Diffusion of ⁹⁹Tc in granite under aerobic and anoxic conditions

The diffusion of ⁹⁹Tc in granite was studied under aerobic and anoxic conditions. The distribution coefficient for weakly adsorbed radionuclide (K_a<1 ml/g) was obtained from diffusion experiments. The results show that the diffusion curves yielded by C_t/C_o against time are accordant with the theoretical breakthrough curves. The apparent diffusion coefficient of 99Tc in granite samples under anoxic conditions is less than that under aerobic conditions. The existence of CO₃²⁻ accelerates the migration of ⁹⁹Tc. The apparent diffusion coefficient of ⁹⁹Tc in granites decreases with the increase of reductive components of granite, whereas the distribution coefficient of ⁹⁹Tc in granites increases with the increase of reductive components of granite.