Nuclear Engineering and Technology (Jan 2025)
Rapid determination of the migration parameters of nuclides in intact granite rock under the action of electric field
Abstract
Deep geologic disposal has been widely accepted as a strategy for long-term disposal of the high-level radioactive waste. It is principal to obtain the migration parameters of radionuclides in natural barrier, such as granite, of a high-level radioactive waste repository for safety assessment of the repository. To quickly determine the diffusion and sorption properties of nuclides in intact granite, two tracers, I− and ReO4−, were tested with a modified electromigration device, by imposing a constant voltage over an intact Beishan granitic rock sample. The breakthrough curves of I− and ReO4− were obtained under condition of five different voltages. To interpret the electromigration experimental results with more confidence, an advection-dispersion model based on first-order adsorption kinetics was developed in this study. Data analysis of the breakthrough curves by this model suggest that the effective diffusion coefficients of I− and ReO4− in intact Beishan granodiorite rock are (6.81 ± 0.53) × 10−13 m2/s and (6.45 ± 0.07) × 10−13 m2/s, respectively. While the distribution coefficient of the two ions are (9.06 ± 1.13) × 10−7 m3/kg and (9.81 ± 0.13) × 10−7 m3/kg, respectively. This indicates that I− and ReO4− hardly adsorb in Beishan granodiorite rock.
