Groundwater travel time (GWTT) calculations will play an important role in addressing site-suitability criteria for the potential high-level nuclear waste repository at Yucca Mountain,Nevada. In support of these calculations, Preliminary assessments of the candidate codes and models are presented in this report. A series of benchmark studies have been designed to address important aspects of modeling flow through fractured media representative of flow at Yucca Mountain. Three codes (DUAL, FEHMN, and TOUGH 2) are compared in these benchmark studies. DUAL is a single-phase, isothermal, two-dimensional flow simulator based on the dual mixed finite element method. FEHMN is a nonisothermal, multiphase, multidimensional simulator based primarily on the finite element method. TOUGH2 is anon isothermal, multiphase, multidimensional simulator based on the integral finite difference method. Alternative conceptual models of fracture flow consisting of the equivalent continuum model (ECM) and the dual permeability (DK) model are used in the different codes.
To assess the influence of mountain-scale thermal property model variations on predicted host-rock thermal response, a series of heat conduction calculations were run using a representative two-dimensional cross section of Yucca Mountain. The effects of modeled geologic structure were evaluated through comparisons of results from a single-material, homogeneous model with those from a uniformly layered model, a discontinuous sloping-layered model, and a geo-statistical realization of thermal properties. Comparisons indicate that assumed geologic structure can result in up to a 24{degrees}C difference in predicted temperature response. Further, thermal simulations of the method used to analyze geostatistical realizations of thermal properties shows promise as an efficient means of capturing geologic structure without the complexities of intricate finite element meshing. The functional representation of two thermal property models were also investigated. The first examines the effect of using a weighting scheme to define properties for a single, homogenous material model. The second investigates the impact of thermal property temperature dependence on predicted response. As with the investigation of geologic structure, noticeable differences in predicted temperatures (up to 29{degrees}C) were found to result.
This is a second annual report since the University Center of Excellence for Photovoltaics Research and Education was established at Georgia Tech. The major focus of the center is crystalline silicon, and the mission of the Center is to improve the fundamental understanding of the science and technology of advanced photovoltaic devices and materials, to fabricate high-efficiency cells, and develop low-cost processes, to provide training and enrich the equational experience of students in this field, and to increase US competitiveness by providing guidelines to industry and DOE to achieve cost-effective and high-efficiency photovoltaic devices. This report outlines the work of the Center from July 1993--June 1994.
A five watt pseudo chip in the middle of a SEM-X circuit card was tested with various heat conduction paths in a satellite type electronic box while mounted in a vacuum chamber. Previous tests showed low temperature differentials with the use of circuit board clamps. Flight hardware with thin box walls, low mass module frames, and thin heat covers were tested to determine the temperature differential at 5.0 watts as well as at lower powers. The smallest temperature differential was 23 degrees Celsius between the 5 watt pseudo chip and the cold plate.
This report summarizes the environmental surveillance activities conducted by Sandia National Laboratories, the US Environmental Protection Agency, and Kirk-Mayer, Inc., for the Tonopah Test Range operated by Sandia National Laboratories. Sandia National Laboratories` responsibility for environmental surveillance results extends to those activities performed by Sandia National Laboratories or under its direction. Results from other environmental surveillance activities are included to provide a measure of completeness in reporting. Other environmental compliance programs such as the National Environmental Policy Act of 1969, environmental permits, and environmental restoration and waste management programs are also included in this report, prepared for the US Department of Energy (DOE) in compliance with DOE Order 5400. 1.
A popular three-dimensional mesh generation scheme is to start with a quadrilateral of the surface of a volume, and then attempt to fill the interior of volume with hexahedra, so that the hexahedra touch the surface in exactly the given quadrilaterals. Folklore has maintained that there are many quadrilateral meshes for which no such compatible hexahedral mesh exists. In this paper we give an existence proof which contradicts this folklore: A quadrilateral mesh need only satisfy some very weak conditions for there to exist a compatible hexahedral mesh. For a volume that is topologically a ball, any quadrilateral mesh composed of an even number of quadrilaterals admits a compatible hexahedral mesh. We extend this to volumes of higher genus: There is a construction to reduce to the ball case if and only if certain cycles of edges are even.
This paper describes a product realization process developed and demonstrated at Sandia by the A-PRIMED (Agile Product Realization for Innovative Electro MEchanical Devices) project that integrates many of the key components of ``agile manufacturing`` into a complete, design-to-production process. Evidence indicates that the process has reduced the product realization cycle and assured product quality. Products included discriminators for a robotic quick change adapter and for an electronic defense system. These discriminators, built using A-PRIMED, met random vibration requirements and had life cycles that far surpass the performance obtained from earlier efforts.
Encryption performance, in terms of bits per second encrypted, has not scaled well as network performance has increased. The authors felt that multiple encryption modules operating in parallel would be the cornerstone of scalable encryption. One major problem with parallelizing encryption is ensuring that each encryption module is getting the proper portion of the key sequence at the correct point in the encryption or decryption of the message. Many encryption schemes use linear recurring sequences, which may be generated by a linear feedback shift register. Instead of using a linear feedback shift register, the authors describe a method to generate the linear recurring sequence by using parallel decimated sequences, one per encryption module. Computing decimated sequences can be time consuming, so the authors have also described a way to compute these sequences with logic gates rather than arithmetic operations.
A-PRIMED (Agile Product Realization for Innovative Electro MEchanical Devices) demonstrated new product development in24 days accompanied by improved product quality, through ability enabling technologies. A concurrent engineering communications infrastructure was developed that provided electronic data communications, information access, enterprise integration of computers and applications, and collaborative work tools. This paper describes how A-PRIMED did it through attention to technologies, processes, and people.
Laboratory-scale heater experiments are Proposed to observe thermohydrologic Processes in tuffaceous rock using existing equipment and x-ray imaging techniques. The purpose of the experiments is to gain understanding of the near-field behavior and thermodynamic environment surrounding a heat source. As a prelude to these experiments, numerical simulations are performed to determine design-related parameters such as optimal heating power and heating duration. In addition, the simulations aid in identifying and understanding thermal processes and mechanisms that may occur under a variety of experimental conditions. Results of the simulations show that convection may play an important role in the heat transfer and thermodynamic environment of the heater if the Rayleigh-Darcy number exceeds a critical value (= 10 for the laboratory experiments) depending on the type of backfill material within the annulus (or drift).
This report contains the guidance Functional Requirements for an Integrated Intrusion Detection and Access Control Annunciator System, and survey results of selected commercial systems. The survey questions were based upon the functional requirements; therefore, the results reflect which and sometimes how the guidance recommendations were met.
A combined laboratory and field investigation was carried out to determine the extent of coring-induced damage done to samples cored from Marker Bed 139 at the WIPP site. Coring-induced damage, if present, has the potential to significantly change the properties of the material used for laboratory testing relative to the in situ material properties, resulting in misleading conclusions. In particular, connected, crack-like damage could make the permeability of cored samples orders of magnitude greater than the in situ permeabilities. Our approach compared in situ velocity and resistivity measurements with laboratory measurements of the same properties. Differences between in situ and laboratory results could be attributed to differences in the porosity due to cracks. The question of the origin of the changes could not be answered directly from the results of the measurements. Pre-existing cracks, held closed by the in situ stress, could open when the core was cut free, or new cracks could be generated by coring-induced damage. We used core from closely spaced boreholes at three orientations (0{degree}, {plus_minus}45{degrees} relative to vertical) to address the origin of cracks. The absolute orientation of pre-existing cracks would be constant, independent of the borehole orientation. In contrast, cracks induced by coring were expected to show an orientation dependent on that of the source borehole.
The Department of Energy (DOE) has shutdown many production reactors; the Department has begun a major effort to also shutdown a wide variety of other nuclear facilities. Because so many facilities are being closed, it is necessary to place many of them into a safe- storage status, i.e., deactivation, before conducting decommissioning- for perhaps as long as 20 years. The challenge is to achieve this safe-storage condition in a cost-effective manner while remaining in compliance with applicable regulations. The DOE Office of Environmental Management, Office of Transition and Management, commissioned a lessons-learned study of commercial experience with safe storage and decommissioning. Although the majority of the commercial experience has been with reactors, many of the lessons learned presented in this document can provide insight into transitioning challenges that Will be faced by the DOE weapons complex.
The solubility of Th(IV) hydrous oxide was studied in concentrated 4m and 6m NaCl solutions as well as in MgCl[sub 2] solutions ranging in concentration from 1m to 3m over a broad range of hydrogen ion concentrations. The observed solubilities in all solutions showed the same trend as observed previously of higher solubilities at early equilibration times, usually 7 to 8 days, followed by decreases in solubility with time as the precipitates aged. The trend of decreasing solubility with time was more pronounced in NaCl solutions than in MgCl[sub 2] solutions. The observed ThO[sub 2](am) solubilities in concentrated NaCl solutions (i.e., 4m and 6m) were lower than previously reported solubilities in more dilute NaCl solutions (i.e., < 3M NaCl). The results in MgCl[sub 2] were similar in all solutions regardless of the MgCl[sub 2] concentration. Current thermodynamic models for the solubility of hydrous thorium, oxide in chloride solutions, which primarily describe only aqueous Th[sup 4+]-Cl[sup -] ion-interactions, predicted higher solubilities than observed in 4 and 6m NaCl as well as in all MgCl[sub 2] solutions. An improved aqueous thermodynamic model, which includes ion-interaction parameters for like charged species, is proposed to explain these results.
In the sol-gel processing of ceramic thin films it has been frequently noted that the processing behavior, microstructure and properties of the films are dependent on the nature of the coating solution. In an attempt to understand such processing-property relationships, we have systematically investigated the effects of precursor nature on thin film densification and crystallization for ZrO2 and TiO2 thin films. Metal alkoxide starting compounds, e.g., zirconium (IV) n-butoxide n-butanol and titanium (IV) i-propoxide, were reacted with acetic acid and 2,4-pentanedione to prepare coating solutions for thin film deposition. The use of these ligands resulted in solution oligomeric species of different nature. Studies of thin film processing indicated that film processing characteristics, i.e., consolidation, densification and crystallization, were strongly dependent on solution precursor nature. Ligand steric size, pyrolysis behavior, extent of modification, and precursor reactivity were found to be key variables in controlling film processing.
This paper theoretically compares the performance of simulated annealing and evolutionary algorithms. Our main result is that under mild conditions a wide variety of evolutionary algorithms can be shown to have greater performance than simulated annealing after a sufficiently large number of function evaluations. This class of EAs includes variants of evolutionary strategie and evolutionary programming, the canonical genetic algorithm, as well as a variety of genetic algorithms that have been applied to combinatorial optimization problems. The proof of this result is based on a performance analysis of a very general class of stochastic optimization algorithms, which has implications for the performance of a variety of other optimization algorithm.
This paper describes an application where transportation logistics and simulation tools are integrated to create a modeling environment for transportation planning. The Transportation Planning Model (TPM) is a tool developed for the Department of Energy (DOE) to aid in the long-term planning of their transportation resources. The focus of the tool is to aid DOE and Sandia National Laboratory analysts in the planning of future fleet sizes, driver and support personnel sizes, base site locations, and resource balancing among the base sites. The design approach is to develop a rapid modeling environment which integrates graphical user interfaces, logistics optimizing tools, and simulation modeling. Using the TPM an analyst can easily set up a shipment scenario and perform multiple ``What If`` evaluations. The TPM has been developed on personal computers using commercial off-the-shelf software tools under the WINDOW{reg_sign} operating environment.
Field emission flat panel displays place new demands on the performance of cathodoluminescent phosphors. In particular, such phosphors must be efficient at lower voltages (ca. 100-1000 V), and must withstand higher current densities than are present on cathode ray tube screens. ZnO:Zn has been studied extensively as a low-voltage phosphor, but problems such as poor chromatic saturation and temperature sensitivity of emission remain. In this work the use of terbium-doped garnet phases such as yttrium aluminum garnet (YAG) and gadolinium gallium garnet (GGG) as low voltage green-emitting phosphors is evaluated. Hydrothermal synthesis yields well-faceted YAG grains with particle diameters of less than 1 {mu}m. Cathodoluminescent efficiency at a particular voltage was not affected by synthetic route, though the hydrothermally synthesized material was less susceptible to damage at high power densities. An efficiency of 3.5 lm/W was observed for GGG:Tb at 800 V. Deposition of the phosphors onto conducting screens increased their efficiencies at very low voltages (< 200 V). These materials may be considered alternatives to reduced zinc oxide as green-emitting phosphors.
The potential exists in a nuclear reactor core melt severe accident for molten core debris to be dispersed under high pressure into the containment building. If this occurs, the set of phenomena that result in the transfer of energy to the containment atmosphere and its surroundings is referred to as direct containment heating (DCH). Because of the potential for DCH to lead to early containment failure, the U.S. Nuclear Regulatory Commission (USNRC) has sponsored an extensive research program consisting of experimental, analytical, and risk integration components. An important element of the analytical research has been the development and assessment of direct containment heating models in the CONTAIN code. This report documents the DCH models in the CONTAIN code. DCH models in CONTAIN for representing debris transport, trapping, chemical reactions, and heat transfer from debris to the containment atmosphere and surroundings are described. The descriptions include the governing equations and input instructions in CONTAIN unique to performing DCH calculations. Modifications made to the combustion models in CONTAIN for representing the combustion of DCH-produced and pre-existing hydrogen under DCH conditions are also described. Input table options for representing the discharge of debris from the RPV and the entrainment phase of the DCH process are also described. A sample calculation is presented to demonstrate the functionality of the models. The results show that reasonable behavior is obtained when the models are used to predict the sixth Zion geometry integral effects test at 1/10th scale.
Researchers contend that composite repairs (or structural reinforcement doublers) offer numerous advantages over metallic patches including corrosion resistance, light weight, high strength, elimination of rivets, and time savings in installation. Their use in commercial aviation has been stifled by uncertainties surrounding their application, subsequent inspection and long-term endurance. The process of repairing or reinforcing airplane structures is time consuming and the design is dependent upon an accompanying stress and fatigue analysis. A repair that is too stiff may result in a loss of fatigue life, continued growth of the crack being repaired, and the initiation of a new flaw in the undesirable high stress field around the patch. Uncertainties in load spectrums used to design repairs exacerbates these problems as does the use of rivets to apply conventional doublers. Many of these repair or structural reinforcement difficulties can be addressed through the use of composite doublers. Primary among unknown entities are the effects of non-optimum installations and the certification of adequate inspection procedures. This paper presents on overview of a program intended to introduce composite doubler technology to the US commercial aircraft fleet. In this project, a specific composite application has been chosen on an L-1011 aircraft in order to focus the tasks on application and operation issues. Through the use of laboratory test structures and flight demonstrations on an in-service L-1011 airplane, this study is investigating composite doubler design, fabrication, installation, structural integrity, and non-destructive evaluation. In addition to providing an overview of the L-1011 project, this paper focuses on a series of fatigue and strength tests which have been conducted in order to study the damage tolerance of composite doublers. Test results to-date are presented.