Abstract: A temperature differential power plant is combined with a nuclear power plant and employs the temperature differential between hot water discharged from cooling the nuclear reactor, steam obtained from the nuclear reactor, and cold water taken in from an outside source such as the sea. The generated output and thermal efficiency of the entire power equipment is thereby increased; the temperature of the hot water discharged from cooling the nuclear reactor is decreased to aid in the recirculation thereof and eliminate hot water pollution; and, only the cold water taken in is discharged with its temperature being controllable so as not to create a cold water pollution problem. Temperature differential power plants can be used in stages with the hot water discharged from cooling the nuclear reactor passing successively from one stage to the next.