Isolation valve disposed to cooling system for FBR type reactor

Purpose: To obtain an isolation valve with simple structure thus less possibility of failures, requiring short period of time from the occurrence of troubles to the valve actuation and having high reliability. Constitution: If sodium-water reaction should be caused by pipeway destruction accidents in a steam generator, high pressure generated due to the reaction propagates through sodium pipeways, which breaks the breaking plates and the high pressure is introduced by way of a releasing pipe to a pressure receiving chamber of a pressure accumulation cylinder. Then, the high pressure urges the piston to compress the compressible fluid in the pressure accumulation chamber. The pressure in the pressure accumulation chamber causes the release valve to open by way of the pressure pipe, to escape the pressure in a second cylinder chamber into atmosphere, etc., as well as introduce the pressure into a first cylinder to urge the piston and the valve rod to cause the valve closing operation. In this way, the isolation valve is actuated by utilizing the high pressure resulted upon sodium-water reaction to shorten the time required up to the closure of the valve. (Kawakami, Y.)