The Influence of the In-Situ Clad Staining on the Corrosion of Zircaloy in PWR Water Environment (open access)

The Influence of the In-Situ Clad Staining on the Corrosion of Zircaloy in PWR Water Environment

Zircaloy cladding tubes strain in-situ during service life in the corrosive environment of a Pressurized Water Reactor for a variety of reasons. First, the tube undergoes stress free growth due to the preferential alignment of irradiation induced vacancy loops on basal planes. Positive strains develop in the textured tubes along prism orientations while negative strains develop along basal orientations (Reference (a)). Second, early in life, free standing tubes will often shrink by creep in the diametrical direction under the external pressure of the water environment, but potentially grow later in life in the diametrical direction once the expanding fuel pellet contacts the cladding inner wall (Reference (b)). Finally, the Zircaloy cladding absorbs hydrogen as a by product of the corrosion reaction (Reference (c)). Once above the solubility limit in Zircaloy, the hydride precipitates as zirconium hydride (References (c) through (j)). Both hydrogen in solid solution and precipitated as Zirconium hydride cause a volume expansion of the Zircaloy metal (Reference (k)). Few studies are reported on that have investigated the influence that in-situ clad straining has on corrosion of Zircaloy. If Zircaloy corrosion rates are governed by diffusion of anions through a thin passivating boundary layer at the oxide-to-metal interface (References …
Date: June 21, 2001
Creator: Kammenzind, B.F., Eklund, K.L. and Bajaj, R.
Object Type: Report
System: The UNT Digital Library
A Revised Magnitude and Distance Amplitude Correction (MDAC2) Procedure for Regional Seismic Discriminants: Theory and Testing at NTS (open access)

A Revised Magnitude and Distance Amplitude Correction (MDAC2) Procedure for Regional Seismic Discriminants: Theory and Testing at NTS

The Magnitude and Distance Amplitude Correction (MDAC; Taylor and Hartse, 1998; Taylor et al., 2002) procedure for correcting regional seismic amplitudes for seismic event identification has been modified to include more realistic earthquake source models and source scaling. In the MDAC2 formulation we generalize the Brune (1970) earthquake source spectrum to use a more physical apparent stress model that can represent non-constant stress-drop scaling. We also event include a parameter that allows for variable P-wave and S-wave comer frequency scaling, imposing some of the constraints of ratio correction techniques (Rodger and Walter, 2002). Very Stable moment magnitude measures (Mayeda et al., 2002) from regional coda wave envelopes that have been tied to independently derived regional seismic moments are incorporated. This eliminates two fitting parameters that were necessary in relating seismic moment to magnitude. The incorporation of Bayesian tomography to replace the assumption of a constant Q0 model is also described. These modifications allow for more flexibility in the MDAC grid-search procedure. The direct tie to regional seismic moment rather than body wave magnitude reduces effects of upper mantle bias on the corrected amplitudes. In this paper, we develop the theory and test the formulation on Nevada Test Site (NTS) data.
Date: December 21, 2001
Creator: Walter, W R & Taylor, S R
Object Type: Report
System: The UNT Digital Library
Infrared Spectra of High Pressure Carbon Monoxide (open access)

Infrared Spectra of High Pressure Carbon Monoxide

We report infrared (IR) spectroscopic measurements of carbon monoxide (CO) at high pressures. Although CO is one of the simplest heteronuclear diatomic molecules, it displays surprisingly complex behavior at high pressures and has been the subject of several studies [1-5]. IR spectroscopic studies of high pressures phases of CO provide data complementing results from previous studies and elucidating the nature of these phases. Though a well-known and widely utilized diagnostic of molecular systems, IR spectroscopy presents several experimental challenges to high pressure diamond anvil cell research. We present measurements of the IR absorption bands of CO at high pressures and experimentally illustrate the crucial importance of accurate normalization of IR spectra specially within regions of strong absorptions in diamond.
Date: September 21, 2001
Creator: Evans, W. J.; Lipp, M. J. & Lorenzana, H. E.
Object Type: Article
System: The UNT Digital Library
Coarse-Grained Molecular Dynamics and Multiscale Modeling of NEMS Resonators (open access)

Coarse-Grained Molecular Dynamics and Multiscale Modeling of NEMS Resonators

We review concurrent multiscale simulations of dynamic and temperature-dependent processes found in nanomechanical systems coupled to larger scale surroundings. We focus on the behavior of sub-micron Micro-Electro-Mechanical Systems (MEMS), especially microresonators. These systems are often called NEMS, for Nano-Electro-Mechanical Systems. The coupling of length scales methodology we have developed for MEMS employs an atomistic description of small but key regions of the system, consisting of millions of atoms, coupled concurrently to a finite element model of the periphery. The model, Coarse-Grained Molecular Dynamics (CGMD), builds a generalized finite element formalism from the underlying atomistic physics in order to ensure a smooth coupling between regions governed by different length scales. The result is a model that accurately describes the behavior of the mechanical components of MEMS down to the atomic scale.
Date: December 21, 2001
Creator: Rudd, R E
Object Type: Article
System: The UNT Digital Library
Heats of Formation of Energetic Oxetane Monomers and Polymers (open access)

Heats of Formation of Energetic Oxetane Monomers and Polymers

Energetic oxetane polymers have shown promise as performance-enhancing ingredients in gun and missile propellants. In order to correctly predict the performance of energetic materials containing these polymers, it is important to have accurate, experimentally determined values for the polymer heats of formation ({Delta}H{sub f}). In support of a theoretical study on gun propellant performance, heats of combustion were experimentally determined for a series of oxetane polymers and monomers (see below) using combustion calorimetry, and from these, {Delta}H{sub f} values were calculated. Polymers included BAMO/AMMO, BAMO/NMMO (polyol and TPE), and BNMO/NMMO mixtures. In order to calculate the {Delta}H{sub f} of the polymers from heat of combustion data, a number of assumptions were made regarding the polymer structure and molecular weight. A comparison of the {Delta}H{sub f} values for the monomers and polymers were made, and these values were compared to heats of formation measured elsewhere.
Date: March 21, 2001
Creator: Schmidt, R D & Manser, G E
Object Type: Article
System: The UNT Digital Library
Surface Dynamics during Environmental Degradation of Crystal Surfaces (open access)

Surface Dynamics during Environmental Degradation of Crystal Surfaces

Using in situ optical microscopy and scattering measurements, we have followed the evolution of surface morphology during etching and measured surface etching rates as a function of humidity and undersaturation. From our experiments to date we have developed the following picture of etch pit formation on KDP crystal surfaces. Pit formation is characterized by a nucleation and growth process: the introduction of water creates a condition of undersaturation at the crystal surface. The equilibrium step directions define the orientation of the edges of the pits and the internal surfaces of the pits are low index facets of KDP. For z-cut and type I crystals, the pits are self-similar, indicating their geometry is controlled by equilibrium, not kinetic parameters. For type II crystals, the aspect ratio of the pits can vary dramatically from sample to sample or even within a sample, showing that the kinetics of dissolution can also play a role in determining overall etch pit geometry. The onset of pit formation during exposure to 55% relative humidity (RH) is detectable within a few hours and most of the etching process is complete within 48 hours, but pits continue to grow for a week or longer. At 75% RH, pits …
Date: February 21, 2001
Creator: Whitman, P; DeYoreo, J; Land, T; Miller, E; Suratwala, T; Thorsness, C et al.
Object Type: Report
System: The UNT Digital Library
Test Summary Report INEEL Sodium-Bearing Waste Vitrification Demonstration RSM-01-1 (open access)

Test Summary Report INEEL Sodium-Bearing Waste Vitrification Demonstration RSM-01-1

The U.S. Department of Energy's Idaho National Engineering and Environmental Laboratory is storing large amounts of radioactive and mixed wastes. Most of the sodium-bearing wastes have been calcined, but about a million gallons remain uncalcined, and this waste does not meet current regulatory requirements for long-term storage and/or disposal. As a part of the Settlement Agreement between DOE and the State of Idaho, the tanks currently containing SBW are to be taken out of service by December 31, 2012, which requires removing and treatment the remaining SBW. Vitrification is the option for waste disposal that received the highest weighted score against the criteria used. Beginning in FY 2000, the INEEL high-level waste program embarked on a program for technology demonstration and development that would lead to conceptual design of a vitrification facility in the event that vitrification is the preferred alternative for SBW disposal. The Pacific Northwest National Laborator's Research-Scale Melter was used to conduct these initial melter-flowsheet evaluations. Efforts are underway to reduce the volume of waste vitrified, and during the current test, an overall SBW waste volume-reduction factor of 7.6 was achieved.
Date: May 21, 2001
Creator: Goles, Ronald W.; Perez, Joseph M.; Macisaac, Brett D.; Siemer, Darryl D. & Mccray, John A.
Object Type: Report
System: The UNT Digital Library
X-ray spectroscopy of ion-surface interactions using superconducting tunnel junctions (open access)

X-ray spectroscopy of ion-surface interactions using superconducting tunnel junctions

We have conducted low energy X-ray spectroscopy of ion/surface interactions with superconducting tunnel junction (STJ) detectors. The STJ detectors (Nb-Al-AlOx-Al-Nb) developed at the Lawrence Livermore National Laboratory have a high energy resolution and a high count-rate capability. The detectors are operated in an adiabatic demagnetization refrigerator with 60 mK base temperature at the end of a 40 cm long cold finger, which can be inserted into a UHV sample chamber connected to an ion source. We have studied the interaction of Ar{sup 9+}, O{sup 7+}, N{sup 6+} and C{sup 5+} with various targets (Au, SiH and SiO{sub 2}) at a kinetic energy of 10 keV/q. The resolution of 12-15 eV below 1 keV allows the different satellite lines emitted by these ions to be separated.
Date: July 21, 2001
Creator: Niedermayr, Thomas; Friedrich, Stephan; Cunningham, Mark F.; Frank, Matthias; Briand, Jean-Pierre & Labov, Simon E.
Object Type: Article
System: The UNT Digital Library
Application of the Recent ARF1 Calibration Measurements to the Pbar RF Curve Loading Console Application (P2) (open access)

Application of the Recent ARF1 Calibration Measurements to the Pbar RF Curve Loading Console Application (P2)

The P2 console application (Antiproton Source RF Files) calculates frequency and voltage curves from a sequence of command statements input by the user. P2 initially calculates these curves in terms of the actual frequencies and voltages required on the RF cavity as a function of time. These curves are then converted to the appropriate low-level drive voltages that will cause the RF system high-level electronics to generate the required frequency and voltage ramps. The low-level drive ramps are then downloaded into CAMAC ramp cards. In order to convert the required cavity voltage and frequency into the correct drive voltages P2 uses a set of constants that determined from calibration measurements of the various Antiproton Source RF systems. These constants are editable from the P2 constants window. The P2 constants at the time of this writing are shown in Figure 1. The validity of these constants determines the extent to which P2 able to translate the user's commands into the actual voltages and frequencies that appear on the RF cavity. A comparison of the 4/18/2001 calibration of ARF1 with that presently assumed by P2 shows a large discrepancy in both the frequency constants and the voltage constants. This report documents the …
Date: April 21, 2001
Creator: Werkema, Steve
Object Type: Report
System: The UNT Digital Library
Centrality dependence of multiplicity, transverse energy, and elliptic flow from hydrodynamics (open access)

Centrality dependence of multiplicity, transverse energy, and elliptic flow from hydrodynamics

The centrality dependence of the charged multiplicity, transverse energy, and elliptic flow coefficient is studied in a hydrodynamic model, using a variety of different initializations which model the initial energy or entropy production process as a hard or soft process, respectively. While the charged multiplicity depends strongly on the chosen initialization, the p{sub T}-integrated elliptic flow for charged particles as a function of charged particle multiplicity and the p{sub T}-differential elliptic flow for charged particles in minimum bias events turn out to be almost independent of the initialization.
Date: March 21, 2001
Creator: Kolb, Peter F.; Heinz, Ulrich; Huovinen, Pasi; Eskola, Kari J. & Tuominen, Kimmo
Object Type: Article
System: The UNT Digital Library
Low-Temperature, Anode-Supported High Power Density Solid Oxide Fuel Cells With Nanostructured Electrodes (open access)

Low-Temperature, Anode-Supported High Power Density Solid Oxide Fuel Cells With Nanostructured Electrodes

A simple, approximate analysis of the effect of differing cathode and anode areas on the measurement of cell performance on anode-supported solid oxide fuel cells, wherein the cathode area is smaller than the anode area, is presented. It is shown that the effect of cathode area on cathode polarization, on electrolyte contribution, and on anode resistance, as normalized on the basis of the cathode area, is negligible. There is a small but measurable effect on anode polarization, which results from concentration polarization. Effectively, it is the result of a greater amount of fuel transported to the anode/electrolyte interface in cases wherein the anode area is larger than the cathode area. Experiments were performed on cells made with differing cathode areas and geometries. Cathodic and anodic overpotentials measured using reference electrodes, and the measured ohmic area specific resistances by current interruption, were in good agreement with expectations based on the analysis presented. At 800 C, the maximum power density measured with a cathode area of {approx}1.1 cm{sup 2} was {approx}1.65 W/cm{sup 2} compared to {approx}1.45 W/cm{sup 2} for cathode area of {approx}2 cm{sup 2}, for anode thickness of {approx}1.3 mm, with hydrogen as the fuel and air as the oxidant. At …
Date: June 21, 2001
Creator: Virkar, Anil V.
Object Type: Report
System: The UNT Digital Library
Users guide for SnadiOpt : a package adding automatic differentiation to Snopt. (open access)

Users guide for SnadiOpt : a package adding automatic differentiation to Snopt.

SnadiOpt is a package that supports the use of the automatic differentiation package ADIFOR with the optimization package Snopt. Snopt is a general-purpose system for solving optimization problems with many variables and constraints. It minimizes a linear or nonlinear function subject to bounds on the variables and sparse linear or nonlinear constraints. It is suitable for large-scale linear and quadratic programming and for linearly constrained optimization, as well as for general nonlinear programs. The method used by Snopt requires the first derivatives of the objective and constraint functions to be available. The SnadiOpt package allows users to avoid the time-consuming and error-prone process of evaluating and coding these derivatives. Given Fortran code for evaluating only the values of the objective and constraints, SnadiOpt automatically generates the code for evaluating the derivatives and builds the relevant Snopt input files and sparse data structures.
Date: June 21, 2001
Creator: Gertz, E. M.; Gill, P. E. & Muetherig, J.
Object Type: Report
System: The UNT Digital Library
160 C PROTON EXCHANGE MEMBRANE (PEM) FUEL CELL SYSTEM DEVELOPMENT (open access)

160 C PROTON EXCHANGE MEMBRANE (PEM) FUEL CELL SYSTEM DEVELOPMENT

The objectives of this program were: (a) to develop and demonstrate a new polymer electrolyte membrane fuel cell (PEMFC) system that operates up to 160 C temperatures and at ambient pressures for stationary power applications, and (b) to determine if the GTI-molded composite graphite bipolar separator plate could provide long term operational stability at 160 C or higher. There are many reasons that fuel cell research has been receiving much attention. Fuel cells represent environmentally friendly and efficient sources of electrical power generation that could use a variety of fuel sources. The Gas Technology Institute (GTI), formerly Institute of Gas Technology (IGT), is focused on distributed energy stationary power generation systems. Currently the preferred method for hydrogen production for stationary power systems is conversion of natural gas, which has a vast distribution system in place. However, in the conversion of natural gas into a hydrogen-rich fuel, traces of carbon monoxide are produced. Carbon monoxide present in the fuel gas will in time cumulatively poison, or passivate the active platinum catalysts used in the anodes of PEMFC's operating at temperatures of 60 to 80 C. Various fuel processors have incorporated systems to reduce the carbon monoxide to levels below 10 ppm, …
Date: December 21, 2001
Creator: Marianowski, L. G.
Object Type: Report
System: The UNT Digital Library
Experimental verification of caustic-side solvent extraction for removal of cesium from tank waste. (open access)

Experimental verification of caustic-side solvent extraction for removal of cesium from tank waste.

The objectives of this report are: to demonstrate complete CSSX process flowsheet (proof of concept)--decontamination factor {ge} 40,000, and concentration factor {approx}15; Scientific and technical issues evaluated--stage efficiency, temperature control, hydraulic performance, long time (multi-day) operation, short-term shutdown, effect of solids, and recovery from Cs moving through strip section.
Date: September 21, 2001
Creator: Leonard, R. A.; Aase, S. B.; Arafat, H. A.; Chamberlain, D. B.; Conner, C.; Regalbuto, M. C. et al.
Object Type: Article
System: The UNT Digital Library
Enhancements to modeling regional climate response and global variability (open access)

Enhancements to modeling regional climate response and global variability

Efforts during this grant period focused on three main considerations: (a) developing and testing various climate scenarios with SEAM, a newly created model (b) model reconstruction efforts to speed up computations and (c) optimum realization statistics
Date: December 21, 2001
Creator: Baer, Ferdinand; Tribbia, Joseph J. & Taylor, Mark
Object Type: Report
System: The UNT Digital Library
Precision Measurement of MUON G-2 and Accelerator Related Issues (open access)

Precision Measurement of MUON G-2 and Accelerator Related Issues

A precision measurement of the anomalous g value, a{sub {mu}}=(g-2)/2, for the positive muon has been made using high intensity protons available at the Brookhaven AGS. The result based on the 1999 data a{sub {mu}}=11659202(14)(6) x 10{sup 10} (1.3ppm) is in good agreement with previous measurements and has an error one third that of the combined previous data. The current theoretical value from the standard model is a{sub {mu}} (SM)=11659159.6(6.7) x 10{sup 10} (0.57 ppm) and differ by over 2.5 standard deviation with experiment. Issues with reducing systematic errors and enhancing the injection and storage efficiencies are discussed.
Date: September 21, 2001
Creator: Brown, H. N.; Bunce, G.; Carey, R. M.; Cushman, P.; Danby, G. T.; Debevec, P. T. et al.
Object Type: Article
System: The UNT Digital Library
Approaches to Electric Utility Energy Efficiency for Low Income Customers in a Changing Regulatory Environment (open access)

Approaches to Electric Utility Energy Efficiency for Low Income Customers in a Changing Regulatory Environment

As the electric industry goes through a transformation to a more market-driven model, traditional grounds for utility energy efficiency have come under fire, undermining the existing mechanisms to fund and deliver such services. The challenge, then, is to understand why the electric industry should sustain investments in helping low-income Americans use electricity efficiently, how such investments should be made, and how these policies can become part of the new electric industry structure. This report analyzes the opportunities and barriers to leveraging electric utility energy efficiency assistance to low-income customers during the transition of the electric industry to greater competition.
Date: May 21, 2001
Creator: Brockway, N.
Object Type: Report
System: The UNT Digital Library
Preliminary evaluation of the lifecycle costs and market barriers of reflective pavements (open access)

Preliminary evaluation of the lifecycle costs and market barriers of reflective pavements

The objective of this study is to evaluate the life cycle costs and market barriers associated with using reflective paving materials in streets and parking lots as a way to reduce the urban heat island effect. We calculated and compared the life cycle costs of conventional asphalt concrete (AC) pavements to those of other existing pavement technologies with higher reflectivity-portland cement concrete (PCC), porous pavements, resin pavements, AC pavements using light-colored chip seals, and AC pavements using light-colored asphalt emulsion additives. We found that for streets and parking lots, PCC can provide a cost-effective alternative to conventional AC when severely damaged pavements must be completely reconstructed. We also found that rehabilitating damaged AC streets and intersections with thin overlays of PCC (ultra-thin white topping) can often provide a cost-effective alternative to standard rehabilitation techniques using conventional AC. Chip sealing is a common maintenance treatment for low-volume streets which, when applied using light-colored chips, could provide a reflective pavement surface. If the incremental cost of using light-colored chips is low, this chip sealing method could also be cost-effective, but the incremental costs of light-colored chips are as of yet uncertain and expected to vary. Porous pavements were found to have higher …
Date: November 21, 2001
Creator: Ting, M.; Koomey, J.G. & Pomerantz, M.
Object Type: Report
System: The UNT Digital Library
Explicit Determination of Piezoelectric Eshelby Tensors for a Spheroidal Inclusion (open access)

Explicit Determination of Piezoelectric Eshelby Tensors for a Spheroidal Inclusion

In this paper, by systematically treating the integrals involved in the piezoelectric inclusion problem, explicit results were obtained for the piezoelectric Eshelby tensors for a spheroidal inclusion aligned along the axis of the anisotropy in a transversely isotropic piezoelectric material. This problem was first treated by Dunn and Wienecke (1996) using a Green's function approach, which closely follows Withers' approach (1989) for an ellipsoidal inclusion problem in a transversely isotropic elastic medium. The same problem was recently treated by Michelitsch and Levin (2000) also using a Green's function approach. In this paper, a different method was used to obtain the explicit results for the piezoelectric Eshelby tensors for a spheroidal inclusion. The method is a direct extension of a more unified approach, which has been recently developed by Mikata (2000), which is based on Deeg's results (1980) on a piezoelectric inclusion problem. The main advantage of this method is that it is more straightforward and simpler than Dunn and Wienecke (1996), or Michelitsch and Levin (2000), and the results are a little bit more explicit than their solutions. The key step of this paper is an analytical closed form evaluation of several integrals, which was made possible after a careful …
Date: June 21, 2001
Creator: Mikata, Yozo
Object Type: Report
System: The UNT Digital Library
Effects of composition and exposure on the solar reflectance of Portland cement concrete (open access)

Effects of composition and exposure on the solar reflectance of Portland cement concrete

Increasing the solar reflectance (albedo) of a paved surface keeps it cooler in the sun, reducing convection of heat from pavement to air and thereby decreasing the ambient air temperature. Simulations of the influence of pavement albedo on air temperature in Los Angeles predict that increasing the albedo of 1,250 km2 of pavement by 0.25 would save cooling energy worth $15M yr-1, and reduce smog-related medical and lost-work expenses by $76M yr-1. Most sidewalks and a small fraction of roads and parking areas are paved with portland cement concrete, which can be made quite reflective through suitable choice of cement and aggregate. Variations with composition and environmental exposure of the albedos of portland cement concrete pavements were investigated through laboratory fabrication and exposure of 32 mixes of concrete. Twenty-four mixes yielded substandard, ''rough'' concretes due to high, unmet aggregate water demand. The albedos of the remaining eight ''smooth'' concrete mixes ranged from 0.41 to 0.77 (mean 0.59). Simulated weathering, soiling, and abrasion each reduced average concrete albedo (mean decreases 0.06, 0.05, and 0.19, respectively), though some samples became slightly more reflective through weathering or soiling. Simulated rain (wetting) strongly depressed the albedos of concretes (mean decrease 0.23) until their surfaces …
Date: December 21, 2001
Creator: Levinson, Ronnen & Akbari, Hashem
Object Type: Report
System: The UNT Digital Library
Oak Ridge Multiple Attribute System (ORMAS) for Pu, HEU, HE, Chemical Agents, and Drugs (open access)

Oak Ridge Multiple Attribute System (ORMAS) for Pu, HEU, HE, Chemical Agents, and Drugs

The concept for the Oak Ridge Multiple Attribute System (ORMAS) is a Nuclear Materials Identification System (NMIS) time-dependent coincidence processor that incorporates gamma ray spectrometry and utilizes a small, lightweight, portable DT neutron (14.1 MeV) generator (1 x 10{sup 8} n/s), proton recoil scintillation detectors, and a gamma ray detector (HPGe). ORMAS is based on detecting fission neutrons and gamma rays from inherent source fission, fission induced by the external DT source, gamma ray detection of natural emissions of uranium and Pu, and induced gamma ray emission by the interaction of the 14.1 MeV neutrons from the DT source. This system is uniquely suited for detection of shielded highly enriched uranium (HEU), plutonium and other special nuclear materials, and detection of high explosives (HE), chemical agents, and in some cases, drugs. It could easily be adjusted to utilize a trusted processor that incorporates information barrier and authentication techniques using open software and then be useful in some international applications for materials whose characteristics may be classified. Since it is based entirely on commercially available components, the entire system, including the NMIS data acquisition boards, can be built with commercial off the shelf components (COTS). ORMAS incorporates the PINS technology of …
Date: September 21, 2001
Creator: Mihalczo, J.T.
Object Type: Report
System: The UNT Digital Library
Modeling the acceleration field and objective lens for an aberration corrected photoemission electron microscope (open access)

Modeling the acceleration field and objective lens for an aberration corrected photoemission electron microscope

None
Date: September 21, 2001
Creator: Feng, J.; Padmore, H.; Wei, D.H.; Anders, S.; Wu, Y.; Scholl, A. et al.
Object Type: Article
System: The UNT Digital Library
A Measurement System for Systematic Hydrological Characterization of Unsaturated Fractured Welded Tuff in a Mined Underground Tunnel (open access)

A Measurement System for Systematic Hydrological Characterization of Unsaturated Fractured Welded Tuff in a Mined Underground Tunnel

A field investigation of unsaturated flow through a lithophysal unit of fractured welded tuff containing lithophysal cavities has been initiated. To characterize flow in this spatially heterogeneous medium, a systematic approach has been developed to perform tests in boreholes drilled at regular intervals in an underground tunnel (drift). In this paper, we describe the test equipment system that has been built for this purpose. Since the field-scale measurements, of liquid flow in the unsaturated, fractured rocks, require continuous testing for periods of days to weeks, the control of test equipment has been fully automated, allowing operation with no human presence at the field site. Preliminary results from the first set of tests are described. These tests give insight into the role of the matrix (perhaps also lithophysal cavities) as potential storage during the initial transient flow prior to the breakthrough of water at the drift crown, as well as the role of connected fractures that provide the subsequent quasi-steady flow. These tests also reveal the impact of evaporation on seepage into the drift.
Date: November 21, 2001
Creator: Cook, P. J.; Salve, R.; Freifeld, B. M. & Tsang, Y. W.
Object Type: Report
System: The UNT Digital Library
Supporting Rock Fall Calculation for Drift Degradation: Quantification of Uncertainties (open access)

Supporting Rock Fall Calculation for Drift Degradation: Quantification of Uncertainties

The purpose of this calculation is to quantify previously unquantified uncertainties associated with the Drift Degradation Analysis (BSC 2001b). The results from this calculation will support the development of a technical report to document supplemental science and performance analyses. This calculation has been developed according to the guidance provided by the ''Technical Work Plan for EBS Department Modeling FY 01 Work Activities'' (BSC 2001a). The specific objective of this calculation is to perform sensitivity studies to assess the impact of the following parameters on rock fall results: (1) parameter M, a multiplier of fracture trace lengths sampled from field data; (2) Terzaghi correction factor for subhorizontal fractures; and (3) number of Monte Carlo simulations. The scope of this calculation includes using the fracture data inputs from the ''Drift Degradation Analysis'' (BSC 2001b) as input to the Discrete Region Key Block Analysis (DRKBA) numerical code. Outputs from this program includes the expected quantities and size distributions of failed rock blocks. This calculation is applicable to unsupported drifts without backfill. This calculation is associated with the engineering and performance analysis activities of the Engineered Barrier System Department, and was developed in accordance with AP-3.12Q, ''Calculations''.
Date: November 21, 2001
Creator: Lin, M. & Kicker, D. C.
Object Type: Report
System: The UNT Digital Library