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Hydrogeology of the unsaturated zone, Yucca Mountain, Nevada

Description: The unsaturated volcanic tuff beneath Yucca Mountain, Nevada, is being evaluated by the US Department of Energy as a host rock for a potential mined geologic repository for high-level radioactive waste. Assessment of site suitability needs an efficient and focused investigative program. A conceptual hydrogeologic model that simulates the flow of fluids through the unsaturated zone at Yucca Mountain was developed to guide the program and to provide a basis for preliminary assessment of site suitability. The study was made as part of the Nevada Nuclear Waste Storage Investigations Project of the US Department of Energy. Thickness of the unsaturated zone is about 1640 to 2460 feet (500 to 750 meters). Based on physical properties, the rocks in the unsaturated zone are grouped for the purpose of this paper into five informal hydrogeologic units. From top to bottom these units are: Tiva Canyon welded unit, Paintbrush nonwelded unit. Topopah Spring welded unit, Calico Hills nonwelded unit, and Crater Flat unit. Welded units have a mean fracture density of 8 to 40 fractures per unit cubic meter, mean matrix porosities of 12 to 23%, matrix hydraulic conductivities with geometric means ranging from 6.5 x 10{sup -6} to 9.8 x 10{sup -6} foot per day (2 x 10{sup -6} to 3 x 10{sup -6} meter per day), and bulk hydraulic conductivities of 0.33 to 33 feet per day (0.1 to 10 meters per day). The nonwelded units have a mean fracture density of 1 to 3 fractures per unit cubic meter, mean matrix porosities of 31 to 46%, and saturated hydraulic conductivities with geometric means ranging from 2.6 x 10{sup -5} to 2.9 x 10{sup -2} foot per day (8 x 10{sup -6} to 9 x 10{sup -3} meter per day). 15 refs., 4 figs., 1 tab.
Date: December 31, 1985
Creator: Montazer, P. & Wilson, W.E.
Partner: UNT Libraries Government Documents Department

Three-dimensional hydrological and thermal property models of Yucca Mountain, Nevada

Description: This report describes the creation of three-dimensional numerical models of selected rock-matrix properties for the region of the potential high-level nuclear waste repository site at Yucca Mountain, which is located in southern Nevada. The models have been generated for a majority of the unsaturated and shallow saturated zone within an area referred to within the Yucca Mountain Site Characterization project as the site area. They comprise a number of material properties of importance both to detailed process-level modeling activities and to more summary-style performance assessment modeling. The material properties within these models are both spatially variable (heterogeneous) and spatially correlated, as the rocks are understood from data obtained from site-characterization drill holes widely scattered across the site area.
Date: November 1, 1997
Creator: Rautman, C.A. & McKenna, S.A.
Partner: UNT Libraries Government Documents Department

Bulk, thermal, and mechanical properties of the Topopah Spring Member of the Paintbrush Tuff, Yucca Mountain, Nevada

Description: Experimental data on matrix porosity, grain density, thermal expansion, compressive strength, Young`s modulus, Poisson`s ratio, and axial strain at failure for samples from the Topopah Spring Member of the Paintbrush Tuff are compiled. Heat capacity and emissivity also are discussed. Data have been analyzed for spatial variability; slight variability is observed for matrix porosity, grain density, and thermal expansion coefficient. Estimates of in situ values for some properties, such as bulk density and heat capacity, are presented. Vertical in situ stress as a function of horizontal and vertical location has been calculated. 96 refs., 37 figs., 27 tabs.
Date: September 1, 1987
Creator: Nimick, F.B. & Schwartz, B.M.
Partner: UNT Libraries Government Documents Department

Thermal conductivity, bulk properties, and thermal stratigraphy of silicic tuffs from the upper portion of hole USW-G1, Yucca Mountain, Nye County, Nevada

Description: Thermal-conductivity and bulk-property measurements were made on welded and nonwelded silicic tuffs from the upper portion of Hole USW-G1, located near the southwestern margin of the Nevada Test Site. Bulk-property measurements were made by standard techniques. Thermal conductivities were measured at temperatures as high as 280{sup 0}C, confining pressures to 10 MPa, and pore pressures to 1.5 MPa. Extrapolation of measured saturated conductivities to zero porosity suggests that matrix conductivity of both zeolitized and devitrified tuffs is independent of stratigraphic position, depth, and probably location. This fact allows development of a thermal-conductivity stratigraphy for the upper portion of Hole G1. Estimates of saturated conductivities of zeolitized nonwelded tuffs and devitrified tuffs below the water table appear most reliable. Estimated conductivities of saturated densely welded devitrified tuffs above the water table are less reliable, due to both internal complexity and limited data presently available. Estimation of conductivity of dewatered tuffs requires use of different air thermal conductivities in devitrified and zeolitized samples. Estimated effects of in-situ fracturing generally appear negligible.
Date: March 1, 1982
Creator: Lappin, A.R.; VanBuskirk, R.G.; Enniss, D.O.; Buters, S.W.; Prater, F.M.; Muller, C.B. et al.
Partner: UNT Libraries Government Documents Department

Water permeability and related rock properties measured on core samples from the Yucca Mountain USW GU-3/G-3 and USW G-4 boreholes, Nevada Test Site, Nevada

Description: Core samples were measured for bulk density, grain density, porosity, resistivity, and water permeability as part of a comprehensive geologic investigation designed to determine the suitability of Yucca Mountain as a site for the containment of high-level radioactive waste products. The cores were selected at the drill sites so as to be representative of the major lithologic variations observed within stratigraphic units of the Paintbrush Tuff, Calico Hills Tuff, Crater Flat Tuff, Lithic Ridge Tuff, and Older Tuffs. Dry and saturated bulk density, grain density, and porosity measurements were made on the core samples principally to establish that a reasonable uniformity exists in the textural and mineral character of the sample pairs. Electrical resistivity measured on sample pairs tended to be lower along the plane transverse to the vertical axis of the drill core herein referred to as the horizontal plane. Permeability values, ranging from virtually zero (<.02 microdarcies) to over 200 millidarcies, also indicate a preferential flow direction along the horizontal plane of the individual tuff units. Permeability decreases with flow duration in all but the non-welded tuffs as unconsolidated particles within the pore network are repositioned so as to impede the continued flow of water through the rock. Reversing flow direction initially restores the permeability of the rock to its original or maximum value.
Date: September 1, 1994
Creator: Anderson, L.A.
Partner: UNT Libraries Government Documents Department

An experimental comparison of laboratory techniques in determining bulk properties of tuffaceous rocks; Yucca Mountain Site Characterization Project

Description: Samples of tuffaceous rock were studied as part of the site characterization for a potential nuclear waste repository at Yucca Mountain in southern Nevada. These efforts were scoping in nature, and their results, along with those of other investigations, are being used to develop suitable procedures for determining bulk properties of tuffaceous rock in support of thermal and mechanical properties evaluations. Comparisons were made between various sample preparation, handling, and measurement techniques for both zeolitized and nonzeolitized tuff in order to assess their effects on bulk property determinations. Laboratory tests included extensive drying regimes to evaluate dehydration behavior, the acquisition of data derived from both gas and water pycnometers to compare their suitability in determining grain densities, a comparison of particle size effects, and a set of experiments to evaluate whole core saturation methods. The results affirm the added complexity of these types of measurements where there is a zeolite component in the sample mineralogy. Absolute values for the bulk properties of zeolitized tuff are immeasurable due to the complex nature of their dehydration behavior. However, the results of the techniques that were investigated provide a basis for the development of preferred, consistent methods for determining the grain density, dry and saturated bulk densities, and porosity of tuffaceous rock, including zeolitic tuff in support of thermal and mechanical properties evaluations.
Date: April 1, 1994
Creator: Boyd, P.J.; Martin, R.J. III & Price, R.H.
Partner: UNT Libraries Government Documents Department

Results of rock property measurements made on core samples from Yucca Mountain boreholes, Nevada Test Site, Nevada; Part 1, Boreholes UE25A-4, -5, -6, and -7; Part 2, Borehole UE25PNo.1

Description: Laboratory measurements of resistivity, bulk and grain density, porosity, compressional sonic velocity, water permeability, magnetic susceptibility, and remanent magnetization were made on core samples from Yucca Mountain boreholes located in Drill Hole Wash at the Nevada Test Site. The samples are representative of lithologic variations to be found in the Tiva Canyon, Yucca Mountain, Pah Canyon, and the upper Topopah Spring Members of the Paintbrush Tuff. Boreholes penetrated to a depth of approximately 152 meters (500 ft.). The Paintbrush Tuff consists primarily of nonwelded to densely welded rhyolitic ash-flow tuff with relatively thin beds of ash-fall tuff typically separating each Member. Resistivity and bulk density measurements were made on samples containing natural pore waters and repeated following resaturation with local tap water. Density comparisons indicate the samples to be undersaturated in their natural environment as expected in that the boreholes did not intersect the water table.
Date: December 31, 1991
Creator: Anderson, L.A.
Partner: UNT Libraries Government Documents Department

Diffusive Barrier and Getter Under Waste Packages VA Reference Design Feature Evaluations

Description: This technical document evaluates those aspects of the diffusive barrier and getter features which have the potential for enhancing the performance of the Viability Assessment Reference Design and are also directly related to the key attributes for the repository safety strategy of that design. The effects of advection, hydrodynamic dispersion, and diffusion on the radionuclide migration rates through the diffusive barrier were determined through the application of the one-dimensional, advection/dispersion/diffusion equation. The results showed that because advective flow described by the advection-dispersion equation dominates, the diffusive barrier feature alone would not be effective in retarding migration of radiocuclides. However, if the diffusive barrier were combined with one or more features that reduced the potential for advection, then transport of radionuclides would be dominated by diffusion and their migration from the EBS would be impeded. Apatite was chosen as the getter material used for this report. Two getter configurations were developed, Case 1 and Case 2. As in the evaluation of the diffusive barrier, the effects of advection, hydrodynamic dispersion, and diffusion on the migration of radionuclides through the getter are evaluated. However, in addition to these mechanisms, the one-dimensional advection/dispersion/diffusion model is modified to include the effect of sorption on radionuclide migration rates through the sorptive medium (getter). As a result of sorption, the longitudinal dispersion coefficient, and the average linear velocity are effectively reduced by the retardation factor. The retardation factor is a function of the getter material's dry bulk density, sorption coefficient and moisture content. The results of the evaluation showed that a significant delay in breakthrough through the getter can be achieved if the thickness of the getter barrier is increased.
Date: May 24, 1999
Creator: MacNeil, K.
Partner: UNT Libraries Government Documents Department

Enhancing the soil organic matter pool through biomass incorporation.

Description: A study was installed in the Upper Coastal Plain of South Carolina, USA, that sought to examine the impact of incorporating downed slash materials into subsoil layers on soil chemical and physical properties as compared with the effect of slash materials left on the soil surface. Baseline levels of slash were estimated by establishing transects within harvested stands and estimating the quantity of down wood and stumps. An equivalent quantity of biomass and two times the baseline levels were incorporated into subsurface soil layers by a CMI RS 500B reclaimer/stabilizer. Two sites were examined which differed in soil textural composition: sandy vs. clay. Site differences had no impact on machine productivity and machine costs were estimated at $US 521 ha-1 and $US 633 ha-1 on the ''sandy'' and ''clay'' sites, respectively. The feasibility of the CM1 for biomass incorporation is low due to high unit area costs but increased machine productivity would reduce costs and improve its potential. Biomass incorporation improved carbon and nutrient content of each site, especially on the sandy site. Slash levels had an impact on nutrient content but the differences were not statistically significant. For the sandy site, improvements in soil physical properties were evident in response to incorporation and machine planting operations. Bulk density and soil strength were reduced in response to biomass incorporation and tillage to levels that would not limit root production. The differences in soil physical response between incorporated treatments were minimal and not statistically significant.
Date: June 11, 2003
Creator: Sanchez, Felipe, G.; Carter, Emily, A. & Klepac, John, F.
Partner: UNT Libraries Government Documents Department

Soil-Related Input Parameters for the Biosphere Model

Description: This report presents one of the analyses that support the Environmental Radiation Model for Yucca Mountain Nevada (ERMYN). The ''Biosphere Model Report'' (BSC 2004 [DIRS 169460]) describes the details of the conceptual model as well as the mathematical model and the required input parameters. The biosphere model is one of a series of process models supporting the postclosure Total System Performance Assessment (TSPA) for the Yucca Mountain repository. A schematic representation of the documentation flow for the Biosphere input to TSPA is presented in Figure 1-1. This figure shows the evolutionary relationships among the products (i.e., analysis and model reports) developed for biosphere modeling, and the biosphere abstraction products for TSPA, as identified in the ''Technical Work Plan for Biosphere Modeling and Expert Support'' (TWP) (BSC 2004 [DIRS 169573]). This figure is included to provide an understanding of how this analysis report contributes to biosphere modeling in support of the license application, and is not intended to imply that access to the listed documents is required to understand the contents of this report. This report, ''Soil-Related Input Parameters for the Biosphere Model'', is one of the five analysis reports that develop input parameters for use in the ERMYN model. This report is the source documentation for the six biosphere parameters identified in Table 1-1. The purpose of this analysis was to develop the biosphere model parameters associated with the accumulation and depletion of radionuclides in the soil. These parameters support the calculation of radionuclide concentrations in soil from on-going irrigation or ash deposition and, as a direct consequence, radionuclide concentration in other environmental media that are affected by radionuclide concentrations in soil. The analysis was performed in accordance with the TWP (BSC 2004 [DIRS 169573]) where the governing procedure was defined as AP-SIII.9Q, ''Scientific Analyses''. This analysis revises the previous ...
Date: September 9, 2004
Creator: Smith, A. J.
Partner: UNT Libraries Government Documents Department

Geologic Investigation of a Potential Site for a Next-Generation Reactor Neutrino Oscillation Experiment -- Diablo Canyon, San Luis Obispo County, CA

Description: This report provides information on the geology and selected physical and mechanical properties of surface rocks collected at Diablo Canyon, San Luis Obispo County, California as part of the design and engineering studies towards a future reactor neutrino oscillation experiment. The main objective of this neutrino project is to study the process of neutrino flavor transformation or neutrino oscillation by measuring neutrinos produced in the fission reactions of a nuclear power plant. Diablo Canyon was selected as a candidate site because it allows the detectors to be situated underground in a tunnel close to the source of neutrinos (i.e., at a distance of several hundred meters from the nuclear power plant) while having suitable topography for shielding against cosmic rays. The detectors have to be located underground to minimize the cosmic ray-related background noise that can mimic the signal of reactor neutrino interactions in the detector. Three Pliocene-Miocene marine sedimentary units dominate the geology of Diablo Canyon: the Pismo Formation, the Monterey Formation, and the Obispo Formation. The area is tectonically active, located east of the active Hosgri Fault and in the southern limb of the northwest trending Pismo Syncline. Most of the potential tunnel for the neutrino detector lies within the Obispo Formation. Review of previous geologic studies, observations from a field visit, and selected physical and mechanical properties of rock samples collected from the site provided baseline geological information used in developing a preliminary estimate for tunneling construction cost. Gamma-ray spectrometric results indicate low levels of radioactivity for uranium, thorium, and potassium. Grain density, bulk density, and porosity values for these rock samples range from 2.37 to 2.86 g/cc, 1.41 to 2.57 g/cc, and 1.94 to 68.5 percent respectively. Point load, unconfined compressive strength, and ultrasonic velocity tests were conducted to determine rock mechanical and acoustic properties. The ...
Date: June 11, 2004
Creator: Onishi, Celia Tiemi; Dobson, Patrick; Nakagawa, Seiji; Glaser, Steven & Galic, Dom
Partner: UNT Libraries Government Documents Department

Tank 38H Saltcake Core and Supernate Sample Analysis

Description: This report provides details of the characterization of Tank 38H saltcake and supernate samples pulled in September 2003. The core sample HTF-E-03-114 contained approximately 4 inches of saltcake, which was soupy and brown with white chunks, and contained less than 15 mL of cloudy free liquid. The undrained bulk saltcake had a water content of 16.8 percentage weight and a bulk density that was approximately 1.94 g/cm3 at full saturation. The 137Cs activity of the bulk saltcake in sample HTF-E-03-114 was 3.72E+7 pCi/g, which corresponds to 0.3 Ci per gallon of saltcake. The 238Pu activity of the bulk saltcake was 3.62E+6 pCi/g. The filtered free liquid in sample HTF-E-03-114 had a density of 1.430 g/cm3, a 137Cs activity of 0.73 Ci/gal., and a 238Pu activity of 5.78E+3 pCi/mL. The solids filtered from the HTF-E-03-114 free liquid were primarily composed of salts (sodium nitrate and sodium carbonate monohydrate) and sodium aluminosilicates. The Tank 38H supernate samples (HTF-E-03-122 and 123) had a density of 1.45 g/cm3, a 137Cs activity of 0.65 Ci/gal, a 238Pu activity of 2.2E4 pCi/mL, and contained no visible insoluble solids. The viscosity of supernate samples HTF-E-03-122 and 123 was determined at 25 degrees Celsius, 35 degrees Celsius, and 50 degrees Celsius to be 12.1 cP, 8.1 cP, and 5.1 cP, respectively. An exponential correlation for the Tank 38H supernate viscosity was formulated for use over this temperature range. In the undrained saltcake sample, several components, including cesium, nitrite, hydroxide, phosphate, formate, and potassium, were partitioned predominantly into the interstitial liquid. Although the plutonium, uranium, neptunium, and strontium activities in the Tank 38H saltcake core sample are high compared with recent Tank 41H samples, they are low compared with previous saltcake samples from Tank 38H collected in July 2000 and July 2001. The 137Cs of the Tank 38H saltcake ...
Date: July 7, 2004
Creator: MARTINO, CHRISTOPHERJ
Partner: UNT Libraries Government Documents Department

A finite difference model used to predict the consolidation of a ceramic waste form produced from the electrometallurgical treatment of spent nuclear fuel.

Description: Argonne National Laboratory (ANL) has developed a process to immobilize waste salt containing fission products, uranium, and transuranic elements as chlorides in a glass-bonded ceramic waste form. This salt was generated in the electrorefining operation used in the electrometallurgical treatment of spent Experimental Breeder Reactor-II (EBR-II) fuel. The ceramic waste process culminates with an elevated temperature operation. The processing conditions used by the furnace, for demonstration scale and production scale operations, are to be developed at Argonne National Laboratory-West (ANL-West). To assist in selecting the processing conditions of the furnace and to reduce the number of costly experiments, a finite difference model was developed to predict the consolidation of the ceramic waste. The model accurately predicted the heating as well as the bulk density of the ceramic waste form. The methodology used to develop the computer model and a comparison of the analysis to experimental data is presented.
Date: March 29, 2004
Creator: Bateman, K. J. & Capson, D. D.
Partner: UNT Libraries Government Documents Department

Geologic Investigation of a Potential Site for a Next-Generation Reactor Neutrino Oscillation Experiment -- Diablo Canyon, San Luis Obispo County, CA

Description: This report provides information on the geology and selected physical and mechanical properties of surface rocks collected at Diablo Canyon, San Luis Obispo County, California as part of the design and engineering studies towards a future reactor neutrino oscillation experiment. The main objective of this neutrino project is to study the process of neutrino flavor transformation--or neutrino oscillation--by measuring neutrinos produced in the fission reactions of a nuclear power plant. Diablo Canyon was selected as a candidate site because it allows the detectors to be situated underground in a tunnel close to the source of neutrinos (i.e., at a distance of several hundred meters from the nuclear power plant) while having suitable topography for shielding against cosmic rays. The detectors have to be located underground to minimize the cosmic ray-related background noise that can mimic the signal of reactor neutrino interactions in the detector. Three Pliocene-Miocene marine sedimentary units dominate the geology of Diablo Canyon: the Pismo Formation, the Monterey Formation, and the Obispo Formation. The area is tectonically active, located east of the active Hosgri Fault and in the southern limb of the northwest trending Pismo Syncline. Most of the potential tunnel for the neutrino detector lies within the Obispo Formation. Review of previous geologic studies, observations from a field visit, and selected physical and mechanical properties of rock samples collected from the site provided baseline geological information used in developing a preliminary estimate for tunneling construction cost. Gamma-ray spectrometric results indicate low levels of radioactivity for uranium, thorium, and potassium. Grain density, bulk density, and porosity values for these rock samples range from 2.37 to 2.86 g/cc, 1.41 to 2.57 g/cc, and 1.94 to 68.5% respectively. Point load, unconfined compressive strength, and ultrasonic velocity tests were conducted to determine rock mechanical and acoustic properties. The rock strength values ...
Date: August 1, 2004
Creator: Onishi, Celia Tiemi; Dobson, Patrick; Nakagawa, Seiji; Glaser, Steven & Galic, Dom
Partner: UNT Libraries Government Documents Department

Quantifying Vadose Zone Flow and Transport Uncertainties Using a Unified, Hierarchical Approach

Description: The objective of this research is to develop and demonstrate a general approach for modeling flow and transport in the heterogeneous vadose zone. The approach uses similar media scaling, geostatistics, and conditional simulation methods to estimate soil hydraulic parameters at unsampled locations from field-measured water content data and scale-mean hydraulic parameters determined from available site characterization data. Neural network methods are being developed to estimate soil hydraulic parameters from more easily measured physical property data such as bulk density, organic matter content, and percentages of sand, silt, and clay (or particle-size distributions). Field water content distributions are being estimated using various geophysical methods including neutron moderation, ground-penetrating radar, and electrical resistance tomography. One of the primary goals of this research is to determine relationships between the type of data used in model parameterization, the quantity of data available, the scale of the measurement, and the uncertainty in predictions of flow and transport using these methods. Evaluation of the relationships between available data, scale, and uncertainty are using data from a large-scale, controlled field experiment.
Date: June 1, 2002
Creator: Meyer, Philip D.; Murray, Christopher J.; Rockhold, Mark L. & Schaap, Marcel
Partner: UNT Libraries Government Documents Department

CO{sub 2} SEQUESTRATION POTENTIAL OF TEXAS LOW-RANK COALS

Description: The objectives of this project are to evaluate the feasibility of carbon dioxide (CO{sub 2}) sequestration in Texas low-rank coals and to determine the potential for enhanced coalbed methane (CBM) recovery as an added benefit of sequestration. There were three main objectives for this reporting period, which related to obtaining accurate parameters for reservoir model description and modeling reservoir performance of CO{sub 2} sequestration and enhanced coalbed methane recovery. The first objective was to collect and desorb gas from 10 sidewall core coal samples from an Anadarko Petroleum Corporation well (APCL2 well) at approximately 6,200-ft depth in the Lower Calvert Bluff Formation of the Wilcox Group in east-central Texas. The second objective was to measure sorptive capacities of these Wilcox coal samples for CO{sub 2}, CH{sub 4}, and N{sub 2}. The final objective was to contract a service company to perform pressure transient testing in Wilcox coal beds in a shut-in well, to determine permeability of deep Wilcox coal. Bulk density of the APCL2 well sidewall core samples averaged 1.332 g/cc. The 10 sidewall core samples were placed in 4 sidewall core canisters and desorbed. Total gas content of the coal (including lost gas and projected residual gas) averaged 395 scf/ton on an as-received basis. The average lost gas estimations were approximately 45% of the bulk sample total gas. Projected residual gas was 5% of in-situ gas content. Six gas samples desorbed from the sidewall cores were analyzed to determine gas composition. Average gas composition was approximately 94.3% methane, 3.0% ethane, and 0.7% propane, with traces of heavier hydrocarbon gases. Carbon dioxide averaged 1.7%. Coal from the 4 canisters was mixed to form one composite sample that was used for pure CO{sub 2}, CH{sub 4}, and N{sub 2} isotherm analyses. The composite sample was 4.53% moisture, 37.48% volatile matter, 9.86% ...
Date: February 1, 2005
Creator: McVay, Duane A.; Jr, Walter B. Ayers & Jensen, Jerry L.
Partner: UNT Libraries Government Documents Department

Rock Properties Model

Description: The purpose of this model report is to document the Rock Properties Model version 3.1 with regard to input data, model methods, assumptions, uncertainties and limitations of model results, and qualification status of the model. The report also documents the differences between the current and previous versions and validation of the model. The rock properties model provides mean matrix and lithophysae porosity, and the cross-correlated mean bulk density as direct input to the ''Saturated Zone Flow and Transport Model Abstraction'', MDL-NBS-HS-000021, REV 02 (BSC 2004 [DIRS 170042]). The constraints, caveats, and limitations associated with this model are discussed in Section 6.6 and 8.2. Model validation accomplished by corroboration with data not cited as direct input is discussed in Section 7. The revision of this model report was performed as part of activities being conducted under the ''Technical Work Plan for: The Integrated Site Model, Revision 05'' (BSC 2004 [DIRS 169635]). The purpose of this revision is to bring the report up to current procedural requirements and address the Regulatory Integration Team evaluation comments. The work plan describes the scope, objectives, tasks, methodology, and procedures for this process.
Date: September 16, 2004
Creator: Lum, C.
Partner: UNT Libraries Government Documents Department

An Exact Solution for the Assessment of Nonequilibrium Sorption of Radionuclides in the Vadose Zone

Description: In a report on model evaluation, the authors ran the HYDRUS Code, among other transport codes, to evaluate the impacts of nonequilibrium sorption sites on the time-evolution of 99Tc and 90Sr through the vadose zone. Since our evaluation was based on a rather low, annual recharge rate, many of the numerical results derived from HYDRUS indicated that the nonequilibrium sorption sites, in essence, acted as equilibrium sorption sites. To help explain these results, we considered a ''stripped-down'' version of the HYDRUS system. This ''stripped-down'' version possesses two dependent variables, one for the radionuclides in solution and the other for the radionuclides adsorbed to the nonequilibrium sites; and it possesses constant physical parameters. The resultant governing equation for the radionuclides in solution is a linear, advection-dispersion-reaction (i.e., radioactive decay) partial differential equation containing a history integral term accounting for the nonequilibrium sorption sites. It is this ''stripped-down'' version, which is the subject of this paper. We found an exact solution to this new version of the model. The exact solution is given in terms of a single definite integral of terms involving elementary functions of the independent variables and the system parameters. This integral possesses adequate convergence properties and is easy to evaluate, both in a quantitative matter and in a qualitative manner. The parameters that are considered in the system are as follows: the radionuclide's equilibrium partition coefficient between water and soil, the bulk density of the soil, the fractions of equilibrium/nonequilibrium sorption sites, the volumetric water content, the first order equilibrium adsorption rate constant, the first order radioactive decay rate constant, the liquid water soil tortuosity factor, the molecular diffusion coefficient in water, the longitudinal dispersivity factor, and the Darcian fluid flux density. In addition, the system possesses a stepwise, variable source of radionuclides at the ground surface and ...
Date: February 26, 2002
Creator: Drake, R. L. & Chen, J-S.
Partner: UNT Libraries Government Documents Department

Quantifying Vadose Zone Flow and Transport Uncertainties Using a Unified, Hierarchical Approach

Description: The objective of this research is to develop and demonstrate a general approach for modeling flow and transport in the heterogeneous vadose zone. The approach uses similar media scaling, geostatistics, and conditional simulation methods to estimate soil hydraulic parameters at unsampled locations from field-measured water content data and scale-mean hydraulic parameters determined from available site characterization data. Neural network methods are being developed to estimate soil hydraulic parameters from more easily measured physical property data such as bulk density, organic matter content, and percentages of sand, silt, and clay (or particle-size distributions). Field water content distributions are being estimated using various geophysical methods including neutron moderation, ground-penetrating radar, and electrical resistance tomography. One of the primary goals of this research is to determine relationships between the type of data used in model parameterization, th e quantity of data available, the scale of the measurement, and the uncertainty in predictions of flow and transport using these methods. Evaluation of the relationships between available data, scale, and uncertainty will use primarily existing data from large-scale, controlled experiments.
Date: June 1, 2001
Creator: Meyer, Philip D.; Murray, Chris J. & Rockhold, Mark L.
Partner: UNT Libraries Government Documents Department

Birch's law and the properties of high temperature fluid metals

Description: By comparing acoustic velocities in fluid metals over a very wide range of densities we have established Birch's Law as an approximate representation over the entire liquid range. For a given liquid metal the acoustic velocity is close to linear in density, with a slope determined by the atomic weight. The measurements include isobaric expansion to less than half normal density, ultrasonics on molten metals at 1 atmosphere, and shock-melted metals to greater than twice normal density. We also find unusual behavior of the Gruneisen gamma, which can be explained in terms of simple fluid models. 15 refs.
Date: January 1, 1987
Creator: Shaner, J.W.
Partner: UNT Libraries Government Documents Department

Geohydrologic data from test hole USW UZ-6s, Yucca Mountain, Nye County, Nevada

Description: As part of the investigation of Yucca Mountain, Nevada, as a potential site for storing high-level radioactive wastes in an underground mined geologic repository, the US Geological Survey, in cooperation with the US Department of Energy, in 1982, began drilling a series of test holes in and near the southwestern part of the Nevada Test Site to determine the geologic and hydrologic characteristics of the area. Test hole USW UZ-6s is part of that series of test holes, and this report presents data obtained from test hole USW UZ-6s. The data includes those from drilling operations, lithology, coring, and laboratory analyses of hydrologic properties, which include gravimetric water content, water potential, and bulk- and grain-density values. The gravimetric water content of the densely welded section of the Tiva Canyon Member of the Paintbrush Tuff averages 0.027 gram per gram for test hole USW UZ-6s; water potential averages {minus}7,200 kilo-pascals; gravimetric water content of the moderately to densely welded tuffs range from 0.054 gram per gram for the Tiva Canyon Member of the Paintbrush Tuff to 0.027 gram per gram for the Topopah Spring Member of the Paintbrush Tuff; and water potentials range from {minus}6,700 to {minus}3,400 kilopascals. Gravimetric water content for the partially welded to unnamed bedded tuffs average 0.123, 0.106, and 0.085 gram per gram for the Tiva Canyon Member, the unnamed bedded tuffs, and the Topopah Spring Member in test hole USW UZ-6s; average water potentials for these units are {minus}1,700, {minus}480, and {minus}820 kilopascals.
Date: December 31, 1993
Creator: Loskot, C.L.
Partner: UNT Libraries Government Documents Department

Statistical Analysis and Geologic Evaluation of Laboratory-Derived Physical Property Data for Selected Nevada Test Site Core Samples of Non-Zeolitized Tuffs

Description: A statistical analysis and geologic evaluation of recently acquired laboratory-derived physical property data are being performed to better understand and more precisely correlate physical properties with specific geologic parameters associated with non-zeolitized tuffs at the Nevada Test Site. Physical property data include wet and dry bulk density, grain density (i.e., specific gravity), total porosity, and effective porosity. Geologic parameters utilized include degree of welding, lithology, stratigraphy, geographic area, and matrix mineralogy (i.e., vitric versus devitrified). Initial results indicate a very good correlation between physical properties and geologic parameters such as degree of welding, lithology, and matrix mineralogy. However, physical properties appear to be independent of stratigraphy and geographic area, suggesting that the data are transferrable with regards to these two geologic parameters. Statistical analyses also indicate that the assumed grain density of 2.65 grams per cubic centimeter used to calculate porosity in some samples is too high. This results in corresponding calculated porosity values approximately 5 percent too high (e.g., 45 percent versus 40 percent), which can be significant in the lower porosity rocks. Similar analyses and evaluations of zeolitic tuffs and carbonate rock physical properties data are ongoing as well as comparisons to geophysical log values.
Date: April 20, 2009
Creator: National Security Technologies, LLC
Partner: UNT Libraries Government Documents Department

Preliminary studies of a continuous process for the thermal decomposition of uranyl nitrate hexahydrate

Description: At the request of the A.E.C., experiments were conducted on the continuous addition of liquid UNH to a bed of powdered UO{sub 3} in a gas heated pot in the Pot Room of Plant 6 to gather thermal data regarding the continuous decomposition of UNH and to make observations of the physical behavior of such a system. The thermal data indicate that the size and the energy requirements of the equipment required per pound of UO{sub 3} produced would be considerably smaller than for the present batch-wise process. The products of the reactions through all the successive stages were more dense than the products of the present process. The metal yields in the reduction stage were 98.5%, 97.6% and 97.8%. The yield of 98.5% in the one reactor indicates that this process will produce UF{sub 4} capable of producing as high yields as any yet made. The lower yields in the other two cases fall within the present control limits for yield. The determination of the physical and chemical properties has not yet been completed and will be reported shortly in a subsequent paper.
Date: December 7, 1950
Creator: Shelley, W.
Partner: UNT Libraries Government Documents Department

Comparing soil carbon of short rotation poplar plantations with agricultural crops and woodlots in north central United States.

Description: Atmospheric carbon dioxide (CO2) has increased dramatically since the beginning of the Industrial Revolution as a result of human activities (Keeling and others 1995, Houghton and others 2001). The primary cause of CO2 increases are worldwide fossil fuel burning, biomass burning, and cement manufacturing. These activities are, in turn, tied to the expanding world population and a rising demand for energy. If the steady increase of CO2 continues, there may be profound effects on the environment and the world economy from a "greenhouse effect" that has led to global warming of the atmosphere (Houghton and others 2001).
Date: March 1, 2004
Creator: Coleman, Mark D.; Isebrands, J.G.; Tolsted, David N. & Tolbert, Virginia R.
Partner: UNT Libraries Government Documents Department