EVALUATION OF GEOLOGIC OPTIONS FOR DISPOSAL OF HIGH-LEVEL RADIOACTIVE WASTE USING A GIS DATABASE

Experiences in the United States and elsewhere have shown that successfully siting a high-level radioactive waste repository is one of the biggest challenges facing a nuclear waste program. Only a few countries have progressed to the point of selecting a specific repository site. Studies of potential host rocks in the United States started in the 1950s and included several types of sedimentary and crystalline rock. Once again, these options are being evaluated through research supported by the DOE Office of Nuclear Energy’s Used Fuel Disposition Campaign. To support a better understanding of the distribution of alternative host rocks and potential siting issues, we are building a geographic information system (GIS) database for the three alternative geologic host rocks being considered for mined repositories (granitic, salt and clay-bearing rocks) and crystalline (granitic) basement for deep borehole disposal. No computer-based geologic database has previously existed to evaluate nuclear waste disposal options at the national scale that includes alternative host rocks. Data for areal extent, depth and thickness of major shale, salt and granitic rock formations in the contiguous U.S. are being obtained from a variety of sources, either as digital data files or from maps and figures that we digitize for inclusion in the database. The database also incorporates other information such as geologic hazards, natural resources and cultural features, all of which could potentially impact site screening and selection. We are currently focused on documenting and analyzing depth and thickness data to identify host-rock formations that could reasonably host a geologic repository. When complete, the database will provide a modern GIS-based framework to support future siting decisions in the U.S.