View source for Isotopes of plutonium

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{{Infobox plutonium isotopes}}
[[Plutonium]] ({{sub|94}}Pu) is an [[artificial element]], except for trace quantities resulting from [[neutron capture]] by [[uranium]], and thus a [[standard atomic weight]] cannot be given. Like all artificial elements, it has no [[stable isotope]]s. It was synthesized long before being found in nature, the first [[isotope]] synthesized being {{sup|238}}Pu in 1940. Twenty-two plutonium [[radioisotope]]s have been characterized. The most stable are {{sup|244}}Pu with a [[half-life]] of 80.8 million years; {{sup|242}}Pu with a half-life of 373,300 years; and {{sup|239}}Pu with a half-life of 24,110 years; and {{sup|240}}Pu with a half-life of 6,560 years. This element also has eight [[meta state]]s; all have half-lives of less than one second.

The known isotopes of plutonium range from {{sup|226}}Pu to {{sup|247}}Pu. The primary [[decay mode]]s before the most stable isotope, {{sup|244}}Pu, are [[spontaneous fission]] and [[alpha decay]]; the primary mode after is [[beta emission]]. The primary [[decay product]]s before {{sup|244}}Pu are [[isotopes of uranium]] and [[isotopes of neptunium|neptunium]] (not considering [[fission product]]s), and the primary decay products after are [[isotopes of americium]].

== List of isotopes ==
{{Anchor|Plutonium-221|Plutonium-222|Plutonium-223|Plutonium-224|Plutonium-225|Plutonium-226}}

<!--Please delete anchor(s) from the list above or table below if adding a dedicated isotope section(s).-->

{{Isotopes table
|symbol=Pu
|refs=NUBASE2020, AME2020 II
|notes=m, unc(), mass#, spin(), spin#, daughter-st, daughter-nst, EC, SF, CD, IT
}}
|-id=Plutonium-226
| {{sup|226}}Pu<ref>{{Cite web |url=http://www1.jinr.ru/Preprints/2024/50(P7-2024-50).pdf |title=Свойства радиоактивного распада нового ядра <sup>227</sup>Pu |trans-title=Properties of Radioactive Decay of the New Nucleus <sup>227</sup>Pu |vauthors=Kuznetsova AA, Svirikhin AI, Isaev AV, Bychkov MA, Danilkin VD, Devarazha KM, Zamyatin NI, Izosimov IN, Liu Z, Malyshev ON, Mukhin RS, Popeko AG, Popov YA, Rachkov VA, Saylaubekov B, Sokol EA, Tezekbaeva MS, Ulanova II, Zhang FS, Chepigin VI, Chelnokov ML, Eremin AV |date=2024 |website=jinr.ru |publisher=[[Joint Institute for Nuclear Research]] |access-date=9 November 2024 |lang=ru}}</ref>
| style="text-align:right" | 94
| style="text-align:right" | 132
| 226.03825(22)#
| ≥1 ms
| α 
| {{sup|222}}U
| 0+
|
|-id=Plutonium-227
| {{sup|227}}Pu<ref>{{cite journal |last1=Yang |first1=H. B. |last2=Gan |first2=Z. G. |last3=Zhang |first3=Z. Y. |last4=Huang |first4=M. H. |last5=Ma |first5=L. |last6=Yang |first6=C. L. |last7=Zhang |first7=M. M. |last8=Tian |first8=Y. L. |last9=Wang |first9=Y. S. |last10=Wang |first10=J. G. |last11=Zhou |first11=H. B. |last12=Hua |first12=W. |last13=Wang |first13=J. Y. |last14=Qiang |first14=Y. H. |last15=Zhao |first15=Z. |last16=Huang |first16=X. Y. |last17=Wen |first17=X. J. |last18=Li |first18=Z. Y. |last19=Zhang |first19=H. T. |last20=Xu |first20=S. Y. |last21=Li |first21=Z. C. |last22=Zhou |first22=H. |last23=Zhang |first23=X. |last24=Zhu |first24=L. |last25=Wang |first25=Z. |last26=Guan |first26=F. |last27=Yang |first27=H. R. |last28=Huang |first28=W. X. |last29=Ren |first29=Z. Z. |last30=Zhou |first30=S. G. |last31=Xu |first31=H. S. |title=α decay of the new isotope Pu 227 |journal=Physical Review C |date=3 October 2024 |volume=110 |issue=4 |doi=10.1103/PhysRevC.110.044302}}</ref>
| style="text-align:right" | 94
| style="text-align:right" | 133
| 227.03947(11)#
| {{val|0.78|0.39|0.19|u=s}}
| α 
| {{sup|223}}U
| 5/2+#
| 
|-id=Plutonium-228
| {{sup|228}}Pu
| style="text-align:right" | 94
| style="text-align:right" | 134
| 228.038763(25)
| 2.1(13)&nbsp;s
| α 
| {{sup|224}}U
| 0+
| 
|-id=Plutonium-229
| rowspan=3|{{sup|229}}Pu
| rowspan=3 style="text-align:right" | 94
| rowspan=3 style="text-align:right" | 135
| rowspan=3|229.040145(65)
| rowspan=3|91(26)&nbsp;s
| α (~50%)
| {{sup|225}}U
| rowspan=3|3/2+#
| rowspan=3|
|-
| β{{sup|+}} (~50%)
| {{sup|229}}Np
|-
| [[spontaneous fission|SF]] (<7%)
| (various)
|-id=Plutonium-230
| rowspan=2|{{sup|230}}Pu
| rowspan=2 style="text-align:right" | 94
| rowspan=2 style="text-align:right" | 136
| rowspan=2|230.039648(16)
| rowspan=2|105(10)&nbsp;s
| α (>73%)<ref>{{cite journal |last1=Wilson |first1=G. L. |last2=Takeyama |first2=M. |last3=Andreyev |first3=A. N. |last4=Andel |first4=B. |last5=Antalic |first5=S. |last6=Catford |first6=W. N. |last7=Ghys |first7=L. |last8=Haba |first8=H. |last9=Heßberger |first9=F. P. |last10=Huang |first10=M. |last11=Kaji |first11=D. |last12=Kalaninova |first12=Z. |last13=Morimoto |first13=K. |last14=Morita |first14=K. |last15=Murakami |first15=M. |last16=Nishio |first16=K. |last17=Orlandi |first17=R. |last18=Smith |first18=A. G. |last19=Tanaka |first19=K. |last20=Wakabayashi |first20=Y. |last21=Yamaki |first21=S. |title=β -delayed fission of Am 230 |journal=Physical Review C |date=13 October 2017 |volume=96 |issue=4 |page=044315 |doi=10.1103/PhysRevC.96.044315 |language=en |issn=2469-9985|doi-access=free }}</ref>
| {{sup|226}}U
| rowspan=2|0+
| rowspan=2|
|-
| β{{sup|+}} (<27%)
| {{sup|230}}Np
|-id=Plutonium-231
| rowspan=2|{{sup|231}}Pu
| rowspan=2 style="text-align:right" | 94
| rowspan=2 style="text-align:right" | 137
| rowspan=2|231.041126(24)
| rowspan=2|8.6(5)&nbsp;min
| β{{sup|+}} (87%)
| {{sup|231}}Np
| rowspan=2|(3/2+)
| rowspan=2|
|-
| α (13%)
| {{sup|227}}U
|-id=Plutonium-232
| rowspan=2|{{sup|232}}Pu
| rowspan=2 style="text-align:right" | 94
| rowspan=2 style="text-align:right" | 138
| rowspan=2|232.041182(18)
| rowspan=2|33.7(5)&nbsp;min
| [[Electron capture|EC]] (>80%)
| {{sup|232}}Np
| rowspan=2|0+
| rowspan=2|
|-
| α (<20%)
| {{sup|228}}U
|-id=Plutonium-233
| rowspan=2|{{sup|233}}Pu
| rowspan=2 style="text-align:right" | 94
| rowspan=2 style="text-align:right" | 139
| rowspan=2|233.042997(58)
| rowspan=2|20.9(4)&nbsp;min
| β{{sup|+}} (99.88%)
| {{sup|233}}Np
| rowspan=2|5/2+#
| rowspan=2|
|-
| α (0.12%)
| {{sup|229}}U
|-id=Plutonium-234
| rowspan=2|{{sup|234}}Pu
| rowspan=2 style="text-align:right" | 94
| rowspan=2 style="text-align:right" | 140
| rowspan=2|234.0433175(73)
| rowspan=2|8.8(1)&nbsp;h
| EC (94%)
| {{sup|234}}Np
| rowspan=2|0+
| rowspan=2|
|-
| α (6%)
| {{sup|230}}U
|-id=Plutonium-235
| rowspan=2|{{sup|235}}Pu
| rowspan=2 style="text-align:right" | 94
| rowspan=2 style="text-align:right" | 141
| rowspan=2|235.045285(22)
| rowspan=2|25.3(5)&nbsp;min
| β{{sup|+}}
| {{sup|235}}Np
| rowspan=2|(5/2+)
| rowspan=2|
|-
| α (0.0028%)
| {{sup|231}}U
|-id=Plutonium-236
| rowspan=3|{{sup|236}}Pu
| rowspan=3 style="text-align:right" | 94
| rowspan=3 style="text-align:right" | 142
| rowspan=3|236.0460567(19)
| rowspan=3|2.858(8)&nbsp;y
| α<ref group="n">Theorized to also undergo β<sup>−</sup>β<sup>−</sup> decay to <sup>236</sup>U</ref>
| {{sup|232}}U
| rowspan=3|0+
| rowspan=3|
|-
| SF (1.9×10{{sup|−7}}%)
| (various)
|-
| [[Cluster decay|CD]] (2×10{{sup|−12}}%)
| '''{{sup|208}}Pb'''<br/>{{sup|28}}Mg
|-id=Plutonium-236m
| style="text-indent:1em" | {{sup|236m}}Pu
| colspan="3" style="text-indent:2em" | 1185.45(15)&nbsp;keV
| 1.2(3)&nbsp;μs
| [[Isomeric transition|IT]]
| {{sup|236}}Pu
| 5−
|
|-id=Plutonium-237
| rowspan=2|{{sup|237}}Pu
| rowspan=2 style="text-align:right" | 94
| rowspan=2 style="text-align:right" | 143
| rowspan=2|237.0484079(18)
| rowspan=2|45.64(4)&nbsp;d
| EC
| {{sup|237}}Np
| rowspan=2|7/2−
| rowspan=2|
|-
| α (0.0042%)
| {{sup|233}}U
|-id=Plutonium-237m1
| style="text-indent:1em" | {{sup|237m1}}Pu
| colspan="3" style="text-indent:2em" | 145.543(8)&nbsp;keV
| 180(20)&nbsp;ms
| IT
| {{sup|237}}Pu
| 1/2+
|
|-id=Plutonium-237m2
| style="text-indent:1em" | {{sup|237m2}}Pu
| colspan="3" style="text-indent:2em" | 2900(250)&nbsp;keV
| 1.1(1)&nbsp;μs
| SF
| (various)
|
|
|-
| rowspan=5|[[Plutonium-238|{{sup|238}}Pu]]
| rowspan=5 style="text-align:right" | 94
| rowspan=5 style="text-align:right" | 144
| rowspan=5|238.0495582(12)
| rowspan=5|87.7(1)&nbsp;y
| α
| {{sup|234}}U
| rowspan=5|0+
| rowspan=5|Trace<ref group=n>[[Double beta decay]] product of [[uranium-238|{{sup|238}}U]]</ref>
|-
| SF (1.9×10{{sup|−7}}%)
| (various)
|-
| CD (1.4×10{{sup|−14}}%)
| {{sup|206}}Hg<br>{{sup|32}}Si
|-
| CD (<6×10{{sup|−15}}%)
| {{sup|210}}Pb<br>{{sup|28}}Mg
|-
| CD (<6×10{{sup|−15}}%)
| '''{{sup|208}}Pb'''<br>{{sup|30}}Mg
|-
| rowspan=2|[[Plutonium-239|{{sup|239}}Pu]]<ref group="n" name="f">fissile nuclide</ref><ref group="n">Most useful isotope for nuclear weapons</ref>
| rowspan=2 style="text-align:right" | 94
| rowspan=2 style="text-align:right" | 145
| rowspan=2|239.0521616(12)
| rowspan=2|2.411(3)×10<sup>4</sup>&nbsp;y
| α
| '''''{{sup|235}}U'''''
| rowspan=2|1/2+
| rowspan=2|Trace<ref group=n>[[Neutron capture]] product of [[uranium-238|{{sup|238}}U]]</ref>
|-
| SF (3.1×10{{sup|−10}}%)
| (various)
|-id=Plutonium-239m1
| style="text-indent:1em" | {{sup|239m1}}Pu
| colspan="3" style="text-indent:2em" | 391.584(3)&nbsp;keV
| 193(4)&nbsp;ns
| IT
| <sup>239</sup>Pu
| 7/2−
|
|-id=Plutonium-239m2
| style="text-indent:1em" | {{sup|239m2}}Pu
| colspan="3" style="text-indent:2em" | 3100(200)&nbsp;keV
| 7.5(10)&nbsp;μs
| SF
| (various)
| (5/2+)
|
|-
| rowspan=3|[[plutonium-240|{{sup|240}}Pu]]
| rowspan=3 style="text-align:right" | 94
| rowspan=3 style="text-align:right" | 146
| rowspan=3|240.0538117(12)
| rowspan=3|6.561(7)×10{{sup|3}}&nbsp;y
| α
| {{sup|236}}U
| rowspan=3|0+
| rowspan=3|Trace<ref group=n>Intermediate decay product of [[plutonium-244|{{sup|244}}Pu]]</ref>
|-
| SF (5.796×10{{sup|−6}}%)
| (various)
|-
| CD (<1.3×10{{sup|−11}}%)
| {{sup|206}}Hg<br>{{sup|34}}Si
|-id=Plutonium-240m
| style="text-indent:1em" | {{sup|240m}}Pu
| colspan="3" style="text-indent:2em" | 1308.74(5)&nbsp;keV
| 165(10)&nbsp;ns
| IT
| <sup>240</sup>Pu
| 5−
|
|-
| rowspan=3|[[plutonium-241|{{sup|241}}Pu]]<ref group="n" name="f" />
| rowspan=3 style="text-align:right" | 94
| rowspan=3 style="text-align:right" | 147
| rowspan=3|241.0568497(12)
| rowspan=3|14.329(29)&nbsp;y
| β{{sup|−}}
| {{sup|241}}Am
| rowspan=3|5/2+
| rowspan=3|
|-
| α (0.00245%)
| {{sup|237}}U
|-
| SF (<2.4×10{{sup|−14}}%)
| (various)
|-id=Plutonium-241m1
| style="text-indent:1em" | {{sup|241m1}}Pu
| colspan="3" style="text-indent:2em" | 161.6853(9)&nbsp;keV
| 0.88(5)&nbsp;μs
| IT
| <sup>241</sup>Pu
| 1/2+
|
|-id=Plutonium-241m2
| style="text-indent:1em" | {{sup|241m2}}Pu
| colspan="3" style="text-indent:2em" | 2200(200)&nbsp;keV
| 20.5(22)&nbsp;μs
| SF
| (various)
|
|
|-
| rowspan=2|[[plutonium-242|{{sup|242}}Pu]]
| rowspan=2 style="text-align:right" | 94
| rowspan=2 style="text-align:right" | 148
| rowspan=2|242.0587410(13)
| rowspan=2|3.75(2)×10{{sup|5}}&nbsp;y
| α
| '''''{{sup|238}}U'''''
| rowspan=2|0+
| rowspan=2|
|-
| SF (5.510×10{{sup|−4}}%)
| (various)
|-id=Plutonium-243
| {{sup|243}}Pu<ref group="n" name="f" />
| style="text-align:right" | 94
| style="text-align:right" | 149
| 243.0620021(27)
| 4.9553(25)&nbsp;h
| β{{sup|−}}
| {{sup|243}}Am
| 7/2+
|
|-id=Plutonium-243m
| style="text-indent:1em" | {{sup|243m}}Pu
| colspan="3" style="text-indent:2em" | 383.64(25)&nbsp;keV
| 330(30)&nbsp;ns
| IT
| <sup>243</sup>Pu
| (1/2+)
|
|-
| rowspan=3|[[plutonium-244|{{sup|244}}Pu]]
| rowspan=3 style="text-align:right" | 94
| rowspan=3 style="text-align:right" | 150
| rowspan=3|244.0642044(25)
| rowspan=3|81.3(3)×10{{sup|7}}&nbsp;y
| α (99.88%)
| {{sup|240}}U
| rowspan=3|0+
| rowspan=3|Trace<ref group=n>Interstellar, some may also be [[primordial nuclide|primordial]] but such claims are disputed</ref>
|-
| SF (0.123%)
| (various)
|-
| [[Double beta decay|β{{sup|−}}β{{sup|−}}]] (<7.3×10{{sup|−9}}%)
| {{sup|244}}Cm
|-id=Plutonium-244m
| style="text-indent:1em" | {{sup|244m}}Pu
| colspan="3" style="text-indent:2em" | 1216.0(5)&nbsp;keV
| 1.75(12)&nbsp;s
| IT
| <sup>244</sup>Pu
| 8−
|
|-id=Plutonium-245
| {{sup|245}}Pu
| style="text-align:right" | 94
| style="text-align:right" | 151
| 245.067825(15)
| 10.5(1)&nbsp;h
| β{{sup|−}}
| {{sup|245}}Am
| (9/2−)
|
|-id=Plutonium-245m1
| style="text-indent:1em" | {{sup|245m1}}Pu
| colspan="3" style="text-indent:2em" | 264.5(3)&nbsp;keV
| 330(20)&nbsp;ns
| IT
| <sup>245</sup>Pu
| (5/2+)
|
|-id=Plutonium-245m2
| style="text-indent:1em" | {{sup|245m2}}Pu
| colspan="3" style="text-indent:2em" | 2000(400)&nbsp;keV
| 90(30)&nbsp;ns
| SF
| (various)
| 
|
|-id=Plutonium-246
| {{sup|246}}Pu
| style="text-align:right" | 94
| style="text-align:right" | 152
| 246.070204(16)
| 10.84(2)&nbsp;d
| β{{sup|−}}
| {{sup|246}}Am
| 0+
|
|-id=Plutonium-247
| {{sup|247}}Pu
| style="text-align:right" | 94
| style="text-align:right" | 153
| 247.07430(22)#
| 2.27(23)&nbsp;d
| β{{sup|−}}
| {{sup|247}}Am
| 1/2+#
|
{{Isotopes table/footer}}

==Actinides vs fission products==
{{Actinidesvsfissionproducts}}
{{Clear}}

== Notable isotopes ==
*[[Plutonium-238]] has a half-life of 87.74 years<ref>{{cite magazine|last1=Makhijani|first1=Arjun|last2=Seth|first2=Anita|date=July 1997|title=The Use of Weapons Plutonium as Reactor Fuel|url=http://ieer.org/wp/wp-content/uploads/1997/07/no-3.pdf|magazine=Energy and Security|location=Takoma Park, MD|publisher=Institute for Energy and Environmental Research|access-date=4 July 2016}}</ref> and emits [[alpha particle]]s. Pure {{sup|238}}Pu for [[radioisotope thermoelectric generator]]s that power some [[spacecraft]] is produced by neutron capture on [[neptunium-237]] but plutonium from [[spent nuclear fuel]] can contain as much as a few percent {{sup|238}}Pu, originating from {{sup|237}}Np, [[alpha decay]] of {{sup|242}}Cm, or (n,2n) reactions.
*[[Plutonium-239]] has half-life 24,100 years. {{sup|239}}Pu and {{sup|241}}Pu are [[fissile]]; meaning their nuclei can [[nuclear fission|split]] by being bombarded by [[neutron temperature|slow]] thermal neutrons, releasing energy, [[gamma radiation]] and [[neutron radiation|more neutrons]]. It can therefore sustain a [[nuclear chain reaction]], leading to applications in [[nuclear weapon]]s and [[nuclear reactor]]s. {{sup|239}}Pu is synthesized by irradiating [[uranium-238]] with neutrons in a nuclear reactor, then recovered via [[nuclear reprocessing]] of the fuel. Further [[neutron capture]] produces successively heavier isotopes.
*[[Plutonium-240]] has a high rate of spontaneous fission, raising the background [[neutron radiation]] of plutonium. Plutonium is graded by proportion of {{sup|240}}Pu: [[weapons grade]] (<7%), [[fuel grade]] (7–19%) and [[reactor grade]] (>19%). Lower grades are less suited for bombs and [[thermal reactor]]s but can fuel [[fast reactor]]s.
*[[Plutonium-241]] is fissile, but [[beta decay]]s with a half-life of 14 years to [[americium-241]].
*[[Plutonium-242]] is not fissile, nor very fertile (requiring 3 more neutron captures to become fissile); and has a low neutron capture [[Neutron cross-section|cross section]], and a longer half-life than any of the lighter isotopes.
*[[Plutonium-244]] is the most stable isotope of plutonium, with a half-life of about 80&nbsp;million years. It is not significantly produced in nuclear reactors because {{sup|243}}Pu has a short half-life, but some is produced in nuclear explosions. {{sup|244}}Pu has been found in interstellar space<ref name="WallnerFaestermann2015">{{cite journal |last1=Wallner |first1=A. |last2=Faestermann |first2=T. |last3=Feige |first3=J. |last4=Feldstein |first4=C. |last5=Knie |first5=K. |last6=Korschinek |first6=G. |last7=Kutschera |first7=W. |last8=Ofan |first8=A. |last9=Paul |first9=M. |last10=Quinto |first10=F. |last11=Rugel |first11=G. |last12=Steier |first12=P. |title=Abundance of live 244Pu in deep-sea reservoirs on Earth points to rarity of actinide nucleosynthesis|journal=Nature Communications |volume=6 |year=2015 |pages=5956 |issn=2041-1723 |doi=10.1038/ncomms6956 |pmid=25601158 |pmc=4309418 |arxiv=1509.08054 |bibcode=2015NatCo...6.5956W}}</ref> and has the second longest half-life of any non-primordial radioisotope.

==Production and uses==
[[File:Plutonium pellet.jpg|right|thumb|A pellet of {{sup|238}}Pu, glowing from its own heat, used for [[radioisotope thermoelectric generator]]s.]]
[[File:Sasahara.svg|thumb|upright=1.5|[[Nuclear transmutation|Transmutation]] flow between {{sup|238}}Pu and {{sup|244}}Cm in [[Light water reactor|LWR]].<ref>{{cite journal|title=Neutron and Gamma Ray Source Evaluation of LWR High Burn-up UO2 and MOX Spent Fuels |journal=Journal of Nuclear Science and Technology |volume=41 |issue=4 |pages=448–456 |date=April 2004 |doi=10.3327/jnst.41.448 |last1=Sasahara |first1=Akihiro |last2=Matsumura |first2=Tetsuo |last3=Nicolaou |first3=Giorgos |last4=Papaioannou |first4=Dimitri |doi-access=free }}</ref><br/>Transmutation speed not shown and varies greatly by nuclide. {{sup|245}}Cm&ndash;{{sup|248}}Cm are long-lived with negligible decay.]]
{{sup|239}}Pu, a fissile isotope that is the second most used [[nuclear fuel]] in nuclear reactors after [[uranium-235]], and the most used fuel in the [[Nuclear fission|fission]] portion of [[nuclear weapon]]s, is produced from [[uranium-238]] by neutron capture followed by two beta decays.

{{sup|240}}Pu, {{sup|241}}Pu, and {{sup|242}}Pu are produced by further neutron capture. The odd-mass isotopes {{sup|239}}Pu and {{sup|241}}Pu have about a 3/4 chance of undergoing fission on capture of a [[thermal neutron]] and about a 1/4 chance of retaining the [[neutron]] and becoming the next heavier isotope. The even-mass isotopes are [[fertile material|fertile]] but not fissile and also have a lower probability ([[Neutron cross-section|cross section]]) of neutron capture; therefore, they tend to accumulate in nuclear fuel used in a thermal reactor, the design of nearly all [[nuclear power plant]]s today. In plutonium that has been used a second time in thermal reactors in [[MOX fuel]], {{sup|240}}Pu may even be the most common isotope. All plutonium isotopes and other [[actinide]]s, however, are [[fissionable]] with [[fast neutron]]s. {{sup|240}}Pu does have a moderate thermal neutron absorption cross section, so that {{sup|241}}Pu production in a thermal reactor becomes a significant fraction as large as {{sup|239}}Pu production.

{{sup|241}}Pu has a half-life of 14 years, and has slightly higher thermal neutron cross sections than {{sup|239}}Pu for both fission and absorption. While nuclear fuel is being used in a reactor, a {{sup|241}}Pu nucleus is much more likely to fission or to capture a neutron than to decay. {{sup|241}}Pu accounts for a significant portion of fissions in thermal reactor fuel that has been used for some time. However, in [[spent nuclear fuel]] that does not quickly undergo nuclear reprocessing but instead is cooled for years after use, much or most of the {{sup|241}}Pu will beta decay to [[americium-241]], one of the [[minor actinide]]s, a strong alpha emitter, and difficult to use in thermal reactors.

{{sup|242}}Pu has a particularly low cross section for thermal neutron capture; and it takes three neutron absorptions to become another fissile isotope (either [[curium]]-245 or {{sup|241}}Pu) and fission. Even then, there is a chance either of those two fissile isotopes will fail to fission but instead absorb a fourth neutron, becoming curium-246 (on the way to even heavier actinides like [[californium]], which is a neutron emitter by spontaneous fission and difficult to handle) or becoming {{sup|242}}Pu again; so the mean number of neutrons absorbed before fission is even higher than 3. Therefore, {{sup|242}}Pu is particularly unsuited to recycling in a thermal reactor and would be better used in a [[fast reactor]] where it can be fissioned directly. However, {{sup|242}}Pu's low cross section means that relatively little of it will be transmuted during one cycle in a thermal reactor. {{sup|242}}Pu's half-life is about 15 times as long as {{sup|239}}Pu's half-life; therefore, it is 1/15 as radioactive and not one of the larger contributors to [[nuclear waste]] radioactivity.
{{sup|242}}Pu's [[gamma ray]] emissions are also weaker than those of the other isotopes.<ref>{{cite web|url=http://www.wmsym.org/archives/2001/21B/21B-18.pdf|title=Plutonium Isotopic Results of Known Samples Using the Snap Gamma Spectroscopy Analysis Code and the Robwin Spectrum Fitting Routine|access-date=2013-03-15|archive-date=2017-08-13|archive-url=https://web.archive.org/web/20170813191754/http://www.wmsym.org/archives/2001/21B/21B-18.pdf|url-status=dead}}</ref>

{{sup|243}}Pu has a half-life of only 5 hours, beta decaying to [[americium-243]]. Because {{sup|243}}Pu has little opportunity to capture an additional neutron before decay, the [[nuclear fuel cycle]] does not produce the long-lived {{sup|244}}Pu in significant quantity.

{{sup|238}}Pu is not normally produced in as large quantity by the nuclear fuel cycle, but some is produced from [[neptunium-237]] by neutron capture (this reaction can also be used with purified neptunium to produce {{sup|238}}Pu relatively free of other plutonium isotopes for use in [[radioisotope thermoelectric generator]]s), by the (n,2n) reaction of fast neutrons on {{sup|239}}Pu, or by alpha decay of [[curium]]-242, which is produced by neutron capture of {{sup|241}}Am. It has significant thermal neutron cross section for fission, but is more likely to capture a neutron and become {{sup|239}}Pu.

==Manufacture==<!-- This section is linked from [[Radioactive waste]] -->

===Plutonium-240, -241 and -242===

The fission [[Cross section (physics)|cross section]] for {{sup|239}}Pu is 747.9 [[Barn (unit)|barns]] for thermal neutrons, while the activation cross section is 270.7 barns (the ratio approximates to 11 fissions for every 4 neutron captures). The higher plutonium isotopes are created when the uranium fuel is used for a long time. For high burnup used fuel, the concentrations of the higher plutonium isotopes will be higher than the low burnup fuel that is reprocessed to obtain [[weapons grade]] plutonium.

{| class="wikitable"
|+ The formation of <sup>240</sup>Pu, <sup>241</sup>Pu, and <sup>242</sup>Pu from <sup>238</sup>U
!rowspan="2"| Isotope !!colspan="2"|Thermal neutron<br/>cross section<ref>[[National Nuclear Data Center]] [http://www.nndc.bnl.gov/chart/ Interactive Chart of Nuclides] {{Webarchive|url=https://web.archive.org/web/20110721051025/http://www.nndc.bnl.gov/chart/ |date=2011-07-21 }}</ref><br/>(barns) !!rowspan="2"| Decay<br/>Mode !! rowspan="2"|Half-life
|-
! Capture !! Fission
|-
| [[uranium-238|<sup>238</sup>U]] || 2.683 || 0.000 || α || 4.468 x 10<sup>9</sup> years
|-
| [[uranium-239|<sup>239</sup>U]] || 20.57 || 14.11 || β<sup>−</sup> || 23.45 minutes
|-
| [[neptunium-239|<sup>239</sup>Np]] || 77.03 || – || β<sup>−</sup> || 2.356 days
|-
| [[plutonium-239|<sup>239</sup>Pu]] || 270.7 || 747.9 || α || 24,110 years
|-
| [[plutonium-240|<sup>240</sup>Pu]] || 287.5 || 0.064 || α || 6,561 years
|-
| [[plutonium-241|<sup>241</sup>Pu]] || 363.0 || 1012 || β<sup>−</sup> || 14.325 years
|-
| [[plutonium-242|<sup>242</sup>Pu]] || 19.16 || 0.001 || α || 373,300 years
|}

===Plutonium-239===
{{Main|Plutonium-239}}
[[File:Plutonium ring.jpg|right|upright=1.35|thumb|A 5.3 kg ring of weapons-grade electrorefined plutonium, 99.96% purity. This is enough plutonium for an efficient nuclear weapon. The ring shape is needed to depart from a spherical shape and avoid [[critical mass|criticality]].]]
{{sup|239}}Pu is one of the three fissile materials used for the production of nuclear weapons and in some nuclear reactors as a source of energy. The other fissile materials are [[uranium-235]] and [[uranium-233]]. {{sup|239}}Pu is virtually nonexistent in nature. It is made by bombarding [[uranium-238]] with neutrons. Uranium-238 is present in quantity in most reactor fuel; hence {{sup|239}}Pu is continuously made in these reactors. Since {{sup|239}}Pu can itself be split by neutrons to release energy, {{sup|239}}Pu provides a portion of the energy generation in a nuclear reactor.

{| class="wikitable"
|+ The formation of {{sup|239}}Pu from {{sup|238}}U<ref name="Miner1968p541">{{harvnb|Miner|1968|p=541}}</ref>
! Element !! Isotope !! Thermal neutron capture<br/>cross section (barn) !! Thermal neutron fission <br/>Cross section (barn) !! decay mode !! Half-life
|-
! [[uranium|U]]
| 238 || 2.68 || 5·10{{sup|−6}} || α || 4.47 x 10{{sup|9}} years
|-
! [[uranium|U]]
| 239 || 22 || 15 || β{{sup|−}} || 23 minutes
|-
! [[neptunium|Np]]
| 239 || 30 || 1 || β{{sup|−}} || 2.36 days
|-
! [[plutonium|Pu]]
| 239 || 271 || 750 || α || 24,110 years
|}

===Plutonium-238===
{{Main|Plutonium-238}}
There are small amounts of {{sup|238}}Pu in the plutonium from usual reactors. However, isotopic separation would be quite expensive compared to another method: when {{sup|235}}U captures a neutron, it is converted to an excited state of {{sup|236}}U. Some of the excited {{sup|236}}U nuclei undergo fission, but some decay to the ground state of {{sup|236}}U by emitting gamma radiation. Further neutron capture creates {{sup|237}}U; which, with a half-life of 7 days, decays to {{sup|237}}Np. Since nearly all neptunium is produced in this way or consists of isotopes that decay quickly, one gets nearly pure {{sup|237}}Np. After chemical separation of neptunium, {{sup|237}}Np is again irradiated by reactor neutrons to be converted to {{sup|238}}Np, which decays to {{sup|238}}Pu with a half-life of 2 days.

{| class="wikitable"
|+ The formation of {{sup|238}}Pu from {{sup|235}}U
! Element !! Isotope !! Thermal neutron<br/>cross section !! decay mode !! Half-life
|-
! [[uranium|U]]
| 235 || 99 || α || 703,800,000 years
|-
! [[uranium|U]]
| 236 || 5.3 || α || 23,420,000 years
|-
! [[uranium|U]]
| 237 || — || β{{sup|−}} || 6.75 days
|-
! [[neptunium|Np]]
| 237 || 165 (capture) || α || 2,144,000 years
|-
! [[neptunium|Np]]
| 238 || — || β{{sup|−}} || 2.11 days
|-
! [[plutonium|Pu]]
| 238 || — || α || 87.7 years
|}

==Plutonium-240 as an obstacle to nuclear weapons==
{{sup|240}}Pu undergoes [[spontaneous fission]] at a small but significant rate ({{val|5.8|e=-6}}%).{{NUBASE2020|ref}} The presence of {{sup|240}}Pu limits the plutonium's use in a [[nuclear bomb]], because a neutron from spontaneous fission starts the [[chain reaction]] prematurely, causing an early release of energy that disperses the core before full [[implosion (mechanical process)|implosion]] is reached. This prevents most of the core from participation in the chain reaction and reduces the bomb's yield.

Plutonium consisting of more than about 90% {{sup|239}}Pu is called [[weapons-grade plutonium]]; plutonium from [[spent nuclear fuel]] from commercial power reactors generally contains at least 20% {{sup|240}}Pu and is called [[reactor-grade plutonium]]. However, modern nuclear weapons use [[fusion boosting]], which mitigates the predetonation problem; if the [[pit (nuclear weapon)|pit]] can generate a [[nuclear weapon yield]] of even a fraction of a [[kiloton]], which is enough to start [[nuclear fusion|deuterium–tritium fusion]], the resulting burst of neutrons will fission enough plutonium to ensure a yield of tens of kilotons.

Contamination due to {{sup|240}}Pu is the reason plutonium weapons must use the [[Nuclear weapon design#Implosion-type weapon|implosion method]]. Theoretically, pure {{sup|239}}Pu could be used in a [[gun-type bomb]], but achieving this level of purity is prohibitively difficult. {{sup|240}}Pu contamination has proven a mixed blessing. While it created delays and headaches during the [[Manhattan Project]] because of the need to develop implosion technology, those same difficulties are a barrier to [[nuclear proliferation]]. Implosion bombs are also inherently more efficient and less prone to accidental detonation than are gun-type bombs.

== References ==
* Isotope masses from:
**{{NUBASE 2003 |ref=none}}
* Half-life, spin, and isomer data selected from the following sources.
**{{NUBASE 2003 |ref=none}}
**{{NNDC |ref=none}}
**{{CRC85|chapter=11 |ref=none}}

{{Reflist}}

==Sources==
* {{Cite book |url=https://www-nds.iaea.org/publications/indc/indc_usa_0085_II.pdf |title=Proceedings of the conference on nuclear data evaluation methods and procedures. BNL-NCS 51363. |date=1981 |publisher=[[Brookhaven National Laboratory]] |editor-last=Magurno |editor-first=B. A. |volume=II |location=Upton |access-date=August 6, 2014 |editor-last2=Pearlstein |editor-first2=S. |archive-url=https://web.archive.org/web/20210308125416/https://www-nds.iaea.org/publications/indc/indc_usa_0085_II.pdf |archive-date=March 8, 2021 |url-status=live}}
* {{Cite book |last1=Miner |first1=William N. |title=The Encyclopedia of the Chemical Elements |last2=Schonfeld, Fred W. |publisher=Reinhold Book Corporation |year=1968 |editor-last=Clifford A. Hampel |location=New York (NY) |pages=[https://archive.org/details/encyclopediaofch00hamp/page/540 540–546] |chapter=Plutonium |lccn=68029938 |ref=CITEREFMiner1968 |chapter-url=https://archive.org/details/encyclopediaofch00hamp |chapter-url-access=registration}}

{{Navbox element isotopes}}
{{Isotopes of plutonium}}
{{Authority control}}

[[Category:Isotopes of plutonium| ]]
[[Category:Plutonium]]
[[Category:Lists of isotopes by element|Plutonium]]