Nano-meso Structures and Ring-tensile Properties of Neutron-irradiated ODS Steels

Yamashita, Shinichiro   ; Yoshitake, Tsunemitsu ; Akasaka, Naoaki; Ukai, Shigeharu  ; Onuki, Somei

Three ODS steel claddings, one martensitic phase and two ferritic ones in initial structures, were neutron-irradiated in the experimental fast reactor, JOYO, and those nano-meso structural evolutions during irradiations and those ring-tensile behaviors at as close conditions as it should be in service were evaluated. As for the structural features, no significant structural changes in macro scale such as grain morphology and dislocation structure were recognizable, but those in nano scale such as carbide and oxide dispersoid emerged in all neutron-irradiated ODS claddings. With respect to the ring-tensile properties, on the other hand, a manifested variation of an irradiation temperature dependence among all the ODS claddings was revealed, reflecting the each microstructural evolution of ODS claddings during neutron irradiation.