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How does nuclear fission produce heat for generating electricity?

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Labeled diagram showing the process of a nuclear power plant with a pressurized-water reactor. Water circulates through the reactor core, heats to produce steam in a steam generator, which drives a turbine connected to an electric generator. Steam is then cooled in a condenser using water from a cooling tower, which releases nonradioactive water vapor. Control rods, pumps, and transmission lines are also indicated. — nuclear power Schematic diagram of a nuclear power plant using a pressurized-water reactor.

Nuclear reactors generate electricity by utilizing nuclear fission, a process where heavy atomic nuclei, typically uranium, split into smaller fragments. This reaction releases a significant amount of energy, which is maintained at a controlled, constant level through a self-sustaining chain reaction.12

In most reactors, this process functions like a furnace to produce heat. A moderator, such as water, surrounds the fuel to slow down neutrons, ensuring they interact efficiently with the uranium. This water also acts as a coolant, absorbing the heat generated by the fission process.32

In a common pressurized-water reactor, this heated primary water is kept under pressure to prevent boiling and is circulated through a heat exchanger. Within the exchanger, the heat is transferred to a secondary water circuit, creating steam that drives a turbine to generate electricity. Throughout this operation, control rods are used to regulate the rate of the reaction or shut it down entirely when necessary.234