We have studied triggering of fuel-coolant interactions, the work performed against the surrounding coolant during the interaction, and the generation of hydrogen produced by melt water chemical reactions with laboratory-scale experiments. We used single drops of three core-melt simulants: (a) molten stoichiometric thermite-generated iron-aluminum oxide melts to simulate the core-melt material that might be produced in the severe accident of an oxide fueled reactor; (b) molten aluminum to simulate melt that might be produced in the severe accident of a nonpower reactor; and (c) an intermediate material, aluminum-enriched iron aluminum oxide thermite, that might simulate severe meltdown of an oxide-metal dispersion fuel (cermet). As a result of these experiments, we have concluded that the peak pressure (or impulse) of the transient is not a governing parameter for the triggering of steam explosions of single drops of melt. We have observed maximum pressure-volume work outputs produced by the aluminum-rich and stoichiometric thermite melts of about 70 and 25 J/g of melt; the corresponding values for molten aluminum at 1273 and 1473 K are about 14 and 21 J/g of melt. The extent of metal-water reaction for the stoichiometric and aluminized melts were 13 and 19%. The aluminum melts at 1273 and 1473 K produced approximately 1 and 3% metal-water reaction.
The hypervelocity impact of a particle on a surface generates a jet of shocked material which is thrown from the impact site. A simple analytic model has been developed to obtain expressions for the evolution of this jet of ejecta. The analysis is based on applying the conservation equations of mass and momentum to the problem of a normal impact of a sphere against a semi-infinite flat target. Expressions are developed for the evolution of the jet velocity, jet release point and the locus of points which describe the ejecta envelope. These analytical ejecta profiles are compared with high speed photographs of impact jet formation.
Many robot control algorithms for high performance in-contact operations including hybrid force/position, stiffness control and impedance control approaches require the command the joint torques. However, most commercially available robots do not provide joint torque command capabilities. The joint command at the user level is typically position or velocity and at the control developer level is voltage, current, or pulse-width, and the torque generated is a nonlinear function of the command and joint position. To enable the application of high performance in-contact control algorithms to commercially available robots, and thereby facilitate technology transfer from the robot control research community to commercial applications, an methodology has been developed to linearize the torque characteristics of electric motor-amplifier combinations. A four degree of freedom Adept 2 robot, having pulse-width modulation amplifiers and both variable reluctance and brushless DC motors, is converted to operate from joint torque commands to demonstrate the methodology. The commercial robot controller is replaced by a VME-based system incorporating special purpose hardware and firmware programmed from experimental data. The performance improvement is experimentally measured and graphically displayed using three-dimensional plots of torque vs command vs position. The average percentage torque deviation over the command and position ranges is reduced from as much as 76% to below 5% for the direct-drive joints 1, 2 and 4 and is cut by one half in the remaining ball-screw driven joint 3. Further, the torque deviation of the direct-drive joints drops below 2.5% if only the upper 90% of the torque range is considered. 23 refs., 20 figs., 2 tabs.
The mechanical behavior of crushed natural rock salt is of concern to the Waste Isolation Pilot Plant (WIPP) Project because excavated salt is a candidate material for use as backfill around the waste packages and in storage rooms, shafts and other underground openings. To complement existing studies on the compaction behavior of dry and damp (i.e., unsaturated) crushed rock salt under hydrostatic compression, we initiated an extensive experimental program to evaluate (1) the effect of brine-saturation on the consolidation rates and terminal densities of crushed salt subjected to hydrostatic compression, and (2) the influence of small deviatoric stresses on the consolidation rate damp crushed rock salt. This investigation is incomplete, and laboratory facilities are limited, therefore, in this report we review available results, in order to make available preliminary estimates of the effects of brine-saturation and shear stress on consolidation. Experiments with brine were carried out under nominally drained conditions. Experiments completed to data include five hydrostatic compaction tests on brine-saturated samples, run at pressures ranging from 1.72 to 10.34 MPa, and two prototype shear consolidation experiments run at a mean stress of 3.45 MPa and a stress difference of 0.69 MPa. Both sets of experiments were run at 20{plus minus}0.5 {degrees}C. Although the experiments on brine-saturated crushed rock salt exhibit several discrepancies, we can draw the following conclusions. (1) Though effects associated with brine-saturated apparently have a retarding effect on consolidation, rates are reduced by less than an order of magnitude when compared with unsaturated specimens. Despite saturation, high fractional densities (>0.95) are attainable even on laboratory time scales using pressures well below lithostatic at the WIPP ({approx} 15 MPa). 23 refs., 26 figs., 5 tabs.
The MERLIN 2 program is designed to transfer data between finite element meshes of arbitrary geometry. The program is structured to accurately interpolate previously computed solutions onto a given mesh and format the resulting data for immediate use in another analysis program. Data from either two-dimensional or three-dimensional meshes may be considered. The theoretical basis and computational algorithms used in the program are described and complete user instructions are presented. Several example problems are included to demonstrate program usage. 13 refs. 15 figs.
This report describes the phenomenological equations and the numerical procedures used by the CONTAIN 1.1 code to determine the conditions within nuclear power plant containment during a severe accident. The CONTAIN detailed models provide the capability to mechanistically calculate the containment internal thermalhydraulic conditions and the amount of radioactive matter that would be released to the environment if there were a leak from the containment. Note that the CONTAIN models can be verified by comparing the code calculations to experimental results. The models described include those to account for the flows of mass and energy between containment compartments, the exchange of energy between the atmosphere and heat structures, the thermodynamic conditions, the distributions of aerosols, the decay and transport of fission products, the deflagration of hydrogen and carbon monoxide, boiling water reactor suppression pool behavior, and engineering safety features, including a spray, fan coolers, and an ice condenser. These models are solved with implicit coupling, where appropriate, to obtain a stable and computationally efficient solution. 52 refs., 36 figs., 9 tabs.
The Primary Standards Laboratory (PSL) operates a system-wide primary standards and calibration program for the US Department of Energy, Albuquerque Operations Office (DOE/AL). The PSL mission is as follows: to develop and maintain primary standards; to calibrate electrical, physical, and radiation reference standards for customer laboratories (DOE/Al integrated contractors); to conduct technical surveys and audits of these laboratories; and to recommend and implement system-wide improvements. This report summarizes activities of the PSL for the second half of 1990 and provides information pertinent to the operation of the DOE/AL Standards and Calibration Program. Specific areas covered include development projects, improvement projects, calibration and special measurements, surveys and audits, and significant events. Activities in these areas have been at a lower than normal level because of response to increased Environment, Safety, and Health (ES H) concerns and preparation for a Tiger Team visit. Appendices include certifications and reports, commercial calibration laboratories, PSL memoranda, and National Institute of Standards and Technology ((NIST)--formerly the National Bureau of Standards (NBS)) test numbers.
Sandia National Laboratories has developed an advanced self-contained tracking control system for use with one- or two-axis tracking solar arrays. The SolarTrak system computes the sun's position based on the time and stored position data, and then controls two motors to point the tracker at the sun without using sun sensors. When used with a photovoltaic concentrator array, the system initially performs a self-alignment routine using array-generated current to locate the sun. The routine computes six numbers that are used during the normal operation to correct the array pointing for the tracker's installation misalignment. This enables the tracker to point accurately even with installation misalignments of up to several degrees. The SolarTrak system consists of a control board, which contains a Motorola 68HC11 microcontroller, a power supply board, motor-interface boards, and a hand-held user interface board, which contains a liquid-crystal display and an input keypad. This report contains a thorough discussion of the controller software and hardware, including control algorithms, parts lists and estimated costs (about $300 per system). The performance measured on two trackers is reviewed. Tracking accuracy was better than {plus minus}0.1{degrees} over a full day on one system. A thorough user's manual is included. Companies interested in licensing the technology should contact the Technology Transfer Division of Sandia National Laboratories. 20 refs., 53 figs., 5 tabs.
Simulated DHLW (Defense High Level Waste) package performance tests were carried out at the WIPP (Waste Isolation Pilot Plant) by emplacing a number of waste canisters containing electrical heaters into the floor of the mine. Peak temperatures were about 130{degrees}C, and the tests ran for three years. During this time, an unanticipated large amount of water was collected from heater hole BO42. A study was, therefore, undertaken to determine if this fluid was derived from normal weep brines. This was accomplished by comparing the amount of salt deposited by the dried weep brines with the volume of condensed steam collected during the test. Documenting the post-test condition of the various backfills was the other objective of this report. In spite of being exposed to acidic vapors, the bentonite-sand backfill retained its mineralogic integrity. However, the bentonite-sand backfill compacted between the canister and the wall only achieved a density that was about three quarters that of a pore-free material. The bentonite backfill also showed evidence of hair-line cracks through which steam had left the vicinity of the canister. In contrast, compacted crushed salt backfill exhibited no evidence of through-going cracks and was compacted to better than 99% of that of pure nonporous sodium chloride. Thus, the seal provided by a crushed salt backfill appears to be superior to that provided by bentonite. 13 refs., 6 tabs.
This report provides system designers with basic human factors information and guidelines for designing and developing the software user interface. A brief discussion of the user interface design philosophy is presented, followed by an overview of the user interface options available (such as color and highlighting), candidate approaches, and discussion of general display concepts and user interface features. We have presented information to facilitate discussions of user interface options, to aid in making final user interface design decisions, and to further the refinement of the user interface. We provide a candidate questionnaire for evaluating your software user interface. 41 refs., 3 tabs.
We have conducted an extensive investigation of the split cavity oscillator (SCO) using particle-in-cell simulation. The goal of this work is to test and optimize an inverse diode rf convertor for use with a cylindrical SCO, while simultaneously determining factors that control rf extraction efficiency. We present results from simulations of several configurations including the SCO with inverse diode extractor, the SCO in conjunction with post-acceleration and inverse diode extraction, and the SCO, using electron beams with a variety of currents, voltages, and radii. 7 refs., 8 figs.
This report presents an assessment of ambient temperature rechargeable lithium batteries for electric vehicle applications. It was prepared for the Department of Energy, Office of Propulsion Systems. The status of development programs in industry and research laboratories was determined for several positive and negative electrode materials and for organic liquid and solid polymer electrolytes. Recommendations are suggested for future research and development activities. 217 refs.
The hydrodynamic blast created by the initiation of a 1 kev X-ray source from an arc-induced ionized gas column, involves density and temperature ratios of such magnitude that the strong shock theory of propagation from continuum fluid mechanics does not apply. Because these simulations occurs in a near vacuum, the continuum equations of motion break down and become invalid during the expansion process as the wavefront density decreases. This report summarizes an approximate treatment of the hydrodynamics of a strong explosion followed by an expanding wavefront in a near vacuum. The analysis was performed in support of the Saturn program to assist the test engineers in the design of a shroud which is optimized to receive the maximum cold X-ray radiation through its aperture while minimizing the hydrodynamic damage to the rest specimens. The analytical treatment uses mass conversion and the assumption of a liner velocity profile to assess the dynamic behavior of the developing wavefront. This technique provides a first estimate of the gas motion and pressure pulse and indicates some general trends of the hydrodynamic phenomenon. 9 refs., 16 figs., 1 tab.
NASA has proposed that the solar concentrator for the manned space station, referred to as the Solar Concentrator Advanced Development (SCAD) dish, undergo terrestrial testing prior to being deployed in space. Because reliable flight concentrator performance is so important, independent tests of the SCAD concentrator are needed to demonstrate the offset parabolic concept and validate the computer codes needed for predicting concentrator flux profile and power generating capability. This report documents the first phase of a three-phase project to test the SCAD concentrator on sun. The three phases of the project are (1) Feasibility of On-Sun Testing; (2) Detailed Design and Fabrication of Test Fixtures; and (3) Testing and Analysis of Results. The objectives of Phase 1 are to evaluate the feasibility of testing the concentrator on sun in a terrestrial environment and to determine the potential for accurately predicting its performance in space. The feasibility study includes: an evaluation of terrestrial structures to support and track the concentrator; an assessment of methods for protecting the concentrator from the environment when it is not on test; the selection of the most feasible support structure and protection system; an evaluation of the effects of terrestrial solar power levels and sunshapes on the verification of computer codes for predicting the on-orbit performance of the concentrator; the development of a preliminary test plan complete with procedures and instrumentation; and the development of schedule and cost estimates for Phases 2 and 3 of the project.
This report describes a computer-controlled densitometer and software designed for qualitative and semiquantitative analyses of photographically recorded atomic emission spectra. The instrument provides a number of operational features and unique capabilities for spectrochemical analyses. The purpose of this research was the evaluation of the automated densitometer system and computer algorithms for identifying and measuring atomic emission spectra from photographs. 11 refs., 10 figs., 5 tabs.
We have obtained Raman spectra of icosahedral boron-rich solids. The spectra of α-rhombohedral boron, boron arsenide, and boron phosphide are consistent with highly-ordered materials. Polarization studies have resulted in symmetry assignments for most of the Raman bands of α-rhombohedral boron. In contrast, the Raman spectra of the boron carbides reveal local substitutional disorder. They also change progressively as a function of carbon content. A structural model for the boron carbides has been developed to explain the Raman and infrared absorption spectra, x-ray data, and electrical and thermal transport properties. Raman spectra of boron carbide samples enriched in 10B, 11B, and 13C reveal details of the atomic motions. The vibrational frequencies and exceptionally narrow linewidths of certain Raman modes are discussed in terms of a ‘‘strong’’ bond model. In this model certain vibrational modes involving relatively stiff bonds between chain atoms, chain and icosahedral atoms, and atoms on different icosahedra are decoupled from the boride lattice by weak, intraicosahedral bonds.
The Small-Scale Mine-By was an in situ experiment to measure changes in brine and gas permeability of rock salt as a result of nearby excavation. A series of small-volume pressurized brine- and gas-filled test intervals were established 8 m beneath the floor of Room L1 in the WIPP underground. The test intervals were isolated in the bottom of the 4.8-cm diameter monitoring boreholes with inflatable rubber packers, and are initially pressurized to about 2 MPa. Both brine- and gas-filled test intervals were located 1.25, 1.5, 2, 3, and 4 r from the center of a planned large-diameter hole, where r is the radius of the large-diameter hole. Prior to the drilling of the large-diameter borehole, the responses of both the brine- and gas-filled test intervals were consistent with the formation modeled as a very low permeability, low porosity porous medium with a significant pore (brine) pressure and no measurable gas permeability. The drilling of the mine-by borehole created a zone of dilated, partially saturated rock out to about 1.5 r. The formation pressure increases from near zero at 1.5 r to the pre-excavation value at 4 r. Injection tests reveal a gradient of brine permeabilities from 5 {times} 10{sup {minus}18} m{sup 2} at 1.25 r to about the pre-excavation value (10{sup {minus}21} m{sup 2}) by 3 r. Gas-injection tests reveal measurable gas permeability is limited to within 1.5 r. 17 refs., 24 figs., 6 tabs.
A fractured porous medium is often modeled as a dual porosity system. The subsystems of fractures and matrix pores are assumed to provide two flow continuums. This is especially true when considering solute transport through such a system. Coupling terms are then required to enable the calculation of the exchange of solute between the two subsystems. The coupling terms for solute transport through a fractured medium are derived in this report. This report then investigates the need for the dual porosity models for solute transport. It is shown that the complexity of a dual porosity model is required in some cases to accurately represent the solute motion. However, it is also shown that some situations can be well represented by approximate single porosity models if certain criteria are met. A single porosity model allows the use of analytical solutions. Sample calculations are presented using parameter values representative of Yucca Mountain tuffs. These calculations show that a dual porosity model is not required to model solute transport at Yucca Mountain if the water fluxes are as low as currently believed. 39 refs., 10 figs., 2 tabs.
Sandia National Laboratories, has developed a methodology for performance assessment of deep geologic disposal of high-level nuclear waste. The applicability of this performance assessment methodology has been demonstrated for disposal in bedded salt and basalt; it has since been modified for assessment of repositories in unsaturated, fractured tuff. Changes to the methodology are primarily in the form of new or modified ground water flow and radionuclide transport codes. A new computer code, DCM3D, has been developed to model three-dimensional ground-water flow in unsaturated, fractured rock using a dual-continuum approach. The NEFTRAN 2 code has been developed to efficiently model radionuclide transport in time-dependent velocity fields, has the ability to use externally calculated pore velocities and saturations, and includes the effect of saturation dependent retardation factors. In order to use these codes together in performance-assessment-type analyses, code-coupler programs were developed to translate DCM3D output into NEFTRAN 2 input. Other portions of the performance assessment methodology were evaluated as part of modifying the methodology for tuff. The scenario methodology developed under the bedded salt program has been applied to tuff. An investigation of the applicability of uncertainty and sensitivity analysis techniques to non-linear models indicate that Monte Carlo simulation remains the most robust technique for these analyses. No changes have been recommended for the dose and health effects models, nor the biosphere transport models. 52 refs., 1 fig.
The governing equation for steady flow in a partially saturated, porous medium can be written in a linear form if one adopts a hydraulic conductivity function that is exponential in the capillary-pressure head. The resulting linear field equation is well suited to numerical solution by the boundary integral equation method (BIEM). The exponential conductivity function is compared to a more complex form often assumed for tuffs, and is found to be a reasonable approximation over limited ranges of pressure head. A computer code based on the BIEM is described and tested. The BIEM is found to exhibit quadratic convergence with element size reduction on smooth solutions and on singular problems, if mesh grading is used. Agreement between results from the BIEM code an a finite-element code that solves the fully nonlinear problem is excellent, and is achieved at a substantial advantage in computer processing time. 26 refs., 23 figs., 8 tabs.
The development of the present United States standards for transuranic and high-level waste fundamental criteria, derived release limits, and risk limits for probabilistic releases is traced through supporting documentation. The development procedures and the resulting regulations are compared to requirements for the standards, traditional methods of regulating chemical and radiological carcinogens, and recommendations made by the International Commission on Radiological Protection, the Science Advisory Board, the Nuclear Waste Technical Review Board, and individual investigators. The development methodology, logic, assumptions, and models are reviewed relative to the two proposed repositories. Individual difficulties are defined, and their probable causes and potential effects are examined. Several options are suggested for modifying and extending the standards for each of the four major areas; these options make the standards more appropriate for the sites now under consideration, relate them more directly to the actual safety of the repositories, and make them more defensible. Many of the extensions are compatible with the present standards and would not require any significant changes in philosophy, methodology, or format. The benefits of an enhanced quality assurance program are discussed and several other changes in development procedures for waste disposal regulations are suggested. 49 refs., 17 figs., 4 tabs.
This document describes the method developed by Sandia National Laboratories (SNL) to evaluate transducer used in the design certification testing of nuclear material shipping packages. This testing project was performed by SNL for the Office of Civilian Radioactive Waste Management (OCRWM). This evaluation is based on the results of tests conducted to measure ruggedness, failure frequency, repeatability, and manufacturers' calibration data under both field and laboratory conditions. The results of these tests are provided and discussed. The transducer were selected for testing by surveying cask contractors and testing facilities. Important insights relating to operational characteristics of accelerometer types were gained during field testing. 11 refs., 105 figs., 16 tabs.
Recognizing the importance of nuclear license renewal to the nation's energy strategy, the Department of Energy (DOE) initiated a plant lifetime improvement program during 1985 to determine the feasibility of the license renewal option for US nuclear plants. Initial activities of the DOE program focused on determining whether there were technical and economic obstacles that might preclude or limit the successful implementation of the license renewal option. To make this determination, DOE cosponsored with the Electric Power Research Institute (EPRI) pilot-plant efforts by Virginia Electric Power and Northern States Power. Both pilot-plant efforts concluded that life extension is technically and economically feasible. In parallel with the pilot-plant activities, DOE performed national economic studies that demonstrated the economic desirability of life extension. Having demonstrated the feasibility of life extension, DOE, in conjunction with EPRI, selected two lead plants to demonstrate the license renewal process. These lead plants are Yankee Atomic's Yankee Rowe facility and Northern States Power's Monticello facility. DOE also initiated activities to develop the technical and regulatory bases to support the license renewal process in the United States. DOE has recently identified nuclear plant license renewal to be an important element of its National Energy Strategy. This paper summarizes the significant results, conclusions, and ongoing activities of the DOE effort.