Sintering studies on UO2-PuO2 pellets with varying PuO2 content using dilatometry

The sintering behaviour of UO2, PuO2, UO2-20%PuO2, UO2-50%PuO2 and UO2-76%P uO2 pellets have been studied using a dilatometer in inert, reducing and ox idizing atmospheres. The onset of shrinkage occurs by about 400 degreesC lo wer in oxidizing atmosphere such as CO2 and commercial N-2 than that occurs in reducing atmosphere. PuO2 and UO2-76%PuO2 showed an expansion on heatin g in Ar at similar to 1000 degreesC. UO2-20%PuO2 pellet sinters slightly be tter in Ar than in Ar-8%H-2. From the shrinkage rate curves, it was found t hat the maximum shrinkage rate occurs in commercial nitrogen atmosphere for UO2-50%PuO2. For the other compositions, the maximum shrinkage rate was ob served for Ar atmosphere. The sintering behaviour of above mentioned pellet s was discussed with the help of point defect model and the possible mechan isms were suggested. (C) 2000 Elsevier Science B.V. All rights reserved.