Control rods

Definition

Control rods are devices made from materials like boron or cadmium that absorb neutrons and regulate the rate of fission reactions within a nuclear reactor. By inserting or withdrawing control rods, operators can control the power output and prevent overheating.

Related terms

Moderator: A substance (like water or graphite) used in a reactor to slow down fast-moving neutrons so they can cause more fission reactions.

Meltdown: A severe accident in which excessive heat causes fuel rods to overheat and melt inside a nuclear reactor.

Criticality: The state at which there is just enough neutron multiplication to sustain a self-sustaining chain reaction without any increase or decrease in power level.