In keeping with the philosophy of the external events analyses for NUREG-1150, which are intended to be smart probabilistic risk assessments (PRAs) making full use of all insights gained during the past 10 years of development in risk assessment methodologies, the Savannah River K-Reactor fire analysis was performed using newly developed and simplified methods. These methods have been under development at Sandia National Laboratories under sponsorship of the Nuclear Regulatory Commission (NRC) Division of Risk Assessment as part of the Dependent Failure Methodology Development Program. A detailed screening analysis was performed which showed most plant areas had a negligible contribution to fire-induced core damage frequency. Detailed analysis of the fire risk resulted in a total (mean) core damage frequency of 1.35E-7 per year. 18 refs., 12 figs., 17 tabs.
The project comprises the development of concentrating solar collectors, heliostats and dishes, and the development of optical materials. Because the solar concentrator represents from 40 to 60% of the cost of a solar thermal electric system, the continued development of high-performance concentrators is very important to the commercial viability of these systems. The project is currently testing two large area heliostats, the SPECO 200 m{sup 2} heliostat and the ATS 150 m{sup 2} heliostat and also trying to reduce the cost of the heliostats through the development of stretched-membrane heliostats. Stretched-membrane heliostats are made by attaching thin metal membranes to the two sides of a circular, metal ring. A slight vacuum in the plenum between the two membranes is used to focus the heliostat. The optical surface is provided by a silver-acrylic film, ECP 305. A prototype 100 m{sup 2} commercial unit has been built and is currently being tested. Parabolic dish concentrators are under development for use on dish-Stirling electric systems. The state-of-the-art dish is the McDAC/SCE faceted glass concentrator. Because of the success of stretched-membrane technology for heliostats, the project applied the technology to parabolic dish development and is currently designing a near-term, faceted, stretched-membrane dish. The current thrust of the program in optical materials development is the development of a low-cost, high-performance, silver-acrylic film. 3M's ECP 305 has demonstrated substantial improvement over previous films in its resistance to corrosion, longer life. An experimental film, developed at SERI, has promise for further improving the lifetime of the ECP 305. The project is currently investigating solutions to the problem of separation between the silver and acrylic layers of the film in the presence of water.
Double-Layer Capacitors (DLCs) have been used mainly for computer memory backup in consumer applications during the last ten years. Their high capacitance density, along with maintenance-free operation, makes them suited for these applications. In recent years users, mostly in military applications, have expressed interest in using DLCs in high reliability applications both for backup power and pulse power applications. To meet this need, developers have pursued technologies that use carbon and mixed metal oxides as the electrode material to produce high reliability double-layer capacitors. In this paper, a carbon-based DLC that was manufactured by Evans Company, and a mixed metal oxide (MMO) DLC by Pinnacle Research Inc. were evaluated. There is little published data on their reliability and aging characteristics. In addition, questions have arisen as to their environmental stability as a function of temperature, shock, vibration, and linear acceleration. The purpose of this paper is to review the available test data for both types of DLCs under these stress conditions. The data for this paper was generated by Sandia National Laboratories, General Electric Neutron Devices Department, Motorola Company, and Evans Company.
A technique to localize errors between two modal models is presented. Mode shape difference are calculated from each model. A global comparison of the ratios of these corresponding differences is used to identify the physical locations on the structure where stiffness differences exist between the two models. Some of the strengths and limitations of the technique are illustrated using the mode shapes of two similar finite element models with a known stiffness difference. The technique is then applied to a two link robot arm for which a finite element model exists and a modal test has been conducted. The results of the error localization aid the selection of physical parameters to be updated in the finite element model. Sensitivity methods are used to correlate the finite element model to the modal test. The results of the correlation are presented. 5 refs., 3 figs., 3 tabs.
This paper will provide an overview of cleaning qualifications used in a variety of industries: from small-scale manufacturer's of precision-machined products to large-scale manufacturer's of electronics (printed wiring boards and surface mount technology) and microelectronics. Cleanliness testing techniques used in the production of precision-machined products, will be described. The on-going DOD program to obtain high-reliability electronics, through the use of military specifications for cleaning and cleanliness levels, will be reviewed. In addition, the continually changing cleanroom/materials standards of the microelectronics industry will be discussed. Finally, we will speculate on the role that new and improved analytical techniques and sensor technologies will play in the factories of the future. 4 refs., 1 tab.
Ray paths and focal lengths are derived to fourth order for a nuclear-reactor wall-pumped gas laser. Ray paths in the laser gain cell are shown to be nearly random for a long gain region. Focal lengths calculated from the ray paths exiting the laser are shown to oscillate between {plus minus} {infinity} during pumping. The use of stimulated Brillouin scattering as a means for beam clean-up is discussed with the conclusion that the phase conjugated beam would cycle on and off as the ray paths and focal lengths oscillate between extremes. The parameters determining this cycling effect and its characteristics are also derived. 17 refs., 11 figs., 1 tab.
MELCOR is a fully integrated, engineering-level computer code that models the progression of severe accidents in light water reactor nuclear power plants. MELCOR is being developed at Sandia National Laboratories for the US Nuclear Regulatory Commission as a second-generation plant risk assessment tool and the successor to the Source Term Code Package. The entire spectrum of severe accident phenomena, including reactor coolant system and containment thermal-hydraulic response, core heatup, degradation and relocation, and fission product release and transport, is treated in MELCOR in a unified framework for both boiling water reactors and pressurized water reactors. MELCOR has been especially designed to facilitate sensitivity and uncertainty analyses. Its current uses include estimation of severe accident source terms and their sensitivities and uncertainties in a variety of applications. This report is a summary of MELCOR 1.8.0, the code version released in March 1989. Condensed information is presented on its developmental history, structure, modeling features and capabilities, verification and validation, and quality assurance. Detailed documentation on these aspects of MELCOR, including users' guides, reference manuals, programmers' guides, and assessment and application reports, is available in draft form and is distributed to MELCOR users.
Experimental tests on the Annular Core Research Reactor have confirmed that the Three-Bean-Salad'' control algorithm based on the Pontryagin maximum principle can change the power of a nuclear reactor many decades with a very fast startup rate and minimal overshoot. The paper describes the results of simulations and operations up to 25 MW and 87 decades per minute. 3 refs., 4 figs., 1 tab.
The spherical element computer code DMC (Distinct Motion Code) used to model rock motion resulting from blasting has been enhanced to allow routine computer simulations of bench blasting. The enhancements required for bench blast simulation include: (1) modifying the gas flow portion of DMC, (2) adding a new explosive gas equation of state capability, (3) modifying the porosity calculation, and (4) accounting for blastwell spacing parallel to the face. A parametric study performed with DMC shows logical variation of the face velocity as burden, spacing, blastwell diameter and explosive type are varied. These additions represent a significant advance in the capability of DMC which will not only aid in understanding the physics involved in blasting but will also become a blast design tool. 8 refs., 7 figs., 1 tab.
Nd:YAG laser cleaning of metal oxides from 304L stainless steel surfaces has been characterized. Thin chromium oxide films can be completely removed from the surface using a single 10 nsec pulse of laser radiation with an average surface irradiance greater than 120 MW/cm{sup 2}. Laser etching of thicker iron oxide films exhibit a self-limiting effect that prevents overetching into the stainless steel substrate. 8 figs.
Electron-Beam (EBeam) melting furnaces are routine used to minimize the occurrence of second-phase particles in the processing of segregation-sensitive alloys. As one part of the process, a circulating electron beam impinges the surface of a crucible melt pool to help control the shape of the solidification front below. By modeling melt pool hydrodynamics, heat transfer, and the shape of solidification boundaries, we plan to optimize the dwell pattern of the beam so that the material solidifies with a composition as spatially homogeneous as possible. Both two- and three-dimensional models are being pursued with FIDAP 5.02, the former serving as a test bed for various degrees of model sophistication. A heat flux distribution is specified on the top of the domain to simulate the EBeam dwell pattern. In two dimensions it is found that an inertially-driven recirculation in the melt pool interacts with a counter-rotating buoyancy-driven recirculation, and that both recirculations are influenced heavily by surface tension gradients on the melt-pool surface. In three dimensions the inertial cell decays quickly with distance from the position of the inlet stream, causing the fluid to precess the crucible. Ingot macrosegregation patterns for a U-6 wt. % Nb alloy are calculated with the Flemings-Mehrabian equation of solute redistribution; the sensitivity of these patterns to EBeam dwell pattern is explored.
The LIFE2 computer code is a fatique/fracture analysis code that is specialized to the analysis of wind turbine components. The numerical formulation of the code uses a series of cycle count matrices to describe the cyclic stress states imposed upon the turbine. In this formulation, each stress cycle is counted or binsed'' according to the magnitude of its mean stress and alternating stress components and by the operating condition of the turbine. A set of numerical algorithms has been incorporated into the LIFE2 code. These algorithms determine the cycle count matrices for a turbine component using stress-time histories of the imposed stress states. This paper describes the design decisions that were made and explains the implementation of these algorithms using Fortran 77. 7 refs., 7 figs.
The CONTAIN quality assurance program follows a strict set of procedures designed to ensure the integrity of the code, to avoid errors in the code, and to prolong the life of the code. The code itself is maintained under a code-configuration control system that provides a historical record of changes. All changes are incorporated using an update processor that allows separate identification of improvements made to each successive code version. Code modifications and improvements are formally reviewed and checked. An exhaustive, multilevel test program validates the theory and implementation of all codes changes through assessment calculations that compare the code-predicted results to standard handbooks of idealized test cases. A document trail and archive establish the problems solved by the software, the verification and validation of the software, software changes and subsequent reverification and revalidation, and the tracking of software problems and actions taken to resolve those problems. This document describes in detail the CONTAIN quality assurance procedures.
The 10-MW{sub e} Solar One Pilot Plant was the world's largest solar central receiver power plant. During its power production years it delivered over 37,000 MWhrs (net) to the utility grid. In this type of electric power generating plant, large sun-tracking mirrors called heliostats reflect and concentrate sunlight onto a receiver mounted on top a of a tower. The receiver transforms the solar energy into thermal energy that heats water, turning it into superheated steam that drives a turbine to generate electricity. The Solar One Pilot Plant successfully demonstrated the feasibility of generating electricity with a solar central receiver power plant. During the initial 2 years the plant was tested and 4 years the plant was operated as a power plant, a great deal of data was collected relating to the efficiency and reliability of the plant's various systems. This paper summarizes these statistics and compares them to goals developed by the US Department of Energy. Based on this comparison, improvements in the design and operation of future central receiver plants are recommended. Research at Sandia National Laboratories and the US utility industry suggests that the next generation of central receiver power plants will use a molten salt heat transfer fluid rather than water/steam. Sandia has recently completed the development of the hardware needed in a molten salt power plant. Use of this new technology is expected to solve many of the performance problems encountered at Solar One. Projections for the energy costs from these future central receiver plants are also presented. For reference, these projections are compared to the current energy costs from the SEGS parabolic trough plants now operating in Southern California.
The results of the first year of an evaluation of charge controllers for stand-alone photovoltaic (PV) systems are presented. The objectives of the test program are to positively influence the development of battery charge controllers for stand-alone PV applications and to develop design and application criteria that will improve PV system reliability and battery performance. Future goals are to expand the evaluation program to include various battery technologies and controller algorithms. Also, the information is being communicated to manufacturers to aid in the design of more effective and reliable charge controllers for PV systems. Eight different models of small (nominal 10 amp) charge controllers are being subjected to a comprehensive evaluation. These evaluations include operational tests in identical stand-alone PV systems and environmental and electrical cycling tests. Selected custom tests are also performed on the controllers to determine the response to transients, installation requirements and system design compatibilities. Data presented in this paper include measured electrical characteristics of the controllers, temperature effects on set points, and operational performance in PV systems both in the lab and in the field. A comparison is presented for four different charge controller algorithms which include array-shunt, series-interrupting, series-linear constant-voltage and series-linear-multistep constant-current. 9 refs., 11 figs., 2 tabs.
SAS software is being used to analyze product test data stored in an INGRES relational database. The database has been implemented at Allied-Signal in Kansas City on a Digital Equipment Corporation (DEC) VAX computer. The INGRES application development has been a joint project between Sandia National Laboratories and Allied-Signal. Application screens have been developed so that the user can query the database for selected data. Fourth generation language procedures are used to retrieve all data requested. FORTRAN and VAX/VMS DCL (DIGITAL Control Language) procedures are invoked from the application to create SAS data sets and dynamically build SAS programs that are executed to build custom reports or graphically display the retrieved test data along with control and specification limits. A retrieval screen has also been developed which invokes SAS software to calculate the mean and standard deviation of the retrieved data. These parameters are passed back into the application for display and may then be used as an aid in setting new control limits for future test runs. Screens have been developed to provide an interface for the user to select from a library of SAS programs, edit the selected program, and run the program with a user-defined SAS data set as input. This paper will give a brief description of the application screens and provide details of how information is passed between the application and SAS programs.
I was asked to write a database application that would be user friendly to the extent that a minimum amount of learning would be required of the user to run the application, yet it would be flexible enough to gather the data in various combinations. Writing SELECT'' or RETRIEVE'' queries required to much initial training. Hard coding queries into the application meant the users could not pick columns or create contraints. I decided to compromise somewhat, requiring my users to learn how to manipulate VIFRED menus and by doing so they could pick any combination of columns for output, select any column variable to sort on, and impose simple, yet practical constaints on the data, all this possible at run time. This handout contains copies of the VIFRED menus, the help message for imposing constraints, output from sample retrievals, descriptions of the relational tables needed to implement the methodology, and the computer coding of the actual retrieval construction.
Burnup credit is the application of the effects of fuel burnup to nuclear criticality design. When burnup credit is considered in the design of storage facilities and transportation casks for spent fuel, the objectives are to reduce the requirements for storage space and to increase the payload of casks with acceptable nuclear criticality safety margins. The spent-fuel carrying capacities of previous-generation transport casks have been limited primarily by requirements to remove heat and/or to provide shielding. Shielding and heat transfer requirements for casks designed to transport older spent fuel with longer decay times are reduced significantly. Thus a considerable weight margin is available to the designer for increasing the payload capacity. One method to achieve an increase in capacity is to reduce fuel assembly spacing. The amount of reduction in assembly spacing is limited by criticality and fuel support structural concerns. The optimum fuel assembly spacing provides the maximum cask loading within a basket that has adequate criticality control and sufficient structural integrity for regulatory accident scenarios. The incorporation of burnup credit in cask designs could result in considerable benefits in the transport of spent fuel. The acceptance of burnup credit for the design of transport casks depends on the resolution of system safety issues and the uncertainties that affect the determination of criticality safety margins. The remainder of this report will examine these issues and the integrated approach under way to resolve them. 20 refs., 2 figs.
Dip coating is the primary means of depositing sol-gel films for precision optical coatings. Sols are typically multicomponent systems consisting of an inorganic phase dispersed in a solvent mixture, with each component differing in volatility and surface tension. This, together with slow coating speeds (<1cm/s), makes analysis of the coating process complicated; unlike most high-speed coating methods, solvent evaporation, evolving rheology, and surface tension gradients alter significantly the fluid mechanics of the deposition stage. We set out to understand these phenomena with computer-aided predictions of the flow and species transport fields. The underlying theory involves mass, momentum, and species transport on a domain of unknown shape, with models and constitutive equations for vapor-liquid equilibria and surface tension. Due accounting is made for the unknown position of the free surface, which locates according to the capillary hydrodynamic forces and solvent loss by evaporation. Predictions of the effects of mass transfer, hydrodynamics, and surface tension gradients on final film thickness are compared with ellipsometry measurements of film thickness on a laboratory pilot coater. Although quantitative agreement is still lacking, both experiment and theory reveal that the film profile near the drying line takes on a parabolic shape. 2 refs., 2 figs.
Sandia National Laboratories is a multiprogram engineering laboratory that serves the nation through the Department of Energy (DOE), both in its programs and those of other agencies. Major research and development responsibilities cover nuclear weapons, arms control, energy, environment and other areas of strategic importance to national security. The principal mission is to support national defense policies by ensuring that the nuclear weapon stockpile meets the highest standards of safety, security, control and military performance. In May of 1968, the Albuquerque Office of DOE (then AEC) assigned the Quality Assurance function to Sandia Laboratories on all products for which Sandia has design responsibility. The Sandia Quality Improvement Plan presents a Quality Management System that integrates the Sandia quality policies and several independent improvement processes into a cohesive structure. This structure guides day-to-day operations toward strategic objectives. The Sandia Quality Policy provides the underlying principles for the management of our research and engineering efforts and establishes our customers as the central focus of our Sandia quality improvement efforts. Operationally, these efforts are centered around quality improvement processes based on good management practices developed by AT T, and progress is measured against the Malcolm Baldridge National Quality Award criteria. Developing a comprehensive plan based on these processes requires that we determine where we are, where we want to be, and how we measure our progress. 1 fig. (JF)
A review of the objectives and accomplishments of the Computational Benchmark Problem Committee (CBPC) of the American Nuclear Society Mathematics and Computation Division is presented. A list of the benchmark problems compiled by the CBPC and published by the Argonne Code Center is included, along with a list of the problems currently under review. A brief discussion of the challenge of benchmarking in the current environment of rapidly evolving computing technology is given. 20 refs., 3 tabs.
The Distant Light Program sponsored by the Defense Nuclear Agency (RAEE) is directed toward understanding the response of electronic systems to Source Region EMP (SREMP) and will result in the development of proven system hardening and validation techniques for SREMP. This program relies very strongly on testing in above ground test (AGT) simulators such as the HERMES III gamma ray simulator at Sandia National Laboratories in Albuquerque, New Mexico. This paper describes theoretical and experimental efforts aimed at understanding the gamma ray flux produced by HERMES III in terms of its time dependence, spatial variation and spectrum. As part of this characterization, the calibration of various measuring devices must be considered. This paper describes the progress made in characterizing the HERMES III radiation output through December of 1990.
Lithium batteries have been used in a variety of applications for a number of years. As their use continues to grow, particularly in the consumer market, a greater emphasis needs to be placed on safety and reliability. There is a useful technique which can help to design cells and batteries having a greater degree of safety and higher reliability. This technique, known as fault tree analysis, can also be useful in determining the cause of unsafe behavior and poor reliability in existing designs.
During 1990, Sandia National Laboratories initiated an advanced lead-acid battery development program supported by the US Department of Energy's Office of Energy Management. The goal is to develop a low maintenance, cost effective battery by the mid- to late 1990's that is tailored to a variety of electric utility applications. Several parallel activities are being pursued to achieve this goal. One activity seeks to quantify the economic benefits of battery storage for specific cases in candidate utility systems and identify opportunities for field demonstration of battery systems at electric utility and utility customer sites. Such demonstrations will not only generate valuable operating experience data, but will also help in building user confidence in battery storage systems. Other activities concentrate on cell- and battery-level research and development aimed at overcoming shortcomings in existing technologies, such as Valve-Regulated Lead-Acid (VRLA), or, sealed lead-acid batteries.
This study was undertaken in order to document and analyze the unique set of data on subsurface fracture characteristics, especially spacing, provided by the US Department of Energy's Slant Hole Completion Test well (SHCT-1) in the Piceance Basin, Colorado. Two hundred thirty-six (236) ft (71.9 m) of slant core and 115 ft (35.1 m) of horizontal core show irregular, but remarkably close, spacings for 72 natural fractures cored in sandstone reservoirs of the Mesaverde Group. Over 4200 ft (1280 m) of vertical core (containing 275 fractures) from the vertical Multiwell Experiment wells at the same location provide valuable information on fracture orientation, termination, and height, but only data from the SHCT-1 core allow calculations of relative fracture spacing. Within the 162-ft (49-m) thick zone of overlapping core from the vertical and deviated wellbores, only one fracture is present in vertical core whereas 52 fractures occur in the equivalent SHCT-1 core. The irregular distribution of regional-type fractures in these heterogeneous reservoirs suggests that measurements of average fracture spacing'' are of questionable value as direct input parameters into reservoir engineering models. Rather, deviated core provides data on the relative degree of fracturing, and confirms that cross fractures can be rare in the subsurface. 13 refs., 11 figs.
