A kinetics study of vacancy cluster evolution under VVER-type reactor condition

The vacancy clusters (VC) evolution in the neutron-irradiated VVER-type reactor pressure vessel steels is investigated, beginning at the nucleation stage and finishing in the coarsening stage. For this, characteristic VVER-type reactor conditions are considered. VC evolution in the nucleation stage is analysed on the basis of the computer simulation data. During the deterministic and the coarsening stage, elastic interaction between iron matrix and VC is accounted, that provides the stability of the peak of the size distribution function under the condition of increasing neutron fluence in correspondence to the experiments. The results are compared with the results of SANS experiments which were carried out on specimens irradiated at surveillance positions of VVER reactors. The presented approach may be used for analyses of the small inhomogeneities (about 1 nm) in the irradiated damage structure of the VVER-type steels.