Irradiation creep behavior of reduced activation ferritic/martensitic steel irradiated in HFIR

The irradiation creep behavior of F82H and several JLF-1 steels has been measured at 573 and 773 K up to 5 dpa using pressurized creep tubes irradiated in HFIR. These tubes were pressurized with high-purity helium to hoop stress levels of 0 to 400 MPa at the irradiation temperature. The results for F82H and JLF-1 with hoop stress of 400 MPa showed small creep strains (<0.25%) after irradiation at 573 K. The irradiation creep strain at 573 K in these steels is linearly dependent on the applied stress at stress levels below 250 MPa. However, at higher hoop stress levels, the creep strain is nonlinear. At 773 K, the irradiation creep strain of F82H is linearly dependent on the applied hoop stress level below 100 MPa. At higher stress levels, the creep strain increased strongly. The creep compliance co-efficient for F82H and JLF-1 is consistent with the values obtained for other steels. These data contribute to the materials database for ITER test blanket design work. (author)