Isotopes of uranium
List of isotopes
Abbreviations: CD: Cluster decay EC: Electron capture IT: Isomeric transition SF: Spontaneous fission Bold for stable isotopes, bold italics for nearly-stable isotopes (half-life longer than the age of the universe) Used in uranium–thorium dating Used in uranium–uranium dating Intermediate decay product of ²³⁸U Primordial radionuclide Used in Uranium–lead dating Important in nuclear reactors

Isotopes of uranium

Section Title: List of isotopes
Table Section Text: Abbreviations: CD: Cluster decay EC: Electron capture IT: Isomeric transition SF: Spontaneous fission Bold for stable isotopes, bold italics for nearly-stable isotopes (half-life longer than the age of the universe) Used in uranium–thorium dating Used in uranium–uranium dating Intermediate decay product of ²³⁸U Primordial radionuclide Used in Uranium–lead dating Important in nuclear reactors

nuclide symbol	historic name	Z(p)	N(n)	isotopic mass (u)	half-life	decay mode(s)	daughter isotope(s)	nuclear spin and parity	representative isotopic composition (mole fraction)	range of natural variation (mole fraction)

excitation energy

215U	92	123	215.026760(90)	2.24 ms	α	211Th	5/2−#

216U	92	124	216.024760(30)	4.3 ms	α	212Th	0+

217U	92	125	217.02437(9)	26(14) ms [16(+21−6) ms]	α	213Th	1/2−#

218U	92	126	218.02354(3)	6(5) ms	α	214Th	0+

219U	92	127	219.02492(6)	55(25) µs [42(+34−13) µs]	α	215Th	9/2+#

221U	92	129	221.02640(11)#	0.66(14) µs	α	217Th	(9/2+)

222U	92	130	222.02609(11)#	1.4(7) µs [1.0(+10−4) µs]	α	218Th	0+

β+ (10−6%)	222Pa

223U	92	131	223.02774(8)	21(8) µs [18(+10−5) µs]	α	219Th	7/2+#

224U	92	132	224.027605(27)	940(270) µs	α	220Th	0+

225U	92	133	225.02939#	61(4) ms	α	221Th	(5/2+)#

226U	92	134	226.029339(14)	269(6) ms	α	222Th	0+

227U	92	135	227.031156(18)	1.1(1) min	α	223Th	(3/2+)

β+ (.001%)	227Pa

228U	92	136	228.031374(16)	9.1(2) min	α (95%)	224Th	0+

EC (5%)	228Pa

229U	92	137	229.033506(6)	58(3) min	β+ (80%)	229Pa	(3/2+)

α (20%)	225Th

230U	92	138	230.033940(5)	20.8 d	α	226Th	0+

SF (1.4×10−10%)	(various)

β+β+ (rare)	230Th

231U	92	139	231.036294(3)	4.2(1) d	EC	231Pa	(5/2)(+#)

α (.004%)	227Th

232U	92	140	232.0371562(24)	68.9(4) y	α	228Th	0+

CD (8.9×10−10%)	208Pb 24Ne

CD (5×10−12%)	204Hg 28Mg

SF (10−12%)	(various)

233U	92	141	233.0396352(29)	1.592(2)×105 y	α	229Th	5/2+

SF (6×10−9%)	(various)

CD (7.2×10−11%)	209Pb 24Ne

CD (1.3×10−13%)	205Hg 28Mg

234U	Uranium II	92	142	234.0409521(20)	2.455(6)×105 y	α	230Th	0+	[0.000054(5)]	0.000050– 0.000059

SF (1.73×10−9%)	(various)

CD (1.4×10−11%)	206Hg 28Mg

CD (9×10−12%)	184Hf 26Ne 24Ne

234mU	1421.32(10) keV	33.5(20) ms	6−

235U	Actin Uranium Actino-Uranium	92	143	235.0439299(20)	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%)	186Hf 25Ne 24Ne

235mU	0.0765(4) keV	~26 min	IT	235U	1/2+

236U	Thoruranium	92	144	236.045568(2)	2.342(3)×107 y	α	232Th	0+

SF (9.6×10−8%)	(various)

236m1U	1052.89(19) keV	100(4) ns	(4)−

236m2U	2750(10) keV	120(2) ns	(0+)

237U	92	145	237.0487302(20)	6.75(1) d	β−	237Np	1/2+

238U	Uranium I	92	146	238.0507882(20)	4.468(3)×109 y	α	234Th	0+	[0.992742(10)]	0.992739– 0.992752

SF (5.45×10−5%)	(various)

β−β− (2.19×10−10%)	238Pu

238mU	2557.9(5) keV	280(6) ns	0+

239U	92	147	239.0542933(21)	23.45(2) min	β−	239Np	5/2+

239m1U	20(20)# keV	>250 ns	(5/2+)

239m2U	133.7990(10) keV	780(40) ns	1/2+

240U	92	148	240.056592(6)	14.1(1) h	β−	240Np	0+

α (10−10%)	236Th

242U	92	150	242.06293(22)#	16.8(5) min	β−	242Np	0+

Sentence(s)

237U has a half life of about 6.75(1) days.

final_sentence: 237U has a half life of about 6.75(1) days.