Sorption and Transport Behavior of ¹³⁷Cs, ⁹⁰Sr, and ⁹⁹Tc on Geological Media in Radioactive Waste Repository, South Korea - 16112

Sorption experiments and a behavior investigation for the radionuclides ¹³⁷Cs, ⁹⁰Sr, and ⁹⁹Tc were conducted using groundwater and solid materials (mud-stone and sandstone) sampled from the Wolsong low- and intermediate-level radioactive waste repository at Gyeongju, Korea. After experiments involving batch sorption, diffusion, and a flow-through column, distribution coefficients (K_d) of the radionuclides were obtained, and sorption properties for each radionuclide were analyzed. Increasing K_d values were observed in the sequence ¹³⁷Cs, ⁹⁰Sr, and ⁹⁹Tc regardless of the geological media tested. For all sorbing radionuclides, K_d values for the mud-stone were observed to be higher than those for sandstone regardless of the groundwater. These higher K_d values are the result of higher levels of total organic carbon in the mud-stone than were present in the sandstone. In addition, the chlorite, kaolinite, and montmorillonite contents in the mud-stone also were higher than in the sandstone. The mineralogical composition of the solid materials was observed to be important in the sorption of sorbing radionuclides. (authors)