Variation of permeability with temperature in fractured Topopah Spring tuff samples

Conference · Thu Nov 01 00:00:00 EST 1990

OSTI ID:138000

Lin, Wunan

Fractures will play an important role in the near-field hydrology of a nuclear-waste package in a mined repository. Our previous studies showed that the water permeability of fractured Topopah Springs tuff samples decreased by more than three orders of magnitude when the sample`s temperature (in the case of a sample under a thermal gradient, the temperature in the hot zone) increased to 150{degree}C at a constant confining pressure of 5 MPa. When the fractured tuff samples were returned to room temperature the water permeability did not recover. We attributed the permeability decrease to smoothing of the asperities on the fracture surfaces, which was caused by the dissolution and redeposition of silica minerals as water flowed through the sample. Water permeability of an intact tuff sample did not change significantly under similar experimental conditions. In this study, a fractured Topopah Spring tuff sample was used to determine the variation of nitrogen (N{sub 2}) permeability with increasing temperature at a constant confining pressure of 5 MPa under the following conditions: dry sample, sample saturated with standing water, and steam flowing through the sample. The N{sub 2} permeability of a dry fractured tuff sample was independent of temperature. The water permeability measured at room temperature before and after the sample was heated to 150{degree}C with standing water did not change either. On the other hand, flowing steam through the sample at 127{degree}C for about one week decreased the N{sub 2} permeability by more than one order of magnitude. Apparently flowing steam and flowing water have a similar effect on smoothing the asperities of the fracture surfaces. 8 refs., 4 figs., 1 tab.

• Research Organization: Lawrence Livermore National Lab. (LLNL), Livermore, CA (United States)
• DOE Contract Number: W-7405-ENG-48
• OSTI ID: 138000
• Report Number(s): UCRL-JC-104765; CONF-910435-16; ON: DE91005186; TRN: 91:004778
• Resource Relation: Conference: 2. annual American Nuclear Society (ANS) international high level radioactive waste management conference, Las Vegas, NV (United States), 28 Apr - 3 May 1991; Other Information: PBD: Nov 1990
• Country of Publication: United States
• Language: English

Related Subjects

05 NUCLEAR FUELS
54 ENVIRONMENTAL SCIENCES
TUFF
PERMEABILITY
WATER
NITROGEN
HIGH-LEVEL RADIOACTIVE WASTES
WASTE-ROCK INTERACTIONS
RADIOACTIVE WASTE MANAGEMENT
ROCK-FLUID INTERACTIONS
TEMPERATURE DEPENDENCE
FRACTURES
YUCCA MOUNTAIN
HYDROLOGY
FLUID MECHANICS
HYDRAULICS
FLUID FLOW
GEOLOGIC FRACTURES
Yucca Mountain Project