Numerical calculation and modeling method of equivalent thermal conductivity of U<sub>3</sub>Si<sub>2</sub>-Al dispersion fuels

<bold>Background</bold>U₃Si₂-Al dispersion fuel is widely used in research and test reactors due to its high uranium density and excellent thermal properties.<bold>Purpose</bold>This study aims to accurately calculate the equivalent thermal conductivity (ETC) of U₃Si₂-Al dispersion fuels based on its microstructural characteristics.<bold>Methods</bold>Firstly, an automated modeling script was developed in conjunction with ABAQUS software to construct finite element models with randomly distributed polyhedral U₃Si₂ particles in an aluminum (Al) matrix and to perform heat transfer calculations. Then, effects of different simplified modeling methods on the calculated ETC were investigated. Finally, the ETC calculation results of 2D/3D finite element models with various particle volume fraction/factor under different temperatures were comparatively analyzed.<bold>Results</bold>The results show that, for U₃Si₂ particle volume fractions of 20% to 35% and temperatures ranging from 300 K to 673 K, the ETC calculated by the finite element method agrees well with the results from the Maxwell-Eucken model. The ETC obtained from two-dimensional finite element models is approximately 16% lower than that from three-dimensional models. When the particle volume factor exceeds 0.66, simplifying the U₃Si₂ particles as spherical and regularly distributed yields a relative deviation of less than 2.1% in the ETC calculation.<bold>Conclusions</bold>Results of this study demonstrate that simplifying the shape and distribution of fuel particles can ensure the accuracy of the equivalent thermal conductivity calculation for U₃Si₂-Al dispersion fuels while improving the efficiency of modeling and computation.