液体鉛ビスマス合金流動場で自己修復する耐食性構造材料～原子力のゴミをエネルギーに変える加速器駆動型未臨界炉の実現に向けて前進～

2026-03-03 東京科学大学

東京科学大学と日本原子力研究開発機構（JAEA）の研究グループは、加速器駆動型未臨界炉（ADS）の核破砕ターゲットを模擬した液体鉛ビスマス共晶合金（LBE）流動環境下で、FeCrAl合金の高い耐食性と自己修復機能を実証した。大型流動ループ「OLLOCHI」を用い、約450℃で最大4,000時間の長期腐食試験を実施した結果、合金表面にCr・Fe酸化層とAlリッチ酸化層からなる多層保護被膜が形成され、腐食を効果的に抑制することを確認。さらに被膜を人工的に剥離しても、追加浸漬により自発的に再形成されることを明らかにした。本成果は、高レベル放射性廃棄物の核変換とゼロカーボン電力供給を両立するADS実用化に向け、構造材料の信頼性向上に貢献するものである。

図1.液体LBEターゲット式の加速器駆動型未臨界炉（ADS）の概要

＜関連情報＞

流動鉛ビスマス共晶溶液中で4000時間曝露したFeCrAl合金の人工研磨表面における保護酸化物層の再形成 Reformation of protective oxide layers on artificially abraded surfaces of FeCrAl alloy during 4000 h exposure in flowing lead-bismuth eutectic

Masatoshi KONDO, Yoshiki KITAMURA, Atsushi KAWARAI, Shigeru SAITO, Hironari OBAYASHI
Corrosion Science Available online: 21 January 2026
DOI:https://doi.org/10.1016/j.corsci.2026.113646

Highlights

Corrosion behavior of FeCrAl alloy was studied in flowing LBE at 723 K for 4000 h.
Multiple Fe-, Cr-, and Al-rich oxide sub-layers formed in situ and suppressed corrosion.
Multiple oxide layers re-formed in situ in flowing LBE after removal by abrasion.
In-situ formed oxide layers exhibited high shear adhesion strength in shear direction.
Pre-formed α-Al₂O₃ layer remained adherent after 2000 h exposure to flowing LBE.

Abstract

The corrosion resistance of FeCrAl alloy APMT (Fe-21Cr-5Al-3Mo) in flowing lead-bismuth eutectic (LBE) was investigated by corrosion tests performed at 723 K using a non-isothermal forced convection loop. The oxygen concentration in flowing LBE was controlled at 1 × 10⁻⁶ wt%. No severe corrosion or erosion was detected on the specimens exposed to flowing LBE for 2000 h and 4000 h. Multiple oxide layers consisting of Fe-rich, Cr-rich and Al-rich sub-layers were formed in situ on the surface of APMT during the corrosion tests, which effectively suppressed corrosion and erosion. The oxide layers were intentionally removed by gentle abrasion prior to re-immersion and the specimens were then re-immersed in flowing LBE for an additional 2000 h. The oxide layers were spontaneously re-formed in situ on the abraded surface. This behavior indicates a self-healing capability. The results of micro-scratch tests indicated that the in-situ formed multiple oxide layers exhibited high adhesion strength in the shear direction after the 2000 h corrosion test. The α-Al₂O₃ layer pre-formed by oxidation in air at 1373 K remained adherent to the APMT specimen during exposure to flowing LBE for 2000 h. The adhesion strength of the α-Al₂O₃ layer in the shear direction was not degraded after the corrosion test.