Mirzov I. Stress-strain state of the WWER-1000 reactor internals

The work is devoted to modeling of the irradiation swelling of the core baffle and core barrel of the WWER-1000 reactor, as well as the analysis of stress-strain state of these structures after prolonged terms of operation. The existing mathematical models of irradiation swelling have been reviewed and an improved model have been offered in which swelling and creep deformations are presented in tensor form and depend on the residual welding stresses. Calculation studies using the developed model have shown that deformation of the core baffle due to irradiation swelling may result in contact with the core barrel. The effect of temperature deformation, irradiation swelling and creep and the level of residual stresses generated during welding and PWHT on the stress-strain state of the internals have been investigated. It is shown that the greatest contribution to the stress state of core barrel can make contact with core baffle. It is shown that the contribution of residual welding stresses in the general stress state of core baffle decreases during operation. A quantitative relationship between the level of residual stresses on the time is obtained.