Three-dimensional numerical simulation of groundwater flow, salt and radionuclide transport at a proposed radioactive waste disposal site in Gyeongju, Republic of Korea

A series of steady-state and transient-state three-dimensional numerical simulations and calibration using a generalized multidimensional multicomponent hydrodynamic dispersion model is performed to predict and analyse groundwater flow and both salt and radionuclide transport at a proposed low and intermediate level radioactive waste disposal site, in Gyeongju, Republic of Korea. The results of the numerical simulations show that the hydrogeological characteristics of each anisotropic geological formation (porous rock matrix plus joint sets) are more dependent on the joint sets than the porous rock matrix, while the hydrogeological characteristics of the whole geological system (geological formations plus fracture zones) are even more controlled by the fracture zones than the geological formations. The results of the numerical simulations also indicate that both adsorption (retardation) and radioactive decay of the radionuclides play important roles in maximizing the efficacy of the surrounding geological formations as natural barriers and thus in minimizing the dispersion of the mother and daughter radionuclides from the proposed repository.