Evaluation of Uranium Coprecipitation with Sodium Aluminosilicate Phases

Batch laboratory experiments performed to evaluate uranium incorporation into aluminosilicate structures during synthesis are described. This research was conducted in response to plant problems related to the accumulation of uranium with aluminosilicates in low-level radioactive waste evaporators. Conditions that favor precipitation of aluminosilicates also foster uranium solid precipitation, so it is difficult to attribute problems with uranium accumulation to, for example, only the formation of the aluminosilicates. Infrared spectra show that sodium uranates, uranium silicates, and other uranium solids are formed during the synthesis of sodium aluminosilicates structures in the presence of uranium. Both amorphous and sodalite aluminosilicate phases, unlike the zeolite A phase, show appreciable affinity for uranium incorporation during their formation in the presence of uranium.