Kinetic study of copper precipitates under VVER-type reactor conditions

Abstract

The copper-rich cluster evolution in the neutron-irradiated VVER steels is investigated beginning at the nucleation stage. For this, typical VVER-type reactor conditions are considered. The cluster dynamics approach is used for calculation of the density distribution of copper precipitates related to the number of Cu-atoms or radius, mean radius, volume content, number density of precipitates and the concentration of free Cu-atoms in dependence on the irradiation time. The results for time of one year are compared with the results of small angle neutron scattering experiments which were carried out on specimens irradiated at the surveillance positions of VVER reactors. It has revealed the intermediate type of the evolution kinetics between diffusion and interfacial kinetics limited regimes. The duration of the nucleation and deterministic stages is estimated. The coarsening stage does not occur.

Keywords:

• Neutron irradiation
• Microstructure
• Reactor pressure vessel steel
• Radiation defects
• Cluster dynamics

Acknowledgement

The authors would like to thank Mr. E. Müller from Research Center Rossendorf for his help with computer technique. One of the authors (A. Gokhman) was supported by the DAAD Foundation and is grateful for sponsorship.