Development of an Ion-Exchange Process for Removing Cesium from High-Level Radioactive Liquid Wastes
A process is now being developed to solidify and isolate the biologically hazardous radionuclides from approximately 20 million gallons of alkaline high level radioactive waste accumulated at the Savannah River Plant (SRP) and now being stored in large underground tanks. The waste consists mainly of liquid waste supernate, a damp sodium salt cake and a gelatinous, insoluble sludge. The process involves dissolving the salt cake in water, separating it from the sludge, washing the sludge and adding the washings to the dissolved salt cake. The aqueous portion is then treated by ion exchange to remove cesium-137, plutonium and other actinides and soluble strontium-90. After elution, the cesium and actinides are concentrated by evaporation and immobilized on zeolite. The strontium is similarly concentrated. The cesium-zeolite and strontium concentrate are combined with washed sludge for calcination. The calcined mixture is melted with glass frit to form a leach resistant glass. The final glass is encased in 0.8 m3 metal canisters. The decontaminated aqueous waste is concentrated by evaporation and returned to cleaned underground tanks for storage as a salt cake.
KeywordsBreakthrough Curve Column Volume Radioactive Liquid Waste Decontamination Factor Cesium Concentration
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