Simulation of Alpha-Channeling in Mirror Machines (open access)

Simulation of Alpha-Channeling in Mirror Machines

Applying α-channeling techniques to mirror machines can significantly increase their effective reactivity, thus making open configurations more advantageous for practical fusion. A large fraction of α particle energy can be extracted using rf waves. Effects employed to cool α particles can also in principle be used to heat the fusion ions; the possibility to design a configuration of rf waves which could be used to perform both tasks is demonstrated.
Date: March 17, 2008
Creator: A.I. Zhmoginov, N.J. Fisch
Object Type: Report
System: The UNT Digital Library

Reduction of U(VI) Complexes by Anthraquinone Disulfonate: Experiment and Molecular Modeling

Past studies demonstrate that complexation will limit abiotic and biotic U(VI) reduction rates and the overall extent of reduction. However, the underlying basis for this behavior is not understood and presently unpredictable across species and ligand structure. The central tenets of these investigations are: (1) reduction of U(VI) follows the electron-transfer (ET) mechanism developed by Marcus; (2) the ET rate is the rate-limiting step in U(VI) reduction and is the step that is most affected by complexation; and (3) Marcus theory can be used to unify the apparently disparate U(VI) reduction rate data and as a computational tool to construct a predictive relationship.
Date: March 17, 2004
Creator: Ainsworth, C. C.; Wang, Z.; Rosso, K. M.; Wagnon, K. & Fredrickson, J. K.
Object Type: Presentation
System: The UNT Digital Library
Les Houches Physics at TeV Colliders 2005 Beyond the Standard Model Working Group: Summary Report (open access)

Les Houches Physics at TeV Colliders 2005 Beyond the Standard Model Working Group: Summary Report

The work contained herein constitutes a report of the ''Beyond the Standard Model'' working group for the Workshop ''Physics at TeV Colliders'', Les Houches, France, 2-20 May, 2005. We present reviews of current topics as well as original research carried out for the workshop. Supersymmetric and non-supersymmetric models are studied, as well as computational tools designed in order to facilitate their phenomenology.
Date: March 17, 2006
Creator: Allanach, B. C.; Grojean, C.; Skands, P.; Accomando, E.; Azuelos, G.; Baer, H. et al.
Object Type: Article
System: The UNT Digital Library
Invert Effective Thermal Conductivity Calculation (open access)

Invert Effective Thermal Conductivity Calculation

The objective of this calculation is to evaluate the temperature-dependent effective thermal conductivities of a repository-emplaced invert steel set and surrounding ballast material. The scope of this calculation analyzes a ballast-material thermal conductivity range of 0.10 to 0.70 W/m {center_dot} K, a transverse beam spacing range of 0.75 to 1.50 meters, and beam compositions of A 516 carbon steel and plain carbon steel. Results from this calculation are intended to support calculations that identify waste package and repository thermal characteristics for Site Recommendation (SR). This calculation was developed by Waste Package Department (WPD) under Office of Civilian Radioactive Waste Management (OCRWM) procedure AP-3.12Q, Revision 1, ICN 0, Calculations.
Date: March 17, 2000
Creator: Anderson, M. J.; Wade, H. M. & Mitchell, T. L.
Object Type: Report
System: The UNT Digital Library
Hydrogen Separation Membranes Annual Report for FY 2008. (open access)

Hydrogen Separation Membranes Annual Report for FY 2008.

The objective of this work is to develop dense ceramic membranes for separating hydrogen from other gaseous components in a nongalvanic mode, i.e., without using an external power supply or electrical circuitry. The goal of this project is to develop dense hydrogen transport membranes (HTMs) that nongalvanically (i.e., without electrodes or external power supply) separate hydrogen from gas mixtures at commercially significant fluxes under industrially relevant operating conditions. HTMs will be used to separate hydrogen from gas mixtures such as the product streams from coal gasification, methane partial oxidation, and water-gas shift reactions. Potential ancillary uses of HTMs include dehydrogenation and olefin production, as well as hydrogen recovery in petroleum refineries and ammonia synthesis plants, the largest current users of deliberately produced hydrogen. This report describes progress that was made during Fy 2008 on the development of HTM materials.
Date: March 17, 2009
Creator: Balachandran, U.; Dorris, S. E.; Emerson, J. E.; Lee, T. H.; Lu, Y.; Park, C. Y. et al.
Object Type: Report
System: The UNT Digital Library
Group Theoretical Analysis of Vibrational Modes, Rovibronic Levels and Nuclear Spin Statistics of extended aromatic C48N12 Azafullerene (open access)

Group Theoretical Analysis of Vibrational Modes, Rovibronic Levels and Nuclear Spin Statistics of extended aromatic C48N12 Azafullerene

We have presented a group theoretical analysis of the vibrational modes and rovibronic levels of a novel extended aromatic C{sub 48}N{sub 12} azafullerene. The nuclear spin multiplets and statistical weights of {sup 14}N spin-1 bosons, vibrational and rotational analysis and computed vibrational spectra are provided. We have also predicted the properties of the {sup 3}A{sub u}, {sup 3}E{sub g}, and {sup 3}E{sub u} excited states of C{sub 48}N{sub 12} that lie 1.9 eV above the {sup 1}A{sub g} ground state, and that the {sup 3}E{sub g} and {sup 3}E{sub u} states would undergo Jahn-Teller distortion into chiral structures with no symmetry and an achiral structure with C{sub i} symmetry.
Date: March 17, 2004
Creator: Balasubramanian, K
Object Type: Article
System: The UNT Digital Library
Spectroscopic Properties of Novel Aromatic Metal Clusters: NaM4 (M=Al, Ga, In) and their Cations and Anions (open access)

Spectroscopic Properties of Novel Aromatic Metal Clusters: NaM4 (M=Al, Ga, In) and their Cations and Anions

The ground and several excited states of metal aromatic clusters, namely NaM4 and NaM{sub 4}{sup {+-}} (M=Al, Ga, In) clusters have been investigated by employing complete activespace self-consistent-field (CASSCF) followed by Multi-reference singles and doubles configuration interaction (MRSDCI) computations that included up to 10 million configurations and other methods. The ground states NaM{sub 4}{sup -} of aromatic anions are found to be symmetric C{sub 4v} ({sup 1}A{sub 1}) electronic states with ideal square pyramid geometries. While the ground state of NaIn4 is also predicted to be a symmetric C{sub 4v} ({sup 2}A{sub 1}) square pyramid, the ground state of the NaAl4 cluster is found to have a C{sub 2v} ({sup 2}A{sub 1}) pyramid with a rhombus base and the ground state of NaGa{sub 4} possesses a C{sub 2v} ({sup 2}A{sub 1}) pyramid with a rectangle base. In general these structures exhibit 2 competing geometries, viz., an ideal C{sub 4v} structure and a distorted rhomboidal or rectangular pyramid structure (C{sub 2v}). All of the ground states of the NaM{sub 4}{sup +} (M= Al, Ga, In) cations are computed to be C{sub 2v} ({sup 3}A{sub 2}) pyramids with rhombus bases. The equilibrium geometries, vibrational frequencies, dissociation energies, adiabatic ionization potentials, adiabatic electron …
Date: March 17, 2004
Creator: Balasubramanian, K & Zhao, C
Object Type: Article
System: The UNT Digital Library
The Heavy Ion Fusion Program in the USA (open access)

The Heavy Ion Fusion Program in the USA

The U.S. Department of Energy has established a new, larger inertial fusion energy program. To manage program growth, we have developed a new inertial fusion energy research and we have established a Virtual National Laboratory for Heavy Ion Fusion. There has been significant technical progress. Improvements in target design have reduced the predicted energy requirements by approximately a factor of two. There have also been important experiments on chamber dynamics and other inertial fusion technologies. The accelerator program has completed a number of small-scale experiments. Experiments with driver-scale beams are being designed -- including experiments with driver-scale ion sources and injectors. Finally we are developing the technologies needed to build a major research facility known as the Integrated Research Experiment (IRE)
Date: March 17, 2000
Creator: Bangerter, R.O.
Object Type: Article
System: The UNT Digital Library
On Sub-linear Convergence for Linearly Degenerate Waves in Capturing Schemes (open access)

On Sub-linear Convergence for Linearly Degenerate Waves in Capturing Schemes

A common attribute of capturing schemes used to find approximate solutions to the Euler equations is a sub-linear rate of convergence with respect to mesh resolution. Purely nonlinear jumps, such as shock waves produce a first-order convergence rate, but linearly degenerate discontinuous waves, where present, produce sub-linear convergence rates which eventually dominate the global rate of convergence. The classical explanation for this phenomenon investigates the behavior of the exact solution to the numerical method in combination with the finite error terms, often referred to as the modified equation. For a first-order method, the modified equation produces the hyperbolic evolution equation with second-order diffusive terms. In the frame of reference of the traveling wave, the solution of a discontinuous wave consists of a diffusive layer that grows with a rate of t{sup 1/2}, yielding a convergence rate of 1/2. Self-similar heuristics for higher order discretizations produce a growth rate for the layer thickness of {Delta}t{sup 1/(p+1)} which yields an estimate for the convergence rate as p/(p+1) where p is the order of the discretization. In this paper we show that this estimated convergence rate can be derived with greater rigor for both dissipative and dispersive forms of the discrete error. In …
Date: March 17, 2008
Creator: Banks, J W; Aslam, T & Rider, W J
Object Type: Article
System: The UNT Digital Library
Post-Closure RCRA Groundwater Monitoring Plan for the 216-S-10 Pond and Ditch (open access)

Post-Closure RCRA Groundwater Monitoring Plan for the 216-S-10 Pond and Ditch

The purpose of this plan is to provide a post-closure groundwater monitoring program for the 216-S-10 Pond and Ditch (S-10) treatment, storage, and/or disposal (TSD) unit. The plan incorporates the sum of knowledge about the potential for groundwater contamination to originate from the S-10, including groundwater monitoring results, hydrogeology, and operational history. The S-10 has not received liquid waste since October 1991. The closure of S-10 has been coordinated with the 200-CS-1 source operable unit in accordance with the Tri-Party Agreement interim milestones M-20-39 and M-15-39C. The S-10 is closely situated among other waste sites of very similar operational histories. The proximity of the S-10 to the other facilities (216-S-17 pond, 216-S-11 Pond, 216-S-5,6 cribs, 216-S-16 ditch and pond, and 216-U-9 ditch) indicate that at least some observed groundwater contamination beneath and downgradient of S-10 could have originated from waste sites other than S-10. Hence, it may not be feasible to strictly discriminate between the contributions of each waste site to groundwater contamination beneath the S-10. A post-closure groundwater monitoring network is proposed that will include the drilling of three new wells to replace wells that have gone dry. When completed, the revised network will meet the intent for groundwater …
Date: March 17, 2006
Creator: Barnett, D BRENT.; Williams, Bruce A.; Chou, Charissa J. & Hartman, Mary J.
Object Type: Report
System: The UNT Digital Library
Poroelastic Analysis of Thomsen Parameters in Finely Layed VTI Media (open access)

Poroelastic Analysis of Thomsen Parameters in Finely Layed VTI Media

Thomsen's anisotropy parameters for weak elastic and poroelastic anisotropy are now commonly used in exploration, and can be conveniently expressed in terms of the layer averages of Backus. Although there are five effective shear moduli for any layered VTI medium, only one effective shear modulus for the layered system contains all the dependence of pore fluids on the elastic or poroelastic constants that can be observed in vertically polarized shear waves in VTI media. The effects of the pore fluids on this effective shear modulus can be substantial when the medium behaves in an undrained fashion, as might be expected at higher frequencies such a sonic and ultrasonic for well-logging or laboratory experiments, or at seismic frequencies for lower permeability regions of reservoirs.
Date: March 17, 2003
Creator: Berger, E. L.
Object Type: Article
System: The UNT Digital Library
Development of the 2-MV injector for HIF (open access)

Development of the 2-MV injector for HIF

The 2-MV Injector consists of a 17-cm-diameter surface ionization source, an extraction diode, and an electrostatic quadrupole (ESQ) accelerator, with maximum current of 0.8 A of potassium beam at 2 MeV. Previous performance of the Injector produced a beam with adequate current and emittance but with a hollow profile at the end of the ESQ section. We have examined the profile of the beam as it leaves the diode. The measured nonuniform beam density distribution qualitatively agrees with EGUN simulation. Implications for emittance growth in the post acceleration and transport phase will be investigated.
Date: March 17, 2000
Creator: Bieniosek, F. M.; Kwan, J. W.; Henestroza, E. & Kim, C.
Object Type: Article
System: The UNT Digital Library
Impact Analysis of Spent Fuel Dry Casks Under Accidental Drop Scenarios. (open access)

Impact Analysis of Spent Fuel Dry Casks Under Accidental Drop Scenarios.

A series of analyses were performed to assess the structural response of spent nuclear fuel dry casks subjected to various handling and on-site transfer events. The results of these analyses are being used by the Nuclear Regulatory Commission (NRC) to perform a probabilistic risk assessment (PRA). Although the PRA study is being performed for a specific nuclear plant, the PRA study is also intended to provide a framework for a general methodology that could also be applied to other dry cask systems at other nuclear plants. The dry cask system consists of a transfer cask, used for handling and moving the multi-purpose canister (MPC) that contains the fuel, and a storage cask, used to store the MPC and fuel on a concrete pad at the site. This paper describes the analyses of the casks for two loading events. The first loading consists of dropping the transfer cask while it is lowered by a crane to a concrete floor at ground elevation. The second loading consists of dropping the storage cask while it is being transferred to the concrete storage pad outdoors. Three dimensional finite element models of the transfer cask and storage cask, containing the MPC and fuel, were utilized …
Date: March 17, 2003
Creator: Braverman, J. I.; Morante, R. J.; Xu, J.; Hofmayer, C. H. & Shaukat, S. K.
Object Type: Article
System: The UNT Digital Library
Status of the MINOS Experiment (open access)

Status of the MINOS Experiment

We report on the status of the MINOS long baseline neutrino experiment presently under construction at the Fermi National Accelerator Laboratory and the Soudan mine. There is growing evidence that the solar neutrino and atmospheric neutrino anomalies [1] are the result of neutrino oscillations. The MINOS experiment is a long baseline neutrino oscillation experiment designed to study the region of parameter space indicated by the SuperKamiokande atmospheric neutrino results [2]. The experiment consists of two detectors, one with a mass of 980 tons located at Fermilab (the near detector) and the other of mass 5400 tons located 731 km away in the Soudan mine in northern Minnesota (the far detector). The third component is the neutrino beam which is currently under construction at Fermilab.
Date: March 17, 2003
Creator: Buckley-Geer, Elizabeth
Object Type: Article
System: The UNT Digital Library
Robotics Scoping Study to Evaluate Advances in Robotics Technologies that Support Enhanced Efficiencies for Yucca Mountain Repository Operations (open access)

Robotics Scoping Study to Evaluate Advances in Robotics Technologies that Support Enhanced Efficiencies for Yucca Mountain Repository Operations

This paper presents an evaluation of robotics and remote handling technologies that have the potential to increase the efficiency of handling waste packages at the proposed Yucca Mountain High-Level Nuclear Waste Repository. It is expected that increased efficiency will reduce the cost of operations. The goal of this work was to identify technologies for consideration as potential projects that the U.S. Department of Energy Office of Civilian Radioactive Waste Management, Office of Science and Technology International Programs, could support in the near future, and to assess their ''payback'' value. The evaluation took into account the robotics and remote handling capabilities planned for incorporation into the current baseline design for the repository, for both surface and subsurface operations. The evaluation, completed at the end of fiscal year 2004, identified where significant advantages in operating efficiencies could accrue by implementing any given robotics technology or approach, and included a road map for a multiyear R&D program for improvements to remote handling technology that support operating enhancements.
Date: March 17, 2005
Creator: Burgess, T.; Noakes, M. & Spampinato, P.
Object Type: Article
System: The UNT Digital Library

Reaction-Based Reactive Transport Modeling of Biological Iron(III) Reduction

The summary of this report is: (1) biogenic flux increases as hydrologic residence time decreases; (2) reaction-based reactive transport modeling can capture this effect; (3) solid-phase Fe(III) bioreduction can be sustained at long residence times in natural sediments; and (4) long-term coupled Fe(III)/U(VI) bioreduction can be sustained in natural sediments.
Date: March 17, 2004
Creator: Burgos, Bill
Object Type: Presentation
System: The UNT Digital Library
Thermal Decomposition Kinetics of HMX (open access)

Thermal Decomposition Kinetics of HMX

Nucleation-growth kinetic expressions are derived for thermal decomposition of HMX from a variety of types of data, including mass loss for isothermal and constant rate heating in an open pan, and heat flow for isothermal and constant rate heating in open and closed pans. Conditions are identified in which thermal runaway is small to nonexistent, which typically means temperatures less than 255 C and heating rates less than 1 C/min. Activation energies are typically in the 140 to 165 kJ/mol regime for open pan experiments and about 150-165 kJ/mol for sealed-pan experiments. The reaction clearly displays more than one process, and most likely three processes, which are most clearly evident in open pan experiments. The reaction is accelerated for closed pan experiments, and one global reaction fits the data fairly well. Our A-E values lie in the middle of the values given in a compensation-law plot by Brill et al. (1994). Comparison with additional open and closed low temperature pyrolysis experiments support an activation energy of 165 kJ/mol at 10% conversion.
Date: March 17, 2005
Creator: Burnham, A K & Weese, R K
Object Type: Article
System: The UNT Digital Library
Development and Applications of Time of Flight Neutron Depth Profiling (open access)

Development and Applications of Time of Flight Neutron Depth Profiling

The depth profiles of intentional or intrinsic constituents of a sample provide valuable information for the characterization of materials. For example, the subtle differences in spatial distribution and composition of many chemical species in the near surface region and across interfacial boundaries can significantly alter the electronic and optical properties of materials. A number of analytical techniques for depth profiling have been developed during the last two decades. neutron Depth Profiling (NDP) is one of the leading analytical techniques. The NDP is a nondestructive near surface technique that utilizes thermal/cold neutron beam to measure the concentration of specific light elements versus their depth in materials. The depth is obtained from the energy loss of protons, alphas or recoil atoms in substrate materials. Since the charged particle energy determination using surface barrier detector is used for NDP, the depth resolution is highly dependent on the detectors an d detection instruments. The depth resolutions of a few tens of nm are achieved with available NDP facilities in the world. However, the performance of NDP needs to be improved in order to obtain a few A depth resolutions.
Date: March 17, 2005
Creator: Cady, Bingham & Unlu, Kenan
Object Type: Report
System: The UNT Digital Library
Refinery Integration of By-Products from Coal-Derived Jet Fuels (open access)

Refinery Integration of By-Products from Coal-Derived Jet Fuels

This report summarizes the accomplishments toward project goals during the no cost extension period of the third year of the project to assess the properties and performance of coal based products. These products are in the gasoline, diesel and fuel oil range and result from coal based jet fuel production from an Air Force funded program. Specific areas of progress include generation of coal based material that has been fractionated into the desired refinery cuts for a third round of testing, the use of a research gasoline engine to test coal-based gasoline, and modification of diesel engines for use in evaluating diesel produced in the project. At the pilot scale, the hydrotreating process was modified to separate the heavy components from the LCO and RCO fractions before hydrotreating in order to improve the performance of the catalysts in further processing. Hydrotreating and hydrogenation of the product has been completed, and due to removal of material before processing, yield of the jet fuel fraction has decreased relative to an increase in the gasoline fraction. Characterization of the gasoline fuel indicates a dominance of single ring alkylcycloalkanes that have a low octane rating; however, blends containing these compounds do not have a …
Date: March 17, 2007
Creator: Clifford, Caroline E. Burgess; Boehman, Andre; Song, Chunshan; Miller, Bruce & Mitchell, Gareth
Object Type: Report
System: The UNT Digital Library
A White Paper Prepared for the OpenMP Architectural Review Board on DMPL: An OpenMP DLL Debugging Interface (open access)

A White Paper Prepared for the OpenMP Architectural Review Board on DMPL: An OpenMP DLL Debugging Interface

OpenMP is a widely adopted standard for threading directives across compiler implementations. The standard is very successful since it provides application writers with a simple, portable programming model for introducing shared memory parallelism into their codes. However, the standards do not address key issues for supporting that programming model in development tools such as debuggers. In this paper, we present DMPL, an OpenMP debugger interface that can be implemented as a dynamically loaded library. DMPL is currently being considered by the OpenMP Tools Committee as a mechanism to bridge the development tool gap in the OpenMP standard.
Date: March 17, 2004
Creator: Cownie, James; DelSignore, John, Jr.; de Supinski, Bronis R. & Warren, Karen
Object Type: Report
System: The UNT Digital Library

Field scale evaluation of biostimulation in the near source zone of the former S3 ponds at Oak Ridge

The primary objective of this report is to evaluate the rates and mechanisms of U(VI) reduction by microbial populations.
Date: March 17, 2004
Creator: Criddle, Craig; Fendorf, Scott; Brandt, Craig; Brooks, Scott; Hubbard, Susan; Williams, Ken et al.
Object Type: Presentation
System: The UNT Digital Library
On Optimal Bilinear Quadrilateral Meshes (open access)

On Optimal Bilinear Quadrilateral Meshes

The novelty of this work is in presenting interesting error properties of two types of asymptotically ''optimal'' quadrilateral meshes for bilinear approximation. The first type of mesh has an error equidistributing property where the maximum interpolation error is asymptotically the same over all elements. The second type has faster than expected ''super-convergence'' property for certain saddle-shaped data functions. The ''superconvergent'' mesh may be an order of magnitude more accurate than the error equidistributing mesh. Both types of mesh are generated by a coordinate transformation of a regular mesh of squares. The coordinate transformation is derived by interpreting the Hessian matrix of a data function as a metric tensor. The insights in this work may have application in mesh design near corner or point singularities.
Date: March 17, 2000
Creator: D'Azevedo, E
Object Type: Report
System: The UNT Digital Library
"Final Report for Grant No. DE-FG02-97ER62492 "Engineering Deinococcus radiodurans for Metal Remediation in Radioactive Mixed Waste Sites" (open access)

"Final Report for Grant No. DE-FG02-97ER62492 "Engineering Deinococcus radiodurans for Metal Remediation in Radioactive Mixed Waste Sites"

The groundwater and sediments of numerous U. S. Department of Energy (DOE) field sites are contaminated with mixtures of heavy metals (e.g., Hg, Cr, Pd) and radionuclides (e.g., U, Tc), as well as the fuel hydrocarbons benzene, toluene, ethylbenzene and xylenes (BTEX); chlorinated hydrocarbons, such as trichloroethylene (TCE); and polychlorinated biphenyls (PCBs). The remediation of such mixed wastes constitutes an immediate and complex waste management challenge for DOE, particularly in light of the costliness and limited efficacy of current physical and chemical strategies for treating mixed wastes. In situ bioremediation via natural microbial processes (e.g., metal reduction) remains a potent, potentially cost-effective approach to the reductive immobilization or detoxification of environmental contaminants. Seventy million cubic meters of soil and three trillion liters of groundwater have been contaminated by leaking radioactive waste generated in the United States during the Cold War. A cleanup technology is being developed based on the extremely radiation resistant bacterium Deinococcus radiodurans. Our recent isolation and characterization of D. radiodurans from a variety of DOE environments, including highly radioactive sediments beneath one of the leaking tanks (SX-108) at the Hanford Site in south-central Washington state, underscores the potential for this species to survive in such extreme environments. …
Date: March 17, 2005
Creator: Daly, Michael J.
Object Type: Report
System: The UNT Digital Library
Reduction of Oxidative Melt Loss of Aluminum and Its Alloys (open access)

Reduction of Oxidative Melt Loss of Aluminum and Its Alloys

This project led to an improved understanding of the mechanisms of dross formation. The microstructural evolution in industrial dross samples was determined. Results suggested that dross that forms in layers with structure and composition determined by the local magnesium concentration alone. This finding is supported by fundamental studies of molten metal surfaces. X-ray photoelectron spectroscopy data revealed that only magnesium segregates to the molten aluminum alloy surface and reacts to form a growing oxide layer. X-ray diffraction techniques that were using to investigate an oxidizing molten aluminum alloy surface confirmed for the first time that magnesium oxide is the initial crystalline phase that forms during metal oxidation. The analytical techniques developed in this project are now available to investigate other molten metal surfaces. Based on the improved understanding of dross initiation, formation and growth, technology was developed to minimize melt loss. The concept is based on covering the molten metal surface with a reusable physical barrier. Tests in a laboratory-scale reverberatory furnace confirmed the results of bench-scale tests. The main highlights of the work done include: A clear understanding of the kinetics of dross formation and the effect of different alloying elements on dross formation was obtained. It was determined …
Date: March 17, 2006
Creator: Das, Dr. Subodh K. & Ningileri, Shridas
Object Type: Report
System: The UNT Digital Library