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'''Reactor-grade plutonium (RGPu)'''<ref name="web.archive.org">[https://web.archive.org/web/20170711002254/http://dfat.gov.au/about-us/publications/Pages/the-categorisation-of-nuclear-material-in-the-context-of-integrated-safeguards.aspx The categorisation of nuclear material in the context of integrated safeguards]</ref><ref>[https://www.iaea.org/NuclearPower/Downloadable/Meetings/2016/2016-10-31-11-03-NPTDS/17_Abdul_Waris.pdf Plutonium Utilization in several MSR Designs. 2016]</ref> is the isotopic grade of plutonium that is found in [[spent nuclear fuel]] after the [[uranium-235]] primary fuel that a nuclear [[nuclear reactor|power reactor]] uses has [[burnup|burnt up]]. The [[uranium-238]] from which most of the [[isotopes of plutonium|plutonium isotope]]s derive by [[neutron capture]] is found along with the U-235 in the [[low enriched uranium]] fuel of civilian reactors.

In contrast to the low burnup of weeks or months that is commonly required to produce [[weapons-grade plutonium]] (WGPu/[[plutonium-239|<sup>239</sup>Pu]]), the long time in the reactor that produces reactor-grade plutonium leads to [[nuclear transmutation|transmutation]] of much of the [[fissile]], relatively long [[half-life]] isotope [[plutonium-239|<sup>239</sup>Pu]] into a number of other [[isotopes of plutonium]] that are less fissile or more radioactive. When {{chem|239|Pu}} absorbs a neutron, it does not always undergo [[nuclear fission]]. Sometimes [[neutron absorption]] will instead produce {{chem|240|Pu}} at the [[neutron temperature]]s and fuel compositions present in typical [[light water reactor]]s, with the concentration of {{chem|240|Pu}} steadily rising with longer irradiation, producing lower and lower grade plutonium as time goes on.

Generation II [[thermal-neutron reactor]]s (today's most numerous [[nuclear power station]]s) can reuse reactor-grade plutonium only to a limited degree as [[MOX fuel]], and only for a second cycle. [[Fast-neutron reactor]]s, of which there are a handful operating today with a half dozen under construction, can use reactor-grade plutonium fuel as a means to reduce the [[transuranium]] content of [[spent nuclear fuel]]/nuclear waste. Russia has also produced a new type of [[Remix fuel]] that directly recycles reactor grade plutonium at 1% or less concentration into fresh or re-enriched uranium fuel imitating the 1% plutonium level of high-burnup fuel.

==Classification by isotopic composition==

{| class="wikitable" align="right"
!     !!<1976  !!>1976
|-
|<7%  ||colspan="2" align="center"|Weapons grade
|-
|7-19%||rowspan="2" align="center"|Reactor grade||border="1px"|Fuel grade
|-
|>19% ||colspan="2" align="center"|Reactor grade
|}

At the beginning of the industrial scale production of plutonium-239 in war era ''[[nuclear reactor|production reactors]]'', trace contamination or co-production with [[plutonium-240]] was initially observed, with these trace amounts resulting in the dropping of the [[Thin Man (nuclear bomb)|Thin Man]] weapon-design as unworkable.<ref>{{Cite web | url=http://www.chemcases.com/2003version/nuclear/nc-09.htm | title=Nuclear Chemistry - the First Atomic Bombs| archive-url=https://web.archive.org/web/20120301130234/http://www.chemcases.com/2003version/nuclear/nc-09.htm| archive-date=2012-03-01}}</ref> The difference in purity, of how much, continues to be important in assessing significance in the context of [[nuclear proliferation]] and weapons-usability.
[[File:Sasahara.svg|thumb|400px|Percentages are of each [[nuclide]]'s total [[nuclear transmutation|transmutation]] rate in a [[Light-water reactor|LWR]], which is low for many non[[fissile]] [[actinide]]s. After leaving reactor only decay occurs.]] 
The [[United States Department of Energy|DOE]] definition of ''reactor grade'' [[plutonium]] changed in 1976. Before this, three grades were recognised. The change in the definition for ''reactor grade'', from describing plutonium with greater than 7% [[Plutonium-240|Pu-240]] content prior to 1976, to  ''reactor grade'' being defined as containing 19% or more Pu-240, coincides with the 1977 release of information about a 1962 "''reactor grade'' nuclear test". The question of which definition or designation applies, that of the old or new scheme, to the 1962 "reactor-grade" test, has not been officially disclosed.

*'''[[Plutonium-239#Supergrade plutonium|Super weapons grade]]''', less than 3% [[Plutonium-240|Pu-240]],
*'''[[Weapons grade]]''', less than 7% Pu-240 and
*'''Reactor grade''', 7% or more Pu-240.
From 1976, four grades were recognised:
*'''Super weapons grade''', less than 3% [[Plutonium-240|Pu-240]]
*'''Weapons grade''', less than 7% Pu-240,
*'''Fuel grade''', 7% to 19% Pu-240 and
*'''Reactor grade''', more than 19% Pu-240.<ref name="fas">{{cite web |url=https://www.fas.org/nuke/intro/nuke/plutonium.htm |title=Plutonium Production - Nuclear Weapons |access-date=2013-07-03 |url-status=dead |archive-url=https://web.archive.org/web/20130701133701/http://www.fas.org/nuke/intro/nuke/plutonium.htm |archive-date=2013-07-01 }}</ref>

[[nuclear reprocessing|Reprocessing]] or recycling of the [[spent fuel]] from the most common class of civilian-electricity-generating or ''power reactor'' design, the [[Light-water reactor|LWR]], (with examples being the [[pressurized water reactor|PWR]] or [[boiling water reactor|BWR]]) recovers ''reactor grade'' plutonium (as defined since 1976), not ''fuel grade''.<ref name="info.ornl.gov">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 34 figure 20. Discharge isotopic composition of a WE 17×17 assembly with initial enrichment of 4.5 wt % that has accumulated 45&nbsp;GWd/tU burnup/</ref><ref name="fas.org">https://fas.org/nuke/intro/nuke/plutonium.htm {{Webarchive|url=https://web.archive.org/web/20090203203853/http://www.fas.org/nuke/intro/nuke/plutonium.htm |date=2009-02-03 }} Source: Plutonium Fuel - OECD Report, 1989</ref>

The physical mixture of isotopes in reactor-grade plutonium make it extremely difficult to handle and form and therefore explains its undesirability as a weapon-making substance, in contrast to weapons grade plutonium, which can be handled relatively safely with thick gloves.<ref name="fas" />

To produce [[weapons grade]] plutonium, the uranium nuclear fuel must spend no longer than several weeks in the reactor core before being removed, creating a low fuel [[burnup]]. For this to be carried out in a [[pressurized water reactor]] - the most common reactor design for electricity generation - the reactor would have to prematurely reach [[shutdown (nuclear reactor)|cold shut down]] after only recently being fueled, meaning that the reactor would need to cool [[decay heat]] and then have its [[reactor pressure vessel]] be depressurized, followed by a [[fuel rod]] defueling. If such an operation were to be conducted, it would be easily detectable,<ref name="fas" /><ref name="web.archive.org"/> and require prohibitively costly reactor modifications.<ref name="depletedcranium" />

One example of how this process could be detected in [[Pressurized water reactor|PWRs]], is that during these periods, there would be a considerable amount of down time, that is, large stretches of time that the reactor is not producing electricity to the grid.<ref>{{Cite web | url=http://www.ifpa.org/publications/MDRequirements2010/chapter4.php |title = Exploring U.S. Missile Defense Requirements in 2010 &#124; Chapter Four &#124; IFPA}}</ref> On the other hand, the modern definition of "reactor grade" plutonium is produced only when the reactor is run at high [[burnup]]s and therefore producing a high electricity generating [[capacity factor]]. According to the US Energy Information Administration (EIA), in 2009 the [[capacity factor]] of US nuclear power stations was higher than all other forms of energy generation, with nuclear reactors producing power approximately 90.3% of the time and Coal [[thermal power plant]]s at 63.8%, with down times being for simple routine maintenance and refuelling.<ref>[http://www.eia.gov/electricity/annual/archive/03482009.pdf Electric Power Annual 2009] Table 5.2 April 2011</ref>
[[File:Trinity crater (annotated) 2.jpg|thumb|left| An aerial photograph of the [[Trinity (nuclear test)]] crater shortly after the test. With an almost identical design to the [[Fat Man]] bomb used in Nagasaki, both used what now would be defined as ''[[X-10 Graphite Reactor|super weapons grade plutonium]]'',<ref>[https://web.archive.org/web/20120114081056/http://www.stealthskater.com/Documents/Nuke_08.pdf 8.0 The First Nuclear Weapons Version 2.17: 1 August 2002. CAREY SUBLETTE]</ref><ref>[https://web.archive.org/web/20171103153916/http://www.nuclearweaponarchive.org/Library/Plutonium/index.html Plutonium Manufacture and Fabrication]</ref> It employed a [[natural uranium]] tamper that contributed approximately 1/4 of the final explosive energy and in total released an estimated energy of 22 kiloton or 22,000 tons of [[TNT equivalent]].<ref group=note>The energy of the blast wave was [[Trinity (nuclear test)#Energy measurements|equivalent to that of 10 kiloton of TNT]], whereas the remaining ~12 kiloton of energy was emitted as nuclear radiations : X-ray, gamma, beta, nuclear fallout etc.</ref> The smaller crater in the southeast corner was from [[Trinity (nuclear test)#100-ton test|the earlier calibration test explosion]], that used a conventional mass of [[high explosive]]s of 0.1 kiloton or {{convert|108|tonTNT}}.]]
The degree to which typical [[Generation II reactor]] high [[burnup|burn-up]] produced reactor-grade plutonium is less useful than [[weapons-grade plutonium]] for building [[nuclear weapon]]s is somewhat debated, with many sources arguing that the maximum probable theoretical yield would be bordering on a [[Fizzle (nuclear test)|fizzle]] explosion of the range 0.1 to 2 [[kiloton]] in a [[Fat Man]] type device. As computations state that the energy yield of a nuclear explosive decreases by one and two [[orders of magnitude]] if the 240 Pu content increases from 5% (nearly weapons-grade plutonium) to 15%( 2 kt) and 25%,(0.2 kt) respectively.<ref name=":1">{{Cite journal|last=Şahin|first=Sümer|date=1981|title=Remarks On The Plutonium-240 Induced Pre-Ignition Problem In A Nuclear Device|url=http://www.ans.org/pubs/journals/download/a_32795|journal=Nuclear Technology|volume=54|issue=1|doi=10.13182/NT81-A32795|pages=431–432|quote=The energy yield of a nuclear explosive decreases by one and two orders of magnitude if the 240 Pu content increases from 5 (nearly weapons-grade plutonium) to 15 and 25%, respectively.|url-access=subscription}}</ref> These computations are theoretical and assume the non-trivial issue of dealing with the heat generation from the higher content of non-weapons usable [[Pu-238]] could be overcome.) As the premature initiation from the [[spontaneous fission]] of [[Pu-240]] would ensure a low explosive yield in such a device, the surmounting of both issues in the construction of an [[Improvised nuclear device]] is described as presenting "daunting" hurdles for a [[Fat Man]]-era implosion design, and the possibility of terrorists achieving this [[fizzle (nuclear test)|fizzle]] yield being regarded as an "overblown" apprehension with the safeguards that are in place.<ref>http://www.aps.org/units/fps/newsletters/2006/april/article2.html [[American Physical Society]] ''Bombs, Reprocessing, and Reactor Grade Plutonium''

Gerald E. Marsh and George S. Stanford</ref><ref name="depletedcranium">{{cite web|url=http://depletedcranium.com/why-you-cant-build-a-bomb-from-spent-fuel/ |title=Archived copy |access-date=2012-07-21 |url-status=dead |archive-url=https://web.archive.org/web/20120520124004/http://depletedcranium.com/why-you-cant-build-a-bomb-from-spent-fuel/ |archive-date=2012-05-20 }}</ref><ref name="aps.org">{{cite web |url=http://www.aps.org/units/fps/newsletters/1996/october/aoct96.html#a2 |title=American Physical Society Volume 25, Number 4 October 1996 ARTICLES, A Coverup of Nuclear Test Information? A. DeVolpi}}</ref><ref>{{cite web |url=http://www.nuclearfaq.ca/devolpi971121.htm |title=A letter (unpublished) from A. DeVolpi to Physics and Society. Published here with Dr. DeVolpi's permission. Response to "Usability of Reactor-grade Plutonium in Nuclear Weapons: A Reply to Alex DeVolpi" in Physics and Society, Vol 26(3) (10 July 1997): by A. DeVolpi, Woodridge, IL}}</ref><ref>[https://sciencetechnologyhistory.wordpress.com/article/nuclear-weapons-proliferation-outspoken-1gsyt5k142kc5-11/ NUCLEAR WEAPONS PROLIFERATION: Outspoken Opponents of Plutonium Demilitarization Delays and Missteps in Nuclear Demilitarization: Part 4.  Alexander DeVolpi, physicist (retired, Argonne National Laboratory); formerly manager of nuclear diagnostics and technical manager of arms control and nonproliferation program; author of Proliferation, Plutonium and Policy.]</ref><ref>http://www.phyast.pitt.edu/~blc/book/chapter13.html#1 Cohen. Chapter 13—THE NUCLEAR ENERGY OPTION  next=> PLUTONIUM AND BOMBS</ref>

Others disagree on theoretical grounds and state that while they would not be suitable for stockpiling or being emplaced on a missile for long periods of time, dependably high non-[[Fizzle (nuclear test)|fizzle]] level yields can be achieved,<ref name="J. Carson Mark">{{cite web |url=http://www.nci.org/NEW/NT/rgpu-mark-90.pdf |title=Reactor Grade Plutonium's Explosive Properties |author=J. Carson Mark |date=August 1990 |publisher=Nuclear Control Institute |access-date=May 10, 2010 |url-status=dead |archive-url=https://web.archive.org/web/20100508105622/http://www.nci.org/NEW/NT/rgpu-mark-90.pdf |archive-date=May 8, 2010 |author-link=J. Carson Mark }}</ref><ref>[http://fissilematerials.org International Panel on Fissile Materials], [http://fissilematerials.org/library/gfmr11.pdf Global Fissile Material Report 2011: Nuclear Weapon and Fissile Material Stockpiles and Production] (see Appendix 1), retrieved on October 1, 2012.</ref><ref>https://fas.org/rlg/980826-pu.htm [[Richard Lawrence Garwin]], Senior Fellow for Science and Technology, Council on Foreign Relations, New York, Draft of August 26, 1998</ref><ref>[https://web.archive.org/web/20160121172033/https://www.princeton.edu/sgs/publications/sgs/archive/17-2-3-Mark-vonHip-Lyman.pdf Explosive Properties of Reactor-Grade Plutonium, J. Carson Mark, Frank Von Hippel, Edward Lyman. Science and Global Security, 2009 DOI: 10.1080/08929880903368690]</ref><ref name="npolicy.org">{{Cite book |last=Jones |first=Gregory S. |url=https://npolicy.org/books/Reactor-Grade_Plutonium_and_Nuclear_Weapons/Greg%20Jones_Reactor-grade%20plutonium%20web.pdf |title=Reactor-Grade Plutonium and Nuclear Weapons: Exploding the Myths |date=2018-02-20 |publisher=Nonproliferation Policy Education Center |isbn=978-0986289590 |language=en |chapter=Chapter 3. The Different Kinds of Plutonium}}</ref><ref>[https://web.archive.org/web/20150814184434/http://www.iranwatch.org/sites/default/files/perspex-npec-lwr-102204.pdf Victor Gilinsky, Marvin Miller and Harmon Hubbard, “A Fresh Examination of the Proliferation Dangers of Light Water Reactors,” The Nonproliferation Policy Education Center pg 40]</ref> arguing that it would be "relatively easy" for a well funded entity with access to [[fusion boosting]] [[tritium]] and expertise to overcome the problem of pre-detonation created by the presence of Pu-240, and that a [[remote manipulation]] facility could be utilized in the assembly of the highly radioactive [[gamma ray]] emitting bomb components, coupled with a means of cooling the weapon [[Nuclear weapon design#Plutonium pit|pit]] during storage to prevent the plutonium charge contained in the pit from melting, and a design that kept the [[implosion-type nuclear weapon|implosion]] mechanisms [[high explosive]]s from being degraded by the pit's heat. However, with all these major design considerations included, this fusion boosted reactor grade plutonium primary will still fizzle if the fission component of the primary does not deliver more than 0.2 kilotons of yield, which is regarded as the minimum energy necessary to start a fusion burn.<ref>{{cite web |url=http://nuclearweaponarchive.org/Usa/Tests/Hardtack1.html |title= Operation Hardtack, test shot Juniper, 0.2 kt is approximately the yield of a boosted primary that fails to boost.}}</ref> The probability that a fission device would fail to achieve this threshold yield increases as the [[burnup]] value of the fuel increases.<ref name="J. Carson Mark"/> 
[[File:RUTH test tower 1953-03-31.jpg|thumb|200px|Tower of the [[Operation Upshot–Knothole|Upshot–Knothole Ruth]] test. During the early development of nuclear explosive devices, available fissile material that differed from the conventional [[special nuclear material]] forms, were tested. Pictured, is the results of a [[uranium hydride]] device. Post-shot limited structural damage from the [[fizzle (nuclear test)|fizzle]] explosion, estimated as equivalent to the [[Trinity (nuclear test)#Energy measurements|same nuclear energy emitted]] as 200 tons of the chemical energy in TNT(0.2 kilotons) failed to demolish the testing tower, only somewhat damaging it.]]
No information available in the public domain suggests that any well funded entity has ever seriously pursued creating a nuclear weapon with an isotopic composition similar to modern, high burnup, reactor grade plutonium. All [[nuclear weapon state]]s have taken the more conventional path to nuclear weapons by either [[uranium enrichment]] or producing low burnup, "fuel-grade" and weapons-grade plutonium, in reactors capable of operating as [[production reactor]]s, the isotopic content of reactor-grade plutonium, created by the most common commercial power reactor design, the [[pressurized water reactor]], never directly being considered for weapons use.<ref>[http://www.ccnr.org/plute.html States have been willing to make large investments in some cases to acquire weapon-grade rather than reactor-grade plutonium: the United States, for example, in the 1980s, considered spending billions of dollars on the Special Isotope Separation facility to enrich reactor-grade plutonium to weapon-grade.]</ref><ref>[https://www.osti.gov/biblio/106640-virtual-instruments-los-alamos-experiment Virtual instruments -- A Los Alamos experiment.Molecular laser isotope separation (MLIS) process in a gaseous plutonium hexafluoride ]</ref>

As of April 2012, there were [[Nuclear power by country|thirty-one countries]] that have civil nuclear power plants,<ref>{{cite web|url=http://www.world-nuclear.org/info/inf01.html |title=Nuclear Power in the World Today |publisher=World-nuclear.org |access-date=2013-06-22}}</ref> of which [[List of states with nuclear weapons|nine have nuclear weapons]], and almost every [[nuclear weapons state]] began producing weapons first instead of commercial nuclear power plants. The re-purposing of civilian nuclear industries for military purposes would be a breach of the [[Non-proliferation treaty]].

As nuclear reactor designs come in a wide variety and are sometimes improved over time, the isotopic ratio of what is deemed "reactor grade plutonium" in one design, as it compares to another, can differ substantially. For example, the British [[Magnox]] reactor, a Generation I [[gas cooled reactor]](GCR) design, can rarely produce a fuel [[burnup]] of more than 2-5&nbsp;[[kilowatt-hour|GWd]]/[[tonne|t]][[uranium|U]].<ref>{{cite web |url=https://www.forbes.com/sites/jeffmcmahon/2013/05/02/fancy-new-lids-for-nuclear-waste-casks-as-contents-get-hotter/ |title=Forbes magazine. Fancy New Lids for Nuclear Waste Casks, As Contents Get Hotter. "Status of Nuclear Power: A Global View IAEA 2005.|website=[[Forbes]]}}</ref><ref name="aesj.or.jp">{{cite web |url=http://www.aesj.or.jp/~recycle/gl2005pr1-4mr.sokolov.pdf |title=Status of Nuclear Power: A Global View Y. A. Sokolov Deputy Director General. IAEA}}</ref> Therefore, the "reactor grade plutonium" and the purity of Pu-239 from discharged magnox reactors is approximately 80%, depending on the burn up value.<ref name="page 19, table 1">[https://web.archive.org/web/20120214232829/http://www.nda.gov.uk/documents/upload/Plutonium-Options-for-Comment-August-2008.pdf page 19, table 1]</ref> In contrast, the generic civilian [[Pressurized water reactor]], routinely does (typical for 2015 [[Generation II reactor]]) 45&nbsp;[[GigaWatt|GW]]d/tU of [[burnup]], resulting in the purity of Pu-239 being 50.5%, alongside a Pu-240 content of 25.2%,<ref name="info.ornl.gov"/><ref name="fas.org"/> The remaining portion includes much more of the heat generating [[Pu-238]] and [[Pu-241]] isotopes than are to be found in the "reactor grade plutonium" from a Magnox reactor.

=="Reactor-grade" plutonium nuclear tests==
The '''reactor grade plutonium nuclear test''' was a "low-yield (under 20 kilotons)" [[Underground nuclear testing|underground]] [[nuclear test]] using non-[[weapons-grade]] [[plutonium]] conducted at the US [[Nevada Test Site]] in 1962.<ref name=DOE-199406>{{cite web |url=http://permanent.access.gpo.gov/websites/osti.gov/www.osti.gov/html/osti/opennet/document/press/pc29.html |title=Additional Information Concerning Underground Nuclear Weapon Test of Reactor-Grade Plutonium |publisher=[[US Department of Energy]] |date=June 1994 |access-date=2007-03-15}}</ref><ref>{{Cite web|last=Jones|first=Greg|date=6 May 2013|title=America's 1962 Reactor-Grade Plutonium Weapons Test Revisited|url=https://npolicy.org/greg-jones-americas-1962-reactor-grade-plutonium-weapons-test-revisited/|access-date=2021-12-22|language=en-US}}</ref> Some information regarding this test was declassified in July 1977, under instructions from President [[Jimmy Carter]], as background to his decision to prohibit [[nuclear reprocessing]] in the US.

The plutonium used for the 1962 test device was produced by the United Kingdom, and provided to the US under the [[1958 US-UK Mutual Defence Agreement]].<ref name=DOE-199406/>

The initial codename for the Magnox reactor design amongst the government agency which mandated it, the [[UKAEA]], was the ''Pressurised Pile Producing Power and Plutonium (PIPPA)'' and as this codename suggests, the reactor was designed as both a power plant and, when operated with low fuel "burn-up"; as a producer of plutonium-239 for the nascent nuclear weapons program in Britain.<ref>{{Cite web | url=http://www.world-nuclear.org/information-library/country-profiles/countries-t-z/appendices/nuclear-development-in-the-united-kingdom.aspx |title = Nuclear Development in the United Kingdom &#124;UK Nuclear Energy Development - World Nuclear Association}}</ref> This intentional dual-use approach to building electric power-reactors that could operate as production reactors in the early [[Cold War]] era, was typical of many nations' [[Generation II reactor|Generation I reactors]].<ref>{{cite book|doi=10.1533/9780857097552.1.69|chapter=Nuclear power plants: Types, components and material requirements |title=Structural Alloys for Power Plants |pages=69–101 |year=2014 |last1=Knott |first1=J. |isbn=9780857092380 }}</ref> With these being designs all focused on giving access to fuel after a short burn-up, which is known as [[Online refuelling]].

The [[2006 North Korean nuclear test]], the first by the DPRK, is also said to have had a Magnox reactor as the root source of its plutonium, operated in [[Yongbyon Nuclear Scientific Research Center]] in North Korea. This test detonation resulted in the creation of a low-yield fizzle explosion, producing an estimated yield of approximately 0.48 kilotons,<ref name=Lian>Lian-Feng Zhao, Xiao-Bi Xie, Wei-Min Wang, and Zhen-Xing Yao, "[http://www.bssaonline.org/content/98/6/2571.short Regional Seismic Characteristics of the 9 October 2006 North Korean Nuclear Test] {{Webarchive|url=https://web.archive.org/web/20150923195043/http://www.bssaonline.org/content/98/6/2571.short |date=23 September 2015 }}, ''Bulletin of the Seismological Society of America'', December 2008 98:2571-2589; doi:10.1785/0120080128</ref> from an undisclosed isotopic composition. The [[2009 North Korean nuclear test]] likewise was based on plutonium.<ref name=NYT-10061017>[https://www.nytimes.com/2006/10/17/world/asia/17diplo.html North Korean Fuel Identified as Plutonium] {{webarchive|url=https://web.archive.org/web/20161219221406/http://www.nytimes.com/2006/10/17/world/asia/17diplo.html |date=19 December 2016 }}, Thom Shanker and David E. Sanger, [[New York Times]], 17 October 2006</ref> Both produced a yield of 0.48 to 2.3 kiloton of TNT equivalent respectively and both were described as fizzle events due to their low yield, with some commentators even speculating whether, at the lower yield estimates for the 2006 test, the blast may have been the equivalent of US$100,000 worth of [[ammonium nitrate]].<ref name="WSJ1">{{cite news | url=https://www.wsj.com/articles/SB116070423640191496?mod=opinion | title=Commentary – Parody Physics Package? | author=Seitz, Russel | date=October 13, 2006 |work=Wall Street Journal | access-date=October 13, 2006| archive-url= https://web.archive.org/web/20090111053508/http://online.wsj.com/article/SB116070423640191496.html?mod=opinion| archive-date=January 11, 2009| url-status= live}}</ref><ref>Broad, William, "[https://www.nytimes.com/2013/02/13/world/asia/despite-claims-of-third-blast-north-korean-nuclear-program-remains-a-mystery.html?src=recg A Secretive Country Gives Experts Few Clues to Judge Its Nuclear Program]", ''New York Times'', 12 February 2013. "As is usual with tests by the secretive North, it was not even clear if the underground test was nuclear, rather than conventional bomb blasts meant to mimic an underground nuclear test;"</ref>

The isotopic composition of the 1962 US-UK test has similarly not been disclosed, other than the description ''reactor grade'', and it has not been disclosed which definition was used in describing the material for this test as ''reactor grade''.<ref name=DOE-199406 /> According to Alexander DeVolpi, the isotopic composition of the plutonium used in the US-UK 1962 test could not have been what we now consider to be reactor-grade, and the [[United States Department of Energy|DOE]] now implies, but doesn't assert, that the plutonium was fuel grade.<ref name="aps.org"/> Likewise, the [[World Nuclear Association]] suggests that the US-UK 1962 test had at least 85% [[plutonium-239]], a much higher isotopic concentration than what is typically present in the spent fuel from the majority of operating civilian reactors.<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>

In 2002 former Deputy Director General of the IAEA, Bruno Pelaud, stated that the DoE statement was misleading and that the test would have the modern definition of fuel-grade with a Pu-240 content of only 12%<ref>{{Cite book |last=Jones |first=Gregory S. |url=https://npolicy.org/books/Reactor-Grade_Plutonium_and_Nuclear_Weapons/Greg%20Jones_Reactor-grade%20plutonium%20web.pdf |title=Reactor-Grade Plutonium and Nuclear Weapons: Exploding the Myths |date=2018-02-20 |publisher=Nonproliferation Policy Education Center |isbn=978-0986289590 |language=en |chapter=Chapter 8. Did the U.S. and the British Test Reactor-Grade Plutonium in Nuclear Weapons?}}</ref>

In 1997 political analyst [[Matthew Bunn]] and presidential technology advisor [[John Holdren]], both of the [[Belfer Center for Science and International Affairs]], cited a 1990s official U.S. assessment of programmatic alternatives for plutonium disposition. While it does not specify which RGPu definition is being referred to, it nonetheless states that "reactor-grade plutonium (with an unspecified isotopic composition) can be used to produce nuclear weapons at all levels of technical sophistication," and "advanced nuclear weapon states such as the United States and Russia, using modern designs, could produce weapons from "reactor-grade plutonium" having reliable explosive yields, weight, and other characteristics generally comparable to those of weapons made from weapon-grade plutonium"<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] {{Webarchive|url=https://web.archive.org/web/20240119233430/https://www.belfercenter.org/sites/default/files/files/publication/mmup.pdf |date=2024-01-19 }}, Matthew Bunn and John P. Holdren, Annu. Rev. Energy Environ. 1997. 22:403–86</ref>

In a 2008 paper, Kessler et al. used a thermal analysis to conclude that a hypothetical nuclear explosive device was "technically unfeasible" using reactor grade plutonium from a reactor that had a burn up value of 30 GWd/t using "low technology" designs akin to [[Fat Man]] with spherical explosive lenses, or 55 GWd/t for "medium technology" designs.<ref>{{cite journal|doi=10.1016/j.nucengdes.2008.08.014|title=Potential nuclear explosive yield of reactor-grade plutonium using the disassembly theory of early reactor safety analysis|journal=Nuclear Engineering and Design|volume=238|issue=12|pages=3475–3499|year=2008|last1=Kessler|first1=G.|last2=Höbel|first2=W.|last3=Goel|first3=B.|last4=Seifritz|first4=W.|bibcode=2008NuEnD.238.3475K }}</ref>

According to the Kessler et al. criteria, "high-technology" hypothetical nuclear explosive devices (HNEDs), that could be produced by the experienced [[nuclear weapons state]]s (NWSs) would be technically unfeasible with reactor-grade plutonium containing more than approximately 9% of the heat generating [[Pu-238]] isotope.<ref>{{cite journal|doi=10.1016/j.nucengdes.2018.02.012|title=Proliferation resistant plutonium: An updated analysis|journal=Nuclear Engineering and Design|volume=330|pages=297–302|year=2018|last1=Lloyd|first1=Cody|last2=Goddard|first2=Braden|bibcode=2018NuEnD.330..297L }}</ref><ref>{{cite journal|url=https://www.jaea.go.jp/04/np/activity/2011-02-22/2011-02-22-08.pdf |title=A Consideration on Proliferation Resistance of a FBR Core Design. JAEA}}</ref>

==Typical isotopic composition of reactor grade plutonium==
The British Magnox reactor, a Generation I [[gas cooled reactor]] (GCR) design, can rarely produce a fuel [[burnup]] of more than 2-5&nbsp;[[kilowatt-hour|GWd]]/[[tonne|t]][[uranium|U]].<ref>{{cite web |url=https://www.forbes.com/sites/jeffmcmahon/2013/05/02/fancy-new-lids-for-nuclear-waste-casks-as-contents-get-hotter/ |title=Forbes magazine. Fancy New Lids for Nuclear Waste Casks, As Contents Get Hotter. "Status of Nuclear Power: A Global View IAEA 2005.|website=[[Forbes]]}}</ref><ref name="aesj.or.jp"/> The Magnox reactor design was codenamed ''PIPPA'' (Pressurised Pile Producing Power and Plutonium) by the [[UKAEA]] to denote the plant's dual commercial ([[nuclear power|power reactor]]) and military ([[production reactor]]) role. The purity of Pu-239 from discharged magnox reactors is approximately 80%, depending on the burn up value.<ref name="page 19, table 1"/>

In contrast, for example, a generic civilian [[Pressurized water reactor]]'s [[spent nuclear fuel]] isotopic composition, following a typical [[Generation II reactor]] 45&nbsp;[[GigaWatt|GW]]d/tU of [[burnup]], is 1.11% plutonium, of which 0.56% is Pu-239, and 0.28% is Pu-240, which corresponds to a Pu-239 content of 50.5% and a Pu-240 content of 25.2%.<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 34 figure 20. Discharge isotopic composition of a WE 17×17 assembly with initial enrichment of 4.5 wt % that has accumulated 45&nbsp;GWd/tU burnup/</ref> For a lower generic burn-up rate of 43,000 [[Megawatt|MWd]]/t, as published in 1989, the plutonium-239 content was 53% of all plutonium isotopes in the reactor [[spent nuclear fuel]].<ref name="fas.org"/> 
The US [[Nuclear Regulatory Commission|NRC]] has stated that the commercial fleet of [[LWR]]s presently powering homes, had an average [[burnup]] of approximately 35 GWd/MTU in 1995, while in 2015, the average had improved to 45 GWd/MTU.<ref>{{Cite web|url=https://www.nrc.gov/reading-rm/doc-collections/fact-sheets/bg-high-burnup-spent-fuel.html|archive-url = https://web.archive.org/web/20170226234425/https://www.nrc.gov/reading-rm/doc-collections/fact-sheets/bg-high-burnup-spent-fuel.html|archive-date = 2017-02-26|title = Backgrounder on High Burnup Spent Nuclear Fuel}}</ref>

The odd numbered fissile plutonium isotopes present in spent nuclear fuel, such as Pu-239, decrease significantly as a percentage of the total composition of all plutonium isotopes (which was 1.11% in the first example above) as higher and higher burnups take place, while the even numbered non-fissile plutonium isotopes (e.g. [[Pu-238]], [[Pu-240]] and [[Pu-242]]) increasingly accumulate in the fuel over time.<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 an assembly with initial U-235 enrichment of 4.5 wt % that has accumulated 45&nbsp;GWd/tU burnup. Isotopic composition of used nuclear fuel as a function of burnup for a generic PWR fuel assembly]</ref>

As power reactor technology develops, one goal is to reduce the spent nuclear fuel volume by increasing fuel efficiency and simultaneously reducing down times as much as possible to increase the economic viability of electricity generated from [[nuclear power plant|fission-electric stations]]. To this end, the reactors in the U.S. have doubled their average burn-up rates from 20 to 25 GWd/[[metric ton|MT]]U in the 1970s to over 45 GWd/[[metric ton|MT]]U in the 2000s.<ref name="aesj.or.jp"/><ref>{{cite web |url=https://www.forbes.com/sites/jeffmcmahon/2013/05/02/fancy-new-lids-for-nuclear-waste-casks-as-contents-get-hotter/ |title=Fancy New Lids for Nuclear Waste Casks, As Contents Get Hotter. "Status of Nuclear Power: A Global View IAEA 2005.|website=[[Forbes]]}}</ref> [[Generation III reactor]]s under construction have a designed-for [[burnup]] rate in the 60&nbsp;GWd/tU range and a need to refuel once every 2 years or so. For example,  the [[European Pressurized Reactor]] has a designed-for 65&nbsp;GWd/t,<ref name="world-nuclear">{{Cite web | url=http://world-nuclear.org/info/Nuclear-Fuel-Cycle/Power-Reactors/Advanced-Nuclear-Power-Reactors/ | title=Advanced Nuclear Power Reactors &#124; Generation III+ Nuclear Reactors - World Nuclear Association | access-date=2013-07-02 | archive-date=2014-08-27 | archive-url=https://web.archive.org/web/20140827084051/http://www.world-nuclear.org/info/Nuclear-Fuel-Cycle/Power-Reactors/Advanced-Nuclear-Power-Reactors/ | url-status=dead }}</ref> and the [[AP1000]] has a designed for average discharge burnup of 52.8&nbsp;GWd/t and a maximum of 59.5&nbsp;GWd/t.<ref name="world-nuclear" /> In-design [[generation IV reactor]]s will have [[burnup]] rates yet higher still.

==Reuse in reactors==
{{See also| Nuclear fuel cycle|minor actinides|La Hague site|Sellafield}}
[[File:Plutonium and uranium extraction from nuclear fuel-eng.svg|thumb|right|upright=1.6|Separation of uranium and plutonium from [[spent nuclear fuel]] by the 1940s-1950s wet-chemical [[PUREX]] method.<ref>Greenwood, pp. 1255, 1261</ref> This chemical process is controversial as it is likewise the path that produces chemically pure WGPu.]]
[[File:Ifr concept.jpg|thumb|375px|The 200+ GWd/TU of burnup fuel-cycle,<ref>{{cite journal
| author      = L. C. Walters
| date        =  September 18, 1998
| title       = Thirty years of fuels and materials information from EBR-II
| journal     = Journal of Nuclear Materials
| volume      = 270
| issue = 1–2
| pages       = 39–48
| publisher   = Elsevier
| doi=10.1016/S0022-3115(98)00760-0
|bibcode = 1999JNuM..270...39W | url = https://zenodo.org/record/1259635
}}</ref>
 proposed in the 1990s [[Integral fast reactor]](IFR) concept (color), an animation of the [[pyroprocessing]] technology is also available.<ref>{{cite web |url=https://www.youtube.com/watch?v=cBThTwFhRlA  |archive-url=https://ghostarchive.org/varchive/youtube/20211221/cBThTwFhRlA |archive-date=2021-12-21 |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>  As opposed to the standard practice worldwide of [[PUREX]] separation, plutonium is not separated on its own in this pilot-scale, reprocessing cycle, rather all [[actinides]] are "[[electrowinning|electro-won]]" or "refined" from the "true waste" of [[fission products]] in spent fuel. The plutonium therefore instead comes over mixed with all the [[MOX fuel#Americium content|gamma and alpha emitting actinides]], species that "self-protect" in numerous possible theft scenarios. For a reactor to operate on a full loading of this mixed actinide fuel, Fast neutron-spectrum reactors are without exception, the only variant considered possible.]]
[[File:IFR concept.png|thumb|IFR concept (Black and White with clearer text). The pyroprocessing cycle is not limited to sodium-fast-reactors such as the depicted IFR, many other conceptual reactors such as the Stable salt reactor are designed to rely on fuel from it, rather than PUREX.]]
Today's moderated/[[thermal reactor]]s primarily run on the [[Nuclear fuel cycle#Once-through nuclear fuel cycle|once-through fuel cycle]] though they can reuse once-through reactor-grade plutonium to a limited degree in the form of mixed-oxide or [[MOX fuel]], which is a routine commercial practice in most countries outside the US as it increases the sustainability of nuclear fission and lowers the volume of high level nuclear waste.<ref>{{cite journal|doi= 10.1016/j.energy.2014.02.069|title= Assessment of the environmental footprint of nuclear energy systems. Comparison between closed and open fuel cycles|journal= Energy|volume= 69|pages= 199–211|year= 2014|last1= Poinssot|first1= Ch.|last2= Bourg|first2= S.|last3= Ouvrier|first3= N.|last4= Combernoux|first4= N.|last5= Rostaing|first5= C.|last6= Vargas-Gonzalez|first6= M.|last7= Bruno|first7= J.|doi-access= free|bibcode= 2014Ene....69..199P}}</ref>

One third of the energy/fissions at the end of the practical fuel life in a thermal reactor are from plutonium, the end of cycle occurs when the [[U-235]] percentage drops, the primary fuel that drives the [[neutron economy]] inside the reactor and the drop necessitates fresh fuel being required, so without design change, one third of the fissile fuel in a new fuel load can be fissile reactor-grade plutonium with one third less of [[Low enriched uranium]] needing to be added to continue the chain reactions anew, thus achieving a partial recycling.<ref name="users.physics.harvard.edu">{{Cite web |url=http://users.physics.harvard.edu/~wilson/publications/ppaper643.html |title=''Plutonium Burning for Disposal of Pure Plutonium'', Richard Wilson Harvard University. |access-date=2018-05-15 |archive-date=2017-10-07 |archive-url=https://web.archive.org/web/20171007181015/http://users.physics.harvard.edu/~wilson/publications/ppaper643.html |url-status=dead }}</ref>

A typical 5.3% reactor-grade plutonium MOX fuel bundle, is [[Nuclear transmutation|transmutated]] when it itself is again burnt, a practice that is typical in French thermal reactors, to a twice-through reactor-grade plutonium, with an isotopic composition of 40.8% {{SimpleNuclide|pu|239}} and 30.6% {{SimpleNuclide|pu|240}} at the end of cycle (EOC).<ref name="oecd-nea.org">http://www.oecd-nea.org/pt/docs/1999/neastatus99/AnnexE.pdf See table B "MOX fuels".</ref><ref group="note" name="external">with the rest being 14.9% {{SimpleNuclide|pu|241}}, 10.6% {{SimpleNuclide|pu|242}} and 3.1% {{SimpleNuclide|pu|238}}</ref> MOX grade plutonium (MGPu) is generally defined as having more than 30% {{SimpleNuclide|pu|240}}.<ref name="web.archive.org"/>

A limitation in the number of recycles exists within [[thermal reactor]]s, as opposed to the situation in fast reactors, as in the [[thermal neutron]] spectrum only the odd-mass [[isotopes of plutonium]] are [[fissile]], the even-mass isotopes thus accumulate, in all high thermal-spectrum burnup scenarios. [[Plutonium-240]], an even-mass isotope is, within the thermal neutron spectrum, a [[fertile material]] like [[uranium-238]], becoming fissile [[plutonium-241]] on neutron capture; however, the even-mass [[plutonium-242]] not only has a low [[neutron capture]] [[Neutron cross-section|cross section]] within the thermal spectrum, it also requires 3 [[neutron capture]]s before becoming a fissile nuclide.<ref name="users.physics.harvard.edu"/>

While most thermal neutron reactors must limit MOX fuel to less than half of the total fuel load for nuclear stability reasons, due to the reactor design operating within the limitations of a thermal spectrum of neutrons, [[Fast neutron reactor]]s on the other hand can use plutonium of any isotopic composition, operate on completely recycled plutonium and in the fast "[[burner reactor|burner]]" mode, or fuel cycle, fission and thereby eliminate all the plutonium present in the world stockpile of once-through spent fuel.<ref>{{cite book|doi=10.1016/B978-1-78242-212-9.00009-5|chapter=Reprocessing of spent fast reactor nuclear fuels|title=Reprocessing and Recycling of Spent Nuclear Fuel|pages=213–243|year=2015|last1=Natarajan|first1=R.|isbn=9781782422129}}</ref>  The modernized IFR design, known as the [[S-PRISM]] concept and the [[Stable salt reactor]] concept, are two such fast reactors that are proposed to burn-up/eliminate the [[B205|plutonium stockpiles in Britain]] that was produced from operating its fleet of Magnox reactors generating the largest civilian stockpile of fuel-grade/"reactor-grade plutonium" in the world.<ref>
{{cite news
 | url= https://www.independent.co.uk/environment/green-living/new-life-for-old-idea-that-could-dissolve-our-nuclear-waste-2376882.html
 | title= New life for old idea that could dissolve our nuclear waste
 | date= 2011-10-28
 | work= The Independent
 | access-date= 2011-10-30
 | location=London
 | first=Steve
 | last=Connor}}
</ref>

In Bathke's equation on "attractiveness level" of [[Weapons-grade nuclear material]], the Figure of Merit(FOM) the calculation generates, returns the suggestion that Sodium Fast Breeder Reactors are unlikely to reach the desired level of proliferation resistance, while Molten Salt breeder reactors are more likely to do so.<ref>[https://web.archive.org/web/20171120061221/https://www.jaea.go.jp/04/np/activity/2011-02-22/2011-02-22-08.pdf A Consideration on Proliferation  Resistance of a FBR Core Design. JAEA]</ref>

In the [[fast breeder reactor]] cycle, or fast breeder mode, as opposed to the fast-burner, the French [[Phénix]] reactor uniquely demonstrated multi-recycling and reuses of its reactor grade plutonium.<ref>[https://www.iaea.org/NuclearPower/Downloadable/Meetings/2013/2013-03-04-03-07-CF-NPTD/T9.2/T9.2.guidez.pdf PHENIX A REPROCESSING AND MULTIPLE RECYCLING EXPERIMENT UNIQUE IN THE WORLD]</ref> Similar reactor concepts and fuel cycling, with the most well known being the [[Integral Fast Reactor]] are regarded as one of the few that can realistically achieve "planetary scale sustainability", powering a world of 10 billion, whilst still retaining a small environmental footprint.<ref>[http://www.mdpi.com/2071-1050/4/11/3088 Sustainable, Full-Scope Nuclear Fission Energy at Planetary Scale.  Sustainability 2012, 4(11), 3088-3123; https://doi.org/10.3390/su4113088]</ref> In breeder mode, fast reactors are therefore often proposed as a form of [[Nuclear power proposed as renewable energy#Conventional fission, breeder reactors as renewable|renewable or sustainable nuclear energy]]. Though the "[reactor-grade][[plutonium economy]]" it would generate, presently returns social distaste and varied arguments about proliferation-potential, in the public mindset.

As is typically found in civilian European thermal reactors, a 5.3% plutonium MOX fuel-bundle, produced by conventional wet-chemical/PUREX [[Nuclear reprocessing|reprocessing]] of an initial fuel assembly that generated 33 GWd/t before becoming [[spent nuclear fuel]], creates, when it itself is burnt in the thermal reactor, a [[spent nuclear fuel]] with a plutonium isotopic composition of 40.8% {{SimpleNuclide|pu|239}} and 30.6% {{SimpleNuclide|pu|240}}.<ref name="oecd-nea.org"/><ref group="note" name="external">with the rest being 14.9% {{SimpleNuclide|pu|241}}, 10.6% {{SimpleNuclide|pu|242}} and 3.1% {{SimpleNuclide|pu|238}}</ref>
[[File:RIAN archive 132603 Nuclear power reactor fuel assembly.jpg|thumb|A fresh [[nuclear fuel rod]] assembly bundle, being inspected before entering a reactor]]

Computations state that the energy yield of a nuclear explosive decreases by two [[orders of magnitude]] if the {{SimpleNuclide|pu|240}} content increases to 25%,(0.2 kt).<ref name=":1"/>

[[Nuclear reprocessing|Reprocessing]], which mainly takes the form of recycling reactor-grade plutonium back into the same or a more advanced fleet of reactors, was planned in the US in the 1960s. At that time the [[uranium market]] was anticipated to become crowded and supplies tight so together with recycling fuel, the more efficient [[fast breeder reactor]]s were thereby seen as immediately needed to efficiently use the limited known uranium supplies. This became less urgent as time passed, with both reduced demand forecasts and increased uranium ore discoveries, for these economic reasons, fresh fuel and the reliance on solely fresh fuel remained cheaper in commercial terms than recycled.

In 1977 the Carter administration placed a ban on reprocessing spent fuel, in an effort to set an international example, as within the US, there is the perception that it would lead to nuclear weapons proliferation.<ref>[https://www.forbes.com/sites/realspin/2014/10/01/why-doesnt-u-s-recycle-nuclear-fuel/#409b354a390f Why Doesn't U.S. Recycle Nuclear Fuel?]</ref> This decision has remained controversial and is viewed by many US physicists and engineers as fundamentally in error, having cost the US taxpayer and [[Nuclear Waste Policy Act#Payment of costs|the fund generated by US reactor utility operators]], with cancelled programs and the over 1 billion dollar investment into the proposed alternative, that of [[Yucca Mountain nuclear waste repository]] ending in protests, lawsuits and repeated stop-and-go decisions depending on the opinions of new incoming presidents.<ref>{{Cite web |url=http://users.physics.harvard.edu/~wilson/publications/ppaper643.html |title=''Plutonium Burning for Disposal of Pure Plutonium'', Richard Wilson Harvard University. "Using the European or Japanese reactors for burning plutonium, while the quickest means of accomplishing the task of burning weapons plutonium, would send a signal (undesired by this group of people) that the European and Japanese approach (which more closely resembles the Eisenhower approach than the Carter one) has merit. But the converse could also be true. A refusal to ask the rest of the world to help in burning plutonium can be, and in some quarters is taken as a signal that the United States is not serious about destroying weapons stocks. " |access-date=2018-05-15 |archive-date=2017-10-07 |archive-url=https://web.archive.org/web/20171007181015/http://users.physics.harvard.edu/~wilson/publications/ppaper643.html |url-status=dead }}</ref><ref>[http://www.phyast.pitt.edu/~blc/book/chapter13.html#1 Cohen. Chapter 13—THE NUCLEAR ENERGY OPTION  next=> PLUTONIUM AND BOMBS]</ref>
[[File:Nuclear dry storage.jpg|right|thumb|Following interim storage in a [[spent fuel pool]], the bundles of used fuel assemblies of a typical nuclear power station are often stored on site in the likes of the eight [[dry cask storage]] vessels pictured above.<ref>{{cite web|url=https://www.nrc.gov/waste/spent-fuel-storage/dry-cask-storage.html |title=NRC: Dry Cask Storage |publisher=Nrc.gov |date=2013-03-26 |access-date=2013-06-22}}</ref> At [[Yankee Rowe Nuclear Power Station]], which generated 44 billion [[kilowatt hours]] of electricity over its lifetime in the US, its complete spent fuel inventory is contained within sixteen casks.<ref>{{cite web|url=http://www.yankeerowe.com/ |title=Yankee Nuclear Power Plant |publisher=Yankeerowe.com |access-date=2013-06-22}}</ref> They are now awaiting a shipment decision towards a geological repository or to a domestic/foreign reprocessing facility.]]
As the "undesirable" contaminant from a weapons manufacturing viewpoint, {{SimpleNuclide|pu|240}}, decays faster than the {{SimpleNuclide|pu|239}}, with half lives of 6500 and 24,000 years respectively, the quality of the plutonium grade, increases with time (although its total quantity decreases during that time as well). Thus, physicists and engineers have pointed out, as hundreds/thousands of years pass, the alternative to fast reactor "burning"  or recycling of the plutonium from the world fleet of reactors until it is all burnt up, the alternative to burning most frequently proposed, that of deep [[geological repository]], such as [[Onkalo spent nuclear fuel repository]], have the potential to become "plutonium mines", from which weapons-grade material for nuclear weapons could be acquired by simple [[PUREX]] extraction, in the centuries-to-millennia to come.<ref>{{cite web |url=http://nci.org/s/sp121495.htm |title=A Perspective on the Proliferation Risks of Plutonium Mines |author=Lyman, Edwin S. |publisher=[[Nuclear Control Institute]] |date=December 1994 |access-date=2015-11-25 |url-status=live |archive-url=https://web.archive.org/web/20151125225922/http://nci.org/s/sp121495.htm |archive-date=2015-11-25 }}</ref><ref name="npolicy.org"/><ref>{{Cite journal |last=Lyman |first=Edwin S. |year=1998 |title=The Proliferation Risks of Plutonium Mines |url=https://scienceandglobalsecurity.org/archive/sgs07lyman.pdf |journal=Science & Global Security |volume=7 |pages=119-128}}</ref>

==Nuclear terrorism target==
{{see also|Nuclear terrorism}}
[[Aum Shinrikyo]], who succeeded in developing [[Sarin]] and [[VX (nerve agent)|VX nerve gas]] is regarded to have lacked the technical expertise to develop, or steal, a nuclear weapon. Similarly, [[Al Qaeda]] was exposed to numerous scams involving the sale of radiological waste and other non-weapons-grade material. The [[RAND corporation]] suggested that their repeated experience of failure and being scammed has possibly led to terrorists concluding that nuclear acquisition is too difficult and too costly to be worth pursuing.<ref>https://www.rand.org/pubs/research_briefs/RB165/index1.html Combating Nuclear Terrorism
Lessons from Aum Shinrikyo, Al Quaeda, and the Kinshasa [research] Reactor.</ref>

==See also==
{{portal|Nuclear technology}}
* [[Uranium hydride bomb]]s - produced a yield of about 0.2 kiloton

==References==
{{reflist|30em}}

==External links==
* [https://fas.org/rlg/980826-pu.htm Reactor-Grade Plutonium Can be Used to Make Powerful and Reliable Nuclear Weapons], [[Federation of American Scientists|FAS]], Richard Garwin, [[Council on Foreign Relations|CFR]], Congressional testimony, 1998
* [http://www.ccnr.org/plute.html Reactor-Grade and Weapons-Grade Plutonium in Nuclear Explosives], Canadian Coalition for Nuclear Responsibility
* [https://web.archive.org/web/20070316181800/http://www.rmi.org/images/other/Security/S80-01_NucWeaponsAndPluto.pdf Nuclear weapons and power-reactor plutonium], [[Amory B. Lovins]], February 28, 1980, [[Nature (journal)|Nature]], Vol. 283, No. 5750, pp.&nbsp;817–823
* {{cite book |chapter-url=https://books.google.com/books?id=cjhGcg_98kQC&pg=PA144 |title=Nuclear energy |chapter=The Nuclear Fuel Cycle: Does Reprocessing Make Sense? |editor=B. van der Zwaan |last=Garwin |first=Richard L. |page=144 |quote=But there is no doubt that the reactor-grade plutonium obtained from [[nuclear reprocessing|reprocessing]] [[LWR]] [[spent fuel]] can readily be used to make high-performance, high-reliability nuclear weaponry, as explained in the 1994 [[Committee on International Security and Arms Control]] (CISAC) publication. |publisher=World Scientific |isbn=978-981-02-4011-0 |date=1999-06-15}}
* [http://www.osti.gov/opennet/document/press/pc29.html Additional Information Concerning Underground Nuclear Weapon Test of Reactor-Grade Plutonium]
* [https://web.archive.org/web/20120520124004/http://depletedcranium.com/why-you-cant-build-a-bomb-from-spent-fuel/ Why You Can’t Build a Bomb From Spent Fuel]
* [https://fas.org/nuke/intro/nuke/O_9705.htm Plutonium Isotopics - Non-Proliferation And Safeguards Issues] {{Webarchive|url=https://web.archive.org/web/20150408232708/https://fas.org/nuke/intro/nuke/O_9705.htm |date=2015-04-08 }}
* [https://www.ieer.org/ensec/no-1/puuse.html  Plutonium as an Energy Source by Arjun Makhijani, Institute for Energy and Environmental Research]

{{reflist|group=note}}
{{Nuclear technology}}

[[Category:Nuclear weapons]]
[[Category:Nuclear materials]]
[[Category:Plutonium]]
[[Category:American nuclear weapons testing]]