Multiscale Thermohydrologic Model Analyses Of Heterogeneity And Thermal Loading Factors For The Proposed Repository At Yucca Mountain

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Multiscale Thermohydrologic Model Analyses of Heterogeneity and Thermal-Loading Factors for the Proposed Repository at Yucca Mountain

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ISBN 13 :
Total Pages : 7 pages
Book Rating : 4.:/5 (684 download)

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Book Synopsis Multiscale Thermohydrologic Model Analyses of Heterogeneity and Thermal-Loading Factors for the Proposed Repository at Yucca Mountain by :

Download or read book Multiscale Thermohydrologic Model Analyses of Heterogeneity and Thermal-Loading Factors for the Proposed Repository at Yucca Mountain written by and published by . This book was released on 2002 with total page 7 pages. Available in PDF, EPUB and Kindle. Book excerpt: The MultiScale ThermoHydrologic Model (MSTHM) predicts thermohydrologic (TH) conditions in emplacement drifts and the adjoining host rock throughout the proposed nuclear-waste repository at Yucca Mountain. The MSTHM is a computationally efficient approach that accounts for TH processes occurring at a scale of a few tens of centimeters around individual waste packages and emplacement drifts, and for heat flow at the multi-kilometer scale at Yucca Mountain. The modeling effort presented here is an early investigation of the repository and is simulated at a lower temperature mode and with a different panel loading than the repository currently being considered for license application. We present these recent lower temperature mode MSTHM simulations that address the influence of repository-scale thermal-conductivity heterogeneity and the influence of preclosure operational factors affecting thermal-loading conditions. We can now accommodate a complex repository layout with emplacement drifts lying in non-parallel planes using a superposition process that combines results from multiple mountain-scale submodels. This development, along with other improvements to the MSTHM, enables more rigorous analyses of preclosure operational factors. These improvements include the ability to (1) predict TH conditions on a drift-by-drift basis, (2) represent sequential emplacement of waste packages along the drifts, and (3) incorporate distance- and time-dependent heat-removal efficiency associated with drift ventilation. Alternative approaches to addressing repository-scale thermal-conductivity heterogeneity are investigated. We find that only one of the four MSTHM submodel types needs to incorporate thermal-conductivity heterogeneity. For a particular repository design, we find that the most influential parameters are (1) percolation-flux distribution, (2) thermal-conductivity heterogeneity within the host-rock units, (3) the sequencing of waste-package emplacement, and (4) the duration of the preclosure ventilation period.

Multiscale Thermohydrologic Model Analyses of Heterogeneity and Thermal-Loading Factors for a Proposed Nuclear Waste Repository

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ISBN 13 :
Total Pages : 38 pages
Book Rating : 4.:/5 (873 download)

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Book Synopsis Multiscale Thermohydrologic Model Analyses of Heterogeneity and Thermal-Loading Factors for a Proposed Nuclear Waste Repository by :

Download or read book Multiscale Thermohydrologic Model Analyses of Heterogeneity and Thermal-Loading Factors for a Proposed Nuclear Waste Repository written by and published by . This book was released on 2004 with total page 38 pages. Available in PDF, EPUB and Kindle. Book excerpt: The MultiScale ThermoHydrologic Model is used to predict thermal-hydrologic conditions in emplacement drifts and the adjoining host-rock throughout a proposed nuclear waste repository. The presented modeling effort simulates a lower temperature operation mode with a different panel loading than the repository currently being considered for the Yucca Mountain license application. Simulations address the influence of repository-scale thermal-conductivity heterogeneity and the influence of pre-closure operational factors on thermal-loading conditions. MSTHM can accommodate a complex repository layout, a development that, along with other improvements, enables more rigorous analyses of preclosure operational factors. Differences in MSTHM output occurring with these new capabilities are noted for a new sequential waste-package loading technique compared to a standard simultaneous loading technique. Alternative approaches to modeling repository-scale thermal-conductivity heterogeneity in the host-rock units are investigated, and study incorporating geostatistically-varied host-rock thermal conductivity is discussed.

Multiscale Thermohydrologic Model Supporting the Licence Application for the Yucca Mountain Repository

Author : Y. Sun
Publisher :
ISBN 13 :
Total Pages : pages
Book Rating : 4.:/5 (316 download)

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Book Synopsis Multiscale Thermohydrologic Model Supporting the Licence Application for the Yucca Mountain Repository by : Y. Sun

Download or read book Multiscale Thermohydrologic Model Supporting the Licence Application for the Yucca Mountain Repository written by Y. Sun and published by . This book was released on 2006 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt: The MultiScale ThermoHydrologic Model (MSTHM) predicts thermal-hydrologic (TH) conditions within emplacement tunnels (drifts) and in the adjoining host rock at Yucca Mountain, Nevada, which is the proposed site for a radioactive waste repository in the US. Because these predictions are used in the performance assessment of the Yucca Mountain repository, they must address the influence of variability and uncertainty of the engineered- and natural-system parameters that significantly influence those predictions. Parameter-sensitivity studies show that the MSTHM predictions adequately propagate the influence of parametric variability and uncertainty. Model-validation studies show that the influence of conceptual-model uncertainty on the MSTHM predictions is insignificant compared to that of parametric uncertainty, which is propagated through the MSTHM.

The Multi-Scale Model Approach to Thermohydrology at Yucca Mountain

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ISBN 13 :
Total Pages : 23 pages
Book Rating : 4.:/5 (682 download)

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Book Synopsis The Multi-Scale Model Approach to Thermohydrology at Yucca Mountain by :

Download or read book The Multi-Scale Model Approach to Thermohydrology at Yucca Mountain written by and published by . This book was released on 2002 with total page 23 pages. Available in PDF, EPUB and Kindle. Book excerpt: The Multi-Scale Thermo-Hydrologic (MSTH) process model is a modeling abstraction of them1 hydrology (TH) of the potential Yucca Mountain repository at multiple spatial scales. The MSTH model as described herein was used for the Supplemental Science and Performance Analyses (BSC, 2001) and is documented in detail in CRWMS M & O (2000) and Glascoe et al. (2002). The model has been validated to a nested grid model in Buscheck et al. (In Review). The MSTH approach is necessary for modeling thermal hydrology at Yucca Mountain for two reasons: (1) varying levels of detail are necessary at different spatial scales to capture important TH processes and (2) a fully-coupled TH model of the repository which includes the necessary spatial detail is computationally prohibitive. The MSTH model consists of six ''submodels'' which are combined in a manner to reduce the complexity of modeling where appropriate. The coupling of these models allows for appropriate consideration of mountain-scale thermal hydrology along with the thermal hydrology of drift-scale discrete waste packages of varying heat load. Two stages are involved in the MSTH approach, first, the execution of submodels, and second, the assembly of submodels using the Multi-scale Thermohydrology Abstraction Code (MSTHAC). MSTHAC assembles the submodels in a five-step process culminating in the TH model output of discrete waste packages including a mountain-scale influence.

Multiscale Thermohydrologic Model

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ISBN 13 :
Total Pages : pages
Book Rating : 4.:/5 (682 download)

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Book Synopsis Multiscale Thermohydrologic Model by :

Download or read book Multiscale Thermohydrologic Model written by and published by . This book was released on 2000 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt: Performance assessment and design evaluation require a modeling tool that simultaneously accounts for processes occurring at a scale of a few tens of centimeters around individual waste packages and emplacement drifts, and also on behavior at the scale of the mountain. Many processes and features must be considered, including non-isothermal, multiphase-flow in rock of variable saturation and thermal radiation in open cavities. Also, given the nature of the fractured rock at Yucca Mountain, a dual-permeability approach is needed to represent permeability. A monolithic numerical model with all these features requires too large a computational cost to be an effective simulation tool, one that is used to examine sensitivity to key model assumptions and parameters. We have developed a multi-scale modeling approach that effectively simulates 3D discrete-heat-source, mountain-scale thermohydrologic behavior at Yucca Mountain and captures the natural variability of the site consistent with what we know from site characterization and waste-package-to-waste-package variability in heat output. We describe this approach and present results examining the role of infiltration flux, the most important natural-system parameter with respect to how thermohydrologic behavior influences the performance of the repository.

Multiscale Thermohydrologic Model

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ISBN 13 :
Total Pages : 606 pages
Book Rating : 4.:/5 (16 download)

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Book Synopsis Multiscale Thermohydrologic Model by :

Download or read book Multiscale Thermohydrologic Model written by and published by . This book was released on 2004 with total page 606 pages. Available in PDF, EPUB and Kindle. Book excerpt: The purpose of the multiscale thermohydrologic model (MSTHM) is to predict the possible range of thermal-hydrologic conditions, resulting from uncertainty and variability, in the repository emplacement drifts, including the invert, and in the adjoining host rock for the repository at Yucca Mountain. Thus, the goal is to predict the range of possible thermal-hydrologic conditions across the repository; this is quite different from predicting a single expected thermal-hydrologic response. The MSTHM calculates the following thermal-hydrologic parameters: temperature, relative humidity, liquid-phase saturation, evaporation rate, air-mass fraction, gas-phase pressure, capillary pressure, and liquid- and gas-phase fluxes (Table 1-1). These thermal-hydrologic parameters are required to support ''Total System Performance Assessment (TSPA) Model/Analysis for the License Application'' (BSC 2004 [DIRS 168504]). The thermal-hydrologic parameters are determined as a function of position along each of the emplacement drifts and as a function of waste package type. These parameters are determined at various reference locations within the emplacement drifts, including the waste package and drip-shield surfaces and in the invert. The parameters are also determined at various defined locations in the adjoining host rock. The MSTHM uses data obtained from the data tracking numbers (DTNs) listed in Table 4.1-1. The majority of those DTNs were generated from the following analyses and model reports: (1) ''UZ Flow Model and Submodels'' (BSC 2004 [DIRS 169861]); (2) ''Development of Numerical Grids for UZ Flow and Transport Modeling'' (BSC 2004); (3) ''Calibrated Properties Model'' (BSC 2004 [DIRS 169857]); (4) ''Thermal Conductivity of the Potential Repository Horizon'' (BSC 2004 [DIRS 169854]); (5) ''Thermal Conductivity of the Non-Repository Lithostratigraphic Layers'' (BSC 2004 [DIRS 170033]); (6) ''Ventilation Model and Analysis Report'' (BSC 2004 [DIRS 169862]); (7) ''Heat Capacity Analysis Report'' (BSC 2004 [DIRS 170003]).

Validating Thermohydrologic Models Using the Drift Scale Test of the Proposed Repository at Yucca Mountain

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ISBN 13 :
Total Pages : 1 pages
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Book Synopsis Validating Thermohydrologic Models Using the Drift Scale Test of the Proposed Repository at Yucca Mountain by :

Download or read book Validating Thermohydrologic Models Using the Drift Scale Test of the Proposed Repository at Yucca Mountain written by and published by . This book was released on 2007 with total page 1 pages. Available in PDF, EPUB and Kindle. Book excerpt:

The Influence of Proposed Repository Thermal Load on MultiphaseFlow and Heat Transfer in the Unsaturated Zone of Yucca Mountain

Author : G. S. Bodvarsson
Publisher :
ISBN 13 :
Total Pages : pages
Book Rating : 4.:/5 (316 download)

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Book Synopsis The Influence of Proposed Repository Thermal Load on MultiphaseFlow and Heat Transfer in the Unsaturated Zone of Yucca Mountain by : G. S. Bodvarsson

Download or read book The Influence of Proposed Repository Thermal Load on MultiphaseFlow and Heat Transfer in the Unsaturated Zone of Yucca Mountain written by G. S. Bodvarsson and published by . This book was released on 2006 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt: This paper investigates the impact of proposed repositorythermal-loading on mountain-scale flow and heat transfer in theunsaturated fractured rock of Yucca Mountain, Nevada. In this context, amodel has been developed to study the coupled thermal-hydrological (TH)processes at the scale of the entire Yucca Mountain. This mountain-scaleTH model implements the current geological framework and hydrogeologicalconceptual models, and incorporates the latest rock thermal andhydrological properties. The TH model consists of a two-dimensionalnorth-south vertical cross section across the entire unsaturated zonemodel domain and uses refined meshes near and around the proposedrepository block, based on the current repository design, drift layout, thermal loading scenario, and estimated current and future climaticconditions. The model simulations provide insights into thermallyaffected liquid saturation, gas- and liquid-phase fluxes, and elevatedwater and rock temperature, which in turn allow modelers to predict thechanges in water flux driven by evaporation/condensation processes, anddrainage between drifts.

Index Medicus

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ISBN 13 :
Total Pages : 1616 pages
Book Rating : 4.:/5 (319 download)

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Book Synopsis Index Medicus by :

Download or read book Index Medicus written by and published by . This book was released on 2003 with total page 1616 pages. Available in PDF, EPUB and Kindle. Book excerpt: Vols. for 1963- include as pt. 2 of the Jan. issue: Medical subject headings.

Multiscale Thermohydrologic Model Sensitivity Analysis

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ISBN 13 :
Total Pages : 67 pages
Book Rating : 4.:/5 (684 download)

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Book Synopsis Multiscale Thermohydrologic Model Sensitivity Analysis by :

Download or read book Multiscale Thermohydrologic Model Sensitivity Analysis written by and published by . This book was released on 1998 with total page 67 pages. Available in PDF, EPUB and Kindle. Book excerpt: A multiscale, thermohydrologic (TH) modeling approach (or methodology) has been developed that integrates the results from one- dimensional (1-D), two-dimensional (2-D), and three-dimensional (3-D) drift-scale models and a 3-D mountain-scale model to calculate the near-field TH variables affecting the performance of the engineered barrier system (EBS) of the potential repository at Yucca Mountain. This information is required by Total System Performance Assessment- Viability Assessment (TSPA-VA) to assess waste-package (WP) corrosion, waste-form dissolution, and radionuclide transport in the EBS. This methodology is a computationally efficient, flexible means of determining EBS TH conditions; such determination would otherwise require millions of grid blocks if a brute-force numerical model were used. The methodology determines EBS TH conditions as a function of location within the repository and WP type.

THE INFLUENCE OF REPOSITORY THERMAL LOAD ON MULTIPHASE FLOW AND HEAT TRANSFER IN THE UNSATURATED ZONE OF YUCCA MOUNTAIN.

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ISBN 13 :
Total Pages : pages
Book Rating : 4.:/5 (727 download)

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Book Synopsis THE INFLUENCE OF REPOSITORY THERMAL LOAD ON MULTIPHASE FLOW AND HEAT TRANSFER IN THE UNSATURATED ZONE OF YUCCA MOUNTAIN. by :

Download or read book THE INFLUENCE OF REPOSITORY THERMAL LOAD ON MULTIPHASE FLOW AND HEAT TRANSFER IN THE UNSATURATED ZONE OF YUCCA MOUNTAIN. written by and published by . This book was released on 2006 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt: This paper investigates the impact of proposed repository thermal-loading on mountain-scale flow and heat transfer in the unsaturated fractured rock of Yucca Mountain, Nevada. In this context, a model has been developed to study the coupled thermal-hydrological (TH) processes at the scale of the entire Yucca Mountain. This mountain-scale TH model implements the current geological framework and hydrogeological conceptual models, and incorporates the latest rock thermal and hydrological properties. The TH model consists of a two-dimensional north-south vertical cross section across the entire unsaturated zone model domain and uses refined meshes near and around the proposed repository block, based on the current repository design, drift layout, thermal loading scenario, and estimated current and future climatic conditions. The model simulations provide insights into thermally affected liquid saturation, gas- and liquid-phase fluxes, and elevated water and rock temperature, which in turn allow modelers to predict the changes in water flux driven by evaporation/condensation processes, and drainage between drifts.

Thermally Driven Moisture Redistribution in Partially Saturated Porous Media

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ISBN 13 :
Total Pages : 200 pages
Book Rating : 4.:/5 (683 download)

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Book Synopsis Thermally Driven Moisture Redistribution in Partially Saturated Porous Media by :

Download or read book Thermally Driven Moisture Redistribution in Partially Saturated Porous Media written by and published by . This book was released on 1995 with total page 200 pages. Available in PDF, EPUB and Kindle. Book excerpt: It is widely recognized that the decay heat produced by high-level radioactive waste (HLW) will likely have a significant impact on both the pre- and post-closure performance of the proposed repository at Yucca Mountain (YM), in southwest Nevada. The task of delineating which aspects of that impact are favorable to isolation performance and which are adverse is an extremely challenging technical undertaking because of such factors as the hydrothermal regimes involved, heterogeneity of the geologic media, and the time and space scales involved. This difficulty has motivated both the US Department of Energy (DOE) and the US Nuclear Regulatory Commission (NRC) to undertake multi-year thermohydrology research programs to examine the effects of decay heat on pre- and post-closure performance of the repository. Both of these organizations are currently pursuing laboratory and field experiments, as well as numerical modeling studies, to advance the state of knowledge of the thermohydrologic phenomena relevant to the proposed geologic repository. The NRC-sponsored Thermohydrology Research Project, which was initiated in mid-1989 at the Center for Nuclear Waste Regulatory Analyses (CNWRA), began with the intent of addressing a broad spectrum of generic thermohydrologic questions. While some of these questions were answered in the conduct of the study, other new and challenging ones were encountered. Subsequent to that report, laboratory-scale experiments were designed to address four fundamental questions regarding thermohydrologic phenomena: what are the principal mechanisms controlling the redistribution of moisture; under what hydrothermal conditions and time frames do individual mechanisms predominate; what driving mechanism is associated with a particular hydrothermal regime; what is the temporal and spatial scale of each hydrothermal regime? This report presents the research results and findings obtained since issuance of the first progress report. 85 refs.

Technical Work Plan for

Author : B. Kirstein
Publisher :
ISBN 13 :
Total Pages : pages
Book Rating : 4.:/5 (316 download)

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Book Synopsis Technical Work Plan for by : B. Kirstein

Download or read book Technical Work Plan for written by B. Kirstein and published by . This book was released on 2006 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt: The primary objective of Revision 04 of the MSTHM report is to provide TSPA with revised repository-wide MSTHM analyses that incorporate updated percolation flux distributions, revised hydrologic properties, updated IEDs, and information pertaining to the emplacement of transport, aging, and disposal (TAD) canisters. The updated design information is primarily related to the incorporation of TAD canisters, but also includes updates related to superseded IEDs describing emplacement drift cross-sectional geometry and layout. The intended use of the results of Revision 04 of the MSTHM report, as described in this TWP, is to predict the evolution of TH conditions (temperature, relative humidity, liquid-phase saturation, and liquid-phase flux) at specified locations within emplacement drifts and in the adjoining near-field host rock along all emplacement drifts throughout the repository. This information directly supports the TSPA for the nominal and seismic scenarios. The revised repository-wide analyses are required to incorporate updated parameters and design information and to extend those analyses out to 1,000,000 years. Note that the previous MSTHM analyses reported in Revision 03 of Multiscale Thermohydrologic Model (BSC 2005 [DIRS 173944]) only extend out to 20,000 years. The updated parameters are the percolation flux distributions, including incorporation of post-10,000-year distributions, and updated calibrated hydrologic property values for the host-rock units. The applied calibrated hydrologic properties will be an updated version of those available in Calibrated Properties Model (BSC 2004 [DIRS 169857]). These updated properties will be documented in an Appendix of Revision 03 of UZ Flow Models and Submodels (BSC 2004 [DIRS 169861]). The updated calibrated properties are applied because they represent the latest available information. The reasonableness of applying the updated calibrated' properties to the prediction of near-fieldin-drift TH conditions will be evaluated and justified. Some of this evaluation will be conducted in conjunction with the post-model development validation activity involving comparisons of predicted TH conditions with measured TH conditions in the DST. The expected result is that, consistent with what was found in Revision 03 of Multiscale Thermohydrologic Model (BSC 2005 [DIRS 173944], Section 6.3.9), near-field/in-drift TH behavior is insensitive to a wide range of host-rock hydrologic property values. It is the intention of the work described in this TWP to propagate the new infiltration fluxes from the replacement infiltration model, by using the percolation fluxes from the revised site-scale unsaturated zone (UZ) flow model that has applied those new infiltration fluxes. The percolation flux distributions will be obtained from the updated site-scale UZ flow model, which has applied updated infiltration flux maps. Another objective of the work scope is to develop, implement, and validate a revised TH submodel-construction approach. This revised approach utilizes interpolation among a set of generic LDTH submodels that are run for a range of percolation flux histories that cover a sufficiently broad range of infiltration flux uncertainty, as well as for four host-rock units (two lithophysal units and two nonlithophysal units), and for three thermal property sets (low, mean, and high). A key motivation for this revised LDTH submodel-construction approach is to enable the MSTHM to be more flexible in addressing a broad range of infiltration flux cases. This approach allows the generic LDTH submodel simulations to be conducted prior to receiving percolation flux maps.

Near-field Thermal-hydrological Behavior for Alternative Repository Designs at Yucca Mountain

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ISBN 13 :
Total Pages : 11 pages
Book Rating : 4.:/5 (684 download)

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Book Synopsis Near-field Thermal-hydrological Behavior for Alternative Repository Designs at Yucca Mountain by :

Download or read book Near-field Thermal-hydrological Behavior for Alternative Repository Designs at Yucca Mountain written by and published by . This book was released on 1996 with total page 11 pages. Available in PDF, EPUB and Kindle. Book excerpt: Three-dimensional calculations that explicitly represent a realistic mixture of waste packages (WPs) are used to analyze decay-heat-driven thermal-hydrological behavior around emplacement drifts in a potential high-level waste facility at Yucca Mountain, Calculations, using the NUFT code, compare two fundamentally different ways that WPs can be arranged in the repository, with a focus on temperature, relative humidity, and liquid-phase flux on WPs. These quantities strongly affect WP integrity and the mobilization and release of radionuclides from WPs. Point-load spacing, which places the WPs roughly equidistant from each other, thermally isolates WPs from each other, causing large variability in temperature, relative humidity, and liquid-phase flux among the drifts. Line-load spacing, which WPs nearly end to end in widely spaced drifts, results in more locally intensive and uniform heating along the drifts, causing hotter, drier and more uniform conditions. A larger and more persistent reduction in relative humidity on WPs occurs if the drifts are backfilled with a low thermal conductivity granular material with hydrologic properties that minimize moisture wicking.

Localized Dryout

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ISBN 13 :
Total Pages : 8 pages
Book Rating : 4.:/5 (683 download)

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Download or read book Localized Dryout written by and published by . This book was released on 1995 with total page 8 pages. Available in PDF, EPUB and Kindle. Book excerpt: For a nuclear waste repository in the unsaturated zone at Yucca Mountain, there are two thermal loading approaches to using decay heat constructively -- that is, to substantially reduce relative humidity and liquid flow near waste packages for a considerable time, and thereby limit waste package degradation and radionuclide dissolution and release. ''Extended dryout'' achieves these effects with a thermal load high enough to generate large-scale (coalesced) rock dryout. ''Localized dryout''(which uses wide drift spacing and a thermal load too low for coalesced dryout) achieves them by maintaining a large temperature difference between the waste package and drift wall; this is done with close waste package spacing (generating a high line-heat load) and/or low-thermal-conductivity backfill in the drift. Backfill can greatly reduce relative humidity on the waste package in both the localized and extended dryout approaches. Besides using decay heat constructively, localized dryout reduces the possibility that far-field temperature rise and condensate buildup above the drifts might adversely affect waste isolation.

Influence of Hydrologic Heterogencity on Thermal-Hydrologic Behavior in Emplacement Drifts

Author : Y. Sun
Publisher :
ISBN 13 :
Total Pages : pages
Book Rating : 4.:/5 (316 download)

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Book Synopsis Influence of Hydrologic Heterogencity on Thermal-Hydrologic Behavior in Emplacement Drifts by : Y. Sun

Download or read book Influence of Hydrologic Heterogencity on Thermal-Hydrologic Behavior in Emplacement Drifts written by Y. Sun and published by . This book was released on 2006 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt: Fracture networks have been characterized as highly permeable continuum within the porous rock matrix in thermal-hydrologic models used to support performance assessments of the proposed nuclear-waste repository at Yucca Mountain. Uncertainty and spatial variability of the fracture permeability are important considerations for understanding thermal-hydrologic behavior within the host rock surrounding an emplacement drift. In this paper, we conducted numerical experiments with a number of realizations of intrinsic fracture permeability and examine thermal conditions around an emplacement drift. Peak temperature and boiling duration on the drift wall are used as indices to quantify, the influence of fracture permeability. The variability of peak temperature and boiling duration resulting from small-scale fracture-permeability heterogeneity is compared with the variability resulting from variability of host-rock thermal conductivity and infiltration flux. An examination of rock dryout and condensate drainage shows that small-scale heterogeneity in fracture permeability results in a relatively small range in dryout volume and does not prevent the shedding of condensate through the pillar-separating emplacement drifts.

Evaluation of Thermo-hydrological Performance in Support of the Thermal Loading Systems Study

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ISBN 13 :
Total Pages : 19 pages
Book Rating : 4.:/5 (727 download)

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Book Synopsis Evaluation of Thermo-hydrological Performance in Support of the Thermal Loading Systems Study by :

Download or read book Evaluation of Thermo-hydrological Performance in Support of the Thermal Loading Systems Study written by and published by . This book was released on 1994 with total page 19 pages. Available in PDF, EPUB and Kindle. Book excerpt: Heat generated as a result of emplacing spent nuclear fuel will significantly affect the pre- and post-closure performance of the Mined Geological Disposal System (MGDS) at the potential repository site in Yucca Mountain. Understanding thermo-hydrological behavior under repository thermal loads is essential in (a) planning and conducting the site characterization and testing program, (b) designing the repository and engineered barrier system, and (c) assessing performance. The greatest concern for hydrological performance is source of water that would contact a waste package, accelerate its failure rate, and eventually transport radionuclides to the water table. The primary sources of liquid water are: (1) natural infiltration, (2) condensate generated under boiling conditions, and (3) condensate generated under sub-boiling conditions. Buoyant vapor flow, occurring either on a sub-repository scale or on a mountain scale, any affect the generation of the second and third sources of liquid water. A system of connected fractures facilitates repository-heat-driven gas and liquid flow as well as natural infiltration. With the use of repository-scale and sub-repository-scale models, the authors analyze thermo-hydrological behavior for Areal Mass Loadings (AMLs) of 24.2, 35.9, 55.3, 83.4, and 110.5 MTU/acre for a wide range of bulk permeability. They examine the temporal and spatial extent of the temperature and saturation changes during the first 100,000 yr. They also examine the sensitivity of mountain scale moisture redistribution to a range of AMLs and bulk permeabilities. In addition, they investigate how boiling and buoyant, gas-phase convection influence thermo-hydrological behavior in the vicinity of emplacement drifts containing spent nuclear fuel.