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Thermodynamic and nonstoichiometric behavior of the GdBa{sub 2}Cu{sub 3}O{sub x} system.

Description: Electromotive force (EMF) measurements of oxygen fugacities as a function of stoichiometry have been made on the GdBa{sub 2}Cu{sub 3}O{sub x} system in the temperature range {approximately}400-600 C by means of an oxygen titration technique with an yttria-stabilized zirconia electrolyte. Equations for the variation of oxygen partial pressure with composition and temperature have been derived from our EMF measurements. The shape of the 400 C isotherms as a function of oxygen stoichiometry for the Gd and Nd cuprate systems suggests the presence of miscibility gaps at values of x that are higher than those in the YBa{sub 2}Cu{sub 3}O{sub x} system. For a given oxygen stoichiometry, oxygen partial pressures above Gd-123 and Nd-123 cuprate systems are higher (above x = 6.5) than that for the Y-123 system. A thermodynamic assessment and intercomparison of our partial pressure measurements with the results of related measurements will be presented.
Date: September 29, 1998
Creator: Tetenbaum, M.
Partner: UNT Libraries Government Documents Department

Repowering with clean coal technologies

Description: Repowering with clean coal technology can offer significant advantages, including lower heat rates and production costs, environmental compliance, incremental capacity increases, and life extension of existing facilities. Significant savings of capital costs can result by refurbishing and reusing existing sites and infrastructure relative to a greenfield siting approach. This paper summarizes some key results of a study performed by Parsons Power Group, Inc., under a contract with DOE/METC, which investigates many of the promising advanced power generation technologies in a repowering application. The purpose of this study was to evaluate the technical and economic results of applying each of a menu of Clean Coal Technologies in a repowering of a hypothetical representative fossil fueled power station. Pittsburgh No. 8 coal is used as the fuel for most of the cases evaluated herein, as well as serving as the fuel for the original unrepowered station. The steam turbine-generator, condenser, and circulating water system are refurbished and reused in this study, as is most of the existing site infrastructure such as transmission lines, railroad, coal yard and coal handling equipment, etc. The technologies evaluated in this study consisted of an atmospheric fluidized bed combustor, several varieties of pressurized fluid bed combustors, several types of gasifiers, a refueling with a process derived fuel, and, for reference, a natural gas fired combustion turbine-combined cycle.
Date: February 1, 1996
Creator: Freier, M.D.; Buchanan, T.L.; DeLallo, M.L. & Goldstein, H.N.
Partner: UNT Libraries Government Documents Department

Application of a species-selective Penning gauge to the measurement of neon and hydrogen-isotope partial pessures in the plasma boundary

Description: A species-selective Penning gauge, previously applied to He partial pressures, has been applied to the detection of small concentrations of Ne in a D{sub 2} gas. This is important for the study of Ne in the boundary region of magnetic fusion devices, where this impurity is deliberately injected to enhance the radiated power in that region. The application of the technique to the detection of the partial pressure of a minority hydrogen isotope is also examined. In this latter application, the detection system and the data analysis are more complex, because of the proximity of the spectral lines from the isotopes. In both applications, it is found that use of a proper detection scheme permits reliable measurements of concentrations as low as 0.5% of the minority neutral species, without requiring changes to the standard commercial Penning gauge setup.
Date: June 1, 1996
Creator: Klepper, C.C.; Hillis, D.L. & Wade, M.R.
Partner: UNT Libraries Government Documents Department

Pressure driven particulate flows

Description: Numerical simulations of pressure-driven particulate Stokes flows are performed in cylindrical and rectangular conduits using a parallel boundary element code. Spherical particles are randomly placed in the conduits and a pressure drop between the ends of the conduits is imposed by the boundary conditions to induce a Poiseuille-like flow field. The instantaneous velocities of the particles are then calculated, as well as the additional pressure drop necessary to maintain a constant flow rate. Because the results depend on the spatial distribution of the particles, several random configurations of particles are examined for each case. Depending on two different interpretations of the numerical results, the solid phase can be represented as either leading or lagging the fluid phase. Both of the analyses and interpretations are presented.
Date: March 1, 1996
Creator: Ingher, M.S. & Mondy, L.A.
Partner: UNT Libraries Government Documents Department

Nonlinear elastic properties of the piezoelectric crystal: GaPO{sub 4}

Description: These properties were investigated at high pressure/ordinary temperature and low temperature/ordinary pressure. Pressure dependence of the elastic constants (nonlinear behavior) shows that the GaPO{sub 4} crystal undergoes a structural phase transition around 14 GPa. This is tentatively correlated with a potential instability observed at low temperature (50 K).
Date: 1996-23~
Creator: Zarembowitch, A.; Palmier, D.; Polian, A. & Grimsditch, M.
Partner: UNT Libraries Government Documents Department

Permeability of fractured tuff as functions of temperature and confining pressure

Description: Understanding the transport properties of water through fractured rock is critical to predicting and modeling the hydrothermal performance of a geologic nuclear waste repository. Previous studies indicate that intact Topopah Spring tuff from Yucca Mountain, Nevada has a low permeability, {approximately} 1 {times} 10 {sup {minus}18} m{sup 2} ({approximately}1 microDarcy). A single fracture in the tuff increases the permeability to {approximately}100 {times}10{sup {minus}15} m{sup 2} (hundreds of milliDarcies). However, fracture healing may occur when high temperature water flows through the fracture lowering the permeability by one or more orders of magnitude. We report progress on laboratory experiments on permeability of fractured Topopah Spring tuff as functions of confining pressure, temperature, and water/rock ratio.
Date: October 1, 1994
Creator: Roberts, J.J. & Lin, Wunan
Partner: UNT Libraries Government Documents Department

Atomic level microstructural characterization by APFIM

Description: Atom probe field ion microscopy has been used to characterize Ni aluminides in addition to changes in microstructure of pressure vessel steels as a result of exposure to neutron irradiation. Ultrafine intragranular Cu precipitates and P segregation to grain and lath boundaries have been quantified in the pressure vessel steels. In boron-doped Ni{sub 3}Al, the B additions were found to segregate to dislocations, low angle boundaries, antiphase boundaries, stacking faults, and grain boundaries. In boron-doped NiAl, B segregation to grain boundaries and ultrafine MB{sub 2} precipitates were observed. In Mo-doped NiAl, enrichments of Mo, C, N/Si, B, and Fe were observed at the grain boundaries together with Mo precipitates and low Mo matrix solubility.
Date: October 1, 1996
Creator: Miller, M. K.
Partner: UNT Libraries Government Documents Department

Extents of alkane combustion during rapid compression leading to single and two stage ignition

Description: Extents of reactant consumption have been measured during the course of spontaneous ignition following rapid compression of N-pentane and N-heptane and also of PRF 60 (N-heptane = i-octane, 2.2.4 trimethylpentane) in stoichiometric mixtures with air. Compressed gas temperatures of 720-750 K and 845-875 K were studied at reactant densities of 131 mol m{sup minus 3}. At the lower gas temperature there was no evidence of reactant consumption during the course of the compression stroke. Two-stage ignition occurred at these temperatures, but only modest proportions of n-pentane were consumed during the first stage (< 15%) whereas about 40% of proportions of n- heptane reacted under the same conditions. At the higher compressed gas temperature the oxidation of n-pentane began only after the piston had stopped, whereas more than 30% of the n-heptane had already been consumed in the final stage of the compression stroke. The behavior of the PRF 60 mixture differed somewhat from that of N- pentane despite the similarly of the research octane numbers. Although there was a preferential oxidation of n-heptane at T{sub c} = 850K, which persisted throughout the early development of spontaneous ignition during the post-compression period, oxidation of both components of the PRF 60 mixture began before the piston had stopped. Numerical simulations of the spontaneous ignition under conditions resembling those of the rapid compression experiments show that the predicted reactivity from detailed kinetics are consistent with the observed features. Insights into the kinetic interactions that give rise to the relative reactivities of the primary reference fuel components are established
Date: February 1, 1996
Creator: Cox, A.; Griffiths, J.F.; Mohamed, C.; Curran, H.; Pitz, W.J. & Westbrook, C.K.
Partner: UNT Libraries Government Documents Department

A New Analytical Solution for Diaphragm Deflection and its Application to a Surface-Micromachined Pressure Sensor

Description: An analytical solution for large deflections of a clamped circular diaphragm with built-in stress is presented. The solution is directly applicable to micromachined pressure sensors. The solution is compared to finite element analysis results and experimental data from a surface-micromachined pressure sensor.
Date: March 9, 1999
Creator: Bitsie, F.; Eaton, W.P.; Plummer, D.W. & Smith, J.H.
Partner: UNT Libraries Government Documents Department

A level control model for BWR emergency procedure guidelines

Description: The level control during an Anticipated Transient Without Scram (ATWS) event in a BWR as prescribed in the Emergency Procedure Guidelines (EPG) is a difficult task for the operator for he has to keep the water level at the top of active fuel (TAF) without uncovering the reactor core. Also the computer simulation of EPG level control will require many trial and error calculations with the Emergency Core Cooling System (ECCS). A level control system model has been developed and implemented in the RAMONA-4B code in order to simulate the EPG level control without iterations. The model has been extensively tested and the results demonstrate that the model can simulate the EPG level control strategy. The calculations also show that the level control system will speed up the boron circulation to shut down the reactor sooner than the manual control. Furthermore, the suppression pool temperature is predicted to remain within the Technical Specification limit during a MSIV closure ATWS with the proposed level control strategy. 3 refs., 11 figs., 1 tab.
Date: October 1, 1996
Creator: Cheng, H.S. & Rohatgi, U.S.
Partner: UNT Libraries Government Documents Department

Validation of favor code linear elastic fracture solutions for finite-length flaw geometries

Description: One of the current tasks within the US Nuclear Regulatory Commission (NRC)-funded Heavy Section Steel Technology Program (HSST) at Oak Ridge National Laboratory (ORNL) is the continuing development of the FAVOR (Fracture, analysis of Vessels: Oak Ridge) computer code. FAVOR performs structural integrity analyses of embrittled nuclear reactor pressure vessels (RPVs) with stainless steel cladding, to evaluate compliance with the applicable regulatory criteria. Since the initial release of FAVOR, the HSST program has continued to enhance the capabilities of the FAVOR code. ABAQUS, a nuclear quality assurance certified (NQA-1) general multidimensional finite element code with fracture mechanics capabilities, was used to generate a database of stress-intensity-factor influence coefficients (SIFICs) for a range of axially and circumferentially oriented semielliptical inner-surface flaw geometries applicable to RPVs with an internal radius (Ri) to wall thickness (w) ratio of 10. This database of SIRCs has been incorporated into a development version of FAVOR, providing it with the capability to perform deterministic and probabilistic fracture analyses of RPVs subjected to transients, such as pressurized thermal shock (PTS), for various flaw geometries. This paper discusses the SIFIC database, comparisons with other investigators, and some of the benchmark verification problem specifications and solutions.
Date: April 1, 1995
Creator: Dickson, T.L.; Keeney, J.A. & Bryson, J.W.
Partner: UNT Libraries Government Documents Department

Irrecoverable pressure loss coefficients for two elbows in series with various orientation angles and separation distances

Description: Test data is described for two ninety degree elbows that are in series for a piping network. Both elbows had a radius of curvature of 1.2. Three relative angles and seven different separation distances were investigated. The overall irrecoverable pressure loss for the two elbows is characterized relative to the irrecoverable pressure loss for a single elbow. In addition to providing design guidance relative to the net irrecoverable pressure loss for multiple elbows, the data provides a data base for helping qualify computational fluid dynamics (CFD) computer codes used to predict the irrecoverable pressure loss in piping systems.
Date: May 1, 1997
Creator: Coffield, R.D.; McKeown, P.T. & Hammond, R.B.
Partner: UNT Libraries Government Documents Department

A CMOS-compatible, surface-micromachined pressure sensor for aqueous ultrasonic application

Description: A surface micromachined pressure sensor array is under development at the Integrated Micromechanics, Microsensors, and CMOS Technologies organization at Sandia National Laboratories. This array is designed to sense absolute pressures from ambient pressure to 650 psia with frequency responses from DC to 2 MHz. The sensor is based upon a sealed, deformable, circular LPCVD silicon nitride diaphragm. Absolute pressure is determined from diaphragm deflection, which is sensed with low-stress, micromechanical, LPCVD polysilicon piezoresistors. All materials and processes used for sensor fabrication are CMOS compatible, and are part of Sandia`s ongoing effort of CMOS integration with Micro-ElectroMechanical Systems (MEMS). Test results of individual sensors are presented along with process issues involving the release etch and metal step coverage.
Date: December 1994
Creator: Eaton, W. P. & Smith, J. H.
Partner: UNT Libraries Government Documents Department

Simultaneous neutron and gamma spectrum adjustment

Description: The spectrum adjustment procedure was extended to simultaneous neutron and gamma spectrum adjustment, and the feasibility of this technique is demonstrated in the analysis of HFIR dosimetry experiments. Conditions in which gamma rays may contribute considerably to radiation damage in steels are discussed. Beryllium helium accumulation fluence monitors (HAFMs) were found to be good monitors in gamma fields of intensities high enough to contribute to steel embrittlement. Use of {sup 237}Np, {sup 238}U, and {sup 9}Be HAFM as gamma dosimeters is proposed for high-dose irradiations in high-energy, high-intensity gamma fields.
Date: October 1, 1996
Creator: Remec, I.
Partner: UNT Libraries Government Documents Department

Stability time of a DT-filled cryogenic ICF target in a high vacuum environment

Description: Following the successful pressure loading with DT of a thin-walled plastic inertial fusion target shell (such as those designed for use at the OMEGA facility at the University of Rochester`s Laboratory for Laser Energetics (UR/LLE)), continual care must be taken to safeguard the shell from being exposed to unacceptable pressure differentials across its wall. In particular, once the DT has been condensed into a liquid or solid phase and the outside pressure has been reduced, the target must be maintained below some upper cutoff temperature such that the vapor pressure of the DT is below the bursting pressure for the shell. Through the process of {beta}-decay the DT self-heats, but while the shell is in a high vacuum environment (P {much_lt} 0.8 Pa (6 mtorr) for the OMEGA layering sphere) there is only a negligible heat loss mechanism. This will cause the temperature to increase. A calculation has been done to estimate the rate of temperature increase of the loaded target under high vacuum conditions. A functional form for calculating the target`s temperature increase given its starting temperature is presented. An overall result is that under high vacuum conditions the DT changes from a solid at 10 K to a liquid at 37 K (T{sub c} = 39.4 K) in about 19 minutes. This holding time is significantly less if the initial temperature is higher, the initial state is liquid, or the upper allowed temperature is lower. Simplifying assumptions which were made and their impact on interpreting the results of this calculation are discussed.
Date: December 1, 1998
Creator: Ebey, P.S. & Hoffer, J.K.
Partner: UNT Libraries Government Documents Department

The effect of pressure on annular flow pressure drop in a small pipe

Description: New experimental data was obtained for pressure drop and entrainment for annular up-flow in a vertical pipe. The 9.5 mm. pipe has an L/D ratio of 440 to insure fully developed annular flow. The pressure ranged from 140 kPa to 660 kPa. Therefore the density ratio was varied by a factor of four approximately. This allows the investigation of the effect of pressure on the interfacial shear models. Gas superficial velocities between 25 and 126 m/s were tested. This extends the range of previous data to higher gas velocities. The data were compared with well known models for interfacial shear that represent the state of the art. Good results were obtained when the model by Asali, Hanratty and Andreussi was modified for the effect of pressure. Furthermore an equivalent model was obtained based on the mixing length theory for rough pipes. It correlates the equivalent roughness to the film thickness.
Date: September 1, 1996
Creator: de Bertodano, M.A.L.; Beus, S.G. & Shi, Jian-Feng
Partner: UNT Libraries Government Documents Department

Proceedings of the IAEA specialists` meeting on cracking in LWR RPV head penetrations

Description: This report contains 17 papers that were presented in four sessions at the IAEA Specialists` meeting on Cracking in LWR RPV Head Penetrations held at ASTM Headquarters in Philadelphia on May 2-3, 1995. The papers are compiled here in the order that presentations were made in the sessions, and they relate to operational observations, inspection techniques, analytical modeling, and regulatory control. The goal of the meeting was to allow international experts to review experience in the field of ensuring adequate performance of reactor pressure vessel (RPV) heads and penetrations. The emphasis was to allow a better understanding of RPV material behavior, to provide guidance supporting reliability and adequate performance, and to assist in defining directions for further investigations. The international nature of the meeting is illustrated by the fact that papers were presented by researchers from 10 countries. There were technical experts present form other countries who participated in discussions of the results presented. This present document incorporates the final version of the papers as received from the authors. The final chapter includes conclusions and recommendations. Individual papers have been cataloged separately.
Date: July 1, 1996
Creator: Pugh, C.E.; Raney, S.J. & Oak Ridge National Lab., TN (United States)]
Partner: UNT Libraries Government Documents Department

The shock Hugoniot of liquid hydrazine in the pressure range of 3.1 to 21.4 GPa

Description: Impedance matching was used; the technique was similar to Richard Dick`s. Shock pressures were produced using a plane wave explosive driver with different explosives and different reference materials against liq. hydrazine. Velocity of shock wave in the liquid and free surface velocity of the reference material were measured using different pin contact techniques. The experimental Hugoniot appears smooth, with no indication of a phase change. The shock Hugoniot of liq. hydrazine was compared against 3 other liquid Hugoniots (liq. NH3, water, CCl4) and is closest to that for water and in between NH3 and CCl4. The hydrazine Hugoniot was also compared to the ``Universal`` Hugoniot for liquids. This universal Hugoniot is not a good approximation for the liq. hydrazine in this pressure range.
Date: October 1, 1996
Creator: Garcia, B.O. & Persson, P-A.
Partner: UNT Libraries Government Documents Department

An autonomous agent for on-machine acceptance of machined components

Description: In recent years, manufacturers of high precision mechanical parts have been required to produce increasingly complex designs, in smaller lot sizes, with improved quality. These requirements demand lower process costs, shorter development cycles and more accurate manufacturing technologies. To meet these demands, manufacturers are attempting to both improve process quality and provide better CAD/CAM integration. The technique of on-machine acceptance provides one mechanism for improving the part inspection and verification process. This approach allows one machine and one process capability model to be used for both fabrication and inspection, reducing capital cost and overall cycle time. However, the on-machine acceptance technique possesses greater potential than as simply an alternative mechanism for verifying part geometry. If the inspection capability information generated by on-machine acceptance processes can be made available to designers, it can be used to create a design-for-inspectability environment and help realize the benefits of concurrent 2048 engineering. This paper proposes a novel architecture which integrates on-machine acceptance with an agent-based concurrent design environment, for reducing both the cost and production time for high quality, small lot size, mechanical parts. This work has focused on the production of stainless steel pressure vessels at the Integrated Manufacturing Technology Laboratory (IMTL) manufacturing cell, located at Sandia National Laboratories, California.
Date: December 31, 1995
Creator: Panceerella, C.M.; Hazelton, A.J. & Frost, H.R.
Partner: UNT Libraries Government Documents Department

Assessing alternative conceptual models of fracture flow

Description: The numerical code TOUGH2 was used to assess alternative conceptual models of fracture flow. The models that were considered included the equivalent continuum model (ECM) and the dual permeability (DK) model. A one-dimensional, layered, unsaturated domain was studied with a saturated bottom boundary and a constant infiltration at the top boundary. Two different infiltration rates were used in the studies. In addition, the connection areas between the fracture and matrix elements in the dual permeability model were varied. Results showed that the two conceptual models of fracture flow produced different saturation and velocity profiles-even under steady-state conditions. The magnitudes of the discrepancies were sensitive to two parameters that affected the flux between the fractures and matrix in the dual permeability model: (1) the fracture-matrix connection areas and (2) the capillary pressure gradients between the fracture and matrix elements.
Date: March 1, 1995
Creator: Ho, C.K.
Partner: UNT Libraries Government Documents Department

Recent Progress on the Standardized DOE Spent Nuclear Fuel Canister

Description: The Department of Energy (DOE) has developed a set of containers for the handling, interim storage, transportation, and disposal in the national repository of DOE spent nuclear fuel (SNF). This container design, referred to as the standardized DOE SNF canister or standardized canister, was developed by the Department's National Spent Nuclear Fuel Storage Program (NSNFP) working in conjunction with the Office of Civilian Radioactive Waste Management (OCRWM) and the DOE spent fuel sites. This canister had to have a standardized design yet be capable of accepting virtually all of the DOE SNF, be placed in a variety of storage and transportation systems, and still be acceptable to the repository. Since specific design details regarding the storage, transportation, and repository disposal of DOE SNF were not finalized, the NSNFP recognized the necessity to specify a complete DOE SNF canister design. This allowed other evaluations of canister performance and design to proceed as well as providing standardized canister users adequate information to proceed with their work. This paper is an update of a paper presented to the 1999 American Nuclear Society of Mechanical Engineers (ASME) Pressure Vessels and Piping (PVP) Conference. It discusses recent progress achieved in various areas to enhance acceptance of this canister not only by the DOE complex but also fabricators and regulatory agencies.
Date: May 7, 2002
Creator: Morton, D.K.; Snow, S.D.; Rahl, T.E.; Hill, T.J. (INEEL) & Morissette, R.P. (Beckman and Associates, Inc.)
Partner: UNT Libraries Government Documents Department


Description: In this study, we present nano-scale investigations of point defect dynamics in perovskite oxides by correlated atomic resolution high angle annular dark field imaging (HAADF) and electron energy loss spectroscopy (EELS). The point defect dynamics and interactions during in-situ reduction in the microscope column are analyzed. In particular, oxygen vacancy creation, diffusion and clustering are studied, as oxygen vacancies comprise the majority of the point defects present in these perovskite oxide systems [1]. The results have been acquired using the JEOL2010F, a STEM/TEM, equipped with a 200 keV field emission gun, a high angle annular dark field detector and a post column Gatan imaging filter (GIF). The combination of the Z-contrast and EELS techniques [2] allows us to obtain direct images (spatial resolution of 2 {angstrom}) of the atomic structure and to correlate this information with the atomically resolved EELS information (3s acquisition time, 1.2 eV energy resolution). In-situ heating of the material is performed in a Gatan double tilt holder with a temperature range of 300 K-773 K at an oxygen partial pressure of P{sub O{sub 2}} = 5 * 10{sup -8} Pa.
Date: August 4, 2002
Creator: KLIE,R.F.; BROWNING,N.D. & ZHU,Y.
Partner: UNT Libraries Government Documents Department

Passive Corrosion Behavior of Alloy 22 in Multi-Ionic Aqueous Environments

Description: In current waste packaging design, Alloy 22 (Ni-22Cr-13Mo-3W-3Fe) has been chosen as the candidate materials to fabricate a 2 cm outer layer of the high-level nuclear waste containers, as part of proposed geological repository at Yucca Mountain, Nevada. During the repository period, the container materials will be subject to the corrosion due to its exposure to the multi-ionic aqueous environments. Although Alloy 22 has demonstrated excellent corrosion resistance, but accumulation of small yearly corrosion rate for 10,000 or more years can be significant enough. The goal of this research is to seek alternative techniques to obtain a reasonably confident corrosion rate determination, since the conventional weight loss technique requires many years to achieve a detectable weight loss in Alloy 22 samples. This paper will discuss the latest experiment results in using potentiostatic technique to determine passive dissolution rates.
Date: June 3, 2002
Creator: Lian, T.; Estill, J.C.; Hust, G.A.; Fix, D.V. & Rebak, R.B.
Partner: UNT Libraries Government Documents Department


Description: Developing an understanding of the processes that control the H-mode transport barrier is motivated by the significant impact this small region (typically &lt;2% of the minor radius) can have on overall plasma performance. Conditions at the inner edge of the H-mode transport barrier can strongly influence the overall energy confinement, and the maximum density, and therefore fusion power, that can be achieved with the typically flat H-mode density profiles [1,2]. The ELM instability, which usually regulates the pressure gradient in the H-mode edge, can result in large power loads to, and erosion of, the divertor targets in a reactor scale device [3]. The goal of H-mode pedestal research at DIII-D is to: (1) develop a physics based model that would allow prediction of the conditions at the top of the H-mode pedestal, (2) develop an understanding of processes which control Type I ELM effects in the core and divertor, and (3) explore alternatives to the Type I ELM regime.
Date: July 1, 2001
Partner: UNT Libraries Government Documents Department