Primordial nuclide
List of 34 radioactive primordial nuclides and measured half-lives

Primordial nuclide

Section Title: List of 34 radioactive primordial nuclides and measured half-lives
Table Section Text: None

No.	Nuclide	Energy	Half- life (years)	Decay mode	Decay energy (MeV)	Approx. ratio half-life to age of universe

253	128Te	8.743261	2.2×1024	2 β−	2.530	160 trillion

254	124Xe	8.778264	1.8×1022	KK	2.864	1 trillion

255	78Kr	9.022349	9.2×1021	KK	2.846	670 billion

256	136Xe	8.706805	2.165×1021	2 β−	2.462	150 billion

257	76Ge	9.034656	1.8×1021	2 β−	2.039	130 billion

258	130Ba	8.742574	1.2×1021	KK	2.620	90 billion

259	82Se	9.017596	1.1×1020	2 β−	2.995	8 billion

260	116Cd	8.836146	3.102×1019	2 β−	2.809	2 billion

261	48Ca	8.992452	2.301×1019	2 β−	4.274, .0058	2 billion

262	96Zr	8.961359	2.0×1019	2 β−	3.4	1 billion

263	209Bi	8.158689	1.9×1019	α	3.137	1 billion

264	130Te	8.766578	8.806×1018	2 β−	.868	600 million

265	150Nd	8.562594	7.905×1018	2 β−	3.367	600 million

266	100Mo	8.933167	7.804×1018	2 β−	3.035	600 million

267	151Eu	8.565759	5.004×1018	α	1.9644	300 million

268	180W	8.347127	1.801×1018	α	2.509	100 million

269	50V	9.055759	1.4×1017	β+ or β−	2.205, 1.038	10 million

270	113Cd	8.859372	7.7×1015	β−	.321	600,000

271	148Sm	8.607423	7.005×1015	α	1.986	500,000

272	144Nd	8.652947	2.292×1015	α	1.905	200,000

273	186Os	8.302508	2.002×1015	α	2.823	100,000

274	174Hf	8.392287	2.002×1015	α	2.497	100,000

275	115In	8.849910	4.4×1014	β−	.499	30,000

276	152Gd	8.562868	1.1×1014	α	2.203	8000

277	190Pt	8.267764	6.5×1011	α	3.252	47

278	147Sm	8.610593	1.061×1011	α	2.310	7.7

279	138La	8.698320	1.021×1011	K or β−	1.737, 1.044	7.4

280	87Rb	9.043718	4.972×1010	β−	.283	3.6

281	187Re	8.291732	4.122×1010	β−	.0026	3

282	176Lu	8.374665	3.764×1010	β−	1.193	2.7

283	232Th	7.918533	1.406×1010	α or SF	4.083	1

284	238U	7.872551	4.471×109	α or SF or 2 β−	4.270	0.3

285	40K	8.909707	1.25×109	β− or K or β+	1.311, 1.505, 1.505	0.09

286	235U	7.897198	7.04×108	α or SF	4.679	0.05

Sentence(s)

The four shortest-lived primordial nuclides (i.e. nuclides with shortest half-lives) are ²³² Th, ²³⁸ U, ⁴⁰ K, and ²³⁵ U.

final_sentence: The four shortest-lived primordial nuclides (i.e. nuclides with shortest half-lives) are ²³² Th, ²³⁸ U, ⁴⁰ K, and ²³⁵ U.