Technical development for IASCC irradiation experiments at the JMTR

Shibata, Akira ; Nakano, Junichi; Omi, Masao; Kawamata, Kazuo; Saito, Takashi; Hayashi, Koji; Saito, Junichi ; Nakagawa, Tetsuya; Tsukada, Takashi 

Irradiation assisted stress corrosion cracking (IASCC) is considered to be one of the key issues in the aged Light Water Reactors. To simulate IASCC behavior by the in-pile or post-irradiation experiment, it is necessary to irradiate specimens up to a neutron fluence that is higher than the so-called IASCC threshold fluence. There are, however, some technical hurdles to be overcome for the experiments. The techniques assembling pre-irradiated specimens into a in-pile test capsule in a hot cell and the eveluation of material integrity of the capsule during a long term irradiation are necessary. To evaluate material integrity on capsules during a long term irradiation, tensile test and SSRT using specimens which was previously irradiated to 1.03.910 n/m were performed. In this paper, technical developments required for IASCC test, e.g. the development of assembling techniques for IASCC capsules and the evaluation of stainless steels which dosed high-fluence neutron were described.