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Evaluation of a bi-directional aluminum honeycomb impact limiter design

Description: A 120 Ton shipping cask is being developed for the on-site shipment of dry spent fuel at the Idaho National Engineering Laboratory. Impact limiters were incorporated in the cask design to limit the inertial load of the package and its contents during the hypothetical 9-meter (30-foot) drop accident required by 10CFR71. The design process included: (1) a series of static and dynamic tests to determine the crush characteristics of the bi-directional aluminum honeycomb impact limiter material, (2) the development of an analytical model to predict the cask deceleration force as a function of impact limiter crush, and (3) a series of quarter scale model drop tests to qualify the analytical model. The scale model testing, performed at Sandia National Laboratory in Albuquerque, New Mexico, revealed several design aspects which should be considered in developing bi-directional aluminum honeycomb impact limiters and several other design aspects which should be considered for impact limiter designs in general.
Date: December 1, 1995
Creator: Doman, M.J.
Partner: UNT Libraries Government Documents Department

Coal log pipeline research at University of Missouri. 3rd quarterly report for 1995, July 1, 1995--September 30, 1995

Description: During this quarter (1/1/95-9/30/95), major progress has been made in the following areas of coal log pipeline research, development and technology transfer: (1) Conceptual design of a test machine based on hydraulic presses to mass-produce 5.4-inch-diameter coal logs for testing in a 6-inch-diameter pipeline has been completed. (2) Conceptual design of a rotary-press machine to produce 1.9-inch-diameter coal logs for testing in a 2-inch-diameter pipeline has also been completed. (3) It has been confirmed through experiments that molds with round-edge exit can make logs as good as those made with tapered exit. (4) Conducted a study to determine the effect of surface condition of mold and lubricants on the quality of coal logs. (5) Completed an evaluation of the effect of fiber (wood pulp) on coal log quality. (6) Prepared an apparatus for testing fast compaction of coal logs -- 2 second per log. (7) Compacted coal logs in a 5.3-inch-diameter mold. (8) Completed a preliminary study to assess vacuum and steam heating systems to enhance coal log production and quality. (9) Changed the small-scale-CLP-demo loop from a once-through system to a recirculating system. (10) Completed revision of CLP economic model and revised the 1993 report.
Date: December 31, 1995
Creator: Liu, H.
Partner: UNT Libraries Government Documents Department

A brief review of bacterial transport in natural porous media

Description: This report reviews advances in the descriptions of microbial transport processes. The advances can often be translated into technological advances for solute transport, with potential applicability to a number of subsurface concerns related to solutes. The processes involved in microbial transport include physically controlled processes, chemically controlled processes, and biologically controlled processes. The physical processes involved in the transport of microbes include advection, diffusion, dispersion, straining, filtration, and exclusion. Biomass removal by chemical reactions has received less attention, and included electrostatic attraction and hydrophobic sorption. In addition, microbiologic processes affecting the fate and transport of microbes in the subsurface include growth and decay; motility and chemotaxis; biological adhesion; and predation. Interdependencies among these processes arise through coupling, e.g., as multiscale mixing in heterogeneous environments affects nutrient availability (growth) and filtration velocities (attachment).
Date: December 1, 1995
Creator: Ginn, T.R.
Partner: UNT Libraries Government Documents Department

SeaRAM: an evaluation of the safety of RAM transport by sea

Description: SeaRAM is a multi-year Department of Energy (DOE) project designed to validate the safety of shipping radioactive materials (RAM) by sea. The project has an ultimate goal of developing and demonstrating analytic tools for performing comprehensive analyses to evaluate the risks to humans and the environment due to sea transport of plutonium, vitrified high-level waste (VHLW), and spent fuel associated with reprocessing and research reactors. To achieve this end, evaluations of maritime databases and structural an thermal analyses of particular severe collision and fire accidents have been and will continue to be conducted. Program management for SeaRAM is based at the DOE`s Office of Environmental Restoration. Technical activities for the project are being conducted at Sandia National Laboratories (SNL). Several private organizations are also involved in providing technical support, notably Engineering Computer Optecnomics, Inc. (ECO). The technical work performed for SeaRAM also supports DOE participation in an International Atomic Energy Agency (IAEA) Cooperative Research Program (CRP) entitled Accident Severity at Sea During Transport of Radioactive Material. This paper discusses activities performed during the first year of the project.
Date: December 31, 1995
Creator: McConnell, P.; Sorenson, K.B.; Carter, M.H.; Keane, M.P.; Keith, V.F. & Heid, R.J.
Partner: UNT Libraries Government Documents Department

Workshop on transport for a common ion driver

Description: This report contains research in the following areas related to beam transport for a common ion driver: multi-gap acceleration; neutralization with electrons; gas neutralization; self-pinched transport; HIF and LIF transport, and relevance to common ion driver; LIF and HIF reactor concepts and relevance to common ion driver; atomic physics for common ion driver; code capabilities and needed improvement.
Date: December 31, 1994
Creator: Olson, C.C.; Lee, E. & Langdon, B.
Partner: UNT Libraries Government Documents Department

Measurements of the diffusion of iron and carbon in single crystal NiAl using ion implantation and secondary ion mass spectrometry

Description: Classical diffusion measurements in intermetallic compounds are often complicated by low diffusivities or low solubilities of the elements of interest. Using secondary ion mass spectrometry for measurements over a relatively shallow spatial range may be used to solve the problem of low diffusivity. In order to simultaneously obtain measurements on important impurity elements with low solubilities, the authors have used ion implantation to supersaturate a narrow layer near the surface. Single crystal NiAl was implanted with either {sup 12}C or both {sup 56}Fe and {sup 12}C in order to investigate the measurement of substitutional (Fe) versus interstitial (C) tracer diffusion and the cross effect of both substitutional and interstitial diffusion. When C alone was implanted negligible diffusion was observed over the range of times and temperatures investigated. When both Fe and C were implanted together significantly enhanced diffusion of the C was observed, which is apparently associated with the movement of Fe. This supports one theory of dynamic strain aging in Fe alloys NiAl.
Date: December 31, 1998
Creator: Hanrahan, R.J. Jr.; Withrow, S.P. & Puga-Lambers, M.
Partner: UNT Libraries Government Documents Department

Optical assessment of large marine particles: development of an imaging and analysis system for quantifying large particle distributions and fluxes. Annual report, 1993-1994

Description: The central goal of DOE`s Ocean Margin Program (OMP) is to determine whether continental shelves are quantitatively significant in removing carbon dioxide from the atmosphere and isolating it via burial in sediments or exporting it to the open ocean (Program Announcement, 1991). A major component of the OMP will be to measure carbon flux on the shelf and across the shelf to the slope and open ocean. In the first round of OMP funding we proposed to develop an optical instrument package and the analytical techniques to measure a wide spectrum of the large aggregate population of particles in the shelf/slope environment. This particle population, encompassing the ``marine snow`` size particles (diameters > 0.5 mm), is thought to be the major pathway of material flux in the ocean (McCave, 1975; Asper, 1987; Walsh and Gardner, 1992). The overall objective of this proposal was to develop an instrument package and the analytical techniques to precisely measure a wide spectrum of the large aggregate population of particles in the shelf/slope environment at a rate sufficient to integrate the observed particle distributions into the coupled physical and biogeochemical models necessary to understand the shelf and slope as a system. We envisioned three stages of development of the instrument package: (1) design, assembly, and laboratory testing of all components and the package as a whole, (2) a short period of laboratory and field testing of the instrument package to determine the best operational parameters, and (3) operations within a framework of complementary analytical sampling such as an appropriate process study funded under the OMP. The first two stages were covered by this proposal. A renewal proposal follows to cover the third stage. 6 figs.
Date: December 31, 1994
Creator: Walsh, I. D. & Gardner, W. D.
Partner: UNT Libraries Government Documents Department

Impact of MCNP unresolved resonance probability-table treatment on uranium and plutonium benchmarks

Description: Versions of MCNP up through and including 4B have not accurately modeled neutron self-shielding effects in the unresolved resonance energy region. Recently, a probability-table treatment has been incorporated into a developmental version of MCNP. This paper presents MCNP results for a variety of uranium and plutonium critical benchmarks, calculated with and without the probability-table treatment.
Date: December 31, 1998
Creator: Mosteller, R.D. & Little, R.C.
Partner: UNT Libraries Government Documents Department

Electronic transport in unconventional superconductors

Description: The author investigates the electron transport coefficients in unconventional superconductors at low temperatures, where charge and heat transport are dominated by electron scattering from random lattice defects. He discusses the features of the pairing symmetry, Fermi surface, and excitation spectrum which are reflected in the low temperature heat transport. For temperatures {kappa}{sub B}T {approx_lt} {gamma} {much_lt} {Delta}{sub 0}, where {gamma} is the bandwidth of impurity induced Andreev states, certain eigenvalues become universal, i.e., independent of the impurity concentration and phase shift. Deep in the superconducting phase ({kappa}{sub B}T {approx_lt} {gamma}) the Wiedemann-Franz law, with Sommerfeld`s value of the Lorenz number, is recovered. He compares the results for theoretical models of unconventional superconductivity in high-{Tc} and heavy fermion superconductors with experiment. The findings show that impurities are a sensitive probe of the low-energy excitation spectrum, and that the zero-temperature limit of the transport coefficients provides an important test of the order parameter symmetry.
Date: December 31, 1998
Creator: Graf, M.J.
Partner: UNT Libraries Government Documents Department

Applications of the ARGUS code in accelerator physics

Description: ARGUS is a three-dimensional, electromagnetic, particle-in-cell (PIC) simulation code that is being distributed to U.S. accelerator laboratories in collaboration between SAIC and the Los Alamos Accelerator Code Group. It uses a modular architecture that allows multiple physics modules to share common utilities for grid and structure input., memory management, disk I/O, and diagnostics, Physics modules are in place for electrostatic and electromagnetic field solutions., frequency-domain (eigenvalue) solutions, time- dependent PIC, and steady-state PIC simulations. All of the modules are implemented with a domain-decomposition architecture that allows large problems to be broken up into pieces that fit in core and that facilitates the adaptation of ARGUS for parallel processing ARGUS operates on either Cray or workstation platforms, and MOTIF-based user interface is available for X-windows terminals. Applications of ARGUS in accelerator physics and design are described in this paper.
Date: December 31, 1993
Creator: Petillo, J. J.; Mankofsky, A.; Krueger, W. A.; Kostas, C.; Mondelli, A. A. & Drobot, A. T.
Partner: UNT Libraries Government Documents Department

Beam dynamics simulation of the Spallation Neutron Source linear accelerator

Description: The accelerating structure for Spallation Neutron Source (SNS) consists of a radio-frequency-quadrupole-linac (RFQ), a drift-tube-linac (DTL), a coupled-cavity-drift-tube-linac (CCDTL), and a coupled-cavity-linac (CCL). The linac is operated at room temperature. The authors discuss the detailed design of linac which accelerates an H{sup {minus}} pulsed beam coming out from RFQ at 2.5 MeV to 1000 MeV. They show a detailed transition from 402.5 MHz DTL with a 4 {beta}{lambda} structure to a CCDTL operated at 805 MHz with a 12 {beta}{lambda} structure. After a discussion of overall feature of the linac, they present an end-to-end particle simulation using the new version of the PARMILA code for a beam starting from the RFQ entrance through the rest of the linac. At 1000 MeV, the beam is transported to a storage ring. The storage ring requires a large ({+-}500-keV) energy spread. This is accomplished by operating the rf-phase in the last section of the linac so the particles are at the unstable fixed point of the separatrix. They present zero-current phase advance, beam size, and beam emittance along the entire linac.
Date: December 31, 1998
Creator: Takeda, H.; Billen, J.H. & Bhatia, T.S.
Partner: UNT Libraries Government Documents Department

Analysis and performance of adjacent-cell preconditioners for accelerating multidimensional transport calculations

Description: The formal development of the Adjacent-cell Preconditioner (AP) and its implementation in the TORT code are briefly reviewed. Based on earlier experience with diffusion type acceleration, and excellent results in slab geometry the reciprocal averaging formula is used to mix the preconditioner elements across material and mesh discontinuities. Numerical testing of the method employing the Burre Suite of Test Problems (BSTeP), a collection of 144 cases covering a wide range in parameter space, using AP, Partial Current Rebalance (PCR), and TWODANT`s Diffusion Synthetic Acceleration (DSA) is presented. While AP outperforms the other two methods for the majority of the cases included in BSTeP it consumes many more iterations than can be explained by spectral analysis of the homogeneous model problem in cases with sharp material discontinuity. In order to verify this undesirable behavior and explore potential remedies a model problem, the Periodic Horizontal Interface (PHI), is developed that permits discontinuity of nuclear properties and cell height across the interface. Fourier mode decomposition is applied to AP with the reciprocal averaging mixing formula for the PHI configuration and shown to possess a spectral radius that approaches unity as the material discontinuity gets larger. The question of whether an unconditionally stable AP exists for PHI is tackled and preliminary indications are negative. Novel preconditioners that have nontraditional cell-coupling schemes that remain stable in these regimes may have to be sought.
Date: December 31, 1996
Creator: Azmy, Y.Y.
Partner: UNT Libraries Government Documents Department

Particle filtration: An analysis using the method of volume averaging

Description: The process of filtration of non-charged, submicron particles is analyzed using the method of volume averaging. The particle continuity equation is represented in terms of the first correction to the Smoluchowski equation that takes into account particle inertia effects for small Stokes numbers. This leads to a cellular efficiency that contains a minimum in the efficiency as a function of the particle size, and this allows us to identify the most penetrating particle size. Comparison of the theory with results from Brownian dynamics indicates that the first correction to the Smoluchowski equation gives reasonable results in terms of both the cellular efficiency and the most penetrating particle size. However, the results for larger particles clearly indicate the need to extend the Smoluchowski equation to include higher order corrections. Comparison of the theory with laboratory experiments, in the absence of adjustable parameters, provides interesting agreement for particle diameters that are equal to or less than the diameter of the most penetrating particle.
Date: December 1, 1994
Creator: Quintard, M. & Whitaker, S.
Partner: UNT Libraries Government Documents Department

Particle filtration: A comparison between theory and experiment

Description: The process of filtration of non-charged, submicron particles represents an example of transport in homogeneous and heterogeneous porous media that can be analyzed using the method of volume averaging. In this article the authors develop the local volume averaged particle transport equation for a homogeneous filter and compare the results with experimental data. The particle continuity equation is represented in terms of the first correction to the Smoluchowski equation that takes into account particle inertia effects for small Stokes numbers. This leads to a cellular efficiency that contains a minimum in the efficiency as a function of the particle size, and this allows them to identify the most penetrating particle size. Comparison of the theory with experimental results indicates that the first correction to the Smoluchowski equation gives reasonable results for the most penetrating particle size and for smaller particles; however, results for larger particles clearly indicate the need to extend the Smoluchowski equation to include higher order corrections. The influence of local heterogeneities on the measured filter efficiency may account for some of the observed differences between theory and experiment.
Date: December 1, 1994
Creator: Quintard, M. & Whitaker, S.
Partner: UNT Libraries Government Documents Department

Direct calculation of leak path factors for highly compartmentalized buildings

Description: The large, highly compartmentalized configurations of buildings at many Department of Energy (DOE) facilities call the validity of traditional, simplistic methods for estimating contaminant leak path factors (LPFs) into question. Conversely, rigorous calculation of LPFs using detailed flow-field analysis computer codes is impractical for routine analysis. This paper describes a recent application of a rigorous, yet practical, method of calculating LPFs for the Chemical and Metallurgical Research (CMR) Facility at Los Alamos National Laboratory (LANL). The approach involves computer simulation of airborne contaminant transport using the MELCOR computer code. MELCOR is a general-purpose, fluid flow and aerosol transport analysis code originally developed by the US Nuclear Regulatory Commission to evaluate the release, transport, and deposition of radionuclides in nuclear reactor systems. However, the fundamental mathematical models in the code and the modular code architecture make it suitable to the CMR analysis.
Date: December 1, 1998
Creator: Leonard, M.T. & McClure, P.R.
Partner: UNT Libraries Government Documents Department

Polysaccharides and bacterial plugging. [Quarterly report], April 1--June 30, 1991

Description: This research seeks to model bacterial transport in porous media, to determine the importance of polysaccharides bridging as a retentive mechanism, and to identify key parameters that influence porous media plugging. Task 1 of the project is the determination of the grown kinetics of the Leuconostoc bacteria and how they are affected by the nutrient feed and surface effects. Task 2 will quantify the importance of polysaccharide production as a cell retention mechanism; and Task 3 is the elucidation of the rate of polysaccharide production and the combined effect that polysaccharide production and cell growth has upon plugging. Verification of the two parameter model, as presented in the past quarterly reports, was the focus of batch experiments. Three series of batch culture experiments, were conducted with varying yeast extract concentrations and with no saccharides. The specific rate constants for the cells of new inoculum are higher than the rates found from the past experiments using cultured cells as inoculum. This indicates that the cells used in the original experiments have undergone a phenotypic alteration. Thus, the model developed could not be verified and requires additional data. In future experiments, the growth of the inoculum will be controlled by minimizing the number of cell transfers before use in kinetic experiments. Two additional experimental series have been completed to determine the rate of cellular production of dextran. The first set of experiments consisted of two batch reactors containing 5 and 36 g/L of sucrose and 10 g/L of yeast extract in each.
Date: December 31, 1991
Creator: Fogler, H.S.
Partner: UNT Libraries Government Documents Department

Concentrations of a water soluble, gas-phase mercury species in ambient air: Results from measurements and modeling

Description: There are few reliable data on the speciation of Hg in ambient air, although this information is critical to understanding the fate of Hg once released from point sources. The water soluble species of Hg that are thought to exist in flue gases would be subject to far greater local removal rates than is elemental Hg vapor, but methods are lacing to quantify this species. The authors developed a method using refluxing mist chambers to measure the airborne concentrations of reactive gaseous mercury (RGM) in short-term samples under ambient conditions. The method exhibits an effective detection limit of 0.02 ng/m{sup 3} and a precision for ambient concentration levels of {+-}20--30%. Using a model that simulates atmospheric transport and fate of anthropogenic mercury emissions over the contiguous United States, the authors generated 24-hr RGM concentrations to compare to the measurement data. The average RGM concentrations measured with their mist chambers at sites in Tennessee (TN) and Indiana (IN) were 0.065 ng/m{sup 3} and 0.100 ng/m{sup 3}, respectively. These averages represent about 3% of total gaseous mercury (TGM), and RGM generally exceeds regional particulate Hg. The 24-hr model-simulated RGM concentration averages in the modeling grid cells representing TN and IN are 0.051 ng/m{sup 3} and 0.098 ng/m{sup 3} respectively, in good agreement with the data. The measured concentrations at the two sites exhibit weak positive correlations with temperature, solar radiation, O{sub 3}, SO{sub 2}, and TGM. These concentrations are high enough to suggest that RGM can play an important role in both wet and dry deposition on a regional scale.
Date: December 31, 1997
Creator: Lindberg, S. E.; Stratton, W. J.; Pai, P. & Allan, M. A.
Partner: UNT Libraries Government Documents Department

Gradient-Drive Diffusion of Multi-Atom Molecules Through Macromolecules and Membranes: LDRD 96-0021 Close-Out Report

Description: The goals of this Laboratory Directed Research and Development (LDRD) effort were to develop and prototype a new molecular simulation method and companion parallel algorithm able to model diffusion of multi-atom molecules through macromolecules under conditions of a chemical potential gradient. At the start of the project no such method existed, thus many important industrial and technological materials problems where gradient driven diffusion of multi-atom molecules is the predominant phenomenon were beyond the reach of molecular simulation (e.g. diffusion in polymers, a fundamental problem underlying polymer degradation in aging weapons).
Date: December 1, 1998
Creator: Ford, D.M.; Heffelfinger, G.S.; Martin, M.G. & Thompson, A.
Partner: UNT Libraries Government Documents Department

Numerical simulation of the Langevin equation for skewed turbulence

Description: In this paper the authors present a numerical method for the generalized Langevin equation of motion with skewed random forcing for the case of homogeneous, skewed turbulence. The authors begin by showing how the analytic solution to the Langevin equation for this case can be used to determine the relationship between the particle velocity moments and the properties of the skewed random force. They then present a numerical method that uses simple probability distribution functions to simulate the effect of the random force. The numerical solution is shown to be exact in the limit of infinitesimal time steps, and to be within acceptable error limits when practical time steps are used.
Date: December 1, 1994
Creator: Ermak, D. L. & Nasstrom, J. S.
Partner: UNT Libraries Government Documents Department

Beam Tools for Geant4 (User's Guide)

Description: Geant4 is a tool kit developed by a collaboration of physicists and computer professionals in the high energy physics field for simulation of the passage of particles through matter. The motivation for the development of the Beam Tools is to extend the Geant4 applications to accelerator physics. The Beam Tools are a set of C++ classes designed to facilitate the simulation of accelerator elements: r.f. cavities, magnets, absorbers, etc. These elements are constructed from Geant4 solid volumes like boxes, tubes, trapezoids, or spheers. There are many computer programs for beam physics simulations, but Geant4 is ideal to model a beam through a material or to integrate a beam line with a complex detector. There are many such examples in the current international High Energy Physics programs. For instance, an essential part of the R&D associated with the Neutrino Source/Muon Collider accelerator is the ionization cooling channel, which is a section of the system aimed to reduce the size of the muon beam in phase space. The ionization cooling technique uses a combination of linacs and light absorbers to reduce the transverse momentum and size of the beam, while keeping the longitudinal momentum constant. The MuCool/MICE (muon cooling) experiments need accurate simulations of the beam transport through the cooling channel in addition to a detailed simulation of the detectors designed to measure the size of the beam. The accuracy of the models for physics processes associated with muon ionization and multiple scattering is critical in this type of applications. Another example is the simulation of the interaction region in future accelerators. The high luminosity and background environments expected in the Next Linear Collider (NLC) and the Very Large Hadron Collider (VLHC) pose great demand on the detectors, which may be optimized by means of a simulation of the detector-accelerator interface.
Date: December 2, 2002
Creator: V.Daniel Elvira, Paul Lebrun and Panagiotis Spentzouris
Partner: UNT Libraries Government Documents Department

Test Plan and Test Specifications for Unloading LR-56 Waste at the 204-AR Waste Unloading Facility

Description: The LR-56 cask is an International Atomic Energy Agency (IAEA), type B (U) certified Medium to High Level Radioactive Liquid Waste Transport Cask. The LR-56 consists of a trailer equipped with the following component and systems: cubic meter lead shielded cask; Self-contained ventilation system including an air pressure/vacuum pump for cask loading and unloading; Waste temperature, level, leak detection, and other surveillance equipment; Control room for control of loading and unloading operations and waste surveillance; Hoist system for removing well caps on the cask; Power connection and control connections for operating the cask from a remote facility; The cask may be unloaded or loaded using either the onboard pressure/vacuum pump or by an external waste transfer pump. Rinse heads and connections allow the cask to be rinsed using supplied rinse water. The cask was designed to be vented using the LR-56 onboard ventilation system, which is connected to the cask via a hose through a penetration in the cask. Three wells located on the top of the cask, offer valved penetrations into the cask for venting, waste pumping, and rinsing. Other penetrations in the cask enable surveillance instrumentation to be used to monitor inside the cask. To date, the LR-56 cask system at the Hanford facility has not been used. Since the vessel has never received radioactive waste, the LR-56 is not yet a regulated system. It is desired to use the LR-56 cask to transport waste in calendar year 2000.
Date: December 3, 2000
Creator: BROWN, T.M.
Partner: UNT Libraries Government Documents Department

Final report for Grant No. DOE/DE-FG02-98ER14909: Experimental and modeling studies of nanometer aerosol filtration

Description: The primary objective is to perform a fundamental study of filtration of nanoparticles, and to obtain filtration knowledge necessary to design particle collection devices/systems for nanoparticle processing and for preventing nanoparticle emissions into the environment. The research covered a wide area relevant to nanoparticle filtration, under these main topics: (1) nanoparticle filtration and molecular dynamics simulation, (2) nanoparticle virtual impactor, (3) particle transport under low pressure, and (4) development of a high-throughput nanoparticle generator. A number of novel tools and numerical models have been developed under the DOE support.
Date: December 10, 2002
Creator: Pui, David Y. H. & Chen, Da-Ren
Partner: UNT Libraries Government Documents Department

Final Project Report

Description: This report provides a description of the main accomplishments of the EMSP funded research, including products such as conference presentations and publications (including those still in preparation). The purpose of this study was to better understand the chemical interactions between dissolved aqueous contaminants and carbonate minerals occurring as coatings on mineral grains in the vadose zone beneath the Hanford reserve. This information is important for construction of improved reactive transport models intended to predict the subsurface migration of contaminants. We made improvements to the hydrothermal atomic force microscope (HAFM) design to be used in this project. The original HAFM was built with funding from the U.S. DOE, Office of Basic Energy Sciences. Improvements include operating limits of 70 bars and 170 C, from an original limit of 12 bars and 150 C. This product is patented. We completed a series of studies of magnesite, MgCO3, because this mineral is structurally equivalent to calcite but reacts much more slowly, allowing us to study carbonate reactivity under pH conditions (i.e., low pH) that are much more problematic for studies of calcite but which are nevertheless relevant to in-situ conditions. We found that dissolving magnesite exhibits a dramatic change in step orientation, and therefore etch pit shape, as pH is lowered through 4.2 to 3 and 2. This change in step orientation is NOT accompanied by an increase in step velocity with decreasing pH. We also found that, after growing magnesite on a magnesite substrate, the newly grown magnesite dissolved much more readily than the underlying substrate magnesite, and exhibited far larger etch pit densities. This effect may have been related to the rate of growth or to the presence of an Fe impurity in the growth solutions. We studied the dissolution of magnesite and calcite (104) surfaces under a wider variety of ...
Date: December 12, 2003
Creator: Eggleston, Carrick M.
Partner: UNT Libraries Government Documents Department

STREAM II-V4: Revision for STREAM II-V3 to Allow Mouse-Driven Selection of Release Location from a Graphical User Interface

Description: STREAM II-V3 is an aqueous transport module of the Savannah River Site emergency response Weather INformation Display (WIND) system. Stream II-V3 predicts peak concentration and peak concentration arrival time at downstream locations for releases from the SRS facilities to the Savannah River. Fifteen pre-determined potential release locations from SRS facilities were built into the current STREAM II-V3 model. Therefore, STREAM II-V3 can not be used for situations in which release locations differ from the fifteen pre-determined locations. To eliminate this limitation, STREAM II-V3 was upgraded. The revised STREAM II-V4 allows users to select the release location anywhere along the specified SRS main streams or the Savannah River by mouse clicking on a map displayed on the computer monitor.
Date: December 18, 2002
Creator: Chen, K.F.
Partner: UNT Libraries Government Documents Department