ネプツニウム-237を含む硝酸水溶液中でのステンレス鋼の分極特性と腐食速度の評価

Polarization characteristics and evaluation of corrosion rate of stainless steel in nitric acid solution containing Np

入澤 恵理子 ; 加藤 千明   ; 山下 直輝; 佐野 成人

Irisawa, Eriko; Kato, Chiaki; Yamashita, Naoki; Sano, Naruto

使用済核燃料再処理溶液施設でのステンレス鋼の腐食評価として、放射性核種であるNpを含む硝酸水溶液中でのステンレス鋼R-SUS304ULC鋼の浸漬腐食試験と分極測定を行った。328K以上の温度では硝酸水溶液中よりも高い腐食電位を示し、過不動態域近傍となることがわかった。また、浸漬腐食試験により腐食量と分極抵抗との比較から換算係数として=0.018V0.025Vの値を取得し、電気化学測定からの腐食量算出が可能であるかを検討した。

In order to evaluate the corrosion of stainless steels used in spent nuclear fuel reprocessing facilities, the immersion corrosion tests and polarization measurements were performed using R-SUS304ULC stainless steel in nitric acid solution containing a kind of radionuclides, Np. At temperatures above 328 K, the corrosion potential was higher than that in nitric acid solution and was near the transpassive region. From the comparison between the corrosion amount calculated by the immersion corrosion tests and the polarization resistance, the values of =0.018-0.025 V were obtained as a conversion factor, and the possibility of calculating the corrosion amount from the electrochemical measurement was examined.