Britannica
Sources used in this answer
Why does a nuclear reactor need a coolant?
Created from Britannica articles
using AI.
AI can make mistakes, so verify using Britannica articles.
nuclear fission
Italian-born physicist Enrico Fermi explaining a problem in physics, c. 1950. He was awarded the 1938 Nobel Prize for Physics.
A nuclear reactor requires a coolant primarily to remove the intense heat generated during the process of nuclear fission. When a nucleus splits, a significant portion of the energy is deposited directly into the fuel; without a cooling system to circulate this heat away, the temperature would build up rapidly, potentially causing the fuel to melt.1
Beyond preventing structural damage, the coolant serves two other critical functions:
- Energy Conversion: In power reactors, the coolant transports thermal energy from the core to steam-generating equipment, where it is converted into electric power.23
- Moderation: In many designs, such as light-water reactors, the coolant also acts as a moderator. It slows down high-energy neutrons, which increases the probability of further fission events and helps sustain the chain reaction.24
Because maintaining core integrity is essential for safety, reactors are equipped with sophisticated cooling systems designed to operate reliably under both normal and abnormal conditions.15