Publications

Yucca Mountain, Nevada is a potential site for a high-level radioactive-waste repository. Uncertainty and sensitivity analyses were performed to estimate critical factors in the performance of the site with respect to a criterion in terms of pre-waste-emplacement ground-water travel time. The degree of failure in the analytical model to meet the criterion is sensitive to the estimate of fracture porosity in the upper welded unit of the problem domain. Fracture porosity is derived from a number of more fundamental measurements including fracture frequency, fracture orientation, and the moisture-retention characteristic inferred for the fracture domain.

The potential repository system is intended to isolate high-level radioactive waste at Yucca Mountain according to the performance objective - 10 CFR 60.112. One subsystem that may contribute to achieving this objective is the sealing subsystem. This subsystem is comprised of sealing components in the shafts, ramps, underground network of drifts, and the exploratory boreholes. Sealing components can be rigid, as in the case of a shaft seal, or can be more compressible, as in the case of drift fill comprised of mined rockfill. This paper presents the preliminary seismic response of discrete sealing components in welded and nonwelded tuff. Special consideration is given to evaluating the stress in the seal, and the behavior of the interface between the seal and the rock. The seismic responses are computed using both static and dynamic analyses. Also presented is an evaluation of the maximum seismic response encountered by a drift seal with respect to the angle of incidence of the seismic wave. Mitigation strategies and seismic design considerations are proposed which can potentially enhance the overall response of the sealing component and subsequently, the performance of the overall repository system.

The unique attributes of the field ion microscope have enabled researchers to obtain detailed information on the diffusion of individual atoms and the nucléation of small clusters on metal surfaces. In this article I describe the experimental methods used in field ion microscope studies of these processes and discuss recent results relating to the discovery of novel diffusion modes and unexpected cluster configurations on fee metal surfaces. © 1993 The Japan Society of Applied Physics.

This report contains an outline of the Solar Thermal Design Assistance Center's (STDAC) major activities and accomplishments in Fiscal Year 1992 (FY92). The report describes the resources allocated to fund STDAC and the personnel needed to carry out STDAC activities and accomplishments. It also contains a comprehensive list of persons that called STDAC for consultation in FY92.

A series of constant strain rate, unconfined compression experiments was performed on saturated welded tuff specimens collected from Busted Butte near Yucca Mountain, Nevada. Twenty specimens were loaded to failure at strain rates ranging from 10{sup {minus}9}s{sup {minus}1} to 10{sup {minus}3}s{sup {minus}1}, under ambient pressure and temperature conditions. The strength of the specimens showed a continuous decrease with decreasing strain rate between 10{sup {minus}9} s{sup {minus}1} and 10{sup {minus}5} s{sup {minus}1}. At the highest strain rate, 10{sup {minus}3} s{sup {minus}1}, strengths were less than those observed at 10{sup {minus}5} s{sup {minus}1}, likely due to hydrofracturing within the specimen at rapid loading rates. Reduction in strength, corresponding to the decrease in strain rate, is explained in terms of stress corrosion cracking. A detailed examination of six specimens tested at a strain rate of 10{sup {minus}9} s{sup {minus}1}, using acoustic wave velocities and CT scans, shows a correlation between the nature of the microstructure of the specimens and the observed strengths and elastic moduli.

Pore scale invasion percolation theory is modified for imbibition of.wetting fluids into fractures. The effects of gravity, local aperture field geometry, and local in-plane air/water interfacial curvatureare included in the calculation of aperture filling potential which controls wetted structure growth within the fracture. The inclusion of gravity yields fingers oriented in the direction of the gravitational gradient. These fingers widen and tend to meander and branch more as the gravitational gradient decreases. In-plane interfacial curvature also greatly affects the wetted structure in both horizontal and nonhorizontal fractures causing the formation of macroscopic wetting fronts. The modified percolation model is used to simulate imbibition into an analogue rough-walled fracture where both fingering and horizontal imbibition experiments were previously conducted. Comparison of numerical and experimental results showed reasonably good agreement. This process oriented physical and numerical modeling is-a necessary step toward including gravity-driven fingering in models of flow and transport through unsaturated, fractured rock.

Paramount to the modeling of unsaturated flow and transport through fractured porous media is a clear understanding of the processes controlling fracture-matrix interaction. As a first step toward such an understanding, two preliminary experiments have been performed to investigate the influence of matrix imbibition on water percolation through unsaturated fractures in the plane normal to the fracture. Test systems consisted of thin slabs of either tuff or an analog material cut by a single vertical fracture into which a constant fluid flux was introduced. Transient moisture content and solute concentration fields were imaged by means of x-ray absorption. Flow fields associated with the two different media were significantly different owing to differences in material properties relative to the imposed flux. Richards` equation was found to be a valid means of modeling the imbibition of water into the tuff matrix from a saturated fracture for the current experiment.

A set of detailed geostatistical simulations of porosity has been produced for a layered stratigraphic sequence of welded and nonwelded volcanic tuffs at Yucca Mountain, Nevada. The simulations are produced using a composite. model of spatial continuity and they are highly conditioned to abundant drill hole (core) information. A set of derivative simulations of saturated hydraulic conductivity has been produced, in the absence of conditioning data, using a cross-variable relationship developed from similar data elsewhere. The detailed simulations reproduce both the major stratigraphic units and finer scale layering indicated by the drill hole data. These simulations have been scaled up several order of magnitude to represent block-scale effective hydrologic properties suitable for use in numerical modeling of groundwater flow and transport. The upscaling process involves the reformulation of a previously reported method that iteratively adapts an initial arbitrary grid to ``homogenize`` the detailed hydraulic properties contained within the adjusted cell limits and to minimize the size of cell in highly heterogeneous regions. Although the computation of the block-effective property involves simple numerical averaging, the blocks over which these averages are computed are relatively homogeneous, which reduces the numerical difficulties involved in averaging non-additive properties, such as permeability. The entire process of simulation and upscaling is rapid and computationally efficient compared with alterative techniques. It is thus suitable for the Monte Carlo evaluation of the uncertainty in site characterization as it affects the results of groundwater flow and transport calculations.

Hydrologic properties have been measured on outcrop samples taken from a detailed, two-dimension grid covering a 1.4 km outcrop exposure of the 10-m thick non-welded-to-welded, shardy base microstratigraphic unit of the Tiva Canyon Member of the Miocene Paintbrush Tuff at Yucca Mountain, Nevada. These data allow quantification of spatial trends in rock matrix properties that exist in this important hydrologic unit. Geologic investigation, combined with statistical and geostatistical analyses of the numerical data, indicates that spatial variability of matrix properties is related to deterministic geologic processes that operated throughout the region. Linear vertical trends in hydrologic properties are strongly developed in the shardy base microstratigraphic unit, and they are more accurately modeled using the concept of a thickness-normalized stratigraphic elevation within the unit, rather than absolute elevation. Hydrologic properties appear to be correlated over distances of 0.25 to 0.3 of the unit thickness after removing the deterministic vertical trend. The use of stratigraphic elevation allows scaling of identified trends by unit thickness which may be of particular importance in a basal, topography-blanketing unit such as this one. Horizontal changes in hydrologic properties do not appear to form obvious trends within the limited lateral geographic extent of the ash-flow environment that was examined. Matrix properties appear to be correlated horizontally over distances between 100 and 400 m. The existence and quantitative description of these trends and patterns of vertical spatial continuity should increase confidence in models of hydrologic properties and groundwater flow in this area that may be constructed to support the design of a potential high-level nuclear waste repository at Yucca Mountain.

This paper presents a method of estimating the rock mass properties for the welded and nonwelded tuffs based on currently available information on intact rock and joint characteristics at the Yucca Mountain site. Variability of the expected ground conditions at the potential repository horizon (the TSw2 thermomechanical unit) and in the Calico Hills nonwelded tuffs is accommodated by defining five rock mass quality categories in each unit based upon assumed and observed distributions of the data.

A numerical approach for modeling unsaturated flow is developed for heterogeneous simulations of fractured tuff generated using a geostatistical method. Cross correlations of hydrologic properties and upscaling of moisture retention curves is discussed. The approach is demonstrated for a study of infiltration at Yucca Mountain.

The regulations that currently govern repositories for spent fuel and high-level waste require demonstrations that are sometimes described as impossible to make. To make them will require an understanding of the current and the future phenomena at repository sites; it will also require credible estimates of the probabilities that the phenomena will occur in the distant future. Experts in many fields{emdash}earth sciences, statistics, numerical modeling, and the law{emdash}have questioned whether any amount of data collection can allow modelers to meet these requirements with enough confidence to satisfy the regulators. In recent years some performance assessments have begun to shed light on this question because they use results of actual site investigations. Although these studies do not settle the question definitively, a review of a recent total-system assessment suggests that compliance may be possible to demonstrate. The review also suggests, however, that the demonstration can be only at the ``reasonable`` levels of assurance mentioned, but not defined, in the regulations.

Previous laboratory investigations of tuff have shown that porosity has a dominant, general effect on mechanical properties. As a result, it is very important for the interpretation of mechanical property data that porosity is measured on each sample tested. Porosity alone, however, does not address all of the issues important to mechanical behavior. Variability in size and distribution of pore space produces significantly different mechanical properties. A nondestructive technique for characterizing the internal structure of the sample prior to testing is being developed and the results are being analyzed. The information obtained from this technique can help in both qualitative and quantitative interpretation of test results.

In situ thermomechanical experiments are planned as part of the Yucca Mountain Site Characterization Project that require instruments to measure stress and displacement at temperatures that exceed the typical specifications of existing geotechnical instruments. A high degree of instrument reliability will also be required to satisfy the objectives of the experiments, therefore a study was undertaken to identify areas where improvement in instrument performance was required. A preliminary list of instruments required for the experiments was developed, based on existing test planning and analysis. Projected temperature requirements were compared to specifications of existing instruments to identify instrumentation development needs. Different instrument technologies, not currently employed in geotechnical instrumentation, were reviewed to identify potential improvements of existing designs for the high temperature environment. Technologies with strong potentials to improve instrument performance with relatively high reliability include graphite fiber composite materials, fiber optics, and video imagery.

As a follow-on to Sandia`s 1991 preliminary total-system performance assessment of the Yucca Mountain site, this paper presents results of some sensitivity analyses that were done using results from the 1991 study. Two conceptual models of unsaturated-zone flow and transport at Yucca Mountain were included in the study, including both aqueous and gaseous releases. The sensitivities are quite different for the two models. For the composite-porosity model, the results are most sensitive to groundwater percolation flux, gaseous transport time, container lifetime, and fuel-matrix-alteration rate. For the weeps model, the results are most sensitive to parameters used to characterize fracture flow (fracture aperture and fracture connectivity) and infiltration (percolation flux and weep-episode factor).

The event-tree method of scenario construction has been chosen for the Yucca Mountain performance assessment. Its applicability and suitability to the problem are discussed and compared with those of the Nuclear Regulatory Commission (NRC) method. The event-tree method is appropriate for an incompletely characterized site, where there must be an evolving understanding, over time, of the processes at work, for a site that may require analysis of details in specific context, and when the scenario functions to guide site characterization. Anticipating the eventual requirement for using the NRC method, we show that the event-tree method can be translated to the NRC format after final scenario screening.

Chemical vapor deposition (CVD) is a widely used method for depositing thin films of a variety of materials. Applications of CVD range from the fabrication of microelectronic devices to the deposition of protective coatings. New CVD processes are increasingly complex, with stringent requirements that make it more difficult to commercialize them in a timely fashion. However, a clear understanding of the fundamental science underlying a CVD process, as expressed through computer models, can substantially shorten the time required for reactor and process development. Research scientists at Sandia use a wide range of experimental and theoretical techniques for investigating the science of CVD. Experimental tools include optical probes for gas-phase and surface processes, a range of surface analytic techniques, molecular beam methods for gas/surface kinetics, flow visualization techniques and state-of-the-art crystal growth reactors. The theoretical strategy uses a structured approach to describe the coupled gas-phase and gas-surface chemistry, fluid dynamics, heat and mass transfer of a CVD process. The software used to describe chemical reaction mechanisms is easily adapted to codes that model a variety of reactor geometries. Carefully chosen experiments provide critical information on the chemical species, gas temperatures and flows that are necessary for model development and validation. This brochure provides basic information on Sandia`s capabilities in the physical and chemical sciences of CVD and related materials processing technologies. It contains a brief description of the major scientific and technical capabilities of the CVD staff and facilities, and a brief discussion of the approach that the staff uses to advance the scientific understanding of CVD processes.

Photovoltaic (PV) systems offer a cost-effective solution to provide electrical power for a wide variety of applications, with battery performance playing a major role in their success. This paper presents some of the results of an industry meeting regarding battery specifications and ratings that photovoltaic system designers require, but do not typically have available to them. Communications between the PV industry and the battery industry regarding appropriate specifications have been uncoordinated and poor in the past. This paper also discusses the effort under way involving the PV industry and battery manufacturers, and provides a working draft of specifications to develop and outline the information sorely needed on batteries. The development of this information is referred to as ``Application Notes for Batteries in Photovoltaic Systems.`` The content of these ``notes`` has been compiled from various sources, including the input from the results of a survey on battery use in the photovoltaic industry. Only lead-acid batteries are discussed

In one design of molten-salt central receivers, the molten salt flows in a serpentine path, down one panel of tubes then up the next and down again continuing in this fashion through the receiver. There have been concerns about this design because in the down flow sections, the heat flux incident on the tubes can cause flow instability since the flow is in direct opposition to the buoyant forces. In extreme cases the buoyant forces can cause flow stagnation or reversal. An analysis of flow stability within individual tubes and down flow sections of receiver panels is presented. When the partial derivative of the pressure drop with respect to mass flow rate is negative ({partial_derivative}{Delta}P/{partial_derivative}{sup {lg_bullet}} < 0), the flow is unstable and could cause serious damage to the receiver. Stability maps are developed that show safe operating regimes where inertial forces dominate over buoyant forces. The data is then normalized using the Grashof and Reynolds numbers.

United States Department of Energy has established its first Advanced Research Objective in the Solids Transport Program. The scientific, engineering, and management goals are discussed in some detail. Scientific progress to date is summarized. Comments are made on the technical direction of further Advanced Research Objectives.

We have developed a Li/SOCl{sub 2} ``D`` cell for applications requiring 10 to 15 years life at very low drain rates, typically less than 150 {mu}A. Maximizing cell safety and reliability, while delivering very good energy density, have been the goals of our study. We have achieved these goals by designing the cell to be application specific. The low-rate cell has been optimized to deliver up to 16 Ah at drain rates of less than 70 mA. By virtue of its low surface area, 145 cm{sub 2}, the cell has demonstrated excellent safety behavior. Safety testing has been performed on individual cells as well as on two-cell and four-cell batteries. Single cells did not vent when short-circuited. We were able to produce benign venting in a two cell string, but only when the string was partially discharged before shorting. The vent mechanism is a 300 psi rupture pressure burst disc manufactured by BS&B Safety Systems. We define benign venting as full opening of the 3/8 in. dia vent hole without deformation of the case. Material is expelled from the cell without flame, and the cell stack remains largely intact. We have not produced venting of the Sandia-designed low rate cell under any other abuse test conditions. The vent functions as an ultimate safety mechanism in the case of severe abuse, but resistance to venting under normal use and mild abuse conditions is key to the achievement of high reliability.

A new class of ion-exchange materials that can selectively separate low parts per million level concentrations of Cs{sup +} from 3--6 molar concentrations of Na{sup +} over a wide pH range has recently been developed as a result of a collaborative effort between Sandia National Laboratories and Texas A&M University. The materials, called crystalline silicotitanates, show potential for application in the treatment of aqueous nuclear waste solutions.

In order to develop a procedure for measuring cation diffusion coefficients below 1000{degrees}C, we have examined the suitability of several diffusion couple configurations involving single crystals of garnet. Initial experiments using an enriched {sup 25}MgCl{sup 2} proved ineffective in providing a uniform and coherent surface for analysis by ion microprobe. A technique was developed using thin film deposition. Thin films ({approximately} 1000 {Angstrom}) of MgO{sub x} (x < 1) can be applied to polished mineral surfaces by evaporating MgO powder under high vacuum with a thermal-resistance strip heater. Thermal resistance evaporation is efficient. Samples of single crystal grossular and pyrope garnets with thin films of MgO, as created by these techniques, were annealed for various times at 800, 900, and 1000{degrees}C, at several log fO{sub 2} values, and 1 atm. Optical, SEM, and ion microprobe analyses reveal no disruption of the interface. Profiles of elemental counts vs depth exhibit expected patterns going through the thin film into the garnet substrate. Our experimental matrix of garnet diffusion runs includes over 60 cut and polished crystals of pyrope composition that are being run at various oxygen fugacity conditions from 600 to 1000{degrees}C.

The Los Alamos National Laboratory (LANL) Mechanical Engineering and Electronics Division, in partnership with Sandia National Laboratories and Programmed Composites, is advancing the development of thin-walled, high modulus short-fiber compression-molded composite materials fabrication. In this paper, we investigate component uniformity, structural integrity, thermal conductivity, and radiation resistance; discuss the scanning-electron microscopic inspection of the graphite fiber distribution and orientation, and describe the process used in selecting the reinforcement fiber length and modulus and for choosing the hydrophobic, cyanate-ester resin.

During the last two decades there has been considerable interest in developing alternatives to conventional chemical propulsion for space missions. Laser propulsion has been identified as a serious contender for the task of inexpensively delivering small payloads to low-earth orbit. Recent advances in the development of lasers powered directly by nuclear reaction products offer the potential for new propulsion methods, namely, reactor-laser propulsion. Such systems would allow ``nuclear propulsion`` without placing nuclear systems in space.

Alternate organometallic Sb sources are being investigated to improve the characteristics of InSb grown by MOCVD. InSb grown using trimethylindium (TMIn) and trimethylantimony (TMSb) or triethylantimony (TESb) yielded similar quality materials under similar growth conditions. InSb grown using triethylindium (TEIn) and TESB under similar growth conditions yielded very poor quality n-type material. Three new organometallic Sb sources, triisopropyl-antimony (TIPSb), tris(dimethylamino)antimony (TDMASb), and tertiarybutyldimethylantimony (TBDMSb) are being investigated. Growth of InSb using TIPSb, TDMASb, or TBDMSb and TMIn was investigated over 350 to 475{degrees}C. InSb grown from TDMASb had similar properties to InSb grown from TMIn and TMSb when using a similar temperature and V/III ratio range. Growth rates of InSb using TMIn and either TIPSb or TBDMSb at temperatures {le} 425{degrees}C were proportional to both TMIn flow rate and temperature. Surface morphology of InSb grown using either TIPSb or TBDMSb was rough for growth temperatures {le} 425{degrees}C; this may be due to complex decomposition and methyl groups on surface. The InSb with the highest mobility was grown at 400{degrees}C and a V/III ratio of 3 using TIPSb. It was n-type with a carrier concentration of 2.5 {times} 10{sup 15} cm{sup {minus}3} and a mobility of 78,160 cm{sup 2}/Vs at 77 K. Both n- and p-type InSb were grown using TBDMSb with mobilities up to 67,530 and 7773 cm{sup 2}/Vs, respectively at 77 K. Mobility for InSb using either TIPSb or TBDMSb was optimized by going to lower temperatures, pressures, V/III ratios; however, surface morphology improved with higher temperature, pressure, V/III ratio. High mobility InSb with smooth surfaces at T {le} 425{degrees}C was not obtained with TIPSb or TBDMSb and TMIn.

We present the use of an STM to make quantitative observations of time-dependent mass flow associated with the decay of two-dimensional clusters on the Au(lll) surface. When formed and observed in air, layered islands with well-defined edges located on larger terraces are generally found to decay in such a way that their areas decrease linearly in time over periods ranging from minutes to several hours depending on the island size. This is in contrast to the behavior of similar features formed and observed under ultra high vacuum conditions, which do not appear to decay over experimental periods of several days. The linear decay is consistent with models that have been used previously to describe growth of 2-dimensional clusters on surfaces. We discuss possible decay mechanisms`, and the role that adsorbates may play in influencing the decay.

In support of the UST, WeDID, VOC/Non-Arid, and VOC/Arid, and VOC/Arid Integrated Demonstrations, organic contaminants and nitrates in Hanford Underground Storage Tank (UST) wastes, polymeric organics in weapon components, and chlorocarbon soil contaminants have been destroyed by exposure to high-temperature steam during bench tests with a quartz reactor and full-scale tests that used the Synthetica Detoxifier, a commercial one-ton-per-day steam reforming waste destruction system. Reactivation of Granular Activated Carbon (GAC) in the Detoxifier and Thermal Gravimetric Analyses (TGA) of the decomposition of sodium nitrate have also been performed.

We have successfully grown ZnMnTe alloys by molecular beam epitaxy using GaAs as a substrate. Bulk MnTe has the wurtzite crystal structure but the structural phase of the material was confirmed to be zinc-blende by standard {theta}-2{theta} x-ray diffraction techniques. The composition was also determined using x-ray diffraction techniques. Manganese concentration was also estimated from magnetization measurements taken as a function of temperature. Magnetoluminescence studies were performed at 1.4K on the acceptor-bound exciton in the semimagnetic semiconductor ZnMnTe alloys. As expected, the photoluminescence peak energy decreased with increasing magnetic field.

At some landfills, hazardous wastes were placed into disposal pits with other waste oils. Volatile organic wastes, such as cleaning solvents, when combined with oil are much more difficult to remove from the soils because the oil makes the volatile organic chemical evaporate much slower. The typical vacuum extraction remediation method could become a lengthy campaign. Since all chemicals evaporate faster when they are heated, if the contaminated soil could be heated, the chemicals would be easier to remove from the soil. By using heating techniques developed by the Oil and Gas Industry to enhance the removal of oil and gas resources from the soil, the problem of removing contamination from the soils could be solved. The Thermal Enhanced Vapor Extraction System (TEVES) demonstration will combine vacuum vapor extraction technology with powerline frequency soil heating and radiofrequency soil heating to accelerate the soil decontamination process. The premise that soil heating technology can actually reduce the costs of soil decontamination is complicated by the high capital costs of the soil heating equipment and the cost of electrode installation. By performing this field demonstration, Sandia will be able to collect the information needed to see if this new technology will improve the decontamination of soils.

Sandia National Laboratories is a large multiprogram Research and Development laboratory which is operated by a contractor for the US Department of Energy. In the Laboratories, lasers are both the subject of research and the tools that are used in other research, development, and testing activities. Since 1979, laser safety training has been the primary focus of the Laboratories` laser safety program. Approximately 1 100 personnel have been trained in formal courses during that time period. The formal course, presented on site by a contractor, consists of two full days of instruction. The course contents include the following topics: Laser technology and safety overview; Federal and ANSI laser standards summaries; Biological effects of laser radiation; Classification of lasers; Laser hazard analysis; Review of ANSI Z136.1 control measures; Laser eye protection. Recent emphasis on regulatory requirements, conduct of operations, and quality management has revealed a need to change the laser safety training curriculum. A new course for users of low power lasers (Class 2 and 3a) is being developed. A refresher course, a management awareness (self-study) course, and major changes in the current course are planned.

Short communication.

A solar photocatalytic process has been under development at both Sandia National Laboratories and the National Renewable Energy Laboratory (formerly the Solar Energy Research Institute). This process uses solar ultraviolet light to activate a titanium dioxide catalyst which oxidizes organic contaminants in water. In the summer of 1991, a solar photocatalytic detoxification of water system was installed and tested at a California Superfund Site located at Lawrence Livermore National Laboratory. The site was designated a Superfund Site because of widespread groundwater contamination which resulted from the release of chlorinated solvents, principally trichloroethylene, when the site was a Naval Air Station in the early 1940s. The objectives of these experiments were to measure the effects of process variables and the process efficiency in an actual remediation setting, to collect experimental data and operating experience in photocatalytic oxidation of organic contaminants, to develop accurate models of the system operation and to develop control strategies.

We have developed a video detection algorithm for measuring the residue left on a printed circuit board after a soldering process. Oblique lighting improves the contrast between the residue and the board substrate, but also introduces an illumination gradient. The algorithm uses the Boundary Contour System/Feature Contour System to produce an idealized clean board image by discounting the illuminant, detecting trace boundaries, and filling the trace and substrate regions. The algorithm then combines the original input image and ideal image using mathematical models of the normal and inverse Weber Law to enhance the residue on the traces and substrate. The paper includes results for a clean board and one with residue.

The Materials Interface Interaction Tests (MIIT) program involves the comparative performance-evaluation testing of multiple US and foreign nuclear waste glasses (nonradioactive), potential canister and overpack metals, brine, and geologic materials in the rock salt repository environment at the Waste Isolation Pilot Plant (WIPP) facility. We emplaced about 2000 materials specimens onto fiftn, separate test assemblies and exposed them to a heated, salt-brine environment at the WIPP for multi-year periods. We successfully terminated the in situ conduct of the MIIT in July 1991, after five years of testing, and retrieved all samples for posttest laboratory analyses. These 5-year glass and metal samples, along with samples previously retrieved after 0.5, 1, and 2 years, are being analyzed in multiple international laboratories, in a cooperative testing effort. Individual test participants will present available laboratory results, and interpretations, on MIIT specimens in this workshop. Our focus in this paper is to summarize technical details and repository-relevant observations on the in situ conduct, sampling, and termination operations of the MIIT experimental program. Such information should be useful for the interpretation of the laboratory-based analyses. This information also will be relevant and instructive for other organizations contemplating, planning, or conducting additional materials-related, in situ tests.

A comparison between numerical calculations with use of commercial thermal analysis software packages and experimental data simulating a horizontally oriented spent fuel rod array was performed. Twelve cases were analyzed using air and helium for the fill gas, with three different heat dissipation levels. The numerically predicted temperatures are higher than the experimental data for all levels of heat dissipation with air as the fill gas. The temperature differences are 4{degree}C and 23{degree}C for the low heat dissipation and high heat dissipation, respectively. The temperature predictions using helium as a fill gas are lower than the experimental data for the low and medium heat dissipation levels. The temperature predictions are 1{degree}C and 6{degree}C lower than the experimental data for the low and medium heat dissipation, respectively. For the high heat dissipation level, the temperature predictions are 16{degree}C higher than the experimental data. Differences between the predicted and experimental temperatures can be attributed to several factors. These factors include experimental uncertainty in the temperature and heat dissipation measurements, actual convection effects not included in the model, and axial heat flow in the experimental data. This work demonstrates that horizontally oriented spent fuel rod surface temperature predictions can be made using existing commercial software packages. This work also shows that end effects, such as axial heat transfer through the spent fuel rods, will be increasingly important as the amount of dissipated heat increases.

Magnetic force microscopy (MFM) has been applied to image currents in internal IC conductors. We present a model for the MFM imaging of IC currents, describe MFM signal generation, and demonstrate the ability to analyze current direction and magnitude with a sensitivity of {approximately} 1 mA dc and {approximately} 1 {mu}A ac. Our experimental results are a significant improvement on the 100 mA ac resolution previously reported using an electron beam to detect IC currents [1].

The Waste Isolation Pilot Plant: (WIPP) in southeastern New Mexico is being developed by the US Department of Energy as a disposal facility for transuranic waste. In support of this project, Sandia National Laboratories is conducting an ongoing performance assessment (PA) for the WIPP. The ordered triple- representation for risk proposed by Kaplan and Garrick is used to provide a clear conceptual structure for this PA. This presentation describes how the preceding representation provides a basis in the WIPP PA for (1) the definition of scenarios and the calculation of scenario probabilities and consequences, (2) the separation of subjective and stochastic uncertainties, (3) the construction of the complementary cumulative distribution functions required in comparisons with the US Environmental Protection Agency`s standard for the geologic disposal of radioactive waste (i.e., 40 CFR Part 191, Subpart B), and (4) the performance of uncertainty and sensitivity studies. Results obtained in a preliminary PA for the WIPP completed in December of 1991 are used for illustration.

Short communication.

As applications for hybrid circuits and multichip modules create demand for higher density circuits and higher power components, new substrate materials are required to deal with the heat generated on the circuit. Sandia National Laboratories is developing diamond substrate technology to meet the requirements of high thermal conductivity. Thin film processes were developed and characterized to delineate conductor-resistor networks on free standing diamond substrates having fine line gold conductors and low and high sheet resistivity resistors. Thin film hybrid circuit technology was developed on CVD-processed, polycrystalline diamond substrates having as-deposited surface finishes as well as those with polished surfaces. Conductors were defined by pattern plating gold and resistors were processed from sputtered tantalum nitride films which were deposited to sheet resistivities of 5 and/or 100 ohms per square. Resistor films on diamond substrates were evaluated for Temperature Coefficient of Resistance (TCR), stability with time and temperature, and trimmability using YAG laser processing. Plated gold conductors were patterned on diamond to feature sizes of 25 microns and successfully tested for adhesion and bondability. Advanced YAG laser trimming techniques were developed to allow resistor trims on both low and high value resistors to within 1% of desip value while maintaining required resistor stability, new trim techniques were needed to offset the carbonization of diamond in the laser trim area. Reliability studies were carried out on the diamond thin film networks which showed them to compare favorably with the same thin film technology on alumina substrates.

Photocreation mechanisms and properties of nitrogen dangling bonds in amorphous hydrogenated silicon nitride (a-SiN{sub x}:H) thin films are investigated. We find that the creation kinetics are strongly dependent on the post-deposition anneal; this thermal process can be described by a simple exponential function which yields an activation energy of 0.8 eV. The compositional dependence of the nitrogen dangling bond center suggests that its energy level lies close to the valence band edge, in agreement with theoretical calculations. This energy level position can explain why a-SiN{sub x}:H films often become conducting following a high post-deposition anneal.

Path planning needs to be fast to facilitate real-time robot programming. Unfortunately, current planning techniques are still too slow to be effective, as they often require several minutes, if not hours of computation. To overcome this difficulty, we present an adaptive algorithm that uses previous experience to speed up future performance. It is a learning algorithm suitable for incrementally-changing environments such as those encountered in manufacturing of evolving products and waste-site remediation. The algorithm extends our previous work for stationary environments in two directions: For minor environmental change, an object-attached experience abstraction scheme is introduced to increase the flexibility of the learned experience; for major environmental change, an on-demand experience repair scheme is also introduced to retain those experiences that remain valid and useful. In addition to presenting this algorithm, we identify three other variants with different repair strategies. To analyze the respective performance of these algorithms, we develop an analytic model that quantifies and relates training effort, experience value and utility, and environmental change through intuitive terms of energy and work. It is a general and simple model that should be very useful in characterizing other types of learning processes as well. Using this model, we formalize the concept of incremental change, and prove the optimality of our proposedalgorithm under such change. Empirically, we also characterize the performance curve of each variant, confirm our theoretical optimality results, and demonstrate the practicality of our algorithm.

A method of solving the two-phase fluid flow equations using a genetic algorithm on a NCUBE multiprocessor computer is presented. The topics discussed are the two-phase flow equations, the genetic representation of the unknowns, the fitness function, the genetic operators, and the implementation of the algorithm on the NCUBE computer. The efficiency of the implementation is investigated using a pipe blowdown problem. Effects of varying the genetic parameters and the number of processors are presented.

The restoration of environmentally contaminated sites at DOE facilities has become a major effort in the past several years. The variety of wastes involved and the differing characteristics have driven the development of new restoration and monitoring technologies. One of the new remediation technologies is being demonstrated at the Savannah River Site near Aiken, South Carolina. In conjunction with this demonstration, a new technology for site characterization and monitoring of the remediation process has been applied by Sandia National Laboratories.

We used surface-profile data taken with a noncontact laser profilometer to determine the aperture distribution within a natural fracture and found the surfaces and apertures to be isotropic. The aperture distribution could be described equally well by either a normal or a lognormal distribution, although we had to adjust the standard deviation to `fit` the data. The aperture spatial correlation varied over different areas of the fracture, with some areas being much more correlated U= others. The fracture surfaces did not have a single fractal dimension over all length scales, which implied that they were not self-similar. We approximated the saturated flow field in the fracture by solving a finite-difference discretization of the fluid-flow continuity equation in two dimensions. We then calculated tracer breakthrough curves using a particle-tracking method. comparing the breakthrough curves obtained using both coarse- and fine-resolution aperture data (0.5- and 0.05-mm spacing between points, respectively) over the same subset of the fracture domain suggests that the spacing between the aperture data points must be less than the correlation length to obtain accurate predictions of fluid flow and tracer transport. In the future, we will perform tracer experiments and numerical modeling studies to determine exactly how fine the aperture data resolution must be (relative to the correlation length) to obtain accurate predictions.

A method is described for parallelizing molecular dynamics (MD) simulations by block-decomposing the matrix of bonded and non-bonded force computations. It is particularly useful for organic simulations (polymers, proteins) because unlike spatial-decomposition methods, it requires no geometric information about the simulation domain. Because its communication cost scales as N/{radical}P. rather than N as in the all-to-all broadcast or ring-exchange techniques commonly used in this type of MD simulation, larger numbers of processors can be used effectively, yielding greater parallel speed-ups.

Two major initiatives are underway in the US that are creating a significant financial impact on both the US taxpayer and on users of electric power. First, the US Department of Energy (DOE) has been tasked with cleaning-up the defense complex. This task is managed under the direction of the Office of Environmental Restoration and Waste Management (EM) of the DOE. The waste that EM must address includes radioactive, hazardous, and mixed that consists of both radioactive and hazardous constituents. Second, the DOE is required by the Nuclear Waste Policy Act (NWPA) to take title to commercial nuclear spent fuel assemblies starting in 1998. The DOE Office of Civilian Radioactive Waste Management (OCRWM) was established to carry out this charter. Since a final repository is not scheduled for opening until 2010 at the earliest, the DOE is planning on providing a Monitored Retrievable Storage (MRS) facility for centralized storage to bridge the time gap between 1998 and 2010. The NWPA requires that nuclear utilities pay a fee into a specific fund that Congress uses to pay the DOE for the development of the MRS, the transportation system, and the repository. This fund, along with the EM budget, constitutes a multi-billion dollar effort to manage DOE nuclear waste and to store and dispose of commercial spent nuclear fuel. These two seemingly unrelated problems have aspects of commonality that can be considered for the benefit of both programs, the US taxpayer, and the utility rate payer. Both programs are the responsibility of the DOE, and both will require engineered packages for storage, transportation, and disposal of the EM waste and commercial spent fuel. Rather than using specialized systems for each step (storage, transport, and disposal), a concept for a Universal Container System has been developed that could potentially simplify the overall waste management system, reduce expensive handling operations, and reduce total system cost.

Inadvertent alloying of Cu braze metal can compromise metal/ceramic seals. Electron microprobe analyses have quantified alloying of Cu brazes in metal/ceramic feedthroughs. Pin material and processing parameters above 1084C both affect alloying levels. Using either Kovar or Ni-plated 316L stainless steel pins limits alloying compared to Palco pins. Minimizing the time during which the braze is molten also avoids excessive alloying. The original thickness of the Ni plating on the Mo-Mn metallization of the ceramic also influences the alloying content of these brazes. Metal/ceramic brazes made with long brazing cycles, Mo-Mn metallization, and Kovar components grow a layer of Mo{sub 6}(Fe{sub 3.5}CO{sub 3.5}){sub 7} on the metallization. Layer thicknesses observed do not appear to compromise joint integrity. Ni additions of approximately 10 and 20 wt.% to Cu apparently increases the stress required for stress relaxation during cooldown. to maintain creep rates required for stress relaxation during cooldown. Relative to unalloyed Cu, this strengthening effect tends to increase as temperature is decreased.

In this paper we investigate the applicability of the feature extraction mechanisms found in the neurophysiology of mammals to the problem of object recognition in synthetic aperture radar imagery. Our approach is to present multiple views of objects to be recognized to a two-stage self-organizing neural network architecture. The first stage, a two-layer Neocognitron, performs feature extraction in each layer The resulting feature vectors are presented to the second stage, an ART-2A classifier self-organizing neural network which clusters the features into multiple object categories. The feature extraction operators resulting from the self-organization process are compared to the feature extraction mechanisms found in the neurophysiology of vision. In a previous paper, the Neocognitron was trained on raw SAR imagery. The architecture was able to recognize a simulated vehicle at arbitrary azimuthal orientations at a single depression angle while rejecting clutter as well as other vehicles. Feature extraction on raw imagery yielded features that were robust but very difficult to interpret. In this paper we report the results of some new experiments in which the self-organization process is applied separately to shadow and bright returns from objects to be recognized. Feature extraction on shadow returns yield oriented contrast edge operators suggestive of bipartite simple cells observed in the striate cortex of mammals. Feature extraction on the specularity patterns in bright returns yield a collection of operators resembling a twodimensional Haar basis set. We compare the performance of the earlier two-stage neural network trained on raw imagery with a modified network using the new feature set.

The Mixed Waste Landfill Integrated Demonstration (MWLID) is testing noninvasive site characterization methods at several locations, including the Chemical Waste Landfill (CWL) at Sandia National Laboratories. The CWL comprises shallow, unlined pits that were used for the disposal of acids, oils, solvents, and inorganic compounds from 1962 until the CWL was closed in 1985. The soils of the landfills are alluvial, predominantly sand, gravels and cobbles with small quantities of silts and clays. The focus of this study is an unlined chromic acid pit (UCAP). The UCAP pit is rectangular (approximately 4 {times} 10 m), which reportedly received unknown volumes of chromium in the form of chromic acid (liquid) and other hazardous materials. At this location, we have demonstrated a continuous waveform (CW) system for site characterization. During this year, we will also utilize a crossborehole pulsed radar system. Both methods are sensitive to variations in either electrical conductivity or dielectric constant in the soils or host rock at a waste site. These earth properties are some of the most responsive geophysical indicators of metallic, acidic and water-based subsurface contaminants.

Using Saturn as a driver, we are pursuing both photoresonantly pumped and photoionization/recombination lasers. Our lasing targets are gas cells with thin windows that are pumped by a z pinch 2 cm away radiating 10 TW. In both schemes the lasant and gas fill is neon. To increase our chances of measuring the resonantly photopumped lasing transition we have introduced potassium into a sodium z pinch and have eliminated oxygen from the gas cell windows. We have measured the spatial dependence of ionization balance across the gas cell, and this measurement is consistent with propagation of a shock front across the gas cell target. We have measured blue-shifted satellites to several Li-like neon transitions that may indicate return-current driven jetting a high 1.5e8 cm/sec velocity. Using a gold z-pinch we have shown that key radiation is necessary to excite the He-like lines of neon. An attempt at a single shot gain measurement also indicates that radiation is not the only source of gas cell heating.

This paper presents a full-field dye concentration measurement technique that extends our experimental capabilities to the measurement of transient dye concentration fields within steady state flow fields under unsaturated or saturated conditions. Simple light absorption theory provides a basis for translating images into high resolution dye concentration fields. A series of dye pulse experiments that demonstrate the combined use of the full-field saturation and dye concentration techniques was conducted at four different degrees of saturation. Each of these experimental sequences was evaluated with respect to mass balance, the results being within 5% of the known dye mass input. An image windowing technique allowed us to see increased dispersion due to decreasing moisture content, tailing of concentration at the rear of the dye pulse and slight velocity changes of the dispersive front due to changes in moisture content. The exceptional resolution of dye concentration in space and time provided by this laboratory technique allows systematic experimentation for examining basic processes affecting solute transport within saturated/unsaturated porous media. Future challenges for this work will be to use these techniques to analyze more complex systems involving heterogeneities, scaling laws, and detailed investigations of the relationship between transverse and longitudinal dispersion in unsaturated media.

The Beam Characterization System is being employed at the Sandia`s National Solar Thermal Test Facility to characterize the optical performance of heliostats, point-focus solar collectors, and their optical sub-elements as part of the on-going task to develop solar thermal technologies. With this measurement system, images of concentrated solar flux are acquired using digital imaging and processed to obtain such measures of the collector`s optical performance as beam power, flux distribution, and beam diameter. Key system elements are a diffusely reflective target for imaging collector beams, meteorological instrumentation including a flux gauge to measure flux at one point in the beam, and a calibration technique to establish a pixel-intensity-to-flux-density conversion factor for the image. The system is employed in a variety of collector tests such as beam quality, tracking error, and wind effects. The paper describes the Beam Characterization System and its components and presents, for illustration, sample test results. An analysis of the Beam Characterization System`s sources of measurement error is presented. Lastly, measurement techniques that employ the BCS to align heliostats and to measure or estimate collector surface slope errors are described.

We have measured the laser emission spectra of several vertical cavity surface emitting lasers following pulsed laser excitation, with a time resolution of < 1 ps. Correlations between the observed pulse widths and cavity lifetimes were observed.

A fundamental concern in the design of the potential repository at Yucca Mountain. Nevada is the response of the host rock to the emplacement of heat-generating waste. The thermal perturbation of the rock mass has implications regarding the structural, hydrologic. and geochemical performance of the potential repository. The phenomenological coupling of many of these performance aspects makes repository thermal modeling a difficult task. For many of the more complex, coupled models, it is often necessary to reduce the geometry of the potential repository to a smeared heat-source approximation. Such simplifications have impacts on induced thermal profiles that in turn may influence other predicted responses through one- or two-way thermal couplings. The effect of waste employment layout on host-rock thermal was chosen as the primary emphasis of this study. Using a consistent set of modeling and input assumptions, far-field thermal response predictions made for discrete-source as well as plate source approximations of the repository geometry. Input values used in the simulations are consistent with a design-basis a real power density (APD) of 80 kW/acre as would be achieved assuming a 2010 emplacement start date, a levelized receipt schedule, and a limitation on available area as published in previous design studies. It was found that edge effects resulting from general repository layout have a significant influence on the shapes and extents of isothermal profiles, and should be accounted for in far-field modeling efforts.

The remand of the US Environmental Protection Agency`s long-term performance standards for radioactive-waste disposal provides an opportunity to suggest modifications that would make the regulation more defensible and remove inconsistencies yet retain the basic structure of the original rule. Proposed modifications are in three specific areas: release and dose limits, probabilistic containment requirements, and transuranic-waste disposal criteria. Examination of the modifications includes discussion of the alternatives, demonstration of methods of development and implementation, comparison of the characteristics, attributes, and deficiencies of possible options within each area, and analysis of the implications for performance assessments. An additional consideration is the impact on the entire regulation when developing or modifying the individual components of the radiological standards.

As part of the NRC-sponsored program to study the implications of Generic Issue 57, Effects of Fire Protection System Actuation on Safety-Related Equipment,'' a subtask was performed to evaluate the applicability of formal decision analysis methods to generic issues cost/benefit-type decisions and to apply these methods to the GI-57 results. In this report, the numerical results obtained from the analysis of three plants (two PWRs and one BWR) as developed in the technical resolution program for GI-57 were studied. For each plant, these results included a calculation of the person-REM averted due to various accident scenarios and various proposed modifications to mitigate the accident scenarios identified. These results were recomputed to break out the benefit in terms of contributions due to random event scenarios, fire event scenarios, and seismic event scenarios. Furthermore, the benefits associated with risk (in terms of person-REM) averted from earthquakes at three different seismic ground motion levels were separately considered. Given this data, formal decision methodologies involving decision trees, value functions, and utility functions were applied to this basic data. It is shown that the formal decision methodology can be applied at several different levels. Examples are given in which the decision between several retrofits is changed from that resulting from a simple cost/benefit-ratio criterion by virtue of the decision-makinger's expressed (and assumed) preferences.

This issue describes several innovative technologies in modern manufacturing. Methods in which the HIRCIS sensor may cut costs in precision machining are described. Computer models and experimental methods aid in the chemical vapor deposition of high-temperature coatings. Shared computer networks provide communication for interactive collaboration. Sol-gel processing of tailored thin films furnish low cost, high quality glass coatings at room temperature. Integrated circuit characterization tools and expertise are available to improve quality and reliability in the microelectronic industry.

This paper describes preliminary experiments to investigate electron-beam radiolysis of model compounds appropriate for crude oil spills on water or soil. Since no previous work in this area is known to exist, the rate of destruction of such concentrated organic materials in aqueous media is not known. The experiments conducted here were designed to provide preliminary estimates of the destruction rate and the estimated costs. Samples of model compounds were irradiated to dose levels up to 700 Mrad (H{sub 2}0) and the change in chemical composition was determined by mass spectrometry/gas chromatography and Fourier transform infrared spectroscopy. It was found that a dose of 700 Mrads reduced the liquid volume of the model compound by 60% and that the major effect of irradiation was the formation of long chain alkanes and dimethyl and ethyl benzenes. Under certain conditions a solid polymer was found to form. When alcohol was present in the model compound, additional products included small quantities of ethane diodic acid, butanol, butanediol, and various other alcohols. Further research is recommended to obtain a better analysis of the products, better values for the destruction rates, and better understanding of dose rate effects.

For nearly 10 years, the Gould Electronics, Incorporated manufacturing plant in Chandler, Arizona, has been a model of how medium-temperature solar thermal energy systems can produce economical industrial process heat (IPH). In 1982, a solar IPH system was designed and built on the site by Solar Kinetics, Inc. The system has remained in operation and continues to provide economical process heat for Gould`s copper foil manufacturing operation. System performance and availability has fluctuated over the years, reaching a low point in early 1990 when the system was nearly inoperative because of equipment reliability problems. Gould teamed with engineers from Sandia National Laboratories` (Sandia) Solar Thermal Design Assistance Center to develop a plan to solve the technical problems and refurbish the field. The IPH system is currently operating at over 90-percent equipment availability, returning to Gould a net energy cost savings on the order of $7,500 per month. This paper presents the history and operation of the system from the perspective of the end user and describes the phased upgrade program undertaken with Sandia to refurbish the system.

The Jet Propulsion Laboratory is developing a large space-truss to support a micro-precision interferometer. A finite element model will be used to design and place passive and active elements in the truss to suppress vibration. To improve the model`s predictive capability, it is desirable to identify uncertain structural parameters in the model by utilizing experimental modal data. Testing of both the components and the system was performed to obtain the data necessary to identify the structural parameters. Extracting a modal model, absent of bias errors, from measured data requires great care in test design and implementation. Testing procedures that are discussed include: verification of non-constraining shaker attachment, quantification of the non-linear structural response, and the design and effects of suspension systems used to simulate a free structure. In addition to these procedures, the accuracy of the measured frequency response functions are evaluated by comparing functions measured with random excitation, using various frequency resolutions, and with step sine excitation.

This publication presents information from Sandia laboratories concerning developments in the following areas: a miniaturized sensor system for the testing and analysis of hazardous wastes;a cross-well seismic receiver for petroleum deposit detection; and computer codes for designing dish-stirling sytems.

The design, calibration, and preliminary test results for an underwater shock gauge are presented. The active element is a 25-{mu}m thick polyvinylidene fluoride shock sensor providing rise times as short as 50 ns. Fast rise time is essential to accurate recording of shock pulses with durations of only a few microseconds. The piezoelectric polymer provides a self-generating pressure sensor requiring neither amplification nor additional active electronic circuitry. The gauge package is designed to minimize electromagnetic interference from the high-voltage fire set used to power the exploding bridge wire pressure source. The gauge package is constructed to withstand the initial water shock as well as subsequent reactions in the water that result in strong water motion and bubble generation. Thin-film diaphragm sensors are not sturdy enough to withstand this environment. Initial tests show that the gauge responds in 200 ns in water and that low-frequency response is sufficient to allow recording for at least 40 {mu}s after the initial shock arrival.

Performance and functionality increases in network environments have in the need for readily accessible mass storage. UNIX{reg_sign}-based networks and mass storage systems are providing the required connectivity and interoperability, however, how UNIX-based mass storage systems are being used is not well documented. This paper describes a study of the usage of the UNIX-based Network Storage Service at Sandia National Laboratories.

A discrete element computer program, DMC (Distinct-Motion Code), has been used for several years to simulate blasting-induced rock motion. Recent enhancements of DMC`s capabilities have included addition of an algorithm that couples together rock motion and gas flow. This allows the user to specify a particular explosive which also specifies equation-of-state and other parameters necessary to model explosive gas flow from the blastwell. Rock loading by the flowing gas is calculated automatically. The mechanism for calculating the rock loading is the subject of this paper. The rock motion effects the gas flow calculation by changing the porosity. DMC is currently being used on a SLTN SPARCstation 2 computer workstation.

Short communication.

Solder wettability of Class II environmentally exposed Cu substrates coated with an organic solderability preservative (OSP) is being investigated. The OSP coatings slightly retarded the wetting behavior of 60Sn-40Pb solder during baseline testing of unaged coupons. A nominal increase in wetting angle, or decrease in wettability, was observed on the inhibited surfaces, particularly when less active fluxes were used. Small increases in the wetting time and decreases in the wetting rate were also measured. Simulated accelerated aging tests are underway to determine the effects of aging in a typical indoor industrial environment on the solder wettability of OSP coated Cu.

Sandia operated by AT&T for the US Department of Energy. Sandia has a billion dollar annual budget and over 8,000 employees. Sandia`s main sites are in Albuquerque, New Mexico; Livermore, California; and Tonopah, Nevada. Sandia has a broad base of engineering and scientific skills that supports the whole product cycle from advanced R&D through manufacturing and end-user support. Sandia`s original mission was to develop the non-nuclear portion of nuclear weapons. In the 1970s, the mission was expanded to include technical work on conventional and alternative energy sources. Recently, the mission was further expanded to include technology transfer and US competitiveness. This report describes the activities in the Component Development and Engineering Support Division 2000 (indicated by the bold lines on the organization chart). Division 2000 develops electrical, electronic, optical, explosive, mechanical, and other components that are the core products of Sandia systems. The Division also develops advanced capabilities in CAD/CAE, test, nondestructive test, programming, reliability, failure analysis, and simulation that are part of the core services required by Sandia systems. For each of the core products and services described in this brochure, there is a corresponding set of science and engineering capabilities that are Sandia`s core competencies. Also, there are systems groups that use these core products and services to develop ultra-reliable systems for Sandia`s customers. Most of these groups have literature available describing their capabilities and expertise.

Nuclear power plants have experienced actuations of fire protection systems (FPSs) under conditions for which these systems were not intended to actuate. They have also experienced advertent actuations with the presence of a fire. These actuations have often damaged nearby plant equipment. A review of past occurrences of both types of such events on nuclear power plant safety has been performed. Thirteen different scenarios leading to actuation of fire protection systems due to a variety of causes were identified. These scenarios range from inadvertant actuation caused by human errors to hardware failures and include seismic root causes and seismic/fire interactions. A quantification of these thirteen scenarios, where applicable, was performed on a BWR4/MKI. This report estimates the contribution of FPS actuations to core damage frequency and to risk.

Data are presented from the Geomechanical Evaluation (first phase), a very large scale in situ test fielded underground at the Waste Isolation Pilot Plant (WIPP). These data include selected fielding information, test configuration, instrumentation activities, and comprehensive results from a large number of gages. Construction of the test began in December 1984 and the test has been in operation since that time; gage data in this report cover the period from December 1984 through November 1990.

Nuclear power plants have experienced actuations of fire protection systems (FPSs) under conditions for which these systems were not intended to actuate and also have experienced advertent actuations with the presence of a fire. These actuations have often damaged safety-related equipment. A review of the impact of past occurrences of both types of such events and their impact on plant safety systems, an analysis of the risk impacts of such events on nuclear power plant safety, and a cost-benefit analysis of potential corrective measures have been performed. Thirteen different scenarios leading to actuation of fire protection systems due to a variety of causes were identified. These scenarios ranged from inadvertent actuation caused by human error to hardware failure, and include seismic root causes and seismic/fire interactions. A quantification of these thirteen root causes, where applicable, was performed on generically applicable scenarios. This document, Volume 2, contains appendices A,B, and C of this report.

Nuclear power plants have experienced actuations of fire protection systems (FPSs) under conditions for which these systems were not intended to actuate and also have experienced advertent actuations with the presence of a fire. These actuations have often damaged nearby plant equipment. A review of the impact of past occurrences of both types of such events, a quantification of the risk of FPS actuation, a sensitivity study of the quantification of the risk of FPS actuation and risk calculations in terms of person-REM have been performed. Thirteen different scenarios leading to actuation of fire protection systems due to a variety of causes were identified. A quantification of these thirteen scenarios, where applicable, was performed on a 3-loop Westinghouse Pressurized water Reactor (PWR). These scenarios ranged from inadvertent actuation caused by human error to hardware failures, and include seismic root causes and seismic/fire interaction. This report estimates the contribution of FPS actuations to core damage frequency and risk.

The VICTORIA model of radionuclide behavior in the reactor coolant system (RCS) of a light water reactor during a severe accident is described. It has been developed by the USNRC to define the radionuclide phenomena and processes that must be considered in systems-level models used for integrated analyses of severe accident source terms. The VICTORIA code, based upon this model, predicts fission product release from the fuel, chemical reactions involving fission products, vapor and aerosol behavior, and fission product decay heating. Also included is a detailed description of how the model is implemented in VICTORIA, the numerical algorithms used, and the correlations and thermochemical data necessary for determining a solution. A description of the code structure, input and output, and a sample problem are provided.

Brine inflow to the Waste Isolation Pilot Plant is important in assessing the performance of the repository, and a mechanistic model is needed for performance calculations. Brine inflow experiments are being conducted, and formation parameters such as the permeability and diffusivity are inferred from these data using a simplified one-dimensional radial, uniform property, single-phase Darcy flow model. This model has met with limited success in interpreting some of the recent data. Much of the data could not be satisfactorily fit with the above model because the brine inflow rate increases with time, so a more mechanistic model is being developed based on the TOUGH and TOUGH2 computer codes. These codes are much more complex than the simplified model and include a number of parameters that have not been measured. Therefore, a one-dimensional brine inflow sensitivity study has been undertaken to evaluate the importance of a number of these parameters in influencing the behavior of brine inflow to open boreholes. In addition, two-phase conditions have been included in the study, and the sensitivity of gas inflow rates and the formation pressure and saturation distributions after 1 year are examined. These results should be helpful in determining what additional measurements are necessary to assist in the development of a more mechanistic brine inflow model.

The Precision Linear Shaped Charge (PLSC) design concept involves the independent fabrication and assembly of the liner (wedge of PLSC), the tamper/confinement, and explosive. The liner is the most important part of an LSC and should be fabricated by a more quality controlled, precise process than the tamper material. Also, this concept allows the liner material to be different from the tamper material. The explosive can be loaded between the liner and tamper as the last step in the assembly process rather than the first step as in conventional LSC designs. PLSC designs are shown to produce increased jet penetrations in given targets, more reproducible jet penetration, and more efficient explosive cross sections using a minimum amount of explosive. The Linear Explosive Shaped Charge Analysis (LESCA) code developed at SandiaNational Laboratories has been used to assist in the design of PLSCs. LESCA predictions for PLSC jet penetration in aluminum targets, jet tip velocities and jet-target impact angles are compared to measured data.

Results are presented of a detailed survey of the present state of scientific understanding of cloud electrification processes and lightning warning technology. A review is given of the principles of operation and demonstrated performance factors of lightning strike location technologies and associated commercial products. Emphasis is given to the local lightning warning problem, which is divided into two categories: detection and tracking of active storms that originate outside of and move into the declared safety zone, and early detection of cloud electrification that initiates within the zone. A prototype single-station warning system design is presented that is intended to accumulate data simultaneously from a complement of different types of sensors during intervals immediately preceding the onset of lightning conditions within the area of coverage. The resultant data base will be analyzed statistically to identify the most promising combinations of early warning indicators and to quantify their reliability as a function of the warning intervals they provide.

Multiple sources of variation will often affect the stability of a manufacturing process. Items from different batches may vary because of variation both within a batch and among different batches. Potential sources of variation include within run, run-to-run and week-to-week differences in a manufacturing process. If multiple sources of variation are present, traditional control chart methods may not be appropriate. In this report we develop control charts for monitoring these sources of variation as well as the process average. An example of how to use the control charts is given, using Field 89 data from functional testing of the MC3854 neutron tube.

GROPE is a program that examines the input to a finite element analysis (which is in the GENESIS database format) or the output from an analysis (in the EXODUS database format). GROPE allows the user to examine any value in the database. The display can be directed to the user`s terminal or to a print file.

A Quality Management System was defined by Sub-Process teams within Data Analysis Department 2722. Each of the processes is concerned with a different phase of work for intemal customers (members of the Department) and for external customers (Sandians external to the Department, or agencies outside of Sandia). This report identifies and defines the crucial Work Processes of the Department, where each Process is documented in a separate ``Chapter.`` This report documents the effort of the Data Analysis Department to effectively provide services to its customers and to assess/improve these services. Thus this report is intended to be a ``living document`` for the Department and each member of the Department is expected to follow its guidelines.

Solar heat gain inside a radiation-shielded forklift operator compartment can be a significant problem due to the ``greenhouse effect``. Battery power prohibits the use of a refrigerant type of air-conditioning system, which limits the interior temperature to be approximately equal to the outside ambient temperature through alternative cooling methods. A heat transfer analysis is performed to determine the amount of solar heat gain in this type of mobile vehicle shelter. Various results are presented that depend on exterior surface finish and temperature difference between inside and outside ambient. An amount of forced air flow along with several design recommendations are then specified to rid the compartment of this excess heat.

Sandia National Laboratories operates the Primary Standards Laboratory for the Department of Energy, Albuquerque Operations Office (DOE/AL). This report summarizes metrology activities that received emphasis in the first half of 1992 and provides information pertinent to the operation of the DOE/AL system wide Standards and Calibration Program.

Aprepro is an algebraic preprocessor that reads a file containing both general text and algebraic, string, or conditional expressions. It interprets the expressions and outputs them to the output file along with the general text. The syntax used in Aprepro is such that all expressions between the delimiters and are evaluated and all other text is simply echoed to the output file. Aprepro contains several mathematical functions, string functions, and flow control constructs. In addition, functions are included that, with some additional files, implement a units conversion system and a material database lookup system. Aprepro was written primarily to simplify the preparation of parameterized input files for finite element analyses at Sandia National Laboratories; however, it can process any text file that does not use the characters.

Calculations of residual stresses in braze joints are required to validate designs for a variety of metal/ceramic joining applications. In particular, finite element analysis (FEA) codes have the capability of incorporating either elastic-plastic or minimum creep rate constitutive models for the braze material. This paper presents both elevated temperature mechanical properties correlations for the eutectic Ag-Cu alloy, along with FEA results which use this data in calculating residual stresses in a generic metal/ceramic ``shear'' type braze joint. Three constitutive relations have been developed for eutectic Ag-Cu alloy: (i) an elastic/plastic correlation incorporating temperature-dependent yield stress and work hardening data, (ii) a high temperature minimum creep rate correlation with a temperature-dependent stress exponent and (iii) a minimum creep rate correlation using the Garofalo hyperbolic sine (sinh) equation. FEA calculations are presented for a eutectic Ag-Cu braze joint between metallized alumina ceramic and either Fe-29Ni-17Co or Fe-27Ni-25Co alloys using the three different constitutive relations for the brazement. The two creep correlations, since they are time-dependent, permit a study of the effect of various cooldown cycles on the maximum residual stress in the alumina ceramic. For the cooldown profiles studied in this paper, lower residual stresses are predicted in the ceramic-relative to the elastic-plastic model - when either of the two creep models are used as the constitutive law for the eutectic Ag-Cu braze joint. A second important result is that the simulations which incorporate the Fe-29-Ni-17Co alloy show higher peak stresses than the Fe-27Ni-25Co alloy at 420°C, along with much lower peak stresses compared to Fe-27Ni-25Co alloy at room temperature. The reason for this somewhat surprising behavior can be understood in terms of the coefficient of thermal expansion for the two Fe-Ni-Co alloys.

GJOIN is a two- or three-dimensional mesh combination program. GJOIN combines two or more meshes written in the GENESIS mesh database format into a single GENESIS mesh. Selected nodes in the two meshes that are closer than a specified distance can be combined The geometry of the mesh databases can be modified by scaling, offsetting, revolving, and mirroring. The combined meshes can be further modified by deleting, renaming, or combining material blocks, sideset identifications, or nodeset identifications. GJOIN is one of the mesh generation tools in the Sandia National Laboratories Engineering Analysis Code Access System (SEACAS). GJOIN is typically used with the other SEACAS mesh generation codes GEN3D, GENSHELL, GREPOS, and Aprepro.

A description of ion-irradiation-induced reduction in the photoluminescence (PL) signal from porous silicon is given and a simple model which is consistent with a nanocrystalline Si structure is presented. Ion irradiation with 250 keV Ne is used to controllably reduce the integrated PL signal by 20% after a fluence of 4*1012 Ne cm-2 and completely eliminate the PL signal after a fluence of 4*1013 Ne cm-2. The use of vacuum and air annealing to recover ion-induced damage is also described, but the high temperatures for annealing cause elimination of the PL signal.

Pyro shock loads are generated in many missile or rocket systems when stages are separated or shrouds are removed. These shocks are localized, of short rise time (10's of ns) and of very high stress level. This paper will document some anomalous behavior that occurs when pyro shock accelerometers (Endevco 7270A) are exposed to levels of high frequency shock that is higher than the manufacturer's recommended limits. Such shocks occur in many pyro shock events. Standard, accepted recording techniques can produce totally erroneous data with no obvious indicator that the data is in error. Wide band data recording, along with Fourier Analysis of the data, and dynamic analysis, made by the gage manufacturer of the transducer, allow recognition of some of the non-standard response modes excited but no method of quantifying the corrupted data has been developed. Wide band recording, which will preserve the data in the gage resonance range and above, are required to insure understanding of these pyro shock events.

We have measured the efficiency (tracks per incident neutron) of pure CR-39 for detecting DD and DT neutrons. Neutrons having average energies of 2.9 MeV (DD) and 14.8 MeV (DT) were produced by a 200-keV electrostatic accelerator and the neutron yields were measured using the associated particle counting technique. All CR-39 samples irradiated by DD or DT neutrons were etched for 2 h in a 70°, 6.25-N- NaOH bath. For bare CR-39, the efficiencies for detecting 2.9- and 14.8-MeV neutrons were found to be (1.3±0.4)×10 -4 and (5.0±1.8)×10-5, respectively. We also investigated using CR-39 and polyimide as proton radiators. For detecting 2.9-MeV neutrons, the radiators had no significant effect on efficiency; but for detecting 14.8-MeV neutrons the polyimide radiator increased the efficiency to (7.8±2.8)×10-5.

This report describes preliminary probabilistic sensitivity analyses of long term gas and brine migration at the Waste Isolation Pilot Plant (WIPP). Because gas and brine are potential transport media for organic compounds and heavy metals, understanding two-phase flow in the repository and the surrounding Salado Formation is essential to evaluating long-term compliance with 40 CFR 268.6, which is the portion of the Land Disposal Restrictions of the Hazardous and Solid Waste Amendments to the Resource Conservation and Recovery Act that states the conditions for disposal of specified hazardous wastes. Calculations described here are designed to provide guidance to the WIPP Project by identifying important parameters and helping to recognize processes not yet modeled that may affect compliance. Based on these analyses, performance is sensitive to shaft-seal permeabilities, parameters affecting gas generation, and the conceptual model used for the disturbed rock zone surrounding the excavation. Brine migration is less likely to affect compliance with 40 CFR 268.6 than gas migration. However, results are preliminary, and additional iterations of uncertainty and sensitivity analyses will be required to provide the confidence needed for a defensible compliance evaluation. Specifically, subsequent analyses will explicitly include effects of salt creep and, when conceptual and computational models are available, pressure-dependent fracturing of anhydrite marker beds.

Iterative, annual performance-assessment calculations are being performed for the Waste Isolation Pilot Plant (WIPP), which is a planned underground repository in southeastern New Mexico for the disposal of transuranic radioactive waste. The performance-assessment calculations estimate long-term (10,000-year) radionuclide releases from the disposal system to the accessible environment. The estimation of the releases is probabilistic in nature, requiring system parameters to be described with probability distributions. Because direct experimental data in some areas are presently insufficient or unavailable to form the required distributions, researchers at Sandia National Laboratories have used a formalized expert-judgment elicitation procedure to determine the state of knowledge in these areas. Expert judgment was used to estimate the concentrations of specific radionuclides in a repository brine that might be forced up an intruding borehole, and also to estimate the distribution coefficients to determine the retardation of radionuclides in the overlying Culebra Dolomite. The variables representing these concentrations and coefficients have been shown by 1990 sensitivity analyses to be among the set of parameters making the greatest contribution to the uncertainty in WIPP performance assessment predictions. Using available information, the experts (one expert panel addressed concentrations and a second panel addressed retardation) were briefed on the problem of insufficient experimental data and were formally elicited to obtain probability distributions that characterize the uncertainty in fixed, but unknown, quantities. The probability distributions developed by the experts were incorporated into the 1991 and 1992 performance-assessment calculations.

Progress in Z-pinch experiments at Sandia's Saturn facility have underscored a need for an absolute yield measurement for DD fusion neutrons. The technique chosen for making this absolute yield measurement was neutron activation of indium metal samples. To calibrate the technique, a 175-keV deuteron beam was allowed to impinge on a 3.0-μm-thick erbium deuteride target, producing neutrons through the 2H(d,n)3He fusion reaction. The neutron flux produced at 0° and incident on nominal 5-g indium samples was determined by the associated particle method. This method employed protons measured from the 2H(d,p)3H reaction to infer the neutron flux produced. After neutron irradiation, the activity of the indium samples was measured with a Ge gamma-ray detector. The total activity of the metastable state 115mIn (336.23 keV) was measured, compared with the total incident flux, and a calibration factor (indium counts/neutron/gram of indium) determined. For completeness, a calibration factor for DT neutrons from the 3H(d,n)4He fusion reaction was also obtained through the measured activity of the metastable state 114mIn(190.29 keV). The experiment and the measured calibration factors for both reactions are described in the paper.

The CR-39/range-filter technique measures ion energy by determining the maximum filter thickness which ions can penetrate. CR-39 located behind the filter records the ions. This method is used to measure peak voltage in pulsed power accelerators. We investigated range and straggling effects in this diagnostic by exposing it to 8- and 15-MeV protons for both Al and Ta filters. The range agreed with published values to better than ±6%. The range straggling decreased for higher incident ion energy and lower atomic number, as expected, although there were differences up to a factor of 1.7 between the experimental values and predictions. The dependence of the track diameter distribution on ion energy enabled us to establish a signature which is characteristic of ions which penetrate a filter, via straggling. These results can be used to evaluate the errors present when this diagnostic is used to measure accelerator voltage.

In recent proton beam experiments on PBFA-II, foam-filled gold targets and gas-filled spherical exploding pushers were shot as physics targets. Surrounding these targets were gold foils used to characterize the beam. The target fabrication and characterization are presented in this paper.

Because a direct measurement of the voltage (V) in pulsed power bremsstrahlung sources can be difficult, the energy spectrum of x rays emitted is sometimes used to infer V. Both the voltage and current in such sources vary with time. Moreover, for modern x-ray simulators with multiple cathodes, multiple voltages may exist simultaneously. We demonstrate here how such sources lead to systematic errors in several types of simple-to-field x-ray voltage measurements, especially those with broad spectral response functions, when calibrated against constant-potential bremsstrahlung spectra.

The laser-initiated LEVIS source is intended to provide an active source in the PBFA II ion diode by generation of a preformed lithium anode plasma. Visible spectra recorded with a streaked spectrograph are used to help evaluate the source performance. The absence of Stark shifting of the Li I 2p-3d and 2s-2p light confirms that a plasma is created over the anode surface. At lower LEVIS laser intensities this plasma erodes back toward the anode as the ion beam current grows. Considerable improvements in anode plasma purity have been noted when the anode is heated for several hours. The LEVIS source microdivergence estimated from the carbon ion transverse energy is less than 14 mrad, meeting the near term requirements for PBFA II target experiments. © 1992 National Technical Information Service.

Helium removal experiments were conducted in TEXTOR with a small helium self-pumping module located in a modified ALT-I limiter head. The module contained two heated nickel alloy trapping plates, a nickel deposition filament array, a Langmuir probe, flux probe, and thermocouples. The experiment examined plasma helium removal via trapping of helium ions in the deposited nickel surfaces. Such helium removal was successfully observed, with about 10% of the helium in a 10% He/D plasma being removed in a ∼1 s period. The module was found to be compatible with overall tokamak operation with essentially no sputtered nickel entering the core plasma. The temperature rise on the ion-exposed inner trapping plate, during a plasma shot, is consistent with a local sheath potential of ∼3kTe. Post-tokamak test examination of the trapping plates shows helium atom concentrations in the deposited nickel consistent with the observed helium removal, and shows very small D concentrations. © 1992 Elsevier Science Publishers B.V. All rights reserved.

We present results from initial experiments with a high impedance applied-B extraction diode on the SABRE ten stage linear induction accelerator (6 MV, 300 kA). We have demonstrated efficient coupling of power from the accelerator through an extended MTTL (Magnetically Insulated Transmission Line) into a high intensity ion beam. Both MITL electron flow in the diode region and ion diode behavior, including ion source turn-on, virtual cathode formation and evolution, enhancement delay, and ion coupling efficiency, are strongly influenced by the geometry of the diode insulating magnetic field. For our present diode electrode geometry, electrons from the cathode feed play a large role in the evolution of the virtual cathode. Both experimental data and particle-in-cell numerical simulations show that a uniform radial distribution of these feed electrons is required for uniform ion emission and efficient diode operation. © 1992 National Technical Information Service.

An active ion source, LEVIS (Laser Evaporation Ion Source), using a short pulsed Nd laser (1.06 m, 8ns) to form a thin Li vapor layer and a tuned dye laser (670.8nm, μsec) for ionization is being developed at Sandia. The LEVIS process has been developed and characterized in the laboratory. Initial experiments using these ion sources on PBFA-II produced ion beams with a low fraction of lithium ions and with low voltages. Recent experiments using improved distribution optics and anode cleaning techniques are described. © 1992 National Technical Information Service.

Significant progress in the generation and focusing of ion beams generated by PBFA-II has enabled us to begin experiments in ion beam coupling and target physics. Data from these experiments indicates that we can reproducibly deliver 50 KJ of 5 MeV protons at an average power intensity of 3.5 TW/cm 2 to a 6 mm diameter by 6 mm tall cylindrical target. The implosion of spherical exploding pusher targets and the radiation production from foam-filled cylindrical thermal targets were studied in these experiments. They demonstrated that high quality target data can be obtained on PBFA-II. Specific deposition rates of about 100 TW/g were achieved in these experiments. This deposition rate marks the boundary between the regime where enhanced ion deposition and equation-of-state (EOS) physics are studied (10-100 TW/g) and the regime where radiation-conversion and radiation-transport physics are studied (100-1000 TW/g). Experiments in the radiation-conversion regime are now of primary importance in our program because these experiments will test the target physics basis for ion-driven ICE Experiments using a thin film LiF source have produced an intensity of 1 TW/cm 2 of lithium ions. This beam has a potential specific deposition rate of 300-400 TW/g in hydrocarbon foams. However, radiation conversion experiments will require an increased total energy content of this beam in order to overcome the specific internal energy of the foam. Further increases in ion beam intensity and energy content are being pursued in a multi-pronged attack. Understanding and controlling ion beam divergence is the highest program priority. Present understanding indicates that instabilities in the electron sheath cause significant ion beam divergence. Our understanding suggests that this contribution to the ion divergence can be decreased by operating the diode at a low enhancement through the use of high applied magnetic fields or by modifying the electron distribution near the anode via electron limiters. The new 9 cm radius Compact Diode has the capability of generating 8 T applied magnetic fields which will enable divergence experiments in the low-enhancement, high-B regime. Experiments with the LEVIS (Laser Evaporation Ion Source) lithium source have demonstrated the existence of a preformed plasma, as determined by visible-emission spectroscopy of the anode plasma. Work on improving lithium purity with this source is in progress. This active anode plasma will be used in experiments testing the effectiveness of electron limiters in controlling ion beam divergence. We are also working to understand the interrelation between accelerator coupling, diode physics, and ion beam focusing in order to optimize the diode configuration to maximize the power intensity on target. Success in these experiments will provide an adequate lithium beam for performing target experiments exploring radiation conversion and radiation transport physics in ion-driven ICF. © 1992 National Technical Information Service.

We have built a five-channel, x-ray detector array based on diamond photoconducting detectors (PCDs). The diamond elements have dimensions of 3 mm × 1 mm × 1 mm (or 0.5 mm). We use diamond PCDs for their stability, flat spectral response, and low leakage currents. The good time response of diamond PCDs is due to the 100-ps electron/hole recombination time. Filters were designed to give information in the 1-10-keV spectral region. Calibration of the diamond PCDs showed sensitivities between 4 and 7 × 10-4 A/W for a bias of 100 V. We shall present data from z-pinch experiments on Saturn.

Using concepts of decision analysis, this paper examines how government policy makers might consider and evaluate the contribution of additional inspection, openness, and confidence-building measures to diplomatic questions involving compliance with arms control agreements. During the current debate among parties to the Biological Weapons Convention as to what constitutes effective verification of compliance with that Convention, these analytical concepts were employed to evaluate some proposed inspection or confidence-building measures. Some of the salient points not bound up in the confidentiality of on-going negotiations will be summarized here.