The US Department of Energy (DOE) and its predecessor agencies are responsible for nuclear weapons research and development as part of the national defense program. These activities include underground nuclear testing, and a small number of such tests have been conducted at sites distant from the Nevada Test Site (NTS). An NTS site-wide Environmental Impact Statement (EIS) is being prepared in 1995 and includes the two offsite test areas in Nevada: the Shoal site and the Central Nevada Test Area. At the time of these tests, evaluations of project safety and predictions of groundwater transport of contaminants were made, and the tests were deemed safe to the public. These early evaluations were not considered sufficient for the EIS, so DOE decided to perform a new exposure assessment for the Shoal site. The basic scenario evaluated for this exposure assessment is transport of tritium from the Shoal underground nuclear test by groundwater to a receptor well where an individual drinks the contaminated water for 70 years, centered around the time of peak tritium concentration. This scenario is entirely hypothetical because, as of 1995, there are no known occurrences of humans drinking water downgradient from the test. Four specific scenarios are analyzed because of uncertainty in flowpath direction. Two of these presume that wells are drilled at the boundary of the current DOE land withdrawal and are then used for drinking water supply. Wells do not currently exist at these locations and thus the resultant risks do not apply to any current populations; however, there are no controls to prevent such wells from being drilled in the future. The two other scenarios consider transport to the first existing wells along possible flowpaths. These wells are currently used only seasonally to water cattle, and as such, these risks also do not apply to current populations.