Fixation of Actinides in Zirkonium Based Ceramics

In recent years, various fuel types or targets, free from U-238, have been proposed for the transmutation of plutonium and the minor actinides. Yttrium-stabilised zirconia is currently under investigation because of its small neutron cross section and is high solubility with PuO₂ and AmO₂. The aim of the present work is to investigate the behaviour of Yttrium Stabilised Zirconium Oxide in presence of Cerium, as simulate of minor actinides. Several oxide materials composed of Zr, Y, Ce (5–25%), have been synthesised by coprecipitation method at different calcination temperature and the products have been characterised by Optical Microscopy (OM), Thermogravimetry (TG) coupled with Thermal Differential Analysis (DTA), X-ray Line Diffraction (XRD), Scanning Electron Microscopy (SEM) Energy Dispersive X-Ray analyser (EDX) etc. The investigations show that, the structure of the powder, characterised by the phase condition, the lattice parameter, the crystalline size and the lattice distorsion, varies with the CeO₂ content, and has an influence on the sinterability. “Mild” methods of powder preparation (drying, low-temperature calcination, wet grinding by attrition) were used before sintering. For all investigated Cerium concentrations, the optimal parameter of pressing and sintering were determined. For a wide Cerium concentration region, from 5 to 20 wt%, the density of compact materials is 92–95% of TD, the microhardness 13.5 GPa and the pellets have a good morphology, grains and pores being homogeneous distributed in material.