Abstract: To study the influence of pressurized thermal shock on the bearing capacity of the nuclear reactor pressure vessel (RPV) with a surface crack, the 3D finite element model was established for the beltline region around the crack by ABAQUS software. The transient temperature field and stress field were obtained. The XFEM was used to simulate the crack propagation in the thermo-mechanical coupling field. The ultimate bearing capacity of the vessel at different nil-ductility transition temperatures was tested employing elastic-plastic fracture analysis, and the results were compared with those obtained from elastic analysis to sum up the fracture characteristics of the material. Through mesh refinement, it was found that the crack propagation paths and the damage degrees for different element sizes are equivalent, which avoids pathological mesh dependence.

Key words: reactor pressure vessel, pressurized thermal shock, XFEM, nil-ductility transition temperature