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460
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203
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112
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106
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67
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15,324 Matching Results
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Speciation of uranium after microbial action by XANES and XPS
The speciation of radionuclides and toxic metals in wastes subjected to microbial action is important in determining the extent of stabilization in a disposal environment. As part of an ongoing study, we investigated the reduction of uranium by a Clostridium sp. using X-ray absorption neat edge spectroscopy (XANES) at the National Synchrotron Light Source (NSLS) and X-ray photoelectron spectroscopy (XPS). XPS analysis of uranyl acetate containing hexavalent uranium exhibited a binding energy of 382.0eV at the U 4f{sub 7/2} peak. The sample incubated in the presence of bacteria was shifted to lower binding energy (380.6eV), confirming the reduction of U{sup 6+} to U{sub 4+} at the bacterial surface. XANES analysis, using an electron yield detector, was performed at the M{sub v} absorption edge (3d-->5f). The absorption peak energy of the sample exhibited a shift from 3551.1eV to 3550.1eV which is higher than uranium metal (3549.6eV ) but lower than U{sup 4+} (3550.4eV). This indicates the presence of U{sup 3+} which is probably located beneath the surface within the biomass. Anaerobic bacterial treatment of wastes containing uranyl ion can result in the stabilization of uranium.
Date:
December 31, 1993
Creator:
Dodge, C. J.; Francis, A. J.; Lu, F.; Halada, G. P.; Kagwade, S. V. & Clayton, C. R.
Object Type:
Article
System:
The UNT Digital Library
Species and community response to above normal precipitation following prolonged drought in the northern Mojave Desert
Little information is available on how desert plant communities that are dominated by perennial species respond to normal and above normal precipitation following prolonged drought. Intuitively, one would expect total canopy cover to increase. Whether a concomitant increase in the density of perennial species also occurs is unknown. Even less is known about how individual species respond to above normal precipitation following drought. From 1987 through 1991 a prolonged drought occurred in much of the western United States, including the northern Mojave Desert. In March 1991 the northern Mojave Desert received well above normal precipitation. The following two winters (December--March) also had above normal precipitation (150 to 200 % of normal, unpublished data). Ongoing vegetation characterization studies by the US Department of Energy (DOE) at Yucca Mountain, Nevada, allowed EG&G Energy Measurements to collect data that could be used to infer how both vegetation associations and individual species respond to above normal precipitation following prolonged drought. This paper reports the preliminary results.
Date:
December 31, 1993
Creator:
Schultz, B.W. & Ostler, W.K.
Object Type:
Article
System:
The UNT Digital Library
Species status of Mill Creek Elliptio
This report discusses environmental effects of the Savannah River Plant on aqautic populations in Mill Creek and surrounding tributaries. Of particular concern was the status of Elliptio. Genetics and phenotypic characteristics have shown that the current classification system is not adequate for these populations. The appendices characterize genetic variability at different loci, electrophoretic data, allele frequencies, sympatric species, and anatomical characters.
Date:
December 31, 1993
Creator:
Davis, G. M. & Mulvey, M.
Object Type:
Report
System:
The UNT Digital Library
Specifying the surface finish of x-ray mirrors
Our measurements of x-ray mirrors at Brookhaven indicate that the power spectral densities of their finish errors have inverse power-law or fractal forms, rather than being flat at low frequencies as is usually assumed. This paper reviews these data and discusses how this apparent divergent behavior leads to finite but unconventional effects in imaging. Results are then used to develop more rational and realistic surface-finish specifications.
Date:
December 31, 1993
Creator:
Church, E. L. & Takacs, P. Z.
Object Type:
Article
System:
The UNT Digital Library
Spectroscopic and Dynamical Studies of Highly Energized Small Polyatomic Molecules. Technical Progress Report, July 1, 1992--October 31, 1993
Stimulated emission pumping was used to determine molecular constants and linewidths of vibrational levels of HCO {tilde X}{sup 2}A{prime} state in an energy region. Some of the results of the initial study of the HCO {tilde B}{l_arrow}{tilde X} transition were the subject of ab initio calculations. A paper was written which provides a lineshape and linestrength theory for Frequency Modulation (FM) enhanced Magnetic Rotation Spectroscopy (free radical spectroscopy). Pulsed dye amplification does not degrade the sensitivity of FM spectroscopy; a pulsed amplified FM spectrometer is being set up. A superpolyad model is being tested and extended for acetylene states. An ICCD-DF (intensified change-coupled detector-dispersed fluorescence) scheme is being set up.
Date:
December 31, 1993
Creator:
Field, R. W. & Silbey, R. J.
Object Type:
Report
System:
The UNT Digital Library
Spectroscopic investigation of the vibrational quasi-continuum arising from internal rotation of a methyl group. Final report, 1990 - 1993
Spectroscopy was used to study the vibrational quasi-continuum arising from internal rotation of the methyl group in acetaldehyde. We now understand the torsion-rotation levels from all 3 torsional states below the top of the torsional barrier. Investigations of four ordinary vibrational states in acetaldehyde are in progress.
Date:
December 31, 1993
Creator:
Hougen, J. T.
Object Type:
Report
System:
The UNT Digital Library
Spin and precision electroweak physics
A perspective on fundamental parameters and precision tests of the Standard Model is given. Weak neutral current reactions are discussed with emphasis on those processes involving (polarized) electrons. The role of electroweak radiative corrections in determining the top quark mass and probing for ``new physics`` is described.
Date:
December 31, 1993
Creator:
Marciano, W. J.
Object Type:
Article
System:
The UNT Digital Library
Spinnability of silica sols: The role of alkoxy group exchange
The exchange and spinnability of several systems with the general form Si(OR){sub 4} (where R = CH{sub 3}, C{sub 2}H{sub 5}) in ethanol, propanol and butanol were investigated. We have followed the alkoxy group exchange, hydrolysis and condensation reactions, and Q distributions of these systems using {sup 29}Si and {sup 17}O NMR. Observed differences in spinnability of the various sol-gel systems are attributed to the effect of the bulkiness of the alkoxy group on its reactivity.
Date:
December 31, 1993
Creator:
Prabakar, S.; Assink, R. A. & Irwin, A. D.
Object Type:
Article
System:
The UNT Digital Library
Stability and precipitation kinetics in Si{sub 1{minus}y}C{sub y}/Si and Si{sub 1{minus}x{minus}y}Ge{sub x}C{sub y}/Si heterostructures prepared by solid phase epitaxy
This study investigates the stability of metastable Si{sub 1{minus}y}C{sub y}/Si heterostructures during rapid thermal annealing (RTA) over a temperature range of 1,000--1,150 C. Heterostructures of Si{sub 1{minus}y}C{sub y}/Si and Si{sub 1{minus}x{minus}y}Ge{sub x}C{sub y}/Si (x {equals} 0.77, Y {<=} .0014) were formed by solid phase epitaxy from C implanted, preamorphized substrates using a 30 minute 700 C anneal in N{sub 2}. The occupancy of C in substitution lattice sites was monitored by Fourier Transform Infrared Absorption spectroscopy. The layer strain was monitored by rocking curve X-ray diffraction and the structural changes in the layers were determined using plan-view and X-sectional transmission electron microscopy (TEM). For anneals of 1,150 C or above, all the substitutional C was lost from the Si lattice after 30 seconds. TEM verified that the strain relaxation was the result of C precipitating into highly aligned {beta}SiC particles rather than by the formation of extended defects. No nucleation barrier was observed for the loss of substitutional C. Preliminary results will also be discussed for Si{sub 1{minus}x{minus}y}Ge{sub x}C{sub y}/Si heterostructures where there is the additional factor of the competition between strain energy and the chemical driving forces.
Date:
December 31, 1993
Creator:
Strane, J. W.; Picraux, S. T.; Stein, H. J.; Lee, S. R.; Candelaria, J.; Theodore, D. et al.
Object Type:
Report
System:
The UNT Digital Library
Stabilization of spent sorbents from coal gasification. Final technical report, September 1, 1992--August 31, 1993
The objective of this investigation was to determine the rates of reactions involving partially sulfided dolomite and oxygen, which is needed for the design of the reactor system for the stabilization of sulfide-containing solid wastes from gasification of high sulfur coals. To achieve this objective, samples of partially sulfided dolomite were reacted with oxygen at a variety of operating conditions in a fluidized-bed reactor. The effect of external diffusion was eliminated by using small quantities of the sorbent and maintaining a high flow rate of the reactant gas. The reacted sorbents were analyzed to determine the extent of conversion as a function of operating variables including sorbent particle size, reaction temperature and pressure, and oxygen concentration. The results of sulfation tests indicate that the rate of reaction increases with increasing temperature, increasing oxygen partial pressure, and decreasing sorbent particle size. The rate of the sulfation reaction can be described by a diffuse interface model where both chemical reaction and intraparticle diffusion control the reaction rate. The kinetic model of the sulfation reaction was used to determine the requirements for the reactor system, i.e., reactor size and operating conditions, for successful stabilization of sulfide-containing solid wastes from gasification of high sulfur …
Date:
December 31, 1993
Creator:
Abbasian, J.; Hill, A. H.; Rue, D. M. & Wangerow, J. R.
Object Type:
Report
System:
The UNT Digital Library
A staged fluidized-bed comubstion and filter system
A staged fluidized-bed combustion and filter system for substantially reducing the quantity of waste through the complete combustion into ash-type solids and gaseous products. The device has two fluidized- bed portions, the first primarily as a combustor/pyrolyzer bed, and the second as a combustor/filter bed. The two portions each have internal baffles to define stages so that material moving therein as fluidized beds travel in an extended route through those stages. Fluidization and movement is achieved by the introduction of gasses into each stage through a directional nozzle. Gases produced in the combustor/pyrolyzer bed are permitted to travel into corresponding stages of the combustor/filter bed through screen filters that permit gas flow but inhibit solids flow. Any catalyst used in the combustor/filter bed is recycled. The two beds share a common wall to minimize total volume of the system. A slightly modified embodiment can be used for hot gas desulfurization and sorbent regeneration. Either side-by-side rectangular beds or concentric beds can be used. The system is particularly suited to the processing of radioactive and chemically hazardous waste.
Date:
December 31, 1993
Creator:
Mei, J.S. & Halow, J.S.
Object Type:
Patent
System:
The UNT Digital Library
STARS missile -- Modal analysis of first-flight data using the Natural Excitation Technique, NExT
The Natural Excitation Technique (NExT) was used to analyze STARS launch data during first and second stage flight using telemetered acceleration data. A continuous track of modal frequencies and modal damping was acquired for the first and second elastic modes of the system during first stage flight and for the first mode during second stage flight. The results from this modal analysis of launch data allowed a final quantification of the inherent bias errors which result from ground-based modal tests. Also, NExT is shown to be an important new tool for analyzing structural dynamics data during launch.
Date:
December 31, 1993
Creator:
James, G. H.; Carne, T. G. & Edmunds, R. S.
Object Type:
Report
System:
The UNT Digital Library
Startup status of the Replacement Tritium Facility at the Savannah River Site
Tritium processing operations have been performed at the Savannah River Site (SRS) since 1955. It was determined in the early 1980`s that new tritium facilities were required in order to meet increasingly stringent safety and environmental requirements while maintaining productivity. Construction of a new tritium handling facility, the Replacement Tritium Facility (RTF), began in 1987. This new facility incorporates the latest technology and design philosophy to mitigate accident consequences, enhance operational safety, minimize tritium losses to the environment, and ensure material safeguards and security. The RTF is currently completing startup operations. This report details key features addressed during the design and startup of this facility.
Date:
December 31, 1993
Creator:
Horen, A. S.; Motyka, T.; Montini, M. J. & Hashinger, R. F.
Object Type:
Article
System:
The UNT Digital Library
Static renewal tests using Anodonta imbecillis (freshwater mussels). Anodonta imbecillis copper sulfate reference toxicant/food test, Clinch River-Environmental Restoration Program (CR-ERP)
Reference toxicant testing using juvenile freshwater mussels was conducted as part of the CR-ERP biomonitoring study of Clinch River sediments to assess the sensitivity of test organisms and the overall performance of the test. Tests were conducted using moderately hard synthetic water spiked with known concentrations of copper as copper sulfate. Two different foods, phytoplankton and YCT-Selenastrum (YCT-S), were tested in side by side tests to compare food quality. Toxicity testing of copper sulfate reference toxicant was conducted from July 6--15, 1993. The organisms used for testing were juvenile fresh-water mussels (Anodonta imbecillis). Although significant reduction in growth, compared to the phytoplankton control, was seen in all treatments, including the YCT-S Control, the consequence of this observation has not been established. Ninety-day testing of juvenile mussels exhibited large variations in growth within treatment and replicate groups. Attachments to this report include: Toxicity test bench sheets and statistical analyses; and Copper analysis request and results.
Date:
December 31, 1993
Creator:
Simbeck, D.J.
Object Type:
Report
System:
The UNT Digital Library
Static renewal tests using Anodonta imbecillis (freshwater mussels). Anodonta imbecillis QA test 1, Clinch River-Environmental Restoration Program (CR-ERP)
Toxicity testing of split whole sediment samples using juvenile freshwater mussels (Anodonta imbecillis) was conducted by TVA and CR-ERP personnel as part of the CR-ERP biomonitoring study of Clinch River sediments to provide a quality assurance mechanism for test organism quality and overall performance of the test. In addition, testing included procedures comparing daily renewal versus non-renewal of test sediments. Testing of sediment samples collected July 15 from Poplar Creek Miles 6.0 and 5.1 was conducted from July 21--30, 1993. Results from this test showed no toxicity (survival effects) to fresh-water mussels during a 9-day exposure to the sediments. Side by side testing of sediments with daily sediment renewal and no sediment renewal showed no differences between methods. This may be due to the absence of toxicity in both samples and may not reflect true differences between the two methods for toxic sediment. Attachments to this report include: Chain of custody forms -- originals; Toxicity test bench sheets and statistical analyses; and Ammonia analysis request and results.
Date:
December 31, 1993
Creator:
Simbeck, D.J.
Object Type:
Report
System:
The UNT Digital Library
Static renewal tests using Anodonta imbecillis (freshwater mussels). Anodonta imbecillis QA test 2, Clinch River-Environmental Restoration Program (CR-ERP)
Toxicity testing of split whole sediment samples using juvenile freshwater mussels (Anodonta imbecillis) was conducted by TVA to provide a quality assurance mechanism for test organism quality and overall performance of the test being conducted by CR-ERP personnel as part of the CR-ERP biomonitoring study of Clinch River sediments. Testing of sediment samples collected August 14 from Poplar Creek Miles 6.0 and 4.3 was conducted from August 24--September 2, 1993. Results from this test showed no toxicity (survival effects) to fresh-water mussels during a 9-day exposure to the sediments. Attachments to this report include: Chain of custody form -- original; Toxicity test bench sheets and statistical analyses; and Ammonia analysis request and results.
Date:
December 31, 1993
Creator:
Simbeck, D.J.
Object Type:
Report
System:
The UNT Digital Library
Static renewal tests using Anodonta imbecillus (freshwater mussels). Anodonta imbecillis copper sulfate reference toxicant test, Clinch River-Environmental Restoration Program (CR-ERP)
Reference toxicant testing using juvenile freshwater mussels was conducted as part of the CR-ERP biomonitoring study of Clinch River sediments to assess the sensitivity of test organisms and the overall performance of the test. Tests were conducted using moderately hard synthetic water spiked with known concentrations of copper as copper sulfate. Toxicity testing of copper sulfate reference toxicant was conducted from May 12--21, 1993. The organisms used for testing were juvenile fresh-water mussels (Anodonta imbecillis). Results from this test showed an LC{sub 50} value of 1.12 mg Cu/L which is lower than the value of 2.02 mg Cu/L obtained in a previous test. Too few tests have been conducted with copper as the toxicant to determine a normal range of values. Attachments to this report include: Toxicity test bench sheets and statistical analyses; Copper analysis request and results; and Personnel training documentation.
Date:
December 31, 1993
Creator:
Simbeck, D.J.
Object Type:
Report
System:
The UNT Digital Library
Static renewal tests using Pimephales promelas (fathead minnows) and Ceriodaphnia dubia (daphnids). Clinch River-Environmental Restoration Program (CR-ERP) pilot study, ambient water toxicity
Clinch River-Environmental Restoration Program (CR-ERP) personnel and Tennessee Valley Authority (TVA) personnel conducted a pilot study during the week of April 22--29, 1993, prior to initiation of CR-ERP Phase 2 Sampling and Analysis activities. The organisms specified for testing were larval fathead minnows, Pimephales promelas, and the daphnid, Ceriodaphnia dubia. Surface water samples were collected by TVA Field Engineering personnel from Clinch River Mile 9.0 and Poplar Creek Kilometer 1.6 on April 21, 23, and 26. Samples were split and provided to the CR-ERP and TVA toxicology laboratories for testing. Exposure of test organisms to these samples resulted in no toxicity (survival, growth, or reproduction) to either species in testing conducted by TVA. Attachments to this report include: Chain of custody forms -- originals; Toxicity test bench sheets and statistical analyses; Reference toxicant test information; and Personnel training documentation.
Date:
December 31, 1993
Creator:
Simbeck, D.J.
Object Type:
Report
System:
The UNT Digital Library
Static renewal tests using Pimephales promelas (fathead minnows) and Ceriodaphnia dubia (daphnids). Clinch River-Environmental Restoration Program (CR-ERP) study, ambient water toxicity
Clinch River-Environmental Restoration Program (CR-ERP) personnel and Tennessee Valley Authority (TVA) personnel conducted a study during the week of July 22--29, 1993. The organisms specified for testing were larval fathead minnows, Pimephales promelas, and the daphnid, Ceriodaphnia dubia. Surface water samples were collected by TVA Field engineering personnel from Clinch River Mile 19.0 and Mile 22.0 on July 21, 23, and 26. Samples were split and provided to the CR-ERP and TVA toxicology laboratories for testing. Exposure of test organisms to these samples resulted in no toxicity (survival, growth, or reproduction) to either species in testing conducted by TVA. Attachments to this report include: Chain of custody forms -- originals; Toxicity test bench sheets and statistical analyses; and Reference toxicant test information.
Date:
December 31, 1993
Creator:
Russell, C.L.
Object Type:
Report
System:
The UNT Digital Library
Static renewal tests using Pimephales promelas (fathead minnows). Clinch River-Environmental Restoration Program (CR-ERP) study, ambient water toxicity
Clinch River-Environmental Restoration Program (CR-ERP) personnel and Tennessee Valley Authority (TVA) personnel conducted a study during the week of October 21--28, 1993. The organisms specified for testing were larval fathead minnows, Pimephales promelas, and the daphnid, Ceriodaphnia dubia. Due to serious reproduction/embryo abortion problems with the TVA daphnid cultures, TVA conducted tests during this study period using only fathead minnows. Surface water samples were collected by TVA Field Engineering personnel from Poplar Creek Mile 2.9, Mile 4.3, and Mile 5.1 on October 20, 22, and 25. Samples were split and provided to the CR-ERP and TVA toxicology laboratories for testing. Exposure of test organisms to these samples resulted in no toxicity (survival or growth) in testing conducted by TVA. Attachments to this report include: Chain of custody forms -- originals; Toxicity test bench sheets and statistical analyses; and Reference toxicant test information.
Date:
December 31, 1993
Creator:
Simbeck, D.J.
Object Type:
Report
System:
The UNT Digital Library
Statistical crack mechanics
This note is an approach to modelling of explosive and propellant sensitivity. Viewgraphs are included.
Date:
December 31, 1993
Creator:
Dienes, J. K.
Object Type:
Article
System:
The UNT Digital Library
Status and progress of the RERTR Program
The progress of the Reduced Enrichment Research and Test Reactor (RERTR) Program is described. The major events, findings, and activities of 1993 are reviewed after a brief summary of the results which the RERTR Program had achieved by the end of 1992 in collaboration with its many international partners.
Date:
December 31, 1993
Creator:
Travelli, A.
Object Type:
Report
System:
The UNT Digital Library
Status of aeromagnetic survey coverage of Yucca Mountain and vicinity to a radius of about 140 kilometers, southwestern Nevada and southeastern California, 1992
Fifty aeromagnetic surveys in the southwestern part of Nevada and the southeastern part of California have been evaluated to assess the quality and coverage of aeromagnetic data within 140 kilometers (km) of a potential nuclear waste repository at Yucca Mountain, Nevada. The compilation shows that all the study area is covered by aeromagnetic surveys, but in some areas, particularly in the Death Valley region, new surveys flown with closer flight line spacing and lower elevations than the existing coverage are needed. In addition, the California part of the study area needs to be analytically continued downward to 305 meters (m) above ground level to provide a consistent data set for interpretation of subsurface geologic structures.
Date:
December 31, 1993
Creator:
Sikora, R. F.; Ponce, D. A. & Oliver, H. W.
Object Type:
Report
System:
The UNT Digital Library
Status of LLNL Hot-Recycled-Solid oil shale retort
We have investigated the technical and economic barriers facing the introduction of an oil shale industry and we have chosen Hot-Recycled-Solid (HRS) oil shale retorting as the primary advanced technology of interest. We are investigating this approach through fundamental research, operation of a 4 tonne-per-day, HRS pilot plant and development of an Oil Shale Process (OSP) mathematical model. Over the last three years, from June 1991 to June 1993, we completed a series of runs (H10--H27) using the 4-TPD pilot plant to demonstrate the technical feasibility of the HRS process and answer key scale-up questions. With our CRADA partners, we seek to further develop the HRS technology, maintain and enhance the knowledge base gained over the past two decades through research and development by Government and industry and determine the follow on steps needed to advance the technology towards commercialization. The LLNL Hot-Recycled-Solid process has the potential to improve existing oil shale technology. It processes oil shale in minutes instead of hours, reducing plant size. It processes all oil shale, including fines rejected by other processes. It provides controls to optimize product quality for different applications. It co-generates electricity to maximize useful energy output. And, it produces negligible SO{sub 2} …
Date:
December 31, 1993
Creator:
Baldwin, D. E. & Cena, R. J.
Object Type:
Article
System:
The UNT Digital Library