The advection in the crack and the diffusion from the crack surface to rock matrix of contaminated materials in a rock mass are one of the important factors to evaluate the characteristics of the rock mass as a natural barrier function for a radioactive waste disposal project.
In this study, X-ray CT method was applied to evaluate the advection in the crack and the diffusion of solute from the crack surfaces to the rock matrix. In order to visualize advection and diffusion phenomena, the tracer migration tests have been applied to the porous sandstone and the tracer migration and diffusion process was visualized by X-ray CT scanner. In order to evaluate density distribution in the crack and pores in the rock matrix, advanced coefficient of tracer density increment was defined. In this study, the relations between the flow in the crack and the amount of the diffused tracer into the rock matrix were discussed. The influences of the crack aperture to the tracer diffusion process were also discussed.
