A comparative simulation study of coupled THM processes and their effect on fractured rock permeability around nuclear waste repositories

Rutqvist, Jonny; Barr, D.; Birkhölzer, Jens; Fujisaki, Kiyoshi; Kolditz, Olaf; Liu, Quansheng; Fujita, Tomoo; Wang, Wenqing; Zhang, Chengyuan

doi:10.1007/s00254-008-1552-1

Cited by 55 publications

(36 citation statements)

References 26 publications

(29 reference statements)

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“…Indeed, ROCMAS is a finite element code for fully coupled THM analysis under single phase, unsaturated flow conditions, whereas TOUGH-FLAC is based on the sequential coupling of a finite volume fluid flow code to a finite difference geomechanical code, but with full multiphase flow capability-see Wang et al, (2010), for a recent discussion on single-versus-multiphase fluid flow modeling approaches for this type of problem). The results in Figure 4.4.7-2 are also in general agreement with simulation results of other numerical models for the same DECOVALEX bench-mark test presented in Rutqvist et al (2008bRutqvist et al ( , 2009d. .4.7-2d is of utmost interest here because it shows the evolution of stress as a result of three sources: (1) swelling stress caused by saturation changes, (2) poro-elastic stress from fluid pressure changes under saturated conditions, and (3) thermal stress.…”

Section: Tough-flac Simulation Of a Bentonite-backfilled Nuclear Wastsupporting

confidence: 78%

Disposal systems evaluations and tool development : Engineered Barrier System (EBS) evaluation.

Rutqvist¹,

Liu²,

Steefel³

et al. 2011

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Eric Sonnenthal (LBNL) Engineered Barrier System (EBS) Evaluation This page is intentionally left blank Engineered Barrier System (EBS) Evaluation 5 Executive SummaryKey components of the nuclear fuel cycle are short-term storage and long-term disposal of nuclear waste. The latter encompasses the immobilization of used nuclear fuel (UNF) and radioactive waste streams generated by various phases of the nuclear fuel cycle, and the safe and permanent disposition of these waste forms in geological repository environments. The engineered barrier system (EBS) plays a very important role in the long-term isolation of nuclear waste in geological repository environments. EBS concepts and their interactions with the natural barrier are inherently important to the long-term performance assessment of the safety case where nuclear waste disposition needs to be evaluated for time periods of up to one million years. Making the safety case needed in the decision-making process for the recommendation and the eventual embracement of a disposal system concept requires a multi-faceted integration of knowledge and evidence-gathering to demonstrate the required confidence level in a deep geological disposal site and to evaluate longterm repository performance.The focus of this report is the following:• Evaluation of EBS in long-term disposal systems in deep geologic environments with emphasis on the multi-barrier concept;• Evaluation of key parameters in the characterization of EBS performance;• Identification of key knowledge gaps and uncertainties;• Evaluation of tools and modeling approaches for EBS processes and performance.The above topics will be evaluated through the analysis of the following:• Overview of EBS concepts for various NW disposal systems;• Natural and man-made analogs, room chemistry, hydrochemistry of deep subsurface environments, and EBS material stability in near-field environments;• Reactive Transport and Coupled Thermal-Hydrological-Mechanical-Chemical (THMC) processes in EBS;• Thermal analysis toolkit, metallic barrier degradation mode survey, and development of a Disposal Systems Evaluation Framework (DSEF).This report will focus on the multi-barrier concept of EBS and variants of this type which in essence is the most adopted concept by various repository programs. Empasis is given mainly to the evaluation of EBS materials and processes through the analysis of published studies in the scientific literature of past and existing repository research programs. Tool evaluations are also emphasized, particularly on THCM processes and chemical equilibria. Although being an increasingly important aspect of NW disposition, short-term or interim storage of NW will be briefly discussed but not to the extent of the EBS issues relevant to disposal systems in deep geologic environments. Interim storage will be discussed in the report Evaluation of Storage Concepts FY10 Final Report (Weiner et al. 2010). Engineered Barrier System (EBS) Evaluation 6This page is intentionally left blank Engineered Barrier System (EBS) Eva...

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Section: Tough-flac Simulation Of a Bentonite-backfilled Nuclear Wastsupporting

confidence: 78%

Disposal systems evaluations and tool development : Engineered Barrier System (EBS) evaluation.

Rutqvist¹,

Liu²,

Steefel³

et al. 2011

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“…change in swelling pressure due to porewater chemistry changes) couplings. Coupled THM models have been developed in Rutqvist et al (2009Rutqvist et al ( , 2011Rutqvist et al ( , 2014aRutqvist et al ( , 2014b. The results from the model developed in Rutqvist et al (2014b) show that it takes about 2780 years to fully saturate the EBS bentonite if the interaction between micro-and macrostructures is considered.…”

Section: Relevant Processesmentioning

confidence: 99%

Generic Argillite/Shale Disposal Reference Case

Zheng¹,

Colon²,

Bianchi³

et al. 2014

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“…3). The large-scale analysis included complete THM analysis of rock and bentonite buffer, to calculate the evolution of temperature, fluid pressure, bentonite saturation and swelling, and thermal stresses (see Rutqvist et al 2008b). …”

Section: Model Setupmentioning

confidence: 99%

A multiple-code simulation study of the long-term EDZ evolution of geological nuclear waste repositories

Rutqvist

Bäckström

Chijimatsu³

et al. 2008

Environ Geol

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This simulation study shows how widely different model approaches can be adapted to model the evolution of the excavation disturbed zone (EDZ) around a heated nuclear waste emplacement drift in fractured rock. The study includes modeling of coupled thermal-hydrological-mechanical (THM) processes, with simplified consideration of chemical coupling in terms of time-dependent strength degradation or subcritical crack growth. The different model approaches applied in this study include boundary element, finite element, finite difference, particle mechanics, and elastoplastic cellular automata methods. The simulation results indicate that thermally induced differential stresses near the top of the emplacement drift may cause progressive failure and permeability changes during the first 100 years (i.e., after emplacement and drift closure).Moreover, the results indicate that time-dependent mechanical changes may play only a small role during the first 100 years of increasing temperature and thermal stress, whereas such timedependency is insignificant after peak temperature, because decreasing thermal stress.

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A comparative simulation study of coupled THM processes and their effect on fractured rock permeability around nuclear waste repositories

Cited by 55 publications

References 26 publications

Disposal systems evaluations and tool development : Engineered Barrier System (EBS) evaluation.

Disposal systems evaluations and tool development : Engineered Barrier System (EBS) evaluation.

Generic Argillite/Shale Disposal Reference Case

A multiple-code simulation study of the long-term EDZ evolution of geological nuclear waste repositories

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