Sorption experiments for radionuclides such as 14C, 99Tc, 137Cs, 90Sr, 63Ni, and 241Am were conducted using two different groundwaters (GM-1 and SS-5) and solid materials (granodiorite and fracture-filling
material) sampled from the Wolsong low- and intermediate-level radioactive waste (LILW) repository, Gyeongju, Korea. The distribution
coefficients of the radionuclides, Kd’s, were obtained and their sorption properties were discussed for each radionuclide. For all sorbing radionuclides, the Kd values for the fracture-filling material were observed to be higher than those for granodiorite regardless of the groundwater.
The Kd values were increased in the sequence 99Tc < 14C < 90Sr < 137Cs < 63Ni < 241Am regardless of sorbent types implying that the sorption of radionuclides onto geological media is affected by their chemical
behavior in accordance with geochemical environments. Anionic radionuclides such as 14C and 99Tc showed very low Kd values both for the granodiorite and fracture-filling material. The mineralogical composition of the geological media and
groundwater conditions was also observed to be important in the sorption of sorbing radionuclides, especially in the case
of strongly sorbing radionuclides.