Tectonic stability aspects of high-level radioactive waste repository siting and licensing

Tectonic stability implies the relative absence of tectonic activity, such as earthquakes, volcanism, uplift and subsidence. Long-term tectonic stability is an important consideration for licensing of a mined geologic repository for containment of high-level radioactive waste. Stability is needed to insure that the repository system is not breached in such a way as to shorten the flow path or to increase the rate of transport of radionuclides to the biosphere (accessible environment). The effects of tectonic activity that should be considered during siting, design and licensing of a repository include: changes in the groundwater regime by ground movement, disruption of the repository and design features by vibratory ground motion during seismic events, rupture of natural and engineered barriers by faulting, and disruption of the repository or hydrologic regime by volcanic activity. The potential for each of these events is dependent upon the tectonic environment in the area of a repository site. Careful siting investigations, detailed site characterization studies, and design studies are required to minimize the potential problems from any of these tectonic activities