Control rods

Definition

Control rods are devices used in nuclear reactors to control the fission rate of uranium or plutonium. They absorb neutrons and thus regulate the chain reaction within the reactor core.

5 Must Know Facts For Your Next Test

1. Control rods are typically made from materials such as cadmium, hafnium, or boron due to their high neutron absorption capabilities.
2. By absorbing excess neutrons, control rods prevent the reactor from overheating and potentially melting down.
3. They can be inserted or withdrawn from the reactor core to adjust the rate of fission reactions.
4. In an emergency shutdown (scram), control rods are fully inserted into the reactor core to stop the chain reaction quickly.
5. The positioning of control rods is critical for maintaining a stable and controlled nuclear reaction.

Review Questions

• What materials are commonly used to make control rods and why?
• How do control rods help prevent a nuclear reactor meltdown?
• Explain the process and purpose of a 'scram' in a nuclear reactor.

Related terms

Fission:

A nuclear reaction in which an atomic nucleus splits into smaller parts, releasing a large amount of energy.

Reactor Core: The central part of a nuclear reactor where the nuclear reactions occur.

Neutron Moderator: A material used in a nuclear reactor to slow down fast neutrons so that they can sustain a chain reaction.