Influence of cascade micropores on diffusion fluxes of point defects in reactor vessels materials

The main mechanism determining radiation embrittlement of the materials of reactor vessels are considered to be a change in the cohesive strength of t he,grain boundaries resulting from the segregation of surface-active impuri ties (mainly phosphorous), hardening of the material by precipitations of a second phase, segregation of impurities onto interphase surfaces of the pr ecipitate-matrix interface and an associated increase in the hardening effe ct of the radiation precipitations. The materials of reactor vessels are ir radiated at a temperature of 250-300 degrees C which is insufficiently high for the thermal activation of diffusion processes. When describing the pro cess of an accelerated diffusion of copper and phosphorous atoms by irradia tion, a model has so far normally been used which neglects the cascade mech anism for generating defects and also the formation and evolution of point defect complexes, individual studies taking account of the reduction in the efficiency of generating point defects in cascades due to the formation of micropores contain certain deficiencies. The present work is devoted tl? d eveloping and analyzing a satisfactory model of radiation damage which is t o a considerable extent free of these deficiencies.