VICTORIA is a mechanistic computer code that treats fission product behavior in the reactor coolant system during a severe accident. During an accident, fission products that deposit on structural surfaces produce heat loads that can cause fission products to revaporize and possibly cause structures, such as a pipe, to fail. This mechanism had been lacking from the VICTORIA model. This report describes the structural heat-up model that has recently been implemented in the code. A sample problem shows that revaporization of fission products can occur as structures heat up due to radioactive decay. In the sample problem, the mass of deposited fission products reaches a maximum, then diminishes. Similarly, temperatures of the deposited film and adjoining structure reach a maximum, then diminish.
This performance assessment characterized plausible treatment options conceived by the Idaho National Engineering Laboratory (INEL) for its spent fuel and high-level radioactive waste and then modeled the performance of the resulting waste forms in two hypothetical, deep, geologic repositories: one in bedded salt and the other in granite. The results of the performance assessment are intended to help guide INEL in its study of how to prepare wastes and spent fuel for eventual permanent disposal. This assessment was part of the Waste Management Technology Development Program designed to help the US Department of Energy develop and demonstrate the capability to dispose of its nuclear waste, as mandated by the Nuclear Waste Policy Act of 1982. The waste forms comprised about 700 metric tons of initial heavy metal (or equivalent units) stored at the INEL: graphite spent fuel, experimental low enriched and highly enriched spent fuel, and high-level waste generated during reprocessing of some spent fuel. Five different waste treatment options were studied; in the analysis, the options and resulting waste forms were analyzed separately and in combination as five waste disposal groups. When the waste forms were studied in combination, the repository was assumed to also contain vitrified high-level waste from three DOE sites for a common basis of comparison and to simulate the impact of the INEL waste forms on a moderate-sized repository, The performance of the waste form was assessed within the context of a whole disposal system, using the U.S. Environmental Protection Agency`s Environmental Radiation Protection Standards for Management and Disposal of Spent Nuclear Fuel, High-Level and Transuranic Radioactive Wastes, 40 CFR 191, promulgated in 1985. Though the waste form behavior depended upon the repository type, all current and proposed waste forms provided acceptable behavior in the salt and granite repositories.
The purpose of this document is to present technical information that should be useful for understanding and applying locking systems for physical protection and control. There are major sections on hardware for locks, vaults, safes, and security containers. Other topics include management of lock systems and safety considerations. This document also contains notes on standards and specifications and a glossary.
To extend the life of gas delivery systems and improve wafer yields, there is a need for an in-line monitor of H{sub 2}O contamination. Goal of this project is to develop such an instrument, based on infrared spectroscopy, that has a detection limit of 30 ppB or better and costs $50K or less. This year`s work considered the application of Fourier transform infrared (FTIR) spectroscopy to H{sub 2}O detection in N{sub 2} and HCl. Using a modified commercial FTIR spectrometer and a long-path gas cell, a detection limit of about 10 ppB was demonstrated for H{sub 2}O in N{sub 2} and HCl. This includes about a factor of three improvement achieved by applying quantitative multivariate calibration methods to the problem. Absolute calibration of the instrument was established from absorptivities of prominent H{sub 2}O bands between 3600 and 3910 cm{sup {minus}1}. Methods are described to minimize background moisture in the beam path. Spectral region, detector type, resolution, cell type, and path length were optimized. Resolving the narrow H{sub 2}O bands (FWHM {approx} 0.20 cm{sup {minus}1}) is not necessary to achieve optimal sensitivity. In fact, optimal sensitivity is achieved at 2 to 4 cm{sup {minus}1} resolution, allowing the use of an inexpensive interferometer. A much smaller, second generation instrument is described that will have a conservatively estimated detection limit of 1 ppB. Since the present laboratory instrument can be duplicated in its essential parts for about $90K, it is realistic to project a cost of $50K for the new instrument. An accessory for existing FTIR spectrometers was designed that may be marketed for as little as $10K.
A dynamic simulator of the TOPAZ II reactor system has been developed for the Nuclear Electric Propulsion Space Test Program. The simulator combines first-principle modeling and empirical correlations in its algorithm to attain the modeling accuracy and computational through-put that are required for real-time execution. The overall execution time of the simulator for each time step is 15 ms when no data is written to the disk, and 18 ms when nine double precision data points are written to the disk once in every time step. The simulation program has been tested and it is able to handle a step decrease of $8 worth of reactivity. It also provides simulations of fuel, emitter, collector, stainless steel, and ZrH moderator failures. Presented in this paper are the models used in the calculations, a sample simulation session, and a discussion of the performance and limitations of the simulator. The simulator has been found to provide realistic real-time dynamic response of the TOPAZ II reactor system under both normal and casualty conditions.
Samples of chemically-vapor-deposited micrometer and sub-micrometer-thick films of polysilicon were analyzed by transmission electron microscopy (TEM) in cross-section and by Raman spectroscopy with illumination at their surface. TEM and Raman spectroscopy both find varying amounts of polycrystalline and amorphous silicon in the wafers. Raman spectra obtained using blue, green and red excitation wavelengths to vary the Raman sampling depth are compared with TEM cross-sections of these films. Films showing crystalline columnar structures in their TEM micrographs have Raman spectra with a band near 497 cm{sup {minus}1} in addition to the dominant polycrystalline silicon band (521 cm{sup {minus}1}). The TEM micrographs of these films have numerous faulted regions and fringes indicative of nanometer-scale silicon structures, which are believed to correspond to the 497cm{sup {minus}1} Raman band.
Optical communication is likely to significantly speed up parallel computation because the vast bandwidth of the optical medium can be divided to produce communication networks of very high degree. However, the problem of contention in high-degree networks makes the routing problem in these networks theoretically (and practically) difficult. In this paper we examine Valiant`s h-relation routing problem, which is a fundamental problem in the theory of parallel computing. The h-relation routing problem arises both in the direct implementation of specific parallel algorithms on distributed-memory machines and in the general simulation of shared memory models such as the PRAM on distributed-memory machines. In an h-relation routing problem each processor has up to h messages that it wishes to send to other processors and each processor is the destination of at most h messages. We present a lower bound for routing an h-relation (for any h > 1) on a complete optical network of size -n. Our lower bound applies to any randomized distributed algorithm for this task. Specifically, we show that the expected number of communication steps required to route an arbitrary h-relation is {Omega}(h + {radical}log log n). This is the first known lower bound for this problem which does not restrict the class of algorithms under consideration.
The combined dynamic environments of vibration and linear acceleration are common to a large number of spacecraft components and other devices. Testing such devices has normally been a two-step process in which independent vibration and centrifuge tests are performed. There is a concern that the combined effects from these two dynamic environments could cause unexpected operational failures that were not predicted from either analysis or independent testing. This paper describes the design and performance of a testing facility that combines vibration and centrifuge testing in a single operation. The test facility is called the Vibrafuge and utilizes Sandia National Laboratories' (SNL) 29-ft underground centrifuge with an attached electrodynamic shaker. Also addressed are activities underway at SNL on development of a combined vibration and acoustic test facility (ATF).
An Integrated Demonstration Program, hosted by the Fernald Environmental Restoration Management Corporation (FERMCO), has been established for investigating technologies applicable to the characterization and remediation of soils contaminated with uranium. An important part of this effort is the evaluation of field screening tools capable of acquiring high resolution information on the distribution of uranium contamination in surface soils in a cost-and-time efficient manner. Consistent with this need, four field screening technologies have been demonstrated at two hazardous waste sites at the FERMCO. The four technologies tested are wide-area gamma spectroscopy, beta scintillation counting, laser ablation-inductively coupled plasma-atomic emission spectroscopy (LA-ICP-AES), and long-range alpha detection (LRAD). One of the important findings of this demonstration was just how difficult it is to compare data collected by means of multiple independent measurement techniques. Difficulties are attributed to differences in measurement scale, differences in the basic physics upon which the various measurement schemes are predicated, and differences in the general performance of detector instrumentation. It follows that optimal deployment of these techniques requires the development of an approach for accounting for the intrinsic differences noted above. As such, emphasis is given in this paper to the development of a methodology for integrating these techniques for use in site characterization programs as well as the development of a framework for interpreting the collected data. The methodology described here also has general application to other field-based screening technologies and soil sampling programs.
This paper describes the development and use of the Multi-Axis Seam Tracking (MAST) sensor for tracking seams or other features in real-time. Four independent, spatially-distributed electric fields are used to sense changes in the relative position of the sensor and the workpiece. The MAST sensor is very inexpensive compared with commercially available seam tracking sensors. It can be used in systems to perform cost-effective small-lot manufacturing operations in a faster, more consistent manner. The MAST sensor is used in an automated system for dispensing braze paste during a rocket nozzle fabrication process.
Pitting of 1100 Al(Al-1.0(Fe,Cu,Si)) due to Al{sub 3}Fe constituent particles has been studied by examining a variety of intrinsic, extrinsic, and environmental factors that contribute to localized corrosion. Consistent with results from other studies, Al{sub 3}Fe is noble with respect to its microstructural surroundings and pitting is localized to the particle periphery. Polarization curves indicate that cathodic electron transfer reactions are supported on Al{sub 3}Fe at high rates, however, a anodic electron transfer reactions are not. Interparticle spacing appears to play a strong role in determining where pitting will occur, while Al{sub 3}Fe particle area plays a lesser role. Solution pH, applied potential, and exposure time each have measurable effects on the electrochemical behavior of Al{sub 3}Fe and the {alpha}-Al matrix phase which can impact either the galvanic potential of the Al{sub 3}Fe/{alpha}-Al couple, or charge transfer processes on Al{sub 3}Fe particles.
Using surface acoustic wave (SAW) devices, three approaches to the effective use of chemically sensitive interfaces that are not highly chemically selective have been examined: (1) molecular identification from time-resolved permeation transients; (2) using multifrequency SAW devices to determine the frequency dependence of analyte/film interactions; (3) use of an array of SAW devices bearing diverse chemically sensitive interfaces to produce a distinct response pattern for each analyte. In addition to their well-known sensitivity to mass changes (0.0035 monolayer of N{sub 2} can be measured), SAW devices respond to the mechanical and electronic properties of thin films, enhancing response information content but making a thorough understanding of the perturbation critical. Simultaneous measurement of changes in frequency and attenuation, which can provide the information necessary to determine the type of perturbation, are used as part of the above discrimination schemes.
We present a global motion planner for tracing curves in three dimensions with robot manipulator tool frames. This planner generates an efficient motion satisfying three types of constraints; constraints on the tool tip for curve tracing, robot kinematic constraints and robot-link collision constraints. Motions are planned using a global search algorithm and a local planner based on a potential-field approach. This planner can be used with potential-field approach. This planner can be used with any robots including redundant manipulators, and can any robots including redundant manipulators, and can control the trade-offs between its algorithmic completeness and computation time. It can be applied in many robotic tasks such as seam welding, caulking, edge deburrring and chamfering, and is expected to reduce motion programming times from days to minutes.
Robotic systems are often very complex and difficult to operate, especially as multiple robots are integrated to accomplish difficult tasks. In addition, training the operators of these complex robotic systems is time-consuming and costly. In this paper, a virtual reality based robotic control system is presented. The virtual reality system provides a means by which operators can operate, and be trained to operate, complex robotic systems in an intuitive, cost-effective way. Operator interaction with the robotic system is at a high, task-oriented, level. Continuous state monitoring prevents illegal robot actions and provides interactive feedback to the operator and real-time training for novice users.
A sensor-based control approach for real-time seam tracking of rocket thrust chamber assemblies has been developed to enable automation of a braze paste dispensing process. This approach utilizes a non-contact Multi-Axis Seam Tracking (MAST) sensor to track the seams. Thee MAST sensor measures capacitance variations between the sensor and the workpiece and produces four varying voltages which are read directly into the robot controller. A PID control algorithm which runs at the application program level has been designed based upon a simple dynamic model of the combined robot and sensor plant. The control algorithm acts on the incoming sensor signals in real-time to guide the robot motion along the seam path. Experiments demonstrate that seams can be tracked at 100 mm/sec within the accuracy required for braze paste dispensing.
Probabilistic risk assessment (PRA) is a process for evaluating hazardous operations by considering what can go wrong, the likelihood of these undesired events, and the resultant consequences. Techniques used in PRA originated in the 1960s. Although there were early exploratory applications to nuclear weapons and other technologies, the first major application of these techniques was in the Reactor Safety Study, WASH-1400, {sup 1} in which the risks of nuclear power accidents were thoroughly investigated for the first time. Recently, these techniques have begun to be adapted to nuclear weapon system applications. This report discusses this application to nuclear weapon systems.
In this paper, we present a new hybrid motion planner than is capable of exploiting previous planning episodes when confronted with new planning problems. Our approach is applicable when several (similar) problems are successively posed for the same static environment, or when the environment changes incrementally between planning episodes. At the heart of our system lie two low-level motion planners: a fast, but incomplete planner (which we call LOCAL), and a computationally costly (possibly resolution) complete planner (which we call GLOBAL). When a new planning problem is presented to our planner, a meta-level planner (which we call MANAGER) decomposes the problem into segments that are amenable to solution by LOCAL. This decomposition is made by exploiting a task graph, in which successful planning episodes have been recorded. In cases where the decomposition fails, GLOBAL is invoked. The key to our planner`s success is a novel representation of solution trajectories, in which segments of collision-free paths are associated with the boundary of nearby obstacles.
Sandia has been studying automatic assembly planning of electromechanical devices for some years, based on an implemented system called Archimedes. Work done to date has focussed on automatic generation of high-level plans, and translation of these plans into robotic control code and workcell layout. More recently, the importance of an assembly planning capability as a design aid has been emphasized, as it could potentially provide early feedback to a designer on the manufacturability of the design. This paper describes the work done on assembly planning to date, plans for extending it, and its applications to agile manufacturing. In particular, we describe an agile manufacturing demonstration project underway at Sandia, and the role the Archimedes assembly planning system will play in it.
Today, 109 nuclear power plants provide over 20 percent of the electrical energy generated in the US The operating license of the first of these plants will expire in the year 2000; one-third of the operating licenses will expire by 2010 and the remaining plant licenses are scheduled to expire by 2033. The National Energy Strategy assumes that 70 percent of these plants will continue to operate beyond their current license expiration to assist in ensuring an adequate, diverse, and environmentally acceptable energy supply for economic growth. In order to preserve this energy resource in the US three major tasks must be successfully completed: establishment of regulations, technical standards, and procedures for the preparation and review of a license renewal application; development, verification, and validation of technical criteria and bases for monitoring, refurbishing, and/or replacing plant equipment; and demonstration of the regulatory process. Since 1985, the US Department of Energy (DOE) has been working with the nuclear industry and the US Nuclear Regulatory Commission (NRC) to establish and demonstrate the option to extend the life of nuclear power plants through the renewal of operating licenses. This paper focuses primarily on DOE`s Plant Lifetime Improvement (PLIM) Program efforts to develop the technical criteria and bases for effective aging management and lifetime improvement for continued operation of nuclear power plants. This paper describes current projects to resolve generic technical issues in the principal areas of reactor pressure vessel (RPV) integrity, fatigue, and environmental qualification (EQ).
We have evaluated a wide variety of microcellular carbon foams prepared by the controlled pyrolysis and carbonization of several polymers including: polyacrylonitrile (PAN), polymethacrylonitrile (PMAN), resorcinol/formaldehyde (RF), divinylbenzene/methacrylonitrile (DVB), phenolics (furfuryl/alcohol), and cellulose polymers such as Rayon. The porosity may be established by several processes including: Gelation (1-5), phase separation (1-3,5-8), emulsion (1,9,10), aerogel/xerogel formation (1,11,12,13), replication (14) and activation. In this report we present the complex impedance analysis and double layer charging characteristics of electrodes prepared from one of these materials for double layer capacitor applications, namely activated cellulose derived microcellular carbon foam.
This paper evaluates the correlation between values of minimum principal in situ stress derived from two different models which use data obtained from triaxial core tests and coefficient for earth at rest correlations. Both models use triaxial laboratory tests with different confining pressures. The first method uses a vcrified fit to the Mohr failure envelope as a function of average rock grain size, which was obtained from detailed microscopic analyses. The second method uses the Mohr-Coulomb failure criterion. Both approaches give an angle in internal friction which is used to calculate the coefficient for earth at rest which gives the minimum principal in situ stress. The minimum principal in situ stress is then compared to actual field mini-frac test data which accurately determine the minimum principal in situ stress and are used to verify the accuracy of the correlations. The cores and the mini-frac stress test were obtained from two wells, the Gas Research Institute`s (GRIs) Staged Field Experiment (SFE) no. 1 well through the Travis Peak Formation in the East Texas Basin, and the Department of Energy`s (DOE`s) Multiwell Experiment (MWX) wells located west-southwest of the town of Rifle, Colorado, near the Rulison gas field. Results from this study indicates that the calculated minimum principal in situ stress values obtained by utilizing the rock failure envelope as a function of average rock grain size correlation are in better agreement with the measured stress values (from mini-frac tests) than those obtained utilizing Mohr-Coulomb failure criterion.
Currently, the production of in situ reinforcement in polymeric systems by sol-gel methods is undergoing rapid development. However, understanding of synthesis/structure/property relationships is still lacking. In order to produce sol-gel derived composite materials with sufficient mechanical properties for commercial applications, this deficit of information must be addressed. We have completed a detailed investigation of in situ silica growth in polydimethylsiloxane (PDMS)/tetraethylorthosilicate (TEOS) systems. Factors which affect the domain growth, such as catalyst activity and silica loading, have been examined by solid state {sup 29}Si NMR, SEM, mechanical testing and small angle neutron scattering.
Infrared emission spectra of 21 borophosphosilicate glass (BPSG) thin films on silicon wafers were collected with the samples held at constant temperature between 125--400{degree}C using a heating stage designed for precise temperature control ({plus_minus}{degree}C). Partial test squares calibrations applied to the BPSG infrared emittance spectra allowed four BPSG thin-film properties to be simultaneously quantified with precisions of 0.1 wt. % for boron and phosphorus, 35 {Angstrom} for film thickness, and 1.2{degree}C for temperature.
Experiments were performed to examine sensitivity of thin-film property determinations to several experimental variables when applying multivariate calibration methods to infrared reflection spectroscopic data. Results indicate that low angles of incidence are best for robust quantitative determination of boron, phosphorus, and film thickness in borophosphosilicate glass (BPSG) dielectric films. However, the polarization state of the incidence beam does not affect the quantitative prediction ability.
Due to the growth in the use of analog fiber optic data transmission systems at the Nevada Test Site and other locations, Sandia National Laboratories (SNL) has recognized the need to be able to multiplex several data channels per fiber. Wavelength-division, frequency-division, and time-division multiplex techniques have been investigated. A time-division system using optically-multiplexed laser transmitters driving a common receiver was fielded on the HUNTERS TROPHY event at the NTS. Stability, noise, and dynamic range compared favorably with that seen on nonmultiplexed links. Amplitude, width, and rise time of data transmitted via the multiplexed links was consistent with that recorded from non-multiplexed links.
