Overview of scientific investigations at Yucca Mountain—the potential repository for high-level nuclear waste

The US Department of Energy (DOE) has been evaluating the unsaturated zone (UZ) at Yucca Mountain, Nevada, as a potential repository site for high level nuclear waste. A large number of boreholes have been drilled at the site, and an underground tunnel, the exploratory studies facility (ESF), has been constructed. A variety of boreholes and underground tests have been conducted that have provided large amounts of data from the UZ. This paper summarizes some of the current knowledge of geological and hydrological characteristics of the site and provides the framework for a series of technical papers that follow in this issue. A brief discussion is also given to the repository safety strategy for Yucca Mountain and the UZ site-scale flow model.