Paramount to the modeling of unsaturated flow and transport through fractured porous media is a clear understanding of the processes controlling fracture-matrix interaction. As a first step toward such an understanding, two preliminary experiments have been performed to investigate the influence of matrix imbibition on water percolation through unsaturated fractures in the plane normal to the fracture. Test systems consisted of thin slabs of either tuff or an analog material cut by a single vertical fracture into which a constant fluid flux was introduced. Transient moisture content and solute concentration fields were imaged by means of x-ray absorption. Flow fields associated with the two different media were significantly different owing to differences in material properties relative to the imposed flux. Richards` equation was found to be a valid means of modeling the imbibition of water into the tuff matrix from a saturated fracture for the current experiment.
A set of detailed geostatistical simulations of porosity has been produced for a layered stratigraphic sequence of welded and nonwelded volcanic tuffs at Yucca Mountain, Nevada. The simulations are produced using a composite. model of spatial continuity and they are highly conditioned to abundant drill hole (core) information. A set of derivative simulations of saturated hydraulic conductivity has been produced, in the absence of conditioning data, using a cross-variable relationship developed from similar data elsewhere. The detailed simulations reproduce both the major stratigraphic units and finer scale layering indicated by the drill hole data. These simulations have been scaled up several order of magnitude to represent block-scale effective hydrologic properties suitable for use in numerical modeling of groundwater flow and transport. The upscaling process involves the reformulation of a previously reported method that iteratively adapts an initial arbitrary grid to ``homogenize`` the detailed hydraulic properties contained within the adjusted cell limits and to minimize the size of cell in highly heterogeneous regions. Although the computation of the block-effective property involves simple numerical averaging, the blocks over which these averages are computed are relatively homogeneous, which reduces the numerical difficulties involved in averaging non-additive properties, such as permeability. The entire process of simulation and upscaling is rapid and computationally efficient compared with alterative techniques. It is thus suitable for the Monte Carlo evaluation of the uncertainty in site characterization as it affects the results of groundwater flow and transport calculations.
Hydrologic properties have been measured on outcrop samples taken from a detailed, two-dimension grid covering a 1.4 km outcrop exposure of the 10-m thick non-welded-to-welded, shardy base microstratigraphic unit of the Tiva Canyon Member of the Miocene Paintbrush Tuff at Yucca Mountain, Nevada. These data allow quantification of spatial trends in rock matrix properties that exist in this important hydrologic unit. Geologic investigation, combined with statistical and geostatistical analyses of the numerical data, indicates that spatial variability of matrix properties is related to deterministic geologic processes that operated throughout the region. Linear vertical trends in hydrologic properties are strongly developed in the shardy base microstratigraphic unit, and they are more accurately modeled using the concept of a thickness-normalized stratigraphic elevation within the unit, rather than absolute elevation. Hydrologic properties appear to be correlated over distances of 0.25 to 0.3 of the unit thickness after removing the deterministic vertical trend. The use of stratigraphic elevation allows scaling of identified trends by unit thickness which may be of particular importance in a basal, topography-blanketing unit such as this one. Horizontal changes in hydrologic properties do not appear to form obvious trends within the limited lateral geographic extent of the ash-flow environment that was examined. Matrix properties appear to be correlated horizontally over distances between 100 and 400 m. The existence and quantitative description of these trends and patterns of vertical spatial continuity should increase confidence in models of hydrologic properties and groundwater flow in this area that may be constructed to support the design of a potential high-level nuclear waste repository at Yucca Mountain.
This paper presents a method of estimating the rock mass properties for the welded and nonwelded tuffs based on currently available information on intact rock and joint characteristics at the Yucca Mountain site. Variability of the expected ground conditions at the potential repository horizon (the TSw2 thermomechanical unit) and in the Calico Hills nonwelded tuffs is accommodated by defining five rock mass quality categories in each unit based upon assumed and observed distributions of the data.
A numerical approach for modeling unsaturated flow is developed for heterogeneous simulations of fractured tuff generated using a geostatistical method. Cross correlations of hydrologic properties and upscaling of moisture retention curves is discussed. The approach is demonstrated for a study of infiltration at Yucca Mountain.
The regulations that currently govern repositories for spent fuel and high-level waste require demonstrations that are sometimes described as impossible to make. To make them will require an understanding of the current and the future phenomena at repository sites; it will also require credible estimates of the probabilities that the phenomena will occur in the distant future. Experts in many fields{emdash}earth sciences, statistics, numerical modeling, and the law{emdash}have questioned whether any amount of data collection can allow modelers to meet these requirements with enough confidence to satisfy the regulators. In recent years some performance assessments have begun to shed light on this question because they use results of actual site investigations. Although these studies do not settle the question definitively, a review of a recent total-system assessment suggests that compliance may be possible to demonstrate. The review also suggests, however, that the demonstration can be only at the ``reasonable`` levels of assurance mentioned, but not defined, in the regulations.
Previous laboratory investigations of tuff have shown that porosity has a dominant, general effect on mechanical properties. As a result, it is very important for the interpretation of mechanical property data that porosity is measured on each sample tested. Porosity alone, however, does not address all of the issues important to mechanical behavior. Variability in size and distribution of pore space produces significantly different mechanical properties. A nondestructive technique for characterizing the internal structure of the sample prior to testing is being developed and the results are being analyzed. The information obtained from this technique can help in both qualitative and quantitative interpretation of test results.
In situ thermomechanical experiments are planned as part of the Yucca Mountain Site Characterization Project that require instruments to measure stress and displacement at temperatures that exceed the typical specifications of existing geotechnical instruments. A high degree of instrument reliability will also be required to satisfy the objectives of the experiments, therefore a study was undertaken to identify areas where improvement in instrument performance was required. A preliminary list of instruments required for the experiments was developed, based on existing test planning and analysis. Projected temperature requirements were compared to specifications of existing instruments to identify instrumentation development needs. Different instrument technologies, not currently employed in geotechnical instrumentation, were reviewed to identify potential improvements of existing designs for the high temperature environment. Technologies with strong potentials to improve instrument performance with relatively high reliability include graphite fiber composite materials, fiber optics, and video imagery.
As a follow-on to Sandia`s 1991 preliminary total-system performance assessment of the Yucca Mountain site, this paper presents results of some sensitivity analyses that were done using results from the 1991 study. Two conceptual models of unsaturated-zone flow and transport at Yucca Mountain were included in the study, including both aqueous and gaseous releases. The sensitivities are quite different for the two models. For the composite-porosity model, the results are most sensitive to groundwater percolation flux, gaseous transport time, container lifetime, and fuel-matrix-alteration rate. For the weeps model, the results are most sensitive to parameters used to characterize fracture flow (fracture aperture and fracture connectivity) and infiltration (percolation flux and weep-episode factor).
The event-tree method of scenario construction has been chosen for the Yucca Mountain performance assessment. Its applicability and suitability to the problem are discussed and compared with those of the Nuclear Regulatory Commission (NRC) method. The event-tree method is appropriate for an incompletely characterized site, where there must be an evolving understanding, over time, of the processes at work, for a site that may require analysis of details in specific context, and when the scenario functions to guide site characterization. Anticipating the eventual requirement for using the NRC method, we show that the event-tree method can be translated to the NRC format after final scenario screening.
Chemical vapor deposition (CVD) is a widely used method for depositing thin films of a variety of materials. Applications of CVD range from the fabrication of microelectronic devices to the deposition of protective coatings. New CVD processes are increasingly complex, with stringent requirements that make it more difficult to commercialize them in a timely fashion. However, a clear understanding of the fundamental science underlying a CVD process, as expressed through computer models, can substantially shorten the time required for reactor and process development. Research scientists at Sandia use a wide range of experimental and theoretical techniques for investigating the science of CVD. Experimental tools include optical probes for gas-phase and surface processes, a range of surface analytic techniques, molecular beam methods for gas/surface kinetics, flow visualization techniques and state-of-the-art crystal growth reactors. The theoretical strategy uses a structured approach to describe the coupled gas-phase and gas-surface chemistry, fluid dynamics, heat and mass transfer of a CVD process. The software used to describe chemical reaction mechanisms is easily adapted to codes that model a variety of reactor geometries. Carefully chosen experiments provide critical information on the chemical species, gas temperatures and flows that are necessary for model development and validation. This brochure provides basic information on Sandia`s capabilities in the physical and chemical sciences of CVD and related materials processing technologies. It contains a brief description of the major scientific and technical capabilities of the CVD staff and facilities, and a brief discussion of the approach that the staff uses to advance the scientific understanding of CVD processes.
This paper presents a brief summary of condition monitoring results from an NRC-sponsored test program on aging, condition monitoring, and accident testing of Class 1E cables. In addition, since the program has been completed and the final reports have been published, this paper presents a list of references, along with abstracts for each reference. This list can serve as a guide for finding references to any desired information on the test program in varying levels of detail. The major conclusions of the test program with regard to condition monitoring were as follows: (a) of the parameters tested, elongation at break had the best correlation with aging for the most cable types; (b) hardness and indenter modulus (performed using the cable indenter developed under Electric Power Research Institute (EPRI) sponsorship) measurements both increased with aging for some of the materials, especially the jacket materials, and the modulus measurements were significantly more sensitive to aging than the hardness measurements; (c) where indenter modulus was sensitive to aging, it was most sensitive in the later stages of aging, after the elongation had reached nearly 0%; (d) density generally increased with aging for most materials, but some changes were inconsistent; and (e) with only a few exceptions, tensile strength and a number of different electrical measurements did not correlate well with aging.
A fundamental concern in the design of the potential repository at Yucca Mountain. Nevada is the response of the host rock to the emplacement of heat-generating waste. The thermal perturbation of the rock mass has implications regarding the structural, hydrologic. and geochemical performance of the potential repository. The phenomenological coupling of many of these performance aspects makes repository thermal modeling a difficult task. For many of the more complex, coupled models, it is often necessary to reduce the geometry of the potential repository to a smeared heat-source approximation. Such simplifications have impacts on induced thermal profiles that in turn may influence other predicted responses through one- or two-way thermal couplings. The effect of waste employment layout on host-rock thermal was chosen as the primary emphasis of this study. Using a consistent set of modeling and input assumptions, far-field thermal response predictions made for discrete-source as well as plate source approximations of the repository geometry. Input values used in the simulations are consistent with a design-basis a real power density (APD) of 80 kW/acre as would be achieved assuming a 2010 emplacement start date, a levelized receipt schedule, and a limitation on available area as published in previous design studies. It was found that edge effects resulting from general repository layout have a significant influence on the shapes and extents of isothermal profiles, and should be accounted for in far-field modeling efforts.
Calculations of residual stresses in braze joints are required to validate designs for a variety of metal/ceramic joining applications. In particular, finite element analysis (FEA) codes have the capability of incorporating either elastic-plastic or minimum creep rate constitutive models for the braze material. This paper presents both elevated temperature mechanical properties correlations for the eutectic Ag-Cu alloy, along with FEA results which use this data in calculating residual stresses in a generic metal/ceramic ``shear'' type braze joint. Three constitutive relations have been developed for eutectic Ag-Cu alloy: (i) an elastic/plastic correlation incorporating temperature-dependent yield stress and work hardening data, (ii) a high temperature minimum creep rate correlation with a temperature-dependent stress exponent and (iii) a minimum creep rate correlation using the Garofalo hyperbolic sine (sinh) equation. FEA calculations are presented for a eutectic Ag-Cu braze joint between metallized alumina ceramic and either Fe-29Ni-17Co or Fe-27Ni-25Co alloys using the three different constitutive relations for the brazement. The two creep correlations, since they are time-dependent, permit a study of the effect of various cooldown cycles on the maximum residual stress in the alumina ceramic. For the cooldown profiles studied in this paper, lower residual stresses are predicted in the ceramic-relative to the elastic-plastic model - when either of the two creep models are used as the constitutive law for the eutectic Ag-Cu braze joint. A second important result is that the simulations which incorporate the Fe-29-Ni-17Co alloy show higher peak stresses than the Fe-27Ni-25Co alloy at 420°C, along with much lower peak stresses compared to Fe-27Ni-25Co alloy at room temperature. The reason for this somewhat surprising behavior can be understood in terms of the coefficient of thermal expansion for the two Fe-Ni-Co alloys.
A description of ion-irradiation-induced reduction in the photoluminescence (PL) signal from porous silicon is given and a simple model which is consistent with a nanocrystalline Si structure is presented. Ion irradiation with 250 keV Ne is used to controllably reduce the integrated PL signal by 20% after a fluence of 4*1012 Ne cm-2 and completely eliminate the PL signal after a fluence of 4*1013 Ne cm-2. The use of vacuum and air annealing to recover ion-induced damage is also described, but the high temperatures for annealing cause elimination of the PL signal.
Proceedings, Annual Technical Meeting - Institute of Environmental Sciences
Benham, R.A.; Duggins, B.D.
Pyro shock loads are generated in many missile or rocket systems when stages are separated or shrouds are removed. These shocks are localized, of short rise time (10's of ns) and of very high stress level. This paper will document some anomalous behavior that occurs when pyro shock accelerometers (Endevco 7270A) are exposed to levels of high frequency shock that is higher than the manufacturer's recommended limits. Such shocks occur in many pyro shock events. Standard, accepted recording techniques can produce totally erroneous data with no obvious indicator that the data is in error. Wide band data recording, along with Fourier Analysis of the data, and dynamic analysis, made by the gage manufacturer of the transducer, allow recognition of some of the non-standard response modes excited but no method of quantifying the corrupted data has been developed. Wide band recording, which will preserve the data in the gage resonance range and above, are required to insure understanding of these pyro shock events.
We have measured the efficiency (tracks per incident neutron) of pure CR-39 for detecting DD and DT neutrons. Neutrons having average energies of 2.9 MeV (DD) and 14.8 MeV (DT) were produced by a 200-keV electrostatic accelerator and the neutron yields were measured using the associated particle counting technique. All CR-39 samples irradiated by DD or DT neutrons were etched for 2 h in a 70°, 6.25-N- NaOH bath. For bare CR-39, the efficiencies for detecting 2.9- and 14.8-MeV neutrons were found to be (1.3±0.4)×10 -4 and (5.0±1.8)×10-5, respectively. We also investigated using CR-39 and polyimide as proton radiators. For detecting 2.9-MeV neutrons, the radiators had no significant effect on efficiency; but for detecting 14.8-MeV neutrons the polyimide radiator increased the efficiency to (7.8±2.8)×10-5.
Progress in Z-pinch experiments at Sandia's Saturn facility have underscored a need for an absolute yield measurement for DD fusion neutrons. The technique chosen for making this absolute yield measurement was neutron activation of indium metal samples. To calibrate the technique, a 175-keV deuteron beam was allowed to impinge on a 3.0-μm-thick erbium deuteride target, producing neutrons through the 2H(d,n)3He fusion reaction. The neutron flux produced at 0° and incident on nominal 5-g indium samples was determined by the associated particle method. This method employed protons measured from the 2H(d,p)3H reaction to infer the neutron flux produced. After neutron irradiation, the activity of the indium samples was measured with a Ge gamma-ray detector. The total activity of the metastable state 115mIn (336.23 keV) was measured, compared with the total incident flux, and a calibration factor (indium counts/neutron/gram of indium) determined. For completeness, a calibration factor for DT neutrons from the 3H(d,n)4He fusion reaction was also obtained through the measured activity of the metastable state 114mIn(190.29 keV). The experiment and the measured calibration factors for both reactions are described in the paper.
The CR-39/range-filter technique measures ion energy by determining the maximum filter thickness which ions can penetrate. CR-39 located behind the filter records the ions. This method is used to measure peak voltage in pulsed power accelerators. We investigated range and straggling effects in this diagnostic by exposing it to 8- and 15-MeV protons for both Al and Ta filters. The range agreed with published values to better than ±6%. The range straggling decreased for higher incident ion energy and lower atomic number, as expected, although there were differences up to a factor of 1.7 between the experimental values and predictions. The dependence of the track diameter distribution on ion energy enabled us to establish a signature which is characteristic of ions which penetrate a filter, via straggling. These results can be used to evaluate the errors present when this diagnostic is used to measure accelerator voltage.
In recent proton beam experiments on PBFA-II, foam-filled gold targets and gas-filled spherical exploding pushers were shot as physics targets. Surrounding these targets were gold foils used to characterize the beam. The target fabrication and characterization are presented in this paper.
Because a direct measurement of the voltage (V) in pulsed power bremsstrahlung sources can be difficult, the energy spectrum of x rays emitted is sometimes used to infer V. Both the voltage and current in such sources vary with time. Moreover, for modern x-ray simulators with multiple cathodes, multiple voltages may exist simultaneously. We demonstrate here how such sources lead to systematic errors in several types of simple-to-field x-ray voltage measurements, especially those with broad spectral response functions, when calibrated against constant-potential bremsstrahlung spectra.
We have built a five-channel, x-ray detector array based on diamond photoconducting detectors (PCDs). The diamond elements have dimensions of 3 mm × 1 mm × 1 mm (or 0.5 mm). We use diamond PCDs for their stability, flat spectral response, and low leakage currents. The good time response of diamond PCDs is due to the 100-ps electron/hole recombination time. Filters were designed to give information in the 1-10-keV spectral region. Calibration of the diamond PCDs showed sensitivities between 4 and 7 × 10-4 A/W for a bias of 100 V. We shall present data from z-pinch experiments on Saturn.
Numerical simulations of perforation in steel plates involve the treatment of material failure during the perforation process. One way to model physical material separation is to delete failed elements from the analysis based on an appropriate failure criterion. Different algorithms were used in different transient finite element codes to delete failed elements. This investigation compares the results of PRONTO 2D and LS-DYNA2D codes for a specific steel plate perforation problem. Influences of the deletion algorithms on material parameters are discussed.
A framework for coupled elastoplastic and damage theories is developed, following a rigorous thermodynamic procedure. This framework is sufficiently general to include anisotropic plasticity and damage formulations. Both the plastic yield and damage functions are constructed using homogeneous functions of degree one. The principle of maximum dissipation or maximum entropy production is used to derive the evolution relations together with the loading and unloading conditions. In addition, the convexity of the undamaging elastic domain is shown. For plasticity the resulting evolution of the plastic strains corresponds to an associative flow. This general framework is shown to be sufficiently general to describe several popular theories for both plasticity and damage. Limitations of some existing damage theories are discussed.
Continuum damage theories describe the progressive reduction in stiffness and strength of brittle materials resulting from the initiation and growth of microcracks and microvoids. When brittle materials are loaded into the nonlinear regime, they often exhibit localized zones of intense deformation and the eventual formation of macrocracks. Criteria for diffuse and discontinuous bifurcations have previously been developed and used to study the initiation of necking and localization in elastic-plastic materials. In this investigation, the same bifurcation criteria are applied to continuum damage theories. Since the bifurcation criteria depend on the fourth-order tangent modulus tensor, the first step in this investigation is the derivation of the tangent modulus tensor for a general continuum damage theory. An eigenanalysis of the symmetric part of the tangent modulus tensor is then shown to fully characterize the potential diffuse and discontinuous bifurcations associated with a given continuum damage theory.
As part of the NRC-sponsored program to study the implications of Generic Issue 57, Effects of Fire Protection System Actuation on Safety-Related Equipment,'' a subtask was performed to evaluate the applicability of formal decision analysis methods to generic issues cost/benefit-type decisions and to apply these methods to the GI-57 results. In this report, the numerical results obtained from the analysis of three plants (two PWRs and one BWR) as developed in the technical resolution program for GI-57 were studied. For each plant, these results included a calculation of the person-REM averted due to various accident scenarios and various proposed modifications to mitigate the accident scenarios identified. These results were recomputed to break out the benefit in terms of contributions due to random event scenarios, fire event scenarios, and seismic event scenarios. Furthermore, the benefits associated with risk (in terms of person-REM) averted from earthquakes at three different seismic ground motion levels were separately considered. Given this data, formal decision methodologies involving decision trees, value functions, and utility functions were applied to this basic data. It is shown that the formal decision methodology can be applied at several different levels. Examples are given in which the decision between several retrofits is changed from that resulting from a simple cost/benefit-ratio criterion by virtue of the decision-makinger's expressed (and assumed) preferences.
Leonard, J.A.; Floyd, H.L.; Parrott, L.; Goetsch, B.; Doran, L.
This issue describes several innovative technologies in modern manufacturing. Methods in which the HIRCIS sensor may cut costs in precision machining are described. Computer models and experimental methods aid in the chemical vapor deposition of high-temperature coatings. Shared computer networks provide communication for interactive collaboration. Sol-gel processing of tailored thin films furnish low cost, high quality glass coatings at room temperature. Integrated circuit characterization tools and expertise are available to improve quality and reliability in the microelectronic industry.
This paper describes preliminary experiments to investigate electron-beam radiolysis of model compounds appropriate for crude oil spills on water or soil. Since no previous work in this area is known to exist, the rate of destruction of such concentrated organic materials in aqueous media is not known. The experiments conducted here were designed to provide preliminary estimates of the destruction rate and the estimated costs. Samples of model compounds were irradiated to dose levels up to 700 Mrad (H{sub 2}0) and the change in chemical composition was determined by mass spectrometry/gas chromatography and Fourier transform infrared spectroscopy. It was found that a dose of 700 Mrads reduced the liquid volume of the model compound by 60% and that the major effect of irradiation was the formation of long chain alkanes and dimethyl and ethyl benzenes. Under certain conditions a solid polymer was found to form. When alcohol was present in the model compound, additional products included small quantities of ethane diodic acid, butanol, butanediol, and various other alcohols. Further research is recommended to obtain a better analysis of the products, better values for the destruction rates, and better understanding of dose rate effects.
For nearly 10 years, the Gould Electronics, Incorporated manufacturing plant in Chandler, Arizona, has been a model of how medium-temperature solar thermal energy systems can produce economical industrial process heat (IPH). In 1982, a solar IPH system was designed and built on the site by Solar Kinetics, Inc. The system has remained in operation and continues to provide economical process heat for Gould`s copper foil manufacturing operation. System performance and availability has fluctuated over the years, reaching a low point in early 1990 when the system was nearly inoperative because of equipment reliability problems. Gould teamed with engineers from Sandia National Laboratories` (Sandia) Solar Thermal Design Assistance Center to develop a plan to solve the technical problems and refurbish the field. The IPH system is currently operating at over 90-percent equipment availability, returning to Gould a net energy cost savings on the order of $7,500 per month. This paper presents the history and operation of the system from the perspective of the end user and describes the phased upgrade program undertaken with Sandia to refurbish the system.
The Jet Propulsion Laboratory is developing a large space-truss to support a micro-precision interferometer. A finite element model will be used to design and place passive and active elements in the truss to suppress vibration. To improve the model`s predictive capability, it is desirable to identify uncertain structural parameters in the model by utilizing experimental modal data. Testing of both the components and the system was performed to obtain the data necessary to identify the structural parameters. Extracting a modal model, absent of bias errors, from measured data requires great care in test design and implementation. Testing procedures that are discussed include: verification of non-constraining shaker attachment, quantification of the non-linear structural response, and the design and effects of suspension systems used to simulate a free structure. In addition to these procedures, the accuracy of the measured frequency response functions are evaluated by comparing functions measured with random excitation, using various frequency resolutions, and with step sine excitation.
This publication presents information from Sandia laboratories concerning developments in the following areas: a miniaturized sensor system for the testing and analysis of hazardous wastes;a cross-well seismic receiver for petroleum deposit detection; and computer codes for designing dish-stirling sytems.
The design, calibration, and preliminary test results for an underwater shock gauge are presented. The active element is a 25-{mu}m thick polyvinylidene fluoride shock sensor providing rise times as short as 50 ns. Fast rise time is essential to accurate recording of shock pulses with durations of only a few microseconds. The piezoelectric polymer provides a self-generating pressure sensor requiring neither amplification nor additional active electronic circuitry. The gauge package is designed to minimize electromagnetic interference from the high-voltage fire set used to power the exploding bridge wire pressure source. The gauge package is constructed to withstand the initial water shock as well as subsequent reactions in the water that result in strong water motion and bubble generation. Thin-film diaphragm sensors are not sturdy enough to withstand this environment. Initial tests show that the gauge responds in 200 ns in water and that low-frequency response is sufficient to allow recording for at least 40 {mu}s after the initial shock arrival.
Performance and functionality increases in network environments have in the need for readily accessible mass storage. UNIX{reg_sign}-based networks and mass storage systems are providing the required connectivity and interoperability, however, how UNIX-based mass storage systems are being used is not well documented. This paper describes a study of the usage of the UNIX-based Network Storage Service at Sandia National Laboratories.
A discrete element computer program, DMC (Distinct-Motion Code), has been used for several years to simulate blasting-induced rock motion. Recent enhancements of DMC`s capabilities have included addition of an algorithm that couples together rock motion and gas flow. This allows the user to specify a particular explosive which also specifies equation-of-state and other parameters necessary to model explosive gas flow from the blastwell. Rock loading by the flowing gas is calculated automatically. The mechanism for calculating the rock loading is the subject of this paper. The rock motion effects the gas flow calculation by changing the porosity. DMC is currently being used on a SLTN SPARCstation 2 computer workstation.
Solder wettability of Class II environmentally exposed Cu substrates coated with an organic solderability preservative (OSP) is being investigated. The OSP coatings slightly retarded the wetting behavior of 60Sn-40Pb solder during baseline testing of unaged coupons. A nominal increase in wetting angle, or decrease in wettability, was observed on the inhibited surfaces, particularly when less active fluxes were used. Small increases in the wetting time and decreases in the wetting rate were also measured. Simulated accelerated aging tests are underway to determine the effects of aging in a typical indoor industrial environment on the solder wettability of OSP coated Cu.
Sandia operated by AT&T for the US Department of Energy. Sandia has a billion dollar annual budget and over 8,000 employees. Sandia`s main sites are in Albuquerque, New Mexico; Livermore, California; and Tonopah, Nevada. Sandia has a broad base of engineering and scientific skills that supports the whole product cycle from advanced R&D through manufacturing and end-user support. Sandia`s original mission was to develop the non-nuclear portion of nuclear weapons. In the 1970s, the mission was expanded to include technical work on conventional and alternative energy sources. Recently, the mission was further expanded to include technology transfer and US competitiveness. This report describes the activities in the Component Development and Engineering Support Division 2000 (indicated by the bold lines on the organization chart). Division 2000 develops electrical, electronic, optical, explosive, mechanical, and other components that are the core products of Sandia systems. The Division also develops advanced capabilities in CAD/CAE, test, nondestructive test, programming, reliability, failure analysis, and simulation that are part of the core services required by Sandia systems. For each of the core products and services described in this brochure, there is a corresponding set of science and engineering capabilities that are Sandia`s core competencies. Also, there are systems groups that use these core products and services to develop ultra-reliable systems for Sandia`s customers. Most of these groups have literature available describing their capabilities and expertise.
Nuclear power plants have experienced actuations of fire protection systems (FPSs) under conditions for which these systems were not intended to actuate. They have also experienced advertent actuations with the presence of a fire. These actuations have often damaged nearby plant equipment. A review of past occurrences of both types of such events on nuclear power plant safety has been performed. Thirteen different scenarios leading to actuation of fire protection systems due to a variety of causes were identified. These scenarios range from inadvertant actuation caused by human errors to hardware failures and include seismic root causes and seismic/fire interactions. A quantification of these thirteen scenarios, where applicable, was performed on a BWR4/MKI. This report estimates the contribution of FPS actuations to core damage frequency and to risk.
Data are presented from the Geomechanical Evaluation (first phase), a very large scale in situ test fielded underground at the Waste Isolation Pilot Plant (WIPP). These data include selected fielding information, test configuration, instrumentation activities, and comprehensive results from a large number of gages. Construction of the test began in December 1984 and the test has been in operation since that time; gage data in this report cover the period from December 1984 through November 1990.
Nuclear power plants have experienced actuations of fire protection systems (FPSs) under conditions for which these systems were not intended to actuate and also have experienced advertent actuations with the presence of a fire. These actuations have often damaged safety-related equipment. A review of the impact of past occurrences of both types of such events and their impact on plant safety systems, an analysis of the risk impacts of such events on nuclear power plant safety, and a cost-benefit analysis of potential corrective measures have been performed. Thirteen different scenarios leading to actuation of fire protection systems due to a variety of causes were identified. These scenarios ranged from inadvertent actuation caused by human error to hardware failure, and include seismic root causes and seismic/fire interactions. A quantification of these thirteen root causes, where applicable, was performed on generically applicable scenarios. This document, Volume 2, contains appendices A,B, and C of this report.
Nuclear power plants have experienced actuations of fire protection systems (FPSs) under conditions for which these systems were not intended to actuate and also have experienced advertent actuations with the presence of a fire. These actuations have often damaged nearby plant equipment. A review of the impact of past occurrences of both types of such events, a quantification of the risk of FPS actuation, a sensitivity study of the quantification of the risk of FPS actuation and risk calculations in terms of person-REM have been performed. Thirteen different scenarios leading to actuation of fire protection systems due to a variety of causes were identified. A quantification of these thirteen scenarios, where applicable, was performed on a 3-loop Westinghouse Pressurized water Reactor (PWR). These scenarios ranged from inadvertent actuation caused by human error to hardware failures, and include seismic root causes and seismic/fire interaction. This report estimates the contribution of FPS actuations to core damage frequency and risk.
The VICTORIA model of radionuclide behavior in the reactor coolant system (RCS) of a light water reactor during a severe accident is described. It has been developed by the USNRC to define the radionuclide phenomena and processes that must be considered in systems-level models used for integrated analyses of severe accident source terms. The VICTORIA code, based upon this model, predicts fission product release from the fuel, chemical reactions involving fission products, vapor and aerosol behavior, and fission product decay heating. Also included is a detailed description of how the model is implemented in VICTORIA, the numerical algorithms used, and the correlations and thermochemical data necessary for determining a solution. A description of the code structure, input and output, and a sample problem are provided.
Brine inflow to the Waste Isolation Pilot Plant is important in assessing the performance of the repository, and a mechanistic model is needed for performance calculations. Brine inflow experiments are being conducted, and formation parameters such as the permeability and diffusivity are inferred from these data using a simplified one-dimensional radial, uniform property, single-phase Darcy flow model. This model has met with limited success in interpreting some of the recent data. Much of the data could not be satisfactorily fit with the above model because the brine inflow rate increases with time, so a more mechanistic model is being developed based on the TOUGH and TOUGH2 computer codes. These codes are much more complex than the simplified model and include a number of parameters that have not been measured. Therefore, a one-dimensional brine inflow sensitivity study has been undertaken to evaluate the importance of a number of these parameters in influencing the behavior of brine inflow to open boreholes. In addition, two-phase conditions have been included in the study, and the sensitivity of gas inflow rates and the formation pressure and saturation distributions after 1 year are examined. These results should be helpful in determining what additional measurements are necessary to assist in the development of a more mechanistic brine inflow model.
The Precision Linear Shaped Charge (PLSC) design concept involves the independent fabrication and assembly of the liner (wedge of PLSC), the tamper/confinement, and explosive. The liner is the most important part of an LSC and should be fabricated by a more quality controlled, precise process than the tamper material. Also, this concept allows the liner material to be different from the tamper material. The explosive can be loaded between the liner and tamper as the last step in the assembly process rather than the first step as in conventional LSC designs. PLSC designs are shown to produce increased jet penetrations in given targets, more reproducible jet penetration, and more efficient explosive cross sections using a minimum amount of explosive. The Linear Explosive Shaped Charge Analysis (LESCA) code developed at SandiaNational Laboratories has been used to assist in the design of PLSCs. LESCA predictions for PLSC jet penetration in aluminum targets, jet tip velocities and jet-target impact angles are compared to measured data.
Results are presented of a detailed survey of the present state of scientific understanding of cloud electrification processes and lightning warning technology. A review is given of the principles of operation and demonstrated performance factors of lightning strike location technologies and associated commercial products. Emphasis is given to the local lightning warning problem, which is divided into two categories: detection and tracking of active storms that originate outside of and move into the declared safety zone, and early detection of cloud electrification that initiates within the zone. A prototype single-station warning system design is presented that is intended to accumulate data simultaneously from a complement of different types of sensors during intervals immediately preceding the onset of lightning conditions within the area of coverage. The resultant data base will be analyzed statistically to identify the most promising combinations of early warning indicators and to quantify their reliability as a function of the warning intervals they provide.
Multiple sources of variation will often affect the stability of a manufacturing process. Items from different batches may vary because of variation both within a batch and among different batches. Potential sources of variation include within run, run-to-run and week-to-week differences in a manufacturing process. If multiple sources of variation are present, traditional control chart methods may not be appropriate. In this report we develop control charts for monitoring these sources of variation as well as the process average. An example of how to use the control charts is given, using Field 89 data from functional testing of the MC3854 neutron tube.
We have determined the effects that orientation and stress have on chemically prepared Pb(Zr,Ti)0{sub 3} (PZT) film properties. Systematic modification of the underlying substrate technology has permitted us to fabricate suites of films that have various degrees of orientation at a constant stress level, and to also fabricate films that are in different states of stress, but have similar orientation. We have fabricated highly oriented films of the following compositions: PZT 60/40, PZT 40/60 and PZT 20/80. Remanent polarizations ({approx}60 {mu}C/cm{sup 2}) greater than the best bulk polycrystalline ferroelectrics were obtained for PZT 40/60 films that were under compression and highly (001) oriented. While we show that systematically varying orientation influences ferroelectric properties, film stress also has a considerable effect. Perhaps the most important concept presented in this paper is that the sign of the film stress at the Curie point controls the type of ferroelectric behavior exhibited by PZT thin films. Further, our stress measurements as a function of thermal history indicate that the coefficient of thermal expansion of the paraelectric state is critical in determining the type of film ferroelectric behavior.
GROPE is a program that examines the input to a finite element analysis (which is in the GENESIS database format) or the output from an analysis (in the EXODUS database format). GROPE allows the user to examine any value in the database. The display can be directed to the user`s terminal or to a print file.
A Quality Management System was defined by Sub-Process teams within Data Analysis Department 2722. Each of the processes is concerned with a different phase of work for intemal customers (members of the Department) and for external customers (Sandians external to the Department, or agencies outside of Sandia). This report identifies and defines the crucial Work Processes of the Department, where each Process is documented in a separate ``Chapter.`` This report documents the effort of the Data Analysis Department to effectively provide services to its customers and to assess/improve these services. Thus this report is intended to be a ``living document`` for the Department and each member of the Department is expected to follow its guidelines.
Solar heat gain inside a radiation-shielded forklift operator compartment can be a significant problem due to the ``greenhouse effect``. Battery power prohibits the use of a refrigerant type of air-conditioning system, which limits the interior temperature to be approximately equal to the outside ambient temperature through alternative cooling methods. A heat transfer analysis is performed to determine the amount of solar heat gain in this type of mobile vehicle shelter. Various results are presented that depend on exterior surface finish and temperature difference between inside and outside ambient. An amount of forced air flow along with several design recommendations are then specified to rid the compartment of this excess heat.
Sandia National Laboratories operates the Primary Standards Laboratory for the Department of Energy, Albuquerque Operations Office (DOE/AL). This report summarizes metrology activities that received emphasis in the first half of 1992 and provides information pertinent to the operation of the DOE/AL system wide Standards and Calibration Program.
Aprepro is an algebraic preprocessor that reads a file containing both general text and algebraic, string, or conditional expressions. It interprets the expressions and outputs them to the output file along with the general text. The syntax used in Aprepro is such that all expressions between the delimiters and are evaluated and all other text is simply echoed to the output file. Aprepro contains several mathematical functions, string functions, and flow control constructs. In addition, functions are included that, with some additional files, implement a units conversion system and a material database lookup system. Aprepro was written primarily to simplify the preparation of parameterized input files for finite element analyses at Sandia National Laboratories; however, it can process any text file that does not use the characters.
GJOIN is a two- or three-dimensional mesh combination program. GJOIN combines two or more meshes written in the GENESIS mesh database format into a single GENESIS mesh. Selected nodes in the two meshes that are closer than a specified distance can be combined The geometry of the mesh databases can be modified by scaling, offsetting, revolving, and mirroring. The combined meshes can be further modified by deleting, renaming, or combining material blocks, sideset identifications, or nodeset identifications. GJOIN is one of the mesh generation tools in the Sandia National Laboratories Engineering Analysis Code Access System (SEACAS). GJOIN is typically used with the other SEACAS mesh generation codes GEN3D, GENSHELL, GREPOS, and Aprepro.
This report describes preliminary probabilistic sensitivity analyses of long term gas and brine migration at the Waste Isolation Pilot Plant (WIPP). Because gas and brine are potential transport media for organic compounds and heavy metals, understanding two-phase flow in the repository and the surrounding Salado Formation is essential to evaluating long-term compliance with 40 CFR 268.6, which is the portion of the Land Disposal Restrictions of the Hazardous and Solid Waste Amendments to the Resource Conservation and Recovery Act that states the conditions for disposal of specified hazardous wastes. Calculations described here are designed to provide guidance to the WIPP Project by identifying important parameters and helping to recognize processes not yet modeled that may affect compliance. Based on these analyses, performance is sensitive to shaft-seal permeabilities, parameters affecting gas generation, and the conceptual model used for the disturbed rock zone surrounding the excavation. Brine migration is less likely to affect compliance with 40 CFR 268.6 than gas migration. However, results are preliminary, and additional iterations of uncertainty and sensitivity analyses will be required to provide the confidence needed for a defensible compliance evaluation. Specifically, subsequent analyses will explicitly include effects of salt creep and, when conceptual and computational models are available, pressure-dependent fracturing of anhydrite marker beds.
Iterative, annual performance-assessment calculations are being performed for the Waste Isolation Pilot Plant (WIPP), which is a planned underground repository in southeastern New Mexico for the disposal of transuranic radioactive waste. The performance-assessment calculations estimate long-term (10,000-year) radionuclide releases from the disposal system to the accessible environment. The estimation of the releases is probabilistic in nature, requiring system parameters to be described with probability distributions. Because direct experimental data in some areas are presently insufficient or unavailable to form the required distributions, researchers at Sandia National Laboratories have used a formalized expert-judgment elicitation procedure to determine the state of knowledge in these areas. Expert judgment was used to estimate the concentrations of specific radionuclides in a repository brine that might be forced up an intruding borehole, and also to estimate the distribution coefficients to determine the retardation of radionuclides in the overlying Culebra Dolomite. The variables representing these concentrations and coefficients have been shown by 1990 sensitivity analyses to be among the set of parameters making the greatest contribution to the uncertainty in WIPP performance assessment predictions. Using available information, the experts (one expert panel addressed concentrations and a second panel addressed retardation) were briefed on the problem of insufficient experimental data and were formally elicited to obtain probability distributions that characterize the uncertainty in fixed, but unknown, quantities. The probability distributions developed by the experts were incorporated into the 1991 and 1992 performance-assessment calculations.
Using concepts of decision analysis, this paper examines how government policy makers might consider and evaluate the contribution of additional inspection, openness, and confidence-building measures to diplomatic questions involving compliance with arms control agreements. During the current debate among parties to the Biological Weapons Convention as to what constitutes effective verification of compliance with that Convention, these analytical concepts were employed to evaluate some proposed inspection or confidence-building measures. Some of the salient points not bound up in the confidentiality of on-going negotiations will be summarized here.
This paper describes a current research program at Sandia National Laboratories whereby magnetic stripes are produced through the use of a new particle rotation technology. This new process allows the stripes to be produced in bulk and then held in a latent state so that they may be encoded at a later date. Since particle rotation is less dependent on the type of magnetic particle used, very high coercivity particles could provide a way to increase both magnetic tamper-resistance and accidental erasure protection. This research was initially funded by the Department of Energy, Office of Safeguard and Security as a portion of their Science and Technology Base Development, Advanced Security Concepts program. Current program funding is being provided by Sandia National Laboratories as part of their Laboratory Directed Research and Development program.
The remand of the US Environmental Protection Agency`s long-term performance standards for radioactive-waste disposal provides an opportunity to suggest modifications that would make the regulation more defensible and remove inconsistencies yet retain the basic structure of the original rule. Proposed modifications are in three specific areas: release and dose limits, probabilistic containment requirements, and transuranic-waste disposal criteria. Examination of the modifications includes discussion of the alternatives, demonstration of methods of development and implementation, comparison of the characteristics, attributes, and deficiencies of possible options within each area, and analysis of the implications for performance assessments. An additional consideration is the impact on the entire regulation when developing or modifying the individual components of the radiological standards.
Given a graph G = (V, E) where each vertex v {element_of} V is assigned a weight w(v) and each edge e {element_of} E is assigned a cost c(e), the quotient of a cut partitioning the vertices of V into sets S and {bar S} is c(S, {bar S})/min{l_brace}w(S), w(S){r_brace}, where c(S, {bar S}) is the sum of the costs of the edges crossing the cut and w(S) and w({bar S}) are the sum of the weights of the vertices in S and {bar S}, respectively. The problem of finding a cut whose quotient is minimum for a graph has in recent years attracted considerable attention, due in large part to the work of Rao and Leighton and Rao. They have shown that an algorithm (exact or approximation) for the minimum-quotient-cut problem can be used to obtain an approximation algorithm for the more famous minimumb-balanced-cut problem, which requires finding a cut (S,{bar S}) minimizing c(S,{bar S}) subject to the constraint bW {le} w(S) {le} (1 {minus} b)W, where W is the total vertex weight and b is some fixed balance in the range 0 < b {le} {1/2}. Unfortunately, the minimum-quotient-cut problem is strongly NP-hard for general graphs, and the best polynomial-time approximation algorithm known for the general problem guarantees only a cut whose quotient is at mostO(lg n) times optimal, where n is the size of the graph. However, for planar graphs, the minimum-quotient-cut problem appears more tractable, as Rao has developed several efficient approximation algorithms for the planar version of the problem capable of finding a cut whose quotient is at most some constant times optimal. In this paper, we improve Rao`s algorithms, both in terms of accuracy and speed. As our first result, we present two pseudopolynomial-time exact algorithms for the planar minimum-quotient-cut problem. As Rao`s most accurate approximation algorithm for the problem -- also a pseudopolynomial-time algorithm -- guarantees only a 1.5-times-optimal cut, our algorithms represent a significant advance.
The ability to design gating systems that reliably feed and support investment castings is often the result of ``cut-and-try`` methodology. Factors such as hot tearing, porosity, cold shuts, misruns, and shrink are defects often corrected by several empirical gating design iterations. Sandia National Laboratories is developing rules that aid in removing the uncertainty involved in the design of gating systems for investment castings. In this work, gating geometries used for filling of thin walled investment cast 17-4PH stainless steel flat plates were investigated. A full factorial experiment evaluating the influence of metal pour temperature, mold preheat temperature, and mold channel thickness were conducted for orientations that filled a horizontal flat plate from the edge. A single wedge gate geometry was used for the edge-gated configuration. Thermocouples placed along the top of the mold recorded metal front temperatures, and a real-time x-ray imaging system tracked the fluid flow behavior during filling of the casting. Data from these experiments were used to determine the terminal fill volumes and terminal fill times for each gate design.
This paper studied the behavior of retained system poles and transmission zeros in a control design model when the model is truncated. The sensitivity of the transmission zeros due to the tuncation of system dynamics was analytically obtained. The sensitivity of system poles to the truncation of system dynamics was shown to be zero as expected. The effects of actuator-sensor type and location was also studied. The results were illustrated with two example problems. The effect of transmission zero shifts in control design models and the controllers designed from them was illustrated with an example.
A telerobotic system demonstration was developed for the Department of Energy`s Accident Response group to highlight the applications of telerobotic vehicles to accident site inspection. The proof-of- principle system employs two mobile robots, Dixie and RAYBOT, to inspect a simulated accident site. Both robots are controlled serially from a single driving station, allowing an operator to take advantage of having multiple robots at the scene. The telerobotic system is described and some of the advantages of having more than one robot present are discussed. Future plans for the system are also presented.
This report will present a brief overview of the transient dynamics capabilities at Sandia National Laboratories, with an emphasis on recent new developments and current research. In addition, the Sandia National Laboratories (SNL) Engineering Analysis Code Access System (SEACAS), which is a collection of structural and thermal codes and utilities used by analysts at SNL, will be described. The SEACAS system includes pre- and post-processing codes, analysis codes, database translation codes, support libraries, Unix shell scripts for execution, and an installation system. SEACAS is used at SNL on a daily basis as a production, research, and development system for the engineering analysts and code developers. Over the past year, approximately 190 days of CPU time have been used by SEACAS codes on jobs running from a few seconds up to two and one-half days of CPU time. SEACAS is running on several different systems at SNL including Cray Unicos, Hewlett Packard HP-UX, Digital Equipment Ultrix, and Sun SunOS. An overview of SEACAS, including a short description of the codes in the system, will be presented. Abstracts and references for the codes are listed at the end of the report.
A simple, approximate model of parachute inflation is described. The model is based on the traditional, practical treatment of the fluid resistance of rigid bodies in nonsteady flow, with appropriate extensions to accommodate the change in canopy inflated shape. Correlations for the steady drag and steady radial force as functions of the inflated radius are required as input to the dynamic model. In a novel approach, the radial force is expressed in terms of easily obtainable drag and reefing fine tension measurements. A series of wind tunnel experiments provides the needed correlations. Coefficients associated with the added mass of fluid are evaluated by calibrating the model against an extensive and reliable set of flight data. A parameter is introduced which appears to universally govern the strong dependence of the axial added mass coefficient on motion history. Through comparisons with flight data, the model is shown to realistically predict inflation forces for ribbon and ringslot canopies over a wide range of sizes and deployment conditions.
This document presents the quality assurance (QA) procedures for Parameter Selection and Expert Judgment Panels used by the performance Assessment Department of Sandia National Laboratories, which directly supports the Waste Isolation Pilot Plant (WIPP). Parameter Selection QA procedures described herein will be incorporated into the general Performance Assessment Quality Assurance Procedures, QAP 2-3; the Expert Judgment Panel procedures will be incorporated into QAP 2-6. Both sets of procedures will apply to all Sandia and Sandia contractor activities related to performance assessment (except where the contractor has its own approved QA procedures). This report presents the philosophy behind the QA procedures, provides the standards adopted for performance assessment Parameter Selection and Expert Judgment Panels, and discusses the implementation of these standards.
This 1991 report contains monitoring data from routine radiological and nonradiological environmental surveillance activities. Summaries of significant environmental compliance programs in progress such as National Environmental Policy Act (NEPA) documentation, environmental permits, environmental restoration (ER), and various waste management programs for Sandia National Laboratories in Albuquerque (SNL, Albuquerque) are included. The maximum offsite dose impact was calculated to be 1.3 {times} 10{sup {minus}3} mrem. The total population within a 50-mile radius of SNL, Albuquerque, received a collective dose of 0.53 person-rem during 1991 from SNL, Albuquerque, operations. As in the previous year, the 1991 operations at SNL, Albuquerque, had no discernible impact on the general public or on the environment.
This preliminary study analyzes the atmospheric entry of a solid core nuclear thermal rocket (NTR) engine under three accidental entry scenarios. Depending on the scenario, results of the analysis showed that, without external thermal protection, an aluminum pressure vessel will fail at altitudes ranging 25 to 73 km. subsequent release the core materials occurs. The graphitic based core materials will undergo partial ablation, with the percent mass loss depending on the geometry of the fuel elements. A carbon-phenolic thermal protection system was sized to prevent pressure vessel aerothermal failure. It was found to increase the mass of the NTR by approximately 15 percent.
This report examines containment requirements for spent-fuel transport containers that are transported under normal and hypothetical accident conditions. A methodology is described that estimates the probability of rod failure and the quantity of radioactive material released from breached rods. This methodology characterizes the dynamic environment of the cask and its contents and deterministically models the peak stresses that are induced in spent-fuel cladding by the mechanical and thermal dynamic environments. The peak stresses are evaluated in relation to probabilistic failure criteria for generated or preexisting ductile tearing and material fractures at cracks partially through the wall in fuel rods. Activity concentrations in the cask cavity are predicted from estimates of the fraction of gases, volatiles, and fuel fines that are released when the rod cladding is breached. Containment requirements based on the source term are calculated in terms of maximum permissible volumetric leak rates from the cask. Calculations are included for representative cask designs.
This report describes a mechanism for compiling the functional language SISAL for Sandia`s Epsilon-2 hybrid dataflow machine. The strategy couples the front-end of the standard SISAL compiler (which generates a data dependence graph intermediate form called IF1) with an optimizing code-generator for Epsilon-2. The Epsilon-2 code-generator is the back-end of a compiler for the functional language Id. It translates a data dependence graph intermediate form called Program Graphs into Epsilon-2 machine code. This report describes a translation path from IF1 graphs to Program Graphs. This report also comments on the relative merits of the IF1 and Program Graph representations.
This memorandum is a synopsis of the description and operation of the equipment used and the events accuring during the calibration of gauges on the vacuum station over the range of 0.0001 to 650 torr.
This report summarizes the environmental surveillance activities conducted by the US Environmental Protection Agency (EPA) and Reynolds Electrical and Engineering Company (REECO) for the Tonopah Test Range (TTR) operated by Sandia National Laboratories (SNL). Other environmental compliance programs such as the National Environmental Policy Act of 1969 (NEPA), environmental permits, environmental restoration, and waste management programs are also included. The 1991 SNL, TTR, operations had no discernible impact on the general public or the environment. This report 3-s prepared for the US Department of Energy (DOE) in compliance with DOE Order 5400.1.
Through a program sponsored by the US Department of Energy (DOE), Cummins Power Generation, Inc. (CPG) and Sandia National Laboratories (SNL) have entered into a joint venture to develop and commercialize economically competitive dish-Stirling systems for remote power applications. Sixteen systems, representing three generations of technology, will be developed, fielded, and tested in the Dish-Stirling Joint Venture Program (JVP). The JVP is funded equally by a consortium led by CPG and by the DOE. After completion of the program, CPG`s commercialization effort will continue with limited production expected to start in 1996. In this paper, the program plan and the technology used in the JVP are outlined. ne current status of the key system components, and the initial results of a system optimization study including current cost and performance estimates, are also provided.
Research in recent years has demonstrated the efficient use of solar thermal energy for driving endothermic chemical reforming reactions in which hydrocarbons are reacted to form syngas. Closed-loop reforming/methanation systems can be used for storage and transport of process heat and for short-term storage for peaking power generation. Open-loop reforming and gasification systems can be used for direct fuel production; for production of syngas feedstock for further processing to bulk ammonia, hydrogen, and liquid fuels; and for destruction of hazardous organic materials. To help identify the most promising areas for future development of this technology, we discuss in this paper the market potential of these applications.
FASTCAST is a Sandia National Laboratories program to produce investment cast prototypical hardware faster by integrating experimental and computational technologies into the casting process. FASTCAST uses the finite element method to characterize the metal flow and solidification processes to reduce uncertainty in the mold design. For the casting process to benefit from finite element analysis, analysis results must be available in a very short time frame. By focusing on the bottleneck of finite element model creation, automated mesh generation can drastically reduce the time span between geometry definition (design) and accurate analysis results. The increased availability of analysis results will diminish the need for trial and error approaches to acquiring production worthy mold and gating systems for investment casting. The CUBIT meshing tool kit is being developed to address the need for rapid mesh generation. CUBIT is being designed to effectively automate the generation of quadrilateral and hexahedral elements. It is a solid-modeler based, two- and three-dimensional preprocessor that prepares solid models for finite element analysis. CUBIT contains several meshing algorithms including two- and three-dimensional mapping, two- and three-dimensional paving (patented), and a general two and one-half dimensional sweeper based upon the plastering algorithm. This paper describes progress in the development of the CUBIT meshing toolkit.
The purpose of this NUREG is to provide technical information on the major components of entry control systems: identity verifiers, weapons detectors, explosives detectors, and special nuclear material (SNM) detectors. For each type of device, information is presented on principles of operation, hardware features, recommended installation, testing methods, and operational procedures. Applications to personnel, handcarried packages, bulk items, and vehicles are addressed.
We have investigated the chemistry of Cu(hfac){sub 2}, (hfac)Cu(VTMS), (hfac)Cu(2-butyne), and hfach on a Pt(111) surface. In contrast to what is observed on copper surfaces. Cu(hfac)2 and hfach lead to the formation of distinctly different adsorbed hfac species on Pt(111). This shows the importance of the copper atoms themselves in determining the surface chemistry of copper {beta}-diketonate CVD precursors. The hfac species on Pt(111) are considerably less stable than hfac on copper, suggesting that unimolecular decomposition may lead to impurity incorporation in the interfacial region when copper is deposited onto a more reactive substrate. In situ CVD studies with Cu(I) {beta}-diketonates show that the bimolecular disproportionation reaction leading to copper CVD is favored over unimolecular precursor decomposition at pressures above approximately 10{sup {minus}5} torr.
The fifth experiment of the Integral Effects Test (IET-5) series was conducted to investigate the effects of high pressure melt ejection on direct containment heating. Scale models of the Zion reactor pressure vessel (RPV), cavity, instrument tunnel, and subcompartment structures were constructed in the Surtsey Test Facility at Sandia National Laboratories. The RPV was modeled 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 hemispherical bottom head containing a graphite limiter plate with a 4-cm exit hole to simulate the ablated hole in the RPV bottom head that would be formed by ejection of an instrument guide tube in a severe nuclear power plant accident. The cavity contained 3.48 kg of water, and the basement floor inside the crane wall contained 71 kg of water, which corresponded to condensate levels in the Zion plant. A 43-kg initial charge of iron oxide/aluminium/chromium thermite was used to simulate corium debris on the bottom head of the RPV. Molten them-lite was ejected by 6.0 MPa of steam into the reactor cavity.
The purpose of this NUREG is to present technical information that should be useful for understanding and applying locking systems for physical protection and control. There are major sections on hardware for locks, vaults, safes, and security containers. Other topics include management of lock systems and safety considerations. this document also contains notes on standards and specifications and a glossary.
Creep tests were performed on a representative sample of rock salt from borehole Moss Bluff 2 (MB2), Moss Bluff dome near Houston, Texas. Moss Bluff 2 is located at the site of a compressed gas storage cavern of Tejas Power Corporation. Four triaxial experiments were conducted at two values of principal stress difference and two representative temperatures. The minimum observed creep rates at the end of each test varied between 5.2{times}10{sup {minus}9} 1/s and 2.14{times}10{sup {minus}8} 1/s. Comparisons of the present results with existing data for rock salt from other locations suggest that the steadystate creep characteristics of MB2 salt, depth 3349 ft (1098.8 m), are intermediate to those measured for the US Strategic Petroleum Reserve at West Hackberry and Bryan Hound, which included the most creep resistant rock salt ever tested at Sandia National Laboratories. Creep parameters are suggested for first-order sensitivity calculations.
The destruction of the Earth`s protective ozone layer is one of today`s largest environmental concerns. Solvent emissions released during the cleaning of printed wiring boards (PWBs) have been identified as a primary contributor to ozone destruction. No-clean soldering (sometimes referred to as self-cleaning) processes represent an ideal solution since they eliminate the need for cleaning after soldering. Elimination of solvent cleaning operations significantly reduces the emissions of ozone depleting chemicals (ODCs), reduces energy consumption, and reduces product costs. Several no-clean soldering processes have been developed over the past few years. The program`s purpose was to evaluate the no-clean soldering process and to determine if hardware produced by the process is acceptable for military applications. That is, determine if the no-clean process produces hardware that is as reliable as that soldered with the existing rosin-based flux solvent cleaning process.
Sandia National Laboratories performed random vibration and shock tests on a tritium hydride transport vessel that was packaged in an H1616-1 container. The objective of the tests was to determine if the hydride transport vessel remains leaktight under vibration and shock normally incident to transport, which is a requirement that the hydride transport vessel must meet to be shipped in the H1616-1. Helium leak tests before and after the vibration and shock tests showed that the hydride transport vessel remained leaktight under the specified conditions. There were no detrimental effects on the containment vessel of the H1616-1.
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.
Choosing the appropriate conceptual model of contaminant transport from a hazardous waste site to the underlying aquifer will assist in designing efficient site investigation and remediation strategies. One method of collecting data to support a conceptual model is by comparing ground water sampling results to soil gas sampling results that are collected through existing monitoring wells. This underutilized data collection technique is quick, easy, and inexpensive. Comparing the soil gas results to ground water results can assist in supporting or refuting a conceptual model selection. In addition, soil gas sampling from existing monitoring wells may provide an early warning detection technique to impending ground water contamination. This approach is being implemented at the Chemical Waste Landfill at Sandia National Laboratories in Albuquerque, New Mexico.
The Recirculating Linear Accelerator (RLA) utilizes the Ion Focused Regime (IFR) of beam transport plus a ramped bending field to guide the beam around the curved sections. Several issues of beam transport are considered. Beam transverse perturbations that could result in growth of the ion hose instability are analyzed. It is found that transverse kicks due to bending field errors, energy mismatches and fringe fields are the most important. The scaling of these perturbations with beam and channel parameters is derived. The effect of ramping of the bending field on the preformed plasma channel is then considered. For RLA experimental parameters the effect is found to be very small. For high energies however, in addition to axial heating, it is found that ramping the field causes compression of the plasma channel along the radius of curvature. This compression results in a quasi-equilibrium plasma electron temperature along the field lines which leads to collisionless transport towards the walls. The analysis of compression is done in an approximate way using a single particle picture and the channel expansion is analyzed using an envelope solution which gives a simple expression for the expansion time. This solution is then verified by Buckshot simulations. For a bending field of 2 kG ramped in 2 {mu}-secs and an argon channel (RLA parameters) we estimate that the channel radius doubling time (along field lines) is of the order of 0.5 {mu}-secs. Finally the effect of electron impact ionization due to axially heated electrons by the action of the inductive field is estimated. It is found that in Argon gas the electron avalanche time could be as low as 0.5 {mu}-sec which is smaller than the field ramp time.
Piping penetrations in nuclear power plant steel containments are surrounded by flexible metal bellows. The purpose of the bellows is to maintain the containment pressure boundary integrity while permitting relative movement between the piping and the containment wall. In a severe accident, bellows may be subjected to high temperatures, pressure, and combinations of lateral and axial deflections. Sandia National Laboratories (SNL), under sponsorship of the Nuclear Regulatory Commission (NRC), is performing a series of tests to investigate the performance of containment bellows under severe accident conditions.
Radioactive spent fuel assemblies are a source of hazardous waste that will have to be dealt with in the near future. It is anticipated that the spent fuel assemblies will be transported to disposal sites in spent fuel transportation casks. In order to design a reliable and safe transportation cask, the maximum cladding temperature of the spent fuel rod arrays must be calculated. The maximum rod temperature is a limiting factor in the amount of spent fuel that can be loaded in a transportation cask. The scope of this work is to demonstrate that reasonable and conservative spent fuel rod temperature predictions can be made using commercially available thermal analysis codes. The demonstration is accomplished by a comparison between numerical temperature predictions, with a commercially available thermal analysis code, and experimental temperature data for electrical rod heaters simulating a horizontally oriented spent fuel rod bundle.
Prior work has shown that the piezoelectric response of shock-compressed PVDF film prepared with attention to mechanical and electrical processing exhibits precise, well-defined, reproducible behavior to 10 GPa. Higher pressure response continues to pressures approaching 50 GPa, and appears to provide a basis for a very high pressure stress-rate gauge. Previous work shows that differences in response were sometimes observed. The present report describes studies in progress undertaken to increase the precision of the polarization of the PVDF and to develop optimum sensors and shock gauge package designs. Results obtained on such careful prepared PVDF shock gauges show that differences in electrical charge response less than few percent are observed between 10 and 25 GPa.
Recent progress in the design, synthesis, and activity testing of catalysts for partial oxidation of light alkanes is described. The first testing results for the designed halogenated dodeca-substituted iron-porphyrin catalysts are presented. The results validate the design goals selected and suggest improvements to the current catalyst designs.
Space Nuclear Reactor Systems, especially those used for propulsion, often have expected operation run times much shorter than those for land-based nuclear power plants. This produces substantially different radionuclide inventories to be considered in the safety analyses of space nuclear systems. This presentation describes an analysis utilizing ORIGEN2 and DKPOWER to provide comparisons among representative land-based and space systems. These comparisons enable early, conceptual considerations of safety issues and features in the preliminary design phases of operational systems, test facilities, and operations by identifying differences between the requirements for space systems and the established practice for land-based power systems. Early indications are that separation distance is much more effective as a safety measure for space nuclear systems than for power reactors because greater decay of the radionuclide activity occurs during the time to transport the inventory a given distance. In addition, the inventories of long-lived actinides are very low for space reactor systems.
A variety of approaches for handling effluent from nuclear thermal propulsion system ground tests in an environmentally acceptable manner are discussed. The functional requirements of effluent treatment are defined and concept options are presented within the framework of these requirements. System concepts differ primarily in the choice of fission-product retention and waste handling concepts. The concept options considered range from closed cycle (venting the exhaust to a closed volume or recirculating the hydrogen in a closed loop) to open cycle (real time processing and venting of the effluent). This paper reviews the strengths and weaknesses of different methods to handle effluent from nuclear thermal propulsion system ground tests.
This report details the Science Fair Self-Help Development Program, which was initiated in a pilot project at three middle schools in Albuquerque, NM, during school year 1991-1992. The purpose of the program was to provide guidance to schools in developing their own parental and community resources into a sustainable support group whose major function would be to assist the school's science teachers and administration in all aspects of the science fair. The report documents the development of the Self-Help Program and the results of the pilot testing.
This document presents the quality assurance (QA) philosophy and procedures for analyses and report reviews used by the Performance Assessment Department of Sandia National Laboratories, which directly supports the Waste Isolation Pilot Plant (WIPP). Analysis procedures described herein will be incorporated into the Performance Assessment Analysis Quality Assurance Procedures (QAP 2-4), and report review procedures will be incorporated into QAP 2-5; both will apply to all Sandia and Sandia contractor activities related to performance assessment (except where the contractor has its own approved QA procedures). This report presents the philosophy behind the OA procedures, provides the standards adopted for performance assessment analysis and report review, discusses the implementation of these standards, and summarizes the software executive package, CAMCON, which aids in implementing the standards.
The choice of technologies for the delivery of very high bandwidth throughout a facility capable of ultimately achieving gigabits per second performance, is a crucial one for any high technology facility. The components of a high bandwidth delivery system include high performance sources and sinks in the form of central facilities (major mainframes, large file storage and specialized peripherals) and powerful, full bandwidth distributed local area networks (LANs). In order to deliver bandwidth among the sources and sinks, a ubiquitous inter-/intra-building cable plant consisting of single mode and multimode fiber as well as twisted pair copper is required. The selection of the ``glue`` to transport and interconnect the LANs with the central facility over the pervasive cable plant is the focus of this paper. A design philosophy for high performance communications systems is proposed. A description of the traditional problems that must be overcome to provide very high bandwidth beyond the narrow confines of a computer center is given. The advantages of ATM switching and SONET physical transport are explored in the structured design presentation. The applicability of Asynchronous Transfer Mode (ATM) switching (interconnection) and Synchronous Optical NETwork (SONET) (transport) for high bandwidth delivery is described using the environment and requirements of Sandia National Laboratories as a context to examine the suitability of those technologies. The synergy and utility of ATM and SONET in the campus network are explored. Other methods for distributing high data rates are compared and contrasted to ATM and SONET with respect to cable plant impact, reliability/availability, maintainability, and capacity. Sandia is implementing a standards based foundation utilizing a pervasive single mode fiber cable plant, SONET transport, and ATM switching to meet the goals of gigabit networking.
Aerospace components are often subjected to pyroshock events during flight and deployment, and must be qualified to this frequently severe environment. Laboratory simulation of pyroshock using a mechanically excited resonant fixture, has gained favor at Sandia for testing small (<8 inch cube) weapon components. With this method, each different shock environment required a different resonant fixture that was designed such that it`s response matched the environment. A new test method has been developed which eliminates the need to have a different resonant fixture for each test requirement. This is accomplished by means of a tunable resonant fixture that has a response which is adjustable over a wide frequency range. The adjustment of the fixture`s response is done in a simple and deterministic way. This report covers the first phase of this research, which includes design conception through fabrication and evaluation of hardware capable of testing components with up to a 10 inch {times} 10 inch base. This method will ultimately allow the testing of much larger items, perhaps as large as entire small satellites.