Effect of Sd seismic loading on the allowable flaw sizes in acceptance standards of reactor pressure vessels

Abstract

The Rules on Fitness-For-Service for Nuclear Power Plants of the Japan Society of Mechanical Engineers (the Rules on FFS) specify the acceptance standard, the crack size that is not necessary for evaluation, of reactor pressure vessels and pipes. When determining the acceptance standard, the crack growth due to the S₁ seismic loading assumed during the plant service was evaluated, and it was confirmed that the effect of the earthquake on structural integrity was negligible. However, since the seismic load in the latest regulatory standards was changed from S₁ to Sd earthquake, the crack growth behavior due to Sd earthquake was examined, and it was confirmed that the effect of the Sd earthquake on the structural integrity was as small as the S₁ earthquake.