CFD-Based Parametric Optimization of Heat Transfer Correlations in Corium-Cooled Core Catchers of Sodium-Cooled Fast Reactors (SFRs)

Abstract

Sodium-cooled fast reactors (SFRs) represent a key advancement for next-generation nuclear power systems due to their excellent thermal efficiency and inherent safety. However, managing the heat released, especially from the core melt, a molten mixture of nuclear fuel and structural materials, remains a key design and safety challenge in severe core meltdown scenarios. This study presents a parametric optimization of heat transfer in a sodium-cooled fast reactor heat capture system based on computational fluid dynamics (CFD). A detailed CFD model was developed using SimFlow OpenFOAM to simulate the thermal-hydraulic behavior of a typical heat trap system. The model takes into account realistic thermal properties of the core melt and liquid sodium, steady-state flow assumptions, and variable parameters including core melt temperature (500–800 K), sodium coolant flow rate (10–50 m/s), fuel rod spacing, and containment thickness. The numerical simulations aim to quantify the effects of geometry and flow conditions on local and global heat transfer characteristics. The results show that the optimized design configuration can improve the heat removal efficiency by up to 25% and reduce the coolant pressure drop by about 15%. In addition, the model predicted the heat transfer coefficient with an average absolute error of 10.2% compared to experimental data. This study demonstrated the effectiveness of computational fluid dynamics (CFD) as a design prediction and optimization tool for thermal management of sodium-cooled fast reactors and highlights the importance of integrated parametric studies for developing safer and more efficient reactor designs. These results provided valuable input to core heat transfer modeling and provide guidance for design strategies for future advanced nuclear reactor systems.

Keywords: Sodium-Cooled Fast Reactors, Computational Fluid Dynamics, Corium Heat Transfer, Flow Rate.