Editing Integral fast reactor (section)

==Comparisons to light-water reactors==
[[File:Sasahara.svg|thumb|Transmutation flow between <sup>238</sup>[[Plutonium-238|Pu]] and <sup>244</sup>[[Curium-244|Cm]] in a LWR.<ref>{{cite journal|title=Neutron and Gamma Ray Source Evaluation of LWR High Burn-up UO2 and MOX Spent Fuels|journal=Journal of Nuclear Science and Technology|volume=41|issue=4|pages=448–456|date=April 2004|doi=10.3327/jnst.41.448|author=Sasahara, Akihiro|last2=Matsumura|first2=Tetsuo|last3=Nicolaou|first3=Giorgos|last4=Papaioannou|first4=Dimitri|doi-access=free}}</ref> Current thermal-neutron fission reactors cannot fission actinide nuclides that have an even number of neutrons. Thus, these build up and are generally treated as [[transuranic waste]] after conventional reprocessing. An argument for fast reactors is that they can fission all actinides.|360x360px]]

===Nuclear waste===
The waste products of IFR reactors either have a short half-life, which means that they decay quickly and become relatively safe, or a long half-life, which means that they are only slightly radioactive. Neither of the two forms of IFR waste produced contain plutonium or other [[actinides]]. Due to pyroprocessing, the total volume of true waste/[[fission products]] is 1/20th the volume of spent fuel produced by a light-water plant of the same power output, and is often considered to be all unusable waste. 70% of fission products are either stable or have half-lives under one year. [[Technetium-99]] and [[iodine-129]], which constitute 6% of fission products, have very long half-lives but can be [[Nuclear transmutation|transmuted]] to isotopes with very short half-lives (15.46 seconds and 12.36 hours) by neutron absorption within a reactor, effectively destroying them (see more: [[long-lived fission product]]s). [[Isotopes of zirconium|Zirconium-93]], another 5% of fission products, could in principle be recycled into fuel-pin cladding, where it does not matter that it is radioactive. Excluding the contribution from [[transuranic waste]] (TRU) – which are isotopes produced when [[uranium-238]] captures a slow [[thermal neutron]] in an LWR but does not fission – all [[high level waste]]/fission products remaining after reprocessing the TRU fuel is less radiotoxic (in [[sievert]]s) than [[natural uranium]] (in a gram-to-gram comparison) within 200–400 years, and continues to decline afterward.<ref>{{cite web |url=https://www.youtube.com/watch?v=UA5sxV5b5b4 |archive-url=https://ghostarchive.org/varchive/youtube/20211212/UA5sxV5b5b4| archive-date=2021-12-12 |url-status=live|title=Dealing with the Used Fuel (Reprocessing)|author=Professor David Ruzic|website=[[YouTube]] |date=14 May 2019 }}{{cbignore}}</ref><ref name="pg 15 see SV/g chart">{{cite journal|url=http://www.stralsakerhetsmyndigheten.se/Global/Publikationer/Tidskrift/Nucleus/2007/Nucleus-4-2007.pdf |title=Återanvändning av lång sluten bränslecykel möj |journal=Nucleus |author=Janne Wallenius |date=2007-04-01 |page=15 |url-status=dead |archive-url=https://web.archive.org/web/20140519002715/http://www.stralsakerhetsmyndigheten.se/Global/Publikationer/Tidskrift/Nucleus/2007/Nucleus-4-2007.pdf |archive-date=2014-05-19 }}</ref><ref name="berkeley" />{{Unreliable source?|date=July 2012}}<ref name="https"/>{{better source|date=July 2014}}
<!--
Edwin Sayre has estimated that a ton of fission products (which includes the very weakly radioactive [[palladium-107]]), when reduced to metal, has a market value of $16 million.<ref>[http://brc.gov/e-mails/August10/Commercial Value of 1 Metric ton of used fuel.pdf]{{Dead link|date=July 2012}}</ref>--><!--This source pdf has been lost. No backup on Wayback Machine. Internet search yields some identical references, but no source. Cannot verify.-->

The on-site reprocessing of fuel means that the volume of high-level nuclear waste leaving the plant is tiny compared to LWR spent fuel.{{NoteTag|Estimates from Argonne National Laboratory place the output of waste of a 1,000&nbsp;[[MWe]] plant operating at 70% capacity at 1,700&nbsp;pounds/year.<ref name="berkeley" />}} In fact, in the U.S. most spent LWR fuel has remained in storage at the reactor site instead of being transported for reprocessing or placement in a [[geological repository]]. The smaller volumes of [[high level waste]] from reprocessing could stay at reactor sites for some time, but are intensely radioactive from [[medium-lived fission products]] (MLFPs) and need to be stored securely, like in [[dry cask storage]] vessels. In its first few decades of use, before the MLFPs decay to lower levels of heat production, geological repository capacity is constrained not by volume but by heat generation. This limits early repository emplacement. [[Decay heat]] generation of MLFPs from IFRs is about the same per unit power as from any kind of fission reactor.

The potential complete removal of plutonium from the waste stream of the reactor reduces the concern that now exists with spent nuclear fuel from most other reactors, namely that a spent fuel repository could be used as a [[Radioactive waste#Proliferation concerns|plutonium mine]] at some future date.{{sfnp|U.S. Congress|1994|p=30}} Also, despite the million-fold reduction in radiotoxicity offered by this scheme,{{NoteTag|Radioactivity and its associated dangers are roughly divided by an isotope's half-life. For example, given the 213,000-year half-life of technetium-99, combined with the IFR's 1/20 volume reduction, produces about 1/4,000,000 of the radiotoxicity of light-water reactor waste. The small size (about 1.5 tonnes per gigawatt-year) permits expensive disposal methods such as insoluble synthetic rock. The hazards are far less than those from fossil fuel wastes or dam failures.}} there remain concerns about radioactive longevity:<blockquote>[Some believe] that actinide removal would offer few if any significant advantages for disposal in a [[geologic repository]] because some of the ''fission product'' [sic] [[nuclide]]s of greatest concern in scenarios such as [[Leaching (chemical science)|leaching]] into [[groundwater]] actually have longer half-lives than the radioactive actinides. The concern about a waste cannot end after hundreds of years even if all the actinides are removed when the remaining waste contains radioactive fission products such as technetium-99, iodine-129, and cesium-135 with the half-lives between 213,000 and 15.7 million years.{{sfnp|U.S. Congress|1994|p=30}}</blockquote>However, these concerns do not consider the plan to store such materials in insoluble [[Synroc]], and do not measure hazards in proportion to those from natural sources such as medical [[x-ray]]s, [[cosmic ray]]s, or naturally radioactive rocks (such as [[granite]]).{{Citation needed|date=July 2024}} Furthermore, some of the radioactive fission products are being targeted for [[Nuclear transmutation|transmutation]], belaying even these comparatively low concerns. For example, the IFR's positive [[void coefficient]] could be reduced to an acceptable level by adding technetium to the core, helping destroy the long-lived fission product [[technetium-99]] by [[nuclear transmutation]] in the process.<ref name="osti.gov">[http://www.osti.gov/bridge/servlets/purl/10171782-o1Ys0R/10171782.pdf Reduction of the Sodium-Void Coefficient of Reactivity by Using a Technetium Layer] page 2</ref>

===Carbon dioxide===
{{Main|Life-cycle greenhouse-gas emissions of energy sources}}
Both IFRs and LWRs do not emit [[Carbon dioxide|CO<sub>2</sub>]] during operation, although construction and fuel processing result in CO<sub>2</sub> emissions (if via energy sources which are not carbon neutral, such as fossil fuels) and CO<sub>2</sub>-emitting cements are used in the construction process.

A 2012 [[Yale University]] review 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 [[Generation III reactor]]s presently under construction, it did summarize the LCA findings of in-development reactor technologies:

{{Quote|Theoretical FBRs {{bracket|[[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 {{bracket|[[light water reactor]]s}} and purports to consume little or no [[uranium market|uranium ore]].}}

{{Actinidesvsfissionproducts}}

===Fuel cycle===
{{see also|Nuclear fuel cycle}}
[[Fast reactor]] fuel must be at least 20% fissile, greater than the [[low enriched uranium|low-enriched uranium]] used in LWRs. The [[fissile]] material can initially include [[highly enriched uranium]] or [[plutonium]] from LWR [[spent fuel]], decommissioned [[nuclear weapon]]s, or other sources. During operation, the reactor breeds more fissile material from [[fertile material]] – at most about 5% more from uranium and 1% more from [[thorium]].

The fertile material in fast reactor fuel can be [[depleted uranium]] (mostly [[uranium-238]]), [[natural uranium]], [[thorium]], or [[reprocessed uranium]] from [[spent fuel]] from traditional LWRs,<ref name=berkeley/> and even include nonfissile [[isotopes of plutonium]] and [[minor actinide]] isotopes. Assuming no leakage of actinides to the waste stream during reprocessing, a 1 GWe IFR-style reactor would consume about 1 ton of fertile material per year and produce about 1 ton of [[fission product]]s.

[[nuclear reprocessing#PYRO-A and -B for IFR|The IFR fuel cycle's reprocessing]] by [[pyroprocessing]] (in this case, [[electrorefining]]) does not need to produce pure plutonium, free of fission product radioactivity, as the [[PUREX]] process is designed to do. The purpose of reprocessing in the IFR fuel cycle is simply to reduce the level of those fission products that are [[neutron poison]]s; even these need not be completely removed. The electrorefined spent fuel is highly radioactive, but because new fuel need not be precisely fabricated like LWR fuel pellets but can simply be cast, remote fabrication can be used, reducing exposure to workers.

Like any fast reactor, by changing the material used in the blankets, the IFR can be operated over a spectrum from breeder to self-sufficient to burner. In breeder mode (using U-238 blankets) the reactor produces more fissile material than it consumes. This is useful for providing fissile material for starting up other plants. Using steel reflectors instead of U-238 blankets, the reactor operates in pure burner mode and is not a net creator of fissile material; on balance, it will consume fissile and fertile material and, assuming loss-free reprocessing, output no [[actinides]] but only [[fission products]] and [[activation products]]. The amount of fissile material needed could be a limiting factor to very widespread deployment of fast reactors if stocks of surplus weapons plutonium and LWR spent fuel plutonium are not sufficient. To maximize the rate at which fast reactors can be deployed, they can be operated in maximum breeding mode.

Reprocessing nuclear fuel using pyroprocessing and electrorefining has not yet been demonstrated on a commercial scale, so investing in a large IFR-style plant may be a higher [[financial risk]] than a conventional LWR.

===Passive safety===
[[File:Ifr concept.jpg|thumb|upright=1.5|IFR concept (color); an animation of the pyroprocessing cycle is also available.<ref>{{cite web |url=https://www.youtube.com/watch?v=cBThTwFhRlA |archive-url=https://ghostarchive.org/varchive/youtube/20211212/cBThTwFhRlA| archive-date=2021-12-12 |url-status=live|title=Historical video about the Integral Fast Reactor (IFR) concept. Uploaded by – Nuclear Engineering at Argonne|website=[[YouTube]] |date=3 March 2014 }}{{cbignore}}</ref>]]
[[File:IFR concept.png|thumb|upright=1.5|IFR concept (black and white with clearer text)]]

The IFR uses metal alloy fuel (uranium, plutonium, and/or zirconium), which is a good conductor of heat, unlike the [[uranium oxide]] used by LWRs (and even some fast breeder reactors), which is a poor conductor of heat and reaches high temperatures at the center of fuel pellets. The IFR also has a smaller volume of fuel, since the fissile material is diluted with fertile material by a ratio of 5 or less, compared to about 30 for LWR fuel. The IFR core requires more heat removal per core volume during operation than the LWR core; but on the other hand, after a shutdown, there is far less trapped heat that is still diffusing out and needs to be removed. However, [[decay heat]] generation from short-lived fission products and actinides is comparable in both cases, starting at a high level and decreasing with time elapsed after shutdown. The high volume of liquid sodium primary coolant in the pool configuration is designed to absorb decay heat without reaching fuel melting temperature. The primary sodium pumps are designed with [[flywheel]]s so they will coast down slowly (90 seconds) if power is removed. This coast-down further aids core cooling upon shutdown. If the primary cooling loop were to be somehow suddenly stopped, or if the control rods were suddenly removed, the metal fuel can melt, as accidentally demonstrated in EBR-I; however, the melting fuel is then extruded up the steel fuel cladding tubes and out of the active core region leading to permanent reactor shutdown and no further fission heat generation or fuel melting.<ref name=TillAndYang>{{cite book|last=Till and Chang|first=Charles E. and Yoon Il|title=Plentiful Energy: The Story of the Integral Fast Reactor|year=2011|publisher=CreateSpace|isbn=978-1466384606|pages=157–158|url=http://www.sustainablenuclear.org/PADs/pad0509till.html|access-date=2011-06-23|archive-url=https://web.archive.org/web/20110605030654/http://www.sustainablenuclear.org/PADs/pad0509till.html|archive-date=2011-06-05|url-status=dead}}</ref> With metal fuel, the cladding is not breached and no radioactivity is released even in extreme overpower transients.

Self-regulation of the IFR's power level depends mainly on thermal expansion of the fuel, which allows more neutrons to escape, damping the [[chain reaction]]. LWRs have less effect from thermal expansion of fuel (since much of the core is the [[neutron moderator]]) but have strong [[negative feedback]] from [[Doppler broadening]] (which acts on thermal and epithermal neutrons, not fast neutrons) and negative [[void coefficient]] from boiling of the water moderator/coolant; the less dense steam returns fewer and less-thermalized neutrons to the fuel, which are more likely to be captured by U-238 than induce fissions. However, the IFR's positive void coefficient could be reduced to an acceptable level by adding technetium to the core, helping destroy the [[long-lived fission product]] named [[technetium-99]] by [[nuclear transmutation]] in the process.<ref name="osti.gov"/>

IFRs are able to withstand both a loss of flow without [[SCRAM]] and loss of heat sink without SCRAM. In addition to the passive shutdown of the reactor, the convection current generated in the primary coolant system will prevent fuel damage (core meltdown). These capabilities were demonstrated in the [[EBR-II]].<ref name="ANL" /> The ultimate goal is that no radioactivity is released under any circumstance.

The flammability of sodium is a risk to operators. Sodium burns easily in air and will ignite spontaneously on contact with water. The use of an intermediate coolant loop between the reactor and the turbines minimizes the risk of a sodium fire in the reactor core.

Under neutron bombardment, [[sodium-24]] is produced. This is highly radioactive, emitting an energetic [[gamma ray]] of 2.7 [[Electronvolt|MeV]] followed by a [[beta decay]] to form [[magnesium-24]]. Half-life is only 15 hours, so this isotope is not a long-term hazard. Nevertheless, the presence of sodium-24 further necessitates the use of the intermediate coolant loop between the reactor and the turbines.

===Proliferation===
{{See also|reactor grade plutonium}}
IFRs and [[light-water reactor]]s (LWRs) both produce [[reactor grade plutonium]] – which even at high [[burnup]]s remains weapons-usable<ref>[https://www.belfercenter.org/sites/default/files/files/publication/mmup.pdf Managing Military Uranium and Plutonium in the United States and the Former Soviet Union], Matthew Bunn and John P. Holdren, Annu. Rev. Energy Environ. 1997. 22:403–86</ref> – but the IFR fuel cycle has some design features that make proliferation more difficult than the current [[PUREX]] recycling of spent LWR fuel. For one thing, it may operate at higher burnups and therefore increase the relative abundance of the non-fissile, but fertile, isotopes [[plutonium-238]], [[plutonium-240]], and [[plutonium-242]].<ref>[http://info.ornl.gov/sites/publications/Files/Pub37993.pdf Categorization of Used Nuclear Fuel Inventory in Support of a Comprehensive National Nuclear Fuel Cycle Strategy]. page 35 figure 21. Discharge isotopic composition of a [[pressurized water reactor]] fuel assembly with initial U-235 enrichment of 4.5 wt % that has accumulated 45 GWd/MTU burnup. Isotopic composition of used nuclear fuel as a function of burnup for a generic PWR fuel assembly.</ref>

Unlike PUREX reprocessing, the IFR's electrolytic reprocessing of [[spent fuel]] does not separate out pure plutonium. Instead, it is left mixed with minor actinides and some rare earth fission products, which makes the theoretical ability to make a bomb directly out of it considerably dubious.<ref name="youtube.com"/>{{better source|date=July 2014}} Rather than being transported from a large centralized reprocessing plant to reactors at other locations – as is common now in France, from [[La Hague]] to its dispersed nuclear fleet of LWRs – the IFR pyroprocessed fuel would be much more resistant to unauthorized diversion.<ref name="ReferenceB"/>{{better source|date=July 2014}} The material with the mix of [[plutonium isotopes]] in an IFR would stay at the reactor site and then be burnt up practically ''in-situ'';<ref name="ReferenceB"/>{{better source|date=July 2014}} alternatively, if operated as a breeder reactor, some of the pyroprocessed fuel could be consumed by the reactor (or other reactors located elsewhere). However, as is the case with conventional aqueous reprocessing, it would remain possible to chemically extract all the plutonium isotopes from the pyroprocessed fuel. In fact, it would be much easier to do so from the recycled product than from the original spent fuel. However, doing so would still be more difficult when compared to another conventional recycled nuclear fuel, [[MOX]], as the IFR recycled fuel contains more fission products and, due to its higher [[burnup]], more proliferation-resistant [[Pu-240]] than MOX.

An advantage to the removal and burn up of actinides (include plutonium) from the IFR's spent fuel is the elimination of concerns about leaving spent fuel (or indeed conventional – and therefore comparatively lower [[burnup]] – spent fuel, which can contain weapons-usable plutonium isotope concentrations) in a [[geological repository]] or [[dry cask storage]], which could be mined in the future for the purpose of making weapons.{{sfnp|U.S. Congress|1994|p=30}}

Because reactor-grade plutonium contains isotopes of plutonium with high [[spontaneous fission]] rates, and the ratios of these troublesome isotopes (from a weapons manufacturing point of view) only increases{{Confusing-inline|reason=How can an *increase* in the Pu isotope ratio make the spent fuel more difficult to use for weapons? This seems backwards. Wouldn't more burnup imply less usable Pu for weapons?|date=July 2024}} as the fuel is burnt up for longer and longer, it is considerably more difficult to produce fission nuclear weapons of substantial yield from highly burnt up spent fuel than from (conventional) moderately burnt up LWR spent fuel.

Therefore, proliferation risks are considerably reduced with the IFR system by many metrics, but not entirely eliminated. The plutonium from advanced liquid metal reactor (ALMR) recycled fuel would have an isotopic composition similar to that obtained from other highly burnt up [[spent nuclear fuel]] sources. Although this makes the material less attractive for weapons production, it could nonetheless be used in less sophisticated weapons or with [[fusion boosting]].

In 1962, the U.S. government detonated a nuclear device using then-defined "[[reactor-grade plutonium]]", although in more recent categorizations it would instead be considered as [[reactor grade plutonium#Classification by isotopic composition|fuel-grade plutonium]], typical of that produced by low burn up [[Magnox reactor]]s.<ref>{{cite web |author=WNA <!--contributors --> |url=http://www.world-nuclear.org/info/inf15.html |title=Plutonium |publisher=World Nuclear Association |date=March 2009 |access-date=2010-02-28 |archive-date=2010-03-30 |archive-url=https://web.archive.org/web/20100330221426/http://www.world-nuclear.org/info/inf15.html |url-status=dead }}</ref>{{sfnp|U.S. Congress|1994|p=34}}

Plutonium produced in the fuel of a breeder reactor generally has a higher fraction of the isotope [[plutonium-240]] than that produced in other reactors, making it less attractive for weapons use, particularly in first-generation [[nuclear weapon design]]s similar to [[Fat Man]]. This offers an intrinsic degree of proliferation resistance. However, if a blanket of uranium is used to surround the core during breeding, the plutonium made in the blanket is usually of a high [[Pu-239]] quality, containing very little Pu-240, making it highly attractive for weapons use.<ref>https://www.fas.org/nuke/intro/nuke/plutonium.htmBreeder reactors {{Webarchive|url=https://web.archive.org/web/20130701133701/http://www.fas.org/nuke/intro/nuke/plutonium.htm |date=2013-07-01 }}</ref>

If operated as a breeder instead of a burner, the IFR has proliferation potential:<blockquote>Although some recent proposals for the future of the ALMR/IFR concept have focused more on its ability to transform and irreversibly use up plutonium, such as the conceptual [[PRISM (reactor)]] and the in operation (2014) [[BN-800 reactor]] in Russia, the developers of the IFR acknowledge that it is 'uncontested that the IFR can be configured as a net producer of plutonium'.{{sfnp|U.S. Congress|1994|p=32}}

If instead of processing spent fuel, the ALMR system were used to reprocess ''irradiated [[fertile material|fertile (breeding) material]]'' [that is, if a blanket of breeding U-238 was used] in the electrorefiner, the resulting plutonium would be a superior material, with a nearly ideal isotope composition for nuclear weapons manufacture.{{sfnp|U.S. Congress|1994|p=36}}</blockquote>

===Reactor design and construction===
A commercial version of the IFR, [[S-PRISM]], can be built in a factory and transported to the site. This [[small modular reactor|small modular]] design (311 MWe modules) reduces costs and allows nuclear plants of various sizes (311 MWe and any integer multiple) to be economically constructed.

Cost assessments taking account of the complete life cycle show that fast reactors could be no more expensive than water-moderated water-cooled reactors, currently the most widely used reactors in the world.<ref>{{cite journal|title=BN-800 as a New Stage in the Development of Fast Sodium-Cooled Reactors |date=2004-06-01 |doi=10.1023/B:ATEN.0000041204.70134.20 |volume=96 |issue=6 |journal=Atomic Energy |pages=386–390|last1=Poplavskii |first1=V. M. |last2=Chebeskov |first2=A. N. |last3=Matveev |first3=V. I. |s2cid=96585192 }}</ref>

===Liquid metal sodium coolant===
{{See also|BN-600 reactor}}
Unlike reactors that use relatively slow low energy (thermal) neutrons, [[fast-neutron reactor]]s need [[nuclear reactor coolant]] that does not moderate or block neutrons (like water does in an LWR) so that they have sufficient energy to fission [[actinide]] isotopes that are [[fissionable]] but not [[fissile]]. The core must also be compact and contain the least amount of neutron-moderating material as possible. Metal sodium coolant in many ways has the most attractive combination of properties for this purpose. In addition to not being a neutron moderator, desirable physical characteristics include:

* Low melting temperature
* Low vapor pressure
* High boiling temperature
* Excellent thermal conductivity
* Low viscosity
* Light weight
* Thermal and radiation stability

Additional benefits to using liquid sodium include:

* Abundant and low-cost material
* Cleaning with chlorine produces non-toxic [[NaCl|table salt]]
* Compatible with other materials used in the core (does not react or dissolve stainless steel), so no special corrosion protection measures are needed
* Low pumping power (from lightweight and low viscosity)
* Protects other components from corrosion by maintaining an oxygen- and water-free environment (sodium would react with any trace amounts to make sodium oxide or sodium hydroxide and hydrogen)
* Lightweight (low density) improves resistance to seismic inertia events (earthquakes)

Significant drawbacks to using sodium are its extreme fire hazardousness in the presence of any significant amounts of air (oxygen) and its spontaneous combustion with water, rendering sodium leaks and flooding dangerous. This was the case at the [[Monju Nuclear Power Plant]] in a 1995 accident and fire. Reactions with water produce hydrogen which can be explosive. The sodium activation product (isotope) <sup>24</sup>Na releases dangerous energetic photons when it decays (albeit having only short half-life of 15 hours). The reactor design keeps <sup>24</sup>Na in the reactor pool and carries away heat for power production using a secondary sodium loop, but this adds costs to construction and maintenance.<ref>{{cite web |last=Fanning |first=Thomas H. |date=May 3, 2007 |title=Sodium as a Fast Reactor Coolant |url=http://www.ne.doe.gov/pdfFiles/SodiumCoolant_NRCpresentation.pdf |url-status=dead |archive-url=https://web.archive.org/web/20130113134710/http://www.ne.doe.gov/pdfFiles/SodiumCoolant_NRCpresentation.pdf |archive-date=2013-01-13 |access-date=2014-01-24 |website=Ne.doe.gov |publisher= |institution=Office of Nuclear Energy &#124; Department of Energy &#124; University of Chicago, [[Argonne National Laboratory|Argonne]]}}</ref>