Researchers around the world have demonstrated the effectiveness of titanium dioxide-based photocatalysis for decontaminating water containing hazardous organics and heavy metals. A great advantage of this process is that the organic is completely destroyed, leaving behind only water, carbon dioxide and dilute mineral acids. Also, the process has potential for doing two decontamination jobs at once: oxidizing organics while reducing toxic metals. As part of a program sponsored by the DOE, Sandia National Laboratories is carrying out large-scale tests to study the solar destruction of organics at realistic processing rates in addition to laboratory work aimed at determining the applicability of solar detoxification to the removal of heavy metals. In this paper, we present up-to-date results from Sandia's effort. The large-scale tests illustrate the effectiveness of solar detoxification for a variety of organics and compare measured reaction rates against published values of the rate constants for attack by aqueous hydroxyl radicals. This comparison highlights the importance of hydroxyl radical chemistry in solar detoxification processes. It is concluded that solar detoxification is only feasible for easily destroyed compounds like TCE, and PCE. The chlorinated methanes and ethanes are much more difficult to destroy and require very large solar collectors. In the second part of the paper, laboratory data are presented for a variety of different metals, including Ag, Cd, Cu, Hg, Ni, and Pt. The concentration of dissolved oxygen is one of the variables in the study. It is shown that the presence of dissolved metals can have a profound effect on organic oxidation rate, and that oxygen is not necessarily required for oxidation to occur. It is concluded that solar detoxification would be useful for removing mercury and silver but not for copper, nickel nor cadmium. 38 refs., 7 figs., 2 tabs.
Titanium dioxide (TiO{sub 2}) is a photocatalyst for solar detoxification of water containing organic contaminants such as solvents, PCB's, dioxins, pesticides, and dyes. Unfortunately, the ultraviolet (UV) energy used by TiO{sub 2} ({lambda}<400 nm) only comprises about 4% of the solar spectrum. One way of enhancing the efficiency of solar detoxification technologies is to utilize a larger portion of the solar spectrum to initiate the Tio{sub 2}- catalyzed detoxification chemistry. Metalloporphyrins strongly absorb visible and near infrared radiation. By utilization of a process called photosensitization, adsorption of these dyes onto TiO{sub 2} can enable a much broader portion of the solar spectrum to be used. Photosensitization relies upon the ability of the dye molecule to absorb more of the solar energy than bare TiO{sub 2} and to interact electronically with the TiO{sub 2} surface in such a way as to initiate TiO{sub 2}-based redox photochemistry using the dye-absorbed energy. 16 refs., 7 figs.
This document contains planned actions to correct the deficiencies identified in the Pre-Tiger Team Self-Assessment (PTTSA), January 1991, of Sandia National Laboratories (SNL -- Albuquerque, New Mexico; Tonopah, Nevada; and Kauai, Hawaii). The Self-Assessment was conducted by a Self-Assessment Working Group consisting of 19 department managers, with support from Environment, Safety, and Health (ES H) professionals, from October through December 1990. Findings from other past audits, dating back to 1985, were reviewed and compared with the PTTSA findings to determine if additional findings, key findings, or root causes were warranted. The resulting ES H Action Plan and individual planned actions were prepared by the ES H Action Plan Project Group with assistance from the Program owners/authors during February and March 1991. The plan was reviewed by SNL Management in April 1991. This document serves as a planning instrument for the Laboratories to aid in the scoping and sizing of activities related to ES H compliance for the coming five years. It will be modified as required to ensure a workload/funding balance and to address the findings resulting from the Tiger Team assessment at SNL, Albuquerque. The process of producing this document has served well to prepare SNL, Albuquerque, for the coming task of producing the required post-Tiger Team action plan document. 8 tabs.
The degree of oxidation of drops of aluminum metal was investigated parametrically for a range of melt diameters, relative melt-water velocities, melt temperatures, water temperatures, and ambient pressures using a combined film boiling-metal oxidation model. The model predictions of degree of oxidation were then compared to small-scale experiments involving molten drops of aluminum metal. The conclusions were, first, that for the range of melt temperatures and diameters considered, if an oxide layer forms and blankets the molten aluminum, then no significant oxidation occurs, in agreement with the results of experiments performed under quiescent, steady-state conditions. Second, comparing model results to data from single drop fragmentation experiments indicates that under the transient conditions occurring during rapid fragmentation, the oxide layer is disturbed and oxidation rates are limited primarily by the amount of steam available at the melt surface. Third, for a range of parameters, the heat gain in the melt drop from the oxidation reaction can exceed the heat loss to the surroundings, resulting in thermal runaway and ignition of the melt. This effect is observed experimentally as a threshold temperature effect, predicted to be about 1100 K for the initial single drop study, and between 1500 K and 1600 K for the single drop experiments. 7 refs., 2 tabs.
It is shown that preirradiation channel-mobility and 1/f-noise measurements can reveal a great deal about postirradiation interface- and oxide-trap charge buildup in MOS transistors. A model is developed to explain the observed correlations. 10 refs., 4 figs.
The effectiveness of hardening the SA3300 against SEU using design and design-plus-resistor approaches is presented. The full performance and SEU tolerance requirements are met using R{sub fb} {le} 160 k{Omega}. Lumped-parameter circuit simulations are used to analyze results. 10 refs., 5 figs.
The chemical synthesis of advanced ceramic and glass materials by the sol-gel process has become an area of increasing activity in the field of material science. The sol-gel process provides a means to prepare homogeneous, high purity materials with tailored chemical and physical properties. This paper surveyed the nuclear magnetic resonance (NMR) studies of silicon-based sol-gel kinetics. A review of the various models which have been used to analyze the chemical kinetics of various sol-gel systems was presented. The utility of NMR spectroscopy was demonstrated in investigating the influence that various reaction conditions have on the reaction pathways by which sol-gel derived materials are synthesized. By observing in a direct fashion the chemical pathway of the sol-gel, it is often possible to relate the final properties of the material to the formulation and reaction conditions of the sol-gel. The study of reaction kinetics by NMR is expected to play an increasingly important role in understanding sol-gel processing and material properties. 15 refs. (DP)
The durability of a carbon-carbon composite, Aerolor A05, X-point divertor dump plate to thermal fatigue was evaluated for the Joint European Torus (JET) at Sandia's Plasma Material Test Facility. Of primary interest was the effect of thermal cycling on the carbon-carbon threads of the bolted attachment scheme for the Aerolor X-point divertor. This report describes the testing performed at the Ion Beam Test System and the test and analysis results obtained in support of this effort. After completing 1000 thermal cycles, where the surface temperature of the 8 cm by 8 cm by 2.3 cm Aerolor tile reached 2200{degree}C during a 10 s, 500 W/cm{sup 2} pulse, the tile survived without any noticeable damage. Post test inspection of the carbon-carbon threads showed only minor wear and no signs of significant damage. Thermal modeling of the test article using the ABAQUS finite element code agreed very well with experimental results. The thermal creep experienced by the M-12 stainless steel bolt during ion beam testing will not be expected to occur during normal operations in JET because of the longer cycle times between the thermal events. Finite element analysis indicates that the longer cycle times at the JET will reduce the peak temperatures in the vicinity of the bolt and bolt insert below the level at which thermal creep would occur. An additional margin of safety could be obtained by using Inconel or Nimonic fasteners. Overall, the performance of the bolted divertor design to thermal fatigue was acceptable. 12 figs., 2 tabs.
An electromagnetic measurement system (EMMS) was designed and constructed to provide essential data relating to electromagnetic compatibility (EMC) of modern weapons carried on military aircraft. This system measures the equivalent plane wave electric and magnetic fields impinging on a weapon's exterior surface arising from electromagnetic radiators on board host or nearby aircraft. To relate practical sensor responses to specified equivalent plane wave EMC field levels, a modern weapon shape was used as the primary sensor element which responds with a simple dipole antenna response at the lower frequencies and is instrumented with local skin current sensors. At higher frequencies, the locally induced currents can be related to the incident fields by simple scattering theory. Finally, an error analysis that catalogs all measurement path elements was performed to provide an error bound on the equivalent free electric field measurements reported by the EMMS. 6 refs., 9 figs.
Micromachining is a rapidly growing field which allows for the fabrication of extremely small sensors and actuators using many of the techniques common to microelectronics. Two methods are commonly used: bulk micromachining, which involves the sculpting of single crystal silicon, and surface micromachining, which uses etched thin films that have been deposited on the substrate. Sensors are the primary commercial application, but microactuators are being actively researched at several laboratories and universities. Sandia National Laboratories is pursuing applications of both bulk and surface micromachining for silicon microsensors, microactuators, and high-performance, silicon packages for microelectronics. 3 figs.
This is an extension of two previous analytical studies to investigate a technique for generating high frequency, high amplitude vibration environments. These environments are created using a device attached to a common vibration exciter that permits multiple metal on metal impacts driving a test surface. These analytical studies predicted that test environments with an energy content exceeding 10 kHz could be achieved using sinusoidal and random shaker excitations. The analysis predicted that chaotic vibrations yielding random like test environments could be generated from sinusoidal inputs. In this study, a much simplified version of the proposed system was fabricated and tested in the laboratory. Experimental measurements demonstrate that even this simplified system, utilizing a single impacting object, can generate environments on the test surface with significant frequency content in excess of 40 kHz. Results for sinusoidal shaker inputs tuned to create chaotic impact response are shown along with the responses due to random vibration shaker inputs. The experiments and results are discussed. 4 refs., 5 figs.
Sandia National Laboratories has utilized pool fires for over thirty years to subject military components, weapon mockups and hazardous material shipping containers to postulated transportation accident environments. Most of the tests have been performed in either open pools or wind shielded facilities with little control of visible smoke emissions. Because of the increased sensitivity of environmental issues and because wind generates the biggest uncontrollable effect on the thermal environment in open pool fires, enclosed test facilities with reduced visible emissions have been developed. The facilities are basically water cooled enclosures fitted with controlled air supply systems and high temperature afterburners. The purpose of this paper is to present our experience with both open and enclosed fires. In the first section, a review of the fire test facilities is given. A following section presents a mathematical model behind our approach to characterizing the fire environment. In the last section, data from open and closed fires are compared.
Research programs from Sandia Laboratory in Materials Science are briefly presented. Significant accomplishments include: preparation of Tl superconductors under equilibrium conditions, development of force-feedback sensor for interfacial force microscope, predictive model of hydrogen interactions in silicon dioxide on silicon, layer-by-layer sputtering of Si (001), oscillatory As{sub 4} surface reaction rates during molecular beam epitaxy of AlAs, GaAs and InAs, the effects of interfacial strain on the band offsets of lattice matched III-V semiconductor, a new mechanism for surface diffusion, solid solution effects in Tl-containing superconductors, record high superconducting transitions for organic materials, atomic vibrations in boron carbides and a method for studying radical/surface reactions in chemical vapor deposition (CVD).
Recent government actions to eliminate Chlorofluorocarbons (CFCs) and Chlorinated Hydrocarbons (CHCs) from the industrial environment require the evaluation of new cleaning solvents and processes. High reliability printed wiring board (PWB) assemblies require cleaning to remove process materials which could lead to corrosion or degradation of the electrical performance of the boards. In the past, CFCs have been used extensively for PWB cleaning purposes. Concerns about CFC emissions and their effect on ozone depletion in the atmosphere, greater demands on cleaning systems, and the availability of alternative cleaning methods are requiring manufacturers of electronic assemblies to reconsider the choice of cleaning methods. We will review some of the presently available cleaning solvents and discuss the results of our work using a terpene-based cleaner. 5 refs., 4 figs.
The Recirculating Linear Accelerator (RLA) is returning to operation with a new electron beam injector and a modified accelerating cavity. Upon completion of our experimental program the RLA will capture the injected beam on an IFR guiding plasma channel in either a spiral or a closed racetrack drift tube. The relativistic beam will be efficiently recirculated for up to four passes through two or more accelerating cavities, in phase with the ringing cavity voltage waveforms, and thereby increased in energy to 10 MeV before being extracted. The inductively isolated four-stage injector was designed to produce beam parameters of 4 MeV, 10--20 kA, and 40--55 ns FWHM. The three-line radial cavity is being modified to improve the 1-MV accelerating voltage pulse shape while an advanced cavity design study is in progress. The actual versus predicted pulsed-power performance of the RLA injector and cavity and the associated driving hardware will be discussed in this paper.
Last year at the HP82000 Users Group Meeting, Sandia National Laboratories gave a presentation on I{sub DDQ} testing. This year, we will present some advances on this testing including DUT board fixturing, external DC PMU measurement, and automatic IDD-All circuit calibration. This paper is geared more toward implementation than theory, with results presented from Sandia tests. After a brief summary I{sub DDQ} theory and testing concepts, we will describe how the break (hold state) vector and data formatting present a test vector generation concern for the HP82000. We than discuss fixturing of the DUT board for both types of I{sub DDQ} measurement, and how the continuity test and test vector generation must be taken into account. Results of a test including continuity, IDD-All and I{sub DDQ} Value measurements will be shown. Next, measurement of low current using an external PMU is discussed, including noise considerations, implementation and some test results showing nA-range measurements. We then present a method for automatic calibration of the IDD-All analog comparator circuit using RM BASIC on the HP82000, with implementation and measurement results. Finally, future directions for research in this area will be explored. 14 refs., 16 figs.
CEPXS/ONELD is the only discrete ordinates code capable of modelling the fully-coupled electron-photon cascade at high energies. Quantities that are related to the particle flux such as dose and charge deposition can readily be obtained. This deterministic code is much faster than comparable Monte Carlo codes. The unique adjoint transport capability of CEPXS/ONELD also enables response functions to be readily calculated. Version 2.0 of the CEPXS/ONELD code package has been designed to allow users who are not expert in discrete ordinates methods to fully exploit the code's capabilities. 14 refs., 15 figs.
With the current trends towards miniaturization, high performance, high quality and cost competiveness, the electrodeposition process has become an important manufacturing technology in many new microelectronic applications. Gold electrodeposition plays an increasing role in processes that require this noble metal. Added to these trends is the continuing and increasing emphasis on manufacturing processes which are less damaging to the environment and potentially less hazardous to the operator and personnel in the vicinity of the operation. The present standard gold plating solutions are based on cyanide salts and are considered acutely hazardous solutions. The trend away from their use is gaining momentum as new non-hazardous gold plating solutions and manufacturing processes making use of them are developed. 2 refs.
A performance assessment methodology has been developed for use by the US Nuclear Regulatory Commission in evaluating license applications for low-level waste disposal facilities. This report provides detailed guidance on input and output procedures for the computer codes recommended for use in the methodology. Seven sample problems are provided for various aspects of a performance assessment analysis of a simple hypothetical conceptual model. When combined, these sample problems demonstrate how the methodology is used to produce a dose history for the site under normal conditions, and to demonstrate an analysis of an intruder scenario. 20 refs., 26 figs., 4 tabs.
Results of calculations performed with MELCOR and HECTR in support of the NUREG-1150 study are presented in this report. The analyses examined a wide range of issues. The analyses included integral calculations covering an entire accident sequence, as well as calculations that addressed specific issues that could affect several accident sequences. The results of the analyses for Grand Gulf, Peach Bottom, LaSalle, and Sequoyah are described, and the major conclusions are summarized.
Electromagnetic coupling to electronic components or subsystems is a concern in modern system design. Undesired coupling can cause interference or, in the extreme, system upset. To be able to characterize the coupling is an important step to understanding the limitations on system performance. Often the approach is taken to shield the electronic equipment inside some kind of enclosure. However, there are usually inadvertent cracks or bowing at mechanical interfaces. These gaps are apparent slot apertures. An equivalent antenna/local transmission line model for narrow slot apertures with depth including losses has been developed. It may be applied tortuous paths and hence may be used to model practical situations. This model has been previously verified by measuring the coupling through narrow slot apertures with varying width and depth. These measurements were performed for brass slots radiating into a half-space. The results were in good agreement with the model of Warne and Chen. The models, as well as the measurements showed that for very narrow slots the wall loss becomesdominant -- it has been demonstrated that the inclusion of loss is important in making realistic coupling estimates in practical configurations. This paper presents results showing the effects of varying conductivity and surface preparations for half-space coupling as well as different loadings of the narrow slot apertures. The coupling through narrow slot apertures having depth was measured for a variety of resonant cavity loadings. The loadings were chosen such that the cavity resonant frequencies were above, near and below the resonant peak of the half-space coupling curve. Measurements were made in the 2--4 GHz band with vertical polarization. 3 refs., 6 figs., 1 tab.
The solidification behavior of Custom Age 625 PLUS{reg sign} is examined using an integrated analytical approach. Like its predecessors, Alloys 625 and 718, the solidification behavior of this new alloy is dominated by the presence and segregation of Nb, which gives rise to a {gamma}/Laves terminal solidification constituent. 8 refs., 5 figs., 2 tabs.
Iterative, annual performance-assessment calculations are being performed for the Waste Isolation Pilot Plant (WIPP), a planned underground repository in southeastern New Mexico, USA for the disposal of transuranic waste. The performance-assessment calculations estimate the long-term radionuclide releases from the disposal system to the accessible environment. Because direct experimental data in some areas are presently of insufficient quantity to form the basis for the required distributions. Expert judgment was used to estimate the concentrations of specific radionuclides in a brine exiting a repository room or drift as it migrates up an intruding borehole, and also the distribution coefficients that describe the retardation of radionuclides in the overlying Culebra Dolomite. The variables representing these concentrations and coefficients have been shown by 1990 sensitivity analyses to be among the set of parameters making the greatest contribution to the uncertainty in WIPP performance-assessment predictions. Utilizing available information, the experts (one expert panel addressed concentrations and a second panel addressed retardation) developed an understanding of the problem and were formally elicited to obtain probability distributions that characterize the uncertainty in fixed, but unknown, quantities. The probability distributions developed by the experts are being incorporated into the 1991 performance-assessment calculations. 16 refs., 4 tabs.
Segmentation is a process of separating objects of interest from their background or from other objects in an image. Without a suitable segmentation scheme, it is very difficult to detect contraband in X-rays images. In this paper, a Probabilistic Relaxation Labeling (PRL) segmentation scheme is presented and compared with other segmentation methods. PRL segmentation is an interative algorithm that labels each pixel in an image by cooperative use of two information sources: the pixel probability and the degree of certainty of its probability supported by the neighboring pixels. The practical implementation and results of the PRL segmentation on X-ray baggage images are also discussed and compared with other segmentation methods. 13 refs., 12 figs.
This investigation describes how a statistically designed experiment can be useful to characterize the relationship between a fundamental material property such as the glass transition temperature, Tg, and various processing parameters, e.g. composition, cure time, and temperature. To illustrate, formulation weighing errors can have a dramatic affect on material properties such as thermal, mechanical, and electrical properties. The glass transition temperature was selected for monitoring because it represents the materials state of cure and it is relatively easy to determine. Specifically, EPON 828 systems cured with diethanolamine and Shell Z, respectively, were investigated plus a mixture of the latter that employed aluminum oxide as a filler. This investigation showed that Tg changed very little with cure temperature in the DEA system compared to Shell Z, whereas the latter system appeared to display synergistic effects contrary to the DEA system. In the filled formulation, loading level had very little effect on Tg. The significance of this study is that the relationship between Tg, the composition and processing factors can be used to help diagnose the cause of misprocessed material. 2 refs., 11 figs., 3 tabs.