PURPOSE: To contrive to largely reduce the construction cost and largely shorten the construction work term by converting an already constructed hydraulic power station into a nuclear power station.

CONSTITUTION: Reservoir dam lake water for a water turbine of a hydraulic power facility become obsolete is used for cooling of a turbine condenser of nuclear power generation. Temperature of cooling water (a contact area and water pressure or the like) is controlled as cooling temperature due to water pressure (a head drop) is regarded as drop indication temperature. Or excessive hot water is supplied to local ends and used in agriculture, forestry and fishery (a hothouse and fish farming pond or the like). As a measure of an emergency accident (explosion), a cushion cylinder 5 is provided in the intermediate of the circumference of a nuclear reactor 4, many small holes are drilled in the whole of its side and pressure is cushioned. In addition, the pressure is directly decreased by an upper opening 7 and a cylinder 5, jetting is performed upward from the opening 7, an upper emergency break plate 8 is broken and jetting is conducted to an upper layer from an upper exhaust opening 3 (the same phenomenon as a volcano eruption).