In-sodium test on MONJU 22-in isolation valves (II); Long-Term performance test

not registered; Aoki, Tadao; not registered

In sodium test on the two models of 22-in isolation valves to be applied to the secondary cooling system of MONJU was carried out. The results of initial performance test was reported in the perious paper PNC SN941 79-57. Present paper describes the long-term performance of the same valve models (about 10,000 hrs for the butterfly valve and about 15,000 hrs for the gate valve) in sodium at 400 C. Results obtained are as follows: (1)The leak test done in sodium and the in-water leak test done after dismantling showed that the butterfly valve satisfies the allowable leak rate of SG isolation valve. The values of allowable leak rates (provisional) are 1.5/sec for ACCS operation and 10 /min for sodium-water reaction in SG. (2)The continuous actuation tests in sodium at 400 C showed that both valves satisfy the allowable actuating time of 60 sec. (3)A test was carried out to assure the integrity of freeze seal under possible high ambient temperature on the failure of air conditioning facility and it was found that the shaft seal function is maintained under the temperature as high as about 80 C. (4)Reliable function of sodium leak detector was demonstrated. (5)Replacement of shaft real part may be needed on the maintenance campaign of MONJU. An effective method using oil-pressure jack is proposed for this replacement.