A power-generation plant 10 including a gas turbine 11; a fuel-gas cooler 13; and an extraction line 24 that guides the fuel gas extracted from an intermediate stage of a fuel-gas compressor 12 to the fuel-gas cooler 13; a first level detector 61 that detects whether a level of the coolant accumulated at a bottom portion of the fuel-gas cooler 13 has reached a predetermined level; and a controller that stops the gas turbine 11 on the basis of a detection signal sent from the first level detector 61 and that outputs a command signal for stopping a coolant pump 53 that supplies the coolant to the spray nozzles 44 and 45.