Microstructural evolution of SINQ irradiated austenitic stainless steels

A type 316 stainless steel 316F and Ti-modified type 316 stainless steel JPCA irradiated in SINQ were examined using transmission electron microscopy. Estimated irradiation temperatures for two 316F specimens were 250 and 300 °C and that for the JPCA specimen was 255 °C. Irradiation damage of these specimens is calculated to be about 10 dpa. In the 316F specimen irradiated at 300 °C, Frank loops up to 30 nm were observed and larger perfect loops up to 50 nm were observed. Numerous defect clusters smaller than 5 nm were also observed. Stacking fault tetrahedra up to 2 nm were also observed. Dislocation loops up to 20 nm were observed in the JPCA specimen. They are smaller than those observed in 316F and it is reasonable considering the lower irradiation temperature of the JPCA specimen and lower dislocation bias expected in JPCA.