Investigation of the effects of irradiation on corrosive environments using in-situ electrochemical measurements during -ray irradiation

Sato, Tomonori  ; Ueno, Fumiyoshi  

The structural materials used in Fukushima-Daiichi Nuclear Power Plant are exposed to the water containing some impurities, e.g., seawater components, under irradiation. The hydrogen peroxide and hydrogen generated by water radiolysis under irradiation condition. It was reported that -ray irradiation enhanced the corrosion of carbon steel by the weight loss measurements in the immersion test of carbon steel under irradiation. The in-situ measurement of the electrochemical parameter during irradiation is one of the most effective approaches to investigate the effects of irradiation on the corrosion. In this study, to investigate the effects of -ray irradiation on the corrosive condition and corrosion phenomena, the in-situ electrochemical measurement method during irradiation was constructed, and the cyclic voltammetry (CV) was performed in the diluted artificial seawater under -ray irradiation conditions. The dose rate of -ray was 3.3 kGy/h, and the temperature was fixed at 50 degrees centigrade. Obtained major results are in follows;(1) The in-situ electrochemical measurements were successfully performed in this study. (2) The diffusion limiting current in the cathodic region decreased just after the start of irradiation. And then the cathodic current increased. This tendency indicated that the dissolved oxygen was consumed rapidly by the irradiation. The consumed dissolved oxygen contributed to the generation of hydrogen peroxide. (3) The cathodic current under irradiation was 20 percents larger than that before irradiation. (4) The anodic current increased just after the start of irradiation by the generation of hydrogen and hydrogen peroxide.