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Title: Rock-mass classification of candidate repository units at Yucca Mountain, Nye County, Nevada

Technical Report ·
OSTI ID:59837

The Nevada Nuclear Waste Storage Investigations (NNWSI) Project managed by the Nevada Operations Office of the Department of energy, is examining the feasibility of siting a repository for high-level radioactive waste at Yucca Mountain, a tuff site on and adjacent to the Nevada Test Site, Nye County, Nevada. Between 1981 and 1983, four tuff units were considered as potential units for emplacement of radioactive waste. Two of the four units are above the water table: the welded, devitrified portion of the Topopah Spring Member of the paintbrush Tuff and the zeolitized, nonwelded portion of the Tuffaceous Beds of Calico Hills. The other two units are below the water table: the welded, devitrified portion of the Bullfrog Member of the Crater Flat Tuff and the welded, devitrified portion of the Tram Member of the Crater Flat Tuff. In this study, available site-specific information from drillholes, supplemented by the needed information from tuff units at other locations, was used in conjunction with two rock-mass-classification systems to evaluate the relative excavation stability of these units. The two rock-mass-classification systems are the South African Council for Scientific and Industrial Research Classification System developed by Bieniawski and the Norwegian Geotechnical Institute Classification System developed by Barton. Two other tuff units located at Rainier Mesa on the Nevada Test Site, the welded portion of the Grouse Canyon Member of the Belted Range Tuff and the nonwelded Tunnel Bed 5, were also evaluated using these rock-mass-classification systems. These last two units were never considered as possible locations for waste emplacement but were evaluated as a basis for comparison with Yucca Mountain units because there are existing stable tunnels in the Rainier Mesa units.

Research Organization:
Sandia National Lab. (SNL-NM), Albuquerque, NM (United States); RE/SPEC, Inc., Rapid City, SD (United States)
DOE Contract Number:
AC04-76DP00789
OSTI ID:
59837
Report Number(s):
SAND-82-2034; ON: DE86008873
Resource Relation:
Other Information: PBD: Feb 1986
Country of Publication:
United States
Language:
English