View source for Breeder reactor

{{Short description|Nuclear reactor generating more fissile material than it consumes}}
{{Use dmy dates|date=January 2020}}
[[File:Ebr1core.png|thumb|upright=1.25|Assembly of the core of [[Experimental Breeder Reactor I]] in [[Idaho]], [[United States]], 1951]]

A '''breeder reactor''' is a [[nuclear reactor]] that generates more [[fissile material]] than it consumes.<ref name=Waltar>{{cite book |title=Fast breeder reactors |vauthors=Waltar AE, Reynolds AB |year=1981 |publisher=Pergamon Press |location=New York |isbn=978-0-08-025983-3 |url=https://books.google.com/books?id=4m6o1jMcIIIC |access-date=4 June 2016 |url-status=live |archive-url=https://web.archive.org/web/20140105044948/http://books.google.com/books?id=4m6o1jMcIIIC |archive-date=5 January 2014}}</ref> These reactors can be [[Nuclear fuel|fueled]] with more-commonly available [[isotopes of uranium]] and [[Isotopes of thorium|thorium]], such as [[uranium-238]] and [[thorium-232]], as opposed to the rare [[uranium-235]] which is used in conventional reactors. These materials are called [[fertile material]]s since they can be bred into fuel by these breeder reactors.

Breeder reactors achieve this because their [[neutron economy]] is high enough to create more fissile fuel than they use. These extra neutrons are absorbed by the fertile material that is loaded into the reactor along with fissile fuel. This [[Irradiation|irradiated]] fertile material in turn transmutes into fissile material which can undergo [[Nuclear fission|fission reactions]].

Breeders were at first found attractive because they made more complete use of uranium fuel than [[light-water reactor]]s, but interest declined after the 1960s as more uranium reserves were found<ref name="Helmreich">Helmreich, J. E. ''Gathering Rare Ores: The Diplomacy of Uranium Acquisition, 1943–1954'', Princeton UP, 1986: ch.&nbsp;10 {{ISBN|0-7837-9349-9}}.</ref> and new methods of [[uranium enrichment]] reduced fuel costs.

== Types ==
[[File:Sasahara.svg|thumb|375px|Production of heavy transuranic actinides in current thermal-neutron fission reactors through neutron capture and decays. Starting at uranium-238, isotopes of plutonium, americium, and curium are all produced. In a fast neutron-breeder reactor, all these isotopes may be burned as fuel.]]

Many types of breeder reactor are possible:

A "breeder" is simply a [[nuclear reactor]] designed for very high [[neutron economy]] with an associated conversion rate higher than 1.0. In principle, almost any reactor design could be tweaked to become a breeder. For example, the [[light-water reactor]], a heavily moderated thermal design, evolved into the [[Reduced moderation water reactor|RMWR]] concept, using light water in a low-density [[supercritical fluid|supercritical]] form to increase the neutron economy enough to allow breeding.

Aside from water-cooled, there are many other types of breeder reactor currently envisioned as possible. These include [[Molten-salt reactor|molten-salt cooled]], [[gas-cooled fast reactor|gas cooled]], and [[liquid metal cooled reactor|liquid-metal cooled]] designs in many variations. Almost any of these basic design types may be fueled by [[uranium]], [[plutonium]], many minor [[Actinide|actinides]], or [[thorium]], and they may be designed for many different goals, such as creating more fissile fuel, long-term steady-state operation, or active burning of [[Radioactive waste|nuclear wastes]].

Extant reactor designs are sometimes divided into two broad categories based upon their neutron spectrum, which generally separates those designed to use primarily uranium and [[Transuranium element|transuranics]] from those designed to use thorium and avoid transuranics. These designs are:
* '''Fast breeder reactors''' (FBRs) which use [[Neutron temperature|'fast' (i.e. unmoderated) neutrons]] to breed fissile plutonium (and possibly higher transuranics) from fertile [[uranium-238]]. The fast spectrum is flexible enough that it can also breed fissile [[uranium-233]] from thorium, if desired.
* '''Thermal breeder reactors''' which use 'thermal-spectrum' or 'slow' (i.e. [[Neutron moderator|moderated]]) neutrons to breed fissile [[Thorium fuel cycle|uranium-233 from thorium]]. Due to the behavior of the various nuclear fuels, a thermal breeder is thought commercially feasible only with thorium fuel, which avoids the buildup of the heavier transuranics.

===Fast breeder reactor===
[[File:LMFBR schematics2.svg|thumb|right|upright=1.6|Schematic diagram showing the difference between the Loop and Pool types of LMFBR]]

All current{{When|date=May 2025}} large-scale FBR [[Nuclear power plant|power stations]] were [[liquid metal cooled reactor|liquid metal fast breeder reactors]] (LMFBR) cooled by liquid [[sodium]]. These have been of one of two designs:{{r|Waltar|page=43}}
*''Loop'' type, in which the primary coolant is circulated through primary heat exchangers outside the reactor tank (but inside the [[biological shield]] due to radioactive {{chem2|^{24}Na|link=sodium-24}} in the primary coolant)[[File:ANLWFuelConditioningFacility.jpg|thumb|upright=1.5|[[Experimental Breeder Reactor II]], which served as the prototype for the Integral Fast Reactor]]
*''Pool'' type, in which the primary heat exchangers and pumps are immersed in the reactor tank

There are only two commercially operating breeder reactors {{as of|lc=yes|2017}}: the [[BN-600 reactor]], at 560 MWe, and the [[BN-800 reactor]], at 880 MWe. Both are Russian sodium-cooled reactors. The designs use liquid metal as the primary coolant, to transfer heat from the core to steam used to power the electricity generating turbines. FBRs have been built cooled by liquid metals other than sodium—some early FBRs used [[mercury (element)|mercury]]; other experimental reactors have used a [[Sodium–potassium alloy|sodium-potassium alloy]]. Both have the advantage that they are liquids at room temperature, which is convenient for experimental rigs but less important for pilot or full-scale power stations.

Three of the proposed [[generation IV reactor]] types are FBRs:<ref>{{cite web |date=December 2002 |title=A Technology Roadmap for Generation IV Nuclear Energy Systems |url=https://www.gen-4.org/gif/upload/docs/application/pdf/2013-09/genivroadmap2002.pdf |url-status=live |archive-url=https://web.archive.org/web/20150701185916/https://www.gen-4.org/gif/upload/docs/application/pdf/2013-09/genivroadmap2002.pdf |archive-date=1 July 2015 |access-date=1 July 2015 |website=Generation IV International Forum |id=GIF-002-00}}</ref>
*[[Gas-cooled fast reactor]] cooled by [[helium]].
*[[Sodium-cooled fast reactor]] based on the existing LMFBR and [[integral fast reactor]] designs.
*[[Lead-cooled fast reactor]] based on Soviet naval propulsion units.

FBRs usually use a [[MOX fuel|mixed oxide fuel]] core of up to 20% [[Plutonium(IV) oxide|plutonium dioxide]] ({{chem2|PuO2}}) and at least 80% [[uranium dioxide]] ({{chem2|UO2}}). Another fuel option is [[nuclear fuel#Metal fuel|metal alloys]], typically a blend of uranium, plutonium, and [[zirconium]] (used because it is "transparent" to neutrons). [[Enriched uranium]] can be used on its own.

Many designs surround the [[Nuclear reactor core|reactor core]] in a blanket of tubes that contain non-fissile uranium-238, which, by capturing fast neutrons from the reaction in the core, converts to fissile [[plutonium-239]] (as is some of the uranium in the core), which is then reprocessed and used as nuclear fuel. Other FBR designs rely on the geometry of the fuel (which also contains uranium-238), arranged to attain sufficient fast neutron capture. The plutonium-239 (or the fissile uranium-235) [[Nuclear cross section|fissile cross-section]] is much smaller in a fast spectrum than in a thermal spectrum, as is the ratio between the <sup>239</sup>Pu/<sup>235</sup>U fission cross-section and the <sup>238</sup>U absorption cross-section. This increases the concentration of <sup>239</sup>Pu/<sup>235</sup>U needed to sustain a [[nuclear chain reaction|chain reaction]], as well as the ratio of breeding to fission.<ref name="Hoffman" />
On the other hand, a fast reactor needs no moderator to [[thermalisation|slow down the neutrons]] at all, taking advantage of the fast neutrons producing a greater number of neutrons per fission than slow neutrons. For this reason ordinary liquid [[water]], being a moderator and [[neutron absorber]], is an undesirable primary coolant for fast reactors. Because large amounts of water in the core are required to cool the reactor, the yield of neutrons and therefore breeding of <sup>239</sup>Pu are strongly affected. Theoretical work has been done on [[reduced moderation water reactor]]s, which may have a sufficiently fast spectrum to provide a breeding ratio slightly over 1. This would likely result in an unacceptable power derating and high costs in a liquid-water-cooled reactor, but the supercritical water coolant of the [[supercritical water reactor]] (SCWR) has sufficient heat capacity to allow adequate cooling with less water, making a fast-spectrum water-cooled reactor a practical possibility.<ref name="Superfast">{{cite conference |last=T. Nakatsuka |display-authors=etal |title=Current Status of Research and Development of Supercritical Water-Cooled Fast Reactor (Super Fast Reactor) in Japan |work=Presented at IAEA Technical Committee Meeting on SCWRs in Pisa, 5–8 July 2010}}</ref>

The type of coolants, temperatures, and fast neutron spectrum puts the fuel cladding material (normally [[Austenitic stainless steel|austenitic stainless]] or ferritic-martensitic steels) under extreme conditions. The understanding of the radiation damage, coolant interactions, stresses, and temperatures are necessary for the safe operation of any reactor core. All materials used to date in sodium-cooled fast reactors have known limits.<ref>{{cite journal |last1=Davis |first1=Thomas P. |date=2018 |title=Review of the iron-based materials applicable for the fuel and core of future Sodium Fast Reactors (SFR) |url=http://www.onr.org.uk/documents/2018/onr-rrr-088.pdf |url-status=live |journal=Office for Nuclear Regulation |archive-url=https://web.archive.org/web/20190103055935/http://www.onr.org.uk/documents/2018/onr-rrr-088.pdf |archive-date=3 January 2019 |access-date=2 January 2019}}</ref> [[Oxide dispersion-strengthened alloy]] steel is viewed as the long-term radiation resistant fuel-cladding material that can overcome the shortcomings of today's material choices.

====Integral fast reactor====

One design of fast neutron reactor, specifically conceived to address the waste disposal and plutonium issues, was the [[integral fast reactor]] (IFR, also known as an integral fast breeder reactor, although the original reactor was designed to not breed a net surplus of fissile material).<ref name="ANL">{{cite web |title=The Integral Fast Reactor |url=http://www.ne.anl.gov/About/reactors/integral-fast-reactor.shtml |url-status=live |archive-url=https://web.archive.org/web/20130917072504/http://www.ne.anl.gov/About/reactors/integral-fast-reactor.shtml |archive-date=17 September 2013 |access-date=20 May 2013 |work=Reactors Designed by Argonne National Laboratory |publisher=Argonne National Laboratory}}</ref><ref>{{cite web |title=National Policy Analysis #378: Integral Fast Reactors: Source of Safe, Abundant, Non-Polluting Power – December 2001 |url=http://www.nationalcenter.org/NPA378.html |url-status=dead |archive-url=https://web.archive.org/web/20160125131513/http://www.nationalcenter.org/NPA378.html |archive-date=25 January 2016 |access-date=13 October 2007}}</ref>

To solve the waste disposal problem, the IFR had an on-site [[electrowinning]] fuel-reprocessing unit that recycled the uranium and all the transuranics (not just plutonium) via [[electroplating]], leaving just short-[[half-life]] [[fission product]]s in the waste. Some of these fission products could later be separated for industrial or medical uses and the rest sent to a waste repository. The IFR pyroprocessing system uses molten [[cadmium]] cathodes and electrorefiners to reprocess metallic fuel directly on-site at the reactor.<ref>Hannum, W.H., Marsh, G.E., and Stanford, G.S. (2004). [http://www.gemarsh.com/wp-content/uploads/Purex&Pyro%20P&S%20Jul04.pdf PUREX and PYRO are not the same] {{Webarchive|url=https://web.archive.org/web/20220123061354/https://www.gemarsh.com/wp-content/uploads/Purex%26Pyro%20P%26S%20Jul04.pdf|date=23 January 2022}}. Physics and Society, July 2004.</ref> Such systems co-mingle all the minor actinides with both uranium and plutonium. The systems are compact and self-contained, so that no plutonium-containing material needs to be transported away from the site of the breeder reactor. Breeder reactors incorporating such technology would most likely be designed with breeding ratios very close to 1.00, so that after an initial loading of enriched uranium and/or plutonium fuel, the reactor would then be refueled only with small deliveries of [[natural uranium]]. A quantity of natural uranium equivalent to a block about the size of a milk crate delivered once per month would be all the fuel such a 1&nbsp;gigawatt reactor would need.<ref>[[University of Washington]] (2004). [http://www.evworld.com/library/energy_numbers.pdf Energy Numbers: Energy in natural processes and human consumption, some numbers] {{Webarchive|url=https://web.archive.org/web/20120915012242/http://www.evworld.com/library/energy_numbers.pdf|date=15 September 2012}}. Retrieved 16 October 2007.</ref> Such self-contained breeders are currently envisioned as the final self-contained and self-supporting ultimate goal of nuclear reactor designers.<ref name="Argonne" /><ref name="Hoffman" /> The project was canceled in 1994 by [[United States Secretary of Energy]] [[Hazel R. O'Leary|Hazel O'Leary]].<ref>{{cite web |last=Kirsch |first=Steve |title=The Integral Fast Reactor (IFR) project: Congress Q&A |url=http://www.skirsch.com/politics/ifr/QAcongressKirsch.htm |url-status=live |archive-url=https://web.archive.org/web/20121216121538/http://skirsch.com/politics/ifr/QAcongressKirsch.htm |archive-date=16 December 2012 |access-date=25 December 2012}}</ref><ref>{{cite web |last=Stanford |first=George S. |title=Comments on the Misguided Termination of the IFR Project |url=http://www.skirsch.com/politics/ifr/O%27Leary%20Problems.pdf |url-status=live |archive-url=https://web.archive.org/web/20121215072610/http://skirsch.com/politics/ifr/O%27Leary%20Problems.pdf |archive-date=15 December 2012 |access-date=25 December 2012}}</ref>

====Other fast reactors====
[[File:MSRE Core.JPG|right|thumb|The graphite core of the [[Molten Salt Reactor Experiment]]]]

The first fast reactor built and operated was the Los Alamos Plutonium Fast Reactor ("[[Clementine (nuclear reactor)|Clementine]]") in Los Alamos, NM.<ref name=":1">{{Cite journal |last1=Patenaude |first1=Hannah K. |last2=Freibert |first2=Franz J. |date=2023-07-03 |title=Oh, My Darling Clementine: A Detailed History and Data Repository of the Los Alamos Plutonium Fast Reactor |journal=Nuclear Technology |language=en |volume=209 |issue=7 |pages=963–1007 |doi=10.1080/00295450.2023.2176686 |issn=0029-5450|doi-access=free |bibcode=2023NucTe.209..963P }}</ref> Clementine was fueled by Ga-stabilized delta-phase Pu and cooled with mercury. It contained a 'window' of Th-232 in anticipation of breeding experiments, but no reports were made available regarding this feature.

Another proposed fast reactor is a fast [[molten salt reactor]], in which the molten salt's moderating properties are insignificant. This is typically achieved by replacing the light metal fluorides (e.g. LiF, {{chem2|BeF2}}) in the salt carrier with heavier metal chlorides (e.g., KCl, RbCl, {{chem2|ZrCl4}}).

Several prototype FBRs have been built, ranging in electrical output from a few light bulbs' equivalent ([[Experimental Breeder Reactor I|EBR-I]], 1951) to over 1,000&nbsp;[[MWe]]. As of 2006, the technology is not economically competitive to thermal reactor technology, but [[nuclear power in India|India]], Japan, China, South Korea, and Russia are all committing substantial research funds to further development of fast breeder reactors, anticipating that rising uranium prices will change this in the long term. Germany, in contrast, abandoned the technology due to safety concerns. The [[SNR-300]] fast breeder reactor was finished after 19 years despite cost overruns summing up to a total of {{Euro}}3.6&nbsp;billion, only to then be abandoned.<ref>Werner Meyer-Larsen: ''Der Koloß von Kalkar''. [[Der Spiegel]] 43/1981 vom 19 October 1981, S. 42–55. [[{{citation |title=Der Koloß von Kalkar |work=[[Der Spiegel]] |series=13 September}}]] (German)</ref>

===Thermal breeder reactor===
[[File:Shippingport Reactor.jpg|thumb|The Shippingport Reactor, used as a prototype light water breeder for five years beginning in August 1977]]

The [[advanced heavy-water reactor]] is one of the few proposed large-scale uses of thorium.<ref>{{cite web |title=Thorium |url=http://www.world-nuclear.org/info/inf62.html#b |url-status=live |archive-url=https://web.archive.org/web/20120419180325/http://www.world-nuclear.org/info/inf62.html#b |archive-date=19 April 2012 |access-date=14 June 2012}}</ref> India is developing this technology, motivated by substantial thorium reserves; almost a third of the world's thorium reserves are in India, which lacks significant uranium reserves.

The third and final core of the [[Shippingport Atomic Power Station]] 60&nbsp;MWe reactor was a light water thorium breeder, which began operating in 1977.<ref>{{cite web |title=Shippingport Atomic Power Station: A National Historic Mechanical Engineering Landmark |url=https://www.asme.org/wwwasmeorg/media/resourcefiles/aboutasme/who%20we%20are/engineering%20history/landmarks/47-shippingport-nuclear-power-station.pdf |url-status=live |archive-url=https://web.archive.org/web/20071129121016/http://files.asme.org/ASMEORG/Communities/History/Landmarks/5643.pdf |archive-date=29 November 2007}}</ref> It used pellets made of [[thorium dioxide]] and uranium-233 oxide; initially, the U-233 content of the pellets was 5–6% in the seed region, 1.5–3% in the blanket region, and none in the reflector region. It operated at 236&nbsp;MWt, generating 60&nbsp;MWe, and ultimately produced over 2.1 billion kilowatt hours of electricity. After five years, the core was removed and found to contain nearly 1.4% more fissile material than when it was installed, demonstrating that breeding from thorium had occurred.<ref>{{cite web |last=Adams |first=Rod |date=October 1, 1995 |title=Light Water Breeder Reactor: Adapting A Proven System |url=https://atomicinsights.com/light-water-breeder-reactor-adapting-proven-system/ |url-status=live |archive-url=https://web.archive.org/web/20121028194257/http://atomicinsights.com/1995/10/light-water-breeder-reactor-adapting-proven-system.html |archive-date=28 October 2012 |access-date=2 October 2012}}</ref><ref>[http://www.world-nuclear.org/info/inf62.html Thorium] {{Webarchive|url=https://web.archive.org/web/20120419180325/http://www.world-nuclear.org/info/inf62.html|date=19 April 2012}} information from the [[World Nuclear Association]]</ref>

A [[liquid fluoride thorium reactor]] is also planned as a thorium thermal breeder. Liquid-fluoride reactors may have attractive features, such as inherent safety, no need to manufacture fuel rods, and possibly simpler reprocessing of the liquid fuel. This concept was first investigated at the [[Oak Ridge National Laboratory]] [[Molten-Salt Reactor Experiment]] in the 1960s. From 2012 it became the subject of renewed interest worldwide.<ref>{{cite news |last=Stenger |first=Victor |author-link=Victor J Stenger |date=12 January 2012 |title=LFTR: A Long-Term Energy Solution? |url=http://www.huffingtonpost.com/victor-stenger/lftr-a-longterm-energy-so_b_1192584.html |url-status=live |archive-url=https://web.archive.org/web/20161222022144/http://www.huffingtonpost.com/victor-stenger/lftr-a-longterm-energy-so_b_1192584.html |archive-date=22 December 2016 |access-date=30 September 2012 |work=Huffington Post}}</ref>

== Fuel resources ==
Breeder reactors could, in principle, extract almost all of the energy contained in uranium or thorium, decreasing fuel requirements by a factor of 100 compared to widely used once-through light water reactors, which extract less than 1% of the energy in the actinide metal (uranium or thorium) mined from the earth.<ref name="Argonne">{{cite web |title=Pyroprocessing Technologies: Recycling Used Nuclear Fuel For A Sustainable Energy Future |publisher=Argonne National Laboratory |url=https://www.anl.gov/sites/www/files/2023-09/Recycling%20Used%20Nuclear%20Fuel%20Brochure.pdf |url-status=live |archive-url=https://web.archive.org/web/20130219051536/http://www.ne.anl.gov/pdfs/12_Pyroprocessing_bro_5_12_v14%5B6%5D.pdf |archive-date=19 February 2013}}</ref> The high fuel-efficiency of breeder reactors could greatly reduce concerns about fuel supply, energy used in mining, and storage of radioactive waste. With [[seawater uranium extraction]] (currently too expensive to be economical), there is enough fuel for breeder reactors to satisfy the world's energy needs for 5 billion years at 1983's total energy consumption rate, thus making nuclear energy effectively a [[renewable energy]].<ref name="sustainablenuclear">{{cite web |title=Breeder reactors: A renewable energy source |last=Cohen |first=Bernard L. |publisher=Argonne National Laboratory |url=http://www.sustainablenuclear.org/PADs/pad11983cohen.pdf |access-date=25 December 2012 |url-status=dead |archive-url=https://web.archive.org/web/20130114062518/http://sustainablenuclear.org/PADs/pad11983cohen.pdf |archive-date=14 January 2013}}</ref><ref>Weinberg, A. M., and R. P. Hammond (1970). "Limits to the use of energy," ''Am. Sci.'' 58, 412.</ref> In addition to seawater, the average crustal granite rocks contain significant quantities of uranium and thorium that with breeder reactors can supply abundant energy for the remaining lifespan of the sun on the main sequence of stellar evolution.<ref>{{cite web |title=There's Atomic Energy in Granite |date=8 February 2013 |url=https://www.nuenergy.org/theres-atomic-energy-in-granite/}}</ref>

=== Nuclear waste ===
{{Actinides vs fission products}}
In broad terms, spent nuclear fuel has three main components. The first consists of [[nuclear fission product|fission products]], the leftover fragments of fuel atoms after they have been split to release energy. Fission products come in dozens of elements and hundreds of isotopes, all of them lighter than uranium. The second main component of spent fuel is transuranics (atoms heavier than uranium), which are generated from uranium or heavier atoms in the fuel when they absorb neutrons but do not undergo fission. All transuranic isotopes fall within the actinide series on the [[periodic table]], and so they are frequently referred to as the actinides. The largest component is the remaining uranium which is around 98.25% uranium-238, 1.1% uranium-235, and 0.65% uranium-236. The U-236 comes from the non-fission capture reaction where U-235 absorbs a neutron but releases only a high energy [[gamma ray]] instead of undergoing fission. 

The physical behavior of the fission products is markedly different from that of the actinides. In particular, fission products do not undergo fission and therefore cannot be used as nuclear fuel. Indeed, because fission products are often [[neutron poison]]s (absorbing neutrons that could be used to sustain a chain reaction), fission products are viewed as nuclear 'ashes' left over from consuming fissile materials. Furthermore, only seven [[long-lived fission product]] isotopes have [[Half-life|half-lives]] longer than a hundred years, which makes their geological storage or disposal less problematic than for transuranic materials.<ref>{{cite web |title=Radioactive Waste Management |publisher=World Nuclear Association |url=http://www.world-nuclear.org/info/Nuclear-Fuel-Cycle/Nuclear-Wastes/Radioactive-Waste-Management |access-date=19 September 2013 |url-status=dead |archive-url=https://web.archive.org/web/20130921055655/http://www.world-nuclear.org/info/Nuclear-Fuel-Cycle/Nuclear-Wastes/Radioactive-Waste-Management/ |archive-date=21 September 2013}}</ref>

With increased concerns about nuclear waste, breeding fuel cycles came under renewed interest as they can reduce actinide wastes, particularly plutonium and minor actinides.<ref name="world-nuclear">{{cite web |title=Supply of Uranium |publisher=World Nuclear Association |url=http://world-nuclear.org/info/inf75.html |access-date=11 March 2012 |url-status=live |archive-url=https://web.archive.org/web/20130212223705/http://www.world-nuclear.org/info/inf75.html |archive-date=12 February 2013}}</ref> Breeder reactors are designed to fission the actinide wastes as fuel and thus convert them to more fission products. After [[spent nuclear fuel]] is removed from a light water reactor, it undergoes a complex decay profile as each nuclide decays at a different rate. There is a large gap in the decay half-lives of fission products compared to transuranic isotopes. If the transuranics are left in the spent fuel, after 1,000 to 100,000 years the slow decay of these transuranics would generate most of the radioactivity in that spent fuel. Thus, removing the transuranics from the waste eliminates much of the long-term radioactivity of spent nuclear fuel.<ref name="aps">{{cite journal |last=Bodansky |first=David |title=The Status of Nuclear Waste Disposal |journal=Physics and Society |volume=35 |issue=1 |publisher=American Physical Society |date=January 2006 |url=http://www.aps.org/units/fps/newsletters/2006/january/article1.html |access-date=30 July 2012 |url-status=live |archive-url=https://web.archive.org/web/20080516010935/http://www.aps.org/units/fps/newsletters/2006/january/article1.html |archive-date=16 May 2008}}</ref>

Today's commercial light-water reactors do breed some new fissile material, mostly in the form of plutonium. Because commercial reactors were never designed as breeders, they do not convert enough uranium-238 into plutonium to replace the uranium-235 consumed. Nonetheless, at least one-third of the power produced by commercial nuclear reactors comes from fission of plutonium generated within the fuel.<ref>{{cite web |title=Information Paper 15 |publisher=World Nuclear Association |url=http://www.world-nuclear.org/info/inf15.html |access-date=15 December 2012 |url-status=dead |archive-url=https://web.archive.org/web/20100330221426/http://www.world-nuclear.org/info/inf15.html |archive-date=30 March 2010}}</ref> Even with this level of plutonium consumption, light water reactors consume only part of the plutonium and minor actinides they produce, and nonfissile [[isotopes of plutonium]] build up, along with significant quantities of other minor actinides.<ref name="SCALE5">{{cite web |title=SCALE 5 Analysis of BWR Spent Nuclear Fuel Isotopic Compositions for Safety Studies |work=ORNL/TM-2010/286 |publisher=OAK RIDGE NATIONAL LABORATORY |author1=U. Mertyurek |author2=M. W. Francis |author3=I. C. Gauld |url=http://info.ornl.gov/sites/publications/Files/Pub27046.pdf |access-date=25 December 2012 |url-status=live |archive-url=https://web.archive.org/web/20130217043714/http://info.ornl.gov/sites/publications/Files/Pub27046.pdf |archive-date=17 February 2013}}</ref>

Breeding fuel cycles attracted renewed interest because of their potential to reduce actinide wastes, particularly various isotopes of plutonium and the minor actinides (neptunium, americium, curium, etc.).<ref name="world-nuclear" /> Since breeder reactors on a closed fuel cycle would use nearly all of the isotopes of these actinides fed into them as fuel, their fuel requirements would be reduced by a factor of about 100. The volume of waste they generate would be reduced by a factor of about 100 as well. While there is a huge reduction in the ''volume'' of waste from a breeder reactor, the [[specific activity|''activity'']] of the waste is about the same as that produced by a light-water reactor.<ref>{{cite web |title=Fast Breeder Reactors |url=https://fas.org/rlg/3_15_2010%20Fast%20Breeder%20Reactors%201.pdf |url-status=live |archive-url=https://web.archive.org/web/20160329001222/http://fas.org/rlg/3_15_2010%20Fast%20Breeder%20Reactors%201.pdf |archive-date=29 March 2016 |access-date=4 June 2016}}</ref>

Waste from a breeder reactor has a different decay behavior because it is made up of different materials. Breeder reactor waste is mostly fission products, while light-water reactor waste is mostly unused uranium isotopes and a large quantity of transuranics. After spent nuclear fuel has been removed from a light-water reactor for longer than 100,000 years, the transuranics would be the main source of radioactivity. Eliminating them would eliminate much of the long-term radioactivity from the spent fuel.<ref name="aps" />

In principle, breeder fuel cycles can recycle and consume all actinides,<ref name="sustainablenuclear" /> leaving only fission products. As the graphic in this section indicates, fission products have a peculiar "gap" in their aggregate half-lives, such that no fission products have a half-life between 91 and 200,000 years. As a result of this physical oddity, after several hundred years in storage, the activity of the [[radioactive waste]] from an FBR would quickly drop to the low level of the [[long-lived fission products]]. However, to obtain this benefit requires the highly efficient separation of transuranics from spent fuel. If the [[nuclear reprocessing|fuel reprocessing]] methods used leave a large fraction of the transuranics in the final waste stream, this advantage would be greatly reduced.<ref name="Argonne" />

The FBR's fast neutrons can fission actinide nuclei with even numbers of both protons and neutrons. Such nuclei usually lack the low-speed "thermal neutron" [[doppler broadening|resonances]] of fissile fuels used in LWRs.<ref>{{cite web |title=Neutron Cross Sections4.7.2 |url=http://www.kayelaby.npl.co.uk/atomic_and_nuclear_physics/4_7/4_7_2.html |url-status=dead |archive-url=https://web.archive.org/web/20130101101959/http://www.kayelaby.npl.co.uk/atomic_and_nuclear_physics/4_7/4_7_2.html |archive-date=1 January 2013 |access-date=17 December 2012 |publisher=National Physical Laboratory}}</ref> The thorium fuel cycle inherently produces lower levels of heavy actinides. The fertile material in the thorium fuel cycle has an atomic weight of 232, while the fertile material in the uranium fuel cycle has an atomic weight of 238. That mass difference means that thorium-232 requires six more neutron capture events per nucleus before the transuranic elements can be produced. In addition to this simple mass difference, the reactor gets two chances to fission the nuclei as the mass increases: First as the effective fuel nuclei U233, and as it absorbs two more neutrons, again as the fuel nuclei U235.<ref>{{cite web |last=David |first=Sylvain |author2=Elisabeth Huffer |author3=Hervé Nifenecker |title=Revisiting the thorium-uranium nuclear fuel cycle |url=http://www.europhysicsnews.org/index.php?option=article&access=standard&Itemid=129&url=/articles/epn/pdf/2007/02/epn07204.pdf |url-status=dead |archive-url=https://web.archive.org/web/20070712172902/http://www.europhysicsnews.org/index.php?option=article&access=standard&Itemid=129&url=%2Farticles%2Fepn%2Fpdf%2F2007%2F02%2Fepn07204.pdf |archive-date=12 July 2007 |access-date=11 November 2018 |publisher=europhysicsnews}}</ref><ref>{{cite web |title=Fissionable Isotopes |url=http://hyperphysics.phy-astr.gsu.edu/hbase/NucEne/fission.html |url-status=live |archive-url=https://web.archive.org/web/20121108064526/http://hyperphysics.phy-astr.gsu.edu/hbase/nucene/fission.html |archive-date=8 November 2012 |access-date=25 December 2012}}</ref>

A reactor whose main purpose is to destroy actinides rather than increasing fissile fuel-stocks is sometimes known as a '''burner reactor'''. Both breeding and burning depend on good neutron economy, and many designs can do either. Breeding designs surround the core by a [[breeding blanket]] of fertile material. Waste burners surround the core with non-fertile wastes to be destroyed. Some designs add neutron reflectors or absorbers.<ref name="Hoffman" />

==Design==
{|class="wikitable sortable" style="text-align:center; margin-left:10px" align="right" border="1"
|+Fission probabilities of selected actinides, thermal vs. fast neutrons.<ref>{{cite web |title=Plentiful Energy: The Story of the Integral Fast Reactor |url=https://gsdm.u-tokyo.ac.jp/file/140528gps_chang.pdf |page=21 |access-date=2 March 2015 |url-status=live |archive-url=https://web.archive.org/web/20141027012652/http://gsdm.u-tokyo.ac.jp/file/140528gps_chang.pdf |archive-date=27 October 2014}}</ref><ref>{{cite web |title=Cross Section Table |url=https://wwwndc.jaea.go.jp/CN14/index.html}}</ref>
The percentages of thermal and fast fission indicate the fraction of nuclei fissioned when hit by a respective neutron. The remainder undergoes neutron capture.
|-
!Isotope !! Thermal fission<br>cross section !! Thermal<br>fission<br>% !! Fast fission<br>cross section !! Fast<br>fission<br>%
|-
|{{sort|710|Th-232}} || 53.71 microbarn || 1 n || 79.94 millibarn || 3 n
|-
|{{sort|720|U-232}} || 76.52 [[barn (unit)|barn]] || 59 || 2.063 barn || 95
|-
|{{sort|730|U-233}} || 531.3 barn || 89 || 1.908 barn || 93
|-
|{{sort|740|U-235}} || 585.1 barn || 81 || 1.218 barn || 80
|-
|{{sort|750|U-238}} || 16.8 microbarn || 1 n || 306.4 millibarn || 11
|-
|{{sort|760|Np-237}} || 20.19 millibarn || 3 n || 1.336 barn || 27
|-
|{{sort|770|Pu-238}} || 17.77 barn || 7 || 1.968 barn || 70
|-
|{{sort|780|Pu-239}} || 747.4 barn || 63 || 1.802 barn || 85
|-
|{{sort|790|Pu-240}} || 36.21 millibarn || 1 n || 1.328 barn || 55
|-
|{{sort|800|Pu-241}} || 1012 barn || 75 || 1.626 barn || 87
|-
|{{sort|810|Pu-242}} || 2.436 millibarn || 1 n || 1.151 barn || 53
|-
|{{sort|820|Am-241}} || 3.122 barn || 1 n || 1.395 barn || 21
|-
|{{sort|830|Am-242m}} || 6401 barn || 75 || 1.834 barn || 94
|-
|{{sort|840|Am-243}} || 81.58 millibarn || 1 n || 1.081 barn || 23
|-
|{{sort|850|Cm-242}} || 4.665 barn || 1 n || 1.775 barn || 10
|-
|{{sort|860|Cm-243}} || 587.4 barn || 78 || 2.432 barn || 94
|-
|{{sort|870|Cm-244}} || 1.022 barn || 4 n || 1.733 barn || 33
|-
|colspan=5|n=non-fissile
|}

=== Conversion ratio ===
One measure of a reactor's performance is the "conversion ratio", defined as the ratio of new fissile atoms produced to fissile atoms consumed. All proposed nuclear reactors except specially designed and operated actinide burners<ref name="Hoffman">{{cite web |title=Preliminary Core Design Studies for the Advanced Burner Reactor over a Wide Range of Conversion Ratios |id=ANL-AFCI-177 |website=Argonne National Laboratory |author=E. A. Hoffman |author2=W. S. Yang |author3=R. N. Hill |url=https://publications.anl.gov/anlpubs/2008/05/61507.pdf}}</ref> experience some degree of conversion. As long as there is any amount of a fertile material within the [[neutron flux]] of the reactor, some new fissile material is always created. When the conversion ratio is greater than 1, it is often called the "breeding ratio".

For example, commonly used light water reactors have a conversion ratio of approximately 0.6. [[Pressurized heavy-water reactor|Pressurized heavy-water reactors]] running on natural uranium have a conversion ratio of 0.8.<ref>{{cite web |last=Kadak |first=Prof. Andrew C. |title=Lecture 4, Fuel Depletion & Related Effects |work=Operational Reactor Safety 22.091/22.903 |publisher=Hemisphere, as referenced by MIT |page=Table 6–1, "Average Conversion or Breeding Ratios for Reference Reactor Systems" |url=http://www.learningace.com/doc/3103775/a22b70ccd4d6c2b95d5cc687c2e09c06/mit22_091s08_lec04 |access-date=24 December 2012 |url-status=dead |archive-url=https://web.archive.org/web/20151017114605/http://www.learningace.com/doc/3103775/a22b70ccd4d6c2b95d5cc687c2e09c06/mit22_091s08_lec04 |archive-date=17 October 2015}}</ref> In a breeder reactor, the conversion ratio is higher than 1. "Break-even" is achieved when the conversion ratio reaches 1.0 and the reactor produces as much fissile material as it uses.

=== Doubling time ===
The [[doubling time]] is the amount of time it would take for a breeder reactor to produce enough new fissile material to replace the original fuel and additionally produce an equivalent amount of fuel for another nuclear reactor. This was considered an important measure of breeder performance in early years, when uranium was thought to be scarce. However, since uranium is more abundant than thought in the early days of nuclear reactor development, and given the amount of plutonium available in spent reactor fuel, doubling time has become a less important metric in modern breeder-reactor design.<ref>{{cite web |title=Who is afraid of breeders? |publisher=Indira Gandhi Centre for Atomic Research, Kalpakkam 603 102, India |first1=Placid |last1=Rodriguez |first2=S. M. |last2=Lee |url=http://www.iisc.ernet.in/currsci/nov251998/articles13.htm |access-date=24 December 2012 |url-status=live |archive-url=https://web.archive.org/web/20130326060136/http://www.iisc.ernet.in/currsci/nov251998/articles13.htm |archive-date=26 March 2013}}</ref><ref>{{cite news |title=Fast breeder reactor: Is advanced fuel necessary? |author=R. Prasad |location=Chennai, India |work=[[The Hindu]] |date=10 October 2002 |url=http://www.hindu.com/thehindu/seta/2002/10/10/stories/2002101000030200.htm |url-status=dead |archive-url=https://web.archive.org/web/20031205071218/http://www.hindu.com/thehindu/seta/2002/10/10/stories/2002101000030200.htm |archive-date=5 December 2003}}</ref>

=== Burnup ===
"[[Burnup]]" is a measure of how much energy has been extracted from a given mass of heavy metal in fuel, often expressed (for power reactors) in terms of gigawatt-days per ton of heavy metal. Burnup is an important factor in determining the types and abundances of isotopes produced by a fission reactor. Breeder reactors by design have high burnup compared to a conventional reactor, as breeder reactors produce more of their waste in the form of fission products, while most or all of the actinides are meant to be fissioned and destroyed.<ref>{{cite web |title=Fast Reactor Systems and Innovative Fuels for Minor Actinides Homogeneous Recycling |url=https://inis.iaea.org/collection/NCLCollectionStore/_Public/45/089/45089649.pdf |url-status=live |archive-url=https://web.archive.org/web/20161013023325/https://www.iaea.org/NuclearPower/Downloadable/Meetings/2013/2013-03-04-03-07-CF-NPTD/T8.3/T8.3.calabrese.pdf |archive-date=13 October 2016}}</ref>

In the past, breeder-reactor development focused on reactors with low breeding ratios, from 1.01 for the [[Shippingport Reactor]]<ref>Adams, R. (1995). [http://www.atomicinsights.com/oct95/LWBR_oct95.html Light Water Breeder Reactor] ({{Webarchive|url=https://web.archive.org/web/20070915175600/http://www.atomicinsights.com/oct95/LWBR_oct95.html |date=15 September 2007}}), ''Atomic Energy Insights'' '''1'''.</ref><ref>Kasten, P. R. (1998) [http://www.princeton.edu/~globsec/publications/pdf/7_3kasten.pdf Review of the Radkowsky Thorium Reactor Concept] ({{webarchive|url=https://web.archive.org/web/20090225154333/http://www.princeton.edu/~globsec/publications/pdf/7_3kasten.pdf |date=25 February 2009}}). ''Science & Global Security'' '''7''', 237–269.</ref> running on thorium fuel and cooled by conventional light water to over 1.2 for the Soviet [[BN-350 reactor|BN-350]] liquid-metal-cooled reactor.<ref>[http://hyperphysics.phy-astr.gsu.edu/hbase/nucene/fasbre.html Fast Breeder Reactors] ({{Webarchive|url=https://web.archive.org/web/20060911211311/http://hyperphysics.phy-astr.gsu.edu/HBASE//nucene/fasbre.html |date=11 September 2006}}), Department of Physics & Astronomy, [[Georgia State University]]. Retrieved 16 October 2007.</ref> Theoretical models of breeders with liquid sodium coolant flowing through tubes inside fuel elements ("tube-in-shell" construction) suggest breeding ratios of at least 1.8 are possible on an industrial scale.<ref>Hiraoka, T., Sako, K., Takano, H., Ishii, T., and Sato, M. (1991). [http://www.osti.gov/energycitations/product.biblio.jsp?osti_id=5560940 A high-breeding fast reactor with fission product gas purge/tube-in-shell metallic fuel assemblies] ({{Webarchive|url=https://web.archive.org/web/20070929120507/http://www.osti.gov/energycitations/product.biblio.jsp?osti_id=5560940 |date=29 September 2007}}). ''Nuclear Technology'' '''93''', 305–329.</ref> The Soviet BR-1 test reactor achieved a breeding ratio of 2.5 under non-commercial conditions.<ref name="Korobeinikov_2014"/>

=== Reprocessing ===
Fission of the nuclear fuel in any reactor unavoidably produces neutron-absorbing [[fission products]]. The fertile material from a breeder reactor then needs to be [[nuclear reprocessing|reprocessed]] to remove those [[neutron poison]]s. This step is required to fully utilize the ability to breed as much or more fuel than is consumed. All reprocessing can present a [[nuclear proliferation|proliferation]] concern, since it can extract weapons-usable material from spent fuel.<ref name="Bari">{{cite web |title=Proliferation Risk Reduction Study ofAlternative Spent Fuel Processing |work=BNL-90264-2009-CP |publisher=Brookhaven National Laboratory |author=R. Bari |year=2009 |display-authors=etal |url=http://www.bnl.gov/isd/documents/70289.pdf |access-date=16 December 2012 |url-status=live |archive-url=https://web.archive.org/web/20130921054853/http://www.bnl.gov/isd/documents/70289.pdf |archive-date=21 September 2013}}</ref> The most common reprocessing technique, [[PUREX]], presents a particular concern since it was expressly designed to separate plutonium. Early proposals for the breeder-reactor fuel cycle posed an even greater proliferation concern because they would use PUREX to separate plutonium in a highly attractive isotopic form for use in nuclear weapons.<ref name="Bathke1">{{cite web |title=An Assessment of the Proliferation Resistance of Materials in Advanced Fuel Cycles |publisher=Department of Energy |author=C.G. Bathke |year=2008 |display-authors=etal |url=http://www.ne.doe.gov/peis/references/RM874_Bathkeetal_2008.pdf |access-date=16 December 2012 |url-status=dead |archive-url=https://web.archive.org/web/20090604220247/http://www.ne.doe.gov/peis/references/RM874_Bathkeetal_2008.pdf |archive-date=4 June 2009}}</ref><ref>{{cite web |title=An Assessment of the Proliferation Resistance of Materials in Advanced Nuclear Fuel Cycles |year=2008 |url=http://www.armscontrolcenter.com/resources/BathkeProlifResistSlidesApril08.pdf |access-date=16 December 2012 |url-status=dead |archive-url=https://web.archive.org/web/20130921054802/http://www.armscontrolcenter.com/resources/BathkeProlifResistSlidesApril08.pdf |archive-date=21 September 2013}}</ref>

Several countries are developing reprocessing methods that do not separate the plutonium from the other actinides. For instance, the non-water-based [[pyrometallurgical]] electrowinning process, when used to reprocess fuel from an [[integral fast reactor]], leaves large amounts of radioactive actinides in the reactor fuel.<ref name="Argonne" /> More conventional water-based reprocessing systems include SANEX, UNEX, DIAMEX, COEX, and TRUEX, and proposals to combine PUREX with those and other co-processes. All these systems have moderately better proliferation resistance than PUREX, though their adoption rate is low.<ref>{{cite web |title=A New Reprocessing System Composed of PUREX and TRUEX Processes For Total Separation of Long-lived Radionuclides |first1=M. |last1=Ozawa |first2=Y. |last2=Sano |first3=K. |last3=Nomura |first4=Y. |last4=Koma |first5=M. |last5=Takanashi |url=https://www.oecd-nea.org/pt/docs/iem/mol98/session2/SIIpaper1.pdf |access-date=20 September 2013 |url-status=live |archive-url=https://web.archive.org/web/20130921054156/http://www.oecd-nea.org/pt/docs/iem/mol98/session2/SIIpaper1.pdf |archive-date=21 September 2013}}</ref><ref>{{cite web |title=Nuclear Fuel Reprocessing |first1=Michael F. |last1=Simpson |first2=Jack D. |last2=Law |publisher=Idaho National Laboratory |date=February 2010 |url=http://www.inl.gov/technicalpublications/Documents/4460757.pdf |access-date=20 September 2013 |url-status=live |archive-url=https://web.archive.org/web/20130921054442/http://www.inl.gov/technicalpublications/Documents/4460757.pdf |archive-date=21 September 2013}}</ref><ref>{{cite web |title=Proliferation Risk Reduction Study of Alternative Spent Fuel Processing |url=https://www.bnl.gov/isd/documents/70289.pdf |access-date=1 January 2017 |url-status=live |archive-url=https://web.archive.org/web/20170101161936/https://www.bnl.gov/isd/documents/70289.pdf |archive-date=1 January 2017}}</ref>

In the thorium cycle, thorium-232 breeds by converting first to protactinium-233, which then decays to uranium-233. If the protactinium remains in the reactor, small amounts of uranium-232 are also produced, which has the strong gamma emitter [[isotopes of thallium|thallium-208]] in its decay chain. Similar to uranium-fueled designs, the longer the fuel and fertile material remain in the reactor, the more of these undesirable elements build up. In the envisioned commercial [[thorium-based nuclear power|thorium reactors]], high levels of uranium-232 would be allowed to accumulate, leading to extremely high gamma-radiation doses from any uranium derived from thorium. These gamma rays complicate the safe handling of a weapon and the design of its electronics; this explains why uranium-233 has never been pursued for weapons beyond proof-of-concept demonstrations.<ref>{{cite web |title=U-232 and the Proliferation-Resistance of U-233 in Spent Fuel |work=0892-9882/01 |publisher=Science & Global Security, Volume 9 pp 1–32 |author=Kang and Von Hippel |year=2001 |url=http://www.princeton.edu/sgs/publications/sgs/pdf/9_1kang.pdf |access-date=18 December 2012 |url-status=dead |archive-url=https://web.archive.org/web/20150330020952/http://www.princeton.edu/sgs/publications/sgs/pdf/9_1kang.pdf |archive-date=30 March 2015}}</ref>

While the thorium cycle may be proliferation-resistant with regard to uranium-233 extraction from fuel (because of the presence of uranium-232), it poses a proliferation risk from an alternate route of uranium-233 extraction, which involves chemically extracting protactinium-233 and allowing it to decay to pure uranium-233 outside of the reactor. This process is an obvious chemical operation which is not required for normal operation of these reactor designs, but it could feasibly happen beyond the oversight of organizations such as the International Atomic Energy Agency (IAEA), and thus must be safeguarded against.<ref>{{cite web |title=Thorium: Proliferation warnings on nuclear 'wonder-fuel' |year=2012 |url=https://phys.org/news/2012-12-thorium-proliferation-nuclear-wonder-fuel.html |access-date=22 September 2017 |url-status=live |archive-url=https://web.archive.org/web/20170923050943/https://phys.org/news/2012-12-thorium-proliferation-nuclear-wonder-fuel.html |archive-date=23 September 2017}}</ref>

==Production==

Like many aspects of nuclear power, fast breeder reactors have been subject to much controversy over the years. In 2010 the [[International Panel on Fissile Materials]] said "After six decades and the expenditure of the equivalent of tens of billions of dollars, the promise of breeder reactors remains largely unfulfilled and efforts to commercialize them have been steadily cut back in most countries". In Germany, the United Kingdom, and the United States, breeder reactor development programs have been abandoned.<ref>{{cite web |title=It's time to give up on breeder reactors |work=[[Bulletin of the Atomic Scientists]] |author1=M.V. Ramana |author2=Mycle Schneider |author-link1=M.V. Ramana |author-link2=Mycle Schneider |date=May–June 2010 |url=http://fissilematerials.org/library/Breeders_BAS_May_June_2010.pdf |access-date=3 December 2013 |url-status=live |archive-url=https://web.archive.org/web/20131206231057/http://fissilematerials.org/library/Breeders_BAS_May_June_2010.pdf |archive-date=6 December 2013}}</ref><ref name="fbrb2010">{{cite book |title=Fast Breeder Reactor Programs: History and Status |author=Frank von Hippel |publisher=International Panel on Fissile Materials |isbn=978-0-9819275-6-5 |display-authors=etal |date=February 2010 |url=http://fissilematerials.org/library/rr08.pdf |access-date=28 April 2014 |url-status=live |archive-url=https://web.archive.org/web/20200407191232/http://fissilematerials.org/library/rr08.pdf |archive-date=7 April 2020}}</ref> The rationale for pursuing breeder reactors—sometimes explicit and sometimes implicit—was based on the following key assumptions:<ref name=fbrb2010/><ref>{{cite web |title=It's time to give up on breeder reactors |work=Bulletin of the Atomic Scientists |author1=M.V. Ramana |author2=Mycle Schneider |author-link1=M.V. Ramana |author-link2=Mycle Schneider |date=May–June 2010 |url=http://fissilematerials.org/library/Breeders_BAS_May_June_2010.pdf |access-date=3 December 2013 |url-status=live |archive-url=https://web.archive.org/web/20131206231057/http://fissilematerials.org/library/Breeders_BAS_May_June_2010.pdf |archive-date=6 December 2013}}</ref>
*It was expected that uranium would be scarce and high-grade deposits would quickly become depleted if fission power were deployed on a large scale; the reality, however, is that since the end of the [[Cold War]], uranium has been much cheaper and more abundant than early designers expected.<ref>{{cite web |title=Global Uranium Supply and Demand – Council on Foreign Relations |url=http://www.cfr.org/energy/global-uranium-supply-demand/p14705 |access-date=10 February 2012 |url-status=dead |archive-url=https://web.archive.org/web/20120410010518/http://www.cfr.org/energy/global-uranium-supply-demand/p14705 |archive-date=10 April 2012}}</ref>
*It was expected that breeder reactors would quickly become economically competitive with the light-water reactors that dominate nuclear power today, but the reality is that capital costs are at least 25% more than water-cooled reactors.
*It was thought that breeder reactors could be as safe and reliable as light-water reactors, but safety issues are cited as a concern with fast reactors that use a sodium coolant, where a leak could lead to a sodium fire.
*It was expected that the proliferation risks posed by breeders and their "closed" fuel cycle, in which plutonium would be recycled, could be managed. But since plutonium-breeding reactors produce plutonium from U238, and thorium reactors produce fissile U233 from thorium, all breeding cycles could theoretically pose proliferation risks.<ref name="Council">{{cite web |title=Global Uranium Supply and Demand – Council on Foreign Relations |url=http://www.ipcs.org/seminar/nuclear/modular-nuclear-reactors-and-breeder-technology-842.html |access-date=25 July 2012 |url-status=live |archive-url=https://web.archive.org/web/20120505033427/http://www.ipcs.org/seminar/nuclear/modular-nuclear-reactors-and-breeder-technology-842.html |archive-date=5 May 2012}}</ref> However U-232, which is always present in U-233 produced in breeder reactors, is a strong gamma-emitter via its daughter products, and would make weapon handling extremely hazardous and the weapon easy to detect.<ref>''Introduction to Weapons of Mass Destruction'', Langford, R. Everett (2004). Hoboken, New Jersey: John Wiley & Sons. p. 85. {{ISBN|0-471-46560-7}}. "The US tested a few uranium-233 bombs, but the presence of uranium-232 in the uranium-233 was a problem; the uranium-232 is a copious alpha emitter and tended to 'poison' the uranium-233 bomb by knocking stray neutrons from impurities in the bomb material, leading to possible pre-detonation. Separation of the uranium-232 from the uranium-233 proved to be very difficult and not practical. The uranium-233 bomb was never deployed since plutonium-239 was becoming plentiful."</ref>

Some past anti-nuclear advocates have become pro-nuclear power as a clean source of electricity since breeder reactors effectively recycle most of their waste. This solves one of the most-important negative issues of nuclear power. In the documentary ''[[Pandora's Promise]]'', a case is made for breeder reactors because they provide a real high-kW alternative to fossil fuel energy. According to the movie, one pound of uranium provides as much energy as 5,000 [[barrel of oil equivalent|barrels of oil]].<ref>{{cite AV media |people=Len Koch, pioneering nuclear engineer |year=2013 |title=Pandora's Promise |medium=Motion picture |format=DVD, streaming |minutes=11 |publisher=Impact Partners and CNN Films |ref=PandoraPromise_Koch |url=http://pandoraspromise.com/ |access-date=24 April 2014 |url-status=dead |archive-url=https://web.archive.org/web/20140418044236/http://pandoraspromise.com/ |archive-date=18 April 2014 |quote=One pound of uranium, which is the size of my fingertip, if you could release all of the energy, has the equivalent of about 5,000 barrels of oil.}}</ref>

=== Notable reactors ===
{| class="wikitable sortable" style="text-align:center"
|+ Notable breeder reactors<ref name=":1" /><ref name="world-nuclear.org">{{cite web |title=Nuclear Fusion: WNA - World Nuclear Association |url=http://www.world-nuclear.org/info/Current-and-Future-Generation/Fast-Neutron-Reactors/ |access-date=2 March 2015 |url-status=live |archive-url=https://web.archive.org/web/20150316080643/http://world-nuclear.org/info/Current-and-Future-Generation/Fast-Neutron-Reactors/ |archive-date=16 March 2015}}</ref><ref name="pillai-2014">{{cite journal |title=Breeder reactors: A possible connection between metal corrosion and sodium leaks |author=S. R. Pillai, M. V. Ramana |journal=Bulletin of the Atomic Scientists |volume=70 |issue=3 |pages=49–55 |year=2014 |bibcode=2014BuAtS..70c..49P |s2cid=144406710 |doi=10.1177/0096340214531178 |url=http://bos.sagepub.com/content/70/3/49 |access-date=15 February 2015 |url-status=live |archive-url=https://web.archive.org/web/20151017114605/http://bos.sagepub.com/content/70/3/49 |archive-date=17 October 2015|url-access=subscription }}</ref><ref name="IAEA-PRIS">{{cite web |title=Database on Nuclear Power Reactors |publisher=IAEA |work=PRIS |url=http://www.iaea.org/PRIS/ |access-date=15 February 2015 |url-status=live |archive-url=https://web.archive.org/web/20130602010449/http://www.iaea.org/pris/ |archive-date=2 June 2013}}</ref><ref>{{cite web |title=Experimental Breeder Reactor 1 (EBR-1) - Cheeka Tales |url=http://cheekatales.weebly.com/experimental-breeder-reactor-1-ebr-1.html |access-date=2 March 2015 |url-status=live |archive-url=https://web.archive.org/web/20150402120752/http://cheekatales.weebly.com/experimental-breeder-reactor-1-ebr-1.html |archive-date=2 April 2015}}</ref>
|-
!Reactor !! Country<br>when built !! Started !! Shut down !! Design<br>MWe !! Final<br>MWe !! Thermal<br>Power MWt !! [[Capacity factor|Capacity<br>factor]] !! Number of<br>coolant leaks !! [[Neutron temperature|Neutron<br>temperature]] !! Coolant !! Reactor class
|-
|[[Dounreay#DFR|DFR]] || UK || 1962 || 1977 || 14 || 11 || 65 || 34% || 7 || Fast || [[NaK]] || Test
|-
|[[China Experimental Fast Reactor]] || China || 2012 || operating || 20 || 22 || 65|| 40% || 8 || Fast || [[Sodium]] || Test<ref>{{cite web |title=Chinese fast reactor begins high-power operation: New Nuclear - World Nuclear News |url=https://www.world-nuclear-news.org/Articles/Chinese-fast-reactor-begins-high-power-operation}}</ref>
|-
|[[CFR-600]] || China || 2017 || commissioning/2023 || 642 || 682 || 1882 || 34% || 27 || Fast || [[Sodium]] || Commercial<ref>{{cite web |title=China's New Breeder Reactors May Produce More Than Just Watts - IEEE Spectrum |url=https://spectrum.ieee.org/china-breeder-reactor}}</ref>
|-
|[[BN-350 reactor|BN-350]] || Soviet Union || 1973 || 1999 || 350 || 52 || 750 || 43% || 15 || Fast || [[Sodium]] || Prototype
|-
|[[Rapsodie]] || France || 1967 || 1983 || 0 || – || 40 || – || 2 || Fast || Sodium || Test
|-
|[[Phénix]] || France || 1975 || 2010 || 233 || 130 || 563 || 40.5% || 31 || Fast || Sodium || Prototype
|-
|[[Dounreay#PFR|PFR]] || UK || 1976 || 1994 || 234 || 234 || 650 || 26.9% || 20 || Fast || Sodium || Prototype
|-
|KNK II || Germany || 1977 || 1991 || 18 || 17 || 58 || 17.1% || 21 || Fast || Sodium || Research/Test
|-
|[[SNR-300]] || Germany || 1985 || 1991 || 327 || – || – || non-nuclear tests only || – || Fast || Sodium || Prototype/Commercial
|-
|[[BN-600 reactor|BN-600]] || Soviet Union || 1981 || {{sort|9997|operating}} || 560 || 560 || 1470 || 74.2% || 27 || Fast || Sodium || Prototype/Commercial (Gen2)
|-
|[[Fast Flux Test Facility|FFTF]] || US || 1982 || 1993 || 0 || – || 400 || – || 1 || Fast || Sodium || Test
|-
|[[Superphénix]] || France || 1985 || 1998 || 1200 || 1200 || 3000 || {{sort|07.9|7.9%}} || 7 || Fast || Sodium || Prototype/Commercial (Gen2)
|-
|[[FBTR]] || India || 1985 || {{sort|9997|operating}} || 13 || – || 40 || – || 6 || Fast || Sodium || Test
|-
|[[Prototype Fast Breeder Reactor|PFBR]] || India || 2004 || 2024 || 500 || – || 1250 || – || – || Fast || Sodium || Prototype/Commercial (Gen3)
|-
|[[Jōyō (nuclear reactor)|Jōyō]] || Japan || 1977 || 2007 || 0 || – || 150 || – || – || Fast || Sodium || Test
|-
|[[Monju Nuclear Power Plant|Monju]] || Japan || 1995 || 2017 || 246 || 246 || 714 || {{sort|00.1|trial only}} || 1 || Fast || Sodium || Prototype
|-
|[[BN-800 reactor|BN-800]] || Russia || 2015 || {{sort|9997|operating}} || 789 || 880 || 2100 || 73.4% || – || Fast || Sodium || Prototype/Commercial (Gen3)
|-
|[[Molten-Salt Reactor Experiment|MSRE]] || US || 1965 || 1969 || 0 || – || 7.4 || – || – || Epithermal || Molten salt ([[FLiBe]]) || Test
|-
|[[Clementine (nuclear reactor)|Clementine]] || US || 1946 || 1952 || 0 || – || 0.025 || – || – || Fast || [[Mercury (element)|Mercury]] || World's First Fast Reactor<ref name=":1" />
|-
|[[Experimental Breeder Reactor I|EBR-1]] || US || 1951 || 1964 || 0.2 || 0.2 || 1.4 || – || – || Fast || [[NaK]] || First Power Reactor
|-
|[[Enrico Fermi Nuclear Generating Station#Fermi 1|Fermi-1]] || US || 1963 || 1972 || 66 || 66 || 200 || – || – || Fast || Sodium || Prototype
|-
|[[Experimental Breeder Reactor II|EBR-2]] || US || 1964 || 1994 || 19 || 19 || 62.5 || – || – || Fast || Sodium || Experimental/Test
|-
|[[Shippingport Atomic Power Station|Shippingport]] || US || 1977<br>as breeder || 1982 || 60 || 60 || 236 || – || – || Thermal || Light Water || Experimental-Core3
|-
|}
{{Clear}}

The Soviet Union constructed a series of fast reactors, the first being mercury-cooled and fueled with plutonium metal, and the later plants sodium-cooled and fueled with plutonium oxide. BR-1 (1955) was 100W (thermal) was followed by BR-2 at 100&nbsp;kW and then the 5&nbsp;MW BR-5.<ref name="Korobeinikov_2014">{{cite conference |author=Valerii Korobeinikov |title=Innovative Concepts Based on Fast Reactor Technology |conference=1st Consultancy Meeting for Review of Innovative Reactor Concepts for Prevention of Severe Accidents and Mitigation of their Consequences |website=International Atomic Energy Agency |date=31 March – 2 April 2014 |url=https://www.iaea.org/NuclearPower/Downloadable/Meetings/2014/2014-03-31-04-02-CM-INPRO/RUSSIA_PPT_MS_Presentations_1st_CM_on_RISC_.pdf |url-status=dead |archive-url=https://web.archive.org/web/20160304072421/https://www.iaea.org/NuclearPower/Downloadable/Meetings/2014/2014-03-31-04-02-CM-INPRO/RUSSIA_PPT_MS_Presentations_1st_CM_on_RISC_.pdf |archive-date=4 March 2016}}</ref> BOR-60 (first criticality 1969) was 60&nbsp;MW, with construction started in 1965.<ref>{{cite web |title=Experimental fast reactor BOR-60 |author=FSUE "State Scientific Center of Russian Federation Research Institute of Atomic Reactors" |url=http://www-dev.niiar.ru/ofibr/en/e_bor60.htm |access-date=15 June 2012 |url-status=live |archive-url=https://web.archive.org/web/20121231133752/http://www-dev.niiar.ru/ofibr/en/e_bor60.htm |archive-date=31 December 2012}}</ref>

==Future plants==
[[File:CEFR (04790005).jpg|thumb|The Chinese Experimental Fast Reactor is a 65 [[watt#Multiples|MW]] (thermal), 20 MW (electric), sodium-cooled, pool-type reactor with a 30-year design lifetime and a target [[burnup]] of 100 MWd/kg.]]

=== India ===
India has been trying to develop fast breeder reactors for decades but suffered repeated delays.<ref>{{cite web |title=India's First Prototype Fast Breeder Reactor Has a New Deadline. Should We Trust It? – the Wire Science |date=20 August 2020 |url=https://science.thewire.in/economy/energy/prototype-fast-breeder-reactor-dae-bhavini-npcil-liquid-sodium-coolant-purchase-orders/}}</ref> By December 2024 the [[Prototype Fast Breeder Reactor]] is due to be completed and commissioned.<ref>{{cite news |last=Srikanth |title=80% of work on fast breeder reactor at Kalpakkam over |work=The Hindu |location=Kalpakkam |date=27 November 2011 |url=https://www.thehindu.com/news/national/tamil-nadu/80-of-work-on-fast-breeder-reactor-at-kalpakkam-over/article2663329.ece |access-date=25 March 2012 |url-status=live |archive-url=https://web.archive.org/web/20111128073219/http://www.thehindu.com/news/states/tamil-nadu/article2663329.ece |archive-date=28 November 2011}}</ref><ref>{{cite news |last=Jaganathan |first=Venkatachari |title=India's new fast-breeder on track, nuclear power from September next |work=Hindustan Times |location=Chennai |date=11 May 2011 |url=http://www.hindustantimes.com/india-news/chennai/India-s-new-fast-breeder-on-track-nuclear-power-from-September-next/Article1-542155.aspx |url-status=dead |access-date=25 March 2012 |archive-url=https://web.archive.org/web/20130513232646/http://www.hindustantimes.com/india-news/chennai/India-s-new-fast-breeder-on-track-nuclear-power-from-September-next/Article1-542155.aspx |archive-date=13 May 2013}}</ref><ref name=":0">{{cite web |title=India's first Prototype Fast Breeder Reactor in final stages of commissioning |website=The New Indian Express |date=30 October 2020 |url=https://www.newindianexpress.com/states/tamil-nadu/2020/oct/30/indias-first-prototype-fast-breeder-reactor-in-final-stages-of-commissioning-2217153.html |access-date=2021-09-20 |url-status=live |archive-url=https://web.archive.org/web/20210920213133/https://www.newindianexpress.com/states/tamil-nadu/2020/oct/30/indias-first-prototype-fast-breeder-reactor-in-final-stages-of-commissioning-2217153.html |archive-date=20 September 2021}}</ref> The program is intended to use fertile thorium-232 to breed fissile uranium-233. India is also pursuing thorium thermal breeder reactor technology. India's focus on thorium is due to the nation's large reserves, though known worldwide reserves of thorium are four times those of uranium. India's Department of Atomic Energy said in 2007 that it would simultaneously construct four more breeder reactors of 500&nbsp;MWe each including two at [[Kalpakkam]].<ref>{{cite web |title=Home – India Defence |url=http://www.india-defence.com/reports/2854 |url-status=dead |archive-url=https://web.archive.org/web/20111124050043/http://www.india-defence.com/reports/2854 |archive-date=24 November 2011}}</ref>{{update inline|date=May 2018}}

[[BHAVINI]], an Indian nuclear power company, was established in 2003 to construct, commission, and operate all stage&nbsp;II fast breeder reactors outlined in [[India's three-stage nuclear power programme]]. To advance these plans, the [[FBR-600]] is a pool-type sodium-cooled reactor with a rating of 600 MWe.<ref>Conceptual Design of PFBR Core

S.M. Lee, S Govindarajan, R. Indira, T.M. John, P. Mohanakrishnan, R. Shankar Singh, S B. Bhoje

Indira Gandhi Centre for Atomic Research (IGCAR), Kalpakkam, India https://inis.iaea.org/collection/NCLCollectionStore/_Public/28/014/28014318.pdf {{Webarchive|url=https://web.archive.org/web/20210920212757/https://inis.iaea.org/collection/NCLCollectionStore/_Public/28/014/28014318.pdf |date=20 September 2021}}</ref><ref>{{cite web |title=FBR-600 - India's Next-gen Commercial Fast Breeder Reactor [CFBR] |url=https://www.aame.in/2015/10/fbr-600-india-next-gen-commercial-fast.html |access-date=2021-09-20 |url-status=live |archive-url=https://web.archive.org/web/20210920213243/https://www.aame.in/2015/10/fbr-600-india-next-gen-commercial-fast.html |archive-date=20 September 2021}}</ref><ref name=":0" />

=== China ===
The [[China Experimental Fast Reactor]] is a 25&nbsp;MW(e) prototype for the planned China Prototype Fast Reactor.<ref>{{cite web |title=IAEA Fast Reactor Database |url=http://www.iaea.org/inisnkm/nkm/aws/frdb/fulltext/13_fastReactorDesigns.pdf#CEFR |access-date=13 March 2011 |url-status=live |archive-url=https://web.archive.org/web/20110628235135/http://www.iaea.org/inisnkm/nkm/aws/frdb/fulltext/13_fastReactorDesigns.pdf#CEFR |archive-date=28 June 2011}}</ref> It started generating power in 2011.<ref>{{cite web |title=China's experimental fast neutron reactor begins generating power |publisher=xinhuanet |date=July 2011 |url=http://news.xinhuanet.com/english2010/china/2011-07/21/c_131000739.htm |access-date=21 July 2011 |url-status=dead |archive-url=https://web.archive.org/web/20160407042906/http://news.xinhuanet.com/english2010/china/2011-07/21/c_131000739.htm |archive-date=7 April 2016}}</ref> China initiated a research and development project in thorium molten-salt thermal breeder-reactor technology (liquid fluoride thorium reactor), formally announced at the [[Chinese Academy of Sciences]] annual conference in 2011. Its ultimate target was to investigate and develop a thorium-based molten salt nuclear system over about 20 years.<ref>{{cite web |title=The future of nuclear power plant safety "are not picky eaters" |first=Xu |last=Qimin |language=zh |date=26 January 2011 |url=http://whb.news365.com.cn/yw/201101/t20110126_2944856.htm |access-date=30 October 2011 |url-status=dead |archive-url=https://archive.today/20120717035636/http://whb.news365.com.cn/yw/201101/t20110126_2944856.htm |archive-date=17 July 2012 |quote=Yesterday, as the Chinese Academy of Sciences of the first to start one of the strategic leader in science and technology projects, "the future of advanced nuclear fission energy – nuclear energy, thorium-based molten salt reactor system" project was officially launched. The scientific goal is 20 years or so, developed a new generation of nuclear energy systems, all the technical level reached in the test and have all the intellectual property rights.}}</ref><ref>{{cite news |last=Clark |first=Duncan |title=China enters race to develop nuclear energy from thorium |work=Environment Blog |publisher=The Guardian (UK) |location=London |date=16 February 2011 |url=https://www.theguardian.com/environment/blog/2011/feb/16/china-nuclear-thorium |access-date=30 October 2011 |url-status=live |archive-url=https://web.archive.org/web/20170519070806/https://www.theguardian.com/environment/blog/2011/feb/16/china-nuclear-thorium |archive-date=19 May 2017}}</ref>{{update inline|date=May 2018}}

=== South Korea ===
South Korea is developing a design for a standardized modular FBR for export, to complement the standardized pressurized water reactor and [[CANDU reactor|CANDU]] designs they have already developed and built, but has not yet committed to building a prototype.
[[File:BN-600 nuclear reactor.jpg|thumb|A cutaway model of the BN-600 reactor, superseded by the [[BN-800 reactor]] family]]

[[File:BN-800 construction.jpg|thumb|Construction of the BN-800 reactor]]

=== Russia ===
Russia has a plan for increasing its fleet of fast breeder reactors significantly. A BN-800 reactor (800&nbsp;MWe) at [[Beloyarsk Nuclear Power Station|Beloyarsk]] was completed in 2012, succeeding a smaller [[BN-600 reactor|BN-600]].<ref>{{cite web |title=Белоярская АЭС: начался выход БН-800 на минимальный уровень мощности |publisher=AtomInfo.ru |url=http://atominfo.ru/newsi/p0401.htm |access-date=27 July 2014 |url-status=live |archive-url=https://web.archive.org/web/20140630200015/http://atominfo.ru/newsi/p0401.htm |archive-date=30 June 2014}}</ref> It reached its full power production in 2016.<ref name="fullpower">{{cite web |title=Russian fast reactor reaches full power |url=http://www.world-nuclear-news.org/NN-Russian-fast-reactor-reaches-full-power-1708165.html |access-date=27 October 2017 |url-status=live |archive-url=https://web.archive.org/web/20171027125917/http://www.world-nuclear-news.org/NN-Russian-fast-reactor-reaches-full-power-1708165.html |archive-date=27 October 2017}}</ref> Plans for the construction of a larger [[BN-1200 reactor]] (1,200&nbsp;MWe) was scheduled for completion in 2018, with two additional BN-1200 reactors built by the end of 2030.<ref>{{cite web |title=До 2030 в России намечено строительство трёх энергоблоков с реакторами БН-1200 |publisher=AtomInfo.ru |url=http://atominfo.ru/newsi/p0662.htm |access-date=27 July 2014 |url-status=live |archive-url=https://web.archive.org/web/20140805100047/http://atominfo.ru/newsi/p0662.htm |archive-date=5 August 2014}}</ref> However, in 2015 [[Rosenergoatom]] postponed construction indefinitely to allow fuel design to be improved after more experience of operating the BN-800 reactor, and among cost concerns.<ref name="wnn-20150416">{{cite news |title=Russia postpones BN-1200 in order to improve fuel design |publisher=World Nuclear News |date=16 April 2015 |url=http://www.world-nuclear-news.org/NN-Russia-postpones-BN-1200-in-order-to-improve-fuel-design-16041502.html |access-date=19 April 2015 |url-status=live |archive-url=https://web.archive.org/web/20150621085931/http://www.world-nuclear-news.org/NN-Russia-postpones-BN-1200-in-order-to-improve-fuel-design-16041502.html |archive-date=21 June 2015}}</ref>

An experimental lead-cooled fast reactor, [[BREST (Reactor)|BREST-300]] will be built at the [[Siberian Chemical Combine]] in [[Seversk]]. The BREST ({{langx|ru|bystry reaktor so svintsovym teplonositelem|italics=yes}}, {{langx|en|fast reactor with lead coolant}}) design is seen as a successor to the BN series and the 300&nbsp;MWe unit at the SCC could be the forerunner to a 1,200&nbsp;MWe version for wide deployment as a commercial power generation unit. The development program is as part of an Advanced Nuclear Technologies Federal Program 2010–2020 that seeks to exploit fast reactors for uranium efficiency while 'burning' radioactive substances that would otherwise be disposed of as waste. Its core would measure about 2.3 metres in diameter by 1.1 metres in height and contain 16 tonnes of fuel. The unit would be refuelled every year, with each fuel element spending five years in total within the core. Lead coolant temperature would be around 540&nbsp;°C, giving a high efficiency of 43%, primary heat production of 700&nbsp;MWt yielding electrical power of 300&nbsp;MWe. The operational lifespan of the unit could be 60 years. The design was expected to be completed by NIKIET in 2014 for construction between 2016 and 2020.<ref>{{cite web |title=Fast moves for nuclear development in Siberia |publisher=World Nuclear Association |url=http://www.world-nuclear-news.org/NN_Fast_moves_for_nuclear_development_in_Siberia_0410121.html |access-date=8 October 2012 |url-status=live |archive-url=https://web.archive.org/web/20121012025225/http://www.world-nuclear-news.org/NN_Fast_moves_for_nuclear_development_in_Siberia_0410121.html |archive-date=12 October 2012}}</ref> 
By the end of 2024 the cooling tower had been built, and the target for starting operation was 2026.{{cn|date=November 2024}}

=== Japan ===
In 2006 the United States, France, and Japan signed an "arrangement" to research and develop sodium-cooled fast reactors in support of the [[Global Nuclear Energy Partnership]].<ref>{{cite web |title=Department of Energy – Generation IV International Forum Signs Agreement to Collaborate on Sodium Cooled Fast Reactors |url=https://www.energy.gov/news/3218.htm |url-status=dead |archive-url=https://web.archive.org/web/20080420215727/http://www.energy.gov/news/3218.htm |archive-date=20 April 2008}}</ref> In 2007 the Japanese government selected [[Mitsubishi Heavy Industries]] as the "core company in FBR development in Japan". Shortly thereafter, [[Mitsubishi FBR Systems]] was launched to develop and eventually sell FBR technology.<ref>{{cite web |title=MHI launches fast breeder group |work=Nuclear Engineering International |date=2 July 2007 |url=https://www.neimagazine.com/news/newsmhi-launches-fast-breeder-group-721 |access-date=13 March 2011 |archive-url=https://web.archive.org/web/20070728025205/http://www.neimagazine.com/story.asp?sectionCode=132&storyCode=2045341 |url-status=live |archive-date=28 July 2007}}</ref>

[[File:CEA Marcoule Site.jpg|thumb|The [[Marcoule Nuclear Site]] in France, location of the [[Phénix]] (on the left)]]

=== France ===
In 2010 the French government allocated {{Euro}}651.6&nbsp;million to the [[Commissariat à l'énergie atomique]] to finalize the design of [[ASTRID (reactor)|ASTRID]] (Advanced Sodium Technological Reactor for Industrial Demonstration), a 600&nbsp;MW fourth-generation reactor design to be finalized in 2020.<ref>{{cite web |title=French government puts up funds for Astrid |author=World Nuclear News |date=16 September 2010 |url=http://www.world-nuclear-news.org/newsarticle.aspx?id=28382 |access-date=15 June 2012 |url-status=dead |archive-url=https://web.archive.org/web/20140714131532/http://www.world-nuclear-news.org/newsarticle.aspx?id=28382 |archive-date=14 July 2014}}</ref><ref>{{cite web |title=Quatrième génération: vers un nucléaire durable |publisher=CEA |language=fr |url=http://www.cea.fr/content/download/33852/575120/file/Reacteurs-generation-4-CEA.pdf |access-date=15 June 2012 |url-status=live |archive-url=https://web.archive.org/web/20120603174020/http://www.cea.fr/content/download/33852/575120/file/Reacteurs-generation-4-CEA.pdf |archive-date=3 June 2012}}</ref> {{as of|2013}} the UK had shown interest in the [[PRISM (reactor)|PRISM]] reactor and was working in concert with France to develop ASTRID. In 2019, [[French Alternative Energies and Atomic Energy Commission|CEA]] announced this design would not be built before mid-century.<ref>{{cite news |title=France drops plans to build sodium-cooled nuclear reactor |work=Reuters |language=en |date=30 August 2019 |url=https://www.reuters.com/article/us-france-nuclearpower-astrid-idUSKCN1VK0MC |access-date=20 November 2019 |url-status=live |archive-url=https://web.archive.org/web/20190924151926/https://www.reuters.com/article/us-france-nuclearpower-astrid-idUSKCN1VK0MC |archive-date=24 September 2019}}</ref>

=== United States ===
Kirk Sorensen, former NASA scientist and chief nuclear technologist at [[Teledyne Brown Engineering]], has long been a promoter of thorium fuel cycle and particularly liquid fluoride thorium reactors. In 2011, Sorensen founded Flibe Energy, a company aimed to develop 20–50&nbsp;MW LFTR reactor designs to power military bases.<ref>{{cite web |title=Flibe Energy |url=http://flibe-energy.com/ |url-status=live |archive-url=https://web.archive.org/web/20130207043957/http://flibe-energy.com/ |archive-date=7 February 2013 |access-date=29 October 2011}}</ref><ref>{{cite web |date=23 May 2011 |title=Kirk Sorensen has started a Thorium Power company Flibe Energy |url=https://www.nextbigfuture.com/2011/05/kirk-sorensen-has-started-thorium-power.html |url-status=live |archive-url=https://web.archive.org/web/20111026201509/http://nextbigfuture.com/2011/05/kirk-sorensen-has-started-thorium-power.html |archive-date=26 October 2011 |access-date=30 October 2011 |publisher=The Next Bi Future}}</ref><ref>{{cite news |date=7 September 2001 |title=Live chat: nuclear thorium technologist Kirk Sorensen |url=https://www.theguardian.com/environment/blog/2011/sep/07/live-web-chat-nuclear-kirk-sorensen |url-status=live |archive-url=https://web.archive.org/web/20140715094622/http://www.theguardian.com/environment/blog/2011/sep/07/live-web-chat-nuclear-kirk-sorensen |archive-date=15 July 2014 |access-date=30 October 2011 |work=Environment Blog |publisher=The Guardian (UK) |location=London}}</ref><ref>{{cite web |last=Martin |first=William T. |date=27 September 2011 |title=New Huntsville company to build thorium-based nuclear reactors |url=http://www.huntsvillenewswire.com/2011/09/27/huntsville-company-build-thoriumbased-nuclear-reactors/ |url-status=usurped |archive-url=https://web.archive.org/web/20120406184105/http://www.huntsvillenewswire.com/2011/09/27/huntsville-company-build-thoriumbased-nuclear-reactors/ |archive-date=6 April 2012 |access-date=30 October 2011 |publisher=Huntsville Newswire}}</ref>

In October 2010 [[GE Hitachi Nuclear Energy]] signed a [[memorandum of understanding]] with the operators of the [[United States Department of Energy|US Department of Energy's]] [[Savannah River Site]], which should allow the construction of a demonstration plant based on the company's [[S-PRISM]] fast breeder reactor prior to the design receiving full [[Nuclear Regulatory Commission]] licensing approval.<ref name="wnn281010">{{cite news |title=Prototype Prism proposed for Savannah River |work=World Nuclear News |date=28 October 2010 |url=http://www.world-nuclear-news.org/NN-Prototype_Prism_proposed_for_Savannah_River-2810104.html |access-date=4 November 2010 |url-status=live |archive-url=https://web.archive.org/web/20190128080359/http://www.world-nuclear-news.org/NN-Prototype_Prism_proposed_for_Savannah_River-2810104.html |archive-date=28 January 2019}}</ref> In October 2011 ''[[The Independent]]'' reported that the UK Nuclear Decommissioning Authority (NDA) and senior advisers within the Department for Energy and Climate Change (DECC) had asked for technical and financial details of PRISM, partly as a means of reducing the country's plutonium stockpile.<ref>{{cite news |title=New life for old idea that could dissolve our nuclear waste |work=The Independent |location=London |first=Steve |last=Connor |date=28 October 2011 |url=https://www.independent.co.uk/environment/green-living/new-life-for-old-idea-that-could-dissolve-our-nuclear-waste-2376882.html |access-date=30 October 2011 |url-status=live |archive-url=https://web.archive.org/web/20111029131943/http://www.independent.co.uk/environment/green-living/new-life-for-old-idea-that-could-dissolve-our-nuclear-waste-2376882.html |archive-date=29 October 2011}}</ref>

The [[traveling wave reactor]] proposed in a patent by [[Intellectual Ventures]] is a fast breeder reactor designed to not need fuel reprocessing during the decades-long lifetime of the reactor. The breed-burn wave in the TWR design does not move from one end of the reactor to the other but gradually from the inside out. Moreover, as the fuel's composition changes through nuclear transmutation, fuel rods are continually reshuffled within the core to optimize the neutron flux and fuel usage at any given point in time. Thus, instead of letting the wave propagate through the fuel, the fuel itself is moved through a largely stationary burn wave. This is contrary to many media reports, which have popularized the concept as a candle-like reactor with a burn region that moves down a stick of fuel. By replacing a static core configuration with an actively managed "standing wave" or "soliton" core, [[TerraPower]]'s design avoids the problem of cooling a highly variable burn region. Under this scenario, the reconfiguration of fuel rods is accomplished remotely by robotic devices; the containment vessel remains closed during the procedure, and there is no associated downtime.<ref>{{cite magazine |title=TR10: Traveling Wave Reactor |magazine=Technology Review |date=March 2009 |url=http://www.technologyreview.com/energy/22114/ |access-date=6 March 2009 |url-status=live |archive-url=https://web.archive.org/web/20120504090500/http://www.technologyreview.com/energy/22114/ |archive-date=4 May 2012}}</ref>

==See also==
{{Portal|Energy|Nuclear technology}}

* [[Nuclear fusion–fission hybrid]]

==References==
{{Reflist}}

==External links==
*{{cite web |language=en |title=Fast Neutron Reactor Plants From Experience to Prospects |url=http://www.okbm.nnov.ru/upload/iblock/4d4/4d41c798e50dc6bba66c28a66d02505d.pdf |access-date=29 November 2019 |url-status=dead |archive-url=https://web.archive.org/web/20200801083615/http://www.okbm.nnov.ru/upload/iblock/4d4/4d41c798e50dc6bba66c28a66d02505d.pdf |archive-date=1 August 2020}} – on [[OKBM Afrikantov]] official pdf{{in lang|en}}
*[https://web.archive.org/web/20160125131513/http://www.nationalcenter.org/NPA378.html Breeder terminology]
*[https://www.nrc.gov/reading-rm/doc-collections/nuregs/staff/sr1350/index.html Information Digest, 2022–2023 (NUREG-1350, Volume 34)], NRC
*[https://web.archive.org/web/20110726163836/http://www-frdb.iaea.org/index.html IAEA Fast Reactors Database]
*[https://web.archive.org/web/20080618221141/http://www.iaea.org/inis/aws/fnss/abstracts/index.html IAEA Technical Documents on Fast Reactors]
*[https://www.ne.anl.gov/About/reactors/frt.shtml Reactors Designed by Argonne National Laboratory: Fast Reactor Technology] Argonne pioneered the development of fast reactors and is a leader in the development of fast reactors worldwide. See also [https://www.ne.anl.gov/About/legacy/ Argonne's Nuclear Science and Technology Legacy].
*[https://web.archive.org/web/20130311145213/http://www.atomicheritage.org/ebr1.htm Atomic Heritage Foundation – EBR-I]
*[http://large.stanford.edu/publications/coal/references/docs/wilson.pdf The Changing Need for a Breeder Reactor] by Richard Wilson at The Uranium Institute 24th Annual Symposium, September 1999
*[http://www.ans.org/store/vi-300032 Experimental Breeder Reactor-II (EBR-II): An Integrated Experimental Fast Reactor Nuclear Power Station]
*[http://www.thoriumenergyworld.com/ International Thorium Energy Organisation – www.IThEO.org]
*[https://lmfbr.com/ A Path Forward for the LMFBR]
* {{YouTube|aI8VyCZlkwA|''Plutonium Fuel Fabrication'' by Argonne National Laboratory}}

{{Nuclear fission reactors}}

{{Authority control}}

[[Category:Nuclear power reactor types]]