Integration of CFD Into Systems Analysis Codes for Modeling Thermal Stratification During SFR Transients

Abstract

The whole-plant systems analysis code SAS4A/SASSYS-1 has been coupled with a computational fluid dynamics code to assess the impact of high-fidelity simulations on safety- related performance for a sodium-cooled fast reactor (SFR). With the coupled capability, it is possible to identify critical safety-related phenomenon that cannot be resolved accurately with existing tools. In this work, the impact of coupling is demonstrated by evaluating plenum thermal stratification during a protected loss of flow transient. Stratification is shown to significantly alter core temperatures and flows predicted during natural circulation conditions. Significant temperature and flow impacts were also observed in the secondary coolant system, suggesting that resolving thermal stratification has far-reaching impacts on the whole plant.