Synergistic effect of displacement damage and helium atoms on radiation hardening of F82H at TIARA facility

Ando, Masami; Wakai, Eiichi  ; Sawai, Tomotsugu; Tanigawa, Hiroyasu; Furuya, Kazuyuki; Jitsukawa, Shiro; Takeuchi, Hiroshi; Oka, Keiichiro*; Onuki, Somei*; Koyama, Akira*

One of the most crucial issues on R&D of reduced activation ferritic/martensitic steels is the effect of helium on the degradation of fracture toughness. The synergistic effects of displacement damage and helium on F82H steel can be partially simulated by martensitic steels doped with B or Ni in a mixed spectrum fission reactor. However, the control of helium production rate is difficult and the chemical effects of B or Ni doping on mechanical property are not small. Therefore, multi-ion irradiation method is the most convenient and accurate method to simulate various irradiation conditions. Moreover, the effects of helium on irradiation hardening behavior can be examined by combining ion-irradiation with ultra micro-indentation technique. The purpose of this study is to examine the extra component of radiation hardening due to implanted helium in F82H. The extra component of irradiation hardening due to helium was hardly detected in the dual-beam irradiation. Therefore, the effect on irradiation hardening below 630K of helium (500 appm) was very small.