Geological Mapping Approach and Method for Assessing Suitability of Crystalline Rocks for Hosting Canada's Deep Geological Repository for Used Nuclear Fuel

Abstract

The Nuclear Waste Management Organization (NWMO) is currently conducting initial field studies in a number of communities participating in a site selection process to find an informed and willing community to host Canada’s deep geological repository for used nuclear fuel. Initial field studies involve activities such as high resolution airborne geophysical surveys and direct mapping observations. These field activities are designed to further advance understanding of the geology of the areas being studied, building on previously conducted desktop studies. Consistent with NWMO’s approach, all field activities are planned and conducted with the involvement and collaboration of the communities and Aboriginal peoples. This paper focusses on the approach, tools and techniques used to plan and conduct geological mapping in crystalline rocks of the Canadian Shield. A description of the site evaluation process and approach used to conduct and analyze high resolution airborne surveys areprovided in twocompanion papers.The main objective of geological mapping is to further advance understanding of the geological suitability of the various communities being assessed. This involves understanding of the rock type, and the structural character of the bedrock, especially the size, frequency, type and location of fractures. An initial walking of the land using existing roads and trails is conducted to map rock outcrops to observe and understand general geological features. This is followed by detailed geological mapping where the intent is to map as many rock outcrops as possible within the areas of interest. Fieldwork planning involves the analysis of existing relevant datasets including historical bedrock and Quaternary maps, high resolution imagery, road networks and lineament interpretations from remotely sensed geophysical and imagery datasets. Another valuableplanning activity is to perform remote predictive modeling using specialized software and satellite imagery to identify potential locations of rock outcrops.