Development of ODS ferritic steels for fast reactor

高速炉用ODSフェライト鋼の開発

大塚 智史   ; 鵜飼 重治  ; 藤原 優行; 皆藤 威二 ; 成田 健; 酒瀬川 英雄   

Otsuka, Satoshi; Ukai, Shigeharu; Fujiwara, Masayuki; Kaito, Takeji; Narita, Takeshi; Sakasegawa, Hideo

JAEAでは、実用化段階でのNa高速炉の高燃焼度燃料被覆管用(250GWd/t, 250doa)に9CrODSマルテンサイト鋼(9CrODS鋼)の開発を進めている。これまでに9CrODS鋼の製造技術開発を行い、数百本レベルの被覆管試作を実施した。これら開発研究の結果、目標強度700C120MPa10,000hを有する被覆管材料の製造に成功している。近年、さらなる高温クリープ強度改善のための組織制御技術開発、及び大量生産技術開発及び環境効果データベース(中性子照射,腐食)の蓄積を進めている。さらに、MEXT「スーパーODSプロジェクト」のもと鉛ビスマス(LBE)冷却高速炉及び超臨界水(SCW)冷却高速炉被覆管用にODS鋼の改良を開始した。本発表では、JAEAにおける9CrODS鋼開発の現状、特に組織制御技術開発及び9CrODS鋼のLBE共存性評価結果について報告する。

Japan Atomic Energy Agency (JAEA) has gone ahead on with the research and development of the advanced type sodium (Na)-cooled fast reactors, and come to the conclusion that the high performance nuclear fuel resisting to high burn-up -250GWD/t: 250dpa- and high-temperature operation -700C- is indispensable for adequate economical operation. JAEA has developed a manufacturing process of the cladding tube made of 9CrODS martensitic steel (9CrODS), and accumulated knowledge by fabricating several hundred of the tube. These activities have led to the resounding success in establishing a fabrication process of the 9CrODS tube having the target creep strength of 700C120MPa (in hoop)10,000h. In recent years, our efforts have been made to develop a microstructure control technique that further improves the creep strength, a large scale manufacturing procedure, a database on environment effects including radiation damage and corrosion resistance, and so on. In addition, under the contribution to the Super ODS project sponsored by MEXT, the modification of the ODS steel has been started for the application to the high burn-up cladding tube of lead-bismuth eutectic (LBE)-cooled reactor and super critical pressurized water (SCW)-cooled reactor. In this presentation, we will report the current status on the 9CrODS development in JAEA, in particular the microstructure control procedure for high-temperature strength improvement as well as the compatibility of the 9CrODS steel with LBE.