The feasibility of incorporating radioactive wastes in asphalt or polyethylene

Residues from aqueous and organic intermediate- level radioactive waste can be incorporated in asphalt or polyethylene to reduce the mobility of radionuclides after burial or storage of the solidified waste product. Asphalt or polyethylene products containing up to 60 wt% of nonoxidizing inorganic solids have a chemical resistance similar to that of pure asphalt or polyethylene. Leach rates projected over 200 years indicate that ~5% of a soluble element (sodium or cesium) or 0.6% of an insoluble nuclide (106Ru) would be leached from a 55-gal drum of product submerged in water. Polyethylene accommodated up to 40 wt% of organic liquids, such as tributyl phosphate (TBP), while asphalt products containing 25% TBP were not entirely satisfactory. Polyethylene products were also superior to asphalt products in flammability and radiation stability tests. Incorporation in asphalt is not recommended for waste solids containing significant amounts of oxidants.