ABSTRACT
The Yucca Mountain Project, managed by the Nevada Operations Office of the U. S. Department of Energy, is examining the feasibility of siting a repository for high-level nuclear waste at Yucca Mountain, on and adjacent to the Nevada Test Site. The proposed repository will be excavated in the Topopah Spring Member, which is a moderately fractured, unsaturated, welded tuff. Excavation stability will be required during construction, waste emplacement, retrieval, and closure to ensure worker safety. Analyses of drift stability are required to assess the acceptable waste emplacement density, to design the drift shapes and ground support systems, and to establish schedules and cost of construction. Drift design criteria are established from the regulatory requirements, drift performance goals, and materials performance. The example application is for a waste emplacement drift with waste emplaced in a vertical borehole in the floor of the room.
