還元性の模擬アルカリ性地下水環境中での炭素鋼のSCC感受性

SCC susceptibility of carbon steel in simulated anaerobic alkaline ground-water environments

清水 孝介*; 井上 博之*; 谷口 直樹 ; 坂巻 景子 ; 立川 博一*

Shimizu, Kosuke*; Inoue, Hiroyuki*; Taniguchi, Naoki; Sakamaki, Keiko; Tachikawa, Hirokazu*

炭素鋼製HLWオーバーパックの、処分環境での超長期における健全性を保証するには、還元性の地下水環境中での炭素鋼のSCC感受性への溶液pHの影響を検討しておかなければならない。本研究では、pHを8から13に調製しかつArガスで脱気したNaHCO/NaCO水溶液中で、各pHでの水素発生平衡電位ならびにその近傍の電位での炭素鋼のSCC感受性を低速度歪み試験(SSRT)で測定した。SCC感受性はpH 9ならびに13近傍で極小となり、pH 11近傍で極大となった。

The effect of solution pH to the SCC susceptibility of carbon-steel (CS) in an anaerobic ground water must be investigated to guarantees the soundness of the CS HLW overpack for ultra-long term. For the present study, the SCC susceptibility of CS at and near the reversible hydrogen evolution potentials at each solution pH was evaluated by the slow strain rate test (SSRT); as for the test solution, NaHCO/NaCO solutions whose pH were adjusted 8 to 13 and purged with Ar gas were used. The SCC susceptibility became minimum at pH near 9 and 13 as well as reached maximum at pH near 11.