Seepage into an Underground Opening Constructed in Unsaturated Fractured Rock Under Evaporative Conditions

Trautz, R. C. ; Wang, Joseph S. Y.

United States. Department of Energy. Yucca Mountain Project Office.

关键词: 12 Management Of Radioactive Wastes, And Non-Radioactive Wastes From Nuclear Facilities;    Evaporation;    Underground Facilities;    Yucca Mountain;    Water Influx;   

DOI  :  10.2172/787041
RP-ID  :  NONE
RP-ID  :  NONE
RP-ID  :  787041

美国|英语

来源: UNT Digital Library

【 摘 要 】

Liquid-release tests, performed in boreholes above an underground opening constructed in unsaturated fractured rock, are used in this study to evaluate seepage into a waste emplacement drift. Evidence for the existence of a capillary barrier at the ceiling of the drift is presented, based on field observations (including spreading of the wetting front across the ceiling and water movement up fractures exposed in the ceiling before seepage begins). The capillary barrier mechanism has the potential to divert water around the opening, resulting in no seepage when the percolation flux is at or below the seepage threshold flux. Liquid-release tests are used to demonstrate that a seepage threshold exists and to measure the magnitude of the seepage threshold flux for three test zones that seeped. The seepage data are interpreted using analytical techniques to estimate the test-specific strength of the rock capillary forces ({alpha}{sup -1}) that prevent water from seeping into the drift. Evaporation increases the seepage threshold flux making it more difficult for water to seep into the drift and producing artificially inflated {alpha}{sup -1} values. With adjustments for evaporation, the minimum test-specific threshold is 1,600 mm/yr with a corresponding {alpha}{sup -1} of 0.027 m.