I
Iodine
Z = 53 · Halogen · 126.9 u
Nuclear Engineering Significance
Critical fission product. I-131 (t₁/₂ = 8.02 d) is the most important isotope for public dose in reactor accidents (thyroid uptake). I-135 (t₁/₂ = 6.57 h) decays to Xe-135, the strongest known neutron poison. Iodine behavior in severe accidents drives containment design requirements.
Basic properties
- Atomic number (Z)
- 53
- Standard atomic mass
- 126.9 u
- Category
- Halogen
Isotopes & cross-section data
| Isotope | Mass (A) | Half-life | ZAID | Libraries |
|---|---|---|---|---|
| I-127 | 127 | Stable | .80c.71c.70c | |
| I-129 | 129 | 1.57e7 y | .80c.71c | |
| I-131 | 131 | 8.0207 d | .80c.71c |