Determination of activation energy of sintering of ThO2-U3O8 pellets using the master sintering curve approach

ThO2 containing around 2 to 3 % U233O2 is considered as fuel for the forthcoming Indian Advanced Heavy Water Reactor (AHWR). High-density ThO2-UO2 pellets have been fabricated by powder metallurgy route using ThO2 and U3O8 powders as the starting materials. U3O8 decomposes to UO2 during high temperature sintering and forms a solid solution with ThO2. The densification behaviour and sintering kinetics of the above were evaluated using a high temperature dilatometer using constant heating rate experiments. To evaluate the activation energy of sintering, a master sintering curve approach has been used. The activation energy for sintering for the above composition in air was found to be 500 kJ/mol.