Geological and Hydrogeological Evaluations of Field Conditions for In-DEBS Test

In order to understand behaviors of engineered barriers for geological disposal of high-level radioactive wastes, an In-DEBS (In-situ Demonstration of Engineered Barrier System) test was planned. Geological and hydrogeological data of KURT (KAERI Underground Research Tunnel) site were obtained and analyzed to select an appropriate position for the In-DEBS test. Proper research galleries in the extended section of KURT were decided on for the test using regional data of the KURT site. Borehole investigations were carried out to examine local properties of the research galleries in order to characterize groundwater flow and evaluate groundwater inflow at the research galleries. The data from the borehole investigations provided the basis for selecting the position of a large-diameter borehole for the In-DEBS test as well as other practical requirements for implementing the test in the KURT conditions. From in-situ investigation of a wall of the large-diameter borehole, groundwater inflow and distribution of hydraulic conductivity at the wall were evaluated. The hydrogeological data and analysis results in this study can be applied to understand and simulate the evolution of the behavior of In-DEBS and nearby rocks.