報告書番号

T98059

タイトル（和文）

304ステンレス鋼のSCC特性に及ぼす中性子照射効果 -高照射量領域における熱鋭敏化材のSCC挙動-

タイトル（英文）

Neutron irradiation effects on SCC behavior of irradiated thermally-sensitized type 304 stainless steels

概要 （図表や脚注は「報告書全文」に掲載しております）

高炭素304ステンレス鋼（商用純度）の熱鋭敏化材および溶体化材について、軽水炉温度（290℃）で4x1022－3x1025n/m2、JMTR炉水温度（50℃）で1x1025－1x1026n/m2の中性子照射を行った。その後溶存酸素濃度 8、0.2、 0.001ppm の高温高圧水中でSSRT試験を行った。主な結果は以下の通り。軽水炉温度で照射した熱鋭敏化材の粒界割れ破面率は、中性子照射量1x1024n/m2以下で照射量の増加と共に増加する傾向を示し、さらに照射の進んだ3x1025 n/m2では未照射材の破面率より低下した（溶存酸素濃度0.2ppm）。溶体化材は1x1024 n/m2以下ではSCC感受性を示さず、3x1025 n/m2照射で感受性が認められた。JMTR炉水温度照射の場合、熱鋭敏化材の破面率は未照射材より低下し、溶体化材の破面率は照射量とともに増加する傾向を示した。

概要 （英文）

Thermally-sensitized and solution annealed commercial purity high carbon type 304 stainless steels were irradiated in Japan Material Testing Reactor (JMTR) at a LWR temperature of ~ 290 C to a fluence range from 4 x 1022 to 3 x 1025 n/m2 and at the temperature of JMTR coolant (~ 50 C) to a fluence range from 1 x 1025 to 1 x 1026 n/m2. Irradiated materials were examined by Slow Strain Rate Tensile (SSRT) test in three dissolved oxygen conditions (8, 0.2, 0.001 ppm DO). Main results were as follows; In the case of materials irradiated at LWR temperature, %IGSCC tested in 0.2 ppm DO increased with neutron fluence for thermally-sensitized materials (T.S.) irradiated to a neutron fluence less than 1 x 1024 n/m2 . However %IGSCC of T.S. with a fluence of 3 x 1025 n/m2 decreased clearly to a value less than that of unirradiated T.S.. On the other hand, no IASCC susceptibility was observed for solution annealed materials (S.A.) irradiated to a fluence less than 1 x 1024 n/m2 , but IASCC susceptibility was observed for S.A. irradiated to 3 x 1025 n/m2 . In the case of materials irradiated at JMTR coolant temperature, %IGSCC of T.S. tested in 0.2 ppm DO was smaller than that of unirradiated S.A.. %IGSCC of S.A. increased with neutron fluence .

報告者

キーワード