Publications

Calculations of water flow through Yucca Mountain show significant dryout and water perching in the vicinity of the proposed nuclear waste repository. These calculations also show that the extent of the dryout and perched water zones is a strong function of the material characteristics which are used to represent the fracture zones. The results show that for 100 {mu}m fracture case appreciable dryout and perched regions exist. When 1 {mu}m fractures are used no dryout or perched regions are calculated.

An integral part of the licensing procedure for the potential nuclear waste repository at Yucca Mountain, Nevada involves accurate prediction of the in situ rheology for design and construction of the facility and emplacement of the canisters containing radioactive waste. The data required as input to successful thermal and mechanical models of the behavior of the repository and surrounding lithologies include bulk density, grain density, porosity, compressional and shear wave velocities, elastic moduli, and compressional and tensile strengths. In this study a suite of experiments was performed on cores recovered from the USW-NRG-6 borehole drilled to support the Exploratory Studies Facility (ESF) at Yucca Mountain. USW-NRG-6 was drilled to a depth of 1100 feet through four thermal/mechanical units of Paintbrush tuff. A large data set has been collected on specimens recovered from borehole USW-NRG-6. Analysis of the results of these experiments showed that there is a correlation between fracture strength, Young`s modulus, compressional wave velocity and porosity. Additional scaling laws relating; static Young`s modulus and compressional wave velocity; and fracture strength and compressional wave velocity are promising. Since there are no other distinct differences in material properties, the scatter that is present at each fixed porosity suggests that the differences in the observed property can be related to the pore structure of the specimen. Image analysis of CT scans performed on each test specimen are currently underway to seek additional empirical relations to aid in refining the correlations between static and dynamic properties of tuff.

One of the critical issues facing the Yucca Mountain site characterization and performance assessment programs is the manner in which property scaling is addressed. Property scaling becomes an issue whenever heterogeneous media properties are measured at one scale but applied at another. A research program has been established to challenge current understanding of property scaling with the aim of developing and testing models that describe scaling behavior in a quantitative manner. Scaling of constitutive rock properties is investigated through physical experimentation involving the collection of suites of gas-permeability data measured over a range of discrete scales. The approach is to systematically isolate those factors believed to influence property scaling and investigate their relative contributions to overall scaling behavior. Two blocks of tuff, each exhibiting differing heterogeneity structure, have recently been examined. Results of the investigation show very different scaling behavior, as exhibited by changes in the distribution functions and variograms, for the two tuff samples. Even for the relatively narrow range of measurement scales employed significant changes in the distribution functions, variograms, and summary statistics occurred. Because such data descriptors will likely play an important role in calculating effective media properties, these results demonstrate both the need to understand and accurately model scaling behavior.

Improvements have been made to the fracture-flow model being used in the total-system performance assessment of a potential high-level radioactive waste repository at Yucca Mountain, Nevada. The ``weeps model`` now includes (1) weeps of varied sizes, (2) flow-pattern fluctuations caused by climate change, and (3) flow-pattern perturbations caused by repository heat generation. Comparison with the original weeps model indicates that allowing weeps of varied sizes substantially reduces the number of weeps and the number of containers contacted by weeps. However, flow-pattern perturbations caused by either climate change or repository heat generation greatly increases the number of containers contacted by weeps. In preliminary total-system calculations, using a phenomenological container-failure and radionuclide-release model, the weeps model predicts that radionuclide releases from a high-level radioactive waste repository at Yucca Mountain will be below the EPA standard specified in 40 CFR 191, but that the maximum radiation dose to an individual could be significant. Specific data from the site are required to determine the validity of the weep-flow mechanism and to better determine the parameters to which the dose calculation is sensitive.

Indicator geostatistical techniques have been used to produce a number of fully three-dimensional stochastic simulations of large-scale lithologic categories at the Yucca Mountain site. Each realization reproduces the available drill hole data used to condition the simulation. Information is propagated away from each point of observation in accordance with a mathematical model of spatial continuity inferred through soft data taken from published geologic cross sections. Variations among the simulated models collectively represent uncertainty in the lithology at unsampled locations. These stochastic models succeed in capturing many major features of welded-nonwelded lithologic framework of Yucca Mountain. However, contacts between welded and nonwelded rock types for individual simulations appear more complex than suggested by field observation, and a number of probable numerical artifacts exist in these models. Many of the apparent discrepancies between the simulated models and the general geology of Yucca Mountain represent characterization uncertainty, and can be traced to the sparse site data used to condition the simulations. Several vertical stratigraphic columns have been extracted from the three-dimensional stochastic models for use in simplified total-system performance assessment exercises. Simple, manual adjustments are required to eliminate the more obvious simulation artifacts and to impose a secondary set of deterministic geologic features on the overall stratigraphic framework provided by the indictor models.

Laboratory experiments were performed to measure the effect of frequency, water-saturation, and strain amplitude on Young`s modulus and seismic wave attenuation on rock cores recovered on or near the site of a potential nuclear waste repository at Yucca Mountain, Nevada. The purpose of this investigation is to perform the measurements using four techniques: cyclic loading, waveform inversion, resonant bar, and ultrasonic velocity. The measurements ranged in frequency between 10{sup {minus}2} and 10{sup 6} Hz. For the dry specimens Young`s modulus and attenuation were independent of frequency; that is, all four techniques yielded nearly the same values for modulus and attenuation. For saturated specimens, a frequency dependence for both Young`s modulus and attenuation was observed. In general, saturation reduced Young`s modulus and increased seismic wave attenuation. The effect of strain amplitude on Young`s modulus and attenuation was measured using the cyclic loading technique at a frequency of 10{sup {minus}1} Hz. The effect of strain amplitude in all cases was small. For some rocks, such as the potential repository horizon of the Topopah Spring Member tuff (TSw2), the effect of strain amplitude on both attenuation and modulus was minimal.

An intensive laboratory investigation is being performed to determine the mechanical properties of tuffs for the Yucca Mountain Site Characterization Project (YMP). Most recently, experiments are being performed on tuff samples from a series of drill holes along the proposed alignment of the Exploratory Study Facilities (ESF) north ramp. Unconfined compression and indirect tension experiments are being performed and the results are being analyzed with the help of bulk property information. The results on samples from five of the drill holes are presented here. In general, the properties vary widely, but are highly dependent on the sample porosity.

I use a piece-wise linear approximation to the directed flux expressions for a flowing Maxwellian fluid to write down boundary conditions for the fluid description of a multicomponent plasma. These boundary conditions are sufficiently robust to treat particle reflection, surface reactions leading to secondary production, diffusion, and field-induced drift of charged species.

The optimization of UV laser remote sensing systems and the interpretation of the return signals from these systems require detailed absorption and fluorescence spectra for the species of interest. Multispectral fluorescence techniques additionally require a database of dispersed UV fluorescence excitation spectra. Excitation wavelengths between 250 and 400 nm and fluorescence wavelengths in the 200 to 700 nm range are of interest.

Current SNL CALIOPE modeling efforts have produced an initial model that addresses DIAL issues of wavelength, hardware design parameters, range evaluation, etc. Although this model is producing valuable results and will be used to support the planning and evaluations necessary for the first ground field experiment, it is expected to have limitations with the complex science issues that affect the CALIOPE program. In particular, the multi-dimensional effects of atmospheric turbulence, plume dynamics, speckle, etc., may be significant issues and must be evaluated in detail as the program moves to the detection of liquids and solids, longer ranges, and elevated platform environments. The goal of the integrated UV fluorescence/DIAL modeling effort is to build upon the knowledge obtained in developing and exercising the initial model to adequately support the future activities of this program. This paper will address the development of the integrated UV model, issues and limiting assumptions that may be needed in order to address the-complex phenomena involved, limits of expected performance, and the potential use of this model.

Infrared emission (IRE) spectra were obtained from two borophosphosilicate glass (BPSG) thin-film sample sets. The first set consisted of 21 films deposited on undoped silicon wafers, and the second set consisted of 9 films deposited on patterned and doped (product) wafers. The IRE data were empirically modeled using partial least-squares calibration to simultaneously quantify four BPSG thin-film properties. The standard errors of the determinations when modeling the 21 monitor wafers were

Throughout the Department of Energy (DOE) complex, sites protect themselves with intrusion detection systems. Some of these systems have sensors in remote areas. These sensors frequently alarm -- not because they have detected a terrorist skulking around the area, but because they have detected a horse, or a dog, or a bush moving in the breeze. Even though the local security force is 99% sure there is no real threat, they must assess each of these nuisance or false alarms. Generally, the procedure consists of dispatching an inspector to drive to the area and make an assessment. This is expensive in terms of manpower and the assessment is not timely. Often, by the time the inspector arrives, the cause of the alarm has vanished. A television camera placed to view the area protected by the sensor could be used to help in this assessment, but this requires the installation of high-quality cable, optical fiber, or a microwave link. Further, to be of use at the present time, the site must have had the foresight to have installed these facilities in the past and have them ready for use now. What is needed is a device to place between the television camera and a modem connecting to a low-bandwidth channel such as radio or a telephone line. This paper discusses the development of such a device: an Image Transmission System, or ITS.

We have developed a capability to make real time concentration measurements of individual chemicals in a complex mixture using a multispectral laser remote sensing system. Our chemical recognition and analysis software consists of three parts: (1) a rigorous multivariate analysis package for quantitative concentration and uncertainty estimates, (2) a genetic optimizer which customizes and tailors the multivariate algorithm for a particular application, and (3) an intelligent neural net chemical filter which pre-selects from the chemical database to find the appropriate candidate chemicals for quantitative analyses by the multivariate algorithms, as well as providing a quick-look concentration estimate and consistency check. Detailed simulations using both laboratory fluorescence data and computer synthesized spectra indicate that our software can make accurate concentration estimates from complex multicomponent mixtures, even when the mixture is noisy and contaminated with unknowns.

Prior to May 1992, field demonstrations of characterization technologies were performed at an uncontaminated site near the Chemical Waste Landfill. In mid-1992 through summer 1993, both non-intrusive and intrusive characterization techniques were demonstrated at the Chemical Waste Landfill. Subsurface and dry barrier demonstrations were started in summer 1993 and will continue into 1995. Future plans include demonstrations of innovative drilling, characterization and long-term monitoring, and remediation techniques. Demonstrations were also scheduled in summer 1993 at the Kirtland Air Force HSWA site and will continue in 1994. The first phase of the Thermal Enhanced Vapor Extraction System (TEVES) project occurred in April 1992 when two holes were drilled and vapor extraction wells were installed at the Chemical Waste Landfill. Obtaining the engineering design and environmental permits necessary to implement this field demonstration will take until early 1994. Field demonstration of the vapor extraction system will occur in 1994.

This paper will discuss the UV Laser Remote Sensing Data Acquisition and Control Subsystem being developed by Sandia National Laboratories in support of the CALIOPE program. Details include the control of active system elements including the laser and beam steering mirror, passive system elements including detectors and signal processing instrumentation, and the acquisition and transfer of data for archival and evaluation by the multivariate analysis algorithm. Using the LabVIEW design philosophy developed for laboratory testing as a baseline, this evolving subsystem will initially support the UV fluorescence calibration and background data collections planned at SNL and the October 1994 Ground Field Experiment at the Nevada Test Site. The subsystem will then be upgraded to support an integrated DIAL/fluorescence capability for the April 1995 Ground Field Experiment and the October 1995 Elevated Platform Field Experiment.

When the ACCORD Process introduced Pro/ENGINEER to Sandians several years ago, a new process for design/definition was implemented. Prior to ACCORD, engineers and draftsmen worked in the 2-D mode with a program caned ANVIL{reg_sign}, which had limited capabilities. Although the transition from 2-D modeling to 3-D modeling met with some resistance, most engineers have embraced this new concept with enthusiasm They are now able to work in the 3-D mode and at increased levels of productivity with appropriate time savings never achieved before. One area that Pro/ENGINEER is noted for that this report will concentrate on, is the powerful interface module with its wide selection of transfer file configurations. This allows the engineer to create parts or assemblies and transfer them to many different second party software packages whose vendors can provide the capability for stress analysis, rapid prototypes, virtual reality environments, or many other forms of advanced manufacturing modes of communication. The ACCORD Program has at its core, the Pro/ENGINEER program from Parametric Technology Inc. Included in the ACCORD program, are several supporting programs from other vendors to make this cooperation between software packages a reality. It is possible to create parts in Pro/ENG transfer those parts to another package that has the capability to analyze the parts for deficiencies, then optimize those parts, and allow for changes to be made. Also included in this report, are other packages closely tied to Pro/ENGINEER, but not necessarily supported under the ACCORD program. Some of these packages allow you to create very impressive video productions, or allow you to meander through a virtual reality scenario. All of these new software packages will give you a new perspective on performance. This report will show how some of these interfaces work, and how you can improve your productivity if you utilize the ACCORD program as it is implemented here at Sandia.

The implosion dynamics of compact wire arrays on Saturn are explored as a function of wire mass m, wire length {ell}, wire radii R, and radial power-flow feed geometry using the ZORK code. Electron losses and the likelihood of arcing in the radial feed adjacent the wire load are analyzed using the TWOQUICK and CYLTRAN codes. The physical characteristics of the implosion and subsequent thermal radiation production are estimated using the LASNEX code in one dimension. These analyses show that compact tungsten wire arrays with parameters suggested by D. Mosher and with a 21-nH vacuum feed geometry satisfy the empirical scaling criterion I/(M/{ell}) {approximately} 2 MA/(mg/cm) of Mosher for optimizing non-thermal radiation from z pinches, generate low electron losses in the radial feeds, and generate electric fields at the insulator stack below the Charlie Martin flashover limit thereby permitting full power to be delivered to the load. Under such conditions, peak currents of {approximately}5 MA can be delivered to wire loads {approximately}20 ns before the driving voltage reverses at the insulator stack, potentially allowing the m = 0 instability to develop with the subsequent emission of non-thermal radiation as predicted by the Mosher model.

A thickness-shear mode (TSM) resonator typically consists of a thin disk of AT-cut quartz with circular electrodes patterned on both sides. When connected to appropriate circuitry, the quartz crystal resonates at a frequency determined by the crystal thickness. Originally used to measure metal deposition in vacuum, the device has recently been used for measurements in liquid. Since the mass sensitivity of the resonator is nearly the same in liquids as in air or vacuum, the device can be used as a sensitive solution-phase microbalance. In addition, the sensitivity of the TSM resonator to contacting fluid properties enables it to function as a monitor for these properties. Under liquid loading, the change in frequency of the resonator/oscillator combination differs from the change in resonant frequency of the device. Either of these changes can be determined from an appropriate application of an equivalent-circuit model that describes the electrical characteristics of the liquid-loaded resonator.

Four general topics are covered in respect to the natural space radiation environment: (1) particles trapped by the earth`s magnetic field, (2) cosmic rays, (3) radiation environment inside a spacecraft, (4) laboratory radiation sources. The interaction of radiation with materials is described by ionization effects and displacement effects. Total-dose effects on MOS devices is discussed with respect to: measurement techniques, electron-hole yield, hole transport, oxide traps, interface traps, border traps, device properties, case studies and special concerns for commercial devices. Other device types considered for total-dose effects are SOI devices and nitrided oxide devices. Lastly, single event phenomena are discussed with respect to charge collection mechanisms and hard errors. (GHH)

Supercritical carbon dioxide is being explored as a waste minimization technique for separating oils, greases and solvents from solid waste. The containments are dissolved into the supercritical fluid and precipitated out upon depressurization. The carbon dioxide solvent can then be recycled for continued use. Definitions of the temperature, pressure, flowrate and potential co-solvents are required to establish the optimum conditions for hazardous contaminant removal. Excellent extractive capability for common manufacturing oils, greases, and solvents has been observed in both supercritical and liquid carbon dioxide. Solubility measurements are being used to better understand the extraction process, and to determine if the minimum solubility required by federal regulations is met.

A variety of new molecular modeling tools are now available for studying molecular structures and molecular interactions, for building molecular structures from simple components using analytical data, and for studying the relationship of molecular structure to the energy of bonding and non-bonding interactions. These are proving quite valuable in characterizing molecular structures and intermolecular interactions and in designing new molecules. This paper describes the application of molecular modeling techniques to a variety of materials problems, including the probable modecular structures of coals, lignins, and hybrid inorganic-organic-organic systems (silsesquioxanes), the intercalation of small gas molecules in fullerene crystals, the diffusion of gas molecules through membranes, and the design, structure and function of biomimetic and nanocluster catalysts.

A unique end-to-end LIDAR sensor model has been developed supporting the concept development stage of the CALIOPE UV DIAL and UV laser-induced-fluorescence (LIF) efforts. The model focuses on preserving the temporal and spectral nature of signals as they pass through the atmosphere, are collected by the optics, detected by the sensor, and processed by the sensor electronics and algorithms. This is done by developing accurate component sub-models with realistic inputs and outputs, as well as internal noise sources and operating parameters. These sub-models are then configured using data-flow diagrams to operate together to reflect the performance of the entire DIAL system. This modeling philosophy allows the developer to have a realistic indication of the nature of signals throughout the system and to design components and processing in a realistic environment. Current component models include atmospheric absorption and scattering losses, plume absorption and scattering losses, background, telescope and optical filter models, PMT (photomultiplier tube) with realistic noise sources, amplifier operation and noise, A/D converter operation, noise and distortion, pulse averaging, and DIAL computation. Preliminary results of the model will be presented indicating the expected model operation depicting the October field test at the NTS spill test facility. Indications will be given concerning near-term upgrades to the model.

The Department of Energy`s Utility-Scale Joint-Venture (USJV) Program was developed to help industry commercialize dish/engine electric systems. Sandia National Laboratories developed this program and has placed two contracts, one with Science Applications International Corporation`s Energy Projects Division and one with the Cummins Power Generation Company. In this paper we present the designs for the two dish/Stirling systems that are being developed through the USJV Program.

The Arc/Info GENERALIZE command implements the Douglas-Peucker algorithm, a well-regarded approach that preserves line ``character`` while reducing the number of points according to a tolerance parameter supplied by the user. The authors have developed an Arc Macro Language (AML) interface called MAGENCO that allows the user to browse workspaces, select a coverage, extract a sample from this coverage, then apply various tolerances to the sample. The results are shown in multiple display windows that are arranged around the original sample for quick visual comparison. The user may then return to the whole coverage and apply the chosen tolerance. They analyze the ergonomics of line simplification, explain the design (which includes an animated demonstration of the Douglas-Peucker algorithm), and discuss key points of the MAGENCO implementation.

A comparison of the KAMELEON Fire model to large-scale open pool fire experimental data is presented. The model was used to calculate large-scale JP-4 pool fires with and without wind, and with and without large objects in the fire. The effect of wind and large objects on the fire environment is clearly seen. For the pool fire calculations without any object in the fire, excellent agreement is seen in the location of the oxygen-starved region near the pool center. Calculated flame temperatures are about 200--300 K higher than measured. This results in higher heat fluxes back to the fuel pool and higher fuel evaporation rates (by a factor of 2). Fuel concentrations at lower elevations and peak soot concentrations are in good agreement with data. For pool fire calculations with objects, similar trends in the fire environment are observed. Excellent agreement is seen in the distribution of the heat flux around a cylindrical calorimeter in a rectangular pool with wind effects. The magnitude of the calculated heat flux to the object is high by a factor of 2 relative to the test data, due to the higher temperatures calculated. For the case of a large flat plate adjacent to a circular pool, excellent qualitative agreement is seen in the predicted and measured flame shapes as a function of wind.