A power plant, such as a nuclear power plant, and a method for generating peak power therein. The power plant has a thermal accumulator installation composed of main and superheat accumulators so that after the latter are charged steam for peakpower purposes may be derived therefrom in order to operate a turbine through steam generators and superheaters connected to the accumulators through conduits which operate at different pressure-and-temperature levels. The contents of at least some of the accumulators are circulated by a circulating means a plurality of times through the latter accumulators with the circulated contents of any one accumulator being successively directed to flow paths of progressively lower pressure-andtemperature levels during successive circulations of its contents therethrough.