CRYSTALLIZATION CHARACTERISTICS OF AMMONIUM URANYL CARBONATE (AUC) INAMMONIUM CARBONATE SOLUTIONS

Ammonium carbonate solutions with an excessive amount of NH3 were prod uced in a commercial AUC (ammonium uranyl carbonate) conversion plant. In this study the AUC crystals, precipitated with uranyl nitrate and ammonium carbonate solutions prepared in the laboratory, were characte rized to determine the feasibility of recycling ammonium carbonate sol ution. The AUC crystals were easily agglomerated with the increasing c oncentration of CO32- and mole ratio of NH4+/CO32- in ammonium carbona te solution. Effects of a mixing system for the solution in the AUC cr ystallizer and the feed location of the solution on the agglomeration of AUC crystals were also studied along with the effects of agglomerat ed AUC powders on UO2 powders. Finally, the feasibility of manufacturi ng UO2 fuel with a sintered pellet density of 10.52 g/cm3, Using the A UC powders generated in this experiment, was demonstrated.