U
Uranium
Z = 92 · Actinide · 238.0 u
Nuclear Engineering Significance
Primary nuclear fuel. U-235 (0.72% natural abundance) is the only naturally occurring fissile isotope. U-238 is fertile — it captures neutrons to breed Pu-239. Enrichment level is the single most important parameter in reactor design. UO₂ is the standard fuel form; metallic U is used in some research and fast reactor fuels.
Basic properties
- Atomic number (Z)
- 92
- Standard atomic mass
- 238.0 u
- Category
- Actinide
Isotopes & cross-section data
| Isotope | Mass (A) | Half-life | ZAID | Libraries |
|---|---|---|---|---|
| U-233 | 233 | 1.592e5 y | .80c.71c.70c | |
| U-234 | 234 | 2.455e5 y | .80c.71c.70c | |
| U-235 | 235 | 7.04e8 y | .80c.71c.70c | |
| U-236 | 236 | 2.342e7 y | .80c.71c.70c | |
| U-238 | 238 | 4.468e9 y | .80c.71c.70c |