Comparison of PTS analyses of RPVs based on 3D-CFD and RELAP5

• RPV fracture mechanics model based on RELAP5.
• RPV fracture mechanics model based on CFD.
• Comparison of models based on RELAP5 and CFD for fracture mechanics.

The integrity of a reactor pressure vessel related to pressurized thermal shocks is one of the most important issues for the assessment of life time extension of a nuclear power plant. The most critical scenario occurs during cold water injection through the cold leg due to a Loss-Of-Coolant Accident (LOCA). Due to the difficulties associated with the crack modeling with the three-dimensional finite element method (FEM), simple geometries and crack configurations are usually employed.In the present study, a hypothetical medium break LOCA is assumed in one of the hot legs for an adopted reference design of a two-loop pressurized water reactor. The boundary conditions obtained from RELAP5 calculations are used as input for the three-dimensional computational fluid dynamics simulations in order to provide three-dimensional temperature distribution for the structural mechanics analysis in which submodeling and eXtended FEM (XFEM) are applied. The results from these three-dimensional computations are compared with those from simplified axisymmetric models based on reference data temperatures.