YUCCA MOUNTAIN SITE DESCRIPTION (open access)

YUCCA MOUNTAIN SITE DESCRIPTION

The ''Yucca Mountain Site Description'' summarizes, in a single document, the current state of knowledge and understanding of the natural system at Yucca Mountain. It describes the geology; geochemistry; past, present, and projected future climate; regional hydrologic system; and flow and transport within the unsaturated and saturated zones at the site. In addition, it discusses factors affecting radionuclide transport, the effect of thermal loading on the natural system, and tectonic hazards. The ''Yucca Mountain Site Description'' is broad in nature. It summarizes investigations carried out as part of the Yucca Mountain Project since 1988, but it also includes work done at the site in earlier years, as well as studies performed by others. The document has been prepared under the Office of Civilian Radioactive Waste Management quality assurance program for the Yucca Mountain Project. Yucca Mountain is located in Nye County in southern Nevada. The site lies in the north-central part of the Basin and Range physiographic province, within the northernmost subprovince commonly referred to as the Great Basin. The basin and range physiography reflects the extensional tectonic regime that has affected the region during the middle and late Cenozoic Era. Yucca Mountain was initially selected for characterization, in part, …
Date: April 16, 2004
Creator: Simmons, A. M.
Object Type: Report
System: The UNT Digital Library
Characterize Eruptive Processes at Yucca Mountain, Nevada (open access)

Characterize Eruptive Processes at Yucca Mountain, Nevada

This Analysis/Model Report (AMR), ''Characterize Eruptive Processes at Yucca Mountain, Nevada'', presents information about natural volcanic systems and the parameters that can be used to model their behavior. This information is used to develop parameter-value distributions appropriate for analysis of the consequences of volcanic eruptions through a potential repository at Yucca Mountain. Many aspects of this work are aimed at resolution of the Igneous Activity Key Technical Issue (KTI) as identified by the Nuclear Regulatory Commission (NRC 1998, p. 3), Subissues 1 and 2, which address the probability and consequence of igneous activity at the proposed repository site, respectively. Within the framework of the Disruptive Events Process Model Report (PMR), this AMR provides information for the calculations in two other AMRs ; parameters described herein are directly used in calculations in these reports and will be used in Total System Performance Assessment (TSPA). Compilation of this AMR was conducted as defined in the Development Plan, except as noted. The report begins with considerations of the geometry of volcanic feeder systems, which are of primary importance in predicting how much of a potential repository would be affected by an eruption. This discussion is followed by one of the physical and chemical …
Date: December 20, 2001
Creator: Valentine, G.
Object Type: Report
System: The UNT Digital Library
Characterize Eruptive Processes at Yucca Mountain, Nevada (open access)

Characterize Eruptive Processes at Yucca Mountain, Nevada

The purpose of this scientific analysis report, ''Characterize Eruptive Processes at Yucca Mountain, Nevada'', is to present information about natural volcanic systems and the parameters that can be used to model their behavior. This information is used to develop parameter-value distributions appropriate for analysis of the consequences of volcanic eruptions through a repository at Yucca Mountain. This scientific analysis report provides information to four other reports: ''Number of Waste Packages Hit by Igneous Intrusion'', (BSC 2004 [DIRS 170001]); ''Atmospheric Dispersal and Deposition of Tephra from Potential Volcanic Eruption at Yucca Mountain, Nevada'' (BSC 2004 [DIRS 170026]); ''Dike/Drift Interactions'' (BSC 2004 [DIRS 170028]); ''Development of Earthquake Ground Motion Input for Preclosure Seismic Design and Postclosure Performance Assessment of a Geologic Repository at Yucca Mountain, NV'' (BSC 2004 [DIRS 170027], Section 6.5). This report is organized into seven major sections. This section addresses the purpose of this document. Section 2 addresses quality assurance, Section 3 the use of software, Section 4 identifies the requirements that constrain this work, and Section 5 lists assumptions and their rationale. Section 6 presents the details of the scientific analysis and Section 7 summarizes the conclusions reached.
Date: October 4, 2004
Creator: Krier, D.
Object Type: Report
System: The UNT Digital Library
Chlorine-36 alidation Study at Yucca Mountain, Nevada (open access)

Chlorine-36 alidation Study at Yucca Mountain, Nevada

The amount, spatial distribution, and velocity of water percolating through the unsaturated zone (UZ) at Yucca Mountain, Nevada, are important issues for assessing the performance of the proposed deep geologic repository for spent nuclear fuel and high-level radioactive waste. To help characterize the nature and history of UZ flow, isotopic studies were initiated in 1995, using rock samples collected from the Miocene ash-flow tuffs in the Exploratory Studies Facility (ESF), an 8-km-long tunnel constructed along the north-south extent of the repository block, and the Enhanced Characterization of the Repository Block (ECRB) Cross Drift, a 2.5-km-long tunnel constructed across the repository block (Figure 1-1, Sources: Modified from DOE 2002 [Figure 1-14] and USBR 1996). Scientists from Los Alamos National Laboratory (LANL) analyzed for chlorine-36 ({sup 36}Cl) in salts leached from whole-rock samples collected from tunnel walls and subsurface boreholes, and scientists from the U.S. Geological Survey (USGS) analyzed for isotopes of oxygen, carbon, uranium, lead, thorium, and strontium in secondary minerals collected from subsurface fractures and lithophysal cavities. Elevated values for ratios of {sup 36}Cl to total chloride ({sup 36}Cl/CL) at the level of the proposed repository indicated that small amounts of water carrying bomb-pulse {sup 36}Cl (i.e., {sup 36}Cl/Cl ratios …
Date: August 28, 2006
Creator: Paces, J.
Object Type: Report
System: The UNT Digital Library
Cost-Effective Cementitious Material Compatible with Yucca Mountain Repository Geochemistry (open access)

Cost-Effective Cementitious Material Compatible with Yucca Mountain Repository Geochemistry

The current plans for the Yucca Mountain (YM) repository project (YMP) use steel structures to stabilize the disposal drifts and connecting tunnels that are collectively over 100 kilometers in length. The potential exist to reduce the underground construction cost by 100s of millions of dollars and improve the repository's performance. These economic and engineering goals can be achieved by using the appropriate cementitious materials to build out these tunnels. This report describes the required properties of YM compatible cements and reviews the literature that proves the efficacy of this approach. This report also describes a comprehensive program to develop and test materials for a suite of underground construction technologies.
Date: December 17, 2004
Creator: Dole, LR
Object Type: Report
System: The UNT Digital Library
Data Qulaification Report Flowong Interval Data for Use On the Yucca Mountain Project (open access)

Data Qulaification Report Flowong Interval Data for Use On the Yucca Mountain Project

This data qualification report uses technical assessment and corroborating data methods according to Attachment 2 of AP-SIII.2Q, Rev. 0, ICN 2, ''Qualification of Unqualified Data and the Documentation of Rationale for Accepted Data'', to qualify flowing interval data. This report was prepared in accordance with Data Qualification Plan TDP-NBS-GS-000035, Revision 1. Flowing interval location data from borehole tracejector surveys and fracture dip data from acoustic televiewer logging are evaluated in this report. These data were collected under the direction of the U.S. Geological Survey (USGS). The data qualification team considers the data collection protocols of the USGS during the time period of data acquisition to be state-of-the-art. The acoustic televiewer continues to be an important tool for fracture logging and the early methodology for that technique has evolved with little change into the current fracture logging procedure that supports the Yucca Mountain Project (YMP)--approved USGS Quality Assurance Program Plan (QAPP). Consequently, the data collection methods, documentation, and results are reasonable and appropriate in view of standard practice at the time the data were collected. Extensive independent corroborative evidence is available from other borehole survey and logging techniques as well as from independent hydrological pump and injection testing. This evidence supports …
Date: August 3, 2000
Creator: Wilson, C.R. & Grant, T.A.
Object Type: Report
System: The UNT Digital Library
Hydraulic Characterization of Overpressured Tuffs in Central Yucca Flat, Nevada Test Site, Nye County, Nevada (open access)

Hydraulic Characterization of Overpressured Tuffs in Central Yucca Flat, Nevada Test Site, Nye County, Nevada

A sequence of buried, bedded, air-fall tuffs has been used extensively as a host medium for underground nuclear tests detonated in the central part of Yucca Flat at the Nevada Test Site. Water levels within these bedded tuffs have been elevated hundreds of meters in areas where underground nuclear tests were detonated below the water table. Changes in the ground-water levels within these tuffs and changes in the rate and distribution of land-surface subsidence above these tuffs indicate that pore-fluid pressures have been slowly depressurizing since the cessation of nuclear testing in 1992. Declines in ground-water levels concurrent with regional land subsidence are explained by poroelastic deformation accompanying ground-water flow as fluids pressurized by underground nuclear detonations drain from the host tuffs into the overlying water table and underlying regional carbonate aquifer. A hydraulic conductivity of about 3 x 10-6 m/d and a specific storage of 9 x 10-6 m-1 are estimated using ground-water flow models. Cross-sectional and three-dimensional ground-water flow models were calibrated to measured water levels and to land-subsidence rates measured using Interferometric Synthetic Aperture Radar. Model results are consistent and indicate that about 2 million m3 of ground water flowed from the tuffs to the carbonate rock …
Date: October 7, 2005
Creator: Halford, K. J.; Laczniak, R. J. & Galloway, D. L.
Object Type: Report
System: The UNT Digital Library
Review of Microbial Responses to Abiotic Environmental Factors in the Context of the Proposed Yucca Mountain Repository (open access)

Review of Microbial Responses to Abiotic Environmental Factors in the Context of the Proposed Yucca Mountain Repository

A workshop on Microbial Activities at Yucca Mountain (May 1995, Lafayette, CA) was held with the intention to compile information on all pertinent aspects of microbial activity for application to a potential repository at Yucca Mountain. The findings of this workshop set off a number of efforts intended to eventually incorporate the impacts of microbial behavior into performance assessment models. One effort was to expand an existing modeling approach to include the distinctive characteristics of a repository at Yucca Mountain (e.g., unsaturated conditions and a significant thermal load). At the same time, a number of experimental studies were initiated as well as a compilation of relevant literature to more thoroughly study the physical, chemical and biological parameters that would affect microbial activity under Yucca Mountain-like conditions. This literature search (completed in 1996) is the subject of the present document. The collected literature can be divided into four categories: (1) abiotic factors, (2) community dynamics and in-situ considerations, (3) nutrient considerations and (4) transport of radionuclides. The complete bibliography represents a considerable resource, but is too large to be discussed in one document. Therefore, the present report focuses on the first category, abiotic factors, and a discussion of these factors in …
Date: August 1, 2000
Creator: Meike, A. & Stroes-Gascoyne, S.
Object Type: Report
System: The UNT Digital Library
Modeling Approach/Strategy for Corrective Action Unit 97, Yucca Flat and Climax Mine, Revision 0 (open access)

Modeling Approach/Strategy for Corrective Action Unit 97, Yucca Flat and Climax Mine, Revision 0

The objectives of the UGTA corrective action strategy are to predict the location of the contaminant boundary for each CAU, develop and implement a corrective action, and close each CAU. The process for achieving this strategy includes modeling to define the maximum extent of contaminant transport within a specified time frame. Modeling is a method of forecasting how the hydrogeologic system, including the underground test cavities, will behave over time with the goal of assessing the migration of radionuclides away from the cavities and chimneys. Use of flow and transport models to achieve the objectives of the corrective action strategy is specified in the FFACO. In the Yucca Flat/Climax Mine system, radionuclide migration will be governed by releases from the cavities and chimneys, and transport in alluvial aquifers, fractured and partially fractured volcanic rock aquifers and aquitards, the carbonate aquifers, and in intrusive units. Additional complexity is associated with multiple faults in Yucca Flat and the need to consider reactive transport mechanisms that both reduce and enhance the mobility of radionuclides. A summary of the data and information that form the technical basis for the model is provided in this document.
Date: August 2003
Creator: Willie, Janet
Object Type: Report
System: The UNT Digital Library
Analysis of Fracture in Cores from the Tuff Confining Unit beneath Yucca Flat, Nevada Test Site (open access)

Analysis of Fracture in Cores from the Tuff Confining Unit beneath Yucca Flat, Nevada Test Site

The role fractures play in the movement of groundwater through zeolitic tuffs that form the tuff confining unit (TCU) beneath Yucca Flat, Nevada Test Site, is poorly known. This is an important uncertainty, because beneath most of Yucca Flat the TCU lies between the sources of radionuclide contaminants produced by historic underground nuclear testing and the regional carbonate aquifer. To gain a better understanding of the role fractures play in the movement of groundwater and radionuclides through the TCU beneath Yucca Flat, a fracture analysis focusing on hydraulic properties was performed on conventional cores from four vertical exploratory holes in Area 7 of Yucca Flat that fully penetrate the TCU. The results of this study indicate that the TCU is poorly fractured. Fracture density for all fractures is 0.27 fractures per vertical meter of core. For open fractures, or those observed to have some aperture, the density is only 0.06 fractures per vertical meter of core. Open fractures are characterized by apertures ranging from 0.1 to 10 millimeter, and averaging 1.1 millimeter. Aperture typically occurs as small isolated openings along the fracture, accounting for only 10 percent of the fracture volume, the rest being completely healed by secondary minerals. Zeolite …
Date: March 1, 2008
Creator: Prothro, Lance
Object Type: Report
System: The UNT Digital Library
Uncertainty and Sensitivity of Contaminant Travel Times from the Upgradient Nevada Test Site to the Yucca Mountain Area (open access)

Uncertainty and Sensitivity of Contaminant Travel Times from the Upgradient Nevada Test Site to the Yucca Mountain Area

Yucca Mountain (YM), Nevada, has been proposed by the U.S. Department of Energy as the nation’s first permanent geologic repository for spent nuclear fuel and highlevel radioactive waste. In this study, the potential for groundwater advective pathways from underground nuclear testing areas on the Nevada Test Site (NTS) to intercept the subsurface of the proposed land withdrawal area for the repository is investigated. The timeframe for advective travel and its uncertainty for possible radionuclide movement along these flow pathways is estimated as a result of effective-porosity value uncertainty for the hydrogeologic units (HGUs) along the flow paths. Furthermore, sensitivity analysis is conducted to determine the most influential HGUs on the advective radionuclide travel times from the NTS to the YM area. Groundwater pathways are obtained using the particle tracking package MODPATH and flow results from the Death Valley regional groundwater flow system (DVRFS) model developed by the U.S. Geological Survey (USGS). Effectiveporosity values for HGUs along these pathways are one of several parameters that determine possible radionuclide travel times between the NTS and proposed YM withdrawal areas. Values and uncertainties of HGU porosities are quantified through evaluation of existing site effective-porosity data and expert professional judgment and are incorporated in …
Date: September 10, 2009
Creator: Zhu, J.; Pohlmann, K.; Chapman, J.; Russell, C.; Carroll, R.W.H. & Shafer, D.
Object Type: Report
System: The UNT Digital Library
Yucca Mountain, Nevada - A Proposed Geologic Repository for High-Level Radioactive Waste (Volume 1) Introduction (open access)

Yucca Mountain, Nevada - A Proposed Geologic Repository for High-Level Radioactive Waste (Volume 1) Introduction

Yucca Mountain in Nevada represents the proposed solution to what has been a lengthy national effort to dispose of high-level radioactive waste, waste which must be isolated from the biosphere for tens of thousands of years. This chapter reviews the background of that national effort and includes some discussion of international work in order to provide a more complete framework for the problem of waste disposal. Other chapters provide the regional geologic setting, the geology of the Yucca Mountain site, the tectonics, and climate (past, present, and future). These last two chapters are integral to prediction of long-term waste isolation.
Date: September 25, 2006
Creator: Levich, R.A. & Stuckless, J.S.
Object Type: Article
System: The UNT Digital Library
Selected ground-water data for Yucca Mountain region, Southern Nevada and Eastern California, through December 1999 (open access)

Selected ground-water data for Yucca Mountain region, Southern Nevada and Eastern California, through December 1999

Data on ground-water levels, discharges, and withdrawals from a variety of ground-water sources in the study area are reported for calendar year 1999.
Date: October 24, 2001
Creator: Locke, Glenn L.
Object Type: Report
System: The UNT Digital Library
Selected ground-water data for Yucca Mountain region, Southern Nevada and Eastern California, through December 1998 (open access)

Selected ground-water data for Yucca Mountain region, Southern Nevada and Eastern California, through December 1998

Data on ground-water levels, discharges, and withdrawals from a variety of ground-water sources in the study area are reported for calendar year 1998.
Date: October 24, 2001
Creator: Locke, Glenn L.
Object Type: Report
System: The UNT Digital Library
Measurement of the Parameter Kappa, and Reevaluation of Kappa for Small to Moderate Earthquakes at Seismic Stations in the Vicinity of Yucca Mountain, Nevada (open access)

Measurement of the Parameter Kappa, and Reevaluation of Kappa for Small to Moderate Earthquakes at Seismic Stations in the Vicinity of Yucca Mountain, Nevada

The parameter kappa was defined by Anderson and Hough (1984) to describe the high-frequency spectral roll-off of the strong motion seismic spectrum. In the work of Su et al., (1996) the numerical value of kappa estimated for sites near Yucca Mountain was small (~20 ms). The estimate obtained from these events has been applied through a rigorous methodology to develop design earthquake spectra with magnitude over 5.0. Smaller values of kappa lead to higher estimated ground motions in the methodology used by the Probabilistic Seismic Hazard Analysis (PSHA) for Yucca Mountain. An increase of 10 ms in kappa could result in a substantial decrease in the high frequency level of the predicted ground motions. Any parameter that plays such a critical role deserves close examination. Here, we study kappa and its associated uncertainties. The data set used by Su et al (1996) consisted of 12 M 2.8 to 4.5 earthquakes recorded at temporary stations deployed after the June 1992 Little Skull Mountain earthquake. The kappa elements of that study were revisited by Anderson and Su (MOL.20071203.0134) and substantially confirmed. One weakness of those studies is the limited data used. Few of these stations were on tuff or on Yucca Mountain …
Date: December 5, 2007
Creator: Biasi, Glenn & Anderson, John G.
Object Type: Report
System: The UNT Digital Library
SELECTED GROUND-WATER DATA FRO YUCCA MOUNTAIN REGION, SOUTHERN NEVADA AND EASTERN CALIFORNIA, THROUGH DECEMBER 1998 (open access)

SELECTED GROUND-WATER DATA FRO YUCCA MOUNTAIN REGION, SOUTHERN NEVADA AND EASTERN CALIFORNIA, THROUGH DECEMBER 1998

The U.S. Geological Survey, in support of the U.S. Department of Energy, Yucca Mountain Site Characterization Project, collects, compiles, and summarizes hydrologic data in the Yucca Mountain region. The data are collected to allow assessments of ground-water resources during studies to determine the potential suitability of Yucca Mountain for storing high-level nuclear waste. Data on ground-water levels at 34 wells and a fissure (Devils Hole), ground-water discharge at 5 springs and a flowing well, and total reported ground-water withdrawals within Crater Flat, Jackass Flats, Mercury Valley, and the Amargosa Desert are presented for calendar year 1998. Data collected prior to 1998 are graphically presented and data collected by other agencies (or as part of other Geological Survey programs) are included to further indicate variations of ground-water levels, discharges, and withdrawals through time. A statistical summary of ground-water levels at seven wells in Jackass Flats is presented to indicate potential effects of ground-water withdrawals associated with U.S. Department of Energy activities near Yucca Mountain. The statistical summary includes the number of measurements, the maximum, minimum, and median water-level altitudes, and the average deviation of measured water-level altitudes for selected baseline periods and for calendar years 1992-98. At two water-supply wells and …
Date: November 29, 2000
Creator: Groat, Charles G.
Object Type: Report
System: The UNT Digital Library
Analysis of Ground-Water Levels and Associated Trends in Yucca Flat, Nevada Test Site, Nye County, Nevada, 1951-2003 (open access)

Analysis of Ground-Water Levels and Associated Trends in Yucca Flat, Nevada Test Site, Nye County, Nevada, 1951-2003

Almost 4,000 water-level measurements in 216 wells in the Yucca Flat area from 1951 to 2003 were quality assured and analyzed. An interpretative database was developed that describes water-level conditions for each water level measured in Yucca Flat. Multiple attributes were assigned to each water-level measurement in the database to describe the hydrologic conditions at the time of measurement. General quality, temporal variability, regional significance, and hydrologic conditions are attributed for each water-level measurement. The database also includes narratives that discuss the water-level history of each well. Water levels in 34 wells were analyzed for variability and for statistically significant trends. An attempt was made to identify the cause of many of the water-level fluctuations or trends. Potential causes include equilibration following well construction or development, pumping in the monitoring well, withdrawals from a nearby supply well, recharge from precipitation, earthquakes, underground nuclear tests, land subsidence, barometric pressure, and Earth tides. Some of the naturally occurring fluctuations in water levels may result from variations in recharge. The magnitude of the overall water-level change for these fluctuations generally is less than 2 feet. Long-term steady-state hydrographs for most of the wells open to carbonate rock have a very similar pattern. Carbonate-rock …
Date: October 5, 2005
Creator: Fenelon, J.M.
Object Type: Report
System: The UNT Digital Library
Development of Earthquake Ground Motion Input for Preclosure Seismic Design and Postclosure Performance Assessment of a Geologic Repository at Yucca Mountain, NV (open access)

Development of Earthquake Ground Motion Input for Preclosure Seismic Design and Postclosure Performance Assessment of a Geologic Repository at Yucca Mountain, NV

This report describes a site-response model and its implementation for developing earthquake ground motion input for preclosure seismic design and postclosure assessment of the proposed geologic repository at Yucca Mountain, Nevada. The model implements a random-vibration theory (RVT), one-dimensional (1D) equivalent-linear approach to calculate site response effects on ground motions. The model provides results in terms of spectral acceleration including peak ground acceleration, peak ground velocity, and dynamically-induced strains as a function of depth. In addition to documenting and validating this model for use in the Yucca Mountain Project, this report also describes the development of model inputs, implementation of the model, its results, and the development of earthquake time history inputs based on the model results. The purpose of the site-response ground motion model is to incorporate the effects on earthquake ground motions of (1) the approximately 300 m of rock above the emplacement levels beneath Yucca Mountain and (2) soil and rock beneath the site of the Surface Facilities Area. A previously performed probabilistic seismic hazard analysis (PSHA) (CRWMS M&O 1998a [DIRS 103731]) estimated ground motions at a reference rock outcrop for the Yucca Mountain site (Point A), but those results do not include these site response effects. …
Date: November 5, 2004
Creator: Wong, I.
Object Type: Report
System: The UNT Digital Library
Data Qualification Report: Flow Meter Survey Data From Borehole UE-25c#3 For Use On The Yucca Mountain Project (open access)

Data Qualification Report: Flow Meter Survey Data From Borehole UE-25c#3 For Use On The Yucca Mountain Project

This Data Qualification Report uses corroborating data methods according to Attachment 2 of AP-SIII.2Q, Rev. 00, ICN 3, ''Qualification of Unqualified Data and the Documentation of Rationale for Accepted Data'', to qualify flowing interval data from a borehole spinner log. This report was prepared in accordance with Data Qualification Plan DQP-NBS-GS-000005, Rev. 00. These data were collected under the Yucca Mountain Site Characterization Project (YMP) Quality Assurance Requirements and Description (QARD) document but are unqualified because unqualified software was used in data reduction. The unqualified flow log was run in Borehole UE-25c No.3 in 1995. Corroborative evidence is available from independent flow logs run in the same borehole in 1984 by an earlier investigator. This corroborative support is unusually strong because it represents a second measurement of the same data. The corroborating data agree well with the data being qualified and support the adequacy of the data. The unqualified software, the TERRASTATION code by Terrasciences Inc., is widely used and accepted by the technical community for non-project applications. The widespread acceptance of the software further supports the adequacy of the data. In view of the evidence provided by the corroborating data and general acceptance of the software, the Data Qualification …
Date: February 28, 2001
Creator: Wilson, C.
Object Type: Report
System: The UNT Digital Library
Long-Term Mechanical Behavior of Yucca Mountain Tuff and its Variability, Final Technical Report for Task ORD-FY04-021 (open access)

Long-Term Mechanical Behavior of Yucca Mountain Tuff and its Variability, Final Technical Report for Task ORD-FY04-021

The study of the long term mechanical behavior of Yucca Mountain tuffs is important for several reasons. Long term stability of excavations will affect accessibility (e.g. for inspection purposes), and retrievability. Long term instabilities may induce loading of drip shields and/or emplaced waste, thus affecting drip shield and/or waste package corrosion. Failure of excavations will affect airflow, may affect water flow, and may affect temperature distributions. The long term mechanical behavior of rocks remains an elusive topic, loaded with uncertainties. A variety of approaches have been used to improve the understanding of this complex subject, but it is doubtful that it has reached a stage where firm predictions can be considered feasible. The long term mechanical behavior of "soft" rocks, especially evaporites, and in particular rock salt, has been the subject of numerous investigations (e.g. Cristescu and Hunsche, 1998, Cristescu et al, 2002), and basic approaches towards engineering taking into account the long term behavior of such materials have long been well established (e.g. Dreyer, 1972, 1982). The same is certainly not true of "hard" rocks. While it long has been recognized that the long term strength of ?hard? rocks almost certainly is significantly less than that measured during "short", …
Date: March 20, 2006
Creator: Daemen, Jaak J. K.; Ma, Lumin & Zhao, Guohua
Object Type: Report
System: The UNT Digital Library
Well ER-6-1 Tracer Test Analysis: Yucca Flat, Nevada Test Site, Nye County, Nevada, Rev. No.: 0 (open access)

Well ER-6-1 Tracer Test Analysis: Yucca Flat, Nevada Test Site, Nye County, Nevada, Rev. No.: 0

The ER-6-1 multiple-well aquifer test-tracer test (MWAT-TT) investigated groundwater flow and transport processes relevant to the transport of radionuclides from sources on the Nevada Test Site (NTS) through the lower carbonate aquifer (LCA) hydrostratigraphic unit (HSU). The LCA, which is present beneath much of the NTS, is the principal aquifer for much of southern Nevada. This aquifer consists mostly of limestone and dolomite, and is pervasively fractured. Groundwater flow in this aquifer is primarily in the fractures, and the hydraulic properties are primarily related to fracture frequency and fracture characteristics (e.g., mineral coatings, aperture, connectivity). The objective of the multiple-well aquifer test (MWAT) was to determine flow and hydraulic characteristics for the LCA in Yucca Flat. The data were used to derive representative flow model and parameter values for the LCA. The items of specific interest are: Hydraulic conductivity; Storage parameters; Dual-porosity behavior; and Fracture flow characteristics. The objective of the tracer transport experiment was to evaluate the transport properties and processes of the LCA and to derive representative transport parameter values for the LCA. The properties of specific interest are: Effective porosity; Matrix diffusion; Longitudinal dispersivity; Adsorption characteristics; and Colloid transport characteristics. These properties substantially control the rate of …
Date: September 1, 2006
Creator: Ruskauff, Greg
Object Type: Report
System: The UNT Digital Library
Geochemical and Isotopic Evaluation of Groundwater Movement in Corrective Action Unit 97: Yucca Flat/Climax Mine, Nevada Test Site, Nevada, Rev. No.: 0 (open access)

Geochemical and Isotopic Evaluation of Groundwater Movement in Corrective Action Unit 97: Yucca Flat/Climax Mine, Nevada Test Site, Nevada, Rev. No.: 0

This report describes the results of a comprehensive geochemical evaluation of the groundwater flow system in the Yucca Flat/Climax Mine Corrective Action Unit (CAU). The main objectives of this study are to identify probable pathways for groundwater flow within the study area and to develop constraints on groundwater transit times between selected data collection sites. This work provides an independent means of testing and verifying predictive flow models being developed for this CAU using finite element methods. The Yucca Flat/Climax Mine CAU constitutes the largest of six underground test areas on the Nevada Test Site (NTS) specified for remedial action in the ''Federal Facility Agreement and Consent Order''. A total of 747 underground nuclear detonations were conducted in this CAU. Approximately 23 percent of these detonations were conducted below or near the water table, resulting in groundwater contamination in the vicinity and possibly downgradient of these underground test locations. Therefore, a rigorous evaluation of the groundwater flow system in this CAU is necessary to assess potential long-term risks to the public water supply at downgradient locations.
Date: February 1, 2006
Creator: Farnham, Irene
Object Type: Report
System: The UNT Digital Library
A Hydrostratigraphic Model and Alternatives for the Groundwater Flow and Contaminant Transport Model of Corrective Action Unit 97: Yucca Flat-Climax Mine, Lincoln and Nye Counties, Nevada (open access)

A Hydrostratigraphic Model and Alternatives for the Groundwater Flow and Contaminant Transport Model of Corrective Action Unit 97: Yucca Flat-Climax Mine, Lincoln and Nye Counties, Nevada

A new three-dimensional hydrostratigraphic framework model for the Yucca Flat-Climax Mine Corrective Action Unit was completed in 2005. The model area includes Yucca Flat and Climax Mine, former nuclear testing areas at the Nevada Test Site, and proximal areas. The model area is approximately 1,250 square kilometers in size and is geologically complex. Yucca Flat is a topographically closed basin typical of many valleys in the Basin and Range province. Faulted and tilted blocks of Tertiary-age volcanic rocks and underlying Proterozoic and Paleozoic sedimentary rocks form low ranges around the structural basin. During the Cretaceous Period a granitic intrusive was emplaced at the north end of Yucca Flat. A diverse set of geological and geophysical data collected over the past 50 years was used to develop a structural model and hydrostratigraphic system for the basin. These were integrated using EarthVision? software to develop the 3-dimensional hydrostratigraphic framework model. Fifty-six stratigraphic units in the model area were grouped into 25 hydrostratigraphic units based on each unit's propensity toward aquifer or aquitard characteristics. The authors organized the alluvial section into 3 hydrostratigraphic units including 2 aquifers and 1 confining unit. The volcanic units in the model area are organized into 13 hydrostratigraphic …
Date: January 1, 2006
Creator: Nevada, Geotechnical Sciences Group Bechtel
Object Type: Report
System: The UNT Digital Library