A study of thermally induced convection near a high‐level nuclear waste repository in partially saturated fractured tuff

Tsang, Yvonne; Pruess, Karsten

doi:10.1029/wr023i010p01958

Cited by 74 publications

(41 citation statements)

References 16 publications

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“…As an example, Figure 4 shows a diagram of a schematic two-dimensional axisymmetric model of a repository in the unsaturated zone at Yucca Mountain. From numerical simulations it was predicted that the repository heat load would induce significant thermal buoyancy now in the gas phase, with typical pore velocities of order to -100 m/year ( [20]; see Figure 5). This raises concerns about the potential release of gaseous contaminants, such as C-14 in the form of carbon dioxide [21].…”

Section: Applicationsmentioning

confidence: 99%

Modeling Studies of Multiphase Fluid and Heat Flow Processes in Nuclear Waste Isolation

Pruess

1988

MRS Proc.

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Multiphase fluid and heat flow plays an important role in many problems relating to the disposal of nuclear wastes in geologic media. Examples include boiling and condensation processes near heat-generating wastes, flow of water and formation gas in partially saturated formations, evolution of a free gas phase from waste package corrosion in initially water-saturated environments, and redistribution (dissolution, transport, and precipitation) of rock minerals in non-isothermal flow fields. Such processes may strongly impact upon waste package and repository design considerations and performance.This paper summarizes important physical phenomena occurring in multiphase and nonisother-mal flows, as well as techniques for their mathematical modeling and numerical simulation. Illustrative applications are given for a number of specific fluid and heat flow problems, including: ther-mohydrologic conditions near heat-generating waste packages in the unsaturated zone; repository-wide convection effects in the unsaturated zone; effects of quartz dissolution and precipitation for disposal in the saturated zone; and gas pressurization and flow effects from corrosion of low-level waste packages.

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Section: Applicationsmentioning

confidence: 99%

Modeling Studies of Multiphase Fluid and Heat Flow Processes in Nuclear Waste Isolation

Pruess

1988

MRS Proc.

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“…Because of the large spatial and temporal scales involved in such characterization, quantitative modeling 3 evaluation of the coupled fluid-flow and heat-transfer processes has proven to be essential. Quantitative investigation of TH processes at the Yucca Mountain repository site have motivated a continual effort to develop and apply different scale fluid and heat flow models [25,20,21,19,5,29,26,9,10,1,6,13,14,2]. These numerical models have played a crucial role in understanding coupled fluid and heat flow as well as in assessing how TH conditions affect on various aspects of the overall UZ waste disposal system.…”

Section: Introductionmentioning

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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“…Heat-driven vapor movement can also be significant on the repository scale (Travis et al, 1984;Pollock, 1986;Tsang and Pruess, 1987). The buoyancy mechanism is driven by fluid density differences associated with thermal expansions.…”

Section: -8mentioning

confidence: 99%

Processes, mechanisms, parameters, and modeling approaches for partially saturated flow in soil and rock media; Yucca Mountain Site Characterization Project

Wang¹,

Narasimhan²

1993

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A study of thermally induced convection near a high‐level nuclear waste repository in partially saturated fractured tuff

Cited by 74 publications

References 16 publications

Modeling Studies of Multiphase Fluid and Heat Flow Processes in Nuclear Waste Isolation

Modeling Studies of Multiphase Fluid and Heat Flow Processes in Nuclear Waste Isolation

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

Processes, mechanisms, parameters, and modeling approaches for partially saturated flow in soil and rock media; Yucca Mountain Site Characterization Project

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