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Articles 1 - 30 of 159

Full-Text Articles in Nuclear Engineering

Interdigital Capacitance Local Non-Destructive Examination Of Nuclear Power Plant Cable For Aging Management Programs, S. W. Glass, L. S. Fifield, Nicola Bowler, Aishwarya Sriraman, W. C. Palmer May 2018

Interdigital Capacitance Local Non-Destructive Examination Of Nuclear Power Plant Cable For Aging Management Programs, S. W. Glass, L. S. Fifield, Nicola Bowler, Aishwarya Sriraman, W. C. Palmer

Materials Science and Engineering Publications

This Pacific Northwest National Laboratory milestone report describes progress to date on the investigation of non-destructive test methods focusing on local cable insulation and jacket testing using an interdigital capacitance (IDC) approach. Earlier studies have assessed a number of non-destructive examination (NDE) methods for bulk, distributed, and local cable tests. A typical test strategy is to perform bulk assessments of the cable response using dielectric spectroscopy, Tan , or partial discharge followed by distributed tests like time domain reflectometry or frequency domain reflectometry to identify the most likely defect location followed by a local test that can include visual inspection, indenter ...


Analysis Of High Temperature Effects On Piezoelectric Based Ultrasonic Transducers, Prathamesh Bilgunde Jan 2018

Analysis Of High Temperature Effects On Piezoelectric Based Ultrasonic Transducers, Prathamesh Bilgunde

Graduate Theses and Dissertations

Under sodium viewing (USV) using ultrasonic pulse-echo techniques offers the potential for the inspection of generation IV, liquid sodium-cooled fast reactors (SFRs) at the hot stand-by temperature (260C). However, the harsh environment effects on the transducer reduce the ultrasonic signal strength which also limits the probability of detection (POD) of the defects.

Current work presents a unified modeling and measurement-based methodology to analyze the high temperature effects on the transducer components. Resonance analysis-based characterization has shown that the conventional d33 piezoelectric parameter is not a sufficient condition to estimate resonance characteristics of high temperature ultrasonic transducers. A full piezoelectric material ...


Scaled Experiment Investigating Sonomechanically Enhanced Inert Gas Sparging Mass Transfer, Floren Rubio, Leonard J. Bond, Edward Blandford Dec 2017

Scaled Experiment Investigating Sonomechanically Enhanced Inert Gas Sparging Mass Transfer, Floren Rubio, Leonard J. Bond, Edward Blandford

Aerospace Engineering Publications

One of the leading advanced reactor concepts is the fluoride salt high temperature reactor (FHR) currently under investigation. This design utilizes a fluoride molten salt, flibe (2 LiF/BeF2), as the primary coolant. One challenge of employing flibe as a coolant is the production and release of tritium. The FHR community is currently investigating various techniques to solve this tritium management challenge. One of the methods investigated is inert gas sparging which has been investigated during the Molten Salt Reactor Experiment (MSRE) in the 1960’s and 1970’s. To enhance the efficiency of this technique, high power ultrasonics can ...


Transcranial Magnetic Stimulation-Coil Design With Improved Focality, Priyam Rastogi, E. G. Lee, Ravi L. Hadimani, David C. Jiles Jan 2017

Transcranial Magnetic Stimulation-Coil Design With Improved Focality, Priyam Rastogi, E. G. Lee, Ravi L. Hadimani, David C. Jiles

Electrical and Computer Engineering Publications

Transcranial Magnetic Stimulation (TMS) is a technique for neuromodulation that can be used as a non-invasive therapy for various neurological disorders. In TMS, a time varying magnetic field generated from an electromagnetic coilplaced on the scalp is used to induce an electric field inside the brain. TMS coilgeometry plays an important role in determining the focality and depth of penetration of the induced electric field responsible for stimulation. Clinicians and basic scientists are interested in stimulating a localized area of the brain,while minimizing the stimulation of surrounding neural networks. In this paper, a novel coil has been proposed, namely ...


Survey Of Advanced Nuclear Technologies For Potential Applications Of Sonoprocessing, Floren Rubio, Edward D. Blanford, Leonard J. Bond Sep 2016

Survey Of Advanced Nuclear Technologies For Potential Applications Of Sonoprocessing, Floren Rubio, Edward D. Blanford, Leonard J. Bond

Aerospace Engineering Publications

Ultrasonics has been used in many industrial applications for both sensing at low power and processing at higher power. Generally, the high power applications fall within the categories of liquid stream degassing, impurity separation, and sonochemical enhancement of chemical processes. Examples of such industrial applications include metal production, food processing, chemical production, and pharmaceutical production. There are many nuclear process streams that have similar physical and chemical processes to those applications listed above. These nuclear processes could potentially benefit from the use of high-power ultrasonics. There are also potential benefits to applying these techniques in advanced nuclear fuel cycle processes ...


Ultrasonic Testing Of A Nuclear Fuel Cladding Pipe, Modelization With A Hybrid Method And Experiments, Florian Lyonnet, Didier Cassereau, Andmarie-Françoise Cugnet Jan 2016

Ultrasonic Testing Of A Nuclear Fuel Cladding Pipe, Modelization With A Hybrid Method And Experiments, Florian Lyonnet, Didier Cassereau, Andmarie-Françoise Cugnet

Review of Progress in Quantitative Nondestructive Evaluation

Nuclear Fuel cladding pipes are long and thin tubes made of zirconium-alloy whose purpose is to confine the fissile material in a nuclear reactor. During their 3 year cycle in the reactor's core they must maintain their integrity while enduring severe stresses (heat, corrosion and irradiation). Nondestructive evaluations are performed at several stages of the manufacturing process. ASTM International provides recommendations regarding the Ultrasonic Testing (UT) of zirconium cladding pipes at the end of the production line[1]. The recommended setup is a pulse-echo immersion testing at frequency higher than 5 MHz where transverse and longitudinal calibration notches are ...


Non Destructive Evaluation Of Containment Walls In Nuclear Power Plants, V. Garnier, C. Payan, Martin Lott, Nari Ranaivamonana, Jp Balayssac, E. Larose, Yuxiang Zhang, J. Saliba, A. Boniface, Z. M. Sbartai, Bogdan Piwakowski, Charles Ciccarone, Hamid Hafid, Jean Marie Henault, Florian Ouvrier Buffet Jan 2016

Non Destructive Evaluation Of Containment Walls In Nuclear Power Plants, V. Garnier, C. Payan, Martin Lott, Nari Ranaivamonana, Jp Balayssac, E. Larose, Yuxiang Zhang, J. Saliba, A. Boniface, Z. M. Sbartai, Bogdan Piwakowski, Charles Ciccarone, Hamid Hafid, Jean Marie Henault, Florian Ouvrier Buffet

Review of Progress in Quantitative Nondestructive Evaluation

Two functions are regularly tested on the containment walls in order to anticipate a possible accident. The first is mechanical to resist at a possible internal over-pressure and the second is to prevent leakage. The reference accident LLOCA (Large Loss of Coolant Accident) is the rupture of a pipe in the primary circuit of a nuclear plant. In this case, the pressure and temperature can reach 5 bar and 180°C in 20 seconds.

The national project ‘Non-destructive testing of the containment structures of nuclear plants’ aims at studying the non-destructive techniques capable to evaluate the concrete properties and its ...


Use Of Guided Wave Inspections To Monitor The Integrity Of Nuclear Power Station Boilers, P. Jackson, P. J. Mudge, K. J. Thornicroft, A. G. Haig, R. Sanderson, E. Hutchison, C. R. A. Scheider Jan 2016

Use Of Guided Wave Inspections To Monitor The Integrity Of Nuclear Power Station Boilers, P. Jackson, P. J. Mudge, K. J. Thornicroft, A. G. Haig, R. Sanderson, E. Hutchison, C. R. A. Scheider

Review of Progress in Quantitative Nondestructive Evaluation

This paper describes a ground-breaking application of guided wave testing for the nuclear power industry. Hartlepool and Heysham 1 power stations in the UK contain boilers of a unique ‘pod’ design in which the spiral boiler tubes are supported from above by a central vertical ‘spine’, which is a tubular component approximately 520mm in diameter and 21m long with complex changes in cross-section and attachments along its length. There are 32 boilers in the two stations. The gas which has passed through the reactor core flows down over the boiler tubes, heating the water inside. Only the top 2m of ...


Capacitive Sensing For Nuclear Power Plant Cable Insulation Assessment, Nicola Bowler, Shuaishuai Liu, Michael I. Byler, Leonard S. Fifield Jan 2016

Capacitive Sensing For Nuclear Power Plant Cable Insulation Assessment, Nicola Bowler, Shuaishuai Liu, Michael I. Byler, Leonard S. Fifield

Review of Progress in Quantitative Nondestructive Evaluation

The ability to evaluate, nondestructively, the material state of insulation polymers widely employed in aged control and power cables has been identified as important In the process of routine safety inspection and safety inspection for license renewal of aging Light Water Reactor Nuclear Power Plants (NPPs) in the United States [1]. The present industry standard is that the insulation polymer breaking strain (or elongation-at-break, EAB) should be no less than 50% of that value measured on the pristine material, for the aged insulation polymer to be fit for service. Measurement of EAB is destructive, the method requires a relatively large ...


Verification And Validation Of Computational Models For Ultrasonic Testing, Gerges Dib, Michael R. Larche, Aaron A. Diaz, Susan L. Crawford, Michael T. Anderson Jan 2016

Verification And Validation Of Computational Models For Ultrasonic Testing, Gerges Dib, Michael R. Larche, Aaron A. Diaz, Susan L. Crawford, Michael T. Anderson

Review of Progress in Quantitative Nondestructive Evaluation

The Pacific Northwest National Laboratory (PNNL) is conducting confirmatory research for the U.S. Nuclear Regulatory Commission (NRC) for the verification and validation of computational models used in ultrasonic testing (UT). This paper discusses some of the findings obtained from simple geometrical reflectors in isotropic, fine-grained, homogeneous materials with conventional ultrasonic transducers. A total of 348 ultrasonic raster scans were acquired using pulse-echo conventional probes with different diameters, beam angles, wave modalities, and frequencies. The raster scans contained reflections from machined notches (flaws) of different sizes and orientations. High frequency pencil beam models, and flaw scattering models employing the Kirchhoff ...


A Hybrid Technique For Modelling The Ultrasonic Response From Surface-Breaking Defects, Richard Phillips, David Duxbury, Peter Huthwaite, Michael Lowe Jan 2016

A Hybrid Technique For Modelling The Ultrasonic Response From Surface-Breaking Defects, Richard Phillips, David Duxbury, Peter Huthwaite, Michael Lowe

Review of Progress in Quantitative Nondestructive Evaluation

Computational modelling is an efficient and cost effective alternative to experimental data collection for the design and justification of ultrasonic non-destructive inspections. Semi-analytical models are commonly used within the nuclear industry, however they place limitations on the size and geometrical complexity of the defect that can be modelled, as well as on inspection parameters such as mode and frequency. The inability to quantify the effect of increased complexity on an ultrasonic inspection regularly leads to a rise in the conservatism of the inspection sensitivity, which increases the probability of reporting innocuous defects.

The Finite Element Method (FEM) provides the capability ...


Characteristic Of Pulsed Eddy Current Signal Pattern To Detect Wall Thinning Of Carbon Steel Tube, D. G. Park, M. B. Kishore, D. H. Lee Jan 2016

Characteristic Of Pulsed Eddy Current Signal Pattern To Detect Wall Thinning Of Carbon Steel Tube, D. G. Park, M. B. Kishore, D. H. Lee

Review of Progress in Quantitative Nondestructive Evaluation

The pipelines used under high pressure and high temperatures in nuclear power plants, oil and gas, petrochemical and other energy related industries are made of ferromagnetic carbon steel. In order to increase the efficiency, the pipelines are always covered with low conductive thermal insulators to refrain from thermal emission and absorption and externally protected by cladding sheets made of aluminum alloy, stainless steel or galvanized steel. Non Destructive Technique (NDT) methods that are capable of detecting the wall thinning and defects without removing the insulation are necessary [1]. In this study we developed a Pulsed Eddy Current (PEC) system to ...


Through-Wall Phased Array Imaging Of Small Surface-Breaking Cracks, Chao Zhang, Peter Huthwaite, Michael J. S. Lowe Jan 2016

Through-Wall Phased Array Imaging Of Small Surface-Breaking Cracks, Chao Zhang, Peter Huthwaite, Michael J. S. Lowe

Review of Progress in Quantitative Nondestructive Evaluation

Accurate and reliable measurements of small surface-breaking cracks are becoming increasingly important in safety-critical components such as in nuclear power plants, because of the desire for increased operational lifetimes. With great coverage and low cost, the use of imaging to find and size surface-breaking cracks with data from ultrasonic phased arrays is becoming more attractive. For the phased array imaging, both the array configuration and the technique used to generate the images from the measurements are key factors in the image quality and sizing accuracy. Thus, the selection of a proper imaging technique is essential to ensure accurate results for ...


Testing Piezoelectric Sensors In A Nuclear Reactor Environment, Brian Reinhardt, Andy Suprock, Bernhard Tittmann Jan 2016

Testing Piezoelectric Sensors In A Nuclear Reactor Environment, Brian Reinhardt, Andy Suprock, Bernhard Tittmann

Review of Progress in Quantitative Nondestructive Evaluation

Several Department of Energy Office of Nuclear Energy (DOE-NE) programs, such as the Fuel Cycle Research and Development (FCRD), Advanced Reactor Concepts (ARC), Light Water Reactor Sustainability, and Next Generation Nuclear Power Plants (NGNP), are investigating new fuels, materials, and inspection paradigms for advanced and existing reactors. A key objective of such programs is to understand the performance of these fuels and materials during irradiation. In DOE-NE’s FCRD program, ultrasonic based technology was identified as a key approach that should be pursued to obtain the high-fidelity, high-accuracy data required to characterize the behavior and performance of new candidate fuels ...


Results Of Using Frequency Banded Saft For Examining Three Types Of Defects, Dwight Clayton, Alan Barker, Hector Santos-Villalobos Jan 2016

Results Of Using Frequency Banded Saft For Examining Three Types Of Defects, Dwight Clayton, Alan Barker, Hector Santos-Villalobos

Review of Progress in Quantitative Nondestructive Evaluation

A multitude of concrete-based structures are typically part of a light water reactor (LWR) plant to provide the foundation, support, shielding, and containment functions. Concrete has been used in the construction of nuclear power plants (NPPs) because of three primary properties; its inexpensiveness, structural strength, and ability to shield radiation. Examples of concrete structures important to the safety of LWR plants include the containment building, spent fuel pool, and cooling towers. This use has made concrete’s long-term performance crucial for the safe operation of commercial NPPs. Extending reactor life to 60 years and beyond will likely increase susceptibility and ...


Crack Detection And Localization Inweld Structure Using The Topological Energy Method, Emma Lubeigt, Serge Mensah, Jean-François Chaix, Sandrine Rakotonarivo, Gilles Gobillot, François Baqué Jan 2016

Crack Detection And Localization Inweld Structure Using The Topological Energy Method, Emma Lubeigt, Serge Mensah, Jean-François Chaix, Sandrine Rakotonarivo, Gilles Gobillot, François Baqué

Review of Progress in Quantitative Nondestructive Evaluation

Due to both significant primary loads (weight, pressure) and thermal transients, important supporting structures (bedspring, deck…) subjected to thermo-mechanical fatigues require that periodical inspections are carried out in nuclear power plant.


The bedspring and the deck are complex welded structures of very restricted access; the ability to reliably detect and locate defects like cracks is therefore a difficult challenge. Ultrasonic testing is a well-recognized non-invasive technic which exhibits high characterization performances in homogeneous media (steel). However, its capabilities are hampered when operating in heterogeneous and anisotropic austenitic welds because of deviation and splitting of the ultrasonic beam.


In order to ...


Frequency Domain Reflectometry Nde For Aging Cables In Nuclear Power Plants, S. W. Glass, A. M. Jones, L. S. Fifield, T. S. Hartman Jan 2016

Frequency Domain Reflectometry Nde For Aging Cables In Nuclear Power Plants, S. W. Glass, A. M. Jones, L. S. Fifield, T. S. Hartman

Review of Progress in Quantitative Nondestructive Evaluation

Degradation of the cable jacket, electrical insulation, and other cable components of installed cables within nuclear power plants (NPPs) is known to occur as a function of age, temperature, radiation, and other environmental factors. System tests verify cable function under normal loads; however, demonstration of some cable’s ability to perform under exceptional loads associated with design-basis events is essential to assuring plant integrity. The cable’s ability to perform safely over the initial 40-year planned and licensed life has generally been demonstrated and there have been very few age-related cable failures.With greater than 1000 km of power, control ...


Feasibility Tests Of Ranging Inspection Of Sodium-Cooled Fast Reactor Using A Plate-Type Ultrasonic Waveguide Sensor, Young-Sang Joo, Hoe-Woong Kim, Sang-Jin Park, Sung-Kyun Kim, Jong-Bum Kim, Duck-Gun Park Jan 2016

Feasibility Tests Of Ranging Inspection Of Sodium-Cooled Fast Reactor Using A Plate-Type Ultrasonic Waveguide Sensor, Young-Sang Joo, Hoe-Woong Kim, Sang-Jin Park, Sung-Kyun Kim, Jong-Bum Kim, Duck-Gun Park

Review of Progress in Quantitative Nondestructive Evaluation

In the sodium-cooled fast reactor (SFR), conventional optical visual inspections cannot be applied due to the opacity of sodium coolant. An inspection technique based on the ultrasound should be employed because the opacity of sodium prevents any conventional techniques using optical devices from being applied for under-sodium viewing of SFR [1]. Recently, the 10 m long plate-type ultrasonic waveguide sensor has been developed for the under-sodium viewing of SFR [2]. In the plate-type ultrasonic waveguide sensor, an ultrasonic transducer installs above reactor head which is in a relatively cold condition, A0 mode Lamb wave is propagated in a plate waveguide ...


A Review Of Prognostics And Health Management Applications In Nuclear Power Plants, Jamie Coble, Pradeep Ramuhalli, Leonard J. Bond, J. Wesley Hines, Belle Ipadhyaya Jan 2015

A Review Of Prognostics And Health Management Applications In Nuclear Power Plants, Jamie Coble, Pradeep Ramuhalli, Leonard J. Bond, J. Wesley Hines, Belle Ipadhyaya

Center for Nondestructive Evaluation Publications

The US operating fleet of light water reactors (LWRs) is currently undergoing life extensions from the original 40-year license to 60 years of operation. In the US, 74 reactors have been approved for the first round license extension, and 19 additional applications are currently under review. Safe and economic operation of these plants beyond 60 years is now being considered in anticipation of a second round of license extensions to 80 years of operation.
Greater situational awareness of key systems, structures, and components (SSCs) can provide the technical basis for extending the life of SSCs beyond the original design life ...


Study Of A Nanoscale Water Cluster By Atomic Force Microscopy, Manhee Lee, Baekman Sung, Nicole N. Hashemi, Wonho Jhe Jan 2009

Study Of A Nanoscale Water Cluster By Atomic Force Microscopy, Manhee Lee, Baekman Sung, Nicole N. Hashemi, Wonho Jhe

Nastaran Hashemi

We present a novel method for investigating a nanometric cluster of water molecules, which includes the formation and manipulation of nanometric water, and the measurement of its mechanical properties. The atomic force microscope based on the quartz tuning-fork sensor is employed to form and manipulate the nanometric water, and the theoretical tool of amplitude-modulation atomic force microscopy is used to obtain the elasticity, viscosity and dissipation energy of it. With high vertical resolution less than [similar]0.1 nm and high force sensitivity of [similar]0.01 N m−1, this tool facilitates the stable formation and manipulation of a ...


The Dissipated Power In Atomic Force Microscopy Due To Interactions With A Capillary Fluid Layer, Nicole N. Hashemi, M.R. Paul, H. Dankowicz, W. Jhe Jan 2008

The Dissipated Power In Atomic Force Microscopy Due To Interactions With A Capillary Fluid Layer, Nicole N. Hashemi, M.R. Paul, H. Dankowicz, W. Jhe

Nastaran Hashemi

We study the power dissipated by the tip of an oscillating micron-scale cantilever as it interacts with a sample using a nonlinear model of the tip-surface force interactions that includes attractive, adhesive, repulsive, and capillary contributions. The force interactions of the model are entirely conservative and the dissipated power is due to the hysteretic nature of the interaction with the capillary fluid layer. Using numerical techniques tailored for nonlinear and discontinuous dynamical systems we compute the exact dissipated power over a range of experimentally relevant conditions. This is accomplished by computing precisely the fraction of oscillations that break the fluid ...


The Nonlinear Dynamics Of Tapping Mode Atomic Force Microscopy With Capillary Force Interactions, Nicole N. Hashemi, H. Dankowicz, M.R. Paul Jan 2008

The Nonlinear Dynamics Of Tapping Mode Atomic Force Microscopy With Capillary Force Interactions, Nicole N. Hashemi, H. Dankowicz, M.R. Paul

Nastaran Hashemi

We study the nonlinear dynamics of a tapping mode atomic force microscope with tip-surface interactions that include attractive, repulsive, and capillary force contributions using numerical techniques tailored for hybrid or discontinuous dynamical systems that include forward-time simulation with event handling and numerical pseudo-arclength continuation. We find four branches of periodic solutions that are separated by windows of complex and irregular dynamics. The branches of periodic solutions end where the cantilever comes into grazing contact with event surfaces in state space, corresponding to the onset of capillary interactions and the onset of repulsive forces associated with contact. These windows of irregular ...


An Analysis Of Effect Of Local Exhaust Ventilation On Tritium Surface Contamination In A Governmental Facility , Steven Gary Flann Jan 2006

An Analysis Of Effect Of Local Exhaust Ventilation On Tritium Surface Contamination In A Governmental Facility , Steven Gary Flann

Retrospective Theses and Dissertations

The objective of this study was to analyze the effectiveness of local exhaust ventilation on tritium surface contamination in a governmental maintenance and repair facility. Samples for this study were drawn from quarterly and suspected contamination swipes over a six year period and analyzed for tritium contamination utilizing a scintillation technique. The dependent variable selected was a measurement which determined whether tritium surface contamination was present. Three models were utilized to help determine the relationships between the independent variables ("location," "time," "swipe," and "test,") and the dependent variable (tritium surface contamination). Logistical regression was used to analyze radiation contamination. Through ...


A Statistical Model For Eddy‐Current Signals From Steam Generator Tubes, Aleksandar Dogandžić, Ping Xiang Jan 2004

A Statistical Model For Eddy‐Current Signals From Steam Generator Tubes, Aleksandar Dogandžić, Ping Xiang

Electrical and Computer Engineering Publications

We propose a model for characterizing amplitude and phase probability distributions of eddy‐current signals. The squared amplitudes and phases of the potential defect signals are modeled as independent, identically distributed (i.i.d.) random variables following gamma and von Mises distributions, respectively. We derive a maximum likelihood (ML) method for estimating the amplitude and phase distribution parameters from measurements corrupted by additive complex white Gaussian noise. Newton‐Raphson iteration is utilized to compute the ML estimates of the unknown parameters. The obtained estimates can be used for flaw detection as well as efficient feature extractors in a defect classification ...


Localized Charge Transfer In Csau·Nh3:  1h And 133cs Nuclear Magnetic Resonance, Steffen Kramer, Michael Mehring, Anja V. Mudring, Martin Jansen Jan 2003

Localized Charge Transfer In Csau·Nh3:  1h And 133cs Nuclear Magnetic Resonance, Steffen Kramer, Michael Mehring, Anja V. Mudring, Martin Jansen

Anja V. Mudring

We report results from 1H and 133Cs nuclear magnetic resonance (NMR) studies on CsAu·NH3. This compound has recently been synthesized and belongs to the family of ammoniates. The intense blue color of the material, which is not observed in the parent compounds, suggests that a charge-transfer electronic state is formed. The 1H NMR line shape and relaxation rates are found to be very similar to the corresponding properties in pure ammonia. However, the 133Cs-NMR properties of CsAu·NH3 strongly deviate from the corresponding ones in CsAu, and we show that the former can be interpreted consistently within a localized ...


Cobalt-Base Ferromagnetic Shape Memory Alloys, Corneliu M. Craciunescu, Yoichi Kishi, Marc De Graef, Thomas A. Lograsso Jul 2002

Cobalt-Base Ferromagnetic Shape Memory Alloys, Corneliu M. Craciunescu, Yoichi Kishi, Marc De Graef, Thomas A. Lograsso

Ames Laboratory Conference Papers, Posters, and Presentations

Single crystalline and polycrystalline CoxNiyGa100-(x+y), 41 < xCo< 62 and 19.3 < yNi < 32.7, Ferromagnetic Shape Memory Alloys have been produced in the range of the Heusler-type composition. Elasto-mechanical properties have been analyzed for the annealed and quenched states, respectively. The mechanical spectroscopy data show the occurrence of martensitic phase transformation with the transition range and characteristics depending on the state and the composition of the alloys. For XCo approximately equals 49 +/- 1 at percent, the Ni/Ga ratio was shown to be in direct relationship with the transition temperature range, from an Ms of -100 degrees C for Ni/Ga approximately equals (21/29) to a +150 degrees C for a Ni/Ga ratio of about (26/25). For Ga approximately equals 27 +/- 0.4 at percent, the Co/Ni ratio is in indirect relationship with the transition temperature, with an Ms of -125 degrees C for a (53/19) ratio to a +175 degrees C for a ratio of about (49/26). Optical and electron microscopy shows that a typical thermoelastic martensitic transformation occurs. The L21 Structurbericht parent phase transforms into monoclinic or orthohombic martensitic upon cooling. The formation of a Co-rich phase has been observed for alloys with lower Ga content and is considered to be one of the reasons for the difference in the transformation range for annealed and quenched alloys.


Flow Visualization And Pressure Drop For Refrigerant Phase Change And Air-Water Flow In Small Hydraulic Diameter Geometries , John Wesley Coleman Jan 2000

Flow Visualization And Pressure Drop For Refrigerant Phase Change And Air-Water Flow In Small Hydraulic Diameter Geometries , John Wesley Coleman

Retrospective Theses and Dissertations

A comprehensive study of two-phase flow mechanisms and pressure drop in horizontal small hydraulic diameter tubes was conducted. Co-current flow of air-water mixtures in four round tubes and one rectangular tube with hydraulic diameters ranging from 5.5 mm to 1.3 mm were investigated. Bubble, dispersed, elongated bubble, slug, stratified, wavy, annular-wavy, and annular flow patterns were observed. The results of this work show that diameter and surface tension effects play an important role in determining the flow patterns and transitions between them;Flow mechanisms during condensation of refrigerant R134a in small diameter round, square and rectangular tubes (0 ...


Real-Time Monitoring Of Low-Level Mixed-Waste Loading During Polyethylene Microencapsulation Using Transient Infrared Spectroscopy, Shukichi Ochiai, John F. Mcclelland, Roger W. Jones, Paul D. Kalb Jan 1999

Real-Time Monitoring Of Low-Level Mixed-Waste Loading During Polyethylene Microencapsulation Using Transient Infrared Spectroscopy, Shukichi Ochiai, John F. Mcclelland, Roger W. Jones, Paul D. Kalb

Ames Laboratory Conference Papers, Posters, and Presentations

In polyethylene microencapsulation, low-level mixed waste (LLMW) is homogenized with molten polyethylene and extruded into containers, resulting in a lighter, lower-volume waste form than cementation and grout methods produce. Additionally, the polyethylene-based waste form solidifies by cooling, with no risk of the waste interfering with cure, as may occur with cementation and grout processes. We have demonstrated real-time monitoring of the polyethylene encapsulation process stream using a noncontact device based on transient infrared spectroscopy (TIRS). TIRS can acquire mid-infrared spectra from solid or viscous liquid process streams, such as the molten, waste-loaded polyethylene stream that exits the microencapsulation extruder. The ...


Application Of Linear Superposition Methods To Within-Lattice Loading Design Optimization Of Light Water Reactor Nuclear Fuel Assemblies , Jie Zheng Jan 1999

Application Of Linear Superposition Methods To Within-Lattice Loading Design Optimization Of Light Water Reactor Nuclear Fuel Assemblies , Jie Zheng

Retrospective Theses and Dissertations

This study has developed a linear superposition model (LSM) for the speedy and accurate estimation of lattice physics parameters during within-bundle "pin-by-pin" loading optimization calculations. The LSM has been implemented into the FORMOSA-L optimization code and typical results show that the run-time requirements can be reduced by at least an order of magnitude relative to performing direct lattice-physics evaluations with the CPM-2 or CASMO-3 code. Moreover, the speedups noted include all overhead expenses associated with the direct lattice physics calculations required to construct the LSM sensitivity libraries. Additionally, it is shown that the errors generated by this technique can be ...


Evaluation Of Ect Signals Due To Sg Tube Crack With Deposit, Hiroyuki Fukutomi, Toshiyuki Takagi, Junji Tani, Junri Shimone, Yutaka Harada, Gangzhu Chen, Kenzo Miya Jan 1997

Evaluation Of Ect Signals Due To Sg Tube Crack With Deposit, Hiroyuki Fukutomi, Toshiyuki Takagi, Junji Tani, Junri Shimone, Yutaka Harada, Gangzhu Chen, Kenzo Miya

Review of Progress in Quantitative Nondestructive Evaluation

Eddy Current Testing (ECT) is used for in-service inspection of tubes in steam generators, heat exchangers and condensers in nuclear or conventional power plants as well as in chemical installations. ECT is particularly attractive because it offers both very high detectability and high scanning speeds. Direct contact with test material or a coupling medium is not necessary and the test is easily automated. For the tube inspection, the probes embedded sensor coils are usually inserted in the tubes. Therefore the detecting capability for an outer defect is low in comparison with an inner one by skin effect.