Determination of sorption and diffusion parameters of ⁹⁹Tc in crushed granite using through-diffusion experiments

Diffusion and sorption are important processes associated with radionuclides migration in crystalline rock. These processes are studied in the laboratory using borehole core samples. In this study, we obtained distribution coefficients (K_d), apparent diffusion coefficients (D_a) and retardation factor (R_f) using batch and through-diffusion experiments. The R_f ^H/Tc and K_d ^H/Tc values obtained using the accumulative concentration method were lower than those derived in the batch experiments. These findings demonstrate that reliable R_f and K_d values of ⁹⁹Tc can be obtained using through-diffusion experiments with a non-reactive radiotracer, thereby bolstering confidence in the assessment of the long-term performance of disposal repositories.