The type of reaction that occurs in a nuclear power plant is known as nuclear fission. During this process, the nuclei of heavy atoms, such as uranium-235 or plutonium-239, are split into smaller nuclei upon absorption of a neutron. This reaction releases a massive amount of energy in the form of heat, which is used to generate steam that drives turbines to produce electricity. Nuclear fission is a critical component of nuclear energy production, providing an alternative to fossil fuels while also raising concerns about safety and waste management.