Environmental impacts of ocean disposal of CO{sub 2} (open access)

Environmental impacts of ocean disposal of CO{sub 2}

This project has examined the impacts from the marine disposal of carbon dioxide based on the current state of knowledge.
Date: December 31, 1995
Creator: Adams, E.; Herzog, H.; Auerbach, D. & Caulfield, J.
System: The UNT Digital Library
Deflagration-induced pressure and temperature transients in a waste storage facility (open access)

Deflagration-induced pressure and temperature transients in a waste storage facility

This paper presents a study for a facility where a deflagration of flammable vapors takes place, and the generated pressure and temperature transients are analyzed to evaluate the pressure differentials induced on the various components of the facility to assesses their structural integrity. The temperature profiles are also analyzed to assess the qualification of the equipment that is required to operate during and after such an accident.
Date: December 31, 1995
Creator: Ades, M. J. & Polizzi, L. M.
System: The UNT Digital Library
Atomic structure of active sites in O{sub 2} reduction on Au(111)/Tl{sub ad} electrodes in acid and alkaline solutions (open access)

Atomic structure of active sites in O{sub 2} reduction on Au(111)/Tl{sub ad} electrodes in acid and alkaline solutions

Surface x-ray scattering has been used to determine the structure of Tl adlayers on the Au(111) electrode surface during the course of 0{sub 2} reduction. 0. reduction is considerably catalyzed by Ti adlayers on Au(111). The half-wave potential is shifted to more positive values in the presence of the Ti adlayer. In both, acid and alkaline solutions TI causes a change in the reaction mechanism from a 2-ereduction to a 4e-reduction in a limited potential range. The in-plane X-ray diffraction measurements revealed that the close-packed rotated-hexagonal Ti phase, which exists in the potential range between -0.4V and the bulk TI deposition at {approx}{minus} 0.7V, has a lower activity for 0. reduction than the low-coverage phases in both solutions. It supports a 2e-reduction.0{sub 2} reduction does not change the TI coverage in this phase but causes a significant decrease of the in-plane diffracted intensity. The lower coverage phases which exist at more positive potentials, viz., aligned hexagonal in alkaline solution and patches of the (2 {times} 2)TI phase in acid solution, are conducive to a 4e-reduction. The diffraction intensity from these two phases, however, vanishes quickly during O{sub 2} reduction. It appears that the TI coverage remains on the surface unchanged. …
Date: December 31, 1995
Creator: Adzic, R. R. & Wang, J. X.
System: The UNT Digital Library
Intercooler Flow Path for Gas Turbines: CFD Design and Experiments (open access)

Intercooler Flow Path for Gas Turbines: CFD Design and Experiments

The Advanced Turbine Systems (ATS) program was created by the U.S. Department of Energy to develop ultra-high efficiency, environmentally superior, and cost competitive gas turbine systems for generating electricity. Intercooling or cooling of air between compressor stages is a feature under consideration in advanced cycles for the ATS. Intercooling entails cooling of air between the low pressure (LP) and high pressure (HP) compressor sections of the gas turbine. Lower air temperature entering the HP compressor decreases the air volume flow rate and hence, the compression work. Intercooling also lowers temperature at the HP discharge, thus allowing for more effective use of cooling air in the hot gas flow path.
Date: December 31, 1995
Creator: Agrawal, A. K.; Gollahalli, S. R. & Carter, F. L.
System: The UNT Digital Library
A new look at positron production from heavy-ion collisions: Results from apex (open access)

A new look at positron production from heavy-ion collisions: Results from apex

A new solenoidal spectrometer, designed to study the production mechanism of electrons and positrons in heavy-ion collisions, has been constructed at Argonne National Laboratory. The spectrometer has been used to study the {sup 238}U + {sup 181}Ta system at 5.95, 6.10, and 6.30 MeV/u and the {sup 238}U + {sup 232}Th system at 5.95 MeV/u. These bombarding energies cover the energy region where previous experiments have reported sharp sum-energy lines. No evidence is found for sharp peaks in the present data. For the specific case of the isolated decay of a neutral particle of mass 1.4--2.1 MeV/c{sup 2} the upper limits on cross sections obtained from the present data are significantly less than the previously reported cross sections.
Date: December 31, 1995
Creator: Ahmad, I.; Back, B. B. & Austin, S. M.
System: The UNT Digital Library
The positron peak puzzle - recent results from APEX (open access)

The positron peak puzzle - recent results from APEX

Results are presented from a new experiment, APEX, designed to study the previously reported sharp lines in sum-energy spectra of positrons and electrons produced in collisions of very heavy ions. Data have been collected for {sup 238}U+{sup 181}Ta and {sup 238}U+{sup 232}Th. No evidence is found for narrow structures similar to those previously reported. For the specific case of the isolated decay of a neutral particle of mass 1.4-2.1 MeV/c{sup 2}, the upper limits on cross sections obtained are significantly less than previously reported. Data are also presented for internal pair conversion in {sup 206}Pb. These results are used to set limits for the possible contribution to the pair yield of a 1780 keV transition in {sup 238}U observed in heavy-ion gamma-ray coincidence measurements.
Date: December 31, 1995
Creator: Ahmad, I.; Back, B.B. & Kutschera, W.
System: The UNT Digital Library
Thermal diffusivity imaging of continuous fiber ceramic composite materials and components (open access)

Thermal diffusivity imaging of continuous fiber ceramic composite materials and components

Continuous-fiber ceramic matrix composites (CFCCs) are currently being developed for various high-temperature applications, including use in advanced turbine engines. In such composites, the condition of the interfaces between the fibers and matrix or between laminae in a two-dimensional weave lay-up are critical to the mechanical and thermal behavior of the component. A nondestructive evaluation method that could be used to assess the interface condition and/or detect other `defects` has been developed at Argonne National Laboratory (ANL) and uses infrared thermal imaging to provide `single-shot` full- field quantitative measurement of the distribution of thermal diffusivity in large components. By applying digital filtering, interpolation, and least-squares-estimation techniques for noise reduction, shorter acquisition and analysis times have been achieved with submillimeter spatial resolution for materials with a wide range of `thermal thicknesses`. The system at ANL has been used to examine the effects of thermal shock, oxidation treatment, density variations, and variations in fiber coating in a full array of test specimens. In addition, actual subscale CFCC components of nonplanar geometries have been inspected for manufacturing-induced variations in thermal properties.
Date: December 31, 1995
Creator: Ahuja, S.; Ellingson, W.A.; Steckenrider, J.S. & King, S.
System: The UNT Digital Library
Possible use of the AGS linac for proton therapy (open access)

Possible use of the AGS linac for proton therapy

The BNL 200 MeV linac presently provides beam for the AGS high energy physics program and for isotope production at the Brookhaven Linac Isotope Producer (BLIP) facility. There is now a proposal to develop a proton therapy facility which would also use the linac beam. Approximately 1% of the current in each linac beam pulse would be diverted from BLIP, down an existing transport line, to the proposed new facility. This paper focuses on the basic design of the facility, particularly the accelerator issues. The planned transport line layout is presented, along with a description of the energy and intensity control, and beam delivery systems. In the initial phase, we are planning one 360{degrees} vertical gantry and one horizontal treatment room.
Date: December 31, 1995
Creator: Alessi, J. G.; Chanana, A.; Dilmanian, F. A.; Lee, Y. Y.; Raparia, D.; Tuozzolo, J. et al.
System: The UNT Digital Library
Applications of lasers to the solution of environmental problems (open access)

Applications of lasers to the solution of environmental problems

This presentation will focus on current work in the Ames Laboratory where laser ablation is being used for both analytical sampling and metal surface cleaning. Examples will be presented demonstrating the utility of optical spectroscopy for monitoring laser ablation processes.
Date: December 31, 1995
Creator: Allen, L.; Pang, H.-M. & Edelson, M. C.
System: The UNT Digital Library
Mapping site-specific endonuclease binding to DNA by direct imaging with AFM (open access)

Mapping site-specific endonuclease binding to DNA by direct imaging with AFM

Physical mapping of DNA can be accomplished by direct AFM imaging of site specific proteins bound to DNA molecules. Using Gln-111, a mutant of EcoRI endonuclease with a specific affinity for EcoRI sites 1,000 times greater than wild type enzyme but with cleavage rate constants reduced by a factor of 10{sup 4}, the authors demonstrate site-specific mapping by direct AFM imaging. Images are presented showing specific-site binding of Gln-111 to plasmids having either one (pBS{sup +}) or two (pMP{sup 32}) EcoRI sites. Identification of the Gln-111/DNA complex is greatly enhanced by biotinylation of the complex followed by reaction with streptavidin gold prior to imaging. Image enhancement coupled with improvements in the preparation techniques for imaging large DNA molecules, such as lambda DNA (47 kb), has the potential to contribute to direct AFM restriction mapping of cosmid-sized genomic DNAs.
Date: December 31, 1995
Creator: Allison, D. P.; Thundat, T.; Doktycz, M. J.; Kerper, P. S.; Warmack, R. J.; Modrich, P. et al.
System: The UNT Digital Library
Phosphor Thermometry of Gas Turbine Surfaces (open access)

Phosphor Thermometry of Gas Turbine Surfaces

This paper describes a nondestructive method for thermometry applicable to ceramic surfaces and coatings. To date our primary application has been to turbine engine and air vehicle surfaces. This method makes use of thermally sensitive phosphors many of which, as it turns out, are also ceramics. These materials fluoresce when suitably illuminated by ultraviolet light. The fluorescence intensity and decay time are well-behaved functions of temperature and therefore serve as reliable indicators of the temperature of the substrate to which the fluorescing material is attached. It is a non- contact method in that the light delivery and collection optics can be remotely located. A range of phosphor materials have been tested and any temperature ranging from 8 to 1900 K can be measured by selection of the appropriate phosphor. Turbine blades, vanes, thermal barrier coatings, and panels are examples of surfaces which have been diagnosed to date in either engine or engine-simulation facilities. A variety of coating methods are used, including electron-beam deposition, radio-frequency sputtering, and curing with inorganic binders. This paper summarizes the results to date and status of this technology.
Date: December 31, 1995
Creator: Allison, Steven W.; Beshears, David L.; Cates, Michael R.; Noel, Bruce W. & Turley, W. D.
System: The UNT Digital Library
Selecting reasonable future land use scenarios (open access)

Selecting reasonable future land use scenarios

This paper examines a process to help select the most reasonable future land use scenario for hazardous waste and/or low-level radioactive waste disposal sites. The process involves evaluating future land use scenarios ab applying selected criteria currently used by commercial mortgage companies to determine the feasibility of obtaining a loan for purchasing such land. The basis for the process is that only land use activities for which a loan can be obtained well be considered. To examine the process, a low-level radioactive waste site, the Radioactive Waste Management Complex at the Idaho National Engineering Laboratory, is used as an example. The authors suggest that the process is a very precise, comprehensive, and systematic approach for determining reasonable future use of land. Implementing such a process will help enhance the planning, decisionmaking, safe management, and cleanup of present and future disposal facilities.
Date: December 31, 1995
Creator: Allred, W.E. & Smith, R.W.
System: The UNT Digital Library
Sensitivity studies of unsaturated groundwater flow modeling for groundwater travel time calculations at Yucca Mountain, Nevada (open access)

Sensitivity studies of unsaturated groundwater flow modeling for groundwater travel time calculations at Yucca Mountain, Nevada

Unsaturated flow has been modeled through four cross-sections at Yucca Mountain, Nevada, for the purpose of determining groundwater particle travel times from the potential repository to the water table. This work will be combined with the results of flow modeling in the saturated zone for the purpose of evaluating the suitability of the potential repository under the criteria of 10CFR960. One criterion states, in part, that the groundwater travel time (GWTT) from the repository to the accessible environment must exceed 1,000 years along the fastest path of likely and significant radionuclide travel. Sensitivity analyses have been conducted for one geostatistical realization of one cross-section for the purpose of (1) evaluating the importance of hydrological parameters having some uncertainty and (2) examining conceptual models of flow by altering the numerical implementation of the conceptual model (dual permeability (DK) and the equivalent continuum model (ECM). Results of comparisons of the ECM and DK model are also presented in Ho et al.
Date: December 31, 1995
Creator: Altman, S. J.; Ho, C. K.; Arnold, B. W. & McKenna, S. A.
System: The UNT Digital Library
Broadband Frequency ECR Ion Source Concepts with Large Resonant Plasma Volumes (open access)

Broadband Frequency ECR Ion Source Concepts with Large Resonant Plasma Volumes

New techniques are proposed for enhancing the performances of ECR ion sources. The techniques are based on the use of high-power, variable-frequency, multiple-discrete-frequency, or broadband microwave radiation, derived from standard TWT technology, to effect large resonant ``volume`` ECR sources. The creation of a large ECR plasma ``volume`` permits coupling of more power into the plasma, resulting in the heating of a much larger electron population to higher energies, the effect of which is to produce higher charge state distributions and much higher intensities within a particular charge state than possible in present forms of the ECR ion source. If successful, these developments could significantly impact future accelerator designs and accelerator-based, heavy-ion-research programs by providing multiply-charged ion beams with the energies and intensities required for nuclear physics research from existing ECR ion sources. The methods described in this article can be used to retrofit any ECR ion source predicated on B-minimum plasma confinement techniques.
Date: December 31, 1995
Creator: Alton, G. D.
System: The UNT Digital Library
Future Prospects for ECR Ion Sources With Improved Charge State Distributions (open access)

Future Prospects for ECR Ion Sources With Improved Charge State Distributions

Despite the steady advance in the technology of the ECR ion source, present art forms have not yet reached their full potential in terms of charge state and intensity within a particular charge state, in part, because of the narrow band width. single-frequency microwave radiation used to heat the plasma electrons. This article identifies fundamentally important methods which may enhance the performances of ECR ion sources through the use of: (1) a tailored magnetic field configuration (spatial domain) in combination with single-frequency microwave radiation to create a large uniformly distributed ECR ``volume`` or (2) the use of broadband frequency domain techniques (variable-frequency, broad-band frequency, or multiple-discrete-frequency microwave radiation), derived from standard TWT technology, to transform the resonant plasma ``surfaces`` of traditional ECR ion sources into resonant plasma ``volume``. The creation of a large ECR plasma ``volume`` permits coupling of more power into the plasma, resulting in the heating of a much larger electron population to higher energies, thereby producing higher charge state ions and much higher intensities within a particular charge state than possible in present forms of` the source. The ECR ion source concepts described in this article offer exciting opportunities to significantly advance the-state-of-the-art of ECR technology and …
Date: December 31, 1995
Creator: Alton, G. D.
System: The UNT Digital Library
Selection of Targets and Ion Sources for RIB Generation at the Holifield Radioactive Ion Beam Facility (open access)

Selection of Targets and Ion Sources for RIB Generation at the Holifield Radioactive Ion Beam Facility

In this report, the authors describe the performance characteristics for a selected number of target ion sources that will be employed for initial use at the Holifield Radioactive Ion Beam Facility (HRIBF) as well as prototype ion sources that show promise for future use for RIB applications. A brief review of present efforts to select target materials and to design composite target matrix/heat-sink systems that simultaneously incorporate the short diffusion lengths, high permeabilities, and controllable temperatures required to effect fast and efficient diffusion release of the short-lived species is also given.
Date: December 31, 1995
Creator: Alton, G. D.
System: The UNT Digital Library
Selection of RIB Targets Using Ion Implantation at the Holifield Radioactive Ion Beam Facility (open access)

Selection of RIB Targets Using Ion Implantation at the Holifield Radioactive Ion Beam Facility

Among several major challenges posed by generating and accelerating adequate intensities of RIBs, selection of the most appropriate target material is perhaps the most difficult because of the requisite fast and selective thermal release of minute amounts of the short-lived product atoms from the ISOL target in the presence of bulk amounts of target material. Experimental studies are under way at the Oak Ridge National Laboratory (ORNL) which are designed to measure the time evolution of implanted elements diffused from refractory target materials which are candidates for forming radioactive ion beams (RIBs) at the Holifield Radioactive Ion Beam Facility (HRIBF). The diffusion coefficients are derived by comparing experimental data with numerical solutions to a one-dimensional form of Fick`s second law for ion implanted distributions. In this report, we describe the experimental arrangement, experimental procedures, and provide time release data and diffusion coefficients for releasing ion implanted {sup 37}Cl from Zr{sub 5}Si{sub 3} and {sup 75}As, {sup 79}Br, and {sup 78}Se from Zr{sub 5}Ge{sub 3} and estimates of the diffusion coefficients for{sup 35}Cl, {sup 63}Cu, {sup 65}Cu, {sup 69}Ga and {sup 71}Ga diffused from BN; {sup 35}Cl, {sup 63}Cu, {sup 65}Cu, {sup 69}Ga, {sup 75}As, and {sup 78}Se diffused from C; …
Date: December 31, 1995
Creator: Alton, G. D. & Dellwo, J.
System: The UNT Digital Library
A High-Efficiency Positive (Negative) Surface Ionization Source for Rib Generation (open access)

A High-Efficiency Positive (Negative) Surface Ionization Source for Rib Generation

A versatile, new concept, spherical-geometry, positive (negative) surface-ionization source has been designed and fabricated which will have the capability of generating both positive- and negative-ion beams without mechanical changes to the source. The source utilizes a highly permeable, high-work-function Ir ionizer ({phi} {congruent} 5. 229 eV) for ionizing highly electropositive atoms/molecules; while for negative-surface ionization, the work function is lowered to {phi} {congruent} 1.43 eV by continually feeding cesium vapor through the ionizer matrix. The use of this technique for negative ion beam generation has the potential of overcoming the chronic poisoning effects experienced with LaB{sub 6} while enhancing considerably the efficiency for negative surface ionization of atomic and molecules with intermediate electron affinities. The flexibility of operation in either mode makes it especially attractive for RIB applications and, therefore, the source will be used as a complementary replacement for the high-temperature electron impact ionization sources presently in use at the HRIBF. The design features and operational principles of the source will be described in this report.
Date: December 31, 1995
Creator: Alton, G. D. & Mills, G. D.
System: The UNT Digital Library
A Positive (Negative) Surface Ionization Source Concept for RIB Generation (open access)

A Positive (Negative) Surface Ionization Source Concept for RIB Generation

A novel, versatile, new concept, spherical-geometry, positive (negative) surface-ionization source has been designed and fabricated which will have the capability of generating both positive- and negative-ion beams without mechanical changes to the source. The source utilizes a highly permeable, high-work-function Ir ionizer ({phi}{approximately} = 5.29 eV) for ionizing highly electropositive atoms/molecules; while for negative-surface ionization, the work function is lowered to {phi} {approximately} = 1.43 eV by continually feeding cesium vapor through the ionizer matrix. The use of Cs to effect low work function surfaces for negative ion beam generation has the potential of overcoming the chronic poisoning effects experienced with LaB{sub 6} while enhancing the probability for negative ion formation of atomic and molecular species with low to intermediate electron affinities. The flexibility of operation in either mode makes it especially attractive for RIB applications and, therefore, the source will be used as a complementary replacement for the high-temperature electron impact ionization sources presently in use at the HRIBF The design features and operational principles of the source will be described in this report.
Date: December 31, 1995
Creator: Alton, G. D. & Mills, G. D.
System: The UNT Digital Library
A Combined Thermal Dissociation and Electron Impact Ionization Source for RIB Generation (open access)

A Combined Thermal Dissociation and Electron Impact Ionization Source for RIB Generation

The probability for simultaneously dissociating and efficiently ionizing the individual atomic constituents of molecular feed materials with conventional, hot-cathode, electron-impact ion sources is low and consequently, the ion beams from these sources often appear as mixtures of several molecular sideband beams. This fragmentation process leads to dilution of the intensity of the species of interest for RIB applications where beam intensity is at a premium. We have conceived an ion source that combines the excellent molecular dissociation properties of a thermal dissociator and the high ionization efficiency characteristics of an electron impact ionization source that will, in principle, overcome this handicap. The source concept will be evaluated as a potential candidate for use for RIB generation at the Holifield Radioactive Ion Beam Facility (HRIBF), now under construction at the Oak Ridge National Laboratory. The design features and principles of operation of the source are described in this article.
Date: December 31, 1995
Creator: Alton, G. D. & Williams, C.
System: The UNT Digital Library
A New Concept Tandem Thermal Dissociator/Electron Impact Ion Source for RIB Generation (open access)

A New Concept Tandem Thermal Dissociator/Electron Impact Ion Source for RIB Generation

An innovative thermal dissociation/electron impact ionization positive ion source is presently under design at the Oak Ridge National Laboratory for potential use for generating RIBs at the Holifield Radioactive Ion Beam Facility (HRIBF). Because of the low probability of simultaneously dissociating and efficiently ionizing the individual atomic constituents with conventional, hot-cathode, electron-impact ion sources, the ion beams extracted from these sources often appear as a mixture of several molecular sideband beams. In this way, the intensity of the species of interest is diluted. We have conceived an Ion source that combines the excellent molecular dissociation properties of a thermal dissociator and the high efficiency characteristics of an electron impact ionization source. If the concept proves to be a viable option, the source will be used as a complement to the electron beam plasma ion sources already in use at the HRIBF. The design features and principles of operation of the source are described in this article.
Date: December 31, 1995
Creator: Alton, G. D. & Williams, C.
System: The UNT Digital Library
Robust model error localization for damage detection and finite element model update (open access)

Robust model error localization for damage detection and finite element model update

A new method for identifying the location of finite element model errors given test-identified frequencies and mode shape data is presented. The new method builds on the concept of the modal force error vector, which is the undamped impedance of the given finite element model at each identified frequency multiplied by the corresponding identified mode shape. In order to mitigate the problems associated with reducing analytical models to the set of measurement degrees of freedom, a mode shape projection algorithm is utilized. The projection algorithm is a linear least-squares method which can be controlled to minimize bias caused by model errors. The localization indicator is then defined by the modal force error and a degree of freedom dependent normalization based on the variance of the identified frequencies and mode shapes. The performance of the method in localizing structural damage is examined using experimental data.
Date: December 31, 1995
Creator: Alvin, Kenneth F.
System: The UNT Digital Library
Steerable/distance enhanced penetrometer delivery system (open access)

Steerable/distance enhanced penetrometer delivery system

The first steps toward contaminant plume contaminant and remediation are detection and mapping of the plume. Penetrometers can be used to map the plume efficiently and also provide the means for in-situ sampling and remediation. In traditional penetrometer applications, the instrumentation package located at the tip measures soil resistance. However, for environmental monitoring purposes, an array of environmental sensors is packed inside the penetrometer rods for in-situ sampling and analysis, or for collection of laboratory samples. At present, penetrometer applications are limited primarily to vertical pushes and because of their heavy weight, the use of penetrometer trucks over shallow buried storage tanks is restricted. To close the technology gap in the use of penetrometers for environmental purposes, UTD took the initiative by developing a new position location device referred to as POLO (short for POsition LOcator), which provides real-time position location without blocking downhole access for environmental sensors. The next step taken was the initiation of work to make penetrometers steerable and capable of greater penetration capabilities. The product of this work will be a relatively lightweight vibratory steerable penetrometer that can provide greater penetration capability than traditional penetrometers of the same weight, permitting applications over shallow buried storage tanks.
Date: December 31, 1995
Creator: Amini, A.; Shenhar, J. & Lum, K.D.
System: The UNT Digital Library
Development on inelastic analysis acceptance criteria for radioactive material transportation packages (open access)

Development on inelastic analysis acceptance criteria for radioactive material transportation packages

The response of radioactive material transportation packages to mechanical accident loadings can be more accurately characterized by non-linear dynamic analysis than by the ``Equivalent dynamic`` static elastic analysis typically used in the design of these packages. This more accurate characterization of the response can lead to improved package safety and design efficiency. For non-linear dynamic analysis to become the preferred method of package design analysis, an acceptance criterion must be established that achieves an equivalent level of safety as the currently used criterion defined in NRC Regulatory Guide 7.6 (NRC 1978). Sandia National Laboratories has been conducting a study of possible acceptance criteria to meet this requirement. In this paper non-linear dynamic analysis acceptance criteria based on stress, strain, and strain-energy-density will be discussed. An example package design will be compared for each of the design criteria, including the approach of NRC Regulatory Guide 7.6.
Date: December 31, 1995
Creator: Ammerman, D.J. & Ludwigsen, J.S.
System: The UNT Digital Library