Geologic site characterization for deep nuclear waste disposal in fractured rock based on 3D data visualization

Three-dimensional (3D) visualization of data is an essential step in the development of descriptive hydrologic and rock-mechanical models of fractured rock systems. Data includes geological properties, rock mechanical properties and hydraulic responses. The 3D visualization approach is applied to characterizing a hypothetical site for a high-level nuclear waste repository located at 500 m depth in granitoids of the trans-Scandinavian igneous belt (1.6–1.8 Ga old). The study is based on site-specific data at the Äspö Hard Rock Laboratory (HRL) on the southeastern coast of Sweden. The data are extensive and spatially complex and are based on surface information, as well as a large number of boreholes penetrating up to 1000 m. At this site, fractures and fracture zones control both groundwater flow and mechanical stability. Structures are found within a 2×2×1 km deep model block representing the site. 3D locations of fractures and fracture zones are hypothesized based on surface and subsurface geological and geophysical information, including borehole radar. This results in a 3D geological model structure of the site.