Abstract: A nuclear reactor plant has a nuclear reactor vessel in a containment vessel. Air ducts, sump discharge lines, service water lines and other non-process non-critical lines extending through the wall of the containment vessel can be isolated passively (i.e., without instrumentation and control systems or power) should a postulated event which raises the atmospheric temperature within the containment vessel occur. The passive containment isolation system includes an isolation valve disposed in the non-process line and an actuator responsive to the atmospheric temperature within the containment vessel. The actuator is operatively connected with the isolation valve for closing the non-process line in response to the atmospheric temperature. The actuator is preferably disposed in or adjacent a containment sump at the bottom of the reactor vessel or adjacent the reactor vessel cavity where the temperature of the local atmosphere will most rapidly rise.

Abstract: A primary coolant system of a nuclear power plant for providing coolant to a reactor vessel, the primary coolant system comprises a primary loop for transferring heat away from the reactor vessel. An accumulator tank for containing water under a pressurized, gaseous atmosphere is attached to the primary loop via a coupling, which provides an outlet for the coolant from the accumulator tank to pass to the primary loop. A valve, which includes a pressure sensor that senses the pressure in the accumulator tank and opens or closes the coolant flow in the coupling in response to the sensed pressure, is attached to the coupling for sensing the pressure in the accumulator tank.

Abstract: A tank especially suited for nuclear applications is disclosed. The tank comprises a tank shell for protectively surrounding the liquid contained therein; an inlet positioned on the tank for passing a liquid into the tank; a sump positioned in an interior portion of the tank for forming a reservoir of the liquid; a sloped incline for resting the tank thereon and for creating a natural flow of the liquid toward the sump; a pump disposed adjacent the tank for pumping the liquid; and a pipe attached to the pump and extending into the sump for passing the liquid therethrough. The pump pumps the liquid in the sump through the pipe and into the pump for discharging the liquid out of the tank.