Partner
UNT Libraries Government Documents Department
283
UNT Libraries Special Collections
48
Oklahoma Historical Society
42
UNT Libraries
15
Sterling Municipal Library
10
National Museum of the Pacific War/Admiral Nimitz Foundation
8
Carl Albert Congressional Research and Studies Center
5
San Antonio Public Library
5
Patrick Heath Public Library
4
Nellie Pederson Civic Library
3
47 More
Collection
Office of Scientific & Technical Information Technical Reports
141
Texas Digital Newspaper Program
97
Congressional Research Service Reports
89
Oklahoma Digital Newspaper Program
47
Tocker Foundation Grant
46
Government Accountability Office Reports
45
Texas Daily Newspaper Association
37
The Greensheet
11
The Baytown Sun
10
Chickasha Newspaper Collection
9
86 More
Country
States
Decade
Month
Day
Language
492 Matching Results
Results open in a new window/tab.
prev
Results:
481 - 492 of
492
The Plutonium Transition from Nuclear Weapons to Crypt
With the end of the ''Cold War'' thousands of nuclear warheads are being dismantled. The National Academy of Sciences termed this growing stockpile of plutonium and highly enriched uranium ''a clear and present danger'' to international security. DOE/MD selected a duel approach to plutonium disposition--burning MOX fuel in existing reactors and immobilization in a ceramic matrix surrounded by HLW glass. MOX material will be pits and clean metal. The challenges come with materials that will be transferred to Immobilization--these range from engineered materials to residues containing < 30% Pu. Impurity knowledge range from guesses to actual data. During packaging, sites will flag ''out of the ordinary'' containers for characterized. If the process history is lost, characterization cost will escalate rapidly. After two step blending and ceramic precursor addition, cold press and sintering will form 0.5-kg ceramic pucks containing {le}50 g Pu. Pucks will be sealed in cans, placed into magazines, then into HLW canisters; these canisters will be filled with HLW glass prior to being transported to the HLW repository. The Immobilization Program must interface with DP, EM, RW, and NN. Overlaid on top of these interfaces are the negotiations with the Russians.
Date:
March 14, 2000
Creator:
Gray, L.W.
Object Type:
Article
System:
The UNT Digital Library
The Potential Impacts on Aquatic Ecosystems from the Release of Trace Elements in Geothermal Fluids
Geothermal energy will likely constitute an increasing percentage of our nation's future energy ''mix,'' both for electrical and nonelectrical uses. Associated with the exploitation of geothermal resources is the handling and disposal of fluids which contain a wide variety of potentially toxic trace elements. We present analyses of 14 trace elements found in hydrothermal fluids from various geothermal reservoirs in the western United States. The concentrations of these elements vary over orders of magnitude between reservoirs. Potential impacts are conservatively assessed on the basis of (1) toxicity to freshwater biota, and (2) bioaccumulation in food fish to the point where consumption might be hazardous to human health. Trace element concentrations generally range from benign levels to levels which might prove toxic to freshwater biota and contaminate food fisheries. We stress the need for site-specific analyses and careful handling of geothermal fluids in order to minimize potential impacts.
Date:
March 14, 2000
Creator:
Cushman, R.M.
Object Type:
Report
System:
The UNT Digital Library
Rains County Leader (Emory, Tex.), Vol. 112, No. 39, Ed. 1 Tuesday, March 14, 2000
Weekly newspaper from Emory, Texas that includes local, state, and national news along with advertising.
Date:
March 14, 2000
Creator:
Hill, Earl Clyde, Jr.
Object Type:
Newspaper
System:
The Portal to Texas History
Remedial investigation report for J-Field, Aberdeen Proving Ground, Maryland. Volume 1: Remedial investigation results
This report presents the results of the remedial investigation (RI) conducted at J-Field in the Edgewood Area of Aberdeen Proving Ground (APG), a U.S. Army installation located in Harford County, Maryland. Since 1917, activities in the Edgewood Area have included the development, manufacture, and testing of chemical agents and munitions and the subsequent destruction of these materials at J-Field by open burning and open detonation. These activities have raised concerns about environmental contamination at J-Field. This RI was conducted by the Environmental Conservation and Restoration Division, Directorate of Safety, Health and Environmental Division of APG, pursuant to requirements outlined under the Comprehensive Environmental Response, Compensation, and Liability Act, as amended (CERCLA). The RI was accomplished according to the procedures developed by the U.S. Environmental Protection Agency (EPA 1988). The RI provides a comprehensive evaluation of the site conditions, nature of contaminants present, extent of contamination, potential release mechanisms and migration pathways, affected populations, and risks to human health and the environment. This information will be used as the basis for the design and implementation of remedial actions to be performed during the remedial action phase, which will follow the feasibility study (FS) for J-Field.
Date:
March 14, 2000
Creator:
Yuen, C. R.; Martino, L. E.; Biang, R. P.; Chang, Y. S.; Dolak, D.; Van Lonkhuyzen, R. A. et al.
Object Type:
Report
System:
The UNT Digital Library
The Rice Thresher (Houston, Tex.), Vol. 87, No. 20, Ed. 1 Tuesday, March 14, 2000
A weekly student newspaper from the Rice University in Houston, Texas that includes campus news and commentaries along with advertising.
Date:
March 14, 2000
Creator:
McAlister, Jett & Tam, Mariel
Object Type:
Newspaper
System:
The Portal to Texas History
Sapulpa Daily Herald (Sapulpa, Okla.), Vol. 84, No. 156, Ed. 1 Tuesday, March 14, 2000
Daily newspaper from Sapulpa, Oklahoma that includes local, state, and national news along with advertising.
Date:
March 14, 2000
Creator:
Quinnelly, Lorrie J.
Object Type:
Newspaper
System:
The Gateway to Oklahoma History
Sensitivity and uncertainty analysis of a polyurethane foam decomposition model
Sensitivity/uncertainty analyses are not commonly performed on complex, finite-element engineering models because the analyses are time consuming, CPU intensive, nontrivial exercises that can lead to deceptive results. To illustrate these ideas, an analytical sensitivity/uncertainty analysis is used to determine the standard deviation and the primary factors affecting the burn velocity of polyurethane foam exposed to firelike radiative boundary conditions. The complex, finite element model has 25 input parameters that include chemistry, polymer structure, and thermophysical properties. The response variable was selected as the steady-state burn velocity calculated as the derivative of the burn front location versus time. The standard deviation of the burn velocity was determined by taking numerical derivatives of the response variable with respect to each of the 25 input parameters. Since the response variable is also a derivative, the standard deviation is essentially determined from a second derivative that is extremely sensitive to numerical noise. To minimize the numerical noise, 50-micron elements and approximately 1-msec time steps were required to obtain stable uncertainty results. The primary effect variable was shown to be the emissivity of the foam.
Date:
March 14, 2000
Creator:
Hobbs, Michael L. & Robinson, David G.
Object Type:
Article
System:
The UNT Digital Library
Technical Integration of Defense Threat Reduction Agency (DTRA) Location Related Funded Projects into the DOE Knowledge Base
This document directly reviews the current Defense Threat Reduction Agency (DTRA) PRDA contracts and describes how they can best be integrated with the DOE CTBT R&D Knowledge Base. Contract descriptions and numbers listed below are based on the DOE CTBT R&D Web Site - http://www.ctbt.rnd.doe.gov. More detailed information on the nature of each contract can be found through this web site. In general, the location related PRDA contracts provide products over a set of categories. These categories can be divided into five areas, namely: Contextual map information; Reference event data; Velocity models; Phase detection/picking algorithms; and Location techniques.
Date:
March 14, 2000
Creator:
Schultz, C.A.; Bhattacharyya, J.; Flanaga, M.; Goldstein, P.; Myers, S. & Swenson, J.
Object Type:
Report
System:
The UNT Digital Library
TEM investigation of U{sup 6+} and Re{sup 7+} reduction by Desulfovibrio desulfuricans, a sulfate-reducing bacterium
Uranium and its fission product Tc in aerobic environment will be in the forms of UO{sub 2}{sup 2+} and TcO{sub 4}{sup {minus}}. Reduced forms of tetravalent U and Tc are sparingly soluble. As determined by transmission electron microscopy, the reduction of uranyl acetate by immobilized cells of Desulfovibrio desulfuricans results in the production of black uraninite nanocrystals precipitated outside the cell. Some nanocrystals are associated with outer membranes of the cell as revealed from cross sections of these metabolic active sulfate-reducing bacteria. The nanocrystals have an average diameter of 5 nm and have anhedral shape. The reduction of Re{sup 7+} by cells of Desulfovibrio desulfuricans is fast in media containing H{sub 2} an electron donor, and slow in media containing lactic acid. It is proposed that the cytochrome in these cells has an important role in the reduction of uranyl and Re{sup 7+} is (a chemical analogue for Tc{sup 7+}) through transferring an electron from molecular hydrogen or lactic acid to the oxyions of UO{sub 2}{sup 2+} and TcO{sub 4}{sup {minus}}.
Date:
March 14, 2000
Creator:
Xu, Huifang; Barton, Larry L.; Choudhury, Keka; Zhang, Pengchu & Wang, Yifeng
Object Type:
Article
System:
The UNT Digital Library
Thermodynamic stability of actinide pyrochlore minerals in deep geologic repository environments
Crystalline phases of pyrochlore (e.g., CaPuTi{sub 2}O{sub 7}, CaUTi{sub 2}O{sub 7}) have been proposed as a durable ceramic waste form for disposal of high level radioactive wastes including surplus weapons-usable plutonium. In this paper, the authors use a linear free energy relationship to predict the Gibbs free energies of formation of pyrochlore phases (CaMTi{sub 2}O{sub 7}). The Pu-pyrochlore phase is predicted to be stable with respect to PuO{sub 2}, CaTiO{sub 3}, and TiO{sub 2} at room temperatures. Pu-pyrochlore is expected to be stable in a geologic repository where silica and carbonate components are absent or limited. The authors suggest that a repository in a salt formation be an ideal environment for disposal of high level, pyrochlore-based ceramic wastes. In such environment, adding CaO as a backfill will make pyrochlore minerals thermodynamically stable and therefore effectively prevent actinide release from these mineral phases.
Date:
March 14, 2000
Creator:
Wang, Yifeng & Xu, Huifang
Object Type:
Article
System:
The UNT Digital Library
Ultrasonic Imaging for Poling Uniformity Measurements in PZT Ceramic Elements
This report summarizes the results of a project sponsored by Honeywell Corporation (formerly AlliedSignal Inc.) Federal Manufacturing and Technologies/Kansas City (FM and T/KC) and conducted jointly with the University of Missouri, Rolla, titled ''Ultrasonic Imaging for Poling Uniformity Measurements in PZT Ceramic Elements.'' In this three-month research project, a series of experiments was performed on soft and hard lead-zirconate-titanate (PZT) structures to determine the effectiveness of ultrasonic measurements as a nondestructive method of evaluating poling quality and uniformity. The study revealed that acoustic velocity correlates well with the degree of poling of PZT structures, as predicted by elastic theory. Additionally, time-of-flight (TOF) imaging was shown to be an ideal tool for viewing the spatial distribution of poled material and of material affected by the electric field beyond the edge of electroded regions. Finally, the effectiveness of ultrasonic methods for flaw detection and evaluation of PZT/stainless steel bonds was also demonstrated.
Date:
March 14, 2000
Creator:
Jamieson, E. E.
Object Type:
Report
System:
The UNT Digital Library
Variation of equivalence ratio and element ratios in low-pressure premixed flames of aliphatic fuels
In previously published work it was found that the element ratios (such as C/O, H/O, H/C) and the equivalence ratio all varied in the flame zone of a low-pressure premixed fuel-rich benzene/oxygen/argon laminar flat flame. These variations were seen from analyses of both the data and detailed kinetic modeling. In the present work, seven additional flames were analyzed in the same manner, including five flames with a single hydrocarbon fuel (methane, acetylene, ethylene, allene, and propene) and two flames with a mixture of fuels (acetylene/allene, hydrogen/allene). All the flames had argon as the diluent, with pressures between 20 and 37.5 Torr, equivalence ratios between 1.6 and 2.5, cold gas velocities between 42 and 126 cm/sec. All of these flames showed variations in the element ratios and equivalence ratios. Furthermore, these variations changed in a consistent pattern with respect to the molecular weight of the fuel. In the flame zone, the percent change in the H/O, C/O and equivalence ratios increased with increasing molecular weight of the fuel, except for the hydrogen/allene flame in which the C/O ratio first increases, then decreases in the flame zone. Also, unlike all the other hydrocarbon flames, the C/O ratio decreases below its inlet value …
Date:
March 14, 2000
Creator:
Pope, C. J. & Miller, J. A.
Object Type:
Article
System:
The UNT Digital Library