Removal of Radionuclides from Hanford Defense Waste Solutions

摘要

The Hanford high-level defense wastes were characterized by their large volume (190,000 m exp 3 ) and varying content of inert and radioactive constituents. The water-soluble portion (140,000 m exp 3 ) of these wastes, which consists mainly of NaNO sub 3 , NaAl(OH) sub 4 , Na sub 2 CO sub 3 and other sodium salts, contains a few milligrams of long-lived (t/sub 1/2/ greater than or equal to 10 years) radionuclides per 1000 kilograms. There is probable economic incentive for long-term management of Hanford defense wastes to partition them into a small volume of highly radioactive material requiring high integrity immobilization and storage and a much larger fraction of low level (e.g., < 10 nCi/g) waste which can be economically and safely stored in bulk form. To aid in achieving this latter objective, an integrated series of aqueous separations processes (precipitation, ion exchange, and solvent extraction methods) was designed to remove exp 137 Cs, exp 90 Sr, actinides, other multivalent cationic fission and activation products, and exp 99 Tc from the water-soluble wastes. Results of generally satisfactory laboratory-scale tests of radionuclide removal technology with actual Hanford wastes are described. (ERA citation 05:020149)