Abstract
Fluid-Structure Interactions (FSIs) occurring inevitably in operating reactor component systems can cause excessive force or stress to the structures resulting in mechanical damages that may eventually threaten the structural integrity of components. In particular, thermal stratification in the pressurizer surge line has been addressed as one of the significant FSI phenomena in reactor systems. In this study, a thermal-stress simulation is performed using ANSYS FSI. The 3-dimensional transient temperature distributions in the wall of an actual PWR pressurizer surge line subjected to thermal stratification is calculated by CFD analysis either during out-surge or in-surge operation. The thermal loads from CFD analysis using ANSYS CFX are transferred to structural analysis code, ANSYS Multiphysics. From this information, thermal stresses are determined and ultimately a fatigue analysis is performed, all within the ANSYS environment. In addition, the thermal stress and fatigue analysis results obtained by applying the realistic temperature distributions from CFD analysis are compared with those by assuming the simplified temperature distributions to identify some requirements for a realistic and conservative thermal stress analysis from a safety point of view.
