Preparations for High-Level Defense Waste Immobilization at Savannah River Plant

摘要

Methods are being developed to immobilize Savannah River Plant (SRP) wastes in high-integrity glass forms. The waste forms will be suitable for storage in an on-site facility or for shipment to an off-site repository. Alkaline wastes produced in SRP separations plants are currently stored in large, carbon-steel tanks. These wastes consist of a water-soluble fraction (salt cake and supernatant liquor) and an insoluble sludge. The water-soluble fraction contains most of the exp 137 Cs and the insoluble sludge contains most of the exp 90 Sr, waste actinides, and other fission products. exp 90 Sr and exp 137 Cs are the most hazardous radionuclides in aged waste. A conceptual solidification process has been developed from laboratory tests with both actual and simulated waste. Engineering design studies are in progress. First, wastes are removed as a slurry from the waste tanks. The sludge is separated from the supernate, and then exp 137 Cs is removed from the clarified supernate by ion exchange. The resulting decontaminated supernate is evaporated to a salt for bulk storage. In the second part of the process, exp 137 Cs is mixed with sludge and the mixture is calcined and then solidified in borosilicate glass. Off-gas from the calciner and glass melter is treated to ensure that no hazardous materials are released to the atmosphere. (ERA citation 03:052143)