Development of three dimensional geologic model for nuclear deep geologic repositories in crystalline rocks in Korea

A three dimensional (3D) geological model is developed for nuclear deep geological repositories (DGR) in crystalline rocks in Korea. The research includes integration of site descriptive modelling (SDM) with the 3D geological model. Thus the research will serve as a platform for various disciplines related to disposal. This is part of 9 year research project of safety case development for DGR in Korea for high-level nuclear waste.

We have adopted SKUA-GOCAD for building the 3D geological model, since the software provides excellent interpolation function for constructing geological boundaries. A testbed with the geology of crystalline rocks was selected for the 3D modelling. The geology consists of Precambrian basement, Permian to Cretaceous sedimentary cover rocks and Mesozoic granitoids. Since the geologic boundaries of the basement and the granitoids are irregular in shape, the structural and stratigraphic model in SKUA-GOCAD is difficult to apply for the formation of geologic boundaries. We have adopted point cloud methods to form the irregular geologic boundaries. The primary data for our 3D geologic model is the geologic boundaries on maps and cross sections. Then the geologic boundaries are adjusted with borehole data and geophysical data.

A relational database for SDM data with coordinate information is under development. These data share the database primary key with geologic domains and subdomains. The data table allows handling multiple spatial types (point, surface and volume) and physical quantities (scalar, vector, tensor). A visualization tool is also under development. The tool displays SDM data along with geologic elements. Drill core trajectories and the results of geophysical survey can be displayed in linear, surficial and volumetric form.