Publications

Inside this issue is a farewell to Testing Technology message from technical advisor, Ruth David. Also included are articles on: Testing the I-40 bridge over the Rio Grande, simulated reactor meltdown studies, an inexpensive monitor for testing integrated circuits, testing of antihelicoptor mines, and quality assurance on aircraft inspection.

This report describes the HP370 component of the Enhanced Graphics System (EGS) used at Tonopah Test Range (TTR). Selected Radar data is fed into the computer systems and the resulting tracking symbols are displayed on high-resolution video monitors in real time. These tracking symbols overlay background maps and are used for monitoring/controlling various flight vehicles. This report discusses both the operational aspects and the internal configuration of the HP370 Workstation portion of the EGS system.

An extensive set of direct-strike lightning tests has been carried out on a set of facsimile assembly joints of the kinds employed in the design of nuclear weapon cases. Taken as a whole, the test hardware included all the conceptual design elements that are embodied, either singly or in combination, in any specific assembly joint incorporated into any stockpiled weapon. During the present testing, the effects of all key design parameters on the voltages developed across the interior of the joints were investigated under a range of lightning stroke current parameter values. Design parameter variations included the types and number of joint fasteners, mechanical preload, surface finish tolerance and coatings, and the material from which the joint assembly was fabricated. Variations of the simulated lightning stroke current included amplitude (30-, 100-, and 200-kA peak), rise time, and decay time. The maximum voltage observed on any of the test joints that incorporated proper metal-to-metal surface contact was 65 V. Typical response values were more on the order of 20 V. In order to assess the effect of the presence of a dielectric coating (either intentional or as a result of corrosion) between the mating surfaces of a joint, a special configuration was tested in which the mating parts of the test assembly were coated with a 1-mil-thick dielectric anodizing layer. First strokes to these test assemblies resulted in very narrow voltage spikes of amplitudes up to 900 V. The durations of these spikes were less than 0.1 {mu}s. However, beyond these initial spikes, the voltages typically had amplitudes of up to 400 V for durations of 3 to 5 {mu}s.

A limited pilot production run on PESC silicon solar cells for use at high concentrations (200 to 400 suns) is summarized. The front contact design of the cells was modified for operation without prismatic covers. The original objective of the contract was to systematically complete a process consolidation phase, in which all the, process improvements developed during the contract would be combined in a pilot production run. This pilot run was going to provide, a basis for estimating cell costs when produced at high throughput. Because of DOE funding limitations, the Photovoltaic Concentrator Initiative is on hold, and Applied Solar`s contract was operated at a low level of effort for most of 1993. The results obtained from the reduced scope pilot run showed the effects of discontinuous process optimization and characterization. However, the run provided valuable insight into the technical areas that can be optimized to achieve the original goals of the contract.

The use of glasses is widespread in making hermetic, insulating seals for many electronic components. Flat panel displays and fiber optic connectors are other products utilizing glass as a structural element. When glass is cooled from sealing temperatures, residual stresses are generated due to mismatches in thermal shrinkage created by the dissimilar material properties of the adjoining materials. Because glass is such a brittle material at room temperature, tensile residual stresses must be kept small to ensure durability and avoid cracking. Although production designs and the required manufacturing process development can be deduced empirically, this is an expensive and time consuming process that does not necessarily lead to an optimal design. Agile manufacturing demands that analyses be used to reduce development costs and schedules by providing insight and guiding the design process through the development cycle. To make these gains, however, viscoelastic models of glass must be available along with the right tool to use them. A viscoelastic model of glass can be used to simulate the stress and volume relaxation that occurs at elevated temperatures as the molecular structure of the glass seeks to equilibrate to the state of the supercooled liquid. The substance of the numerical treatment needed to support the implementation of the model in a 3-D finite element program is presented herein. An accurate second-order, central difference integrator is proposed for the constitutive equations, and numerical solutions are compared to those obtained with other integrators. Inherent convergence problems are reviewed and fixes are described. The resulting algorithms are generally applicable to the broad class of viscoelastic material models. First-order error estimates are used as a basis for developing a scheme for automatic time step controls, and several demonstration problems are presented to illustrate the performance of the methodology.

The necessity to evaluate our participant Quality Assurance (QA) Program for the Yucca Mountain Site Characterization Project (YMP) against the Office of Civilian Radioactive Waste Management (OCRWM) Quality Assurance Requirements and Description (QARD) issued December 1992, presented an opportunity to improve the QA Program. For some time, the SNL YMP technical staff had complained that the QA requirements imposed on their work were cumbersome and inhibited their ability to perform investigations using scientific methods. There was some truth to this, since SNL had over the years developed some procedures with many detailed controls that were far beyond what was required by project QA requirements. This had occurred either as a result of responding to numerous audit findings with a ``make the auditor happy`` attitude or with an attempt to cover every contingency. Procedures affecting scientific work were authored by the technical staff in an effort to provide them with ownership of the process; unfortunately, there were problems. Procedures were inconsistent because of the varied writing styles and differing perceptions of the degree of QA controls required to implement the program. It was extremely difficult to get all of the technical staff to accept the QA program as it was intended. These issues were endemic to the program and resulted in the QARD, the actual requirements, being written by a team of QA professionals. Once new QARD requirements were issued, an opportunity to evaluate the QA Program and to revise it not only to meet the QARD, but also to make it more plausible and meaningful to the technical staff, was presented. The discussion that follows will describe how the program was changed, will present both the positive and negative experiences observed by SNL personnel during the QARD transition, and will provide some recommendations.

One source of uncertainty in calculating radionuclide releases from a potential radioactive-waste at Yucca Mountain, Nevada, is uncertainty in the unsaturated-zone stratigraphy. Uncertainty stratigraphy results from sparse drillhole data; possible variations in stratigraphy are modeled using the geostatistical method of indicator simulation. One-dimensional stratigraphic columns are generated and used for calculations of groundwater flow and radionuclide transport. There are indications of a dependence of release on hydrogeologic-unit thicknesses, but the resulting variation in release is smaller than variations produced by other sources of uncertainty.

The evaluation of the stability of the openings for the Exploratory Studies Facility and a potential repository for high-level nuclear waste at Yucca Mountain, Nevada will require computer codes capable of predicting slip on rock joints resulting from changes in thermal stresses. The geometrical method of analysis of moire fringe analysis was used to evaluate the magnitude and extent of frictional sliding in a layered polycarbonate rock mass model containing a circular hole. Slips were observed in confined zones around the hole and micron resolutions were obtained. Unpredicted and uncontrolled uniform slip of several interfaces in the model were observed giving considerable uncertainty in the boundary conditions of the model, perhaps making detailed comparison with numerical models impossible.

Prediction of the deformation behavior of large engineering structures in jointed rock under a specified loading history requires the extensive use of numerical simulation. For example, the evaluation of the stability of the openings for the Exploratory Studies Facility and a potential repository for high-level nuclear waste at Yucca Mountain, Nevada will require computer codes capable of predicting slip on rock joints resulting from changes in thermal stresses. The testing and ultimate validation of these complex finite element computer codes is an important step in their development before their use as a design tool for an engineering structure or for the study of some other practical problem. While field tests may be ultimately necessary, the authors propose a different and more thorough approach where early tests are done on a bench scale with easily characterized materials and geometries. For these bench-scale tests, the basic approach is to construct a laboratory specimen with a known geometry from an easily characterized material. Digital video imaging combined with the geometric moire fringe method of strain analysis is used to measure and derive the displacements on the sample under load. Here the authors present the method of acquiring and analyzing the moire data and give an analysis of its problems and benefits.

To build a bridge with customers, we balance the linear modeling process with the dynamics of the individuals we serve, who may feel unfamiliar, even confused, with that process. While it is recognized that human factors engineers improve the physical aspect of the workplace, they also work to integrate customers` cognitive styles, feelings, and concerns into the workplace tools. We take customers` feelings into consideration and integrate their expressed needs and concerns into the modeling sessions. After establishing an agreeable, professional relationship, we use a simple, portable CASE tool to reveal the effectiveness of NIAM. This tool, Modeler`s Assistant, is friendly enough to use directly with people who know nothing of NIAM, yet it captures all the information necessary to create complete models. The Modeler`s Assistant succeeds because it organizes the detailed information in an enhanced text format for customer validation. Customer cooperation results from our modeling sessions as they grow comfortable and become enthused about providing information.

Verification measurements may be used to help ensure nuclear criticality safety when burnup credit is applied to spent fuel transport and storage systems. The FORK system measures the passive neutron and gamma-ray emission from spent fuel assemblies while in the storage pool. It was designed at Los Alamos National Laboratory for the International Atomic Energy Agency safeguards program and is well suited to verify burnup and cooling time records at commercial Pressurized Water Reactor (PWR) sites. This report deals with the application of the FORK system to burnup credit operations.

We present two algorithms that use membership and equivalence queries to exactly identify the concepts given by the union of s discretized axis-parallel boxes in d-dimensional discretized Euclidean space where there are n discrete values that each coordinate can have. The first algorithm receives at most sd counterexamples and uses time and membership queries polynomial in s and log n for d any constant. Further, all equivalence queries made can be formulated as the union of O(sd logs) axis-parallel boxes. Next, we introduce a new complexity measure that better captures the complexity of a union of boxes than simply the number of boxes and dimensions. Our new measure, u, is the number of segments in the target polyhedron where a segment is a maximum portion of one of the sides of the polyhedron that lies entirely inside or entirely outside each of the other halfspaces defining the polyhedron. We then present an improvement of our first algorithm that uses time and queries polynomial in u and log n. The hypothesis class used here is decision trees of height at most 2sd, Further we can show that the time and queries used by this algorithm are polynomial in d and log n for s any constant thus generalizing the exact learnability of DNF formulas with a constant number of terms. In fact, this single algorithm is efficient for either s or d constant.

This presentation (consisting of vugraphs) first provides the background motivation for Sandia`s effort for the development of improved crystalline silicon solar cells. It then discusses specific results and progress, and concludes with a brief discussion of options for next year.

This report describes the equipment required for initial assembly/maintenance and inspection/resetting of the Fifth Wheel system. It also gives a step-by-step procedure for initial assembly/maintenance inspection and procedures for resetting the system and Eager-Pac installation. The Fifth Wheel system is associated with a tractor-type vehicle used for materials handling.

High Consequence System Surety is an ongoing project at Sandia National Laboratories. This project pulls together a multi- disciplinary team to integrate the elements of surety into an encompassing process. The surety process will be augmented and validated by applying it to an automated system handling a critical nuclear weapon component at the Mason & Hanger Pantex Plant. This paper presents the development to date of an integrated, high consequence surety process.

Heavy Ion Backscattering Spectrometry (HIBS) is a new ion beam analysis tool using heavy, low-energy ions in backscattering mode which can detect very low levels of surface contamination. By taking advantage of the greatly increased scattering cross-section for such ion beams and eliminating unwanted substrate scattering with a thin carbon foil, our research system has achieved a sensitivity ranging from {approximately}5{times}10{sup 10} atoms/cm{sup 2} for Fe to {approximately}1{times}10{sup 9} atoms/cm{sup 2} for Au on Si, without preconcentration. A stand-alone HIBS prototype now under construction in collaboration with SEMATECH is expected to achieve detection limits of {approximately}5{times}10{sup 9} atoms/cm{sup 2} for Fe and {approximately}1{times}10{sup 8} atoms/cm{sup 2} for Au on Si, again without preconcentration. Since HIBS is standardless and has no matrix effects, it will be useful not only as a standalone tool, but also for benchmarking standards for other tools. This conference is testimony to the importance of controlling contamination in microelectronics manufacturing. By the turn of the century, very large scale integrated circuit processing is expected to require contamination levels well below 1{times}10{sup 9} atoms/cm{sup 2} in both starting materials and introduced by processing. One of the most sensitive of existing general-purpose tools is Total reflection X-Ray Fluorescence (TXRF), which can detect {approximately}1{times}10{sup 10} atoms/cm{sup 2} levels of some elements such as Fe and Cu, but for many elements it is limited to 1{times}10{sup 12} atoms/cm{sup 2} or worse. TXRF can achieve a sensitivity of 10{sup 8} atoms/cm{sup 2} through the use of synchrotron radiation or via pre-concentration using Vapor Phase Decomposition. HIBS provides an ion beam analysis capability with the potential for providing similar sensitivity at medium Z and higher sensitivity at larger Z, all without pre-concentration or matrix effects.

We report the results of to separate long-term tests of batteries and charge controllers in small stand-alone PV systems. In these experiments, seven complete systems were tested for two years at each of two locations: Sandia National Laboratories in Albuquerque and the Florida Solar Energy Center in Cape Canaveral, Florida. Each system contained a PV array, flooded-lead-acid battery, a charge controller and a resistive load. Performance of the systems was strongly influenced by the difference in solar irradiance at the two sites, with some batteries at Sandia exceeding manufacturer`s predictions for cycle life. System performance was strongly correlated with regulation reconnect voltage (R{sup 2} correlation coefficient = 0.95) but only weakly correlated with regulation voltage. We will also discuss details of system performance, battery lifetime and battery water consumption.

A model is presented which describes the formation of surface damage ``gouging`` on the rails that guide rocket sleds. An unbalanced sled can randomly cause a very shallow-angle, oblique impact between the sled shoe and the rail. This damage phenomenon has also been observed in high-velocity guns where the projectile is analogous to the moving sled shoe and the gun barrel is analogous to the stationary rail. At sufficiently high velocity, the oblique impact will produce a thin hot layer of soft material on the contact surfaces. Under the action of a normal moving load, the soft layer lends itself to an anti-symmetric deformation and the formation of a ``hump`` in front of the moving load. A gouge is formed when this hump is overrun by the sled shoe. The phenomenon is simulated numerically using the CTH strong shock physics code, and the results are in good agreement with experimental observation.

The objective of this paper is to provide a general overview of hydrologic conditions at the Waste Isolation Pilot Plant (WIPP) by describing several key hydrologic studies that have been carried out as part of the site characterization program over the last 20 years. The paper is composed of three parts: background information about general objectives of the WIPP project; information about the geologic and hydrologic setting of the facility; and information about three aspects of the hydrologic system that are important to understanding the long-term performance of the WIPP facility. For additional detailed information, the reader is referred to the references cited in the text.

Cast blasting can be designed to utilize explosive energy effectively and economically for coal mining operations to remove overburden material. The more overburden removed by explosives, the less blasted material there is left to be transported with mechanical equipment, such as draglines and trucks. In order to optimize the percentage of rock that is cast, a higher powder factor than normal is required plus an initiation technique designed to produce a much greater degree of horizontal muck movement. This paper compares two blast models known as DMC (Distinct Motion Code) and SABREX (Scientific Approach to Breaking Rock with Explosives). DMC, applies discrete spherical elements interacted with the flow of explosive gases and the explicit time integration to track particle motion resulting from a blast. The input to this model includes multi-layer rock properties, and both loading geometry and explosives equation-of-state parameters. It enables the user to have a wide range of control over drill pattern and explosive loading design parameters. SABREX assumes that heave process is controlled by the explosive gases which determines the velocity and time of initial movement of blocks within the burden, and then tracks the motion of the blocks until they come to a rest. In order to reduce computing time, the in-flight collisions of blocks are not considered and the motion of the first row is made to limit the motion of subsequent rows. Although modelling a blast is a complex task, the DMC can perform a blast simulation in 0.5 hours on the SUN SPARCstation 10--41 while the new SABREX 3.5 produces results of a cast blast in ten seconds on a 486-PC computer. Predicted percentage of cast and face velocities from both computer codes compare well with the measured results from a full scale cast blast.

The Mixed Waste Landfill Integrated Demonstration (MWLID) focuses on ``in-situ`` characterization, monitoring, remediation, and containment of landfills in and environments that contain hazardous and mixed waste. The MWLID mission is to assess, demonstrate, and transfer technologies and systems that lead to faster, better, cheaper, and safer cleanup. Most important, the demonstrated technologies will be evaluated against the baseline of conventional technologies. Key goals of the MWLID are routine use of these technologies by Environmental Restoration Groups throughout the DOE complex and commercialization of these technologies to the private sector. The MWLID is demonstrating technologies at hazardous waste landfills located at Sandia National Laboratories and on Kirtland Air Force Base. These landfills have been selected because they are representative of many sites throughout the Southwest and in other and climates.

This paper addresses the issues surrounding the use of NIAM to capture time dependencies in a domain of discourse. The NIAM concepts that support capturing time dependencies are in the event and process portions of the NIAM metamodel, which are the portions most poorly supported by a well-established methodology. This lack of methodological support is a potentially serious handicap in any attempt to apply NIAM to a domain of discourse in which time dependencies are a central issue. However, the capability that NIAM provides for validating and verifying the elementary facts in the domain may reduce the magnitude of the event/process-specification task to a level at which it could be effectively handled even without strong methodological support.

A statistical design of experiments approach has been employed to evaluate the particle removal efficacy of the SC-1/megasonic clean for sub-0.15 {mu}m inorganic particles. The effects of megasonic input power, solution chemistry, bath temperature, and immersion time have been investigated. Immersion time was not observed to be a statistically significant factor. The NH{sub 4}OH/H{sub 2}O{sub 2} ratio was significant, but varying the molar H{sub 2}O{sub 2} concentration had no effect on inorganic particle removal. Substantially diluted chemistries, performed with high megasonic input power and moderate-to-elevated temperatures, was shown to be very effective for small particle removal. Bath composition data show extended lifetimes can be obtained when high purity chemicals are used at moderate (eg., 45{degrees}C) temperature. Transition metal surface concentrations and surface roughness have been measured after dilute SC-1 processing and compared to metallic contamination following traditional SC-1.

I{sub DDQ} testing is mandatory to ensure that low power CMOS ICs meet their design intent. I{sub DDQ} testing is both a design verifier for low quiescent current and a sensitive production test for defects. Quiescent power reduction is particularly important for products such as cardiac pacemakers, laptop computers, and cellular telephones.

Transformers of two different designs; and unencapsulated pot core and an encapsulated toroidal core have been modeled for circuit analysis with circuit simulation tools. We selected MicroSim`s PSPICE and Anology`s SABER as the simulation tools and used experimental BH Loop and network analyzer measurements to generate the needed input data. The models are compared for accuracy and convergence using the circuit simulators. Results are presented which demonstrate the effects on circuit performance from magnetic core losses, eddy currents, and mechanical stress on the magnetic cores.