Publications

Corrosion is a leading material degradation mode observed in many military systems. This report contains a description of a small project that was performed to allow some of the important electrochemical aspects of two distinct and potentially relevant degradation modes to be better understood: environmentally assisted cracking (EAC) of aluminum alloys and corrosion in moist salt. Two specific and respective tasks were completed: (A) the characterization of the effect of aluminum microstructural variability on its susceptibility to EAC, and (B) the development of experimental and analytical techniques that can be used to identify the factors and processes that influence the corrosivity of moist salt mixtures. The resultant information constitutes part of the basis needed to ultimately predict component reliability and/or possibly to identify techniques that could be used to control corrosion in critical components. In Task A, a physical model and related understanding for the relevant degradation processes were formulated. The primary result from Task B included the identification and qualitative validation of a methodology for determining the corrosivity of salt mixtures. A detailed compilation of the results obtained from each of these two diverse tasks is presented separately in the body of this report.

This report describes the creation of three-dimensional numerical models of selected rock-matrix properties for the region of the potential high-level nuclear waste repository site at Yucca Mountain, which is located in southern Nevada. The models have been generated for a majority of the unsaturated and shallow saturated zone within an area referred to within the Yucca Mountain Site Characterization project as the site area. They comprise a number of material properties of importance both to detailed process-level modeling activities and to more summary-style performance assessment modeling. The material properties within these models are both spatially variable (heterogeneous) and spatially correlated, as the rocks are understood from data obtained from site-characterization drill holes widely scattered across the site area.

This report summarizes the investigation and evaluation of several {open_quotes}compact{close_quotes} drill rigs which could be used for drilling geothermal production wells. Use of these smaller rigs would save money by reducing mobilization costs, fuel consumption, crew sizes, and environmental impact. Advantages and disadvantages of currently-manufactured rigs are identified, and desirable characteristics for the {open_quotes}ideal{close_quotes} compact rig are defined. The report includes a detailed cost estimate of a specific rig, and an evaluation of the cost/benefit ratio of using this rig. Industry contacts for further information are given.

During the DOE Onsite Review in August 1996, Sandia`s Executive Vice President formally proposed combining Sandia`s Institutional Plan and Operating Plan, and their associated processes. The Assistant Secretary for Defense Programs subsequently approved a pilot plan to do so. This pilot plan is intended to comply with one of our new strategic objectives (see section 3.7), which entails creating an infrastructure that is a competitive advantage for our strategic missions. Therefore, Sandia`s planning organization integrated the information in the two plans and collected the data with a unified call. These data can not be combined in multiple ways, depending on customer requirements. Recently, executive management revamped Sandia`s Strategic Plan by creating eight new strategic objectives: four primary whats and four supporting hows. The new strategic objectives are set forth in chapters 3 through 5 of this document. The four primary objectives cover nuclear weapons responsibilities, nonproliferation and materials control, energy and critical infrastructures, and emerging national security threats. The major programmatic initiatives in chapter 7 are grouped accordingly. However, the programmatic descriptions in chapter 6 and the associated funding tables in chapter 9 continue to be presented by DOE Budget and Reporting Code, as in previous Sandia institutional plans. As an aid to the reader, the four primary strategic objectives in chapter 3 are cross-referenced to the program information in chapter 6.

This paper describes the method by which Sandia National Laboratories has deployed information technology to the line organizations and to the desktop as part of the integrated information services organization under the direction of the Chief Information officer. This deployment has been done by the Computer Support Unit (CSU) Department. The CSU approach is based on the principle of providing local customer service with a corporate perspective. Success required an approach that was both customer compelled at times and market or corporate focused in most cases. Above all, a complete solution was required that included a comprehensive method of technology choices and development, process development, technology implementation, and support. It is the authors hope that this information will be useful in the development of a customer-focused business strategy for information technology deployment and support. Descriptions of current status reflect the status as of May 1997.

Significant progress has been made over the past year in understanding the chemistry and processing challenges associated with {sup 99}Mo production using Cintichem type targets. Targets fabricated at Los Alamos National Laboratory have been successfully irradiated in fuel element locations at the Annular Core Research Reactor (ACRR) and processed at the Sandia Hot Cell Facility. The next goal for the project is to remove the central cavity experiment tube from the reactor core, allowing for the irradiation of up to 37 targets. After the in-core work is complete, the reactor will be capable of producing significant quantities of {sup 99}Mo.

The Monitoring Systems Technology Center (MSTC) at Sandia National Laboratories has recently upgraded its Satellite Parts Inventory Forms 3.0 application to Developer/2000 for the web. This involved changing from a character based Forms 3.0 system on an HP-UX 9000 database and forms server to a GUI forms 4.5 web- based system on Windows NT 4.0 Forms Serve. The need to migrate the MSTC Satellite Parts Inventory System to a newer supported software environment, that was easy to access and use, and was year 2000 compliant, drove the migration from forms 3.0. This paper will examine the steps of this successful migration to a web environment in detail. The MSTC Satellite Parts Inventory System includes a parts inventory application for inventory management of flight qualified electronic parts. This application tracks parts from receipt to fabrication, including manufacturer information such as lot and date, and quantities data such as lot totals, quantity on order and reorder levels. The system keeps a current count of parts that are used in kitting modules/assemblies for fabrication, does automated picks of the oldest parts, and allows suggested parts to be pulled or put back in stock and the required part pulled in place of the system suggested part. The system also flags and notifies component engineers of parts that fall below a certain level and includes traceability of parts to module record of assembly (ROA), module ROA repairs, drawings definition, CAD queue scheduling, purchase requisition records, and module action and document management.

The ability to model the packing of polymers in melts and blends is important in many polymer applications. One significant application is the development of new polymer blends. It would be exceedingly helpful to the materials chemist if molecular modeling could be employed to predict the thermodynamics and phase behavior of hypothetical polymer alloys before embarking on a time consuming and expensive synthesis program. The well known Flory-Huggins theory has been remarkably successful in describing many aspects of polymer mixing from a qualitative point of view. This theory is known, however, to suffer from several deficiencies which can be traceable to the fact that: (1) it is a lattice model requiring both monomer components to have the same volume; and (2) a mean field or random mixing approximation is made which effectively ignores chain connectivity. Because of these limitations the Flory-Huggins theory does not include packing effects and cannot be used to make quantitative molecular engineering calculations. Recently Curro and Schweizer developed a new approach for treating polymer liquids and mixtures which the authors call PRISM theory. This is an extension to polymers of the Reference Interaction Site Model (RISM Theory) developed by Chandler and Andersen to describe the statistical mechanics of small molecule liquids. The PRISM theory is a continuous space description of a polymer liquid, which includes chain connectivity and nonrandom mixing effects in a computationally tractable manner. The primary output from PRISM calculations is the average structure or packing of the amorphous liquid given by the radial distribution function denoted as g(r). This radial distribution function is employed to deduce thermodynamic or structural properties of interest. Here, the authors describe the theoretical approach and demonstrate its application to polyethylene, isotactic polypropylene, syndiotactic polypropylene, and polyisobutylene liquids and blends.

The magnitudes of accident dose risks calculated by the RADTRAN code depend directly on the time span between an accidental release and evacuation of the affected area surrounding potential radionuclide releases. In a previous study of truck and rail transportation accidents, and other incidents requiring evacuations, a lognormal distribution of evacuation times (time span from decision to evacuate until complete) was developed, which provided a better model for this parameter than the practice of using a highly conservative value of 24 hours. However, the distribution did not account for time required for responders to arrive on the scene, to evaluate the hazards to surrounding population and to initiate an evacuation. Data from US Department of Transportation (DOT) accident statistics have been collected and their distribution functions determined. The separate distribution functions were combined into a single, comprehensive distribution which may be sampled to supply values of the RADTRAN input parameter, EVACUATION. A sample RADTRAN calculation illustrating the effect on risks of using the distribution versus the original (24 hour), conservative point-estimate are also presented.

In the transport of radioactive material (RAM), e.g., spent nuclear fuel (SNF), stakeholders are generally most concerned about risks in high population density areas along transportation routes because of the perceived high consequences of potential accidents. The most significant portions of a transcontinental route and an alternative examined previously were evaluated again using population density data derived from US Census Block data. This method of characterizing population that adjoins route segments offers improved resolution of population density variations, especially in high population density areas along typical transport routes. Calculated incident free doses and accident dose risks for these routes, and the rural, suburban and urban segments are presented for comparison of their relative magnitudes. The results indicate that modification of this route to avoid major metropolitan areas through use of non-Interstate highways increases total risk yet does not eliminate a relatively small urban component of the accident dose risk. This conclusion is not altered by improved resolution of route segments adjoining high density populations.

Severe ship accidents and the probability of radioactive material release from spent reactor fuel casks were investigated previously. Other forms of RAM, e.g., plutonium oxide powder, may be shipped in large numbers of packagings rather than in one to a few casks. These smaller, more numerous packagings are typically placed in ISO containers for ease of handling, and several ISO containers may be placed in one of several holds of a cargo ship. In such cases, the size of a radioactive release resulting from a severe collision with another ship is determined not by the likelihood of compromising a single, robust package but by the probability that a certain fraction of 10`s or 100`s of individual packagings is compromised. The previous analysis involved a statistical estimation of the frequency of accidents which would result in damage to a cask located in one of seven cargo holds in a collision with another ship. The results were obtained in the form of probabilities (frequencies) of accidents of increasing severity and of release fractions for each level of severity. This paper describes an extension of the same general method in which the multiple packages are assumed to be compacted by an intruding ship`s bow until there is no free space in the hold. At such a point, the remaining energy of the colliding ship is assumed to be dissipated by progressively crushing the RAM packagings and the probability of a particular fraction of package failures is estimated by adaptation of the statistical method used previously. The parameters of a common, well characterized packaging, the 6M with 2R inner containment vessel, were employed as an illustrative example of this analysis method. However, the method is readily applicable to other packagings for which crush strengths have been measured or can be estimated with satisfactory confidence.

Even prior to the beginning of the nuclear age, the packaging and transportation of nuclear materials was a prime national concern. Nuclear materials such as uranium and plutonium had to be transported safely (and secretly) to the Manhattan Engineer District Laboratory in Los Alamos, New Mexico. The subsequent post war use of nuclear power for the generation of electricity and accelerated weapons development programs resulted in radioactive waste byproducts, such as spent fuel and plutonium, that were stored on site at utilities and federal weapons sites. While projected repositories for long term storage of radioactive waste are being planned, both low and high level radioactive materials on occasion must be moved safely. Movement to interim storage and, for low level waste, repository sites, is accomplished by a combination of truck, rail, ship, and air. The US Department of Energy (DOE) directs transportation activities including cask development technology for use in single or multimodal (a combination of land, water, and air) transport. In 1978, Sandia National Laboratories was selected as the lead contractor for basic transportation technology. This report is divided into the following topics: (1) early research and development (1936--1978); (2) radioactive material package test (1975--1977); (3) the SNL Transportation Technology Center; (4) TRUPACT-II; (5) beneficial uses of shipping system casks; (6) C-141B drop tests; (7) MIDAS; (8) MOSAIK; (9) SEARAM; (10) PATRAM; and (11) a chronology of transportation activities.

The Radioactive Materials Incident Report (RMIR) database was developed in 1981 at the Transportation Technology Center of Sandia National Laboratories to support its research and development activities for the US Department of Energy (DOE). This database contains information about radioactive materials transportation incidents that have occurred in the US since 1971. These data were drawn from the US Department of Transportation`s (DOT) Hazardous Materials Incident Report system, from Nuclear Regulatory Commission (NRC) files, and from various agencies including state radiological control offices. Support for the RMIR data base is funded by the National Transportation Program (EM-70) of the US Department of Energy. Transportation events in RMIR are classified in one of the following ways: as a transportation accident, as a handling accident, or as a reported incident. This presentation will provide definitions for these classifications and give examples of each. The primary objective of this presentation is to provide information on nuclear materials transportation accident incident events in the US for the period 1971--1997. Among the areas to be examined are: transportation accidents by mode, package response during accidents and an examination of accidents where release of contents has occurred.

Little guidance has been provided by the DOE for developing appropriate Operational Safety Requirements (OSR) for non-nuclear facility safety documents. For a period of time, Chapter 2 of DOE/AL Supplemental Order 5481.lB provided format guidance for non-reactor nuclear facility OSRs when this supplemental order applied to both nuclear and non-nuclear facilities. Thus, DOE Albuquerque Operations Office personnel still want to see non-nuclear facility OSRs in accordance with the supplemental order (i.e., in terms of Safety Limits, Limiting Conditions for Operation, and Administrative Controls). Furthermore, they want to see a clear correlation between the OSRs and the results of a facility safety analysis. This paper demonstrates how OSRs can be rather simply derived from the results of a risk assessment performed using the ``binning`` methodology of SAND95-0320.

An original computational technique to generate close-to-equilibrium dense polymeric structures is proposed. Diffusion of small gases are studied on the equilibrated structures using massively parallel molecular dynamics simulations running on the Intel Teraflops (9216 Pentium Pro processors) and Intel Paragon(1840 processors). Compared to the current state-of-the-art equilibration methods this new technique appears to be faster by some orders of magnitude.The main advantage of the technique is that one can circumvent the bottlenecks in configuration space that inhibit relaxation in molecular dynamics simulations. The technique is based on the fact that tetravalent atoms (such as carbon and silicon) fit in the center of a regular tetrahedron and that regular tetrahedrons can be used to mesh the three-dimensional space. Thus, the problem of polymer equilibration described by continuous equations in molecular dynamics is reduced to a discrete problem where solutions are approximated by simple algorithms. Practical modeling applications include the constructing of butyl rubber and ethylene-propylene-dimer-monomer (EPDM) models for oxygen and water diffusion calculations. Butyl and EPDM are used in O-ring systems and serve as sealing joints in many manufactured objects. Diffusion coefficients of small gases have been measured experimentally on both polymeric systems, and in general the diffusion coefficients in EPDM are an order of magnitude larger than in butyl. In order to better understand the diffusion phenomena, 10, 000 atoms models were generated and equilibrated for butyl and EPDM. The models were submitted to a massively parallel molecular dynamics simulation to monitor the trajectories of the diffusing species.

Under the sponsorship of the U.S. Department of Energy (DOE) Office of Utility Technologies, the Energy Storage Systems Analysis and Development Department at Sandia National Laboratories conducted a series of dialogs with industry regarding the uses and value of storage in stationary applications. The dialogs consisted of meetings with industry executives in which Energy Storage Systems (ESS) Program management solicited input regarding expected changes in the electric utility industry and the long-term research and development in storage technologies and systems that would be most appropriate for the emerging competitive business environment. This report is a compilation of the findings from this Executive Meetings Project.

Since the discovery of piezoresistivity in silicon in the mid 1950s. silicon-based pressure sensors have been widely produced. Micromachining technology has greatly benefited from the success of the integrated circuit industry, borrowing materials, processes, and toolsets. Because of this, microelectromechanical systems (MEMS) are now poised to capture large segments of existing sensor markets and to catalyse the development of new markets. Given the emerging importance of MEMS, it is instructive to review the history of micromachined pressure sensors, and to examine new developments in the field. Pressure sensors will be the locus of this paper, starting from metal diaphragm sensors with bonded silicon strain gauges, and moving to present developments of surface-micromachined, optical, resonant, and smart pressure sensors. Considerations for diaphragm design will be discussed in detail, as well as additional considerations for capacitive and piezoresistive devices. Results from surface-micromachined pressure sensors developed by the authors will be presented. Finally, advantages of micromachined sensors will be discussed.

Non-linear electromagnetic inversion schemes have been developed to produce 2D and 3D images of subsurface conductivity structure from electromagnetic geophysical data. The solutions are obtained by successive linearized model updates where full forward modeling is employed at each iteration to compute model sensitivities and predicted data. Regularization is applied to the problem to provide stability. The use of the inversion is demonstrated on a data set collected with the Apex Parametrics MaxMin I-8S over a section of conductive waste at the Idaho National Laboratory`s Cold Test Pit. The out-of -phase data are of very good quality while the in-phase are rather noisy due to slight mispositioning errors. A resolution study on synthetic data indicates that the error present in the in-phase data causes images of far lower resolution with more artifacts than if the in-phase and out-of-phase components are of similar quality. Better resolution images result if the data are weighted proportional to frequency; this gives each frequency equal importance. The loss of resolution due to poor quality in-phase data is demonstrated in a 3D inversion of the MaxMin data which shows both artifacts forming outside of the area known to contain the buried waste, as well as an inability to resolve depths.

This paper discusses criteria for selecting analytical support tools for manufacturing engineering in the early phases of product development, and the lessons learned at Sandia National Laboratories in selecting and applying these tools. The IPPD (Integrated Product and Process Design) process requires manufacturing process developers to be involved earlier than ever before in product development. Operating in an IPPD environment, Sandia`s manufacturing engineers were required to develop early estimates of the cost and performance of manufacturing plans. In early pre-production, there are very little actual data on manufacturing processes and almost no detailed data on the performance of various manufacturing process steps. The manufacturing engineer needs the capability to analyze various manufacturing process flows over a large set of assumptions involving capacity, resource requirements (equipment, labor, material, utilities,...), yields, product designs, etc. If the manufacturing process involves many process steps, or if there are multiple products in a single manufacturing area that share resources, or there are multiple part starts resulting in merged flow for final assembly, then this analysis capability must somehow be mechanized. This situation led them to look to modeling and simulation tools for a solution. Example analyses of manufacturing issues for two product sets in the early phases of product development are presented.

The electrical and chemical properties of insulators produced by codeposition of siloxane compounds or TEOS with oxygen in a focused ion beam (FIB) system were investigated. Metal-insulator-metal capacitor structures were fabricated and tested. Specifically, leakage current and breakdown voltage were measured and used to calculate the effective resistance and breakdown field. Capacitance measurements were performed on a subset of the structures. It was found that the siloxane-based FIB-insulators had superior electrical properties to those based on TEOS. Microbeam Rutherford backscattering spectrometry analysis and Fourier transform infrared spectroscopy were used to characterize the films and to help understand the differences in electrical behavior as a function of gas chemistry and deposition conditions. Finally, a comparison is made between the results presented here, previous results for FIB-deposited insulators, and typical thermally-grown gate oxides and interlevel dielectric SiO{sub 2} insulators.

In late 1993, the authors` mission expanded from engineering design to also encompass production of neutron generator devices. They completed a gap analysis of the tools needed to support this emerging production assignment and, as a result, introduced a Product Data Management (PDM) system. This implementation includes basic PDM features, Web access, interfaces to the production floor and suppliers, and other utilities. They carefully strategized, piloted and assessed the integration of the PDM system into their business. Their efforts have prepared them to enter the next tier to further integrate their key operational resources to include their external suppliers.

The temperature dependence of the specific contact resistance of W and WSi{sub 0.44} contacts on n{sup +} In{sub 0.65}Ga{sub 0.35}N and InN was measured in the range -50 {degrees}C to 125 {degrees}C. The results were compared to theoretical values for different conduction mechanisms, to further elucidate the conduction mechanism in these contact schemes for all but as-deposited metal to InN where thermionic emission appears to be the dominant mechanism. The contacts were found to produce low specific resistance ohmic contacts to InGaN at room temperature, e{sup c} {approximately} 10{sup -7} {Omega} {center_dot} cm{sup 2} for W and e{sub c} of 4x 10{sup -7} {Omega} {center_dot} cm{sup 2} for WSi{sub x}. InN metallized with W produced ohmic contacts with e{sub c} {approximately} 10{sup -7} {Omega} {center_dot} cm{sup 2} and e{sub c} {approximately} 10{sup -6} {Omega} {center_dot} cm{sup 2} for WSi{sub x} at room temperature.

Our studies of the shock compression response of PVDF polymer are continuing in order to understand the physical properties under shock loading and to develop high fidelity, reproducible, time-resolved dynamic stress gauges. New PVDF technology, new electrode configurations and piezoelectric analysis have resulted in enhanced precision gauges. Our new standard gauges have a precision of better than 1% in electric charge release under shock up to 15 GPa. The piezoelectric response of shock compressed PVDF gauges 1 mm{sup 2} in active area has been studied and yielded well-behaved reproducible data up to 20 GPa. Analysis of the response of these gauges in the {open_quotes}thin mode regime{close_quotes} using a Lagrangian hydrocode will be presented. P(VDF-TrFE) copolymers exhibit unique piezoelectric properties over a wide range of temperature depending on the composition. Their properties and phase transitions are being investigated. Emphasis of the presentation will be on key results and implications.

The wide gap materials SiC, GaN and to a lesser extent diamond are attracting great interest for high power/high temperature electronics. There are a host of device processing challenges presented by these materials because of their physical and chemical stability, including difficulty in achieving stable, low contact resistances, especially for one conductivity type, absence of convenient wet etch recipes, generally slow dry etch rates, the high temperatures needed for implant activation, control of suitable gate dielectrics and the lack of cheap, large diameter conducting and semi-insulating substrates. The relatively deep ionization levels of some of the common dopants (Mg, in GaN; B, Al in SiC; P in diamond) means that carrier densities may be low at room temperature even if the impurity is electrically active - this problem will be reduced at elevated temperature, and thus contact resistances will be greatly improved provided the metallization is stable and reliable. Some recent work with CoSi{sub x} on SiC and W-alloys on GaN show promise for improved ohmic contacts. The issue of unintentional hydrogen passivation of dopants will also be covered - this leads to strong increases in resistivity of p-SiC and GaN, but to large decreases in resistivity of diamond. Recent work on development of wet etches has found recipes for AlN (KOH), while photochemical etching of SiC and GaN has been reported. In the latter cases p-type materials is not etched, which can be a major liability in some devices. The dry etch results obtained with various novel reactors, including ICP, ECR and LE4 will be compared - the high ion densities in the former techniques produce the highest etch rates for strongly-bonded materials, but can lead to preferential loss of N from the nitrides and therefore to a highly conducting surface. This is potentially a major problem for fabrication of dry etched, recessed gate FET structures.

Sandia National Laboratories has developed a systematic approach for achieving high confidence in major products requiring high reliability for use in high-consequence applications. A high-consequence application is one in which product failure could result in significant loss of life, damage to major systems or to the environment, financial loss, or political repercussions. The application of this process has proven to be of significant benefit in the early identification, verification, and correction of potential product design and manufacturing process failure modes. Early identification and correction of these failures modes and the corresponding controls placed on safety-critical features, ensures product adherence to safety-critical design requirements, and enhances product quality, reliability, and the cost effectiveness of delivered products. Safety-critical features include design features such as materials and dimensions, as well as manufacturing features such as assembly processes, inspections, and testing.