11:15 AM - 11:30 AM
[HCG20-03] Migration of radioactive nuclides in the saturated buffer medium of the geological SNF (spent nuclear fuel) repository site: based on laboratory experiments
Keywords:radioactive nuclide, engineering barrier, spent nuclear fuel, deep geological repository
The deep geological repository (DGR) is designed with the multi-barrier system to minimize the migration of radioactive nuclide in the spent nuclear fuel (SNF) disposal site. Compacted bentonite medium has been considered as one of the engineering barriers (buffer) to prevent the radioactive nuclide spread from the SNF canister in the repository site. The Korean compacted bentonite (WRK-Bentonil: Waste Repository Korea bentonite) has been considered as the appropriate buffer material for the following Korean SNF repository site. As the SNF is disposed in the storage hole of the bed rock at the repository site, the buffer medium surrounding the Cu-canister containing bundles of SNFs becomes saturated with groundwater and various radioactive nuclides start to dissolve and to migrate from the Cu-canister.
In this study, the laboratory scale core (4.5 cm in diameter and 1.0 cm in length) experiments were performed to quantitatively investigate the migration properties of radioactive nuclides in the saturated compacted WRK-Bentonil. The syringe pump and high pressurized stainless-steel cell with dual outer wall were used to simulate the DGR environment (confining pressure: 5 MPa; injection pressure: 0.3-1.6 MPa; water saturation: 100%). The Cesium (Cs+) and Iodine (I-) were used as representative radioactive nuclides in this study and the powder type of CsI was used to make a 1mM aqueous solution (Cs+: 130.1 ppm; I- :126.9 ppm). The outflow of the aqueous solution from the column was sampled at intervals of 2 days to calculate the average velocity and the permeability of the aqueous solution in the buffer medium. Concentration of Cs+ and I- in the effluent were also analyzed by ICP-MS and IC and the advection velocity, the dispersion coefficient and the retardation coefficient for Cs+ and I- were calculated from experimental results including the concentration breakthrough curves.
Quantitative information for the migration of radioactive nuclide in the buffer medium, acquired through experimental measurements, has been very rare both at home and aboard. Experimental results from this study were used as input parameter values for the numerical modeling to simulate the long-term radioactive nuclide migration in the buffer zone and to evaluate the feasibility of the buffer material, controlling the radioactive nuclide migration in the SNF repository site.
*This research was supported by Particulate Matter Management Specialized Graduate Program through the Korea Environmental Industry & Technology Institute (KEITI) funded by the Ministry of Environment (MOE).
In this study, the laboratory scale core (4.5 cm in diameter and 1.0 cm in length) experiments were performed to quantitatively investigate the migration properties of radioactive nuclides in the saturated compacted WRK-Bentonil. The syringe pump and high pressurized stainless-steel cell with dual outer wall were used to simulate the DGR environment (confining pressure: 5 MPa; injection pressure: 0.3-1.6 MPa; water saturation: 100%). The Cesium (Cs+) and Iodine (I-) were used as representative radioactive nuclides in this study and the powder type of CsI was used to make a 1mM aqueous solution (Cs+: 130.1 ppm; I- :126.9 ppm). The outflow of the aqueous solution from the column was sampled at intervals of 2 days to calculate the average velocity and the permeability of the aqueous solution in the buffer medium. Concentration of Cs+ and I- in the effluent were also analyzed by ICP-MS and IC and the advection velocity, the dispersion coefficient and the retardation coefficient for Cs+ and I- were calculated from experimental results including the concentration breakthrough curves.
Quantitative information for the migration of radioactive nuclide in the buffer medium, acquired through experimental measurements, has been very rare both at home and aboard. Experimental results from this study were used as input parameter values for the numerical modeling to simulate the long-term radioactive nuclide migration in the buffer zone and to evaluate the feasibility of the buffer material, controlling the radioactive nuclide migration in the SNF repository site.
*This research was supported by Particulate Matter Management Specialized Graduate Program through the Korea Environmental Industry & Technology Institute (KEITI) funded by the Ministry of Environment (MOE).