Reactor-grade plutonium (RGPu)The categorisation of nuclear material in the context of integrated safeguards
/ref> is the isotopic grade of plutonium that is found in

spent nuclear fuel Spent nuclear fuel, occasionally called used nuclear fuel, is nuclear fuel that has been irradiated in a nuclear reactor (usually at a nuclear power plant). It is no longer useful in sustaining a nuclear reaction in an ordinary thermal reactor and ...

after the

uranium-235 Uranium-235 ( or U-235) is an isotope of uranium making up about 0.72% of natural uranium. Unlike the predominant isotope uranium-238, it is fissile, i.e., it can sustain a nuclear chain reaction. It is the only fissile isotope that exists in nat ...

primary fuel that a nuclear power reactor uses has burnt up. The

uranium-238 Uranium-238 ( or U-238) is the most common isotope of uranium found in nature, with a relative abundance of 99%. Unlike uranium-235, it is non-fissile, which means it cannot sustain a chain reaction in a thermal-neutron reactor. However, it i ...

from which most of the plutonium isotopes derive by

neutron capture Neutron capture is a nuclear reaction in which an atomic nucleus and one or more neutrons collide and merge to form a heavier nucleus. Since neutrons have no electric charge, they can enter a nucleus more easily than positively charged protons, wh ...

is found along with the U-235 in the

low enriched uranium Enriched uranium is a type of uranium in which the percent composition of uranium-235 (written 235U) has been increased through the process of isotope separation. Naturally occurring uranium is composed of three major isotopes: uranium-238 (238U ...

fuel of civilian reactors. In contrast to the low burnup of weeks or months that is commonly required to produce weapons-grade plutonium (WGPu/ ²³⁹Pu), the long time in the reactor that produces reactor-grade plutonium leads to transmutation of much of the

fissile In nuclear engineering, fissile material is material that can undergo nuclear fission when struck by a neutron of low energy. A self-sustaining thermal Nuclear chain reaction#Fission chain reaction, chain reaction can only be achieved with fissil ...

, relatively long

half-life Half-life is a mathematical and scientific description of exponential or gradual decay. Half-life, half life or halflife may also refer to: Film * Half-Life (film), ''Half-Life'' (film), a 2008 independent film by Jennifer Phang * ''Half Life: ...

isotope ²³⁹Pu into a number of other

isotopes of plutonium Plutonium (Pu) is an artificial element, except for trace quantities resulting from neutron capture by uranium, and thus a standard atomic weight cannot be given. Like all artificial elements, it has no stable isotopes. It was synthesized before ...

that are less fissile or more radioactive. When absorbs a neutron, it does not always undergo

nuclear fission Nuclear fission is a reaction in which the nucleus of an atom splits into two or more smaller nuclei. The fission process often produces gamma photons, and releases a very large amount of energy even by the energetic standards of radioactiv ...

. Sometimes neutron absorption will instead produce at the

neutron temperature The neutron detection temperature, also called the neutron energy, indicates a free neutron's kinetic energy, usually given in electron volts. The term ''temperature'' is used, since hot, thermal and cold neutrons are moderated in a medium with ...

s and fuel compositions present in typical

light water reactor The light-water reactor (LWR) is a type of thermal-neutron reactor that uses normal water, as opposed to heavy water, as both its coolant and neutron moderator; furthermore a solid form of fissile elements is used as fuel. Thermal-neutron react ...

s, with the concentration of steadily rising with longer irradiation, producing lower and lower grade plutonium as time goes on. Generation II

thermal-neutron reactor A thermal-neutron reactor is a nuclear reactor that uses slow or thermal neutrons. ("Thermal" does not mean hot in an absolute sense, but means in thermal equilibrium with the medium it is interacting with, the reactor's fuel, moderator and struct ...

s (today's most numerous

nuclear power station A nuclear power plant (NPP), also known as a nuclear power station (NPS), nuclear generating station (NGS) or atomic power station (APS) is a thermal power station in which the heat source is a nuclear reactor. As is typical of thermal power st ...

s) can reuse reactor-grade plutonium only to a limited degree as

MOX fuel Mixed oxide fuel (MOX fuel) is nuclear fuel that contains more than one oxide of fissile material, usually consisting of plutonium blended with natural uranium, reprocessed uranium, or depleted uranium. MOX fuel is an alternative to the low-enr ...

, and only for a second cycle.

Fast-neutron reactor A fast-neutron reactor (FNR) or fast-spectrum reactor or simply a fast reactor is a category of nuclear reactor in which the fission chain reaction is sustained by fast neutrons (carrying energies above 1 MeV, on average), as opposed to slow t ...

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

/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

At the beginning of the industrial scale production of plutonium-239 in war era '' production reactors'', trace contamination or co-production with

plutonium-240 Plutonium-240 ( or Pu-240) is an isotope of plutonium formed when plutonium-239 captures a neutron. The detection of its spontaneous fission led to its discovery in 1944 at Los Alamos and had important consequences for the Manhattan Project. ...

was initially observed, with these trace amounts resulting in the dropping of the Thin Man weapon-design as unworkable. The difference in purity, of how much, continues to be important in assessing significance in the context of

nuclear proliferation Nuclear proliferation is the spread of nuclear weapons to additional countries, particularly those not recognized as List of states with nuclear weapons, nuclear-weapon states by the Treaty on the Non-Proliferation of Nuclear Weapons, commonl ...

and weapons-usability. Sasahara

The DOE definition of ''reactor grade''

plutonium Plutonium is a chemical element; it has symbol Pu and atomic number 94. It is a silvery-gray actinide metal that tarnishes when exposed to air, and forms a dull coating when oxidized. The element normally exhibits six allotropes and four ...

changed in 1976. Before this, three grades were recognised. The change in the definition for ''reactor grade'', from describing plutonium with greater than 7% 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. * Super weapons grade, less than 3% 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% Pu-240 *Weapons grade, less than 7% Pu-240, *Fuel grade, 7% to 19% Pu-240 and *Reactor grade, more than 19% Pu-240. Reprocessing or recycling of the

spent fuel Spent nuclear fuel, occasionally called used nuclear fuel, is nuclear fuel that has been irradiated in a nuclear reactor (usually at a nuclear power plant). It is no longer useful in sustaining a nuclear reaction in an ordinary thermal reactor and ...

from the most common class of civilian-electricity-generating or ''power reactor'' design, the LWR, (with examples being the PWR or BWR) recovers ''reactor grade'' plutonium (as defined since 1976), not ''fuel grade''.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 GWd/tU burnup/https://fas.org/nuke/intro/nuke/plutonium.htm Source: Plutonium Fuel - OECD Report, 1989 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. 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 In nuclear power technology, burnup is a measure of how much energy is extracted from a given amount of nuclear fuel. It may be measured as the fraction of fuel atoms that underwent fission in %FIMA (fissions per initial heavy metal atom) or %FIF ...

. For this to be carried out in a

pressurized water reactor A pressurized water reactor (PWR) is a type of light-water nuclear reactor. PWRs constitute the large majority of the world's nuclear power plants (with notable exceptions being the UK, Japan, India and Canada). In a PWR, water is used both as ...

- the most common reactor design for electricity generation - the reactor would have to prematurely reach cold shut down after only recently being fueled, meaning that the reactor would need to cool

decay heat Decay heat is the heat released as a result of radioactive decay. This heat is produced as an effect of radiation on materials: the energy of the alpha particle, alpha, Beta particle, beta or gamma radiation is converted into the thermal movement ...

and then have its

reactor pressure vessel A reactor pressure vessel (RPV) in a nuclear power plant is the pressure vessel containing the nuclear reactor coolant, core shroud, and the reactor core. Classification of nuclear power reactors Russian Soviet era RBMK reactors have each fu ...

be depressurized, followed by a

fuel rod Nuclear fuel refers to any substance, typically fissile material, which is used by nuclear power stations or other nuclear devices to generate energy. Oxide fuel For fission reactors, the fuel (typically based on uranium) is usually based o ...

defueling. If such an operation were to be conducted, it would be easily detectable, and require prohibitively costly reactor modifications. One example of how this process could be detected in 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. On the other hand, the modern definition of "reactor grade" plutonium is produced only when the reactor is run at high

s and therefore producing a high electricity generating

capacity factor The net capacity factor is the unitless ratio of actual electrical energy output over a given period of time to the theoretical maximum electrical energy output over that period. The theoretical maximum energy output of a given installation is def ...

. According to the US Energy Information Administration (EIA), in 2009 the

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 A thermal power station, also known as a thermal power plant, is a type of power station in which the heat energy generated from various fuel sources (e.g., coal, natural gas, nuclear fuel, etc.) is converted to electrical energy. The heat ...

s at 63.8%, with down times being for simple routine maintenance and refuelling. The degree to which typical

Generation II reactor A generation II reactor is a design classification for a nuclear reactor, and refers to the class of commercial reactors built until the end of the 1990s. Prototypical and older versions of PWR, CANDU, BWR, AGR, RBMK and VVER are among them. ...

high burn-up produced reactor-grade plutonium is less useful than weapons-grade plutonium for building

nuclear weapon A nuclear weapon is an explosive device that derives its destructive force from nuclear reactions, either fission (fission or atomic bomb) or a combination of fission and fusion reactions (thermonuclear weapon), producing a nuclear exp ...

s is somewhat debated, with many sources arguing that the maximum probable theoretical yield would be bordering on a fizzle explosion of the range 0.1 to 2

kiloton TNT equivalent is a convention for expressing energy, typically used to describe the energy released in an explosion. A ton of TNT equivalent is a unit of energy defined by convention to be (). It is the approximate energy released in the det ...

in a

Fat Man "Fat Man" (also known as Mark III) was the design of the nuclear weapon the United States used for seven of the first eight nuclear weapons ever detonated in history. It is also the most powerful design to ever be used in warfare. A Fat Man ...

type device. As computations state that the energy yield of a nuclear explosive decreases by one and two

orders of magnitude In a ratio scale based on powers of ten, the order of magnitude is a measure of the nearness of two figures. Two numbers are "within an order of magnitude" of each other if their ratio is between 1/10 and 10. In other words, the two numbers are wi ...

if the 240 Pu content increases from 5% (nearly weapons-grade plutonium) to 15%( 2 kt) and 25%,(0.2 kt) respectively. 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 Spontaneous fission (SF) is a form of radioactive decay in which a heavy atomic nucleus splits into two or more lighter nuclei. In contrast to induced fission, there is no inciting particle to trigger the decay; it is a purely probabilistic proc ...

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 Improvised nuclear devices (INDs) are theoretical illicit nuclear weapons bought, stolen, or otherwise originating from a nuclear state, or a weapon fabricated by a terrorist group from illegally obtained fissile nuclear weapons material that pr ...

is described as presenting "daunting" hurdles for a

-era implosion design, and the possibility of terrorists achieving this fizzle yield being regarded as an "overblown" apprehension with the safeguards that are in place. 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 level yields can be achieved, arguing that it would be "relatively easy" for a well funded entity with access to

fusion boosting A boosted fission weapon usually refers to a type of nuclear bomb that uses a small amount of Nuclear fusion, fusion fuel to increase the rate, and thus yield, of a Nuclear fission, fission reaction. The Fusion neutron, fast fusion neutrons rele ...

tritium Tritium () or hydrogen-3 (symbol T or H) is a rare and radioactive isotope of hydrogen with a half-life of ~12.33 years. The tritium nucleus (t, sometimes called a ''triton'') contains one proton and two neutrons, whereas the nucleus of the ...

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 A gamma ray, also known as gamma radiation (symbol ), is a penetrating form of electromagnetic radiation arising from high energy interactions like the radioactive decay of atomic nuclei or astronomical events like solar flares. It consists o ...

emitting bomb components, coupled with a means of cooling the weapon pit during storage to prevent the plutonium charge contained in the pit from melting, and a design that kept the implosion mechanisms

high explosive An explosive (or explosive material) is a reactive substance that contains a great amount of potential energy that can produce an explosion if released suddenly, usually accompanied by the production of light, heat, sound, and pressure. An exp ...

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. The probability that a fission device would fail to achieve this threshold yield increases as the

value of the fuel increases. RUTH test tower 1953-03-31

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 states have taken the more conventional path to nuclear weapons by either

uranium enrichment Enriched uranium is a type of uranium in which the percent composition of uranium-235 (written 235U) has been increased through the process of isotope separation. Naturally occurring uranium is composed of three major isotopes: uranium-238 (23 ...

or producing low burnup, "fuel-grade" and weapons-grade plutonium, in reactors capable of operating as

production reactor A nuclear reactor is a device used to initiate and control a fission nuclear chain reaction. They are used for commercial electricity, marine propulsion, weapons production and research. Fissile nuclei (primarily uranium-235 or plutonium-2 ...

s, the isotopic content of reactor-grade plutonium, created by the most common commercial power reactor design, the

, never directly being considered for weapons use. As of April 2012, there were thirty-one countries that have civil nuclear power plants, of which nine have nuclear weapons, and almost every

nuclear weapons state Nine sovereign states are generally understood to possess nuclear weapons, though only eight formally acknowledge possessing them. United Nations Security Council#Permanent members, Five are considered to be nuclear-weapon states (NWS) unde ...

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 The Treaty on the Non-Proliferation of Nuclear Weapons, commonly known as the Non-Proliferation Treaty or NPT, is an international treaty whose objective is to prevent the spread of nuclear weapons and weapons technology, to promote cooperatio ...

. 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 Magnox is a type of nuclear power / production reactor that was designed to run on natural uranium with graphite as the moderator and carbon dioxide gas as the heat exchange coolant. It belongs to the wider class of gas-cooled reactors. The ...

reactor, a Generation I gas cooled reactor(GCR) design, can rarely produce a fuel

of more than 2-5 GWd/ t U. Therefore, the "reactor grade plutonium" and the purity of Pu-239 from discharged magnox reactors is approximately 80%, depending on the burn up value.page 19, table 1
/ref> In contrast, the generic civilian

Pressurized water reactor A pressurized water reactor (PWR) is a type of light-water nuclear reactor. PWRs constitute the large majority of the world's nuclear power plants (with notable exceptions being the UK, Japan, India and Canada). In a PWR, water is used both as ...

, routinely does (typical for 2015

) 45 GWd/tU of

, resulting in the purity of Pu-239 being 50.5%, alongside a Pu-240 content of 25.2%, 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 test Nuclear weapons tests are experiments carried out to determine the performance of nuclear weapons and the effects of their explosion. Nuclear testing is a sensitive political issue. Governments have often performed tests to signal strength. Bec ...

using non-

weapons-grade Weapons-grade nuclear material is any fissionable nuclear material that is pure enough to make a nuclear weapon and has properties that make it particularly suitable for nuclear weapons use. Plutonium and uranium in grades normally used in nuc ...

conducted at the US

Nevada Test Site The Nevada National Security Sites (N2S2 or NNSS), popularized as the Nevada Test Site (NTS) until 2010, is a reservation of the United States Department of Energy located in the southeastern portion of Nye County, Nevada, about northwest of ...

in 1962. Some information regarding this test was declassified in July 1977, under instructions from President

Jimmy Carter James Earl Carter Jr. (October 1, 1924December 29, 2024) was an American politician and humanitarian who served as the 39th president of the United States from 1977 to 1981. A member of the Democratic Party (United States), Democratic Party ...

, as background to his decision to prohibit

nuclear reprocessing Nuclear reprocessing is the chemical separation of fission products and actinides from spent nuclear fuel. Originally, reprocessing was used solely to extract plutonium for producing nuclear weapons. With commercialization of nuclear power, the ...

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. The initial codename for the Magnox reactor design amongst the government agency which mandated it, the

UKAEA The United Kingdom Atomic Energy Authority is a UK government research organisation responsible for the development of fusion energy. It is an executive non-departmental public body of the Department for Energy Security and Net Zero (DESNZ). T ...

, 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. This intentional dual-use approach to building electric power-reactors that could operate as production reactors in the early

Cold War The Cold War was a period of global Geopolitics, geopolitical rivalry between the United States (US) and the Soviet Union (USSR) and their respective allies, the capitalist Western Bloc and communist Eastern Bloc, which lasted from 1947 unt ...

era, was typical of many nations' Generation I reactors. 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 On October 9, 2006, North Korea performed its first nuclear test, detonating a plutonium-based device underground. On October 3, 2006, North Korea announced its intention to conduct a nuclear test. The blast is generally estimated to have had ...

, 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 The Nyongbyon Nuclear Scientific Research Center (녕변원자력연구소) is North Korea's major nuclear facility, operating its first nuclear reactors. It is located in Nyongbyon County in North Pyongan Province, about 100 km north of ...

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,Lian-Feng Zhao, Xiao-Bi Xie, Wei-Min Wang, and Zhen-Xing Yao,
Regional Seismic Characteristics of the 9 October 2006 North Korean Nuclear Test
, ''Bulletin of the Seismological Society of America'', December 2008 98:2571-2589; doi:10.1785/0120080128 from an undisclosed isotopic composition. The

2009 North Korean nuclear test The 2009 North Korean nuclear test was the underground detonation of a nuclear device conducted on Monday, 25 May 2009 by North Korea.North Korean Fuel Identified as Plutonium
, Thom Shanker and David E. Sanger,

New York Times ''The New York Times'' (''NYT'') is an American daily newspaper based in New York City. ''The New York Times'' covers domestic, national, and international news, and publishes opinion pieces, investigative reports, and reviews. As one of ...

, 17 October 2006 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 Ammonium nitrate is a chemical compound with the formula . It is a white crystalline salt consisting of ions of ammonium and nitrate. It is highly soluble in water and hygroscopic as a solid, but does not form hydrates. It is predominantly us ...

. 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''. 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 DOE now implies, but doesn't assert, that the plutonium was fuel grade. Likewise, the

World Nuclear Association World Nuclear Association is the international organization that promotes nuclear power and supports the companies that comprise the global nuclear industry. Its members come from all parts of the nuclear fuel cycle, including uranium mining ...

suggests that the US-UK 1962 test had at least 85%

plutonium-239 Plutonium-239 ( or Pu-239) is an isotope of plutonium. Plutonium-239 is the primary fissile isotope used for the production of nuclear weapons, although uranium-235 is also used for that purpose. Plutonium-239 is also one of the three main iso ...

, a much higher isotopic concentration than what is typically present in the spent fuel from the majority of operating civilian reactors. 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% In 1997 political analyst Matthew Bunn and presidential technology advisor John Holdren, both of the

Belfer Center for Science and International Affairs The Robert and Renée Belfer Center for Science and International Affairs, also known as the Belfer Center, is a research center located at the Harvard Kennedy School at Harvard University in Cambridge, Massachusetts, in the United States. From 2 ...

, 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" 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

with spherical explosive lenses, or 55 GWd/t for "medium technology" designs. According to the Kessler et al. criteria, "high-technology" hypothetical nuclear explosive devices (HNEDs), that could be produced by the experienced

s (NWSs) would be technically unfeasible with reactor-grade plutonium containing more than approximately 9% of the heat generating Pu-238 isotope.

Typical isotopic composition of reactor grade plutonium

The British Magnox reactor, a Generation I gas cooled reactor (GCR) design, can rarely produce a fuel

of more than 2-5 GWd/ t U. The Magnox reactor design was codenamed ''PIPPA'' (Pressurised Pile Producing Power and Plutonium) by the

to denote the plant's dual commercial ( power reactor) and military (

) role. The purity of Pu-239 from discharged magnox reactors is approximately 80%, depending on the burn up value. In contrast, for example, a generic civilian

isotopic composition, following a typical

45 GWd/tU of

, 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%. For a lower generic burn-up rate of 43,000 MWd/t, as published in 1989, the plutonium-239 content was 53% of all plutonium isotopes in the reactor

. The US NRC has stated that the commercial fleet of LWRs presently powering homes, had an average

of approximately 35 GWd/MTU in 1995, while in 2015, the average had improved to 45 GWd/MTU. 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. 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 fission-electric stations. To this end, the reactors in the U.S. have doubled their average burn-up rates from 20 to 25 GWd/ MTU in the 1970s to over 45 GWd/ MTU in the 2000s.

Generation III reactor Generation III reactors, or Gen III reactors, are a class of nuclear reactors designed to succeed Generation II reactors, incorporating evolutionary improvements in design. These include improved fuel technology, higher thermal efficiency, signi ...

s under construction have a designed-for

rate in the 60 GWd/tU range and a need to refuel once every 2 years or so. For example, the

European Pressurized Reactor The EPR is a Generation III+ pressurised water reactor design. It has been designed and developed mainly by Framatome (part of Areva between 2001 and 2017) and Électricité de France (EDF) in France, and by Siemens in Germany. In Europe, this ...

has a designed-for 65 GWd/t, and the

AP1000 The AP1000 is a nuclear power plant designed and sold by Westinghouse Electric Company. The plant is a pressurized water reactor with improved use of passive nuclear safety and many design features intended to lower its capital cost and improve ...

has a designed for average discharge burnup of 52.8 GWd/t and a maximum of 59.5 GWd/t. In-design

generation IV reactor Generation IV (Gen IV) reactors are nuclear reactor design technologies that are envisioned as successors of generation III reactors. The Generation IV International Forum (GIF) – an international organization that coordinates the development of ...

s will have

rates yet higher still.

Reuse in reactors

Plutonium and uranium extraction from nuclear fuel-eng

Today's moderated/

thermal reactor A thermal-neutron reactor is a nuclear reactor that uses slow or thermal neutrons. ("Thermal" does not mean hot in an absolute sense, but means in thermal equilibrium with the medium it is interacting with, the reactor's fuel, moderator and stru ...

s primarily run on the once-through fuel cycle though they can reuse once-through reactor-grade plutonium to a limited degree in the form of mixed-oxide or

, 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. 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 Uranium-235 ( or U-235) is an isotope of uranium making up about 0.72% of natural uranium. Unlike the predominant isotope uranium-238, it is fissile, i.e., it can sustain a nuclear chain reaction. It is the only fissile isotope that exists in nat ...

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 Enriched uranium is a type of uranium in which the percent composition of uranium-235 (written 235U) has been increased through the process of isotope separation. Naturally occurring uranium is composed of three major isotopes: uranium-238 (238U ...

needing to be added to continue the chain reactions anew, thus achieving a partial recycling. A typical 5.3% reactor-grade plutonium MOX fuel bundle, is 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% and 30.6% at the end of cycle (EOC).http://www.oecd-nea.org/pt/docs/1999/neastatus99/AnnexE.pdf See table B "MOX fuels".with the rest being 14.9% , 10.6% and 3.1% MOX grade plutonium (MGPu) is generally defined as having more than 30% . A limitation in the number of recycles exists within

s, as opposed to the situation in fast reactors, as in the

thermal neutron The neutron detection temperature, also called the neutron energy, indicates a free neutron's kinetic energy, usually given in electron volts. The term ''temperature'' is used, since hot, thermal and cold neutrons are moderated in a medium wit ...

spectrum only the odd-mass

are

, the even-mass isotopes thus accumulate, in all high thermal-spectrum burnup scenarios.

Plutonium-240 Plutonium-240 ( or Pu-240) is an isotope of plutonium formed when plutonium-239 captures a neutron. The detection of its spontaneous fission led to its discovery in 1944 at Los Alamos and had important consequences for the Manhattan Project. ...

, an even-mass isotope is, within the thermal neutron spectrum, a

fertile material Fertile material is a material that, although not fissile itself, can be converted into a fissile material by neutron absorption. Naturally occurring fertile materials Naturally occurring fertile materials that can be converted into a fissile ...

, becoming fissile

plutonium-241 Plutonium-241 ( or Pu-241) is an isotope of plutonium formed when plutonium-240 captures a neutron. Like some other plutonium isotopes (especially 239Pu), 241Pu is fissile, with a neutron absorption cross section about one-third greater than t ...

on neutron capture; however, the even-mass plutonium-242 not only has a low

cross section Cross section may refer to: * Cross section (geometry) ** Cross-sectional views in architecture and engineering 3D *Cross section (geology) * Cross section (electronics) * Radar cross section, measure of detectability * Cross section (physics) **A ...

within the thermal spectrum, it also requires 3

s before becoming a fissile nuclide. 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 A fast-neutron reactor (FNR) or fast-spectrum reactor or simply a fast reactor is a category of nuclear reactor in which the fission nuclear chain reaction, chain reaction is sustained by fast neutrons (carrying energies above 1 Electronvolt, MeV, ...

s on the other hand can use plutonium of any isotopic composition, operate on completely recycled plutonium and in the fast " burner" mode, or fuel cycle, fission and thereby eliminate all the plutonium present in the world stockpile of once-through spent fuel. The modernized IFR design, known as the S-PRISM concept and the

Stable salt reactor The stable salt reactor (SSR) is a nuclear reactor design under development by Moltex Energy Canada Inc. and its subsidiary Moltex Energy USA LLC, based in Canada, the United States, and the United Kingdom, as well as MoltexFLEX, Ltd., MoltexFLEX ...

concept, are two such fast reactors that are proposed to burn-up/eliminate the 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. In Bathke's equation on "attractiveness level" of

Weapons-grade nuclear material Weapons-grade nuclear material is any fissionable nuclear material that is pure enough to make a nuclear weapon and has properties that make it particularly suitable for nuclear weapons use. Plutonium and uranium in grades normally used in nuc ...

, 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. In the

fast breeder reactor A breeder reactor is a nuclear reactor that generates more fissile material than it consumes. These reactors can be Nuclear fuel, fueled with more-commonly available isotopes of uranium and Isotopes of thorium, thorium, such as uranium-238 and t ...

cycle, or fast breeder mode, as opposed to the fast-burner, the French

Phénix Phénix (French for phoenix) was a small-scale (gross 264/net 233 MWe) prototype fast breeder reactor, located at the Marcoule nuclear site, near Orange, France. It was a pool-type liquid-metal fast breeder reactor cooled with liquid sodium. ...

reactor uniquely demonstrated multi-recycling and reuses of its reactor grade plutonium. Similar reactor concepts and fuel cycling, with the most well known being the

Integral Fast Reactor The integral fast reactor (IFR), originally the advanced liquid-metal reactor (ALMR), is a design for a nuclear reactor using fast neutrons and no neutron moderator (a "fast" reactor). IFRs can breed more fuel and are distinguished by a nuclea ...

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. In breeder mode, fast reactors are therefore often proposed as a form of renewable or sustainable nuclear energy. Though the " eactor-grade lutonium 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 reprocessing of an initial fuel assembly that generated 33 GWd/t before becoming

, creates, when it itself is burnt in the thermal reactor, a

with a plutonium isotopic composition of 40.8% and 30.6% .with the rest being 14.9% , 10.6% and 3.1% RIAN archive 132603 Nuclear power reactor fuel assembly

Computations state that the energy yield of a nuclear explosive decreases by two

if the content increases to 25%,(0.2 kt). 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 The uranium market, like all commodity markets, has a history of volatility, moving with the standard forces of supply and demand as well as geopolitical pressures. It has also evolved particularities of its own in response to the unique nature ...

was anticipated to become crowded and supplies tight so together with recycling fuel, the more efficient

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. This decision has remained controversial and is viewed by many US physicists and engineers as fundamentally in error, having cost the US taxpayer and 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 The Yucca Mountain Nuclear Waste Repository, as designated by the Nuclear Waste Policy Act amendments of 1987, is a proposed deep geological repository storage facility within Yucca Mountain for spent nuclear fuel and other high-level radioact ...

ending in protests, lawsuits and repeated stop-and-go decisions depending on the opinions of new incoming presidents. Nuclear dry storage

As the "undesirable" contaminant from a weapons manufacturing viewpoint, , decays faster than the , 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 The Onkalo spent nuclear fuel repository is a deep geological repository for the final disposal of spent nuclear fuel. It is near the Olkiluoto Nuclear Power Plant in the municipality of Eurajoki, on the west coast of Finland. It will be the wo ...

, have the potential to become "plutonium mines", from which weapons-grade material for nuclear weapons could be acquired by simple

PUREX PUREX (plutonium uranium reduction extraction) is a chemical method used to purify fuel for nuclear reactors or nuclear weapons. It is based on liquid–liquid extraction ion-exchange. PUREX is the '' de facto'' standard aqueous nuclear reproc ...

extraction, in the centuries-to-millennia to come.

Nuclear terrorism target

Aum Shinrikyo , better known by their former name , is a Japanese new religions, Japanese new religious movement and doomsday cult founded by Shoko Asahara in 1987. It carried out the deadly Tokyo subway sarin attack in 1995 and was found to have been respo ...

, who succeeded in developing

Sarin Sarin (NATO designation GB nerve_agent#G-series.html" ;"title="hort for nerve agent#G-series">G-series, "B" is an extremely toxic organophosphorus compound.VX nerve gas is regarded to have lacked the technical expertise to develop, or steal, a nuclear weapon. Similarly,

Al Qaeda , image = Flag of Jihad.svg , caption = Jihadist flag, Flag used by various al-Qaeda factions , founder = Osama bin Laden{{Assassinated, Killing of Osama bin Laden , leaders = {{Plainlist, * Osama bin Lad ...

was exposed to numerous scams involving the sale of radiological waste and other non-weapons-grade material. The

RAND corporation The RAND Corporation, doing business as RAND, is an American nonprofit global policy think tank, research institute, and public sector consulting firm. RAND engages in research and development (R&D) in several fields and industries. Since the ...

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.https://www.rand.org/pubs/research_briefs/RB165/index1.html Combating Nuclear Terrorism Lessons from Aum Shinrikyo, Al Quaeda, and the Kinshasa esearchReactor.

References

External links

Reactor-Grade Plutonium Can be Used to Make Powerful and Reliable Nuclear Weapons
FAS, Richard Garwin, CFR, Congressional testimony, 1998
Reactor-Grade and Weapons-Grade Plutonium in Nuclear Explosives
Canadian Coalition for Nuclear Responsibility
Nuclear weapons and power-reactor plutonium
Amory B. Lovins, February 28, 1980,

Nature Nature is an inherent character or constitution, particularly of the Ecosphere (planetary), ecosphere or the universe as a whole. In this general sense nature refers to the Scientific law, laws, elements and phenomenon, phenomena of the physic ...

, Vol. 283, No. 5750, pp. 817–823 *
Additional Information Concerning Underground Nuclear Weapon Test of Reactor-Grade Plutonium

Why You Can’t Build a Bomb From Spent Fuel

{{Nuclear technology Nuclear weapons Nuclear materials Plutonium American nuclear weapons testing