Isotopes of uranium

Nuclides with atomic number of 92 but with different mass numbers

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±0.00003[3]
* 238.03±0.01 (abridged)[4]

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Uranium (92U) is a naturally occurring radioactive element that has no stable isotope. It has two primordial isotopes, uranium-238 and uranium-235, that have long 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).

Naturally occurring uranium is composed of three major isotopes, uranium-238 (99.2739–99.2752% natural abundance), uranium-235 (0.7198–0.7202%), and uranium-234 (0.0050–0.0059%).[5] All three isotopes are radioactive (i.e., they are radioisotopes), and the most abundant and stable is uranium-238, with a half-life of 4.4683×109 years (close to 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 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[edit]

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)

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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  | 238.0507869(16)  | 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+  |  |
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 18] |
α?  | 236Th
241U[12] |  | 92  | 149  | 241.06031(5)  | ~40 min[13][14] | β− | 241Np  | 7/2+#  |
242U  |  | 92  | 150  | 242.06296(10)[13] | 16.8(0.5) min  | β− | 242Np  | 0+  |  |
This table header & footer:

* view

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. ^ Intermediate decay product of 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. ^ Neutron capture product, parent of trace quantities of 237Np
18. ^ Intermediate decay product of 244Pu

## Actinides vs fission products[edit]

Actinides and fission products by half-life

* v
* t
* e

Actinides[15] by decay chain | Half-life
range (a)  | Fission products of 235U by yield[16]
4n | 4n \+ 1 | 4n \+ 2 | 4n \+ 3 | 4.5–7%  | 0.04–1.25%  | <0.001%
228Ra№ |  |  |  | 4–6 a |  | 155Euþ |
244Cmƒ | 241Puƒ | 250Cf  | 227Ac№ | 10–29 a | 90Sr  | 85Kr  | 113mCdþ
232Uƒ |  | 238Puƒ | 243Cmƒ | 29–97 a | 137Cs  | 151Smþ | 121mSn
248Bk[17] | 249Cfƒ | 242mAmƒ |  | 141–351 a  |

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

| 241Amƒ |  | 251Cfƒ[18] | 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₡
|  |  |  | 1.53 Ma | 93Zr
| 237Npƒ |  |  | 2.1–6.5 Ma | 135Cs₡ | 107Pd
236U  |  |  | 247Cmƒ | 15–24 Ma |  | 129I₡
244Pu  |  |  |  | 80 Ma  |

... nor beyond 15.7 Ma[19]

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)

## Uranium-214[edit]

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.[20][21][22][23]

## Uranium-232[edit]

Main article: 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 233U as the fissile material, because the intense gamma radiation emitted by 208Tl (a daughter of 232U, produced relatively quickly) makes the 233U 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.[24][25]

## Uranium-233[edit]

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. Uranium-233 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.[26] 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 neutron, it becomes thorium-233, which has a half-life of only 22 minutes. Thorium-233 decays into protactinium-233 through beta decay. 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[edit]

Main article: Uranium-234

Uranium-234 is an isotope of uranium. In natural uranium and in uranium ore, 234U occurs as an indirect decay product of uranium-238, but it makes up only 0.0055% (55 parts per million) of the raw uranium because its half-life of just 245,500 years is only about 1/18,000 as long as that of 238U. The path of production of 234U via nuclear decay is as follows: 238U nuclei emit an alpha particle to become thorium-234. Next, with a short half-life, a 234Th nucleus emits a beta particle to become protactinium-234. Finally, 234Pa nuclei each emit another beta particle to become 234U nuclei.[27][28]

234U nuclei usually last for hundreds of thousands of years, but then they decay by alpha emission to 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 isotope separation, similar to that used for regular uranium-enrichment. However, there is no real demand in chemistry, physics, or engineering for isolating 234U. Very small pure samples of 234U can be extracted via the chemical ion-exchange process—from samples of plutonium-238 that have been aged somewhat to allow some decay to 234U via alpha emission.

Enriched uranium contains more 234U 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 235U. The increased percentage of 234U in enriched natural uranium is acceptable in current nuclear reactors, but (re-enriched) reprocessed uranium might contain even higher fractions of 234U, which is undesirable.[29] This is because 234U is not fissile, and tends to absorb slow neutrons in a nuclear reactor—becoming 235U.[28][29]

234U 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. 234U is converted to 235U more easily and therefore at a greater rate than uranium-238 is to plutonium-239 (via neptunium-239), because 238U has a much smaller neutron-capture cross section of just 2.7 barns.

## Uranium-235[edit]

Main article: Uranium-235

Uranium-235 is an isotope of uranium making 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 703.8 million years. It was discovered in 1935 by Arthur Jeffrey Dempster. Its (fission) nuclear cross section for slow thermal neutron is about 504.81 barns. 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.[30] The fission-to-capture ratio improves for faster neutrons.

## Uranium-236[edit]

Main article: Uranium-236

Uranium-236 is an isotope of uranium with a half-life of about 23 million years that 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[edit]

Uranium-237 is an isotope of uranium. It has a half-life of about 6.75(1) 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.[31]

## Uranium-238[edit]

Main article: Uranium-238

Uranium-238 (238U or U-238) is the most common isotope of uranium found in nature. It is not fissile, but is a fertile material: 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 238U's neutron absorption resonances, increasing absorption as fuel temperature increases, is also an essential negative feedback mechanism for reactor control.

Around 99.284% of natural uranium is uranium-238, which has a half-life of 1.41×1017 seconds (4.468×109 years, or 4.468 billion years). Depleted uranium has an even higher concentration of the 238U isotope, and even low-enriched uranium (LEU), while having a higher proportion of the uranium-235 isotope (in comparison to depleted uranium), 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[edit]

Uranium-239 is an isotope of uranium. It is usually produced by exposing 238U to neutron radiation in a nuclear reactor. 239U has a half-life of about 23.45 minutes and decays into neptunium-239 through beta decay, with a total decay energy of about 1.29 MeV.[32] 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.[33]

239Np further decays to plutonium-239 also through beta decay with a half-life of about 2.356 days, in a second important step that ultimately produces fissile 239Pu (used in weapons and for nuclear power), from 238U in reactors.

## Uranium-241[edit]

Uranium-241 is an isotope of uranium. 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.[34][35] Its half-life is approximately 40 minutes.[34]

## References[edit]

1. ^ a b c d e 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; et al. (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.
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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. ^ 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.
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. ^ 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. doi:10.1103/PhysRevLett.130.132502. PMID 37067317. S2CID 257976576.
13. ^ a b 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.
14. ^ Yirka, Bob (April 5, 2023). "Previously unknown isotope of uranium discovered". Phys.org. Retrieved 2023-04-12.
15. ^ 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.
16. ^ Specifically from thermal neutron fission of uranium-235, e.g. in a typical nuclear reactor.
17. ^ 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]."
18. ^ This is the heaviest nuclide with a half-life of at least four years before the "sea of instability".
19. ^ 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 nearly eight quadrillion years.
20. ^ "Physicists Discover New Uranium Isotope: Uranium-214". Sci-News.com. 14 May 2021. Retrieved 15 May 2021.
21. ^ Zhang, Z. Y.; et al. (2021). "New α -Emitting Isotope 214 U 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. Retrieved 15 May 2021.
22. ^ "Lightest-known form of uranium created". Live Science. 3 May 2021. Retrieved 15 May 2021.
23. ^ "Physicists have created a new and extremely rare kind of uranium". New Scientist. Retrieved 15 May 2021.
24. ^ "Uranium 232". Nuclear Power. Archived from the original on 26 February 2019. Retrieved 3 June 2019.
25. ^ "INCIDENT NEUTRON DATA". atom.kaeri.re.kr. 2011-12-14.
26. ^ 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.
27. ^ Audi, G.; Kondev, F. G.; Wang, M.; Huang, W. J.; Naimi, S. (2017). "The NUBASE2016 evaluation of nuclear properties" (PDF). Chinese Physics C. 41 (3): 030001. Bibcode:2017ChPhC..41c0001A. doi:10.1088/1674-1137/41/3/030001.
28. ^ a b Ronen, Y., ed. (1990). High converting water reactors. CRC Press. p. 212\. ISBN 0-8493-6081-1. LCCN 89-25332.
29. ^ a b Use of Reprocessed Uranium (PDF). Technical Document. Vienna: International Atomic Energy Agency. 2009. ISBN 978-92-0-157109-0. ISSN 1684-2073.
30. ^ B. C. Diven; J. Terrell; A. Hemmendinger (1 January 1958). "Capture-to-Fission Ratios for Fast Neutrons in U235". Physical Review Letters. 109 (1): 144–150. Bibcode:1958PhRv..109..144D. doi:10.1103/PhysRev.109.144.
31. ^ Ikeda, Nagao (July 25, 2011). "The discoveries of uranium 237 and symmetric fission — From the archival papers of Nishina and Kimura". Proceedings of the Japan Academy. Series B, Physical and Biological Sciences. 87 (7): 371–376. doi:10.2183/pjab.87.371. PMC 3171289. PMID 21785255.
32. ^ CRC Handbook of Chemistry and Physics, 57th Ed. p. B-345
33. ^ CRC Handbook of Chemistry and Physics, 57th Ed. p. B-423
34. ^ a b Yirka, Bob; Phys.org. "Previously unknown isotope of uranium discovered". phys.org. Retrieved 2023-04-10.
35. ^ Niwase, T.; Watanabe, Y. X.; Hirayama, Y.; Mukai, M.; Schury, P.; Andreyev, A. N.; Hashimoto, T.; Iimura, S.; Ishiyama, H.; Ito, Y.; Jeong, S. C.; Kaji, D.; Kimura, S.; Miyatake, H.; Morimoto, K. (2023-03-31). "Discovery of New Isotope $^{241}\mathrm{U}$ and Systematic High-Precision Atomic Mass Measurements of Neutron-Rich Pa-Pu Nuclei Produced via Multinucleon Transfer Reactions". Physical Review Letters. 130 (13): 132502. doi:10.1103/PhysRevLett.130.132502. PMID 37067317. S2CID 257976576.

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Isotopes of the chemical elements

| Group | 1 | 2 |  | 3 | 4 | 5 | 6 | 7 | 8 | 9 | 10 | 11 | 12 | 13 | 14 | 15 | 16 | 17 | 18

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Period | Hydrogen and
alkali metals  | Alkaline
earth metals  |  |  |  |  |  |  |  |  |  |  |  |  |  | Pnicto­gens  | Chal­co­gens  | Halo­gens  | Noble gases
① |

Isotopes § List

1  |  |

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3  |

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4  |  |

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5  |

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6  |

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7  |

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8  |

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9  |

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③ |

Isotopes § List

11  |

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12  |  |

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13  |

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14  |

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15  |

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34  |

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35  |

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38  |  |

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⑥ |

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55  |

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56  |  |

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71  |

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72  |

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76  |

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78  |

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80  |

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81  |

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82  |

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83  |

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84  |

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85  |

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⑦ |

Isotopes § List

87  |

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88  |  |

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103  |

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104  |

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105  |

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106  |

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107  |

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109  |

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110  |

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111  |

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112  |

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113  |

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114  |

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115  |

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116  |

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117  |

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118
⑧ |

Isotopes § List

Uue

119  |

Isotopes § List

Ubn

120
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62  |

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65  |

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66  |

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67  |

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68  |

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69  |

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70  |
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89  |

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90  |

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91  |

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92  |

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93  |

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94  |

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* Table of nuclides
* Categories: Isotopes
* Tables of nuclides
* Metastable isotopes
* Isotopes by element

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