Influence of precipitation conditions on the properties of ammonium diuranate and uranium dioxide powders

Abstract

A comprehensive investigation of the factors affecting the properties of ADU precipitates in relation to the properties of the subsequent UO2 powders in pellet fabrication is reported and the importance of precipitation parameters is demonstrated. Variables investigated include continuous single-versus two-stage precipitation, pH, residence time, washing of ADU to remove nitrate, and calcination-reduction conditions. The most important variable was the pH at which precipitation occurred. In particular, this governed the size of agglomerate which determined the settling and filtering characteristics of the ADU slurry. In two-stage precipitation, the ADU properties were determined by the proportion of uranium precipitated at different pH values.