Whole core thermal-hydraulic analysis considering inter-wrapper flow phenomena in the liquid metal cooled fast reactor

摘要

The inter-wrapper flow (IWF) phenomenon is identified as an integral part of the full core thermal-hydraulic simulation for liquid metal cooled fast reactors. In this work, a whole core thermal-hydraulic simulation code based on the subchannel analysis method, named KMC-FBc, is developed. Both the "two-step" and pin-by-pin level methodologies are investigated together with several inter-wrapper flow and heat transfer models, which are numerically solved simultaneously. To validate the code, it is compared with the experimental data from KALLA-IWF test and the numerical simulation results from computational fluid dynamics (CFD). Both normal conditions and flow blockage scenarios show that the pin-by-pin level method has better accuracy than the two-step method. An in-depth assessment of the influence of different IWF models on the medium-power lead-cooled fast reactor M~2LFR-1000 is performed. Current results indicate that IWF heat transfer has little effect on the maximum temperatures and overall thermal-hydraulic characteristics under nominal conditions, while in the internal flow blockage scenario, IWF heat transfer will greatly reduce the maximum temperatures of fuel pellets and cladding, which can improve the accuracy of the whole core thermal-hydraulic analysis and provide margins for future reactor design and optimization.