In-pile heat conduction model of the dispersion nuclear fuel plate with particle agglomeration. Part I: Numerical method and analysis of influencing factors

Abstract

Within a dispersion nuclear fuel plate element, a substantial amount of fuel particles distribute non-uniformly and exhibit the local agglomeration phenomenon, resulting in a reduction in the thermal transfer efficiency. The main aim of this study is to develop the numerical calculation method for the effective thermal conductivity of the dispersion nuclear fuel plate along the thickness direction under an unique in-pile thermal transfer pattern, and determine the influencing mechanisms of key parameters, in particular the particle agglomeration. A modified analytical model, incorporating the influence of particle agglomeration, was constructed based on the equivalent transformation approach for calculating the effective thermal conductivity. Furthermore, according to the in-pile heat conduction mode of the dispersion fuel meat, an internal heat source model was developed and numerically implemented in FEM simulations. Extensive analyses were conducted to investigate the influencing mechanisms of crucial microstructural parameters. Simulation results suggest that the extent of particle agglomeration shows an apparent power law relation with the effective thermal conductivity. The in-pile thermal transfer pattern substantially impairs the inherent thermal conductivity across the meticulously refined dispersion meat structure. This study lays a foundation for optimizing the design of dispersion nuclear fuel plate and enhancing the safety of reactor cores.