An understanding of dispersal of nuclear materials from an explosive event is needed to support design studies of weapon storage and transportation. Assessing the consequences and requirements for cleanup of a fire or nonnuclear detonation of a system containing nuclear material requires knowledge of the aerosol formation process. Information about the aerosol chemical composition, the physical size and shape of the particulates, as well as the efficiency of aerosol formation ate needed to conduct meaningful assessments. This report describes laboratory tests to study aerosol from materials of interest. An electromagnetic launcher is used to heat and propel molten metallic samples under energetic high-velocity conditions. We describe the apparatus and first results from tests using uranium-molybdenum alloy samples. Contained laboratory-scale measurements are described that determine aerosol morphology, chemical composition, and aerosol formation efficiency under high-velocity conditions. Data from the launcher tests describe (1) the aerodynamic breakup process of high-velocity molten liquid into droplets, and (2) the formation of still finer aerosols by combustion of these droplets at high velocity. The measurements show efficient aerosol production in air that is dominated by the formation of fine chain-agglomerate combustion aerosol. Particle morphology information for both the chain agglomerate and the less common liquid breakup products is described. The aerodynamic breakup of the liquid sample material is described. Lognormal distributions are shown to accurately represent the data. The geometric mean diameter is related to the mass mean diameter and maximum stable droplet diameter for the distributions. 28 refs., 27 figs., 3 tabs.
Several potential incident scenarios involving the accidental release of radioactive material at five reference, nonreactor nuclear material licensees are analyzed in this report. The economic risk ($/licensee/yr) of decontamination is evaluated for each reference licensee. Although most releases and cleanup costs are minor, some less frequent incidents may result in very high cleanup costs that dominate the economic risk of decontamination of a particular licensee. The economic risk for the 5 plants ranged from a low of $14,000 per licensee per year to a high of $104,000 per licensee per year. This report is the second of two reports by Sandia National Laboratories on the economic risk of nonreactor nuclear material licensee operations. 40 refs., 21 figs., 31 tabs.
Both the US Environmental Protection Agency (EPA) and the US Nuclear Regulatory Commission (NRC) have promulgated regulations regarding the performance of geologic repositories for the disposal of high-level nuclear waste. One of the responsibilities of the US Department of Energy (DOE) is to demonstrate compliance with the appropriate regulations. The DOE will most likely use extensive numerical modeling to show compliance with the various quantitative requirements. These analyses will then be evaluated by the NRC. There are different levels of evaluation: peer review, conservative estimates,used of existing models/codes, and development of models/codes by the NRC. The intensity of the review will vary from analysis to analysis, depending on the importance of the analysis, the acceptability of the conceptual model behind the analysis and the solution technique used, and the potential for increasing confidence in the system description, should the NRC decide to develop its own models/codes. An appropriate level of review can be determined by applying these four criteria in a specific manner. 24 refs.
This report examines the computational implementation of a continuum model for jointed rock media. The jointed rock model uses strain partitioning between the elastic rock matrix and joint sets with nonlinear normal and shear responses. A specific model using a rational polynomial to describe normal joint response was first used as the basis for a computational implementation of a jointed rock model for two-dimensional problems. This particular implementation can be extended to three dimensions, but it would be a very expensive material model from a computational standpoint. The problem of trying to implement a joint model in three dimensions so that it would not be an extremely expensive computational tool has led to a study of various computational implementations of joint models for two-dimensional geometries. These studies have produced implementations of joint models that are very computationally efficient and that can handle joint models with normal joint behavior described by general relations. The implementations studied in this report make the use of jointed rock models in three dimensions much more feasible in terms of computational expense. 6 refs., 8 figs., 2 tabs.
Thermal imagers are effective tools for detecting aggressive actions and enhancing physical security in both tactical and peacetime environments. However, from an operator's perspective, these devices are rarely used on a continuous basis because of inconvenience and a requirement to have the operator be the detector'' while using the imager as a sensor. This paper describes an area sensor and assessment system designed to reduce operator fatigue and improve the effectiveness of costly thermal imagers. Several prototypes have been installed and operated at sites worldwide. The device uses a thermal imager as the primary sensor but also incorporates a laser rangefinder, automatic area precision scanning, robust scan-to-scan scene change detection, a deliberate-motion detection features. The system setup, control, and alarm assessment functions of the operator console are described. The digital processing is discussed and performance measures are given. 2 refs., 7 figs.
This report describes the development of the following new catalytic materials based on hydrous metal oxide (HMO) ion exchange materials: Na-Ti, Nb, Zr, and mixtures of hydrated silica with hydrous Ti-oxide. HMO's provide a versatile system for the preparation of heterogeneous catalysts. The preparation chemistry allows synthesis of catalysts that can be tailored to particular processes with respect to both chemical and physical properties. Bulk catalysts with surface areas over 300 m{sup 2}/g and pore volumes up to 0.4 cc/g as well as thin films of the HMO materials can be prepared on supports having a wide range of catalytically important physical properties. This report, the first of two parts, presents research performed to date regarding the preparation chemistry, and physical and chemical properties of HMO materials which may be used to develop heterogeneous catalysts for direct coal liquefaction processes. During the course of this work, new ideas for research areas relative to direct coal liquefaction were briefly explored. Two of them that merit further work, catalyst-anchored hydrogen donors and alkoxide-derived crystalline titanate compounds, are briefly described. 25 refs., 34 figs., 8 tabs.
Drillholes H-17 and H-18 were drilled at the WIPP site to assess uncertainties in site hydrologic parameters and to serve as monitoring points for planned hydrologic tests. H-17 was drilled south of H-11 and east of P-17 to evaluate the existence of a high-permeability region in the Culebra Dolomite Member that had been indicated by groundwater-flow modeling and surface geophysical surveys. H-18 was drilled north of H-2 to help reduce the uncertainties of boundaries between high and low transmissivities and fluid density that had been identified by drilling and by modeling. 1 ref., 4 figs., 6 tabs.
An extensive literature review has been conducted as part of an effort to quantify the fidelity of Sandia's lightning burn-through simulation technique. The dominant parameters affecting damage have been identified and are discussed. Two alternative techniques for qualitatively improving the Sandia simulation have been identified, but quantification of the correlation of the results of each with those of natural lightning awaits completion of further experimental work. A systematic set of laboratory experiments is proposed to assess the sensitivity of each technique to key simulation parameters. An available calibration linkage to natural lightning is the reproduction of damage spots that were created by lightning on a set of copper disks mounted on TV towers, and an attempt to do this is included in the proposed experiments. In order to reduce the uncertainties of this approach, more lightning-spot data are required, along with records of the flash currents that produced them. It is recommended that such data be acquired in conjunction with the Rocket-Triggered Lightning Program being conducted each summer at the Kennedy Space Center. 25 refs., 5 figs., 1 tab.
Harper-Slaboszewicz, V.J.; Poukey, J.W.; Stygar, W.A.; Fowler, W.E.; Peyton, B.
The inverse triax diode is a high power, low impedance electron diode which offers significant advantages over conventional electron diodes on short-pulse (<30 ns FWHM) high power x-ray simulators. Parametric calculations show that the radiation efficiency of the inverse triax is competitive with standard diodes fro mean photon energies below about 120 keV, and sometimes up to 150 keV. Particle-in-cell code simulations show the impedance behavior and flow pattern in the inverse triax with and without the presence of an anode plasma. The simulation results are used to suggest design rules for inverse triax diodes. Experimental results show good agreement with calculations of the impedance behavior and electron beam dynamics. Using inverse triax diodes, we have produced peak doses of 1.4 {times} 10{sup 11} rad(TLD)/s over 840 cm{sup 2} with a mean photon energy of 120 keV on SPEED and 3.1 {times} 10{sup 11} rad(TLD)/s over 3700 cm{sup 2} with a mean photon energy of 140 keV on Saturn. 20 refs., 16 figs.
The BES Materials Science program at Sandia Albuquerque has the central theme of Scientifically Tailored Materials. The major objective of this program is to combine Sandia's expertise and capabilities in the areas of solid state sciences, advanced atomic-level diagnostics and materials-processing science to produce new classes of tailorable materials for the US energy industry, the electronics industry and for defense needs. Current research in this program includes the physics and chemistry of ceramics, the use of energetic particles for the synthesis and study of materials, high-temperature and organic superconductors, tailored surfaces for materials applications, chemical vapor deposition sciences, strained-layer semiconductors, advanced growth techniques for improved semiconductor structures and boron-rich very high temperature semiconductors. A new start just getting underway deals with the atomic level science of interfacial adhesion. Our interdisciplinary program utilizes a broad array of sophisticated, state-of-the-art experimental capabilities provided by other programs. The major capabilities include several molecular-beam epitaxy and chemical-vapor-deposition facilities, electron- and ion-beam accelerators, laser-based diagnostics, advanced surface spectroscopies, unique combined high-pressure/low-temperature/high-magnetic-field facilities, and the soon to be added scanning tunneling and atomic force microscopies.
Calorimetry was performed on Sandia National Laboratories' Test Bed Concentrator {number sign}1 (TBC-1) during late July and early August 1989. The purpose of the tests was to determine the total power available from the concentrator and the amount of the total power that can be focused through a 22-cm aperture plate located at the nominal focal point of the dish. The 22-cm aperture corresponds to the diameter of several reflux receivers that are currently under development, fabrication and testing at Sandia. The calorimeter test will allow the efficiency of the sodium reflux receivers to be calculated. The total power (normalized to 1000 W/m{sup 2}) available from TBC-1 is 66.4 kW into the 22-cm aperture plate. Within error limits, this power level is the same with or without the aperture plate. The power levels stated are for this time (July 1989) and will probably change as the mirrors further degrade. Since the last calorimetry tests were performed, the mirror facets have degraded significantly, and the results presented here support this effect. Finally, three of the 220 facets were missing. 3 refs., 5 figs., 2 tabs.
This report describes research leading to the development of new catalytic materials based on hydrous metal oxide (HMO) ion exchangers. Present in this part, the second of two parts, are results of catalyst-related research and application of the materials to catalytic reactions for direct coal liquefaction processes. HMO materials are inorganic ion exchangers, derived from the alkoxides of Ti, Zr, Nb, or Ta, that exhibit a number of properties applicable to the preparation of catalysts. Research on the catalytic properties of HMO's has focused on the hydrous titanium oxide (HTO) system. However, exploratory coal liquefaction experiments with hydrous niobium oxides (HNO's) and hydrous zirconium oxides (HZO's) have demonstrated that these HMO's also exhibit potential as coal liquefaction catalysts. Studies performed during the course of this research include (1) preliminary coal liquefaction and hydrotreating tests, (2) tests of hydrogenation, hydrodesulfurization, hydrodeoxygenation and hydrodenitrogenation activity using model compounds, (3) development of catalyst pretreatment and activation procedures, (4) modification of HTO supports with silicon, (5) preparation and testing of thin film HTO catalysts, (6) synthesis, characterization and evaluation of base and noble metal catalyst deactivation tests, and (9) exploratory tests of applications other than direct liquefaction. The versatility of the HTO system for synthesis of catalysts allows great potential for further improvements in activity and selectivity as well as tailoring of catalysts for specific processes. Research is continuing in these areas. 54 refs., 63 figs., 25 tabs.
Drillholes H-14 and H-15 were drilled to investigate data gaps in the hydrologic hole distribution at the WIPP site. In addition to the information gained on the Culebra Dolomite Member, the holes yielded hydraulic and/or stratigraphic information on the Forty-niner, Magenta Dolomite, and Tamarisk Members of the Rustler Formation in an era where no such information was available. Hydraulic tests were also conducted on the lower part of the Dewey Lake Redbeds in H-14. A suite of geophysical logs was run on the drillholes and was used to identify different lithologies and aided in the interpretation of the hydraulic tests. 3 refs., 4 figs., 6 tabs.
This report presents a method of running batch jobs from menu-driven interactive EQUEL programs. EQUEL is the embedded query language of INGRES, a popular database management system used widely at Sandia. The method is framed in the VAX/VMS operating system environment.
For more than 10 years, the US Department of Energy's Solar Thermal Program has pioneered the development of heliostats, mirrors that track the sun, for solar central-receiver power plants. The field of heliostats is the single most expensive part of such plants, so their cost must be as low as possible for the technology to be commercially successful. Recent efforts have focused on the development of heliostats that use stretched-membrane reflectors in place of the more familiar glass mirrors. In such heliostats, metal foils are stretched over both sides of a large-diameter metal ring. The reflective surface is a silvered-polymer film glued to the front membrane. A slight vacuum in the space between the two membranes is actively controlled to provide a concave, focused contour to the mirror, and in an emergency this space can be rapidly pressurized to defocus it. Because of their simplicity and lighter weight, stretched- membrane heliostats have the potential to cost significantly less than current glass-mirror designs. The first 50-m{sup 2} mirror modules, built under contract to Sandia in 1986, demonstrated that membrane heliostats could perform at least as well as heliostats using glass mirrors. Insights gained from Sandia's testing and evaluation of the first-generation units were incorporated into the designs of two improved 50-m{sup 2} mirror modules. The results of Sandia's evaluation show significant improvement in optical performance over the first-generation designs, especially in windy conditions. 22 refs., 29 figs.
This report describes the application of word processing, graphics and data base software to the task necessary for the exclusion of Building 823 from the secure technical area at Sandia National Laboratories. In particular, this report focuses on the development of the building floor plans layouts and the space/personnel data base which were used by management to plan and coordinate the project. Once the project is complete, these information systems will continue to be maintained by other personnel for administrative purposes. The software developed has potential applicability to other facilities where administrative monitoring or space assessment is required. 6 figs.
Personnel from Stockpile Evaluation Program Division I, 7261, have been testing Joint Test Assemblies (JTAs) at Meppen Range, Federal Republic of Germany (FRG) since 1984. JTA trajectories were obtained from cinetheodolite film. The MPS-36 radar at Meppen Range is required to track the aircraft before bomb release to verify the release parameters for range safety and for the bomb trajectory after release. This is a difficult task because of the low-level approach of the aircraft. Division 7261 personnel asked Tonopah Test Range Department 7170 to assist in solving radar tracking problems. We recommended a new closed-circuit television system with a zoom lens and a force-operated, two-axis joystick. This system provides the operator a means of overriding the automode of the radar and manually positioning the radar antenna in azimuth (AZ) and elevation (EL). The joystick operator keeps the target (aircraft or bomb) centered in the TV picture by applying the correct pressure to the joystick. At the same time, the radar console operator maintains automatic range tracking by assisting the range gate through ground clutter using the control level of the range gate, as a rate-aid control in automatic mode. During the period May 8-17, 1989, the visual tracking equipment was installed in the Meppen radar. On May 16, 1989 a bomb dummy unit, loft maneuver was tracked successfully. The video, with time of day, was recorded for posttest, quick-look data. In the ten years of planned testing, a twenty-fold cost savings would be achieved with incorporation of the visual tracking capability to the MPS-36 radar, rather than providing radar beacons on each JTA. 8 figs.
Sandia National Laboratories, as part of the Containment Integrity Programs under the sponsorship of the Nuclear Regulatory Commission (NRC), has developed analytical techniques for predicting the performance of light water reactor steel containment buildings subject to loads beyond the design basis. The analytical techniques are based on experience with large-scale steel containment model tests that provided important insights and experimental validation of the analytical methods. As a means of demonstrating these analytical techniques, the NRC asked Sandia to conduct a structural evaluation of an actual steel containment building. The objective of the analysis was to determine the actual pressure capacity and the mode, location, and size of failure, where a functional definition of failure is used. The purpose of this report is to document the calculations performed to determine the pressure limits for the shell- rupture mode of failure. General failure of the containment shell is predicted by application of a failure criterion to the results from finite element structural analyses. The failure criterion relates the calculated values of strain in the containment plates, due to internal-pressurization loading, to the ultimate strain limit of the steel. Included in the failure criterion are adjustments for factors inherent in finite element analysis, such as level of detail and element size of the finite element model and variations in material property data. Separate finite element models were used to evaluate the overall free-field behavior of the structure and the localized behavior at a specific penetration location. 18 refs., 68 figs., 10 tabs.
In an experiment conducted at Sandia National Laboratories, 1:6-scale model of a reinforced concrete light water reactor containment building was pressurized with nitrogen gas to more than three times its design pressure. The pressurization produced one large tear and several smaller tears in the steel liner plate that functioned as the primary pneumatic seal for the structure. The data collected from the overpressurization test have been used to evaluate and further refine methods of structural analysis that can be used to predict the performance of containment buildings under conditions produced by a severe accident. This report describes posttest finite element analyses of the 1:6-scale model tests and compares pretest predictions of the structural response to the experimental results. Strain and displacements calculated in axisymmetric finite element analyses of the 1:6-scale model are compared to strains and displacement measured in the experiment. Detailed analyses of the liner plate are also described in the report. The region of the liner surrounding the large tear was analyzed using two different two-dimensional finite elements model. The results from these analyzed indicate that the primary mechanisms that initiated the tear can be captured in a two- dimensional finite element model. Furthermore, the analyses show that studs used to anchor the liner to the concrete wall, played an important role in initiating the liner tear. Three-dimensional finite element analyses of liner plates loaded by studs are also presented. Results from the three-dimensional analyses are compared to results from two-dimensional analyses of the same problems. 12 refs., 56 figs., 1 tab.
The Yucca Mountain Project (YMP) is examining the feasibility of siting a repository for high-level nuclear waste at Yucca Mountain, on and adjacent to the Nevada Test Site (NTS). The proposed repository will be excavated in the Topopah Spring Member, which is a moderately fractured, unsaturated, welded tuff. Excavation stability will be required during construction, waste emplacement, retrieval (if required), and closure to ensure worker safety. The subsurface excavations will be subject to stress changes resulting from thermal expansion of the rock mass and seismic events associated with regional tectonic activity and underground nuclear explosions (UNEs). Analyses of drift stability are required to assess the acceptable waste emplacement density, to design the drift shapes and ground support systems, and to establish schedules and cost of construction. This paper outlines the proposed methodology to assess drift stability and then focuses on an example of its application to the YMP repository drifts based on preliminary site data. Because site characterization activities have not begun, the database currently lacks the extensive site-specific field and laboratory data needed to form conclusions as to the final ground support requirements. This drift design methodology will be applied and refined as more site-specific data are generated and as analytical techniques and methodologies are verified during the site characterization process.
This Test Plan describes laboratory and modeling studies of: the chemistry of brines that could enter Waste Isolation Pilot Plant (WIPP) disposal rooms; the effects of anoxic corrosion of metals in steel containers and the waste on the gas and H{sub 2}O budgets of the repository; the effects of microbial activity, especially microbial degradation of cellulosics in the waste, on the gas and H{sub 2}O budgets of the repository, the Eh and pH of any brine present, and the chemical behavior of radionuclides; the effects of radiolysis on the gas and H{sub 2}O budgets of the repository; the efficacy of backfill additives proposed to remove microbially produced CO{sub 2} or prevent the formation of H{sub 2} from anoxic corrosion, and their effects on repository chemistry; the chemical behavior of Pu, Am, Th, and U in WIPP brines; additional development of the EQ3/6 geochemical software package for use in predicting the behavior of silicates and radionuclides in brines. This Test Plan describes studies of the chemical behavior of the repository as currently designed, and the chemical behavior of radionuclides under these conditions. Addenda will discuss additional studies relevant to design modifications, especially reprocessed waste, and chemically hazardous waste constituents. 165 refs., 7 tabs.
Generally multicomponent mixtures can exhibit a rich collection of phenomena. Thus it is to be expected that they will be described by complicated theories. In this paper we describe a relatively simple theory that is still theoretically correct, and discuss some of the phenomena that it exhibits. 12 refs.
The author describes a waveform-recorder evaluation system which is controlled by a Microvax II with instrumentation control through the IEEE-488 bus. Evaluation procedures are described with attention to the 'pathological cases' that can lead to significant misestimates of a digitizer's performance. The aim of these evaluation procedures is consistency with the new Trial Waveform Digitizer Standard generated by the Waveform Measurements and Analysis Committee appointed by the Instrumentation and Measurement Society of the IEEE. Methods are discussed for measuring the effective-bits performance of a waveform digitizer and determining differential nonlinearity.
Pace, C.; Doiron, T.; Stieren, D.; Borchardt, B.; Veale, R.; National Inst Of Standards And Technology, Gaithersburg (Usa)
The Primary Standards Laboratory at Sandia National Laboratories (SNL) and the Precision Engineering Division at the National Institute of Standards and Technology (NIST) are in the process of implementing software error correction on two nearly identical high-accuracy coordinate measuring machines (CMMs). Both machines are Moore Special Tool Company M-48 CMMs which are fitted with laser positioning transducers. Although both machines were manufactured to high tolerance levels, the overall volumetric accuracy was insufficient for calibrating standards to the levels both laboratories require. The error mapping procedure was developed at NIST in the mid 1970's on an earlier but similar model. The error mapping procedure was originally very complicated and did not make any assumptions about the rigidness of the machine as it moved, each of the possible error motions was measured at each point of the error map independently. A simpler mapping procedure was developed during the early 1980's which assumed rigid body motion of the machine. This method has been used to calibrate lower accuracy machines with a high degree of success and similar software correction schemes have been implemented by many CMM manufacturers. The rigid body model has not yet been used on highly repeatable CMMs such as the M48. In this report we present early mapping data for the two M48 CMMs. The SNL CMM was manufactured in 1985 and has been in service for approximately four years, whereas the NIST CMM was delivered in early 1989. 4 refs., 5 figs.
Merlin is a memory based, interconnection system designed to provide very high-performance capability in a disturbed multicomputer environment. By using dynamically mapped reflective memory operations, the system creates a virtual memory environment which permits users to utilize both local and shared memory techniques. This mapped virtual memory approach permits selected information to be shared at high speeds and with relatively low latency. There is no software involvement in the actual sharing of information and the system automatically overlaps computation and communication, to the extent possible, on a word-by-word basis. Memory-to-Memory mapping allows Merlin to provide a uniform programming environment which is independent of interconnection topology, processing elements, and languages. 14 refs., 4 figs.
In the most transmissive parts of the Culebra Dolomite, fluid flow is controlled by fractures. Gypsum (CaSO{sub 4} 2H{sub 2}O) and corrensite (a mixed chlorite/smectite) are the most abundant fracture-fill minerals. Radionuclide/clay interactions may be the dominant mechanism for radionuclide retardation. For this reason, the focus of this study is to examine the extent of the sorption of uranium and plutonium onto clays within the Culebra matrix and fractures. This paper describes several coordinated activities which will evaluate the potential retardation of radionuclide migration by sorption onto clays within the Culebras. These include characterization of the compositions of clays and groundwaters along the flow path; studies of the surface properties of simple reference clays and Culebra clays in dilute solutions and saline mixed electrolytes; development of a database of intrinsic equilibrium constants and specific-interaction parameters for calculations of the aqueous speciation of uranium and plutonium in Na-Cl-Ca-SO{sub 4}-CO{sub 3}-EDTA solutions which range in ionic strength from 0.1--4.0 molal; and measurement of surface complexation constants for uranium and plutonium in simple and mixed electrolyte solutions containing clays. 2 refs., 2 figs.
In component reliability assessment programs, three major sources of data are available for reliability assessment: a development program, production data, and field test data. In practice, reliability assessments are required at the end of each stages, and a common method of assessment is to simply combine the test data and provide a pooled estimate. The method suggested in this paper is Bayesian in that the uncertainty about the unreliability is expressed by means of a prior distribution with a specified upper limit. The method is hierarchical Bayes in that the uncertainty about the limit of that prior distribution is also expressed by means of a prior distribution. The data from the development program are incorporated with the prior on the unreliability and with the prior on the upper limit of the prior to obtain a new prior on unreliability. The production data are then used to obtain a revised estimate of the unreliability as well as a modified value for the limit of the prior distribution. This same concept will be carried through when the field data are obtained. The result is a final Bayesian reliability assessment that is iterative in nature and incorporates in a sequential fashion data from each of the three stages common to a component development, production, and surveillance program. 4 refs., 2 tabs.
The tungsten subfluoride mechanism as well as other proposed mechanisms of selectivity loss are reviewed. To further demonstrate the viability of the tungsten subfluoride mechanism, we have extended the measurement of the tungsten subfluoride production rate down to 450{degree}C. We also report results from some preliminary experiments designed to identify the selectivity loss mechanism when elemental silicon is available for reaction. Comments regarding the origins of the insulator effect and selectivity loss for silane reduction are offered. 23 refs., 2 figs.
The use of NUREG-1150 and similar Probabilistic Risk Assessments in NRC and industry risk management programs is discussed. Risk management'' is more comprehensive than the commonly used term accident management.'' Accident management includes strategies to prevent vessel breach, mitigate radionuclide releases from the reactor coolant system, and mitigate radionuclide releases to the environment. Risk management also addresses prevention of accident initiators, prevention of core damage, and implementation of effective emergency response procedures. The methods and results produced in NUREG-1150 provide a framework within which current risk management strategies can be evaluated, and future risk management programs can be developed and assessed. Examples of the use of the NUREG-1150 framework for identifying and evaluating risk management options are presented. All phases of risk management are discussed, with particular attention given to the early phases of accidents. Plans and methods for evaluating accident management strategies that have been identified in the NRC accident management program are discussed. 2 refs., 3 figs.
A new interfacial force microscope capable of measuring the forces between two surfaces over the entire range of surface separations, up to contact, has been developed. The design is centered around a differential capacitance displacement sensor where the common capacitor plate is supported by torsion bars. A force-feedback control system balances the interfacial forces at the sensor, maintaining the common capacitor plate at its rest position. This control eliminates the instability which occurs with the conventional cantilever-based force sensors when the attractive force gradient exceeds the mechanical stiffness of the cantilever. The ability to measure interfacial forces at surface separations smaller than this instability point using the feedback control is demonstrated. 11 refs., 3 figs.
The lowest excited electronic state of molecular oxygen, singlet oxygen ({sup 1}{Delta}{sub g}0{sub 2}), can be produced in solid organic polymers by a variety of different methods. Once produced, singlet oxygen will return to the ground triplet state by two pathways, radiative (phosphorescence) and non-radiative decay. Although the quantum efficiency of phosphorescence is small ({minus}10{sup {minus}5}), singlet oxygen can be detected by its emission at 1270 mn in both steady-state and time-resolved experiments. The phosphorescence of singlet oxygen can be used to characterize many properties of a solid organic polymer. 2 refs., 5 figs.
We review our work on multi component polymeric nonlinear optical materials. These materials consist of nonlinear optical molecules incorporated in a polymeric host. A cross-linked triazine polymer incorporating a dicyanovinyl terminated azo dye was found to be relatively stable at 85{degree} and posses an electro-optic coefficient of 11pm/V. We have also observed the zero dispersion condition in a new anomalous dispersion dye for phase matched second harmonic generation, and expect efficient conversion to the blue. A squarylium dye, ISQ, has been found to posses a large third order nonlinearity, and may display two-level behavior. 24 refs., 11 figs.
ULSI manufacturing technologies have resulted in the development of Ultra-Pure Processing (UPP) capabilities for the world-wide semiconductor industry. The primary goal of Ultra Pure Processing is the elimination of extraneous contaminants, both gaseous and particulate, from the wafer process environment. This calls for a comprehensive approach to the design, operation, and maintenance of semiconductor process equipment. Through UPP one may reduce the number of uncontrolled variables within a system enhancing implementation of Statistical Process Control on the process environment within the tool (in situ). Greater control over the process environment translates into increased product quality, manufacturability, throughput and yield. Instituting UPP requires the capability of monitoring contaminants in the process environment a well as a systematic approach to isolating and eliminating contamination sources. Ultra Pure Processing can result from a Contamination Reduction Program. Presented here are the results from a Contamination Reduction Program performed on a state-of-the-art vertical thermal process reactor (VTR). 8 figs., 5 tabs.
Most previous Probabilistic Risk Assessments have excluded consideration of accidents initiated in low power and shutdown modes of operation. A study of the risk associated with operation in low power and shutdown is being performed at Sandia National Laboratories for a US Boiling Water Reactor (BWR). This paper describes the proposed methodology for the analysis of the risk associated with the operation of a BWR during low power and shutdown modes and presents preliminary information resulting from the application of the methodology. 2 refs., 2 tabs.
In this paper we formulate a speech coding system that incorporates trellis coded vector quantization (TCVQ) and adaptive predictive coding (APC). A method for optimizing'' the TCVQ codebooks is presented and experimental results concerning survivor path mergings are reported. Simulation results are given for encoding rates of 16 and 9.6 kbps for a variety of coder parameters. The quality of the encoded speech is deemed excellent at an encoding rate of 16 kbps and very good at 9.6 kbps. 13 refs., 2 figs., 4 tabs.
The Institute of Certified Records Managers (ICRM) is a non-profit, certifying organization of professional records managers and administrators. ICRM members are experienced in information requirements, records and information systems, and the related office systems and technologies. All members have met certification requirements and have received the Certified Records Manager (CRM) designation. As the field of information and records management moves toward standardization, and as the application of new technologies and technicalities complicate the measurement and demonstration of professional competence, the need for a means of identifying persons who have basic competency increases. The ICRM is providing such a means by testing and certifying basic knowledge. More and more job announcements are requiring this evidence of competency. Unfortunately, as an organization, NIRMA has a relatively small number of CRMs. The goal of the ICRM Development Group is two-fold; (1) to encourage NIRMA members to obtain their certification by providing basic information and support and; (2) to develop the Nuclear Specialist test module which will demonstrate that bearers have demonstrated expertise in nuclear records management as well as basic competencies. This report covers the examination process.
The Nuclear Information and Records Management Association (NIRMA) Task Force on Requirements Identification is currently involved in a four part project. During the course of the next year the Task Force will: (1) identify the generic requirements documents which have common applicability to nuclear utilities and DOE organizations; (2) research the requirements documents to identify individual requirements; (3) develop and implement a PC based tracking system to present and maintain the research data; and (4) implement a process for ongoing review of requirements. This report discusses these issues.
Multiplexer and amplifier systems must be designed with transistors that can perform satisfactorily over ten years to a total gamma dose of 120E6 rads and a total neutron fluence of 1.6E15 nvt for the SP-100 reactor system. Series of gamma and neutron tests have been completed to measure transistor degradation as a function of total dose, fluence, and temperature. Test results indicate that modest increases in temperature result in substantial improvement of transistor performance at a neutron flux of 8E8 n/cm{sup 2}/s. 2 refs., 3 figs.
Critical Heat Flux (CHF), also called burnout, is one of the major design limits for water-cooled divertors in tokamaks. Another important design issue is the correct thermal modeling of the divertor plate geometry where heat is applied to only one side of the plate and highly subcooled flow boiling in internal passages is used for heat removal. This paper discusses analytical techniques developed to address these design issues, and the experimental evidence gathered in support of the approach. Typical water-cooled divertor designs for the International Thermonuclear Experimental Reactor (ITER) are analyzed, and design margins estimated. Peaking of the heat flux at the tube-water boundary is shown to be an important issue, and design concerns which could lead to imposing large design safety margins are identified. The use of flow enhancement techniques such as internal twisted tapes and fins are discussed, and some estimates of the gains in the design margin are presented. Finally, unresolved issues and concerns regarding hydraulic design of divertors are summarized, and some experiments which could help the ITER final design process identified. 23 refs., 10 figs.
Our previous calorimetric studies of weld melting efficiency and arc efficiency in the GTAW and PAW processes have naturally led us to speculate as to the magnitude of the efficiencies in the LBW process which to data have also not been adequately investigated. Most welding engineers that have had experience with the LBW process are acutely aware that the metals' absorptivity, the surface finish, and the laser wavelength, all play an important role in affecting the energy transfer efficiency, but the extent of their influence and our understanding of the influence of other process variables is not well understood. In addition, it is widely thought that only the LBW or EBW processes can be selected for applications where thermal damage and distortion from the welding process must be kept to a minimum. For these reasons, we have looked forward to performing these calorimetric experiments since they potentially can answer such important questions as: whether or not the melting efficiency of the LBW process is superior to that obtainable with conventional GTAW and PAW welding processes This study was prompted by poor production yields on switching device due to cracking of the ceramic header after final closure welding with the CO{sub 2} LBW process. This calorimetric study was begun in hopes of determining if allowed variations in production process control variables were responsible for increases in heat input and the resulting thermal stresses. By measuring the net heat input to the workpiece with the calorimeter and by measuring the laser output energy and the weld fusion zone size it was possible to determine the magnitudes of both the energy transfer efficiency and the melting efficiency as well as observe their dependence on the process variables. 3 refs.
Component test plans are often designed by allocating a system's reliability goal among the system's components, then designing individual component test plans suitable for demonstrating achievement of each component's reliability goal. One use of the resulting component test data is the calculation of estimated system reliability, based on a model linking the component reliabilities to system reliability. The statistical precision of this system estimate depends on the component test plans (numbers of each component tested and the type of tests, e.g., variables or attributes) and, hence, is determined by the component test planners. Because system reliability may be of considerable interest, we feel an integrated view of component testing is required to assure that the ensemble of component tests will provide an adequate system reliability estimate. This paper considers the case of a series system of different components and binomial component data. For the case of equal numbers of units tested of each component (which can be shown to minimize total cost, subject to the risk constraints) the O.C. envelope is readily derived and from this envelope component test plans that satisfy the specified risks can be derived from equations that involve the cumulative binomial distribution function. Existing tables pertaining to acceptance sampling plans based on the binomial distribution can be used to determine the required number of component tests. 10 refs., 2 figs.
Weak formulations in Analytical Dynamics are developed, paralleling the variational methods in elastostatics, and including a fundamental yet novel approach for treating constraints (both holonomic and nonholonomic). A general three field approach is presented, in which the momentum balance conditions, the compatibility conditions between displacement and velocity, the constitutive relations and the displacement and momentum boundary conditions are all enforced in weak form. A primal, or kinematic formulation is developed from the general form by enforcing the compatibility conditions and displacement boundary conditions a priori. The conditional stability of the kinematic formulation is the counterpart of the locking phenomenon in elastostatics and may be avoided, either by reduced order integration, or by utilizing a mixed formulation. Toward this end, a two field mixed formulation is presented, which follows from the general form, when the constitutive relations are satisfied a priori. A general set of the constraint equations are introduced into the kinematic and mixed formulations, using a specific choice of multipliers, which results in modified variational principles. Several simple examples concerning rigid body dynamics are presented. 15 refs., 18 figs.
This paper describes arc discharge tests conducted in a prepressurized, constant-volume pressure vessel to study arc behavior over a wide range of current densities, discharge durations and initial vessel pressures. This method allows controlled access to a wider range of conditions than those previously studied in capillary tests. We have investigated aspects of the radiative heat transfer by calculating the material opacity and mean free paths of photons for conditions typical of arc diagnostics. We also performed one-dimensional Eulerian hydrodynamic calculations of the boundary layer behavior in the radiative diffusion approximation. These calculations, which describe the radial mass flow and heat transfer in the absence of turbulent flow effects, show the characteristic times for equilibrium of the high-pressure arc. Finally, we describe progress on a promising means for increasing the mass flux from the capillary discharge through the use of chemically reactive media on the capillary walls. 20 refs., 7 figs.
Integrated circuit logic states are maintained by virtue of specific transistor combinations being either on'' (conducting) or off'' (nonconducting). High energy ion strikes on the microcircuit generate photocurrents whose primary detrimental effect is to make off'' transistors appear on,'' confusing the logic state and leading to single event upset (SEU). Protection against these soft errors is accomplished using either technology or circuit techniques, actions that generally impact yield and performance relative to unhardened circuits. We describe, and using circuit simulations analyze, a technique for hardening latches which requires combinations of technology and circuit modifications, but which provides SEU immunity without loss of speed. Specifically, a single logic state is hardened against SEU using technology methods and the information concerning valid states is then used to simplify hardened circuit design. The technique emphasizes some basic hardening concepts, ideas for which will be reviewed. 3 refs., 2 figs.
Fabrication of high-efficiency silicon solar cells requires processing technology capable of maintaining long bulk carrier lifetime and low surface recombination. Development of long-lifetime processing techniques using experimental designs based on statistical methods is described. The first three experiments investigated pre-oxidation cleans, phosphorus gettering, and a comparison of different phosphorus diffusion sources. Optimal processing parameters were found to depend on type of silicon material. 2 refs., 2 figs., 2 tabs.
Thin film ferroelectric materials are the basis for a new, promising IC nonvolatile memory technology. The primary material being studied for ferroelectric memories is PZT. One of the key factors in determining the feasibility of PZT ferroelectric memories for weapon or space applications is whether PZT ferroelectric technology can be integrated into a radiation-hardened CMOS or bipolar process. Sandia National Laboratories has a program to study ferroelectric/CMOS process integration issues. The primary goal of this program is to determine if radiation-hardened reliable ferroelectric/CMOS IC memories can be fabricated. This program includes both the fabrication and characterization of ferroelectric test capacitors. In this paper we will give a brief overview of the program, discuss techniques developed to characterize ferroelectric devices for retention and endurance, and give results on studies of fatigue and retention of capacitors.
A travelling wave Faraday effect fiber current sensor, consisting of a helical optical fiber coil immersed in a dielectric medium, has been demonstrated. Improved phase matching conditions have led to measured bandwidth enhancements of greater than a factor of four. Sensitive devices with multi-gigahertz bandwidths are possible using this technique. 7 refs., 3 figs.
The authors present sufficient conditions for the design of strictly positive real (SPR), fixed-order dynamic compensators. The primary motivation for designing SPR compensators is for application to positive real (PR) plants. When an SPR compensator is connected to a PR plant in a negative feedback configuration, the closed loop is guaranteed stable for arbitrary plant variations as long as the plant remains PR. Equations that are a modified form of the optimal projection equations, with the separation principle not holding in either the full- or reduced-order case, are given. A solution to the design equations in shown to exist when the plant is PR (or just stable). Finally, the closed-loop system consisting of a PR plant and an SPR compensator is shown to be S-structured Lyapunov stable.
A Nuisance Alarm Data System (NADS) was developed to gather long-term background alarm data on exterior intrusion detectors as part of their evaluation. Since nuisance alarms play an important part in the selection of intrusion detectors for use at Department of Energy (DOE) facilities, an economical and reliable way to monitor and record these alarms was needed. NADS consists of an IBM Personal Computer and printer along with other commercial units to communicate with the detectors, to gather weather data and to record video for assessment. Each alarm, its assessment and the weather conditions occurring at alarm time are placed into a database that is used in the evaluation of the detector. The operating software is written in Turbo Pascal for easy maintenance and modification. A portable system, based on the NADS design, has been built and shipped to other DOE locations to do on-site alarm monitoring. This has been valuable for the comparison of different detectors in the on-site environment and for testing new detectors when the appropriate conditions do not exist or cannot be simulated at the Exterior Intrusion Detection Testbed.
A 2D-Laser Radar Imaging System consisting of a prototype 2D-Laser Radar Sensor and an Image Processing System is currently being developed as an intrusion detection system capable of immediate detection and quick assessment for perimeter security and surveillance. The objective of this system is to produce a thin laser wall as an invisible intrusion barrier. Since only a small space is needed to create a narrow laser radar wall, this system will work well where there is only limited or narrow zones available to create the secure perimeter. Images are created of objects which penetrate the laser radar wall for assessment and to determine the appropriate alarm response. Such a system can be used to protect against airborne threats from rooftop areas or to guard against ground threats across perimeter zones of critical facilities. This paper will discuss the operational concepts, the technology, and an initial performance of this prototype system. 2 refs., 6 figs.
Technical Digest, 1990 Solid-State Sensor and Actuator Workshop
Frye, G.C.; Brinker, C.J.; Ashley, C.S.; Martinez, S.L.; Bein, T.
The use of porous oxide coatings, formed using sol-gel chemistry routes, as the discriminating elements of acoustic wave (AW) chemical sensors, is investigated. These coatings provide several unique advantages: durability, high adsorption capacity based on large surface areas, and chemical selectivity based on both molecular size and chemical interactions. The porosity of these coatings is determined by performing nitrogen adsorption isotherms using the AW device response to monitor the uptake of nitrogen at 77 K. The chemical sensitivity and selectivity obtained with this class of coatings is demonstrated using several examples: hydrous titanate ion exchange coatings, zeolite/silicate microcomposite coatings, and surface modified silicate films.
In light sources such as tungsten filament bulbs, fluorescent tubes and gas tube type radioluminescent (RL) lamps, visible light is emitted from a thin surface layer of excited material. In contrast, neon bulbs, xenon flash tubes and lasers emit light generated throughout their volumes. The first group can be characterized as surface emitters and the latter as volumetric emitters. Theoretically, an ideal volumetric light source has definite advantages over a surface source. In reality, practical volumetric sources will have limitations as well. These advantages and limitations will be discussed with particular emphasis on comparisons between current gas tube type RL lamps and the more advanced volumetric RL lamps.
A new generation of digital multimeters was used to compare the ratios of the resistances of wire-wound reference resistors and quantized Hall resistances. The accuracies are better than 0.1 ppM for ratios as large as 4:1 if the multimeters are calibrated with a Josephson array. 9 refs.
Constitutive modeling and bifurcation analyses are combined with axisymmetric (triaxial), triaxial/torsion, and plane-strain experiments to interpret and anticipate the development of shear localization in rocks. This paper discusses preliminary results. 22 refs., 3 figs.
The US Department of Energy (DOE) has supported the development of the sodium-sulfur technology since 1973. The programs have focused on progressing core aspects of the technology and completing initial battery engineering for both mobile and stationary applications. An overview of the Office of Energy Management (OEM) activities is contained in this paper. Two major development programs have been active: the first with Ford Aerospace and Communications Corporation (1975 to 1985), and the second with Chloride Silent Power Limited (1985 to 1990). With the completion this year of the qualification of a cell suitable for initial Solar Energy Systems (SES) applications, the emphasis of future DOE/OEM sodium/sulfur programs will shift to SES-battery engineering and development. The initial effort will resolve a number of issues related to the feasibility of utilizing the sodium/sulfur technology in these large-scale applications. This multi-year activity will represent the initial phase of an integrated long-term DOE-supported program to produce a commercially viable battery system.
The integrity of many mechanical assemblies and electrical components depends on small threaded fasteners. The design standards for small (less than {1/4} inch in diameter) screws made of stainless steel are not as well developed as those for larger sizes of high strength steels. The typical design approach is based on the application of static design principals. Steady state accelerations are applied to the component or assembly and sufficient screws are installed in mounting hardware for attachment to the next assembly. These design principals have been used successfully for years in a wide variety of applications. As the parts requiring small screws have continued to decrease in size, some design requirements include greater thread depths and adherence to strict interpretation of the governing thread standards. These design requirements have their origins in the lack of adequate definitions and standards for designs using small threaded fasteners. These design practices have led to significant problems in manufacturing parts with small threaded fasteners by requiring thread depths to four and more diameters of engagement while maintaining thread heights (radial engagement) of 75 percent throughout the thread interfaces. A test program was developed to address questions regarding design and manufacturing issues involving small threaded fasteners which included tensile strength, length of engagement needed to achieve the full strengths of the screws, and verification of the static design principals in dynamic conditions. This paper summarizes the initial results obtained to date from this test program and describes the work-in-progress on the dynamic tests with their related static tests. 2 refs., 4 figs., 4 tabs.
An isotropic continuum damage theory which accounts for the degradation of material strength under quasi-static loading conditions has been developed in the present investigation. The damage mechanism in this theory has been selected to be the interaction and growth of subscale cracks. The development of the theory follows closely the strain-rate dependent dynamic model advanced by the first author and his coworkers. Briefly, the cracks are activated by the maximum principal tensile strain and the density of activated cracks is described by a Weibull statistical distribution. The moduli of a cracked solid derived by Budiansky and O'Connell are then used to represent the global material degradation due to subscale cracking. Two additional material constants have been introduced in this model. These constants are determined from uniaxial tensile test data. The model has been implemented into a finite element code. Sample calculations involving the uniaxial and biaxial responses of plain concrete panels are presented to demonstrate the utility of the model. 7 refs., 2 figs.
The first in a series of multi-factor experiments designed to optimize the chemical cleaning procedure for four types of silicon material used in solar cell fabrication has been completed. The goal of this first experiment (a twenty-two factor main-effects experiment) was to determine the factors associated with chemical cleaning procedures that are most important in obtaining high excess charge-carrier recombination lifetime following a high-temperature furnace oxidation. It was determined that the factors having the strongest influence on charge-carrier lifetime were different for the four different silicon materials considered. In general, the lower the lifetime of the material, the less sensitive the material was to different chemical cleaning steps. The stability of the lifetime was also evaluated with several factors exhibiting a significant effect for high-quality silicon. Chemical cleaning procedures were identified that resulted in stable post-oxidation lifetimes greater than 2 ms for high-resistivity float-zone silicon. 3 refs., 8 figs.
The closure measurements from a large scale, heated, in situ experimental room in salt are compared to numerical calculations using the most recent predictive technology, with very good agreement, limited potentially only by the unmodeled roof fracture and separation.
Insulations are used in metallic glass ribbon cores in pulse power applications to prevent interlaminar eddy currents due to voltages induced between adjacent laminations. These interlaminar eddy currents can greatly increase the losses in cores, and, thereby, decrease the pulse permeability at high magnetization rates. This paper reports results of experiments with various insulation materials and both low and high induced anisotropy energy iron-base metallic glass ribbons. Co-wound insulation films as well as conformal insulations were investigated. Magnetic properties and voltage hold-off strengths are reported. 11 refs., 11 figs., 5 tabs.
When quartz controlled oscillators are required for use in applications demanding precision many factors will ultimately place limitations on the ability of the oscillator to remain at the desired frequency. These factors include temperature, resonator Q, pullability, radiation, output load variability, and the electronic components. This paper addresses the subject of frequency instability of oscillator circuits due to power supply voltage variations. In particular, the primary sources of this instability are described for a Pierce oscillator employing a bipolar transistor and design techniques are presented which minimize these frequency pulling effects. 4 refs., 17 figs.
The three-dimensional structural analysis of reentry vehicles presents a considerable challenge to the analyst. This is due to the mechanics of the problem as well as the incorporation of results from several disciplines into the environmental description of the problem. Separate results from aero-analyses, frequently computed in one-dimensional format must be combined into a three-dimensional format suitable for a structural finite element analysis. Features required for the analysis include the ablated thickness of the heatshield structure, as well as pressure on the vehicle and the temperature distribution through the heatshield. By combining these environments, a complete description of all factors which affect the structural performance of reentry vehicles are included into one analysis. This paper presents a method of analyzing the structural response of reentry vehicles using the complete three-dimensional environmental load description.
Reflection Mass Spectrometry (REMS) consists of a cryo-shrouded mass spectrometer which measures mass-analyzed, line-of-sight chemical fluxes from a growing wafer. It is especially useful during III/V molecular beam epitaxy (MBE) for which there are always substantial group V fluxes and often some group III fluxes leaving the wafer during growth. These fluxes depend sensitively on the instantaneous chemical reactivity of the surface. That chemical reactivity in turn depends on instantaneous alloy composition (III/III ratio), surface stoichiometry (As coverage) and temperature. In this brief summary of our work, we describe two examples of the engineering'' usefulness of REMS, involving MBE of InAlAs and InGaAs and one example of measurements of basic scientific interest. 3 figs.
A program is under way to develop liquid metal heat pipes that can transfer energy from the focal point of a parabolic solar concentrator to the heater tubes of one or more Stirling engines. To design high performance wicks for heat pipe solar receivers, it is necessary to have an accurate assessment of the wick's properties. Procedures for measuring the flow properties of wicks before and after fabrication processes take place are presented. The testing procedures provide a useful method of determining the validity of a wick design before full-scale testing is attempted.
Significant progress is continuing in the development of photovoltaic (PV) concentrator technology. New record cell and module efficiencies have been achieved, and improvements in cells, cell assemblies, and modules are increasing reliability and decreasing cost. The number of firms actively pursuing PV concentrator module technology has increased substantially in the last three years. Two new concentrator systems were installed last year, and we are likely to see more in the near future. This paper describes the most significant developments of the last two years, including descriptions of PV concentrator module development and reliability activities, advances in concentrator cell technology, the new PV concentrator array installations, a new Concentrator Initiative Program, and results of the latest costing study. 26 refs., 9 figs., 1 tab.
Chacahoula salt dome, eight miles southwest of Thibodaux, LA, could be solution mined to create caverns for storing as much as 500 million barrels (MMB) of crude oil, should the Strategic Petroleum Reserve (SPR) require additional storage volume. The salt mass geometry is confirmed by more than 50 oil wells, and also from previous exploratory drilling for sulphur. Top of salt occurs at {minus}1100 ft, and some 1300 acres exist within the {minus}2000 ft salt contour. Frasch mining of 1.35 million long tons of sulphur caused the surface to subside about one foot on the northeastern part of the dome. Creep-induced subsidence averaging {approximately}2.7 ft over 30 yrs is estimated for a 200 MMB cavern array, which would require perimeter diking to control localized perennial flooding. Earthquakes approaching intensity MM 6 have occurred nearby and are expected to recur on the order of {approximately}100 yrs but would not affect cavern stability. Additional study of brine disposal methods and hurricane surge probabilities are needed to establish design parameters and cost estimates for storage. 11 refs., 8 figs., 2 tabs.
A Nuisance Alarm Data System (NADS) was developed to gather long- term background alarm data on exterior intrusion detectors as part of their evaluation. Since nuisance alarms play an important part in the selection of intrusion detectors for use at Department of Energy (DOE) facilities, an economical and reliable way to monitor and record there alarms was needed. NADS consists of an IBM Personal Computer and printer along with other commercial units to communicate with detectors, to gather weather data and to record video for assessment. Each alarm, its assessment and the weather conditions occurring at alarm time are placed into a database that is used in the evaluation of the detector. The operating software is written in Turbo Pascal for easy maintenance and modification. A portable system, based on the NADS design, has been built and shipped to other DOE locations to do on-site alarm monitoring. This has been valuable for the comparison of different detectors in the on-site environment and for testing new detectors when the appropriate conditions do not exist or cannot be simulated at the Exterior Intrusion Detection Testbed.
A molten salt cavity receiver was solar tested at Sandia National Laboratories during a year-long test program. Upon completion of testing, an analysis was performed to determine the effect of thermal cycling on the receiver. The results indicate substantial fatigue damage accumulation for the receiver when the relatively short test time is considered. This paper describes the methodology used to analyze the cycling, the results, and how they affect future receiver design. The test receiver was configured as a C-shaped cavity with eight multipass heat absorption panels. The tubes were Alloy 800. The heat exchange medium was a molten nitrate salt mixture (60% sodium nitrate, 40% potassium nitrate by weight). The operating temperature range was from 288°C to 566°C.
Under compressive stresses, brittle polycrystalline materials fail as the result of the growth, interaction and coalesence of microcracks. To predict the deformation of damaging material, constitutive laws developed for such materials must incorporate the effects of crack size, density, orientation, and interaction.A method of incorporating the accumulation and growth of microcracks into a continuum model is to use a measure of microcrack growth and interaction defined as damage. Although a number of damage theories have been proposed, there is no generally accepted experimental technique for detecting and measuring damage. Acoustic emissions (AE) have been correlated with microcrack nucleation and growth. We propose that AE locations and density are useful measures of damage that can be correlated with calculated damage. Our approach is to use acoustic emissions (AE) and computer modeling to study the development of damage in geomaterials.
Consideration is given to the problem of stabilizing a plant using a suboptimal stable compensator of fixed order. The resulting equations are a modified form of the optimal projection equations, with the separation principle not holding in either the full- or reduced-order case. An overbounding technique on the state covariance guarantees that the compensator is stable if nonnegative definite solutions exist to the design equations.
The Function Point (FP) concept was introduced to define'' a measure for applications development and maintenance functions avoiding the problems inherent in productivity measures in the late 1970s. At that time, Albrecht outlines three essentials elements for software size measurement: the measure must be technology independent; the technique must measure all the application functions delivered to the end customer; and the technique must measure only the application functions as delivered. Using these three attributes of a measurement, further concentrated analysis could be performed for languages, technologies, methodologies, and tools. The characterization of systems and the quality of the product are motives for subscribing to FPs. Since the inception of FPs, attempts have been made to improve the process of quantifying FPs. Some of these attempts have strayed from the intended use of FPs and have diverted valuable energy away from consistent application. The purpose of this article is to describe the process and the quantification of complexity factors for each of the five Unadjusted FPs. 4 refs.
Light ion fusion research has developed ion diodes that have unique properties when compared to other ion diodes. These diodes involve relativistic electrons, ion beam stagnation pressures that compress the magnetic field to the order of 10 Tesla, and large space-charge and particle current effects throughout the accelerating region. These diodes have required new theories and models to account for effects that previously were unimportant. One of the most important effects of the magnetic field compression and large space-charge has been impedance collapse. The impedance collapse can lead to poor energy transfer efficiency, beam debunching, and rapid change of the beam focus. This paper discusses our current understanding of these effects, some of the methods we are using to ameliorate them, and the future directions our theory and modeling will take. 40 refs., 6 figs.
A new scanning electron microscopy imaging technique has been developed to examine the logic state of conductors on passivated CMOS integrated circuits. This technique employs a modified Resistive Contrast Imaging system to acquire image data on powered devices. The image is generated by monitoring subtle shifts in the power supply current of an integrated circuit as an electron beam is scanned over the device surface. The images produced with this new technique resemble voltage contrast data from devices with the passivation removed and the surface topography subtracted. Non-destructive applications of this imaging method to functional and failed integrated circuits are described. Possible irradiation effects and methods to minimize them are also discussed. 2 refs., 1 fig.
Transit time, the time from bridgewire burst until breakout of detonation from the output pellet of an exploding bridgewire detonator, was measured as a function of burst current. From this data, in conjunction with known equations for run distance versus pressure, unreacted explosive Hugoniots, and detonation properties of the initial pressing pellet, the run distance in the initial pressing explosive pellet and shock pressure from the exploding bridgewire were determined, both as a function of burst current.
Fifteen years of solar thermal technology development have produced a considerable amount of knowledge relating to the production of electricity from central receiver power plants. This body of knowledge is under examination by researchers from the United States and the Federal Republic of Germany for the purpose of defining the next generation central receiver electricity producers. This second generation power plant is expected to represent a significant step towards commercialization of these systems. During the course of the study, specific activities needed to realize this next-step technology are being defined. The study is an international team effort. Under the International Energy Agency Small Solar Power Systems project, researchers from DLR, Interatom, Sandia National Laboratories, and Bechtel have designed a study in which technologies relating to existing systems are quantified, logical next-step systems are characterized, and future potential advances are identified. The receiver concepts under investigation are: salt-in- tube, volumetric, and direct absorption. Two plant performance levels are examined, 30 and 100 MW{sub e}. Each concept is applied with common capacity factors, solar multiples, and types and sizes of heliostats at each performance level. Availability and uncertainty analyses are also performed. Annual energy production figures are calculated using the SOLERGY computer code. Capital and Operation and Maintenance cost methodologies are mutually agreed upon in order that levelized energy cost calculations will be consistent for each power plant. During the course of this effort, further potential advances in central receiver technology have continued to become apparent. These possible areas for improvement will be described. An additional comparison is being made between central receivers and trough-based systems. 8 refs., 2 figs.
A hierarchical control architecture for telerobotic vehicles intended to yield a modular, flexible, and easily expanded control system is presented. This architecture is proposed for applications where simple teleoperation is required but where additional capabilities might be quickly added without major changes to the control system. Similarities to the NASREM architecture are noted. Results are given from hardware implementation of the control system on a telerobotic vehicle, Raybot, at Sandia National Laboratories.
A systematic study is described which addresses the technical issues associated with launching flier-plates intact to hypervelocitites. First, very high pressures are needed to launch the flier plates to hypervelocitites, and second this high pressure loading must be uniform and nearly shockless. To achieve both these criteria, a graded-density material referred to as a pillow'' is used to impact a flier plate. When this graded-density material is used to impact a flier plate at high velocities on a two-stage light-gas gun, nearly shockless megabar pressure pulses are introduced into the flier plate. Since the loading on the flier plate is shockless, melting of the flier plate is prevented. This technique has been used to launch a 2-mm thick titanium alloy (Ti-6Al-4V) plate to a velocity of 8.1 km/s, and a 1-mm thick aluminum alloy (6061-T6) plate to a velocity of 10.4 km/s. A method is described by which the flier plate velocities could be further augmented to velocities approaching 14 km/s. 18 refs., 16 figs.
A new technique is reported for the rapid determination of interstitial oxygen (O{sub i}) in heavily doped n{sup +} and p{sup +} silicon. This technique includes application of a selective electrochemical thinning (SET) process and FTIR transmittance measurement on a limited area of a silicon wafer. The O{sub i} is calculated using ASTM F1188--88 with the IOC 88 calibration factor. An advantage of SET over mechanical thinning is that the original wafer thickness and diameter are maintained for additional processing. 1 tab.
The Shippable Storage Cask Demonstration Project is intended to demonstrate casks which can be used for both shipping and storing spent nuclear fuel assemblies. The demonstration included the requirement that the casks be certified for shipping by the US Nuclear Regulatory Commission (NRC). After a lengthy review process which resulted in the resolution of several important technical issues, designs for two similar casks have been certified. This paper describes the certification phase of the demonstration. Based on experience gained during certification phase of the demonstration. Based on experience gained during certification, observations and recommendations have been developed which can benefit others seeking NRC approval of transportation cask designs.
Reviews of normal breakdown and current induced avalanche breakdown mechanisms in silicon power transistors are presented. We show the applicability of the current induced avalanche model to heavy ion induced burnouts. Finally, we present solutions to current induced avalanche in silicon power semiconductors. 7 refs., 5 figs.
The electronic properties of heavily and orderly Si-doped nipi structures in GaAs are studied theoretically using the ab-initio self-consistent pseudopotential method within the local density approximation. Two nipi configurations are considered. Besides investigating the nature of the impurity-related band edge states, the xy-planar-averaged local ionic and self-consistent potentials are also analyzed. The screening effect of the host crystal on the doping induced potential is found to be small. The effects of the doping induced electric field and the strain due to dopings are also examined. 13 refs., 9 figs., 2 tabs.
The near field surrounding buried waste in the proposed high level nuclear waste repository in Yucca Mountain, Nye County, Nevada, is a region where strongly heat driven processes can exist. These strongly heat driven processes further complicate an already very difficult problem, i.e,. predicting groundwater flow and chemical transport through unsaturated fractured, heterogeneous porous media. The coupling between fluid flow and heat emanation is central to understanding these strongly heat driven processes. Although it is important that all of couplings be investigated, the intent of this paper is to discuss the mathematical models and associated computer codes that can be used in investigating the coupled heat emanation and fluid flow in unsaturated porous media. The information in this paper should be useful to those studying these phenomena, validating these models, or investigating the coupling of fluid flow and heat emanation with the other phenomena. The codes implementing these models are commonly referred to as nonisothermal two-phase flow codes. 5 refs., 4 tabs.
The United States Department of Energy (DOE) is developing the Waste Isolation Pilot Plant (WIPP), located in southeastern New Mexico, for disposal of transuranic wastes generated by defense programs. The DOE must first demonstrate compliance with the Environmental Protection Agency's (EPA) Environmental Standards for the Management and Disposal of Spent Nuclear Fuel, High-Level and Transuranic Radioactive Wastes hereafter called the Standard. The Containment Requirements in Subpart B of the Standard set limits on the probability that cumulative radionuclide releases to the accessible environment during the 10,000 years following decommissioning of the repository will exceed certain limits. To comply with these requirements, performance assessments must construct a modeling system that can adequately simulate all realistic future states of the repository that might result in radionuclide releases. Because the regulatory limits are probabilistic, performance assessments must accurately reflect variability and uncertainty within all factors that contribute to the simulation, including variability and uncertainty within all factors that contribute to the simulation, including variability in material properties, probabilities of future human actions, and uncertainties inherent in the conceptual and numerical models that simulate reality. This paper describes conceptual and numerical improvements in the performance assessment methodology made during 1990, and summarizes the present status of WIPP performance assessment. All results to date are preliminary, and cannot be used to determine compliance or non-compliance. The DOE anticipates determining compliance after evaluating a final performance assessment in 1994. 11 refs., 3 figs.
Low pressure (200 Torr) metalorganic chemical vapor deposition (MOCVD) of InSb has been examined through variation of the Column III (TMIn) and Column V (TMSb or TESb) precursor partial pressures. The use of lower growth pressure significantly enhanced the range of allowable Column III Column V partial pressures in which specular morphology InSb could be obtained without the formation of In droplets or Sb crystals. In addition, a 70% improvement in the average hole mobility was obtained, compared to InSb grown in the same reactor at atmospheric pressure. SIMS analysis revealed that Si at the substrate/epitaxial layer interface is an important impurity that may contribute to degradation of the mobility. Substitution of TESb for TMSb did not result in any improvement in the purity of the InSb. 6 refs.
The long length and relatively small cross sectional area of the robotic arms envisioned for use inside of the underground nuclear waste storage tanks will require the control of flexible structures. This will become an important problem in the characterization and remediation of these tanks. We are developing control strategies to actively damp residual vibrations in flexible robotic arms caused by high speed motion and abrupt external forces. A planar, two-link flexible arm is currently being used to test these control strategies. In this paper, two methods of control are discussed. The first is a minimum-time control approach which utilizes a finite element model and and optimization program. These tools plan the motor torque profiles necessary for the tip of the arm to move along a straight line, in minimum time, within the motors' torque constraints, and end in a quiescent state. To account for modeling errors in the finite element model, errors in joint angles, velocities, and link curvatures are added to the optimal torque trajectory. Linear quadratic Gaussian (LQG) regulatory design theory is used to determine the feedback gains. The second method of control is a teleoperated joystick controller which uses an input shaping technique to alter the commands of the joystick so as to reduce the residual vibration of the fundamental modes. Approximating the system as linear, the natural frequency and damping ratio are estimated on-line for the complete system, which includes the structure plus a lower level proportional derivative controller. An input shaping filter is determined from the estimated natural frequency, estimated damping ratio, and the desired transfer function of the system. 11 reps., 9 figs.
Muir, J.F.; Hogan Jr., R.E.; Skocypec, R.D.; Buck, R.
The concept of solar driven chemical reactions in a commercial-scale volumetric receiver/reactor on a parabolic concentrator was successfully demonstrated in the CAtalytically Enhanced Solar Absorption Receiver (CAESAR) test. Solar reforming of methane (CH{sub 4}) with carbon dioxide (CO{sub 2}) was achieved in a 64-cm diameter direct absorption reactor on a parabolic dish capable of 150 kW solar power. The reactor was a catalytic volumetric absorber consisting of a multi-layered, porous alumina foam disk coated with rhodium (Rh) catalyst. The system was operated during both steady-state and solar transient (cloud passage) conditions. The total solar power absorbed reached values up to 97 kW and the maximum methane conversion was 70%. Receiver thermal efficiencies ranged up to 85% and chemical efficiencies peaked at 54%. The absorber performed satisfactorily in promoting the reforming reaction during the tests without carbon formation. However, problems of cracking and degradation of the porous matrix, nonuniform dispersion of the Rh through the absorber, and catalyst deactivation due to sintering and possible encapsulation, must be resolved to achieve long-term operation and eventual commercialization. 17 refs., 11 figs., 1 tab.
We have performed MD simulations of adhesive phenomena, on an atomic scale, between metals possessing both smooth and stepped-surfaces. Studies of adhesion between identical metals, consisting of either Au, Cu, or Ni, with (001) or (111) orientations, reveal the existence of adhesive avalanches as the bodies are brought to within a critical separation ({approximately}2 {angstrom}). That is, as the surfaces approach one another, one or both surface layers becomes unstable, and abruptly moves toward the other. This signals a transition from an initial system with two distinct surfaces to one possessing no identifiable surfaces. The presence of adhesive avalanches will pose difficulties in determining adhesive forces and energies by means of atomic force microscopy at sub-nanometer separations of probe tip and sample surface. 7 refs., 3 figs.
An improved standard total-dose test method is described to qualify electronics for a low-dose radiation environment typical of space systems. The method consists of {sup 60}Co irradiation at a dose rate of 1--3 Gy(Si)/s (100--300 rad(Si)/s) and a subsequent 373 K (100{degree}C) bake. New initiatives in radiation hardness assurance are also briefly discussed, including the Qualified Manufacturers List (QML) test methodology and the possible use of 1/f noise measurements as a nondestructive screen for oxide-trap charge related failure. 8 refs.
A two-stage data compression technique that provides for exact, bit-for-bit recovery is described. The first stage is a modified form of conventional linear prediction which generates an error or residue sequence in such a way that exact reconstruction of the original data sequence can be accomplished with a simple recovery algorithm. The second stage is bi-level sequence coding. Even though the residue sequence from the first stage is essential white and Gaussian with seismic or other similar waveform data, bi-level sequence coding will generally provide further compression. The complete technique is described briefly in this summary, and examples of its performance are presented. A full paper on the algorithm is available from the author. 12 refs., 2 figs., 2 tabs.
We have synthesized a new tool, a lasing phase diagram, for designing high efficiency surface-emitting laser resonators and have demonstrated its usefulness by fabricating and operating many different laser resonators. 4 refs., 4 figs.
This paper is concerned with controlling the morphology of microporous polymers prepared via thermal demixing of solutions. 2 wt % solutions of poly(acrylonitrile) in maleic anhydride, a poor solvent, are first cooled to produce separated polymer-rich and solvent-rich phases. Removing the solvent by freeze drying then produces a microporous material having a density of 33 mg/cm{sup 3}, a void fraction of 97%, and a pore size of about 10 {mu}m. We find that the morphology cannot be explained by existing models, which focus on phase diagrams and kinetics of phase transformations during cooling of the solution. In conflict with those models, we find that two radically different morphologies can be produced even when the polymer concentration and cooling path are held strictly constant. A hypothesis that polymer degradation causes the different morphologies is not supported by GPC, {sup 13}C NMR, and FTIR experiments. Instead, we offer evidence that the different microporous morphologies are caused by different polymer conformations in solutions having the same concentration and temperature. 11 refs., 3 figs.
The nuclear industry uses sensitive or classified parts and material that must be protected and accounted for. We believe there is a need for an automated system that can help protect and inventory these parts and material. In response to this need Sandia National Laboratories Division 5245 is developing a personnel and material tracking system named PAMTRAK to safeguard sensitive parts and material at selected Department of Energy facilities. This paper describes the project's background, design goals and features.