Influence of Clastic Dikes on Vertical Migration of Contaminants in the Vadose Zone at Hanford (open access)

Influence of Clastic Dikes on Vertical Migration of Contaminants in the Vadose Zone at Hanford

The purpose of this study was to examine the hypothesis that clastic dikes could form a preferential flow path through the vadose zone to the water table at the Hanford Site. Clastic dikes are subvertical structures that form within sedimentary sequences after deposition, and cut across the original sedimentary layers. They are common throughout the Hanford Site, often occurring in organized polygonal networks. In the initial phase of the project, we analyzed the large-scale geometry of the clastic dikes and developed an algorithm for simulating their spatial distribution. This result will be useful in providing maps of the potential distribution of clastic dikes in areas where they are not exposed at the surface (e.g., where covered by windblown sand or by construction of facilities like tank farms at the surface). In addition to the study of the large scale distribution of the dikes, a major focus of the project was on field, laboratory, and modeling studies of the hydrogeologic al properties of the clastic dikes and the effect that they have on transport of water through the vadose zone. These studies were performed at two field locations at the Hanford Site. We performed an extensive series of field and laboratory …
Date: March 14, 2003
Creator: Murray, Christopher J.; Ward, Anderson L. & Wilson, John L.
Object Type: Report
System: The UNT Digital Library
Updated Volumetric Expansion Factors for K Basin Sludge During Storage (open access)

Updated Volumetric Expansion Factors for K Basin Sludge During Storage

Sludge has accumulated in the K East (KE) and K West (KW) Basins at the Hanford Site. This sludge contains metallic uranium and uranium oxides that will corrode, hydrate, and generate and consume gases during containerized storage. From these corrosion reactions, two sludge expansion mechanisms can be expected: 1) expansion of the volume of the sludge solids from the generation of corrosion oxidation products that occupy more space than the starting-state sludge; and 2) expansion of the bulk sludge volume from the retention of hydrogen gas bubbles. This report provides a review and updated projections of the volumetric expansion occurring due to corrosion and gas retention during the containerized storage of K Basin sludge. New design and safety basis volume expansion values are provided for the following sludge streams: KW Floor, KW North Loadout Pit, KW canister, and fuel piece sludge.
Date: March 14, 2003
Creator: Schmidt, Andrew J. (BATTELLE (PACIFIC NW LAB)) & Delegard, Calvin H. (BATTELLE (PACIFIC NW LAB))
Object Type: Report
System: The UNT Digital Library
Nuclear structure with accurate chiral perturbation theory nucleon-nucleon potential: Application to 6Li and 10B (open access)

Nuclear structure with accurate chiral perturbation theory nucleon-nucleon potential: Application to 6Li and 10B

The authors calculate properties of A = 6 system using the accurate charge-dependent nucleon-nucleon (NN) potential at fourth order of chiral perturbation theory. By application of the ab initio no-core shell model (NCSM) and a variational calculation in the harmonic oscillator basis with basis size up to 16 {h_bar}{Omega} they obtain the {sup 6}Li binding energy of 28.5(5) MeV and a converged excitation spectrum. Also, they calculate properties of {sup 10}B using the same NN potential in a basis space of up to 8 {h_bar}{Omega}. The results are consistent with results obtained by standard accurate NN potentials and demonstrate a deficiency of Hamiltonians consisting of only two-body terms. At this order of chiral perturbation theory three-body terms appear. It is expected that inclusion of such terms in the Hamiltonian will improve agreement with experiment.
Date: October 14, 2003
Creator: Navratil, P & Caurier, E
Object Type: Report
System: The UNT Digital Library
Investigation into the Role of Initial Conditions on Rayleigh-Taylor Instabilities by Low Atwood Experiments and Simulations (open access)

Investigation into the Role of Initial Conditions on Rayleigh-Taylor Instabilities by Low Atwood Experiments and Simulations

The primary goal of the research being conducted this summer is to investigate the role of initial conditions in the development of a two fluid mix driven by Rayleigh-Taylor instability. The effects of initial conditions will be studied through the use of experimental facilities located at the Buoyancy-Driven Mixing Lab at Texas A&M University and through high resolution direct numerical simulations of the experiment by the MIRANDA code developed at Lawrence Livermore National Lab. The Experimental Objectives are: (1) Analyze the early time development of a two fluid Rayleigh-Taylor driven mix between two miscible fluids at low Atwood numbers. (2) Quantify the initial conditions of the unstably stratified fluids by means of statistical mixing parameters and spectral analysis of the centerline density fluctuations. (3) Capture PLIF images of initial development of the flow for use in simulation setup. (Wayne Kraft) (4) Determine exactly what component of the experimental mixing data (position downstream from the splitter plate) most accurately represents the initial conditions of the experiment. The Simulation Objectives are: (1) Perform two dimensional and three dimensional simulations of the experimental setup. Analyze the results of these simulations for comparison to the experimental results. (2) Various methods of implementing the initial …
Date: July 14, 2003
Creator: Mueschke, N; Andrews, M & Schilling, O
Object Type: Report
System: The UNT Digital Library
Simulations of rapid pressure-induced solidification in molten metals (open access)

Simulations of rapid pressure-induced solidification in molten metals

The process of interest in this study is the solidification of a molten metal subjected to rapid pressurization. Most details about solidification occurring when the liquid-solid coexistence line is suddenly transversed along the pressure axis remain unknown. We present preliminary results from an ongoing study of this process for both simple models of metals (Cu) and more sophisticated material models (MGPT potentials for Ta). Atomistic (molecular dynamics) simulations are used to extract details such as the time and length scales that govern these processes. Starting with relatively simple potential models, we demonstrate how molecular dynamics can be used to study solidification. Local and global order parameters that aid in characterizing the phase have been identified, and the dependence of the solidification time on the phase space distance between the final (P,T) state and the coexistence line has been characterized.
Date: October 14, 2003
Creator: Patel, M V & Streitz, F H
Object Type: Article
System: The UNT Digital Library
General Constraints on Cross Sections Deduced from Surrogate Reactions (open access)

General Constraints on Cross Sections Deduced from Surrogate Reactions

Cross sections that cannot be measured in the laboratory, e.g. because the target lifetime is too short, can be inferred indirectly from a different reaction forming the same compound system, but with a more accessible beam/target combination (the ''surrogate-reaction'' technique). The reactions share the same compound system and a common decay mechanism, but they involve different formation processes. Therefore, an implicit constraint is imposed on the inferred cross section deduced from the measured surrogate-reaction data, through the common decay mechanism. In this paper, the mathematical consequences of this implicit constraint are investigated. General formulas are derived from upper and lower bounds on the inferred cross section, estimated from surrogate data in a procedure which does not require any modeling of the common decay process. As an example, the formulas developed here are applied to the case of the {sup 235}U(n,f) cross section, deduced from {sup 234}U(t,pf) surrogate data. The calculated bounds are not very tight in this particular case. However, by introducing a few qualitative assumptions about the physics of the fission process, meaningful bounds on the deduced cross section are obtained. Upper and lower limits for the cross-section ratio of the (n,f) reaction on the {sup 235}U isomer at …
Date: August 14, 2003
Creator: Younes, W.
Object Type: Report
System: The UNT Digital Library
Comparison of Experimental and Model Data for the Evaporation of a Synthetic Topopah Spring Tuff Pore Water, Yucca Mountain, NV (open access)

Comparison of Experimental and Model Data for the Evaporation of a Synthetic Topopah Spring Tuff Pore Water, Yucca Mountain, NV

The evaporation of a range of synthetic pore water solutions representative of the potential high-level-nuclear-waste repository at Yucca Mountain, NV is being investigated. The motivation of this work is to understand and predict the range of brine compositions that may contact the waste containers from evaporation of pore waters, because these brines could form corrosive thin films on the containers and impact their long-term integrity. A relatively complex synthetic Topopah Spring Tuff pore water was progressively concentrated by evaporation in a closed vessel, heated to 95 C in a series of sequential experiments. Periodic samples of the evaporating solution were taken to determine the evolving water chemistry. According to chemical divide theory at 25 C and 95 C our starting solution should evolve towards a high pH carbonate brine. Results at 95 C show that this solution evolves towards a complex brine that contains about 99 mol% Na{sup +} for the cations, and 71 mol% Cl{sup -}, 18 mol% {Sigma}CO{sub 2}(aq), 9 mol% SO{sub 4}{sup 2-} for the anions. Initial modeling of the evaporating solution indicates precipitation of aragonite, halite, silica, sulfate and fluoride phases. The experiments have been used to benchmark the use of the EQ3/6 geochemical code in …
Date: October 14, 2003
Creator: Alai, M; Sutton, M & Carroll, S
Object Type: Article
System: The UNT Digital Library
Observation of anomalous Iron Ion Charge Distribution in FTU (open access)

Observation of anomalous Iron Ion Charge Distribution in FTU

Iron coming from the poloidal limiter or the stainless steel vessel is an important intrinsic impurity in the FTU tokamak discharges, and X-ray and VUV spectroscopy provide useful information about the impurity behavior. The iron ion charge state distribution, as usual for tokamaks, is analyzed assuming a collisional radiative model and an anomalous perpendicular diffusion. In our experiment the iron ionization level depends, as it is expected, on central electron temperature (fig. 1), but the ion charge state distribution shows a different behavior when the first wall material or the iron source are changed.
Date: November 14, 2003
Creator: Finkenthal, M.; May, M.; Pacella, D.; Leigheb, M.; Zagorski, R.; Mattioli, M. et al.
Object Type: Article
System: The UNT Digital Library
The Interaction of Dislocations and Radiation-Induced Obstacles at High-Strain Rate (open access)

The Interaction of Dislocations and Radiation-Induced Obstacles at High-Strain Rate

Improved understanding of the plastic deformation of metals during high strain rate shock loading is key to predicting their resulting material properties. This paper presents the results of molecular dynamics simulations that identify the deformation modes of aluminum over a range of applied shear stresses and examines the interaction between dislocations and irradiation induced obstacles. These simulations show that while super-sonic dislocation motion can occur during impact loading, the finite dimensions of the materials render this motion transient. Larger applied loads do not stabilize supersonic dislocations, but instead lead an alternate deformation mode, namely twinning. Finally, the atomistic mechanisms that underlie the observed changes in the mechanical properties of metals as a function of irradiation are examined. Specifically, simulations of the interactions between moving edge dislocations and nanometer-sized helium bubbles provide insight into increases of the critical shear stresses but also reveal the effect of internal gas pressure on the deformation mode. The information gained in these studies provides fundamental insight into materials behavior, as well as important inputs for multi-scale models of materials deformation.
Date: July 14, 2003
Creator: Young, J. A.; Wirth, B. D.; Robach, J. & Robertson, I.
Object Type: Article
System: The UNT Digital Library
An Ecosystem-Based Restoration Plan with Emphasis on Salmonid Habitats in the Lower Columbia River and Estuary (open access)

An Ecosystem-Based Restoration Plan with Emphasis on Salmonid Habitats in the Lower Columbia River and Estuary

The Bonneville Power Administration (BPA), in coordination with the U. S. Army Corps of Engineers (COE) and NOAA Fisheries, originated this project (BPA Project No. 2002-076; Contract No. DE-AC06-76RL01830, Release No. 652-24). Their intent was to develop a useful habitat restoration plan for the lower Columbia River and estuary to help guide restoration efforts and fulfill Reasonable and Prudent Alternative Action 159 of the 2000 National Marine Fisheries Service Biological Opinion on operation of the Federal Columbia River Power System. This document focuses on salmon habitat, although its ecosystem-based approach necessarily affects other species as well. Salmon habitat restoration is best undertaken within the context of other biota and physical processes using an ecosystem perspective. The anticipated audience for the plan includes entities responsible for, interested in, or affected by habitat restoration in the lower Columbia River and estuary. Timeframes to apply this plan extend from the immediate (2003-2004) to the near-term (2005-2006) to the long-term (2007 and beyond). We anticipate and encourage that the plan be revised as new knowledge and experience are attained. A team comprised of the Columbia River Estuary Study Taskforce (CREST), the Lower Columbia River Estuary Partnership (Estuary Partnership), and Pacific Northwest National Laboratory (PNNL) …
Date: October 14, 2003
Creator: Johnson, Gary E.; Thom, Ronald M.; Whiting, Allan H.; Sutherland, George B.; Berquam, Taunja J.; Ebberts, Blaine et al.
Object Type: Report
System: The UNT Digital Library
Ab initio shell model with a chiral-symmetry-based three-nucleon force for the p-shell nuclei (open access)

Ab initio shell model with a chiral-symmetry-based three-nucleon force for the p-shell nuclei

The ab initio no-core shell model (NCSM) is extended to include a realistic three-body interaction in calculations for p-shell nuclei. They present results of first applications using the Argonne V8' nucleon-nucleon (NN) potential and the Tucson-Melbourne TM'(99) three-nucleon interaction (TNI). In addition to increase of binding energy, they observe a trend toward level-ordering and level-spacing improvement in comparison to experiment. With the TNI they obtain a correct ground-state spin for {sup 10}B contrary to calculations with NN potentials only. They also investigate neutrino-{sup 12}C exclusive cross sections and muon capture on {sup 12}C. They show that realistic nucleon-nucleon interactions underpredict the experimental cross sections by a factor of two or more. By including the TNI a much better agreement with experiment is achieved along with an encouraging trend.
Date: October 14, 2003
Creator: Navratil, P; Hayes, A C; Vary, J P & Ormand, W E
Object Type: Report
System: The UNT Digital Library
Radiocarbon in otoliths of yelloweye rockfish (Sebastes ruberrimus): a reference time series for the coastal waters of southeast Alaska (open access)

Radiocarbon in otoliths of yelloweye rockfish (Sebastes ruberrimus): a reference time series for the coastal waters of southeast Alaska

Atmospheric testing of thermonuclear devices during the 1950s and 1960s created a global radiocarbon ({sup 14}C) signal in the environment that has provided a useful tracer and chronological marker in oceanic systems and organisms. The bomb-generated {sup 14}C signal retained in fish otoliths can be used as a permanent, time-specific recorder of the 14C present in ambient seawater, making it a useful tool in age validation of fishes. The goal of this study was to determine {sup 14}C levels in otoliths of the age-validated yelloweye rockfish (Sebastes ruberrimus) to establish a reference time series for the coastal waters of southeast Alaska. Radiocarbon values from the first year's growth of 43 yelloweye rockfish otoliths were plotted against estimated birth year to produce a 14C time series for these waters spanning 1940 to 1990. The time series shows the initial rise of bomb 14C occurred in 1958 in coastal southeast Alaskan waters and {sup 14}C levels rose relatively rapidly to peak {Delta}{sup 14}C values (60-70%) between 1966 and 1971, with a subsequent declining trend through the end of the record in 1990 (-3.2%). In addition, the radiocarbon data, independent of the radiometric study, confirms the longevity of the yelloweye rockfish up to …
Date: October 14, 2003
Creator: Kerr-Ferrey, L A; Andrews, A H; Frantz, B R; Coale, K H; Brown, T A & Cailliet, G M
Object Type: Article
System: The UNT Digital Library
EXISTENCE OF SUPERSCRIPT 4 SUBSCRIPT LAMBDA SUBSCRIPT LAMBDA H AND DECAY TO A RESONANCE IN SUPERSCRIPT 4 LAMBDA. (open access)

EXISTENCE OF SUPERSCRIPT 4 SUBSCRIPT LAMBDA SUBSCRIPT LAMBDA H AND DECAY TO A RESONANCE IN SUPERSCRIPT 4 LAMBDA.

Experiment E906 at the BNL-AGS, searching for light S = -2 hypernuclei, found strong evidence for the nuclide {sub {Lambda}{Lambda}}{sup 4}H. Perhaps the most striking feature of this experiment was the presence in the data of a narrow low-momentum {pi}{sup -} line at k{sub {pi}} = 104-105 MeV/c. This line was ascribed to the decay of {sub {Lambda}{Lambda}}{sup 4}H into a resonant state in {sub {Lambda}}{sup 4}H. The existence of such a state is shown to be plausible, its characteristics delineated, and its relevance to ongoing theoretical calculations considered.
Date: October 14, 2003
Creator: KAHANA,S. H. MILLENER,D. J.
Object Type: Article
System: The UNT Digital Library
Hanford Site Environmental Surveillance Master Sampling Schedule for Calendar Year 2003 (open access)

Hanford Site Environmental Surveillance Master Sampling Schedule for Calendar Year 2003

Environmental Surveillance of the Hanford Site and surrounding areas is conducted by the Pacific Northwest National Laboratory (PNNL) for the U.S. Department of Energy (DOE). Document contains CY03 schedules for the routine collection of samples for the Surface Environmental Surveillance Project (SESP) and Drinking Water Monitoring Project.
Date: February 14, 2003
Creator: Bisping, Lynn E.
Object Type: Report
System: The UNT Digital Library
Diffusion and multiple anisotropic scattering for global illumination in clouds (open access)

Diffusion and multiple anisotropic scattering for global illumination in clouds

The diffusion method is a good approximation inside the dense core of a cloud, but not at the more tenuous boundary regions. Also, it breaks down in regions where the density of scattering droplets is zero. We have enhanced it by using hardware cell projection volume rendering at cloud border voxels to account for the straight line light transport across these empty regions. We have also used this hardware volume rendering at key voxels in the low-density boundary regions to account for the multiple anisotropic scattering of the environment.
Date: October 14, 2003
Creator: Max, N L; Schussman, G; Miyazaki, R; Iwasaki, K & Nishita, T
Object Type: Article
System: The UNT Digital Library
Torsional Buckling and Writhing Dynamics of Elastic Cables and DNA (open access)

Torsional Buckling and Writhing Dynamics of Elastic Cables and DNA

Marine cables under low tension and torsion on the sea floor can undergo a dynamic buckling process during which torsional strain energy is converted to bending strain energy. The resulting three-dimensional cable geometries can be highly contorted and include loops and tangles. Similar geometries are known to exist for supercoiled DNA and these also arise from the conversion of torsional strain energy to bending strain energy or, kinematically, a conversion of twist to writhe. A dynamic form of Kirchhoff rod theory is presented herein that captures these nonlinear dynamic processes. The resulting theory is discretized using the generalized-method for finite differencing in both space and time. The important kinematics of cross-section rotation are described using an incremental rotation ''vector'' as opposed to traditional Euler angles or Euler parameters. Numerical solutions are presented for an example system of a cable subjected to increasing twist at one end. The solutions show the dynamic evolution of the cable from an initially straight element, through a buckled element in the approximate form of a helix, and through the dynamic collapse of this helix through a looped form.
Date: February 14, 2003
Creator: Goyal, S; Perkins, N C & Lee, C L
Object Type: Article
System: The UNT Digital Library
Progress Report on the Advanced Large-Area Plastic Scintillators (ALPS) Project (open access)

Progress Report on the Advanced Large-Area Plastic Scintillators (ALPS) Project

The U.S. Department of Energy tasked Pacific Northwest National Laboratory to investigate possible technological avenues for substantially advancing the state-of-the-art in gamma detection via large-area plastic scintillators. This letter report describes progress to date on this project. Early phases of the project, which commenced in January 2003, have focused on (1) quantifying the light-collection efficiency in plastic scintillator sheets as a function of photomultiplier tube positioning and edge-area coverage, (2) developing a conceptual design for a demonstration sensor, and (3) conducting initial laboratory setup and preliminary experiments using relatively small plastic scintillators for readout technique development and benchmarking of the modeling studies.
Date: May 14, 2003
Creator: Jordan, David V.; Geelhood, Bruce D.; Reeder, Paul L.; Stephens, Daniel L.; Craig, Richard A. & McIntyre, Justin I.
Object Type: Report
System: The UNT Digital Library
Modeling Fluid Flow and Electrical Resistivity in Fractured Geothermal Reservoir Rocks (open access)

Modeling Fluid Flow and Electrical Resistivity in Fractured Geothermal Reservoir Rocks

Phase change of pore fluid (boiling/condensing) in rock cores under conditions representative of geothermal reservoirs results in alterations of the electrical resistivity of the samples. In fractured samples, phase change can result in resistivity changes that are more than an order of magnitude greater than those measured in intact samples. These results suggest that electrical resistivity monitoring may provide a useful tool for monitoring the movement of water and steam within fractured geothermal reservoirs. We measured the electrical resistivity of cores of welded tuff containing fractures of various geometries to investigate the resistivity contrast caused by active boiling and to determine the effects of variable fracture dimensions and surface area on water extraction. We then used the Nonisothermal Unsaturated Flow and Transport model (NUFT) (Nitao, 1998) to simulate the propagation of boiling fronts through the samples. The simulated saturation profiles combined with previously reported measurements of resistivity-saturation curves allow us to estimate the evolution of the sample resistivity as the boiling front propagates into the rock matrix. These simulations provide qualitative agreement with experimental measurements suggesting that our modeling approach may be used to estimate resistivity changes induced by boiling in more complex systems.
Date: January 14, 2003
Creator: Detwiler, R. L.; Roberts, J. J.; Ralph, W. & Bonner, B. P.
Object Type: Article
System: The UNT Digital Library
Susceptibility of Welded and Non-Welded Titanium Alloys to Environmentally Assisted Cracking in Simulated Concentrated Ground Waters (open access)

Susceptibility of Welded and Non-Welded Titanium Alloys to Environmentally Assisted Cracking in Simulated Concentrated Ground Waters

The engineering barriers for the nuclear waste repository at Yucca Mountain include a double walled container and a detached drip shield. The material selected to construct the drip shield will be Titanium Grade 7 (Ti Gr 7 or R52400). Ti Gr 7 is highly resistant to corrosion and consequently it is widely used to handle aggressive industrial environments. The model for the degradation of the engineering barriers includes three modes of corrosion, namely general corrosion, localized corrosion and environmentally assisted cracking (EAC). The objective of the current research was to characterize the susceptibility of three titanium alloys to EAC in several environmental conditions with varying solution composition, pH and temperature. The susceptibility to EAC was evaluated using constant deformation (deflection) U-bend specimens in both the non-welded and welded conditions. Results show that after more than five years exposure in the vapor and liquid phases of alkaline (pH {approx} 10) and acidic (pH {approx} 3) multi-ionic environments at 60 C and 90 C, most of the specimens were free from EAC. The only specimens that suffered EAC were welded Ti Gr 12 (R53400) exposed to liquid simulated concentrated water (SCW) at 90 C.
Date: October 14, 2003
Creator: Fix, D. V.; Estill, J. C.; Wong, L. L. & Rebak, R. B.
Object Type: Article
System: The UNT Digital Library
ITER Model Coil Tests Overview: Nb3Sn Strand Properties in Cable-in-Conduit-Conductors (open access)

ITER Model Coil Tests Overview: Nb3Sn Strand Properties in Cable-in-Conduit-Conductors

During the ITER Model Coil Program two large coils and three Insert coils were built and tested. The test campaigns provided very valuable data on the Conductor in Conduit Cable (CICC) properties. The tests showed that the Nb3Sn strands in CICC behave differently than so-called witness strands, which underwent the same heat treatment. The paper describes Volt-temperature characteristics (VTC) and Volt-Ampere characteristics (VAC) measured in the tests, presents comparisons with the witness strands, and interprets the test results.
Date: April 14, 2003
Creator: Martovetsky, N. N.
Object Type: Article
System: The UNT Digital Library
Level II Milestone Review of LLNL Program on Grain-Scale Dynamics in Explosives (open access)

Level II Milestone Review of LLNL Program on Grain-Scale Dynamics in Explosives

This document describes an evaluation of the Level II Milestone achievements of the LLNL program on Grain-Scale Dynamics in Explosives on January 14, 2003. ''The Grain-Scale Dynamics in Explosives Program'' is a mixture of advanced computational methodology and physico-chemical theory applied to understanding deflagration and detonation of plastic-bonded explosives from the nano to the macro scales. At many points, the modeling is tied directly to experiments within the precisions of both. Advances are needed in the experimental, theoretical, and computational aspects of detonations. Work reported in this review represents significant, cross-pollinating advances in each area. The team successfully carried out ALE-3D simulations of deflagration in PBX with grain scale effects. (Milestone requirements 1 and 2), interpreted experimental data on flame speed vs. pressure and sensitivity to global kinetics in terms of ALE-3D simulations (Milestone requirement 3), and used the results of these simulations to develop a continuum reactive flow model that captures some of these effects (Milestone requirement 4). By comparing experiments and detonation velocities in small diameter, unconfined explosives, they found non-idealities that remain at intermediate diameters (ca. 1.5 mm) that require further analysis. In all of these areas, the project team has met, indeed exceeded, their Level II …
Date: January 14, 2003
Creator: Nicol, M F; Benson, D J & Yip, S
Object Type: Report
System: The UNT Digital Library
Quantifying Flaw Characteristics from IR NDE Data (open access)

Quantifying Flaw Characteristics from IR NDE Data

Work is presented which allows flaw characteristics to be quantified from the transient IR NDE signature. The goal of this effort was to accurately determine the type, size and depth of flaws revealed with IR NDE, using sonic IR as the example IR NDE technique. Typically an IR NDE experiment will result in a positive qualitative indication of a flaw such as a cold or hot spot in the image, but will not provide quantitative data thereby leaving the practitioner to make educated guesses as to the source of the signal. The technique presented here relies on comparing the transient IR signature to exact heat transfer analytical results for prototypical flaws, using the flaw characteristics as unknown fitting parameters. A nonlinear least squares algorithm is used to evaluate the fitting parameters, which then provide a direct measure of the flaw characteristics that can be mapped to the imaged surface for visual reference. The method uses temperature data for the heat transfer analysis, so radiometric calibration of the IR signal is required. The method provides quantitative data with a single thermal event (e.g. acoustic pulse or flash), as compared to phase-lock techniques that require many events. The work has been tested …
Date: February 14, 2003
Creator: Miller, W; Philips, N R; Burke, M W & Robbins, C L
Object Type: Article
System: The UNT Digital Library
A Comparison of the Effect of Temperature on the Passivity Breakdown and Repassivation Potentials of Wrought and Welded Alloy 22 in 5 M CAC12 (open access)

A Comparison of the Effect of Temperature on the Passivity Breakdown and Repassivation Potentials of Wrought and Welded Alloy 22 in 5 M CAC12

The study of the electrochemical behavior of wrought and welded Alloy 22 was carried out in 5 M CaC12 at various temperatures. Comparisons were made between the electrochemical behaviors of the wrought and welded forms of Alloy 22 Multiple Crevice Assembly (MCA) specimens. The susceptibility to corrosion was found to increase with increase in temperature in both the wrought and the welded forms of the alloy: Nevertheless, the measure critical breakdown potential E{sub crit} was found to be Similar for the wrought and welded specimens.
Date: February 14, 2003
Creator: Ilevbare, G
Object Type: Article
System: The UNT Digital Library
Hypernuclear Structure From Gamma-Ray Spectroscopy. (open access)

Hypernuclear Structure From Gamma-Ray Spectroscopy.

The energies of p-shell hypernuclear {gamma} rays obtained from recent experiments using the Hyperball at BNL and KEK are used to constrain the YN interaction which enters into shell-model calculations which include both {Lambda} and {Sigma} configurations.
Date: October 14, 2003
Creator: Millener, D. J.
Object Type: Article
System: The UNT Digital Library