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{{About|the radioactive element}}
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{{infobox plutonium}}
'''Plutonium''' is a [[transuranium element|transuranic]] [[radioactive decay|radioactive]] [[chemical element]] with the [[chemical symbol|symbol]]&nbsp;'''Pu''' and [[atomic number]]&nbsp;94. It is an [[actinide]] [[metal]] of silvery-gray appearance that [[tarnish]]es when exposed to air, and forms a dull coating when [[plutonium(IV) oxide|oxidized]]. The element normally exhibits six [[allotrope]]s and four [[oxidation state]]s. It reacts with [[carbon]], [[halogen]]s, [[nitrogen]], [[silicon]] and [[hydrogen]]. When exposed to moist air, it forms [[oxide]]s and [[hydride]]s that expand the sample up to 70% in volume, which in turn flake off as a powder that can [[pyrophoricity|spontaneously ignite]]. It is [[radiation poisoning|radioactive]] and can accumulate in the [[bone]]s. These properties make the handling of plutonium dangerous.
 
Plutonium is the heaviest [[primordial element]] by virtue of its most stable [[isotopes of plutonium|isotope]], [[plutonium-244]], whose [[half-life]] of about 80&nbsp;million years is just long enough for the element to be found in trace quantities in nature.<ref>{{cite journal|doi = 10.1038/234132a0|url=http://www.nature.com/nature/journal/v234/n5325/abs/234132a0.html|title= Detection of Plutonium-244 in Nature|journal = Nature|pages = 132–134|year = 1971|last1 = Hoffman|first1 = D. C.|last2 = Lawrence|first2 = F. O.|last3 = Mewherter|first3 = J. L.|last4 = Rourke|first4 = F. M.|volume = 234|bibcode = 1971Natur.234..132H|issue=5325}}</ref> Plutonium is mostly a byproduct of [[nuclear reactions]] in reactors where some of the [[neutron]]s released by the [[nuclear fission|fission]] process convert uranium-238 nuclei into plutonium.<ref>[http://www.nytimes.com/2011/03/29/world/asia/29japan.html "Contaminated Water Escaping Nuclear Plant, Japanese Regulator Warns"]. ''[[The New York Times]]''.</ref>
 
Both [[plutonium-239]] and [[plutonium-241]] are [[fissile]], meaning that they can sustain a [[nuclear chain reaction]], leading to applications in [[nuclear weapon]]s and [[nuclear reactor]]s. [[Plutonium-240]] exhibits a high rate of [[spontaneous fission]], raising the [[neutron flux]] of any sample containing it. The presence of plutonium-240 limits a plutonium sample's usability for weapons or its quality as reactor fuel, and the percentage of plutonium-240 determines its [[reactor-grade plutonium|grade]] (weapons grade, fuel grade, or reactor grade).
 
[[Plutonium-238]] has a half-life of 88&nbsp;years and emits [[alpha particle]]s. It is a heat source in [[radioisotope thermoelectric generator]]s, which are used to power some [[spacecraft]]. Plutonium isotopes are expensive and inconvenient to separate, so particular isotopes are usually manufactured in specialized reactors.
 
A team led by [[Glenn T. Seaborg]] and [[Edwin McMillan]] at the [[University of California, Berkeley]], first synthesized plutonium in 1940  by bombarding [[uranium-238]] with [[deuteron]]s. Trace amounts of plutonium were subsequently discovered in nature. Producing plutonium in useful quantities for the first time was a major part of the [[Manhattan Project]] during [[World War II]], which developed the first atomic bombs. The first [[nuclear test]], "[[Trinity (nuclear test)|Trinity]]" (July 1945), and the second atomic bomb used to destroy a city ([[Atomic bombings of Hiroshima and Nagasaki|Nagasaki, Japan, in August 1945]]), "[[Fat Man]]", both had cores of plutonium-239. [[Human radiation experiments]] studying plutonium were conducted without [[informed consent]], and several [[criticality accident]]s, some lethal, occurred during and after the war. Disposal of [[nuclear waste|plutonium waste]] from [[nuclear power plant]]s and [[nuclear disarmament|dismantled nuclear weapons]] built during the [[Cold War]] is a [[nuclear proliferation|nuclear-proliferation]] and environmental concern. Other sources of [[plutonium in the environment]] are [[nuclear fallout|fallout]] from numerous above-ground nuclear tests (now [[Partial Test Ban Treaty|banned]]).
 
==Characteristics==
 
===Physical properties===
<!-- [[File:Radii of the actinides.svg|left|thumb|Radii of actinides]] -->
Plutonium, like most metals, has a bright silvery appearance at first, much like [[nickel]], but it [[plutonium(IV) oxide|oxidizes]] very quickly to a dull gray, although yellow and olive green are also reported.<ref name = "WISER">
{{cite web
|url = http://webwiser.nlm.nih.gov/getSubstanceData.do;jsessionid=89B673C34252C77B4C276F2B2D0E4260?substanceID=419&displaySubstanceName=Plutonium,%20Radioactive&UNNAID=&STCCID=&selectedDataMenuItemID=44
|author = NIH contributors
|publisher = U.S. National Library of Medicine, National Institutes of Health
|location = Bethesda (MD)
|title = Plutonium, Radioactive
|work = Wireless Information System for Emergency Responders (WISER)
|accessdate = November 23, 2008
}} (public domain text)</ref><ref>
{{cite journal
|title = Nitric acid processing
|url = http://arq.lanl.gov/source/orgs/nmt/nmtdo/AQarchive/3rdQuarter08/page3.shtml
|journal = Actinide Research Quarterly
|author = ARQ staff
|year = 2008
|issue = 3rd quarter
|publisher = Los Alamos National Laboratory
|location = Los Alamos (NM)
|quote = While plutonium dioxide is normally olive green, samples can be various colors. It is generally believed that the color is a function of chemical purity, stoichiometry, particle size, and method of preparation, although the color resulting from a given preparation method is not always reproducible.
|accessdate =February 9, 2010
}}</ref> At room temperature plutonium is in its [[allotropes of plutonium|α form]] (''alpha''). This, the most common structural form of the element ([[allotrope]]), is about as hard and brittle as [[cast iron#Grey cast iron|grey cast iron]] unless it is [[alloy]]ed with other metals to make it soft and ductile. Unlike most metals, it is not a good conductor of [[thermal conductivity|heat]] or [[electrical conductivity|electricity]]. It has a low [[melting point]] (640&nbsp;°C) and an unusually high [[boiling point]] (3,228&nbsp;°C).<ref name = "WISER"/>
 
[[Alpha decay]], the release of a high-energy [[helium]] nucleus, is the most common form of [[radioactive decay]] for plutonium.<ref name = "NNDC"/> A 5&nbsp;kg mass of <sup>239</sup>Pu contains about {{val|12.5|e=24}} atoms. With a half-life of 24,100 years, about {{val|11.5|e=12}} of its atoms decay each second by emitting a 5.157&nbsp;[[MeV]] alpha particle. This amounts to 9.68 watts of power. Heat produced by the deceleration of these alpha particles makes it warm to the touch.<ref name = "Heiserman1992">{{harvnb|Heiserman|1992|p=338}}</ref><ref>
{{cite book
|last = Rhodes |first = Richard
|year = 1986
|title = The Making of the Atomic Bomb
|isbn = 0-671-65719-4
|pages = 659–660
|publisher = Simon & Schuster
|location = New York}} Leona Marshall: "When you hold a lump of it in your hand, it feels warm, like a live rabbit"</ref>
 
[[Resistivity]] is a measure of how strongly a material opposes the flow of [[electric current]]. The resistivity of plutonium at room temperature is very high for a metal, and it gets even higher with lower temperatures, which is unusual for metals.<ref name = "Miner1968p544"/> This trend continues down to 100&nbsp;[[Kelvin|K]], below which resistivity rapidly decreases for fresh samples.<ref name = "Miner1968p544"/> Resistivity then begins to increase with time at around 20&nbsp;K due to radiation damage, with the rate dictated by the isotopic composition of the sample.<ref name = "Miner1968p544"/>
 
Because of self-irradiation, a sample of plutonium fatigues throughout its crystal structure, meaning the ordered arrangement of its atoms becomes disrupted by radiation with time.<ref name = "HeckerPlutonium" /> Self-irradiation can also lead to [[annealing (metallurgy)|annealing]] which counteracts some of the fatigue effects as temperature increases above 100&nbsp;K.<ref>
{{cite journal
|title = Aging of Plutonium and Its Alloys
|page = 242
|journal = Los Alamos Science
|year = 2000
|issue = 26
|url = http://library.lanl.gov/cgi-bin/getfile?00818029.pdf
|format = PDF
|last = Hecker
|first = Siegfried S.
|coauthors = Martz, Joseph C.
|location = Los Alamos, New Mexico
|publisher = Los Alamos National Laboratory
|accessdate = February 15, 2009
}}</ref>
 
Unlike most materials, plutonium ''increases'' in density when it melts, by 2.5%, but the liquid metal exhibits a linear decrease in density with temperature.<ref name="Miner1968p544">{{harvnb|Miner|1968|p = 544}}</ref> Near the melting point, the liquid plutonium has also very high [[viscosity]] and [[surface tension]] as compared to other metals.<ref name = "HeckerPlutonium"/>
 
===Allotropes===
{{Main|Allotropes of plutonium}}
[[File:Plutonium density-eng.svg|thumb|280px|Plutonium has six allotropes at ambient pressure: '''alpha'''&nbsp;(α), '''beta'''&nbsp;(β), '''gamma'''&nbsp;(γ), '''delta'''&nbsp;(δ), '''delta&nbsp;prime'''&nbsp;(δ'), & '''epsilon'''&nbsp;(ε)<ref name = "Baker1983"/>|alt=A graph showing change in density with increasing temperature upon sequential phase transitions between alpha, beta, gamma, delta, delta' and epsilon phases]]
<!--[[File:Pu-phases.png|thumb]]-->
Plutonium normally has six allotropes and forms a seventh (zeta, ζ) at high temperature within a limited pressure range.<ref name = "Baker1983">
{{cite journal
|url = http://library.lanl.gov/cgi-bin/getfile?07-16.pdf
|title = Plutonium: A Wartime Nightmare but a Metallurgist's Dream
|last = Baker
|first = Richard D.
|coauthors = Hecker, Siegfried S.; Harbur, Delbert R.
|journal = Los Alamos Science
|year = 1983
|publisher = Los Alamos National Laboratory
|pages = 148, 150–151
|accessdate = February 15, 2009
}}</ref><!-- Note: page 148 --> These allotropes, which are different structural modifications or forms of an element, have very similar [[internal energy|internal energies]] but significantly varying [[density|densities]] and [[crystal structure]]s. This makes plutonium very sensitive to changes in temperature, pressure, or chemistry, and allows for dramatic volume changes following [[phase transition]]s from one allotropic form to another.<ref name = "HeckerPlutonium">
{{cite journal
|first = Siegfried S.
|last = Hecker
|title = Plutonium and its alloys: from atoms to microstructure
|journal = Los Alamos Science
|volume = 26
|year = 2000
|pages = 290–335
|url = http://www.fas.org/sgp/othergov/doe/lanl/pubs/00818035.pdf
|format = PDF
|accessdate = February 15, 2009
}}</ref> The densities of the different allotropes vary from 16.00&nbsp;g/cm<sup>3</sup> to 19.86&nbsp;g/cm<sup>3</sup>.<ref name="CRC2006p4-27" />
 
The presence of these many allotropes makes machining plutonium very difficult, as it changes state very readily. For example, the α form exists at room temperature in unalloyed plutonium. It has machining characteristics similar to [[cast iron]] but changes to the plastic and malleable β form (''beta'') at slightly higher temperatures.<ref name = "Miner1968p542"/> The reasons for the complicated phase diagram are not entirely understood. The α form has a low-symmetry [[monoclinic crystal system|monoclinic]] structure, hence its brittleness, strength, compressibility, and poor thermal conductivity.<ref name = "Baker1983"/>
 
Plutonium in the δ form normally exists in the 310&nbsp;°C to 452&nbsp;°C range but is stable at room temperature when alloyed with a small percentage of [[gallium]], [[aluminium]], or [[cerium]], enhancing workability and allowing it to be [[welding|welded]].<ref name = "Miner1968p542"/> The delta form has more typical metallic character, and is roughly as strong and malleable as aluminium.<ref name = "Baker1983"/> In fission weapons, the explosive [[shock wave]]s used to compress a plutonium core will also cause a transition from the usual delta phase plutonium to the denser alpha form, significantly helping to achieve [[supercriticality]].<ref>{{cite news|url=http://www.globalsecurity.org/wmd/intro/pu-phase.htm|title=Plutonium Crystal Phase Transitions|publisher=GlobalSecurity.org}}</ref> The ε phase, the highest temperature solid allotrope, exhibits anomalously high atomic [[self-diffusion]] compared to other elements.<ref name = "HeckerPlutonium"/>
 
===Nuclear fission===
[[File:Plutonium ring.jpg|right|150px|thumb|A ring of [[weapons-grade]] 99.96% pure electrorefined plutonium, enough for one [[nuclear weapon design#Plutonium pit|bomb core]]. The ring weighs 5.3&nbsp;kg, is ca. 11&nbsp;cm in diameter and its shape helps with [[nuclear criticality safety|criticality safety]].|alt=A rusty metal cylinder]]
 
Plutonium is a radioactive [[actinide]] metal whose [[isotope]], [[plutonium-239]], is one of the three primary [[fissile]] isotopes<ref name = "Stwertka1998">{{harvnb|Stwertka|1998}}</ref> ([[uranium-233]] and [[uranium-235]] are the other two);<ref>
{{cite web
|url = http://www.epa.gov/rpdweb00/glossary/termdef.html#f
|title = Fissile Material
|work = Radiation Glossary
|publisher = United States Environmental Protection Agency
|year = 2008
|accessdate = November 23, 2008
|author = EPA contributors
}}</ref>
[[plutonium-241]] is also highly fissile.
To be considered fissile, an isotope's [[atomic nucleus]] must be able to break apart or [[nuclear fission|fission]] when struck by a [[neutron temperature|slow moving neutron]] and to release enough additional neutrons to sustain the [[nuclear chain reaction]] by splitting further nuclei.
 
Pure plutonium-239 may have a [[four factor formula|multiplication factor]] (k<sub>eff</sub>) larger than one, which means that if the metal is present in sufficient quantity and with an appropriate geometry (e.g., a sphere of sufficient size), it can form a [[critical mass]].<ref>
{{cite book
|title = Understanding Physics
|last = Asimov
|first = Isaac
|authorlink = Isaac Asimov
|page = 905
|chapter = Nuclear Reactors
|year = 1988
|isbn = 0-88029-251-2
|publisher = Barnes & Noble Publishing}}</ref> During fission, a fraction of the [[binding energy]], which holds a nucleus together, is released as a large amount of electromagnetic and kinetic energy (much of the latter being quickly converted to thermal energy). Fission of a kilogram of plutonium-239 can produce an explosion equivalent to {{convert|21,000|tonTNT|lk=on}}.<ref name = "Heiserman1992"/> It is this energy that makes plutonium-239 useful in [[nuclear weapon]]s and [[nuclear reactor|reactors]].
 
The presence of the isotope [[plutonium-240]] in a sample limits its nuclear bomb potential, as plutonium-240 has a relatively high [[spontaneous fission]] rate (~440 fissions per second per gram—over 1,000 neutrons per second per gram),<ref>Samuel Glasstone and Leslie M. Redman, ''[http://www.doeal.gov/opa/docs/RR00171.pdf An Introduction to Nuclear Weapons]'' (Atomic Energy Commission Division of Military Applications Report WASH-1038, June 1972), p. 12.</ref> raising the background neutron levels and thus increasing the risk of [[fizzle (nuclear test)|predetonation]].<ref>
{{cite book
|title = The Manhattan Project: Making the Atomic Bomb
|publisher = United States Department of Energy
|id = DOE/MA-0001-01/99
|location = Oak Ridge (TN)
|last = Gosling
|first = F.G.
|page = 40
|url = http://www.cfo.doe.gov/me70/manhattan/publications/DE99001330.pdf
|year = 1999
|accessdate = February 15, 2009
|isbn = 0-7881-7880-6
}}</ref> Plutonium is identified as either [[weapons-grade]], fuel grade, or power reactor grade based on the percentage of plutonium-240 that it contains. Weapons-grade plutonium contains less than 7% plutonium-240. [[reactor-grade plutonium|Fuel grade plutonium]] contains from 7% to less than 19%, and power reactor grade contains 19% or more plutonium-240. [[plutonium-239#Supergrade plutonium|Supergrade plutonium]], with less than 4% of plutonium-240, is used in [[United States Navy|U.S. Navy]] weapons stored in proximity to ship and submarine crews, due to its lower radioactivity.<ref>
{{cite book
|title = Plutonium: The First 50 Years
|publisher = U.S. Department of Energy
|year = 1996
|id = DOE/DP-1037
|author = DOE contributors
|url = http://www.doeal.gov/SWEIS/DOEDocuments/004%20DOE-DP-0137%20Plutonium%2050%20Years.pdf
}} (public domain text)</ref> The isotope [[plutonium-238]] is not [[fissile#Fissile vs fissionable|fissile but can undergo nuclear fission]] easily with [[fast neutrons]] as well as [[alpha decay]].<ref name = "Heiserman1992"/>
 
===Isotopes and synthesis===
[[File:PuIsotopes.png|thumb|340px|Uranium-plutonium and thorium-uranium chains|alt=A diagram illustrating the interconversions between various isotopes of uranium, thorium, protactinium and plutonium]]
<!-- [[File:Plutonium and uranium extraction from nuclear fuel-rus.svg|right]] -->
{{Main|Isotopes of plutonium}}
Twenty [[radioisotope|radioactive isotopes]] of plutonium have been characterized. The longest-lived are plutonium-244, with a half-life of 80.8&nbsp;million years, plutonium-242, with a half-life of 373,300&nbsp;years, and plutonium-239, with a half-life of 24,110&nbsp;years. All of the remaining radioactive isotopes have half-lives that are less than 7,000&nbsp;years. This element also has eight [[meta state|metastable states]], though all have half-lives less than one second.<ref name = "NNDC">
{{cite web
|url = http://www.nndc.bnl.gov/chart/
|author = NNDC contributors
|coauthors = Alejandro A. Sonzogni (Database Manager)
|title = Chart of Nuclides
|publisher = National Nuclear Data Center, [[Brookhaven National Laboratory]]
|accessdate = September 13, 2008
|year = 2008
|location = Upton (NY)
}}</ref>
 
The isotopes of plutonium range in [[mass number]] from 228 to 247. The primary [[radioactive decay|decay modes]] of isotopes with mass numbers lower than the most stable isotope, plutonium-244, are [[spontaneous fission]] and [[alpha emission|α emission]], mostly forming uranium (92 [[proton]]s) and [[neptunium]] (93 protons) isotopes as [[decay product]]s (neglecting the wide range of daughter nuclei created by fission processes). The primary decay mode for isotopes with mass numbers higher than plutonium-244 is [[beta emission|β emission]], mostly forming [[americium]] (95 protons) isotopes as decay products. Plutonium-241 is the [[parent isotope]] of the [[neptunium decay series]], decaying to americium-241 via β or electron emission.<ref name = "NNDC"/><ref name=p340>{{harvnb|Heiserman|1992|p=340}}</ref>
 
Plutonium-238 and 239 are the most widely synthesized isotopes.<ref name = "Heiserman1992"/> Plutonium-239 is synthesized via the following reaction using uranium (U) and neutrons (n) via beta decay (β<sup>−</sup>) with neptunium (Np) as an intermediate:<ref>{{cite journal|first=J. W.|last=Kennedy|coauthors=Seaborg, G. T.; Segrè, E.; Wahl, A. C.|title=Properties of Element 94|journal=Physical Review|year=1946|issue=7–8|pages=555–556|doi=10.1103/PhysRev.70.555|volume=70|bibcode = 1946PhRv...70..555K}}</ref>
 
:<math>\mathrm{^{238}_{\ 92}U\ +\ ^{1}_{0}n\ \longrightarrow \ ^{239}_{\ 92}U\ \xrightarrow[23.5 \ min]{\beta^-} \ ^{239}_{\ 93}Np\ \xrightarrow[2.3565 \ d]{\beta^-} \ ^{239}_{\ 94}Pu}</math>
 
Neutrons from the fission of uranium-235 are [[neutron capture|captured]] by uranium-238 nuclei to form uranium-239; a [[beta decay]] converts a neutron into a proton to form Np-239 (half-life 2.36&nbsp;days) and another beta decay forms plutonium-239.<ref name = "Greenwood1997p1259">{{harvnb|Greenwood|1997|p = 1259}}</ref> Workers on the [[Tube Alloys]] project had predicted this reaction theoretically in 1940.
 
Plutonium-238 is synthesized by bombarding uranium-238 with [[deuteron]]s (D, the nuclei of heavy [[hydrogen]]) in the following reaction:<ref>{{cite journal|first=Glenn T.|last=Seaborg|coauthors=McMillan, E.; Kennedy, J. W.; Wahl, A. C.|title=Radioactive Element 94 from Deuterons on Uranium|journal=Physical Review|year=1946|issue=7–8|pages=366–367|doi=10.1103/PhysRev.69.367|volume=69|bibcode = 1946PhRv...69..367S}}</ref>
 
:<math>\mathrm{^{238}_{\ 92}U\ +\ ^{2}_{1}D\ \longrightarrow \ ^{238}_{\ 93}Np\ +\ 2\ ^{1}_{0}n \quad;\quad ^{238}_{\ 93}Np\ \xrightarrow[2.117 \ d]{\beta^-} \ ^{238}_{\ 94}Pu}</math>
 
In this process, a deuteron hitting uranium-238 produces two neutrons and neptunium-238, which spontaneously decays by emitting negative beta particles to form plutonium-238.
 
===Decay heat and fission properties===
Plutonium isotopes undergo radioactive decay, which produces [[decay heat]]. Different isotopes produce different amounts of heat per mass. The decay heat is usually listed as watt/kilogram, or milliwatt/gram. In case of larger pieces of plutonium (e.g. a weapon pit) and inadequate heat removal the resulting self-heating may be significant. All isotopes produce weak gamma on decay.
 
{| class="wikitable"
|+ Decay heat of plutonium isotopes<ref>{{cite web|url=http://www.cnfc.or.jp/e/proposal/reports/index.html|title=Can Reactor Grade Plutonium Produce Nuclear Fission Weapons?|date=May 2001|publisher=Council for Nuclear Fuel Cycle Institute for Energy Economics, Japan}}</ref>
! Isotope !! [[Decay mode]] !! [[Half-life]] (years) !! [[Decay heat]] (W/kg) !! [[Spontaneous fission]] neutrons (1/(g·s)) !! Comment
|-
! [[plutonium-238|<sup>238</sup>Pu]]
| alpha to [[uranium-234|<sup>234</sup>U]]
| 87.74
| 560
| 2600
| Very high decay heat. Even in small amounts can cause significant self-heating. Used on its own in [[radioisotope thermoelectric generator]]s.
|-
! [[plutonium-239|<sup>239</sup>Pu]]
| alpha to [[uranium-235|<sup>235</sup>U]]
| 24100
| 1.9
| 0.022
| The principal fissile isotope in use.
|-
! [[plutonium-240|<sup>240</sup>Pu]]
| alpha to [[uranium-236|<sup>236</sup>U]], spontaneous fission
| 6560
| 6.8
| 910
| The principal impurity in samples of the <sup>239</sup>Pu isotope. The plutonium grade is usually listed as percentage of <sup>240</sup>Pu. High spontaneous fission hinders use in nuclear weapons.
|-
! [[plutonium-241|<sup>241</sup>Pu]]
| beta-minus, to [[Americium-241|<sup>241</sup>Am]]
| 14.4
| 4.2
| 0.049
| Decays to americium-241; its buildup presents a radiation hazard in older samples.
|-
! [[plutonium-242|<sup>242</sup>Pu]]
| alpha to [[uranium-238|<sup>238</sup>U]]
| 376000
| 0.1
| 1700
|
|}
 
[[Americium-241]], the decay product of plutonium-241, has half-life of 430 years, 1.2 spontaneous fissions per gram per second, and decay heat of 114 watts per kilogram. As its decay produces highly penetrative gamma rays, its presence in plutonium, determined by the original concentration of plutonium-241 and the sample age, increases the radiation exposure of surrounding structures and personnel.
 
===Compounds and chemistry===
<!-- http://ru.wikipedia.org/wiki/Файл:Бинарные_соединения_плутония.svg -->
{{Category see also|Plutonium compounds}}
[[File:Plutonium in solution.jpg|thumb|right|300px|Various oxidation states of plutonium in solution|alt=Five liuids in glass bottles: violet, label Pu(III); dark brown, label Pu(IV)HClO4; light purple, label Pu(V); light brown, label Pu(VI); dark green, label Pu(VII).]]
At room temperature, pure plutonium is silvery in color but gains a tarnish when oxidized.<ref>{{harvnb|Heiserman|1992|p=339}}</ref> The element displays four common ionic [[oxidation state]]s in [[aqueous solution]] and one rare one:<ref name = "CRC2006p4-27"/>
* Pu(III), as Pu<sup>3+</sup> (blue lavender)
* Pu(IV), as Pu<sup>4+</sup> (yellow brown)
* Pu(V), as {{chem|PuO|2|+}} (light pink)<ref group = note>The {{chem|PuO|2|+}} ion is unstable in solution and will disproportionate into Pu<sup>4+</sup> and {{chem|PuO|2|2+}}; the Pu<sup>4+</sup> will then oxidize the remaining {{chem|PuO|2|+}} to {{chem|PuO|2|2+}}, being reduced in turn to Pu<sup>3+</sup>. Thus, aqueous solutions of {{chem|PuO|2|+}} tend over time towards a mixture of Pu<sup>3+</sup> and {{chem|PuO|2|2+}}. [[Uranium#Aqueous chemistry|{{chem|UO|2|+}}]] is unstable for the same reason.
:{{cite web
|title = Nuclear Criticality Safety Engineering Training Module 10 – Criticality Safety in Material Processing Operations, Part 1
|url = http://ncsp.llnl.gov/ncset/Module10.pdf
|format = PDF
|accessdate = February 15, 2006
|year = 2002
|last = Crooks
|first = William J.
}}</ref>
* Pu(VI), as {{chem|PuO|2|2+}} (pink orange)
* Pu(VII), as {{chem|PuO|5|3-}} (green)–the heptavalent ion is rare
 
The color shown by plutonium solutions depends on both the oxidation state and the nature of the acid [[anion]].<ref>
{{cite book
|last = Matlack
|first = George
|title = A Plutonium Primer: An Introduction to Plutonium Chemistry and its Radioactivity
|publisher = Los Alamos National Laboratory
|year = 2002
|id = LA-UR-02-6594
}}</ref> It is the acid anion that influences the degree of [[complex (chemistry)|complexing]]—how atoms connect to a central atom—of the plutonium species.
 
Metallic plutonium is produced by reacting [[plutonium tetrafluoride]] with [[barium]], [[calcium]] or [[lithium]] at 1200&nbsp;°C.<ref>
{{cite book
|title = Concise Encyclopedia Chemistry
|last = Eagleson
|first = Mary
|publisher = Walter de Gruyter
|isbn = 978-3-11-011451-5
|page = 840
|year = 1994
}}</ref> It is attacked by [[acid]]s, [[oxygen]], and steam but not by [[alkalis]] and dissolves easily in concentrated [[hydrochloric acid|hydrochloric]], [[hydroiodic acid|hydroiodic]] and [[perchloric acid]]s.<ref name = "Miner1968p545">{{harvnb|Miner|1968|p = 545}}</ref> Molten metal must be kept in a [[vacuum]] or an [[inert atmosphere]] to avoid reaction with air.<ref name = "Miner1968p542">{{harvnb|Miner|1968|p = 542}}</ref> At 135&nbsp;°C the metal will ignite in air and will explode if placed in [[carbon tetrachloride]].<ref name = "Emsley2001"/>
 
[[File:Plutonium pyrophoricity.jpg|thumb|left|upright|Plutonium [[pyrophoricity]] can cause it to look like a glowing ember under certain conditions.|alt=A black block on a table with red spots on top and yellow powder around it.]]
[[File:96602765.lowres.jpeg|thumb|upright|alt=Cross-section of a glass vial showing brownish-white snow-like precipitation on the bottom.|Twenty micrograms of pure plutonium hydroxide.<ref>[http://imglib.lbl.gov/ImgLib/COLLECTIONS/BERKELEY-LAB/RESEARCH-1930-1990/NUCLEAR-PHYSICS/TRANSURANIUM-ELEMENTS/index/96602765.html Pure plutonium hydroxide in capillary tube], LBNL Image Library</ref>]]
Plutonium is a reactive metal. In moist air or moist [[argon]], the metal oxidizes rapidly, producing a mixture of [[oxide]]s and [[hydride]]s.<ref name = "WISER"/> If the metal is exposed long enough to a limited amount of water vapor, a powdery surface coating of [[plutonium(IV) oxide|PuO<sub>2</sub>]] is formed.<ref name = "WISER"/> Also formed is [[plutonium hydride]] but an excess of water vapor forms only PuO<sub>2</sub>.<ref name = "Miner1968p545"/>
 
With this coating, the metal is [[pyrophoricity|pyrophoric]], meaning it can ignite spontaneously, so plutonium metal is usually handled in an inert, dry atmosphere of nitrogen or argon. Oxygen retards the effects of moisture and acts as a [[passivation (chemistry)|passivating]] agent.<ref name = "WISER"/>
 
Plutonium shows enormous, and reversible, reaction rates with pure hydrogen, forming [[plutonium hydride]].<ref name = "HeckerPlutonium"/> It also reacts readily with oxygen, forming PuO and PuO<sub>2</sub> as well as intermediate oxides; plutonium oxide fills 40% more volume than plutonium metal. The metal reacts with the [[halogen]]s, giving rise to [[chemical compound|compounds]] with the general formula PuX<sub>3</sub> where X can be [[plutonium(III) fluoride|F]], [[plutonium(III) chloride|Cl]], Br or I and [[plutonium tetrafluoride|PuF<sub>4</sub>]] is also seen. The following oxyhalides are observed: PuOCl, PuOBr and PuOI. It will react with carbon to form PuC, nitrogen to form PuN and [[silicon]] to form PuSi<sub>2</sub>.<ref name = "CRC2006p4-27"/><ref name = "Emsley2001"/>
 
[[Crucible]]s used to contain plutonium need to be able to withstand its strongly [[redox|reducing]] properties. [[Refractory metals]] such as [[tantalum]] and [[tungsten]] along with the more stable oxides, [[boride]]s, [[carbide]]s, [[nitride]]s and [[silicide]]s can tolerate this. Melting in an [[electric arc furnace]] can be used to produce small ingots of the metal without the need for a crucible.<ref name = "Miner1968p542"/>
 
[[Cerium]] is used as a chemical simulant of plutonium for development of containment, extraction, and other technologies.<ref>{{cite journal|title=Low Temperature Reaction of ReillexTM HPQ and Nitric Acid|author=Crooks, W. J. ''et al.''|url=http://sti.srs.gov/fulltext/ms2000068/ms2000068.html|doi=10.1081/SEI-120014371|journal=Solvent Extraction and Ion Exchange|volume=20|year=2002|page=543|issue=4–5}}</ref>
 
====Electronic structure====
Plutonium is an element in which the [[f shell|5f electrons]] are the transition border between delocalized and localized; it is therefore considered one of the most complex elements.<ref name="physicsworld.com">{{cite news|url=http://physicsworld.com/cws/article/news/16443|title=Plutonium is also a superconductor|publisher=PhysicsWeb.org|author=Dumé, Belle|date=November 20, 2002}}</ref> The anomalous behavior of plutonium is caused by its electronic structure. The energy difference between the 6d and 5f subshells is very low. The size of the 5f shell is just enough to allow the electrons to form bonds within the lattice, on the very boundary between localized and bonding behavior. The proximity of energy levels leads to multiple low-energy electron configurations with near equal energy levels. This leads to competing 5f<sup>n</sup>7s<sup>2</sup> and 5f<sup>n-1</sup>7s<sup>2</sup>6d<sup>1</sup> configurations, which causes the complexity of its chemical behavior. The highly directional nature of 5f orbitals is responsible for directional covalent bonds in molecules and complexes of plutonium.<ref name = "HeckerPlutonium"/>
 
===Alloys===
Plutonium can form [[alloy]]s and intermediate compounds with most other metals. Exceptions include [[lithium]], [[sodium]], [[potassium]], [[rubidium]] and [[caesium]] of the [[alkali metal]]s; and [[magnesium]], [[calcium]], [[strontium]], and [[barium]] of the [[alkaline earth metal]]s; and [[europium]] and [[ytterbium]] of the [[rare earth metal]]s.<ref name = "Miner1968p545"/> Partial exceptions include the refractory metals [[chromium]], [[molybdenum]], [[niobium]], [[tantalum]], and [[tungsten]], which are soluble in liquid plutonium, but insoluble or only slightly soluble in solid plutonium.<ref name = "Miner1968p545"/> [[Gallium]], [[aluminium]], [[americium]], [[scandium]] and [[cerium]] can stabilize the δ phase of plutonium for room temperature. [[Silicon]], [[indium]], [[zinc]] and [[zirconium]] allow formation of metastable δ state when rapidly cooled. High amounts of [[hafnium]], [[holmium]] and [[thallium]] also allows retaining some of the δ phase at room temperature. [[Neptunium]] is the only element that can stabilize the α phase at higher temperatures.<ref name = "HeckerPlutonium"/>
 
Plutonium alloys can be produced by adding a metal to molten plutonium. If the alloying metal is sufficiently reductive, plutonium can be added in the form of oxides or halides. The δ phase plutonium-gallium and plutonium-aluminium alloys are produced by adding [[plutonium(III) fluoride]] to molten gallium or aluminium, which has the advantage of avoiding dealing directly with the highly reactive plutonium metal.<ref>{{cite book|url=http://books.google.com/?id=W3FnEOg8tS4C&pg=PA169|page=169|title=Nuclear forensic analysis|author=Moody, Kenton James; Hutcheon, Ian D.; Grant, Patrick M.|publisher=CRC Press|year=2005|isbn=0-8493-1513-1}}</ref>
* [[Plutonium-gallium alloy|Plutonium-gallium]] is used for stabilizing the δ phase of plutonium, avoiding the α-phase and α-δ related issues. Its main use is in [[pit (nuclear weapon)|pits]] of [[nuclear weapons design|implosion nuclear weapons]].<ref>{{cite journal|url=http://books.google.com/?id=0o4DnYptWdgC&pg=PA71|page=71|title=ECS transactions|publisher=Electrochemical Society |author=Kolman, D. G. and Colletti, L. P.|chapter=The aqueous corrosion behavior of plutonium metal and plutonium-gallium alloys exposed to aqueous nitrate and chloride solutions|volume=16|year=2009|issue=52|isbn=978-1-56677-751-3}}</ref>
* '''Plutonium-aluminium''' is an alternative to the Pu-Ga alloy. It was the original element considered for δ phase stabilization, but its tendency to react with the alpha particles and release neutrons reduces its usability for nuclear weapon pits. Plutonium-aluminium alloy can be also used as a component of [[nuclear fuel]].<ref>{{cite book|url=http://www.csirc.net/docs/reports/ref_066.pdf|title=Canadian Research Reactors|author=Hurst, D. G. and Ward, A. G.|publisher= Los Alamos National Laboratory}}</ref>
* '''Plutonium-gallium-cobalt''' alloy (PuCoGa<sub>5</sub>) is an [[unconventional superconductor]], showing superconductivity below 18.5 [[kelvin]], an order of magnitude higher than the highest between [[heavy fermion]] systems, and has large critical current.<ref name="physicsworld.com"/><ref>{{cite journal|url=http://www.lanl.gov/orgs/mpa/files/mrhighlights/LALP-06-072.pdf|author=Curro, N. J. |title=Unconventional superconductivity in PuCoGa5|date=Spring 2006|publisher=Los Alamos National Laboratory}}</ref>
* '''Plutonium-zirconium''' alloy can be used as [[nuclear fuel]].<ref>McCuaig, Franklin D. "Pu-Zr alloy for high-temperature foil-type fuel" {{US patent|4059439}}, Issued on November 22, 1977</ref>
* '''Plutonium-cerium''' and '''plutonium-cerium-cobalt''' alloys are used as nuclear fuels.<ref>{{cite book|url=http://books.google.com/?id=L79odes2ihEC&pg=PA73|page=73|title=Nuclear Energy|author=Jha, D.K.|publisher=Discovery Publishing House|year=2004|isbn=81-7141-884-8}}</ref>
* '''Plutonium-uranium''', with about 15–30&nbsp;mol.% plutonium, can be used as a nuclear fuel for fast breeder reactors. Its [[pyrophoric]] nature and high susceptibility to corrosion to the point of self-igniting or disintegrating after exposure to air require alloying with other components. Addition of aluminium, carbon or copper did not improve disintegration rates markedly, zirconium and iron alloys have better corrosion resistance but they disintegrate in several months in air as well. Addition of titanium and/or zirconium significantly increases the melting point of the alloy.<ref name="Pu1965">{{cite book|url=http://books.google.com/?id=8r8NAAAAQAAJ&pg=PA456|page=456|title=plutonium 1965|publisher=Taylor & Francis|year=1965}}</ref>
* '''Plutonium-uranium-titanium''' and '''plutonium-uranium-zirconium''' were investigated for use as nuclear fuels. The addition of the third element increases corrosion resistance, reduces flammability, and improves ductility, fabricability, strength, and thermal expansion. '''Plutonium-uranium-molybdenum''' has the best corrosion resistance, forming a protective film of oxides, but titanium and zirconium are preferred for physics reasons.<ref name="Pu1965" />
* '''Thorium-uranium-plutonium''' was investigated as a nuclear fuel for fast breeder reactors.<ref name="Pu1965" />
 
===Occurrence===
<!-- NEEDS CLEANUP & CITES
As of 2002, 1,200 tonnes of plutonium<ref>Overview of Plutonium and Its Health Effects by Casey Burns April, 2002</ref> has been produced in [[nuclear reactor]]s, and from [[nuclear reprocessing]] sources that are well documented http://www.epa.gov/radiation/radionuclides/plutonium.html#wheredoes. This plutonium occurs in local areas? where it is stored under security due to its hazardous nature. During the manufacture and testing of nuclear weapons a certain amount of plutonium has been released into the wider environment, an estimate of 12.7 tonnes from the U.S weapons program alone.<ref>"Quality Status Report 2000 for the North East-Atlantic (Regional QSR III, Chapter 4 Chemistry, p66" (http:/ / www. ospar. org/ eng/ doc/ pdfs/ R3C4. pdf) (PDF). OSPAR Commission. Retrieved 3 June 2007.] Plutonium Wastes from the U.S. Nuclear Weapons Complex</ref> In addition during plutonium's manufacture in civil nuclear reactors some plutonium has by accident and design escaped into the biosphere and has been found in sediment layers and aquatic species [[Sellafield]].
-->
Trace amounts of at least three plutonium isotopes (plutonium-238, 239, and 244) can be found in nature. Small traces of plutonium-239, a few [[parts per notation|parts per trillion]], and its [[decay product]]s are naturally found in some concentrated ores of uranium,<ref name = "Miner1968p541"/> such as the [[natural nuclear fission reactor]] in [[Oklo]], [[Gabon]].<ref>
{{cite web
|url = http://www.ocrwm.doe.gov/factsheets/doeymp0010.shtml
|title = Oklo: Natural Nuclear Reactors
|publisher = U.S. Department of Energy, Office of Civilian Radioactive Waste Management
|year = 2004
|author = DOE contributors
|accessdate = November 16, 2008
|archiveurl = http://web.archive.org/web/20081020201724/http://www.ocrwm.doe.gov/factsheets/doeymp0010.shtml <!--Added by H3llBot-->
|archivedate = October 20, 2008
}}</ref> The ratio of plutonium-239 to uranium at the [[Cigar Lake Mine]] uranium deposit ranges from {{val|2.4|e=-12}} to {{val|44|e=-12}}.<ref name = "Cigar">
{{cite journal
|journal = Geochimica et Cosmochimica Acta
|volume = 63|issue = 2|pages = 275–285
|year = 1999
|doi = 10.1016/S0016-7037(98)00282-8
|title = Nature's uncommon elements: plutonium and technetium
|first = David
|last = Curtis
|coauthors = Fabryka-Martin, June; Paul, Dixon; Cramer, Jan
|bibcode=1999GeCoA..63..275C
}}</ref> Even smaller amounts of [[primordial nuclide|primordial]] plutonium-244 occur naturally due to its relatively long half-life of about 80&nbsp;million years.<ref>
{{cite journal
|first = D. C.
|last = Hoffman
|coauthors = Lawrence, F. O.; Mewherter, J. L.; and Rourke, F. M.
|title = Detection of Plutonium-244 in Nature
|journal = Nature
|id = Nr. 34
|year = 1971
|pages = 132–134
|doi = 10.1038/234132a0
|volume = 234
|bibcode = 1971Natur.234..132H
|issue=5325}}</ref> These trace amounts of <sup>239</sup>Pu originate in the following fashion: On rare occasions, <sup>238</sup>U undergoes spontaneous fission, and in the process, the nucleus emits one or two free neutrons with some kinetic energy. When one of these neutrons strikes the nucleus of another <sup>238</sup>U atom, it is absorbed by the atom, which becomes <sup>239</sup>U. With a relatively short half-life, U-239 decays to [[neptunium]]-239 (<sup>239</sup>Np), and then <sup>239</sup>Np decays into <sup>239</sup>Pu.
 
Since the relatively long-lived isotope plutonium-240 occurs in the [[thorium series#Thorium series|decay chain]] of plutonium-244 it should also be present, albeit 10,000 times rarer still. Finally, exceedingly small amounts of plutonium-238, attributed to the extremely rare [[double beta decay]] of uranium-238, have been found in natural uranium samples.<ref>{{cite news|author=Peterson, Ivars |title=Uranium displays rare type of radioactivity|publisher=Science News|date=December 7, 1991|url=http://findarticles.com/p/articles/mi_m1200/is_n23_v140/ai_11701241/}}</ref>
 
Minute traces of plutonium are usually found in the human body due to the 550 atmospheric and underwater [[nuclear testing|nuclear tests]] that have been carried out, and to a small number of major [[list of civilian nuclear accidents|nuclear accidents]]. Most atmospheric and underwater nuclear testing was stopped by the [[Limited Test Ban Treaty]] in 1963, which was signed and ratified by the United States, the United Kingdom, the [[Soviet Union]], and other nations. Continued atmospheric nuclear weapons testing since 1963 by non-treaty nations included those by [[China]] ([[atomic bomb]] test above the [[Gobi Desert]] in 1964, [[hydrogen bomb]] test in 1967, and follow-on tests), and France (tests as recently as the 1990s). Because it is deliberately manufactured for nuclear weapons and nuclear reactors, plutonium-239 is the most abundant isotope of plutonium by far.<ref name = "Emsley2001">{{harvnb|Emsley|2001}}</ref> <!-- NEEDS CITE It is also hypothetically possible for minute quantities of plutonium to be produced by the natural bombardment of uranium ores with [[cosmic ray]]s. -->
 
==History==
 
===Discovery===
[[Enrico Fermi]] and a team of scientists at the [[University of Rome La Sapienza|University of Rome]] reported that they had discovered element 94 in 1934.<ref>{{cite web
|url = http://www.nndc.bnl.gov/content/evaluation.html
|title = A Short History of Nuclear Data and Its Evaluation
|last = Holden|first = Norman E.
|publisher = National Nuclear Data Center, Brookhaven National Laboratory
|location = Upton (NY)
|work = 51st Meeting of the USDOE Cross Section Evaluation Working Group
|year = 2001
|accessdate = January 3, 2009
}}</ref> Fermi called the element ''[[hesperium]]'' and mentioned it in his Nobel Lecture in 1938.<ref>{{cite web
|url = http://www.nobel.se/physics/laureates/1938/fermi-lecture.pdf
|format = PDF
|last = Fermi|first = Enrico
|date = December 12, 1938
|title = Artificial radioactivity produced by neutron bombardment: Nobel Lecture
|publisher = Royal Swedish Academy of Sciences
}}</ref> The sample was actually a mixture of [[barium]], [[krypton]], and other elements, but this was not known at the time because [[nuclear fission]] had not been discovered yet.<ref>{{cite book
|url = http://www.philosophy.umd.edu/Faculty/LDarden/sciinq/
|title = The Nature of Scientific Inquiry
|last = Darden|first = Lindley
|chapter = Enrico Fermi: "Transuranium" Elements, Slow Neutrons
|publisher = Department of Philosophy, University of Maryland
|year = 1998
|accessdate = January 3, 2008
|location = College Park (MD)
}}</ref>
 
The breakthrough with plutonium was at the [[Cavendish Laboratory]], [[Cambridge]] by [[Egon Bretscher]] and [[Norman Feather]].
They realized that a slow neutron reactor fuelled with uranium would theoretically produce substantial amounts of plutonium-239 as a by-product. This is because U-238 absorbs [[slow neutron]]s and forms a new isotope U-239. The new isotope's nucleus rapidly emits an electron through [[beta decay]] producing a new element with a mass of 239 and an atomic number of 93. This element's nucleus then also emits an electron and becomes a new element of mass 239 but with an atomic number 94 and a much greater half-life. Bretscher and Feather showed theoretically feasible grounds that element 94 would be readily 'fissionable' by both slow and fast neutrons, and had the added advantage of being chemically different from uranium, and could easily be separated from it.
 
This new development was also confirmed in independent work by [[Edwin M. McMillan]] and [[Philip Abelson]] at [[Berkeley Radiation Laboratory]] also in 1940. [[Nicholas Kemmer]] of the Cambridge team proposed the names [[neptunium]] for the new element 93 and plutonium for 94 by analogy with the outer planets Neptune and Pluto beyond Uranus (uranium being element 92). The Americans fortuitously suggested the same names.
 
[[File:Glenn Seaborg - 1964.jpg|thumb|[[Glenn T. Seaborg]] and his team at Berkeley were the first to produce plutonium.|alt=Picture of an elderly man in a suit facing the left to the viewer.]]
Plutonium (specifically, plutonium-238) was first produced and isolated on December 14, 1940, and chemically identified on February 23, 1941, by Dr. [[Glenn T. Seaborg]], [[Edwin McMillan|Edwin M. McMillan]], [[Joseph W. Kennedy|J. W. Kennedy]], and [[Arthur Wahl|A. C. Wahl]] by [[deuteron]] bombardment of uranium in the {{convert|60|in|cm|sing = on|sp=us}} [[cyclotron]] at the [[University of California, Berkeley]].<ref>
{{cite web
|url = http://www.lbl.gov/LBL-PID/Nobelists/Seaborg/65th-anniv/14.html
|title = An Early History of LBNL: Elements 93 and 94
|accessdate = September 17, 2008
|author = Seaborg, Glenn T.
|publisher = Advanced Computing for Science Department, Lawrence Berkeley National Laboratory
}}</ref><ref>{{cite web|title=The plutonium story|author=Glenn T. Seaborg |publisher=Lawrence Berkeley Laboratory, University of California |id=LBL-13492, DE82 004551 |url=http://www.osti.gov/bridge/purl.cover.jsp?purl=/5808140-l5UMe1/}}</ref> In the 1940 experiment, [[neptunium]]-238 was created directly by the bombardment but decayed by [[beta emission]] with a half-life of a little over two days, which indicated the formation of element 94.<ref name = "Emsley2001"/>
 
A paper documenting the discovery was prepared by the team and sent to the journal ''[[Physical Review]]'' in March 1941.<ref name = "Emsley2001"/> The paper was withdrawn before publication after the discovery that an isotope of the new element (plutonium-239) could undergo nuclear fission in a way that might be useful in an [[atomic bomb]]. Publication was delayed until a year after the end of [[World War II]] due to security concerns.<ref name="Stwertka1998" />
 
Edwin McMillan had recently named the first transuranium element after the planet [[Neptune]] and suggested that element&nbsp;94, being the next element in the series, be named for what was then considered the next planet, [[Pluto]].<ref name="Heiserman1992"/><ref group = "note">This was not the first time somebody suggested that an element be named "plutonium." A decade after barium was discovered, a Cambridge University professor suggested it be renamed to "plutonium" because the element was not (as suggested by the [[Greek language|Greek]] root, ''barys'', it was named for) heavy. He reasoned that, since it was produced by the relatively new technique of [[electrolysis]], its name should refer to [[fire]]. Thus he suggested it be named for the Roman god of the underworld, [[Pluto (god)|Pluto]]. {{harv|Heiserman|1992}}<!-- Note: page 338 --></ref> Seaborg originally considered the name "plutium", but later thought that it did not sound as good as "plutonium."<ref name="Clark57">
{{cite journal
|last = Clark
|first = David L.
|coauthors = Hobart, David E.
|title = Reflections on the Legacy of a Legend: Glenn T. Seaborg, 1912–1999
|journal = Los Alamos Science
|volume = 26
|year = 2000
|pages = 56–61, on 57
|url = http://www.fas.org/sgp/othergov/doe/lanl/pubs/00818011.pdf
|format = PDF
|accessdate = February 15, 2009
}}</ref> He chose the letters "Pu" as a joke, which passed without notice into the periodic table.<ref group = "note">As one article puts it, referring to information Seaborg gave in a talk: "The obvious choice for the symbol would have been Pl, but facetiously, Seaborg suggested Pu, like the words a child would exclaim, 'Pee-yoo!' when smelling something bad. Seaborg thought that he would receive a great deal of flak over that suggestion, but the naming committee accepted the symbol without a word."
:{{cite journal
|first = David L.
|last = Clark
|coauthors = Hobart, David E.
|title = Reflections on the Legacy of a Legend: Glenn T. Seaborg, 1912–1999
|journal = Los Alamos Science
|volume = 26
|pages = 56–61, on 57
|year = 2000
|url = http://www.fas.org/sgp/othergov/doe/lanl/pubs/00818011.pdf
|format = PDF
|accessdate = February 15, 2009
}}</ref> Alternative names considered by Seaborg and others were "ultimium" or "extremium" because of the erroneous belief that they had found the last possible [[chemical element|element]] on the [[periodic table]].<ref>
{{cite web
|url = http://www.pbs.org/wgbh/pages/frontline/shows/reaction/interviews/seaborg.html
|title = Frontline interview with Seaborg
|publisher = Public Broadcasting Service
|author = PBS contributors
|work = Frontline
|year = 1997
|accessdate = December 7, 2008
}}</ref>
 
===Early research===
The basic chemistry of plutonium was found to resemble uranium after a few months of initial study.<ref name = "Emsley2001"/> Early research was continued at the secret [[Metallurgical Laboratory]] of the [[University of Chicago]]. On August 20, 1942, a trace quantity of this element was isolated and measured for the first time. About 50&nbsp;micrograms of plutonium-239 combined with uranium and fission products was produced and only about 1&nbsp;microgram was isolated.<ref name = "Miner1968p541">{{harvnb|Miner|1968|p = 541}}</ref><ref name = "seaborg">
{{cite web
|title = History of MET Lab Section C-I, April 1942--April 1943
|publisher = California Univ., Berkeley (USA). Lawrence Berkeley Lab.
|url = http://dx.doi.org/10.2172/7110621
|accessdate = September 25, 2013
|author = Glenn T. Seaborg
}}</ref> This procedure enabled chemists to determine the new element's atomic weight.<ref name = "uchicago">
{{cite web
|title = Room 405, George Herbert Jones Laboratory
|publisher = National Park Service
|url = http://tps.cr.nps.gov/nhl/detail.cfm?ResourceId=735&ResourceType=Building
|accessdate = December 14, 2008
|author = NPS contributors
}}</ref><ref group = "note">Room 405 of the [[George Herbert Jones Laboratory]], where the first isolation of plutonium took place, was named a [[National Historic Landmark]] in May 1967.</ref>
 
In November 1943 some [[plutonium trifluoride]] was reduced to create the first sample of plutonium metal: a few micrograms of metallic beads.<ref name = "Miner1968p541"/> Enough plutonium was produced to make it the first synthetically made element to be visible with the unaided eye.<ref name = "Miner1968p540">{{harvnb|Miner|1968|p = 540}}</ref>
 
The nuclear properties of plutonium-239 were also studied; researchers found that when it is hit by a neutron it breaks apart (fissions) by releasing more neutrons and energy. These neutrons can hit other atoms of plutonium-239 and so on in an exponentially fast [[nuclear chain reaction|chain reaction]]. This can result in an explosion large enough to destroy a city if enough of the isotope is concentrated to form a [[critical mass]].<ref name = "Emsley2001"/>
 
===Production during the Manhattan Project===
During World War II the U.S. government established the [[Manhattan Project]], which was tasked with developing an atomic bomb. The three primary research and production sites of the project were the plutonium production facility at what is now the [[Hanford Site]], the [[uranium enrichment]] facilities at [[Oak Ridge, Tennessee]], and the weapons research and design laboratory, now known as [[Los Alamos National Laboratory]].<ref>
{{cite web
|url = http://www.lanl.gov/history/road/siteselection.shtml
|author = LANL contributors
|work = LANL History
|title = Site Selection
|publisher = Los Alamos National Laboratory
|location = Los Alamos, New Mexico
|accessdate = December 23, 2008
}}</ref>
 
[[File:Hanford B Reactor.jpg|thumb|The Hanford [[B Reactor]] face under construction—the first plutonium-production reactor.|alt=A photo taken from a ceiling of a tall square industrial room. Cement walls have metal ladders and meshes. A dozen of people are engaged in some activities on the floor.]]
[[Image:Hanford N Reactor adjusted.jpg|thumb|right|The [[Hanford site]] represents two-thirds of the nation's high-level radioactive waste by volume. Nuclear reactors line the riverbank at the Hanford Site along the [[Columbia River]] in January 1960.]]
 
The first production reactor that made plutonium-239 was the [[X-10 Graphite Reactor]]. It went online in 1943 and was built at a facility in Oak Ridge that later became the [[Oak Ridge National Laboratory]].<ref name = "Emsley2001"/><ref group = "note">During the Manhattan Project, plutonium was also often referred to as simply "49": the number 4 was for the last digit in 94 (atomic number of plutonium), and 9 was for the last digit in plutonium-239, the weapon-grade fissile isotope used in nuclear bombs.
:{{Cite journal
|last = Hammel
|first = E.F.
|year = 2000
|title = The taming of "49"&nbsp; – Big Science in little time. Recollections of Edward F. Hammel, pp. 2–9. In: Cooper N.G. Ed. (2000). Challenges in Plutonium Science
|journal = Los Alamos Science
|volume = 26
|issue = 1
|pages = 2–9
|url = http://www.fas.org/sgp/othergov/doe/lanl/pubs/00818010.pdf
|accessdate = February 15, 2009
}}
:{{Cite journal
|last = Hecker
|first = S.S.
|year = 2000
|title = Plutonium: an historical overview. In: Challenges in Plutonium Science
|journal = Los Alamos Science
|volume = 26
|issue = 1
|pages = 1–2
|url = http://www.fas.org/sgp/othergov/doe/lanl/pubs/number26.htm
|accessdate = February 15, 2009
}}</ref>
 
On April 5, 1944, [[Emilio Segrè]] at Los Alamos received the first sample of reactor-produced plutonium from Oak Ridge.<ref name="AtomicTimeline">
{{cite web
|url = http://www.atomicheritage.org/index.php?option=com_content&task=view&id=288&Itemid=202
|title = Atomic History Timeline 1942–1944
|publisher = Atomic Heritage Foundation
|last = Sublette
|first = Carey
|location = Washington (DC)
|accessdate = December 22, 2008
}}</ref> Within ten days, he discovered that reactor-bred plutonium had a higher concentration of the isotope plutonium-240 than cyclotron-produced plutonium. Plutonium-240 has a high [[spontaneous fission]] rate, raising the overall background neutron level of the plutonium sample. The original [[gun-type fission weapon|gun-type]] plutonium weapon, code-named "[[Thin Man nuclear bomb|Thin Man]]", had to be abandoned as a result—the increased number of spontaneous neutrons meant that nuclear pre-detonation (a [[fizzle (nuclear test)|fizzle]]) would be likely.
 
The entire plutonium weapon design effort at Los Alamos was soon changed to the more complicated implosion device, code-named "[[Fat Man]]." With an implosion weapon, a solid (or, in later designs, hollow) [[plutonium pit|sphere of plutonium]] is compressed to a high density with explosive lenses—a technically more daunting task than the simple gun-type design, but necessary to use plutonium for weapons purposes. ([[Enriched uranium]], by contrast, can be used with either method.)<ref name="AtomicTimeline"/>
 
Construction of the Hanford [[B Reactor]], the first industrial-sized nuclear reactor for the purposes of material production, was completed in March 1945. B Reactor produced the fissile material for the plutonium weapons used during World War II.<ref group=note>The American Society of Mechanical Engineers (ASME) established B Reactor as a National Historic Mechanical Engineering Landmark in September 1976.
:{{cite book
|title = History of 100-B Area
|publisher = Westinghouse Hanford Company
|location = Richland, Washington
|id = WHC-EP-0273
|last = Wahlen
|first = R.K.
|year = 1989
|page = 1
|url = http://www.hanford.gov/doe/history/files/HistoryofBArea.pdf
|format = PDF
|accessdate = February 15, 2009
}}
In August 2008, B Reactor was designated a U.S. [[National Historic Landmark]].
:{{cite web|url=http://www.nps.gov/history/nr/listings/20080829.HTM |title=Weekly List Actions |accessdate=August 30, 2008|publisher= National Park Service |date=August 29, 2008 }}
</ref> B, D and F were the initial reactors built at Hanford, and six additional plutonium-producing reactors were built later at the site.<ref name=100B>
{{cite book
|title = History of 100-B Area
|publisher = Westinghouse Hanford Company
|location = Richland, Washington
|id = WHC-EP-0273
|last = Wahlen
|first = R.K.
|year = 1989
|pages = iv, 1
|url = http://www.hanford.gov/doe/history/files/HistoryofBArea.pdf
|format = PDF
|accessdate = February 15, 2009
}}</ref>
 
In the 2013 book, ''[[Plutopia|Plutopia: Nuclear Families, Atomic Cities, and the Great Soviet and American Plutonium Disasters]]'' (Oxford), [[Kate Brown (professor)|Kate Brown]] explores the health of affected citizens in the United States, and the “slow-motion disasters” that still threaten the environments where the plutonium production plants are located. According to Brown, the plants at Hanford (and Mayak in the USSR), over a period of four decades, “both released more than 200 million curies of radioactive isotopes into the surrounding environment -- twice the amount expelled in the [[Chernobyl disaster]] in each instance”.<ref name=katebr>{{cite web |url=http://hnn.us/article/153096 |title=Kate Brown: Nuclear "Plutopias" the Largest Welfare Program in American History |author=Robert Lindley |year=2013|work=History News Network }}</ref> Most of this [[radioactive contamination]] over the years were part of normal operations, but unforeseen accidents did occur and plant management kept this secret, as the pollution continued unabated. Even today, as pollution threats to health and the environment persist, the government keeps knowledge about the associated risks from the public.<ref name=katebr/>
 
In 2004, a [[safe]] was discovered during excavations of a burial trench at the [[Hanford nuclear site]]. Inside the safe were various items, including a large glass bottle containing a whitish slurry which was subsequently identified as the oldest sample of weapons-grade plutonium known to exist. Isotope analysis by [[Pacific Northwest National Laboratory]] indicated that the plutonium in the bottle was manufactured in the [[X-10 Graphite Reactor|X-10 reactor]] at [[Oak Ridge, Tennessee|Oak Ridge]] during 1944.<ref>{{cite news
| last = Rincon
| first = Paul
| title = BBC NEWS – Science & Environment – US nuclear relic found in bottle
| url = http://news.bbc.co.uk/2/hi/science/nature/7918618.stm
| accessdate = March 2, 2009
|date=March 2, 2009
| work=BBC News}}
</ref><ref>{{Cite journal
| last = Gebel
| first = Erika
| year = 2009
| title = Old plutonium, new tricks
| journal = Analytical Chemistry
| volume = 81
| issue = 5
| page = 1724
| doi = 10.1021/ac900093b
}}</ref><ref>
{{Cite journal
| last = Schwantes
| first = Jon M.
| coauthors = Matthew Douglas, Steven E. Bonde, James D. Briggs, Orville T. Farmer, Lawrence R. Greenwood, Elwood A. Lepel, Christopher R. Orton, John F. Wacker, Andrzej T. Luksic
| year = 2009
| title = Nuclear archeology in a bottle: Evidence of pre-Trinity U.S. weapons activities from a waste burial site
| journal = Analytical Chemistry
| volume = 81
| issue = 4
| pages = 1297–1306
| doi = 10.1021/ac802286a
| pmid = 19152306
}}</ref>
 
===Trinity and Fat Man atomic bombs===
[[File:Fission bomb assembly methods.svg|right|thumb|Because of the presence of plutonium-240 in reactor-bred plutonium, the implosion design was developed for the "[[Fat Man]]" and "[[Trinity test|Trinity]]" weapons|alt=Two diagrams of weapon assembly. Top: "gun-type assembly method"&nbsp;— an elliptical shell encloses conventional chemical explosives on the left, whose detonation affects sub-critical pieced of uranium-235 on the right. Bottom: "implosion assembly method"&nbsp;— a spherical shell encloses eight high-explosive charges which upon detonation compress a plutonium charge in the core.]]
 
The first atomic bomb test, codenamed [[Trinity test|"Trinity"]] and detonated on July 16, 1945, near [[Alamogordo, New Mexico]], used plutonium as its fissile material.<ref name = "Miner1968p541"/> The implosion design of "[[Trinity (nuclear test)#The gadget|the gadget]]", as the Trinity device was code-named, used conventional explosive lenses to compress a sphere of plutonium into a supercritical mass, which was simultaneously showered with neutrons from the [[Urchin (detonator)|"Urchin"]], an initiator made of [[polonium]] and [[beryllium]] ([[neutron source]]: [[Neutron source#Small sized devices|(α, n) reaction]]).<ref name = "Emsley2001"/> Together, these ensured a runaway chain reaction and explosion. The overall weapon weighed over 4 tonnes, although it used just 6.2&nbsp;kg of plutonium in its core.<ref>{{cite web
|first = Carey
|last = Sublette
|work = Nuclear Weapons Frequently Asked Questions, edition 2.18
|url = http://nuclearweaponarchive.org/Nwfaq/Nfaq8.html#nfaq8.1.1
|title = 8.1.1 The Design of Gadget, Fat Man, and "Joe 1" (RDS-1)
|accessdate = January 4, 2008
|date = July 3, 2007
|publisher = The Nuclear Weapon Archive
}}</ref> About 20% of the plutonium used in the Trinity weapon underwent fission, resulting in an explosion with an energy equivalent to approximately 20,000 [[TNT equivalent|tons of TNT]].<ref name="yield">{{cite book
|first = John
|last = Malik
|url = http://www.fas.org/sgp/othergov/doe/lanl/docs1/00313791.pdf
|title = The Yields of the Hiroshima and Nagasaki Explosions
|publisher = Los Alamos
|id = LA-8819
|date = September 1985
|page = Table VI
|accessdate = February 15, 2009
}}</ref><ref group="note" name="efficiency">The efficiency calculation is based on the fact that 1&nbsp;kg of plutonium-239 (or uranium-235) fissioning results in an energy release of approximately 17 [[kiloton|kt]], leading to a rounded estimate of 1.2&nbsp;kg plutonium actually fissioned to produce the 20 kt yield. On the figure of 1&nbsp;kg = 17 kt,
:{{cite web
|authorlink = Richard Garwin
|first = Richard
|last = Garwin
|url = http://www.fas.org/rlg/PNWM_UMich.pdf
|title = Proliferation of Nuclear Weapons and Materials to State and Non-State Actors: What It Means for the Future of Nuclear Power
|work = University of Michigan Symposium
|date = October 4, 2002
|publisher = Federation of American Scientists
|accessdate = January 4, 2009
}}</ref>
 
An identical design was used in the "[[Fat Man]]" atomic bomb dropped on [[Nagasaki]], [[Japan]], on August 9, 1945, killing 70,000 people and wounding another 100,000.<ref name = "Emsley2001"/> The "[[Little Boy]]" bomb dropped on [[Hiroshima]] three days earlier used [[uranium-235]], not plutonium. Japan capitulated on August 15 to General [[Douglas MacArthur]]. Only after the announcement of the first atomic bombs was the existence of plutonium made public.
 
===Cold War use and waste===
Large stockpiles of [[weapons-grade plutonium]] were built up by both the [[Soviet Union]] and the United States during the [[Cold War]]. The U.S. reactors at Hanford and the [[Savannah River Site]] in South Carolina produced 103&nbsp;tonnes,<ref>
{{cite book
|title = Historic American Engineering Record: B Reactor (105-B Building)
|author = DOE contributors
|publisher = U.S. Department of Energy
|url = http://www.fas.org/sgp/othergov/doe/pu50yb.html#ZZ13
|year = 2001
|location = Richland (WA)
|page = 110
|id = DOE/RL-2001-16
|accessdate = December 24, 2008
}}</ref> and an estimated 170&nbsp;tonnes of military-grade plutonium was produced in USSR.<ref>
{{cite conference
|title = Safeguarding nuclear weapons-usable materials in Russia
|url = http://docs.nrdc.org/nuclear/nuc_06129701a_185.pdf
|first = Thomas B.
|last = Cochran
|conference = International Forum on Illegal Nuclear Traffic
|publisher = Natural Resources Defense Council, Inc
|location = Washington (DC)
|year = 1997
|accessdate = December 21, 2008
}}</ref><ref group = note>Much of this plutonium was used to make the fissionable cores of a type of thermonuclear weapon employing the [[Teller–Ulam design]]. These so-called 'hydrogen bombs' are a variety of nuclear weapon that use a fission bomb to trigger the [[nuclear fusion]] of heavy [[hydrogen]] isotopes. Their destructive yield is commonly in the millions of tons of TNT equivalent compared with the thousands of tons of TNT equivalent of fission-only devices.{{harv|Emsley|2001}}</ref> Each year about 20&nbsp;tonnes of the element is still produced as a by-product of the [[nuclear power]] industry.<ref name = "CRC2006p4-27">{{harvnb|CRC|2006|pp = 4–27}}</ref> As much as 1000&nbsp;tonnes of plutonium may be in storage with more than 200&nbsp;tonnes of that either inside or extracted from nuclear weapons.<ref name = "Emsley2001"/>
[[SIPRI]] estimated the world plutonium [[stockpile]] in 2007 as about 500 tons, divided equally between weapon and civilian stocks.<ref>{{cite book|title=SIPRI Yearbook 2007: Armaments, Disarmament, and International Security|author=[[Stockholm International Peace Research Institute]]|publisher=[[Oxford University Press]]|year=2007|page=567|isbn=978-0-19-923021-1|issn=0953-0282|url=http://books.google.com/?id=2M0C6SERFG0C&pg=PA567}}</ref>
 
[[File:Yucca Mountain emplacement drifts.jpg|thumb|Proposed waste storage tunnel design for the [[Yucca Mountain nuclear waste repository]]|alt=A drawing showing a main tubular tunnel, connected on its side to three other tubular tunnels, all embedded in sand-like matter.]]
Since the end of the Cold War these stockpiles have become a focus of [[nuclear proliferation]] concerns. In the U.S., some plutonium extracted from dismantled nuclear weapons is melted to form glass logs of [[plutonium oxide]] that weigh two&nbsp;tonnes.<ref name = "Emsley2001"/> The glass is made of [[borosilicate]]s mixed with [[cadmium]] and [[gadolinium]].<ref group = note>[[Gadolinium zirconium oxide]] ({{chem|Gd|2|Zr|2|O|7}}) has been studied because it could hold plutonium for up to 30&nbsp;million years.{{harv|Emsley|2001}}</ref> These logs are planned to be encased in [[stainless steel]] and stored as much as {{convert|4|km|0|abbr=on}} underground in bore holes that will be back-filled with [[concrete]].<ref name = "Emsley2001"/> As of 2008, the only facility in the U.S. that was scheduled to store plutonium in this way was the [[Yucca Mountain nuclear waste repository]], which is about {{convert|100|mi|km|sp=us}} north-east of [[Las Vegas, Nevada]].<ref>{{cite web
|url= http://georgewbush-whitehouse.archives.gov/news/releases/2002/07/20020723-2.html
|archiveurl= http://web.archive.org/web/20080306193653/http://georgewbush-whitehouse.archives.gov/news/releases/2002/07/20020723-2.html
|archivedate= March 6, 2008
|title= President Signs Yucca Mountain Bill|publisher= Office of the Press Secretary, White House
|author = Press Secretary
|location = Washington (DC)
|date= July 23, 2002
|accessdate= January 4, 2009}}</ref> Local and state opposition to this plan delayed efforts to store nuclear waste at Yucca Mountain. In March 2010, the Department of Energy withdrew its license application for the Yucca Mountain repository "with prejudice" and eliminated funding for the Office of Civilian Radioactive Waste Management, which had managed the Yucca Mountain site for 25 years, canceling the program.<ref>{{cite web |url=http://www.energy.gov/news/8721.htm|date= March 3, 2010 |title= Department of Energy Files Motion to Withdraw Yucca Mountain License Application |publisher= Department of Energy}}</ref>
 
===Medical experimentation===
{{See also|Human radiation experiments|Albert Stevens}}
During and after the end of World War II, scientists working on the Manhattan Project and other nuclear weapons research projects conducted studies of the effects of plutonium on laboratory animals and human subjects.<ref name = "Injection"/> Animal studies found that a few milligrams of plutonium per kilogram of tissue is a lethal dose.<ref name="PuHealth"/><!-- Note: page 78 -->
 
In the case of human subjects, this involved injecting solutions containing (typically) five micrograms of plutonium into hospital patients thought to be either terminally ill, or to have a life expectancy of less than ten years either due to age or chronic disease condition.<ref name = "Injection"/> This was reduced to one microgram in July 1945 after animal studies found that the way plutonium distributed itself in bones was more dangerous than [[radium]].<ref name="PuHealth">{{cite journal
|title = Plutonium and Health: How great is the risk?
|journal = Los Alamos Science
|year = 2000
|issue = 26
|pages = 78–79
|last = Voelz
|first = George L.
|location = Los Alamos (NM)
|publisher = Los Alamos National Laboratory
}}</ref> Many of these experiments resulted in strong mutation. Most of the subjects, [[Eileen Welsome]] says, were  poor, powerless, and sick.<ref name=rc>R.C. Longworth. [http://intl-bos.sagepub.com/content/55/6/58.full.pdf+html Injected! Book review:The Plutonium Files: America's Secret Medical Experiments in the Cold War], ''[[The Bulletin of the Atomic Scientists]]'', Nov/Dec 1999, 55(6): 58-61.</ref>
 
From 1945 to 1947, eighteen human test subjects were injected with plutonium without [[informed consent]]. The tests were used to create diagnostic tools to determine the uptake of plutonium in the body in order to develop safety standards for working with plutonium.<ref name = "Injection">
{{cite journal
|journal = Los Alamos Science
|title = The Human Plutonium Injection Experiments
|url = http://library.lanl.gov/cgi-bin/getfile?23-09.pdf
|accessdate = June 6, 2006
|year = 1995
|first = William
|last = Moss
|coauthors = Eckhardt, Roger
|volume = 23
|pages = 188, 205, 208, 214
|format = PDF
|publisher = Los Alamos National Laboratory
}}</ref> Other experiments directed by the [[United States Atomic Energy Commission]] and the Manhattan Project continued into the 1970s. ''[[The Plutonium Files]]'' chronicles the lives of the subjects of the secret program by naming each person involved and discussing the ethical and medical research conducted in secret by the scientists and doctors. The episode is now considered to be a serious breach of [[medical ethics]] and of the [[Hippocratic Oath]].<ref>
{{cite journal
|last = Yesley
|first = Michael S.
|title = 'Ethical Harm' and the Plutonium Injection Experiments
|journal = Los Alamos Science
|volume = 23
|year = 1995
|pages = 280–283
|url = http://www.fas.org/sgp/othergov/doe/lanl/pubs/00326649.pdf
|format = PDF
|accessdate = February 15, 2009
}}</ref>
The government covered up most of these radiation mishaps until 1993, when President [[Bill Clinton]] ordered a change of policy and federal agencies then made available relevant records. The resulting investigation was undertaken by the president’s [[Advisory Committee on Human Radiation Experiments]], and it uncovered much of the material about plutonium research on humans. The committee issued a controversial 1995 report which said that "wrongs were committed" but it did not condemn those who perpetrated them.<ref name=rc/>
 
==Applications==
 
===Explosives===
[[File:Nagasakibomb.jpg|thumb|upright||The [[Atomic bombings of Hiroshima and Nagasaki|atomic bomb dropped on Nagasaki, Japan]] in 1945 had a plutonium core.|alt=Photo of an atomic explosion mushroom with a gray stem and white cap.]]
The isotope plutonium-239 is a key fissile component in [[nuclear weapon]]s, due to its ease of fission and availability. Encasing the bomb's [[plutonium pit]] in a [[nuclear weapon design|tamper]] (an optional layer of dense material) decreases the amount of plutonium needed to reach [[critical mass (nuclear)|critical mass]] by [[neutron reflector|reflecting escaping neutrons]] back into the plutonium core. This reduces the amount of plutonium needed to reach criticality from 16&nbsp;kg to 10&nbsp;kg, which is a sphere with a diameter of about {{convert|10|cm|0|sp=us}}.<ref>
{{cite book
|title = Physics for Radiation Protection
|last = Martin
|first = James E.
|year = 2000
|publisher = Wiley-Interscience
|isbn = 0-471-35373-6
|edition = 1st
|page = 532
}}</ref> This critical mass is about a third of that for uranium-235.<ref name = "Heiserman1992"/>
 
The "[[Fat Man]]"–type plutonium bombs produced during the [[Manhattan Project]] used explosive compression of plutonium to obtain significantly higher densities than normal, combined with a central neutron source to begin the reaction and increase efficiency. Thus only 6.2&nbsp;kg of plutonium was needed for an [[nuclear weapon yield|explosive yield]] equivalent to 20 kilotons of [[trinitrotoluene|TNT]].<ref name="yield"/><ref name = "FASdesign">
{{cite web
|url = http://www.fas.org/nuke/intro/nuke/design.htm
|title = Nuclear Weapon Design
|publisher = [[Federation of American Scientists]]
|year = 1998
|accessdate = December 7, 2008
|author = FAS contributors
}}</ref> (See also [[nuclear weapon design]].) Hypothetically, as little as 4&nbsp;kg of plutonium—and maybe even less—could be used to make a single atomic bomb using very sophisticated assembly designs.<ref name = "FASdesign"/>
 
===Mixed oxide fuel===
{{main|Nuclear reprocessing}}
 
[[Spent nuclear fuel]] from normal [[light water reactor]]s contains plutonium, but it is a mixture of plutonium-242, 240, 239 and 238. The mixture is not sufficiently enriched for efficient nuclear weapons, but can be used once as [[MOX fuel]]. Accidental [[neutron capture]] causes the amount of plutonium-242 and 240 to grow each time the plutonium is irradiated in a reactor with low-speed "thermal" neutrons, so that after the second cycle, the plutonium can only be consumed by [[fast neutron reactor]]s. If fast neutron reactors are not available (the normal case), excess plutonium is usually discarded, and forms the longest-lived component of nuclear waste. The desire to consume this plutonium and other [[transuranic]] fuels and reduce the radiotoxicity of the waste is the usual reason nuclear engineers give to make fast neutron reactors.
 
The most common chemical process, [[PUREX]] (''P''lutonium–''UR''anium ''EX''traction) [[nuclear reprocessing|reprocesses]] [[spent nuclear fuel]] to extract plutonium and uranium which can be used to form a mixed oxide "[[MOX fuel]]" for reuse in nuclear reactors. Weapons grade plutonium can be added to the fuel mix. MOX fuel is used in [[light water reactor]]s and consists of 60&nbsp;kg of plutonium per tonne of fuel; after four years, three-quarters of the plutonium is burned (turned into other elements).<ref name = "Emsley2001"/> [[Breeder reactor]]s are specifically designed to create more fissionable material than they consume.
 
MOX fuel has been in use since the 1980s and is widely used in Europe.<ref>
{{cite web
|author = WNA contributors
|url = http://www.world-nuclear.org/info/inf29.html
|title = Mixed Oxide (MOX) Fuel
|year = 2006
|location = London (UK)
|publisher = World Nuclear Association
|accessdate = December 14, 2008
}}</ref> In September 2000, the United States and the [[Russian Federation]] signed a Plutonium Management and Disposition Agreement by which each agreed to dispose of 34&nbsp;tonnes of weapon grade plutonium.<ref name = USMOX>
{{cite book
|title = Plutonium Storage at the Department of Energy's Savannah River Site: First Annual Report to Congress
|publisher = Defense Nuclear Facilities Safety Board
|year = 2004
|pages = A–1
|author = DNFSB staff
|url = http://www.hss.energy.gov/deprep/2004/fb04y28b.pdf
|format = PDF
|accessdate = February 15, 2009
|chapter = Public Law 107-314, Subtitle E
}} (public domain text)</ref> The [[U.S. Department of Energy]] plans to dispose of 34&nbsp;tonnes of weapon grade plutonium in the United States before the end of 2019 by converting the plutonium to a MOX fuel to be used in commercial nuclear power reactors.<ref name = USMOX/>
 
MOX fuel improves total burnup. A fuel rod is reprocessed after three years of use to remove waste products, which by then account for 3% of the total weight of the rods.<ref name = "Emsley2001"/> Any uranium or plutonium isotopes produced during those three years are left and the rod goes back into production.<ref group = note>Breakdown of plutonium in a spent nuclear fuel rod: plutonium-239 (~58%), 240 (24%), 241 (11%), 242 (5%), and 238 (2%). {{harv|Emsley|2001}}</ref> The presence of up to 1% [[gallium]] per mass in weapon grade [[plutonium-gallium alloy|plutonium alloy]] has the potential to interfere with long-term operation of a [[light water reactor]].<ref>
{{cite journal
|title = Thermochemical Behavior of Gallium in Weapons-Material-Derived Mixed-Oxide Light Water Reactor (LWR) Fuel
|first = Theodore M.
|last = Besmann
|journal = Journal of the American Ceramic Society
|volume = 81
|issue = 12
|pages = 3071–3076
|year = 2005
|url =
|doi = 10.1111/j.1151-2916.1998.tb02740.x
}}<!-- {{doi|10.1007/BF02881277}}--></ref>
 
Plutonium recovered from spent reactor fuel poses a less significant [[nuclear proliferation|proliferation]] hazard, because of excessive contamination with non-fissile [[plutonium-240]] and [[plutonium-242]]. Separation of the isotopes is not feasible. A dedicated reactor operating on very low [[burnup]] (hence minimal exposure of newly formed Pu-239 to additional neutrons which causes it to be transformed to heavier isotopes of plutonium) is generally required to produce material suitable for use in efficient [[nuclear weapons]]. While 'weapons-grade' plutonium is defined to contain at least 92% plutonium-239 (of the total plutonium), the United States have managed to detonate an [[reactor-grade plutonium nuclear test|under-20Kt device]] using plutonium believed to contain only about 85% plutonium-239, so called 'fuel-grade' plutonium.<ref name="inf15"/> The 'reactor grade' plutonium produced by a regular LWR burnup cycle typically contains less than 60% Pu-239, with up to 30% parasitic Pu-240/Pu-242, and 10–15% fissile Pu-241.<ref name="inf15"/> It's unknown if a device using plutonium obtained from reprocessed civil nuclear waste can be detonated, however such a device could hypothetically [[fizzle (nuclear test)|fizzle]] and spread radioactive materials over a large urban area. The [[IAEA]] conservatively classifies plutonium of all isotopic vectors as "direct-use" material, that is, "nuclear material that can be used for the manufacture of nuclear explosives components without transmutation or further enrichment".<ref name="inf15">{{cite web
|author=WNA contributors
|url=http://www.world-nuclear.org/info/inf15.html
|title=Plutonium
|publisher=World Nuclear Association
|date=March 2009
|accessdate=February 28, 2010
}}</ref>
 
[[Americium|<sup>241</sup>Am]] has recently been suggested for use as a denaturing agent in plutonium reactor fuel rods to further limit its proliferation potential.<ref>{{cite news|title = BGU combats nuclear proliferation|url = http://www.jpost.com/HealthAndSci-Tech/ScienceAndEnvironment/Article.aspx?id=134591| date=March 1, 2010|accessdate = March 5, 2009}}</ref>
 
===Power and heat source===
[[File:Plutonium pellet.jpg|thumb|A glowing cylinder of <sup>238</sup>PuO<sub>2</sub>|alt=A glowing cylinder standing in a circular pit.]]
The isotope [[plutonium-238]] has a half-life of 87.74&nbsp;years.<ref>{{cite web|url=http://www.ieer.org/ensec/no-3/puchange.html|title=Science for the Critical Masses: How Plutonium Changes with Time|publisher=Institute for Energy and Environmental Research}}</ref> It emits a large amount of [[thermal energy]] with low levels of both [[gamma]] rays/particles and [[spontaneous fission|spontaneous neutron]] rays/particles.<ref name="pumper">{{cite journal
|url = http://arq.lanl.gov/source/orgs/nmt/nmtdo/AQarchive/05spring/heart.html
|journal = Actinide Research Quarterly
|title = From heat sources to heart sources: Los Alamos made material for plutonium-powered pumper
|author = ARQ contributors
|location = Los Alamos (NM)
|publisher = Los Alamos National Laboratory
|issue = 1
|year = 2005
|accessdate = February 15, 2009
}}</ref> Being an alpha emitter, it combines high energy radiation with low penetration and thereby requires minimal shielding. A sheet of paper can be used to shield against the alpha particles emitted by plutonium-238. One [[kilogram]] of the isotope can generate about 570 watts of heat.<ref name = "Heiserman1992"/><ref name="pumper"/><!-- commented out "can generate 22&nbsp;million&nbsp;[[kilowatt-hour]]s of heat energy" as dubious, despite the ref., see talk -->
 
These characteristics make it well-suited for electrical power generation for devices which must function without direct maintenance for timescales approximating a human lifetime. It is therefore used in [[radioisotope thermoelectric generator]]s and [[radioisotope heater unit]]s such as those in the [[Cassini–Huygens|Cassini]], [[Voyager program|Voyager]], and [[New Horizons]] space probes.
 
The twin [[Voyager program|Voyager]] spacecraft were launched in 1977, each containing a 500 watt plutonium power source. Over 30 years later, each source is still producing about 300 watts which allows limited operation of each spacecraft.<ref>[http://voyager.jpl.nasa.gov/spacecraft/spacecraftlife.html Voyager-Spacecraft Lifetime]</ref> An earlier version of the same technology powered five [[ALSEP|Apollo Lunar Surface Experiment Packages]], starting with Apollo 12 in 1969.<ref name = "Emsley2001"/>
 
Plutonium-238 has also been used successfully to power artificial heart [[artificial pacemaker|pacemakers]], to reduce the risk of repeated surgery.<ref>
{{cite journal
|title = Trends in Cardiac Pacemaker Batteries
|author = Venkateswara Sarma Mallela; V. Ilankumaran; and N.Srinivasa Rao
|journal = Indian Pacing Electrophysiol
|year = 2004
|pages = 201–212
|issue = 4
|pmid = 16943934
|volume = 4
|pmc = 1502062}}</ref><ref>[http://www.orau.org/ptp/collection/Miscellaneous/pacemaker.htm Defunct pacemakers with Pu power source]</ref> It has been largely replaced by [[lithium]]-based [[primary cell]]s, but {{as of|2003|lc=on}} there were somewhere between 50 and 100 plutonium-powered pacemakers still implanted and functioning in living patients.<ref>
{{cite web
|url = http://www.orau.org/PTP/collection/Miscellaneous/pacemaker.htm
|title = Plutonium Powered Pacemaker
|location = Oak Ridge (TN)
|publisher = Orau.org
|year = 1974
|author = ORAU contributors
|accessdate = September 12, 2008
}}</ref> Plutonium-238 was studied as a way to provide supplemental heat to [[scuba diving]].<ref>{{cite journal
|url = http://oai.dtic.mil/oai/oai?verb=getRecord&metadataPrefix=html&identifier=AD0708680
|title = SEALAB III – Diver's Isotopic Swimsuit-Heater System
|last = Bayles
|first = John J.
|coauthors = Taylor, Douglas
|publisher = Naval Civil Engineering Lab
|location = Port Hueneme (CA)
|id = AD0708680
|year = 1970
}}</ref> Plutonium-238 mixed with beryllium is used to generate neutrons for research purposes.<ref name = "Emsley2001"/>
 
==Precautions==
{{See also|Plutonium in the environment}}
 
===Toxicity===
Isotopes and compounds of plutonium are radioactive and accumulate in [[bone marrow]]. Contamination by plutonium oxide has resulted from [[lists of nuclear disasters and radioactive incidents|nuclear disasters and radioactive incidents]], including military nuclear accidents where nuclear weapons have burned.<ref name = "ATSDR">
{{cite web
|author = ATSDR contributors
|publisher = U.S. Department of Health and Human Services, [[Agency for Toxic Substances and Disease Registry]] (ATSDR)
|url = http://www.atsdr.cdc.gov/toxprofiles/tp143.html
|title = Toxicological Profile for Plutonium, Draft for Public Comment
|year = 2007
|accessdate = May 22, 2008
}}</ref> Studies of the effects of these smaller releases, as well as of the widespread radiation poisoning sickness and death following the [[atomic bombings of Hiroshima and Nagasaki]], have provided considerable information regarding the dangers, symptoms and prognosis of [[radiation poisoning]], which in the case of the Japanese [[Hibakusha]]/survivors was largely unrelated to direct plutonium exposure.<ref>{{cite journal | pmid = 19454804 | doi=10.1088/0952-4746/29/2A/S04 | volume=29 | issue=2A | title=Cancer and non-cancer effects in Japanese atomic bomb survivors |date=June 2009 | journal=J Radiol Prot | pages=A43–59 | last1 = Little | first1 = M P|bibcode = 2009JRP....29...43L }}</ref>
 
During the decay of plutonium, three types of radiation are released—alpha, beta, and gamma. Alpha radiation can travel only a short distance and cannot travel through the outer, dead layer of human skin. Beta radiation can penetrate human skin, but cannot go all the way through the body. Gamma radiation can go all the way through the body.<ref>[http://www.atsdr.cdc.gov/substances/toxsubstance.asp?toxid=119 Plutonium], CAS ID #: 7440-07-5, [[Centers for Disease Control and Prevention]] (CDC) [[Agency for Toxic Substances and Disease Registry]]</ref> Alpha, beta, and gamma radiation are all forms of [[ionizing radiation]]. Either acute or longer-term exposure carries a danger of [[ionizing radiation#Biological effects|serious health outcomes]] including [[radiation sickness]], [[genetic damage]], [[cancer]], and death. The danger increases with the amount of exposure.
 
Even though alpha radiation cannot penetrate the skin, ingested or inhaled plutonium does irradiate internal organs.<ref name = "Emsley2001"/> The [[skeleton]], where plutonium accumulates, and the [[liver]], where it collects and becomes concentrated, are at risk.<ref name = "Miner1968p545"/> Plutonium is not absorbed into the body efficiently when ingested; only 0.04% of plutonium oxide is absorbed after ingestion.<ref name = "Emsley2001"/> Plutonium absorbed by the body is excreted very slowly, with a [[biological half-life]] of 200 years.<ref>
{{cite web
|author = DOE staff
|title = Radiological control technical training
|publisher = U.S. Department of Energy
|url = http://hss.energy.gov/NuclearSafety/techstds/standard/hdbk1122-04/part9of9.pdf
|archiveurl = http://web.archive.org/web/20070630190114/http://hss.energy.gov/NuclearSafety/techstds/standard/hdbk1122-04/part9of9.pdf
|archivedate = June 30, 2007
|accessdate = December 14, 2008
}}</ref> Plutonium passes only slowly through cell membranes and intestinal boundaries, so absorption by ingestion and incorporation into bone structure proceeds very slowly.<ref name="CohenMyth">{{cite web
|last = Cohen
|first = Bernard L.
|authorlink1 = Bernard Cohen (physicist)
|title = The Myth of Plutonium Toxicity
|url = http://web.archive.org/web/20110826115232/http://russp.org/BLC-3.html
}}</ref><ref>{{cite journal
|journal = The Radiation Safety Journal: Health Physics
|last = Cohen
|first = Bernard L.
|title = Hazards from Plutonium Toxicity
|date = May 1977
|volume = 32
|issue = 5
|pages = 359–379
|doi = 10.1097/00004032-197705000-00003}}</ref>
 
Plutonium is more dangerous when inhaled than when ingested. The risk of [[lung cancer]] increases once the total radiation [[equivalent dose|dose equivalent]] of inhaled plutonium exceeds 400 [[sievert|mSv]].<ref name="Brown">{{cite journal |last=Brown |first=Shannon C. |coauthors=Margaret F. Schonbeck, David McClure, et al. |title=Lung cancer and internal lung doses among plutonium workers at the Rocky Flats Plant: a case-control study |journal=American Journal of Epidemiology |volume=160 |issue=2 |pages=163–172 |publisher=Oxford Journals |date=July 2004 |url=http://aje.oxfordjournals.org/cgi/content/full/160/2/163|pmid=15234938 |accessdate=February 15, 2009 |doi=10.1093/aje/kwh192}}</ref> The U.S. Department of Energy estimates that the lifetime cancer risk from inhaling 5,000 plutonium particles, each about 3&nbsp;[[µm]] wide, to be 1% over the background U.S. average.<ref name="world-nuclear">{{cite web |author=ANL staff |url=http://www.evs.anl.gov/pub/doc/Plutonium.pdf|title=ANL human health fact sheet—plutonium|publisher=Argonne National Laboratory|year=2001|accessdate=June 16, 2007}}</ref> Ingestion or inhalation of large amounts may cause acute [[radiation poisoning]] and death; no human is known to have died because of inhaling or ingesting plutonium, and many people have measurable amounts of plutonium in their bodies.<ref name="inf15"/>
 
The "[[hot particle]]" theory in which a particle of plutonium dust radiates a localized spot of lung tissue is not supported by mainstream research — such particles are more mobile than originally thought and toxicity is not measurably increased due to particulate form.<ref name="CohenMyth"/>
 
When inhaled, plutonium can pass into the bloodstream. Once in the bloodstream, plutonium moves throughout the body and into the bones, liver, or other body organs. Plutonium that reaches body organs generally stays in the body for decades and continues to expose the surrounding tissue to radiation and thus may cause cancer.<ref name="EPA">{{cite web |title = Radiation Protection, Plutonium: What does plutonium do once it gets into the body? |publisher = U.S. Environmental Protection Agency |accessdate = March 15, 2011 |url = http://www.epa.gov/radiation/radionuclides/plutonium.html}}</ref>
 
A commonly cited quote by [[Ralph Nader]]<ref>{{cite web|title=Did Ralph Nader say that a pound of plutonium could cause 8 billion cancers?|url=http://skeptics.stackexchange.com/questions/18236/did-ralph-nader-say-that-a-pound-of-plutonium-could-cause-8-billion-cancers|accessdate=2013-01-03}}</ref> states that a pound of plutonium dust spread into the atmosphere would be enough to kill 8 billion people. However, calculations show that one pound of plutonium could kill no more than 2 million people by inhalation. This makes the toxicity of plutonium roughly equivalent with that of [[nerve gas]].<ref name=Cohen-13>{{cite web | url=http://www.phyast.pitt.edu/~blc/book/chapter13.html | author=Bernard L. Cohen | title=The Nuclear Energy Option, Chapter 13, Plutonium and Bombs | accessdate=2011-03-28}} (Online version of Cohen's book ''The Nuclear Energy Option'' (Plenum Press, 1990) ISBN 0-306-43567-5).</ref>  Nader's views were challenged in 1976 by [[Bernard Cohen (physicist)|Bernard Cohen]], as described in the book ''Nuclear Power, Both Sides: The Best Arguments for and Against the Most Controversial Technology''.  Cohen's own estimate is that a dose of 200 micrograms would likely be necessary to cause cancer.<ref>{{cite book|first1=Michio|last1=Kaku|first2=Jennifer |last2=Trainer|title=Nuclear Power, Both Sides: The Best Arguments for and Against the Most Controversial Technology|publisher=W. W. Norton & Company|year=1983|url=http://books.google.com/books?id=7A9A9BSk0eUC&lpg=PA77&ots=DwcBgEJjvc&pg=PA77#v=onepage&q=ralph%20nader%20microgram%20plutonium&f=false|accessdate=2013-12-08|page=77}}</ref>
 
Several populations of people who have been exposed to plutonium dust (e.g. people living down-wind of Nevada test sites, [[Hibakusha|Nagasaki survivors]], nuclear facility workers, and "terminally ill" patients injected with Pu in 1945–46 to study Pu metabolism) have been carefully followed and analyzed. These studies generally do not show especially high plutonium toxicity or plutonium-induced cancer results, such as [[Albert Stevens]] who survived into old age after being injected with plutonium.<ref name="CohenMyth"/> "There were about 25 workers from Los Alamos National Laboratory who inhaled a considerable amount of plutonium dust during 1940s; according to the hot-particle theory, each of them has a 99.5% chance of being dead from lung cancer by now, but there has not been a single lung cancer among them."<ref name=Cohen-13/><ref>{{cite journal
|last = Voelz
|first = G. L.
|title = What We Have Learned About Plutonium from Human Data
|journal = The Radiation Safety Journal Health Physics
|year = 1975
|page = 29
|url = http://journals.lww.com/health-physics/Abstract/1975/10000/What_We_Have_Learned_about_Plutonium_from_Human.11.aspx
}}</ref>
 
Plutonium has a metallic taste.<ref>
{{cite book
|last = Welsome
|first = Eileen
|title = The Plutonium Files: America's Secret Medical Experiments in the Cold War
|publisher = Random House
|year = 2000
|location = New York
|isbn = 0-385-31954-1
|page = 17}}</ref>
 
===Criticality potential===
[[File:Partially-reflected-plutonium-sphere.jpeg|thumb|A sphere of simulated plutonium surrounded by neutron-reflecting [[tungsten carbide]] blocks in a re-enactment of Harry Daghlian's 1945 experiment|alt=A stack of square metal plates with a side about 10 inches. In the 3-inch hole in the top plate there is a gray metal ball.]]
Toxicity issues aside, care must be taken to avoid the accumulation of amounts of plutonium which approach [[critical mass (nuclear)|critical mass]], particularly because plutonium's critical mass is only a third of that of uranium-235.<ref name = "Heiserman1992"/> A critical mass of plutonium emits lethal amounts of neutrons and [[gamma ray]]s.<ref name = "Miner1968p546">{{harvnb|Miner|1968|p = 546}}</ref> Plutonium in solution is more likely to form a critical mass than the solid form due to [[neutron moderator|moderation]] by the hydrogen in water.<ref name = "CRC2006p4-27"/>
 
[[Criticality accident]]s have occurred in the past, some of them with lethal consequences. Careless handling of [[tungsten carbide]] bricks around a 6.2&nbsp;kg plutonium sphere resulted in a fatal dose of radiation at [[Los Alamos National Laboratory|Los Alamos]] on August 21, 1945, when scientist [[Harry K. Daghlian, Jr.]] received a dose estimated to be 5.1&nbsp;[[Sievert]] (510&nbsp;[[Roentgen equivalent man|rems]]) and died 25&nbsp;days later.<ref>
{{cite book
|url = http://www.lanl.gov/news/index.php/fuseaction/home.story/story_id/1054/view/print
|title = Criticality accidents report issued
|publisher = Los Alamos National Laboratory
|location = Los Alamos (NM)
|accessdate = November 16, 2008
|year = 2000
|last = Roark|first = Kevin N.
|archiveurl = http://web.archive.org/web/20081008180945/http://lanl.gov/news/index.php/fuseaction/home.story/story_id/1054/view/print <!--Added by H3llBot-->
|archivedate = October 8, 2008
}}</ref><ref>{{cite book|last=Hunner|first=Jon|title=Inventing Los Alamos|year=2004|isbn=978-0-8061-3891-6|page=85}}</ref> Nine months later, another Los Alamos scientist, [[Louis Slotin]], died from a similar accident involving a beryllium reflector and the same plutonium core (the so-called "[[demon core]]") that had previously claimed the life of Daghlian.<ref>
{{cite web
|url = http://www.lanl.gov/history/people/R_Schreiber.shtml
|title = Raemer Schreiber
|work = Staff Biographies
|publisher = Los Alamos National Laboratory
|location = Los Alamos (NM)
|author = LANL contributors
|accessdate = November 16, 2008
|archiveurl = http://wayback.archive.org/web/20130103180527/http://www.lanl.gov/history/people/R_Schreiber.shtml
|archivedate= January 3, 2013
}}</ref> These incidents were fictionalized in the 1989 film ''[[Fat Man and Little Boy]]''.
 
In December 1958, during a process of purifying plutonium at Los Alamos, a critical mass was formed in a mixing vessel, which resulted in the death of a chemical operator named [[Cecil Kelley criticality accident|Cecil Kelley]].<ref name = "CriticalityAccidents">
{{cite journal
|url=http://www.csirc.net/docs/reports/la-13638.pdf
|title = A Review of Criticality Accidents
|id = LA-13638
|publisher = Los Alamos National Laboratory
|location = Los Alamos (NM)
|year = 2000
|page = 17
|last = McLaughlin
|first = Thomas P.
|coauthors = Monahan, Shean P.; Pruvost, Norman L.
}}</ref> Other [[nuclear and radiation accidents|nuclear accidents]] have occurred in the [[Soviet Union]], [[Japan]], the United States, and many other countries.<ref name = "CriticalityAccidents"/>
 
===Flammability===
Metallic plutonium is a fire hazard, especially if the material is finely divided. In a moist environment, plutonium forms hydrides on its surface, which are [[pyrophoricity|pyrophoric]] and may ignite in air at room temperature. Plutonium expands up to 70% in volume as it oxidizes and thus may break its container.<ref name = "NucSafety"/> The radioactivity of the burning material is an additional hazard. [[Magnesium oxide]] sand is probably the most effective material for extinguishing a plutonium fire. It cools the burning material, acting as a [[heat sink]], and also blocks off oxygen. Special precautions are necessary to store or handle plutonium in any form; generally a dry [[inert gas]] atmosphere is required.<ref name = "NucSafety">{{cite web|url = http://www.hss.energy.gov/NuclearSafety/techstds/standard/hdbk1081/hbk1081d.html#ZZ281|archiveurl = http://web.archive.org/web/20070428220410/http://www.hss.energy.gov/NuclearSafety/techstds/standard/hdbk1081/hbk1081d.html#ZZ281|archivedate = April 28, 2007|title = Primer on Spontaneous Heating and Pyrophoricity – Pyrophoric Metals – Plutonium|author = DOE contributors|publisher = U.S. Department of Energy, Office of Nuclear Safety, Quality Assurance and Environment|year = 1994|location = Washington (DC)}}</ref><ref group=note>There was a major plutonium-initiated fire at the [[Rocky Flats Plant]] near [[Boulder, Colorado|Boulder]], [[Colorado]] in 1969.
:{{cite web|first = David|last = Albright|coauthors = O'Neill, Kevin|year = 1999|url = http://www.isis-online.org/publications/usfacilities/Rfpbrf.html|title = The Lessons of Nuclear Secrecy at Rocky Flats|work = ISIS Issue Brief|accessdate = December 7, 2008|publisher = Institute for Science and International Security (ISIS)| archiveurl = http://web.archive.org/web/20080708220510/http://www.isis-online.org/publications/usfacilities/Rfpbrf.html| archivedate = July 8, 2008}}</ref>
 
==Transportation==
 
===Air===
{{Globalize|Section|date=August 2012}}
The U.S. Government air transport regulations permit the transport of plutonium by air, subject to restrictions on other dangerous materials carried on the same flight, packaging requirements, and stowage in the rearmost part of the aircraft.<ref>{{cite web|url=http://law.justia.com/cfr/title49/49-2.1.1.3.10.html#49:2.1.1.3.10.3.25.9|title=Part 175.704 Plutonium shipments|work=Code of Federal Regulations 49 — Transportation|accessdate=1 August 2012}}</ref>
 
In 2012 media revealed that plutonium has been flown out of Norway on commercial [[passenger airline]]s—around every other year—including one time in 2011.<ref name="klassekampen1">{{cite web|author=Av Ida Søraunet Wangberg og Anne Kari Hinna |url=http://klassekampen.no/60502/article/item/null/flyr-plutonium-med-rutefly |title=Klassekampen : Flyr plutonium med rutefly |publisher=Klassekampen.no |date= |accessdate=2012-08-13}}</ref> Regulations permit an airplane to transport 15 grams of fissionable material.<ref name="klassekampen1"/> Such plutonium transportation is without problems, according to a Senior Advisor (''seniorrådgiver'') at [[Statens strålevern]].<ref name="klassekampen1"/>
 
==See also==
* [[Nuclear engineering]]
* [[Nuclear fuel cycle]]
* [[Nuclear physics]]
* ''[[Plutopia]]''
{{Portal bar|Chemistry|Nuclear technology|Physics}}
 
==Notes==
 
===Footnotes===
{{Reflist|group=note}}
 
===Citations===
{{Reflist|colwidth=30em}}
 
==References==
<!-- Only list books (hence section title ("References"?)) used as references here -->
* <!-- CRC -->{{cite book
|author = CRC contributors
|title = Handbook of Chemistry and Physics
|editor = David R. Lide
|edition = 87th
|year = 2006
|publisher = CRC Press, Taylor & Francis Group
|location = Boca Raton (FL)
|isbn = 0-8493-0487-3
|ref = CITEREFCRC2006}}
* <!-- Em -->{{cite book
|title = Nature's Building Blocks: An A–Z Guide to the Elements
|last = Emsley
|first = John
|publisher = Oxford University Press
|year = 2001
|location = Oxford (UK)
|isbn = 0-19-850340-7
|chapter = Plutonium
|pages = 324–329
|ref = CITEREFEmsley2001}}
* <!-- Gr -->{{cite book
|last = Greenwood
|first = N. N.
|coauthors = Earnshaw, A.
|title = Chemistry of the Elements
|edition = 2nd
|publisher = Butterworth-Heinemann
|location = Oxford (UK)
|year = 1997
|isbn = 0-7506-3365-4
|page =
|ref = CITEREFGreenwood1997}}
* <!-- He -->{{cite book
|last = Heiserman
|first = David L.
|title = Exploring Chemical Elements and their Compounds
|location = New York (NY)
|year = 1992
|publisher = TAB Books
|isbn = 0-8306-3018-X
|chapter = Element 94: Plutonium
|pages = 337–340
|ref = CITEREFHeiserman1992
}}
* <!-- M -->{{cite book
|title = The Encyclopedia of the Chemical Elements
|publisher = Reinhold Book Corporation
|location = New York (NY)
|year = 1968
|editor = Clifford A. Hampel (editor)
|last = Miner
|first = William N.
|coauthors = Schonfeld, Fred W.
|chapter = Plutonium
|pages = 540–546
|ref = CITEREFMiner1968
|lccn = 68-29938
}}
* <!-- Sw -->{{cite book
|title = Guide to the Elements
|edition = Revised
|first = Albert
|last = Stwertka
|publisher = Oxford University Press
|year = 1998
|chapter = Plutonium
|pages =
|isbn = 0-19-508083-1
|location = Oxford (UK)
|ref = CITEREFStwertka1998
}}
 
==External links==
{{Commons|Plutonium}}
{{Wiktionary|plutonium}}
{{Spoken Wikipedia|Plutonium.ogg|2009-07-18}}
* {{cite web
|url = http://www.llnl.gov/csts/publications/sutcliffe/
|archiveurl = http://web.archive.org/web/20060929015050/http://www.llnl.gov/csts/publications/sutcliffe/
|archivedate = September 29, 2006
|title = A Perspective on the Dangers of Plutonium
|first = W.G.
|last = Sutcliffe
|coauthors = et al.
|publisher = [[Lawrence Livermore National Laboratory]]
|year = 1995
}}
* {{cite web| url = http://www.globalsecurity.org/wmd/library/report/crs/97-564.htm
|title = Nuclear Weapons: Disposal Options for Surplus Weapons-Usable Plutonium
|first = C.M.
|last = Johnson
|coauthors = Davis, Z.S.
|work = CRS Report for Congress # 97-564 ENR
|year = 1997
|accessdate = February 15, 2009
}}
* {{cite web
|url = http://www.ieer.org/fctsheet/pu-props.html
|title = Physical, Nuclear, and Chemical, Properties of Plutonium
|author = IEER contributors
|publisher = [[IEER]]
|year = 2005
|accessdate = February 15, 2009
}}
* {{cite web
|url = http://www.msm.cam.ac.uk/phase-trans/2006/Plutonium/Plutonium.html
|title = Plutonium crystallography
|last = Bhadeshia
|first = H.
}}
* {{cite journal
|url = http://discovermagazine.com/2005/nov/end-of-plutonium
|title = End of the Plutonium Age
|last = Samuels
|first = D.
|journal = Discover Magazine
|volume = 26|issue = 11
|year = 2005
}}
* {{cite web| url = http://www.fas.org/nuke/intro/nuke/plutonium.htm
|title = Plutonium production
|publisher = [[Federation of American Scientists]]
|first = J.
|last = Pike
|coauthors = Sherman, R.
|year = 2000
|accessdate = February 15, 2009
}}
* {{cite web
|url = http://nuclearweaponarchive.org/Library/Plutonium/
|title = Plutonium Manufacture and Fabrication
|publisher = Nuclearweaponarchive.org
|author = Nuclear Weapon Archive contributors
}}
* {{cite web
|url = http://www.nuclearfiles.org/menu/key-issues/nuclear-energy/issues/world-plutonium-inventories-ong.htm
|title = World Plutonium Inventories
|publisher = Nuclear Files.org
|first = C.
|last = Ong
|year = 1999
|accessdate = February 15, 2009
}}
* {{cite journal
|url = http://www.fas.org/sgp/othergov/doe/lanl/pubs/number26.htm
|title = Challenges in Plutonium Science
|journal = Los Alamos Science
|volume = I & II|issue = 26
|author = LANL contributors
|year = 2000
|accessdate = February 15, 2009
}}
* {{cite web
|url = http://toxnet.nlm.nih.gov/cgi-bin/sis/search/r?dbs+hsdb:@term+@na+@rel+plutonium,+radioactive
|title = Plutonium, Radioactive
|publisher = NLM Hazardous Substances Databank
|year =
|author= NLM contributors
|accessdate= February 15, 2009
}}
* {{cite web
|url = http://alsos.wlu.edu/qsearch.aspx?browse=science/Plutonium
|title = Annotated Bibliography on plutonium
|publisher = Alsos Digital Library for Nuclear Issues
|year =
|author = Alsos contributors
|accessdate = February 15, 2009
}}
* [http://www.rsc.org/chemistryworld/podcast/element.asp Chemistry in its element podcast] (MP3) from the [[Royal Society of Chemistry]]'s [[Chemistry World]]: [http://www.rsc.org/images/CIIE_plutonium_48kbps_tcm18-121120.MP3 Plutonium]
* [http://www.periodicvideos.com/videos/094.htm Plutonium] at ''[[The Periodic Table of Videos]]'' (University of Nottingham)
 
{{Nuclear Technology}}
{{compact periodic table}}
{{Plutonium compounds}}
{{Chemical elements named after places}}
{{featured article}}
 
[[Category:Actinides]]
[[Category:Carcinogens]]
[[Category:Chemical elements]]
[[Category:Nuclear materials]]
[[Category:Plutonium|*]]
[[Category:Synthetic elements]]
[[Category:Manhattan Project]]
 
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