Geochemical homogeneity of tuffs at the potential repository level, Yucca Mountain, Nevada

Conference · Sun Apr 29 04:00:00 EDT 2001

OSTI ID:794103

Peterman, Zell E ^[1]; Cloke, Paul

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1. USGS

In a potential high-level radioactive waste repository at Yucca Mountain, Nevada, radioactive waste and canisters, drip shields protecting the waste from seepage and from rock falls, the backfill and invert material of crushed rock, the host rock, and water and gases contained within pores and fractures in the host rock together would form a complex system commonly referred to as the near-field geochemical environment. Materials introduced into the rock mass with the waste that are designed to prolong containment collectively are referred to as the Engineered Barrier System, and the host rock and its contained water and gases compose the natural system. The interaction of these component parts under highly perturbed conditions including temperatures well above natural ambient temperatures will need to be understood to assess the performance of the potential repository for long-term containment of nuclear waste. The geochemistry and mineralogy of the rock mass hosting the emplacement drifts must be known in order to assess the role of the natural system in the near-field environment. Emplacement drifts in a potential repository at Yucca Mountain would be constructed in the phenocryst-poor member of the Topopah Spring Tuff which is composed of both lithophysal and nonlithophysal zones. The chemical composition of the phenocryst-poor member has been characterized by numerous chemical analyses of outcrop samples and of core samples obtained by surface-based drilling. Those analyses have shown that the phenocryst-poor member of the Topopah Spring Tuff is remarkably uniform in composition both vertically and laterally. To verify this geochemical uniformity and to provide rock analyses of samples obtained directly from the potential repository block, major and trace elements were analyzed in core samples obtained from drill holes in the cross drift, which was driven to provide direct access to the rock mass where emplacement drifts would be constructed.

• Research Organization: U.S. Geological Survey, Denver, CO (US); Science Applications International Corp., Las Vegas, NV (US)
• Sponsoring Organization: US Department of Energy (US)
• DOE Contract Number: AI08-97NV12033
• OSTI ID: 794103
• Country of Publication: United States
• Language: English

Related Subjects

11 NUCLEAR FUEL CYCLE AND FUEL MATERIALS
12 MANAGEMENT OF RADIOACTIVE AND NON-RADIOACTIVE WASTES FROM NUCLEAR FACILITIES
CHEMICAL COMPOSITION
CONTAINMENT SYSTEMS
DRILL CORES
GEOCHEMICAL
GEOCHEMISTRY
HIGH-LEVEL RADIOACTIVE WASTES
LEVEL
RADIOACTIVE WASTE FACILITIES
REPOSITORY
SITE CHARACTERIZATION
TRACE AMOUNTS
TUFF
TUFFS
WASTES
YUCCA MOUNTAIN