{{Short description|none}} {{Infobox uranium isotopes}} Uranium ({{sub|92}}U) is a naturally occurring radioactive element (radioelement) with no stable isotopes. It has two primordial isotopes, uranium-238 and uranium-235, that have long half-lives and are found in appreciable quantity in Earth's crust. The decay product uranium-234 is also found. Other isotopes such as uranium-233 have been produced in breeder reactors. In addition to isotopes found in nature or nuclear reactors, many isotopes with far shorter half-lives have been produced, ranging from {{sup|214}}U to {{sup|242}}U (except for {{sup|220}}U). The standard atomic weight of natural uranium is {{val|238.02891|(3)}}.
Natural uranium consists of three main isotopes, {{sup|238}}U (99.2739–99.2752% natural abundance), {{sup|235}}U (0.7198–0.7202%), and {{sup|234}}U (0.0050–0.0059%).<ref>{{cite web | title = Uranium Isotopes | url = https://www.globalsecurity.org/wmd/intro/u-isotopes.htm |publisher=GlobalSecurity.org | access-date = 14 March 2012}}</ref> All three isotopes are radioactive (i.e., they are radioisotopes), and the most abundant and stable is uranium-238, with a half-life of {{val|4.463e9|u=years}} (about the age of the Earth).
Uranium-238 is an alpha emitter, decaying through the 18-member uranium series into lead-206. The decay series of uranium-235 (historically called actino-uranium) has 15 members and ends in lead-207. The constant rates of decay in these series makes comparison of the ratios of parent-to-daughter elements useful in radiometric dating. Uranium-233 is made from thorium-232 by neutron bombardment.
Uranium-235 is important for both nuclear reactors (energy production) and nuclear weapons because it is the only isotope existing in nature to any appreciable extent that is fissile in response to thermal neutrons, i.e., thermal neutron capture has a high probability of inducing fission. A chain reaction can be sustained with a large enough (critical) mass of uranium-235. Uranium-238 is also important because it is fertile: it absorbs neutrons to produce a radioactive isotope that decays into plutonium-239, which also is fissile.
==List of isotopes== {{Anchor|Uranium-220|Uranium-243}}
<!--Please delete anchor(s) from the list above or table below if adding a dedicated isotope section(s).-->
{{Isotopes table | symbol = U | refs = NUBASE2020, AME2020 II, IsotopeFRIB, IsomerFRIB | notes = m, histname, unc(), mass#, exen#, exexn#, spin(), spin#, EC, SF, CD, daughter-st, daughter-nst, discoveryname }} |-id=Uranium-214 | {{sup|214}}U<ref name="214U">{{cite journal|last1=Zhang|first1=Z. Y.|last2=Yang|first2=H. B.|last3=Huang|first3=M. H.|last4=Gan|first4=Z. G.|last5=Yuan|first5=C. X.|last6=Qi|first6=C.|last7=Andreyev|first7=A. N.|last8=Liu|first8=M. L.|last9=Ma|first9=L.|last10=Zhang|first10=M. M.|last11=Tian|first11=Y. L.|last12=Wang|first12=Y. S.|last13=Wang|first13=J. G.|last14=Yang|first14=C. L.|last15=Li|first15=G. S.|last16=Qiang|first16=Y. H.|last17=Yang|first17=W. Q.|last18=Chen|first18=R. F.|last19=Zhang|first19=H. B.|last20=Lu|first20=Z. W.|last21=Xu|first21=X. X.|last22=Duan|first22=L. M.|last23=Yang|first23=H. R.|last24=Huang|first24=W. X.|last25=Liu|first25=Z.|last26=Zhou|first26=X. H.|last27=Zhang|first27=Y. H.|last28=Xu|first28=H. S.|last29=Wang|first29=N.|last30=Zhou|first30=H. B.|last31=Wen|first31=X. J.|last32=Huang|first32=S.|last33=Hua|first33=W.|last34=Zhu|first34=L.|last35=Wang|first35=X.|last36=Mao|first36=Y. C.|last37=He|first37=X. T.|last38=Wang|first38=S. Y.|last39=Xu|first39=W. Z.|last40=Li|first40=H. W.|last41=Ren|first41=Z. Z.|last42=Zhou|first42=S. G.|title=New α-Emitting Isotope {{sup|U}}214 and Abnormal Enhancement of α-Particle Clustering in Lightest Uranium Isotopes|journal=Physical Review Letters|volume=126|issue=15|year=2021|article-number=152502|arxiv=2101.06023|doi=10.1103/PhysRevLett.126.152502|pmid=33929212|bibcode=2021PhRvL.126o2502Z|s2cid=231627674}}</ref> | | style="text-align:right" | 92 | style="text-align:right" | 122 | | style="text-align:center" | [https://www.nndc.bnl.gov/discovery/abstracts/92/214.pdf 2021] | {{val|0.52|0.95|0.21|u=ms}} | α | {{sup|210}}Th | 0+ | | |-id=Uranium-215 | rowspan=2|{{sup|215}}U | rowspan=2| | rowspan=2 style="text-align:right" | 92 | rowspan=2 style="text-align:right" | 123 | rowspan=2|215.026720(11) | rowspan=2 style="text-align:center" | [https://www.nndc.bnl.gov/discovery/abstracts/92/215.pdf 2015] | rowspan=2| {{val|1.4|(9)|ul=ms}} | α | {{sup|211}}Th | rowspan=2|5/2−# | rowspan=2| | rowspan=2| |- | β{{sup|+}}? | {{sup|215}}Pa |-id=Uranium-216 | {{sup|216}}U<ref name="216,218U">{{cite journal |last1=Zhang |first1=M. M. |last2=Tian |first2=Y. L. |last3=Wang |first3=Y. S. |last4=Zhang |first4=Z. Y. |last5=Gan |first5=Z. G. |last6=Yang |first6=H. B. |last7=Huang |first7=M. H. |last8=Ma |first8=L. |last9=Yang |first9=C. L. |last10=Wang |first10=J. G. |last11=Yuan |first11=C. X. |last12=Qi |first12=C. |last13=Andreyev |first13=A. N. |last14=Huang |first14=X. Y. |last15=Xu |first15=S. Y. |last16=Zhao |first16=Z. |last17=Chen |first17=L. X. |last18=Wang |first18=J. Y. |last19=Liu |first19=M. L. |last20=Qiang |first20=Y. H. |last21=Li |first21=G. S. |last22=Yang |first22=W. Q. |last23=Chen |first23=R. F. |last24=Zhang |first24=H. B. |last25=Lu |first25=Z. W. |last26=Xu |first26=X. X. |last27=Duan |first27=L. M. |last28=Yang |first28=H. R. |last29=Huang |first29=W. X. |last30=Liu |first30=Z. |last31=Zhou |first31=X. H. |last32=Zhang |first32=Y. H. |last33=Xu |first33=H. S. |last34=Wang |first34=N. |last35=Zhou |first35=H. B. |last36=Wen |first36=X. J. |last37=Huang |first37=S. |last38=Hua |first38=W. |last39=Zhu |first39=L. |last40=Wang |first40=X. |last41=Mao |first41=Y. C. |last42=He |first42=X. T. |last43=Wang |first43=S. Y. |last44=Xu |first44=W. Z. |last45=Li |first45=H. W. |last46=Niu |first46=Y. F. |last47=Guo |first47=L. |last48=Ren |first48=Z. Z. |last49=Zhou |first49=S. G. |title=Fine structure in the α decay of the 8+ isomer in {{sup|216, 218}}U |journal=Physical Review C |date=4 August 2022 |volume=106 |issue=2 |article-number=024305 |doi=10.1103/PhysRevC.106.024305 |s2cid=251359451 |language=en |issn=2469-9985}}</ref> | | style="text-align:right" | 92 | style="text-align:right" | 124 | 216.024760(30) | style="text-align:center" | [https://www.nndc.bnl.gov/discovery/abstracts/92/216.pdf 2015] | {{val|2.25|0.63|0.40|u=ms}} | α | {{sup|212}}Th | 0+ | | |-id=Uranium-216m | style="text-indent:1em" | {{sup|216m}}U | | colspan="3" style="text-indent:2em" | {{val|2206|ul=keV}} | style="text-align:center" | [https://www.nndc.bnl.gov/discovery/isomers/abstracts/92/216U-1.pdf 2015] | {{val|0.89|0.24|0.16|u=ms}} | α | {{sup|212}}Th | 8+ | | |-id=Uranium-217 | rowspan=2|{{sup|217}}U<ref>{{cite journal |last1=Gan |first1=ZaiGuo |last2=Jiang |first2=Jian |last3=Yang |first3=HuaBin |last4=Zhang |first4=ZhiYuan |last5=Ma |first5=Long |last6=Yu |first6=Lin |last7=Wang |first7=JianGuo |last8=Tian |first8=YuLin |last9=Ding |first9=Bing |last10=Huang |first10=TianHeng |last11=Wang |first11=YongSheng |last12=Guo |first12=Song |last13=Sun |first13=MingDao |last14=Wang |first14=KaiLong |last15=Zhou |first15=ShanGui |last16=Ren |first16=ZhongZhou |last17=Zhou |first17=XiaoHong |last18=Xu |first18=HuShan |title=α decay studies of the neutron-deficient uranium isotopes 215-217U |journal=Chinese Science Bulletin |date=1 August 2016 |volume=61 |issue=22 |pages=2502–2511 |doi=10.1360/N972015-01316 |url=https://www.researchgate.net/publication/312030836 |access-date=24 June 2023|doi-access=free }}</ref> | rowspan=2| | rowspan=2 style="text-align:right" | 92 | rowspan=2 style="text-align:right" | 125 | rowspan=2|217.024660(86)# | rowspan=2 style="text-align:center" | [https://www.nndc.bnl.gov/discovery/abstracts/92/217.pdf 2000] | rowspan=2|{{val|19.3|13.3|5.6|u=ms}} | α | {{sup|213}}Th | rowspan=2|(1/2−) | rowspan=2| | rowspan=2| |- | β{{sup|+}}? | {{sup|217}}Pa |-id=Uranium-218 | {{sup|218}}U<ref name="216,218U"/> | | style="text-align:right" | 92 | style="text-align:right" | 126 | 218.023505(15) | style="text-align:center" | [https://www.nndc.bnl.gov/discovery/abstracts/92/218.pdf 1992] | {{val|650|80|70|u=μs}} | α | {{sup|214}}Th | 0+ | | |-id=Uranium-218m | rowspan=2 style="text-indent:1em" | {{sup|218m}}U | rowspan=2| | rowspan=2 colspan="3" style="text-indent:2em" | {{val|2117|ul=keV}} | rowspan=2 style="text-align:center" | [https://www.nndc.bnl.gov/discovery/isomers/abstracts/92/218U-1.pdf 2007] | rowspan=2|{{val|390|60|50|u=μs}} | α | {{sup|214}}Th | rowspan=2|8+ | rowspan=2| | rowspan=2| |- | IT? | {{sup|218}}U |-id=Uranium-219 | rowspan=2|{{sup|219}}U | rowspan=2| | rowspan=2 style="text-align:right" | 92 | rowspan=2 style="text-align:right" | 127 | rowspan=2|219.025009(14) | rowspan=2 style="text-align:center" | [https://www.nndc.bnl.gov/discovery/abstracts/92/219.pdf 1993] | rowspan=2| {{val|60|(7)|ul=μs}} | α | {{sup|215}}Th | rowspan=2|(9/2+) | rowspan=2| | rowspan=2| |- | β{{sup|+}}? | {{sup|219}}Pa |-id=Uranium-221 | rowspan=2|{{sup|221}}U | rowspan=2| | rowspan=2 style="text-align:right" | 92 | rowspan=2 style="text-align:right" | 129 | rowspan=2|221.026323(77) | rowspan=2 style="text-align:center" | [https://www.nndc.bnl.gov/discovery/abstracts/92/221.pdf 2015] | rowspan=2| {{val|0.66|(14)|ul=μs}} | α | {{sup|217}}Th | rowspan=2|(9/2+) | rowspan=2| | rowspan=2| |- | β{{sup|+}}? | {{sup|221}}Pa |-id=Uranium-222 | rowspan=2|{{sup|222}}U | rowspan=2| | rowspan=2 style="text-align:right" | 92 | rowspan=2 style="text-align:right" | 130 | rowspan=2|222.026058(56) | rowspan=2 style="text-align:center" | [https://www.nndc.bnl.gov/discovery/abstracts/92/222.pdf 1983] | rowspan=2| {{val|4.7|(7)|ul=μs}} | α | {{sup|218}}Th | rowspan=2|0+ | rowspan=2| | rowspan=2| |- | β{{sup|+}}? | {{sup|222}}Pa |-id=Uranium-223 | rowspan=2|{{sup|223}}U | rowspan=2| | rowspan=2 style="text-align:right" | 92 | rowspan=2 style="text-align:right" | 131 | rowspan=2|223.027961(63) | rowspan=2 style="text-align:center" | [https://www.nndc.bnl.gov/discovery/abstracts/92/223.pdf 1991] | rowspan=2| {{val|65|(12)|ul=μs}} | α | {{sup|219}}Th | rowspan=2|7/2+# | rowspan=2| | rowspan=2| |- | β{{sup|+}}? | {{sup|223}}Pa |-id=Uranium-224 | rowspan=2|{{sup|224}}U | rowspan=2| | rowspan=2 style="text-align:right" | 92 | rowspan=2 style="text-align:right" | 132 | rowspan=2|224.027636(16) | rowspan=2 style="text-align:center" | [https://www.nndc.bnl.gov/discovery/abstracts/92/224.pdf 1991] | rowspan=2| {{val|396|(17)|ul=μs}} | α | {{sup|220}}Th | rowspan=2|0+ | rowspan=2| | rowspan=2| |- | β{{sup|+}}? | {{sup|224}}Pa |-id=Uranium-225 | {{sup|225}}U | | style="text-align:right" | 92 | style="text-align:right" | 133 | 225.029385(11) | style="text-align:center" | [https://www.nndc.bnl.gov/discovery/abstracts/92/225.pdf 1989] | {{val|62|(4)|ul=ms}} | α | {{sup|221}}Th | 5/2+# | | |-id=Uranium-226 | {{sup|226}}U | | style="text-align:right" | 92 | style="text-align:right" | 134 | 226.029339(12) | style="text-align:center" | [https://www.nndc.bnl.gov/discovery/abstracts/92/226.pdf 1973] | {{val|269|(6)|ul=ms}} | α | {{sup|222}}Th | 0+ | | |-id=Uranium-227 | rowspan=2|{{sup|227}}U | rowspan=2| | rowspan=2 style="text-align:right" | 92 | rowspan=2 style="text-align:right" | 135 | rowspan=2|227.0311811(91) | rowspan=2 style="text-align:center" | [https://www.nndc.bnl.gov/discovery/abstracts/92/227.pdf 1952] | rowspan=2| {{val|1.1|(1)|ul=min}} | α | {{sup|223}}Th | rowspan=2|(3/2+) | rowspan=2| | rowspan=2| |- | β{{sup|+}}? | {{sup|227}}Pa |-id=Uranium-228 | rowspan=2|{{sup|228}}U | rowspan=2| | rowspan=2 style="text-align:right" | 92 | rowspan=2 style="text-align:right" | 136 | rowspan=2|228.031369(14) | rowspan=2 style="text-align:center" | [https://www.nndc.bnl.gov/discovery/abstracts/92/228.pdf 1949] | rowspan=2| {{val|9.1|(2)|ul=min}} | α (97.5%) | {{sup|224}}Th | rowspan=2|0+ | rowspan=2| | rowspan=2| |- | EC (2.5%) | {{sup|228}}Pa |-id=Uranium-229 | rowspan=2|{{sup|229}}U | rowspan=2| | rowspan=2 style="text-align:right" | 92 | rowspan=2 style="text-align:right" | 137 | rowspan=2|229.0335060(64) | rowspan=2 style="text-align:center" | [https://www.nndc.bnl.gov/discovery/abstracts/92/229.pdf 1949] | rowspan=2| {{val|57.8|(5)|ul=min}} | β{{sup|+}} (80%) | {{sup|229}}Pa | rowspan=2|(3/2+) | rowspan=2| | rowspan=2| |- | α (20%) | {{sup|225}}Th |-id=Uranium-230 | rowspan=3|{{sup|230}}U | rowspan=3| | rowspan=3 style="text-align:right" | 92 | rowspan=3 style="text-align:right" | 138 | rowspan=3|230.0339401(48) | rowspan=3 style="text-align:center" | [https://www.nndc.bnl.gov/discovery/abstracts/92/230.pdf 1948] | rowspan=3| {{val|20.23|(2)|ul=d}} | α | {{sup|226}}Th | rowspan=3|0+ | rowspan=3| | rowspan=3| |- | SF ? | (various) |- | CD (4.8×10{{sup|−12}}%) | '''{{sup|208}}Pb'''<br/>'''{{sup|22}}Ne''' |-id=Uranium-231 | rowspan=2|{{sup|231}}U | rowspan=2| | rowspan=2 style="text-align:right" | 92 | rowspan=2 style="text-align:right" | 139 | rowspan=2|231.0362922(29) | rowspan=2 style="text-align:center" | [https://www.nndc.bnl.gov/discovery/abstracts/92/231.pdf 1949] | rowspan=2| {{val|4.2|(1)|ul=d}} | EC | {{sup|231}}Pa | rowspan=2|5/2+# | rowspan=2| | rowspan=2| |- | α (.004%) | {{sup|227}}Th |-id=Uranium-232 | rowspan=4|{{sup|232}}U | rowspan=4| | rowspan=4 style="text-align:right" | 92 | rowspan=4 style="text-align:right" | 140 | rowspan=4|232.0371548(19) | rowspan=4 style="text-align:center" | [https://www.nndc.bnl.gov/discovery/abstracts/92/232.pdf 1949] | rowspan=4| {{val|68.9|(4)|ul=y}} | α | {{sup|228}}Th | rowspan=4|0+ | rowspan=4| | rowspan=4| |- | CD (8.9×10{{sup|−10}}%) | '''{{sup|208}}Pb'''<br/>{{sup|24}}Ne |- | SF (2.7x10{{sup|−12}}%) | (various) |- | CD ? | '''{{sup|204}}Hg'''<br/>{{sup|28}}Mg |-id=Uranium-233 | rowspan=4|{{sup|233}}U | rowspan=4| | rowspan=4 style="text-align:right" | 92 | rowspan=4 style="text-align:right" | 141 | rowspan=4|233.0396343(24) | rowspan=4 style="text-align:center" | [https://www.nndc.bnl.gov/discovery/abstracts/92/233.pdf 1947] | rowspan=4| {{val|1.5919|(15)||e=5|ul=y}} | α | {{sup|229}}Th | rowspan=4|5/2+ | rowspan=4|Trace<ref group=n>Intermediate decay product of {{sup|237}}Np</ref> | rowspan=4| |- | CD (7.2×10{{sup|−11}}%) | {{sup|209}}Pb<br/>{{sup|24}}Ne |- | SF ? | (various) |- | CD ? | {{sup|205}}Hg<br/>{{sup|28}}Mg |-id=Uranium-234m | rowspan=4|{{sup|234}}U<ref group="n">Used in uranium–thorium dating</ref><ref group="n" name="uu">Used in uranium–uranium dating</ref> | rowspan=4|Uranium II | rowspan=4 style="text-align:right" | 92 | rowspan=4 style="text-align:right" | 142 | rowspan=4|234.0409503(12) | rowspan=4 style="text-align:center" | [https://www.nndc.bnl.gov/discovery/abstracts/92/234.pdf 1912] | rowspan=4| {{val|2.455|(6)||e=5|ul=y}} | α | {{sup|230}}Th | rowspan=4|0+ | rowspan=4|[0.000054(5)]<ref group="n">Intermediate decay product of {{sup|238}}U</ref> | rowspan=4|0.000050–<br/>0.000059 |- | SF (1.64×10{{sup|−9}}%) | (various) |- | CD (1.4×10{{sup|−11}}%) | {{sup|206}}Hg<br/>{{sup|28}}Mg |- | CD (9×10{{sup|−12}}%) | {{sup|210,'''208'''}}Pb<br/>{{sup|24,26}}Ne |-id=Uranium-234m | style="text-indent:1em" | {{sup|234m}}U | | colspan="3" style="text-indent:2em" | {{val|1421.257|(17)|ul=keV}} | style="text-align:center" | [https://www.nndc.bnl.gov/discovery/isomers/abstracts/92/234U-1.pdf 1962] | {{val|33.5|(20)|ul=ms}} | IT | {{sup|234}}U | 6− | | |-id=Uranium-235 | rowspan=4|{{sup|235}}U<ref group="n" name="pn">Primordial radionuclide</ref><ref group="n" name="ul">Used in Uranium–lead dating</ref><ref group="n">Important in nuclear reactors</ref> | rowspan=4|Actino-Uranium<br/>Actin-Uranium | rowspan=4 style="text-align:right" | 92 | rowspan=4 style="text-align:right" | 143 | rowspan=4|235.0439281(12) | rowspan=4 style="text-align:center" | [https://www.nndc.bnl.gov/discovery/abstracts/92/235.pdf 1935] | rowspan=4| {{val|7.04|(1)||e=8|ul=y}} | α | {{sup|231}}Th | rowspan=4|7/2− | rowspan=4|[0.007204(6)] | rowspan=4|0.007198–<br/>0.007207 |- | SF (7×10{{sup|−9}}%) | (various) |- | CD (8×10{{sup|−10}}%)<ref name="CD"> {{cite journal |last1=Bonetti |first1=R. |last2=Guglielmetti |first2=A. |year=2007 |title=Cluster radioactivity: an overview after twenty years |url=http://www.rrp.infim.ro/2007_59_2/10_bonetti.pdf |archive-url=https://web.archive.org/web/20160919014152/http://www.rrp.infim.ro/2007_59_2/10_bonetti.pdf |archive-date=19 September 2016 |journal=Romanian Reports in Physics |volume=59 |pages=301–310 }}</ref> | {{sup|211,210}}Pb<br/>{{sup|24,25}}Ne |- | CD (<1.8×10{{sup|−10}}%)<ref name="CD" /> | {{sup|207,206}}Hg<br/>{{sup|28,29}}Mg |-id=Uranium-235m1 | style="text-indent:1em" | {{sup|235m1}}U | | colspan="3" style="text-indent:2em" | {{val|0.076737|(18)|ul=keV}} | style="text-align:center" | [https://www.nndc.bnl.gov/discovery/isomers/abstracts/92/235U-1.pdf 1957] | {{val|25.7|(1)|ul=min}} | IT | '''''{{sup|235}}U''''' | 1/2+ | | |-id=Uranium-235m2 | style="text-indent:1em" | {{sup|235m2}}U | | colspan="3" style="text-indent:2em" | {{val|2500|(300)|ul=keV}} | style="text-align:center" | [https://www.nndc.bnl.gov/discovery/isomers/abstracts/92/235U-2.pdf 2007] | {{val|3.6|(18)|ul=ms}} | SF | (various) | | | |-id=Uranium-236 | rowspan=3|{{sup|236}}U | rowspan=3|Thoruranium<ref name="thoruranium">{{cite journal |last1=Trenn |first1=Thaddeus J. |date=1978 |title=Thoruranium (U-236) as the extinct natural parent of thorium: The premature falsification of an essentially correct theory |journal=Annals of Science |volume=35 |issue=6 |pages=581–97 |doi=10.1080/00033797800200441}}</ref> | rowspan=3 style="text-align:right" | 92 | rowspan=3 style="text-align:right" | 144 | rowspan=3|236.0455661(12) | rowspan=3 style="text-align:center" | [https://www.nndc.bnl.gov/discovery/abstracts/92/236.pdf 1951] | rowspan=3| {{val|2.342|(4)||e=7|ul=y}} | α | '''''{{sup|232}}Th''''' | rowspan=3|0+ | rowspan=3|10<sup>−11</sup> to 10<sup>−10</sup><ref>[https://doi.org/10.1016/j.nimb.2008.03.002 Natural and anthropogenic 236U ...] uranium and uranium ore samples</ref><ref group=n>Intermediate decay product of {{sup|244}}Pu, also produced by neutron capture of {{sup|235}}U</ref> | rowspan=3| |- | SF (9.6×10{{sup|−8}}%) | (various) |- | CD (2.0×10{{sup|−11}}%)<ref name="CD" /> | {{sup|208,206}}Hg<br/>{{sup|28,30}}Mg |-id=Uranium-236m1 | style="text-indent:1em" | {{sup|236m1}}U | | colspan="3" style="text-indent:2em" | {{val|1052.5|(6)|ul=keV}} | style="text-align:center" | [https://www.nndc.bnl.gov/discovery/isomers/abstracts/92/236U-2.pdf 1973] | {{val|100|(4)|ul=ns}} | IT | {{sup|236}}U | 4− | | |-id=Uranium-236m2 | rowspan=2 style="text-indent:1em" | {{sup|236m2}}U | rowspan=2| | rowspan=2 colspan="3" style="text-indent:2em" | {{val|2750|(3)|ul=keV}} | rowspan=2 style="text-align:center" | [https://www.nndc.bnl.gov/discovery/isomers/abstracts/92/236U-1.pdf 1969] | rowspan=2| {{val|120|(2)|ul=ns}} | IT (87%) | {{sup|236}}U | rowspan=2|(0+) | rowspan=2| | rowspan=2| |- | SF (13%) | (various) |-id=Uranium-237m | {{sup|237}}U | | style="text-align:right" | 92 | style="text-align:right" | 145 | 237.0487283(13) | style="text-align:center" | [https://www.nndc.bnl.gov/discovery/abstracts/92/237.pdf 1940] | {{val|6.752|(2)|ul=d}} | β{{sup|−}} | {{sup|237}}Np | 1/2+ | Trace<ref group=n>Neutron capture product, parent of trace quantities of {{sup|237}}Np</ref> | |-id=Uranium-237m | style="text-indent:1em" | {{sup|237m}}U | | colspan="3" style="text-indent:2em" | {{val|274.0|(10)|ul=keV}} | style="text-align:center" | [https://www.nndc.bnl.gov/discovery/isomers/abstracts/92/237U-1.pdf 1968] | {{val|155|(6)|ul=ns}} | IT | {{sup|237}}U | 7/2− | | |-id=Uranium-238 | rowspan=3|{{sup|238}}U<ref group="n" name="uu" /><ref group="n" name="pn" /><ref group="n" name="ul" /> | rowspan=3|Uranium I | rowspan=3 style="text-align:right" | 92 | rowspan=3 style="text-align:right" | 146 | rowspan=3|238.050787618(15)<ref>{{cite journal | last1=Kromer | first1=Kathrin | last2=Lyu | first2=Chunhai | last3=Bieroń | first3=Jacek | last4=Door | first4=Menno | last5=Enzmann | first5=Lucia | last6=Filianin | first6=Pavel | last7=Gaigalas | first7=Gediminas | last8=Harman | first8=Zoltán | last9=Herkenhoff | first9=Jost | last10=Huang | first10=Wenjia | last11=Keitel | first11=Christoph H. | last12=Eliseev | first12=Sergey | last13=Blaum | first13=Klaus | title=Atomic mass determination of uranium-238 | journal=Physical Review C | publisher=American Physical Society (APS) | volume=109 | issue=2 | date=2024-02-06 | article-number=L021301 | issn=2469-9985 | doi=10.1103/physrevc.109.l021301| arxiv=2312.17041 | bibcode=2024PhRvC.109b1301K }}</ref> | rowspan=3 style="text-align:center" | [https://www.nndc.bnl.gov/discovery/abstracts/92/238.pdf 1896] | rowspan=3| {{val|4.463|(3)||e=9|ul=y}} | α | {{sup|234}}Th | rowspan=3|0+ | rowspan=3|[0.992742(10)] | rowspan=3|0.992739–<br/>0.992752 |- | SF (5.44×10{{sup|−5}}%) | (various) |- | β{{sup|−}}β{{sup|−}} (2.2×10{{sup|−10}}%) | {{sup|238}}Pu |-id=Uranium-238m | rowspan=2 style="text-indent:1em" | {{sup|238m}}U | rowspan=2| | rowspan=2 colspan="3" style="text-indent:2em" | {{val|2557.9|(5)|ul=keV}} | rowspan=2 style="text-align:center" | [https://www.nndc.bnl.gov/discovery/isomers/abstracts/92/238U-1.pdf 1970] | rowspan=2| {{val|280|(6)|ul=ns}} | IT (97.4%) | '''''{{sup|238}}U''''' | rowspan=2|0+ | rowspan=2| | rowspan=2| |- | SF (2.6%) | (various) |-id=Uranium-239 | {{sup|239}}U | | style="text-align:right" | 92 | style="text-align:right" | 147 | 239.0542920(16) | style="text-align:center" | [https://www.nndc.bnl.gov/discovery/abstracts/92/239.pdf 1937] | {{val|23.45|(2)|ul=min}} | β{{sup|−}} | {{sup|239}}Np | 5/2+ | Trace<ref group=n>Neutron capture product; parent of trace quantities of {{sup|239}}Pu</ref> | |-id=Uranium-239m1 | style="text-indent:1em" | {{sup|239m1}}U | | colspan="3" style="text-indent:2em" | {{val|133.7991|(10)|ul=keV}} | style="text-align:center" | [https://www.nndc.bnl.gov/discovery/isomers/abstracts/92/239U-1.pdf 1975] | {{val|780|(40)|ul=ns}} | IT | {{sup|239}}U | 1/2+ | | |-id=Uranium-239m2 | rowspan=2 style="text-indent:1em" | {{sup|239m2}}U | rowspan=2| | rowspan=2 colspan="3" style="text-indent:2em" | {{val|2500|(900)|ul=keV}} | rowspan=2 style="text-align:center" | [https://www.nndc.bnl.gov/discovery/isomers/abstracts/92/239U-2.pdf 1994] | rowspan=2| {{val|250|ul=ns|p=>}} | SF? | (various) | rowspan=2|0+ | rowspan=2| | rowspan=2| |- | IT? | {{sup|239}}U |-id=Uranium-240 | rowspan=2|{{sup|240}}U | rowspan=2| | rowspan=2 style="text-align:right" | 92 | rowspan=2 style="text-align:right" | 148 | rowspan=2|240.0565924(27) | rowspan=2 style="text-align:center" | [https://www.nndc.bnl.gov/discovery/abstracts/92/240.pdf 1953] | rowspan=2| {{val|14.1|(1)|ul=h}} | β{{sup|−}} | {{sup|240m}}Np<ref>ENSDF analysis available at {{NNDC}}</ref> | rowspan=2|0+ | rowspan=2|Trace<ref group=n>Intermediate decay product of {{sup|244}}Pu</ref> | rowspan=2| |- | α? | {{sup|236}}Th |-id=Uranium-241 | {{sup|241}}U<ref name=U241>{{cite journal |title = Discovery of New Isotope {{sup|241}}U and Systematic High-Precision Atomic Mass Measurements of Neutron-Rich Pa-Pu Nuclei Produced via Multinucleon Transfer Reactions |author1= Niwase, T. |author2=Watanabe, Y. X. |author3=Hirayama, Y. |author4=Mukai, M. |author5=Schury, P. |author6=Andreyev, A. N. |author7=Hashimoto, T. |author8=Iimura, S. |author9=Ishiyama, H. |author10=Ito, Y. |author11=Jeong, S. C. |author12=Kaji, D. |author13=Kimura, S. |author14=Miyatake, H. |author15=Morimoto, K. |author16=Moon, J.-Y. |author17=Oyaizu, M. |author18=Rosenbusch, M. |author19=Taniguchi, A. |author20=Wada, M. |display-authors=3 |journal = Physical Review Letters |volume = 130 |issue = 13 |pages = 132502-1–132502-6 |year = 2023 |doi = 10.1103/PhysRevLett.130.132502|pmid= 37067317 |s2cid= 257976576 |url= https://eprints.whiterose.ac.uk/197980/1/PhysRevLett.130.132502.pdf |bibcode=2023PhRvL.130m2502N }}</ref> | | style="text-align:right" | 92 | style="text-align:right" | 149 | 241.06031(5)<!--WP:CALC (unit conversion and error propagation) from the Dalton mass and the mass excess in the paper--><ref name="U241"/> | style="text-align:center" | [https://www.nndc.bnl.gov/discovery/abstracts/92/241.pdf 2023] | {{val|40|ul=min|end=#}}<ref name="u241">{{Cite news |last=Mukunth |first=Vasudevan |date=2023-04-05 |title=In pursuit of a 'magic number', physicists discover new uranium isotope |language=en-IN |work=The Hindu |url=https://www.thehindu.com/sci-tech/science/in-pursuit-of-a-magic-number-physicists-discover-new-uranium-isotope/article66699249.ece |access-date=2023-04-12 |issn=0971-751X}}</ref><ref>{{Cite news |last=Yirka |first=Bob |date=April 5, 2023 |title=Previously unknown isotope of uranium discovered |language=en |work=Phys.org |url=https://phys.org/news/2023-04-previously-unknown-isotope-uranium.html |access-date=2023-04-12}}</ref> | β{{sup|−}} | {{sup|241}}Np | 7/2+# | |--> |-id=Uranium-242 | {{sup|242}}U | | style="text-align:right" | 92 | style="text-align:right" | 150 | 242.06296(10)<!--WP:CALC (unit conversion and error propagation) from the Dalton mass and the mass excess in the paper--><ref name="U241"/> | style="text-align:center" | [https://www.nndc.bnl.gov/discovery/abstracts/92/242.pdf 1979] | {{val|16.8|(5)|ul=min}} | β{{sup|−}} | {{sup|242}}Np | 0+ | | {{Isotopes table/footer}}
==Actinides vs fission products== {{Actinidesvsfissionproducts}} {{Clear}}
==Uranium-232== {{main|Uranium-232}}
Uranium-232 has a half-life of 68.9 years and is a side product in the thorium cycle. It has been cited as an obstacle to nuclear proliferation using {{sup|233}}U, because the intense gamma radiation from {{sup|208}}Tl (a daughter of {{sup|232}}U, produced relatively quickly) makes {{sup|233}}U contaminated with it more difficult to handle. Uranium-232 is a rare example of an even-even isotope that is fissile with both thermal and fast neutrons.<ref>{{cite web |url=https://www.nuclear-power.net/nuclear-power-plant/nuclear-fuel/uranium/uranium-232/ |title=Uranium 232 |publisher=Nuclear Power |access-date=3 June 2019 |url-status=live |archive-url=https://web.archive.org/web/20190226212021/https://www.nuclear-power.net/nuclear-power-plant/nuclear-fuel/uranium/uranium-232/ |archive-date=26 February 2019}}</ref><ref>{{cite web |url=http://atom.kaeri.re.kr/nuchart/getEvaf.jsp?mat=9219&lib=endfb7.1 |title=INCIDENT NEUTRON DATA |date=2011-12-14 |website=atom.kaeri.re.kr}}</ref>
==Uranium-233== {{Main|Uranium-233}}
Uranium-233 is a fissile isotope that is bred from thorium-232 as part of the thorium fuel cycle. {{sup|233}}U was investigated for use in nuclear weapons and as a reactor fuel. It was occasionally tested but never deployed in nuclear weapons and has not been used commercially as a nuclear fuel.<ref name="Forsburg">{{cite journal|author1=C. W. Forsburg|author2=L. C. Lewis|title=Uses For Uranium-233: What Should Be Kept for Future Needs?|publisher=Oak Ridge National Laboratory|journal=Ornl-6952|date=1999-09-24|url=https://moltensalt.org/references/static/downloads/pdf/ORNL-6952.pdf}}</ref> It has been used successfully in experimental nuclear reactors and has been proposed for much wider use as a nuclear fuel. It has a half-life of around 160,000 years.
Uranium-233 is produced by neutron irradiation of thorium-232. When thorium-232 absorbs a neutron, it becomes thorium-233, which has a half-life of only 22 minutes. Thorium-233 beta decays into protactinium-233. Protactinium-233 has a half-life of 27 days and beta decays into uranium-233; some proposed molten salt reactor designs attempt to physically isolate the protactinium from further neutron capture before beta decay can occur.
Uranium-233 usually fissions on neutron absorption but sometimes retains the neutron, becoming uranium-234. The capture-to-fission ratio is smaller than the other two major fissile fuels, uranium-235 and plutonium-239; it is also lower than that of short-lived plutonium-241, but bested by very difficult-to-produce neptunium-236.
==Uranium-234== {{Main|Uranium-234}}
{{sup|234}}U occurs in natural uranium as an indirect decay product of uranium-238, but makes up only 55 parts per million of the uranium because its half-life of 245,500 years is only about 1/18,000 that of {{sup|238}}U. The path of production of {{sup|234}}U is this: {{sup|238}}U alpha decays to thorium-234. Next, with a short half-life, {{sup|234}}Th beta decays to protactinium-234. Finally, {{sup|234}}Pa beta decays to {{sup|234}}U.{{NUBASE2016|ref}}<ref name="HCWR212" />
{{sup|234}}U alpha decays to thorium-230, except for a small percentage of nuclei that undergo spontaneous fission.
Extraction of small amounts of {{sup|234}}U from natural uranium could be done using isotope separation, similar to normal uranium-enrichment. However, there is no real demand in chemistry, physics, or engineering for isolating {{sup|234}}U. Very small pure samples of {{sup|234}}U can be extracted via the chemical ion-exchange process, from samples of plutonium-238 that have aged somewhat to allow some alpha decay to {{sup|234}}U.
Enriched uranium contains more {{sup|234}}U than natural uranium as a byproduct of the uranium enrichment process aimed at obtaining uranium-235, which concentrates lighter isotopes even more strongly than it does {{sup|235}}U. The increased percentage of {{sup|234}}U in enriched natural uranium is acceptable in current nuclear reactors, but (re-enriched) reprocessed uranium might contain even higher fractions of {{sup|234}}U, which is undesirable.<ref name="RpU">{{cite conference |publisher=International Atomic Energy Agency |date=2009 |isbn=978-92-0-157109-0 |issn=1684-2073 |location=Vienna |title=Use of Reprocessed Uranium |journal=Technical Document |url=https://www-pub.iaea.org/MTCD/publications/PDF/TE_1630_CD/PDF/IAEA-TECDOC-1630.pdf}}</ref> This is because {{sup|234}}U is not fissile, though it is fertile. It tends to absorb slow neutrons in a nuclear reactor, becoming fissile {{sup|235}}U.<ref name="HCWR212">{{cite book |editor-last=Ronen |editor-first=Y. |publisher=CRC Press |title=High converting water reactors |year=1990 |isbn=0-8493-6081-1 |lccn=89-25332 |page=212}}</ref><ref name="RpU" />
{{sup|234}}U has a neutron capture cross section of about 100 barns for thermal neutrons, and about 700 barns for its resonance integral—the average over neutrons having various intermediate energies. In a nuclear reactor, non-fissile isotopes capture a neutron breeding fissile isotopes. {{sup|234}}U is converted to {{sup|235}}U more easily and therefore at a greater rate than uranium-238 is to plutonium-239 (via neptunium-239), because {{sup|238}}U has a much smaller neutron-capture cross section of just 2.7 barns.
==Uranium-235== {{Main|Uranium-235}}
Uranium-235 makes up about 0.72% of natural uranium. Unlike the predominant isotope uranium-238, it is fissile, i.e., it can sustain a fission chain reaction. It is the only fissile isotope that is a primordial nuclide or found in significant quantity in nature.
Uranium-235 has a half-life of 704 million years. It was discovered in 1935 by Arthur Jeffrey Dempster. Its fission cross section for slow thermal neutrons is about {{val|584.3|1}} barns.<ref name="StandardReactionIAEA">{{cite web |title=#Standard Reaction: 235U(n,f) |url=https://www-nds.iaea.org/standards/Data/standards-235U_xs-data.txt |website=www-nds.iaea.org |publisher=IAEA |access-date=4 May 2020}}</ref> For fast neutrons it is on the order of 1 barn. At thermal energy levels, about 5 of 6 neutron absorptions result in fission and 1 of 6 result in neutron capture forming uranium-236.<ref>{{cite journal|author1=B. C. Diven |author2=J. Terrell |author3=A. Hemmendinger|title=Capture-to-Fission Ratios for Fast Neutrons in U235|journal=Physical Review Letters|date=1 January 1958|doi=10.1103/PhysRev.109.144|volume=109|issue=1 |pages=144–150|bibcode=1958PhRv..109..144D}}</ref> The fission-to-capture ratio improves for faster neutrons.
==Uranium-236== {{Main|Uranium-236}}
'''Uranium-236''' has a half-life of about 23 million years; and is neither fissile with thermal neutrons, nor very good fertile material, but is generally considered a nuisance and long-lived radioactive waste. It is found in spent nuclear fuel and in the reprocessed uranium made from spent nuclear fuel.
==Uranium-237== <!-- {{Main|Uranium-237}} -->'''Uranium-237''' has a half-life of about 6.75 days. It decays into neptunium-237 by beta decay. It was discovered by Japanese physicist Yoshio Nishina in 1940, who in a near-miss discovery, inferred the creation of element 93, but was unable to isolate the then-unknown element or measure its decay properties.<ref>{{Cite journal |last=Ikeda |first=Nagao |date=July 25, 2011 |title=The discoveries of uranium 237 and symmetric fission — From the archival papers of Nishina and Kimura |journal=Proceedings of the Japan Academy. Series B, Physical and Biological Sciences |volume=87 |issue=7 |pages=371–376 |doi=10.2183/pjab.87.371 |pmid=21785255 |pmc=3171289 |bibcode=2011PJAB...87..371I }}</ref>
==Uranium-238== {{Main|Uranium-238}}
Uranium-238 ({{sup|238}}U or U-238) is the most common isotope of uranium in nature. It is not fissile, but is fertile: <ref>{{cite web|url=https://www.iaea.org/sites/default/files/gc/gc50inf-3-att6_en.pdf|title=The Front End of the Uranium Fuel Cycle|publisher=iaea.org|quote=The nucleus of the more abundant isotope 238U, when stuck by a neutron will absorb the neutron and become uranium-239 (239U), which undergoes two consecutive ß- decays to yield plutonium-239 (239Pu), which, like 235U, is also a fissile isotope. The 238U is therefore termed a ‘fertile isotope’. }}</ref> it can capture a slow neutron and after two beta decays become fissile plutonium-239. Uranium-238 is fissionable by fast neutrons, but cannot support a chain reaction because inelastic scattering reduces neutron energy below the range where fast fission of one or more next-generation nuclei is probable. Doppler broadening of {{sup|238}}U's neutron absorption resonances, increasing absorption as fuel temperature increases, is an essential negative feedback mechanism for reactor control.
About 99.274% of natural uranium is uranium-238, which has a half-life of 4.463×10{{sup|9}} years. Depleted uranium has an even higher concentration of {{sup|238}}U, and even low-enriched uranium (LEU) is still mostly {{sup|238}}U. Reprocessed uranium is also mainly {{sup|238}}U, with about as much uranium-235 as natural uranium, a comparable proportion of uranium-236, and much smaller amounts of other isotopes of uranium such as uranium-234, uranium-233, and uranium-232.
==Uranium-239==
'''Uranium-239''' is usually produced by exposing {{sup|238}}U to neutron radiation in a nuclear reactor. {{sup|239}}U has a half-life of about 23.45 minutes and beta decays into neptunium-239, with a total decay energy of about 1.29 MeV.<ref>''CRC Handbook of Chemistry and Physics'', 57th Ed. p. B-345</ref><!-- assume decay energy 1.28 MeV and max beta energy 1.29 MeV is a transposition error--> The most common gamma decay at 74.660 keV accounts for the difference in the two major channels of beta emission energy, at 1.28 and 1.21 MeV.<ref>''CRC Handbook of Chemistry and Physics'', 57th Ed. p. B-423</ref>
{{sup|239}}Np then, with a half-life of about 2.356 days, beta-decays to plutonium-239.
==References== {{Reflist}}
{{Navbox element isotopes}} {{Authority control}}
Category:Isotopes of uranium Category:Uranium Uranium