Electrochemical corrosion tests for core materials utilized in BWR under conditions containing seawater

Shizukawa, Yuta ; Sekio, Yoshihiro  ; Sato, Isamu*; Maeda, Koji  

Electrochemical corrosion behavior under salt water in a type 304L stainless steel used to a part of BWR core materials was investigated to evaluate the possibility of crevice corrosion occurrence for the fuel assemblies which experienced seawater exposure in Fukushima Daiichi Nuclear Power Plant (1F) accident. Especially, focusing on the upper end plug part having the 304L SS crevice structure, measurement of repassivation potential for crevice corrosion () were carried out using the crevice test pieces fabricated by 304L SS plates. From the results, was lower than the spontaneous potential () when the conditions of 2500 ppm chloride ion concentration at over 50 C or that of 2500 ppm at over 80 C, which are included in the SFP water quality conditions. Therefore, in the 304L SS parts of the 1F fuel assemblies that experienced seawater exposure, there is a possibility of crevice corrosion occurrence.