Publications

A sinkhole discovered over the edge of the Strategic Petroleum Reserve storage facility at Weeks Island salt dome, Louisiana, led to decommissioning the site during 1995--1998, following extensive diagnostics in 1994. The sinkhole resulted from mine-induced fractures in the salt which took may years to develop, eventually causing fresh water to leak into the storage chamber and dissolve the overlying salt, thus causing overburden collapse into the void. Prior to initiating the oil removal, a freeze wall was constructed at depth around the sinkhole in 1995 to prevent water inflow; a freeze plug will remain in place until the mine is backfilled with brine in 1997--8, and stability is reached. Residual oil will be removed; environmental monitoring has been initiated and will continue until the facility is completely plugged and abandoned, and environmental surety is achieved.

The technology base for Repetitive High Energy Pulsed Power (RHEPP) was originally developed to support defense program applications. As RHEPP technology matures, its potential for use in commercial applications can be explored based on inherent strengths of high average power, high dose rate, cost efficient scaling with power, and potential for long life performance. The 300 kW, 2 MeV RHEPP II accelerator is now in operation as a designated DOE User Facility, exploring applications where high dose-rate (> 10{sup 8} Gy/s) may be advantageous, or very high average power is needed to meet throughput requirements. Material surface and bulk property modification, food safety, and large-scale timber disinfestation are applications presently under development. Work is also in progress to generate the reliability database required for the design of 2nd generation systems.

We studied whether plasma-etching techniques can use screen printed gridlines as etch masks to form self-aligned, patterned-emitter profiles on multicrystalline silicon (mc-Si) cells from Solarex Our initial results found a statistically significant improvement of about half an absolute percentage point m cell efficiency when the self-aligned emitter etchback was combined with a PECVD-nitride surface passivation treatment. Some additional improvement in bulk diffusion length was observed when a hydrogen passivation treatment was used in the process. We attempted to gain additional benefits from using an extra-heavy phosphorus emitter diffusion before the gridlines were deposited. However, this required a lusher plasma-etch power to etch back the deeper diffusion and keep the etch time reasonably short. The higher power etch may have damaged the surface and the gridlines so that improvement due to surface passive and reduced gridline contact resistance was inhibited.

Sandia National Laboratories has found that the reliability and failure modes of current-generation network technologies can be effectively modeled using fault tree-based probabilistic logic modeling (PLM) techniques. We have developed fault tree models that include various hierarchical networking technologies and classes of components interconnected in a wide variety of typical and atypical configurations. In this paper we discuss the types of results that can be obtained from PLMs and why these results are of great practical value to network designers and analysts. After providing some mathematical background, we describe the `plug-and-play` fault tree analysis methodology that we have developed for modeling connectivity and the provision of network services in several current- generation network architectures. Finally, we demonstrate the flexibility of the method by modeling the reliability of a hybrid example network that contains several interconnected ethernet, FDDI, and token ring segments. 11 refs., 3 figs., 1 tab.

Production of a full-size divertor cassette involves eight major components. All of the components are mounted on the cassette body. Inner divertor channel components for the vertical target design are being provided by the Japan Home Team. Outer divertor channel components for the vertical target design are being provided by the European and United States Home Teams. Gas box liners are being provided by the Russian Home Team. The full-size components manufactured by the four parties will be shipped to the US Home Team for assembly into a full size divertor cassette. The techniques for assembly and maintenance of the cassette will be demonstrated during this process. The assembled cassette will be tested for proper flow distribution and proof of the filling and draining procedures. The testing will include vacuum leak tightness at full temperature and pressure, cyclic heating to 150 {degrees}C, verification of dimensional accuracy of the assembled components, and application of thermal gradients to measure dimensional stability. The development of the divertor for the International Thermonuclear Experimental Reactor (ITER) depends on successful R&D efforts on materials, joining, and plasma materials interactions. Results of the development program are presented. The scale-up of the processes developed in the basic research and development tasks is accomplished by producing and high-heat-flux testing medium and full-scale mock- ups. The design of the mock-ups is discussed.

ITER will be the first tokamak having long pulse operation using deuterium-tritium fuel. The problem of designing heat removal structures for steady state in a neutron environment is a major technical goal for the ITER Engineering Design Activity (EDA). The steady state heat flux specified for divertor components is 5 MW/m{sup 2} for normal operation with transients to 15 MW/m{sup 2} for up to 10 s. The selection of materials for plasma facing components is one of the major research activities. Three materials are being considered for the divertor; carbon fiber composites, beryllium, and tungsten. This paper discusses the relative advantages and disadvantages of these materials. The final section of plasma facing materials for the ITER divertor will not be made until the end of the EDA.

This report summarizes available data on ground motions from underground nuclear explosions recorded on and near the Nevada Test Site, with emphasis on the ground motions recorded at stations on Yucca Mountain, the site of a potential high-level radioactive waste repository. Sandia National Laboratories, through the Weapons Test Seismic Investigations project, collected and analyzed ground motion data from NTS explosions over a 14-year period, from 1977 through 1990. By combining these data with available data from earlier, larger explosions, prediction equations for several ground motion parameters have been developed for the Test Site area for underground nuclear explosion sources. Also presented are available analyses of the relationship between surface and downhole motions and spectra and relevant crustal velocity structure information for Yucca Mountain derived from the explosion data. The data and associated analyses demonstrate that ground motions at Yucca Mountain from nuclear tests have been at levels lower than would be expected from moderate to large earthquakes in the region; thus nuclear explosions, while located relatively close, would not control seismic design criteria for the potential repository.

Sandia National Laboratories is operated for the United States Department of Energy by a subsidiary of Lockheed Martin Corporation. National security programs and defense-related environmental programs for DOE comprise 65 percent of Sandia`s work. We are the DOE Defense Programs laboratory responsible for engineering development of all US nuclear weapons and for systems integration of the nuclear weapons with their delivery vehicles. Our responsibilities include design, certification, and assessment of the nonnuclear subsystems of nuclear weapons; safety, security, reliability, and use control; issues associated with production and dismantlement of nuclear weapons; surveillance and support of weapons in the stockpile; and work in nuclear intelligence, nonproliferation, and treaty verification technologies. Sandia is a multiprogram laboratory. Ten percent of our work supports DOE missions in energy science, research, and development. When appropriate, we also perform work for other government agencies, particularly the Department of Defense, in programs where unique competencies built our mission responsibilities can add value. This report discusses the activities of these responsibilities at the Sandia National Laboratories.

Icarus is a 2D Direct Simulation Monte Carlo (DSMC) code which has been optimized for the parallel computing environment. The code is based on the DSMC method of Bird and models from free-molecular to continuum flowfields in either cartesian (x, y) or axisymmetric (z, r) coordinates. Computational particles, representing a given number of molecules or atoms, are tracked as they have collisions with other particles or surfaces. Multiple species, internal energy modes (rotation and vibration), chemistry, and ion transport are modelled. A new trace species methodology for collisions and chemistry is used to obtain statistics for small species concentrations. Gas phase chemistry is modelled using steric factors derived from Arrhenius reaction rates. Surface chemistry is modelled with surface reaction probabilities. The electron number density is either a fixed external generated field or determined using a local charge neutrality assumption. Ion chemistry is modelled with electron impact chemistry rates and charge exchange reactions. Coulomb collision cross-sections are used instead of Variable Hard Sphere values for ion-ion interactions. The electrostatic fields can either be externally input or internally generated using a Langmuir-Tonks model. The Icarus software package includes the grid generation, parallel processor decomposition, postprocessing, and restart software. The commercial graphics package, Tecplot, is used for graphics display. The majority of the software packages are written in standard Fortran.

Intelligent, agile manufacturing relies on automated programming of digitally controlled processes. Currently, processes such as Computer Numerically Controlled (CNC) machining are difficult to automate because of highly restrictive controllers and poor software environments. It is also difficult to utilize sensors and process models for adaptive control, or to integrate machining processes with other tasks within a factory floor setting. As part of a Laboratory Directed Research and Development (LDRD) program, a CNC machine control system architecture based on object-oriented design and graphical programming has been developed to address some of these problems and to demonstrate automated agile machining applications using platform-independent software.

A growing demand exists for inexpensive and reliable sensors for moisture detection in reduced pressure processing environments. Sandia`s Porous Silicon Capacitor (PSC) sensor appears to be an ideal candidate for this application. This sensor is a solid state device that detects moisture through changes in dielectric constant with water adsorption. Standard microelectronic fabrication techniques are used in its production affording low cost production and ready integration into complex sensor and electronic arrays. This sensor has previously been investigated for moisture detection in fluid streams, however, little effort has been placed on its behavior in a vacuum environment. Sandia`s Sensors in Vacuum (SIV) test facility has been employed to evaluate the performance characteristics of this sensor in vacuum. In addition, a vacuum-based study allows for a more controlled environment in which the intrinsic lower limit for moisture detection and response times to moisture changes can be easily determined quantitatively. This report describes the performance characteristics of a series of sensors from a single production lot. Calibration of these sensors to moisture levels from part per billion to part per hundred concentrations has been performed. The concentration-dependent sensitivity of these sensors is documented. The response time and drift characteristics of these sensors are also discussed. The investigation of a preliminary method for increasing the recovery time of the sensor after moisture exposure is presented. The role of hydrocarbon contamination, a potential problem in some vacuum schemes, is also evaluated. Specific recommendations are made on how to implement this sensor for vacuum applications.

This work was performed jointly by Sandia National Laboratories (Albuquerque, NM) and Siemens Solar Industries (Camarillo, CA) under a Cooperative Research and Development Agreement (CRADA 1248). The work covers the period May 1994 to March 1996. The purpose of the work was to explore the performance potential of commercial, photovoltaic-grade Czochralski (Cz) silicon, and to demonstrate this potential through fabrication of high-efficiency cells and a module. Fabrication of the module was omitted in order to pursue further development of advanced device structures. The work included investigation of response of the material to various fabrication processes, development of advanced cell structures using the commercial material, and investigation of the stability of Cz silicon solar cells. Some important achievements of this work include the following: post-diffusion oxidations were found to be a possible source of material contamination; bulk lifetimes around 75 pts were achieved; efficiencies of 17.6% and 15.7% were achieved for large-area cells using advanced cell structures (back-surface fields and emitter wrap-through); and preliminary investigations into photodegradation in Cz silicon solar cells found that oxygen thermal donors might be involved. Efficiencies around 20% should be possible with commercial, photovoltaic-grade silicon using properly optimized processes and device structures.

Gemini is the coupling of Icarus, the Sandia National Laboratories (SNL) 2-D Direct Simulation Monte Carlo (DMSC) code, to MPRES, the University of Houston 2-D finite element plasma reactor code. Thus, Gemini is not a stand alone code. The primary application of Gemini is the simulation of inductively coupled plasma reactors that operate at low pressures (< 10mtorr) where continuum formulations of the transport equations begin to break down. Plasma parameters (electron density (ne), electron temperature (Te) and electrostatic fields (Er and Ez)) are computed in MPRES and interpolated onto the DSMC grid. This allows transport of the neutrals and ions to be performed using the DSMC method while including electron impact reactions and field transport effects. A sample calculation including appropriate input files is given.

This report presents, Aspen. Sandia National Laboratories is developing this new agent-based microeconomic simulation model of the U.S. economy. The model is notable because it allows a large number of individual economic agents to be modeled at a high level of detail and with a great degree of freedom. Some features of Aspen are (a) a sophisticated message-passing system that allows individual pairs of agents to communicate, (b) the use of genetic algorithms to simulate the learning of certain agents, and (c) a detailed financial sector that includes a banking system and a bond market. Results from runs of the model are also presented.

This report presents a summary of the major results from a program to develop a manufacturable, high-efficiency silicon concentrator solar cell and a cost-effective manufacturing facility. The program was jointly funded by the Electric Power Research Institute, Sandia National Laboratories through the Concentrator Initiative, and SunPower Corporation. The key achievements of the program include the demonstration of 26%-efficient silicon concentrator solar cells with design-point (20 W/cm{sup 2}) efficiencies over 25%. High-performance front-surface passivations; that were developed to achieve this result were verified to be absolutely stable against degradation by 475 days of field exposure at twice the design concentration. SunPower demonstrated pilot production of more than 1500 of these cells. This cell technology was also applied to pilot production to supply 7000 17.7-cm{sup 2} one-sun cells (3500 yielded wafers) that demonstrated exceptional quality control. The average efficiency of 21.3% for these cells approaches the peak efficiency ever demonstrated for a single small laboratory cell within 2% (absolute). Extensive cost models were developed through this program and calibrated by the pilot-production project. The production levels achieved indicate that SunPower could produce 7-10 MW of concentrator cells per year in the current facility based upon the cell performance demonstrated during the program.

Spotlight synthetic aperture radar images can be formed from the complex phase history data using two main techniques: (1) polar-to-cartesian interpolation followed by two-dimensional inverse Fourier transform (2DFFT), and (2) convolution backprojection (CBP). CBP has been widely used to reconstruct medical images in computer aided tomography, and only recently has been applied to form synthetic aperture radar imagery. It is alleged that CBP yields higher quality images because (1) all the Fourier data are used and (2) the polar formatted data is used directly to form a 2D Cartesian image and therefore 2D interpolation is not required. This report compares the quality of images formed by CBP and several modified versions of the 2DFFT method. We show from an image quality point of view that CBP is equivalent to first windowing the phase history data and then interpolating to an exscribed rectangle. From a mathematical perspective, we should expect this conclusion since the same Fourier data are used to form the SAR image. We next address the issue of parallel implementation of each algorithm. We dispute previous claims that CBP is more readily parallelizable than the 2DFFT method. Our conclusions are supported by comparing execution times between massively parallel implementations of both algorithms, showing that both experience similar decreases in computation time, but that CBP takes significantly longer to form an image.

The increased power of computers and computer codes makes the use of nonlinear dynamic finite element analyses attractive for use as a tool used in the design and certification of radioactive material transportation packages. For this analysis technique to be acceptable it must be demonstrated. The technique has the ability to accurately capture the response of the packages to accident environments required by the regulations. The best method of demonstrating this ability is via a series of benchmark analyses. In this paper three benchmark problems involving significant inelastic deformations will be discussed. One of the problems has been analyzed using many different finite element codes. The other two problems involve comparison of finite element calculations to the results form physical tests. The ability of the finite element method to accurately capture the response in these three problems indicates the method should be acceptable for radioactive material transportation package design and certification.

An acoustic emission tester for aircraft Halon bottles has been developed. The necessary load is applied by heating the bottles. Acoustic emission is monitored during the heating by six sensors held in position by a special fixture. This fixture was designed to fit spheres with diameters between 5 and 16 inches. A prototype has been undergoing testing in two commercial Halon bottle repair and test facilities. Results to date indicate that about 97 percent of the bottles tested show no indications of any flaws. The other three percent have had indications of flaws in non-critical areas of the bottles. All bottles tested to date have passed the hydrostatic test required by the Department of Transportation (DOT).

The development of smaller circuit volumes in microelectronic applications, particularly Multichip Module (MCM) technology, entails deposition of minute quantities of solder, with volumes on the order of nanoliters. We propose a system for fluxless solder deposition which uses on-demand solder jetting for deposition of 200 micrometer diameter solder droplets onto aluminum pads. This work details the computational modeling performed to provide design parameters for a magneto-hydrodynamic solder jetter (MHD). A dimensionless analysis was used to relate the fluid properties, the orifice length and width, and the droplet size to the amplitude and duration of the pressure pulse. These results were used as the initial inputs for the fluid dynamics model, and subsequent iterations were performed to determine the operational parameters that lead to the formation of stable, single droplets. Results show that a maximum pulse amplitude on the order of 0.5 Mdynes/cm[sup 2] is necessary to dispense molten solder from a 200 micrometer diameter orifice. The size of the droplet was found to vary linearly with the applied pressure pulse. The duration of the pulse ranged from approximately 0.6 to 0.9 milliseconds. A theoretical description of the relationship between the orifice diameter, surface tension, and `Pinch-off` time is given, and is in agreement with the results of the computational model.

Field sampling and rapid gas analysis techniques were used to survey near-surface soil gases for geotechnical diagnostic purposes at the Weeks Island Strategic Petroleum Reserve (SPR) site and other salt dome locations in southern Louisiana. This report presents the complete data, results and interpretations obtained during 1995. Weeks Island 1994 gas survey results are also briefly summarized; this earlier study did not find a definitive correlation between sinkhole No. 1 and soil gases. During 1995, several hundred soil gas samples were obtained and analyzed in the field by gas chromatography, for profiling low concentrations and gas anomalies at ppm to percent levels. The target gases included hydrogen, methane, ethane and ethylene. To supplement the field data, additional gas samples were collected at various site locations for laboratory analysis of target gases at ppb levels. Gases in the near-surface soil originate predominantly from the oil, from petrogenic sources within the salt, or from surface microbial activity. Surveys were conducted across two Weeks Island sinkholes, several mapped anomalous zones in the salt, and over the SPR repository site and its perimeter. Samples were also taken at other south Louisiana salt dome locations for comparative purposes. Notable results from these studies are that elevated levels of hydrogen and methane (1) were positively associated with anomalous gassy or shear zones in the salt dome(s) and (2) are also associated with suspected salt fracture (dilatant) zones over the edges of the SPR repository. Significantly elevated areas of hydrogen, methane, plus some ethane, were found over anomalous shear zones in the salt, particularly in a location over high pressure gas pockets in the salt, identified in the mine prior to SPR operations. Limited stable isotope ratio analyses, SIRA, were also conducted and determined that methane samples were of petrogenic origin, not biogenic.

Three issues concerning phonon-assisted hopping in molecularly doped polymers are considered. The first issue is whether Arrhenius jump rates in the vicinity of room temperature arise from single- phonon or small-polaronic hopping. It is concluded that Arrhenius hopping only occurs above low temperatures through small-polaronic hopping. Second, hopping in molecularly doped polymers is compared with small- polaronic hopping of other systems. Small-polaronic hopping typically occurs between similar chemical structures whose energies are relatively insensitive to their surroundings. Thus, disorder energies experienced by carriers are often modest, values of several hundredths of an eV are common. Nonetheless, the effects of large electric fields on carrier mobilities differ significantly among disordered systems. Data reported for molecularly doped polymers is unlike that for either transition- metal-oxide or chalcogenide glasses. In no case is high-field transport well understood. Finally, I stress that steady-state flow is driven by differences in sites` quasielectrochemical potentials (QECPs). With disorder, differences of QECPs are not simply related to the driving emf. Solution of the (nonlinear) stochastic equations for the QECPs shows that bottlenecks produced by disorder result in nonohmic conduction. Solving the linearized stochastic (disordered resistor network) equations underestimates bottleneck effects. Linearization is inappropriate when interest differences in the QECPs exceed [kappa]T.

Chemometric multivariate calibration methods are rapidly impacting quantitative infrared spectroscopy in many positive ways. The combination of vibrational spectroscopy and chemometrics has been used by industry for quality control and process monitoring. The growth of these methods has been phenomenal in the past decade. Yet, as with any new technology, there are growing pains. The methods are so powerful at finding correlations in the data, that when used without great care they can readily yield results that are not valid for the analysis of future unknown samples. In this paper, the power of the multivariate calibration methods is discussed while pointing out common pitfalls and some remaining challenges that may slow the implementation of chemometrics in research and industry.

An Electrorheological fluid is normally a low-viscosity colloidal suspension, but when an electric field is applied, the fluid undergoes a reversible transition to a solid, being able to support considerable stress without yield. Commercial possibilities for such fluids are enormous, including clutches, brakes, valves,shock absorbers, and stepper motors. However, performance of current fluids is inadequate for many proposed applications. Our goal was to engineer improved fluids by investigating the key technical issues underlying the solid-phase yield stress and the liquid to solid switching time. Our studies focused on field-induced interactions between colloidal particles that lead to solidification, the relation between fluid structure and performance (viscosity, yield stress), and the time evolution of structure in the fluid as the field is switched on or off.

A suite of MATLAB-based code modules has been developed to provide optimal weld schedules, regulating weld process parameters for C0[sub 2] and pulse ND:YAG laser welding methods, and arc welding in support of the Smartweld manufacturing initiative. The optimization methodology consists of mixed genetic and gradient-based algorithms to query semi-empirical, nonlinear algebraic models. The optimization output provides heat-input-efficient welds for user-specified weld dimensions. User querying of all weld models is available to examine sub-optimal schedules. In addition, a heat conduction equation solver for 2-D heat flow is available to provide the user with an additional check of weld thermal effects. The inclusion of thermodynamic properties allows the extension of the empirical models to include materials other than those tested. All solution methods are provided with graphical user interfaces and display pertinent results in two and three-dimensional form. The code architecture provides an extensible framework to add an arbitrary number of modules.

Drill hole USW SD-9 is one of several holes drilled under Site Characterization Plan Study as part of the characterization program at Yucca Mountain, Nevada, which has been proposed as the potential location of a repository for high-level nuclear waste. The SD-9 drill hole is located in the northern part of the potential repository area. Quantitative and semiquantitative data are included in this report for cover recovery, rock-quality designation (RQD), lithophysal cavity abundance, and fracturing. These data are spatially variable, both within and among the major formational-level stratigraphic units. Nonwelded intervals in general exhibit higher recoveries and more intact (higher) RQD values than welded intervals. The most intact, highest-RQD materials encountered within the Topopah Spring belong to the lower 33.3 ft of the middle nonlithophysal zone. This report includes quantitative data for the framework material properties of porosity, bulk and particle density, and saturated hydraulic conductivity. Graphical analysis of variations in these laboratory hydrologic properties indicates first-order control of material properties by the degree of welding and the presence of zeolite minerals. Many major lithostratigraphic contacts are not well expressed in the material-property profiles; contacts of material-property units are related more to changes in the intensity of welding. Approximate in-situ saturation data of samples preserved immediately upon recovery from the hole are included in the data tabulation.

By predicting the total life-cycle cost of owning and operating production equipment, it becomes possible for processors to make accurate and intelligent decisions regarding major capitol equipment investments as well as determining the most cost effective manufacturing processes and environments. Cost of Ownership (COO) is a decision making technique based on inputting the total costs of acquiring, operating and maintaining production equipment. All quantitative economic and production data can be modeled and processed using COO software programs such as the Cost of Ownership Luminator program TWO COOL{trademark}. This report investigated the Cost of Ownership differences between the current state-of-the-art solder ball attachment process and a prototype solder jetting process developed by Sandia National Laboratories. The prototype jetting process is a novel and unique approach to address the anticipated high rate ball grid array (BGA) production requirements currently forecasted for the next decade. The jetting process, which is both economically and environmentally attractive eliminates the solder sphere fabrication step, the solder flux application step as well as the furnace reflow and post cleaning operations.

A comprehensive collection of scenarios is presented that connect initiating tectonic events with radionuclide releases by logical and physically possible combinations or sequences of features, events and processes. The initiating tectonic events include both discrete faulting and distributed rock deformation developed through the repository and adjacent to it, as well as earthquake-induced ground motion and changes in tectonic stress at the site. The effects of these tectonic events include impacts on the engineered-barrier system, such as container rupture and failure of repository tunnels. These effects also include a wide range of hydrologic effects such as changes in pathways and flow rates in the unsaturated and saturated zones, changes in the water-table configuration, and in the development of perched-water systems. These scenarios are intended go guide performance-assessment analyses and to assist principal investigators in how essential field, laboratory, and calculational studies are used. This suite of scenarios will help ensure that all important aspects of the system disturbance related to a tectonic scenario are captured in numerical analyses. It also provides a record of all options considered by project analysts to provide documentation required for licensing agreement. The final portion of this report discusses issues remaining to be addressed with respect to tectonic activity. 105 refs.

Smoke can adversely affect digital electronics; in the short term, it can lead to circuit bridging and in the long term to corrosion of metal parts. This report is a summary of the work to date and component-level tests by Sandia National Laboratories for the Nuclear Regulatory Commission to determine the impact of smoke on digital instrumentation and control equipment. The component tests focused on short-term effects such as circuit bridging in typical components and the factors that can influence how much the smoke will affect them. These factors include the component technology and packaging, physical board protection, and environmental conditions such as the amount of smoke, temperature of burn, and humidity level. The likelihood of circuit bridging was tested by measuring leakage currents and converting those currents to resistance in ohms. Hermetically sealed ceramic packages were more resistant to smoke than plastic packages. Coating the boards with an acrylic spray provided some protection against circuit bridging. The smoke generation factors that affect the resistance the most are humidity, fuel level, and burn temperature. The use of CO{sub 2} as a fire suppressant, the presence of galvanic metal, and the presence of PVC did not significantly affect the outcome of these results.

Findings from a four-year study by an international benchmarking group in the comparison of computational methods for evaluating burnup credit in criticality safety analyses are presented in this paper. Approximately 20 participants from 11 countries have provided results for most problems. Four detailed benchmark problems for Pressurized Water Reactor (PWR) fuel have been completed and are summarized in this paper. Preliminary results from current work addressing burnup credit for Boiling Water Reactor (BWR) fuel will also be discussed as well as planned activities for additional benchmarks including Mixed-Oxide (MOX) fuels, subcritical benchmarks, international databases, and other activities.

No abstract available.

The U.S. Department of Energy`s (DOE) Yucca Mountain Site Characterization Project (YMP) is studying Yucca Mountain in southwestern Nevada as a potential site for a high-level nuclear waste repository. Site characterization will be facilitated by the construction of an Exploratory Studies Facility (ESF). The ESF and potential repository will be excavated from both nonwelded and welded ashflow tuff with varying rock quality (degree of welding, rock mass strength, etc.) and fault and fracture characteristics. Design concerns for the construction of these facilities include the integrity of the structure during underground testing operations and, if it occurs, the emplacement and storage of high-level nuclear waste which could increase the local temperatures in the underground rock mass to as high as 300{degrees}C. Because of the associated issues regarding personnel and long-term environmental safety, sophisticated jointed rock mass models will be required to provide a high degree of confidence for decisions regarding the design, site characterization, and licensing of such facilities. The objective of the work documented in this report is to perform code validation calculations for three rock-mass computer models. The three rock-mass computer models used for this report are the discrete element code UDEC, Version 1.82; and the finite element continuum joint models JAC2D Version 5.10 and JAS3D Version 1.1. The rock mass behavior predicted by the models are compared to the results of laboratory experiments on layered polycarbonate (Lexan) and granite plate experiments. These experiments examine the rock mass behavior of well-defined jointed rock structures or models of jointed structures under uniaxial and biaxial loading. The laboratory environment allows control over the boundary conditions, material properties, and quality and quantity of the data obtained.

This report describes activities completed in August 1996 under a Cooperative Research and Development Agreement (CRADA) between Sandia National Laboratories and General Motors which began in April 1993 and was later expanded in January 1994 to include Ford and Chrysler under the Low Emission Partnership (LEP). The tasks within this effort (CRADA SC93/01155) included the evaluation of hydrous metal oxide materials as catalyst supports for the abatement of nitrogen oxides in lean-burn automotive exhaust catalyst applications.

Fracture and matrix properties in a sequence of unsaturated, welded tuffs at Yucca Mountain, Nevada, are modeled in two-dimensional cross-sections through geostatistical simulation. In the absence of large amounts of sample data, an n interpretive, deterministic, stratigraphic model is coupled with a gaussian simulation algorithm to constrain realizations of both matrix porosity and fracture frequency. Use of the deterministic, stratigraphic model imposes scientific judgment, in the form of a conceptual geologic model, onto the property realizations. Linear coregionalization and a regression relationship between matrix porosity and matrix hydraulic conductivity are used to generate realizations of matrix hydraulic conductivity. Fracture-frequency simulations conditioned on the stratigraphic model represent one class of fractures (cooling fractures) in the conceptual model of the geology. A second class of fractures (tectonic fractures) is conceptualized as fractures that cut across strata vertically and includes discrete features such as fault zones. Indicator geostatistical simulation provides locations of this second class of fractures. The indicator realizations are combined with the realizations of fracture spacing to create realizations of fracture frequency that are a combination of both classes of fractures. Evaluations of the resulting realizations include comparing vertical profiles of rock properties within the model to those observed in boreholes and checking intra-unit property distributions against collected data. Geostatistical simulation provides an efficient means of addressing spatial uncertainty in dual continuum rock properties.

Advantages in transient ionizing and single-event upset (SEU) radiation hardness of silicon-on-insulator (SOI) technology spurred much of its early development. Both of these advantages are a direct result of the reduced charge collection volume inherent to SOI technology. The fact that SOI transistor structures do not include parasitic n-p-n-p paths makes them immune to latchup. Even though considerable improvement in transient and single-event radiation hardness can be obtained by using SOI technology, there are some attributes of SOI devices and circuits that tend to limit their overall hardness. These attributes include the bipolar effect that can ultimately reduce the hardness of SOI ICs to SEU and transient ionizing radiation, and charge buildup in buried and sidewall oxides that can degrade the total-dose hardness of SOI devices. Nevertheless, high-performance SOI circuits can be fabricated that are hardened to both space and nuclear radiation environments, and radiation-hardened systems remain an active market for SOI devices. The effects of radiation on SOI MOS devices are reviewed.

In 1991, the Department of Energy initiated the Advanced Liquefaction Concepts Program to promote the development of new and emerging technology that has potential to reduce the cost of producing liquid fuels by direct coal liquefaction. Laboratory research performed by researchers at CAER, CONSOL, Sandia, and LDP Associates in Phase I is being developed further and tested at the bench scale at HTI. HTI Run ALC-1, conducted in the spring of 1996, was the first of four planned tests. In Run ALC-1, feed coal ash reduction (coal cleaning) by oil agglomeration, and recycle solvent quality improvement through dewaxing and hydrotreatment of the recycle distillate were evaluated. HTI`s bench liquefaction Run ALC-1 consisted of 25 days of operation. Major accomplishments were: 1) oil agglomeration reduced the ash content of Black Thunder Mine coal by 40%, from 5.5% to 3.3%; 2) excellent coal conversion of 98% was obtained with oil agglomerated coal, about 3% higher than the raw Black Thunder Mine coal, increasing the potential product yield by 2-3% on an MAF coal basis; 3) agglomerates were liquefied with no handling problems; 4) fresh catalyst make-up rate was decreased by 30%, with no apparent detrimental operating characteristics, both when agglomerates were fed and when raw coal was fed (with solvent dewaxing and hydrotreating); 5) recycle solvent treatment by dewaxing and hydrotreating was demonstrated, but steady-state operation was not achieved; and 6) there was some success in achieving extinction recycle of the heaviest liquid products. Performance data have not been finalized; they will be available for full evaluation in the new future.

Systems and devices that are controlled remotely are becoming more common in security systems in the US Air Force and other government agencies to provide protection of valuable assets. These systems reduce the number of needed personnel while still providing a high level of protection. However, each remotely controlled device usually has its own communication protocol. This limits the ability to change devices without changing the system that provides the communications control to the device. Sandia is pursuing a standard protocol that can be used to communicate with the different devices currently in use, or may be used in the future, in the US Air Force and other government agencies throughout the security community. Devices to be controlled include intelligent pan/tilt mounts, day/night video cameras., thermal imaging cameras, and remote data processors. Important features of this protocol include the ability to send messages of varying length, identify the sender, and more importantly, control remote data processors. As camera and digital signal processor (DSP) use expands, the DSP will begin to reside in the camera itself. The DSP can be used to provide auto-focus, frame-to- frame image registration, video motion detection (VMD), target detection, tracking, image compression, and many other functions. With the serial data control link, the actual DSP software can be updated or changed as required. Coaxial video cables may become obsolete once a compression algorithm is established in the DSP. This paper describes the proposed public domain protocol, features, and examples of use. The authors hope to elicit comments from security technology developers regarding format and use of remotely controlled automated assessment devices. 2 figs., 1 tab.

A {ital q}-vector of responses, y, is related to a {ital p}-vector of explanatory variables, x, through a causal linear model. In analytical chemistry, y and x might represent the spectrum and associated set of constituent concentrations of a multicomponent sample which are related through Beer`s law. The model parameters are estimated during a calibration process in which both x and y are available for a number of observations (samples/specimens) which are collectively referred to as the calibration set. For new observations, the fitted calibration model is then used as the basis for predicting the unknown values of the new x`s (concentrations) form the associated new y`s (spectra) in the prediction set. This prediction procedure can be viewed as parameter estimation in an errors-in-variables (EIV) framework. In addition to providing a basis for simultaneous inference about the new x`s, consideration of the EIV framework yields a number of insights relating to the design and execution of calibration studies. A particularly interesting result is that predictions of the new x`s for individual samples can be improved by using seemingly unrelated information contained in the y`s from the other members of the prediction set. Furthermore, motivated by this EIV analysis, this result can be extended beyond the causal modeling context to a broader range of applications of multivariate calibration which involve the use of principal components regression.

We have developed a two-dimensional Shack-Hartman wavefront sensor that uses binary optic lenslet arrays to directly measure the wavefront slope (phase gradient) and amplitude of the laser beam. This sensor uses an array of lenslets that dissects the beam into a number of samples. The focal spot location of each of these lenslets (measured by a CCD camera) is related to the incoming wavefront slope over the lenslet. By integrating these measurements over the laser aperture, the wavefront or phase distribution can be determined. Since the power focused by each lenslet is also easily determined, this allows a complete measurement of the intensity and phase distribution of the laser beam. Furthermore, all the information is obtained in a single measurement. Knowing the complete scalar field of the beam allows the detailed prediction of the actual beam`s characteristics along its propagation path. In particular, the space- beamwidth product M{sup 2}, can be obtained in a single measurement. The intensity and phase information can be used in concert with information about other elements in the optical train to predict the beam size, shape, phase and other characteristics anywhere in the optical train. We present preliminary measurements of an Ar{sup +} laser beam and associated M{sup 2} calculations.

The quest for fabricating complex metal parts rapidly and with minimal cost has brought rapid prototyping (RP) processes to the forefront of the investment casting industry. Relatively recent advances in DTM Corporation`s selective laser sintering (SLS) and 3D Systems stereolithography (SL) processes have had a significant impact on the overall quality of patterns produced using these rapid prototyping processes. Sandia National Laboratories uses patterns generated from rapid prototyping processes to reduce the cycle time and cost of fabricating prototype and small lot production parts in support of a program called FASTCAST. The SLS process is used to fabricate patterns from materials such as investment casting wax, polycarbonate, and a new material called TrueForm PM{trademark}. With the timely introduction of each of these materials, the quality of patterns fabricated has improved. The development and implementation of SL QuickCast{trademark} software has enabled this process to produce highly accurate patterns for use in investment casting. This paper focuses on the successes with these new pattern materials and the infrastructure required to cast rapid prototyping patterns successfully. In addition, a brief overview of other applications of rapid prototyping at Sandia will be discussed.

Resistance degradation in PZT thin-film capacitors has been studied as a function of applied voltage, temperature, and film composition. It is found that the mean-time-to-failure (life-time or t{sub f}) of the capacitors shows a power law dependence on applied voltage of he form t{sub f} {proportional_to} V{sup {minus}n} (n {approximately} 4--5). The capacitor life-time also exhibits a temperature dependence of the form t{sub f} {proportional_to} exp(E{sub a}/kT), with an activation energy of {approximately} 0.8 eV. The steady-state leakage current in these samples appears to be bulk controlled. The voltage, temperature, and polarity dependence of the leakage current collectively suggest a leakage current mechanism most similar to a Frenkel-Poole process. The life-time and leakage current of the Nb-doped PZT films are superior to the undoped PZT films. This result can be explained based on the point-defect chemistry of the PZT system. Finally, the results indicate that the Nb-doped PZT films meet the essential requirements for decoupling capacitor applications.

First-principles density functional calculations and corresponding experimental results underline the importance of basic chemical concepts, such as coordination, valence saturation and promotion-hybridization energetics, in understanding bonding and diffusion of atoms at and on metal surfaces. Several examples are reviewed, including outer-layer relaxations of clean hcp(0001) surfaces, liquid-metal-embrittlement energetics, separation energies of metal-adatom dimers, concerted substitutional self-diffusion on fcc(001) surfaces, and adsorption and diffusion barrier sites for adatoms near steps.

The Department of Defense (DoD) operates hundreds of test, evaluation, and training facilities across the US and abroad. Due to the nature of their missions, these facilities are often remote and isolated from the utility grid. The preferred choice for power at these facilities has historically been manned diesel generators. The DoD Photovoltaic Review Committee, estimates that on the order of 350 million gallons of diesel fuel is burned each year to generate the 2000 GWh of electricity required to operate these remote military facilities. Other federal agencies, including the National Park Service and the USDA Forest Service use diesel generators for remote power needs as well. The generation of power diesel generators is both expensive and detrimental to the environment. The augmentation of power from diesel generators with power processing and battery energy storage enhances the efficiency and utilization of the generator resulting in lower fuel consumption and lower generator run- time in proportion to the amount of renewables added. The hybrid technology can both reduce the cost of power and reduce environmental degradation at remote DoD facilities. This paper describes the expected performance and economics of photovoltaic/diesel hybrid systems. Capabilities and status of systems now being installed at DoD facilities are presented along with financing mechanisms available within DoD.

Sandia National Laboratories developed a process to identify and remove the hazardous sub-components from dismantled weapons components utilizing real-time radiography and abrasive water-jet cutting. The components were then crushed, granulated, screened, and separated into an aluminium and a precious-and-base-metals fraction using air-tables. Plastics were further cleaned for disposal as non- hazardous waste.

Solid free form fabrication is one of the fastest growing automated manufacturing technologies that has significantly impacted the length of time between initial concept and actual part fabrication. Starting with CAD renditions of new components, several techniques such as stereolithography and selective laser sintering are being used to fabricate highly accurate complex three-dimensional concept models using polymeric materials. Coupled with investment casting techniques, sacrificial polymeric objects are used to minimize costs and time to fabricate tooling used to make complex metal castings. This paper will describe recent developments in a new technology, known as LENS{sup {trademark}} (Laser Engineered Net Shaping), to fabricate metal components directly from CAD solid models and thus further reduce the lead times for metal part fabrication. In a manner analogous to stereolithography or selective sintering, the LENS{sup {trademark}} process builds metal parts line by line and layer by layer. Metal particles are injected into a laser beam, where they are melted and deposited onto a substrate as a miniature weld pool. The trace of the laser beam on the substrate is driven by the definition of CAD models until the desired net-shaped densified metal component is produced.

The international scientific community has long had an interest in determining methods by which information regarding nuclear waste repositories, and the inherent danger to humanity, could be passed from generation to generation and society to society. Because nuclear waste will remain radioactive for thousands of years future generations must be warned of the dangers thus eliminating intentional or inadvertent intrusion. Member States of the IAEA have determined that the principle safety of such sites must not rely solely on long term institutional arrangements for the retention of information. It is believed that repository siting, design, operation and postoperation information should be gathered, managed and retained so that this information remains accessible to future societies over a very long period of time. The radionuclide life is 10,000 years; thus the retention of information continues beyond current societies, cultures and languages, and must be continually migrated to new retrieval technologies to assure access.

A great deal has been written about the history of science in America since World War II. Much of that work has explored the government`s research and development establishment, focusing on the scientific community immediately after the war. It is generally argued that the apparent triumphs of the huge and expensive wartime research and development projects gave rise to a belief that scientific resources should be nurtured and kept on hand - ready to provide service in an emergency. The Cold War drive for more and better weapons further fed this belief, leading to a massive system of national laboratories, military laboratories, and defense industries. The science of this complex is built on extensive financial support, the central strategy of which is that by steadily, and occasionally even lavishly funding large research programs, you will have a constant stream of scientific ideas that can be applied to national security purposes. What is true of science, is also true, in slightly modified form, of postwar engineering. The story I want to tell you today is, I think, an example of the way Cold War engineering r&d for national security worked. This report describes aspects of the Sandia National Laboratories.

A strategic surety roadmap for high consequence software systems under the High Integrity Software (HIS) Program at Sandia National Laboratories guides research in identifying methodologies to improve software surety. Selected research tracks within this roadmap are identified and described detailing current technology and outlining advancements to be pursued over the coming decade to reach HIS goals. The tracks discussed herein focus on Correctness by Design, and System Immunology{trademark}. Specific projects are discussed with greater detail given on projects involving Correct Specification via Visualization, Synthesis, & Analysis; Visualization of Abstract Objects; and Correct Implementation of Components.

Computational modeling has been performed to determine optimum operational parameters for a piston-driven molten solder jetting device used to create array interconnects for BGA applications. The device is capable of delivering a 20 x 20 array of 600-800 {mu}m diameter molten 60Sn40Pb solder droplets onto an array of copper pads and primarily consists of an electromechanically driven piston, a heated reservoir, and an orifice plate. computer simulations were performed to determine the relationship between the amplitude and the rate of piston displacement, the onset of fluid ``pinch off``, and the production of satellite droplets. Results show that stable droplets are generated when the volume of the displaced fluid has a spherical diameter that is approximately equal to the orifice diameter.

This document, after giving a summary of Sandia`s mission, describes technology transfer efforts and accomplishments at Sandia. This includes information on their user facilities: the combustion research facility, the national solar thermal test facility, and the electronics quality and reliability center.

NASA-Ames Research Center, in collaboration with Sandia National Laboratories, is developing a Scannerless Terrain Mapper (STM) for autonomous vehicle guidance through the use of virtual reality. The STM sensor is based on an innovative imaging optical radar technology that is being developed by Sandia National Laboratories. The sensor uses active flood-light scene illumination and an image intensified CCD camera receiver to rapidly produce and record very high quality range imagery of observed scenes. The STM is an all solid-state device (containing no moving parts) and offers significant size, performance, reliability, simplicity, and affordability advantages over other types of 3-D sensor technologies, such as scanned laser radar, stereo vision, and structured lighting. The sensor is based on low cost, commercially available hardware, and is very well suited for affordable application to a wide variety of military and commercial uses, including: munition guidance, target recognition, robotic vision, automated inspection, driver enhanced vision, collision avoidance, site security and monitoring, and facility surveying. This paper reviews the sensor technology, discusses NASA`s terrain mapping applications, and presents results from the initial testing of the sensor at NASA`s planetary landscape simulator.

SrCo{sub 0.5}FeO{sub x} (SCF) is an attractive material for oxygen separation membranes and for use in catalytic membrane reactors. While tubes of this material have been prepared by extrusion, further improvements in oxygen transport performance may be gained by preparing thinner membranes on porous supports. In this paper, we will discuss the deposition of thick films by spray deposition and centrifugal casting, and thin films by pyrolysis of chemical precursors. For the chemically derived thin films, porous MgO supports were used as membrane supports. Three types of precursor solutions were employed for dipcoating: a Pechini type solution, a nitrate-based solution, and a citrate-based solution. To prevent the infiltration of the precursor into the support, the support was backfilled with a material that decomposed at higher temperatures than the precursors. Cracking due to the volume changes during drying and pyrolysis of the precursors is discussed. Thick films were prepared by spray coating and centrifugal casting. Spray deposition of thick film membranes was accomplished by air brushing SCF from a water-based suspension onto the surface of a porous MgO support. Films on the interior surface of the supports were prepared by centrifugal casting using a xylene/butanol-based SCF suspension. Unlike extruded tubes, thick films undergo constrained sintering due to the presence of the support, which greatly reduces the densification rate. For membranes prepared by both approaches, we will discuss the effects of heating schedules on membrane microstructure, densification behavior, and cracking.

Plasma-induced-damage often degrades the electrical and optical properties of compound semiconductor devices. Despite the fact that the binding energy of GaN is larger than that for more conventional III--V compounds, etch damage is still a concern. Photoluminescence measurements and atomic force microscopy have been used to determine the damage induced in GaN by exposure to both electron cyclotron resonance (ECR) and inductively coupled plasmas (ICP) generated Ar plasmas.

This paper presents a portion of the work on specification, design, and implementation of safety-critical systems such as reactor control systems. A natural approach to this problem, once all the requirements are captured, would be to state the requirements formally and then either to prove (preferably via automated tools) that the system conforms to spec (program verification), or to try to simultaneously generate the system and a mathematical proof that the requirements are being met (program derivation). An obstacle to this is frequent presence of partially defined operations within the software and its specifications. Indeed, the usual proofs via first order logic presuppose everywhere defined operations. Recognizing this problem, David Gries, in ``The Science of Programming,`` 1981, introduced the concept of partial functions into the mainstream of program correctness and gave hints how his treatment of partial functions could be formalized. Still, however, existing theorem provers and software verifiers have difficulties in checking software with partial functions, because of absence of uniform first order treatment of partial functions within classical 2-valued logic. Several rigorous mechanisms that took partiality into account were introduced [Wirsing 1990, Breu 1991, VDM 1986, 1990, etc.]. However, they either did not discuss correctness proofs or departed from first order logic. To fill this gap, the authors provide a semantics for software correctness proofs with partial functions within classical 2-valued 1st order logic. They formalize the Gries treatment of partial functions and also cover computations of functions whose argument lists may be only partially available. An example is nuclear reactor control relying on sensors which may fail to deliver sense data. This approach is sufficiently general to cover correctness proofs in various implementation languages.

The US Department of Energy (DOE) uses sensitive or classified parts and material that must be protected and accounted for. The authors believe there is a need for an automated system that can help protect and monitor these parts and material. In response to this need Sandia National Laboratories (SNL) has developed a real-time personnel and material tracking system called PAMTRAK that has been installed at selected DOE facilities. PAMTRAK safeguards sensitive parts and material by tracking tags worn by personnel and by monitoring sensors attached to the parts or material. This paper describes the goals when designing PAMTRAK, the PAMTRAK system components, the current installations, and the benefits a site can expect when using PAMTRAK.

Planar, surface micromachined pressure sensors have been fabricated by an extension of the chemical-mechanical polishing (CMP) process. CMP eliminates many of the fabrication problems associated with the photolithography, dry etch, and metallization of non-planar devices. Furthermore, CMP adds additional design flexibility. The sensors are based upon deformable, silicon nitride diaphragms with polysilicon piezoresistors. Absolute pressure is detected by virtue of reference pressure cavities underneath the diaphragms. Process details are discussed and characteristics from many devices are presented.

Phosphorus diffusions are used in the fabrication process for nearly all crystalline-silicon (c-Si) photovoltaic solar cells to form the emitter of the solar cell. These phosphorous diffusions are also well known to have beneficial gettering benefits, i.e., deleterious metallic impurities are gettered from the bulk of the c-Si substrate into the phosphorous doped layer. In this study, we examined the effect of oxidations performed after the phosphorus diffusion. We were particularly interested in using the oxidation to passivate the surface of the phosphorus diffusion. Post-diffusion oxidations or moderate temperature steps in oxidizing ambients are also commonly found in commercial fabrication sequences of c-Si solar cells. we found that the bulk lifetime was degraded in Czochralski (Cz) silicon due to the post-diffusion oxidation unless there was a gettering agent present during the oxidation. Possible explanations for these results are presented at the end of the paper.

The dehydrogenation of propane and isobutane was studied in hydrogen permselective packed bed membrane reactors and conventional packed bed reactors. Two different types of developmental membranes were investigated: sol-gel derived silica-based membranes and a pure palladium thin film supported by a porous ceramic substrate. The palladium membranes deactivated and eventually failed when exposed to both isobutane and propane dehydrogenation temperatures above 773 K. Moderate improvements in propylene and isobutylene yields were obtained with the silica-based membrane reactors. An isobutylene yield of 48 mole percent was obtained at a liquid hourly space velocity (LHSV) of 1.8 and temperature of 798 K compared to a yield of 39 percent in a conventional reactor operated with the same flow rate. Similar improvements in propylene yield were obtained when the silica-based membranes were tested in propane dehydrogenation experiments. There was no significant difference in the reaction selectivities for the desired olefin products when the membrane and conventional reactors were operated with the scone LHSV However, for a constant value of the olefin yield, the membrane reactors had a higher reaction selectivity since the desired yield was achieved at a higher LHSV where there was less time for side products to form. Catalyst deactivation rates were generally greater in the membrane reactors, especially when the reactors were operated with high hydrogen removal rates at temperatures of 773 K and above.

GaAs Junction Field Effect Transistors (JFETs) have attracted renewed attention for low-power, low-voltage electronics. JFETs have a significant advantage over MESFETs for low-power operation due to their higher gate barrier to current flow resulting from p/n junction gate. This paper reports recent advances in an all ion implanted self-aligned GaAs JFET with a gate length down to 0.3 {mu}m. By employing shallopw SiF implants next to the gate, dielectric sidewall spacers, and 50 keV source and drain implants, JFETs with a f{sub t} up to 49 GHz with good pinchoff and subthreshold characteristics have been realized. In addition, the JFET benefits from the use of shallow Zn or Cd implantation to form abrupt p{sup +}/n gate profiles.

Deep etching of GaAs is a critical process step required for many device applications including fabrication of through-substrate via holes for monolithic microwave integrated circuits (MMICs). Use of high-density plasmas, including inductively coupled plasmas (ICP), offers an alternative approach to etching vias as compared to more conventional parallel plate reactive ion etch systems. This paper reports ICP etching of GaAs vias at etch rates of about 5.3 {mu}m/min with via profiles ranging from highly anistropic to conical.

In this study, 33 different conversion coatings were applied to 5 different Al alloy substrates. Salt spray exposure testing and EIS (electrochemical impedance spectroscopy) were conducted for comparison. A relation was developed.

With the demonstration of implant doping of GaN and the resulting need to perform the activation anneal at 1100 C, details of thermal stability of the GaN surface needs to be understood. This work reports on the use of a sputtered AlN encapsulant to preserve the surface of GaN during such annealing. The surface was characterized by formation of Pt/Au Schottky contacts and by AES. Schottky contacts deposited an GaN annealed wtih the AlN encapsulant displayed good rectification properties while those formed on GaN annealed uncapped approached ohmic behavior. AES analysis supports the hypothesis that the uncapped sample has lost N from the very near surface which creates N-vacancies that act as donors and thereby form an n{sup +}-surface layer.

This paper presents design, analysis, and first results of the high brightness electron beam experiments currently under investigation at Sandia. Anticipated beam parameters are: energy 12 MeV, current 35-40 kA, rms radius 0.5 mm, pulse duration 40 ns FWHM. The accelerator is SABRE, a pulsed LIVA modified to higher impedance, and the electron source is a magnetically immersed foilless electron diode. 20 to 30 Tesla solenoidal magnets are required to insulate the diode and contain the beam to its extremely small sized (1 mm) envelope. These experiments are designed to push the technology to produce the highest possible electron current in a submillimeter radius beam. Design, numercial simulations, and first experimental results are presented.

Development of a complementary heterostructure field effect transistor (CHFET) technology for low-power, mixed-mode digital-microwave applications is presented. Digital CHFET technology with independently optimizable transistors has been shown to operate with 319 ps loaded gate delays at 8.9 fJ. Power consumption is dominated by leakage currents of the p-channel FET, while performance is determined by the characteristics of 0.7 {mu}m gate length devices. As a microwave technology, the nJFET forms the basis of low-power cirucitry without any modification to the digital process. Narrow band amplification with a 0.7x100 {mu}m nJFET has been demonstrated at 2.1-2.4 GHz with gains of 8-10 dB at 1 mW power. These amplifiers showed a minimum noise figure of 2.5 dB. Next generation CHFET transistors with sub 0.5 {mu}m gate lengths have also been developed. Cutoff frequencies of 49 and 11.5 GHz were achieved for n- and p-channel FETs with 0.3 and 0.4 {mu}m gates, respectively. These FETs will enable enhancements in both digital and microwave circuits.

Extracting information from unstructured text has become an important research area in recent years due to the large amount of text now electronically available. This status report describes the findings and work done during the second year of a two-year Laboratory Directed Research and Development Project. Building on the first-year`s work of identifying important entities, this report details techniques used to group words into semantic categories and to output templates containing selective document content. Using word profiles and category clustering derived during a training run, the time-consuming knowledge-building task can be avoided. Though the output still lacks in completeness when compared to systems with domain-specific knowledge bases, the results do look promising. The two approaches are compatible and could complement each other within the same system. Domain-independent approaches retain appeal as a system that adapts and learns will soon outpace a system with any amount of a priori knowledge.

This paper provides an overview of the history and process of establishing a cooperative research and development agreement (CRADA) between Sandia National Laboratories and Magnavox Electronic Systems Company for the design, development, and testing of a 360-degree scanning, imaging, intrusion detection sensor. The subject of the CRADA is the Advanced Exterior Sensor (AES). It is intended for exterior use at ranges from 50 to 1,500 meters and uses a combination of three sensing technologies (infrared, visible, and radar) and a new data processing method to provide low false-alarm intrusion detection and tracking combined with immediate visual assessment. The establishment of this CRADA represents a new paradigm in the cooperation between the Department of Defense, the Department of Energy, the National Laboratories and Private Industry. Although a formal document has now been executed, a CRADA is, nonetheless, primarily an agreement to work with each other to achieve goals that might otherwise be unattainable.

In this paper, the authors explore the feasibility of using the distributed Bragg reflector, grown on the substrate for a VCSEL (Vertical Cavity Surface Emitting Laser), to provide waveguiding within the substrate. This waveguiding could serve as an interconnection among VCSELs in an array. Before determining the feasibility of waveguide interconnected VCSELs, two analysis methods are presented and evaluated for their applicability to this problem. The implementations in Mathematica of both these methods are included. Results of the analysis show that waveguiding in VCSEL structures is feasible. Some of the many possible uses of waveguide interconnected VCSELs are also briefly discussed. The tools and analysis presented in this report can be used to evaluate such system concepts and to do detailed design calculations.

This is the final report of a one-year, Laboratory-Directed Research and Development (LDRD) project at the Los Alamos National Laboratory (LANL). If a beam-chopping system could be developed for the Los Alamos Meson Physics Facility low-energy beam line, there would be potential to operate the Los Alamos Neutron Scattering Center (LANSCE) at much higher power and duty factor and enable such operation with a radio-frequency quadrapole (RFQ) injector. This would greatly extend the capability of the facility. To accommodate LANSCE operation in the new configuration, a chopped beam must be created in the low-energy transport line before the RFQ. Chopping in this region has never been demonstrated and constitutes the major uncertainty of the proposal and determines the critical path for project completion. This study produces a better understanding of the physics involved in chopping an H-beam in a dilute plasma background, and in transporting a chopped H-beam through a neutralized or partially neutralized plasma channel, as well as an estimate for the optimum neutralization strategy for the beam chopping and transport between the ion source and the RFQ.

This 1995 report contains data from routine radiological and non-radiological environmental monitoring activities. Summaries of significant environmental compliance programs in progress, such as National Environmental Policy Act documentation, environmental permits, environmental restoration and various waste management programs at Sandia National Laboratories in Albuquerque, New Mexico, are included.

DOE installations possessing sufficient quantities of fissile material to potentially constitute a critical mass, such that the excessive exposure of personnel to radiation from a nuclear accident is possible, are required to provide nuclear accident dosimetry services. This document describes the personal nuclear accident dosimeter (PNAD) used by SNL and prescribes methodologies to initially screen, and to process PNAD results. In addition, this report describes PNAD dosimetry results obtained during the Nuclear Accident Dosimeter Intercomparison Study (NAD23), held during 12-16 June 1995, at Los Alamos National Laboratories. Biases for reported neutron doses ranged from -6% to +36% with an average bias of +12%.

Ten commercial MgO powders were evaluated for their suitability to act as a binder in the separator of thermal batteries to immobilize the electrolyte when it is molten. One brand in particular, Maglite S from Calgon, outperformed all the others. This report describes the results of a characterization study of this MgO as well as similar materials from other commercial vendors. The study objective was to define the critical properties of Maglite S MgO that are responsible for its superior performance in thermal-battery separators. Separator mixes were prepared with the various MgO powders and the resulting powders and pellets were characterized, to correlate key physical properties of these materials to select physical and chemical properties of the MgO powders used in their preparation. The MgO pore-size distribution was the only parameter that could be related to the deformation and electrolyte-leakage behavior of separator pellets. A potential replacement for the Maglite S is currently being qualified, since Maglite S MgO is no longer available.

This report summarizes the environmental surveillance activities conducted by Sandia National Laboratories. Sandia National Laboratories` responsibility for environmental surveillance results extends to those activities performed by Sandia National Laboratories or under its direction. Results from other organizations environmental surveillance activities are included to provide a measure of completeness. Other environmental compliance programs such as the National Environmental Policy Act of 1969, environmental permits, and environmental restoration and waste management programs are also included in this report, prepared for the U.S. Department of Energy (DOE) in compliance with DOE Order 5400.1.

Capillary barriers consisting of tilted fine-over-coarse layers have been suggested as landfill covers as a means to divert water infiltration away from sensitive underground regions under unsaturated flow conditions, especially for arid and semi-arid regions. Typically, the HELP code is used to evaluate landfill cover performance and design. Unfortunately, due to its simplified treatment of unsaturated flow and its essentially one-dimensional nature, HELP is not adequate to treat the complex multidimensional unsaturated flow processes occurring in a tilted capillary barrier. In order to develop the necessary mechanistic code for the performance evaluation of tilted capillary barriers, an efficient and comprehensive unsaturated flow code needs to be selected for further use and modification. The present study evaluates a number of candidate mechanistic unsaturated flow codes for application to tilted capillary barriers. Factors considered included unsaturated flow modeling, inclusion of evapotranspiration, nodalization flexibility, ease of modification, and numerical efficiency. A number of unsaturated flow codes are available for use with different features and assumptions. The codes chosen for this evaluation are TOUGH2, FEHM, and SWMS{_}2D. All three codes chosen for this evaluation successfully simulated the capillary barrier problem chosen for the code comparison, although FEHM used a reduced grid. The numerical results are a strong function of the numerical weighting scheme. For the same weighting scheme, similar results were obtained from the various codes. Based on the CPU time of the various codes and the code capabilities, the TOUGH2 code has been selected as the appropriate code for tilted capillary barrier performance evaluation, possibly in conjunction with the infiltration, runoff, and evapotranspiration models of HELP. 44 refs.

An oblique penetration modeling procedure is evaluated by correlation with onboard acceleration data from a series of six penetration tests into Antelope Dry Lake soil at Tonopah Test Range, Nevada. The modeling represents both the loading which is coupled to the penetrator bending and the penetrator structure including connections between the major subsections. Model results show reasonable agreement with the data which validates the modeling procedure within a modest uncertainty related to accelerometer clipping and rattling of the telemetry package. The experimental and analytical results provide design guidance for the location and lateral restraint of components to reduce their shock environment.

CHEM{_}MACCS has been developed from the radiological accident consequence code, MACCS, to perform probabilistic calculations of potential off-site consequences of the accidental atmospheric release of hazardous chemicals. The principal phenomena considered in CHEM{_}MACCS are atmospheric transport, mitigative actions based on dose projection, dose accumulation by a number of pathways, and early and latent health effects. CHEM{_}MACCS provides the following capabilities: (1) statistical weather sampling data (8,760 hourly data points per year), (2) population dose and health effect risk calculations based on site-specific population data, (3) health effects calculations including the consideration of potential site specific mitigative actions (evacuation and shielding), and (4) modeling of multiple release segments. Three different sample problems are contained in this report to show how to use CHEM{_}MACCS. Three test problems are run to compare CHEM{_}MACCS and D2PC. The doses versus the downwind centerline distances from the source for the given doses are in very close agreement.

An autonomous gas chromatograph system was designed and built to support the Thermal Enhanced Vapor Extraction System (TEVES) demonstration. TEVES is a remediation demonstration that seeks to enhance an existing technology (vacuum extraction) by adding a new technology (soil heating). A pilot scale unit was set up at one of the organic waste disposal pits at the Sandia National Laboratories Chemical Waste Landfill (CWL) in Tech Area 3. The responsibility for engineering a major part of the process instrumentation for TEVES belonged to the Manufacturing Control Subsystems Department. The primary mission of the one-of-a-kind hardware/software system is to perform on-site gas sampling and analysis to quantify a variety of volatile organic compounds (VOCs) from various sources during TEVES operations. The secondary mission is to monitor a variety of TEVES process physical parameters such as extraction manifold temperature, pressure, humidity, and flow rate, and various subsurface pressures. The system began operation in September 1994 and was still in use on follow-on projects when this report was published.

In support of the Motorola CRADA, the capabilities of the computational fluid dynamics code FIDAP (Fluid Dynamics International) for simulating problems involving fluid flow, heat transport, and chemical reactions have been assessed and enhanced as needed for semiconductor-processing applications (e.g. chemical vapor deposition). A novel method of treating surface chemical species that uses only pre-existing FIDAP commands is described and illustrated with test problems. A full-Jacobian treatment of the chemical reaction rate expressions during formation of the stiffness matrix has been implemented in FIDAP for both the Arrhenius-parameter and user-subroutine methods of specifying chemical reactions, where the Jacobian terms can be calculated analytically or numerically. This formulation is needed to obtain convergence when reaction rates become large compared to transport rates (stiff chemistry). Several test problems are analyzed, and in all cases this approach yields good convergence behavior, even for extremely stiff fluid-phase and surface reactions. A stiff segregated algorithm has been developed and implemented in FIDAP. Analysis of test problems indicates that this algorithm yields improved convergence behavior compared with the original segregated algorithm. This improved behavior enables segregated techniques to be applied to problems with stiff chemistry, as required for large three-dimensional multi-species problems.

The current that flows between the electrical test equipment and the nuclear explosive must be limited to safe levels during electrical tests conducted on nuclear explosives at the DOE Pantex facility. The safest way to limit the current is to use batteries that can provide only acceptably low current into a short circuit; unfortunately this is not always possible. When it is not possible, current limiters, along with other design features, are used to limit the current. Three types of current limiters, the fuse blower, the resistor limiter, and the MOSFET-pass-transistor limiters, are used extensively in Pantex test equipment. Detailed failure mode and effects analyses were conducted on these limiters. Two other types of limiters were also analyzed. It was found that there is no best type of limiter that should be used in all applications. The fuse blower has advantages when many circuits must be monitored, a low insertion voltage drop is important, and size and weight must be kept low. However, this limiter has many failure modes that can lead to the loss of over current protection. The resistor limiter is simple and inexpensive, but is normally usable only on circuits for which the nominal current is less than a few tens of milliamperes. The MOSFET limiter can be used on high current circuits, but it has a number of single point failure modes that can lead to a loss of protective action. Because bad component placement or poor wire routing can defeat any limiter, placement and routing must be designed carefully and documented thoroughly.

Transient dynamics simulations are commonly used to model phenomena such as car crashes, underwater explosions, and the response of shipping containers to high-speed impacts. Physical objects in such a simulation are typically represented by Lagrangian meshes because the meshes can move and deform with the objects as they undergo stress. Fluids (gasoline, water) or fluid-like materials (earth) in the simulation can be modeled using the techniques of smoothed particle hydrodynamics. Implementing a hybrid mesh/particle model on a massively parallel computer poses several difficult challenges. One challenge is to simultaneously parallelize and load-balance both the mesh and particle portions of the computation. A second challenge is to efficiently detect the contacts that occur within the deforming mesh and between mesh elements and particles as the simulation proceeds. These contacts impart forces to the mesh elements and particles which must be computed at each timestep to accurately capture the physics of interest. In this paper we describe new parallel algorithms for smoothed particle hydrodynamics and contact detection which turn out to have several key features in common. Additionally, we describe how to join the new algorithms with traditional parallel finite element techniques to create an integrated particle/mesh transient dynamics simulation. Our approach to this problem differs from previous work in that we use three different parallel decompositions, a static one for the finite element analysis and dynamic ones for particles and for contact detection. We have implemented our ideas in a parallel version of the transient dynamics code PRONTO-3D and present results for the code running on a large Intel Paragon.

Sandia National Laboratories and Oceania, Inc. entered into a Cooperative Research and Development Agreement (CRADA) in November 1993 to provide ``Information Integrity and Privacy for Computerized Medical Patient Records`` (CRADA No. SC93/01183). The main objective of the project was to develop information protection methods that are appropriate for databases of patient records in health information systems. This document describes the findings and alternative solutions that resulted from this CRADA.

PHASER (Probabilistic Hybrid Analytical System Evaluation Routine) is a software tool that has the capability of incorporating subjective expert judgment into probabilistic safety analysis (PSA) along with conventional data inputs. An earlier report described the PHASER methodology, but only gave a cursory explanation about how dependence was incorporated in Version 1.10 and about how ``Importance`` and ``Sensitivity`` measures were to be incorporated in Version 2.00. A more detailed description is given in this report. The basic concepts involve scale factors and confidence factors that are associated with the stochastic variability and subjective uncertainty (which are common adjuncts used in PSA), and the safety risk extremes that are crucial to safety assessment. These are all utilized to illustrate methodology for incorporating dependence among analysis variables in generating PSA results, and for Importance and Sensitivity measures associated with the results that help point out where any major sources of safety concern arise and where any major sources of uncertainty reside, respectively.

This work addresses a new kind of silicon based chemical sensor that combines the reliability and stability of silicon microelectronic field effect devices with the highly selective and sensitive immunoassay. The sensor works on the principle that thin SiN layers on lightly doped Si can detect pH changes rapidly and reversibly. The pH changes affect the surface potential, and that can be quickly determined by pulsed photovoltage measurements. To detect other species, chemically sensitive films were deposited on the SiN where the presence of the chosen analyte results in pH changes through chemical reactions. A invention of a cell sorting device based on these principles is also described. A new method of immobilizing enzymes using Sandia`s sol-gel glasses is documented and biosensors based on the silicon wafer and an amperometric technique are detailed.

Microsensors do not have the selectivity to chemical species available in large laboratory instruments. This project employed arrays of catalytically gated silicon microsensors with different catalysts to create data streams which can be analyzed by pattern recognition programs. One of the most significant accomplishments of the program was the demonstration of that mixtures of H{sub 2} with the oxidants NO{sub x} and O{sub 2} could distinguished from one another by the use of different catalytic metals on the Sandia Robust Hydrogen (SRH) sensors and the newly developed pattern recognition algorithm. This sensor system could be used to identify explosive gas mixtures and analyze exhaust streams for pollution control.

This manual describes the use of MPSalsa, an unstructured finite element (FE) code for solving chemically reacting flow problems on massively parallel computers. MPSalsa has been written to enable the rigorous modeling of the complex geometry and physics found in engineering systems that exhibit coupled fluid flow, heat transfer, mass transfer, and detailed reactions. In addition, considerable effort has been made to ensure that the code makes efficient use of the computational resources of massively parallel (MP), distributed memory architectures in a way that is nearly transparent to the user. The result is the ability to simultaneously model both three-dimensional geometries and flow as well as detailed reaction chemistry in a timely manner on MT computers, an ability we believe to be unique. MPSalsa has been designed to allow the experienced researcher considerable flexibility in modeling a system. Any combination of the momentum equations, energy balance, and an arbitrary number of species mass balances can be solved. The physical and transport properties can be specified as constants, as functions, or taken from the Chemkin library and associated database. Any of the standard set of boundary conditions and source terms can be adapted by writing user functions, for which templates and examples exist.

The USW SD-7 drill hole is one of several holes drilled under Site Characterization Plan Study 8.3.1.4.3.1, also known as the Systematic Drilling Program, as part of the U.S. Department of Energy characterization program at Yucca Mountain, Nevada. The Yucca Mountain site has been proposed as the potential location of a repository for high-level nuclear waste. The SD-7 drill hole is located near the southern end of the potential repository area and immediately to the west of the Main Test Level drift of the Exploratory Studies Facility. The hole is not far from the junction of the Main Test Level drift and the proposed South Ramp decline. Drill hole USW SD-7 is 2675.1 ft (815.3 m) deep, and the core recovered nearly complete sections of ash-flow tuffs belonging to the lower half of the Tiva Canyon Tuff, the Pah Canyon Tuff, and the Topopah Spring Tuff, all of which are part of the Miocene Paintbrush Group. Core was recovered from much of the underlying Calico Hills Formation, and core was virtually continuous in the Prow Pass Tuff and the Bullfrog Tuff. The SD-7 drill hole penetrated the top several tens of feet into the Tram Tuff, which underlies the Prow Pass and Bullfrog Tuffs. These latter three units are all formations of the Crater Flat Group, The drill hole was collared in welded materials assigned to the crystal-poor middle nonlithophysal zone of the Tiva Canyon Tuff; approximately 280 ft (85 m) of this ash-flow sheet was penetrated by the hole. The Yucca Mountain Tuff appears to be missing from the section at the USW SD-7 location, and the Pah Canyon Tuff is only 14.5 ft thick. The Pah Canyon Tuff was not recovered in core because of drilling difficulties, suggesting that the unit is entirely nonwelded. The presence of this unit is inferred through interpretation of down-hole geophysical logs.

This LDRD program No. 3505.230 explored a new approach to monolithic integration of active waveguides and rare-earth solid state lasers directly onto III-V substrates. It involved selectively incorporating rare-earth ions into spin-on glasses (SOGs) that could be solvent cast and then patterned with conventional microelectronic processing. The patterned, rare-earth spin-on glasses (RESOGs) were to be photopumped by laser diodes prefabricated on the wafer and would serve as directly integrated active waveguides and/or rare-earth solid state lasers.

Under the auspices of the {open_quotes}Government/Industry Wind Technology Applications Project{close_quotes} [{open_quotes}Letter of Interest{close_quotes} (LOI) Number RC-1-11101], Flo Wind Corp. has successfully developed, tested, and delivered a high-energy rotor upgrade candidate for their 19-meter Vertical Axis Wind Turbine. The project included the demonstration of the innovative extended height-to-diameter ratio concept, the development of a continuous span single-piece composite blade, the demonstration of a continuous blade manufacturing technique, the utilization of the Sandia National Laboratories developed SNLA 2150 natural laminar flow airfoil and the reuse of existing wind turbine and wind power plant infrastructure.

PHASER (Probabilistic Hybrid Analytical System Evaluation Routine) is a computer code for solving the top event probability of a system fault tree. It has the capability for easy migration of individual basic event probabilities from a zero-{open_quotes}scale{close_quotes}-factor (completely subjective) state to one in which the analyst has total knowledge (completely stochastic) about each basic event. The code implements a fuzzy algebra solution for subjective data, a probabilistic solution for stochastic data, and a hybrid mathematics solution for data that are partly subjective and partly stochastic. Events that are not completely subjective or completely stochastic are hybrid events and are internally handled as such. The stochastic and fuzzy ranges of uncertainty in the top event probability are also computed for the analyst. These are provided in the form of a fuzzy function for the subjective uncertainty, a probability density function (PDF) for the stochastic variability, and the overall {open_quotes}confidence{close_quotes} factors for the two constituents of uncertainty, giving a complete hybrid result. PHASER interfaces with other Sandia codes (SABLE, LHS and LHSPOST) to assist the user in determining cutsets, and to compute probability density functions.

In 1983, high-level radioactive waste repository performance requirements related to groundwater travel time were defined by NRC subsystem regulation 10 CFR 60.113. Although DOE is not presently attempting to demonstrate compliance with that regulation, understanding of the prevalence of fast paths in the groundwater flow system remains a critical element of any safety analyses for a potential repository system at Yucca Mountain, Nevada. Therefore, this analysis was performed to allow comparison of fast-path flow against the criteria set forth in the regulation. Models developed to describe the conditions for initiation, propagation, and sustainability of rapid groundwater movement in both the unsaturated and saturated zones will form part of the technical basis for total- system analyses to assess site viability and site licensability. One of the most significant findings is that the fastest travel times in both unsaturated and saturated zones are in the southern portion of the potential repository, so it is recommended that site characterization studies concentrate on this area. Results support the assumptions regarding the importance of an appropriate conceptual model of groundwater flow and the incorporation of heterogeneous material properties into the analyses. Groundwater travel times are sensitive to variation/uncertainty in hydrologic parameters and in infiltration flux at upper boundary of the problem domain. Simulated travel times are also sensitive to poorly constrained parameters of the interaction between flow in fractures and in the matrix.

This report provides a users` guide for parallel processing ITS on a UNIX workstation network, a shared-memory multiprocessor or a massively-parallel processor. The parallelized version of ITS is based on a master/slave model with message passing. Parallel issues such as random number generation, load balancing, and communication software are briefly discussed. Timing results for example problems are presented for demonstration purposes.

The work is part of the rock mechanics effort for the Yucca Mountain Site Characterization Program. The laboratory-scale experiments are intended to provide high quality data on the mechanical behavior of jointed structures that can be used to validate complex numerical models for rock-mass behavior. Frictional sliding between simulated rock joints was studied using phase shifting moire interferometry. A model, constructed from stacks of machined and sandblasted granite plates, contained a central hole bore normal to the place so that frictional slip would be induced between the plates near the hole under compressive loading. Results show a clear evolution of slip with increasing load. Since the rock was not cycled through loading- unloading, the quantitative differences between the three data sets are probably due to a ``wearing-in`` effect. The highly variable spatial frequency of the data is probably due to the large grain size of the granite and the stochastic frictional processes. An unusual feature of the evolution of slip with increasing load is that as the load gets larger, some plates seem to return to a null position. Figs, 6 refs.

The Department of Energy is investigating Yucca Mountain, Nevada as a potential site for commercial radioactive waste disposal in a mined geologic repository. One critical aspect of site suitability is the tectonic stability of the repository site. The levels of risk from both actual fault displacements in the repository block and ground shaking from nearby earthquakes are being examined. In particular, it is necessary to determine the expected level of ground shaking at the repository depth for large seismic sources such as nearby large earthquakes or underground nuclear explosions (UNEs). Earthquakes are expected to cause the largest ground motions at the site, however, only underground nuclear explosion data have been obtained at the repository depth level (about 350m below the ground level) to date. In this study we investigate ground motion from Nevada Test Site underground nuclear explosions recorded at Yucca Mountain to establish a compressional velocity model for the uppermost 350m of the mountain. This model is useful for prediction of repository-level ground motions for potential large nearby earthquakes.

The Do-It-Now (DIN) building maintenance system is proposed to reduce the cost of routine building maintenance and repairs and to improve customer satisfaction with maintenance services. DIN uses a team approach to periodically inspect buildings and provide maintenance services on the spot. It emphasizes communications between the customers and the craftspeople performing the work. The system was designed using a reengineering approach that characterized the existing maintenance work control system, analyzed comparable systems in other DOE laboratories, envisioned an ideal system, and proposed a workable, testable system for initial implementation. At each stage, input was solicited from customer representatives and Facilities management to ensure meeting customer requirements with an implementable system.

This report describes the analysis and conclusion of an investigation of the carbon monoxide emissions resulting from Sandia National Laboratories and Department of Energy (DOE) commuter and on-base traffic for the Clean Air Act (CAA) Conformity Determination. Albuquerque/Bernalillo County was classified as a nonattainment area by the Environmental Protection Agency. Nonattainment area is an area which is shown by monitored data or which is calculated by air quality modeling to exceed any National Ambient Air Quality Standard (NAAQS) for the pollutant. Albuquerque/Bernalillo County exceeds the NAAQS for carbon monoxide and ozone. The Conformity Determination was needed to complete the CAA Title V Permitting process for SNL and the DOE. The analysis used the EPA approved MOBILE5a Carbon Monoxide (CO) emissions modeling program. This analysis will provide a baseline for mobile sources to allow Sandia to estimate any future activity and how that activity will impact CO emissions. The General Conformity Rule (AQCR 43) requires that operations which will increase CO emissions in nonattaimnent or maintenance areas such as Bernalillo County undergo conformity analyses to determine whether or not they will impact ambient air quality in the area.

The US DOE has amassed over 555,000 metric tons of depleted uranium from its uranium enrichment operations. Rather than dispose of this depleted uranium as waste, this study explores a beneficial use of depleted uranium as metal shielding in casks designed to contain canisters of vitrified high-level waste. Two high-level waste storage, transport, and disposal shielded cask systems are analyzed. The first system employs a shielded storage and disposal cask having a separate reusable transportation overpack. The second system employs a shielded combined storage, transport, and disposal cask. Conceptual cask designs that hold 1, 3, 4 and 7 high-level waste canisters are described for both systems. In all cases, cask design feasibility was established and analyses indicate that these casks meet applicable thermal, structural, shielding, and contact-handled requirements. Depleted uranium metal casting, fabrication, environmental, and radiation compatibility considerations are discussed and found to pose no serious implementation problems. About one-fourth of the depleted uranium inventory would be used to produce the casks required to store and dispose of the nearly 15,400 high-level waste canisters that would be produced. This study estimates the total-system cost for the preferred 7-canister storage and disposal configuration having a separate transportation overpack would be $6.3 billion. When credits are taken for depleted uranium disposal cost, a cost that would be avoided if depleted uranium were used as cask shielding material rather than disposed of as waste, total system net costs are between $3.8 billion and $5.5 billion.

An integral part of the licensing procedure for the potential nuclear waste repository at Yucca Mountain, Nevada, involves characterization of the in situ rheology for the design and construction of the facility and the emplacement of canisters containing radioactive waste. The data used to model the thermal and mechanical behavior of the repository and surrounding lithologies include dry and saturated bulk densities, average grain density, porosity, compressional and shear wave velocities, elastic moduli, and compressional and tensional fracture strengths. In this study, a suite of experiments was performed on cores recovered from boreholes UE25 NRG-2, 2A, 2B, and 3 drilled in support of the Exploratory Studies Facility (ESF) at Yucca Mountain. The holes penetrated the Timber Mountain tuff and two thermal/mechanical units of the Paintbrush tuff. The thermal/mechanical stratigraphy was defined by Ortiz to group rock horizons of similar properties for the purpose of simplifying modeling efforts. The relationship between the geologic stratigraphy and the thermal/mechanical stratigraphy for each borehole is presented. The tuff samples in this study have a wide range of welding characteristics (usually reflected in sample porosity), and a smaller range of mineralogy and petrology characteristics. Generally, the samples are silicic, ash-fall tuffs that exhibit large variability in their elastic and strength properties.

Experimental results are presented for bulk and mechanical properties measurements on specimens of the Paintbrush tuff recovered from boreholes UE25 NRG-4 and -5, at Yucca Mountain, Nevada. Measurements have been performed on three thermal/mechanical units, PTn, TSwl, and TSw2. On each specimen the following bulk properties have been reported: dry bulk density, saturated bulk density, average grain density, and porosity. Unconfined compression to failure, confined compression to failure, and indirect tensile strength tests were performed on selected specimens recovered from the boreholes. In addition, compressional and shear wave velocities were measured on specimens designated for unconfined compression and confined compression experiments. Measurements were conducted at room temperature on nominally water-saturated specimens. The nominal rate for the fracture experiments was 10{sup -5}s{sup -1}.

Sandia National Laboratories, New Mexico (SNL/NM) is managed and operated by Sandia Corporation, a Lockheed Martin Company. SNL/NM is located on land owned by the U.S. Department of Energy (DOE) within the boundaries of the Kirtland Air Force Base (KAFB) in Albuquerque, New Mexico. The major responsibilities of SNL/NM are the support of national security and energy projects. Low-level radioactive waste (LLW) is generated by some of the activities performed at SNL/NM in support of the DOE. This report describes potential environmental effects of the shipments of low-level radioactive wastes to other sites.

Ambient air samples were taken at two locations in the East Mountain Area in conjunction with thermal testing at the Lurance Canyon Burn Site (LCBS). The samples were taken to provide measurements of particulate matter with a diameter less than or equal to 10 micrometers (PM{sub 10}) and volatile organic compounds (VOCs). This report summarizes the results of the sampling performed in 1995. The results from small-scale testing performed to determine the potentially produced air pollutants in the thermal tests are included in this report. Analytical results indicate few samples produced measurable concentrations of pollutants believed to be produced by thermal testing. Recommendations for future air sampling in the East Mountain Area are also noted.

One of the most common oil-field treatments is hot oiling to remove paraffin from wells. Even though the practice is common, the thermal effectiveness of the process is not commonly understood. In order for producers to easily understand the thermodynamics of hot oiling, a simple tool is needed for estimating downhole temperatures. Such a tool has been developed that was distributed as a compiled, public-domain-software spreadsheet. That spreadsheet has evolved into an interactive from on the World Wide Web and has been adapted into a Windows{trademark} program by Petrolite, St. Louis MO. The development of such a tools was facilitated by expressing downhole temperatures in terms of analytic formulas. Considerable algebraic work is required to develop such formulas. Also, the data describing hot oiling is customarily a mixture of practical units that must be converted to a consistent set of units. To facilitate the algebraic manipulations and to assure unit conversions are correct, during development parallel calculations were made using the spreadsheet and a symbolic mathematics program. Derivation of the formulas considered falling film flow in the annulus and started from the transient differential equations so that the effects of the heat capacity of the tubing and casing could be included. While this approach to developing a software product does not have the power and sophistication of a finite element or difference code, it produces a user friendly product that implements the equations solved with a minimum potential for bugs. This allows emphasis in development of the product to be placed on the physics.

This paper considers the protein structure prediction problem for lattice and off-lattice protein folding models that explicitly represent side chains. Lattice models of proteins have proven extremely useful tools for reasoning about protein folding in unrestricted continuous space through analogy. This paper provides the first illustration of how rigorous algorithmic analyses of lattice models can lead to rigorous algorithmic analyses of off-lattice models. The authors consider two side chain models: a lattice model that generalizes the HP model (Dill 85) to explicitly represent side chains on the cubic lattice, and a new off-lattice model, the HP Tangent Spheres Side Chain model (HP-TSSC), that generalizes this model further by representing the backbone and side chains of proteins with tangent spheres. They describe algorithms for both of these models with mathematically guaranteed error bounds. In particular, the authors describe a linear time performance guaranteed approximation algorithm for the HP side chain model that constructs conformations whose energy is better than 865 of optimal in a face centered cubic lattice, and they demonstrate how this provides a 70% performance guarantee for the HP-TSSC model. This is the first algorithm in the literature for off-lattice protein structure prediction that has a rigorous performance guarantee. The analysis of the HP-TSSC model builds off of the work of Dancik and Hannenhalli who have developed a 16/30 approximation algorithm for the HP model on the hexagonal close packed lattice. Further, the analysis provides a mathematical methodology for transferring performance guarantees on lattices to off-lattice models. These results partially answer the open question of Karplus et al. concerning the complexity of protein folding models that include side chains.