The disturbed rock zone at the Waste Isolation Pilot Plant.

Hansen, Francis D.

doi:10.2172/918258

Cited by 10 publications

(12 citation statements)

References 13 publications

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“…These calculations of the evolution (i.e., growth and healing) of the DRZ replicate observations made in the WIPP underground. The predicted size and shape of the DRZ around an opening based on a stress-invariant criterion (Figure 4) are similar to the size and shape derived from sonic velocity studies and from microscopy of core damage (Hansen 2003). The model output does not provide permeability directly, but the trend and magnitude of permeability around salt openings are understood in considerable detail.…”

Section: Full-scale Damage Healing In Saltsupporting

confidence: 55%

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Salt disposal of heat-generating nuclear waste.

Hansen²

2011

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This report summarizes the state of salt repository science, reviews many of the technical issues pertaining to disposal of heat-generating nuclear waste in salt, and proposes several avenues for future science-based activities to further the technical basis for disposal in salt. There are extensive salt formations in the forty-eight contiguous states, and many of them may be worthy of consideration for nuclear waste disposal. The United States has extensive experience in salt repository sciences, including an operating facility for disposal of transuranic wastes. The scientific background for salt disposal including laboratory and field tests at ambient and elevated temperature, principles of salt behavior, potential for fracture damage and its mitigation, seal systems, chemical conditions, advanced modeling capabilities and near-future developments, performance assessment processes, and international collaboration are all discussed. The discussion of salt disposal issues is brought current, including a summary of recent international workshops dedicated to high-level waste disposal in salt.Lessons learned from Sandia National Laboratories' experience on the Waste Isolation Pilot Plant and the Yucca Mountain Project as well as related salt experience with the Strategic Petroleum Reserve are applied in this assessment. Disposal of heat-generating nuclear waste in a suitable salt formation is attractive because the material is essentially impermeable, self-sealing, and thermally conductive. Conditions are chemically beneficial, and a significant experience base exists in understanding this environment. Within the period of institutional control, overburden pressure will seal fractures and provide a repository setting that limits radionuclide movement. A salt repository could potentially achieve total containment, with no releases to the environment in undisturbed scenarios for as long as the region is geologically stable. Much of the experience gained from United States repository development, such as seal system design, coupled process simulation, and application of performance assessment methodology, helps define a clear strategy for a heat-generating nuclear waste repository in salt.iv ACKNOWLEDGMENTS

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Section: Full-scale Damage Healing In Saltsupporting

confidence: 55%

“…Characterization of the DRZ has continued by means of laboratory testing, theoretical developments, modeling, and observations. Current understanding of the DRZ in salt indicates that the DRZ will be limited in extent over the regulatory period (Hansen 2003).…”

Section: Elements Of the Disturbed Rock Zone (Drz)mentioning

confidence: 99%

Salt disposal of heat-generating nuclear waste.

Hansen²

2011

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“…Salt repositories also need to be considered for potential HLW disposal given the isolating characteristics of the salt medium and its mechanical properties. SNL has a long history of research on salt repositories and in the development of models and tools to describe the thermomechanical behavior of salt Dawson, 1979, 1982;Hansen, 2003;Park et al, 2005;Stone et al, 2010). Recently, Stone et al (2010) utilized the SIERRA Mechanics code suite to model TM coupled processes in salt.…”

Section: Coupled Tm Processes In Saltmentioning

confidence: 99%

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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“…A repository rock that has the capacity to re-seal or heal fractures in the EDZ would be highly desirable for isolation purposes. The possibility of healing microfractures in salt under conditions at WIPP, for example, has been well established (Hansen 2003). Creation, evolution, healing and/or mitigation of the EDZ are of significant importance to seal system design and assessments of long-term safety.…”

Section: Excavation/construction Effectsmentioning

confidence: 99%

“…Hence, creep closure of underground openings in salt at ambient temperature is understood at a mechanistic level. By virtue of several studies at WIPP, the nature of the EDZ can be adequately described for engineering and analysis purposes in terms of stress invariants, which is conducive to finite element calculations (Hansen 2003). Long-term behavior including healing can be assessed by tracking the stress state within the structural calculation.…”

Section: Excavation/construction Effectsmentioning

confidence: 99%

Shale disposal of U.S. high-level radioactive waste.

Sassani¹,

Stone²,

Hansen³

et al. 2010

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This report evaluates the feasibility of high-level radioactive waste disposal in shale within the United States. The U.S. has many possible clay/shale/argillite basins with positive attributes for permanent disposal. Similar geologic formations have been extensively studied by international programs with largely positive results, over significant ranges of the most important material characteristics including permeability, rheology, and sorptive potential. This report is enabled by the advanced work of the international community to establish functional and operational requirements for disposal of a range of waste forms in shale media. We develop scoping performance analyses, based on the applicable features, events, and processes identified by international investigators, to support a generic conclusion regarding post-closure safety. Requisite assumptions for these analyses include waste characteristics, disposal concepts, and important properties of the geologic formation. We then apply lessons learned from Sandia experience on the Waste Isolation Pilot Project and the Yucca Mountain Project to develop a disposal strategy should a shale repository be considered as an alternative disposal pathway in the U.S.Disposal of high-level radioactive waste in suitable shale formations is attractive because the material is essentially impermeable and self-sealing, conditions are chemically reducing, and sorption tends to prevent radionuclide transport. Vertically and laterally extensive shale and clay formations exist in multiple locations in the contiguous 48 states. Thermal-hydrologicmechanical calculations indicate that temperatures near emplaced waste packages can be maintained below boiling and will decay to within a few degrees of the ambient temperature within a few decades (or longer depending on the waste form). Construction effects, ventilation, iv and the thermal pulse will lead to clay dehydration and deformation, confined to an excavation disturbed zone within a few meters of the repository, that can be reasonably characterized. Within a few centuries after waste emplacement, overburden pressures will seal fractures, resaturate the dehydrated zones, and provide a repository setting that strongly limits radionuclide movement to diffusive transport. Coupled hydrogeochemical transport calculations indicate maximum extents of radionuclide transport on the order of tens to hundreds of meters, or less, in a million years. Under the conditions modeled, a shale repository could achieve total containment, with no releases to the environment in undisturbed scenarios. The performance analyses described here are based on the assumption that long-term standards for disposal in clay/shale would be identical in the key aspects, to those prescribed for existing repository programs such as Yucca Mountain.This generic repository evaluation for shale is the first developed in the United States. Previous repository considerations have emphasized salt formations and volcanic rock formations. Much of the experience gaine...

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The disturbed rock zone at the Waste Isolation Pilot Plant.

Cited by 10 publications

References 13 publications

Salt disposal of heat-generating nuclear waste.

Salt disposal of heat-generating nuclear waste.

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

Shale disposal of U.S. high-level radioactive waste.

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