Resource Type

119 Matching Results

Results open in a new window/tab.

DOWNSTREAM IMPACTS OF SLUDGE MASS REDUCTION VIA ALUMINUM DISSOLUTION ON DWPF PROCESSING OF SAVANNAH RIVER SITE HIGH LEVEL WASTE - 9382 (open access)

DOWNSTREAM IMPACTS OF SLUDGE MASS REDUCTION VIA ALUMINUM DISSOLUTION ON DWPF PROCESSING OF SAVANNAH RIVER SITE HIGH LEVEL WASTE - 9382

The SRS sludge that was to become a major fraction of Sludge Batch 5 (SB5) for the Defense Waste Processing Facility (DWPF) contained a large fraction of H-Modified PUREX (HM) sludge, containing a large fraction of aluminum compounds that could adversely impact the processing and increase the vitrified waste volume. It is beneficial to reduce the non-radioactive fraction of the sludge to minimize the number of glass waste canisters that must be sent to a Federal Repository. Removal of aluminum compounds, such as boehmite and gibbsite, from sludge can be performed with the addition of NaOH solution and heating the sludge for several days. Preparation of SB5 involved adding sodium hydroxide directly to the waste tank and heating the contents to a moderate temperature through slurry pump operation to remove a fraction of this aluminum. The Savannah River National Laboratory (SRNL) was tasked with demonstrating this process on actual tank waste sludge in our Shielded Cells Facility. This paper evaluates some of the impacts of aluminum dissolution on sludge washing and DWPF processing by comparing sludge processing with and without aluminum dissolution. It was necessary to demonstrate these steps to ensure that the aluminum removal process would not adversely impact …
Date: January 14, 2009
Creator: Pareizs, J; Cj Bannochie, C; Michael Hay, M & Daniel McCabe, D
System: The UNT Digital Library
Theoretical Overview on Recent Developments in Transverse Spin Physics (open access)

Theoretical Overview on Recent Developments in Transverse Spin Physics

Transverse-spin physics has been very active and rapidly developing in the last few years. In this talk, I will briefly summarize recent theoretical developments, focusing on the associated QCD dynamics in transverse spin physics.
Date: January 14, 2009
Creator: Yuan, Feng
System: The UNT Digital Library
Simulating atmosphere flow for wind energy applications with WRF-LES (open access)

Simulating atmosphere flow for wind energy applications with WRF-LES

Forecasts of available wind energy resources at high spatial resolution enable users to site wind turbines in optimal locations, to forecast available resources for integration into power grids, to schedule maintenance on wind energy facilities, and to define design criteria for next-generation turbines. This array of research needs implies that an appropriate forecasting tool must be able to account for mesoscale processes like frontal passages, surface-atmosphere interactions inducing local-scale circulations, and the microscale effects of atmospheric stability such as breaking Kelvin-Helmholtz billows. This range of scales and processes demands a mesoscale model with large-eddy simulation (LES) capabilities which can also account for varying atmospheric stability. Numerical weather prediction models, such as the Weather and Research Forecasting model (WRF), excel at predicting synoptic and mesoscale phenomena. With grid spacings of less than 1 km (as is often required for wind energy applications), however, the limits of WRF's subfilter scale (SFS) turbulence parameterizations are exposed, and fundamental problems arise, associated with modeling the scales of motion between those which LES can represent and those for which large-scale PBL parameterizations apply. To address these issues, we have implemented significant modifications to the ARW core of the Weather Research and Forecasting model, including the …
Date: January 14, 2008
Creator: Lundquist, J K; Mirocha, J D; Chow, F K; Kosovic, B & Lundquist, K A
System: The UNT Digital Library
NEW METHOD FOR REMOVAL OF SPECTRAL INTERFERENCES FOR BERYLLIUM ASSAY USING INDUCTIVELY COUPLED PLASMA ATOMIC EMISSION SPECTROMETRY (open access)

NEW METHOD FOR REMOVAL OF SPECTRAL INTERFERENCES FOR BERYLLIUM ASSAY USING INDUCTIVELY COUPLED PLASMA ATOMIC EMISSION SPECTROMETRY

Beryllium has been used widely in specific areas of nuclear technology. Frequent monitoring of air and possible contaminated surfaces in U.S Department of Energy (DOE) facilities is required to identify potential health risks and to protect DOE workers from beryllium-contaminated dust. A new method has been developed to rapidly remove spectral interferences prior to beryllium (Be) measurement by inductively-coupled plasma atomic emission spectrometry (ICP-AES). The ion exchange separation removes uranium (U), thorium (Th), niobium (Nb), vanadium (V), molybdenum (Mo), zirconium (Zr), tungsten (W), iron (Fe), chromium (Cr), cerium (Ce), erbium (Er) and titanium (Ti). A stacked column consisting of Diphonix Resin{reg_sign} and TEVA Resin{reg_sign} reduces the levels of the spectral interferences so that low level Be measurements can be performed accurately. If necessary, an additional anion exchange separation can be used for further removal of interferences, particularly chromium. The method has been tested using spiked filters, spiked wipe samples and certified reference material standards with high levels of interferences added. The method provides very efficient removal of spectral interferences with very good accuracy and precision for beryllium on filters or wipes. A vacuum box system is employed to reduce analytical time and reduce labor costs.
Date: January 14, 2008
Creator: Maxwell, S; Matthew Nelson, M; Linda Youmans, L & Maureen Bernard, M
System: The UNT Digital Library
A Linear RFQ Ion Trap for the Enriched Xenon Observatory (open access)

A Linear RFQ Ion Trap for the Enriched Xenon Observatory

The design, construction, and performance of a linear radio-frequency ion trap (RFQ) intended for use in the Enriched Xenon Observatory (EXO) are described. EXO aims to detect the neutrinoless double-beta decay of {sup 136}Xe to {sup 136}Ba. To suppress possible backgrounds EXO will complement the measurement of decay energy and, to some extent, topology of candidate events in a Xe filled detector with the identification of the daughter nucleus ({sup 136}Ba). The ion trap described here is capable of accepting, cooling, and confining individual Ba ions extracted from the site of the candidate double-beta decay event. A single trapped ion can then be identified, with a large signal-to-noise ratio, via laser spectroscopy.
Date: January 14, 2008
Creator: Flatt, B.; Green, M.; Wodin, J.; DeVoe, R.; Fierlinger, P.; Gratta, G. et al.
System: The UNT Digital Library
Comment on ``Experimental Free Energy Reconstruction From Single-Molecule Force Spectroscopy Using Jarzynski's Equality'' (open access)

Comment on ``Experimental Free Energy Reconstruction From Single-Molecule Force Spectroscopy Using Jarzynski's Equality''

Harris, Song and Kiang [1] (HSK) describe their results on reconstructing the free energy profiles for both the stretch of the titin polymer, and the unfolding of an individual I27 domain. The new finding reported in [1] is the measurement of the free energy barrier (or activation energy) to unfolding the I27 domain. Due to a misinterpretation of the mechanics involved, the free energy surface (and thus the energy barrier) to unfolding the I27 domain was not measured.
Date: January 14, 2008
Creator: Friddle, R. W.
System: The UNT Digital Library
Sensor Development and Readout Prototyping for the STAR Pixel Detector (open access)

Sensor Development and Readout Prototyping for the STAR Pixel Detector

The STAR experiment at the Relativistic Heavy Ion Collider (RHIC) is designing a new vertex detector. The purpose of this upgrade detector is to provide high resolution pointing to allow for the direct topological reconstruction of heavy flavor decays such as the D{sup 0} by finding vertices displaced from the collision vertex by greater than 60 microns. We are using Monolithic Active Pixel Sensor (MAPS) as the sensor technology and have a coupled sensor development and readout system plan that leads to a final detector with a <200 {micro}s integration time, 400 M pixels and a coverage of -1 < {eta} < 1. We present our coupled sensor and readout development plan and the status of the prototyping work that has been accomplished.
Date: January 14, 2009
Creator: Greiner, L.; Anderssen, E.; Matis, H. S.; Ritter, H. G.; Stezelberger, T.; Szelezniak, M. et al.
System: The UNT Digital Library
Chamonium Spectroscopy at BaBar (open access)

Chamonium Spectroscopy at BaBar

The charmonium-like states, Y(4260), Y(4350), produced via initial state radiation, as well as the X(3872), and Y(3940), produced in B meson decays from the BABAR B-factory are reviewed. These mesons do not seem consistent with conventional charmonium models, and several alternate hypotheses have been proposed to explain these new discoveries.
Date: January 14, 2008
Creator: Mokhtar, Arafat Gabareen & U., /Colorado State
System: The UNT Digital Library
Investigation of Radar Propagation in Buildings: A 10 Billion Element Cartesian-Mesh FETD Simulation (open access)

Investigation of Radar Propagation in Buildings: A 10 Billion Element Cartesian-Mesh FETD Simulation

In this paper large scale full-wave simulations are performed to investigate radar wave propagation inside buildings. In principle, a radar system combined with sophisticated numerical methods for inverse problems can be used to determine the internal structure of a building. The composition of the walls (cinder block, re-bar) may effect the propagation of the radar waves in a complicated manner. In order to provide a benchmark solution of radar propagation in buildings, including the effects of typical cinder block and re-bar, we performed large scale full wave simulations using a Finite Element Time Domain (FETD) method. This particular FETD implementation is tuned for the special case of an orthogonal Cartesian mesh and hence resembles FDTD in accuracy and efficiency. The method was implemented on a general-purpose massively parallel computer. In this paper we briefly describe the radar propagation problem, the FETD implementation, and we present results of simulations that used over 10 billion elements.
Date: January 14, 2008
Creator: Stowell, M. L.; Fasenfest, B. J. & White, D. A.
System: The UNT Digital Library
A Time Projection Chamber for precision 239Pu(n,f) cross section measurement (open access)

A Time Projection Chamber for precision 239Pu(n,f) cross section measurement

High precision measurements of the {sup 239}Pu(n,f) cross section have been identified as important for the Global Nuclear Energy Partnership (GNEP) and other programs. Currently the uncertainty on this cross section is of the order 2-3% for neutron energies below 14 MeV and the goal is to reduce this to less than 1%. The Time Projection Chamber (TPC) has been identified as a possible tool to make this high precision measurement.
Date: January 14, 2008
Creator: Heffner, M
System: The UNT Digital Library
Halide laser glasses (open access)

Halide laser glasses

Energy storage and energy extraction are of prime importance for efficient laser action and are affected by the line strengths and linewidths of optical transitions, excited-state lifetimes, nonradiative decay processes, spectroscopic inhomogeneities, nonlinear refractive index, and damage threshold. These properties are all host dependent. To illustrate this, the spectroscopic properties of Nd/sup 3 +/ have been measured in numerous oxide, oxyhalide, and halide glasses. A table summarizes the reported ranges of stimulated emission cross sections, peak wavelengths, linewidths, and radiative lifetimes associated with the /sup 4/F/sub 3/2/ ..-->.. /sup 4/I/sub 11/2/ lasing transition.
Date: January 14, 1982
Creator: Weber, M. J.
System: The UNT Digital Library
PHIGS PLUS for scientific graphics (open access)

PHIGS PLUS for scientific graphics

This paper gives a brief overview of the use of computer graphics standards in the scientific community. It particularly details how how PHIGS PLUS meets the needs of users at the Lawrence Livermore National Laboratory. Although standards for computer graphics have improved substantially over the past decade, their acceptance in the scientific community has been slow. As the use and diversity of computers has increased, the scientific graphics libraries have not been able to keep pace with the additional capabilities these new machines offer. Therefore, several organizations have or are now working on converting their scientific libraries to reset upon a portable standard. This paper will address why is transition has been so slow and offer suggestions for future standards work to enhance scientific visualization. This work was performed under the auspices of the US Department of Energy by Lawrence Livermore National Laboratory under contract No. W-7405-Eng-48.
Date: January 14, 1991
Creator: Crawfis, R.A.
System: The UNT Digital Library
Thermowell flow-induced vibrations measured in laboratory and FFTF plant piping (open access)

Thermowell flow-induced vibrations measured in laboratory and FFTF plant piping

This paper describes the various laboratory and field tests conducted to assure that flow-induced vibrations do not exist in the piping thermowells of the Fast Flux Test Facility. FFTF thermowells are subjected to a wide range of flowing sodium velocities during testing and operation. Early design work indicated a need to provide special attention to thermowell response in the drag direction at the higher sodium flow rates associated with FFTF testing. The results of this study provide some additional insight into response characteristics of a tube in liquid cross flow with emphasis on motion in the drag direction.
Date: January 14, 1980
Creator: Bartholf, L.W.
System: The UNT Digital Library
Lessons learned during the D & D of Fernald Plant 7 (open access)

Lessons learned during the D & D of Fernald Plant 7

This document contains information about lessons learned from the decontamination and decommissioning of the Feed Materials Production Center in Fernald Ohio. The information relates to Plant 7 which was constructed to house processes for the reduction of uranium hexafluoride to uranium tetrafluoride. Topics discussed include: washdown, lockdown, asbestos removal, and bidding for dismantlement projects.
Date: January 14, 1994
Creator: Motl, G. P. & Borgman, T. D.
System: The UNT Digital Library
Space reactor fuel element testing in upgraded TREAT (open access)

Space reactor fuel element testing in upgraded TREAT

The testing of candidate fuel elements at prototypic operating conditions with respect to temperature, power density, hydrogen coolant flow rate, etc., a crucial component in the development and qualification of nuclear rocket engines based on the Particle Bed Reactor (PBR), NERVA-derivative, and other concepts. Such testing may be performed at existing reactors, or at new facilities. A scoping study has been performed to assess the feasibility of testing PBR based fuel elements at the TREAT reactor. initial results suggest that full-scale PBR, elements could be tested at an average energy deposition of {approximately}60--80 MW-s/L in the current TREAT reactor. If the TREAT reactor was upgraded to include fuel elements with a higher temperature limit, average energy deposition of {approximately}100 MW/L may be achievable.
Date: January 14, 1993
Creator: Todosow, M.; Bezler, P.; Ludewig, H. & Kato, W. Y.
System: The UNT Digital Library
Insights to Repository Performance Through Study of a Nuclear Test Site (open access)

Insights to Repository Performance Through Study of a Nuclear Test Site

United States high-level nuclear waste from nuclear weapons production, naval propulsion programs, and the processing of commercial spent nuclear fuels is scheduled for immobilization in glass waste forms prior to permanent disposal in a mined geologic repository. Considerable attention has been directed to assessments of the subsequent long-term release of radionuclides from a repository under saturated and partially saturated conditions. Credible predictions of dose from a repository rely on insights to radionuclide sequestration in the glass, mechanisms of glass degradation, and radionuclide solubility and transport in the near-field. Underground nuclear test sites offer an unprecedented opportunity to evaluate processes relevant to repository performance in the absence of engineered barriers. Radionuclide migration programs at the Nevada Test Site represent a twenty-five year investment in the systematic investigation of the diverse radiologic source term from weapons testing and the evolution of the hydrologic source term which includes radionuclides dissolved in or otherwise available for transport by groundwater. The geology, hydrology, and geochemistry of the Nevada Test Site which includes the proposed Yucca Mountain repository provides an ideal natural laboratory to assess long-term radionuclide transport in the near and far-field. The Yucca Mountain repository shares with adjacent testing areas the following features: correlative …
Date: January 14, 2000
Creator: Smith, D. K.; Kersting, A. B.; Thompson, J. L. & Finnegan, D. L.
System: The UNT Digital Library
DYNAMICAL RESPONSE OF QUASI ID MOTT INSULATORS. (open access)

DYNAMICAL RESPONSE OF QUASI ID MOTT INSULATORS.

At low energies certain one dimensional Mott insulators can be described in terms of an exactly solvable quantum field theory, the U(1) Thirring model. Using exact results derived from integrability we determine dynamical properties like the frequency dependent optical conductivity and the single-particle Green's function. We discuss the effects of a small temperature and the effects on interchain tunneling in a model of infinitely many weakly coupled chains.
Date: January 14, 2004
Creator: Essler, F. H. L. & Tsvelika, A. M.
System: The UNT Digital Library
Electrically detected magnetic resonance in a W-band microwave cavity (open access)

Electrically detected magnetic resonance in a W-band microwave cavity

We describe a low-temperature sample probe for the electrical detection of magnetic resonance in a resonant W-band (94 GHz) microwave cavity. The advantages of this approach are demonstrated by experiments on silicon field-effect transistors. A comparison with conventional low-frequency measurements at X-band (9.7 GHz) on the same devices reveals an up to 100-fold enhancement of the signal intensity. In addition, resonance lines that are unresolved at X-band are clearly separated in the W-band measurements. Electrically detected magnetic resonance at high magnetic fields and high microwave frequencies is therefore a very sensitive technique for studying electron spins with an enhanced spectral resolution and sensitivity.
Date: January 14, 2011
Creator: Lang, V.; Lo, C. C.; George, R. E.; Lyon, S. A.; Bokor, J.; Schenkel, T. et al.
System: The UNT Digital Library
Highly 15N-Enriched Chondritic Clasts in the Isheyevo Meteorite (open access)

Highly 15N-Enriched Chondritic Clasts in the Isheyevo Meteorite

The metal-rich carbonaceous chondrites (CB and CH) have the highest whole-rock {sup 15}N enrichment ({delta}{sup 15}N up to +1500{per_thousand}), similar to {delta}{sup 15}N values reported in micron-sized regions (hotspots) of Interplanetary Dust Particles (IDPs) of possibly cometary origin and fine-grained matrices of unmetamorphosed chondrites. These {sup 15}N-rich hotspots are commonly attributed to low-temperature ion-molecule reactions in the protosolar molecular cloud or in the outer part of the protoplanetary disk. The nature of the whole-rock {sup 15}N enrichment of the metal-rich chondrites is not understood. We report a discovery of a unique type of primitive chondritic clasts in the CH/CB-like meteorite Isheyevo, which provides important constraints on the origin of {sup 15}N anomaly in metal-rich chondrites and nitrogen-isotope fractionation in the Solar System. These clasts contain tiny chondrules and refractory inclusions (5-15 {micro}m in size), and abundant ferromagnesian chondrule fragments (1-50 {micro}m in size) embedded in the partly hydrated, fine-grained matrix material composed of olivines, pyroxenes, poorly-organized aromatic organics, phyllosilicates and other hydrous phases. The mineralogy and oxygen isotope compositions of chondrules and refractory inclusions in the clasts are similar to those in the Isheyevo host, suggesting formation at similar heliocentric distances. In contrast to the previously known extraterrestrial samples, the …
Date: January 14, 2009
Creator: Bonal, L; Huss, G R; Krot, A N; Nagashima, K; Ishii, H A; Bradley, J P et al.
System: The UNT Digital Library
CO Oxidation at the Interface of Au Nanoclusters and the Stepped-CeO2(111) Surface (open access)

CO Oxidation at the Interface of Au Nanoclusters and the Stepped-CeO2(111) Surface

To reveal the richer chemistry of CO oxidation by CeO2 supported Au Nanoclusters NCs)/Nanoparticles, we design a Au12 supported on a stepped-CeO2 model (Au/CeO2-step) and study various kinds of CO oxidation mechanisms at the interface of the Au/CeO2-step: oxygen spillover from the CeO2 to the Au NCs;2 CO oxidation by the O2 bound to the Au-Ce3+ interface;3 and CO oxidation by the Mars-van Krevelen (M-vK) mechanism.4 DFT+U calculations show that lattice oxygen at the CeO2 step edge oxidizes CO bound to Au NCs by the M-vK mechanism. CO2 desorption determines the rate of CO oxidation and the vacancy formation energy (Evac) is a reactivity descriptor for CO oxidation. The maximum Evac that insures spontaneous CO2 production is higher for the Au/CeO2-step than the Au/CeO2-surface suggesting that the CeO2-step is a better supporting material than the CeO2-surface for CO oxidation by the Au/CeO2. Our results also suggest that for CO oxidation by Au NCs supported on nano- or meso-structured CeO2, which is the case of industrial catalysts, the M-vK mechanism accounts for a large portion of the total activity.
Date: January 14, 2013
Creator: Y., Kim H. & Henkelman, G.
System: The UNT Digital Library
Three-phase region of D/sub 2/-DT-T/sub 2/ (open access)

Three-phase region of D/sub 2/-DT-T/sub 2/

The three-phase region of various mixtures of D/sub 2/, DT, and T/sub 2/ has been investigated through plots of temperature and pressure vs time. The liquid surface for a temperature-vs-composition plot is obtained from the points of first freezing. The solid surface is obtained from the points of first melting after a quick freeze. All components appear miscible in both liquid and solid phases from 17 to 22 K. From analogy to H-T systems, the chemical equilibria in these D-T systems were assumed to be the same at experimental temperatures as at room temperature. The Raoult's-law total pressure is calculated from an analysis of all six species; the experimental pressure is at the most 3.5% higher than the Raoult's-law pressure. Raoult's law is used to obtain gas-phase compositions; the phase diagram shows a maximum temperature difference of 0.15 K between the gas and solid surfaces. As an example for 50-50 mole % of liquid D-T at about 19.7 K, the gas will contain about 42% T and the solid 52%. Codes giving the equilibrium vapor pressures of pure components for both the solid and liquid from 4 to 30 K are listed.
Date: January 14, 1977
Creator: Souers, P. C.; Kelly, E.; Roberts, P. E.; Fearon, D. & Tsugawa, R. T.
System: The UNT Digital Library
Massively Multi-core Acceleration of a Document-Similarity Classifier to Detect Web Attacks (open access)

Massively Multi-core Acceleration of a Document-Similarity Classifier to Detect Web Attacks

This paper describes our approach to adapting a text document similarity classifier based on the Term Frequency Inverse Document Frequency (TFIDF) metric to two massively multi-core hardware platforms. The TFIDF classifier is used to detect web attacks in HTTP data. In our parallel hardware approaches, we design streaming, real time classifiers by simplifying the sequential algorithm and manipulating the classifier's model to allow decision information to be represented compactly. Parallel implementations on the Tilera 64-core System on Chip and the Xilinx Virtex 5-LX FPGA are presented. For the Tilera, we employ a reduced state machine to recognize dictionary terms without requiring explicit tokenization, and achieve throughput of 37MB/s at slightly reduced accuracy. For the FPGA, we have developed a set of software tools to help automate the process of converting training data to synthesizable hardware and to provide a means of trading off between accuracy and resource utilization. The Xilinx Virtex 5-LX implementation requires 0.2% of the memory used by the original algorithm. At 166MB/s (80X the software) the hardware implementation is able to achieve Gigabit network throughput at the same accuracy as the original algorithm.
Date: January 14, 2010
Creator: Ulmer, C.; Gokhale, M.; Top, P.; Gallagher, B. & Eliassi-Rad, T.
System: The UNT Digital Library
Two-phase-flow cooling concept for fusion reactor blankets (open access)

Two-phase-flow cooling concept for fusion reactor blankets

The new two-phase heat transfer medium proposed is a mixture of potassium droplets and helium which permits blanket operation at hih temperature and low pressure, while maintaining acceptable pumping power requirements, coolant ducting size, and blanket structure fractions. A two-phase flow model is described. The helium pumping power and the primary heat transfer loop are discussed. (MOW)
Date: January 14, 1977
Creator: Bender, D. J. & Hoffman, M. A.
System: The UNT Digital Library
System Planning With the Hanford Waste Operations Simulator (open access)

System Planning With the Hanford Waste Operations Simulator

At the U. S. Department of Energy's Hanford Site in southeastern Washington State, 216 million liters (57 million gallons) of nuclear waste is currently stored in aging underground tanks, threatening the Columbia River. The River Protection Project (RPP), a fully integrated system of waste storage, retrieval, treatment, and disposal facilities, is in varying stages of design, construction, operation, and future planning. These facilities face many overlapping technical, regulatory, and financial hurdles to achieve site cleanup and closure. Program execution is ongoing, but completion is currently expected to take approximately 40 more years. Strategic planning for the treatment of Hanford tank waste is by nature a multi-faceted, complex and iterative process. To help manage the planning, a report referred to as the RPP System Plan is prepared to provide a basis for aligning the program scope with the cost and schedule, from upper-tier contracts to individual facility operating plans. The Hanford Tank Waste Operations Simulator (HTWOS), a dynamic flowsheet simulation and mass balance computer model, is used to simulate the current planned RPP mission, evaluate the impacts of changes to the mission, and assist in planning near-term facility operations. Development of additional modeling tools, including an operations research model and a …
Date: January 14, 2010
Creator: Crawford, T. W.; Certa, P. J. & Wells, M. N.
System: The UNT Digital Library