Coupled thermal–hydrological–mechanical analyses of the Yucca Mountain Drift Scale Test—Comparison of field measurements to predictions of four different numerical models

Rutqvist, Jonny; Barr, D.; Datta, Robin N.; Gens, Antonio; Millard, Alain; Olivella, S.; Tsang, Chin‐Fu; Tsang, Yvonne

doi:10.1016/j.ijrmms.2005.03.008

Cited by 99 publications

(65 citation statements)

References 13 publications

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“…This modeling work has greatly enhanced our understanding of the coupled near-field processes in two different rock formations (crystalline rock versus volcanic tuff), hydrological settings (saturated versus unsaturated), and emplacement designs (backfilled drift versus open drift), and has added confidence in the predictions by comparison of measured data with the model results (e.g., Rutqvist et al, 2005aRutqvist et al, , 2005b.…”

Section: Introductionmentioning

confidence: 99%

DECOVALEX-THMC Task D: Long-Term Permeability/Porosity Changes inthe EDZ and Near Field due to THM and THC Processes in Volcanic andCrystaline-Bentonite Systems, Status Report October 2005

Birkhölzer¹,

Rutqvist²,

Sonnenthal³

et al. 2005

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SummaryThe DECOVALEX project is an international cooperative project initiated by SKI, the Swedish Nuclear Power Inspectorate, with participation of about 10 international organizations. The name DECOVALEX stands for DEvelopment of COupled models and their VALidation against Experiments. The general goal of this project is to encourage multidisciplinary interactive and cooperative research on modeling coupled processes in geologic formations in support of the performance assessment for underground storage of radioactive waste.Three multi-year project stages of DECOVALEX have been completed in the past decade, mainly focusing on coupled thermal-hydrological-mechanical processes. Currently, a fourth three-year project stage of DECOVALEX is under way, referred to as DECOVALEX-THMC. THMC stands for Thermal, Hydrological, Mechanical, and Chemical processes. The new project stage aims at expanding the traditional geomechanical scope of the previous DECOVALEX project stages by incorporating geochemical processes important for repository performance. The U.S. Department of Energy (DOE) leads Task D of the new DECOVALEX phase, entitled "Long-term Permeability/Porosity Changes in the EDZ and Near Field due to THC and THM Processes for Volcanic and Crystalline-Bentonite Systems." In its leadership role for Task D, DOE coordinates and sets the direction for the cooperative research activities of the international research teams engaged in Task D.The research program developed for Task D of DECOVALEX-THMC involves geomechanical and geochemical research areas. THM and THC processes may lead to changes in hydrological properties that are important for performance because the flow processes in the vicinity of emplacement tunnels will be altered from their initial state. Some of these changes can be permanent (irreversible), in which case they persist after the thermal conditions have returned to ambient; i.e., they will affect the entire regulatory compliance period. Geochemical processes also affect the water and gas chemistry close to the waste packages, which are relevant for waste package corrosion, buffer stability, and radionuclide transport.Research teams participating in Task D evaluate long-term THM and THC processes in two generic geologic repositories for radioactive waste, with the ultimate goal of determining the impact of geomechanical and geochemical processes on hydrologic properties and flow patterns. The two repositories are simplified representations of possible repository sites and emplacement conditions considered by the participating countries. One repository is a simplified model of the Yucca Mountain site, featuring a deep unsaturated volcanic rock formation with emplacement in open gas-filled tunnels. The second repository is located in saturated crystalline rock; emplacement tunnels are backfilled with a bentonite buffer material.During the past year, four international research teams from China, Germany, Japan, and USA have started research activities for the geomechanical and geochemical scenarios of...

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Section: Introductionmentioning

confidence: 99%

DECOVALEX-THMC Task D: Long-Term Permeability/Porosity Changes inthe EDZ and Near Field due to THM and THC Processes in Volcanic andCrystaline-Bentonite Systems, Status Report October 2005

Birkhölzer¹,

Rutqvist²,

Sonnenthal³

et al. 2005

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“…In addition, a three-dimensional, thermal-hydrologic model has been developed to represent thermal-hydrologic behavior for the (DST) at Yucca Mountain. Descriptions of the test, including analyses of the experimental data, are provided by Birkholzer and Tsang (2000), Rutqvist et al (2005), and Mukhopadhyay et al (2007). In the thermal-hydrologic models, the fractured rock is represented as a dual-permeability system (Buscheck et al 2002).…”

Section: The Thermal-hydrologic Modelmentioning

confidence: 99%

“…The DST was designed to investigate in situ thermal-hydrologic processes at the scale of a single emplacement drift (Birkholzer and Tsang 2000;Rutqvist et al 2005;Mukhopadhyay et al 2007). Figure 3 shows the plan view of the physical system.…”

Section: Study Domains and Gridsmentioning

confidence: 99%

Modeling Thermal-Hydrologic Processes for a Heated Fractured Rock System: Impact of a Capillary-Pressure Maximum

et al. 2009

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Various thermal-hydrologic models have been developed to simulate thermalhydrologic conditions in emplacement drifts and surrounding host rock for the proposed high-level nuclear waste repository at Yucca Mountain, Nevada. The modeling involves two-phase (liquid and gas) and two-component (water and air) transport in a fractured-rock system, which is conceptualized as a dual-permeability medium. Simulated hydrologic processes depend upon calibrated system parameters, such as the van Genuchten α and m, which quantify the capillary properties of the fractures and rock matrix. Typically, these parameters are not calibrated for strongly heat-driven conditions, i.e., conditions for which boiling and rock dryout occur. The objective of this study is to modify the relationship between capillary pressure and saturation, P c (S), for strongly heated conditions that drive saturation below the residual saturation (S → 0). We offer various extensions to the van Genuchten capillarypressure function and compare results from a thermal-hydrologic model with data collected during the Drift-Scale Test, an in situ thermal test at Yucca Mountain, to investigate the suitability of these various P c extension methods. The study suggests that the use of extension methods and the imposition of a capillary-pressure cap (or maximum) improve the agreement between Drift-Scale Test data and model results for strongly heat-driven conditions. However, for thermal-hydrologic models of the Yucca Mountain nuclear waste repository, temperature and relative humidity are insensitive to the choice of extension method for the capillary-pressure function. Therefore, the choice of extension method applied to models of drift-scale thermal-hydrologic behavior at Yucca Mountain can be made on the basis of numerical performance.

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“…In a TOUGH-FLAC simulation, the codes are coupled through external modules: one that calculates changes in effective stress as a function of multiphase pore pressure and thermal expansion, and one that corrects porosity, permeability, and capillary pressure as a function of stress. TOUGH-FLAC has been extensively applied in the Yucca Mountain Project (YMP) for the prediction of the evolution of coupled THM processes and for modeling the Yucca Mountain Drift Scale Test (Rutqvist et al 2005). …”

Section: Tough-flac (Used By Doe Team)mentioning

confidence: 99%

Characterising and modelling the excavation damaged zone in crystalline rock in the context of radioactive waste disposal

et al. 2008

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This paper describes current knowledge about the nature of and potential for thermo-hydromechanical-chemical modelling of the Excavation Damaged Zone (EDZ) around the excavations for an underground radioactive waste repository. In the first part of the paper, the disturbances associated with excavation are explained, together with reviews of Workshops that have been held on the subject. In the second part of the paper, the results of a DECOVALEX 1 research programme on modelling the EDZ are presented. Four research teams used four different models to simulate the complete stress-strain curve for Avro granite from the Swedish Äspö Hard Rock Laboratory. Subsequent research extended the work to computer simulation of the evolution of the repository using a 'wall block model' and a 'near-field model'. This included assessing the evolution of stress, failure and permeability and time dependent effects during repository evolution. As discussed, all the computer models are well suited to sensitivity studies for evaluating the influence of their respective supporting parameters on the complete stress-strain curve for rock and for modelling the EDZ.

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Coupled thermal–hydrological–mechanical analyses of the Yucca Mountain Drift Scale Test—Comparison of field measurements to predictions of four different numerical models

Cited by 99 publications

References 13 publications

DECOVALEX-THMC Task D: Long-Term Permeability/Porosity Changes inthe EDZ and Near Field due to THM and THC Processes in Volcanic andCrystaline-Bentonite Systems, Status Report October 2005

DECOVALEX-THMC Task D: Long-Term Permeability/Porosity Changes inthe EDZ and Near Field due to THM and THC Processes in Volcanic andCrystaline-Bentonite Systems, Status Report October 2005

Modeling Thermal-Hydrologic Processes for a Heated Fractured Rock System: Impact of a Capillary-Pressure Maximum

Characterising and modelling the excavation damaged zone in crystalline rock in the context of radioactive waste disposal

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