A device in which a chain reaction is initiated and controlled with the purpose of producing electrical power is called a nuclear reactor.
A nuclear reactor is a device that is created to control a chain reaction in order to produce a steady flow of neutrons created by the fission of heavy nuclei. Nuclear reactors are differentiated by their uses into research reactors and power reactors. The research reactors are used for conducting basic research and to produce medical isotopes for cancer treatment and imaging, while power reactors are mainly used for generating electricity.