Radiation embrittlement modelling for reactor pressure vessel steels: I. Brittle fracture toughness prediction

Modelling for the irradiation effect on brittle fracture toughness of react or pressure vessel (RPV) steel is performed on the basis of the probabilist ic model for fracture toughness prediction proposed by the authors earlier. The irradiation effect on parameters controlling plastic deformation and b rittle fracture of RPV steels is analyzed. The physical mechanisms are cons idered which control the cleavage microcrack nucleation for RPV steels in t he unirradiated and irradiated states and also in state after post-irradiat ion annealing. Prediction of the temperature dependence of brittle fracture toughness is performed as applied to irradiated 2.5Cr-Mo-V reactor pressur e vessel steel. Modelling of the fluence effect and the phosphorus and copp er content effect on brittle fracture toughness is carried out. It is shown that the probabilistic model based on a new formulation for brittle fractu re criterion allows the adequate modelling for the irradiation effect on fr acture toughness for RPV steel. Application of alternative models is discus sed for fracture toughness prediction for irradiated RPV steels. (C) 1999 E lsevier Science Ltd. All rights reserved.