Cs
Cesium
Z = 55 · Alkali Metal · 132.9 u
Nuclear Engineering Significance
Major fission product. Cs-137 (t₁/₂ = 30.2 y) is a dominant contributor to spent fuel radioactivity and external dose, and the primary long-term ground contamination isotope in reactor accidents (Chernobyl, Fukushima). Cs-134 (t₁/₂ = 2.06 y) is used as a burnup indicator.
Basic properties
- Atomic number (Z)
- 55
- Standard atomic mass
- 132.9 u
- Category
- Alkali Metal
Isotopes & cross-section data
View in ALLEN →| Isotope | Mass (A) | Half-life | ZAID | Libraries | σ(E) |
|---|---|---|---|---|---|
| Cs-133 | 133 | Stable | .80c.71c | View → | |
| Cs-134 | 134 | 2.0652 y | .80c.71c | View → | |
| Cs-135 | 135 | 2.3e6 y | .80c.71c | View → | |
| Cs-137 | 137 | 30.17 y | .80c.71c | View → |