Publications

The goal of the Stretched-Membrane Dish Program is the development of a dish solar concentrator fabricated with a single optical element capable of collecting 60 kWt. Solar Kinetics, Inc., has constructed a prototype 7-meter dish to demonstrate the manufacturability and optical performance of this innovative design. The reflective surface of the dish consists of a plastically deformed metal membrane with a separate reflective polymer membrane on top, both held in place by a low-level vacuum. Sandia conducted a test program to determine the on-sum performance of the dish. The vacuum setting was varied 8.9- to 17. 2-cm of water column and the vertex to target distance was varied over a range of 15.24 cm to evaluate beam quality. The optimal setting for the vacuum was 11.4 centimeters of water column with the best beam quality of 6.4 centimeters behind the theoretical focal point of the dish. Flux arrays based on slope error from the CIRCE2 computer code were compared to the measured flux array of the dish. The uniformly distributed slope error of 2.3 milliradians was determined as the value that would produce a modeled array with the minimum mean square difference to the measured array. Cold water calorimetry measured a power of 23.3 {plus minus} .3 kWt. Reflectivity change from an initial value of 88.3% to 76.7% over a one year period. 12 refs.

Pulsed high field magnet coils are an integral part of the applied-B ion diode used in the light ion Inertial Confinement Fusion program at Sandia National Laboratories. Several factors have contributed in recent years to the need for higher magnetic fields of these applied-B ion diodes. These increased magnetic field requirements have precipitated the development of better engineering tools and techniques for use in the design of applied-B ion diodes. This paper describes the status of the applied-B ion diode engineering at Sandia. The design process and considerations are discussed. A systematic approach for maximizing the field achievable from a particular coil system consisting of the capacitor bank, the feeds, and the coil is presented. A coupled electromechanical finite element analysis is also described.

Rock mechanisms parameters such as the in situ stresses, elastic properties, failure characteristics, and poro-elastic response are important to most completion and stimulation operations. Perforating, hydraulic fracturing, wellbore stability, and sand production are examples of technology that are largely controlled by the rock mechanics of the process. While much research has been performed in these areas, there has been insufficient application that research by industry. In addition, there are new research needs that must be addressed for technology advancement.

We describe the use of the object-oriented language C++ in the development of a hydrocode simulation system, PCTH. The system is designed to be horizontally and vertically portable from low-end workstations to next generation massively parallel supercomputers. The development of the PCTH system and the issues and rationale considered in moving to the object oriented paradigm will be discussed.

The goals and time constraints of developing the next generation shock code, RHALE++, for the Computational Dynamics and Adaptive Structures Department at Sandia National Laboratories have forced the development team to closely examine their program development environment. After a thorough investigation of possible programming languages, the development team has switched from a FORTRAN programming environment to C++. This decision is based on the flexibility, strong type checking, and object-oriented features of the C++ programming language. RHALE++ is a three dimensional, multi-material, arbitrary Lagrangian Eulerian hydrocode. Currently, RHALE++ is being developed for von Neumann, vector, and MIMD/SIMD computer architectures. Using the object oriented features of C++ facilitates development on these different computer architectures since architecture dependences such as inter processor communication, can be hidden in base classes. However, the object oriented features of the language can create significant losses in efficiency and memory utilization. Techniques, such as reference counting, have been developed to address efficiency problems that are inherent in the language. Presently, there has been very little efficiency loss realized on SUN scalar and nCUBE massively parallel computers; however, although some vectorization has been accomplished on CRAY systems, significant efficiency losses exist. This paper presents the current status of using C++ as the development language for RHALE++ and the efficiency that has been realized on SUN, CRAY, and nCUBE systems.

Depleted uranium (DU) is used in high level radioactive waste transport containers as a gamma shield. The mechanical response of this material has generally not been included in calculations intended to assure that these casks will maintain their containment function during all normal use and accident conditions. If DU could be qualified as a structural component, the thickness of other materials (e.g. stainless steel) in the primary containment boundary could be reduced, thereby allowing a reduction in cask mass and/or an increase in payload capacity. This study was conducted to determine the mechanical behavior of a range of DU alloys in order to extend the limited set of mechanical properties reported in the literature. These mechanical properties were used as the basis for finite element calculations to quantify the potential for claiming structural credit for DU.

Variations of bed void fraction in a full-scale, reacting, fixed-bed coal gasifier have been deduced from measured axial pressure profiles obtained during gasification of seven coal types ranging from lignite to bituminous. Packed-bed pressure correlations were used to calculate the void fractions based on monotonic polynomial fits of measured pressure profiles. Insights into the fixed-bed combustion processes affected by the void distribution were obtained by a one-dimensional, steady-state, fixed-bed combustion model. Predicted temperature profiles from this model compare reasonably well to experimental data. The bed void distributions are not linear but are perturbed by vigorous reactions in the devolatilization and oxidation zones. Results indicate that a dramatic increase in temperature and associated gas release causes the bed to expand and the gas void space to increase. Increased void space localized in the combustion zone causes the steep temperature gradient to decrease and the location of the maximum temperature to shift. Also, large feed gas flow rates cause the void fraction in the ash zone to increase.

Crosshole shear-wave seismic surveys have been used to monitor the distribution of injected air in the subsurface during an in situ air stripping waste remediation project at the Savannah River site in South Carolina. To remove the contaminant, in this case TCE`s from a leaking sewer line, two horizontal wells were drilled at depths of 20 m and 52 m. Air was pumped into the lower well and a vacuum was applied to the upper well to extract the injected air. As the air passed through the subsurface, TCE`s were dissolved into the gas and brought out the extraction well. Monitoring of the air injection by crosshole shear wave seismics is feasible due to the changes in soil saturation during injection resulting in a corresponding change in seismic velocities. Using a downhole shear-wave source and clamped downhole receiver, two sets of shear-wave data were taken. The first data were taken before the start of air injection, and the second taken during. The difference in travel times between the two data sets were tomographically inverted to obtain velocity differences. Velocity changes ranging up to 3% were mapped corresponding to saturation changes up to 24%. The distribution of these changes shows a desaturation around the position of the injection well with a plume extending in the direction of the extraction well. Layers with higher clay content show distinctively less change in saturation than the regions with higher sand content.

Numerical optimization has been successfully used to obtain optimal designs in a more efficient and structured manner in many industries. Optimization of sizing variables is already a widely used design tool and even though shape optimization is still an active research topic, significant successes have been achieved for many structural analysis problems. The transportation cask design problem seems to have the formulation and requirements to benefit from numerical optimization. Complex structural, thermal and radiation shielding analyses associated with cask design constraints can be integrated and automated through numerical optimization to help meet the growing needs for safe and reliable shipping containers. Improved overall package safety and efficiency with cost savings in the design and fabrication can also be realized. Sandia National Laboratories (SNL) has the opportunity to be a significant contributor in the development of new sophisticated transportation cask design tools. Current state-of-the-art technology at SNL in the areas of structural mechanics, thermal mechanics, numerical analysis, adaptive finite element analysis, automatic mesh generation, and transportation cask design can be combined to enhance current industry-standard cask design and analysis techniques through numerical optimization.

This report describes in details the operations necessary to perform a test on the Sandia National Laboratories 18-Inch Actuator. This report is to sever as a training aid for personnel learning to operate the Actuator. A complete description of the construction and operation of the Actuator is also given. The control system, data acquisition system, and high-pressure air supply system are also described. Detailed checklists, with an emphasis on safety, are presented for test operations and for maintenance.

The Hazardous Material Identification Process is a guide to pre-characterization of excess weapon hardware for environmental and safety hazards prior to introduction of the hardware into a waste stream. A procedure for planning predisposal processing of hardware for declassification, demilitarization, and separation/expenditure of certain hazards is included. Final characterization of the resultant waste streams is left to the cognizant waste management agency or organization.

The 2-D code MAGIC and TRAJ have been used for extensive studies of diode, IFR channel, and accelerating gap problems in the recirculating linear accelerator (RLA). Typical beam parameters use 10--20 kA, 3--4 MeV. This report summarizes recent results from these simulations. We have also designed possible injectors for the proposed BOLT experiment, with typical beams at 100 A, 1.0--1.5 MeV. Finally, we discuss some preliminary diode runs of proposed 100 MV, 500 kA accelerator using the SMILE/HERMES method of adding voltages from many cavities across a single immersed diode gap. 8 refs.

This report describes the progress of the three-dimensional mesh generation research, using plastering, during the 1990 fiscal year. Plastering is a 3-D extension of the two-dimensional paving technique. The objective is to fill an arbitrary volume with hexahedral elements. The plastering algorithm`s approach to the problem is to remove rows of elements from the exterior of the volume. Elements are removed, one level at a time, until the volume vanishes. Special closure algorithms may be necessary at the center. The report also discusses the common development environment and software management issues. 13 refs.

The AL-SX/2 and AL-SX/3 are recently certified Type B shipping containers for tritium reservoirs. Both containers consist of an outer stainless steel drum overpack and sealed stainless steel containment vessel. WR reservoirs provide containment of tritium for normal conditions of transport. In accident conditions the containment vessel of the AL-SX must contain the tritium. A variety of reservoirs and materials will be packaged inside the containment vessel. These materials must not produce high pressure gas products that exceed the internal pressure capability of the vessel if the container is in an accident involving fire. This report summarizes outgassing tests performed on various organic materials. Tests of commonly used materials show that increased pressure due to outgassing is not a problem at elevated temperatures that simulate an accident. This report summarizes outgassing tests performed on various materials that may be packaged inside the AL-SX during shipment. These materials (except the getter) are normally a part of the reservoir shipping configuration. The objective of the tests was to determine the temperature that these materials begin to generate high pressure gaseous products.

During June and July 1991, the Sandia Transportable Lightning Instrumentation Facility (SATTLIF) was fielded at the Department of Defense (DoD) Security Operations Test Site (SOTS) at Ft. McClellan, Alabama. Nine negative cloud-to-ground lightning flashes were artifically triggered to designated locations on Igloo 2, a weapons storage bunker specially prepared to allow instrumentation access to various of its structural and electrical system elements. Simultaneous measurements of the incident flash currents and responses at 24 test points within the igloo and its grounding counterpoise network were recorded under lightning attachments to the front and rear air terminals of the structure`s lightning protection system. In Volume I the test is described in detail. The measured data are summarized and discussed. Appendix A contains the full set of recorded incident flash currents, while Appendix B presents the set of largest responses measured at each test point, for both front and rear attachments to the structure. As part of these tests, 0.050-in-thick stainless steel, 0.08-in copper, and 0.08-in titanium samples were exposed to triggered flash currents. In this way, damage spots created by direct-strike triggered lightning have been obtained, along with the measurement of the return-stroke and continuing currents that produced them. These data points, along with similar ones on aluminum and ferrous steel obtained during 1990 will be used as benchmarks against which to quantify the fidelity of burnthrough testing achievable Sandia`s advanced laboratory lightning simulator.

A channel ions can focus and guide a relativistic electron beam. This report discuses the generation of plasma channels using magnetically confined low energy electron beams in a low pressure gas. The most significant advantages of these channels are that any gas can be ionized and that they can easily be made to follow a curved path. The major advantages are that the channel is less well confined than a laser produced channel and that a small solenoidal magnetic field is required. This report is intended to be a guide for those technicians and scientists who need to assemble and operate an e-beam generated plasma channel system. Hardware requirements are discussed in detail. There are brief discussions of operating techniques, channel diagnostic, and channel characteristics.

This report contains viewgraphs on topics in the following areas: plasma facing components (PFC) operation in devices; disruption studies; laboratory PFM and high heat flux research; R&D for future machines; and neutron effects on thermonuclear materials.

Data are presented from the 18 W/m{sup 2} Mockup for Defense High-Level Waste, a very large scale in situ test fielded underground at the Waste Isolation Pilot Plant (WIPP). These data include selected fielding information, test configuration, instrumentation activities, and comprehensive results from a large number of gages. The results in this report give measured data from the thermal response gages, i.e., thermocouples, flux meters, and heater power gages emplaced in the test. Construction of the test began in June 1984; gage data in this report cover the complete test duration, that is, to June 1990.

The objective of this project is to apply Sandia`s expertise and technology towards the development of stimulation diagnostic technology in the areas of in situ stress, natural fracturing, stimulation processes and instrumentation systems. Initial work has concentrated on experiment planning for a site where hydraulic fracturing could be evaluated and design models and fracture diagnostics could be validated and improved. Important issues have been defined and new diagnostics, such as inclinometers, identified. In the area of in situ stress, circumferential velocity analysis is proving to be a useful diagnostic for stress orientation. Natural fracture studies of the Frontier formation are progressing; two fracture sets have been found and their relation to tectonic events have been hypothesized. Analyses of stimulation data have been performed for several sites, primarily for in situ stress information. Some new ideas in stimulation diagnostics have been proposed; these ideas may significantly improve fracture diagnostic capabilities.

The Nuclear Waste Repository Technology Department at Sandia National Laboratories (SNL) is investigating the suitability of Yucca Mountain as a potential site for underground burial of nuclear wastes. One element of the investigations is to assess the potential long-term effects of groundwater flow on the integrity of a potential repository. A number of computer codes are being used to model groundwater flow through geologic media in which the potential repository would be located. These codes compute numerical solutions for problems that are usually analytically intractable. Consequently, independent confirmation of the correctness of the solution is often not possible. Code verification is a process that permits the determination of the numerical accuracy of codes by comparing the results of several numerical solutions for the same problem. The international nuclear waste research community uses benchmarking for intercomparisons that partially satisfy the Nuclear Regulatory Commission (NRC) definition of code verification. This report presents the results from the COVE-2A (Code Verification) project, which is a subset of the COVE project.

The Yucca Mountain Site Characterization Project is studying Yucca Mountain in southwestern Nevada as a potential site for a high-level nuclear waste repository. Site characterization includes surface-based and underground testing. Analyses have been performed to design site characterization activities with minimal impact on the ability of the site to isolate waste, and on tests performed as part of the characterization process. One activity of site characterization is the construction of an Exploratory Studies Facility, which may include underground shafts, drifts, and ramps, and the accompanying ponds used for the storage of sewage water and muck water removed from construction operations. The information in this report pertains to the two-dimensional numerical calculations modelling the movement of sewage and settling pond water, and the potential effects of that water on repository performance and underground experiments. This document contains information that has been used in preparing Appendix I of the Exploratory Studies Facility Design Requirements document (ESF DR) for the Yucca Mountain Site Characterization Project.

The Yucca Mountain Site Characterization Project (YMP) is conducting studies to determine whether the Yucca Mountain site in southern Nevada will meet regulatory criteria for a potential mined geologic disposal system for high-level radioactive waste. Data gathered as part of these studies must be compiled and tabulated in a controlled manner for use in design and performance analyses. An integrated data management system has been developed to facilitate this process; this system relies on YMP participants to share in the development of the database and to ensure the integrity of the data. The site and Engineering Properties Database (SEPDB) is unique in that, unlike most databases where one data set is stored for use by one defined user, the SEPDB stores different sets of data which must be structured so that a variety of users can be given access to the information. All individuals responsible for activities supporting the license application should, to the extent possible,work with the same data and the same assumptions. For this reason, it is important that these data sets are readily accessible, comprehensive, and current. The SEPDB contains scientific and engineering data for use in performance assessment and design activities. These data sets currently consist of geologic, hydrologic, and rock properties information from drill holes and field measurements. The users of the SEPDB include engineers and scientists from several government research laboratories (Lawrence Livermore National Laboratory, Los Alamos National Laboratory, and Sandia National Laboratories), the US Geological Survey, and several government contractors. This manuscript describes the detailed requirements, contents, design, and status of the SEPDB, the procedures for submitting data to and/or requesting data from the SEPDB, and a SEPDB data dictionary (Appendix A) for defining the present contents.

Midway Valley, located at the eastern base of Yucca Mountain, Nye County, Nevada, has been identified as a possible location for the surface facilities of a potential high-level nuclear-waste repository. This structural and topographic valley is bounded by two north- trending, down-to-the-west normal faults: the Paintbrush Canyon fault on the east and the Bow Ridge fault on the west. Surface and near-surface geological data have been acquired from Midway Valley during the past three years with particular emphasis on evaluating the existence of Quaternary faults. A detailed (1:6000) surficial geological map has been prepared based on interpretation of new and existing aerial photographs, field mapping, soil pits, and trenches. No evidence was found that would indicate displacement of these surficial deposits along previously unrecognized faults. However, given the low rates of Quaternary faulting and the extensive areas that are covered by late Pleistocene to Holocene deposits south of Sever Wash, Quaternary faulting between known faults cannot be precluded based on surface evidence alone. Middle to late Pleistocene alluvial fan deposits (Unit Q3) exist at or near the surface throughout Midway Valley. Confidence is increased that the potential for surface fault rupture in Midway Valley can be assessed by excavations that expose the deposits and soils associated with Unit Q3 or older units (middle Pleistocene or earlier).

The US Department of Energy (DOE) has developed a site characterization plan (SCP) to collect detailed information on geology, geohydrology, geochemistry, geoengineering, hydrology, climate, and meteorology (collectively referred to as ``geologic information``) of the Yucca Mountain site. This information will be used to determine if a mined geologic disposal system (MGDS) capable of isolating high-level radioactive waste without adverse effects to public health and safety over 10,000 years, as required by regulations 40 CFR Part 191 and 10 CFR Part 60, could be constructed at the Yucca Mountain site. Forecasts of future climates conditions for the Yucca Mountain area will be based on both empirical and numerical techniques. The empirical modeling is based on the assumption that future climate change will follow past patterns. In this approach, paleclimate records will be analyzed to estimate the nature, timing, and probability of occurrence of certain climate states such as glacials and interglacials over the next 10,000 years. For a given state, key climate parameters such as precipitation and temperature will be assumed to be the same as determined from the paleoclimate data. The numerical approach, which is the primary focus of this paper, involves the numerical solution of basic equations associated with atmospheric motions. This paper describes these equations and the strategy for solving them to predict future climate conditions around Yucca Mountain.

The Strategic Defense Initiative Organization (SDIO) decided to investigate the possibility of launching a Russian Topaz 11 space nuclear power system. A preliminary safety assessment was conducted to determine whether or not a space mission could be conducted safely and within budget constraints. As part of this assessment, a safety policy and safety functional requirements were developed to guide both the safely assessment and future Topaz II activities. A review of the Russian flight safety program was conducted and documented. Our preliminary safety assessment included a top level event tree, neutronic analysis of normal and accident configurations, an evaluation of temperature coefficients of reactivity, a reentry and disposal analysis, and analysis of postulated launch abort impact accidents, and an analysis of postulated propellant fire and explosion accidents. Based on the assessment, it appears that it will be possible to safely launch the Topaz II system in the US with some possible system modifications. The principal system modifications will probably include design changes to preclude water flooded criticality and to assure intact reentry.

This paper presents an overview of the preclosure seismic hazards and the influence of these hazards on determining the suitability of Yucca Mountain as a national high-level nuclear-waste repository. Geologic data, engineering analyses, and regulatory guidelines must be examined collectively to assess this suitability. An environmental assessment for Yucca Mountain, written in 1986, compiled and evaluated the existing tectonic data and presented arguments to satisfy, in part, the regulatory requirements that must be met if the Yucca Mountain site is to become a national waste repository. Analyses have been performed in the past five years that better quantify the local seismic hazards and the possibility that these hazards could lead to release of radionuclides to the environment. The results from these analyses increase the confidence in the ability of Yucca Mountain and the facilities that may be built there to function satisfactorily in their role as a waste repository. Uncertainties remain, however, primarily in the input parameters and boundary conditions for the models that were used to complete the analyses. These models must be validated and uncertainties reduced before Yucca Mountain can qualify as a viable high-level nuclear waste repository.

The design of cementitious repository seals requires an understanding of cement hydration effects in developing a tight interface zone between the rock and the seal. For this paper, a computer code, SHAFT.SEAL, is used to model early-age cement hydration effects and performs thermal and thermomechanical analysis of cementitious seals. The model is described, and then used to analyze for the effects of seal size, rock temperature and placement temperature. The model results assist in selecting the instrumentation necessary for progressive evaluation of seal components and seal-system tests. Also, the results identify strategies for seal emplacement for a series of repository seal tests for the Yucca Mountain Site Characterization Project (YMP).

Many complex physical processes are modeled by coupled systems of partial differential equations (PDEs). Often, the numerical approximation of these PDEs requires the solution of large sparse nonsymmetric systems of equations. In this paper we compare the parallel performance of a number of preconditioned Krylov subspace methods on a large-scale MIMD machine. These methods are among the most robust and efficient iterative algorithms for the solution of large sparse linear systems. They are easy to implement on various architectures and work well on a wide variety of important problems. In this comparison we focus on the parallel issues associated with both local preconditioners (those that combine information from the entire domain). The various preconditioners are applied to a variety of PDE problems within the GMRES, CCGS, BiCGSTAB, and QMRCGS methods. Conclusions are drawn on the effectiveness of the different schemes based on results obtained from a 1024 processor a nCUBE 2 hypercube.

This paper describes the plan for a test to failure of a steel containment vessel model. The test specimen proposed for this test is a scale model representing certain features of an improved BWR MARK-2 containment vessel. The objective of this test is to investigate the ultimate structural behavior of the model by incrementally increasing the internal pressure, at ambient temperature, until failure occurs. Pre- and posttest analyses will be conducted to predict and evaluate the results of this test. The main objective of these analyses to validate, by comparisons with the experimental data, the analytical methods used to evaluate the structural behavior of an actual containment vessel under severe accident conditions. This experiment is part of a cooperative program between the Nuclear Power Engineering Corporation (NUPEC), the United States Nuclear Regulatory Commission (NRC), and Sandia National Laboratories (SNL).

Logging technologies developed hydrocarbon resource evaluation have not migrated into geothermal applications even though data so obtained would strengthen reservoir characterization efforts. Two causative issues have impeded progress: (i) there is a general lack of vetted, high-temperature instrumentation, and (ii) the interpretation of log data generated in a geothermal formation is in its infancy. Memory-logging tools provide a path around the first obstacle by providing quality data at a low cost. These tools feature on-board computers that process and store data, and newer systems may be programmed to make decisions.'' Since memory tools are completely self-contained, they are readily deployed using the slick line found on most drilling locations. They have proven to be rugged, and a minimum training program is required for operator personnel. Present tools measure properties such as temperature and pressure, and the development of noise, deviation, and fluid conductivity logs based on existing hardware is relatively easy. A more complex geochemical tool aimed at a quantitative analysis of potassium, uranium and thorium will be available in about on year, and it is expandable into all nuclear measurements common in the hydrocarbon industry. A second tool designed to sample fluids at conditions exceeding 400{degrees}C is in the proposal stage. Partnerships are being formed between the geothermal industry, scientific drilling programs, and the national laboratories to define and develop inversion algorithms relating raw tool data to more pertinent information. 8 refs.

The overpressurization of a 1:6 scale reinforced concrete containment building demonstrated that liner tearing is a plausible failure mode in such structures under severe accident conditions. A combined experimental and analytical program was developed to determine the important parameters that affect liner tearing and to develop reasonably simple analytical methods for predicting when tearing will occur. Three sets of test specimens were designed to allow individual control over and investigation of the mechanisms believed to be important in causing failure of the liner plate. The series of tests investigated the effect on liner tearing produced by the anchorage system, the loading conditions, and the transition in thickness of the liner. Before testing, the specimens were analyzed using two- and three-dimensional finite element models. Based on the analysis, the failure mode and corresponding load conditions were predicted for each specimen. Test data and posttest examination of test specimens shows mixed agreement with the analytical predictions with regard to failure mode and specimen response for most tests. Many similarities were also observed between the response of the liner in the 1:6 scale reinforced concrete containment model and the response of the test specimens. This work illustrates the fact that the failure mechanism of a reinforced concrete containment building can be greatly influenced by details of liner and anchorage system design. Furthermore, it significantly increases the understanding of containment building response under severe accident conditions.

Acoustic telemetry has been a dream of the drilling industry for the past 50 years. It offers the promise of data rates which are one-hundred times greater than existing technology. Such a system would open the door to true logging-while-drilling technology and bring enormous profits to its developers. The basic idea is to produce an encoded sound wave at the bottom of the well, let it propagate up the steel drillpipe, and extract the data from the signal at the surface. Unfortunately, substantial difficulties arise. The first difficult problem is to produce the sound wave. Since the most promising transmission wavelengths are about 20 feet, normal transducer efficiencies are quire low. Compounding this problem is the structural complexity of the bottomhole assembly and drillstring. For example, the acoustic impedance of the drillstring changes every 30 feet and produces an unusual scattering pattern in the acoustic transmission. This scattering pattern causes distortion of the signal and is often confused with signal attenuation. These problems are not intractable. Recent work has demonstrated that broad frequency bands exist which are capable of transmitting data at rates up to 100 bits per second. Our work has also identified the mechanism which is responsible for the observed anomalies in the patterns of signal attenuation. Furthermore in the past few years a body of experience has been developed in designing more efficient transducers for application to metal waveguides. The direction of future work is clear. New transducer designs which are more efficient and compatible with existing downhole power supplies need to be built and tested; existing field test data need to be analyzed for transmission bandwidth and attenuation; and the new and less expensive methods of collecting data on transmission path quality need to be incorporated into this effort. 11 refs.

Electronic excitations in adsorbate layers stimulate desorption and dissociation of adsorbed molecules as well as chemical reactions between adsorbates. The highest-probability stimulated processes produce neutral desorbates and determine how surface composition is altered by electron or photon radiation. A basic understanding has emerged, due largely to laser resonance-enhanced multi-photon ionization (REMPI) experiments, which provide quantum-state resolution of the gas-phase products. Auger phenomena enter this understanding in several ways. For example, CVV Auger spectroscopy determines the screened hole-hole interaction, U, in adsorbates, which in turn provides insight into the degree of charge-transfer screening from the substrate. In those systems where screening charge is used in excitation Auger decay, screening directly determines the lifetime, which in turn can exponentially affect the yield. Reductions in screening, e.g. induced by coadsorption of electro-negative species, thus can result in giant yield enhancements. As separate issues, a finite U may prevent the fast resonant decay and thus increase the yield from two-hole excitations, as has been suggested for NO2 dissociation on Pt(lll), or may assist in the localization (self-trapping) of two-hole excitations in dense adsorbate layers, as apparently is the case for NO desorption from the same surface. The latter causes the yields from one- and two-hole excitations to differ in their coverage dependence. Finally, CVV Auger spectroscopy, of course, measures the energies of two-hole excitations, which can be correlated with observed stimulated thresholds. © 1992 IOP Publishing Ltd.

The frequency response of the Faraday rotation in fiber current sensors is computed and measured for sensor coils of noncircular cross section and with displaced coil and conductor axes. Resonances are observed at higher frequencies with magnitudes approaching that of the low frequency response. Narrowband current sensors at frequencies above 100 MHz are reported.

An effort has been undertaken to develop a brittle fracture acceptance criterion for structural components of nuclear material transportation casks. The need for such a criterion was twofold. First, new generation cask designs have proposed the use of ferritic steels and other materials to replace the austenitic stainless steel commonly used for structural components in transport casks. Unlike austenitic stainless steel which fails in a high-energy absorbing, ductile tearing mode, it is possible for these candidate materials to fail via brittle fracture when subjected to certain combinations of elevated loading rates and low temperatures. Second, there is no established brittle fracture criterion accepted by the regulatory community that covers a broad range of structural materials. Although the existing IAEA Safety Series {number sign}37 addressed brittle fracture, its the guidance was dated and pertained only to ferritic steels. Consultant's Services Meetings held under the auspices of the IAEA have resulted in a recommended brittle fracture criterion. The brittle fracture criterion is based on linear elastic fracture mechanics, and is the result of a consensus of experts from six participating IAEA-member countries. The brittle fracture criterion allows three approaches to determine the fracture toughness of the structural material. The three approaches present the opportunity to balance material testing requirements and the conservatism of the material's fracture toughness which must be used to demonstrate resistance to brittle fracture. This work has resulted in a revised Appendix IX to Safety Series {number sign}37 which will be released as an IAEA Technical Document within the coming year.

As part of the design process for a hypersonic vehicle, it is necessary to predict the aerodynamic and aerothermodynamic environment for flight conditions. This involves combining results obtained from ground testing with analytical modeling to predict the aerodynamics and heating for all conditions of interest. The question which always arises is, how well will these models predict what is actually seen in a flight environment? This paper will briefly address ground-testing and analytical modeling and discuss where each is appropriate, and the associated problems with each area. It will then describe flight test options as well as instrumentation currently available and show how flight tests can be used to validate or improve models. Finally, several results will be shown to indicate areas where ground testing and modeling alone are inadequate to accurately predict hypersonic aerodynamics and aerothermodynamics.

We show experimentally and theoretically that the generation of the 13-TW Hermes III electron beam can be accurately monitored, and that the beam can be accurately directed onto a high-Z target to produce a wide variety of bremsstrahlung patterns. This control allows the study of radiation effects induced by gamma rays to be extended into new parameters regimes. Finally, we show that the beam can be stably transported in low-pressure gas cells.

This paper presents the groundwork for a completely automatic 3-D hexahedral mesh generation algorithm called plastering. It is an extension of the paving algorithm developed by Blacker, where paving is a completely automatic 2-D quadrilateral meshing technique.

The transport of a chemically reactive fluid through a permeable medium is governed by many classes of chemical interactions. Dissolution/precipitation (D/P) reactions are among the interactions of primary importance because of their significant influence on the mobility of aqueous ions. In general, D/P reactions lead to the propagation of coherent waves. This paper provides an overview of the types of wave phenomena observed in one-dimensional (1D) and two-dimensional (2D) porous media for systems in which mineral D/P is the dominant type of chemical reaction. It is demonstrated that minerals dissolve in sharp waves in 1D advection-dominated transport, and that these waves separate zones of constant chemical compositions in the aqueous and mineral phases. Analytical solutions based on coherence methods are presented for solving 1D advection-dominated transport problems with constant and variable boundary conditions. Numerical solutions of diffusion-dominated transport in porous media show that sharp D/P fronts occur in this system as well. A final example presents a simple dual-porosity system with advection in an idealized fracture and solute diffusion into an adjacent porous matrix. The example illustrates the delay of contaminant release from the 2D domain due to a combination of physical retardation and chemical retardation.

A closely coupled computational and experimental aerodynamics research program was conducted on a hypersonic vehicle configuration at Mach 8. Aerodynamic force and moment measurements and flow visualization results were obtained in the Sandia National Laboratories hypersonic wind tunnel for laminar boundary layer conditions. Parabolized and iterative Navier-Stokes simulations were used to predict flow fields and forces and moments on the hypersonic configuration. The basic vehicle configuration is a spherically blunted 10{degrees} cone with a slice parallel with the axis of the vehicle. On the slice portion of the vehicle, a flap can be attached so that deflection angles of 10{degrees}, 20{degrees}, and 30{degrees} can be obtained. Comparisons are made between experimental and computational results to evaluate quality of each and to identify areas where improvements are needed. This extensive set of high-quality experimental force and moment measurements is recommended for use in the calibration and validation of computational aerodynamics codes. 22 refs.

A theory for creeping flow of concentrated suspensions is described that takes into account the fluctuations of particles about their mean motion. The intensity of the velocity fluctuations is characterized by an internal field analogous to the temperature in classical kinetic theories, and governed by a balance law for the fluctuation energy. Explicit forms are posed for the viscosity, conductivity, dissipation, and pressure as functions of the temperature and mean interparticle separation. Approximate solutions are found for the temperature, separation, and mean velocity fields in flow between parallel plates. Qualitative behavior comparable to experimental observations is predicted: particle fluctuations and the mean shearing are confined to a region near the channel wall, while a plug-like region prevails in the center. © 1992 Elsevier B.V.

Microstructural models of deformation of polycrystalline materials suggest that inelastic deformation leads to the formation of a corner or vertex at the current load point. This vertex can cause the response to non-proportional loading to be more compliant than predicted by the smooth yield-surface idealization. Combined compression-torsion experiments on Tennessee marble indicate that a vertex forms during inelastic flow. An important implication is that strain localization by bifurcation occurs earlier than predicted by bifurcation analysis using isotropic hardening.

Acoustic emissions and conventional strain measurements were used to follow the evolution of ihc damage surface and plastic potential in a limestone under triaxial compression. Confining pressures were chosen such that macroscopically, the limestone exhibited both brittle and ductile behavior. The parameters derived are useful for modeling the deformation of a pressure-dependent material and for computing when localization would occur.

X-ray observations of boiling sodium in a 75-kW{sub t} reflux-pool-boiler solar receiver operating at up to 800{degrees}C were carried out. Both cinematographic and quantitative observations were made. From the cinematography, the pool free surface was observed before and during the start of boiling. During boiling, the free surface rose out of the field of view, and chaotic motion was observed. From the quantitative observations, void fraction in pencil-like probe volumes was inferred, using a linear array of detectors. Useful data were obtained from three of the eight probe volumes. Information from the other volumes was masked by scattered radiation. During boiling, time-averaged void fractions ranged from 0.6 to 0.8. During hot restarts, void fractions near unity occurred and persisted for up to {1/2} second. 17 refs.

Application of conventional fracture mechanics concepts to treat crack growth and failure problems in geological media is discussed in this paper. Conventional fracture mechanics methods were developed mainly for metallic materials which exhibit nonlinearity associated mainly with plasticity type responses. Thus, these are not directly applicable to geological materials whose inelastic responses originate from inherent large-scale heterogenities, microcracking, strain softening, etc. Proposed fracture mechanics methods for geological materials and their associated problems are discussed. To demonstrate the utility of fracture mechanics concepts in geological applications, examples involving multiple-fracture generation in tight gas formations and oil shale blasting design are presented.

Many robot control algorithms for high performance in-contact operations including hybrid force/position, stiffness control and impedance control approaches require the command of the joint torques. However, most commercially available robots do not provide joint torque command capabilities. The joint command at the user level is typically position or velocity and at the control developer level is voltage current, or pulse-width, and the torque generated is a nonlinear function of the command and joint position. To enable the application of high performance in-contact control algorithms to commercially available robots, and thereby facilitate technology transfer from the robot control research community to commercial applications, a practical methodology has been developed to linearize the torque characteristics of electric motor-amplifier combinations. A four degree-of-freedom Adept 2 robot, having pulse-width modulation amplifiers and both variable reluctance and brushless DC motors, is converted to operate from joint torque commands to demonstrate the methodology. The average percentage torque deviation over the command and position ranges is reduced from as much as 76% to below 5% for the direct-drive joints 1, 2 and 4 and is cut by one half in the remaining ball-screw driven joint 3. 16 refs., 16 figs., 2 tabs.

Light emission microscopy is now currently used in most integrated circuit (IC) failure analysis laboratories. This tutorial is designed to benefit both novice and experienced failure analysts by providing an introduction to light emission microscopy as well as information on new techniques, such as the use of spectral signatures. The use of light emission for accurate identification and spatial localization of physical defects and failure mechanisms is presented. This includes the analysis of defects such as short circuits which do not themselves emit light. The importance of understanding the particular IC design and applying the correct electrical stimulus is stressed. A video tape is used to show light emission from pn junctions, MOS transistors, test structures, and CMOS ICs in static and dynamic electrical stimulus conditions. 27 refs.

Bent-axis maneuvering vehicles provide a unique type of control for a variety of supersonic and hypersonic missions. Unfortunately, large hinge moments, incomplete pitching moment predictions, and a misunderstanding of corresponding center of pressure calculations have prevented their application. A procedure is presented for the efficient design of bent-axis vehicles given an adequate understanding of origins of pitching moment effects. In particular,sources of pitching moment contributions will be described including not only normal force, but inviscid axial force and viscous effects as well. Off-centerline center of pressure effects are first reviewed for symmetric hypersonic sphere-cone configurations. Next the effects of the bent-axis geometry are considered where axial force, acting on the deflected tail section, can generate significant pitching moment components. The unique relationship between hinge moments and pitching moments for the bent-axis class of vehicles is discussed. 15 refs.

The scanning electron microscope (SEM) has become as standard a tool for IC failure analysis as the optical microscope, with improvements in existing SEM techniques and new techniques being reported regularly. This tutorial has been designed to benefit both novice and experienced failure analysts by reviewing several standard as well as new SEM techniques used for failure analysis. Advanced electron-beam test systems will be covered briefly; however all techniques discussed may be performed on any standard SEM. Topics to be covered are (1) standard techniques: secondary electron imaging for surface topology, voltage contrast, capacitive coupling voltage contrast, backscattered electron imaging, electron beam induced current imaging, and x-ray microanalysis and (2) new SEM techniques: novel voltage contrast applications, resistive contrast imaging, biased resistive contrast imaging, and charge-induced voltage alteration. Each technique will be described in terms of the information yielded, the physics behind technique use, any special equipment and/or instrumentation required to implement the technique, the expertise required to implement the technique, possible damage to the IC as a result of using the technique, and examples of using the technique for failure analysis. 11 refs.

Technologies that use carbon and mixed metal oxides as the electrode material have been pursued for the purpose of producing high-reliability double-layer capacitors (DLCs). The author demonstrates their environmental stability in temperature, shock, vibration, and linear acceleration. She reviews the available test data for both types of DLCs under these stress conditions. This study suggests that mixed metal oxides and carbon-based double-layer capacitors can survive robust environments if packaged properly, and that temperature decreases performance of double-layer capacitors.

We have obtained dual-longitudinal-mode operation of a Q-switched Nd:YAG laser by simultaneous injection-seeding at two frequencies to produce pulses with modulation frequency discretely tunable from 185 MHz to greater than 17 GHz.

The Thermionic System Evaluation Test (TSET) is a ground test of an unfueled Russian TOPAZ-II in-core thermionic space reactor powered by electric heaters. The facility that will be used for testing of the TOPAZ-II systems is located at the New Mexico Engineering Research Institute (NMERI) complex in Albuquerque, NM. The reassembly of the Russian test equipment is the responsibility of International Scientific Products (ISP), a San Jose, CA, company and Inertek, a Russian corporation, with support provided by engineers and technicians from Phillips Laboratory (PL), Sandia National Laboratories (SNL), Los Alamos National Laboratory (LANL), and the University of New Mexico (UNM). This test is the first test to be performed under the New Mexico Strategic Alliance agreement. This alliance consist of the PL, SNL, LANL, and UNM. The testing is being funded by the Strategic Defense Initiative Organization (SDIO) with the PL responsible for project execution.

A revised nomenclature for defects in MOS devices is described which clearly distinguishes the language used to describe the physical location of defects from that used to describe their electrical response. ''Oxide traps'' are simply defects in the SiO{sub 2} layer, and ''interface traps'' are defects at the Si/SiO{sub 2} interface; nothing is presumed about how either communicates with the underlying Si. ''Fixed states'' are defined electrically as trap levels that do not communicate with the Si on the time scale, but ''switching states'' can exchange charge with the Si. Fixed states presumably are oxide traps, but switching states can either be interface traps or near-interfacial oxide traps that can communicate with the Si, i.e. ''border traps.'' Thus the term ''traps'' is reserved for defect location, and the term ''states'' for electrical response. This defect picture is used to provide new insight into the response of MOS capacitors with 45-nm radiation-hardened oxides to electrical stress and annealing; capacitance-voltage and thermally-stimulated-current measurements are used. 2 figs, 14 refs. (DLC)

Radioactive material transport casks use either lead or depleted uranium (DU) as gamma-ray shielding material. Stainless steel is conventionally used for structural containment. If a DU alloy had sufficient properties to guarantee resistance to failure during both nominal use and accident conditions to serve the dual-role of shielding and containment, the use of other structure materials (i.e., stainless steel) could be reduced. (It is recognized that lead can play no structural role.) Significant reductions in cask weight and dimensions could then be achieved perhaps allowing an increase in payload. The mechanical response of depleted uranium has previously not been included in calculations intended to show that DU-shielded transport casks will maintain their containment function during all conditions. This paper describesa two-part study of depleted uranium alloys: First, the mechanical behavior of DU alloys was determined in order to extend the limited set of mechanical properties reported in the literature. The mechanical properties measured include the tensile behavior the impact energy. Fracture toughness testing was also performed to determine the sensitivity of DU alloys to brittle fracture. Fracture toughness is the inherent material property which quantifies the fracmm resistance of a material. Tensile strength and ductility are significant in terms of other failure modes, however, as win be discussed. These mechanical properties were then input into finite element calculations of cask response to loading conditions to quantify the potential for claiming structural credit for DU. (The term structural credit'' describes whether a material has adequate properties to allow it to assume a positive role in withstanding structural loadings.)

The solution of ER/WM problems will rely on the use of expert judgments. These judgments should be able to withstand the same rigorous scrutiny as the decisions made to solve these problems. Therefore, those judgments that are likely to have a significant impact on the solution of ER/WM problems should be elicited and used in a formal manner. In this paper, we discuss the key areas of environmental management where expert judgments are expected to be crucial, as well as the process to formalize them. This process is a generic one and should only be construed as a roadmap; specific aspects of the process need to be tailored to address the problem at hand. By employing this process, the quality of the judgments is enhanced, and therefore, the likelihood that the solution of ER/WM problems will be a sound and defensible one is considerably increased.

Several different techniques are used to electrically characterize defects at or near the Si/SiO{sub 2} interface. Three common methods are the charge-pumping, midgap, and dual-transistor techniques. Each of these techniques offer advantages and disadvantages compared to the others. For instance, charge-pumping measurements are not significantly affected by charge lateral non-uniformities and can provide high-sensitivity measurements of the average density of interface traps. However, charge-pumping measurements cannot provide accurate measurements of the number of charged oxide traps. In contrast both the dual-tranistor and midgap techniques can provide good estimates for threshold-voltage shifts due to oxide traps and interface traps, but these estimates can break down when significant charge lateral non-uniformities are present in the oxide. Considering the widespread use of these, techniques, it is of practical and theoretical importance to quantitatively compare them. At the SISC, we will present a detailed comparison of the charge-pumping, midgap, and dual-tranistor techniques. Values for the density of interface traps measured using the three techniques will be compared for n- and P-channel transistors fabricated using several different process technologies, and under different process technologies, and under different irradiation and anneal conditions. Discrepancies between the different techniques are observed. Causes for the discrepancies will be explored at the SISC.

Environmental management involves making decisions that will lead to the solution of environmental restoration and waste management (ER/WM) problems. Not only are ER/WM problems technologically challenging, but they must be dealt with under politically and emotionally charged conditions. Furthermore, these decisions must be made based on less than certain information. Therefore, environmental managers must consider the sources of uncertainty that will impact the results of the decision-making process, treat them in an explicit manner, and assess their impact on the decision. Consequently, the process must be a defensible, objective, and transparent one; otherwise the foundation for solving ER/WM problems will not be sufficiently solid to survive the criticisms that such solutions are likely to be subjected to. The use of risk assessment and decision analysis tools helps the environmental manager achieve this goal. It is also important that these decisions consider the array of risk-related issues associated with ER/WM problems, which include the risk to the health and safety of the public as well as other risks such as economic risk. The solution of ER/WM problems must obtain and maintain a proper balance between all these issues. It is also crucial that the multiple stakeholders having an interest in the solution of ER/WM problems be involved in the decision-making process.

We discuss the use of light scattered from a latent image to control photoresist exposure dose and focus conditions which results in improved control of the critical dimension (CD) of the developed photoresist. A laser at a non-exposing wavelength is used to illuminate a latent image grating. The light diffracted from the grating is directly related to the exposure dose and focus and thus to the resultant CD in the developed resist. Modeling has been done using rigorous coupled wave analysis to predict the diffraction from a latent image as a function of the substrate optical properties and the photoactive compound (PAC) concentration distribution inside the photoresist. It is possible to use the model to solve the inverse problem: given the diffraction, to predict the parameters of the latent image and hence the developed pattern. This latent image monitor can be implemented in a stepper to monitor exposure in situ, or prior to development to predict the developed CD of a wafer for early detection of bad devices. Experimentation has been conducted using various photoresists and substrates with excellent agreement between theoretical and experimental results. The technique has been used to characterize a test pattern with a focused spot as small as 36{mu}m in diameter. Using diffracted light from a simulated closed-loop control of exposure dose, CD control was improved by as much as 4 times for substrates with variations in underlying film thickness, compared to using fixed exposure time. The latent image monitor has also been applied to wafers with rough metal substrates and focus optimization.

A brief overview of selected programs at Sandia is presented. This issue contains high-lights on the following: Reducing risk in nuclear reactors; energy and environment news in brief; eliminating bottlenecks in plastics recycling; new technologies remedy old waste problems; new technologies remedy old waste problems; safe disposal of military components; and heat pipes for stirling engine testing.

Sandia National Laboratories has, for several years, been engaged in the performance of both fire safety and electrical equipment qualification research under independent programs sponsored by the US Nuclear Regulatory Commission. Recent comparisons between electrical cable thermal damageability data gathered independently in these two efforts indicate that a direct correlation exists between certain of the recent cable thermal vulnerability information gathered under equipment qualification conditions and thermal damageability in a fire environment. This direct correlation allows for a significant expansion of the data base on estimated cable thermal vulnerability limits in a fire environment because of the wide range of cable types and products that have been evaluated as a part of the equipment qualification research. This paper provides a discussion of the basis for the derived correlation, and presents estimated cable thermal damage limits for a wide range of generic cable types and specific cable products. The supposition that a direct correlation exists is supported through direct comparisons of the test results for certain specific cable products. The proposed supplemental cable fire vulnerability data gained from examination of the equipment qualification results is presented. These results should be of particular interest to those engaged in the evaluation of fire risk for industrial facilities, including nuclear power plants.

C++ is rapidly gaining in popularity as a scientific programming language. The data encapsulation inherent in the class concept and the availability of operator overloading for compact representation of operations make it an ideal language for translating concepts in mathematical physics into computer code. Furthermore, its strong type checking and memory management features facilitate correct coding of algorithms. Unfortunately, C++ code which is written in the true spirit of the language is often very inefficient under current compiler implementations. Many of the inefficiency issues, such as unnecessary copy operations or proliferation of temporaries, have been well-characterized. Some may be alleviated by clever C++ coding, but others cannot be alleviated except by writing C-like code that sacrifices one or more of the best features of the language. This document describes a major source of efficiency problems in expressions using overloaded operators on array classes, and proposes certain minor modifications to the C++ language standard which will facilitate optimization of these expressions.

Sandia and Mound are developing a workcell that will automate the assembly of explosive components. Sandia is responsible for the automated powder dispenser subsystem. Automated dispensing of explosive powders in the past resulted in separation or segregation of powder constituents. The Automated Dry Powder Dispenser designed by Sandia achieves weight tolerances of {plus minus}0.1 mg while keeping powderoxidizer separation to a minimum. A software control algorithm compensates fore changes in powder flow due to lot variations, temperature, humidity, and the amount of powder left in the system.

Interfacial microchemical characterization is required in all aspects of surface processing as applied to transportation and utility technologies. Corrosion protection, fuel cells and batteries, wear surfaces, polymers and polymer-oxide interfaces, thin film multilayers, photoelectrochemical systems, and organized molecular assemblies are just a few examples of interfacial systems of interest to these industries. A number of materials and processing problems, both related to fundamental understanding and to monitoring manufacturing operations, have been identified where our microchemical characterization abilities need improving. Over twenty areas for research are identified where progress will contribute to improved understanding of materials and processes, improved problem-solving abilities, improved manufacturing consistency, and lower costs. Some of the highest priority areas for research include (1) developing techniques and methods with improved chemical specificity at interfaces, (2) developing fast, real-time surface and interface probes and (3) improving the cost and reliability of manufacturing monitors. Increased collaboration among University, Industry, and Government laboratories will be a prerequisite to making the required progress in a timely fashion.

This paper describes the application of linear control design techniques to the problem of nuclear reactor control. The control algorithm consists of generating a nominal trajectory within the control authority of the reactor rod drives, and then following this trajectory with a gain scheduled linear quadratic regulator (LQR). A controller based on this algorithm has generated power pulses up to 100 MW on Sandia's Annular Core Research Reactor (ACRR). Prompt critical control at $1.02 net reactivity and controlled start up rates over 350 DPM have also been demonstrated using tills controller.

There is a discrepancy between literature estimates of trapped-hole energies in irradiated SiO{sub 2} obtained via thermal and optical methods (0.6-1.4 eV and 3 eV, respectively). A method has been developed for obtaining an improved estimate of the energy distribution of trapped holes in irradiated SiO{sub 2}, which brings thermal and optical estimates into much closer agreement. Experimental and theoretical TSC (thermally stimulated current) spectra are shown for a soft MOS capacitor with a 350-nm oxide cycled through 4 irradiations (10 keV x rays) and TSC measurements. Four trap-energy distributions were also independently derived from TSC at different ramp rates for a 45-nm radiation-hardened oxide. The trap distributions inferred from TSC for the 45-nm hard oxide agree with each other and with that inferred for the soft 350-nm oxide. 2 figs, 8 refs. (DLC)

International Atomic Energy Agency (IAEA) inspectors must maintain continuity of knowledge on all safeguard samples, and in particular on those samples drawn from plutonium product and spent fuel input tanks at a nuclear reprocessing plant's blister sampling station. Integrity of safeguard samples must be guaranteed from the sampling point to the moment of sample analysis at the IAEA's Safeguards Analytical Laboratory (SAL Seibersdorf) or at an accepted local laboratory. These safeguard samples are drawn at a blister sampling station with inspector participation, and then transferred via a pneumatic post system to the facility's analytical laboratory. The transfer of the sample by the pneumatic post system, the arrival of the sample in the operator's analytical laboratory, and the storage of the sample awaiting analysis is very time consuming for the inspector, particularly if continuous human surveillance is required for all these activities. This process might be observed by ordinary surveillance methods, such as a video monitoring system, but again this would be cumbersome and time consuming for both the inspector and operator. This paper will describe a secure container designed to assure sample vial integrity from the point the sample is drawn to the treatment of the sample at the facility's analytical laboratory.

The use of fine-particle size (<40 nm) unsupported catalysts in the solubilization step of direct coal liquefaction may result in improved economics for direct coal liquefaction due to the possible enhanced yields of desired products, the potential for decreasing reaction severity, and the possibility of using less supported catalyst during liquefaction processing. To guide the research and development efforts for these new unsupported catalysts, it is necessary to evaluate the catalyst performance under standard test conditions so that the impacts of catalyst formulations from different laboratories can be compared. The objectives of this work are to develop standard coal liquefaction test procedures and to perform the testing of the novel fine-particle size liquefaction catalysts being developed in the DOE/PETC AR Coal Liquefaction program. As part of this effort, we have developed a factorial experimental design to enable evaluation of the catalysts over ranges of temperature, time, and catalyst loading. The standard test procedure uses DECS-17 Blind Canyon Coal and 9,10-dihydrophenanthrene (DHP) as the hydrogen donor. Product analyses include tetrahydrofuran (THF) conversion, heptane conversion, DHP recovery, and gas analyses. THF and heptane insoluble materials are analyzed for carbon, hydrogen, nitrogen and sulfur contents. Testing is performed in batch microautoclave reactors. The experimental design and test procedures are being evaluated using {minus}100 mesh pyrite as a catalyst.

Understanding the mechanisms of growth during vapor-phase deposition is critical for the precise control of surface morphology required by advanced electronic device structures. Yet only relatively recently have the tools for observing this growth on an atomic-level scale become available (via scanning tunneling microscopy (STM), reflection high energy electron diffraction (RHEED) and low-energy electron microscopy (LEEM)). We present results from our own RHEED and STM measurements in which we use computer simulations to aid in determining the fundamental surface processes which contribute to.the observed structures. In this study of low-energy ion bombardment and growth on Si(001), it is demonstrated how simulations enable us to determine the dominant atomistic process.

This report highlights the following topics: Photon Correlation Spectroscopy--a new application in jet fuel analysis, Testing news in brief; Solar test facility supports space station research; Shock isolation technique developed for piezoresistive accelerometer; High-speed photography captures Distant Image measurements; and, Radiation effects test revised for CMOS electronics.

Reflective Particle Tags were developed for uniquely identifying individual strategic weapons that would be counted in order to verify arms control treaties. These tags were designed to be secure from copying and transfer even after being lift under the control of a very determined adversary for a number of years. This paper discusses how this technology can be applied in other applications requiring confidence that a piece of equipment, such as a seal or a component of a secure, has not been replaced with a similar item. The hardware and software needed to implement this technology is discussed, and guidelines for the sign of systems that rely on these or similar randomly formed features for security applications are presented. Substitution of identical components is one of the easiest ways to defeat security seals, secure containers, verification instrumentation, and similar equipment. This technology, when properly applied, provides a method to counter this defeat scenario. This paper presents a method for uniquely identifying critical security related equipment. Guidelines for implementing identification systems based on reflective particles or similar random features without compromising their intrinsic security are discussed.

In 1991, Sandia National Laboratories acquired a Network Storage Service (NSS) as a result of a fully competitive procurement. The Network Storage Service, which provides access to over a terabyte of data storage in a two-tiered hierarchy, had minimal software security features. Before the NSS could be placed into production, it had to be accredited by the Department of Energy, Sandia's accrediting authority. Sandia was faced with implementing security features to allow the NSS to be operated in its secure computing network, which is a single security clearance, multiple data security level environment. This paper describes the software security design alternatives that were considered and what was ultimately implemented.

The time dependence of radiation-induced interface-trap charge buildup for MOS transistors of varying gate-oxide thickness was investigated in order to clarify how the location of hydrogen in the SiO{sub 2} contributes to N{sub it} buildup. Radiation-induced interface-trap buildup in wet and dry gate oxides is compared for irradiations and anneals at constant positive bias and for negative-bias irradiations followed by positive-bias anneals. Implications of these results for different models of interface-trap buildup are discussed. 2 figs, 9 refs. (DLC)

A non-contact, high-resolution laser ranging device has been incorporated into an instrument for accurately mapping the surface of WECS airfoils in the field. Preliminary scans of composite materials and bug debris show that the system has adequate resolution to accurately map bug debris and other surface contamination. This system, just recently delivered and now being debugged and optimized, will be used to characterize blade surface contamination on wind turbines. The technology used in this system appears to hold promise for application to many other measurements tasks, including a system for quickly and very accurately determining the profile of turbine blade molds and blades.

Short communication.

Sandia National Laboratories has completed the design and is now fabricating packages for shipment of tritium gas in conformance with 10 CFR 71. The package, referred to as the AL-SX, is quite unique in that its contents are a radioactive gas, and a large margin of safety has been demonstrated through overtesting. The AL-SX is small, 42 cm in diameter and 55 cm tall, and weighs between 55 kg empty and up to a maximum of 60 kg with contents and is designed for a 20-year service life. This paper describes the design of the AL-SX and certification testing performed on AL-SX packages and discusses containment of tritium and AL-SX manufacturing considerations.

In this study, a discrete element technique was used to simulate drop breakup in two dimensions. A series of simulations in which the drop breakup occurred in the presence of a flow field was performed. The density ratio of the flow field to the drop in the simulations was comparable to many of the isothermal liquid/liquid drop breakup experiments performed to investigate hydrodynamic breakup during Fuel Coolant Interactions (FCIs). The randomly directed internal kinetic energy of the drop increased rapidly at the beginning of the interaction between the drop and the flow field due to momentum transfer from the flow field to the drop. After the initial increase in internal energy of the drop, the momentum transferred from the flow field to the drop in the form of translational kinetic energy of the center of mass of the drop. It was also observed that the drops simulated in the presence of a flow field required higher internal kinetic energies to fragment than did the drops observed in the simulations performed in the absence of a flow field.

Sandia National Laboratories is one of the nation's largest research and development (R and D) facilities and is responsible for national security programs in defense and energy with a primary emphasis on nuclear weapon R and D. However, Sandia also supports a wide variety of projects ranging from basic materials research to the design of specialized parachutes. As a multiprogram national laboratory, Sandia has much to offer both industrial and government customers in pursuing space nuclear technologies. A brief summary of Sandia's technical capabilities, test facilities, and example programs that relate to military and civilian objectives in space is presented.

Sandia National Laboratories is actively involved in testing coated particle nuclear fuels for the Space Nuclear Thermal Propulsion (SNTP) program managed by Phillips Laboratory. The testing program integrates the results of numerous in-pile and out-of-pile tests with modeling efforts to qualify fuel and fuel elements for the SNTP program. This paper briefly describes the capabilities of the Annular Core Research Reactor (in which the experiments are performed), the major in-pile tests, and the models used to determine the performance characteristics of the fuel and fuel elements. 6 refs.

The US Department of Energy's Slant Hole Completion Test Well, SHCT-1, was drilled in 1990 into gas-bearing, lenticular and blanket-shaped sandstones of the Mesaverde Formation, northwestern Colorado. The reservoirs are over-pressured, with sub-microdarcy, in situ, matrix-rock permeabilities. However, a set of sub-parallel natural fractures increases the whole-reservoir permeabilities, measured by well tests, to several tens of microdarcies. The slant hole azimuth was therefore oriented to cut across the dominant fracture strike, in order to access the natural-fracture permeability and increase drainage into the wellbore.

The intense radiation fields generated with useful uniformity over large volumes, using the novel compound-lens diode on Hermes III, are characterized. The measurements show that by changing the diode parameters, the peak dose, useful area, and useful volume of irradiation can be varied from ~100 krad(Si), ~600 cm2, and ~20×103 cm3 to 20 krad(Si), ~3400 cm2, and ~200×103 cm3, in a 19±2 ns radiation pulse. This versatility enables radiation fields to be tailored to a specified exposure requirement, significantly enhancing the capability of Hermes III to test radiation effects in systems. © 1992 IEEE

The well known Boltzmann-Matano analysis'' can be used in general to measure the diffusivity of binary and ternary alloys. However for alloys containing four or more components, the analysis requires making assumptions, for example that the diffusivity is constant. Conversely, it can be shown that the square root diffusivity analysis'' applies to measuring diffusivities that vary with concentration, as long as the variation is linear with concentration. Methods of designing samples and evaluating data for the square root diffusivity analysis are discussed.

A monolithic dose-rate nuclear event detector (NED) has been evaluated as a function of radiation pulse width. The dose-rate trip level of the NED was evaluated in "near" minimum and maximum sensitivity configurations for pulse widths from 20 to 250 ns and at dose rates from 106 to 109 rads(Si)/s. The trip level varied up to a factor of ∼16 with pulse width. At each pulse width the trip level can be varied intentionally by adding external resistors. Neutron irradiations caused an increase in the trip level, while electron irradiations, up to a total-dose of 50 krads(Si), had no measurable effect. This adjustable dose-rate-level detector should prove valuable to designers of radiation-hardened systems.

To assess the current capability for solving non-gray, anisotropically scattering multidimensional radiation problems, a specific problem was formulated for several participating authors to solve. They each applied their own methods to solve the problem, which was relevant to the modeling of heat transfer in coal-fired furnaces. This paper is a summary of the comparison of the results. Areas where future modeling efforts should address are identified.

The bonding configurations for simple phosphate glasses are quantitatively described by both the relative concentrations of different polyhedral phosphate sites (i.e., the Q{sup n} description) determined by {sup 31}p magic angle spinning nuclear magnetic resonance (MAS NMR) spectroscopy and by the relative concentrations of bridging and nonbridging oxygen as measured by x-ray photoelectron spectroscopy (XPS). Both spectroscopies illustrate the depolymerizing effects of modifier additions in two series of Na{sub 2}O and ZnO-P{sub 2}0{sub 5} glasses.

A robotic rover vehicle designed for use in the exploration of the Lunar surface is described. The Robotic All-Terrain Lunar Exploration Rover (R.A.T.L.E.R.) is a four wheeled all-wheel-drive dual-body vehicle. A uniquely simple method of chassis articulation is employed which allows all four wheels to remain in contact with the ground, even while climbing over step-like obstacles as large as 1.3 wheel diameters. Skid steering and modular construction are used to produce a simple, rugged, highly agile mobility chassis with a reduction in the number of parts required when compared to current designs being considered for planetary exploration missions. The design configuration, mobility parameters, and performance of several existing R.A.T.L.E.R. prototypes are discussed.

Particulate contamination during IC fabrication is generally acknowledged as a major contributor to yield loss. In particular, plasma processes have the potential for generating copious quantities of process induced particulates. Ideally, in order to effectively control process generated particulate contamination, a fundamental understanding of the particulate generation and transport is essential. Although a considerable amount of effort has been expended to study particles in laboratory apparatus, only a limited amount of work has been performed in production line equipment with production processes. In these experiments, a Drytek Quad Model 480 single wafer etcher was used to etch blanket thermal SiO{sub 2} films on 150 mm substrates in fluorocarbon discharges. The effects of rf power, reactor pressure, and feed gas composition on particle production rates were evaluated. Particles were measured using an HYT downstream particle flux monitor. Surface particle deposition was measured using a Tencor Surfscan 4500, as well as advanced ex situ techniques. Particle morphology and composition were also determined ex situ. Response surface methodology was utilized to determine the process conditions under which particle generation was most pronounced. The use of in situ and ex situ techniques has provided some insight into the mechanisms involved for particle generation and particle dynamics within the plasma during oxide etching.

Nitronic 60 is a nitrogen-strengthened austenitic stainless steel used for applications where metal-to-metal wear and galling resistance are required. In addition, it does not transfer to martensite with strain or upon cooling to cryogenic temperatures. In comparison to type 304 stainless steel, the nickel content is similar, chromium content is slightly reduced and manganese, silicon, and nitrogen are all increased in Nitronic 60. Although studies have shown that it can be joined with arc welding, it fabrication weldability is limited by heat-affected zone (HAZ) cracking. This study examined the HAZ cracking behavior of this alloy during autogenous gas tungsten arc welding and pulsed autogenous Nd:YAG welding.

The conclusions of the vulnerability test on VOPAN (verification of Operator's Analysis) as conducted at Safeguards Analytical Laboratory (ASA) at Seibersdorf, Austria in October 1990 and documented in STR-266, indicate that whenever samples are taken for safeguards purposes extreme care must be taken to ensure that they have not been interfered with during the sample taking, transportation, storage or sample preparation process.'' Indeed there exist a number of possibilities to alter the content of a safeguards sample vial from the moment of sampling up to the arrival of the treated (or untreated) sample at SAL. The time lapse between these two events can range from a few days up to months. The sample history over this period can be subdivided into three main sub-periods: (1) the period from when the sampling activities are commenced up to the treatment in the operator's laboratory, (2) during treatment of samples in the operator's laboratory, and finally, (3) the period between that treatment and the arrival of the sample at SAL. A combined effort between the Agency and the United States Support Program to the Agency (POTAS) has resulted in two active tasks and one proposed task to investigate improving the maintenance of continuity of knowledge on safeguards samples during the entire period of their existence. This paper describes the use of the Sample Vial Secure Container (SVSC), of the Authenticated Secure Container System (ASCS), and of the Secure Container for Storage and Transportation of samples (SCST) to guarantee that a representative portion of the solution sample will be received at SAL.

Three methods of evaluating accelerated battery test data are described. Criteria for each method are used to determine the minimum test matrix required for accurate predictions. Other test methods involving high current discharge and real time techniques are discussed.

Neutron spin-echo spectroscopy is used to study the topology of aerogels. Topology or connectivity is varied through precursor chemistry and thermal annealing. Topology is characterized using the concept of fractons (the vibrational excitations of a fractal network). A qualitative difference is observed in the spectrum of polymeric vs. colloidal aerogels, the latter showing a peak in the density of vibrational states. For colloidal aerogels whose structure appears to arise from phase separation in the solution precursor, low-energy excitations were only observed in the lowest density material studied. Finally, a transition from fractal to colloidal microstructure was observed during the sintering of polymeric aerogels. This transformation revealed itself as a transition from a fracton-like to a peaked density of states function. © 1992 Elsevier Science Publishers B.V. All rights reserved.

This document presents recent accomplishments in engineering and science at Sandia National Laboratories. Commercial-scale parabolic troughs at the National Solar Thermal Test Facility are used for such applications as heating water, producing steam for industrial processes, and driving absorption air conditioning systems. Computerized-aided design, superconductor technology, radar imaging, soldering technology, software development breakthroughs are made known. Defense programs are exhibited. And microchip engineering applications in test chips, flow sensors, miniature computers, integrated circuits, and microsensors are presented.

This paper describes experiments on the wettability of tin on oxygen free, high conductivity (OFHC) copper using a ″point source″ ultrasonic horn. Ultrasonics are used on such metals as aluminum or stainless steel which are difficult to wet without the use of very strong corrosives. These experiments explore the behavior of acoustic energy transmission in the horn-solder-substrate systems indicated by the solder film generated and explore the use of ultrasonics in actual electronic systems component fabrication and assembly processes.

An evaluation of substitutes for tin-lead alloy solders is discribed. The first part of the evaluation studies the wettability of tin-based, lead free solders. The second part evaluates the solderability. The solders evaluated were commercially available.

We present calculations which show the radial dependence of the KVV and L12VV Auger matrix elements of silicon. We find greatly differing dependences, converging within ~ 1 a.u. of the nucleus in the case of the KVV, but not until — 4 a.u. in the case of the L23VV, well beyond the bond midpoint of — 2.2 a.u. We also find quite different dependences for the various elements within a particular CVV transition. Because the local density of states (LDOS) is dependent on the radius of the sphere of integration, our results suggest that different CVV Auger processes on the same atom in fact probe different LDOSs, as do even different contributions within the same transition. (This effect is separate from the well-known matrix element property which weights angular-momentum components differently.) These results call into question both the single-site LDOS approximation when used in the interpretation of low-energy ( < 100 eV) Auger spectra, and the application to high-energy spectra of local densities of states obtained by integration over muffin-tin or Wigner-Seitz spheres which have a large radius compared to the region probed by the Auger process. © 1992, American Vacuum Society. All rights reserved.

This paper presents the results of a set of structural analyses performed to investigate the effects of internal gas generation on the extension of pre-existing fractures around disposal rooms at the Waste Isolation Pilot Plant. The response of a room and its contents is computed for this scenario to establish the condition of the room at any point in time. The development of the capability to perform these analyses represents an additional step in the development of an overall model for the disposal room.

Acid vapors have been used to fluxlessly reduce metal oxides and enhance wetting of solder on metallizations. Dilute solutions of hydrogen, acetic acid and formic acid in an inert carrier gas of nitrogen or argon were used with the sessile drop technique for 60Sn-40Pb solder on Cu and Au/Ni metallizations. The time to reduce metal oxides and degree of wetting as a function of acid vapor concentration were characterized. Acetic and formic acids reduce the surface metal oxides sufficiently to form metallurgically sound solder joints. Hydrogen did not reduce oxides rapidly enough at 220°C to be suitable for soldering applications. The optimum conditions for oxide reduction with formic acid was with an acid vapor concentration in nitrogen carrier gas of 4% for Cu metallizations and 1.6% on Au/Ni. The acetic acid vapor concentration, also in nitrogen, was optimized at 1.5% for both metallizations. Above a vapor concentration of 1.5%, the acetic acid combined with the bare metal to form acetates which increased the wetting time. These results indicate that acid vapor fluxless soldering is a viable alternative to traditional flux soldering.

The measurement of surface pressures on a body which is submerged in flowing water involves several problems which are not encountered when the test medium is air. Many of these problems exist even if the water velocity is low, and become more severe at higher velocitics (45-65 ft/sec) where the surface pressure may be low enough for cavitation to occur. Problem areas which are discussed include:hydrostatic pressure, surface tension, orifice errors, thermal effects on surface-mounted transducers, electrical fields, two-phase phenomena and air content.

Nuclear weapons system designers and safety analysts are contemplating broader use of probabilistic risk assessment techniques. As an aid to their understanding, this document summarizes the development and use of probabilistic risk assessment (PRA) techniques in the nuclear power industry. This report emphasizes the use of PRA in decision making with the use of case studies. Nuclear weapon system designers and safety analysts, contemplating the broader use of PRA techniques, will find this document useful.

This document contains implementation details for the Quality Information Management System (QIMS) Pilot Project, which has been released for VAX/VMS systems using the INGRES RDBMS. The INGRES Applications-By-Forms (ABF) software development tool was used to define the modules and screens which comprise the QIMS Pilot application. These specifications together with the QIMS information model and corresponding database definition constitute the QIMS technical specification and implementation description presented herein. The QIMS Pilot Project represents a completed software product which has been released for production use. Further extension projects are planned which will release new versions for QIMS. These versions will offer expanded and enhanced functionality to meet further customer requirements not accommodated by the QIMS Pilot Project.

Deconing controllers are developed for a spinning spacecraft, where the control mechanism is that of axial or radial moving masses that are used to produce intentional, transient principal axis misalignments. A single mass axial controller is used to motivate the concept, and then axial and radial dual mass controllers are described. The two mass problem is of particular interest since spacecraft imbalances can be simultaneously removed with the same control logic. Each controller is tested via simulation for its ability to eliminate existing coning motion for a range of spin rates. Both controllers are developed via a linear-quadratic-regulator synthesis procedure, which is motivated by their multi-input/multi-output nature. The dynamic coupling in the radial two mass control problem introduces some particularly interesting design complications.

A two-stage self-organizing neural network architecture has been applied to object recognition in Synthetic Aperture Radar imagery. The first stage performs feature extraction and implements a two-layer Neocognitron. The resulting feature vectors are presented to the second stage, an ART 2-A classifier network, which clusters the features into multiple target categories. Training is performed off-line in two steps. First, the Neocognitron self-organizes in response to repeated presentations of an object to recognize. During this training process, discovered features and the mechanisms for their extraction are captured in the excitatory weight patterns. In the second step, Neocognitron learning is inhibited and the ART 2-A classifier forms categories in response to the feature vectors generated by additional presentations of the object to recognize. Finally, all training is inhibited and the system tested against a variety of objects and background clutter. In this paper we report the results of our initial experiments. The architecture recognizes a simulated tank vehicle at arbitrary azimuthal orientations at a single depression angle while rejecting clutter and other object returns. The neural architecture has achieved excellent classification performance using 20 clusters.

The effects of orientation and stress on chemically prepared Pb(Zr,Ti)O3 (PZT) film properties have been determined. Systematic modification of the underlying substrate technology has made it possible to fabricate suites of films that have various degrees of orientation at a constant stress level, and to fabricate films that are in different states of stress but have similar orientation. Highly oriented films of the following compositions have been fabricated: PZT 60/40, PZT 40/60, and PZT 20/80. Remanent polarizations ( approximately=60 mu C/cm2) greater than those of the best bulk polycrystalline ferroelectrics were obtained for PZT 40/60 films that were under compression and highly.

This paper presents results of a set of numerical experiments performed bo benchmark the Cell-Centered Implicit Continuous-fluid Eulerian (CCICE), and to determine their limitations as flow solvers for water entry and water exit simulations.

Translations of two pioneering Russian papers on antenna theory are presented. The first paper provides a treatise on finite-length dipole antennas; the second paper addresses infinite-length, impedance-loaded transmitting antennas.

This paper will include a brief overview of the components of the QUICKSILVER suite and its current modeling capabilities. As time permits, results from sample applications will be shown, including time animations of simulation results.

An analytic model with no free parameters has been developed which accurately describes thermally-stimulated-current (TSC) measurements spanning more than a factor of 50 in average heating rate. The model incorporates Schottky electric-field-induced barrier lowering and a temperature-dependent “attempt-to-escape frequency” equal to ∼1014 Hz at 300°C. Applying this model to TSC measurements provides significantly improved estimates of the energy distribution of trapped holes in irradiated SiO2. All devices examined, including soft and (wet and dry) hard oxides from five process technologies, show similar energy distributions, with a minor peak at ∼1.2 eV and a broad major peak centered ∼1.7-2.0 eV above the SiO2 valence band. These energies are closer to photoinjection and tunneling estimates of trapped-hole energy in the literature than previous estimates based on TSC or thermal annealing. We also find that the trapped-electron density in irradiated SiO2 is proportional to the trapped-hole density over a wide range of irradiation conditions. Both the trapped-hole and trapped-electron densities scale with the applied oxide electric field (Eox) during irradiation as ∼(Eox)-1/2. These results strongly support the idea that electrons are trapped at sites associated with trapped holes. Wet gate oxides are found to trap significantly fewer electrons per trapped hole (∼16%) than dry oxides (∼48%), suggesting that, on average, holes may be trapped closer to the Si/SiO2 interface in the dry oxides than in the wet oxides. Possible models of the trapped-hole/trapped-electron complex are described, and implications for device long-term reliability and annealing response are discussed. © 1992 IEEE

The UNIX LANs in 1500 are experiencing explosive growth. The individual departments are creating LANs to address their particular needs; however, at the same time, shared software tools between the departments are becoming more common. It is anticipated that users will occasionally need access to various department software and/or LAN services, and that support personnel may carry responsibilities which require familiarization with multiple environments. It would be beneficial to users and support personnel if the various department environments share some basic similarities, allowing somewhat transparent access. This will become more important when departments share specific systems, as 1510 and 1550 have proposed with an unclassified UNIX system. Therefore, standards/conventions on the department LANs and the central site systems have to be established to allow for these features. it should be noted that the goal of the UEC is to set standards/conventions which affect the users and provide some basic structure for software installation and maintenance; it is not the intent that all 1500 LANs be made identical at an operating system and/or hardware level. The specific areas of concern include: (1) definition of a non-OS file structure; (2) definition of an interface for remote mounted file systems; (3) definition of a user interface for public files; (4) definition of a basic user level environment; and (5) definition of documentation requirements for public files (shared software). Each of these areas is addressed in this paper.

This document contains implementation details for the Sandia Management Restructure Study Team (MRST) Prototype Information System, which resides on a Sun SPARC II workstation employing the INGRES RDBMS. The INGRES/Windows 4GL application editor was used to define the components of the two user applications which comprise the system. These specifications together with the MRST information model and corresponding database definition constitute the MRST Prototype Information System technical specification and implementation description presented herein. The MRST Prototype Information System represents a completed software product which has been presented to the Management Restructure Study Team to support the management restructing processes at Sandia National Laboratories.

Finite element analyses of oil-filled caverns were performed to investigate the effects of cavern depth on surface subsidence and storage loss, a primary performance criteria of SPR caverns. The finite element model used for this study was axisymmetric, approximating an infinite array of caverns spaced at 750 ft. The stratigraphy and cavern size were held constant while the cavern depth was varied between 1500 ft and 3000 ft in 500 ft increments. Thirty year simulations, the design life of the typical SPR cavern, were performed with boundary conditions modeling the oil pressure head applied to the cavern lining. A depth dependent temperature gradient of 0.012{degrees}F/ft was also applied to the model. The calculations were performed using ABAQUS, a general purpose of finite element analysis code. The user-defined subroutine option in ABAQUS was used to enter an elastic secondary creep model which includes temperature dependence. The calculations demonstrated that surface subsidence and storage loss rates increase with increasing depth. At lower depths the difference between the lithostatic stress and the oil pressure is greater. Thus, the effective stresses are greater, resulting in higher creep rates. Furthermore, at greater depths the cavern temperatures are higher which also produce higher creep rates. Together, these factors result in faster closure of the cavern. At the end of the 30 year simulations, a 1500 ft-deep cavern exhibited 4 percent storage loss and 4 ft of subsidence while a 3000 ft-deep cavern exhibited 33 percent storage loss and 44 ft of subsidence. The calculations also demonstrated that surface subsidence is directly related to the amount of storage loss. Deeper caverns exhibit more subsidence because the caverns exhibit more storage loss. However, for a given amount of storage loss, nearly the same magnitude of surface subsidence was exhibited, independent of cavern depth.

This economic analysis compares human and robotic TRUPACT unloading at the Waste Isolation Pilot Plant. Robots speed up the unloading process, reduce human labor requirements, and reduce human exposure to radiation. The analysis shows that benefit/cost ratios are greater than one for most cases using government economic parameters. This suggests that robots are an attractive option for the TRUPACT application, from a government perspective. Rates of return on capital investment are below 15% for most cases using private economic parameters. Thus, robots are not an attractive option for this application, from a private enterprise perspective.

Technologies that use carbon and mixed metal oxides as the electrode material have been pursued for the purpose of producing high-reliability double-layer capacitors (DLCs). The author demonstrates their environmental stability in temperature, shock, vibration, and linear acceleration. She reviews the available test data for both types of DLCs under these stress conditions. This study suggests that mixed metal oxides and carbon-based double-layer capacitors can survive robust environments if packaged properly, and that temperature decreases performance of double-layer capacitors.

We describe a simple engineering model applicable to stand-off “Whipple bumper” shields, which are used to protect space-based assets from impacts by orbital debris particles. The model provides a framework for analyzing: 1) the parameter limits governing the penetration and breakup or decomposition of the hypervelocity debris particle; 2) the behavior of the induced debris cloud, including its velocity and divergence; and 3) the design and optimization of the stand-off shield for a specific threat and level of protection required. The model is normalized to actual stand-off debris shield experiments and multi-dimensional numerical simulations at impact velocities of ~10 km/s. The subsequent analysis of a current space station shield design suggests that: 1) for acceptable levels of protection, stand-off shields can be significantly thinner than previously thought; and 2) with the proper balance between shield thickness and stand-off distance, the total shield mass can be reduced substantially.

A series of experiments has been performed on the Sandia Hypervelocity Launcher to determine the performance limits of conventional Whipple shields against representative 0.8 g aluminum orbital debris plate-like fragments with velocities of 7 and 10 km/s. Supporting diagnostics include flash X-rays, high speed photography and transient digitizers for timing correlation. Two Whipple shield designs were tested with either a 0.030 cm or a 0.127 cm thick front sheet and a 0.407 cm thick backsheet separated by 30.5 cm. These two designs bracket the ballistic penetration limit curve for protection against these debris simulants for 7 km/s impacts.

This document describes the Temperature Monitoring System for the RHEPP project at Sandia National Laboratories. The system is designed to operate in the presence of severe repetitive high voltage and electromagnetic fields while providing real time thermal data on component behavior. The thermal data is used in the design and evaluation of the major RHEPP components such as the magnetically switched pulse compressor and the linear induction voltage adder. Particular attention is given to the integration of commercially available hardware and software components with a custom written control program. While this document is intended to be a reference guide, it may also serve as a template for similar applications. 3 refs.

The Choice Coordination Problem with k alternatives (k-CCP) was introduced by Rabin in 1982 [Rab82]. The goal is to design a wait-free protocol for n asynchronous processes which causes all correct processes to agree on one out of k possible alternatives. The agreement on a single choice is complicated by the fact that there is no a priori agreement on names for the alternatives. Furthermore processes must state their choice and do all communication via registers associated with the alternatives. We exactly characterize when the k-CCP can be solved deterministiclly, prove upper and lower space bounds for deterministic solutions, and provide a randomized protocol which is significantly better than the deterministic lower bound.

This bibliography contains 34 references concerning utilizing benchmarking in the management of businesses. Books and articles are both cited. Methods for gathering and utilizing information are emphasized. (GHH)

In this paper we take a new look at the tomographic formulation of spotlight mode synthetic aperture radar (SAR), so as to include the case of targets having three-dimensional structure. This bridges the work of David C. Munson and his colleagues, who first described SAR in terms of two-dimensional tomography, with Jack Walker`s original derivation of spotlight mode SAR imaging via Doppler analysis. The main result is to demonstrate that the demodulated radar return data from a spotlight mode collection represent a certain set of samples of the three-dimensional Fourier transform of the target reflectivity function, and to do so using tomographic principles instead of traditional Doppler arguments. We then show that the tomographic approach is useful in interpreting the two-dimensional SAR image of a three-dimensional scene. In particular, the well-known SAR imaging phenomenon commonly referred to as layover is easily explained in terms of tomographic projection. 4 refs.

Short communication.

The Sandia Airborne Computer (SANDAC) is a small, modular, high performance, multi-processor computer originally designed for aerospace applications. It can use a combination of Motorola 68020 and 68040 based processor modules along with AT&T DSP32C based signal processing modules. The system is designed to use up to 15 processors in almost any combination and a complete system can include up to 20 modules. Depending on the mix of processors, total computational throughput can range from 2.5 to greater than 225 million instructions per second (MIPS). The system is designed so that processors can access all resources in the machine and the inter-processor communication details are completely transparent to the software. In addition to processors, the system includes input/output, memory, and special function modules. Because of its ease of use, small size, durability, and configuration flexibility, SANDAC has been used on applications ranging from missile navigation, guidance and control systems to medical imaging systems. © 1992.

The unit cell shape of thick frequency selective surfaces, or dichroic plate, is dependent on its frequency requirements. One aperture shape may be chosen to give wider bandwidths, and another chosen for sharper frequency roll-off. This is analogous to circuits where the need for differing frequency response determines the circuit topology. Acting as spatial frequency filters, dichroics are a critical component in supporting the Deep Space Network (DSN) for spacecraft command a control up links as well as spacecraft down links. Currently these dichroic plates separate S-band at 2.0--232 GHz from X-band at 8.4--8.45 GHz. But new spacecraft communication requirements are also calling for an up link frequency at 7.165 GHz. In addition future spacecraft such as Craft/Casssini will require dichroics effectively separating K{sub a}-band frequencies in the 31--35 GHz range. The requirements for these surfaces are low transmission loss of < 0.1 dB at high power levels. Also is important to maintain a minimal relative phase shift between polarizations for circular polarization transmission. More current work has shown the successful demonstration of design techniques for straight, rectangular apertures at an incident angle of 30{degrees}. The plates are air-filled due to power dissipation and noise temperature considerations. Up-link frequency powers approach 100 kW making dielectrics undesirable. Here we address some of the cases in which the straight rectangular shape may have limited usefulness. For example, grating lobes become a consideration when the bandwidth required to include the new frequency of 7.165 GHz conflicts with the desired incident angle of 30{degrees}. For this case, the cross shape`s increased packing density and bandwidth could make it desirable. When a sharp frequency response is required to separate two closely space K{sub a}-band frequencies, the stepped rectangular aperture might be advantageous. 5 refs.

Phase II of the Long Valley Exploratory Well was completed to a depth of 7588 feet in November 1991. The drilling comprised two sub-phases: (1) drilling 17-1/2 inch hole from the Phase I casing shoe at 2558 feet to a depth of 7130 feet, plugging back to 6826 feet, and setting 13-3/8 inch casing at 6825 feet, all during August--September 1991; and (2) returning in November to drill a 3.85-inch core hole deviated out of the previous wellbore at 6868 feet and extending to 7588 feet. Ultimate depth of the well is planned to be 20,000 feet, or at a bottomhole temperature of 500{degrees}C, whichever comes first. Total cost of this drilling phase was approximately $2.3 million, and funding was shared about equally between the California Energy Commission and the Department of Energy. Phase II scientific work will commence in July 1992 and will be supported by DOE Office of Basic Energy Sciences, DOE Geothermal Division, and other funding sources.

Short communication.

Several closed form trajectory solutions have been developed for low-thrust interplanetary flight and used with patched conies for analysis of combined propulsion systems. The solutions provide insight into alternative types of Mars missions, and show considerable mass savings for fast crewed missions with outbound trip times on the order of 90-100 days.

Nuclear Thermal Propulsion (NTP) has been identified as a critical technology in support of the NASA Space Exploration Initiative (SEI). In order to safely develop a reliable, reusable, long-lived flight engine, facilities are required that will support ground tests to qualify the nuclear rocket engine design. Initial nuclear fuel element testing will need to be performed in a facility that supports a realistic thermal and neutronic environment in which the fuel elements will operate at a fraction of the power of a flight weight reactor/engine. Ground testing of nuclear rocket engines is not new. New restrictions mandated by the National Environmental Protection Act of 1970, however, now require major changes to be made in the manner in which reactor engines are now tested. These new restrictions now preclude the types of nuclear rocket engine tests that were performed in the past from being done today, A major attribute of a safely operating ground test facility is its ability to prevent fission products from being released in appreciable amounts to the environment. Details of the intricacies and complications involved with the design of a fuel element ground test facility are presented in this report with a strong emphasis on safety and economy.

Several new neutron cross section libraries, such as ENDF/ B-VI and IRDF-90, have recently been made available to the dosimetry community. Recommendations are made for the source selection of reaction cross sections that vary significantly among the libraries. In general, integral parameters from spectra obtained from unfold/adjustment codes using the new cross sections will not significantly change. A 61-reaction compendium of dosimetry cross sections drawn from existing evaluations has been compiled for use at the Sandia National Laboratories Radiation Metrology Laboratory. This dosimetry library (SNLRML) is recommended for use in spectrum determination with unfold/ adjustment methods. © 1992 IEEE

A rapid deployment access delay system (RAPADS) has been designed to provide high security protection of valued assets. The system or vault is transportable, modular, and utilizes a pin connection design. Individual panels are attached together to construct the vault. The pin connection allows for quick assembly and disassembly, and makes it possible to construct vaults of various sizes to meet a specific application. Because of the unique pin connection and overlapping joint arrangement, a sequence of assembly steps are required to assembly the vault. As a result, once the door is closed and locked, all pin connections are concealed and inaccessible. This provides a high level of protection in that no one panel or connection is vulnerable. This paper presents the RAPADS concept, design, fabrication, and construction.

One of the most challenging applications facing the computer community is development of effective adaptive human-computer interface. This challenge stems from the complex nature of the human part of this symbiosis. The application of this discipline to the environmental restoration and waste management is further complicated due to the nature of environmental data. The information that is required to manage environmental impacts of human activity is fundamentally complex. This paper will discuss the efforts at Sandia National Laboratories in developing the adaptive conceptual model manager within the constraint of the environmental decision-making. A computer workstation, that hosts the Conceptual Model Manager and the Sandia Environmental Decision Support System will also be discussed.

The Yucca Mountain Site Characterization Project is studying Yucca Mountain in southwestern Nevada as a potential site for a high-level nuclear waste repository. Site characterization includes surface-based and underground testing. Analyses have been performed to design site characterization activities with minimal impact on the ability of the site to isolate waste, and on tests performed as part of the characterization process. One activity of site characterization is the construction of an Exploratory Studies Facility, consisting of underground shafts, drifts, and ramps, and the accompanying surface pad facility and roads. The information in this report addresses the following topics: (1) a discussion of the potential effects of surface construction water on repository-performance, and on surface and underground experiments; (2) one-dimensional numerical calculations predicting the maximum allowable amount of water that may infiltrate the surface of the mountain without affecting repository performance; and (3) two-dimensional numerical calculations of the movement of that amount of surface water and how the water may affect repository performance and experiments. The results contained herein should be used with other site data and scientific/engineering judgement in determining controls on water usage at Yucca Mountain. This document contains information that has been used in preparing Appendix I of the Exploratory Studies Facility Design Requirements document for the Yucca Mountain Site Characterization Project.

The focus of this paper is on changes in perceptions of the risks associated with nuclear waste management over time. In particular, we are interested in the kinds of change that take place when the management programs, and those who are charged with implementing them, are subject to intensive public debate over an extended period of time. We are undertaken an over-time study of perceived risks in Colorado and New Mexico by implementing sequential random household surveys in each state, timed at six month intervals. This study employs three of these surveys, spanning the period from summer, 1990 to summer, 1991. Using these data, we examine the dynamics that may underlie variations in perceived risks over time. In particular, our analysis is focused on changes in the roles played by (1) basic political orientations (i.e. political ideology) and (2) trust in those who advocate conflicting policy positions.

Midway Valley, located at the eastern base of the Yucca Mountain in southwestern Nevada, is the preferred location of the surface facilities for the potential high-level nuclear waste repository at Yucca Mountain. One goal in siting these surface facilities is to avoid faults that could produce relative displacements in excess of 5 cm in the foundations of the waste-handling buildings. This study reviews existing geologic and geophysical data that can be used to assess the potential for surface fault rupture within Midway Valley. Dominant tectonic features in Midway Valley are north-trending, westward-dipping normal faults along the margins of the valley: the Bow Ridge fault to the west and the Paintbrush Canyon fault to the east. Published estimates of average Quaternary slip rates for these faults are very low but the age of most recent displacement and the amount of displacement per event are largely unknown. Surface mapping and interpretive cross sections, based on limited drillhole and geophysical data, suggest that additional normal faults, including the postulated Midway Valley fault, may exist beneath the Quaternary/Tertiary fill within the valley. Existing data, however, are inadequate to determine the location, recency, and geometry of this faulting. To confidently assess the potential for significant Quaternary faulting in Midway Valley, additional data are needed that define the stratigraphy and structure of the strata beneath the valley, characterize the Quaternary soils and surfaces, and establish the age of faulting. The use of new and improved geophysical techniques, combined with a drilling program, offers the greatest potential for resolving subsurface structure in the valley. Mapping of surficial geologic units and logging of soil pits and trenches within these units must be completed, using accepted state-of-the-art practices supported by multiple quantitative numerical and relative age-dating techniques.

Sandia National Laboratories (SNL) is a Department of Energy multiprogram engineering and scientific facility with unique design, development, and test capabilities arising from their work in nuclear weapons, energy resources, defense systems, nuclear safeguards, and specialized scientific endeavors. To support these programs, they have developed instrumentation and telemetry expertise not available elsewhere. This technology is applicable to projects in government and industry. Since the 1950s, they have applied our technical competence to meet difficult challenges with innovative solutions to data acquisition and telemetry problems. Sandia - with experience in fields as diverse as parachute design and plasma physics, geology and rocket guidance, human factors and high-speed aerodynamics, non-destructive testing and satellite communications - can use the power of synergism among our many disciplines to solve your complex problems of data and acquisition and analysis. SNL solves difficult data acquisition problems for extreme environments with expertise in advanced telemetry techniques, high data rate telemetry design, specialized electronics packaging, MIL-STD-1553 communications, instrumentation development, real-time data analysis, project management, specialized testers and data encryption.

Pretest analysis of a heated block test, proposed for the Exploratory Studies Facility at Yucca Mountain, Nevada, was conducted in this investigation. Specifically, the study focuses on the evaluation of the various designs to drill holes and cut slots for the block. The thermal/mechanical analysis was based on the finite element method and a compliant-joint rock-mass constitutive model. Based on the calculated results, relative merits of the various test designs are discussed.

Photovoltaic energy systems have historically been treated as a bulk power generation source for the future. However, utilities and other agencies involved with electrification throughout the world are beginning to find photovoltaics a least-cost option to meet specific loads both for themselves and their customers, in both off-grid and grid-connected applications. These expanding markets offer the potential of hundreds of megawatts of sales in the coming decade, but a strategy addressing both industrial growth and user acceptance is necessary to capitalize on this opportunity. 11 refs.

Phase mixing of transverse oscillations changes the nature of the ion hose instability from an absolute to a convective instability. The stronger the phase mixing, the faster an electron beam reaches equilibrium with the guiding ion channel. This is important for long distance propagation of relativistic electron beams where it is desired that transverse oscillations phase mix within a few betatron wavelengths of injection and subsequently an equilibrium is reached with no further beam emittance growth. In the linear regime phase mixing is well understood and results in asymptotic decay of transverse oscillations as 1/Z{sup 2} for a Gaussian beam and channel system, Z being the axial distance measured in betatron wavelengths. In the nonlinear regime (which is likely mode of propagation for long pulse beams) results of the spread mass model indicate that phase mixing is considerably weaker than in the regime. In this paper we consider this problem of phase mixing in the nonlinear regime. Results of the spread mass model will be shown along with a simple analysis of phase mixing for multiple oscillator models. Particle simulations also indicate that phase mixing is weaker in nonlinear regime than in the linear regime. These results will also be shown. 3 refs., 4 figs.

Photovoltaic (PV) systems are increasing in popularity in the northern latitudes and in the arctic regions in the state of Alaska. This increased interest and the high cost of providing electric power in these remote areas have prompted the Alaska Energy Authority (AEA) to request assistance from the Photovoltaic Design Assistance Center at Sandia National Laboratories. A project to investigate the feasibility of using PV-Diesel hybrid power systems in small villages in Alaska was started in 1989. Data acquisition systems (DAS) were designed and installed in selected villages to obtain resource and load information. The DAS is described and village electrical and resource data are presented. Simulations were run using the collected village data and actual cost data provided by the AEA. Results of the simulations and the economic analysis are presented. 5 refs., 8 figs.

Fabrication of high-efficiency silicon solar cells in an industrial environment requires a different optimization than in a laboratory environment. Strategies are presented for process development of high-efficiency silicon solar cells, with a goal of simplifying technology transfer into an industrial setting. The strategies emphasize the use of statistical experimental design for process optimization, and the use of baseline processes and cells for process monitoring and quality control. 8 refs.

The purpose of this paper is to develop an analytical model to convert ballistic limit curves obtained from flat projectile experiments to ballistic limit curves based on equivalent diameter spheres. Results from a test program involving flat plat projectiles conducted at Sandia National Laboratories are compared against the predicted performance of equivalent spherical projectiles as determined from the Wilkinson and Cour-Palais penetration equations. The developed method demonstrates good correlation of the ballistic limit of the shield concept for the flat plate projectiles to the theoretical ballistic limit for equivalent spheres as predicted by the penetration equations. 3 refs.

PRA studies are being extended to include a wider spectrum of reactor plants than was considered in NUREG-1150. There is a need for computationally simple models for Direct Containment Heating (DCH) that could be used for screening studies aimed at identifying potentially significant contributors to risk. This paper discusses two adiabatic equilibrium models that are candidates for the task. The first, a 1-cell model, places a true upper bound on DCH loads. This upper bound, however, often far exceeds reasonable expectations of containment loads based on best estimate CONTAIN calculations or experiment observations. In this paper, a 2-cell model is developed that largely captures the major mitigating features of containment compartmentalization, thus providing more reasonable estimates of the containment load. Predictions of the equilibrium models are compared with experiment data from the Limited Flight Path (LFP) test series conducted at Sandia National Laboratories.

The CONTAIN code is currently being used to predict containment thermal hydraulic conditions during design basis and severe accidents for advanced light water reactor (ALWR) designs such as the Westinghouse AP600. In the AP600 design, a passive containment cooling system (PCCS) is used for reducing long-term overpressure during accidents. CONTAIN models for heat and mass transfer within the AP600 containment and outer air cooling channel are verified by comparing recent CONTAIN calculations to integral test data obtained by Westinghouse in their PCCS Integral Test Facility. The comparison includes test in which the outer containment wall is both dry and wet, that is, the wet tests involve an evaporative water film that enhances heat transfer as will be the case for AP600. The appropriateness of the heat and mass transfer analogy methodology used in the CONTAIN code is demonstrated. Code model limitations are discussed along with model development plans and applications for AP600.

An additive three step process has been developed for patterned deposition of Cu onto poly(tetrafluoroethylene) (PTFE). The first step involves patterned irradiation with X-rays or electrons which is thought to cross link the PTFE surface; step two involves chemical etching with the result that only the non-irradiated areas are etched; and step three involves selective chemical vapor deposition (CVD) of Cu onto the etched surface at 200 C using (hexafluoroacetylacetonato)Cu(I) trimethylphosphine ((hfac)Cu(PMe{sub 3})). The non-irradiated areas of the surface are covered by a continuous, dense Cu film with X-ray photoelectron spectra show to contain only surface impurities that are easily removed by a short Ar ion sputter. The irradiated areas show the presence of only C and F, characteristic of PTFE.

The first experiment of the Integral Effects Test (IET-1) series was conducted to investigate the effects of high pressure melt ejection (HPME) on direct containment heating (DCH). A 1:10 linear scale model of the Zion reactor pressure vessel (RPV), cavity, instrument tunnel, and subcompartment structures were constructed in the Surtsey Test Facility at Sandia National Laboratories (SNL). The RPV was modelled with a melt generator that consisted of a steel pressure barrier, a cast MgO crucible, and a thin steel inner liner. The melt generator/crucible had a semi-hemispherical bottom head containing a graphite limitor plate with a 3.5 cm exit hole to simulate the ablated hole in the RPV bottom head that would be formed by tube ejection in a severe nuclear power plant (NPP) accident. The reactor cavity model contained 3.48 kg of water with a depth of 0.9 cm that corresponded to condensate levels in the Zion plant. A steam driven iron oxide/aluminum/chromium thermite was used to simulate HPME. A relatively small steam explosion occurred in the cavity during IET-1. Steam blowthrough entrained debris into the Surtsey vessel resulting in a peak pressure increase in Surtsey of 98 kPa. The Surtsey vessel had been previously inerted with N{sub 2}. The total debris mass ejected into the Surtsey vessel was 43 kg. The hydrogen concentration was 3.1 mol.% in the vessel at equilibrium. The concentration measured inside the subcompartment structures immediately following HPME transient was 20.7 mol.% H{sub 2}. 4 refs., 17 figs., 5 tabs.

During the RADLAC II open-air beam propagation experiments this last year three separate optical diagnostics were used. (1) Streak cameras were deployed to measure matched beam radius and centroid versus time. (2) Three gated, intensified TV cameras were used to image the beam from the end of the propagation range. They gave beam radius and centroid for three slices of the beam over a five meter propagation length. (3) Open shutter cameras were developed to give the time-averaged beam position over the entire propagation range. Data from all three diagnostics were digitized, stored in files on a computer, and post-processed to give temporally and spatially resolved beam size and position. These diagnostics used beam induced air-fluorescence as the mechanism to provide a prompt signal representative of the beam current density. Previous experiments and analysis have shown that the radiation is prompt with the intensity proportional to the beam current density for high energy, high current electron beams propagating in full density air.

Detailed geometric models have been used within a graphical simulation environment to study transportation cask facility design and to perform design and analyses of robotic systems for handling of nuclear waste. The models form the basis for a robot control environment which provides safety, flexibility, and reliability for operations which span the spectrum from autonomous control to tasks requiring direct human intervention.

We have designed and manufactured a test chip devoted to the study of interconnect voiding. The test chip is suitable for evaluating theoretical models, acceleration recipes, and the effects of process variations. We describe the chip and a simple, stress-free packaging technique that eliminates any stress to the chip from die bonding or packaging thermal cycles. With this test chip, we can perform many necessary and desirable experiments: determining stress, observing or stimulating void growth, profiling hydrogen concentrations, and measuring excess current noise. We report here preliminary measurements of residual stress, observations of voids, and determinations of hydrogen concentrations of hydrogen concentration under variations in aluminum annealing and passivation. In agreement with observations elsewhere, we find that passivations which differ greatly in intrinsic stress do not differ much in the stress they impart to patterned metal; some workers have suggested instead that excess hydrogen in the aluminum contributes to voiding. Following this lead, we have used nuclear reaction analysis to profile the hydrogen concentration in passivation, metallization, barrier metal, and interlevel dielectric and present some preliminary measurements here. We conclude that passivated metallization may contain as much as 0.1 atomic % hydrogen. 10 refs.

This paper provides a summary and status report for two ongoing experimental programs. The purpose of each program is to determine the behavior of certain components of the containment pressure boundary when subjected to severe accident conditions. The first program is investigating the effect of various parameters on tearing of the steel liner in reinforced concrete containments. The second will attempt to determine if worst-case containment loading conditions are capable of causing leakage through piping penetration bellows. The liner test program is almost complete; however, the bellows tests have not yet begun. Therefore, the emphasis of the paper is on the liner experiments. The research activities described herein are a part of the Containment Integrity Programs, which are managed by Sandia National Laboratories for the US Nuclear Regulatory Commission.

A Science Advisor Program has been established at Sandia National Laboratories (SNL) for the long term augmentation of math and science instruction in New Mexico schools. Volunteer SNL engineers and scientists team with the faculty of participating schools to enhance the teachers` abilities to capture and hold the student`s scientific imagination and develop their scientific skills. This is done primarily through providing laboratory resources, training the teachers how to use those resources, and advising how to obtain them in the future. In its first year, over 140 advisors teamed with 132 schools, for average weekly contact with 500 teachers and 10,000 students. Surveys indicate a general rise in frequency and quality of hands-on science instruction, as well as teacher and student attitudes. An expanded evaluation is planned for subsequent years.

The syntheses and physical properties of {kappa}-(ET){sub 2}Cu[N(CN){sub 2}]X (X=Br and Cl) are summarized. The {kappa}-(ET){sub 2}Cu[N(CN){sub 2}]Br salt is the highest {Tc} radical-cation based ambient pressure organic superconductor ({Tc}=11.6 K), and the {kappa}-(ET){sub 2}Cu[N(CN){sub 2}]Cl salt becomes a superconductor at even higher {Tc} under 0.3 kbar hydrostatic pressure ({Tc}=12.8 K). The similarities and differences between {kappa}-(ET){sub 2}Cu[N(CN){sub 2}]Br and {kappa}-(ET){sub 2}Cu(NCS){sub 2} ({Tc}=10.4 K) are presented. The X-ray structures at 127 K reveal that the the S{hor_ellipsis}S contacts shorten between ET dimers in the former compound while the S{hor_ellipsis}S contacts shorten within dimers in the latter. The difference in their ESR linewidth behavior is also explained in terms of the structural differences. A semiconducting compound, (ET)Cu[N(CN){sub 2}]{sub 2}, isolated during {kappa}-(ET){sub 2}Cu[N(CN){sub 2}]Cl synthesis is also reported. The ESR measurements of the {kappa}-(ET){sub 2}Cu[N(CN){sub 2}]Cl salt indicate that the phase transition near 40 K is similar to the spin density wave transition in (TMTSF){sub 2}SbF{sub 6}. A new class of organic superconductors, {kappa}-(ET){sub 2}Cu{sub 2}(CN){sub 3} and {kappa}-(ET){sub 2}Cu{sub 2}(CN){sub 3}-{delta}Br{delta}, is reported with {Tc}`s of 2.8 K (1.5 kbar) and 2.6 K (1 kbar), respectively.

We describe a new electrochemical processing technique based on porous silicon formation that can produce surface and buried insulators, conductors, and sacrificial layers required for silicon micromachining to fabricate micromechanical devices and sensors. Porosity and thickness of porous silicon layers for micromachining can be controlled to a relative precision better than 0.3% for porosities ranging from 20--80% and thicknesses ranging from sub- micron to hundreds of microns. The technique of using porous silicon has important implications for microfabrication of silicon electromechanical devices and sensors. The high relative precision in realizing a given thickness is superior to that obtained with conventional chemical etches. 8 refs.

This paper discusses the development of the software for Source Term Analyses for Containment Evaluations (STACE). This software is being developed for the Source Term Technical Issue Resolution Program at Sandia National Laboratories (SNL) in support of the Cask Systems Development Program (CSDP) that is sponsored by the US Department of Energy`s Office of Civilian Radioactive Waste Management (OCRWM). STACE is a system of computer codes operating under a graphics-based controller that performs source term analysis of spent fuel transport casks. Output from STACE includes the cladding breach probability, the releasable radionuclide concentrations, and maximum permissible gas flow rates past the closure seals. STACE is anticipated being used for on- and off-site situations related to the handling and transport of spent fuel casks.

This paper presents a methodology for determining the response of spent fuel assembly spacer grids subjected to transport cask impact loading. The spacer grids and their interaction with rod-to-rod loading are the most critical components governing the structural response of spent fuel assemblies. The purpose of calculating the assembly response is to determine the resistance to failure of spent fuel during regulatory transport. The failure frequency computed from these analyses is used in calculating category B spent fuel cask containment source term leakage rates for licensing calculations. Without defensible fuel rod failure frequency prediction calculations, assumptions of 100% fuel failure must be made, leading to leak tight cask design requirements.

A methodology for determining the probability spent-fuel cladding breach due to normal and accident class B cask transport conditions is introduced. This technique uses deterministic stress analysis results as well as probabilistic cladding material properties, initial flaws, and breach criteria. Best estimates are presented for the probability distributions of irradiated Zircaloy properties such as ductility and fracture toughness, and for fuel rod initial conditions such as manufacturing flaws and PCI part-wall cracks. Example analyses are used to illustrate the implementation of this methodology for a BWR (GE 7 {times} 7) and a PWR (B&W 15 {times} 15) assembly. The cladding breach probabilities for each assembly are tabulated for regulatory normal and accident transport conditions including fire.

Residual stress states that are a direct result of fabrication and processing are known to exist inside wound capacitors. Considerable insights into the nature of these mechanical and thermomechanical stress states have been gained through the application of analytical prediction capabilities that have been developed for that purpose. For example, analysis shows where roll slip may occur in the capacitor due to steep wound tension gradients or low radial pressures, and how the tension loss of individual plies is distributed throughout the capacitor. Significant tension loss differences between dielectric and conducting plies has also been predicted, with conducting plies not only losing their initial winding tension, but actually experiencing a net compressive value of wound tension. While the results of these predictions are both quantitative and qualitative, only qualitative verification has been obtained thus far, such as visual observation of wrinkled conducting plies discovered in unwrapped capacitors. The purpose of this paper is to describe two experimental activities that were undertaken to support the analytical modeling effort and provide quantitative, experimental verification of some of the analysis predictions.

The technical issues brought about by recent federal mandates are reviewed and discussed. Progress made in the elimination of CFCs is briefly reviewed. The problems, implications, and status of pending anti-lead legislation and taxation are discussed at length. Recommendations are made for the enactment of rational, fair, and orderly legislation and taxation.

This paper describes current research and development on a miniaturized sensing system for use during in situ characterization of nuclear waste storage tanks. Sandia is designing this sensing system as a tool for a large robotic arm that is deployed through an access port in the top of a storage tank. While the robot arm scans the sensing package over the waste, a distributed computing system acquires sensor data, correlates the data with the position of the robot, and produces maps of the chemical and radiological contents of the tanks in real time. We have built and demonstrated a first prototype system containing eight sensors. 53 refs.

Two revisions of the CONTAIN code, CONTAIN 1.11 and 1.12 , have recently been released. The purpose of this paper is to highlight the new features of these revisions and to discuss other new code features currently under development. The features of CONTAIN 1.11 discussed here include a quasi-mechanistic concrete outgassing model, the connected structure option for heat conduction between compartments, and a new approach for modeling forced convective heat transfer. The direct containment heating (DCH) models released as part of CONTAIN 1.12 are also discussed. New code features currently under development include a revised gas combustion model and a new multifield DCH model. New features of the revised combustion model include the treatment of spontaneous recombination and diffusion flames. CONTAIN plant calculations comparing the old and the revised combustion models are presented. The new features of the multifield DCH model are discussed, and demonstration calculations using this model to analyze a small scale experiment are presented.

A previous investigation of laser-induced damage mechanisms and corresponding thresholds in step-index, multimode fibers was motivated by an interest in optical systems for firing explosives. In the initial study, the output from a compact, multimode Nd/YAG laser was coupled into fiber cores of pure fused silica. End-face polishing steps were varied between successive fiber lots to produce improved finishes, and each fiber was subjected to a sequence of progressively increasing energy densities up to a value more than 80 J/cm{sup 2}. Essentially all of the tested fibers experienced a ``laser conditioning`` process at the front fiber face, in which a visible plasma was generated for one or more laser shots. Rather than produce progressive damage at the front surface, however, this process would eventually cease and leave the surface with improved damage resistance. Once past this conditioning process, the majority of fibers damaged at the rear end face. Other modes of damage were observed either at locations of fixturing stresses or at a location of high static tensile stress resulting from bends introduced to the fiber. The current experiments were conducted with a new laser having a shorter pulsewidth and a significantly different mode structure. The beam was injected into the fiber using a geometry that had been successful in the previous study in minimizing a damage mechanism which can occur at the core/cladding interface within the first few hundred fiber diameters. However, the different mode structure of the new laser apparently resulted in this mechanism dominating the current results.

The Department of Energy`s (DOE`s) Office of Civilian Radioactive Waste Management (OCRWM) is in the process of developing a new generation of casks to transport spent fuel from commercial nuclear reactor facilities to federal waste facilities. In evaluating the needs of the cask development program a number of unresolved technical issues with potential impacts on the transportation system were identified. This paper provides three samples of issues being addressed by the Cask Systems Development Program for technical resolution: (1) burn-up credit, (2) containment source term evaluation, and (3) weeping.

SMILE is a coaxial Self Magnetically Insulated Transmission Line voltage adder. It replaces the original beam line of the RADLAC II accelerator by a 12.5 m long cathode electrode. The anode electrode remains practically the same, consisting of the original eight insulating stacks or feeds which are connected with equal diameter stainless steel cylinders. The beam is produced at the end of the accelerator and is free of all the possible instabilities associated with accelerating gaps and magnetic vacuum transport. Annular beams with {beta}{perpendicular} {le} 0.1 and radius r{sub b} {le} 1 cm were routinely obtained and extracted from a small magnetically-immersed foilless electron diode. Results of the experimental evaluation are presented and compared with design parameters and numerical simulation predictions. 4 refs.

Abstract not provided.

In this paper, measurements on the quasi-isentropic compression of tungsten to stress levels of 250 GPa are reported. Results of these experiments have been compared to those obtained under shock loading conditions to comparable stresses. These experiments have allowed the determination of temperature, pressure, and loading rate effects on the dynamic yield strength of tungsten up to 250 GPa. These results show that the dynamic yield strength of tungsten is dependent on the loading rate with the strength being higher for the relatively slower rates of loading along the quasi-isentropic. The pressure dependence of the yield strength of tungsten is determined nearly independent of temperature effects from quasi-isentropic loading experiments to 250 GPa, because the temperature rise in an quasi-loading experiment is much lower than those associated with shock loading experiments.

Continuum dynamics codes are categorized as Lagrangian or Eulerian according to the motion of the mesh. A Lagrangian code`s mesh moves with the material, so no mass flows between cells. An Eulerian code`s mesh is stationary, so mass flows between the cells. Eulerian codes have improved to the point where they are routinely used to solve a broad variety of large deformation solid and fluid dynamics problems ranging from air flow over an airplane wing to meteor impact on space structures. This presentation will concentrate on multi-fluid Eulerian codes capable of modeling transient were propagation in solids. These codes use a two-step process to integrate the physics across a time step. The first step, referred to as the Lagrangian step, integrates the physics on a Lagrangian mesh across the time step. The field values are then at the new time, but they are on the distorted Lagrangian mesh. The second step, referred to as the remap step, remaps the data on the distorted Lagrangian mesh back to the original Eulerian mesh thus completing one time step. The algorithms used in the first step are similar to those used in modern Lagrangian codes but they must be extended to handle multi-material cells. The algorithms used in the second step are complex and must be very carefully chosen to minimize errors. These algorithms include second-order, monotone advection equations to calculate the quantities flowing between cells. They also require algorithms that construct material interfaces inside multi-material cells. The strength and limitations of currently used numerical techniques will be discussed. New code development activities that combine the best features on both Lagrangian and Elueian codes will also be discussed. These new codes will employ the strengths of both technologies to address problems that cannot be adequately solved at this time.

The Hybrid Thin-Slot Algorithm (HTSA) integrates a transient integral-equation solution for an aperture in an infinite plane into a finite-difference time-domain (FDTD) code. The technique was introduced for linear apertures and was extended to include wall loss and lossy internal gaskets. A general implementation for arbitrary thin slots is briefly described here. The 3-D FDTD-code TSAR was selected for the implementation. The HTSA does not provide universal solutions to the narrow slot problem, but has merits appropriate for particular applications. The HTSA is restricted to planar slots, but can solve the important case that both the width and depth of the slot are narrow compared to the FDTD spatial cell. IN addition, the HTSA is not bound to the FDTD discrete spatial and time increments, and therefore, high-resolution solutions for the slot physics are possible. The implementation of the HTSA into TSAR is based upon a ``slot data file`` that includes the cell indices where the desired slots are exist within the FDTD mesh. For an HTSA-defined slot, the wall region local to the slot is shorted, and therefore, to change the slot`s topology simply requires altering the file to include the desired cells. 7 refs.

The one-electron energy levels of icosahedral boron clusters have been calculated as a function of intericosahedral spacing maintaining the intraicosahedral spacing of {alpha}-boron. For crystalline lattice constants greater than 1.25 times the equilibrium one, band overlap occurs with concomitant metallic behavior. At smaller lattice constants, orbitals(bands) associated with bonds to adjacent icosahedra are lowered and orbitals(bands) associated with ``antibonds`` are raised. Four bands which were three quarters full become empty, while three bands which were empty become filled. This leads to an energy gap between the filled states and the empty states which accounts for the experimentally observed insulating behavior of this elemental material with three valence electrons per atom.

Verifying the velocity accuracy of a GPS receiver or an integrated GPS/INS system in a dynamic environment is a difficult proposition when many of the commonly used reference systems have velocity uncertainities of the same order of magnitude or greater than the GPS system. The results of flight tests aboard an aircraft in which multiple reference systems simultaneously collected data to evaluate the accuracy of an integrated GPS/INS system are reported. Emphasis is placed on obtaining high accuracy estimates of the velocity error of the integrated system in order to verify that velocity accuracy is maintained during both linear and circular trajectories. Three different reference systems operating in parallel during flight tests are used to independently determine the position and velocity of an aircraft in flight. They are a transponder/interrogator ranging system, a laser tracker, and GPS carrier phase processing. Results obtained from these reference systems are compared against each other and against an integrated real time differential based GPS/INS system to arrive at a set of conclusions about the accuracy of the integrated system.

Computer-aided molecular design methods were used to tailor binding sites for small substrate molecules, including CO{sub 2} and methane. The goal is to design a cavity, adjacent to a catalytic metal center, into which the substrate will selectively bind through only non-bonding interactions with the groups lining the binding pocket. Porphyrins are used as a basic molecular structure, with various substituents added to construct the binding pocket. The conformations of these highly-substituted porphyrins are predicted using molecular mechanics calculations with a force field that gives accurate predictions for metalloporhyrins. Dynamics and energy-minimization calculations of substrate molecules bound to the cavity indicate high substrate binding affinity. The size, shape and charge-distribution of groups surrounding the cavity provide molecular selectivity. Specifically, calculated binding energies of methane, benzene, dichloromethane, CO{sub 2} and chloroform vary by about 10 kcal/mol for metal octaethyl-tetraphenylporphyrins (OETPPs) with chloroform, dichloromethane, and CO{sub 2} having the lowest. Significantly, a solvent molecule is found in the cavity in the X-ray structures of Co- and CuOETPP crystals obtained from dichloromethane. 5 refs., 3 figs., 3 tabs.

Single Event Upset Imaging utilizes the scanning of a micro-focused MeV ion beams across an integrated circuit to test the upset response of the circuit to energetic heavy ions. Using this technique, the position dependence of logic state upsets, as well as the charge collection efficiency of an integrated circuit, can be directly measured with micron resolution. We present in this paper a review of a series of measurements carried out on the TA670 16K static random access memory chip which display this technique`s capabilities.

Short communication.

Hot cracking, or solidification cracking, is one of the most extensively studied phenomenon in welding metallurgy. The efforts made to identify the causes of this type of cracking have been driven by the negative commercial and engineering consequences resulting from the formation of these defects. Through judicious weld joint design, the mechanical restraint can be minimized, but it can never be entirely eliminated simply because metals expand and contract when heated and cooled, respectively. The localized nature of heat input in fusion welding insures a non-homogeneous thermal field being applied to the parts being welded, resulting in the development of strains in the as-solidifying weld metal. With the inherent limitations on the mechanical restraint factor, much research has gone into identifying those alloy compositions which minimize the microstructural factor required for hot cracking to occur. Examples from the author`s own research are presented as a tutorial to show how differential thermal analysis techniques have been used to study the chemical/microstructural factors associated with solidification and fusion zone hot cracking in nickel based engineering alloys. References to other uses of these techniques in related welding metallurgy studies are also given.

Dislocation formation in InAs{sub 1-x}Sb{sub x} buffer layers grown by metal-organic chemical vapor deposition is shown to be reproducibly enhanced by p-type doping at levels greater than or equal to the intrinsic carrier concentration at the growth temperature. To achieve a carrier concentration greater than 2 {times} 10{sup 18} cm{sup {minus}3}, the intrinsic carrier concentration of InSb at 475 C, p-type doping with diethylzinc was used. Carrier concentrations up to 6 {times} 10{sup 18} cm{sup {minus}3} were obtained. The zinc doped buffer layers have proven to be reproducibly crack free for InAs{sub 1-x}Sb{sub x} step graded buffer layers with a final composition of x = 0.12 and a strained layer superlattice with an average composition of x = 0.09. These buffer layers have been used to prepare SLS infrared photodiodes. The details of the buffer layer growth, an explanation for the observed Fermi level effect and the growth and characterization of an infrared photodiode are discussed.

The use of coatings on carbon-carbon materials to reduce the oxidation of carbon is of interest for the production of non-ablative aerospace structures. The arc-jet ground test facility can produce the high energy oxidizing environment necessary to simulate hypersonic flight in which to test candidate coatings. The test conditions usually required are characterized by material temperature and length of time the material remains at that temperature. Material specimens were exposed to high energy supersonic air exhausting from the NASA-Ames Research Center`s 20-MW arc-jet facility. The carbon-carbon materials were heated to required temperatures with arc-heated air for specified lengths of time. This report describes the test methodology and observations of those tests.

We described a new family of versatile, cascadable, optical switches with different functional characteristics -- latching, non-latching, and bistable -- using a single epitaxial structure base don the monolithic integration of photothyristors and surface-emitting layers. High performance optical switching characteristics have been achieved for all three switch archetypes. We also demonstrate the AND, OR, NAND, NOR, and INVERT optical logic functions using monolithic switch structures. 7 refs.

A boundary integral equation method for steady unsaturated flow in nonhomogeneous porous media is presented. Steady unsaturated flow in porous media is described by the steady form of the so-called Richards equation, a highly nonlinear Fokker-Planck equation. By applying a Kirchhoff transformation and employing an exponential model for the relation between capillary pressure and hydraulic conductivity, the flow equation is rendered linear in each subdomain of a piece-wise homogeneous material. Unfortunately, the transformation results in nonlinear conditions along material interfaces, giving rise to a jump in the potential along these boundaries. An algorithm developed to solve the nonhomogeneous flow problem is described and verified by comparison to analytical and numerical solutions. The code is applied to examine the moisture distribution in a layered porous medium due to infiltration from a strip source, a model for infiltration from shallow ponds and washes in arid regions.

Structural system identification is undergoing a period of renewed interest. Probabilistic approaches to physical parameter identification in analysis finite element models make uncertainty in test results an important issue. In this paper, we investigate this issue with a simple, though in many ways representative, structural system. The results of two modal parameter identification techniques are compared and uncertainty estimates, both through bias and random errors, are quantified. The importance of the interaction between test and analysis is also highlighted. 25 refs.

Pre-exposure induced stress corrosion cracking (SCC) of an Al-Li-Cu, AA 2090, was studied using a variety of test techniques. Results from SCC testing in a simulated isolated pit solution are correlated with electrochemical corrosion rate data obtained for individual phases in the subgrain boundary region. These experimental data, combined with existing data on the crevice chemistry of isolated pits in Al-Li alloys and X-ray diffraction studies of solid corrosion products formed in crevice environments are used to propose a model for pre-exposure induced cracking based on anodic dissolution along subgrain boundaries. Key features of the model are selective dissolution of the subgrain boundary T{sub 1} phase (Al{sub 2}CuLi) at the crack tip and passivation of crack walls by the formation of an Li{sub 2}[Al{sub 2}(OH){sub 6}]{sub 2}{center_dot}CO{sub 3}{center_dot}nH{sub 2}O barrier film.

The transportation risk evaluation code RADTRAN 4 is designed to evaluate doses and risks associated with the transportation of radioactive materials (Ne92). RADTRAN 4 may be used to calculate dose consequences for incident-free transportation and dose risks for accidents. Consequences of normal (or incident-free) transportation include doses to crew members, persons at stops, and members of the public sharing a route segment (on-link) and residing near the segment (off-link) during normal transportation. These dose estimates are not multiplied by a probability factor and, hence, are referred to as dose consequences. Calculated doses that might be incurred during accidents are multiplied by the probabilities of those accidents, and hence are referred to as dose risks. RADTRAN 4 includes a LINK option that allows the user to characterize each link or segment of a transportation route in greater detail than that provided by average or default values for route-related parameters.

This paper explains how an induction coilgun works and presents the factors which go into its design. Our purpose is to obtain algebraic expressions which, although crude, provide useful predictors of behavior, illustrate the dependence on various parameters, and suggest ways to optimize the design. Detailed prediction of the gun`s behavior can be obtained from simulation codes, such as SLINGSHOT.

Very high driving pressures (tens or hundreds of GPa), are required to accelerate flier plats to hypervelocities. This loading pressure pulse on the fiber plates must be nearly shockless to prevent the plate from melting or vaporizing. This is accomplished by using graded-density impactors referred to as ``pillows.`` When this graded-density material is used to impact a flier-plate in a modified two-stage light gas gun, nearly shockless megabar pressures are introduced into the flier plate. The pressure pulses must also be tailored to prevent spallation of the flier-plate. This technique has been used to launch nominally 1-mm-thick aluminum, magnesium and titanium (gram-size) intact plates to 10.4 km/s, and 0.5-mm-thick aluminum and titanium (half-gram size) intact plates to 12.2 km/s. This is the highest mass-velocity capability attained with laboratory launchers to data, and should open up new regimes of impact physics and lethality studies related to space sciences for laboratory investigations. 14 refs.

Fourier transform-infrared spectroscopy (FT-IR) was used to investigate the adsorption and thermally-induced decomposition of copper (I) {beta}-diketonate precursors of the type (hfac)CuL, where hfac is the hexafluoroacetylacetonate bidentate ligand and L is trimethylphosphine or 1,5-cyclooctadiene. The (hfac)CuPMe{sub 3} precursor desorbs from the surface at very low temperatures whereas the (hfac)Cu(1,5-COD) dissociates on adsorption, liberating 1,5-COD and leaving a surface(hfac)Cu complex which can subsequently disproportionate. Evidence is provided for hydrogen-bonding between the hfac ligand and the surface silanols for (hfac)CuPMe{sub 3}, but not for (hfac)Cu(1,5-COD). These results are consistent with the selective behavior of these precursors for copper deposition and suggest that the selectivity of the (hfac)CuPMe{sub 3} and (hfac)Cu(1, 5-COD) precursors may be due to the ability of the hfac ligand to hydrogen bond to the surface silanol groups.

The concept of allowing reactivity credit for the transmuted state of spent fuel offers both economic and risk incentives. This paper presents a general overview of the technical work being performed in support of the US Department of Energy (DOE) program to resolve issues related to the implementation of burnup credit. An analysis methodology is presented along with information representing the validation of the method against available experimental data. The experimental data that are applicable to burnup credit include chemical assay data for the validation of the isotopic prediction models, fresh fuel critical experiments for the validation of criticality calculations for various casks geometries, and reactor restart critical data to validate criticality calculations with spent fuel. The methodology has been specifically developed to be simple and generally applicable, therefore giving rise to uncertainties or sensitivities which are identified and quantified in terms of a percent bias in k{sub eff}. Implementation issues affecting licensing requirements and operational procedures are discussed briefly.

The US Department of Energy is sponsoring a research effort through Sandia National Laboratories and the University of Missour-Rolla to test a correlation for the upper shelf energy (USE) values obtained from the impact testing of subsize Charpy V-notch specimens to those obtained from the testing of full size samples. The program involves the impact testing of unirradiated and irradiated full, half, and third size Charpy V-notch specimens. To verify the applicability of the correlation on LWR materials unirradiated and irradiated full, half, and third size Charpy V-notch specimens of a commercial pressure vessel steel (ASTM A533 Grade B) will be tested. This paper will provide details of the program and present results obtained from the application of the developed correlation methodology to the impact testing of the unirradiated full, half, and third size A533 Grade B Charpy V-notch specimens.

Relativistic high current electron beams can be transported long distances across the geomagnetic field using the IFR (Ion focused Regime) technique. IFR is a method of providing strong electrostatic focusing and guiding of the beam. The guiding is sufficiently strong to allow the beam to transport any angle with respect to geomagnetic field. In the IFR method, first an ionizing laser (or any ionizing method) is used to create a preionized cylindrical channel.

We present a learning algorithm designed to improve robot path planning. The algorithm relies on an existing path planner to provide solutions to difficult tasks. From these solutions, it learns a sparse network of useful robot subgoals which guide and support fast planning. We analyze the algorithm theoretically by developing some general techniques useful in characterizing behaviors of probabilistic learning. We also demonstrate the effectiveness of the algorithm empirically with an existing path planner in practical environments. The learning algorithm not only reduces the time cost of existing planners, but also increases their capability in solving difficult tasks. 7 refs.

An understanding of the state of stress on faults is important for pre- and postclosure performance considerations for the potential high-level radioactive waste repository at Yucca Mountain. This paper presents the results of three-dimensional numerical analyses that provide estimates of the state of stress through time (10,000 years) along three major faults in the vicinity of the potential repository due to thermal stresses resulting from waste emplacement. It was found, that the safety factor for slip close to the potential repository increases with time after waste emplacement. Possible fault slip is predicted above and below the potential repository for certain loading conditions and times. In general, thermal loading reduces the potential for slip in the vicinity of the potential repository.

This paper presents a summary of the conduct and findings of the Exploratory Studies Facility Alternatives Study (ESF-AS). The Exploratory Studies Facility (ESF) is being planned for use in the characterization of a site for a potential high-level nuclear waste repository at Yucca Mountain, NV. The purpose of the ESF-AS were to identify and rank order ESF-repository options and to improve understanding of the favorable or unfavorable features of the ESF design. The analysis resulted in the ranking of 34 options, in accordance with the extent to which each option could achieve the objectives. Additional findings regarding design features that were identified as key elements in an option`s ability to provide good overall performance are also discussed.

Excavation stability in an underground nuclear waste repository is required during construction, emplacement, retrieval (if required), and closure phases to ensure worker health and safety, and to prevent development of potential pathways for radionuclide migration in the post-closure period. Stable excavations are developed by appropriate excavation procedures, design of the room shape, design and installation of rock support reinforcement systems, and implementation of appropriate monitoring and maintenance programs. In addition to the loads imposed by the in situ stress field, the repository drifts will be impacted by thermal loads developed after waste emplacement and, periodically, by seismic loads from naturally occurring earthquakes and underground nuclear events. A priori evaluation of stability is required for design of the ground support system, to confirm that the thermal loads are reasonable, and to support the license application process. In this report, a design methodology for assessing drift stability is presented. This is based on site conditions, together with empirical and analytical methods. Analytical numerical methods are emphasized at this time because empirical data are unavailable for excavations in welded tuff either at elevated temperatures or under seismic loads. The analytical methodology incorporates analysis of rock masses that are systematically jointed, randomly jointed, and sparsely jointed. In situ thermal and seismic loads are considered. Methods of evaluating the analytical results and estimating ground support requirements for all the full range of expected ground conditions are outlines. The results of a preliminary application of the methodology using the limited available data are presented. 26 figs., 55 tabs.

The Yucca Mountain Site Characterization Project is studying Yucca Mountain in southwestern Nevada as a potential site for a high-level nuclear waste repository. Site characterization includes surface-based and underground testing. Analyses have been performed to design site characterization activities with minimal impact on the ability of the site to isolate waste, and on tests performed as part of the characterization process. One activity of site characterization is the construction of an Exploratory Studies Facility, for which many design options are being considered, including shafts, drifts, and ramps. The information in this report pertains to: (1) engineering calculations of the potential distribution of residual water from constructing the shafts and drifts; (2) numerical calculations predicting the movement of residual construction water from the shaft and drift walls into the rock; and (3) numerical calculations of the movement of residual water and how the movement is affected by ventilation. This document contains information that has been used in preparing Appendix 1 of the Exploratory Studies Facility Design Requirements document for the Yucca Mountain Project.

Numerical results are presented for the Performance Assessment Calculational Exercise (PACE-90). One- and two-dimensional water and solute transport are presented for steady infiltration into Yucca Mountain. Evenly distributed infiltration rates of 0.01, 0.1, and 0.5 mm/yr were considered. The calculations of solute transport show that significant amounts of radionuclides can reach the water table over 100,000 yr at the 0.5 mm/yr rate. For time periods less than 10,000 yr or infiltrations less than 0.1 mm/yr very little solute reaches the water table. The numerical simulations clearly demonstrate that multi-dimensional effects can result in significant decreases in the travel time of solute through the modeled domain. Dual continuum effects are shown to be negligible for the low steady state fluxes considered. However, material heterogeneities may cause local amplification of the flux level in multi-dimensional flows. These higher flux levels may then require modeling of a dual continuum porous medium.

In support of the development of American National Standards Institute standards for the transport of radioactive materials, Sandia has a program to characterize the normal transport environment. This program includes both analytical modeling of package and trailer responses, and over-the-road tests to measure those responses. This paper presents the results of a series of over-the-road tests performed using Chem-Nuclear equipment in the Barnwell, SC, area. The test events included a variety of road types such as rough concrete, shock events such as railroad grade crossings, and driver responses such as sharp turns. The response of the package and trailer to these events was measured with accelerometers at various locations to determine the inertial loads. Either load cells or strain gages were used to measure tiedown response. These accelerations and loads were measured on systems with flexible and ``rigid`` tiedowns. The results indicated that while significant accelerations occur on the trailer bed, these do not translate into equivalent loads in either the package or the tiedown system. This indicates that trailer-bed response should not be used in determining the load factor for fatigue calculations of the package components or in determining design loads for tiedowns.

Currently, there are several Greater Confinement Disposal (GCD) boreholes at the Radioactive Waste Management Site (RWMS) for the Nevada Test Site. These are intermediate-depth boreholes used for the disposal of special case wastes, that is, radioactive waste within the Department of Energy complex that do not meet the criteria established for disposal of high-level waste, transuranic waste, or low-level waste. A performance assessment is needed to evaluate the safety of the GCD site, and to examine the feasibility of the GCD disposal concept as a disposal solution for special case wastes in general. This report documents the effort in defining all the waste inventory presently disposed of at the GCD site, and the inventory and release model to be used in a performance assessment for compliance with the Environmental Protection Agency`s 40 CFR 191.

The Faceted Stretched-Membrane Dish Program is part of a DOE-sponsored effort to develop a commercial 25 kWe dish/Stirling system employing a twelve-facet dish concentrator. The facets will utilize the stretched-membrane technology originated in the heliostat development program. Each facet is constructed with a thin metal membrane stretched over both sides of a steel ring. When a small vacuum is induced between the membranes they assume a parabolic contour capable of concentrating sunlight at a predetermined focal length. A reflective polymer film is attached to the face of the facet of the facet to enhance the optical performance. During Phase II of the Faceted Stretched-Membrane Dish Program, Science Applications International Corp. and Solar Kinetics, Inc., constructed prototype 3.5-meter facets utilizing different design approaches to demonstrate their manufacturability and optical performance. Sandia engaged in a program to determine the on-sun performance of the facets (for f/Ds of 2.7 to 3.0). A uniformly distributed slope error was used as the basis for comparison. Flux arrays based on slope error from a computer model were compared to a measured flux array for each facet. The slope error for the facet was determined by the value that would produce a modeled array with the minimum mean square difference to the measured array. The facet produced by SAIC demonstrated uniform slope errors of 2.2 to 3.0 milliradians with peak flux intesities of 334 to 416 kW/m{sup 2}. The SKI facet had slope errors of 1.6 to 1.9 milliradians with peak flux intesities of 543 to 1186 kW/m{sup 2}.

A 1-MeV neutron damage equivalence methodology and damage function have been developed for GaAs based on a recoil-energy dependent damage efficiency and the displacement kerma. This method, developed using life-time degradation in GaAs LEDs in a variety of neutron spectra, is also shown to be applicable to carrier removal. A validated methodology, such as this, is required to ensure and evaluate simulation fidelity in the neutron testing of GaAs semiconductors.

This report describes Welch's method for computing Power Spectral Densities (PSDs). We first describe the bandpass filter method which uses filtering, squaring, and averaging operations to estimate a PSD. Second, we delineate the relationship of Welch's method to the bandpass filter method. Third, the frequency domain signal-to-noise ratio for a sine wave in white noise is derived. This derivation includes the computation of the noise floor due to quantization noise. The signal-to-noise ratio and noise flood depend on the FFT length and window. Fourth, the variance the Welch's PSD is discussed via chi-square random variables and degrees of freedom. This report contains many examples, figures and tables to illustrate the concepts. 26 refs.

Four expert-judgment teams have developed analyses delineating possible future societies in the next 10,000 years in the vicinity of the Waste Isolation Pilot Plant (WIPP). Expert-judgment analysis was used to address the question of future societies because neither experimentation, observation, nor modeling can resolve such uncertainties. Each of the four, four-member teams, comprised of individuals with expertise in the physical, social, or political sciences, developed detailed qualitative assessments of possible future societies. These assessments include detailed discussions of the underlying physical and societal factors that would influence society and the likely modes of human-intrusion at the WIPP, as well as the probabilities of intrusion. Technological development, population growth, economic development, conservation of information, persistence of government control, and mitigation of danger from nuclear waste were the factors the teams believed to be most important. Likely modes of human-intrusion were categorized as excavation, disposal/storage, tunneling, drilling, and offsite activities. Each team also developed quantitative assessments by providing probabilities of various alternative futures, of inadvertent human intrusion, and in some cases, of particular modes of intrusion. The information created throughout this study will be used in conjunction with other types of information, including experimental data, calculations from physical principles and computer models, and perhaps other judgments, as input to performance assessment.'' The more qualitative results of this study will be used as input to another expert panel considering markers to deter inadvertent human intrusion at the WIPP.

A control algorithm is proposed for a molten-salt solar central receiver in a cylindrical configuration. The algorithm simultaneously regulates the receiver outlet temperature and limits thermal-fatigue damage of the receiver tubes to acceptable levels. The algorithm is similar to one that was successfully tested for a receiver in a cavity configuration at the Central Receiver Test Facility in 1988. Due to the differences in the way solar flux is introduced on the receivers during cloud-induced transients, the cylindrical receiver will be somewhat more difficult to control than the cavity receiver. However, simulations of a proposed cylindrical receiver at the Solar Two power plant have indicated that automatic control during severe cloud transients is feasible. This paper also provides important insights regarding receiver design and lifetime as well as a strategy for reducing the power consumed by the molten-salt pumps. 14 refs., 7 figs., 2 tabs.

This paper summarizes the results of aging, condition monitoring, and accident testing of Class 1E cables used in nuclear power generating stations. Three sets of cables were aged for up to 9 months under simultaneous thermal ({approx_equal} 100{degrees}C) and radiation ({approx_equal}0.10 kGy/hr) conditions. After the aging, the cables were exposed to a simulated accident consisting of high dose rate irradiation ({approx_equal}6 kGy/hr) followed by a high temperature steam exposure. A fourth set of cables, which were unaged, were also exposed to the accident conditions. The cables that were aged for 3 months and then accident tested were subsequently exposed to a high temperature steam fragility test (up to 400{degrees}C), while the cables that were aged for 6 months and then accident tested were subsequently exposed to a 1000-hour submergence test in a chemical solution. The results of the tests indicate that the feasibility of life extension of many popular nuclear power plant cable products is promising and that mechanical measurements (primarily elongation, modulus, and density) were more effective than electrical measurements for monitoring age-related degradation. In the high temperature steam test, ethylene propylene rubber (EPR) cable materials generally survived to higher temperatures than crosslinked polyolefin (XLPO) cable materials. In dielectric testing after the submergence testing, the XLPO materials performed better than the EPR materials. This paper presents some recent experimental data that are not yet available elsewhere and a summary of findings from the entire experimental program.

Reflux solar receivers for dish-Stirling electric power generation systems are currently being investigated by several companies and laboratories. In support of these efforts, the AEETES thermal performance numerical model has been developed to predict thermal performance of pool-boiler and heat-pipe reflux receivers. The formulation of the AEETES numerical model, which is applicable to axisymmetric geometries with asymmetric incident fluxes, is presented in detail. Thermal efficiency predictions agree to within 4.1% with test data from on-sun tests of a pool-boiler reflux receiver. Predicted absorber and sidewall temperatures agree with thermocouple data to within 3.3.% and 7.3%, respectively. The importance of accounting for the asymmetric incident fluxes is demonstrated in comparisons with predictions using azimuthally averaged variables. The predicted receiver heat losses are characterized in terms of convective, solar and infrared radiative, and conductive heat transfer mechanisms. 27 refs., 9 figs., 4 tabs.

Combustion of energetic materials involves processes in both gas and condensed phases and is governed by coupled thermal, physical, and chemical phenomena. Development of reliable models for design, performance, stability, and hazard analyses requires detailed understanding of three general chemical reaction regimes: (1) initial condensed-phase decomposition, (2) subsequent interaction of decomposition products with the remaining condensed phase, and (3) gas-phase reaction of decomposition products to form the ultimate combustion products. The first two regimes are the least understood and most difficult to study, particularly the initial condensed-phase decomposition. The basic difficulty in studying condensed phase phenomena has been the inability to probe directly chemistry in the condensed phase under isothermal condition and with the spatial and temporal resolution needed at higher temperatures and reaction rates. Thin-film samples provide a means to study condensed-phase chemistry at isothermal conditions and with microsecond temporal resolution. We are developing an experiment system that employs rapidly heated thin- film samples and multiple diagnostics to examine condensed-phase chemistry and monitor evolved gas species. Results from our initial work have been encouraging. Thin-film samples of several energetic materials have been prepared and appear to be representative of bulk materials. Furthermore, preliminary experiments indicate that all the use of these samples with two chemical diagnostic techniques, time-of- flight mass spectrometry (TOFMS) and time-resolved infrared spectral photography (TRISP), is viable. 5 refs., 8 figs.

We are studying the kinetics of singlet oxygen ({sup 1}{Delta}{sub g}O{sub 2}) in solid polymers by monitoring its phosphorescence in time-resolved experiments. In macromolecular matrices where {sup 1}{Delta}{sub g}O{sub 2} is produced by energy transfer from a photosensitizer, {sup 1}{Delta}{sub g}O{sub 2} lifetimes can be obtained by deconvoluting the {sup 1}{Delta}{sub g}O{sub 2} sensitizer kinetics from the {sup 1}{Delta}{sub g}O{sub 2} phosphorescence signal. The sensitizer kinetics can be obtained in a flash absorption experiment. These time-resolved techniques have been utilized to examine the interaction of {sup 1}{Delta}{sub g}O{sub 2} in polymers with two types of additives: (1) molecules capable of undergoing chemical reactions with {sup 1}{Delta}{sub g}O{sub 2} (reactive quenchers) and (2) molecules capable of quenching {sup 1}{Delta}{sub g}O{sub 2} to its ground triplet state (physical quenchers). From this study we have determined directly that significant reactive and physical quenching of {sup 1}{Delta}{sub g}O{sub 2} are possible in a solid polymer. The polymer matrix greatly reduces the quenching rate of a very efficient quencher and slightly elevates the quenching rate of inefficient quenchers, as compared with rates determined in analogous liquids. This compressed range of quenching efficiencies has implications for understanding photodegradation and stabilization of polymers. 12 refs., 3 figs., 1 tab.

The eutectic Sn-Pb solder alloy is discussed with respect to alloy development options to improve the thermomechanical fatigue behavior of solder joints. Eutectic Sn-Pb solder joints fail through the development of a heterogeneous coarsened band of recrystallized and coarsened Pb- and Sn-rich phases. All imposed deformation concentrates solely into this thin region, accelerating fatigue failures. The development of solder alloys is currently being undertaken to improve the fatigue characteristics of eutectic Sn-Pb solder. New alloys must retain wetting and manufacturability characteristics similar to eutectic Sn-Pb. The options discussed to improve fatigue life include: creating a fine superplastic microstructure, small alloy additions to homogenize the microstructure, carbon reinforced composite solder, dispersed second phase precipitates that break up the solder microstructure, and using different solder alloys to replace eutectic Sn-Pb.

The polarimetry problem (the measurement of the radar-cross-section polarization scattering matrix) is described. Two methods of calibrating a polarimetric radar are outlined. The first is a general multiple-calibration-target (MCT) method applicable to almost any radar system. The second is a simple, single-calibration-target (SCT) method applicable to systems which use a single antenna for both transmit/receive and a reciprocal RF network. The performance of the MCT method is examined through the use of Monte Carlo simulations. Finally, the SCT method is applied to measurements from the SCATTER facility, demonstrating about 40 dB isolation between polarization components in the frequency domain and in excess of 50 dB in the range domain.