Effects of Nb₂O₅ and UO₂ Powder Types on Sintered Density and Grain Size of the UO₂ Pellet

The variation of sintered density and fain size in ex-AUC, ex-ADU and granulated ex-ADU UO pellets in which 0.1~1.0wt% NbO were doped were examined. Pellets were sintered in an atmosphere of H at 1 for 4h. All the specimens tested shooed more than 94% T.D.(Theoretical Density). Sintered density decreased with increasing the amount of NbO. Powder types had little influence on the sintered density. Pore size distribution was shifted to the larger ones as NbO was added. The increase of total pore volume and grain growth due to the addition of NbO were thought to be the cause of the sintered density decrease. The largest grain size was seen in the 1. 0wt% NbO doped ex-AUC UO pellets. Their average size was 13.9 .m}$.