Fracture toughness evaluation on neutron irradiation embrittlement for reactor pressure vessel steels

Onizawa, Kunio ; Suzuki, Masahide

To assure the structural integrity of reactor pressure vessel (RPV) throughout its operational life, fracture toughness of the steel after neutron irradiation must be determined. In this report the investigation on the master curve approach using Charpy-size specimens is presented for the precise evaluation of fracture toughness on irradiation embrittlement. Using some Japanese A533B-1 steels, fracture toughness tests in the transition range were performed varying specimen thickness. Charpy-size specimens were also irradiated at Japan Materials Testing Reactor. Applying the master curve method and JEAC method as well, the specimen size effect, temperature dependence and the lower bound were evaluated. The shifts of reference temperature of fracture toughness and Charpy transition temperature due to neutron irradiation were also compared and found to be almost equivalent.