Temperature, thermal conductivity, and heat flow near Yucca Mountain, Nevada: Some tectonics and hydrologic implications

Sass, J.H.; Lachenbruch, Arthur H.; Dudley, William W.; Priest, J.J.; Munroe, Robert J.

doi:10.3133/ofr87649

Cited by 58 publications

(94 citation statements)

References 1 publication

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“…In particular, the candidate repository site is within a local heat-flow low that extends from the vicinity of the large hydraulic gradient southward for about 10 km. The heat flows shown here (Figure 2) are from the unsaturated zone, but they are consistent with independent determinations in the saturated zone of drill holes that extend a significant distance below the water table and exhibit conductive thermal profiles [Sass et al, 1988].…”

Section: Thermal Structure Under Yucca Mountainsupporting

confidence: 68%

“…For example, there is a downward hydraulic gradient under northern Yucca Mountain, based on observations in drill hole USW G-2 [Czarnecki, 1994;Czarnecki et al, 1995]. Thermal observations suggest that this downward gradient extends to a depth of at least 1.3 km [Sass et al, 1988;Czarnecki et al, 1995]. An upward hydraulic gradient has been observed under southern Yucca Mountain in drill hole UE25-p#l; specifically, the head in the carbonate aquifer is about 20 m higher than that in the overlying tuff aquifer in this well [Craig and Robison, 1984].…”

Section: Hydrogeology Of Yucca Mountainmentioning

confidence: 99%

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On the mechanism of the large hydraulic gradient under Yucca Mountain, Nevada

Fridrich¹,

Ge²,

Sass³

1998

Open-File Report

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We use coupled fluid-and heat-flow modeling (the TOUGH2 code) to investigate three alternative hydrogeologic models for a steep 300-m water-table decline, known as the large hydraulic gradient (LHG), and a spatially coincident heat-flow low under Yucca Mountain, Nevada: (1) a fault-related dam within the volcanic tuff (water-table) aquifer, (2) a spillway created by abrupt southward increase in the depth-extent (thickness) and permeability of the tuff aquifer across a fault, and (3) a drain formed by a fault that allows the major flow through the tuff aquifer from the north to be captured by the underlying confined carbonate aquifer. All three models provide an adequate simulation of the observed water-table configuration under Yucca Mountain, as well as the shallow thermal regime. None of the models provides an adequate simulation of the deep thermal regime, and the drain model alone can be eliminated on that basis. Our simulations of the dam and spillway models yield strongly contrasting predictions about the pattern of vertical hydraulic gradients in the vicinity of the LHG, suggesting that a well-designed drilling and hydrologic testing program would yield definitive answers about the cause of this feature.

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Section: Thermal Structure Under Yucca Mountainsupporting

confidence: 68%

Section: Hydrogeology Of Yucca Mountainmentioning

confidence: 99%

On the mechanism of the large hydraulic gradient under Yucca Mountain, Nevada

Fridrich¹,

Ge²,

Sass³

1998

Open-File Report

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“…Measured temperature data (Sass et al, 1988;Rousseau et al, 1996) were compared with the 3-D simulation results for about 25 boreholes within and near the study area of the Yucca Mountain site. The 3-D model also uses the land surface and the water table as the top and bottom boundaries, with constant or spatially varying pressures, saturations and temperatures described based on the field data.…”

Section: Example 2 -Comparisons With Measured Temperature Profilesmentioning

confidence: 99%

On the effective continuum method for modeling multiphase flow, multicomponent transport, and heat transfer in fractured rock

Wu¹

2000

Dynamics of Fluids in Fractured Rock

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“…The initial estimates of temperature distributions at the bottom boundary, the water boreholes at an elevation of 730 masl [24,23]. Because the water table is not completely flat in the current UZ and TH models (See Figure 3), the actual estimates of the water …”

Section: Bottom-boundary Temperature Conditionmentioning

confidence: 99%

A mountain-scale thermal–hydrologic model for simulating fluid flow and heat transfer in unsaturated fractured rock

Mukhopadhyay

Zhang

et al. 2006

Journal of Contaminant Hydrology

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A multidimensional, mountain-scale, thermal-hydrologic (TH) numerical model is presented for investigating unsaturated flow behavior in response to decay heat from the radioactive waste repository in the Yucca Mountain unsaturated zone (UZ), Nevada. The model, consisting of both two-dimensional (2-D) and three-dimensional (3-D) representations of the UZ repository system, is based on the current repository design, drift layout, thermal loading scenario, and estimated current and future climate conditions. This mountain-scale TH model evaluates the coupled TH processes related to mountain-scale UZ flow. It also simulates the impact of radioactive waste heat release on the natural hydrogeological system, including heat-driven processes occurring near and far away from the emplacement tunnels or drifts. The model simulations predict thermally perturbed liquid saturation, gas-and liquid-phase fluxes, and water and rock temperature elevations, as well as the changes in water flux driven by evaporation/condensation processes and drainage between drifts. These simulations provide mountain-scale thermally perturbed flow fields for assessing the repository performance under thermal loading conditions. Key Words: thermal-hydrologic processes in subsurface, thermal load, Yucca Mountain, fluid and heat flow in porous media, heat pipe, reservoir simulation, fractured unsaturated rock * Corresponding author. Tel.: +1-510-486-7291; fax: +1-510-486-5686, E-Mail address: YSWu@lbl.gov. 2 IntroductionIn the past decade, the 500-700 m thick Yucca Mountain unsaturated zone (UZ) has been extensively investigated as a potential subsurface repository for storing high-level radioactive wastes. While the site characterization has been mostly carried out for analyzing unsaturated flow and radionuclide transport in ambient, isothermal conditions [30,31], the inherent nature of nonisothermal flow and transport processes, created by repository heating from radioactive decay, has also motivated many research efforts to understand thermal-hydrologic (TH) behavior and its impact on the repository performance within the UZ. In particular, significant progress has been made in quantitative TH modeling studies at Yucca Mountain [9,10,6].Emplacement of heat-generating high-level radioactive waste in the UZ system of unsaturated welded and unwelded fractured tuff at Yucca Mountain will perturb the ambient condition and create complex multiphase fluid flow and heat-transfer processes.The physical phenomena associated with repository heating include conduction and convection heat transfer, phase change (boiling and condensation), two-phase flow of liquid and gas phases under variably saturated conditions, enhanced fracture-matrix interaction caused by rapid matrix drying and subsequent imbibition, diffusion and dispersion of vapor and gas, and vapor-pressure-lowering effects. These TH processes will last hundreds to thousands of years after waste emplacement, and will significantly redistribute the in-situ moisture content and alter the per...

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Temperature, thermal conductivity, and heat flow near Yucca Mountain, Nevada: Some tectonics and hydrologic implications

Cited by 58 publications

References 1 publication

On the mechanism of the large hydraulic gradient under Yucca Mountain, Nevada

On the mechanism of the large hydraulic gradient under Yucca Mountain, Nevada

On the effective continuum method for modeling multiphase flow, multicomponent transport, and heat transfer in fractured rock

A mountain-scale thermal–hydrologic model for simulating fluid flow and heat transfer in unsaturated fractured rock

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