Isotopes of uranium

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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
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    • half-lives and are found in appreciable quantity in the 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 214U to 242U (with the exception of 220U). The standard atomic weight of natural uranium
    is 238.02891(3).

    Natural uranium consists of three main

    age of the Earth
    ).

    Uranium-238 is an

    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

    thermal neutrons, i.e., thermal neutron capture has a high probability of inducing fission. A chain reaction can be sustained with a sufficiently large (critical) mass of uranium-235. Uranium-238 is also important because it is fertile: it absorbs neutrons to produce a radioactive isotope that subsequently decays to the isotope plutonium-239
    , which also is fissile.

    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 0.52+0.95
    −0.21     ms         		α 210Th 0+
    215U 92 123 215.026720(11) 1.4(0.9) ms α 211Th 5/2−#
    β+
    ?     		215Pa
    216U[8] 92 124 216.024760(30) 2.25+0.63
    −0.40     ms         		α 212Th 0+
    216mU 2206 keV 0.89+0.24
    −0.16     ms         		α 212Th 8+
    217U[9] 92 125 217.024660(86)# 19.3+13.3
    −5.6     ms         		α 213Th (1/2−)
    β+? 217Pa
    218U[8] 92 126 218.023505(15) 650+80
    −70     μs         		α 214Th 0+
    218mU 2117 keV 390+60
    −50     μs         		α 214Th 8+
    IT? 218U
    219U 92 127 219.025009(14) 60(7) μs α 215Th (9/2+)
    β+? 219Pa
    221U 92 129 221.026323(77) 0.66(14) μs α 217Th (9/2+)
    β+? 221Pa
    222U 92 130 222.026058(56) 4.7(0.7) μs α 218Th 0+
    β+? 222Pa
    223U 92 131 223.027961(63) 65(12) μs α 219Th 7/2+#
    β+? 223Pa
    224U 92 132 224.027636(16) 396(17) μs α 220Th 0+
    β+? 224Pa
    225U 92 133 225.029385(11) 62(4) ms α 221Th 5/2+#
    226U 92 134 226.029339(12) 269(6) ms α 222Th 0+
    227U 92 135 227.0311811(91) 1.1(0.1) min α 223Th (3/2+)
    β+? 227Pa
    228U 92 136 228.031369(14) 9.1(0.2) min α (97.5%) 224Th 0+
    EC (2.5%) 228Pa
    229U 92 137 229.0335060(64) 57.8(0.5) min β+ (80%) 229Pa (3/2+)
    α (20%) 225Th
    230U 92 138 230.0339401(48) 20.23(0.02) d α 226Th 0+
    SF ? (various)
    CD (4.8×10−12%) 208Pb
    22Ne
    231U 92 139 231.0362922(29) 4.2(0.1) d EC 231Pa 5/2+#
    α (.004%) 227Th
    232U 92 140 232.0371548(19) 68.9(0.4) y α 228Th 0+
    CD (8.9×10−10%) 208Pb
    24Ne
    SF (10−12%) (various)
    CD? 204Hg
    28Mg
    233U 92 141 233.0396343(24) 1.592(2)×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) 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%) 208Pb
    26Ne
    CD (≤9×10−12%) 210Pb
    24Ne
    234mU 1421.257(17) keV 33.5(2.0) ms
    IT
    		 234U 6−
    235U[n 13][n 14][n 15] Actin Uranium
    Actino-Uranium     		92 143 235.0439281(12) 7.038(1)×108 y α 231Th 7/2− [0.007204(6)] 0.007198–
    0.007207
    SF (7×10−9%) (various)
    CD (8×10−10%) 215Pb
    20Ne
    CD (8×10−10%) 210Pb
    25Ne
    CD (8×10−10%) 207Hg
    28Mg
    235m1U 0.076737(18) keV 25.7(1) m IT 235U 1/2+
    235m2U 2500(300) keV 3.6(18) ms SF (various)
    236U Thoruranium[10] 92 144 236.0455661(12) 2.342(3)×107 y α 232Th 0+ Trace[n 16]
    SF (9.6×10−8%) (various)
    CD (≤2.0×10−11%)[11] 208Hg
    28Mg
    CD (≤2.0×10−11%)[11] 206Hg
    30Mg
    236m1U 1052.5(6) keV 100(4) ns IT 236U 4−
    236m2U 2750(3) keV 120(2) ns IT (87%) 236U (0+)
    SF (13%) (various)
    237U 92 145 237.0487283(13) 6.752(2) d
    β−
    		 237Np 1/2+ Trace[n 17]
    237mU 274.0(10) keV 155(6) ns IT 237U 7/2−
    238U[n 11][n 13][n 14] Uranium I 92 146 238.050787618(15)[12] 4.468(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 280(6) ns IT (97.4%) 238U 0+
    SF (2.6%) (various)
    239U 92 147 239.0542920(16) 23.45(0.02) min β− 239Np 5/2+ Trace[n 18]
    239m1U 133.7991(10) keV 780(40) ns IT 239U 1/2+
    239m2U 2500(900)# keV >250 ns SF? (various) 0+
    IT? 239U
    240U 92 148 240.0565924(27) 14.1(0.1) h β− 240Np 0+ Trace[n 19]
    α? 236Th
    241U[13] 92 149 241.06031(5) ~40 min[14][15] β− 241Np 7/2+#
    242U 92 150 242.06296(10)[14] 16.8(0.5) 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. ^ a b # – Values marked # are not purely derived from experimental data, but at least partly from trends of neighboring nuclides (TNN).
    9. 237Np
    10. ^ Used in uranium–thorium dating
    11. ^ a b Used in uranium–uranium dating
    12. ^ Intermediate decay product of 238U
    13. ^ a b Primordial radionuclide
    14. ^ a b Used in Uranium–lead dating
    15. ^ Important in nuclear reactors
    16. ^ Intermediate decay product of 244Pu, also produced by neutron capture of 235U
    17. 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[16] by decay chain Half-life
    range (a)
    Fission products of 235U by yield[17]
    4n
    4n + 1
    4n + 2
    4n + 3
    		 4.5–7% 0.04–1.25% <0.001%
    228
    Ra№
    4–6 a
    155
    Euþ
    244
    Cmƒ     		241Puƒ
    250
    Cf
    227
    Ac№
    10–29 a
    		 90Sr 85Kr
    113m
    Cdþ
    232Uƒ 238Puƒ
    243
    Cmƒ
    29–97 a
    137
    Cs
    151
    Smþ
    121m
    Sn
    248Bk[18]
    249
    Cfƒ
    242m
    Amƒ     		141–351 a

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

    241Amƒ
    251Cfƒ[19]
    		 430–900 a
    226Ra№
    247
    Bk     		1.3–1.6 ka
    240Pu
    229
    Th
    246
    Cmƒ
    243
    Amƒ     		4.7–7.4 ka
    245
    Cmƒ
    250
    Cm     		8.3–8.5 ka
    239Puƒ 24.1 ka
    230
    Th№
    231
    Pa№     		32–76 ka
    236
    Npƒ     		233Uƒ 234U№ 150–250 ka 99Tc₡
    126
    Sn
    248
    Cm     		242Pu 327–375 ka 79Se₡
    1.53 Ma
    93
    Zr
    237
    Npƒ     		2.1–6.5 Ma
    135
    Cs₡
    107
    Pd
    236U
    247
    Cmƒ     		15–24 Ma 129I₡
    244Pu 80 Ma

    ... nor beyond 15.7 Ma[20]

    232Th№ 238U№ 235Uƒ№ 0.7–14.1 Ga
    (thermal neutron capture cross section greater than 3k barns)

    Uranium-214

    Uranium-214 is the lightest known isotope of uranium. It was discovered at the Spectrometer for Heavy Atoms and Nuclear Structure (SHANS) at the Heavy Ion Research Facility in Lanzhou, China in 2021, produced by firing argon-36 at tungsten-182. It undergoes alpha decay with a half-life of 0.5 ms.[21][22][23][24]

    Uranium-232

    Main article: Uranium-232

    Uranium-232 has a half-life of 68.9 years and is a side product in the

    fissile with both thermal and fast neutrons.[25][26]

    Uranium-233

    Main article: Uranium-233

    Uranium-233 is a fissile isotope of uranium that is bred from thorium-232 as part of the thorium fuel cycle. 233U 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.[27] 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 the neutron irradiation of thorium-232. When thorium-232 absorbs a

    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

    neptunium-236
    .

    Uranium-234

    Main article: Uranium-234

    234U occurs in natural uranium as an indirect decay product of uranium-238, but makes up only 55 parts per

    protactinium-234. Finally, 234Pa beta decays to 234U.[28][29]

    234U

    thorium-230, except for the small percentage of nuclei that undergo spontaneous fission
    .

    Extraction of rather small amounts of 234U from natural uranium would be feasible using

    alpha emission
    .

    neutrons in a nuclear reactor—becoming 235U.[29][30]

    234U has a

    neptunium-239), because 238U has a much smaller neutron-capture cross section
    of just 2.7 barns.

    Uranium-235

    Main article: Uranium-235

    Uranium-235 makes up about 0.72% of natural uranium. Unlike the predominant isotope

    fissile isotope that is a primordial nuclide
    or found in significant quantity in nature.

    Uranium-235 has a

    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.[31]
    The fission-to-capture ratio improves for faster neutrons.

    Uranium-236

    Main article: 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

    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.[32]

    Uranium-238

    Main article: Uranium-238

    Uranium-238 (238U or U-238) is the most common

    neutron energy
    below the range where fast fission of one or more next-generation nuclei is probable. Doppler broadening of 238U's neutron absorption resonances, increasing absorption as fuel temperature increases, is also an essential negative feedback mechanism for reactor control.

    About 99.284% of natural uranium is uranium-238, which has a half-life of 1.41×1017 seconds (4.468×109 years). Depleted uranium has an even higher concentration of 238U, and even low-enriched uranium (LEU) is still mostly 238U. Reprocessed uranium is also mainly 238U, 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 238U to

    neptunium-239, with a total decay energy of about 1.29 MeV.[33] 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.[34]

    239Np then, with a half-life of about 2.356 days, beta-decays to plutonium-239.

    Uranium-241

    In 2023, in a paper published in Physical Review Letters, a group of researchers based in Korea reported that they had found uranium-241 in an experiment involving 238U+198Pt multinucleon transfer reactions.[35][36] Its half-life is about 40 minutes.[35]

    References

    1. ^
      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. ISSN 1365-3075
      .
    5. ^ "Uranium Isotopes". GlobalSecurity.org. Retrieved 14 March 2012.
    6. doi:10.1088/1674-1137/abddaf
      .
    7. S2CID 231627674
      .
    8. ^
      S2CID 251359451
      .
    9. doi:10.1360/N972015-01316
      . Retrieved 24 June 2023.
    10. doi:10.1080/00033797800200441
      .
    11. ^ a b 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.
    12. ISSN 2469-9985
      .
    13. S2CID 257976576
      .
    14. ^
      ISSN 0971-751X
      . Retrieved 2023-04-12.
    15. ^ Yirka, Bob (April 5, 2023). "Previously unknown isotope of uranium discovered". Phys.org. Retrieved 2023-04-12.
    16. ^ Plus radium (element 88). While actually a sub-actinide, it immediately precedes actinium (89) and follows a three-element gap of instability after polonium (84) where no nuclides have half-lives of at least four years (the longest-lived nuclide in the gap is radon-222 with a half life of less than four days). Radium's longest lived isotope, at 1,600 years, thus merits the element's inclusion here.
    17. thermal neutron fission of uranium-235, e.g. in a typical nuclear reactor
      .
    18. 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]."
    19. sea of instability
      ".
    20. ^ 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.
    21. ^ "Physicists Discover New Uranium Isotope: Uranium-214". Sci-News.com. 14 May 2021. Retrieved 15 May 2021.
    22. S2CID 231627674
      . Retrieved 15 May 2021.
    23. ^ "Lightest-known form of uranium created". Live Science. 3 May 2021. Retrieved 15 May 2021.
    24. ^ "Physicists have created a new and extremely rare kind of uranium". New Scientist. Retrieved 15 May 2021.
    25. ^ "Uranium 232". Nuclear Power. Archived from the original on 26 February 2019. Retrieved 3 June 2019.
    26. ^ "INCIDENT NEUTRON DATA". atom.kaeri.re.kr. 2011-12-14.
    27. ^ C. W. Forsburg; L. C. Lewis (1999-09-24). "Uses For Uranium-233: What Should Be Kept for Future Needs?" (PDF). Ornl-6952. Oak Ridge National Laboratory.
    28. doi:10.1088/1674-1137/41/3/030001
      .
    29. ^
      LCCN 89-25332
      .
    30. ^
      ISSN 1684-2073
      .
    31. doi:10.1103/PhysRev.109.144
      .
    32. PMID 21785255
      .
    33. ^ CRC Handbook of Chemistry and Physics, 57th Ed. p. B-345
    34. ^ CRC Handbook of Chemistry and Physics, 57th Ed. p. B-423
    35. ^ a b Yirka, Bob; Phys.org. "Previously unknown isotope of uranium discovered". phys.org. Retrieved 2023-04-10.
    36. S2CID 257976576
      .
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