Physics Commons^™

University Of Nevada, Las Vegas Advanced Accelerator Applications University Participation Program: Quarterly Report, Third Quarter (September To November 2001), Anthony Hechanova

Transmutation Research Program Reports (TRP)

This Quarterly Report is a primary deliverable from the University of Nevada, Las Vegas (UNLV) Advanced Accelerator Applications (AAA) University Participation Program (UPP) Director to the U.S. Department of Energy (DOE) as described in the UNLV AAA proposal and Statement of Work for the Third Quarter.

The UNLV AAA UPP Director implements the program’s administration using staff from the Harry Reid Center for Environmental Studies (HRC) to ensure that work conducted under the UNLV AAA UPP meets program objectives. The UNLV AAA UPP consists of three components: Program Support, Research Infrastructure Augmentation, and Student Research.

Nuclear Criticality Analyses Of Separations Processes For The Transmutation Fuel Cycle: Quaterly Report, William Culbreth, Pang Tao

Separations Campaign (TRP)

During the first quarter of the work, the tasks included training students in the use of Monte Carlo codes used in radiation transport studies and the assessment of neutron multiplication factors for specific problems outlined by ANL-East through Drs. Laidler and Vandegrift.

The proposal also included objectives for the first year of work on this project, as listed below. The work conducted in the first quarter of the project was in partial completion of these objectives.

• Train UNLV students in the use of SCALE and/or MCNP for the assessment of nuclear criticality.

• Assess neutron multiplication factor, k_{eff …}

Radiation Transport Modeling Of Beam-Target Experiments For The Aaa Project: Quaterly Report, William Culbreth

Reactor Campaign (TRP)

The national development of technology to transmute nuclear waste depends upon the generation of high energy neutrons produced by proton spallation. Proton accelerators, such as LANSCE at the Los Alamos National Laboratory, are capable of producing 800 MeV protons. By bombarding a lead/bismuth target, each proton may generate 500 or more neutrons that can activate fission products or induce the fission of transuranic isotopes.

The Monte Carlo radiation transport code MCNPX developed at LANL is an important tool in the design of transmuter technology. It must be validated, however, for the neutron energy that will be employed. Experiments are being …

Techniques For The Regeneration Of Wideband Speech From Narrowband Speech, Jason A. Fuemmeler, Russell C. Hardie, William R. Gardner

Electrical and Computer Engineering Faculty Publications

This paper addresses the problem of reconstructing wideband speech signals from observed narrowband speech signals. The goal of this work is to improve the perceived quality of speech signals which have been transmitted through narrowband channels or degraded during acquisition. We describe a system, based on linear predictive coding, for estimating wideband speech from narrowband. This system employs both previously identified and novel techniques. Experimental results are provided in order to illustrate the system’s ability to improve speech quality. Both objective and subjective criteria are used to evaluate the quality of the processed speech signals.

Design And Evaluation Of Processes For Fuel Fabrication: Quarterly Progress Report #1, Georg F. Mauer

Fuels Campaign (TRP)

The first three months of the project covered the following:

• Literature review: A comprehensive study of the pertinent publications pertaining to transmuter fuels composition and manufacturing processes was conducted.

• Visit at ANL West in Idaho Falls, ID: Dr. Mauer visited the ANL West facility and met with his National Laboratory Collaborator, Dr. Mitchell K. Meyer, Group Leader, Fabrication Development on October 14 and 15, 2001.

• Student Paper Presentation at the ANS Annual Meeting by Ph.D. student Mr. Jae-Kyu Lee. Title: Transmuter Fuel Fabrication Processes.

Analysis Of Corrosion Of Steel By Lead Bismuth Eutectic, John Farley, Dale L. Perry

Transmutation Sciences Materials (TRP)

We examined stainless samples that were exposed to LBE in experiments conducted by the Russians, under contract to Los Alamos. We examined both corroded and uncorroded samples using the Scanning Electron Microscope (SEM), the Energy Dispersive X-Ray (EDAX) Spectroscopy, and the X-ray Photoelectron Spectrometer (XPS). We found that the surface of the corroded sample is covered by oxygen-containing compounds, presumably mostly iron oxide. In samples exposed for shorter times or lower temperatures, we found that some areas were covered by an oxide layer, and some areas was uncovered. We found that the level of Cr in the uncovered area is …

Design And Analysis For Melt Casting Metallic Fuel Pins Incorporating Volatile Actinides: Quarterly Progress Report 8/16/01- 11/15/01, Yitung Chen, Randy Clarksean, Darrell Pepper

Fuels Campaign (TRP)

An important aspect of the Advanced Accelerator Applications (AAA) program is the development of a casting process by which volatile actinide element (i.e., americium) can be incorporated into metallic alloy fuel pins. The traditional metal fuel casting process uses an inductively heated crucible. The process involves evacuation of the furnace. The evacuation of the furnace also evacuates quartz rods used as fuel pin molds. Once evacuated the open ends of the molds are lowered into the melt; the casting furnace is then rapidly pressurized, forcing the molten metal up into the evacuated molds where solidification occurs.

This process works well …

Capillary Flow In Interior Corners: The Infinite Column, Mark M. Weislogel

Mechanical and Materials Engineering Faculty Publications and Presentations

Capillary flow of a sinusoidally perturbed liquid column in an interior corner of infinite extent is solved using lubrication theory. Due primarily to the length scales selected to nondimensionalize the momentum equation, an analytic time scale governing the settling of the perturbation is determined. The time scale, which is shown to be independent of a steady base state flow, proves useful in rapidly predicting transients for surface settling in certain liquid-bearing tanks of spacecraft employing interior corners for fluids management purposes. The asymptotic analysis is extended to address flows along interior corners whose faces are slightly nonplanar. The generalized formulation …

Assessment Of Criticality Safety For Cylindrical Containers To Be Used In The Processing Of Spent Fuel, William Culbreth, Daniel R. Lowe, Jason Viggato

Separations Campaign (TRP)

The UREX process separates uranium from transuranic wastes (TRU) and fission products (FP). Nuclear reactors require fissile isotopes that will absorb neutrons and break apart into smaller nuclei while releasing a large amount of energy as well as multiple neutrons. Fissile isotopes in spent fuel include not only ²³⁵U, but also ²³⁹Pu, ²⁴¹Pu, and several isotopes of americium (Am) and curium (Cm).

TRU contains the actinides with atomic numbers greater than that of uranium. This includes Pu, Np, Am, and Cm. When TRU is separated from uranium, the TRU still poses a significant risk of sustaining a …

University Of Nevada, Las Vegas Advanced Accelerator Applications University Participation Program: Quarterly Report, Second Quarter (June To August 2001), Anthony Hechanova

Transmutation Research Program Reports (TRP)

This Quarterly Report is a primary deliverable from the University of Nevada, Las Vegas (UNLV) Advanced Accelerator Applications (AAA) University Participation Program (UPP) Director to the U.S. Department of Energy (DOE) as described in the UNLV AAA proposal.

The UNLV AAA UPP Director implements the program’s administration using staff from the Harry Reid Center for Environmental Studies (HRC) to ensure that work conducted under the UNLV AAA UPP meets program objectives. The UNLV AAA UPP consists of three components: Program Administration, Research Infrastructure Augmentation, and Student Research.

On Misorientation Distribution Evolution During Anisotropic Grain Growth, Elizabeth A. Holm, Gregory N. Hassold, Mark A. Miodownik

Physics Publications

In order to study the development of texture and boundary character during annealing, three-dimensional grain crystallography and crystallographically mediated grain boundary properties were incorporated into a finite temperature Monte Carlo model for grain growth. Randomly textured microstructures evolve normally, with growth exponent n=0.96. While texture remains random, the steady-state boundary misorientation distribution favors low-angle boundaries. To first order, low-angle boundaries increase by lengthening, not by proliferating. In contrast, microstructures with a strong single-component texture develop four-grain junctions and highly curved grain boundaries, which alter evolution. The boundary misorientation distribution narrows and shifts to low angles, and no steady state …

Design And Analysis For Melt Casting Metallic Fuel Pins Incorporating Volatile Actinides: Quarterly Report 5/15/01-8/15/01, Yitung Chen, Darrell Pepper, Randy Clarksean

Fuels Campaign (TRP)

No abstract provided.

Analysis Of Corrosion Of Steel By Lead Bismuth Eutectic, John Farley, Dale L. Perry

Transmutation Sciences Materials (TRP)

The goal is to achieve a basic understanding of the corrosion of stainless steel by Lead Bismuth Eutectic (LBE), which has been proposed for use in the transmuter as both a coolant and as a sputtering target.

Nuclear Criticality Analyses Of Separations Processes For The Transmutation Fuel Cycle, William Culbreth, Pang Tao

Separations Campaign (TRP)

To mitigate the waste created by conventional fission reactors, spent nuclear fuel must be mechanically separated from its cladding. For the development of fuel processing technology to support the Advanced Accelerator Applications (AAA) Program, aqueous and pyrochemical processes will be used to further separate technetium and iodine, uranium and the higher actinides (see Figure 1 for an example of the process layout)1. The higher actinides, including plutonium, americium, curium, and neptunium will be separated from the waste to facilitate their fabrication into new fuel for placement in a transmuter. High-energy neutrons generated by spallation in the transmuter break down these …

Radiation Transport Modeling Of Beam-Target Experiments For The Aaa Project, William Culbreth

Reactor Campaign (TRP)

The AAA program will rely on the use of an accelerator-based transmuter to expose spent nuclear fuel to high-energy neutrons. The neutron flux will be sufficient to activate or fission the long-lived isotopes of Tc, I, Pu, Am, Cm, and Np that present a significant safety hazard in commercial spent fuel. Transmuter fuel will be subcritical and a high-energy proton accelerator is needed to maintain the necessary neutron flux through the use of a neutron spallation target. The maximum neutron energy produced by spallation (~ 600 MeV) is significantly higher than that produced by a commercial light water reactor (~ …

Design And Evaluation Of Processes For Fuel Fabrication, Georg F. Mauer

Fuels Campaign (TRP)

The objective of this project is the design and evaluation of manufacturing processes for transmuter fuel fabrication. A detailed design description for the manufacturing of each candidate fuel type would support the informed selection of fuel for a transmutation system. We will collect pertinent manufacturing and process-related information and create an information database that will document the design, operations, and cost implications of various fuel choices. Fabrication processes for different fuel types will likely differ in terms of equipment types, throughput, and cost.

Year 1 of the project will be devoted to the analysis and assessment of the multiple steps …

University Of Nevada, Las Vegas Advanced Accelerator Applications University Participation Program: Quarterly Report First Quarter (March-May 2001), Anthony Hechanova

Transmutation Research Program Reports (TRP)

This Quarterly Report is a primary deliverable from the University of Nevada, Las Vegas (UNLV) Advanced Accelerator Applications (AAA) University Participation Program (UPP) director to the U.S. Department of Energy Office of Nuclear Energy, Science and Technology (DOE-NE) as defined in the UNLV AAA Proposal.

The foundation of the UNLV AAA University Participation Program started as a grassroots effort in the late 1990s among community members and local, state, and federal representatives to encourage research and development of technical alternatives to direct disposal of used nuclear fuel which had been targeted since the early 1980s for Yucca Mountain, Nevada. A …

Microcavity Surface Emitting Laser, Stewart Feld, John P. Loehr, James A. Lott

AFIT Patents

A three-dimensional waveguiding structure for a microcavity surface-emitting laser is described in which native aluminum oxide layers provide control of intracavity waveguiding and the laser optical mode structure of the emitted beam. Microcavity lasers described herein account for the blueshift of the emission wavelength as the laser lateral dimensions are reduced to or below the emission wavelength.

Feedback Correction Of Angular Error In Grating Readout, Monish Ranjan Chatterjee, Sundaram Ramachandran

Electrical and Computer Engineering Faculty Publications

Angular and wavelength READ beam errors in holographic interconnection systems are often a recurrent problem. Several strategies have been proposed to minimize or eliminate such READOUT misalignments.

Some years ago, Chatterjee and co-workers proposed a method involving READ beam wavelength tuning to correct output angular errors. In this paper, we investigate the possibility of using an acousto-optic (A-O) Bragg cell with optoelectronic feedback to dynamically correct the scattered beam for deviations in the incidence direction of the READ beam of a hologram. The concept here is based on an acoustic frequency feedback strategy used recently by Balakshy and Kazaryan for …

Overview Of Acousto-Optic Bistability, Chaos, And Logical Applications, Monish Ranjan Chatterjee, Erol Sonmez

Electrical and Computer Engineering Faculty Publications

An overview is presented of the key results in the field of acousto-optic bistability in the past two decades. It is shown that the basic acousto-optic bistable device may be described as a nonlinear dynamical system which satisfies a quadratic map. Thereafter, details are presented of several analytical methods, computer modeling approaches, including the SPICE circuit modeling technique, and experiments that have been used to understand the phenomenon.

Extensions to logical and digital applications are also discussed.

Design And Analysis For Melt Casting Metallic Fuel Pins Incorporating Volatile Actinides, Yitung Chen, Darrell Pepper, Randy Clarksean

Fuels Campaign (TRP)

UNLV investigators will evaluate and select a process for the melt casting of metallic fuel pins that contain volatile actinides. This work will be performed with the guidance of Argonne National Laboratory (ANL) engineers to insure that their knowledge and experience benefits the project. The research to be conducted during year one will center on selecting, evaluating, and modeling potential alternatives to the traditional injection casting process used at ANL. Processing conditions will be analyzed, basic models utilized, and detailed heat and mass transfer models will be developed to analyze the most promising processes. The goal of the first year …

Effects Of Concentration And Temperature On The Coupled Heat And Mass Transport In Liquid Mixtures, Yaşar Demirel, Stanley I. Sandler

Papers in Thermal Mechanics

Using published experimental data on the thermal conductivity, mutual diffusivity, and heats of transport, the degree of coupling between heat and mass flows has been calculated for binary and ternary nonideal liquid mixtures. The binary mixtures consist of two types: the first is six systems of six-to-eight-carbon straight and branched chain alkanes in chloroform and in carbon tetrachloride; and the second is mixtures of carbon tetrachloride with benzene, toluene, 2-propanone, n-hexane, and 11-octane. The ternary mixture considered is toluene-chlorobenzene-bromobenzene. The published data are available at 35°C, 30°C, and 35°C and ambient pressure. Using the linear nonequilibi-ium thermodynainics (LNET) and the …

Bistable Operation Of A Two-Section 1.3-Mm Inas Quantum Dot Laser—Absorption Saturation And The Quantum Confined Stark Effect, Xiaodong Huang, A. Stintz, Hua Li, Audra Rice, G. T. Liu, L.F. Lester, Julian Cheng, K.J. Malloy

Faculty Publications

Room temperature, continuous-wave bistability was observed in oxide-confined, two-section, 1.3- m quantum-dot (QD) lasers with an integrated intracavity quantum-dot saturable absorber. The origin of the hysteresis and bistability were shown to be due to the nonlinear saturation of the QD absorption and the electroabsorption induced by the quantum confined Stark effect.

Tilted Bilayer Membranes As Simple Transmission Quarter-Wave Retardation Plates, R. M.A. Azzam, Fadi A. Mahmoud

Electrical Engineering Faculty Publications

A tilted bilayer membrane, which consists of two thin films of transparent optically isotropic materials of different refractive indices, can function as a transmission quarter-wave retarder (QWR) at a high angle of incidence. A specific design using a cryolite-Si membrane in the infrared is presented, and its tolerances to small shifts of wavelength, incidence angle, and film thickness errors are discussed. Some designs provide a dual QWR in transmission and reflection. Such devices provide simple linear-to-circular (and circular-to-linear) polarization transformers. Bilayer eighth-wave retarders without diattenuation are also introduced.

Experimental Investigation Of Steel Corrosion In Lead Bismuth Eutectic (Lbe): Characterization, Species Identification, And Chemical Reactions, John Farley, Dale L. Perry

Transmutation Sciences Materials (TRP)

The goal of the present research is to achieve a basic understanding of corrosion of steels by Lead Bismuth Eutectic (LBE). Liquid LBE is under consideration in the transmuter as both a coolant and a target material. There have been studies of LBE, especially by the Russians, but a fundamental understanding and verification of its role in the corrosion of steels is still very 2 incomplete. Post-experiment testing and analysis will be performed on steel samples that have been in intimate contact with LBE. Chemical alterations and resulting chemical species will be measured at the steel surface. Techniques to be …

Xenon Excimer Emission From Pulsed Microhollow Cathode Discharges, M. Moselhy, R. H. Stark, K. H. Schoenbach, U. Kogelschatz

Bioelectrics Publications

By applying electrical pulses of 20 ns duration to xenon microplasmas, generated by direct current microhollow cathode discharges, we were able to increase the xenon excimer emission by more than an order of magnitude over direct current discharge excimer emission. For pulsed voltages in excess of 500 V, the optical power at 172 nm was found to increase exponentially with voltage. Largest values obtained were 2.75 W of vacuum-ultraviolet optical power emitted from a single microhollow cathode discharge in 400 Torr xenon with a 750 V pulse applied to a discharge. Highest radiative emittance was 15.2 W/cm². The …

Entropy Generation Method To Quantify Thermal Comfort, S. C. Boregowda, S. N. Tiwari, S. K. Chaturvedi

Mechanical & Aerospace Engineering Faculty Publications

The present paper presents a thermodynamic approach to assess the quality of human-thermal environment interaction and quantify thermal comfort. The approach involves development of entropy generation term by applying second law of thermodynamics to the combined human-environment system. The entropy generation term combines both human thermal physiological responses and thermal environmental variables to provide an objective measure of thermal comfort. The original concepts and definitions form the basis for establishing the mathematical relationship between thermal comfort and entropy generation term. As a result of logic and deterministic approach, an Objective Thermal Comfort Index (OTCI) is defined and established as a …

Eddy Structures Induced Within A Wedge By A Honing Circular Arc, C. P. Hills

Articles

In this paper we outline an expeditious numerical procedure to calculate the Stokes flow in a corner due to the rotation of a scraping circular boundary. The method is also applicable to other wedge geometries. We employ a collocation technique utilising a basis of eddy (similarity) functions introduced by Moffatt (1964) that allows us to satisfy automatically the governing equations for the streamfunction and all the boundary conditions on the surface of the wedge. The circular honing problem thereby becomes one-dimensional requiring only the satisfaction of conditions on the circular boundary. The advantage of using the Moffatt eddy functions as …

Eddies Induced In Cylindrical Containers By A Rotating End Wall, Christopher Hills

Articles

The flow generated in a viscous liquid contained in a cylindrical geometry by a rotating end wall is considered. Recent numerical and experimental work has established several distinct phases of the motion when fluid inertia plays a significant role. The current paper, however, establishes the nature of the flow in the thus far neglected low Reynolds number regime. Explicitly, by employing biorthogonality relations appropriate to the current geometry, it is shown that a sequence of exponentially decaying eddies extends outward from the rotating end wall. The cellular structure is a manifestation of the dominance of complex eigensolutions to the homogeneous …

A New Compensating Element For A Femtosecond Photoelectron Gun, Bao-Liang Qian, Hani E. Elsayed-Ali

Electrical & Computer Engineering Faculty Publications

Design and analysis of a new compensating element for improving the electron pulse front and compressing the pulse duration in a femtosecond photoelectron gun are described. The compensating element is a small metallic cylindrical cavity in which an external voltage is applied in such a way that a special electric field forms and interacts with the electron pulse. This electric field reduces the distances between the faster and slower electrons inside the cavity and efficiently compensates for electron pulse broadening caused by the photoelectron energy spread and space charge effects. Poisson's equation and the equation of motion are solved to …