German and Russian Irradiated Reactor Pressure Vessel Steels from PAS Point of View

This paper presents a comparison of commercially used German and Russian reactor pressure vessel steels from the positron annihilation spectroscopy point of view, having in mind knowledge obtained also from other techniques from the last decades. The second generation of Russian reactor pressure vessel steels seems to be fully comparable with German steels and their quality allows prolongation of NPP operating lifetime over projected 40 years. The embrittlement of CrMoV steels is very low due to the dynamic recovery of radiation-induced defects at reactor operating temperatures. Positron annihilation spectroscopy techniques can be effectively applied for evaluation of microstructural changes caused by extreme external loads by proton implantation, with aim to simulate irradiation and for the evaluation of the effectiveness of post-irradiation thermal treatments. We used our actual and previous results, collected during last 20 years from measurements of different reactor pressure vessel steels in "as received", irradiated and post-irradiation annealed state and compare them with the aim to contribute to general knowledge based on experimental positron annihilation spectroscopy data