Publications

There currently exists a critical need for tools to enhance the industrial competitiveness and agility of US industries involved in deformation processing of structural alloys. In response to this need, Sandia National Laboratories has embarked upon the QuikForm Initiative. The goal of this program is the development of computer-based tools to facilitate the design of deformation processing operations. The authors are currently focusing their efforts on the definition/development of a comprehensive system for the design of sheet metal stamping operations. The overall structure of the proposed QuikForm system is presented, and the focus of their thrust in each technical area is discussed.

The authors are working to understand why predictions of degradation behaviors and rates, based on accelerated thermal aging experiments, often fail to match with aging of polymers under service conditions. A main goal of these studies is to develop more reliable lifetime prediction methodologies.

Hydrous Metal Oxides (HMOs) are chemically synthesized materials which contain a homogeneous distribution of ion exchangeable alkali cations that provide charge compensation to the metal-oxygen framework. Both the presence of these alkali cations and the resulting high cation exchange capacities (4-5 meq/g) clearly set these HMO materials apart from conventional precipitated hydrous oxides. For catalyst applications, the HMO material serves as an ion exchangeable support which facilitates the uniform incorporation of catalyst precursor species. Following catalyst precursor incorporation, an activation step is required to convert the catalyst precursor to the desired active phase. Considerable process development activities at Sandia National Laboratories related to HMO materials have resulted in bulk silica-doped hydrous titanium oxide (HTO:Si)-supported NiMo catalysts that are more active in model compound reactions than commercial NiMo catalysts. These reactions, e.g. pyrene hydrogenation, simulate direct coal liquefaction. However, extension of this process to produce NiMo/HTO:Si catalyst coatings on commercial supports is of interest for liquefaction applications since overall catalyst cost can be reduced and bulk HTO:Si mechanical limitations can be circumvented. In the present effort, NiMo/HTO:Si has been evaluated for hydrodesulfurization (HDS) and hydrodenitrogenation (HDN) of coal derived liquids. NiMo/HTO:Si catalysts have been evaluated in both bulk (unsupported) form and a supported form on commercial alumina extrudates.

Degradation in nMOS transistors from gate oxide shorts is dependent upon oxide trapping and interface state generation. Three distinct damage mechanisms were identified, including generation of: (1) electron traps in the bulk oxide by the injected holes, N{sub ox,h}, (2) electron traps in the bulk oxide by the injected electrons, N{sub ox,e}, and (3) interface states, N{sub ss}. The three damage mechanisms are incorporated into a device lifetime prediction method.

Procedures for trajectory planning and control of flexible link robots are becoming increasingly important to satisfy performance requirements of hazardous waste removal efforts. It has been shown that utilizing link flexibility in designing open loop joint commands can result in improved performance as opposed to damping vibration throughout a trajectory. The efficient use of link compliance is exploited in this work. Specifically, experimental verification of minimum time, straight line tracking using a two-link planar flexible robot is presented. A numerical optimization process, using an experimentally verified modal model, is used for obtaining minimum time joint torque and angle histories. The optimal joint states are used as commands to the proportional-derivative servo actuated joints. These commands are precompensated for the nonnegligible joint servo actuator dynamics. Using the precompensated joint commands, the optimal joint angles are tracked with such fidelity that the tip tracking error is less than 2.5 cm.

Technologies for the demilitarization and disposal of conventional munitions and energetic materials are presented. A hazard separation system has been developed to remove hazardous subcomponents before processing. Electronic component materials separation processes have been developed that provide for demilitarization as well as the efficient recycling of materials. Energetic materials demilitarization and disposal using plasma arc and molten metal technologies are currently being investigated. These regulatory compliant technologies will allow the recycling of materials and will also provide a waste form suitable for final disposal.

A new dimensionless parameter model for continuous wave laser welding that relates the size of the weld to the energy absorbed by the part is described. The model has been experimentally validated previously through calorimetric determinations of the net heat input and metallographic measurements of the weld size. It will be shown that both the melting efficiency and energy transfer efficiency for LBW are quite variable and need to be considered when selecting processing conditions. Specific applications will be detailed in order to observe the simplicity and value of the model in laser weld process development. It will be shown that by using certain dimensionless parameters one can determine the energy transfer efficiency and thereby correctly select processing conditions that more fully utilize the available laser output power. In applications where minimizing heat input to the surrounding weldment is paramount, the dimensionless parameters can be used to select conditions that maximize melting efficiency.

Artificial neural networks (ANNs) have been shown capable of simulating the behavior of complex, nonlinear, systems, including structural systems. Under certain circumstances, it is desirable to simulate structures that are analyzed with the finite element method. For example, when we perform a probabilistic analysis with the Monte Carlo method, we usually perform numerous (hundreds or thousands of) repetitions of a response simulation with different input and system parameters to estimate the chance of specific response behaviors. In such applications, efficiency in computation of response is critical, and response simulation with ANNs can be valuable. However, finite element analyses of complex systems involve the use of models with tens or hundreds of thousands of degrees of freedom, and ANNs are practically limited to simulations that involve far fewer variables. This paper develops a technique for reducing the amount of information required to characterize the response of a general structure. We show how the reduced information can be used to train a recurrent ANN. Then the trained ANN can be used to simulate the reduced behavior of the original system, and the reduction transformation can be inverted to provide a simulation of the original system. A numerical example is presented.

Photoluminescence measurements on ordered InGaP{sub 2} were studied as a function of temperature, laser power density, and magnetic field. The temperature varied between 1.4 and 300 K, the laser power densities ranged from 10 nW/cm{sup 2} to 20 W/cm{sup 2}, and the maximum magnetic field was 13.6 T. The data show both excitonic and band-to-band behavior, depending upon the incident laser power density. A consistent interpretation of all data leads to a type-II valence-band offset between the ordered domains.

Conduction and valence-band dispersion curves determined by magnetoluminescence are presented for n-type InGaAs/GaAs strained-single-quantum well structures. The magnetic field range was 0 to 30 tesla, and the temperature varied between 4.2 and 77.4 K.

Thickness shear mode (TSM) quartz resonators operating in a new {open_quotes}Lever oscillator{close_quotes} circuit are used as monitors for critical automotive fluids. These monitors respond to the density and viscosity of liquids contacting the quartz surface. Sensors have been developed for determining the viscosity characteristics of engine lubricating oil, the state-of-charge of lead-acid storage batteries, and the concentration variations in engine coolant.

The goal of this project is to gain an understanding of the fundamental mechanisms and processes occurring in low pressure, partially ionized plasmas and their interactions with materials. Emphasis is placed on: understanding the basic atomic and molecular physics that is occurring within the plasma bulk and sheath, understanding the relation of the collective plasma dynamics to the internal atomic processes, developing the ability to perform computer simulations of the plasmas as to both Collective dynamics and inclusion of atomic properties, and analyzing the response of the materials to the plasma and how the plasma might be tailored to obtain a given effect at the material surface.

Severe reactor accident scenarios involving air ingression into the reactor coolant system are described. Evidence from modem reactor accident analyses and from the accident at Three Mile Island show residual fuel will be present in the core region when air ingression is possible. This residual fuel can interact with the air. Exploratory calculations with the MELCOR code of station blackout accidents during shutdown conditions and during operations are used to examine clad oxidation by air and ruthenium release from fuel in air. Extensive ruthenium release is predicted when air ingression rates exceed about 10 moles/s. Past studies of air interactions with irradiated reactor fuel are reviewed. Effects air ingression may have on fission product release, transport, deposition and revaporization are discussed. Perhaps the most important effects of air ingression are expected to be enhanced release of ruthenium from the fuel and the formation of copious amounts of aerosol from uranium oxide vapors. Revaporization of iodine and tellurium retained in the reactor coolant system might be expected.

The authors report major deviations in the electron effective mass m* near the partial energy gap, or minigap, formed in strongly coupled double quantum wells (QWs) by an anticrossing of the two QW dispersion curves. The anticrossing and minigap are induced by an in-plane magnetic field B{sub {parallel}} and give rise to large distortions in the Fermi surface and density of states, including a Van Hove singularity. Sweeping B{sub {parallel}} moves the minigap through the Fermi level, with the upper and lower gap edges producing a sharp maximum and minimum in the low-temperature in-plane conductance, in agreement with theoretical calculations. The temperature dependence of Shubnikov-de Haas (SdH) oscillations appearing in a tilted magnetic field yield a decreased m* {le} 1/3 m*{sub GaAs} near the upper gap edge, and indicate an increase in m* near the lower gap edge.

The PP code is a graphics post-processor and plotting program for EQ6, a popular reaction-path code. PP runs on personal computers, allocates memory dynamically, and can handle very large reaction path runs. Plots of simple variable groups, such as fluid and solid phase composition, can be obtained with as few as two keystrokes. Navigation through the list of reaction path variables is simple and efficient. Graphics files can be exported for inclusion in word processing documents and spreadsheets, and experimental data may be imported and superposed on the reaction path runs. The EQ6 thermodynamic database can be searched from within PP, to simplify interpretation of complex plots.

The Global Verification and Location System (GVLS) is a satellite based communication package proposed for the Global Positioning System (GPS) Block IIR satellites. This system provides the capability to relay bursts of information from small, low power mobile transmitters to command and control facilities. Communication paths through multiple GPS satellites within the field of view allow location of the transmitter using time difference of arrival (TDOA) techniques. Alternately, the transmitter can transmit its own location if known by various other means. Intended applications include determination of the status and location of high-valued assets such as shipments of proliferation-sensitive nuclear materials and treaty-limited items or downed air crews and special operations forces in need of extraction from hostile territory. GVLS provides an enabling technology which can be applied to weapon impact location. The remote transmitter is small and light enough to be integrated into a weapon delivery vehicle, such as a cruise missile, and requires power only during the last second of flight. The antenna is a conformal patch design, therefore minimizing aerodynamic considerations. Precise impact locations are determined by the GVLS system and can be communicated to responsible commands in near real time allowing rapid bomb damage assessment and retargeting without the typical delays of overhead reconnaissance. Since burst data communication is used, weapon status immediately prior to impact can be transmitted providing knowledge of proper arming sequence and other pertinent information. If desired, periodic bursts can be transmitted while in flight, enabling in-course tracking of the weapon. If fully deployed, the GVLS system would consist of communication relays on 24 GPS satellites, five ground stations deployed worldwide, and portable base stations for authorized users to receive and display locations and contents of their transmissions.

Sandia National Laboratories has one of the largest integrated robotics laboratories in the United States. Projects include research, development, and application of one-of-a-kind systems, primarily for the Department of Energy (DOE) complex. This work has been underway for more than 10 years. It began with on-site activities that required remote operation, such as reactor and nuclear waste handling. Special purpose robot systems were developed using existing commercial manipulators and fixtures and programs designed in-house. These systems were used in applications such as servicing the Sandia pulsed reactor and inspecting remote roof bolts in an underground radioactive waste disposal facility. In the beginning, robotics was a small effort, but with increasing attention to the use of robots for hazardous operations, efforts now involve a staff of more than 100 people working in a broad robotics research, development, and applications program that has access to more than 30 robotics systems.

For future planetary science missions, the authors are developing a series of microinstruments using the techniques of silicon-based micromachining. Conventional instruments such as chemical sensors, charged particle analyzers and mass spectrometers are reduced in size and effective volume to the dimension of cubic centimeters, while maintaining or enhancing performance. Using wafer/wafer bonding techniques, selective chemical etching, thin Film growth, and high resolution lithography, complex three dimensional structures can be assembled. This paper discusses the design, implementation and performance of two new instruments: The Micromachined Bessel Box Auger Electron Spectrometer, and the Mars Soil Chemistry Experiment (MOx).

The US Department of Energy (DOE) is responsible for disposing of a variety of radioactive and mixed wastes, some of which are considered special-case waste because they do not currently have a clear disposal option. The DOE`s Nevada Field Office contracted with Sandia National Laboratories to investigate the possibility of disposing of some of this special-case waste at the Nevada Test Site (NTS). As part of this investigation, a review of a near-surface and subsurface disposal options that was performed to develop alternative disposal configurations for special-case waste disposal at the NTS. The criteria for the review included (1) configurations appropriate for disposal at the NTS; (2) configurations for disposal of waste at least 100 ft below the ground surface; (3) configurations for which equipment and technology currently exist; and (4) configurations that meet the special requirements imposed by the nature of special-case waste. Four options for subsurface disposal of special-case waste are proposed: mined consolidated rock, mined alluvium, deep pits or trenches, and deep boreholes. Six different methods for near-surface disposal are also presented: earth-covered tumuli, above-grade concrete structures, trenches, below-grade concrete structures, shallow boreholes, and hydrofracture. Greater confinement disposal (GCD) in boreholes at least 100 ft deep, similar to that currently practiced at the GCD facility at the Area 5 Radioactive Waste Management Site at the NTS, was retained as the option that met the criteria for the review. Four borehole disposal configurations are proposed with engineered barriers that range from the native alluvium to a combination of gravel and concrete. The configurations identified will be used for system analysis that will be performed to determine the disposal configurations and wastes that may be suitable candidates for disposal of special-case wastes at the NTS.

Over the last 20 years, a family of lowpass filters has been developed to eliminate electromechanical interference from power and signal lines in weapon systems. Since its inception, Sprague Electric in North Adams, Massachusetts, has produced this family of components on a line dedicated solely to these devices. Although at least seven other companies produce similar filters, suppliers are unwilling to build small quantities of components in a manner that is incompatible with their standard methods and equipment. The ability to fabricate products in small quantities on an occasional basis is an important factor in component development, and compatibility with commercially available devices enhances that ability. The Mil-F-28861/5 specifications, developed by the Defense Electronic Parts Supply Center, describe filters similar to those of the MC family. This report documents the evaluation of Mil-F-28861/5 filters acquired from the eight suppliers and serves as a basis for further development of specifications and suppliers.

The Environmental Restoration Program at Sandia National Laboratories, New Mexico (SNL/NM) is tasked with performing assessments and cleanup of waste sites that belong to SNL. SNL`s waste sites are divided into several activities. Septic Tanks and Drainfields (STD) is an activity that includes 23 different sites at SNL/NM. All these sites may have released hazardous wastes into the soil from drains or sewers of buildings. The STD sites must be assessed and, if necessary, remediated according to the Resource Conservation and Recovery Act (RCRA) Corrective Action process. A modeling study has been completed to help prioritize the sites for future field investigation based on the risk that each site may pose to human health and the environment. Two of the influences on the risk to human health and environment are addressed in this study--the fluid disposal volume and groundwater depth. These two parameters, as well as several others, were used as input into a computer model to calculate groundwater travel time to the water table. The computer model was based on Darcy`s Law and a simple mass balance. To account for uncertainty in the input parameters, a Monte Carlo approach was used to determine the travel times; 1,000 realizations were completed to determine the travel time for each site. The range assigned to each of the input parameters was sampled according to an assigned statistical distribution using the Latin Hypercube Method to arrive at input for the calculations. The groundwater travel times resulting from these calculations were used to rank the sites for future field investigation.

Minimum detectable irradiance levels for a diffraction grating based laser sensor were calculated to be governed by clutter noise resulting from reflected earth albedo. Features on the earth surface caused pseudo-imaging effects on the sensor`s detector arras that resulted in the limiting noise in the detection domain. It was theorized that a custom aperture transmission function existed that would optimize the detection of laser sources against this clutter background. Amplitude and phase aperture functions were investigated. Compared to the diffraction grating technique, a classical Young`s double-slit aperture technique was investigated as a possible optimized solution but was not shown to produce a system that had better clutter-noise limited minimum detectable irradiance. Even though the double-slit concept was not found to have a detection advantage over the slit-grating concept, one interesting concept grew out of the double-slit design that deserved mention in this report, namely the Barker-coded double-slit. This diffractive aperture design possessed properties that significantly improved the wavelength accuracy of the double-slit design. While a concept was not found to beat the slit-grating concept, the methodology used for the analysis and optimization is an example of the application of optoelectronic system-level linear analysis. The techniques outlined here can be used as a template for analysis of a wide range of optoelectronic systems where the entire system, both optical and electronic, contribute to the detection of complex spatial and temporal signals.

This revision updates Sandia`s working standard for testing optical fiber and unshielded twisted pair cables included in the Lab-wide telecommunications cabling infrastructure. The purpose of these standard testing procedures is to deliver to all Sandians a reliable, low-maintenance, state-of-the-art, ubiquitous telecommunications cabling infrastructure capable of satisfying all current and future telecommunication needs.

The definitions of source terms to reactor containments and source terms to the environment are discussed. A comparison is made between the TID-14844 example source term and the alternative source term described in NUREG-1465. Comparisons of these source terms to the containments and those used in France, Germany, Japan, Sweden, and the United Kingdom are made. Source terms to the environment calculated in NUREG-1500 and WASH-1400 are discussed. Again, these source terms are compared to those now being used in France, Germany, Japan, Sweden, and the United Kingdom. It is concluded that source terms to the containment suggested in NUREG-1465 are not greatly more conservative than those used in other countries. Technical bases for the source terms are similar. The regulatory use of the current understanding of radionuclide behavior varies among countries.

Bellows are an integral part of the containment pressure boundary in nuclear power plants. They are used at piping penetrations to allow relative movement between piping and the containment wall, while minimizing the load imposed on the piping and wall. Piping bellows are primarily used in steel containments; however, they have received limited use in some concrete (reinforced and prestressed) containments. In a severe accident they may be subjected to pressure and temperature conditions that exceed the design values, along with a combination of axial and lateral deflections. A test program to determine the leak-tight capacity of containment penetration bellows is being conducted under the sponsorship of the US Nuclear Regulatory Commission at Sandia National Laboratories. Several different bellows geometries, representative of actual containment bellows, have been subjected to extreme deflections along with pressure and temperature loads. The bellows geometries and loading conditions are described along with the testing apparatus and procedures. A total of thirteen bellows have been tested, all in the `like-new` condition. (Additional tests are planned of bellows that have been subjected to corrosion.) The tests showed that bellows are capable of withstanding relatively large deformations, up to, or near, the point of full compression or elongation, before developing leakage. The test data is presented and discussed.