EFFECTS OF MINERALOGY, GRAIN SIZE, AND SOLUTION COMPOSITION ON LITHIUM SORPTION TO SATURATED ALLUVIUM SOUTH OF YUCCA MOUNTAIN, NEVADA (open access)

EFFECTS OF MINERALOGY, GRAIN SIZE, AND SOLUTION COMPOSITION ON LITHIUM SORPTION TO SATURATED ALLUVIUM SOUTH OF YUCCA MOUNTAIN, NEVADA

Lithium is used frequently as a surrogate for cationic radionuclides such as NpO{sub 2}{sup +} in field and laboratory settings. Current plans include the use of Li{sup +} as a reactive tracer in field tracer testing in the saturated alluvium south of Yucca Mountain, NV, site of a potential high-level nuclear waste. Characterization of the alluvial material for grain size, mineralogy, cation exchange capacity (CEC), and surface area yields data that is compared with lithium batch sorption as a first step in inferring radionuclide transport behavior. This research will be used to help assess performance of the potential repository.
Date: May 1, 2001
Creator: Sullivan, E. J.; Reimus, P. W. & Ding, M.
System: The UNT Digital Library
A Tritiated-Water Detector with U-232/Th-228 Source (open access)

A Tritiated-Water Detector with U-232/Th-228 Source

The detection capabilities of the new U-232/Th-228 source are comparable to those of the Na-24 source. The main benefit in using the new source is the ease of operation. Elimination of the neutron activation step required for Na-24 sources saves about 24 hours in planning, scheduling, and executing. With the new U-232/Th-228 source, the monitor can be put in operation in less than 15 minutes. The long half-life of the U-232/Th-228 source also eliminates the need to record calibration and measurement times, as required for decay corrections when using a Na-24 source.
Date: May 29, 2001
Creator: Baumann, N.P.
System: The UNT Digital Library
FULLY KINETIC SIMULATIONS OF SLOW-MODE SHOCKS (open access)

FULLY KINETIC SIMULATIONS OF SLOW-MODE SHOCKS

Much of the theoretical understanding concerning the structure and essential properties of the slow-mode shock has been obtained from extensive hybrid calculations in which a full kinetic description is retained for the ions while the electrons are approximated as a massless adiabatic fluid. Due to the relatively broad spatial and relatively slow temporal scales of the slow shock, one would expect this approximation to be well justified. However, implicit simulations with kinetic electrons have produced significant differences in comparison to standard hybrid results. In this work, we re-examine the importance of electron dynamics to the slow shock using one-dimensional fully kinetic simulations. We employ a simple explicit simulation technique and fully resolve all relevant spatial and temporal electron scales. The resulting shock structure and ion heating are in excellent agreement with hybrid simulations, indicating the total dissipation arising from kinetic electrons is relatively minor. However, the electron heating is somewhat larger than the corresponding hybrid simulation and clear non-Maxwellian features are observed. In the upstream region, back streaming electrons give rise to double peaked distributions while in the downstream region bi-Maxwellian distributions are observed with T{sub e{parallel}} > T{sub e{perpendicular}}.
Date: May 2001
Creator: Daughton, W.; Winske, D. & Yin, L.
System: The UNT Digital Library
The structural basis of damaged DNA recognition and endonucleolytic cleavage for Very Short Patch Repair endonuclease (open access)

The structural basis of damaged DNA recognition and endonucleolytic cleavage for Very Short Patch Repair endonuclease

None
Date: May 2, 2001
Creator: Tsutakawa, Susan E. & Morikawa, Kosuke
System: The UNT Digital Library
A Simple, Inexpensive in Situ Method for Assessing Acute Toxicity of Effluents to Fish (open access)

A Simple, Inexpensive in Situ Method for Assessing Acute Toxicity of Effluents to Fish

Test chambers for conducting in situ fish bioassays were constructed from 8L polyethylene bottles. Yearling fathead minnows (Pimephales promelas) and young-of-the-year bluegill (Lepomis macrochirus) demonstrated greater than 50 percent survival in the chambers after 65 days of exposure in a reservoir, river, and creek. Fathead minnow survival was substantially greater than that of bluegills. The chambers provide a simple, inexpensive, sensitive technique to screen effluents for toxicity.
Date: May 29, 2001
Creator: Wilde, E.W.
System: The UNT Digital Library
SOME CHEMICAL SAFETY ASPECTS AT LANL (open access)

SOME CHEMICAL SAFETY ASPECTS AT LANL

Recently, the Department of Energy (DOE) and its contractors have begun activities to improve the quality and consistency of chemical safety programs throughout the DOE Complex. Several working groups have been formed to assemble a framework for systematically identifying and quantifying chemical hazards and managing chemical risks. At LANL, chemical safety program is implemented through Laboratory Implementation Requirements (LIRs), which are part of the Integrated Safety Management (ISM) plan that includes Safe Work Practices, emphasizing five core functions; define work, identify and analyze hazards, develop and implement controls, perform work safely, and ensure performance. Work is authorized in medium, low and minimal risk areas and not in high risk. Some chemical safety aspects are discussed in terms of chemical hazards and identification, screening, facility hazard categorization--Category A (high), Category B (moderate), and Category C (low), and their requirements in format and content in Authorization Safety Basis documents.
Date: May 1, 2001
Creator: LAUL, J.
System: The UNT Digital Library
A NEW INTERPHASE FORCE IN TWO-PHASE FLUIDIZED BEDS (open access)

A NEW INTERPHASE FORCE IN TWO-PHASE FLUIDIZED BEDS

Mesoscale structures such as particle clusters have been observed both in experiments and in numerical simulations of circulating fluidized beds. In a numerical simulation, in order to account for the effects of such mesoscale structures, the computational grids have to be fine enough. The use of such fine grids is impractical in engineering applications due to excessive computational costs. To predict the macroscopic behavior of a fluidized bed with reasonable computation cost, they perform a second average over the averaged equations for two-phase flows. A mesoscale inter-phase exchange force is found to be the correlation of the particle volume fraction and the pressure gradient. This force is related to the mesoscale added mass of the two-phase flow. Typically, added mass for particle scale interactions is negligible in gas-solid flows since the gas density is small compared to density of solid particles. However, for a mesoscale structure, such as a bubble, the surrounding media is the mixture of gas and particles. The surrounding fluid density experienced by the mesoscale structure is the density of the surrounding mixture. Therefore, the added mass of a mesoscale structure, such as bubbles, cannot be neglected. The property of this new force is studied based on …
Date: May 1, 2001
Creator: ZHANG, D. & VANDERHEYDEN, W.
System: The UNT Digital Library
UNCERTAINTY, VALIDATION OF COMPUTER MODELS AND THE MYTH OF NUMERICAL PREDICTABILITY (open access)

UNCERTAINTY, VALIDATION OF COMPUTER MODELS AND THE MYTH OF NUMERICAL PREDICTABILITY

None
Date: May 1, 2001
Creator: HEMEZ, F. M.
System: The UNT Digital Library
Small fatigue cracks: mechanics, mechanisms and engineering applications (open access)

Small fatigue cracks: mechanics, mechanisms and engineering applications

Damage-tolerant design and life-prediction methodologies have been practiced for metallic structures for decades, although their application to brittle materials, such as ceramics, and intermetallic alloys, still poses particular problems, primarily because of their extreme flaw-sensitivity.
Date: May 1, 2001
Creator: Ritchie, R. O. & Peters, J. O.
System: The UNT Digital Library
STRUCTURAL HEALTH MONITORING OF WELDED CONNECTIONS (open access)

STRUCTURAL HEALTH MONITORING OF WELDED CONNECTIONS

Structural health monitoring is the implementation of a damage detection strategy for aerospace, civil and mechanical engineering infrastructure. Typical damage experienced by this infrastructure might be the development of fatigue cracks, degradation of structural connections, or bearing wear in rotating machinery. The goal of the research effort reported herein is to develop a robust and cost-effective monitoring system for welded beam-column connections in a moment resisting frame structure. The structural health monitoring solution for this application will integrate structural dynamics, wireless data acquisition, local actuation, micro-electromechanical systems (MEMs) technology, and statistical pattern recognition algorithms. This paper provides an example of the integrated approach to structural health monitoring being undertaken at Los Alamos National Laboratory and summarizes progress to date on various aspects of the technology development.
Date: May 1, 2001
Creator: SOHN, H.; FARRAR, C.; FUGATE, M. & CZARNECKI, J.
System: The UNT Digital Library
VITRIFICATION SYSTEM FOR THE TREATMENT OF PLUTONIUM-BEARING WASTE AT LOS ALAMOS NATIONAL LABORATORY (open access)

VITRIFICATION SYSTEM FOR THE TREATMENT OF PLUTONIUM-BEARING WASTE AT LOS ALAMOS NATIONAL LABORATORY

A glove box vitrification system is being fabricated to process aqueous evaporator bottom waste generated at the Plutonium Facility (TA-55) at Los Alamos National Laboratory (LANL). The system will be the first within the U.S. Department of Energy Complex to routinely convert Pu{sup 239}-bearing transuranic (TRU) waste to a glass matrix for eventual disposal at the Waste Isolation Pilot Plant (WIPP). Currently at LANL, this waste is solidified in Portland cement. Radionuclide loading in the cementation process is restricted by potential radiolytic degradation (expressed as a wattage limit), which has been imposed to prevent the accumulation of flammable concentrations of H{sub 2} within waste packages. Waste matrixes with a higher water content (e.g., cement) are assigned a lower permissible wattage limit to compensate for their potential higher generation of H{sub 2}. This significantly increases the number of waste packages that must be prepared and shipped, thus driving up the costs of waste handling and disposal. The glove box vitrification system that is under construction will address this limitation. Because the resultant glass matrix produced by the vitrification process is non-hydrogenous, no H{sub 2} can be radiolytically evolved, and drums could be loaded to the maximum allowable limit of 40 watts. …
Date: May 1, 2001
Creator: NAKAOKA, R.; VEAZEY, G. & AL, ET
System: The UNT Digital Library
OVERVIEW OF PRESSURE VESSEL DESIGN CRITERIA FOR INTERNAL DETONATION (BLAST) LOADING (open access)

OVERVIEW OF PRESSURE VESSEL DESIGN CRITERIA FOR INTERNAL DETONATION (BLAST) LOADING

Spherical and cylindrical pressure vessels are often used to completely contain the effects of high explosions. These vessels generally fall into two categories. The first includes vessels designed for multiple use ([1]-[6]). Applications of such multiple-use vessels include testing of explosive components and bomb disposal. Because of the multiple-use requirement, response of the vessel is restricted to the elastic range. The second category consists of vessels designed for one-time use only ([7]-[9]). Vessels in this category are typically used to contain accidental explosions and are designed to efficiently utilize the significant plastic energy absorption capacity of ductile materials. Because these vessels may undergo large permanent plastic deformations, they may not be reusable. Ideally one would design a Containment Vessel according to some National or International Consensus Standard, such as the ASME Boiler and Pressure Vessel Code. Unfortunately, however, a number of issues preclude direct use of the ASME Code in its present form to the design of Containment Vessels. These issues are described in Section 2, along with a request for guidance from the PVRC as to a suitable path forward for developing appropriate ASME B&PV design guidance for Containment Vessels. Next, a discussion of the nature of impulsive loading …
Date: May 1, 2001
Creator: DUFFEY, T. A. & RODRIGUEZ, E. A.
System: The UNT Digital Library
Studies of the front end of a neutrino factory (open access)

Studies of the front end of a neutrino factory

A neutrino factory employs muons which are produced, collected, cooled, accelerated and then stored so that their eventual decay produces an intense neutrino beam. A general description may be found in the paper by Geer [S. Geer, Phys. Rev. D, 57, 1 (1998)], and two upcoming Comments on Nuclear and Particle Physics articles [S. Geer, ''Future prospects for muon facilities'', see http://www-mucool.fnal.gov/mcnotes/muc0154.ps; also A. M. Sessler, ''Neutrino Factories: The Facility'', http://www-mucool.fnal.gov/mcnotes/muc0155.pdf]. In this contribution, we use analytic and numerical tools to investigate the performance of the front end of a neutrino factory. This region starts just after the target and ends just prior to the recirculating accelerators. Extensive previous work has resulted in designs used in the Fermilab Study of 1999-2000 and the Brookhaven Study of 2000-2001. Here we explore variations away from these particular designs, seeking possible improvements in final muon output, risk reduction, and ultimate cost. Our studies include changes in the overall front end geometry through optimization of the induction linac design and variations of the rf frequency in the cooling channel acceleration, and initial exploration of the use of helical wiggler fields to increase the range of initial muon energies that are captured.
Date: May 30, 2001
Creator: Fawley, William; Penn, Gregory; Sessler, Andrew & Wurtele, Jonathan
System: The UNT Digital Library
Spin Physics at JLAB in the Resonance Region (open access)

Spin Physics at JLAB in the Resonance Region

I will discuss recent results from Jefferson Lab on the measurement of inclusive spin structure functions in the nucleon resonance region using polarized ammonia NH{sub 3} and polarized {sup 3}He targets. Preliminary results on the first moment of g{_}1(x,Q{sup 2}) for protons, and the generalized Gerasimov-Drell-Hearn integral for neutrons are presented. In addition, first double polarization data on exclusive electroproduction of pi{sup +} for polarized protons will be discussed.
Date: May 1, 2001
Creator: Burkert, V.
System: The UNT Digital Library
An Independent Analysis of a Glovebox Glove Failure Incident (open access)

An Independent Analysis of a Glovebox Glove Failure Incident

None
Date: May 1, 2001
Creator: Lee, S.; Cournoyer, M. & Grundemann, R.
System: The UNT Digital Library
An Evaluation of New High-Resolution Image Collection and Processing Techniques for Estimating Shrub Cover and Detecting Landscape Changes (open access)

An Evaluation of New High-Resolution Image Collection and Processing Techniques for Estimating Shrub Cover and Detecting Landscape Changes

Research funded by the U.S. Department of Defense (DoD), U.S. Department of Energy (DOE), and the U.S. Environmental Protection Agency as part of the Strategic Environmental Research and Development Program (SERDP) evaluated novel techniques for collecting and processing high-resolution images in the Mojave Desert. Several camera types, lens, films, and digital processing techniques were evaluated on the basis of their ability to correctly estimate canopy cover of shrubs. A high degree of accuracy was obtained with photo scales of 1:1000 to 1:4000 and flatbed scanning rates from films or prints of 300 lines per inch or larger. Smaller scale images were of value in detecting retrospective changes in cover of large shrubs, but failed to detect smaller shrubs. New image-processing software, typically used in light microscopy, forensics, and industrial engineering, make it possible to accurately measure areas for total cover of up to four dominant shrub species in minutes compared to hours or days of field work. Canopy cover and individual shrub parameters such as width, length, circumference, and shape factors can be readily measured yielding size distribution histograms and other statistical data on plant community structure. These novel techniques are being evaluated in a four-year study of military training …
Date: May 1, 2001
Creator: Hansen, D.J. & Ostler, W.K.
System: The UNT Digital Library
HYBRID AND HALL-MHD SIMULATIONS OF COLLISIONLESS RECONNECTION: EFFECTS OF PLASMA PRESSURE TENSOR (open access)

HYBRID AND HALL-MHD SIMULATIONS OF COLLISIONLESS RECONNECTION: EFFECTS OF PLASMA PRESSURE TENSOR

In this study we performed two-dimensional hybrid (particle ions, massless fluid electrons) and Hall-MHD simulations of collisionless reconnection in a thin current sheet. Both calculations include the full electron pressure tensor (instead of a localized resistivity) in the generalized Ohm's law to initiate reconnection, and in both an initial perturbation to the Harris equilibrium is applied. First, electron dynamics from the two calculations are compared, and we find overall agreement between the two calculations in both the reconnection rate and the global configuration. To address the issue of how kinetic treatment for the ions affects the reconnection dynamics, we compared the fluid-ion dynamics from the Hall-MHD calculation to the particle-ion dynamics obtained from the hybrid simulation. The comparison demonstrates that off-diagonal elements of the ion pressure tensor are important in correctly modeling the ion out-of-plane momentum transport from the X point. It is that these effects can be modeled efficiently using a particle Hall-MHD simulation method in which particle ions used in a predictor/corrector to implement the ion gyro-radius corrections. We also investigate the micro- macro-scale coupling in the magnetotail dynamics by using a new integrated approach in which particle Hall-MHD calculations are embedded inside a MHD simulation. Initial results …
Date: May 1, 2001
Creator: YIN, L.; WINSKE, D. & AL, ET
System: The UNT Digital Library
Laser Profile Measurements of an H Beam. (open access)

Laser Profile Measurements of an H Beam.

A non-intercepting beam profile monitor for H{sup {minus}} beams is being developed at Brookhaven National Lab. An H{sup {minus}} ion has a first ionization potential of 0.75eV. Electrons can be removed from an H{sup {minus}} beam by passing light from a near-infrared laser through it. Experiments have been performed on the BNL linac to measure the transverse profile of a 750keV beam by using a Nd:YAG laser to photoneutralize narrow slices of the beam. The laser beam is scanned across the ion beam neutralizing the portion of the beam struck by the laser. The electrons are removed from the ion beam and the beam current notch is measured.
Date: May 12, 2001
Creator: Connolly, R.; Cameron, P.; Cupolo, J.; Grau, M.; Kesselman, M.; Liaw, C. J. et al.
System: The UNT Digital Library
Dynamic Analysis of 9975 Shipping Package without Overpack Subjected to 55-Foot Drop (open access)

Dynamic Analysis of 9975 Shipping Package without Overpack Subjected to 55-Foot Drop

This paper discusses the evaluation of the dynamic response of a 9975 shipping package subjected to a load of 55-foot lateral drop without its overpack structure (fiberboard and drum).
Date: May 30, 2001
Creator: Wu, T.
System: The UNT Digital Library
Natural Gas as a Future Fuel for Heavy-Duty Vehicles (open access)

Natural Gas as a Future Fuel for Heavy-Duty Vehicles

In addition to their significant environmental impacts, medium-duty and heavy-duty (HD) vehicles are high volume fuel users. Development of such vehicles, which include transit buses, refuse trucks, and HD Class 6-8 trucks, that are fueled with natural gas is strategic to market introduction of natural gas vehicles (NGV). Over the past five years the Department of Energy's (DOE) Office of Heavy Vehicle Technologies (OHVT) has funded technological developments in NGV systems to support the growth of this sector in the highly competitive transportation market. The goals are to minimize emissions associated with NGV use, to improve on the economies of scale, and to continue supporting the testing and safety assessments of all new systems. This paper provides an overview of the status of major projects under a program supported by DOE/OHVT and managed by Brookhaven National Laboratory. The discussion focuses on the program's technical strategy in meeting specific goals proposed by the N GV industry and the government. Relevant projects include the development of low-cost fuel storage, fueling infrastructure, and HD vehicle applications.
Date: May 14, 2001
Creator: Litzke, Wai-Lin & Wegrzyn, James
System: The UNT Digital Library
Distribution of Chromium Contamination and Microbial Activity in Soil Aggregates (open access)

Distribution of Chromium Contamination and Microbial Activity in Soil Aggregates

None
Date: May 1, 2001
Creator: Tokunaga, Tetsu K.; Wan, Jiamin; Firestone, Mary K.; Hazen, Terry C.; Schwartz, Egbert; Sutton, Stephen R. et al.
System: The UNT Digital Library
YIELD STRESS ANOMALIES, DISLOCATION CORE STRUCTURES AND SUBSTITUTIONAL ALLOYING IN MOLYBDENUM DISILICIDE (open access)

YIELD STRESS ANOMALIES, DISLOCATION CORE STRUCTURES AND SUBSTITUTIONAL ALLOYING IN MOLYBDENUM DISILICIDE

A brief overview of the temperature dependence of yield strength for the different slip systems of MoSi{sub 2} is presented and mechanisms for the yield stress anomaly are discussed. Recent results on the atomistic simulation of the dislocation core structures and mobility are presented next. Finally, we present experimental results on substitutional alloying of polycrystalline MoSi{sub 2} with 1-2 at.% Re, Nb and Al. Re resulted in an order of magnitude increase in compressive strength at 1600 C, Al caused solution softening at near-ambient temperatures, and Nb caused softening at low temperatures and hardening at high temperatures. The quaternary MoSi{sub 2}-Re-Al alloys showed strengthening at elevated temperatures and reduction in flow stress with enhanced plasticity at near-ambient temperatures. The mechanisms of solution hardening and softening are discussed using insight from transmission electron microscopy observations of the dislocation substructures and atomistic simulation results.
Date: May 1, 2001
Creator: MISRA, A.; MITCHELL, T.; BASKES, M. & AL, ET
System: The UNT Digital Library
Optimum Method of Evaporator Pot Liquid Heating and Cooling for Evaporator Cleaning and Recovery Program (open access)

Optimum Method of Evaporator Pot Liquid Heating and Cooling for Evaporator Cleaning and Recovery Program

The Savannah River Site Evaporators have run with limited operation problems for almost 40 years. In October 1999, one evaporator was shut down due to the inability to lift the concentrate solutions from the pot. Different methods of pot liquid heating, cooling, and selection of optimum method were discussed.
Date: May 2, 2001
Creator: Kwon, K.C.
System: The UNT Digital Library
Digital Radiography of a Drop Tested 9975 Radioactive Materials Packaging (open access)

Digital Radiography of a Drop Tested 9975 Radioactive Materials Packaging

This paper discusses the use of radiography as a tool for evaluating damage to radioactive material packaging subjected to regulatory accident conditions. The Code of Federal Regulations, 10 CFR 71, presents the performance based requirements that must be used in the development (design, fabrication and testing) of a radioactive material packaging. The use of various non-destructive examination techniques in the fabrication of packages is common. One such technique is the use of conventional radiography in the examination of welds. Radiography is conventional in the sense that images are caught one at a time on film stock. Most recently, digital radiography has been used to characterize internal damage to a package subjected to the 30-foot hypothetical accident conditions (HAC) drop. Digital radiography allows for real time evaluation of the item being inspected. This paper presents a summary discussion of the digital radiographic technique and an example of radiographic results of a 9975 package following the HAC 30-foot drop.
Date: May 30, 2001
Creator: Blanton, P.S.
System: The UNT Digital Library