MAIN STEAM RELIEVING SAFETY VALVE DEVICE

PURPOSE:To properly secure the gap between a disc socket of a valve element during normal operation and a guide for the valve element and prevent vibration etc., of the valve element by furnishing a groove stretching in the valve element moving direction at the inner surface of the guide and in the part where the valve element and guide are in pressure contact owing to a thermal deformation of a pressure piping. CONSTITUTION:A groove stretching in the moving direction of a valve element 2 of a main steam relieving safety device is furnished at the inner surface of a guide 12 for the valve element, and when a nuclear reactor is started, the gap between a disc socket 11 of valve element 2 and the guide 12 decreases due to temp. rise in the valve box 1. and at the same time, the body of safety valve will tumble due to difference in the thermal elongation between the main steam piping 16 and exhaust pipe 17, Even though the disc socket 11 is going to contact the guide 12, it will never happen because of provision of the groove in the guide 12. Accordingly there is no generation of a tumbling moment due to contact of the socket 11 with guide 12 to permit securing a gap between the disc socket 11 of the valve element 2 in normal operation and the guide.