Densification behaviour of UO2-50%PuO2 pellets by dilatometry

The sintering behaviour of UO2-50%PuO2 pellets has been studied using a dil atometer in inert, reducing and oxidising atmospheres. The shrinkage begins at a much lower temperature in oxidising atmosphere such as CO2 and commer cial N-2. The shrinkage rate was found to be maximum for pellets sintered i n N-2 atmosphere. The mechanism for the initial stage of sintering was foun d to be volume diffusion for both oxidising and reducing atmospheres. The a ctivation energy for the initial stages of sintering was found to be 365 an d 133 kJ/mol for Ar-8%H-2 and CO2 atmospheres, respectively. The activation energy obtained using the Dorn method matches well with that obtained usin g the rate controlled sintering process. The lower activation energy obtain ed in the oxidising atmosphere is explained with the help of models availab le in the literature. (C) 1999 Elsevier Science B.V. All rights reserved.