Investigation of first-stage sintering kinetics of UO2, ThO2 and (Th,U)O2 pellets manufactured by internal gelation technique of sol-gel process

The sol-gel process which is among the methods used for the production of UO2, ThO2 and ThO2-UO2 mixed oxide fuel pellets allows a high degree of micro-homogeneity of uranium and thorium in the solution stage. The first aim of this study was to develop an alternative method to produce uranium, thorium and mixed thorium-uranium dioxide fuel pellets by using internal gelation technique of sol–gel process. The second aim was to investigate shrinkage behavior and first-stage sintering kinetics of pellets compacted in the Ar-%5 H2 atmosphere using dilatometer. Shrinkage curves of the UO2, ThO2, ThO2-10%UO2 and ThO2-5%UO2 pellets obtained from the dilatometer were used to determine the sintering mechanism, the diffusion coefficients and the activation energy.