Showing papers by "Westinghouse Electric published in 2008"

Fatigue and durability of Nitinol stents

Abstract: Nitinol self-expanding stents are effective in treating peripheral artery disease, including the superficial femoral, carotid, and renal arteries. However, fracture occurrences of up to 50% have been reported in some stents after one year. These stent fractures are likely due to in vivo cyclic displacements. As such, the cyclic fatigue and durability properties of Nitinol-based endovascular stents are discussed in terms of an engineering-based experimental testing program. In this paper, the combined effects of cardiac pulsatile fatigue and stent-vessel oversizing are evaluated for application to both stents and stent subcomponents. In particular, displacement-controlled fatigue tests were performed on stent-like specimens processed from Nitinol microtubing. Fatigue data were collected with combinations of simulated oversizing conditions and pulsatile cycles that were identified by computer modeling of the stent that mimic in vivo deformation conditions. These data are analyzed with non-linear finite element computations and are illustrated with strain-life and strain-based constant-life diagrams. The utility of this approach is demonstrated in conjunction with 10 million cycle pulsatile fatigue tests of Cordis SMART Control((R)) Nitinol self-expanding stents to calculate fatigue safety factors and thereby predict in vivo fatigue resistance. These results demonstrate the non-linear constant fatigue-life response of Nitinol stents, whereby, contrary to conventional engineering materials, the fatigue life of Nitinol is observed to increase with increasing mean strain.

Modular multi-pulse transformer rectifier for use in asymmetric multi-level power converter

Abstract: In one embodiment, the present invention includes a system having multiple modular transformers each including a phase-shifted primary winding coupled to an input power source and phase-shifted secondary windings each coupled to a power cell The system further includes different phase output lines coupled to a load These lines may include first, second and third phase output lines

Effect of Surface Preparation on Intergranular Stress Corrosion Cracking of Alloy 600 in Hydrogenated Steam

Abstract: In the literature it is a common belief that electropolishing mitigates primary water stress corrosion cracking (PWSCC) because it removes superficial cold work. Here, it is shown that electropolished Alloy 600 (UNS N06600) exposed to hydrogenated steam undergoes internal Cr oxidation, whereas mechanical polishing induces external oxidation. This has implications for SCC initiation, which has been tested with different surface preparations (electropolishing and mechanical polishing) using reverse-U-bend (RUB) and C-ring samples. The results show a systematic trend that mechanically polished surfaces are more resistant to stress corrosion cracking (SCC) than electropolished surfaces. The mechanism involved in this increased resistance is thought to be related to short-circuit diffusion of Cr to the surface, which promotes external rather than internal oxidation. The role of compressive stress induced by mechanical polishing is a less-likely explanation of the observed effects. Mechanical polishing...

Microstructural Characterization of Oxides Formed on Model Zr Alloys Using Synchrotron Radiation

Abstract: To understand how alloy chemistry and microstructure impact corrosion performance, oxide layers formed at different stages of corrosion on various model zirconium alloys (Zr-xFe-yCr, Zr-xCu-yMo, for various x, y) and control materials (pure Zr, Zircaloy-4) were examined to determine their structure and the connection of such structure to corrosion kinetics and oxide stability. Microbeam synchrotron radiation diffraction and fluorescence of oxide cross sections were used to determine the oxide phases present, grain size, and orientation relationships as a function of distance from the oxide-metal interface. The results show a wide variation of corrosion behavior among the alloys, in terms of the pretransition corrosion kinetics and in terms of the oxide susceptibility to breakaway corrosion. The alloys that exhibited protective behavior at 500°C also were protective during 360°C corrosion testing. The Zr-0.4Fe-0.2Cr model ternary alloy showed protective behavior and stable oxide growth throughout the test. The results of the examination of the oxide layers with microbeam X-ray diffraction show clear differences in the structure of protective and nonprotective oxides both at the oxide-metal interface and in the bulk of the oxide layer. The nonprotective oxide interfaces show a smooth transition from metal to oxide with metal diffraction peaks disappearing as the monoclinic oxide peaks appear. In contrast, the protective oxides showed a complex structure near the oxide-metal interface, showing peaks from Zr3O suboxide and a highly oriented tetragonal oxide phase with specific orientation relationships with the monoclinic oxide and the base metal. The same interfacial structures are observed through their diffraction signals in protective oxide layers formed during both 360°C and 500°C corrosion testing. These diffraction peaks showed much higher intensities in the samples from 500°C testing. The results for the various model alloys are discussed to help elucidate the role of individual alloying elements in oxide formation and the influence of oxide microstructure on the corrosion mechanism.

Partial Regeneration In A Multi-Level Power Inverter

Abstract: In one embodiment, the present invention includes a medium voltage drive system having multiple power cells each to couple between a transformer and a load. A first subset of the power cells are configured to provide power to the load and to perform partial regeneration from the load, and a second subset of the power cells are configured to provide power to the load but not perform partial regeneration. A controller may be included in the system to simultaneously control a DC bus voltage of at least one of the first subset of the power cells, correct a power factor of the system, and provide harmonic current compensation for the system.

Electric control device

Abstract: Electric control devices are known, having a strip conductor substrate 2, on which an electric circuit 9 is arranged, comprising a plurality of electric components 11 connected to each other via strip conductors 12 of the strip conductor substrate, housing parts 3, 4 for covering the electric components on the strip conductor substrate, and at least one device connector part 6 electrically connected to the components, said part being disposed on the outside of the part of the strip conductor substrate 2 covered by the housing parts 3, 4, wherein the electric connections between the components and the device connector part are established by strip conductors 14 of the strip conductor substrate. The invention provides that furthermore at least one contact point 21, 22 is disposed for one further electric component 7, 8 on the strip conductor substrate 2 outside of the part covered by the housing parts 3, 4 and outside of the part of the strip conductor substrate 2 equipped with the device connector part 6.

Competitiveness of Small-Medium, New Generation Reactors: A Comparative Study on Capital and O&M Costs

Abstract: Smaller size reactors are going to be an important component of the worldwide nuclear renaissance. An inappropriate application of the economy of scale would label the small-medium size reactors as not economically competitive with larger plants because of capital costs ($/kWe) and O&M costs ($/kWh) that would appear to be significantly higher. However, the economy of scale applies only if the considered designs are similar, which is not the case here, since the small size allows original design solutions not accessible to large size reactors. In the paper the historical trend of capital costs vs. plant size is estimated from literature, and a reference exponent factor for the economy of scale for the light water reactor is derived. Then the paper identifies and briefly discusses the various factors which, beside size, contribute in differentiating the capital cost of smaller reactors with respect to large reactors. In this reference frame the evaluation for of the following factors is provided: · design characteristics · modular build · multiple units · accelerated learning in construction · operation, and shorter construction time. The IRIS reactor is used as the example of small modular reactor (SMR), but the analysis and conclusions are applicable to the whole spectrum of small nuclear plants. The results show that when all these factors are accounted for in a set of realistic and comparable configurations, and with the same power installed in the site, the capital costs of small and large plants installations are practically equivalent. Considering the O&M cost the paper shows how the plant size is not the only and fundamental cost driver. In fact there is a range of other factors (e.g. location, regulatory issues, capacity factor, plant obsolescence and number of reactors on a site) able to influence the annual O&M cost for a specific plant. The paper provides a preliminary evaluation of these factors by historical analysis of reactors built in the United States, concluding, also in this case, that when all the factors are considered the difference between the average cost ($/KWh) of Large Size vs. SMR is about 20% less than would be expected.

p-Process simulations with a modified reaction library

Abstract: We have performed p-process simulations with the most recent stellar (n, gamma) cross sections from the Karlsruhe Astrophysical Database of Nucleosynthesis in Stars project (version v0.2, http://nuclear-astrophysics.fzk.de/kadonis). The simulations were carried out with a parametrized supernova type II shock front model (`gamma-process`) of a 25 solar mass star and compared to recently published results. A decrease in the normalized overproduction factor could be attributed to lower cross sections of a significant fraction of seed nuclei located in Bi and Pb regions around the N = 126 shell closure.

Circulation and Stream Plume Modeling in Conesus Lake

Abstract: A three-dimensional hydrodynamic model that includes the effect of drag from macrophytes was applied to Conesus Lake to study the seasonal circulation and thermal structure during spring and early summer. Local weather conditions and stream flow data were used to drive the model. The drag coefficient for macrophytes was calculated as a function of leaf density. In general, the model results show good agreements with the observations, including vertical temperature profiles measured at two locations and average surface temperature derived from calibrated thermal imagery for large-scale simulations of the entire lake. Additional high-resolution simulations were carried out to understand water circulation and transport of sediment and model-generated tracer during hydrometeorological events at stream mouths for two experimental sites. The model results show that the plume development at stream mouths during storm events in Conesus Lake are site-dependent and may either be current- or wind-driven. The results also show a significant effect from the presence of macrophytes on sediment deposition near stream mouths.

System, method, and computer software code for providing an auxiliary communication path when a primary communication path is unavailable

Abstract: A method for communicating on a train that has at least two locomotives, the method including determining when a primary communication path ceases to be available for a specific subsystem of the train, identifying at least one auxiliary communication path to transmit information for the specific subsystem, configuring a message for the specific subsystem which complies with a message format of the at least one auxiliary communication path, and transmitting the message on the at least one auxiliary communication path. A system and a computer software code are further disclosed for providing a communication system for a powered system.

ZIRLO TM Cladding Improvement

Abstract: Improvements to fuel design have been made in recent years to meet the challenges of increases in fuel duty in terms of linear power and operating temperature. Improved cladding material is one of these design improvements. Specifically, Westinghouse has developed an improved version of ZIRLOTM called Optimized ZIRLO and denoted as OPT ZIRLO. The Sn level in this improved material is reduced from the nominal standard previous level of about 1 % to a range of 0.6 % to 0.8 %. The reduced Sn level has been optimized to produce a higher corrosion resistance and provide adequate in-reactor creep resistance. Out-reactor diameter creep tests have shown that decreasing Sn increases out-reactor creep, suggesting that decreasing Sn may also increase in-reactor creep. An in-reactor testing program in the Vogtle Unit 2 pressurized water reactor (PWR) was performed to confirm the predicted in-reactor behavior. The test samples were suspended as segmented rods inside fuel assembly thimble tubes. In-reactor diameter creep data confirmed that decreasing Sn increases in-reactor creep. As a result of the correlation between in-reactor and out-reactor creep, an extensive out-reactor diameter creep program was performed in order to develop methods to fabricate OPT ZIRLO with the same in-reactor creep properties as the currently used stress-relief annealed standard ZIRLO (denoted as SRA STD ZIRLO). The level of in-reactor diameter creep of SRA STD ZIRLO was achieved for OPT ZIRLO by two methods. One method involved changing the final microstructure from SRA to partially recrystallized (PRXA). The other method kept the final microstructure as SRA and changed the tube reduction sequence to decrease the final tube area reduction. In order to develop these methods, a series of material variation tests was performed. Some of the material variations included different final heat treatments, different tube reduction sequences, and different pre-charged hydrogen levels. These tests were performed for both out-reactor and in-reactor. In addition, the out-reactor and in-reactor creep were observed to directly correlate for OPT ZIRLO material fabricated with different final anneal temperatures. Thus, out-reactor creep may be used to predict in-reactor creep properties for different final anneal temperatures. These results show that fabrication changes may be used to control in-reactor creep. In this study, fabrication changes were used to compensate for the reduction in in-reactor creep strength associated with lower tin content in OPT ZIRLO.

Stator insulation system evaluation and improvement for medium voltage adjustable speed drive applications

Abstract: In the last decade, industries have refined motor insulation systems to be more suitable for low voltage (LV) adjustable speed drive (ASD) applications. Furthermore, recent advances in power electronics and control systems have significantly increased the use of medium voltage (MV) ASD on motors. However, the challenge for reliability and service life has become more critical since many MV ASD fed motor systems are often associated with much larger and more critical process controls as compared with LV ASD fed motor systems. Thus far, only limited research has been conducted to evaluate and further develop medium voltage ASD fed motor insulation systems. IEC TC 2 WG 27 experts have spent nearly 5 years developing guidelines for qualifying insulation systems that are used for ASD fed motors (IEC TC 60034-18-42). To support the frame work of this technical guideline development, a series of research studies have been conducted. In this report, partial results of these studies will be presented. The focus of this research was to evaluate the impacts of MV ASD on all insulation components in motor stator windings. Information gathered by this project provides a better understanding of the aging processes generated from MV drives on the insulation system, and helps with the improvement of insulation system designs.

Microarray-based whole-genome hybridization as a tool for determining procaryotic species relatedness.

Abstract: The definition and delineation of microbial species are of great importance and challenge due to the extent of evolution and diversity. Whole-genome DNA-DNA hybridization is the cornerstone for defining procaryotic species relatedness, but obtaining pairwise DNA-DNA reassociation values for a comprehensive phylogenetic analysis of procaryotes is tedious and time consuming. A previously described microarray format containing whole-genomic DNA (the community genome array or CGA) was rigorously evaluated as a high-throughput alternative to the traditional DNA-DNA reassociation approach for delineating procaryotic species relationships. DNA similarities for multiple bacterial strains obtained with the CGA-based hybridization were comparable to those obtained with various traditional whole-genome hybridization methods (r=0.87, P<0.01). Significant linear relationships were also observed between the CGA-based genome similarities and those derived from small subunit (SSU) rRNA gene sequences (r=0.79, P<0.0001), gyrB sequences (r=0.95, P<0.0001) or REP- and BOX-PCR fingerprinting profiles (r=0.82, P<0.0001). The CGA hybridization-revealed species relationships in several representative genera, including Pseudomonas, Azoarcus and Shewanella, were largely congruent with previous classifications based on various conventional whole-genome DNA-DNA reassociation, SSU rRNA and/or gyrB analyses. These results suggest that CGA-based DNA-DNA hybridization could serve as a powerful, high-throughput format for determining species relatedness among microorganisms.

Development of radiation detectors based on semi-insulating silicon carbide

Abstract: Fast-neutron detectors based on high-purity semi-insulating 4H silicon carbide (SiC) semiconductor have been fabricated and tested. The response characteristics of these detectors have been compared with those of epitaxial 4H-SiC Schottky diode detectors. The charge collection efficiency has been tested using alpha particles and the fast-neutron response has been tested with 14-MeV and 2.5-MeV neutrons. Over the applied voltage range tested, the charge collection efficiency for alpha particles is generally lower for the semi-insulating SiC detectors, and the fast-neutron detection efficiencies are also lower. Both the lower charge collection efficiency and the lower fast-neutron detection efficiencies are primarily caused by charge recombination in combination with the low electric fields across the thicker semi-insulating SiC detectors and the inability of the detector packaging to adequately withstand high voltages. Semiinsulating SiC detectors provide a viable alternative to epitaxial SiC diode detectors for fast-neutron detection and methods to improve the performance of semi-insulating SiC detectors are proposed.

Back Panel for Video Display Device Including Replaceable Slide-Out Electronic Components

Abstract: A back panel for a display device, such as a flat-panel television or computer monitor, which is thin around the edges and houses all electronics in a “center housing” near the vertical center of the back of the display and which houses its electronics and power supply on removable circuit boards. The back panel provides novel heat-dissipation, arranges electronics to save space and simplify repair, forces the center of gravity forward allowing the display to be set closer to a wall, and provides less interference and signal degradation than the prior art. Additionally, the removable electronics and power supply provide greater ease of repair than the prior art.

Moore's Law today

Abstract: The article discusses the progress of integrated electronics in terms of Gordon Moore's observation that the number of components on a single piece of silicon had doubled every year since the invention. This observation has become known as Moore's law. The contributions of device miniaturization and chip size to the increasing content of a chip were also discussed. The number of devices on a chip was found to increase faster than the chip area per pixel area.

Test Results for Energy Savings

Abstract: This article deals with the impact of different lubrication oils on electric motor energy consumption. Lubrication, and the analysis thereof is becoming a major field in the reliability world. All the samples of oil taken from the bearings machines, finds signs of existing or soon-to-come bearing damage and plan accordingly to reduce harmful downtime. Testing was conducted with the test motor on a motor test standard with seven ISO grade 68 lubrication oils over a two-day period.

Silicon carbide devices for radiation hard applications

Abstract: Silicon carbide has long been recognized as a favorable material for applications at high temperatures and in radiation environments, but device development has been hindered by lack of adequate substrates This paper reviews the current Westinghouse material development effort aimed at the growth of high quality 6H boules and describes 6H SiC devices fabricated on Westinghouse substrates MESFET and MOSFET transistors were made in a microwave power design layout The MESFET and MOSFET transistors were subjected to a total gamma irradiation of 1 megaGray (100 megarad) and exhibited threshold voltage shifts of about 04 and 12 Volts respectively with little change in bulk material parameters

IRIS safety-by-design™ and its implication to lessen emergency planning requirements

Abstract: International Reactor Innovative and Secure (IRIS) is an integral configuration pressurised light water reactor that has been in development since late 1999 by an international consortium. Its design and safety characteristics have been amply reported. In this paper the safety-by-design? IRIS philosophy is reviewed to show how the projected safety performance (most accidents either eliminated or inherently mitigated, Core Damage Frequency (CDF) due to internal events of the order of 10−8 events/year) exceeds the current norm of nuclear reactors. The IRIS project plans to use this enhanced safety response to explore the possibility of lessening, or even eliminating, the off-site emergency planning requirement. A review is given of previous attempts to attain this relaxation of licensing regulations and of current goals for advanced reactors. Finally, the proposed methodology is outlined. It consists of a combined deterministic and probabilistic approach, including a review of the defence in-depth, and a risk informed analysis of a wide spectrum of accidents, rather than an evaluation limited to a few design-based accidents.

MEFISTO: A Mechanistic Tool for the Prediction of Critical Power in BWR Fuel Assemblies

Abstract: Westinghouse is currently developing the MEFISTO code with the main goal to achieve fast, robust, practical and reliable prediction of steady-state dryout Critical Power in Boiling Water Reactor (BWR) fuel bundle based on a mechanistic approach To achieve this goal, the code resolves the multi-film mass balance equations at the sub-channel level within the annular flow region while relying on a simple two-field (liquid/steam) sub-channel solution to provide the cross-flow information The MEFISTO code can hence provide detailed solution to the multi-film flow in BWR fuel bundle while enhancing flexibility and reducing the computer time by an order of magnitude as compared to standard three-field subchannel analysis Models for the numerical computation of the sub-channel multi-film flowrate distributions, including the treatment of cross-flows, part-length rods and spacers grids are presented in this paper The MEFISTO code is then applied to dryout prediction in BWR fuel bundle using VIPRE-W as a two-field sub-channel driver code (based on a fast and robust four-equation model) The dryout power is numerically predicted by iterating on the bundle power so that the minimum film flowrate in the bundle reaches the dryout criteria Dryout predicted powers (including trends with flow, pressure, inlet subcooling and power distribution) and predicted dryout locations are compared to experimental results, using a large Westinghouse SVEA-96 dryout database, and are shown to yield excellent results© 2008 ASME

Insights into supporting complex systems under conditions of obsolescence

Abstract: Maintaining and supporting complex systems within a developing world context has many challenges including dealing with systems that are being operated beyond their designed life or where obsolescence is a major concern. Current methodologies to develop an integrated logistics support system (ILSS) are based on assumptions that are not valid in all cases, and a more robust framework with grounded design rules is required. The approach followed in developing the grounded technological rules was by deconstructing the available ILSS and related literature six case studies into the a framework. After analysis of this qualitative work, a third phase was added on where a questionnaire was used to explore the key areas of concern. Some of the insights regarding obsolete and beyond life complex systems were found to be: the effect of obsolescence is significantly wider than the obsolescence and retirement element of the existing frameworks; obsolescence planning must be done on reliability data for the specific operating environment, it is essential to understand technological changes and scan continuously for the impact on system or component obsolescence and that a risk based approach is essential to develop a obsolescence plan as part of the ILSS.

Compositions and methods for treating parkinson's disease and related disorders

Abstract: The present disclosure relates generally to methods and compositions for treating symptoms of Parkinson's disease and/or other movement disorders. More particularly, the present disclosure describes a method for treating symptoms of Parkinson's disease and related disorders by administering a composition comprising one or more of the following active agents; estradiol, estriol, testosterone, and 19-nortestosterone. In addition, the compositions of the present invention can be used for enhancing or optimizing the effectiveness of neural stimulation in treating the symptoms of movement disorders such as Parkinson's disease.

Human Factors and the Nuclear Renaissance

Abstract: Following the Three Mile Island incident and the Chernobyl accident, there was a general decline in public acceptance of nuclear power plants. Consequently, there was a heavy push to ensure the safety of existing plants coupled with a large-scale decline in the development of new plants. This situation has posed unique challenges to human factors within the nuclear industry. The emphasis of research came in the form of ensuring the safety of as-built systems. This approach clashed with broader human factors work, which used a variety of innovative approaches to design novel or incrementally improved interfaces. The situation is changing now. As current plants near the end of their operational life, there is an urgent need to develop new plants and modernize aging plants to sustain current energy production levels and, in many countries, to meet growing power demands. The resurgence of interest in nuclear energy has been called the “nuclear renaissance.” The challenge for human factors is now to go beyond as-built safety requirements and provide innovative interface concepts that maximize human performance in new plants. The purpose of this panel is to bring together established and new human factors professionals in nuclear energy to discuss the opportunities and challenges for research, practice, and regulation of this nuclear renaissance.