Fiberglass tape and borosilicate filter discs impregnated with molten LiCl-KCl eutectic were examined for potential use as separators for high-temperature LiSi/LiCl-KCl/FeS{sub 2} thermal batteries. Test discs were punched from these materials and evaluated at 400 C in single cells at a steady-state current of 63 mA/cm{sup 2}. The performance generally improved with electrolyte loading for most of the materials. Better results were obtained with the filter discs than with the tape. The best overall results were obtained with Whatman GF/A discs. Active lives for cells with these separators were about 85% of the standard cells with pressed-powder separators. More work with other materials and electrolytes over a wider temperature range is underway, along with 5-cell-battery tests.
Thin-film electrodes of a plasma-sprayed Li-Si alloy were evaluated for use as anodes in high-temperature thermally activated (thermal) batteries. These anodes were prepared using 44% Li/56% Si (w/w) material as feed material in a special plasma-spray apparatus under helium or hydrogen, to protect this air- and moisture-sensitive material during deposition. Anodes were tested in single cells using conventional pressed-powder separators and lithiated pyrite cathodes at temperatures of 400 to 550 C at several different current densities. A limited number of 5-cell battery tests were also conducted. The data for the plasma-sprayed anodes was compared to that for conventional pressed-powder anodes. The performance of the plasma-sprayed anodes was inferior to that of conventional pressed-powder anodes, in that the cell emfs were lower (due to the lack of formation of the desired alloy phases) and the small porosity of these materials severely limited their rate capability. Consequently, plasma-sprayed Li-Si anodes would not be practical for use in thermal batteries.
High temperature XRD has been employed to monitor the devitrification of Dupont 951 low temperature co-fired ceramic (LTCC) and Dupont E84005 resistor ink. The LTCC underwent devitrification to an anorthite phase in the range of 835-875 C with activation energy of 180 kJ/mol as calculated from kinetic data. The resistor paste underwent devitrification in the 835-875 C range forming monoclinic and hexagonal celcian phases plus a phase believed to be a zinc-silicate. RuO{sub 2} appeared to be stable within this devitrified resistor matrix. X-ray radiography of a co-fired circuit indicated good structural/chemical compatibility between the resistor and LTCC.
We have discovered that small polyols are reasonably effective at stabilizing colloidal silica against aggregation, even under the conditions of high pH and salt concentration. Both quasielastic and elastic light scattering were used to show that these polyols dramatically decrease the aggregation rate of the suspension, changing the growth kinetics from diffusion-limited cluster-cluster aggregation to reaction-limited cluster-cluster aggregation. These polyols maybe useful in the treatment of tank wastes at the Hanford site.
This paper presents a new technique for automatically detecting interval constraints for swept volumes with holes. The technique finds true volume constraints that are not necessarily imposed by the surfaces of the volume. A graphing algorithm finds independent, parallel paths of edges from source surfaces to target surfaces. The number of intervals on two paths between a given source and target surface must be equal; in general, the collection of paths determine a set of linear constraints. Linear programming techniques solve the interval assignment problem for the surface and volume constraints simultaneously.
The model parameters for the normalized 1054V1 material were compared to parameters previously generated for 1026 steel, and the transformation behavior was relatively consistent. Validation of the model predictions by heating into the austenite plus undissolved ferrite phase field and rapidly quenching resulted in reasonable predictions when compared to the measured volume fractions from optical metallography. The hot rolled 1054V1 material, which had a much coarser grain size and a non-equilibrium volume fraction of pearlite, had significantly different model parameters and the on heating transformation behavior of this material was less predictable with the established model. The differences in behavior is consistent with conventional wisdom that normalized micro-structure produce a more consistent response to processing, and it reinforces the need for additional work in this area.
We present a microelectronics fabrication compatible process that comprises photolithography and a key room temperature SiON thin film plasma deposition to define and seal a fluidic microduct network. Our single wafer process is independent of thermo-mechanical material properties, particulate cleaning, global flatness, assembly alignment, and glue medium application, which are crucial for wafer fusion bonding or sealing techniques using a glue medium. From our preliminary experiments, we have identified a processing window to fabricate channels on silicon, glass and quartz substrates. Channels with a radius of curvature between 8 and 50 {micro}m, are uniform along channel lengths of several inches and repeatable across the wafer surfaces. To further develop this technology, we have begun characterizing the SiON film properties such as elastic modulus using nanoindentation, and chemical bonding compatibility with other microelectronic materials.
In 1975 Sandia National Laboratories (SNL) was asked by the predecessor to the Department of Energy to assume responsibility for the scientific programs necessary to assure the safe and satisfactory development of a geologic repository in the salt beds of southeast New Mexico. Sandia has continued in the role of Science Advisor to the Waste Isolation Pilot Plant (WIPP) to the present time. This paper will share the perspectives developed over the past 25 years as the project was brought to fruition with successful certification by the Environmental Protection Agency (EPA) on May 13, 1998 and commencement of operations on April 26, 1999.
The Federal Aviation Administration's Airworthiness Assurance NDI Validation Center (AANC) is currently conducting experiments with Level 4, Method B penetrant on low cycle fatigue specimens. The main focus of these experiments is to document the affect on penetrant brightness readings by varying inspection parameters. This paper discusses the results of changing drying temperature, drying time, and dwell time of both penetrant and emulsifier on low cycle fatigue specimens.
Frequency-domain shot-record migration can produce higher quality images than Kirchhoff migration but typically at a greater cost. The computational cost of shot-record migration is the product of the number of shots in the survey and the expense of each individual migration. Many attempts to reduce this cost have focused on the speed of the individual migrations, trying to achieve a better trade-off between accuracy and speed. Another approach is to reduce the number of migrations. We investigate the simultaneous migration of shot records using frequency-domain shot-record migration algorithms. The difficulty with this approach is the production of so-called cross terms between unrelated shot and receiver wavefields, which generate unwanted artifacts or noise in the final image. To reduce these artifacts and obtain an image comparable in quality to the single-shot-per-migration result, we have introduced a process called phase encoding which shifts or disperses these cross terms. The process of phase encoding thus allows one to trade signal-to-noise ratio for the speed of migrating the entire survey. Several encoding functions and two application strategies have been tested. The first strategy, combining multiple shots per migration and using each shot only once, provides a reduction in computation directly related to the number of shots combined. The second strategy, performing multiple migrations of all the shots in the survey, provides a means to reduce the cross-term noise through stacking the resulting images. The additional noise in both strategies may be tolerated if it is no stronger than the inherent seismic noise in the migrated image, and if the final image is achieved with less cost.
Uranium fragments from the Sandia Sled Track were studied as analogues for weapons components and depleted uranium buried at the Greater Confinement Disposal (GCD) site in Nevada. The Sled Track uranium fragments originated as weapons mockups and counterweights impacted on concrete and soil barriers, and experienced heating and fragmentation similar to processes thought to affect the Nuclear Weapons Accident Residues (NWAR) at GCD. Furthermore, the Sandia uranium was buried in unsaturated desert soils for 10 to 40 years, and has undergone weathering processes expected to affect the GCD wastes. Scanning electron microscopy, X-ray diffraction and microprobe analyses of the fragments show rapid alteration from metals to dominantly VI-valent oxy-hydroxides. Leaching studies of the samples give results consistent with published U-oxide dissolution rates, and suggest longer experimental periods (ca. 1 year) would be required to reach equilibrium solution concentrations. Thermochemical modeling with the EQ3/6 code indicates that the uranium concentrations in solutions saturated with becquerelite could increase as the pore waters evaporate, due to changes in carbonate equilibria and increased ionic strength.
This Sandia National Laboratories/New Mexico Environmental Information Document (EID) compiles information on the existing environment, or environmental baseline, for SNUNM. Much of the information is drawn from existing reports and databases supplemented by new research and data. The SNL/NM EID, together with the Sandia National Laboratories/New Mexico Facilities and Safety Information Document, provide a basis for assessing the environment, safety, and health aspects of operating selected facilities at SNL/NM. The environmental baseline provides a record of the existing physical, biological, and socioeconomic environment at SNL/NLM prior to being altered (beneficially or adversely) by proposed programs or projects. More specifically, the EID provides information on the following topics: Geology; Land Use; Hydrology and Water Resources; Air Quality and Meteorology; Ecology; Noise and Vibration; Cultural Resources; Visual Resources; Socioeconomic and Community Services; Transportation; Material Management; Waste Management; and Regulatory Requirements.
Sandia National Laboratories/New Mexico (SNL/NM) is operated in support of the US Department of Energy (DOE) mission to provide weapon component technology and hardware for national security needs. SNL/NM also conducts fundamental research and development to advance technology in energy research, computer science, waste management, microelectronics, materials science, and transportation safety for hazardous and nuclear components. In support of SNL's mission, the Environment, Safety and Health (ES&H) Center and the Environmental Restoration (ER) Project at SNL/NM have established extensive environmental programs to assist SNL's line organizations in meeting all applicable local, State, and Federal environmental regulations and DOE requirements. This annual report for calendar year 1998 (CY98) summarizes the compliance status of environmental regulations applicable to SNL site operations. Environmental program activities include terrestrial surveillance; ambient air and meteorological monitoring hazardous, radioactive, and solid waste management; pollution prevention and waste minimization; environmental remediation; oil and chemical spill prevention; and National Environmental Policy Act (NEPA) activities. This report has been prepared in compliance with DOE Order 5400.1, General Environmental Protection Program (DOE 1990).
Sandia National Laboratories (SNL) operates the Tonopah Test Range (TTR) for the Department of Energy (DOE) Weapons Ordnance Program. This annual report (calendar year 1998) summarizes the compliance status to environmental regulations applicable at the site including those statutes that govern air and water quality, waste management cleanup of contaminated areas, control of toxic substances, and adherence to requirements as related to the National Environmental Policy Act (NEPA). In compliance with DOE orders, SNL also conducts environmental surveillance for radiological and nonradiological contaminants. SNL's responsibility for environmental surveillance at TTR extends only to those areas where SNL activities are carried out. Annual radiological and nonradiological routine releases and unplanned releases (occurrences) are also summarized. This report has been prepared in accordance with DOE Order 5400.1, General Environmental Protection Program (DOE 1990a).
Use of Gulf Coast salt domes for construction of very large storage caverns by solution mining has grown significantly in the last several decades. In fact, among the largest developers of storage caverns along the Gulf Coast is the Strategic Petroleum Reserve (SPR) which has purchased or constructed 62 crude oil storage caverns in four storage sites (domes). Although SPR and commercial caverns have been operated economically for many years, the caverns still exhibit some relatively poorly understood behaviors, especially involving creep closure volume loss and hanging string damage from salt falls. Since it is possible to postulate that some of these behaviors stem from geomechanical or reformational aspects of the salt, a method of correlating the cavern response to mechanical creep behavior as determined in the laboratory could be of considerable value. Recently, detailed study of the creep response of domal salts has cast some insight into the influence of different salt origins on cavern behavior. The study used a simple graphical analysis of limited non-steady state data to establish an approach or bound to steady state, as an estimate of the steady state behavior of a given salt. This permitted analysis of sparse creep databases for domal salts. It appears that a shortcoming of this steady state analysis method is that it obscures some critical differences of the salt material behavior. In an attempt to overcome the steady state analysis shortcomings, a method was developed based on integration of the Multimechanism-Deformation (M-D) creep constitutive model to obtain fits to the transient response. This integration process permits definition of all the material sensitive parameters of the model, while those parameters that are constants or material insensitive parameters are fixed independently. The transient analysis method has proven more sensitive to differences in the creep characteristics and has provided a way of defining different behaviors within a given dome. Characteristics defined by the transient analysis are related quantitatively to the volume loss creep rate of the SPR caverns. This increase in understanding of the domal material creep response already has pointed to the possibility y of delineating the existence of material spines within a specific dome. Further definition of the domal geology and structure seems possible only through expansion of the creep databases for domal salts.
The Puerto Rico Electric Power Authority (PREPA) installed a distributed battery energy storage system in 1994 at a substation near San Juan, Puerto Rico. It was patterned after two other large energy storage systems operated by electric utilities in California and Germany. The U.S. Department of Energy (DOE) Energy Storage Systems Program at Sandia National Laboratories has followed the progress of all stages of the project since its inception. It directly supported the critical battery room cooling system design by conducting laboratory thermal testing of a scale model of the battery under simulated operating conditions. The Puerto Rico facility is at present the largest operating battery storage system in the world and is successfully providing frequency control, voltage regulation, and spinning reserve to the Caribbean island. The system further proved its usefulness to the PREPA network in the fall of 1998 in the aftermath of Hurricane Georges. The owner-operator, PREPA, and the architect/engineer, vendors, and contractors learned many valuable lessons during all phases of project development and operation. In documenting these lessons, this report will help PREPA and other utilities in planning to build large energy storage systems.
In order to understand the hindered rotational and vibrational dynamics of methane trapped in C{sub 60} interstices and to determine the structure around the interstitial site, they have carried out inelastic neutron scattering studies of the methane/C{sub 60} system. At temperatures of 20K and below, they observe inelastic peaks from rotational transitions of the CH{sub 4}. These transitions allow unambiguous assignment of the hindered rotational energy levels and a determination of the interaction potential. The appearance of two peaks for one of the J = 0{r_arrow}3 transitions implies the existence of two distinct kinds of interstitial sites and the measured transition energies suggest a rotational barrier of about 26 and 16 meV for these sites. Time-dependent changes in peak heights indicate slow t{sub 1/2} ({approx} 2.6 hrs) triplet{r_arrow}quintet nuclear spin conversion that necessarily accompanies the J = 1{r_arrow}0 rotational relaxation. They also have observed a sharp inelastic peak at 9.3 meV, which corresponds to a local vibrational mode of CH{sub 4} rattling in its cage at {approximately} 2.2 THz. Other peaks involving higher-energy vibrational excitations in CD{sub 4}/C{sub 60} correspond in energy to assigned peaks in the inelastic neutron scattering spectra of C{sub 60}, albeit sometimes with different intensities.
The methodology in this report improves on some of the limitations of many conventional safety assessment and decision analysis methods. A top-down mathematical approach is developed for decomposing systems and for expressing imprecise individual metrics as possibilistic or fuzzy numbers. A ''Markov-like'' model is developed that facilitates combining (aggregating) inputs into overall metrics and decision aids, also portraying the inherent uncertainty. A major goal of Markov modeling is to help convey the top-down system perspective. One of the constituent methodologies allows metrics to be weighted according to significance of the attribute and aggregated nonlinearly as to contribution. This aggregation is performed using exponential combination of the metrics, since the accumulating effect of such factors responds less and less to additional factors. This is termed ''soft'' mathematical aggregation. Dependence among the contributing factors is accounted for by incorporating subjective metrics on ''overlap'' of the factors as well as by correspondingly reducing the overall contribution of these combinations to the overall aggregation. Decisions corresponding to the meaningfulness of the results are facilitated in several ways. First, the results are compared to a soft threshold provided by a sigmoid function. Second, information is provided on input ''Importance'' and ''Sensitivity,'' in order to know where to place emphasis on considering new controls that may be necessary. Third, trends in inputs and outputs are tracked in order to obtain significant information% including cyclic information for the decision process. A practical example from the air transportation industry is used to demonstrate application of the methodology. Illustrations are given for developing a structure (along with recommended inputs and weights) for air transportation oversight at three different levels, for developing and using cycle information, for developing Importance and Sensitivity measures for soil aggregation, for developing dependence methodology, for constructing early alert logic, for tracking trends, for relating the Markov model to other (e.g., Reason) models, for developing and demonstrating rudimentary laptop software, and for developing an input/output display methodology.
Mechanical and hydrological properties of rock salt provide excellent bases for geological isolation of hazardous materials. Regulatory compliance determinations for the Waste Isolation Pilot Plant (WIPP) stand as testament to the widely held conclusion that salt provides excellent isolation properties. The WIPP saga began in the 1950s when the U.S. National Academy of Sciences (NAS) recommended a salt vault as a promising solution to the national problem of nuclear waste disposal. For over 20 years, the Scientific basis for the NAS recommendation has been fortified by Sandia National Laboratories through a series of large scale field tests and laboratory investigations of salt properties. These scientific investigations helped develop a comprehensive understanding of salt's 4 reformational behavior over an applicable range of stresses and temperatures. Sophisticated constitutive modeling, validated through underground testing, provides the computational ability to model long-term behavior of repository configurations. In concert with advancement of the mechanical models, fluid flow measurements showed not only that the evaporite lithology was essentially impermeable but that the WIPP setting was hydrologically inactive. Favorable mechanical properties ensure isolation of materials placed in a salt geological setting. Key areas of the geomechanics investigations leading to the certification of WIPP are in situ experiments, laboratory tests, and shaft seal design.
An evaluation was performed which examined the aging of surface mount solder joints assembled with 91.84Sn-3.33Ag-4.83Bi solder. Defect analysis of the as-fabricated test vehicles revealed excellent solderability, good package alignment, and a minimum number of voids. Continuous DC electrical monitoring of the solder joints did not reveal opens during as many as 10,000 thermal cycles (0 C, 100 C). The solder joints exhibited no significant degradation through 2500 cycles, based upon an absence of microstructural damage and sustained shear and pull strengths of chip capacitors and J-leaded solder joints, respectively. Thermal cycles of 5000 and 10,000 resulted in some surface cracking of the solder fillets and coatings. In a few cases, deeper cracks were observed in the thinner reaches of several solder fillets. There was no deformation or cracking in the solder located in the gap between the package I/O and the circuit board pad nor in the interior of the fillets, both locations that would raise concerns of joint mechanical integrity. A drop in the chip capacitor shear strength was attributed to crack growth near the top of the fillet.
The Z Accelerator is a fast pulse power facility capable of performing high-pressure studies of the dynamic response of materials under loading conditions unachievable with other methods. A variety of advanced laser diagnostics have been implemented on the facility for shock physics experiments. These include multipoint laser velocity interferometry,line and full field velocity interferometry, time-resolved optical and uv spectroscopy, and both active and passive shock breakout.
Shock-induced depoling of the ferroelectric ceramic PZT 95/5 is utilized in a number of pulsed power devices. Several experimental and theoretical efforts are in progress in order to improve numerical simulations of these devices. In this study we have examined the shock response of normally poled PZT 95/5 under uniaxial strain conditions. On each experiment the current produced in an external circuit and the transmitted waveform at a window interface were recorded. The peak electrical field generated within the PZT sample was varied through the choice of external circuit resistance. Shock pressures were varied from 0.6 to 4.6 GPa, and peak electrical fields were varied from 0.2 to 37 kV/cm. For a 2.4 GPa shock and the lowest peak field, a nearly constant current governed simply by the remanent polarization and the shock velocity was recorded. Both decreasing the shock pressure and increasing the electrical field resulted in reduced current generation, indicating a retardation of the depoling kinetics.
A method for finding a global optimum to the on-off minimum-time control problem with limited fuel usage is presented. Each control can take on only three possible values: maximum, zero, or minimum. The simplex method for linear systems naturally yields such a solution for the re-formulation presented herein because it always produces an extreme point solution to the linear program. Numerical examples for the benchmark linear flexible system are presented.
This work is an experimental investigation of the ability of a real three-link direct-drive arm to track model-based minimum-time trajectories that have been found off-line. Sufficiently large velocity gains in the computed torque control law were not achievable with the velocity sensors described herein. This indicates the critical importance of the velocity sensing when attempting to track trajectories that push the envelope of the system's torque capabilities.