A two-stage self-organizing neural network architecture has been applied to object recognition in Synthetic Aperture Radar imagery. The first stage performs feature extraction and implements a two-layer Neocognitron. The resulting feature vectors are presented to the second stage, an ART 2-A classifier network, which clusters the features into multiple target categories. Training is performed off-line in two steps. First, the Neocognitron self-organizes in response to repeated presentations of an object to recognize. During this training process, discovered features and the mechanisms for their extraction are captured in the excitatory weight patterns. In the second step, Neocognitron learning is inhibited and the ART 2-A classifier forms categories in response to the feature vectors generated by additional presentations of the object to recognize. Finally, all training is inhibited and the system tested against a variety of objects and background clutter. In this paper we report the results of our initial experiments. The architecture recognizes a simulated tank vehicle at arbitrary azimuthal orientations at a single depression angle while rejecting clutter and other object returns. The neural architecture has achieved excellent classification performance using 20 clusters.
The effects of orientation and stress on chemically prepared Pb(Zr,Ti)O3 (PZT) film properties have been determined. Systematic modification of the underlying substrate technology has made it possible to fabricate suites of films that have various degrees of orientation at a constant stress level, and to fabricate films that are in different states of stress but have similar orientation. Highly oriented films of the following compositions have been fabricated: PZT 60/40, PZT 40/60, and PZT 20/80. Remanent polarizations ( approximately=60 mu C/cm2) greater than those of the best bulk polycrystalline ferroelectrics were obtained for PZT 40/60 films that were under compression and highly.
This paper presents results of a set of numerical experiments performed bo benchmark the Cell-Centered Implicit Continuous-fluid Eulerian (CCICE), and to determine their limitations as flow solvers for water entry and water exit simulations.
Translations of two pioneering Russian papers on antenna theory are presented. The first paper provides a treatise on finite-length dipole antennas; the second paper addresses infinite-length, impedance-loaded transmitting antennas.
This paper will include a brief overview of the components of the QUICKSILVER suite and its current modeling capabilities. As time permits, results from sample applications will be shown, including time animations of simulation results.
The UNIX LANs in 1500 are experiencing explosive growth. The individual departments are creating LANs to address their particular needs; however, at the same time, shared software tools between the departments are becoming more common. It is anticipated that users will occasionally need access to various department software and/or LAN services, and that support personnel may carry responsibilities which require familiarization with multiple environments. It would be beneficial to users and support personnel if the various department environments share some basic similarities, allowing somewhat transparent access. This will become more important when departments share specific systems, as 1510 and 1550 have proposed with an unclassified UNIX system. Therefore, standards/conventions on the department LANs and the central site systems have to be established to allow for these features. it should be noted that the goal of the UEC is to set standards/conventions which affect the users and provide some basic structure for software installation and maintenance; it is not the intent that all 1500 LANs be made identical at an operating system and/or hardware level. The specific areas of concern include: (1) definition of a non-OS file structure; (2) definition of an interface for remote mounted file systems; (3) definition of a user interface for public files; (4) definition of a basic user level environment; and (5) definition of documentation requirements for public files (shared software). Each of these areas is addressed in this paper.
This document contains implementation details for the Sandia Management Restructure Study Team (MRST) Prototype Information System, which resides on a Sun SPARC II workstation employing the INGRES RDBMS. The INGRES/Windows 4GL application editor was used to define the components of the two user applications which comprise the system. These specifications together with the MRST information model and corresponding database definition constitute the MRST Prototype Information System technical specification and implementation description presented herein. The MRST Prototype Information System represents a completed software product which has been presented to the Management Restructure Study Team to support the management restructing processes at Sandia National Laboratories.
Finite element analyses of oil-filled caverns were performed to investigate the effects of cavern depth on surface subsidence and storage loss, a primary performance criteria of SPR caverns. The finite element model used for this study was axisymmetric, approximating an infinite array of caverns spaced at 750 ft. The stratigraphy and cavern size were held constant while the cavern depth was varied between 1500 ft and 3000 ft in 500 ft increments. Thirty year simulations, the design life of the typical SPR cavern, were performed with boundary conditions modeling the oil pressure head applied to the cavern lining. A depth dependent temperature gradient of 0.012{degrees}F/ft was also applied to the model. The calculations were performed using ABAQUS, a general purpose of finite element analysis code. The user-defined subroutine option in ABAQUS was used to enter an elastic secondary creep model which includes temperature dependence. The calculations demonstrated that surface subsidence and storage loss rates increase with increasing depth. At lower depths the difference between the lithostatic stress and the oil pressure is greater. Thus, the effective stresses are greater, resulting in higher creep rates. Furthermore, at greater depths the cavern temperatures are higher which also produce higher creep rates. Together, these factors result in faster closure of the cavern. At the end of the 30 year simulations, a 1500 ft-deep cavern exhibited 4 percent storage loss and 4 ft of subsidence while a 3000 ft-deep cavern exhibited 33 percent storage loss and 44 ft of subsidence. The calculations also demonstrated that surface subsidence is directly related to the amount of storage loss. Deeper caverns exhibit more subsidence because the caverns exhibit more storage loss. However, for a given amount of storage loss, nearly the same magnitude of surface subsidence was exhibited, independent of cavern depth.
This economic analysis compares human and robotic TRUPACT unloading at the Waste Isolation Pilot Plant. Robots speed up the unloading process, reduce human labor requirements, and reduce human exposure to radiation. The analysis shows that benefit/cost ratios are greater than one for most cases using government economic parameters. This suggests that robots are an attractive option for the TRUPACT application, from a government perspective. Rates of return on capital investment are below 15% for most cases using private economic parameters. Thus, robots are not an attractive option for this application, from a private enterprise perspective.
Proceedings of the 35th International Power Sources Symposium
Clark, N.H.
Technologies that use carbon and mixed metal oxides as the electrode material have been pursued for the purpose of producing high-reliability double-layer capacitors (DLCs). The author demonstrates their environmental stability in temperature, shock, vibration, and linear acceleration. She reviews the available test data for both types of DLCs under these stress conditions. This study suggests that mixed metal oxides and carbon-based double-layer capacitors can survive robust environments if packaged properly, and that temperature decreases performance of double-layer capacitors.
We describe a simple engineering model applicable to stand-off “Whipple bumper” shields, which are used to protect space-based assets from impacts by orbital debris particles. The model provides a framework for analyzing: 1) the parameter limits governing the penetration and breakup or decomposition of the hypervelocity debris particle; 2) the behavior of the induced debris cloud, including its velocity and divergence; and 3) the design and optimization of the stand-off shield for a specific threat and level of protection required. The model is normalized to actual stand-off debris shield experiments and multi-dimensional numerical simulations at impact velocities of ~10 km/s. The subsequent analysis of a current space station shield design suggests that: 1) for acceptable levels of protection, stand-off shields can be significantly thinner than previously thought; and 2) with the proper balance between shield thickness and stand-off distance, the total shield mass can be reduced substantially.
A series of experiments has been performed on the Sandia Hypervelocity Launcher to determine the performance limits of conventional Whipple shields against representative 0.8 g aluminum orbital debris plate-like fragments with velocities of 7 and 10 km/s. Supporting diagnostics include flash X-rays, high speed photography and transient digitizers for timing correlation. Two Whipple shield designs were tested with either a 0.030 cm or a 0.127 cm thick front sheet and a 0.407 cm thick backsheet separated by 30.5 cm. These two designs bracket the ballistic penetration limit curve for protection against these debris simulants for 7 km/s impacts.
This document describes the Temperature Monitoring System for the RHEPP project at Sandia National Laboratories. The system is designed to operate in the presence of severe repetitive high voltage and electromagnetic fields while providing real time thermal data on component behavior. The thermal data is used in the design and evaluation of the major RHEPP components such as the magnetically switched pulse compressor and the linear induction voltage adder. Particular attention is given to the integration of commercially available hardware and software components with a custom written control program. While this document is intended to be a reference guide, it may also serve as a template for similar applications. 3 refs.
Lecture Notes in Computer Science (including subseries Lecture Notes in Artificial Intelligence and Lecture Notes in Bioinformatics)
Greenberg, David S.
The Choice Coordination Problem with k alternatives (k-CCP) was introduced by Rabin in 1982 [Rab82]. The goal is to design a wait-free protocol for n asynchronous processes which causes all correct processes to agree on one out of k possible alternatives. The agreement on a single choice is complicated by the fact that there is no a priori agreement on names for the alternatives. Furthermore processes must state their choice and do all communication via registers associated with the alternatives. We exactly characterize when the k-CCP can be solved deterministiclly, prove upper and lower space bounds for deterministic solutions, and provide a randomized protocol which is significantly better than the deterministic lower bound.
This bibliography contains 34 references concerning utilizing benchmarking in the management of businesses. Books and articles are both cited. Methods for gathering and utilizing information are emphasized. (GHH)
Final Program and Paper Summaries for the 1992 Digital Signal Processing Workshop, DSPWS 1992
Jakowatz Jr., C.V.; Thompson, P.A.
In this paper we take a new look at the tomographic formulation of spotlight mode synthetic aperture radar (SAR), so as to include the case of targets having three-dimensional structure. This bridges the work of David C. Munson and his colleagues, who first described SAR in terms of two-dimensional tomography, with Jack Walker`s original derivation of spotlight mode SAR imaging via Doppler analysis. The main result is to demonstrate that the demodulated radar return data from a spotlight mode collection represent a certain set of samples of the three-dimensional Fourier transform of the target reflectivity function, and to do so using tomographic principles instead of traditional Doppler arguments. We then show that the tomographic approach is useful in interpreting the two-dimensional SAR image of a three-dimensional scene. In particular, the well-known SAR imaging phenomenon commonly referred to as layover is easily explained in terms of tomographic projection. 4 refs.
The unit cell shape of thick frequency selective surfaces, or dichroic plate, is dependent on its frequency requirements. One aperture shape may be chosen to give wider bandwidths, and another chosen for sharper frequency roll-off. This is analogous to circuits where the need for differing frequency response determines the circuit topology. Acting as spatial frequency filters, dichroics are a critical component in supporting the Deep Space Network (DSN) for spacecraft command a control up links as well as spacecraft down links. Currently these dichroic plates separate S-band at 2.0--232 GHz from X-band at 8.4--8.45 GHz. But new spacecraft communication requirements are also calling for an up link frequency at 7.165 GHz. In addition future spacecraft such as Craft/Casssini will require dichroics effectively separating K{sub a}-band frequencies in the 31--35 GHz range. The requirements for these surfaces are low transmission loss of < 0.1 dB at high power levels. Also is important to maintain a minimal relative phase shift between polarizations for circular polarization transmission. More current work has shown the successful demonstration of design techniques for straight, rectangular apertures at an incident angle of 30{degrees}. The plates are air-filled due to power dissipation and noise temperature considerations. Up-link frequency powers approach 100 kW making dielectrics undesirable. Here we address some of the cases in which the straight rectangular shape may have limited usefulness. For example, grating lobes become a consideration when the bandwidth required to include the new frequency of 7.165 GHz conflicts with the desired incident angle of 30{degrees}. For this case, the cross shape`s increased packing density and bandwidth could make it desirable. When a sharp frequency response is required to separate two closely space K{sub a}-band frequencies, the stepped rectangular aperture might be advantageous. 5 refs.
Phase II of the Long Valley Exploratory Well was completed to a depth of 7588 feet in November 1991. The drilling comprised two sub-phases: (1) drilling 17-1/2 inch hole from the Phase I casing shoe at 2558 feet to a depth of 7130 feet, plugging back to 6826 feet, and setting 13-3/8 inch casing at 6825 feet, all during August--September 1991; and (2) returning in November to drill a 3.85-inch core hole deviated out of the previous wellbore at 6868 feet and extending to 7588 feet. Ultimate depth of the well is planned to be 20,000 feet, or at a bottomhole temperature of 500{degrees}C, whichever comes first. Total cost of this drilling phase was approximately $2.3 million, and funding was shared about equally between the California Energy Commission and the Department of Energy. Phase II scientific work will commence in July 1992 and will be supported by DOE Office of Basic Energy Sciences, DOE Geothermal Division, and other funding sources.
Several closed form trajectory solutions have been developed for low-thrust interplanetary flight and used with patched conies for analysis of combined propulsion systems. The solutions provide insight into alternative types of Mars missions, and show considerable mass savings for fast crewed missions with outbound trip times on the order of 90-100 days.
Nuclear Thermal Propulsion (NTP) has been identified as a critical technology in support of the NASA Space Exploration Initiative (SEI). In order to safely develop a reliable, reusable, long-lived flight engine, facilities are required that will support ground tests to qualify the nuclear rocket engine design. Initial nuclear fuel element testing will need to be performed in a facility that supports a realistic thermal and neutronic environment in which the fuel elements will operate at a fraction of the power of a flight weight reactor/engine. Ground testing of nuclear rocket engines is not new. New restrictions mandated by the National Environmental Protection Act of 1970, however, now require major changes to be made in the manner in which reactor engines are now tested. These new restrictions now preclude the types of nuclear rocket engine tests that were performed in the past from being done today, A major attribute of a safely operating ground test facility is its ability to prevent fission products from being released in appreciable amounts to the environment. Details of the intricacies and complications involved with the design of a fuel element ground test facility are presented in this report with a strong emphasis on safety and economy.
A rapid deployment access delay system (RAPADS) has been designed to provide high security protection of valued assets. The system or vault is transportable, modular, and utilizes a pin connection design. Individual panels are attached together to construct the vault. The pin connection allows for quick assembly and disassembly, and makes it possible to construct vaults of various sizes to meet a specific application. Because of the unique pin connection and overlapping joint arrangement, a sequence of assembly steps are required to assembly the vault. As a result, once the door is closed and locked, all pin connections are concealed and inaccessible. This provides a high level of protection in that no one panel or connection is vulnerable. This paper presents the RAPADS concept, design, fabrication, and construction.
One of the most challenging applications facing the computer community is development of effective adaptive human-computer interface. This challenge stems from the complex nature of the human part of this symbiosis. The application of this discipline to the environmental restoration and waste management is further complicated due to the nature of environmental data. The information that is required to manage environmental impacts of human activity is fundamentally complex. This paper will discuss the efforts at Sandia National Laboratories in developing the adaptive conceptual model manager within the constraint of the environmental decision-making. A computer workstation, that hosts the Conceptual Model Manager and the Sandia Environmental Decision Support System will also be discussed.
The Yucca Mountain Site Characterization Project is studying Yucca Mountain in southwestern Nevada as a potential site for a high-level nuclear waste repository. Site characterization includes surface-based and underground testing. Analyses have been performed to design site characterization activities with minimal impact on the ability of the site to isolate waste, and on tests performed as part of the characterization process. One activity of site characterization is the construction of an Exploratory Studies Facility, consisting of underground shafts, drifts, and ramps, and the accompanying surface pad facility and roads. The information in this report addresses the following topics: (1) a discussion of the potential effects of surface construction water on repository-performance, and on surface and underground experiments; (2) one-dimensional numerical calculations predicting the maximum allowable amount of water that may infiltrate the surface of the mountain without affecting repository performance; and (3) two-dimensional numerical calculations of the movement of that amount of surface water and how the water may affect repository performance and experiments. The results contained herein should be used with other site data and scientific/engineering judgement in determining controls on water usage at Yucca Mountain. This document contains information that has been used in preparing Appendix I of the Exploratory Studies Facility Design Requirements document for the Yucca Mountain Site Characterization Project.
The focus of this paper is on changes in perceptions of the risks associated with nuclear waste management over time. In particular, we are interested in the kinds of change that take place when the management programs, and those who are charged with implementing them, are subject to intensive public debate over an extended period of time. We are undertaken an over-time study of perceived risks in Colorado and New Mexico by implementing sequential random household surveys in each state, timed at six month intervals. This study employs three of these surveys, spanning the period from summer, 1990 to summer, 1991. Using these data, we examine the dynamics that may underlie variations in perceived risks over time. In particular, our analysis is focused on changes in the roles played by (1) basic political orientations (i.e. political ideology) and (2) trust in those who advocate conflicting policy positions.
Midway Valley, located at the eastern base of the Yucca Mountain in southwestern Nevada, is the preferred location of the surface facilities for the potential high-level nuclear waste repository at Yucca Mountain. One goal in siting these surface facilities is to avoid faults that could produce relative displacements in excess of 5 cm in the foundations of the waste-handling buildings. This study reviews existing geologic and geophysical data that can be used to assess the potential for surface fault rupture within Midway Valley. Dominant tectonic features in Midway Valley are north-trending, westward-dipping normal faults along the margins of the valley: the Bow Ridge fault to the west and the Paintbrush Canyon fault to the east. Published estimates of average Quaternary slip rates for these faults are very low but the age of most recent displacement and the amount of displacement per event are largely unknown. Surface mapping and interpretive cross sections, based on limited drillhole and geophysical data, suggest that additional normal faults, including the postulated Midway Valley fault, may exist beneath the Quaternary/Tertiary fill within the valley. Existing data, however, are inadequate to determine the location, recency, and geometry of this faulting. To confidently assess the potential for significant Quaternary faulting in Midway Valley, additional data are needed that define the stratigraphy and structure of the strata beneath the valley, characterize the Quaternary soils and surfaces, and establish the age of faulting. The use of new and improved geophysical techniques, combined with a drilling program, offers the greatest potential for resolving subsurface structure in the valley. Mapping of surficial geologic units and logging of soil pits and trenches within these units must be completed, using accepted state-of-the-art practices supported by multiple quantitative numerical and relative age-dating techniques.
Sandia National Laboratories (SNL) is a Department of Energy multiprogram engineering and scientific facility with unique design, development, and test capabilities arising from their work in nuclear weapons, energy resources, defense systems, nuclear safeguards, and specialized scientific endeavors. To support these programs, they have developed instrumentation and telemetry expertise not available elsewhere. This technology is applicable to projects in government and industry. Since the 1950s, they have applied our technical competence to meet difficult challenges with innovative solutions to data acquisition and telemetry problems. Sandia - with experience in fields as diverse as parachute design and plasma physics, geology and rocket guidance, human factors and high-speed aerodynamics, non-destructive testing and satellite communications - can use the power of synergism among our many disciplines to solve your complex problems of data and acquisition and analysis. SNL solves difficult data acquisition problems for extreme environments with expertise in advanced telemetry techniques, high data rate telemetry design, specialized electronics packaging, MIL-STD-1553 communications, instrumentation development, real-time data analysis, project management, specialized testers and data encryption.
Pretest analysis of a heated block test, proposed for the Exploratory Studies Facility at Yucca Mountain, Nevada, was conducted in this investigation. Specifically, the study focuses on the evaluation of the various designs to drill holes and cut slots for the block. The thermal/mechanical analysis was based on the finite element method and a compliant-joint rock-mass constitutive model. Based on the calculated results, relative merits of the various test designs are discussed.
Photovoltaic energy systems have historically been treated as a bulk power generation source for the future. However, utilities and other agencies involved with electrification throughout the world are beginning to find photovoltaics a least-cost option to meet specific loads both for themselves and their customers, in both off-grid and grid-connected applications. These expanding markets offer the potential of hundreds of megawatts of sales in the coming decade, but a strategy addressing both industrial growth and user acceptance is necessary to capitalize on this opportunity. 11 refs.
Phase mixing of transverse oscillations changes the nature of the ion hose instability from an absolute to a convective instability. The stronger the phase mixing, the faster an electron beam reaches equilibrium with the guiding ion channel. This is important for long distance propagation of relativistic electron beams where it is desired that transverse oscillations phase mix within a few betatron wavelengths of injection and subsequently an equilibrium is reached with no further beam emittance growth. In the linear regime phase mixing is well understood and results in asymptotic decay of transverse oscillations as 1/Z{sup 2} for a Gaussian beam and channel system, Z being the axial distance measured in betatron wavelengths. In the nonlinear regime (which is likely mode of propagation for long pulse beams) results of the spread mass model indicate that phase mixing is considerably weaker than in the regime. In this paper we consider this problem of phase mixing in the nonlinear regime. Results of the spread mass model will be shown along with a simple analysis of phase mixing for multiple oscillator models. Particle simulations also indicate that phase mixing is weaker in nonlinear regime than in the linear regime. These results will also be shown. 3 refs., 4 figs.
Photovoltaic (PV) systems are increasing in popularity in the northern latitudes and in the arctic regions in the state of Alaska. This increased interest and the high cost of providing electric power in these remote areas have prompted the Alaska Energy Authority (AEA) to request assistance from the Photovoltaic Design Assistance Center at Sandia National Laboratories. A project to investigate the feasibility of using PV-Diesel hybrid power systems in small villages in Alaska was started in 1989. Data acquisition systems (DAS) were designed and installed in selected villages to obtain resource and load information. The DAS is described and village electrical and resource data are presented. Simulations were run using the collected village data and actual cost data provided by the AEA. Results of the simulations and the economic analysis are presented. 5 refs., 8 figs.
Fabrication of high-efficiency silicon solar cells in an industrial environment requires a different optimization than in a laboratory environment. Strategies are presented for process development of high-efficiency silicon solar cells, with a goal of simplifying technology transfer into an industrial setting. The strategies emphasize the use of statistical experimental design for process optimization, and the use of baseline processes and cells for process monitoring and quality control. 8 refs.
The purpose of this paper is to develop an analytical model to convert ballistic limit curves obtained from flat projectile experiments to ballistic limit curves based on equivalent diameter spheres. Results from a test program involving flat plat projectiles conducted at Sandia National Laboratories are compared against the predicted performance of equivalent spherical projectiles as determined from the Wilkinson and Cour-Palais penetration equations. The developed method demonstrates good correlation of the ballistic limit of the shield concept for the flat plate projectiles to the theoretical ballistic limit for equivalent spheres as predicted by the penetration equations. 3 refs.
PRA studies are being extended to include a wider spectrum of reactor plants than was considered in NUREG-1150. There is a need for computationally simple models for Direct Containment Heating (DCH) that could be used for screening studies aimed at identifying potentially significant contributors to risk. This paper discusses two adiabatic equilibrium models that are candidates for the task. The first, a 1-cell model, places a true upper bound on DCH loads. This upper bound, however, often far exceeds reasonable expectations of containment loads based on best estimate CONTAIN calculations or experiment observations. In this paper, a 2-cell model is developed that largely captures the major mitigating features of containment compartmentalization, thus providing more reasonable estimates of the containment load. Predictions of the equilibrium models are compared with experiment data from the Limited Flight Path (LFP) test series conducted at Sandia National Laboratories.
The CONTAIN code is currently being used to predict containment thermal hydraulic conditions during design basis and severe accidents for advanced light water reactor (ALWR) designs such as the Westinghouse AP600. In the AP600 design, a passive containment cooling system (PCCS) is used for reducing long-term overpressure during accidents. CONTAIN models for heat and mass transfer within the AP600 containment and outer air cooling channel are verified by comparing recent CONTAIN calculations to integral test data obtained by Westinghouse in their PCCS Integral Test Facility. The comparison includes test in which the outer containment wall is both dry and wet, that is, the wet tests involve an evaporative water film that enhances heat transfer as will be the case for AP600. The appropriateness of the heat and mass transfer analogy methodology used in the CONTAIN code is demonstrated. Code model limitations are discussed along with model development plans and applications for AP600.
An additive three step process has been developed for patterned deposition of Cu onto poly(tetrafluoroethylene) (PTFE). The first step involves patterned irradiation with X-rays or electrons which is thought to cross link the PTFE surface; step two involves chemical etching with the result that only the non-irradiated areas are etched; and step three involves selective chemical vapor deposition (CVD) of Cu onto the etched surface at 200 C using (hexafluoroacetylacetonato)Cu(I) trimethylphosphine ((hfac)Cu(PMe{sub 3})). The non-irradiated areas of the surface are covered by a continuous, dense Cu film with X-ray photoelectron spectra show to contain only surface impurities that are easily removed by a short Ar ion sputter. The irradiated areas show the presence of only C and F, characteristic of PTFE.
The first experiment of the Integral Effects Test (IET-1) series was conducted to investigate the effects of high pressure melt ejection (HPME) on direct containment heating (DCH). A 1:10 linear scale model of the Zion reactor pressure vessel (RPV), cavity, instrument tunnel, and subcompartment structures were constructed in the Surtsey Test Facility at Sandia National Laboratories (SNL). The RPV was modelled with a melt generator that consisted of a steel pressure barrier, a cast MgO crucible, and a thin steel inner liner. The melt generator/crucible had a semi-hemispherical bottom head containing a graphite limitor plate with a 3.5 cm exit hole to simulate the ablated hole in the RPV bottom head that would be formed by tube ejection in a severe nuclear power plant (NPP) accident. The reactor cavity model contained 3.48 kg of water with a depth of 0.9 cm that corresponded to condensate levels in the Zion plant. A steam driven iron oxide/aluminum/chromium thermite was used to simulate HPME. A relatively small steam explosion occurred in the cavity during IET-1. Steam blowthrough entrained debris into the Surtsey vessel resulting in a peak pressure increase in Surtsey of 98 kPa. The Surtsey vessel had been previously inerted with N{sub 2}. The total debris mass ejected into the Surtsey vessel was 43 kg. The hydrogen concentration was 3.1 mol.% in the vessel at equilibrium. The concentration measured inside the subcompartment structures immediately following HPME transient was 20.7 mol.% H{sub 2}. 4 refs., 17 figs., 5 tabs.
During the RADLAC II open-air beam propagation experiments this last year three separate optical diagnostics were used. (1) Streak cameras were deployed to measure matched beam radius and centroid versus time. (2) Three gated, intensified TV cameras were used to image the beam from the end of the propagation range. They gave beam radius and centroid for three slices of the beam over a five meter propagation length. (3) Open shutter cameras were developed to give the time-averaged beam position over the entire propagation range. Data from all three diagnostics were digitized, stored in files on a computer, and post-processed to give temporally and spatially resolved beam size and position. These diagnostics used beam induced air-fluorescence as the mechanism to provide a prompt signal representative of the beam current density. Previous experiments and analysis have shown that the radiation is prompt with the intensity proportional to the beam current density for high energy, high current electron beams propagating in full density air.
Detailed geometric models have been used within a graphical simulation environment to study transportation cask facility design and to perform design and analyses of robotic systems for handling of nuclear waste. The models form the basis for a robot control environment which provides safety, flexibility, and reliability for operations which span the spectrum from autonomous control to tasks requiring direct human intervention.
We have designed and manufactured a test chip devoted to the study of interconnect voiding. The test chip is suitable for evaluating theoretical models, acceleration recipes, and the effects of process variations. We describe the chip and a simple, stress-free packaging technique that eliminates any stress to the chip from die bonding or packaging thermal cycles. With this test chip, we can perform many necessary and desirable experiments: determining stress, observing or stimulating void growth, profiling hydrogen concentrations, and measuring excess current noise. We report here preliminary measurements of residual stress, observations of voids, and determinations of hydrogen concentrations of hydrogen concentration under variations in aluminum annealing and passivation. In agreement with observations elsewhere, we find that passivations which differ greatly in intrinsic stress do not differ much in the stress they impart to patterned metal; some workers have suggested instead that excess hydrogen in the aluminum contributes to voiding. Following this lead, we have used nuclear reaction analysis to profile the hydrogen concentration in passivation, metallization, barrier metal, and interlevel dielectric and present some preliminary measurements here. We conclude that passivated metallization may contain as much as 0.1 atomic % hydrogen. 10 refs.
This paper provides a summary and status report for two ongoing experimental programs. The purpose of each program is to determine the behavior of certain components of the containment pressure boundary when subjected to severe accident conditions. The first program is investigating the effect of various parameters on tearing of the steel liner in reinforced concrete containments. The second will attempt to determine if worst-case containment loading conditions are capable of causing leakage through piping penetration bellows. The liner test program is almost complete; however, the bellows tests have not yet begun. Therefore, the emphasis of the paper is on the liner experiments. The research activities described herein are a part of the Containment Integrity Programs, which are managed by Sandia National Laboratories for the US Nuclear Regulatory Commission.
A Science Advisor Program has been established at Sandia National Laboratories (SNL) for the long term augmentation of math and science instruction in New Mexico schools. Volunteer SNL engineers and scientists team with the faculty of participating schools to enhance the teachers` abilities to capture and hold the student`s scientific imagination and develop their scientific skills. This is done primarily through providing laboratory resources, training the teachers how to use those resources, and advising how to obtain them in the future. In its first year, over 140 advisors teamed with 132 schools, for average weekly contact with 500 teachers and 10,000 students. Surveys indicate a general rise in frequency and quality of hands-on science instruction, as well as teacher and student attitudes. An expanded evaluation is planned for subsequent years.
The syntheses and physical properties of {kappa}-(ET){sub 2}Cu[N(CN){sub 2}]X (X=Br and Cl) are summarized. The {kappa}-(ET){sub 2}Cu[N(CN){sub 2}]Br salt is the highest {Tc} radical-cation based ambient pressure organic superconductor ({Tc}=11.6 K), and the {kappa}-(ET){sub 2}Cu[N(CN){sub 2}]Cl salt becomes a superconductor at even higher {Tc} under 0.3 kbar hydrostatic pressure ({Tc}=12.8 K). The similarities and differences between {kappa}-(ET){sub 2}Cu[N(CN){sub 2}]Br and {kappa}-(ET){sub 2}Cu(NCS){sub 2} ({Tc}=10.4 K) are presented. The X-ray structures at 127 K reveal that the the S{hor_ellipsis}S contacts shorten between ET dimers in the former compound while the S{hor_ellipsis}S contacts shorten within dimers in the latter. The difference in their ESR linewidth behavior is also explained in terms of the structural differences. A semiconducting compound, (ET)Cu[N(CN){sub 2}]{sub 2}, isolated during {kappa}-(ET){sub 2}Cu[N(CN){sub 2}]Cl synthesis is also reported. The ESR measurements of the {kappa}-(ET){sub 2}Cu[N(CN){sub 2}]Cl salt indicate that the phase transition near 40 K is similar to the spin density wave transition in (TMTSF){sub 2}SbF{sub 6}. A new class of organic superconductors, {kappa}-(ET){sub 2}Cu{sub 2}(CN){sub 3} and {kappa}-(ET){sub 2}Cu{sub 2}(CN){sub 3}-{delta}Br{delta}, is reported with {Tc}`s of 2.8 K (1.5 kbar) and 2.6 K (1 kbar), respectively.
We describe a new electrochemical processing technique based on porous silicon formation that can produce surface and buried insulators, conductors, and sacrificial layers required for silicon micromachining to fabricate micromechanical devices and sensors. Porosity and thickness of porous silicon layers for micromachining can be controlled to a relative precision better than 0.3% for porosities ranging from 20--80% and thicknesses ranging from sub- micron to hundreds of microns. The technique of using porous silicon has important implications for microfabrication of silicon electromechanical devices and sensors. The high relative precision in realizing a given thickness is superior to that obtained with conventional chemical etches. 8 refs.
This paper discusses the development of the software for Source Term Analyses for Containment Evaluations (STACE). This software is being developed for the Source Term Technical Issue Resolution Program at Sandia National Laboratories (SNL) in support of the Cask Systems Development Program (CSDP) that is sponsored by the US Department of Energy`s Office of Civilian Radioactive Waste Management (OCRWM). STACE is a system of computer codes operating under a graphics-based controller that performs source term analysis of spent fuel transport casks. Output from STACE includes the cladding breach probability, the releasable radionuclide concentrations, and maximum permissible gas flow rates past the closure seals. STACE is anticipated being used for on- and off-site situations related to the handling and transport of spent fuel casks.
This paper presents a methodology for determining the response of spent fuel assembly spacer grids subjected to transport cask impact loading. The spacer grids and their interaction with rod-to-rod loading are the most critical components governing the structural response of spent fuel assemblies. The purpose of calculating the assembly response is to determine the resistance to failure of spent fuel during regulatory transport. The failure frequency computed from these analyses is used in calculating category B spent fuel cask containment source term leakage rates for licensing calculations. Without defensible fuel rod failure frequency prediction calculations, assumptions of 100% fuel failure must be made, leading to leak tight cask design requirements.
A methodology for determining the probability spent-fuel cladding breach due to normal and accident class B cask transport conditions is introduced. This technique uses deterministic stress analysis results as well as probabilistic cladding material properties, initial flaws, and breach criteria. Best estimates are presented for the probability distributions of irradiated Zircaloy properties such as ductility and fracture toughness, and for fuel rod initial conditions such as manufacturing flaws and PCI part-wall cracks. Example analyses are used to illustrate the implementation of this methodology for a BWR (GE 7 {times} 7) and a PWR (B&W 15 {times} 15) assembly. The cladding breach probabilities for each assembly are tabulated for regulatory normal and accident transport conditions including fire.
Residual stress states that are a direct result of fabrication and processing are known to exist inside wound capacitors. Considerable insights into the nature of these mechanical and thermomechanical stress states have been gained through the application of analytical prediction capabilities that have been developed for that purpose. For example, analysis shows where roll slip may occur in the capacitor due to steep wound tension gradients or low radial pressures, and how the tension loss of individual plies is distributed throughout the capacitor. Significant tension loss differences between dielectric and conducting plies has also been predicted, with conducting plies not only losing their initial winding tension, but actually experiencing a net compressive value of wound tension. While the results of these predictions are both quantitative and qualitative, only qualitative verification has been obtained thus far, such as visual observation of wrinkled conducting plies discovered in unwrapped capacitors. The purpose of this paper is to describe two experimental activities that were undertaken to support the analytical modeling effort and provide quantitative, experimental verification of some of the analysis predictions.
The technical issues brought about by recent federal mandates are reviewed and discussed. Progress made in the elimination of CFCs is briefly reviewed. The problems, implications, and status of pending anti-lead legislation and taxation are discussed at length. Recommendations are made for the enactment of rational, fair, and orderly legislation and taxation.
This paper describes current research and development on a miniaturized sensing system for use during in situ characterization of nuclear waste storage tanks. Sandia is designing this sensing system as a tool for a large robotic arm that is deployed through an access port in the top of a storage tank. While the robot arm scans the sensing package over the waste, a distributed computing system acquires sensor data, correlates the data with the position of the robot, and produces maps of the chemical and radiological contents of the tanks in real time. We have built and demonstrated a first prototype system containing eight sensors. 53 refs.
Two revisions of the CONTAIN code, CONTAIN 1.11 and 1.12 , have recently been released. The purpose of this paper is to highlight the new features of these revisions and to discuss other new code features currently under development. The features of CONTAIN 1.11 discussed here include a quasi-mechanistic concrete outgassing model, the connected structure option for heat conduction between compartments, and a new approach for modeling forced convective heat transfer. The direct containment heating (DCH) models released as part of CONTAIN 1.12 are also discussed. New code features currently under development include a revised gas combustion model and a new multifield DCH model. New features of the revised combustion model include the treatment of spontaneous recombination and diffusion flames. CONTAIN plant calculations comparing the old and the revised combustion models are presented. The new features of the multifield DCH model are discussed, and demonstration calculations using this model to analyze a small scale experiment are presented.
A previous investigation of laser-induced damage mechanisms and corresponding thresholds in step-index, multimode fibers was motivated by an interest in optical systems for firing explosives. In the initial study, the output from a compact, multimode Nd/YAG laser was coupled into fiber cores of pure fused silica. End-face polishing steps were varied between successive fiber lots to produce improved finishes, and each fiber was subjected to a sequence of progressively increasing energy densities up to a value more than 80 J/cm{sup 2}. Essentially all of the tested fibers experienced a ``laser conditioning`` process at the front fiber face, in which a visible plasma was generated for one or more laser shots. Rather than produce progressive damage at the front surface, however, this process would eventually cease and leave the surface with improved damage resistance. Once past this conditioning process, the majority of fibers damaged at the rear end face. Other modes of damage were observed either at locations of fixturing stresses or at a location of high static tensile stress resulting from bends introduced to the fiber. The current experiments were conducted with a new laser having a shorter pulsewidth and a significantly different mode structure. The beam was injected into the fiber using a geometry that had been successful in the previous study in minimizing a damage mechanism which can occur at the core/cladding interface within the first few hundred fiber diameters. However, the different mode structure of the new laser apparently resulted in this mechanism dominating the current results.
The Department of Energy`s (DOE`s) Office of Civilian Radioactive Waste Management (OCRWM) is in the process of developing a new generation of casks to transport spent fuel from commercial nuclear reactor facilities to federal waste facilities. In evaluating the needs of the cask development program a number of unresolved technical issues with potential impacts on the transportation system were identified. This paper provides three samples of issues being addressed by the Cask Systems Development Program for technical resolution: (1) burn-up credit, (2) containment source term evaluation, and (3) weeping.
SMILE is a coaxial Self Magnetically Insulated Transmission Line voltage adder. It replaces the original beam line of the RADLAC II accelerator by a 12.5 m long cathode electrode. The anode electrode remains practically the same, consisting of the original eight insulating stacks or feeds which are connected with equal diameter stainless steel cylinders. The beam is produced at the end of the accelerator and is free of all the possible instabilities associated with accelerating gaps and magnetic vacuum transport. Annular beams with {beta}{perpendicular} {le} 0.1 and radius r{sub b} {le} 1 cm were routinely obtained and extracted from a small magnetically-immersed foilless electron diode. Results of the experimental evaluation are presented and compared with design parameters and numerical simulation predictions. 4 refs.
In this paper, measurements on the quasi-isentropic compression of tungsten to stress levels of 250 GPa are reported. Results of these experiments have been compared to those obtained under shock loading conditions to comparable stresses. These experiments have allowed the determination of temperature, pressure, and loading rate effects on the dynamic yield strength of tungsten up to 250 GPa. These results show that the dynamic yield strength of tungsten is dependent on the loading rate with the strength being higher for the relatively slower rates of loading along the quasi-isentropic. The pressure dependence of the yield strength of tungsten is determined nearly independent of temperature effects from quasi-isentropic loading experiments to 250 GPa, because the temperature rise in an quasi-loading experiment is much lower than those associated with shock loading experiments.
Continuum dynamics codes are categorized as Lagrangian or Eulerian according to the motion of the mesh. A Lagrangian code`s mesh moves with the material, so no mass flows between cells. An Eulerian code`s mesh is stationary, so mass flows between the cells. Eulerian codes have improved to the point where they are routinely used to solve a broad variety of large deformation solid and fluid dynamics problems ranging from air flow over an airplane wing to meteor impact on space structures. This presentation will concentrate on multi-fluid Eulerian codes capable of modeling transient were propagation in solids. These codes use a two-step process to integrate the physics across a time step. The first step, referred to as the Lagrangian step, integrates the physics on a Lagrangian mesh across the time step. The field values are then at the new time, but they are on the distorted Lagrangian mesh. The second step, referred to as the remap step, remaps the data on the distorted Lagrangian mesh back to the original Eulerian mesh thus completing one time step. The algorithms used in the first step are similar to those used in modern Lagrangian codes but they must be extended to handle multi-material cells. The algorithms used in the second step are complex and must be very carefully chosen to minimize errors. These algorithms include second-order, monotone advection equations to calculate the quantities flowing between cells. They also require algorithms that construct material interfaces inside multi-material cells. The strength and limitations of currently used numerical techniques will be discussed. New code development activities that combine the best features on both Lagrangian and Elueian codes will also be discussed. These new codes will employ the strengths of both technologies to address problems that cannot be adequately solved at this time.
The Hybrid Thin-Slot Algorithm (HTSA) integrates a transient integral-equation solution for an aperture in an infinite plane into a finite-difference time-domain (FDTD) code. The technique was introduced for linear apertures and was extended to include wall loss and lossy internal gaskets. A general implementation for arbitrary thin slots is briefly described here. The 3-D FDTD-code TSAR was selected for the implementation. The HTSA does not provide universal solutions to the narrow slot problem, but has merits appropriate for particular applications. The HTSA is restricted to planar slots, but can solve the important case that both the width and depth of the slot are narrow compared to the FDTD spatial cell. IN addition, the HTSA is not bound to the FDTD discrete spatial and time increments, and therefore, high-resolution solutions for the slot physics are possible. The implementation of the HTSA into TSAR is based upon a ``slot data file`` that includes the cell indices where the desired slots are exist within the FDTD mesh. For an HTSA-defined slot, the wall region local to the slot is shorted, and therefore, to change the slot`s topology simply requires altering the file to include the desired cells. 7 refs.
The one-electron energy levels of icosahedral boron clusters have been calculated as a function of intericosahedral spacing maintaining the intraicosahedral spacing of {alpha}-boron. For crystalline lattice constants greater than 1.25 times the equilibrium one, band overlap occurs with concomitant metallic behavior. At smaller lattice constants, orbitals(bands) associated with bonds to adjacent icosahedra are lowered and orbitals(bands) associated with ``antibonds`` are raised. Four bands which were three quarters full become empty, while three bands which were empty become filled. This leads to an energy gap between the filled states and the empty states which accounts for the experimentally observed insulating behavior of this elemental material with three valence electrons per atom.
Verifying the velocity accuracy of a GPS receiver or an integrated GPS/INS system in a dynamic environment is a difficult proposition when many of the commonly used reference systems have velocity uncertainities of the same order of magnitude or greater than the GPS system. The results of flight tests aboard an aircraft in which multiple reference systems simultaneously collected data to evaluate the accuracy of an integrated GPS/INS system are reported. Emphasis is placed on obtaining high accuracy estimates of the velocity error of the integrated system in order to verify that velocity accuracy is maintained during both linear and circular trajectories. Three different reference systems operating in parallel during flight tests are used to independently determine the position and velocity of an aircraft in flight. They are a transponder/interrogator ranging system, a laser tracker, and GPS carrier phase processing. Results obtained from these reference systems are compared against each other and against an integrated real time differential based GPS/INS system to arrive at a set of conclusions about the accuracy of the integrated system.
Computer-aided molecular design methods were used to tailor binding sites for small substrate molecules, including CO{sub 2} and methane. The goal is to design a cavity, adjacent to a catalytic metal center, into which the substrate will selectively bind through only non-bonding interactions with the groups lining the binding pocket. Porphyrins are used as a basic molecular structure, with various substituents added to construct the binding pocket. The conformations of these highly-substituted porphyrins are predicted using molecular mechanics calculations with a force field that gives accurate predictions for metalloporhyrins. Dynamics and energy-minimization calculations of substrate molecules bound to the cavity indicate high substrate binding affinity. The size, shape and charge-distribution of groups surrounding the cavity provide molecular selectivity. Specifically, calculated binding energies of methane, benzene, dichloromethane, CO{sub 2} and chloroform vary by about 10 kcal/mol for metal octaethyl-tetraphenylporphyrins (OETPPs) with chloroform, dichloromethane, and CO{sub 2} having the lowest. Significantly, a solvent molecule is found in the cavity in the X-ray structures of Co- and CuOETPP crystals obtained from dichloromethane. 5 refs., 3 figs., 3 tabs.
Single Event Upset Imaging utilizes the scanning of a micro-focused MeV ion beams across an integrated circuit to test the upset response of the circuit to energetic heavy ions. Using this technique, the position dependence of logic state upsets, as well as the charge collection efficiency of an integrated circuit, can be directly measured with micron resolution. We present in this paper a review of a series of measurements carried out on the TA670 16K static random access memory chip which display this technique`s capabilities.
Hot cracking, or solidification cracking, is one of the most extensively studied phenomenon in welding metallurgy. The efforts made to identify the causes of this type of cracking have been driven by the negative commercial and engineering consequences resulting from the formation of these defects. Through judicious weld joint design, the mechanical restraint can be minimized, but it can never be entirely eliminated simply because metals expand and contract when heated and cooled, respectively. The localized nature of heat input in fusion welding insures a non-homogeneous thermal field being applied to the parts being welded, resulting in the development of strains in the as-solidifying weld metal. With the inherent limitations on the mechanical restraint factor, much research has gone into identifying those alloy compositions which minimize the microstructural factor required for hot cracking to occur. Examples from the author`s own research are presented as a tutorial to show how differential thermal analysis techniques have been used to study the chemical/microstructural factors associated with solidification and fusion zone hot cracking in nickel based engineering alloys. References to other uses of these techniques in related welding metallurgy studies are also given.
Dislocation formation in InAs{sub 1-x}Sb{sub x} buffer layers grown by metal-organic chemical vapor deposition is shown to be reproducibly enhanced by p-type doping at levels greater than or equal to the intrinsic carrier concentration at the growth temperature. To achieve a carrier concentration greater than 2 {times} 10{sup 18} cm{sup {minus}3}, the intrinsic carrier concentration of InSb at 475 C, p-type doping with diethylzinc was used. Carrier concentrations up to 6 {times} 10{sup 18} cm{sup {minus}3} were obtained. The zinc doped buffer layers have proven to be reproducibly crack free for InAs{sub 1-x}Sb{sub x} step graded buffer layers with a final composition of x = 0.12 and a strained layer superlattice with an average composition of x = 0.09. These buffer layers have been used to prepare SLS infrared photodiodes. The details of the buffer layer growth, an explanation for the observed Fermi level effect and the growth and characterization of an infrared photodiode are discussed.
The use of coatings on carbon-carbon materials to reduce the oxidation of carbon is of interest for the production of non-ablative aerospace structures. The arc-jet ground test facility can produce the high energy oxidizing environment necessary to simulate hypersonic flight in which to test candidate coatings. The test conditions usually required are characterized by material temperature and length of time the material remains at that temperature. Material specimens were exposed to high energy supersonic air exhausting from the NASA-Ames Research Center`s 20-MW arc-jet facility. The carbon-carbon materials were heated to required temperatures with arc-heated air for specified lengths of time. This report describes the test methodology and observations of those tests.
We described a new family of versatile, cascadable, optical switches with different functional characteristics -- latching, non-latching, and bistable -- using a single epitaxial structure base don the monolithic integration of photothyristors and surface-emitting layers. High performance optical switching characteristics have been achieved for all three switch archetypes. We also demonstrate the AND, OR, NAND, NOR, and INVERT optical logic functions using monolithic switch structures. 7 refs.
A boundary integral equation method for steady unsaturated flow in nonhomogeneous porous media is presented. Steady unsaturated flow in porous media is described by the steady form of the so-called Richards equation, a highly nonlinear Fokker-Planck equation. By applying a Kirchhoff transformation and employing an exponential model for the relation between capillary pressure and hydraulic conductivity, the flow equation is rendered linear in each subdomain of a piece-wise homogeneous material. Unfortunately, the transformation results in nonlinear conditions along material interfaces, giving rise to a jump in the potential along these boundaries. An algorithm developed to solve the nonhomogeneous flow problem is described and verified by comparison to analytical and numerical solutions. The code is applied to examine the moisture distribution in a layered porous medium due to infiltration from a strip source, a model for infiltration from shallow ponds and washes in arid regions.
Structural system identification is undergoing a period of renewed interest. Probabilistic approaches to physical parameter identification in analysis finite element models make uncertainty in test results an important issue. In this paper, we investigate this issue with a simple, though in many ways representative, structural system. The results of two modal parameter identification techniques are compared and uncertainty estimates, both through bias and random errors, are quantified. The importance of the interaction between test and analysis is also highlighted. 25 refs.
Pre-exposure induced stress corrosion cracking (SCC) of an Al-Li-Cu, AA 2090, was studied using a variety of test techniques. Results from SCC testing in a simulated isolated pit solution are correlated with electrochemical corrosion rate data obtained for individual phases in the subgrain boundary region. These experimental data, combined with existing data on the crevice chemistry of isolated pits in Al-Li alloys and X-ray diffraction studies of solid corrosion products formed in crevice environments are used to propose a model for pre-exposure induced cracking based on anodic dissolution along subgrain boundaries. Key features of the model are selective dissolution of the subgrain boundary T{sub 1} phase (Al{sub 2}CuLi) at the crack tip and passivation of crack walls by the formation of an Li{sub 2}[Al{sub 2}(OH){sub 6}]{sub 2}{center_dot}CO{sub 3}{center_dot}nH{sub 2}O barrier film.
The transportation risk evaluation code RADTRAN 4 is designed to evaluate doses and risks associated with the transportation of radioactive materials (Ne92). RADTRAN 4 may be used to calculate dose consequences for incident-free transportation and dose risks for accidents. Consequences of normal (or incident-free) transportation include doses to crew members, persons at stops, and members of the public sharing a route segment (on-link) and residing near the segment (off-link) during normal transportation. These dose estimates are not multiplied by a probability factor and, hence, are referred to as dose consequences. Calculated doses that might be incurred during accidents are multiplied by the probabilities of those accidents, and hence are referred to as dose risks. RADTRAN 4 includes a LINK option that allows the user to characterize each link or segment of a transportation route in greater detail than that provided by average or default values for route-related parameters.
This paper explains how an induction coilgun works and presents the factors which go into its design. Our purpose is to obtain algebraic expressions which, although crude, provide useful predictors of behavior, illustrate the dependence on various parameters, and suggest ways to optimize the design. Detailed prediction of the gun`s behavior can be obtained from simulation codes, such as SLINGSHOT.
Very high driving pressures (tens or hundreds of GPa), are required to accelerate flier plats to hypervelocities. This loading pressure pulse on the fiber plates must be nearly shockless to prevent the plate from melting or vaporizing. This is accomplished by using graded-density impactors referred to as ``pillows.`` When this graded-density material is used to impact a flier-plate in a modified two-stage light gas gun, nearly shockless megabar pressures are introduced into the flier plate. The pressure pulses must also be tailored to prevent spallation of the flier-plate. This technique has been used to launch nominally 1-mm-thick aluminum, magnesium and titanium (gram-size) intact plates to 10.4 km/s, and 0.5-mm-thick aluminum and titanium (half-gram size) intact plates to 12.2 km/s. This is the highest mass-velocity capability attained with laboratory launchers to data, and should open up new regimes of impact physics and lethality studies related to space sciences for laboratory investigations. 14 refs.
Fourier transform-infrared spectroscopy (FT-IR) was used to investigate the adsorption and thermally-induced decomposition of copper (I) {beta}-diketonate precursors of the type (hfac)CuL, where hfac is the hexafluoroacetylacetonate bidentate ligand and L is trimethylphosphine or 1,5-cyclooctadiene. The (hfac)CuPMe{sub 3} precursor desorbs from the surface at very low temperatures whereas the (hfac)Cu(1,5-COD) dissociates on adsorption, liberating 1,5-COD and leaving a surface(hfac)Cu complex which can subsequently disproportionate. Evidence is provided for hydrogen-bonding between the hfac ligand and the surface silanols for (hfac)CuPMe{sub 3}, but not for (hfac)Cu(1,5-COD). These results are consistent with the selective behavior of these precursors for copper deposition and suggest that the selectivity of the (hfac)CuPMe{sub 3} and (hfac)Cu(1, 5-COD) precursors may be due to the ability of the hfac ligand to hydrogen bond to the surface silanol groups.
The concept of allowing reactivity credit for the transmuted state of spent fuel offers both economic and risk incentives. This paper presents a general overview of the technical work being performed in support of the US Department of Energy (DOE) program to resolve issues related to the implementation of burnup credit. An analysis methodology is presented along with information representing the validation of the method against available experimental data. The experimental data that are applicable to burnup credit include chemical assay data for the validation of the isotopic prediction models, fresh fuel critical experiments for the validation of criticality calculations for various casks geometries, and reactor restart critical data to validate criticality calculations with spent fuel. The methodology has been specifically developed to be simple and generally applicable, therefore giving rise to uncertainties or sensitivities which are identified and quantified in terms of a percent bias in k{sub eff}. Implementation issues affecting licensing requirements and operational procedures are discussed briefly.
The US Department of Energy is sponsoring a research effort through Sandia National Laboratories and the University of Missour-Rolla to test a correlation for the upper shelf energy (USE) values obtained from the impact testing of subsize Charpy V-notch specimens to those obtained from the testing of full size samples. The program involves the impact testing of unirradiated and irradiated full, half, and third size Charpy V-notch specimens. To verify the applicability of the correlation on LWR materials unirradiated and irradiated full, half, and third size Charpy V-notch specimens of a commercial pressure vessel steel (ASTM A533 Grade B) will be tested. This paper will provide details of the program and present results obtained from the application of the developed correlation methodology to the impact testing of the unirradiated full, half, and third size A533 Grade B Charpy V-notch specimens.
Relativistic high current electron beams can be transported long distances across the geomagnetic field using the IFR (Ion focused Regime) technique. IFR is a method of providing strong electrostatic focusing and guiding of the beam. The guiding is sufficiently strong to allow the beam to transport any angle with respect to geomagnetic field. In the IFR method, first an ionizing laser (or any ionizing method) is used to create a preionized cylindrical channel.
We present a learning algorithm designed to improve robot path planning. The algorithm relies on an existing path planner to provide solutions to difficult tasks. From these solutions, it learns a sparse network of useful robot subgoals which guide and support fast planning. We analyze the algorithm theoretically by developing some general techniques useful in characterizing behaviors of probabilistic learning. We also demonstrate the effectiveness of the algorithm empirically with an existing path planner in practical environments. The learning algorithm not only reduces the time cost of existing planners, but also increases their capability in solving difficult tasks. 7 refs.
An understanding of the state of stress on faults is important for pre- and postclosure performance considerations for the potential high-level radioactive waste repository at Yucca Mountain. This paper presents the results of three-dimensional numerical analyses that provide estimates of the state of stress through time (10,000 years) along three major faults in the vicinity of the potential repository due to thermal stresses resulting from waste emplacement. It was found, that the safety factor for slip close to the potential repository increases with time after waste emplacement. Possible fault slip is predicted above and below the potential repository for certain loading conditions and times. In general, thermal loading reduces the potential for slip in the vicinity of the potential repository.
This paper presents a summary of the conduct and findings of the Exploratory Studies Facility Alternatives Study (ESF-AS). The Exploratory Studies Facility (ESF) is being planned for use in the characterization of a site for a potential high-level nuclear waste repository at Yucca Mountain, NV. The purpose of the ESF-AS were to identify and rank order ESF-repository options and to improve understanding of the favorable or unfavorable features of the ESF design. The analysis resulted in the ranking of 34 options, in accordance with the extent to which each option could achieve the objectives. Additional findings regarding design features that were identified as key elements in an option`s ability to provide good overall performance are also discussed.
Excavation stability in an underground nuclear waste repository is required during construction, emplacement, retrieval (if required), and closure phases to ensure worker health and safety, and to prevent development of potential pathways for radionuclide migration in the post-closure period. Stable excavations are developed by appropriate excavation procedures, design of the room shape, design and installation of rock support reinforcement systems, and implementation of appropriate monitoring and maintenance programs. In addition to the loads imposed by the in situ stress field, the repository drifts will be impacted by thermal loads developed after waste emplacement and, periodically, by seismic loads from naturally occurring earthquakes and underground nuclear events. A priori evaluation of stability is required for design of the ground support system, to confirm that the thermal loads are reasonable, and to support the license application process. In this report, a design methodology for assessing drift stability is presented. This is based on site conditions, together with empirical and analytical methods. Analytical numerical methods are emphasized at this time because empirical data are unavailable for excavations in welded tuff either at elevated temperatures or under seismic loads. The analytical methodology incorporates analysis of rock masses that are systematically jointed, randomly jointed, and sparsely jointed. In situ thermal and seismic loads are considered. Methods of evaluating the analytical results and estimating ground support requirements for all the full range of expected ground conditions are outlines. The results of a preliminary application of the methodology using the limited available data are presented. 26 figs., 55 tabs.
The Yucca Mountain Site Characterization Project is studying Yucca Mountain in southwestern Nevada as a potential site for a high-level nuclear waste repository. Site characterization includes surface-based and underground testing. Analyses have been performed to design site characterization activities with minimal impact on the ability of the site to isolate waste, and on tests performed as part of the characterization process. One activity of site characterization is the construction of an Exploratory Studies Facility, for which many design options are being considered, including shafts, drifts, and ramps. The information in this report pertains to: (1) engineering calculations of the potential distribution of residual water from constructing the shafts and drifts; (2) numerical calculations predicting the movement of residual construction water from the shaft and drift walls into the rock; and (3) numerical calculations of the movement of residual water and how the movement is affected by ventilation. This document contains information that has been used in preparing Appendix 1 of the Exploratory Studies Facility Design Requirements document for the Yucca Mountain Project.
Numerical results are presented for the Performance Assessment Calculational Exercise (PACE-90). One- and two-dimensional water and solute transport are presented for steady infiltration into Yucca Mountain. Evenly distributed infiltration rates of 0.01, 0.1, and 0.5 mm/yr were considered. The calculations of solute transport show that significant amounts of radionuclides can reach the water table over 100,000 yr at the 0.5 mm/yr rate. For time periods less than 10,000 yr or infiltrations less than 0.1 mm/yr very little solute reaches the water table. The numerical simulations clearly demonstrate that multi-dimensional effects can result in significant decreases in the travel time of solute through the modeled domain. Dual continuum effects are shown to be negligible for the low steady state fluxes considered. However, material heterogeneities may cause local amplification of the flux level in multi-dimensional flows. These higher flux levels may then require modeling of a dual continuum porous medium.
In support of the development of American National Standards Institute standards for the transport of radioactive materials, Sandia has a program to characterize the normal transport environment. This program includes both analytical modeling of package and trailer responses, and over-the-road tests to measure those responses. This paper presents the results of a series of over-the-road tests performed using Chem-Nuclear equipment in the Barnwell, SC, area. The test events included a variety of road types such as rough concrete, shock events such as railroad grade crossings, and driver responses such as sharp turns. The response of the package and trailer to these events was measured with accelerometers at various locations to determine the inertial loads. Either load cells or strain gages were used to measure tiedown response. These accelerations and loads were measured on systems with flexible and ``rigid`` tiedowns. The results indicated that while significant accelerations occur on the trailer bed, these do not translate into equivalent loads in either the package or the tiedown system. This indicates that trailer-bed response should not be used in determining the load factor for fatigue calculations of the package components or in determining design loads for tiedowns.
Currently, there are several Greater Confinement Disposal (GCD) boreholes at the Radioactive Waste Management Site (RWMS) for the Nevada Test Site. These are intermediate-depth boreholes used for the disposal of special case wastes, that is, radioactive waste within the Department of Energy complex that do not meet the criteria established for disposal of high-level waste, transuranic waste, or low-level waste. A performance assessment is needed to evaluate the safety of the GCD site, and to examine the feasibility of the GCD disposal concept as a disposal solution for special case wastes in general. This report documents the effort in defining all the waste inventory presently disposed of at the GCD site, and the inventory and release model to be used in a performance assessment for compliance with the Environmental Protection Agency`s 40 CFR 191.
The Faceted Stretched-Membrane Dish Program is part of a DOE-sponsored effort to develop a commercial 25 kWe dish/Stirling system employing a twelve-facet dish concentrator. The facets will utilize the stretched-membrane technology originated in the heliostat development program. Each facet is constructed with a thin metal membrane stretched over both sides of a steel ring. When a small vacuum is induced between the membranes they assume a parabolic contour capable of concentrating sunlight at a predetermined focal length. A reflective polymer film is attached to the face of the facet of the facet to enhance the optical performance. During Phase II of the Faceted Stretched-Membrane Dish Program, Science Applications International Corp. and Solar Kinetics, Inc., constructed prototype 3.5-meter facets utilizing different design approaches to demonstrate their manufacturability and optical performance. Sandia engaged in a program to determine the on-sun performance of the facets (for f/Ds of 2.7 to 3.0). A uniformly distributed slope error was used as the basis for comparison. Flux arrays based on slope error from a computer model were compared to a measured flux array for each facet. The slope error for the facet was determined by the value that would produce a modeled array with the minimum mean square difference to the measured array. The facet produced by SAIC demonstrated uniform slope errors of 2.2 to 3.0 milliradians with peak flux intesities of 334 to 416 kW/m{sup 2}. The SKI facet had slope errors of 1.6 to 1.9 milliradians with peak flux intesities of 543 to 1186 kW/m{sup 2}.
A 1-MeV neutron damage equivalence methodology and damage function have been developed for GaAs based on a recoil-energy dependent damage efficiency and the displacement kerma. This method, developed using life-time degradation in GaAs LEDs in a variety of neutron spectra, is also shown to be applicable to carrier removal. A validated methodology, such as this, is required to ensure and evaluate simulation fidelity in the neutron testing of GaAs semiconductors.
This report describes Welch's method for computing Power Spectral Densities (PSDs). We first describe the bandpass filter method which uses filtering, squaring, and averaging operations to estimate a PSD. Second, we delineate the relationship of Welch's method to the bandpass filter method. Third, the frequency domain signal-to-noise ratio for a sine wave in white noise is derived. This derivation includes the computation of the noise floor due to quantization noise. The signal-to-noise ratio and noise flood depend on the FFT length and window. Fourth, the variance the Welch's PSD is discussed via chi-square random variables and degrees of freedom. This report contains many examples, figures and tables to illustrate the concepts. 26 refs.
Four expert-judgment teams have developed analyses delineating possible future societies in the next 10,000 years in the vicinity of the Waste Isolation Pilot Plant (WIPP). Expert-judgment analysis was used to address the question of future societies because neither experimentation, observation, nor modeling can resolve such uncertainties. Each of the four, four-member teams, comprised of individuals with expertise in the physical, social, or political sciences, developed detailed qualitative assessments of possible future societies. These assessments include detailed discussions of the underlying physical and societal factors that would influence society and the likely modes of human-intrusion at the WIPP, as well as the probabilities of intrusion. Technological development, population growth, economic development, conservation of information, persistence of government control, and mitigation of danger from nuclear waste were the factors the teams believed to be most important. Likely modes of human-intrusion were categorized as excavation, disposal/storage, tunneling, drilling, and offsite activities. Each team also developed quantitative assessments by providing probabilities of various alternative futures, of inadvertent human intrusion, and in some cases, of particular modes of intrusion. The information created throughout this study will be used in conjunction with other types of information, including experimental data, calculations from physical principles and computer models, and perhaps other judgments, as input to performance assessment.'' The more qualitative results of this study will be used as input to another expert panel considering markers to deter inadvertent human intrusion at the WIPP.
A control algorithm is proposed for a molten-salt solar central receiver in a cylindrical configuration. The algorithm simultaneously regulates the receiver outlet temperature and limits thermal-fatigue damage of the receiver tubes to acceptable levels. The algorithm is similar to one that was successfully tested for a receiver in a cavity configuration at the Central Receiver Test Facility in 1988. Due to the differences in the way solar flux is introduced on the receivers during cloud-induced transients, the cylindrical receiver will be somewhat more difficult to control than the cavity receiver. However, simulations of a proposed cylindrical receiver at the Solar Two power plant have indicated that automatic control during severe cloud transients is feasible. This paper also provides important insights regarding receiver design and lifetime as well as a strategy for reducing the power consumed by the molten-salt pumps. 14 refs., 7 figs., 2 tabs.
This paper summarizes the results of aging, condition monitoring, and accident testing of Class 1E cables used in nuclear power generating stations. Three sets of cables were aged for up to 9 months under simultaneous thermal ({approx_equal} 100{degrees}C) and radiation ({approx_equal}0.10 kGy/hr) conditions. After the aging, the cables were exposed to a simulated accident consisting of high dose rate irradiation ({approx_equal}6 kGy/hr) followed by a high temperature steam exposure. A fourth set of cables, which were unaged, were also exposed to the accident conditions. The cables that were aged for 3 months and then accident tested were subsequently exposed to a high temperature steam fragility test (up to 400{degrees}C), while the cables that were aged for 6 months and then accident tested were subsequently exposed to a 1000-hour submergence test in a chemical solution. The results of the tests indicate that the feasibility of life extension of many popular nuclear power plant cable products is promising and that mechanical measurements (primarily elongation, modulus, and density) were more effective than electrical measurements for monitoring age-related degradation. In the high temperature steam test, ethylene propylene rubber (EPR) cable materials generally survived to higher temperatures than crosslinked polyolefin (XLPO) cable materials. In dielectric testing after the submergence testing, the XLPO materials performed better than the EPR materials. This paper presents some recent experimental data that are not yet available elsewhere and a summary of findings from the entire experimental program.
Reflux solar receivers for dish-Stirling electric power generation systems are currently being investigated by several companies and laboratories. In support of these efforts, the AEETES thermal performance numerical model has been developed to predict thermal performance of pool-boiler and heat-pipe reflux receivers. The formulation of the AEETES numerical model, which is applicable to axisymmetric geometries with asymmetric incident fluxes, is presented in detail. Thermal efficiency predictions agree to within 4.1% with test data from on-sun tests of a pool-boiler reflux receiver. Predicted absorber and sidewall temperatures agree with thermocouple data to within 3.3.% and 7.3%, respectively. The importance of accounting for the asymmetric incident fluxes is demonstrated in comparisons with predictions using azimuthally averaged variables. The predicted receiver heat losses are characterized in terms of convective, solar and infrared radiative, and conductive heat transfer mechanisms. 27 refs., 9 figs., 4 tabs.
Combustion of energetic materials involves processes in both gas and condensed phases and is governed by coupled thermal, physical, and chemical phenomena. Development of reliable models for design, performance, stability, and hazard analyses requires detailed understanding of three general chemical reaction regimes: (1) initial condensed-phase decomposition, (2) subsequent interaction of decomposition products with the remaining condensed phase, and (3) gas-phase reaction of decomposition products to form the ultimate combustion products. The first two regimes are the least understood and most difficult to study, particularly the initial condensed-phase decomposition. The basic difficulty in studying condensed phase phenomena has been the inability to probe directly chemistry in the condensed phase under isothermal condition and with the spatial and temporal resolution needed at higher temperatures and reaction rates. Thin-film samples provide a means to study condensed-phase chemistry at isothermal conditions and with microsecond temporal resolution. We are developing an experiment system that employs rapidly heated thin- film samples and multiple diagnostics to examine condensed-phase chemistry and monitor evolved gas species. Results from our initial work have been encouraging. Thin-film samples of several energetic materials have been prepared and appear to be representative of bulk materials. Furthermore, preliminary experiments indicate that all the use of these samples with two chemical diagnostic techniques, time-of- flight mass spectrometry (TOFMS) and time-resolved infrared spectral photography (TRISP), is viable. 5 refs., 8 figs.
We are studying the kinetics of singlet oxygen ({sup 1}{Delta}{sub g}O{sub 2}) in solid polymers by monitoring its phosphorescence in time-resolved experiments. In macromolecular matrices where {sup 1}{Delta}{sub g}O{sub 2} is produced by energy transfer from a photosensitizer, {sup 1}{Delta}{sub g}O{sub 2} lifetimes can be obtained by deconvoluting the {sup 1}{Delta}{sub g}O{sub 2} sensitizer kinetics from the {sup 1}{Delta}{sub g}O{sub 2} phosphorescence signal. The sensitizer kinetics can be obtained in a flash absorption experiment. These time-resolved techniques have been utilized to examine the interaction of {sup 1}{Delta}{sub g}O{sub 2} in polymers with two types of additives: (1) molecules capable of undergoing chemical reactions with {sup 1}{Delta}{sub g}O{sub 2} (reactive quenchers) and (2) molecules capable of quenching {sup 1}{Delta}{sub g}O{sub 2} to its ground triplet state (physical quenchers). From this study we have determined directly that significant reactive and physical quenching of {sup 1}{Delta}{sub g}O{sub 2} are possible in a solid polymer. The polymer matrix greatly reduces the quenching rate of a very efficient quencher and slightly elevates the quenching rate of inefficient quenchers, as compared with rates determined in analogous liquids. This compressed range of quenching efficiencies has implications for understanding photodegradation and stabilization of polymers. 12 refs., 3 figs., 1 tab.
American Society of Mechanical Engineers, Applied Mechanics Division, AMD
Frear, D.R.; Jones, W.B.; Morris Jr., J.W.; Mei, Z.
The eutectic Sn-Pb solder alloy is discussed with respect to alloy development options to improve the thermomechanical fatigue behavior of solder joints. Eutectic Sn-Pb solder joints fail through the development of a heterogeneous coarsened band of recrystallized and coarsened Pb- and Sn-rich phases. All imposed deformation concentrates solely into this thin region, accelerating fatigue failures. The development of solder alloys is currently being undertaken to improve the fatigue characteristics of eutectic Sn-Pb solder. New alloys must retain wetting and manufacturability characteristics similar to eutectic Sn-Pb. The options discussed to improve fatigue life include: creating a fine superplastic microstructure, small alloy additions to homogenize the microstructure, carbon reinforced composite solder, dispersed second phase precipitates that break up the solder microstructure, and using different solder alloys to replace eutectic Sn-Pb.
The polarimetry problem (the measurement of the radar-cross-section polarization scattering matrix) is described. Two methods of calibrating a polarimetric radar are outlined. The first is a general multiple-calibration-target (MCT) method applicable to almost any radar system. The second is a simple, single-calibration-target (SCT) method applicable to systems which use a single antenna for both transmit/receive and a reciprocal RF network. The performance of the MCT method is examined through the use of Monte Carlo simulations. Finally, the SCT method is applied to measurements from the SCATTER facility, demonstrating about 40 dB isolation between polarization components in the frequency domain and in excess of 50 dB in the range domain.