IASCC INITIATION TEST OF NEUTRON IRRADIATED TYPE 316L STAINLESS STEEL IN SIMULATED BWR CONDITION TO EVALUATE THRESHOLD STRESS

摘要

Effect of stress on IASCC susceptibility was examinedwith Type 316L SS tube materials neutron irradiated up to1 × 10~(26) n/m2 (E>1 MeV). The constant load test insimulated BWR water was conducted at several stresslevels from 60 to 100% of the irradiated 0.2% proof stress.Under oxidizing conditions (32 ppm DO at the inlet),intergranular fracture was observed on the surface of Cringspecimens at relatively high stress levels. From thetest results, the IASCC threshold stress was estimated fromthe minimum initiation lifetime using an exponentialdistribution model. Based on these results, an apparentstress limit for IASCC of the test material was estimated atabout 80% of the irradiated 0.2% proof stress.