Thermal loading studies using the Yucca Mountain unsaturated zone model

Haukwa, C.; Wu, Yu‐Shu; Bodvarsson, G.S.

doi:10.1016/s0169-7722(99)00016-9

Cited by 23 publications

(23 citation statements)

References 27 publications

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“…Numerical grids were generated based on an integral finite-difference scheme [15] with an irregular, unstructured, control-volume spatial discretization. and matrix representation; (2) the effective continuum method [9]; and (3) the dualcontinuum method, including double-and multiporosity, DKM, or the more general "multiple interacting continua" method [18]. Different modeling approaches have been tested for handling fracture-matrix interaction at Yucca Mountain [7].…”

Section: Numerical Model Gridsmentioning

confidence: 99%

“…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]. …”

Section: Introductionmentioning

confidence: 99%

“…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%

“…For large, mountain-scale multidimensional modeling exercises, the effective continuum model (ECM), rather than the more rigorous DKM (dual-permeability) approach [17], has often been resorted to in these studies [29,9]. This choice primarily results from the numerical difficulty and computational intensity involved in solving highly nonlinear coupled twophase fluid flow and heat transfer under boiling conditions in unsaturated fractured rock.…”

Section: Introductionmentioning

confidence: 99%

“…In particular, fracture-matrix rock properties and other model parameters have been better estimated and updated. In addition, the repository design and drift layout plans have also been revised, which are different from the ones used in previous TH modeling studies [9,10]. Since the objective of this paper is to develop a fully coupled mountain-scale TH model that incorporates the-state-of-the-art information about the hydrogeology of the Yucca Mountain site, the above advances in site characterization, data collection, parameter estimates, and repository redesign have been included in developing the TH model in this paper.…”

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confidence: 99%

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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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Section: Numerical Model Gridsmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

mentioning

confidence: 99%

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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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Modelling groundwater flow changes due to thermal effects of radioactive waste disposal at a hypothetical repository site near Sellafield, UK

et al. 2015

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High-level radioactive waste (HLW) and spent fuel from nuclear power plants (SF) require very long duration disposal because of its long-lived toxicity. Specific repository design is necessary to accommodate the associated large heat generation from continual decay. Conceptual designs propose geological containment within salt, claystone, or crystalline bedrock. However, while many studies have investigated the safety of disposal in these host rocks, the interaction of near-field heat coupled to far-field groundwater flow for UK-relevant conditions has not been fully investigated. Using an excellent dataset from a repository investigation in saturated fractured rock at Sellafield, UK, with deep groundwater flow, a preliminary investigation of the effect of the addition of heat from HLW and SF on regional groundwater flow is undertaken. A coupled thermohydrogeological groundwater flow model dependent on fluid density and viscosity has been calibrated to field data, before heat is added to simulate waste. Substantial heating reduces fluid density and dynamic viscosity. Groundwater flows upwards through permeable damage zones of high-angle faults and increases natural velocity by 1.59. Elevated groundwater temperatures are predicted at the surface in just hundreds of years. Travel times for conservative chemical species from the hypothetical repository to the St. Bees Sandstone aquifer are reduced by over one-third if engineered barriers fail at the point of containment, and remain reduced by hundreds of years for particles released thousands of years after containment. The results imply that in conditions similar to those modelled, the high-performance guarantee of the engineered barrier is essential to repository safety. A very good understanding of the coupled interaction of near-field heat and far-field groundwater flow will be important for safety cases, especially accuracy concerning heterogeneous fault discontinuities. It is necessary to model heat advection and faults at fractured sites.

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Conceptual model for flow separation processes affecting waste package chemical environment, Yucca Mountain, Nevada

Hall

Walton

2006

Applied Geochemistry

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Thermal loading studies using the Yucca Mountain unsaturated zone model

Cited by 23 publications

References 27 publications

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

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

Modelling groundwater flow changes due to thermal effects of radioactive waste disposal at a hypothetical repository site near Sellafield, UK

Conceptual model for flow separation processes affecting waste package chemical environment, Yucca Mountain, Nevada

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