Yucca Mountain is a remote desert location used for military purposes
Yucca Mountain is part of an isolated, unpopulated desert region in Nevada. It is on the western border of the Nevada test site, where over 900 nuclear weapons were detonated, most underground, from the dawn of the atomic age until about ten years ago. This area of Nevada is still actively used by the U.S. military.

Among the most comprehensive scientific investigations ever conducted
The intensive scientific study of Yucca Mountain's suitability as a national used nuclear fuel repository—called "site characterization"—has been undertaken to assess the capability of the natural features at Yucca Mountain to safely contain radioactive waste. Yucca Mountain site characterization is one of the most thorough scientific studies ever performed, lasting years, costing more than $6 billion and involving thousands of scientists, engineers and technicians.

Initial delay of Yucca Mountain site characterization
The start of site characterization was delayed for several reasons, among them the refusal of Nevada to issue the environmental permits needed for surface-disturbing work, such as maintaining roads, digging trenches and drilling boreholes. By mid-1992, following several court cases involving the U.S. Department of Energy and Nevada, the state had issued the needed permits and a full-scale study of the site began with no further interruption.

Surface-based investigations of Yucca Mountain mostly completed
For Yucca Mountain site characterization, a specially developed rig that can drill to a depth of 3,500 feet has drilled three deep boreholes. Since the rig uses no drilling fluids, samples are clean of materials that might otherwise be introduced by drilling. Other activities include the digging of test pits for use in volcanism studies, the completion of trenching to gather data on potential geologic faulting in the area, and drilling of more than 20 shallow boreholes to study rainwater infiltration.

Underground Exploratory Studies Facility constructed inside Yucca Mountain
In 1994, using a tunnel boring machine, DOE began constructing a system of tunnels that will allow scientists to conduct seismological, geological and hydrological studies—known as the Exploratory Studies Facility. The five-mile tunnel was completed in 1997. Since then, scientists have expanded tests in the tunnel and its numerous niches and alcoves to study the reaction of rock and the movement of water through the rocks to the heat released by used nuclear fuel in a repository. The data from these tests will help scientists design the repository and assess its performance.

Cross-drift tunnel constructed to expand internal Yucca Mountain studies
In 1998, DOE excavated a new tunnel, or cross-drift, more than a mile inside the existing tunnel. The cross-drift cuts 1.7 miles through all the rock layers of the potential repository section, allowing scientists and engineers to examine and test the rocks that make up the potential repository.

Full array of scientific apparatus deployed, data collected and analyzed
Since completing a 1.7-mile cross-drift tunnel spanning the entire planned width of the proposed repository in 1998, DOE has deployed a comprehensive array of scientific apparatus sufficient to complete its characterization of the site and prepare for a possible site recommendation decision at the end of 2001. DOE's scientific instruments have extracted a wealth of additional data from hundreds of tunnel alcoves, tunnel niches, and boreholes in the repository rock as well as from a number of surface locations. The enhanced knowledge of the repository gained over these past 3 years has led to a significant refinement of DOE's performance assessment of Yucca Mountain since the 1998 viability assessment. This latest information has strengthened scientific confidence in the repository's ability to protect public health and safety, while uncovering no reason why used nuclear fuel and defense high-level radioactive waste should not be permanently disposed of in Yucca Mountain.

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