Densification behaviour of ThO2-PuO2 pellets with varying PuO2 content using dilatometry

The shrinkage behaviour of ThO2, ThO2-30%PuO2, ThO2-50%PUO2 and ThO2-75%PuO2 pellets has been studied using a dilatometer in inert (Ar) and reducing atmospheres (Ar-8%H-2). The effects of dopants of CaO and Nb2O5 on shrinkage of the oxides of the above Pu/(Pu + Th) ratios were also studied. Out of the two dopants studied, CaO was found to give larger shrinkage for all the Pu/(Pu + Th) ratios covered in this study. It was also found that the shrinkage was marginally larger in Ar-8%H-2 than in Ar atmosphere. Addition Of PuO2 to ThO2 enhanced sintering. This was found to be true for both the dopants. During the sintering of ThO2, a prominent peak was observed in the shrinkage curve at around 100-300degreesC. This peak was attributed to the pressure increase of the trapped gases which subsequently release at high temperatures. (C) 2003 Elsevier Science B.V. All rights reserved.