Abstract: A passive depressurization system for use during cold shutdown of a pressurized water reactor receives saturated steam from the reactor's pressurizer, condenses the steam to water, and returns the water to a nozzle within the pressurizer in order to provide a cooling spray which condenses steam within the pressurizer. The depressurization system may include coiled tubing, which is connected to input and output ports of the depressurization system by redundant valves, or a condenser formed by a housing having air vents provided by vent elements through the housing.

Abstract: A method of testing the operability of check valves having a pivotal closure disk wherein a check valve is provided having a valve body and first sealing member of nonmagnetic material and a pivotal closure disk and second sealing member of magnetic material, and a magnetic field is applied in a direction which causes the closure disk to move away from the first sealing member. The attraction between the magnetic field generator and the closure disk is measured to determine the relative position of the closure disk to the first sealing member and thus the operability of the valve.

Abstract: Apparatus for reducing the pressure in a pressurizer of a pressurized water type cooling system for a nuclear reactor when a predetermined pressure value is reached including a closed tank which is provided with coolant fluid outlet and inlet pipes or conduits which extend respectively from the bottom and top of the tank, and which are connectable, via a normally closed self-actuated mechanical pressure relief valve, to a spray nozzle in the upper end of the pressurizer and to the vapor space within the upper portion of the pressurizer respectively. The tank is disposed vertically above the pressurizer and is partially filled with liquid coolant which is subcooled for the pressure existing in the pressurizer, while the four-way valve is set to open in response to the predetermined pressure being reached in the pressurizer.