Study of fine-particle media, because of their high sorption capacities, is of particular importance for the use as backfill
materials in waste repository design, and because argillaceous formations are particularly suitable as host rock formations.
In this study, sorption and retardation characteristics of strontium in fine-particle media were studied to evaluate the distribution
coefficient (Kd) and retardation factor (Rd) of this radioactive element in fine-particle media, which was comprised of selected particles with a diameter less than
1 mm from a candidate site to dispose very low level waste (VLLW). The results indicated that Kd values of strontium under different initial concentrations ranged between 20 and 110. Values of strontium Rd measured from column experiments ranged between 36 and 102, with the corresponding Kd values, determined from solving the inverse problem of Rd calculating formula, ranging between 5 and 20. In conclusion, the Kd value of Sr from the batch tests was found to be higher than these from the column experiments.