Densification behaviour and sintering kinetics of ThO2–4%UO2 pellet

ThO2–⩽4% 233UO2 fuel will be the driver fuel for the forthcoming Advanced Heavy Water Reactor (AHWR) in India. Densification behaviour such as shrinkage and shrinkage rates of the green pellets of ThO2–4wt.% UO2 (natural ‘U’) fabricated by Coated Agglomerate Pelletization (CAP) process were studied using a vertical dilatometer at different heating rates. Activation energy of sintering, ‘Q’, was estimated in the initial stages of sintering by continuous rate of heating (CRH) technique as proposed by ‘Wang and Rishi Raj’ and ‘Young and Cutler’. The sintering mechanism was identified to be as the grain boundary diffusion (GBD) and the average ‘Q’ value obtained by these two methods were found to be 350 ± 16 kJ/mole and 358 ± 5 kJ/mole, respectively.