THE ROAD TO YUCCA MOUNTAIN: A BRIEF HISTORY

After the failure of the Lyons, Kansas salt deposit as a potential high-level nuclear waste (HLW) site in 1971, the AEC (now the DOE) broadened its search to include other geologic environments. USGS scientists with regional and topical expertise assisted DOE and its contractors in this screening effort, eventually documenting its earth-science perspectives in 1978 in USGS Circular 779 and in an interagency Earth Science Technical Plan. USGS also received direct appropriations from 1979 until 1992 to conduct topical and regional hydrogeologic studies relevant to HLW disposal. These included an assessment of the suitability for repositories of the Basin and Range province in seven western states, including Nevada and California in the Death Valley region. In consultation with the affected state geological agencies, the USGS documented its screening results in six Professional Papers.

In a parallel course of events, USGS Director V.E. McKelvey proposed in 1976 to DOE's predecessor that the Nevada Test Site be given high priority among possible repository sites because of its potentially favorable geology and hydrology, which already were well documented from USGS studies for nuclear-weapons tests. By 1982, the saturated zones at Yucca Mountain and at sites in Texas and Washington were all under consideration, but Yucca Mountain was problematic because of large fracture permeability and high temperature beneath the deep water table. However, it did have potential for a repository within its thick unsaturated zone (UZ), an environment proposed for HLW disposal by I.J. Winograd of USGS, who published papers on this concept in 1974 and 1981. In 1982, DOE concurred with a USGS advisory letter and redirected Yucca Mountain studies to the UZ. A detailed conceptual study of a repository in the Yucca Mountain UZ, USGS Circular 903 by E.H. Roseboom, quickly followed.

NRC’s 10 CFR Part 60 technical criteria for a repository in the saturated zone was released in 1983. It stated that UZ criteria would be proposed. NRC’s NUREG 1046 summarized the changes proposed by USGS and DOE. With many references to Circular 903, NRC released the final criteria in 1985. After the final amendment of the Nuclear Waste Policy Act in 1988 eliminated all other sites, the NRC established 10 CFR Part 63 specifically for the Yucca Mountain UZ.