LEACHING OF RADIONUCLIDES IN CHERNOBYL FALLOUT FROM SOIL BY MINERAL ACIDS

The leaching of Sr-90, Zr-95, Ru-106, Cs-134, Cs-137, and Ce-144 by HC l and HNO3 solutions from variously contaminated homogeneous soils col lected in 1986 in several regions of Russia, Belarus, and Ukraine is s tudied. The dissolution of radionuclides in 1 and 6 M HCl from soils c ontaminated by fallout of fuel particles was several times less than f rom soils contaminated by condensed aerosol particles. The isotopes Zr -95 and Ce-144 were least soluble. Their extraction depended on [HCl] and the conditions although it did increase at collection sites furthe r from the radioactive-release site, reaching 30-50%. The extraction o f Ru-106 from soil varied from 4-7 to 80%. This is consistent with dif ferent physicochemical Ru species in fallout. The higher solubility of Sr-90 and the greater Sr-90/Ce-144 ratio in soils from regions with c ondensed fallout indicate that it was scattered not only in dispersed fuel particles but also in another physicochemical form.