低放射化フェライト鋼開発の最近の成果; 日米HFIR共同照射実験第4期計画及び関連研究の中間報告

Recent accomplishment for the development of reduced activation ferritic/martensitic steels; Interim report for HFIR phase 4 with results of relating activities

物質科学研究部; 核融合工学部(東海駐在)

Department of Materials Science; Department of Fusion Engineering Research (Tokai Site)

低放射化フェライト鋼F82H及び数種の類似鋼を対象に、ここ数年間に渡り照射挙動の評価を精力的に実施してきた。この結果、使用下限温度の明確化と照射による劣化への対策等を得ることを目指す高照射量実験について、(1)弾き出し損傷にして20dpaまで、延性脆性遷移温度(DBTT)の上昇への照射効果の評価を達成し、また、同位体調整したニッケルやホウ素の微量添加手法を用い、(2)DBTT上昇へのHe原子の助長効果についての実験的解析を進め、さらに、(3)高温高圧水中低速引張試験により、環境割れへの照射効果等の概要を得ることができた。加えて、照射後試験装置の開発や関連研究の進捗が得られた。本報告書は、これらの結果をまとめたものである。なお、得られた結果は、低放射化フェライト鋼が核融合炉への使用に対し高い適合性を持つことを示している。

Extensive efforts for evaluating the irradiation performances of a reduced activation ferritic/martensitic steel (RAF/M) of F82H* and other several RAF/Ms have been made in recent several years. They are, examinations of the effects of neutron irradiation on (1) Ductile to brittle transition temperature (DBTT) up to a damage level of 20 dpa to explore lower temperature limit, (2) Enhanced He effect on DBTT shift for Ni/B doped heats (isotopic tailoring method was used for B doping), (3) Susceptibility to environmentally assisted cracking by the slow strain rate tensile tests (SSRT) in a high temperature pressurized water and (4) Flow stress-plastic strain relation obtained by measuring the profile of the specimen during tensile testing, together with the activities of (5) the development of the test methods after neutron irradiation and (6) other supporting researches. Results are summarized in the present report. They clearly indicate the good applicability of RAF/Ms to fusion machines.