Syllabus Coverage: NFC2.1
Burnable poisons are thermal neutron absorbing materials introduced into the fuel to control reactivity. When they absorb a neutron, they do not go on to produce more neutrons — thus they inhibit the chain reaction and become depleted over time (hence “burnable”).
Purposes of burnable poisons:
- Reduce excess reactivity at the beginning of core life (when the fuel is freshest and most reactive)
- Improve power distribution across the core
- Reduce the dependence on control rods