodium-cooled fast reactor is related to using metallic sodium as a coolant. In case of a breach, sodium explosively reacts with water. Fixing breaches may also prove dangerous, as the cheapest noble gas [[argon]] is also used to prevent sodium oxidation. Argon, like helium, can displace oxygen in the air and can pose [[hypoxia (environmental)|hypoxia]] concerns, so workers may be exposed to this additional risk. This is a pertinent problem as demonstrated by the events at the [[LMFBR|loop type]] [[Monju Nuclear Power Plant|Prototype Fast Breeder Reactor Monju]] at Tsuruga, Japan.<ref>{{cite news |title=Japan Strains to Fix a Reactor Damaged Before Quake |url=https://www.nytimes.com/2011/06/18/world/asia/18japan.html | work=The New York Times | first=Hiroko |last=Tabuchi |date=17 June 2011}}</ref>
Using lead or molten salts mitigates this problem by making the coolant less reactive and allowing a high freezing temperature and low pressure in case of a leak. Disadvantages of lead compared to sodium are much higher viscosity, much higher density, lower heat capacity, and more radioactive neutron activation products.

In many cases, there is already a large amount of experience built up with numerous proof of concept Gen IV designs. For example, the reactors at [[Fort St. Vrain Generating Station]] and [[HTR-10]] are similar to the proposed Gen IV [[VHTR]] designs, and the [[LMFBR|pool type]] [[EBR-II]], [[Phénix]] and [[BN-600]] reactor are similar to the proposed pool type Gen IV Sodium Cooled Fast reactors being designed.

== Table of designs ==

{| class=wikitable
|+ Summary of designs for generation IV reactors<ref>https://www.gen-4.org/gif/upload/docs/application/pdf/2013-09/gif_rd_outlook_for_generation_iv_nuclear_energy_systems.pdf</ref>
|-
! System
! Neutron Spectrum
! Coolant
! Temperature (°C)
! Fuel Cycle
! Size (MW)
!Example developers
|-
| [[Very-high-temperature reactor|VHTR]]
| Thermal
| Helium
| 900–1000
| Open
| 250–300
|[[Japan Atomic Energy Agency|JAEA]] ([[High-temperature engineering test reactor|HTTR]]), [[Tsinghua University]] ([[HTR-10]]), [[X-energy]]<ref name="energy.gov">{{cite web|title=Energy Department Announces New Investments in Advanced Nuclear Power Reactors...|url=https://www.energy.gov/articles/energy-department-announces-new-investments-advanced-nuclear-power-reactors-help-meet|website=[[United States Department of Energy|US Department of Energy]]|accessdate=16 January 2016}}</ref>
|-
| [[Sodium-cooled fast reactor|SFR]]
| Fast
| Sodium
| 550
| Closed
| 30–150, 300–1500, 1000–2000
|[[TerraPower]] ([[Traveling wave reactor|TWR]]), [[Toshiba]] ([[Toshiba 4S|4S]]), [[GE Hitachi Nuclear Energy]] ([[PRISM (reactor)|PRISM]])
|-
| [[Supercritical water reactor|SCWR]]
| Thermal or fast
| Water
| 510–625
| Open or closed
| 300–700, 1000–1500
|
|-
| [[Gas-cooled fast reactor|GFR]]
| Fast
| Helium
| 850
| Closed
| 1200
|[[Energy Multiplier Module]]
|-
| [[Lead-cooled fast reactor|LFR]]
| Fast
| Lead
| 480–800
| Closed
| 20–180, 300–1200, 600–1000
|
|-
| [[Molten salt reactor|MSR]]
| Fast or thermal
| Fluoride or chloride salts
| 700–800
| Closed
| 250, 1000
|[[Seaborg Technologies]], [[TerraPower]], [[Stable Salt Reactor|Moltex Energy]], [[Flibe Energy]] ([[Liquid fluoride thorium reactor|LFTR]]), [[Transatomic Power]], Thorium Tech Solution ([[Fuji Molten Salt Reactor|FUJI MSR]]), Terrestrial Energy ([[IMSR]]), [[Southern Company Services|Southern Company]]<ref name="energy.gov"/>, [[Elysium Industries]]<ref>http://www.elysiumindustries.com/</ref>
|-
| [[Dual fluid reactor|DFR]]
| Fast
| Lead
| 1000
| Closed
| 500–1500
| Institute for Solid-State Nuclear Physics<ref name=ifk>{{cite web |url=https://festkoerper-kernphysik.de/dfr.pdf |title=Dual Fluid Reactor - IFK |date=2013-06-16 |website=festkoerper-kernphysik.de |publisher= Institut für Festkörper-Kernphysik |format=PDF |location=Berlin, Germany |access-date=2017-08-28}}</ref>, [[Aristos Power]] <ref name=HSR>{{|url=http://aristospower.tk |title=Hard Spectrum Reactor - HSR</ref>
|}

== See also ==
{{portal|Energy|Nuclear technology}}
{{colbegin}}
* [[Nuclear reactor]]
* [[Nuclear material]]
* [[Nuclear physics]]
* [[List of reactor types#Reactor types|List of reactor types]]
* [[Generation II reactor]]
* [[Generation III reactor]]
* [[Integral Fast Reactor]]
* [[Liquid fluoride thorium reactor]]
* [[Breeder reactor]]
* [[Small modular reactor]]
{{colend}}

==References==
{{Reflist|30em}}

== External links ==
* [https://inlportal.inl.gov/portal/server.pt?open=514&objID=1361&parentname=CommunityPage&parentid=10&mode=2&in_hi_userid=200&cached=true Article from Idaho National Laboratory detailing some current efforts at developing Gen. IV reactors.]
* [http://www.gen-4.org/ Generation IV International Forum (GIF)]
* [https://web.archive.org/web/20070205115654/http://nuclear.energy.gov/genIV/neGenIV1.html U.S. Department of Energy Office of Nuclear Energy, Science and Technology]
* [https://web.archive.org/web/20060512033030/http://www.engr.utk.edu/nuclear/colloquia/slides/Gen%20IV%20U-Tenn%20Presentation.pdf Gen IV presentation]
* [http://www.ecology.at/ecology/files/pr577_1.pdf Science or Fiction - Is there a Future for Nuclear?] (Nov. 2007) - A publication from the Austrian [[Ecology Institute (Austria)|Ecology Institute]] about 'Generation IV' and Fusion reactors.
* {{cite web |url=http://memagazine.asme.org/Articles/2011/December/Nuclear_Power_After_Fukushima.cfm |title=Nuclear Power After Fukushima |author=Gail H. Marcus |date=December 2011 |work=Mechanical Engineering (the magazine of [[ASME]]) |accessdate=23 January 2012}} "In the wake of a severe plant accident, advanced reactor designs are getting renewed attention."
* [http://www.itheo.org/ International Thorium Energy Organisation - www.IThEO.org]
* [http://www.ithec.org/ International Thorium Energy Committee - iThEC]

{{Nuclear fission reactors}}

[[Category:Nuclear power reactor types]]
[[Category:Idaho National Laboratory]]

Benutzer:Snackroeg/Kernreaktoren der Generation 5

2018-02-25T06:23:59Z

Boundarylayer:

{{update|date=October 2017}}
[[File:GenIVRoadmap-en.svg|thumb|480px|Nuclear Energy Systems Deployable no later than 2030 and offering significant advances in sustainability, safety and reliability, and economics]]

'''Generation IV reactors''' ('''Gen IV''') are a set of [[nuclear reactor]] designs currently being researched for commercial applications by the Generation IV International Forum, with [[Technology readiness level]]s varying between the level requiring a demonstration, to economical competitive implementation.<ref>{{Cite journal|last=Locatelli|first=Giorgio|last2=Mancini|first2=Mauro|last3=Todeschini|first3=Nicola|date=2013-10-01|title=Generation IV nuclear reactors: Current status and future prospects|url=http://www.sciencedirect.com/science/article/pii/S0301421513006083|journal=Energy Policy|volume=61|pages=1503–1520|doi=10.1016/j.enpol.2013.06.101}}</ref> They are motivated by a variety of goals including improved safety, sustainability, efficiency, and cost.

The most developed Gen IV reactor design, the [[sodium fast reactor]], has received the greatest share of funding over the years, with the principle Gen IV aspect of the design, relating in largest part to the development of a sustainable [[nuclear fuel cycle|closed fuel cycle]] for the reactor. Amongst nuclear engineers the [[molten-salt reactor]], the least developed and funded technology, is considered as potentially having the greatest [[inherent safety]] of the six models.<ref>[https://www.scientificamerican.com/article/can-sodium-save-nuclear-power/ Can Sodium Save Nuclear Power? Scientific American]</ref><ref>{{cite journal |last1=Moir |first1=Ralph |last2=Teller |first2=Edward |year=2005 |title=Thorium-Fueled Underground Power Plant Based on Molten Salt Technology |journal=Nuclear Technology |volume=151 |issue=3 |pages=334–340 |publisher=[[American Nuclear Society]] |url=http://www.new.ans.org/pubs/journals/nt/a_3655 |accessdate=March 22, 2012 }}</ref> While the [[hydrogen economy]], the use of hydrogen to produce [[Carbon-neutral fuel]]s, is deemed as strengthening the economic case for the two most efficient models, the [[Very-high-temperature reactor|high temperature reactor]] designs.<ref>[https://www.sciencedirect.com/science/article/pii/S0301421513006083 Generation IV nuclear reactors: Current status and future prospects doi.org/10.1016/j.enpol.2013.06.101]</ref>

The majority of the 6 designs are generally not expected to be available for commercial construction until 2020–30.<ref name="Generation IV">[http://www.world-nuclear.org/info/Nuclear-Fuel-Cycle/Power-Reactors/Generation-IV-Nuclear-Reactors/]</ref> Presently the majority of reactors in operation around the world are considered [[Generation II reactor|second generation reactor]] systems, as the vast majority of the [[Nuclear reactor#Classification by generation|first generation]] systems were retired some time ago, and there are only a dozen or so [[Generation III reactor]]s in operation as of 2014.
[[Nuclear reactor#Generation V+ reactors|Generation V reactors]] refer to reactors that are purely theoretical and are therefore not yet considered feasible in the short term, resulting in limited [[R&D]] funding.

== History ==
The Generation IV International Forum (GIF) is "a co-operative international endeavour which was set up to carry out the research and development needed to establish the feasibility and performance capabilities of the next generation nuclear energy systems."<ref>{{Cite web|url=https://www.gen-4.org/gif/jcms/c_9260/public|title=GIF Portal - Home - Public|website=www.gen-4.org|access-date=2016-07-25}}</ref> It was founded in 2001. Currently active members of the Generation IV International Forum (GIF) include: [[Australia]], [[Canada]], [[China]], the [[European Atomic Energy Community]] (Euratom), [[France]], [[Japan]], [[Russia]], [[South Africa]], [[South Korea]], [[Switzerland]], and the [[United States]]. The non-active members are [[Argentina]], [[Brazil]], and the [[United Kingdom]].<ref name="gen-4">{{cite web|url=https://www.gen-4.org/gif/jcms/c_9492/members|title=GIF Membership|website=gen-4.org|accessdate=28 October 2014}}</ref> Switzerland joined in 2002, Euratom in 2003, and China and Russia in 2006. The remaining countries (excluding Australia) were founding members.<ref name="gen-4" />

The 36th GIF meeting in [[Brussels]] was held in November 2013.<ref>{{cite web|url=https://www.energy.gov/ne/articles/generation-iv-international-forum-updates-technology-roadmap-and-builds-future|title=generation IV international forum updates technology roadmap and builds future. DOE}}</ref><ref>{{cite web|url=http://events.r20.constantcontact.com/register/event?llr=mscrkjkab&oeidk=a07e7melf609716b2c6 |title=The Generation IV international forum holds their 36th meeting on Monday 18th Nov 2013 in Brussels. }}{{dead link|date=January 2017 |bot=InternetArchiveBot |fix-attempted=yes }}</ref> The ''Technology Roadmap Update for Generation IV Nuclear Energy Systems'' was published in January 2014 which details R&D objectives for the next decade.<ref>[https://web.archive.org/web/20140625102915/https://www.gen-4.org/gif/upload/docs/application/pdf/2014-03/gif-tru2014.pdf Technology Roadmap Update for Generation IV Nuclear Energy Systems]</ref> A breakdown of the reactor designs being researched by each forum member has been made available.<ref>[https://web.archive.org/web/20140708023538/https://www.gen-4.org/gif/upload/docs/application/pdf/2014-03/gif_overview_presentation_v9_final3_web.pdf Generation IV International Forum, overview, John E. Kelly, page 15]</ref>

[[Nuclear power in Australia|Australia]] joined the forum in 2016.<ref>https://archive.is/20160907131656/https://www.gen-4.org/gif/jcms/c_71564/australia-joins-the-generation-iv-international-forum</ref>

In January 2018, it was reported that "the first installation of the pressure vessel cover of the world's first Gen IV reactor" had been completed on the [[HTR-PM]].<ref>http://www.world-nuclear-news.org/NN-First-HTR-PM-vessel-head-in-place-0401185.html</ref>

== Reactor types ==
Many reactor types were considered initially; however, the list was downsized to focus on the most promising technologies and those that could most likely meet the goals of the Gen IV initiative.<ref name="Generation IV"/> Three systems are nominally [[thermal reactor]]s and four are [[fast reactor]]s. The Very High Temperature Reactor (VHTR) is also being researched for potentially providing high quality process heat for [[thermochemical cycle|hydrogen production]]. The fast reactors offer the possibility of burning [[actinides]] to further reduce waste and of being able to "[[breeder reactor|breed more fuel]]" than they consume. These systems offer significant advances in sustainability, safety and reliability, economics, proliferation resistance (depending on perspective) and physical protection.

=== Thermal reactors ===
A [[Thermal-neutron reactor|thermal reactor]] is a [[nuclear reactor]] that uses slow or [[thermal neutrons]]. A [[neutron moderator]] is used to slow the [[neutron]]s emitted by fission to make them more likely to be captured by the fuel.

==== Very-high-temperature reactor (VHTR) ====
[[File:Very High Temperature Reactor.svg|right|thumb|Very-High-Temperature Reactor (VHTR)]]
{{Main article|Very high temperature reactor}}
{{see also|Fort St. Vrain Generating Station|High-temperature engineering test reactor|HTR-10}}
The '''very high temperature reactor''' concept uses a [[graphite]]-moderated core with a once-through [[uranium]] fuel cycle, using helium or molten salt as the [[Very high temperature reactor#Coolant|coolant]]. This reactor design envisions an outlet temperature of 1,000 °C. The reactor core can be either a prismatic-block or a [[pebble bed reactor]] design. The high temperatures enable applications such as process heat or [[hydrogen]] production via the thermochemical [[Sulfur-iodine cycle|iodine-sulfur]] process. It would also be [[Passive nuclear safety|passively safe]].

The planned construction of the first VHTR, the South African PBMR ([[pebble bed modular reactor]]), lost government funding in February, 2010.<ref>[http://www.powergenworldwide.com/index/display/articledisplay/6322207443/articles/power-engineering-international/volume-18/Issue_3/regulars/world-news/INTERNATIONAL.html South Africa to stop funding Pebble Bed nuclear reactor] {{webarchive|url=https://web.archive.org/web/20100909172743/http://www.powergenworldwide.com/index/display/articledisplay/6322207443/articles/power-engineering-international/volume-18/Issue_3/regulars/world-news/INTERNATIONAL.html |date=2010-09-09 }}</ref> A pronounced increase of costs and concerns about possible unexpected technical problems had discouraged potential investors and customers.

The [[Peoples Republic of China]] began construction of a 200-MW High Temperature Pebble bed reactor in 2012 as a successor to its [[HTR-10]].<ref>[http://www.nucnet.org/all-the-news/2013/01/07/china-begins-construction-of-first-generation-iv-htr-pm-unit Nucnet Report: 'China Begins Construction of First Generation IV HTR-PM Unit', 7 January 2013]</ref>

Also in 2012, as part of the [[Next Generation Nuclear Plant]] competition, [[Idaho National Laboratory]] approved a design similar to [[Areva]]'s prismatic block [http://us.areva.com/EN/home-3225/areva-inc-areva-htgr.html Antares reactor] as the chosen [[HTGR]] to be deployed as a prototype by 2021. It was in competition with [[General Atomics]]' [[Gas turbine modular helium reactor]] and [[Westinghouse Electric Company|Westinghouse]]'s [[Pebble Bed Modular Reactor]].<ref name="World nuclear news">{{cite web|url=http://www.world-nuclear-news.org/NN-Areva_modular_reactor_selected_for_NGNP_development-1502124.html|title=INL approves Antares design}}</ref>

[[X-energy]] was awarded a five-year $53M U.S. Department of Energy Advanced Reactor Concept Cooperative Agreement award to advance elements of their reactor development.<ref>[https://www.x-energy.com/doe-partnership]</ref>
The [[X-energy#Reactor Design|Xe-100]] is a pebble-bed modular reactor and will generate 200-MWt and approximately 76-MWe. The standard Xe-100 "four-pack" plant generates approximately 300-MWe and will fit on as few as 13 acres. All of the components for the Xe-100 will be road-transportable, and will be installed, rather than constructed, at the project site to streamline construction.<ref name="X-energy">{{cite web|url=https://www.x-energy.com/}}</ref>

==== Molten-salt reactor (MSR) ====
[[File:Molten Salt Reactor.svg|right|thumb|Molten Salt Reactor (MSR)]]
{{Main article|Molten salt reactor}}
{{see also|Liquid fluoride thorium reactor}}
A '''molten salt reactor'''<ref name="Roadmap"/> is a type of [[nuclear reactor]] where the primary [[coolant]], or even the fuel itself is a molten salt mixture. There have been many designs put forward for this type of reactor and a few prototypes built. The early concepts and many current ones rely on [[nuclear fuel]], perhaps [[uranium tetrafluoride]] (UF4) or [[thorium tetrafluoride]] (ThF4), dissolved in molten [[fluoride]] salt. The fluid would reach [[Nuclear reactor physics#Criticality|criticality]] by flowing into a core where [[graphite]] would serve as the [[neutron moderator|moderator]]. Many current concepts rely on fuel that is dispersed in a graphite matrix with the molten salt providing low pressure, high temperature cooling.

The Gen IV MSR is more accurately termed an [[epithermal neutron|epithermal reactor]] than a thermal reactor due to the average speed of the neutrons that would cause the fission events within its fuel being faster than [[thermal neutron]]s.<ref>{{cite web |url=https://inlportal.inl.gov/portal/server.pt?open=514&objID=1361&parentname=CommunityPage&parentid=10&mode=2&in_hi_userid=200&cached=true |title=Idaho National Laboratory detailing some current efforts at developing Gen. IV reactors}}</ref>

The principle of a MSR can be used for thermal, epithermal and fast reactors. Since 2005 the focus has moved towards a fast spectrum MSR (MSFR).<ref>H. Boussier, S. Delpech, V. Ghetta et Al. : The Molten Salt Reactor (MSR) in Generation IV: Overview and Perspectives, GIF SYMPOSIUM PROCEEDINGS/2012 ANNUAL REPORT, NEA No. 7141, pp95 [https://www.gen-4.org/gif/jcms/c_44720/annual-reports]
</ref>

While most MSR designs being pursued are largely derived from the 1960s [[Molten-Salt Reactor Experiment]](MSRE), variants of molten salt technology include the conceptual ''[[Dual fluid reactor]]'' which is being designed with lead as a cooling medium but molten salt fuel, commonly as the metal chloride e.g. [[Plutonium(III) chloride]], to aid in greater "nuclear waste" closed-fuel cycle capabilities.
Other notable approaches differing substantially from MSRE include the ''[[Stable Salt Reactor]]''(SSR) concept promoted by MOLTEX, which encases the molten salt in hundreds of the common solid [[fuel rod]]s that are already well established in the nuclear industry. This latter British design was found to be the most competitive for [[Small modular reactor]] development by a British-based consultancy firm ''Energy Process Development'' in 2015.<ref>[http://www.daretothink.org/europe-moltex-stable-salt-reactor/ Europe: Moltex’ Stable Salt Reactor]</ref><ref>[http://analysis.nuclearenergyinsider.com/moltex-energy-sees-uk-canada-smr-licensing-springboard-asia Moltex Energy sees UK, Canada SMR licensing as springboard to Asia Jun 28, 2016]</ref>

Another notable feature of the MSR is the possibility of a [[Thermal-neutron reactor|thermal spectrum]] nuclear [[Nuclear fuel cycle#Fuel cycles|waste-burner]]. Conventionally only fast spectrum reactors have been considered viable for [[Nuclear fuel cycle#Minor actinides recycling|utilization or reduction]] of the [[Spent nuclear fuel|spent nuclear stockpiles]]. The conceptual viability of a thermal waste-burner was first shown in a whitepaper by [[Seaborg Technologies]] spring 2015.<ref name="Seaborg Whitepaper 2015">{{cite web|url=https://seaborg.dk/s/Seaborg-whitepaper-2015.pdf|title=Thermal MSR waste burner benchmark}}</ref> Thermal waste-burning was achieved by replacing a fraction of the [[uranium]] in the spent nuclear fuel with [[thorium]]. The net production rate of [[transuranium element]] (e.g. [[plutonium]] and [[americium]]) is reduced below the consumption rate, thus reducing the magnitude of the [[Radioactive waste|nuclear storage problem]]. Without the [[nuclear proliferation]] concerns and other [[Fast-neutron reactor#Disadvantages|technical issues]] associated with a [[Fast-neutron reactor|fast reactor]].

==== Supercritical-water-cooled reactor (SCWR) ====
[[File:Supercritical-Water-Cooled Reactor.svg|right|thumb|Supercritical-Water-Cooled Reactor (SCWR)]]
{{Main article|Supercritical water reactor}}
The '''supercritical water reactor''' (SCWR)<ref name="Roadmap"/> is a [[reduced moderation water reactor]] concept that, due to the average speed of the neutrons that would cause the fission events within the fuel being faster than [[thermal neutron]]s, it is more accurately termed an [[epithermal neutron|epithermal reactor]] than a thermal reactor. It uses [[supercritical fluid|supercritical water]] as the working fluid. SCWRs are basically [[light water reactor]]s (LWR) operating at higher pressure and temperatures with a direct, once-through heat exchange cycle. As most commonly envisioned, it would operate on a direct cycle, much like a boiling water reactor ([[BWR]]), but since it uses supercritical water (not to be confused with [[Critical mass (nuclear)|critical mass]]) as the working fluid, it would have only one water phase present, which makes the supercritical heat exchange method more similar to a pressurized water reactor ([[Pressurized water reactor|PWR]]). It could operate at much higher temperatures than both current PWRs and BWRs.

Supercritical water-cooled reactors (SCWRs) are promising advanced nuclear systems because of their high [[thermal efficiency]] (i.e., about 45% vs. about 33% efficiency for current LWRs) and considerable plant simplification.

The main mission of the SCWR is generation of low-cost [[electricity]]. It is built upon two proven technologies, LWRs, which are the most commonly deployed power generating reactors in the world, and superheated [[fossil fuel]] fired [[boiler]]s, a large number of which are also in use around the world. The SCWR concept is being investigated by 32 organizations in 13 countries.{{citation needed|date=October 2012}}

Because SCWRs are water reactors they share the steam explosion and radioactive steam release hazards of BWRs and LWRs as well as the need for extremely expensive heavy duty pressure vessels, pipes, valves, and pumps. These shared problems are inherently more severe for SCWRs due to operation at higher temperatures.

A SCWR Design under development is the [[VVER]]-1700/393 (VVER-SCWR or VVER-SKD) — a Russian Supercritical-water-cooled reactor with double-inlet-core and a [[breeder reactor|breeding ratio]] of 0.95.<ref name="powertecrussia.com">{{cite web |url=http://www.powertecrussia.com/blog/tag/nuclear-power/ |title=Technology Developments & Plant Efficiency for the Russian Nuclear Power Generation Market Wednesday |date=March 24, 2010}}</ref>

=== Fast reactors ===
A [[Fast-neutron reactor|fast reactor]] directly uses the fast neutrons emitted by fission, without moderation. Unlike thermal neutron reactors, fast neutron reactors can be configured to "'''burn'''", or fission, all [[actinides]], and given enough time, therefore drastically reduce the actinides fraction in [[spent nuclear fuel]] produced by the present world fleet of thermal neutron [[light water reactor]]s, thus closing the [[nuclear fuel cycle]]. Alternatively, if configured differently, they can also [[breeder reactor|'''breed''']] more actinide fuel than they consume.

==== Gas-cooled fast reactor (GFR) ====
[[File:Gas-Cooled Fast Reactor Schemata.svg|right|thumb|Gas-Cooled Fast Reactor (GFR)]]
{{Main article|Gas-cooled fast reactor}}
The '''gas-cooled fast reactor''' (GFR)<ref name="Roadmap"/> system features a fast-neutron spectrum and closed fuel cycle for efficient conversion of [[Fertile material|fertile uranium]] and management of actinides. The reactor is [[helium]]-cooled and with an outlet temperature of 850 °C it is an evolution of the [[very-high-temperature reactor]] (VHTR) to a more sustainable fuel cycle. It will use a direct [[Brayton cycle]] [[Closed-cycle gas turbine|gas turbine]] for high thermal efficiency. Several fuel forms are being considered for their potential to operate at very high temperatures and to ensure an excellent retention of [[Nuclear fission|fission]] products: composite [[ceramic]] fuel, advanced fuel particles, or ceramic clad elements of actinide compounds. Core configurations are being considered based on pin- or plate-based fuel assemblies or prismatic blocks.

The European Sustainable Nuclear Industrial Initiative is funding three Generation IV reactor systems, one of which is a gas-cooled fast reactor, called ''Allegro'', 100 MW(t), which will be built in a central or eastern European country with construction expected to begin in 2018.<ref name="euronuclear.org">{{cite web|url=https://www.euronuclear.org/1-information/news/Gen-IV.htm |title=The European Sustainable Nuclear Industrial Initiative (ESNII) will support three Generation IV reactor systems: a sodium-cooled fast reactor, or SFR, called ''Astrid'' that is proposed by France; a gas-cooled fast reactor, GFR, called ''Allegro'' supported by central and eastern Europe; and a lead-cooled fast reactor, LFR, technology pilot called ''Myrrha'' that is proposed by Belgium. |deadurl=yes |archiveurl=https://web.archive.org/web/20131009042600/http://euronuclear.org/1-information/news/Gen-IV.htm |archivedate=2013-10-09 |df= }}</ref> The central European [[Visegrád Group]] are committed to pursuing the technology.<ref>{{cite web |url=http://www.alphagalileo.org/ViewItem.aspx?ItemId=133111&CultureCode=en |title=The V4G4 Centre of Excellence for performing joint research, development and innovation in the field of Generation-4 (G4) nuclear reactors have been established. 20 July 2013 National Center for Nuclear Research (NCBJ)}}</ref> In 2013 German, British, and French institutes finished a 3-year collaboration study on the follow on industrial scale design, known as ''GoFastR''.<ref>{{cite web|url=http://www.ist-world.org/ProjectDetails.aspx?ProjectId=5cb8f3f283574cc6b2bdbf72533172d8 |title=the European Gas cooled Fast Reactor. |deadurl=yes |archiveurl=https://web.archive.org/web/20131213091046/http://www.ist-world.org/ProjectDetails.aspx?ProjectId=5cb8f3f283574cc6b2bdbf72533172d8 |archivedate=2013-12-13 |df= }}</ref> They were funded by the EU's 7th FWP [[framework programme]], with the goal of making a sustainable VHTR.<ref>{{cite web |url=http://www.2020-horizon.com/GOFASTR-European-Gas-Cooled-Fast-Reactor%28GOFASTR%29-s312.html |title=The GOFASTR research program}}</ref>

==== Sodium-cooled fast reactor (SFR) ====
[[File:Sodium-Cooled Fast Reactor Schemata.svg|right|thumb|Pool design Sodium-Cooled Fast Reactor (SFR)]]
{{Main article|Sodium-cooled fast reactor}}
{{see also|Prototype Fast Breeder Reactor|Experimental Breeder Reactor II|S-PRISM|BN-800 reactor|Toshiba 4S|CFR-600}}

In India, the [[Fast Breeder Test Reactor]] reached criticality in October 1985. In September 2002, fuel burn-up in the FBTR for the first time reached the 100,000 megawatt-days per metric ton uranium (MWd/MTU) mark. This is considered an important milestone in breeder reactor technology. Using the experience gained from the operation of the FBTR, the [[Prototype Fast Breeder Reactor]], a 500 MWe Sodium cooled fast reactor is being built at a cost of INR 5,677 crores (~US$900 million) and is expected to be critical by June 2018. The PFBR will be followed by six more Commercial Fast Breeder Reactors (CFBRs) of 600 MWe each.

The SFR<ref name="Roadmap"/> is a project that builds on two closely related existing projects, the liquid metal [[Breeder reactor#Fast breeder reactor|fast breeder reactor]] and the [[integral fast reactor]].

The goals are to increase the efficiency of uranium usage by [[breeder reactor|breeding]] plutonium and eliminating the need for [[transuranic]] isotopes ever to leave the site. The reactor design uses an unmoderated core running on [[fast neutron]]s, designed to allow any transuranic isotope to be consumed (and in some cases used as fuel). In addition to the benefits of removing the long [[half-life]] transuranics from the waste cycle, the SFR fuel expands when the reactor overheats, and the chain reaction automatically slows down. In this manner, it is passively safe.<ref>{{cite web |url=http://www.ne.anl.gov/About/hn/logos-winter02-psr.shtml|title=Passively safe reactors rely on nature to keep them cool|author=David Baurac}}</ref>

The SFR reactor concept is cooled by liquid [[sodium]] and fueled by a metallic alloy of uranium and [[plutonium]] or [[spent nuclear fuel]], the "nuclear waste" of [[light water reactor]]s. The SFR fuel is contained in steel cladding with liquid sodium filling in the space between the clad elements which make up the fuel assembly. One of the design challenges of an SFR is the risks of handling sodium, which reacts explosively if it comes into contact with water. However, the use of liquid metal instead of water as coolant allows the system to work at atmospheric pressure, reducing the risk of leakage.

The European Sustainable Nuclear Industrial Initiative is funding three Generation IV reactor systems, one of which is a sodium-cooled fast reactor, called ''[[ASTRID (reactor)|ASTRID]]'', Advanced Sodium Technical Reactor for Industrial Demonstration, [[Areva]], [[Commissariat à l'énergie atomique et aux énergies alternatives|CEA]] and [[Électricité de France|EDF]] are leading the design with British collaboration.<ref>{{cite web |url=http://www.power-eng.com/articles/2010/11/areva--cea-secure.html |title=Areva, CEA secure EUR650m funding to develop ASTRID sodium-cooled Generation IV reactor 11/11/2010}}</ref><ref>{{cite web |url=http://www.powermag.com/uk-and-france-sign-landmark-civil-nuclear-cooperation-agreement/ |title=UK and France Sign Landmark Civil Nuclear Cooperation Agreement 02/22/2012 . POWERnews}}</ref> Astrid will be rated about 600 MWe and is proposed to be built in France, near to the [[Phénix]] reactor. A final decision in construction is to be made in 2019<ref name="euronuclear.org"/>

The [[China|PRC]]'s first commercial-scale, 800 MWe, fast neutron reactor, to be situated near [[Sanming]] in [[Fujian province]] will be a SFR. In 2009 an agreement was signed that would entail the Russian [[BN-800 reactor]] design to be sold to the PRC once it is completed, this would be the first time commercial-scale fast neutron reactors have ever been exported.<ref>{{cite web |url=http://www.world-nuclear-news.org/C-Joint_venture_launched_for_Chinese_fast_reactor-3004104.html |title=Joint venture launched for Chinese fast reactor}}</ref> The BN-800 reactor became operational in 2014.

The 400 MWe [[Fast Flux Test Facility]] operated successfully for ten years at the Hanford site in Washington State.

The 20 MWe [[EBR II]] operated successfully for over thirty years at the Idaho National Laboratory, until it was shut down in 1994.

GE Hitachi's [[PRISM (reactor)|PRISM]] reactor is an SFR with the primary purpose of reducing the half lives of the fissionable elements present in used nuclear fuel while generating electricity largely as a by-product.

==== Lead-cooled fast reactor (LFR) ====
[[File:Lead-Cooled Fast Reactor Schemata.svg|right|thumb|Lead-Cooled Fast Reactor (LFR)]]
{{Main article|Lead-cooled fast reactor}}
{{See also|MYRRHA}}
The '''lead-cooled fast reactor'''<ref name="Roadmap">{{cite journal|year=2002 |title=A Technology Roadmap for Generation IV Nuclear Energy Systems |last=US DOE Nuclear Energy Research Advisory Committee |volume=GIF-002-00 |url=http://nuclear.energy.gov/genIV/documents/gen_iv_roadmap.pdf |deadurl=yes |archiveurl=https://web.archive.org/web/20071129121214/http://nuclear.energy.gov/genIV/documents/gen_iv_roadmap.pdf |archivedate=2007-11-29 |df= }}</ref> features a fast-neutron-spectrum [[lead]] or [[lead]]/[[bismuth]] [[eutectic]] ([[Lead-bismuth eutectic|LBE]]) liquid-metal-cooled reactor with a closed [[Nuclear fuel cycle|fuel cycle]]. Options include a range of plant ratings, including a "battery" of 50 to 150 MW of electricity that features a very long refueling interval, a modular system rated at 300 to 400 MW, and a large monolithic plant option at 1,200 MW (The term ''battery'' refers to the long-life, factory-fabricated core, not to any provision for electrochemical energy conversion). The fuel is metal or nitride-based containing [[Fertile material|fertile uranium]] and [[transuranic]]s. The LFR is cooled by natural [[convection]] with a reactor outlet coolant temperature of 550 °C, possibly ranging up to 800 °C with advanced materials. The higher temperature enables the production of [[Thermochemical cycle|hydrogen by thermochemical processes]].

The European Sustainable Nuclear Industrial Initiative is funding three Generation IV reactor systems, one of which is a lead-cooled fast reactor that is also an [[Subcritical reactor|accelerator-driven sub-critical]] reactor, called ''[[MYRRHA]]'', 100 MW(t), which will be built in [[Belgium]] with construction expected to begin after 2014 and the industrial scale version, known as ''Alfred'', slated to be constructed sometime after 2017. A reduced-power model of Myrrha called ''Guinevere'' was started up at [[Mol, Belgium|Mol]] in March 2009.<ref name="euronuclear.org"/> In 2012 the research team reported that Guinevere was operational.<ref>{{cite news|last1=Hellemans|first1=Alexander|title=Reactor-Accelerator Hybrid Achieves Successful Test Run|url=http://news.sciencemag.org/physics/2012/01/reactor-accelerator-hybrid-achieves-successful-test-run|accessdate=29 December 2014|work=Science Insider|date=12 January 2012}}</ref>

Two other lead-cooled fast reactors under development are the SVBR-100, a modular 100 MWe lead-bismuth cooled fast neutron reactor concept designed by OKB [[Gidropress]] in Russia and the [[BREST (Reactor)|BREST-OD-300]] (Lead-cooled fast reactor) 300 MWe, to be developed after the SVBR-100, and built over 2016-20, it will dispense with the [[Uranium-238|fertile blanket]] around the core and will supersede the sodium cooled [[BN-600 reactor]] design, to purportedly give enhanced proliferation resistance.<ref name="powertecrussia.com"/>

== Advantages and disadvantages ==
Relative to current nuclear power plant technology, the claimed benefits for 4th generation reactors include:
* Nuclear waste that remains radioactive for a few centuries instead of millennia<ref>{{cite web |title=Strategies to Address Global Warming |url=http://www.columbia.edu/~jeh1/mailings/2009/20090713_Strategies.pdf}}</ref>
* 100–300 times more energy yield from the same amount of nuclear fuel<ref>{{cite web |title=4th Generation Nuclear Power |url=http://www.ossfoundation.us/projects/energy/nuclear}}</ref>
* Broader range of fuels, and even unencapsulated raw fuels (non-pebble [[Molten Salt Reactor|MSR]], [[Liquid fluoride thorium reactor|LFTR]]).
* In some reactors, the ability to consume existing nuclear waste in the production of electricity, that is, a Closed [[nuclear fuel cycle]]. This strengthens the argument to deem [[nuclear power as renewable energy]].
* Improved operating safety features, such as (depending on design) avoidance of pressurized operation, automatic passive (unpowered, uncommanded) reactor shutdown, avoidance of water cooling and the associated risks of loss of water (leaks or boiling) and hydrogen generation/explosion and contamination of coolant water.

Nuclear reactors do not emit CO2 during operation, although like all [[low carbon power]] sources, the mining and construction phase can result in CO2 emissions, if energy sources which are not carbon neutral (such as fossil fuels), or CO2 emitting cements are used during the construction process.
A 2012 [[Yale University]] review published in the Journal of Industrial Ecology analyzing {{CO2}} [[life cycle assessment]] (LCA) emissions from [[nuclear power]] determined that:<ref name="Warner + Heath, JoIE">Warner, Ethan S.; Heath, Garvin A. [http://onlinelibrary.wiley.com/doi/10.1111/j.1530-9290.2012.00472.x/full Life Cycle Greenhouse Gas Emissions of Nuclear Electricity Generation: Systematic Review and Harmonization], ''Journal of Industrial Ecology'', [[Yale University]], published online April 17, 2012, {{doi|10.1111/j.1530-9290.2012.00472.x}}</ref>
{{Quote|The collective LCA literature indicates that life cycle [[Greenhouse gas|GHG]] [greenhouse gas] emissions from nuclear power are only a fraction of traditional fossil sources and comparable to renewable technologies.}}
Although the paper primarily dealt with data from [[Generation II reactor]]s, and did not analyze the {{CO2}} emissions by 2050 of the presently under construction [[Generation III reactor]]s, it did summarize the Life Cycle Assessment findings of in development reactor technologies.{{Quote|FBRs ['[[Fast Breeder Reactor]]s'] have been evaluated in the LCA literature. The limited literature that evaluates this potential future technology reports [[median]] life cycle GHG emissions... similar to or lower than LWRs [Gen II [[light water reactor]]s] and purports to consume little or no [[uranium market|uranium ore]].}}

A specific risk of the sodium-cooled fast reactor is related to using metallic sodium as a coolant. In case of a breach, sodium explosively reacts with water. Fixing breaches may also prove dangerous, as the cheapest noble gas [[argon]] is also used to prevent sodium oxidation. Argon, like helium, can displace oxygen in the air and can pose [[hypoxia (environmental)|hypoxia]] concerns, so workers may be exposed to this additional risk. This is a pertinent problem as demonstrated by the events at the [[LMFBR|loop type]] [[Monju Nuclear Power Plant|Prototype Fast Breeder Reactor Monju]] at Tsuruga, Japan.<ref>{{cite news |title=Japan Strains to Fix a Reactor Damaged Before Quake |url=https://www.nytimes.com/2011/06/18/world/asia/18japan.html | work=The New York Times | first=Hiroko |last=Tabuchi |date=17 June 2011}}</ref>
Using lead or molten salts mitigates this problem by making the coolant less reactive and allowing a high freezing temperature and low pressure in case of a leak. Disadvantages of lead compared to sodium are much higher viscosity, much higher density, lower heat capacity, and more radioactive neutron activation products.

In many cases, there is already a large amount of experience built up with numerous proof of concept Gen IV designs. For example, the reactors at [[Fort St. Vrain Generating Station]] and [[HTR-10]] are similar to the proposed Gen IV [[VHTR]] designs, and the [[LMFBR|pool type]] [[EBR-II]], [[Phénix]] and [[BN-600]] reactor are similar to the proposed pool type Gen IV Sodium Cooled Fast reactors being designed.

== Table of designs ==

{| class=wikitable
|+ Summary of designs for generation IV reactors<ref>https://www.gen-4.org/gif/upload/docs/application/pdf/2013-09/gif_rd_outlook_for_generation_iv_nuclear_energy_systems.pdf</ref>
|-
! System
! Neutron Spectrum
! Coolant
! Temperature (°C)
! Fuel Cycle
! Size (MW)
!Example developers
|-
| [[Very-high-temperature reactor|VHTR]]
| Thermal
| Helium
| 900–1000
| Open
| 250–300
|[[Japan Atomic Energy Agency|JAEA]] ([[High-temperature engineering test reactor|HTTR]]), [[Tsinghua University]] ([[HTR-10]]), [[X-energy]]<ref name="energy.gov">{{cite web|title=Energy Department Announces New Investments in Advanced Nuclear Power Reactors...|url=https://www.energy.gov/articles/energy-department-announces-new-investments-advanced-nuclear-power-reactors-help-meet|website=[[United States Department of Energy|US Department of Energy]]|accessdate=16 January 2016}}</ref>
|-
| [[Sodium-cooled fast reactor|SFR]]
| Fast
| Sodium
| 550
| Closed
| 30–150, 300–1500, 1000–2000
|[[TerraPower]] ([[Traveling wave reactor|TWR]]), [[Toshiba]] ([[Toshiba 4S|4S]]), [[GE Hitachi Nuclear Energy]] ([[PRISM (reactor)|PRISM]])
|-
| [[Supercritical water reactor|SCWR]]
| Thermal or fast
| Water
| 510–625
| Open or closed
| 300–700, 1000–1500
|
|-
| [[Gas-cooled fast reactor|GFR]]
| Fast
| Helium
| 850
| Closed
| 1200
|[[Energy Multiplier Module]]
|-
| [[Lead-cooled fast reactor|LFR]]
| Fast
| Lead
| 480–800
| Closed
| 20–180, 300–1200, 600–1000
|
|-
| [[Molten salt reactor|MSR]]
| Fast or thermal
| Fluoride or chloride salts
| 700–800
| Closed
| 250, 1000
|[[Seaborg Technologies]], [[TerraPower]], [[Stable Salt Reactor|Moltex Energy]], [[Flibe Energy]] ([[Liquid fluoride thorium reactor|LFTR]]), [[Transatomic Power]], Thorium Tech Solution ([[Fuji Molten Salt Reactor|FUJI MSR]]), Terrestrial Energy ([[IMSR]]), [[Southern Company Services|Southern Company]]<ref name="energy.gov"/>, [[Elysium Industries]]<ref>http://www.elysiumindustries.com/</ref>
|-
| [[Dual fluid reactor|DFR]]
| Fast
| Lead
| 1000
| Closed
| 500–1500
| Institute for Solid-State Nuclear Physics<ref name=ifk>{{cite web |url=https://festkoerper-kernphysik.de/dfr.pdf |title=Dual Fluid Reactor - IFK |date=2013-06-16 |website=festkoerper-kernphysik.de |publisher= Institut für Festkörper-Kernphysik |format=PDF |location=Berlin, Germany |access-date=2017-08-28}}</ref>, [[Aristos Power]] <ref name=HSR>{{|url=http://aristospower.tk |title=Hard Spectrum Reactor - HSR</ref>
|}

== See also ==
{{portal|Energy|Nuclear technology}}
{{colbegin}}
* [[Nuclear reactor]]
* [[Nuclear material]]
* [[Nuclear physics]]
* [[List of reactor types#Reactor types|List of reactor types]]
* [[Generation II reactor]]
* [[Generation III reactor]]
* [[Integral Fast Reactor]]
* [[Liquid fluoride thorium reactor]]
* [[Breeder reactor]]
* [[Small modular reactor]]
{{colend}}

==References==
{{Reflist|30em}}

== External links ==
* [https://inlportal.inl.gov/portal/server.pt?open=514&objID=1361&parentname=CommunityPage&parentid=10&mode=2&in_hi_userid=200&cached=true Article from Idaho National Laboratory detailing some current efforts at developing Gen. IV reactors.]
* [http://www.gen-4.org/ Generation IV International Forum (GIF)]
* [https://web.archive.org/web/20070205115654/http://nuclear.energy.gov/genIV/neGenIV1.html U.S. Department of Energy Office of Nuclear Energy, Science and Technology]
* [https://web.archive.org/web/20060512033030/http://www.engr.utk.edu/nuclear/colloquia/slides/Gen%20IV%20U-Tenn%20Presentation.pdf Gen IV presentation]
* [http://www.ecology.at/ecology/files/pr577_1.pdf Science or Fiction - Is there a Future for Nuclear?] (Nov. 2007) - A publication from the Austrian [[Ecology Institute (Austria)|Ecology Institute]] about 'Generation IV' and Fusion reactors.
* {{cite web |url=http://memagazine.asme.org/Articles/2011/December/Nuclear_Power_After_Fukushima.cfm |title=Nuclear Power After Fukushima |author=Gail H. Marcus |date=December 2011 |work=Mechanical Engineering (the magazine of [[ASME]]) |accessdate=23 January 2012}} "In the wake of a severe plant accident, advanced reactor designs are getting renewed attention."
* [http://www.itheo.org/ International Thorium Energy Organisation - www.IThEO.org]
* [http://www.ithec.org/ International Thorium Energy Committee - iThEC]

{{Nuclear fission reactors}}

[[Category:Nuclear power reactor types]]
[[Category:Idaho National Laboratory]]

Benutzer:Snackroeg/Kernreaktoren der Generation 5

2018-02-25T06:22:39Z

Boundarylayer:

{{update|date=October 2017}}
[[File:GenIVRoadmap-en.svg|thumb|480px|Nuclear Energy Systems Deployable no later than 2030 and offering significant advances in sustainability, safety and reliability, and economics]]

'''Generation IV reactors''' ('''Gen IV''') are a set of [[nuclear reactor]] designs currently being researched for commercial applications by the Generation IV International Forum, with [[Technology readiness level]]s varying between the level requiring a demonstration, to economical competitive implementation.<ref>{{Cite journal|last=Locatelli|first=Giorgio|last2=Mancini|first2=Mauro|last3=Todeschini|first3=Nicola|date=2013-10-01|title=Generation IV nuclear reactors: Current status and future prospects|url=http://www.sciencedirect.com/science/article/pii/S0301421513006083|journal=Energy Policy|volume=61|pages=1503–1520|doi=10.1016/j.enpol.2013.06.101}}</ref> They are motivated by a variety of goals including improved safety, sustainability, efficiency, and cost.

The most developed Gen IV reactor design, the [[sodium fast reactor]], has received the greatest share of funding over the years, with the principle Gen IV aspect of the design, relating in largest part to the development of a sustainable [[nuclear fuel cycle|closed fuel cycle]] for the reactor. Amongst nuclear engineers the [[molten-salt reactor]], the least developed and funded technology, is considered as potentially having the greatest [[inherent safety]] of the six models.<ref>[https://www.scientificamerican.com/article/can-sodium-save-nuclear-power/ Can Sodium Save Nuclear Power? Scientific American]</ref><ref>{{cite journal |last1=Moir |first1=Ralph |last2=Teller |first2=Edward |year=2005 |title=Thorium-Fueled Underground Power Plant Based on Molten Salt Technology |journal=Nuclear Technology |volume=151 |issue=3 |pages=334–340 |publisher=[[American Nuclear Society]] |url=http://www.new.ans.org/pubs/journals/nt/a_3655 |accessdate=March 22, 2012 }}</ref> The [[hydrogen economy]], the use of hydrogen to produce [[Carbon-neutral fuel]]s, is deemed as strengthening the economic case for the two most efficient models, the two [[Very-high-temperature reactor|high temperature reactor]]s designs.<ref>[https://www.sciencedirect.com/science/article/pii/S0301421513006083 Generation IV nuclear reactors: Current status and future prospects doi.org/10.1016/j.enpol.2013.06.101]</ref>

The majority of the 6 designs are generally not expected to be available for commercial construction until 2020–30.<ref name="Generation IV">[http://www.world-nuclear.org/info/Nuclear-Fuel-Cycle/Power-Reactors/Generation-IV-Nuclear-Reactors/]</ref> Presently the majority of reactors in operation around the world are considered [[Generation II reactor|second generation reactor]] systems, as the vast majority of the [[Nuclear reactor#Classification by generation|first generation]] systems were retired some time ago, and there are only a dozen or so [[Generation III reactor]]s in operation as of 2014.
[[Nuclear reactor#Generation V+ reactors|Generation V reactors]] refer to reactors that are purely theoretical and are therefore not yet considered feasible in the short term, resulting in limited [[R&D]] funding.

== History ==
The Generation IV International Forum (GIF) is "a co-operative international endeavour which was set up to carry out the research and development needed to establish the feasibility and performance capabilities of the next generation nuclear energy systems."<ref>{{Cite web|url=https://www.gen-4.org/gif/jcms/c_9260/public|title=GIF Portal - Home - Public|website=www.gen-4.org|access-date=2016-07-25}}</ref> It was founded in 2001. Currently active members of the Generation IV International Forum (GIF) include: [[Australia]], [[Canada]], [[China]], the [[European Atomic Energy Community]] (Euratom), [[France]], [[Japan]], [[Russia]], [[South Africa]], [[South Korea]], [[Switzerland]], and the [[United States]]. The non-active members are [[Argentina]], [[Brazil]], and the [[United Kingdom]].<ref name="gen-4">{{cite web|url=https://www.gen-4.org/gif/jcms/c_9492/members|title=GIF Membership|website=gen-4.org|accessdate=28 October 2014}}</ref> Switzerland joined in 2002, Euratom in 2003, and China and Russia in 2006. The remaining countries (excluding Australia) were founding members.<ref name="gen-4" />

The 36th GIF meeting in [[Brussels]] was held in November 2013.<ref>{{cite web|url=https://www.energy.gov/ne/articles/generation-iv-international-forum-updates-technology-roadmap-and-builds-future|title=generation IV international forum updates technology roadmap and builds future. DOE}}</ref><ref>{{cite web|url=http://events.r20.constantcontact.com/register/event?llr=mscrkjkab&oeidk=a07e7melf609716b2c6 |title=The Generation IV international forum holds their 36th meeting on Monday 18th Nov 2013 in Brussels. }}{{dead link|date=January 2017 |bot=InternetArchiveBot |fix-attempted=yes }}</ref> The ''Technology Roadmap Update for Generation IV Nuclear Energy Systems'' was published in January 2014 which details R&D objectives for the next decade.<ref>[https://web.archive.org/web/20140625102915/https://www.gen-4.org/gif/upload/docs/application/pdf/2014-03/gif-tru2014.pdf Technology Roadmap Update for Generation IV Nuclear Energy Systems]</ref> A breakdown of the reactor designs being researched by each forum member has been made available.<ref>[https://web.archive.org/web/20140708023538/https://www.gen-4.org/gif/upload/docs/application/pdf/2014-03/gif_overview_presentation_v9_final3_web.pdf Generation IV International Forum, overview, John E. Kelly, page 15]</ref>

[[Nuclear power in Australia|Australia]] joined the forum in 2016.<ref>https://archive.is/20160907131656/https://www.gen-4.org/gif/jcms/c_71564/australia-joins-the-generation-iv-international-forum</ref>

In January 2018, it was reported that "the first installation of the pressure vessel cover of the world's first Gen IV reactor" had been completed on the [[HTR-PM]].<ref>http://www.world-nuclear-news.org/NN-First-HTR-PM-vessel-head-in-place-0401185.html</ref>

== Reactor types ==
Many reactor types were considered initially; however, the list was downsized to focus on the most promising technologies and those that could most likely meet the goals of the Gen IV initiative.<ref name="Generation IV"/> Three systems are nominally [[thermal reactor]]s and four are [[fast reactor]]s. The Very High Temperature Reactor (VHTR) is also being researched for potentially providing high quality process heat for [[thermochemical cycle|hydrogen production]]. The fast reactors offer the possibility of burning [[actinides]] to further reduce waste and of being able to "[[breeder reactor|breed more fuel]]" than they consume. These systems offer significant advances in sustainability, safety and reliability, economics, proliferation resistance (depending on perspective) and physical protection.

=== Thermal reactors ===
A [[Thermal-neutron reactor|thermal reactor]] is a [[nuclear reactor]] that uses slow or [[thermal neutrons]]. A [[neutron moderator]] is used to slow the [[neutron]]s emitted by fission to make them more likely to be captured by the fuel.

==== Very-high-temperature reactor (VHTR) ====
[[File:Very High Temperature Reactor.svg|right|thumb|Very-High-Temperature Reactor (VHTR)]]
{{Main article|Very high temperature reactor}}
{{see also|Fort St. Vrain Generating Station|High-temperature engineering test reactor|HTR-10}}
The '''very high temperature reactor''' concept uses a [[graphite]]-moderated core with a once-through [[uranium]] fuel cycle, using helium or molten salt as the [[Very high temperature reactor#Coolant|coolant]]. This reactor design envisions an outlet temperature of 1,000 °C. The reactor core can be either a prismatic-block or a [[pebble bed reactor]] design. The high temperatures enable applications such as process heat or [[hydrogen]] production via the thermochemical [[Sulfur-iodine cycle|iodine-sulfur]] process. It would also be [[Passive nuclear safety|passively safe]].

The planned construction of the first VHTR, the South African PBMR ([[pebble bed modular reactor]]), lost government funding in February, 2010.<ref>[http://www.powergenworldwide.com/index/display/articledisplay/6322207443/articles/power-engineering-international/volume-18/Issue_3/regulars/world-news/INTERNATIONAL.html South Africa to stop funding Pebble Bed nuclear reactor] {{webarchive|url=https://web.archive.org/web/20100909172743/http://www.powergenworldwide.com/index/display/articledisplay/6322207443/articles/power-engineering-international/volume-18/Issue_3/regulars/world-news/INTERNATIONAL.html |date=2010-09-09 }}</ref> A pronounced increase of costs and concerns about possible unexpected technical problems had discouraged potential investors and customers.

The [[Peoples Republic of China]] began construction of a 200-MW High Temperature Pebble bed reactor in 2012 as a successor to its [[HTR-10]].<ref>[http://www.nucnet.org/all-the-news/2013/01/07/china-begins-construction-of-first-generation-iv-htr-pm-unit Nucnet Report: 'China Begins Construction of First Generation IV HTR-PM Unit', 7 January 2013]</ref>

Also in 2012, as part of the [[Next Generation Nuclear Plant]] competition, [[Idaho National Laboratory]] approved a design similar to [[Areva]]'s prismatic block [http://us.areva.com/EN/home-3225/areva-inc-areva-htgr.html Antares reactor] as the chosen [[HTGR]] to be deployed as a prototype by 2021. It was in competition with [[General Atomics]]' [[Gas turbine modular helium reactor]] and [[Westinghouse Electric Company|Westinghouse]]'s [[Pebble Bed Modular Reactor]].<ref name="World nuclear news">{{cite web|url=http://www.world-nuclear-news.org/NN-Areva_modular_reactor_selected_for_NGNP_development-1502124.html|title=INL approves Antares design}}</ref>

[[X-energy]] was awarded a five-year $53M U.S. Department of Energy Advanced Reactor Concept Cooperative Agreement award to advance elements of their reactor development.<ref>[https://www.x-energy.com/doe-partnership]</ref>
The [[X-energy#Reactor Design|Xe-100]] is a pebble-bed modular reactor and will generate 200-MWt and approximately 76-MWe. The standard Xe-100 "four-pack" plant generates approximately 300-MWe and will fit on as few as 13 acres. All of the components for the Xe-100 will be road-transportable, and will be installed, rather than constructed, at the project site to streamline construction.<ref name="X-energy">{{cite web|url=https://www.x-energy.com/}}</ref>

==== Molten-salt reactor (MSR) ====
[[File:Molten Salt Reactor.svg|right|thumb|Molten Salt Reactor (MSR)]]
{{Main article|Molten salt reactor}}
{{see also|Liquid fluoride thorium reactor}}
A '''molten salt reactor'''<ref name="Roadmap"/> is a type of [[nuclear reactor]] where the primary [[coolant]], or even the fuel itself is a molten salt mixture. There have been many designs put forward for this type of reactor and a few prototypes built. The early concepts and many current ones rely on [[nuclear fuel]], perhaps [[uranium tetrafluoride]] (UF4) or [[thorium tetrafluoride]] (ThF4), dissolved in molten [[fluoride]] salt. The fluid would reach [[Nuclear reactor physics#Criticality|criticality]] by flowing into a core where [[graphite]] would serve as the [[neutron moderator|moderator]]. Many current concepts rely on fuel that is dispersed in a graphite matrix with the molten salt providing low pressure, high temperature cooling.

The Gen IV MSR is more accurately termed an [[epithermal neutron|epithermal reactor]] than a thermal reactor due to the average speed of the neutrons that would cause the fission events within its fuel being faster than [[thermal neutron]]s.<ref>{{cite web |url=https://inlportal.inl.gov/portal/server.pt?open=514&objID=1361&parentname=CommunityPage&parentid=10&mode=2&in_hi_userid=200&cached=true |title=Idaho National Laboratory detailing some current efforts at developing Gen. IV reactors}}</ref>

The principle of a MSR can be used for thermal, epithermal and fast reactors. Since 2005 the focus has moved towards a fast spectrum MSR (MSFR).<ref>H. Boussier, S. Delpech, V. Ghetta et Al. : The Molten Salt Reactor (MSR) in Generation IV: Overview and Perspectives, GIF SYMPOSIUM PROCEEDINGS/2012 ANNUAL REPORT, NEA No. 7141, pp95 [https://www.gen-4.org/gif/jcms/c_44720/annual-reports]
</ref>

While most MSR designs being pursued are largely derived from the 1960s [[Molten-Salt Reactor Experiment]](MSRE), variants of molten salt technology include the conceptual ''[[Dual fluid reactor]]'' which is being designed with lead as a cooling medium but molten salt fuel, commonly as the metal chloride e.g. [[Plutonium(III) chloride]], to aid in greater "nuclear waste" closed-fuel cycle capabilities.
Other notable approaches differing substantially from MSRE include the ''[[Stable Salt Reactor]]''(SSR) concept promoted by MOLTEX, which encases the molten salt in hundreds of the common solid [[fuel rod]]s that are already well established in the nuclear industry. This latter British design was found to be the most competitive for [[Small modular reactor]] development by a British-based consultancy firm ''Energy Process Development'' in 2015.<ref>[http://www.daretothink.org/europe-moltex-stable-salt-reactor/ Europe: Moltex’ Stable Salt Reactor]</ref><ref>[http://analysis.nuclearenergyinsider.com/moltex-energy-sees-uk-canada-smr-licensing-springboard-asia Moltex Energy sees UK, Canada SMR licensing as springboard to Asia Jun 28, 2016]</ref>

Another notable feature of the MSR is the possibility of a [[Thermal-neutron reactor|thermal spectrum]] nuclear [[Nuclear fuel cycle#Fuel cycles|waste-burner]]. Conventionally only fast spectrum reactors have been considered viable for [[Nuclear fuel cycle#Minor actinides recycling|utilization or reduction]] of the [[Spent nuclear fuel|spent nuclear stockpiles]]. The conceptual viability of a thermal waste-burner was first shown in a whitepaper by [[Seaborg Technologies]] spring 2015.<ref name="Seaborg Whitepaper 2015">{{cite web|url=https://seaborg.dk/s/Seaborg-whitepaper-2015.pdf|title=Thermal MSR waste burner benchmark}}</ref> Thermal waste-burning was achieved by replacing a fraction of the [[uranium]] in the spent nuclear fuel with [[thorium]]. The net production rate of [[transuranium element]] (e.g. [[plutonium]] and [[americium]]) is reduced below the consumption rate, thus reducing the magnitude of the [[Radioactive waste|nuclear storage problem]]. Without the [[nuclear proliferation]] concerns and other [[Fast-neutron reactor#Disadvantages|technical issues]] associated with a [[Fast-neutron reactor|fast reactor]].

==== Supercritical-water-cooled reactor (SCWR) ====
[[File:Supercritical-Water-Cooled Reactor.svg|right|thumb|Supercritical-Water-Cooled Reactor (SCWR)]]
{{Main article|Supercritical water reactor}}
The '''supercritical water reactor''' (SCWR)<ref name="Roadmap"/> is a [[reduced moderation water reactor]] concept that, due to the average speed of the neutrons that would cause the fission events within the fuel being faster than [[thermal neutron]]s, it is more accurately termed an [[epithermal neutron|epithermal reactor]] than a thermal reactor. It uses [[supercritical fluid|supercritical water]] as the working fluid. SCWRs are basically [[light water reactor]]s (LWR) operating at higher pressure and temperatures with a direct, once-through heat exchange cycle. As most commonly envisioned, it would operate on a direct cycle, much like a boiling water reactor ([[BWR]]), but since it uses supercritical water (not to be confused with [[Critical mass (nuclear)|critical mass]]) as the working fluid, it would have only one water phase present, which makes the supercritical heat exchange method more similar to a pressurized water reactor ([[Pressurized water reactor|PWR]]). It could operate at much higher temperatures than both current PWRs and BWRs.

Supercritical water-cooled reactors (SCWRs) are promising advanced nuclear systems because of their high [[thermal efficiency]] (i.e., about 45% vs. about 33% efficiency for current LWRs) and considerable plant simplification.

The main mission of the SCWR is generation of low-cost [[electricity]]. It is built upon two proven technologies, LWRs, which are the most commonly deployed power generating reactors in the world, and superheated [[fossil fuel]] fired [[boiler]]s, a large number of which are also in use around the world. The SCWR concept is being investigated by 32 organizations in 13 countries.{{citation needed|date=October 2012}}

Because SCWRs are water reactors they share the steam explosion and radioactive steam release hazards of BWRs and LWRs as well as the need for extremely expensive heavy duty pressure vessels, pipes, valves, and pumps. These shared problems are inherently more severe for SCWRs due to operation at higher temperatures.

A SCWR Design under development is the [[VVER]]-1700/393 (VVER-SCWR or VVER-SKD) — a Russian Supercritical-water-cooled reactor with double-inlet-core and a [[breeder reactor|breeding ratio]] of 0.95.<ref name="powertecrussia.com">{{cite web |url=http://www.powertecrussia.com/blog/tag/nuclear-power/ |title=Technology Developments & Plant Efficiency for the Russian Nuclear Power Generation Market Wednesday |date=March 24, 2010}}</ref>

=== Fast reactors ===
A [[Fast-neutron reactor|fast reactor]] directly uses the fast neutrons emitted by fission, without moderation. Unlike thermal neutron reactors, fast neutron reactors can be configured to "'''burn'''", or fission, all [[actinides]], and given enough time, therefore drastically reduce the actinides fraction in [[spent nuclear fuel]] produced by the present world fleet of thermal neutron [[light water reactor]]s, thus closing the [[nuclear fuel cycle]]. Alternatively, if configured differently, they can also [[breeder reactor|'''breed''']] more actinide fuel than they consume.

==== Gas-cooled fast reactor (GFR) ====
[[File:Gas-Cooled Fast Reactor Schemata.svg|right|thumb|Gas-Cooled Fast Reactor (GFR)]]
{{Main article|Gas-cooled fast reactor}}
The '''gas-cooled fast reactor''' (GFR)<ref name="Roadmap"/> system features a fast-neutron spectrum and closed fuel cycle for efficient conversion of [[Fertile material|fertile uranium]] and management of actinides. The reactor is [[helium]]-cooled and with an outlet temperature of 850 °C it is an evolution of the [[very-high-temperature reactor]] (VHTR) to a more sustainable fuel cycle. It will use a direct [[Brayton cycle]] [[Closed-cycle gas turbine|gas turbine]] for high thermal efficiency. Several fuel forms are being considered for their potential to operate at very high temperatures and to ensure an excellent retention of [[Nuclear fission|fission]] products: composite [[ceramic]] fuel, advanced fuel particles, or ceramic clad elements of actinide compounds. Core configurations are being considered based on pin- or plate-based fuel assemblies or prismatic blocks.

The European Sustainable Nuclear Industrial Initiative is funding three Generation IV reactor systems, one of which is a gas-cooled fast reactor, called ''Allegro'', 100 MW(t), which will be built in a central or eastern European country with construction expected to begin in 2018.<ref name="euronuclear.org">{{cite web|url=https://www.euronuclear.org/1-information/news/Gen-IV.htm |title=The European Sustainable Nuclear Industrial Initiative (ESNII) will support three Generation IV reactor systems: a sodium-cooled fast reactor, or SFR, called ''Astrid'' that is proposed by France; a gas-cooled fast reactor, GFR, called ''Allegro'' supported by central and eastern Europe; and a lead-cooled fast reactor, LFR, technology pilot called ''Myrrha'' that is proposed by Belgium. |deadurl=yes |archiveurl=https://web.archive.org/web/20131009042600/http://euronuclear.org/1-information/news/Gen-IV.htm |archivedate=2013-10-09 |df= }}</ref> The central European [[Visegrád Group]] are committed to pursuing the technology.<ref>{{cite web |url=http://www.alphagalileo.org/ViewItem.aspx?ItemId=133111&CultureCode=en |title=The V4G4 Centre of Excellence for performing joint research, development and innovation in the field of Generation-4 (G4) nuclear reactors have been established. 20 July 2013 National Center for Nuclear Research (NCBJ)}}</ref> In 2013 German, British, and French institutes finished a 3-year collaboration study on the follow on industrial scale design, known as ''GoFastR''.<ref>{{cite web|url=http://www.ist-world.org/ProjectDetails.aspx?ProjectId=5cb8f3f283574cc6b2bdbf72533172d8 |title=the European Gas cooled Fast Reactor. |deadurl=yes |archiveurl=https://web.archive.org/web/20131213091046/http://www.ist-world.org/ProjectDetails.aspx?ProjectId=5cb8f3f283574cc6b2bdbf72533172d8 |archivedate=2013-12-13 |df= }}</ref> They were funded by the EU's 7th FWP [[framework programme]], with the goal of making a sustainable VHTR.<ref>{{cite web |url=http://www.2020-horizon.com/GOFASTR-European-Gas-Cooled-Fast-Reactor%28GOFASTR%29-s312.html |title=The GOFASTR research program}}</ref>

==== Sodium-cooled fast reactor (SFR) ====
[[File:Sodium-Cooled Fast Reactor Schemata.svg|right|thumb|Pool design Sodium-Cooled Fast Reactor (SFR)]]
{{Main article|Sodium-cooled fast reactor}}
{{see also|Prototype Fast Breeder Reactor|Experimental Breeder Reactor II|S-PRISM|BN-800 reactor|Toshiba 4S|CFR-600}}

In India, the [[Fast Breeder Test Reactor]] reached criticality in October 1985. In September 2002, fuel burn-up in the FBTR for the first time reached the 100,000 megawatt-days per metric ton uranium (MWd/MTU) mark. This is considered an important milestone in breeder reactor technology. Using the experience gained from the operation of the FBTR, the [[Prototype Fast Breeder Reactor]], a 500 MWe Sodium cooled fast reactor is being built at a cost of INR 5,677 crores (~US$900 million) and is expected to be critical by June 2018. The PFBR will be followed by six more Commercial Fast Breeder Reactors (CFBRs) of 600 MWe each.

The SFR<ref name="Roadmap"/> is a project that builds on two closely related existing projects, the liquid metal [[Breeder reactor#Fast breeder reactor|fast breeder reactor]] and the [[integral fast reactor]].

The goals are to increase the efficiency of uranium usage by [[breeder reactor|breeding]] plutonium and eliminating the need for [[transuranic]] isotopes ever to leave the site. The reactor design uses an unmoderated core running on [[fast neutron]]s, designed to allow any transuranic isotope to be consumed (and in some cases used as fuel). In addition to the benefits of removing the long [[half-life]] transuranics from the waste cycle, the SFR fuel expands when the reactor overheats, and the chain reaction automatically slows down. In this manner, it is passively safe.<ref>{{cite web |url=http://www.ne.anl.gov/About/hn/logos-winter02-psr.shtml|title=Passively safe reactors rely on nature to keep them cool|author=David Baurac}}</ref>

The SFR reactor concept is cooled by liquid [[sodium]] and fueled by a metallic alloy of uranium and [[plutonium]] or [[spent nuclear fuel]], the "nuclear waste" of [[light water reactor]]s. The SFR fuel is contained in steel cladding with liquid sodium filling in the space between the clad elements which make up the fuel assembly. One of the design challenges of an SFR is the risks of handling sodium, which reacts explosively if it comes into contact with water. However, the use of liquid metal instead of water as coolant allows the system to work at atmospheric pressure, reducing the risk of leakage.

The European Sustainable Nuclear Industrial Initiative is funding three Generation IV reactor systems, one of which is a sodium-cooled fast reactor, called ''[[ASTRID (reactor)|ASTRID]]'', Advanced Sodium Technical Reactor for Industrial Demonstration, [[Areva]], [[Commissariat à l'énergie atomique et aux énergies alternatives|CEA]] and [[Électricité de France|EDF]] are leading the design with British collaboration.<ref>{{cite web |url=http://www.power-eng.com/articles/2010/11/areva--cea-secure.html |title=Areva, CEA secure EUR650m funding to develop ASTRID sodium-cooled Generation IV reactor 11/11/2010}}</ref><ref>{{cite web |url=http://www.powermag.com/uk-and-france-sign-landmark-civil-nuclear-cooperation-agreement/ |title=UK and France Sign Landmark Civil Nuclear Cooperation Agreement 02/22/2012 . POWERnews}}</ref> Astrid will be rated about 600 MWe and is proposed to be built in France, near to the [[Phénix]] reactor. A final decision in construction is to be made in 2019<ref name="euronuclear.org"/>

The [[China|PRC]]'s first commercial-scale, 800 MWe, fast neutron reactor, to be situated near [[Sanming]] in [[Fujian province]] will be a SFR. In 2009 an agreement was signed that would entail the Russian [[BN-800 reactor]] design to be sold to the PRC once it is completed, this would be the first time commercial-scale fast neutron reactors have ever been exported.<ref>{{cite web |url=http://www.world-nuclear-news.org/C-Joint_venture_launched_for_Chinese_fast_reactor-3004104.html |title=Joint venture launched for Chinese fast reactor}}</ref> The BN-800 reactor became operational in 2014.

The 400 MWe [[Fast Flux Test Facility]] operated successfully for ten years at the Hanford site in Washington State.

The 20 MWe [[EBR II]] operated successfully for over thirty years at the Idaho National Laboratory, until it was shut down in 1994.

GE Hitachi's [[PRISM (reactor)|PRISM]] reactor is an SFR with the primary purpose of reducing the half lives of the fissionable elements present in used nuclear fuel while generating electricity largely as a by-product.

==== Lead-cooled fast reactor (LFR) ====
[[File:Lead-Cooled Fast Reactor Schemata.svg|right|thumb|Lead-Cooled Fast Reactor (LFR)]]
{{Main article|Lead-cooled fast reactor}}
{{See also|MYRRHA}}
The '''lead-cooled fast reactor'''<ref name="Roadmap">{{cite journal|year=2002 |title=A Technology Roadmap for Generation IV Nuclear Energy Systems |last=US DOE Nuclear Energy Research Advisory Committee |volume=GIF-002-00 |url=http://nuclear.energy.gov/genIV/documents/gen_iv_roadmap.pdf |deadurl=yes |archiveurl=https://web.archive.org/web/20071129121214/http://nuclear.energy.gov/genIV/documents/gen_iv_roadmap.pdf |archivedate=2007-11-29 |df= }}</ref> features a fast-neutron-spectrum [[lead]] or [[lead]]/[[bismuth]] [[eutectic]] ([[Lead-bismuth eutectic|LBE]]) liquid-metal-cooled reactor with a closed [[Nuclear fuel cycle|fuel cycle]]. Options include a range of plant ratings, including a "battery" of 50 to 150 MW of electricity that features a very long refueling interval, a modular system rated at 300 to 400 MW, and a large monolithic plant option at 1,200 MW (The term ''battery'' refers to the long-life, factory-fabricated core, not to any provision for electrochemical energy conversion). The fuel is metal or nitride-based containing [[Fertile material|fertile uranium]] and [[transuranic]]s. The LFR is cooled by natural [[convection]] with a reactor outlet coolant temperature of 550 °C, possibly ranging up to 800 °C with advanced materials. The higher temperature enables the production of [[Thermochemical cycle|hydrogen by thermochemical processes]].

The European Sustainable Nuclear Industrial Initiative is funding three Generation IV reactor systems, one of which is a lead-cooled fast reactor that is also an [[Subcritical reactor|accelerator-driven sub-critical]] reactor, called ''[[MYRRHA]]'', 100 MW(t), which will be built in [[Belgium]] with construction expected to begin after 2014 and the industrial scale version, known as ''Alfred'', slated to be constructed sometime after 2017. A reduced-power model of Myrrha called ''Guinevere'' was started up at [[Mol, Belgium|Mol]] in March 2009.<ref name="euronuclear.org"/> In 2012 the research team reported that Guinevere was operational.<ref>{{cite news|last1=Hellemans|first1=Alexander|title=Reactor-Accelerator Hybrid Achieves Successful Test Run|url=http://news.sciencemag.org/physics/2012/01/reactor-accelerator-hybrid-achieves-successful-test-run|accessdate=29 December 2014|work=Science Insider|date=12 January 2012}}</ref>

Two other lead-cooled fast reactors under development are the SVBR-100, a modular 100 MWe lead-bismuth cooled fast neutron reactor concept designed by OKB [[Gidropress]] in Russia and the [[BREST (Reactor)|BREST-OD-300]] (Lead-cooled fast reactor) 300 MWe, to be developed after the SVBR-100, and built over 2016-20, it will dispense with the [[Uranium-238|fertile blanket]] around the core and will supersede the sodium cooled [[BN-600 reactor]] design, to purportedly give enhanced proliferation resistance.<ref name="powertecrussia.com"/>

== Advantages and disadvantages ==
Relative to current nuclear power plant technology, the claimed benefits for 4th generation reactors include:
* Nuclear waste that remains radioactive for a few centuries instead of millennia<ref>{{cite web |title=Strategies to Address Global Warming |url=http://www.columbia.edu/~jeh1/mailings/2009/20090713_Strategies.pdf}}</ref>
* 100–300 times more energy yield from the same amount of nuclear fuel<ref>{{cite web |title=4th Generation Nuclear Power |url=http://www.ossfoundation.us/projects/energy/nuclear}}</ref>
* Broader range of fuels, and even unencapsulated raw fuels (non-pebble [[Molten Salt Reactor|MSR]], [[Liquid fluoride thorium reactor|LFTR]]).
* In some reactors, the ability to consume existing nuclear waste in the production of electricity, that is, a Closed [[nuclear fuel cycle]]. This strengthens the argument to deem [[nuclear power as renewable energy]].
* Improved operating safety features, such as (depending on design) avoidance of pressurized operation, automatic passive (unpowered, uncommanded) reactor shutdown, avoidance of water cooling and the associated risks of loss of water (leaks or boiling) and hydrogen generation/explosion and contamination of coolant water.

Nuclear reactors do not emit CO2 during operation, although like all [[low carbon power]] sources, the mining and construction phase can result in CO2 emissions, if energy sources which are not carbon neutral (such as fossil fuels), or CO2 emitting cements are used during the construction process.
A 2012 [[Yale University]] review published in the Journal of Industrial Ecology analyzing {{CO2}} [[life cycle assessment]] (LCA) emissions from [[nuclear power]] determined that:<ref name="Warner + Heath, JoIE">Warner, Ethan S.; Heath, Garvin A. [http://onlinelibrary.wiley.com/doi/10.1111/j.1530-9290.2012.00472.x/full Life Cycle Greenhouse Gas Emissions of Nuclear Electricity Generation: Systematic Review and Harmonization], ''Journal of Industrial Ecology'', [[Yale University]], published online April 17, 2012, {{doi|10.1111/j.1530-9290.2012.00472.x}}</ref>
{{Quote|The collective LCA literature indicates that life cycle [[Greenhouse gas|GHG]] [greenhouse gas] emissions from nuclear power are only a fraction of traditional fossil sources and comparable to renewable technologies.}}
Although the paper primarily dealt with data from [[Generation II reactor]]s, and did not analyze the {{CO2}} emissions by 2050 of the presently under construction [[Generation III reactor]]s, it did summarize the Life Cycle Assessment findings of in development reactor technologies.{{Quote|FBRs ['[[Fast Breeder Reactor]]s'] have been evaluated in the LCA literature. The limited literature that evaluates this potential future technology reports [[median]] life cycle GHG emissions... similar to or lower than LWRs [Gen II [[light water reactor]]s] and purports to consume little or no [[uranium market|uranium ore]].}}

A specific risk of the sodium-cooled fast reactor is related to using metallic sodium as a coolant. In case of a breach, sodium explosively reacts with water. Fixing breaches may also prove dangerous, as the cheapest noble gas [[argon]] is also used to prevent sodium oxidation. Argon, like helium, can displace oxygen in the air and can pose [[hypoxia (environmental)|hypoxia]] concerns, so workers may be exposed to this additional risk. This is a pertinent problem as demonstrated by the events at the [[LMFBR|loop type]] [[Monju Nuclear Power Plant|Prototype Fast Breeder Reactor Monju]] at Tsuruga, Japan.<ref>{{cite news |title=Japan Strains to Fix a Reactor Damaged Before Quake |url=https://www.nytimes.com/2011/06/18/world/asia/18japan.html | work=The New York Times | first=Hiroko |last=Tabuchi |date=17 June 2011}}</ref>
Using lead or molten salts mitigates this problem by making the coolant less reactive and allowing a high freezing temperature and low pressure in case of a leak. Disadvantages of lead compared to sodium are much higher viscosity, much higher density, lower heat capacity, and more radioactive neutron activation products.

In many cases, there is already a large amount of experience built up with numerous proof of concept Gen IV designs. For example, the reactors at [[Fort St. Vrain Generating Station]] and [[HTR-10]] are similar to the proposed Gen IV [[VHTR]] designs, and the [[LMFBR|pool type]] [[EBR-II]], [[Phénix]] and [[BN-600]] reactor are similar to the proposed pool type Gen IV Sodium Cooled Fast reactors being designed.

== Table of designs ==

{| class=wikitable
|+ Summary of designs for generation IV reactors<ref>https://www.gen-4.org/gif/upload/docs/application/pdf/2013-09/gif_rd_outlook_for_generation_iv_nuclear_energy_systems.pdf</ref>
|-
! System
! Neutron Spectrum
! Coolant
! Temperature (°C)
! Fuel Cycle
! Size (MW)
!Example developers
|-
| [[Very-high-temperature reactor|VHTR]]
| Thermal
| Helium
| 900–1000
| Open
| 250–300
|[[Japan Atomic Energy Agency|JAEA]] ([[High-temperature engineering test reactor|HTTR]]), [[Tsinghua University]] ([[HTR-10]]), [[X-energy]]<ref name="energy.gov">{{cite web|title=Energy Department Announces New Investments in Advanced Nuclear Power Reactors...|url=https://www.energy.gov/articles/energy-department-announces-new-investments-advanced-nuclear-power-reactors-help-meet|website=[[United States Department of Energy|US Department of Energy]]|accessdate=16 January 2016}}</ref>
|-
| [[Sodium-cooled fast reactor|SFR]]
| Fast
| Sodium
| 550
| Closed
| 30–150, 300–1500, 1000–2000
|[[TerraPower]] ([[Traveling wave reactor|TWR]]), [[Toshiba]] ([[Toshiba 4S|4S]]), [[GE Hitachi Nuclear Energy]] ([[PRISM (reactor)|PRISM]])
|-
| [[Supercritical water reactor|SCWR]]
| Thermal or fast
| Water
| 510–625
| Open or closed
| 300–700, 1000–1500
|
|-
| [[Gas-cooled fast reactor|GFR]]
| Fast
| Helium
| 850
| Closed
| 1200
|[[Energy Multiplier Module]]
|-
| [[Lead-cooled fast reactor|LFR]]
| Fast
| Lead
| 480–800
| Closed
| 20–180, 300–1200, 600–1000
|
|-
| [[Molten salt reactor|MSR]]
| Fast or thermal
| Fluoride or chloride salts
| 700–800
| Closed
| 250, 1000
|[[Seaborg Technologies]], [[TerraPower]], [[Stable Salt Reactor|Moltex Energy]], [[Flibe Energy]] ([[Liquid fluoride thorium reactor|LFTR]]), [[Transatomic Power]], Thorium Tech Solution ([[Fuji Molten Salt Reactor|FUJI MSR]]), Terrestrial Energy ([[IMSR]]), [[Southern Company Services|Southern Company]]<ref name="energy.gov"/>, [[Elysium Industries]]<ref>http://www.elysiumindustries.com/</ref>
|-
| [[Dual fluid reactor|DFR]]
| Fast
| Lead
| 1000
| Closed
| 500–1500
| Institute for Solid-State Nuclear Physics<ref name=ifk>{{cite web |url=https://festkoerper-kernphysik.de/dfr.pdf |title=Dual Fluid Reactor - IFK |date=2013-06-16 |website=festkoerper-kernphysik.de |publisher= Institut für Festkörper-Kernphysik |format=PDF |location=Berlin, Germany |access-date=2017-08-28}}</ref>, [[Aristos Power]] <ref name=HSR>{{|url=http://aristospower.tk |title=Hard Spectrum Reactor - HSR</ref>
|}

== See also ==
{{portal|Energy|Nuclear technology}}
{{colbegin}}
* [[Nuclear reactor]]
* [[Nuclear material]]
* [[Nuclear physics]]
* [[List of reactor types#Reactor types|List of reactor types]]
* [[Generation II reactor]]
* [[Generation III reactor]]
* [[Integral Fast Reactor]]
* [[Liquid fluoride thorium reactor]]
* [[Breeder reactor]]
* [[Small modular reactor]]
{{colend}}

==References==
{{Reflist|30em}}

== External links ==
* [https://inlportal.inl.gov/portal/server.pt?open=514&objID=1361&parentname=CommunityPage&parentid=10&mode=2&in_hi_userid=200&cached=true Article from Idaho National Laboratory detailing some current efforts at developing Gen. IV reactors.]
* [http://www.gen-4.org/ Generation IV International Forum (GIF)]
* [https://web.archive.org/web/20070205115654/http://nuclear.energy.gov/genIV/neGenIV1.html U.S. Department of Energy Office of Nuclear Energy, Science and Technology]
* [https://web.archive.org/web/20060512033030/http://www.engr.utk.edu/nuclear/colloquia/slides/Gen%20IV%20U-Tenn%20Presentation.pdf Gen IV presentation]
* [http://www.ecology.at/ecology/files/pr577_1.pdf Science or Fiction - Is there a Future for Nuclear?] (Nov. 2007) - A publication from the Austrian [[Ecology Institute (Austria)|Ecology Institute]] about 'Generation IV' and Fusion reactors.
* {{cite web |url=http://memagazine.asme.org/Articles/2011/December/Nuclear_Power_After_Fukushima.cfm |title=Nuclear Power After Fukushima |author=Gail H. Marcus |date=December 2011 |work=Mechanical Engineering (the magazine of [[ASME]]) |accessdate=23 January 2012}} "In the wake of a severe plant accident, advanced reactor designs are getting renewed attention."
* [http://www.itheo.org/ International Thorium Energy Organisation - www.IThEO.org]
* [http://www.ithec.org/ International Thorium Energy Committee - iThEC]

{{Nuclear fission reactors}}

[[Category:Nuclear power reactor types]]
[[Category:Idaho National Laboratory]]

Benutzer:Snackroeg/Kernreaktoren der Generation 5

2018-02-25T05:57:13Z

Boundarylayer:

{{update|date=October 2017}}
[[File:GenIVRoadmap-en.svg|thumb|480px|Nuclear Energy Systems Deployable no later than 2030 and offering significant advances in sustainability, safety and reliability, and economics]]

'''Generation IV reactors''' ('''Gen IV''') are a set of [[nuclear reactor]] designs currently being researched for commercial applications by the Generation IV International Forum, with [[Technology readiness level]]s varying between the level requiring a demonstration, to economical competitive implementation.<ref>{{Cite journal|last=Locatelli|first=Giorgio|last2=Mancini|first2=Mauro|last3=Todeschini|first3=Nicola|date=2013-10-01|title=Generation IV nuclear reactors: Current status and future prospects|url=http://www.sciencedirect.com/science/article/pii/S0301421513006083|journal=Energy Policy|volume=61|pages=1503–1520|doi=10.1016/j.enpol.2013.06.101}}</ref> They are motivated by a variety of goals including improved safety, sustainability, efficiency, and cost.

The most developed Gen IV reactor design, the [[sodium fast reactor]], has received the greatest share of funding over the years, with the principle Gen IV aspect of the design, relating in largest part to the development of a sustainable [[nuclear fuel cycle|closed fuel cycle]] for the reactor. Amongst nuclear engineers the [[molten-salt reactor]], the least developed and funded technology, is considered as potentially having the greatest [[inherent safety]] of the six models.<ref>[https://www.scientificamerican.com/article/can-sodium-save-nuclear-power/ Can Sodium Save Nuclear Power? Scientific American]</ref><ref>{{cite journal |last1=Moir |first1=Ralph |last2=Teller |first2=Edward |year=2005 |title=Thorium-Fueled Underground Power Plant Based on Molten Salt Technology |journal=Nuclear Technology |volume=151 |issue=3 |pages=334–340 |publisher=[[American Nuclear Society]] |url=http://www.new.ans.org/pubs/journals/nt/a_3655 |accessdate=March 22, 2012 }}</ref>

The majority of the 6 designs are generally not expected to be available for commercial construction until 2020–30.<ref name="Generation IV">[http://www.world-nuclear.org/info/Nuclear-Fuel-Cycle/Power-Reactors/Generation-IV-Nuclear-Reactors/]</ref> Presently the majority of reactors in operation around the world are considered [[Generation II reactor|second generation reactor]] systems, as the vast majority of the [[Nuclear reactor#Classification by generation|first generation]] systems were retired some time ago, and there are only a dozen or so [[Generation III reactor]]s in operation as of 2014.
[[Nuclear reactor#Generation V+ reactors|Generation V reactors]] refer to reactors that are purely theoretical and are therefore not yet considered feasible in the short term, resulting in limited [[R&D]] funding.

== History ==
The Generation IV International Forum (GIF) is "a co-operative international endeavour which was set up to carry out the research and development needed to establish the feasibility and performance capabilities of the next generation nuclear energy systems."<ref>{{Cite web|url=https://www.gen-4.org/gif/jcms/c_9260/public|title=GIF Portal - Home - Public|website=www.gen-4.org|access-date=2016-07-25}}</ref> It was founded in 2001. Currently active members of the Generation IV International Forum (GIF) include: [[Australia]], [[Canada]], [[China]], the [[European Atomic Energy Community]] (Euratom), [[France]], [[Japan]], [[Russia]], [[South Africa]], [[South Korea]], [[Switzerland]], and the [[United States]]. The non-active members are [[Argentina]], [[Brazil]], and the [[United Kingdom]].<ref name="gen-4">{{cite web|url=https://www.gen-4.org/gif/jcms/c_9492/members|title=GIF Membership|website=gen-4.org|accessdate=28 October 2014}}</ref> Switzerland joined in 2002, Euratom in 2003, and China and Russia in 2006. The remaining countries (excluding Australia) were founding members.<ref name="gen-4" />

The 36th GIF meeting in [[Brussels]] was held in November 2013.<ref>{{cite web|url=https://www.energy.gov/ne/articles/generation-iv-international-forum-updates-technology-roadmap-and-builds-future|title=generation IV international forum updates technology roadmap and builds future. DOE}}</ref><ref>{{cite web|url=http://events.r20.constantcontact.com/register/event?llr=mscrkjkab&oeidk=a07e7melf609716b2c6 |title=The Generation IV international forum holds their 36th meeting on Monday 18th Nov 2013 in Brussels. }}{{dead link|date=January 2017 |bot=InternetArchiveBot |fix-attempted=yes }}</ref> The ''Technology Roadmap Update for Generation IV Nuclear Energy Systems'' was published in January 2014 which details R&D objectives for the next decade.<ref>[https://web.archive.org/web/20140625102915/https://www.gen-4.org/gif/upload/docs/application/pdf/2014-03/gif-tru2014.pdf Technology Roadmap Update for Generation IV Nuclear Energy Systems]</ref> A breakdown of the reactor designs being researched by each forum member has been made available.<ref>[https://web.archive.org/web/20140708023538/https://www.gen-4.org/gif/upload/docs/application/pdf/2014-03/gif_overview_presentation_v9_final3_web.pdf Generation IV International Forum, overview, John E. Kelly, page 15]</ref>

[[Nuclear power in Australia|Australia]] joined the forum in 2016.<ref>https://archive.is/20160907131656/https://www.gen-4.org/gif/jcms/c_71564/australia-joins-the-generation-iv-international-forum</ref>

In January 2018, it was reported that "the first installation of the pressure vessel cover of the world's first Gen IV reactor" had been completed on the [[HTR-PM]].<ref>http://www.world-nuclear-news.org/NN-First-HTR-PM-vessel-head-in-place-0401185.html</ref>

== Reactor types ==
Many reactor types were considered initially; however, the list was downsized to focus on the most promising technologies and those that could most likely meet the goals of the Gen IV initiative.<ref name="Generation IV"/> Three systems are nominally [[thermal reactor]]s and four are [[fast reactor]]s. The Very High Temperature Reactor (VHTR) is also being researched for potentially providing high quality process heat for [[thermochemical cycle|hydrogen production]]. The fast reactors offer the possibility of burning [[actinides]] to further reduce waste and of being able to "[[breeder reactor|breed more fuel]]" than they consume. These systems offer significant advances in sustainability, safety and reliability, economics, proliferation resistance (depending on perspective) and physical protection.

=== Thermal reactors ===
A [[Thermal-neutron reactor|thermal reactor]] is a [[nuclear reactor]] that uses slow or [[thermal neutrons]]. A [[neutron moderator]] is used to slow the [[neutron]]s emitted by fission to make them more likely to be captured by the fuel.

==== Very-high-temperature reactor (VHTR) ====
[[File:Very High Temperature Reactor.svg|right|thumb|Very-High-Temperature Reactor (VHTR)]]
{{Main article|Very high temperature reactor}}
{{see also|Fort St. Vrain Generating Station|High-temperature engineering test reactor|HTR-10}}
The '''very high temperature reactor''' concept uses a [[graphite]]-moderated core with a once-through [[uranium]] fuel cycle, using helium or molten salt as the [[Very high temperature reactor#Coolant|coolant]]. This reactor design envisions an outlet temperature of 1,000 °C. The reactor core can be either a prismatic-block or a [[pebble bed reactor]] design. The high temperatures enable applications such as process heat or [[hydrogen]] production via the thermochemical [[Sulfur-iodine cycle|iodine-sulfur]] process. It would also be [[Passive nuclear safety|passively safe]].

The planned construction of the first VHTR, the South African PBMR ([[pebble bed modular reactor]]), lost government funding in February, 2010.<ref>[http://www.powergenworldwide.com/index/display/articledisplay/6322207443/articles/power-engineering-international/volume-18/Issue_3/regulars/world-news/INTERNATIONAL.html South Africa to stop funding Pebble Bed nuclear reactor] {{webarchive|url=https://web.archive.org/web/20100909172743/http://www.powergenworldwide.com/index/display/articledisplay/6322207443/articles/power-engineering-international/volume-18/Issue_3/regulars/world-news/INTERNATIONAL.html |date=2010-09-09 }}</ref> A pronounced increase of costs and concerns about possible unexpected technical problems had discouraged potential investors and customers.

The [[Peoples Republic of China]] began construction of a 200-MW High Temperature Pebble bed reactor in 2012 as a successor to its [[HTR-10]].<ref>[http://www.nucnet.org/all-the-news/2013/01/07/china-begins-construction-of-first-generation-iv-htr-pm-unit Nucnet Report: 'China Begins Construction of First Generation IV HTR-PM Unit', 7 January 2013]</ref>

Also in 2012, as part of the [[Next Generation Nuclear Plant]] competition, [[Idaho National Laboratory]] approved a design similar to [[Areva]]'s prismatic block [http://us.areva.com/EN/home-3225/areva-inc-areva-htgr.html Antares reactor] as the chosen [[HTGR]] to be deployed as a prototype by 2021. It was in competition with [[General Atomics]]' [[Gas turbine modular helium reactor]] and [[Westinghouse Electric Company|Westinghouse]]'s [[Pebble Bed Modular Reactor]].<ref name="World nuclear news">{{cite web|url=http://www.world-nuclear-news.org/NN-Areva_modular_reactor_selected_for_NGNP_development-1502124.html|title=INL approves Antares design}}</ref>

[[X-energy]] was awarded a five-year $53M U.S. Department of Energy Advanced Reactor Concept Cooperative Agreement award to advance elements of their reactor development.<ref>[https://www.x-energy.com/doe-partnership]</ref>
The [[X-energy#Reactor Design|Xe-100]] is a pebble-bed modular reactor and will generate 200-MWt and approximately 76-MWe. The standard Xe-100 "four-pack" plant generates approximately 300-MWe and will fit on as few as 13 acres. All of the components for the Xe-100 will be road-transportable, and will be installed, rather than constructed, at the project site to streamline construction.<ref name="X-energy">{{cite web|url=https://www.x-energy.com/}}</ref>

==== Molten-salt reactor (MSR) ====
[[File:Molten Salt Reactor.svg|right|thumb|Molten Salt Reactor (MSR)]]
{{Main article|Molten salt reactor}}
{{see also|Liquid fluoride thorium reactor}}
A '''molten salt reactor'''<ref name="Roadmap"/> is a type of [[nuclear reactor]] where the primary [[coolant]], or even the fuel itself is a molten salt mixture. There have been many designs put forward for this type of reactor and a few prototypes built. The early concepts and many current ones rely on [[nuclear fuel]], perhaps [[uranium tetrafluoride]] (UF4) or [[thorium tetrafluoride]] (ThF4), dissolved in molten [[fluoride]] salt. The fluid would reach [[Nuclear reactor physics#Criticality|criticality]] by flowing into a core where [[graphite]] would serve as the [[neutron moderator|moderator]]. Many current concepts rely on fuel that is dispersed in a graphite matrix with the molten salt providing low pressure, high temperature cooling.

The Gen IV MSR is more accurately termed an [[epithermal neutron|epithermal reactor]] than a thermal reactor due to the average speed of the neutrons that would cause the fission events within its fuel being faster than [[thermal neutron]]s.<ref>{{cite web |url=https://inlportal.inl.gov/portal/server.pt?open=514&objID=1361&parentname=CommunityPage&parentid=10&mode=2&in_hi_userid=200&cached=true |title=Idaho National Laboratory detailing some current efforts at developing Gen. IV reactors}}</ref>

The principle of a MSR can be used for thermal, epithermal and fast reactors. Since 2005 the focus has moved towards a fast spectrum MSR (MSFR).<ref>H. Boussier, S. Delpech, V. Ghetta et Al. : The Molten Salt Reactor (MSR) in Generation IV: Overview and Perspectives, GIF SYMPOSIUM PROCEEDINGS/2012 ANNUAL REPORT, NEA No. 7141, pp95 [https://www.gen-4.org/gif/jcms/c_44720/annual-reports]
</ref>

While most MSR designs being pursued are largely derived from the 1960s [[Molten-Salt Reactor Experiment]](MSRE), variants of molten salt technology include the conceptual ''[[Dual fluid reactor]]'' which is being designed with lead as a cooling medium but molten salt fuel, commonly as the metal chloride e.g. [[Plutonium(III) chloride]], to aid in greater "nuclear waste" closed-fuel cycle capabilities.
Other notable approaches differing substantially from MSRE include the ''[[Stable Salt Reactor]]''(SSR) concept promoted by MOLTEX, which encases the molten salt in hundreds of the common solid [[fuel rod]]s that are already well established in the nuclear industry. This latter British design was found to be the most competitive for [[Small modular reactor]] development by a British-based consultancy firm ''Energy Process Development'' in 2015.<ref>[http://www.daretothink.org/europe-moltex-stable-salt-reactor/ Europe: Moltex’ Stable Salt Reactor]</ref><ref>[http://analysis.nuclearenergyinsider.com/moltex-energy-sees-uk-canada-smr-licensing-springboard-asia Moltex Energy sees UK, Canada SMR licensing as springboard to Asia Jun 28, 2016]</ref>

Another notable feature of the MSR is the possibility of a [[Thermal-neutron reactor|thermal spectrum]] nuclear [[Nuclear fuel cycle#Fuel cycles|waste-burner]]. Conventionally only fast spectrum reactors have been considered viable for [[Nuclear fuel cycle#Minor actinides recycling|utilization or reduction]] of the [[Spent nuclear fuel|spent nuclear stockpiles]]. The conceptual viability of a thermal waste-burner was first shown in a whitepaper by [[Seaborg Technologies]] spring 2015.<ref name="Seaborg Whitepaper 2015">{{cite web|url=https://seaborg.dk/s/Seaborg-whitepaper-2015.pdf|title=Thermal MSR waste burner benchmark}}</ref> Thermal waste-burning was achieved by replacing a fraction of the [[uranium]] in the spent nuclear fuel with [[thorium]]. The net production rate of [[transuranium element]] (e.g. [[plutonium]] and [[americium]]) is reduced below the consumption rate, thus reducing the magnitude of the [[Radioactive waste|nuclear storage problem]]. Without the [[nuclear proliferation]] concerns and other [[Fast-neutron reactor#Disadvantages|technical issues]] associated with a [[Fast-neutron reactor|fast reactor]].

==== Supercritical-water-cooled reactor (SCWR) ====
[[File:Supercritical-Water-Cooled Reactor.svg|right|thumb|Supercritical-Water-Cooled Reactor (SCWR)]]
{{Main article|Supercritical water reactor}}
The '''supercritical water reactor''' (SCWR)<ref name="Roadmap"/> is a [[reduced moderation water reactor]] concept that, due to the average speed of the neutrons that would cause the fission events within the fuel being faster than [[thermal neutron]]s, it is more accurately termed an [[epithermal neutron|epithermal reactor]] than a thermal reactor. It uses [[supercritical fluid|supercritical water]] as the working fluid. SCWRs are basically [[light water reactor]]s (LWR) operating at higher pressure and temperatures with a direct, once-through heat exchange cycle. As most commonly envisioned, it would operate on a direct cycle, much like a boiling water reactor ([[BWR]]), but since it uses supercritical water (not to be confused with [[Critical mass (nuclear)|critical mass]]) as the working fluid, it would have only one water phase present, which makes the supercritical heat exchange method more similar to a pressurized water reactor ([[Pressurized water reactor|PWR]]). It could operate at much higher temperatures than both current PWRs and BWRs.

Supercritical water-cooled reactors (SCWRs) are promising advanced nuclear systems because of their high [[thermal efficiency]] (i.e., about 45% vs. about 33% efficiency for current LWRs) and considerable plant simplification.

The main mission of the SCWR is generation of low-cost [[electricity]]. It is built upon two proven technologies, LWRs, which are the most commonly deployed power generating reactors in the world, and superheated [[fossil fuel]] fired [[boiler]]s, a large number of which are also in use around the world. The SCWR concept is being investigated by 32 organizations in 13 countries.{{citation needed|date=October 2012}}

Because SCWRs are water reactors they share the steam explosion and radioactive steam release hazards of BWRs and LWRs as well as the need for extremely expensive heavy duty pressure vessels, pipes, valves, and pumps. These shared problems are inherently more severe for SCWRs due to operation at higher temperatures.

A SCWR Design under development is the [[VVER]]-1700/393 (VVER-SCWR or VVER-SKD) — a Russian Supercritical-water-cooled reactor with double-inlet-core and a [[breeder reactor|breeding ratio]] of 0.95.<ref name="powertecrussia.com">{{cite web |url=http://www.powertecrussia.com/blog/tag/nuclear-power/ |title=Technology Developments & Plant Efficiency for the Russian Nuclear Power Generation Market Wednesday |date=March 24, 2010}}</ref>

=== Fast reactors ===
A [[Fast-neutron reactor|fast reactor]] directly uses the fast neutrons emitted by fission, without moderation. Unlike thermal neutron reactors, fast neutron reactors can be configured to "'''burn'''", or fission, all [[actinides]], and given enough time, therefore drastically reduce the actinides fraction in [[spent nuclear fuel]] produced by the present world fleet of thermal neutron [[light water reactor]]s, thus closing the [[nuclear fuel cycle]]. Alternatively, if configured differently, they can also [[breeder reactor|'''breed''']] more actinide fuel than they consume.

==== Gas-cooled fast reactor (GFR) ====
[[File:Gas-Cooled Fast Reactor Schemata.svg|right|thumb|Gas-Cooled Fast Reactor (GFR)]]
{{Main article|Gas-cooled fast reactor}}
The '''gas-cooled fast reactor''' (GFR)<ref name="Roadmap"/> system features a fast-neutron spectrum and closed fuel cycle for efficient conversion of [[Fertile material|fertile uranium]] and management of actinides. The reactor is [[helium]]-cooled and with an outlet temperature of 850 °C it is an evolution of the [[very-high-temperature reactor]] (VHTR) to a more sustainable fuel cycle. It will use a direct [[Brayton cycle]] [[Closed-cycle gas turbine|gas turbine]] for high thermal efficiency. Several fuel forms are being considered for their potential to operate at very high temperatures and to ensure an excellent retention of [[Nuclear fission|fission]] products: composite [[ceramic]] fuel, advanced fuel particles, or ceramic clad elements of actinide compounds. Core configurations are being considered based on pin- or plate-based fuel assemblies or prismatic blocks.

The European Sustainable Nuclear Industrial Initiative is funding three Generation IV reactor systems, one of which is a gas-cooled fast reactor, called ''Allegro'', 100 MW(t), which will be built in a central or eastern European country with construction expected to begin in 2018.<ref name="euronuclear.org">{{cite web|url=https://www.euronuclear.org/1-information/news/Gen-IV.htm |title=The European Sustainable Nuclear Industrial Initiative (ESNII) will support three Generation IV reactor systems: a sodium-cooled fast reactor, or SFR, called ''Astrid'' that is proposed by France; a gas-cooled fast reactor, GFR, called ''Allegro'' supported by central and eastern Europe; and a lead-cooled fast reactor, LFR, technology pilot called ''Myrrha'' that is proposed by Belgium. |deadurl=yes |archiveurl=https://web.archive.org/web/20131009042600/http://euronuclear.org/1-information/news/Gen-IV.htm |archivedate=2013-10-09 |df= }}</ref> The central European [[Visegrád Group]] are committed to pursuing the technology.<ref>{{cite web |url=http://www.alphagalileo.org/ViewItem.aspx?ItemId=133111&CultureCode=en |title=The V4G4 Centre of Excellence for performing joint research, development and innovation in the field of Generation-4 (G4) nuclear reactors have been established. 20 July 2013 National Center for Nuclear Research (NCBJ)}}</ref> In 2013 German, British, and French institutes finished a 3-year collaboration study on the follow on industrial scale design, known as ''GoFastR''.<ref>{{cite web|url=http://www.ist-world.org/ProjectDetails.aspx?ProjectId=5cb8f3f283574cc6b2bdbf72533172d8 |title=the European Gas cooled Fast Reactor. |deadurl=yes |archiveurl=https://web.archive.org/web/20131213091046/http://www.ist-world.org/ProjectDetails.aspx?ProjectId=5cb8f3f283574cc6b2bdbf72533172d8 |archivedate=2013-12-13 |df= }}</ref> They were funded by the EU's 7th FWP [[framework programme]], with the goal of making a sustainable VHTR.<ref>{{cite web |url=http://www.2020-horizon.com/GOFASTR-European-Gas-Cooled-Fast-Reactor%28GOFASTR%29-s312.html |title=The GOFASTR research program}}</ref>

==== Sodium-cooled fast reactor (SFR) ====
[[File:Sodium-Cooled Fast Reactor Schemata.svg|right|thumb|Pool design Sodium-Cooled Fast Reactor (SFR)]]
{{Main article|Sodium-cooled fast reactor}}
{{see also|Prototype Fast Breeder Reactor|Experimental Breeder Reactor II|S-PRISM|BN-800 reactor|Toshiba 4S|CFR-600}}

In India, the [[Fast Breeder Test Reactor]] reached criticality in October 1985. In September 2002, fuel burn-up in the FBTR for the first time reached the 100,000 megawatt-days per metric ton uranium (MWd/MTU) mark. This is considered an important milestone in breeder reactor technology. Using the experience gained from the operation of the FBTR, the [[Prototype Fast Breeder Reactor]], a 500 MWe Sodium cooled fast reactor is being built at a cost of INR 5,677 crores (~US$900 million) and is expected to be critical by June 2018. The PFBR will be followed by six more Commercial Fast Breeder Reactors (CFBRs) of 600 MWe each.

The SFR<ref name="Roadmap"/> is a project that builds on two closely related existing projects, the liquid metal [[Breeder reactor#Fast breeder reactor|fast breeder reactor]] and the [[integral fast reactor]].

The goals are to increase the efficiency of uranium usage by [[breeder reactor|breeding]] plutonium and eliminating the need for [[transuranic]] isotopes ever to leave the site. The reactor design uses an unmoderated core running on [[fast neutron]]s, designed to allow any transuranic isotope to be consumed (and in some cases used as fuel). In addition to the benefits of removing the long [[half-life]] transuranics from the waste cycle, the SFR fuel expands when the reactor overheats, and the chain reaction automatically slows down. In this manner, it is passively safe.<ref>{{cite web |url=http://www.ne.anl.gov/About/hn/logos-winter02-psr.shtml|title=Passively safe reactors rely on nature to keep them cool|author=David Baurac}}</ref>

The SFR reactor concept is cooled by liquid [[sodium]] and fueled by a metallic alloy of uranium and [[plutonium]] or [[spent nuclear fuel]], the "nuclear waste" of [[light water reactor]]s. The SFR fuel is contained in steel cladding with liquid sodium filling in the space between the clad elements which make up the fuel assembly. One of the design challenges of an SFR is the risks of handling sodium, which reacts explosively if it comes into contact with water. However, the use of liquid metal instead of water as coolant allows the system to work at atmospheric pressure, reducing the risk of leakage.

The European Sustainable Nuclear Industrial Initiative is funding three Generation IV reactor systems, one of which is a sodium-cooled fast reactor, called ''[[ASTRID (reactor)|ASTRID]]'', Advanced Sodium Technical Reactor for Industrial Demonstration, [[Areva]], [[Commissariat à l'énergie atomique et aux énergies alternatives|CEA]] and [[Électricité de France|EDF]] are leading the design with British collaboration.<ref>{{cite web |url=http://www.power-eng.com/articles/2010/11/areva--cea-secure.html |title=Areva, CEA secure EUR650m funding to develop ASTRID sodium-cooled Generation IV reactor 11/11/2010}}</ref><ref>{{cite web |url=http://www.powermag.com/uk-and-france-sign-landmark-civil-nuclear-cooperation-agreement/ |title=UK and France Sign Landmark Civil Nuclear Cooperation Agreement 02/22/2012 . POWERnews}}</ref> Astrid will be rated about 600 MWe and is proposed to be built in France, near to the [[Phénix]] reactor. A final decision in construction is to be made in 2019<ref name="euronuclear.org"/>

The [[China|PRC]]'s first commercial-scale, 800 MWe, fast neutron reactor, to be situated near [[Sanming]] in [[Fujian province]] will be a SFR. In 2009 an agreement was signed that would entail the Russian [[BN-800 reactor]] design to be sold to the PRC once it is completed, this would be the first time commercial-scale fast neutron reactors have ever been exported.<ref>{{cite web |url=http://www.world-nuclear-news.org/C-Joint_venture_launched_for_Chinese_fast_reactor-3004104.html |title=Joint venture launched for Chinese fast reactor}}</ref> The BN-800 reactor became operational in 2014.

The 400 MWe [[Fast Flux Test Facility]] operated successfully for ten years at the Hanford site in Washington State.

The 20 MWe [[EBR II]] operated successfully for over thirty years at the Idaho National Laboratory, until it was shut down in 1994.

GE Hitachi's [[PRISM (reactor)|PRISM]] reactor is an SFR with the primary purpose of reducing the half lives of the fissionable elements present in used nuclear fuel while generating electricity largely as a by-product.

==== Lead-cooled fast reactor (LFR) ====
[[File:Lead-Cooled Fast Reactor Schemata.svg|right|thumb|Lead-Cooled Fast Reactor (LFR)]]
{{Main article|Lead-cooled fast reactor}}
{{See also|MYRRHA}}
The '''lead-cooled fast reactor'''<ref name="Roadmap">{{cite journal|year=2002 |title=A Technology Roadmap for Generation IV Nuclear Energy Systems |last=US DOE Nuclear Energy Research Advisory Committee |volume=GIF-002-00 |url=http://nuclear.energy.gov/genIV/documents/gen_iv_roadmap.pdf |deadurl=yes |archiveurl=https://web.archive.org/web/20071129121214/http://nuclear.energy.gov/genIV/documents/gen_iv_roadmap.pdf |archivedate=2007-11-29 |df= }}</ref> features a fast-neutron-spectrum [[lead]] or [[lead]]/[[bismuth]] [[eutectic]] ([[Lead-bismuth eutectic|LBE]]) liquid-metal-cooled reactor with a closed [[Nuclear fuel cycle|fuel cycle]]. Options include a range of plant ratings, including a "battery" of 50 to 150 MW of electricity that features a very long refueling interval, a modular system rated at 300 to 400 MW, and a large monolithic plant option at 1,200 MW (The term ''battery'' refers to the long-life, factory-fabricated core, not to any provision for electrochemical energy conversion). The fuel is metal or nitride-based containing [[Fertile material|fertile uranium]] and [[transuranic]]s. The LFR is cooled by natural [[convection]] with a reactor outlet coolant temperature of 550 °C, possibly ranging up to 800 °C with advanced materials. The higher temperature enables the production of [[Thermochemical cycle|hydrogen by thermochemical processes]].

The European Sustainable Nuclear Industrial Initiative is funding three Generation IV reactor systems, one of which is a lead-cooled fast reactor that is also an [[Subcritical reactor|accelerator-driven sub-critical]] reactor, called ''[[MYRRHA]]'', 100 MW(t), which will be built in [[Belgium]] with construction expected to begin after 2014 and the industrial scale version, known as ''Alfred'', slated to be constructed sometime after 2017. A reduced-power model of Myrrha called ''Guinevere'' was started up at [[Mol, Belgium|Mol]] in March 2009.<ref name="euronuclear.org"/> In 2012 the research team reported that Guinevere was operational.<ref>{{cite news|last1=Hellemans|first1=Alexander|title=Reactor-Accelerator Hybrid Achieves Successful Test Run|url=http://news.sciencemag.org/physics/2012/01/reactor-accelerator-hybrid-achieves-successful-test-run|accessdate=29 December 2014|work=Science Insider|date=12 January 2012}}</ref>

Two other lead-cooled fast reactors under development are the SVBR-100, a modular 100 MWe lead-bismuth cooled fast neutron reactor concept designed by OKB [[Gidropress]] in Russia and the [[BREST (Reactor)|BREST-OD-300]] (Lead-cooled fast reactor) 300 MWe, to be developed after the SVBR-100, and built over 2016-20, it will dispense with the [[Uranium-238|fertile blanket]] around the core and will supersede the sodium cooled [[BN-600 reactor]] design, to purportedly give enhanced proliferation resistance.<ref name="powertecrussia.com"/>

== Advantages and disadvantages ==
Relative to current nuclear power plant technology, the claimed benefits for 4th generation reactors include:
* Nuclear waste that remains radioactive for a few centuries instead of millennia<ref>{{cite web |title=Strategies to Address Global Warming |url=http://www.columbia.edu/~jeh1/mailings/2009/20090713_Strategies.pdf}}</ref>
* 100–300 times more energy yield from the same amount of nuclear fuel<ref>{{cite web |title=4th Generation Nuclear Power |url=http://www.ossfoundation.us/projects/energy/nuclear}}</ref>
* Broader range of fuels, and even unencapsulated raw fuels (non-pebble [[Molten Salt Reactor|MSR]], [[Liquid fluoride thorium reactor|LFTR]]).
* In some reactors, the ability to consume existing nuclear waste in the production of electricity, that is, a Closed [[nuclear fuel cycle]]. This strengthens the argument to deem [[nuclear power as renewable energy]].
* Improved operating safety features, such as (depending on design) avoidance of pressurized operation, automatic passive (unpowered, uncommanded) reactor shutdown, avoidance of water cooling and the associated risks of loss of water (leaks or boiling) and hydrogen generation/explosion and contamination of coolant water.

Nuclear reactors do not emit CO2 during operation, although like all [[low carbon power]] sources, the mining and construction phase can result in CO2 emissions, if energy sources which are not carbon neutral (such as fossil fuels), or CO2 emitting cements are used during the construction process.
A 2012 [[Yale University]] review published in the Journal of Industrial Ecology analyzing {{CO2}} [[life cycle assessment]] (LCA) emissions from [[nuclear power]] determined that:<ref name="Warner + Heath, JoIE">Warner, Ethan S.; Heath, Garvin A. [http://onlinelibrary.wiley.com/doi/10.1111/j.1530-9290.2012.00472.x/full Life Cycle Greenhouse Gas Emissions of Nuclear Electricity Generation: Systematic Review and Harmonization], ''Journal of Industrial Ecology'', [[Yale University]], published online April 17, 2012, {{doi|10.1111/j.1530-9290.2012.00472.x}}</ref>
{{Quote|The collective LCA literature indicates that life cycle [[Greenhouse gas|GHG]] [greenhouse gas] emissions from nuclear power are only a fraction of traditional fossil sources and comparable to renewable technologies.}}
Although the paper primarily dealt with data from [[Generation II reactor]]s, and did not analyze the {{CO2}} emissions by 2050 of the presently under construction [[Generation III reactor]]s, it did summarize the Life Cycle Assessment findings of in development reactor technologies.{{Quote|FBRs ['[[Fast Breeder Reactor]]s'] have been evaluated in the LCA literature. The limited literature that evaluates this potential future technology reports [[median]] life cycle GHG emissions... similar to or lower than LWRs [Gen II [[light water reactor]]s] and purports to consume little or no [[uranium market|uranium ore]].}}

A specific risk of the sodium-cooled fast reactor is related to using metallic sodium as a coolant. In case of a breach, sodium explosively reacts with water. Fixing breaches may also prove dangerous, as the cheapest noble gas [[argon]] is also used to prevent sodium oxidation. Argon, like helium, can displace oxygen in the air and can pose [[hypoxia (environmental)|hypoxia]] concerns, so workers may be exposed to this additional risk. This is a pertinent problem as demonstrated by the events at the [[LMFBR|loop type]] [[Monju Nuclear Power Plant|Prototype Fast Breeder Reactor Monju]] at Tsuruga, Japan.<ref>{{cite news |title=Japan Strains to Fix a Reactor Damaged Before Quake |url=https://www.nytimes.com/2011/06/18/world/asia/18japan.html | work=The New York Times | first=Hiroko |last=Tabuchi |date=17 June 2011}}</ref>
Using lead or molten salts mitigates this problem by making the coolant less reactive and allowing a high freezing temperature and low pressure in case of a leak. Disadvantages of lead compared to sodium are much higher viscosity, much higher density, lower heat capacity, and more radioactive neutron activation products.

In many cases, there is already a large amount of experience built up with numerous proof of concept Gen IV designs. For example, the reactors at [[Fort St. Vrain Generating Station]] and [[HTR-10]] are similar to the proposed Gen IV [[VHTR]] designs, and the [[LMFBR|pool type]] [[EBR-II]], [[Phénix]] and [[BN-600]] reactor are similar to the proposed pool type Gen IV Sodium Cooled Fast reactors being designed.

== Table of designs ==

{| class=wikitable
|+ Summary of designs for generation IV reactors<ref>https://www.gen-4.org/gif/upload/docs/application/pdf/2013-09/gif_rd_outlook_for_generation_iv_nuclear_energy_systems.pdf</ref>
|-
! System
! Neutron Spectrum
! Coolant
! Temperature (°C)
! Fuel Cycle
! Size (MW)
!Example developers
|-
| [[Very-high-temperature reactor|VHTR]]
| Thermal
| Helium
| 900–1000
| Open
| 250–300
|[[Japan Atomic Energy Agency|JAEA]] ([[High-temperature engineering test reactor|HTTR]]), [[Tsinghua University]] ([[HTR-10]]), [[X-energy]]<ref name="energy.gov">{{cite web|title=Energy Department Announces New Investments in Advanced Nuclear Power Reactors...|url=https://www.energy.gov/articles/energy-department-announces-new-investments-advanced-nuclear-power-reactors-help-meet|website=[[United States Department of Energy|US Department of Energy]]|accessdate=16 January 2016}}</ref>
|-
| [[Sodium-cooled fast reactor|SFR]]
| Fast
| Sodium
| 550
| Closed
| 30–150, 300–1500, 1000–2000
|[[TerraPower]] ([[Traveling wave reactor|TWR]]), [[Toshiba]] ([[Toshiba 4S|4S]]), [[GE Hitachi Nuclear Energy]] ([[PRISM (reactor)|PRISM]])
|-
| [[Supercritical water reactor|SCWR]]
| Thermal or fast
| Water
| 510–625
| Open or closed
| 300–700, 1000–1500
|
|-
| [[Gas-cooled fast reactor|GFR]]
| Fast
| Helium
| 850
| Closed
| 1200
|[[Energy Multiplier Module]]
|-
| [[Lead-cooled fast reactor|LFR]]
| Fast
| Lead
| 480–800
| Closed
| 20–180, 300–1200, 600–1000
|
|-
| [[Molten salt reactor|MSR]]
| Fast or thermal
| Fluoride or chloride salts
| 700–800
| Closed
| 250, 1000
|[[Seaborg Technologies]], [[TerraPower]], [[Stable Salt Reactor|Moltex Energy]], [[Flibe Energy]] ([[Liquid fluoride thorium reactor|LFTR]]), [[Transatomic Power]], Thorium Tech Solution ([[Fuji Molten Salt Reactor|FUJI MSR]]), Terrestrial Energy ([[IMSR]]), [[Southern Company Services|Southern Company]]<ref name="energy.gov"/>, [[Elysium Industries]]<ref>http://www.elysiumindustries.com/</ref>
|-
| [[Dual fluid reactor|DFR]]
| Fast
| Lead
| 1000
| Closed
| 500–1500
| Institute for Solid-State Nuclear Physics<ref name=ifk>{{cite web |url=https://festkoerper-kernphysik.de/dfr.pdf |title=Dual Fluid Reactor - IFK |date=2013-06-16 |website=festkoerper-kernphysik.de |publisher= Institut für Festkörper-Kernphysik |format=PDF |location=Berlin, Germany |access-date=2017-08-28}}</ref>, [[Aristos Power]] <ref name=HSR>{{|url=http://aristospower.tk |title=Hard Spectrum Reactor - HSR</ref>
|}

== See also ==
{{portal|Energy|Nuclear technology}}
{{colbegin}}
* [[Nuclear reactor]]
* [[Nuclear material]]
* [[Nuclear physics]]
* [[List of reactor types#Reactor types|List of reactor types]]
* [[Generation II reactor]]
* [[Generation III reactor]]
* [[Integral Fast Reactor]]
* [[Liquid fluoride thorium reactor]]
* [[Breeder reactor]]
* [[Small modular reactor]]
{{colend}}

==References==
{{Reflist|30em}}

== External links ==
* [https://inlportal.inl.gov/portal/server.pt?open=514&objID=1361&parentname=CommunityPage&parentid=10&mode=2&in_hi_userid=200&cached=true Article from Idaho National Laboratory detailing some current efforts at developing Gen. IV reactors.]
* [http://www.gen-4.org/ Generation IV International Forum (GIF)]
* [https://web.archive.org/web/20070205115654/http://nuclear.energy.gov/genIV/neGenIV1.html U.S. Department of Energy Office of Nuclear Energy, Science and Technology]
* [https://web.archive.org/web/20060512033030/http://www.engr.utk.edu/nuclear/colloquia/slides/Gen%20IV%20U-Tenn%20Presentation.pdf Gen IV presentation]
* [http://www.ecology.at/ecology/files/pr577_1.pdf Science or Fiction - Is there a Future for Nuclear?] (Nov. 2007) - A publication from the Austrian [[Ecology Institute (Austria)|Ecology Institute]] about 'Generation IV' and Fusion reactors.
* {{cite web |url=http://memagazine.asme.org/Articles/2011/December/Nuclear_Power_After_Fukushima.cfm |title=Nuclear Power After Fukushima |author=Gail H. Marcus |date=December 2011 |work=Mechanical Engineering (the magazine of [[ASME]]) |accessdate=23 January 2012}} "In the wake of a severe plant accident, advanced reactor designs are getting renewed attention."
* [http://www.itheo.org/ International Thorium Energy Organisation - www.IThEO.org]
* [http://www.ithec.org/ International Thorium Energy Committee - iThEC]

{{Nuclear fission reactors}}

[[Category:Nuclear power reactor types]]
[[Category:Idaho National Laboratory]]

Benutzer:Snackroeg/Kernreaktoren der Generation 5

2018-02-25T05:55:10Z

Boundarylayer:

{{update|date=October 2017}}
[[File:GenIVRoadmap-en.svg|thumb|480px|Nuclear Energy Systems Deployable no later than 2030 and offering significant advances in sustainability, safety and reliability, and economics]]

'''Generation IV reactors''' ('''Gen IV''') are a set of [[nuclear reactor]] designs currently being researched for commercial applications by the Generation IV International Forum, with [[Technology readiness level]]s varying between the level requiring a demonstration, to economical competitive implementation.<ref>{{Cite journal|last=Locatelli|first=Giorgio|last2=Mancini|first2=Mauro|last3=Todeschini|first3=Nicola|date=2013-10-01|title=Generation IV nuclear reactors: Current status and future prospects|url=http://www.sciencedirect.com/science/article/pii/S0301421513006083|journal=Energy Policy|volume=61|pages=1503–1520|doi=10.1016/j.enpol.2013.06.101}}</ref> They are motivated by a variety of goals including improved safety, sustainability, efficiency, and cost.

The most developed Gen IV reactor design, the [[sodium fast reactor]], has received the greatest share of funding over the years, with the principle Gen IV aspect of the design, relating in largest part to the development of a sustainable [[nuclear fuel cycle|closed fuel cycle]] for the reactor. Amongst nuclear engineers the [[molten-salt reactor]], the least developed and funded technology, is considered as having the greatest [[inherent safety]] of the six models.<ref>[https://www.scientificamerican.com/article/can-sodium-save-nuclear-power/ Can Sodium Save Nuclear Power? Scientific American]</ref><ref>{{cite journal |last1=Moir |first1=Ralph |last2=Teller |first2=Edward |year=2005 |title=Thorium-Fueled Underground Power Plant Based on Molten Salt Technology |journal=Nuclear Technology |volume=151 |issue=3 |pages=334–340 |publisher=[[American Nuclear Society]] |url=http://www.new.ans.org/pubs/journals/nt/a_3655 |accessdate=March 22, 2012 }}</ref>

The majority of the 6 designs are generally not expected to be available for commercial construction until 2020–30.<ref name="Generation IV">[http://www.world-nuclear.org/info/Nuclear-Fuel-Cycle/Power-Reactors/Generation-IV-Nuclear-Reactors/]</ref> Presently the majority of reactors in operation around the world are considered [[Generation II reactor|second generation reactor]] systems, as the vast majority of the [[Nuclear reactor#Classification by generation|first generation]] systems were retired some time ago, and there are only a dozen or so [[Generation III reactor]]s in operation as of 2014.
[[Nuclear reactor#Generation V+ reactors|Generation V reactors]] refer to reactors that are purely theoretical and are therefore not yet considered feasible in the short term, resulting in limited [[R&D]] funding.

== History ==
The Generation IV International Forum (GIF) is "a co-operative international endeavour which was set up to carry out the research and development needed to establish the feasibility and performance capabilities of the next generation nuclear energy systems."<ref>{{Cite web|url=https://www.gen-4.org/gif/jcms/c_9260/public|title=GIF Portal - Home - Public|website=www.gen-4.org|access-date=2016-07-25}}</ref> It was founded in 2001. Currently active members of the Generation IV International Forum (GIF) include: [[Australia]], [[Canada]], [[China]], the [[European Atomic Energy Community]] (Euratom), [[France]], [[Japan]], [[Russia]], [[South Africa]], [[South Korea]], [[Switzerland]], and the [[United States]]. The non-active members are [[Argentina]], [[Brazil]], and the [[United Kingdom]].<ref name="gen-4">{{cite web|url=https://www.gen-4.org/gif/jcms/c_9492/members|title=GIF Membership|website=gen-4.org|accessdate=28 October 2014}}</ref> Switzerland joined in 2002, Euratom in 2003, and China and Russia in 2006. The remaining countries (excluding Australia) were founding members.<ref name="gen-4" />

The 36th GIF meeting in [[Brussels]] was held in November 2013.<ref>{{cite web|url=https://www.energy.gov/ne/articles/generation-iv-international-forum-updates-technology-roadmap-and-builds-future|title=generation IV international forum updates technology roadmap and builds future. DOE}}</ref><ref>{{cite web|url=http://events.r20.constantcontact.com/register/event?llr=mscrkjkab&oeidk=a07e7melf609716b2c6 |title=The Generation IV international forum holds their 36th meeting on Monday 18th Nov 2013 in Brussels. }}{{dead link|date=January 2017 |bot=InternetArchiveBot |fix-attempted=yes }}</ref> The ''Technology Roadmap Update for Generation IV Nuclear Energy Systems'' was published in January 2014 which details R&D objectives for the next decade.<ref>[https://web.archive.org/web/20140625102915/https://www.gen-4.org/gif/upload/docs/application/pdf/2014-03/gif-tru2014.pdf Technology Roadmap Update for Generation IV Nuclear Energy Systems]</ref> A breakdown of the reactor designs being researched by each forum member has been made available.<ref>[https://web.archive.org/web/20140708023538/https://www.gen-4.org/gif/upload/docs/application/pdf/2014-03/gif_overview_presentation_v9_final3_web.pdf Generation IV International Forum, overview, John E. Kelly, page 15]</ref>

[[Nuclear power in Australia|Australia]] joined the forum in 2016.<ref>https://archive.is/20160907131656/https://www.gen-4.org/gif/jcms/c_71564/australia-joins-the-generation-iv-international-forum</ref>

In January 2018, it was reported that "the first installation of the pressure vessel cover of the world's first Gen IV reactor" had been completed on the [[HTR-PM]].<ref>http://www.world-nuclear-news.org/NN-First-HTR-PM-vessel-head-in-place-0401185.html</ref>

== Reactor types ==
Many reactor types were considered initially; however, the list was downsized to focus on the most promising technologies and those that could most likely meet the goals of the Gen IV initiative.<ref name="Generation IV"/> Three systems are nominally [[thermal reactor]]s and four are [[fast reactor]]s. The Very High Temperature Reactor (VHTR) is also being researched for potentially providing high quality process heat for [[thermochemical cycle|hydrogen production]]. The fast reactors offer the possibility of burning [[actinides]] to further reduce waste and of being able to "[[breeder reactor|breed more fuel]]" than they consume. These systems offer significant advances in sustainability, safety and reliability, economics, proliferation resistance (depending on perspective) and physical protection.

=== Thermal reactors ===
A [[Thermal-neutron reactor|thermal reactor]] is a [[nuclear reactor]] that uses slow or [[thermal neutrons]]. A [[neutron moderator]] is used to slow the [[neutron]]s emitted by fission to make them more likely to be captured by the fuel.

==== Very-high-temperature reactor (VHTR) ====
[[File:Very High Temperature Reactor.svg|right|thumb|Very-High-Temperature Reactor (VHTR)]]
{{Main article|Very high temperature reactor}}
{{see also|Fort St. Vrain Generating Station|High-temperature engineering test reactor|HTR-10}}
The '''very high temperature reactor''' concept uses a [[graphite]]-moderated core with a once-through [[uranium]] fuel cycle, using helium or molten salt as the [[Very high temperature reactor#Coolant|coolant]]. This reactor design envisions an outlet temperature of 1,000 °C. The reactor core can be either a prismatic-block or a [[pebble bed reactor]] design. The high temperatures enable applications such as process heat or [[hydrogen]] production via the thermochemical [[Sulfur-iodine cycle|iodine-sulfur]] process. It would also be [[Passive nuclear safety|passively safe]].

The planned construction of the first VHTR, the South African PBMR ([[pebble bed modular reactor]]), lost government funding in February, 2010.<ref>[http://www.powergenworldwide.com/index/display/articledisplay/6322207443/articles/power-engineering-international/volume-18/Issue_3/regulars/world-news/INTERNATIONAL.html South Africa to stop funding Pebble Bed nuclear reactor] {{webarchive|url=https://web.archive.org/web/20100909172743/http://www.powergenworldwide.com/index/display/articledisplay/6322207443/articles/power-engineering-international/volume-18/Issue_3/regulars/world-news/INTERNATIONAL.html |date=2010-09-09 }}</ref> A pronounced increase of costs and concerns about possible unexpected technical problems had discouraged potential investors and customers.

The [[Peoples Republic of China]] began construction of a 200-MW High Temperature Pebble bed reactor in 2012 as a successor to its [[HTR-10]].<ref>[http://www.nucnet.org/all-the-news/2013/01/07/china-begins-construction-of-first-generation-iv-htr-pm-unit Nucnet Report: 'China Begins Construction of First Generation IV HTR-PM Unit', 7 January 2013]</ref>

Also in 2012, as part of the [[Next Generation Nuclear Plant]] competition, [[Idaho National Laboratory]] approved a design similar to [[Areva]]'s prismatic block [http://us.areva.com/EN/home-3225/areva-inc-areva-htgr.html Antares reactor] as the chosen [[HTGR]] to be deployed as a prototype by 2021. It was in competition with [[General Atomics]]' [[Gas turbine modular helium reactor]] and [[Westinghouse Electric Company|Westinghouse]]'s [[Pebble Bed Modular Reactor]].<ref name="World nuclear news">{{cite web|url=http://www.world-nuclear-news.org/NN-Areva_modular_reactor_selected_for_NGNP_development-1502124.html|title=INL approves Antares design}}</ref>

[[X-energy]] was awarded a five-year $53M U.S. Department of Energy Advanced Reactor Concept Cooperative Agreement award to advance elements of their reactor development.<ref>[https://www.x-energy.com/doe-partnership]</ref>
The [[X-energy#Reactor Design|Xe-100]] is a pebble-bed modular reactor and will generate 200-MWt and approximately 76-MWe. The standard Xe-100 "four-pack" plant generates approximately 300-MWe and will fit on as few as 13 acres. All of the components for the Xe-100 will be road-transportable, and will be installed, rather than constructed, at the project site to streamline construction.<ref name="X-energy">{{cite web|url=https://www.x-energy.com/}}</ref>

==== Molten-salt reactor (MSR) ====
[[File:Molten Salt Reactor.svg|right|thumb|Molten Salt Reactor (MSR)]]
{{Main article|Molten salt reactor}}
{{see also|Liquid fluoride thorium reactor}}
A '''molten salt reactor'''<ref name="Roadmap"/> is a type of [[nuclear reactor]] where the primary [[coolant]], or even the fuel itself is a molten salt mixture. There have been many designs put forward for this type of reactor and a few prototypes built. The early concepts and many current ones rely on [[nuclear fuel]], perhaps [[uranium tetrafluoride]] (UF4) or [[thorium tetrafluoride]] (ThF4), dissolved in molten [[fluoride]] salt. The fluid would reach [[Nuclear reactor physics#Criticality|criticality]] by flowing into a core where [[graphite]] would serve as the [[neutron moderator|moderator]]. Many current concepts rely on fuel that is dispersed in a graphite matrix with the molten salt providing low pressure, high temperature cooling.

The Gen IV MSR is more accurately termed an [[epithermal neutron|epithermal reactor]] than a thermal reactor due to the average speed of the neutrons that would cause the fission events within its fuel being faster than [[thermal neutron]]s.<ref>{{cite web |url=https://inlportal.inl.gov/portal/server.pt?open=514&objID=1361&parentname=CommunityPage&parentid=10&mode=2&in_hi_userid=200&cached=true |title=Idaho National Laboratory detailing some current efforts at developing Gen. IV reactors}}</ref>

The principle of a MSR can be used for thermal, epithermal and fast reactors. Since 2005 the focus has moved towards a fast spectrum MSR (MSFR).<ref>H. Boussier, S. Delpech, V. Ghetta et Al. : The Molten Salt Reactor (MSR) in Generation IV: Overview and Perspectives, GIF SYMPOSIUM PROCEEDINGS/2012 ANNUAL REPORT, NEA No. 7141, pp95 [https://www.gen-4.org/gif/jcms/c_44720/annual-reports]
</ref>

While most MSR designs being pursued are largely derived from the 1960s [[Molten-Salt Reactor Experiment]](MSRE), variants of molten salt technology include the conceptual ''[[Dual fluid reactor]]'' which is being designed with lead as a cooling medium but molten salt fuel, commonly as the metal chloride e.g. [[Plutonium(III) chloride]], to aid in greater "nuclear waste" closed-fuel cycle capabilities.
Other notable approaches differing substantially from MSRE include the ''[[Stable Salt Reactor]]''(SSR) concept promoted by MOLTEX, which encases the molten salt in hundreds of the common solid [[fuel rod]]s that are already well established in the nuclear industry. This latter British design was found to be the most competitive for [[Small modular reactor]] development by a British-based consultancy firm ''Energy Process Development'' in 2015.<ref>[http://www.daretothink.org/europe-moltex-stable-salt-reactor/ Europe: Moltex’ Stable Salt Reactor]</ref><ref>[http://analysis.nuclearenergyinsider.com/moltex-energy-sees-uk-canada-smr-licensing-springboard-asia Moltex Energy sees UK, Canada SMR licensing as springboard to Asia Jun 28, 2016]</ref>

Another notable feature of the MSR is the possibility of a [[Thermal-neutron reactor|thermal spectrum]] nuclear [[Nuclear fuel cycle#Fuel cycles|waste-burner]]. Conventionally only fast spectrum reactors have been considered viable for [[Nuclear fuel cycle#Minor actinides recycling|utilization or reduction]] of the [[Spent nuclear fuel|spent nuclear stockpiles]]. The conceptual viability of a thermal waste-burner was first shown in a whitepaper by [[Seaborg Technologies]] spring 2015.<ref name="Seaborg Whitepaper 2015">{{cite web|url=https://seaborg.dk/s/Seaborg-whitepaper-2015.pdf|title=Thermal MSR waste burner benchmark}}</ref> Thermal waste-burning was achieved by replacing a fraction of the [[uranium]] in the spent nuclear fuel with [[thorium]]. The net production rate of [[transuranium element]] (e.g. [[plutonium]] and [[americium]]) is reduced below the consumption rate, thus reducing the magnitude of the [[Radioactive waste|nuclear storage problem]]. Without the [[nuclear proliferation]] concerns and other [[Fast-neutron reactor#Disadvantages|technical issues]] associated with a [[Fast-neutron reactor|fast reactor]].

==== Supercritical-water-cooled reactor (SCWR) ====
[[File:Supercritical-Water-Cooled Reactor.svg|right|thumb|Supercritical-Water-Cooled Reactor (SCWR)]]
{{Main article|Supercritical water reactor}}
The '''supercritical water reactor''' (SCWR)<ref name="Roadmap"/> is a [[reduced moderation water reactor]] concept that, due to the average speed of the neutrons that would cause the fission events within the fuel being faster than [[thermal neutron]]s, it is more accurately termed an [[epithermal neutron|epithermal reactor]] than a thermal reactor. It uses [[supercritical fluid|supercritical water]] as the working fluid. SCWRs are basically [[light water reactor]]s (LWR) operating at higher pressure and temperatures with a direct, once-through heat exchange cycle. As most commonly envisioned, it would operate on a direct cycle, much like a boiling water reactor ([[BWR]]), but since it uses supercritical water (not to be confused with [[Critical mass (nuclear)|critical mass]]) as the working fluid, it would have only one water phase present, which makes the supercritical heat exchange method more similar to a pressurized water reactor ([[Pressurized water reactor|PWR]]). It could operate at much higher temperatures than both current PWRs and BWRs.

Supercritical water-cooled reactors (SCWRs) are promising advanced nuclear systems because of their high [[thermal efficiency]] (i.e., about 45% vs. about 33% efficiency for current LWRs) and considerable plant simplification.

The main mission of the SCWR is generation of low-cost [[electricity]]. It is built upon two proven technologies, LWRs, which are the most commonly deployed power generating reactors in the world, and superheated [[fossil fuel]] fired [[boiler]]s, a large number of which are also in use around the world. The SCWR concept is being investigated by 32 organizations in 13 countries.{{citation needed|date=October 2012}}

Because SCWRs are water reactors they share the steam explosion and radioactive steam release hazards of BWRs and LWRs as well as the need for extremely expensive heavy duty pressure vessels, pipes, valves, and pumps. These shared problems are inherently more severe for SCWRs due to operation at higher temperatures.

A SCWR Design under development is the [[VVER]]-1700/393 (VVER-SCWR or VVER-SKD) — a Russian Supercritical-water-cooled reactor with double-inlet-core and a [[breeder reactor|breeding ratio]] of 0.95.<ref name="powertecrussia.com">{{cite web |url=http://www.powertecrussia.com/blog/tag/nuclear-power/ |title=Technology Developments & Plant Efficiency for the Russian Nuclear Power Generation Market Wednesday |date=March 24, 2010}}</ref>

=== Fast reactors ===
A [[Fast-neutron reactor|fast reactor]] directly uses the fast neutrons emitted by fission, without moderation. Unlike thermal neutron reactors, fast neutron reactors can be configured to "'''burn'''", or fission, all [[actinides]], and given enough time, therefore drastically reduce the actinides fraction in [[spent nuclear fuel]] produced by the present world fleet of thermal neutron [[light water reactor]]s, thus closing the [[nuclear fuel cycle]]. Alternatively, if configured differently, they can also [[breeder reactor|'''breed''']] more actinide fuel than they consume.

==== Gas-cooled fast reactor (GFR) ====
[[File:Gas-Cooled Fast Reactor Schemata.svg|right|thumb|Gas-Cooled Fast Reactor (GFR)]]
{{Main article|Gas-cooled fast reactor}}
The '''gas-cooled fast reactor''' (GFR)<ref name="Roadmap"/> system features a fast-neutron spectrum and closed fuel cycle for efficient conversion of [[Fertile material|fertile uranium]] and management of actinides. The reactor is [[helium]]-cooled and with an outlet temperature of 850 °C it is an evolution of the [[very-high-temperature reactor]] (VHTR) to a more sustainable fuel cycle. It will use a direct [[Brayton cycle]] [[Closed-cycle gas turbine|gas turbine]] for high thermal efficiency. Several fuel forms are being considered for their potential to operate at very high temperatures and to ensure an excellent retention of [[Nuclear fission|fission]] products: composite [[ceramic]] fuel, advanced fuel particles, or ceramic clad elements of actinide compounds. Core configurations are being considered based on pin- or plate-based fuel assemblies or prismatic blocks.

The European Sustainable Nuclear Industrial Initiative is funding three Generation IV reactor systems, one of which is a gas-cooled fast reactor, called ''Allegro'', 100 MW(t), which will be built in a central or eastern European country with construction expected to begin in 2018.<ref name="euronuclear.org">{{cite web|url=https://www.euronuclear.org/1-information/news/Gen-IV.htm |title=The European Sustainable Nuclear Industrial Initiative (ESNII) will support three Generation IV reactor systems: a sodium-cooled fast reactor, or SFR, called ''Astrid'' that is proposed by France; a gas-cooled fast reactor, GFR, called ''Allegro'' supported by central and eastern Europe; and a lead-cooled fast reactor, LFR, technology pilot called ''Myrrha'' that is proposed by Belgium. |deadurl=yes |archiveurl=https://web.archive.org/web/20131009042600/http://euronuclear.org/1-information/news/Gen-IV.htm |archivedate=2013-10-09 |df= }}</ref> The central European [[Visegrád Group]] are committed to pursuing the technology.<ref>{{cite web |url=http://www.alphagalileo.org/ViewItem.aspx?ItemId=133111&CultureCode=en |title=The V4G4 Centre of Excellence for performing joint research, development and innovation in the field of Generation-4 (G4) nuclear reactors have been established. 20 July 2013 National Center for Nuclear Research (NCBJ)}}</ref> In 2013 German, British, and French institutes finished a 3-year collaboration study on the follow on industrial scale design, known as ''GoFastR''.<ref>{{cite web|url=http://www.ist-world.org/ProjectDetails.aspx?ProjectId=5cb8f3f283574cc6b2bdbf72533172d8 |title=the European Gas cooled Fast Reactor. |deadurl=yes |archiveurl=https://web.archive.org/web/20131213091046/http://www.ist-world.org/ProjectDetails.aspx?ProjectId=5cb8f3f283574cc6b2bdbf72533172d8 |archivedate=2013-12-13 |df= }}</ref> They were funded by the EU's 7th FWP [[framework programme]], with the goal of making a sustainable VHTR.<ref>{{cite web |url=http://www.2020-horizon.com/GOFASTR-European-Gas-Cooled-Fast-Reactor%28GOFASTR%29-s312.html |title=The GOFASTR research program}}</ref>

==== Sodium-cooled fast reactor (SFR) ====
[[File:Sodium-Cooled Fast Reactor Schemata.svg|right|thumb|Pool design Sodium-Cooled Fast Reactor (SFR)]]
{{Main article|Sodium-cooled fast reactor}}
{{see also|Prototype Fast Breeder Reactor|Experimental Breeder Reactor II|S-PRISM|BN-800 reactor|Toshiba 4S|CFR-600}}

In India, the [[Fast Breeder Test Reactor]] reached criticality in October 1985. In September 2002, fuel burn-up in the FBTR for the first time reached the 100,000 megawatt-days per metric ton uranium (MWd/MTU) mark. This is considered an important milestone in breeder reactor technology. Using the experience gained from the operation of the FBTR, the [[Prototype Fast Breeder Reactor]], a 500 MWe Sodium cooled fast reactor is being built at a cost of INR 5,677 crores (~US$900 million) and is expected to be critical by June 2018. The PFBR will be followed by six more Commercial Fast Breeder Reactors (CFBRs) of 600 MWe each.

The SFR<ref name="Roadmap"/> is a project that builds on two closely related existing projects, the liquid metal [[Breeder reactor#Fast breeder reactor|fast breeder reactor]] and the [[integral fast reactor]].

The goals are to increase the efficiency of uranium usage by [[breeder reactor|breeding]] plutonium and eliminating the need for [[transuranic]] isotopes ever to leave the site. The reactor design uses an unmoderated core running on [[fast neutron]]s, designed to allow any transuranic isotope to be consumed (and in some cases used as fuel). In addition to the benefits of removing the long [[half-life]] transuranics from the waste cycle, the SFR fuel expands when the reactor overheats, and the chain reaction automatically slows down. In this manner, it is passively safe.<ref>{{cite web |url=http://www.ne.anl.gov/About/hn/logos-winter02-psr.shtml|title=Passively safe reactors rely on nature to keep them cool|author=David Baurac}}</ref>

The SFR reactor concept is cooled by liquid [[sodium]] and fueled by a metallic alloy of uranium and [[plutonium]] or [[spent nuclear fuel]], the "nuclear waste" of [[light water reactor]]s. The SFR fuel is contained in steel cladding with liquid sodium filling in the space between the clad elements which make up the fuel assembly. One of the design challenges of an SFR is the risks of handling sodium, which reacts explosively if it comes into contact with water. However, the use of liquid metal instead of water as coolant allows the system to work at atmospheric pressure, reducing the risk of leakage.

The European Sustainable Nuclear Industrial Initiative is funding three Generation IV reactor systems, one of which is a sodium-cooled fast reactor, called ''[[ASTRID (reactor)|ASTRID]]'', Advanced Sodium Technical Reactor for Industrial Demonstration, [[Areva]], [[Commissariat à l'énergie atomique et aux énergies alternatives|CEA]] and [[Électricité de France|EDF]] are leading the design with British collaboration.<ref>{{cite web |url=http://www.power-eng.com/articles/2010/11/areva--cea-secure.html |title=Areva, CEA secure EUR650m funding to develop ASTRID sodium-cooled Generation IV reactor 11/11/2010}}</ref><ref>{{cite web |url=http://www.powermag.com/uk-and-france-sign-landmark-civil-nuclear-cooperation-agreement/ |title=UK and France Sign Landmark Civil Nuclear Cooperation Agreement 02/22/2012 . POWERnews}}</ref> Astrid will be rated about 600 MWe and is proposed to be built in France, near to the [[Phénix]] reactor. A final decision in construction is to be made in 2019<ref name="euronuclear.org"/>

The [[China|PRC]]'s first commercial-scale, 800 MWe, fast neutron reactor, to be situated near [[Sanming]] in [[Fujian province]] will be a SFR. In 2009 an agreement was signed that would entail the Russian [[BN-800 reactor]] design to be sold to the PRC once it is completed, this would be the first time commercial-scale fast neutron reactors have ever been exported.<ref>{{cite web |url=http://www.world-nuclear-news.org/C-Joint_venture_launched_for_Chinese_fast_reactor-3004104.html |title=Joint venture launched for Chinese fast reactor}}</ref> The BN-800 reactor became operational in 2014.

The 400 MWe [[Fast Flux Test Facility]] operated successfully for ten years at the Hanford site in Washington State.

The 20 MWe [[EBR II]] operated successfully for over thirty years at the Idaho National Laboratory, until it was shut down in 1994.

GE Hitachi's [[PRISM (reactor)|PRISM]] reactor is an SFR with the primary purpose of reducing the half lives of the fissionable elements present in used nuclear fuel while generating electricity largely as a by-product.

==== Lead-cooled fast reactor (LFR) ====
[[File:Lead-Cooled Fast Reactor Schemata.svg|right|thumb|Lead-Cooled Fast Reactor (LFR)]]
{{Main article|Lead-cooled fast reactor}}
{{See also|MYRRHA}}
The '''lead-cooled fast reactor'''<ref name="Roadmap">{{cite journal|year=2002 |title=A Technology Roadmap for Generation IV Nuclear Energy Systems |last=US DOE Nuclear Energy Research Advisory Committee |volume=GIF-002-00 |url=http://nuclear.energy.gov/genIV/documents/gen_iv_roadmap.pdf |deadurl=yes |archiveurl=https://web.archive.org/web/20071129121214/http://nuclear.energy.gov/genIV/documents/gen_iv_roadmap.pdf |archivedate=2007-11-29 |df= }}</ref> features a fast-neutron-spectrum [[lead]] or [[lead]]/[[bismuth]] [[eutectic]] ([[Lead-bismuth eutectic|LBE]]) liquid-metal-cooled reactor with a closed [[Nuclear fuel cycle|fuel cycle]]. Options include a range of plant ratings, including a "battery" of 50 to 150 MW of electricity that features a very long refueling interval, a modular system rated at 300 to 400 MW, and a large monolithic plant option at 1,200 MW (The term ''battery'' refers to the long-life, factory-fabricated core, not to any provision for electrochemical energy conversion). The fuel is metal or nitride-based containing [[Fertile material|fertile uranium]] and [[transuranic]]s. The LFR is cooled by natural [[convection]] with a reactor outlet coolant temperature of 550 °C, possibly ranging up to 800 °C with advanced materials. The higher temperature enables the production of [[Thermochemical cycle|hydrogen by thermochemical processes]].

The European Sustainable Nuclear Industrial Initiative is funding three Generation IV reactor systems, one of which is a lead-cooled fast reactor that is also an [[Subcritical reactor|accelerator-driven sub-critical]] reactor, called ''[[MYRRHA]]'', 100 MW(t), which will be built in [[Belgium]] with construction expected to begin after 2014 and the industrial scale version, known as ''Alfred'', slated to be constructed sometime after 2017. A reduced-power model of Myrrha called ''Guinevere'' was started up at [[Mol, Belgium|Mol]] in March 2009.<ref name="euronuclear.org"/> In 2012 the research team reported that Guinevere was operational.<ref>{{cite news|last1=Hellemans|first1=Alexander|title=Reactor-Accelerator Hybrid Achieves Successful Test Run|url=http://news.sciencemag.org/physics/2012/01/reactor-accelerator-hybrid-achieves-successful-test-run|accessdate=29 December 2014|work=Science Insider|date=12 January 2012}}</ref>

Two other lead-cooled fast reactors under development are the SVBR-100, a modular 100 MWe lead-bismuth cooled fast neutron reactor concept designed by OKB [[Gidropress]] in Russia and the [[BREST (Reactor)|BREST-OD-300]] (Lead-cooled fast reactor) 300 MWe, to be developed after the SVBR-100, and built over 2016-20, it will dispense with the [[Uranium-238|fertile blanket]] around the core and will supersede the sodium cooled [[BN-600 reactor]] design, to purportedly give enhanced proliferation resistance.<ref name="powertecrussia.com"/>

== Advantages and disadvantages ==
Relative to current nuclear power plant technology, the claimed benefits for 4th generation reactors include:
* Nuclear waste that remains radioactive for a few centuries instead of millennia<ref>{{cite web |title=Strategies to Address Global Warming |url=http://www.columbia.edu/~jeh1/mailings/2009/20090713_Strategies.pdf}}</ref>
* 100–300 times more energy yield from the same amount of nuclear fuel<ref>{{cite web |title=4th Generation Nuclear Power |url=http://www.ossfoundation.us/projects/energy/nuclear}}</ref>
* Broader range of fuels, and even unencapsulated raw fuels (non-pebble [[Molten Salt Reactor|MSR]], [[Liquid fluoride thorium reactor|LFTR]]).
* In some reactors, the ability to consume existing nuclear waste in the production of electricity, that is, a Closed [[nuclear fuel cycle]]. This strengthens the argument to deem [[nuclear power as renewable energy]].
* Improved operating safety features, such as (depending on design) avoidance of pressurized operation, automatic passive (unpowered, uncommanded) reactor shutdown, avoidance of water cooling and the associated risks of loss of water (leaks or boiling) and hydrogen generation/explosion and contamination of coolant water.

Nuclear reactors do not emit CO2 during operation, although like all [[low carbon power]] sources, the mining and construction phase can result in CO2 emissions, if energy sources which are not carbon neutral (such as fossil fuels), or CO2 emitting cements are used during the construction process.
A 2012 [[Yale University]] review published in the Journal of Industrial Ecology analyzing {{CO2}} [[life cycle assessment]] (LCA) emissions from [[nuclear power]] determined that:<ref name="Warner + Heath, JoIE">Warner, Ethan S.; Heath, Garvin A. [http://onlinelibrary.wiley.com/doi/10.1111/j.1530-9290.2012.00472.x/full Life Cycle Greenhouse Gas Emissions of Nuclear Electricity Generation: Systematic Review and Harmonization], ''Journal of Industrial Ecology'', [[Yale University]], published online April 17, 2012, {{doi|10.1111/j.1530-9290.2012.00472.x}}</ref>
{{Quote|The collective LCA literature indicates that life cycle [[Greenhouse gas|GHG]] [greenhouse gas] emissions from nuclear power are only a fraction of traditional fossil sources and comparable to renewable technologies.}}
Although the paper primarily dealt with data from [[Generation II reactor]]s, and did not analyze the {{CO2}} emissions by 2050 of the presently under construction [[Generation III reactor]]s, it did summarize the Life Cycle Assessment findings of in development reactor technologies.{{Quote|FBRs ['[[Fast Breeder Reactor]]s'] have been evaluated in the LCA literature. The limited literature that evaluates this potential future technology reports [[median]] life cycle GHG emissions... similar to or lower than LWRs [Gen II [[light water reactor]]s] and purports to consume little or no [[uranium market|uranium ore]].}}

A specific risk of the sodium-cooled fast reactor is related to using metallic sodium as a coolant. In case of a breach, sodium explosively reacts with water. Fixing breaches may also prove dangerous, as the cheapest noble gas [[argon]] is also used to prevent sodium oxidation. Argon, like helium, can displace oxygen in the air and can pose [[hypoxia (environmental)|hypoxia]] concerns, so workers may be exposed to this additional risk. This is a pertinent problem as demonstrated by the events at the [[LMFBR|loop type]] [[Monju Nuclear Power Plant|Prototype Fast Breeder Reactor Monju]] at Tsuruga, Japan.<ref>{{cite news |title=Japan Strains to Fix a Reactor Damaged Before Quake |url=https://www.nytimes.com/2011/06/18/world/asia/18japan.html | work=The New York Times | first=Hiroko |last=Tabuchi |date=17 June 2011}}</ref>
Using lead or molten salts mitigates this problem by making the coolant less reactive and allowing a high freezing temperature and low pressure in case of a leak. Disadvantages of lead compared to sodium are much higher viscosity, much higher density, lower heat capacity, and more radioactive neutron activation products.

In many cases, there is already a large amount of experience built up with numerous proof of concept Gen IV designs. For example, the reactors at [[Fort St. Vrain Generating Station]] and [[HTR-10]] are similar to the proposed Gen IV [[VHTR]] designs, and the [[LMFBR|pool type]] [[EBR-II]], [[Phénix]] and [[BN-600]] reactor are similar to the proposed pool type Gen IV Sodium Cooled Fast reactors being designed.

== Table of designs ==

{| class=wikitable
|+ Summary of designs for generation IV reactors<ref>https://www.gen-4.org/gif/upload/docs/application/pdf/2013-09/gif_rd_outlook_for_generation_iv_nuclear_energy_systems.pdf</ref>
|-
! System
! Neutron Spectrum
! Coolant
! Temperature (°C)
! Fuel Cycle
! Size (MW)
!Example developers
|-
| [[Very-high-temperature reactor|VHTR]]
| Thermal
| Helium
| 900–1000
| Open
| 250–300
|[[Japan Atomic Energy Agency|JAEA]] ([[High-temperature engineering test reactor|HTTR]]), [[Tsinghua University]] ([[HTR-10]]), [[X-energy]]<ref name="energy.gov">{{cite web|title=Energy Department Announces New Investments in Advanced Nuclear Power Reactors...|url=https://www.energy.gov/articles/energy-department-announces-new-investments-advanced-nuclear-power-reactors-help-meet|website=[[United States Department of Energy|US Department of Energy]]|accessdate=16 January 2016}}</ref>
|-
| [[Sodium-cooled fast reactor|SFR]]
| Fast
| Sodium
| 550
| Closed
| 30–150, 300–1500, 1000–2000
|[[TerraPower]] ([[Traveling wave reactor|TWR]]), [[Toshiba]] ([[Toshiba 4S|4S]]), [[GE Hitachi Nuclear Energy]] ([[PRISM (reactor)|PRISM]])
|-
| [[Supercritical water reactor|SCWR]]
| Thermal or fast
| Water
| 510–625
| Open or closed
| 300–700, 1000–1500
|
|-
| [[Gas-cooled fast reactor|GFR]]
| Fast
| Helium
| 850
| Closed
| 1200
|[[Energy Multiplier Module]]
|-
| [[Lead-cooled fast reactor|LFR]]
| Fast
| Lead
| 480–800
| Closed
| 20–180, 300–1200, 600–1000
|
|-
| [[Molten salt reactor|MSR]]
| Fast or thermal
| Fluoride or chloride salts
| 700–800
| Closed
| 250, 1000
|[[Seaborg Technologies]], [[TerraPower]], [[Stable Salt Reactor|Moltex Energy]], [[Flibe Energy]] ([[Liquid fluoride thorium reactor|LFTR]]), [[Transatomic Power]], Thorium Tech Solution ([[Fuji Molten Salt Reactor|FUJI MSR]]), Terrestrial Energy ([[IMSR]]), [[Southern Company Services|Southern Company]]<ref name="energy.gov"/>, [[Elysium Industries]]<ref>http://www.elysiumindustries.com/</ref>
|-
| [[Dual fluid reactor|DFR]]
| Fast
| Lead
| 1000
| Closed
| 500–1500
| Institute for Solid-State Nuclear Physics<ref name=ifk>{{cite web |url=https://festkoerper-kernphysik.de/dfr.pdf |title=Dual Fluid Reactor - IFK |date=2013-06-16 |website=festkoerper-kernphysik.de |publisher= Institut für Festkörper-Kernphysik |format=PDF |location=Berlin, Germany |access-date=2017-08-28}}</ref>, [[Aristos Power]] <ref name=HSR>{{|url=http://aristospower.tk |title=Hard Spectrum Reactor - HSR</ref>
|}

== See also ==
{{portal|Energy|Nuclear technology}}
{{colbegin}}
* [[Nuclear reactor]]
* [[Nuclear material]]
* [[Nuclear physics]]
* [[List of reactor types#Reactor types|List of reactor types]]
* [[Generation II reactor]]
* [[Generation III reactor]]
* [[Integral Fast Reactor]]
* [[Liquid fluoride thorium reactor]]
* [[Breeder reactor]]
* [[Small modular reactor]]
{{colend}}

==References==
{{Reflist|30em}}

== External links ==
* [https://inlportal.inl.gov/portal/server.pt?open=514&objID=1361&parentname=CommunityPage&parentid=10&mode=2&in_hi_userid=200&cached=true Article from Idaho National Laboratory detailing some current efforts at developing Gen. IV reactors.]
* [http://www.gen-4.org/ Generation IV International Forum (GIF)]
* [https://web.archive.org/web/20070205115654/http://nuclear.energy.gov/genIV/neGenIV1.html U.S. Department of Energy Office of Nuclear Energy, Science and Technology]
* [https://web.archive.org/web/20060512033030/http://www.engr.utk.edu/nuclear/colloquia/slides/Gen%20IV%20U-Tenn%20Presentation.pdf Gen IV presentation]
* [http://www.ecology.at/ecology/files/pr577_1.pdf Science or Fiction - Is there a Future for Nuclear?] (Nov. 2007) - A publication from the Austrian [[Ecology Institute (Austria)|Ecology Institute]] about 'Generation IV' and Fusion reactors.
* {{cite web |url=http://memagazine.asme.org/Articles/2011/December/Nuclear_Power_After_Fukushima.cfm |title=Nuclear Power After Fukushima |author=Gail H. Marcus |date=December 2011 |work=Mechanical Engineering (the magazine of [[ASME]]) |accessdate=23 January 2012}} "In the wake of a severe plant accident, advanced reactor designs are getting renewed attention."
* [http://www.itheo.org/ International Thorium Energy Organisation - www.IThEO.org]
* [http://www.ithec.org/ International Thorium Energy Committee - iThEC]

{{Nuclear fission reactors}}

[[Category:Nuclear power reactor types]]
[[Category:Idaho National Laboratory]]

Benutzer:Snackroeg/Kernreaktoren der Generation 5

2018-02-25T05:46:50Z

Boundarylayer:

{{update|date=October 2017}}
[[File:GenIVRoadmap-en.svg|thumb|480px|Nuclear Energy Systems Deployable no later than 2030 and offering significant advances in sustainability, safety and reliability, and economics]]

'''Generation IV reactors''' ('''Gen IV''') are a set of [[nuclear reactor]] designs currently being researched for commercial applications by the Generation IV International Forum, with [[Technology readiness level]]s varying between the level requiring a demonstration, to economical competitive implementation.<ref>{{Cite journal|last=Locatelli|first=Giorgio|last2=Mancini|first2=Mauro|last3=Todeschini|first3=Nicola|date=2013-10-01|title=Generation IV nuclear reactors: Current status and future prospects|url=http://www.sciencedirect.com/science/article/pii/S0301421513006083|journal=Energy Policy|volume=61|pages=1503–1520|doi=10.1016/j.enpol.2013.06.101}}</ref> They are motivated by a variety of goals including improved safety, sustainability, efficiency, and cost.

The most developed Gen IV reactor design, the [[sodium fast reactor]], has received the greatest share of funding over the years, with the principle Gen IV aspect of the design, relating in largest part to the development of a sustainable [[nuclear fuel cycle|closed fuel cycle]] for the reactor. Amongst nuclear engineers the [[molten-salt reactor]], the least developed and funded technology, is the safest of the six models.<ref>[https://www.scientificamerican.com/article/can-sodium-save-nuclear-power/ Can Sodium Save Nuclear Power? Scientific American]</ref><ref>{{cite journal |last1=Moir |first1=Ralph |last2=Teller |first2=Edward |year=2005 |title=Thorium-Fueled Underground Power Plant Based on Molten Salt Technology |journal=Nuclear Technology |volume=151 |issue=3 |pages=334–340 |publisher=[[American Nuclear Society]] |url=http://www.new.ans.org/pubs/journals/nt/a_3655 |accessdate=March 22, 2012 }}</ref>

The majority of the 6 designs are generally not expected to be available for commercial construction until 2020–30.<ref name="Generation IV">[http://www.world-nuclear.org/info/Nuclear-Fuel-Cycle/Power-Reactors/Generation-IV-Nuclear-Reactors/]</ref> Presently the majority of reactors in operation around the world are considered [[Generation II reactor|second generation reactor]] systems, as the vast majority of the [[Nuclear reactor#Classification by generation|first generation]] systems were retired some time ago, and there are only a dozen or so [[Generation III reactor]]s in operation as of 2014.
[[Nuclear reactor#Generation V+ reactors|Generation V reactors]] refer to reactors that are purely theoretical and are therefore not yet considered feasible in the short term, resulting in limited [[R&D]] funding.

== History ==
The Generation IV International Forum (GIF) is "a co-operative international endeavour which was set up to carry out the research and development needed to establish the feasibility and performance capabilities of the next generation nuclear energy systems."<ref>{{Cite web|url=https://www.gen-4.org/gif/jcms/c_9260/public|title=GIF Portal - Home - Public|website=www.gen-4.org|access-date=2016-07-25}}</ref> It was founded in 2001. Currently active members of the Generation IV International Forum (GIF) include: [[Australia]], [[Canada]], [[China]], the [[European Atomic Energy Community]] (Euratom), [[France]], [[Japan]], [[Russia]], [[South Africa]], [[South Korea]], [[Switzerland]], and the [[United States]]. The non-active members are [[Argentina]], [[Brazil]], and the [[United Kingdom]].<ref name="gen-4">{{cite web|url=https://www.gen-4.org/gif/jcms/c_9492/members|title=GIF Membership|website=gen-4.org|accessdate=28 October 2014}}</ref> Switzerland joined in 2002, Euratom in 2003, and China and Russia in 2006. The remaining countries (excluding Australia) were founding members.<ref name="gen-4" />

The 36th GIF meeting in [[Brussels]] was held in November 2013.<ref>{{cite web|url=https://www.energy.gov/ne/articles/generation-iv-international-forum-updates-technology-roadmap-and-builds-future|title=generation IV international forum updates technology roadmap and builds future. DOE}}</ref><ref>{{cite web|url=http://events.r20.constantcontact.com/register/event?llr=mscrkjkab&oeidk=a07e7melf609716b2c6 |title=The Generation IV international forum holds their 36th meeting on Monday 18th Nov 2013 in Brussels. }}{{dead link|date=January 2017 |bot=InternetArchiveBot |fix-attempted=yes }}</ref> The ''Technology Roadmap Update for Generation IV Nuclear Energy Systems'' was published in January 2014 which details R&D objectives for the next decade.<ref>[https://web.archive.org/web/20140625102915/https://www.gen-4.org/gif/upload/docs/application/pdf/2014-03/gif-tru2014.pdf Technology Roadmap Update for Generation IV Nuclear Energy Systems]</ref> A breakdown of the reactor designs being researched by each forum member has been made available.<ref>[https://web.archive.org/web/20140708023538/https://www.gen-4.org/gif/upload/docs/application/pdf/2014-03/gif_overview_presentation_v9_final3_web.pdf Generation IV International Forum, overview, John E. Kelly, page 15]</ref>

[[Nuclear power in Australia|Australia]] joined the forum in 2016.<ref>https://archive.is/20160907131656/https://www.gen-4.org/gif/jcms/c_71564/australia-joins-the-generation-iv-international-forum</ref>

In January 2018, it was reported that "the first installation of the pressure vessel cover of the world's first Gen IV reactor" had been completed on the [[HTR-PM]].<ref>http://www.world-nuclear-news.org/NN-First-HTR-PM-vessel-head-in-place-0401185.html</ref>

== Reactor types ==
Many reactor types were considered initially; however, the list was downsized to focus on the most promising technologies and those that could most likely meet the goals of the Gen IV initiative.<ref name="Generation IV"/> Three systems are nominally [[thermal reactor]]s and four are [[fast reactor]]s. The Very High Temperature Reactor (VHTR) is also being researched for potentially providing high quality process heat for [[thermochemical cycle|hydrogen production]]. The fast reactors offer the possibility of burning [[actinides]] to further reduce waste and of being able to "[[breeder reactor|breed more fuel]]" than they consume. These systems offer significant advances in sustainability, safety and reliability, economics, proliferation resistance (depending on perspective) and physical protection.

=== Thermal reactors ===
A [[Thermal-neutron reactor|thermal reactor]] is a [[nuclear reactor]] that uses slow or [[thermal neutrons]]. A [[neutron moderator]] is used to slow the [[neutron]]s emitted by fission to make them more likely to be captured by the fuel.

==== Very-high-temperature reactor (VHTR) ====
[[File:Very High Temperature Reactor.svg|right|thumb|Very-High-Temperature Reactor (VHTR)]]
{{Main article|Very high temperature reactor}}
{{see also|Fort St. Vrain Generating Station|High-temperature engineering test reactor|HTR-10}}
The '''very high temperature reactor''' concept uses a [[graphite]]-moderated core with a once-through [[uranium]] fuel cycle, using helium or molten salt as the [[Very high temperature reactor#Coolant|coolant]]. This reactor design envisions an outlet temperature of 1,000 °C. The reactor core can be either a prismatic-block or a [[pebble bed reactor]] design. The high temperatures enable applications such as process heat or [[hydrogen]] production via the thermochemical [[Sulfur-iodine cycle|iodine-sulfur]] process. It would also be [[Passive nuclear safety|passively safe]].

The planned construction of the first VHTR, the South African PBMR ([[pebble bed modular reactor]]), lost government funding in February, 2010.<ref>[http://www.powergenworldwide.com/index/display/articledisplay/6322207443/articles/power-engineering-international/volume-18/Issue_3/regulars/world-news/INTERNATIONAL.html South Africa to stop funding Pebble Bed nuclear reactor] {{webarchive|url=https://web.archive.org/web/20100909172743/http://www.powergenworldwide.com/index/display/articledisplay/6322207443/articles/power-engineering-international/volume-18/Issue_3/regulars/world-news/INTERNATIONAL.html |date=2010-09-09 }}</ref> A pronounced increase of costs and concerns about possible unexpected technical problems had discouraged potential investors and customers.

The [[Peoples Republic of China]] began construction of a 200-MW High Temperature Pebble bed reactor in 2012 as a successor to its [[HTR-10]].<ref>[http://www.nucnet.org/all-the-news/2013/01/07/china-begins-construction-of-first-generation-iv-htr-pm-unit Nucnet Report: 'China Begins Construction of First Generation IV HTR-PM Unit', 7 January 2013]</ref>

Also in 2012, as part of the [[Next Generation Nuclear Plant]] competition, [[Idaho National Laboratory]] approved a design similar to [[Areva]]'s prismatic block [http://us.areva.com/EN/home-3225/areva-inc-areva-htgr.html Antares reactor] as the chosen [[HTGR]] to be deployed as a prototype by 2021. It was in competition with [[General Atomics]]' [[Gas turbine modular helium reactor]] and [[Westinghouse Electric Company|Westinghouse]]'s [[Pebble Bed Modular Reactor]].<ref name="World nuclear news">{{cite web|url=http://www.world-nuclear-news.org/NN-Areva_modular_reactor_selected_for_NGNP_development-1502124.html|title=INL approves Antares design}}</ref>

[[X-energy]] was awarded a five-year $53M U.S. Department of Energy Advanced Reactor Concept Cooperative Agreement award to advance elements of their reactor development.<ref>[https://www.x-energy.com/doe-partnership]</ref>
The [[X-energy#Reactor Design|Xe-100]] is a pebble-bed modular reactor and will generate 200-MWt and approximately 76-MWe. The standard Xe-100 "four-pack" plant generates approximately 300-MWe and will fit on as few as 13 acres. All of the components for the Xe-100 will be road-transportable, and will be installed, rather than constructed, at the project site to streamline construction.<ref name="X-energy">{{cite web|url=https://www.x-energy.com/}}</ref>

==== Molten-salt reactor (MSR) ====
[[File:Molten Salt Reactor.svg|right|thumb|Molten Salt Reactor (MSR)]]
{{Main article|Molten salt reactor}}
{{see also|Liquid fluoride thorium reactor}}
A '''molten salt reactor'''<ref name="Roadmap"/> is a type of [[nuclear reactor]] where the primary [[coolant]], or even the fuel itself is a molten salt mixture. There have been many designs put forward for this type of reactor and a few prototypes built. The early concepts and many current ones rely on [[nuclear fuel]], perhaps [[uranium tetrafluoride]] (UF4) or [[thorium tetrafluoride]] (ThF4), dissolved in molten [[fluoride]] salt. The fluid would reach [[Nuclear reactor physics#Criticality|criticality]] by flowing into a core where [[graphite]] would serve as the [[neutron moderator|moderator]]. Many current concepts rely on fuel that is dispersed in a graphite matrix with the molten salt providing low pressure, high temperature cooling.

The Gen IV MSR is more accurately termed an [[epithermal neutron|epithermal reactor]] than a thermal reactor due to the average speed of the neutrons that would cause the fission events within its fuel being faster than [[thermal neutron]]s.<ref>{{cite web |url=https://inlportal.inl.gov/portal/server.pt?open=514&objID=1361&parentname=CommunityPage&parentid=10&mode=2&in_hi_userid=200&cached=true |title=Idaho National Laboratory detailing some current efforts at developing Gen. IV reactors}}</ref>

The principle of a MSR can be used for thermal, epithermal and fast reactors. Since 2005 the focus has moved towards a fast spectrum MSR (MSFR).<ref>H. Boussier, S. Delpech, V. Ghetta et Al. : The Molten Salt Reactor (MSR) in Generation IV: Overview and Perspectives, GIF SYMPOSIUM PROCEEDINGS/2012 ANNUAL REPORT, NEA No. 7141, pp95 [https://www.gen-4.org/gif/jcms/c_44720/annual-reports]
</ref>

While most MSR designs being pursued are largely derived from the 1960s [[Molten-Salt Reactor Experiment]](MSRE), variants of molten salt technology include the conceptual ''[[Dual fluid reactor]]'' which is being designed with lead as a cooling medium but molten salt fuel, commonly as the metal chloride e.g. [[Plutonium(III) chloride]], to aid in greater "nuclear waste" closed-fuel cycle capabilities.
Other notable approaches differing substantially from MSRE include the ''[[Stable Salt Reactor]]''(SSR) concept promoted by MOLTEX, which encases the molten salt in hundreds of the common solid [[fuel rod]]s that are already well established in the nuclear industry. This latter British design was found to be the most competitive for [[Small modular reactor]] development by a British-based consultancy firm ''Energy Process Development'' in 2015.<ref>[http://www.daretothink.org/europe-moltex-stable-salt-reactor/ Europe: Moltex’ Stable Salt Reactor]</ref><ref>[http://analysis.nuclearenergyinsider.com/moltex-energy-sees-uk-canada-smr-licensing-springboard-asia Moltex Energy sees UK, Canada SMR licensing as springboard to Asia Jun 28, 2016]</ref>

Another notable feature of the MSR is the possibility of a [[Thermal-neutron reactor|thermal spectrum]] nuclear [[Nuclear fuel cycle#Fuel cycles|waste-burner]]. Conventionally only fast spectrum reactors have been considered viable for [[Nuclear fuel cycle#Minor actinides recycling|utilization or reduction]] of the [[Spent nuclear fuel|spent nuclear stockpiles]]. The conceptual viability of a thermal waste-burner was first shown in a whitepaper by [[Seaborg Technologies]] spring 2015.<ref name="Seaborg Whitepaper 2015">{{cite web|url=https://seaborg.dk/s/Seaborg-whitepaper-2015.pdf|title=Thermal MSR waste burner benchmark}}</ref> Thermal waste-burning was achieved by replacing a fraction of the [[uranium]] in the spent nuclear fuel with [[thorium]]. The net production rate of [[transuranium element]] (e.g. [[plutonium]] and [[americium]]) is reduced below the consumption rate, thus reducing the magnitude of the [[Radioactive waste|nuclear storage problem]]. Without the [[nuclear proliferation]] concerns and other [[Fast-neutron reactor#Disadvantages|technical issues]] associated with a [[Fast-neutron reactor|fast reactor]].

==== Supercritical-water-cooled reactor (SCWR) ====
[[File:Supercritical-Water-Cooled Reactor.svg|right|thumb|Supercritical-Water-Cooled Reactor (SCWR)]]
{{Main article|Supercritical water reactor}}
The '''supercritical water reactor''' (SCWR)<ref name="Roadmap"/> is a [[reduced moderation water reactor]] concept that, due to the average speed of the neutrons that would cause the fission events within the fuel being faster than [[thermal neutron]]s, it is more accurately termed an [[epithermal neutron|epithermal reactor]] than a thermal reactor. It uses [[supercritical fluid|supercritical water]] as the working fluid. SCWRs are basically [[light water reactor]]s (LWR) operating at higher pressure and temperatures with a direct, once-through heat exchange cycle. As most commonly envisioned, it would operate on a direct cycle, much like a boiling water reactor ([[BWR]]), but since it uses supercritical water (not to be confused with [[Critical mass (nuclear)|critical mass]]) as the working fluid, it would have only one water phase present, which makes the supercritical heat exchange method more similar to a pressurized water reactor ([[Pressurized water reactor|PWR]]). It could operate at much higher temperatures than both current PWRs and BWRs.

Supercritical water-cooled reactors (SCWRs) are promising advanced nuclear systems because of their high [[thermal efficiency]] (i.e., about 45% vs. about 33% efficiency for current LWRs) and considerable plant simplification.

The main mission of the SCWR is generation of low-cost [[electricity]]. It is built upon two proven technologies, LWRs, which are the most commonly deployed power generating reactors in the world, and superheated [[fossil fuel]] fired [[boiler]]s, a large number of which are also in use around the world. The SCWR concept is being investigated by 32 organizations in 13 countries.{{citation needed|date=October 2012}}

Because SCWRs are water reactors they share the steam explosion and radioactive steam release hazards of BWRs and LWRs as well as the need for extremely expensive heavy duty pressure vessels, pipes, valves, and pumps. These shared problems are inherently more severe for SCWRs due to operation at higher temperatures.

A SCWR Design under development is the [[VVER]]-1700/393 (VVER-SCWR or VVER-SKD) — a Russian Supercritical-water-cooled reactor with double-inlet-core and a [[breeder reactor|breeding ratio]] of 0.95.<ref name="powertecrussia.com">{{cite web |url=http://www.powertecrussia.com/blog/tag/nuclear-power/ |title=Technology Developments & Plant Efficiency for the Russian Nuclear Power Generation Market Wednesday |date=March 24, 2010}}</ref>

=== Fast reactors ===
A [[Fast-neutron reactor|fast reactor]] directly uses the fast neutrons emitted by fission, without moderation. Unlike thermal neutron reactors, fast neutron reactors can be configured to "'''burn'''", or fission, all [[actinides]], and given enough time, therefore drastically reduce the actinides fraction in [[spent nuclear fuel]] produced by the present world fleet of thermal neutron [[light water reactor]]s, thus closing the [[nuclear fuel cycle]]. Alternatively, if configured differently, they can also [[breeder reactor|'''breed''']] more actinide fuel than they consume.

==== Gas-cooled fast reactor (GFR) ====
[[File:Gas-Cooled Fast Reactor Schemata.svg|right|thumb|Gas-Cooled Fast Reactor (GFR)]]
{{Main article|Gas-cooled fast reactor}}
The '''gas-cooled fast reactor''' (GFR)<ref name="Roadmap"/> system features a fast-neutron spectrum and closed fuel cycle for efficient conversion of [[Fertile material|fertile uranium]] and management of actinides. The reactor is [[helium]]-cooled and with an outlet temperature of 850 °C it is an evolution of the [[very-high-temperature reactor]] (VHTR) to a more sustainable fuel cycle. It will use a direct [[Brayton cycle]] [[Closed-cycle gas turbine|gas turbine]] for high thermal efficiency. Several fuel forms are being considered for their potential to operate at very high temperatures and to ensure an excellent retention of [[Nuclear fission|fission]] products: composite [[ceramic]] fuel, advanced fuel particles, or ceramic clad elements of actinide compounds. Core configurations are being considered based on pin- or plate-based fuel assemblies or prismatic blocks.

The European Sustainable Nuclear Industrial Initiative is funding three Generation IV reactor systems, one of which is a gas-cooled fast reactor, called ''Allegro'', 100 MW(t), which will be built in a central or eastern European country with construction expected to begin in 2018.<ref name="euronuclear.org">{{cite web|url=https://www.euronuclear.org/1-information/news/Gen-IV.htm |title=The European Sustainable Nuclear Industrial Initiative (ESNII) will support three Generation IV reactor systems: a sodium-cooled fast reactor, or SFR, called ''Astrid'' that is proposed by France; a gas-cooled fast reactor, GFR, called ''Allegro'' supported by central and eastern Europe; and a lead-cooled fast reactor, LFR, technology pilot called ''Myrrha'' that is proposed by Belgium. |deadurl=yes |archiveurl=https://web.archive.org/web/20131009042600/http://euronuclear.org/1-information/news/Gen-IV.htm |archivedate=2013-10-09 |df= }}</ref> The central European [[Visegrád Group]] are committed to pursuing the technology.<ref>{{cite web |url=http://www.alphagalileo.org/ViewItem.aspx?ItemId=133111&CultureCode=en |title=The V4G4 Centre of Excellence for performing joint research, development and innovation in the field of Generation-4 (G4) nuclear reactors have been established. 20 July 2013 National Center for Nuclear Research (NCBJ)}}</ref> In 2013 German, British, and French institutes finished a 3-year collaboration study on the follow on industrial scale design, known as ''GoFastR''.<ref>{{cite web|url=http://www.ist-world.org/ProjectDetails.aspx?ProjectId=5cb8f3f283574cc6b2bdbf72533172d8 |title=the European Gas cooled Fast Reactor. |deadurl=yes |archiveurl=https://web.archive.org/web/20131213091046/http://www.ist-world.org/ProjectDetails.aspx?ProjectId=5cb8f3f283574cc6b2bdbf72533172d8 |archivedate=2013-12-13 |df= }}</ref> They were funded by the EU's 7th FWP [[framework programme]], with the goal of making a sustainable VHTR.<ref>{{cite web |url=http://www.2020-horizon.com/GOFASTR-European-Gas-Cooled-Fast-Reactor%28GOFASTR%29-s312.html |title=The GOFASTR research program}}</ref>

==== Sodium-cooled fast reactor (SFR) ====
[[File:Sodium-Cooled Fast Reactor Schemata.svg|right|thumb|Pool design Sodium-Cooled Fast Reactor (SFR)]]
{{Main article|Sodium-cooled fast reactor}}
{{see also|Prototype Fast Breeder Reactor|Experimental Breeder Reactor II|S-PRISM|BN-800 reactor|Toshiba 4S|CFR-600}}

In India, the [[Fast Breeder Test Reactor]] reached criticality in October 1985. In September 2002, fuel burn-up in the FBTR for the first time reached the 100,000 megawatt-days per metric ton uranium (MWd/MTU) mark. This is considered an important milestone in breeder reactor technology. Using the experience gained from the operation of the FBTR, the [[Prototype Fast Breeder Reactor]], a 500 MWe Sodium cooled fast reactor is being built at a cost of INR 5,677 crores (~US$900 million) and is expected to be critical by June 2018. The PFBR will be followed by six more Commercial Fast Breeder Reactors (CFBRs) of 600 MWe each.

The SFR<ref name="Roadmap"/> is a project that builds on two closely related existing projects, the liquid metal [[Breeder reactor#Fast breeder reactor|fast breeder reactor]] and the [[integral fast reactor]].

The goals are to increase the efficiency of uranium usage by [[breeder reactor|breeding]] plutonium and eliminating the need for [[transuranic]] isotopes ever to leave the site. The reactor design uses an unmoderated core running on [[fast neutron]]s, designed to allow any transuranic isotope to be consumed (and in some cases used as fuel). In addition to the benefits of removing the long [[half-life]] transuranics from the waste cycle, the SFR fuel expands when the reactor overheats, and the chain reaction automatically slows down. In this manner, it is passively safe.<ref>{{cite web |url=http://www.ne.anl.gov/About/hn/logos-winter02-psr.shtml|title=Passively safe reactors rely on nature to keep them cool|author=David Baurac}}</ref>

The SFR reactor concept is cooled by liquid [[sodium]] and fueled by a metallic alloy of uranium and [[plutonium]] or [[spent nuclear fuel]], the "nuclear waste" of [[light water reactor]]s. The SFR fuel is contained in steel cladding with liquid sodium filling in the space between the clad elements which make up the fuel assembly. One of the design challenges of an SFR is the risks of handling sodium, which reacts explosively if it comes into contact with water. However, the use of liquid metal instead of water as coolant allows the system to work at atmospheric pressure, reducing the risk of leakage.

The European Sustainable Nuclear Industrial Initiative is funding three Generation IV reactor systems, one of which is a sodium-cooled fast reactor, called ''[[ASTRID (reactor)|ASTRID]]'', Advanced Sodium Technical Reactor for Industrial Demonstration, [[Areva]], [[Commissariat à l'énergie atomique et aux énergies alternatives|CEA]] and [[Électricité de France|EDF]] are leading the design with British collaboration.<ref>{{cite web |url=http://www.power-eng.com/articles/2010/11/areva--cea-secure.html |title=Areva, CEA secure EUR650m funding to develop ASTRID sodium-cooled Generation IV reactor 11/11/2010}}</ref><ref>{{cite web |url=http://www.powermag.com/uk-and-france-sign-landmark-civil-nuclear-cooperation-agreement/ |title=UK and France Sign Landmark Civil Nuclear Cooperation Agreement 02/22/2012 . POWERnews}}</ref> Astrid will be rated about 600 MWe and is proposed to be built in France, near to the [[Phénix]] reactor. A final decision in construction is to be made in 2019<ref name="euronuclear.org"/>

The [[China|PRC]]'s first commercial-scale, 800 MWe, fast neutron reactor, to be situated near [[Sanming]] in [[Fujian province]] will be a SFR. In 2009 an agreement was signed that would entail the Russian [[BN-800 reactor]] design to be sold to the PRC once it is completed, this would be the first time commercial-scale fast neutron reactors have ever been exported.<ref>{{cite web |url=http://www.world-nuclear-news.org/C-Joint_venture_launched_for_Chinese_fast_reactor-3004104.html |title=Joint venture launched for Chinese fast reactor}}</ref> The BN-800 reactor became operational in 2014.

The 400 MWe [[Fast Flux Test Facility]] operated successfully for ten years at the Hanford site in Washington State.

The 20 MWe [[EBR II]] operated successfully for over thirty years at the Idaho National Laboratory, until it was shut down in 1994.

GE Hitachi's [[PRISM (reactor)|PRISM]] reactor is an SFR with the primary purpose of reducing the half lives of the fissionable elements present in used nuclear fuel while generating electricity largely as a by-product.

==== Lead-cooled fast reactor (LFR) ====
[[File:Lead-Cooled Fast Reactor Schemata.svg|right|thumb|Lead-Cooled Fast Reactor (LFR)]]
{{Main article|Lead-cooled fast reactor}}
{{See also|MYRRHA}}
The '''lead-cooled fast reactor'''<ref name="Roadmap">{{cite journal|year=2002 |title=A Technology Roadmap for Generation IV Nuclear Energy Systems |last=US DOE Nuclear Energy Research Advisory Committee |volume=GIF-002-00 |url=http://nuclear.energy.gov/genIV/documents/gen_iv_roadmap.pdf |deadurl=yes |archiveurl=https://web.archive.org/web/20071129121214/http://nuclear.energy.gov/genIV/documents/gen_iv_roadmap.pdf |archivedate=2007-11-29 |df= }}</ref> features a fast-neutron-spectrum [[lead]] or [[lead]]/[[bismuth]] [[eutectic]] ([[Lead-bismuth eutectic|LBE]]) liquid-metal-cooled reactor with a closed [[Nuclear fuel cycle|fuel cycle]]. Options include a range of plant ratings, including a "battery" of 50 to 150 MW of electricity that features a very long refueling interval, a modular system rated at 300 to 400 MW, and a large monolithic plant option at 1,200 MW (The term ''battery'' refers to the long-life, factory-fabricated core, not to any provision for electrochemical energy conversion). The fuel is metal or nitride-based containing [[Fertile material|fertile uranium]] and [[transuranic]]s. The LFR is cooled by natural [[convection]] with a reactor outlet coolant temperature of 550 °C, possibly ranging up to 800 °C with advanced materials. The higher temperature enables the production of [[Thermochemical cycle|hydrogen by thermochemical processes]].

The European Sustainable Nuclear Industrial Initiative is funding three Generation IV reactor systems, one of which is a lead-cooled fast reactor that is also an [[Subcritical reactor|accelerator-driven sub-critical]] reactor, called ''[[MYRRHA]]'', 100 MW(t), which will be built in [[Belgium]] with construction expected to begin after 2014 and the industrial scale version, known as ''Alfred'', slated to be constructed sometime after 2017. A reduced-power model of Myrrha called ''Guinevere'' was started up at [[Mol, Belgium|Mol]] in March 2009.<ref name="euronuclear.org"/> In 2012 the research team reported that Guinevere was operational.<ref>{{cite news|last1=Hellemans|first1=Alexander|title=Reactor-Accelerator Hybrid Achieves Successful Test Run|url=http://news.sciencemag.org/physics/2012/01/reactor-accelerator-hybrid-achieves-successful-test-run|accessdate=29 December 2014|work=Science Insider|date=12 January 2012}}</ref>

Two other lead-cooled fast reactors under development are the SVBR-100, a modular 100 MWe lead-bismuth cooled fast neutron reactor concept designed by OKB [[Gidropress]] in Russia and the [[BREST (Reactor)|BREST-OD-300]] (Lead-cooled fast reactor) 300 MWe, to be developed after the SVBR-100, and built over 2016-20, it will dispense with the [[Uranium-238|fertile blanket]] around the core and will supersede the sodium cooled [[BN-600 reactor]] design, to purportedly give enhanced proliferation resistance.<ref name="powertecrussia.com"/>

== Advantages and disadvantages ==
Relative to current nuclear power plant technology, the claimed benefits for 4th generation reactors include:
* Nuclear waste that remains radioactive for a few centuries instead of millennia<ref>{{cite web |title=Strategies to Address Global Warming |url=http://www.columbia.edu/~jeh1/mailings/2009/20090713_Strategies.pdf}}</ref>
* 100–300 times more energy yield from the same amount of nuclear fuel<ref>{{cite web |title=4th Generation Nuclear Power |url=http://www.ossfoundation.us/projects/energy/nuclear}}</ref>
* Broader range of fuels, and even unencapsulated raw fuels (non-pebble [[Molten Salt Reactor|MSR]], [[Liquid fluoride thorium reactor|LFTR]]).
* In some reactors, the ability to consume existing nuclear waste in the production of electricity, that is, a Closed [[nuclear fuel cycle]]. This strengthens the argument to deem [[nuclear power as renewable energy]].
* Improved operating safety features, such as (depending on design) avoidance of pressurized operation, automatic passive (unpowered, uncommanded) reactor shutdown, avoidance of water cooling and the associated risks of loss of water (leaks or boiling) and hydrogen generation/explosion and contamination of coolant water.

Nuclear reactors do not emit CO2 during operation, although like all [[low carbon power]] sources, the mining and construction phase can result in CO2 emissions, if energy sources which are not carbon neutral (such as fossil fuels), or CO2 emitting cements are used during the construction process.
A 2012 [[Yale University]] review published in the Journal of Industrial Ecology analyzing {{CO2}} [[life cycle assessment]] (LCA) emissions from [[nuclear power]] determined that:<ref name="Warner + Heath, JoIE">Warner, Ethan S.; Heath, Garvin A. [http://onlinelibrary.wiley.com/doi/10.1111/j.1530-9290.2012.00472.x/full Life Cycle Greenhouse Gas Emissions of Nuclear Electricity Generation: Systematic Review and Harmonization], ''Journal of Industrial Ecology'', [[Yale University]], published online April 17, 2012, {{doi|10.1111/j.1530-9290.2012.00472.x}}</ref>
{{Quote|The collective LCA literature indicates that life cycle [[Greenhouse gas|GHG]] [greenhouse gas] emissions from nuclear power are only a fraction of traditional fossil sources and comparable to renewable technologies.}}
Although the paper primarily dealt with data from [[Generation II reactor]]s, and did not analyze the {{CO2}} emissions by 2050 of the presently under construction [[Generation III reactor]]s, it did summarize the Life Cycle Assessment findings of in development reactor technologies.{{Quote|FBRs ['[[Fast Breeder Reactor]]s'] have been evaluated in the LCA literature. The limited literature that evaluates this potential future technology reports [[median]] life cycle GHG emissions... similar to or lower than LWRs [Gen II [[light water reactor]]s] and purports to consume little or no [[uranium market|uranium ore]].}}

A specific risk of the sodium-cooled fast reactor is related to using metallic sodium as a coolant. In case of a breach, sodium explosively reacts with water. Fixing breaches may also prove dangerous, as the cheapest noble gas [[argon]] is also used to prevent sodium oxidation. Argon, like helium, can displace oxygen in the air and can pose [[hypoxia (environmental)|hypoxia]] concerns, so workers may be exposed to this additional risk. This is a pertinent problem as demonstrated by the events at the [[LMFBR|loop type]] [[Monju Nuclear Power Plant|Prototype Fast Breeder Reactor Monju]] at Tsuruga, Japan.<ref>{{cite news |title=Japan Strains to Fix a Reactor Damaged Before Quake |url=https://www.nytimes.com/2011/06/18/world/asia/18japan.html | work=The New York Times | first=Hiroko |last=Tabuchi |date=17 June 2011}}</ref>
Using lead or molten salts mitigates this problem by making the coolant less reactive and allowing a high freezing temperature and low pressure in case of a leak. Disadvantages of lead compared to sodium are much higher viscosity, much higher density, lower heat capacity, and more radioactive neutron activation products.

In many cases, there is already a large amount of experience built up with numerous proof of concept Gen IV designs. For example, the reactors at [[Fort St. Vrain Generating Station]] and [[HTR-10]] are similar to the proposed Gen IV [[VHTR]] designs, and the [[LMFBR|pool type]] [[EBR-II]], [[Phénix]] and [[BN-600]] reactor are similar to the proposed pool type Gen IV Sodium Cooled Fast reactors being designed.

== Table of designs ==

{| class=wikitable
|+ Summary of designs for generation IV reactors<ref>https://www.gen-4.org/gif/upload/docs/application/pdf/2013-09/gif_rd_outlook_for_generation_iv_nuclear_energy_systems.pdf</ref>
|-
! System
! Neutron Spectrum
! Coolant
! Temperature (°C)
! Fuel Cycle
! Size (MW)
!Example developers
|-
| [[Very-high-temperature reactor|VHTR]]
| Thermal
| Helium
| 900–1000
| Open
| 250–300
|[[Japan Atomic Energy Agency|JAEA]] ([[High-temperature engineering test reactor|HTTR]]), [[Tsinghua University]] ([[HTR-10]]), [[X-energy]]<ref name="energy.gov">{{cite web|title=Energy Department Announces New Investments in Advanced Nuclear Power Reactors...|url=https://www.energy.gov/articles/energy-department-announces-new-investments-advanced-nuclear-power-reactors-help-meet|website=[[United States Department of Energy|US Department of Energy]]|accessdate=16 January 2016}}</ref>
|-
| [[Sodium-cooled fast reactor|SFR]]
| Fast
| Sodium
| 550
| Closed
| 30–150, 300–1500, 1000–2000
|[[TerraPower]] ([[Traveling wave reactor|TWR]]), [[Toshiba]] ([[Toshiba 4S|4S]]), [[GE Hitachi Nuclear Energy]] ([[PRISM (reactor)|PRISM]])
|-
| [[Supercritical water reactor|SCWR]]
| Thermal or fast
| Water
| 510–625
| Open or closed
| 300–700, 1000–1500
|
|-
| [[Gas-cooled fast reactor|GFR]]
| Fast
| Helium
| 850
| Closed
| 1200
|[[Energy Multiplier Module]]
|-
| [[Lead-cooled fast reactor|LFR]]
| Fast
| Lead
| 480–800
| Closed
| 20–180, 300–1200, 600–1000
|
|-
| [[Molten salt reactor|MSR]]
| Fast or thermal
| Fluoride or chloride salts
| 700–800
| Closed
| 250, 1000
|[[Seaborg Technologies]], [[TerraPower]], [[Stable Salt Reactor|Moltex Energy]], [[Flibe Energy]] ([[Liquid fluoride thorium reactor|LFTR]]), [[Transatomic Power]], Thorium Tech Solution ([[Fuji Molten Salt Reactor|FUJI MSR]]), Terrestrial Energy ([[IMSR]]), [[Southern Company Services|Southern Company]]<ref name="energy.gov"/>, [[Elysium Industries]]<ref>http://www.elysiumindustries.com/</ref>
|-
| [[Dual fluid reactor|DFR]]
| Fast
| Lead
| 1000
| Closed
| 500–1500
| Institute for Solid-State Nuclear Physics<ref name=ifk>{{cite web |url=https://festkoerper-kernphysik.de/dfr.pdf |title=Dual Fluid Reactor - IFK |date=2013-06-16 |website=festkoerper-kernphysik.de |publisher= Institut für Festkörper-Kernphysik |format=PDF |location=Berlin, Germany |access-date=2017-08-28}}</ref>, [[Aristos Power]] <ref name=HSR>{{|url=http://aristospower.tk |title=Hard Spectrum Reactor - HSR</ref>
|}

== See also ==
{{portal|Energy|Nuclear technology}}
{{colbegin}}
* [[Nuclear reactor]]
* [[Nuclear material]]
* [[Nuclear physics]]
* [[List of reactor types#Reactor types|List of reactor types]]
* [[Generation II reactor]]
* [[Generation III reactor]]
* [[Integral Fast Reactor]]
* [[Liquid fluoride thorium reactor]]
* [[Breeder reactor]]
* [[Small modular reactor]]
{{colend}}

==References==
{{Reflist|30em}}

== External links ==
* [https://inlportal.inl.gov/portal/server.pt?open=514&objID=1361&parentname=CommunityPage&parentid=10&mode=2&in_hi_userid=200&cached=true Article from Idaho National Laboratory detailing some current efforts at developing Gen. IV reactors.]
* [http://www.gen-4.org/ Generation IV International Forum (GIF)]
* [https://web.archive.org/web/20070205115654/http://nuclear.energy.gov/genIV/neGenIV1.html U.S. Department of Energy Office of Nuclear Energy, Science and Technology]
* [https://web.archive.org/web/20060512033030/http://www.engr.utk.edu/nuclear/colloquia/slides/Gen%20IV%20U-Tenn%20Presentation.pdf Gen IV presentation]
* [http://www.ecology.at/ecology/files/pr577_1.pdf Science or Fiction - Is there a Future for Nuclear?] (Nov. 2007) - A publication from the Austrian [[Ecology Institute (Austria)|Ecology Institute]] about 'Generation IV' and Fusion reactors.
* {{cite web |url=http://memagazine.asme.org/Articles/2011/December/Nuclear_Power_After_Fukushima.cfm |title=Nuclear Power After Fukushima |author=Gail H. Marcus |date=December 2011 |work=Mechanical Engineering (the magazine of [[ASME]]) |accessdate=23 January 2012}} "In the wake of a severe plant accident, advanced reactor designs are getting renewed attention."
* [http://www.itheo.org/ International Thorium Energy Organisation - www.IThEO.org]
* [http://www.ithec.org/ International Thorium Energy Committee - iThEC]

{{Nuclear fission reactors}}

[[Category:Nuclear power reactor types]]
[[Category:Idaho National Laboratory]]

Benutzer:Snackroeg/Kernreaktoren der Generation 5

2018-02-25T05:30:29Z

Boundarylayer:

{{update|date=October 2017}}
[[File:GenIVRoadmap-en.svg|thumb|480px|Nuclear Energy Systems Deployable no later than 2030 and offering significant advances in sustainability, safety and reliability, and economics]]

'''Generation IV reactors''' ('''Gen IV''') are a set of [[nuclear reactor]] designs currently being researched for commercial applications by the Generation IV International Forum, with [[Technology readiness level]]s varying between the level requiring a demonstration, to economical competitive implementation.<ref>{{Cite journal|last=Locatelli|first=Giorgio|last2=Mancini|first2=Mauro|last3=Todeschini|first3=Nicola|date=2013-10-01|title=Generation IV nuclear reactors: Current status and future prospects|url=http://www.sciencedirect.com/science/article/pii/S0301421513006083|journal=Energy Policy|volume=61|pages=1503–1520|doi=10.1016/j.enpol.2013.06.101}}</ref> They are motivated by a variety of goals including improved safety, sustainability, efficiency, and cost.

The most developed Gen IV reactor design, the [[sodium fast reactor]], has received the greatest share of funding over the years, with the principle Gen IV aspect of the design, relating in largest part to the development of a sustainable [[nuclear fuel cycle|closed fuel cycle]] for the reactor. Amongst nuclear engineers the [[molten-salt reactor]], the least developed and funded technology, is the safest of the six models.<ref>[https://www.scientificamerican.com/article/can-sodium-save-nuclear-power/ Can Sodium Save Nuclear Power? Scientific American]</ref>

The majority of the 6 designs are generally not expected to be available for commercial construction until 2020–30.<ref name="Generation IV">[http://www.world-nuclear.org/info/Nuclear-Fuel-Cycle/Power-Reactors/Generation-IV-Nuclear-Reactors/]</ref> Presently the majority of reactors in operation around the world are considered [[Generation II reactor|second generation reactor]] systems, as the vast majority of the [[Nuclear reactor#Classification by generation|first generation]] systems were retired some time ago, and there are only a dozen or so [[Generation III reactor]]s in operation as of 2014.
[[Nuclear reactor#Generation V+ reactors|Generation V reactors]] refer to reactors that are purely theoretical and are therefore not yet considered feasible in the short term, resulting in limited [[R&D]] funding.

== History ==
The Generation IV International Forum (GIF) is "a co-operative international endeavour which was set up to carry out the research and development needed to establish the feasibility and performance capabilities of the next generation nuclear energy systems."<ref>{{Cite web|url=https://www.gen-4.org/gif/jcms/c_9260/public|title=GIF Portal - Home - Public|website=www.gen-4.org|access-date=2016-07-25}}</ref> It was founded in 2001. Currently active members of the Generation IV International Forum (GIF) include: [[Australia]], [[Canada]], [[China]], the [[European Atomic Energy Community]] (Euratom), [[France]], [[Japan]], [[Russia]], [[South Africa]], [[South Korea]], [[Switzerland]], and the [[United States]]. The non-active members are [[Argentina]], [[Brazil]], and the [[United Kingdom]].<ref name="gen-4">{{cite web|url=https://www.gen-4.org/gif/jcms/c_9492/members|title=GIF Membership|website=gen-4.org|accessdate=28 October 2014}}</ref> Switzerland joined in 2002, Euratom in 2003, and China and Russia in 2006. The remaining countries (excluding Australia) were founding members.<ref name="gen-4" />

The 36th GIF meeting in [[Brussels]] was held in November 2013.<ref>{{cite web|url=https://www.energy.gov/ne/articles/generation-iv-international-forum-updates-technology-roadmap-and-builds-future|title=generation IV international forum updates technology roadmap and builds future. DOE}}</ref><ref>{{cite web|url=http://events.r20.constantcontact.com/register/event?llr=mscrkjkab&oeidk=a07e7melf609716b2c6 |title=The Generation IV international forum holds their 36th meeting on Monday 18th Nov 2013 in Brussels. }}{{dead link|date=January 2017 |bot=InternetArchiveBot |fix-attempted=yes }}</ref> The ''Technology Roadmap Update for Generation IV Nuclear Energy Systems'' was published in January 2014 which details R&D objectives for the next decade.<ref>[https://web.archive.org/web/20140625102915/https://www.gen-4.org/gif/upload/docs/application/pdf/2014-03/gif-tru2014.pdf Technology Roadmap Update for Generation IV Nuclear Energy Systems]</ref> A breakdown of the reactor designs being researched by each forum member has been made available.<ref>[https://web.archive.org/web/20140708023538/https://www.gen-4.org/gif/upload/docs/application/pdf/2014-03/gif_overview_presentation_v9_final3_web.pdf Generation IV International Forum, overview, John E. Kelly, page 15]</ref>

[[Nuclear power in Australia|Australia]] joined the forum in 2016.<ref>https://archive.is/20160907131656/https://www.gen-4.org/gif/jcms/c_71564/australia-joins-the-generation-iv-international-forum</ref>

In January 2018, it was reported that "the first installation of the pressure vessel cover of the world's first Gen IV reactor" had been completed on the [[HTR-PM]].<ref>http://www.world-nuclear-news.org/NN-First-HTR-PM-vessel-head-in-place-0401185.html</ref>

== Reactor types ==
Many reactor types were considered initially; however, the list was downsized to focus on the most promising technologies and those that could most likely meet the goals of the Gen IV initiative.<ref name="Generation IV"/> Three systems are nominally [[thermal reactor]]s and four are [[fast reactor]]s. The Very High Temperature Reactor (VHTR) is also being researched for potentially providing high quality process heat for [[thermochemical cycle|hydrogen production]]. The fast reactors offer the possibility of burning [[actinides]] to further reduce waste and of being able to "[[breeder reactor|breed more fuel]]" than they consume. These systems offer significant advances in sustainability, safety and reliability, economics, proliferation resistance (depending on perspective) and physical protection.

=== Thermal reactors ===
A [[Thermal-neutron reactor|thermal reactor]] is a [[nuclear reactor]] that uses slow or [[thermal neutrons]]. A [[neutron moderator]] is used to slow the [[neutron]]s emitted by fission to make them more likely to be captured by the fuel.

==== Very-high-temperature reactor (VHTR) ====
[[File:Very High Temperature Reactor.svg|right|thumb|Very-High-Temperature Reactor (VHTR)]]
{{Main article|Very high temperature reactor}}
{{see also|Fort St. Vrain Generating Station|High-temperature engineering test reactor|HTR-10}}
The '''very high temperature reactor''' concept uses a [[graphite]]-moderated core with a once-through [[uranium]] fuel cycle, using helium or molten salt as the [[Very high temperature reactor#Coolant|coolant]]. This reactor design envisions an outlet temperature of 1,000 °C. The reactor core can be either a prismatic-block or a [[pebble bed reactor]] design. The high temperatures enable applications such as process heat or [[hydrogen]] production via the thermochemical [[Sulfur-iodine cycle|iodine-sulfur]] process. It would also be [[Passive nuclear safety|passively safe]].

The planned construction of the first VHTR, the South African PBMR ([[pebble bed modular reactor]]), lost government funding in February, 2010.<ref>[http://www.powergenworldwide.com/index/display/articledisplay/6322207443/articles/power-engineering-international/volume-18/Issue_3/regulars/world-news/INTERNATIONAL.html South Africa to stop funding Pebble Bed nuclear reactor] {{webarchive|url=https://web.archive.org/web/20100909172743/http://www.powergenworldwide.com/index/display/articledisplay/6322207443/articles/power-engineering-international/volume-18/Issue_3/regulars/world-news/INTERNATIONAL.html |date=2010-09-09 }}</ref> A pronounced increase of costs and concerns about possible unexpected technical problems had discouraged potential investors and customers.

The [[Peoples Republic of China]] began construction of a 200-MW High Temperature Pebble bed reactor in 2012 as a successor to its [[HTR-10]].<ref>[http://www.nucnet.org/all-the-news/2013/01/07/china-begins-construction-of-first-generation-iv-htr-pm-unit Nucnet Report: 'China Begins Construction of First Generation IV HTR-PM Unit', 7 January 2013]</ref>

Also in 2012, as part of the [[Next Generation Nuclear Plant]] competition, [[Idaho National Laboratory]] approved a design similar to [[Areva]]'s prismatic block [http://us.areva.com/EN/home-3225/areva-inc-areva-htgr.html Antares reactor] as the chosen [[HTGR]] to be deployed as a prototype by 2021. It was in competition with [[General Atomics]]' [[Gas turbine modular helium reactor]] and [[Westinghouse Electric Company|Westinghouse]]'s [[Pebble Bed Modular Reactor]].<ref name="World nuclear news">{{cite web|url=http://www.world-nuclear-news.org/NN-Areva_modular_reactor_selected_for_NGNP_development-1502124.html|title=INL approves Antares design}}</ref>

[[X-energy]] was awarded a five-year $53M U.S. Department of Energy Advanced Reactor Concept Cooperative Agreement award to advance elements of their reactor development.<ref>[https://www.x-energy.com/doe-partnership]</ref>
The [[X-energy#Reactor Design|Xe-100]] is a pebble-bed modular reactor and will generate 200-MWt and approximately 76-MWe. The standard Xe-100 "four-pack" plant generates approximately 300-MWe and will fit on as few as 13 acres. All of the components for the Xe-100 will be road-transportable, and will be installed, rather than constructed, at the project site to streamline construction.<ref name="X-energy">{{cite web|url=https://www.x-energy.com/}}</ref>

==== Molten-salt reactor (MSR) ====
[[File:Molten Salt Reactor.svg|right|thumb|Molten Salt Reactor (MSR)]]
{{Main article|Molten salt reactor}}
{{see also|Liquid fluoride thorium reactor}}
A '''molten salt reactor'''<ref name="Roadmap"/> is a type of [[nuclear reactor]] where the primary [[coolant]], or even the fuel itself is a molten salt mixture. There have been many designs put forward for this type of reactor and a few prototypes built. The early concepts and many current ones rely on [[nuclear fuel]], perhaps [[uranium tetrafluoride]] (UF4) or [[thorium tetrafluoride]] (ThF4), dissolved in molten [[fluoride]] salt. The fluid would reach [[Nuclear reactor physics#Criticality|criticality]] by flowing into a core where [[graphite]] would serve as the [[neutron moderator|moderator]]. Many current concepts rely on fuel that is dispersed in a graphite matrix with the molten salt providing low pressure, high temperature cooling.

The Gen IV MSR is more accurately termed an [[epithermal neutron|epithermal reactor]] than a thermal reactor due to the average speed of the neutrons that would cause the fission events within its fuel being faster than [[thermal neutron]]s.<ref>{{cite web |url=https://inlportal.inl.gov/portal/server.pt?open=514&objID=1361&parentname=CommunityPage&parentid=10&mode=2&in_hi_userid=200&cached=true |title=Idaho National Laboratory detailing some current efforts at developing Gen. IV reactors}}</ref>

The principle of a MSR can be used for thermal, epithermal and fast reactors. Since 2005 the focus has moved towards a fast spectrum MSR (MSFR).<ref>H. Boussier, S. Delpech, V. Ghetta et Al. : The Molten Salt Reactor (MSR) in Generation IV: Overview and Perspectives, GIF SYMPOSIUM PROCEEDINGS/2012 ANNUAL REPORT, NEA No. 7141, pp95 [https://www.gen-4.org/gif/jcms/c_44720/annual-reports]
</ref>

While most MSR designs being pursued are largely derived from the 1960s [[Molten-Salt Reactor Experiment]](MSRE), variants of molten salt technology include the conceptual ''[[Dual fluid reactor]]'' which is being designed with lead as a cooling medium but molten salt fuel, commonly as the metal chloride e.g. [[Plutonium(III) chloride]], to aid in greater "nuclear waste" closed-fuel cycle capabilities.
Other notable approaches differing substantially from MSRE include the ''[[Stable Salt Reactor]]''(SSR) concept promoted by MOLTEX, which encases the molten salt in hundreds of the common solid [[fuel rod]]s that are already well established in the nuclear industry. This latter British design was found to be the most competitive for [[Small modular reactor]] development by a British-based consultancy firm ''Energy Process Development'' in 2015.<ref>[http://www.daretothink.org/europe-moltex-stable-salt-reactor/ Europe: Moltex’ Stable Salt Reactor]</ref><ref>[http://analysis.nuclearenergyinsider.com/moltex-energy-sees-uk-canada-smr-licensing-springboard-asia Moltex Energy sees UK, Canada SMR licensing as springboard to Asia Jun 28, 2016]</ref>

Another notable feature of the MSR is the possibility of a [[Thermal-neutron reactor|thermal spectrum]] nuclear [[Nuclear fuel cycle#Fuel cycles|waste-burner]]. Conventionally only fast spectrum reactors have been considered viable for [[Nuclear fuel cycle#Minor actinides recycling|utilization or reduction]] of the [[Spent nuclear fuel|spent nuclear stockpiles]]. The conceptual viability of a thermal waste-burner was first shown in a whitepaper by [[Seaborg Technologies]] spring 2015.<ref name="Seaborg Whitepaper 2015">{{cite web|url=https://seaborg.dk/s/Seaborg-whitepaper-2015.pdf|title=Thermal MSR waste burner benchmark}}</ref> Thermal waste-burning was achieved by replacing a fraction of the [[uranium]] in the spent nuclear fuel with [[thorium]]. The net production rate of [[transuranium element]] (e.g. [[plutonium]] and [[americium]]) is reduced below the consumption rate, thus reducing the magnitude of the [[Radioactive waste|nuclear storage problem]]. Without the [[nuclear proliferation]] concerns and other [[Fast-neutron reactor#Disadvantages|technical issues]] associated with a [[Fast-neutron reactor|fast reactor]].

==== Supercritical-water-cooled reactor (SCWR) ====
[[File:Supercritical-Water-Cooled Reactor.svg|right|thumb|Supercritical-Water-Cooled Reactor (SCWR)]]
{{Main article|Supercritical water reactor}}
The '''supercritical water reactor''' (SCWR)<ref name="Roadmap"/> is a [[reduced moderation water reactor]] concept that, due to the average speed of the neutrons that would cause the fission events within the fuel being faster than [[thermal neutron]]s, it is more accurately termed an [[epithermal neutron|epithermal reactor]] than a thermal reactor. It uses [[supercritical fluid|supercritical water]] as the working fluid. SCWRs are basically [[light water reactor]]s (LWR) operating at higher pressure and temperatures with a direct, once-through heat exchange cycle. As most commonly envisioned, it would operate on a direct cycle, much like a boiling water reactor ([[BWR]]), but since it uses supercritical water (not to be confused with [[Critical mass (nuclear)|critical mass]]) as the working fluid, it would have only one water phase present, which makes the supercritical heat exchange method more similar to a pressurized water reactor ([[Pressurized water reactor|PWR]]). It could operate at much higher temperatures than both current PWRs and BWRs.

Supercritical water-cooled reactors (SCWRs) are promising advanced nuclear systems because of their high [[thermal efficiency]] (i.e., about 45% vs. about 33% efficiency for current LWRs) and considerable plant simplification.

The main mission of the SCWR is generation of low-cost [[electricity]]. It is built upon two proven technologies, LWRs, which are the most commonly deployed power generating reactors in the world, and superheated [[fossil fuel]] fired [[boiler]]s, a large number of which are also in use around the world. The SCWR concept is being investigated by 32 organizations in 13 countries.{{citation needed|date=October 2012}}

Because SCWRs are water reactors they share the steam explosion and radioactive steam release hazards of BWRs and LWRs as well as the need for extremely expensive heavy duty pressure vessels, pipes, valves, and pumps. These shared problems are inherently more severe for SCWRs due to operation at higher temperatures.

A SCWR Design under development is the [[VVER]]-1700/393 (VVER-SCWR or VVER-SKD) — a Russian Supercritical-water-cooled reactor with double-inlet-core and a [[breeder reactor|breeding ratio]] of 0.95.<ref name="powertecrussia.com">{{cite web |url=http://www.powertecrussia.com/blog/tag/nuclear-power/ |title=Technology Developments & Plant Efficiency for the Russian Nuclear Power Generation Market Wednesday |date=March 24, 2010}}</ref>

=== Fast reactors ===
A [[Fast-neutron reactor|fast reactor]] directly uses the fast neutrons emitted by fission, without moderation. Unlike thermal neutron reactors, fast neutron reactors can be configured to "'''burn'''", or fission, all [[actinides]], and given enough time, therefore drastically reduce the actinides fraction in [[spent nuclear fuel]] produced by the present world fleet of thermal neutron [[light water reactor]]s, thus closing the [[nuclear fuel cycle]]. Alternatively, if configured differently, they can also [[breeder reactor|'''breed''']] more actinide fuel than they consume.

==== Gas-cooled fast reactor (GFR) ====
[[File:Gas-Cooled Fast Reactor Schemata.svg|right|thumb|Gas-Cooled Fast Reactor (GFR)]]
{{Main article|Gas-cooled fast reactor}}
The '''gas-cooled fast reactor''' (GFR)<ref name="Roadmap"/> system features a fast-neutron spectrum and closed fuel cycle for efficient conversion of [[Fertile material|fertile uranium]] and management of actinides. The reactor is [[helium]]-cooled and with an outlet temperature of 850 °C it is an evolution of the [[very-high-temperature reactor]] (VHTR) to a more sustainable fuel cycle. It will use a direct [[Brayton cycle]] [[Closed-cycle gas turbine|gas turbine]] for high thermal efficiency. Several fuel forms are being considered for their potential to operate at very high temperatures and to ensure an excellent retention of [[Nuclear fission|fission]] products: composite [[ceramic]] fuel, advanced fuel particles, or ceramic clad elements of actinide compounds. Core configurations are being considered based on pin- or plate-based fuel assemblies or prismatic blocks.

The European Sustainable Nuclear Industrial Initiative is funding three Generation IV reactor systems, one of which is a gas-cooled fast reactor, called ''Allegro'', 100 MW(t), which will be built in a central or eastern European country with construction expected to begin in 2018.<ref name="euronuclear.org">{{cite web|url=https://www.euronuclear.org/1-information/news/Gen-IV.htm |title=The European Sustainable Nuclear Industrial Initiative (ESNII) will support three Generation IV reactor systems: a sodium-cooled fast reactor, or SFR, called ''Astrid'' that is proposed by France; a gas-cooled fast reactor, GFR, called ''Allegro'' supported by central and eastern Europe; and a lead-cooled fast reactor, LFR, technology pilot called ''Myrrha'' that is proposed by Belgium. |deadurl=yes |archiveurl=https://web.archive.org/web/20131009042600/http://euronuclear.org/1-information/news/Gen-IV.htm |archivedate=2013-10-09 |df= }}</ref> The central European [[Visegrád Group]] are committed to pursuing the technology.<ref>{{cite web |url=http://www.alphagalileo.org/ViewItem.aspx?ItemId=133111&CultureCode=en |title=The V4G4 Centre of Excellence for performing joint research, development and innovation in the field of Generation-4 (G4) nuclear reactors have been established. 20 July 2013 National Center for Nuclear Research (NCBJ)}}</ref> In 2013 German, British, and French institutes finished a 3-year collaboration study on the follow on industrial scale design, known as ''GoFastR''.<ref>{{cite web|url=http://www.ist-world.org/ProjectDetails.aspx?ProjectId=5cb8f3f283574cc6b2bdbf72533172d8 |title=the European Gas cooled Fast Reactor. |deadurl=yes |archiveurl=https://web.archive.org/web/20131213091046/http://www.ist-world.org/ProjectDetails.aspx?ProjectId=5cb8f3f283574cc6b2bdbf72533172d8 |archivedate=2013-12-13 |df= }}</ref> They were funded by the EU's 7th FWP [[framework programme]], with the goal of making a sustainable VHTR.<ref>{{cite web |url=http://www.2020-horizon.com/GOFASTR-European-Gas-Cooled-Fast-Reactor%28GOFASTR%29-s312.html |title=The GOFASTR research program}}</ref>

==== Sodium-cooled fast reactor (SFR) ====
[[File:Sodium-Cooled Fast Reactor Schemata.svg|right|thumb|Pool design Sodium-Cooled Fast Reactor (SFR)]]
{{Main article|Sodium-cooled fast reactor}}
{{see also|Prototype Fast Breeder Reactor|Experimental Breeder Reactor II|S-PRISM|BN-800 reactor|Toshiba 4S|CFR-600}}

In India, the [[Fast Breeder Test Reactor]] reached criticality in October 1985. In September 2002, fuel burn-up in the FBTR for the first time reached the 100,000 megawatt-days per metric ton uranium (MWd/MTU) mark. This is considered an important milestone in breeder reactor technology. Using the experience gained from the operation of the FBTR, the [[Prototype Fast Breeder Reactor]], a 500 MWe Sodium cooled fast reactor is being built at a cost of INR 5,677 crores (~US$900 million) and is expected to be critical by June 2018. The PFBR will be followed by six more Commercial Fast Breeder Reactors (CFBRs) of 600 MWe each.

The SFR<ref name="Roadmap"/> is a project that builds on two closely related existing projects, the liquid metal [[Breeder reactor#Fast breeder reactor|fast breeder reactor]] and the [[integral fast reactor]].

The goals are to increase the efficiency of uranium usage by [[breeder reactor|breeding]] plutonium and eliminating the need for [[transuranic]] isotopes ever to leave the site. The reactor design uses an unmoderated core running on [[fast neutron]]s, designed to allow any transuranic isotope to be consumed (and in some cases used as fuel). In addition to the benefits of removing the long [[half-life]] transuranics from the waste cycle, the SFR fuel expands when the reactor overheats, and the chain reaction automatically slows down. In this manner, it is passively safe.<ref>{{cite web |url=http://www.ne.anl.gov/About/hn/logos-winter02-psr.shtml|title=Passively safe reactors rely on nature to keep them cool|author=David Baurac}}</ref>

The SFR reactor concept is cooled by liquid [[sodium]] and fueled by a metallic alloy of uranium and [[plutonium]] or [[spent nuclear fuel]], the "nuclear waste" of [[light water reactor]]s. The SFR fuel is contained in steel cladding with liquid sodium filling in the space between the clad elements which make up the fuel assembly. One of the design challenges of an SFR is the risks of handling sodium, which reacts explosively if it comes into contact with water. However, the use of liquid metal instead of water as coolant allows the system to work at atmospheric pressure, reducing the risk of leakage.

The European Sustainable Nuclear Industrial Initiative is funding three Generation IV reactor systems, one of which is a sodium-cooled fast reactor, called ''[[ASTRID (reactor)|ASTRID]]'', Advanced Sodium Technical Reactor for Industrial Demonstration, [[Areva]], [[Commissariat à l'énergie atomique et aux énergies alternatives|CEA]] and [[Électricité de France|EDF]] are leading the design with British collaboration.<ref>{{cite web |url=http://www.power-eng.com/articles/2010/11/areva--cea-secure.html |title=Areva, CEA secure EUR650m funding to develop ASTRID sodium-cooled Generation IV reactor 11/11/2010}}</ref><ref>{{cite web |url=http://www.powermag.com/uk-and-france-sign-landmark-civil-nuclear-cooperation-agreement/ |title=UK and France Sign Landmark Civil Nuclear Cooperation Agreement 02/22/2012 . POWERnews}}</ref> Astrid will be rated about 600 MWe and is proposed to be built in France, near to the [[Phénix]] reactor. A final decision in construction is to be made in 2019<ref name="euronuclear.org"/>

The [[China|PRC]]'s first commercial-scale, 800 MWe, fast neutron reactor, to be situated near [[Sanming]] in [[Fujian province]] will be a SFR. In 2009 an agreement was signed that would entail the Russian [[BN-800 reactor]] design to be sold to the PRC once it is completed, this would be the first time commercial-scale fast neutron reactors have ever been exported.<ref>{{cite web |url=http://www.world-nuclear-news.org/C-Joint_venture_launched_for_Chinese_fast_reactor-3004104.html |title=Joint venture launched for Chinese fast reactor}}</ref> The BN-800 reactor became operational in 2014.

The 400 MWe [[Fast Flux Test Facility]] operated successfully for ten years at the Hanford site in Washington State.

The 20 MWe [[EBR II]] operated successfully for over thirty years at the Idaho National Laboratory, until it was shut down in 1994.

GE Hitachi's [[PRISM (reactor)|PRISM]] reactor is an SFR with the primary purpose of reducing the half lives of the fissionable elements present in used nuclear fuel while generating electricity largely as a by-product.

==== Lead-cooled fast reactor (LFR) ====
[[File:Lead-Cooled Fast Reactor Schemata.svg|right|thumb|Lead-Cooled Fast Reactor (LFR)]]
{{Main article|Lead-cooled fast reactor}}
{{See also|MYRRHA}}
The '''lead-cooled fast reactor'''<ref name="Roadmap">{{cite journal|year=2002 |title=A Technology Roadmap for Generation IV Nuclear Energy Systems |last=US DOE Nuclear Energy Research Advisory Committee |volume=GIF-002-00 |url=http://nuclear.energy.gov/genIV/documents/gen_iv_roadmap.pdf |deadurl=yes |archiveurl=https://web.archive.org/web/20071129121214/http://nuclear.energy.gov/genIV/documents/gen_iv_roadmap.pdf |archivedate=2007-11-29 |df= }}</ref> features a fast-neutron-spectrum [[lead]] or [[lead]]/[[bismuth]] [[eutectic]] ([[Lead-bismuth eutectic|LBE]]) liquid-metal-cooled reactor with a closed [[Nuclear fuel cycle|fuel cycle]]. Options include a range of plant ratings, including a "battery" of 50 to 150 MW of electricity that features a very long refueling interval, a modular system rated at 300 to 400 MW, and a large monolithic plant option at 1,200 MW (The term ''battery'' refers to the long-life, factory-fabricated core, not to any provision for electrochemical energy conversion). The fuel is metal or nitride-based containing [[Fertile material|fertile uranium]] and [[transuranic]]s. The LFR is cooled by natural [[convection]] with a reactor outlet coolant temperature of 550 °C, possibly ranging up to 800 °C with advanced materials. The higher temperature enables the production of [[Thermochemical cycle|hydrogen by thermochemical processes]].

The European Sustainable Nuclear Industrial Initiative is funding three Generation IV reactor systems, one of which is a lead-cooled fast reactor that is also an [[Subcritical reactor|accelerator-driven sub-critical]] reactor, called ''[[MYRRHA]]'', 100 MW(t), which will be built in [[Belgium]] with construction expected to begin after 2014 and the industrial scale version, known as ''Alfred'', slated to be constructed sometime after 2017. A reduced-power model of Myrrha called ''Guinevere'' was started up at [[Mol, Belgium|Mol]] in March 2009.<ref name="euronuclear.org"/> In 2012 the research team reported that Guinevere was operational.<ref>{{cite news|last1=Hellemans|first1=Alexander|title=Reactor-Accelerator Hybrid Achieves Successful Test Run|url=http://news.sciencemag.org/physics/2012/01/reactor-accelerator-hybrid-achieves-successful-test-run|accessdate=29 December 2014|work=Science Insider|date=12 January 2012}}</ref>

Two other lead-cooled fast reactors under development are the SVBR-100, a modular 100 MWe lead-bismuth cooled fast neutron reactor concept designed by OKB [[Gidropress]] in Russia and the [[BREST (Reactor)|BREST-OD-300]] (Lead-cooled fast reactor) 300 MWe, to be developed after the SVBR-100, and built over 2016-20, it will dispense with the [[Uranium-238|fertile blanket]] around the core and will supersede the sodium cooled [[BN-600 reactor]] design, to purportedly give enhanced proliferation resistance.<ref name="powertecrussia.com"/>

== Advantages and disadvantages ==
Relative to current nuclear power plant technology, the claimed benefits for 4th generation reactors include:
* Nuclear waste that remains radioactive for a few centuries instead of millennia<ref>{{cite web |title=Strategies to Address Global Warming |url=http://www.columbia.edu/~jeh1/mailings/2009/20090713_Strategies.pdf}}</ref>
* 100–300 times more energy yield from the same amount of nuclear fuel<ref>{{cite web |title=4th Generation Nuclear Power |url=http://www.ossfoundation.us/projects/energy/nuclear}}</ref>
* Broader range of fuels, and even unencapsulated raw fuels (non-pebble [[Molten Salt Reactor|MSR]], [[Liquid fluoride thorium reactor|LFTR]]).
* In some reactors, the ability to consume existing nuclear waste in the production of electricity, that is, a Closed [[nuclear fuel cycle]]. This strengthens the argument to deem [[nuclear power as renewable energy]].
* Improved operating safety features, such as (depending on design) avoidance of pressurized operation, automatic passive (unpowered, uncommanded) reactor shutdown, avoidance of water cooling and the associated risks of loss of water (leaks or boiling) and hydrogen generation/explosion and contamination of coolant water.

Nuclear reactors do not emit CO2 during operation, although like all [[low carbon power]] sources, the mining and construction phase can result in CO2 emissions, if energy sources which are not carbon neutral (such as fossil fuels), or CO2 emitting cements are used during the construction process.
A 2012 [[Yale University]] review published in the Journal of Industrial Ecology analyzing {{CO2}} [[life cycle assessment]] (LCA) emissions from [[nuclear power]] determined that:<ref name="Warner + Heath, JoIE">Warner, Ethan S.; Heath, Garvin A. [http://onlinelibrary.wiley.com/doi/10.1111/j.1530-9290.2012.00472.x/full Life Cycle Greenhouse Gas Emissions of Nuclear Electricity Generation: Systematic Review and Harmonization], ''Journal of Industrial Ecology'', [[Yale University]], published online April 17, 2012, {{doi|10.1111/j.1530-9290.2012.00472.x}}</ref>
{{Quote|The collective LCA literature indicates that life cycle [[Greenhouse gas|GHG]] [greenhouse gas] emissions from nuclear power are only a fraction of traditional fossil sources and comparable to renewable technologies.}}
Although the paper primarily dealt with data from [[Generation II reactor]]s, and did not analyze the {{CO2}} emissions by 2050 of the presently under construction [[Generation III reactor]]s, it did summarize the Life Cycle Assessment findings of in development reactor technologies.{{Quote|FBRs ['[[Fast Breeder Reactor]]s'] have been evaluated in the LCA literature. The limited literature that evaluates this potential future technology reports [[median]] life cycle GHG emissions... similar to or lower than LWRs [Gen II [[light water reactor]]s] and purports to consume little or no [[uranium market|uranium ore]].}}

A specific risk of the sodium-cooled fast reactor is related to using metallic sodium as a coolant. In case of a breach, sodium explosively reacts with water. Fixing breaches may also prove dangerous, as the cheapest noble gas [[argon]] is also used to prevent sodium oxidation. Argon, like helium, can displace oxygen in the air and can pose [[hypoxia (environmental)|hypoxia]] concerns, so workers may be exposed to this additional risk. This is a pertinent problem as demonstrated by the events at the [[LMFBR|loop type]] [[Monju Nuclear Power Plant|Prototype Fast Breeder Reactor Monju]] at Tsuruga, Japan.<ref>{{cite news |title=Japan Strains to Fix a Reactor Damaged Before Quake |url=https://www.nytimes.com/2011/06/18/world/asia/18japan.html | work=The New York Times | first=Hiroko |last=Tabuchi |date=17 June 2011}}</ref>
Using lead or molten salts mitigates this problem by making the coolant less reactive and allowing a high freezing temperature and low pressure in case of a leak. Disadvantages of lead compared to sodium are much higher viscosity, much higher density, lower heat capacity, and more radioactive neutron activation products.

In many cases, there is already a large amount of experience built up with numerous proof of concept Gen IV designs. For example, the reactors at [[Fort St. Vrain Generating Station]] and [[HTR-10]] are similar to the proposed Gen IV [[VHTR]] designs, and the [[LMFBR|pool type]] [[EBR-II]], [[Phénix]] and [[BN-600]] reactor are similar to the proposed pool type Gen IV Sodium Cooled Fast reactors being designed.

== Table of designs ==

{| class=wikitable
|+ Summary of designs for generation IV reactors<ref>https://www.gen-4.org/gif/upload/docs/application/pdf/2013-09/gif_rd_outlook_for_generation_iv_nuclear_energy_systems.pdf</ref>
|-
! System
! Neutron Spectrum
! Coolant
! Temperature (°C)
! Fuel Cycle
! Size (MW)
!Example developers
|-
| [[Very-high-temperature reactor|VHTR]]
| Thermal
| Helium
| 900–1000
| Open
| 250–300
|[[Japan Atomic Energy Agency|JAEA]] ([[High-temperature engineering test reactor|HTTR]]), [[Tsinghua University]] ([[HTR-10]]), [[X-energy]]<ref name="energy.gov">{{cite web|title=Energy Department Announces New Investments in Advanced Nuclear Power Reactors...|url=https://www.energy.gov/articles/energy-department-announces-new-investments-advanced-nuclear-power-reactors-help-meet|website=[[United States Department of Energy|US Department of Energy]]|accessdate=16 January 2016}}</ref>
|-
| [[Sodium-cooled fast reactor|SFR]]
| Fast
| Sodium
| 550
| Closed
| 30–150, 300–1500, 1000–2000
|[[TerraPower]] ([[Traveling wave reactor|TWR]]), [[Toshiba]] ([[Toshiba 4S|4S]]), [[GE Hitachi Nuclear Energy]] ([[PRISM (reactor)|PRISM]])
|-
| [[Supercritical water reactor|SCWR]]
| Thermal or fast
| Water
| 510–625
| Open or closed
| 300–700, 1000–1500
|
|-
| [[Gas-cooled fast reactor|GFR]]
| Fast
| Helium
| 850
| Closed
| 1200
|[[Energy Multiplier Module]]
|-
| [[Lead-cooled fast reactor|LFR]]
| Fast
| Lead
| 480–800
| Closed
| 20–180, 300–1200, 600–1000
|
|-
| [[Molten salt reactor|MSR]]
| Fast or thermal
| Fluoride or chloride salts
| 700–800
| Closed
| 250, 1000
|[[Seaborg Technologies]], [[TerraPower]], [[Stable Salt Reactor|Moltex Energy]], [[Flibe Energy]] ([[Liquid fluoride thorium reactor|LFTR]]), [[Transatomic Power]], Thorium Tech Solution ([[Fuji Molten Salt Reactor|FUJI MSR]]), Terrestrial Energy ([[IMSR]]), [[Southern Company Services|Southern Company]]<ref name="energy.gov"/>, [[Elysium Industries]]<ref>http://www.elysiumindustries.com/</ref>
|-
| [[Dual fluid reactor|DFR]]
| Fast
| Lead
| 1000
| Closed
| 500–1500
| Institute for Solid-State Nuclear Physics<ref name=ifk>{{cite web |url=https://festkoerper-kernphysik.de/dfr.pdf |title=Dual Fluid Reactor - IFK |date=2013-06-16 |website=festkoerper-kernphysik.de |publisher= Institut für Festkörper-Kernphysik |format=PDF |location=Berlin, Germany |access-date=2017-08-28}}</ref>, [[Aristos Power]] <ref name=HSR>{{|url=http://aristospower.tk |title=Hard Spectrum Reactor - HSR</ref>
|}

== See also ==
{{portal|Energy|Nuclear technology}}
{{colbegin}}
* [[Nuclear reactor]]
* [[Nuclear material]]
* [[Nuclear physics]]
* [[List of reactor types#Reactor types|List of reactor types]]
* [[Generation II reactor]]
* [[Generation III reactor]]
* [[Integral Fast Reactor]]
* [[Liquid fluoride thorium reactor]]
* [[Breeder reactor]]
* [[Small modular reactor]]
{{colend}}

==References==
{{Reflist|30em}}

== External links ==
* [https://inlportal.inl.gov/portal/server.pt?open=514&objID=1361&parentname=CommunityPage&parentid=10&mode=2&in_hi_userid=200&cached=true Article from Idaho National Laboratory detailing some current efforts at developing Gen. IV reactors.]
* [http://www.gen-4.org/ Generation IV International Forum (GIF)]
* [https://web.archive.org/web/20070205115654/http://nuclear.energy.gov/genIV/neGenIV1.html U.S. Department of Energy Office of Nuclear Energy, Science and Technology]
* [https://web.archive.org/web/20060512033030/http://www.engr.utk.edu/nuclear/colloquia/slides/Gen%20IV%20U-Tenn%20Presentation.pdf Gen IV presentation]
* [http://www.ecology.at/ecology/files/pr577_1.pdf Science or Fiction - Is there a Future for Nuclear?] (Nov. 2007) - A publication from the Austrian [[Ecology Institute (Austria)|Ecology Institute]] about 'Generation IV' and Fusion reactors.
* {{cite web |url=http://memagazine.asme.org/Articles/2011/December/Nuclear_Power_After_Fukushima.cfm |title=Nuclear Power After Fukushima |author=Gail H. Marcus |date=December 2011 |work=Mechanical Engineering (the magazine of [[ASME]]) |accessdate=23 January 2012}} "In the wake of a severe plant accident, advanced reactor designs are getting renewed attention."
* [http://www.itheo.org/ International Thorium Energy Organisation - www.IThEO.org]
* [http://www.ithec.org/ International Thorium Energy Committee - iThEC]

{{Nuclear fission reactors}}

[[Category:Nuclear power reactor types]]
[[Category:Idaho National Laboratory]]

Benutzer:Snackroeg/Kernreaktoren der Generation 5

2018-02-09T14:33:10Z

Boundarylayer: /* Sodium-cooled fast reactor (SFR) */

{{update|date=October 2017}}
[[File:GenIVRoadmap-en.svg|thumb|480px|Nuclear Energy Systems Deployable no later than 2030 and offering significant advances in sustainability, safety and reliability, and economics]]

'''Generation IV reactors''' ('''Gen IV''') are a set of [[nuclear reactor]] designs currently being researched for commercial applications by the Generation IV International Forum, with [[Technology readiness level]]s varying between the level requiring a demonstration, to economical competitive implementation.<ref>{{Cite journal|last=Locatelli|first=Giorgio|last2=Mancini|first2=Mauro|last3=Todeschini|first3=Nicola|date=2013-10-01|title=Generation IV nuclear reactors: Current status and future prospects|url=http://www.sciencedirect.com/science/article/pii/S0301421513006083|journal=Energy Policy|volume=61|pages=1503–1520|doi=10.1016/j.enpol.2013.06.101}}</ref> They are motivated by a variety of goals including improved safety, sustainability, efficiency, and cost.

Most of these designs are generally not expected to be available for commercial construction until 2020–30.<ref name="Generation IV">[http://www.world-nuclear.org/info/Nuclear-Fuel-Cycle/Power-Reactors/Generation-IV-Nuclear-Reactors/]</ref> Presently the majority of reactors in operation around the world are considered [[Generation II reactor|second generation reactor]] systems, as the vast majority of the [[Nuclear reactor#Classification by generation|first generation]] systems were retired some time ago, and there are only a dozen or so [[Generation III reactor]]s in operation as of 2014.
[[Nuclear reactor#Generation V+ reactors|Generation V reactors]] refer to reactors that are purely theoretical and are therefore not yet considered feasible in the short term, resulting in limited [[R&D]] funding.

== History ==
The Generation IV International Forum (GIF) is "a co-operative international endeavour which was set up to carry out the research and development needed to establish the feasibility and performance capabilities of the next generation nuclear energy systems."<ref>{{Cite web|url=https://www.gen-4.org/gif/jcms/c_9260/public|title=GIF Portal - Home - Public|website=www.gen-4.org|access-date=2016-07-25}}</ref> It was founded in 2001. Currently active members of the Generation IV International Forum (GIF) include: [[Australia]], [[Canada]], [[China]], the [[European Atomic Energy Community]] (Euratom), [[France]], [[Japan]], [[Russia]], [[South Africa]], [[South Korea]], [[Switzerland]], and the [[United States]]. The non-active members are [[Argentina]], [[Brazil]], and the [[United Kingdom]].<ref name="gen-4">{{cite web|url=https://www.gen-4.org/gif/jcms/c_9492/members|title=GIF Membership|website=gen-4.org|accessdate=28 October 2014}}</ref> Switzerland joined in 2002, Euratom in 2003, and China and Russia in 2006. The remaining countries (excluding Australia) were founding members.<ref name="gen-4" />

The 36th GIF meeting in [[Brussels]] was held in November 2013.<ref>{{cite web|url=https://www.energy.gov/ne/articles/generation-iv-international-forum-updates-technology-roadmap-and-builds-future|title=generation IV international forum updates technology roadmap and builds future. DOE}}</ref><ref>{{cite web|url=http://events.r20.constantcontact.com/register/event?llr=mscrkjkab&oeidk=a07e7melf609716b2c6 |title=The Generation IV international forum holds their 36th meeting on Monday 18th Nov 2013 in Brussels. }}{{dead link|date=January 2017 |bot=InternetArchiveBot |fix-attempted=yes }}</ref> The ''Technology Roadmap Update for Generation IV Nuclear Energy Systems'' was published in January 2014 which details R&D objectives for the next decade.<ref>[https://web.archive.org/web/20140625102915/https://www.gen-4.org/gif/upload/docs/application/pdf/2014-03/gif-tru2014.pdf Technology Roadmap Update for Generation IV Nuclear Energy Systems]</ref> A breakdown of the reactor designs being researched by each forum member has been made available.<ref>[https://web.archive.org/web/20140708023538/https://www.gen-4.org/gif/upload/docs/application/pdf/2014-03/gif_overview_presentation_v9_final3_web.pdf Generation IV International Forum, overview, John E. Kelly, page 15]</ref>

[[Nuclear power in Australia|Australia]] joined the forum in 2016.<ref>https://archive.is/20160907131656/https://www.gen-4.org/gif/jcms/c_71564/australia-joins-the-generation-iv-international-forum</ref>

In January 2018, it was reported that "the first installation of the pressure vessel cover of the world's first Gen IV reactor" had been completed on the [[HTR-PM]].<ref>http://www.world-nuclear-news.org/NN-First-HTR-PM-vessel-head-in-place-0401185.html</ref>

== Reactor types ==
Many reactor types were considered initially; however, the list was downsized to focus on the most promising technologies and those that could most likely meet the goals of the Gen IV initiative.<ref name="Generation IV"/> Three systems are nominally [[thermal reactor]]s and four are [[fast reactor]]s. The Very High Temperature Reactor (VHTR) is also being researched for potentially providing high quality process heat for [[thermochemical cycle|hydrogen production]]. The fast reactors offer the possibility of burning [[actinides]] to further reduce waste and of being able to "[[breeder reactor|breed more fuel]]" than they consume. These systems offer significant advances in sustainability, safety and reliability, economics, proliferation resistance (depending on perspective) and physical protection.

=== Thermal reactors ===
A [[Thermal-neutron reactor|thermal reactor]] is a [[nuclear reactor]] that uses slow or [[thermal neutrons]]. A [[neutron moderator]] is used to slow the [[neutron]]s emitted by fission to make them more likely to be captured by the fuel.

==== Very-high-temperature reactor (VHTR) ====
[[File:Very High Temperature Reactor.svg|right|thumb|Very-High-Temperature Reactor (VHTR)]]
{{Main article|Very high temperature reactor}}
{{see also|Fort St. Vrain Generating Station|High-temperature engineering test reactor|HTR-10}}
The '''very high temperature reactor''' concept uses a [[graphite]]-moderated core with a once-through [[uranium]] fuel cycle, using helium or molten salt as the [[Very high temperature reactor#Coolant|coolant]]. This reactor design envisions an outlet temperature of 1,000 °C. The reactor core can be either a prismatic-block or a [[pebble bed reactor]] design. The high temperatures enable applications such as process heat or [[hydrogen]] production via the thermochemical [[Sulfur-iodine cycle|iodine-sulfur]] process. It would also be [[Passive nuclear safety|passively safe]].

The planned construction of the first VHTR, the South African PBMR ([[pebble bed modular reactor]]), lost government funding in February, 2010.<ref>[http://www.powergenworldwide.com/index/display/articledisplay/6322207443/articles/power-engineering-international/volume-18/Issue_3/regulars/world-news/INTERNATIONAL.html South Africa to stop funding Pebble Bed nuclear reactor] {{webarchive|url=https://web.archive.org/web/20100909172743/http://www.powergenworldwide.com/index/display/articledisplay/6322207443/articles/power-engineering-international/volume-18/Issue_3/regulars/world-news/INTERNATIONAL.html |date=2010-09-09 }}</ref> A pronounced increase of costs and concerns about possible unexpected technical problems had discouraged potential investors and customers.

The [[Peoples Republic of China]] began construction of a 200-MW High Temperature Pebble bed reactor in 2012 as a successor to its [[HTR-10]].<ref>[http://www.nucnet.org/all-the-news/2013/01/07/china-begins-construction-of-first-generation-iv-htr-pm-unit Nucnet Report: 'China Begins Construction of First Generation IV HTR-PM Unit', 7 January 2013]</ref>

Also in 2012, as part of the [[Next Generation Nuclear Plant]] competition, [[Idaho National Laboratory]] approved a design similar to [[Areva]]'s prismatic block [http://us.areva.com/EN/home-3225/areva-inc-areva-htgr.html Antares reactor] as the chosen [[HTGR]] to be deployed as a prototype by 2021. It was in competition with [[General Atomics]]' [[Gas turbine modular helium reactor]] and [[Westinghouse Electric Company|Westinghouse]]'s [[Pebble Bed Modular Reactor]].<ref name="World nuclear news">{{cite web|url=http://www.world-nuclear-news.org/NN-Areva_modular_reactor_selected_for_NGNP_development-1502124.html|title=INL approves Antares design}}</ref>

[[X-energy]] was awarded a five-year $53M U.S. Department of Energy Advanced Reactor Concept Cooperative Agreement award to advance elements of their reactor development.<ref>[https://www.x-energy.com/doe-partnership]</ref>
The [[X-energy#Reactor Design|Xe-100]] is a pebble-bed modular reactor and will generate 200-MWt and approximately 76-MWe. The standard Xe-100 "four-pack" plant generates approximately 300-MWe and will fit on as few as 13 acres. All of the components for the Xe-100 will be road-transportable, and will be installed, rather than constructed, at the project site to streamline construction.<ref name="X-energy">{{cite web|url=https://www.x-energy.com/}}</ref>

==== Molten-salt reactor (MSR) ====
[[File:Molten Salt Reactor.svg|right|thumb|Molten Salt Reactor (MSR)]]
{{Main article|Molten salt reactor}}
{{see also|Liquid fluoride thorium reactor}}
A '''molten salt reactor'''<ref name="Roadmap"/> is a type of [[nuclear reactor]] where the primary [[coolant]], or even the fuel itself is a molten salt mixture. There have been many designs put forward for this type of reactor and a few prototypes built. The early concepts and many current ones rely on [[nuclear fuel]], perhaps [[uranium tetrafluoride]] (UF4) or [[thorium tetrafluoride]] (ThF4), dissolved in molten [[fluoride]] salt. The fluid would reach [[Nuclear reactor physics#Criticality|criticality]] by flowing into a core where [[graphite]] would serve as the [[neutron moderator|moderator]]. Many current concepts rely on fuel that is dispersed in a graphite matrix with the molten salt providing low pressure, high temperature cooling.

The Gen IV MSR is more accurately termed an [[epithermal neutron|epithermal reactor]] than a thermal reactor due to the average speed of the neutrons that would cause the fission events within its fuel being faster than [[thermal neutron]]s.<ref>{{cite web |url=https://inlportal.inl.gov/portal/server.pt?open=514&objID=1361&parentname=CommunityPage&parentid=10&mode=2&in_hi_userid=200&cached=true |title=Idaho National Laboratory detailing some current efforts at developing Gen. IV reactors}}</ref>

The principle of a MSR can be used for thermal, epithermal and fast reactors. Since 2005 the focus has moved towards a fast spectrum MSR (MSFR).<ref>H. Boussier, S. Delpech, V. Ghetta et Al. : The Molten Salt Reactor (MSR) in Generation IV: Overview and Perspectives, GIF SYMPOSIUM PROCEEDINGS/2012 ANNUAL REPORT, NEA No. 7141, pp95 [https://www.gen-4.org/gif/jcms/c_44720/annual-reports]
</ref>

While most MSR designs being pursued are largely derived from the 1960s [[Molten-Salt Reactor Experiment]](MSRE), variants of molten salt technology include the conceptual ''[[Dual fluid reactor]]'' which is being designed with lead as a cooling medium but molten salt fuel, commonly as the metal chloride e.g. [[Plutonium(III) chloride]], to aid in greater "nuclear waste" closed-fuel cycle capabilities.
Other notable approaches differing substantially from MSRE include the ''[[Stable Salt Reactor]]''(SSR) concept promoted by MOLTEX, which encases the molten salt in hundreds of the common solid [[fuel rod]]s that are already well established in the nuclear industry. This latter British design was found to be the most competitive for [[Small modular reactor]] development by a British-based consultancy firm ''Energy Process Development'' in 2015.<ref>[http://www.daretothink.org/europe-moltex-stable-salt-reactor/ Europe: Moltex’ Stable Salt Reactor]</ref><ref>[http://analysis.nuclearenergyinsider.com/moltex-energy-sees-uk-canada-smr-licensing-springboard-asia Moltex Energy sees UK, Canada SMR licensing as springboard to Asia Jun 28, 2016]</ref>

Another notable feature of the MSR is the possibility of a [[Thermal-neutron reactor|thermal spectrum]] nuclear [[Nuclear fuel cycle#Fuel cycles|waste-burner]]. Conventionally only fast spectrum reactors have been considered viable for [[Nuclear fuel cycle#Minor actinides recycling|utilization or reduction]] of the [[Spent nuclear fuel|spent nuclear stockpiles]]. The conceptual viability of a thermal waste-burner was first shown in a whitepaper by [[Seaborg Technologies]] spring 2015.<ref name="Seaborg Whitepaper 2015">{{cite web|url=https://seaborg.dk/s/Seaborg-whitepaper-2015.pdf|title=Thermal MSR waste burner benchmark}}</ref> Thermal waste-burning was achieved by replacing a fraction of the [[uranium]] in the spent nuclear fuel with [[thorium]]. The net production rate of [[transuranium element]] (e.g. [[plutonium]] and [[americium]]) is reduced below the consumption rate, thus reducing the magnitude of the [[Radioactive waste|nuclear storage problem]]. Without the [[nuclear proliferation]] concerns and other [[Fast-neutron reactor#Disadvantages|technical issues]] associated with a [[Fast-neutron reactor|fast reactor]].

==== Supercritical-water-cooled reactor (SCWR) ====
[[File:Supercritical-Water-Cooled Reactor.svg|right|thumb|Supercritical-Water-Cooled Reactor (SCWR)]]
{{Main article|Supercritical water reactor}}
The '''supercritical water reactor''' (SCWR)<ref name="Roadmap"/> is a [[reduced moderation water reactor]] concept that, due to the average speed of the neutrons that would cause the fission events within the fuel being faster than [[thermal neutron]]s, it is more accurately termed an [[epithermal neutron|epithermal reactor]] than a thermal reactor. It uses [[supercritical fluid|supercritical water]] as the working fluid. SCWRs are basically [[light water reactor]]s (LWR) operating at higher pressure and temperatures with a direct, once-through heat exchange cycle. As most commonly envisioned, it would operate on a direct cycle, much like a boiling water reactor ([[BWR]]), but since it uses supercritical water (not to be confused with [[Critical mass (nuclear)|critical mass]]) as the working fluid, it would have only one water phase present, which makes the supercritical heat exchange method more similar to a pressurized water reactor ([[Pressurized water reactor|PWR]]). It could operate at much higher temperatures than both current PWRs and BWRs.

Supercritical water-cooled reactors (SCWRs) are promising advanced nuclear systems because of their high [[thermal efficiency]] (i.e., about 45% vs. about 33% efficiency for current LWRs) and considerable plant simplification.

The main mission of the SCWR is generation of low-cost [[electricity]]. It is built upon two proven technologies, LWRs, which are the most commonly deployed power generating reactors in the world, and superheated [[fossil fuel]] fired [[boiler]]s, a large number of which are also in use around the world. The SCWR concept is being investigated by 32 organizations in 13 countries.{{citation needed|date=October 2012}}

Because SCWRs are water reactors they share the steam explosion and radioactive steam release hazards of BWRs and LWRs as well as the need for extremely expensive heavy duty pressure vessels, pipes, valves, and pumps. These shared problems are inherently more severe for SCWRs due to operation at higher temperatures.

A SCWR Design under development is the [[VVER]]-1700/393 (VVER-SCWR or VVER-SKD) — a Russian Supercritical-water-cooled reactor with double-inlet-core and a [[breeder reactor|breeding ratio]] of 0.95.<ref name="powertecrussia.com">{{cite web |url=http://www.powertecrussia.com/blog/tag/nuclear-power/ |title=Technology Developments & Plant Efficiency for the Russian Nuclear Power Generation Market Wednesday |date=March 24, 2010}}</ref>

=== Fast reactors ===
A [[Fast-neutron reactor|fast reactor]] directly uses the fast neutrons emitted by fission, without moderation. Unlike thermal neutron reactors, fast neutron reactors can be configured to "'''burn'''", or fission, all [[actinides]], and given enough time, therefore drastically reduce the actinides fraction in [[spent nuclear fuel]] produced by the present world fleet of thermal neutron [[light water reactor]]s, thus closing the [[nuclear fuel cycle]]. Alternatively, if configured differently, they can also [[breeder reactor|'''breed''']] more actinide fuel than they consume.

==== Gas-cooled fast reactor (GFR) ====
[[File:Gas-Cooled Fast Reactor Schemata.svg|right|thumb|Gas-Cooled Fast Reactor (GFR)]]
{{Main article|Gas-cooled fast reactor}}
The '''gas-cooled fast reactor''' (GFR)<ref name="Roadmap"/> system features a fast-neutron spectrum and closed fuel cycle for efficient conversion of [[Fertile material|fertile uranium]] and management of actinides. The reactor is [[helium]]-cooled and with an outlet temperature of 850 °C it is an evolution of the [[very-high-temperature reactor]] (VHTR) to a more sustainable fuel cycle. It will use a direct [[Brayton cycle]] [[Closed-cycle gas turbine|gas turbine]] for high thermal efficiency. Several fuel forms are being considered for their potential to operate at very high temperatures and to ensure an excellent retention of [[Nuclear fission|fission]] products: composite [[ceramic]] fuel, advanced fuel particles, or ceramic clad elements of actinide compounds. Core configurations are being considered based on pin- or plate-based fuel assemblies or prismatic blocks.

The European Sustainable Nuclear Industrial Initiative is funding three Generation IV reactor systems, one of which is a gas-cooled fast reactor, called ''Allegro'', 100 MW(t), which will be built in a central or eastern European country with construction expected to begin in 2018.<ref name="euronuclear.org">{{cite web|url=https://www.euronuclear.org/1-information/news/Gen-IV.htm |title=The European Sustainable Nuclear Industrial Initiative (ESNII) will support three Generation IV reactor systems: a sodium-cooled fast reactor, or SFR, called ''Astrid'' that is proposed by France; a gas-cooled fast reactor, GFR, called ''Allegro'' supported by central and eastern Europe; and a lead-cooled fast reactor, LFR, technology pilot called ''Myrrha'' that is proposed by Belgium. |deadurl=yes |archiveurl=https://web.archive.org/web/20131009042600/http://euronuclear.org/1-information/news/Gen-IV.htm |archivedate=2013-10-09 |df= }}</ref> The central European [[Visegrád Group]] are committed to pursuing the technology.<ref>{{cite web |url=http://www.alphagalileo.org/ViewItem.aspx?ItemId=133111&CultureCode=en |title=The V4G4 Centre of Excellence for performing joint research, development and innovation in the field of Generation-4 (G4) nuclear reactors have been established. 20 July 2013 National Center for Nuclear Research (NCBJ)}}</ref> In 2013 German, British, and French institutes finished a 3-year collaboration study on the follow on industrial scale design, known as ''GoFastR''.<ref>{{cite web|url=http://www.ist-world.org/ProjectDetails.aspx?ProjectId=5cb8f3f283574cc6b2bdbf72533172d8 |title=the European Gas cooled Fast Reactor. |deadurl=yes |archiveurl=https://web.archive.org/web/20131213091046/http://www.ist-world.org/ProjectDetails.aspx?ProjectId=5cb8f3f283574cc6b2bdbf72533172d8 |archivedate=2013-12-13 |df= }}</ref> They were funded by the EU's 7th FWP [[framework programme]], with the goal of making a sustainable VHTR.<ref>{{cite web |url=http://www.2020-horizon.com/GOFASTR-European-Gas-Cooled-Fast-Reactor%28GOFASTR%29-s312.html |title=The GOFASTR research program}}</ref>

==== Sodium-cooled fast reactor (SFR) ====
[[File:Sodium-Cooled Fast Reactor Schemata.svg|right|thumb|Pool design Sodium-Cooled Fast Reactor (SFR)]]
{{Main article|Sodium-cooled fast reactor}}
{{see also|Prototype Fast Breeder Reactor|Experimental Breeder Reactor II|S-PRISM|BN-800 reactor|Toshiba 4S}}

In India, the [[Fast Breeder Test Reactor]] reached criticality in October 1985. In September 2002, fuel burn-up in the FBTR for the first time reached the 100,000 megawatt-days per metric ton uranium (MWd/MTU) mark. This is considered an important milestone in breeder reactor technology. Using the experience gained from the operation of the FBTR, the [[Prototype Fast Breeder Reactor]], a 500 MWe Sodium cooled fast reactor is being built at a cost of INR 5,677 crores (~US$900 million) and is expected to be critical by June 2018. The PFBR will be followed by six more Commercial Fast Breeder Reactors (CFBRs) of 600 MWe each.

The SFR<ref name="Roadmap"/> is a project that builds on two closely related existing projects, the liquid metal [[Breeder reactor#Fast breeder reactor|fast breeder reactor]] and the [[integral fast reactor]].

The goals are to increase the efficiency of uranium usage by [[breeder reactor|breeding]] plutonium and eliminating the need for [[transuranic]] isotopes ever to leave the site. The reactor design uses an unmoderated core running on [[fast neutron]]s, designed to allow any transuranic isotope to be consumed (and in some cases used as fuel). In addition to the benefits of removing the long [[half-life]] transuranics from the waste cycle, the SFR fuel expands when the reactor overheats, and the chain reaction automatically slows down. In this manner, it is passively safe.<ref>{{cite web |url=http://www.ne.anl.gov/About/hn/logos-winter02-psr.shtml|title=Passively safe reactors rely on nature to keep them cool|author=David Baurac}}</ref>

The SFR reactor concept is cooled by liquid [[sodium]] and fueled by a metallic alloy of uranium and [[plutonium]] or [[spent nuclear fuel]], the "nuclear waste" of [[light water reactor]]s. The SFR fuel is contained in steel cladding with liquid sodium filling in the space between the clad elements which make up the fuel assembly. One of the design challenges of an SFR is the risks of handling sodium, which reacts explosively if it comes into contact with water. However, the use of liquid metal instead of water as coolant allows the system to work at atmospheric pressure, reducing the risk of leakage.

The European Sustainable Nuclear Industrial Initiative is funding three Generation IV reactor systems, one of which is a sodium-cooled fast reactor, called ''[[ASTRID (reactor)|ASTRID]]'', Advanced Sodium Technical Reactor for Industrial Demonstration, [[Areva]], [[Commissariat à l'énergie atomique et aux énergies alternatives|CEA]] and [[Électricité de France|EDF]] are leading the design with British collaboration.<ref>{{cite web |url=http://www.power-eng.com/articles/2010/11/areva--cea-secure.html |title=Areva, CEA secure EUR650m funding to develop ASTRID sodium-cooled Generation IV reactor 11/11/2010}}</ref><ref>{{cite web |url=http://www.powermag.com/uk-and-france-sign-landmark-civil-nuclear-cooperation-agreement/ |title=UK and France Sign Landmark Civil Nuclear Cooperation Agreement 02/22/2012 . POWERnews}}</ref> Astrid will be rated about 600 MWe and is proposed to be built in France, near to the [[Phénix]] reactor. A final decision in construction is to be made in 2019<ref name="euronuclear.org"/>

The [[China|PRC]]'s first commercial-scale, 800 MWe, fast neutron reactor, to be situated near [[Sanming]] in [[Fujian province]] will be a SFR. In 2009 an agreement was signed that would entail the Russian [[BN-800 reactor]] design to be sold to the PRC once it is completed, this would be the first time commercial-scale fast neutron reactors have ever been exported.<ref>{{cite web |url=http://www.world-nuclear-news.org/C-Joint_venture_launched_for_Chinese_fast_reactor-3004104.html |title=Joint venture launched for Chinese fast reactor}}</ref> The BN-800 reactor became operational in 2014.

The 400 MWe [[Fast Flux Test Facility]] operated successfully for ten years at the Hanford site in Washington State.

The 20 MWe [[EBR II]] operated successfully for over thirty years at the Idaho National Laboratory, until it was shut down in 1994.

GE Hitachi's [[PRISM (reactor)|PRISM]] reactor is an SFR with the primary purpose of reducing the half lives of the fissionable elements present in used nuclear fuel while generating electricity largely as a by-product.

==== Lead-cooled fast reactor (LFR) ====
[[File:Lead-Cooled Fast Reactor Schemata.svg|right|thumb|Lead-Cooled Fast Reactor (LFR)]]
{{Main article|Lead-cooled fast reactor}}
{{See also|MYRRHA}}
The '''lead-cooled fast reactor'''<ref name="Roadmap">{{cite journal|year=2002 |title=A Technology Roadmap for Generation IV Nuclear Energy Systems |last=US DOE Nuclear Energy Research Advisory Committee |volume=GIF-002-00 |url=http://nuclear.energy.gov/genIV/documents/gen_iv_roadmap.pdf |deadurl=yes |archiveurl=https://web.archive.org/web/20071129121214/http://nuclear.energy.gov/genIV/documents/gen_iv_roadmap.pdf |archivedate=2007-11-29 |df= }}</ref> features a fast-neutron-spectrum [[lead]] or [[lead]]/[[bismuth]] [[eutectic]] ([[Lead-bismuth eutectic|LBE]]) liquid-metal-cooled reactor with a closed [[Nuclear fuel cycle|fuel cycle]]. Options include a range of plant ratings, including a "battery" of 50 to 150 MW of electricity that features a very long refueling interval, a modular system rated at 300 to 400 MW, and a large monolithic plant option at 1,200 MW (The term ''battery'' refers to the long-life, factory-fabricated core, not to any provision for electrochemical energy conversion). The fuel is metal or nitride-based containing [[Fertile material|fertile uranium]] and [[transuranic]]s. The LFR is cooled by natural [[convection]] with a reactor outlet coolant temperature of 550 °C, possibly ranging up to 800 °C with advanced materials. The higher temperature enables the production of [[Thermochemical cycle|hydrogen by thermochemical processes]].

The European Sustainable Nuclear Industrial Initiative is funding three Generation IV reactor systems, one of which is a lead-cooled fast reactor that is also an [[Subcritical reactor|accelerator-driven sub-critical]] reactor, called ''[[MYRRHA]]'', 100 MW(t), which will be built in [[Belgium]] with construction expected to begin after 2014 and the industrial scale version, known as ''Alfred'', slated to be constructed sometime after 2017. A reduced-power model of Myrrha called ''Guinevere'' was started up at [[Mol, Belgium|Mol]] in March 2009.<ref name="euronuclear.org"/> In 2012 the research team reported that Guinevere was operational.<ref>{{cite news|last1=Hellemans|first1=Alexander|title=Reactor-Accelerator Hybrid Achieves Successful Test Run|url=http://news.sciencemag.org/physics/2012/01/reactor-accelerator-hybrid-achieves-successful-test-run|accessdate=29 December 2014|work=Science Insider|date=12 January 2012}}</ref>

Two other lead-cooled fast reactors under development are the SVBR-100, a modular 100 MWe lead-bismuth cooled fast neutron reactor concept designed by OKB [[Gidropress]] in Russia and the [[BREST (Reactor)|BREST-OD-300]] (Lead-cooled fast reactor) 300 MWe, to be developed after the SVBR-100, and built over 2016-20, it will dispense with the [[Uranium-238|fertile blanket]] around the core and will supersede the sodium cooled [[BN-600 reactor]] design, to purportedly give enhanced proliferation resistance.<ref name="powertecrussia.com"/>

== Advantages and disadvantages ==
Relative to current nuclear power plant technology, the claimed benefits for 4th generation reactors include:
* Nuclear waste that remains radioactive for a few centuries instead of millennia<ref>{{cite web |title=Strategies to Address Global Warming |url=http://www.columbia.edu/~jeh1/mailings/2009/20090713_Strategies.pdf}}</ref>
* 100–300 times more energy yield from the same amount of nuclear fuel<ref>{{cite web |title=4th Generation Nuclear Power |url=http://www.ossfoundation.us/projects/energy/nuclear}}</ref>
* Broader range of fuels, and even unencapsulated raw fuels (non-pebble [[Molten Salt Reactor|MSR]], [[Liquid fluoride thorium reactor|LFTR]]).
* In some reactors, the ability to consume existing nuclear waste in the production of electricity, that is, a Closed [[nuclear fuel cycle]]. This strengthens the argument to deem [[nuclear power as renewable energy]].
* Improved operating safety features, such as (depending on design) avoidance of pressurized operation, automatic passive (unpowered, uncommanded) reactor shutdown, avoidance of water cooling and the associated risks of loss of water (leaks or boiling) and hydrogen generation/explosion and contamination of coolant water.

Nuclear reactors do not emit CO2 during operation, although like all [[low carbon power]] sources, the mining and construction phase can result in CO2 emissions, if energy sources which are not carbon neutral (such as fossil fuels), or CO2 emitting cements are used during the construction process.
A 2012 [[Yale University]] review published in the Journal of Industrial Ecology analyzing {{CO2}} [[life cycle assessment]] (LCA) emissions from [[nuclear power]] determined that:<ref name="Warner + Heath, JoIE">Warner, Ethan S.; Heath, Garvin A. [http://onlinelibrary.wiley.com/doi/10.1111/j.1530-9290.2012.00472.x/full Life Cycle Greenhouse Gas Emissions of Nuclear Electricity Generation: Systematic Review and Harmonization], ''Journal of Industrial Ecology'', [[Yale University]], published online April 17, 2012, {{doi|10.1111/j.1530-9290.2012.00472.x}}</ref>
{{Quote|The collective LCA literature indicates that life cycle [[Greenhouse gas|GHG]] [greenhouse gas] emissions from nuclear power are only a fraction of traditional fossil sources and comparable to renewable technologies.}}
Although the paper primarily dealt with data from [[Generation II reactor]]s, and did not analyze the {{CO2}} emissions by 2050 of the presently under construction [[Generation III reactor]]s, it did summarize the Life Cycle Assessment findings of in development reactor technologies.{{Quote|FBRs ['[[Fast Breeder Reactor]]s'] have been evaluated in the LCA literature. The limited literature that evaluates this potential future technology reports [[median]] life cycle GHG emissions... similar to or lower than LWRs [Gen II [[light water reactor]]s] and purports to consume little or no [[uranium market|uranium ore]].}}

A specific risk of the sodium-cooled fast reactor is related to using metallic sodium as a coolant. In case of a breach, sodium explosively reacts with water. Fixing breaches may also prove dangerous, as the cheapest noble gas [[argon]] is also used to prevent sodium oxidation. Argon, like helium, can displace oxygen in the air and can pose [[hypoxia (environmental)|hypoxia]] concerns, so workers may be exposed to this additional risk. This is a pertinent problem as demonstrated by the events at the [[LMFBR|loop type]] [[Monju Nuclear Power Plant|Prototype Fast Breeder Reactor Monju]] at Tsuruga, Japan.<ref>{{cite news |title=Japan Strains to Fix a Reactor Damaged Before Quake |url=https://www.nytimes.com/2011/06/18/world/asia/18japan.html | work=The New York Times | first=Hiroko |last=Tabuchi |date=17 June 2011}}</ref>
Using lead or molten salts mitigates this problem by making the coolant less reactive and allowing a high freezing temperature and low pressure in case of a leak. Disadvantages of lead compared to sodium are much higher viscosity, much higher density, lower heat capacity, and more radioactive neutron activation products.

In many cases, there is already a large amount of experience built up with numerous proof of concept Gen IV designs. For example, the reactors at [[Fort St. Vrain Generating Station]] and [[HTR-10]] are similar to the proposed Gen IV [[VHTR]] designs, and the [[LMFBR|pool type]] [[EBR-II]], [[Phénix]] and [[BN-600]] reactor are similar to the proposed pool type Gen IV Sodium Cooled Fast reactors being designed.

== Table of designs ==

{| class=wikitable
|+ Summary of designs for generation IV reactors<ref>https://www.gen-4.org/gif/upload/docs/application/pdf/2013-09/gif_rd_outlook_for_generation_iv_nuclear_energy_systems.pdf</ref>
|-
! System
! Neutron Spectrum
! Coolant
! Temperature (°C)
! Fuel Cycle
! Size (MW)
!Example developers
|-
| [[Very-high-temperature reactor|VHTR]]
| Thermal
| Helium
| 900–1000
| Open
| 250–300
|[[Japan Atomic Energy Agency|JAEA]] ([[High-temperature engineering test reactor|HTTR]]), [[Tsinghua University]] ([[HTR-10]]), [[X-energy]]<ref name="energy.gov">{{cite web|title=Energy Department Announces New Investments in Advanced Nuclear Power Reactors...|url=https://www.energy.gov/articles/energy-department-announces-new-investments-advanced-nuclear-power-reactors-help-meet|website=[[United States Department of Energy|US Department of Energy]]|accessdate=16 January 2016}}</ref>
|-
| [[Sodium-cooled fast reactor|SFR]]
| Fast
| Sodium
| 550
| Closed
| 30–150, 300–1500, 1000–2000
|[[TerraPower]] ([[Traveling wave reactor|TWR]]), [[Toshiba]] ([[Toshiba 4S|4S]]), [[GE Hitachi Nuclear Energy]] ([[PRISM (reactor)|PRISM]])
|-
| [[Supercritical water reactor|SCWR]]
| Thermal or fast
| Water
| 510–625
| Open or closed
| 300–700, 1000–1500
|
|-
| [[Gas-cooled fast reactor|GFR]]
| Fast
| Helium
| 850
| Closed
| 1200
|[[Energy Multiplier Module]]
|-
| [[Lead-cooled fast reactor|LFR]]
| Fast
| Lead
| 480–800
| Closed
| 20–180, 300–1200, 600–1000
|
|-
| [[Molten salt reactor|MSR]]
| Fast or thermal
| Fluoride or chloride salts
| 700–800
| Closed
| 250, 1000
|[[Seaborg Technologies]], [[TerraPower]], [[Stable Salt Reactor|Moltex Energy]], [[Flibe Energy]] ([[Liquid fluoride thorium reactor|LFTR]]), [[Transatomic Power]], Thorium Tech Solution ([[Fuji Molten Salt Reactor|FUJI MSR]]), Terrestrial Energy ([[IMSR]]), [[Southern Company Services|Southern Company]]<ref name="energy.gov"/>, [[Elysium Industries]]<ref>http://www.elysiumindustries.com/</ref>
|-
| [[Dual fluid reactor|DFR]]
| Fast
| Lead
| 1000
| Closed
| 500–1500
| Institute for Solid-State Nuclear Physics<ref name=ifk>{{cite web |url=https://festkoerper-kernphysik.de/dfr.pdf |title=Dual Fluid Reactor - IFK |date=2013-06-16 |website=festkoerper-kernphysik.de |publisher= Institut für Festkörper-Kernphysik |format=PDF |location=Berlin, Germany |access-date=2017-08-28}}</ref>, [[Aristos Power]] <ref name=HSR>{{|url=http://aristospower.tk |title=Hard Spectrum Reactor - HSR</ref>
|}

== See also ==
{{portal|Energy|Nuclear technology}}
{{colbegin}}
* [[Nuclear reactor]]
* [[Nuclear material]]
* [[Nuclear physics]]
* [[List of reactor types#Reactor types|List of reactor types]]
* [[Generation II reactor]]
* [[Generation III reactor]]
* [[Integral Fast Reactor]]
* [[Liquid fluoride thorium reactor]]
* [[Breeder reactor]]
* [[Small modular reactor]]
{{colend}}

==References==
{{Reflist|30em}}

== External links ==
* [https://inlportal.inl.gov/portal/server.pt?open=514&objID=1361&parentname=CommunityPage&parentid=10&mode=2&in_hi_userid=200&cached=true Article from Idaho National Laboratory detailing some current efforts at developing Gen. IV reactors.]
* [http://www.gen-4.org/ Generation IV International Forum (GIF)]
* [https://web.archive.org/web/20070205115654/http://nuclear.energy.gov/genIV/neGenIV1.html U.S. Department of Energy Office of Nuclear Energy, Science and Technology]
* [https://web.archive.org/web/20060512033030/http://www.engr.utk.edu/nuclear/colloquia/slides/Gen%20IV%20U-Tenn%20Presentation.pdf Gen IV presentation]
* [http://www.ecology.at/ecology/files/pr577_1.pdf Science or Fiction - Is there a Future for Nuclear?] (Nov. 2007) - A publication from the Austrian [[Ecology Institute (Austria)|Ecology Institute]] about 'Generation IV' and Fusion reactors.
* {{cite web |url=http://memagazine.asme.org/Articles/2011/December/Nuclear_Power_After_Fukushima.cfm |title=Nuclear Power After Fukushima |author=Gail H. Marcus |date=December 2011 |work=Mechanical Engineering (the magazine of [[ASME]]) |accessdate=23 January 2012}} "In the wake of a severe plant accident, advanced reactor designs are getting renewed attention."
* [http://www.itheo.org/ International Thorium Energy Organisation - www.IThEO.org]
* [http://www.ithec.org/ International Thorium Energy Committee - iThEC]

{{Nuclear fission reactors}}

[[Category:Nuclear power reactor types]]
[[Category:Idaho National Laboratory]]

Merchants of Doubt

2017-12-11T15:42:47Z

Boundarylayer: /* Counterargument */

{{About|the book|the film based on the book|Merchants of Doubt (film)}}
{{Use mdy dates|date=December 2015}}
{{good article}}
{{Infobox book
| name = Merchants of Doubt: How a Handful of Scientists Obscured the Truth on Issues from Tobacco Smoke to Global Warming
| image = Merchants of DOUBT.jpg
| image_size = 197px
| caption =
| author = [[Naomi Oreskes]], [[Erik M. Conway]]
| illustrator =
| cover_artist =
| country =
| series =
| subject = Scientists—Professional Ethics Science news—Moral and ethical aspects
| published = June 3, 2010 [[Bloomsbury Press]]
| media_type =
| pages = 355 pp.
| isbn = 978-1-59691-610-4
| oclc = 461631066
| dewey = 174.95
| congress = Q147 .O74 2010
}}

'''''Merchants of Doubt: How a Handful of Scientists Obscured the Truth on Issues from Tobacco Smoke to Global Warming''''' is a 2010 non-fiction book by American [[History of science|historians of science]] [[Naomi Oreskes]] and [[Erik M. Conway]]. It identifies parallels between the [[global warming controversy]] and earlier controversies over [[tobacco smoking]], [[acid rain]], [[DDT]], and the [[ozone depletion|hole in the ozone layer]]. Oreskes and Conway write that in each case "keeping the controversy alive" by spreading doubt and confusion after a scientific consensus had been reached, was the basic strategy of those opposing action.<ref name = stek>{{cite news |author=Steketee, Mike |title=Some sceptics make it a habit to be wrong |url=http://www.theaustralian.com.au/national-affairs/some-sceptics-make-it-a-habit-to-be-wrong/story-fn59niix-1225956414538 |newspaper=[[The Australian]] |date=November 20, 2010 }}</ref> In particular, they say that [[Fred Seitz]], [[Fred Singer]], and a few other [[contrarian]] scientists joined forces with conservative [[think tank]]s and private corporations to challenge the scientific consensus on many contemporary issues.<ref>{{cite book |first1=Naomi |last1=Oreskes |first2=Erik M. |last2=Conway |title=Merchants of Doubt: How a Handful of Scientists Obscured the Truth on Issues from Tobacco Smoke to Global Warming |url=https://books.google.com/books?id=fpMh3nh3JI0C&pg=PP4 |year=2010 |publisher=Bloomsbury Press |isbn=978-1-59691-610-4 |page=6 |ref=harv}} [http://www.merchantsofdoubt.org/index.html merchantsofdoubt.org]</ref>

The [[George C. Marshall Institute]] and Fred Singer, two of the subjects, have been critical of the book. Other reviewers have been more favorable. One reviewer said that ''Merchants of Doubt'' is exhaustively researched and documented, and may be one of the most important books of 2010. Another reviewer saw the book as his choice for best [[science book]] of the year.<ref name=Mckie8/> It was made into a film, ''[[Merchants of Doubt (film)|Merchants of Doubt]]'', directed by [[Robert Kenner]], released in 2014.<ref>{{cite web | url=http://sonyclassics.com/merchantsofdoubt/ | title=Merchants of Doubt | publisher=Sony Pictures Classics | accessdate=March 8, 2015}}</ref>

==Themes==
[[File:S Fred Singer 2011.jpg |thumb|right |[[Fred Singer]] (2011), a prominent opponent of greenhouse gas regulation.]]
Oreskes and Conway write that a handful of [[Conservatism in the United States|politically conservative]] scientists, with strong ties to particular industries, have "played a disproportionate role in debates about controversial questions".<ref name=pk/> The authors write that this has resulted in "deliberate obfuscation" of the issues which has had an influence on [[Public opinion on climate change|public opinion]] and [[Climate change policy of the United States|policy-making]].<ref name=pk>{{cite journal |author=Kitcher, Philip |authorlink=Philip Kitcher |title=The Climate Change Debates |journal=[[Science (journal)|Science]] |volume=328 |issue=5983 |pages=1231–2 |date=June 4, 2010 |doi=10.1126/science.1189312 |url=http://www.sciencemag.org/cgi/content/full/328/5983/1230-a }}</ref>

The book criticizes the so-called Merchants of Doubt, some predominantly American science key players, above all [[William Nierenberg|Bill Nierenberg]], [[Fred Seitz]], and [[Fred Singer]]. All three are physicists: Singer was a [[rocket scientist]], whereas Nierenberg and Seitz worked on the atomic bomb.<ref name=sb>{{cite news |author=Brown, Seth |title='Merchants of Doubt' delves into contrarian scientists |url=https://www.usatoday.com/money/books/reviews/2010-06-01-deathmerchants01_ST_N.htm |newspaper=[[USA Today]] |date=May 31, 2010 }}</ref> They have been active on topics like acid rain, tobacco smoking, global warming and pesticides. The book claims that these scientists have challenged and diluted the [[scientific consensus]] in the various fields, as of the [[dangers of smoking]], the effects of acid rain, the existence of the ozone hole, and the existence of [[anthropogenic climate change]].<ref name=pk/> Seitz and Singer have been involved with institutions such as [[The Heritage Foundation]], [[Competitive Enterprise Institute]] and [[George C. Marshall Institute]] in the United States. Funded by [[corporation]]s and conservative [[Foundation (United States law)|foundations]], these organizations have opposed many forms of [[Economic interventionism|state intervention]] or regulation of U.S. citizens. The book lists similar tactics in each case: "discredit the science, disseminate false information, spread confusion, and promote doubt".<ref name=rm/>

The book states that Seitz, Singer, Nierenberg and [[Robert Jastrow]] were all fiercely [[Anti-communism|anti-communist]] and they viewed government regulation as a step towards [[socialism]] and [[communism]]. The authors argue that, with the [[collapse of the Soviet Union]], they looked for another great threat to free market capitalism and found it in environmentalism. They feared that an over-reaction to environmental problems would lead to heavy-handed government intervention in the marketplace and intrusion into people's lives.<ref name=ocmerch/> Oreskes and Conway state that the longer the delay the worse these problems get, and the more likely it is that governments will need to take the draconian measures that conservatives and [[market fundamentalism|market fundamentalists]] most fear. They say that Seitz, Singer, Nierenberg and Jastrow denied the scientific evidence, contributed to a strategy of delay, and thereby helped to bring about the situation they most dreaded.<ref name=ocmerch>{{harvnb|Oreskes|Conway|2010|pp=248–255}}</ref> The authors have a strong doubt about the ability of the media to differentiate between false truth and the actual science in question; however, they stop short of endorsing censorship in the name of science.<ref name ="RG" /> The journalistic norm of balanced reporting has helped, according to the authors, to amplify the misleading messages of the contrarians. Oreskes and Conway state: "small numbers of people can have large, negative impacts, especially if they are organised, determined and have access to power".<ref name=rm>{{cite news |author=McKie, Robin |title=A dark ideology is driving those who deny climate change |url=https://www.theguardian.com/commentisfree/2010/aug/01/climate-change-robin-mckie |newspaper=The Guardian |date=August 1, 2010 }}</ref>

The main conclusion of the book is that there would have been more progress in policymaking, if not for the influence of the contrarian "experts", which tried on ideological reasons to undermine trust in the science base for regulation.<ref name="RG">{{cite journal|last1=Grundmann|first1=Reiner|title=Debunking sceptical propaganda|journal=BioSocieties|date=29 August 2013|volume=8|issue=3|pages=370–374|doi=10.1057/biosoc.2013.15|url=https://www.academia.edu/4754580/Debunking_skeptical_propaganda_Book_review_of_Oreskes_Conway_Merchants_of_Doubt}}</ref> Similar conclusions were already drawn, among others on [[Frederick Seitz]] and [[William Nierenberg]] in the book ''[[Requiem for a Species|Requiem for a Species: Why We Resist the Truth about Climate Change]]'' (2010) by Australian academic [[Clive Hamilton]].

==Reception==

[[Philip Kitcher]] in ''[[Science (magazine)|Science]]'' says that Naomi Oreskes and Erik Conway are "two outstanding historians".<ref name=pk/> He calls ''Merchants of Doubt'' a "fascinating and important study". Kitcher says that the apparently harsh claims against Nierenberg, Seitz, and Singer are "justified through a powerful dissection of the ways in which prominent climate scientists, such as [[Roger Revelle]] and [[Ben Santer]], were exploited or viciously attacked in the press".<ref name=pk/>

In ''[[The Christian Science Monitor]]'', Will Buchanan says that ''Merchants of Doubt'' is exhaustively researched and documented, and may be one of the most important books of 2010. Oreskes and Conway are seen to demonstrate that the doubt merchants are not "objective scientists" as the term is popularly understood. Instead, they are "science-speaking mercenaries" hired by corporations to process numbers to prove that the corporations’ products are safe and useful. Buchanan says they are salesmen, not scientists.<ref>Buchanan, Will (June 22, 2010). [http://www.csmonitor.com/Books/Book-Reviews/2010/0622/Merchants-of-Doubt Merchants of Doubt: How “scientific” misinformation campaigns sold untruths to consumers] ''The Christian Science Monitor''.</ref>

Bud Ward published a review of the book in ''The Yale Forum on Climate and the Media''. He wrote that Oreskes and Conway use a combination of thorough scholarly research combined with writing reminiscent of the best investigative journalism, to "unravel deep common links to past environmental and public health controversies".<ref name="Ward">Ward, Bud (July 8, 2010). [http://www.yaleclimatemediaforum.org/2010/07/merchants-of-doubt/ Reviews: Leaving No Doubt on Tobacco, Acid Rain, Climate Change], ''The Yale Forum on Climate and the Media''.</ref> In terms of climate science, the authors' leave "little doubt about their disdain for what they regard as the misuse and abuse of science by a small cabal of scientists they see as largely lacking in requisite climate science expertise".<ref name="Ward" />

Phil England writes in ''[[The Ecologist]]'' that the strength of the book is the rigour of the research and the detailed focus on key incidents. He said, however, that the climate change chapter is only 50 pages long, and recommends several other books for readers who want to get a broader picture of this aspect: [[Jim Hoggan]]’s ''Climate Cover-Up'', [[George Monbiot]]’s ''Heat: How to Stop the Planet Burning'' and [[Ross Gelbspan]]’s ''The Heat is On'' and ''Boiling Point''. England also said that there is little coverage about the millions of dollars which [[Exxon Mobil]] has put into funding groups actively involved in promoting [[climate change denial]] and doubt.<ref>England, Phil (September 10, 2010). [http://www.theecologist.org/reviews/books/592288/merchants_of_doubt.html Merchants of Doubt] ''[[The Ecologist]]''.</ref>

A review in ''[[The Economist]]'' calls this a powerful book which articulates the politics involved and the degree to which scientists have sometimes manufactured and exaggerated environmental uncertainties, but opines that the authors fail to fully explain how environmental action has still often proved possible despite countervailing factors.<ref>[http://www.economist.com/node/16374460 All guns blazing: A question of dodgy science], (June 17, 2010), ''[[The Economist]]''.</ref>

A review in ''[[Psychology Today]]'' drew parallels with the book and the contested medical claims and subsequent legal battle as depicted in the film [[Erin Brockovich (film)|Erin Brockovich (2000)]].<ref>[https://www.psychologytoday.com/blog/side-effects/201107/merchants-doubt Merchants of Doubt On Manufactured Controversy and Dissent in Science. Posted Jul 04, 2011]</ref> Naomi Oreske, has compared herself to [[Erin Brockovich]], describing what served as the motivated for writing the book, her "Erin Brockovich moment".<ref>[http://gelbspanfiles.com/?p=4195 To be Credible, you must Keep Your Story Straight, Pt 2: “Oreskes’ timeline problem”]</ref><ref>[http://culturesofenergy.com/ep-47-naomi-oreskes/ Ms Oreskes December 2016 Rice University CENHS podcast interview. c. 44:40]</ref>

[[Robert N. Proctor]], who coined the term "[[agnotology]]" to describe the study of culturally induced ignorance or doubt, wrote in ''[[American Scientist]]'' that ''Merchants of Doubt'' is a detailed and artfully written book. He set it in the context of other books which cover the "history of manufactured ignorance":<ref name="Proctor">Proctor, Robert (September–October 2010). [http://www.americanscientist.org/bookshelf/pub/manufactured-ignorance Book Review: Manufactured Ignorance], ''[[American Scientist]]''.</ref> [[David Michaels (epidemiologist)|David Michaels]]’s ''[[Doubt is their Product]]'' (2008), [[Chris Mooney (journalist)|Chris Mooney]]’s ''[[The Republican War on Science]]'' (2009), [[David Rosner]] and Gerald Markowitz’s ''[[Deceit and Denial]]'' (2002), and his own book ''[[Cancer Wars]]'' (1995).<ref name="Proctor" />

Robin McKie in ''[[The Guardian]]'' states that Oreskes and Conway deserve considerable praise for exposing the influence of a small group of [[Cold War]] ideologues. Their tactic of spreading doubt has confused the public about a series of key scientific issues such as global warming, even though scientists have actually become more certain about their research results. McKie says that ''Merchants of Doubt'' includes detailed notes on all sources used, is carefully paced, and is "my runaway contender for best science book of the year".<ref name=Mckie8>McKie, Robin (August 8, 2010). [https://www.theguardian.com/books/2010/aug/08/merchants-of-doubt-oreskes-conway "Merchants of Doubt by Naomi Oreskes and Erik M Conway".] ''The Guardian''.</ref>

Sociologist [[Reiner Grundmann]]'s review in ''[[BioSocieties]]'' journal, acknowledges that the book is well researched and factually based, but criticizes the book as being written in a black and white manner whereas historians should write a more nuanced description. The book depicts special interests and contrarians misleading the public as being mainly responsible for stopping action on policy. He says this shows a lack of basic understanding of the political process and the mechanisms of [[knowledge policy]], because the authors assume that public policy would follow on from an understanding of the science. While the book provides ''all the (formal) hallmarks of science'', Grundmann sees it less as a scholarly work than a passionate attack and overall as a problematic book.<ref name="RG" />

William O’Keefe and Jeff Kueter from the [[George C. Marshall Institute]], which was founded by Seitz,<ref>{{cite web|last1=Begley|first1=Sharon|title=Global Warming Deniers: A Well-Funded Machine|url=http://www.newsweek.com/global-warming-deniers-well-funded-machine-99295|website=Newsweek|date=4 August 2007|quote=...a central cog in the denial machine: the George C. Marshall Institute, a conservative think tank.}}</ref> say that although ''Merchants of Doubt'' has the appearance of a scholarly work, it discredits and undermines the reputations of people who in their lifetime contributed greatly to the American nation. They say that it does this by questioning their integrity, impugning their character, and questioning their judgement.<ref>{{cite web | last=O’Keefe | first= William |last2= Kueter| first2=Jeff | date=June 2010 | url=http://marshall.org/wp-content/uploads/2011/06/OKeefe-and-Kueter-Clouding-the-Truth-A-Critique-of-Merchants-of-Doubt.pdf |title=Clouding the Truth: A Critique of Merchants of Doubt |publisher=[[George C. Marshall Institute]] |work=Policy Outlook | quote=Although cloaked in the appearance of scholarly work, the book constitutes an effort to discredit and undermine the reputations of three deceased scientists who contributed greatly to our nation... This book questions their integrity, impugns their character, and questions their judgment on the basis of little more than faulty logic and preconceived opinion}}</ref>

==Authors==
[[File:Naomi Oreskes 2nd European TA conference in Berlin 2015 (cropped to collar).JPG |thumb|right |[[Naomi Oreskes]] (2015), co-author of ''Merchants of Doubt''.]]
Naomi Oreskes is Professor of History and Science Studies at Harvard University. She has degrees in geological science and a [[Doctor of Philosophy|Ph.D.]] in [[Geological]] Research and the History of Science. Her work came to public attention in 2004 with the publication of "The Scientific Consensus on Climate Change," in ''Science'', in which she wrote that there was no significant disagreement in the scientific community about the reality of global warming from human causes.<ref name=collins>[http://www.marcovigevani.com/upload/london_2008/Collins_Literary_London_2008_Rights_List.pdf Collins Literary Agency Rights Guide/March 2008]</ref> Erik M. Conway is the historian at [[NASA]]'s [[Jet Propulsion Laboratory]] at the [[California Institute of Technology]] in [[Pasadena, California|Pasadena]].<ref name=collins/>

==Counterargument==
In 2011, aerospace engineer [[Robert Zubrin]], most famous for penning ''[[The Case for Mars]]'', published a book length response a year after ''Merchants of Doubt'', titled ''Merchants of Despair: Radical Environmentalists, Criminal Pseudo-Scientists, and the Fatal Cult of Antihumanism'', the book traces the history of [[antihumanism]] over the last two centuries, from [[Thomas Malthus]] and the [[eugenics]] movement through to the [[Anti-nuclear movement|anti-nuclear]] and "alarmist" DDT and [[Global warming controversy|global warming]] campaigns. Zubrin argues that these movements, by means of pseudo-science and other methods, have used an appeal to environmentalism that is frequently based on statistical mis-treatments and personal ancedotes, rather than hard science, to mask actions that have and will continue to result in human suffering and deaths, with a number of activists within these groups all having attempted to gain oppressive political control through the restriction of human activities and freedom.<ref>[https://www.forbes.com/sites/larrybell/2013/07/31/racism-and-genocide-cloaked-in-green-camouflage/#3bb2eda517aa Books: Robert Zubrin's Merchants Of Despair Reveals Racism And Genocide Cloaked In Green Camouflage]</ref><ref>[https://www.theobjectivestandard.com/issues/2012-fall/review-merchants-of-despair/
Review: Merchants of Despair, by Robert Zubrin. Ted Gray February 2, 2014 In ''The Objective Standard'' Fall 2012]</ref>

==See also==
* [[Climate change controversy]]
* [[Climate change policy of the United States]]
* ''[[Climate Capitalism]]''
* [[Fear, uncertainty and doubt]]
* [[Greenhouse Mafia]]
* [[Health effects of tobacco]]
* [[List of books about the politics of science]]
* [[List of scientists opposing the mainstream scientific assessment of global warming]] in contrast with [[Scientific opinion on climate change]]
* [[Media coverage of climate change]]
* [[Scientific consensus]]
* [[Tobacco control movement]]
* [[Tobacco politics]]

=== Other books on the same theme ===
* ''[[Doubt Is Their Product: How Industry's Assault on Science Threatens Your Health]]'' (2008) by [[David Michaels (epidemiologist)|David Michaels]]
* ''Climate Cover-Up: The Crusade to Deny Global Warming'' (2009) by James Hoggan and Richard Littlemore
* ''[[Climate Change Denial: Heads in the Sand]]'' (2011) by Haydn Washington and John Cook

==References==
{{Reflist|30em}}

==External links==
* {{official website|http://www.merchantsofdoubt.org/index.html}}
* [http://www.abc.net.au/rn/scienceshow/stories/2011/3101369.htm Merchants of Doubt], Public Lecture (2010), [[University of NSW]], ''The Science Show'', [[ABC Radio National]], January 8, 2011.

{{Portal bar|Global warming|Environment}}

[[Category:2010 books]]
[[Category:2010 in the environment]]
[[Category:21st-century history books]]
[[Category:History books about science]]
[[Category:History books about politics]]
[[Category:Climate change books]]
[[Category:Climate change skepticism and denial]]
[[Category:Environmental non-fiction books]]
[[Category:Political books]]
[[Category:Books about the politics of science]]
[[Category:Books adapted into films]]
[[Category:Professional ethics]]
[[Category:Doubt]]

Merchants of Doubt

2017-12-11T13:30:14Z

Boundarylayer: /* Reception */

{{About|the book|the film based on the book|Merchants of Doubt (film)}}
{{Use mdy dates|date=December 2015}}
{{good article}}
{{Infobox book
| name = Merchants of Doubt: How a Handful of Scientists Obscured the Truth on Issues from Tobacco Smoke to Global Warming
| image = Merchants of DOUBT.jpg
| image_size = 197px
| caption =
| author = [[Naomi Oreskes]], [[Erik M. Conway]]
| illustrator =
| cover_artist =
| country =
| series =
| subject = Scientists—Professional Ethics Science news—Moral and ethical aspects
| published = June 3, 2010 [[Bloomsbury Press]]
| media_type =
| pages = 355 pp.
| isbn = 978-1-59691-610-4
| oclc = 461631066
| dewey = 174.95
| congress = Q147 .O74 2010
}}

'''''Merchants of Doubt: How a Handful of Scientists Obscured the Truth on Issues from Tobacco Smoke to Global Warming''''' is a 2010 non-fiction book by American [[History of science|historians of science]] [[Naomi Oreskes]] and [[Erik M. Conway]]. It identifies parallels between the [[global warming controversy]] and earlier controversies over [[tobacco smoking]], [[acid rain]], [[DDT]], and the [[ozone depletion|hole in the ozone layer]]. Oreskes and Conway write that in each case "keeping the controversy alive" by spreading doubt and confusion after a scientific consensus had been reached, was the basic strategy of those opposing action.<ref name = stek>{{cite news |author=Steketee, Mike |title=Some sceptics make it a habit to be wrong |url=http://www.theaustralian.com.au/national-affairs/some-sceptics-make-it-a-habit-to-be-wrong/story-fn59niix-1225956414538 |newspaper=[[The Australian]] |date=November 20, 2010 }}</ref> In particular, they say that [[Fred Seitz]], [[Fred Singer]], and a few other [[contrarian]] scientists joined forces with conservative [[think tank]]s and private corporations to challenge the scientific consensus on many contemporary issues.<ref>{{cite book |first1=Naomi |last1=Oreskes |first2=Erik M. |last2=Conway |title=Merchants of Doubt: How a Handful of Scientists Obscured the Truth on Issues from Tobacco Smoke to Global Warming |url=https://books.google.com/books?id=fpMh3nh3JI0C&pg=PP4 |year=2010 |publisher=Bloomsbury Press |isbn=978-1-59691-610-4 |page=6 |ref=harv}} [http://www.merchantsofdoubt.org/index.html merchantsofdoubt.org]</ref>

The [[George C. Marshall Institute]] and Fred Singer, two of the subjects, have been critical of the book. Other reviewers have been more favorable. One reviewer said that ''Merchants of Doubt'' is exhaustively researched and documented, and may be one of the most important books of 2010. Another reviewer saw the book as his choice for best [[science book]] of the year.<ref name=Mckie8/> It was made into a film, ''[[Merchants of Doubt (film)|Merchants of Doubt]]'', directed by [[Robert Kenner]], released in 2014.<ref>{{cite web | url=http://sonyclassics.com/merchantsofdoubt/ | title=Merchants of Doubt | publisher=Sony Pictures Classics | accessdate=March 8, 2015}}</ref>

==Themes==
[[File:S Fred Singer 2011.jpg |thumb|right |[[Fred Singer]] (2011), a prominent opponent of greenhouse gas regulation.]]
Oreskes and Conway write that a handful of [[Conservatism in the United States|politically conservative]] scientists, with strong ties to particular industries, have "played a disproportionate role in debates about controversial questions".<ref name=pk/> The authors write that this has resulted in "deliberate obfuscation" of the issues which has had an influence on [[Public opinion on climate change|public opinion]] and [[Climate change policy of the United States|policy-making]].<ref name=pk>{{cite journal |author=Kitcher, Philip |authorlink=Philip Kitcher |title=The Climate Change Debates |journal=[[Science (journal)|Science]] |volume=328 |issue=5983 |pages=1231–2 |date=June 4, 2010 |doi=10.1126/science.1189312 |url=http://www.sciencemag.org/cgi/content/full/328/5983/1230-a }}</ref>

The book criticizes the so-called Merchants of Doubt, some predominantly American science key players, above all [[William Nierenberg|Bill Nierenberg]], [[Fred Seitz]], and [[Fred Singer]]. All three are physicists: Singer was a [[rocket scientist]], whereas Nierenberg and Seitz worked on the atomic bomb.<ref name=sb>{{cite news |author=Brown, Seth |title='Merchants of Doubt' delves into contrarian scientists |url=https://www.usatoday.com/money/books/reviews/2010-06-01-deathmerchants01_ST_N.htm |newspaper=[[USA Today]] |date=May 31, 2010 }}</ref> They have been active on topics like acid rain, tobacco smoking, global warming and pesticides. The book claims that these scientists have challenged and diluted the [[scientific consensus]] in the various fields, as of the [[dangers of smoking]], the effects of acid rain, the existence of the ozone hole, and the existence of [[anthropogenic climate change]].<ref name=pk/> Seitz and Singer have been involved with institutions such as [[The Heritage Foundation]], [[Competitive Enterprise Institute]] and [[George C. Marshall Institute]] in the United States. Funded by [[corporation]]s and conservative [[Foundation (United States law)|foundations]], these organizations have opposed many forms of [[Economic interventionism|state intervention]] or regulation of U.S. citizens. The book lists similar tactics in each case: "discredit the science, disseminate false information, spread confusion, and promote doubt".<ref name=rm/>

The book states that Seitz, Singer, Nierenberg and [[Robert Jastrow]] were all fiercely [[Anti-communism|anti-communist]] and they viewed government regulation as a step towards [[socialism]] and [[communism]]. The authors argue that, with the [[collapse of the Soviet Union]], they looked for another great threat to free market capitalism and found it in environmentalism. They feared that an over-reaction to environmental problems would lead to heavy-handed government intervention in the marketplace and intrusion into people's lives.<ref name=ocmerch/> Oreskes and Conway state that the longer the delay the worse these problems get, and the more likely it is that governments will need to take the draconian measures that conservatives and [[market fundamentalism|market fundamentalists]] most fear. They say that Seitz, Singer, Nierenberg and Jastrow denied the scientific evidence, contributed to a strategy of delay, and thereby helped to bring about the situation they most dreaded.<ref name=ocmerch>{{harvnb|Oreskes|Conway|2010|pp=248–255}}</ref> The authors have a strong doubt about the ability of the media to differentiate between false truth and the actual science in question; however, they stop short of endorsing censorship in the name of science.<ref name ="RG" /> The journalistic norm of balanced reporting has helped, according to the authors, to amplify the misleading messages of the contrarians. Oreskes and Conway state: "small numbers of people can have large, negative impacts, especially if they are organised, determined and have access to power".<ref name=rm>{{cite news |author=McKie, Robin |title=A dark ideology is driving those who deny climate change |url=https://www.theguardian.com/commentisfree/2010/aug/01/climate-change-robin-mckie |newspaper=The Guardian |date=August 1, 2010 }}</ref>

The main conclusion of the book is that there would have been more progress in policymaking, if not for the influence of the contrarian "experts", which tried on ideological reasons to undermine trust in the science base for regulation.<ref name="RG">{{cite journal|last1=Grundmann|first1=Reiner|title=Debunking sceptical propaganda|journal=BioSocieties|date=29 August 2013|volume=8|issue=3|pages=370–374|doi=10.1057/biosoc.2013.15|url=https://www.academia.edu/4754580/Debunking_skeptical_propaganda_Book_review_of_Oreskes_Conway_Merchants_of_Doubt}}</ref> Similar conclusions were already drawn, among others on [[Frederick Seitz]] and [[William Nierenberg]] in the book ''[[Requiem for a Species|Requiem for a Species: Why We Resist the Truth about Climate Change]]'' (2010) by Australian academic [[Clive Hamilton]].

==Reception==

[[Philip Kitcher]] in ''[[Science (magazine)|Science]]'' says that Naomi Oreskes and Erik Conway are "two outstanding historians".<ref name=pk/> He calls ''Merchants of Doubt'' a "fascinating and important study". Kitcher says that the apparently harsh claims against Nierenberg, Seitz, and Singer are "justified through a powerful dissection of the ways in which prominent climate scientists, such as [[Roger Revelle]] and [[Ben Santer]], were exploited or viciously attacked in the press".<ref name=pk/>

In ''[[The Christian Science Monitor]]'', Will Buchanan says that ''Merchants of Doubt'' is exhaustively researched and documented, and may be one of the most important books of 2010. Oreskes and Conway are seen to demonstrate that the doubt merchants are not "objective scientists" as the term is popularly understood. Instead, they are "science-speaking mercenaries" hired by corporations to process numbers to prove that the corporations’ products are safe and useful. Buchanan says they are salesmen, not scientists.<ref>Buchanan, Will (June 22, 2010). [http://www.csmonitor.com/Books/Book-Reviews/2010/0622/Merchants-of-Doubt Merchants of Doubt: How “scientific” misinformation campaigns sold untruths to consumers] ''The Christian Science Monitor''.</ref>

Bud Ward published a review of the book in ''The Yale Forum on Climate and the Media''. He wrote that Oreskes and Conway use a combination of thorough scholarly research combined with writing reminiscent of the best investigative journalism, to "unravel deep common links to past environmental and public health controversies".<ref name="Ward">Ward, Bud (July 8, 2010). [http://www.yaleclimatemediaforum.org/2010/07/merchants-of-doubt/ Reviews: Leaving No Doubt on Tobacco, Acid Rain, Climate Change], ''The Yale Forum on Climate and the Media''.</ref> In terms of climate science, the authors' leave "little doubt about their disdain for what they regard as the misuse and abuse of science by a small cabal of scientists they see as largely lacking in requisite climate science expertise".<ref name="Ward" />

Phil England writes in ''[[The Ecologist]]'' that the strength of the book is the rigour of the research and the detailed focus on key incidents. He said, however, that the climate change chapter is only 50 pages long, and recommends several other books for readers who want to get a broader picture of this aspect: [[Jim Hoggan]]’s ''Climate Cover-Up'', [[George Monbiot]]’s ''Heat: How to Stop the Planet Burning'' and [[Ross Gelbspan]]’s ''The Heat is On'' and ''Boiling Point''. England also said that there is little coverage about the millions of dollars which [[Exxon Mobil]] has put into funding groups actively involved in promoting [[climate change denial]] and doubt.<ref>England, Phil (September 10, 2010). [http://www.theecologist.org/reviews/books/592288/merchants_of_doubt.html Merchants of Doubt] ''[[The Ecologist]]''.</ref>

A review in ''[[The Economist]]'' calls this a powerful book which articulates the politics involved and the degree to which scientists have sometimes manufactured and exaggerated environmental uncertainties, but opines that the authors fail to fully explain how environmental action has still often proved possible despite countervailing factors.<ref>[http://www.economist.com/node/16374460 All guns blazing: A question of dodgy science], (June 17, 2010), ''[[The Economist]]''.</ref>

A review in ''[[Psychology Today]]'' drew parallels with the book and the contested medical claims and subsequent legal battle as depicted in the film [[Erin Brockovich (film)|Erin Brockovich (2000)]].<ref>[https://www.psychologytoday.com/blog/side-effects/201107/merchants-doubt Merchants of Doubt On Manufactured Controversy and Dissent in Science. Posted Jul 04, 2011]</ref> Naomi Oreske, has compared herself to [[Erin Brockovich]], describing what served as the motivated for writing the book, her "Erin Brockovich moment".<ref>[http://gelbspanfiles.com/?p=4195 To be Credible, you must Keep Your Story Straight, Pt 2: “Oreskes’ timeline problem”]</ref><ref>[http://culturesofenergy.com/ep-47-naomi-oreskes/ Ms Oreskes December 2016 Rice University CENHS podcast interview. c. 44:40]</ref>

[[Robert N. Proctor]], who coined the term "[[agnotology]]" to describe the study of culturally induced ignorance or doubt, wrote in ''[[American Scientist]]'' that ''Merchants of Doubt'' is a detailed and artfully written book. He set it in the context of other books which cover the "history of manufactured ignorance":<ref name="Proctor">Proctor, Robert (September–October 2010). [http://www.americanscientist.org/bookshelf/pub/manufactured-ignorance Book Review: Manufactured Ignorance], ''[[American Scientist]]''.</ref> [[David Michaels (epidemiologist)|David Michaels]]’s ''[[Doubt is their Product]]'' (2008), [[Chris Mooney (journalist)|Chris Mooney]]’s ''[[The Republican War on Science]]'' (2009), [[David Rosner]] and Gerald Markowitz’s ''[[Deceit and Denial]]'' (2002), and his own book ''[[Cancer Wars]]'' (1995).<ref name="Proctor" />

Robin McKie in ''[[The Guardian]]'' states that Oreskes and Conway deserve considerable praise for exposing the influence of a small group of [[Cold War]] ideologues. Their tactic of spreading doubt has confused the public about a series of key scientific issues such as global warming, even though scientists have actually become more certain about their research results. McKie says that ''Merchants of Doubt'' includes detailed notes on all sources used, is carefully paced, and is "my runaway contender for best science book of the year".<ref name=Mckie8>McKie, Robin (August 8, 2010). [https://www.theguardian.com/books/2010/aug/08/merchants-of-doubt-oreskes-conway "Merchants of Doubt by Naomi Oreskes and Erik M Conway".] ''The Guardian''.</ref>

Sociologist [[Reiner Grundmann]]'s review in ''[[BioSocieties]]'' journal, acknowledges that the book is well researched and factually based, but criticizes the book as being written in a black and white manner whereas historians should write a more nuanced description. The book depicts special interests and contrarians misleading the public as being mainly responsible for stopping action on policy. He says this shows a lack of basic understanding of the political process and the mechanisms of [[knowledge policy]], because the authors assume that public policy would follow on from an understanding of the science. While the book provides ''all the (formal) hallmarks of science'', Grundmann sees it less as a scholarly work than a passionate attack and overall as a problematic book.<ref name="RG" />

William O’Keefe and Jeff Kueter from the [[George C. Marshall Institute]], which was founded by Seitz,<ref>{{cite web|last1=Begley|first1=Sharon|title=Global Warming Deniers: A Well-Funded Machine|url=http://www.newsweek.com/global-warming-deniers-well-funded-machine-99295|website=Newsweek|date=4 August 2007|quote=...a central cog in the denial machine: the George C. Marshall Institute, a conservative think tank.}}</ref> say that although ''Merchants of Doubt'' has the appearance of a scholarly work, it discredits and undermines the reputations of people who in their lifetime contributed greatly to the American nation. They say that it does this by questioning their integrity, impugning their character, and questioning their judgement.<ref>{{cite web | last=O’Keefe | first= William |last2= Kueter| first2=Jeff | date=June 2010 | url=http://marshall.org/wp-content/uploads/2011/06/OKeefe-and-Kueter-Clouding-the-Truth-A-Critique-of-Merchants-of-Doubt.pdf |title=Clouding the Truth: A Critique of Merchants of Doubt |publisher=[[George C. Marshall Institute]] |work=Policy Outlook | quote=Although cloaked in the appearance of scholarly work, the book constitutes an effort to discredit and undermine the reputations of three deceased scientists who contributed greatly to our nation... This book questions their integrity, impugns their character, and questions their judgment on the basis of little more than faulty logic and preconceived opinion}}</ref>

==Authors==
[[File:Naomi Oreskes 2nd European TA conference in Berlin 2015 (cropped to collar).JPG |thumb|right |[[Naomi Oreskes]] (2015), co-author of ''Merchants of Doubt''.]]
Naomi Oreskes is Professor of History and Science Studies at Harvard University. She has degrees in geological science and a [[Doctor of Philosophy|Ph.D.]] in [[Geological]] Research and the History of Science. Her work came to public attention in 2004 with the publication of "The Scientific Consensus on Climate Change," in ''Science'', in which she wrote that there was no significant disagreement in the scientific community about the reality of global warming from human causes.<ref name=collins>[http://www.marcovigevani.com/upload/london_2008/Collins_Literary_London_2008_Rights_List.pdf Collins Literary Agency Rights Guide/March 2008]</ref> Erik M. Conway is the historian at [[NASA]]'s [[Jet Propulsion Laboratory]] at the [[California Institute of Technology]] in [[Pasadena, California|Pasadena]].<ref name=collins/>

==Counterargument==
In 2011, aerospace engineer [[Robert Zubrin]], most famous for penning ''[[The Case for Mars]]'', published a book length response a year after ''Merchants of Doubt'', titled ''Merchants of Despair: Radical Environmentalists, Criminal Pseudo-Scientists, and the Fatal Cult of Antihumanism'', the book traces the history of [[antihumanism]] over the last two centuries, from [[Thomas Malthus]] and the [[eugenics]] movement through to the [[Anti-nuclear movement|anti-nuclear]] and "alarmist" DDT and [[Global warming controversy|global warming]] campaigns. Zubrin argues that these movements, by means of pseudo-science, have caused deaths and by a number of methods, including that of statistical mis-treatments, have all attempted to gain oppressive political control through the restriction of human activities and freedom.<ref>[https://www.theobjectivestandard.com/issues/2012-fall/review-merchants-of-despair/
Review: Merchants of Despair, by Robert Zubrin
Ted Gray February 2, 2014 In ''The Objective Standard'' Fall 2012]</ref>

==See also==
* [[Climate change controversy]]
* [[Climate change policy of the United States]]
* ''[[Climate Capitalism]]''
* [[Fear, uncertainty and doubt]]
* [[Greenhouse Mafia]]
* [[Health effects of tobacco]]
* [[List of books about the politics of science]]
* [[List of scientists opposing the mainstream scientific assessment of global warming]] in contrast with [[Scientific opinion on climate change]]
* [[Media coverage of climate change]]
* [[Scientific consensus]]
* [[Tobacco control movement]]
* [[Tobacco politics]]

=== Other books on the same theme ===
* ''[[Doubt Is Their Product: How Industry's Assault on Science Threatens Your Health]]'' (2008) by [[David Michaels (epidemiologist)|David Michaels]]
* ''Climate Cover-Up: The Crusade to Deny Global Warming'' (2009) by James Hoggan and Richard Littlemore
* ''[[Climate Change Denial: Heads in the Sand]]'' (2011) by Haydn Washington and John Cook

==References==
{{Reflist|30em}}

==External links==
* {{official website|http://www.merchantsofdoubt.org/index.html}}
* [http://www.abc.net.au/rn/scienceshow/stories/2011/3101369.htm Merchants of Doubt], Public Lecture (2010), [[University of NSW]], ''The Science Show'', [[ABC Radio National]], January 8, 2011.

{{Portal bar|Global warming|Environment}}

[[Category:2010 books]]
[[Category:2010 in the environment]]
[[Category:21st-century history books]]
[[Category:History books about science]]
[[Category:History books about politics]]
[[Category:Climate change books]]
[[Category:Climate change skepticism and denial]]
[[Category:Environmental non-fiction books]]
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[[Category:Doubt]]

Merchants of Doubt

2017-12-11T13:29:24Z

Boundarylayer: /* Reception */ "Erin Brockovich moment"

{{About|the book|the film based on the book|Merchants of Doubt (film)}}
{{Use mdy dates|date=December 2015}}
{{good article}}
{{Infobox book
| name = Merchants of Doubt: How a Handful of Scientists Obscured the Truth on Issues from Tobacco Smoke to Global Warming
| image = Merchants of DOUBT.jpg
| image_size = 197px
| caption =
| author = [[Naomi Oreskes]], [[Erik M. Conway]]
| illustrator =
| cover_artist =
| country =
| series =
| subject = Scientists—Professional Ethics Science news—Moral and ethical aspects
| published = June 3, 2010 [[Bloomsbury Press]]
| media_type =
| pages = 355 pp.
| isbn = 978-1-59691-610-4
| oclc = 461631066
| dewey = 174.95
| congress = Q147 .O74 2010
}}

'''''Merchants of Doubt: How a Handful of Scientists Obscured the Truth on Issues from Tobacco Smoke to Global Warming''''' is a 2010 non-fiction book by American [[History of science|historians of science]] [[Naomi Oreskes]] and [[Erik M. Conway]]. It identifies parallels between the [[global warming controversy]] and earlier controversies over [[tobacco smoking]], [[acid rain]], [[DDT]], and the [[ozone depletion|hole in the ozone layer]]. Oreskes and Conway write that in each case "keeping the controversy alive" by spreading doubt and confusion after a scientific consensus had been reached, was the basic strategy of those opposing action.<ref name = stek>{{cite news |author=Steketee, Mike |title=Some sceptics make it a habit to be wrong |url=http://www.theaustralian.com.au/national-affairs/some-sceptics-make-it-a-habit-to-be-wrong/story-fn59niix-1225956414538 |newspaper=[[The Australian]] |date=November 20, 2010 }}</ref> In particular, they say that [[Fred Seitz]], [[Fred Singer]], and a few other [[contrarian]] scientists joined forces with conservative [[think tank]]s and private corporations to challenge the scientific consensus on many contemporary issues.<ref>{{cite book |first1=Naomi |last1=Oreskes |first2=Erik M. |last2=Conway |title=Merchants of Doubt: How a Handful of Scientists Obscured the Truth on Issues from Tobacco Smoke to Global Warming |url=https://books.google.com/books?id=fpMh3nh3JI0C&pg=PP4 |year=2010 |publisher=Bloomsbury Press |isbn=978-1-59691-610-4 |page=6 |ref=harv}} [http://www.merchantsofdoubt.org/index.html merchantsofdoubt.org]</ref>

The [[George C. Marshall Institute]] and Fred Singer, two of the subjects, have been critical of the book. Other reviewers have been more favorable. One reviewer said that ''Merchants of Doubt'' is exhaustively researched and documented, and may be one of the most important books of 2010. Another reviewer saw the book as his choice for best [[science book]] of the year.<ref name=Mckie8/> It was made into a film, ''[[Merchants of Doubt (film)|Merchants of Doubt]]'', directed by [[Robert Kenner]], released in 2014.<ref>{{cite web | url=http://sonyclassics.com/merchantsofdoubt/ | title=Merchants of Doubt | publisher=Sony Pictures Classics | accessdate=March 8, 2015}}</ref>

==Themes==
[[File:S Fred Singer 2011.jpg |thumb|right |[[Fred Singer]] (2011), a prominent opponent of greenhouse gas regulation.]]
Oreskes and Conway write that a handful of [[Conservatism in the United States|politically conservative]] scientists, with strong ties to particular industries, have "played a disproportionate role in debates about controversial questions".<ref name=pk/> The authors write that this has resulted in "deliberate obfuscation" of the issues which has had an influence on [[Public opinion on climate change|public opinion]] and [[Climate change policy of the United States|policy-making]].<ref name=pk>{{cite journal |author=Kitcher, Philip |authorlink=Philip Kitcher |title=The Climate Change Debates |journal=[[Science (journal)|Science]] |volume=328 |issue=5983 |pages=1231–2 |date=June 4, 2010 |doi=10.1126/science.1189312 |url=http://www.sciencemag.org/cgi/content/full/328/5983/1230-a }}</ref>

The book criticizes the so-called Merchants of Doubt, some predominantly American science key players, above all [[William Nierenberg|Bill Nierenberg]], [[Fred Seitz]], and [[Fred Singer]]. All three are physicists: Singer was a [[rocket scientist]], whereas Nierenberg and Seitz worked on the atomic bomb.<ref name=sb>{{cite news |author=Brown, Seth |title='Merchants of Doubt' delves into contrarian scientists |url=https://www.usatoday.com/money/books/reviews/2010-06-01-deathmerchants01_ST_N.htm |newspaper=[[USA Today]] |date=May 31, 2010 }}</ref> They have been active on topics like acid rain, tobacco smoking, global warming and pesticides. The book claims that these scientists have challenged and diluted the [[scientific consensus]] in the various fields, as of the [[dangers of smoking]], the effects of acid rain, the existence of the ozone hole, and the existence of [[anthropogenic climate change]].<ref name=pk/> Seitz and Singer have been involved with institutions such as [[The Heritage Foundation]], [[Competitive Enterprise Institute]] and [[George C. Marshall Institute]] in the United States. Funded by [[corporation]]s and conservative [[Foundation (United States law)|foundations]], these organizations have opposed many forms of [[Economic interventionism|state intervention]] or regulation of U.S. citizens. The book lists similar tactics in each case: "discredit the science, disseminate false information, spread confusion, and promote doubt".<ref name=rm/>

The book states that Seitz, Singer, Nierenberg and [[Robert Jastrow]] were all fiercely [[Anti-communism|anti-communist]] and they viewed government regulation as a step towards [[socialism]] and [[communism]]. The authors argue that, with the [[collapse of the Soviet Union]], they looked for another great threat to free market capitalism and found it in environmentalism. They feared that an over-reaction to environmental problems would lead to heavy-handed government intervention in the marketplace and intrusion into people's lives.<ref name=ocmerch/> Oreskes and Conway state that the longer the delay the worse these problems get, and the more likely it is that governments will need to take the draconian measures that conservatives and [[market fundamentalism|market fundamentalists]] most fear. They say that Seitz, Singer, Nierenberg and Jastrow denied the scientific evidence, contributed to a strategy of delay, and thereby helped to bring about the situation they most dreaded.<ref name=ocmerch>{{harvnb|Oreskes|Conway|2010|pp=248–255}}</ref> The authors have a strong doubt about the ability of the media to differentiate between false truth and the actual science in question; however, they stop short of endorsing censorship in the name of science.<ref name ="RG" /> The journalistic norm of balanced reporting has helped, according to the authors, to amplify the misleading messages of the contrarians. Oreskes and Conway state: "small numbers of people can have large, negative impacts, especially if they are organised, determined and have access to power".<ref name=rm>{{cite news |author=McKie, Robin |title=A dark ideology is driving those who deny climate change |url=https://www.theguardian.com/commentisfree/2010/aug/01/climate-change-robin-mckie |newspaper=The Guardian |date=August 1, 2010 }}</ref>

The main conclusion of the book is that there would have been more progress in policymaking, if not for the influence of the contrarian "experts", which tried on ideological reasons to undermine trust in the science base for regulation.<ref name="RG">{{cite journal|last1=Grundmann|first1=Reiner|title=Debunking sceptical propaganda|journal=BioSocieties|date=29 August 2013|volume=8|issue=3|pages=370–374|doi=10.1057/biosoc.2013.15|url=https://www.academia.edu/4754580/Debunking_skeptical_propaganda_Book_review_of_Oreskes_Conway_Merchants_of_Doubt}}</ref> Similar conclusions were already drawn, among others on [[Frederick Seitz]] and [[William Nierenberg]] in the book ''[[Requiem for a Species|Requiem for a Species: Why We Resist the Truth about Climate Change]]'' (2010) by Australian academic [[Clive Hamilton]].

==Reception==

[[Philip Kitcher]] in ''[[Science (magazine)|Science]]'' says that Naomi Oreskes and Erik Conway are "two outstanding historians".<ref name=pk/> He calls ''Merchants of Doubt'' a "fascinating and important study". Kitcher says that the apparently harsh claims against Nierenberg, Seitz, and Singer are "justified through a powerful dissection of the ways in which prominent climate scientists, such as [[Roger Revelle]] and [[Ben Santer]], were exploited or viciously attacked in the press".<ref name=pk/>

In ''[[The Christian Science Monitor]]'', Will Buchanan says that ''Merchants of Doubt'' is exhaustively researched and documented, and may be one of the most important books of 2010. Oreskes and Conway are seen to demonstrate that the doubt merchants are not "objective scientists" as the term is popularly understood. Instead, they are "science-speaking mercenaries" hired by corporations to process numbers to prove that the corporations’ products are safe and useful. Buchanan says they are salesmen, not scientists.<ref>Buchanan, Will (June 22, 2010). [http://www.csmonitor.com/Books/Book-Reviews/2010/0622/Merchants-of-Doubt Merchants of Doubt: How “scientific” misinformation campaigns sold untruths to consumers] ''The Christian Science Monitor''.</ref>

Bud Ward published a review of the book in ''The Yale Forum on Climate and the Media''. He wrote that Oreskes and Conway use a combination of thorough scholarly research combined with writing reminiscent of the best investigative journalism, to "unravel deep common links to past environmental and public health controversies".<ref name="Ward">Ward, Bud (July 8, 2010). [http://www.yaleclimatemediaforum.org/2010/07/merchants-of-doubt/ Reviews: Leaving No Doubt on Tobacco, Acid Rain, Climate Change], ''The Yale Forum on Climate and the Media''.</ref> In terms of climate science, the authors' leave "little doubt about their disdain for what they regard as the misuse and abuse of science by a small cabal of scientists they see as largely lacking in requisite climate science expertise".<ref name="Ward" />

Phil England writes in ''[[The Ecologist]]'' that the strength of the book is the rigour of the research and the detailed focus on key incidents. He said, however, that the climate change chapter is only 50 pages long, and recommends several other books for readers who want to get a broader picture of this aspect: [[Jim Hoggan]]’s ''Climate Cover-Up'', [[George Monbiot]]’s ''Heat: How to Stop the Planet Burning'' and [[Ross Gelbspan]]’s ''The Heat is On'' and ''Boiling Point''. England also said that there is little coverage about the millions of dollars which [[Exxon Mobil]] has put into funding groups actively involved in promoting [[climate change denial]] and doubt.<ref>England, Phil (September 10, 2010). [http://www.theecologist.org/reviews/books/592288/merchants_of_doubt.html Merchants of Doubt] ''[[The Ecologist]]''.</ref>

A review in ''[[The Economist]]'' calls this a powerful book which articulates the politics involved and the degree to which scientists have sometimes manufactured and exaggerated environmental uncertainties, but opines that the authors fail to fully explain how environmental action has still often proved possible despite countervailing factors.<ref>[http://www.economist.com/node/16374460 All guns blazing: A question of dodgy science], (June 17, 2010), ''[[The Economist]]''.</ref>

A review in ''[[Psychology Today]]'' drew parallels with the book and the contested medical claims and subsequent legal battle as depicted in the film [[Erin Brockovich (film)|Erin Brockovich (2000)]].<ref>https://www.psychologytoday.com/blog/side-effects/201107/merchants-doubt Merchants of Doubt On Manufactured Controversy and Dissent in Science. Posted Jul 04, 2011]</ref> Naomi Oreske, has compared herself to [[Erin Brockovich]], describing what served as the motivated for writing the book, her "Erin Brockovich moment".<ref>[http://gelbspanfiles.com/?p=4195 To be Credible, you must Keep Your Story Straight, Pt 2: “Oreskes’ timeline problem”]</ref><ref>[http://culturesofenergy.com/ep-47-naomi-oreskes/ Ms Oreskes December 2016 Rice University CENHS podcast interview. c. 44:40]</ref>

[[Robert N. Proctor]], who coined the term "[[agnotology]]" to describe the study of culturally induced ignorance or doubt, wrote in ''[[American Scientist]]'' that ''Merchants of Doubt'' is a detailed and artfully written book. He set it in the context of other books which cover the "history of manufactured ignorance":<ref name="Proctor">Proctor, Robert (September–October 2010). [http://www.americanscientist.org/bookshelf/pub/manufactured-ignorance Book Review: Manufactured Ignorance], ''[[American Scientist]]''.</ref> [[David Michaels (epidemiologist)|David Michaels]]’s ''[[Doubt is their Product]]'' (2008), [[Chris Mooney (journalist)|Chris Mooney]]’s ''[[The Republican War on Science]]'' (2009), [[David Rosner]] and Gerald Markowitz’s ''[[Deceit and Denial]]'' (2002), and his own book ''[[Cancer Wars]]'' (1995).<ref name="Proctor" />

Robin McKie in ''[[The Guardian]]'' states that Oreskes and Conway deserve considerable praise for exposing the influence of a small group of [[Cold War]] ideologues. Their tactic of spreading doubt has confused the public about a series of key scientific issues such as global warming, even though scientists have actually become more certain about their research results. McKie says that ''Merchants of Doubt'' includes detailed notes on all sources used, is carefully paced, and is "my runaway contender for best science book of the year".<ref name=Mckie8>McKie, Robin (August 8, 2010). [https://www.theguardian.com/books/2010/aug/08/merchants-of-doubt-oreskes-conway "Merchants of Doubt by Naomi Oreskes and Erik M Conway".] ''The Guardian''.</ref>

Sociologist [[Reiner Grundmann]]'s review in ''[[BioSocieties]]'' journal, acknowledges that the book is well researched and factually based, but criticizes the book as being written in a black and white manner whereas historians should write a more nuanced description. The book depicts special interests and contrarians misleading the public as being mainly responsible for stopping action on policy. He says this shows a lack of basic understanding of the political process and the mechanisms of [[knowledge policy]], because the authors assume that public policy would follow on from an understanding of the science. While the book provides ''all the (formal) hallmarks of science'', Grundmann sees it less as a scholarly work than a passionate attack and overall as a problematic book.<ref name="RG" />

William O’Keefe and Jeff Kueter from the [[George C. Marshall Institute]], which was founded by Seitz,<ref>{{cite web|last1=Begley|first1=Sharon|title=Global Warming Deniers: A Well-Funded Machine|url=http://www.newsweek.com/global-warming-deniers-well-funded-machine-99295|website=Newsweek|date=4 August 2007|quote=...a central cog in the denial machine: the George C. Marshall Institute, a conservative think tank.}}</ref> say that although ''Merchants of Doubt'' has the appearance of a scholarly work, it discredits and undermines the reputations of people who in their lifetime contributed greatly to the American nation. They say that it does this by questioning their integrity, impugning their character, and questioning their judgement.<ref>{{cite web | last=O’Keefe | first= William |last2= Kueter| first2=Jeff | date=June 2010 | url=http://marshall.org/wp-content/uploads/2011/06/OKeefe-and-Kueter-Clouding-the-Truth-A-Critique-of-Merchants-of-Doubt.pdf |title=Clouding the Truth: A Critique of Merchants of Doubt |publisher=[[George C. Marshall Institute]] |work=Policy Outlook | quote=Although cloaked in the appearance of scholarly work, the book constitutes an effort to discredit and undermine the reputations of three deceased scientists who contributed greatly to our nation... This book questions their integrity, impugns their character, and questions their judgment on the basis of little more than faulty logic and preconceived opinion}}</ref>

==Authors==
[[File:Naomi Oreskes 2nd European TA conference in Berlin 2015 (cropped to collar).JPG |thumb|right |[[Naomi Oreskes]] (2015), co-author of ''Merchants of Doubt''.]]
Naomi Oreskes is Professor of History and Science Studies at Harvard University. She has degrees in geological science and a [[Doctor of Philosophy|Ph.D.]] in [[Geological]] Research and the History of Science. Her work came to public attention in 2004 with the publication of "The Scientific Consensus on Climate Change," in ''Science'', in which she wrote that there was no significant disagreement in the scientific community about the reality of global warming from human causes.<ref name=collins>[http://www.marcovigevani.com/upload/london_2008/Collins_Literary_London_2008_Rights_List.pdf Collins Literary Agency Rights Guide/March 2008]</ref> Erik M. Conway is the historian at [[NASA]]'s [[Jet Propulsion Laboratory]] at the [[California Institute of Technology]] in [[Pasadena, California|Pasadena]].<ref name=collins/>

==Counterargument==
In 2011, aerospace engineer [[Robert Zubrin]], most famous for penning ''[[The Case for Mars]]'', published a book length response a year after ''Merchants of Doubt'', titled ''Merchants of Despair: Radical Environmentalists, Criminal Pseudo-Scientists, and the Fatal Cult of Antihumanism'', the book traces the history of [[antihumanism]] over the last two centuries, from [[Thomas Malthus]] and the [[eugenics]] movement through to the [[Anti-nuclear movement|anti-nuclear]] and "alarmist" DDT and [[Global warming controversy|global warming]] campaigns. Zubrin argues that these movements, by means of pseudo-science, have caused deaths and by a number of methods, including that of statistical mis-treatments, have all attempted to gain oppressive political control through the restriction of human activities and freedom.<ref>[https://www.theobjectivestandard.com/issues/2012-fall/review-merchants-of-despair/
Review: Merchants of Despair, by Robert Zubrin
Ted Gray February 2, 2014 In ''The Objective Standard'' Fall 2012]</ref>

==See also==
* [[Climate change controversy]]
* [[Climate change policy of the United States]]
* ''[[Climate Capitalism]]''
* [[Fear, uncertainty and doubt]]
* [[Greenhouse Mafia]]
* [[Health effects of tobacco]]
* [[List of books about the politics of science]]
* [[List of scientists opposing the mainstream scientific assessment of global warming]] in contrast with [[Scientific opinion on climate change]]
* [[Media coverage of climate change]]
* [[Scientific consensus]]
* [[Tobacco control movement]]
* [[Tobacco politics]]

=== Other books on the same theme ===
* ''[[Doubt Is Their Product: How Industry's Assault on Science Threatens Your Health]]'' (2008) by [[David Michaels (epidemiologist)|David Michaels]]
* ''Climate Cover-Up: The Crusade to Deny Global Warming'' (2009) by James Hoggan and Richard Littlemore
* ''[[Climate Change Denial: Heads in the Sand]]'' (2011) by Haydn Washington and John Cook

==References==
{{Reflist|30em}}

==External links==
* {{official website|http://www.merchantsofdoubt.org/index.html}}
* [http://www.abc.net.au/rn/scienceshow/stories/2011/3101369.htm Merchants of Doubt], Public Lecture (2010), [[University of NSW]], ''The Science Show'', [[ABC Radio National]], January 8, 2011.

{{Portal bar|Global warming|Environment}}

[[Category:2010 books]]
[[Category:2010 in the environment]]
[[Category:21st-century history books]]
[[Category:History books about science]]
[[Category:History books about politics]]
[[Category:Climate change books]]
[[Category:Climate change skepticism and denial]]
[[Category:Environmental non-fiction books]]
[[Category:Political books]]
[[Category:Books about the politics of science]]
[[Category:Books adapted into films]]
[[Category:Professional ethics]]
[[Category:Doubt]]

Merchants of Doubt

2017-12-11T12:00:50Z

Boundarylayer: /* Counterargument */ ''Merchants of doubt'' published 2010, While Zubrin's ''Merchants of Despair'', was published 1 year later and you argue it wasn't a reply or wasn't written as a counter-argument? Are you being facetious?

{{About|the book|the film based on the book|Merchants of Doubt (film)}}
{{Use mdy dates|date=December 2015}}
{{good article}}
{{Infobox book
| name = Merchants of Doubt: How a Handful of Scientists Obscured the Truth on Issues from Tobacco Smoke to Global Warming
| image = Merchants of DOUBT.jpg
| image_size = 197px
| caption =
| author = [[Naomi Oreskes]], [[Erik M. Conway]]
| illustrator =
| cover_artist =
| country =
| series =
| subject = Scientists—Professional Ethics Science news—Moral and ethical aspects
| published = June 3, 2010 [[Bloomsbury Press]]
| media_type =
| pages = 355 pp.
| isbn = 978-1-59691-610-4
| oclc = 461631066
| dewey = 174.95
| congress = Q147 .O74 2010
}}

'''''Merchants of Doubt: How a Handful of Scientists Obscured the Truth on Issues from Tobacco Smoke to Global Warming''''' is a 2010 non-fiction book by American [[History of science|historians of science]] [[Naomi Oreskes]] and [[Erik M. Conway]]. It identifies parallels between the [[global warming controversy]] and earlier controversies over [[tobacco smoking]], [[acid rain]], [[DDT]], and the [[ozone depletion|hole in the ozone layer]]. Oreskes and Conway write that in each case "keeping the controversy alive" by spreading doubt and confusion after a scientific consensus had been reached, was the basic strategy of those opposing action.<ref name = stek>{{cite news |author=Steketee, Mike |title=Some sceptics make it a habit to be wrong |url=http://www.theaustralian.com.au/national-affairs/some-sceptics-make-it-a-habit-to-be-wrong/story-fn59niix-1225956414538 |newspaper=[[The Australian]] |date=November 20, 2010 }}</ref> In particular, they say that [[Fred Seitz]], [[Fred Singer]], and a few other [[contrarian]] scientists joined forces with conservative [[think tank]]s and private corporations to challenge the scientific consensus on many contemporary issues.<ref>{{cite book |first1=Naomi |last1=Oreskes |first2=Erik M. |last2=Conway |title=Merchants of Doubt: How a Handful of Scientists Obscured the Truth on Issues from Tobacco Smoke to Global Warming |url=https://books.google.com/books?id=fpMh3nh3JI0C&pg=PP4 |year=2010 |publisher=Bloomsbury Press |isbn=978-1-59691-610-4 |page=6 |ref=harv}} [http://www.merchantsofdoubt.org/index.html merchantsofdoubt.org]</ref>

The [[George C. Marshall Institute]] and Fred Singer, two of the subjects, have been critical of the book. Other reviewers have been more favorable. One reviewer said that ''Merchants of Doubt'' is exhaustively researched and documented, and may be one of the most important books of 2010. Another reviewer saw the book as his choice for best [[science book]] of the year.<ref name=Mckie8/> It was made into a film, ''[[Merchants of Doubt (film)|Merchants of Doubt]]'', directed by [[Robert Kenner]], released in 2014.<ref>{{cite web | url=http://sonyclassics.com/merchantsofdoubt/ | title=Merchants of Doubt | publisher=Sony Pictures Classics | accessdate=March 8, 2015}}</ref>

==Themes==
[[File:S Fred Singer 2011.jpg |thumb|right |[[Fred Singer]] (2011), a prominent opponent of greenhouse gas regulation.]]
Oreskes and Conway write that a handful of [[Conservatism in the United States|politically conservative]] scientists, with strong ties to particular industries, have "played a disproportionate role in debates about controversial questions".<ref name=pk/> The authors write that this has resulted in "deliberate obfuscation" of the issues which has had an influence on [[Public opinion on climate change|public opinion]] and [[Climate change policy of the United States|policy-making]].<ref name=pk>{{cite journal |author=Kitcher, Philip |authorlink=Philip Kitcher |title=The Climate Change Debates |journal=[[Science (journal)|Science]] |volume=328 |issue=5983 |pages=1231–2 |date=June 4, 2010 |doi=10.1126/science.1189312 |url=http://www.sciencemag.org/cgi/content/full/328/5983/1230-a }}</ref>

The book criticizes the so-called Merchants of Doubt, some predominantly American science key players, above all [[William Nierenberg|Bill Nierenberg]], [[Fred Seitz]], and [[Fred Singer]]. All three are physicists: Singer was a [[rocket scientist]], whereas Nierenberg and Seitz worked on the atomic bomb.<ref name=sb>{{cite news |author=Brown, Seth |title='Merchants of Doubt' delves into contrarian scientists |url=https://www.usatoday.com/money/books/reviews/2010-06-01-deathmerchants01_ST_N.htm |newspaper=[[USA Today]] |date=May 31, 2010 }}</ref> They have been active on topics like acid rain, tobacco smoking, global warming and pesticides. The book claims that these scientists have challenged and diluted the [[scientific consensus]] in the various fields, as of the [[dangers of smoking]], the effects of acid rain, the existence of the ozone hole, and the existence of [[anthropogenic climate change]].<ref name=pk/> Seitz and Singer have been involved with institutions such as [[The Heritage Foundation]], [[Competitive Enterprise Institute]] and [[George C. Marshall Institute]] in the United States. Funded by [[corporation]]s and conservative [[Foundation (United States law)|foundations]], these organizations have opposed many forms of [[Economic interventionism|state intervention]] or regulation of U.S. citizens. The book lists similar tactics in each case: "discredit the science, disseminate false information, spread confusion, and promote doubt".<ref name=rm/>

The book states that Seitz, Singer, Nierenberg and [[Robert Jastrow]] were all fiercely [[Anti-communism|anti-communist]] and they viewed government regulation as a step towards [[socialism]] and [[communism]]. The authors argue that, with the [[collapse of the Soviet Union]], they looked for another great threat to free market capitalism and found it in environmentalism. They feared that an over-reaction to environmental problems would lead to heavy-handed government intervention in the marketplace and intrusion into people's lives.<ref name=ocmerch/> Oreskes and Conway state that the longer the delay the worse these problems get, and the more likely it is that governments will need to take the draconian measures that conservatives and [[market fundamentalism|market fundamentalists]] most fear. They say that Seitz, Singer, Nierenberg and Jastrow denied the scientific evidence, contributed to a strategy of delay, and thereby helped to bring about the situation they most dreaded.<ref name=ocmerch>{{harvnb|Oreskes|Conway|2010|pp=248–255}}</ref> The authors have a strong doubt about the ability of the media to differentiate between false truth and the actual science in question; however, they stop short of endorsing censorship in the name of science.<ref name ="RG" /> The journalistic norm of balanced reporting has helped, according to the authors, to amplify the misleading messages of the contrarians. Oreskes and Conway state: "small numbers of people can have large, negative impacts, especially if they are organised, determined and have access to power".<ref name=rm>{{cite news |author=McKie, Robin |title=A dark ideology is driving those who deny climate change |url=https://www.theguardian.com/commentisfree/2010/aug/01/climate-change-robin-mckie |newspaper=The Guardian |date=August 1, 2010 }}</ref>

The main conclusion of the book is that there would have been more progress in policymaking, if not for the influence of the contrarian "experts", which tried on ideological reasons to undermine trust in the science base for regulation.<ref name="RG">{{cite journal|last1=Grundmann|first1=Reiner|title=Debunking sceptical propaganda|journal=BioSocieties|date=29 August 2013|volume=8|issue=3|pages=370–374|doi=10.1057/biosoc.2013.15|url=https://www.academia.edu/4754580/Debunking_skeptical_propaganda_Book_review_of_Oreskes_Conway_Merchants_of_Doubt}}</ref> Similar conclusions were already drawn, among others on [[Frederick Seitz]] and [[William Nierenberg]] in the book ''[[Requiem for a Species|Requiem for a Species: Why We Resist the Truth about Climate Change]]'' (2010) by Australian academic [[Clive Hamilton]].

==Reception==

[[Philip Kitcher]] in ''[[Science (magazine)|Science]]'' says that Naomi Oreskes and Erik Conway are "two outstanding historians".<ref name=pk/> He calls ''Merchants of Doubt'' a "fascinating and important study". Kitcher says that the apparently harsh claims against Nierenberg, Seitz, and Singer are "justified through a powerful dissection of the ways in which prominent climate scientists, such as [[Roger Revelle]] and [[Ben Santer]], were exploited or viciously attacked in the press".<ref name=pk/>

In ''[[The Christian Science Monitor]]'', Will Buchanan says that ''Merchants of Doubt'' is exhaustively researched and documented, and may be one of the most important books of 2010. Oreskes and Conway are seen to demonstrate that the doubt merchants are not "objective scientists" as the term is popularly understood. Instead, they are "science-speaking mercenaries" hired by corporations to process numbers to prove that the corporations’ products are safe and useful. Buchanan says they are salesmen, not scientists.<ref>Buchanan, Will (June 22, 2010). [http://www.csmonitor.com/Books/Book-Reviews/2010/0622/Merchants-of-Doubt Merchants of Doubt: How “scientific” misinformation campaigns sold untruths to consumers] ''The Christian Science Monitor''.</ref>

Bud Ward published a review of the book in ''The Yale Forum on Climate and the Media''. He wrote that Oreskes and Conway use a combination of thorough scholarly research combined with writing reminiscent of the best investigative journalism, to "unravel deep common links to past environmental and public health controversies".<ref name="Ward">Ward, Bud (July 8, 2010). [http://www.yaleclimatemediaforum.org/2010/07/merchants-of-doubt/ Reviews: Leaving No Doubt on Tobacco, Acid Rain, Climate Change], ''The Yale Forum on Climate and the Media''.</ref> In terms of climate science, the authors' leave "little doubt about their disdain for what they regard as the misuse and abuse of science by a small cabal of scientists they see as largely lacking in requisite climate science expertise".<ref name="Ward" />

Phil England writes in ''[[The Ecologist]]'' that the strength of the book is the rigour of the research and the detailed focus on key incidents. He said, however, that the climate change chapter is only 50 pages long, and recommends several other books for readers who want to get a broader picture of this aspect: [[Jim Hoggan]]’s ''Climate Cover-Up'', [[George Monbiot]]’s ''Heat: How to Stop the Planet Burning'' and [[Ross Gelbspan]]’s ''The Heat is On'' and ''Boiling Point''. England also said that there is little coverage about the millions of dollars which [[Exxon Mobil]] has put into funding groups actively involved in promoting [[climate change denial]] and doubt.<ref>England, Phil (September 10, 2010). [http://www.theecologist.org/reviews/books/592288/merchants_of_doubt.html Merchants of Doubt] ''[[The Ecologist]]''.</ref>

A review in ''[[The Economist]]'' calls this a powerful book which articulates the politics involved and the degree to which scientists have sometimes manufactured and exaggerated environmental uncertainties, but opines that the authors fail to fully explain how environmental action has still often proved possible despite countervailing factors.<ref>[http://www.economist.com/node/16374460 All guns blazing: A question of dodgy science], (June 17, 2010), ''[[The Economist]]''.</ref>

[[Robert N. Proctor]], who coined the term "[[agnotology]]" to describe the study of culturally induced ignorance or doubt, wrote in ''[[American Scientist]]'' that ''Merchants of Doubt'' is a detailed and artfully written book. He set it in the context of other books which cover the "history of manufactured ignorance":<ref name="Proctor">Proctor, Robert (September–October 2010). [http://www.americanscientist.org/bookshelf/pub/manufactured-ignorance Book Review: Manufactured Ignorance], ''[[American Scientist]]''.</ref> [[David Michaels (epidemiologist)|David Michaels]]’s ''[[Doubt is their Product]]'' (2008), [[Chris Mooney (journalist)|Chris Mooney]]’s ''[[The Republican War on Science]]'' (2009), [[David Rosner]] and Gerald Markowitz’s ''[[Deceit and Denial]]'' (2002), and his own book ''[[Cancer Wars]]'' (1995).<ref name="Proctor" />

Robin McKie in ''[[The Guardian]]'' states that Oreskes and Conway deserve considerable praise for exposing the influence of a small group of [[Cold War]] ideologues. Their tactic of spreading doubt has confused the public about a series of key scientific issues such as global warming, even though scientists have actually become more certain about their research results. McKie says that ''Merchants of Doubt'' includes detailed notes on all sources used, is carefully paced, and is "my runaway contender for best science book of the year".<ref name=Mckie8>McKie, Robin (August 8, 2010). [https://www.theguardian.com/books/2010/aug/08/merchants-of-doubt-oreskes-conway "Merchants of Doubt by Naomi Oreskes and Erik M Conway".] ''The Guardian''.</ref>

Sociologist [[Reiner Grundmann]]'s review in ''[[BioSocieties]]'' journal, acknowledges that the book is well researched and factually based, but criticizes the book as being written in a black and white manner whereas historians should write a more nuanced description. The book depicts special interests and contrarians misleading the public as being mainly responsible for stopping action on policy. He says this shows a lack of basic understanding of the political process and the mechanisms of [[knowledge policy]], because the authors assume that public policy would follow on from an understanding of the science. While the book provides ''all the (formal) hallmarks of science'', Grundmann sees it less as a scholarly work than a passionate attack and overall as a problematic book.<ref name="RG" />

William O’Keefe and Jeff Kueter from the [[George C. Marshall Institute]], which was founded by Seitz,<ref>{{cite web|last1=Begley|first1=Sharon|title=Global Warming Deniers: A Well-Funded Machine|url=http://www.newsweek.com/global-warming-deniers-well-funded-machine-99295|website=Newsweek|date=4 August 2007|quote=...a central cog in the denial machine: the George C. Marshall Institute, a conservative think tank.}}</ref> say that although ''Merchants of Doubt'' has the appearance of a scholarly work, it discredits and undermines the reputations of people who in their lifetime contributed greatly to the American nation. They say that it does this by questioning their integrity, impugning their character, and questioning their judgement.<ref>{{cite web | last=O’Keefe | first= William |last2= Kueter| first2=Jeff | date=June 2010 | url=http://marshall.org/wp-content/uploads/2011/06/OKeefe-and-Kueter-Clouding-the-Truth-A-Critique-of-Merchants-of-Doubt.pdf |title=Clouding the Truth: A Critique of Merchants of Doubt |publisher=[[George C. Marshall Institute]] |work=Policy Outlook | quote=Although cloaked in the appearance of scholarly work, the book constitutes an effort to discredit and undermine the reputations of three deceased scientists who contributed greatly to our nation... This book questions their integrity, impugns their character, and questions their judgment on the basis of little more than faulty logic and preconceived opinion}}</ref>

==Authors==
[[File:Naomi Oreskes 2nd European TA conference in Berlin 2015 (cropped to collar).JPG |thumb|right |[[Naomi Oreskes]] (2015), co-author of ''Merchants of Doubt''.]]
Naomi Oreskes is Professor of History and Science Studies at Harvard University. She has degrees in geological science and a [[Doctor of Philosophy|Ph.D.]] in [[Geological]] Research and the History of Science. Her work came to public attention in 2004 with the publication of "The Scientific Consensus on Climate Change," in ''Science'', in which she wrote that there was no significant disagreement in the scientific community about the reality of global warming from human causes.<ref name=collins>[http://www.marcovigevani.com/upload/london_2008/Collins_Literary_London_2008_Rights_List.pdf Collins Literary Agency Rights Guide/March 2008]</ref> Erik M. Conway is the historian at [[NASA]]'s [[Jet Propulsion Laboratory]] at the [[California Institute of Technology]] in [[Pasadena, California|Pasadena]].<ref name=collins/>

==Counterargument==
In 2011, aerospace engineer [[Robert Zubrin]], most famous for penning ''[[The Case for Mars]]'', published a book length response a year after ''Merchants of Doubt'', titled ''Merchants of Despair: Radical Environmentalists, Criminal Pseudo-Scientists, and the Fatal Cult of Antihumanism'', the book traces the history of [[antihumanism]] over the last two centuries, from [[Thomas Malthus]] and the [[eugenics]] movement through to the [[Anti-nuclear movement|anti-nuclear]] and "alarmist" DDT and [[Global warming controversy|global warming]] campaigns. Zubrin argues that these movements, by means of pseudo-science, have caused deaths and by a number of methods, including that of statistical mis-treatments, have all attempted to gain oppressive political control through the restriction of human activities and freedom.<ref>[https://www.theobjectivestandard.com/issues/2012-fall/review-merchants-of-despair/
Review: Merchants of Despair, by Robert Zubrin
Ted Gray February 2, 2014 In ''The Objective Standard'' Fall 2012]</ref>

==See also==
* [[Climate change controversy]]
* [[Climate change policy of the United States]]
* ''[[Climate Capitalism]]''
* [[Fear, uncertainty and doubt]]
* [[Greenhouse Mafia]]
* [[Health effects of tobacco]]
* [[List of books about the politics of science]]
* [[List of scientists opposing the mainstream scientific assessment of global warming]] in contrast with [[Scientific opinion on climate change]]
* [[Media coverage of climate change]]
* [[Scientific consensus]]
* [[Tobacco control movement]]
* [[Tobacco politics]]

=== Other books on the same theme ===
* ''[[Doubt Is Their Product: How Industry's Assault on Science Threatens Your Health]]'' (2008) by [[David Michaels (epidemiologist)|David Michaels]]
* ''Climate Cover-Up: The Crusade to Deny Global Warming'' (2009) by James Hoggan and Richard Littlemore
* ''[[Climate Change Denial: Heads in the Sand]]'' (2011) by Haydn Washington and John Cook

==References==
{{Reflist|30em}}

==External links==
* {{official website|http://www.merchantsofdoubt.org/index.html}}
* [http://www.abc.net.au/rn/scienceshow/stories/2011/3101369.htm Merchants of Doubt], Public Lecture (2010), [[University of NSW]], ''The Science Show'', [[ABC Radio National]], January 8, 2011.

{{Portal bar|Global warming|Environment}}

[[Category:2010 books]]
[[Category:2010 in the environment]]
[[Category:21st-century history books]]
[[Category:History books about science]]
[[Category:History books about politics]]
[[Category:Climate change books]]
[[Category:Climate change skepticism and denial]]
[[Category:Environmental non-fiction books]]
[[Category:Political books]]
[[Category:Books about the politics of science]]
[[Category:Books adapted into films]]
[[Category:Professional ethics]]
[[Category:Doubt]]

Merchants of Doubt

2017-12-11T11:50:30Z

Boundarylayer: Undid revision 814793726 by Adrian J. Hunter (talk) Please take your argument to the talk page

{{About|the book|the film based on the book|Merchants of Doubt (film)}}
{{Use mdy dates|date=December 2015}}
{{good article}}
{{Infobox book
| name = Merchants of Doubt: How a Handful of Scientists Obscured the Truth on Issues from Tobacco Smoke to Global Warming
| image = Merchants of DOUBT.jpg
| image_size = 197px
| caption =
| author = [[Naomi Oreskes]], [[Erik M. Conway]]
| illustrator =
| cover_artist =
| country =
| series =
| subject = Scientists—Professional Ethics Science news—Moral and ethical aspects
| published = June 3, 2010 [[Bloomsbury Press]]
| media_type =
| pages = 355 pp.
| isbn = 978-1-59691-610-4
| oclc = 461631066
| dewey = 174.95
| congress = Q147 .O74 2010
}}

'''''Merchants of Doubt: How a Handful of Scientists Obscured the Truth on Issues from Tobacco Smoke to Global Warming''''' is a 2010 non-fiction book by American [[History of science|historians of science]] [[Naomi Oreskes]] and [[Erik M. Conway]]. It identifies parallels between the [[global warming controversy]] and earlier controversies over [[tobacco smoking]], [[acid rain]], [[DDT]], and the [[ozone depletion|hole in the ozone layer]]. Oreskes and Conway write that in each case "keeping the controversy alive" by spreading doubt and confusion after a scientific consensus had been reached, was the basic strategy of those opposing action.<ref name = stek>{{cite news |author=Steketee, Mike |title=Some sceptics make it a habit to be wrong |url=http://www.theaustralian.com.au/national-affairs/some-sceptics-make-it-a-habit-to-be-wrong/story-fn59niix-1225956414538 |newspaper=[[The Australian]] |date=November 20, 2010 }}</ref> In particular, they say that [[Fred Seitz]], [[Fred Singer]], and a few other [[contrarian]] scientists joined forces with conservative [[think tank]]s and private corporations to challenge the scientific consensus on many contemporary issues.<ref>{{cite book |first1=Naomi |last1=Oreskes |first2=Erik M. |last2=Conway |title=Merchants of Doubt: How a Handful of Scientists Obscured the Truth on Issues from Tobacco Smoke to Global Warming |url=https://books.google.com/books?id=fpMh3nh3JI0C&pg=PP4 |year=2010 |publisher=Bloomsbury Press |isbn=978-1-59691-610-4 |page=6 |ref=harv}} [http://www.merchantsofdoubt.org/index.html merchantsofdoubt.org]</ref>

The [[George C. Marshall Institute]] and Fred Singer, two of the subjects, have been critical of the book. Other reviewers have been more favorable. One reviewer said that ''Merchants of Doubt'' is exhaustively researched and documented, and may be one of the most important books of 2010. Another reviewer saw the book as his choice for best [[science book]] of the year.<ref name=Mckie8/> It was made into a film, ''[[Merchants of Doubt (film)|Merchants of Doubt]]'', directed by [[Robert Kenner]], released in 2014.<ref>{{cite web | url=http://sonyclassics.com/merchantsofdoubt/ | title=Merchants of Doubt | publisher=Sony Pictures Classics | accessdate=March 8, 2015}}</ref>

==Themes==
[[File:S Fred Singer 2011.jpg |thumb|right |[[Fred Singer]] (2011), a prominent opponent of greenhouse gas regulation.]]
Oreskes and Conway write that a handful of [[Conservatism in the United States|politically conservative]] scientists, with strong ties to particular industries, have "played a disproportionate role in debates about controversial questions".<ref name=pk/> The authors write that this has resulted in "deliberate obfuscation" of the issues which has had an influence on [[Public opinion on climate change|public opinion]] and [[Climate change policy of the United States|policy-making]].<ref name=pk>{{cite journal |author=Kitcher, Philip |authorlink=Philip Kitcher |title=The Climate Change Debates |journal=[[Science (journal)|Science]] |volume=328 |issue=5983 |pages=1231–2 |date=June 4, 2010 |doi=10.1126/science.1189312 |url=http://www.sciencemag.org/cgi/content/full/328/5983/1230-a }}</ref>

The book criticizes the so-called Merchants of Doubt, some predominantly American science key players, above all [[William Nierenberg|Bill Nierenberg]], [[Fred Seitz]], and [[Fred Singer]]. All three are physicists: Singer was a [[rocket scientist]], whereas Nierenberg and Seitz worked on the atomic bomb.<ref name=sb>{{cite news |author=Brown, Seth |title='Merchants of Doubt' delves into contrarian scientists |url=https://www.usatoday.com/money/books/reviews/2010-06-01-deathmerchants01_ST_N.htm |newspaper=[[USA Today]] |date=May 31, 2010 }}</ref> They have been active on topics like acid rain, tobacco smoking, global warming and pesticides. The book claims that these scientists have challenged and diluted the [[scientific consensus]] in the various fields, as of the [[dangers of smoking]], the effects of acid rain, the existence of the ozone hole, and the existence of [[anthropogenic climate change]].<ref name=pk/> Seitz and Singer have been involved with institutions such as [[The Heritage Foundation]], [[Competitive Enterprise Institute]] and [[George C. Marshall Institute]] in the United States. Funded by [[corporation]]s and conservative [[Foundation (United States law)|foundations]], these organizations have opposed many forms of [[Economic interventionism|state intervention]] or regulation of U.S. citizens. The book lists similar tactics in each case: "discredit the science, disseminate false information, spread confusion, and promote doubt".<ref name=rm/>

The book states that Seitz, Singer, Nierenberg and [[Robert Jastrow]] were all fiercely [[Anti-communism|anti-communist]] and they viewed government regulation as a step towards [[socialism]] and [[communism]]. The authors argue that, with the [[collapse of the Soviet Union]], they looked for another great threat to free market capitalism and found it in environmentalism. They feared that an over-reaction to environmental problems would lead to heavy-handed government intervention in the marketplace and intrusion into people's lives.<ref name=ocmerch/> Oreskes and Conway state that the longer the delay the worse these problems get, and the more likely it is that governments will need to take the draconian measures that conservatives and [[market fundamentalism|market fundamentalists]] most fear. They say that Seitz, Singer, Nierenberg and Jastrow denied the scientific evidence, contributed to a strategy of delay, and thereby helped to bring about the situation they most dreaded.<ref name=ocmerch>{{harvnb|Oreskes|Conway|2010|pp=248–255}}</ref> The authors have a strong doubt about the ability of the media to differentiate between false truth and the actual science in question; however, they stop short of endorsing censorship in the name of science.<ref name ="RG" /> The journalistic norm of balanced reporting has helped, according to the authors, to amplify the misleading messages of the contrarians. Oreskes and Conway state: "small numbers of people can have large, negative impacts, especially if they are organised, determined and have access to power".<ref name=rm>{{cite news |author=McKie, Robin |title=A dark ideology is driving those who deny climate change |url=https://www.theguardian.com/commentisfree/2010/aug/01/climate-change-robin-mckie |newspaper=The Guardian |date=August 1, 2010 }}</ref>

The main conclusion of the book is that there would have been more progress in policymaking, if not for the influence of the contrarian "experts", which tried on ideological reasons to undermine trust in the science base for regulation.<ref name="RG">{{cite journal|last1=Grundmann|first1=Reiner|title=Debunking sceptical propaganda|journal=BioSocieties|date=29 August 2013|volume=8|issue=3|pages=370–374|doi=10.1057/biosoc.2013.15|url=https://www.academia.edu/4754580/Debunking_skeptical_propaganda_Book_review_of_Oreskes_Conway_Merchants_of_Doubt}}</ref> Similar conclusions were already drawn, among others on [[Frederick Seitz]] and [[William Nierenberg]] in the book ''[[Requiem for a Species|Requiem for a Species: Why We Resist the Truth about Climate Change]]'' (2010) by Australian academic [[Clive Hamilton]].

==Reception==

[[Philip Kitcher]] in ''[[Science (magazine)|Science]]'' says that Naomi Oreskes and Erik Conway are "two outstanding historians".<ref name=pk/> He calls ''Merchants of Doubt'' a "fascinating and important study". Kitcher says that the apparently harsh claims against Nierenberg, Seitz, and Singer are "justified through a powerful dissection of the ways in which prominent climate scientists, such as [[Roger Revelle]] and [[Ben Santer]], were exploited or viciously attacked in the press".<ref name=pk/>

In ''[[The Christian Science Monitor]]'', Will Buchanan says that ''Merchants of Doubt'' is exhaustively researched and documented, and may be one of the most important books of 2010. Oreskes and Conway are seen to demonstrate that the doubt merchants are not "objective scientists" as the term is popularly understood. Instead, they are "science-speaking mercenaries" hired by corporations to process numbers to prove that the corporations’ products are safe and useful. Buchanan says they are salesmen, not scientists.<ref>Buchanan, Will (June 22, 2010). [http://www.csmonitor.com/Books/Book-Reviews/2010/0622/Merchants-of-Doubt Merchants of Doubt: How “scientific” misinformation campaigns sold untruths to consumers] ''The Christian Science Monitor''.</ref>

Bud Ward published a review of the book in ''The Yale Forum on Climate and the Media''. He wrote that Oreskes and Conway use a combination of thorough scholarly research combined with writing reminiscent of the best investigative journalism, to "unravel deep common links to past environmental and public health controversies".<ref name="Ward">Ward, Bud (July 8, 2010). [http://www.yaleclimatemediaforum.org/2010/07/merchants-of-doubt/ Reviews: Leaving No Doubt on Tobacco, Acid Rain, Climate Change], ''The Yale Forum on Climate and the Media''.</ref> In terms of climate science, the authors' leave "little doubt about their disdain for what they regard as the misuse and abuse of science by a small cabal of scientists they see as largely lacking in requisite climate science expertise".<ref name="Ward" />

Phil England writes in ''[[The Ecologist]]'' that the strength of the book is the rigour of the research and the detailed focus on key incidents. He said, however, that the climate change chapter is only 50 pages long, and recommends several other books for readers who want to get a broader picture of this aspect: [[Jim Hoggan]]’s ''Climate Cover-Up'', [[George Monbiot]]’s ''Heat: How to Stop the Planet Burning'' and [[Ross Gelbspan]]’s ''The Heat is On'' and ''Boiling Point''. England also said that there is little coverage about the millions of dollars which [[Exxon Mobil]] has put into funding groups actively involved in promoting [[climate change denial]] and doubt.<ref>England, Phil (September 10, 2010). [http://www.theecologist.org/reviews/books/592288/merchants_of_doubt.html Merchants of Doubt] ''[[The Ecologist]]''.</ref>

A review in ''[[The Economist]]'' calls this a powerful book which articulates the politics involved and the degree to which scientists have sometimes manufactured and exaggerated environmental uncertainties, but opines that the authors fail to fully explain how environmental action has still often proved possible despite countervailing factors.<ref>[http://www.economist.com/node/16374460 All guns blazing: A question of dodgy science], (June 17, 2010), ''[[The Economist]]''.</ref>

[[Robert N. Proctor]], who coined the term "[[agnotology]]" to describe the study of culturally induced ignorance or doubt, wrote in ''[[American Scientist]]'' that ''Merchants of Doubt'' is a detailed and artfully written book. He set it in the context of other books which cover the "history of manufactured ignorance":<ref name="Proctor">Proctor, Robert (September–October 2010). [http://www.americanscientist.org/bookshelf/pub/manufactured-ignorance Book Review: Manufactured Ignorance], ''[[American Scientist]]''.</ref> [[David Michaels (epidemiologist)|David Michaels]]’s ''[[Doubt is their Product]]'' (2008), [[Chris Mooney (journalist)|Chris Mooney]]’s ''[[The Republican War on Science]]'' (2009), [[David Rosner]] and Gerald Markowitz’s ''[[Deceit and Denial]]'' (2002), and his own book ''[[Cancer Wars]]'' (1995).<ref name="Proctor" />

Robin McKie in ''[[The Guardian]]'' states that Oreskes and Conway deserve considerable praise for exposing the influence of a small group of [[Cold War]] ideologues. Their tactic of spreading doubt has confused the public about a series of key scientific issues such as global warming, even though scientists have actually become more certain about their research results. McKie says that ''Merchants of Doubt'' includes detailed notes on all sources used, is carefully paced, and is "my runaway contender for best science book of the year".<ref name=Mckie8>McKie, Robin (August 8, 2010). [https://www.theguardian.com/books/2010/aug/08/merchants-of-doubt-oreskes-conway "Merchants of Doubt by Naomi Oreskes and Erik M Conway".] ''The Guardian''.</ref>

Sociologist [[Reiner Grundmann]]'s review in ''[[BioSocieties]]'' journal, acknowledges that the book is well researched and factually based, but criticizes the book as being written in a black and white manner whereas historians should write a more nuanced description. The book depicts special interests and contrarians misleading the public as being mainly responsible for stopping action on policy. He says this shows a lack of basic understanding of the political process and the mechanisms of [[knowledge policy]], because the authors assume that public policy would follow on from an understanding of the science. While the book provides ''all the (formal) hallmarks of science'', Grundmann sees it less as a scholarly work than a passionate attack and overall as a problematic book.<ref name="RG" />

William O’Keefe and Jeff Kueter from the [[George C. Marshall Institute]], which was founded by Seitz,<ref>{{cite web|last1=Begley|first1=Sharon|title=Global Warming Deniers: A Well-Funded Machine|url=http://www.newsweek.com/global-warming-deniers-well-funded-machine-99295|website=Newsweek|date=4 August 2007|quote=...a central cog in the denial machine: the George C. Marshall Institute, a conservative think tank.}}</ref> say that although ''Merchants of Doubt'' has the appearance of a scholarly work, it discredits and undermines the reputations of people who in their lifetime contributed greatly to the American nation. They say that it does this by questioning their integrity, impugning their character, and questioning their judgement.<ref>{{cite web | last=O’Keefe | first= William |last2= Kueter| first2=Jeff | date=June 2010 | url=http://marshall.org/wp-content/uploads/2011/06/OKeefe-and-Kueter-Clouding-the-Truth-A-Critique-of-Merchants-of-Doubt.pdf |title=Clouding the Truth: A Critique of Merchants of Doubt |publisher=[[George C. Marshall Institute]] |work=Policy Outlook | quote=Although cloaked in the appearance of scholarly work, the book constitutes an effort to discredit and undermine the reputations of three deceased scientists who contributed greatly to our nation... This book questions their integrity, impugns their character, and questions their judgment on the basis of little more than faulty logic and preconceived opinion}}</ref>

==Authors==
[[File:Naomi Oreskes 2nd European TA conference in Berlin 2015 (cropped to collar).JPG |thumb|right |[[Naomi Oreskes]] (2015), co-author of ''Merchants of Doubt''.]]
Naomi Oreskes is Professor of History and Science Studies at Harvard University. She has degrees in geological science and a [[Doctor of Philosophy|Ph.D.]] in [[Geological]] Research and the History of Science. Her work came to public attention in 2004 with the publication of "The Scientific Consensus on Climate Change," in ''Science'', in which she wrote that there was no significant disagreement in the scientific community about the reality of global warming from human causes.<ref name=collins>[http://www.marcovigevani.com/upload/london_2008/Collins_Literary_London_2008_Rights_List.pdf Collins Literary Agency Rights Guide/March 2008]</ref> Erik M. Conway is the historian at [[NASA]]'s [[Jet Propulsion Laboratory]] at the [[California Institute of Technology]] in [[Pasadena, California|Pasadena]].<ref name=collins/>

==Counterargument==
In 2011, aerospace engineer [[Robert Zubrin]], most famous for [[The Case for Mars]], penned a book length response, titled ''Merchants of Despair: Radical Environmentalists, Criminal Pseudo-Scientists, and the Fatal Cult of Antihumanism'', which traces the history of [[antihumanism]] over the last two centuries, from [[Thomas Malthus]] and the [[eugenics]] movement through to the [[Anti-nuclear movement|anti-nuclear]] and "alarmist" DDT and [[Global warming controversy|global warming]] campaigns. Zubrin argues that these movements, by means of pseudo-science, have caused deaths and by a number of methods, including that of statistical mis-treatments, have all attempted to gain oppressive political control through the restriction of human activities and freedom.<ref>[https://www.theobjectivestandard.com/issues/2012-fall/review-merchants-of-despair/
Review: Merchants of Despair, by Robert Zubrin
Ted Gray February 2, 2014 In ''The Objective Standard'' Fall 2012]</ref>

==See also==
* [[Climate change controversy]]
* [[Climate change policy of the United States]]
* ''[[Climate Capitalism]]''
* [[Fear, uncertainty and doubt]]
* [[Greenhouse Mafia]]
* [[Health effects of tobacco]]
* [[List of books about the politics of science]]
* [[List of scientists opposing the mainstream scientific assessment of global warming]] in contrast with [[Scientific opinion on climate change]]
* [[Media coverage of climate change]]
* [[Scientific consensus]]
* [[Tobacco control movement]]
* [[Tobacco politics]]

=== Other books on the same theme ===
* ''[[Doubt Is Their Product: How Industry's Assault on Science Threatens Your Health]]'' (2008) by [[David Michaels (epidemiologist)|David Michaels]]
* ''Climate Cover-Up: The Crusade to Deny Global Warming'' (2009) by James Hoggan and Richard Littlemore
* ''[[Climate Change Denial: Heads in the Sand]]'' (2011) by Haydn Washington and John Cook

==References==
{{Reflist|30em}}

==External links==
* {{official website|http://www.merchantsofdoubt.org/index.html}}
* [http://www.abc.net.au/rn/scienceshow/stories/2011/3101369.htm Merchants of Doubt], Public Lecture (2010), [[University of NSW]], ''The Science Show'', [[ABC Radio National]], January 8, 2011.

{{Portal bar|Global warming|Environment}}

[[Category:2010 books]]
[[Category:2010 in the environment]]
[[Category:21st-century history books]]
[[Category:History books about science]]
[[Category:History books about politics]]
[[Category:Climate change books]]
[[Category:Climate change skepticism and denial]]
[[Category:Environmental non-fiction books]]
[[Category:Political books]]
[[Category:Books about the politics of science]]
[[Category:Books adapted into films]]
[[Category:Professional ethics]]
[[Category:Doubt]]

Merchants of Doubt

2017-12-10T23:19:26Z

Boundarylayer: /* Counterargument */

{{About|the book|the film based on the book|Merchants of Doubt (film)}}
{{Use mdy dates|date=December 2015}}
{{good article}}
{{Infobox book
| name = Merchants of Doubt: How a Handful of Scientists Obscured the Truth on Issues from Tobacco Smoke to Global Warming
| image = Merchants of DOUBT.jpg
| image_size = 197px
| caption =
| author = [[Naomi Oreskes]], [[Erik M. Conway]]
| illustrator =
| cover_artist =
| country =
| series =
| subject = Scientists—Professional Ethics Science news—Moral and ethical aspects
| published = June 3, 2010 [[Bloomsbury Press]]
| media_type =
| pages = 355 pp.
| isbn = 978-1-59691-610-4
| oclc = 461631066
| dewey = 174.95
| congress = Q147 .O74 2010
}}

'''''Merchants of Doubt: How a Handful of Scientists Obscured the Truth on Issues from Tobacco Smoke to Global Warming''''' is a 2010 non-fiction book by American [[History of science|historians of science]] [[Naomi Oreskes]] and [[Erik M. Conway]]. It identifies parallels between the [[global warming controversy]] and earlier controversies over [[tobacco smoking]], [[acid rain]], [[DDT]], and the [[ozone depletion|hole in the ozone layer]]. Oreskes and Conway write that in each case "keeping the controversy alive" by spreading doubt and confusion after a scientific consensus had been reached, was the basic strategy of those opposing action.<ref name = stek>{{cite news |author=Steketee, Mike |title=Some sceptics make it a habit to be wrong |url=http://www.theaustralian.com.au/national-affairs/some-sceptics-make-it-a-habit-to-be-wrong/story-fn59niix-1225956414538 |newspaper=[[The Australian]] |date=November 20, 2010 }}</ref> In particular, they say that [[Fred Seitz]], [[Fred Singer]], and a few other [[contrarian]] scientists joined forces with conservative [[think tank]]s and private corporations to challenge the scientific consensus on many contemporary issues.<ref>{{cite book |first1=Naomi |last1=Oreskes |first2=Erik M. |last2=Conway |title=Merchants of Doubt: How a Handful of Scientists Obscured the Truth on Issues from Tobacco Smoke to Global Warming |url=https://books.google.com/books?id=fpMh3nh3JI0C&pg=PP4 |year=2010 |publisher=Bloomsbury Press |isbn=978-1-59691-610-4 |page=6 |ref=harv}} [http://www.merchantsofdoubt.org/index.html merchantsofdoubt.org]</ref>

The [[George C. Marshall Institute]] and Fred Singer, two of the subjects, have been critical of the book. Other reviewers have been more favorable. One reviewer said that ''Merchants of Doubt'' is exhaustively researched and documented, and may be one of the most important books of 2010. Another reviewer saw the book as his choice for best [[science book]] of the year.<ref name=Mckie8/> It was made into a film, ''[[Merchants of Doubt (film)|Merchants of Doubt]]'', directed by [[Robert Kenner]], released in 2014.<ref>{{cite web | url=http://sonyclassics.com/merchantsofdoubt/ | title=Merchants of Doubt | publisher=Sony Pictures Classics | accessdate=March 8, 2015}}</ref>

==Themes==
[[File:S Fred Singer 2011.jpg |thumb|right |[[Fred Singer]] (2011), a prominent opponent of greenhouse gas regulation.]]
Oreskes and Conway write that a handful of [[Conservatism in the United States|politically conservative]] scientists, with strong ties to particular industries, have "played a disproportionate role in debates about controversial questions".<ref name=pk/> The authors write that this has resulted in "deliberate obfuscation" of the issues which has had an influence on [[Public opinion on climate change|public opinion]] and [[Climate change policy of the United States|policy-making]].<ref name=pk>{{cite journal |author=Kitcher, Philip |authorlink=Philip Kitcher |title=The Climate Change Debates |journal=[[Science (journal)|Science]] |volume=328 |issue=5983 |pages=1231–2 |date=June 4, 2010 |doi=10.1126/science.1189312 |url=http://www.sciencemag.org/cgi/content/full/328/5983/1230-a }}</ref>

The book criticizes the so-called Merchants of Doubt, some predominantly American science key players, above all [[William Nierenberg|Bill Nierenberg]], [[Fred Seitz]], and [[Fred Singer]]. All three are physicists: Singer was a [[rocket scientist]], whereas Nierenberg and Seitz worked on the atomic bomb.<ref name=sb>{{cite news |author=Brown, Seth |title='Merchants of Doubt' delves into contrarian scientists |url=https://www.usatoday.com/money/books/reviews/2010-06-01-deathmerchants01_ST_N.htm |newspaper=[[USA Today]] |date=May 31, 2010 }}</ref> They have been active on topics like acid rain, tobacco smoking, global warming and pesticides. The book claims that these scientists have challenged and diluted the [[scientific consensus]] in the various fields, as of the [[dangers of smoking]], the effects of acid rain, the existence of the ozone hole, and the existence of [[anthropogenic climate change]].<ref name=pk/> Seitz and Singer have been involved with institutions such as [[The Heritage Foundation]], [[Competitive Enterprise Institute]] and [[George C. Marshall Institute]] in the United States. Funded by [[corporation]]s and conservative [[Foundation (United States law)|foundations]], these organizations have opposed many forms of [[Economic interventionism|state intervention]] or regulation of U.S. citizens. The book lists similar tactics in each case: "discredit the science, disseminate false information, spread confusion, and promote doubt".<ref name=rm/>

The book states that Seitz, Singer, Nierenberg and [[Robert Jastrow]] were all fiercely [[Anti-communism|anti-communist]] and they viewed government regulation as a step towards [[socialism]] and [[communism]]. The authors argue that, with the [[collapse of the Soviet Union]], they looked for another great threat to free market capitalism and found it in environmentalism. They feared that an over-reaction to environmental problems would lead to heavy-handed government intervention in the marketplace and intrusion into people's lives.<ref name=ocmerch/> Oreskes and Conway state that the longer the delay the worse these problems get, and the more likely it is that governments will need to take the draconian measures that conservatives and [[market fundamentalism|market fundamentalists]] most fear. They say that Seitz, Singer, Nierenberg and Jastrow denied the scientific evidence, contributed to a strategy of delay, and thereby helped to bring about the situation they most dreaded.<ref name=ocmerch>{{harvnb|Oreskes|Conway|2010|pp=248–255}}</ref> The authors have a strong doubt about the ability of the media to differentiate between false truth and the actual science in question; however, they stop short of endorsing censorship in the name of science.<ref name ="RG" /> The journalistic norm of balanced reporting has helped, according to the authors, to amplify the misleading messages of the contrarians. Oreskes and Conway state: "small numbers of people can have large, negative impacts, especially if they are organised, determined and have access to power".<ref name=rm>{{cite news |author=McKie, Robin |title=A dark ideology is driving those who deny climate change |url=https://www.theguardian.com/commentisfree/2010/aug/01/climate-change-robin-mckie |newspaper=The Guardian |date=August 1, 2010 }}</ref>

The main conclusion of the book is that there would have been more progress in policymaking, if not for the influence of the contrarian "experts", which tried on ideological reasons to undermine trust in the science base for regulation.<ref name="RG">{{cite journal|last1=Grundmann|first1=Reiner|title=Debunking sceptical propaganda|journal=BioSocieties|date=29 August 2013|volume=8|issue=3|pages=370–374|doi=10.1057/biosoc.2013.15|url=https://www.academia.edu/4754580/Debunking_skeptical_propaganda_Book_review_of_Oreskes_Conway_Merchants_of_Doubt}}</ref> Similar conclusions were already drawn, among others on [[Frederick Seitz]] and [[William Nierenberg]] in the book ''[[Requiem for a Species|Requiem for a Species: Why We Resist the Truth about Climate Change]]'' (2010) by Australian academic [[Clive Hamilton]].

==Reception==

[[Philip Kitcher]] in ''[[Science (magazine)|Science]]'' says that Naomi Oreskes and Erik Conway are "two outstanding historians".<ref name=pk/> He calls ''Merchants of Doubt'' a "fascinating and important study". Kitcher says that the apparently harsh claims against Nierenberg, Seitz, and Singer are "justified through a powerful dissection of the ways in which prominent climate scientists, such as [[Roger Revelle]] and [[Ben Santer]], were exploited or viciously attacked in the press".<ref name=pk/>

In ''[[The Christian Science Monitor]]'', Will Buchanan says that ''Merchants of Doubt'' is exhaustively researched and documented, and may be one of the most important books of 2010. Oreskes and Conway are seen to demonstrate that the doubt merchants are not "objective scientists" as the term is popularly understood. Instead, they are "science-speaking mercenaries" hired by corporations to process numbers to prove that the corporations’ products are safe and useful. Buchanan says they are salesmen, not scientists.<ref>Buchanan, Will (June 22, 2010). [http://www.csmonitor.com/Books/Book-Reviews/2010/0622/Merchants-of-Doubt Merchants of Doubt: How “scientific” misinformation campaigns sold untruths to consumers] ''The Christian Science Monitor''.</ref>

Bud Ward published a review of the book in ''The Yale Forum on Climate and the Media''. He wrote that Oreskes and Conway use a combination of thorough scholarly research combined with writing reminiscent of the best investigative journalism, to "unravel deep common links to past environmental and public health controversies".<ref name="Ward">Ward, Bud (July 8, 2010). [http://www.yaleclimatemediaforum.org/2010/07/merchants-of-doubt/ Reviews: Leaving No Doubt on Tobacco, Acid Rain, Climate Change], ''The Yale Forum on Climate and the Media''.</ref> In terms of climate science, the authors' leave "little doubt about their disdain for what they regard as the misuse and abuse of science by a small cabal of scientists they see as largely lacking in requisite climate science expertise".<ref name="Ward" />

Phil England writes in ''[[The Ecologist]]'' that the strength of the book is the rigour of the research and the detailed focus on key incidents. He said, however, that the climate change chapter is only 50 pages long, and recommends several other books for readers who want to get a broader picture of this aspect: [[Jim Hoggan]]’s ''Climate Cover-Up'', [[George Monbiot]]’s ''Heat: How to Stop the Planet Burning'' and [[Ross Gelbspan]]’s ''The Heat is On'' and ''Boiling Point''. England also said that there is little coverage about the millions of dollars which [[Exxon Mobil]] has put into funding groups actively involved in promoting [[climate change denial]] and doubt.<ref>England, Phil (September 10, 2010). [http://www.theecologist.org/reviews/books/592288/merchants_of_doubt.html Merchants of Doubt] ''[[The Ecologist]]''.</ref>

A review in ''[[The Economist]]'' calls this a powerful book which articulates the politics involved and the degree to which scientists have sometimes manufactured and exaggerated environmental uncertainties, but opines that the authors fail to fully explain how environmental action has still often proved possible despite countervailing factors.<ref>[http://www.economist.com/node/16374460 All guns blazing: A question of dodgy science], (June 17, 2010), ''[[The Economist]]''.</ref>

[[Robert N. Proctor]], who coined the term "[[agnotology]]" to describe the study of culturally induced ignorance or doubt, wrote in ''[[American Scientist]]'' that ''Merchants of Doubt'' is a detailed and artfully written book. He set it in the context of other books which cover the "history of manufactured ignorance":<ref name="Proctor">Proctor, Robert (September–October 2010). [http://www.americanscientist.org/bookshelf/pub/manufactured-ignorance Book Review: Manufactured Ignorance], ''[[American Scientist]]''.</ref> [[David Michaels (epidemiologist)|David Michaels]]’s ''[[Doubt is their Product]]'' (2008), [[Chris Mooney (journalist)|Chris Mooney]]’s ''[[The Republican War on Science]]'' (2009), [[David Rosner]] and Gerald Markowitz’s ''[[Deceit and Denial]]'' (2002), and his own book ''[[Cancer Wars]]'' (1995).<ref name="Proctor" />

Robin McKie in ''[[The Guardian]]'' states that Oreskes and Conway deserve considerable praise for exposing the influence of a small group of [[Cold War]] ideologues. Their tactic of spreading doubt has confused the public about a series of key scientific issues such as global warming, even though scientists have actually become more certain about their research results. McKie says that ''Merchants of Doubt'' includes detailed notes on all sources used, is carefully paced, and is "my runaway contender for best science book of the year".<ref name=Mckie8>McKie, Robin (August 8, 2010). [https://www.theguardian.com/books/2010/aug/08/merchants-of-doubt-oreskes-conway "Merchants of Doubt by Naomi Oreskes and Erik M Conway".] ''The Guardian''.</ref>

Sociologist [[Reiner Grundmann]]'s review in ''[[BioSocieties]]'' journal, acknowledges that the book is well researched and factually based, but criticizes the book as being written in a black and white manner whereas historians should write a more nuanced description. The book depicts special interests and contrarians misleading the public as being mainly responsible for stopping action on policy. He says this shows a lack of basic understanding of the political process and the mechanisms of [[knowledge policy]], because the authors assume that public policy would follow on from an understanding of the science. While the book provides ''all the (formal) hallmarks of science'', Grundmann sees it less as a scholarly work than a passionate attack and overall as a problematic book.<ref name="RG" />

William O’Keefe and Jeff Kueter from the [[George C. Marshall Institute]], which was founded by Seitz,<ref>{{cite web|last1=Begley|first1=Sharon|title=Global Warming Deniers: A Well-Funded Machine|url=http://www.newsweek.com/global-warming-deniers-well-funded-machine-99295|website=Newsweek|date=4 August 2007|quote=...a central cog in the denial machine: the George C. Marshall Institute, a conservative think tank.}}</ref> say that although ''Merchants of Doubt'' has the appearance of a scholarly work, it discredits and undermines the reputations of people who in their lifetime contributed greatly to the American nation. They say that it does this by questioning their integrity, impugning their character, and questioning their judgement.<ref>{{cite web | last=O’Keefe | first= William |last2= Kueter| first2=Jeff | date=June 2010 | url=http://marshall.org/wp-content/uploads/2011/06/OKeefe-and-Kueter-Clouding-the-Truth-A-Critique-of-Merchants-of-Doubt.pdf |title=Clouding the Truth: A Critique of Merchants of Doubt |publisher=[[George C. Marshall Institute]] |work=Policy Outlook | quote=Although cloaked in the appearance of scholarly work, the book constitutes an effort to discredit and undermine the reputations of three deceased scientists who contributed greatly to our nation... This book questions their integrity, impugns their character, and questions their judgment on the basis of little more than faulty logic and preconceived opinion}}</ref>

==Authors==
[[File:Naomi Oreskes 2nd European TA conference in Berlin 2015 (cropped to collar).JPG |thumb|right |[[Naomi Oreskes]] (2015), co-author of ''Merchants of Doubt''.]]
Naomi Oreskes is Professor of History and Science Studies at Harvard University. She has degrees in geological science and a [[Doctor of Philosophy|Ph.D.]] in [[Geological]] Research and the History of Science. Her work came to public attention in 2004 with the publication of "The Scientific Consensus on Climate Change," in ''Science'', in which she wrote that there was no significant disagreement in the scientific community about the reality of global warming from human causes.<ref name=collins>[http://www.marcovigevani.com/upload/london_2008/Collins_Literary_London_2008_Rights_List.pdf Collins Literary Agency Rights Guide/March 2008]</ref> Erik M. Conway is the historian at [[NASA]]'s [[Jet Propulsion Laboratory]] at the [[California Institute of Technology]] in [[Pasadena, California|Pasadena]].<ref name=collins/>

==Counterargument==
In 2011, aerospace engineer [[Robert Zubrin]], most famous for [[The Case for Mars]], penned a book length response, titled ''Merchants of Despair: Radical Environmentalists, Criminal Pseudo-Scientists, and the Fatal Cult of Antihumanism'', which traces the history of [[antihumanism]] over the last two centuries, from [[Thomas Malthus]] and the [[eugenics]] movement through to the [[Anti-nuclear movement|anti-nuclear]] and "alarmist" DDT and [[Global warming controversy|global warming]] campaigns. Zubrin argues that these movements, by means of pseudo-science, have caused deaths and by a number of methods, including that of statistical mis-treatments, have all attempted to gain oppressive political control through the restriction of human activities and freedom.<ref>[https://www.theobjectivestandard.com/issues/2012-fall/review-merchants-of-despair/
Review: Merchants of Despair, by Robert Zubrin
Ted Gray February 2, 2014 In ''The Objective Standard'' Fall 2012]</ref>

==See also==
* [[Climate change controversy]]
* [[Climate change policy of the United States]]
* ''[[Climate Capitalism]]''
* [[Fear, uncertainty and doubt]]
* [[Greenhouse Mafia]]
* [[Health effects of tobacco]]
* [[List of books about the politics of science]]
* [[List of scientists opposing the mainstream scientific assessment of global warming]] in contrast with [[Scientific opinion on climate change]]
* [[Media coverage of climate change]]
* [[Scientific consensus]]
* [[Tobacco control movement]]
* [[Tobacco politics]]

=== Other books on the same theme ===
* ''[[Doubt Is Their Product: How Industry's Assault on Science Threatens Your Health]]'' (2008) by [[David Michaels (epidemiologist)|David Michaels]]
* ''Climate Cover-Up: The Crusade to Deny Global Warming'' (2009) by James Hoggan and Richard Littlemore
* ''[[Climate Change Denial: Heads in the Sand]]'' (2011) by Haydn Washington and John Cook

==References==
{{Reflist|30em}}

==External links==
* {{official website|http://www.merchantsofdoubt.org/index.html}}
* [http://www.abc.net.au/rn/scienceshow/stories/2011/3101369.htm Merchants of Doubt], Public Lecture (2010), [[University of NSW]], ''The Science Show'', [[ABC Radio National]], January 8, 2011.

{{Portal bar|Global warming|Environment}}

[[Category:2010 books]]
[[Category:2010 in the environment]]
[[Category:21st-century history books]]
[[Category:History books about science]]
[[Category:History books about politics]]
[[Category:Climate change books]]
[[Category:Climate change skepticism and denial]]
[[Category:Environmental non-fiction books]]
[[Category:Political books]]
[[Category:Books about the politics of science]]
[[Category:Books adapted into films]]
[[Category:Professional ethics]]
[[Category:Doubt]]

Merchants of Doubt

2017-12-10T23:14:33Z

Boundarylayer: /* Counterargument */

{{About|the book|the film based on the book|Merchants of Doubt (film)}}
{{Use mdy dates|date=December 2015}}
{{good article}}
{{Infobox book
| name = Merchants of Doubt: How a Handful of Scientists Obscured the Truth on Issues from Tobacco Smoke to Global Warming
| image = Merchants of DOUBT.jpg
| image_size = 197px
| caption =
| author = [[Naomi Oreskes]], [[Erik M. Conway]]
| illustrator =
| cover_artist =
| country =
| series =
| subject = Scientists—Professional Ethics Science news—Moral and ethical aspects
| published = June 3, 2010 [[Bloomsbury Press]]
| media_type =
| pages = 355 pp.
| isbn = 978-1-59691-610-4
| oclc = 461631066
| dewey = 174.95
| congress = Q147 .O74 2010
}}

'''''Merchants of Doubt: How a Handful of Scientists Obscured the Truth on Issues from Tobacco Smoke to Global Warming''''' is a 2010 non-fiction book by American [[History of science|historians of science]] [[Naomi Oreskes]] and [[Erik M. Conway]]. It identifies parallels between the [[global warming controversy]] and earlier controversies over [[tobacco smoking]], [[acid rain]], [[DDT]], and the [[ozone depletion|hole in the ozone layer]]. Oreskes and Conway write that in each case "keeping the controversy alive" by spreading doubt and confusion after a scientific consensus had been reached, was the basic strategy of those opposing action.<ref name = stek>{{cite news |author=Steketee, Mike |title=Some sceptics make it a habit to be wrong |url=http://www.theaustralian.com.au/national-affairs/some-sceptics-make-it-a-habit-to-be-wrong/story-fn59niix-1225956414538 |newspaper=[[The Australian]] |date=November 20, 2010 }}</ref> In particular, they say that [[Fred Seitz]], [[Fred Singer]], and a few other [[contrarian]] scientists joined forces with conservative [[think tank]]s and private corporations to challenge the scientific consensus on many contemporary issues.<ref>{{cite book |first1=Naomi |last1=Oreskes |first2=Erik M. |last2=Conway |title=Merchants of Doubt: How a Handful of Scientists Obscured the Truth on Issues from Tobacco Smoke to Global Warming |url=https://books.google.com/books?id=fpMh3nh3JI0C&pg=PP4 |year=2010 |publisher=Bloomsbury Press |isbn=978-1-59691-610-4 |page=6 |ref=harv}} [http://www.merchantsofdoubt.org/index.html merchantsofdoubt.org]</ref>

The [[George C. Marshall Institute]] and Fred Singer, two of the subjects, have been critical of the book. Other reviewers have been more favorable. One reviewer said that ''Merchants of Doubt'' is exhaustively researched and documented, and may be one of the most important books of 2010. Another reviewer saw the book as his choice for best [[science book]] of the year.<ref name=Mckie8/> It was made into a film, ''[[Merchants of Doubt (film)|Merchants of Doubt]]'', directed by [[Robert Kenner]], released in 2014.<ref>{{cite web | url=http://sonyclassics.com/merchantsofdoubt/ | title=Merchants of Doubt | publisher=Sony Pictures Classics | accessdate=March 8, 2015}}</ref>

==Themes==
[[File:S Fred Singer 2011.jpg |thumb|right |[[Fred Singer]] (2011), a prominent opponent of greenhouse gas regulation.]]
Oreskes and Conway write that a handful of [[Conservatism in the United States|politically conservative]] scientists, with strong ties to particular industries, have "played a disproportionate role in debates about controversial questions".<ref name=pk/> The authors write that this has resulted in "deliberate obfuscation" of the issues which has had an influence on [[Public opinion on climate change|public opinion]] and [[Climate change policy of the United States|policy-making]].<ref name=pk>{{cite journal |author=Kitcher, Philip |authorlink=Philip Kitcher |title=The Climate Change Debates |journal=[[Science (journal)|Science]] |volume=328 |issue=5983 |pages=1231–2 |date=June 4, 2010 |doi=10.1126/science.1189312 |url=http://www.sciencemag.org/cgi/content/full/328/5983/1230-a }}</ref>

The book criticizes the so-called Merchants of Doubt, some predominantly American science key players, above all [[William Nierenberg|Bill Nierenberg]], [[Fred Seitz]], and [[Fred Singer]]. All three are physicists: Singer was a [[rocket scientist]], whereas Nierenberg and Seitz worked on the atomic bomb.<ref name=sb>{{cite news |author=Brown, Seth |title='Merchants of Doubt' delves into contrarian scientists |url=https://www.usatoday.com/money/books/reviews/2010-06-01-deathmerchants01_ST_N.htm |newspaper=[[USA Today]] |date=May 31, 2010 }}</ref> They have been active on topics like acid rain, tobacco smoking, global warming and pesticides. The book claims that these scientists have challenged and diluted the [[scientific consensus]] in the various fields, as of the [[dangers of smoking]], the effects of acid rain, the existence of the ozone hole, and the existence of [[anthropogenic climate change]].<ref name=pk/> Seitz and Singer have been involved with institutions such as [[The Heritage Foundation]], [[Competitive Enterprise Institute]] and [[George C. Marshall Institute]] in the United States. Funded by [[corporation]]s and conservative [[Foundation (United States law)|foundations]], these organizations have opposed many forms of [[Economic interventionism|state intervention]] or regulation of U.S. citizens. The book lists similar tactics in each case: "discredit the science, disseminate false information, spread confusion, and promote doubt".<ref name=rm/>

The book states that Seitz, Singer, Nierenberg and [[Robert Jastrow]] were all fiercely [[Anti-communism|anti-communist]] and they viewed government regulation as a step towards [[socialism]] and [[communism]]. The authors argue that, with the [[collapse of the Soviet Union]], they looked for another great threat to free market capitalism and found it in environmentalism. They feared that an over-reaction to environmental problems would lead to heavy-handed government intervention in the marketplace and intrusion into people's lives.<ref name=ocmerch/> Oreskes and Conway state that the longer the delay the worse these problems get, and the more likely it is that governments will need to take the draconian measures that conservatives and [[market fundamentalism|market fundamentalists]] most fear. They say that Seitz, Singer, Nierenberg and Jastrow denied the scientific evidence, contributed to a strategy of delay, and thereby helped to bring about the situation they most dreaded.<ref name=ocmerch>{{harvnb|Oreskes|Conway|2010|pp=248–255}}</ref> The authors have a strong doubt about the ability of the media to differentiate between false truth and the actual science in question; however, they stop short of endorsing censorship in the name of science.<ref name ="RG" /> The journalistic norm of balanced reporting has helped, according to the authors, to amplify the misleading messages of the contrarians. Oreskes and Conway state: "small numbers of people can have large, negative impacts, especially if they are organised, determined and have access to power".<ref name=rm>{{cite news |author=McKie, Robin |title=A dark ideology is driving those who deny climate change |url=https://www.theguardian.com/commentisfree/2010/aug/01/climate-change-robin-mckie |newspaper=The Guardian |date=August 1, 2010 }}</ref>

The main conclusion of the book is that there would have been more progress in policymaking, if not for the influence of the contrarian "experts", which tried on ideological reasons to undermine trust in the science base for regulation.<ref name="RG">{{cite journal|last1=Grundmann|first1=Reiner|title=Debunking sceptical propaganda|journal=BioSocieties|date=29 August 2013|volume=8|issue=3|pages=370–374|doi=10.1057/biosoc.2013.15|url=https://www.academia.edu/4754580/Debunking_skeptical_propaganda_Book_review_of_Oreskes_Conway_Merchants_of_Doubt}}</ref> Similar conclusions were already drawn, among others on [[Frederick Seitz]] and [[William Nierenberg]] in the book ''[[Requiem for a Species|Requiem for a Species: Why We Resist the Truth about Climate Change]]'' (2010) by Australian academic [[Clive Hamilton]].

==Reception==

[[Philip Kitcher]] in ''[[Science (magazine)|Science]]'' says that Naomi Oreskes and Erik Conway are "two outstanding historians".<ref name=pk/> He calls ''Merchants of Doubt'' a "fascinating and important study". Kitcher says that the apparently harsh claims against Nierenberg, Seitz, and Singer are "justified through a powerful dissection of the ways in which prominent climate scientists, such as [[Roger Revelle]] and [[Ben Santer]], were exploited or viciously attacked in the press".<ref name=pk/>

In ''[[The Christian Science Monitor]]'', Will Buchanan says that ''Merchants of Doubt'' is exhaustively researched and documented, and may be one of the most important books of 2010. Oreskes and Conway are seen to demonstrate that the doubt merchants are not "objective scientists" as the term is popularly understood. Instead, they are "science-speaking mercenaries" hired by corporations to process numbers to prove that the corporations’ products are safe and useful. Buchanan says they are salesmen, not scientists.<ref>Buchanan, Will (June 22, 2010). [http://www.csmonitor.com/Books/Book-Reviews/2010/0622/Merchants-of-Doubt Merchants of Doubt: How “scientific” misinformation campaigns sold untruths to consumers] ''The Christian Science Monitor''.</ref>

Bud Ward published a review of the book in ''The Yale Forum on Climate and the Media''. He wrote that Oreskes and Conway use a combination of thorough scholarly research combined with writing reminiscent of the best investigative journalism, to "unravel deep common links to past environmental and public health controversies".<ref name="Ward">Ward, Bud (July 8, 2010). [http://www.yaleclimatemediaforum.org/2010/07/merchants-of-doubt/ Reviews: Leaving No Doubt on Tobacco, Acid Rain, Climate Change], ''The Yale Forum on Climate and the Media''.</ref> In terms of climate science, the authors' leave "little doubt about their disdain for what they regard as the misuse and abuse of science by a small cabal of scientists they see as largely lacking in requisite climate science expertise".<ref name="Ward" />

Phil England writes in ''[[The Ecologist]]'' that the strength of the book is the rigour of the research and the detailed focus on key incidents. He said, however, that the climate change chapter is only 50 pages long, and recommends several other books for readers who want to get a broader picture of this aspect: [[Jim Hoggan]]’s ''Climate Cover-Up'', [[George Monbiot]]’s ''Heat: How to Stop the Planet Burning'' and [[Ross Gelbspan]]’s ''The Heat is On'' and ''Boiling Point''. England also said that there is little coverage about the millions of dollars which [[Exxon Mobil]] has put into funding groups actively involved in promoting [[climate change denial]] and doubt.<ref>England, Phil (September 10, 2010). [http://www.theecologist.org/reviews/books/592288/merchants_of_doubt.html Merchants of Doubt] ''[[The Ecologist]]''.</ref>

A review in ''[[The Economist]]'' calls this a powerful book which articulates the politics involved and the degree to which scientists have sometimes manufactured and exaggerated environmental uncertainties, but opines that the authors fail to fully explain how environmental action has still often proved possible despite countervailing factors.<ref>[http://www.economist.com/node/16374460 All guns blazing: A question of dodgy science], (June 17, 2010), ''[[The Economist]]''.</ref>

[[Robert N. Proctor]], who coined the term "[[agnotology]]" to describe the study of culturally induced ignorance or doubt, wrote in ''[[American Scientist]]'' that ''Merchants of Doubt'' is a detailed and artfully written book. He set it in the context of other books which cover the "history of manufactured ignorance":<ref name="Proctor">Proctor, Robert (September–October 2010). [http://www.americanscientist.org/bookshelf/pub/manufactured-ignorance Book Review: Manufactured Ignorance], ''[[American Scientist]]''.</ref> [[David Michaels (epidemiologist)|David Michaels]]’s ''[[Doubt is their Product]]'' (2008), [[Chris Mooney (journalist)|Chris Mooney]]’s ''[[The Republican War on Science]]'' (2009), [[David Rosner]] and Gerald Markowitz’s ''[[Deceit and Denial]]'' (2002), and his own book ''[[Cancer Wars]]'' (1995).<ref name="Proctor" />

Robin McKie in ''[[The Guardian]]'' states that Oreskes and Conway deserve considerable praise for exposing the influence of a small group of [[Cold War]] ideologues. Their tactic of spreading doubt has confused the public about a series of key scientific issues such as global warming, even though scientists have actually become more certain about their research results. McKie says that ''Merchants of Doubt'' includes detailed notes on all sources used, is carefully paced, and is "my runaway contender for best science book of the year".<ref name=Mckie8>McKie, Robin (August 8, 2010). [https://www.theguardian.com/books/2010/aug/08/merchants-of-doubt-oreskes-conway "Merchants of Doubt by Naomi Oreskes and Erik M Conway".] ''The Guardian''.</ref>

Sociologist [[Reiner Grundmann]]'s review in ''[[BioSocieties]]'' journal, acknowledges that the book is well researched and factually based, but criticizes the book as being written in a black and white manner whereas historians should write a more nuanced description. The book depicts special interests and contrarians misleading the public as being mainly responsible for stopping action on policy. He says this shows a lack of basic understanding of the political process and the mechanisms of [[knowledge policy]], because the authors assume that public policy would follow on from an understanding of the science. While the book provides ''all the (formal) hallmarks of science'', Grundmann sees it less as a scholarly work than a passionate attack and overall as a problematic book.<ref name="RG" />

William O’Keefe and Jeff Kueter from the [[George C. Marshall Institute]], which was founded by Seitz,<ref>{{cite web|last1=Begley|first1=Sharon|title=Global Warming Deniers: A Well-Funded Machine|url=http://www.newsweek.com/global-warming-deniers-well-funded-machine-99295|website=Newsweek|date=4 August 2007|quote=...a central cog in the denial machine: the George C. Marshall Institute, a conservative think tank.}}</ref> say that although ''Merchants of Doubt'' has the appearance of a scholarly work, it discredits and undermines the reputations of people who in their lifetime contributed greatly to the American nation. They say that it does this by questioning their integrity, impugning their character, and questioning their judgement.<ref>{{cite web | last=O’Keefe | first= William |last2= Kueter| first2=Jeff | date=June 2010 | url=http://marshall.org/wp-content/uploads/2011/06/OKeefe-and-Kueter-Clouding-the-Truth-A-Critique-of-Merchants-of-Doubt.pdf |title=Clouding the Truth: A Critique of Merchants of Doubt |publisher=[[George C. Marshall Institute]] |work=Policy Outlook | quote=Although cloaked in the appearance of scholarly work, the book constitutes an effort to discredit and undermine the reputations of three deceased scientists who contributed greatly to our nation... This book questions their integrity, impugns their character, and questions their judgment on the basis of little more than faulty logic and preconceived opinion}}</ref>

==Authors==
[[File:Naomi Oreskes 2nd European TA conference in Berlin 2015 (cropped to collar).JPG |thumb|right |[[Naomi Oreskes]] (2015), co-author of ''Merchants of Doubt''.]]
Naomi Oreskes is Professor of History and Science Studies at Harvard University. She has degrees in geological science and a [[Doctor of Philosophy|Ph.D.]] in [[Geological]] Research and the History of Science. Her work came to public attention in 2004 with the publication of "The Scientific Consensus on Climate Change," in ''Science'', in which she wrote that there was no significant disagreement in the scientific community about the reality of global warming from human causes.<ref name=collins>[http://www.marcovigevani.com/upload/london_2008/Collins_Literary_London_2008_Rights_List.pdf Collins Literary Agency Rights Guide/March 2008]</ref> Erik M. Conway is the historian at [[NASA]]'s [[Jet Propulsion Laboratory]] at the [[California Institute of Technology]] in [[Pasadena, California|Pasadena]].<ref name=collins/>

==Counterargument==
In 2011, aerospace engineer [[Robert Zubrin]], most famous for [[The Case for Mars]], penned a book length response, titled ''Merchants of Despair: Radical Environmentalists, Criminal Pseudo-Scientists, and the Fatal Cult of Antihumanism'', which traces the history of [[antihumanism]] over the last two centuries, from [[Thomas Malthus]] and the [[eugenics]] movement through to the [[Anti-nuclear movement|anti-nuclear]] and "alarmist" DDT and [[Global warming controversy|global warming]] campaigns. Zubrin argues that these movements have caused deaths and by a number of means, including that of statistical mis-treatments, have all attempted to gain oppressive political control through the restriction of human activities and freedom.<ref>[https://www.theobjectivestandard.com/issues/2012-fall/review-merchants-of-despair/
Review: Merchants of Despair, by Robert Zubrin
Ted Gray February 2, 2014 In ''The Objective Standard'' Fall 2012]</ref>

==See also==
* [[Climate change controversy]]
* [[Climate change policy of the United States]]
* ''[[Climate Capitalism]]''
* [[Fear, uncertainty and doubt]]
* [[Greenhouse Mafia]]
* [[Health effects of tobacco]]
* [[List of books about the politics of science]]
* [[List of scientists opposing the mainstream scientific assessment of global warming]] in contrast with [[Scientific opinion on climate change]]
* [[Media coverage of climate change]]
* [[Scientific consensus]]
* [[Tobacco control movement]]
* [[Tobacco politics]]

=== Other books on the same theme ===
* ''[[Doubt Is Their Product: How Industry's Assault on Science Threatens Your Health]]'' (2008) by [[David Michaels (epidemiologist)|David Michaels]]
* ''Climate Cover-Up: The Crusade to Deny Global Warming'' (2009) by James Hoggan and Richard Littlemore
* ''[[Climate Change Denial: Heads in the Sand]]'' (2011) by Haydn Washington and John Cook

==References==
{{Reflist|30em}}

==External links==
* {{official website|http://www.merchantsofdoubt.org/index.html}}
* [http://www.abc.net.au/rn/scienceshow/stories/2011/3101369.htm Merchants of Doubt], Public Lecture (2010), [[University of NSW]], ''The Science Show'', [[ABC Radio National]], January 8, 2011.

{{Portal bar|Global warming|Environment}}

[[Category:2010 books]]
[[Category:2010 in the environment]]
[[Category:21st-century history books]]
[[Category:History books about science]]
[[Category:History books about politics]]
[[Category:Climate change books]]
[[Category:Climate change skepticism and denial]]
[[Category:Environmental non-fiction books]]
[[Category:Political books]]
[[Category:Books about the politics of science]]
[[Category:Books adapted into films]]
[[Category:Professional ethics]]
[[Category:Doubt]]

Merchants of Doubt

2017-12-10T23:11:32Z

Boundarylayer: /* Counterargument */

{{About|the book|the film based on the book|Merchants of Doubt (film)}}
{{Use mdy dates|date=December 2015}}
{{good article}}
{{Infobox book
| name = Merchants of Doubt: How a Handful of Scientists Obscured the Truth on Issues from Tobacco Smoke to Global Warming
| image = Merchants of DOUBT.jpg
| image_size = 197px
| caption =
| author = [[Naomi Oreskes]], [[Erik M. Conway]]
| illustrator =
| cover_artist =
| country =
| series =
| subject = Scientists—Professional Ethics Science news—Moral and ethical aspects
| published = June 3, 2010 [[Bloomsbury Press]]
| media_type =
| pages = 355 pp.
| isbn = 978-1-59691-610-4
| oclc = 461631066
| dewey = 174.95
| congress = Q147 .O74 2010
}}

'''''Merchants of Doubt: How a Handful of Scientists Obscured the Truth on Issues from Tobacco Smoke to Global Warming''''' is a 2010 non-fiction book by American [[History of science|historians of science]] [[Naomi Oreskes]] and [[Erik M. Conway]]. It identifies parallels between the [[global warming controversy]] and earlier controversies over [[tobacco smoking]], [[acid rain]], [[DDT]], and the [[ozone depletion|hole in the ozone layer]]. Oreskes and Conway write that in each case "keeping the controversy alive" by spreading doubt and confusion after a scientific consensus had been reached, was the basic strategy of those opposing action.<ref name = stek>{{cite news |author=Steketee, Mike |title=Some sceptics make it a habit to be wrong |url=http://www.theaustralian.com.au/national-affairs/some-sceptics-make-it-a-habit-to-be-wrong/story-fn59niix-1225956414538 |newspaper=[[The Australian]] |date=November 20, 2010 }}</ref> In particular, they say that [[Fred Seitz]], [[Fred Singer]], and a few other [[contrarian]] scientists joined forces with conservative [[think tank]]s and private corporations to challenge the scientific consensus on many contemporary issues.<ref>{{cite book |first1=Naomi |last1=Oreskes |first2=Erik M. |last2=Conway |title=Merchants of Doubt: How a Handful of Scientists Obscured the Truth on Issues from Tobacco Smoke to Global Warming |url=https://books.google.com/books?id=fpMh3nh3JI0C&pg=PP4 |year=2010 |publisher=Bloomsbury Press |isbn=978-1-59691-610-4 |page=6 |ref=harv}} [http://www.merchantsofdoubt.org/index.html merchantsofdoubt.org]</ref>

The [[George C. Marshall Institute]] and Fred Singer, two of the subjects, have been critical of the book. Other reviewers have been more favorable. One reviewer said that ''Merchants of Doubt'' is exhaustively researched and documented, and may be one of the most important books of 2010. Another reviewer saw the book as his choice for best [[science book]] of the year.<ref name=Mckie8/> It was made into a film, ''[[Merchants of Doubt (film)|Merchants of Doubt]]'', directed by [[Robert Kenner]], released in 2014.<ref>{{cite web | url=http://sonyclassics.com/merchantsofdoubt/ | title=Merchants of Doubt | publisher=Sony Pictures Classics | accessdate=March 8, 2015}}</ref>

==Themes==
[[File:S Fred Singer 2011.jpg |thumb|right |[[Fred Singer]] (2011), a prominent opponent of greenhouse gas regulation.]]
Oreskes and Conway write that a handful of [[Conservatism in the United States|politically conservative]] scientists, with strong ties to particular industries, have "played a disproportionate role in debates about controversial questions".<ref name=pk/> The authors write that this has resulted in "deliberate obfuscation" of the issues which has had an influence on [[Public opinion on climate change|public opinion]] and [[Climate change policy of the United States|policy-making]].<ref name=pk>{{cite journal |author=Kitcher, Philip |authorlink=Philip Kitcher |title=The Climate Change Debates |journal=[[Science (journal)|Science]] |volume=328 |issue=5983 |pages=1231–2 |date=June 4, 2010 |doi=10.1126/science.1189312 |url=http://www.sciencemag.org/cgi/content/full/328/5983/1230-a }}</ref>

The book criticizes the so-called Merchants of Doubt, some predominantly American science key players, above all [[William Nierenberg|Bill Nierenberg]], [[Fred Seitz]], and [[Fred Singer]]. All three are physicists: Singer was a [[rocket scientist]], whereas Nierenberg and Seitz worked on the atomic bomb.<ref name=sb>{{cite news |author=Brown, Seth |title='Merchants of Doubt' delves into contrarian scientists |url=https://www.usatoday.com/money/books/reviews/2010-06-01-deathmerchants01_ST_N.htm |newspaper=[[USA Today]] |date=May 31, 2010 }}</ref> They have been active on topics like acid rain, tobacco smoking, global warming and pesticides. The book claims that these scientists have challenged and diluted the [[scientific consensus]] in the various fields, as of the [[dangers of smoking]], the effects of acid rain, the existence of the ozone hole, and the existence of [[anthropogenic climate change]].<ref name=pk/> Seitz and Singer have been involved with institutions such as [[The Heritage Foundation]], [[Competitive Enterprise Institute]] and [[George C. Marshall Institute]] in the United States. Funded by [[corporation]]s and conservative [[Foundation (United States law)|foundations]], these organizations have opposed many forms of [[Economic interventionism|state intervention]] or regulation of U.S. citizens. The book lists similar tactics in each case: "discredit the science, disseminate false information, spread confusion, and promote doubt".<ref name=rm/>

The book states that Seitz, Singer, Nierenberg and [[Robert Jastrow]] were all fiercely [[Anti-communism|anti-communist]] and they viewed government regulation as a step towards [[socialism]] and [[communism]]. The authors argue that, with the [[collapse of the Soviet Union]], they looked for another great threat to free market capitalism and found it in environmentalism. They feared that an over-reaction to environmental problems would lead to heavy-handed government intervention in the marketplace and intrusion into people's lives.<ref name=ocmerch/> Oreskes and Conway state that the longer the delay the worse these problems get, and the more likely it is that governments will need to take the draconian measures that conservatives and [[market fundamentalism|market fundamentalists]] most fear. They say that Seitz, Singer, Nierenberg and Jastrow denied the scientific evidence, contributed to a strategy of delay, and thereby helped to bring about the situation they most dreaded.<ref name=ocmerch>{{harvnb|Oreskes|Conway|2010|pp=248–255}}</ref> The authors have a strong doubt about the ability of the media to differentiate between false truth and the actual science in question; however, they stop short of endorsing censorship in the name of science.<ref name ="RG" /> The journalistic norm of balanced reporting has helped, according to the authors, to amplify the misleading messages of the contrarians. Oreskes and Conway state: "small numbers of people can have large, negative impacts, especially if they are organised, determined and have access to power".<ref name=rm>{{cite news |author=McKie, Robin |title=A dark ideology is driving those who deny climate change |url=https://www.theguardian.com/commentisfree/2010/aug/01/climate-change-robin-mckie |newspaper=The Guardian |date=August 1, 2010 }}</ref>

The main conclusion of the book is that there would have been more progress in policymaking, if not for the influence of the contrarian "experts", which tried on ideological reasons to undermine trust in the science base for regulation.<ref name="RG">{{cite journal|last1=Grundmann|first1=Reiner|title=Debunking sceptical propaganda|journal=BioSocieties|date=29 August 2013|volume=8|issue=3|pages=370–374|doi=10.1057/biosoc.2013.15|url=https://www.academia.edu/4754580/Debunking_skeptical_propaganda_Book_review_of_Oreskes_Conway_Merchants_of_Doubt}}</ref> Similar conclusions were already drawn, among others on [[Frederick Seitz]] and [[William Nierenberg]] in the book ''[[Requiem for a Species|Requiem for a Species: Why We Resist the Truth about Climate Change]]'' (2010) by Australian academic [[Clive Hamilton]].

==Reception==

[[Philip Kitcher]] in ''[[Science (magazine)|Science]]'' says that Naomi Oreskes and Erik Conway are "two outstanding historians".<ref name=pk/> He calls ''Merchants of Doubt'' a "fascinating and important study". Kitcher says that the apparently harsh claims against Nierenberg, Seitz, and Singer are "justified through a powerful dissection of the ways in which prominent climate scientists, such as [[Roger Revelle]] and [[Ben Santer]], were exploited or viciously attacked in the press".<ref name=pk/>

In ''[[The Christian Science Monitor]]'', Will Buchanan says that ''Merchants of Doubt'' is exhaustively researched and documented, and may be one of the most important books of 2010. Oreskes and Conway are seen to demonstrate that the doubt merchants are not "objective scientists" as the term is popularly understood. Instead, they are "science-speaking mercenaries" hired by corporations to process numbers to prove that the corporations’ products are safe and useful. Buchanan says they are salesmen, not scientists.<ref>Buchanan, Will (June 22, 2010). [http://www.csmonitor.com/Books/Book-Reviews/2010/0622/Merchants-of-Doubt Merchants of Doubt: How “scientific” misinformation campaigns sold untruths to consumers] ''The Christian Science Monitor''.</ref>

Bud Ward published a review of the book in ''The Yale Forum on Climate and the Media''. He wrote that Oreskes and Conway use a combination of thorough scholarly research combined with writing reminiscent of the best investigative journalism, to "unravel deep common links to past environmental and public health controversies".<ref name="Ward">Ward, Bud (July 8, 2010). [http://www.yaleclimatemediaforum.org/2010/07/merchants-of-doubt/ Reviews: Leaving No Doubt on Tobacco, Acid Rain, Climate Change], ''The Yale Forum on Climate and the Media''.</ref> In terms of climate science, the authors' leave "little doubt about their disdain for what they regard as the misuse and abuse of science by a small cabal of scientists they see as largely lacking in requisite climate science expertise".<ref name="Ward" />

Phil England writes in ''[[The Ecologist]]'' that the strength of the book is the rigour of the research and the detailed focus on key incidents. He said, however, that the climate change chapter is only 50 pages long, and recommends several other books for readers who want to get a broader picture of this aspect: [[Jim Hoggan]]’s ''Climate Cover-Up'', [[George Monbiot]]’s ''Heat: How to Stop the Planet Burning'' and [[Ross Gelbspan]]’s ''The Heat is On'' and ''Boiling Point''. England also said that there is little coverage about the millions of dollars which [[Exxon Mobil]] has put into funding groups actively involved in promoting [[climate change denial]] and doubt.<ref>England, Phil (September 10, 2010). [http://www.theecologist.org/reviews/books/592288/merchants_of_doubt.html Merchants of Doubt] ''[[The Ecologist]]''.</ref>

A review in ''[[The Economist]]'' calls this a powerful book which articulates the politics involved and the degree to which scientists have sometimes manufactured and exaggerated environmental uncertainties, but opines that the authors fail to fully explain how environmental action has still often proved possible despite countervailing factors.<ref>[http://www.economist.com/node/16374460 All guns blazing: A question of dodgy science], (June 17, 2010), ''[[The Economist]]''.</ref>

[[Robert N. Proctor]], who coined the term "[[agnotology]]" to describe the study of culturally induced ignorance or doubt, wrote in ''[[American Scientist]]'' that ''Merchants of Doubt'' is a detailed and artfully written book. He set it in the context of other books which cover the "history of manufactured ignorance":<ref name="Proctor">Proctor, Robert (September–October 2010). [http://www.americanscientist.org/bookshelf/pub/manufactured-ignorance Book Review: Manufactured Ignorance], ''[[American Scientist]]''.</ref> [[David Michaels (epidemiologist)|David Michaels]]’s ''[[Doubt is their Product]]'' (2008), [[Chris Mooney (journalist)|Chris Mooney]]’s ''[[The Republican War on Science]]'' (2009), [[David Rosner]] and Gerald Markowitz’s ''[[Deceit and Denial]]'' (2002), and his own book ''[[Cancer Wars]]'' (1995).<ref name="Proctor" />

Robin McKie in ''[[The Guardian]]'' states that Oreskes and Conway deserve considerable praise for exposing the influence of a small group of [[Cold War]] ideologues. Their tactic of spreading doubt has confused the public about a series of key scientific issues such as global warming, even though scientists have actually become more certain about their research results. McKie says that ''Merchants of Doubt'' includes detailed notes on all sources used, is carefully paced, and is "my runaway contender for best science book of the year".<ref name=Mckie8>McKie, Robin (August 8, 2010). [https://www.theguardian.com/books/2010/aug/08/merchants-of-doubt-oreskes-conway "Merchants of Doubt by Naomi Oreskes and Erik M Conway".] ''The Guardian''.</ref>

Sociologist [[Reiner Grundmann]]'s review in ''[[BioSocieties]]'' journal, acknowledges that the book is well researched and factually based, but criticizes the book as being written in a black and white manner whereas historians should write a more nuanced description. The book depicts special interests and contrarians misleading the public as being mainly responsible for stopping action on policy. He says this shows a lack of basic understanding of the political process and the mechanisms of [[knowledge policy]], because the authors assume that public policy would follow on from an understanding of the science. While the book provides ''all the (formal) hallmarks of science'', Grundmann sees it less as a scholarly work than a passionate attack and overall as a problematic book.<ref name="RG" />

William O’Keefe and Jeff Kueter from the [[George C. Marshall Institute]], which was founded by Seitz,<ref>{{cite web|last1=Begley|first1=Sharon|title=Global Warming Deniers: A Well-Funded Machine|url=http://www.newsweek.com/global-warming-deniers-well-funded-machine-99295|website=Newsweek|date=4 August 2007|quote=...a central cog in the denial machine: the George C. Marshall Institute, a conservative think tank.}}</ref> say that although ''Merchants of Doubt'' has the appearance of a scholarly work, it discredits and undermines the reputations of people who in their lifetime contributed greatly to the American nation. They say that it does this by questioning their integrity, impugning their character, and questioning their judgement.<ref>{{cite web | last=O’Keefe | first= William |last2= Kueter| first2=Jeff | date=June 2010 | url=http://marshall.org/wp-content/uploads/2011/06/OKeefe-and-Kueter-Clouding-the-Truth-A-Critique-of-Merchants-of-Doubt.pdf |title=Clouding the Truth: A Critique of Merchants of Doubt |publisher=[[George C. Marshall Institute]] |work=Policy Outlook | quote=Although cloaked in the appearance of scholarly work, the book constitutes an effort to discredit and undermine the reputations of three deceased scientists who contributed greatly to our nation... This book questions their integrity, impugns their character, and questions their judgment on the basis of little more than faulty logic and preconceived opinion}}</ref>

==Authors==
[[File:Naomi Oreskes 2nd European TA conference in Berlin 2015 (cropped to collar).JPG |thumb|right |[[Naomi Oreskes]] (2015), co-author of ''Merchants of Doubt''.]]
Naomi Oreskes is Professor of History and Science Studies at Harvard University. She has degrees in geological science and a [[Doctor of Philosophy|Ph.D.]] in [[Geological]] Research and the History of Science. Her work came to public attention in 2004 with the publication of "The Scientific Consensus on Climate Change," in ''Science'', in which she wrote that there was no significant disagreement in the scientific community about the reality of global warming from human causes.<ref name=collins>[http://www.marcovigevani.com/upload/london_2008/Collins_Literary_London_2008_Rights_List.pdf Collins Literary Agency Rights Guide/March 2008]</ref> Erik M. Conway is the historian at [[NASA]]'s [[Jet Propulsion Laboratory]] at the [[California Institute of Technology]] in [[Pasadena, California|Pasadena]].<ref name=collins/>

==Counterargument==
In 2011, aerospace engineer [[Robert Zubrin]], most famous for [[The Case for Mars]], penned a book length response, titled ''Merchants of Despair: Radical Environmentalists, Criminal Pseudo-Scientists, and the Fatal Cult of Antihumanism'', which traces the history of [[antihumanism]] over the last two centuries, from [[Thomas Malthus]] and the [[eugenics]] movement through to the [[Anti-nuclear movement|anti-nuclear]] and "alarmist" DDT and [[Global warming controversy|global warming]] campaigns. Zubrin argues that these movements, by a number of means, including that of statistical mis-treatments, have all attempted to gain oppressive political control through the restriction of human activities and freedom.<ref>[https://www.theobjectivestandard.com/issues/2012-fall/review-merchants-of-despair/
Review: Merchants of Despair, by Robert Zubrin
Ted Gray February 2, 2014 In ''The Objective Standard'' Fall 2012]</ref>

==See also==
* [[Climate change controversy]]
* [[Climate change policy of the United States]]
* ''[[Climate Capitalism]]''
* [[Fear, uncertainty and doubt]]
* [[Greenhouse Mafia]]
* [[Health effects of tobacco]]
* [[List of books about the politics of science]]
* [[List of scientists opposing the mainstream scientific assessment of global warming]] in contrast with [[Scientific opinion on climate change]]
* [[Media coverage of climate change]]
* [[Scientific consensus]]
* [[Tobacco control movement]]
* [[Tobacco politics]]

=== Other books on the same theme ===
* ''[[Doubt Is Their Product: How Industry's Assault on Science Threatens Your Health]]'' (2008) by [[David Michaels (epidemiologist)|David Michaels]]
* ''Climate Cover-Up: The Crusade to Deny Global Warming'' (2009) by James Hoggan and Richard Littlemore
* ''[[Climate Change Denial: Heads in the Sand]]'' (2011) by Haydn Washington and John Cook

==References==
{{Reflist|30em}}

==External links==
* {{official website|http://www.merchantsofdoubt.org/index.html}}
* [http://www.abc.net.au/rn/scienceshow/stories/2011/3101369.htm Merchants of Doubt], Public Lecture (2010), [[University of NSW]], ''The Science Show'', [[ABC Radio National]], January 8, 2011.

{{Portal bar|Global warming|Environment}}

[[Category:2010 books]]
[[Category:2010 in the environment]]
[[Category:21st-century history books]]
[[Category:History books about science]]
[[Category:History books about politics]]
[[Category:Climate change books]]
[[Category:Climate change skepticism and denial]]
[[Category:Environmental non-fiction books]]
[[Category:Political books]]
[[Category:Books about the politics of science]]
[[Category:Books adapted into films]]
[[Category:Professional ethics]]
[[Category:Doubt]]

Merchants of Doubt

2017-12-10T23:09:39Z

Boundarylayer: /* Authors */ Curious why the attempt to counter this book, "merchants of despair" isn't mentioned in this article?

{{About|the book|the film based on the book|Merchants of Doubt (film)}}
{{Use mdy dates|date=December 2015}}
{{good article}}
{{Infobox book
| name = Merchants of Doubt: How a Handful of Scientists Obscured the Truth on Issues from Tobacco Smoke to Global Warming
| image = Merchants of DOUBT.jpg
| image_size = 197px
| caption =
| author = [[Naomi Oreskes]], [[Erik M. Conway]]
| illustrator =
| cover_artist =
| country =
| series =
| subject = Scientists—Professional Ethics Science news—Moral and ethical aspects
| published = June 3, 2010 [[Bloomsbury Press]]
| media_type =
| pages = 355 pp.
| isbn = 978-1-59691-610-4
| oclc = 461631066
| dewey = 174.95
| congress = Q147 .O74 2010
}}

'''''Merchants of Doubt: How a Handful of Scientists Obscured the Truth on Issues from Tobacco Smoke to Global Warming''''' is a 2010 non-fiction book by American [[History of science|historians of science]] [[Naomi Oreskes]] and [[Erik M. Conway]]. It identifies parallels between the [[global warming controversy]] and earlier controversies over [[tobacco smoking]], [[acid rain]], [[DDT]], and the [[ozone depletion|hole in the ozone layer]]. Oreskes and Conway write that in each case "keeping the controversy alive" by spreading doubt and confusion after a scientific consensus had been reached, was the basic strategy of those opposing action.<ref name = stek>{{cite news |author=Steketee, Mike |title=Some sceptics make it a habit to be wrong |url=http://www.theaustralian.com.au/national-affairs/some-sceptics-make-it-a-habit-to-be-wrong/story-fn59niix-1225956414538 |newspaper=[[The Australian]] |date=November 20, 2010 }}</ref> In particular, they say that [[Fred Seitz]], [[Fred Singer]], and a few other [[contrarian]] scientists joined forces with conservative [[think tank]]s and private corporations to challenge the scientific consensus on many contemporary issues.<ref>{{cite book |first1=Naomi |last1=Oreskes |first2=Erik M. |last2=Conway |title=Merchants of Doubt: How a Handful of Scientists Obscured the Truth on Issues from Tobacco Smoke to Global Warming |url=https://books.google.com/books?id=fpMh3nh3JI0C&pg=PP4 |year=2010 |publisher=Bloomsbury Press |isbn=978-1-59691-610-4 |page=6 |ref=harv}} [http://www.merchantsofdoubt.org/index.html merchantsofdoubt.org]</ref>

The [[George C. Marshall Institute]] and Fred Singer, two of the subjects, have been critical of the book. Other reviewers have been more favorable. One reviewer said that ''Merchants of Doubt'' is exhaustively researched and documented, and may be one of the most important books of 2010. Another reviewer saw the book as his choice for best [[science book]] of the year.<ref name=Mckie8/> It was made into a film, ''[[Merchants of Doubt (film)|Merchants of Doubt]]'', directed by [[Robert Kenner]], released in 2014.<ref>{{cite web | url=http://sonyclassics.com/merchantsofdoubt/ | title=Merchants of Doubt | publisher=Sony Pictures Classics | accessdate=March 8, 2015}}</ref>

==Themes==
[[File:S Fred Singer 2011.jpg |thumb|right |[[Fred Singer]] (2011), a prominent opponent of greenhouse gas regulation.]]
Oreskes and Conway write that a handful of [[Conservatism in the United States|politically conservative]] scientists, with strong ties to particular industries, have "played a disproportionate role in debates about controversial questions".<ref name=pk/> The authors write that this has resulted in "deliberate obfuscation" of the issues which has had an influence on [[Public opinion on climate change|public opinion]] and [[Climate change policy of the United States|policy-making]].<ref name=pk>{{cite journal |author=Kitcher, Philip |authorlink=Philip Kitcher |title=The Climate Change Debates |journal=[[Science (journal)|Science]] |volume=328 |issue=5983 |pages=1231–2 |date=June 4, 2010 |doi=10.1126/science.1189312 |url=http://www.sciencemag.org/cgi/content/full/328/5983/1230-a }}</ref>

The book criticizes the so-called Merchants of Doubt, some predominantly American science key players, above all [[William Nierenberg|Bill Nierenberg]], [[Fred Seitz]], and [[Fred Singer]]. All three are physicists: Singer was a [[rocket scientist]], whereas Nierenberg and Seitz worked on the atomic bomb.<ref name=sb>{{cite news |author=Brown, Seth |title='Merchants of Doubt' delves into contrarian scientists |url=https://www.usatoday.com/money/books/reviews/2010-06-01-deathmerchants01_ST_N.htm |newspaper=[[USA Today]] |date=May 31, 2010 }}</ref> They have been active on topics like acid rain, tobacco smoking, global warming and pesticides. The book claims that these scientists have challenged and diluted the [[scientific consensus]] in the various fields, as of the [[dangers of smoking]], the effects of acid rain, the existence of the ozone hole, and the existence of [[anthropogenic climate change]].<ref name=pk/> Seitz and Singer have been involved with institutions such as [[The Heritage Foundation]], [[Competitive Enterprise Institute]] and [[George C. Marshall Institute]] in the United States. Funded by [[corporation]]s and conservative [[Foundation (United States law)|foundations]], these organizations have opposed many forms of [[Economic interventionism|state intervention]] or regulation of U.S. citizens. The book lists similar tactics in each case: "discredit the science, disseminate false information, spread confusion, and promote doubt".<ref name=rm/>

The book states that Seitz, Singer, Nierenberg and [[Robert Jastrow]] were all fiercely [[Anti-communism|anti-communist]] and they viewed government regulation as a step towards [[socialism]] and [[communism]]. The authors argue that, with the [[collapse of the Soviet Union]], they looked for another great threat to free market capitalism and found it in environmentalism. They feared that an over-reaction to environmental problems would lead to heavy-handed government intervention in the marketplace and intrusion into people's lives.<ref name=ocmerch/> Oreskes and Conway state that the longer the delay the worse these problems get, and the more likely it is that governments will need to take the draconian measures that conservatives and [[market fundamentalism|market fundamentalists]] most fear. They say that Seitz, Singer, Nierenberg and Jastrow denied the scientific evidence, contributed to a strategy of delay, and thereby helped to bring about the situation they most dreaded.<ref name=ocmerch>{{harvnb|Oreskes|Conway|2010|pp=248–255}}</ref> The authors have a strong doubt about the ability of the media to differentiate between false truth and the actual science in question; however, they stop short of endorsing censorship in the name of science.<ref name ="RG" /> The journalistic norm of balanced reporting has helped, according to the authors, to amplify the misleading messages of the contrarians. Oreskes and Conway state: "small numbers of people can have large, negative impacts, especially if they are organised, determined and have access to power".<ref name=rm>{{cite news |author=McKie, Robin |title=A dark ideology is driving those who deny climate change |url=https://www.theguardian.com/commentisfree/2010/aug/01/climate-change-robin-mckie |newspaper=The Guardian |date=August 1, 2010 }}</ref>

The main conclusion of the book is that there would have been more progress in policymaking, if not for the influence of the contrarian "experts", which tried on ideological reasons to undermine trust in the science base for regulation.<ref name="RG">{{cite journal|last1=Grundmann|first1=Reiner|title=Debunking sceptical propaganda|journal=BioSocieties|date=29 August 2013|volume=8|issue=3|pages=370–374|doi=10.1057/biosoc.2013.15|url=https://www.academia.edu/4754580/Debunking_skeptical_propaganda_Book_review_of_Oreskes_Conway_Merchants_of_Doubt}}</ref> Similar conclusions were already drawn, among others on [[Frederick Seitz]] and [[William Nierenberg]] in the book ''[[Requiem for a Species|Requiem for a Species: Why We Resist the Truth about Climate Change]]'' (2010) by Australian academic [[Clive Hamilton]].

==Reception==

[[Philip Kitcher]] in ''[[Science (magazine)|Science]]'' says that Naomi Oreskes and Erik Conway are "two outstanding historians".<ref name=pk/> He calls ''Merchants of Doubt'' a "fascinating and important study". Kitcher says that the apparently harsh claims against Nierenberg, Seitz, and Singer are "justified through a powerful dissection of the ways in which prominent climate scientists, such as [[Roger Revelle]] and [[Ben Santer]], were exploited or viciously attacked in the press".<ref name=pk/>

In ''[[The Christian Science Monitor]]'', Will Buchanan says that ''Merchants of Doubt'' is exhaustively researched and documented, and may be one of the most important books of 2010. Oreskes and Conway are seen to demonstrate that the doubt merchants are not "objective scientists" as the term is popularly understood. Instead, they are "science-speaking mercenaries" hired by corporations to process numbers to prove that the corporations’ products are safe and useful. Buchanan says they are salesmen, not scientists.<ref>Buchanan, Will (June 22, 2010). [http://www.csmonitor.com/Books/Book-Reviews/2010/0622/Merchants-of-Doubt Merchants of Doubt: How “scientific” misinformation campaigns sold untruths to consumers] ''The Christian Science Monitor''.</ref>

Bud Ward published a review of the book in ''The Yale Forum on Climate and the Media''. He wrote that Oreskes and Conway use a combination of thorough scholarly research combined with writing reminiscent of the best investigative journalism, to "unravel deep common links to past environmental and public health controversies".<ref name="Ward">Ward, Bud (July 8, 2010). [http://www.yaleclimatemediaforum.org/2010/07/merchants-of-doubt/ Reviews: Leaving No Doubt on Tobacco, Acid Rain, Climate Change], ''The Yale Forum on Climate and the Media''.</ref> In terms of climate science, the authors' leave "little doubt about their disdain for what they regard as the misuse and abuse of science by a small cabal of scientists they see as largely lacking in requisite climate science expertise".<ref name="Ward" />

Phil England writes in ''[[The Ecologist]]'' that the strength of the book is the rigour of the research and the detailed focus on key incidents. He said, however, that the climate change chapter is only 50 pages long, and recommends several other books for readers who want to get a broader picture of this aspect: [[Jim Hoggan]]’s ''Climate Cover-Up'', [[George Monbiot]]’s ''Heat: How to Stop the Planet Burning'' and [[Ross Gelbspan]]’s ''The Heat is On'' and ''Boiling Point''. England also said that there is little coverage about the millions of dollars which [[Exxon Mobil]] has put into funding groups actively involved in promoting [[climate change denial]] and doubt.<ref>England, Phil (September 10, 2010). [http://www.theecologist.org/reviews/books/592288/merchants_of_doubt.html Merchants of Doubt] ''[[The Ecologist]]''.</ref>

A review in ''[[The Economist]]'' calls this a powerful book which articulates the politics involved and the degree to which scientists have sometimes manufactured and exaggerated environmental uncertainties, but opines that the authors fail to fully explain how environmental action has still often proved possible despite countervailing factors.<ref>[http://www.economist.com/node/16374460 All guns blazing: A question of dodgy science], (June 17, 2010), ''[[The Economist]]''.</ref>

[[Robert N. Proctor]], who coined the term "[[agnotology]]" to describe the study of culturally induced ignorance or doubt, wrote in ''[[American Scientist]]'' that ''Merchants of Doubt'' is a detailed and artfully written book. He set it in the context of other books which cover the "history of manufactured ignorance":<ref name="Proctor">Proctor, Robert (September–October 2010). [http://www.americanscientist.org/bookshelf/pub/manufactured-ignorance Book Review: Manufactured Ignorance], ''[[American Scientist]]''.</ref> [[David Michaels (epidemiologist)|David Michaels]]’s ''[[Doubt is their Product]]'' (2008), [[Chris Mooney (journalist)|Chris Mooney]]’s ''[[The Republican War on Science]]'' (2009), [[David Rosner]] and Gerald Markowitz’s ''[[Deceit and Denial]]'' (2002), and his own book ''[[Cancer Wars]]'' (1995).<ref name="Proctor" />

Robin McKie in ''[[The Guardian]]'' states that Oreskes and Conway deserve considerable praise for exposing the influence of a small group of [[Cold War]] ideologues. Their tactic of spreading doubt has confused the public about a series of key scientific issues such as global warming, even though scientists have actually become more certain about their research results. McKie says that ''Merchants of Doubt'' includes detailed notes on all sources used, is carefully paced, and is "my runaway contender for best science book of the year".<ref name=Mckie8>McKie, Robin (August 8, 2010). [https://www.theguardian.com/books/2010/aug/08/merchants-of-doubt-oreskes-conway "Merchants of Doubt by Naomi Oreskes and Erik M Conway".] ''The Guardian''.</ref>

Sociologist [[Reiner Grundmann]]'s review in ''[[BioSocieties]]'' journal, acknowledges that the book is well researched and factually based, but criticizes the book as being written in a black and white manner whereas historians should write a more nuanced description. The book depicts special interests and contrarians misleading the public as being mainly responsible for stopping action on policy. He says this shows a lack of basic understanding of the political process and the mechanisms of [[knowledge policy]], because the authors assume that public policy would follow on from an understanding of the science. While the book provides ''all the (formal) hallmarks of science'', Grundmann sees it less as a scholarly work than a passionate attack and overall as a problematic book.<ref name="RG" />

William O’Keefe and Jeff Kueter from the [[George C. Marshall Institute]], which was founded by Seitz,<ref>{{cite web|last1=Begley|first1=Sharon|title=Global Warming Deniers: A Well-Funded Machine|url=http://www.newsweek.com/global-warming-deniers-well-funded-machine-99295|website=Newsweek|date=4 August 2007|quote=...a central cog in the denial machine: the George C. Marshall Institute, a conservative think tank.}}</ref> say that although ''Merchants of Doubt'' has the appearance of a scholarly work, it discredits and undermines the reputations of people who in their lifetime contributed greatly to the American nation. They say that it does this by questioning their integrity, impugning their character, and questioning their judgement.<ref>{{cite web | last=O’Keefe | first= William |last2= Kueter| first2=Jeff | date=June 2010 | url=http://marshall.org/wp-content/uploads/2011/06/OKeefe-and-Kueter-Clouding-the-Truth-A-Critique-of-Merchants-of-Doubt.pdf |title=Clouding the Truth: A Critique of Merchants of Doubt |publisher=[[George C. Marshall Institute]] |work=Policy Outlook | quote=Although cloaked in the appearance of scholarly work, the book constitutes an effort to discredit and undermine the reputations of three deceased scientists who contributed greatly to our nation... This book questions their integrity, impugns their character, and questions their judgment on the basis of little more than faulty logic and preconceived opinion}}</ref>

==Authors==
[[File:Naomi Oreskes 2nd European TA conference in Berlin 2015 (cropped to collar).JPG |thumb|right |[[Naomi Oreskes]] (2015), co-author of ''Merchants of Doubt''.]]
Naomi Oreskes is Professor of History and Science Studies at Harvard University. She has degrees in geological science and a [[Doctor of Philosophy|Ph.D.]] in [[Geological]] Research and the History of Science. Her work came to public attention in 2004 with the publication of "The Scientific Consensus on Climate Change," in ''Science'', in which she wrote that there was no significant disagreement in the scientific community about the reality of global warming from human causes.<ref name=collins>[http://www.marcovigevani.com/upload/london_2008/Collins_Literary_London_2008_Rights_List.pdf Collins Literary Agency Rights Guide/March 2008]</ref> Erik M. Conway is the historian at [[NASA]]'s [[Jet Propulsion Laboratory]] at the [[California Institute of Technology]] in [[Pasadena, California|Pasadena]].<ref name=collins/>

==Counterargument==
In 2011, aerospace engineer [[Robert Zubrin]], most famous for [[The Case for Mars]], penned a book length response, titled ''Merchants of Despair: Radical Environmentalists, Criminal Pseudo-Scientists, and the Fatal Cult of Antihumanism'', which traces the history of [[antihumanism]] over the last two centuries, from [[Thomas Malthus]] and the [[eugenics]] movement through to the [[Anti-nuclear movement|anti-nuclear]] and "alarmist" DDT and [[Global warming controversy|global warming]] campaigns. Zubrin argues that these movements have all represented an attempt to gain oppressive political control through the restriction of human activities and freedom.<ref>[https://www.theobjectivestandard.com/issues/2012-fall/review-merchants-of-despair/
Review: Merchants of Despair, by Robert Zubrin
Ted Gray February 2, 2014 In ''The Objective Standard'' Fall 2012]</ref>

==See also==
* [[Climate change controversy]]
* [[Climate change policy of the United States]]
* ''[[Climate Capitalism]]''
* [[Fear, uncertainty and doubt]]
* [[Greenhouse Mafia]]
* [[Health effects of tobacco]]
* [[List of books about the politics of science]]
* [[List of scientists opposing the mainstream scientific assessment of global warming]] in contrast with [[Scientific opinion on climate change]]
* [[Media coverage of climate change]]
* [[Scientific consensus]]
* [[Tobacco control movement]]
* [[Tobacco politics]]

=== Other books on the same theme ===
* ''[[Doubt Is Their Product: How Industry's Assault on Science Threatens Your Health]]'' (2008) by [[David Michaels (epidemiologist)|David Michaels]]
* ''Climate Cover-Up: The Crusade to Deny Global Warming'' (2009) by James Hoggan and Richard Littlemore
* ''[[Climate Change Denial: Heads in the Sand]]'' (2011) by Haydn Washington and John Cook

==References==
{{Reflist|30em}}

==External links==
* {{official website|http://www.merchantsofdoubt.org/index.html}}
* [http://www.abc.net.au/rn/scienceshow/stories/2011/3101369.htm Merchants of Doubt], Public Lecture (2010), [[University of NSW]], ''The Science Show'', [[ABC Radio National]], January 8, 2011.

{{Portal bar|Global warming|Environment}}

[[Category:2010 books]]
[[Category:2010 in the environment]]
[[Category:21st-century history books]]
[[Category:History books about science]]
[[Category:History books about politics]]
[[Category:Climate change books]]
[[Category:Climate change skepticism and denial]]
[[Category:Environmental non-fiction books]]
[[Category:Political books]]
[[Category:Books about the politics of science]]
[[Category:Books adapted into films]]
[[Category:Professional ethics]]
[[Category:Doubt]]

Benutzer:Snackroeg/Kernreaktoren der Generation 5

2016-12-05T17:25:51Z

Boundarylayer: /* Advantages and disadvantages */

[[File:GenIVRoadmap-en.svg|thumb|480px|Nuclear Energy Systems Deployable no later than 2030 and offering significant advances in sustainability, safety and reliability, and economics]]

'''Generation IV reactors''' ('''Gen IV''') are a set of [[nuclear reactor]] designs currently being researched for commercial applications by the Generation IV International Forum, with [[Technology readiness level]]s varying between the level requiring a demonstration, to economical competitive implementation. They are motivated by a variety of goals including improved safety, sustainability, efficiency, and cost.

Most of these designs are generally not expected to be available for commercial construction before 2030–40.<ref name="Generation IV">[http://www.world-nuclear.org/info/Nuclear-Fuel-Cycle/Power-Reactors/Generation-IV-Nuclear-Reactors/]</ref> Presently the majority of reactors in operation around the world are considered [[Generation II reactor|second generation reactor]] systems, as the vast majority of the [[Generation I reactor|first-generation]] systems were retired some time ago, and there are only a dozen or so [[Generation III reactor]]s in operation (2014). [[Nuclear reactor#Generation V+ reactors|Generation V reactors]] refer to reactors that are purely theoretical and are therefore not yet considered feasible in the short term, resulting in limited [[R&D]] funding.

== History ==
The Generation IV International Forum (GIF) is "a co-operative international endeavour which was set up to carry out the research and development needed to establish the feasibility and performance capabilities of the next generation nuclear energy systems."<ref>{{Cite web|url=https://www.gen-4.org/gif/jcms/c_9260/public|title=GIF Portal - Home - Public|website=www.gen-4.org|access-date=2016-07-25}}</ref> It was founded in 2001. There are currently ten active members of the Generation IV International Forum (GIF): [[Canada]], [[China]], the [[European Atomic Energy Community]] (Euratom), [[France]], [[Japan]], [[Russia]], [[South Africa]], [[South Korea]], [[Switzerland]], and the [[United States]]. The non-active members are [[Argentina]], [[Brazil]], and the [[United Kingdom]].<ref name="gen-4">{{cite web|url=https://www.gen-4.org/gif/jcms/c_9492/members|title=GIF Membership|website=gen-4.org|accessdate=28 October 2014}}</ref> Switzerland joined in 2002, Euratom in 2003, and China and Russia in 2006. The remaining countries (excluding Australia) were founding members.<ref name="gen-4" />

The 36th GIF meeting in [[Brussels]] was held in November 2013.<ref>{{cite web|url=http://www.energy.gov/ne/articles/generation-iv-international-forum-updates-technology-roadmap-and-builds-future|title=generation IV international forum updates technology roadmap and builds future. DOE}}</ref><ref>{{cite web|url=http://events.r20.constantcontact.com/register/event?llr=mscrkjkab&oeidk=a07e7melf609716b2c6|title=The Generation IV international forum holds their 36th meeting on Monday 18th Nov 2013 in Brussels.}}</ref> The ''Technology Roadmap Update for Generation IV Nuclear Energy Systems'' was published in January 2014 which details R&D objectives for the next decade.<ref>[https://web.archive.org/web/20140625102915/https://www.gen-4.org/gif/upload/docs/application/pdf/2014-03/gif-tru2014.pdf Technology Roadmap Update for Generation IV Nuclear Energy Systems]</ref> A breakdown of the reactor designs being researched by each forum member has been made available.<ref>[https://web.archive.org/web/20140708023538/https://www.gen-4.org/gif/upload/docs/application/pdf/2014-03/gif_overview_presentation_v9_final3_web.pdf Generation IV International Forum, overview, John E. Kelly, page 15]</ref>

[[Nuclear power in Australia|Australia]] joined the forum in 2016.<ref>http://archive.is/22e5F</ref>

== Reactor types ==
Many reactor types were considered initially; however, the list was downsized to focus on the most promising technologies and those that could most likely meet the goals of the Gen IV initiative.<ref name="Generation IV"/> Three systems are nominally [[thermal reactor]]s and three are [[fast reactor]]s. The Very High Temperature Reactor (VHTR) is also being researched for potentially providing high quality process heat for [[thermochemical cycle|hydrogen production]]. The fast reactors offer the possibility of burning [[actinides]] to further reduce waste and of being able to "[[breeder reactor|breed more fuel]]" than they consume. These systems offer significant advances in sustainability, safety and reliability, economics, proliferation resistance (depending on perspective) and physical protection.

=== Thermal reactors ===
A [[Thermal-neutron reactor|thermal reactor]] is a [[nuclear reactor]] that uses slow or [[thermal neutrons]]. A [[neutron moderator]] is used to slow the [[neutron]]s emitted by fission to make them more likely to be captured by the fuel.

==== Very-high-temperature reactor (VHTR) ====
[[File:Very High Temperature Reactor.svg|right|thumb|Very-High-Temperature Reactor (VHTR)]]
{{Main article|Very high temperature reactor}}
{{see also|Fort St. Vrain Generating Station|HTTR|HTR-10}}
The '''very high temperature reactor''' concept uses a [[graphite]]-moderated core with a once-through [[uranium]] fuel cycle, using helium or molten salt as the [[Very high temperature reactor#Coolant|coolant]]. This reactor design envisions an outlet temperature of 1,000 °C. The reactor core can be either a prismatic-block or a [[pebble bed reactor]] design. The high temperatures enable applications such as process heat or [[hydrogen]] production via the thermochemical [[Sulfur-iodine cycle|iodine-sulfur]] process. It would also be [[Passive nuclear safety|passively safe]].

The planned construction of the first VHTR, the South African PBMR ([[pebble bed modular reactor]]), lost government funding in February, 2010.<ref>[http://www.powergenworldwide.com/index/display/articledisplay/6322207443/articles/power-engineering-international/volume-18/Issue_3/regulars/world-news/INTERNATIONAL.html South Africa to stop funding Pebble Bed nuclear reactor]</ref> A pronounced increase of costs and concerns about possible unexpected technical problems had discouraged potential investors and customers.

The [[Peoples Republic of China]] began construction of a 200-MW High Temperature Pebble bed reactor in 2012 as a successor to its [[HTR-10]].<ref>[http://www.nucnet.org/all-the-news/2013/01/07/china-begins-construction-of-first-generation-iv-htr-pm-unit Nucnet Report: 'China Begins Construction of First Generation IV HTR-PM Unit', 7 January 2013]</ref>

Also in 2012, as part of the [[Next Generation Nuclear Plant]] competition, [[Idaho National Laboratory]] approved a design similar to [[Areva]]'s prismatic block [http://us.areva.com/EN/home-3225/areva-inc-areva-htgr.html Antares reactor] as the chosen [[HTGR]] to be deployed as a prototype by 2021. It was in competition with [[General Atomics]]' [[Gas turbine modular helium reactor]] and [[Westinghouse Electric Company|Westinghouse]]'s [[Pebble Bed Modular Reactor]].<ref name="World nuclear news">{{cite web|url=http://www.world-nuclear-news.org/NN-Areva_modular_reactor_selected_for_NGNP_development-1502124.html|title=INL approves Antares design}}</ref>

==== Molten-salt reactor (MSR) ====
[[File:Molten Salt Reactor.svg|right|thumb|Molten Salt Reactor (MSR)]]
{{Main article|Molten salt reactor}}
{{see also|Liquid fluoride thorium reactor}}
A '''molten salt reactor'''<ref name="Roadmap"/> is a type of [[nuclear reactor]] where the primary [[coolant]], or even the fuel itself is a molten salt mixture. There have been many designs put forward for this type of reactor and a few prototypes built. The early concepts and many current ones rely on [[nuclear fuel]] dissolved in the molten [[fluoride]] salt as [[uranium tetrafluoride]] (UF4) or [[thorium tetrafluoride]] (ThF4). The fluid would reach [[Nuclear reactor physics#Criticality|criticality]] by flowing into a [[graphite]] core which would also serve as the [[neutron moderator|moderator]]. Many current concepts rely on fuel that is dispersed in a graphite matrix with the molten salt providing low pressure, high temperature cooling.

The Gen IV MSR is more accurately termed an [[epithermal neutron|epithermal reactor]] than a thermal reactor due to the average speed of the neutrons that would cause the fission events within its fuel being faster than [[thermal neutron]]s.<ref>{{cite web |url=https://inlportal.inl.gov/portal/server.pt?open=514&objID=1361&parentname=CommunityPage&parentid=10&mode=2&in_hi_userid=200&cached=true |title=Idaho National Laboratory detailing some current efforts at developing Gen. IV reactors}}</ref>

The principle of a MSR can be used for thermal, epithermal and fast reactors. Since 2005 the focus has moved towards a fast spectrum MSR (MSFR).<ref>H. Boussier, S. Delpech, V. Ghetta et Al. : The Molten Salt Reactor (MSR) in Generation IV: Overview and Perspectives, GIF SYMPOSIUM PROCEEDINGS/2012 ANNUAL REPORT, NEA No. 7141, pp95 [https://www.gen-4.org/gif/jcms/c_44720/annual-reports]
</ref>

While most MSR designs being pursued are largely derived from the 1960s [[Molten-Salt Reactor Experiment]](MSRE), variants of molten salt technology include the conceptual ''[[Dual fluid reactor]]'' which is being designed with lead as a cooling medium but molten salt fuel, commonly as the metal chloride e.g [[Plutonium(III) chloride]], to aid in greater "nuclear waste" closed-fuel cycle capabilities.
Other notable approaches differing substantially from those with MSRE [[pedigree]] include the ''[[Stable Salt Reactor]]''(SSR) concept promoted by MOLTEX, which encases the molten salt in hundreds of the common solid [[fuel rod]]s that are already well established in the nuclear industry. This latter British design was found to be the most competitive for [[Small modular reactor]] development by a British based consultancy firm ''Energy Process Development'' in 2015.<ref>[http://www.daretothink.org/europe-moltex-stable-salt-reactor/ Europe: Moltex’ Stable Salt Reactor]</ref><ref>[http://analysis.nuclearenergyinsider.com/moltex-energy-sees-uk-canada-smr-licensing-springboard-asia Moltex Energy sees UK, Canada SMR licensing as springboard to Asia Jun 28, 2016]</ref>

==== Supercritical-water-cooled reactor (SCWR) ====
[[File:Supercritical-Water-Cooled Reactor.svg|right|thumb|Supercritical-Water-Cooled Reactor (SCWR)]]
{{Main article|Supercritical water reactor}}
The '''supercritical water reactor''' (SCWR)<ref name="Roadmap"/> is a [[reduced moderation water reactor]] concept that, due to the average speed of the neutrons that would cause the fission events within the fuel being faster than [[thermal neutron]]s, it is more accurately termed an [[epithermal neutron|epithermal reactor]] than a thermal reactor. It uses [[supercritical fluid|supercritical water]] as the working fluid. SCWRs are basically [[light water reactor]]s (LWR) operating at higher pressure and temperatures with a direct, once-through heat exchange cycle. As most commonly envisioned, it would operate on a direct cycle, much like a boiling water reactor ([[BWR]]), but since it uses supercritical water (not to be confused with [[Critical mass (nuclear)|critical mass]]) as the working fluid, it would have only one water phase present, which makes the supercritical heat exchange method more similar to a pressurized water reactor ([[Pressurized water reactor|PWR]]). It could operate at much higher temperatures than both current PWRs and BWRs.

Supercritical water-cooled reactors (SCWRs) are promising advanced nuclear systems because of their high [[thermal efficiency]] (i.e., about 45% vs. about 33% efficiency for current LWRs) and considerable plant simplification.

The main mission of the SCWR is generation of low-cost [[electricity]]. It is built upon two proven technologies, LWRs, which are the most commonly deployed power generating reactors in the world, and superheated [[fossil fuel]] fired [[boiler]]s, a large number of which are also in use around the world. The SCWR concept is being investigated by 32 organizations in 13 countries.{{citation needed|date=October 2012}}

A SCWR Design under development is the [[VVER]]-1700/393 (VVER-SCWR or VVER-SKD) — a Russian Supercritical-water-cooled reactor with double-inlet-core and a [[breeder reactor|breeding ratio]] of 0.95.<ref name="powertecrussia.com">{{cite web |url=http://www.powertecrussia.com/blog/tag/nuclear-power/ |title=Technology Developments & Plant Efficiency for the Russian Nuclear Power Generation Market Wednesday |date=March 24, 2010}}</ref>

=== Fast reactors ===
A [[Fast-neutron reactor|fast reactor]] directly uses the fast neutrons emitted by fission, without moderation. Unlike thermal neutron reactors, fast neutron reactors can be configured to "'''burn'''", or fission, all [[actinides]], and given enough time, therefore drastically reduce the actinides fraction in [[spent nuclear fuel]] produced by the present world fleet of thermal neutron [[light water reactor]]s, thus closing the [[nuclear fuel cycle]]. Alternatively, if configured differently, they can also [[breeder reactor|'''breed''']] more actinide fuel than they consume.

==== Gas-cooled fast reactor (GFR) ====
[[File:Gas-Cooled Fast Reactor Schemata.svg|right|thumb|Gas-Cooled Fast Reactor (GFR)]]
{{Main article|Gas-cooled fast reactor}}
The '''gas-cooled fast reactor''' (GFR)<ref name="Roadmap"/> system features a fast-neutron spectrum and closed fuel cycle for efficient conversion of [[Fertile material|fertile uranium]] and management of actinides. The reactor is [[helium]]-cooled and with an outlet temperature of 850 °C it is an evolution of the [[very-high-temperature reactor]] (VHTR) to a more sustainable fuel cycle. It will use a direct [[Brayton cycle]] [[Closed-cycle gas turbine|gas turbine]] for high thermal efficiency. Several fuel forms are being considered for their potential to operate at very high temperatures and to ensure an excellent retention of [[Nuclear fission|fission]] products: composite [[ceramic]] fuel, advanced fuel particles, or ceramic clad elements of actinide compounds. Core configurations are being considered based on pin- or plate-based fuel assemblies or prismatic blocks.

The European Sustainable Nuclear Industrial Initiative is funding three Generation IV reactor systems, one of which is a gas-cooled fast reactor, called ''Allegro'', 100 MW(t), which will be built in a central or eastern European country with construction expected to begin in 2018.<ref name="euronuclear.org">{{cite web |url=https://www.euronuclear.org/1-information/news/Gen-IV.htm |title=The European Sustainable Nuclear Industrial Initiative (ESNII) will support three Generation IV reactor systems: a sodium-cooled fast reactor, or SFR, called ''Astrid'' that is proposed by France; a gas-cooled fast reactor, GFR, called ''Allegro'' supported by central and eastern Europe; and a lead-cooled fast reactor, LFR, technology pilot called ''Myrrha'' that is proposed by Belgium.}}</ref> The central European [[Visegrád Group]] are committed to pursuing the technology.<ref>{{cite web |url=http://www.alphagalileo.org/ViewItem.aspx?ItemId=133111&CultureCode=en |title=The V4G4 Centre of Excellence for performing joint research, development and innovation in the field of Generation-4 (G4) nuclear reactors have been established. 20 July 2013 National Center for Nuclear Research (NCBJ]}}</ref> In 2013 German, British, and French institutes finished a 3-year collaboration study on the follow on industrial scale design, known as ''GoFastR''.<ref>{{cite web |url=http://www.ist-world.org/ProjectDetails.aspx?ProjectId=5cb8f3f283574cc6b2bdbf72533172d8 |title=the European Gas cooled Fast Reactor.}}</ref> They were funded by the EU's 7th FWP [[framework programme]], with the goal of making a sustainable VHTR.<ref>{{cite web |url=http://www.2020-horizon.com/GOFASTR-European-Gas-Cooled-Fast-Reactor%28GOFASTR%29-s312.html |title=The GOFASTR research program}}</ref>

==== Sodium-cooled fast reactor (SFR) ====
[[File:Sodium-Cooled Fast Reactor Schemata.svg|right|thumb|Pool design Sodium-Cooled Fast Reactor (SFR)]]
{{Main article|Sodium-cooled fast reactor}}
{{see also|Prototype Fast Breeder Reactor|Experimental Breeder Reactor II|S-PRISM|BN-800 reactor|Toshiba 4S}}

In India, the [[Fast Breeder Test Reactor]] reached criticality in October 1985. In September 2002, fuel burn-up in the FBTR for the first time reached the 100,000 megawatt-days per metric ton uranium (MWd/MTU) mark. This is considered an important milestone in breeder reactor technology. Using the experience gained from the operation of the FBTR, the [[Prototype Fast Breeder Reactor]], a 500 MWe Sodium cooled fast reactor is being built at a cost of INR 5,677 crores (~US$900 million) and is expected to be critical by June 2016. The PFBR will be followed by six more Commercial Fast Breeder Reactors (CFBRs) of 600 MWe each.

The SFR<ref name="Roadmap"/> is a project that builds on two closely related existing projects, the liquid metal [[Breeder reactor#Fast breeder reactor|fast breeder reactor]] and the [[integral fast reactor]].

The goals are to increase the efficiency of uranium usage by [[breeder reactor|breeding]] plutonium and eliminating the need for [[transuranic]] isotopes ever to leave the site. The reactor design uses an unmoderated core running on [[fast neutron]]s, designed to allow any transuranic isotope to be consumed (and in some cases used as fuel). In addition to the benefits of removing the long [[half-life]] transuranics from the waste cycle, the SFR fuel expands when the reactor overheats, and the chain reaction automatically slows down. In this manner, it is passively safe.<ref>{{cite web |url=http://www.ne.anl.gov/About/hn/logos-winter02-psr.shtml|title=Passively safe reactors rely on nature to keep them cool|author=David Baurac}}</ref>

The SFR reactor concept is cooled by liquid [[sodium]] and fueled by a metallic alloy of uranium and [[plutonium]] or [[spent nuclear fuel]], the "nuclear waste" of [[light water reactor]]s. The SFR fuel is contained in steel cladding with liquid sodium filling in the space between the clad elements which make up the fuel assembly. One of the design challenges of an SFR is the risks of handling sodium, which reacts explosively if it comes into contact with water. However, the use of liquid metal instead of water as coolant allows the system to work at atmospheric pressure, reducing the risk of leakage.

The European Sustainable Nuclear Industrial Initiative is funding three Generation IV reactor systems, one of which is a sodium-cooled fast reactor, called ''[[ASTRID (reactor)|ASTRID]]'', Advanced Sodium Technical Reactor for Industrial Demonstration, [[Areva]], [[Commissariat à l'énergie atomique et aux énergies alternatives|CEA]] and [[Électricité de France|EDF]] are leading the design with British collaboration.<ref>{{cite web |url=http://www.power-eng.com/articles/2010/11/areva--cea-secure.html |title=Areva, CEA secure EUR650m funding to develop ASTRID sodium-cooled Generation IV reactor 11/11/2010}}</ref><ref>{{cite web |url=http://www.powermag.com/uk-and-france-sign-landmark-civil-nuclear-cooperation-agreement/ |title=UK and France Sign Landmark Civil Nuclear Cooperation Agreement 02/22/2012 . POWERnews}}</ref> Astrid will be rated about 600 MWe and is proposed to be built in France, near to the [[Phénix]] reactor. A final decision in construction is to be made in 2019<ref name="euronuclear.org"/>

The [[China|PRC]]'s first commercial-scale, 800 MWe, fast neutron reactor, to be situated near [[Sanming]] in [[Fujian province]] will be a SFR. In 2009 an agreement was signed that would entail the Russian [[BN-800 reactor]] design to be sold to the PRC once it is completed, this would be the first time commercial-scale fast neutron reactors have ever been exported.<ref>{{cite web |url=http://www.world-nuclear-news.org/C-Joint_venture_launched_for_Chinese_fast_reactor-3004104.html |title=Joint venture launched for Chinese fast reactor}}</ref> The BN-800 reactor became operational in 2014.

The 400 MWe [[Fast Flux Test Facility]] operated successfully for ten years at the Hanford site in Washington State.

The 20 MWe [[EBR II]] operated successfully for over thirty years at the Idaho National Laboratory, until it was shut down in 1994.

==== Lead-cooled fast reactor (LFR) ====
[[File:Lead-Cooled Fast Reactor Schemata.svg|right|thumb|Lead-Cooled Fast Reactor (LFR)]]
{{Main article|Lead-cooled fast reactor}}
{{See also|MYRRHA}}
The '''lead-cooled fast reactor'''<ref name="Roadmap">{{cite journal| year=2002 | title=A Technology Roadmap for Generation IV Nuclear Energy Systems | last=US DOE Nuclear Energy Research Advisory Committee |volume=GIF-002-00|url=http://nuclear.energy.gov/genIV/documents/gen_iv_roadmap.pdf}}</ref> features a fast-neutron-spectrum [[lead]] or [[lead]]/[[bismuth]] [[eutectic]] ([[Lead-bismuth eutectic|LBE]]) liquid-metal-cooled reactor with a closed [[Nuclear fuel cycle|fuel cycle]]. Options include a range of plant ratings, including a "battery" of 50 to 150 MW of electricity that features a very long refueling interval, a modular system rated at 300 to 400 MW, and a large monolithic plant option at 1,200 MW. (The term ''battery'' refers to the long-life, factory-fabricated core, not to any provision for electrochemical energy conversion.) The fuel is metal or nitride-based containing [[Fertile material|fertile uranium]] and [[transuranic]]s. The LFR is cooled by natural [[convection]] with a reactor outlet coolant temperature of 550 °C, possibly ranging up to 800 °C with advanced materials. The higher temperature enables the production of [[Thermochemical cycle|hydrogen by thermochemical processes]].

The European Sustainable Nuclear Industrial Initiative is funding three Generation IV reactor systems, one of which is a lead-cooled fast reactor that is also an [[Subcritical reactor|accelerator-driven sub-critical]] reactor, called ''[[MYRRHA]]'', 100 MW(t), which will be built in [[Belgium]] with construction expected to begin after 2014 and the industrial scale version, known as ''Alfred'', slated to be constructed sometime after 2017. A reduced-power model of Myrrha called ''Guinevere'' was started up at [[Mol, Belgium|Mol]] in March 2009.<ref name="euronuclear.org"/> In 2012 the research team reported that Guinevere was operational.<ref>{{cite news|last1=Hellemans|first1=Alexander|title=Reactor-Accelerator Hybrid Achieves Successful Test Run|url=http://news.sciencemag.org/physics/2012/01/reactor-accelerator-hybrid-achieves-successful-test-run|accessdate=29 December 2014|work=Science Insider|date=12 January 2012}}</ref>

Two other lead-cooled fast reactors under development are the SVBR-100, a modular 100 MWe lead-bismuth cooled fast neutron reactor concept designed by OKB [[Gidropress]] in Russia and the [[BREST (Reactor)|BREST-OD-300]] (Lead-cooled fast reactor) 300 MWe, to be developed after the SVBR-100, and built over 2016-20, it will dispense with the [[Uranium-238|fertile blanket]] around the core and will supersede the sodium cooled [[BN-600 reactor]] design, to purportedly give enhanced proliferation resistance.<ref name="powertecrussia.com"/>

== Advantages and disadvantages ==
Relative to current nuclear power plant technology, the claimed benefits for 4th generation reactors include:
* Nuclear waste that remains radioactive for a few centuries instead of millennia<ref>{{cite web |title=Strategies to Address Global Warming |url=http://www.columbia.edu/~jeh1/mailings/2009/20090713_Strategies.pdf}}</ref>
* 100-300 times more energy yield from the same amount of nuclear fuel<ref>{{cite web |title=4th Generation Nuclear Power |url=http://www.ossfoundation.us/projects/energy/nuclear}}</ref>
* Broader range of fuels, and even unencapsulated raw fuels (non-pebble [[Molten Salt Reactor|MSR]], [[LFTR]]).
* In some reactors, the ability to consume existing nuclear waste in the production of electricity, that is, a Closed [[nuclear fuel cycle]]. This strengthens the argument to deem [[nuclear power as renewable energy]].
* Improved operating safety features, such as (depending on design) avoidance of pressurized operation, automatic passive (unpowered, uncommanded) reactor shutdown, avoidance of water cooling and the associated risks of loss of water (leaks or boiling) and hydrogen generation/explosion and contamination of coolant water.

Nuclear reactors do not emit CO2 during operation, although like all [[low carbon power]] sources, the mining and construction phase can result in CO2 emissions, if energy sources which are not carbon neutral (such as fossil fuels), or CO2 emitting cements are used during the construction process.
A 2012 [[Yale University]] review published in the Journal of Industrial Ecology analyzing {{CO2}} [[life cycle assessment]] (LCA) emissions from [[nuclear power]] determined that:<ref name="Warner + Heath, JoIE">Warner, Ethan S.; Heath, Garvin A. [http://onlinelibrary.wiley.com/doi/10.1111/j.1530-9290.2012.00472.x/full Life Cycle Greenhouse Gas Emissions of Nuclear Electricity Generation: Systematic Review and Harmonization], ''Journal of Industrial Ecology'', [[Yale University]], published online April 17, 2012, doi: 10.1111/j.1530-9290.2012.00472.x.</ref>
{{Quote|''"The collective LCA literature indicates that life cycle [[Greenhouse gas|GHG]] [ greenhouse gas ] emissions from nuclear power are only a fraction of traditional fossil sources and comparable to renewable technologies."''}}
Although the paper primarily dealt with data from [[Generation II reactor]]s, and did not analyze the {{CO2}} emissions by 2050 of the presently under construction [[Generation III reactor]]s, it did summarize the Life Cycle Assessment findings of in development reactor technologies.''{{Quote|FBRs ''[ [[Fast Breeder Reactor]]s ]'' have been evaluated in the LCA literature. The limited literature that evaluates this potential future technology reports [[median]] life cycle GHG emissions... similar to or lower than LWRs[ Gen II [[light water reactor]]s ] and purports to consume little or no [[uranium market|uranium ore]].}}

A specific risk of the sodium-cooled fast reactor is related to using metallic sodium as a coolant. In case of a breach, sodium explosively reacts with water. Fixing breaches may also prove dangerous, as the cheapest noble gas [[argon]] is also used to prevent sodium oxidation. Argon, like helium, can displace oxygen in the air and can pose [[hypoxia (environmental)|hypoxia]] concerns, so workers may be exposed to this additional risk. This is a pertinent problem as can be testified by the events at the [[LMFBR|loop type]] [[Monju Nuclear Power Plant|Prototype Fast Breeder Reactor Monju]] at Tsuruga, Japan.<ref>{{cite news |title=Japan Strains to Fix a Reactor Damaged Before Quake |url=http://www.nytimes.com/2011/06/18/world/asia/18japan.html | work=The New York Times | first=Hiroko |last=Tabuchi |date=17 June 2011}}</ref>
Using lead or molten salts mitigates this problem by making the coolant less reactive and allowing a high freezing temperature and low pressure in case of a leak. Disadvantages of lead compared to sodium are much higher viscosity, much higher density, lower heat capacity, and more radioactive neutron activation products.

In many cases, there is already a large amount of experience built up with numerous proof of concept Gen IV designs. For example, the reactors at [[Fort St. Vrain Generating Station]] and [[HTR-10]] are similar to the proposed Gen IV [[VHTR]] designs, and the [[LMFBR|pool type]] [[EBR-II]], [[Phénix]] and [[BN-600]] reactor are similar to the proposed pool type Gen IV Sodium Cooled Fast reactors being designed.

== Table of designs ==

{| class=wikitable
|-
! System
! Neutron Spectrum
! Coolant
! Temperature (°C)
! Fuel Cycle
! Size (MW)
!Example developers
|-
| [[Very high temperature reactor|VHTR]]
| Thermal
| Helium
| 900–1000
| Open
| 250–300
|[[Japan Atomic Energy Agency|JAEA]] ([[HTTR]]), [[Tsinghua University]] ([[HTR-10]]), X-energy<ref name="energy.gov">{{cite web|title=Energy Department Announces New Investments in Advanced Nuclear Power Reactors...|url=http://www.energy.gov/articles/energy-department-announces-new-investments-advanced-nuclear-power-reactors-help-meet|website=[[United States Department of Energy|US Department of Energy]]|accessdate=16 January 2016}}</ref>
|-
| [[Sodium-cooled fast reactor|SFR]]
| Fast
| Sodium
| 550
| Closed
| 30–150, 300–1500, 1000–2000
|[[TerraPower]] ([[Traveling wave reactor|TWR]]), Toshiba ([[Toshiba 4S|4S]]), [[GE Hitachi Nuclear Energy]] ([[PRISM (reactor)|PRISM]])
|-
| [[Supercritical water reactor|SCWR]]
| Thermal/fast
| Water
| 510–625
| Open/closed
| 300–700, 1000–1500
|
|-
| [[Gas-cooled fast reactor|GFR]]
| Fast
| Helium
| 850
| Closed
| 1200
|[[Energy Multiplier Module]]
|-
| [[Lead-cooled fast reactor|LFR]]
| Fast
| Lead
| 480–800
| Closed
| 20–180, 300–1200, 600–1000
|
|-
| [[Molten salt reactor|MSR]]
| Fast/thermal
| Fluoride/Chloride salts
| 700–800
| Closed
| 250, 1000
|[[Flibe Energy]] ([[Liquid fluoride thorium reactor|LFTR]]), [[Transatomic Power]], Thorium Tech Solution ([[Fuji Molten Salt Reactor|FUJI MSR]]), Terrestrial Energy ([[IMSR]]), [[Southern Company Services|Southern Company]]<ref name="energy.gov"/>
|}
<ref>https://www.gen-4.org/gif/upload/docs/application/pdf/2013-09/gif_rd_outlook_for_generation_iv_nuclear_energy_systems.pdf</ref>

== See also ==
{{colbegin|3}}
* [[Nuclear reactor]]
* [[Nuclear material]]
* [[Nuclear physics]]
* [[List of reactor types#Reactor types|List of reactor types]]
* [[Generation II reactor]]
* [[Generation III reactor]]
* [[Integral Fast Reactor]]
* [[Liquid fluoride thorium reactor]]
* [[Breeder reactor]]
* [[Small modular reactor]]
{{colend}}

==References==
{{Reflist|30em}}

== External links ==
* [https://inlportal.inl.gov/portal/server.pt?open=514&objID=1361&parentname=CommunityPage&parentid=10&mode=2&in_hi_userid=200&cached=true Article from Idaho National Laboratory detailing some current efforts at developing Gen. IV reactors.]
* [http://www.gen-4.org/ Generation IV International Forum (GIF)]
* [http://nuclear.energy.gov/genIV/neGenIV1.html U.S. Department of Energy Office of Nuclear Energy, Science and Technology]
* [http://www.engr.utk.edu/nuclear/colloquia/slides/Gen%20IV%20U-Tenn%20Presentation.pdf Gen IV presentation]
* [http://www.ecology.at/ecology/files/pr577_1.pdf Science or Fiction - Is there a Future for Nuclear?] (Nov. 2007) - A publication from the Austrian [[Ecology Institute (Austria)|Ecology Institute]] about 'Generation IV' and Fusion reactors.
* {{cite web |url=http://memagazine.asme.org/Articles/2011/December/Nuclear_Power_After_Fukushima.cfm |title=Nuclear Power After Fukushima |author=Gail H. Marcus |date=December 2011 |work=Mechanical Engineering (the magazine of [[ASME]]) |accessdate=23 January 2012}} "In the wake of a severe plant accident, advanced reactor designs are getting renewed attention."
* [http://www.itheo.org/ International Thorium Energy Organisation - www.IThEO.org]
* [http://www.ithec.org/ International Thorium Energy Committee - iThEC]

{{Nuclear fission reactors}}

[[Category:Nuclear power reactor types]]
[[Category:Idaho National Laboratory]]

Benutzer:Snackroeg/Kernreaktoren der Generation 5

2016-12-05T17:25:05Z

Boundarylayer: /* Lead-cooled fast reactor (LFR) */ the table doesn't see appropriate there either

[[File:GenIVRoadmap-en.svg|thumb|480px|Nuclear Energy Systems Deployable no later than 2030 and offering significant advances in sustainability, safety and reliability, and economics]]

'''Generation IV reactors''' ('''Gen IV''') are a set of [[nuclear reactor]] designs currently being researched for commercial applications by the Generation IV International Forum, with [[Technology readiness level]]s varying between the level requiring a demonstration, to economical competitive implementation. They are motivated by a variety of goals including improved safety, sustainability, efficiency, and cost.

Most of these designs are generally not expected to be available for commercial construction before 2030–40.<ref name="Generation IV">[http://www.world-nuclear.org/info/Nuclear-Fuel-Cycle/Power-Reactors/Generation-IV-Nuclear-Reactors/]</ref> Presently the majority of reactors in operation around the world are considered [[Generation II reactor|second generation reactor]] systems, as the vast majority of the [[Generation I reactor|first-generation]] systems were retired some time ago, and there are only a dozen or so [[Generation III reactor]]s in operation (2014). [[Nuclear reactor#Generation V+ reactors|Generation V reactors]] refer to reactors that are purely theoretical and are therefore not yet considered feasible in the short term, resulting in limited [[R&D]] funding.

== History ==
The Generation IV International Forum (GIF) is "a co-operative international endeavour which was set up to carry out the research and development needed to establish the feasibility and performance capabilities of the next generation nuclear energy systems."<ref>{{Cite web|url=https://www.gen-4.org/gif/jcms/c_9260/public|title=GIF Portal - Home - Public|website=www.gen-4.org|access-date=2016-07-25}}</ref> It was founded in 2001. There are currently ten active members of the Generation IV International Forum (GIF): [[Canada]], [[China]], the [[European Atomic Energy Community]] (Euratom), [[France]], [[Japan]], [[Russia]], [[South Africa]], [[South Korea]], [[Switzerland]], and the [[United States]]. The non-active members are [[Argentina]], [[Brazil]], and the [[United Kingdom]].<ref name="gen-4">{{cite web|url=https://www.gen-4.org/gif/jcms/c_9492/members|title=GIF Membership|website=gen-4.org|accessdate=28 October 2014}}</ref> Switzerland joined in 2002, Euratom in 2003, and China and Russia in 2006. The remaining countries (excluding Australia) were founding members.<ref name="gen-4" />

The 36th GIF meeting in [[Brussels]] was held in November 2013.<ref>{{cite web|url=http://www.energy.gov/ne/articles/generation-iv-international-forum-updates-technology-roadmap-and-builds-future|title=generation IV international forum updates technology roadmap and builds future. DOE}}</ref><ref>{{cite web|url=http://events.r20.constantcontact.com/register/event?llr=mscrkjkab&oeidk=a07e7melf609716b2c6|title=The Generation IV international forum holds their 36th meeting on Monday 18th Nov 2013 in Brussels.}}</ref> The ''Technology Roadmap Update for Generation IV Nuclear Energy Systems'' was published in January 2014 which details R&D objectives for the next decade.<ref>[https://web.archive.org/web/20140625102915/https://www.gen-4.org/gif/upload/docs/application/pdf/2014-03/gif-tru2014.pdf Technology Roadmap Update for Generation IV Nuclear Energy Systems]</ref> A breakdown of the reactor designs being researched by each forum member has been made available.<ref>[https://web.archive.org/web/20140708023538/https://www.gen-4.org/gif/upload/docs/application/pdf/2014-03/gif_overview_presentation_v9_final3_web.pdf Generation IV International Forum, overview, John E. Kelly, page 15]</ref>

[[Nuclear power in Australia|Australia]] joined the forum in 2016.<ref>http://archive.is/22e5F</ref>

== Reactor types ==
Many reactor types were considered initially; however, the list was downsized to focus on the most promising technologies and those that could most likely meet the goals of the Gen IV initiative.<ref name="Generation IV"/> Three systems are nominally [[thermal reactor]]s and three are [[fast reactor]]s. The Very High Temperature Reactor (VHTR) is also being researched for potentially providing high quality process heat for [[thermochemical cycle|hydrogen production]]. The fast reactors offer the possibility of burning [[actinides]] to further reduce waste and of being able to "[[breeder reactor|breed more fuel]]" than they consume. These systems offer significant advances in sustainability, safety and reliability, economics, proliferation resistance (depending on perspective) and physical protection.

=== Thermal reactors ===
A [[Thermal-neutron reactor|thermal reactor]] is a [[nuclear reactor]] that uses slow or [[thermal neutrons]]. A [[neutron moderator]] is used to slow the [[neutron]]s emitted by fission to make them more likely to be captured by the fuel.

==== Very-high-temperature reactor (VHTR) ====
[[File:Very High Temperature Reactor.svg|right|thumb|Very-High-Temperature Reactor (VHTR)]]
{{Main article|Very high temperature reactor}}
{{see also|Fort St. Vrain Generating Station|HTTR|HTR-10}}
The '''very high temperature reactor''' concept uses a [[graphite]]-moderated core with a once-through [[uranium]] fuel cycle, using helium or molten salt as the [[Very high temperature reactor#Coolant|coolant]]. This reactor design envisions an outlet temperature of 1,000 °C. The reactor core can be either a prismatic-block or a [[pebble bed reactor]] design. The high temperatures enable applications such as process heat or [[hydrogen]] production via the thermochemical [[Sulfur-iodine cycle|iodine-sulfur]] process. It would also be [[Passive nuclear safety|passively safe]].

The planned construction of the first VHTR, the South African PBMR ([[pebble bed modular reactor]]), lost government funding in February, 2010.<ref>[http://www.powergenworldwide.com/index/display/articledisplay/6322207443/articles/power-engineering-international/volume-18/Issue_3/regulars/world-news/INTERNATIONAL.html South Africa to stop funding Pebble Bed nuclear reactor]</ref> A pronounced increase of costs and concerns about possible unexpected technical problems had discouraged potential investors and customers.

The [[Peoples Republic of China]] began construction of a 200-MW High Temperature Pebble bed reactor in 2012 as a successor to its [[HTR-10]].<ref>[http://www.nucnet.org/all-the-news/2013/01/07/china-begins-construction-of-first-generation-iv-htr-pm-unit Nucnet Report: 'China Begins Construction of First Generation IV HTR-PM Unit', 7 January 2013]</ref>

Also in 2012, as part of the [[Next Generation Nuclear Plant]] competition, [[Idaho National Laboratory]] approved a design similar to [[Areva]]'s prismatic block [http://us.areva.com/EN/home-3225/areva-inc-areva-htgr.html Antares reactor] as the chosen [[HTGR]] to be deployed as a prototype by 2021. It was in competition with [[General Atomics]]' [[Gas turbine modular helium reactor]] and [[Westinghouse Electric Company|Westinghouse]]'s [[Pebble Bed Modular Reactor]].<ref name="World nuclear news">{{cite web|url=http://www.world-nuclear-news.org/NN-Areva_modular_reactor_selected_for_NGNP_development-1502124.html|title=INL approves Antares design}}</ref>

==== Molten-salt reactor (MSR) ====
[[File:Molten Salt Reactor.svg|right|thumb|Molten Salt Reactor (MSR)]]
{{Main article|Molten salt reactor}}
{{see also|Liquid fluoride thorium reactor}}
A '''molten salt reactor'''<ref name="Roadmap"/> is a type of [[nuclear reactor]] where the primary [[coolant]], or even the fuel itself is a molten salt mixture. There have been many designs put forward for this type of reactor and a few prototypes built. The early concepts and many current ones rely on [[nuclear fuel]] dissolved in the molten [[fluoride]] salt as [[uranium tetrafluoride]] (UF4) or [[thorium tetrafluoride]] (ThF4). The fluid would reach [[Nuclear reactor physics#Criticality|criticality]] by flowing into a [[graphite]] core which would also serve as the [[neutron moderator|moderator]]. Many current concepts rely on fuel that is dispersed in a graphite matrix with the molten salt providing low pressure, high temperature cooling.

The Gen IV MSR is more accurately termed an [[epithermal neutron|epithermal reactor]] than a thermal reactor due to the average speed of the neutrons that would cause the fission events within its fuel being faster than [[thermal neutron]]s.<ref>{{cite web |url=https://inlportal.inl.gov/portal/server.pt?open=514&objID=1361&parentname=CommunityPage&parentid=10&mode=2&in_hi_userid=200&cached=true |title=Idaho National Laboratory detailing some current efforts at developing Gen. IV reactors}}</ref>

The principle of a MSR can be used for thermal, epithermal and fast reactors. Since 2005 the focus has moved towards a fast spectrum MSR (MSFR).<ref>H. Boussier, S. Delpech, V. Ghetta et Al. : The Molten Salt Reactor (MSR) in Generation IV: Overview and Perspectives, GIF SYMPOSIUM PROCEEDINGS/2012 ANNUAL REPORT, NEA No. 7141, pp95 [https://www.gen-4.org/gif/jcms/c_44720/annual-reports]
</ref>

While most MSR designs being pursued are largely derived from the 1960s [[Molten-Salt Reactor Experiment]](MSRE), variants of molten salt technology include the conceptual ''[[Dual fluid reactor]]'' which is being designed with lead as a cooling medium but molten salt fuel, commonly as the metal chloride e.g [[Plutonium(III) chloride]], to aid in greater "nuclear waste" closed-fuel cycle capabilities.
Other notable approaches differing substantially from those with MSRE [[pedigree]] include the ''[[Stable Salt Reactor]]''(SSR) concept promoted by MOLTEX, which encases the molten salt in hundreds of the common solid [[fuel rod]]s that are already well established in the nuclear industry. This latter British design was found to be the most competitive for [[Small modular reactor]] development by a British based consultancy firm ''Energy Process Development'' in 2015.<ref>[http://www.daretothink.org/europe-moltex-stable-salt-reactor/ Europe: Moltex’ Stable Salt Reactor]</ref><ref>[http://analysis.nuclearenergyinsider.com/moltex-energy-sees-uk-canada-smr-licensing-springboard-asia Moltex Energy sees UK, Canada SMR licensing as springboard to Asia Jun 28, 2016]</ref>

==== Supercritical-water-cooled reactor (SCWR) ====
[[File:Supercritical-Water-Cooled Reactor.svg|right|thumb|Supercritical-Water-Cooled Reactor (SCWR)]]
{{Main article|Supercritical water reactor}}
The '''supercritical water reactor''' (SCWR)<ref name="Roadmap"/> is a [[reduced moderation water reactor]] concept that, due to the average speed of the neutrons that would cause the fission events within the fuel being faster than [[thermal neutron]]s, it is more accurately termed an [[epithermal neutron|epithermal reactor]] than a thermal reactor. It uses [[supercritical fluid|supercritical water]] as the working fluid. SCWRs are basically [[light water reactor]]s (LWR) operating at higher pressure and temperatures with a direct, once-through heat exchange cycle. As most commonly envisioned, it would operate on a direct cycle, much like a boiling water reactor ([[BWR]]), but since it uses supercritical water (not to be confused with [[Critical mass (nuclear)|critical mass]]) as the working fluid, it would have only one water phase present, which makes the supercritical heat exchange method more similar to a pressurized water reactor ([[Pressurized water reactor|PWR]]). It could operate at much higher temperatures than both current PWRs and BWRs.

Supercritical water-cooled reactors (SCWRs) are promising advanced nuclear systems because of their high [[thermal efficiency]] (i.e., about 45% vs. about 33% efficiency for current LWRs) and considerable plant simplification.

The main mission of the SCWR is generation of low-cost [[electricity]]. It is built upon two proven technologies, LWRs, which are the most commonly deployed power generating reactors in the world, and superheated [[fossil fuel]] fired [[boiler]]s, a large number of which are also in use around the world. The SCWR concept is being investigated by 32 organizations in 13 countries.{{citation needed|date=October 2012}}

A SCWR Design under development is the [[VVER]]-1700/393 (VVER-SCWR or VVER-SKD) — a Russian Supercritical-water-cooled reactor with double-inlet-core and a [[breeder reactor|breeding ratio]] of 0.95.<ref name="powertecrussia.com">{{cite web |url=http://www.powertecrussia.com/blog/tag/nuclear-power/ |title=Technology Developments & Plant Efficiency for the Russian Nuclear Power Generation Market Wednesday |date=March 24, 2010}}</ref>

=== Fast reactors ===
A [[Fast-neutron reactor|fast reactor]] directly uses the fast neutrons emitted by fission, without moderation. Unlike thermal neutron reactors, fast neutron reactors can be configured to "'''burn'''", or fission, all [[actinides]], and given enough time, therefore drastically reduce the actinides fraction in [[spent nuclear fuel]] produced by the present world fleet of thermal neutron [[light water reactor]]s, thus closing the [[nuclear fuel cycle]]. Alternatively, if configured differently, they can also [[breeder reactor|'''breed''']] more actinide fuel than they consume.

==== Gas-cooled fast reactor (GFR) ====
[[File:Gas-Cooled Fast Reactor Schemata.svg|right|thumb|Gas-Cooled Fast Reactor (GFR)]]
{{Main article|Gas-cooled fast reactor}}
The '''gas-cooled fast reactor''' (GFR)<ref name="Roadmap"/> system features a fast-neutron spectrum and closed fuel cycle for efficient conversion of [[Fertile material|fertile uranium]] and management of actinides. The reactor is [[helium]]-cooled and with an outlet temperature of 850 °C it is an evolution of the [[very-high-temperature reactor]] (VHTR) to a more sustainable fuel cycle. It will use a direct [[Brayton cycle]] [[Closed-cycle gas turbine|gas turbine]] for high thermal efficiency. Several fuel forms are being considered for their potential to operate at very high temperatures and to ensure an excellent retention of [[Nuclear fission|fission]] products: composite [[ceramic]] fuel, advanced fuel particles, or ceramic clad elements of actinide compounds. Core configurations are being considered based on pin- or plate-based fuel assemblies or prismatic blocks.

The European Sustainable Nuclear Industrial Initiative is funding three Generation IV reactor systems, one of which is a gas-cooled fast reactor, called ''Allegro'', 100 MW(t), which will be built in a central or eastern European country with construction expected to begin in 2018.<ref name="euronuclear.org">{{cite web |url=https://www.euronuclear.org/1-information/news/Gen-IV.htm |title=The European Sustainable Nuclear Industrial Initiative (ESNII) will support three Generation IV reactor systems: a sodium-cooled fast reactor, or SFR, called ''Astrid'' that is proposed by France; a gas-cooled fast reactor, GFR, called ''Allegro'' supported by central and eastern Europe; and a lead-cooled fast reactor, LFR, technology pilot called ''Myrrha'' that is proposed by Belgium.}}</ref> The central European [[Visegrád Group]] are committed to pursuing the technology.<ref>{{cite web |url=http://www.alphagalileo.org/ViewItem.aspx?ItemId=133111&CultureCode=en |title=The V4G4 Centre of Excellence for performing joint research, development and innovation in the field of Generation-4 (G4) nuclear reactors have been established. 20 July 2013 National Center for Nuclear Research (NCBJ]}}</ref> In 2013 German, British, and French institutes finished a 3-year collaboration study on the follow on industrial scale design, known as ''GoFastR''.<ref>{{cite web |url=http://www.ist-world.org/ProjectDetails.aspx?ProjectId=5cb8f3f283574cc6b2bdbf72533172d8 |title=the European Gas cooled Fast Reactor.}}</ref> They were funded by the EU's 7th FWP [[framework programme]], with the goal of making a sustainable VHTR.<ref>{{cite web |url=http://www.2020-horizon.com/GOFASTR-European-Gas-Cooled-Fast-Reactor%28GOFASTR%29-s312.html |title=The GOFASTR research program}}</ref>

==== Sodium-cooled fast reactor (SFR) ====
[[File:Sodium-Cooled Fast Reactor Schemata.svg|right|thumb|Pool design Sodium-Cooled Fast Reactor (SFR)]]
{{Main article|Sodium-cooled fast reactor}}
{{see also|Prototype Fast Breeder Reactor|Experimental Breeder Reactor II|S-PRISM|BN-800 reactor|Toshiba 4S}}

In India, the [[Fast Breeder Test Reactor]] reached criticality in October 1985. In September 2002, fuel burn-up in the FBTR for the first time reached the 100,000 megawatt-days per metric ton uranium (MWd/MTU) mark. This is considered an important milestone in breeder reactor technology. Using the experience gained from the operation of the FBTR, the [[Prototype Fast Breeder Reactor]], a 500 MWe Sodium cooled fast reactor is being built at a cost of INR 5,677 crores (~US$900 million) and is expected to be critical by June 2016. The PFBR will be followed by six more Commercial Fast Breeder Reactors (CFBRs) of 600 MWe each.

The SFR<ref name="Roadmap"/> is a project that builds on two closely related existing projects, the liquid metal [[Breeder reactor#Fast breeder reactor|fast breeder reactor]] and the [[integral fast reactor]].

The goals are to increase the efficiency of uranium usage by [[breeder reactor|breeding]] plutonium and eliminating the need for [[transuranic]] isotopes ever to leave the site. The reactor design uses an unmoderated core running on [[fast neutron]]s, designed to allow any transuranic isotope to be consumed (and in some cases used as fuel). In addition to the benefits of removing the long [[half-life]] transuranics from the waste cycle, the SFR fuel expands when the reactor overheats, and the chain reaction automatically slows down. In this manner, it is passively safe.<ref>{{cite web |url=http://www.ne.anl.gov/About/hn/logos-winter02-psr.shtml|title=Passively safe reactors rely on nature to keep them cool|author=David Baurac}}</ref>

The SFR reactor concept is cooled by liquid [[sodium]] and fueled by a metallic alloy of uranium and [[plutonium]] or [[spent nuclear fuel]], the "nuclear waste" of [[light water reactor]]s. The SFR fuel is contained in steel cladding with liquid sodium filling in the space between the clad elements which make up the fuel assembly. One of the design challenges of an SFR is the risks of handling sodium, which reacts explosively if it comes into contact with water. However, the use of liquid metal instead of water as coolant allows the system to work at atmospheric pressure, reducing the risk of leakage.

The European Sustainable Nuclear Industrial Initiative is funding three Generation IV reactor systems, one of which is a sodium-cooled fast reactor, called ''[[ASTRID (reactor)|ASTRID]]'', Advanced Sodium Technical Reactor for Industrial Demonstration, [[Areva]], [[Commissariat à l'énergie atomique et aux énergies alternatives|CEA]] and [[Électricité de France|EDF]] are leading the design with British collaboration.<ref>{{cite web |url=http://www.power-eng.com/articles/2010/11/areva--cea-secure.html |title=Areva, CEA secure EUR650m funding to develop ASTRID sodium-cooled Generation IV reactor 11/11/2010}}</ref><ref>{{cite web |url=http://www.powermag.com/uk-and-france-sign-landmark-civil-nuclear-cooperation-agreement/ |title=UK and France Sign Landmark Civil Nuclear Cooperation Agreement 02/22/2012 . POWERnews}}</ref> Astrid will be rated about 600 MWe and is proposed to be built in France, near to the [[Phénix]] reactor. A final decision in construction is to be made in 2019<ref name="euronuclear.org"/>

The [[China|PRC]]'s first commercial-scale, 800 MWe, fast neutron reactor, to be situated near [[Sanming]] in [[Fujian province]] will be a SFR. In 2009 an agreement was signed that would entail the Russian [[BN-800 reactor]] design to be sold to the PRC once it is completed, this would be the first time commercial-scale fast neutron reactors have ever been exported.<ref>{{cite web |url=http://www.world-nuclear-news.org/C-Joint_venture_launched_for_Chinese_fast_reactor-3004104.html |title=Joint venture launched for Chinese fast reactor}}</ref> The BN-800 reactor became operational in 2014.

The 400 MWe [[Fast Flux Test Facility]] operated successfully for ten years at the Hanford site in Washington State.

The 20 MWe [[EBR II]] operated successfully for over thirty years at the Idaho National Laboratory, until it was shut down in 1994.

==== Lead-cooled fast reactor (LFR) ====
[[File:Lead-Cooled Fast Reactor Schemata.svg|right|thumb|Lead-Cooled Fast Reactor (LFR)]]
{{Main article|Lead-cooled fast reactor}}
{{See also|MYRRHA}}
The '''lead-cooled fast reactor'''<ref name="Roadmap">{{cite journal| year=2002 | title=A Technology Roadmap for Generation IV Nuclear Energy Systems | last=US DOE Nuclear Energy Research Advisory Committee |volume=GIF-002-00|url=http://nuclear.energy.gov/genIV/documents/gen_iv_roadmap.pdf}}</ref> features a fast-neutron-spectrum [[lead]] or [[lead]]/[[bismuth]] [[eutectic]] ([[Lead-bismuth eutectic|LBE]]) liquid-metal-cooled reactor with a closed [[Nuclear fuel cycle|fuel cycle]]. Options include a range of plant ratings, including a "battery" of 50 to 150 MW of electricity that features a very long refueling interval, a modular system rated at 300 to 400 MW, and a large monolithic plant option at 1,200 MW. (The term ''battery'' refers to the long-life, factory-fabricated core, not to any provision for electrochemical energy conversion.) The fuel is metal or nitride-based containing [[Fertile material|fertile uranium]] and [[transuranic]]s. The LFR is cooled by natural [[convection]] with a reactor outlet coolant temperature of 550 °C, possibly ranging up to 800 °C with advanced materials. The higher temperature enables the production of [[Thermochemical cycle|hydrogen by thermochemical processes]].

The European Sustainable Nuclear Industrial Initiative is funding three Generation IV reactor systems, one of which is a lead-cooled fast reactor that is also an [[Subcritical reactor|accelerator-driven sub-critical]] reactor, called ''[[MYRRHA]]'', 100 MW(t), which will be built in [[Belgium]] with construction expected to begin after 2014 and the industrial scale version, known as ''Alfred'', slated to be constructed sometime after 2017. A reduced-power model of Myrrha called ''Guinevere'' was started up at [[Mol, Belgium|Mol]] in March 2009.<ref name="euronuclear.org"/> In 2012 the research team reported that Guinevere was operational.<ref>{{cite news|last1=Hellemans|first1=Alexander|title=Reactor-Accelerator Hybrid Achieves Successful Test Run|url=http://news.sciencemag.org/physics/2012/01/reactor-accelerator-hybrid-achieves-successful-test-run|accessdate=29 December 2014|work=Science Insider|date=12 January 2012}}</ref>

Two other lead-cooled fast reactors under development are the SVBR-100, a modular 100 MWe lead-bismuth cooled fast neutron reactor concept designed by OKB [[Gidropress]] in Russia and the [[BREST (Reactor)|BREST-OD-300]] (Lead-cooled fast reactor) 300 MWe, to be developed after the SVBR-100, and built over 2016-20, it will dispense with the [[Uranium-238|fertile blanket]] around the core and will supersede the sodium cooled [[BN-600 reactor]] design, to purportedly give enhanced proliferation resistance.<ref name="powertecrussia.com"/>

== Advantages and disadvantages ==
Relative to current nuclear power plant technology, the claimed benefits for 4th generation reactors include:
* Nuclear waste that remains radioactive for a few centuries instead of millennia<ref>{{cite web |title=Strategies to Address Global Warming |url=http://www.columbia.edu/~jeh1/mailings/2009/20090713_Strategies.pdf}}</ref>
* 100-300 times more energy yield from the same amount of nuclear fuel<ref>{{cite web |title=4th Generation Nuclear Power |url=http://www.ossfoundation.us/projects/energy/nuclear}}</ref>
* Broader range of fuels, and even unencapsulated raw fuels (non-pebble [[Molten Salt Reactor|MSR]], [[LFTR]]).
* In some reactors, the ability to consume existing nuclear waste in the production of electricity, that is, a Closed [[nuclear fuel cycle]]. This strengthens the argument to deem [[nuclear power as renewable energy]].
* Improved operating safety features, such as (depending on design) avoidance of pressurized operation, automatic passive (unpowered, uncommanded) reactor shutdown, avoidance of water cooling and the associated risks of loss of water (leaks or boiling) and hydrogen generation/explosion and contamination of coolant water.

Nuclear reactors do not emit CO2 during operation, although like all [[low carbon power]] sources, the mining and construction phase can result in CO2 emissions, if energy sources which are not carbon neutral (such as fossil fuels), or CO2 emitting cements are used during the construction process.
A 2012 [[Yale University]] review published in the Journal of Industrial Ecology analyzing {{CO2}} [[life cycle assessment]] (LCA) emissions from [[nuclear power]] determined that:<ref name="Warner + Heath, JoIE">Warner, Ethan S.; Heath, Garvin A. [http://onlinelibrary.wiley.com/doi/10.1111/j.1530-9290.2012.00472.x/full Life Cycle Greenhouse Gas Emissions of Nuclear Electricity Generation: Systematic Review and Harmonization], ''Journal of Industrial Ecology'', [[Yale University]], published online April 17, 2012, doi: 10.1111/j.1530-9290.2012.00472.x.</ref>
{{Quote|''"The collective LCA literature indicates that life cycle [[Greenhouse gas|GHG]] [ greenhouse gas ] emissions from nuclear power are only a fraction of traditional fossil sources and comparable to renewable technologies."''}}
Although the paper primarily dealt with data from [[Generation II reactor]]s, and did not analyze the {{CO2}} emissions by 2050 of the presently under construction [[Generation III reactor]]s, it did summarize the Life Cycle Assessment findings of in development reactor technologies.''{{Quote|FBRs ''[ [[Fast Breeder Reactor]]s ]'' have been evaluated in the LCA literature. The limited literature that evaluates this potential future technology reports [[median]] life cycle GHG emissions... similar to or lower than LWRs[ Gen II [[light water reactor]]s ] and purports to consume little or no [[uranium market|uranium ore]].}}

A specific risk of the sodium-cooled fast reactor is related to using metallic sodium as a coolant. In case of a breach, sodium explosively reacts with water. Fixing breaches may also prove dangerous, as the cheapest noble gas [[argon]] is also used to prevent sodium oxidation. Argon, like helium, can displace oxygen in the air and can pose [[hypoxia (environmental)|hypoxia]] concerns, so workers may be exposed to this additional risk. This is a pertinent problem as can be testified by the events at the [[LMFBR|loop type]] [[Monju Nuclear Power Plant|Prototype Fast Breeder Reactor Monju]] at Tsuruga, Japan.<ref>{{cite news |title=Japan Strains to Fix a Reactor Damaged Before Quake |url=http://www.nytimes.com/2011/06/18/world/asia/18japan.html | work=The New York Times | first=Hiroko |last=Tabuchi |date=17 June 2011}}</ref>
Using lead or molten salts mitigates this problem by making the coolant less reactive and allowing a high freezing temperature and low pressure in case of a leak. Disadvantages of lead compared to sodium are much higher viscosity, much higher density, lower heat capacity, and more radioactive neutron activation products.

In many cases, there is already a large amount of experience built up with numerous proof of concept Gen IV designs. For example, the reactors at [[Fort St. Vrain Generating Station]] and [[HTR-10]] are similar to the proposed Gen IV [[VHTR]] designs, and the [[LMFBR|pool type]] [[EBR-II]], [[Phénix]] and [[BN-600]] reactor are similar to the proposed pool type Gen IV Sodium Cooled Fast reactors being designed.

== See also ==
{{colbegin|3}}
* [[Nuclear reactor]]
* [[Nuclear material]]
* [[Nuclear physics]]
* [[List of reactor types#Reactor types|List of reactor types]]
* [[Generation II reactor]]
* [[Generation III reactor]]
* [[Integral Fast Reactor]]
* [[Liquid fluoride thorium reactor]]
* [[Breeder reactor]]
* [[Small modular reactor]]
{{colend}}

==References==
{{Reflist|30em}}

== External links ==
* [https://inlportal.inl.gov/portal/server.pt?open=514&objID=1361&parentname=CommunityPage&parentid=10&mode=2&in_hi_userid=200&cached=true Article from Idaho National Laboratory detailing some current efforts at developing Gen. IV reactors.]
* [http://www.gen-4.org/ Generation IV International Forum (GIF)]
* [http://nuclear.energy.gov/genIV/neGenIV1.html U.S. Department of Energy Office of Nuclear Energy, Science and Technology]
* [http://www.engr.utk.edu/nuclear/colloquia/slides/Gen%20IV%20U-Tenn%20Presentation.pdf Gen IV presentation]
* [http://www.ecology.at/ecology/files/pr577_1.pdf Science or Fiction - Is there a Future for Nuclear?] (Nov. 2007) - A publication from the Austrian [[Ecology Institute (Austria)|Ecology Institute]] about 'Generation IV' and Fusion reactors.
* {{cite web |url=http://memagazine.asme.org/Articles/2011/December/Nuclear_Power_After_Fukushima.cfm |title=Nuclear Power After Fukushima |author=Gail H. Marcus |date=December 2011 |work=Mechanical Engineering (the magazine of [[ASME]]) |accessdate=23 January 2012}} "In the wake of a severe plant accident, advanced reactor designs are getting renewed attention."
* [http://www.itheo.org/ International Thorium Energy Organisation - www.IThEO.org]
* [http://www.ithec.org/ International Thorium Energy Committee - iThEC]

{{Nuclear fission reactors}}

[[Category:Nuclear power reactor types]]
[[Category:Idaho National Laboratory]]

Benutzer:Snackroeg/Kernreaktoren der Generation 5

2016-12-05T17:24:03Z

Boundarylayer: /* Reactor types */ This user generated table is inappropriately placed to high up in the article, in a place well before many readers even learn what a "VHTR, SFR & MSR" etc. are!

[[File:GenIVRoadmap-en.svg|thumb|480px|Nuclear Energy Systems Deployable no later than 2030 and offering significant advances in sustainability, safety and reliability, and economics]]

'''Generation IV reactors''' ('''Gen IV''') are a set of [[nuclear reactor]] designs currently being researched for commercial applications by the Generation IV International Forum, with [[Technology readiness level]]s varying between the level requiring a demonstration, to economical competitive implementation. They are motivated by a variety of goals including improved safety, sustainability, efficiency, and cost.

Most of these designs are generally not expected to be available for commercial construction before 2030–40.<ref name="Generation IV">[http://www.world-nuclear.org/info/Nuclear-Fuel-Cycle/Power-Reactors/Generation-IV-Nuclear-Reactors/]</ref> Presently the majority of reactors in operation around the world are considered [[Generation II reactor|second generation reactor]] systems, as the vast majority of the [[Generation I reactor|first-generation]] systems were retired some time ago, and there are only a dozen or so [[Generation III reactor]]s in operation (2014). [[Nuclear reactor#Generation V+ reactors|Generation V reactors]] refer to reactors that are purely theoretical and are therefore not yet considered feasible in the short term, resulting in limited [[R&D]] funding.

== History ==
The Generation IV International Forum (GIF) is "a co-operative international endeavour which was set up to carry out the research and development needed to establish the feasibility and performance capabilities of the next generation nuclear energy systems."<ref>{{Cite web|url=https://www.gen-4.org/gif/jcms/c_9260/public|title=GIF Portal - Home - Public|website=www.gen-4.org|access-date=2016-07-25}}</ref> It was founded in 2001. There are currently ten active members of the Generation IV International Forum (GIF): [[Canada]], [[China]], the [[European Atomic Energy Community]] (Euratom), [[France]], [[Japan]], [[Russia]], [[South Africa]], [[South Korea]], [[Switzerland]], and the [[United States]]. The non-active members are [[Argentina]], [[Brazil]], and the [[United Kingdom]].<ref name="gen-4">{{cite web|url=https://www.gen-4.org/gif/jcms/c_9492/members|title=GIF Membership|website=gen-4.org|accessdate=28 October 2014}}</ref> Switzerland joined in 2002, Euratom in 2003, and China and Russia in 2006. The remaining countries (excluding Australia) were founding members.<ref name="gen-4" />

The 36th GIF meeting in [[Brussels]] was held in November 2013.<ref>{{cite web|url=http://www.energy.gov/ne/articles/generation-iv-international-forum-updates-technology-roadmap-and-builds-future|title=generation IV international forum updates technology roadmap and builds future. DOE}}</ref><ref>{{cite web|url=http://events.r20.constantcontact.com/register/event?llr=mscrkjkab&oeidk=a07e7melf609716b2c6|title=The Generation IV international forum holds their 36th meeting on Monday 18th Nov 2013 in Brussels.}}</ref> The ''Technology Roadmap Update for Generation IV Nuclear Energy Systems'' was published in January 2014 which details R&D objectives for the next decade.<ref>[https://web.archive.org/web/20140625102915/https://www.gen-4.org/gif/upload/docs/application/pdf/2014-03/gif-tru2014.pdf Technology Roadmap Update for Generation IV Nuclear Energy Systems]</ref> A breakdown of the reactor designs being researched by each forum member has been made available.<ref>[https://web.archive.org/web/20140708023538/https://www.gen-4.org/gif/upload/docs/application/pdf/2014-03/gif_overview_presentation_v9_final3_web.pdf Generation IV International Forum, overview, John E. Kelly, page 15]</ref>

[[Nuclear power in Australia|Australia]] joined the forum in 2016.<ref>http://archive.is/22e5F</ref>

== Reactor types ==
Many reactor types were considered initially; however, the list was downsized to focus on the most promising technologies and those that could most likely meet the goals of the Gen IV initiative.<ref name="Generation IV"/> Three systems are nominally [[thermal reactor]]s and three are [[fast reactor]]s. The Very High Temperature Reactor (VHTR) is also being researched for potentially providing high quality process heat for [[thermochemical cycle|hydrogen production]]. The fast reactors offer the possibility of burning [[actinides]] to further reduce waste and of being able to "[[breeder reactor|breed more fuel]]" than they consume. These systems offer significant advances in sustainability, safety and reliability, economics, proliferation resistance (depending on perspective) and physical protection.

=== Thermal reactors ===
A [[Thermal-neutron reactor|thermal reactor]] is a [[nuclear reactor]] that uses slow or [[thermal neutrons]]. A [[neutron moderator]] is used to slow the [[neutron]]s emitted by fission to make them more likely to be captured by the fuel.

==== Very-high-temperature reactor (VHTR) ====
[[File:Very High Temperature Reactor.svg|right|thumb|Very-High-Temperature Reactor (VHTR)]]
{{Main article|Very high temperature reactor}}
{{see also|Fort St. Vrain Generating Station|HTTR|HTR-10}}
The '''very high temperature reactor''' concept uses a [[graphite]]-moderated core with a once-through [[uranium]] fuel cycle, using helium or molten salt as the [[Very high temperature reactor#Coolant|coolant]]. This reactor design envisions an outlet temperature of 1,000 °C. The reactor core can be either a prismatic-block or a [[pebble bed reactor]] design. The high temperatures enable applications such as process heat or [[hydrogen]] production via the thermochemical [[Sulfur-iodine cycle|iodine-sulfur]] process. It would also be [[Passive nuclear safety|passively safe]].

The planned construction of the first VHTR, the South African PBMR ([[pebble bed modular reactor]]), lost government funding in February, 2010.<ref>[http://www.powergenworldwide.com/index/display/articledisplay/6322207443/articles/power-engineering-international/volume-18/Issue_3/regulars/world-news/INTERNATIONAL.html South Africa to stop funding Pebble Bed nuclear reactor]</ref> A pronounced increase of costs and concerns about possible unexpected technical problems had discouraged potential investors and customers.

The [[Peoples Republic of China]] began construction of a 200-MW High Temperature Pebble bed reactor in 2012 as a successor to its [[HTR-10]].<ref>[http://www.nucnet.org/all-the-news/2013/01/07/china-begins-construction-of-first-generation-iv-htr-pm-unit Nucnet Report: 'China Begins Construction of First Generation IV HTR-PM Unit', 7 January 2013]</ref>

Also in 2012, as part of the [[Next Generation Nuclear Plant]] competition, [[Idaho National Laboratory]] approved a design similar to [[Areva]]'s prismatic block [http://us.areva.com/EN/home-3225/areva-inc-areva-htgr.html Antares reactor] as the chosen [[HTGR]] to be deployed as a prototype by 2021. It was in competition with [[General Atomics]]' [[Gas turbine modular helium reactor]] and [[Westinghouse Electric Company|Westinghouse]]'s [[Pebble Bed Modular Reactor]].<ref name="World nuclear news">{{cite web|url=http://www.world-nuclear-news.org/NN-Areva_modular_reactor_selected_for_NGNP_development-1502124.html|title=INL approves Antares design}}</ref>

==== Molten-salt reactor (MSR) ====
[[File:Molten Salt Reactor.svg|right|thumb|Molten Salt Reactor (MSR)]]
{{Main article|Molten salt reactor}}
{{see also|Liquid fluoride thorium reactor}}
A '''molten salt reactor'''<ref name="Roadmap"/> is a type of [[nuclear reactor]] where the primary [[coolant]], or even the fuel itself is a molten salt mixture. There have been many designs put forward for this type of reactor and a few prototypes built. The early concepts and many current ones rely on [[nuclear fuel]] dissolved in the molten [[fluoride]] salt as [[uranium tetrafluoride]] (UF4) or [[thorium tetrafluoride]] (ThF4). The fluid would reach [[Nuclear reactor physics#Criticality|criticality]] by flowing into a [[graphite]] core which would also serve as the [[neutron moderator|moderator]]. Many current concepts rely on fuel that is dispersed in a graphite matrix with the molten salt providing low pressure, high temperature cooling.

The Gen IV MSR is more accurately termed an [[epithermal neutron|epithermal reactor]] than a thermal reactor due to the average speed of the neutrons that would cause the fission events within its fuel being faster than [[thermal neutron]]s.<ref>{{cite web |url=https://inlportal.inl.gov/portal/server.pt?open=514&objID=1361&parentname=CommunityPage&parentid=10&mode=2&in_hi_userid=200&cached=true |title=Idaho National Laboratory detailing some current efforts at developing Gen. IV reactors}}</ref>

The principle of a MSR can be used for thermal, epithermal and fast reactors. Since 2005 the focus has moved towards a fast spectrum MSR (MSFR).<ref>H. Boussier, S. Delpech, V. Ghetta et Al. : The Molten Salt Reactor (MSR) in Generation IV: Overview and Perspectives, GIF SYMPOSIUM PROCEEDINGS/2012 ANNUAL REPORT, NEA No. 7141, pp95 [https://www.gen-4.org/gif/jcms/c_44720/annual-reports]
</ref>

While most MSR designs being pursued are largely derived from the 1960s [[Molten-Salt Reactor Experiment]](MSRE), variants of molten salt technology include the conceptual ''[[Dual fluid reactor]]'' which is being designed with lead as a cooling medium but molten salt fuel, commonly as the metal chloride e.g [[Plutonium(III) chloride]], to aid in greater "nuclear waste" closed-fuel cycle capabilities.
Other notable approaches differing substantially from those with MSRE [[pedigree]] include the ''[[Stable Salt Reactor]]''(SSR) concept promoted by MOLTEX, which encases the molten salt in hundreds of the common solid [[fuel rod]]s that are already well established in the nuclear industry. This latter British design was found to be the most competitive for [[Small modular reactor]] development by a British based consultancy firm ''Energy Process Development'' in 2015.<ref>[http://www.daretothink.org/europe-moltex-stable-salt-reactor/ Europe: Moltex’ Stable Salt Reactor]</ref><ref>[http://analysis.nuclearenergyinsider.com/moltex-energy-sees-uk-canada-smr-licensing-springboard-asia Moltex Energy sees UK, Canada SMR licensing as springboard to Asia Jun 28, 2016]</ref>

==== Supercritical-water-cooled reactor (SCWR) ====
[[File:Supercritical-Water-Cooled Reactor.svg|right|thumb|Supercritical-Water-Cooled Reactor (SCWR)]]
{{Main article|Supercritical water reactor}}
The '''supercritical water reactor''' (SCWR)<ref name="Roadmap"/> is a [[reduced moderation water reactor]] concept that, due to the average speed of the neutrons that would cause the fission events within the fuel being faster than [[thermal neutron]]s, it is more accurately termed an [[epithermal neutron|epithermal reactor]] than a thermal reactor. It uses [[supercritical fluid|supercritical water]] as the working fluid. SCWRs are basically [[light water reactor]]s (LWR) operating at higher pressure and temperatures with a direct, once-through heat exchange cycle. As most commonly envisioned, it would operate on a direct cycle, much like a boiling water reactor ([[BWR]]), but since it uses supercritical water (not to be confused with [[Critical mass (nuclear)|critical mass]]) as the working fluid, it would have only one water phase present, which makes the supercritical heat exchange method more similar to a pressurized water reactor ([[Pressurized water reactor|PWR]]). It could operate at much higher temperatures than both current PWRs and BWRs.

Supercritical water-cooled reactors (SCWRs) are promising advanced nuclear systems because of their high [[thermal efficiency]] (i.e., about 45% vs. about 33% efficiency for current LWRs) and considerable plant simplification.

The main mission of the SCWR is generation of low-cost [[electricity]]. It is built upon two proven technologies, LWRs, which are the most commonly deployed power generating reactors in the world, and superheated [[fossil fuel]] fired [[boiler]]s, a large number of which are also in use around the world. The SCWR concept is being investigated by 32 organizations in 13 countries.{{citation needed|date=October 2012}}

A SCWR Design under development is the [[VVER]]-1700/393 (VVER-SCWR or VVER-SKD) — a Russian Supercritical-water-cooled reactor with double-inlet-core and a [[breeder reactor|breeding ratio]] of 0.95.<ref name="powertecrussia.com">{{cite web |url=http://www.powertecrussia.com/blog/tag/nuclear-power/ |title=Technology Developments & Plant Efficiency for the Russian Nuclear Power Generation Market Wednesday |date=March 24, 2010}}</ref>

=== Fast reactors ===
A [[Fast-neutron reactor|fast reactor]] directly uses the fast neutrons emitted by fission, without moderation. Unlike thermal neutron reactors, fast neutron reactors can be configured to "'''burn'''", or fission, all [[actinides]], and given enough time, therefore drastically reduce the actinides fraction in [[spent nuclear fuel]] produced by the present world fleet of thermal neutron [[light water reactor]]s, thus closing the [[nuclear fuel cycle]]. Alternatively, if configured differently, they can also [[breeder reactor|'''breed''']] more actinide fuel than they consume.

==== Gas-cooled fast reactor (GFR) ====
[[File:Gas-Cooled Fast Reactor Schemata.svg|right|thumb|Gas-Cooled Fast Reactor (GFR)]]
{{Main article|Gas-cooled fast reactor}}
The '''gas-cooled fast reactor''' (GFR)<ref name="Roadmap"/> system features a fast-neutron spectrum and closed fuel cycle for efficient conversion of [[Fertile material|fertile uranium]] and management of actinides. The reactor is [[helium]]-cooled and with an outlet temperature of 850 °C it is an evolution of the [[very-high-temperature reactor]] (VHTR) to a more sustainable fuel cycle. It will use a direct [[Brayton cycle]] [[Closed-cycle gas turbine|gas turbine]] for high thermal efficiency. Several fuel forms are being considered for their potential to operate at very high temperatures and to ensure an excellent retention of [[Nuclear fission|fission]] products: composite [[ceramic]] fuel, advanced fuel particles, or ceramic clad elements of actinide compounds. Core configurations are being considered based on pin- or plate-based fuel assemblies or prismatic blocks.

The European Sustainable Nuclear Industrial Initiative is funding three Generation IV reactor systems, one of which is a gas-cooled fast reactor, called ''Allegro'', 100 MW(t), which will be built in a central or eastern European country with construction expected to begin in 2018.<ref name="euronuclear.org">{{cite web |url=https://www.euronuclear.org/1-information/news/Gen-IV.htm |title=The European Sustainable Nuclear Industrial Initiative (ESNII) will support three Generation IV reactor systems: a sodium-cooled fast reactor, or SFR, called ''Astrid'' that is proposed by France; a gas-cooled fast reactor, GFR, called ''Allegro'' supported by central and eastern Europe; and a lead-cooled fast reactor, LFR, technology pilot called ''Myrrha'' that is proposed by Belgium.}}</ref> The central European [[Visegrád Group]] are committed to pursuing the technology.<ref>{{cite web |url=http://www.alphagalileo.org/ViewItem.aspx?ItemId=133111&CultureCode=en |title=The V4G4 Centre of Excellence for performing joint research, development and innovation in the field of Generation-4 (G4) nuclear reactors have been established. 20 July 2013 National Center for Nuclear Research (NCBJ]}}</ref> In 2013 German, British, and French institutes finished a 3-year collaboration study on the follow on industrial scale design, known as ''GoFastR''.<ref>{{cite web |url=http://www.ist-world.org/ProjectDetails.aspx?ProjectId=5cb8f3f283574cc6b2bdbf72533172d8 |title=the European Gas cooled Fast Reactor.}}</ref> They were funded by the EU's 7th FWP [[framework programme]], with the goal of making a sustainable VHTR.<ref>{{cite web |url=http://www.2020-horizon.com/GOFASTR-European-Gas-Cooled-Fast-Reactor%28GOFASTR%29-s312.html |title=The GOFASTR research program}}</ref>

==== Sodium-cooled fast reactor (SFR) ====
[[File:Sodium-Cooled Fast Reactor Schemata.svg|right|thumb|Pool design Sodium-Cooled Fast Reactor (SFR)]]
{{Main article|Sodium-cooled fast reactor}}
{{see also|Prototype Fast Breeder Reactor|Experimental Breeder Reactor II|S-PRISM|BN-800 reactor|Toshiba 4S}}

In India, the [[Fast Breeder Test Reactor]] reached criticality in October 1985. In September 2002, fuel burn-up in the FBTR for the first time reached the 100,000 megawatt-days per metric ton uranium (MWd/MTU) mark. This is considered an important milestone in breeder reactor technology. Using the experience gained from the operation of the FBTR, the [[Prototype Fast Breeder Reactor]], a 500 MWe Sodium cooled fast reactor is being built at a cost of INR 5,677 crores (~US$900 million) and is expected to be critical by June 2016. The PFBR will be followed by six more Commercial Fast Breeder Reactors (CFBRs) of 600 MWe each.

The SFR<ref name="Roadmap"/> is a project that builds on two closely related existing projects, the liquid metal [[Breeder reactor#Fast breeder reactor|fast breeder reactor]] and the [[integral fast reactor]].

The goals are to increase the efficiency of uranium usage by [[breeder reactor|breeding]] plutonium and eliminating the need for [[transuranic]] isotopes ever to leave the site. The reactor design uses an unmoderated core running on [[fast neutron]]s, designed to allow any transuranic isotope to be consumed (and in some cases used as fuel). In addition to the benefits of removing the long [[half-life]] transuranics from the waste cycle, the SFR fuel expands when the reactor overheats, and the chain reaction automatically slows down. In this manner, it is passively safe.<ref>{{cite web |url=http://www.ne.anl.gov/About/hn/logos-winter02-psr.shtml|title=Passively safe reactors rely on nature to keep them cool|author=David Baurac}}</ref>

The SFR reactor concept is cooled by liquid [[sodium]] and fueled by a metallic alloy of uranium and [[plutonium]] or [[spent nuclear fuel]], the "nuclear waste" of [[light water reactor]]s. The SFR fuel is contained in steel cladding with liquid sodium filling in the space between the clad elements which make up the fuel assembly. One of the design challenges of an SFR is the risks of handling sodium, which reacts explosively if it comes into contact with water. However, the use of liquid metal instead of water as coolant allows the system to work at atmospheric pressure, reducing the risk of leakage.

The European Sustainable Nuclear Industrial Initiative is funding three Generation IV reactor systems, one of which is a sodium-cooled fast reactor, called ''[[ASTRID (reactor)|ASTRID]]'', Advanced Sodium Technical Reactor for Industrial Demonstration, [[Areva]], [[Commissariat à l'énergie atomique et aux énergies alternatives|CEA]] and [[Électricité de France|EDF]] are leading the design with British collaboration.<ref>{{cite web |url=http://www.power-eng.com/articles/2010/11/areva--cea-secure.html |title=Areva, CEA secure EUR650m funding to develop ASTRID sodium-cooled Generation IV reactor 11/11/2010}}</ref><ref>{{cite web |url=http://www.powermag.com/uk-and-france-sign-landmark-civil-nuclear-cooperation-agreement/ |title=UK and France Sign Landmark Civil Nuclear Cooperation Agreement 02/22/2012 . POWERnews}}</ref> Astrid will be rated about 600 MWe and is proposed to be built in France, near to the [[Phénix]] reactor. A final decision in construction is to be made in 2019<ref name="euronuclear.org"/>

The [[China|PRC]]'s first commercial-scale, 800 MWe, fast neutron reactor, to be situated near [[Sanming]] in [[Fujian province]] will be a SFR. In 2009 an agreement was signed that would entail the Russian [[BN-800 reactor]] design to be sold to the PRC once it is completed, this would be the first time commercial-scale fast neutron reactors have ever been exported.<ref>{{cite web |url=http://www.world-nuclear-news.org/C-Joint_venture_launched_for_Chinese_fast_reactor-3004104.html |title=Joint venture launched for Chinese fast reactor}}</ref> The BN-800 reactor became operational in 2014.

The 400 MWe [[Fast Flux Test Facility]] operated successfully for ten years at the Hanford site in Washington State.

The 20 MWe [[EBR II]] operated successfully for over thirty years at the Idaho National Laboratory, until it was shut down in 1994.

==== Lead-cooled fast reactor (LFR) ====
[[File:Lead-Cooled Fast Reactor Schemata.svg|right|thumb|Lead-Cooled Fast Reactor (LFR)]]
{{Main article|Lead-cooled fast reactor}}
{{See also|MYRRHA}}
The '''lead-cooled fast reactor'''<ref name="Roadmap">{{cite journal| year=2002 | title=A Technology Roadmap for Generation IV Nuclear Energy Systems | last=US DOE Nuclear Energy Research Advisory Committee |volume=GIF-002-00|url=http://nuclear.energy.gov/genIV/documents/gen_iv_roadmap.pdf}}</ref> features a fast-neutron-spectrum [[lead]] or [[lead]]/[[bismuth]] [[eutectic]] ([[Lead-bismuth eutectic|LBE]]) liquid-metal-cooled reactor with a closed [[Nuclear fuel cycle|fuel cycle]]. Options include a range of plant ratings, including a "battery" of 50 to 150 MW of electricity that features a very long refueling interval, a modular system rated at 300 to 400 MW, and a large monolithic plant option at 1,200 MW. (The term ''battery'' refers to the long-life, factory-fabricated core, not to any provision for electrochemical energy conversion.) The fuel is metal or nitride-based containing [[Fertile material|fertile uranium]] and [[transuranic]]s. The LFR is cooled by natural [[convection]] with a reactor outlet coolant temperature of 550 °C, possibly ranging up to 800 °C with advanced materials. The higher temperature enables the production of [[Thermochemical cycle|hydrogen by thermochemical processes]].

The European Sustainable Nuclear Industrial Initiative is funding three Generation IV reactor systems, one of which is a lead-cooled fast reactor that is also an [[Subcritical reactor|accelerator-driven sub-critical]] reactor, called ''[[MYRRHA]]'', 100 MW(t), which will be built in [[Belgium]] with construction expected to begin after 2014 and the industrial scale version, known as ''Alfred'', slated to be constructed sometime after 2017. A reduced-power model of Myrrha called ''Guinevere'' was started up at [[Mol, Belgium|Mol]] in March 2009.<ref name="euronuclear.org"/> In 2012 the research team reported that Guinevere was operational.<ref>{{cite news|last1=Hellemans|first1=Alexander|title=Reactor-Accelerator Hybrid Achieves Successful Test Run|url=http://news.sciencemag.org/physics/2012/01/reactor-accelerator-hybrid-achieves-successful-test-run|accessdate=29 December 2014|work=Science Insider|date=12 January 2012}}</ref>

Two other lead-cooled fast reactors under development are the SVBR-100, a modular 100 MWe lead-bismuth cooled fast neutron reactor concept designed by OKB [[Gidropress]] in Russia and the [[BREST (Reactor)|BREST-OD-300]] (Lead-cooled fast reactor) 300 MWe, to be developed after the SVBR-100, and built over 2016-20, it will dispense with the [[Uranium-238|fertile blanket]] around the core and will supersede the sodium cooled [[BN-600 reactor]] design, to purportedly give enhanced proliferation resistance.<ref name="powertecrussia.com"/>

{| class=wikitable
|-
! System
! Neutron Spectrum
! Coolant
! Temperature (°C)
! Fuel Cycle
! Size (MW)
!Example developers
|-
| [[Very high temperature reactor|VHTR]]
| Thermal
| Helium
| 900–1000
| Open
| 250–300
|[[Japan Atomic Energy Agency|JAEA]] ([[HTTR]]), [[Tsinghua University]] ([[HTR-10]]), X-energy<ref name="energy.gov">{{cite web|title=Energy Department Announces New Investments in Advanced Nuclear Power Reactors...|url=http://www.energy.gov/articles/energy-department-announces-new-investments-advanced-nuclear-power-reactors-help-meet|website=[[United States Department of Energy|US Department of Energy]]|accessdate=16 January 2016}}</ref>
|-
| [[Sodium-cooled fast reactor|SFR]]
| Fast
| Sodium
| 550
| Closed
| 30–150, 300–1500, 1000–2000
|[[TerraPower]] ([[Traveling wave reactor|TWR]]), Toshiba ([[Toshiba 4S|4S]]), [[GE Hitachi Nuclear Energy]] ([[PRISM (reactor)|PRISM]])
|-
| [[Supercritical water reactor|SCWR]]
| Thermal/fast
| Water
| 510–625
| Open/closed
| 300–700, 1000–1500
|
|-
| [[Gas-cooled fast reactor|GFR]]
| Fast
| Helium
| 850
| Closed
| 1200
|[[Energy Multiplier Module]]
|-
| [[Lead-cooled fast reactor|LFR]]
| Fast
| Lead
| 480–800
| Closed
| 20–180, 300–1200, 600–1000
|
|-
| [[Molten salt reactor|MSR]]
| Fast/thermal
| Fluoride/Chloride salts
| 700–800
| Closed
| 250, 1000
|[[Flibe Energy]] ([[Liquid fluoride thorium reactor|LFTR]]), [[Transatomic Power]], Thorium Tech Solution ([[Fuji Molten Salt Reactor|FUJI MSR]]), Terrestrial Energy ([[IMSR]]), [[Southern Company Services|Southern Company]]<ref name="energy.gov"/>
|}
<ref>https://www.gen-4.org/gif/upload/docs/application/pdf/2013-09/gif_rd_outlook_for_generation_iv_nuclear_energy_systems.pdf</ref>

== Advantages and disadvantages ==
Relative to current nuclear power plant technology, the claimed benefits for 4th generation reactors include:
* Nuclear waste that remains radioactive for a few centuries instead of millennia<ref>{{cite web |title=Strategies to Address Global Warming |url=http://www.columbia.edu/~jeh1/mailings/2009/20090713_Strategies.pdf}}</ref>
* 100-300 times more energy yield from the same amount of nuclear fuel<ref>{{cite web |title=4th Generation Nuclear Power |url=http://www.ossfoundation.us/projects/energy/nuclear}}</ref>
* Broader range of fuels, and even unencapsulated raw fuels (non-pebble [[Molten Salt Reactor|MSR]], [[LFTR]]).
* In some reactors, the ability to consume existing nuclear waste in the production of electricity, that is, a Closed [[nuclear fuel cycle]]. This strengthens the argument to deem [[nuclear power as renewable energy]].
* Improved operating safety features, such as (depending on design) avoidance of pressurized operation, automatic passive (unpowered, uncommanded) reactor shutdown, avoidance of water cooling and the associated risks of loss of water (leaks or boiling) and hydrogen generation/explosion and contamination of coolant water.

Nuclear reactors do not emit CO2 during operation, although like all [[low carbon power]] sources, the mining and construction phase can result in CO2 emissions, if energy sources which are not carbon neutral (such as fossil fuels), or CO2 emitting cements are used during the construction process.
A 2012 [[Yale University]] review published in the Journal of Industrial Ecology analyzing {{CO2}} [[life cycle assessment]] (LCA) emissions from [[nuclear power]] determined that:<ref name="Warner + Heath, JoIE">Warner, Ethan S.; Heath, Garvin A. [http://onlinelibrary.wiley.com/doi/10.1111/j.1530-9290.2012.00472.x/full Life Cycle Greenhouse Gas Emissions of Nuclear Electricity Generation: Systematic Review and Harmonization], ''Journal of Industrial Ecology'', [[Yale University]], published online April 17, 2012, doi: 10.1111/j.1530-9290.2012.00472.x.</ref>
{{Quote|''"The collective LCA literature indicates that life cycle [[Greenhouse gas|GHG]] [ greenhouse gas ] emissions from nuclear power are only a fraction of traditional fossil sources and comparable to renewable technologies."''}}
Although the paper primarily dealt with data from [[Generation II reactor]]s, and did not analyze the {{CO2}} emissions by 2050 of the presently under construction [[Generation III reactor]]s, it did summarize the Life Cycle Assessment findings of in development reactor technologies.''{{Quote|FBRs ''[ [[Fast Breeder Reactor]]s ]'' have been evaluated in the LCA literature. The limited literature that evaluates this potential future technology reports [[median]] life cycle GHG emissions... similar to or lower than LWRs[ Gen II [[light water reactor]]s ] and purports to consume little or no [[uranium market|uranium ore]].}}

A specific risk of the sodium-cooled fast reactor is related to using metallic sodium as a coolant. In case of a breach, sodium explosively reacts with water. Fixing breaches may also prove dangerous, as the cheapest noble gas [[argon]] is also used to prevent sodium oxidation. Argon, like helium, can displace oxygen in the air and can pose [[hypoxia (environmental)|hypoxia]] concerns, so workers may be exposed to this additional risk. This is a pertinent problem as can be testified by the events at the [[LMFBR|loop type]] [[Monju Nuclear Power Plant|Prototype Fast Breeder Reactor Monju]] at Tsuruga, Japan.<ref>{{cite news |title=Japan Strains to Fix a Reactor Damaged Before Quake |url=http://www.nytimes.com/2011/06/18/world/asia/18japan.html | work=The New York Times | first=Hiroko |last=Tabuchi |date=17 June 2011}}</ref>
Using lead or molten salts mitigates this problem by making the coolant less reactive and allowing a high freezing temperature and low pressure in case of a leak. Disadvantages of lead compared to sodium are much higher viscosity, much higher density, lower heat capacity, and more radioactive neutron activation products.

In many cases, there is already a large amount of experience built up with numerous proof of concept Gen IV designs. For example, the reactors at [[Fort St. Vrain Generating Station]] and [[HTR-10]] are similar to the proposed Gen IV [[VHTR]] designs, and the [[LMFBR|pool type]] [[EBR-II]], [[Phénix]] and [[BN-600]] reactor are similar to the proposed pool type Gen IV Sodium Cooled Fast reactors being designed.

== See also ==
{{colbegin|3}}
* [[Nuclear reactor]]
* [[Nuclear material]]
* [[Nuclear physics]]
* [[List of reactor types#Reactor types|List of reactor types]]
* [[Generation II reactor]]
* [[Generation III reactor]]
* [[Integral Fast Reactor]]
* [[Liquid fluoride thorium reactor]]
* [[Breeder reactor]]
* [[Small modular reactor]]
{{colend}}

==References==
{{Reflist|30em}}

== External links ==
* [https://inlportal.inl.gov/portal/server.pt?open=514&objID=1361&parentname=CommunityPage&parentid=10&mode=2&in_hi_userid=200&cached=true Article from Idaho National Laboratory detailing some current efforts at developing Gen. IV reactors.]
* [http://www.gen-4.org/ Generation IV International Forum (GIF)]
* [http://nuclear.energy.gov/genIV/neGenIV1.html U.S. Department of Energy Office of Nuclear Energy, Science and Technology]
* [http://www.engr.utk.edu/nuclear/colloquia/slides/Gen%20IV%20U-Tenn%20Presentation.pdf Gen IV presentation]
* [http://www.ecology.at/ecology/files/pr577_1.pdf Science or Fiction - Is there a Future for Nuclear?] (Nov. 2007) - A publication from the Austrian [[Ecology Institute (Austria)|Ecology Institute]] about 'Generation IV' and Fusion reactors.
* {{cite web |url=http://memagazine.asme.org/Articles/2011/December/Nuclear_Power_After_Fukushima.cfm |title=Nuclear Power After Fukushima |author=Gail H. Marcus |date=December 2011 |work=Mechanical Engineering (the magazine of [[ASME]]) |accessdate=23 January 2012}} "In the wake of a severe plant accident, advanced reactor designs are getting renewed attention."
* [http://www.itheo.org/ International Thorium Energy Organisation - www.IThEO.org]
* [http://www.ithec.org/ International Thorium Energy Committee - iThEC]

{{Nuclear fission reactors}}

[[Category:Nuclear power reactor types]]
[[Category:Idaho National Laboratory]]

Benutzer:Snackroeg/Kernreaktoren der Generation 5

2016-11-13T03:05:39Z

Boundarylayer: /* Molten-salt reactor (MSR) */ Stable Salt Reactor page link added

[[File:GenIVRoadmap-en.svg|thumb|480px|Nuclear Energy Systems Deployable no later than 2030 and offering significant advances in sustainability, safety and reliability, and economics]]

'''Generation IV reactors''' ('''Gen IV''') are a set of [[nuclear reactor]] designs currently being researched for commercial applications by the Generation IV International Forum, with [[Technology readiness level]]s varying between the level requiring a demonstration, to economical competitive implementation. They are motivated by a variety of goals including improved safety, sustainability, efficiency, and cost.

Most of these designs are generally not expected to be available for commercial construction before 2030–40.<ref name="Generation IV">[http://www.world-nuclear.org/info/Nuclear-Fuel-Cycle/Power-Reactors/Generation-IV-Nuclear-Reactors/]</ref> Presently the majority of reactors in operation around the world are considered [[Generation II reactor|second generation reactor]] systems, as the vast majority of the [[Generation I reactor|first-generation]] systems were retired some time ago, and there are only a dozen or so [[Generation III reactor]]s in operation (2014). [[Nuclear reactor#Generation V+ reactors|Generation V reactors]] refer to reactors that are purely theoretical and are therefore not yet considered feasible in the short term, resulting in limited [[R&D]] funding.

== History ==
The Generation IV International Forum (GIF) is "a co-operative international endeavour which was set up to carry out the research and development needed to establish the feasibility and performance capabilities of the next generation nuclear energy systems."<ref>{{Cite web|url=https://www.gen-4.org/gif/jcms/c_9260/public|title=GIF Portal - Home - Public|website=www.gen-4.org|access-date=2016-07-25}}</ref> It was founded in 2001. There are currently ten active members of the Generation IV International Forum (GIF): [[Canada]], [[China]], the [[European Atomic Energy Community]] (Euratom), [[France]], [[Japan]], [[Russia]], [[South Africa]], [[South Korea]], [[Switzerland]], and the [[United States]]. The non-active members are [[Argentina]], [[Brazil]], and the [[United Kingdom]].<ref name="gen-4">{{cite web|url=https://www.gen-4.org/gif/jcms/c_9492/members|title=GIF Membership|website=gen-4.org|accessdate=28 October 2014}}</ref> Switzerland joined in 2002, Euratom in 2003, and China and Russia in 2006. The remaining countries (excluding Australia) were founding members.<ref name="gen-4" />

The 36th GIF meeting in [[Brussels]] was held in November 2013.<ref>{{cite web|url=http://www.energy.gov/ne/articles/generation-iv-international-forum-updates-technology-roadmap-and-builds-future|title=generation IV international forum updates technology roadmap and builds future. DOE}}</ref><ref>{{cite web|url=http://events.r20.constantcontact.com/register/event?llr=mscrkjkab&oeidk=a07e7melf609716b2c6|title=The Generation IV international forum holds their 36th meeting on Monday 18th Nov 2013 in Brussels.}}</ref> The ''Technology Roadmap Update for Generation IV Nuclear Energy Systems'' was published in January 2014 which details R&D objectives for the next decade.<ref>[https://web.archive.org/web/20140625102915/https://www.gen-4.org/gif/upload/docs/application/pdf/2014-03/gif-tru2014.pdf Technology Roadmap Update for Generation IV Nuclear Energy Systems]</ref> A breakdown of the reactor designs being researched by each forum member has been made available.<ref>[https://web.archive.org/web/20140708023538/https://www.gen-4.org/gif/upload/docs/application/pdf/2014-03/gif_overview_presentation_v9_final3_web.pdf Generation IV International Forum, overview, John E. Kelly, page 15]</ref>

[[Nuclear power in Australia|Australia]] joined the forum in 2016.<ref>http://archive.is/22e5F</ref>

== Reactor types ==
Many reactor types were considered initially; however, the list was downsized to focus on the most promising technologies and those that could most likely meet the goals of the Gen IV initiative.<ref name="Generation IV"/> Three systems are nominally [[thermal reactor]]s and three are [[fast reactor]]s. The Very High Temperature Reactor (VHTR) is also being researched for potentially providing high quality process heat for [[thermochemical cycle|hydrogen production]]. The fast reactors offer the possibility of burning [[actinides]] to further reduce waste and of being able to "[[breeder reactor|breed more fuel]]" than they consume. These systems offer significant advances in sustainability, safety and reliability, economics, proliferation resistance (depending on perspective) and physical protection.

{| class=wikitable
|-
! System
! Neutron Spectrum
! Coolant
! Temperature (°C)
! Fuel Cycle
! Size (MW)
!Example developers
|-
| [[Very high temperature reactor|VHTR]]
| Thermal
| Helium
| 900–1000
| Open
| 250–300
|[[Japan Atomic Energy Agency|JAEA]] ([[HTTR]]), [[Tsinghua University]] ([[HTR-10]]), X-energy<ref name="energy.gov">{{cite web|title=Energy Department Announces New Investments in Advanced Nuclear Power Reactors...|url=http://www.energy.gov/articles/energy-department-announces-new-investments-advanced-nuclear-power-reactors-help-meet|website=[[United States Department of Energy|US Department of Energy]]|accessdate=16 January 2016}}</ref>
|-
| [[Sodium-cooled fast reactor|SFR]]
| Fast
| Sodium
| 550
| Closed
| 30–150, 300–1500, 1000–2000
|[[TerraPower]] ([[Traveling wave reactor|TWR]]), Toshiba ([[Toshiba 4S|4S]]), [[GE Hitachi Nuclear Energy]] ([[PRISM (reactor)|PRISM]])
|-
| [[Supercritical water reactor|SCWR]]
| Thermal/fast
| Water
| 510–625
| Open/closed
| 300–700, 1000–1500
|
|-
| [[Gas-cooled fast reactor|GFR]]
| Fast
| Helium
| 850
| Closed
| 1200
|[[Energy Multiplier Module]]
|-
| [[Lead-cooled fast reactor|LFR]]
| Fast
| Lead
| 480–800
| Closed
| 20–180, 300–1200, 600–1000
|
|-
| [[Molten salt reactor|MSR]]
| Fast/thermal
| Fluoride/Chloride salts
| 700–800
| Closed
| 250, 1000
|[[Flibe Energy]] ([[Liquid fluoride thorium reactor|LFTR]]), [[Transatomic Power]], Thorium Tech Solution ([[Fuji Molten Salt Reactor|FUJI MSR]]), Terrestrial Energy ([[IMSR]]), [[Southern Company Services|Southern Company]]<ref name="energy.gov"/>
|}
<ref>https://www.gen-4.org/gif/upload/docs/application/pdf/2013-09/gif_rd_outlook_for_generation_iv_nuclear_energy_systems.pdf</ref>

=== Thermal reactors ===
A [[Thermal-neutron reactor|thermal reactor]] is a [[nuclear reactor]] that uses slow or [[thermal neutrons]]. A [[neutron moderator]] is used to slow the [[neutron]]s emitted by fission to make them more likely to be captured by the fuel.

==== Very-high-temperature reactor (VHTR) ====
[[File:Very High Temperature Reactor.svg|right|thumb|Very-High-Temperature Reactor (VHTR)]]
{{Main article|Very high temperature reactor}}
{{see also|Fort St. Vrain Generating Station|HTTR|HTR-10}}
The '''very high temperature reactor''' concept uses a [[graphite]]-moderated core with a once-through [[uranium]] fuel cycle, using helium or molten salt as the [[Very high temperature reactor#Coolant|coolant]]. This reactor design envisions an outlet temperature of 1,000 °C. The reactor core can be either a prismatic-block or a [[pebble bed reactor]] design. The high temperatures enable applications such as process heat or [[hydrogen]] production via the thermochemical [[Sulfur-iodine cycle|iodine-sulfur]] process. It would also be [[Passive nuclear safety|passively safe]].

The planned construction of the first VHTR, the South African PBMR ([[pebble bed modular reactor]]), lost government funding in February, 2010.<ref>[http://www.powergenworldwide.com/index/display/articledisplay/6322207443/articles/power-engineering-international/volume-18/Issue_3/regulars/world-news/INTERNATIONAL.html South Africa to stop funding Pebble Bed nuclear reactor]</ref> A pronounced increase of costs and concerns about possible unexpected technical problems had discouraged potential investors and customers.

The [[Peoples Republic of China]] began construction of a 200-MW High Temperature Pebble bed reactor in 2012 as a successor to its [[HTR-10]].<ref>[http://www.nucnet.org/all-the-news/2013/01/07/china-begins-construction-of-first-generation-iv-htr-pm-unit Nucnet Report: 'China Begins Construction of First Generation IV HTR-PM Unit', 7 January 2013]</ref>

Also in 2012, as part of the [[Next Generation Nuclear Plant]] competition, [[Idaho National Laboratory]] approved a design similar to [[Areva]]'s prismatic block [http://us.areva.com/EN/home-3225/areva-inc-areva-htgr.html Antares reactor] as the chosen [[HTGR]] to be deployed as a prototype by 2021. It was in competition with [[General Atomics]]' [[Gas turbine modular helium reactor]] and [[Westinghouse Electric Company|Westinghouse]]'s [[Pebble Bed Modular Reactor]].<ref name="World nuclear news">{{cite web|url=http://www.world-nuclear-news.org/NN-Areva_modular_reactor_selected_for_NGNP_development-1502124.html|title=INL approves Antares design}}</ref>

==== Molten-salt reactor (MSR) ====
[[File:Molten Salt Reactor.svg|right|thumb|Molten Salt Reactor (MSR)]]
{{Main article|Molten salt reactor}}
{{see also|Liquid fluoride thorium reactor}}
A '''molten salt reactor'''<ref name="Roadmap"/> is a type of [[nuclear reactor]] where the primary [[coolant]], or even the fuel itself is a molten salt mixture. There have been many designs put forward for this type of reactor and a few prototypes built. The early concepts and many current ones rely on [[nuclear fuel]] dissolved in the molten [[fluoride]] salt as [[uranium tetrafluoride]] (UF4) or [[thorium tetrafluoride]] (ThF4). The fluid would reach [[Nuclear reactor physics#Criticality|criticality]] by flowing into a [[graphite]] core which would also serve as the [[neutron moderator|moderator]]. Many current concepts rely on fuel that is dispersed in a graphite matrix with the molten salt providing low pressure, high temperature cooling.

The Gen IV MSR is more accurately termed an [[epithermal neutron|epithermal reactor]] than a thermal reactor due to the average speed of the neutrons that would cause the fission events within its fuel being faster than [[thermal neutron]]s.<ref>{{cite web |url=https://inlportal.inl.gov/portal/server.pt?open=514&objID=1361&parentname=CommunityPage&parentid=10&mode=2&in_hi_userid=200&cached=true |title=Idaho National Laboratory detailing some current efforts at developing Gen. IV reactors}}</ref>

The principle of a MSR can be used for thermal, epithermal and fast reactors. Since 2005 the focus has moved towards a fast spectrum MSR (MSFR).<ref>H. Boussier, S. Delpech, V. Ghetta et Al. : The Molten Salt Reactor (MSR) in Generation IV: Overview and Perspectives, GIF SYMPOSIUM PROCEEDINGS/2012 ANNUAL REPORT, NEA No. 7141, pp95 [https://www.gen-4.org/gif/jcms/c_44720/annual-reports]
</ref>

While most MSR designs being pursued are largely derived from the 1960s [[Molten-Salt Reactor Experiment]](MSRE), variants of molten salt technology include the conceptual ''[[Dual fluid reactor]]'' which is being designed with lead as a cooling medium but molten salt fuel, commonly as the metal chloride e.g [[Plutonium(III) chloride]], to aid in greater "nuclear waste" closed-fuel cycle capabilities.
Other notable approaches differing substantially from those with MSRE [[pedigree]] include the ''[[Stable Salt Reactor]]''(SSR) concept promoted by MOLTEX, which encases the molten salt in hundreds of the common solid [[fuel rod]]s that are already well established in the nuclear industry. This latter British design was found to be the most competitive for [[Small modular reactor]] development by a British based consultancy firm ''Energy Process Development'' in 2015.<ref>[http://www.daretothink.org/europe-moltex-stable-salt-reactor/ Europe: Moltex’ Stable Salt Reactor]</ref><ref>[http://analysis.nuclearenergyinsider.com/moltex-energy-sees-uk-canada-smr-licensing-springboard-asia Moltex Energy sees UK, Canada SMR licensing as springboard to Asia Jun 28, 2016]</ref>

==== Supercritical-water-cooled reactor (SCWR) ====
[[File:Supercritical-Water-Cooled Reactor.svg|right|thumb|Supercritical-Water-Cooled Reactor (SCWR)]]
{{Main article|Supercritical water reactor}}
The '''supercritical water reactor''' (SCWR)<ref name="Roadmap"/> is a [[reduced moderation water reactor]] concept that, due to the average speed of the neutrons that would cause the fission events within the fuel being faster than [[thermal neutron]]s, it is more accurately termed an [[epithermal neutron|epithermal reactor]] than a thermal reactor. It uses [[supercritical fluid|supercritical water]] as the working fluid. SCWRs are basically [[light water reactor]]s (LWR) operating at higher pressure and temperatures with a direct, once-through heat exchange cycle. As most commonly envisioned, it would operate on a direct cycle, much like a boiling water reactor ([[BWR]]), but since it uses supercritical water (not to be confused with [[Critical mass (nuclear)|critical mass]]) as the working fluid, it would have only one water phase present, which makes the supercritical heat exchange method more similar to a pressurized water reactor ([[Pressurized water reactor|PWR]]). It could operate at much higher temperatures than both current PWRs and BWRs.

Supercritical water-cooled reactors (SCWRs) are promising advanced nuclear systems because of their high [[thermal efficiency]] (i.e., about 45% vs. about 33% efficiency for current LWRs) and considerable plant simplification.

The main mission of the SCWR is generation of low-cost [[electricity]]. It is built upon two proven technologies, LWRs, which are the most commonly deployed power generating reactors in the world, and superheated [[fossil fuel]] fired [[boiler]]s, a large number of which are also in use around the world. The SCWR concept is being investigated by 32 organizations in 13 countries.{{citation needed|date=October 2012}}

A SCWR Design under development is the [[VVER]]-1700/393 (VVER-SCWR or VVER-SKD) — a Russian Supercritical-water-cooled reactor with double-inlet-core and a [[breeder reactor|breeding ratio]] of 0.95.<ref name="powertecrussia.com">{{cite web |url=http://www.powertecrussia.com/blog/tag/nuclear-power/ |title=Technology Developments & Plant Efficiency for the Russian Nuclear Power Generation Market Wednesday |date=March 24, 2010}}</ref>

=== Fast reactors ===
A [[Fast-neutron reactor|fast reactor]] directly uses the fast neutrons emitted by fission, without moderation. Unlike thermal neutron reactors, fast neutron reactors can be configured to "'''burn'''", or fission, all [[actinides]], and given enough time, therefore drastically reduce the actinides fraction in [[spent nuclear fuel]] produced by the present world fleet of thermal neutron [[light water reactor]]s, thus closing the [[nuclear fuel cycle]]. Alternatively, if configured differently, they can also [[breeder reactor|'''breed''']] more actinide fuel than they consume.

==== Gas-cooled fast reactor (GFR) ====
[[File:Gas-Cooled Fast Reactor Schemata.svg|right|thumb|Gas-Cooled Fast Reactor (GFR)]]
{{Main article|Gas-cooled fast reactor}}
The '''gas-cooled fast reactor''' (GFR)<ref name="Roadmap"/> system features a fast-neutron spectrum and closed fuel cycle for efficient conversion of [[Fertile material|fertile uranium]] and management of actinides. The reactor is [[helium]]-cooled and with an outlet temperature of 850 °C it is an evolution of the [[very-high-temperature reactor]] (VHTR) to a more sustainable fuel cycle. It will use a direct [[Brayton cycle]] [[Closed-cycle gas turbine|gas turbine]] for high thermal efficiency. Several fuel forms are being considered for their potential to operate at very high temperatures and to ensure an excellent retention of [[Nuclear fission|fission]] products: composite [[ceramic]] fuel, advanced fuel particles, or ceramic clad elements of actinide compounds. Core configurations are being considered based on pin- or plate-based fuel assemblies or prismatic blocks.

The European Sustainable Nuclear Industrial Initiative is funding three Generation IV reactor systems, one of which is a gas-cooled fast reactor, called ''Allegro'', 100 MW(t), which will be built in a central or eastern European country with construction expected to begin in 2018.<ref name="euronuclear.org">{{cite web |url=https://www.euronuclear.org/1-information/news/Gen-IV.htm |title=The European Sustainable Nuclear Industrial Initiative (ESNII) will support three Generation IV reactor systems: a sodium-cooled fast reactor, or SFR, called ''Astrid'' that is proposed by France; a gas-cooled fast reactor, GFR, called ''Allegro'' supported by central and eastern Europe; and a lead-cooled fast reactor, LFR, technology pilot called ''Myrrha'' that is proposed by Belgium.}}</ref> The central European [[Visegrád Group]] are committed to pursuing the technology.<ref>{{cite web |url=http://www.alphagalileo.org/ViewItem.aspx?ItemId=133111&CultureCode=en |title=The V4G4 Centre of Excellence for performing joint research, development and innovation in the field of Generation-4 (G4) nuclear reactors have been established. 20 July 2013 National Center for Nuclear Research (NCBJ]}}</ref> In 2013 German, British, and French institutes finished a 3-year collaboration study on the follow on industrial scale design, known as ''GoFastR''.<ref>{{cite web |url=http://www.ist-world.org/ProjectDetails.aspx?ProjectId=5cb8f3f283574cc6b2bdbf72533172d8 |title=the European Gas cooled Fast Reactor.}}</ref> They were funded by the EU's 7th FWP [[framework programme]], with the goal of making a sustainable VHTR.<ref>{{cite web |url=http://www.2020-horizon.com/GOFASTR-European-Gas-Cooled-Fast-Reactor%28GOFASTR%29-s312.html |title=The GOFASTR research program}}</ref>

==== Sodium-cooled fast reactor (SFR) ====
[[File:Sodium-Cooled Fast Reactor Schemata.svg|right|thumb|Pool design Sodium-Cooled Fast Reactor (SFR)]]
{{Main article|Sodium-cooled fast reactor}}
{{see also|Experimental Breeder Reactor II|S-PRISM|BN-800 reactor|Toshiba 4S}}
The SFR<ref name="Roadmap"/> is a project that builds on two closely related existing projects, the liquid metal [[Breeder reactor#Fast breeder reactor|fast breeder reactor]] and the [[integral fast reactor]].

The goals are to increase the efficiency of uranium usage by [[breeder reactor|breeding]] plutonium and eliminating the need for [[transuranic]] isotopes ever to leave the site. The reactor design uses an unmoderated core running on [[fast neutron]]s, designed to allow any transuranic isotope to be consumed (and in some cases used as fuel). In addition to the benefits of removing the long [[half-life]] transuranics from the waste cycle, the SFR fuel expands when the reactor overheats, and the chain reaction automatically slows down. In this manner, it is passively safe.<ref>{{cite web |url=http://www.ne.anl.gov/About/hn/logos-winter02-psr.shtml|title=Passively safe reactors rely on nature to keep them cool|author=David Baurac}}</ref>

The SFR reactor concept is cooled by liquid [[sodium]] and fueled by a metallic alloy of uranium and [[plutonium]] or [[spent nuclear fuel]], the "nuclear waste" of [[light water reactor]]s. The SFR fuel is contained in steel cladding with liquid sodium filling in the space between the clad elements which make up the fuel assembly. One of the design challenges of an SFR is the risks of handling sodium, which reacts explosively if it comes into contact with water. However, the use of liquid metal instead of water as coolant allows the system to work at atmospheric pressure, reducing the risk of leakage.

The European Sustainable Nuclear Industrial Initiative is funding three Generation IV reactor systems, one of which is a sodium-cooled fast reactor, called ''[[ASTRID (reactor)|ASTRID]]'', Advanced Sodium Technical Reactor for Industrial Demonstration, [[Areva]], [[Commissariat à l'énergie atomique et aux énergies alternatives|CEA]] and [[Électricité de France|EDF]] are leading the design with British collaboration.<ref>{{cite web |url=http://www.power-eng.com/articles/2010/11/areva--cea-secure.html |title=Areva, CEA secure EUR650m funding to develop ASTRID sodium-cooled Generation IV reactor 11/11/2010}}</ref><ref>{{cite web |url=http://www.powermag.com/uk-and-france-sign-landmark-civil-nuclear-cooperation-agreement/ |title=UK and France Sign Landmark Civil Nuclear Cooperation Agreement 02/22/2012 . POWERnews}}</ref> Astrid will be rated about 600 MWe and is proposed to be built in France, near to the [[Phénix]] reactor. A final decision in construction is to be made in 2019<ref name="euronuclear.org"/>

The [[China|PRC]]'s first commercial-scale, 800 MWe, fast neutron reactor, to be situated near [[Sanming]] in [[Fujian province]] will be a SFR. In 2009 an agreement was signed that would entail the Russian [[BN-800 reactor]] design to be sold to the PRC once it is completed, this would be the first time commercial-scale fast neutron reactors have ever been exported.<ref>{{cite web |url=http://www.world-nuclear-news.org/C-Joint_venture_launched_for_Chinese_fast_reactor-3004104.html |title=Joint venture launched for Chinese fast reactor}}</ref> The BN-800 reactor became operational in 2014.

In India, the [[Prototype Fast Breeder Reactor]], a 500 MWe Sodium cooled fast reactor is being built at a cost of INR 5,677 crores (~US$900 million) and is expected to be commissioned by September 2016. The PFBR will be followed by six more Commercial Fast Breeder Reactors (CFBRs) of 500 MWe each.

The 400 MWe [[Fast Flux Test Facility]] operated successfully for ten years at the Hanford site in Washington State.

The 20 MWe [[EBR II]] operated successfully for over thirty years at the Idaho National Laboratory, until it was shut down in 1994.

==== Lead-cooled fast reactor (LFR) ====
[[File:Lead-Cooled Fast Reactor Schemata.svg|right|thumb|Lead-Cooled Fast Reactor (LFR)]]
{{Main article|Lead-cooled fast reactor}}
{{See also|MYRRHA}}
The '''lead-cooled fast reactor'''<ref name="Roadmap">{{cite journal| year=2002 | title=A Technology Roadmap for Generation IV Nuclear Energy Systems | last=US DOE Nuclear Energy Research Advisory Committee |volume=GIF-002-00|url=http://nuclear.energy.gov/genIV/documents/gen_iv_roadmap.pdf}}</ref> features a fast-neutron-spectrum [[lead]] or [[lead]]/[[bismuth]] [[eutectic]] ([[Lead-bismuth eutectic|LBE]]) liquid-metal-cooled reactor with a closed [[Nuclear fuel cycle|fuel cycle]]. Options include a range of plant ratings, including a "battery" of 50 to 150 MW of electricity that features a very long refueling interval, a modular system rated at 300 to 400 MW, and a large monolithic plant option at 1,200 MW. (The term ''battery'' refers to the long-life, factory-fabricated core, not to any provision for electrochemical energy conversion.) The fuel is metal or nitride-based containing [[Fertile material|fertile uranium]] and [[transuranic]]s. The LFR is cooled by natural [[convection]] with a reactor outlet coolant temperature of 550 °C, possibly ranging up to 800 °C with advanced materials. The higher temperature enables the production of [[Thermochemical cycle|hydrogen by thermochemical processes]].

The European Sustainable Nuclear Industrial Initiative is funding three Generation IV reactor systems, one of which is a lead-cooled fast reactor that is also an [[Subcritical reactor|accelerator-driven sub-critical]] reactor, called ''[[MYRRHA]]'', 100 MW(t), which will be built in [[Belgium]] with construction expected to begin after 2014 and the industrial scale version, known as ''Alfred'', slated to be constructed sometime after 2017. A reduced-power model of Myrrha called ''Guinevere'' was started up at [[Mol, Belgium|Mol]] in March 2009.<ref name="euronuclear.org"/> In 2012 the research team reported that Guinevere was operational.<ref>{{cite news|last1=Hellemans|first1=Alexander|title=Reactor-Accelerator Hybrid Achieves Successful Test Run|url=http://news.sciencemag.org/physics/2012/01/reactor-accelerator-hybrid-achieves-successful-test-run|accessdate=29 December 2014|work=Science Insider|date=12 January 2012}}</ref>

Two other lead-cooled fast reactors under development are the SVBR-100, a modular 100 MWe lead-bismuth cooled fast neutron reactor concept designed by OKB [[Gidropress]] in Russia and the [[BREST (Reactor)|BREST-OD-300]] (Lead-cooled fast reactor) 300 MWe, to be developed after the SVBR-100, and built over 2016-20, it will dispense with the [[Uranium-238|fertile blanket]] around the core and will supersede the sodium cooled [[BN-600 reactor]] design, to purportedly give enhanced proliferation resistance.<ref name="powertecrussia.com"/>

== Advantages and disadvantages ==
Relative to current nuclear power plant technology, the claimed benefits for 4th generation reactors include:
* Nuclear waste that remains radioactive for a few centuries instead of millennia<ref>{{cite web |title=Strategies to Address Global Warming |url=http://www.columbia.edu/~jeh1/mailings/2009/20090713_Strategies.pdf}}</ref>
* 100-300 times more energy yield from the same amount of nuclear fuel<ref>{{cite web |title=4th Generation Nuclear Power |url=http://www.ossfoundation.us/projects/energy/nuclear}}</ref>
* Broader range of fuels, and even unencapsulated raw fuels (non-pebble [[Molten Salt Reactor|MSR]], [[LFTR]]).
* In some reactors, the ability to consume existing nuclear waste in the production of electricity, that is, a Closed [[nuclear fuel cycle]]. This strengthens the argument to deem [[nuclear power as renewable energy]].
* Improved operating safety features, such as (depending on design) avoidance of pressurized operation, automatic passive (unpowered, uncommanded) reactor shutdown, avoidance of water cooling and the associated risks of loss of water (leaks or boiling) and hydrogen generation/explosion and contamination of coolant water.

Nuclear reactors do not emit CO2 during operation, although like all [[low carbon power]] sources, the mining and construction phase can result in CO2 emissions, if energy sources which are not carbon neutral (such as fossil fuels), or CO2 emitting cements are used during the construction process.
A 2012 [[Yale University]] review published in the Journal of Industrial Ecology analyzing {{CO2}} [[life cycle assessment]] (LCA) emissions from [[nuclear power]] determined that:<ref name="Warner + Heath, JoIE">Warner, Ethan S.; Heath, Garvin A. [http://onlinelibrary.wiley.com/doi/10.1111/j.1530-9290.2012.00472.x/full Life Cycle Greenhouse Gas Emissions of Nuclear Electricity Generation: Systematic Review and Harmonization], ''Journal of Industrial Ecology'', [[Yale University]], published online April 17, 2012, doi: 10.1111/j.1530-9290.2012.00472.x.</ref>
{{Quote|''"The collective LCA literature indicates that life cycle [[Greenhouse gas|GHG]] [ greenhouse gas ] emissions from nuclear power are only a fraction of traditional fossil sources and comparable to renewable technologies."''}}
Although the paper primarily dealt with data from [[Generation II reactor]]s, and did not analyze the {{CO2}} emissions by 2050 of the presently under construction [[Generation III reactor]]s, it did summarize the Life Cycle Assessment findings of in development reactor technologies.''{{Quote|FBRs ''[ [[Fast Breeder Reactor]]s ]'' have been evaluated in the LCA literature. The limited literature that evaluates this potential future technology reports [[median]] life cycle GHG emissions... similar to or lower than LWRs[ Gen II [[light water reactor]]s ] and purports to consume little or no [[uranium market|uranium ore]].}}

A specific risk of the sodium-cooled fast reactor is related to using metallic sodium as a coolant. In case of a breach, sodium explosively reacts with water. Fixing breaches may also prove dangerous, as the cheapest noble gas [[argon]] is also used to prevent sodium oxidation. Argon, like helium, can displace oxygen in the air and can pose [[hypoxia (environmental)|hypoxia]] concerns, so workers may be exposed to this additional risk. This is a pertinent problem as can be testified by the events at the [[LMFBR|loop type]] [[Monju Nuclear Power Plant|Prototype Fast Breeder Reactor Monju]] at Tsuruga, Japan.<ref>{{cite news |title=Japan Strains to Fix a Reactor Damaged Before Quake |url=http://www.nytimes.com/2011/06/18/world/asia/18japan.html | work=The New York Times | first=Hiroko |last=Tabuchi |date=17 June 2011}}</ref>
Using lead or molten salts mitigates this problem by making the coolant less reactive and allowing a high freezing temperature and low pressure in case of a leak. Disadvantages of lead compared to sodium are much higher viscosity, much higher density, lower heat capacity, and more radioactive neutron activation products.

In many cases, there is already a large amount of experience built up with numerous proof of concept Gen IV designs. For example, the reactors at [[Fort St. Vrain Generating Station]] and [[HTR-10]] are similar to the proposed Gen IV [[VHTR]] designs, and the [[LMFBR|pool type]] [[EBR-II]], [[Phénix]] and [[BN-600]] reactor are similar to the proposed pool type Gen IV Sodium Cooled Fast reactors being designed.

== See also ==
{{colbegin|3}}
* [[Nuclear reactor]]
* [[Nuclear material]]
* [[Nuclear physics]]
* [[List of reactor types#Reactor types|List of reactor types]]
* [[Generation II reactor]]
* [[Generation III reactor]]
* [[Integral Fast Reactor]]
* [[Liquid fluoride thorium reactor]]
* [[Breeder reactor]]
* [[Small modular reactor]]
{{colend}}

==References==
{{Reflist|30em}}

== External links ==
* [https://inlportal.inl.gov/portal/server.pt?open=514&objID=1361&parentname=CommunityPage&parentid=10&mode=2&in_hi_userid=200&cached=true Article from Idaho National Laboratory detailing some current efforts at developing Gen. IV reactors.]
* [http://www.gen-4.org/ Generation IV International Forum (GIF)]
* [http://nuclear.energy.gov/genIV/neGenIV1.html U.S. Department of Energy Office of Nuclear Energy, Science and Technology]
* [http://www.engr.utk.edu/nuclear/colloquia/slides/Gen%20IV%20U-Tenn%20Presentation.pdf Gen IV presentation]
* [http://www.ecology.at/ecology/files/pr577_1.pdf Science or Fiction - Is there a Future for Nuclear?] (Nov. 2007) - A publication from the Austrian [[Ecology Institute (Austria)|Ecology Institute]] about 'Generation IV' and Fusion reactors.
* {{cite web |url=http://memagazine.asme.org/Articles/2011/December/Nuclear_Power_After_Fukushima.cfm |title=Nuclear Power After Fukushima |author=Gail H. Marcus |date=December 2011 |work=Mechanical Engineering (the magazine of [[ASME]]) |accessdate=23 January 2012}} "In the wake of a severe plant accident, advanced reactor designs are getting renewed attention."
* [http://www.itheo.org/ International Thorium Energy Organisation - www.IThEO.org]
* [http://www.ithec.org/ International Thorium Energy Committee - iThEC]

{{Nuclear fission reactors}}

[[Category:Nuclear power reactor types]]
[[Category:Idaho National Laboratory]]

Benutzer:Snackroeg/Kernreaktoren der Generation 5

2016-10-27T06:41:27Z

Boundarylayer: /* Reactor types */ Provided an example of a GFR design, the Energy Multiplier Module

[[File:GenIVRoadmap-en.svg|thumb|480px|Nuclear Energy Systems Deployable no later than 2030 and offering significant advances in sustainability, safety and reliability, and economics]]

'''Generation IV reactors''' ('''Gen IV''') are a set of [[nuclear reactor]] designs currently being researched for commercial applications by the Generation IV International Forum, with [[Technology readiness level]]s varying between the level requiring a demonstration, to economical competitive implementation. They are motivated by a variety of goals including improved safety, sustainability, efficiency, and cost.

Most of these designs are generally not expected to be available for commercial construction before 2030–40.<ref name="Generation IV">[http://www.world-nuclear.org/info/Nuclear-Fuel-Cycle/Power-Reactors/Generation-IV-Nuclear-Reactors/]</ref> Presently the majority of reactors in operation around the world are considered [[Generation II reactor|second generation reactor]] systems, as the vast majority of the [[Generation I reactor|first-generation]] systems were retired some time ago, and there are only a dozen or so [[Generation III reactor]]s in operation (2014). [[Nuclear reactor#Generation V+ reactors|Generation V reactors]] refer to reactors that are purely theoretical and are therefore not yet considered feasible in the short term, resulting in limited [[R&D]] funding.

== History ==
The Generation IV International Forum (GIF) is "a co-operative international endeavour which was set up to carry out the research and development needed to establish the feasibility and performance capabilities of the next generation nuclear energy systems."<ref>{{Cite web|url=https://www.gen-4.org/gif/jcms/c_9260/public|title=GIF Portal - Home - Public|website=www.gen-4.org|access-date=2016-07-25}}</ref> It was founded in 2001. There are currently ten active members of the Generation IV International Forum (GIF): [[Canada]], [[China]], the [[European Atomic Energy Community]] (Euratom), [[France]], [[Japan]], [[Russia]], [[South Africa]], [[South Korea]], [[Switzerland]], and the [[United States]]. The non-active members are [[Argentina]], [[Brazil]], and the [[United Kingdom]].<ref name="gen-4">{{cite web|url=https://www.gen-4.org/gif/jcms/c_9492/members|title=GIF Membership|website=gen-4.org|accessdate=28 October 2014}}</ref> Switzerland joined in 2002, Euratom in 2003, and China and Russia in 2006. The remaining countries (excluding Australia) were founding members.<ref name="gen-4" />

The 36th GIF meeting in [[Brussels]] was held in November 2013.<ref>{{cite web|url=http://www.energy.gov/ne/articles/generation-iv-international-forum-updates-technology-roadmap-and-builds-future|title=generation IV international forum updates technology roadmap and builds future. DOE}}</ref><ref>{{cite web|url=http://events.r20.constantcontact.com/register/event?llr=mscrkjkab&oeidk=a07e7melf609716b2c6|title=The Generation IV international forum holds their 36th meeting on Monday 18th Nov 2013 in Brussels.}}</ref> The ''Technology Roadmap Update for Generation IV Nuclear Energy Systems'' was published in January 2014 which details R&D objectives for the next decade.<ref>[https://web.archive.org/web/20140625102915/https://www.gen-4.org/gif/upload/docs/application/pdf/2014-03/gif-tru2014.pdf Technology Roadmap Update for Generation IV Nuclear Energy Systems]</ref> A breakdown of the reactor designs being researched by each forum member has been made available.<ref>[https://web.archive.org/web/20140708023538/https://www.gen-4.org/gif/upload/docs/application/pdf/2014-03/gif_overview_presentation_v9_final3_web.pdf Generation IV International Forum, overview, John E. Kelly, page 15]</ref>

[[Nuclear power in Australia|Australia]] joined the forum in 2016.<ref>http://archive.is/22e5F</ref>

== Reactor types ==
Many reactor types were considered initially; however, the list was downsized to focus on the most promising technologies and those that could most likely meet the goals of the Gen IV initiative.<ref name="Generation IV"/> Three systems are nominally [[thermal reactor]]s and three are [[fast reactor]]s. The Very High Temperature Reactor (VHTR) is also being researched for potentially providing high quality process heat for [[thermochemical cycle|hydrogen production]]. The fast reactors offer the possibility of burning [[actinides]] to further reduce waste and of being able to "[[breeder reactor|breed more fuel]]" than they consume. These systems offer significant advances in sustainability, safety and reliability, economics, proliferation resistance (depending on perspective) and physical protection.

{| class=wikitable
|-
! System
! Neutron Spectrum
! Coolant
! Temperature (°C)
! Fuel Cycle
! Size (MW)
!Example developers
|-
| [[Very high temperature reactor|VHTR]]
| Thermal
| Helium
| 900–1000
| Open
| 250–300
|[[Japan Atomic Energy Agency|JAEA]] ([[HTTR]]), [[Tsinghua University]] ([[HTR-10]]), X-energy<ref name="energy.gov">{{cite web|title=Energy Department Announces New Investments in Advanced Nuclear Power Reactors...|url=http://www.energy.gov/articles/energy-department-announces-new-investments-advanced-nuclear-power-reactors-help-meet|website=[[United States Department of Energy|US Department of Energy]]|accessdate=16 January 2016}}</ref>
|-
| [[Sodium-cooled fast reactor|SFR]]
| Fast
| Sodium
| 550
| Closed
| 30–150, 300–1500, 1000–2000
|[[TerraPower]] ([[Traveling wave reactor|TWR]]), Toshiba ([[Toshiba 4S|4S]]), [[GE Hitachi Nuclear Energy]] ([[PRISM (reactor)|PRISM]])
|-
| [[Supercritical water reactor|SCWR]]
| Thermal/fast
| Water
| 510–625
| Open/closed
| 300–700, 1000–1500
|
|-
| [[Gas-cooled fast reactor|GFR]]
| Fast
| Helium
| 850
| Closed
| 1200
|[[Energy Multiplier Module]]
|-
| [[Lead-cooled fast reactor|LFR]]
| Fast
| Lead
| 480–800
| Closed
| 20–180, 300–1200, 600–1000
|
|-
| [[Molten salt reactor|MSR]]
| Fast/thermal
| Fluoride/Chloride salts
| 700–800
| Closed
| 250, 1000
|[[Flibe Energy]] ([[Liquid fluoride thorium reactor|LFTR]]), [[Transatomic Power]], Thorium Tech Solution ([[Fuji Molten Salt Reactor|FUJI MSR]]), Terrestrial Energy ([[IMSR]]), [[Southern Company Services|Southern Company]]<ref name="energy.gov"/>
|}
<ref>https://www.gen-4.org/gif/upload/docs/application/pdf/2013-09/gif_rd_outlook_for_generation_iv_nuclear_energy_systems.pdf</ref>

=== Thermal reactors ===
A [[Thermal-neutron reactor|thermal reactor]] is a [[nuclear reactor]] that uses slow or [[thermal neutrons]]. A [[neutron moderator]] is used to slow the [[neutron]]s emitted by fission to make them more likely to be captured by the fuel.

==== Very-high-temperature reactor (VHTR) ====
[[File:Very High Temperature Reactor.svg|right|thumb|Very-High-Temperature Reactor (VHTR)]]
{{Main article|Very high temperature reactor}}
{{see also|Fort St. Vrain Generating Station|HTTR|HTR-10}}
The '''very high temperature reactor''' concept uses a [[graphite]]-moderated core with a once-through [[uranium]] fuel cycle, using helium or molten salt as the [[Very high temperature reactor#Coolant|coolant]]. This reactor design envisions an outlet temperature of 1,000 °C. The reactor core can be either a prismatic-block or a [[pebble bed reactor]] design. The high temperatures enable applications such as process heat or [[hydrogen]] production via the thermochemical [[Sulfur-iodine cycle|iodine-sulfur]] process. It would also be [[Passive nuclear safety|passively safe]].

The planned construction of the first VHTR, the South African PBMR ([[pebble bed modular reactor]]), lost government funding in February, 2010.<ref>[http://www.powergenworldwide.com/index/display/articledisplay/6322207443/articles/power-engineering-international/volume-18/Issue_3/regulars/world-news/INTERNATIONAL.html South Africa to stop funding Pebble Bed nuclear reactor]</ref> A pronounced increase of costs and concerns about possible unexpected technical problems had discouraged potential investors and customers.

The [[Peoples Republic of China]] began construction of a 200-MW High Temperature Pebble bed reactor in 2012 as a successor to its [[HTR-10]].<ref>[http://www.nucnet.org/all-the-news/2013/01/07/china-begins-construction-of-first-generation-iv-htr-pm-unit Nucnet Report: 'China Begins Construction of First Generation IV HTR-PM Unit', 7 January 2013]</ref>

Also in 2012, as part of the [[Next Generation Nuclear Plant]] competition, [[Idaho National Laboratory]] approved a design similar to [[Areva]]'s prismatic block [http://us.areva.com/EN/home-3225/areva-inc-areva-htgr.html Antares reactor] as the chosen [[HTGR]] to be deployed as a prototype by 2021. It was in competition with [[General Atomics]]' [[Gas turbine modular helium reactor]] and [[Westinghouse Electric Company|Westinghouse]]'s [[Pebble Bed Modular Reactor]].<ref name="World nuclear news">{{cite web|url=http://www.world-nuclear-news.org/NN-Areva_modular_reactor_selected_for_NGNP_development-1502124.html|title=INL approves Antares design}}</ref>

==== Molten-salt reactor (MSR) ====
[[File:Molten Salt Reactor.svg|right|thumb|Molten Salt Reactor (MSR)]]
{{Main article|Molten salt reactor}}
{{see also|Liquid fluoride thorium reactor}}
A '''molten salt reactor'''<ref name="Roadmap"/> is a type of [[nuclear reactor]] where the primary [[coolant]], or even the fuel itself is a molten salt mixture. There have been many designs put forward for this type of reactor and a few prototypes built. The early concepts and many current ones rely on [[nuclear fuel]] dissolved in the molten [[fluoride]] salt as [[uranium tetrafluoride]] (UF4) or [[thorium tetrafluoride]] (ThF4). The fluid would reach [[Nuclear reactor physics#Criticality|criticality]] by flowing into a [[graphite]] core which would also serve as the [[neutron moderator|moderator]]. Many current concepts rely on fuel that is dispersed in a graphite matrix with the molten salt providing low pressure, high temperature cooling.

The Gen IV MSR is more accurately termed an [[epithermal neutron|epithermal reactor]] than a thermal reactor due to the average speed of the neutrons that would cause the fission events within its fuel being faster than [[thermal neutron]]s.<ref>{{cite web |url=https://inlportal.inl.gov/portal/server.pt?open=514&objID=1361&parentname=CommunityPage&parentid=10&mode=2&in_hi_userid=200&cached=true |title=Idaho National Laboratory detailing some current efforts at developing Gen. IV reactors}}</ref>

The principle of a MSR can be used for thermal, epithermal and fast reactors. Since 2005 the focus has moved towards a fast spectrum MSR (MSFR).<ref>H. Boussier, S. Delpech, V. Ghetta et Al. : The Molten Salt Reactor (MSR) in Generation IV: Overview and Perspectives, GIF SYMPOSIUM PROCEEDINGS/2012 ANNUAL REPORT, NEA No. 7141, pp95 [https://www.gen-4.org/gif/jcms/c_44720/annual-reports]
</ref>

While most MSR designs being pursued are largely derived from the 1960s [[Molten-Salt Reactor Experiment]](MSRE), variants of molten salt technology include the conceptual ''[[Dual fluid reactor]]'' which is being designed with lead as a cooling medium but molten salt fuel, commonly as the metal chloride e.g [[Plutonium(III) chloride]], to aid in greater "nuclear waste" closed-fuel cycle capabilities.
Other notable approaches differing substantially from those with MSRE [[pedigree]] include the ''Stable Salt Reactor''(SSR) concept promoted by MOLTEX, which encases the molten salt in hundreds of the common solid [[fuel rod]]s that are already well established in the nuclear industry. This latter British design was found to be the most competitive for [[Small modular reactor]] development by a British based consultancy firm ''Energy Process Development'' in 2015.<ref>[http://www.daretothink.org/europe-moltex-stable-salt-reactor/ Europe: Moltex’ Stable Salt Reactor]</ref><ref>[http://analysis.nuclearenergyinsider.com/moltex-energy-sees-uk-canada-smr-licensing-springboard-asia Moltex Energy sees UK, Canada SMR licensing as springboard to Asia Jun 28, 2016]</ref>

==== Supercritical-water-cooled reactor (SCWR) ====
[[File:Supercritical-Water-Cooled Reactor.svg|right|thumb|Supercritical-Water-Cooled Reactor (SCWR)]]
{{Main article|Supercritical water reactor}}
The '''supercritical water reactor''' (SCWR)<ref name="Roadmap"/> is a [[reduced moderation water reactor]] concept that, due to the average speed of the neutrons that would cause the fission events within the fuel being faster than [[thermal neutron]]s, it is more accurately termed an [[epithermal neutron|epithermal reactor]] than a thermal reactor. It uses [[supercritical fluid|supercritical water]] as the working fluid. SCWRs are basically [[light water reactor]]s (LWR) operating at higher pressure and temperatures with a direct, once-through heat exchange cycle. As most commonly envisioned, it would operate on a direct cycle, much like a boiling water reactor ([[BWR]]), but since it uses supercritical water (not to be confused with [[Critical mass (nuclear)|critical mass]]) as the working fluid, it would have only one water phase present, which makes the supercritical heat exchange method more similar to a pressurized water reactor ([[Pressurized water reactor|PWR]]). It could operate at much higher temperatures than both current PWRs and BWRs.

Supercritical water-cooled reactors (SCWRs) are promising advanced nuclear systems because of their high [[thermal efficiency]] (i.e., about 45% vs. about 33% efficiency for current LWRs) and considerable plant simplification.

The main mission of the SCWR is generation of low-cost [[electricity]]. It is built upon two proven technologies, LWRs, which are the most commonly deployed power generating reactors in the world, and superheated [[fossil fuel]] fired [[boiler]]s, a large number of which are also in use around the world. The SCWR concept is being investigated by 32 organizations in 13 countries.{{citation needed|date=October 2012}}

A SCWR Design under development is the [[VVER]]-1700/393 (VVER-SCWR or VVER-SKD) — a Russian Supercritical-water-cooled reactor with double-inlet-core and a [[breeder reactor|breeding ratio]] of 0.95.<ref name="powertecrussia.com">{{cite web |url=http://www.powertecrussia.com/blog/tag/nuclear-power/ |title=Technology Developments & Plant Efficiency for the Russian Nuclear Power Generation Market Wednesday |date=March 24, 2010}}</ref>

=== Fast reactors ===
A [[Fast-neutron reactor|fast reactor]] directly uses the fast neutrons emitted by fission, without moderation. Unlike thermal neutron reactors, fast neutron reactors can be configured to "'''burn'''", or fission, all [[actinides]], and given enough time, therefore drastically reduce the actinides fraction in [[spent nuclear fuel]] produced by the present world fleet of thermal neutron [[light water reactor]]s, thus closing the [[nuclear fuel cycle]]. Alternatively, if configured differently, they can also [[breeder reactor|'''breed''']] more actinide fuel than they consume.

==== Gas-cooled fast reactor (GFR) ====
[[File:Gas-Cooled Fast Reactor Schemata.svg|right|thumb|Gas-Cooled Fast Reactor (GFR)]]
{{Main article|Gas-cooled fast reactor}}
The '''gas-cooled fast reactor''' (GFR)<ref name="Roadmap"/> system features a fast-neutron spectrum and closed fuel cycle for efficient conversion of [[Fertile material|fertile uranium]] and management of actinides. The reactor is [[helium]]-cooled and with an outlet temperature of 850 °C it is an evolution of the [[very-high-temperature reactor]] (VHTR) to a more sustainable fuel cycle. It will use a direct [[Brayton cycle]] [[Closed-cycle gas turbine|gas turbine]] for high thermal efficiency. Several fuel forms are being considered for their potential to operate at very high temperatures and to ensure an excellent retention of [[Nuclear fission|fission]] products: composite [[ceramic]] fuel, advanced fuel particles, or ceramic clad elements of actinide compounds. Core configurations are being considered based on pin- or plate-based fuel assemblies or prismatic blocks.

The European Sustainable Nuclear Industrial Initiative is funding three Generation IV reactor systems, one of which is a gas-cooled fast reactor, called ''Allegro'', 100 MW(t), which will be built in a central or eastern European country with construction expected to begin in 2018.<ref name="euronuclear.org">{{cite web |url=https://www.euronuclear.org/1-information/news/Gen-IV.htm |title=The European Sustainable Nuclear Industrial Initiative (ESNII) will support three Generation IV reactor systems: a sodium-cooled fast reactor, or SFR, called ''Astrid'' that is proposed by France; a gas-cooled fast reactor, GFR, called ''Allegro'' supported by central and eastern Europe; and a lead-cooled fast reactor, LFR, technology pilot called ''Myrrha'' that is proposed by Belgium.}}</ref> The central European [[Visegrád Group]] are committed to pursuing the technology.<ref>{{cite web |url=http://www.alphagalileo.org/ViewItem.aspx?ItemId=133111&CultureCode=en |title=The V4G4 Centre of Excellence for performing joint research, development and innovation in the field of Generation-4 (G4) nuclear reactors have been established. 20 July 2013 National Center for Nuclear Research (NCBJ]}}</ref> In 2013 German, British, and French institutes finished a 3-year collaboration study on the follow on industrial scale design, known as ''GoFastR''.<ref>{{cite web |url=http://www.ist-world.org/ProjectDetails.aspx?ProjectId=5cb8f3f283574cc6b2bdbf72533172d8 |title=the European Gas cooled Fast Reactor.}}</ref> They were funded by the EU's 7th FWP [[framework programme]], with the goal of making a sustainable VHTR.<ref>{{cite web |url=http://www.2020-horizon.com/GOFASTR-European-Gas-Cooled-Fast-Reactor%28GOFASTR%29-s312.html |title=The GOFASTR research program}}</ref>

==== Sodium-cooled fast reactor (SFR) ====
[[File:Sodium-Cooled Fast Reactor Schemata.svg|right|thumb|Pool design Sodium-Cooled Fast Reactor (SFR)]]
{{Main article|Sodium-cooled fast reactor}}
{{see also|Experimental Breeder Reactor II|S-PRISM|BN-800 reactor|Toshiba 4S}}
The SFR<ref name="Roadmap"/> is a project that builds on two closely related existing projects, the liquid metal [[Breeder reactor#Fast breeder reactor|fast breeder reactor]] and the [[integral fast reactor]].

The goals are to increase the efficiency of uranium usage by [[breeder reactor|breeding]] plutonium and eliminating the need for [[transuranic]] isotopes ever to leave the site. The reactor design uses an unmoderated core running on [[fast neutron]]s, designed to allow any transuranic isotope to be consumed (and in some cases used as fuel). In addition to the benefits of removing the long [[half-life]] transuranics from the waste cycle, the SFR fuel expands when the reactor overheats, and the chain reaction automatically slows down. In this manner, it is passively safe.<ref>{{cite web |url=http://www.ne.anl.gov/About/hn/logos-winter02-psr.shtml|title=Passively safe reactors rely on nature to keep them cool|author=David Baurac}}</ref>

The SFR reactor concept is cooled by liquid [[sodium]] and fueled by a metallic alloy of uranium and [[plutonium]] or [[spent nuclear fuel]], the "nuclear waste" of [[light water reactor]]s. The SFR fuel is contained in steel cladding with liquid sodium filling in the space between the clad elements which make up the fuel assembly. One of the design challenges of an SFR is the risks of handling sodium, which reacts explosively if it comes into contact with water. However, the use of liquid metal instead of water as coolant allows the system to work at atmospheric pressure, reducing the risk of leakage.

The European Sustainable Nuclear Industrial Initiative is funding three Generation IV reactor systems, one of which is a sodium-cooled fast reactor, called ''[[ASTRID (reactor)|ASTRID]]'', Advanced Sodium Technical Reactor for Industrial Demonstration, [[Areva]], [[Commissariat à l'énergie atomique et aux énergies alternatives|CEA]] and [[Électricité de France|EDF]] are leading the design with British collaboration.<ref>{{cite web |url=http://www.power-eng.com/articles/2010/11/areva--cea-secure.html |title=Areva, CEA secure EUR650m funding to develop ASTRID sodium-cooled Generation IV reactor 11/11/2010}}</ref><ref>{{cite web |url=http://www.powermag.com/uk-and-france-sign-landmark-civil-nuclear-cooperation-agreement/ |title=UK and France Sign Landmark Civil Nuclear Cooperation Agreement 02/22/2012 . POWERnews}}</ref> Astrid will be rated about 600 MWe and is proposed to be built in France, near to the [[Phénix]] reactor. A final decision in construction is to be made in 2019<ref name="euronuclear.org"/>

The [[China|PRC]]'s first commercial-scale, 800 MWe, fast neutron reactor, to be situated near [[Sanming]] in [[Fujian province]] will be a SFR. In 2009 an agreement was signed that would entail the Russian [[BN-800 reactor]] design to be sold to the PRC once it is completed, this would be the first time commercial-scale fast neutron reactors have ever been exported.<ref>{{cite web |url=http://www.world-nuclear-news.org/C-Joint_venture_launched_for_Chinese_fast_reactor-3004104.html |title=Joint venture launched for Chinese fast reactor}}</ref> The BN-800 reactor became operational in 2014.

In India, the [[Prototype Fast Breeder Reactor]], a 500 MWe Sodium cooled fast reactor is being built at a cost of INR 5,677 crores (~US$900 million) and is expected to be commissioned by September 2016. The PFBR will be followed by six more Commercial Fast Breeder Reactors (CFBRs) of 500 MWe each.

The 400 MWe [[Fast Flux Test Facility]] operated successfully for ten years at the Hanford site in Washington State.

The 20 MWe [[EBR II]] operated successfully for over thirty years at the Idaho National Laboratory, until it was shut down in 1994.

==== Lead-cooled fast reactor (LFR) ====
[[File:Lead-Cooled Fast Reactor Schemata.svg|right|thumb|Lead-Cooled Fast Reactor (LFR)]]
{{Main article|Lead-cooled fast reactor}}
{{See also|MYRRHA}}
The '''lead-cooled fast reactor'''<ref name="Roadmap">{{cite journal| year=2002 | title=A Technology Roadmap for Generation IV Nuclear Energy Systems | last=US DOE Nuclear Energy Research Advisory Committee |volume=GIF-002-00|url=http://nuclear.energy.gov/genIV/documents/gen_iv_roadmap.pdf}}</ref> features a fast-neutron-spectrum [[lead]] or [[lead]]/[[bismuth]] [[eutectic]] ([[Lead-bismuth eutectic|LBE]]) liquid-metal-cooled reactor with a closed [[Nuclear fuel cycle|fuel cycle]]. Options include a range of plant ratings, including a "battery" of 50 to 150 MW of electricity that features a very long refueling interval, a modular system rated at 300 to 400 MW, and a large monolithic plant option at 1,200 MW. (The term ''battery'' refers to the long-life, factory-fabricated core, not to any provision for electrochemical energy conversion.) The fuel is metal or nitride-based containing [[Fertile material|fertile uranium]] and [[transuranic]]s. The LFR is cooled by natural [[convection]] with a reactor outlet coolant temperature of 550 °C, possibly ranging up to 800 °C with advanced materials. The higher temperature enables the production of [[Thermochemical cycle|hydrogen by thermochemical processes]].

The European Sustainable Nuclear Industrial Initiative is funding three Generation IV reactor systems, one of which is a lead-cooled fast reactor that is also an [[Subcritical reactor|accelerator-driven sub-critical]] reactor, called ''[[MYRRHA]]'', 100 MW(t), which will be built in [[Belgium]] with construction expected to begin after 2014 and the industrial scale version, known as ''Alfred'', slated to be constructed sometime after 2017. A reduced-power model of Myrrha called ''Guinevere'' was started up at [[Mol, Belgium|Mol]] in March 2009.<ref name="euronuclear.org"/> In 2012 the research team reported that Guinevere was operational.<ref>{{cite news|last1=Hellemans|first1=Alexander|title=Reactor-Accelerator Hybrid Achieves Successful Test Run|url=http://news.sciencemag.org/physics/2012/01/reactor-accelerator-hybrid-achieves-successful-test-run|accessdate=29 December 2014|work=Science Insider|date=12 January 2012}}</ref>

Two other lead-cooled fast reactors under development are the SVBR-100, a modular 100 MWe lead-bismuth cooled fast neutron reactor concept designed by OKB [[Gidropress]] in Russia and the [[BREST (Reactor)|BREST-OD-300]] (Lead-cooled fast reactor) 300 MWe, to be developed after the SVBR-100, and built over 2016-20, it will dispense with the [[Uranium-238|fertile blanket]] around the core and will supersede the sodium cooled [[BN-600 reactor]] design, to purportedly give enhanced proliferation resistance.<ref name="powertecrussia.com"/>

== Advantages and disadvantages ==
Relative to current nuclear power plant technology, the claimed benefits for 4th generation reactors include:
* Nuclear waste that remains radioactive for a few centuries instead of millennia<ref>{{cite web |title=Strategies to Address Global Warming |url=http://www.columbia.edu/~jeh1/mailings/2009/20090713_Strategies.pdf}}</ref>
* 100-300 times more energy yield from the same amount of nuclear fuel<ref>{{cite web |title=4th Generation Nuclear Power |url=http://www.ossfoundation.us/projects/energy/nuclear}}</ref>
* Broader range of fuels, and even unencapsulated raw fuels (non-pebble [[Molten Salt Reactor|MSR]], [[LFTR]]).
* In some reactors, the ability to consume existing nuclear waste in the production of electricity, that is, a Closed [[nuclear fuel cycle]]. This strengthens the argument to deem [[nuclear power as renewable energy]].
* Improved operating safety features, such as (depending on design) avoidance of pressurized operation, automatic passive (unpowered, uncommanded) reactor shutdown, avoidance of water cooling and the associated risks of loss of water (leaks or boiling) and hydrogen generation/explosion and contamination of coolant water.

Nuclear reactors do not emit CO2 during operation, although like all [[low carbon power]] sources, the mining and construction phase can result in CO2 emissions, if energy sources which are not carbon neutral (such as fossil fuels), or CO2 emitting cements are used during the construction process.
A 2012 [[Yale University]] review published in the Journal of Industrial Ecology analyzing {{CO2}} [[life cycle assessment]] (LCA) emissions from [[nuclear power]] determined that:<ref name="Warner + Heath, JoIE">Warner, Ethan S.; Heath, Garvin A. [http://onlinelibrary.wiley.com/doi/10.1111/j.1530-9290.2012.00472.x/full Life Cycle Greenhouse Gas Emissions of Nuclear Electricity Generation: Systematic Review and Harmonization], ''Journal of Industrial Ecology'', [[Yale University]], published online April 17, 2012, doi: 10.1111/j.1530-9290.2012.00472.x.</ref>
{{Quote|''"The collective LCA literature indicates that life cycle [[Greenhouse gas|GHG]] [ greenhouse gas ] emissions from nuclear power are only a fraction of traditional fossil sources and comparable to renewable technologies."''}}
Although the paper primarily dealt with data from [[Generation II reactor]]s, and did not analyze the {{CO2}} emissions by 2050 of the presently under construction [[Generation III reactor]]s, it did summarize the Life Cycle Assessment findings of in development reactor technologies.''{{Quote|FBRs ''[ [[Fast Breeder Reactor]]s ]'' have been evaluated in the LCA literature. The limited literature that evaluates this potential future technology reports [[median]] life cycle GHG emissions... similar to or lower than LWRs[ Gen II [[light water reactor]]s ] and purports to consume little or no [[uranium market|uranium ore]].}}

A specific risk of the sodium-cooled fast reactor is related to using metallic sodium as a coolant. In case of a breach, sodium explosively reacts with water. Fixing breaches may also prove dangerous, as the cheapest noble gas [[argon]] is also used to prevent sodium oxidation. Argon, like helium, can displace oxygen in the air and can pose [[hypoxia (environmental)|hypoxia]] concerns, so workers may be exposed to this additional risk. This is a pertinent problem as can be testified by the events at the [[LMFBR|loop type]] [[Monju Nuclear Power Plant|Prototype Fast Breeder Reactor Monju]] at Tsuruga, Japan.<ref>{{cite news |title=Japan Strains to Fix a Reactor Damaged Before Quake |url=http://www.nytimes.com/2011/06/18/world/asia/18japan.html | work=The New York Times | first=Hiroko |last=Tabuchi |date=17 June 2011}}</ref>
Using lead or molten salts mitigates this problem by making the coolant less reactive and allowing a high freezing temperature and low pressure in case of a leak. Disadvantages of lead compared to sodium are much higher viscosity, much higher density, lower heat capacity, and more radioactive neutron activation products.

In many cases, there is already a large amount of experience built up with numerous proof of concept Gen IV designs. For example, the reactors at [[Fort St. Vrain Generating Station]] and [[HTR-10]] are similar to the proposed Gen IV [[VHTR]] designs, and the [[LMFBR|pool type]] [[EBR-II]], [[Phénix]] and [[BN-600]] reactor are similar to the proposed pool type Gen IV Sodium Cooled Fast reactors being designed.

== See also ==
{{colbegin|3}}
* [[Nuclear reactor]]
* [[Nuclear material]]
* [[Nuclear physics]]
* [[List of reactor types#Reactor types|List of reactor types]]
* [[Generation II reactor]]
* [[Generation III reactor]]
* [[Integral Fast Reactor]]
* [[Liquid fluoride thorium reactor]]
* [[Breeder reactor]]
* [[Small modular reactor]]
{{colend}}

==References==
{{Reflist|30em}}

== External links ==
* [https://inlportal.inl.gov/portal/server.pt?open=514&objID=1361&parentname=CommunityPage&parentid=10&mode=2&in_hi_userid=200&cached=true Article from Idaho National Laboratory detailing some current efforts at developing Gen. IV reactors.]
* [http://www.gen-4.org/ Generation IV International Forum (GIF)]
* [http://nuclear.energy.gov/genIV/neGenIV1.html U.S. Department of Energy Office of Nuclear Energy, Science and Technology]
* [http://www.engr.utk.edu/nuclear/colloquia/slides/Gen%20IV%20U-Tenn%20Presentation.pdf Gen IV presentation]
* [http://www.ecology.at/ecology/files/pr577_1.pdf Science or Fiction - Is there a Future for Nuclear?] (Nov. 2007) - A publication from the Austrian [[Ecology Institute (Austria)|Ecology Institute]] about 'Generation IV' and Fusion reactors.
* {{cite web |url=http://memagazine.asme.org/Articles/2011/December/Nuclear_Power_After_Fukushima.cfm |title=Nuclear Power After Fukushima |author=Gail H. Marcus |date=December 2011 |work=Mechanical Engineering (the magazine of [[ASME]]) |accessdate=23 January 2012}} "In the wake of a severe plant accident, advanced reactor designs are getting renewed attention."
* [http://www.itheo.org/ International Thorium Energy Organisation - www.IThEO.org]
* [http://www.ithec.org/ International Thorium Energy Committee - iThEC]

{{Nuclear fission reactors}}

[[Category:Nuclear power reactor types]]
[[Category:Idaho National Laboratory]]

Benutzer:Snackroeg/Kernreaktoren der Generation 5

2016-10-20T02:53:24Z

Boundarylayer: /* Reactor types */

[[File:GenIVRoadmap-en.svg|thumb|480px|Nuclear Energy Systems Deployable no later than 2030 and offering significant advances in sustainability, safety and reliability, and economics]]

'''Generation IV reactors''' ('''Gen IV''') are a set of [[nuclear reactor]] designs currently being researched for commercial applications by the Generation IV International Forum, with [[Technology readiness level]]s varying between the level requiring a demonstration, to economical competitive implementation. They are motivated by a variety of goals including improved safety, sustainability, efficiency, and cost.

Most of these designs are generally not expected to be available for commercial construction before 2030–40.<ref name="Generation IV">[http://www.world-nuclear.org/info/Nuclear-Fuel-Cycle/Power-Reactors/Generation-IV-Nuclear-Reactors/]</ref> Presently the majority of reactors in operation around the world are considered [[Generation II reactor|second generation reactor]] systems, as the vast majority of the [[Generation I reactor|first-generation]] systems were retired some time ago, and there are only a dozen or so [[Generation III reactor]]s in operation (2014). [[Nuclear reactor#Generation V+ reactors|Generation V reactors]] refer to reactors that are purely theoretical and are therefore not yet considered feasible in the short term, resulting in limited [[R&D]] funding.

== History ==
The Generation IV International Forum (GIF) is "a co-operative international endeavour which was set up to carry out the research and development needed to establish the feasibility and performance capabilities of the next generation nuclear energy systems."<ref>{{Cite web|url=https://www.gen-4.org/gif/jcms/c_9260/public|title=GIF Portal - Home - Public|website=www.gen-4.org|access-date=2016-07-25}}</ref> It was founded in 2001. There are currently ten active members of the Generation IV International Forum (GIF): [[Canada]], [[China]], the [[European Atomic Energy Community]] (Euratom), [[France]], [[Japan]], [[Russia]], [[South Africa]], [[South Korea]], [[Switzerland]], and the [[United States]]. The non-active members are [[Argentina]], [[Brazil]], and the [[United Kingdom]].<ref name="gen-4">{{cite web|url=https://www.gen-4.org/gif/jcms/c_9492/members|title=GIF Membership|website=gen-4.org|accessdate=28 October 2014}}</ref> Switzerland joined in 2002, Euratom in 2003, and China and Russia in 2006. The remaining countries (excluding Australia) were founding members.<ref name="gen-4" />

The 36th GIF meeting in [[Brussels]] was held in November 2013.<ref>{{cite web|url=http://www.energy.gov/ne/articles/generation-iv-international-forum-updates-technology-roadmap-and-builds-future|title=generation IV international forum updates technology roadmap and builds future. DOE}}</ref><ref>{{cite web|url=http://events.r20.constantcontact.com/register/event?llr=mscrkjkab&oeidk=a07e7melf609716b2c6|title=The Generation IV international forum holds their 36th meeting on Monday 18th Nov 2013 in Brussels.}}</ref> The ''Technology Roadmap Update for Generation IV Nuclear Energy Systems'' was published in January 2014 which details R&D objectives for the next decade.<ref>[https://web.archive.org/web/20140625102915/https://www.gen-4.org/gif/upload/docs/application/pdf/2014-03/gif-tru2014.pdf Technology Roadmap Update for Generation IV Nuclear Energy Systems]</ref> A breakdown of the reactor designs being researched by each forum member has been made available.<ref>[https://web.archive.org/web/20140708023538/https://www.gen-4.org/gif/upload/docs/application/pdf/2014-03/gif_overview_presentation_v9_final3_web.pdf Generation IV International Forum, overview, John E. Kelly, page 15]</ref>

[[Nuclear power in Australia|Australia]] joined the forum in 2016.<ref>http://archive.is/22e5F</ref>

== Reactor types ==
Many reactor types were considered initially; however, the list was downsized to focus on the most promising technologies and those that could most likely meet the goals of the Gen IV initiative.<ref name="Generation IV"/> Three systems are nominally [[thermal reactor]]s and three are [[fast reactor]]s. The Very High Temperature Reactor (VHTR) is also being researched for potentially providing high quality process heat for [[thermochemical cycle|hydrogen production]]. The fast reactors offer the possibility of burning [[actinides]] to further reduce waste and of being able to "[[breeder reactor|breed more fuel]]" than they consume. These systems offer significant advances in sustainability, safety and reliability, economics, proliferation resistance (depending on perspective) and physical protection.

{| class=wikitable
|-
! System
! Neutron Spectrum
! Coolant
! Temperature (°C)
! Fuel Cycle
! Size (MW)
!Example developers
|-
| [[Very high temperature reactor|VHTR]]
| Thermal
| Helium
| 900–1000
| Open
| 250–300
|[[Japan Atomic Energy Agency|JAEA]] ([[HTTR]]), [[Tsinghua University]] ([[HTR-10]]), X-energy<ref name="energy.gov">{{cite web|title=Energy Department Announces New Investments in Advanced Nuclear Power Reactors...|url=http://www.energy.gov/articles/energy-department-announces-new-investments-advanced-nuclear-power-reactors-help-meet|website=[[United States Department of Energy|US Department of Energy]]|accessdate=16 January 2016}}</ref>
|-
| [[Sodium-cooled fast reactor|SFR]]
| Fast
| Sodium
| 550
| Closed
| 30–150, 300–1500, 1000–2000
|[[TerraPower]] ([[Traveling wave reactor|TWR]]), Toshiba ([[Toshiba 4S|4S]]), [[GE Hitachi Nuclear Energy]] ([[PRISM (reactor)|PRISM]])
|-
| [[Supercritical water reactor|SCWR]]
| Thermal/fast
| Water
| 510–625
| Open/closed
| 300–700, 1000–1500
|
|-
| [[Gas-cooled fast reactor|GFR]]
| Fast
| Helium
| 850
| Closed
| 1200
|
|-
| [[Lead-cooled fast reactor|LFR]]
| Fast
| Lead
| 480–800
| Closed
| 20–180, 300–1200, 600–1000
|
|-
| [[Molten salt reactor|MSR]]
| Fast/thermal
| Fluoride/Chloride salts
| 700–800
| Closed
| 250, 1000
|[[Flibe Energy]] ([[Liquid fluoride thorium reactor|LFTR]]), [[Transatomic Power]], Thorium Tech Solution ([[Fuji Molten Salt Reactor|FUJI MSR]]), Terrestrial Energy ([[IMSR]]), [[Southern Company Services|Southern Company]]<ref name="energy.gov"/>
|}
<ref>https://www.gen-4.org/gif/upload/docs/application/pdf/2013-09/gif_rd_outlook_for_generation_iv_nuclear_energy_systems.pdf</ref>

=== Thermal reactors ===
A [[Thermal-neutron reactor|thermal reactor]] is a [[nuclear reactor]] that uses slow or [[thermal neutrons]]. A [[neutron moderator]] is used to slow the [[neutron]]s emitted by fission to make them more likely to be captured by the fuel.

==== Very-high-temperature reactor (VHTR) ====
[[File:Very High Temperature Reactor.svg|right|thumb|Very-High-Temperature Reactor (VHTR)]]
{{Main article|Very high temperature reactor}}
{{see also|Fort St. Vrain Generating Station|HTTR|HTR-10}}
The '''very high temperature reactor''' concept uses a [[graphite]]-moderated core with a once-through [[uranium]] fuel cycle, using helium or molten salt as the [[Very high temperature reactor#Coolant|coolant]]. This reactor design envisions an outlet temperature of 1,000 °C. The reactor core can be either a prismatic-block or a [[pebble bed reactor]] design. The high temperatures enable applications such as process heat or [[hydrogen]] production via the thermochemical [[Sulfur-iodine cycle|iodine-sulfur]] process. It would also be [[Passive nuclear safety|passively safe]].

The planned construction of the first VHTR, the South African PBMR ([[pebble bed modular reactor]]), lost government funding in February, 2010.<ref>[http://www.powergenworldwide.com/index/display/articledisplay/6322207443/articles/power-engineering-international/volume-18/Issue_3/regulars/world-news/INTERNATIONAL.html South Africa to stop funding Pebble Bed nuclear reactor]</ref> A pronounced increase of costs and concerns about possible unexpected technical problems had discouraged potential investors and customers.

The [[Peoples Republic of China]] began construction of a 200-MW High Temperature Pebble bed reactor in 2012 as a successor to its [[HTR-10]].<ref>[http://www.nucnet.org/all-the-news/2013/01/07/china-begins-construction-of-first-generation-iv-htr-pm-unit Nucnet Report: 'China Begins Construction of First Generation IV HTR-PM Unit', 7 January 2013]</ref>

Also in 2012, as part of the [[Next Generation Nuclear Plant]] competition, [[Idaho National Laboratory]] approved a design similar to [[Areva]]'s prismatic block [http://us.areva.com/EN/home-3225/areva-inc-areva-htgr.html Antares reactor] as the chosen [[HTGR]] to be deployed as a prototype by 2021. It was in competition with [[General Atomics]]' [[Gas turbine modular helium reactor]] and [[Westinghouse Electric Company|Westinghouse]]'s [[Pebble Bed Modular Reactor]].<ref name="World nuclear news">{{cite web|url=http://www.world-nuclear-news.org/NN-Areva_modular_reactor_selected_for_NGNP_development-1502124.html|title=INL approves Antares design}}</ref>

==== Molten-salt reactor (MSR) ====
[[File:Molten Salt Reactor.svg|right|thumb|Molten Salt Reactor (MSR)]]
{{Main article|Molten salt reactor}}
{{see also|Liquid fluoride thorium reactor}}
A '''molten salt reactor'''<ref name="Roadmap"/> is a type of [[nuclear reactor]] where the primary [[coolant]], or even the fuel itself is a molten salt mixture. There have been many designs put forward for this type of reactor and a few prototypes built. The early concepts and many current ones rely on [[nuclear fuel]] dissolved in the molten [[fluoride]] salt as [[uranium tetrafluoride]] (UF4) or [[thorium tetrafluoride]] (ThF4). The fluid would reach [[Nuclear reactor physics#Criticality|criticality]] by flowing into a [[graphite]] core which would also serve as the [[neutron moderator|moderator]]. Many current concepts rely on fuel that is dispersed in a graphite matrix with the molten salt providing low pressure, high temperature cooling.

The Gen IV MSR is more accurately termed an [[epithermal neutron|epithermal reactor]] than a thermal reactor due to the average speed of the neutrons that would cause the fission events within its fuel being faster than [[thermal neutron]]s.<ref>{{cite web |url=https://inlportal.inl.gov/portal/server.pt?open=514&objID=1361&parentname=CommunityPage&parentid=10&mode=2&in_hi_userid=200&cached=true |title=Idaho National Laboratory detailing some current efforts at developing Gen. IV reactors}}</ref>

The principle of a MSR can be used for thermal, epithermal and fast reactors. Since 2005 the focus has moved towards a fast spectrum MSR (MSFR).<ref>H. Boussier, S. Delpech, V. Ghetta et Al. : The Molten Salt Reactor (MSR) in Generation IV: Overview and Perspectives, GIF SYMPOSIUM PROCEEDINGS/2012 ANNUAL REPORT, NEA No. 7141, pp95 [https://www.gen-4.org/gif/jcms/c_44720/annual-reports]
</ref>

While most MSR designs being pursued are largely derived from the 1960s [[Molten-Salt Reactor Experiment]](MSRE), variants of molten salt technology include the conceptual ''[[Dual fluid reactor]]'' which is being designed with lead as a cooling medium but molten salt fuel, commonly as the metal chloride e.g [[Plutonium(III) chloride]], to aid in greater "nuclear waste" closed-fuel cycle capabilities.
Other notable approaches differing substantially from those with MSRE [[pedigree]] include the ''Stable Salt Reactor''(SSR) concept promoted by MOLTEX, which encases the molten salt in hundreds of the common solid [[fuel rod]]s that are already well established in the nuclear industry. This latter British design was found to be the most competitive for [[Small modular reactor]] development by a British based consultancy firm ''Energy Process Development'' in 2015.<ref>[http://www.daretothink.org/europe-moltex-stable-salt-reactor/ Europe: Moltex’ Stable Salt Reactor]</ref><ref>[http://analysis.nuclearenergyinsider.com/moltex-energy-sees-uk-canada-smr-licensing-springboard-asia Moltex Energy sees UK, Canada SMR licensing as springboard to Asia Jun 28, 2016]</ref>

==== Supercritical-water-cooled reactor (SCWR) ====
[[File:Supercritical-Water-Cooled Reactor.svg|right|thumb|Supercritical-Water-Cooled Reactor (SCWR)]]
{{Main article|Supercritical water reactor}}
The '''supercritical water reactor''' (SCWR)<ref name="Roadmap"/> is a [[reduced moderation water reactor]] concept that, due to the average speed of the neutrons that would cause the fission events within the fuel being faster than [[thermal neutron]]s, it is more accurately termed an [[epithermal neutron|epithermal reactor]] than a thermal reactor. It uses [[supercritical fluid|supercritical water]] as the working fluid. SCWRs are basically [[light water reactor]]s (LWR) operating at higher pressure and temperatures with a direct, once-through heat exchange cycle. As most commonly envisioned, it would operate on a direct cycle, much like a boiling water reactor ([[BWR]]), but since it uses supercritical water (not to be confused with [[Critical mass (nuclear)|critical mass]]) as the working fluid, it would have only one water phase present, which makes the supercritical heat exchange method more similar to a pressurized water reactor ([[Pressurized water reactor|PWR]]). It could operate at much higher temperatures than both current PWRs and BWRs.

Supercritical water-cooled reactors (SCWRs) are promising advanced nuclear systems because of their high [[thermal efficiency]] (i.e., about 45% vs. about 33% efficiency for current LWRs) and considerable plant simplification.

The main mission of the SCWR is generation of low-cost [[electricity]]. It is built upon two proven technologies, LWRs, which are the most commonly deployed power generating reactors in the world, and superheated [[fossil fuel]] fired [[boiler]]s, a large number of which are also in use around the world. The SCWR concept is being investigated by 32 organizations in 13 countries.{{citation needed|date=October 2012}}

A SCWR Design under development is the [[VVER]]-1700/393 (VVER-SCWR or VVER-SKD) — a Russian Supercritical-water-cooled reactor with double-inlet-core and a [[breeder reactor|breeding ratio]] of 0.95.<ref name="powertecrussia.com">{{cite web |url=http://www.powertecrussia.com/blog/tag/nuclear-power/ |title=Technology Developments & Plant Efficiency for the Russian Nuclear Power Generation Market Wednesday |date=March 24, 2010}}</ref>

=== Fast reactors ===
A [[Fast-neutron reactor|fast reactor]] directly uses the fast neutrons emitted by fission, without moderation. Unlike thermal neutron reactors, fast neutron reactors can be configured to "'''burn'''", or fission, all [[actinides]], and given enough time, therefore drastically reduce the actinides fraction in [[spent nuclear fuel]] produced by the present world fleet of thermal neutron [[light water reactor]]s, thus closing the [[nuclear fuel cycle]]. Alternatively, if configured differently, they can also [[breeder reactor|'''breed''']] more actinide fuel than they consume.

==== Gas-cooled fast reactor (GFR) ====
[[File:Gas-Cooled Fast Reactor Schemata.svg|right|thumb|Gas-Cooled Fast Reactor (GFR)]]
{{Main article|Gas-cooled fast reactor}}
The '''gas-cooled fast reactor''' (GFR)<ref name="Roadmap"/> system features a fast-neutron spectrum and closed fuel cycle for efficient conversion of [[Fertile material|fertile uranium]] and management of actinides. The reactor is [[helium]]-cooled and with an outlet temperature of 850 °C it is an evolution of the [[very-high-temperature reactor]] (VHTR) to a more sustainable fuel cycle. It will use a direct [[Brayton cycle]] [[Closed-cycle gas turbine|gas turbine]] for high thermal efficiency. Several fuel forms are being considered for their potential to operate at very high temperatures and to ensure an excellent retention of [[Nuclear fission|fission]] products: composite [[ceramic]] fuel, advanced fuel particles, or ceramic clad elements of actinide compounds. Core configurations are being considered based on pin- or plate-based fuel assemblies or prismatic blocks.

The European Sustainable Nuclear Industrial Initiative is funding three Generation IV reactor systems, one of which is a gas-cooled fast reactor, called ''Allegro'', 100 MW(t), which will be built in a central or eastern European country with construction expected to begin in 2018.<ref name="euronuclear.org">{{cite web |url=https://www.euronuclear.org/1-information/news/Gen-IV.htm |title=The European Sustainable Nuclear Industrial Initiative (ESNII) will support three Generation IV reactor systems: a sodium-cooled fast reactor, or SFR, called ''Astrid'' that is proposed by France; a gas-cooled fast reactor, GFR, called ''Allegro'' supported by central and eastern Europe; and a lead-cooled fast reactor, LFR, technology pilot called ''Myrrha'' that is proposed by Belgium.}}</ref> The central European [[Visegrád Group]] are committed to pursuing the technology.<ref>{{cite web |url=http://www.alphagalileo.org/ViewItem.aspx?ItemId=133111&CultureCode=en |title=The V4G4 Centre of Excellence for performing joint research, development and innovation in the field of Generation-4 (G4) nuclear reactors have been established. 20 July 2013 National Center for Nuclear Research (NCBJ]}}</ref> In 2013 German, British, and French institutes finished a 3-year collaboration study on the follow on industrial scale design, known as ''GoFastR''.<ref>{{cite web |url=http://www.ist-world.org/ProjectDetails.aspx?ProjectId=5cb8f3f283574cc6b2bdbf72533172d8 |title=the European Gas cooled Fast Reactor.}}</ref> They were funded by the EU's 7th FWP [[framework programme]], with the goal of making a sustainable VHTR.<ref>{{cite web |url=http://www.2020-horizon.com/GOFASTR-European-Gas-Cooled-Fast-Reactor%28GOFASTR%29-s312.html |title=The GOFASTR research program}}</ref>

==== Sodium-cooled fast reactor (SFR) ====
[[File:Sodium-Cooled Fast Reactor Schemata.svg|right|thumb|Pool design Sodium-Cooled Fast Reactor (SFR)]]
{{Main article|Sodium-cooled fast reactor}}
{{see also|Experimental Breeder Reactor II|S-PRISM|BN-800 reactor|Toshiba 4S}}
The SFR<ref name="Roadmap"/> is a project that builds on two closely related existing projects, the liquid metal [[Breeder reactor#Fast breeder reactor|fast breeder reactor]] and the [[integral fast reactor]].

The goals are to increase the efficiency of uranium usage by [[breeder reactor|breeding]] plutonium and eliminating the need for [[transuranic]] isotopes ever to leave the site. The reactor design uses an unmoderated core running on [[fast neutron]]s, designed to allow any transuranic isotope to be consumed (and in some cases used as fuel). In addition to the benefits of removing the long [[half-life]] transuranics from the waste cycle, the SFR fuel expands when the reactor overheats, and the chain reaction automatically slows down. In this manner, it is passively safe.<ref>{{cite web |url=http://www.ne.anl.gov/About/hn/logos-winter02-psr.shtml|title=Passively safe reactors rely on nature to keep them cool|author=David Baurac}}</ref>

The SFR reactor concept is cooled by liquid [[sodium]] and fueled by a metallic alloy of uranium and [[plutonium]] or [[spent nuclear fuel]], the "nuclear waste" of [[light water reactor]]s. The SFR fuel is contained in steel cladding with liquid sodium filling in the space between the clad elements which make up the fuel assembly. One of the design challenges of an SFR is the risks of handling sodium, which reacts explosively if it comes into contact with water. However, the use of liquid metal instead of water as coolant allows the system to work at atmospheric pressure, reducing the risk of leakage.

The European Sustainable Nuclear Industrial Initiative is funding three Generation IV reactor systems, one of which is a sodium-cooled fast reactor, called ''[[ASTRID (reactor)|ASTRID]]'', Advanced Sodium Technical Reactor for Industrial Demonstration, [[Areva]], [[Commissariat à l'énergie atomique et aux énergies alternatives|CEA]] and [[Électricité de France|EDF]] are leading the design with British collaboration.<ref>{{cite web |url=http://www.power-eng.com/articles/2010/11/areva--cea-secure.html |title=Areva, CEA secure EUR650m funding to develop ASTRID sodium-cooled Generation IV reactor 11/11/2010}}</ref><ref>{{cite web |url=http://www.powermag.com/uk-and-france-sign-landmark-civil-nuclear-cooperation-agreement/ |title=UK and France Sign Landmark Civil Nuclear Cooperation Agreement 02/22/2012 . POWERnews}}</ref> Astrid will be rated about 600 MWe and is proposed to be built in France, near to the [[Phénix]] reactor. A final decision in construction is to be made in 2019<ref name="euronuclear.org"/>

The [[China|PRC]]'s first commercial-scale, 800 MWe, fast neutron reactor, to be situated near [[Sanming]] in [[Fujian province]] will be a SFR. In 2009 an agreement was signed that would entail the Russian [[BN-800 reactor]] design to be sold to the PRC once it is completed, this would be the first time commercial-scale fast neutron reactors have ever been exported.<ref>{{cite web |url=http://www.world-nuclear-news.org/C-Joint_venture_launched_for_Chinese_fast_reactor-3004104.html |title=Joint venture launched for Chinese fast reactor}}</ref> The BN-800 reactor became operational in 2014.

In India, the [[Prototype Fast Breeder Reactor]], a 500 MWe Sodium cooled fast reactor is being built at a cost of INR 5,677 crores (~US$900 million) and is expected to be commissioned by September 2016. The PFBR will be followed by six more Commercial Fast Breeder Reactors (CFBRs) of 500 MWe each.

The 400 MWe [[Fast Flux Test Facility]] operated successfully for ten years at the Hanford site in Washington State.

The 20 MWe [[EBR II]] operated successfully for over thirty years at the Idaho National Laboratory, until it was shut down in 1994.

==== Lead-cooled fast reactor (LFR) ====
[[File:Lead-Cooled Fast Reactor Schemata.svg|right|thumb|Lead-Cooled Fast Reactor (LFR)]]
{{Main article|Lead-cooled fast reactor}}
{{See also|MYRRHA}}
The '''lead-cooled fast reactor'''<ref name="Roadmap">{{cite journal| year=2002 | title=A Technology Roadmap for Generation IV Nuclear Energy Systems | last=US DOE Nuclear Energy Research Advisory Committee |volume=GIF-002-00|url=http://nuclear.energy.gov/genIV/documents/gen_iv_roadmap.pdf}}</ref> features a fast-neutron-spectrum [[lead]] or [[lead]]/[[bismuth]] [[eutectic]] ([[Lead-bismuth eutectic|LBE]]) liquid-metal-cooled reactor with a closed [[Nuclear fuel cycle|fuel cycle]]. Options include a range of plant ratings, including a "battery" of 50 to 150 MW of electricity that features a very long refueling interval, a modular system rated at 300 to 400 MW, and a large monolithic plant option at 1,200 MW. (The term ''battery'' refers to the long-life, factory-fabricated core, not to any provision for electrochemical energy conversion.) The fuel is metal or nitride-based containing [[Fertile material|fertile uranium]] and [[transuranic]]s. The LFR is cooled by natural [[convection]] with a reactor outlet coolant temperature of 550 °C, possibly ranging up to 800 °C with advanced materials. The higher temperature enables the production of [[Thermochemical cycle|hydrogen by thermochemical processes]].

The European Sustainable Nuclear Industrial Initiative is funding three Generation IV reactor systems, one of which is a lead-cooled fast reactor that is also an [[Subcritical reactor|accelerator-driven sub-critical]] reactor, called ''[[MYRRHA]]'', 100 MW(t), which will be built in [[Belgium]] with construction expected to begin after 2014 and the industrial scale version, known as ''Alfred'', slated to be constructed sometime after 2017. A reduced-power model of Myrrha called ''Guinevere'' was started up at [[Mol, Belgium|Mol]] in March 2009.<ref name="euronuclear.org"/> In 2012 the research team reported that Guinevere was operational.<ref>{{cite news|last1=Hellemans|first1=Alexander|title=Reactor-Accelerator Hybrid Achieves Successful Test Run|url=http://news.sciencemag.org/physics/2012/01/reactor-accelerator-hybrid-achieves-successful-test-run|accessdate=29 December 2014|work=Science Insider|date=12 January 2012}}</ref>

Two other lead-cooled fast reactors under development are the SVBR-100, a modular 100 MWe lead-bismuth cooled fast neutron reactor concept designed by OKB [[Gidropress]] in Russia and the BREST-OD-300 (Lead-cooled fast reactor) 300 MWe, to be developed after the SVBR-100, and built over 2016-20, it will dispense with the [[Uranium-238|fertile blanket]] around the core and will supersede the sodium cooled [[BN-600 reactor]] design, to purportedly give enhanced proliferation resistance.<ref name="powertecrussia.com"/>

== Advantages and disadvantages ==
Relative to current nuclear power plant technology, the claimed benefits for 4th generation reactors include:
* Nuclear waste that remains radioactive for a few centuries instead of millennia<ref>{{cite web |title=Strategies to Address Global Warming |url=http://www.columbia.edu/~jeh1/mailings/2009/20090713_Strategies.pdf}}</ref>
* 100-300 times more energy yield from the same amount of nuclear fuel<ref>{{cite web |title=4th Generation Nuclear Power |url=http://www.ossfoundation.us/projects/energy/nuclear}}</ref>
* Broader range of fuels, and even unencapsulated raw fuels (non-pebble [[Molten Salt Reactor|MSR]], [[LFTR]]).
* In some reactors, the ability to consume existing nuclear waste in the production of electricity, that is, a Closed [[nuclear fuel cycle]]. This strengthens the argument to deem [[nuclear power as renewable energy]].
* Improved operating safety features, such as (depending on design) avoidance of pressurized operation, automatic passive (unpowered, uncommanded) reactor shutdown, avoidance of water cooling and the associated risks of loss of water (leaks or boiling) and hydrogen generation/explosion and contamination of coolant water.

Nuclear reactors do not emit CO2 during operation, although like all [[low carbon power]] sources, the mining and construction phase can result in CO2 emissions, if energy sources which are not carbon neutral (such as fossil fuels), or CO2 emitting cements are used during the construction process.
A 2012 [[Yale University]] review published in the Journal of Industrial Ecology analyzing {{CO2}} [[life cycle assessment]] (LCA) emissions from [[nuclear power]] determined that:<ref name="Warner + Heath, JoIE">Warner, Ethan S.; Heath, Garvin A. [http://onlinelibrary.wiley.com/doi/10.1111/j.1530-9290.2012.00472.x/full Life Cycle Greenhouse Gas Emissions of Nuclear Electricity Generation: Systematic Review and Harmonization], ''Journal of Industrial Ecology'', [[Yale University]], published online April 17, 2012, doi: 10.1111/j.1530-9290.2012.00472.x.</ref>
{{Quote|''"The collective LCA literature indicates that life cycle [[Greenhouse gas|GHG]] [ greenhouse gas ] emissions from nuclear power are only a fraction of traditional fossil sources and comparable to renewable technologies."''}}
Although the paper primarily dealt with data from [[Generation II reactor]]s, and did not analyze the {{CO2}} emissions by 2050 of the presently under construction [[Generation III reactor]]s, it did summarize the Life Cycle Assessment findings of in development reactor technologies.''{{Quote|FBRs ''[ [[Fast Breeder Reactor]]s ]'' have been evaluated in the LCA literature. The limited literature that evaluates this potential future technology reports [[median]] life cycle GHG emissions... similar to or lower than LWRs[ Gen II [[light water reactor]]s ] and purports to consume little or no [[uranium market|uranium ore]].}}

A specific risk of the sodium-cooled fast reactor is related to using metallic sodium as a coolant. In case of a breach, sodium explosively reacts with water. Fixing breaches may also prove dangerous, as the cheapest noble gas [[argon]] is also used to prevent sodium oxidation. Argon, like helium, can displace oxygen in the air and can pose [[hypoxia (environmental)|hypoxia]] concerns, so workers may be exposed to this additional risk. This is a pertinent problem as can be testified by the events at the [[LMFBR|loop type]] [[Monju Nuclear Power Plant|Prototype Fast Breeder Reactor Monju]] at Tsuruga, Japan.<ref>{{cite news |title=Japan Strains to Fix a Reactor Damaged Before Quake |url=http://www.nytimes.com/2011/06/18/world/asia/18japan.html | work=The New York Times | first=Hiroko |last=Tabuchi |date=17 June 2011}}</ref>
Using lead or molten salts mitigates this problem by making the coolant less reactive and allowing a high freezing temperature and low pressure in case of a leak. Disadvantages of lead compared to sodium are much higher viscosity, much higher density, lower heat capacity, and more radioactive neutron activation products.

In many cases, there is already a large amount of experience built up with numerous proof of concept Gen IV designs. For example, the reactors at [[Fort St. Vrain Generating Station]] and [[HTR-10]] are similar to the proposed Gen IV [[VHTR]] designs, and the [[LMFBR|pool type]] [[EBR-II]], [[Phénix]] and [[BN-600]] reactor are similar to the proposed pool type Gen IV Sodium Cooled Fast reactors being designed.

== See also ==
{{colbegin|3}}
* [[Nuclear reactor]]
* [[Nuclear material]]
* [[Nuclear physics]]
* [[List of reactor types#Reactor types|List of reactor types]]
* [[Generation II reactor]]
* [[Generation III reactor]]
* [[Integral Fast Reactor]]
* [[Liquid fluoride thorium reactor]]
* [[Breeder reactor]]
* [[Small modular reactor]]
{{colend}}

==References==
{{Reflist|30em}}

== External links ==
* [https://inlportal.inl.gov/portal/server.pt?open=514&objID=1361&parentname=CommunityPage&parentid=10&mode=2&in_hi_userid=200&cached=true Article from Idaho National Laboratory detailing some current efforts at developing Gen. IV reactors.]
* [http://www.gen-4.org/ Generation IV International Forum (GIF)]
* [http://nuclear.energy.gov/genIV/neGenIV1.html U.S. Department of Energy Office of Nuclear Energy, Science and Technology]
* [http://www.engr.utk.edu/nuclear/colloquia/slides/Gen%20IV%20U-Tenn%20Presentation.pdf Gen IV presentation]
* [http://www.ecology.at/ecology/files/pr577_1.pdf Science or Fiction - Is there a Future for Nuclear?] (Nov. 2007) - A publication from the Austrian [[Ecology Institute (Austria)|Ecology Institute]] about 'Generation IV' and Fusion reactors.
* {{cite web |url=http://memagazine.asme.org/Articles/2011/December/Nuclear_Power_After_Fukushima.cfm |title=Nuclear Power After Fukushima |author=Gail H. Marcus |date=December 2011 |work=Mechanical Engineering (the magazine of [[ASME]]) |accessdate=23 January 2012}} "In the wake of a severe plant accident, advanced reactor designs are getting renewed attention."
* [http://www.itheo.org/ International Thorium Energy Organisation - www.IThEO.org]
* [http://www.ithec.org/ International Thorium Energy Committee - iThEC]

{{Nuclear fission reactors}}

[[Category:Nuclear power reactor types]]
[[Category:Idaho National Laboratory]]

Benutzer:Snackroeg/Kernreaktoren der Generation 5

2016-10-20T02:50:27Z

Boundarylayer: /* Molten-salt reactor (MSR) */

[[File:GenIVRoadmap-en.svg|thumb|480px|Nuclear Energy Systems Deployable no later than 2030 and offering significant advances in sustainability, safety and reliability, and economics]]

'''Generation IV reactors''' ('''Gen IV''') are a set of [[nuclear reactor]] designs currently being researched for commercial applications by the Generation IV International Forum, with [[Technology readiness level]]s varying between the level requiring a demonstration, to economical competitive implementation. They are motivated by a variety of goals including improved safety, sustainability, efficiency, and cost.

Most of these designs are generally not expected to be available for commercial construction before 2030–40.<ref name="Generation IV">[http://www.world-nuclear.org/info/Nuclear-Fuel-Cycle/Power-Reactors/Generation-IV-Nuclear-Reactors/]</ref> Presently the majority of reactors in operation around the world are considered [[Generation II reactor|second generation reactor]] systems, as the vast majority of the [[Generation I reactor|first-generation]] systems were retired some time ago, and there are only a dozen or so [[Generation III reactor]]s in operation (2014). [[Nuclear reactor#Generation V+ reactors|Generation V reactors]] refer to reactors that are purely theoretical and are therefore not yet considered feasible in the short term, resulting in limited [[R&D]] funding.

== History ==
The Generation IV International Forum (GIF) is "a co-operative international endeavour which was set up to carry out the research and development needed to establish the feasibility and performance capabilities of the next generation nuclear energy systems."<ref>{{Cite web|url=https://www.gen-4.org/gif/jcms/c_9260/public|title=GIF Portal - Home - Public|website=www.gen-4.org|access-date=2016-07-25}}</ref> It was founded in 2001. There are currently ten active members of the Generation IV International Forum (GIF): [[Canada]], [[China]], the [[European Atomic Energy Community]] (Euratom), [[France]], [[Japan]], [[Russia]], [[South Africa]], [[South Korea]], [[Switzerland]], and the [[United States]]. The non-active members are [[Argentina]], [[Brazil]], and the [[United Kingdom]].<ref name="gen-4">{{cite web|url=https://www.gen-4.org/gif/jcms/c_9492/members|title=GIF Membership|website=gen-4.org|accessdate=28 October 2014}}</ref> Switzerland joined in 2002, Euratom in 2003, and China and Russia in 2006. The remaining countries (excluding Australia) were founding members.<ref name="gen-4" />

The 36th GIF meeting in [[Brussels]] was held in November 2013.<ref>{{cite web|url=http://www.energy.gov/ne/articles/generation-iv-international-forum-updates-technology-roadmap-and-builds-future|title=generation IV international forum updates technology roadmap and builds future. DOE}}</ref><ref>{{cite web|url=http://events.r20.constantcontact.com/register/event?llr=mscrkjkab&oeidk=a07e7melf609716b2c6|title=The Generation IV international forum holds their 36th meeting on Monday 18th Nov 2013 in Brussels.}}</ref> The ''Technology Roadmap Update for Generation IV Nuclear Energy Systems'' was published in January 2014 which details R&D objectives for the next decade.<ref>[https://web.archive.org/web/20140625102915/https://www.gen-4.org/gif/upload/docs/application/pdf/2014-03/gif-tru2014.pdf Technology Roadmap Update for Generation IV Nuclear Energy Systems]</ref> A breakdown of the reactor designs being researched by each forum member has been made available.<ref>[https://web.archive.org/web/20140708023538/https://www.gen-4.org/gif/upload/docs/application/pdf/2014-03/gif_overview_presentation_v9_final3_web.pdf Generation IV International Forum, overview, John E. Kelly, page 15]</ref>

[[Nuclear power in Australia|Australia]] joined the forum in 2016.<ref>http://archive.is/22e5F</ref>

== Reactor types ==
Many reactor types were considered initially; however, the list was downsized to focus on the most promising technologies and those that could most likely meet the goals of the Gen IV initiative.<ref name="Generation IV"/> Three systems are nominally [[thermal reactor]]s and three are [[fast reactor]]s. The Very High Temperature Reactor (VHTR) is also being researched for potentially providing high quality process heat for [[thermochemical cycle|hydrogen production]]. The fast reactors offer the possibility of burning [[actinides]] to further reduce waste and of being able to "[[breeder reactor|breed more fuel]]" than they consume. These systems offer significant advances in sustainability, safety and reliability, economics, proliferation resistance (depending on perspective) and physical protection.

{| class=wikitable
|-
! System
! Neutron Spectrum
! Coolant
! Temperature (°C)
! Fuel Cycle
! Size (MW)
!Example developers
|-
| [[Very high temperature reactor|VHTR]]
| Thermal
| Helium
| 900–1000
| Open
| 250–300
|[[Japan Atomic Energy Agency|JAEA]] ([[HTTR]]), [[Tsinghua University]] ([[HTR-10]]), X-energy<ref name="energy.gov">{{cite web|title=Energy Department Announces New Investments in Advanced Nuclear Power Reactors...|url=http://www.energy.gov/articles/energy-department-announces-new-investments-advanced-nuclear-power-reactors-help-meet|website=[[United States Department of Energy|US Department of Energy]]|accessdate=16 January 2016}}</ref>
|-
| [[Sodium-cooled fast reactor|SFR]]
| Fast
| Sodium
| 550
| Closed
| 30–150, 300–1500, 1000–2000
|[[TerraPower]] ([[Traveling wave reactor|TWR]]), Toshiba ([[Toshiba 4S|4S]]), [[GE Hitachi Nuclear Energy]] ([[PRISM (reactor)|PRISM]])
|-
| [[Supercritical water reactor|SCWR]]
| Thermal/fast
| Water
| 510–625
| Open/closed
| 300–700, 1000–1500
|
|-
| [[Gas-cooled fast reactor|GFR]]
| Fast
| Helium
| 850
| Closed
| 1200
|
|-
| [[Lead-cooled fast reactor|LFR]]
| Fast
| Lead
| 480–800
| Closed
| 20–180, 300–1200, 600–1000
|
|-
| [[Molten salt reactor|MSR]]
| Fast/thermal
| Fluoride salts
| 700–800
| Closed
| 250, 1000
|[[Flibe Energy]] ([[Liquid fluoride thorium reactor|LFTR]]), [[Transatomic Power]], Thorium Tech Solution ([[Fuji Molten Salt Reactor|FUJI MSR]]), Terrestrial Energy ([[IMSR]]), [[Southern Company Services|Southern Company]]<ref name="energy.gov"/>
|}
<ref>https://www.gen-4.org/gif/upload/docs/application/pdf/2013-09/gif_rd_outlook_for_generation_iv_nuclear_energy_systems.pdf</ref>

=== Thermal reactors ===
A [[Thermal-neutron reactor|thermal reactor]] is a [[nuclear reactor]] that uses slow or [[thermal neutrons]]. A [[neutron moderator]] is used to slow the [[neutron]]s emitted by fission to make them more likely to be captured by the fuel.

==== Very-high-temperature reactor (VHTR) ====
[[File:Very High Temperature Reactor.svg|right|thumb|Very-High-Temperature Reactor (VHTR)]]
{{Main article|Very high temperature reactor}}
{{see also|Fort St. Vrain Generating Station|HTTR|HTR-10}}
The '''very high temperature reactor''' concept uses a [[graphite]]-moderated core with a once-through [[uranium]] fuel cycle, using helium or molten salt as the [[Very high temperature reactor#Coolant|coolant]]. This reactor design envisions an outlet temperature of 1,000 °C. The reactor core can be either a prismatic-block or a [[pebble bed reactor]] design. The high temperatures enable applications such as process heat or [[hydrogen]] production via the thermochemical [[Sulfur-iodine cycle|iodine-sulfur]] process. It would also be [[Passive nuclear safety|passively safe]].

The planned construction of the first VHTR, the South African PBMR ([[pebble bed modular reactor]]), lost government funding in February, 2010.<ref>[http://www.powergenworldwide.com/index/display/articledisplay/6322207443/articles/power-engineering-international/volume-18/Issue_3/regulars/world-news/INTERNATIONAL.html South Africa to stop funding Pebble Bed nuclear reactor]</ref> A pronounced increase of costs and concerns about possible unexpected technical problems had discouraged potential investors and customers.

The [[Peoples Republic of China]] began construction of a 200-MW High Temperature Pebble bed reactor in 2012 as a successor to its [[HTR-10]].<ref>[http://www.nucnet.org/all-the-news/2013/01/07/china-begins-construction-of-first-generation-iv-htr-pm-unit Nucnet Report: 'China Begins Construction of First Generation IV HTR-PM Unit', 7 January 2013]</ref>

Also in 2012, as part of the [[Next Generation Nuclear Plant]] competition, [[Idaho National Laboratory]] approved a design similar to [[Areva]]'s prismatic block [http://us.areva.com/EN/home-3225/areva-inc-areva-htgr.html Antares reactor] as the chosen [[HTGR]] to be deployed as a prototype by 2021. It was in competition with [[General Atomics]]' [[Gas turbine modular helium reactor]] and [[Westinghouse Electric Company|Westinghouse]]'s [[Pebble Bed Modular Reactor]].<ref name="World nuclear news">{{cite web|url=http://www.world-nuclear-news.org/NN-Areva_modular_reactor_selected_for_NGNP_development-1502124.html|title=INL approves Antares design}}</ref>

==== Molten-salt reactor (MSR) ====
[[File:Molten Salt Reactor.svg|right|thumb|Molten Salt Reactor (MSR)]]
{{Main article|Molten salt reactor}}
{{see also|Liquid fluoride thorium reactor}}
A '''molten salt reactor'''<ref name="Roadmap"/> is a type of [[nuclear reactor]] where the primary [[coolant]], or even the fuel itself is a molten salt mixture. There have been many designs put forward for this type of reactor and a few prototypes built. The early concepts and many current ones rely on [[nuclear fuel]] dissolved in the molten [[fluoride]] salt as [[uranium tetrafluoride]] (UF4) or [[thorium tetrafluoride]] (ThF4). The fluid would reach [[Nuclear reactor physics#Criticality|criticality]] by flowing into a [[graphite]] core which would also serve as the [[neutron moderator|moderator]]. Many current concepts rely on fuel that is dispersed in a graphite matrix with the molten salt providing low pressure, high temperature cooling.

The Gen IV MSR is more accurately termed an [[epithermal neutron|epithermal reactor]] than a thermal reactor due to the average speed of the neutrons that would cause the fission events within its fuel being faster than [[thermal neutron]]s.<ref>{{cite web |url=https://inlportal.inl.gov/portal/server.pt?open=514&objID=1361&parentname=CommunityPage&parentid=10&mode=2&in_hi_userid=200&cached=true |title=Idaho National Laboratory detailing some current efforts at developing Gen. IV reactors}}</ref>

The principle of a MSR can be used for thermal, epithermal and fast reactors. Since 2005 the focus has moved towards a fast spectrum MSR (MSFR).<ref>H. Boussier, S. Delpech, V. Ghetta et Al. : The Molten Salt Reactor (MSR) in Generation IV: Overview and Perspectives, GIF SYMPOSIUM PROCEEDINGS/2012 ANNUAL REPORT, NEA No. 7141, pp95 [https://www.gen-4.org/gif/jcms/c_44720/annual-reports]
</ref>

While most MSR designs being pursued are largely derived from the 1960s [[Molten-Salt Reactor Experiment]](MSRE), variants of molten salt technology include the conceptual ''[[Dual fluid reactor]]'' which is being designed with lead as a cooling medium but molten salt fuel, commonly as the metal chloride e.g [[Plutonium(III) chloride]], to aid in greater "nuclear waste" closed-fuel cycle capabilities.
Other notable approaches differing substantially from those with MSRE [[pedigree]] include the ''Stable Salt Reactor''(SSR) concept promoted by MOLTEX, which encases the molten salt in hundreds of the common solid [[fuel rod]]s that are already well established in the nuclear industry. This latter British design was found to be the most competitive for [[Small modular reactor]] development by a British based consultancy firm ''Energy Process Development'' in 2015.<ref>[http://www.daretothink.org/europe-moltex-stable-salt-reactor/ Europe: Moltex’ Stable Salt Reactor]</ref><ref>[http://analysis.nuclearenergyinsider.com/moltex-energy-sees-uk-canada-smr-licensing-springboard-asia Moltex Energy sees UK, Canada SMR licensing as springboard to Asia Jun 28, 2016]</ref>

==== Supercritical-water-cooled reactor (SCWR) ====
[[File:Supercritical-Water-Cooled Reactor.svg|right|thumb|Supercritical-Water-Cooled Reactor (SCWR)]]
{{Main article|Supercritical water reactor}}
The '''supercritical water reactor''' (SCWR)<ref name="Roadmap"/> is a [[reduced moderation water reactor]] concept that, due to the average speed of the neutrons that would cause the fission events within the fuel being faster than [[thermal neutron]]s, it is more accurately termed an [[epithermal neutron|epithermal reactor]] than a thermal reactor. It uses [[supercritical fluid|supercritical water]] as the working fluid. SCWRs are basically [[light water reactor]]s (LWR) operating at higher pressure and temperatures with a direct, once-through heat exchange cycle. As most commonly envisioned, it would operate on a direct cycle, much like a boiling water reactor ([[BWR]]), but since it uses supercritical water (not to be confused with [[Critical mass (nuclear)|critical mass]]) as the working fluid, it would have only one water phase present, which makes the supercritical heat exchange method more similar to a pressurized water reactor ([[Pressurized water reactor|PWR]]). It could operate at much higher temperatures than both current PWRs and BWRs.

Supercritical water-cooled reactors (SCWRs) are promising advanced nuclear systems because of their high [[thermal efficiency]] (i.e., about 45% vs. about 33% efficiency for current LWRs) and considerable plant simplification.

The main mission of the SCWR is generation of low-cost [[electricity]]. It is built upon two proven technologies, LWRs, which are the most commonly deployed power generating reactors in the world, and superheated [[fossil fuel]] fired [[boiler]]s, a large number of which are also in use around the world. The SCWR concept is being investigated by 32 organizations in 13 countries.{{citation needed|date=October 2012}}

A SCWR Design under development is the [[VVER]]-1700/393 (VVER-SCWR or VVER-SKD) — a Russian Supercritical-water-cooled reactor with double-inlet-core and a [[breeder reactor|breeding ratio]] of 0.95.<ref name="powertecrussia.com">{{cite web |url=http://www.powertecrussia.com/blog/tag/nuclear-power/ |title=Technology Developments & Plant Efficiency for the Russian Nuclear Power Generation Market Wednesday |date=March 24, 2010}}</ref>

=== Fast reactors ===
A [[Fast-neutron reactor|fast reactor]] directly uses the fast neutrons emitted by fission, without moderation. Unlike thermal neutron reactors, fast neutron reactors can be configured to "'''burn'''", or fission, all [[actinides]], and given enough time, therefore drastically reduce the actinides fraction in [[spent nuclear fuel]] produced by the present world fleet of thermal neutron [[light water reactor]]s, thus closing the [[nuclear fuel cycle]]. Alternatively, if configured differently, they can also [[breeder reactor|'''breed''']] more actinide fuel than they consume.

==== Gas-cooled fast reactor (GFR) ====
[[File:Gas-Cooled Fast Reactor Schemata.svg|right|thumb|Gas-Cooled Fast Reactor (GFR)]]
{{Main article|Gas-cooled fast reactor}}
The '''gas-cooled fast reactor''' (GFR)<ref name="Roadmap"/> system features a fast-neutron spectrum and closed fuel cycle for efficient conversion of [[Fertile material|fertile uranium]] and management of actinides. The reactor is [[helium]]-cooled and with an outlet temperature of 850 °C it is an evolution of the [[very-high-temperature reactor]] (VHTR) to a more sustainable fuel cycle. It will use a direct [[Brayton cycle]] [[Closed-cycle gas turbine|gas turbine]] for high thermal efficiency. Several fuel forms are being considered for their potential to operate at very high temperatures and to ensure an excellent retention of [[Nuclear fission|fission]] products: composite [[ceramic]] fuel, advanced fuel particles, or ceramic clad elements of actinide compounds. Core configurations are being considered based on pin- or plate-based fuel assemblies or prismatic blocks.

The European Sustainable Nuclear Industrial Initiative is funding three Generation IV reactor systems, one of which is a gas-cooled fast reactor, called ''Allegro'', 100 MW(t), which will be built in a central or eastern European country with construction expected to begin in 2018.<ref name="euronuclear.org">{{cite web |url=https://www.euronuclear.org/1-information/news/Gen-IV.htm |title=The European Sustainable Nuclear Industrial Initiative (ESNII) will support three Generation IV reactor systems: a sodium-cooled fast reactor, or SFR, called ''Astrid'' that is proposed by France; a gas-cooled fast reactor, GFR, called ''Allegro'' supported by central and eastern Europe; and a lead-cooled fast reactor, LFR, technology pilot called ''Myrrha'' that is proposed by Belgium.}}</ref> The central European [[Visegrád Group]] are committed to pursuing the technology.<ref>{{cite web |url=http://www.alphagalileo.org/ViewItem.aspx?ItemId=133111&CultureCode=en |title=The V4G4 Centre of Excellence for performing joint research, development and innovation in the field of Generation-4 (G4) nuclear reactors have been established. 20 July 2013 National Center for Nuclear Research (NCBJ]}}</ref> In 2013 German, British, and French institutes finished a 3-year collaboration study on the follow on industrial scale design, known as ''GoFastR''.<ref>{{cite web |url=http://www.ist-world.org/ProjectDetails.aspx?ProjectId=5cb8f3f283574cc6b2bdbf72533172d8 |title=the European Gas cooled Fast Reactor.}}</ref> They were funded by the EU's 7th FWP [[framework programme]], with the goal of making a sustainable VHTR.<ref>{{cite web |url=http://www.2020-horizon.com/GOFASTR-European-Gas-Cooled-Fast-Reactor%28GOFASTR%29-s312.html |title=The GOFASTR research program}}</ref>

==== Sodium-cooled fast reactor (SFR) ====
[[File:Sodium-Cooled Fast Reactor Schemata.svg|right|thumb|Pool design Sodium-Cooled Fast Reactor (SFR)]]
{{Main article|Sodium-cooled fast reactor}}
{{see also|Experimental Breeder Reactor II|S-PRISM|BN-800 reactor|Toshiba 4S}}
The SFR<ref name="Roadmap"/> is a project that builds on two closely related existing projects, the liquid metal [[Breeder reactor#Fast breeder reactor|fast breeder reactor]] and the [[integral fast reactor]].

The goals are to increase the efficiency of uranium usage by [[breeder reactor|breeding]] plutonium and eliminating the need for [[transuranic]] isotopes ever to leave the site. The reactor design uses an unmoderated core running on [[fast neutron]]s, designed to allow any transuranic isotope to be consumed (and in some cases used as fuel). In addition to the benefits of removing the long [[half-life]] transuranics from the waste cycle, the SFR fuel expands when the reactor overheats, and the chain reaction automatically slows down. In this manner, it is passively safe.<ref>{{cite web |url=http://www.ne.anl.gov/About/hn/logos-winter02-psr.shtml|title=Passively safe reactors rely on nature to keep them cool|author=David Baurac}}</ref>

The SFR reactor concept is cooled by liquid [[sodium]] and fueled by a metallic alloy of uranium and [[plutonium]] or [[spent nuclear fuel]], the "nuclear waste" of [[light water reactor]]s. The SFR fuel is contained in steel cladding with liquid sodium filling in the space between the clad elements which make up the fuel assembly. One of the design challenges of an SFR is the risks of handling sodium, which reacts explosively if it comes into contact with water. However, the use of liquid metal instead of water as coolant allows the system to work at atmospheric pressure, reducing the risk of leakage.

The European Sustainable Nuclear Industrial Initiative is funding three Generation IV reactor systems, one of which is a sodium-cooled fast reactor, called ''[[ASTRID (reactor)|ASTRID]]'', Advanced Sodium Technical Reactor for Industrial Demonstration, [[Areva]], [[Commissariat à l'énergie atomique et aux énergies alternatives|CEA]] and [[Électricité de France|EDF]] are leading the design with British collaboration.<ref>{{cite web |url=http://www.power-eng.com/articles/2010/11/areva--cea-secure.html |title=Areva, CEA secure EUR650m funding to develop ASTRID sodium-cooled Generation IV reactor 11/11/2010}}</ref><ref>{{cite web |url=http://www.powermag.com/uk-and-france-sign-landmark-civil-nuclear-cooperation-agreement/ |title=UK and France Sign Landmark Civil Nuclear Cooperation Agreement 02/22/2012 . POWERnews}}</ref> Astrid will be rated about 600 MWe and is proposed to be built in France, near to the [[Phénix]] reactor. A final decision in construction is to be made in 2019<ref name="euronuclear.org"/>

The [[China|PRC]]'s first commercial-scale, 800 MWe, fast neutron reactor, to be situated near [[Sanming]] in [[Fujian province]] will be a SFR. In 2009 an agreement was signed that would entail the Russian [[BN-800 reactor]] design to be sold to the PRC once it is completed, this would be the first time commercial-scale fast neutron reactors have ever been exported.<ref>{{cite web |url=http://www.world-nuclear-news.org/C-Joint_venture_launched_for_Chinese_fast_reactor-3004104.html |title=Joint venture launched for Chinese fast reactor}}</ref> The BN-800 reactor became operational in 2014.

In India, the [[Prototype Fast Breeder Reactor]], a 500 MWe Sodium cooled fast reactor is being built at a cost of INR 5,677 crores (~US$900 million) and is expected to be commissioned by September 2016. The PFBR will be followed by six more Commercial Fast Breeder Reactors (CFBRs) of 500 MWe each.

The 400 MWe [[Fast Flux Test Facility]] operated successfully for ten years at the Hanford site in Washington State.

The 20 MWe [[EBR II]] operated successfully for over thirty years at the Idaho National Laboratory, until it was shut down in 1994.

==== Lead-cooled fast reactor (LFR) ====
[[File:Lead-Cooled Fast Reactor Schemata.svg|right|thumb|Lead-Cooled Fast Reactor (LFR)]]
{{Main article|Lead-cooled fast reactor}}
{{See also|MYRRHA}}
The '''lead-cooled fast reactor'''<ref name="Roadmap">{{cite journal| year=2002 | title=A Technology Roadmap for Generation IV Nuclear Energy Systems | last=US DOE Nuclear Energy Research Advisory Committee |volume=GIF-002-00|url=http://nuclear.energy.gov/genIV/documents/gen_iv_roadmap.pdf}}</ref> features a fast-neutron-spectrum [[lead]] or [[lead]]/[[bismuth]] [[eutectic]] ([[Lead-bismuth eutectic|LBE]]) liquid-metal-cooled reactor with a closed [[Nuclear fuel cycle|fuel cycle]]. Options include a range of plant ratings, including a "battery" of 50 to 150 MW of electricity that features a very long refueling interval, a modular system rated at 300 to 400 MW, and a large monolithic plant option at 1,200 MW. (The term ''battery'' refers to the long-life, factory-fabricated core, not to any provision for electrochemical energy conversion.) The fuel is metal or nitride-based containing [[Fertile material|fertile uranium]] and [[transuranic]]s. The LFR is cooled by natural [[convection]] with a reactor outlet coolant temperature of 550 °C, possibly ranging up to 800 °C with advanced materials. The higher temperature enables the production of [[Thermochemical cycle|hydrogen by thermochemical processes]].

The European Sustainable Nuclear Industrial Initiative is funding three Generation IV reactor systems, one of which is a lead-cooled fast reactor that is also an [[Subcritical reactor|accelerator-driven sub-critical]] reactor, called ''[[MYRRHA]]'', 100 MW(t), which will be built in [[Belgium]] with construction expected to begin after 2014 and the industrial scale version, known as ''Alfred'', slated to be constructed sometime after 2017. A reduced-power model of Myrrha called ''Guinevere'' was started up at [[Mol, Belgium|Mol]] in March 2009.<ref name="euronuclear.org"/> In 2012 the research team reported that Guinevere was operational.<ref>{{cite news|last1=Hellemans|first1=Alexander|title=Reactor-Accelerator Hybrid Achieves Successful Test Run|url=http://news.sciencemag.org/physics/2012/01/reactor-accelerator-hybrid-achieves-successful-test-run|accessdate=29 December 2014|work=Science Insider|date=12 January 2012}}</ref>

Two other lead-cooled fast reactors under development are the SVBR-100, a modular 100 MWe lead-bismuth cooled fast neutron reactor concept designed by OKB [[Gidropress]] in Russia and the BREST-OD-300 (Lead-cooled fast reactor) 300 MWe, to be developed after the SVBR-100, and built over 2016-20, it will dispense with the [[Uranium-238|fertile blanket]] around the core and will supersede the sodium cooled [[BN-600 reactor]] design, to purportedly give enhanced proliferation resistance.<ref name="powertecrussia.com"/>

== Advantages and disadvantages ==
Relative to current nuclear power plant technology, the claimed benefits for 4th generation reactors include:
* Nuclear waste that remains radioactive for a few centuries instead of millennia<ref>{{cite web |title=Strategies to Address Global Warming |url=http://www.columbia.edu/~jeh1/mailings/2009/20090713_Strategies.pdf}}</ref>
* 100-300 times more energy yield from the same amount of nuclear fuel<ref>{{cite web |title=4th Generation Nuclear Power |url=http://www.ossfoundation.us/projects/energy/nuclear}}</ref>
* Broader range of fuels, and even unencapsulated raw fuels (non-pebble [[Molten Salt Reactor|MSR]], [[LFTR]]).
* In some reactors, the ability to consume existing nuclear waste in the production of electricity, that is, a Closed [[nuclear fuel cycle]]. This strengthens the argument to deem [[nuclear power as renewable energy]].
* Improved operating safety features, such as (depending on design) avoidance of pressurized operation, automatic passive (unpowered, uncommanded) reactor shutdown, avoidance of water cooling and the associated risks of loss of water (leaks or boiling) and hydrogen generation/explosion and contamination of coolant water.

Nuclear reactors do not emit CO2 during operation, although like all [[low carbon power]] sources, the mining and construction phase can result in CO2 emissions, if energy sources which are not carbon neutral (such as fossil fuels), or CO2 emitting cements are used during the construction process.
A 2012 [[Yale University]] review published in the Journal of Industrial Ecology analyzing {{CO2}} [[life cycle assessment]] (LCA) emissions from [[nuclear power]] determined that:<ref name="Warner + Heath, JoIE">Warner, Ethan S.; Heath, Garvin A. [http://onlinelibrary.wiley.com/doi/10.1111/j.1530-9290.2012.00472.x/full Life Cycle Greenhouse Gas Emissions of Nuclear Electricity Generation: Systematic Review and Harmonization], ''Journal of Industrial Ecology'', [[Yale University]], published online April 17, 2012, doi: 10.1111/j.1530-9290.2012.00472.x.</ref>
{{Quote|''"The collective LCA literature indicates that life cycle [[Greenhouse gas|GHG]] [ greenhouse gas ] emissions from nuclear power are only a fraction of traditional fossil sources and comparable to renewable technologies."''}}
Although the paper primarily dealt with data from [[Generation II reactor]]s, and did not analyze the {{CO2}} emissions by 2050 of the presently under construction [[Generation III reactor]]s, it did summarize the Life Cycle Assessment findings of in development reactor technologies.''{{Quote|FBRs ''[ [[Fast Breeder Reactor]]s ]'' have been evaluated in the LCA literature. The limited literature that evaluates this potential future technology reports [[median]] life cycle GHG emissions... similar to or lower than LWRs[ Gen II [[light water reactor]]s ] and purports to consume little or no [[uranium market|uranium ore]].}}

A specific risk of the sodium-cooled fast reactor is related to using metallic sodium as a coolant. In case of a breach, sodium explosively reacts with water. Fixing breaches may also prove dangerous, as the cheapest noble gas [[argon]] is also used to prevent sodium oxidation. Argon, like helium, can displace oxygen in the air and can pose [[hypoxia (environmental)|hypoxia]] concerns, so workers may be exposed to this additional risk. This is a pertinent problem as can be testified by the events at the [[LMFBR|loop type]] [[Monju Nuclear Power Plant|Prototype Fast Breeder Reactor Monju]] at Tsuruga, Japan.<ref>{{cite news |title=Japan Strains to Fix a Reactor Damaged Before Quake |url=http://www.nytimes.com/2011/06/18/world/asia/18japan.html | work=The New York Times | first=Hiroko |last=Tabuchi |date=17 June 2011}}</ref>
Using lead or molten salts mitigates this problem by making the coolant less reactive and allowing a high freezing temperature and low pressure in case of a leak. Disadvantages of lead compared to sodium are much higher viscosity, much higher density, lower heat capacity, and more radioactive neutron activation products.

In many cases, there is already a large amount of experience built up with numerous proof of concept Gen IV designs. For example, the reactors at [[Fort St. Vrain Generating Station]] and [[HTR-10]] are similar to the proposed Gen IV [[VHTR]] designs, and the [[LMFBR|pool type]] [[EBR-II]], [[Phénix]] and [[BN-600]] reactor are similar to the proposed pool type Gen IV Sodium Cooled Fast reactors being designed.

== See also ==
{{colbegin|3}}
* [[Nuclear reactor]]
* [[Nuclear material]]
* [[Nuclear physics]]
* [[List of reactor types#Reactor types|List of reactor types]]
* [[Generation II reactor]]
* [[Generation III reactor]]
* [[Integral Fast Reactor]]
* [[Liquid fluoride thorium reactor]]
* [[Breeder reactor]]
* [[Small modular reactor]]
{{colend}}

==References==
{{Reflist|30em}}

== External links ==
* [https://inlportal.inl.gov/portal/server.pt?open=514&objID=1361&parentname=CommunityPage&parentid=10&mode=2&in_hi_userid=200&cached=true Article from Idaho National Laboratory detailing some current efforts at developing Gen. IV reactors.]
* [http://www.gen-4.org/ Generation IV International Forum (GIF)]
* [http://nuclear.energy.gov/genIV/neGenIV1.html U.S. Department of Energy Office of Nuclear Energy, Science and Technology]
* [http://www.engr.utk.edu/nuclear/colloquia/slides/Gen%20IV%20U-Tenn%20Presentation.pdf Gen IV presentation]
* [http://www.ecology.at/ecology/files/pr577_1.pdf Science or Fiction - Is there a Future for Nuclear?] (Nov. 2007) - A publication from the Austrian [[Ecology Institute (Austria)|Ecology Institute]] about 'Generation IV' and Fusion reactors.
* {{cite web |url=http://memagazine.asme.org/Articles/2011/December/Nuclear_Power_After_Fukushima.cfm |title=Nuclear Power After Fukushima |author=Gail H. Marcus |date=December 2011 |work=Mechanical Engineering (the magazine of [[ASME]]) |accessdate=23 January 2012}} "In the wake of a severe plant accident, advanced reactor designs are getting renewed attention."
* [http://www.itheo.org/ International Thorium Energy Organisation - www.IThEO.org]
* [http://www.ithec.org/ International Thorium Energy Committee - iThEC]

{{Nuclear fission reactors}}

[[Category:Nuclear power reactor types]]
[[Category:Idaho National Laboratory]]

Benutzer:Snackroeg/Kernreaktoren der Generation 5

2016-10-13T23:55:26Z

Boundarylayer: /* Molten-salt reactor (MSR) */ DFR and SSR added as notable

[[File:GenIVRoadmap-en.svg|thumb|480px|Nuclear Energy Systems Deployable no later than 2030 and offering significant advances in sustainability, safety and reliability, and economics]]

'''Generation IV reactors''' ('''Gen IV''') are a set of [[nuclear reactor]] designs currently being researched for commercial applications by the Generation IV International Forum, with [[Technology readiness level]]s varying between the level requiring a demonstration, to economical competitive implementation. They are motivated by a variety of goals including improved safety, sustainability, efficiency, and cost.

Most of these designs, with the exception of the [[BN-1200 reactor]], are generally not expected to be available for commercial construction before 2030–40.<ref name="Generation IV">[http://www.world-nuclear.org/info/Nuclear-Fuel-Cycle/Power-Reactors/Generation-IV-Nuclear-Reactors/]</ref> Presently the majority of reactors in operation around the world are considered [[Generation II reactor|second generation reactor]] systems, as the vast majority of the [[Generation I reactor|first-generation]] systems were retired some time ago, and there are only a dozen or so [[Generation III reactor]]s in operation (2014). [[Nuclear reactor#Generation V+ reactors|Generation V reactors]] refer to reactors that are purely theoretical and are therefore not yet considered feasible in the short term, resulting in limited [[R&D]] funding.

== History ==
The Generation IV International Forum (GIF) is "a co-operative international endeavour which was set up to carry out the research and development needed to establish the feasibility and performance capabilities of the next generation nuclear energy systems."<ref>{{Cite web|url=https://www.gen-4.org/gif/jcms/c_9260/public|title=GIF Portal - Home - Public|website=www.gen-4.org|access-date=2016-07-25}}</ref> It was founded in 2001. There are currently ten active members of the Generation IV International Forum (GIF): [[Canada]], [[China]], the [[European Atomic Energy Community]] (Euratom), [[France]], [[Japan]], [[Russia]], [[South Africa]], [[South Korea]], [[Switzerland]], and the [[United States]]. The non-active members are [[Argentina]], [[Brazil]], and the [[United Kingdom]].<ref name="gen-4">{{cite web|url=https://www.gen-4.org/gif/jcms/c_9492/members|title=GIF Membership|website=gen-4.org|accessdate=28 October 2014}}</ref> Switzerland joined in 2002, Euratom in 2003, and China and Russia in 2006. The remaining countries (excluding Australia) were founding members.<ref name="gen-4" />

The 36th GIF meeting in [[Brussels]] was held in November 2013.<ref>{{cite web|url=http://www.energy.gov/ne/articles/generation-iv-international-forum-updates-technology-roadmap-and-builds-future|title=generation IV international forum updates technology roadmap and builds future. DOE}}</ref><ref>{{cite web|url=http://events.r20.constantcontact.com/register/event?llr=mscrkjkab&oeidk=a07e7melf609716b2c6|title=The Generation IV international forum holds their 36th meeting on Monday 18th Nov 2013 in Brussels.}}</ref> The ''Technology Roadmap Update for Generation IV Nuclear Energy Systems'' was published in January 2014 which details R&D objectives for the next decade.<ref>[https://web.archive.org/web/20140625102915/https://www.gen-4.org/gif/upload/docs/application/pdf/2014-03/gif-tru2014.pdf Technology Roadmap Update for Generation IV Nuclear Energy Systems]</ref> A breakdown of the reactor designs being researched by each forum member has been made available.<ref>[https://web.archive.org/web/20140708023538/https://www.gen-4.org/gif/upload/docs/application/pdf/2014-03/gif_overview_presentation_v9_final3_web.pdf Generation IV International Forum, overview, John E. Kelly, page 15]</ref>

[[Nuclear power in Australia|Australia]] joined the forum in 2016.<ref>http://archive.is/22e5F</ref>

== Reactor types ==
Many reactor types were considered initially; however, the list was downsized to focus on the most promising technologies and those that could most likely meet the goals of the Gen IV initiative.<ref name="Generation IV"/> Three systems are nominally [[thermal reactor]]s and three are [[fast reactor]]s. The Very High Temperature Reactor (VHTR) is also being researched for potentially providing high quality process heat for [[thermochemical cycle|hydrogen production]]. The fast reactors offer the possibility of burning [[actinides]] to further reduce waste and of being able to "[[breeder reactor|breed more fuel]]" than they consume. These systems offer significant advances in sustainability, safety and reliability, economics, proliferation resistance (depending on perspective) and physical protection.

{| class=wikitable
|-
! System
! Neutron Spectrum
! Coolant
! Temperature (°C)
! Fuel Cycle
! Size (MW)
!Example developers
|-
| [[Very high temperature reactor|VHTR]]
| Thermal
| Helium
| 900–1000
| Open
| 250–300
|[[Japan Atomic Energy Agency|JAEA]] ([[HTTR]]), [[Tsinghua University]] ([[HTR-10]]), X-energy<ref name="energy.gov">{{cite web|title=Energy Department Announces New Investments in Advanced Nuclear Power Reactors...|url=http://www.energy.gov/articles/energy-department-announces-new-investments-advanced-nuclear-power-reactors-help-meet|website=[[United States Department of Energy|US Department of Energy]]|accessdate=16 January 2016}}</ref>
|-
| [[Sodium-cooled fast reactor|SFR]]
| Fast
| Sodium
| 550
| Closed
| 30–150, 300–1500, 1000–2000
|[[TerraPower]] ([[Traveling wave reactor|TWR]]), Toshiba ([[Toshiba 4S|4S]]), [[GE Hitachi Nuclear Energy]] ([[PRISM (reactor)|PRISM]])
|-
| [[Supercritical water reactor|SCWR]]
| Thermal/fast
| Water
| 510–625
| Open/closed
| 300–700, 1000–1500
|
|-
| [[Gas-cooled fast reactor|GFR]]
| Fast
| Helium
| 850
| Closed
| 1200
|
|-
| [[Lead-cooled fast reactor|LFR]]
| Fast
| Lead
| 480–800
| Closed
| 20–180, 300–1200, 600–1000
|
|-
| [[Molten salt reactor|MSR]]
| Fast/thermal
| Fluoride salts
| 700–800
| Closed
| 250, 1000
|[[Flibe Energy]] ([[Liquid fluoride thorium reactor|LFTR]]), [[Transatomic Power]], Thorium Tech Solution ([[Fuji Molten Salt Reactor|FUJI MSR]]), Terrestrial Energy ([[IMSR]]), [[Southern Company Services|Southern Company]]<ref name="energy.gov"/>
|}
<ref>https://www.gen-4.org/gif/upload/docs/application/pdf/2013-09/gif_rd_outlook_for_generation_iv_nuclear_energy_systems.pdf</ref>

=== Thermal reactors ===
A [[Thermal-neutron reactor|thermal reactor]] is a [[nuclear reactor]] that uses slow or [[thermal neutrons]]. A [[neutron moderator]] is used to slow the [[neutron]]s emitted by fission to make them more likely to be captured by the fuel.

==== Very-high-temperature reactor (VHTR) ====
[[File:Very High Temperature Reactor.svg|right|thumb|Very-High-Temperature Reactor (VHTR)]]
{{Main|Very high temperature reactor}}
{{see also|Fort St. Vrain Generating Station|HTTR|HTR-10}}
The '''very high temperature reactor''' concept uses a [[graphite]]-moderated core with a once-through [[uranium]] fuel cycle, using helium or molten salt as the [[Very high temperature reactor#Coolant|coolant]]. This reactor design envisions an outlet temperature of 1,000 °C. The reactor core can be either a prismatic-block or a [[pebble bed reactor]] design. The high temperatures enable applications such as process heat or [[hydrogen]] production via the thermochemical [[Sulfur-iodine cycle|iodine-sulfur]] process. It would also be [[Passive nuclear safety|passively safe]].

The planned construction of the first VHTR, the South African PBMR ([[pebble bed modular reactor]]), lost government funding in February, 2010.<ref>[http://www.powergenworldwide.com/index/display/articledisplay/6322207443/articles/power-engineering-international/volume-18/Issue_3/regulars/world-news/INTERNATIONAL.html South Africa to stop funding Pebble Bed nuclear reactor]</ref> A pronounced increase of costs and concerns about possible unexpected technical problems had discouraged potential investors and customers.

The [[Peoples Republic of China]] began construction of a 200-MW High Temperature Pebble bed reactor in 2012 as a successor to its [[HTR-10]].<ref>[http://www.nucnet.org/all-the-news/2013/01/07/china-begins-construction-of-first-generation-iv-htr-pm-unit Nucnet Report: 'China Begins Construction of First Generation IV HTR-PM Unit', 7 January 2013]</ref>

Also in 2012, as part of the [[Next Generation Nuclear Plant]] competition, [[Idaho National Laboratory]] approved a design similar to [[Areva]]'s prismatic block [http://us.areva.com/EN/home-3225/areva-inc-areva-htgr.html Antares reactor] as the chosen [[HTGR]] to be deployed as a prototype by 2021. It was in competition with [[General Atomics]]' [[Gas turbine modular helium reactor]] and [[Westinghouse Electric Company|Westinghouse]]'s [[Pebble Bed Modular Reactor]].<ref name="World nuclear news">{{cite web|url=http://www.world-nuclear-news.org/NN-Areva_modular_reactor_selected_for_NGNP_development-1502124.html|title=INL approves Antares design}}</ref>

==== Molten-salt reactor (MSR) ====
[[File:Molten Salt Reactor.svg|right|thumb|Molten Salt Reactor (MSR)]]
{{Main|Molten salt reactor}}
{{see also|Liquid fluoride thorium reactor}}
A '''molten salt reactor'''<ref name="Roadmap"/> is a type of [[nuclear reactor]] where the primary [[coolant]], or even the fuel itself is a molten salt mixture. There have been many designs put forward for this type of reactor and a few prototypes built. The early concepts and many current ones rely on [[nuclear fuel]] dissolved in the molten [[fluoride]] salt as [[uranium tetrafluoride]] (UF4) or [[thorium tetrafluoride]] (ThF4). The fluid would reach [[Nuclear reactor physics#Criticality|criticality]] by flowing into a [[graphite]] core which would also serve as the [[neutron moderator|moderator]]. Many current concepts rely on fuel that is dispersed in a graphite matrix with the molten salt providing low pressure, high temperature cooling.

The Gen IV MSR is more accurately termed an [[epithermal neutron|epithermal reactor]] than a thermal reactor due to the average speed of the neutrons that would cause the fission events within its fuel being faster than [[thermal neutron]]s.<ref>{{cite web |url=https://inlportal.inl.gov/portal/server.pt?open=514&objID=1361&parentname=CommunityPage&parentid=10&mode=2&in_hi_userid=200&cached=true |title=Idaho National Laboratory detailing some current efforts at developing Gen. IV reactors}}</ref>

The principle of a MSR can be used for thermal, epithermal and fast reactors. Since 2005 the focus has moved towards a fast spectrum MSR (MSFR).<ref>H. Boussier, S. Delpech, V. Ghetta et Al. : The Molten Salt Reactor (MSR) in Generation IV: Overview and Perspectives, GIF SYMPOSIUM PROCEEDINGS/2012 ANNUAL REPORT, NEA No. 7141, pp95 [https://www.gen-4.org/gif/jcms/c_44720/annual-reports]
</ref>

While most MSR designs being pursued are largely derived from the 1960s [[Molten-Salt Reactor Experiment]](MSRE), variants of molten salt technology include the conceptual ''[[Dual fluid reactor]]'' which is being designed with lead as a cooling medium but molten salt fuel, commonly as the metal chloride e.g [[Plutonium(III) chloride]], to aid in greater "waste" plutonium [[transmutation]]. While other notable approaches differing substantially from those with MSRE [[pedigree]] include the ''Stable Salt Reactor''(SSR) concept promoted by MOLTEX, which encases the molten salt in hundreds of the common solid [[fuel rod]]s that are already well established in the nuclear industry. This latter British design was found to be the most competitive for [[Small modular reactor]] development by a British based consultancy firm ''Energy Process Development'' in 2015.<ref>[http://www.daretothink.org/europe-moltex-stable-salt-reactor/ Europe: Moltex’ Stable Salt Reactor]</ref><ref>[http://analysis.nuclearenergyinsider.com/moltex-energy-sees-uk-canada-smr-licensing-springboard-asia Moltex Energy sees UK, Canada SMR licensing as springboard to Asia
Jun 28, 2016]</ref>

==== Supercritical-water-cooled reactor (SCWR) ====
[[File:Supercritical-Water-Cooled Reactor.svg|right|thumb|Supercritical-Water-Cooled Reactor (SCWR)]]
{{Main|Supercritical water reactor}}
The '''supercritical water reactor''' (SCWR)<ref name="Roadmap"/> is a [[reduced moderation water reactor]] concept that, due to the average speed of the neutrons that would cause the fission events within the fuel being faster than [[thermal neutron]]s, it is more accurately termed an [[epithermal neutron|epithermal reactor]] than a thermal reactor. It uses [[supercritical fluid|supercritical water]] as the working fluid. SCWRs are basically [[light water reactor]]s (LWR) operating at higher pressure and temperatures with a direct, once-through heat exchange cycle. As most commonly envisioned, it would operate on a direct cycle, much like a boiling water reactor ([[BWR]]), but since it uses supercritical water (not to be confused with [[Critical mass (nuclear)|critical mass]]) as the working fluid, it would have only one water phase present, which makes the supercritical heat exchange method more similar to a pressurized water reactor ([[Pressurized water reactor|PWR]]). It could operate at much higher temperatures than both current PWRs and BWRs.

Supercritical water-cooled reactors (SCWRs) are promising advanced nuclear systems because of their high [[thermal efficiency]] (i.e., about 45% vs. about 33% efficiency for current LWRs) and considerable plant simplification.

The main mission of the SCWR is generation of low-cost [[electricity]]. It is built upon two proven technologies, LWRs, which are the most commonly deployed power generating reactors in the world, and superheated [[fossil fuel]] fired [[boiler]]s, a large number of which are also in use around the world. The SCWR concept is being investigated by 32 organizations in 13 countries.{{citation needed|date=October 2012}}

A SCWR Design under development is the [[VVER]]-1700/393 (VVER-SCWR or VVER-SKD) — a Russian Supercritical-water-cooled reactor with double-inlet-core and a [[breeder reactor|breeding ratio]] of 0.95.<ref name="powertecrussia.com">{{cite web |url=http://www.powertecrussia.com/blog/tag/nuclear-power/ |title=Technology Developments & Plant Efficiency for the Russian Nuclear Power Generation Market Wednesday |date=March 24, 2010}}</ref>

=== Fast reactors ===
A [[Fast-neutron reactor|fast reactor]] directly uses the fast neutrons emitted by fission, without moderation. Unlike thermal neutron reactors, fast neutron reactors can be configured to "'''burn'''", or fission, all [[actinides]], and given enough time, therefore drastically reduce the actinides fraction in [[spent nuclear fuel]] produced by the present world fleet of thermal neutron [[light water reactor]]s, thus closing the [[nuclear fuel cycle]]. Alternatively, if configured differently, they can also [[breeder reactor|'''breed''']] more actinide fuel than they consume.

==== Gas-cooled fast reactor (GFR) ====
[[File:Gas-Cooled Fast Reactor Schemata.svg|right|thumb|Gas-Cooled Fast Reactor (GFR)]]
{{Main|Gas-cooled fast reactor}}
The '''gas-cooled fast reactor''' (GFR)<ref name="Roadmap"/> system features a fast-neutron spectrum and closed fuel cycle for efficient conversion of [[Fertile material|fertile uranium]] and management of actinides. The reactor is [[helium]]-cooled and with an outlet temperature of 850 °C it is an evolution of the [[very-high-temperature reactor]] (VHTR) to a more sustainable fuel cycle. It will use a direct [[Brayton cycle]] [[Closed-cycle gas turbine|gas turbine]] for high thermal efficiency. Several fuel forms are being considered for their potential to operate at very high temperatures and to ensure an excellent retention of [[Nuclear fission|fission]] products: composite [[ceramic]] fuel, advanced fuel particles, or ceramic clad elements of actinide compounds. Core configurations are being considered based on pin- or plate-based fuel assemblies or prismatic blocks.

The European Sustainable Nuclear Industrial Initiative is funding three Generation IV reactor systems, one of which is a gas-cooled fast reactor, called ''Allegro'', 100 MW(t), which will be built in a central or eastern European country with construction expected to begin in 2018.<ref name="euronuclear.org">{{cite web |url=https://www.euronuclear.org/1-information/news/Gen-IV.htm |title=The European Sustainable Nuclear Industrial Initiative (ESNII) will support three Generation IV reactor systems: a sodium-cooled fast reactor, or SFR, called ''Astrid'' that is proposed by France; a gas-cooled fast reactor, GFR, called ''Allegro'' supported by central and eastern Europe; and a lead-cooled fast reactor, LFR, technology pilot called ''Myrrha'' that is proposed by Belgium.}}</ref> The central European [[Visegrád Group]] are committed to pursuing the technology.<ref>{{cite web |url=http://www.alphagalileo.org/ViewItem.aspx?ItemId=133111&CultureCode=en |title=The V4G4 Centre of Excellence for performing joint research, development and innovation in the field of Generation-4 (G4) nuclear reactors have been established. 20 July 2013 National Center for Nuclear Research (NCBJ]}}</ref> In 2013 German, British, and French institutes finished a 3-year collaboration study on the follow on industrial scale design, known as ''GoFastR''.<ref>{{cite web |url=http://www.ist-world.org/ProjectDetails.aspx?ProjectId=5cb8f3f283574cc6b2bdbf72533172d8 |title=the European Gas cooled Fast Reactor.}}</ref> They were funded by the EU's 7th FWP [[framework programme]], with the goal of making a sustainable VHTR.<ref>{{cite web |url=http://www.2020-horizon.com/GOFASTR-European-Gas-Cooled-Fast-Reactor%28GOFASTR%29-s312.html |title=The GOFASTR research program}}</ref>

==== Sodium-cooled fast reactor (SFR) ====
[[File:Sodium-Cooled Fast Reactor Schemata.svg|right|thumb|Pool design Sodium-Cooled Fast Reactor (SFR)]]
{{Main|Sodium-cooled fast reactor}}
{{see also|Experimental Breeder Reactor II|S-PRISM|BN-800 reactor|Toshiba 4S}}
The SFR<ref name="Roadmap"/> is a project that builds on two closely related existing projects, the liquid metal [[Breeder reactor#Fast breeder reactor|fast breeder reactor]] and the [[integral fast reactor]].

The goals are to increase the efficiency of uranium usage by [[breeder reactor|breeding]] plutonium and eliminating the need for [[transuranic]] isotopes ever to leave the site. The reactor design uses an unmoderated core running on [[fast neutron]]s, designed to allow any transuranic isotope to be consumed (and in some cases used as fuel). In addition to the benefits of removing the long [[half-life]] transuranics from the waste cycle, the SFR fuel expands when the reactor overheats, and the chain reaction automatically slows down. In this manner, it is passively safe.<ref>{{cite web |url=http://www.ne.anl.gov/About/hn/logos-winter02-psr.shtml|title=Passively safe reactors rely on nature to keep them cool|author=David Baurac}}</ref>

The SFR reactor concept is cooled by liquid [[sodium]] and fueled by a metallic alloy of uranium and [[plutonium]] or [[spent nuclear fuel]], the "nuclear waste" of [[light water reactor]]s. The SFR fuel is contained in steel cladding with liquid sodium filling in the space between the clad elements which make up the fuel assembly. One of the design challenges of an SFR is the risks of handling sodium, which reacts explosively if it comes into contact with water. However, the use of liquid metal instead of water as coolant allows the system to work at atmospheric pressure, reducing the risk of leakage.

The European Sustainable Nuclear Industrial Initiative is funding three Generation IV reactor systems, one of which is a sodium-cooled fast reactor, called ''[[ASTRID (reactor)|ASTRID]]'', Advanced Sodium Technical Reactor for Industrial Demonstration, [[Areva]], [[Commissariat à l'énergie atomique et aux énergies alternatives|CEA]] and [[Électricité de France|EDF]] are leading the design with British collaboration.<ref>{{cite web |url=http://www.power-eng.com/articles/2010/11/areva--cea-secure.html |title=Areva, CEA secure EUR650m funding to develop ASTRID sodium-cooled Generation IV reactor 11/11/2010}}</ref><ref>{{cite web |url=http://www.powermag.com/uk-and-france-sign-landmark-civil-nuclear-cooperation-agreement/ |title=UK and France Sign Landmark Civil Nuclear Cooperation Agreement 02/22/2012 . POWERnews}}</ref> Astrid will be rated about 600 MWe and is proposed to be built in France, near to the [[Phénix]] reactor. A final decision in construction is to be made in 2019<ref name="euronuclear.org"/>

The [[China|PRC]]'s first commercial-scale, 800 MWe, fast neutron reactor, to be situated near [[Sanming]] in [[Fujian province]] will be a SFR. In 2009 an agreement was signed that would entail the Russian [[BN-800 reactor]] design to be sold to the PRC once it is completed, this would be the first time commercial-scale fast neutron reactors have ever been exported.<ref>{{cite web |url=http://www.world-nuclear-news.org/C-Joint_venture_launched_for_Chinese_fast_reactor-3004104.html |title=Joint venture launched for Chinese fast reactor}}</ref> The BN-800 reactor became operational in 2014.

In India, the [[Prototype Fast Breeder Reactor]], a 500 MWe Sodium cooled fast reactor is being built at a cost of INR 5,677 crores (~US$900 million) and is expected to be commissioned by September 2016. The PFBR will be followed by six more Commercial Fast Breeder Reactors (CFBRs) of 500 MWe each.

The 400 MWe [[Fast Flux Test Facility]] operated successfully for ten years at the Hanford site in Washington State.

The 20 MWe [[EBR II]] operated successfully for over thirty years at the Idaho National Laboratory, until it was shut down in 1994.

==== Lead-cooled fast reactor (LFR) ====
[[File:Lead-Cooled Fast Reactor Schemata.svg|right|thumb|Lead-Cooled Fast Reactor (LFR)]]
{{Main|Lead-cooled fast reactor}}
{{See also|MYRRHA}}
The '''lead-cooled fast reactor'''<ref name="Roadmap">{{cite journal| year=2002 | title=A Technology Roadmap for Generation IV Nuclear Energy Systems | last=US DOE Nuclear Energy Research Advisory Committee |volume=GIF-002-00|url=http://nuclear.energy.gov/genIV/documents/gen_iv_roadmap.pdf}}</ref> features a fast-neutron-spectrum [[lead]] or [[lead]]/[[bismuth]] [[eutectic]] ([[Lead-bismuth eutectic|LBE]]) liquid-metal-cooled reactor with a closed [[Nuclear fuel cycle|fuel cycle]]. Options include a range of plant ratings, including a "battery" of 50 to 150 MW of electricity that features a very long refueling interval, a modular system rated at 300 to 400 MW, and a large monolithic plant option at 1,200 MW. (The term ''battery'' refers to the long-life, factory-fabricated core, not to any provision for electrochemical energy conversion.) The fuel is metal or nitride-based containing [[Fertile material|fertile uranium]] and [[transuranic]]s. The LFR is cooled by natural [[convection]] with a reactor outlet coolant temperature of 550 °C, possibly ranging up to 800 °C with advanced materials. The higher temperature enables the production of [[Thermochemical cycle|hydrogen by thermochemical processes]].

The European Sustainable Nuclear Industrial Initiative is funding three Generation IV reactor systems, one of which is a lead-cooled fast reactor that is also an [[Subcritical reactor|accelerator-driven sub-critical]] reactor, called ''[[MYRRHA]]'', 100 MW(t), which will be built in [[Belgium]] with construction expected to begin after 2014 and the industrial scale version, known as ''Alfred'', slated to be constructed sometime after 2017. A reduced-power model of Myrrha called ''Guinevere'' was started up at [[Mol, Belgium|Mol]] in March 2009.<ref name="euronuclear.org"/> In 2012 the research team reported that Guinevere was operational.<ref>{{cite news|last1=Hellemans|first1=Alexander|title=Reactor-Accelerator Hybrid Achieves Successful Test Run|url=http://news.sciencemag.org/physics/2012/01/reactor-accelerator-hybrid-achieves-successful-test-run|accessdate=29 December 2014|work=Science Insider|date=12 January 2012}}</ref>

Two other lead-cooled fast reactors under development are the SVBR-100, a modular 100 MWe lead-bismuth cooled fast neutron reactor concept designed by OKB [[Gidropress]] in Russia and the BREST-OD-300 (Lead-cooled fast reactor) 300 MWe, to be developed after the SVBR-100, and built over 2016-20, it will dispense with the [[Uranium-238|fertile blanket]] around the core and will supersede the sodium cooled [[BN-600 reactor]] design, to purportedly give enhanced proliferation resistance.<ref name="powertecrussia.com"/>

== Advantages and disadvantages ==
Relative to current nuclear power plant technology, the claimed benefits for 4th generation reactors include:
* Nuclear waste that remains radioactive for a few centuries instead of millennia<ref>{{cite web |title=Strategies to Address Global Warming |url=http://www.columbia.edu/~jeh1/mailings/2009/20090713_Strategies.pdf}}</ref>
* 100-300 times more energy yield from the same amount of nuclear fuel<ref>{{cite web |title=4th Generation Nuclear Power |url=http://www.ossfoundation.us/projects/energy/nuclear}}</ref>
* Broader range of fuels, and even unencapsulated raw fuels (non-pebble [[Molten Salt Reactor|MSR]], [[LFTR]]).
* In some reactors, the ability to consume existing nuclear waste in the production of electricity, that is, a Closed [[nuclear fuel cycle]]. This strengthens the argument to deem [[nuclear power as renewable energy]].
* Improved operating safety features, such as (depending on design) avoidance of pressurized operation, automatic passive (unpowered, uncommanded) reactor shutdown, avoidance of water cooling and the associated risks of loss of water (leaks or boiling) and hydrogen generation/explosion and contamination of coolant water.

Nuclear reactors do not emit CO2 during operation, although like all [[low carbon power]] sources, the mining and construction phase can result in CO2 emissions, if energy sources which are not carbon neutral (such as fossil fuels), or CO2 emitting cements are used during the construction process.
A 2012 [[Yale University]] review published in the Journal of Industrial Ecology analyzing {{CO2}} [[life cycle assessment]] (LCA) emissions from [[nuclear power]] determined that:<ref name="Warner + Heath, JoIE">Warner, Ethan S.; Heath, Garvin A. [http://onlinelibrary.wiley.com/doi/10.1111/j.1530-9290.2012.00472.x/full Life Cycle Greenhouse Gas Emissions of Nuclear Electricity Generation: Systematic Review and Harmonization], ''Journal of Industrial Ecology'', [[Yale University]], published online April 17, 2012, doi: 10.1111/j.1530-9290.2012.00472.x.</ref>
{{Quote|''"The collective LCA literature indicates that life cycle [[Greenhouse gas|GHG]] [ greenhouse gas ] emissions from nuclear power are only a fraction of traditional fossil sources and comparable to renewable technologies."''}}
Although the paper primarily dealt with data from [[Generation II reactor]]s, and did not analyze the {{CO2}} emissions by 2050 of the presently under construction [[Generation III reactor]]s, it did summarize the Life Cycle Assessment findings of in development reactor technologies.''{{Quote|FBRs ''[ [[Fast Breeder Reactor]]s ]'' have been evaluated in the LCA literature. The limited literature that evaluates this potential future technology reports [[median]] life cycle GHG emissions... similar to or lower than LWRs[ Gen II [[light water reactor]]s ] and purports to consume little or no [[uranium market|uranium ore]].}}

A specific risk of the sodium-cooled fast reactor is related to using metallic sodium as a coolant. In case of a breach, sodium explosively reacts with water. Fixing breaches may also prove dangerous, as the cheapest noble gas [[argon]] is also used to prevent sodium oxidation. Argon, like helium, can displace oxygen in the air and can pose [[hypoxia (environmental)|hypoxia]] concerns, so workers may be exposed to this additional risk. This is a pertinent problem as can be testified by the events at the [[LMFBR|loop type]] [[Monju Nuclear Power Plant|Prototype Fast Breeder Reactor Monju]] at Tsuruga, Japan.<ref>{{cite news |title=Japan Strains to Fix a Reactor Damaged Before Quake |url=http://www.nytimes.com/2011/06/18/world/asia/18japan.html | work=The New York Times | first=Hiroko |last=Tabuchi |date=17 June 2011}}</ref>
Using lead or molten salts mitigates this problem by making the coolant less reactive and allowing a high freezing temperature and low pressure in case of a leak. Disadvantages of lead compared to sodium are much higher viscosity, much higher density, lower heat capacity, and more radioactive neutron activation products.

In many cases, there is already a large amount of experience built up with numerous proof of concept Gen IV designs. For example, the reactors at [[Fort St. Vrain Generating Station]] and [[HTR-10]] are similar to the proposed Gen IV [[VHTR]] designs, and the [[LMFBR|pool type]] [[EBR-II]], [[Phénix]] and [[BN-600]] reactor are similar to the proposed pool type Gen IV Sodium Cooled Fast reactors being designed.

== See also ==
{{colbegin|3}}
* [[Nuclear reactor]]
* [[Nuclear material]]
* [[Nuclear physics]]
* [[List of reactor types#Reactor types|List of reactor types]]
* [[Generation II reactor]]
* [[Generation III reactor]]
* [[Integral Fast Reactor]]
* [[Liquid fluoride thorium reactor]]
* [[Breeder reactor]]
* [[Small modular reactor]]
{{colend}}

==References==
{{Reflist|30em}}

== External links ==
* [https://inlportal.inl.gov/portal/server.pt?open=514&objID=1361&parentname=CommunityPage&parentid=10&mode=2&in_hi_userid=200&cached=true Article from Idaho National Laboratory detailing some current efforts at developing Gen. IV reactors.]
* [http://www.gen-4.org/ Generation IV International Forum (GIF)]
* [http://nuclear.energy.gov/genIV/neGenIV1.html U.S. Department of Energy Office of Nuclear Energy, Science and Technology]
* [http://www.engr.utk.edu/nuclear/colloquia/slides/Gen%20IV%20U-Tenn%20Presentation.pdf Gen IV presentation]
* [http://www.ecology.at/ecology/files/pr577_1.pdf Science or Fiction - Is there a Future for Nuclear?] (Nov. 2007) - A publication from the Austrian [[Ecology Institute (Austria)|Ecology Institute]] about 'Generation IV' and Fusion reactors.
* {{cite web |url=http://memagazine.asme.org/Articles/2011/December/Nuclear_Power_After_Fukushima.cfm |title=Nuclear Power After Fukushima |author=Gail H. Marcus |date=December 2011 |work=Mechanical Engineering (the magazine of [[ASME]]) |accessdate=23 January 2012}} "In the wake of a severe plant accident, advanced reactor designs are getting renewed attention."
* [http://www.itheo.org/ International Thorium Energy Organisation - www.IThEO.org]
* [http://www.ithec.org/ International Thorium Energy Committee - iThEC]

{{Nuclear fission reactors}}

[[Category:Nuclear power reactor types]]
[[Category:Idaho National Laboratory]]

Benutzer:Snackroeg/Kernreaktoren der Generation 5

2015-08-17T05:49:52Z

Boundarylayer:

[[File:GenIVRoadmap-en.svg|thumb|480px|Nuclear Energy Systems Deployable no later than 2030 and offering significant advances in sustainability, safety and reliability, and economics]]

'''Generation IV reactors''' (Gen IV) are a set of [[nuclear reactor]] designs currently being researched for commercial applications, with depending on the particular design, [[Technology readiness level]]s varying between the level requiring a demonstration, to economical competitive implementation. Most of these designs, with the exception of the [[BN-1200 reactor]], are generally not expected to be available for commercial construction before 2030-40.<ref name="Generation IV">[http://www.world-nuclear.org/info/Nuclear-Fuel-Cycle/Power-Reactors/Generation-IV-Nuclear-Reactors/]</ref> Presently the majority of reactors in operation around the world are considered [[Generation II reactor|second generation reactor]] systems, as the vast majority of the [[Generation I reactor|first-generation]] systems were retired some time ago, and there are only a dozen or so [[Generation III reactors]] in operation (2014). [[Nuclear reactor#Generation V+ reactors|Generation V reactors]] refer to reactors that are purely theoretical and are therefore not yet considered feasible in the short term, resulting in limited [[R&D]] funding.

== Reactor types ==
Many reactor types were considered initially; however, the list was downsized to focus on the most promising technologies and those that could most likely meet the goals of the Gen IV initiative.<ref name="Generation IV"/> Three systems are nominally [[thermal reactor]]s and three are [[fast reactor]]s. The Very High Temperature Reactor (VHTR) is also being researched for potentially providing high quality process heat for [[thermochemical cycle|hydrogen production]]. The fast reactors offer the possibility of burning [[actinides]] to further reduce waste and of being able to "[[breeder reactor|breed more fuel]]" than they consume. These systems offer significant advances in sustainability, safety and reliability, economics, proliferation resistance (depending on perspective) and physical protection.

{| class=wikitable
|-
! System
! Neuron Spectrum
! Coolant
! Temperature
! Fuel Cycle
! Size
|-
| VHTR
| Thermal
| Helium
| 900-1000
| Open
| 250-300
|-
| SFR
| Fast
| Sodium
| 550
| Closed
| 30-150, 300-1500, 1000-2000
|-
| SCWR
| Thermal/fast
| Water
| 510-625
| Open/closed
| 300-700, 1000-1500
|-
| GFR
| Fast
| Helium
| 850
| Closed
| 1200
|-
| LFR
| Fast
| Lead
| 480-800
| Closed
| 20-180, 300-1200, 600-1000
|-
| MSR
| Fast/thermal
| Fluoride salts
| 700-800
| Closed
| 1000
|}
<ref>https://www.gen-4.org/gif/upload/docs/application/pdf/2013-09/gif_rd_outlook_for_generation_iv_nuclear_energy_systems.pdf</ref>
=== Thermal reactors ===
A [[Thermal-neutron reactor|thermal reactor]] is a [[nuclear reactor]] that uses slow or [[thermal neutrons]]. A [[neutron moderator]] is used to slow the [[neutron]]s emitted by fission to make them more likely to be captured by the fuel.

==== Very-high-temperature reactor (VHTR) ====
[[File:Very High Temperature Reactor.svg|right|thumb|Very-High-Temperature Reactor (VHTR)]]
{{Main|Very high temperature reactor}}
{{see also|Fort St. Vrain Generating Station|HTTR|HTR-10}}
The '''very high temperature reactor''' concept uses a [[graphite]]-moderated core with a once-through [[uranium]] fuel cycle, using helium or molten salt as the [[Very high temperature reactor#Coolant|coolant]]. This reactor design envisions an outlet temperature of 1,000 °C. The reactor core can be either a prismatic-block or a [[pebble bed reactor]] design. The high temperatures enable applications such as process heat or [[hydrogen]] production via the thermochemical [[Sulfur-iodine cycle|iodine-sulfur]] process. It would also be [[Passive nuclear safety|passively safe]].

The planned construction of the first VHTR, the South African PBMR ([[pebble bed modular reactor]]), lost government funding in February, 2010.<ref>[http://www.powergenworldwide.com/index/display/articledisplay/6322207443/articles/power-engineering-international/volume-18/Issue_3/regulars/world-news/INTERNATIONAL.html South Africa to stop funding Pebble Bed nuclear reactor]</ref> A pronounced increase of costs and concerns about possible unexpected technical problems had discouraged potential investors and customers.

The [[Peoples Republic of China]] began construction of a 200-MWe High Temperature Pebble bed reactor in 2012 as a successor to its [[HTR-10]].<ref>[http://www.nucnet.org/all-the-news/2013/01/07/china-begins-construction-of-first-generation-iv-htr-pm-unit Nucnet Report: 'China Begins Construction of First Generation IV HTR-PM Unit', 7 January 2013]</ref>

Also in 2012, as part of the [[Next Generation Nuclear Plant]] competition, [[Idaho National Laboratory]] approved a design similar to [[Areva]]'s prismatic block [http://de.areva.com/EN/areva-germany-312/future-reactor-concepts.html Antares reactor] as the chosen [[HTGR]] to be deployed as a prototype by 2021. It was in competition with [[General Atomics]]' [[Gas turbine modular helium reactor]] and [[Westinghouse Electric Company|Westinghouse]]'s [[Pebble Bed Modular Reactor]].<ref name="World nuclear news">{{cite web|url=http://www.world-nuclear-news.org/NN-Areva_modular_reactor_selected_for_NGNP_development-1502124.html|title=INL approves Antares design}}</ref>

==== Molten-salt reactor (MSR) ====
[[File:Molten Salt Reactor.svg|right|thumb|Molten Salt Reactor (MSR)]]
{{Main|Molten salt reactor}}
{{see also|Liquid fluoride thorium reactor}}
A '''molten salt reactor'''<ref name="Roadmap"/> is a type of [[nuclear reactor]] where the primary [[coolant]], or even the fuel itself is a molten salt mixture. There have been many designs put forward for this type of reactor and a few prototypes built. The early concepts and many current ones rely on [[nuclear fuel]] dissolved in the molten [[fluoride]] salt as [[uranium tetrafluoride]] (UF4) or [[thorium tetrafluoride]] (ThF4). The fluid would reach [[Nuclear reactor physics#Criticality|criticality]] by flowing into a [[graphite]] core which would also serve as the [[neutron moderator|moderator]]. Many current concepts rely on fuel that is dispersed in a graphite matrix with the molten salt providing low pressure, high temperature cooling.

The Gen IV MSR is more accurately termed an [[epithermal neutron|epithermal reactor]] than a thermal reactor due to the average speed of the neutrons that would cause the fission events within its fuel being faster than [[thermal neutron]]s.<ref>{{cite web |url=https://inlportal.inl.gov/portal/server.pt?open=514&objID=1361&parentname=CommunityPage&parentid=10&mode=2&in_hi_userid=200&cached=true |title=Idaho National Laboratory detailing some current efforts at developing Gen. IV reactors}}</ref>

The principle of a MSR can be used for thermal, epithermal and fast reactors. Since 2005 the focus has moved towards a fast spectrum MSR (MSFR).
<ref>H. Boussier, S. Delpech, V. Ghetta et Al. : The Molten Salt Reactor (MSR) in Generation IV: Overview and Perspectives, GIF SYMPOSIUM PROCEEDINGS/2012 ANNUAL REPORT, NEA No. 7141, pp95 [https://www.gen-4.org/gif/jcms/c_44720/annual-reports]
</ref>

==== Supercritical-water-cooled reactor (SCWR) ====
[[File:Supercritical-Water-Cooled Reactor.svg|right|thumb|Supercritical-Water-Cooled Reactor (SCWR)]]
{{Main|Supercritical water reactor}}
The '''supercritical water reactor''' (SCWR)<ref name="Roadmap"/> is a [[reduced moderation water reactor]] concept that, due to the average speed of the neutrons that would cause the fission events within the fuel being faster than [[thermal neutron]]s, it is more accurately termed an [[epithermal neutron|epithermal reactor]] than a thermal reactor. It uses [[supercritical fluid|supercritical water]] as the working fluid. SCWRs are basically [[light water reactor]]s (LWR) operating at higher pressure and temperatures with a direct, once-through heat exchange cycle. As most commonly envisioned, it would operate on a direct cycle, much like a boiling water reactor ([[BWR]]), but since it uses supercritical water (not to be confused with [[Critical mass (nuclear)|critical mass]]) as the working fluid, it would have only one water phase present, which makes the supercritical heat exchange method more similar to a pressurized water reactor ([[Pressurized water reactor|PWR]]). It could operate at much higher temperatures than both current PWRs and BWRs.

Supercritical water-cooled reactors (SCWRs) are promising advanced nuclear systems because of their high [[thermal efficiency]] (i.e., about 45% vs. about 33% efficiency for current LWRs) and considerable plant simplification.

The main mission of the SCWR is generation of low-cost [[electricity]]. It is built upon two proven technologies, LWRs, which are the most commonly deployed power generating reactors in the world, and superheated [[fossil fuel]] fired [[boiler]]s, a large number of which are also in use around the world. The SCWR concept is being investigated by 32 organizations in 13 countries.{{citation needed|date=October 2012}}

A SCWR Design under development is the [[VVER]]-1700/393 (VVER-SCWR or VVER-SKD) — a Russian Supercritical-water-cooled reactor with double-inlet-core and a [[breeder reactor|breeding ratio]] of 0.95.<ref name="powertecrussia.com">{{cite web |url=http://www.powertecrussia.com/blog/tag/nuclear-power/ |title=Technology Developments & Plant Efficiency for the Russian Nuclear Power Generation Market Wednesday |date=March 24, 2010}}</ref>

=== Fast reactors ===
A [[Fast-neutron reactor|fast reactor]] directly uses the fast neutrons emitted by fission, without moderation. Unlike thermal neutron reactors, fast neutron reactors can be configured to "burn", or fission, all [[actinides]], and given enough time, therefore drastically reduce the actinides fraction in [[spent nuclear fuel]] produced by the present world fleet of thermal neutron [[light water reactor]]s, thus closing the [[nuclear fuel cycle]]. Alternatively, if configured differently, they can also [[breeder reactor|breed]] more actinide fuel than they consume.

==== Gas-cooled fast reactor (GFR) ====
[[File:Gas-Cooled Fast Reactor Schemata.svg|right|thumb|Gas-Cooled Fast Reactor (GFR)]]
{{Main|Gas-cooled fast reactor}}
The '''gas-cooled fast reactor''' (GFR)<ref name="Roadmap"/> system features a fast-neutron spectrum and closed fuel cycle for efficient conversion of [[Fertile material|fertile uranium]] and management of actinides. The reactor is [[helium]]-cooled and with an outlet temperature of 850 °C it is an evolution of the [[very-high-temperature reactor]] (VHTR) to a more sustainable fuel cycle. It will use a direct [[Brayton cycle]] [[Closed-cycle gas turbine|gas turbine]] for high thermal efficiency. Several fuel forms are being considered for their potential to operate at very high temperatures and to ensure an excellent retention of [[Nuclear fission|fission]] products: composite [[ceramic]] fuel, advanced fuel particles, or ceramic clad elements of actinide compounds. Core configurations are being considered based on pin- or plate-based fuel assemblies or prismatic blocks.

The European Sustainable Nuclear Industrial Initiative is funding three Generation IV reactor systems, one of which is a gas-cooled fast reactor, called ''Allegro'', 100 MW(t), which will be built in a central or eastern European country with construction expected to begin in 2018.<ref name="euronuclear.org">{{cite web |url=https://www.euronuclear.org/1-information/news/Gen-IV.htm |title=The European Sustainable Nuclear Industrial Initiative (ESNII) will support three Generation IV reactor systems: a sodium-cooled fast reactor, or SFR, called ''Astrid'' that is proposed by France; a gas-cooled fast reactor, GFR, called ''Allegro'' supported by central and eastern Europe; and a lead-cooled fast reactor, LFR, technology pilot called ''Myrrha'' that is proposed by Belgium.}}</ref> The central European [[Visegrád Group]] are committed to pursuing the technology.<ref>{{cite web |url=http://www.alphagalileo.org/ViewItem.aspx?ItemId=133111&CultureCode=en |title=The V4G4 Centre of Excellence for performing joint research, development and innovation in the field of Generation-4 (G4) nuclear reactors have been established. 20 July 2013 National Center for Nuclear Research (NCBJ]}}</ref> In 2013 German, British, and French institutes finished a 3-year collaboration study on the follow on industrial scale design, known as ''GoFastR''.<ref>{{cite web |url=http://www.ist-world.org/ProjectDetails.aspx?ProjectId=5cb8f3f283574cc6b2bdbf72533172d8 |title=the European Gas cooled Fast Reactor.}}</ref> They were funded by the EU's 7th FWP [[framework programme]], with the goal of making a sustainable VHTR.<ref>{{cite web |url=http://www.2020-horizon.com/GOFASTR-European-Gas-Cooled-Fast-Reactor%28GOFASTR%29-s312.html |title=The GOFASTR research program}}</ref>

==== Sodium-cooled fast reactor (SFR) ====
[[File:Sodium-Cooled Fast Reactor Schemata.svg|right|thumb|Pool design Sodium-Cooled Fast Reactor (SFR)]]
{{Main|Sodium-cooled fast reactor}}
{{see also|Experimental Breeder Reactor II|S-PRISM|BN-800 reactor|Toshiba 4S}}
The SFR<ref name="Roadmap"/> is a project that builds on two closely related existing projects, the liquid metal [[Breeder reactor#Fast breeder reactor|fast breeder reactor]] and the [[integral fast reactor]].

The goals are to increase the efficiency of uranium usage by [[breeder reactor|breeding]] plutonium and eliminating the need for [[transuranic]] isotopes ever to leave the site. The reactor design uses an unmoderated core running on [[fast neutron]]s, designed to allow any transuranic isotope to be consumed (and in some cases used as fuel). In addition to the benefits of removing the long [[half-life]] transuranics from the waste cycle, the SFR fuel expands when the reactor overheats, and the chain reaction automatically slows down. In this manner, it is passively safe.<ref>{{cite web |url=http://www.ne.anl.gov/About/hn/logos-winter02-psr.shtml|title=Passively safe reactors rely on nature to keep them cool|author=David Baurac}}</ref>

The SFR reactor concept is cooled by liquid [[sodium]] and fueled by a metallic alloy of uranium and [[plutonium]] or [[spent nuclear fuel]], the "nuclear waste" of [[light water reactor]]s. The SFR fuel is contained in steel cladding with liquid sodium filling in the space between the clad elements which make up the fuel assembly. One of the design challenges of an SFR is the risks of handling sodium, which reacts explosively if it comes into contact with water. However, the use of liquid metal instead of water as coolant allows the system to work at atmospheric pressure, reducing the risk of leakage.

The European Sustainable Nuclear Industrial Initiative is funding three Generation IV reactor systems, one of which is a sodium-cooled fast reactor, called ''[[ASTRID (reactor)|ASTRID]]'', Advanced Sodium Technical Reactor for Industrial Demonstration, [[Areva]], [[Commissariat à l'énergie atomique et aux énergies alternatives|CEA]] and [[Électricité de France|EDF]] are leading the design with British collaboration.<ref>{{cite web |url=http://www.power-eng.com/articles/2010/11/areva--cea-secure.html |title=Areva, CEA secure EUR650m funding to develop ASTRID sodium-cooled Generation IV reactor 11/11/2010}}</ref><ref>{{cite web |url=http://www.powermag.com/uk-and-france-sign-landmark-civil-nuclear-cooperation-agreement/ |title=UK and France Sign Landmark Civil Nuclear Cooperation Agreement 02/22/2012 . POWERnews}}</ref> Astrid will be rated about 600 MWe and is proposed to be built in France, near to the [[Phénix]] reactor. A final decision in construction is to be made in 2019<ref name="euronuclear.org"/>

The [[China|PRC]]'s first commercial-scale, 800 MWe, fast neutron reactor, to be situated near [[Sanming]] in [[Fujian province]] will be a SFR. In 2009 an agreement was signed that would entail the Russian [[BN-800 reactor]] design to be sold to the PRC once it is completed, this would be the first time commercial-scale fast neutron reactors have ever been exported.<ref>{{cite web |url=http://www.world-nuclear-news.org/C-Joint_venture_launched_for_Chinese_fast_reactor-3004104.html |title=Joint venture launched for Chinese fast reactor}}</ref> The BN-800 reactor became operational in 2014.

In India, the [[Prototype Fast Breeder Reactor]], a 500MWe Sodium cooled fast reactor is being built at a cost of INR 5,677 crores (~US$900 million) and is expected to be commissioned by September 2016. The PFBR will be followed by six more Commercial Fast Breeder Reactors (CFBRs) of 500 MWe each.

The 400MWe [[Fast Flux Test Facility]] operated successfully for ten years at the Hanford site in Washington State.

The 20 MWe [[EBR II]] operated successfully for over thirty years at the Idaho National Laboratory, until it was shut down in 1994.

==== Lead-cooled fast reactor (LFR) ====
[[File:Lead-Cooled Fast Reactor Schemata.svg|right|thumb|Lead-Cooled Fast Reactor (LFR)]]
{{Main|Lead-cooled fast reactor}}
{{See also|MYRRHA}}
The '''lead-cooled fast reactor'''<ref name="Roadmap">{{cite journal| year=2002 | title=A Technology Roadmap for Generation IV Nuclear Energy Systems | last=US DOE Nuclear Energy Research Advisory Committee |volume=GIF-002-00|url=http://nuclear.energy.gov/genIV/documents/gen_iv_roadmap.pdf}}</ref> features a fast-neutron-spectrum [[lead]] or [[lead]]/[[bismuth]] [[eutectic]] ([[Lead-bismuth eutectic|LBE]]) liquid-metal-cooled reactor with a closed [[Nuclear fuel cycle|fuel cycle]]. Options include a range of plant ratings, including a "battery" of 50 to 150 MW of electricity that features a very long refueling interval, a modular system rated at 300 to 400 MW, and a large monolithic plant option at 1,200 MW. (The term ''battery'' refers to the long-life, factory-fabricated core, not to any provision for electrochemical energy conversion.) The fuel is metal or nitride-based containing [[Fertile material|fertile uranium]] and [[transuranic]]s. The LFR is cooled by natural [[convection]] with a reactor outlet coolant temperature of 550 °C, possibly ranging up to 800 °C with advanced materials. The higher temperature enables the production of [[Thermochemical cycle|hydrogen by thermochemical processes]].

The European Sustainable Nuclear Industrial Initiative is funding three Generation IV reactor systems, one of which is a lead-cooled fast reactor that is also an [[Subcritical reactor|accelerator-driven sub-critical]] reactor, called ''[[MYRRHA]]'', 100 MW(t), which will be built in [[Belgium]] with construction expected to begin after 2014 and the industrial scale version, known as ''Alfred'', slated to be constructed sometime after 2017. A reduced-power model of Myrrha called ''Guinevere'' was started up at [[Mol, Belgium|Mol]] in March 2009.<ref name="euronuclear.org"/> In 2012 the research team reported that Guinevere was operational.<ref>{{cite news|last1=Hellemans|first1=Alexander|title=Reactor-Accelerator Hybrid Achieves Successful Test Run|url=http://news.sciencemag.org/physics/2012/01/reactor-accelerator-hybrid-achieves-successful-test-run|accessdate=29 December 2014|work=Science Insider|date=12 January 2012}}</ref>

Two other lead-cooled fast reactors under development are the SVBR-100, a modular 100MWe lead-bismuth cooled fast neutron reactor concept designed by OKB [[Gidropress]] in Russia and the BREST-OD-300 (Lead-cooled fast reactor) 300 MWe, to be developed after the SVBR-100, and built over 2016-20, it will dispense with the [[Uranium-238|fertile blanket]] around the core and will supersede the sodium cooled [[BN-600 reactor]] design, to purportedly give enhanced proliferation resistance.<ref name="powertecrussia.com"/>

== Advantages and disadvantages ==
Relative to current nuclear power plant technology, the claimed benefits for 4th generation reactors include:
* Nuclear waste that remains radioactive for a few centuries instead of millennia <ref>{{cite web |title=Strategies to Address Global Warming |url=http://www.columbia.edu/~jeh1/mailings/2009/20090713_Strategies.pdf}}</ref>
* 100-300 times more energy yield from the same amount of nuclear fuel <ref>{{cite web |title=4th Generation Nuclear Power |url=http://www.ossfoundation.us/projects/energy/nuclear}}</ref>
* Broader range of fuels, and even unencapsulated raw fuels (non-pebble [[Molten Salt Reactor|MSR]], [[LFTR]]).
* In some reactors, the ability to consume existing nuclear waste in the production of electricity, that is, a Closed [[nuclear fuel cycle]]. This strengthens the argument to deem [[nuclear power as renewable energy]].
* Improved operating safety features, such as (depending on design) avoidance of pressurized operation, automatic passive (unpowered, uncommanded) reactor shutdown, avoidance of water cooling and the associated risks of loss of water (leaks or boiling) and hydrogen generation/explosion and contamination of coolant water.

Nuclear reactors do not emit CO2 during operation, although like all [[low carbon power]] sources, the mining and construction phase can result in CO2 emissions, if energy sources which are not carbon neutral (such as fossil fuels), or CO2 emitting cements are used during the construction process.
A 2012 [[Yale University]] review published in the Journal of Industrial Ecology analyzing {{CO2}} [[life cycle assessment]] (LCA) emissions from [[nuclear power]] determined that:<ref name="Warner + Heath, JoIE">Warner, Ethan S.; Heath, Garvin A. [http://onlinelibrary.wiley.com/doi/10.1111/j.1530-9290.2012.00472.x/full Life Cycle Greenhouse Gas Emissions of Nuclear Electricity Generation: Systematic Review and Harmonization], ''Journal of Industrial Ecology'', [[Yale University]], published online April 17, 2012, doi: 10.1111/j.1530-9290.2012.00472.x.</ref>
{{Quote|''"The collective LCA literature indicates that life cycle [[Greenhouse gas|GHG]] [ greenhouse gas ] emissions from nuclear power are only a fraction of traditional fossil sources and comparable to renewable technologies."''}}
Although the paper primarily dealt with data from [[Generation II reactor]]s, and did not analyze the {{CO2}} emissions by 2050 of the presently under construction [[Generation III reactor]]s, it did summarize the Life Cycle Assessment findings of in development reactor technologies.''{{Quote|FBRs ''[ [[Fast Breeder Reactor]]s ]'' have been evaluated in the LCA literature. The limited literature that evaluates this potential future technology reports [[median]] life cycle GHG emissions... similar to or lower than LWRs[ Gen II [[light water reactor]]s ] and purports to consume little or no [[uranium market|uranium ore]].}}

A specific risk of the sodium-cooled fast reactor is related to using metallic sodium as a coolant. In case of a breach, sodium explosively reacts with water. Fixing breaches may also prove dangerous, as the cheapest noble gas [[argon]] is also used to prevent sodium oxidation. Argon, like helium, can displace oxygen in the air and can pose [[hypoxia (environmental)|hypoxia]] concerns, so workers may be exposed to this additional risk. This is a pertinent problem as can be testified by the events at the [[LMFBR|loop type]] [[Monju Nuclear Power Plant|Prototype Fast Breeder Reactor Monju]] at Tsuruga, Japan.<ref>{{cite news |title=Japan Strains to Fix a Reactor Damaged Before Quake |url=http://www.nytimes.com/2011/06/18/world/asia/18japan.html | work=The New York Times | first=Hiroko |last=Tabuchi |date=17 June 2011}}</ref>
Using lead or molten salts mitigates this problem by making the coolant less reactive and allowing a high freezing temperature and low pressure in case of a leak. Disadvantages of lead compared to sodium are much higher viscosity, much higher density, lower heat capacity, and more radioactive neutron activation products.

In many cases, there is already a large amount of experience built up with numerous proof of concept Gen IV designs. For example, the reactors at [[Fort St. Vrain Generating Station]] and [[HTR-10]] are similar to the proposed Gen IV [[VHTR]] designs, and the [[LMFBR|pool type]] [[EBR-II]], [[Phénix]] and [[BN-600]] reactor are similar to the proposed pool type Gen IV Sodium Cooled Fast reactors being designed.

== Generation IV International Forum ==
There are currently ten active members of the Generation IV International Forum (GIF): [[Canada]], [[China]], the [[European Atomic Energy Community]] (Euratom), [[France]], [[Japan]], [[Russia]], [[South Africa]], [[South Korea]], [[Switzerland]], and the [[United States]]. The non-active members are [[Argentina]], [[Brazil]], and the [[United Kingdom]].<ref name="gen-4">{{cite web|title=GIF Membership|url=https://www.gen-4.org/gif/jcms/c_9492/members|website=gen-4.org|accessdate=28 October 2014}}</ref>

The Generation IV International Forum (GIF) was founded in 2001. Switzerland joined in 2002, Euratom in 2003, and China and Russia in 2006. The remaining countries were founding members.<ref name="gen-4"/>

The 36th GIF meeting in [[Brussels]] was held in November 2013.<ref>{{cite web |url=http://www.energy.gov/ne/articles/generation-iv-international-forum-updates-technology-roadmap-and-builds-future |title=generation IV international forum updates technology roadmap and builds future. DOE}}</ref><ref>{{cite web |url=http://events.r20.constantcontact.com/register/event?llr=mscrkjkab&oeidk=a07e7melf609716b2c6 |title=The Generation IV international forum holds their 36th meeting on Monday 18th Nov 2013 in Brussels.}}</ref> The ''Technology Roadmap Update for Generation IV Nuclear Energy Systems'' was published in January 2014 which details R&D objectives for the next decade.<ref>[https://web.archive.org/web/20140625102915/https://www.gen-4.org/gif/upload/docs/application/pdf/2014-03/gif-tru2014.pdf Technology Roadmap Update for Generation IV Nuclear Energy Systems]</ref> A breakdown of the reactor designs being researched by each forum member has been made available.<ref>[https://web.archive.org/web/20140708023538/https://www.gen-4.org/gif/upload/docs/application/pdf/2014-03/gif_overview_presentation_v9_final3_web.pdf Generation IV International Forum, overview, John E. Kelly, page 15]</ref>

== See also ==
{{colbegin|3}}
* [[Nuclear reactor]]
* [[Nuclear material]]
* [[Nuclear physics]]
* [[List of reactor types#Reactor types|List of reactor types]]
* [[Generation II reactor]]
* [[Generation III reactor]]
* [[Integral Fast Reactor]]
* [[Liquid fluoride thorium reactor]]
* [[Breeder reactor]]
* [[Small modular reactor]]
{{colend}}

== References ==
{{reflist}}

== External links ==
* [https://inlportal.inl.gov/portal/server.pt?open=514&objID=1361&parentname=CommunityPage&parentid=10&mode=2&in_hi_userid=200&cached=true Article from Idaho National Laboratory detailing some current efforts at developing Gen. IV reactors.]
* [http://www.gen-4.org/ Generation IV International Forum (GIF)]
* [http://nuclear.energy.gov/genIV/neGenIV1.html U.S. Department of Energy Office of Nuclear Energy, Science and Technology]
* [http://www.engr.utk.edu/nuclear/colloquia/slides/Gen%20IV%20U-Tenn%20Presentation.pdf Gen IV presentation]
* [http://www.ecology.at/ecology/files/pr577_1.pdf Science or Fiction - Is there a Future for Nuclear?] (Nov. 2007) - A publication from the Austrian [[Ecology Institute (Austria)|Ecology Institute]] about 'Generation IV' and Fusion reactors.
* {{cite web |url=http://memagazine.asme.org/Articles/2011/December/Nuclear_Power_After_Fukushima.cfm |title=Nuclear Power After Fukushima |author=Gail H. Marcus |date=December 2011 |work=Mechanical Engineering (the magazine of [[ASME]]) |accessdate=23 January 2012}} "In the wake of a severe plant accident, advanced reactor designs are getting renewed attention."
* [http://www.itheo.org/ International Thorium Energy Organisation - www.IThEO.org]
* [http://www.ithec.org/ International Thorium Energy Committee - iThEC]

{{Nuclear fission reactors}}

[[Category:Nuclear power reactor types]]
[[Category:Idaho National Laboratory]]

Benutzer:Snackroeg/Kernreaktoren der Generation 5

2015-08-17T05:48:15Z

Boundarylayer:

[[File:GenIVRoadmap-en.svg|thumb|480px|Nuclear Energy Systems Deployable no later than 2030 and offering significant advances in sustainability, safety and reliability, and economics]]

'''Generation IV reactors''' (Gen IV) are a set of [[nuclear reactor]] designs currently being researched for commercial applications, with depending on the particular design, [[Technology readiness level]]s varying between the level requiring a demonstration, to economical competitive implementation. Most of these designs, with the exception of the [[BN-1200 reactor]], are generally not expected to be available for commercial construction before 2030-40.<ref name="Generation IV">[http://www.world-nuclear.org/info/Nuclear-Fuel-Cycle/Power-Reactors/Generation-IV-Nuclear-Reactors/]</ref> Presently the majority of reactors in operation around the world are generally considered [[Generation II reactor|second generation reactor]] systems, with the vast majority of the [[Generation I reactor|first-generation]] systems having been retired some time ago while there are only a dozen or so [[Generation III reactors]] in operation (2014). [[Nuclear reactor#Generation V+ reactors|Generation V reactors]] refer to reactors that are purely theoretical and are therefore not yet considered feasible in the short term, resulting in limited [[R&D]] funding.

== Reactor types ==
Many reactor types were considered initially; however, the list was downsized to focus on the most promising technologies and those that could most likely meet the goals of the Gen IV initiative.<ref name="Generation IV"/> Three systems are nominally [[thermal reactor]]s and three are [[fast reactor]]s. The Very High Temperature Reactor (VHTR) is also being researched for potentially providing high quality process heat for [[thermochemical cycle|hydrogen production]]. The fast reactors offer the possibility of burning [[actinides]] to further reduce waste and of being able to "[[breeder reactor|breed more fuel]]" than they consume. These systems offer significant advances in sustainability, safety and reliability, economics, proliferation resistance (depending on perspective) and physical protection.

{| class=wikitable
|-
! System
! Neuron Spectrum
! Coolant
! Temperature
! Fuel Cycle
! Size
|-
| VHTR
| Thermal
| Helium
| 900-1000
| Open
| 250-300
|-
| SFR
| Fast
| Sodium
| 550
| Closed
| 30-150, 300-1500, 1000-2000
|-
| SCWR
| Thermal/fast
| Water
| 510-625
| Open/closed
| 300-700, 1000-1500
|-
| GFR
| Fast
| Helium
| 850
| Closed
| 1200
|-
| LFR
| Fast
| Lead
| 480-800
| Closed
| 20-180, 300-1200, 600-1000
|-
| MSR
| Fast/thermal
| Fluoride salts
| 700-800
| Closed
| 1000
|}
<ref>https://www.gen-4.org/gif/upload/docs/application/pdf/2013-09/gif_rd_outlook_for_generation_iv_nuclear_energy_systems.pdf</ref>
=== Thermal reactors ===
A [[Thermal-neutron reactor|thermal reactor]] is a [[nuclear reactor]] that uses slow or [[thermal neutrons]]. A [[neutron moderator]] is used to slow the [[neutron]]s emitted by fission to make them more likely to be captured by the fuel.

==== Very-high-temperature reactor (VHTR) ====
[[File:Very High Temperature Reactor.svg|right|thumb|Very-High-Temperature Reactor (VHTR)]]
{{Main|Very high temperature reactor}}
{{see also|Fort St. Vrain Generating Station|HTTR|HTR-10}}
The '''very high temperature reactor''' concept uses a [[graphite]]-moderated core with a once-through [[uranium]] fuel cycle, using helium or molten salt as the [[Very high temperature reactor#Coolant|coolant]]. This reactor design envisions an outlet temperature of 1,000 °C. The reactor core can be either a prismatic-block or a [[pebble bed reactor]] design. The high temperatures enable applications such as process heat or [[hydrogen]] production via the thermochemical [[Sulfur-iodine cycle|iodine-sulfur]] process. It would also be [[Passive nuclear safety|passively safe]].

The planned construction of the first VHTR, the South African PBMR ([[pebble bed modular reactor]]), lost government funding in February, 2010.<ref>[http://www.powergenworldwide.com/index/display/articledisplay/6322207443/articles/power-engineering-international/volume-18/Issue_3/regulars/world-news/INTERNATIONAL.html South Africa to stop funding Pebble Bed nuclear reactor]</ref> A pronounced increase of costs and concerns about possible unexpected technical problems had discouraged potential investors and customers.

The [[Peoples Republic of China]] began construction of a 200-MWe High Temperature Pebble bed reactor in 2012 as a successor to its [[HTR-10]].<ref>[http://www.nucnet.org/all-the-news/2013/01/07/china-begins-construction-of-first-generation-iv-htr-pm-unit Nucnet Report: 'China Begins Construction of First Generation IV HTR-PM Unit', 7 January 2013]</ref>

Also in 2012, as part of the [[Next Generation Nuclear Plant]] competition, [[Idaho National Laboratory]] approved a design similar to [[Areva]]'s prismatic block [http://de.areva.com/EN/areva-germany-312/future-reactor-concepts.html Antares reactor] as the chosen [[HTGR]] to be deployed as a prototype by 2021. It was in competition with [[General Atomics]]' [[Gas turbine modular helium reactor]] and [[Westinghouse Electric Company|Westinghouse]]'s [[Pebble Bed Modular Reactor]].<ref name="World nuclear news">{{cite web|url=http://www.world-nuclear-news.org/NN-Areva_modular_reactor_selected_for_NGNP_development-1502124.html|title=INL approves Antares design}}</ref>

==== Molten-salt reactor (MSR) ====
[[File:Molten Salt Reactor.svg|right|thumb|Molten Salt Reactor (MSR)]]
{{Main|Molten salt reactor}}
{{see also|Liquid fluoride thorium reactor}}
A '''molten salt reactor'''<ref name="Roadmap"/> is a type of [[nuclear reactor]] where the primary [[coolant]], or even the fuel itself is a molten salt mixture. There have been many designs put forward for this type of reactor and a few prototypes built. The early concepts and many current ones rely on [[nuclear fuel]] dissolved in the molten [[fluoride]] salt as [[uranium tetrafluoride]] (UF4) or [[thorium tetrafluoride]] (ThF4). The fluid would reach [[Nuclear reactor physics#Criticality|criticality]] by flowing into a [[graphite]] core which would also serve as the [[neutron moderator|moderator]]. Many current concepts rely on fuel that is dispersed in a graphite matrix with the molten salt providing low pressure, high temperature cooling.

The Gen IV MSR is more accurately termed an [[epithermal neutron|epithermal reactor]] than a thermal reactor due to the average speed of the neutrons that would cause the fission events within its fuel being faster than [[thermal neutron]]s.<ref>{{cite web |url=https://inlportal.inl.gov/portal/server.pt?open=514&objID=1361&parentname=CommunityPage&parentid=10&mode=2&in_hi_userid=200&cached=true |title=Idaho National Laboratory detailing some current efforts at developing Gen. IV reactors}}</ref>

The principle of a MSR can be used for thermal, epithermal and fast reactors. Since 2005 the focus has moved towards a fast spectrum MSR (MSFR).
<ref>H. Boussier, S. Delpech, V. Ghetta et Al. : The Molten Salt Reactor (MSR) in Generation IV: Overview and Perspectives, GIF SYMPOSIUM PROCEEDINGS/2012 ANNUAL REPORT, NEA No. 7141, pp95 [https://www.gen-4.org/gif/jcms/c_44720/annual-reports]
</ref>

==== Supercritical-water-cooled reactor (SCWR) ====
[[File:Supercritical-Water-Cooled Reactor.svg|right|thumb|Supercritical-Water-Cooled Reactor (SCWR)]]
{{Main|Supercritical water reactor}}
The '''supercritical water reactor''' (SCWR)<ref name="Roadmap"/> is a [[reduced moderation water reactor]] concept that, due to the average speed of the neutrons that would cause the fission events within the fuel being faster than [[thermal neutron]]s, it is more accurately termed an [[epithermal neutron|epithermal reactor]] than a thermal reactor. It uses [[supercritical fluid|supercritical water]] as the working fluid. SCWRs are basically [[light water reactor]]s (LWR) operating at higher pressure and temperatures with a direct, once-through heat exchange cycle. As most commonly envisioned, it would operate on a direct cycle, much like a boiling water reactor ([[BWR]]), but since it uses supercritical water (not to be confused with [[Critical mass (nuclear)|critical mass]]) as the working fluid, it would have only one water phase present, which makes the supercritical heat exchange method more similar to a pressurized water reactor ([[Pressurized water reactor|PWR]]). It could operate at much higher temperatures than both current PWRs and BWRs.

Supercritical water-cooled reactors (SCWRs) are promising advanced nuclear systems because of their high [[thermal efficiency]] (i.e., about 45% vs. about 33% efficiency for current LWRs) and considerable plant simplification.

The main mission of the SCWR is generation of low-cost [[electricity]]. It is built upon two proven technologies, LWRs, which are the most commonly deployed power generating reactors in the world, and superheated [[fossil fuel]] fired [[boiler]]s, a large number of which are also in use around the world. The SCWR concept is being investigated by 32 organizations in 13 countries.{{citation needed|date=October 2012}}

A SCWR Design under development is the [[VVER]]-1700/393 (VVER-SCWR or VVER-SKD) — a Russian Supercritical-water-cooled reactor with double-inlet-core and a [[breeder reactor|breeding ratio]] of 0.95.<ref name="powertecrussia.com">{{cite web |url=http://www.powertecrussia.com/blog/tag/nuclear-power/ |title=Technology Developments & Plant Efficiency for the Russian Nuclear Power Generation Market Wednesday |date=March 24, 2010}}</ref>

=== Fast reactors ===
A [[Fast-neutron reactor|fast reactor]] directly uses the fast neutrons emitted by fission, without moderation. Unlike thermal neutron reactors, fast neutron reactors can be configured to "burn", or fission, all [[actinides]], and given enough time, therefore drastically reduce the actinides fraction in [[spent nuclear fuel]] produced by the present world fleet of thermal neutron [[light water reactor]]s, thus closing the [[nuclear fuel cycle]]. Alternatively, if configured differently, they can also [[breeder reactor|breed]] more actinide fuel than they consume.

==== Gas-cooled fast reactor (GFR) ====
[[File:Gas-Cooled Fast Reactor Schemata.svg|right|thumb|Gas-Cooled Fast Reactor (GFR)]]
{{Main|Gas-cooled fast reactor}}
The '''gas-cooled fast reactor''' (GFR)<ref name="Roadmap"/> system features a fast-neutron spectrum and closed fuel cycle for efficient conversion of [[Fertile material|fertile uranium]] and management of actinides. The reactor is [[helium]]-cooled and with an outlet temperature of 850 °C it is an evolution of the [[very-high-temperature reactor]] (VHTR) to a more sustainable fuel cycle. It will use a direct [[Brayton cycle]] [[Closed-cycle gas turbine|gas turbine]] for high thermal efficiency. Several fuel forms are being considered for their potential to operate at very high temperatures and to ensure an excellent retention of [[Nuclear fission|fission]] products: composite [[ceramic]] fuel, advanced fuel particles, or ceramic clad elements of actinide compounds. Core configurations are being considered based on pin- or plate-based fuel assemblies or prismatic blocks.

The European Sustainable Nuclear Industrial Initiative is funding three Generation IV reactor systems, one of which is a gas-cooled fast reactor, called ''Allegro'', 100 MW(t), which will be built in a central or eastern European country with construction expected to begin in 2018.<ref name="euronuclear.org">{{cite web |url=https://www.euronuclear.org/1-information/news/Gen-IV.htm |title=The European Sustainable Nuclear Industrial Initiative (ESNII) will support three Generation IV reactor systems: a sodium-cooled fast reactor, or SFR, called ''Astrid'' that is proposed by France; a gas-cooled fast reactor, GFR, called ''Allegro'' supported by central and eastern Europe; and a lead-cooled fast reactor, LFR, technology pilot called ''Myrrha'' that is proposed by Belgium.}}</ref> The central European [[Visegrád Group]] are committed to pursuing the technology.<ref>{{cite web |url=http://www.alphagalileo.org/ViewItem.aspx?ItemId=133111&CultureCode=en |title=The V4G4 Centre of Excellence for performing joint research, development and innovation in the field of Generation-4 (G4) nuclear reactors have been established. 20 July 2013 National Center for Nuclear Research (NCBJ]}}</ref> In 2013 German, British, and French institutes finished a 3-year collaboration study on the follow on industrial scale design, known as ''GoFastR''.<ref>{{cite web |url=http://www.ist-world.org/ProjectDetails.aspx?ProjectId=5cb8f3f283574cc6b2bdbf72533172d8 |title=the European Gas cooled Fast Reactor.}}</ref> They were funded by the EU's 7th FWP [[framework programme]], with the goal of making a sustainable VHTR.<ref>{{cite web |url=http://www.2020-horizon.com/GOFASTR-European-Gas-Cooled-Fast-Reactor%28GOFASTR%29-s312.html |title=The GOFASTR research program}}</ref>

==== Sodium-cooled fast reactor (SFR) ====
[[File:Sodium-Cooled Fast Reactor Schemata.svg|right|thumb|Pool design Sodium-Cooled Fast Reactor (SFR)]]
{{Main|Sodium-cooled fast reactor}}
{{see also|Experimental Breeder Reactor II|S-PRISM|BN-800 reactor|Toshiba 4S}}
The SFR<ref name="Roadmap"/> is a project that builds on two closely related existing projects, the liquid metal [[Breeder reactor#Fast breeder reactor|fast breeder reactor]] and the [[integral fast reactor]].

The goals are to increase the efficiency of uranium usage by [[breeder reactor|breeding]] plutonium and eliminating the need for [[transuranic]] isotopes ever to leave the site. The reactor design uses an unmoderated core running on [[fast neutron]]s, designed to allow any transuranic isotope to be consumed (and in some cases used as fuel). In addition to the benefits of removing the long [[half-life]] transuranics from the waste cycle, the SFR fuel expands when the reactor overheats, and the chain reaction automatically slows down. In this manner, it is passively safe.<ref>{{cite web |url=http://www.ne.anl.gov/About/hn/logos-winter02-psr.shtml|title=Passively safe reactors rely on nature to keep them cool|author=David Baurac}}</ref>

The SFR reactor concept is cooled by liquid [[sodium]] and fueled by a metallic alloy of uranium and [[plutonium]] or [[spent nuclear fuel]], the "nuclear waste" of [[light water reactor]]s. The SFR fuel is contained in steel cladding with liquid sodium filling in the space between the clad elements which make up the fuel assembly. One of the design challenges of an SFR is the risks of handling sodium, which reacts explosively if it comes into contact with water. However, the use of liquid metal instead of water as coolant allows the system to work at atmospheric pressure, reducing the risk of leakage.

The European Sustainable Nuclear Industrial Initiative is funding three Generation IV reactor systems, one of which is a sodium-cooled fast reactor, called ''[[ASTRID (reactor)|ASTRID]]'', Advanced Sodium Technical Reactor for Industrial Demonstration, [[Areva]], [[Commissariat à l'énergie atomique et aux énergies alternatives|CEA]] and [[Électricité de France|EDF]] are leading the design with British collaboration.<ref>{{cite web |url=http://www.power-eng.com/articles/2010/11/areva--cea-secure.html |title=Areva, CEA secure EUR650m funding to develop ASTRID sodium-cooled Generation IV reactor 11/11/2010}}</ref><ref>{{cite web |url=http://www.powermag.com/uk-and-france-sign-landmark-civil-nuclear-cooperation-agreement/ |title=UK and France Sign Landmark Civil Nuclear Cooperation Agreement 02/22/2012 . POWERnews}}</ref> Astrid will be rated about 600 MWe and is proposed to be built in France, near to the [[Phénix]] reactor. A final decision in construction is to be made in 2019<ref name="euronuclear.org"/>

The [[China|PRC]]'s first commercial-scale, 800 MWe, fast neutron reactor, to be situated near [[Sanming]] in [[Fujian province]] will be a SFR. In 2009 an agreement was signed that would entail the Russian [[BN-800 reactor]] design to be sold to the PRC once it is completed, this would be the first time commercial-scale fast neutron reactors have ever been exported.<ref>{{cite web |url=http://www.world-nuclear-news.org/C-Joint_venture_launched_for_Chinese_fast_reactor-3004104.html |title=Joint venture launched for Chinese fast reactor}}</ref> The BN-800 reactor became operational in 2014.

In India, the [[Prototype Fast Breeder Reactor]], a 500MWe Sodium cooled fast reactor is being built at a cost of INR 5,677 crores (~US$900 million) and is expected to be commissioned by September 2016. The PFBR will be followed by six more Commercial Fast Breeder Reactors (CFBRs) of 500 MWe each.

The 400MWe [[Fast Flux Test Facility]] operated successfully for ten years at the Hanford site in Washington State.

The 20 MWe [[EBR II]] operated successfully for over thirty years at the Idaho National Laboratory, until it was shut down in 1994.

==== Lead-cooled fast reactor (LFR) ====
[[File:Lead-Cooled Fast Reactor Schemata.svg|right|thumb|Lead-Cooled Fast Reactor (LFR)]]
{{Main|Lead-cooled fast reactor}}
{{See also|MYRRHA}}
The '''lead-cooled fast reactor'''<ref name="Roadmap">{{cite journal| year=2002 | title=A Technology Roadmap for Generation IV Nuclear Energy Systems | last=US DOE Nuclear Energy Research Advisory Committee |volume=GIF-002-00|url=http://nuclear.energy.gov/genIV/documents/gen_iv_roadmap.pdf}}</ref> features a fast-neutron-spectrum [[lead]] or [[lead]]/[[bismuth]] [[eutectic]] ([[Lead-bismuth eutectic|LBE]]) liquid-metal-cooled reactor with a closed [[Nuclear fuel cycle|fuel cycle]]. Options include a range of plant ratings, including a "battery" of 50 to 150 MW of electricity that features a very long refueling interval, a modular system rated at 300 to 400 MW, and a large monolithic plant option at 1,200 MW. (The term ''battery'' refers to the long-life, factory-fabricated core, not to any provision for electrochemical energy conversion.) The fuel is metal or nitride-based containing [[Fertile material|fertile uranium]] and [[transuranic]]s. The LFR is cooled by natural [[convection]] with a reactor outlet coolant temperature of 550 °C, possibly ranging up to 800 °C with advanced materials. The higher temperature enables the production of [[Thermochemical cycle|hydrogen by thermochemical processes]].

The European Sustainable Nuclear Industrial Initiative is funding three Generation IV reactor systems, one of which is a lead-cooled fast reactor that is also an [[Subcritical reactor|accelerator-driven sub-critical]] reactor, called ''[[MYRRHA]]'', 100 MW(t), which will be built in [[Belgium]] with construction expected to begin after 2014 and the industrial scale version, known as ''Alfred'', slated to be constructed sometime after 2017. A reduced-power model of Myrrha called ''Guinevere'' was started up at [[Mol, Belgium|Mol]] in March 2009.<ref name="euronuclear.org"/> In 2012 the research team reported that Guinevere was operational.<ref>{{cite news|last1=Hellemans|first1=Alexander|title=Reactor-Accelerator Hybrid Achieves Successful Test Run|url=http://news.sciencemag.org/physics/2012/01/reactor-accelerator-hybrid-achieves-successful-test-run|accessdate=29 December 2014|work=Science Insider|date=12 January 2012}}</ref>

Two other lead-cooled fast reactors under development are the SVBR-100, a modular 100MWe lead-bismuth cooled fast neutron reactor concept designed by OKB [[Gidropress]] in Russia and the BREST-OD-300 (Lead-cooled fast reactor) 300 MWe, to be developed after the SVBR-100, and built over 2016-20, it will dispense with the [[Uranium-238|fertile blanket]] around the core and will supersede the sodium cooled [[BN-600 reactor]] design, to purportedly give enhanced proliferation resistance.<ref name="powertecrussia.com"/>

== Advantages and disadvantages ==
Relative to current nuclear power plant technology, the claimed benefits for 4th generation reactors include:
* Nuclear waste that remains radioactive for a few centuries instead of millennia <ref>{{cite web |title=Strategies to Address Global Warming |url=http://www.columbia.edu/~jeh1/mailings/2009/20090713_Strategies.pdf}}</ref>
* 100-300 times more energy yield from the same amount of nuclear fuel <ref>{{cite web |title=4th Generation Nuclear Power |url=http://www.ossfoundation.us/projects/energy/nuclear}}</ref>
* Broader range of fuels, and even unencapsulated raw fuels (non-pebble [[Molten Salt Reactor|MSR]], [[LFTR]]).
* In some reactors, the ability to consume existing nuclear waste in the production of electricity, that is, a Closed [[nuclear fuel cycle]]. This strengthens the argument to deem [[nuclear power as renewable energy]].
* Improved operating safety features, such as (depending on design) avoidance of pressurized operation, automatic passive (unpowered, uncommanded) reactor shutdown, avoidance of water cooling and the associated risks of loss of water (leaks or boiling) and hydrogen generation/explosion and contamination of coolant water.

Nuclear reactors do not emit CO2 during operation, although like all [[low carbon power]] sources, the mining and construction phase can result in CO2 emissions, if energy sources which are not carbon neutral (such as fossil fuels), or CO2 emitting cements are used during the construction process.
A 2012 [[Yale University]] review published in the Journal of Industrial Ecology analyzing {{CO2}} [[life cycle assessment]] (LCA) emissions from [[nuclear power]] determined that:<ref name="Warner + Heath, JoIE">Warner, Ethan S.; Heath, Garvin A. [http://onlinelibrary.wiley.com/doi/10.1111/j.1530-9290.2012.00472.x/full Life Cycle Greenhouse Gas Emissions of Nuclear Electricity Generation: Systematic Review and Harmonization], ''Journal of Industrial Ecology'', [[Yale University]], published online April 17, 2012, doi: 10.1111/j.1530-9290.2012.00472.x.</ref>
{{Quote|''"The collective LCA literature indicates that life cycle [[Greenhouse gas|GHG]] [ greenhouse gas ] emissions from nuclear power are only a fraction of traditional fossil sources and comparable to renewable technologies."''}}
Although the paper primarily dealt with data from [[Generation II reactor]]s, and did not analyze the {{CO2}} emissions by 2050 of the presently under construction [[Generation III reactor]]s, it did summarize the Life Cycle Assessment findings of in development reactor technologies.''{{Quote|FBRs ''[ [[Fast Breeder Reactor]]s ]'' have been evaluated in the LCA literature. The limited literature that evaluates this potential future technology reports [[median]] life cycle GHG emissions... similar to or lower than LWRs[ Gen II [[light water reactor]]s ] and purports to consume little or no [[uranium market|uranium ore]].}}

A specific risk of the sodium-cooled fast reactor is related to using metallic sodium as a coolant. In case of a breach, sodium explosively reacts with water. Fixing breaches may also prove dangerous, as the cheapest noble gas [[argon]] is also used to prevent sodium oxidation. Argon, like helium, can displace oxygen in the air and can pose [[hypoxia (environmental)|hypoxia]] concerns, so workers may be exposed to this additional risk. This is a pertinent problem as can be testified by the events at the [[LMFBR|loop type]] [[Monju Nuclear Power Plant|Prototype Fast Breeder Reactor Monju]] at Tsuruga, Japan.<ref>{{cite news |title=Japan Strains to Fix a Reactor Damaged Before Quake |url=http://www.nytimes.com/2011/06/18/world/asia/18japan.html | work=The New York Times | first=Hiroko |last=Tabuchi |date=17 June 2011}}</ref>
Using lead or molten salts mitigates this problem by making the coolant less reactive and allowing a high freezing temperature and low pressure in case of a leak. Disadvantages of lead compared to sodium are much higher viscosity, much higher density, lower heat capacity, and more radioactive neutron activation products.

In many cases, there is already a large amount of experience built up with numerous proof of concept Gen IV designs. For example, the reactors at [[Fort St. Vrain Generating Station]] and [[HTR-10]] are similar to the proposed Gen IV [[VHTR]] designs, and the [[LMFBR|pool type]] [[EBR-II]], [[Phénix]] and [[BN-600]] reactor are similar to the proposed pool type Gen IV Sodium Cooled Fast reactors being designed.

== Generation IV International Forum ==
There are currently ten active members of the Generation IV International Forum (GIF): [[Canada]], [[China]], the [[European Atomic Energy Community]] (Euratom), [[France]], [[Japan]], [[Russia]], [[South Africa]], [[South Korea]], [[Switzerland]], and the [[United States]]. The non-active members are [[Argentina]], [[Brazil]], and the [[United Kingdom]].<ref name="gen-4">{{cite web|title=GIF Membership|url=https://www.gen-4.org/gif/jcms/c_9492/members|website=gen-4.org|accessdate=28 October 2014}}</ref>

The Generation IV International Forum (GIF) was founded in 2001. Switzerland joined in 2002, Euratom in 2003, and China and Russia in 2006. The remaining countries were founding members.<ref name="gen-4"/>

The 36th GIF meeting in [[Brussels]] was held in November 2013.<ref>{{cite web |url=http://www.energy.gov/ne/articles/generation-iv-international-forum-updates-technology-roadmap-and-builds-future |title=generation IV international forum updates technology roadmap and builds future. DOE}}</ref><ref>{{cite web |url=http://events.r20.constantcontact.com/register/event?llr=mscrkjkab&oeidk=a07e7melf609716b2c6 |title=The Generation IV international forum holds their 36th meeting on Monday 18th Nov 2013 in Brussels.}}</ref> The ''Technology Roadmap Update for Generation IV Nuclear Energy Systems'' was published in January 2014 which details R&D objectives for the next decade.<ref>[https://web.archive.org/web/20140625102915/https://www.gen-4.org/gif/upload/docs/application/pdf/2014-03/gif-tru2014.pdf Technology Roadmap Update for Generation IV Nuclear Energy Systems]</ref> A breakdown of the reactor designs being researched by each forum member has been made available.<ref>[https://web.archive.org/web/20140708023538/https://www.gen-4.org/gif/upload/docs/application/pdf/2014-03/gif_overview_presentation_v9_final3_web.pdf Generation IV International Forum, overview, John E. Kelly, page 15]</ref>

== See also ==
{{colbegin|3}}
* [[Nuclear reactor]]
* [[Nuclear material]]
* [[Nuclear physics]]
* [[List of reactor types#Reactor types|List of reactor types]]
* [[Generation II reactor]]
* [[Generation III reactor]]
* [[Integral Fast Reactor]]
* [[Liquid fluoride thorium reactor]]
* [[Breeder reactor]]
* [[Small modular reactor]]
{{colend}}

== References ==
{{reflist}}

== External links ==
* [https://inlportal.inl.gov/portal/server.pt?open=514&objID=1361&parentname=CommunityPage&parentid=10&mode=2&in_hi_userid=200&cached=true Article from Idaho National Laboratory detailing some current efforts at developing Gen. IV reactors.]
* [http://www.gen-4.org/ Generation IV International Forum (GIF)]
* [http://nuclear.energy.gov/genIV/neGenIV1.html U.S. Department of Energy Office of Nuclear Energy, Science and Technology]
* [http://www.engr.utk.edu/nuclear/colloquia/slides/Gen%20IV%20U-Tenn%20Presentation.pdf Gen IV presentation]
* [http://www.ecology.at/ecology/files/pr577_1.pdf Science or Fiction - Is there a Future for Nuclear?] (Nov. 2007) - A publication from the Austrian [[Ecology Institute (Austria)|Ecology Institute]] about 'Generation IV' and Fusion reactors.
* {{cite web |url=http://memagazine.asme.org/Articles/2011/December/Nuclear_Power_After_Fukushima.cfm |title=Nuclear Power After Fukushima |author=Gail H. Marcus |date=December 2011 |work=Mechanical Engineering (the magazine of [[ASME]]) |accessdate=23 January 2012}} "In the wake of a severe plant accident, advanced reactor designs are getting renewed attention."
* [http://www.itheo.org/ International Thorium Energy Organisation - www.IThEO.org]
* [http://www.ithec.org/ International Thorium Energy Committee - iThEC]

{{Nuclear fission reactors}}

[[Category:Nuclear power reactor types]]
[[Category:Idaho National Laboratory]]

Benutzer:Snackroeg/Kernreaktoren der Generation 5

2014-10-23T00:48:00Z

Boundarylayer: /* Advantages and disadvantages */ red link fix, sentence ce

[[File:GenIVRoadmap.jpg|right|480px|Nuclear Energy Systems Deployable no later than 2030 and offering significant advances in sustainability, safety and reliability, and economics]]
'''Generation IV reactors''' (Gen IV) are a set of mostly theoretical nuclear reactor designs currently being researched. Most of these designs, with the exception of the [[BN-1200 reactor]], are generally not expected to be available for commercial construction before 2030.<ref name="Generation IV">[http://www.euronuclear.org/1-information/generation-IV.htm Generation IV]</ref> Most reactors in operation around the world are generally considered [[Generation II reactor|second generation reactor]] systems, with most of the [[Generation I reactor|first-generation]] systems having been retired some time ago while there are only a dozen or so [[Generation III reactors]] in operation(2014). [[Nuclear reactor#Generation V.2B reactors|Generation V reactors]] refer to reactors that may be possible but are not yet considered feasible in the short term, and are therefore not receiving as much [[R&D]] funding.

== Reactor types ==
Many reactor types were considered initially; however, the list was downsized to focus on the most promising technologies and those that could most likely meet the goals of the Gen IV initiative.<ref name="Generation IV"/> Three systems are nominally [[thermal reactor]]s and three are [[fast reactor]]s. The Very High Temperature Reactor (VHTR) is also being researched for potentially providing high quality process heat for [[thermochemical cycle|hydrogen production]]. The fast reactors offer the possibility of burning [[actinides]] to further reduce waste and of being able to "[[breeder reactor|breed more fuel]]" than they consume. These systems offer significant advances in sustainability, safety and reliability, economics, proliferation resistance (depending on perspective) and physical protection.

=== Thermal reactors ===
A [[Thermal-neutron reactor|thermal reactor]] is a [[nuclear reactor]] that uses slow or [[thermal neutrons]]. A [[neutron moderator]] is used to slow the [[neutron]]s emitted by fission to make them more likely to be captured by the fuel.

==== Very-high-temperature reactor (VHTR) ====
[[File:Very High Temperature Reactor.svg|right|thumb|Very-High-Temperature Reactor (VHTR)]]
{{Main|Very high temperature reactor}}
{{see also|Fort St. Vrain Generating Station|HTTR|HTR-10}}
The '''very high temperature reactor''' concept uses a [[graphite]]-moderated core with a once-through [[uranium]] fuel cycle, using helium or molten salt as the [[Very high temperature reactor#Coolant|coolant]]. This reactor design envisions an outlet temperature of 1,000 °C. The reactor core can be either a prismatic-block or a [[pebble bed reactor]] design. The high temperatures enable applications such as process heat or [[hydrogen]] production via the thermochemical [[Sulfur-iodine cycle|iodine-sulfur]] process. It would also be [[Passive nuclear safety|passively safe]].

The planned construction of the first VHTR, the South African PBMR ([[pebble bed modular reactor]]), lost government funding in February, 2010.<ref>[http://www.powergenworldwide.com/index/display/articledisplay/6322207443/articles/power-engineering-international/volume-18/Issue_3/regulars/world-news/INTERNATIONAL.html South Africa to stop funding Pebble Bed nuclear reactor]</ref> A pronounced increase of costs and concerns about possible unexpected technical problems had discouraged potential investors and customers.

The [[Peoples Republic of China]] began construction of a 200-MWe High Temperature Pebble bed reactor in 2012 as a successor to its [[HTR-10]].<ref>[http://www.nucnet.org/all-the-news/2013/01/07/china-begins-construction-of-first-generation-iv-htr-pm-unit Nucnet Report: 'China Begins Construction of First Generation IV HTR-PM Unit', 7 January 2013]</ref>

Also in 2012, as part of the [[Next Generation Nuclear Plant]] competition, [[Idaho National Laboratory]] approved a design similar to [[Areva]]'s prismatic block [http://de.areva.com/EN/areva-germany-312/future-reactor-concepts.html Antares reactor] as the chosen [[HTGR]] to be deployed as a prototype by 2021. It was in competition with [[General Atomics]]' [[Gas turbine modular helium reactor]] and [[Westinghouse Electric Company|Westinghouse]]'s [[Pebble Bed Modular Reactor]].<ref name="World nuclear news">{{cite web|url=http://www.world-nuclear-news.org/NN-Areva_modular_reactor_selected_for_NGNP_development-1502124.html|title=INL approves Antares design}}</ref>

==== Molten-salt reactor (MSR) ====
[[File:Molten Salt Reactor.svg|right|thumb|Molten Salt Reactor (MSR)]]
{{Main|Molten salt reactor}}
{{see also|Liquid fluoride thorium reactor}}
A '''molten salt reactor'''<ref name="Roadmap"/> is a type of [[nuclear reactor]] where the primary [[coolant]], or even the fuel itself is a molten salt mixture. There have been many designs put forward for this type of reactor and a few prototypes built. The early concepts and many current ones rely on [[nuclear fuel]] dissolved in the molten [[fluoride]] salt as [[uranium tetrafluoride]] (UF4) or [[thorium tetrafluoride]] (ThF4). The fluid would reach [[Nuclear reactor physics#Criticality|criticality]] by flowing into a [[graphite]] core which would also serve as the [[neutron moderator|moderator]]. Many current concepts rely on fuel that is dispersed in a graphite matrix with the molten salt providing low pressure, high temperature cooling.

The Gen IV MSR is more accurately termed an [[epithermal neutron|epithermal reactor]] than a thermal reactor due to the average speed of the neutrons that would cause the fission events within its fuel being faster than [[thermal neutron]]s.<ref>{{cite web |url=https://inlportal.inl.gov/portal/server.pt?open=514&objID=1361&parentname=CommunityPage&parentid=10&mode=2&in_hi_userid=200&cached=true |title=Idaho National Laboratory detailing some current efforts at developing Gen. IV reactors}}</ref>

The principle of a MSR can be used for thermal, epithermal and fast reactors. Since 2005 the focus has moved towards a fast spectrum MSR (MSFR).
<ref>H. Boussier, S. Delpech, V. Ghetta et Al. : The Molten Salt Reactor (MSR) in Generation IV: Overview and Perspectives, GIF SYMPOSIUM PROCEEDINGS/2012 ANNUAL REPORT, NEA No. 7141, pp95 [https://www.gen-4.org/gif/jcms/c_44720/annual-reports]
</ref>

==== Supercritical-water-cooled reactor (SCWR) ====
[[File:Supercritical-Water-Cooled Reactor.svg|right|thumb|Supercritical-Water-Cooled Reactor (SCWR)]]
{{Main|Supercritical water reactor}}
The '''supercritical water reactor''' (SCWR)<ref name="Roadmap"/> is a [[reduced moderation water reactor]] concept that, due to the average speed of the neutrons that would cause the fission events within the fuel being faster than [[thermal neutron]]s, it is more accurately termed an [[epithermal neutron|epithermal reactor]] than a thermal reactor. It uses [[supercritical fluid|supercritical water]] as the working fluid. SCWRs are basically [[light water reactor]]s (LWR) operating at higher pressure and temperatures with a direct, once-through heat exchange cycle. As most commonly envisioned, it would operate on a direct cycle, much like a boiling water reactor ([[BWR]]), but since it uses supercritical water (not to be confused with [[Critical mass (nuclear)|critical mass]]) as the working fluid, it would have only one water phase present, which makes the supercritical heat exchange method more similar to a pressurized water reactor ([[Pressurized water reactor|PWR]]). It could operate at much higher temperatures than both current PWRs and BWRs.

Supercritical water-cooled reactors (SCWRs) are promising advanced nuclear systems because of their high [[thermal efficiency]] (i.e., about 45% vs. about 33% efficiency for current LWRs) and considerable plant simplification.

The main mission of the SCWR is generation of low-cost [[electricity]]. It is built upon two proven technologies, LWRs, which are the most commonly deployed power generating reactors in the world, and supercritical [[fossil fuel]] fired [[boiler]]s, a large number of which are also in use around the world. The SCWR concept is being investigated by 32 organizations in 13 countries.{{citation needed|date=October 2012}}

A SCWR Design under development is the [[VVER]]-1700/393 (VVER-SCWR or VVER-SKD) — a Russian Supercritical-water-cooled reactor with double-inlet-core and a [[breeder reactor|breeding ratio]] of 0.95.<ref name="powertecrussia.com">{{cite web |url=http://www.powertecrussia.com/blog/tag/nuclear-power/ |title=Technology Developments & Plant Efficiency for the Russian Nuclear Power Generation Market Wednesday |date=March 24, 2010}}</ref>

=== Fast reactors ===
A [[Fast-neutron reactor|fast reactor]] directly uses the fast neutrons emitted by fission, without moderation. Unlike thermal neutron reactors, fast neutron reactors can be configured to "burn", or fission, all [[actinides]], and given enough time, therefore drastically reduce the actinides fraction in [[spent nuclear fuel]] produced by the present world fleet of thermal neutron [[Light Water Reactor]]s, thus closing the [[Nuclear fuel cycle]]. Alternatively, if configured differently, they can also [[breeder reactor|breed]] more actinide fuel than they consume.

==== Gas-cooled fast reactor (GFR) ====
[[File:Gas-Cooled Fast Reactor Schemata.svg|right|thumb|Gas-Cooled Fast Reactor (GFR)]]
{{Main|Gas-cooled fast reactor}}
The '''gas-cooled fast reactor''' (GFR)<ref name="Roadmap"/> system features a fast-neutron spectrum and closed [[Nuclear fuel cycle|fuel cycle]] for efficient conversion of [[Fertile material|fertile uranium]] and management of [[actinide]]s. The reactor is [[helium]]-cooled and with an outlet temperature of 850 °C it is an evolution of the [[Very High Temperature Reactor]](VHTR) to a more sustainable fuel cycle. It will use a direct [[Brayton cycle]] [[Closed-cycle gas turbine|gas turbine]] for high thermal efficiency. Several fuel forms are being considered for their potential to operate at very high temperatures and to ensure an excellent retention of [[Nuclear fission|fission]] products: composite [[ceramic]] fuel, advanced fuel particles, or ceramic clad elements of actinide compounds. Core configurations are being considered based on pin- or plate-based fuel assemblies or prismatic blocks.

The European Sustainable Nuclear Industrial Initiative is funding three Generation IV reactor systems, one of which is a gas-cooled fast reactor, called ''Allegro'', 100 MW(t), which will be built in a central or eastern European country with construction expected to begin in 2018.<ref name="euronuclear.org">{{cite web |url=https://www.euronuclear.org/1-information/news/Gen-IV.htm |title=The European Sustainable Nuclear Industrial Initiative (ESNII) will support three Generation IV reactor systems: a sodium-cooled fast reactor, or SFR, called ''Astrid'' that is proposed by France; a gas-cooled fast reactor, GFR, called ''Allegro'' supported by central and eastern Europe; and a lead-cooled fast reactor, LFR, technology pilot called ''Myrrha'' that is proposed by Belgium.}}</ref> The central European [[Visegrád Group]] are committed to pursuing the technology.<ref>{{cite web |url=http://www.alphagalileo.org/ViewItem.aspx?ItemId=133111&CultureCode=en |title=The V4G4 Centre of Excellence for performing joint research, development and innovation in the field of Generation-4 (G4) nuclear reactors have been established. 20 July 2013 National Center for Nuclear Research (NCBJ]}}</ref> In 2013 German, British, and French institutes finished a 3 year collaboration study on the follow on industrial scale design, known as ''GoFastR''.<ref>{{cite web |url=http://www.ist-world.org/ProjectDetails.aspx?ProjectId=5cb8f3f283574cc6b2bdbf72533172d8 |title=the European Gas cooled Fast Reactor.}}</ref> They were funded by the EU's 7th FWP framework programme, with the goal of making a sustainable [[VHTR]].<ref>{{cite web |url=http://www.2020-horizon.com/GOFASTR-European-Gas-Cooled-Fast-Reactor%28GOFASTR%29-s312.html |title=The GOFASTR research program}}</ref>

==== Sodium-cooled fast reactor (SFR) ====
[[File:Sodium-Cooled Fast Reactor Schemata.svg|right|thumb|Pool design Sodium-Cooled Fast Reactor (SFR)]]
{{Main|Sodium-cooled fast reactor}}
{{see also|Experimental Breeder Reactor II|S-PRISM|BN-800 reactor|Toshiba 4S}}
The SFR<ref name="Roadmap"/> is a project that builds on two closely related existing projects, the [[LMFBR|liquid metal fast breeder reactor]] and the [[Integral Fast Reactor]].

The goals are to increase the efficiency of uranium usage by [[breeder reactor|breeding]] plutonium and eliminating the need for [[transuranic]] isotopes ever to leave the site. The reactor design uses an unmoderated core running on [[fast neutron]]s, designed to allow any transuranic isotope to be consumed (and in some cases used as fuel). In addition to the benefits of removing the long [[half-life]] transuranics from the waste cycle, the SFR fuel expands when the reactor overheats, and the chain reaction automatically slows down. In this manner, it is passively safe.

The SFR reactor concept is cooled by liquid [[sodium]] and fueled by a metallic alloy of [[uranium]] and [[plutonium]] or [[spent nuclear fuel]], the "nuclear waste" of [[Light Water Reactor]]s. The SFR fuel is contained in steel cladding with liquid sodium filling in the space between the clad elements which make up the fuel assembly. One of the design challenges of an SFR is the risks of handling sodium, which reacts explosively if it comes into contact with water. However, the use of liquid metal instead of water as coolant allows the system to work at atmospheric pressure, reducing the risk of leakage.

The European Sustainable Nuclear Industrial Initiative is funding three Generation IV reactor systems, one of which is a sodium-cooled fast reactor, called ''ASTRID'', Advanced Sodium Technical Reactor for Industrial Demonstration, [[Areva]], [[Commissariat à l'énergie atomique et aux énergies alternatives|CEA]] and [[Électricité de France|EDF]] are leading the design with British collaboration.<ref>{{cite web |url=http://www.power-eng.com/articles/2010/11/areva--cea-secure.html |title=Areva, CEA secure EUR650m funding to develop ASTRID sodium-cooled Generation IV reactor 11/11/2010}}</ref><ref>{{cite web |url=http://www.powermag.com/uk-and-france-sign-landmark-civil-nuclear-cooperation-agreement/ |title=UK and France Sign Landmark Civil Nuclear Cooperation Agreement 02/22/2012 . POWERnews}}</ref> Astrid will be rated about 600 MWe and is expected to be built in France, with construction slated to begin in 2017 near to the [[Phénix]] reactor.<ref name="euronuclear.org"/>

The [[PRC]]'s first commercial-scale, 800 MWe, fast neutron reactor, to be situated near Sanming city in [[Fujian province]] will be a SFR. In 2009 an agreement was signed that would entail the Russian [[BN-800 reactor]] design to be sold to the PRC once it is completed, this would be the first time commercial-scale fast neutron reactors have ever been exported.<ref>{{cite web |url=http://www.world-nuclear-news.org/C-Joint_venture_launched_for_Chinese_fast_reactor-3004104.html |title=Joint venture launched for Chinese fast reactor}}</ref> The [[BN-800 reactor]] became operational in 2014.

In India, the [[Prototype Fast Breeder Reactor]], a 500MWe Sodium cooled fast reactor is under construction, with a completion year of 2014/2015.

==== Lead-cooled fast reactor (LFR) ====
[[File:Lead-Cooled Fast Reactor Schemata.svg|right|thumb|Lead-Cooled Fast Reactor (LFR)]]
{{Main|Lead-cooled fast reactor}}
{{See also|MYRRHA|BREST-300}}
The '''lead-cooled fast reactor'''<ref name="Roadmap">{{cite journal| year=2002 | title=A Technology Roadmap for Generation IV Nuclear Energy Systems | last=US DOE Nuclear Energy Research Advisory Committee |volume=GIF-002-00|url=http://nuclear.energy.gov/genIV/documents/gen_iv_roadmap.pdf}}</ref> features a fast-neutron-spectrum [[lead]] or [[lead]]/[[bismuth]] [[eutectic]] ([[Lead-bismuth eutectic|LBE]]) liquid-metal-cooled reactor with a closed [[Nuclear fuel cycle|fuel cycle]]. Options include a range of plant ratings, including a "battery" of 50 to 150 MW of electricity that features a very long refueling interval, a modular system rated at 300 to 400 MW, and a large monolithic plant option at 1,200 MW. (The term ''battery'' refers to the long-life, factory-fabricated core, not to any provision for electrochemical energy conversion.) The fuel is metal or nitride-based containing [[Fertile material|fertile uranium]] and [[transuranic]]s. The LFR is cooled by natural [[convection]] with a reactor outlet coolant temperature of 550 °C, possibly ranging up to 800 °C with advanced materials. The higher temperature enables the production of [[Thermochemical cycle|hydrogen by thermochemical processes]].

The European Sustainable Nuclear Industrial Initiative is funding three Generation IV reactor systems, one of which is a lead-cooled fast reactor that is also an [[Accelerator-driven system|Accelerator-driven sub-critical]] reactor, called ''Myrrha'', 100 MW(t), which will be built in [[Belgium]] with construction expected to begin after 2014 and the industrial scale version, known as ''Alfred'', slated to be constructed sometime after 2017. A reduced-power model of Myrrha called ''Guinevere'' was started up at [[Mol, Belgium|Mol]] in March 2009.<ref name="euronuclear.org"/>

Two other lead-cooled fast reactors under development are the SVBR-100, a modular 100MWe lead-bismuth cooled fast neutron reactor concept designed by OKB [[Gidropress]] in Russia and the BREST-OD-300 (Lead-cooled fast reactor) 300 MWe, to be developed after the SVBR-100, and built over 2016-20, it will dispense with the [[Uranium-238|fertile blanket]] around the core and will supersede the sodium cooled [[BN-600 reactor]] design, to purportedly give enhanced proliferation resistance.<ref name="powertecrussia.com"/>

== Advantages and disadvantages==
Relative to current nuclear power plant technology, the claimed benefits for 4th generation reactors include:
* Nuclear waste that remains radioactive for a few centuries instead of millennia <ref>{{cite web |title=Strategies to Address Global Warming |url=http://www.columbia.edu/~jeh1/mailings/2009/20090713_Strategies.pdf}}</ref>
* 100-300 times more energy yield from the same amount of nuclear fuel <ref>{{cite web |title=4th Generation Nuclear Power |url=http://www.ossfoundation.us/projects/energy/nuclear}}</ref>
* The ability to consume existing nuclear waste in the production of electricity, that is, a Closed [[nuclear fuel cycle]]. This strengthens the argument to deem [[nuclear power as renewable energy]].
* Improved operating safety

Nuclear reactors do not emit CO2 during operation, although like all [[low carbon power]] sources, the mining and construction phase can result in CO2 emissions, if energy sources which are not carbon neutral (such as fossil fuels), or CO2 emitting cements are used during the construction process.
A 2012 [[Yale University]] review published in the Journal of Industrial Ecology analyzing {{CO2}} [[life cycle assessment]] (LCA) emissions from [[nuclear power]] determined that:<ref name="Warner + Heath, JoIE">Warner, Ethan S.; Heath, Garvin A. [http://onlinelibrary.wiley.com/doi/10.1111/j.1530-9290.2012.00472.x/full Life Cycle Greenhouse Gas Emissions of Nuclear Electricity Generation: Systematic Review and Harmonization], ''Journal of Industrial Ecology'', [[Yale University]], published online April 17, 2012, doi: 10.1111/j.1530-9290.2012.00472.x.</ref>
{{Quote|''"The collective LCA literature indicates that life cycle [[Greenhouse gas|GHG]] [ greenhouse gas ] emissions from nuclear power are only a fraction of traditional fossil sources and comparable to renewable technologies."''}}
Although the paper primarily dealt with data from [[Generation II reactor]]s, and did not analyze the {{CO2}} emissions by 2050 of the presently under construction [[Generation III reactor]]s, it did summarize the Life Cycle Assessment findings of in development reactor technologies.''{{Quote|FBRs ''[ [[Fast Breeder Reactor]]s ]'' have been evaluated in the LCA literature. The limited literature that evaluates this potential future technology reports [[median]] life cycle GHG emissions... similar to or lower than LWRs[ Gen II [[light water reactor]]s ] and purports to consume little or no [[uranium market|uranium ore]].}}

A specific risk of the sodium-cooled fast reactor is related to using metallic sodium as a coolant. In case of a breach, sodium explosively reacts with water. Fixing breaches may also prove dangerous, as the cheapest noble gas [[argon]] is also used to prevent sodium oxidation. Argon, like helium, can displace oxygen in the air and can pose [[hypoxia (environmental)|hypoxia]] concerns, so workers may be exposed to this additional risk. This is a pertinent problem as can be testified by the events at the [[LMFBR|loop type]] [[Monju Nuclear Power Plant|Prototype Fast Breeder Reactor Monju]] at Tsuruga, Japan.<ref>{{cite news |title=Japan Strains to Fix a Reactor Damaged Before Quake |url=http://www.nytimes.com/2011/06/18/world/asia/18japan.html | work=The New York Times | first=Hiroko |last=Tabuchi |date=17 June 2011}}</ref>
Using lead or molten salts mitigates this problem by making the coolant less reactive and allowing a high freezing temperature and low pressure in case of a leak.

In many cases, there is already a large amount of experience built up with numerous proof of concept Gen IV designs. For example, the reactors at [[Fort St. Vrain Generating Station]] and [[HTR-10]] are similar to the proposed Gen IV [[VHTR]] designs, and the [[LMFBR|pool type]] [[EBR-II]], [[Phénix]] and [[BN-600]] reactor are similar to the proposed pool type Gen IV Sodium Cooled Fast reactors being designed.

== Participating countries ==
The members of the Generation IV International Forum (GIF) are:
* {{ARG}} [http://www.cnea.gov.ar/] (Spanish-only web site)
* {{BRA}} [http://www.aben.com.br/]
* {{CAN}} [http://www.aecl.ca/]
* {{CHN}} [http://www.caea.gov.cn/n602669/n2231600/n2272156/n2272415/167948.html]
* {{EU}} [http://www.euronuclear.org/1-information/generation-IV.htm]
* {{FRA}} [http://www.cea.fr/]
* {{JPN}} [http://www.jaea.go.jp/english/]
* {{KOR}} [http://www.mest.go.kr/index.html] (Korean-only web site)
* {{RUS}} [http://www.rosatom.ru/en/]
* {{RSA}} [http://www.eskom.co.za/live/index.php]
* {{SUI}} [http://www.psi.ch/index_e.shtml]
* {{UK}} [http://www.dti.gov.uk/energy/sources/nuclear/technology/fission/page17924.html]
* {{USA}} [http://nuclear.energy.gov/genIV/neGenIV1.html]

The nine GIF founding members were joined by Switzerland in 2002, Euratom in 2003 and most recently by China and Russia at the end of 2006.<ref>{{cite web | author=[[Commissariat à l'Énergie Atomique]]|title= Future nuclear systems| url=http://nucleaire.cea.fr/fr/nucleaire_futur/pu_schema1ch2.htm}}</ref>

Australia has also shown interest in joining the GIF.{{citation needed|date=March 2012}}

The 36th GIF meeting in [[Brussels]] was held in November 2013.<ref>{{cite web |url=http://events.r20.constantcontact.com/register/event?llr=mscrkjkab&oeidk=a07e7melf609716b2c6 |title=The Generation IV international forum holds their 36th meeting on Monday 18th Nov 2013 in Brussels.}}</ref>

==See also==
{{colbegin|3}}
* [[Nuclear reactor]]
* [[Nuclear material]]
* [[Nuclear physics]]
* [[List of reactor types#Reactor types|List of reactor types]]
* [[Generation II reactor]]
* [[Generation III reactor]]
* [[Integral Fast Reactor]]
* [[Liquid fluoride thorium reactor]]
* [[Breeder reactor]]
* [[Small modular reactor]]
{{colend}}

==References==
{{reflist}}

== External links ==
* [https://inlportal.inl.gov/portal/server.pt?open=514&objID=1361&parentname=CommunityPage&parentid=10&mode=2&in_hi_userid=200&cached=true Article from Idaho National Laboratory detailing some current efforts at developing Gen. IV reactors.]
* [http://www.gen-4.org/ Generation IV International Forum (GIF)]
* [http://nuclear.energy.gov/genIV/neGenIV1.html U.S. Department of Energy Office of Nuclear Energy, Science and Technology]
* [http://www.engr.utk.edu/nuclear/colloquia/slides/Gen%20IV%20U-Tenn%20Presentation.pdf Gen IV presentation]
* [http://www.ecology.at/ecology/files/pr577_1.pdf Science or Fiction - Is there a Future for Nuclear?] (Nov. 2007) - A publication from the Austrian [[Ecology Institute (Austria)|Ecology Institute]] about 'Generation IV' and Fusion reactors.
* {{cite web |url=http://memagazine.asme.org/Articles/2011/December/Nuclear_Power_After_Fukushima.cfm |title=Nuclear Power After Fukushima |author=Gail H. Marcus |date=December 2011 |work=Mechanical Engineering (the magazine of [[ASME]]) |accessdate=23 January 2012}} "In the wake of a severe plant accident, advanced reactor designs are getting renewed attention."
*[http://www.itheo.org/ International Thorium Energy Organisation - www.IThEO.org]
*[http://www.ithec.org/ International Thorium Energy Committee - iThEC]

{{Nuclear fission reactors}}

[[Category:Nuclear power reactor types]]
[[Category:Idaho National Laboratory]]

Benutzer:Snackroeg/Kernreaktoren der Generation 5

2014-10-22T06:28:38Z

Boundarylayer: The BN-800 reactor is close to but not a true gen IV design, the russian's know this and have only planned to submit the 1200 design to Gen IV certification

[[File:GenIVRoadmap.jpg|right|480px|Nuclear Energy Systems Deployable no later than 2030 and offering significant advances in sustainability, safety and reliability, and economics]]
'''Generation IV reactors''' (Gen IV) are a set of mostly theoretical nuclear reactor designs currently being researched. Most of these designs, with the exception of the [[BN-1200 reactor]], are generally not expected to be available for commercial construction before 2030.<ref name="Generation IV">[http://www.euronuclear.org/1-information/generation-IV.htm Generation IV]</ref> Most reactors in operation around the world are generally considered [[Generation II reactor|second generation reactor]] systems, with most of the [[Generation I reactor|first-generation]] systems having been retired some time ago while there are only a dozen or so [[Generation III reactors]] in operation(2014). [[Nuclear reactor#Generation V.2B reactors|Generation V reactors]] refer to reactors that may be possible but are not yet considered feasible in the short term, and are therefore not receiving as much [[R&D]] funding.

== Reactor types ==
Many reactor types were considered initially; however, the list was downsized to focus on the most promising technologies and those that could most likely meet the goals of the Gen IV initiative.<ref name="Generation IV"/> Three systems are nominally [[thermal reactor]]s and three are [[fast reactor]]s. The Very High Temperature Reactor (VHTR) is also being researched for potentially providing high quality process heat for [[thermochemical cycle|hydrogen production]]. The fast reactors offer the possibility of burning [[actinides]] to further reduce waste and of being able to "[[breeder reactor|breed more fuel]]" than they consume. These systems offer significant advances in sustainability, safety and reliability, economics, proliferation resistance (depending on perspective) and physical protection.

=== Thermal reactors ===
A [[Thermal-neutron reactor|thermal reactor]] is a [[nuclear reactor]] that uses slow or [[thermal neutrons]]. A [[neutron moderator]] is used to slow the [[neutron]]s emitted by fission to make them more likely to be captured by the fuel.

==== Very-high-temperature reactor (VHTR) ====
[[File:Very High Temperature Reactor.svg|right|thumb|Very-High-Temperature Reactor (VHTR)]]
{{Main|Very high temperature reactor}}
{{see also|Fort St. Vrain Generating Station|HTTR|HTR-10}}
The '''very high temperature reactor''' concept uses a [[graphite]]-moderated core with a once-through [[uranium]] fuel cycle, using helium or molten salt as the [[Very high temperature reactor#Coolant|coolant]]. This reactor design envisions an outlet temperature of 1,000 °C. The reactor core can be either a prismatic-block or a [[pebble bed reactor]] design. The high temperatures enable applications such as process heat or [[hydrogen]] production via the thermochemical [[Sulfur-iodine cycle|iodine-sulfur]] process. It would also be [[Passive nuclear safety|passively safe]].

The planned construction of the first VHTR, the South African PBMR ([[pebble bed modular reactor]]), lost government funding in February, 2010.<ref>[http://www.powergenworldwide.com/index/display/articledisplay/6322207443/articles/power-engineering-international/volume-18/Issue_3/regulars/world-news/INTERNATIONAL.html South Africa to stop funding Pebble Bed nuclear reactor]</ref> A pronounced increase of costs and concerns about possible unexpected technical problems had discouraged potential investors and customers.

The [[Peoples Republic of China]] began construction of a 200-MWe High Temperature Pebble bed reactor in 2012 as a successor to its [[HTR-10]].<ref>[http://www.nucnet.org/all-the-news/2013/01/07/china-begins-construction-of-first-generation-iv-htr-pm-unit Nucnet Report: 'China Begins Construction of First Generation IV HTR-PM Unit', 7 January 2013]</ref>

Also in 2012, as part of the [[Next Generation Nuclear Plant]] competition, [[Idaho National Laboratory]] approved a design similar to [[Areva]]'s prismatic block [http://de.areva.com/EN/areva-germany-312/future-reactor-concepts.html Antares reactor] as the chosen [[HTGR]] to be deployed as a prototype by 2021. It was in competition with [[General Atomics]]' [[Gas turbine modular helium reactor]] and [[Westinghouse Electric Company|Westinghouse]]'s [[Pebble Bed Modular Reactor]].<ref name="World nuclear news">{{cite web|url=http://www.world-nuclear-news.org/NN-Areva_modular_reactor_selected_for_NGNP_development-1502124.html|title=INL approves Antares design}}</ref>

==== Molten-salt reactor (MSR) ====
[[File:Molten Salt Reactor.svg|right|thumb|Molten Salt Reactor (MSR)]]
{{Main|Molten salt reactor}}
{{see also|Liquid fluoride thorium reactor}}
A '''molten salt reactor'''<ref name="Roadmap"/> is a type of [[nuclear reactor]] where the primary [[coolant]], or even the fuel itself is a molten salt mixture. There have been many designs put forward for this type of reactor and a few prototypes built. The early concepts and many current ones rely on [[nuclear fuel]] dissolved in the molten [[fluoride]] salt as [[uranium tetrafluoride]] (UF4) or [[thorium tetrafluoride]] (ThF4). The fluid would reach [[Nuclear reactor physics#Criticality|criticality]] by flowing into a [[graphite]] core which would also serve as the [[neutron moderator|moderator]]. Many current concepts rely on fuel that is dispersed in a graphite matrix with the molten salt providing low pressure, high temperature cooling.

The Gen IV MSR is more accurately termed an [[epithermal neutron|epithermal reactor]] than a thermal reactor due to the average speed of the neutrons that would cause the fission events within its fuel being faster than [[thermal neutron]]s.<ref>{{cite web |url=https://inlportal.inl.gov/portal/server.pt?open=514&objID=1361&parentname=CommunityPage&parentid=10&mode=2&in_hi_userid=200&cached=true |title=Idaho National Laboratory detailing some current efforts at developing Gen. IV reactors}}</ref>

The principle of a MSR can be used for thermal, epithermal and fast reactors. Since 2005 the focus has moved towards a fast spectrum MSR (MSFR).
<ref>H. Boussier, S. Delpech, V. Ghetta et Al. : The Molten Salt Reactor (MSR) in Generation IV: Overview and Perspectives, GIF SYMPOSIUM PROCEEDINGS/2012 ANNUAL REPORT, NEA No. 7141, pp95 [https://www.gen-4.org/gif/jcms/c_44720/annual-reports]
</ref>

==== Supercritical-water-cooled reactor (SCWR) ====
[[File:Supercritical-Water-Cooled Reactor.svg|right|thumb|Supercritical-Water-Cooled Reactor (SCWR)]]
{{Main|Supercritical water reactor}}
The '''supercritical water reactor''' (SCWR)<ref name="Roadmap"/> is a [[reduced moderation water reactor]] concept that, due to the average speed of the neutrons that would cause the fission events within the fuel being faster than [[thermal neutron]]s, it is more accurately termed an [[epithermal neutron|epithermal reactor]] than a thermal reactor. It uses [[supercritical fluid|supercritical water]] as the working fluid. SCWRs are basically [[light water reactor]]s (LWR) operating at higher pressure and temperatures with a direct, once-through heat exchange cycle. As most commonly envisioned, it would operate on a direct cycle, much like a boiling water reactor ([[BWR]]), but since it uses supercritical water (not to be confused with [[Critical mass (nuclear)|critical mass]]) as the working fluid, it would have only one water phase present, which makes the supercritical heat exchange method more similar to a pressurized water reactor ([[Pressurized water reactor|PWR]]). It could operate at much higher temperatures than both current PWRs and BWRs.

Supercritical water-cooled reactors (SCWRs) are promising advanced nuclear systems because of their high [[thermal efficiency]] (i.e., about 45% vs. about 33% efficiency for current LWRs) and considerable plant simplification.

The main mission of the SCWR is generation of low-cost [[electricity]]. It is built upon two proven technologies, LWRs, which are the most commonly deployed power generating reactors in the world, and supercritical [[fossil fuel]] fired [[boiler]]s, a large number of which are also in use around the world. The SCWR concept is being investigated by 32 organizations in 13 countries.{{citation needed|date=October 2012}}

A SCWR Design under development is the [[VVER]]-1700/393 (VVER-SCWR or VVER-SKD) — a Russian Supercritical-water-cooled reactor with double-inlet-core and a [[breeder reactor|breeding ratio]] of 0.95.<ref name="powertecrussia.com">{{cite web |url=http://www.powertecrussia.com/blog/tag/nuclear-power/ |title=Technology Developments & Plant Efficiency for the Russian Nuclear Power Generation Market Wednesday |date=March 24, 2010}}</ref>

=== Fast reactors ===
A [[Fast-neutron reactor|fast reactor]] directly uses the fast neutrons emitted by fission, without moderation. Unlike thermal neutron reactors, fast neutron reactors can be configured to "burn", or fission, all [[actinides]], and given enough time, therefore drastically reduce the actinides fraction in [[spent nuclear fuel]] produced by the present world fleet of thermal neutron [[Light Water Reactor]]s, thus closing the [[Nuclear fuel cycle]]. Alternatively, if configured differently, they can also [[breeder reactor|breed]] more actinide fuel than they consume.

==== Gas-cooled fast reactor (GFR) ====
[[File:Gas-Cooled Fast Reactor Schemata.svg|right|thumb|Gas-Cooled Fast Reactor (GFR)]]
{{Main|Gas-cooled fast reactor}}
The '''gas-cooled fast reactor''' (GFR)<ref name="Roadmap"/> system features a fast-neutron spectrum and closed [[Nuclear fuel cycle|fuel cycle]] for efficient conversion of [[Fertile material|fertile uranium]] and management of [[actinide]]s. The reactor is [[helium]]-cooled and with an outlet temperature of 850 °C it is an evolution of the [[Very High Temperature Reactor]](VHTR) to a more sustainable fuel cycle. It will use a direct [[Brayton cycle]] [[Closed-cycle gas turbine|gas turbine]] for high thermal efficiency. Several fuel forms are being considered for their potential to operate at very high temperatures and to ensure an excellent retention of [[Nuclear fission|fission]] products: composite [[ceramic]] fuel, advanced fuel particles, or ceramic clad elements of actinide compounds. Core configurations are being considered based on pin- or plate-based fuel assemblies or prismatic blocks.

The European Sustainable Nuclear Industrial Initiative is funding three Generation IV reactor systems, one of which is a gas-cooled fast reactor, called ''Allegro'', 100 MW(t), which will be built in a central or eastern European country with construction expected to begin in 2018.<ref name="euronuclear.org">{{cite web |url=https://www.euronuclear.org/1-information/news/Gen-IV.htm |title=The European Sustainable Nuclear Industrial Initiative (ESNII) will support three Generation IV reactor systems: a sodium-cooled fast reactor, or SFR, called ''Astrid'' that is proposed by France; a gas-cooled fast reactor, GFR, called ''Allegro'' supported by central and eastern Europe; and a lead-cooled fast reactor, LFR, technology pilot called ''Myrrha'' that is proposed by Belgium.}}</ref> The central European [[Visegrád Group]] are committed to pursuing the technology.<ref>{{cite web |url=http://www.alphagalileo.org/ViewItem.aspx?ItemId=133111&CultureCode=en |title=The V4G4 Centre of Excellence for performing joint research, development and innovation in the field of Generation-4 (G4) nuclear reactors have been established. 20 July 2013 National Center for Nuclear Research (NCBJ]}}</ref> In 2013 German, British, and French institutes finished a 3 year collaboration study on the follow on industrial scale design, known as ''GoFastR''.<ref>{{cite web |url=http://www.ist-world.org/ProjectDetails.aspx?ProjectId=5cb8f3f283574cc6b2bdbf72533172d8 |title=the European Gas cooled Fast Reactor.}}</ref> They were funded by the EU's 7th FWP framework programme, with the goal of making a sustainable [[VHTR]].<ref>{{cite web |url=http://www.2020-horizon.com/GOFASTR-European-Gas-Cooled-Fast-Reactor%28GOFASTR%29-s312.html |title=The GOFASTR research program}}</ref>

==== Sodium-cooled fast reactor (SFR) ====
[[File:Sodium-Cooled Fast Reactor Schemata.svg|right|thumb|Pool design Sodium-Cooled Fast Reactor (SFR)]]
{{Main|Sodium-cooled fast reactor}}
{{see also|Experimental Breeder Reactor II|S-PRISM|BN-800 reactor|Toshiba 4S}}
The SFR<ref name="Roadmap"/> is a project that builds on two closely related existing projects, the [[LMFBR|liquid metal fast breeder reactor]] and the [[Integral Fast Reactor]].

The goals are to increase the efficiency of uranium usage by [[breeder reactor|breeding]] plutonium and eliminating the need for [[transuranic]] isotopes ever to leave the site. The reactor design uses an unmoderated core running on [[fast neutron]]s, designed to allow any transuranic isotope to be consumed (and in some cases used as fuel). In addition to the benefits of removing the long [[half-life]] transuranics from the waste cycle, the SFR fuel expands when the reactor overheats, and the chain reaction automatically slows down. In this manner, it is passively safe.

The SFR reactor concept is cooled by liquid [[sodium]] and fueled by a metallic alloy of [[uranium]] and [[plutonium]] or [[spent nuclear fuel]], the "nuclear waste" of [[Light Water Reactor]]s. The SFR fuel is contained in steel cladding with liquid sodium filling in the space between the clad elements which make up the fuel assembly. One of the design challenges of an SFR is the risks of handling sodium, which reacts explosively if it comes into contact with water. However, the use of liquid metal instead of water as coolant allows the system to work at atmospheric pressure, reducing the risk of leakage.

The European Sustainable Nuclear Industrial Initiative is funding three Generation IV reactor systems, one of which is a sodium-cooled fast reactor, called ''ASTRID'', Advanced Sodium Technical Reactor for Industrial Demonstration, [[Areva]], [[Commissariat à l'énergie atomique et aux énergies alternatives|CEA]] and [[Électricité de France|EDF]] are leading the design with British collaboration.<ref>{{cite web |url=http://www.power-eng.com/articles/2010/11/areva--cea-secure.html |title=Areva, CEA secure EUR650m funding to develop ASTRID sodium-cooled Generation IV reactor 11/11/2010}}</ref><ref>{{cite web |url=http://www.powermag.com/uk-and-france-sign-landmark-civil-nuclear-cooperation-agreement/ |title=UK and France Sign Landmark Civil Nuclear Cooperation Agreement 02/22/2012 . POWERnews}}</ref> Astrid will be rated about 600 MWe and is expected to be built in France, with construction slated to begin in 2017 near to the [[Phénix]] reactor.<ref name="euronuclear.org"/>

The [[PRC]]'s first commercial-scale, 800 MWe, fast neutron reactor, to be situated near Sanming city in [[Fujian province]] will be a SFR. In 2009 an agreement was signed that would entail the Russian [[BN-800 reactor]] design to be sold to the PRC once it is completed, this would be the first time commercial-scale fast neutron reactors have ever been exported.<ref>{{cite web |url=http://www.world-nuclear-news.org/C-Joint_venture_launched_for_Chinese_fast_reactor-3004104.html |title=Joint venture launched for Chinese fast reactor}}</ref> The [[BN-800 reactor]] became operational in 2014.

In India, the [[Prototype Fast Breeder Reactor]], a 500MWe Sodium cooled fast reactor is under construction, with a completion year of 2014/2015.

==== Lead-cooled fast reactor (LFR) ====
[[File:Lead-Cooled Fast Reactor Schemata.svg|right|thumb|Lead-Cooled Fast Reactor (LFR)]]
{{Main|Lead-cooled fast reactor}}
{{See also|MYRRHA|BREST-300}}
The '''lead-cooled fast reactor'''<ref name="Roadmap">{{cite journal| year=2002 | title=A Technology Roadmap for Generation IV Nuclear Energy Systems | last=US DOE Nuclear Energy Research Advisory Committee |volume=GIF-002-00|url=http://nuclear.energy.gov/genIV/documents/gen_iv_roadmap.pdf}}</ref> features a fast-neutron-spectrum [[lead]] or [[lead]]/[[bismuth]] [[eutectic]] ([[Lead-bismuth eutectic|LBE]]) liquid-metal-cooled reactor with a closed [[Nuclear fuel cycle|fuel cycle]]. Options include a range of plant ratings, including a "battery" of 50 to 150 MW of electricity that features a very long refueling interval, a modular system rated at 300 to 400 MW, and a large monolithic plant option at 1,200 MW. (The term ''battery'' refers to the long-life, factory-fabricated core, not to any provision for electrochemical energy conversion.) The fuel is metal or nitride-based containing [[Fertile material|fertile uranium]] and [[transuranic]]s. The LFR is cooled by natural [[convection]] with a reactor outlet coolant temperature of 550 °C, possibly ranging up to 800 °C with advanced materials. The higher temperature enables the production of [[Thermochemical cycle|hydrogen by thermochemical processes]].

The European Sustainable Nuclear Industrial Initiative is funding three Generation IV reactor systems, one of which is a lead-cooled fast reactor that is also an [[Accelerator-driven system|Accelerator-driven sub-critical]] reactor, called ''Myrrha'', 100 MW(t), which will be built in [[Belgium]] with construction expected to begin after 2014 and the industrial scale version, known as ''Alfred'', slated to be constructed sometime after 2017. A reduced-power model of Myrrha called ''Guinevere'' was started up at [[Mol, Belgium|Mol]] in March 2009.<ref name="euronuclear.org"/>

Two other lead-cooled fast reactors under development are the SVBR-100, a modular 100MWe lead-bismuth cooled fast neutron reactor concept designed by OKB [[Gidropress]] in Russia and the BREST-OD-300 (Lead-cooled fast reactor) 300 MWe, to be developed after the SVBR-100, and built over 2016-20, it will dispense with the [[Uranium-238|fertile blanket]] around the core and will supersede the sodium cooled [[BN-600 reactor]] design, to purportedly give enhanced proliferation resistance.<ref name="powertecrussia.com"/>

== Advantages and disadvantages==
Relative to current nuclear power plant technology, the claimed benefits for 4th generation reactors include:
* Nuclear waste that remains radioactive for a few centuries instead of millennia <ref>{{cite web |title=Strategies to Address Global Warming |url=http://www.columbia.edu/~jeh1/mailings/2009/20090713_Strategies.pdf}}</ref>
* 100-300 times more energy yield from the same amount of nuclear fuel <ref>{{cite web |title=4th Generation Nuclear Power |url=http://www.ossfoundation.us/projects/energy/nuclear}}</ref>
* The ability to consume existing nuclear waste in the production of electricity, that is, a [[closed nuclear fuel cycle]]. This strengthens the arguments for [[nuclear power as renewable energy]].
* Improved operating safety

Nuclear reactors do not emit CO2 during operation, although like all [[low carbon power]] sources, the mining and construction phase can result in CO2 emissions, if energy sources which are not carbon neutral (such as fossil fuels), or CO2 emitting cements are used during the construction process.
A 2012 [[Yale University]] review published in the Journal of Industrial Ecology analyzing {{CO2}} [[life cycle assessment]] (LCA) emissions from [[nuclear power]] determined that:<ref name="Warner + Heath, JoIE">Warner, Ethan S.; Heath, Garvin A. [http://onlinelibrary.wiley.com/doi/10.1111/j.1530-9290.2012.00472.x/full Life Cycle Greenhouse Gas Emissions of Nuclear Electricity Generation: Systematic Review and Harmonization], ''Journal of Industrial Ecology'', [[Yale University]], published online April 17, 2012, doi: 10.1111/j.1530-9290.2012.00472.x.</ref>
{{Quote|''"The collective LCA literature indicates that life cycle [[Greenhouse gas|GHG]] [ greenhouse gas ] emissions from nuclear power are only a fraction of traditional fossil sources and comparable to renewable technologies."''}}
Although the paper primarily dealt with data from [[Generation II reactor]]s, and did not analyze the {{CO2}} emissions by 2050 of the presently under construction [[Generation III reactor]]s, it did summarize the Life Cycle Assessment findings of in development reactor technologies.''{{Quote|FBRs ''[ [[Fast Breeder Reactor]]s ]'' have been evaluated in the LCA literature. The limited literature that evaluates this potential future technology reports [[median]] life cycle GHG emissions... similar to or lower than LWRs[ Gen II [[light water reactor]]s ] and purports to consume little or no [[uranium market|uranium ore]].}}

A specific risk of the sodium-cooled fast reactor is related to using metallic sodium as a coolant. In case of a breach, sodium explosively reacts with water. Fixing breaches may also prove dangerous, as the cheapest noble gas [[argon]] is also used to prevent sodium oxidation. Argon, like helium, can displace oxygen in the air and can pose [[hypoxia (environmental)|hypoxia]] concerns, so workers may be exposed to this additional risk. This is a pertinent problem as can be testified by the events at the [[LMFBR|loop type]] [[Monju Nuclear Power Plant|Prototype Fast Breeder Reactor Monju]] at Tsuruga, Japan.<ref>{{cite news |title=Japan Strains to Fix a Reactor Damaged Before Quake |url=http://www.nytimes.com/2011/06/18/world/asia/18japan.html | work=The New York Times | first=Hiroko |last=Tabuchi |date=17 June 2011}}</ref>
Using lead or molten salts mitigates this problem by making the coolant less reactive and allowing a high freezing temperature and low pressure in case of a leak.

In many cases, there is already a large amount of experience built up with numerous proof of concept Gen IV designs. For example, the reactors at [[Fort St. Vrain Generating Station]] and [[HTR-10]] are similar to the proposed Gen IV [[VHTR]] designs, and the [[LMFBR|pool type]] [[EBR-II]], [[Phénix]] and [[BN-600]] reactor are similar to the proposed pool type Gen IV Sodium Cooled Fast reactors being designed.

== Participating countries ==
The members of the Generation IV International Forum (GIF) are:
* {{ARG}} [http://www.cnea.gov.ar/] (Spanish-only web site)
* {{BRA}} [http://www.aben.com.br/]
* {{CAN}} [http://www.aecl.ca/]
* {{CHN}} [http://www.caea.gov.cn/n602669/n2231600/n2272156/n2272415/167948.html]
* {{EU}} [http://www.euronuclear.org/1-information/generation-IV.htm]
* {{FRA}} [http://www.cea.fr/]
* {{JPN}} [http://www.jaea.go.jp/english/]
* {{KOR}} [http://www.mest.go.kr/index.html] (Korean-only web site)
* {{RUS}} [http://www.rosatom.ru/en/]
* {{RSA}} [http://www.eskom.co.za/live/index.php]
* {{SUI}} [http://www.psi.ch/index_e.shtml]
* {{UK}} [http://www.dti.gov.uk/energy/sources/nuclear/technology/fission/page17924.html]
* {{USA}} [http://nuclear.energy.gov/genIV/neGenIV1.html]

The nine GIF founding members were joined by Switzerland in 2002, Euratom in 2003 and most recently by China and Russia at the end of 2006.<ref>{{cite web | author=[[Commissariat à l'Énergie Atomique]]|title= Future nuclear systems| url=http://nucleaire.cea.fr/fr/nucleaire_futur/pu_schema1ch2.htm}}</ref>

Australia has also shown interest in joining the GIF.{{citation needed|date=March 2012}}

The 36th GIF meeting in [[Brussels]] was held in November 2013.<ref>{{cite web |url=http://events.r20.constantcontact.com/register/event?llr=mscrkjkab&oeidk=a07e7melf609716b2c6 |title=The Generation IV international forum holds their 36th meeting on Monday 18th Nov 2013 in Brussels.}}</ref>

==See also==
{{colbegin|3}}
* [[Nuclear reactor]]
* [[Nuclear material]]
* [[Nuclear physics]]
* [[List of reactor types#Reactor types|List of reactor types]]
* [[Generation II reactor]]
* [[Generation III reactor]]
* [[Integral Fast Reactor]]
* [[Liquid fluoride thorium reactor]]
* [[Breeder reactor]]
* [[Small modular reactor]]
{{colend}}

==References==
{{reflist}}

== External links ==
* [https://inlportal.inl.gov/portal/server.pt?open=514&objID=1361&parentname=CommunityPage&parentid=10&mode=2&in_hi_userid=200&cached=true Article from Idaho National Laboratory detailing some current efforts at developing Gen. IV reactors.]
* [http://www.gen-4.org/ Generation IV International Forum (GIF)]
* [http://nuclear.energy.gov/genIV/neGenIV1.html U.S. Department of Energy Office of Nuclear Energy, Science and Technology]
* [http://www.engr.utk.edu/nuclear/colloquia/slides/Gen%20IV%20U-Tenn%20Presentation.pdf Gen IV presentation]
* [http://www.ecology.at/ecology/files/pr577_1.pdf Science or Fiction - Is there a Future for Nuclear?] (Nov. 2007) - A publication from the Austrian [[Ecology Institute (Austria)|Ecology Institute]] about 'Generation IV' and Fusion reactors.
* {{cite web |url=http://memagazine.asme.org/Articles/2011/December/Nuclear_Power_After_Fukushima.cfm |title=Nuclear Power After Fukushima |author=Gail H. Marcus |date=December 2011 |work=Mechanical Engineering (the magazine of [[ASME]]) |accessdate=23 January 2012}} "In the wake of a severe plant accident, advanced reactor designs are getting renewed attention."
*[http://www.itheo.org/ International Thorium Energy Organisation - www.IThEO.org]
*[http://www.ithec.org/ International Thorium Energy Committee - iThEC]

{{Nuclear fission reactors}}

[[Category:Nuclear power reactor types]]
[[Category:Idaho National Laboratory]]

Benutzer:Snackroeg/Kernreaktoren der Generation 5

2014-10-11T23:08:18Z

Boundarylayer: /* Advantages and disadvantages */Added interlinks renewable energy

[[File:GenIVRoadmap.jpg|right|480px|Nuclear Energy Systems Deployable no later than 2030 and offering significant advances in sustainability, safety and reliability, and economics]]
'''Generation IV reactors''' (Gen IV) are a set of mostly theoretical nuclear reactor designs currently being researched. Most of these designs, with the exception of the [[BN-800 reactor]], are generally not expected to be available for commercial construction before 2030.<ref name="Generation IV">[http://www.euronuclear.org/1-information/generation-IV.htm Generation IV]</ref> Most reactors in operation around the world are generally considered [[Generation II reactor|second generation reactor]] systems, with most of the [[Generation I reactor|first-generation]] systems having been retired some time ago while there are only a dozen or so [[Generation III reactors]] in operation(2014). [[Nuclear reactor#Generation V.2B reactors|Generation V reactors]] refer to reactors that may be possible but are not yet considered feasible in the short term, and are therefore not receiving as much [[R&D]] funding.

== Reactor types ==
Many reactor types were considered initially; however, the list was downsized to focus on the most promising technologies and those that could most likely meet the goals of the Gen IV initiative.<ref name="Generation IV"/> Three systems are nominally [[thermal reactor]]s and three are [[fast reactor]]s. The Very High Temperature Reactor (VHTR) is also being researched for potentially providing high quality process heat for [[thermochemical cycle|hydrogen production]]. The fast reactors offer the possibility of burning [[actinides]] to further reduce waste and of being able to "[[breeder reactor|breed more fuel]]" than they consume. These systems offer significant advances in sustainability, safety and reliability, economics, proliferation resistance (depending on perspective) and physical protection.

=== Thermal reactors ===
A [[Thermal-neutron reactor|thermal reactor]] is a [[nuclear reactor]] that uses slow or [[thermal neutrons]]. A [[neutron moderator]] is used to slow the [[neutron]]s emitted by fission to make them more likely to be captured by the fuel.

==== Very-high-temperature reactor (VHTR) ====
[[File:Very High Temperature Reactor.svg|right|thumb|Very-High-Temperature Reactor (VHTR)]]
{{Main|Very high temperature reactor}}
{{see also|Fort St. Vrain Generating Station|HTTR|HTR-10}}
The '''very high temperature reactor''' concept uses a [[graphite]]-moderated core with a once-through [[uranium]] fuel cycle, using helium or molten salt as the [[Very high temperature reactor#Coolant|coolant]]. This reactor design envisions an outlet temperature of 1,000 °C. The reactor core can be either a prismatic-block or a [[pebble bed reactor]] design. The high temperatures enable applications such as process heat or [[hydrogen]] production via the thermochemical [[Sulfur-iodine cycle|iodine-sulfur]] process. It would also be [[Passive nuclear safety|passively safe]].

The planned construction of the first VHTR, the South African PBMR ([[pebble bed modular reactor]]), lost government funding in February, 2010.<ref>[http://www.powergenworldwide.com/index/display/articledisplay/6322207443/articles/power-engineering-international/volume-18/Issue_3/regulars/world-news/INTERNATIONAL.html South Africa to stop funding Pebble Bed nuclear reactor]</ref> A pronounced increase of costs and concerns about possible unexpected technical problems had discouraged potential investors and customers.

The [[Peoples Republic of China]] began construction of a 200-MWe High Temperature Pebble bed reactor in 2012 as a successor to its [[HTR-10]].<ref>[http://www.nucnet.org/all-the-news/2013/01/07/china-begins-construction-of-first-generation-iv-htr-pm-unit Nucnet Report: 'China Begins Construction of First Generation IV HTR-PM Unit', 7 January 2013]</ref>

Also in 2012, as part of the [[Next Generation Nuclear Plant]] competition, [[Idaho National Laboratory]] approved a design similar to [[Areva]]'s prismatic block [http://de.areva.com/EN/areva-germany-312/future-reactor-concepts.html Antares reactor] as the chosen [[HTGR]] to be deployed as a prototype by 2021. It was in competition with [[General Atomics]]' [[Gas turbine modular helium reactor]] and [[Westinghouse Electric Company|Westinghouse]]'s [[Pebble Bed Modular Reactor]].<ref name="World nuclear news">{{cite web|url=http://www.world-nuclear-news.org/NN-Areva_modular_reactor_selected_for_NGNP_development-1502124.html|title=INL approves Antares design}}</ref>

==== Molten-salt reactor (MSR) ====
[[File:Molten Salt Reactor.svg|right|thumb|Molten Salt Reactor (MSR)]]
{{Main|Molten salt reactor}}
{{see also|Liquid fluoride thorium reactor}}
A '''molten salt reactor'''<ref name="Roadmap"/> is a type of [[nuclear reactor]] where the primary [[coolant]], or even the fuel itself is a molten salt mixture. There have been many designs put forward for this type of reactor and a few prototypes built. The early concepts and many current ones rely on [[nuclear fuel]] dissolved in the molten [[fluoride]] salt as [[uranium tetrafluoride]] (UF4) or [[thorium tetrafluoride]] (ThF4). The fluid would reach [[Nuclear reactor physics#Criticality|criticality]] by flowing into a [[graphite]] core which would also serve as the [[neutron moderator|moderator]]. Many current concepts rely on fuel that is dispersed in a graphite matrix with the molten salt providing low pressure, high temperature cooling.

The Gen IV MSR is more accurately termed an [[epithermal neutron|epithermal reactor]] than a thermal reactor due to the average speed of the neutrons that would cause the fission events within its fuel being faster than [[thermal neutron]]s.<ref>{{cite web |url=https://inlportal.inl.gov/portal/server.pt?open=514&objID=1361&parentname=CommunityPage&parentid=10&mode=2&in_hi_userid=200&cached=true |title=Idaho National Laboratory detailing some current efforts at developing Gen. IV reactors}}</ref>

The principle of a MSR can be used for thermal, epithermal and fast reactors. Since 2005 the focus has moved towards a fast spectrum MSR (MSFR).
<ref>H. Boussier, S. Delpech, V. Ghetta et Al. : The Molten Salt Reactor (MSR) in Generation IV: Overview and Perspectives, GIF SYMPOSIUM PROCEEDINGS/2012 ANNUAL REPORT, NEA No. 7141, pp95 [https://www.gen-4.org/gif/jcms/c_44720/annual-reports]
</ref>

==== Supercritical-water-cooled reactor (SCWR) ====
[[File:Supercritical-Water-Cooled Reactor.svg|right|thumb|Supercritical-Water-Cooled Reactor (SCWR)]]
{{Main|Supercritical water reactor}}
The '''supercritical water reactor''' (SCWR)<ref name="Roadmap"/> is a [[reduced moderation water reactor]] concept that, due to the average speed of the neutrons that would cause the fission events within the fuel being faster than [[thermal neutron]]s, it is more accurately termed an [[epithermal neutron|epithermal reactor]] than a thermal reactor. It uses [[supercritical fluid|supercritical water]] as the working fluid. SCWRs are basically [[light water reactor]]s (LWR) operating at higher pressure and temperatures with a direct, once-through heat exchange cycle. As most commonly envisioned, it would operate on a direct cycle, much like a boiling water reactor ([[BWR]]), but since it uses supercritical water (not to be confused with [[Critical mass (nuclear)|critical mass]]) as the working fluid, it would have only one water phase present, which makes the supercritical heat exchange method more similar to a pressurized water reactor ([[Pressurized water reactor|PWR]]). It could operate at much higher temperatures than both current PWRs and BWRs.

Supercritical water-cooled reactors (SCWRs) are promising advanced nuclear systems because of their high [[thermal efficiency]] (i.e., about 45% vs. about 33% efficiency for current LWRs) and considerable plant simplification.

The main mission of the SCWR is generation of low-cost [[electricity]]. It is built upon two proven technologies, LWRs, which are the most commonly deployed power generating reactors in the world, and supercritical [[fossil fuel]] fired [[boiler]]s, a large number of which are also in use around the world. The SCWR concept is being investigated by 32 organizations in 13 countries.{{citation needed|date=October 2012}}

A SCWR Design under development is the [[VVER]]-1700/393 (VVER-SCWR or VVER-SKD) — a Russian Supercritical-water-cooled reactor with double-inlet-core and a [[breeder reactor|breeding ratio]] of 0.95.<ref name="powertecrussia.com">{{cite web |url=http://www.powertecrussia.com/blog/tag/nuclear-power/ |title=Technology Developments & Plant Efficiency for the Russian Nuclear Power Generation Market Wednesday |date=March 24, 2010}}</ref>

=== Fast reactors ===
A [[Fast-neutron reactor|fast reactor]] directly uses the fast neutrons emitted by fission, without moderation. Unlike thermal neutron reactors, fast neutron reactors can be configured to "burn", or fission, all [[actinides]], and given enough time, therefore drastically reduce the actinides fraction in [[spent nuclear fuel]] produced by the present world fleet of thermal neutron [[Light Water Reactor]]s, thus closing the [[Nuclear fuel cycle]]. Alternatively, if configured differently, they can also [[breeder reactor|breed]] more actinide fuel than they consume.

==== Gas-cooled fast reactor (GFR) ====
[[File:Gas-Cooled Fast Reactor Schemata.svg|right|thumb|Gas-Cooled Fast Reactor (GFR)]]
{{Main|Gas-cooled fast reactor}}
The '''gas-cooled fast reactor''' (GFR)<ref name="Roadmap"/> system features a fast-neutron spectrum and closed [[Nuclear fuel cycle|fuel cycle]] for efficient conversion of [[Fertile material|fertile uranium]] and management of [[actinide]]s. The reactor is [[helium]]-cooled and with an outlet temperature of 850 °C it is an evolution of the [[Very High Temperature Reactor]](VHTR) to a more sustainable fuel cycle. It will use a direct [[Brayton cycle]] [[Closed-cycle gas turbine|gas turbine]] for high thermal efficiency. Several fuel forms are being considered for their potential to operate at very high temperatures and to ensure an excellent retention of [[Nuclear fission|fission]] products: composite [[ceramic]] fuel, advanced fuel particles, or ceramic clad elements of actinide compounds. Core configurations are being considered based on pin- or plate-based fuel assemblies or prismatic blocks.

The European Sustainable Nuclear Industrial Initiative is funding three Generation IV reactor systems, one of which is a gas-cooled fast reactor, called ''Allegro'', 100 MW(t), which will be built in a central or eastern European country with construction expected to begin in 2018.<ref name="euronuclear.org">{{cite web |url=https://www.euronuclear.org/1-information/news/Gen-IV.htm |title=The European Sustainable Nuclear Industrial Initiative (ESNII) will support three Generation IV reactor systems: a sodium-cooled fast reactor, or SFR, called ''Astrid'' that is proposed by France; a gas-cooled fast reactor, GFR, called ''Allegro'' supported by central and eastern Europe; and a lead-cooled fast reactor, LFR, technology pilot called ''Myrrha'' that is proposed by Belgium.}}</ref> The central European [[Visegrád Group]] are committed to pursuing the technology.<ref>{{cite web |url=http://www.alphagalileo.org/ViewItem.aspx?ItemId=133111&CultureCode=en |title=The V4G4 Centre of Excellence for performing joint research, development and innovation in the field of Generation-4 (G4) nuclear reactors have been established. 20 July 2013 National Center for Nuclear Research (NCBJ]}}</ref> In 2013 German, British, and French institutes finished a 3 year collaboration study on the follow on industrial scale design, known as ''GoFastR''.<ref>{{cite web |url=http://www.ist-world.org/ProjectDetails.aspx?ProjectId=5cb8f3f283574cc6b2bdbf72533172d8 |title=the European Gas cooled Fast Reactor.}}</ref> They were funded by the EU's 7th FWP framework programme, with the goal of making a sustainable [[VHTR]].<ref>{{cite web |url=http://www.2020-horizon.com/GOFASTR-European-Gas-Cooled-Fast-Reactor%28GOFASTR%29-s312.html |title=The GOFASTR research program}}</ref>

==== Sodium-cooled fast reactor (SFR) ====
[[File:Sodium-Cooled Fast Reactor Schemata.svg|right|thumb|Pool design Sodium-Cooled Fast Reactor (SFR)]]
{{Main|Sodium-cooled fast reactor}}
{{see also|Experimental Breeder Reactor II|S-PRISM|BN-800 reactor|Toshiba 4S}}
The SFR<ref name="Roadmap"/> is a project that builds on two closely related existing projects, the [[LMFBR|liquid metal fast breeder reactor]] and the [[Integral Fast Reactor]].

The goals are to increase the efficiency of uranium usage by [[breeder reactor|breeding]] plutonium and eliminating the need for [[transuranic]] isotopes ever to leave the site. The reactor design uses an unmoderated core running on [[fast neutron]]s, designed to allow any transuranic isotope to be consumed (and in some cases used as fuel). In addition to the benefits of removing the long [[half-life]] transuranics from the waste cycle, the SFR fuel expands when the reactor overheats, and the chain reaction automatically slows down. In this manner, it is passively safe.

The SFR reactor concept is cooled by liquid [[sodium]] and fueled by a metallic alloy of [[uranium]] and [[plutonium]] or [[spent nuclear fuel]], the "nuclear waste" of [[Light Water Reactor]]s. The SFR fuel is contained in steel cladding with liquid sodium filling in the space between the clad elements which make up the fuel assembly. One of the design challenges of an SFR is the risks of handling sodium, which reacts explosively if it comes into contact with water. However, the use of liquid metal instead of water as coolant allows the system to work at atmospheric pressure, reducing the risk of leakage.

The European Sustainable Nuclear Industrial Initiative is funding three Generation IV reactor systems, one of which is a sodium-cooled fast reactor, called ''ASTRID'', Advanced Sodium Technical Reactor for Industrial Demonstration, [[Areva]], [[Commissariat à l'énergie atomique et aux énergies alternatives|CEA]] and [[Électricité de France|EDF]] are leading the design with British collaboration.<ref>{{cite web |url=http://www.power-eng.com/articles/2010/11/areva--cea-secure.html |title=Areva, CEA secure EUR650m funding to develop ASTRID sodium-cooled Generation IV reactor 11/11/2010}}</ref><ref>{{cite web |url=http://www.powermag.com/uk-and-france-sign-landmark-civil-nuclear-cooperation-agreement/ |title=UK and France Sign Landmark Civil Nuclear Cooperation Agreement 02/22/2012 . POWERnews}}</ref> Astrid will be rated about 600 MWe and is expected to be built in France, with construction slated to begin in 2017 near to the [[Phénix]] reactor.<ref name="euronuclear.org"/>

The [[PRC]]'s first commercial-scale, 800 MWe, fast neutron reactor, to be situated near Sanming city in [[Fujian province]] will be a SFR. In 2009 an agreement was signed that would entail the Russian [[BN-800 reactor]] design to be sold to the PRC once it is completed, this would be the first time commercial-scale fast neutron reactors have ever been exported.<ref>{{cite web |url=http://www.world-nuclear-news.org/C-Joint_venture_launched_for_Chinese_fast_reactor-3004104.html |title=Joint venture launched for Chinese fast reactor}}</ref> The [[BN-800 reactor]] became operational in 2014.

In India, the [[Prototype Fast Breeder Reactor]], a 500MWe Sodium cooled fast reactor is under construction, with a completion year of 2014/2015.

==== Lead-cooled fast reactor (LFR) ====
[[File:Lead-Cooled Fast Reactor Schemata.svg|right|thumb|Lead-Cooled Fast Reactor (LFR)]]
{{Main|Lead-cooled fast reactor}}
{{See also|MYRRHA|BREST-300}}
The '''lead-cooled fast reactor'''<ref name="Roadmap">{{cite journal| year=2002 | title=A Technology Roadmap for Generation IV Nuclear Energy Systems | last=US DOE Nuclear Energy Research Advisory Committee |volume=GIF-002-00|url=http://nuclear.energy.gov/genIV/documents/gen_iv_roadmap.pdf}}</ref> features a fast-neutron-spectrum [[lead]] or [[lead]]/[[bismuth]] [[eutectic]] ([[Lead-bismuth eutectic|LBE]]) liquid-metal-cooled reactor with a closed [[Nuclear fuel cycle|fuel cycle]]. Options include a range of plant ratings, including a "battery" of 50 to 150 MW of electricity that features a very long refueling interval, a modular system rated at 300 to 400 MW, and a large monolithic plant option at 1,200 MW. (The term ''battery'' refers to the long-life, factory-fabricated core, not to any provision for electrochemical energy conversion.) The fuel is metal or nitride-based containing [[Fertile material|fertile uranium]] and [[transuranic]]s. The LFR is cooled by natural [[convection]] with a reactor outlet coolant temperature of 550 °C, possibly ranging up to 800 °C with advanced materials. The higher temperature enables the production of [[Thermochemical cycle|hydrogen by thermochemical processes]].

The European Sustainable Nuclear Industrial Initiative is funding three Generation IV reactor systems, one of which is a lead-cooled fast reactor that is also an [[Accelerator-driven system|Accelerator-driven sub-critical]] reactor, called ''Myrrha'', 100 MW(t), which will be built in [[Belgium]] with construction expected to begin after 2014 and the industrial scale version, known as ''Alfred'', slated to be constructed sometime after 2017. A reduced-power model of Myrrha called ''Guinevere'' was started up at [[Mol, Belgium|Mol]] in March 2009.<ref name="euronuclear.org"/>

Two other lead-cooled fast reactors under development are the SVBR-100, a modular 100MWe lead-bismuth cooled fast neutron reactor concept designed by OKB [[Gidropress]] in Russia and the BREST-OD-300 (Lead-cooled fast reactor) 300 MWe, to be developed after the SVBR-100, and built over 2016-20, it will dispense with the [[Uranium-238|fertile blanket]] around the core and will supersede the sodium cooled [[BN-600 reactor]] design, to purportedly give enhanced proliferation resistance.<ref name="powertecrussia.com"/>

== Advantages and disadvantages==
Relative to current nuclear power plant technology, the claimed benefits for 4th generation reactors include:
* Nuclear waste that remains radioactive for a few centuries instead of millennia <ref>{{cite web |title=Strategies to Address Global Warming |url=http://www.columbia.edu/~jeh1/mailings/2009/20090713_Strategies.pdf}}</ref>
* 100-300 times more energy yield from the same amount of nuclear fuel <ref>{{cite web |title=4th Generation Nuclear Power |url=http://www.ossfoundation.us/projects/energy/nuclear}}</ref>
* The ability to consume existing nuclear waste in the production of electricity, that is, a [[closed nuclear fuel cycle]]. This strengthens the arguments for [[nuclear power as renewable energy]].
* Improved operating safety

Nuclear reactors do not emit CO2 during operation, although like all [[low carbon power]] sources, the mining and construction phase can result in CO2 emissions, if energy sources which are not carbon neutral (such as fossil fuels), or CO2 emitting cements are used during the construction process.
A 2012 [[Yale University]] review published in the Journal of Industrial Ecology analyzing {{CO2}} [[life cycle assessment]] (LCA) emissions from [[nuclear power]] determined that:<ref name="Warner + Heath, JoIE">Warner, Ethan S.; Heath, Garvin A. [http://onlinelibrary.wiley.com/doi/10.1111/j.1530-9290.2012.00472.x/full Life Cycle Greenhouse Gas Emissions of Nuclear Electricity Generation: Systematic Review and Harmonization], ''Journal of Industrial Ecology'', [[Yale University]], published online April 17, 2012, doi: 10.1111/j.1530-9290.2012.00472.x.</ref>
{{Quote|''"The collective LCA literature indicates that life cycle [[Greenhouse gas|GHG]] [ greenhouse gas ] emissions from nuclear power are only a fraction of traditional fossil sources and comparable to renewable technologies."''}}
Although the paper primarily dealt with data from [[Generation II reactor]]s, and did not analyze the {{CO2}} emissions by 2050 of the presently under construction [[Generation III reactor]]s, it did summarize the Life Cycle Assessment findings of in development reactor technologies.''{{Quote|FBRs ''[ [[Fast Breeder Reactor]]s ]'' have been evaluated in the LCA literature. The limited literature that evaluates this potential future technology reports [[median]] life cycle GHG emissions... similar to or lower than LWRs[ Gen II [[light water reactor]]s ] and purports to consume little or no [[uranium market|uranium ore]].}}

A specific risk of the sodium-cooled fast reactor is related to using metallic sodium as a coolant. In case of a breach, sodium explosively reacts with water. Fixing breaches may also prove dangerous, as the cheapest noble gas [[argon]] is also used to prevent sodium oxidation. Argon, like helium, can displace oxygen in the air and can pose [[hypoxia (environmental)|hypoxia]] concerns, so workers may be exposed to this additional risk. This is a pertinent problem as can be testified by the events at the [[LMFBR|loop type]] [[Monju Nuclear Power Plant|Prototype Fast Breeder Reactor Monju]] at Tsuruga, Japan.<ref>{{cite news |title=Japan Strains to Fix a Reactor Damaged Before Quake |url=http://www.nytimes.com/2011/06/18/world/asia/18japan.html | work=The New York Times | first=Hiroko |last=Tabuchi |date=17 June 2011}}</ref>
Using lead or molten salts mitigates this problem by making the coolant less reactive and allowing a high freezing temperature and low pressure in case of a leak.

In many cases, there is already a large amount of experience built up with numerous proof of concept Gen IV designs. For example, the reactors at [[Fort St. Vrain Generating Station]] and [[HTR-10]] are similar to the proposed Gen IV [[VHTR]] designs, and the [[LMFBR|pool type]] [[EBR-II]], [[Phénix]] and [[BN-600]] reactor are similar to the proposed pool type Gen IV Sodium Cooled Fast reactors being designed.

== Participating countries ==
The members of the Generation IV International Forum (GIF) are:
* {{ARG}} [http://www.cnea.gov.ar/] (Spanish-only web site)
* {{BRA}} [http://www.aben.com.br/]
* {{CAN}} [http://www.aecl.ca/]
* {{CHN}} [http://www.caea.gov.cn/n602669/n2231600/n2272156/n2272415/167948.html]
* {{EU}} [http://www.euronuclear.org/1-information/generation-IV.htm]
* {{FRA}} [http://www.cea.fr/]
* {{JPN}} [http://www.jaea.go.jp/english/]
* {{KOR}} [http://www.mest.go.kr/index.html] (Korean-only web site)
* {{RUS}} [http://www.rosatom.ru/en/]
* {{RSA}} [http://www.eskom.co.za/live/index.php]
* {{SUI}} [http://www.psi.ch/index_e.shtml]
* {{UK}} [http://www.dti.gov.uk/energy/sources/nuclear/technology/fission/page17924.html]
* {{USA}} [http://nuclear.energy.gov/genIV/neGenIV1.html]

The nine GIF founding members were joined by Switzerland in 2002, Euratom in 2003 and most recently by China and Russia at the end of 2006.<ref>{{cite web | author=[[Commissariat à l'Énergie Atomique]]|title= Future nuclear systems| url=http://nucleaire.cea.fr/fr/nucleaire_futur/pu_schema1ch2.htm}}</ref>

Australia has also shown interest in joining the GIF.{{citation needed|date=March 2012}}

The 36th GIF meeting in [[Brussels]] was held in November 2013.<ref>{{cite web |url=http://events.r20.constantcontact.com/register/event?llr=mscrkjkab&oeidk=a07e7melf609716b2c6 |title=The Generation IV international forum holds their 36th meeting on Monday 18th Nov 2013 in Brussels.}}</ref>

==See also==
{{colbegin|3}}
* [[Nuclear reactor]]
* [[Nuclear material]]
* [[Nuclear physics]]
* [[List of reactor types#Reactor types|List of reactor types]]
* [[Generation II reactor]]
* [[Generation III reactor]]
* [[Integral Fast Reactor]]
* [[Liquid fluoride thorium reactor]]
* [[Breeder reactor]]
* [[Small modular reactor]]
{{colend}}

==References==
{{reflist}}

== External links ==
* [https://inlportal.inl.gov/portal/server.pt?open=514&objID=1361&parentname=CommunityPage&parentid=10&mode=2&in_hi_userid=200&cached=true Article from Idaho National Laboratory detailing some current efforts at developing Gen. IV reactors.]
* [http://www.gen-4.org/ Generation IV International Forum (GIF)]
* [http://nuclear.energy.gov/genIV/neGenIV1.html U.S. Department of Energy Office of Nuclear Energy, Science and Technology]
* [http://www.engr.utk.edu/nuclear/colloquia/slides/Gen%20IV%20U-Tenn%20Presentation.pdf Gen IV presentation]
* [http://www.ecology.at/ecology/files/pr577_1.pdf Science or Fiction - Is there a Future for Nuclear?] (Nov. 2007) - A publication from the Austrian [[Ecology Institute (Austria)|Ecology Institute]] about 'Generation IV' and Fusion reactors.
* {{cite web |url=http://memagazine.asme.org/Articles/2011/December/Nuclear_Power_After_Fukushima.cfm |title=Nuclear Power After Fukushima |author=Gail H. Marcus |date=December 2011 |work=Mechanical Engineering (the magazine of [[ASME]]) |accessdate=23 January 2012}} "In the wake of a severe plant accident, advanced reactor designs are getting renewed attention."
*[http://www.itheo.org/ International Thorium Energy Organisation - www.IThEO.org]
*[http://www.ithec.org/ International Thorium Energy Committee - iThEC]

{{Nuclear fission reactors}}

[[Category:Nuclear power reactor types]]
[[Category:Idaho National Laboratory]]

Schagan (See)

2013-06-28T19:55:39Z

Boundarylayer: external link to documentary added.

{{For|the lake in Jilin, China|Chagan Lake (China)}}
{{Infobox lake
| lake_name = Lake Chagan
| image_lake =
| caption_lake =
| location =
| coords = {{coord|49.935278|79.008889|type:waterbody_region:KZ|display=inline,title}}
| type =
| inflow =
| outflow =
| catchment =
| basin_countries = [[Kazakhstan]]
| length =
| width =
| area =
| depth =
| max-depth =
| volume = {{convert|100000|m3|acre.ft|abbr=on}}
| residence_time =
| shore =
| elevation =
| frozen =
| islands =
| cities =
| reference =
}}

'''Lake Chagan''' (or '''Lake Balapan'''), [[Kazakhstan]], is a [[lake]] created by the [[Chagan (nuclear test)|Chagan nuclear test]] fired on January 15, 1965. Often referenced as "Atomic Lake," the crater lake's volume is approximately {{convert|100000|m3|acre.ft|abbr=on}} and the lake is still [[radioactive]], although it has decayed to the point where people can swim in it. As at the [[Trinity site]] of the first United States nuclear weapon test in [[Alamogordo, New Mexico]], the exposed rock was melted into a glassy substance. To the south, the rim of the crater holds back the waters of a second reservoir.

==See also==
* [[Sedan (nuclear test)]] – An American cratering detonation

==References==
*[http://www.osti.gov/bridge/servlets/purl/408695-xwEMy7/webviewable/408695.pdf On the Soviet program for peaceful uses of nuclear weapons]
*[http://nuclearweaponarchive.org/Russia/Sovwpnprog.html#Chagan On the Soviet nuclear program]

==External links==
*[http://www.youtube.com/watch?v=XEqYroQEtA8 Russia Today documentary that visits the lake at around the 1 minute mark.]
{{Lakes of Kazakhstan}}

[[Category:Craters]]
[[Category:Lakes of Kazakhstan|Chagan]]
[[Category:Peaceful nuclear explosions]]
[[Category:Soviet nuclear explosive tests]]
[[Category:Underground nuclear explosive tests]]

[[pl:Czagan (jezioro)]]

Gravitationstraktor

2013-06-22T06:46:45Z

Boundarylayer: Asteroid impact avoidance added.

{{see also|Asteroid impact avoidance}}
A '''gravity tractor''' (GT) is a [[spacecraft]] that deflects another object in space, typically a [[potentially hazardous object|potentially hazardous asteroid]] that might impact Earth, without physically contacting it, using only its [[gravitational field]] to transmit the required [[impulse (physics)|impulse]].<ref>Edward T. Lu and Stanley G. Love (10 November 2005), [http://www.nature.com/nature/journal/v438/n7065/abs/438177a.html Gravitational tractor for towing asteroids], ''Nature'' '''438''':177–178, {{doi|10.1038/438177a}}. Also, see [http://arxiv.org/abs/astro-ph/0509595 astro-ph/0509595] in the [[ArXiv.org e-print archive|arXiv]].</ref><ref>Yeomans, D.K. et al. (2005) [http://www.lpi.usra.edu/meetings/acm2008/pdf/8273.pdf Using a Gravity Tractor to Help Mitigate Asteroid Collisions with Earth]</ref>
The tractor spacecraft could either hover near the object being deflected or orbit near it.
The concept has two key advantages: namely that essentially nothing need be known about the mechanical composition and structure of the asteroid in advance and that the relatively small amounts of force used enable extremely precise orbit manipulation and determination.

==Advantages==
A number of considerations arise concerning means for avoiding a devastating collision with an asteroidal object, should one be discovered on a trajectory that were determined to lead to Earth impact at some future date. One of the main challenges is how to transmit the [[impulse (physics)|impulse]] required (possibly quite large), to an asteroid of unknown mass, composition, and mechanical strength, without shattering it into fragments, some of which might be themselves dangerous to Earth if left in a collision orbit.
The GT solves this problem by gently accelerating the object as a whole over an extended period of time, using the spacecraft's own mass and associated gravitational field to effect the necessary deflecting force.
Because of the [[Universal gravitation|universality of gravitation]], affecting as it does all mass alike, the asteroid would be accelerated almost uniformly as a whole, with only [[tidal force]]s (which should be extremely small) causing any stresses to its internal structure.

A further advantage is that a transponder on the spacecraft, by continuously monitoring the position and velocity of the tractor/asteroid system, could enable the post-deflection trajectory of the asteroid to be accurately known, ensuring its final placement into a safe orbit.<ref>''Threat Mitigation: The Gravity Tractor''  (2006) Schweickart, Russell; Chapman, Clark; Durda, Dan; Hut, Piet, Submitted to NASA Workshop on Near-Earth Objects, Vail, Colorado, June 2006 [arXiv:physics/0608157.pdf], available at [http://arxiv.org/abs/physics/0608157]</ref>

==Limitations==
Limitations of the tractor concept include the exhaust configuration. With the most efficient hovering design (that is, pointing the exhaust directly at the target object for maximum force per unit of fuel), the expelled reaction mass hits the target head-on, imparting a force in the exact opposite direction to the gravitational pull of the tractor.<ref>{{cite web |title = New Scientist: Letter to editor re: gravity tractor article, with author response|url= http://www.newscientist.com/article/mg19526151.400-asteroid-deflection.html |date = 2007-08-04 |accessdate = 2010-03-30}}</ref> It would therefore be necessary to use the orbiting-tractor scheme described below, or else design the hovering tractor so that its exhaust is directed at a slight angle away from the object, while still pointing "down" enough to keep a steady hover.<ref>{{cite web |url=http://neo.jpl.nasa.gov/neo/b612_report.html |title= NEAR-EARTH OBJECT (NEO) ANALYSIS OF TRANSPONDER TRACKING AND GRAVITY TRACTOR PERFORMANCE |author= [[Jet Propulsion Laboratory]] |coauthors= D.K. Yeomans, S. Bhaskaran, S.B. Broschart, S.R. Chesley, P.W. Chodas, M.A. Jones, and T.H. Sweetser |date= September 22, 2008 |publisher= [[B612 Foundation]] |pages= 17–22 |format= Microsoft Word (.doc) |accessdate= April 8, 2010}}</ref> This requires greater thrust and correspondingly increased fuel consumption for each m/s change in the target's velocity.

Issues of the effect of [[ion propulsion]] thrust on the dust of asteroids have been raised, suggesting that alternative means to control the [[orbital stationkeeping|station keeping]] position of the gravity tractor may need to be considered. In this respect, [[solar sail]]s have been suggested.<ref>[http://www.centauri-dreams.org/?p=22765 The Asteroid and the Telescope], Paul Gilster, Centauri Dreams News, 2012-05-03, accessed 2012-05-14.</ref>

According to [[Rusty Schweickart]], the [[gravitational tractor]] method is also controversial because during the process of changing an asteroid's trajectory the point on Earth where it could most likely hit would be slowly shifted across different countries. It means that the threat for the entire planet would be minimized at the cost of some specific states' security. In Schweickart's opinion, choosing the way the asteroid should be "dragged" would be a tough diplomatic decision.<ref>{{cite news|url=http://www.wired.com/wiredscience/2009/12/saving-earth-from-an-asteroid/ | title=Saving Earth From an Asteroid Will Take Diplomats, Not Heroes | last=Madrigal | first=Alexis | date=16 December 2009 | publisher=WIRED | accessdate=17 December 2009}}</ref>

==Example==
To get a feel for the magnitude of these issues, let us suppose that a [[Near-Earth object|NEO]] of size around 100 m, and mass of one million metric tons, threatened to impact Earth. Suppose also that

* a velocity correction of 1 cm/s would be adequate to place it in a safe and stable orbit, missing Earth

* that the correction needed to be applied within a period of 10 years.

With these parameters, the required impulse would be: ''V'' × ''M''  = 0.01 [m/s]×109 [kg] = 107 [N-s], so that the average tractor force on the asteroid for 10 years (which is 3.156×108 seconds), would need to be about 0.032 newtons.
An ion-electric spacecraft with a specific impulse of 10,000 N-s per kg, corresponding to an ion beam velocity of 10 km/s (about twenty times that obtained with the best chemical rockets), would require 1,000 kg of reaction mass ([[Xenon]] is currently favored) to provide the impulse.
The kinetic power of the ion beam would then be approximately 317 W; the input electric power to the power converter and ion drive would of course be substantially higher.
The spacecraft would need to have enough mass and remain sufficiently close to the asteroid that the component of the average gravitational force on the asteroid in the desired direction would equal or exceed the required 0.032 N.
Assuming the spacecraft is hovering over the asteroid at a distance of 200 m to its centre of mass, that would
require it to have a mass of about 20 metric tonnes, because due to the [[gravitational force]] we
have

<math>
m_2 = \frac{F r^2}{G m_1}
=\frac{0.032[N] \times (200[m])^2}{6.674 \times 10^{-11} [N m^2 kg^{-2}] \times 10^9 [kg]}
\approx 19200 kg
</math>

Considering possible hovering positions or orbits of the tractor around the asteroid, note that if two objects are gravitationally bound in a mutual orbit, then if one receives an arbitrary impulse which is less than that needed to free it from orbit around the other, because of the gravitational forces between them, the impulse will alter the momentum of both, together regarded as a composite system.
That is, so long as the tractor remains in a bound orbit, any propulsive force applied to it will be effectively transferred to the asteroid it orbits.
This permits a wide variety of orbits or hovering strategies for the tractor.
One obvious possibility is for the spacecraft to orbit the NEO with the normal to the orbit in the direction of the desired force.
The ion beam would then be directed in the opposite direction, also perpendicular to the orbit plane. This would result in the plane of the orbit being shifted somewhat away from the center of the asteroid, "towing" it, while the orbital velocity, normal to the thrust, remains constant. The orbital period would be a few hours, essentially independent of size, but weakly dependent on the density of the target body.

==References==
{{Reflist}}

==External links==
* [http://news.nationalgeographic.com/news/2007/02/070217-asteroid-impact.html National Geographic, February 17, 2007]
* [http://www.newscientist.com/article.ns?id=dn8291 New Scientist, November 9, 2005]
* [http://www.b612foundation.org B612 Foundation]

{{Impact cratering on Earth}}

[[Category:Spaceflight concepts]]

Gravitationstraktor

2013-06-22T06:44:59Z

Boundarylayer: /* Limitations */ Dangers added, weapons use.

A '''gravity tractor''' (GT) is a [[spacecraft]] that deflects another object in space, typically a [[potentially hazardous object|potentially hazardous asteroid]] that might impact Earth, without physically contacting it, using only its [[gravitational field]] to transmit the required [[impulse (physics)|impulse]].<ref>Edward T. Lu and Stanley G. Love (10 November 2005), [http://www.nature.com/nature/journal/v438/n7065/abs/438177a.html Gravitational tractor for towing asteroids], ''Nature'' '''438''':177–178, {{doi|10.1038/438177a}}. Also, see [http://arxiv.org/abs/astro-ph/0509595 astro-ph/0509595] in the [[ArXiv.org e-print archive|arXiv]].</ref><ref>Yeomans, D.K. et al. (2005) [http://www.lpi.usra.edu/meetings/acm2008/pdf/8273.pdf Using a Gravity Tractor to Help Mitigate Asteroid Collisions with Earth]</ref>
The tractor spacecraft could either hover near the object being deflected or orbit near it.
The concept has two key advantages: namely that essentially nothing need be known about the mechanical composition and structure of the asteroid in advance and that the relatively small amounts of force used enable extremely precise orbit manipulation and determination.

==Advantages==
A number of considerations arise concerning means for avoiding a devastating collision with an asteroidal object, should one be discovered on a trajectory that were determined to lead to Earth impact at some future date. One of the main challenges is how to transmit the [[impulse (physics)|impulse]] required (possibly quite large), to an asteroid of unknown mass, composition, and mechanical strength, without shattering it into fragments, some of which might be themselves dangerous to Earth if left in a collision orbit.
The GT solves this problem by gently accelerating the object as a whole over an extended period of time, using the spacecraft's own mass and associated gravitational field to effect the necessary deflecting force.
Because of the [[Universal gravitation|universality of gravitation]], affecting as it does all mass alike, the asteroid would be accelerated almost uniformly as a whole, with only [[tidal force]]s (which should be extremely small) causing any stresses to its internal structure.

A further advantage is that a transponder on the spacecraft, by continuously monitoring the position and velocity of the tractor/asteroid system, could enable the post-deflection trajectory of the asteroid to be accurately known, ensuring its final placement into a safe orbit.<ref>''Threat Mitigation: The Gravity Tractor''  (2006) Schweickart, Russell; Chapman, Clark; Durda, Dan; Hut, Piet, Submitted to NASA Workshop on Near-Earth Objects, Vail, Colorado, June 2006 [arXiv:physics/0608157.pdf], available at [http://arxiv.org/abs/physics/0608157]</ref>

==Limitations==
Limitations of the tractor concept include the exhaust configuration. With the most efficient hovering design (that is, pointing the exhaust directly at the target object for maximum force per unit of fuel), the expelled reaction mass hits the target head-on, imparting a force in the exact opposite direction to the gravitational pull of the tractor.<ref>{{cite web |title = New Scientist: Letter to editor re: gravity tractor article, with author response|url= http://www.newscientist.com/article/mg19526151.400-asteroid-deflection.html |date = 2007-08-04 |accessdate = 2010-03-30}}</ref> It would therefore be necessary to use the orbiting-tractor scheme described below, or else design the hovering tractor so that its exhaust is directed at a slight angle away from the object, while still pointing "down" enough to keep a steady hover.<ref>{{cite web |url=http://neo.jpl.nasa.gov/neo/b612_report.html |title= NEAR-EARTH OBJECT (NEO) ANALYSIS OF TRANSPONDER TRACKING AND GRAVITY TRACTOR PERFORMANCE |author= [[Jet Propulsion Laboratory]] |coauthors= D.K. Yeomans, S. Bhaskaran, S.B. Broschart, S.R. Chesley, P.W. Chodas, M.A. Jones, and T.H. Sweetser |date= September 22, 2008 |publisher= [[B612 Foundation]] |pages= 17–22 |format= Microsoft Word (.doc) |accessdate= April 8, 2010}}</ref> This requires greater thrust and correspondingly increased fuel consumption for each m/s change in the target's velocity.

Issues of the effect of [[ion propulsion]] thrust on the dust of asteroids have been raised, suggesting that alternative means to control the [[orbital stationkeeping|station keeping]] position of the gravity tractor may need to be considered. In this respect, [[solar sail]]s have been suggested.<ref>[http://www.centauri-dreams.org/?p=22765 The Asteroid and the Telescope], Paul Gilster, Centauri Dreams News, 2012-05-03, accessed 2012-05-14.</ref>

According to [[Rusty Schweickart]], the [[gravitational tractor]] method is also controversial because during the process of changing an asteroid's trajectory the point on Earth where it could most likely hit would be slowly shifted across different countries. It means that the threat for the entire planet would be minimized at the cost of some specific states' security. In Schweickart's opinion, choosing the way the asteroid should be "dragged" would be a tough diplomatic decision.<ref>{{cite news|url=http://www.wired.com/wiredscience/2009/12/saving-earth-from-an-asteroid/ | title=Saving Earth From an Asteroid Will Take Diplomats, Not Heroes | last=Madrigal | first=Alexis | date=16 December 2009 | publisher=WIRED | accessdate=17 December 2009}}</ref>

==Example==
To get a feel for the magnitude of these issues, let us suppose that a [[Near-Earth object|NEO]] of size around 100 m, and mass of one million metric tons, threatened to impact Earth. Suppose also that

* a velocity correction of 1 cm/s would be adequate to place it in a safe and stable orbit, missing Earth

* that the correction needed to be applied within a period of 10 years.

With these parameters, the required impulse would be: ''V'' × ''M''  = 0.01 [m/s]×109 [kg] = 107 [N-s], so that the average tractor force on the asteroid for 10 years (which is 3.156×108 seconds), would need to be about 0.032 newtons.
An ion-electric spacecraft with a specific impulse of 10,000 N-s per kg, corresponding to an ion beam velocity of 10 km/s (about twenty times that obtained with the best chemical rockets), would require 1,000 kg of reaction mass ([[Xenon]] is currently favored) to provide the impulse.
The kinetic power of the ion beam would then be approximately 317 W; the input electric power to the power converter and ion drive would of course be substantially higher.
The spacecraft would need to have enough mass and remain sufficiently close to the asteroid that the component of the average gravitational force on the asteroid in the desired direction would equal or exceed the required 0.032 N.
Assuming the spacecraft is hovering over the asteroid at a distance of 200 m to its centre of mass, that would
require it to have a mass of about 20 metric tonnes, because due to the [[gravitational force]] we
have

<math>
m_2 = \frac{F r^2}{G m_1}
=\frac{0.032[N] \times (200[m])^2}{6.674 \times 10^{-11} [N m^2 kg^{-2}] \times 10^9 [kg]}
\approx 19200 kg
</math>

Considering possible hovering positions or orbits of the tractor around the asteroid, note that if two objects are gravitationally bound in a mutual orbit, then if one receives an arbitrary impulse which is less than that needed to free it from orbit around the other, because of the gravitational forces between them, the impulse will alter the momentum of both, together regarded as a composite system.
That is, so long as the tractor remains in a bound orbit, any propulsive force applied to it will be effectively transferred to the asteroid it orbits.
This permits a wide variety of orbits or hovering strategies for the tractor.
One obvious possibility is for the spacecraft to orbit the NEO with the normal to the orbit in the direction of the desired force.
The ion beam would then be directed in the opposite direction, also perpendicular to the orbit plane. This would result in the plane of the orbit being shifted somewhat away from the center of the asteroid, "towing" it, while the orbital velocity, normal to the thrust, remains constant. The orbital period would be a few hours, essentially independent of size, but weakly dependent on the density of the target body.

==References==
{{Reflist}}

==External links==
* [http://news.nationalgeographic.com/news/2007/02/070217-asteroid-impact.html National Geographic, February 17, 2007]
* [http://www.newscientist.com/article.ns?id=dn8291 New Scientist, November 9, 2005]
* [http://www.b612foundation.org B612 Foundation]

{{Impact cratering on Earth}}

[[Category:Spaceflight concepts]]

Daisy (Werbung)

2013-06-14T03:00:40Z

Boundarylayer: /* Synopsis */

[[File:Commercial-LBJ1964ElectionAdDaisyGirl.ogv|thumb|350px|thumbtime=3|Complete "Daisy" advertisement]]
"'''Daisy'''", sometimes known as "'''Daisy Girl'''" or "'''Peace, Little Girl'''," was a controversial [[Campaign advertising|political advertisement]] aired on television during the [[United States presidential election, 1964|1964 United States presidential election]] by incumbent president [[Lyndon B. Johnson]]'s campaign. Though only aired once (by the campaign), it is considered an important factor in Johnson's [[Landslide victory#Presidential|landslide victory]] over [[Barry Goldwater]] and an important turning point in [[Politics of the United States|political]] and [[advertising]] history. It was created by [[Tony Schwartz (sound archivist)|Tony Schwartz]] of [[DDB Worldwide|Doyle Dane Bernbach]]. It remains one of the most controversial political advertisements ever made.<ref name="Independent Press-Telegram" /><ref name="Kurson" />

== Synopsis ==
The advertisement begins with a little girl (two-year old [[Monique M. Corzilius]]) standing in a meadow with chirping birds, picking the petals of a daisy flower while counting each petal slowly.<ref name="Newsweek-Mar26/Apri2-12" /><ref name="monique-corzilius" /> Because little Monique does not know her numbers perfectly, she repeats some and says others in the wrong order, all of which adds to her childlike appeal.<ref name="Newsweek-Mar26/Apri2-12" /> When she reaches "nine", an ominous-sounding male voice is then heard [[countdown|counting down]] a missile launch, and as the girl's eyes turn toward something she sees in the sky, the camera [[cinematography#Focal length|zoom]]s in until her pupil fills the screen, blacking it out. When the countdown reaches zero, the blackness is instantly replaced by both a simultaneous bright flash and [[thunder]]ous sound,(a sound which in the actual stock recording, due to the low [[speed of sound]] in air, the sound does not reach the camera for a number of seconds after the light flash is recorded, see [[thunder]] for a further explanation) the film continues to roll and footage of a [[nuclear testing|nuclear explosion]], an explosion similar in appearance to the near [[surface burst]] [[Trinity test]] of 1945 is displayed, followed by another cut to footage of a billowing [[mushroom cloud]].

As the [[fireball]] ascends, the final cut is made, this time a cut to a close-up section of [[incandescence]] in the [[mushroom cloud]], over which a [[voiceover]] from Johnson is played, which states emphatically, "These are the stakes! To make a world in which all of God's children can live, or to go into the dark. We must either love each other, or we must die." Another voiceover (sportscaster [[Chris Schenkel]]) then says, "Vote for President Johnson on November 3. The stakes are too high for you to stay home."

==Background==
In the 1964 election, Republican [[Barry Goldwater presidential campaign, 1964|Barry Goldwater]] campaigned on a right-wing message of cutting social programs and aggressive military action. Goldwater's campaign suggested a willingness to use [[nuclear weapons]] in situations when others would find that unacceptable, something which Johnson sought to capitalize on. For example, Johnson used Goldwater's speeches to imply that he would willingly wage a [[Nuclear warfare|nuclear war]], quoting Goldwater: "by one impulse act you could press a button and wipe out 300 million people before sun down." In turn, Goldwater defended himself by accusing Johnson of making the accusation indirectly, and contending that the media blew the issue out of proportion.<ref name=campaign1>{{cite web|title=1964 Johnson v. Goldwater|url=http://www.kennesaw.edu/pols/3380/pres/1964.html|publisher=Kennesaw State University|accessdate=19 November 2011}}</ref> While Johnson wished to de-escalate the [[Vietnam War]], Goldwater was a supporter and even suggested the use of nuclear weapons if necessary.<ref name=hc1>{{cite web|title=Presidential Election of 1964|url=http://www.historycentral.com/elections/1964.html|publisher=History Central|accessdate=22 November 2011}}</ref> The [[attack ad]] was designed to capitalize on these comments.

==Broadcast and impact==
"Daisy" aired only once, during a September 7, 1964 telecast of ''[[David and Bathsheba]]'' on ''[[The NBC Monday Movie]]''. Johnson's campaign was widely criticized for using the prospect of [[Nuclear warfare|nuclear war]], as well as for the implication that Goldwater would start one, to frighten voters. The ad was immediately pulled, but the point was made, appearing on the nightly news and on conversation programs in its entirety. [[Jack Valenti]], who served as a special assistant to Johnson, later suggested that pulling the ad was a calculated move, arguing that "it showed a certain gallantry on the part of the Johnson campaign to withdraw the commercial."<ref name="wgbh" /> Johnson's line "We must either love each other, or we must die" echoes [[W. H. Auden]]'s poem "[[September 1, 1939]]" in which line 88 reads, "We must love one another or die." The words "children" and "the dark" also occur in Auden's poem.

In 1984, [[Walter Mondale]]'s unsuccessful presidential campaign used ads with a similar theme to the Daisy ad. Mondale's advertisements cut between footage of children and footage of ballistic missiles and nuclear explosions, over a soundtrack of the song "[[Teach Your Children]]" by [[Crosby, Stills, Nash & Young]].<ref name="livingroomcandidate" />

==See also==
*[[Political Psychological Rationalization]]
*[[Bill Moyers]]
*[[Negative campaigning]]
*[[Attack ad]]
*[[Comparative advertising]]
*[[Culture during the Cold War]]
*[[Fear mongering]]
*[[Gene Case]]
*[[Children's interests (rhetoric)]]

;Cultural references
*[[Sideshow Bob's Last Gleaming]]
*''[[Fail-Safe (1964 film)|Fail-Safe]]''
*"[[Sunset (Bird of Prey)]]"

== References ==
{{refs
| refs =

<ref name="Independent Press-Telegram">
"The Tony Schwarz commercials are back" (October 30, 1976) ''Independent Press-Telegram'', Long Beach, California
</ref>

<ref name="Kurson">
{{cite web
| url = http://online.wsj.com/article/SB10001424052970204777904576653070396452408.html?KEYWORDS=daisy+girl
| accessdate = 2011-11-07
| last = Kurson
| first = Ken
| title = Book Review: Daisy Petals and Mushroom Clouds - WSJ.com
| date = 2011-11-07
}}
</ref>

<ref name="Newsweek-Mar26/Apri2-12">
{{cite journal
| last = Daly
| first= Michael
| date = March 26 - April 2, 2012
| title = Flower Power
| journal = Newsweek
| location = New York City
| page = 17
| publisher = The Newsweek/Daily Beast Company LLC.
}} One-page interview with Monique Corzilius with stills from the TV ad and photograph of Corzilius, age 50 and living in Phoenix, Arizona, taken for the article.
</ref>

<ref name="monique-corzilius">
[http://conelrad.blogspot.com/2010/09/meet-real-daisy-girl-monique-corzilius.html Daisy Girl]
</ref>

<ref name="wgbh">
[http://openvault.wgbh.org/catalog/org.wgbh.mla:fb173975ae974ed99073a4bf726c2e80689ce4c1 "Interview with Jack Valenti, 1981.”] 04/23/1981.WGBH Media Library & Archives. Retrieved 3 November 2010.
</ref>

<ref name="livingroomcandidate">
[http://www.livingroomcandidate.org/commercials/1984/arms-control-5 Mondale ad]
</ref>

}}

== External links ==
* [http://www.lbjlib.utexas.edu/johnson/media/daisyspot/ Video] of the ad at the [[Lyndon Baines Johnson Library and Museum]]
* [http://conelrad.com/daisy/index.php Production history of "Daisy" with source documents]
* http://conelrad.blogspot.com/2010/09/meet-real-daisy-girl-monique-corzilius.html
* http://conelrad.blogspot.com/2010/09/picking-wrong-daisy-conelrad-correction.html
* http://www.conelrad.com/daisy/interview.php
* http://adage.com/campaigntrail/post?article_id=145995
* [http://www.youtube.com/watch?v=63h_v6uf0Ao The Daisy Ad, (Youtube)]

{{DEFAULTSORT:Daisy (Advertisement)}}
[[Category:United States presidential election, 1964]]
[[Category:Political campaign television commercials]]
[[Category:Lyndon B. Johnson]]
[[Category:Barry Goldwater]]
[[Category:Works about the Cold War]]
[[Category:1964 works]]

Daisy (Werbung)

2013-06-14T02:58:53Z

Boundarylayer: /* Synopsis */

[[File:Commercial-LBJ1964ElectionAdDaisyGirl.ogv|thumb|350px|thumbtime=3|Complete "Daisy" advertisement]]
"'''Daisy'''", sometimes known as "'''Daisy Girl'''" or "'''Peace, Little Girl'''," was a controversial [[Campaign advertising|political advertisement]] aired on television during the [[United States presidential election, 1964|1964 United States presidential election]] by incumbent president [[Lyndon B. Johnson]]'s campaign. Though only aired once (by the campaign), it is considered an important factor in Johnson's [[Landslide victory#Presidential|landslide victory]] over [[Barry Goldwater]] and an important turning point in [[Politics of the United States|political]] and [[advertising]] history. It was created by [[Tony Schwartz (sound archivist)|Tony Schwartz]] of [[DDB Worldwide|Doyle Dane Bernbach]]. It remains one of the most controversial political advertisements ever made.<ref name="Independent Press-Telegram" /><ref name="Kurson" />

== Synopsis ==
The advertisement begins with a little girl (two-year old [[Monique M. Corzilius]]) standing in a meadow with chirping birds, picking the petals of a daisy flower while counting each petal slowly.<ref name="Newsweek-Mar26/Apri2-12" /><ref name="monique-corzilius" /> Because little Monique does not know her numbers perfectly, she repeats some and says others in the wrong order, all of which adds to her childlike appeal.<ref name="Newsweek-Mar26/Apri2-12" /> When she reaches "nine", an ominous-sounding male voice is then heard [[countdown|counting down]] a missile launch, and as the girl's eyes turn toward something she sees in the sky, the camera [[cinematography#Focal length|zoom]]s in until her pupil fills the screen, blacking it out. When the countdown reaches zero, the blackness is instantly replaced by both a simultaneous bright flash and [[thunder]]ous sound,(a sound which in the actual stock recording, due to the low [[speed of sound]] in air, the sound does not reach the camera for a number of seconds after the light flash is recorded) the film continues to roll and footage of a [[nuclear testing|nuclear explosion]], an explosion similar in appearance to the near [[surface burst]] [[Trinity test]] of 1945 is displayed, followed by another cut to footage of a billowing [[mushroom cloud]].

As the [[fireball]] ascends, the final cut is made, this time a cut to a close-up section of [[incandescence]] in the [[mushroom cloud]], over which a [[voiceover]] from Johnson is played, which states emphatically, "These are the stakes! To make a world in which all of God's children can live, or to go into the dark. We must either love each other, or we must die." Another voiceover (sportscaster [[Chris Schenkel]]) then says, "Vote for President Johnson on November 3. The stakes are too high for you to stay home."

==Background==
In the 1964 election, Republican [[Barry Goldwater presidential campaign, 1964|Barry Goldwater]] campaigned on a right-wing message of cutting social programs and aggressive military action. Goldwater's campaign suggested a willingness to use [[nuclear weapons]] in situations when others would find that unacceptable, something which Johnson sought to capitalize on. For example, Johnson used Goldwater's speeches to imply that he would willingly wage a [[Nuclear warfare|nuclear war]], quoting Goldwater: "by one impulse act you could press a button and wipe out 300 million people before sun down." In turn, Goldwater defended himself by accusing Johnson of making the accusation indirectly, and contending that the media blew the issue out of proportion.<ref name=campaign1>{{cite web|title=1964 Johnson v. Goldwater|url=http://www.kennesaw.edu/pols/3380/pres/1964.html|publisher=Kennesaw State University|accessdate=19 November 2011}}</ref> While Johnson wished to de-escalate the [[Vietnam War]], Goldwater was a supporter and even suggested the use of nuclear weapons if necessary.<ref name=hc1>{{cite web|title=Presidential Election of 1964|url=http://www.historycentral.com/elections/1964.html|publisher=History Central|accessdate=22 November 2011}}</ref> The [[attack ad]] was designed to capitalize on these comments.

==Broadcast and impact==
"Daisy" aired only once, during a September 7, 1964 telecast of ''[[David and Bathsheba]]'' on ''[[The NBC Monday Movie]]''. Johnson's campaign was widely criticized for using the prospect of [[Nuclear warfare|nuclear war]], as well as for the implication that Goldwater would start one, to frighten voters. The ad was immediately pulled, but the point was made, appearing on the nightly news and on conversation programs in its entirety. [[Jack Valenti]], who served as a special assistant to Johnson, later suggested that pulling the ad was a calculated move, arguing that "it showed a certain gallantry on the part of the Johnson campaign to withdraw the commercial."<ref name="wgbh" /> Johnson's line "We must either love each other, or we must die" echoes [[W. H. Auden]]'s poem "[[September 1, 1939]]" in which line 88 reads, "We must love one another or die." The words "children" and "the dark" also occur in Auden's poem.

In 1984, [[Walter Mondale]]'s unsuccessful presidential campaign used ads with a similar theme to the Daisy ad. Mondale's advertisements cut between footage of children and footage of ballistic missiles and nuclear explosions, over a soundtrack of the song "[[Teach Your Children]]" by [[Crosby, Stills, Nash & Young]].<ref name="livingroomcandidate" />

==See also==
*[[Political Psychological Rationalization]]
*[[Bill Moyers]]
*[[Negative campaigning]]
*[[Attack ad]]
*[[Comparative advertising]]
*[[Culture during the Cold War]]
*[[Fear mongering]]
*[[Gene Case]]
*[[Children's interests (rhetoric)]]

;Cultural references
*[[Sideshow Bob's Last Gleaming]]
*''[[Fail-Safe (1964 film)|Fail-Safe]]''
*"[[Sunset (Bird of Prey)]]"

== References ==
{{refs
| refs =

<ref name="Independent Press-Telegram">
"The Tony Schwarz commercials are back" (October 30, 1976) ''Independent Press-Telegram'', Long Beach, California
</ref>

<ref name="Kurson">
{{cite web
| url = http://online.wsj.com/article/SB10001424052970204777904576653070396452408.html?KEYWORDS=daisy+girl
| accessdate = 2011-11-07
| last = Kurson
| first = Ken
| title = Book Review: Daisy Petals and Mushroom Clouds - WSJ.com
| date = 2011-11-07
}}
</ref>

<ref name="Newsweek-Mar26/Apri2-12">
{{cite journal
| last = Daly
| first= Michael
| date = March 26 - April 2, 2012
| title = Flower Power
| journal = Newsweek
| location = New York City
| page = 17
| publisher = The Newsweek/Daily Beast Company LLC.
}} One-page interview with Monique Corzilius with stills from the TV ad and photograph of Corzilius, age 50 and living in Phoenix, Arizona, taken for the article.
</ref>

<ref name="monique-corzilius">
[http://conelrad.blogspot.com/2010/09/meet-real-daisy-girl-monique-corzilius.html Daisy Girl]
</ref>

<ref name="wgbh">
[http://openvault.wgbh.org/catalog/org.wgbh.mla:fb173975ae974ed99073a4bf726c2e80689ce4c1 "Interview with Jack Valenti, 1981.”] 04/23/1981.WGBH Media Library & Archives. Retrieved 3 November 2010.
</ref>

<ref name="livingroomcandidate">
[http://www.livingroomcandidate.org/commercials/1984/arms-control-5 Mondale ad]
</ref>

}}

== External links ==
* [http://www.lbjlib.utexas.edu/johnson/media/daisyspot/ Video] of the ad at the [[Lyndon Baines Johnson Library and Museum]]
* [http://conelrad.com/daisy/index.php Production history of "Daisy" with source documents]
* http://conelrad.blogspot.com/2010/09/meet-real-daisy-girl-monique-corzilius.html
* http://conelrad.blogspot.com/2010/09/picking-wrong-daisy-conelrad-correction.html
* http://www.conelrad.com/daisy/interview.php
* http://adage.com/campaigntrail/post?article_id=145995
* [http://www.youtube.com/watch?v=63h_v6uf0Ao The Daisy Ad, (Youtube)]

{{DEFAULTSORT:Daisy (Advertisement)}}
[[Category:United States presidential election, 1964]]
[[Category:Political campaign television commercials]]
[[Category:Lyndon B. Johnson]]
[[Category:Barry Goldwater]]
[[Category:Works about the Cold War]]
[[Category:1964 works]]

Daisy (Werbung)

2013-06-14T02:53:47Z

Boundarylayer: /* Synopsis */ 1. There is no firestorm shown in the film. No.2 the thunderous sound was editted to coincide with the flash in post production, in actual stock footage there is a delay between the flash and the sound, see thunder

[[File:Commercial-LBJ1964ElectionAdDaisyGirl.ogv|thumb|350px|thumbtime=3|Complete "Daisy" advertisement]]
"'''Daisy'''", sometimes known as "'''Daisy Girl'''" or "'''Peace, Little Girl'''," was a controversial [[Campaign advertising|political advertisement]] aired on television during the [[United States presidential election, 1964|1964 United States presidential election]] by incumbent president [[Lyndon B. Johnson]]'s campaign. Though only aired once (by the campaign), it is considered an important factor in Johnson's [[Landslide victory#Presidential|landslide victory]] over [[Barry Goldwater]] and an important turning point in [[Politics of the United States|political]] and [[advertising]] history. It was created by [[Tony Schwartz (sound archivist)|Tony Schwartz]] of [[DDB Worldwide|Doyle Dane Bernbach]]. It remains one of the most controversial political advertisements ever made.<ref name="Independent Press-Telegram" /><ref name="Kurson" />

== Synopsis ==
The advertisement begins with a little girl (two-year old [[Monique M. Corzilius]]) standing in a meadow with chirping birds, picking the petals of a daisy flower while counting each petal slowly.<ref name="Newsweek-Mar26/Apri2-12" /><ref name="monique-corzilius" /> Because little Monique does not know her numbers perfectly, she repeats some and says others in the wrong order, all of which adds to her childlike appeal.<ref name="Newsweek-Mar26/Apri2-12" /> When she reaches "nine", an ominous-sounding male voice is then heard [[countdown|counting down]] a missile launch, and as the girl's eyes turn toward something she sees in the sky, the camera [[cinematography#Focal length|zoom]]s in until her pupil fills the screen, blacking it out. When the countdown reaches zero, the blackness is instantly replaced by both a simultaneous bright flash and [[thunder]]ous sound,(a sound which in the actual stock recording, due to the low [[speed of sound]] in air, the sound does not reach the camera for a number of seconds after the light flash is recorded) the film continues to roll and footage of a [[nuclear testing|nuclear explosion]], an explosion similar in appearance to the near [[surface burst]] [[Trinity test]] of 1945 is displayed, followed by another cut to footage of a billowing [[mushroom cloud]].

As the [[fireball]] ascends, the final cut is made, this time a cut to a close-up of a section of [[incandescence]] in the [[mushroom cloud]], over which a [[voiceover]] from Johnson is played, which states emphatically, "These are the stakes! To make a world in which all of God's children can live, or to go into the dark. We must either love each other, or we must die." Another voiceover (sportscaster [[Chris Schenkel]]) then says, "Vote for President Johnson on November 3. The stakes are too high for you to stay home."

==Background==
In the 1964 election, Republican [[Barry Goldwater presidential campaign, 1964|Barry Goldwater]] campaigned on a right-wing message of cutting social programs and aggressive military action. Goldwater's campaign suggested a willingness to use [[nuclear weapons]] in situations when others would find that unacceptable, something which Johnson sought to capitalize on. For example, Johnson used Goldwater's speeches to imply that he would willingly wage a [[Nuclear warfare|nuclear war]], quoting Goldwater: "by one impulse act you could press a button and wipe out 300 million people before sun down." In turn, Goldwater defended himself by accusing Johnson of making the accusation indirectly, and contending that the media blew the issue out of proportion.<ref name=campaign1>{{cite web|title=1964 Johnson v. Goldwater|url=http://www.kennesaw.edu/pols/3380/pres/1964.html|publisher=Kennesaw State University|accessdate=19 November 2011}}</ref> While Johnson wished to de-escalate the [[Vietnam War]], Goldwater was a supporter and even suggested the use of nuclear weapons if necessary.<ref name=hc1>{{cite web|title=Presidential Election of 1964|url=http://www.historycentral.com/elections/1964.html|publisher=History Central|accessdate=22 November 2011}}</ref> The [[attack ad]] was designed to capitalize on these comments.

==Broadcast and impact==
"Daisy" aired only once, during a September 7, 1964 telecast of ''[[David and Bathsheba]]'' on ''[[The NBC Monday Movie]]''. Johnson's campaign was widely criticized for using the prospect of [[Nuclear warfare|nuclear war]], as well as for the implication that Goldwater would start one, to frighten voters. The ad was immediately pulled, but the point was made, appearing on the nightly news and on conversation programs in its entirety. [[Jack Valenti]], who served as a special assistant to Johnson, later suggested that pulling the ad was a calculated move, arguing that "it showed a certain gallantry on the part of the Johnson campaign to withdraw the commercial."<ref name="wgbh" /> Johnson's line "We must either love each other, or we must die" echoes [[W. H. Auden]]'s poem "[[September 1, 1939]]" in which line 88 reads, "We must love one another or die." The words "children" and "the dark" also occur in Auden's poem.

In 1984, [[Walter Mondale]]'s unsuccessful presidential campaign used ads with a similar theme to the Daisy ad. Mondale's advertisements cut between footage of children and footage of ballistic missiles and nuclear explosions, over a soundtrack of the song "[[Teach Your Children]]" by [[Crosby, Stills, Nash & Young]].<ref name="livingroomcandidate" />

==See also==
*[[Political Psychological Rationalization]]
*[[Bill Moyers]]
*[[Negative campaigning]]
*[[Attack ad]]
*[[Comparative advertising]]
*[[Culture during the Cold War]]
*[[Fear mongering]]
*[[Gene Case]]
*[[Children's interests (rhetoric)]]

;Cultural references
*[[Sideshow Bob's Last Gleaming]]
*''[[Fail-Safe (1964 film)|Fail-Safe]]''
*"[[Sunset (Bird of Prey)]]"

== References ==
{{refs
| refs =

<ref name="Independent Press-Telegram">
"The Tony Schwarz commercials are back" (October 30, 1976) ''Independent Press-Telegram'', Long Beach, California
</ref>

<ref name="Kurson">
{{cite web
| url = http://online.wsj.com/article/SB10001424052970204777904576653070396452408.html?KEYWORDS=daisy+girl
| accessdate = 2011-11-07
| last = Kurson
| first = Ken
| title = Book Review: Daisy Petals and Mushroom Clouds - WSJ.com
| date = 2011-11-07
}}
</ref>

<ref name="Newsweek-Mar26/Apri2-12">
{{cite journal
| last = Daly
| first= Michael
| date = March 26 - April 2, 2012
| title = Flower Power
| journal = Newsweek
| location = New York City
| page = 17
| publisher = The Newsweek/Daily Beast Company LLC.
}} One-page interview with Monique Corzilius with stills from the TV ad and photograph of Corzilius, age 50 and living in Phoenix, Arizona, taken for the article.
</ref>

<ref name="monique-corzilius">
[http://conelrad.blogspot.com/2010/09/meet-real-daisy-girl-monique-corzilius.html Daisy Girl]
</ref>

<ref name="wgbh">
[http://openvault.wgbh.org/catalog/org.wgbh.mla:fb173975ae974ed99073a4bf726c2e80689ce4c1 "Interview with Jack Valenti, 1981.”] 04/23/1981.WGBH Media Library & Archives. Retrieved 3 November 2010.
</ref>

<ref name="livingroomcandidate">
[http://www.livingroomcandidate.org/commercials/1984/arms-control-5 Mondale ad]
</ref>

}}

== External links ==
* [http://www.lbjlib.utexas.edu/johnson/media/daisyspot/ Video] of the ad at the [[Lyndon Baines Johnson Library and Museum]]
* [http://conelrad.com/daisy/index.php Production history of "Daisy" with source documents]
* http://conelrad.blogspot.com/2010/09/meet-real-daisy-girl-monique-corzilius.html
* http://conelrad.blogspot.com/2010/09/picking-wrong-daisy-conelrad-correction.html
* http://www.conelrad.com/daisy/interview.php
* http://adage.com/campaigntrail/post?article_id=145995
* [http://www.youtube.com/watch?v=63h_v6uf0Ao The Daisy Ad, (Youtube)]

{{DEFAULTSORT:Daisy (Advertisement)}}
[[Category:United States presidential election, 1964]]
[[Category:Political campaign television commercials]]
[[Category:Lyndon B. Johnson]]
[[Category:Barry Goldwater]]
[[Category:Works about the Cold War]]
[[Category:1964 works]]