Development of subchannel thermal-hydraulic analysis code for dual cooled annular fuel

Abstract

Regarding the geometric structural characteristics of innovative dual cooled annular fuel and the possibility of heat split and flow distribution among the internal and external channels, the development of new computational tools is essential for estimating safety margins and accurate assessment of its thermal-hydraulic performance. The SADAF code (Subchannel Analysis Dual cooled Annular Fuel) by COBRA-EN code is developed for this purpose. In the SADAF code, using COBRA-EN code for subchannel analysis in internal and external subchannels, a program has been developed to compute new variables that need to be considered in the thermal-hydraulic assessment. Also, fuel heat transfer calculations were performed by the finite difference method. Benchmark calculations have been performed for Westinghouse 13 × 13 annular fuel rod design, the results were compared with the reference values, and a good agreement was found. Evaluation of the results shows that the total pressure drop predicted by the SADAF code differs from the benchmark results by less than 1%. This difference is about 0.4%, 1.0 K, and 1.0% for fluid temperatures, rod surface temperatures, and flow rates, respectively. It is also shown that these error levels are within acceptable margins. The results analysis exhibited the robustness of the SADAF code in sub-channel analysis of annular fuel assembly.