Investigation on surveillance specimen exclusion for heat affected zone materials of reactor pressure vessel steels, 5; Evaluation of the susceptibility to neutron irradiation embrittlement

Tobita, Toru; Katsuyama, Jinya; Fuse, Masaharu; Otsu, Takuyo*; Onizawa, Kunio

no journal, , 

In order to obtain the technical basis to judge the necessity of surveillance specimens from heat-affected zone (HAZ) materials of reactor pressure vessel (RPV) steels, the neutron irradiation program for base metals and simulated HAZ materials was performed at JRR-3. The materials used were fabricated as typical RPV steels varying impurity levels. It was indicated that the fracture toughness of simulated HAZ materials was equivalent to or better than that of base metal before neutron irradiation. Concerning the effects of impurities and metallographic structures on the mechanical properties the neutron irradiation embrittlement susceptibility of simulated HAZ materials was compared with that of base metal. The irradiation embrittlement as well as irradiation hardening of simulated HAZ materials was evaluated to be roughly equivalent to those of base metal. However, it was suggested that there may be a local region in HAZ susceptible more to irradiation embrittlement than base metal.