Effect of the Operation Factors on the Properties of the Heat Affected Zone in VVER-1000 RPV according to the Results of Surveillance Specimens

Based on the data accumulated over the 40-year period of operation of VVER-1000 reactor pressure vessels (RPVs), we analyze the results of impact bending tests of control, temperature, and irradiated surveillance specimens cut from the heat-affected zone (HAZ) of the VVER-1000 RPVs. The results of testing HAZ surveillance specimens are compared with the data obtained in testing of base metal specimens obtained by reconstruction method from the HAZ specimens. The causes of a large scatter of the ductile–brittle transition temperatures are discussed.