Use of modified bitumens for fixation of radioactive concentrates

Bitumens applied to the solidification of radioactive concentrates form nuclear power plant operation are modified with a view to increasing the operating reliability of the bituminization technology and improving the resulting properties of the bituminous material, particularly reducing the leachability of radionuclides and compounds, increasing their radiation stability, and increasing the radioactive concentrate content of the bitumen matrix. The following modifiers were used in the treatment: K300 and K1000 polypropylene oil, atactic polypropylene, and low-molecular-weight polyethylene. The bituminous matrices included soft bitumen types: A-80, AP-80 and AP-25. The basic physico-chemical properties of the matrices and modifiers are reported. The modified bitumens for processing modeling and radioactive concentrates from the Bohunice V-1 nuclear power plant were also tested on a pilot plant scale. The results give evidence that the degree of fixation in the modified bitumens can be increased from 40% to 50-55%. The leachability of salts and radionuclides from the bituminous samples is of the order of 10-5 g/cm2.day. (Z.S.). 10 tabs., 12 refs