Radiation-Induced Phase Formation in Steels of VVER Reactor Pressure Vessels Containing ~0.3–1.3 wt % Nickel

Abstract

The radiation-induced structural elements in the materials of water-moderated water-cooled reactor pressure vessels have been studied by TEM and atomic probe tomography at the National Research Center Kurchatov Institute. The effect of Ni concentration in the range from 0.34 to 1.28 wt % on the formation of phases under fast neutron irradiation has been analyzed. The volume density of radiation-induced phases has been shown to depend on the Ni concentration in steel; the phase sizes and compositions remain almost the same. The volume density of these precipitations affects the radiation hardening, one of the radiation embrittlement mechanisms. The quantitative parameters of radiation-induced phases have been shown to control the service life growth, the enhancement of the thermal stability, and the melting technology of reactor vessel steels bearing nickel in the 0.3–0.7 wt % range.