An underground research tunnel (URT) is planned for construction at KAERI for the in situ studies related to the validation of a HLW disposal system. For the safe construction and long-term researches at the URT, the geological characteristics of the site were investigated and adequate design could be made. Mechanical stability analysis using a threedimensional analysis code with the rock mass properties determined from various tests was carried out. In the modeling, the actual topography, erosion effect, tunnel geometry and slope, sequential excavation, and geological conditions were considered. From the analysis, it was possible to predict the rock deformation, stress concentration, and plastic zone developed before and after the excavation.
The Korea Atomic Energy Research Institute (KAERI) is developing a disposal system for the permanent disposal of the spent fuel generated from 19 nuclear power plants in Korea. In order to develop a reasonable disposal system, it is necessary to validate the system in a rock similar to the host geological formation. In Korea, a small scale underground research tunnel (URT) for validating the design of the underground high-level waste (HLW) repository is being planned. The construction of the URT will be started in 2004 and completed in 2006. During the construction as well as after the construction, various in situ experiments related to the HLW disposal will be performed in the access tunnel and the research modules. The URT will be a major infrastructure for the HLW disposal program and be used for various in situ studies such as rock behavior, in situ stress change, influence of discontinuities, excavation disturbed zone (EDZ) study, fluid flow in rock mass, heater test at different scales, Thermo-Hydro-Mechanical (THM) experiment, generation and migration of colloids, and the validation of the processes for the transportation, emplacement, retrieval operation, and closure will be carried out. Research items which can be carried out at the URT are listed in Table 1.
