CHALLENGES AND RECENT PROGRESS IN CORROSION AND STRESS COROSION CRACKING OF ALLOYS FOR SUPERCRITICAL WATER REACTOR CORE COMPONENTS

摘要

The Supercritical Water Cooled Reactor (SCWR) is one of the most promising Generation 1V nuclear reactor designs. Reactor operating conditions call for a core coolant temperature between 280 and 620℃ at a pressure of 25 Mpa and neutron damage levels of 15 dpa (thermal reactor design) and 100 dpa (fast reactor design). In the hotter regions of the core, irradiation-induced changes in microstructure (swelling, radiation induced segregation (RIS), hardening, phase stability) and mechanical properties (strength, thermal and irradiation induced creep, fatigue) are major concerns. Throughout the core, corrosion, stress corrosion cracking and the effects of irradiation on them are the most overriding issues. This paper presents a preliminary study of the effect of proton irradiation on the microstructure on two stainless steels, alloys 304L and 316L, and one nickel-base alloy, Inconel 690, and its effect on stress corrosion cracking in 500℃ supercritical water. Results show a significant increase of the cracking susceptibility of those alloys and a cracking morphology slightly different than that observed in BWR and PWR environment.