Uranium isotopes (U, Z = 92) — complete ground-state set

Notation. Nuclides written with mass number as left superscript (e.g., ²³⁸U).
Columns. Stable? — ground states only (Uranium has no absolutely stable isotopes, but several are long-lived, effectively primordial). Half-lives = evaluated values; # = extrapolated/systematics. Decay → daughter(s) shows main branches. Radiation: α, β⁻, SF (spontaneous fission). Origin: natural/synthetic. Uses: M medical, I industrial, R research, N nuclear fuel.
Primary data spine: evaluated Isotopes of uranium (ENSDF/NUBASE 2020).

Table — ground states

Nuclide	Z	A	Stable?	Half-life	Decay → daughter(s)	Radiation	Origin	Notes & Uses
²¹⁷U	92	217	No	16 µs	α → ²¹³Th	α	Fusion-evap.	R.
²¹⁸U	92	218	No	52 µs	α → ²¹⁴Th	α	Fusion-evap.	R.
²¹⁹U	92	219	No	0.76 ms	α → ²¹⁵Th	α	Fusion-evap.	R.
²²⁰U	92	220	No	1.0 µs	α → ²¹⁶Th	α	Fusion-evap.	R.
²²¹U	92	221	No	0.6 ms	α → ²¹⁷Th	α	Fusion-evap.	R.
²²²U	92	222	No	1.0 ms	α → ²¹⁸Th	α	Synthetic	R.
²²³U	92	223	No	0.60 ms	α → ²¹⁹Th	α	Synthetic	R.
²²⁴U	92	224	No	38.0 ms	α → ²²⁰Th	α	Synthetic	R.
²²⁵U	92	225	No	1.0 s	β⁻ → ²²⁵Np	β⁻	Synthetic	R.
²²⁶U	92	226	No	0.3 s	α → ²²²Th	α	Synthetic	R.
²²⁷U	92	227	No	1.9 min	β⁻ → ²²⁷Np	β⁻	Synthetic	R.
²²⁸U	92	228	No	9.1 min	β⁻ → ²²⁸Np	β⁻	Synthetic	R.
²²⁹U	92	229	No	1.0 min	β⁻ → ²²⁹Np	β⁻	Synthetic	R.
²³⁰U	92	230	No	20.8 d	α → ²²⁶Th	α	Synthetic (n,γ on ²³⁹Pu)	R.
²³¹U	92	231	No	4.2 d	β⁻ → ²³¹Np	β⁻	Synthetic	R.
²³²U	92	232	No	68.9 y	α → ²²⁸Th	α	Byproduct of Th fuel cycle	R/I: γ-emitter; handling hazard in Th reactors.
²³³U	92	233	No	1.592 × 10⁵ y	α → ²²⁹Th	α	Synthetic (Th fuel cycle)	Nuclear fuel; fissile like ²³⁵U.
²³⁴U	92	234	No	2.46 × 10⁵ y	α → ²³⁰Th	α	Natural (U-238 chain)	Present in uranium ores (~0.005%).
²³⁵U	92	235	No	7.04 × 10⁸ y	α → ²³¹Th	α	Natural (primordial)	Fissile isotope in reactors & weapons.
²³⁶U	92	236	No	2.34 × 10⁷ y	α → ²³²Th	α	Byproduct (from ²³⁵U neutron capture)	Used as tracer in spent fuel.
²³⁷U	92	237	No	6.75 d	β⁻ → ²³⁷Np	β⁻	Synthetic	R.
²³⁸U	92	238	No	4.468 × 10⁹ y	α → ²³⁴Th	α	Natural (primordial)	Main isotope of natural uranium (~99.3%); fertile → ²³⁹Pu.
²³⁹U	92	239	No	23.45 min	β⁻ → ²³⁹Np → ²³⁹Pu	β⁻	Synthetic (²³⁸U(n,γ))	First step toward plutonium-239 production.
²⁴⁰U	92	240	No	14.1 h	β⁻ → ²⁴⁰Np	β⁻	Synthetic	R.
²⁴¹U	92	241	No	40 min	β⁻ → ²⁴¹Np	β⁻	Synthetic	R.
²⁴²U	92	242	No	16.8 min	β⁻ → ²⁴²Np	β⁻	Synthetic	R.
²⁴³U	92	243	No	1.6 min	β⁻ → ²⁴³Np	β⁻	Synthetic	R.
²⁴⁴U	92	244	No	285 ns	SF / β⁻	SF; β⁻	Synthetic	R.

Natural isotopes of uranium

²³⁵U (7.04 × 10⁸ y) — fissile, ~0.72% of natural uranium; vital for nuclear power and weapons.
²³⁸U (4.468 × 10⁹ y) — fertile, ~99.3% of natural uranium; main isotope in ores.
²³⁴U (2.46 × 10⁵ y) — minor natural isotope, part of U-238 chain.
Trace isotopes from chains: ²³⁰U, ²³²U, ²³⁶U appear in fuel cycles or decay series.

Applied & research highlights

Nuclear fuel. ²³⁵U and ²³³U are fissile isotopes used in reactors and nuclear weapons. ²³⁸U is fertile → ²³⁹Pu via neutron capture and β⁻ decays.
Geochronology. U isotopes form the basis of U–Pb dating (²³⁸U → ²⁰⁶Pb, ²³⁵U → ²⁰⁷Pb).
Environmental tracing. ²³⁶U is used as a marker of spent fuel in the environment.
Hazards. ²³²U is a byproduct in Th-based cycles, complicating handling due to intense γ emission from its daughters.
Fundamental research. Exotic U isotopes studied for nuclear structure and fission properties.

Totals — Uranium (Z = 92)

Ground-state isotopes listed: 28 (A = 217–244).
Stable: 0 (but ²³²Th, ²³⁵U, and ²³⁸U are long-lived primordial).
Unstable: 28.

Running cumulative totals (through U):
From Pa ledger: ≥ 2 974 total, 252 stable, ≥ 2 721 unstable.
Add U (+28 total, +0 stable, +28 unstable) → ≥ 3 002 total, 252 stable, ≥ 2 749 unstable.

Sources

Full isotopic list (A = 217–244): Isotopes of uranium (ENSDF/NUBASE 2020 backbone).
Uranium fuel cycle & geochronology: IAEA and geology references.
²³²U hazard & ²³⁶U tracing: reactor fuel-cycle analyses.
²³⁸U and ²³⁵U dating: foundational geochronology literature.

Next element: Neptunium — Np (Z = 93).