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Final Technical Report: Effects of Changing Water and Nitrogen Inputs on a Mojave Desert Ecosystem

Description: Questions addressed under this grant shared the common hypothesis that plant and ecosystem performance will positively respond to the augmentation of the most limiting resources to plant growth in the Mojave Desert, e.g., water and nitrogen. Specific hypothesis include (1) increased summer rainfall will significantly increase plant production thorugh an alleviation of moisture stress in the dry summer months, (2) N-deposition will increase plan production in this N-limited system, particularly in wet years or in concert with added summer rain, and (3) biological crust disturbance will gradually decrease bio-available N, with concomitant long-term reductions in photosynthesis and ANPP. Individual plan and ecosystem responses to global change may be regulated by biogeochemical processes and natural weather variability, and changes in plant and ecosystem processes may occur rapidly, may occur only after a time lag, or may not occur at all. During the first PER grant period, we observed changes in plant and ecosystem processes that would fall under each of these time-response intervals: plant and ecosystem processes responded rapidly to added summer rain, whereas most processes responded slowly or in a lag fashion to N-deposition and with no significant response to crust disturbance. Therefore, the primary objectives of this renewal grant were to: (1) continue ongoing measurements of soil and plant parameters that assess primary treatment responses; (2) address the potential heterogeneity of soil properties and (3) initiate a new suite of measurements that will provide data necessary for scaling/modeling of whole-plot to ecosystem-level responses. Our experimental approach included soil plan-water interactions using TDR, neutron probe, and miniaturized soil matric potential and moisture sensors, plant ecophysiological and productivity responses to water and nitrogen treatments and remote sensing methodologies deployed on a radio control platform.
Date: November 30, 2007
Creator: Smith, Stanley D. & Nowak, Robert S.
Partner: UNT Libraries Government Documents Department

Biotic Processes Regulating the Carbon Balance of Desert Ecosystems - Final Report

Description: Our results from the 10-year elevated atmospheric CO{sub 2} concentration study at the Nevada Desert FACE (Free-air CO{sub 2} Enrichment) Facility (NDFF) indicate that the Mojave Desert is a dynamic ecosystem with the capacity to respond quickly to environmental changes. The Mojave Desert ecosystem is accumulating carbon (C), and over the 10-year experiment, C accumulation was significantly greater under elevated [CO{sub 2}] than under ambient, despite great fluctuations in C inputs from year to year and even apparent reversals in which [CO{sub 2}] treatment had greater C accumulations.
Date: December 13, 2012
Creator: Nowak, Robert S; Smith, Stanley D; Evans, Dave; Ogle, Kiona & Fenstermaker, Lynn
Partner: UNT Libraries Government Documents Department

Effects of Elevated CO2 on Root Function and Soil Respiration in a Mojave Desert Ecosystem

Description: Increases in atmospheric CO{sub 2} concentration during the last 250 years are unequivocal, and CO{sub 2} will continue to increase at least for the next several decades (Houghton et al. 2001, Keeling & Whorf 2002). Arid ecosystems are some of the most important biomes globally on a land surface area basis, are increasing in area at an alarming pace (Dregne 1991), and have a strong coupling with regional climate (Asner & Heidebrecht 2005). These water-limited ecosystems also are predicted to be the most sensitive to elevated CO{sub 2}, in part because they are stressful environments where plant responses to elevated CO{sub 2} may be amplified (Strain & Bazzaz 1983). Indeed, all C{sub 3} species examined at the Nevada Desert FACE Facility (NDFF) have shown increased A{sub net} under elevated CO{sub 2} (Ellsworth et al. 2004, Naumburg et al. 2003, Nowak et al. 2004). Furthermore, increased shoot growth for individual species under elevated CO{sub 2} was spectacular in a very wet year (Smith et al. 2000), although the response in low to average precipitation years has been smaller (Housman et al. 2006). Increases in perennial cover and biomass at the NDFF are consistent with long term trends in the Mojave Desert and elsewhere in the Southwest, indicating C sequestration in woody biomass (Potter et al. 2006). Elevated CO{sub 2} also increases belowground net primary production (BNPP), with average increases of 70%, 21%, and 11% for forests, bogs, and grasslands, respectively (Nowak et al. 2004). Although detailed studies of elevated CO{sub 2} responses for desert root systems were virtually non-existent prior to our research, we anticipated that C sequestration may occur by desert root systems for several reasons. First, desert ecosystems exhibit increases in net photosynthesis and primary production at elevated CO{sub 2}. If large quantities of root litter enter the ecosystem ...
Date: December 19, 2007
Creator: Nowak, Robert S.
Partner: UNT Libraries Government Documents Department

Energetic Photon and Electron Interactions With Positive Ions

Description: The objective of this research is a deeper understanding of the complex multi-electron interactions that govern inelastic processes involving positive ions in plasma environments, such as those occurring in stellar cares and atmospheres, x-ray lasers, thermonuclear fusion reactors and materials-processing discharges. In addition to precision data on ionic structure and transition probabilities, high resolution quantitative measurements of ionization test the theoretical methods that provide critical input to computer codes used for plasma modeling and photon opacity calculations. Steadily increasing computational power and a corresponding emphasis on simulations gives heightened relevance to precise and accurate benchmark data. Photons provide a highly selective probe of the internal electronic structure of atomic and molecular systems, and a powerful means to better understand more complex electron-ion interactions.
Date: July 1, 2013
Creator: Phaneuf, Ronald A.
Partner: UNT Libraries Government Documents Department

Investigations of the Fundamental Surface Reactions Involved in the Sorption and Desorption of Radionuclides

Description: Models for describing solution- and surface-phase reactions have been used for 30 years, but only recently applicable to complex surfaces. Duff et al., using micro-XANES, found that Pu was concentrated on Mn-oxide and smectite phases of zeolitic tuff, providing an evaluation of contaminant speciation on surfaces for modeling. Experiments at Los Alamos demonstrated that actinides display varying surface residence time distributions, probably reflective of mineral surface heterogeneity. We propose to investigate the sorption/desorption behavior of radionuclides from mineral surfaces, as effected by microorganisms, employing isolates from Nevada Test Site deep alluvium as a model system. Characterizations will include surface area, particle size distribution, x-ray diffraction (XRD), microprobe analysis, extractions, and microbiology. Surface interactions will be assessed by electron spectroscopy (XPS), x-ray absorption fine structure spectroscopy (XAFS), X-ray emission spectroscopy, transmission electron microscopy (TEM) and Scanning electron microscopy (SEM). Desert Research Institute (DRI), University of Nevada, Reno (UNR), and University of Nevada, Las Vegas (UNLV) researchers will collaborate to enhance scientific infrastructure and the understanding of contaminant behavior on surfaces, with broader implications for the management of DOE sites.
Date: April 20, 2011
Creator: Czerwinski, Ken; Heske, Clemens; Moser, Duane; Misra, Mnoranjan & McMillion, Glen
Partner: UNT Libraries Government Documents Department

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

Description: 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", i.e. standard (ASTM D 2938), ISRM suggested (Bieniawski et al, 1978) and conventionally used test procedures (e.g. Bieniawski, 1970, Wawersik, 1972, Hoek and Brown, 1980, p. 150), what limited approaches have been taken to develop strategies toward determining the long term mechanical behavior of "hard" rock remain in the early research and investigation stage, at best. One early model developed specifically for time dependent analysis of underground "hard" rock structures is the phenomenological model by Kaiser and Morgenstern (1981). Brady and Brown (1985, p. 93) state that over a wide range of strain rates, from 10^-8 to 10^2/s the difference ...
Date: March 20, 2006
Creator: Daemen, Jaak J. K.; Ma, Lumin & Zhao, Guohua
Partner: UNT Libraries Government Documents Department

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

Description: 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 itself. A decade of Southern Great Basin Digital Seismic Network (SGBDSN) recording has now yielded a larger body of on-scale, well calibrated digital ground motion records suitable for investigating kappa. We use the SGBDSN data to check some of the original assumptions, improve the statistical confidence of the conclusions, and determine values of kappa for stations on or near Yucca Mountain. The outstanding issues in kappa analysis, as they apply to Yucca Mountain, include: 1. The number itself. The kappa estimate near 20 msec from Su et al. (1996) and Anderson and Su (MOL.20071203.0134) is markedly smaller than is considered ...
Date: December 5, 2007
Creator: Biasi, Glenn & Anderson, John G.
Partner: UNT Libraries Government Documents Department

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

Description: 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 ...
Date: August 14, 2007
Creator: Ye, Ming; Pan, Feng; Hu, Xiaolong & Zhu, Jianting
Partner: UNT Libraries Government Documents Department

Groundwater Flow and Thermal Modeling to Support a Preferred Conceptual Model for the Large Hydraulic Gradient North of Yucca Mountain

Description: The purpose of this study is to report on the results of a preliminary modeling framework to investigate the causes of the large hydraulic gradient north of Yucca Mountain. This study builds on the Saturated Zone Site-Scale Flow and Transport Model (referenced herein as the Site-scale model (Zyvoloski, 2004a), which is a three-dimensional saturated zone model of the Yucca Mountain area. Groundwater flow was simulated under natural conditions. The model framework and grid design describe the geologic layering and the calibration parameters describe the hydrogeology. The Site-scale model is calibrated to hydraulic heads, fluid temperature, and groundwater flowpaths. One area of interest in the Site-scale model represents the large hydraulic gradient north of Yucca Mountain. Nearby water levels suggest over 200 meters of hydraulic head difference in less than 1,000 meters horizontal distance. Given the geologic conceptual models defined by various hydrogeologic reports (Faunt, 2000, 2001; Zyvoloski, 2004b), no definitive explanation has been found for the cause of the large hydraulic gradient. Luckey et al. (1996) presents several possible explanations for the large hydraulic gradient as provided below: The gradient is simply the result of flow through the upper volcanic confining unit, which is nearly 300 meters thick near the large gradient. The gradient represents a semi-perched system in which flow in the upper and lower aquifers is predominantly horizontal, whereas flow in the upper confining unit would be predominantly vertical. The gradient represents a drain down a buried fault from the volcanic aquifers to the lower Carbonate Aquifer. The gradient represents a spillway in which a fault marks the effective northern limit of the lower volcanic aquifer. The large gradient results from the presence at depth of the Eleana Formation, a part of the Paleozoic upper confining unit, which overlies the lower Carbonate Aquifer in much of the Death ...
Date: December 18, 2007
Creator: McGraw, D. & Oberlander, P.
Partner: UNT Libraries Government Documents Department

Results of Chemical Analyses for Alcove 8/Niche 3 Tracer Studies

Description: This is the final report detailing the analyses performed under ORD-FY04-011 "Chemical Analyses for Alcove 8/Niche 3 Tracer Studies." The work was performed under the University and Community College System of Nevada (UCCSN) and the Department of Energy (DOE) Cooperative Agreement Number DE-FC28-04RW12232. This task provided method development and analytical support for the Alcove 8/Niche 3 Tracer Studies in the Exploratory Studies Facility (ESF). Concentrations of tracers, as well as major anions and cations, were reported for samples provided by Lawrence Berkeley National Laboratory (LBNL) and the US Geological Survey (USGS). Samples were analyzed using High Performance Liquid Chromatography (HPLC) and Ion Chromatography (IC). Samples were analyzed and controlled according to Implementing Procedures (IP's) written and approved in accordance with the Office of Civilian Radioactive Waste Management (OCRWM) approved Nevada System of Higher Education (NSHE) Quality Assurance Program.
Date: February 23, 2006
Creator: Daniels, Jeanette
Partner: UNT Libraries Government Documents Department

Initial Borehole Accelerometer Array Observations Near the North Portal of the ESF

Description: This report addresses observed ground motions at the site of the proposed surface facilities associated with the designated repository for high-level nuclear waste at Yucca Mountain, Nevada. In 2003 an accelerometer array was installed at three boreholes on the pad of the north portal of the ESF (Exploratory Studies Facility) at Yucca Mountain, Nevada, by the Nevada Seismological Laboratory (NSL). These boreholes, roughly 150 m apart and initially used for extensive geological and geophysical surveys, were ideal locations to measure the subsurface ground motions at the proposed site of surface facilities such as the Waste Handling Building. Such measurements will impact the design of the facilities. Accelerometer emplacement depths of approximately 15 m from the surface and then at the bottom of the boreholes, roughly 100 m, were chosen. Accelerometers were also placed at the surface next to the boreholes, for a total of nine accelerometers, all three-component. Data recording was accomplished with onsite recorders, with the onsite data transmitted to a central computer at a trailer on the pad. All requirements were met to qualify these data as ''Q''. Due to the lack of significant recordings during 2003, several low signal-to-noise (S/N) quality events were chosen for processing. The maximum horizontal peak ground acceleration (PGA) recorded at the pad was approximately 1 cm/s2 in 2003; the corresponding peak ground velocity (PGV) was approximately 0.01 cm/s. PGA and PGV were obtained at all nine accelerometers for most of these events, and spectra were computed. Ground motion amplitudes varied significantly across the boreholes. Higher ground amplifications were observed at the surface for the two boreholes that penetrated a thick amount ({approx} 30 m) of fill and Quaternary alluvium compared to the one that had less than 2 m of such. Additionally, surface-to-deep recordings showed as much as a factor of five ...
Date: August 17, 2005
Creator: von Seggern, David
Partner: UNT Libraries Government Documents Department

Ground Water Level Measurements in Selected Boreholes Near the Site of the Proposed Repository

Description: The Harry Reid Center for Environmental Studies (HRC) at the University of Nevada, Las Vegas (UNLV) acquired quarterly and continuous data on water levels from approximately 26 boreholes that comprise a periodic monitoring network (Table 1) between October 2003 and September 2007. During this period we continued to observe and analyze short and long-term ground water level trends in periodically monitored boreholes. In this report we summarize and discuss four key findings derived from analysis of water level data acquired during this period: 1. Rapid ground water level rise after storm events in Forty Mile Canyon; 2. Seismically-induced ground water level fluctuations; 3. A sample of synoptic observations and barometric influences on short term fluctuations; and 4. Long term ground water level trends observed from mid-2001 through late-2005.
Date: November 29, 2007
Creator: Page, H. Scott
Partner: UNT Libraries Government Documents Department

Influence of Lithophysal Geometry on the Uniaxial Compression of Tuff-Like Rock

Description: A large portion of the rock of the high-level nuclear waste repository at Yucca Mountain contains lithophysae or voids. These voids have a significant detrimental effect on the engineering properties of the rock mass and its performance. The lithophysae were formed at the time of volcanic deposition by pockets of gas trapped within the compressing and cooling pyroclastic flow material. Lithophysae vary by size, shape, and spatial frequency of occurrence. Due to the difficulties of testing actual lithophysal rock, the current mechanical property data set is limited and the numerical models of lithophysal rock are not well validated. The purpose of this task was to experimentally quantify the effect of void geometry in the mechanical compression of cubes of analog lithophysal-like rock. In this research the mechanical properties of the analog rock were systematically studied by examining various patterns of voids based on variables consisting of hole shape, size, and geometrical distribution. Each specified hole pattern was cast into 6 by 6 by 6-in. Hydro-StoneTB® specimens (produced in triplicate) and then tested under uniaxial compression. Solid Hydro-StoneTB® specimens exhibited similar mechanical properties to those estimated for rock mass solid specimens of Topopah Spring tuff. The results indicated that the compressive strength and Young’s Modulus values decrease with increasing specimen void porosity. The modulus and strength with void porosity relationships are essentially linear over the 5 to 20 percent void porosity range. When zero void porosity (solid specimen) results are added, exponential functions do not provide a good fit to the data due to a significant sensitivity of strength and modulus to the presence of macro-sized voids. From solid specimens there is roughly a 60 percent drop in strength with about 7 percent void porosity, increasing to an 80 percent drop at about 20 percent void porosity. The percent change in ...
Date: June 13, 2007
Creator: Rigby, Douglas B.
Partner: UNT Libraries Government Documents Department

Results of Chemical Analyses in Support of Yucca Mountain Studies

Description: Ground water monitoring for the Nye County Early Warning Drilling Program (NCEWDP) was established to monitor underground water sources of the area and to protect communities surrounding the Nevada Test Site (NTS) from potential radionuclide contamination of these water sources. It provides hydrological information pertaining to groundwater flow patterns and recharge issues in the vicinity of Yucca Mountain. The Harry Reid Center for Environmental Studies (HRC) obtained groundwater samples from select NCEWDP wells shown in Figure 1. These samples were analyzed for major cations, major anions, trace elements, rare earth elements, alkalinity, pH and conductivity. These geochemical results can be used to evaluate the degree of interaction between the aquifers sampled, leading to a thorough mapping of the aquifer system. With increased analysis down gradient of the Yucca Mountain area, evaluations can identify viable groundwater flow paths and establish mixing of the groundwater systems. Tracer tests provide insight into groundwater flow characteristics and transport processes of potential contaminants. These tests are important for contaminant migration issues including safe disposal of hazardous and radioactive materials and remediation of potentially released contaminants. At a minimum, two conservative (non-sorbing) tracers with different diffusion coefficients are used for each tracer test. The tracer test performed under this cooperative agreement utilized fluorinated benzoic acids and halides as conservative tracers. The tracers are of differing size and have differing rates of diffusion into the rock. Larger molecules can not enter the pore spaces that are penetrated by the smaller molecules, therefore larger tracers will travel faster through thegroundwater system. Identical responses of the two tracers indicate no appreciable diffusion into pores of the aquifer system tuff. For the Nye County Tracer Tests, the HRC provided chemical analysis for the tracer test being conducted at site 22. Samples were analyzed for multiple tracers throughout the testing period.
Date: December 11, 2007
Creator: Daniels, Jeanette
Partner: UNT Libraries Government Documents Department

Bomb-Pulse Chlorine-36 at the Proposed Yucca Mountain Repository Horizon: An Investigation of Previous Conflicting Results and Collection of New Data

Description: Previous studies Los Alamos National Laboratory (LANL) found elevated ratios of chlorine-36 to total chloride (36Cl/Cl) in samples of rock collected from the Exploratory Studies Facility (ESF) at Yucca Mountain (YM). The data were interpreted as an indication that fluids containing “bomb-pulse” 36Cl reached the repository horizon in the ~50 years since the peak period of above-ground nuclear testing. Due to the significance of 36Cl data to conceptual models of unsaturated zone flow, the United States Geological Survey (USGS) implemented a study to validate the LANL findings. The USGS drilled new boreholes at select locations across zones where bomb-pulse ratios had previously been identified. The drill cores were analyzed at Lawrence Livermore National Laboratory (LLNL). Because consensus was not reached between the USGS/LLNL and LANL on several fundamental points including the presence or absence of bomb-pulse 36Cl, an evaluation by the University of Nevada, Las Vegas (UNLV), was initiated. The overall objectives of the UNLV study were to investigate the source of the validation study’s conflicting results, and to obtain additional data on bomb-pulse isotopes at the repository horizon. UNLV engaged in discussions with previous investigators, reviewed reports, and analyzed archived samples. UNLV also collected new samples of rock from the ESF, soil profiles from the surface of YM, and samples of seep water from inside the ESF. Samples were analyzed for 36Cl/Cl ratios, and 99Tc and 129I in select samples. A column experiment was conducted mimicking the passage of bomb-pulse 36Cl through YM tuff. The work faced several obstacles including an extended shutdown of the tunnel. Only one sample yielded a background corrected 36Cl/Cl ratio that was higher than the accepted bomb-pulse threshold (1250 x 10-15). Specimen 01034214 obtained from the Drill Hole Wash fault (19+33) had a ratio of 1590 ± 80 (1σ) x10-15, whereas the other separate ...
Date: July 31, 2006
Creator: Cizdziel, James
Partner: UNT Libraries Government Documents Department

Yucca Mountain Climate Technical Support Representative

Description: The primary objective of Project Activity ORD-FY04-012, “Yucca Mountain Climate Technical Support Representative,” was to provide the Office of Civilian Radioactive Waste Management (OCRWM) with expertise on past, present, and future climate scenarios and to support the technical elements of the Yucca Mountain Project (YMP) climate program. The Climate Technical Support Representative was to explain, defend, and interpret the YMP climate program to the various audiences during Site Recommendation and License Application. This technical support representative was to support DOE management in the preparation and review of documents, and to participate in comment response for the Final Environmental Impact Statement, the Site Recommendation Hearings, the NRC Sufficiency Comments, and other forums as designated by DOE management. Because the activity was terminated 12 months early and experience a 27% reduction in budget, it was not possible to complete all components of the tasks as originally envisioned. Activities not completed include the qualification of climate datasets and the production of a qualified technical report. The following final report is an unqualified summary of the activities that were completed given the reduced time and funding.
Date: October 23, 2007
Creator: Sharpe, Saxon E.
Partner: UNT Libraries Government Documents Department

Seismicity in the Vicinity of Yucca Mountain, Nevada, for the Period October 1, 2004 to September 30, 2006

Description: This report describes earthquake activity within approximately 65 km of Yucca Mountain site during the October 1, 2004 to September 30, 2006 time period (FY05-06). The FY05-06 earthquake activity will be compared with the historical and more recent period of seismic activity in the Yucca Mountain region. The relationship between the distribution of seismicity and active faults, historical patterns of activity, and rates of earthquakes (number of events and their magnitudes) are important components in the assessment of the seismic hazard for the Yucca Mountain site. Since October 1992 the University of Nevada has compiled a catalog of earthquakes in the Yucca Mountain area. Seismicity reports have identified notable earthquake activity, provided interpretations of the seismotectonics of the region, and documented changes in the character of earthquake activity based on nearly 30 years of site-characterization monitoring. Data from stations in the seismic network in the vicinity of Yucca Mountain is collected and managed at the Nevada Seismological Laboratory (NSL) at the University of Nevada Reno (UNR). Earthquake events are systematically identified and cataloged under Implementing Procedures developed in compliance with the Nevada System of Higher Education (NSHE) Quality Assurance Program. The earthquake catalog for FY05-06 in the Yucca Mountain region submitted to the Yucca Mountain Technical Data Management System (TDMS) forms the basis of this report.
Date: November 26, 2007
Creator: Smith, Ken
Partner: UNT Libraries Government Documents Department

Exceptional Ground Accelerations and Velocities Caused by Earthquakes

Description: This project aims to understand the characteristics of the free-field strong-motion records that have yielded the 100 largest peak accelerations and the 100 largest peak velocities recorded to date. The peak is defined as the maximum magnitude of the acceleration or velocity vector during the strong shaking. This compilation includes 35 records with peak acceleration greater than gravity, and 41 records with peak velocities greater than 100 cm/s. The results represent an estimated 150,000 instrument-years of strong-motion recordings. The mean horizontal acceleration or velocity, as used for the NGA ground motion models, is typically 0.76 times the magnitude of this vector peak. Accelerations in the top 100 come from earthquakes as small as magnitude 5, while velocities in the top 100 all come from earthquakes with magnitude 6 or larger. Records are dominated by crustal earthquakes with thrust, oblique-thrust, or strike-slip mechanisms. Normal faulting mechanisms in crustal earthquakes constitute under 5% of the records in the databases searched, and an even smaller percentage of the exceptional records. All NEHRP site categories have contributed exceptional records, in proportions similar to the extent that they are represented in the larger database.
Date: January 17, 2008
Creator: Anderson, John
Partner: UNT Libraries Government Documents Department

Second Generation Waste Package Design Study

Description: The following describes the objectives of Project Activity 023 “Second Generation Waste Package Design Study” under DOE Cooperative Agreement DE-FC28-04RW12232. The objectives of this activity are: to review the current YMP baseline environment and establish corrosion testenvironments representative of the range of dry to intermittently wet conditions expected in the drifts as a function of time; to demonstrate the oxidation and corrosion resistance of A588 weathering steel and reference Alloy 22 samples in the representative dry to intermittently dry conditions; and to evaluate backfill and design features to improve the thermal performance analyses of the proposed second-generation waste packages using existing models developed at the University of Nevada, Reno(UNR). The work plan for this project activity consists of three major tasks: Task 1. Definition of expected worst-case environments (humidity, liquid composition and temperature) at waste package outer surfaces as a function of time, and comparison with environments defined in the YMP baseline; Task 2. Oxidation and corrosion tests of proposed second-generation outer container material; and Task 3. Second Generation waste package thermal analyses. Full funding was not provided for this project activity.
Date: June 28, 2007
Creator: Armijo, J. S.; Misra, M. & Kar, Piyush
Partner: UNT Libraries Government Documents Department

Seismicity in the Vicinity of Yucca Mountain, Nevada, for the Period October 1, 2003 to September 30, 2004

Description: This report describes the seismicity and earthquake monitoring activities within the Yucca Mountain region during fiscal year 2004 (FY2004 - October 1, 2003, through September 30, 2004) based on operation of the Southern Great Basin Digital Seismic Network (SGBDSN). Network practices and earthquake monitoring conducted at the Nevada Seismological Laboratory (NSL) under DOE directives for prior fiscal years are covered in similar yearly reports (see references). Real-time systems, including regional data telemetry and data management at NSL, provide for the automatic determination of earthquake locations and magnitudes and notification of important earthquakes in the region to UNR staff and DOE management. All waveform and meta-data, including automatic locations, phase arrival information, and analyst reviewed information, are managed through a relational database system allowing quick and reliable evaluation and analysis of ongoing earthquake activity near Yucca Mountain. This network, which contains weak-motion and strong-motion instrumentation, addresses the seismic hazard of the Yucca Mountain area by providing accurate earthquake magnitudes for earthquake recurrence estimates, spatial hypocentral control to very low magnitudes for identifying and assessing active faults and verifying tectonic models, true ground motions over the complete range of expected earthquake amplitudes for developing predictive models, and earthquake source information for characterizing active faulting. The Nevada Seismological Laboratory operated a 30-station monitoring network within a ring of approximately 50 km radius around Yucca Mountain during FY2004. This year showed the second-lowest seismic moment rate in the NTS and Yucca Mountain region for any fiscal year reporting period since prior to the 1992 M 5.6 Little Skull Mountain (LSM) earthquake. A total of 2180 earthquakes were located for FY2004. The largest event during FY2004 was M 2.99 and there were only 12 earthquakes greater than M 2.00. This is the second year since the LSM event that no M ≥ 3.00 earthquake was ...
Date: October 15, 2007
Creator: von Seggern, David & Smith, Ken
Partner: UNT Libraries Government Documents Department

Precarious Rock Methodology for Seismic Hazard: Physical Testing, Numerical Modeling and Coherence Studies

Description: This report covers the following projects: Shake table tests of precarious rock methodology, field tests of precarious rocks at Yucca Mountain and comparison of the results with PSHA predictions, study of the coherence of the wave field in the ESF, and a limited survey of precarious rocks south of the proposed repository footprint. A series of shake table experiments have been carried out at the University of Nevada, Reno Large Scale Structures Laboratory. The bulk of the experiments involved scaling acceleration time histories (uniaxial forcing) from 0.1g to the point where the objects on the shake table overturned a specified number of times. The results of these experiments have been compared with numerical overturning predictions. Numerical predictions for toppling of large objects with simple contact conditions (e.g., I-beams with sharp basal edges) agree well with shake-table results. The numerical model slightly underpredicts the overturning of small rectangular blocks. It overpredicts the overturning PGA for asymmetric granite boulders with complex basal contact conditions. In general the results confirm the approximate predictions of previous studies. Field testing of several rocks at Yucca Mountain has approximately confirmed the preliminary results from previous studies, suggesting that he PSHA predictions are too high, possibly because the uncertainty in the mean of the attenuation relations. Study of the coherence of wavefields in the ESF has provided results which will be very important in design of the canisters distribution, in particular a preliminary estimate of the wavelengths at which the wavefields become incoherent. No evidence was found for extreme focusing by lens-like inhomogeneities. A limited survey for precarious rocks confirmed that they extend south of the repository, and one of these has been field tested.
Date: September 29, 2006
Creator: Anooshehpoor, Rasool; Purvance, Matthew D.; Brune, James N.; Preston, Leiph A.; Anderson, John G. & Smith, Kenneth D.
Partner: UNT Libraries Government Documents Department

Seismicity in the Vicinity of Yucca Mountain, Nevada, for the Period October 1, 2002, to September 30, 2003

Description: Earthquake activity in the Yucca Mountain from October 1, 2002 through September 30, 2003 (FY03) is assessed and compared with previous activity in the region. FY03 is the first reporting year since the 1992 M 5.6 Little Skull Mountain earthquake with no earthquakes greater than M 3.0 within 65 km of Yucca Mountain. In addition, FY03 includes the fewest number of earthquakes greater than M 2.0 in any reporting year since the LSM event. With 3075 earthquakes in the catalog, FY03 represents the second largest number of earthquakes (second to FY02) since FY96 when digital seismic network operations began. The largest event during FY03 was M 2.78 in eastern NTS and there were only 8 earthquakes greater than M 2.0.
Date: December 4, 2007
Creator: Smith, Ken & von Seggern, David
Partner: UNT Libraries Government Documents Department

Yucca Mountain Area Saturated Zone Dissolved Organic Carbon Isotopic Data

Description: Groundwater samples in the Yucca Mountain area were collected for chemical and isotopic analyses and measurements of water temperature, pH, specific conductivity, and alkalinity were obtained at the well or spring at the time of sampling. For this project, groundwater samples were analyzed for major-ion chemistry, deuterium, oxygen-18, and carbon isotopes of dissolved inorganic carbon (DIC) and dissolved organic carbon (DOC). The U.S. Geological Survey (USGS) performed all the fieldwork on this project including measurement of water chemistry field parameters and sample collection. The major ions dissolved in the groundwater, deuterium, oxygen-18, and carbon isotopes of dissolved inorganic carbon (DIC) were analyzed by the USGS. All preparation and processing of samples for DOC carbon isotopic analyses and geochemical modeling were performed by the Desert Research Institute (DRI). Analysis of the DOC carbon dioxide gas produced at DRI to obtain carbon-13 and carbon-14 values was conducted at the University of Arizona Accelerator Facility (a NSHE Yucca Mountain project QA qualified contract facility). The major-ion chemistry, deuterium, oxygen-18, and carbon isotopes of DIC were used in geochemical modeling (NETPATH) to determine groundwater sources, flow paths, mixing, and ages. The carbon isotopes of DOC were used to calculate groundwater ages that are independent of DIC model corrected carbon-14 ages. The DIC model corrected carbon-14 calculated ages were used to evaluate groundwater travel times for mixtures of water including water beneath Yucca Mountain. When possible, groundwater travel times were calculated for groundwater flow from beneath Yucca Mountain to down gradient sample sites. DOC carbon-14 groundwater ages were also calculated for groundwaters in the Yucca Mountain area. When possible, groundwater travel times were estimated for groundwater flow from beneath Yucca Mountain to down gradient groundwater sample sites using the DOC calculated groundwater ages. The DIC calculated groundwater ages were compared with DOC calculated groundwater ages ...
Date: June 25, 2007
Creator: Thomas, James; Decker, David; Patterson, Gary; Peterman, Zell; Mihevc, Todd; Larsen, Jessica et al.
Partner: UNT Libraries Government Documents Department

Amorphous Alloy Membranes Prepared by Melt-Spin methods for Long-Term use in Hydrogen Separation Applications

Description: Amorphous Ni-based alloy membranes show great promise as inexpensive, hydrogenselective membrane materials. In this study, we developed membranes based on nonprecious Ni-Nb-Zr alloys by adjusting the alloying content and using additives. Several studies on crystallization of the amorphous ribbons, in-situ x-ray diffraction, SEM and TEM, hydrogen permeation, hydrogen solubility, hydrogen deuterium exchange, and electrochemical studies were conducted. An important part of the study was to completely eliminate Palladium coatings of the NiNbZr alloys by hydrogen heattreatment. The amorphous alloy (Ni0.6Nb0.4)80Zr20 membrane appears to be the best with high hydrogen permeability and good thermal stability.
Date: February 28, 2013
Creator: Chandra, Dhanesh; Kim, Sang-Mun; Adibhatla, Anasuya; Dolan, Michael; Paglieri, Steve; Flanagan, Ted et al.
Partner: UNT Libraries Government Documents Department