Thermal-hydraulic sensitivity analysis of annular fuel based on grey fuzzy theory

BackgroundAnnular fuel has the potential to significantly enhance the power density of Pressurized Water Reactor (PWR) cores. This characteristic holds great significance for the realization of the miniaturization design of reactors and the improvement of their economic efficiency. Previous study in this domain has primarily focused on the arrangement patterns of components and a limited number of geometric dimension combinations. Conversely, there has been relatively less research dedicated to the quantitative analysis of the refined geometric structure dimensions of fuel elements.PurposeThis study aims to quantify the impact of various geometric factors on the thermohydraulic performance of annular fuel.MethodsFirst of all, the single-channel model of annular fuel was adopted as the research subject. Thermohydraulic design calculations were carried out based on the parameters of the PWR annular fuel elements designed by Westinghouse. Then, geometric factors, including the inner and outer diameters of the inner and outer claddings and the inner and outer diameters of the fuel pellets, were selected to establish four evaluation criteria. Finally, the grey relational analysis and the theory of fuzzy mathematics were employed to quantify the influence of each geometric factor on the thermohydraulic performance.ResultsThe calculation results indicate that the sensitivity of various geometric factors is comparable in terms of the minimum departure from nucleate boiling ratio (MDNBR) in both inner and outer channels. However, significant differences are observed in the adiabatic plane location and the maximum fuel pellet temperature.ConclusionsAmong these geometric factors, the dimensions of the fuel pellet itself exhibit the highest sensitivity to the adiabatic plane location, while the outer and inner diameters of the cladding show the highest sensitivity to the maximum fuel pellet temperature. This quantitative approach provides a valuable reference for the design and parameter adjustment of annular fuel in PWRs.