RADIATION EFFECTS ON GRAIN-BOUNDARY CHEMISTRY RELEVANT TO STRESS-CORROSION CRACKING OF STAINLESS-STEELS

Calculated grain boundary microchemistries are related to the potential for irradiation-assisted stress corrosion cracking (IASCC) for the proposed International Thermonuclear Experimental Reactor (ITER) conditions of irradiation temperature and dose. Radiation-induced segregation predictions are calibrated to measured segregation at temperatures above 250-degrees-C and are then used to extrapolate to expected segregation behavior for ITER temperatures of 50 to 100-degrees-C. Chromium depletion and impurity enrichment is predicted to occur for ITER conditions. Although the predicted segregation is less than that observed for light-water reactor conditions (LWR) experience with cracking in nonirradiation environments suggest that cracking may still occur because of possible differences in stress and environment. Experiments are required to verify the predicted ITER microchemistries and to demonstrate that the microchemistries will not promote cracking for specific ITER conditions.