Study on Preparation and First-Stage Sintering Kinetics of ThO₂-UO₂ Pellets Made by Sol-Gel Microspheres Technique

The sol-gel method, which is among the methods used for the production of ThO₂-UO₂ mixed oxide fuel pellets, allows a high degree of micro-homogeneity of uranium and thorium in the solution stage. The present study seeks to develop an alternative method in order to produce mixed thorium-uranium dioxide fuel pellets, prepared by internal gelation technique of sol-gel process. The study also aims to investigate shrinkage behavior and first-stage sintering kinetics of pellets compacted in the Ar-5%H₂ atmosphere using a dilatometer. The chemical and physical properties such as density, homogeneity, O/M ratio, metallic impurities, unit cell parameters, phase contents and surface area of powders, that have different compositions of thoria-urania, were studied. The influences of sintering parameters on the characteristics of microspheres and on the properties of sintered pellets are discussed.