Influence evaluation of corrosion on long-term integrity of spent fuel assembly component materials exposed to unusual corrosive environment at unit 1-4 spent fuel pools of Fukushima Dai-ichi Nuclear Power Stations

Fukushima Project Team, Oarai Research and Development Center; Fukushima Fuels and Materials Department, Oarai Research and Development Center

In this study, a screening study on corrosion phenomena and a preliminary investigation for an evaluation method on long-term integrity of FAs experienced unusual corrosive environment were carried out in views of fundamental features of corrosion. The screening study have led to the following two features of FAs from the viewpoint of the integrity as important phenomena to be further investigated; "fission product confinement of cladding tube" and "structural integrity of FA". In terms of "fission product confinement of cladding tube", it was shown experimentally that influence of the exposure to an unusual corrosive environment was low. On the other hand, in terms of "structural integrity of FA", a concept of experimental methodology for predicting long-term corrosion behavior was preliminary studied for preferentially selected FA local parts composed of different metals.