Publications

Three dimensional multichip modules (MCMS) present an unusual challenge to the thermal designer. For example, high thermal resistance between upper planes of the MCM and the thermally anchored bottom plane can lead to the development of excessive temperatures. As new designs emerge, it becomes desirable to have methods of experimentally determining interior temperatures in the module in order to validate complex finite element calculations. In order to develop methods for assessing the thermal performance of a 3D MCM, we have developed a test module with three planes or slices. In this paper, we report on some initial calculations and measurements for the 3D MCM. In addition, we discuss the improvement in thermal performance obtained by replacing the top slice with a diamond substrate. Finite element method (FEM) thermal calculations have been done with both the workstation based analyzer P/Thermal from PDA Engineering and the PC program, Inertia from Modern Computer Aided Engineering. These analyses have assumed no heat losses by radiation or convection.

This report describes the linearly-polarized, loaded cavity-backed slot (LCBS) antenna developed for Reentry Vehicles (RVs) and the development process used by the Antenna Development Department. It includes typical antenna engineering design considerations or requirements, fabrication/assembly process, and performance characteristics. Antenna design theory is reduced to the basic concepts useful in designing LCBS antennas for reentry vehicles.

This document describes the components necessary to put together a video animation system. It is primarily intended for use at Sandia National Laboratories as it describes the components used in systems at Sandia. The main document covers the operation of the equipment in some detail and is intended for either the system maintainer or an advanced user. There is an appendix for each of the three systems in use by the Engineering Sciences Directorate which contain instructions for the general user.

A series of experiments has been performed on the Sandia HyperVelocity Launcher (HVL) to evaluate the effectiveness of a Whipple bumper shield to orbital space debris at impact velocities in excess of 10 km/s. Upon impact by a 0.67 g (0.87 mm thick) flier plate, the thin aluminum bumper shield disintegrates into a debris cloud. The debris cloud front propagates axially at velocities of {approximately}14 km/s and expands radially at a velocity of {approximately}7 km/s. Subsequent loading on a 3.2 mm thick aluminum substructure by the debris penetrates the substructure completely. However, when the mass of the flier plate is reduced to 0.33 g, the substructure, although damaged, is not perforated over the duration of the experiment. Numerical simulations performed using the multi-dimensional hydrodynamics code CTH also predict complete penetration of the substructure by the subsequent debris cloud for a 0.87 g flier plate. The numerical simulations for a 0.33 g flier plate show a strong dependence on assumed impact geometry. For the assumption of a spherical projectile impact geometry, perforation of the substructure by the subsequent debris cloud is not predicted by CTH.

This study involved the shock characterization of Diallyl Phthalate (DAP), in particular, the equation of state as measured by the shock Hugoniot. Tests were done between 1 and 11 GPa impact shock pressure. The Hugoniot parameters were determined to be: {rho}{sub 0}= 1.743, C{sub 0} = 2.20, and S = 2.33.

Nuclear power plants have experienced inadvertent actuations of fire protection systems (FPS) 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 plant equipment. This document provides a review of the impact of past occurrences of both types of such events on nuclear power plant safety. 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 includes seismic root causes and seismic/fire interaction. A quantification of these thirteen scenarios, where applicable, was performed on a Babcock and Wilcox Pressurized Water Reactor (lowered loop design). This report estimates the contribution of FPS actuations to core damage frequency and to risk.

Efficient use of a distributed memory parallel computer requires that the computational load be balanced across processors in a way that minimizes interprocessor communication. We present a new domain mapping algorithm that extends recent work in which ideas from spectral graph theory have been applied to this problem. Our generalization of spectral graph bisection involves a novel use of multiple eigenvectors to allow for division of a computation into four or eight parts at each stage of a recursive decomposition. The resulting method is suitable for scientific computations like irregular finite elements or differences performed on hypercube or mesh architecture machines. Experimental results confirm that the new method provides better decompositions arrived at more economically and robustly than with previous spectral methods. We have also improved upon the known spectral lower bound for graph bisection.

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

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

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

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

An inductively heated experiment SURC-1, using UO[sub 2]-ZrO[sub 2] material, was executed to measure and assess the thermal, gas, and aerosol source terms produced during core debris/concrete interactions. The SURC-1 experiment eroded a total of 27 cm of limestone concrete during 130 minutes of sustained interaction using 204.2 kg of molten prototypic UO[sub 2]-ZrO[sub 2] core debris material that included 18 kg of zr metal and 3.4 kg of fission product simulants. The melt pool temperature ranged from 2100 to 2400[degrees]C during the first 50 minutes of the test, followed by steady temperatures of 2000 to 2100[degrees]C during the middle portion of the test and temperatures of 1800 to 2000[degrees]C during the final 50 minutes of testing. The total erosion during the first 50 minutes was 16 cm with an additional 2 cm during the middle part of the test and 9 cm of ablation during the final 50 minutes. Aerosols were continuously released in concentrations ranging from 30 to 200 g/m[sup 3]. Comprehensive gas flow rates, gas compositions, and aerosol compositions were also measured during the SURC-1 test.

This document describes a panel discussion held on March 18, 1992 as part of a conference entitled ``Market Hub Technology`` . The purpose of the conference was to stimulate dialogue among various segments of the natural gas industry on the technology limits of an economic policy issue that has the potential to significantly alter the structure and functioning of the natural gas industry. Attendees included key US gas industry representatives, Federal Energy Regulatory Commission (FERC) commissioners, and others. The conference explored the concept of market centers, or hubs, and related technologies. It covered the technology currently available for the establishment of an integrated system of physical market hubs, and explored technology requirements for the further development of useful and efficient hubs. The discussion identified two primary barriers to the acceptance and implementation of a market center distribution system for natural gas. The first barrier is the potential change in the configuration of the market such a system would introduce and the resistance various industry segments would mount to such change. The second is the lack of industry standardization in the physical and business infrastructures.

A single EMCH concentrator module for the Photovoltaics for Utility Scale Application (PVUSA), Emerging Technologies-1 (EMT-1) program has been electrically and environmentally tested to the requirements in Sandia`s SAND86-2743 document ``Qualification Tests for Photovoltaic Concentrator Cell Assemblies; and Modules.`` Module testing was divided into three parts: (1) initial characterization, (2) environmental testing, and (3) supplemental testing. Testing began with module inspection for damage, adequate name plate information, grounding off-axis beam damage, and baseline electrical performance. The included thermal cycling, humidity/freeze cycling, rainwater intrusion, and hail impact, and hi-pot testing. After both thermal cycling and environmental testing, the module was electrically tested. The supplemental testing not required by the Sandia qualification document was conducted for engineering evaluation. These tests included wet insulation resistance measurements and cell temperature measurements after installation of heat sink fin extensions. The test sequence revealed some module deficiencies which include RTV adhesive/sealant problems, high cell temperatures, off-track beam damage, and low wet insulation resistance values.

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

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

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

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

SAFSIM (System Analysis Flow SIMulator) is a FORTRAN computer program to simulate the integrated performance of systems involving fluid mechanics, heat transfer, and reactor dynamics. SAFSIM provides sufficient versatility to allow the engineering simulation of almost any system, from a backyard sprinkler system to a clustered nuclear reactor propulsion system. In addition to versatility, speed and robustness are primary goals of SAFSIM. SAFSIM contains three basic physics modules: (1) a one-dimensional finite element fluid mechanics module with multiple flow network capability; (2) a one-dimensional finite element structure heat transfer module with multiple convection and radiation exchange surface capability; and (3) a point reactor dynamics module with reactivity feedback and decay heat capability. SAFSIM can be used for gas (compressible) or liquid (incompressible) single-phase flow systems with primary emphasis on gases (or supercritical fluids). This document contains a description of all the information required to create an input file for SAFSIM execution.

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

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

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

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

This report describes the features of monolithic, series connected photovoltaic converters which have been developed for applications where voltages are required that are higher than available using conventional single junction solar cells. These devices are intended to play a significant role in advanced weapon systems development. They are also appropriate for any other applications where electric power is needed in remote regions and electrical connection to the region is deemed detrimental for whatever reasons. Development of this technology at two outside contractors has been accomplished through competitive procurement in response to an internally generated Statement of Work. Detailed comparisons are made of data taken from converters of each type from both contractors. The primary advantage of these converters is that they are high voltage/low current devices compared to conventional single junction solar cells. This allows them to directly drive a wider range of loads without the necessity of power conditioning, such as provided by a transformer. Discussions of load analysis for given applications are included.

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