Experimental studies on prevention of leakage from valve gland packings in nuclear power plants, (1)

The prevention of the leak to outside from the valves used for nuclear power stations is an important problem for heightening the reliability and capacity ratio of the plant operation. For the purpose of establishing the proper maintenance method for packings in valve glands under the temperature and pressure conditions of PWRs, this research was carried out by the cooperation of the Central Research Institute of Electric Power Industry and Toa Valve Co., Ltd. Accelerated leak experiment, the endurance test by more than 1500 hours operation and the experiment by changing the filling density of packings were carried out, using a simulation setup of a 3B valve in a PWR RCS line and six kinds of packings. Based on the results of these experiments, the method of proper maintenance of valve glands in actual plants was proposed. This report is the first report, in which the results of the experiment when the valve rod was stopped for 20 hours and operated 500 times in about 7.2 hours under the design condition of a RCS line, that is, 300 deg C, 175 kgf/cm2 G, boric acid concentration 1500 ppm, are summarized. (Kako, I.)