Isotopes of uranium

Isotopes of uranium (92U)
Main isotopes[1] Decay
abun­dance half-life (t1/2) mode pro­duct
232U synth 68.9 y α 228Th
SF –
233U trace 1.592×105 y[2] α 229Th
SF –
234U 0.005% 2.455×105 y α 230Th
SF –
235U 0.720% 7.04×108 y α 231Th
SF –
236U trace 2.342×107 y α 232Th
SF –
238U 99.3% 4.468×109 y α 234Th
SF –
β−β− 238Pu
Standard atomic weight Ar°(U)
238.02891(3)[3][4]

Uranium (92U) is a radioactive element. It can be found in nature. It has no stable isotopes. It has 2 primordial isotopes: uranium-238 and uranium-235. They have long half-lives and are found Earth's crust. The decay product uranium-234 is also found. Other isotopes uranium-233 are found breeder reactors. Some of these isotopes are in nature or nuclear reactors. Some isotopes with very short half-lives have been produced. 214U to 242U (except for 220U) have been made. The standard atomic weight of natural uranium is 238.02891(3).

Natural uranium has three isotopes: 238U (99.2739–99.2752% natural abundance), 235U (0.7198–0.7202%), and 234U (0.0050–0.0059%).[5] All of these isotopes are radioactive (they are radioisotopes). The most common and stable isotope is uranium-238. It has a half-life of 4.463×109 years (about the age of the Earth).

Uranium-238 is an alpha emitter. It decays through the uranium series. After decaying, it turns into lead-206. The decay series of uranium-235 ends in lead-207. These isotopes decay at a constant rate. This makes these elements useful in radiometric dating.

Uranium-235 is important in nuclear reactors and nuclear weapons. It is the only common isotope in nature that is fissile from thermal neutrons (meaning: it is the only common isotope that has a high probability of causing fission). Uranium-238 is also important because it is fertile.

List of isotopes


Nuclide
[n 1]		 Historic
name		 Z N Isotopic mass (Da)[6]
[n 2][n 3]		 Half-life[1]
 Decay
mode[1]
[n 4]		 Daughter
isotope
[n 5][n 6]		 Spin and
parity[1]
[n 7][n 8]		 Natural abundance (mole fraction)
Excitation energy[n 8] Normal proportion[1] Range of variation
214U[7] 92 122 2021 0.52+0.95
−0.21 ms		 α 210Th 0+
215U 92 123 215.026720(11) 2015 1.4(9) ms α 211Th 5/2−#
β+? 215Pa
216U[8] 92 124 216.024760(30) 2015 2.25+0.63
−0.40 ms		 α 212Th 0+
216mU 2206 keV 2015 0.89+0.24
−0.16 ms		 α 212Th 8+
217U[9] 92 125 217.024660(86)# 2000 19.3+13.3
−5.6 ms		 α 213Th (1/2−)
β+? 217Pa
218U[8] 92 126 218.023505(15) 1992 650+80
−70 μs		 α 214Th 0+
218mU 2117 keV 2007 390+60
−50 μs		 α 214Th 8+
IT? 218U
219U 92 127 219.025009(14) 1993 60(7) μs α 215Th (9/2+)
β+? 219Pa
221U 92 129 221.026323(77) 2015 0.66(14) μs α 217Th (9/2+)
β+? 221Pa
222U 92 130 222.026058(56) 1983 4.7(7) μs α 218Th 0+
β+? 222Pa
223U 92 131 223.027961(63) 1991 65(12) μs α 219Th 7/2+#
β+? 223Pa
224U 92 132 224.027636(16) 1991 396(17) μs α 220Th 0+
β+? 224Pa
225U 92 133 225.029385(11) 1989 62(4) ms α 221Th 5/2+#
226U 92 134 226.029339(12) 1973 269(6) ms α 222Th 0+
227U 92 135 227.0311811(91) 1952 1.1(1) min α 223Th (3/2+)
β+? 227Pa
228U 92 136 228.031369(14) 1949 9.1(2) min α (97.5%) 224Th 0+
EC (2.5%) 228Pa
229U 92 137 229.0335060(64) 1949 57.8(5) min β+ (80%) 229Pa (3/2+)
α (20%) 225Th
230U 92 138 230.0339401(48) 1948 20.23(2) d α 226Th 0+
SF ? (various)
CD (4.8×10−12%) 208Pb
22Ne
231U 92 139 231.0362922(29) 1949 4.2(1) d EC 231Pa 5/2+#
α (.004%) 227Th
232U 92 140 232.0371548(19) 1949 68.9(4) y α 228Th 0+
CD (8.9×10−10%) 208Pb
24Ne
SF (2.7x10−12%) (various)
CD ? 204Hg
28Mg
233U 92 141 233.0396343(24) 1947 1.5919(15)×105 y α 229Th 5/2+ Trace[n 9]
CD (7.2×10−11%) 209Pb
24Ne
SF ? (various)
CD ? 205Hg
28Mg
234U[n 10][n 11] Uranium II 92 142 234.0409503(12) 1912 2.455(6)×105 y α 230Th 0+ [0.000054(5)][n 12] 0.000050–
0.000059
SF (1.64×10−9%) (various)
CD (1.4×10−11%) 206Hg
28Mg
CD (9×10−12%) 210,208Pb
24,26Ne
234mU 1421.257(17) keV 1962 33.5(20) ms IT 234U 6−
235U[n 13][n 14][n 15] Actino-Uranium
Actin-Uranium		 92 143 235.0439281(12) 1935 7.04(1)×108 y α 231Th 7/2− [0.007204(6)] 0.007198–
0.007207
SF (7×10−9%) (various)
CD (8×10−10%)[10] 211,210Pb
24,25Ne
CD (<1.8×10−10%)[10] 207,206Hg
28,29Mg
235m1U 0.076737(18) keV 1957 25.7(1) min IT 235U 1/2+
235m2U 2500(300) keV 2007 3.6(18) ms SF (various)
236U Thoruranium[11] 92 144 236.0455661(12) 1951 2.342(4)×107 y α 232Th 0+ 10−11 to 10−10[12][n 16]
SF (9.6×10−8%) (various)
CD (2.0×10−11%)[10] 208,206Hg
28,30Mg
236m1U 1052.5(6) keV 1973 100(4) ns IT 236U 4−
236m2U 2750(3) keV 1969 120(2) ns IT (87%) 236U (0+)
SF (13%) (various)
237U 92 145 237.0487283(13) 1940 6.752(2) d β− 237Np 1/2+ Trace[n 17]
237mU 274.0(10) keV 1968 155(6) ns IT 237U 7/2−
238U[n 11][n 13][n 14] Uranium I 92 146 238.050787618(15)[13] 1896 4.463(3)×109 y α 234Th 0+ [0.992742(10)] 0.992739–
0.992752
SF (5.44×10−5%) (various)
β−β− (2.2×10−10%) 238Pu
238mU 2557.9(5) keV 1970 280(6) ns IT (97.4%) 238U 0+
SF (2.6%) (various)
239U 92 147 239.0542920(16) 1937 23.45(2) min β− 239Np 5/2+ Trace[n 18]
239m1U 133.7991(10) keV 1975 780(40) ns IT 239U 1/2+
239m2U 2500(900) keV 1994 >250 ns SF? (various) 0+
IT? 239U
240U 92 148 240.0565924(27) 1953 14.1(1) h β− 240mNp[14] 0+ Trace[n 19]
α? 236Th
241U[15] 92 149 241.06031(5)[15] 2023 40# min[16][17] β− 241Np 7/2+#
242U 92 150 242.06296(10)[15] 1979 16.8(5) min β− 242Np 0+
This table header & footer:
  1. ↑ mU – Excited nuclear isomer.
  2. ↑ ( ) – Uncertainty (1σ) is given in concise form in parentheses after the corresponding last digits.
  3. ↑ # – Atomic mass marked #: value and uncertainty derived not from purely experimental data, but at least partly from trends from the Mass Surface (TMS).
  4. ↑ Modes of decay:
    CD:Cluster decay
    EC:Electron capture
    SF:Spontaneous fission
  5. ↑ Bold italics symbol as daughter – Daughter product is nearly stable.
  6. ↑ Bold symbol as daughter – Daughter product is stable.
  7. ↑ ( ) spin value – Indicates spin with weak assignment arguments.
  8. 1 2 # – Values marked # are not purely derived from experimental data, but at least partly from trends of neighboring nuclides (TNN).
  9. ↑ Intermediate decay product of 237Np
  10. ↑ Used in uranium–thorium dating
  11. 1 2 Used in uranium–uranium dating
  12. ↑ Intermediate decay product of 238U
  13. 1 2 Primordial radionuclide
  14. 1 2 Used in Uranium–lead dating
  15. ↑ Important in nuclear reactors
  16. ↑ Intermediate decay product of 244Pu, also produced by neutron capture of 235U
  17. ↑ Neutron capture product, parent of trace quantities of 237Np
  18. ↑ Neutron capture product; parent of trace quantities of 239Pu
  19. ↑ Intermediate decay product of 244Pu

Actinides vs fission products

Actinides and fission products by half-life
Actinides by decay chain Half-life
range (a)		 Fission products of 235U by yield[18]
4n
(Thorium)		 4n + 1
(Neptunium)		 4n + 2
(Radium)		 4n + 3
(Actinium)		 4.5–7% 0.04–1.25% <0.001%
228Ra№ 4–6 a 155Euþ
248Bk[19] > 9 a
244Cmƒ 241Puƒ 250Cf 227Ac№ 10–29 a 90Sr 85Kr 113mCdþ
232Uƒ 238Puƒ 243Cmƒ 29–97 a 137Cs 151Smþ 121mSn
249Cfƒ 242mAmƒ 141–351 a

No fission products have a half-life
in the range of 100 a–210 ka ...

241Amƒ 251Cfƒ[20] 430–900 a
226Ra№ 247Bk 1.3–1.6 ka
240Pu 229Th 246Cmƒ 243Amƒ 4.7–7.4 ka
245Cmƒ 250Cm 8.3–8.5 ka
239Puƒ 24.1 ka
230Th№ 231Pa№ 32–76 ka
236Npƒ 233Uƒ 234U№ 150–250 ka 99Tc₡ 126Sn
248Cm 242Pu 327–375 ka 79Se₡
1.33 Ma 135Cs₡
237Npƒ 1.61–6.5 Ma 93Zr 107Pd
236U 247Cmƒ 15–24 Ma 129I₡
244Pu 80 Ma

... nor beyond 15.7 Ma[21]

232Th№ 238U№ 235Uƒ№ 0.7–14.1 Ga
  • ₡,  has thermal neutron capture cross section in the range of 8–50 barns
  • ƒ,  fissile
  • №,  primarily a naturally occurring radioactive material (NORM)
  • þ,  neutron poison (thermal neutron capture cross section greater than 3k barns)

References

  1. 1 2 3 4 5 Kondev, F. G.; Wang, M.; Huang, W. J.; Naimi, S.; Audi, G. (2021). "The NUBASE2020 evaluation of nuclear properties" (PDF). Chinese Physics C. 45 (3): 030001. doi:10.1088/1674-1137/abddae.
  2. ↑ Magurno, B.A.; Pearlstein, S, eds. (1981). Proceedings of the conference on nuclear data evaluation methods and procedures. BNL-NCS 51363, vol. II (PDF). Upton, NY (USA): Brookhaven National Lab. pp. 835 ff. Retrieved 2014-08-06.
  3. ↑ "Standard Atomic Weights: Uranium". CIAAW. 1999.
  4. ↑ Prohaska, Thomas; Irrgeher, Johanna; Benefield, Jacqueline; Böhlke, John K.; Chesson, Lesley A.; Coplen, Tyler B.; Ding, Tiping; Dunn, Philip J. H.; Gröning, Manfred; Holden, Norman E.; Meijer, Harro A. J. (2022-05-04). "Standard atomic weights of the elements 2021 (IUPAC Technical Report)". Pure and Applied Chemistry. doi:10.1515/pac-2019-0603. ISSN 1365-3075.
  5. ↑ "Uranium Isotopes". GlobalSecurity.org. Retrieved 14 March 2012.
  6. ↑ Wang, Meng; Huang, W.J.; Kondev, F.G.; Audi, G.; Naimi, S. (2021). "The AME 2020 atomic mass evaluation (II). Tables, graphs and references*". Chinese Physics C. 45 (3): 030003. doi:10.1088/1674-1137/abddaf.
  7. ↑ Zhang, Z. Y.; Yang, H. B.; Huang, M. H.; Gan, Z. G.; Yuan, C. X.; Qi, C.; Andreyev, A. N.; Liu, M. L.; Ma, L.; Zhang, M. M.; Tian, Y. L.; Wang, Y. S.; Wang, J. G.; Yang, C. L.; Li, G. S.; Qiang, Y. H.; Yang, W. Q.; Chen, R. F.; Zhang, H. B.; Lu, Z. W.; Xu, X. X.; Duan, L. M.; Yang, H. R.; Huang, W. X.; Liu, Z.; Zhou, X. H.; Zhang, Y. H.; Xu, H. S.; Wang, N.; Zhou, H. B.; Wen, X. J.; Huang, S.; Hua, W.; Zhu, L.; Wang, X.; Mao, Y. C.; He, X. T.; Wang, S. Y.; Xu, W. Z.; Li, H. W.; Ren, Z. Z.; Zhou, S. G. (2021). "New α-Emitting Isotope U214 and Abnormal Enhancement of α-Particle Clustering in Lightest Uranium Isotopes". Physical Review Letters. 126 (15) 152502. arXiv:2101.06023. Bibcode:2021PhRvL.126o2502Z. doi:10.1103/PhysRevLett.126.152502. PMID 33929212. S2CID 231627674.
  8. 1 2 Zhang, M. M.; Tian, Y. L.; Wang, Y. S.; Zhang, Z. Y.; Gan, Z. G.; Yang, H. B.; Huang, M. H.; Ma, L.; Yang, C. L.; Wang, J. G.; Yuan, C. X.; Qi, C.; Andreyev, A. N.; Huang, X. Y.; Xu, S. Y.; Zhao, Z.; Chen, L. X.; Wang, J. Y.; Liu, M. L.; Qiang, Y. H.; Li, G. S.; Yang, W. Q.; Chen, R. F.; Zhang, H. B.; Lu, Z. W.; Xu, X. X.; Duan, L. M.; Yang, H. R.; Huang, W. X.; Liu, Z.; Zhou, X. H.; Zhang, Y. H.; Xu, H. S.; Wang, N.; Zhou, H. B.; Wen, X. J.; Huang, S.; Hua, W.; Zhu, L.; Wang, X.; Mao, Y. C.; He, X. T.; Wang, S. Y.; Xu, W. Z.; Li, H. W.; Niu, Y. F.; Guo, L.; Ren, Z. Z.; Zhou, S. G. (4 August 2022). "Fine structure in the α decay of the 8+ isomer in 216, 218U". Physical Review C. 106 (2) 024305. doi:10.1103/PhysRevC.106.024305. ISSN 2469-9985. S2CID 251359451.
  9. ↑ Gan, ZaiGuo; Jiang, Jian; Yang, HuaBin; Zhang, ZhiYuan; Ma, Long; Yu, Lin; Wang, JianGuo; Tian, YuLin; Ding, Bing; Huang, TianHeng; Wang, YongSheng; Guo, Song; Sun, MingDao; Wang, KaiLong; Zhou, ShanGui; Ren, ZhongZhou; Zhou, XiaoHong; Xu, HuShan (1 August 2016). "α decay studies of the neutron-deficient uranium isotopes 215-217U". Chinese Science Bulletin. 61 (22): 2502–2511. doi:10.1360/N972015-01316. Retrieved 24 June 2023.
  10. 1 2 3 Bonetti, R.; Guglielmetti, A. (2007). "Cluster radioactivity: an overview after twenty years" (PDF). Romanian Reports in Physics. 59: 301–310. Archived from the original (PDF) on 19 September 2016.
  11. ↑ Trenn, Thaddeus J. (1978). "Thoruranium (U-236) as the extinct natural parent of thorium: The premature falsification of an essentially correct theory". Annals of Science. 35 (6): 581–97. doi:10.1080/00033797800200441.
  12. ↑ Natural and anthropogenic 236U ... uranium and uranium ore samples
  13. ↑ Kromer, Kathrin; Lyu, Chunhai; Bieroń, Jacek; Door, Menno; Enzmann, Lucia; Filianin, Pavel; Gaigalas, Gediminas; Harman, Zoltán; Herkenhoff, Jost; Huang, Wenjia; Keitel, Christoph H.; Eliseev, Sergey; Blaum, Klaus (2024-02-06). "Atomic mass determination of uranium-238". Physical Review C. 109 (2) L021301. American Physical Society (APS). arXiv:2312.17041. Bibcode:2024PhRvC.109b1301K. doi:10.1103/physrevc.109.l021301. ISSN 2469-9985.
  14. ↑ ENSDF analysis available at National Nuclear Data Center. "NuDat 2.x database". Brookhaven National Laboratory.
  15. 1 2 3 Niwase, T.; Watanabe, Y. X.; Hirayama, Y.; et al. (2023). "Discovery of New Isotope 241U and Systematic High-Precision Atomic Mass Measurements of Neutron-Rich Pa-Pu Nuclei Produced via Multinucleon Transfer Reactions" (PDF). Physical Review Letters. 130 (13): 132502-1 – 132502-6. Bibcode:2023PhRvL.130m2502N. doi:10.1103/PhysRevLett.130.132502. PMID 37067317. S2CID 257976576.
  16. ↑ Mukunth, Vasudevan (2023-04-05). "In pursuit of a 'magic number', physicists discover new uranium isotope". The Hindu. ISSN 0971-751X. Retrieved 2023-04-12.
  17. ↑ Yirka, Bob (April 5, 2023). "Previously unknown isotope of uranium discovered". Phys.org. Retrieved 2023-04-12.
  18. ↑ Specifically from thermal neutron fission of uranium-235, e.g. in a typical nuclear reactor.
  19. ↑ Milsted, J.; Friedman, A. M.; Stevens, C. M. (1965). "The alpha half-life of berkelium-247; a new long-lived isomer of berkelium-248". Nuclear Physics. 71 (2): 299. Bibcode:1965NucPh..71..299M. doi:10.1016/0029-5582(65)90719-4.
    "The isotopic analyses disclosed a species of mass 248 in constant abundance in three samples analysed over a period of about 10 months. This was ascribed to an isomer of Bk248 with a half-life greater than 9 [years]. No growth of Cf248 was detected, and a lower limit for the β− half-life can be set at about 104 [years]. No alpha activity attributable to the new isomer has been detected; the alpha half-life is probably greater than 300 [years]."
  20. ↑ This is the heaviest nuclide with a half-life of at least four years before the "sea of instability".
  21. ↑ Excluding those "classically stable" nuclides with half-lives significantly in excess of 232Th; e.g., while 113mCd has a half-life of only fourteen years, that of 113Cd is eight quadrillion years.
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