Modeling of the Thermal Conductivity of U-Mo/Al Dispersion Fuel

Abstract

Thermal conductivity of U-Mo/Al dispersion fuel was empirically modeled. The modeling expanded one of the most widely accepted theoretical models for a composite material, the Bruggeman model.

The Bruggeman model, as other theoretical models commonly do, assumes perfect contact between the fuel particles and Al matrix and also assumes the Al matrix is a defect-free monolithic continuum. However, it is known that the U-Mo particle surface has a thin oxide layer, so the contact between the U-Mo and Al is partial. The Al matrix is also made of Al powder, which makes the Al matrix a thermally imperfect medium. Because of these factors, the theoretical model predicts substantially higher than the measured. In addition, the theoretical model lacks a capability to consider the effect of fuel particle size.

The newly developed model considers thermal resistances at the interfaces between the U-Mo and Al and the Al-Al interfaces, which were expressed as a function of U-Mo particle size and Al particle size, respectively, and empirically obtained by data fitting of measured data available in the literature.