The results of the two-detector coincidence measurements of the Doppler broadening of annihilation radiation on a variety of the reactor pressure vessel steels of VVER type are reported. The following subjects were studied: (i) The non-irradiated materials. (ii) The changes induced by neutron irradiation as a function of fluence and flux. (iii) The effect of the regeneration annealing of irradiated materials. The irradiation-induced migration of Cu atoms towards positron annihilation sites in dislocations was observed which turned out to be removed by annealing at 475 degreesC.