How does a nuclear reactor use fission to produce heat?

A nuclear reactor produces heat through a controlled nuclear fission chain reaction. This process begins when a heavy atomic nucleus, such as uranium-235, splits into smaller fragments, releasing a significant amount of energy and additional neutrons.12

These emitted neutrons can strike other fissile nuclei, inducing further fissions and creating a self-sustaining chain reaction. In a reactor, this reaction is maintained at a steady state by using control rods—made of materials like boron, cadmium, or hafnium—to absorb excess neutrons and regulate the rate of fission.12

The majority of the energy released during fission is deposited as heat directly into the fuel. To manage this, a coolant—such as water, gas, or liquid metal—is circulated through the reactor core. This coolant absorbs the thermal energy from the fuel and transports it away, where it is typically used to generate steam to drive turbines for electricity production.231456