Prediction of radiation embrittlement for highly irradiated reactor vessel steels, 5; Auger electron microprobe analysis on grain-boundary chemistry

Nishiyama, Yutaka ; Yamaguchi, Masatake   ; Onizawa, Kunio ; Matsuzawa, Hiroshi*

In order to predict the degree of irradiation embrittlement of reactor pressure vessel (RPV) steels exposed to high neutron fluences, it is necessary to study on the likelihood of intergranular embrittlement, which decreases the grain boundary strength due to the segregation of impurities such as phosphorus at grain-boundaries and promotes the increase in ductile-brittle transition temperature (DBTT). Using highly irradiated RPV steel samples, it was found through scanning Auger microprobe analyses that the irradiation-induced P segregation increased with increasing neutron fluence and bulk levels of P. In addition, results from the comparison between this results and DBTT, and theoretical analysis on the embrittlement mechanism by first principle calculation are presented.