Gd
Gadolinium
Z = 64 · Lanthanide · 157.3 u
Nuclear Engineering Significance
Burnable absorber with extremely high thermal absorption cross-section (σ_a ≈ 49,000 b for natural Gd, dominated by Gd-155 and Gd-157). Used as Gd₂O₃ mixed into fuel pellets to control excess reactivity at beginning of life. Self-shielding effects in gadolinia-bearing fuel pins require careful spatial discretization in transport calculations.
Basic properties
- Atomic number (Z)
- 64
- Standard atomic mass
- 157.3 u
- Category
- Lanthanide
Isotopes & cross-section data
| Isotope | Mass (A) | Half-life | ZAID | Libraries |
|---|---|---|---|---|
| Gd-152 | 152 | 1.08e14 y | .80c.71c.70c | |
| Gd-154 | 154 | Stable | .80c.71c.70c | |
| Gd-155 | 155 | Stable | .80c.71c.70c | |
| Gd-156 | 156 | Stable | .80c.71c.70c | |
| Gd-157 | 157 | Stable | .80c.71c.70c | |
| Gd-158 | 158 | Stable | .80c.71c.70c | |
| Gd-160 | 160 | Stable | .80c.71c.70c |