Eight alternative methods for approximating salt creep and disposal room closure in a multiphase flow model of the Waste Isolation Pilot Plant (WIPP) were implemented and evaluated: Three fixed-room geometries three porosity functions and two fluid-phase-salt methods. The pressure-time-porosity line interpolation method is the method used in current WIPP Performance Assessment calculations. The room closure approximation methods were calibrated against a series of room closure simulations performed using a creep closure code, SANCHO. The fixed-room geometries did not incorporate a direct coupling between room void volume and room pressure. The two porosity function methods that utilized moles of gas as an independent parameter for closure coupling. The capillary backstress method was unable to accurately simulate conditions of re-closure of the room. Two methods were found to be accurate enough to approximate the effects of room closure; the boundary backstress method and pressure-time-porosity line interpolation. The boundary backstress method is a more reliable indicator of system behavior due to a theoretical basis for modeling salt deformation as a viscous process. It is a complex method and a detailed calibration process is required. The pressure lines method is thought to be less reliable because the results were skewed towards SANCHO results in simulations where the sequence of gas generation was significantly different from the SANCHO gas-generation rate histories used for closure calibration. This limitation in the pressure lines method is most pronounced at higher gas-generation rates and is relatively insignificant at lower gas-generation rates. Due to its relative simplicity, the pressure lines method is easier to implement in multiphase flow codes and simulations have a shorter execution time.
A long-term assessment of the Waste Isolation Pilot Plant (WIPP) repository performance must consider the impact of gas generation resulting from the corrosion and microbial degradation of the emplaced waste. A multiphase fluid flow code, TOUGH2/EOS8, was adapted to model the processes of gas generation, disposal room creep closure, and multiphase (brine and gas) fluid flow, as well as the coupling between the three processes. System response to gas generation was simulated with a single, isolated disposal room surrounded by homogeneous halite containing two anhydrite interbeds, one above and one below the room. The interbeds were assumed to have flow connections to the room through high-permeability, excavation-induced fractures. System behavior was evaluated by tracking four performance measures: (1) peak room pressure; (2) maximum brine volume in the room; (3) total mass of gas expelled from the room; and (4) the maximum gas migration distance in an interbed. Baseline simulations used current best estimates of system parameters, selected through an evaluation of available data, to predict system response to gas generation under best-estimate conditions. Sensitivity simulations quantified the effects of parameter uncertainty by evaluating the change in the performance measures in response to parameter variations. In the sensitivity simulations, a single parameter value was varied to its minimum and maximum values, representative of the extreme expected values, with all other parameters held at best-estimate values. Sensitivity simulations identified the following parameters as important to gas expulsion and migration away from a disposal room: interbed porosity; interbed permeability; gas-generation potential; halite permeability; and interbed threshold pressure. Simulations also showed that the inclusion of interbed fracturing and a disturbed rock zone had a significant impact on system performance.
Reconsolidation of crushed rock salt is a phenomenon of great interest to programs studying isolation of hazardous materials in natural salt geologic settings. Of particular interest is the potential for disaggregated salt to be restored to nearly an impermeable state. For example, reconsolidated crushed salt is proposed as a major shaft seal component for the Waste Isolation Pilot Plant (WIPP) Project. The concept for a permanent shaft seal component of the WIPP repository is to densely compact crushed salt in the four shafts; an effective seal will then be developed as the surrounding salt creeps into the shafts, further consolidating the crushed salt. Fundamental information on placement density and permeability is required to ensure attainment of the design function. The work reported here is the first large-scale compaction demonstration to provide information on initial salt properties applicable to design, construction, and performance expectations. The shaft seals must function for 10,000 years. Over this period a crushed salt mass will become less permeable as it is compressed by creep closure of salt surrounding the shaft. These facts preclude the possibility of conducting a full-scale, real-time field test. Because permanent seals taking advantage of salt reconsolidation have never been constructed, performance measurements have not been made on an appropriately large scale. An understanding of potential construction methods, achievable initial density and permeability, and performance of reconsolidated salt over time is required for seal design and performance assessment. This report discusses fielding and operations of a nearly full-scale dynamic compaction of mine-run WIPP salt, and presents preliminary density and in situ (in place) gas permeability results.
For a number of years, robotics researchers have exploited hierarchical representations of geometrical objects and scenes in motion-planning, collision-avoidance, and simulation. However, few general techniques exist for automatically constructing them. We present a generic, bottom-up algorithm that uses a heuristic clustering technique to produced balanced, coherent hierarchies. Its worst-case running time is O(N{sup 2}logN), but for non-pathological cases it is O(NlogN), where N is the number of input primitives. We have completed a preliminary C++ implementation for input collections of 3D convex polygons and 3D convex polyhedra and conducted simple experiments with scenes of up to 12,000 polygons, which take only a few minutes to process. We present examples using spheres and convex hulls as hierarchy primitives.
This paper describes two methods for controlling the surface of a liquid in an open container as it is being carried by a robot arm. Both methods make use of the fundamental mode of oscillation and damping of the liquid in the container as predicted from a boundary element model of the fluid. The first method uses an infinite impulse response filter to alter an acceleration profile so that the liquid remains level except for a single wave at the beginning and end of the motion. The motion of the liquid is similar to that of a simple pendulum. The second method removes the remaining two surface oscillations by tilting the container parallel to the beginning and ending wave. A double pendulum model is used to determine the trajectory for this motion. Experimental results of a FANUC S-800 robot moving a 230 mm diameter hemispherical container of water are presented.
This paper formulates an algorithm for trajectory generation for two robots cooperating to perform an assembly task. Treating the two robots as a single redundant system, this paper derives two Jacobian matrices which relate the joint rates of the entire system to the relative motion of the grippers with respect to one another. The advantage of this formulation over existing methods is that a variety of secondary criteria can be conveniently satisfied using motion in the null-space of the relative Jacobian. This paper presents methods for generating dual-arm joint trajectories which perform assembly tasks while at the same time avoiding obstacles and joint limits, and also maintaining constraints on the absolute position and orientation of the end-effectors.
Rock properties in volcanic units at Yucca Mountain are controlled largely by relatively deterministic geologic processes related to the emplacement, cooling, and alteration history of the tuffaceous lithologic sequence. Differences in the lithologic character of the rocks have been used to subdivide the rock sequence into stratigraphic units, and the deterministic nature of the processes responsible for the character of the different units can be used to infer the rock material properties likely to exist in unsampled regions. This report proposes a quantitative, theoretically justified method of integrating interpretive geometric models, showing the three-dimensional distribution of different stratigraphic units, with numerical stochastic simulation techniques drawn from geostatistics. This integration of soft, constraining geologic information with hard, quantitative measurements of various material properties can produce geologically reasonable, spatially correlated models of rock properties that are free from stochastic artifacts for use in subsequent physical-process modeling, such as the numerical representation of ground-water flow and radionuclide transport. Prototype modeling conducted using the GSLIB-Lynx Integration Module computer program, known as GLINTMOD, has successfully demonstrated the proposed integration technique. The method involves the selection of stratigraphic-unit-specific material-property expected values that are then used to constrain the probability function from which a material property of interest at an unsampled location is simulated.
To create an information system, we employ NIAM (Natural language Information Analysis Methodology). NIAM supports the goals of both the customer and the analyst completely understanding the information. We use the customer`s own unique vocabulary, collect real examples, and validate the information in natural language sentences. Examples are discussed from a successfully implemented information system.
The Burn Diagnostic and Laser Debridement project, CRADA Number SC93/01177 between Sandia and Wellman Laboratories of Photomedicine, will develop a prototype system for human trials of burn injury treatment using optical-based diagnostics and laser debridement. This quarterly progress report for July through September 1995 combines contributions from all team members on the project. The primary emphasis this quarter was completion of the Prototype Design Review. The review was conducted in two sessions, first at Sandia and second at Wellman. The objectives were to validate the requirements, compare the design intent with the stated requirements, critique the design, and conclude with a rating of acceptable, conditionally acceptable, or unacceptable. Although the design was rated conditionally acceptable at Sandia, the Wellman researchers felt too many issues were unresolved and therefore could not support that rating. The authors have initiated a plan to rapidly reach consensus on the remaining unresolved requirement issues so that construction of the Prototype II system can begin.
This report documents US Department of Energy (DOE)-funded activities that have adapted the US Navy`s Surface Towed Ordnance Locator System (STOLS) to meet DOE needs for a ``... better, faster, safer and cheaper ...`` system for characterizing inactive hazardous waste sites. These activities were undertaken by Sandia National Laboratories (Sandia), the Naval Research Laboratory, Geo-Centers Inc., New Mexico State University and others under the title of the Magnetometer Towed Array (MTA).
Traditional encryption, which protects messages from prying eyes, has been used for many decades. The present concepts of encryption are built from that heritage. Utilization of modern software-based encryption techniques implies much more than simply converting files to an unreadable form. Ubiquitous use of computers and advances in encryption technology coupled with the use of wide-area networking completely changed the reasons for utilizing encryption technology. The technology demands a new and extensive infrastructure to support these functions. Full understanding of these functions, their utility and value, and the need for an infrastructure, takes extensive exposure to the new paradigm. This paper addresses issues surrounding the establishment and operation of a key management system (i.e., certification authority) that is essential to the successful implementation and wide-spread use of encryption.
The reactor facilities at Sandia National Laboratories have hosted a number of reactors and critical experiments. A critical experiment is currently being done to support an ongoing investigation by the US Department of Energy of the consequences of taking fuel burnup into account in the design of spent fuel transportation packages. A series of experiments, collectively called the Spent Fuel Safety Experiment (SFSX), has been devised to provide integral benchmarks for testing computer-generated predictions of spent fuel behavior. A set of experiments is planned in which sections of unirradiated fuel rods are interchanged with similar sections of spent pressurized water reactor (PWR) fuel rods in a critical assembly. By determining the critical size of the arrays, one can obtain benchmark data for comparison with criticality safety calculations. The SFSX provides a direct measurement of the reactivity effects of spent PWR fuel using a well-characterized, spent fuel sample. The SFSX also provides an experimental measurement of the end-effect, i.e., the reactivity effect of the variation of the burnup profile at the ends of PWR fuel rods. The design of the SFSX is optimized to yield accurate benchmark measurements of the effects of interest, well above experimental uncertainties.
This paper defines a class of evolutionary algorithms called evolutionary pattern search algorithms (EPSAs) and analyzes their convergence properties. This class of algorithms is closely related to evolutionary programming, evolutionary strategie and real-coded genetic algorithms. EPSAs are self-adapting systems that modify the step size of the mutation operator in response to the success of previous optimization steps. The rule used to adapt the step size can be used to provide a stationary point convergence theory for EPSAs on any continuous function. This convergence theory is based on an extension of the convergence theory for generalized pattern search methods. An experimental analysis of the performance of EPSAs demonstrates that these algorithms can perform a level of global search that is comparable to that of canonical EAs. We also describe a stopping rule for EPSAs, which reliably terminated near stationary points in our experiments. This is the first stopping rule for any class of EAs that can terminate at a given distance from stationary points.
This paper examines the effects of relaxed synchronization on both the numerical and parallel efficiency of parallel genetic algorithms (GAs). We describe a coarse-grain geographically structured parallel genetic algorithm. Our experiments show that asynchronous versions of these algorithms have a lower run time than-synchronous GAs. Furthermore, we demonstrate that this improvement in performance is partly due to the fact that the numerical efficiency of the asynchronous genetic algorithm is better than the synchronous genetic algorithm. Our analysis includes a critique of the utility of traditional parallel performance measures for parallel GAs, and we evaluate the claims made by several researchers that parallel GAs can have superlinear speedup.
The preliminary criticality analysis that was done suggests that the possibility of achieving critical conditions cannot be easily ruled out without looking at the geochemical process of assembly or the dynamics of the operation of a critical assembly. The evaluation of a critical assembly requires an integrated, consistent approach that includes evaluating the following: (1) the alteration rates of the layers of the container and spent fuel, (2) the transport of fissile material or neutron absorbers, and (3) the assembly mechanisms that can achieve critical conditions. The above is a non-trivial analysis and preliminary work suggests that with the loading assumed, enough fissile mass will leach from the HEU multi-purpose canisters to support a criticality. In addition, the consequences of an unpressurized Oklo type criticality would be insignificant to the performance of an unsaturated, tuff repository.
Burnup verification measurements have been performed using the Fork system at the Oconee Nuclear Station of Duke Power Company, and at Arkansas Nuclear One (Units 1 and 2), operated by Energy Operations, Inc. Passive neutron and gamma-ray measurements on individual spent fuel assemblies were correlated with the reactor records for burnup, cooling time, and initial enrichment. The correlation generates an internal calibration for the system in the form of a power law determined by least squares fit to the neutron data. The average deviation of the reactor burnup records from the calibration determined from the measurements is a measure of the random error in the burnup records. The observed average deviations ranged from 2.2% to 3.5% for assemblies at the three reactor sites, indicating a high degree of consistency in the reactor records. Anomalous measurements were also observed but could be explained by the presence of neutron sources in the assemblies. The effectiveness of the Fork system for verification of reactor records is due to the sensitivity of the neutron yield to burnup, the self-calibration generated by a series of measurements, the redundancy provided by three independent detection systems, and the operational simplicity and flexibility of the design.
The properties and performance of a ceramic component is determined by a combination of the materials from which it was fabricated and how it was processed. Most ceramic components are manufactured by dry pressing a powder/binder system in which the organic binder provides formability and green compact strength. A key step in this manufacturing process is the removal of the binder from the powder compact after pressing. The organic binder is typically removed by a thermal decomposition process in which heating rate, temperature, and time are the key process parameters. Empirical approaches are generally used to design the burnout time-temperature cycle, often resulting in excessive processing times and energy usage, and higher overall manufacturing costs. Ideally, binder burnout should be completed as quickly as possible without damaging the compact, while using a minimum of energy. Process and computational modeling offer one means to achieve this end. The objective of this study is to develop an experimentally validated computer model that can be used to better understand, control, and optimize binder burnout from green ceramic compacts.
The Department of Energy`s Office of Materials Disposition (MD) is analyzing long-term storage and disposition options for fissile materials, preparing a Programmatic Environmental Impact Statement (PEIS), preparing for a Record of Decision (ROD) regarding this material, and conducting other related activities. A primary objective of this program is to support U.S. nonproliferation policy by reducing major security risks. Particular areas of concern are the acquisition of this material by unauthorized persons and preventing the reintroduction of the material for use in weapons. This paper presents some of the issues, definitions, and assumptions addressed by the Safeguards and Security Project Team in support of the Fissile Materials Disposition Program (FMDP). The discussion also includes some preliminary ideas regarding safeguards and security criteria that are applicable to the screening of disposition options.
The Department of Energy has defined a safeguards system to be an integrated system of physical protection, material accounting and material control subsystems designed to deter, prevent, detect, and respond to unauthorized possession, use, or sabotage of SNM. In practice, safeguards involve the development and application of techniques and procedures dealing with the establishment and continued maintenance of a system of activities. The system must also include administrative controls and surveillance to assure that the procedures and techniques of the system are effective and are being carried out. The control of nuclear material is critical to the safeguarding of nuclear materials within the United States. The U.S. Department of Energy includes as part of material control four functional performance areas. They include access controls, material surveillance, material containment and detection/assessment. This paper will address not only these areas but also the relationship between material control and other safeguards and security functions.
A series of static overpressurization tests of scale models of nuclear containment structures is being conducted by Sandia National Laboratories for the Nuclear Power Engineering Corporation of Japan and the U.S. Nuclear Regulatory Commission. At present, two tests are being planned: a test of a model of a steel containment vessel (SCV) that is representative of an improved, boiling water reactor (BWR) Mark II design; and a test of a model of a prestressed concrete containment vessel (PCCV). This paper discusses plans and the results of a preliminary investigation of the instrumentation of the PCCV model. The instrumentation suite for this model will consist of approximately 2000 channels of data to record displacements, strains in the reinforcing steel, prestressing tendons, concrete, steel liner and liner anchors, as well as pressure and temperature. The instrumentation is being designed to monitor the response of the model during prestressing operations, during Structural Integrity and Integrated Leak Rate testing, and during test to failure of the model. Particular emphasis has been placed on instrumentation of the prestressing system in order to understand the behavior of the prestressing strands at design and beyond design pressure levels. Current plans are to place load cells at both ends of one third of the tendons in addition to placing strain measurement devices along the length of selected tendons. Strain measurements will be made using conventional bonded foil resistance gages and a wire resistance gage, known as a {open_quotes}Tensmeg{close_quotes}{reg_sign} gage, specifically designed for use with seven-wire strand. The results of preliminary tests of both types of gages, in the laboratory and in a simulated model configuration, are reported and plans for instrumentation of the model are discussed.
The dynamic behavior of laser-accelerator flyers has been studied using high-speed streak imaging in combination with stop motion microphotography. With very thin targets, melting and plasma penetration of the flyer material occur in rapid sequence. The time delay from the onset of motion to flyer breakup increases with flyer thickness and decreasing incident energy. Flyer materials examined include pure aluminum (0.25-2.6 {mu}m thick) and composite targets (0.5-2.0 {mu}m thick) containing an insulating layer of aluminum oxide. While flyer breakup is observed in both types of material, the Al{sub 2}O{sub 3} barrier significantly delays the deleterious effects of deep thermal diffusion.
Charge-Induced Voltage Alteration (CIVA), Light-Induced Voltage Alteration, (LIVA), and Low Energy CIVA (LECIVA) are three new failure analysis imaging techniques developed to quickly localize defects on ICs. All three techniques utilize the voltage fluctuations of a constant current power supply as an electron or photon beam is scanned across an IC. CIVA and LECIVA yield rapid localization of open interconnections on ICs. LIVA allows quick localization of open-circuited and damaged semiconductor junctions. LIVA can also be used to image transistor logic states and can be performed from the backside of ICs with an infrared laser source. The physics of signal generation for each technique and examples of their use in failure analysis are described.
The solubility of Np(V) was measured in NaCl solutions ranging from 0.30 to 5.6 molal at room temperature ({approximately}21 {plus_minus} 2{degrees}C). Experiments were conducted from undersaturation and allowed to equilibrate in a CO{sub 2}-free environment for 37 days. The apparent solubility products varied with NaCl concentration and were between 10{sup -9} and 10{sup -8} mol{sup 2}{sm_bullet}L{sup -2}. Using the specific ion interaction theory (SIT), the log of the solubility product of NpO{sub 2}OH(am) at infinite dilution was found to be - 8.79 {plus_minus} 0.12. The interaction coefficient, {epsilon}(NpO{sub 2}{sup +} - Cl{sup -}), was found to be (0.08 {plus_minus} 0.05).
Citrate is among the organic anions that are expected to be present in the wastes planned for deposition in the Waste Isolation Pilot Plant repository. In this study, a solvent extraction method has been used to measure the stability constants of Thorium(IV)[Th(IV)] with citrate anions in aqueous solutions with (a) NaClO{sub 4} and (b) NaCl as the background electrolytes. The ionic strengths were varied up to 5 m (NaCl) and 14 m (NaClO{sub 4}). The data from the NaClO{sub 4} solutions at varying pH values were used to calculate the hydrolysis constants for formation of Th(OH){sup 3+} at the different ionic strengths.
The acid dissociation constants, pK{sub a}, and the stability constants for NpO{sub 2}{sup +} and UO{sub 2}{sup 2+} have been measured for certain organic ligands [acetate, {alpha}-hydroxyisobutyrate, lactate, ascorbate, oxalate, citrate, EDTA, 8-hydroxyquinoline, 1, 10-phenanthroline, and thenoyltrifluoroacetone] in 5 m (NaCl) ionic strength solution. The pK{sub a} values were determined by potentiometry or spectrometry. These methods, as well as solvent extraction with {sup 233}U and {sup 237}Np radiotracers, were used to measure the stability constants of the 1:1 and 1:2 complexes of dioxo cations. These constants were used to estimate the concentrations required to result in 10 % competition with hydrolysis in the 5 m NaCl solution. Such estimates are of value in assessing the solubility from radioactive waste of AnO{sub 2}{sup +} and AnO{sub 2}{sup 2+} in brine solutions in contact with nuclear waste in a salt-bed repository.
The complexation of Am(III) by oxalate has been investigated in solutions of NaClO{sub 4} up to 9.0 M ionic strength at 25{degrees}C. The dissociation constants of oxalic acid were determined by potentiometric titration, while the stability constants of the Am(III)-oxalate complexation were measured by the solvent extraction technique. A thermodynamic model was constructed to predict the apparent equilibrium constants at different ionic strengths by applying the Pitzer equation using parameters for the Na{sup +}-HOx{sup -}, Na{sup +}-Ox{sup -}, AmOx{sup +}-ClO{sub 4}{sup -}, and Na{sup +}-Am(Ox){sub 2}{sup -} interactions obtained by fitting the data.
Piezoelectric polymer stress gauges in copper fixtures were used with te Sandia 2.5-inch bore gas gun to obtain time-resolved pressure measurements for two polytetrafluoroethylene powders having significantly different particle morphologies. The powders had approximate average particle sizes of 534 microns and 28 microns, respectively, and scanning electron microscopy revealed differences in the appearances of representative particle surfaces. The range of input stresses was from 0.13 GPa to 2.81 GPa, and the initial densities were 57% of the solid density. The ``crush strength`` (pressure required to compress the porous compact to solid density) was close to 1.0 GPa for the coarse material as compared to 0.6 GPa for the finer material. At an input stress of about 0.6 GPa, the risetime of the propagated stress waves in the coarse material was approximately 240 nsec compared to 50 nsec for the finer material. These measurements show the strongly rate-dependent deformation of the powders and that particle morphology has a significant effect on the shock compression.
Sandia National Laboratory`s PV System Components Department performs comprehensive failure analysis of photovoltaic modules after extended field exposure at various sites around the world. A full spectrum of analytical techniques are used to help identify the causes of degradation. The techniques are used to make solder fatigue life predictions for PV concentrator modules, identify cell damage or current mismatch, and measure the adhesive strength of the module encapsulant.
The Manufacturing Technologies Center is an integral part of Sandia National Laboratories, a multiprogram engineering and science laboratory, operated for the Department of Energy (DOE) with major facilities at Albuquerque, New Mexico, and Livermore, California. Our Center is at the core of Sandia`s Advanced Manufacturing effort which spans the entire product realization process.
We present two new techniques that enhance conventional focused ion beam (FIB) system capabilities for integrated circuit (IC) analysis: in situ electrical biasing and voltage contrast imaging. We have used in situ electrical biasing to enable a number of advanced failure analysis applications including (1) real time evaluation of device electrical behavior during milling and deposition, (2) verification of IC functional modifications without removal from the FIB system, and (3) ultraprecision control for cross sectioning of deep submicron structures, such as programmed amorphous silicon antifuses. We have also developed FIB system voltage contrast imaging that can be used for a variety of failure analysis applications. The use of passive voltage contrast imaging for defect localization and for navigation on planarized devices will be illustrated. In addition, we describe new, biased voltage contrast imaging techniques and provide examples of their application to the failure analysis of complex ICs. We discuss the necessary changes in system operating parameters to perform biased voltage contrast imaging.
In fabricating lead zirconate titanate (PZT) films for nonvolatile memories and decoupling capacitors, various deposition methods have been investigated. Each can produce films with acceptable dielectric and ferroelectric properties, but sol-gel methods offer excellent control of film stoichiometry and coating uniformity. The sol-gel approaches for PZT film fabrication fall into two categories: processes that use 2-methoxyethanol as a solvent, and processes that use chelating agents, such as acetic acid, for reducing the hydrolysis sensitivity of the alkoxide compounds. Due to concerns about the toxicity of 2-methoxyethanol, we have concentrated on the second category. It was found that, in addition to reducing the hydrolysis sensitivity, the chelating agents serves to define the processing behavior of the films: film consolidation after deposition and densification and crystallization during heat treatment. This paper discusses the relations between precursor structure (reactions between chelating agents and the metal alkoxide starting reagents) and film consolidation, densification, and crystallization.
A mathematical formulation is presented for describing the transport of air, water, NAPL, and energy through porous media. The development follows a continuum mechanics approach. The theory assumes the existence of various average macroscopic variables which describe the state of the system. Balance equations for mass and energy are formulated in terms of these macroscopic variables. The system is supplemented with constitutive equations relating fluxes to the state variables, and with transport property specifications. Specification of phase equilibrium criteria, various mixing rules and thermodynamic relations completes the system of equations. A numerical simulation scheme based on finite-differences is described.
DOE has made a commitment to compliance with all applicable environmental regulatory requirements. In this respect, it is important to consider and design all tritium supply alternatives so that they can comply with these requirements. The management of waste is an integral part of this activity and it is therefore necessary to estimate the quantities and specific wastes that will be generated by all tritium supply alternatives. A thorough assessment of waste streams includes waste characterization, quantification, and the identification of treatment and disposal options. The waste assessment for APT has been covered in two reports. The first report was a process waste assessment (PWA) that identified and quantified waste streams associated with both target designs and fulfilled the requirements of APT Work Breakdown Structure (WBS) Item 5.5.2.1. This second report is an expanded version of the first that includes all of the data of the first report, plus an assessment of treatment and disposal options for each waste stream identified in the initial report. The latter information was initially planned to be issued as a separate Waste Treatment and Disposal Options Assessment Report (WBS Item 5.5.2.2).
Simulations with finite element models of well controlled impact experiments with x-cut quartz gauges have been performed with the transient electromechanics code SUBWAY. Comparisons of measured gauge output current with calculated output current were made for four fully-electroded gauge configurations, involving two different can spacings and potting materials. The observed good agreement between measured and calculated currents provides a basis for confidence in the basic capabilities of the code.
Given the low cost of petroleum crude, direct coal liquefaction is still not an economically viable process. The DOE objectives are to further reduce the cost of coal liquefaction to a more competitive level. In this project the primary focus is on the use of low-rank coal feedstocks. A particular strength is the use of process-derived liquids rather than model compound solvents. The original concepts are illustrated in Figure 1, where they are shown on a schematic of the Wilsonville pilot plant operation. Wilsonville operating data have been used to define a base case scenario using run {number_sign}263J, and Wilsonville process materials have been used in experimental work. The CAER has investigated: low severity CO pretreatment of coal for oxygen rejection, increasing coal reactivity and mg inhibiting the propensity for regressive reactions; the application of more active. Low-cost Fe and Mo dispersed catalysts; and the possible use of fluid coking for solids rejection and to generate an overhead product for recycle. CONSOL has investigated: oil agglomeration for coal ash rejection, for the possible rejection of ash in the recycled resid, and for catalyst addition and recovery; and distillate dewaxing to remove naphthenes and paraffins, and to generate an improved quality feed for recycle distillate hydrogenation. At Sandia, research has been concerned with the production of active hydrogen donor distillate solvent fractions produced by the hydrogenation of dewaxed distillates and by fluid coking via low severity reaction with H{sub 2}/CO/H{sub 2}O mixtures using hydrous metal oxide and other catalysts.
A stochastic representation of the lithologic units and associated hydrogeologic parameters of the potential high-level nuclear waste repository are developed for use in performance-assessment calculations, including the Total-System Performance Assessment for Yucca Mountain-SNL Second Iteration (TSPA-1993). A simplified lithologic model has been developed based on the physical characteristics of the welded and nonwelded units at Yucca Mountain. Ten hydrogeologic units are developed from site-specific data (lithologic and geophysical logs and core photographs) obtained from the unsaturated and saturated zones. The three-dimensional geostatistical model of the ten hydrogeologic units is based on indicator-coding techniques and improves on the two-dimensional model developed for TSPA91. The hydrogeologic properties (statistics and probability distribution functions) are developed from the results of laboratory tests and in-situ aquifer tests or are derived through fundamental relationships. Hydrogeologic properties for matrix properties, bulk conductivities, and fractures are developed from existing site specific data. Extensive data are available for matrix porosity, bulk density, and matrix saturated conductivity. For other hydrogeologic properties, the data are minimal or nonexistent. Parameters for the properties are developed as beta probability distribution functions. For the model units without enough data for analysis, parameters are developed as analogs to existing units. A relational, analytic approach coupled with bulk conductivity parameters is used to develop fracture parameters based on the smooth-wall-parallel-plate theory. An analytic method is introduced for scaling small-core matrix properties to the hydrogeologic unit scales.
Burnup verification measurements have been performed using the Fork system at Arkansas Nuclear One, Units 1 and 2, operated by Energy Operations, Inc. Passive neutron and gamma-ray measurements on individual spent fuel assemblies were correlated with the reactor records for burnup, cooling time, and initial enrichment. The correlation generates an internal calibration for the system in the form of a power law determined by a least squares fit to the neutron data. The values of the exponent in the power laws were 3.83 and 4.35 for Units 1 and 2, respectively. The average deviation of the reactor burnup records from the calibration determined from the measurements is a measure of the random error in the burnup records. The observed average deviations were 2.7% and 3.5% for assemblies at Units 1 and 2, respectively, indicating a high degree of consistency in the reactor records. Two non-standard assemblies containing neutron sources were studied at Unit 2. No anomalous measurements were observed among the standard assemblies at either Unit. The effectiveness of the Fork system for verification of reactor records is due to the sensitivity of the neutron yield to burnup, the self-calibration generated by a series of measurements, the redundancy provided by three independent detection systems, and the operational simplicity and flexibility of the design.
A pair of charge carriers can be bound within a common potential well produced by displacing atoms from their carrier-free equilibrium positions. These two self-trapped carriers together with the associated atomic-displacement pattern is referred to as a bipolaron. If the self-trapped carriers` wavefunction is primarily confined to a single structural unit (atom, bond or molecule), the bipolaron is termed small. If however the self-trapped carriers` wavefunction extends over multiple structural units, the bipolaron is called large. Small bipolarons form in crystals if the energy lowering due to the carriers` self-trapping exceeds the electronic-transfer energy associated with an electronic carrier`s intersite motion. Small-polaron and -bipolaron formation is also often induced by disorder. Interest in bipolarons focuses on situations in which they are energetically stable with respect to dissociating into two individual carriers. Stability is achieved when the additional lowering of the atomic-displacement-related energy arising from two carriers sharing a common site overwhelms their mutual Coulomb repulsion. Self-trapped carriers only move when the positions of the atoms whose displacements produce self-trapping change. When atoms move so as to shift small-polaronic self-trapped carriers between adjacent sites, changes of the self-trapped carriers` energies always exceed their intersite electronic transfer energy. Since small-polaronic self-trapped carriers thereby lose coherence as they move, their transport is described as hopping incoherently between localized states. This report discusses the electronic structure of boron carbides and describes features that make them ideal for studying small bipolaron hopping. The effect on conductivity is discussed.
This paper is written to document the SURFSCAN program. A large section of the code is devoted to error recovery. The heavy emphasis on error recovery allows unattended operation for extended periods. By combining error recovery with the use of control files, SURFSCAN has been operated for periods of several days with no operator intervention. At this time, the Surface Profilometer is a useful and productive tool in the Rock Mechanics Laboratory at Sandia National Laboratories/New Mexico. In the Rock Mechanics Laboratory we have been conducting studies of the normal and shear mechanical behavior of fractures and the flow of fluid through fractured rock formations. To estimate these properties, we need to know the average aperture size and surface texture of a fracture. These data may be obtained from surface profiles of mating pieces of rock. By scanning corresponding regions on two mating surfaces, the aperture size may be easily determined.
A fiberglass-reinforced plastic (FRP) pressure vessel containing sulfuric acid failed catastrophically in service. Preliminary investigations ruled out failure due to sabotage and chemical or mechanical overpressure. Subsequent examination of the fiber fracture surfaces and measurements of mirror radii indicated that fiber failure had occurred at stresses significantly below the fibers` expected strength. Further examination by scanning electron microscopy and energy dispersive spectroscopy indicated that the glass fibers had been exposed to sulfuric acid, a reagent that corrodes this type of glass and degrades its strength. Finite element analysis indicated stresses in an exposed region of the vessel that exceeded the strengths of the FRP during normal vessel operation. Numerous cracks were detected in this region using a vicinal optical illumination technique. We concluded that vessel failure was caused by progressive degradation and rupture of fibers starting at the outer surface of the FRP and extending inwards and laterally, until a crack of critical size was produced.
This report summarizes Sandia National Laboratories` participation in the fire modeling activities for the German Heiss Dampf Reaktor (HDR) containment building, under the sponsorship of the United States Nuclear Regulatory Commission. The purpose of this report is twofold: (1) to summarize Sandia`s participation in the HDR fire modeling efforts and (2) to summarize the results of the international fire modeling community involved in modeling the HDR fire tests. Additional comments, on the state of fire modeling and trends in the international fire modeling community are also included. It is noted that, although the trend internationally in fire modeling is toward the development of the more complex fire field models, each type of fire model has something to contribute to the understanding of fires in nuclear power plants.
This 1994 report contains data from routine radiological and nonradiological environmental monitoring activities. Summaries of significant environmental compliance programs in progress, such as National Environmental Policy Act documentation, environmental permits, environmental restoration, and various waste management programs for Sandia National Laboratories in Albuquerque, New Mexico, are included. The maximum off-site dose impact from air emissions was calculated to be 1.5 x 10{sup -4} millirem. The total population within a 50-mile radius of Sandia National Laboratories/New Mexico received an estimated collective dose of 0.012 person-rem during 1994 from the laboratories` operations. This report is prepared for the U.S. Department of Energy in compliance with DOE Order 5400.1.
A processed quartz sand (Wedron 510), mined from the St. Peter sandstone, has been characterized by a variety of chemical and physical methods for use as a reference porous media in transport model validation experiments. Wedron 510 sand was used in an intermediate-scale experiment involving migration of Ni, Li and Br through a 6-m high x 3-m diameter caisson. Ni and Li adsorption/desorption, and Li/Ni site-competition experiments yielded information on the importance of the trace mineral phases to adsorption of Li and Ni by the sand. The presence of an iron hydroxide coating similar to goethite on the sand grains is suggested by visual observation and leaching experiments. Kaolinite was identified by SEM and XRD as a significant trace mineral phase in the sand and occurs as small particles coating the sand grains. Quartz, the predominant constituent of the sand by weight, does not appear to contribute significantly to the adsorption properties of the sand. Qualitatively, the adsorption properties of the sand can be adequately modeled as a two-mineral system (goethite and kaolinite). The studies described in this report should provide a basis for understanding transport of Ni, Li and Br through porous media similar to the reference sand. Techniques were developed for obtaining parameter values for surface complexation and kinetic adsorption models for the sand and its mineral components. These constants can be used directly in coupled hydrogeochemical transport codes. The techniques should be useful for characterization of other natural materials and elements in high-level nuclear waste in support of coupled hydrogeochemical transport calculations for Yucca Mountain.
In this paper we apply a ``dual-transistor border-trap`` (DTBT) technique that combines high-frequency charge-pumping and lower-frequency threshold-voltage measurements to estimate bulk-oxide-trap, interface-trap, and border-trap densities in irradiated MOS transistors. This method takes advantage of the different time scales in which interface traps and border traps exchange charge with the Si to obtain an estimate of the density of faster border traps often mistaken for interface traps. Effects of slower border traps are also inferred from changes in the ``bulk`` oxide-trap charge density through switched-bias annealing. To our knowledge, this is the first time fast and slow border-trap effects have been separated quantitatively in MOS devices. Possible microstructures for fast and slow border traps are suggested.
The production of positive lithium ions using a lithium-fluoride-coated stainless steel anode in the particle beam fusion accelerator PBFA II is considered from both the experimental and theoretical points of view. It is concluded that the mechanism of Li{sup +} ion production is electric field desorption from the tenth-micron-scale crystallites which compose the columnar growth of the LiF thin film. The required electric field is estimated to be of the order of 5 MV/cm. An essential feature of the mechanism is that the crystallites are rendered electronically conducting through electron-hole pair generation by MeV electron bombardment of the thin film during the operation of the diode. It is proposed that the ion emission mechanism is an electronic conductivity analogue to that discovered by Rollgen for lithium halide crystallites which were rendered ionically conducting by heating to several hundred degrees Celsius. Since an electric field desorption mechanism cannot operate if a surface flashover plasma has formed and reduced the anode electric field to low values, the possibility of flashover on the lithium fluoride coated anode of the PBFA II Li{sup +} ion source is studied theoretically. It is concluded with near certainty that flashover does not occur.
Two-dimensional, heterogeneous, spatially correlated models of thermal conductivity and bulk density have been created for a representative, east-west cross section of Yucca Mountain, Nevada, using geostatistical simulation. The thermal conductivity models are derived from spatially correlated, surrogate material-property models of porosity, through a multiple linear-regression equation, which expresses thermal conductivity as a function of porosity and initial temperature and saturation. Bulk-density values were obtained through a similar, linear-regression relationship with porosity. The use of a surrogate-property allows the use of spatially much-more-abundant porosity measurements to condition the simulations. Modeling was conducted in stratigraphic coordinates to represent original depositional continuity of material properties and the completed models were transformed to real-world coordinates to capture present-day tectonic tilting and faulting of the material-property units. Spatial correlation lengths required for geostatistical modeling were assumed, but are based on the results of previous transect-sampling and geostatistical-modeling work.
The Mixed Waste Landfill Integrated Demonstration was tasked with demonstrating innovative technologies for the cleanup of chemical and mixed waste landfills that are representive of sites occurring throughout the DOE complex and the nation. The SEAMIST{trademark} inverting membrane deployment system has been used successfully at the Mixed Waste Landfill Integrated Demonstration (MWLID) for multipoint vapor sampling, pressure measurement, permeability measurement, sensor integration demonstrations, and borehole lining. Several instruments were deployed inside the SEAMIST{trademark}-lined boreholes to detect metals, radionuclides, moisture, and geologic variations. The liner protected the instruments from contamination, maintained support of the uncased borehole wall, and sealed the total borehole from air circulation. Recent activities included the installation of three multipoint vapor sampling systems and sensor integration systems in 100-foot-deep vertical boreholes. A long term pressure monitoring program has recorded barometric pressure effects at depth with relatively high spatial resolution. The SEAMIST{trademark} system has been integrated with a variety of hydrologic and chemical sensors for in-situ measurements, demonstrating its versatility as an instrument deployment system that allows easy emplacement and removal. Standard SEAMIST{trademark} vapor sampling systems were also integrated with state-of-the-art volatile organic compound analysis technologies. The results and status of these demonstration tests are presented.
One of the primary factors that influences our predictions of host-rock thermal response within a high level waste repository is how the waste stream`s represented in the models. In the context of thermal modeling, waste stream refers to an itemized listing of the type (pressurized-water or boiling-water reactor), age, burnup, and enrichment of the spent nuclear fuel assemblies entering the repository over the 25-year emplacement phase. The effect of package-by-package variations in spent fuel characteristics on predicted repository thermal response is the focus of this report. A three-year portion of the emplacement period was modeled using three approaches to waste stream resolution. The first assumes that each package type emplaced in a given year is adequately represented by average characteristics. For comparison, two models that explicitly account for each waste package`s individual characteristics were run; the first assuming a random selection of packages and the second an ordered approach aimed at locating the higher power output packages toward the center of the emplacement area. Results indicate that the explicit representation of packages results in hot and cold spots that could have performance assessment and design implications. Furthermore, questions are raised regarding the representativeness of average characteristics with respect to integrated energy output and the possible implications of a mass-based repository loading approach.
The response of underground structures and transportation facilities under various external loadings and environments is critical for human safety as well as environmental protection. Since quasi-brittle materials such as concrete and rock are commonly used for underground construction, the constitutive modeling of these engineering materials, including post-limit behaviors, is one of the most important aspects in safety assessment. From experimental, theoretical, and computational points of view, this report considers the constitutive modeling of quasi-brittle materials in general and concentrates on concrete in particular. Based on the internal variable theory of thermodynamics, the general formulations of plasticity and damage models are given to simulate two distinct modes of microstructural changes, inelastic flow and degradation of material strength and stiffness, that identify the phenomenological nonlinear behaviors of quasi-brittle materials. The computational aspects of plasticity and damage models are explored with respect to their effects on structural analyses. Specific constitutive models are then developed in a systematic manner according to the degree of completeness. A comprehensive literature survey is made to provide the up-to-date information on prediction of structural failures, which can serve as a reference for future research.
The Verification and Monitoring Options Study Project (VAMOS) was established to identify high-priority options for future vadose-zone environmental research in the areas of in-situ remediation monitoring, post-closure monitoring, and containment emplacement and verification monitoring. VAMOS examined projected needs not currently being met with applied technology in order to develop viable monitoring and verification research options. The study emphasized a compatible systems approach to reinforce the need for utilizing compatible components to provide user friendly site monitoring systems. To identify the needs and research options related to vadose-zone environmental monitoring and verification, a literature search and expert panel forums were conducted. The search included present drivers for environmental monitoring technology, technology applications, and research efforts. The forums included scientific, academic, industry, and regulatory environmental professionals as well as end users of environmental technology. The experts evaluated current and future monitoring and verification needs, methods for meeting these needs, and viable research options and directions. A variety of high-priority technology development, user facility, and technology guidance research options were developed and presented as an outcome of the literature search and expert panel forums.
Groundwater travel time (GWTT) calculations will play an important role in addressing site-suitability criteria for the potential high-level nuclear waste repository at Yucca Mountain,Nevada. In support of these calculations, Preliminary assessments of the candidate codes and models are presented in this report. A series of benchmark studies have been designed to address important aspects of modeling flow through fractured media representative of flow at Yucca Mountain. Three codes (DUAL, FEHMN, and TOUGH 2) are compared in these benchmark studies. DUAL is a single-phase, isothermal, two-dimensional flow simulator based on the dual mixed finite element method. FEHMN is a nonisothermal, multiphase, multidimensional simulator based primarily on the finite element method. TOUGH2 is anon isothermal, multiphase, multidimensional simulator based on the integral finite difference method. Alternative conceptual models of fracture flow consisting of the equivalent continuum model (ECM) and the dual permeability (DK) model are used in the different codes.
To assess the influence of mountain-scale thermal property model variations on predicted host-rock thermal response, a series of heat conduction calculations were run using a representative two-dimensional cross section of Yucca Mountain. The effects of modeled geologic structure were evaluated through comparisons of results from a single-material, homogeneous model with those from a uniformly layered model, a discontinuous sloping-layered model, and a geo-statistical realization of thermal properties. Comparisons indicate that assumed geologic structure can result in up to a 24{degrees}C difference in predicted temperature response. Further, thermal simulations of the method used to analyze geostatistical realizations of thermal properties shows promise as an efficient means of capturing geologic structure without the complexities of intricate finite element meshing. The functional representation of two thermal property models were also investigated. The first examines the effect of using a weighting scheme to define properties for a single, homogenous material model. The second investigates the impact of thermal property temperature dependence on predicted response. As with the investigation of geologic structure, noticeable differences in predicted temperatures (up to 29{degrees}C) were found to result.
This is a second annual report since the University Center of Excellence for Photovoltaics Research and Education was established at Georgia Tech. The major focus of the center is crystalline silicon, and the mission of the Center is to improve the fundamental understanding of the science and technology of advanced photovoltaic devices and materials, to fabricate high-efficiency cells, and develop low-cost processes, to provide training and enrich the equational experience of students in this field, and to increase US competitiveness by providing guidelines to industry and DOE to achieve cost-effective and high-efficiency photovoltaic devices. This report outlines the work of the Center from July 1993--June 1994.
A five watt pseudo chip in the middle of a SEM-X circuit card was tested with various heat conduction paths in a satellite type electronic box while mounted in a vacuum chamber. Previous tests showed low temperature differentials with the use of circuit board clamps. Flight hardware with thin box walls, low mass module frames, and thin heat covers were tested to determine the temperature differential at 5.0 watts as well as at lower powers. The smallest temperature differential was 23 degrees Celsius between the 5 watt pseudo chip and the cold plate.
This report summarizes the environmental surveillance activities conducted by Sandia National Laboratories, the US Environmental Protection Agency, and Kirk-Mayer, Inc., for the Tonopah Test Range operated by Sandia National Laboratories. Sandia National Laboratories` responsibility for environmental surveillance results extends to those activities performed by Sandia National Laboratories or under its direction. Results from other environmental surveillance activities are included to provide a measure of completeness in reporting. Other environmental compliance programs such as the National Environmental Policy Act of 1969, environmental permits, and environmental restoration and waste management programs are also included in this report, prepared for the US Department of Energy (DOE) in compliance with DOE Order 5400. 1.
A popular three-dimensional mesh generation scheme is to start with a quadrilateral of the surface of a volume, and then attempt to fill the interior of volume with hexahedra, so that the hexahedra touch the surface in exactly the given quadrilaterals. Folklore has maintained that there are many quadrilateral meshes for which no such compatible hexahedral mesh exists. In this paper we give an existence proof which contradicts this folklore: A quadrilateral mesh need only satisfy some very weak conditions for there to exist a compatible hexahedral mesh. For a volume that is topologically a ball, any quadrilateral mesh composed of an even number of quadrilaterals admits a compatible hexahedral mesh. We extend this to volumes of higher genus: There is a construction to reduce to the ball case if and only if certain cycles of edges are even.
This paper describes a product realization process developed and demonstrated at Sandia by the A-PRIMED (Agile Product Realization for Innovative Electro MEchanical Devices) project that integrates many of the key components of ``agile manufacturing`` into a complete, design-to-production process. Evidence indicates that the process has reduced the product realization cycle and assured product quality. Products included discriminators for a robotic quick change adapter and for an electronic defense system. These discriminators, built using A-PRIMED, met random vibration requirements and had life cycles that far surpass the performance obtained from earlier efforts.
Encryption performance, in terms of bits per second encrypted, has not scaled well as network performance has increased. The authors felt that multiple encryption modules operating in parallel would be the cornerstone of scalable encryption. One major problem with parallelizing encryption is ensuring that each encryption module is getting the proper portion of the key sequence at the correct point in the encryption or decryption of the message. Many encryption schemes use linear recurring sequences, which may be generated by a linear feedback shift register. Instead of using a linear feedback shift register, the authors describe a method to generate the linear recurring sequence by using parallel decimated sequences, one per encryption module. Computing decimated sequences can be time consuming, so the authors have also described a way to compute these sequences with logic gates rather than arithmetic operations.
A-PRIMED (Agile Product Realization for Innovative Electro MEchanical Devices) demonstrated new product development in24 days accompanied by improved product quality, through ability enabling technologies. A concurrent engineering communications infrastructure was developed that provided electronic data communications, information access, enterprise integration of computers and applications, and collaborative work tools. This paper describes how A-PRIMED did it through attention to technologies, processes, and people.
Laboratory-scale heater experiments are Proposed to observe thermohydrologic Processes in tuffaceous rock using existing equipment and x-ray imaging techniques. The purpose of the experiments is to gain understanding of the near-field behavior and thermodynamic environment surrounding a heat source. As a prelude to these experiments, numerical simulations are performed to determine design-related parameters such as optimal heating power and heating duration. In addition, the simulations aid in identifying and understanding thermal processes and mechanisms that may occur under a variety of experimental conditions. Results of the simulations show that convection may play an important role in the heat transfer and thermodynamic environment of the heater if the Rayleigh-Darcy number exceeds a critical value (= 10 for the laboratory experiments) depending on the type of backfill material within the annulus (or drift).
This report contains the guidance Functional Requirements for an Integrated Intrusion Detection and Access Control Annunciator System, and survey results of selected commercial systems. The survey questions were based upon the functional requirements; therefore, the results reflect which and sometimes how the guidance recommendations were met.
A combined laboratory and field investigation was carried out to determine the extent of coring-induced damage done to samples cored from Marker Bed 139 at the WIPP site. Coring-induced damage, if present, has the potential to significantly change the properties of the material used for laboratory testing relative to the in situ material properties, resulting in misleading conclusions. In particular, connected, crack-like damage could make the permeability of cored samples orders of magnitude greater than the in situ permeabilities. Our approach compared in situ velocity and resistivity measurements with laboratory measurements of the same properties. Differences between in situ and laboratory results could be attributed to differences in the porosity due to cracks. The question of the origin of the changes could not be answered directly from the results of the measurements. Pre-existing cracks, held closed by the in situ stress, could open when the core was cut free, or new cracks could be generated by coring-induced damage. We used core from closely spaced boreholes at three orientations (0{degree}, {plus_minus}45{degrees} relative to vertical) to address the origin of cracks. The absolute orientation of pre-existing cracks would be constant, independent of the borehole orientation. In contrast, cracks induced by coring were expected to show an orientation dependent on that of the source borehole.
The Department of Energy (DOE) has shutdown many production reactors; the Department has begun a major effort to also shutdown a wide variety of other nuclear facilities. Because so many facilities are being closed, it is necessary to place many of them into a safe- storage status, i.e., deactivation, before conducting decommissioning- for perhaps as long as 20 years. The challenge is to achieve this safe-storage condition in a cost-effective manner while remaining in compliance with applicable regulations. The DOE Office of Environmental Management, Office of Transition and Management, commissioned a lessons-learned study of commercial experience with safe storage and decommissioning. Although the majority of the commercial experience has been with reactors, many of the lessons learned presented in this document can provide insight into transitioning challenges that Will be faced by the DOE weapons complex.
The solubility of Th(IV) hydrous oxide was studied in concentrated 4m and 6m NaCl solutions as well as in MgCl[sub 2] solutions ranging in concentration from 1m to 3m over a broad range of hydrogen ion concentrations. The observed solubilities in all solutions showed the same trend as observed previously of higher solubilities at early equilibration times, usually 7 to 8 days, followed by decreases in solubility with time as the precipitates aged. The trend of decreasing solubility with time was more pronounced in NaCl solutions than in MgCl[sub 2] solutions. The observed ThO[sub 2](am) solubilities in concentrated NaCl solutions (i.e., 4m and 6m) were lower than previously reported solubilities in more dilute NaCl solutions (i.e., < 3M NaCl). The results in MgCl[sub 2] were similar in all solutions regardless of the MgCl[sub 2] concentration. Current thermodynamic models for the solubility of hydrous thorium, oxide in chloride solutions, which primarily describe only aqueous Th[sup 4+]-Cl[sup -] ion-interactions, predicted higher solubilities than observed in 4 and 6m NaCl as well as in all MgCl[sub 2] solutions. An improved aqueous thermodynamic model, which includes ion-interaction parameters for like charged species, is proposed to explain these results.
In the sol-gel processing of ceramic thin films it has been frequently noted that the processing behavior, microstructure and properties of the films are dependent on the nature of the coating solution. In an attempt to understand such processing-property relationships, we have systematically investigated the effects of precursor nature on thin film densification and crystallization for ZrO2 and TiO2 thin films. Metal alkoxide starting compounds, e.g., zirconium (IV) n-butoxide n-butanol and titanium (IV) i-propoxide, were reacted with acetic acid and 2,4-pentanedione to prepare coating solutions for thin film deposition. The use of these ligands resulted in solution oligomeric species of different nature. Studies of thin film processing indicated that film processing characteristics, i.e., consolidation, densification and crystallization, were strongly dependent on solution precursor nature. Ligand steric size, pyrolysis behavior, extent of modification, and precursor reactivity were found to be key variables in controlling film processing.
This paper theoretically compares the performance of simulated annealing and evolutionary algorithms. Our main result is that under mild conditions a wide variety of evolutionary algorithms can be shown to have greater performance than simulated annealing after a sufficiently large number of function evaluations. This class of EAs includes variants of evolutionary strategie and evolutionary programming, the canonical genetic algorithm, as well as a variety of genetic algorithms that have been applied to combinatorial optimization problems. The proof of this result is based on a performance analysis of a very general class of stochastic optimization algorithms, which has implications for the performance of a variety of other optimization algorithm.
This paper describes an application where transportation logistics and simulation tools are integrated to create a modeling environment for transportation planning. The Transportation Planning Model (TPM) is a tool developed for the Department of Energy (DOE) to aid in the long-term planning of their transportation resources. The focus of the tool is to aid DOE and Sandia National Laboratory analysts in the planning of future fleet sizes, driver and support personnel sizes, base site locations, and resource balancing among the base sites. The design approach is to develop a rapid modeling environment which integrates graphical user interfaces, logistics optimizing tools, and simulation modeling. Using the TPM an analyst can easily set up a shipment scenario and perform multiple ``What If`` evaluations. The TPM has been developed on personal computers using commercial off-the-shelf software tools under the WINDOW{reg_sign} operating environment.
Field emission flat panel displays place new demands on the performance of cathodoluminescent phosphors. In particular, such phosphors must be efficient at lower voltages (ca. 100-1000 V), and must withstand higher current densities than are present on cathode ray tube screens. ZnO:Zn has been studied extensively as a low-voltage phosphor, but problems such as poor chromatic saturation and temperature sensitivity of emission remain. In this work the use of terbium-doped garnet phases such as yttrium aluminum garnet (YAG) and gadolinium gallium garnet (GGG) as low voltage green-emitting phosphors is evaluated. Hydrothermal synthesis yields well-faceted YAG grains with particle diameters of less than 1 {mu}m. Cathodoluminescent efficiency at a particular voltage was not affected by synthetic route, though the hydrothermally synthesized material was less susceptible to damage at high power densities. An efficiency of 3.5 lm/W was observed for GGG:Tb at 800 V. Deposition of the phosphors onto conducting screens increased their efficiencies at very low voltages (< 200 V). These materials may be considered alternatives to reduced zinc oxide as green-emitting phosphors.
The potential exists in a nuclear reactor core melt severe accident for molten core debris to be dispersed under high pressure into the containment building. If this occurs, the set of phenomena that result in the transfer of energy to the containment atmosphere and its surroundings is referred to as direct containment heating (DCH). Because of the potential for DCH to lead to early containment failure, the U.S. Nuclear Regulatory Commission (USNRC) has sponsored an extensive research program consisting of experimental, analytical, and risk integration components. An important element of the analytical research has been the development and assessment of direct containment heating models in the CONTAIN code. This report documents the DCH models in the CONTAIN code. DCH models in CONTAIN for representing debris transport, trapping, chemical reactions, and heat transfer from debris to the containment atmosphere and surroundings are described. The descriptions include the governing equations and input instructions in CONTAIN unique to performing DCH calculations. Modifications made to the combustion models in CONTAIN for representing the combustion of DCH-produced and pre-existing hydrogen under DCH conditions are also described. Input table options for representing the discharge of debris from the RPV and the entrainment phase of the DCH process are also described. A sample calculation is presented to demonstrate the functionality of the models. The results show that reasonable behavior is obtained when the models are used to predict the sixth Zion geometry integral effects test at 1/10th scale.
Researchers contend that composite repairs (or structural reinforcement doublers) offer numerous advantages over metallic patches including corrosion resistance, light weight, high strength, elimination of rivets, and time savings in installation. Their use in commercial aviation has been stifled by uncertainties surrounding their application, subsequent inspection and long-term endurance. The process of repairing or reinforcing airplane structures is time consuming and the design is dependent upon an accompanying stress and fatigue analysis. A repair that is too stiff may result in a loss of fatigue life, continued growth of the crack being repaired, and the initiation of a new flaw in the undesirable high stress field around the patch. Uncertainties in load spectrums used to design repairs exacerbates these problems as does the use of rivets to apply conventional doublers. Many of these repair or structural reinforcement difficulties can be addressed through the use of composite doublers. Primary among unknown entities are the effects of non-optimum installations and the certification of adequate inspection procedures. This paper presents on overview of a program intended to introduce composite doubler technology to the US commercial aircraft fleet. In this project, a specific composite application has been chosen on an L-1011 aircraft in order to focus the tasks on application and operation issues. Through the use of laboratory test structures and flight demonstrations on an in-service L-1011 airplane, this study is investigating composite doubler design, fabrication, installation, structural integrity, and non-destructive evaluation. In addition to providing an overview of the L-1011 project, this paper focuses on a series of fatigue and strength tests which have been conducted in order to study the damage tolerance of composite doublers. Test results to-date are presented.
Vinyl-bridged polysilsesquioxane gels were formed through the use of sol-gel polymerization methods. Acid- and base-catalyzed samples were prepared from both the pure cis-(l) and pure trans-(2) isomers of 1, 2-bis(triethoxysilyl)ethylene. Gelation times of the two isomers were compared. The trans monomer 2 formed gels within a week while the cis monomer I failed to gel-even after several months. Gelation of 1 could be promoted by the addition of a coordinating metal such as palladium. The resulting cis- and trans- vinyl-bridged polysilsesquioxane gels were then processed either by vacuum drying to afford xerogels or by extracting with supercritical carbon dioxide to afford aerogels. These vinylbridged polysilsesquioxanes were characterized by SEM, nitrogen sorption porosimetry, solid State {sub 29}Si and {sub 13}C NMR and x-ray powder diffraction.
This document contains six reports on actinide chemistry research supporting the Waste Isolation Pilot Plant (WIPP). These reports, completed in FY94, are relevant to the estimation of the potential dissolved actinide concentrations in WIPP brines under repository breach scenarios. Estimates of potential dissolved actinide concentrations are necessary for WIPP performance assessment calculations. The specific topics covered within this document are: the complexation of oxalate with Th(IV) and U(VI); the stability of Pu(VI) in one WIPP-specific brine environment both with and without carbonate present; the solubility of Nd(III) in a WIPP Salado brine surrogate as a function of hydrogen ion concentration; the steady-state dissolved plutonium concentrations in a synthetic WIPP Culebra brine surrogate; the development of a model for Nd(III) solubility and speciation in dilute to concentrated sodium carbonate and sodium bicarbonate solutions; and the development of a model for Np(V) solubility and speciation in dilute to concentrated sodium Perchlorate, sodium carbonate, and sodium chloride media.
Salado Mass Concrete (SMC) has been developed for use as a seal component in the Waste Isolation Pilot Plant. This concrete is intended to be mixed from pre-bagged materials, have an initial slump of 10 in., and remain pumpable and placeable for two hours after mixing. It is a mass concrete because it will be placed in monoliths large enough that the heat generated during cement hydration has the potential to cause thermal expansion and subsequent cracking, a phenomenon to avoid in the seal system. This report describes effects on concrete properties of changes in ratio of water to cement, batch size, and variations in characteristics of different lots of individual components of the concrete. The research demonstrates that the concrete can be prepared from laboratory-batched or pre-bagged dry materials in batches from 1.5 ft{sup 3} to 5.0 yd{sup 3}, with no chemical admixtures other than the sodium chloride added to improve bonding with the host rock, at a water-to-cement ratio ranging from 0.36 to 0.42. All batches prepared according to established procedures had adequate workability for at least 1.5 hours, and achieved or exceeded the target compressive strength of 4500 psi at 180 days after casting. Portland cement and fly ash from different lots or sources did not have a measurable effect on concrete properties, but variations in a shrinkage-compensating cement used as a component of the concrete did appear to affect workability. A low initial temperature and the water-reducing and set-retarding functions of the salt are critical to meeting target properties.
Thermally activated batteries use an epoxy for encapsulation of the electrical feedthroughs in the header of the battery. When the thermal battery is thermally abused, the encapsulant can pyrolyze and generate large internal pressures. This causes the battery to vent in extreme cases. The nature of these gases has never been adequately documented. Therefore, a study was undertaken to address this deficiency. The pyrolysis of various encapsulants that have been used, or are being considered for use, in thermally activated batteries was studied over a temperature range of 155 to 455 C. The composition of the pyrolysis decomposition products was determined by gas chromatography/mass spectrometry (GS/MS). This determination is helpful in assessing the potential environmental and health effect for personnel exposed to such gases. In addition, the thermal stability of the various epoxies was measured by thermogravimetric analysis (TGA).
This report presents the results of 11 rotary shear tests conducted on replicas of three hollow cylinders of natural fractures with JRC values of 7.7, 9.4 and 12.0. The JRC values were determined from the results of laser profilometer measurements. The replicas were created from gypsum cement. By varying the water-to-gypsum cement ratio from 30 to 45%, fracture replicas with different values of compressive strength (JCS) were created. The rotary shear experiments were performed under constant normal (nominal) stresses ranging between 0.2 and 1.6 MPa. In this report, the shear test results are compared with predictions using Barton`s empirical peak shear strength equation. observations during the experiments indicate that only certain parts of the fracture profiles influence fracture shear strength and dilatancy. Under relatively low applied normal stresses, the JCS does not seem to have a significant effect on shear behavior. As an alternative, a new procedure for predicting the shear behavior of fractures was developed. The approach is based on basic fracture properties such as fracture surface profile data and the compressive strength, modulus of elasticity, and Poisson`s ratio of the fracture walls. Comparison between predictions and actual shear test results shows that the alternative procedure is a reliable method.
Sandia National Laboratories has established a Cooperative Research and Development Agreement with consortium members of the National Center for Manufacturing Sciences (NCMS) to develop fundamental generic technology in printed wiring board materials and surface finishes. We are investigating the effects of surface roughness on the wettability and solderability behavior of several types of copper board finishes to gain insight into surface morphologies that lead to improved solderability. In this paper, we present optical interterometry and scanning electron microscopy results for a variety of chemically-etched copper substrates. Initial testing on six chemical etches demonstrate that surface roughness can be greatly enhanced through chemical etching. Noticeable movements in solder wettability were observed to company increases in roughness.
Recent trends towards finer pitch devices and assembly with lead free solders have resulted in increased interest in NiPd plated component leads by the electronics industry. This paper discusses the performance of NiPd fine pitch components as determined by wettability, assembly performance and solder joint reliability. Assembly evaluations were performed with a lead free solder as well as with eutectic SnPb solder. The compatibility of the NiPd component leads with different circuit board finishes (metallic and organic azole) will also be discussed.
A consortium of United States utility concerns led by the Southern California Edison Company (SCE) is conducting a cooperative project with the US Department of Energy (DOE), Sandia National Laboratories, and industry to convert the 10-MW Solar One Power Tower Pilot Plant to molten nitrate salt technology. The conversion involves installation of a new receiver, a new thermal storage system, and a new steam generator; it utilizes Solar One`s heliostat field and turbine generator. Successful operation of the converted plant, called Solar Two, will reduce economic risks in building initial commercial power tow projects and accelerate the commercial acceptance of this promising renewable energy technology. The estimated cost of Solar Two, including its three-year test period, is $48.5 million. The plant will begin operation in early 1996.
Plasma jet generators have been designed and tested which used an explosive driver and shocktube with a rectangular cross section that optimize the flow velocity and electrical conductivity. The latest in a series of designs has been tested using a reactive load to diagnose the electrical properties of the MHD generator/electromagnet combination. The results of these tests indicate that the plasma jet/MHD generator design does generate a flow velocity greater than 25 km/s and produces several gigawatts of pulsed power in a very small package size. A larger, new generator design is also presented.
A simple and intuitive formalism is presented to describe diffraction in multi-layered periodic structures. We use the well known results from scalar analysis (wave propagation in homogeneous layered media) and show that they can be generalized rather readily to vector problems such as diffraction analysis. Specifically, we derive: (1) generalized Fresnel equations appropriate for reflection and transmission from an infinitely thick grating, (2) a generalized Airy formula for thin-film to describe reflection and transmission of light through a lamellar grating and (3) a matrix propagation method akin to that used for multi-layer thin film analysis. The results developed here complement the recent work on R-matrix and S-matrix propagation algorithms that have been used in connection with modal and differential grating theories. These algorithms have proven to be numerically stable for calculating diffraction efficiencies from deep groove gratings. The formalism developed here expands upon the earlier literature by providing important details that are hitherto unavailable.
Batch-fabricated silicon seismic transducers could revolutionize the discipline of CTBT monitoring by providing inexpensive, easily depolyable sensor arrays. Although our goal is to fabricate seismic sensors that provide the same performance level as the current state-of-the-art ``macro`` systems, if necessary one could deploy a larger number of these small sensors at closer proximity to the location being monitored in order to compensate for lower performance. We have chosen a modified pendulum design and are manufacturing prototypes in two different silicon micromachining fabrication technologies. The first set of prototypes, fabricated in our advanced surface- micromachining technology, are currently being packaged for testing in servo circuits -- we anticipate that these devices, which have masses in the 1--10 {mu}g range, will resolve sub-mG signals. Concurrently, we are developing a novel ``mold`` micromachining technology that promises to make proof masses in the 1--10 mg range possible -- our calculations indicate that devices made in this new technology will resolve down to at least sub-{mu}G signals, and may even approach to 10{sup {minus}10} G/{radical}Hz acceleration levels found in the low-earth-noise model.
Fluorescent microthermal imaging (FMI) involves coating a sample surface with a thin inorganic-based film that, upon exposure to uv light, emits temperature-dependent fluorescence. FMI offers the ability to create thermal maps of integrated circuits with a thermal resolution theoretically limited to 1 m{degree}C and a spatial resolution diffraction-limited to 0.3 {mu}m. Even though FMI has been in use for more than a decade, many factors that can affect the thermal image quality have not been studied well. This paper presents recent results showing the limitations from photon shot noise and the improvement in signal-to-noise ratio from signal averaging. Three important factors in film preparation and characterization are presented that have a significant impact on thermal quality and sensitivity of FMI: uv bleaching, film dilution, and film curing. It is shown how proper film preparation and data collection method can dramatically improve the quality of FMI thermal images.
Computational simulations of the impacts of comet Shoemaker-Levy 9 (SL9) fragments on Jupiter have provided a framework for interpreting the observations. A reasonably consistent picture has emerged, along with a more detailed understanding of atmospheric collisional processes. Several aspects of Earth-impact hazards can be re-evaluated with knowledge gained from observations and from simulations of SL9. In particular, the threat of impact-generated plumes to satellites in low-Earth orbit (LEO) should be recognized. Preliminary 2-D computational simulations suggest that impacts of a size that recur about once per century generate plumes that rise to nearly 1000 kilometers over an area thousands of kilometers in diameter. Detailed modeling of such plumes should be carried out to quantify this threat to satellites in the near-Earth environment. Careful observations of high-energy atmospheric entry events should be made using both satellite and ground-based instruments to provide validation for these computational models.
This contribution describes a proposed information element that can convey authentication information within an ATM signaling message. The design of this information element provides a large amount of flexibility to the user because it does not specify a particular signature algorithm, and it does not specify which information elements must accompany the Authentication IE in a signaling message. This allows the user to implement authenticated signaling based on her site`s security policies and performance requirements.
Both n- and p-type doping have been achieved in GaN using Si{sup +} or Mg{sup +}/P{sup +} implantation, respectively, followed annealing at {ge} 1050{degrees}C. Using proximity rapid thermal annealing (10sec) the GaN surface retains both smooth morphology and its original stoichiometry. Variable temperature Hall measurements reveal approximate energy levels of 62meV for the implanted Si and 171meV for the Mg, which are similar to their values in epitaxially grown GaN. Implant isolation of both n- and p-type GaN, and n-type In{sub 0.75}Al{sub 0.25}N with multiple energy inert species (e.g. N{sup +} or F{sup +}) produces high resistivity ({ge}10{sup 8}{omega}/{open_square}) after subsequent annealing in the range 600-700{degrees}C. Smaller increases in sheet resistance are observed for In{sub x}Ga{sup 1-x}N (x=0.33-0.75) under the same conditions due to the smaller energy bandgaps and the shallower energy levels of the damage-related states controlling the resistivity.
A life prediction model is being developed by the authors for application to metal matrix composites (MMC`s). The systems under study are continuous silicon carbide fibers imbedded in titanium matrix. The model utilizes a computationally based framework based on thermodynamics and continuum mechanics, and accounts for matrix inelasticity, damage evolution, and environmental degradation due to oxidation. The computational model utilizes the finite element method, and an evolutionary analysis of a unit cell is accomplished via a time stepping algorithm. The computational scheme accounts for damage growth such as fiber-matrix debonding, surface cracking, and matrix cracking via the inclusion of cohesive zone elements in the unit cell. These elements are located based on experimental evidence also obtained by the authors. The current paper outlines the formulation utilized by the authors to solve this problem, and recent results are discussed. Specifically, results are given for a four-ply unidirectional composite subjected to cyclic fatigue loading at 650{degrees}C both in air and inert gas. The effects of oxidation on the life of the composite are predicted with the model, and the results are compared to limited experimental results.
This paper describes the use of {open_quotes}Formula 456{close_quotes} an aliphatic amine cured epoxy for impregnating coils. Methylene dianiline (MDA) has been used for more than 20 years as the curing agent for various epoxy formulations throughout the Department of Energy. Sandia National Laboratories began the process of replacing MDA with other formulations because of regulations imposed by OSHA on the use of MDA.
Optical diagnostics are extremely useful in fluid mechanics because they generally have high inherent bandwidth, and are non-intrusive. However, since optical probe measurements inherently integrate all information along the optical path, it is often difficult to isolate out-of-plane components in 3-dimensional flow events. It is also hard to make independent measurements of internal flow structure. Using an arrangement of one-dimensional wavefront sensors, we have developed a system that uses tomographic reconstruction to make two-dimensional measurements in an arbitrary flow. These measurements provide complete information in a plane normal to the flow. We have applied this system to the subsonic free jet because of the wide range of flow scales available. These measurements rely on the development of a series of one-dimensional wavefront sensors that are used to measure line-integral density variations in the flow of interest. These sensors have been constructed using linear CCD cameras and binary optics lenslet arrays. In designing these arrays, we have considered the coherent coupling between adjacent lenses and have made comparisons between theory and experimental noise measurements. The paper will present examples of the wavefront sensor development, line-integral measurements as a function of various experimental parameters, and sample tomographic reconstructions.
Adaptive finite element analysis demands a great deal of computational resources, and as such is most appropriately solved in a massively parallel computer environment. This analysis will require other parallel algorithms before it can fully utilize MP computers, one of which is parallel adaptive meshing. A version of the paving algorithm is being designed which operates in parallel but which also retains the robustness and other desirable features present in the serial algorithm. Adaptive paving in a production mode is demonstrated using a Babuska-Rheinboldt error estimator on a classic linearly elastic plate problem. The design of the parallel paving algorithm is described, and is based on the decomposition of a surface into {open_quotes}virtual{close_quotes} surfaces. The topology of the virtual surface boundaries is defined using mesh entities (mesh nodes and edges) so as to allow movement of these boundaries with smoothing and other operations. This arrangement allows the use of the standard paving algorithm on subdomain interiors, after the negotiation of the boundary mesh.
An overview of the major sensor and actuator projects using the micromachining capabilities of the Microelectronics Development Laboratory at Sandia National Laboratories are presented. Development efforts are underway for a variety of micromechanical devices and control electronics for those devices. Our efforts are concentrated in the area of surface micromachining. Pressure sensors based on silicon nitride diaphragms and hot polysilicon filaments for calorimetric gas sensing have been developed. Accelerometers based upon high-aspect ratio surface micromachining are being developed. Actuation mechanisms employing either electrostatic or steam power are being combined with a three-level active (plus an additional passive level) polysilicon surface micromachining process to couple these actuators to external devices. The results of efforts toward integration of micromechanics with the driving electronics for actuators or the amplification/signal processing electronics for sensors is also described. This effort includes a CMOS-first, tungsten metallization process to allow the CMOS electronics to withstand high-temperature micromechanical processing. Also, a unique micromechanics-first approach is being pursued in which the micromechanical devices are embedded below the surface of the starting material for the CMOS.
An End-To-End Simulation capability for software development and validation of missile flight software on the actual embedded computer has been developed utilizing a 486 PC, i860 DSP coprocessor, embedded flight computer and custom dual port memory interface hardware. This system allows real-time interrupt driven embedded flight software development and checkout. The flight software runs in a Sandia Digital Airborne Computer (SANDAC) and reads and writes actual hardware sensor locations in which IMU (Inertial Measurements Unit) data resides. The simulator provides six degree of freedom real-time dynamic simulation, accurate real-time discrete sensor data and acts on commands and discretes from the flight computer. This system was utilized in the development and validation of the successful premier flight of the Digital Miniature Attitude Reference System (DMARS) in January 1995 at the White Sands Missile Range on a two stage attitude controlled sounding rocket.
Millimeter wave resonant measurements are commonly used for surface and near-surface materials characterization including the detection of cracks and defects, analysis of semiconducting and dielectric materials, and analysis of metallic electrical properties beneath coatings. Recent work has also shown the approach to be useful in evaluating corrosion products and the detection of incipient corrosion and corrosion cracking. In the analysis area, complex permittivity data of the corrosion products can be extracted, usually with accuracy of a few percent or better, to aid in identification of the product and possibly of mechanisms. In the detection area, corrosion-related cracks of order 100{mu}m or less near the surface have been detected and corrosion products have been detected beneath a variety of paints. Surface preparation requirements are minimal, particularly compared to some optical techniques, giving increased hope of field applicability. A number of examples of NDI on aircraft related materials and structures will be presented along with an assessment of detection and accuracy limits.
A nonequilibrium continuum mixture model has been incorporated into the CTH shock physics code to describe deflagration-to-detonation transition in granular energetic materials. This approach treats multiple thermodynamic and mechanics fields including the effects of relative material motion, rate-dependent compaction and interphase exchange of mass, momentum and energy. A finite volume description is formulated and internal state variables are solved using an operator-splitting method. Numerical simulations of low-velocity impact on a weakly-confined porous propellant bed are presented which display lateral wall release leading to curved compaction and reaction wave behavior.
The purpose of this discussion is to introduce the session on the Progress on the Resolution of Severe Accident Issues. There has been much work in the area of resolution of severe accident issues over the past few years. This work has been focused on those issues most important to risk as assessed by comprehensive studies such as NUREG-1150. In particular, issues associated with early containment failure have been analyzed. These efforts to resolve issues have been hampered by the fact that {open_quotes}issue resolution{close_quotes} has not always been well defined. The term {open_quotes}issue resolution{close_quotes} conjures tip different images for the regulator, the accident analyst, the physicist, and the probabalist. In fact it is common to have as many different images of issue resolution as there are people in the room. This issue is complicated by the fact that the uncertainty in severe accident issues is enormous. (When convolved, the quantitative uncertainty in an integrated analysis due to severe accident issues can span several orders of magnitude.) In this summary, hierarchy is presented in an attempt to add some perspective to the resolution of issues in the face of large uncertainties. Recommendations are also made for analysts communicating in the area of issue resolution.
It is well-known that dry pressing of ceramic powders leads to density gradients in a ceramic compact resulting in non-uniform shrinkage during densification. This necessitates diamond grinding to final dimensions which, in addition to being an extra processing step, greatly increases the manufacturing cost of ceramic components. To develop methods to control and thus mitigate density variations in compacted powders, it has been an objective of researchers to better understand the mechanics of the compaction process and the underlying material and tooling effects on the formation of density gradients. This paper presents a review of models existing in the literature related to the compaction behavior of ceramic powders. In particular, this paper focuses on several well-known compaction models that predict pressure and density variations in powder compacts.
Models used in performance assessment and site characterization activities related to nuclear waste disposal rely on simplified representations of solute/rock interactions, hydrologic flow field and the material properties of the rock layers surrounding the repository. A crucial element in the design of these models is the validity of these simplifying assumptions. An intermediate-scale experiment is being carried out at the Experimental Engineered Test Facility at Los Alamos Laboratory by the Los Alamos and Sandia National Laboratories to develop a strategy to validate key geochemical and hydrological assumptions in performance assessment models used by the Yucca Mountain Site Characterization Project.
DOE contracted with Sandia to install a radar acquisition system (RAMS) to gather aircraft flight data near the Pantex Plant in Amarillo, TX. To support this effort, data reduction tools were needed to help analyze the radar data. Plot-flight is one of several data reduction tools that comprise the Sandia Airspace Recording System (SARS). The radar data is needed to support the Pantex Environmental Impact Study. Plot-flight is a DOS-based plot program that allows analysts to replay pre-recorded air traffic over Albuquerque and Amarillo. The program is flexible enough to permit replay of daily flights either sequentially, by range, or by Beacon ID. In addition to replay, the program is setup for data entry. Analysts can correlate electronic aircraft flight data to the green strip flights logs obtained from the local air traffic control center. The green strips are used by air traffic controllers to record each scheduled flight. The green strips have information not available electronically such as aircraft type and aircraft ID. This type of information is necessary to accommodate the current models used in aircraft crash analysis. Plot-flight correlates the hand-written information from the green strips to the recorded aircraft flight.
The authors have performed experiments to study the effect of thermal degradation on shock sensitivity and growth to detonation of several high-density plastic bonded explosives, confined in stainless steel cells. Assemblies were heated in situ in the target chamber of a light-gas gun. Confinement was varied to allow, in some cases, for thermal expansion of the explosive, and in other cases to vent the decomposition gases. Particle velocity profiles were measured using VISAR at a LiF window interface. Results for the IHE PBX-9502 showed that its sensitivity to shock initiation could be dramatically increased or decreased depending on the confinement conditions during heating. Effects were much less pronounced for PBX-9404 and PBX-9501.
In the post-Cold War climate of reduced budgets at the national laboratories, the Sites Planning Department at Sandia National Laboratories was faced with the problem of securing funding for capital construction projects in a very competitive environment. The Department of Energy (DOE), felt that requests for new facilities were not always well coordinated with its mission needs. The Sites Planning Department needed to revolutionize the way they were doing business. To be successful in obtaining approval and funding for future facilities, they recognized the need to concentrate their efforts on project proposals that tap strategic programs at DOE. The authors developed a series of new processes to identify, evaluate, prioritize, and develop line item project proposals to request approval and obtain funding. A matrixed group of sites and facilities directors was formed to establish criteria and make preliminary recommendations to upper management. Matrixed working groups were also established at the staff level to develop and prepare projects for the prioritization process. Ultimately, similar processes will be applied to all project types, and a prioritized plan generated for each. These plans will become the blueprint for an overarching strategic site plan. What started as a means of increasing success in obtaining approval and funding of capital projects has launched a whole new approach to project development that permits incorporation of facilities planning into overall corporate strategic planning.
The purpose of this program was to develop a calibration curve (stress as a function of change in gauge resistance/gauge resistance) and to obtain gauge repeatability data for Micro-Measurements stripped manganin thin-foiled gauges up to 6.1 GPa in ALOX (42% by volume alumina in Epon 828 epoxy) material. A light-gas gun was used to drive an ALOX impactor into the ALOX target containing four gauges in a centered diamond arrangement. Tilt and velocity of the impactor were measured along with the gauge outputs. Impact stresses from 0.5 to 6.1 GPa were selected in increments of 0.7 GPa with duplicate tests done at 0.5, 3.3 and 6.1 GPa. A total of twelve tests were conducted using ALOX. Three initial tests were done using polymethyl methacrylate (PMMA) as the impactor and target at an impact pressure of 3.0 GPa for comparison of gauge output with analysis and literature values. The installed gauge, stripped of its backing, has a nominal thickness of 5 {micro}m. The thin gauge and high speed instrumentation allowed higher time resolution measurements than can be obtained with manganin wire.
The application of computer simulation to grain growth and recrystallization was strongly stimulated in the early 80s by the realization that Monte Carlo models could be applied to problems of grain structure evolution. By extension of the Ising model for domain modeling of magnetic domains to the Potts model (with generalized spin numbers) it was then possible to represent discretely grains (domains) by regions of similarly oriented sets of material (lattice) points. In parallel with this fascinating development, there also occured notable work on analytical models, especially by Abbruzzese and Bunge, which has been particularly useful for understanding the variation of texture (crystallographic preferred orientation) during grain growth processes. Geometric models of recrystallization, worked on most recently and productively by Nes et al., have been useful in connection with grain size prediction as a result of recrystallization. Also, mesh-based models have been developed to a high degree by Kawasaki, Fradkov and others, and, rather recently, by Humphreys to model not just grain growth but also the nucleation process in recrystallization. These models have the strength that they deal with the essential features of grains, i.e. the nodes, but have some limitations when second phases must be considered. These various approaches to modeling of recrystallization processes will be reviewed, with a special emphasis on practical approaches to implementing the Potts model. This model has been remarkably successful in modeling such diverse phenomena as dynamic recrystallization, secondary recrystallization (abnormal grain growth), particle-inhibited recrystallization, and grain structure evolution in soldering and welding. In summary, the application of mesoscopic simulation to the phenomenon of recrystallization has yielded much new insight into some longstanding deficiencies in our understanding.
Plasma etching and desmear processes for printed wiring board (PWB) manufacture are difficult to predict and control. Non-uniformity of most plasma processes and sensitivity to environmental changes make it difficult to maintain process stability from day to day. To assure plasma process performance, weight loss coupons or post-plasma destructive testing must be used. These techniques are not real-time methods however, and do not allow for immediate diagnosis and process correction. These tests often require scrapping some fraction of a batch to insure the integrity of the rest. Since these tests verify a successful cycle with post-plasma diagnostics, poor test results often determine that a batch is substandard and the resulting parts unusable. These tests are a costly part of the overall fabrication cost. A more efficient method of testing would allow for constant monitoring of plasma conditions and process control. Process anomalies should be detected and corrected before the parts being treated are damaged. Real time monitoring would allow for instantaneous corrections. Multiple site monitoring would allow for process mapping within one system or simultaneous monitoring of multiple systems. Optical emission spectroscopy conducted external to the plasma apparatus would allow for this sort of multifunctional analysis without perturbing the glow discharge. In this paper, optical emission spectroscopy for non-intrusive, in situ process control will be explored along with applications of this technique to for process control, failure analysis and endpoint determination in PWB manufacture.
Jupiter is a Sandia initiative to develop the next generation of fast Z-pinch drivers for applications to high energy density physics, inertial confinement fusion, and radiation effects simulation. Jupiter will also provide unique capabilities for science research in a broad spectrum of areas involving ultra high magnetic fields, hot/dense plasmas, x-ray physics, intense neutron sources, etc. The program is based on the premise that a single facility using magnetically driven implosions can meet the needs in these multiple program areas. Jupiter requires a 450-500 TW, 8-10 MV, {approx} 100 ns pulsed power generator to impart - 15 MJ kinetic energy to an imploding plasma load. The baseline concept uses a highly modular, robust architecture with demonstrated performance reliability. The design also has the flexibility to drive longer implosion times. This paper describes the Jupiter accelerator concept, and the research underway to establish the technological readiness to proceed with construction of the facility.
The thermal conductivities of a variety of insulating materials used in thermal batteries were measured in atmospheres of argon and helium using several techniques. (Helium was used to simulate the hydrogen atmosphere that results when a Li(Si)/FeS{sub 2} thermal battery ages.) The guarded-hot-plate method was used with the Min-K insulation because of its extremely low thermal conductivity. For comparison purposes, the thermal conductivity of the Min-K insulating board was also measured using the hot-probe method. The thermal-comparator method was used for the rigid Fiberfrax board and Fiberfrax paper. The thermal conductivity of the paper was measured under several levels of compression to simulate the conditions of the insulating wrap used on the stack in a thermal battery. The results of preliminary thermal-characterization tests with several silica aerogel materials are also presented.
Sandia National Laboratories has recently completed construction of a new Explosive Components Facility (ECF) that will be used for the research and development of advanced explosives technology. The ECF includes nine indoor firing pads for detonating explosives and monitoring the detonations. Department of Energy requirements for certification of this facility include detonation of explosive levels up to 125 percent of the rated firing pad capacity with no visual structural degradation resulting from the explosion. The Explosives Projects and Diagnostics Department at Sandia decided to expand this certification process to include vibration and acoustic monitoring at various locations throughout the building during these explosive events. This information could then be used to help determine the best locations for noise and vibration sensitive equipment (e.g. scanning electron microscopes) used for analysis throughout the building. This facility has many unique isolation features built into the explosive chamber and laboratory areas of the building that allow normal operation of other building activities during explosive tests. This paper discusses the design of this facility and the various types of explosive testing performed by the Explosives Projects and Diagnostics Department at Sandia. However, the primary focus of the paper is directed at the vibration and acoustic data acquired during the certification process. This includes the vibration test setup and data acquisition parameters, as well as analysis methods used for generating peak acceleration levels and spectral information. Concerns over instrumentation issues such as the choice of transducers (appropriate ranges, resonant frequencies, etc.) and measurements with long cable lengths (500 feet) are also discussed.
Mesoporous is defined as 20{le}d{le}500{angstrom}. Mesoporous materials with narrow pore size distributions may be useful as hosts, supports, catalysts, or separation media for small molecules. An ensemble of organic molecules to create a larger template has been used to synthesize ordered mesoporous materials. The silicon alkoxide precursors TEOS and TMOS were examined. Cosolvents were used to control pore size and the structure of the mesophase. Effects of anions (salts) on mesophase formation were examined. Properties of mesophases made from homogeneous solutions are discussed.
Supercritical carbon dioxide extraction is being explored as a waste minimization technique for separating oils, greases, and solvents from solid waste. The contaminants are dissolved into the supercritical fluid and precipitated out upon depressurization. The carbon dioxide solvent can then be recycled for continued use. Definitions of the temperature, pressure, flowrate, and potential co-solvents are required to establish the optimum conditions for hazardous contaminant removal. Excellent extractive capability for common manufacturing oils, greases, and solvents has been observed in both supercritical and liquid carbon dioxide.
This report provides calculational results from the updated Lagrangian structural finite-element programs SPECTROM-32 and SPECTROM-333 for the purpose of qualifying these codes to perform analyses of structural situations in the Waste Isolation Pilot Plant (WIPP). Results are presented for the Second WIPP Benchmark (Benchmark II) Problems and for a simplified heated room problem used in a parallel design calculation study. The Benchmark II problems consist of an isothermal room problem and a heated room problem. The stratigraphy involves 27 distinct geologic layers including ten clay seams of which four are modeled as frictionless sliding interfaces. The analyses of the Benchmark II problems consider a 10-year simulation period. The evaluation of nine structural codes used in the Benchmark II problems shows that inclusion of finite-strain effects is not as significant as observed for the simplified heated room problem, and a variety of finite-strain and small-strain formulations produced similar results. The simplified heated room problem provides stratigraphic complexity equivalent to the Benchmark II problems but neglects sliding along the clay seams. The simplified heated problem does, however, provide a calculational check case where the small strain-formulation produced room closures about 20 percent greater than those obtained using finite-strain formulations. A discussion is given of each of the solved problems, and the computational results are compared with available published results. In general, the results of the two SPECTROM large strain codes compare favorably with results from other codes used to solve the problems.
This paper argues that cooperative monitoring plays a critical role in the implementation of regional security agreements and confidence building measures. A framework for developing cooperative monitoring options is proposed and several possibilities for relating bilateral and regional monitoring systems to international monitoring systems are discussed. Three bilateral or regional agreements are analyzed briefly to illustrate different possibilities: (1) the demilitarization of the Sinai region between Israel and Egypt in the 1970s; (2) the 1991 quadripartite agreement for monitoring nuclear facilities among Brazil, Argentina, The Argentine-Brazilian Agency for Accounting and Control of Nuclear Materials and the International Atomic Energy Agency; and (3) a bilateral Open Skies agreement between Hungary and Romania in 1991. These examples illustrate that the relationship of regional or bilateral arms control or security agreements to international agreements depends on a number of factors: the overlap of provisions between regional and international agreements; the degree of interest in a regional agreement among the international community; efficiency in implementing the agreement; and numerous political considerations.Given the importance of regional security to the international community, regions should be encouraged to develop their own infrastructure for implementing regional arms control and other security agreements. A regional infrastructure need not preclude participation in an international regime. On the contrary, establishing regional institutions for arms control and nonproliferation could result in more proactive participation of regional parties in developing solutions for regional and international problems, thereby strengthening existing and future international regimes. Possible first steps for strengthening regional infrastructures are identified and potential technical requirements are discussed.
The Department of Energy Order 5500.3A requires facility-specific hazards assessments be prepared, maintained, and used for emergency planning purposes. This hazards assessment document describes the chemical and radiological hazards associated with the Glass Formulation and Fabrication Laboratory, Building 864. The entire inventory was screened according to the potential airborne impact to onsite and offsite individuals. The air dispersion model, ALOHA, estimated pollutant concentrations downwind from the source of a release, taking into consideration the toxicological and physical characteristics of the release site, the atmospheric conditions, and the circumstances of the release. The greatest distances at which a postulated facility event will produce consequences exceeding the ERPG-2 threshold is 96 meters. The highest emergency classification is a Site Area Emergency. The Emergency Planning Zone is 100 meters.
We describe a new concept for producing, on a single substrate, a two-dimensional array of optical interference filters where the pass-band of each element can be independently specified. The interference filter is formed by optically contacting two dielectric mirrors so that the top quarter-wave films of the two mirrors form a Fabry-Perot cavity having a half-wave thickness. In the new device, we propose to etch an array of sub-wavelength patterns into the top surface of one of the mirrors before forming the cavity. The patterns must have a pitch shorter than the operational wavelength in order to eliminate diffraction. By changing the index of refraction of the half-wave layer, or the optical thickness of the cavity, the patterning is used to shift the pass-band and form an array of interference filters. One approach to producing the array is to change the fill factor of the pattern. Once the filter array is produced it may be mated to a two-dimensional detector array to form a miniature spectrophotometer.
The Saturn accelerator at Sandia National Laboratories is a high power, variable-spectrum, x-ray source capable of simulating radiation effects of nuclear countermeasures on electronic and material components of space systems. It can also function as a pulsed-power and radiation source, and as a diagnostic test bed for a variety of applications. Obtaining highly accurate measurements of the emission spectra is difficult because the high intensity x-rays and MegaAmpere levels of current inside the experiment chamber can damage or destroy electronic measurement devices. For these reasons, an optical based measurement system has been designed, developed and successfully tested in the Saturn accelerator. The system uses fiber optic coupled sensor(s) connected to a specialized Doppler interferometer system which analyzes the shock wave imparted into a target material. This paper describes the optical system, its related components, and material response data of polymethyl methacrylate.
A computationally simple method for estimating gamma-ray skyshine dose rates has been developed on the basis of the line-beam response function. Both Monte Carlo and pointkernel calculations that account for both annihilation and bremsstrahlung were used in the generation of line beam response functions (LBRF) for gamma-ray energies between 10 and 100 MeV. The LBRF is approximated by a three-parameter formula. By combining results with those obtained in an earlier study for gamma energies below 10 MeV, LBRF values are readily and accurately evaluated for source energies between 0.02 and 100 MeV, for source-to-detector distances between 1 and 3000 m, and beam angles as great as 180 degrees. Tables of the parameters for the approximate LBRF are presented. The new response functions are then applied to three simple skyshine geometries, an open silo geometry, an infinite wall, and a rectangular four-wall building. Results are compared to those of previous calculations and to benchmark measurements. A new approach is introduced to account for overhead shielding of the skyshine source and compared to the simplistic exponential-attenuation method used in earlier studies. The effect of the air-ground interface, usually neglected in gamma skyshine studies, is also examined and an empirical correction factor is introduced. Finally, a revised code based on the improved LBRF approximations and the treatment of the overhead shielding is presented, and results shown for several benchmark problems.
A description of a three-level mechanical polysilicon surface-micromachining technology including a discussion of the advantages of this level of process complexity is presented. This technology is capable of forming mechanical elements ranging from simple cantilevered beams to complex, interconnected, interactive, microactuated micromechanisms. The inclusion of a third deposited layer of mechanical polysilicon greatly extends the degree of complexity available for micromechanism design. Additional features of the Sandia three-level process include the use of Chemical-Mechanical Polishing (CMP) for planarization, and the integration of micromechanics with the Sandia CMOS circuit process. The latter effort includes a CMOS-first, tungsten metallization process to allow the CMOS electronics to withstand high-temperature micromechanical processing. Alternatively, a novel micromechanics-first approach wherein the micromechanical devices are processed first in a well below the surface of the CMOS starting material followed by the standard, aluminum metallization CMOS process is also being pursued. Following the description of the polysilicon surface micromachining are examples of the major sensor and actuator projects based on this technology at the Microelectronics Development Laboratory (MDL) at Sandia National Laboratories. Efforts at the MDL are concentrated in the technology of surface micromachining due to the availability of and compatibility with standard CMOS processes. The primary sensors discussed are a silicon nitride membrane pressure sensor, hot polysilicon filaments for calorimetric gas sensing, and a smart hydrogen sensor. Examples of actuation mechanisms coupled to external devices are also presented. These actuators utilize the three-level process (plus an additional passive level) and employ either surface tension or electrostatic forces.
This report contains a comprehensive National Environmental Policy Act (NEPA) Compliance Guide for the Sandia National Laboratories. It is based on the Council on Environmental Quality (CEQ) NEPA regulations in 40 CFR Parts 1500 through 1508; the US Department of Energy (DOE) N-EPA implementing procedures in 10 CFR Part 102 1; DOE Order 5440.1E; the DOE ``Secretarial Policy Statement on the National Environmental Policy Act`` of June 1994- Sandia NEPA compliance procedures-, and other CEQ and DOE guidance. The Guide includes step-by-step procedures for preparation of Environmental Checklists/Action Descriptions Memoranda (ECL/ADMs), Environmental Assessments (EAs), and Environmental Impact Statements (EISs). It also includes sections on ``Dealing With NEPA Documentation Problems`` and ``Special N-EPA Compliance Issues.``
Structural dynamic testing is concerned with estimation of system properties, including frequency response functions and modal characteristics. These properties are derived from tests on the structure of interest, during which excitations and responses are measured and Fourier techniques are used to reduce the data. The inputs used in a test are frequently radom and excite random responses in the structure of interest. When these random inputs and responses are analyzed they yield estimates of system properties that are random variable and random process realizations. Of course, such estimates of system properties vary randomly from one test to another, but even when deterministic inputs are used to excite a structure, the estimated properties vary from test to test. When test excitations and responses are normally distributed, classical techniques permit us to statistically analyze inputs, responses, and system parameters. However, when the input excitations are non-normal, the system is nonlinear, and/or the property of interest is anything but the simplest, the classical analyses break down. The bootstrap is a technique for the statistical analysis of data that are not necessarily normally distributed. It can be used to statistically analyze any measure of input excitation on response, or any system property, when data are available to make an estimate. It is designed to estimate the standard error, bias, and confidence intervals of parameter estimates. This paper shows how the bootstrap can be applied to the statistical analysis of modal parameters.
An option for controlling contaminant migration from plumes and buried waste sites is to construct a subsurface barrier of a low-permeability material. The successful application of subsurface barriers requires processes to verify the emplacement and effectiveness of barrier and to monitor the performance of a barrier after emplacement. Non destructive and remote sensing techniques, such as geophysical methods, are possible technologies to address these needs. The changes in mechanical, hydrologic and chemical properties associated with the emplacement of an engineered barrier will affect geophysical properties such a seismic velocity, electrical conductivity, and dielectric constant. Also, the barrier, once emplaced and interacting with the in situ geologic system, may affect the paths along which electrical current flows in the subsurface. These changes in properties and processes facilitate the detection and monitoring of the barrier. The approaches to characterizing and monitoring engineered barriers can be divided between (1) methods that directly image the barrier using the contrasts in physical properties between the barrier and the host soil or rock and (2) methods that reflect flow processes around or through the barrier. For example, seismic methods that delineate the changes in density and stiffness associated with the barrier represents a direct imaging method. Electrical self potential methods and flow probes based on heat flow methods represent techniques that can delineate the flow path or flow processes around and through a barrier.
We have developed a working prototype of a grid-based global event detection system based on waveform correlation. The algorithm comes from a long-period detector but we have recast it in a full matrix formulation which can reduce the number of multiplications needed by better than two orders of magnitude for realistic monitoring scenarios. The reduction is made possible by eliminating redundant multiplications in the original formulation. All unique correlations for a given origin time are stored in a correlation matrix (C) which is formed by a full matrix product of a Master Image matrix (M) and a data matrix (D). The detector value at each grid point is calculated by following a different summation path through the correlation matrix. Master Images can be derived either empirically or synthetically. Our testing has used synthetic Master Images because their influence on the detector is easier to understand. We tested the system using the matrix formulation with continuous data from the IRIS (Incorporate Research Institutes for Seismology) broadband global network to monitor a 2 degree evenly spaced surface grid with a time discretization of 1 sps; we successfully detected the largest event in a two hour segment from October 1993. The output at the correct gridpoint was at least 33% larger than at adjacent grid points, and the output at the correct gridpoint at the correct origin time was more than 500% larger than the output at the same gridpoint immediately before or after. Analysis of the C matrix for the origin time of the event demonstrates that there are many significant ``false`` correlations of observed phases with incorrect predicted phases. These false correlations dull the sensitivity of the detector and so must be dealt with if our system is to attain detection thresholds consistent with a Comprehensive Test Ban Treaty (CTBT).
Bulk micromachining generally refers to processes involving wet chemical etching of structures formed out of the silicon substrate and so is limited to fairly large, crude structures. Surface micromachining allows intricate patterning of thin films of polysilicon and other materials to form essentially two-dimensional layered parts (since the thickness of the parts is limited by the thickness of the deposited films). There is a third type of micromachining in which the part is formed by filling a mold which was defined by photolithographic means. Historically micromachining molds have been formed in some sort of photopolymer, be it with x-ray lithography (``LIGA``) or more conventional UV lithography, with the aim of producing piece parts. Recently, however, several groups including ours at Sandia have independently come up with the idea of forming the mold for mechanical parts by etching into the silicon substrate itself. In Sandia`s mold process, the mold is recessed into the substrate using a deep silicon trench etch, lined with a sacrificial or etch-stop layer, and then filled with any of a number of mechanical materials. The completed structures are not ejected from the mold to be used as piece parts rather, the mold is dissolved from around selected movable segments of the parts, leaving the parts anchored to the substrate. Since the mold is recessed into the substrate, the whole micromechanical structure can be formed, planarized, and integrated with standard silicon microelectronic circuits before the release etch. In addition, unlike surface-micromachined parts, the thickness of the molded parts is limited by the depth of the trench etch (typically 10--50 {mu}m) rather than the thickness of deposited polysilicon (typically 2 {mu}m). The capability of fabricating thicker (and therefore much stiffer and more massive) parts is critical for motion-sensing structures involving large gimballed platforms, proof masses, etc.
As part of a research program in fire science and technology at Sandia National Laboratories (SNL), an experimental and computational investigation of the fire phenomenology associated with the presence of a large (3.66 m diameter), fuselage-sized cylindrical calorimeter engulfed in a large (18.9 m diameter) JP-8 pool fire subjected to high (10.2 m/s) winds were performed. The conditions investigated here resulted in a twofold increase in the incident heat flux to the surface of the object relative to heat fluxes typical of large hydrocarbon fires without engulfed objects. Due to the enhanced fuel/air mixing, enhanced turbulence, and larger flame volume, the highest heat fluxes are observed on the leeward side of the calorimeter. Radiative heat fluxes of 150--250 kW/m{sup 2} on this side, with the maximum heat flux occurring near the top of the calorimeter, were measured. Radiative heat fluxes of 60--200 kW/m{sup 2} were measured on the windward side, with the highest heat flux near the bottom of the calorimeter. Measured and predicted heat fluxes to the pool surface of 25--90 kW/m{sup 2} were observed. The presence of the calorimeter tends to decrease the overall fuel consumption rate primarily due to redirection of the flame zone away from the pool surface. Overall, the numerical models does a reasonable job of representing the essential features of the fire environment but under predicts the heat flux to the calorimeter. These results emphasize the importance of considering the wind-induced interaction of fires and large objects when estimating the incident heat fluxes on a engulfed object. The measurements and analyses are of particular interest since few studies to date have addressed cases where the fire and object are of comparable size.
This document presents an overview of the modifications that were done to the Finnigan MAT 271 mass spectrometer used in the Dept. 1823 Inorganic Gas Analysis Lab. Among the alterations to the spectrometer were addition of a new computer, interfaces to the power supply, addition of a multimeter and introduction of a Graphical User Interface software system to run the instrument. The impact of these improvements is also discussed. The appendix details a generic procedure for operating the instrument.
Beryllium because of its low atomic number and high thermal conductivity, is a candidate for both ITER first wall and divertor surfaces. This study addresses the following: why beryllium; design requirements for the ITER divertor; beryllium supply and unirradiated physical/mechanical property database; effects of irradiation on beryllium properties; tritium issues; beryllium health and safety; beryllium-coolant interactions and safety; thermal and mechanical tests; plasma erosion of beryllium; recommended beryllium grades for ITER plasma facing components; proposed manufacturing methods to produce beryllium parts for ITER; emerging beryllium materials; proposed inspection and maintenance techniques for beryllium components and coatings; time table and costs; and the importance of integrating materials and manufacturing personnel with designers.
This SAND report documents the results of an LDRD project undertaken to study the accuracy of terrain-aided navigation coupled with highly accurate topographic maps. A revolutionary new mapping technology, interferometric synthetic aperture radar (IFSAR), has the ability to make terrain maps of extremely high accuracy and spatial resolution, more than an order of magnitude better than currently available DMA map products. Using a laser altimeter and the Sandia Labs Twin Otter Radar Testbed, fix accuracies of less than 3 meters CEP were obtained over urban and natural terrain regions.
Organic inhibitors can be used to prevent corrosion of metals have application in the electronics industry as solderability preservatives. We have developed a model to describe the action of two inhibitors (benzotriazole and imidazole) during the environmental aging and soldering process. The inhibitors bond with the metal surface and form a barrier that prevents or retards oxidation. At soldering temperatures, the metal-organic complex breaks down leaving an oxide-free metal surface that allows excellent wetting by the molten solder. The presence of the inhibitor retards the wetting rate relative to clean copper but provides a vast improvement relative to oxidized copper.
This report summarizes work on the development of ultra-high-speed semiconductor optical and electronic devices. High-speed operation is achieved by velocity matching the input stimulus to the output signal along the device`s length. Electronic devices such as field-effect transistors (FET`s), should experience significant speed increases by velocity matching the electrical input and output signals along the device. Likewise, optical devices, which are typically large, can obtain significant bandwidths by velocity matching the light being generated, detected or modulated with the electrical signal on the device`s electrodes. The devices discussed in this report utilize truly distributed electrical design based on slow-wave propagation to achieve velocity matching.
This report describes the design and development activities that were involved in the SA3871 Intent Controller ASIC. The SA3871 is a digital gate array component developed for the MC4396 Trajectory Sensing Signal Generator for use in the B61-3/4/10 system as well as a possible future B61-MAST system.
This paper describes a product realization process developed at Sandia National Laboratories by the A-PRIMED project that integrates many of the key components of ``agile manufacturing`` into a complete, step-by-step, design-to-production process. For three separate product realization efforts, each geared to a different set of requirements, A-PRIMED demonstrated product realization of a custom device in less than a month. A-PRIMED used a discriminator (a precision electro-mechanical device) as the demonstration device, but the process is readily adaptable to other electro-mechanical products. The process begins with a qualified design parameter space. From that point, the product realization process encompasses all facets of requirements development, analysis and testing, design, manufacturing, robotic assembly and quality assurance, as well as product data management and concurrent engineering. In developing the product realization process, A-PRIMED employed an iterative approach whereby after each of three builds, the process was reviewed and refinements made on the basis of lessons learned. This paper describes the integration of project functions and product realization technologies, with references to reports detailing specific facets of the overall process. The process described herein represents the outcome of an empirically-based process development effort that on repeated iterations, was proven successful.
This report outlines the estimates that were made in 1992 of the potential load requirements for Boquillas del Carmen, a small Mexican village on the northern border of the state of Coahuila, Mexico near Big Bend National Park in southern Texas. The study was made to help determine the possibility that village might be electrified by solar or wind energy. Various estimates of are given of the potential load based on estimates ranging from basic use of lights, radio, television, and small household appliances to microwave ovens, refrigerators, and direct evaporative coolers. The low-energy consumption case was estimated to be at 23.0 kWh/month per residence per month, and the high-energy consumption case (with cooling) was 140.7 kWh/month per residence. On average, the typical residence is occupied by five individuals.
Large, three-dimensional enclosure radiation beat transfer problems place a heavy demand on computing resources such as computational cycles, memory requirements, disk I/O, and disk space usage. This is primarily due to the computational and memory requirements associated with the view factor calculation and subsequent access of the view factor matrix during solution of the radiosity matrix equation. This is a fundamental problem that constrains Sandia`s current modeling capabilities. Reducing the computational and memory requirements for calculating and manipulating view factors would enable an analyst to increase the level of detail at which a body could be modeled and would have a major impact on many programs at Sandia such as weapon and transportation safety programs, component survivability programs, energy programs, and material processing programs. CHAPARRAL is a library package written to address these problems and is specifically tailored towards the efficient solution of extremely large three-dimensional enclosure radiation heat transfer problems.
Evaluation of groundwater travel time (GWTT) is required as part of the investigation of the suitability of Yucca Mountain as a potential high-level nuclear-waste repository site. The Nuclear Regulatory Commission`s GWTT regulation is considered to be a measure of the intrinsic ability of the site to contain radionuclide releases from the repository. The work reported here is the first step in a program to provide an estimate of GWTT at the Yucca Mountain site in support of the DOE`s Technical Site Suitability and as a component of a license application. Preliminary estimation of the GWTT distribution in the unsaturated zone was accomplished using a numerical model of the physical processes of groundwater flow in the fractured, porous medium of the bedrock. Based on prior investigations of groundwater flow at the site, fractures are thought to provide the fastest paths for groundwater flow; conditions that lead to flow in fractures were investigated and simulated. Uncertainty in the geologic interpretation of Yucca Mountain was incorporated through the use of geostatistical simulations, while variability of hydrogeologic parameters within each unit was accounted for by the random sampling of parameter probability density functions. The composite-porosity formulation of groundwater flow was employed to simulate flow in both the matrix and fracture domains. In this conceptualization, the occurrence of locally saturated conditions within the unsaturated zone is responsible for the initiation of fast-path flow through fractures. The results of the GWTT-94 study show that heterogeneity in the hydraulic properties of the model domain is an important factor in simulating local regions of high groundwater saturation. Capillary-pressure conditions at the surface boundary influence the extent of the local saturation simulated.
Mission-directed public-sector research facilities are experiencing increasingly severe budget environments while seeing expanding missions and responsibilities. In an effort to identify research leveraging methodologies an information search was conducted in conjunction with some efforts to find the proper links to systems engineering fundamentals. The result is an initial model for use in a preconcept/phase-1 engineering design organization, with a goal of improving the organizations performance.
Systems Engineering is an interdisciplinary process that ensures that the customers` needs are satisfied throughout a system`s entire life cycle. This process includes: understanding customer needs; stating the problem; specifying requirements; defining performance and cost measures, prescribing tests, validating requirements, conducting design reviews, exploring alternative concepts, sensitivity analyses, functional decomposition, system design, designing and managing interfaces, system integration, total system test, configuration management, risk management, reliability analysis; total quality management; project management; and documentation. Material for this paper was gathered from senior Systems Engineers at Sandia National Laboratories.
The characterization of systems engineering as a discipline, process, procedure or a set of heuristics will have an impact on the implementation strategy, the training methodology, and operational environment. The systems engineering upgrade activities in the New Mexico Weapons Development Center and a search of systems engineering related information provides evidence of a degree of ambiguity in this characterization of systems engineering. A case is made in this article for systems engineering being the engineering discipline applied to the science of complexity. Implications of this characterization and some generic issues are delineated with the goal of providing an enterprise with a starting point for developing its business environment.
Inside Sandia, published every other month, presents technological advances made at Sandia National Laboratories. The articles in IS will cover a wide range of technologies that have been developed at Sandia. Some of the areas that will receive a good deal of attention in these pages include information sciences, manufacturing and robotics, environmental science, energy research, transportation technology, and biomedical engineering. All of this work is done to further Sandia National Laboratories` missions in defense, energy, and environmental research, and technology transfer.
The Department of Energy is conducting an ongoing investigation of the consequences of taking fuel burnup into account in the design of spent fuel transportation packages. A series of experiments, collectively called the Spent Fuel Safety Experiment (SFSX), has been devised to provide integral benchmarks for testing computer-generated predictions of spent fuel behavior. A set of experiments is planned in which sections of unirradiated fuel rods are interchanged with similar sections of spent PWR fuel rods in a critical assembly. By determining the critical size of the arrays, one can obtain benchmark data for comparison with criticality safety calculations. The SFSX provides a direct measurement of the reactivity effects of spent PWR fuel using a well-characterized, spent fuel sample. The SFSX also provides an experimental measurement of the end-effect, i.e., the reactivity effect of the variation of the burnup profile at the ends of PWR fuel rods. The design of the SFSX is optimized to yield accurate benchmark measurements of the effects of interest, well above experimental uncertainties.
Hypervelocity tests of spacecraft optical sensors were conducted to determine if the optical signature from an impact inside the optical sensor sunshade resembled signals that have been observed on-orbit. Impact tests were conducted in darkness and with the ejected debris illuminated. The tests were conducted at the Johnson Space Center Hypervelocity Impact Test Facility. The projectile masses and velocities that may be obtained at the facility are most representative of the hypervelocity particles thought to be responsible for a group of anomalous optical sensors responses that have been observed on-orbit. The projectiles are a few micrograms, slightly more massive than the microgram particles thought to be responsible for the signal source. The test velocities were typically 7.3 km/s, which are somewhat slower than typical space particles.
Successful robot systems must employ actions that are robust in the face of task uncertainty. Toward this end, Lozano-Perez, Mason, and Taylor developed a model of manipulation tasks that explicitly considers task uncertainty. In this paper we study the utility of this model applied to real-world tasks. We report the results of two experiments that highlight the strengths and weaknesses of the LMT approach. The first experiment showed that the LMT formalism can successfully plan solutions for a complex real-world task. The second experiment showed a task that the formalism is fundamentally incapable of solving.
Mass transport properties are important in polycrystalline materials used as protective films. Traditionally, such properties have been studied by examining model polycrystalline structures, such as a regular array of straight grain boundaries. However, these models do not account for a number of features of real grain ensembles, including the grain size distribution and the topological aspects of grain boundaries. In this study, a finite difference scheme is developed to study transient and steady-state mass transport through realistic two-dimensional polycrystalline microstructures. Effects of microstructural parameters such as average grain size and grain boundary topology are examined, as are effects due to limits of the model.
This paper presents some design considerations for small, flyback transformers used to charge energy storage capacitors to 0.1 to 5 KV from a low voltage DC source.
A numerical model for simulating the transient nonlinear behavior of 2-D viscous sloshing flows in rectangular containers subjected to arbitrary horizontal accelerations is presented. The potential-flow formulation uses Rayleigh damping to approximate the effects of viscosity, and Lagrangian node movement is used to accommodate violent sloshing motions. A boundary element approach is used to efficiently handle the time-changing fluid geometry. Additionally, a corrected equation is presented for the constraint condition relating normal and tangential derivatives of the velocity potential where the fluid free surface meets the rigid container wall. The numerical model appears to be more accurate than previous sloshing models, as determined by comparison against exact analytic solutions and results of previously published models.
The criminal justice projects at SNL include three projects for the National Institute of Justice (smart gun, restraining foam, aqueous foam, corrections perimeter), a Southwest Border study, and one involving corrections agencies. It is concluded that the national technologies developed to protect nuclear and other high value assets have enormous potential for application to crime and personal safety; the difficulty lies in simplifying the technology transfer and making the new systems affordable.
An overview of emissive display technologies is presented. Display types briefly described include: cathode ray tubes (CRTs), field emission displays (FEDs), electroluminescent displays (ELDs), and plasma display panels (PDPs). The critical role of phosphors in further development of the latter three flat panel emissive display technologies is outlined. The need for stable, efficient red, green, and blue phosphors for RGB fall color displays is emphasized.
Verification, calibration, and validation (VCV) of Computational Fluid Dynamics (CFD) codes is an essential element of the code development process. The exact manner in which code VCV activities are planned and conducted, however, is critically important. It is suggested that the way in which code validation, in particular, is often conducted--by comparison to published experimental data obtained for other purposes--is in general difficult and unsatisfactory, and that a different approach is required. This paper describes a proposed methodology for CFD code VCV that meets the technical requirements and is philosophically consistent with code development needs. The proposed methodology stresses teamwork and cooperation between code developers and experimentalists throughout the VCV process, and takes advantage of certain synergisms between CFD and experiment. A novel approach to uncertainty analysis is described which can both distinguish between and quantify various types of experimental error, and whose attributes are used to help define an appropriate experimental design for code VCV experiments. The methodology is demonstrated with an example of laminar, hypersonic, near perfect gas, 3-dimensional flow over a sliced sphere/cone of varying geometrical complexity.
The use of the NII (National Information Infrastructure) is growing rapidly in the number of users and in the areas in which it is being applied. Sandia is using, the NII to leverage the use of geographically distributed mechatronic (electromechanical) assets. This paper discusses the availability of networks, new challenges for robotics technology, and how the use of networks is helping to meet these challenges. A brief overview of the NII is provided, followed by a listing of ``needs`` within the intelligent systems community. An approach is then given for meeting, these needs and, finally, implementation, examples, and future research directions are discussed.
Recent worldwide events have shown that explosives are the weapon of choice of terrorists in a variety of situations. For this reason, the need exists to develop a walk-through explosives detector that can be used at airports, government buildings, and other sites requiring both high security and the rapid screening of large numbers of people. In this paper, we discuss on-going efforts at Sandia to develop a walk-through explosives detection portal for the Federal Aviation Administration (FAA). We present a brief overview of detectors and detection methods currently utilized in this field, and discuss the special challenges associated with the development of portal detectors. Preliminary results obtained with the portal system at Sandia indicate that the overall portal concept is viable for the detection of contraband high explosives.
The Long Range Video Observation Post (LRVOP) Project is a cooperative effort between the US and a Middle Eastern country to develop an improved version of their current video observation post. This project is part of a larger effort to cooperatively develop anti-terrorist technology. This particular equipment is required to facilitate the recording and identification of humans at a range of 1000 meters in day-light and 500 meters at night. The project objective was to take advantage of recent advances in camera technology, recorders, and image processing to provide an significant increase in performance with only a minimum increase in size, weight, and cost. The goal of the project was to convert the users general needs and desires into specific requirements that could be bid on by several companies. This paper covers the specific performance requirements, generally describe the components that might be used, and concentrate on describing the more difficult issues and technical challenges.
In the past many DOE and DoD facilities involved in handling nuclear material realized a need to enhance the safely and security for movement of sensitive materials within their facility, or ``intra-site``. There have been prior efforts to improve on-site transportation; however, there remains a requirement for enhanced on-site transportation at a number of facilities. The requirements for on-site transportation are driven by security, safety, and operational concerns. The Intra-site Secure Transport Vehicle (ISTV) was designed to address these concerns specifically for DOE site applications with a standardized vehicle design. This paper briefly reviews the ISTV design features providing significant enhancement of onsite transportation safety and security, and also describes the test and evaluation activities either complete of underway to validate the vehicle design and operation.
Thermal optimization procedures have been applied to determine the worst-case heating boundary conditions that a safety device can be credibly subjected to. There are many interesting aspects of this work in the areas of thermal transport, optimization, discrete modeling, and computing. The forward problem involves transient simulations with a nonlinear 3-D finite element model solving a coupled conduction/radiation problem. Coupling to the optimizer requires that boundary conditions in the thermal model be parameterized in terms of the optimization variables. The optimization is carried out over a diverse multi-dimensional parameter space where the forward evaluations are computationally expensive and of unknown duration a priori. The optimization problem is complicated by numerical artifacts resulting from discrete approximation and finite computer precision, as well as theoretical difficulties associated with navigating to a global minimum on a nonconvex objective function having a fold and several local minima. In this paper we report on the solution of the optimization problem, discuss implications of some of the features of this problem on selection of a suitable and efficient optimization algorithm, and share lessons learned, fixes implemented, and research issues identified along the way.
Single-walled carbon nanotube models have been constructed by insertion of 10-carbon bracelets into C{sub 70} to form C{sub 90} and C{sub 120}. Semiempirical heats of vicinal hydrogenation along the sides of the tubes are {approximately}40 kcal/mol more endothermic (less stable) than addition to the endcaps. Based on the similarity of the endcaps to C{sub 60}, hydrogenation of nanotubes is estimated to be approximately thermoneutral; therefore, only relatively high energy dienes or other species are likely to yield stable addended products.
A mechanical isolator has been developed for a piezoresistive accelerometer. The purpose of the isolator is to mitigate high frequency shocks before they reach the accelerometer because the high frequency shocks may cause the accelerometer to resonate. Since the accelerometer is undamped, it often breaks when it resonates. The mechanical isolator was developed in response to impact test requirements for a variety of structures at Sandia National Laboratories. An Extended Technical Assistance Program with the accelerometer manufacturer has resulted in a commercial isolator that will be available to the general public. This mechanical isolator has ten times the bandwidth of any other commercial isolator and has acceptable frequency domain performance from DC to 10 kHz ({plus_minus} 10%) over a temperature range of -65{degrees}F to +185{degrees}F as demonstrated in this paper.
Thermally activated (``thermal``) batteries have been used for ordnance applications (e.g., proximity fuzes) since World War II and, subsequent to that, in nuclear weapons. This technology was developed by the Germans as a power source for their V2 rockets. It was obtained by the Allies by interrogation of captured German scientists after the war. The technology developed rapidly from the initial primitive systems used by the Germans to one based on Ca/CaCrO{sub 4}. This system was used very successfully into the late 1970s, when it was replaced by the Li-alloy/FeS{sub 2} electrochemical system. This paper describes the predominant electrochemical couples that have been used in thermal batteries over the years. Major emphasis is placed on the chemistry and electrochemistry of the Ca/CaCrO{sub 4} and Li-alloy/FeS{sub 2} systems. The reason for this is to give the reader a better appreciation for the advances in thermal-battery technology for which these two systems are directly responsible. Improvements to date in the current Li-alloy/FeS{sub 2} and related systems are discussed and areas for possible future research and development involving anodes, cathodes, electrolytes, and insulations are outlined. New areas where thermal-battery technology has potential applications are also examined.
The current publicly released version of the Integrated TIGER Series (ITS), Version 3.0, has been widely distributed both domestically and internationally, and feedback has been very positive. This feedback as well as our own experience have convinced us to upgrade the system in order to honor specific user requests for new features and to implement other new features that will improve the physical accuracy of the system and permit additional variance reduction. This presentation we will focus on components of the upgrade that (1) improve the physical model, (2) provide new and extended capabilities to the three-dimensional combinatorial-geometry (CG) of the ACCEPT codes, and (3) permit significant variance reduction in an important class of radiation effects applications.
Several wellbore hydraulic models have been examined to determine their applicability in measuring the characteristics of lost circulation zones encountered in geothermal drilling. Characteristics such as vertical location in the wellbore, fracture size, effective permeability, and formation pressure must be known in order to optimize treatment of such zones. The models that have been examined to date are a steady-state model, a standpipe-pressure model, a raising-the-drill-bit model, a mud-weight model, a hydrofracture model, and several time-dependent models. None of these models yet have been found to adequately match the field data obtained from six loss zones in three geothermal wells. The development of these models is presented in this paper, and a discussion of their limitations is provided.
Oxide electrode technology is investigated for optimization of Pb(Zr,Ti)O{sub 3} (PZT) thin film capacitor properties for high density nonvolatile memory applications. PZT thin film capacitors with RF sputter deposited La{sub 0.5}Sr{sub 0.5}CoO{sub 3} (LSCO) electrodes have been characterized with respect to the following parameters: initial dielectric hysteresis loop characteristics, fatigue performance, microstructure and imprint behavior. Our studies have determined that the fatigue of PZT capacitors with LSCO electrodes is less sensitive to B site cation ratio and underlying electrode stack technology than with RuO{sub 2} electrodes. Doping PZT thin films with Nb (PNZT) improves imprint behavior of LSCO//PZT//LSCO capacitors considerably. We have demonstrated that PNZT 4/30/70 // LSCO capacitors thermally processed at either 550{degrees}C or 675{degrees}C have almost identical initial hysteresis properties and exhibit essentially no fatigue out to approximately 10{sup 10} cycles.
This paper describes a method for criticality control at fissile material storage facilities. The method involves the use criticiality indices for storage canisters. The logic, methodology, and results for selected canisters are presented. A concept for an interactive computer program using the method is also introduced. The computer program can be used in real time (using precalulated data) to select a Criticality Index (CI) for a container when it is delivered to or packaged at a site. Criticality safety is assured by controlling the sum of the CIs at each storage location below a defined Emit value when containers are moved.
The possibility of worker exposure to radioactive materials during accidents at nuclear facilities is a principal concern of the DOE. The KBERT software has been developed at Sandia National Laboratories under DOE support to address this issue by assisting in the estimation of risks posed by accidents at chemical and nuclear facilities. KBERT is an acronym for Knowledge-Based system for Estimating hazards of Radioactive material release Transients. The current prototype version of KBERT focuses on calculation of doses and consequences to in-facility workers due to accidental releases of radioactivity. This report gives detailed instructions on how a user who is familiar with the design, layout and potential hazards of a facility can use KBERT to assess the risks to workers in that facility. KBERT is a tool that allows a user to simulate possible accidents and observe the predicted consequences. Potential applications of KBERT include the evaluation of the efficacy of evacuation practices, worker shielding, personal protection equipment and the containment of hazardous materials.
An Image Compression and Authentication Module (ICAM) has been designed to perform the digitization, compression, and authentication of video images in a camera enclosure. The ICAM makes it possible to build video surveillance systems that protect the transmission and storage of video images. The ICAM functions with both NTSC 525 line and PAL 625 line cameras and contains a neuron chip (integrated circuit) permitting it to be interfaced with a local operating network which is part of the Modular Integrated Monitor System (MIMS). The MIMS can be used to send commands to the ICAM from a central controller or any sensor on the network. The ICAM is capable of working as a stand alone unit or it can be integrated into a network of other cameras. As a stand alone unit it sends its video images directly over a high speed serial digital link to a central controller for storage. A number of ICAMs can be multiplexed on a single coaxial cable. In this case, images are captured by each ICAM and held until the MIMS delivers commands for an individual image to be transmitted for review or storage. The ICAM can capture images on a time interval basis or upon receipt of a trigger signal from another sensor on the network. An ICAM which collects images based on other sensor signals, forms the basis of an intelligent {open_quotes}front end{close_quotes} image collection system. The burden of image review associated with present video systems is reduced by only recording the images with significant action. The cards used in the ICAM can also be used to decompress and display the compressed images on a NTSC/PAL monitor.
Coatings produced by feeding a steel wire into a high-velocity oxy-fuel (HVOF) torch are being intensively studied by the automotive industry as a cost-effective alternative to the more expensive cast iron sleeves currently used in aluminum engine blocks. The microstructure and properties of the sprayed coatings and the overall economics of the process depend critically on the melting and atomization occurring at the wire tip. This paper presents results characterizing several aspects of wire melting and droplet breakup in an HVOF device. Fluctuations in the incandescent emission of the plume one centimeter downstream from the wire tip were recorded using a fast photodiode. A Fourier transform of the light traces provided a measure of the stripping rate of molten material from the wire tip. Simultaneous in-flight measurement of atomized particle size and velocity distributions were made using a Phase Doppler Particle Analyzer (PDPA). The recorded size distributions approximate a log-normal distribution. Small particles traveled faster than large particles, but the difference was considerably smaller than simple aerodynamic drag arguments would suggest. A set of experiments was carried out to determine the effect that variations in torch gas flow rates have on wire melt rate, average particle size, and average particle velocity. The observed variation of particle size with spray condition is qualitatively consistent with a Weber breakup of the droplets coming off the wire. The measurements also showed that it was possible to significantly alter atomized particle size and velocity without appreciably changing the wire melt rate.
This paper discusses two commercially-available laser diagnostics that have been used in thermal spray research at Sandia National Laboratories: (1) a Phase Doppler Particle Analyzer (PDPA) and (2) a Laser Two-Focus (L2F) velocimeter. The PDPA provides simultaneous, correlated measurements of particle velocity and particle size distributions; but, particle sizing doesn`t work well with non-spherical particles or particles with rough surfaces. The L2F is used to collect particle velocity and number density distributions, and it can readily distinguish and separately measure particles with off-axis velocity vectors. PDPA and L2F principles of operation are presented along with potential advantages and limitations for thermal spray research. Four experiments were conducted to validate and compare measurement results with the PDPA and L2F instruments: (1) spinning wire, (2) powder in a High-Velocity Oxy-Fuel (HVOF) jet, (3) powder in a cold jet, and (4) droplets in a wire-fed HVOF jet. TWO DIFFERENT TYPES of commercially-available laser velocimeter systems, a Phase Doppler Particle Analyzer and a Laser-Two-Focus velocimeter have been used in the Thermal Spray Research Laboratory at Sandia National Laboratories. Each of these techniques has inherent advantages and limitations for thermal spray, and each involves assumptions that may not be valid for some experimental conditions. This paper describes operating principles and possible sources of measurement error for these two diagnostic systems. Some potential advantages and limitations are also presented. Four types of experiments were also conducted to validate and compare PDPA and L2F measurement results: (1) spinning wire, (2) powder in a High-Velocity Oxy-Fuel (HVOF) jet, (3) powder in a cold jet, and (4) droplets in a wire-fed HVOF jet. We also offer a few observations related to practical issues such as ease-of-use, reliability, and effects of dust and vibration in a thermal spray lab.
In the context of U.S. and Russian lab-to-lab initiatives, Sandia National Laboratories contracted with Kurchatov Institute Russian Research Center to demonstrate the feasibility of remotely monitoring the storage of nuclear material. The cooperative experiment was to demonstrate the Remote Monitoring System (RMS) with a minimum of 10 kg of HEU in storage at reciprocal facilities. The Kurchatov Institute selected a site at their facility and the DOE selected a site at the Argonne National Laboratory-West facility. At Kurchatov, there is material for monitoring in a floor vault, a cabinet, and shipping containers. At Argonne West, material stored in two types of storage systems is available for material monitoring. This paper discusses the system concept from both perspectives: the operator of a facility where a RMS is deployed and the user of the RMS at the remote site. The demonstration provides a unique opportunity to have a bilateral demonstration/evaluation where each participant examines all aspects of the system. The hardware and software needed to implement this system is discussed. The impacts to the operation of the facilities are discussed as well as the use of the system to remotely monitor a facility. This technology provides the capability of remotely monitoring the access to the stored nuclear materials but is not a real time security alarm system. Several enhancements to the Remote Monitoring System have been identified for future consideration.
The MIMS program is funded by the Department of Energy under the Office of Nonproliferation and National Security. The program objective is to develop cost effective, modular, multi-sensor monitoring systems. Both in-plant and ground based sensors are envisioned. It is also desirable to develop sensors/systems that can be fielded/deployed in a rapid fashion. A MIMS architecture was selected to allow modular integration of sensors and systems and is based on LonWorks technology, commercially developed by Echelon Corporation. The first MIMS fieldable hardware was demonstrated at Lawrence Livermore National Laboratory. The field test, known within the DOE as the Item Tracking and Transparency (IT&I) demonstration, involved the collaboration and cooperation of five DOE laboratories (Sandia (SNL), Lawrence Livermore (LLNL), Pacific Northwest (PNL), Los Alamos (LANL), and Oak Ridge (ORNL)). The IT&T demonstration involved the monitoring of special nuclear material as it was transported around the facility utilizing sensors from the participating labs. The scenario was programmed to ignore normal activity in the facility until entry into the room where the material was stored. A second demonstration, which involved three separate scenarios, was conducted at Idaho National Engineering Laboratory (INEL). The participants included representatives from SNL, LLNL, PNL, and INEL. DOE has selected INEL as the long term testbed for MIMS developed sensors, systems, and scenarios. This paper will describe the installation, intended purpose, and results of the field demonstrations at LLNL and INEL under the MIMS program.
A goal among many law enforcement and security professionals, and the National Institute of Justice, is to decrease the risk that an officer or security guard may encounter. One risk that officers confront is unpredictable persons who sometimes try to gain control of the officer`s firearm. The addition of user-recognizing-and-authorizing technologies to a firearm could eliminate the capability of an unauthorized user from firing an officer`s firearm. Sandia National Laboratories has been active in the research and development of nuclear security systems that include access and use control technologies. Sandia is being sponsored by the National Institute of Justice to perform a research and development project to determine the feasibility of a user authorized firearm, or {open_quotes}smart gun.{close_quotes} The focus group for the research is law enforcement officers because of the number of firearm take aways that have occurred in the past and the severe use requirements placed on their firearms. A comprehensive look at the problem of weapon take aways in the United States was conducted using information available from the Federal Bureau of Investigation and other law enforcement sources. An investigation into the end user requirements for smart gun technologies has been completed. During the remainder of the project, the user requirements are being transformed into engineering requirements. which will then be used to evaluate numerous technologies that could be used in a smart gun. Demonstration models will be made of the most promising technologies. Other potential applications are remote enabling and disabling of firearms, transportation of prisoners by corrections officers, military use in operations other than war, and use by private citizens.
A nonaqueous coprecipitation process has been developed to prepare controlled stoichiometry lithium manganese oxalate precipitates. The process involved mixing a methanolic Li-Mn nitrate solution with a methanolic solution containing tetramethylammonium oxalate as the precipitating agent. The resulting oxalates were readily converted to a variety of phase pure lithium manganese oxides at moderate temperatures ({le}600{degrees}C), where the phase formed was determined by the initial Li/Mn ratio in the starting solution. Metal cation dopants have been incorporated into the oxalate precipitate by dissolving the appropriate metal nitrate in the Li-Mn precursor solution The various starting solutions, oxalate precipitates, and calcined oxides have been extensively characterized using a variety of techniques, including {sup 7}Li NMR, TGA/DTA, SEM, and XRD. Results indicate that a strong interaction occurs between Li and Mn in the nitrate solution which carries over into the oxalate phase during precipitation. The morphology and the crystallite size of the oxide powders were shown to be controlled by the morphology of the oxalate precursor and the oxalate calcination temperature, respectively. The results of initial cathode performance tests with respect to dopant type (Al, Ni, Co) and concentration for LiMn{sub 2}O{sub 4} are also reported.
The Treaty on Open Skies has very specific requirements as a confidence building measure, but it could also serve as a component of an SNM Cutoff monitoring strategy. The participants to the Treaty are European countries, the United States, and Canada and would have to be extended to include other than the present signatories if it were to be used in a worldwide SNM verification Cutoff role. The major nuclear powers with the exception of China are signatories to the Treaty and the inclusion of other member states will only be considered once entry into force has started. The technology and data sharing provisions of the Treaty have defined the airborne sensor performance specifications. Therefore, the Treaty allowed sensor technology may not be adequate for the purposes of monitoring an SNM Cutoff regime. New sensors and sensor performance levels to adequately monitor an SNM Cutoff regime may be proposed only after entry into force of the Treaty on Open Skies. The utility of an aerial inspection component to the monitoring strategy for an SNM Cutoff regime would best be evaluated with field trials using realistic scenarios. This would allow the testing of synergism among other components of an overall monitoring strategy and would lend insight into the appropriate sensor technology to be recommended for future implementation.
While many techniques exist for production of soft tooling, for die casting there is limited recent experience with cast tooling. The most common US alloy used for manufacture of die casting tooling is wrought AISI H13. If the performance of the cast material is comparable to the wrought counterpart, the use of investment cast HI 3 tooling directly from patterns made via rapid prototyping is of considerable interest. A metallurgical study of investment cast H13 was conducted to evaluate the mechanical behavior in simulated die casting applications. Variable thickness plate investment castings of AISI H13 hot work die steel were produced and characterized in the as-cast and heat-treated conditions. The characterization included light microscopy and mechanical testing. Wrought samples of standard and premium grade H13 were heat-treated and characterized similarly for comparison. Microstructural differences were observed in as-cast samples produced in different section thicknesses. Dendrite cell size and carbide morphology constituted the most prominent microstructural differences observed. After a full heat-treatment, microstructural differences between the wrought material and cast materials were slight regardless of section thickness.The mechanical properties of the cast and heat-treated material proved similar to the properties of the standard heat-treated wrought material. A thermal fatigue testing unit was to con-elate the heat checking susceptibility of H13 steel to its processing and consequent microstructural condition. Surface hardness decreased significantly with thermal cycling, and heat checking was observed in as few as 50 cycles. Thermal softening and thermal fatigue susceptibility were quantified and discussed relative to the microstructural conditions created by processing and heat-treatment. It was found that the premium grade wrought H13 steel provided the best overall resistance to heat checking.
Changes in the reactant ion composition in the ion mobility spectrometer (IMS) can result in a change in the ionization processes occurring in the ionization region, ultimately leading to an altered instrumental response for the analyte, and exacerbating the problem of qualitative and quantitative analysis. Some species are very susceptible to changes in reactant ions, while other species are relatively unaffected. These types of behavior are observed for two common explosives, namely, hexahydro-1,3,5-trinitrol,3,5-triazine (RDX) and 1,3,5-trinitrotoluene (TNT), respectively. To control the reactant ion composition, and hence the gas phase chemistry, it is necessary to control the composition of gases present in the ionization region of the IMS. A series of modifications are described for the PCP Phemto-Chem 100 IMS that afford the requisite control. The effectiveness of these modifications for analysis of RDX and TNT are described and contrasted with that observed for the unmodified system.
Sputter deposition of ZnS:Mn/SrS:Ce multilayered broad-band ``white`` emission thin film electroluminescent (TFEL) stacks has been investigated. To date, deposition of these multilayers has been limited to vacuum evaporation techniques and atomic layer epitaxy, both of which require two different substrate temperatures for growth of high quality ZnS and SrS. This repeated thermal cycling during multilayer deposition can induce stress, defects, and interdiffusion with adversely affect EL performance. Sputter deposition of ZnS and SrS produces high quality TFELs for a wider range of substrate temperatures. Both materials can be sputter deposited at a common temperature (300-350{degrees}C) which eliminates the need for thermal cycling and increases manufacturability. Luminance outputs from sputter deposited ZnS and SrS thin films are comparable to those from evaporated films, making sputtering an attractive alternative deposition technique for these materials. We report on the effects of sputter deposition parameters including chamber pressure, substrate temperature, and H2S process gas partial pressure on the resultant composition and morphology of ZnS:Mn and SrS:Ce thin films and multilayers. Their EL performance was evaluated and correlated to composition and morphology.
This paper presents an overview of physical protection cooperation activities between Sandia (SNL) and the Former Soviet Union (FSU) regarding Material Protection Control and Accounting (MPC&A) responsibilities. Begun four years ago as part of the Safe, Secure Dismantlement Program, this project is intended to stem proliferation of weapons of mass destruction. Purpose of the program is to accelerate progress toward a goal shared by both Russia and the United States: to reduce the risk of nuclear weapons proliferation, including such threats as theft, diversion, and unauthorized possession of nuclear materials. This will be accomplished by strengthening the MPC&A systems in both, countries. This new program (US Department of Energy Laboratory-to-Laboratory MPC&A program) is designed to complement Government-to-Government programs sponsored by US Senators Nunn and Lugar. US and Russian representatives exchange visits and discuss physical protection philosophies. Russian representatives have received formal training in the US process of system design and analysis to include the design of an effective physical protection system, determination of physical protection system objectives, initial design of a physical protection system, evaluation of the design, and often redesign or refinement of the existing system. Some Russian organizations have philosophies similar to those of the United States, but when they differ, the US and Russian representatives must negotiate. Other Russian organizations, because of heavy reliance on guard forces, have not developed a systematic design process. Cooperative work between US national laboratories and Russian counterparts has resulted in major physical protection enhancements at a Russian demonstration site and other advancements for Laboratory-to-Laboratory projects.
The objective of this project is to develop novel catalysts for the direct conversion of natural gas to a liquid fuel. The current work investigates the use of biomimetic metalloporphyrins as catalysts for the partial oxidation of light alkanes to alcohols.
Long term mechanical creep and fatigue testing at elevated temperatures requires reliable systems with safeguards to prevent destruction of equipment, loss of data and negative environmental impacts. Toward this goal, a computer controlled system has been developed and built for interlocking tests run on elevated temperature mechanical test facilities. Sensors for water flow, water pressure, water leakage, temperature, power and hydraulic status are monitored to control specimen heating equipment through solid state relays and water solenoid valves. The system is designed to work with the default interlocks present in the RF generators and mechanical tests systems. Digital hardware consists of two National Instruments 1/0 boards mounted in a Macintosh IIci computer. Software is written in National Instruments LabVIEW. Systems interlocked include two MTS closed loop servo controlled hydraulic test frames, one with an RF generator and one with both an RF generator and a quartz lamp furnace. Control for individual test systems is modularized making the addition of more systems simple. If any of the supporting utilities fail during tests, heating systems, chill water and hydraulics are powered down, minimizing specimen damage and eliminating equipment damage. The interlock control is powered by an uninterruptible power supply. Upon failure the cause is documented in an ASCII file.
This document describes the processes to be used for creating corporate information systems within the scope of the Integrated information Services (IIS) Center. This issue A describes the Analysis and Implementation phases within the context of the entire life cycle. Appendix A includes a full set of examples of the analysis set deliverables. Subsequent issues will describe the other life cycle processes as we move toward enterprise-level management of information assets, including information meta-models and an integrated corporate information model. The analysis phase as described here, when combined with a specifications repository, will provide the basis for future reusable components and improve traceability of information system specifications to enterprise business rules.
In an R&D environment, Environmentally Conscious Manufacturing (ECM), which focuses on specific materials processing and manufacturing operations, can be used to bring about a broader objective: pollution prevention. Decreasing the impact a product or process has on the environment is quickly becoming the way to do business. In the past, the impact on the environment was considered separately from manufacturing processes. Now, companies are beginning to see the benefits of designing to minimize environmental impact. Incorporating upfront the process changes that reduce environmental impact offers improved process efficiency and long-term cost savings not only for manufacturing operations but also for R&D. Among the approaches used, all with the same objective of decreasing pollution and environmental impact from manufacturing or other business operations, are Environmentally Conscious Manufacturing (ECM), Design for Environment (DfE), and Pollution Prevention (P2).
The upwind leapfrog scheme for electromagnetic scattering is briefly described. Its application to the 3D Maxwell`s time domain equations is shown in detail. The scheme`s use of upwind characteristic variables and a narrow stencil result in a smaller demand in communication overhead, making it ideal for implementation on distributed memory parallel computers. The algorithm`s implementation on two message passing computers, a 1024-processor nCUBE 2 and a 1840-processor Intel Paragon, is described. Performance evaluation demonstrates that the scheme performs well with both good scaling qualities and high efficiencies on these machines.
We report on the optical and electrical characterization of aromatic, fluorinated, fully imidized, organic soluble, thermally and photochemically, crosslinkable, guest-host polyimides for integrated optics. Refractive indices and optical losses were measured to evaluate the performance of these materials for passive applications. Materials were doped with two high temperature nonlinear optical chromophores, and poled during crosslinking to produce nonlinear optical materials. Measurements of electro-optic coefficient, macroscopic second order susceptibility, and conductivity were performed to assess these materials as potential candidates for active devices.
Numerical simulations of dynamic uniaxial strain loading of fiber-reinforced composites are presented that illustrate the wide range of deformation mechanisms that can be captured using a micromechanics-based homogenization technique as the material model in existing continuum mechanics computer programs. Enhancements to the material model incorporate high strain-rate plastic response, elastic nonlinearity, and rate-dependent strength degradation due to material damage, fiber debonding, and delamination. These make the model relevant to designing composite structural components for crash safety, armor, and munitions applications.
Different solderability tests have been developed to determine the wetting behavior of solder on metallic surfaces. None offer an exact measure of capillary flow associated with conventional mixed technology soldering. With shrinking package designs, increasing reliability requirements, and the emergence of new soldering technologies, there is a growing need to better understand and predict the flow of solder on printed wiring board (PWB) surfaces. Sandia National Laboratories has developed a capillary flow solderability test, through a joint effort with the National Center for Manufacturing Sciences, that considers this fundamental wetting issue for surface mount technology. The test geometry consists of a metal strip (width, {delta}) connected to a circular metal pad (radius, r{sub c}). Test methodology, experimental results, and validation of a flow model are presented in this paper.
Streak camera based diagnostics are vital to the inertial confinement fusion program at Sandia National Laboratories. Performance characteristics of various readout systems coupled to an EGG-AVO streak camera were analyzed and compared to scaling estimates. The purpose of the work was to determine the limits of the streak camera performance and the optimal fielding conditions for the Amador Valley Operations (AVO) streak camera systems. The authors measured streak camera limitations in spatial resolution and sensitivity. Streak camera limits on spatial resolution are greater than 18 lp/mm at 4% contrast. However, it will be difficult to make use of any resolution greater than this because of high spatial frequency variation in the photocathode sensitivity. They have measured a signal to noise of 3,000 with 0.3 mW/cm{sup 2} of 830 nm light at a 10 ns/mm sweep speed. They have compared lens coupling systems with and without micro-channel plate intensifiers and systems using film or charge coupled device (CCD) readout. There were no conditions where film was found to be an improvement over the CCD readout. Systems utilizing a CCD readout without an intensifier have comparable resolution, for these source sizes and at a nominal cost in signal to noise of 3, over those with an intensifier. Estimates of the signal-to-noise for different light coupling methods show how performance can be improved.
In July, 1994, a team of materials specialists from Sandia and U S Industry traveled to Russia and the Ukraine to select and fund projects in materials and process technology in support of the Newly Independent States/Industrial Partnering Program (NIS/IPP). All of the projects are collaborations with scientists and Engineers at NIS Institutes. Each project is scheduled to last one year, and the deliverables are formatted to supply US Industry with information which will enable rational decisions to be made regarding the commercial value of these technologies. This work is an unedited interim compilation of the deliverables received to date.
This report summarizes a Sandia program that included partnerships with Lawrence Livermore National Laboratory and Synthetica Technologies, Inc. to design and test a steam reforming system for treating Hanford underground storage tank (UST) wastes. The benefits of steam reforming the wastes include the resolution of tank safety issues and improved radionuclide separations. Steam reforming destroys organic materials by first gasifying, then reacting them with high temperature steam. Tests indicate that up to 99% of the organics could be removed from the UST wastes by steam exposure. In addition, it was shown that nitrates in the wastes could be destroyed by steam exposure if they were first distributed as a thin layer on a surface. High purity alumina and nickel alloys were shown to be good candidates for materials to be used in the severe environment associated with steam reforming the highly alkaline, high nitrate content wastes. Work was performed on designing, building, and demonstrating components of a 0.5 gallon per minute (gpm) system suitable for radioactive waste treatment. Scale-up of the unit to 20 gpm was also considered and is feasible. Finally, process demonstrations conducted on non-radioactive waste surrogates were carried out, including a successful demonstration of the technology at the 0.1 gpm scale.
A methodology for risk management in the design of software systems is presented. It spans security, safety, and correct operation of software within the context of its environment, and produces a risk analysis and documented risk management strategy. It is designed to be iteratively applied, to attain appropriate levels of detail throughout the analysis. The methodology and supporting tools are discussed. The methodology is critiqued relative to other research in the field. Some sample applications of the methodology are presented.
Both the Intelligent Transportation Systems (ITS) and National Information Infrastructure (NU) efforts have ambitious goals that are expected to improve the fundamental infrastructure, commerce, and society of the United States. Achieving these goals will require rapid development and deployment of information compatibility methods through technical and institutional standards. These standards will have to be scaleable and flexible to support new, and as-yet-undiscovered, data. Yet they will also need to accommodate our valuable data reserves. The area of geospatial data, and thus the creation of a National Spatial Data Infrastructure (NSDI), is particularly challenging due to the profoundly different forms, evolutionary histories, and meanings attached to spatial data. We discuss technical issues resulting from the different natures and inaccuracy of existing geodata, and areas where federal policy could lead the way to greater compatibility.
As a result of a number of events the inventory of fissile materials no longer in nuclear weapons in the United States is increasing. This has led to a growing concern regarding the potential for theft and/or diversion and accountability of this material. Straight-Line is a project whose purpose is to demonstrate a site-independent system to monitor stored nuclear material (e.g. plutonium) and integrate the collection, processing and dissemination of information regarding this material. Safeguards and security (S&S) goals of this project include data transfer of information on nuclear material to appropriate users to enhance S&S, continuous on-line accountability, reduction of hands-on access to nuclear materials, incorporation of information security technologies, and early detection of tampering or unauthorized material movement. This paper addresses threat considerations, S&S requirements, S&S objectives, and issues for the Straight-Line project. S&S features and benefits of this project are discussed with respect to existing item monitoring systems and/or other material tracking systems being developed.
There are several distinctive types of coring-induced fractures that can be recognized in core on the basis of morphology, assisted by certain characteristics such as edge effects and surface ornamentation. The shape and orientation of many of these induced fractures offer information on the in-situ stress conditions and the coring process. Petal, petal-centerline, scribe-knife, disc, and torque-related fractures may all be caused by coring in vertical wells. Saddle fractures, (related to petal fractures) are unique to horizontal core, as is the polishing of fracture surfaces during coring. other features such as scribe-line rotation, hammer marks, and rotary-bit patterns are important in making correct interpretations of the in situ stress and reservoir permeability, and in making the maximum use of the evidence bearing on reservoir fracture-system permeability provided by both induced and natural fractures.
Sandia National Laboratories Annular Core Research Reactor (ACRR) is undertaking a new mission for the Department of Energy: production of the radioisotope {sup 99}Mo used in nuclear medicine applications. Isotope production is significantly different from previous programs conducted at the ACRR that typically required high intensity, short duration pulses. The current UO{sub 2}-BeO fuel will power the initial startup phase of the production program, and can perform exceptionally well for this mission. However, this type of fuel is no longer available, commercially or otherwise. This paper presents the results of some preliminary studies of commercially available fuels.
Formal interactions with Kurchatov Institute (KI) began summer 1994 on material protection, control and accountability (MPC&A). Contracts were placed by LANL and Sandia with KI to implement a nuclear material accounting system and a physical security system at a KI demonstration facility which contain two critical assemblies with special nuclear material. LLNL implemented May 1995 a task to measure by gamma-ray spectroscopy the uranium enrichment of fuel in the facility. This laboratory-to-laboratory effort is part of the cooperative program between US and Russian institutes in nuclear material nonproliferation. In 1994-5, KI personnel demonstrated the physical security system. The next facility for work in MPC&A at KI is the Central Storage Facility, which is important for the computerized material accounting system for KI.
EcoSys is an environmental decision support tool to assist in the design of green products and process. EcoSys consist of an information and expert system that contains input from experts in products, processes and the environment as well as a flexible, goal driven, rule based decision model that can accommodate many environmental management perspectives. This includes allowing specific users to specify weighting factors for the impact decision model. This tool is extensible in that it can be utilized within the boundaries of a company and migrated to include suppliers and customers until full life cycles are assessed. We discussed the details and use of the environmental models available for the experts. We also showed how interviews with manufacturing experts led to the design of a goal-driven rule based reasoning system to support the problem solving. Finally, we offered a number of examples that detailed the types of analysis possible with EcoSys. Our ongoing work is to increase the precision of the environmental attributes database and to extend the product-process database to support a wider set of product analyses. Based on user feedback, we are also continuing to improve the X-Window user interface.
Three sets of rock samples have been subjected to planar impact to characterize loading, Hugoniot and release responses. A slate form Pennsylvania was tested over the stress range of 5 GPa to 140 GPa. Phyllite from the Lupin Mine (Canada) was tested over the 14--50 GPa stress region. Finally, granite samples from the SHIST test site (New Mexico) were tested over the 10--20 GPa stress region. The granite tests included a transmitted-wave experiment at about 10 GPa. In 12 of the 13 tests, a reverse-ballistic configuration (optimized for Hugoniot and release measurements) was used. The remaining test (conducted on the granite) provided a transmitted waveform from which precursor, Hugoniot and release properties were obtained. Velocity interferometry (VISAR) was used as the primary diagnostic throughout. The slate data showed an unexpected inflection downward in the Hugoniot at around 8 GPa. The slate and granite showed release paths lying below the Hugoniot for lower stress levels (below {approx} 60 GPa), while the slate release paths were ``normal`` (above the Hugoniot) at higher stress levels. In addition, the granite releases were found to lie substantially below the Hugoniot in the 30--40 GPa region; this may be related to the quartz-stishovite transition. The present results are generally consistent with earlier work.
We report on experimental measurements and numerical predictions of shear-induced migration of particles in concentrated suspensions subjected to flow in the wide gap between a rotating inner cylinder placed eccentrically within a fixed outer cylinder (a cylindrical bearing). The suspensions consists of large, noncolloidal spherical particles suspended in a viscous Newtonian liquid. Nuclear magnetic resonance (NMR) imaging is used to measure the time evolution of concentration and velocity profiles as the flow induced particle migration from the initial, well-mixed state. A model originally proposed by Phillips et al. (1992) is generalized to two dimensions. The coupled equations of motion and particle migration are solved numerically using an explicit pseudo-transient finite volume formulation. While not all of the qualitative features observed in the experiments are reproduced by this general numerical implementation, the velocity predictions show moderately good agreement with the experimental data.
Prototype circuit board test vehicles wee assembled with three candidate lead-free solders: 96.5Sn-3.5Ag (wt %), 58Bi-42Sn, and 91.84Sn-3.33 Ag 83Bi., using a forced-convection/infrared furnace and RMA flux based pastes. Wettability of circuit board features and packages was best with Sn-Ag-Bi alloy followed in order by Bi-Sn and Sn-Ag solders. The Sn-Ag-Bi solder had a greater propensity for void formation in the joints. The reliability assessment was based upon solder joint microstructure and the shear strength of selected leadless packages. Solder joint damage was of a greater extent after thermal shock exposures rather than thermal cycling. The Sn-Ag-Bi alloy on the largest package appeared most susceptible to thermal shock. Test vehicle performance clearly demonstrated that, with the non-lead solders, local thermal expansion mismatch can be as detrimental to joint integrity as the traditional global mismatch damage.
The manufacturing feasibility and attachment reliability of a series of newly developed lead-free solders were investigated for wave soldering applications. Some of the key assembly aspects addressed included: wettability as a function of board surface finish, flux activation and surface tension of the molten solder, solder joint fillet quality and optimization of soldering thermal profiles. Generally, all new solder formulations exhibited adequate wave soldering performance and can be considered as possible alternatives to eutectic SnPb for wave soldering applications. Further process optimization and flux development is necessary to achieve the defect levels associated with the conventional SnPb process.
Variable thickness plate investment castings of AISI H13 hot work die steel were pour and characterized in the as-cast and heat treated conditions. The characterization included light microscopy and mechanical testing. Wrought samples of standard and premium grade H13 steel were heat treated and characterized similarly for comparison. Microstructural differences were observed in as-cast samples poured to different section thicknesses. Dendrite cell size and carbide morphology constituted the most prominent microstructural differences observed. After a full heat treatment, however, Microstructural differences between the wrought material and cast materials were slight regardless of section thickness. The mechanical properties of the cast and heat treated material proved similar to the properties of the standard heat treated wrought material. A thermal fatigue testing unit was designed and built to correlate the heat checking susceptibility of AISI H13 steel to its processing and consequent microstructural condition. Surface hardness decreased significantly with thermal cycling, and heat checking was noticed in as few as 50 cycles. Thermal softening and thermal fatigue susceptibility were quantified and discussed relative to the microstructural conditions created by processing and heat treatment. It was found that the premium grade wrought H13 steel provided the best overall resistance to heat checking; however, the heat-treat cast and as-cast H13 tool steel (made from standard grade wrought H13 tool steel) provided comparable resistance to heat checking in terms Of area fraction of heat checking and maximum crack length.