Simulation of a D-T Neutron Source for Neutron ScatteringExperiments (open access)

Simulation of a D-T Neutron Source for Neutron ScatteringExperiments

None
Date: September 29, 2003
Creator: Lou, T. P.; Ludewigt, B. A.; Vujic, J. L. & Leung, K. N.
Object Type: Article
System: The UNT Digital Library
Gas Generation Testing of Neptunium Oxide Generated Using the HB-Line Phase IIFlowsheet (open access)

Gas Generation Testing of Neptunium Oxide Generated Using the HB-Line Phase IIFlowsheet

The hydrogen (H{sub 2}) gas generation rate for neptunium dioxide (NpO{sub 2}) samples produced on a laboratory scale using the HB-Line Phase II flowsheet has been measured following exposure to 75% relative humidity (RH). As expected, the observed H{sub 2} generation rates for these samples increase with increasing moisture content. A maximum H{sub 2} generation rate of 1.8 x 10{sup -6} moles per day per kilogram (mol {center_dot} day{sup -1} kg{sup -1}) was observed for NpO{sub 2} samples with approximately one and one-half times (1 1/2 X) the expected specific surface area (SSA) for the HB-Line Phase II product. The SSA of NpO{sub 2} samples calcined at 650 C is similar to plutonium dioxide (PuO{sub 2}) calcined at 950 C according to the Department of Energy (DOE) standard for packaging and storage of PuO{sub 2}. This low SSA of the HB-Line Phase II product limits moisture uptake to less than 0.2 weight percent (wt %) even with extended exposure to 75% RH.
Date: August 29, 2003
Creator: Duffey, J
Object Type: Report
System: The UNT Digital Library
LDRD Final Report: Adaptive Methods for Laser Plasma Simulation (open access)

LDRD Final Report: Adaptive Methods for Laser Plasma Simulation

The goal of this project was to investigate the utility of parallel adaptive mesh refinement (AMR) in the simulation of laser plasma interaction (LPI). The scope of work included the development of new numerical methods and parallel implementation strategies. The primary deliverables were (1) parallel adaptive algorithms to solve a system of equations combining plasma fluid and light propagation models, (2) a research code implementing these algorithms, and (3) an analysis of the performance of parallel AMR on LPI problems. The project accomplished these objectives. New algorithms were developed for the solution of a system of equations describing LPI. These algorithms were implemented in a new research code named ALPS (Adaptive Laser Plasma Simulator) that was used to test the effectiveness of the AMR algorithms on the Laboratory's large-scale computer platforms. The details of the algorithm and the results of the numerical tests were documented in an article published in the Journal of Computational Physics [2]. A principal conclusion of this investigation is that AMR is most effective for LPI systems that are ''hydrodynamically large'', i.e., problems requiring the simulation of a large plasma volume relative to the volume occupied by the laser light. Since the plasma-only regions require less …
Date: January 29, 2003
Creator: Dorr, M R; Garaizar, F X & Hittinger, J A
Object Type: Report
System: The UNT Digital Library
Verification & Validation: Goals, Methods, Levels, and Metrics (open access)

Verification & Validation: Goals, Methods, Levels, and Metrics

This work briefly summarizes the current status of the V and V Program at LLNL regarding goals, methods, timelines, and issues for Verification and Validation (V and V) with Uncertainty Quantification (UQ). The goals are to evaluate various V and V methods, to apply them to computational simulation analyses, and integrate them into methods for Quantitative Certification techniques for the nuclear stockpile. Methods include qualitative and quantitative V and V processes with numerical values for both (qualitative) V and V Level, and (quantitative) validation statements with confidence-bounded uncertainty bands. They describe the critical nature of high quality analyses with quantified V and V, and the essential role of V and V and UQ at specified Confidence levels in evaluating system certification status. Only with quantitative validation statements can rational tradeoffs of various scenarios be made.
Date: April 29, 2003
Creator: Logan, R W & Nitta, C K
Object Type: Article
System: The UNT Digital Library
Radionuclide Incorporation in Secondary Crystalline Minerals Resulting from Chemical Weathering of Selected Waste Glasses: Progress Report: Task kd.5b (open access)

Radionuclide Incorporation in Secondary Crystalline Minerals Resulting from Chemical Weathering of Selected Waste Glasses: Progress Report: Task kd.5b

Experiments were conducted by Pacific Northwest National Laboratory to evaluate potential incorporation of radionuclides in secondary mineral phases that form from weathering vitrified nuclear waste glasses. These experiments were conducted as part of the Immobilized Low-Activity Waste-Performance Assessment (ILAW-PA) to generate data on radionuclide mobilization and transport in a near-field environment of disposed vitrified wastes. The results of these experiments demonstrated that radionuclide sequestration can be significantly enhanced by promoting the formation of cage structured minerals such as sodalite from weathering glasses. These results have important implications regarding radionuclide sequestration/mobilization aspects that are not currently accounted for in the ILAW PA. Additional studies are required to confirm the results and to develop an improved understanding of the mechanisms of sequestration of radionuclides into the secondary and tertiary weathering products of the ILAW glass to help refine how contaminants are released from the near-field disposal region out into the accessible environment. Of particular interest is to determine whether the contaminants remain sequestered in the glass weathering products for hundreds to thousands of years. If the sequestration can be shown to continue for long periods, another immobilization process can be added to the PA analysis and predicted risks should be lower than …
Date: September 29, 2003
Creator: Mattigod, Shas V.; Serne, R. Jeffrey; Legore, Virginia L.; Parker, Kent E.; Orr, Robert D.; McCready, David E. et al.
Object Type: Report
System: The UNT Digital Library
A Mortar Segment-to-Segment Frictional Contact Method for Large Deformations (open access)

A Mortar Segment-to-Segment Frictional Contact Method for Large Deformations

Contact modeling is still one of the most difficult aspects of nonlinear implicit structural analysis. Most 3D contact algorithms employed today use node-on-segment approaches for contacting dissimilar meshes. Two pass node-on-segment contact approaches have the well known deficiency of locking due to over constraint. Furthermore, node-on-segment approaches suffer when individual nodes slide out of contact at contact surface boundaries or when contacting nodes slide from facet to facet. This causes jumps in the contact forces due to the discrete nature of the constraint enforcement and difficulties in convergence for implicit solution techniques. In a previous work, we developed a segment-to-segment contact approach based on the mortar method that was applicable to large deformation mechanics. The approach proved extremely robust since it eliminated the overconstraint which caused ''locking'' and provided smooth force variations in large sliding. Here, we extend this previous approach in to treat frictional contact problems. The proposed approach is then applied to several challenging frictional contact problems which demonstrate its effectiveness.
Date: October 29, 2003
Creator: Puso, M & Laursen, T
Object Type: Article
System: The UNT Digital Library
Instructions for Configuration of the Whole-Building Diagnostician Software Release 2.10-162 Project 2.6 - Enhancement of the Whole Building Diagnostician Task 2.6.3 - WBE Configuration Instructions (open access)

Instructions for Configuration of the Whole-Building Diagnostician Software Release 2.10-162 Project 2.6 - Enhancement of the Whole Building Diagnostician Task 2.6.3 - WBE Configuration Instructions

This document describes how to set up the Whole-Building Energy (WBE) module of the Whole-Building Diagnostician (WBD) for use in monitoring whole-building and major end-use energy consumption. It is a companion to the Instructions for Installation of the Whole-Building Diagnostician Software Release 2.10-162. This document describes how to set up the WBE software to collect new data or process data in existing data bases.
Date: August 29, 2003
Creator: Bauman, Nathan N. & Carlon, Teresa A.
Object Type: Report
System: The UNT Digital Library
Observations of Ferrite/Austenite Transformations in the Heat Affected Zone of 2205 Duplex Stainless Steel Spot Welds Using Time Resolved X-Ray Diffraction (open access)

Observations of Ferrite/Austenite Transformations in the Heat Affected Zone of 2205 Duplex Stainless Steel Spot Welds Using Time Resolved X-Ray Diffraction

Time Resolved X-Ray Diffraction (TRXRD) measurements are made in the Heat Affected Zone (HAZ) of 2205 Duplex Stainless Steel (DSS) spot welds. Both the {gamma} {yields} {delta} and {delta} {yields} {gamma} transformations are monitored as a function of time during the rapid spot weld heating and cooling cycles. These observations are then correlated with calculated thermal cycles. Where the peak temperatures are highest ({approx}1342 C), the {gamma} {yields} {delta} transformation proceeds to completion, leaving a ferritic microstructure at the end of heating. With lower peak temperatures, the {gamma} {yields} {delta} transformation proceeds to only partial completion, resulting in a microstructure containing both transformed and untransformed austenite. Further analyses of the individual diffraction patterns show shifts in the peak positions and peak widths as a function of both time and temperature. In addition, these changes in the peak characteristics are correlated with measured changes in the ferrite volume fraction. Such changes in the peak positions and widths during the {gamma} {yields} {delta} transformation provide an indication of changes occurring in each phase. These changes in peak properties can be correlated with the diffusion of nitrogen and other substitutional alloying elements, which are recognized as the primary mechanisms for this transformation. Upon …
Date: October 29, 2003
Creator: Palmer, T.; Elmer, J. & Babu, S.
Object Type: Article
System: The UNT Digital Library
Lab Scale Production of NpO2 (open access)

Lab Scale Production of NpO2

The Savannah River Site (SRS) plans to disposition its legacy H-Canyon neptunium to Oak Ridge National Laboratory after converting it to oxide in HB-Line. Neptunium oxide, (NpO{sub 2}) was produced at the Savannah River Technology Center using the anticipated HB-Line flowsheet conditions. The oxide was produced from a neptunium nitrate solution via anion exchange, oxalate precipitation, and calcination at either 600 C or 650 C. The 98 grams of NpO{sub 2} produced in the laboratory should be representative of material produced in HB-Line and is to be used for gas generation testing to support radioactive material transportation safety analysis as part of the neptunium stabilization and disposition program at SRS. Results of each step of the oxide production will be presented.
Date: August 29, 2003
Creator: Duffey, J
Object Type: Report
System: The UNT Digital Library
KINETICS OF SLURRY PHASE FISCHER-TROPSCH SYNTHESIS (open access)

KINETICS OF SLURRY PHASE FISCHER-TROPSCH SYNTHESIS

This report covers the first year of this three-year research grant under the University Coal Research program. The overall objective of this project is to develop a comprehensive kinetic model for slurry phase Fischer-Tropsch synthesis on iron catalysts. This model will be validated with experimental data obtained in a stirred tank slurry reactor (STSR) over a wide range of process conditions. The model will be able to predict concentrations of all reactants and major product species (H{sup 2}O, CO{sub 2}, linear 1- and 2-olefins, and linear paraffins) as a function of reaction conditions in the STSR. During the reporting period we have completed one STSR test with precipitated iron catalyst obtained from Ruhrchemie AG (Oberhausen-Holten, Germany). This catalyst was initially in commercial fixed bed reactors at Sasol in South Africa. The catalyst was tested at 13 different sets of process conditions, and had experienced a moderate deactivation during the first 500 h of testing (decrease in conversion from 56% to 50% at baseline process conditions). The second STSR test has been initiated and after 270 h on stream, the catalyst was tested at 6 different sets of process conditions.
Date: September 29, 2003
Creator: Bukur, Dragomir B.; Froment, Gilbert F.; Nowicki, Lech; Wang, Jiang & Ma, Wen-Ping
Object Type: Report
System: The UNT Digital Library
Field Demonstration of a Membrane Process to Recover Heavy Hydrocarbons and to Remove Water from Natural Gas (open access)

Field Demonstration of a Membrane Process to Recover Heavy Hydrocarbons and to Remove Water from Natural Gas

The objective of this project is to design, construct and field demonstrate a membrane system to recover natural gas liquids (NGLs) and remove water from raw natural gas. To convince industry users of the efficiency and reliability of the process, we plan to conduct an extended field test to demonstrate system performance under real-world conditions. The membrane system has been designed and fabricated by Membrane Technology and Research, Inc. (MTR). The MTR membrane system and the compressor are now onsite at BP's Pascagoula, MS plant. The plant is undergoing a very significant expansion and the installation of the membrane unit into the test location is being implemented, albeit at a slower rate than we expected. The startup of the system and conducting of tests will occur in the next six months, depending on the availability of the remaining budget. In the interim, significant commercial progress has been made regarding the introduction of the NGL membrane and systems into the natural gas market.
Date: September 29, 2003
Creator: Lokhandwala, Kaaeid
Object Type: Report
System: The UNT Digital Library
Updated Users' Guide for RSAP -- A Code for Display and Manipulation of Neutron Cross Section Data and SAMMY Fit Results (open access)

Updated Users' Guide for RSAP -- A Code for Display and Manipulation of Neutron Cross Section Data and SAMMY Fit Results

RSAP [1] is a computer code for display and manipulation of neutron cross section data and selected SAMMY output. SAMMY [2] is a multilevel R-matrix code for fitting neutron time-of-flight cross-section data using Bayes' method. This users' guide provides documentation for the recently updated RSAP code (version 6). The code has been ported to the Linux platform, and several new features have been added, including the capability to read cross section data from ASCII pointwise ENDF files as well as double-precision PLT output from SAMMY. A number of bugs have been found and corrected, and the input formats have been improved. Input items are parsed so that items may be separated by spaces or commas.
Date: July 29, 2003
Creator: Sayer, R.O.
Object Type: Report
System: The UNT Digital Library
Linear and Nonlinear Wave Propagation in Negative Refraction Meta-materials (open access)

Linear and Nonlinear Wave Propagation in Negative Refraction Meta-materials

We discuss linear and nonlinear optical wave propagation in a left-handed medium (LHM) or medium of negative refraction (NRM). We use the approach of characterizing the medium response totally by a generalized electric polarization (with a dielectric permittivity {tilde {var_epsilon}}(w, {rvec k})) that can be decomposed into a curl and a non-curl part. The description has a one-to-one correspondence with the usual approach characterizing the LHM response with a dielectric permittivity {var_epsilon}<0 and a magnetic permeability {mu}<0. The latter approach is less physically transparent in the optical frequency region because the usual definition of magnetization loses its physical meaning. Linear wave propagation in LHM or NRM is characterized by negative refraction and negative group velocity that could be clearly manifested by ultra-short pulse propagation in such a medium. Nonlinear optical effects in LHM can be predicted from the same calculations adopted for ordinary media using our general approach.
Date: May 29, 2003
Creator: Agranovich, V.M.; Shen, Y.R.; Baughman, R.H. & Zakhidov, A.A.
Object Type: Article
System: The UNT Digital Library
RP-5 Renewable Energy Efficiency Project (open access)

RP-5 Renewable Energy Efficiency Project

None
Date: October 29, 2003
Creator: Clifton, Neil; Whitman, Eliza Jane & Zughbi, Jamal A.
Object Type: Report
System: The UNT Digital Library
Are both symmetric and buckled dimers on Si(100) minima? Density functional and multireference perturbation theory calculations (open access)

Are both symmetric and buckled dimers on Si(100) minima? Density functional and multireference perturbation theory calculations

We report a spin-unrestricted density functional theory (DFT) solution at the symmetric dimer structure for cluster models of Si(100). With this solution, it is shown that the symmetric structure is a minimum on the DFT potential energy surface, although higher in energy than the buckled structure. In restricted DFT calculations the symmetric structure is a saddle point connecting the two buckled minima. To further assess the effects of electron correlation on the relative energies of symmetric versus buckled dimers on Si(100), multireference second order perturbation theory (MRMP2) calculations are performed on these DFT optimized minima. The symmetric structure is predicted to be lower in energy than the buckled structure via MRMP2, while the reverse order is found by DFT. The implications for recent experimental interpretations are discussed.
Date: August 29, 2003
Creator: Jung, Yousung; Shao, Yihan; Gordon, Mark S.; Doren, Douglas J. & Head-Gordon, Martin
Object Type: Article
System: The UNT Digital Library
Computational economy improvements in PRISM (open access)

Computational economy improvements in PRISM

The PRISM piecewise solution mapping procedure, in which the solution of the chemical kinetic ODE system is parameterized with quadratic polynomials, is applied to CFD simulations of H{sub 2}+air combustion. Initial cost of polynomial construction is expensive, but it is recouped as the polynomial is reused. We present two methods that help us to parameterize only in places that will ultimately have high reuse. We also implement non-orthogonal Gosset factorial designs, that reduce polynomial construction costs by a factor of two over previously used orthogonal factorial designs.
Date: January 29, 2003
Creator: Tonse, Shaheen R. & Brown, Nancy J.
Object Type: Article
System: The UNT Digital Library
Effects of Scatter Modeling on Time-Activity Curves Estimated Directly From Dynamic SPECT Projections (open access)

Effects of Scatter Modeling on Time-Activity Curves Estimated Directly From Dynamic SPECT Projections

Quantitative analysis of uptake and washout of cardiac single photon emission computed tomography (SPECT) radiopharmaceuticals has the potential to provide better contrast between healthy and diseased tissue, compared to conventional reconstruction of static images. Previously, we used B-splines to model time-activity curves (TACs) for segmented volumes of interest and developed fast least-squares algorithms to estimate spline TAC coefficients and their statistical uncertainties directly from dynamic SPECT projection data. This previous work incorporated physical effects of attenuation and depth-dependent collimator response. In the present work, we incorporate scatter and use a computer simulation to study how scatter modeling affects directly estimated TACs and subsequent estimates of compartmental model parameters. An idealized single-slice emission phantom was used to simulate a 15 min dynamic {sup 99m}Tc-teboroxime cardiac patient study in which 500,000 events containing scatter were detected from the slice. When scatter was modeled, unweighted least-squares estimates of TACs had root mean square (RMS) error that was less than 0.6% for normal left ventricular myocardium, blood pool, liver, and background tissue volumes and averaged 3% for two small myocardial defects. When scatter was not modeled, RMS error increased to average values of 16% for the four larger volumes and 35% for the small …
Date: October 29, 2003
Creator: Reutter, Bryan W.; Gullberg, Grant T. & Huesman, Ronald H.
Object Type: Article
System: The UNT Digital Library
CAPACITIVE TOMOGRAPHY FOR THE LOCATION OF PLASTIC PIPE (open access)

CAPACITIVE TOMOGRAPHY FOR THE LOCATION OF PLASTIC PIPE

Throughout the utility industry, there is high interest in subsurface imaging of plastic, ceramic, and metallic objects because of the cost, reliability, and safety benefits available in avoiding impacts with the existing infrastructure and in reducing inappropriate excavations. Industry interest in locating plastic pipe has resulted in funding available for the development of technologies that enable this imaging. Gas Technology Institute (GTI) proposes to develop a compact and inexpensive capacitive tomography imaging sensor that takes the form of a flat plate or flexible mat that can be placed on the ground to image objects embedded in the soil. A compact, low-cost sensor that can image objects through soil could be applied to multiple operations and will produce a number of cost savings for the gas industry. In a stand-alone mode, it could be used to survey an area prior to excavation. The technology would improve the accuracy and reliability of any operation that involves excavation by locating or avoiding buried objects. An accurate subsurface image of an area will enable less costly keyhole excavations and other cost-saving techniques. Ground penetrating radar (GPR) has been applied to this area with limited success. Radar requires a high-frequency carrier to be injected into …
Date: July 29, 2003
Creator: Huber, Brian J.
Object Type: Report
System: The UNT Digital Library
Stabilized numerical solutions of three-phase porous media flow using a multiscale finite element formulation (open access)

Stabilized numerical solutions of three-phase porous media flow using a multiscale finite element formulation

None
Date: January 29, 2003
Creator: Juanes, Ruben & Patzek, Tadeusz W.
Object Type: Report
System: The UNT Digital Library
DISTRIBUTED GENERATION POWER UNITS AT MARGINAL OIL WELL SITES (open access)

DISTRIBUTED GENERATION POWER UNITS AT MARGINAL OIL WELL SITES

The CEC approved funding on April 9, 2003 for $1,000,000.00 instead of the $1,500,000.00 COPE requested for the project. A kickoff meeting with the California Energy Commission (CEC) was held on Monday, April 14, 2003, in their Sacramento, CA offices. Mark Carl, IOGCC project manager for the DOE grant, attended this meeting, along with Bob Fickes with COPE, Edan Prabhu, Mike Merlo and CEC officials. The change in funding by the CEC required a modification in the scope of work and an amended form DOE F 4600.1. The modifications were completed and the IOGCC received approval to commence work on the project on May 9, 2003. On May 29, 2003, Virginia Weyland with DOE/NETL, Mark Carl with IOGCC, and Bob Fickes with COPE, Edan Prabhu and Mike Merlo, consultants with COPE, participated in a teleconference kick-off meeting. During May, 2003, COPE canvassed its membership for potential locations for the four test sites. They received a very good response and have identified at least two potential sites for each of the four test sites. COPE has been obtaining gas samples from the various potential lease sites for analyses to verify the chemical properties analyses which the oil and gas producers provided …
Date: October 29, 2003
Creator: Carl, Mark A.
Object Type: Report
System: The UNT Digital Library
Fracture and fatigue resistance of Mo-Si-B alloys for ultrahigh-temperature structural applications (open access)

Fracture and fatigue resistance of Mo-Si-B alloys for ultrahigh-temperature structural applications

Fracture and fatigue-crack growth properties are examined for a series of Mo-Mo3Si-Mo5SiB2 containing alloys, which utilize a continuous a-Mo matrix to achieve unprecedented room-temperature fracture resistance (>20 MPaAm). Mechanistically, these properties are explained in terms of toughening by crack trapping and crack bridging by the more ductile a-Mo phase.
Date: August 29, 2003
Creator: Kruzic, J. J.; Schneibel, J. H. & Ritchie, R. O.
Object Type: Article
System: The UNT Digital Library
A week of SRI 2003 in San Francisco (open access)

A week of SRI 2003 in San Francisco

The Eighth International Conference on Synchrotron Radiation (SRI 2003) ended its August 25-28 run at the Yerba Buena Center for the Arts in San Francisco with almost as many in attendance as at the beginning. The steady attendance was surely a tribute to the quality of the program and the excitement it generated among the more than 700 registrants who gathered for four days of plenary talks, parallel sessions, and posters, as well as facility tours of the ALS and SSRL on August 29.
Date: September 29, 2003
Creator: Robinson, Art
Object Type: Article
System: The UNT Digital Library
Towards increased policy relevance in energy modeling (open access)

Towards increased policy relevance in energy modeling

Historically, most energy models were reasonably equipped to assess the impact of a subsidy or change in taxation, but are often insufficient to assess the impact of more innovative policy instruments. We evaluate the models used to assess future energy use, focusing on industrial energy use. We explore approaches to engineering-economic analysis that could help improve the realism and policy relevance of engineering-economic modeling frameworks. We also explore solutions to strengthen the policy usefulness of engineering-economic analysis that can be built from a framework of multi-disciplinary cooperation. We focus on the so-called ''engineering-economic'' (or ''bottom-up'') models, as they include the amount of detail that is commonly needed to model policy scenarios. We identify research priorities for the modeling framework, technology representation in models, policy evaluation and modeling of decision-making behavior.
Date: July 29, 2003
Creator: Worrell, Ernst; Ramesohl, Stephan & Boyd, Gale
Object Type: Article
System: The UNT Digital Library
Railplug Ignition System for Enhanced Engine Performance and Reduced Maintenance Progress Report (open access)

Railplug Ignition System for Enhanced Engine Performance and Reduced Maintenance Progress Report

During the first 6 months of this project, four subtasks were scheduled. Two of these commenced earlier than originally proposed. The experimental task, development of new railplug designs, was completed on schedule. The three numerical subtasks were not completed on schedule. However, this is not expected to affect the capability to complete the overall project on schedule. Because we are early in the project, no results or conclusions were generated. Our progress included development of new railplug geometries, to be tested during the second 6 months of the project, and development of an initial 3D model. Progress was also made in development of the appropriate chemical kinetics and generation of a model for the ignition circuit.
Date: May 29, 2003
Creator: Matthews, Ron
Object Type: Report
System: The UNT Digital Library