AUTOCLAVE STUDIES OF THE DURABILITY OF SPECIMENS SIMULATING PIPE-COLLECTOR JOINTS IN STEAM GENERATORS OF NUCLEAR POWER PLANTS

摘要

We performed studies of welded-pressed (by explosion) joints of pipes made of 08Kh18N10T and 08Kh14MF steels with nozzles made of 10GN2MFA steel in order to simulate the operation of PGV-1000 steam generators. We established that the fatigue limit based on 1 centre dot 10~5 cycles is greater for the joints of pipes made of 08Kh14MF steel in tests in air. On the autoclave tests in reactor boron-treated water in the primary contour of a nuclear power plant at a temperature of 350 deg C, the endurance of the joints of pipes made of 08Kh14MF steel was 39 percent less that that for the joints made of 08Kh18N10T steel. All specimens failed at the lower ends of joints that were in the water phase of the working medium rather than in the steam one, which corresponds to the service conditions of the output "cold" collector of a steam generator. We concluded that cracks are initiated due to fretting corrosion and grow by the mechanism of corrosion-cyclic cracking of the steels of pipes.