TEMPERATURE MARGIN ESTIMATION OF BRITTLE FRACTURE FOR REACTOR PRESSURE VESSEL DURING EMERGENCY MODE

Abstract

There are 15 RPV units in Ukraine at the four nuclear power plants. Most of them have completed their design working life (30 years). Calculation of the brittle strength is one of the main estimation to exist life of the reactor pressure vessel under their design resource. Currently in Ukraine there are 4 different regulatory techniques. That allow for specifying calculations for reactor life extension in over the project period. In addition, the supervisory authority requires coordination of positions with the relevant IAEA documents. However, these documents do not only contradict each other, but none of them hasn't details of tests to justify the correct application of accepted numerical schemes, geometrical patterns and submodel, density grid, select the type of finite element. A significant problem is the absence of specific guidance on the use of modern software codes for computing SIF in time in the presence of elastic-plastic deformation including the presence of residual stresses. All of this hasn't objectivity for assessment accuracy of calculation, loss of material, formulating unreasonable demands expertise and delaying the appearance of different approaches and universal ways.In this article are shown the technique of calculating reactor vessel VVER-1000 in fragile strength.By using modern software codes are simulated real emergency operating mode and temperature margin of brittle fracture.