Features of Macro- and Microstructure of the Weld Metal of VVER Reactor Pressure Made Using Ceramic Flux in the Initial and Irradiated States

In this paper, a comparative analysis of the macro- and microstructure features of the weld metal for VVER-type reactor pressure vessel made using ceramic flux is performed in the initial and irradiated states compared to the weld metal made using standard technology. It is shown that the weld made using ceramic flux is characterized by a reduced yield strength of metal and a lower level of grain boundary segregations. Calculation and experimental assessment of radiation hardening showed an increase in the yield strength by 108 MPa. This value of radiation hardening turned out to be equal to the characteristic value for the metals of welds for VVER-type reactor pressure vessel with a close nickel content irradiated to a fast neutron fluence corresponding to the design value for a service life of 60 years. As a result, a conclusion was made about a decrease in the susceptibility of the investigated weld material to radiation embrittlement.