To lower the cost of facilities.

A high pressure steam turbine bypass pipe 31 is connected to steam pipes 17 and 19 connected to the inlet side and outlet side of a high pressure steam turbine 18 so as to be parallel with the high pressure steam turbine 18. A spray part 30 capable of atomizing spray water 67 by a spray nozzle 33 is provided in the intermediate part of the high pressure steam turbine bypass pipe 31. An emergent spray water supply pipe 58 having an end connected to the spray nozzle 33 and an emergent spray water supply pump 57 at its intermediate part communicates with the outlet side of a condenser 24. An emergent spray water storing tank 60 in which emergent spray water 61 can be pushed out into the emergent spray water supply pipe 58 under gas pressure is connected to the downstream side of the connecting part of the emergent spray water supply pump 57 to the emergent spray water supply pipe 58.