SCC Properties of Candidate Alloys for SCWR Core Components

Slow strain rate tests (SSRTs) were conducted, assuming the core coolant conditions of a supercritical water-cooled reactor (SCWR). Candidate alloys were chosen from austenitic stainless steels (SS), nickel base alloys, ferritic SSs, and titanium base alloys, referring to other industrial systems such as light water reactors, fossil power plants and waste processing systems. Austenitic SSs and Ni base alloys exhibited a considerable number of small side cracks in SCW even though they did not propagate to the notable SCC mode. Cross-sectional examination and the SSRTs in an Ar gas environment suggested the effect of creep deformation on side crack formation. Ferritic SS did not show SCC in sub-critical and supercritical water, while Ti base alloy exhibited transgranular (TG) SCC at 550 deg C and not at 290 deg C. (authors) deg.