Barrier Foil Heating Simulations Using LASNEX (open access)

Barrier Foil Heating Simulations Using LASNEX

It is necessary to place a barrier foil in front of the X-ray converter target to prevent the backstreaming ions. This research note presents the simulations of foil heating using the latest EOS tables. LASNEX simulations are carried out using both DARHT-II and ETA-II beam parameters. Results for all the foils studied here, using the DARHT-II beam parameters, show that the integrated line density along the axis at the end of the 4th pulse remains essentially unchanged even if the foils are heated by beams with relatively small beam spot sizes. The temperature can reach up to 3000 C on graphite foil but can only reach several hundred degree Celsius on Mylar foil. Simulations also show that ETA-II beam can create a ''burn-through'' hole on all the foils except graphite and diamond foils, which may require pre-heat. The threshold beam spot size required for hole formation will be compared with LASNEX simulation for the purpose of code verification.
Date: March 12, 2002
Creator: Ho, D. D.-M.
System: The UNT Digital Library
Settling Test Using Simulants to Evaluate Uranium Metal Distribution in K Basin Sludge (open access)

Settling Test Using Simulants to Evaluate Uranium Metal Distribution in K Basin Sludge

This report presents the results of a large-scale settling test conducted with a K Basin sludge simulant that included metallic tungsten/cobalt (W/Co) fragments (density {approx}14.5 g/cm3) as a surrogate for uranium metal (density 19 g/cm3). The objective of the testing was to gain insight into how uranium metal is likely to be distributed within the K Basin sludge loaded into the large-diameter containers (LDCs) that will be used for storage at T Plant. In the LDCs, uranium metal will react with water and generate heat and hydrogen gas. During loading, transportation, and storage operations, the uranium metal distribution in the LDCs will have an impact on the thermal stability. Approximately 50 m3 of K Basin sludge have accumulated during the storage of more than 2100 metric tons of N Reactor fuel elements in two water-filled concrete pools (K East and K West Basins) in the 100K Area of the Hanford Site.
Date: April 12, 2002
Creator: Schmidt, Andrew J. & Elmore, Monte R.
System: The UNT Digital Library
Shocked and Stressed, Metals Get Stronger (open access)

Shocked and Stressed, Metals Get Stronger

People who know their way around metalworking are no doubt familiar with peening--using a ball-peen hammer to pound a piece of metal into shape and strengthen it against fatigue failure. For the past 50 years, an industrialized equivalent has been shot peening, in which metal or ceramic beads as large as marbles or as small as salt and pepper grains pneumatically bombard a metal surface. Laser peening, a process based on a superior laser technology developed at Lawrence Livermore, replaces the hammer blows and streams of beads with short blasts of laser light. The end result is a piece of metal with significantly improved performance. Lawrence Livermore and Metal Improvement Company, Inc., won a coveted R and D 100 Award for their laser-peening process in 1998 (see S and TR, October 1998, pp. 12-13). Since that time, they've been developing uses for the technology with a number of industries, including automotive, medical, and aerospace. They've also developed an offshoot technique--laser peenmarking{trademark}--which provides a way to easily and clearly identify parts with a mark that is extremely difficult to counterfeit. Another outgrowth is a new peen-forming technology that allows complex contouring of problematic thick metal components such as the thick sections …
Date: March 12, 2002
Creator: Hackel, L
System: The UNT Digital Library
Characterization of Vadose Zone Sediment: Uncontaminated RCRA Borehole Core Samples and Composite Samples (open access)

Characterization of Vadose Zone Sediment: Uncontaminated RCRA Borehole Core Samples and Composite Samples

The overall goal of the of the Tank Farm Vadose Zone Project, led by CH2M HILL Hanford Group, Inc., is to define risks from past and future single-shell tank farm activities. To meet this goal, CH2M HILL Hanford Group, Inc. asked scientists from Pacific Northwest National Laboratory to perform detailed analyses on vadose zone sediment from within the S-SX Waste Management Area. This report is the first in a series of four reports to present the results of these analyses. Specifically, this report contains all the geologic, geochemical, and selected physical characterization data collected on vadose zone sediment recovered from RCRA borehole bore samples and composite samples. Intact cores from two RCRA boreholes (299-W22-48 and 299-W22-50) near the SX Tank Farm and four, large-quantity grab samples from outcrop sediment on and off the Hanford Site were sampled to better understand the fate of contaminants in the vadose zone beneath underground storage tanks at the Hanford Site. Borehole and outcrop samples analyzed for this report are located outside the tank farms, and therefore may be considered standard or background samples from which to compare contaminated sediments within the tank farms themselves. This report presents our interpretation of the physical, chemical, and …
Date: February 12, 2002
Creator: Serne, R. Jeffrey; Bjornstad, Bruce N.; Schaef, Herbert T.; Williams, Bruce A.; Lanigan, David C.; Horton, Duane G. et al.
System: The UNT Digital Library
Evaluation of Cloud Parameterizations in a High Resolution Atmospheric General Circulation Model Using ARM Data (open access)

Evaluation of Cloud Parameterizations in a High Resolution Atmospheric General Circulation Model Using ARM Data

Typical state of the art atmospheric general circulation models used in climate change studies have horizontal resolution of approximately 300 km. As computing power increases, many climate modeling groups are working toward enhancing the resolution of global models. An important issue that arises when resolution of a model is changed is whether cloud and convective parameterizations, which were developed for use at coarser resolutions, will need to be reformulated or re-tuned. We propose to investigate this issue and specifically cloud statistics using ARM data. The data streams produced by highly instrumented sections of Cloud and Radiation Testbeds (CART) of ARM program will provide a significant aid in the evaluation of cloud and convection parameterization in high-resolution models. Recently, we have performed multiyear global-climate simulations at T170 and T239 resolutions, corresponding to grid cell sizes of 0.7{sup 0} and 0.5{sup 0} respectively, using the NCAR Community Climate Model. We have also a performed climate change simulation at T170. On the scales of a T42 grid cell (300 km) and larger, nearly all quantities we examined in T170 simulation agree better with observations in terms of spatial patterns than do results in a comparable simulation at T42. Increasing the resolution to T239 …
Date: April 12, 2002
Creator: Govindasamy, B & Duffy, P
System: The UNT Digital Library
Optimization of Hydroacoustic Deployments at John Day Dam (open access)

Optimization of Hydroacoustic Deployments at John Day Dam

This report describes short-term studies conducted in late November and early December 2001 to optimize hydroacoustic sampling techniques for John Day Dam before the 2002 fish passage efficiency (FPE) study. Knowledge gained in this study should significantly improve hydroacoustic sampling and the accuracy of estimates of fish passage at two locations that have presented problems in past studies. The spillway has been most problematic because many fish detected there were not entrained. Without correction, non-commitment of fish can result in multiple detections and overestimation of fish passage and FPE. Trash-rack-mounted, down-looking transducers for sampling unguided fish at a submerged traveling screen (STS) also have posed problems because the beam was aimed so far downstream that researchers had concerns about fish aspect and detectability. The deployments, aiming angles, and ping rates described here should eliminate all problems encountered in previous studies. This report describes hydroacoustic evaluations. The spill-bay deployment identified in this study should completely eliminate multiple detections of fish by limiting the sample volume for counting fish to the deep high-discharge volume adjacent to the gate. Results from testing of transducers deployed in a turbine intake with an STS suggest that, after testing in 2002, it may be possible to …
Date: November 12, 2002
Creator: Ploskey, Gene R.; Cook, Christopher B.; Titzler, P. Scott & Moursund, Russell A.
System: The UNT Digital Library
Connecting to the Internet Securely: Windows 2000 CIAC-2321 (open access)

Connecting to the Internet Securely: Windows 2000 CIAC-2321

As the threat to computer systems increases with the increasing use of computers as a tool in daily business activities, the need to securely configure those systems becomes more important. There are far too many intruders with access to the Internet and the skills and time to spend compromising systems to not spend the time necessary to securely configure a system. Hand-in-hand with the increased need for security are an increased number of items that need to be securely configured. Windows 2000 has about seven hundred security related policy settings, up from seventy two in Windows NT. While Windows 2000 systems are an extension of the Windows NT 4 architecture, there are considerable differences between these two systems, especially in terms of system and security administration. Operational policy, system security, and file security are other areas where Windows 2000 has expanded considerably beyond the domain model of Windows NT 4. The Windows NT 4 Domain model consists of domains of workstations that, with a single login, share resources and are administered together. The database of user settings and credentials resides in the domain server. Domains can trust other domains to expand the sharing of resources between users of multiple domains. …
Date: March 12, 2002
Creator: Orvis, W; Call, K & Dias, J
System: The UNT Digital Library
Characterization of Vadose Zone Sediment: Slant Borehole SX-108 in the S-SX Waste Management Area (open access)

Characterization of Vadose Zone Sediment: Slant Borehole SX-108 in the S-SX Waste Management Area

The overall goal of the Tank Farm Vadose Zone Project, led by CH2M HILL Hanford Group, Inc., is to define risks from past and future single-shell tank farm activities. To meet this goal, CH2M HILL Hanford Group, Inc., asked scientists from Pacific Northwest National Laboratory to perform detailed analyses on vadose zone sediment from within the S-SX Waste Management Area. This report is the fourth in a series of four reports to present the results of these analyses. Specifically, this fourth report contains all the geologic, geochemical, and selected physical characterization data collected on vadose zone sediment recovered from the slant borehole installed beneath tank 241-SX-108 (or simply SX-108 slant borehole). This report also presents our interpretation of the data in the context of determining the appropriate lithologic model, the vertical extent of contamination, the migration potential of the contaminants that still reside in the vadose zone, and the correspondence of the contaminant distribution in the borehole sediment in relationship to groundwater plumes in the aquifer proximate and downgradient from the SX Tank Farm.
Date: February 12, 2002
Creator: Serne, R. Jeffrey; Last, George V.; Schaef, Herbert T.; Lanigan, David C.; Lindenmeier, Clark W.; Ainsworth, Calvin C. et al.
System: The UNT Digital Library
Characterization of Vadose Zone Sediment: Borehole 41-09-39 in the S-SX Waste Management Area (open access)

Characterization of Vadose Zone Sediment: Borehole 41-09-39 in the S-SX Waste Management Area

The geology under the SX Tank Farm forms the framework through which the contaminants move and provides the basis with which to interpret and extrapolate the physical and geochemical properties that control the migration and distribution of contaminants. Of particular interest are the interrelationships between the coarser and finer-grained facies and the degree of contrast in their physical and geochemical properties. The vertical distribution of cesium-137, based on borehole gamma logging and the laboratory analysis of the sediment at borehole 41-09-39, suggest that much of the tank fluid that leaked from tanks SX-108, SX-109, SX-111, and SX-112 traveled within the coarse-grained Hanford formation H1 unit that is found between 67 and 88 feet below ground surface (bgs) at borehole 41-09-39. It is difficult to differentiate the known moisture content relationship with particle size (finer-grained material retains higher moisture contents) from excess moisture from leaked fluid. Thus, moisture content distribution did not give us a clear indication of the vertical extent of the plume. However, moisture content does help identify intervals that have been impacted by drilling operations. The pH values are not nearly as high as would be expected for tank liquor completely saturating sediment. Therefore, it would appear that …
Date: February 12, 2002
Creator: Serne, R. Jeffrey; Last, George V.; Schaef, Herbert T.; Lanigan, David C.; Lindenmeier, Clark W.; Ainsworth, Calvin C. et al.
System: The UNT Digital Library
Characterization of Vadose Zone Sediment: Borehole 299-W23-19 [SX -115] in the S-SX Waste Management Area. (open access)

Characterization of Vadose Zone Sediment: Borehole 299-W23-19 [SX -115] in the S-SX Waste Management Area.

The Tank Farm Vadose Zone Project is led by CH2M HILL Hanford Group, Inc. Their goals include defining risks from past and future single-shell tank farm activities, identifying and evaluating the efficacy of interim measures, and collecting geo-technical information and data. The purpose of these activities is to support future decisions made by the U.S. Department of Energy regarding near-term operations, future waste retrieval, and final closure activities for the single-shell tank Waste Management Areas. To help in this effort, CH2M HILL contracted with scientists at Pacific Northwest National Laboratory to analyze sediment samples collected from borehole 299-W23-19. The conclusions reached from this study support specific mechanisms influencing subsurface migration of contaminants. The mechanisms are supported by the distributions of contaminants beneath tank farms. These observations will help DOE and CH2M HILL identify and implement viable remediation and closure activities.
Date: February 12, 2002
Creator: Serne, R. Jeffrey; Schaef, Herbert T.; Bjornstad, Bruce N.; Lanigan, David C.; Gee, Glendon W.; Lindenmeier, Clark W. et al.
System: The UNT Digital Library
High Pressure Back up Air Piping Pressure Test (open access)

High Pressure Back up Air Piping Pressure Test

None
Date: March 12, 2002
Creator: Rucinski, Russell A.
System: The UNT Digital Library
Mineralogic Model (MM3.0) Analysis Model Report (open access)

Mineralogic Model (MM3.0) Analysis Model Report

The purpose of this report is to document the Mineralogic Model (MM), Version 3.0 (MM3.0) with regard to data input, modeling methods, assumptions, uncertainties, limitations and validation of the model results, qualification status of the model, and the differences between Version 3.0 and previous versions. A three-dimensional (3-D) Mineralogic Model was developed for Yucca Mountain to support the analyses of hydrologic properties, radionuclide transport, mineral health hazards, repository performance, and repository design. Version 3.0 of the MM was developed from mineralogic data obtained from borehole samples. It consists of matrix mineral abundances as a function of x (easting), y (northing), and z (elevation), referenced to the stratigraphic framework defined in Version 3.1 of the Geologic Framework Model (GFM). The MM was developed specifically for incorporation into the 3-D Integrated Site Model (ISM). The MM enables project personnel to obtain calculated mineral abundances at any position, within any region, or within any stratigraphic unit in the model area. The significance of the MM for key aspects of site characterization and performance assessment is explained in the following subsections. This work was conducted in accordance with the Development Plan for the MM (CRWMS M&O 2000). The planning document for this Rev. 00, …
Date: February 12, 2002
Creator: Lum, C.
System: The UNT Digital Library
Wafer-Bonded Internal Back-Surface Reflectors for Enhanced TPV Performance (open access)

Wafer-Bonded Internal Back-Surface Reflectors for Enhanced TPV Performance

This paper discusses recent efforts to realize GaInAsSb/GaSb TPV cells with an internal back-surface reflector (BSR). The cells are fabricated by wafer bonding the GaInAsSb/GaSb device layers to GaAs substrates with a dielectric/Au reflector, and subsequently removing the GaSb substrate. The internal BSR enhances optical absorption within the device while the dielectric layer provides electrical isolation. This approach is compatible with monolithic integration of series-connected TPV cells and can mitigate the requirements of filters used for front-surface spectral control.
Date: August 12, 2002
Creator: Wang, C. A.; Murphy, P. G.; O'Brien, P. W.; Shiau, D. A.; Anderson, A. C.; Liau, Z. L. et al.
System: The UNT Digital Library
Direct Energy Conversion Fission Reactor, Gaseous Core Reactor with Magnetohydrodynamic (MHD) Generator; Final Report - Part I and Part II (open access)

Direct Energy Conversion Fission Reactor, Gaseous Core Reactor with Magnetohydrodynamic (MHD) Generator; Final Report - Part I and Part II

This report focuses on the power conversion cycle and efficiency. The technical issues involving the ionization mechanisms, the power management and distribution and radiation shielding and safety will be discussed in future reports.
Date: November 12, 2002
Creator: Anghaie, Samim; Smith, Blair & Knight, Travis
System: The UNT Digital Library
Gene-Enzyme Relationships of Aromatic Amino Acid Biosynthesis in Higher Plants (open access)

Gene-Enzyme Relationships of Aromatic Amino Acid Biosynthesis in Higher Plants

Inhibition studies of amino acids in Nicotiana silvestris suspension cells gave clues to the difficulties for obtaining mutants deficient in post prephenate pathway proteins of aromatic amino acid biosynthesis (prephenate aminotransferase, arogenate dehydrogenase and arogenate dehydratase). Such mutants, if successfully obtained, would allow gene-enzyme relationships of aromatic amino acid proteins to be studied. We found that amino acids were inhibitory toward plant cell growth, and thus were unable to rescue analog resistant mutants. Toxicity of all amino acids toward exponentially dividing Nicotiana silvestris suspension cultured cells was monitored by following growth rates. Except for L-glutamine, all 19 protein amino acids inhibited cell growth. Inhibition of growth progressed to cell deterioration. Electron microscopy showed that amino acids triggered a state of cell shrinkage that eventually degenerated to total cellular disorganization. L-glutamine was not only an effective agent for prevention of amino acid toxicity, but enhanced the final growth yield. L-glutamine also was able to completely reverse inhibition effects in cells that had been in the slowed exponential phase. Two types of inhibition occurred and we have proposed that any amino acid inhibition that can be completely antagonized by L-glutamine be called ''general amino acid inhibition''. ''Specific amino acid inhibition'' resulting from …
Date: August 12, 2002
Creator: unknown
System: The UNT Digital Library
RESEARCH PROGRAM ON FRACTURED PETROLEUM RESERVOIRS (open access)

RESEARCH PROGRAM ON FRACTURED PETROLEUM RESERVOIRS

Numerical simulation of water injection in discrete fractured media with capillary pressure is a challenge. Dual-porosity models in view of their strength and simplicity can be mainly used for sugar-cube representation of fractured media. In such a representation, the transfer function between the fracture and the matrix block can be readily calculated for water-wet media. For a mixed-wet system, the evaluation of the transfer function becomes complicated due to the effect of gravity. In this work, they use a discrete-fracture model in which the fractures are discretized as one dimensional entities to account for fracture thickness by an integral form of the flow equations. This simple step greatly improves the numerical solution. Then the discrete-fracture model is implemented using a Galerkin finite element method. The robustness and the accuracy of the approach are shown through several examples. First they consider a single fracture in a rock matrix and compare the results of the discrete-fracture model with a single-porosity model. Then, they use the discrete-fracture model in more complex configurations. Numerical simulations are carried out in water-wet media as well as in mixed-wet media to study the effect of matrix and fracture capillary pressures.
Date: April 12, 2002
Creator: Firoozabadi, Abbas
System: The UNT Digital Library
NWCC Guidelines for Assessing the Economic Development Impacts of Wind Power (open access)

NWCC Guidelines for Assessing the Economic Development Impacts of Wind Power

OAK-B135 The primary objective of this study is to provide examples of thorough and consistent analysis and documentation of economic impacts from wind power development.
Date: February 12, 2002
Creator: Michael Taylor, Northwest Economic Associates Alan Fox, Northwest Economic Associates Jill Chilton, Northwest Economic Associates NWCC Economic Development Work Group Contributors Steve Clemmer, Lisa Daniels, Ed DeMeo, Rick Halet, Ron Lehr, Michael Milligan Vince Robinson
System: The UNT Digital Library
Imaging of Acoustically Coupled Oscillations Due to Flow Past a Shallow Cavity: Effect of Cavity Length Scale (open access)

Imaging of Acoustically Coupled Oscillations Due to Flow Past a Shallow Cavity: Effect of Cavity Length Scale

Flow-acoustic interactions due to fully turbulent inflow past a shallow axisymmetric cavity mounted in a pipe are investigated using a technique of high-image-density particle image velocimetry in conjunction with unsteady pressure measurements. This imaging leads to patterns of velocity, vorticity, streamline topology, and hydrodynamic contributions to the acoustic power integral. Global instantaneous images, as well as time-averaged images, are evaluated to provide insight into the flow physics during tone generation. Emphasis is on the manner in which the streamwise length scale of the cavity alters the major features of the flow structure. These image-based approaches allow identification of regions of the unsteady shear layer that contribute to the instantaneous hydrodynamic component of the acoustic power, which is necessary to maintain a flow tone. In addition, combined image analysis and pressure measurements allow categorization of the instantaneous flow patterns that are associated with types of time traces and spectra of the fluctuating pressure. In contrast to consideration based solely on pressure spectra, it is demonstrated that locked-on tones may actually exhibit intermittent, non-phase-locked images, apparently due to low damping of the acoustic resonator. Locked-on flow tones (without modulation or intermittency), locked-on flow tones with modulation, and non-locked-on oscillations with short-term, highly …
Date: December 12, 2002
Creator: Oshkai, P.; Geveci, M.; Rockwell, D. & Pollack, M.
System: The UNT Digital Library
Determination and correction of the linear lattice of the APS storage ring. (open access)

Determination and correction of the linear lattice of the APS storage ring.

The authors have created precise linear models of the storage ring in terms of beta functions for both low-emittance and high-emittance lattices. Using these models, the beta function beating corrections have been successfully applied. The lifetime was increased by 40% for the low-emittance lattice as a result of the corrections. The models allow the user to apply predictable and precise changes to the existing lattice. For example, after applying the beta function corrections, the beta-function changes exactly coincide with the changes predicted by the model. The generated machine model contains not only the real beta functions of the ring but it also provides Beam Position Monitors (BPM) gain calibrations. This could be useful for a number of applications that rely on the BPM readings. Unfortunately, one important task has not been accomplished. The excessive number of quadrupoles per unit phase advance does not allow them to determine the real gradients for every quadrupole. Work on correcting this shortfall will continue in the future. Among other future plans is use of the response matrix fit to characterize and correct both global and local linear coupling. The implementation of a coupling calculation is rather straightforward but requires additional programming.
Date: March 12, 2002
Creator: Sajaev, V. & Emery, L.
System: The UNT Digital Library
Chicago metropolitan area critical infrastructure protection program electric power disruption emergency preparedness drill March 5, 2002 summary and lessons learned. (open access)

Chicago metropolitan area critical infrastructure protection program electric power disruption emergency preparedness drill March 5, 2002 summary and lessons learned.

Since January 2000, the Metropolitan Mayors Caucus, the Chicago Department of Environment, and the U.S. Department of Energy Office of Critical Infrastructure Protection (now part of the Office of Energy Assurance) have been collaborating on the development and implementation of guidelines that municipal governments can use in preparing for electric power disruptions. On March 5, 2002 Commonwealth Edison (ComEd), the electric company serving the Chicago metropolitan area, held a drill to test its emergency preparedness procedures. ComEd invited three communities in the metropolitan area--Buffalo Grove, Oak Brook, Riverside--to participate in the drill as part of their own emergency planning efforts to respond to electric power disruptions. Although ComEd had held joint exercises with the City of Chicago, this was the first time that a cooperative exercise with the suburban communities was conducted. The Infrastructure Assurance Center of Argonne National Laboratory, under the sponsorship of the U.S. Department of Energy's Office of Energy Assurance helped facilitate the drill in the communities. A series of meetings involving ComEd, community controllers (who helped organize the drill but did not participate directly), and Argonne personnel was held to lay out the ground rules for the drill and determine how it would operate. Attachment 1 …
Date: April 12, 2002
Creator: Cirillo, D.
System: The UNT Digital Library
FEASIBILITY ANALYSIS FOR INSTALLING A CIRCULATING FLUIDIZED BED BOILER FOR COFIRING MULTIPLE BIOFUELS AND OTHER WASTES WITH COAL AT PENN STATE UNIVERSITY (open access)

FEASIBILITY ANALYSIS FOR INSTALLING A CIRCULATING FLUIDIZED BED BOILER FOR COFIRING MULTIPLE BIOFUELS AND OTHER WASTES WITH COAL AT PENN STATE UNIVERSITY

The Pennsylvania State University, under contract to the U.S. Department of Energy (DOE), National Energy Technology Laboratory (NETL) is performing a feasibility analysis on installing a state-of-the-art circulating fluidized bed (CFB) boiler and ceramic filter emission control device at Penn State's University Park campus for cofiring multiple biofuels and other wastes with coal, and developing a test program to evaluate cofiring multiple biofuels and coal-based feedstocks. Penn State currently operates an aging stoker-fired steam plant at its University Park campus and has spent considerable resources over the last ten to fifteen years investigating boiler replacements and performing life extension studies. This effort, in combination with a variety of agricultural and other wastes generated at the agricultural-based university and the surrounding rural community, has led Penn State to assemble a team of fluidized bed and cofiring experts to assess the feasibility of installing a CFB boiler for cofiring biomass and other wastes along with coal-based fuels. The objective of the project is being accomplished using a team that includes personnel from Penn State's Energy Institute, Office of Physical Plant, and College of Agricultural Sciences; Foster Wheeler Energy Services, Inc.; Parsons Energy and Chemicals Group, Inc.; and Cofiring Alternatives.
Date: July 12, 2002
Creator: Miller, Bruce G.; Miller, Sharon Falcone; Cooper, Robert; Donovan, Douglas; Gaudlip, John; Lapinsky, Matthew et al.
System: The UNT Digital Library
Die Casting Part Distortion: Prediction and Attenuation (open access)

Die Casting Part Distortion: Prediction and Attenuation

The goal of this research was to predict the part deformation and residual stresses after ejection from the die and cooling to room temperature. A finite element model was built to achieve this goal and several modeling techniques were investigated throughout this research. Die-casting is a very complex process and the researchers are faced with a large number of hard to solve physical problems when modeling the process. Several assumptions are made in our simulation model. The first significant assumption is the instantaneous cavity filling. This means that the cavity filling stage is not considered in our model. Considering the cavity filling stage increases the modeling complexity as a result of different flow patterns. expected in the shot sleeve, gate, runner and different cavity features. The flow of gas from the cavity through the vents is another problem that is ignored in our model as a result of this assumption. Our second assumption is that the cast metal has uniform temperature distribution inside the cavity, at the starting point of simulation. This temperature is assumed to be over liquidus limit, i.e. the solid fraction is 0.0% of the cast metal. The third assumption is due to ABAQUS (commercial software used …
Date: February 12, 2002
Creator: Dr, R. Allen Miller
System: The UNT Digital Library
Neutral Transport Simulations of Gas Puff Imaging Experiments on Alcator C-Mod (open access)

Neutral Transport Simulations of Gas Puff Imaging Experiments on Alcator C-Mod

Visible imaging of gas puffs has been used on the Alcator C-Mod tokamak to characterize edge plasma turbulence, yielding data that can be compared with plasma turbulence codes. Simulations of these experiments with the DEGAS 2 Monte Carlo neutral transport code have been carried out to explore the relationship between the plasma fluctuations and the observed light emission. By imposing two-dimensional modulations on the measured time-average plasma density and temperature profiles, we demonstrate that the spatial structure of the emission cloud reflects that of the underlying turbulence. However, the photon emission rate depends on the plasma density and temperature in a complicated way, and no simple scheme for inferring the plasma parameters directly from the light emission patterns is apparent. The simulations indicate that excited atoms generated by molecular dissociation are a significant source of photons, further complicating interpretation of the gas puff imaging results.Visibl e imaging of gas puffs has been used on the Alcator C-Mod tokamak to characterize edge plasma turbulence, yielding data that can be compared with plasma turbulence codes. Simulations of these experiments with the DEGAS 2 Monte Carlo neutral transport code have been carried out to explore the relationship between the plasma fluctuations and the …
Date: June 12, 2002
Creator: Stotler, D. P.; LaBombard, B.; Terry, J. L. & Zweben, S. J.
System: The UNT Digital Library
Higher temperature reactor materials workshop sponsored by the Department of Energy Office of Nuclear Energy, Science, and Technology (NE) and the Office of Basic Energy Sciences (BES). (open access)

Higher temperature reactor materials workshop sponsored by the Department of Energy Office of Nuclear Energy, Science, and Technology (NE) and the Office of Basic Energy Sciences (BES).

On March 18-21, 2002, the Department of Energy, Office of Nuclear Energy, Science, and Technology (NE) and the Office of Basic Energy Sciences (BES) sponsored a workshop to identify needs and opportunities for materials research aimed at performance improvements of structural materials in higher temperature reactors. The workshop focused discussion around the reactor concepts proposed as part of the Generation IV Nuclear Energy System Roadmap. The goal of the Generation IV initiative is to make revolutionary improvements in nuclear energy system design in the areas of sustainability, economics, safety and reliability. The Generation IV Nuclear Energy Systems Roadmap working groups have identified operation at higher temperature as an important step in improving economic performance and providing a means for nuclear energy to support thermochemical production of hydrogen. However, the move to higher operating temperatures will require the development and qualification of advanced materials to perform in the more challenging environment. As part of the process of developing advanced materials for these reactor concepts, a fundamental understanding of materials behavior must be established and the data-base defining critical performance limitations of these materials under irradiation must be developed. This workshop reviewed potential reactor designs and operating regimes, potential materials for application …
Date: August 12, 2002
Creator: Allen, T.; Bruemmer, S.; Kassner, M.; Odette, R.; Stoller, R.; Was, G. et al.
System: The UNT Digital Library