Enhanced Chemical Cleaning of Waste Tanks to Improve Actinide Solubility
CX(s) Applied: B3.6
Location(s): Aiken, South Carolina
Office(s): Environmental Management, Savannah River Operations Office
Presently, residual sludge in Savannah River Site (SRS) waste tanks will be removed by dissolution in oxalic acid using solutions containing up to 0.9 M oxalate. Little actinide removal has been observed during tests of the oxalic acid treatment, probably due to the low solubility of the actinide materials formed when the acid solutions were neutralized in the separations facilities. The plutonium (Pu) in the sludge is reported to be present as hydrated and crystalline oxides. Extensive studies have evaluated the solubility of hydrated Pu oxides in alkaline solutions including some studies of Hanford and SRS wastes. Based on these and other studies, a series of alkaline and mildly acidic solutions were selected as candidates which could potentially increase the solubility of the actinides in residual sludge. The candidate solutions will be evaluated in solubility experiments using an actinide sludge. The experimental program involves preparing the surrogate solids, treating samples of the solids with the selected solutions, and measuring the effectiveness of dissolution. The intent of the study is to identify promising candidates for subsequent investigations.