Three-Dimensional Geologic Modeling of a Prospective Deep Underground Laboratory Site for High-Level Radioactive Waste Disposal in Korea

Abstract:

A series of three-dimensional geologic modeling was performed using a geostatistical geologic model GOCAD (ASGA and Paradigm) to characterize quantitatively and to visualize realistically a prospective deep underground laboratory site for high-level radioactive waste disposal in Korea. The necessity of a deep underground laboratory arises from its in-situ conditions for related deep scientific experiments. However, the construction and operation of such a deep underground laboratory take great efforts and expenses owing to its larger depth and thus higher geologic uncertainty. For these reasons, quantitative characterization and realistic visualization of geologic formations and structures of a deep underground laboratory site is crucial before its construction and operation. The study area for the prospective deep underground laboratory site is mainly consists of Precambrian metamorphic rocks as a complex. First, various topographic and geologic data of the study area were collected from literature and boreholes and preliminarily analyzed. Based on the preliminary analysis results, a three-dimensional structural model, which consists of the boundaries between the geologic formations and structures, was established, and a three-dimensional grid model, which consists of hexahedral grid blocks, was produced. Three-dimensional geologic formation model was then established by polymerizing these two models. Finally, a series of three-dimensional lithofacies modeling was performed using the sequential indicator simulation (SIS) and truncated Gaussian simulation (TGS). The volume fractions of metamorphic rocks predicted using the TGS are more similar to the actual data observed in boreholes than those predicted using the SIS. These three-dimensional geologic modeling results can improve a quantitative and realistic understanding of geologic characteristics of the prospective deep underground laboratory site for high-level radioactive waste disposal and thus can provide practical guidelines for its precise construction and safe operation. This work was supported by the Radioactive Waste Management Program funded by the Korea Institute of Energy Technology Evaluation and Planning (KETEP), Ministry of Trade, Industry and Energy, Republic of Korea.