1,043 Matching Results

Results open in a new window/tab. Unexpected Results? Search the Catalog Instead.

Occupational Radiation Exposure at Commercial Nuclear Power Reactors and Other Facilities 2008 (open access)

Occupational Radiation Exposure at Commercial Nuclear Power Reactors and Other Facilities 2008

This report summarizes the occupational exposure data that are maintained in the U.S. Nuclear Regulatory Commission (NRC) Radiation Exposure Information and Reporting System (REIRS). The bulk of the information contained in the report was compiled from the 2008 annual reports submitted by five of the seven categories1 of NRC licensees subject to the reporting requirements of 10 CFR 20.2206. The annual reports submitted by these licensees consist of radiation exposure records for each monitored individual. These records are analyzed for trends and presented in this report in terms of collective dose and the distribution of dose among the monitored individuals. Because there are no geologic repositories for high-level waste currently licensed and no low-level waste disposal facilities in operation, only five categories will be considered in this report.
Date: December 1, 2009
Creator: U.S. Nuclear Regulatory Commission, Office of Nuclear Regulatory Research
Object Type: Report
System: The UNT Digital Library
Evaluation of the Biological Effects of the Northwest Power Conservation Council's Mainstem Amendment on the Fisheries Upstream and Downstream of Libby Dam, Montana, 2007-2008 Annual Report. (open access)

Evaluation of the Biological Effects of the Northwest Power Conservation Council's Mainstem Amendment on the Fisheries Upstream and Downstream of Libby Dam, Montana, 2007-2008 Annual Report.

A new project began in 2005 to monitor the biological and physical effects of improved operations of Hungry Horse and Libby Dams, Montana, called for by the Northwest Power and Conservation Council (NPCC) Mainstem Amendment. This operating strategy was designed to benefit resident fish impacted by hydropower and flood control operations. Under the new operating guidelines, July through September reservoir drafts will be limited to 10 feet from full pool during the highest 80% of water supply years and 20 feet from full pool during the lowest 20% of water supply (drought) years. Limits were also established on how rapidly discharge from the dams can be increased or decreased depending on the season. The NPCC also directed the federal agencies that operate Libby and Hungry Horse Dams to implement a new flood control strategy (VARQ) and directed Montana Fish, Wildlife & Parks to evaluate biological responses to this operating strategy. The Mainstem Amendment operating strategy has not been fully implemented at the Montana dams as of June 2008 but the strategy will be implemented in 2009. This report highlights the monitoring methods used to monitor the effects of the Mainstem Amendment operations on fishes, habitat, and aquatic invertebrates upstream and …
Date: April 3, 2009
Creator: Sylvester, Ryan; Stephens, Brian & Tohtz, Joel
Object Type: Report
System: The UNT Digital Library
The impact of climate and flooding on tree ring growth of Fraxinus pennsylvanica in north-central Texas. (open access)

The impact of climate and flooding on tree ring growth of Fraxinus pennsylvanica in north-central Texas.

Tree cores of Fraxinus pennsylvanica were used in a dendrochronological analysis investigating the species' responses to climate and flooding. The objective was to develop a model that incorporates the effects of precipitation, temperature, and flooding on radial growth in this species in north-central Texas. The trees exhibited strong climatic signals. The study clearly shows that all three factors have significant impacts on tree ring growth both prior to and during growth; however, the nature and extent of these impacts are highly dependent on what time of year they occur. The large temporal variations in growth responses emphasize the importance of considering the timing of environmental events when studying tree growth responses.
Date: December 2009
Creator: Komperod, Mari
Object Type: Thesis or Dissertation
System: The UNT Digital Library
Annual Energy Outlook 2009: with Projections to 2030 (open access)

Annual Energy Outlook 2009: with Projections to 2030

The Annual Energy Outlook 2009 (AEO2009), prepared by the Energy Information Administration (EIA), presents long-term projections of energy supply, demand, and prices through 2030, based on results from EIA’s National Energy Modeling System (NEMS). EIA published an “early release” version of the AEO2009 reference case in December 2008.
Date: March 2009
Creator: United States. Energy Information Administration.
Object Type: Report
System: The UNT Digital Library
Hellsgate Big Game Winter Range Wildlife Mitigation Project: Annual Report 2008. (open access)

Hellsgate Big Game Winter Range Wildlife Mitigation Project: Annual Report 2008.

The Hellsgate Big Game Winter Range Wildlife Mitigation Project (Hellsgate Project) was proposed by the Confederated Tribes of the Colville Reservation (CTCR) as partial mitigation for hydropower's share of the wildlife losses resulting from Chief Joseph and Grand Coulee Dams. At present, the Hellsgate Project protects and manages 57,418 acres (approximately 90 miles2) for the biological requirements of managed wildlife species; most are located on or near the Columbia River (Lake Rufus Woods and Lake Roosevelt) and surrounded by Tribal land. To date we have acquired about 34,597 habitat units (HUs) towards a total 35,819 HUs lost from original inundation due to hydropower development. In addition to the remaining 1,237 HUs left unmitigated, 600 HUs from the Washington Department of Fish and Wildlife that were traded to the Colville Tribes and 10 secure nesting islands are also yet to be mitigated. This annual report for 2008 describes the management activities of the Hellsgate Big Game Winter Range Wildlife Mitigation Project (Hellsgate Project) during the past year.
Date: January 1, 2009
Creator: Whitney, Richard P.; Berger, Matthew T.; Rushing, Samuel & Peone, Cory
Object Type: Report
System: The UNT Digital Library
Fisheries Ecosystem Model of the Chesapeake Bay: Methodology, Parameterization, and Model Exploration (open access)

Fisheries Ecosystem Model of the Chesapeake Bay: Methodology, Parameterization, and Model Exploration

Report on the construction of a model to manage fisheries in the Chesapeake Bay region, to see how stocks affect the food web and provide quantified estimations. "This report describes an ecosystem model of the Chesapeake Bay, the Chesapeake Bay Fisheries Ecosystem Model (CBFEM), prepared using the Ecopath with Ecosim approach and software" (p. 5).
Date: October 2009
Creator: Christensen, Villy; Beattie, Alasdair; Buchanan, Claire; Ma, Hongguang; Martell, Steven J. D.; Latour, Robert J. et al.
Object Type: Report
System: The UNT Digital Library
Transuranic Contamination in Sediment and Groundwater at the U.S. DOE Hanford Site (open access)

Transuranic Contamination in Sediment and Groundwater at the U.S. DOE Hanford Site

A review of transuranic radionuclide contamination in sediments and groundwater at the DOE’s Hanford Site was conducted. The review focused primarily on plutonium-239/240 and americium-241; however, other transuranic nuclides were discussed as well, including neptunium-237, plutonium-238, and plutonium-241. The scope of the review included liquid process wastes intentionally disposed to constructed waste disposal facilities such as trenches and cribs, burial grounds, and unplanned releases to the ground surface. The review did not include liquid wastes disposed to tanks or solid wastes disposed to burial grounds. It is estimated that over 11,800 Ci of plutonium-239, 28,700 Ci of americium-241, and 55 Ci of neptunium-237 have been disposed as liquid waste to the near surface environment at the Hanford Site. Despite the very large quantities of transuranic contaminants disposed to the vadose zone at Hanford, only minuscule amounts have entered the groundwater. Currently, no wells onsite exceed the DOE derived concentration guide for plutonium-239/240 (30 pCi/L) or any other transuranic contaminant in filtered samples. The DOE derived concentration guide was exceeded by a small fraction in unfiltered samples from one well (299-E28-23) in recent years (35.4 and 40.4 pCi/L in FY 2006). The primary reason that disposal of these large quantities of …
Date: August 20, 2009
Creator: Cantrell, Kirk J.
Object Type: Report
System: The UNT Digital Library
Effect of coarse woody debris manipulation on soricid and herpetofaunal communities in upland pine stands of the southeastern coastal plain. (open access)

Effect of coarse woody debris manipulation on soricid and herpetofaunal communities in upland pine stands of the southeastern coastal plain.

Abstract -The majority of studies investigating the importance of coarse woody debris (CWD) to forest- floor vertebrates have taken place in the Pacific Northwest and southern Appalachian Mountains, while comparative studies in the southeastern Coastal Plain are lacking. My study was a continuation of a long-term project investigating the importance of CWD as a habitat component for shrew and herpetofaunal communities within managed pine stands in the southeastern Coastal Plain. Results suggest that addition of CWD can increase abundance of southeastern and southern short-tailed shrews. However, downed wood does not appear to be a critical habitat component for amphibians and reptiles. Rising petroleum costs and advances in wood utilization technology have resulted in an emerging biofuels market with potential to decrease CWD volumes left in forests following timber harvests. Therefore, forest managers must understand the value of CWD as an ecosystem component to maintain economically productive forests while conserving biological diversity.
Date: April 1, 2009
Creator: Davis, Justin, Charles
Object Type: Text
System: The UNT Digital Library
PEAT ACCRETION HISTORIES DURING THE PAST 6000 YEARS IN MARSHES OF THE SACRAMENTO - SAN JOAQUIN DELTA, CALIFORNIA, USA (open access)

PEAT ACCRETION HISTORIES DURING THE PAST 6000 YEARS IN MARSHES OF THE SACRAMENTO - SAN JOAQUIN DELTA, CALIFORNIA, USA

Peat cores were collected in 4 remnant marsh islands and 4 drained, farmed islands throughout the Sacramento - San Joaquin Delta of California in order to characterize the peat accretion history of this region. Radiocarbon age determination of marsh macrofossils at both marsh and farmed islands showed that marshes in the central and western Delta started forming between 6030 and 6790 cal yr BP. Age-depth models for three marshes were constructed using cubic smooth spline regression models. The resulting spline fit models were used to estimate peat accretion histories for the marshes. Estimated accretion rates range from 0.03 to 0.49 cm yr{sup -1} for the marsh sites. The highest accretion rates are at Browns Island, a marsh at the confluence of the Sacramento and San Joaquin rivers. Porosity was examined in the peat core from Franks Wetland, one of the remnant marsh sites. Porosity was greater than 90% and changed little with depth indicating that autocompaction was not an important process in the peat column. The mean contribution of organic matter to soil volume at the marsh sites ranges from 6.15 to 9.25% with little variability. In contrast, the mean contribution of inorganic matter to soil volume ranges from 1.40 …
Date: July 20, 2009
Creator: Drexler, J Z; de Fontaine, C S & Brown, T A
Object Type: Article
System: The UNT Digital Library
Historical Evaluation of Film Badge Dosimetry Y-12 Plant: Part 2–Neutron Radiation ORAUT-OTIB-0045 (open access)

Historical Evaluation of Film Badge Dosimetry Y-12 Plant: Part 2–Neutron Radiation ORAUT-OTIB-0045

A summary of the major neutron sources involved in radiation exposures to Y-12 workers is presented in this TIB. Graphical methods are used to evaluate available neutron dose data from quarterly exposures to Y-12 workers and to determine how the data could be used to derive neutron-to-gamma dose ratios for dose reconstruction purposes. This TIB provides estimates of neutron-to-gamma dose ratios for specific departments and a default value for the neutron-to-gamma dose ratio based on the pooled neutron dose data for all Y-12 departments.
Date: December 14, 2009
Creator: Kerr, G. D.; Frome, E. L.; Watkins, J. P. & Tankersley, W. G.
Object Type: Report
System: The UNT Digital Library
Understanding and preventing police use of excessive force: An analysis of attitudes toward police job satisfaction and human rights laws. (open access)

Understanding and preventing police use of excessive force: An analysis of attitudes toward police job satisfaction and human rights laws.

Although governments try to create strict policies and regulations to prevent abuses, use of excessive force is still a problem for almost every country including Turkey. This study is intended to help Turkish National Police administrators to understand and prevent police use of excessive force. Studies on police brutality categorize three factors that explain why police officers use excessive force; these are individual, situational and organizational. In addition to brutality theories, job satisfaction literature is examined in this study to understand the use of excessive force. Job satisfaction is found to be related with burnout, turnover, stress, commitment, and performance. The impact of officers' attitude toward the criminal justice system and/or laws has not been tested widely. Police officers attitudes toward human rights laws are examined in this study to measure its impact on attitude toward use of excessive force. A secondary data collected in Turkey are analyzed by structural equation modeling which provides confirmatory factor analysis, path analysis, and causal relationships between variables. It is found that police officers' attitude toward human rights laws is a significant predictor of their attitudes toward use of excessive force. Job satisfaction and education level are the other significant variables affecting attitude toward …
Date: December 2009
Creator: Akdogan, Huseyin
Object Type: Thesis or Dissertation
System: The UNT Digital Library
Post-Hurricane Assessment of Sensitive Habitats of the Flower Garden Banks Vicinity (open access)

Post-Hurricane Assessment of Sensitive Habitats of the Flower Garden Banks Vicinity

This report evaluates the damage cause by Hurricane Rita to the benthic habitats of four banks: Sonnier, McGrail, Geyer, and Bright. They measured the damage to bank caps the community structure, and used SCUBA to video record the evidence.
Date: July 2009
Creator: Robbart, Martha L.; Aronson, Richard B.; Deslarzes, Kenneth J. P.; Precht, William F.; Duncan, Leslie; Zimmer, Beth et al.
Object Type: Report
System: The UNT Digital Library
Tsunami disaster response: A case analysis of the information society in Thailand. (open access)

Tsunami disaster response: A case analysis of the information society in Thailand.

The December 2004 Indian Ocean Tsunami wrecked thousands of lives, homes, and livelihoods - losses that could have been avoided with timely and better information. A resource such as information is needed at a fundamental level much like water, food, medicine, or shelter. This dissertation examines the development of the Thai information society, in terms of the share of information workforce and the level of diffusion of information and communication technologies (ICT), as well as, the role of the Thai information society in response to the tsunami disaster. The study combined the historical and political economy analyses in explaining factors influencing the growth of information workforce and the development of ICT in Thailand. Interviews conducted in 2007-08 revealed the Thai information society responded to the 2004 Tsunami - the first global internet-mediated natural disaster - in two areas: on-site assistance in collecting and recording identification information of tsunami disaster victims and on-line dissemination of disaster relief information. The effectiveness of ICT institutions in providing the tsunami disaster relief efforts and increasing the development of the information society were assessed using statistical procedures analyzing the perceptions of the Internet-based survey respondents. The disaster effects on survey respondents were also assessed. The …
Date: December 2009
Creator: Aswalap, Supaluk Joy
Object Type: Thesis or Dissertation
System: The UNT Digital Library
Conceptual and computational basis for the quantification of margins and uncertainty. (open access)

Conceptual and computational basis for the quantification of margins and uncertainty.

In 2001, the National Nuclear Security Administration of the U.S. Department of Energy in conjunction with the national security laboratories (i.e, Los Alamos National Laboratory, Lawrence Livermore National Laboratory and Sandia National Laboratories) initiated development of a process designated Quantification of Margins and Uncertainty (QMU) for the use of risk assessment methodologies in the certification of the reliability and safety of the nation's nuclear weapons stockpile. This presentation discusses and illustrates the conceptual and computational basis of QMU in analyses that use computational models to predict the behavior of complex systems. Topics considered include (1) the role of aleatory and epistemic uncertainty in QMU, (2) the representation of uncertainty with probability, (3) the probabilistic representation of uncertainty in QMU analyses involving only epistemic uncertainty, (4) the probabilistic representation of uncertainty in QMU analyses involving aleatory and epistemic uncertainty, (5) procedures for sampling-based uncertainty and sensitivity analysis, (6) the representation of uncertainty with alternatives to probability such as interval analysis, possibility theory and evidence theory, (7) the representation of uncertainty with alternatives to probability in QMU analyses involving only epistemic uncertainty, and (8) the representation of uncertainty with alternatives to probability in QMU analyses involving aleatory and epistemic uncertainty. Concepts and …
Date: June 1, 2009
Creator: Helton, Jon Craig (Arizona State University, Tempe, AZ)
Object Type: Report
System: The UNT Digital Library
Water Quality in the Carrizo-Wilcox Aquifer, 1990-2006 (open access)

Water Quality in the Carrizo-Wilcox Aquifer, 1990-2006

Report providing data from a study on the water quality of the Carrizo-Wilcox Aquifer, one of the most prolific groundwater sources in Texas.
Date: January 2009
Creator: Texas Water Development Board
Object Type: Report
System: The Portal to Texas History
Fourth National Report on Human Exposure to Environmental Chemicals (open access)

Fourth National Report on Human Exposure to Environmental Chemicals

This report provides an ongoing assessment of the exposure of the U.S. population to environmental chemicals by the use of biomonitoring.
Date: 2009
Creator: unknown
Object Type: Text
System: The UNT Digital Library
Methods and Models of the Hanford Internal Dosimetry Program, PNNL-MA-860 (open access)

Methods and Models of the Hanford Internal Dosimetry Program, PNNL-MA-860

The Hanford Internal Dosimetry Program (HIDP) provides internal dosimetry support services for operations at the Hanford Site. The HIDP is staffed and managed by the Radiation and Health Technology group, within the Pacific Northwest National Laboratory (PNNL). Operations supported by the HIDP include research and development, the decontamination and decommissioning of facilities formerly used to produce and purify plutonium, and waste management activities. Radioelements of particular interest are plutonium, uranium, americium, tritium, and the fission and activation product radionuclides 137Cs, 90Sr, and 60Co. This manual describes the technical basis for the design of the routine bioassay monitoring program and for assessment of internal dose. The purposes of the manual are as follows: • Provide assurance that the HIDP derives from a sound technical base. • Promote the consistency and continuity of routine program activities. • Provide a historical record. • Serve as a technical reference for radiation protection personnel. • Aid in identifying and planning for future needs.
Date: September 30, 2009
Creator: Carbaugh, Eugene H.; Bihl, Donald E.; Maclellan, Jay A.; Antonio, Cheryl L. & Hill, Robin L.
Object Type: Report
System: The UNT Digital Library
Results of Self-Absorption Study on the Versapor 3000 Filters for Radioactive Particulate Air Sampling (open access)

Results of Self-Absorption Study on the Versapor 3000 Filters for Radioactive Particulate Air Sampling

Since the mid-1980s, Pacific Northwest National Laboratory (PNNL) has used a value of 0.85 as the correction factor for self absorption of activity for particulate radioactive air samples collected from building exhaust for environmental monitoring. This value accounts for activity that cannot be detected by direct counting of alpha and beta particles. Emissions can be degraded or blocked by filter fibers for particles buried in the filter material or by inactive dust particles collected with the radioactive particles. These filters are used for monitoring air emissions from PNNL stacks for radioactive particles. This paper describes an effort to re-evaluate self-absorption effects in particulate radioactive air sample filters (Versapor® 3000, 47 mm diameter) used at PNNL. There were two methods used to characterize the samples. Sixty samples were selected from the archive for acid digestion to compare the radioactivity measured by direct gas-flow proportional counting of filters to the results obtained after acid digestion of the filter and counting again by gas-flow proportional detection. Thirty different sample filters were selected for visible light microscopy to evaluate filter loading and particulate characteristics. Mass-loading effects were also considered. Filter ratios were calculated by dividing the initial counts by the post-digestion counts with the …
Date: February 17, 2009
Creator: Barnett, J. M.; Cullinan, Valerie I.; Barnett, Debra S.; Trang-Le, Truc LT; Bliss, Mary; Greenwood, Lawrence R. et al.
Object Type: Report
System: The UNT Digital Library
Biomass Energy Data Book (open access)

Biomass Energy Data Book

The Biomass Energy Data Book is a statistical compendium prepared and published by Oak Ridge National Laboratory (ORNL) under contract with the Biomass Program in the Energy Efficiency and Renewable Energy (EERE) program of the Department of Energy (DOE). Designed for use as a convenient reference, the book represents an assembly and display of statistics and information that characterize the biomass industry, from the production of biomass feedstocks to their end use, including discussions on sustainability. This is the second edition of the Biomass Energy Data Book which is only available online in electronic format. There are five main sections to this book. The first section is an introduction which provides an overview of biomass resources and consumption. Following the introduction to biomass, is a section on biofuels which covers ethanol, biodiesel and bio-oil. The biopower section focuses on the use of biomass for electrical power generation and heating. The fourth section is on the developing area of biorefineries, and the fifth section covers feedstocks that are produced and used in the biomass industry. The sources used represent the latest available data. There are also four appendices which include frequently needed conversion factors, a table of selected biomass feedstock characteristics, …
Date: January 2009
Creator: Wright, Lynn L.; Boundy, Robert Gary; Badger, Philip C; Perlack, Robert D & Davis, Stacy Cagle
Object Type: Report
System: The UNT Digital Library
Transportation Energy Data Book: Edition 28 (open access)

Transportation Energy Data Book: Edition 28

The Transportation Energy Data Book: Edition 28 is a statistical compendium prepared and published by Oak Ridge National Laboratory (ORNL) under contract with U.S Department of Energy, Office of Energy Efficiency and Renewable Energy, Vehicle Technologies Program and the Hydrogen, Fuel Cells, and Infrastructure Technologies Program. Designed for use as a desk-top reference, the data book represents an assembly and display of statistics and information that characterize transportation activity, and presents data on other factors that influence transportation energy use. The purpose of this document is to present relevant statistical data in the form of tables and graphs. The latest edition of the Data Book are available to a larger audience via the Internet (cta.ornl.gov/data). This edition of the Data Book has 12 chapters which focus on various aspects of the transportation industry. Chapter 1 focuses on petroleum; Chapter 2 energy; Chapter 3 highway vehicles; Chapter 4 light vehicles; Chapter 5 heavy vehicles; Chapter 6 alternative fuel vehicles; Chapter 7 fleet vehicles; Chapter 8 household vehicles; and Chapter 9 nonhighway modes; Chapter 10 transportation and the economy; Chapter 11 greenhouse gas emissions; and Chapter 12 criteria pollutant emissions. The sources used represent the latest available data. There are also three …
Date: June 1, 2009
Creator: Davis, Stacy Cagle; Diegel, Susan W & Boundy, Robert Gary
Object Type: Report
System: The UNT Digital Library
Upper Limits on the Number of Small Bodies in Sedna-Like Orbits by the TAOS Project (open access)

Upper Limits on the Number of Small Bodies in Sedna-Like Orbits by the TAOS Project

We present the results of a search for occultation events by objects at distances between 100 and 1000 AU in lightcurves from the Taiwanese-American Occultation Survey (TAOS). We searched for consecutive, shallow flux reductions in the stellar lightcurves obtained by our survey between 7 February 2005 and 31 December 2006 with a total of {approx} 4.5 x 10{sup 9} three-telescope simultaneous photometric measurements. No events were detected, allowing us to set upper limits on the number density as a function of size and distance of objects in Sedna-like orbits, using simple models.
Date: November 13, 2009
Creator: Wang, J.; Lehner, M. J.; Zhang, Z.; Bianco, F. B.; Alcock, C.; Chen, W. et al.
Object Type: Article
System: The UNT Digital Library
Deposition Velocities of Newtonian and Non-Newtonian Slurries in Pipelines (open access)

Deposition Velocities of Newtonian and Non-Newtonian Slurries in Pipelines

The WTP pipe plugging issue, as stated by the External Flowsheet Review Team (EFRT) Executive Summary, is as follows: “Piping that transports slurries will plug unless it is properly designed to minimize this risk. This design approach has not been followed consistently, which will lead to frequent shutdowns due to line plugging.” A strategy was employed to perform critical-velocity tests on several physical simulants. Critical velocity is defined as the point where a stationary bed of particles deposits on the bottom of a straight horizontal pipe during slurry transport operations. Results from the critical velocity testing provide an indication of slurry stability as a function of fluid rheological properties and transport conditions. The experimental results are compared to the WTP design guide on slurry transport velocity in an effort to confirm minimum waste velocity and flushing velocity requirements as established by calculations and critical line velocity correlations in the design guide. The major findings of this testing is discussed below. Experimental results indicate that the use of the Oroskar and Turian (1980) correlation in the design guide is conservative—Slurry viscosity has a greater affect on particles with a large surface area to mass ratio. The increased viscous forces on these …
Date: March 25, 2009
Creator: Poloski, Adam P.; Adkins, Harold E.; Abrefah, John; Casella, Andrew M.; Hohimer, Ryan E.; Nigl, Franz et al.
Object Type: Report
System: The UNT Digital Library
Observed 1970-2005 cooling of summer daytime temperatures in coastal California (open access)

Observed 1970-2005 cooling of summer daytime temperatures in coastal California

The study evaluated 1948-2004 summer (JJA) mean monthly air temperatures for two California air basins: SoCAB and SFBA. The study focuses on the more rapid post-1970 warming period, and its daily T{sub min} and T{sub max} values were used to produce average monthly values and spatial distributions of trends for each air basins. Additional analyses included T{sub D} values at two NWS sites, SSTs, NCEP reanalysis sea-level pressures, and GCM T{sub ave}-values. Results for all California COOP sites together showed increased JJA T{sub ave}-values; asymmetric warming, as T{sub min}-values increase faster than T{sub max}-values; and thus decreased DTR values. The spatial distribution of observed SoCAB and SFBA T{sub max} values exhibited a complex pattern, with cooling in low-elevation coastal-areas open to marine air penetration and warming at inland areas. Results also showed that decreased DTR values in the valleys arose from small increases at 'inland' sites combined with large decreases at 'coastal' sites. Previous studies suggest that cooling JJA T{sub max}-values in coastal California were due to increased irrigation, coastal upwelling, or cloud cover, while the current hypothesis is that they arises from GHG-induced global-warming of 'inland' areas, which results in increased sea breeze flow activity. Sea level pressure trends …
Date: May 15, 2009
Creator: Lebassi, B.; Gonzalez, J.; Fabris, D.; Maurer, E.; Miller, N.; Milesi, C. et al.
Object Type: Article
System: The UNT Digital Library
Calibration of a Neutron Hydroprobe for Moisture Measurements in Small-Diameter Steel-Cased Boreholes (open access)

Calibration of a Neutron Hydroprobe for Moisture Measurements in Small-Diameter Steel-Cased Boreholes

Computation of soil moisture content from thermalized neutron counts for the T-Farm Interim cover requires a calibration relationship but none exists for 2-in tubes. A number of calibration options are available for the neutron probe, including vendor calibration, field calibration, but none of these methods were deemed appropriate for the configuration of interest. The objective of this work was to develop a calibration relation for converting neutron counts measured in 2-in access tubes to soil water content. The calibration method chosen for this study was a computational approach using the Monte Carlo N-Particle Transport Code (MCNP). Model calibration was performed using field measurements in the Hanford calibration models with 6-in access tubes, in air and in the probe shield. The bet-fit model relating known water content to measured neutron counts was an exponential model that was essentially equivalent to that currently being used for 6-in steel cased wells. The MCNP simulations successfully predicted the neutron count rate for the neutron shield and the three calibration models for which data were collected in the field. However, predictions for air were about 65% lower than the measured counts . This discrepancy can be attributed to uncertainties in the configuration used for the …
Date: August 1, 2009
Creator: Ward, Anderson L. & Wittman, Richard S.
Object Type: Report
System: The UNT Digital Library