Abstract
For the geological disposal of high level radioactive wastes, an excavation damaged zone (EDZ) adjacent to the tunnels will be the potential pathways for radioactive contaminant transport, having a high hydraulic conductivity due to the fractures in a rock. The potential pathways will be sealed by the engineered barriers, that is, a combination of tunnel plug, backfill and grouting, the material for which would be a clay-based mixture upon consideration of the long-term stability of the seals. Clay-based grout is one of the effective method to interrupt the migration of radionuclides through the EDZ.
The application of clay-based grout using bentonite to sealing the EDZ was tested around the tunnel in the granitic rock and the modeling of a reduction of permeability was carried out based on the results of the in-situ test. The filtration model of bentonite slurry could describe the results of the in-situ test and the modeling indicated that there was the most effective concentration to reduce the permeability of EDZ.
