ネプツニウム237を含む硝酸水溶液中のステンレス鋼腐食に与える濃度と温度の影響

Effect of concentration and temperature on corrosion of stainless steel in nitric acid solution containing neptunium-237

入澤 恵理子 ; 山下 直輝; 加藤 千明   ; 佐野 成人

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

原子力発電後の使用済燃料再処理施設では、燃料由来の金属イオンを含む硝酸水溶液によるステンレス鋼製機器の粒界腐食が問題となる。放射性元素であるネプツニウムは腐食への寄与が高いとされるが、取り扱いが難しいために体系的に腐食評価が行われた事例が少ない。そこで、ネプツニウム237を含む硝酸水溶液中のステンレス鋼の腐食速度に与える溶液温度やネプツニウムイオン濃度の影響を浸漬試験や分極測定により評価した。

In spent fuel reprocessing plants after nuclear power generation, intergranular corrosion of stainless steel components due to nitric acid solution containing metal ions derived from fuel is a problem. Although neptunium, a radioactive element, is considered to have a high contribution to corrosion, there have been few cases of systematic corrosion evaluations due to the difficulty of handling it. Therefore, the effects of solution temperature and neptunium ion concentration on the corrosion rate of stainless steel in nitric acid solution containing neptunium-237 were evaluated by immersion test and polarization measurement.