Cooling system for primary containment vessel in nuclear power plant and component for use in said cooling system

In a cooling water system for a primary containment vessel in a nuclear power plant which system includes a gas vent which extends from a heat exchanger of a condenser-type heat removal system into a suppression pool to be communicated with the water in the suppression pool;

• the improvement wherein means for restraining upward movement of a vent fluid is provided on a portion of said gas vent disposed in the suppression pool to extend horizontally to an extent greater than a flow area of said gas vent, said restraining means including communication holes communicated with the water of the suppression pool and disposed below a level where a maximum gas-to-liquid contact area is formed, and said communication holes being distributed over a range larger than the flow area of said gas vent, and in which said restraining means comprises horizontal pipes connected to and communicated with said gas vent in a plurality of directions, each of said pipes having a closed distal end, and each of said pipes having openings which are in free communication with the water of the suppression pool and are disposed only below a horizontal plane in which axes of said pipes lie.