Blanket Biological Review for General Maintenance Activities Within Active Burial Grounds, 200 E and 200 W Areas, ECR No.2001-200-048 (open access)

Blanket Biological Review for General Maintenance Activities Within Active Burial Grounds, 200 E and 200 W Areas, ECR No.2001-200-048

No plant and animal species protected under the ESA, candidates for such protection, or species listed by the Washington state government were observed in the vicinity of the proposed sites. Piper's daisy may still occur in some of the burial grounds. This is a Washington State Sensitive plant species, and as such is a Level III resource under the Hanford Site Biological Resources Management Plan. Compensatory mitigation is appropriate for this species when adverse impacts cannot be avoided. The Ecological Compliance Assessment Project (ECAP) staff should consulted prior to the initiation of major work activities within areas where this species has been identified (218-E-12, 218-E-10). The stalked-pod and crouching milkvetch are relatively common throughout 200 West area, therefore even if the few individuals within the active burial grounds are disturbed, it is not likely that the overall local population will be adversely affected. The Watch List is the lowest level of listing for plant species of concern in the State of Washington. No adverse impacts to species or habitats of concern are expected to occur from routine maintenance within the active portions of the 218-W-4C, 218-W-4B, 218-W-3, 218-W-3A, and 218-W-5 burial grounds, as well as the portion of 218-E-12B currently …
Date: May 8, 2002
Creator: Sackschewsky, Michael R.
Object Type: Report
System: The UNT Digital Library
EVALUATION OF THE MIGRATION POTENTIAL FOR 60Co AND 137Cs AT THE MAINE YANKEE SITE. (open access)

EVALUATION OF THE MIGRATION POTENTIAL FOR 60Co AND 137Cs AT THE MAINE YANKEE SITE.

The objective of this report is to discuss the degree of sorption and desorption of {sup 137}Cs and {sup 60}Co that may be associated with the granite bedrock and the ''popcorn'' cement drain system that underlie the Maine Yankee Containment Foundation. The purpose is to estimate how much retardation of these two radionuclides takes place in groundwater that flows in the near-field of the Containment Foundation, specifically with respect to contamination originating at the PAB Test Pit. Specific concerns revolve around the potential for the contamination originating near the PAB to create a radioactive dose to a hypothetical ''resident farmer'' using a well intercepting this water to exceed 4 millirems/yr.
Date: August 8, 2002
Creator: FUHRMANN,M. SULLIVAN,T.
Object Type: Report
System: The UNT Digital Library
Classification of Bent-Double Galaxies: Experiences with Ensembles of Decision Trees (open access)

Classification of Bent-Double Galaxies: Experiences with Ensembles of Decision Trees

In earlier work, we have described our experiences with the use of decision tree classifiers to identify radio-emitting galaxies with a bent-double morphology in the FIRST astronomical survey. We now extend this work to include ensembles of decision tree classifiers, including two algorithms developed by us. These algorithms randomize the decision at each node of the tree, and because they consider fewer candidate splitting points, are faster than other methods for creating ensembles. The experiments presented in this paper with our astronomy data show that our algorithms are competitive in accuracy, but faster than other ensemble techniques such as Boosting, Bagging, and Arcx4 with different split criteria.
Date: January 8, 2002
Creator: Kamath, C & Cantu-Paz, E
Object Type: Article
System: The UNT Digital Library
Chemistry at Extreme Conditions (open access)

Chemistry at Extreme Conditions

We present equation of state results from impulsively stimulated light scattering (ISLS) experiments conducted in diamond anvil cells on pure supercritical fluids. We have made measurements on fluid H{sub 2}O (water), and CH{sub 3}OH (methanol). Sound speeds measured through ISLS have allowed us to refine existing potential models used in the exponential-6 (EXP-6) detonation product library [Fried, L. E., and Howard, W. M., J. Chem. Phys. 109 (17): 7338-7348 (1998).]. The refined models allow us to more accurately assess the chemical composition at the Chapman-Jouget (C-J) state of common energetic materials. We predict that water is present in appreciable quantities at the C-J state of energetic materials HMX, RDX, and nitro methane.
Date: August 8, 2002
Creator: Zaug, J M; Fried, L E; Abramson, E H; Hansen, D W; Crowhurst, J C & Howard, W M
Object Type: Article
System: The UNT Digital Library
Stretchable Micro-Electrode Array (open access)

Stretchable Micro-Electrode Array

This paper focuses on the design consideration, fabrication processes and preliminary testing of the stretchable micro-electrode array. We are developing an implantable, stretchable micro-electrode array using polymer-based microfabrication techniques. The device will serve as the interface between an electronic imaging system and the human eye, directly stimulating retinal neurons via thin film conducting traces and electroplated electrodes. The metal features are embedded within a thin ({approx}50 micron) substrate fabricated using poly (dimethylsiloxane) (PDMS), a biocompatible elastomeric material that has very low water permeability. The conformable nature of PDMS is critical for ensuring uniform contact with the curved surface of the retina. To fabricate the device, we developed unique processes for metalizing PDMS to produce robust traces capable of maintaining conductivity when stretched (5%, SD 1.5), and for selectively passivating the conductive elements. An in situ measurement of residual strain in the PDMS during curing reveals a tensile strain of 10%, explaining the stretchable nature of the thin metalized devices.
Date: March 8, 2002
Creator: Maghribi, M.; Hamilton, J.; Polla, D.; Rose, K.; Wilson, T. & Krulevitch, P.
Object Type: Article
System: The UNT Digital Library
Pressure Loads by Gas in an Enclosed Chamber in DYNA3D (open access)

Pressure Loads by Gas in an Enclosed Chamber in DYNA3D

New algorithms that efficiently calculate the volume of a closed chamber are presented in this paper. The current pressure in the enclosed chamber can then be computed, based on the user-specified gas law, from the updated volume and the initial volume and pressure of the chamber. This pressure load function is very useful in modeling common features, such as air pocket, airbag, piston, and gun barrel, in structural analyses.
Date: August 8, 2002
Creator: Lin, J & Badders, D C
Object Type: Report
System: The UNT Digital Library
Natural Gas Storage in Basalt Aquifers of the Columbia Basin, Pacific Northwest USA: A Guide to Site Characterization (open access)

Natural Gas Storage in Basalt Aquifers of the Columbia Basin, Pacific Northwest USA: A Guide to Site Characterization

This report provides the technical background and a guide to characterizing a site for storing natural gas in the Columbia River Basalt
Date: August 8, 2002
Creator: Reidel, Steve P.; Spane, Frank A. & Johnson, Vernon G.
Object Type: Report
System: The UNT Digital Library
Image-Based Vehicle Identification Technology for Homeland Security Applications (open access)

Image-Based Vehicle Identification Technology for Homeland Security Applications

The threat of terrorist attacks against US civilian populations is a very real, near-term problem that must be addressed, especially in response to possible use of Weapons of Mass Destruction. Several programs are now being funded by the US Government to put into place means by which the effects of a terrorist attack could be averted or limited through the use of sensors and monitoring technology. Specialized systems that detect certain threat materials, while effective within certain performance limits, cannot generally be used efficiently to track a mobile threat such as a vehicle over a large urban area. The key elements of an effective system are an image feature-based vehicle identification technique and a networked sensor system. We have briefly examined current uses of image and feature recognition techniques to the urban tracking problem and set forth the outlines of a proposal for application of LLNL technologies to this critical problem. The primary contributions of the proposed work lie in filling important needs not addressed by the current program: (1) The ability to create vehicle ''fingerprints,'' or feature information from images to allow automatic identification of vehicles. Currently, the analysis task is done entirely by humans. The goal is to …
Date: October 8, 2002
Creator: Clark, G. A.
Object Type: Report
System: The UNT Digital Library
Changes in the vertical temperature structure associated with carbonaceous aerosols (open access)

Changes in the vertical temperature structure associated with carbonaceous aerosols

Carbonaceous aerosols from anthropogenic activities act to both scatter and absorb solar radiation. It has been postulated that absorption by aerosols might significantly alter both the vertical temperature structure of the atmosphere and cloud fraction [Hansen et al. 1997, Ackerman et al, 2000]. Since both effects may alter the assessment of climate change associated with human activities, it is very important to understand both the magnitude and the mechanism by which carbonaceous aerosols affect climate. In this paper, we used a coupled climate and chemistry transport model to estimate the effects of carbonaceous aerosols on the vertical temperature structure and their effects on cloud fraction. A series Of control simulations were also carried out to compare the results of the model in which carbonaceous aerosols interact with climate with those in which they do not. We will present the temperature difference between simulations that include the effect of black carbon on the radiation field and those that do not, both at the surface and in the free troposphere. We will also discuss the change of temperature lapse rate and changes of cloud fraction associated with black carbon.
Date: February 8, 2002
Creator: Zhang, Y.; Penner, J. E.; Chuang, C. C.; Santer, B. D. & Taylor, K.
Object Type: Article
System: The UNT Digital Library
Study of the Direct Oxidation of Methane in Solid Oxide Fuel Cells (open access)

Study of the Direct Oxidation of Methane in Solid Oxide Fuel Cells

Solid oxide fuel cells (SOFCs) are electrochemical devices that have received great interest recently because of their promise for clean and efficient power generation. Since SOFCs generate electricity directly through electrochemical processes that do not involve combustion, fuel cells are not limited by the Carnot cycle and thus, very high efficiency can be achieved. For instance, current state-of-the-art fuel cells can reach 50% efficiency while that of conventional power generation devices are generally below 30%. The high efficiency is a key mean that will enable the use of fossil fuels at reduced carbon emissions. The ideal fuel for fuel cells is hydrogen. However, hydrogen is not available directly in nature but must be made using another fossil fuel and/or energy sources. For the immediate future, except for a few niche markets, fuel cells will have to use hydrocarbons as fuel. The ideal hydrocarbon fuel would be natural gas since a natural gas infrastructure readily exists. Natural gas has indeed been used to run various fuel cells. However, natural gas cannot be used directly as a fuel for fuel cells because of its low reactivity. Natural gas must be converted to more reactive components, typically to carbon monoxide and hydrogen via …
Date: February 8, 2002
Creator: Pham, A. Q.
Object Type: Report
System: The UNT Digital Library
Uranyl-Fluoride (235U) Solutions in Spherical Stainless Steel Vessels with Reflectors of Be, Ch2 and Be-Ch2 Composites, Part II (open access)

Uranyl-Fluoride (235U) Solutions in Spherical Stainless Steel Vessels with Reflectors of Be, Ch2 and Be-Ch2 Composites, Part II

A series of criticality studies were performed at the Lawrence Livermore National Laboratory in the late 1950's using aqueous solutions of {sup 233}U in the form of UO{sub 2}F{sub 2} stabilized with 0.3% by weight of HF. These experiments were assigned the program name Falstaff. The {sup 233}U concentration in these experiments ranged from 0.13 to 0.87 kg/l. Eight type 347 stainless steel spheres ranging in inner radius from 7.87 to 12.45 cm were available for use as containers for the solutions. The scope of this evaluation is limited to the experiments involving the four lowest concentrations of uranyl-fluoride solution with 0.45, 0.37, 0.24 and 0.13 kg ({sup 233}U)/l. Reflectors of beryllium, polyethylene and beryllium-polyethylene composites were used. Thirty-one configurations are evaluated and accepted as criticality-safety benchmark models. Fission rate data calculated by the evaluator (see Appendix B) show that twenty-six of these configurations have over 50% of the fissions occurring in the thermal energy range and these configurations are therefore classified as ''THERMAL''. Five of the configurations have less than 50% of the fissions occurring in any of the fast, intermediate or thermal energy range and therefore are classified as ''MIXED''.
Date: April 8, 2002
Creator: Heinrichs, D
Object Type: Article
System: The UNT Digital Library
Large Scale Atmospheric Chemistry Simulations for 2001: An Analysis of Ozone and Other Species in Central Arizona (open access)

Large Scale Atmospheric Chemistry Simulations for 2001: An Analysis of Ozone and Other Species in Central Arizona

A key atmospheric gas is ozone. Ozone in the stratosphere is beneficial to the biosphere because it absorbs a significant fraction of the sun's shorter wavelength ultraviolet radiation. Ozone in the troposphere is a pollutant (respiratory irritant in humans and acts to damage crops, vegetation, and many materials). It affects the Earths energy balance by absorbing both incoming solar radiation and outgoing long wave radiation. An important part of the oxidizing capacity of the atmosphere involves ozone, through a photolysis pathway that leads to the hydroxyl radical (OH). Since reaction with OH is a major sink of many atmospheric species, its concentration controls the distributions of many radiatively important species. Ozone in the troposphere arises from both in-situ photochemical production and transport from the stratosphere. Within the troposphere, ozone is formed in-situ when carbon monoxide (CO), methane (CH4), and non-methane hydrocarbons (NMHCs) react in the presence of nitrogen oxides (NO, = NO + NO2) and sunlight. The photochemistry of the stratosphere differs significantly from that in the troposphere. Within the stratosphere, ozone formation is initiated by the photolysis of 02. Stratospheric ozone may be destroyed via catalytic reactions with NO, H (hydrogen), OH, CI (chlorine) and Br (bromine), or photolysis. …
Date: October 8, 2002
Creator: Atherton, C; Bergmann, D; Cameron-Smith, P; Connell, P; Molenkamp, C; Rotman, D et al.
Object Type: Article
System: The UNT Digital Library
Comparison of Anti-Reflective Coated and Uncoated Surfaces Figured by Pitch-Polishing and Magneto-Rheological Processes (open access)

Comparison of Anti-Reflective Coated and Uncoated Surfaces Figured by Pitch-Polishing and Magneto-Rheological Processes

When completed, the National Ignition Facility (NIF) will provide laser energies in the Mega-joule range. Successful pulse amplification to these extremely high levels requires that all small optics, found earlier in the beamline, have stringent surface and laser fluence requirements. In addition, they must operate reliably for 30 years constituting hundreds of thousands of shots. As part of the first four beamlines, spherical and aspherical lenses were required for the beam relaying telescopes. The magneto-rheological technique allows for faster and more accurate finishing of aspheres. The spherical and aspherical lenses were final figured using both conventional-pitch polishing processes for high quality laser optics and the magneto-rheological finishing process. The purpose of this paper is to compare the surface properties between these two finishing processes. Some lenses were set aside from production for evaluation. The surface roughness in the mid-frequency range was measured and the scatter was studied. Laser damage testing at 1064 nm (3-ns pulse width) was performed on surfaces in both the uncoated and coated condition.
Date: November 8, 2002
Creator: Chow, R.; Thomas, M. D.; Bickel, R. & Taylor, J. R.
Object Type: Article
System: The UNT Digital Library
Thick Liquid-Walled Spheromak Magnetic Fusion Power Plant (open access)

Thick Liquid-Walled Spheromak Magnetic Fusion Power Plant

We assume a spheromak configuration can be made and sustained by a steady gun current, which injects particles, current and magnetic field, i.e., helicity injection. The equilibrium is calculated with an MHD equilibrium code, where an average beta of 10% is found. The toroidal current of 40 MA is sustained by an injection current of 100 kA (125 MW of gun power). The flux linking the gun is 1/1000th that of the flux in the spheromak. The geometry allows a flow of liquid, either molten salt, (flibe-Li{sub 2}BeF{sub 4} or flinabe-LiNaBeF{sub 4}) or liquid metal such as SnLi which protects most of the walls and structures from neutron damage. The free surface between the liquid and the burning plasma is heated by bremsstrahlung and optical radiation and neutrons from the plasma. The temperature of the free surface of the liquid is calculated and then the evaporation rate is estimated. The impurity concentration in the burning plasma is estimated and limited to a 20% reduction in the fusion power. For a high radiating edge plasma, the divertor power density of 460 MW/m{sup 2} is handled by high-speed (20 m/s), liquid jets. For low radiating edge plasmas, the divertor-power density of 1860 …
Date: April 8, 2002
Creator: Moir, R W; Bulmer, R H; Fowler, T K & Youssef, M Z
Object Type: Report
System: The UNT Digital Library
Model simulations of the first aerosol indirect effect and comparison of cloud susceptibility fo satellite measurements (open access)

Model simulations of the first aerosol indirect effect and comparison of cloud susceptibility fo satellite measurements

Present-day global anthropogenic emissions contribute more than half of the mass in submicron particles primarily due to sulfate and carbonaceous aerosol components derived from fossil fuel combustion and biomass burning. These anthropogenic aerosols modify the microphysics of clouds by serving as cloud condensation nuclei (CCN) and enhance the reflectivity of low-level water clouds, leading to a cooling effect on climate (the Twomey effect or first indirect effect). The magnitude of the first aerosol indirect effect is associated with cloud frequency as well as a quantity representing the sensitivity of cloud albedo to changes in cloud drop number concentration. This quantity is referred to as cloud susceptibility [Twomey, 1991]. Analysis of satellite measurements demonstrates that marine stratus clouds are likely to be of higher susceptibility than continental clouds because of their lower number concentrations of cloud drops [Platnick and Twomey, 1994]. Here, we use an improved version of the fully coupled climate/chemistry model [Chuang et al., 1997] to calculate the global concentrations Of sulfate, dust, sea salt, and carbonaceous aerosols (biomass smoke and fossil fuel organic matter and black carbon). We investigated the impact of anthropogenic aerosols on cloud susceptibility and calculated the associated changes of shortwave radiative fluxes at the …
Date: March 8, 2002
Creator: Chuang, C.; Penner, J. E. & Kawamoto, K.
Object Type: Article
System: The UNT Digital Library
Disabling Radiological Dispersal Terror (open access)

Disabling Radiological Dispersal Terror

Terror resulting from the use of a radiological dispersal device (RDD) relies upon an individual's lack of knowledge and understanding regarding its significance. Disabling this terror will depend upon realistic reviews of the current conservative radiation protection regulatory standards. It will also depend upon individuals being able to make their own informed decisions merging perceived risks with reality. Preparation in these areas will reduce the effectiveness of the RDD and may even reduce the possibility of its use.
Date: November 8, 2002
Creator: Hart, M.
Object Type: Article
System: The UNT Digital Library
Field and Current Amplification in the SSPX Spheromak (open access)

Field and Current Amplification in the SSPX Spheromak

Results are presented from experiments relating to magnetic field generation and current amplification in the SSPX spheromak. The SSPX spheromak plasma is driven by DC coaxial helicity injection using a 2MJ capacitor bank. Peak toroidal plasma currents of up to 0.7MA and peak edge poloidal fields of 0.3T are produced; lower current discharges can be sustained up to 3.5msec. When edge magnetic fluctuations are reduced below 1% by driving the plasma near threshold, it is possible to produce plasmas with Te > 150eV, <{beta}{sub e}>-4% and core {chi}{sub e} {approx} 30m{sup 2}/s. Helicity balance for these plasmas suggests that sheath dissipation can be significant, pointing to the importance of maximizing the voltage on the coaxial injector. For most operational modes we find a stiff relationship between peak spheromak field and injector current, and little correlation with plasma temperature, which suggests that other processes than ohmic dissipation may limit field amplification. However, slowing spheromak buildup by limiting the initial current pulse increases the ratio of toroidal current to injected current and points to new operating regimes with more favorable current amplification.
Date: October 8, 2002
Creator: Hill, D. N.; Blumer, R. H.; Cohen, B. I.; Hooper, E. B.; McLean, H. S.; Moller, J. et al.
Object Type: Article
System: The UNT Digital Library
SLURM: Simple Linux Utility for Resource Management (open access)

SLURM: Simple Linux Utility for Resource Management

Simple Linux Utility for Resource Management (SLURM) is an open source, fault-tolerant, and highly scalable cluster management and job scheduling system for Linux clusters of thousands of nodes. Components include machine status, partition management, job management, scheduling and stream copy modules. The design also includes a scalable, general-purpose communication infrastructure. This paper presents a overview of the SLURM architecture and functionality.
Date: July 8, 2002
Creator: Jette, Morris A.; Dunlap, Chris; Garlick, Jim & Grondona, Mark
Object Type: Text
System: The UNT Digital Library
Recent Advances in Indirect Drive ICF Target Physics (open access)

Recent Advances in Indirect Drive ICF Target Physics

In preparation for ignition on the National Ignition Facility, the Lawrence Livermore National Laboratory's Inertial Confinement Fusion Program, working in collaboration with Los Alamos National Laboratory, Commissariat a lEnergie Atomique (CEA), and Laboratory for Laser Energetics at the University of Rochester, has performed a broad range of experiments on the Nova and Omega lasers to test the fundamentals of the NIF target designs. These studies have refined our understanding of the important target physics, and have led to many of the specifications for the NIF laser and the cryogenic ignition targets. Our recent work has been focused in the areas of hohlraum energetics, symmetry, shock physics, and target design optimization & fabrication.
Date: October 8, 2002
Creator: Hammel, B.; Lindl, J.; Amendt, P. A.; Bernat, G. W.; Collins, G. W.; Glenzer, S. H. et al.
Object Type: Article
System: The UNT Digital Library
Processes the Govern Helicity Injection in the SSPX Spheromak (open access)

Processes the Govern Helicity Injection in the SSPX Spheromak

The physical processes that govern the gun-voltage and give rise to field generation by helicity injection are surveyed in the Sustained Spheromak Physics experiment (SSPX) using internal magnetic field probes and particular attention to the gun-voltage. SSPX is a gun-driven spheromak, similar in many respects to CTX, although differing substantially by virtue of a programmable vacuum field configuration. Device parameters are: diameter = 1m, I{sub tor}-400kA, T{sub e}{approx}120eV, t{sub pulse}{approx}3ms. SSPX is now in its third year of operation and has demonstrated reasonable confinement (core {chi}{sub e}{approx}30m{sup 2}/s), and evidence for a beta limit (<{beta}{sub e}>{sub vol}{approx}4%), suggesting that the route to high temperature is to increase the spheromak field-strength (or current amplification, A{sub I} = I{sub torr}/I{sub inj}). Some progress has been made to increase A{sub I} in SSPX (A{sub I} = 2.2), although the highest A{sub I} observed in a spheromak of 3 has yet to be beaten. We briefly review helicity injection as the paradigm for spheromak field generation. SSPX results show that the processes that give efficient injection of helicity are inductive, and that these processes rapidly terminate when the current path ceases to change. The inductive processes are subsequently replaced by ones that resistively dissipate …
Date: October 8, 2002
Creator: Woodruff, S; Stallard, B W; Holcomb, C T & Cothran, C
Object Type: Article
System: The UNT Digital Library
Suppressing Anomalous Localized Waffle Behavior in Least Squares Wavefront Reconstructors (open access)

Suppressing Anomalous Localized Waffle Behavior in Least Squares Wavefront Reconstructors

A major difficulty with wavefront slope sensors is their insensitivity to certain phase aberration patterns, the classic example being the waffle pattern in the Fried sampling geometry. As the number of degrees of freedom in AO systems grows larger, the possibility of troublesome waffle-like behavior over localized portions of the aperture is becoming evident. Reconstructor matrices have associated with them, either explicitly or implicitly, an orthogonal mode space over which they operate, called the singular mode space. If not properly preconditioned, the reconstructor's mode set can consist almost entirely of modes that each have some localized waffle-like behavior. In this paper we analyze the behavior of least-squares reconstructors with regard to their mode spaces. We introduce a new technique that is successful in producing a mode space that segregates the waffle-like behavior into a few ''high order'' modes, which can then be projected out of the reconstructor matrix. This technique can be adapted so as to remove any specific modes that are undesirable in the final reconstructor (such as piston, tip, and tilt for example) as well as suppress (the more nebulously defined) localized waffle behavior.
Date: October 8, 2002
Creator: Gavel, D
Object Type: Article
System: The UNT Digital Library
Estimating Equivalency of Explosives Through A Thermochemical Approach (open access)

Estimating Equivalency of Explosives Through A Thermochemical Approach

The Cheetah thermochemical computer code provides an accurate method for estimating the TNT equivalency of any explosive, evaluated either with respect to peak pressure or the quasi-static pressure at long time in a confined volume. Cheetah calculates the detonation energy and heat of combustion for virtually any explosive (pure or formulation). Comparing the detonation energy for an explosive with that of TNT allows estimation of the TNT equivalency with respect to peak pressure, while comparison of the heat of combustion allows estimation of TNT equivalency with respect to quasi-static pressure. We discuss the methodology, present results for many explosives, and show comparisons with equivalency data from other sources.
Date: July 8, 2002
Creator: Maienschein, J L
Object Type: Article
System: The UNT Digital Library
Aerodynamic Design of Heavy Vehicles Reporting Period April 15, 2002 Through July 15, 2002 (open access)

Aerodynamic Design of Heavy Vehicles Reporting Period April 15, 2002 Through July 15, 2002

Activities for this quarter include an effort to simulate the flow structure in the wake region of the trailer and in the gap region between the tractor and the trailer for the GTS geometry. Two-dimensional simulations have been conducted on both flow structures using LLNL's ALE3D code. With the information obtained from these calculations, three-dimensional (3D) grids are constructed for the wake and the gap regions. Due to complexity of the required grid generation, two different grid generation tools have been utilized. The ALE3D code and NASA's Overflow code are both being used for the 3D simulations; ALE3D for large-eddy simulation and Overflow for Reynolds-averaged Navier-Stokes simulations. The wake results will be compared to the NASA 7 x 10 wind tunnel experiment and the gap results to the USC gap flow experiment. The NASA 7 x 10 wind tunnel simulation has been finalized with two different grid topologies. These results will provide the proper boundary conditions needed for the GTS in the tunnel flow simulations. Significant progress has been made in understanding and applying the NASA's Overflow code and the overset grid technology. In addition, we continue to implement advanced algorithms in LLNL's models to improve simulation speed and accuracy …
Date: August 8, 2002
Creator: McCallen, R.; Salari, K.; Ortega, J.; Yen-Nakafuji, D.; Dunn, T.; Browand, F. et al.
Object Type: Report
System: The UNT Digital Library
Coupled THM Simulations of the Drift Scale Test at Yucca Mountain (open access)

Coupled THM Simulations of the Drift Scale Test at Yucca Mountain

This paper presents a coupled thermal-hydrological-mechanical (THM) analysis of the Drift Scale Test (DST) conducted at Yucca Mountain, Nevada. The DST is a large-scale, long-term thermal test designed to investigate coupled thermal-mechanical-hydrological-chemical behavior in a fractured, welded tuff rock mass in support of nuclear waste isolation efforts. The model used for this analysis utilizes temperature distributions predicted by a thermal-hydrological code as input to a distinct element thermal mechanical code. This paper presents a brief discussion of the test and the coupled model, followed by comparison of predicted and measured displacements. Results show that the model predicts the trend and magnitude of the displacements observed in a cross section monitored in the test through four years of heating. Maximum principal stress levels of 60 MPa are predicted in the crown and floor of the heated drift (HD) after 4 years of heating. Comparison of predicted and observed displacements shows that the model closely predicts vertical displacement above the HD and provides a good estimate of horizontal displacement perpendicular to the HD. These results indicate that a thermal expansion coefficient of 9e-6/{Lambda}C is generally appropriate for the rockmass forming this test. Normal displacements on joints in the cross section examined here …
Date: March 8, 2002
Creator: Blair, S. C.; Carlson, S. R.; Lee, K. & Wagoner, J. L.
Object Type: Article
System: The UNT Digital Library