Study on the thermo-hydraulic behaviors of the new-pattern fuel assembly in lead-based fast reactors based on OpenFOAM

o improve the heat transfer efficiency of the coolant in lead-based fast reactors, this study optimized the configuration and rotational direction of the spacer wires in fuel assemblies to design a new-pattern fuel assembly. This study conducted detailed comparisons between traditional and new pattern fuel assembly rod bundles utilizing the open-source computational fluid dynamics platform, OpenFOAM. The results indicated that the new design may significantly reduce the pressure drop along the rod bundle, which is beneficial for lowering the pressure drop. Furthermore, this new design improved coolant mixing in the subchannels, which facilitated a more uniform temperature distribution and lower thermal gradients at the assembly outlet. These factors collectively reduced the thermal fatigue and creep in nearby internal components. Overall, the new-pattern fuel assembly proposed in this study may have better heat transfer performance, thereby enhancing the Integrated Thermal-Hydraulic Factor by 48.2% compared to the traditional pattern.