Eight alternative methods for approximating salt creep and disposal room closure in a multiphase flow model of the Waste Isolation Pilot Plant (WIPP) were implemented and evaluated: Three fixed-room geometries three porosity functions and two fluid-phase-salt methods. The pressure-time-porosity line interpolation method is the method used in current WIPP Performance Assessment calculations. The room closure approximation methods were calibrated against a series of room closure simulations performed using a creep closure code, SANCHO. The fixed-room geometries did not incorporate a direct coupling between room void volume and room pressure. The two porosity function methods that utilized moles of gas as an independent parameter for closure coupling. The capillary backstress method was unable to accurately simulate conditions of re-closure of the room. Two methods were found to be accurate enough to approximate the effects of room closure; the boundary backstress method and pressure-time-porosity line interpolation. The boundary backstress method is a more reliable indicator of system behavior due to a theoretical basis for modeling salt deformation as a viscous process. It is a complex method and a detailed calibration process is required. The pressure lines method is thought to be less reliable because the results were skewed towards SANCHO results in simulations where the sequence of gas generation was significantly different from the SANCHO gas-generation rate histories used for closure calibration. This limitation in the pressure lines method is most pronounced at higher gas-generation rates and is relatively insignificant at lower gas-generation rates. Due to its relative simplicity, the pressure lines method is easier to implement in multiphase flow codes and simulations have a shorter execution time.
A long-term assessment of the Waste Isolation Pilot Plant (WIPP) repository performance must consider the impact of gas generation resulting from the corrosion and microbial degradation of the emplaced waste. A multiphase fluid flow code, TOUGH2/EOS8, was adapted to model the processes of gas generation, disposal room creep closure, and multiphase (brine and gas) fluid flow, as well as the coupling between the three processes. System response to gas generation was simulated with a single, isolated disposal room surrounded by homogeneous halite containing two anhydrite interbeds, one above and one below the room. The interbeds were assumed to have flow connections to the room through high-permeability, excavation-induced fractures. System behavior was evaluated by tracking four performance measures: (1) peak room pressure; (2) maximum brine volume in the room; (3) total mass of gas expelled from the room; and (4) the maximum gas migration distance in an interbed. Baseline simulations used current best estimates of system parameters, selected through an evaluation of available data, to predict system response to gas generation under best-estimate conditions. Sensitivity simulations quantified the effects of parameter uncertainty by evaluating the change in the performance measures in response to parameter variations. In the sensitivity simulations, a single parameter value was varied to its minimum and maximum values, representative of the extreme expected values, with all other parameters held at best-estimate values. Sensitivity simulations identified the following parameters as important to gas expulsion and migration away from a disposal room: interbed porosity; interbed permeability; gas-generation potential; halite permeability; and interbed threshold pressure. Simulations also showed that the inclusion of interbed fracturing and a disturbed rock zone had a significant impact on system performance.
Reconsolidation of crushed rock salt is a phenomenon of great interest to programs studying isolation of hazardous materials in natural salt geologic settings. Of particular interest is the potential for disaggregated salt to be restored to nearly an impermeable state. For example, reconsolidated crushed salt is proposed as a major shaft seal component for the Waste Isolation Pilot Plant (WIPP) Project. The concept for a permanent shaft seal component of the WIPP repository is to densely compact crushed salt in the four shafts; an effective seal will then be developed as the surrounding salt creeps into the shafts, further consolidating the crushed salt. Fundamental information on placement density and permeability is required to ensure attainment of the design function. The work reported here is the first large-scale compaction demonstration to provide information on initial salt properties applicable to design, construction, and performance expectations. The shaft seals must function for 10,000 years. Over this period a crushed salt mass will become less permeable as it is compressed by creep closure of salt surrounding the shaft. These facts preclude the possibility of conducting a full-scale, real-time field test. Because permanent seals taking advantage of salt reconsolidation have never been constructed, performance measurements have not been made on an appropriately large scale. An understanding of potential construction methods, achievable initial density and permeability, and performance of reconsolidated salt over time is required for seal design and performance assessment. This report discusses fielding and operations of a nearly full-scale dynamic compaction of mine-run WIPP salt, and presents preliminary density and in situ (in place) gas permeability results.
For a number of years, robotics researchers have exploited hierarchical representations of geometrical objects and scenes in motion-planning, collision-avoidance, and simulation. However, few general techniques exist for automatically constructing them. We present a generic, bottom-up algorithm that uses a heuristic clustering technique to produced balanced, coherent hierarchies. Its worst-case running time is O(N{sup 2}logN), but for non-pathological cases it is O(NlogN), where N is the number of input primitives. We have completed a preliminary C++ implementation for input collections of 3D convex polygons and 3D convex polyhedra and conducted simple experiments with scenes of up to 12,000 polygons, which take only a few minutes to process. We present examples using spheres and convex hulls as hierarchy primitives.
This paper describes two methods for controlling the surface of a liquid in an open container as it is being carried by a robot arm. Both methods make use of the fundamental mode of oscillation and damping of the liquid in the container as predicted from a boundary element model of the fluid. The first method uses an infinite impulse response filter to alter an acceleration profile so that the liquid remains level except for a single wave at the beginning and end of the motion. The motion of the liquid is similar to that of a simple pendulum. The second method removes the remaining two surface oscillations by tilting the container parallel to the beginning and ending wave. A double pendulum model is used to determine the trajectory for this motion. Experimental results of a FANUC S-800 robot moving a 230 mm diameter hemispherical container of water are presented.
This paper formulates an algorithm for trajectory generation for two robots cooperating to perform an assembly task. Treating the two robots as a single redundant system, this paper derives two Jacobian matrices which relate the joint rates of the entire system to the relative motion of the grippers with respect to one another. The advantage of this formulation over existing methods is that a variety of secondary criteria can be conveniently satisfied using motion in the null-space of the relative Jacobian. This paper presents methods for generating dual-arm joint trajectories which perform assembly tasks while at the same time avoiding obstacles and joint limits, and also maintaining constraints on the absolute position and orientation of the end-effectors.
Rock properties in volcanic units at Yucca Mountain are controlled largely by relatively deterministic geologic processes related to the emplacement, cooling, and alteration history of the tuffaceous lithologic sequence. Differences in the lithologic character of the rocks have been used to subdivide the rock sequence into stratigraphic units, and the deterministic nature of the processes responsible for the character of the different units can be used to infer the rock material properties likely to exist in unsampled regions. This report proposes a quantitative, theoretically justified method of integrating interpretive geometric models, showing the three-dimensional distribution of different stratigraphic units, with numerical stochastic simulation techniques drawn from geostatistics. This integration of soft, constraining geologic information with hard, quantitative measurements of various material properties can produce geologically reasonable, spatially correlated models of rock properties that are free from stochastic artifacts for use in subsequent physical-process modeling, such as the numerical representation of ground-water flow and radionuclide transport. Prototype modeling conducted using the GSLIB-Lynx Integration Module computer program, known as GLINTMOD, has successfully demonstrated the proposed integration technique. The method involves the selection of stratigraphic-unit-specific material-property expected values that are then used to constrain the probability function from which a material property of interest at an unsampled location is simulated.
To create an information system, we employ NIAM (Natural language Information Analysis Methodology). NIAM supports the goals of both the customer and the analyst completely understanding the information. We use the customer`s own unique vocabulary, collect real examples, and validate the information in natural language sentences. Examples are discussed from a successfully implemented information system.
The Burn Diagnostic and Laser Debridement project, CRADA Number SC93/01177 between Sandia and Wellman Laboratories of Photomedicine, will develop a prototype system for human trials of burn injury treatment using optical-based diagnostics and laser debridement. This quarterly progress report for July through September 1995 combines contributions from all team members on the project. The primary emphasis this quarter was completion of the Prototype Design Review. The review was conducted in two sessions, first at Sandia and second at Wellman. The objectives were to validate the requirements, compare the design intent with the stated requirements, critique the design, and conclude with a rating of acceptable, conditionally acceptable, or unacceptable. Although the design was rated conditionally acceptable at Sandia, the Wellman researchers felt too many issues were unresolved and therefore could not support that rating. The authors have initiated a plan to rapidly reach consensus on the remaining unresolved requirement issues so that construction of the Prototype II system can begin.
This report documents US Department of Energy (DOE)-funded activities that have adapted the US Navy`s Surface Towed Ordnance Locator System (STOLS) to meet DOE needs for a ``... better, faster, safer and cheaper ...`` system for characterizing inactive hazardous waste sites. These activities were undertaken by Sandia National Laboratories (Sandia), the Naval Research Laboratory, Geo-Centers Inc., New Mexico State University and others under the title of the Magnetometer Towed Array (MTA).
Traditional encryption, which protects messages from prying eyes, has been used for many decades. The present concepts of encryption are built from that heritage. Utilization of modern software-based encryption techniques implies much more than simply converting files to an unreadable form. Ubiquitous use of computers and advances in encryption technology coupled with the use of wide-area networking completely changed the reasons for utilizing encryption technology. The technology demands a new and extensive infrastructure to support these functions. Full understanding of these functions, their utility and value, and the need for an infrastructure, takes extensive exposure to the new paradigm. This paper addresses issues surrounding the establishment and operation of a key management system (i.e., certification authority) that is essential to the successful implementation and wide-spread use of encryption.
The reactor facilities at Sandia National Laboratories have hosted a number of reactors and critical experiments. A critical experiment is currently being done to support an ongoing investigation by the US Department of Energy of the consequences of taking fuel burnup into account in the design of spent fuel transportation packages. A series of experiments, collectively called the Spent Fuel Safety Experiment (SFSX), has been devised to provide integral benchmarks for testing computer-generated predictions of spent fuel behavior. A set of experiments is planned in which sections of unirradiated fuel rods are interchanged with similar sections of spent pressurized water reactor (PWR) fuel rods in a critical assembly. By determining the critical size of the arrays, one can obtain benchmark data for comparison with criticality safety calculations. The SFSX provides a direct measurement of the reactivity effects of spent PWR fuel using a well-characterized, spent fuel sample. The SFSX also provides an experimental measurement of the end-effect, i.e., the reactivity effect of the variation of the burnup profile at the ends of PWR fuel rods. The design of the SFSX is optimized to yield accurate benchmark measurements of the effects of interest, well above experimental uncertainties.
This paper defines a class of evolutionary algorithms called evolutionary pattern search algorithms (EPSAs) and analyzes their convergence properties. This class of algorithms is closely related to evolutionary programming, evolutionary strategie and real-coded genetic algorithms. EPSAs are self-adapting systems that modify the step size of the mutation operator in response to the success of previous optimization steps. The rule used to adapt the step size can be used to provide a stationary point convergence theory for EPSAs on any continuous function. This convergence theory is based on an extension of the convergence theory for generalized pattern search methods. An experimental analysis of the performance of EPSAs demonstrates that these algorithms can perform a level of global search that is comparable to that of canonical EAs. We also describe a stopping rule for EPSAs, which reliably terminated near stationary points in our experiments. This is the first stopping rule for any class of EAs that can terminate at a given distance from stationary points.
This paper examines the effects of relaxed synchronization on both the numerical and parallel efficiency of parallel genetic algorithms (GAs). We describe a coarse-grain geographically structured parallel genetic algorithm. Our experiments show that asynchronous versions of these algorithms have a lower run time than-synchronous GAs. Furthermore, we demonstrate that this improvement in performance is partly due to the fact that the numerical efficiency of the asynchronous genetic algorithm is better than the synchronous genetic algorithm. Our analysis includes a critique of the utility of traditional parallel performance measures for parallel GAs, and we evaluate the claims made by several researchers that parallel GAs can have superlinear speedup.
The preliminary criticality analysis that was done suggests that the possibility of achieving critical conditions cannot be easily ruled out without looking at the geochemical process of assembly or the dynamics of the operation of a critical assembly. The evaluation of a critical assembly requires an integrated, consistent approach that includes evaluating the following: (1) the alteration rates of the layers of the container and spent fuel, (2) the transport of fissile material or neutron absorbers, and (3) the assembly mechanisms that can achieve critical conditions. The above is a non-trivial analysis and preliminary work suggests that with the loading assumed, enough fissile mass will leach from the HEU multi-purpose canisters to support a criticality. In addition, the consequences of an unpressurized Oklo type criticality would be insignificant to the performance of an unsaturated, tuff repository.
Burnup verification measurements have been performed using the Fork system at the Oconee Nuclear Station of Duke Power Company, and 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 least squares fit to the neutron data. 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 ranged from 2.2% to 3.5% for assemblies at the three reactor sites, indicating a high degree of consistency in the reactor records. Anomalous measurements were also observed but could be explained by the presence of neutron sources in the assemblies. 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.
The properties and performance of a ceramic component is determined by a combination of the materials from which it was fabricated and how it was processed. Most ceramic components are manufactured by dry pressing a powder/binder system in which the organic binder provides formability and green compact strength. A key step in this manufacturing process is the removal of the binder from the powder compact after pressing. The organic binder is typically removed by a thermal decomposition process in which heating rate, temperature, and time are the key process parameters. Empirical approaches are generally used to design the burnout time-temperature cycle, often resulting in excessive processing times and energy usage, and higher overall manufacturing costs. Ideally, binder burnout should be completed as quickly as possible without damaging the compact, while using a minimum of energy. Process and computational modeling offer one means to achieve this end. The objective of this study is to develop an experimentally validated computer model that can be used to better understand, control, and optimize binder burnout from green ceramic compacts.
The Department of Energy`s Office of Materials Disposition (MD) is analyzing long-term storage and disposition options for fissile materials, preparing a Programmatic Environmental Impact Statement (PEIS), preparing for a Record of Decision (ROD) regarding this material, and conducting other related activities. A primary objective of this program is to support U.S. nonproliferation policy by reducing major security risks. Particular areas of concern are the acquisition of this material by unauthorized persons and preventing the reintroduction of the material for use in weapons. This paper presents some of the issues, definitions, and assumptions addressed by the Safeguards and Security Project Team in support of the Fissile Materials Disposition Program (FMDP). The discussion also includes some preliminary ideas regarding safeguards and security criteria that are applicable to the screening of disposition options.
The Department of Energy has defined a safeguards system to be an integrated system of physical protection, material accounting and material control subsystems designed to deter, prevent, detect, and respond to unauthorized possession, use, or sabotage of SNM. In practice, safeguards involve the development and application of techniques and procedures dealing with the establishment and continued maintenance of a system of activities. The system must also include administrative controls and surveillance to assure that the procedures and techniques of the system are effective and are being carried out. The control of nuclear material is critical to the safeguarding of nuclear materials within the United States. The U.S. Department of Energy includes as part of material control four functional performance areas. They include access controls, material surveillance, material containment and detection/assessment. This paper will address not only these areas but also the relationship between material control and other safeguards and security functions.
A series of static overpressurization tests of scale models of nuclear containment structures is being conducted by Sandia National Laboratories for the Nuclear Power Engineering Corporation of Japan and the U.S. Nuclear Regulatory Commission. At present, two tests are being planned: a test of a model of a steel containment vessel (SCV) that is representative of an improved, boiling water reactor (BWR) Mark II design; and a test of a model of a prestressed concrete containment vessel (PCCV). This paper discusses plans and the results of a preliminary investigation of the instrumentation of the PCCV model. The instrumentation suite for this model will consist of approximately 2000 channels of data to record displacements, strains in the reinforcing steel, prestressing tendons, concrete, steel liner and liner anchors, as well as pressure and temperature. The instrumentation is being designed to monitor the response of the model during prestressing operations, during Structural Integrity and Integrated Leak Rate testing, and during test to failure of the model. Particular emphasis has been placed on instrumentation of the prestressing system in order to understand the behavior of the prestressing strands at design and beyond design pressure levels. Current plans are to place load cells at both ends of one third of the tendons in addition to placing strain measurement devices along the length of selected tendons. Strain measurements will be made using conventional bonded foil resistance gages and a wire resistance gage, known as a {open_quotes}Tensmeg{close_quotes}{reg_sign} gage, specifically designed for use with seven-wire strand. The results of preliminary tests of both types of gages, in the laboratory and in a simulated model configuration, are reported and plans for instrumentation of the model are discussed.
The dynamic behavior of laser-accelerator flyers has been studied using high-speed streak imaging in combination with stop motion microphotography. With very thin targets, melting and plasma penetration of the flyer material occur in rapid sequence. The time delay from the onset of motion to flyer breakup increases with flyer thickness and decreasing incident energy. Flyer materials examined include pure aluminum (0.25-2.6 {mu}m thick) and composite targets (0.5-2.0 {mu}m thick) containing an insulating layer of aluminum oxide. While flyer breakup is observed in both types of material, the Al{sub 2}O{sub 3} barrier significantly delays the deleterious effects of deep thermal diffusion.
Charge-Induced Voltage Alteration (CIVA), Light-Induced Voltage Alteration, (LIVA), and Low Energy CIVA (LECIVA) are three new failure analysis imaging techniques developed to quickly localize defects on ICs. All three techniques utilize the voltage fluctuations of a constant current power supply as an electron or photon beam is scanned across an IC. CIVA and LECIVA yield rapid localization of open interconnections on ICs. LIVA allows quick localization of open-circuited and damaged semiconductor junctions. LIVA can also be used to image transistor logic states and can be performed from the backside of ICs with an infrared laser source. The physics of signal generation for each technique and examples of their use in failure analysis are described.
The solubility of Np(V) was measured in NaCl solutions ranging from 0.30 to 5.6 molal at room temperature ({approximately}21 {plus_minus} 2{degrees}C). Experiments were conducted from undersaturation and allowed to equilibrate in a CO{sub 2}-free environment for 37 days. The apparent solubility products varied with NaCl concentration and were between 10{sup -9} and 10{sup -8} mol{sup 2}{sm_bullet}L{sup -2}. Using the specific ion interaction theory (SIT), the log of the solubility product of NpO{sub 2}OH(am) at infinite dilution was found to be - 8.79 {plus_minus} 0.12. The interaction coefficient, {epsilon}(NpO{sub 2}{sup +} - Cl{sup -}), was found to be (0.08 {plus_minus} 0.05).
Citrate is among the organic anions that are expected to be present in the wastes planned for deposition in the Waste Isolation Pilot Plant repository. In this study, a solvent extraction method has been used to measure the stability constants of Thorium(IV)[Th(IV)] with citrate anions in aqueous solutions with (a) NaClO{sub 4} and (b) NaCl as the background electrolytes. The ionic strengths were varied up to 5 m (NaCl) and 14 m (NaClO{sub 4}). The data from the NaClO{sub 4} solutions at varying pH values were used to calculate the hydrolysis constants for formation of Th(OH){sup 3+} at the different ionic strengths.
The acid dissociation constants, pK{sub a}, and the stability constants for NpO{sub 2}{sup +} and UO{sub 2}{sup 2+} have been measured for certain organic ligands [acetate, {alpha}-hydroxyisobutyrate, lactate, ascorbate, oxalate, citrate, EDTA, 8-hydroxyquinoline, 1, 10-phenanthroline, and thenoyltrifluoroacetone] in 5 m (NaCl) ionic strength solution. The pK{sub a} values were determined by potentiometry or spectrometry. These methods, as well as solvent extraction with {sup 233}U and {sup 237}Np radiotracers, were used to measure the stability constants of the 1:1 and 1:2 complexes of dioxo cations. These constants were used to estimate the concentrations required to result in 10 % competition with hydrolysis in the 5 m NaCl solution. Such estimates are of value in assessing the solubility from radioactive waste of AnO{sub 2}{sup +} and AnO{sub 2}{sup 2+} in brine solutions in contact with nuclear waste in a salt-bed repository.
The complexation of Am(III) by oxalate has been investigated in solutions of NaClO{sub 4} up to 9.0 M ionic strength at 25{degrees}C. The dissociation constants of oxalic acid were determined by potentiometric titration, while the stability constants of the Am(III)-oxalate complexation were measured by the solvent extraction technique. A thermodynamic model was constructed to predict the apparent equilibrium constants at different ionic strengths by applying the Pitzer equation using parameters for the Na{sup +}-HOx{sup -}, Na{sup +}-Ox{sup -}, AmOx{sup +}-ClO{sub 4}{sup -}, and Na{sup +}-Am(Ox){sub 2}{sup -} interactions obtained by fitting the data.
Piezoelectric polymer stress gauges in copper fixtures were used with te Sandia 2.5-inch bore gas gun to obtain time-resolved pressure measurements for two polytetrafluoroethylene powders having significantly different particle morphologies. The powders had approximate average particle sizes of 534 microns and 28 microns, respectively, and scanning electron microscopy revealed differences in the appearances of representative particle surfaces. The range of input stresses was from 0.13 GPa to 2.81 GPa, and the initial densities were 57% of the solid density. The ``crush strength`` (pressure required to compress the porous compact to solid density) was close to 1.0 GPa for the coarse material as compared to 0.6 GPa for the finer material. At an input stress of about 0.6 GPa, the risetime of the propagated stress waves in the coarse material was approximately 240 nsec compared to 50 nsec for the finer material. These measurements show the strongly rate-dependent deformation of the powders and that particle morphology has a significant effect on the shock compression.
Sandia National Laboratory`s PV System Components Department performs comprehensive failure analysis of photovoltaic modules after extended field exposure at various sites around the world. A full spectrum of analytical techniques are used to help identify the causes of degradation. The techniques are used to make solder fatigue life predictions for PV concentrator modules, identify cell damage or current mismatch, and measure the adhesive strength of the module encapsulant.
The Manufacturing Technologies Center is an integral part of Sandia National Laboratories, a multiprogram engineering and science laboratory, operated for the Department of Energy (DOE) with major facilities at Albuquerque, New Mexico, and Livermore, California. Our Center is at the core of Sandia`s Advanced Manufacturing effort which spans the entire product realization process.
We present two new techniques that enhance conventional focused ion beam (FIB) system capabilities for integrated circuit (IC) analysis: in situ electrical biasing and voltage contrast imaging. We have used in situ electrical biasing to enable a number of advanced failure analysis applications including (1) real time evaluation of device electrical behavior during milling and deposition, (2) verification of IC functional modifications without removal from the FIB system, and (3) ultraprecision control for cross sectioning of deep submicron structures, such as programmed amorphous silicon antifuses. We have also developed FIB system voltage contrast imaging that can be used for a variety of failure analysis applications. The use of passive voltage contrast imaging for defect localization and for navigation on planarized devices will be illustrated. In addition, we describe new, biased voltage contrast imaging techniques and provide examples of their application to the failure analysis of complex ICs. We discuss the necessary changes in system operating parameters to perform biased voltage contrast imaging.
In fabricating lead zirconate titanate (PZT) films for nonvolatile memories and decoupling capacitors, various deposition methods have been investigated. Each can produce films with acceptable dielectric and ferroelectric properties, but sol-gel methods offer excellent control of film stoichiometry and coating uniformity. The sol-gel approaches for PZT film fabrication fall into two categories: processes that use 2-methoxyethanol as a solvent, and processes that use chelating agents, such as acetic acid, for reducing the hydrolysis sensitivity of the alkoxide compounds. Due to concerns about the toxicity of 2-methoxyethanol, we have concentrated on the second category. It was found that, in addition to reducing the hydrolysis sensitivity, the chelating agents serves to define the processing behavior of the films: film consolidation after deposition and densification and crystallization during heat treatment. This paper discusses the relations between precursor structure (reactions between chelating agents and the metal alkoxide starting reagents) and film consolidation, densification, and crystallization.
A mathematical formulation is presented for describing the transport of air, water, NAPL, and energy through porous media. The development follows a continuum mechanics approach. The theory assumes the existence of various average macroscopic variables which describe the state of the system. Balance equations for mass and energy are formulated in terms of these macroscopic variables. The system is supplemented with constitutive equations relating fluxes to the state variables, and with transport property specifications. Specification of phase equilibrium criteria, various mixing rules and thermodynamic relations completes the system of equations. A numerical simulation scheme based on finite-differences is described.
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.