EBookClubs

Read Books & Download eBooks Full Online

EBookClubs

Read Books & Download eBooks Full Online

Book Geostatistical and Stochastic Study of Flow and Transport in the Unsaturated Zone at Yucca Mountain

Download or read book Geostatistical and Stochastic Study of Flow and Transport in the Unsaturated Zone at Yucca Mountain written by and published by . This book was released on 2007 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt: Yucca Mountain has been proposed by the U.S. Department of Energy as the nation's long-term, permanent geologic repository for spent nuclear fuel or high-level radioactive waste. The potential repository would be located in Yucca Mountain's unsaturated zone (UZ), which acts as a critical natural barrier delaying arrival of radionuclides to the water table. Since radionuclide transport in groundwater can pose serious threats to human health and the environment, it is important to understand how much and how fast water and radionuclides travel through the UZ to groundwater. The UZ system consists of multiple hydrogeologic units whose hydraulic and geochemical properties exhibit systematic and random spatial variation, or heterogeneity, at multiple scales. Predictions of radionuclide transport under such complicated conditions are uncertain, and the uncertainty complicates decision making and risk analysis. This project aims at using geostatistical and stochastic methods to assess uncertainty of unsaturated flow and radionuclide transport in the UZ at Yucca Mountain. Focus of this study is parameter uncertainty of hydraulic and transport properties of the UZ. The parametric uncertainty arises since limited parameter measurements are unable to deterministically describe spatial variability of the parameters. In this project, matrix porosity, permeability and sorption coefficient of the reactive tracer (neptunium) of the UZ are treated as random variables. Corresponding propagation of parametric uncertainty is quantitatively measured using mean, variance, 5th and 95th percentiles of simulated state variables (e.g., saturation, capillary pressure, percolation flux, and travel time). These statistics are evaluated using a Monte Carlo method, in which a three-dimensional flow and transport model implemented using the TOUGH2 code is executed with multiple parameter realizations of the random model parameters. The project specifically studies uncertainty of unsaturated flow and radionuclide transport caused by multi-scale heterogeneity at the layer and local scales. Typically, in studies of Yucca Mountain, the layer scale refers to hydrogeologic layers with layer-wise average properties, and the local scale refers to the spatial variation of hydraulic properties within a layer. While most studies of radionuclide transport in the UZ have been conducted at the layer scale, the uncertainty at the local scale within a layer is also important, since it affects flow path, velocity, and travel time of radionuclide. This report first presents the uncertainty caused by layer-scale heterogeneity of matrix permeability, porosity, and sorption coefficients of reactive tracers. Homogeneous fields of the parameters are generated at each hydrogeologic layer for Monte Carlo simulations. This study is referred to as the homogeneous case. To assess the uncertainty caused by local-scale heterogeneity, the sequential Gaussian simulator (SGSIM) of GSLIB (Deutsch and Journel, 1998) is used to generate heterogeneous parameter fields within each layer, and Monte Carlo simulations are conducted. This study is referred to as the heterogeneous cases. For the homogeneous and heterogeneous cases, the mean, variance, 5th and 95th percentiles of simulated state variables are estimated for uncertainty assessment. In addition, the statistics of the two cases are compared to investigate effect of local-scale heterogeneity on the unsaturated flow and radionuclide transport. It is found that the local-scale heterogeneity increased the predictive uncertainty of percolation flux and cumulative mass arrival for computational blocks below the footprint of proposed repository, whereas mean predictions are hardly affected. The local-scale heterogeneity significantly affects travel times to the water table for both conservative and reactive tracers. In the early simulation period, tracer mean travel times are delayed, whereas the influence of local-scale heterogeneity diminishes during the late simulation period. Simulated state variables in this project are more realistic than those of using one- or two dimensional models, due to a three-dimensional numerical model used in the project to characterize hydrological conditions at the UZ. Therefore, we expect that results of this project can be used directly to facilitate DOE site performance analysis and decision making.

Book Yucca Mountain Site Characterization Project Bibliography 1994 1995

Download or read book Yucca Mountain Site Characterization Project Bibliography 1994 1995 written by and published by . This book was released on 1996 with total page 456 pages. Available in PDF, EPUB and Kindle. Book excerpt:

Book Yucca Mountain Site Characterization Project Bibliography 1992 1993

Download or read book Yucca Mountain Site Characterization Project Bibliography 1992 1993 written by and published by . This book was released on 1994 with total page 312 pages. Available in PDF, EPUB and Kindle. Book excerpt:

Book Selected Water Resources Abstracts

Download or read book Selected Water Resources Abstracts written by and published by . This book was released on 1990 with total page 1180 pages. Available in PDF, EPUB and Kindle. Book excerpt:

Book Proceedings of the Conference on Geostatistical Sensitivity and Uncertainty Methods for Ground water Flow and Radionuclide Transport Modeling San Francisco California September 15 17 1987

Download or read book Proceedings of the Conference on Geostatistical Sensitivity and Uncertainty Methods for Ground water Flow and Radionuclide Transport Modeling San Francisco California September 15 17 1987 written by Bruce E. Buxton and published by . This book was released on 1989 with total page 696 pages. Available in PDF, EPUB and Kindle. Book excerpt: Very Good,No Highlights or Markup,all pages are intact.

Book Radioactive Waste Management

Download or read book Radioactive Waste Management written by and published by . This book was released on 1995-04 with total page 544 pages. Available in PDF, EPUB and Kindle. Book excerpt:

Book Flow and transport in the unsaturated zone

Download or read book Flow and transport in the unsaturated zone written by C.P. Jackson and published by . This book was released on 1985 with total page 4 pages. Available in PDF, EPUB and Kindle. Book excerpt:

Book Water resources Investigations Report

Download or read book Water resources Investigations Report written by and published by . This book was released on 1997 with total page 296 pages. Available in PDF, EPUB and Kindle. Book excerpt:

Book Characterization of Hydrogeologic Units Using Matrix Properties Yucca Mountain Nevada

Download or read book Characterization of Hydrogeologic Units Using Matrix Properties Yucca Mountain Nevada written by and published by DIANE Publishing. This book was released on 2001 with total page 69 pages. Available in PDF, EPUB and Kindle. Book excerpt: Determination of the suitability of Yucca Mountain, in southern Nevada, as a geologic repository for high-level radioactive waste requires the use of numerical flow and transport models. Input for these models includes parameters that describe hydrologic properties and the initial and boundary conditions for all rock materials within the unsaturated zone, as well as some of the upper rocks in the saturated zone. There are 30 hydrogeologic units in the unsaturated zone, and each unit is defined by limited ranges where a discrete volume of rock contains similar hydrogeologic properties. These hydrogeologic units can be easily located in space by using three-dimensional lithostratigraphic models based on relationships of the properties with the lithostratigraphy. Physical properties of bulk density, porosity, and particle density; flow properties of saturated hydraulic conductivity and moisture-retention characteristics; and the state variables (variables describing the current state of field conditions) of saturation and water potential were determined for each unit. Units were defined using (1) a data base developed from 4,892 rock samples collected from the coring of 23 shallow and 8 deep boreholes, (2) described lithostratigraphic boundaries and corresponding relations to porosity, (3) recognition of transition zones with pronounced changes in properties over short vertical distances, (4) characterization of the influence of mineral alteration on hydrologic properties such as permeability and moisture-retention characteristics, and (5) a statistical analysis to evaluate where boundaries should be adjusted to minimize the variance within layers. This study describes the correlation of hydrologic properties to porosity, a property that is well related to the lithostratigraphy and depositional and cooling history of the volcanic deposits and can, therefore, be modeled to be distributed laterally.

Book DRIFT SCALE MODELING

Download or read book DRIFT SCALE MODELING written by and published by . This book was released on 1996 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt: Unsaturated flow in heterogeneous fractured porous rock was simulated using a stochastic continuum model (SCM). In this model, both the more conductive fractures and the less permeable matrix are generated within the framework of a single continuum stochastic approach, based on non-parametric indicator statistics. High-permeable fracture zones are distinguished from low-permeable matrix zones in that they have assigned a long range correlation structure in prescribed directions. The SCM was applied to study small-scale flow in the vicinity of an access tunnel, which is currently being drilled in the unsaturated fractured tuff formations at Yucca Mountain, Nevada. Extensive underground testing is underway in this tunnel to investigate the suitability of Yucca Mountain as an underground nuclear waste repository. Different flow scenarios were studied in the present paper, considering the flow conditions before and after the tunnel emplacement, and assuming steady-state net infiltration as well as episodic pulse infiltration. Although the capability of the stochastic continuum model has not yet been fully explored, it has been demonstrated that the SCM is a good alternative model feasible of describing heterogeneous flow processes in unsaturated fractured tuff at Yucca Mountain.

Book Theory Modeling and Field Investigation in Hydrogeology

Download or read book Theory Modeling and Field Investigation in Hydrogeology written by S. P. Neuman and published by Geological Society of America. This book was released on 2000-01-01 with total page 260 pages. Available in PDF, EPUB and Kindle. Book excerpt: The refereed and edited proceedings of the symposium Schlomo P. Neuman: Recent Advances After 30 Years of Exceptional Contributions to Well Hydraulics, Numerical Modeling, and Field Investigations, which was held in Tucson, Arizona, in October 1998. Among the topics are four decades of inverse problems in hydrogeology, a connected-network paradigm for the alluvial aquifer system, the influence of multi-scale structure in non-ergodic solute transport in heterogeneous porous media, the Gaussian analysis of one-dimensional unsaturated flow in randomly heterogeneous soils, and the type-curve interpretation of transient single-hole pneumatic injection tests in unsaturated fractured tuffs at the Apache Leap Research Site. Annotation copyrighted by Book News Inc., Portland, OR

Book Flow and Transport Through Unsaturated Fractured Rock

Download or read book Flow and Transport Through Unsaturated Fractured Rock written by Daniel D. Evans and published by American Geophysical Union. This book was released on 2001-01-09 with total page 212 pages. Available in PDF, EPUB and Kindle. Book excerpt: Published by the American Geophysical Union as part of the Geophysical Monograph Series, Volume 42. This monograph is an update and revision of the first edition, Geophysical Monograph 42, on ground-water flow and transport through unsaturated, fractured rock, published by AGU in 1987. The first edition evolved from a special symposium held during the American Geophysical Union fall meetings in San Francisco in December 1986. Invited and contributed papers at that AGU session, as well as panel presentations, focused on conceptualizing, measuring and modeling flow and transport through unsaturated fractured rock. As noted in the preface to the first edition, "the expanded interest in the topic (water flow and contaminant transport through unsaturated fractured rock) was initiated when the U.S. Geological Survey proposed that deep unsaturated zones in arid regions be considered in the site selection for the first high-level, commercially generated radioactive waste repository." Much of the research reported in that first edition was motivated by the U.S. Department of Energy's program to investigate Yucca Mountain at the Nevada Test Site as a possible geologic repository for commercially generated, high-level radioactive waste. As noted in the overview paper of the first edition, "characterization methods and modeling are in their developmental stage with the greatest lack of knowledge being the interaction between fracture and matrix flow and transport properties." Although the first edition of this monograph reflected the state-of-the science, laboratory and field experimental programs were novel and limited and, in general, followed from the principles and methods developed in the soil science community.