Effect of oxidizing metallic ions on corrosion of stainless steel during concentration process simulating High-level Activity Liquid Waste (HALW) concentrator

高レベル放射性廃液濃縮缶を模擬した濃縮工程中でのステンレス鋼腐食に与える高酸化性金属イオンの効果

入澤 恵理子 ; 加藤 千明   ; 鴨志田 美智雄*; 袴塚 保之*; 上野 文義  ; 山本 正弘 

Irisawa, Eriko; Kato, Chiaki; Kamoshida, Michio*; Hakamatsuka, Yasuyuki*; Ueno, Fumiyoshi; Yamamoto, Masahiro

In the PUREX method for reprocessing of nuclear spent fuels, the HNO media with high concentration is heated up to boiling point to dissolve fuels. The process solutions containing oxidizing metallic ions dissolved from spent fuels are very corrosive because of these high oxidizing activities, and the corrosion problem have appeared on the stainless steel concentrators and evaporators such as the intergranular corrosion of stainless steel. We focused how the change of solution composition and temperature on the corrosion rate of stainless steel under the operation condition of High-level Active Liquid West concentrator of reprocessing plant in Japan. The corrosion immersion tests and the electrochemical measurements were performed using R-SUS304ULC as stainless steel test samples and the HNO solutions containing following oxidizing metallic ions. The corrosion rate increased caused by increasing of the HNO and metallic ions concentration. The cathodic polarization curves showed that the current density increased with increasing of the concentration of HNO and metallic ions. Moreover, the results showed that the contribution of Ru and V which can maintain the acceleration effect on the corrosion because of high re-oxidation rate after the reductant with the corrosion reaction in the solution.