An interim report on excavation effect studies at the Waste Isolation Pilot Plant: The delineation of the disturbed rock zone

Technical Report · Thu Sep 01 04:00:00 EDT 1988

OSTI ID:6783903

Borns, D J; Stormont, J C

For nuclear waste repositories with both long operational periods (50 yr) and long performance assessment periods (10,000 yr), the Disturbed Rock Zone (the zone of rock in which the mechanical and hydrologic properties have changed in response to excavation; abbreviated as DRZ) is important to both operational (e.g., slab or fracture failure of the excavation) and long term performance (e.g., seal system performance and fluid transport). At the Waste Isolation Pilot Plant (WIPP), the DRZ has been characterized with three approaches: visual observation; geophysical methods; and permeability measurements. Visual observations in drillholes indicate that fluids and fractures are common in the host rock of the underground facility. Geophysical studies have utilized radar, electromagnetic (EM), and direct current (DC) electromagnetic methods. Radar has been useful, but the penetration is limited by the water content and bedded nature of the host rock. The EM method was able to detect a fourfold increase in resistivity from 1 to 5 m into the rock. This trend reflects a fourfold increase in the moisture content from near the excavation (0.5 to 1% by weight) to 5 m into the host rock (2 to 3% by weight). The DC method has been able to detect zones of moisture around the excavation. Numerous gas permeability measurements indicate that beyond 2 m from an excavation halite and interbeds (anhydrite and clay) allow very low gas flow (calculated permeabilities <1 microdarcy for gas flow tests and <0.01 microdarcy for brine based permeability tests). Within 2 m of the excavation, very high flow rates (10/sup 4/ SCCM) were measured. All three approaches have defined a DRZ at the WIPP extending laterally throughout the excavation and varying in depth from 1 to 5 m, according to the size and age of the opening. 29 refs., 11 figs., 1 tab.

• Research Organization: Sandia National Labs., Albuquerque, NM (USA)
• DOE Contract Number: AC04-76DP00789
• OSTI ID: 6783903
• Report Number(s): SAND-87-1375; ON: DE89000626
• Country of Publication: United States
• Language: English

Related Subjects

052002* -- Nuclear Fuels-- Waste Disposal &amp; Storage
053000 -- Nuclear Fuels-- Environmental Aspects
11 NUCLEAR FUEL CYCLE AND FUEL MATERIALS
12 MANAGEMENT OF RADIOACTIVE AND NON-RADIOACTIVE WASTES FROM NUCLEAR FACILITIES
ALPHA-BEARING WASTES
BRINES
EVALUATION
FUNCTIONAL MODELS
GEOLOGIC STRUCTURES
GEOPHYSICS
HIGH-LEVEL RADIOACTIVE WASTES
MANAGEMENT
MATERIALS
MEASURING INSTRUMENTS
MECHANICS
NATIONAL ORGANIZATIONS
NUCLEAR FACILITIES
PERMEABILITY
PILOT PLANTS
RADAR
RADIOACTIVE MATERIALS
RADIOACTIVE WASTE FACILITIES
RADIOACTIVE WASTES
RANGE FINDERS
ROCK MECHANICS
SHAFT EXCAVATIONS
UNDERGROUND DISPOSAL
UNDERGROUND FACILITIES
US DOE
US ORGANIZATIONS
WASTE DISPOSAL
WASTE MANAGEMENT
WASTES
WIPP