Restoration of mechanical properties of irradiated steel by thermal annealing

During operation a reactor vessel is exposed to neutron irradiation fluxes, which causes degradation of the mechanical properties of the vessel material. This concerns primarily, the change in the critical temperature of brittleness and other characteristics of the fracture viscosity of steel. Heating steel above the irradiation temperature, thereby increasing the diffusion mobility,of point defects, is a prerequisite for the appearance of thermodynamic instability, of various radiation damage of steel and, consequently, creates the conditions for restoration of the mechanical properties. In this paper the factors influencing the effectiveness of the restoration of. the critical temperature of brittleness of materials of water-moderated water-cooled power reactor vessels with post-radiation annealing are examined.