Showing papers by "Westinghouse Electric published in 2011"

Short-Circuit Analysis of Permanent-Magnet Generators

Abstract: Permanent-magnet generators (PMGs) have rapidly become important in renewable energy systems, portable and standby generating systems, and in many new applications in industrial, utility, aerospace, and automotive sectors. While there has been some discussion of “fault tolerance” and fault testing of an 8-MW machine has recently been reported [1], understanding the behavior of faulted PMGs remains far from complete. This paper addresses the important case of the sudden short circuit applied to large PMG machines. It explains key differences in short-circuit behavior between the PMG and wound-field generator. The subtransient reactances and time constants of the PMG are calculated by both analytical and finite-element methods and applied to the classical circuit-theory simulation of the short-circuit fault. The finite-element method is also used to assess in detail the risk of loss of magnetization in the magnets. The complexity of the transient magnetic field requires transient nonlinear circuit-coupled finite-element analysis in three dimensions with voltage-source excitation. This paper concludes with a review of the methods of calculation and a discussion of implications for future design and application of the PMG, including factors relevant to the application of standard tests and specifications.

Pressurized water reactor fuel crud and corrosion modeling

Abstract: Pressurized water reactors circulate high-temperature water that slowly corrodes Inconel and stainless steel system surfaces, and the nickel/iron based corrosion products deposit in regions of the fuel where sub-cooled nucleate boiling occurs. The deposited corrosion products, called ‘crud’, can have an adverse impact on fuel performance. Boron can concentrate within the crud in the boiling regions of the fuel leading to a phenomenon known as axial offset anomaly (AOA). In rare cases, fuel clad integrity can be compromised because of crud-induced localized corrosion (CILC) of the zirconium-based alloy. Westinghouse and the Electric Power Research Institute have committed to understanding the crud transport process and develop a risk assessment software tool called boron-induced offset anomaly (BOA) to avoid AOA and CILC. This paper reviews the history of the BOA model development and new efforts to develop a micro-scale model called MAMBA for use in the Consortium for Advanced Light Water Reactor Simulation (CASL) program.

Studies regarding corrosion mechanisms in zirconium alloys

Abstract: Understanding the key corrosion mechanisms in a light water reactor primary water environment is critical to developing and exploiting improved zirconium alloy fuel cladding. In this paper, we report recent research highlights from a new collaborative research programme involving 3 U.K. universities and 5 partners from the nuclear industry. A major part of our strategy is to use the most advanced analytical tools to characterise the oxide and metal/oxide interface microstructure, residual stresses, as well as the transport properties of the oxide. These techniques include three-dimensional atom probe (3DAP), advanced transmission electron microscopy (TEM), synchrotron X-ray diffraction, Raman spectroscopy, and in situ electro-impedance spectroscopy. Synchrotron X-ray studies have enabled the characterisation of stresses, tetragonal phase fraction, and texture in the oxide as well as the stresses in the metal substrate. It was found that in the thick oxide (here, Optimized-ZIRLO, a trademark of the Westinghouse Electric Company, tested at 415°C in steam) a significant stress profile can be observed, which cannot be explained by metal substrate creep alone but that local delamination of the oxide layers due to crack formation must also play an important role. It was also found that the oxide stresses in the monoclinic and tetragonal phases grown on Zircaloy-4 (autoclave testing at 360°C) first relax during the pre-transition stage. Just before transition, the compressive stress in the monoclinic phase suddenly rises, which is interpreted as indirect evidence of significant tetragonal to monoclinic phase transformation taking place at this stage. TEM studies of pre- and post-transition oxides grown on ZIRLO, a trademark of the Westinghouse Electric Company, have used Fresnel contrast imaging to identify nano-sized pores along the columnar grain boundaries that form a network interconnected once the material goes through transition. The development of porosity during transition was further confirmed by in situ electrochemical impedance spectroscopy (EIS) studies. 3DAP analysis was used to identify a ZrO sub-oxide layer at the metal/oxide interface and to establish its three-dimensional morphology. It was possible to demonstrate that this sub-oxide structure develops with time and changes dramatically around transition. This observation was further confirmed by in situ EIS studies, which also suggest thinning of the sub-oxide/barrier layer around transition. Finally, 3DAP analysis was used to characterise segregation of alloying elements near the metal/oxide interface and to establish that the corroding metal near the interface (in this case ZIRLO) after 100 days at 360°C displays a substantially different chemistry and microstructure compared to the base alloy with Fe segregating to the Zr/ZrO interface.

A review of electrical winding failures in wind turbine generators

Abstract: A quantitative review of the failure modes of over 1200 wind turbine generators repaired or replaced since 2005 has uncovered that fewer that half of the failures were electrical in nature and most of those were due to mechanical failures of the insulation support structure. In this paper, we will discuss briefly the overall failures and, in more depth, the nature of the electrical failures. Many of the failures appear to be of a serial nature due to inadequate original design of the machine and/or the insulation system. Some possible suggestions will be offered regarding repairs after catastrophic failure to help insure that the same type of failure will be less likely to repeat during the projected life of the turbine. These generators are exposed, at least in some part, to the typical voltage irregularities and mechanical stresses of any machine that operates 100 meters in the atmosphere in a wide variety of weathers. However, they are also sometimes affected by poor power quality from the IGBT based convertors used in most turbines. These failures could result from voltage stresses created by the convertor in the turbine or from neighboring turbines or, as has been suggested, even from neighboring wind parks. Defining actual root causes is therefore very difficult, but the immediate causes within the generator will be reviewed. Statistical information from other industries will also be used as a comparison to the relatively short experience of wind energy equipment. Where proper maintenance and mechanical analytical predictive techniques can drive major improvements in the mechanical life of the generators, the electrical failures are more difficult to identify before failure.

Atomic Scale Modeling of Point Defects in Zirconium Diboride

Abstract: Simulations using density functional theory were carried out to investigate the defect properties of zirconium diboride (ZrB2) and also the solution and diffusion of He and Li. Schottky and Frenkel intrinsic defect processes were all high energy as were mechanisms giving rise to nonstoichiometry; this has implications for high-temperature performance. Li and He species, formed by the transmutation of a 10B, should therefore mostly be accommodated at the resulting vacant B sites or interstitial sites. Because Li is considerably more stable at the vacant B sites, He will be accommodated interstitially. Furthermore, He was found to diffuse as an interstitial species through the lattice with a low activation energy. This would be consistent with He being lost from the ZrB2 but with Li being retained to a much greater extent.

Impact of thermomechanical texture on the superelastic response of Nitinol implants.

Abstract: The phenomenon of superelasticity in near-equiatomic NiTi, which originates from a first-order martensitic phase transition, is exploited in an increasing number of biomedical devices, most importantly endovascular stents. These stents are often manufactured from microtubing, which is shown to be highly textured crystallographically. Synchrotron X-ray microdiffraction provided microstructural, phase, and strain analysis from Nitinol tube sections that were deformed in situ along longitudinal, circumferential, and transverse orientations. We show that the large variation in the superelastic response of NiTi in these three tube directions is strongly influenced by the path that the martensitic transformation follows through the microstructure. Specifically, in severely worked NiTi, bands of 〈100〉 grains occur whose orientation deviates markedly from the surrounding matrix; these bands have an unusually large impact on the initiation and the propagation of martensite, and hence on the mechanical response. Understanding the impact of these local microstructural effects on global mechanical response, as shown here, leads to a much fuller understanding of the causes of deviation of the mechanical response from predictions and unforeseen fracture in NiTi biomedical devices.

Effects of Secondary Phase Particle Dissolution on the In-Reactor Performance of BWR Cladding

Abstract: Although the complete mechanisms are not yet fully understood, it is well established that the secondary phase particle (SPP) size distribution and chemical composition have a crucial affects in the reactor corrosion rate and hydrogen uptake in boiling water reactor (BWR) cladding. To further study these effects, different selected fuel rod assemblies with standard LK3 cladding materials that have been irradiated in KernKraftwerk Leibstadt (KKL) for three, five, six, seven, and nine annual cycles were investigated using transmission electron microscopy (TEM). TEM analysis of the samples showed that the average size of SPPs increases as the small SPPs are dissolved during irradiation. After three cycles the Fe–Cr bearing SPPs have been identified as completely amorphous over the whole range of examined samples and the Fe–Ni bearing SPPs remained crystalline. The EDX analyses of several Fe–Ni bearing precipitates show that the Fe/Ni ratio stays more or less constant for the irradiated material at 1.5 to 1.6 and drops to about 1 after fast fluence of 17.9×1021 n/cm2 (>1 MeV) for nine cycles sample. Results from this study confirms that the increased oxide thickness, the higher hydrogen content, and the accelerated growth of the rods at rod average burnup of 78 MWd/kgU goes along with a change in the appearance of SPPs by TEM.

CASL virtual reactor predictive simulation: Grid-to-Rod Fretting wear

Abstract: Grid-to-Rod Fretting (GTRF) wear is currently one of the main causes of fuel rod leaking in pressurized water reactors. The Consortium for Advanced Simulation of Light Water Reactors (CASL) has identified GTRF as one of the Challenge Problems that drive the requirement for the development and application of a modeling and simulation computational environment for predictive simulation of light water reactors. This paper presents fretting wear simulation methodology currently employed by Westinghouse, a CASL industrial partner, to address GTRF. The required advancements in the computational and materials science modeling areas to develop a predictive simulation environment by CASL to address GTRF are outlined.

Stator Design for a 1000 kW HTSC Motor With Air-gap Winding

Abstract: An air-gap winding (air-core) stator for a 1000 kW high temperature superconducting synchronous motor is designed by the Global R&D Center, TECO-Westinghouse Motor Company. This motor uses HTSC wire in the rotor field coils and Litz-wire cable in the stator coils. The rotor's cryogenic system cools the superconducting field coils to low temperature. Stator winding and back iron both are in a `warm stator' state. The stator coil chooses Roebel type Litz-wire with to eliminate the harmonics, cogging torque caused by slot opening, and to reduce vibration/noise. A quick algorithm is developed to design the stator. Electromagnetic and mechanical analyses are based on 3D FEA and thermal analysis is based on 2D FEA. Manufacture techniques for Litz wires are being developed, e.g., coil winding, crimping, testing and installation. The stator coil is in the manufacturing stage currently, and the complete machine will be tested by the end of 2010.

Fuel element storage and cooling configuration

Abstract: A fuel element storage and cooling configuration includes a fuel element storage pool and a cooling system having at least one first heat exchanger disposed in the fuel element storage pool and at least one second heat exchanger disposed in a heat sink and located at a distance therefrom, above a highest point of the first heat exchanger. The two heat exchangers are connected, using a pipe system, to form a closed circuit, which is at least partially filled with a flowable coolant. If the temperature of the first heat exchanger is increased with respect to the second heat exchanger, natural circulation of the coolant, and thus heat transport from the fuel element storage pool to the heat sink, is ensured without a pump apparatus.

An Overview of the Westinghouse Small Modular Reactor

Abstract: The Westinghouse Small Modular Reactor (SMR) incorporates an integral pressurized water reactor (iPWR) design in which all components associated with the nuclear steam supply system are housed within one pressure vessel. The Westinghouse SMR design also utilizes many of the key features from the AP1000 ® plant, including passive safety systems. The Westinghouse SMR will be fueled by a derivative of the successful 17×17 Robust Fuel Assembly (RFA) product. An 89 assembly core with an active height of 8 feet will provide a 24 month operating cycle with a power output of 800 MWt. Derived from the AP1000 plant and adapted to operate inside the reactor pressure vessel, 37 control rod drive mechanisms provide reactor shutdown and reactivity control capabilities. Eight seal less pumps provide a nominal reactor coolant flow of 100,000 gallons per minute. An innovative evolution of a straight tube steam generator produces a saturated mixture that is delivered to a steam separating drum located outside of the containment vessel. The steam generator along with the integral pressurizer is attached to the reactor vessel with a single closure flange located near the center of gravity of the reactor assembly and is designed to be removed during refueling operations. Like the AP1000 plant, the Westinghouse SMR relies on the natural forces of gravity and natural circulation to provide core and containment cooling during accident conditions. The passive cooling systems provide sufficient heat removal for seven days without the need for offsite AC power sources. The Westinghouse SMR also includes traditional active components such as diesel generators and pumps; however these components are not required for the safe shutdown of the plant. At a diameter of 32 feet, approximately 25 of the Westinghouse SMR containment vessels can fit within the envelope of the AP1000 containment building. This compact containment will be completely submerged in water during power operation providing a heat sink for postulated accidents. For protection against external threats, the containment vessel and plant safety systems are located below ground level. At approximately one fifth the net electrical output of the AP1000 plant, the Westinghouse SMR is designed to address infrastructure challenges associated with replacing America’s aging fossil fuel plants by providing a safe, clean and reliable energy source. The challenges associated with economies of scale are offset with a compact and simplified plant design, rail shippable components and modular construction.Copyright © 2011 by ASME

Corporate Posts and Tweets: Brand Control in Web 2.0

Abstract: Social networking, through media such as Twitter and Facebook, is changing influence streams on consumer (customer) attitudes and behaviours. The direct and readily available consumer-to-consumer communication, made accessible through social networking, provides a repository of information from one's referent group, as well as an organisation's customer-facing facade. Therefore as connections among customers increase, the customers assume a higher degree of brand control at the expense of corporate marketing efforts to establish a specific brand image. This paper presents the results of interviews with four organisations that have created interactive marketing strategies built upon social networking. These companies are using social media and social networks to create online communities where they can leverage peer-to-peer network influence and use this influence to reinforce or increase a positive brand image.

HycycleS: a project on nuclear and solar hydrogen production by sulphur-based thermochemical cycles

Abstract: The European FP7 project HycycleS focuses on providing detailed solutions for the design of specific key components for sulphur-based thermochemical cycles for hydrogen production. The key components necessary for the high temperature part of those processes, the thermal decomposition of H2SO4, are a compact heat exchanger for SO3 decomposition for operation by solar and nuclear heat, a receiver-reactor for solar H2SO4 decomposition, and membranes as product separator and as promoter of the SO3 decomposition. Silicon carbide has been identified as the preferred construction material. Its stability is tested at high temperature and in a highly corrosive atmosphere. Another focus is catalyst materials for the reduction of SO3. Requirement specifications were set up as basis for design and sizing of the intended prototypes. Rigs for corrosion tests, catalyst tests and selectivity of separation membranes have been designed, built and completed. Prototypes of the mentioned components have been designed and tested.

Performance investigation and comparison of line start-up permanent magnet synchronous motor with super premium efficiency

Abstract: This paper presents the performance investigation and design technology of Line Start-up Permanent Magnet Synchronous Motor(LSPMSM) with super premium efficiency, including design consideration and evaluation for motor starting-up, key performance, advanced finite element analysis(FEA) for the design, improvement and verification, prototype build and test, design and test data comparison to Premium® Efficient Induction Motor(PEIM). To assess the design technology, LSPMSM prototype was built amended from a PEIM with the same frame, stator punching and rated output. Based on the prototype test, two novel improvement designs and analyses have been done to eliminate the noise and vibration. Additionally, the comparisons with PEIM on power factor, efficiency, frame size and active material consumption indicated the significant performance improvement and active material cost down can be achieved by LSPMSM.

Detailed Analysis of the Microstructure of the Metal/Oxide Interface Region in Zircaloy-2 after Autoclave Corrosion Testing

Abstract: Two varieties of Zircaloy-2, with different second phase particle (SPP) size distributions and different corrosion resistance, were oxidized in a steam autoclave. Transmission electron microscopy (TEM) of large thin-foil cross-sections of the oxide and the adjacent metal shows an undulating metal/oxide interface in both materials with a periodicity of slightly less than 1 μm and an amplitude of around 100 nm. The SPPs oxidize slower than the surrounding metal, and the absence of volume increase leads to void and crack formation as the SPPs become embedded in the oxide. On SPP oxidation, iron diffuses out of the particles into the surrounding oxide. A sub-oxide with an oxygen content of approximately 50 at. % and a layer thickness of about 200 nm was observed close to the metal/oxide interface. There is a 200 nm oxygen concentration gradient into the metal, from the level close to the sub-oxide of about 30 at. % down to a few atomic percent. All tin in the matrix is incorporated in the sub-oxide, and no segregation to the metal/oxide interface was found.

Providing a transformer for an inverter

Abstract: In one embodiment, a transformer is provided for coupling between a utility connection and a plurality of power cells of a drive system. The transformer may be of a horizontal arrangement and include a housing and a core configured within the housing and having multiple columns each adapted along a horizontal axis. Each column corresponds to a phase, and each phase includes a coil having primary winding and multiple secondary windings concentrically adapted about the column horizontal axis to provide an air gap between adjacent ones of the primary and secondary windings. In addition, the transformer may include a baffler adapted about the core and configured within the housing to prevent air flow at a periphery of the coils and to direct air flow through the air gaps of the coils.

Back panel for video display device

Abstract: A back panel for a display device, such as a flat-panel television or computer monitor, which is very thin around the edges and houses all electronics in a “spine” near the vertical center of the back of the display. The back panel provides novel heat-dissipation, arrangement of electronics to save space, 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.

Methodologies for testing a 2 MW permanent magnet wind turbine generator

Abstract: No known guide exists for testing commercial multi-megawatt size permanent magnet (PM) wind turbine generators. Recently, a project has been approved by IEEE to develop a trial use of a guide for testing PM machines. The first author of this paper is the Chair of the working group volunteering to develop this guide. The working group has started working on the guide and plans to present its work in future. The authors of this paper would like to share their experience on testing a 2 MW wind turbine generator with a PM rotor.

Irradiation Creep and Irradiation Stress Relaxation of 316 and 304L Stainless Steels in Thermal and Fast Neutron Spectrum Reactors

Abstract: Irradiation creep and irradiation stress relaxation data have been obtained for CW 316 SS and SA 304L SS in the Halden reactor. The measurements were performed on-line during irradiation. The irradiation creep in this thermal neutron spectrum reactor was observed to be very different than values measured in fast neutron spectrum reactors. The steady state irradiation creep rate was higher in this and other thermal neutron spectrum reactors than in fast neutron spectrum reactors. On the other hand, the transient irradiation creep component was lower in thermal neutron spectrum reactors than fast neutron spectrum reactors. Therefore, fast reactor irradiation creep data are not recommended for application to light water reactors.

A fuel channel arranged to be comprised by a fuel element for a fission reactor

Abstract: A fuel channel (5) for a fuel element (1) of a fission reactor, where the fuel element comprises an inlet (9), an outlet (11) and a plurality of elongated fuel rods (3), which fuel rods each comprises a nuclear fuel and are adapted to transfer energy to a streaming medium during operation of the fission reactor. The fuel channel comprises a casing (7) adapted to surround the fuel rods between the inlet and the outlet. The casing is adapted during operation of the fission reactor to guide the streaming medium along the fuel rods from the inlet to the outlet and be subjected to irradiation from the fuel rods. The casing is manufactured from a ceramic material.