Compatibility of FBR structural materials with supercritical carbon dioxide

超臨界CO中における高速炉構造材料の耐食性

古川 智弘  ; 稲垣 嘉之; 有冨 正憲*

Furukawa, Tomohiro; Inagaki, Yoshiyuki; Aritomi, Masanori*

高速炉構造材料候補材である12Cr鋼と316FR鋼について、20MPa, 400600Cの高温超臨界CO中にて8000時間までの耐食性評価試験を実施した。その結果、両鋼腐食挙動は大きく異なっており、12Cr鋼では時間の経過とともに重量増加挙動を呈する放物線型腐食挙動を呈したのに対し、316FR鋼では重量増加挙動はごくわずか(温度・時間依存性なし)であり良好な耐食性を呈した。なお、12Cr鋼ではブレイクアウェイ酸化は観察されなかった。これらの金属組織観察結果を踏まえ、プラント予備設計に必要なこれら候補材の超臨界CO中での腐食評価式を作成した。

Compatibility of the FBR candidate materials, 12Cr-steel and 316FR, with supercritical CO pressurized at 20 MPa for up to 8000 hours at 400-600 C has been investigated. Corrosion due to the high temperature oxidation was measured in both steels. Results showed that the behavior differed greatly. For 12Cr-steel, weight gain showed parabolic growth as exposure time increased at each temperature, and no breakaway oxidation was observed. The specimens were covered by two successive oxide layers. For 316FR, the weight gain was significantly lower than that of 12Cr-steel, and good resistance against corrosion was observed. No dependency of temperature or immersed time on weight gain was observed. Based on the metallurgical examination, corrosion formula in supercritical CO has been shown for the candidate materials for provisional design.