A power plant that uses the energy produced by the fission of nuclear fuel to generate electricity. A nuclear power plant consists of a nuclear part, a reactor, in which a controlled fission reaction takes place. The heat generated is transferred through a cooling circuit to the non-nuclear part. Here, energy is transferred to water, and the steam produced turns a turbogenerator, which generates electricity. In high-temperature, gas-cooled reactors, hot gas exiting the reactor is used to drive the gas turbine; in boiling water reactors, the steam turbine is driven by steam generated directly in the reactor. There are many types of nuclear reactors; the most common types used in nuclear power plants are water-cooled PWRs and BWRs. In 2023, there were over 170 nuclear power plants in operation worldwide.