Nuclear Reactors
Physics: Edexcel IGCSE, topic 7.2.6
Nuclear Reactors - Controlled Chain Reaction
Nuclear fission produces a chain reaction - the neutrons released by one reaction cause another reaction to occur. Control rods and moderators are used to control the reactions taking place.
Control rods
- Control rods are used to control the number of neutrons in the reactor.
- They can absorb neutrons to slow the rate of reaction.
- Removing control rods therefore increases the rate of reaction.
Moderators
- Moderators control the speed at which the neutrons are travelling in the reactor.
- Surprisingly, the slower a neutron is travelling, the more likely they are to trigger a fission reaction.