Research on the Applicability of the IWF Model to Coupled Heat Transfer Between Intra- and Inter-Assembly in LFR

Abstract As one of the Gen-IV advanced nuclear reactors, the lead-based fast reactor (LFR) has high power density, strong inherent safety, and excellent maneuverability, which makes it easy to realize modularization and miniaturization and can be used for conventional power production and energy supply needs of remote areas. The premise of the engineering application of LFR is to ensure the safety and reliability of reactor operation, the research of thermal-hydraulic and safety characteristics is quite important for the design and optimization of LFR. In this study, a numerical analysis method was used to analyze the coupled heat transfer characteristics between intra- and inter-assembly in LFR. Two different models, the multi-layer wall model and the IWF sub-channel model, were studied to characterize the effects of the inter-wrapper flow (IWF). These two models were validated and compared based on the IWF experiment carried out by German KIT with the THESYS experimental platform. The results show that the accuracy of the IWF sub-channel model is higher under different working conditions, and the deviation between the fluid temperature in the inter-assembly and the experimental value is less than 2%. The calculation accuracy of the multi-layer wall model is acceptable for the low IWF flow rate, and the deviation increases gradually with the IWF flow rate. Based on the IWF sub-channel model, the axial fluid temperature distribution in IWF was further analyzed under different non-uniform boundary conditions.