Prediction and extension of lifetime of reactor pressure vessel, 1; Irradiation-induced precipitate G-phase NiSiMn

Matsukawa, Yoshitaka*; Watanabe, Daiki*; Tsurekawa, Sadahiro*; Abad, N. M.*; Muta, Hiroaki*; Yoshida, Kenta*; Kasada, Ryuta*; Yamaguchi, Masatake   ; Kumano, Hideki*; Endo, Minako*

It is now generally believed that when a light water reactor is operated for nearly 80 years, Ni-Si-Mn ternary intermetallic compounds such as the G phase and the phase precipitate in the pressure vessel steel, which contribute to irradiation embrittlement. We have started a basic study focusing on the relationship between these compounds and diffusion coefficients. In order to investigate the characteristics of interdiffusion at the precipitate/matrix interface of pressure vessel steels, bulk materials of the compounds were prepared by arc melting and bonded to bulk materials of pure iron to produce so-called diffusion pairs. In this report, we describe our findings for the G phase.