Rheological Studies on Pretreated Feed and Melter Feed from AW-101 and AN-107 (open access)

Rheological Studies on Pretreated Feed and Melter Feed from AW-101 and AN-107

Rheological and physical properties testing were conducted on actual AN-107 and AW-101 pretreated feed samples prior to the addition of glass formers. Analyses were repeated following the addition of glass formers. The AN-107 and AW-101 pretreated feeds were tested at the target sodium values of nominally 6, 8, and 10 M. The AW-101 melter feeds were tested at these same concentrations, while the AN-107 melter feeds were tested at 5, 6, and 8 M with respect to sodium. These data on actual waste are required to validate and qualify results obtained with simulants.
Date: February 6, 2001
Creator: Bredt, Paul R. (BATTELLE (PACIFIC NW LAB)) & Swoboda, Robert G. (BATTELLE (PACIFIC NW LAB))
Object Type: Report
System: The UNT Digital Library
Shock Compression of Hydrogen and Other Small Molecules (open access)

Shock Compression of Hydrogen and Other Small Molecules

None
Date: July 6, 2001
Creator: Nellis, W J
Object Type: Article
System: The UNT Digital Library
Metastable metallic hydrogen glass (open access)

Metastable metallic hydrogen glass

The quest for metallic hydrogen has been going on for over one hundred years. Before hydrogen was first condensed into a liquid in 1898, it was commonly thought that condensed hydrogen would be a metal, like the monatomic alkali metals below hydrogen in the first column of the Periodic Table. Instead, condensed hydrogen turned out to be transparent, like the diatomic insulating halogens in the seventh column of the Periodic Table. Wigner and Huntington predicted in 1935 that solid hydrogen at 0 K would undergo a first-order phase transition from a diatomic to a monatomic crystallographically ordered solid at {approx}25 GPa. This first-order transition would be accompanied by an insulator-metal transition. Though searched for extensively, a first-order transition from an ordered diatomic insulator to a monatomic metal is yet to be observed at pressures up to 120 and 340 GPa using x-ray diffraction and visual inspection, respectively. On the other hand, hydrogen reaches the minimum electrical conductivity of a metal at 140 GPa, 0.6 g/cm{sup 3}, and 3000 K. These conditions were achieved using a shock wave reverberating between two stiff sapphire anvils. The shock wave was generated with a two-stage light-gas gun. This temperature exceeds the calculated melting temperature …
Date: February 6, 2001
Creator: Nellis, W J
Object Type: Article
System: The UNT Digital Library
Relative Advantages of Direct and Indirect Drive for an Inertial Fusion Energy Power Plant Driven by a Diode-Pumped Solid-State Laser (open access)

Relative Advantages of Direct and Indirect Drive for an Inertial Fusion Energy Power Plant Driven by a Diode-Pumped Solid-State Laser

This paper reviews our current understanding of the relative advantages of direct drive (DD) and indirect drive (ID) for a 1 GWe inertial fusion energy (IFE) power plant driven by a diode-pumped solid-state laser (DPSSL). This comparison is motivated by a recent study (1) that shows that the projected cost of electricity (COE) for DD is actually about the same as that for ID even though the target gain for DD can be much larger. We can therefore no longer assume that DD is the ultimate targeting scenario for IFE, and must begin a more rigorous comparison of these two drive options. The comparison begun here shows that ID may actually end up being preferred, but the uncertainties are still rather large.
Date: March 6, 2001
Creator: Orth, C D
Object Type: Article
System: The UNT Digital Library
Inertial Fusion and High-Energy-Density Science in the United States (open access)

Inertial Fusion and High-Energy-Density Science in the United States

Inertial fusion and high-energy density science worldwide is poised to take a great leap forward. In the US, programs at the University of Rochester, Sandia National Laboratories, Los Alamos National Laboratory, Lawrence Livermore National Laboratory (LLNL), the Naval Research Laboratory, and many smaller laboratories have laid the groundwork for building a facility in which fusion ignition can be studied in the laboratory for the first time. The National Ignition Facility (NIF) is being built by the Department of Energy's National Nuclear Security Agency to provide an experimental test bed for the US Stockpile Stewardship Program (SSP) to ensure the dependability of the country's nuclear deterrent without underground nuclear testing. NIF and other large laser systems being planned such as the Laser MegaJoule (LMJ) in France will also make important contributions to basic science, the development of inertial fusion energy, and other scientific and technological endeavors. NIF will be able to produce extreme temperatures and pressures in matter. This will allow simulating astrophysical phenomena (on a tiny scale) and measuring the equation of state of material under conditions that exist in planetary cores.
Date: September 6, 2001
Creator: Tarter, C B
Object Type: Article
System: The UNT Digital Library
Simulation of Edge Plasmas in DIII-D Double-Null Configurations (open access)

Simulation of Edge Plasmas in DIII-D Double-Null Configurations

We present fluid model simulation results for the edge plasma in the DIII-D tokamak with unbalanced double-null magnetic configurations, including cross field drifts. Input parameters are typical of low-power operation in DIII-D. For high-recycling the plasma tends to be detached from all divertor plates. Midplane plasma and electric field profiles are relatively insensitive to the magnetic imbalance. Divertor heat flux profiles exhibit sharp peaks due to cross-field drifts when the ion grad-B drift direction is away from the x-point toward the magnetic axis.
Date: September 6, 2001
Creator: Rensink, M. E.; Lasnier, C. J.; Petrie, T. W.; Porter, G. D. & Rognlien, T D
Object Type: Article
System: The UNT Digital Library
Mapping of Enhanced Nuclear Stability in the Heaviest Elements (open access)

Mapping of Enhanced Nuclear Stability in the Heaviest Elements

Predictions of the properties of nuclides near the extreme limits of nuclear stability provide a measure of our understanding of the fundamental properties of matter and the fission process. Predictions of an ''island of stability'' of long-lived superheavy elements beyond the limits of the known nuclides date back more than 30 years; during this time, there have been many unsuccessful searches for these nuclei. During the last decade, there has been a large effort by our group and others to systematically discover and characterize the properties of the intervening unstable nuclei. Starting 10 years ago, in an on-going collaboration with Russian scientists at the Joint Institute for Nuclear Research (JINR) at Dubna, Russia, we observed the decays of previously unknown isotopes of elements 106, 108, and 110 whose properties are determined by subtleties in the nuclear structure caused by the shell effects that are predicted to result in the island of stability in the still-heavier elements. The resulting data have been successfully reproduced by the theoreticians, whose refined predictions of the decay modes and production rates of the superheavy elements have enabled us to design experiments with the sensitivity to locate these elusive nuclides.
Date: March 6, 2001
Creator: Moody, K J; Wild, J F; Stoyer, N J; Stoyer, M A; Laue, C A & Lougheed, R W
Object Type: Report
System: The UNT Digital Library
Seismic Safety Analysis of Heavy Element Facility at Lawrence Livermore National Laboratory (open access)

Seismic Safety Analysis of Heavy Element Facility at Lawrence Livermore National Laboratory

The Heavy Element Facility is a cold war legacy facility at Livermore National Laboratory. The facility's mission has varied over its lifetime, but operations included the preparation of radioactive heavy element tracers used in underground nuclear weapons testing and the conduct of a heavy element research program. It is a one story concrete masonry structure constructed in several phases between 1955 and 1981. In 1993, a seismic re-evaluation of the facility determined that portions of the building did not meet the PC-2 requirements applicable to it. A seismic upgrade evaluation determined it was not practical to upgrade the facility to support continued programmatic operations. It is now maintained in a storage mode awaiting Department of Energy disposition. In this mode the operations are limited to (1) storage of radioactive material from previous operations, (2) clean-up and decontamination of facility work areas and equipment, (3) removal of contaminated systems and enclosures, (4) facility maintenance, (5) removal of radioactive materials from the facility, (6) characterization of the waste generated by these activities, (7) surveillance activities and (8) security. An important part of the facility's storage function is provided by underground storage vaults. These are embedded in a massive reinforced concrete block whose …
Date: June 6, 2001
Creator: O'Connell, W J & S, Hildum J
Object Type: Article
System: The UNT Digital Library
Immobilization of AM-241, Formed Under Plutonium Metal Conversion into Monazite-Type Ceramics (open access)

Immobilization of AM-241, Formed Under Plutonium Metal Conversion into Monazite-Type Ceramics

Lanthanum orthophosphate with the monazite structure was proposed on examinations as a suitable matrix for immobilization of future americium-containing liquid wastes, which could be formed in conversion of metallic plutonium into oxide at PA ''Mayak.'' Specimens of monazite non-active ceramics were fabricated from LaPOA powders obtained using a thin-film evaporator by either hot-pressing or cold-pressing and sintering at 900-1300 C. According to electron microprobe analysis (EMPA), scanning electron microscopy (SEM), and X-ray diffraction (XRD), which were used for characterization of produced samples, all specimens did not contain any phase other than the monoclinic monazite phase. Ceramics having the specific activity of Am-241 2.13 {center_dot}10{sup 7} Bq/g were prepared by only cold-pressing with subsequent sintering at 1300 C during 1 hour. The normalized leach rates of lanthanum and americium in distilled water at 90 C were less than 1.2. 10{sup 4} and 2.3 10{sup -4} g/m{sup 2} {center_dot} day, respectively.
Date: June 6, 2001
Creator: Aloy, A. S.; Kovarskaya, E. N.; Koltsova, T. I.; Samoylov, S. E.; Rovnyi, S. I.; Medvedev, G. M. et al.
Object Type: Article
System: The UNT Digital Library
Higher-Order Semi-Implicit Projection Methods (open access)

Higher-Order Semi-Implicit Projection Methods

A semi-implicit form of the method of spectral deferred corrections is applied to the solution of the incompressible Navier-Stokes equations. A methodology for constructing semi-implicit projection methods with arbitrarily high order of temporal accuracy in both the velocity and pressure is presented. Three variations of projection methods are discussed which differ in the manner in which the auxiliary velocity and the pressure are calculated. The presentation will make clear that project methods in general need not be viewed as fractional step methods as is often the practice. Two simple numerical examples re used to demonstrate fourth-order accuracy in time for an implementation of each variation of projection method.
Date: September 6, 2001
Creator: Minion, M. L.
Object Type: Article
System: The UNT Digital Library
Low-Temperature Technology and Physical Processes in Green Thin-Film Phosphor Zn2GeO4-Mn (open access)

Low-Temperature Technology and Physical Processes in Green Thin-Film Phosphor Zn2GeO4-Mn

Thin-film Zn{sub 2}GeO{sub 4}:Mn phosphors with lower temperature of crystallization, and potentially compatible with industrial technologies were investigated. The technology of thin films synthesis has been developed, as well as their structure and crystal parameters have been investigated. Photoluminescence excitation spectra, photoconductivity, temperature dependencies and ESR-spectra determined by manganese ions were studied. The mechanism of luminescence in this phosphor has been proposed. Cathodo- and electroluminescent parameters of thin film structures based on Zn{sub 2}GeO{sub 4}:Mn are presented.
Date: May 6, 2001
Creator: Bondar, V.; Popovich, S.; Felter, T. & Wager, J.
Object Type: Article
System: The UNT Digital Library
Speech Articulator and User Gesture Measurements Using Micropower, Interferometric EM-Sensors (open access)

Speech Articulator and User Gesture Measurements Using Micropower, Interferometric EM-Sensors

Very low power, GHz frequency, ''radar-like'' sensors can measure a variety of motions produced by a human user of machine interface devices. These data can be obtained ''at a distance'' and can measure ''hidden'' structures. Measurements range from acoustic induced, 10-micron amplitude vibrations of vocal tract tissues, to few centimeter human speech articulator motions, to meter-class motions of the head, hands, or entire body. These EM sensors measure ''fringe motions'' as reflected EM waves are mixed with a local (homodyne) reference wave. These data, when processed using models of the system being measured, provide real time states of interface positions or other targets vs. time. An example is speech articulator positions vs. time in the user's body. This information appears to be useful for a surprisingly wide range of applications ranging from speech coding synthesis and recognition, speaker or object identification, noise cancellation, hand or head motions for cursor direction, and other applications.
Date: February 6, 2001
Creator: Holzrichter, J F & Ng, L C
Object Type: Article
System: The UNT Digital Library
Explosion-induced combustion of hydrocarbon clouds in a chamber (open access)

Explosion-induced combustion of hydrocarbon clouds in a chamber

The interaction of the detonation of a solid HE-charge with a non-premixed cloud of hydro-carbon fuel in a chamber was studied in laboratory experiments. Soap bubbles filled with a flammable gas were subjected to the blast wave created by the detonation of PETN-charges (0.2 g < mass < 0.5 g). The dynamics of the combustion system were investigated by means of high-speed photography and measurement of the quasi-static chamber pressure.
Date: February 6, 2001
Creator: Neuwald, P; Reichenbach, H & Kuhl, A L
Object Type: Article
System: The UNT Digital Library
Simulations of shock-induced mixing& combustion of an acetylene cloud in a chamber (open access)

Simulations of shock-induced mixing& combustion of an acetylene cloud in a chamber

In this paper we present numerical simulations of the interaction of a blast wave with an acetylene bubble in a closed chamber. We model the system using the inviscid Euler equations for a mixture of ideal gases. The formulation specifies the thermodynamic behavior of the system using a Chemkin interface and includes the capability to model combustion as the ambient air mixes with the acetylene. The simulations are performed using a three-dimensional adaptive mesh refinement algorithm based on a second-order Godunov integration scheme. Simulations are compared with experimental measurements for the same configuration.
Date: February 6, 2001
Creator: Bell, J B; Day, M S; Beckner, V E; Kuhl, A L; Neuwald, P & Reichenbach, H
Object Type: Article
System: The UNT Digital Library
Mixing-controlled exothermic fields in explosions (open access)

Mixing-controlled exothermic fields in explosions

A theoretical model of combustion in explosions at large Reynolds, Peclet and Damkoehler numbers is described. A key feature of the model is that combustion is treated as material transformations in the Le Chatelier state plane, rather than ''heat release''. In the limit considered here, combustion is concentrated on thin exothermic sheets (boundaries between fuel and oxidizer). The products seem to expand along the sheet, thereby inducing vorticity on either side of the sheet that continues to feed the process. The results illustrate the linking between turbulence (vorticity) and exothermicity (dilatation) in the limit of fast chemistry--thereby demonstrating the controlling role that fluid dynamics plays in such problems.
Date: February 6, 2001
Creator: Kuhl, A L; Oppenheim, A K & Ferguson, R E
Object Type: Article
System: The UNT Digital Library
Novel Parallel Numerical Methods for Radiation& Neutron Transport (open access)

Novel Parallel Numerical Methods for Radiation& Neutron Transport

In many of the multiphysics simulations performed at LLNL, transport calculations can take up 30 to 50% of the total run time. If Monte Carlo methods are used, the percentage can be as high as 80%. Thus, a significant core competence in the formulation, software implementation, and solution of the numerical problems arising in transport modeling is essential to Laboratory and DOE research. In this project, we worked on developing scalable solution methods for the equations that model the transport of photons and neutrons through materials. Our goal was to reduce the transport solve time in these simulations by means of more advanced numerical methods and their parallel implementations. These methods must be scalable, that is, the time to solution must remain constant as the problem size grows and additional computer resources are used. For iterative methods, scalability requires that (1) the number of iterations to reach convergence is independent of problem size, and (2) that the computational cost grows linearly with problem size. We focused on deterministic approaches to transport, building on our earlier work in which we performed a new, detailed analysis of some existing transport methods and developed new approaches. The Boltzmann equation (the underlying equation to …
Date: March 6, 2001
Creator: Brown, P N
Object Type: Report
System: The UNT Digital Library
Numerical Modeling of Left-Handed Metamaterials (open access)

Numerical Modeling of Left-Handed Metamaterials

The EIGER method of moments program with periodic Green's function was used to model a periodic array of strips and split-ring resonators. Left-handed propagation due to negative index of refraction is demonstrated in a frequency band. The effective material parameters versus frequency are extracted from the EIGER solution.
Date: November 6, 2001
Creator: Burke, G J; Champagne, N J & Sharpe, R M
Object Type: Article
System: The UNT Digital Library
Identification and Elimination of Mechanisms Leading to UV Damage of DKDP (open access)

Identification and Elimination of Mechanisms Leading to UV Damage of DKDP

This LDRD project addressed both bulk and surface damage induced by UV-laser exposure. The primary objectives were (1) to complete our understanding of the factors leading to bulk damage, including growth conditions and orientational direction, and (2) to identify mechanisms of surface damage initiation and growth leading to mitigation methods. Due to the more advanced state of knowledge in bulk damage, a greater portion of that work was completed during the one-year term of this project. Three papers were presented at the 32nd Boulder Damage Symposium on Laser-Induced Damage in Optical Materials, and the three resulting manuscripts submitted to the Proceeding are attached: An important result from this work is that it established a dependence of obscuration from bulk damage on fluence and pulse length, which is shown.
Date: March 6, 2001
Creator: Burnham, A; Runkel, M; Chase, L; Demos, S; Staggs, M & Siekhaus, W
Object Type: Report
System: The UNT Digital Library
Rock Physics Interpretation of P-Wave Q and Velocity Structure, Geology, Fluids and Fractures at the Southeast Portion of The Geysers Geothermal Reservoir (open access)

Rock Physics Interpretation of P-Wave Q and Velocity Structure, Geology, Fluids and Fractures at the Southeast Portion of The Geysers Geothermal Reservoir

We examine how quantitative rock physics models, such as effective medium theories, can improve the interpretation of seismic parameters and material and fluid properties at The Geysers. We use effective medium theories to estimate effects of fractures on velocities for The Geysers rocks. We compare theoretical velocity estimates to laboratory measurements from the literature and our seismic velocity values from 1992 earthquake data. We approximate the reservoir as being homogeneous in mineral composition, with a constant density of fractures whose total void ratio is reduced by lithostatic pressure. Thus, we expect low velocities near the surface, increasing with depth up to the values observed in the lab on intact samples, 5.5 - 5.7 km/sec. We use a one-dimensional inversion of P-waves to obtain an ''expected'' P-wave velocity (Vp) and attenuation (Qp) relation as a function of depth for The Geysers rocks. We then use a three-dimensional Vp and Qp inversion to find anomalous zones within the reservoir. We find portions with ''high'' Vp and Qp, high Vp and low Qp, and low Vp and low Qp. We interpret the regions with high Vp and Qp to be relatively less fractured, and the regions with low Vp and Qp to be …
Date: April 6, 2001
Creator: Berge, P; Hutchings, L; Wagoner, J & Kasameyer, P
Object Type: Article
System: The UNT Digital Library
Long-Term Cathodoluminescent Characterization of Thin-Film Oxide Phosphors in a Wide Range of Electron Excitation Densities (open access)

Long-Term Cathodoluminescent Characterization of Thin-Film Oxide Phosphors in a Wide Range of Electron Excitation Densities

Long-term processes of cathodoluminescence degradation of thin film phosphors Zn{sub 2}SiO{sub 4}:Ti and Zn{sub 2}GeO{sub 4}:Mn were investigated in a wide range of e-beam energies, current and power densities. The time dependencies describing decreasing of emission intensity have been found. At high-level densities of e-beam irradiation the specific behavior of long-term degradation processes was observed, which is characteristic with rapid degradation at initial stage and slow consequent decrease of intensity. The most probable mechanisms responsible for long-term processes of degradation in investigated phosphors are proposed.
Date: May 6, 2001
Creator: Bondar, V D; Felter, T E; Hunt, C E; Dubov, Y G & Chakhovskoi, A G
Object Type: Article
System: The UNT Digital Library
DARHT-II Downstream Transport Beamline (open access)

DARHT-II Downstream Transport Beamline

This paper describes the mechanical design of the downstream beam transport line for the second axis of the Dual Axis Radiographic Hydrodynamic Test (DARHT II) Facility. The DARHT-II project is a collaboration between LANL, LBNL and LLNL. DARHT II is a 18.4-MeV, 2000-Amperes, 2-{micro}sec linear induction accelerator designed to generate short bursts of x-rays for the purpose of radiographing dense objects. The downstream beam transport line is approximately 22-meter long region extending from the end of the accelerator to the bremsstrahlung target. Within this proposed transport line there are 12 conventional solenoid, quadrupole and dipole magnets; as well as several specialty magnets, which transport and focus the beam to the target and to the beam dumps. There are two high power beam dumps, which are designed to absorb 80-kJ per pulse during accelerator start-up and operation. Aspects of the mechanical design of these elements are presented.
Date: June 6, 2001
Creator: Westenskow, G A; Bertolini, L R; Duffy, P T & Paul, A C
Object Type: Article
System: The UNT Digital Library
Absorption of Bound States in Hot, Dense Matter (open access)

Absorption of Bound States in Hot, Dense Matter

Preliminary experiments using a long pulse laser generated X-ray source to back-light a short pulse laser heated thin foil have been performed at the Laboratoire pour l'Utilisation des Lasers Intenses (LULI) at Ecole Polytechnique in France. In this experiment, a 2 J, 300 ps, 532 nm laser was used to create the X-ray back-lighter. The primary diagnostic was a von Hamos spectrograph coupled to a 500 fs X-ray streak camera (TREX-VHS) developed at LLNL. This diagnostic combines high collection efficiency ({approx} 10{sup -4} steradians) with fast temporal response ({approx} 500 fs), allowing resolution of extremely transient spectral variations. The TREX-VHS was used to determine the time history, intensity, and spectral content of the back-lighter. The second diagnostic, Fourier Domain Interferometry (FDI), provides information about the position of the critical density of the target and thus the expansion hydrodynamics, laying the ground work for the plasma characterization. The plasmas were determined to be moderately to strongly coupled, resulting in absorption measurements that provide insight into bound states under such conditions.
Date: March 6, 2001
Creator: Shepherd, R.; Audebert, P.; Chenais-Popovics, C.; Geindre, J. P.; Fajardo, M.; Iglesias, C. et al.
Object Type: Article
System: The UNT Digital Library
Dynamic Experiments: an Overview (open access)

Dynamic Experiments: an Overview

Dynamic high pressures are applied rapidly to materials to increase density and temperature, to alter. crystal structure and microstructure, and to change physical and chemical properties [1]. These effects are achieved at high pressures and many are retained on release from high pressures. Today it is possible to achieve pressures of order 50 to 500 GPa (5 Mbar), compressions up to fifteen fold greater than initial solid density in the case of hydrogen, and temperatures ranging from 1 K up to several ev (11,600 K) in condensed matter. At these extreme conditions the bonding , structure, physical properties and chemistry of condensed matter are changed substantially from what they are at ambient. This in turn opens up a whole new range of opportunities for novel condensed matter physics, chemistry, and planetary research at extreme conditions. If high pressure phases could be quenched to ambient, then new opportunities would become available in condensed matter and material sciences, as well as for technological applications. This article is concerned with high pressures achieved dynamically by shock compression [2]. In fact, the terms dynamic and shock are used interchangably to describe pressure pulses above 1 GPa (10 kbar) or so. Because dynamic compression is …
Date: July 6, 2001
Creator: Nellis, W J
Object Type: Article
System: The UNT Digital Library
Use of a Superconducting Tunnel Junction for X-Ray Fluorescence Spectroscopy (open access)

Use of a Superconducting Tunnel Junction for X-Ray Fluorescence Spectroscopy

A superconducting tunnel junction (STJ) in combination with a superconducting absorber of radiation may function as a highly resolving x-ray spectrometer. Electronic excitations, or quasiparticles, are created when a superconductor absorbs an x ray and are detected as an excess tunnel current through the junction. The number of quasiparticles created and the magnitude of the excess current is proportional to the energy of the absorbed x ray. This is similar to existing semiconductor-based spectrometers that measure electron-hole pairs, but with 1000 times more excitations. The energy measurement therefore can be up to 30 times more precise with a superconducting detector than with a semiconductor detector. This work describes the development and testing of an STJ spectrometer design for x-ray fluorescence applications. First, the basic principles of the STJ spectrometer are explained. This is followed by detailed simulations of the variance in the number of quasiparticles produced by absorption of an x ray. This variance is inherent in the detector and establishes an upper limit on the resolving power of the spectrometer. These simulations include effects due to the materials used in the spectrometer and to the multilayer structure of the device. Next, the spectrometer is characterized as functions of operating …
Date: March 6, 2001
Creator: Hiller, L
Object Type: Thesis or Dissertation
System: The UNT Digital Library