Numerical calculation and modeling method study on effective thermal conductivity of U3Si2-Al dispersion fuels

[Background]: U3Si2-Al dispersion fuel is widely used in research and test reactors due to its high uranium density and excellent thermal properties. [Purpose]: This study aims to accurately calculate the effective thermal conductivity of U3Si2-Al dispersion fuels based on its microstructural characteristics. [Methods]: An automated modeling script was developed in conjunction with ABAQUS software to generate finite element models featuring randomly distributed polyhedral U3Si2 particles in an aluminum (Al) matrix and to perform heat transfer calculations. The effects of different simplified modeling methods on the calculated effective thermal conductivity were also investigated. [Results]: The results show that, for U3Si2 particle volume fractions of 20% to 35% and temperatures ranging from 300 K to 673 K, the effective thermal conductivity calculated using the finite element method agrees well with the results from the Maxwell-Eucken model. The effective thermal conductivity 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 effective thermal conductivity calculation. [Conclusions]: Therefore, simplifying the shape and distribution of fuel particles can ensure the accuracy of the effective thermal conductivity calculation for U3Si2-Al dispersion fuels while improving the efficiency of modeling and computation.