Decontamination of alkaline radioactive waste by ion exchange

An ion-exchange process was developed to remove cesium-137, strontium-90, and plutonium from alkaline salt solutions. About 20 million gal of alkaline salt cake and supernatant solution from processing nuclear fuels and materials for defense programs are presently stored at the Savannah River Plant. Ion exchange may be used to decontaminate this radioactive waste during a proposed waste solidification program. In development tests 100-L quantities of liquid waste were decontaminated. Decontamination factors were 4 x 105 for 137Cs, 5 x 103 for 90Sr, and 300 for Pu. The separated radionuclides were concentrated by a factor of 1500 and immobilized by adsorption onto zeolite. Residual 137Cs, 90Sr, and Pu activity in the decontaminated product was about 6 nCi/g. 106Ru, the most hazardous radionuclide remaining after 137Cs removal, will decay to 6 nCi/g about 10 years after the waste is processed