DOE has made a commitment to compliance with all applicable environmental regulatory requirements. In this respect, it is important to consider and design all tritium supply alternatives so that they can comply with these requirements. The management of waste is an integral part of this activity and it is therefore necessary to estimate the quantities and specific wastes that will be generated by all tritium supply alternatives. A thorough assessment of waste streams includes waste characterization, quantification, and the identification of treatment and disposal options. The waste assessment for APT has been covered in two reports. The first report was a process waste assessment (PWA) that identified and quantified waste streams associated with both target designs and fulfilled the requirements of APT Work Breakdown Structure (WBS) Item 5.5.2.1. This second report is an expanded version of the first that includes all of the data of the first report, plus an assessment of treatment and disposal options for each waste stream identified in the initial report. The latter information was initially planned to be issued as a separate Waste Treatment and Disposal Options Assessment Report (WBS Item 5.5.2.2).
Simulations with finite element models of well controlled impact experiments with x-cut quartz gauges have been performed with the transient electromechanics code SUBWAY. Comparisons of measured gauge output current with calculated output current were made for four fully-electroded gauge configurations, involving two different can spacings and potting materials. The observed good agreement between measured and calculated currents provides a basis for confidence in the basic capabilities of the code.
Given the low cost of petroleum crude, direct coal liquefaction is still not an economically viable process. The DOE objectives are to further reduce the cost of coal liquefaction to a more competitive level. In this project the primary focus is on the use of low-rank coal feedstocks. A particular strength is the use of process-derived liquids rather than model compound solvents. The original concepts are illustrated in Figure 1, where they are shown on a schematic of the Wilsonville pilot plant operation. Wilsonville operating data have been used to define a base case scenario using run {number_sign}263J, and Wilsonville process materials have been used in experimental work. The CAER has investigated: low severity CO pretreatment of coal for oxygen rejection, increasing coal reactivity and mg inhibiting the propensity for regressive reactions; the application of more active. Low-cost Fe and Mo dispersed catalysts; and the possible use of fluid coking for solids rejection and to generate an overhead product for recycle. CONSOL has investigated: oil agglomeration for coal ash rejection, for the possible rejection of ash in the recycled resid, and for catalyst addition and recovery; and distillate dewaxing to remove naphthenes and paraffins, and to generate an improved quality feed for recycle distillate hydrogenation. At Sandia, research has been concerned with the production of active hydrogen donor distillate solvent fractions produced by the hydrogenation of dewaxed distillates and by fluid coking via low severity reaction with H{sub 2}/CO/H{sub 2}O mixtures using hydrous metal oxide and other catalysts.
A stochastic representation of the lithologic units and associated hydrogeologic parameters of the potential high-level nuclear waste repository are developed for use in performance-assessment calculations, including the Total-System Performance Assessment for Yucca Mountain-SNL Second Iteration (TSPA-1993). A simplified lithologic model has been developed based on the physical characteristics of the welded and nonwelded units at Yucca Mountain. Ten hydrogeologic units are developed from site-specific data (lithologic and geophysical logs and core photographs) obtained from the unsaturated and saturated zones. The three-dimensional geostatistical model of the ten hydrogeologic units is based on indicator-coding techniques and improves on the two-dimensional model developed for TSPA91. The hydrogeologic properties (statistics and probability distribution functions) are developed from the results of laboratory tests and in-situ aquifer tests or are derived through fundamental relationships. Hydrogeologic properties for matrix properties, bulk conductivities, and fractures are developed from existing site specific data. Extensive data are available for matrix porosity, bulk density, and matrix saturated conductivity. For other hydrogeologic properties, the data are minimal or nonexistent. Parameters for the properties are developed as beta probability distribution functions. For the model units without enough data for analysis, parameters are developed as analogs to existing units. A relational, analytic approach coupled with bulk conductivity parameters is used to develop fracture parameters based on the smooth-wall-parallel-plate theory. An analytic method is introduced for scaling small-core matrix properties to the hydrogeologic unit scales.
Burnup verification measurements have been performed using the Fork system at Arkansas Nuclear One, Units 1 and 2, operated by Energy Operations, Inc. Passive neutron and gamma-ray measurements on individual spent fuel assemblies were correlated with the reactor records for burnup, cooling time, and initial enrichment. The correlation generates an internal calibration for the system in the form of a power law determined by a least squares fit to the neutron data. The values of the exponent in the power laws were 3.83 and 4.35 for Units 1 and 2, respectively. The average deviation of the reactor burnup records from the calibration determined from the measurements is a measure of the random error in the burnup records. The observed average deviations were 2.7% and 3.5% for assemblies at Units 1 and 2, respectively, indicating a high degree of consistency in the reactor records. Two non-standard assemblies containing neutron sources were studied at Unit 2. No anomalous measurements were observed among the standard assemblies at either Unit. The effectiveness of the Fork system for verification of reactor records is due to the sensitivity of the neutron yield to burnup, the self-calibration generated by a series of measurements, the redundancy provided by three independent detection systems, and the operational simplicity and flexibility of the design.
A pair of charge carriers can be bound within a common potential well produced by displacing atoms from their carrier-free equilibrium positions. These two self-trapped carriers together with the associated atomic-displacement pattern is referred to as a bipolaron. If the self-trapped carriers` wavefunction is primarily confined to a single structural unit (atom, bond or molecule), the bipolaron is termed small. If however the self-trapped carriers` wavefunction extends over multiple structural units, the bipolaron is called large. Small bipolarons form in crystals if the energy lowering due to the carriers` self-trapping exceeds the electronic-transfer energy associated with an electronic carrier`s intersite motion. Small-polaron and -bipolaron formation is also often induced by disorder. Interest in bipolarons focuses on situations in which they are energetically stable with respect to dissociating into two individual carriers. Stability is achieved when the additional lowering of the atomic-displacement-related energy arising from two carriers sharing a common site overwhelms their mutual Coulomb repulsion. Self-trapped carriers only move when the positions of the atoms whose displacements produce self-trapping change. When atoms move so as to shift small-polaronic self-trapped carriers between adjacent sites, changes of the self-trapped carriers` energies always exceed their intersite electronic transfer energy. Since small-polaronic self-trapped carriers thereby lose coherence as they move, their transport is described as hopping incoherently between localized states. This report discusses the electronic structure of boron carbides and describes features that make them ideal for studying small bipolaron hopping. The effect on conductivity is discussed.
This paper is written to document the SURFSCAN program. A large section of the code is devoted to error recovery. The heavy emphasis on error recovery allows unattended operation for extended periods. By combining error recovery with the use of control files, SURFSCAN has been operated for periods of several days with no operator intervention. At this time, the Surface Profilometer is a useful and productive tool in the Rock Mechanics Laboratory at Sandia National Laboratories/New Mexico. In the Rock Mechanics Laboratory we have been conducting studies of the normal and shear mechanical behavior of fractures and the flow of fluid through fractured rock formations. To estimate these properties, we need to know the average aperture size and surface texture of a fracture. These data may be obtained from surface profiles of mating pieces of rock. By scanning corresponding regions on two mating surfaces, the aperture size may be easily determined.
A fiberglass-reinforced plastic (FRP) pressure vessel containing sulfuric acid failed catastrophically in service. Preliminary investigations ruled out failure due to sabotage and chemical or mechanical overpressure. Subsequent examination of the fiber fracture surfaces and measurements of mirror radii indicated that fiber failure had occurred at stresses significantly below the fibers` expected strength. Further examination by scanning electron microscopy and energy dispersive spectroscopy indicated that the glass fibers had been exposed to sulfuric acid, a reagent that corrodes this type of glass and degrades its strength. Finite element analysis indicated stresses in an exposed region of the vessel that exceeded the strengths of the FRP during normal vessel operation. Numerous cracks were detected in this region using a vicinal optical illumination technique. We concluded that vessel failure was caused by progressive degradation and rupture of fibers starting at the outer surface of the FRP and extending inwards and laterally, until a crack of critical size was produced.
This report summarizes Sandia National Laboratories` participation in the fire modeling activities for the German Heiss Dampf Reaktor (HDR) containment building, under the sponsorship of the United States Nuclear Regulatory Commission. The purpose of this report is twofold: (1) to summarize Sandia`s participation in the HDR fire modeling efforts and (2) to summarize the results of the international fire modeling community involved in modeling the HDR fire tests. Additional comments, on the state of fire modeling and trends in the international fire modeling community are also included. It is noted that, although the trend internationally in fire modeling is toward the development of the more complex fire field models, each type of fire model has something to contribute to the understanding of fires in nuclear power plants.
This 1994 report contains data from routine radiological and nonradiological environmental monitoring activities. Summaries of significant environmental compliance programs in progress, such as National Environmental Policy Act documentation, environmental permits, environmental restoration, and various waste management programs for Sandia National Laboratories in Albuquerque, New Mexico, are included. The maximum off-site dose impact from air emissions was calculated to be 1.5 x 10{sup -4} millirem. The total population within a 50-mile radius of Sandia National Laboratories/New Mexico received an estimated collective dose of 0.012 person-rem during 1994 from the laboratories` operations. This report is prepared for the U.S. Department of Energy in compliance with DOE Order 5400.1.
A processed quartz sand (Wedron 510), mined from the St. Peter sandstone, has been characterized by a variety of chemical and physical methods for use as a reference porous media in transport model validation experiments. Wedron 510 sand was used in an intermediate-scale experiment involving migration of Ni, Li and Br through a 6-m high x 3-m diameter caisson. Ni and Li adsorption/desorption, and Li/Ni site-competition experiments yielded information on the importance of the trace mineral phases to adsorption of Li and Ni by the sand. The presence of an iron hydroxide coating similar to goethite on the sand grains is suggested by visual observation and leaching experiments. Kaolinite was identified by SEM and XRD as a significant trace mineral phase in the sand and occurs as small particles coating the sand grains. Quartz, the predominant constituent of the sand by weight, does not appear to contribute significantly to the adsorption properties of the sand. Qualitatively, the adsorption properties of the sand can be adequately modeled as a two-mineral system (goethite and kaolinite). The studies described in this report should provide a basis for understanding transport of Ni, Li and Br through porous media similar to the reference sand. Techniques were developed for obtaining parameter values for surface complexation and kinetic adsorption models for the sand and its mineral components. These constants can be used directly in coupled hydrogeochemical transport codes. The techniques should be useful for characterization of other natural materials and elements in high-level nuclear waste in support of coupled hydrogeochemical transport calculations for Yucca Mountain.
In this paper we apply a ``dual-transistor border-trap`` (DTBT) technique that combines high-frequency charge-pumping and lower-frequency threshold-voltage measurements to estimate bulk-oxide-trap, interface-trap, and border-trap densities in irradiated MOS transistors. This method takes advantage of the different time scales in which interface traps and border traps exchange charge with the Si to obtain an estimate of the density of faster border traps often mistaken for interface traps. Effects of slower border traps are also inferred from changes in the ``bulk`` oxide-trap charge density through switched-bias annealing. To our knowledge, this is the first time fast and slow border-trap effects have been separated quantitatively in MOS devices. Possible microstructures for fast and slow border traps are suggested.
The production of positive lithium ions using a lithium-fluoride-coated stainless steel anode in the particle beam fusion accelerator PBFA II is considered from both the experimental and theoretical points of view. It is concluded that the mechanism of Li{sup +} ion production is electric field desorption from the tenth-micron-scale crystallites which compose the columnar growth of the LiF thin film. The required electric field is estimated to be of the order of 5 MV/cm. An essential feature of the mechanism is that the crystallites are rendered electronically conducting through electron-hole pair generation by MeV electron bombardment of the thin film during the operation of the diode. It is proposed that the ion emission mechanism is an electronic conductivity analogue to that discovered by Rollgen for lithium halide crystallites which were rendered ionically conducting by heating to several hundred degrees Celsius. Since an electric field desorption mechanism cannot operate if a surface flashover plasma has formed and reduced the anode electric field to low values, the possibility of flashover on the lithium fluoride coated anode of the PBFA II Li{sup +} ion source is studied theoretically. It is concluded with near certainty that flashover does not occur.
Two-dimensional, heterogeneous, spatially correlated models of thermal conductivity and bulk density have been created for a representative, east-west cross section of Yucca Mountain, Nevada, using geostatistical simulation. The thermal conductivity models are derived from spatially correlated, surrogate material-property models of porosity, through a multiple linear-regression equation, which expresses thermal conductivity as a function of porosity and initial temperature and saturation. Bulk-density values were obtained through a similar, linear-regression relationship with porosity. The use of a surrogate-property allows the use of spatially much-more-abundant porosity measurements to condition the simulations. Modeling was conducted in stratigraphic coordinates to represent original depositional continuity of material properties and the completed models were transformed to real-world coordinates to capture present-day tectonic tilting and faulting of the material-property units. Spatial correlation lengths required for geostatistical modeling were assumed, but are based on the results of previous transect-sampling and geostatistical-modeling work.
The Mixed Waste Landfill Integrated Demonstration was tasked with demonstrating innovative technologies for the cleanup of chemical and mixed waste landfills that are representive of sites occurring throughout the DOE complex and the nation. The SEAMIST{trademark} inverting membrane deployment system has been used successfully at the Mixed Waste Landfill Integrated Demonstration (MWLID) for multipoint vapor sampling, pressure measurement, permeability measurement, sensor integration demonstrations, and borehole lining. Several instruments were deployed inside the SEAMIST{trademark}-lined boreholes to detect metals, radionuclides, moisture, and geologic variations. The liner protected the instruments from contamination, maintained support of the uncased borehole wall, and sealed the total borehole from air circulation. Recent activities included the installation of three multipoint vapor sampling systems and sensor integration systems in 100-foot-deep vertical boreholes. A long term pressure monitoring program has recorded barometric pressure effects at depth with relatively high spatial resolution. The SEAMIST{trademark} system has been integrated with a variety of hydrologic and chemical sensors for in-situ measurements, demonstrating its versatility as an instrument deployment system that allows easy emplacement and removal. Standard SEAMIST{trademark} vapor sampling systems were also integrated with state-of-the-art volatile organic compound analysis technologies. The results and status of these demonstration tests are presented.
One of the primary factors that influences our predictions of host-rock thermal response within a high level waste repository is how the waste stream`s represented in the models. In the context of thermal modeling, waste stream refers to an itemized listing of the type (pressurized-water or boiling-water reactor), age, burnup, and enrichment of the spent nuclear fuel assemblies entering the repository over the 25-year emplacement phase. The effect of package-by-package variations in spent fuel characteristics on predicted repository thermal response is the focus of this report. A three-year portion of the emplacement period was modeled using three approaches to waste stream resolution. The first assumes that each package type emplaced in a given year is adequately represented by average characteristics. For comparison, two models that explicitly account for each waste package`s individual characteristics were run; the first assuming a random selection of packages and the second an ordered approach aimed at locating the higher power output packages toward the center of the emplacement area. Results indicate that the explicit representation of packages results in hot and cold spots that could have performance assessment and design implications. Furthermore, questions are raised regarding the representativeness of average characteristics with respect to integrated energy output and the possible implications of a mass-based repository loading approach.
The response of underground structures and transportation facilities under various external loadings and environments is critical for human safety as well as environmental protection. Since quasi-brittle materials such as concrete and rock are commonly used for underground construction, the constitutive modeling of these engineering materials, including post-limit behaviors, is one of the most important aspects in safety assessment. From experimental, theoretical, and computational points of view, this report considers the constitutive modeling of quasi-brittle materials in general and concentrates on concrete in particular. Based on the internal variable theory of thermodynamics, the general formulations of plasticity and damage models are given to simulate two distinct modes of microstructural changes, inelastic flow and degradation of material strength and stiffness, that identify the phenomenological nonlinear behaviors of quasi-brittle materials. The computational aspects of plasticity and damage models are explored with respect to their effects on structural analyses. Specific constitutive models are then developed in a systematic manner according to the degree of completeness. A comprehensive literature survey is made to provide the up-to-date information on prediction of structural failures, which can serve as a reference for future research.
The Verification and Monitoring Options Study Project (VAMOS) was established to identify high-priority options for future vadose-zone environmental research in the areas of in-situ remediation monitoring, post-closure monitoring, and containment emplacement and verification monitoring. VAMOS examined projected needs not currently being met with applied technology in order to develop viable monitoring and verification research options. The study emphasized a compatible systems approach to reinforce the need for utilizing compatible components to provide user friendly site monitoring systems. To identify the needs and research options related to vadose-zone environmental monitoring and verification, a literature search and expert panel forums were conducted. The search included present drivers for environmental monitoring technology, technology applications, and research efforts. The forums included scientific, academic, industry, and regulatory environmental professionals as well as end users of environmental technology. The experts evaluated current and future monitoring and verification needs, methods for meeting these needs, and viable research options and directions. A variety of high-priority technology development, user facility, and technology guidance research options were developed and presented as an outcome of the literature search and expert panel forums.
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.