X-ray diffraction study of cation interdiffusion in mixed UO₂-PuO₂ compacts

Abstract

Cation interdiffusion kinetics in mixed oxide (UO₂+PuO₂) compacts is studied using x-ray powder diffraction technique. A profile deconvolution method based on Fourier analysis is developed and used to characterise the degree of homogenisation in the sintered compacts. A concentric core-shell diffusion model in which UO₂ constitutes a solute core enveloped by PuO₂, acting as solvent, is adopted. The radial diffusion equation is solved for appropriate boundary conditions to yield a relationship between the annealing time and the degree of homogenisation. This relationship is used to estimate the interdiffusion coefficients at various temperatures.