WorldWideScience

Sample records for candidate superheater tube

  1. Fireside corrosion testing of candidate superheater tube alloys, coatings, and claddings - phase II

    Energy Technology Data Exchange (ETDEWEB)

    Blough, J.L.; Stanko, G.J. [Foster Wheeler Development Corp., Livingston, NJ (United States)

    1996-08-01

    In Phase I a variety of developmental and commercial tubing alloys and claddings were exposed to laboratory fireside corrosion testing simulating a superheater or reheater in a coal-fired boiler. Phase II (in situ testing) has exposed samples of 347, RA-8511, HR3C, 253MA, Fe{sub 3}Al + 5Cr, 310 modified, 800HT, NF 709, 690 clad, and 671 clad for over 10,000 hours to the actual operating conditions of a 250-MW coal-fired boiler. The samples were installed on an air-cooled, retractable corrosion probe, installed in the reheater cavity, and controlled to the operating metal temperatures of an existing and advanced-cycle coal-fired boiler. Samples of each alloy will be exposed for 4000, 12,000, and 16,000 hours of operation. The results will be presented for the metallurgical examination of the corrosion probe samples after 4000 hours of exposure.

  2. Fireside corrosion testing of candidate superheater tube alloys, coatings, and claddings - Phase II

    Energy Technology Data Exchange (ETDEWEB)

    Blough, J.L.; Krawchuk, M.T.; Van Weele, S.F. [Foster Wheeler Development Corp., Livingston, NJ (United States)

    1995-08-01

    A number of developmental and commercial tubing alloys and claddings have previously been exposed in Phase I to laboratory fireside corrosion testing simulating a superheater or reheater in a coal-fired boiler. This program is exposing samples of TP 347, RA-85H, HR-3C, 253MA, Fe{sub 3}Al + 5Cr, 310 modified, NF-709, 690 clad, and 671 clad, which showed good corrosion resistance from Phase 1, to the actual operating conditions of a 250-MW, coal-fired boiler. The samples were installed on air-cooled, retractable corrosion probes, installed in the reheater cavity, and are being controlled to the operating metal temperatures of an existing and advanced-cycle coal-fired boiler. The exposure will continue for 4000, 12,000, and 16,000 hours of operation. After the three exposure times, the samples will be metallurgically examined to determine the wastage rates and mode of attack. The probes were commissioned November 16, 1994. The temperatures are being recorded every 15 minutes, and the weighted average temperature calculated for each sample. Each of the alloys is being exposed to a temperature in each of two temperature bands-1150 to 1260{degrees}F and 1260 to 1325{degrees}F. After 2000 hours of exposure, one of the corrosion probes was cleaned and the wall thicknesses were ultrasonically measured. The alloy performance from the field probes will be discussed.

  3. Fireside corrosion testing of candidate superheater tube alloys, coatings, and claddings -- Phase 2 field testing

    Energy Technology Data Exchange (ETDEWEB)

    Blough, J.L.; Seitz, W.W.; Girshik, A. [Foster Wheeler Development Corp., Livingston, NJ (United States)

    1998-06-01

    In Phase 1 of this project, laboratory experiments were performed on a variety of developmental and commercial tubing alloys and claddings by exposing them to fireside corrosion tests which simulated a superheater or reheater in a coal-fired boiler. Phase 2 (in situ testing) has exposed samples of 347, RA85H, HR3C, RA253MA, Fe{sub 3}Al + 5Cr, Ta-modified 310, NF 709, 690 clad, 671 clad, and 800HT for up to approximately 16,000 hours to the actual operating conditions of a 250-MW, coal-fired boiler. The samples were installed on air-cooled, retractable corrosion probes, installed in the reheater cavity, and controlled to the operating metal temperatures of an existing and advanced-cycle, coal-fired boiler. Samples of each alloy were exposed for 4,483, 11,348, and 15,883 hours of operation. The present results are for the metallurgical examination of the corrosion probe samples after the full 15,883 hours of exposure. A previous topical report has been issued for the 4,483 hours of exposure.

  4. Fireside corrosion testing of candidate superheater tube alloys, coatings, and claddings -- Phase 2

    Energy Technology Data Exchange (ETDEWEB)

    Blough, J.L.; Seitz, W.W. [Foster Wheeler Development Corp., Livingston, NJ (United States)

    1997-12-01

    In Phase 1 a variety of developmental and commercial tubing alloys and claddings were exposed to laboratory fireside corrosion testing simulating a superheater or reheater in a coal-fired boiler. Phase 2 (in situ testing) has exposed samples of 347 RA-85H, HR3C, 253MA, Fe{sub 3}Al + 5Cr, 310 Ta modified, NF 709, 690 clad, and 671 clad for approximately 4,000, 12,000, and 16,000 hours to the actual operating conditions of a 250-MW coal-fired boiler. The samples were assembled on an air-cooled, retractable corrosion probe, the probe was installed in the reheater activity of the boiler and controlled to the operating metal temperatures of an existing and advanced-cycle coal-fired boiler. The results will be presented for the preliminary metallurgical examination of the corrosion probe samples after 16,000 hours of exposure. Continued metallurgical and interpretive analysis is still on going.

  5. EBR-II Superheater Duplex Tube Examination

    International Nuclear Information System (INIS)

    After 30 years of operation, the Experimental Breeder Reactor II (EBR-II) Superheater 710 at Argonne National Laboratory-West (now Idaho National Laboratory) was decommissioned. As part of its post-service examination, four duplex tube sections were removed and Charpy impact testing was performed to characterize the crack arresting ability of nickel-bonded tube interfaces. Scanning electron microscopy (SEM) examination was also performed to characterize and identify changes in bond material microstructure. From room temperature to 400 degrees C, all samples demonstrated ductility and crack-stopping ability similar to that exhibited by beginning-of-life samples. However, at low temperature (-5 degrees C), samples removed from the lower region of the superheater (near the sodium inlet) failed while those from the upper region (near the sodium outlet) did not. SEM analysis revealed that all the tube-tube interfaces showed evidence of iron diffusion into the nickel braze, which resulted in the formation of a multiphase diffusion structure. Yet, significant void formation was only observed in the bond layer of the tubes removed from the lower region. This may be due to a change in the crystal microstructure of one of the phases within the bond layer that occurs in the 350 to 450 degrees C temperature range, which results in a lower density and the formation of porosity. Apparently, only the samples from the higher temperature region were exposed to this transition temperature, and the resulting large voids that developed acted as stress concentrators that led to low-temperature embrittlement and failure of the Charpy impact specimens

  6. Simulasi Thermal Stress Pada Tube Superheater Package Boiler

    OpenAIRE

    Hamdani

    2013-01-01

    This project investigates the thermal stress behavior and the mechanisms of superheater tube failure with experimental method and numerical analysis. First of all the procedures for failure analysis were applied to determine the root cause of them. A visual assessment of boiler critical pressure parts was carried out, and then the failed tube is examined by nondestructive evaluation. For the numerical domain, initially the elastic solution for a superheater tube subjected to an internal press...

  7. High-Temperature Graphitization Failure of Primary Superheater Tube

    Science.gov (United States)

    Ghosh, D.; Ray, S.; Roy, H.; Mandal, N.; Shukla, A. K.

    2015-12-01

    Failure of boiler tubes is the main cause of unit outages of the plant, which further affects the reliability, availability and safety of the unit. So failure analysis of boiler tubes is absolutely essential to predict the root cause of the failure and the steps are taken for future remedial action to prevent the failure in near future. This paper investigates the probable cause/causes of failure of the primary superheater tube in a thermal power plant boiler. Visual inspection, dimensional measurement, chemical analysis, metallographic examination and hardness measurement are conducted as the part of the investigative studies. Apart from these tests, mechanical testing and fractographic analysis are also conducted as supplements. Finally, it is concluded that the superheater tube is failed due to graphitization for prolonged exposure of the tube at higher temperature.

  8. Thermomechanical CSM analysis of a superheater tube in transient state

    Science.gov (United States)

    Taler, Dawid; Madejski, Paweł

    2011-12-01

    The paper presents a thermomechanical computational solid mechanics analysis (CSM) of a pipe "double omega", used in the steam superheaters in circulating fluidized bed (CFB) boilers. The complex cross-section shape of the "double omega" tubes requires more precise analysis in order to prevent from failure as a result of the excessive temperature and thermal stresses. The results have been obtained using the finite volume method for transient state of superheater. The calculation was carried out for the section of pipe made of low-alloy steel.

  9. Non-contact Measurement of Remaining Thickness of Corroding Superheater Tubes. Phase 2

    Energy Technology Data Exchange (ETDEWEB)

    Borggreen, Kjeld; Storesund, Jan

    2007-12-15

    The Electro Magnetic Acoustic Transducer (EMAT) is a contactless thickness gauge for detection of corrosion on superheater tubes; it candidates as substitute for conventional manually operated contact UT transducers. It is the aim of the project to demonstrate the usefulness of two simple EMAT systems, Panametrics and Sonatest, for fast and reliable tube thickness inspections in difficult-to-access superheater sections. The present Phase 2 of the project involves testing of the systems on real compact superheaters in remote operation with the help of a mechanical manipulator designed and built for the purpose. The results are the following: - Both EMAT systems work well when tested in the field during handheld operation on tubes with a moderate thick layer of corrosion products and ash. The practical obtainable speed of cross-panel inspection of easily accessible panels is approximately 6 tubes per minute (6 thickness readings per minute). - The Sonatest system works well when tested in the field during remote operation on heavily corroded superheater tubes with thick ash layer. The Panametrics system was not found suitable for this type of field work. - The mechanical manipulator works well for cross-panel inspection of difficult-to-access superheater sections independent of the tube dimensions and the free space between the panels. In its present design it needs few improvements. - The practical obtainable speed of cross-panel inspection is 3 tubes per minute (3 thickness readings per minute). This speed is limited by the detection rate of the EMAT system and not by the travelling speed of the probe. - Scanning of tubes along their axis was never attempted, because the EMAT instruments were not capable of collecting data coming as a continuous stream. - It cannot be judged from visual alone and hardly from the service data, if a tube or a panel can be inspected by the magnetostrictive EMAT method or not. - The main contribution to failure of the EMAT inspection

  10. Non-contact Measurement of Remaining Thickness of Corroding Superheater Tubes. Phase 1

    Energy Technology Data Exchange (ETDEWEB)

    Borggreen, Kjeld; Storesund, Jan

    2006-10-15

    Corrosion of superheaters has become a severe problem in many biomass boilers and incineration plants. This new situation calls for frequent tube wall thickness testing of the superheaters during very short shut-downs. To meet this demand Electro Magnetic Acoustic Transducer (EMAT) candidates as substitute for conventional manually operated contact UT-transducers. The EMAT can contactlessly generate an ultrasonic wave in the interphase between the external oxide and the metal. This means that measurements can be undertaken much quicker and with a much higher coverage simultaneously, without preceding blast operations. It is the aim of the project to demonstrate the usefulness of two simple EMAT systems, Panametrics and Sonatest, for fast and reliable tube thickness inspections in difficult-to-access superheater sections. The present Phase 1 of the project involves testing of the performance of the two systems in laboratory with the following results: 1. Both instruments work well on plate, tube, and pipe samples assuming the presence of an external oxide layer formed at a temperature above approximately 400 deg C. 2. Both instruments work well on all types of ferritic and martensitic steels but not on austenitic steels. 3. Both instruments work well independent of the thickness of the active oxide layer. 4. Both instruments work well independent of tube diameter, wall thickness, and sample width. 5. Both instruments work well over a very large range of wall thicknesses. Minimum tube wall thickness is less than 1.8 mm. 6. The tolerable lift-off (free distance between transducer and tube surface) is 2.4 - 3.0 mm for Panametrics system and 3.6 - 4.8 mm for Sonatest's system. The tolerable lift-off is a measure of the thickness of ash deposits, which can be tolerated on the tube surface as well as the misplacement, which can be tolerated in case of remote tube testing. 7. The tolerable off-set between tube axis and probe axis is very large for both instruments (10

  11. Analysis of temperature and stress distribution of superheater tubes after attemperation or sootblower activation

    International Nuclear Information System (INIS)

    Highlights: • The CFD simulation was used to calculate 3D steam and tube wall temperature distributions in the platen superheater. • The CFD results can be used in design of superheaters made of tubes with complex cross-section. • The CFD analysis enables the proper selection of the steel grade. • The transient temperature and stress distributions were calculated using Finite Volume Method. • The detailed analysis prevents superheater tubes from excessive stresses during sootblower or attemperator activation. - Abstract: Superheaters are characterized by high metal temperatures due to higher steam temperature and low heat transfer coefficients on the tube inner surfaces. Superheaters have especially difficult operating conditions, particularly during attemperator and sootblower activations, when temperature and steam flow rate as well as tube wall temperature change with time. A detailed thermo-mechanical analysis of the superheater tubes makes it possible to identify the cause of premature high-temperature failures and aids greatly in the changes in tubing arrangement and improving start-up technology. This paper presents a thermal and strength analysis of a tube “double omega”, used in the steam superheaters in CFB boilers

  12. Creep behaviour of 304H stainless steel superheater tubing

    International Nuclear Information System (INIS)

    While there is considerable understanding of the high temperature behaviour of ferritic alloys, the equivalent properties of austenitic in general are less well understood. Full-size multiaxial (ERA) and miniature uniaxial isothermal, temperature and stress accelerated creep-rupture tests have been carried out on a range of 304H Superheater tubing. Results show that multiaxial an uniaxial data are in close agreement and closely match the NRM standard data for 304H. Strain mapping and surface replication of the multiaxial specimens show no apparent relationship between extent of creep damage and creep strain. Scanning electron microscopy (SEM), XRD and energy dispersive spectrometry (EDAX) analysis has shown the presence of sigma-phase at grain boundaries after creep testing. Multiaxial specimens have low rupture ductility and have creep strains approximately one-quarter that of uniaxial creep strains. 9 refs., 2 tabs., 5 figs

  13. Soft Sensor for Oxide Scales on the Steam Side of Superheater Tubes under Uneven Circumferential Load

    OpenAIRE

    Qing Wei Li; Gui Huan Yao

    2015-01-01

    A soft sensor for oxide scales on the steam side of superheater tubes of utility boiler under uneven circumferential loading is proposed for the first time. First finite volume method is employed to simulate oxide scales growth temperature on the steam side of superheater tube. Then appropriate time and spatial intervals are selected to calculate oxide scales thickness along the circumferential direction. On the basis of the oxide scale thickness, the stress of oxide scales is calculated by t...

  14. Phase Identification and Internal Stress Analysis of Steamside Oxides on Plant Exposed Superheater Tubes

    DEFF Research Database (Denmark)

    Pantleon, Karen; Montgomery, Melanie

    -exposed superheater tubes was proven in the current work; the challenges for depth-resolved phase analysis and phase-specific residual stress analysis at the inner side of the tubes with concave surface curvature are discussed. Essential differences between the steamside oxides formed on two different steels...... typically applied for superheaters, ferritic-martensitic X20CrMoV12-1 and lean austenitic stainless steel TP347H, respectively, are revealed by X-ray diffraction....

  15. Lifetime evaluation of superheater tubes exposed to steam oxidation, high temperature corrosion and creep

    Energy Technology Data Exchange (ETDEWEB)

    Henriksen, N. [Elsamprojekt A/S, Faelleskemikerne, Fredericia (Denmark); Hede Larsen, O.; Blum, R. [I/S Fynsvaerket, Faelleskemikerne, Odense (Denmark)

    1996-12-01

    Advanced fossil fired plants operating at high steam temperatures require careful design of the superheaters. The German TRD design code normally used in Denmark is not precise enough for the design of superheaters with long lifetimes. The authors have developed a computer program to be used in the evaluation of superheater tube lifetime based on input related to tube dimensions, material, pressure, steam temperature, mass flux, heat flux and estimated corrosion rates. The program is described in the paper. As far as practically feasible, the model seems to give a true picture of the reality. For superheaters exposed to high heat fluxes or low internal heat transfer coefficients as is the case for superheaters located in fluidized bed environments or radiant environments, the program has been extremely useful for evaluation of surface temperature, oxide formation and lifetime. The total uncertainty of the method is mainly influenced by the uncertainty of the determination of the corrosion rate. More precise models describing the corrosion rate as a function of tube surface temperature, fuel parameters and boiler parameters need to be developed. (au) 21 refs.

  16. Improved superheater tubing material - Ti and Nb bearing austenitic steel

    International Nuclear Information System (INIS)

    A newly developed 18 Cr-8 Ni stainless steel modified with small amounts of Ti and Nb has considerably high stress-rupture strength and is considered to be suitable for superheater material for power boilers. Data for stress-rupture and creep for long times, the strength of welded joints, the changes of characteristics due to exposure to high temperatures, etc., are presented and discussed. Some investigations after trial services indicate that the experimental data are applicable to actual applications. (author)

  17. Overheating failure of superheater suspension tubes of a captive thermal power plant boiler

    International Nuclear Information System (INIS)

    Failure of boiler tubes is the foremost cause of forced boiler outages. One of the predominant failure mechanism of boiler tubes is the stress rupture failure in the form of either short term overheating or long term overheating which are normally encountered in superheater and reheater sections working in the creep range. The strength of the boiler tube depends on the stress level as well on the temperature of exposure in the creep range. An increase in either can reduce the time to rupture. Time at the exposure temperature is an important factor based on which the failures are categorised as either short term or long term. Though there is no established time duration criteria demarcating the short or long term stress rupture failures, depending on the various manifestations on the failed samples, one can categorise the failure. This paper addresses one such stress rupture failure in the superheater section of a captive thermal power plant of a refinery. Multiple failures on the suspension coil of a superheater section was investigated for the cause of failure. Laboratory investigation of the failed sample involved visual inspection, dimensional measurements, chemical analysis of internal deposits and microstructural study. On the basis of these, the failure was attributed to deposition of trisodium phosphate carried over by the feed water into the superheater section resulting in chokage and increase in local operating hoop stresses of the tube. The ultimate failure was thus categorised as long term overheating failure. (author)

  18. Failure analysis of high temperature superheater tube (HTS) of a pulverized coal-fired power station

    OpenAIRE

    Md. Mujibur Rahman; Ahmad Kamal Kadir

    2011-01-01

    This paper presents the failure investigation of high temperature superheater (HTS) tubes.  Samples were collected from one of the coal fired power plants in Malaysia, namely, Stesen Janakuasa Sultan Azlan Shah, Manjung (Manjung Power Station).  After eight years of non-continuous services of three boilers, welded support-clips were completely separated (detached) from (HTS) tubes, which caused the wall thinning.  Collected failed samples were undergone several experimental investigations inc...

  19. Premature failure of dissimilar metal weld joint at intermediate temperature superheater tube

    OpenAIRE

    Mohammed Al Hajri; Anees U. Malik; Abdelkader Meroufel; Fahd Al-Muaili

    2015-01-01

    Dissimilar metal weld (DMW) joint between alloyed steel (AS) and stainless steel (SS) failed at one of intermediate temperature superheater (ITSH) tube in steam/power generation plant boiler. The premature failure was detected after a relatively short time of operation (8 years) where the crack propagated circumferentially from AS side through the ITSH tube. Apart from physical examination, microstructural studies based on optical microscopy, SEM and EDX analysis were performed. The results o...

  20. Stress and integrity analysis of steam superheater tubes of a high pressure boiler

    OpenAIRE

    Daniel Leite Cypriano Neves; Jansen Renato de Carvalho Seixas; Ediberto Bastos Tinoco; Adriana da Cunha Rocha; Ibrahim de Cerqueira Abud

    2004-01-01

    Sources that can lead to deterioration of steam superheater tubes of a high pressure boiler were studied by a stress analysis, focused on internal pressure and temperature experienced by the material at real operating conditions. Loss of flame control, internal deposits and unexpected peak charge are factors that generate loads above the design limit of tube materials, which can be subjected to strain, buckling, cracks and finally rupture in service. To evaluate integrity and dependability of...

  1. Super-heater tube failure due to overheating when using bagasse as fuel

    Directory of Open Access Journals (Sweden)

    John Jairo Coronado Marín

    2010-04-01

    Full Text Available A super-heater’s boiler tubes presented external longitudinal cracks. The tubes’ external surfaces presented a reddish-white layer consisting of paraffin chains: CH, functional groups: CO, NH and sulphur compounds. This brittle layer prevented heat transfer, thereby causing increased tube temperature. Creep led to failure due to long-term overheating. The steel tubes’ microstructure presented grain growth, cementite globulisation and intergranular cracks on the external surface. The foregoing observations support microstructure deterioration facilitated by the presence of unsuitable super-heater tube material when just using bagasse as fuel.

  2. Stress and integrity analysis of steam superheater tubes of a high pressure boiler

    Directory of Open Access Journals (Sweden)

    Neves Daniel Leite Cypriano

    2004-01-01

    Full Text Available Sources that can lead to deterioration of steam superheater tubes of a high pressure boiler were studied by a stress analysis, focused on internal pressure and temperature experienced by the material at real operating conditions. Loss of flame control, internal deposits and unexpected peak charge are factors that generate loads above the design limit of tube materials, which can be subjected to strain, buckling, cracks and finally rupture in service. To evaluate integrity and dependability of these components, the microstructure of selected samples along the superheater was studied by optical microscopy. Associated with this analysis, dimensional inspection, nondestructive testing, hardness measurement and deposit examination were made to determine the resultant material condition after twenty three years of operation.

  3. Operational damage of steel 12Kh1MF steam superheater tubes

    International Nuclear Information System (INIS)

    The structure and mechanical properties of steel 12Kh1MF specimens are investigated after cyclic tests under conditions simulating operational regime of steam superheater tubes. It is revealed that in thermal barocycling a decrease of steel strength and a transition from trans crystalline to intercrystalline feature take place due to precipitation of complex carbides along grain boundaries. Complex carbide formation is resulted from the appearance of free carbon of decomposed carbon-containing organic impurities in a water coolant

  4. A new method for estimating heat flux in superheater and reheater tubes

    International Nuclear Information System (INIS)

    In this paper a procedure on how to estimate the heat flux in superheater and reheater tubes utilizing the empirical formula and the finite element modeling is proposed. An iterative procedure consisting of empirical formulae and numerical simulation is used to determine heat flux as both temperature and scale thickness increase over period of time. Estimation results of the heat flux over period of time for two different design temperatures of the steam and different heat transfer parameters are presented.

  5. Structure and properties of high-temperature austenitic steels for superheater tubes

    Science.gov (United States)

    Blinov, V. M.

    2009-12-01

    The structure and properties of high-temperature austenitic steels intended for superheater tubes are analyzed. Widely used Kh18N10T (AISI 304) and Kh16N13M3 (AISI 316) steels are found not to ensure a stable austenitic structure and stable properties during long-term thermal holding under stresses. The hardening of austenitic steels by fine particles of vanadium and niobium carbides and nitrides and γ'-phase and Fe2W and Fe2Mo Laves phase intermetallics is considered. The role of Cr23C6 chromium carbides, the σ phase, and coarse precipitates of an M 3B2 phase and a boron-containing eutectic in decreasing the time to failure and the stress-rupture strength of austenitic steels is established. The mechanism of increasing the stress-rupture strength of steels by boron additions is described. The chemical compositions, mechanical properties, stress-rupture strength, and creep characteristics of Russian and foreign austenitic steels used or designed for superheater tubes intended for operation under stress conditions at temperatures above 600°C are presented. The conditions are found for increasing the strength, plasticity, and thermodeformation stability of austenite in steels intended for superheater tubes operating at 700°C under high stresses for a long time.

  6. Oxide scale exfoliation and regrowth in TP347H superheater tubes: Oxide scale exfoliation and regrowth

    Energy Technology Data Exchange (ETDEWEB)

    Sabau, A. S.; Wright, I. G.; Shingledecker, J. P.

    2012-07-23

    This paper provides an introduction to a comprehensive model being developed to predict and control oxide scale exfoliation from the steam-side of superheater and reheater tubes in steam boilers. The model deals with the main phenomena involved in scale growth and failure in steam, and incorporates major variables related to boiler design and operation. The considerations used to calculate oxide growth under the specific constrains of small diameter tubes carrying high-pressure steam and operating with large temperature gradients under temperature and pressure cycling conditions, as well as the evolution of stresses and strains in the scales, are indicated but only a cursory description is given of the details of the analytical treatments. An example is presented of calculations made with the model to predict the extent of blockage expected in a single superheater loop as a function of time and outlet steam temperature under several realistic service conditions. The results suggest that problems due to scale exfoliation would be expected early in the operating life of superheater tubes made from austenitic steel TP347H.

  7. Oxide scale exfoliation and regrowth in TP347H superheater tubes

    Energy Technology Data Exchange (ETDEWEB)

    Sabau, A.S. [Oak Ridge National Laboratory, 1, Bethel Valley Road Oak Ridge, Tennessee 37830 (United States); Wright, I.G. [WrightHT, Inc., 8967 E. 35& quot; t& quot; h Avenue, Denver, Colorado 80238 (United States); Shingledecker, J.P. [Electric Power Research Institute, 1300 West W.T. Harris Blvd., Charlotte, North Carolina 28262 (United States)

    2012-10-15

    This paper provides an introduction to a comprehensive model being developed to predict and control oxide scale exfoliation from the steam-side of superheater and reheater tubes in steam boilers. The model deals with the main phenomena involved in scale growth and failure in steam, and incorporates major variables related to boiler design and operation. The considerations used to calculate oxide growth under the specific constrains of small diameter tubes carrying high-pressure steam and operating with large temperature gradients under temperature and pressure cycling conditions, as well as the evolution of stresses and strains in the scales, are indicated but only a cursory description is given of the details of the analytical treatments. An example is presented of calculations made with the model to predict the extent of blockage expected in a single superheater loop as a function of time and outlet steam temperature under several realistic service conditions. The results suggest that problems due to scale exfoliation would be expected early in the operating life of superheater tubes made from austenitic steel TP347H. (Copyright copyright 2012 WILEY-VCH Verlag GmbH and Co. KGaA, Weinheim)

  8. Soft Sensor for Oxide Scales on the Steam Side of Superheater Tubes under Uneven Circumferential Load

    Directory of Open Access Journals (Sweden)

    Qing Wei Li

    2015-01-01

    Full Text Available A soft sensor for oxide scales on the steam side of superheater tubes of utility boiler under uneven circumferential loading is proposed for the first time. First finite volume method is employed to simulate oxide scales growth temperature on the steam side of superheater tube. Then appropriate time and spatial intervals are selected to calculate oxide scales thickness along the circumferential direction. On the basis of the oxide scale thickness, the stress of oxide scales is calculated by the finite element method. At last, the oxide scale thickness and stress sensors are established on support vector machine (SMV optimized by particle swarm optimization (PSO with time and circumferential angles as inputs and oxide scale thickness and stress as outputs. Temperature and stress calculation methods are validated by the operation data and experimental data, respectively. The soft sensor is applied to the superheater tubes of some power plant. Results show that the soft sensor can give enough accurate results for oxide scale thickness and stress in reasonable time. The forecasting model provides a convenient way for the research of the oxide scale failure.

  9. Failure Investigation of Radiant Platen Superheater Tube of Thermal Power Plant Boiler

    Science.gov (United States)

    Ghosh, D.; Ray, S.; Mandal, A.; Roy, H.

    2015-04-01

    This paper highlights a case study of typical premature failure of a radiant platen superheater tube of 210 MW thermal power plant boiler. Visual examination, dimensional measurement and chemical analysis, are conducted as part of the investigations. Apart from these, metallographic analysis and fractography are also conducted to ascertain the probable cause of failure. Finally it has been concluded that the premature failure of the super heater tube can be attributed to localized creep at high temperature. The corrective actions has also been suggested to avoid this type of failure in near future.

  10. Investigation into Cause of High Temperature Failure of Boiler Superheater Tube

    Science.gov (United States)

    Ghosh, D.; Ray, S.; Roy, H.; Shukla, A. K.

    2015-04-01

    The failure of the boiler tubes occur due to various reasons like creep, fatigue, corrosion and erosion. This paper highlights a case study of typical premature failure of a final superheater tube of 210 MW thermal power plant boiler. Visual examination, dimensional measurement, chemical analysis, oxide scale thickness measurement, microstructural examination are conducted as part of the investigations. Apart from these investigations, sulfur print, Energy Dispersive spectroscopy (EDS) and X ray diffraction analysis (XRD) are also conducted to ascertain the probable cause of failure of final super heater tube. Finally it has been concluded that the premature failure of the super heater tube can be attributed to the combination of localized high tube metal temperature and loss of metal from the outer surface due to high temperature corrosion. The corrective actions have also been suggested to avoid this type of failure in near future.

  11. Microscopical investigation of steamside oxide on X20CrMoV121 superheater tubes

    DEFF Research Database (Denmark)

    Montgomery, Melanie; Hansson, Anette Nørgaard; Jensen, Søren A.;

    2011-01-01

    X20CrMoV121 is a 12%Cr martensitic steel which has been used in power plants in Europe for many decades. Superheater tubes exposed for various durations up to 135,000 hours in power plants in Denmark at steam temperatures varying from 450 to 575°C were investigated. Light optical and scanning...... electron microscopy was used to investigate steamside oxide morphologies. At all temperatures there is a double layered oxide, however, the inner:outer oxide thickness is not always equal. At the lower steam temperature range of...

  12. The creep life of superheater and reheater tubes under varying pressure conditions in operational boilers

    International Nuclear Information System (INIS)

    The first of each manufacturer's 500 MW boilers supplied to the CEGB (Central Electricity Generating Board) have been subjected to an extensive programme of tests for performance optimization and safe operation. Around 250 thermocouples on superheater and reheater tubes have in each case been monitored as part of the exercise. The readings are corrected and used to compute creep rupture damage based on internationally agreed stress rupture data and a simple cumulative damage concept. Comparison of the design creep rupture life and the cumulative life consumed has in several applications been invaluable in influencing operating procedures and arranging tube modifications or replacements, so that loss of generation by creep rupture failure is minimized. (author)

  13. Premature failure of dissimilar metal weld joint at intermediate temperature superheater tube

    Directory of Open Access Journals (Sweden)

    Mohammed Al Hajri

    2015-04-01

    Full Text Available Dissimilar metal weld (DMW joint between alloyed steel (AS and stainless steel (SS failed at one of intermediate temperature superheater (ITSH tube in steam/power generation plant boiler. The premature failure was detected after a relatively short time of operation (8 years where the crack propagated circumferentially from AS side through the ITSH tube. Apart from physical examination, microstructural studies based on optical microscopy, SEM and EDX analysis were performed. The results of the investigation point out the limitation of Carbides precipitation at the alloyed steel/welding interface. This is synonym of creep stage I involvement in the failure of ITSH. Improper post-welding operation and bending moment are considered as root causes of the premature failure.

  14. Degradation of superheater tubes made of austenitic T321H steel after long term service

    Energy Technology Data Exchange (ETDEWEB)

    Hernas, Adam [Silesian Technical Univ., Katowice (Poland). Faculty of Material Science; Augustyniak, Boleslaw; Chmielewski, Marek [Gdansk Univ. of Technology (Poland). Mechanical Dept.; Sablik, M.J. [Applied Magnetic and Physical Modeling, LLC, San Antonio, TX (United States)

    2010-07-01

    There are presented results of complementary tests performed for the evaluation of creep damage in austenitic steel grade T321H exploited over 200,000 hours in the secondary superheater part of a power plant boiler. The following techniques have been applied: SEM microscopy, X-ray diffraction, tensile tests, hardness measurements and novel eddy current inspection. The novel eddy current inspection is proposed as a non-destructive method of estimating the creep damage stage of austenite steel boiler tubes after long-term service in power plants. We compare the results provided by the different techniques and discuss the correlations and also point out the problems which need to be addressed in order to elaborate the remaining life assessment of austenitic boiler tubes. (orig.)

  15. Can the lifetime of the superheater tubes be predicted according to the fuel analyses? Assessment from field and laboratory data

    Energy Technology Data Exchange (ETDEWEB)

    Salmenoja, K. [Kvaerner Pulping Oy, Tampere (Finland)

    1998-12-31

    Lifetime of the superheaters in different power boilers is more or less still a mystery. This is especially true in firing biomass based fuels (biofuels), such as bark, forest residues, and straw. Due to the unhomogeneous nature of the biofuels, the lifetime of the superheaters may vary from case to case. Sometimes the lifetime is significantly shorter than originally expected, sometimes no corrosion even in the hottest tubes is observed. This is one of the main reasons why the boiler operators often demand for a better predictability on the corrosion resistance of the materials to avoid unscheduled shutdowns. (orig.) 9 refs.

  16. A computational approach for thermomechanical fatigue life prediction of dissimilarly welded superheater tubes

    Energy Technology Data Exchange (ETDEWEB)

    Krishnasamy, Ram-Kumar; Seifert, Thomas; Siegele, Dieter [Fraunhofer-Institut fuer Werkstoffmechanik (IWM), Freiburg im Breisgau (Germany)

    2010-07-01

    In this paper a computational approach for fatigue life prediction of dissimilarly welded superheater tubes is presented and applied to a dissimilar weld between tubes made of the nickel base alloy Alloy617 tube and the 12% chromium steel VM12. The approach comprises the calculation of the residual stresses in the welded tubes with a multi-pass dissimilar welding simulation, the relaxation of the residual stresses in a post weld heat treatment (PWHT) simulation and the fatigue life prediction using the remaining residual stresses as initial condition. A cyclic fiscoplasticity model is used to calculate the transient stresses and strains under thermocyclic service loadings. The fatigue life is predicted with a damage parameter which is based on fracture mechanics. The adjustable parameters of the model are determined based on LCF and TMF experiments. The simulations show, that the residual stresses that remain after PWHT further relax in the first loading cycles. The predicted fatigue lives depend on the residual stresses and, thus, on the choice of the loading cycle in which the damage parameter is evaluated. It the first loading cycle, where residual stresses are still present, is considered, lower fatigue lives are predicted compared to predictions considering loading cycles with relaxed residual stresses. (orig.)

  17. Failure analysis of high temperature superheater tube (HTS of a pulverized coal-fired power station

    Directory of Open Access Journals (Sweden)

    Md. Mujibur Rahman

    2011-01-01

    Full Text Available This paper presents the failure investigation of high temperature superheater (HTS tubes.  Samples were collected from one of the coal fired power plants in Malaysia, namely, Stesen Janakuasa Sultan Azlan Shah, Manjung (Manjung Power Station.  After eight years of non-continuous services of three boilers, welded support-clips were completely separated (detached from (HTS tubes, which caused the wall thinning.  Collected failed samples were undergone several experimental investigations including visual inspection, thickness measurement, Vickers hardness testing, and microstructure evaluation.  The results revealed that some cracks were initiated at the heat-affected zone (HAZ and propagated partly throughout the weld metal. The estimation on operating temperature and operating hoop stress show indication that the specimen may experienced a hig operating temperature. Other findings confirmed that the detachment of welded support-clips from HTS tubes may also caused by dissimilar metal weld (DMW failure due to the differences in expansion properties of parent metal and weld metal.

  18. Temperature prediction method for superheater and reheater and reheater tubes of fossil power plant boiler during operation

    Energy Technology Data Exchange (ETDEWEB)

    Kim, Bum Shin; Song, Gee Wook; Yoo, Seong Yeon [Chungnam Nat' l Univ., Daejeon (Korea, Republic of)

    2012-05-15

    The superheater and reheater tubes of a heavy load fossil power plant boiler can be damaged by overheating, and therefore, the degree of overheating is assessed by measuring the oxide scale thickness inside the tube during outages. The tube temperature prediction from the oxide scale thickness measurement is necessarily accompanied by destructive tube sampling, and the result of tube temperature prediction cannot be expected to be accurate unless the selection of the overheated point is precise and the initial operation tube temperature has been obtained. In contrast, if the tube temperature is to be predicted analytically, considerable effort (to carry out the analysis of combustion, radiation, convection heat transfer, and turbulence fluid dynamics of the gas outside the tube) is required. In addition, in the case of analytical tube temperature prediction, load changes, variations in the fuel composition, and operation mode changes are hardly considered, thus impeding the continuous monitoring of the tube temperature. This paper proposes a method for the short term prediction of tube temperature; the method involves the use of boiler operation information and flow network analysis based tube heat flux. This method can help in high temperature damage monitoring when it is integrated with a practical tube damage assessment method such as the Larson Miller Parameter.

  19. 过热器炉管爆管原因分析%Analysis of Tube Bursting at Superheater

    Institute of Scientific and Technical Information of China (English)

    窦莹婷; 李君; 张峥

    2012-01-01

    The failure causes of tube bursting at superheater were analyzed by many tests and several research methods, such as macro inspection, dimensional measurement of tube perimeter change, mi-crostructure examination, mechanical testing and stress check. The results show that the tube is se-verely oxidized and overheated, which intensifies the situation of overheating operation. Inflation of the tube, thinning of the tube wall and fully pearlite spheroidized microstructure can be observed, and the strength of the material deteriorates significantly. It is concluded that the tube failure mode is overloading. At the same time, some useful suggestions such as periodic measurement of tube perime-ter and metallographic examination are proposed, which can be a reference for operation and mainte-nance.%通过宏观检查、胀粗测量、金相组织检查、室温拉伸力学性能测试及应力校核,对过热器炉管爆管原因进行了分析.结果表明:长期运行的炉管内外壁氧化严重,影响管道传热,加剧了管道过热运行情况,胀粗、减薄明显,金相组织已完全珠光体球化,使材料强度低于实际承载应力而发生过载失效.建议加强胀粗和氧化测量,并定期进行金相检查,及时发现问题,更换管道.

  20. Phase identification and internal stress analysis of steamside oxides on superheater tubes by means of X-ray diffraction

    Energy Technology Data Exchange (ETDEWEB)

    Pantleon, Karen; Montgomery, Melanie [Technical Univ. of Denmark, Lyngby (Denmark). Inst. of Manufacturing Engineering and Management

    2005-05-01

    For superheater tubes, the adherence of the inner steamside oxide is especially important as spallation of this oxide results in a) blockage of loops which cause insufficient steam flow through the superheaters and subsequently overheating and tube failure and b) spalled oxide can cause erosion of turbine blades. Oxide spallation is a serious problem for austenitic steels where the significant differences of the thermal expansion coefficients of steel and oxide cause relatively high thermal stresses. Usually, various oxides layered within the scale are suggested from microscopical observations of the morphology and/or topography of the oxide scale accompanied by the analysis of chemical elements present. Reports about the application of X-ray diffraction on the study of steamside oxide formation are very scarce in literature. If applied at all, XRD-studies are restricted to ideally flat samples oxidized under laboratory conditions, but relation to real operating conditions and the effect of the real sample geometry is missing. Within the frame of the project, steamside oxides on plant exposed components of ferritic/ martensitic X20CrMoV12-1 as well as fine- and coarse-grained austenitic TP347H were studied by means of X-ray diffraction. Depth dependent phase analysis on sample segments cut from the tubes was carried out by means of grazing incidence diffraction and, in order to obtain information from a larger depth, conventional XRD was combination with stepwise mechanical removal of the steamside oxides. After each removal step phase analysis was performed both on the segments and on the removed powders. Phase specific stress analysis was carried out on rings cut from the tube. Results show that steamside oxides on X20CrMoV12-1 consist of pure Hematite at the surface followed by a relatively thick layer of pure Magnetite. Both phases are under relatively high tensile stresses. While the phase composition of the Hematite layer appears to be the same for all

  1. Acoustic emission analysis on tensile failure of steam-side oxide scales formed on T22 alloy superheater tubes

    Science.gov (United States)

    Huang, Jun-Lin; Zhou, Ke-Yi; Wang, Xin-Meng; Tu, Yi-You; Xu, Jian-Qun

    2014-07-01

    Failure of steam-side oxide scales on boiler tubes can seriously influence the safety of coal-fired power plants. Uniaxial tensile tests employing acoustic emission (AE) monitoring were performed, in this work, to investigate the failure behavior of steam-side oxide scales on T22 alloy boiler superheater tubes. The characteristic frequency spectra of the captured AE signals were obtained by performing fast Fourier transform. Three distinct peak frequency bands, 100-170, 175-250, and 280-390 kHz, encountered in different testing stages were identified in the frequency spectra, which were confirmed to, respectively, correspond to substrate plastic deformation, oxide vertical cracking, and oxide spalling with the aid of scanning electronic microscopy observations, and can thus be used for distinguishing different oxide failure mechanisms. Finally, the critical cracking strain of the oxide scale and the interfacial shear strength of the oxide/substrate interface were estimated, which are the critical parameters urgently desired for modeling the failure behavior of steam-side oxide scales on boiler tubes of coal-fired power plants.

  2. Acoustic emission analysis on tensile failure of steam-side oxide scales formed on T22 alloy superheater tubes

    Energy Technology Data Exchange (ETDEWEB)

    Huang, Jun-Lin; Zhou, Ke-Yi, E-mail: boiler@seu.edu.cn; Xu, Jian-Qun [Key Laboratory of Energy Thermal Conversion and Control of Ministry of Education, School of Energy and Environment, Southeast University, Nanjing 210096, Jiangsu Province (China); Wang, Xin-Meng; Tu, Yi-You [School of Materials Science and Engineering, Southeast University, Nanjing 210096, Jiangsu Province (China)

    2014-07-28

    Failure of steam-side oxide scales on boiler tubes can seriously influence the safety of coal-fired power plants. Uniaxial tensile tests employing acoustic emission (AE) monitoring were performed, in this work, to investigate the failure behavior of steam-side oxide scales on T22 alloy boiler superheater tubes. The characteristic frequency spectra of the captured AE signals were obtained by performing fast Fourier transform. Three distinct peak frequency bands, 100-170, 175-250, and 280-390 kHz, encountered in different testing stages were identified in the frequency spectra, which were confirmed to, respectively, correspond to substrate plastic deformation, oxide vertical cracking, and oxide spalling with the aid of scanning electronic microscopy observations, and can thus be used for distinguishing different oxide failure mechanisms. Finally, the critical cracking strain of the oxide scale and the interfacial shear strength of the oxide/substrate interface were estimated, which are the critical parameters urgently desired for modeling the failure behavior of steam-side oxide scales on boiler tubes of coal-fired power plants.

  3. Acoustic emission analysis on tensile failure of steam-side oxide scales formed on T22 alloy superheater tubes

    International Nuclear Information System (INIS)

    Failure of steam-side oxide scales on boiler tubes can seriously influence the safety of coal-fired power plants. Uniaxial tensile tests employing acoustic emission (AE) monitoring were performed, in this work, to investigate the failure behavior of steam-side oxide scales on T22 alloy boiler superheater tubes. The characteristic frequency spectra of the captured AE signals were obtained by performing fast Fourier transform. Three distinct peak frequency bands, 100-170, 175-250, and 280-390 kHz, encountered in different testing stages were identified in the frequency spectra, which were confirmed to, respectively, correspond to substrate plastic deformation, oxide vertical cracking, and oxide spalling with the aid of scanning electronic microscopy observations, and can thus be used for distinguishing different oxide failure mechanisms. Finally, the critical cracking strain of the oxide scale and the interfacial shear strength of the oxide/substrate interface were estimated, which are the critical parameters urgently desired for modeling the failure behavior of steam-side oxide scales on boiler tubes of coal-fired power plants.

  4. Pressure tests to assess the significance of defects in boiler and superheater tubing

    International Nuclear Information System (INIS)

    Internal pressure tests on 9 per cent Cr-1 per cent Mo steel tubing containing artificial defects demonstrated that the resultant loss of strength was less than a simple calculation based on the reduced tube thickness would suggest. Bursting tests on tubes containing longitudinal defects of varying length, depth and acuity showed notch strengthening at ambient temperature and at 5500C. A flow stress concept developed for simple bursting tests was shown to apply to creep conditions at 5500C. Results of creep and short-term bursting tests show that the length as well as the depth of the defect is an important factor affecting the life of bursting strength of the tubes. Defects less than 10 per cent of the tube thickness were found to have an insignificant effect. (author)

  5. A thin-lip rupture of carbon steel superheater boiler tube

    International Nuclear Information System (INIS)

    A ruptured A 42 medium carbon steel tube was collected by the engineering department in one of our steam power stations. Inspection of ruptured tube revealed a thin - lip fracture with brownish thin layer of oxide film on inner tube surfaces. There was no evidence of pitting, the outer surfaces of the tube exhibited a general oxidized conditions. A micro section taken near the fracture surface consists of ferrite and martensite, the amount of martensite decreased as we away from the fracture surface. Presence of martensite phase in the microstructure indicates that the tube material has been overheated. An erosion corrosion mechanism in conjunction with overheated. An erosion corrosion mechanism in conjunction with overheating resulted in strength deterioration with consequent premature failure. 4 fig., 1 tab

  6. 火电厂过热器管爆管分析%Analysis of Explosion of Superheater Tube in Thermal Power Plant

    Institute of Scientific and Technical Information of China (English)

    江国栋; 唐庆顺; 洪茂林; 姚建盛

    2011-01-01

    The macro-examination of superheater tube, metallographic observation and microstructure analysis were carried out, and the mechanical properties were tested. The results show that: the main reasons for the platen superheater tube failure are the inter-action results of long-time over temperature and short-time over temperature.%对屏式过热器管进行了宏观检查、金相显微组织观察和分析以及拉伸性能测试.结果表明,该屏式过热器管失效的主要原因是长时超温与短时超温共同作用的结果.

  7. Super-heater tube failure due to overheating when using bagasse as fuel

    OpenAIRE

    John Jairo Coronado Marín

    2010-01-01

    A super-heater’s boiler tubes presented external longitudinal cracks. The tubes’ external surfaces presented a reddish-white layer consisting of paraffin chains: CH, functional groups: CO, NH and sulphur compounds. This brittle layer prevented heat transfer, thereby causing increased tube temperature. Creep led to failure due to long-term overheating. The steel tubes’ microstructure presented grain growth, cementite globulisation and intergranular cracks on the external surface. The foregoing...

  8. 二级过热器管爆管失效分析%Failure Analysis on the Tube Explosion of Two-stage Superheater

    Institute of Scientific and Technical Information of China (English)

    陈晓潇; 丛红梅; 高洪吉

    2014-01-01

    某厂锅炉二级过热器管带负荷运行25 h即发生爆管,管壁涨粗,爆裂口张开呈喇叭状。采用化学成分分析、力学性能检测和金相组织分析等检测手段,对该二级过热器管的失效原因进行了分析。结果表明,该管裂口处显微组织随变形方向被拉长,管体组织无明显变化,但钢管外表层氧化和脱碳严重,同时表面出现沿晶小裂纹,说明管壁在短时间内受到较高温的烟气冲刷,导致材料强度下降。短时间内高温过热是过热器管爆管失效的主要原因。%After running with load for 25 hours, the secondary superheater tube of boiler exploded, which made the tube thicker and the crack trumpet-shaped open. The analysis for a boiler secondary superheater tube explosion adopts detection modes of chemical component analysis, mechanical properties test and microstructure analysis. The results show that microstructure of the crack was elongated along the deformation direction, and microstructure of the tube was no significant change, but the outside surface of the tube was oxygenated and decarburized severely. Meanwhile the short crack along grain boundaries appeared in the surface. All that means the tube suffered from erosion of high temperature flue gas within a short time. High temperature superheated in a short time is the main reason for the failure of the superheater tube.

  9. Failure Analysis of Low Temperature Superheater Tube of Utility Boiler%电站锅炉低温过热器管失效分析

    Institute of Scientific and Technical Information of China (English)

    周经伟; 周荣稳

    2013-01-01

      Through making the failure analysis on low temperature superheater tube by employing the related technological means, the paper determines the cause of failure and puts preventive measures to avoid and prevent similar incidents from happening again.%  通过对低温过热器爆管,采用相关的技术手段进行失效情况分析,确定失效的原因,提出预防措施,避免和防止同类事故的再次发生。

  10. 我国700℃超超临界锅炉过热器管用高温合金选材探讨%Selection of Superalloys for Superheater Tubes of Domestic 700 ℃ A-USC Boilers

    Institute of Scientific and Technical Information of China (English)

    林富生; 谢锡善; 赵双群; 董建新

    2011-01-01

    简要介绍和比较了国内外700℃超超临界电站过热器和再热器管候选材料GH2984、Haynes 230、CCA 617、Nimonic 263、Inconel 740及其改型合金Inconel 740H的组织、持久强度和耐腐蚀性能等研究结果,对几种材料的强度、耐腐蚀性能、工艺性能和使用经济性进行了分析,并阐述了中国在发展700℃超超临界燃煤电站时锅炉用高温合金的选择.结果表明:Inconel 740H合金具有的持久强度最高、耐蚀性能最好,工艺性能和使用经济性良好,比Inconel 740合金具有更好的长期组织稳定性,它应是中国700℃超超临界锅炉过热器和再热器首选的管材;针对700℃超超临界机组用关键材料,提出了尽早开展自主研制,实现关键材料国产化的建议.%Research achievements on major candidate materials for superheater/reheater tubes of plants at home and abroad are reviewed and compared,such as the GH2984,Haynes 230,CCA 617,Nimonic 263,Inconel 740 and Inconel 740H,while their microstructure,stress rupture strength and corrosion resistance as well as their workability and economy were analyzed.A discussion is moreover carried out to the selection of superalloys for superheater/reheater tubes of domestic 700 ℃ A-USC power plants.Results show that superalloy Inconel 740H exhibits the highest stress rupture strength,strongest corrosion resistance,better workability and economy among above six alloys;its microstructure is more stable than that of Inconel 740 during long term aging,which is therefore at present believed to be most preferable for superheater/reheater tubes of domestic 700 ℃ A-USC power plants.For localization of key materials for relevant power plants,it is suggested that RD on these materials should be performed as early as possible.

  11. A Study of the Effect of Kaolin as a Fuel Oil Additive on the Corrosion Inhibition of Fireside Superheater Boiler Tubes

    Directory of Open Access Journals (Sweden)

    Alaa' Mshjel Ali

    2010-01-01

    Full Text Available The objective of the present study is to determine the effect of Kaolin as a fuel oil additive to minimize the fireside corrosion of superheater boiler tubes of ASTM designation (A213-T22 by increasing the melting point of the formed slag on the outside tubes surface, through the formation of new compounds with protective properties to the metal surface. The study included measuring corrosion rates at different temperatures with and without additive use with various periods of time, through crucible test method and weight loss technique.A mathematical model represents the relation between corrosion rate and the studied variables, is obtained using statistical regression analysis. Using this model, the best additive to ash weight ratio was specified. Then scanning electron microscopic images taken to the two treated and untreated samples with additive to study the difference in nature of slag formed on the metal surface to the two cases.

  12. 分隔屏过热器爆管原因分析%Cause Analysis of Partition Platen Superheater Tube Explosion

    Institute of Scientific and Technical Information of China (English)

    王宝臣; 付秋枫; 唐丽英; 王秋生; 李勇

    2013-01-01

    In a power generation company, partition platen superheater explosion for overheating, because the tube morphology is relatively special, and the condenser leakage happened before explosion, sodion and chloridion were exceed the standard during leakage, bring great trouble for failure analysis, but the tube explosion reason finally confirmed through the analysis of system experiment. This paper systematically analyzes the cause of the tube explosion.%  某发电公司分隔屏过热器因过热发生爆管,但爆管形貌较为特殊,且爆管前曾发生过凝汽器泄漏,泄漏期间Na+及Cl-均超标,为失效分析带来很大困扰,通过系统实验分析,最终确定爆管原因。本文系统地分析了此次爆管的原因。

  13. Failure analysis for 15CrMo superheater bent tubes%15CrMo高温过热器弯管的失效分析

    Institute of Scientific and Technical Information of China (English)

    程宏辉; 曹磊; 靳惠明; 黄新; 秦康生

    2011-01-01

    分析了75 t/h高压循环流化床锅炉用15CrMo高温过热器弯管在试运行近100h 下产生裂纹的原因结果表明,由于炉水中氯离子含量超标以及停炉期间未进行保护,导致大量空气进入炉体,在高温、弯管自身高残余应力等综合作用下产生应力腐蚀,这是导致过热器弯管失效的主要原因.%Failure analysis is performed for 15CrMo superheater bent tubes of a 75 t/h high-pressure circulating fluidized bed boiler operated for less than 100 h. The results indicate that the bent tubes are subjected to stress corrosion cracking, due to excessive chloride ion in the boiler water, the entry of air during the boiler shutdown, high temperature work environment and high residual stress in the bent tube.

  14. Failure Analysis of Platen Superheater Tube of Fuel-oil Boiler%炼厂燃油锅炉屏式过热器管失效分析

    Institute of Scientific and Technical Information of China (English)

    莫烨强; 罗建成; 孙亮; 侯艳宏

    2014-01-01

    采用宏观观察、金相观察、扫描电子显微分析、成分分析等分析方法,对燃油锅炉屏式过热器发生开裂失效原因进行了分析研究。结果表明:该管长期在高温下运行产生了蠕变现象;珠光体组织出现严重的球化现象,大量碳化物呈链状沿晶界析出;过热器管道内壁存在约371.55μm厚度的氧化层。因此,管束长期局部过热服役,致使金相组织发生改变,大大降低了材料的力学性能,从而发生蠕变开裂现象。%The failure reasons of a platen superheater tube of a fuel-oil boiler were studied by macroscopic observation, metallographic analysis, scanning electron microscopy ( SEM ) and energy dispersive spectroscopy ( EDS ) . The result of macroscopic observation shows that creep cracking happened to the tube after working for a long time at high temperature. The result of metallographic analysis shows that the carbide precipitated at grain boundaries. The result of scanning electron microscopy( SEM) and energy dispersive spectroscopy( EDS) show that a oxidation layer formed on the inside of the tube. The thickness of the oxidation layer was 371. 55μm. It can be concluded that long-term local overheating occurred to the tube during working, leading to microstructure change and reducing the mechanical properties of the material.

  15. Evaluation of Hot corrosion of type 316 stainless steel superheater tubes under some highly aggressive salt deposits

    International Nuclear Information System (INIS)

    The corrosion of type 316 stainless steel tubes by the sprayed Na CI+Na2 S O4 solution was investigated at 600 degree C. The role of V2 O5 present in the Na CI+NaS O4 spraying solution, and the effect of addition of Ca(OH)2 to the previous solution on the hot corrosion process were also investigated. Optical microscopy and SEM were used to determine tube wastage morphology. EDAX analysis and mapping techniques were used to investigate the interdiffusion of aggressive ions in both tube metal and scale. It was found that the tube metal wastage corroded in the sprayed solution (Na CI + Na2 S O4 + V2 O5) was greater than that in the sprayed solution (Na CI + Na2 S O4). The addition of Ca(OH)2 to the spraying solution decreased noticeably the wastage of the tube metal. 11 figs

  16. Superheater Corrosion In Biomass Boilers: Today's Science and Technology

    Energy Technology Data Exchange (ETDEWEB)

    Sharp, William (Sandy) [SharpConsultant

    2011-12-01

    This report broadens a previous review of published literature on corrosion of recovery boiler superheater tube materials to consider the performance of candidate materials at temperatures near the deposit melting temperature in advanced boilers firing coal, wood-based fuels, and waste materials as well as in gas turbine environments. Discussions of corrosion mechanisms focus on the reactions in fly ash deposits and combustion gases that can give corrosive materials access to the surface of a superheater tube. Setting the steam temperature of a biomass boiler is a compromise between wasting fuel energy, risking pluggage that will shut the unit down, and creating conditions that will cause rapid corrosion on the superheater tubes and replacement expenses. The most important corrosive species in biomass superheater corrosion are chlorine compounds and the most corrosion resistant alloys are typically FeCrNi alloys containing 20-28% Cr. Although most of these materials contain many other additional additions, there is no coherent theory of the alloying required to resist the combination of high temperature salt deposits and flue gases that are found in biomass boiler superheaters that may cause degradation of superheater tubes. After depletion of chromium by chromate formation or chromic acid volatilization exceeds a critical amount, the protective scale gives way to a thick layer of Fe{sub 2}O{sub 3} over an unprotective (FeCrNi){sub 3}O{sub 4} spinel. This oxide is not protective and can be penetrated by chlorine species that cause further acceleration of the corrosion rate by a mechanism called active oxidation. Active oxidation, cited as the cause of most biomass superheater corrosion under chloride ash deposits, does not occur in the absence of these alkali salts when the chloride is present as HCl gas. Although a deposit is more corrosive at temperatures where it is molten than at temperatures where it is frozen, increasing superheater tube temperatures through

  17. Phase identification and internal stress analysis of steamside oxides on superheater tubes by means of X-ray diffraction

    DEFF Research Database (Denmark)

    Pantleon, Karen; Montgomery, Melanie

    Steamside oxides formed on plant exposed superheated tubes were investigated using X-ray diffraction. Phase identification and stress analysis revealed that on ferritic X20CrMoV12-1 pure Hematite and pure Magnetite formed and both phases are under tensile stress. IN contrast, on austenitic TP347H...

  18. Photo multiplier tubes candidates for the Cherenkov telescope array project

    International Nuclear Information System (INIS)

    Photo Multiplier Tubes (PMTs) are the most wide spread detectors for fast low-level light signals. They are commonly used as standard light sensors for camera systems in imaging atmospheric Cherenkov telescopes. Years ago, an improvement program for the PMT candidates for the Cherenkov Telescope Array (CTA) project was initialized with the companies Hamamatsu Photonics K.K. (Japan) and Electron Tubes Enterprises Ltd. (England). CTA is the next generation of imaging atmospheric Cherenkov telescopes for high energy gamma ray astrophysics. Therefore, we need PMTs with outstanding good parameters concerning quantum efficiency, pulse width, after-pulsing and transit time spread. The currently available ''super-bialkali'' PMTs show a peak Quantum Efficiency of 40% and have an enhanced collection efficiency of up to 95-98% for wavelengths≥400 nm. The pulse width averages around 3ns at a gain of 40000. Also, the after-pulsing for a set threshold level of ≥4 photo electrons is reduced down to 0,02%. We report on the measurement results of PMT R-12292-100 from Hamamatsu as the final version and the intermediate version PMT D569/3SA from Electron Tubes Enterprises as candidate PMTs for the CTA project.

  19. Hot Corrosion Behaviour of Type 316 Stainless Steel Tubes used in Reheaters and Superheaters of Oil-Fired Boilers

    International Nuclear Information System (INIS)

    High temperature corrosion behaviour of commercial type 316 stainless steel tubes has been studied in the presence of Na2 SO4 and NaCl at temperature ranged from 500 to 800 degree C. Tubes of different diameters ranging from 8 to 25 mm and thickness ranging from 1.9 to 4.3 mm were used in the study. The aggressive environment was 1 N Na2 SO4 + 1 N NaCl and vanadium compound was added as ammonium meta vanadate in some tests. corrosion kinetics based on weight change vs. Time measurements and microstructural analysis were used to determine the mode of corrosion attack and nature of the formed scales. As a result of the study it was found that the spilling increases as the temperature increases and led to weight loss, also the addition of vanadium to the solution caused a sharp increase in weight i.e. high corrosion rate, for all diameters. 11 Figs

  20. Thermal Analysis of Superheater Platen Tubesin Boilers

    Directory of Open Access Journals (Sweden)

    Shahram Falahatkar

    2014-01-01

    Full Text Available Superheaters are among the most important components of boilers and have major importance due to this operation in high temperatures and pressures. Turbines are sensitive to the fluctuation of superheaterstemperature;therefore even the slightest fluctuation in the outlet vapor temperature from the superheaters does damage the turbine axis and fins. Examining the potential damages of combustion in the boilers and components such as the superheaters can have a vital contribution to the progression of the productivity of boiler, turbine and the power plant altogether it solutions are to be fund to improve such systems. In this study, the focus is on the nearest tube set of superheaters to the combustion chamber.These types of tubes are exposed to a wide range ofcombustion flames such that the most heat transfer to them is radiation type.Here, the 320 MW boiler of Isfahan power plant (Iran, the combustion chamber, 16 burners and the platensuperheater tubes were remodeled by CFD technique. The fluid motion, the heat transfer and combustion processes are analyzed. The two-equation turbulence model of k-εis adopted to measure the eddy viscosity. The eddy dissipation model is used to calculate the combustion as well as the P-1 radiation model to quantify the radiation. The overheated zones of superheater tubes and the combustion chamber are identified in order toimprove this problem by applying the radiation thermal shields and knees with porous crust which are introduced as the new techniques.

  1. 超超临界机组锅炉末级过热器爆管原因分析%Cause Analysis on Bursting of Final Superheater Tubes of a Ultra Supercritical Boiler

    Institute of Scientific and Technical Information of China (English)

    肖国华; 李益民; 王理博

    2011-01-01

    The bursting and leakage reason of final superheater T91 steel tubes of a ultra super critical boiler was analyzed through chemical compositions analysis, microstructure analysis and mechanical properties test. The results show that the failure of the final superheater tubes was due to overheat which deteriorated the microstructure and mechanical properties of the tubes material. It was believable that the overheat of the bursting tubes was caused by blockage, according to the analysis results on the spot.%通过化学成分分析、金相检验、力学性能测试等手段对某电厂超超临界锅炉末级过热器T91钢管爆裂原因进行了分析.结果表明:爆管系超温运行所致,过热导致钢管材料显微组织老化、力学性能显著下降;并根据现场情况对爆裂管的超温原因进行了分析,认为异物堵塞造成超温的可能性较大.

  2. Microwave superheaters for fusion

    International Nuclear Information System (INIS)

    The microwave superheater uses the synchrotron radiation from a thermonuclear plasma to heat gas seeded with an alkali metal to temperatures far above the temperature of material walls. It can improve the efficiency of the Compact Fusion Advanced Rankine (CFAR) cycle described elsewhere in these proceedings. For a proof-of-principle experiment using helium, calculations show that a gas superheat ΔT of 20000K is possible when the wall temperature is maintained at 10000K. The concept can be scaled to reactor grade systems. Because of the need for synchrotron radiation, the microwave superheater is best suited for use with plasmas burning an advanced fuel such as D-3He. 5 refs

  3. Failure analysis on tube bursting of platen superheater of 600 MW ultra-supercritical power plant%600MW超临界机组屏式过热器爆管失效分析

    Institute of Scientific and Technical Information of China (English)

    阎光宗; 徐雪霞; 欧阳杰; 柯浩

    2011-01-01

    用断口宏观形貌、化学成分分析、常温力学性能检验、显微组织观察和扫描电镜断口分析法,对某电厂奥氏体不锈钢屏式过热器管爆管泄漏的原因进行分析.结果表明,爆管泄漏的屏式过热器管内壁存在原始缺陷,在机组运行中,该缺陷扩展最终导致爆管.%By use of the analysis of fracture appearance, chemical composition of the austenite stainless steel tube. microstructure metallography ohservation, mechanical properties examination and SEM fracture analysis, the reason of tube hursting of the platen superheater used in power plant was analyzed. The results show that the crack initiates from the original defect on the inner wall of the leaking tube , and during the generating set running the cracking propagates step by step, and leads to the tube bursting finally.

  4. 85 T/H 锅炉低温过热器爆管原因分析与总结%ANALYSIS AND SUMMARY ON TUBE RUPTURE IN THE LOW TEMPERATURE SUPERHEATER OF 85 T/H BOILER

    Institute of Scientific and Technical Information of China (English)

    任燕军

    2014-01-01

    This paper analyzes the cause of tube rupture in the low temperature superheater of 85t/h boiler in the company , tries to find out the reasons and point out the settlement method in order to provide reference for boiler maintenance work in the future .%文章对广州钢铁控股有限公司85t/h锅炉一级过热器管爆管的原因进行了分析,找出原因,并提出了相应的解决措施,以求对今后的锅炉检修维护工作有所借鉴。

  5. 超临界锅炉末级过热器爆管原因的分析%Burst Cause Analysis of Final-stage Superheater Tubes for a Supercritic al Boiler

    Institute of Scientific and Technical Information of China (English)

    赵慧传; 贾建民; 陈吉刚; 梁军; 杨红权; 尹成武

    2011-01-01

    为研究超临界锅炉末级过热器爆管的原因,对1台600MW超临界锅炉末级过热器爆管上游管和相关管样的内壁氧化物的宏观形态、微观结构,脱落氧化皮的微观结构、物相、各区域的微观形态和成分等进行了分析.结果表明:堵塞末级过热器下弯头造成过热器爆管的脱落氧化皮来自于T23/T91钢管的T23管段内壁,而非T91管段内壁;T23钢管内壁氧化皮为二层结构,外层为粗大柱状晶的纯磁铁矿(Fe3O4),内层为等轴细晶的含W和Cr的尖晶石;原生氧化皮内层存在一条或多条沿圆周方向排列的孔洞链,氧化皮容易沿孔洞链分离,从而造成氧化皮脱落.%In order to find the causes of tube burst failures encountered by the final-stage superheater of a 600 MW supercritical boiler, an analysis was carried out to both macrostructure and microstructure of the oxide scales taken from inner surface of relevant tube samples, and to the microstructure, phase, micromorphology and composition of fall-off scales. Results show that the failure has been caused by oxide scales split off from inner surface at T23 side of the T23/T91 joint, which blocked the lower elbow of the superheater and finally led to the tube burst. The scale on inner surface of T23 tube has a two-layer structure, of which the outer layer is the coarse columnar grain Fe3 O4 while the inner layer fine equiaxed spinel,containing W and Cr element. One or more hole-chains on inner surface of primitive oxide skin formed along the circumference direction are easy to break and cause the oxide skin to fall off.

  6. 生物质燃料锅炉20G钢低温过热器管爆裂失效分析%Burst failure analysis on 20G steel low temperature superheater tube of biomass-fired boiler

    Institute of Scientific and Technical Information of China (English)

    卿辉; 任耀剑; 孙智

    2014-01-01

    Reason for the failure of low temperature superheater tube of biomass-fired boiler during working was analyzed .The results show that the tube burst is related to the ash of biomass fuel and many short-terms over-high temperature .The alkali chloride and sulfide of the ash of biomass fuel accelerated corrosion and oxides generated , and the tube undergone short-term over-temperature repeatedly .Over-temperature caused pearlitic spheroidization and decreased strength of the material in the meantime .The tube cracking was due to the tube wall thinned by oxide abscission , and could not resist the boiler pressure .%某生物质燃料锅炉低温过热器管在运行中爆裂,对其失效原因进行了分析。结果表明,爆管的原因与生物质燃料灰分和多次短时超温有关。燃料灰分中的碱金属氯化物、硫化物使腐蚀加速,形成氧化物的速度加快,并使管道经历多次短时超温。超温造成组织中珠光体球化,使材料强度下降。氧化物脱落后,管壁的实际壁厚减薄,不足以承受管中的压力导致爆裂。

  7. Oxidation rate in ferritic superheater materials

    International Nuclear Information System (INIS)

    On the steam side of superheater tubes, compact oxide layers are formed which have a tendency to crack and flake off (exfoliate). Oxide particles then travel with the steam and can give rise to erosion damage in valves and on turbine blades. In an evaluation of conditions in superheater tubes from Swedish power boilers, it was found that the exfoliation frequency for one material quality (SS 2218) was greater than for other qualities. Against this background, a literature study has been carried out in order to determine which mechanisms govern the build-up of oxide and the exfoliation phenomenon. The study reveals that the oxide morphology is similar on all ferritic steels with Cr contents up to 5%. and that the oxide properties can therefore be expected to be similar. The reason why the exfoliation frequency is greater for tubes of SS 2218 is probably that the tubes have been exposed to higher temperatures. SS 2218 (2.25 Cr) is normally used in a higher temperature range which is accompanied by improved strength data as compared with SS 2216 (1 Cr). The principal cause of the exfoliation is said to be stresses which arise in the oxide during the cooling-down process associated with shutdowns. The stresses give rise to longitudinal cracks in the oxide, and are formed as a result of differences in thermal expansion between the oxide and the tube material. In addition, accounts are presented of oxidation constants and growth velocities, and thickness and running time. These data constitute a valuable basis for practical estimates of the operating temperature in routine checks and investigations into damage in superheater tubes. (au)

  8. Analysis on Bust Problem of 12Cr1MoV High Temperature Superheater Tubes of Boiler%锅炉用12Cr1MoV 高温段过热管爆裂分析

    Institute of Scientific and Technical Information of China (English)

    刘长春; 沈玉力

    2014-01-01

    The burst reason of 12Cr1MoV steel tube of high temperature superheater tubes of a power plant was analyzed through macroscopic and metallographic examination .The results showed that local corrosion in high temperature led to mul-tiple cross crack sources , and propagation of the cracks caused vertical cracks to the same radial direction in two places . Local corrosion in high temperature and fully nodular pearlite were the root cause of the failure .%某电厂的12Cr1MoV(φ42×5mm)高温段过热器管发生爆裂。采用宏观和微观分析方法,分析了爆裂原因。结果表明,该爆裂模式为局部高温腐蚀引发多处横裂源进一步导致2处同一径向的纵裂。局部高温腐蚀及珠光体完全球化是这起事故的根本原因。

  9. Rupture Causes Analysis and Countermeasures on Rear Platen Superheater Tube of 300 MW Power Station Boiler%300MW电站锅炉后屏过热器爆管原因分析和对策

    Institute of Scientific and Technical Information of China (English)

    黎小秋; 赵康文; 唐囡; 何可龙

    2012-01-01

    Based on the experimental data, an failure analysis about the causes of the dissimilar steel weld joints rupture in the rear platen superheater tube of a large power plant boiler has been done. The results demonstrated that the enriched carbon layers around the melting line, residual stress and stress concentration leads to a premature failure of the dissimilar steel weld joints, and the retrofitting measures are introduced to ensure the safe operation of the power station boiler. At the same time, it can also supply references to the failure analysis of the similar structure boiler heating tubes.%在试验的基础上,对某大型电站锅炉后屏过热器管异种钢焊缝破裂的原因进行了失效分析,结果表明熔合线增碳层,残余应力和应力集中导致了异种钢焊缝的早期失效,并提出了相应的改进措施以确保电站锅炉安全运行,同时,也可为同类型结构锅炉受热面管的失效分析提供参考.

  10. Study and design of platen superheater of 300 MW CFB boiler

    Energy Technology Data Exchange (ETDEWEB)

    Zhang, Man; Lv, Qinggang; Sun, Yunkai [Chinese Academy of Sciences, Beijing (China). Inst. of Engineering Thermophysics; Jiang, Xiaoguo [Harbin Boiler Company Limited, Harbin (China)

    2013-07-01

    In order to avoid overtemperature tube explosion of the platen superheater, the measurements of metal temperatures and the heat transfer coefficients of the platen superheater in a commercial 300 MW Circulating Fluidized Bed (CFB) boiler are conducted in this work. The measured data is analyzed and the theoretical calculation is made. On the basis, the reasonable steam flow path and the value range of heat transfer coefficient of the middle temperature platen superheater are applied for design. Furthermore, based on operation experience from several 300 MW CFB boilers, a design principle of the mass velocity and the arrangement of the platen superheater in the furnace is given.

  11. Analysis on Stress State of the Steam-side Oxide Scale in Superheater Tubes%锅炉过热器蒸汽侧氧化膜的应力状态分析

    Institute of Scientific and Technical Information of China (English)

    黄军林; 周克毅; 边彩霞; 胥建群

    2012-01-01

    火电机组锅炉过热器蒸汽侧氧化膜在机组变工况时可能发生开裂甚至脱落,对受热面安全性构成严重威胁。以超临界锅炉T91过热器管材为研究对象,在考虑温度对金属和氧化膜热膨胀系数影响的基础上,采用多层空心圆柱体模型,对3种不同工况下机组停炉过程中蒸汽侧氧化膜的稳态应力进行数值计算和分析。通过对各应力分量以及Mises等效应力进行分析,阐明了蒸汽侧氧化膜2种可能的开裂模式,同时得出了停炉过程中变工况后的负荷相同时蒸汽温度过低或者变工况后的蒸汽温度一定而负荷过低都可能导致氧化膜因等效应力过大而开裂甚至脱落的结论。%Exfoliation of an oxide scale from the steam side of superheater tubes has serious effects on the safety of thermal power plants.Considering the influence of temperature on coefficient of thermal expansion,a multi-layered hollow cylinder model was developed,and different stress components as well as von Mises equivalent stress in the steam-side oxide scale of T91 superheater tubes were then calculated under 3 different operating conditions.The calculation results show a potential for the occurrence of two distinct failure modes that may be activated by hoop stress or axial stress.It has been concluded that the failure of an oxide scale may occur due to the overlarge decrease of steam temperature or load with fixed other associated parameters.

  12. Integrated boiler, superheater, and decomposer for sulfuric acid decomposition

    Science.gov (United States)

    Moore, Robert; Pickard, Paul S.; Parma, Jr., Edward J.; Vernon, Milton E.; Gelbard, Fred; Lenard, Roger X.

    2010-01-12

    A method and apparatus, constructed of ceramics and other corrosion resistant materials, for decomposing sulfuric acid into sulfur dioxide, oxygen and water using an integrated boiler, superheater, and decomposer unit comprising a bayonet-type, dual-tube, counter-flow heat exchanger with a catalytic insert and a central baffle to increase recuperation efficiency.

  13. PFR superheater and reheater replacement and evaporator repair

    International Nuclear Information System (INIS)

    The paper gives details on the replacement superheaters and reheaters for the prototype Fast Reactor steam generator, including information on the choice of material and fabrication innovations. A repair technique for tube/tubeplate welds is described, and ultrasonic systems for examining these welds are outlined. (U.K.)

  14. Replacement superheaters and reheaters for the prototype fast reactor

    International Nuclear Information System (INIS)

    The Prototype Fast Reactor (PFR) at Dounreay first went into service in 1974. Heat from the reactor core is transferred to three identical liquid sodium circuits which in turn are coupled to three steam generator circuits. As designed, each of the three steam generator circuits comprises an evaporator designed to produce steam at a pressure of 17.85 MN/m2, a superheater and a reheater, each capable of raising the steam to a temperature of 5400C. The steam is used to drive a conventional turbo-alternator capable of generating 250 MW(e). During the early life of the plant, two leaks developed in tube-to-tubeplate welds in two of the superheaters and in one of the reheaters. The two superheaters were repaired and returned to service by explosive plugging of the leaking tubes, but in the case of the reheater, the tubeplate was so badly cracked by caustic products formed by the ingress of steam to the sodium that the reheater was unsuitable for further use. Because of this unexpected failure mechanism it was considered prudent to provide a set of spare units, so in 1979 six replacement tube bundles were ordered, three superheaters and three reheaters. The design, installation and testing of these are described. (author)

  15. Evaluation of Photo Multiplier Tube candidates for the Cherenkov Telescope Array

    Science.gov (United States)

    Mirzoyan, R.; Müller, D.; Hanabata, Y.; Hose, J.; Menzel, U.; Nakajima, D.; Takahashi, M.; Teshima, M.; Toyama, T.; Yamamoto, T.

    2016-07-01

    Photo Multiplier Tubes (PMTs) are the most wide spread detectors for fast, faint light signals. Six years ago, an improvement program for the PMT candidates for the Cherenkov Telescope Array (CTA) project was started with the companies Hamamatsu Photonics K.K. and Electron Tubes Enterprises Ltd. (ETE). For maximizing the performance of the CTA imaging cameras we need PMTs with outstanding good quantum efficiency, high photoelectron collection efficiency, short pulse width, very low afterpulse probability and transit time spread. We will report on the measurements of PMT R-12992-100 from Hamamatsu as their final product and the PMT D573KFLSA as one of the latest test versions from ETE as candidate PMTs for the CTA project.

  16. Corrosion of 2 1/4 Cr-1Mo steel under superheat transfer conditions

    International Nuclear Information System (INIS)

    Steam generators being developed for use with liquid metal fast breeder reactors (LMFBR's) will operate at substantially greater heat fluxes than conventional fossil-fired steam plants. To establish the corrosion allowance for the superheater tube walls, tests on 2 1/4Cr-1Mo steel with a heat flux of 126 kW/m2 across the specimen surface were conducted under steam conditions similar to those that will exist in LMFBR superheaters. (author)

  17. Effect of oxide films on hydrogen permeability of candidate Stirling heater head tube alloys

    Energy Technology Data Exchange (ETDEWEB)

    Schuon, S R; Misencik, J A

    1981-01-01

    High pressure hydrogen has been selected as the working fluid for the developmental automotive Stirling engine. Containment of the working fluid during operation of the engine at high temperatures and at high hydrogen gas pressures is essential for the acceptance of the Stirling engine as an alternative to the internal combustion engine. Most commercial alloys are extremely permeable to pure hydrogen at high temperatures. A program was undertaken at NASA Lewis Research Center (LeRC) to reduce hydrogen permeability in the Stirling engine heater head tubes by doping the hydrogen working fluid with CO or CO/sub 2/. Small additions of these gases were shown to form an oxide on the inside tube wall and thus reduce hydrogen permeability. A study of the effects of dopant concentration, alloy composition, and effects of surface oxides on hydrogen permeability in candidate heater head tube alloys is summarized. Results showed that hydrogen permeability was similar for iron-base alloys (N-155, A286, IN800, 19-9DL, and Nitronic 40), cobalt-base alloys (HS-188) and nickel-base alloys (IN718). In general, the permeability of the alloys decreased with increasing concentration of CO or CO/sub 2/ dopant, with increasing oxide thickness, and decreasing oxide porosity. At high levels of dopants, highly permeable liquid oxides formed on those alloys with greater than 50% Fe content. Furthermore, highly reactive minor alloying elements (Ti, Al, Nb, and La) had a strong influence on reducing hydrogen permeability.

  18. Cause Analysis and Preventive Measures on Bursting of High Temperature Superheater Tubes of 680 t/h Power Station Boiler%680t/h电站锅炉高温过热器爆管原因分析及预防措施

    Institute of Scientific and Technical Information of China (English)

    王小聪; 黎华; 马括; 卢忠铭

    2012-01-01

    Bursting of high temperature superheater tubes of 680 t/h power station boiler coccured twice reeently, and macroscopic examination, chemical compositions analysis and metallographic examination were investigated to find the casuse, the results showed that the failure was due to overheat which led to primary creep, then some effective prevention measures were taken.%某台680t/h电站锅炉高温过热器最近发生两起爆管事故,通过对爆管样管进行宏观检验、化学成分分析和金相检验判断爆管的根本原因。结果表明:由于长时间超温运行导致管子早期蠕变引起爆管,并采取了有效的预防措施。

  19. Evaluation of common genetic variants in 82 candidate genes as risk factors for neural tube defects

    Directory of Open Access Journals (Sweden)

    Pangilinan Faith

    2012-08-01

    Full Text Available Abstract Background Neural tube defects (NTDs are common birth defects (~1 in 1000 pregnancies in the US and Europe that have complex origins, including environmental and genetic factors. A low level of maternal folate is one well-established risk factor, with maternal periconceptional folic acid supplementation reducing the occurrence of NTD pregnancies by 50-70%. Gene variants in the folate metabolic pathway (e.g., MTHFR rs1801133 (677 C > T and MTHFD1 rs2236225 (R653Q have been found to increase NTD risk. We hypothesized that variants in additional folate/B12 pathway genes contribute to NTD risk. Methods A tagSNP approach was used to screen common variation in 82 candidate genes selected from the folate/B12 pathway and NTD mouse models. We initially genotyped polymorphisms in 320 Irish triads (NTD cases and their parents, including 301 cases and 341 Irish controls to perform case–control and family based association tests. Significantly associated polymorphisms were genotyped in a secondary set of 250 families that included 229 cases and 658 controls. The combined results for 1441 SNPs were used in a joint analysis to test for case and maternal effects. Results Nearly 70 SNPs in 30 genes were found to be associated with NTDs at the p MFTC, CDKN2A, ADA, PEMT, CUBN, GART, DNMT3A, MTHFD1 and T (Brachyury and included the known NTD risk factor MTHFD1 R653Q (rs2236225. The single strongest signal was observed in a new candidate, MFTC rs17803441 (OR = 1.61 [1.23-2.08], p = 0.0003 for the minor allele. Though nominally significant, these associations did not remain significant after correction for multiple hypothesis testing. Conclusions To our knowledge, with respect to sample size and scope of evaluation of candidate polymorphisms, this is the largest NTD genetic association study reported to date. The scale of the study and the stringency of correction are likely to have contributed to real associations failing to survive

  20. Evaluation of common genetic variants in 82 candidate genes as risk factors for neural tube defects

    LENUS (Irish Health Repository)

    Pangilinan, Faith

    2012-08-02

    AbstractBackgroundNeural tube defects (NTDs) are common birth defects (~1 in 1000 pregnancies in the US and Europe) that have complex origins, including environmental and genetic factors. A low level of maternal folate is one well-established risk factor, with maternal periconceptional folic acid supplementation reducing the occurrence of NTD pregnancies by 50-70%. Gene variants in the folate metabolic pathway (e.g., MTHFR rs1801133 (677 C > T) and MTHFD1 rs2236225 (R653Q)) have been found to increase NTD risk. We hypothesized that variants in additional folate\\/B12 pathway genes contribute to NTD risk.MethodsA tagSNP approach was used to screen common variation in 82 candidate genes selected from the folate\\/B12 pathway and NTD mouse models. We initially genotyped polymorphisms in 320 Irish triads (NTD cases and their parents), including 301 cases and 341 Irish controls to perform case–control and family based association tests. Significantly associated polymorphisms were genotyped in a secondary set of 250 families that included 229 cases and 658 controls. The combined results for 1441 SNPs were used in a joint analysis to test for case and maternal effects.ResultsNearly 70 SNPs in 30 genes were found to be associated with NTDs at the p < 0.01 level. The ten strongest association signals (p-value range: 0.0003–0.0023) were found in nine genes (MFTC, CDKN2A, ADA, PEMT, CUBN, GART, DNMT3A, MTHFD1 and T (Brachyury)) and included the known NTD risk factor MTHFD1 R653Q (rs2236225). The single strongest signal was observed in a new candidate, MFTC rs17803441 (OR = 1.61 [1.23-2.08], p = 0.0003 for the minor allele). Though nominally significant, these associations did not remain significant after correction for multiple hypothesis testing.ConclusionsTo our knowledge, with respect to sample size and scope of evaluation of candidate polymorphisms, this is the largest NTD genetic association study reported to date. The scale of the study and the

  1. Superheater corrosion in kraft recovery boilers; Korrosion hos oeverhettare i sodapannor. En oeversikt och diskussion

    Energy Technology Data Exchange (ETDEWEB)

    Bruno, F. [AaF-IPK, Stockholm (Sweden)

    1997-02-01

    Corrosion seems to be the most essential factor limiting the life and the availability of kraft recovery boilers. The steam temperature from the kraft recovery boiler has, seen from the view of electricity production and steam turbine operation, traditionally been kept moderate, especially in comparison with steam data from normal utility power plants. So the corrosion of the superheaters has been more a limitation for the temperature of the steam produced by the boiler than a life length limitation. Both the pressure and the temperature of the steam are limited by corrosion. The temperature of the boiling water, and hence the pressure, is limited by the corrosion in the lower furnace. The temperature of the steam is limited by the corrosion in the superheater. Kraft boiler superheater corrosion is here governed not only by the boiler design, but more by the mill chemistry and boiler operation practice. This report discusses the formation and the properties of the deposits and their relation to boiler operation and the corrosion of the superheater tube material. We have tried to understand the corrosion in the kraft boiler superheaters better by comparing with the experience from the utility boilers. 86 refs, 79 figs

  2. Geometrical Optimization for Outlet Tubes at Header of Top Roof Superheater in a Utility Boiler of a Power Plant%某电厂汽包锅炉过热器顶棚管联箱结构优化研究

    Institute of Scientific and Technical Information of China (English)

    吕玉贤; 庞力平; 李文学

    2014-01-01

    针对某电厂锅炉顶棚过热器频繁爆管现象,建立了与现场实际相同的几何模型,采用计算流体动力学方法对联箱内部流动情况进行数值研究。研究发现联箱三通附近由于静压分布异常,导致引入管周边的分支管静压较低,流量分配相对减少,发生传热恶化,进而发生爆管。该文提出优化的几何结构,通过对特定分支管引出方向进行调整,显著提升了并联分支管流量分配的均匀性,为电站锅炉分配联箱设计和结构优化提供一定的参考。%Numerical simulation was performed on the internal flow of header using the method of computational fluid dynamics with geometry model builded the same as practical field for the frequent rupture of roof superheater in a power station. The results indicate that due to the abnormal static pressure distribution in the area of Tee-junction of header, the static pressure of the branch pipes around inlet tube is so low, and the mass flow rate decreases relatively, then the heat transferation of tubes deteriorates,finally the tubes rupture. This paper proposes an improved geometric construction. By changing the leading direction of specific branch pipes, the uniformity of mass flow distribution in branch pipes promotes significient. It will offer a great reference for further design and optimization of distribution header in power station boilers.

  3. Design and fabrication of steam generators (superheaters) for the prototype fast breeder reactor 'MONJU'

    International Nuclear Information System (INIS)

    In liquid metal-cooled fast breeder reactors, steam generators are one of the important equipments, and emphasis has been placed on their development in various countries in the world. Also in Japan, centering around the Power Reactor and Nuclear Fuel Development Corp., the research and development in the wide range from the fundamentals on heat transfer and flow, materials and strength for steam generators to the manufacture, operation and various tests of large mock-ups including a 50 MW steam generator have been carried out. Further, as for the manufacture and inspection, the improvement of the method of welding tubes and tube plates, the adoption of a fine focus X-ray inspection apparatus and others were carried out. Moreover, as the maintenance technique, the ultrasonic flaw detection probes for the heating tubes were developed. The steam generators (superheaters) for the FBR 'Monju' power station are the heat exchangers of helical coil tube-shell type using SUS 321 steel as the heating tube material. Based on the results of these research and development, the design and manufacture of these superheaters and their installation in the reactor auxiliary building of the FBR 'Monju' power station were completed. The outline of the design, the research and development and the manufacture of the steam generators (superheaters) are reported. (K.I.)

  4. Superheater materials for waste incinerator boilers. Trials at the Hoegdalen plant

    International Nuclear Information System (INIS)

    In order to obtain an acceptable length of life for the superheaters in waste incinerated boilers a considerably lower steam temperature is used than when incinerating conventional fuel. In spite of this the life of the superheaters is unsatisfactory, with the occurrence of damage in some type of incinerator boilers after only a few years operation. The use of high alloyed material instead of conventional pressure vessel steels can increase the length of life and improve operational efficiency in existing incinerator boilers. Such tubes permit higher steam data for new plants. Cooled materials testing probes have been mounted in the flue gas duct close to the superheater in two boilers in the Hoegdalen plant, Stockholm. The materials temperatures have been maintained in the range 400-500 degrees C. Low metal losses have been obtained, in particular with Alloy 625, but also with Alloy 825 and Sandvik Sanicro 28. The attack on the tubes is corrosion, caused by the aggressive dust which is trapped in the superheaters. In these trials it has been shown that correct boiler design is very important, in conjunction with the choice of materials

  5. Superheater corrosion in biomass boiler - theories and tests in Vaestermalmsverket, Falun; Oeverhettarkorrosion i bioeldad panna - teorier och prov i Vaestermalmsverket, Falun

    Energy Technology Data Exchange (ETDEWEB)

    Roennquist, Eva-Marie

    2000-10-01

    It has lately been evident that a number of biomass-fired plants are experiencing major problems with corrosion of their superheaters. The major aim with this project is to contribute with increased knowledge in this area. The efforts to build up experience around different materials applicable for superheaters with high steam data is of great importance for future plants in Sweden. The main objective for 'Vaermeforsk' has been to transfer the experiences from this investigation to other boilers or plants with different types of fuel. This investigation has therefore been focused on the verification of SYCON's assumptions regarding the roles of chloride and alkali and the possibility of influencing/minimising superheater corrosion by optimisation of the fuel mix. Another important part was to verify that the boiler design, as such, does not create an unfavourable environment for the superheaters by producing reducing zones due to plume formation. Based on the above, the investigation has been divided into three loosely connected parts. (1) The role and reaction by chlorides in the deposits on a superheater, (2) Reducing environment - plume formation of non-combusted fuel, and (3) Choice of materials in the superheater. Serious corrosion has been detected in the superheater tubes of 'Vaestermalmsverket' in Falun. The material temperature was below 530 deg C. No serious inhomogeneous combustion problems or areas with reducing environments have been detected. The corrosion was therefore judged to be caused by alkali chlorides which condense on the superheater tubes. Tests with minor amounts of sulphur added to the biomass fuel have been shown to suppress the generation of alkali chlorides and their condensation on the superheater surfaces. A good correlation between calculated and measured values have been achieved. Very low corrosion rates have been measured on the test probes, constructed with different superheater material and placed in the

  6. Analysis of Superheater Work Under Creep Conditions

    Directory of Open Access Journals (Sweden)

    Piotr Duda

    2015-03-01

    Full Text Available The aim of this article is work modelling of superheater SH3. It is made of the austenitic stainless steel Super 304H. Its design temperature T is 604 C, and the design pressure P acting on the inner surface of the pipes is 284 bar. The high temperature is the reason of the superheater work under creep conditions. In this article calculations of the optimally mounted coil superheater SH3 are presented. The calculations are carried out first on the basis of the applicable European standards and with the help of the Auto Pipe program. Then, calculations are performed using the ANSYS program based on conducted creep tests and proposed creep equation. The coefficients in creep equation are determined based on the research conducted at the Instytut Metalurgii Żelaza in Gliwice. The model approximates the creep strain as the function of time and stress and this function is presented in the form of a three-dimensional surface . The results of calculations by both methods will be compared and conclusions will be presented. The performed analyzes can estimate the superheater coil remnant life and the usage after the selected time of its operation.

  7. Saint Laurent B1 nuclear power plant: Thermal and mechanical behavior of the 01 RES superheater condensates cooler

    Science.gov (United States)

    Mathiot, M.; Fromal, A.

    1982-04-01

    The thermal and mechanical performance of long thin tubes used to recover condensates from a PWR superheater and to raise the temperature of water fed into the steam generator was assessed, to see if temperature gradients liable to damage the tubes occur during load variations. Results show that maximum stress occurs during stable operation at nominal load. Stress decreases in transient regimes. Stress is decreased by modifying the procedure for opening the steam inlet valve.

  8. Results of examination of the TGMP-314 boiler superheaters of the power-generating units at Kashira state district power plant using a magnetic ferrite meter

    Science.gov (United States)

    Bogachev, V. A.; Pshechenkova, T. P.; Shumovskaya, M. A.

    2016-07-01

    The results of investigating the elemental composition of the scale and the metal of a tube circuit from the austenitic steel grade 12Cr18Ni12Ti are presented. The superheater is part of the high-pressure convection steam superheater of a TGMP-314 supercritical-pressure gas-and-oil-fired once-through boiler that had been operated for a long period of time. A structurally transformed layer, poor in iron, manganese, and chromium and rich in nickel was detected on the outer surface. The layer consisted predominantly of the FeNi3 phase with ferromagnetic properties. The heat-resistance test of the steel in contact with ash that simulated the combustion products of fuel oil showed that the higher the temperature and the longer the test time, the higher the content of the ferritic phase in the layer was. The established pattern of the structural transformations underlies a method for nondestructive control of the thermal nonuniformity and detection of "worst" tube circuits of superheaters from austenitic steel. The magnetic ferritometry complements the conventional selective thickness gauging that does not characterize the condition of the heating surfaces of hightemperature steel grades to the full extend. Data on damageability of high-pressure convection superheaters and low-pressure second-stage convection superheaters with rarefied tube banks of TGMP-314 boilers are presented. The damage is caused by overheating resulting from the nonuniform temperature field at the inlet and by the nonuniform flue gas velocity field in rarefied superheater banks. Sections of the tube circuits from the steel grade 12Cr18Ni12Ti, outlet superheater stages of the TGMP-314 boiler of the power-generating units at Kashira SDPP were examined using an MF-51NTs AKASKAN magnetic ferrite meter. Thermal nonuniformity was established and the "worst" superheater tube circuits were detected. It was shown that the zones with the "worst" and damaged tube circuits coincide. The results of examining

  9. A steam separator-superheater apparatus

    International Nuclear Information System (INIS)

    Description is given of a separator-superheater apparatus comprising an outer enclosure containing a separating-unit and a steam superheating unit according to the main patent. The present addition relates to an improvement in that apparatus, characterized in that the separating unit and the superheating unit, mounted in two distinct portions of the outer enclosure, are divided into the same number of sub-units of each unit being identical and operating in parallel, and in that to each separator sub-unit is associated a superheater sub-unit, said sub-units being mounted in series and located in one in the other of the enclosure two portions, respectively. This can be applied to the treatment of the exhaust steam of a turbine high pressure body, prior to re-injecting said steam into the low pressure body

  10. A steam superheater exchanger provided with two coaxial casings and an horizontal axis

    International Nuclear Information System (INIS)

    This invention concerns the general lay-out of an horizontal axis separator-superheater for supplying steam to a high power turbine, particularly for a nuclear power station. The invention significantly reduces the length of the pipework connecting the superheated steam outlet and its inlet to the turbine. For this, the outer casing is provided with a coaxial internal annular sleeve in which are housed, one above the other, the separator and the bundle of superheater tubes through which circulates the water emulsion to be separated and steam to be superheated. At the end of its treatment, the superheated steam spreads out in the space between the sleeve and the outer casing from whence it can be drawn off at any point of its periphery, thus making it possible to choose an extraction point as near as possible to the inlet of the turbine to be fed

  11. SEM Investigation of Superheater Deposits from Biomass-Fired Boilers

    DEFF Research Database (Denmark)

    Jensen, Peter Arendt; Frandsen, Flemming; Hansen, Jørn;

    2004-01-01

    adopted to minimize deposit problems at the two boilers. At Masnedø the final superheater steam temperature is 520 °C, no soot blowing of the superheaters is applied and a relatively large superheater area is used. At Ensted, an external wood-fired superheater is used in order to obtain a final steam...... layer was probably generated by in-situ reaction between KCl and Si-rich ash particles, which leads to release of chlorine-containing gases. The innermost layer contained many sublayers of mainly iron oxide, KCl, and K2SO4. The Ensted deposit had a maximum thickness of a few centimeters. The...

  12. Long-term creep rupture strength of weldment of Fe-Ni based alloy as candidate tube and pipe for advanced USC boilers

    Energy Technology Data Exchange (ETDEWEB)

    Bao, Gang; Sato, Takashi [Babcok-Hitachi K.K., Hiroshima (Japan). Kure Research Laboratory; Marumoto, Yoshihide [Babcok-Hitachi K.K., Hiroshima (Japan). Kure Div.

    2010-07-01

    A lot of works have been going to develop 700C USC power plant in Europe and Japan. High strength Ni based alloys such as Alloy 617, Alloy 740 and Alloy 263 were the candidates for boiler tube and pipe in Europe, and Fe-Ni based alloy HR6W (45Ni-24Fe-23Cr-7W-Ti) is also a candidate for tube and pipe in Japan. One of the Key issues to achieve 700 C boilers is the welding process of these alloys. Authors investigated the weldability and the long-term creep rupture strength of HR6W tube. The weldments were investigated metallurgically to find proper welding procedure and creep rupture tests are ongoing exceed 38,000 hours. The long-term creep rupture strengths of the HST weld joints are similar to those of parent metals and integrity of the weldments was confirmed based on with other mechanical testing results. (orig.)

  13. Long term testing of materials for tube shielding, stage 2; Laangtidsprovning av tubskyddsmaterial, etapp 2

    Energy Technology Data Exchange (ETDEWEB)

    Norling, Rikard; Hjoernhede, Anders; Mattsson, Mattias

    2012-02-15

    Circulating Fluidized Bed (CFB) boilers are commonly used for combustion of biomass and are used to some extent for Waste-to-Energy (WtE) plants as well. The superheaters of the latter are for obvious reasons more prone to suffer from high temperature corrosion caused by the corrosive species in the fuel, mainly chlorides. Frequently the final (hottest) superheater is positioned in the loop seal, where the circulating bed material is returned to the furnace after being separated from the flue gas by a cyclone. The environment in the loop seal is relatively free of chlorides, since these primarily follow the flue gas into the convection pass. Hence, higher steam temperature can be allowed without excessive damage to the final superheater. On the other hand the superheaters, which are located in the convection pass, are more exposed to the corrosive species of the flue gas. Further, they are eroded by particles entrained in the gas flow. Particles and condensing gaseous species are to a large extent deposited on the superheaters, which limits the heat transfer and promotes corrosion. The deposits are regularly removed e.g. by soot blowers. The pressurized steam from soot blowers causes additional erosion damage to that caused by entrained particles. It shall be noted that the actual damage is caused by a combined mechanism of erosion and corrosion denoted erosion-corrosion, which usually results in dramatically accelerated wear. To avoid excessive erosion damage on the superheater tubes the first tube row of each bundle is protected by tube shielding. In its simplest form the shields are made from a steel sheet that has been bent into a semi-circular half-cylinder shell. These shields are attached onto the wind-side of the tubes by hangers. A typical material for tube shielding is the austenitic high temperature resistant stainless steel 253MA. Life of tube shielding depends on numerous factors such as boiler design, superheater location, fuel and operating

  14. Nonlinear Superheat Control of a Refrigeration Plant using Backstepping

    DEFF Research Database (Denmark)

    Rasmussen, Henrik

    2008-01-01

    This paper proposes a novel method for superheat and capacity control of refrigeration systems. The main idea is to control the superheat by the compressor speed and capacity by the refrigerant flow. A new low order nonlinear model of the evaporator is developed and used in a backstepping design of...

  15. The under sodium leak in the PFR Superheater 2 in February 1987

    International Nuclear Information System (INIS)

    An under sodium leak occurred in the Prototype Fast Reactor (PFR) Superheater 2, at Dounreay, UK, in February 1987. During this leak event a total of 40 tubes failed, each one equivalent to a Double-ended-guillotine failure (DEGF). The 39 secondary failures occurred in a time of about 10s. In this paper the plant measurements and automatic protection system/shutdown system responses during the leak event are described. The damage observed to the tube bundle will also be detailed. Possible leak evolution histories are postulated and the pressure loadings predicted for the Intermediate Heat Exchangers (IHXs) from upper bound scenarios are presented. These pressure loadings are compared to those predicted for the Design Basis Accident (DBA) which was used in the Safety Case for the plant at the time of this event. It is shown that the pressure in the IHX during this multiple tube failure event in the Superheater did not exceed the predicted values for the DBA, which was based on the failure of a single tube in the Evaporator. A leak evolution mechanism will be described along with the supporting experimental data which justifies the interpretation that, in this event, with the exception of the initial leak, tube failures were due to overheating and that corrosion and wastage were not of importance. The metallurgical structure of the tubes in the bundle indicate that, with the exception of the primary and possibly one or two of the fretted tubes, the tubes failed after the trip which removed the internal cooling of the tubes. This data also shows that the tubes which failed early in the trip, when internal tube pressure was high, failed at lower temperatures, than those which failed later in the trip, when the internal pressure had reduced significantly. Over and above the tubes which failed, many other tubes experienced high temperatures, > 800 deg. C, but did not fail because they only experienced elevated temperatures late on in the incident, after the internal tube

  16. Effect of superheat and electric field on saturated film boiling

    Science.gov (United States)

    Pandey, Vinod; Biswas, Gautam; Dalal, Amaresh

    2016-05-01

    The objective of this investigation is to study the influence of superheat temperature and applied uniform electric field across the liquid-vapor interface during film boiling using a coupled level set and volume of fluid algorithm. The hydrodynamics of bubble growth, detachment, and its morphological variation with electrohydrodynamic forces are studied considering the medium to be incompressible, viscous, and perfectly dielectric at near critical pressure. The transition in interfacial instability behavior occurs with increase in superheat, the bubble release being periodic both in space and time. Discrete bubble growth occurs at a smaller superheat whereas vapor columns form at the higher superheat values. Destabilization of interfacial motion due to applied electric field results in decrease in bubble separation distance and increase in bubble release rate culminating in enhanced heat transfer rate. A comparison of maximum bubble height owing to application of different intensities of electric field is performed at a smaller superheat. The change in dynamics of bubble growth due to increasing superheat at a high intensity of electric field is studied. The effect of increasing intensity of electric field on the heat transfer rate at different superheats is determined. The boiling characteristic is found to be influenced significantly only above a minimum critical intensity of the electric field.

  17. Degradation of superheater headers during long-term service

    International Nuclear Information System (INIS)

    Majority of superheater headers used in polish power plants as well as heat and power-generating plants have already worked for over 100 thousand hours. A superheater is on of the most important elements of a boiler. They have operated at a temperature about 500-550 oC and pressure of 10-18 MPa. The paper presents some results of the X20CrMoV121 steels microstructure and properties investigations after long-term service superheater headers of 360 and 500 MW blocks. (author)

  18. Neural network for prediction of superheater fireside corrosion

    Energy Technology Data Exchange (ETDEWEB)

    Makkonen, P. [Foster Wheeler Energia Oy, Karhula R and D Center, Karhula (Finland)

    1998-12-31

    Superheater corrosion causes vast annual losses to the power companies. If the corrosion could be reliably predicted, new power plants could be designed accordingly, and knowledge of fuel selection and determination of process conditions could be utilized to minimize superheater corrosion. If relations between inputs and the output are poorly known, conventional models depending on corrosion theories will fail. A prediction model based on a neural network is capable of learning from errors and improving its performance as the amount of data increases. The neural network developed during this study predicts superheater corrosion with 80 % accuracy at early stage of the project. (orig.) 10 refs.

  19. Fireside corrosion of superheaters/reheaters in advanced power plants

    Energy Technology Data Exchange (ETDEWEB)

    Syed, A.U.; Simms, N.J.; Oakey, J.E. [Cranfield Univ. (United Kingdom). Energy Technology Centre

    2010-07-01

    being used for the development of statistical models to predict the lifetimes of candidate materials for use in superheaters/reheaters in the advanced power plants. (orig.)

  20. Automatic Tuning of the Superheat Controller in a Refrigeration Plant

    DEFF Research Database (Denmark)

    Rasmussen, Henrik; Thybo, Claus; Larsen, Lars F. S.

    2006-01-01

    This paper proposes an automatic tuning of the superheat control in a refrigeration system using a relay method. By means of a simple evaporator model that captures the important dynamics and non-linearities of the superheat a gain-scheduling that compensates for the variation of the process gain...... can be obtained from tuning in only one operation point. The proposed method is validated by experimental results....

  1. Nonlinear Superheat and Evaporation Temperature Control of a Refrigeration Plant

    DEFF Research Database (Denmark)

    Rasmussen, Henrik; Thybo, Claus; Larsen, Lars F. S.

    2006-01-01

    This paper proposes novel control of the superheat of the evaporator in a refrigeration system. A new model of the evaporator is developed and based on this model the superheat is transferred to a referred variable. It is shown that control of this variable leads to a linear system independent of...... the working point. The model also gives a method for control of the evaporation temperature. The proposed method is validated by experimental results....

  2. Evaluation of candidate Stirling engine heater tube alloys after 3500 hours exposure to high pressure doped hydrogen or helium

    Science.gov (United States)

    Misencik, J. A.; Titran, R. H.

    1984-01-01

    The heater head tubes of current prototype automotive Stirling engines are fabricated from alloy N-155, an alloy which contains 20 percent cobalt. Because the United States imports over 90 percent of the cobalt used in this country and resource supplies could not meet the demand imposed by automotive applications of cobalt in the heater head (tubes plus cylinders and regenerator housings), it is imperative that substitute alloys free of cobalt be identified. The research described herein focused on the heater head tubes. Sixteen alloys (15 potential substitutes plus the 20 percent Co N-155 alloy) were evaluated in the form of thin wall tubing in the NASA Lewis Research Center Stirling simulator materials diesel fuel fired test rigs. Tubes filled with either hydrogen doped with 1 percent CO2 or with helium at a gas pressure of 15 MPa and a temperature of 820 C were cyclic endurance tested for times up to 3500 hr. Results showed that two iron-nickel base superalloys, CG-27 and Pyromet 901 survived the 3500 hr endurance test. The remaining alloys failed by creep-rupture at times less than 3000 hr, however, several other alloys had superior lives to N-155. Results further showed that doping the hydrogen working fluid with 1 vol % CO2 is an effective means of reducing hydrogen permeability through all the alloy tubes investigated.

  3. Limit of Superheat of Polystyrene-Cyclohexane Solutions: Theory

    Directory of Open Access Journals (Sweden)

    John Howland Jennings

    2012-06-01

    Full Text Available A theory for the surface tension of polymer solutions is used along with classical nucleation theory to predict the temperature rise above the solvent limit of superheat due to addition of polymer.  Polystyrene, of 2000 and 4000 molecular weight, was added to cyclohexane and it produced a linear rise in the superheat to an extent that depends upon both molecular weight and concentration.  The theory is used in the athermal case (dT = 0 to give the additional temperature rise with respect to weight fraction.

  4. Nonlinear superheat and capacity control of a refrigeration plant

    DEFF Research Database (Denmark)

    Rasmussen, Henrik; Larsen, Lars F. S.

    This paper proposes a novel method for superheat and capacity control of refrigeration systems. A new low order nonlinear model of the evaporator is developed and used in a backstepping design of a nonlinear controller. The stability of the proposed method is validated theoretically by Lyapunov...

  5. In-situ tube burst testing and high-temperature deformation behavior of candidate materials for accident tolerant fuel cladding

    Energy Technology Data Exchange (ETDEWEB)

    Gussev, Maxim N.; Byun, Thak Sang; Yamamoto, Yukinori; Maloy, Stuart A.; Terrani, Kurt A.

    2015-11-01

    The high resistance of cladding to plastic deformation and burst failure is one of the most essential properties of accident tolerant fuel (ATF) for maintaining structural integrity during a loss-of-coolant accident (LOCA) since the deformation and burst behavior governs the cooling efficiency of flow channels and process of fission product release. To simulate and evaluate such deformation and burst process of thin-walled cladding, an in-situ testing and evaluation method has been developed on the basis of visual imaging and image analysis techniques. The method uses a specialized optics system consisted of a high-resolution video camera, light filtering unit, and monochromatic light sources, and the in-situ testing is performed using a 50 mm long pressurized thin-walled tubular specimen set in a programmable furnace. In this study eleven (11) candidate cladding materials for ATF, i.e., 6 FeCrAl alloys and 5 nanostructured steels, were tested using the newly developed method, and the time-dependent images were analyzed to produce detailed deformation and burst data such as true hoop stress, strain (creep) rate, and failure stress. Relatively soft FeCrAl alloys deformed and burst below 800°C while negligible strain rates were measured for higher strength alloys and/or for relatively thick wall specimens.

  6. Examining the anti-candidal activity of 10 selected Indian herbs and investigating the effect of Lawsonia inermis extract on germ tube formation, protease, phospholipase, and aspartate dehydrogenase enzyme activity in Candida albicans

    Science.gov (United States)

    Ravichandran, Sripathy; Muthuraman, Sundararaman

    2016-01-01

    Objective: The objective of the study is to identify potential anti-candidal agents from natural resources and elucidate the effect of Lawsonia inermis extract on major virulent factors of Candida albicans. Materials and Methods: Plants, the most abundant and readily available resource of diverse bioactives, were chosen for the anti-candidal screening study. Ten different plants that were proven to have antimicrobial activity but not explored much for anti-candidal activity were chosen for this study. Ethyl acetate extract of these plant leaves were tested for the anti-candidal activity. Extracts with good anti-candidal activity were further screened for its effect in C. albicans germ tube formation and enzyme (protease, phospholipase, and aspartate dehydrogenase) activity. Results: Among 10 plants screened, L. inermis extract showed complete inhibition of C. albicans. On further evaluation, this extract completely inhibited C. albicans germ tube formation in serum until the end of incubation period (3 h). This extract also exhibited dose-dependent inhibitory activity against two major virulent enzymes of C. albicans, proteases (27–33%) and phospholipases (44.5%). In addition to it, this extract completely inhibited both the isoforms of constitutive candidal enzyme aspartate dehydrogenase, thereby affecting amino acid biosynthesis. Conclusion: Thus, this study confirms the anti-candidal potential of L. inermis and hence can be considered further for development of anti-candidal drug. PMID:26997722

  7. Some aspects of metallurgical assessment of boiler tubes-Basic principles and case studies

    International Nuclear Information System (INIS)

    Microstructural changes in boiler tubes during prolong operation at high temperature and pressure decrease load bearing capacity limiting their useful lives. When the load bearing capacity falls below a critical level depending on operating parameters and tube geometry, failure occurs. In order to avoid such failures mainly from the view point of economy and safety, this paper describes some basic principles behind remaining life assessment of service exposed components and also a few case studies related to failure of a reheater tube of 1.25Cr-0.5Mo steel, a carbon steel tube and final superheater tubes of 2.25Cr-1Mo steel and remaining creep life assessment of service exposed but unfailed platen superheater and reheater tubes of 2.25Cr-1Mo steel. Sticking of fly ash particles causing reduction in effective tube wall thickness is responsible for failure of reheater tubes. Decarburised metal containing intergranular cracks at the inner surface of the carbon steel tube exhibiting a brittle window fracture is an indicative of hydrogen embrittlement responsible for this failure. In contrast, final superheater tube showed that the failure took place due to short-term overheating. The influence of prolong service revealed that unfailed reheater tubes exhibit higher tensile properties than that of platen superheater tubes. In contrast both the tubes at 50 MPa meet the minimum creep rupture properties when compared with NRIM data. The remaining creep life of platen superheater tube as estimated at 50 MPa and 570 deg. C (1058 oF) is more than 10 years and that of reheater tube at 50 MPa and 580 deg. C (1076 oF) is 9 years

  8. Further development of the water separator - intermediate superheater for nuclear power stations with LWR's

    International Nuclear Information System (INIS)

    A superheater with two heating steam stages which is optimised and favourable as regards heat consumption, and which has increased heat transmission surfaces is introduced. These large surfaces can be accommodated without problems with the described, horizontal separator - superheater design. (RW)

  9. Removal of External Deposits on Boiler Tubes

    Directory of Open Access Journals (Sweden)

    C. P. De

    1970-07-01

    Full Text Available The superheater tubes in Port and Starboard boilers were found to have completely clogged by heavy deposits, which on analysis mainly vanadium pentoxide and sodium sulphmatter. The cleaning of the deposits was accomplished by alternate spraying with 15-20 per cent hydrogen peroxide and washing with hot water jets. Over the past two years, since the date of cleaning, the IN ship is operating without any trouble in the boilers.

  10. Development of Computational Capabilities to Predict the Corrosion Wastage of Boiler Tubes in Advanced Combustion Systems

    Energy Technology Data Exchange (ETDEWEB)

    Kung, Steven; Rapp, Robert

    2014-08-31

    A comprehensive corrosion research project consisting of pilot-scale combustion testing and long-term laboratory corrosion study has been successfully performed. A pilot-scale combustion facility available at Brigham Young University was selected and modified to enable burning of pulverized coals under the operating conditions typical for advanced coal-fired utility boilers. Eight United States (U.S.) coals were selected for this investigation, with the test conditions for all coals set to have the same heat input to the combustor. In addition, the air/fuel stoichiometric ratio was controlled so that staged combustion was established, with the stoichiometric ratio maintained at 0.85 in the burner zone and 1.15 in the burnout zone. The burner zone represented the lower furnace of utility boilers, while the burnout zone mimicked the upper furnace areas adjacent to the superheaters and reheaters. From this staged combustion, approximately 3% excess oxygen was attained in the combustion gas at the furnace outlet. During each of the pilot-scale combustion tests, extensive online measurements of the flue gas compositions were performed. In addition, deposit samples were collected at the same location for chemical analyses. Such extensive gas and deposit analyses enabled detailed characterization of the actual combustion environments existing at the lower furnace walls under reducing conditions and those adjacent to the superheaters and reheaters under oxidizing conditions in advanced U.S. coal-fired utility boilers. The gas and deposit compositions were then carefully simulated in a series of 1000-hour laboratory corrosion tests, in which the corrosion performances of different commercial candidate alloys and weld overlays were evaluated at various temperatures for advanced boiler systems. Results of this laboratory study led to significant improvement in understanding of the corrosion mechanisms operating on the furnace walls as well as superheaters and reheaters in

  11. CFD modeling of a boiler's tubes rupture

    International Nuclear Information System (INIS)

    This paper reports the results of a study on the reason for tubes damage in the superheater Platen section of the 320 MW Bisotoun power plant, Iran. The boiler has three types of superheater tubes and the damage occurs in a series of elbows belongs to the long tubes. A three-dimensional modeling was performed using an in-house computational fluid dynamics (CFD) code in order to explore the reason. The code has ability of simultaneous solving of the continuity, the Reynolds-Averaged Navier-Stokes (RANS) equations and employing the turbulence, combustion and radiation models. The whole boiler including; walls, burners, air channels, three types of tubes, etc., was modeled in the real scale. The boiler was meshed into almost 2,000,000 tetrahedral control volumes and the standard k-ε turbulence model and the Rosseland radiation model were used in the model. The theoretical results showed that the inlet 18.9 MPa saturated steam becomes superheated inside the tubes and exit at a pressure of 17.8 MPa. The predicted results showed that the temperature of the steam and tube's wall in the long tubes is higher than the short and medium size tubes. In addition, the predicted steam mass flow rate in the long tube was lower than other ones. Therefore, it was concluded that the main reason for the rupture in the long tubes elbow is changing of the tube's metal microstructure due to working in a temperature higher than the design temperature. In addition, the structural fatigue tension makes the last elbow of the long tube more ready for rupture in comparison with the other places. The concluded result was validated by observations from the photomicrograph of the tube's metal samples taken from the damaged and undamaged sections

  12. Structural Integrity Analysis On Superheater Material Of Plt Surabaya

    International Nuclear Information System (INIS)

    Structural integrity analysis on superheater material of PLTU Suralaya has been carried out. Tested material was carbon steel SA 209 T1A and ferritic steel SA 213 T2 based on data specification from PLTU Suralaya. All stages in analysis include collection of operation history background and material specification, visual examination, radiography testing, chemical composition testing, hardness testing and metallography testing. From analysis and testing results, it is shown that material suffered from decarburization on outside surface (00), hardness decrease and pitting corrosion on 00 surface. Primary cause of pipe failure is decarburization due to carbon element inside material that diffuses from inside to OD surface so that microstructure is only pure ferrite

  13. Factors determining the durability of steam superheater chambers

    Directory of Open Access Journals (Sweden)

    J. Lisok

    2008-11-01

    Full Text Available Purpose: The paper presents the results of calculations of effort for the material of selected superheater chambers’constructional systems in unsteady operation conditions.Design/methodology/approach: In model tests, the influence was analysed of internal pressure andtemperature gradient in the chamber wall on the distribution and value of stress . In the calculations, the processof hot start-up of a boiler was simulated, which was accompanied by short thermal shock induced by rapid coolingof the chamber inner wall.Findings: The random nature of thermal shock, which in the industrial practice may occur in any row and to anynumber of coil pipes, determines the value of maximal stress and the area of its occurrence. It has a significantinfluence on the possibility of forecasting the durability of chambers in working conditions.Research limitations/implications: The research has evidenced a link between the method of forcingthermal shock and the value of maximal stress in the area of bridges.Practical implications: The research has demonstrated the existence of connection between the way of forcingthermal shock and the stress value which, depending on the variant of cooling the chamber, ranges between150-370 MPa. These results are very important to the industry connected with the structure of pipelines.Originality/value: It was found that the primary reason for the superheater chamber damage, leading to crackformation, are thermal shocks. A link has been shown between the method of forcing the thermal shock and thevalue of maximal stress in the zone of bridges.

  14. Modeling of fire-tube boilers

    OpenAIRE

    Ortiz, F.J. Gutiérrez

    2011-01-01

    Abstract In fire-tube boilers, the flue gas passes inside boiler tubes, and heat is transferred to water on the shell side. A dynamic model has been developed for the analysis of boiler performance, and Matlab has been applied for integrating it. The mathematical model developed is based on the first principles of mass, energy and momentum conservations. In the model, the two parts of the boiler (fire/gas and water/steam sides), the economizer, the superheater and the heat recovery...

  15. Investigation and analysis of short overheat in boiler tube failure in power plant units

    International Nuclear Information System (INIS)

    Boiler tube failure are the main cause of forced outages of power generating units and due to cost, Penalty is very high. Sources and reasons of tube failures are various, but it can be generally categorized by mechanical and corrosion factors with 81% and 19% contributions, respectively. Among the mechanical factors short overheat has the major contribution in water wall and superheater tube, failure. In this paper short overheat mechanism (with appearance and metallurgical features) and its prevention method is over viewed

  16. Evaluation of tube shielding; Utvaerdering av tubskyddsmaterial

    Energy Technology Data Exchange (ETDEWEB)

    Hjoernhede, Anders; Westberg, Stig-Bjoern; Henderson, Pamela; Wetterstroem, Jonas; Jonasson, Anna

    2007-12-15

    Problems with soot-blowing have increased recently because of the poor fuel quality. Studies show that removing all the deposit by soot-blowing increases the metal loss of the superheaters, which drastically shortens component lifetimes. A simple, effective and common way of increasing the lifetime is to use tube shielding. Austenitic stainless steels seem to be the type of material most commonly used for tube shielding. It is thought that they give better protection against material removal than ferritic steels, but the cost of austenitics is several times greater than ferritic steels. It is clear that there is a significant economic advantage in choosing the right material for tube shielding, even though it might be expected that the cheaper materials do not perform as well as the more expensive ones. The reason for the study reported here is that very little material data exists in the literature. Few, if any tests have been performed to study the choice of material for tube shielding. The goal was to compare and evaluate a number of materials in a boiler to see if it is possible to replace the shielding material presently used with cheaper alternatives. About a dozen different shielding materials were installed and exposed for 4000 hours on primary- and secondary superheaters in a waste-fired boiler in Norrkoeping (Haendeloe Boiler 14.75MW). In total, 130 m of test material were installed and measured in several positions: a least 150 thickness measurements, before and after, were made on every tube shield. The results showed that the greatest attack was found on the secondary superheater shielding, where both the gas- and steam temperatures were higher. When considering cost and lifetime Sicromal 10 and 12 (however not Sicromal 8) and 15Mo3 are recommended as being better than 253 MA. The results should be of interest to most plants firing biomass or waste

  17. The experimental and engineering programmes to support the PFR Safety Case following the Superheater 2 under sodium leak: In particular, large scale experiments in the Super Noah Rig at Dounreay

    International Nuclear Information System (INIS)

    The original safety Case for the Prototype Fast Reactor (PFR) at Dounreay was based on the Double-ended-guillotine failure (DEGF) of one tube followed by six more DEGFs spread out at 3s intervals. Because the DEGF flowrate in the Evaporator units was considerably greater than those for the Superheater and Reheater units, pressure loading predictions were based on a leak incident in the Evaporator. As data became available from sodium-water reaction experiments, this Design Basis Accident (DBA) was revised to be the failure of a single tube (1DEGF). Pressure loadings for the plant were still based on the Evaporator. The plant was, however, designed against the original DBA of 1+6 DEGFs. The under sodium leak in Superheater 2, in which a total of 40 DEGFs occurred in a short period of time, cast doubt on the choice of DBA for PFR and it was obvious that multiple tube failure incidents had to be considered. A revised Safety Case for PFR was constructed based on an event tree and is presented in this paper. Also, in this paper the engineering work carried out on the plant in order to reduce the frequency of occurrence of multiple tube failures and the R and D programme initiated to remove unnecessary pessimism from the postulated multiple tube failure incidents are described. (author). 2 refs, 16 figs, 1 tab

  18. Preliminary thermal/hydraulic sizing calculations for duplex tube evaporator/superheater (interchangeable units). Revision 1

    Energy Technology Data Exchange (ETDEWEB)

    Waszink, R.P.; Hwang, J.Y.; Efferding, L.E.

    1974-06-01

    This is a preliminry thermal/hydraulic report reflecting work under Subtask 6.2 of Ref. 1.1. This report is an extension of the previous thermal/hydraulic design report. Parts of this report have been transmitted to GE. The detailed design basis, listed by source, is given. Additional details are discussed.

  19. Evaluation of candidate Stirling engine heater tube alloys after 3500 hours exposure to high pressure doped hydrogen or helium. Final report

    Energy Technology Data Exchange (ETDEWEB)

    Misencik, J.A.; Titran, R.H.

    1984-10-01

    Sixteen commercial tubing alloys were endurance tested at 820/sup 0/ C, 15 MPa in a diesel-fuel fired Stirling engine simulator materials test rig: iron-base N-155, A-286, Incoloy 800, 19-9DL, CG-27, W-545, 12RN72, 253MA, Sanicro 31H and Sanicro 32; nickel-base Inconel 601, Inconel 625, Inconel 718, Inconel 750 and Pyromet 901; and cobalt-base HS-188. The iron-nickel alloys CG-27 and Pyromet 901 exhibited superior oxidation/corrosion resistance to the diesel-fuel combustion products and surpassed the design criterias' 3500 h creep-rupture endurance life. Three other alloys, Inconel 625, W-545, and 12RN72, had creep-rupture failures after 2856, 2777, and 1598 h, respectively. Hydrogen permeability coefficients determined after 250 h of rig exposure show that Pyromet 901 had the lowest Phi value, 0.064x10/sup -6/ cm/sup 2//s MPa/sup 1///sup 2/. The next five hairpin tubes, CG-27, Inconel 601, Inconel 718(wd), Inconel 750, and 12RN72(cw) all had Phi values below 0.2x10/sup -6/ more than a decade lower than the design criteria. Based upon its measured high strength and low hydrogen permeation, CG-27 was selected for 3500 h endurance testing at 21 MPa gas pressure and 820/sup 0/C. Results of the high pressure, 21 MPa, CG-27 endurance test demonstrated that the 1.0 vol % C0/sub 2/ dopant is an effective deterrent to hydrogen permeation. The 21 MPa hydrogen gas pressure apparent permeability coefficient at 820/sup 0/C approached 0.1x10/sup -6/ cm/sup 2/sec MPa/sup 1///sup 2/ after 500 hr, the same as the 15 MPa test. Even at this higher gas pressure and comparable permeation rate, CG-27 passed the 3500 hr endurance test without creep-rupture failures. It is concluded that the CG-27 alloy, in the form of thin wall tubing is suitable for Stirling engine applications at 820/sup 0/C and gas pressures up to 21 MPa.

  20. Detection and Repair of Ligament Cracks in a 109mm Thick Superheater Outlet Header

    International Nuclear Information System (INIS)

    Conventional thermal power station boilers are constructed of drums and a series of headers which are interconnected with many hundreds of tubes. Typically feed water enters the boiler at about 250 deg C at a pressure of around 250 bar with steam outlet temperatures of 540 deg C and a pressure of 170 bar. Superheater outlet headers may be subjected to quite arduous conditions during service. Not only are they exposed to high pressure stresses but also to high thermal stresses due to varying thermal gradients through the section thickness particularly at start up and during two shift operation. The area that is exposed to the greatest thermal gradients is the narrow ligament that exists between the tube hole penetrations in the header bore. In the mid the 1980's industry wide surveys found cracking in a large percentage (25-50%) of headers after 15 years of service. Detection and sizing of ligament cracking and estimates of the rate of growth are therefore a major consideration especially in plant that is two shifted. In order to manage the risk both remote visual and ultrasonic inspection are performed during each major unit overhaul. Conclusion: Ultrasonic techniques used for this inspection need to be carefully evaluated with respect to their effectiveness. Conventional pulse echo is capable of detection but using for example a technique such as AS2207 level 1 will not show the defect size. Time of flight diffraction has shown itself to be effective in accurately sizing ligament cracking. However the complex geometry of header ligaments appears to cause a narrowing of the beam with the effect that crack tip responses can be concentrated at the centre of the ligament. Therefore great care needs to be taken during data interrogation because errors in sizing can occur. Wherever possible both 'B' and 'D' scan data should be collected. It appears that the greatest accuracy is obtained with respect to defect growth from the B scan image. With respect to the welding a

  1. Operation of WAGR superheater headers in the creep range

    International Nuclear Information System (INIS)

    The Windscale Advanced Gas Cooled Reactor of the UKAEA is a prototype reactor. A decision to reverse the steam flow in the superheater banks of the heat exchangers resulted in a reversal of duties for the inlet and outlet headers. The original mild steel inlet headers were thus required to operate in the creep range at temperatures of the order of 4500C. A Code approach to the assessment of potential life was found to be inadequate for the purpose of system optimization and so stress-rupture data was analysed by a method which related failure probabilities to the operating parameters of stress and temperature. Whilst one can debate the absolute values of the derived numbers, it is believed that the method gives a feel for the changes of risk with variations in operating conditions. The method offers the considerable advantage of improving communications during inter-disciplinary discussions. New operational limits were established and, as a prudent check on predictions, header performance was monitored using a combination of strain measurement and ultrasonic testing during the annual shutdown. The creep strains developed during service were measured at ambient temperatures at shut-down by replication of orthogonal grids previously scratched on the header surfaces. These data were used to normalize predictive expressions originally derived from laboratory data and strain predictions are now made with some considerable confidence. On a basis of the original failure probability analysis, the rate of development of strain and the results of ultrasonic testing, the need to change the headers appears to be unlikely within the presently planned lifetime of the reactor. (author)

  2. Operation of WAGR superheater headers in the creep range

    International Nuclear Information System (INIS)

    The Windscale Advanced Gas Cooled Reactor of the UKAEA is a prototype reactor. A decision to reverse the steam flow in the superheater banks of the heat exchangers resulted in a reversal of duties for the inlet and outlet headers. The original mild steel inlet headers were thus required to operate in the creep range at temperatures of the order of 4500C. A Code approach to the assessment of potential life was found to be inadequate for the purposes of system optimization and so stress-rupture data were analyzed by a method which related failure probabilities to the operating parameters of stress and temperature. While the absolute values of the derived numbers can be debated, it is believed that the method gives a feel for the changes of risk with variations in operating conditions. The method offers the considerable advantage of improving communications during inter-disciplinary discussions. New operational limits were established and, as a prudent check on predictions, header performance was monitored using a combination of strain measurement and ultrasonic testing during the annual shutdowns. The creep strains developed during service were measured at ambient temperatures at shut-down by replication of orthogonal grids previously scratched on the header surfaces. These data were used to normalize predictive expressions originally derived from laboratory data and strain predictions are now made with some considerable confidence. On a basis of the original failure probability analysis, the rate of development of strain and the results of ultrasonic testing, the need to change the headers appears to be unlikely within the presently planned lifetime of the reactor

  3. Diagnosis of Heat Exchanger Tube Failure in Fossil Fuel Boilers Through Estimation of Steady State Operating Conditions

    International Nuclear Information System (INIS)

    Estimation of operating conditions for fossil fuel boiler heat exchangers is often required due to changes in working conditions, design modifications and especially for monitoring performance and failure diagnosis. Regular heat exchangers in fossil fuel boilers are composed of tube banks through which water or steam flow, while hot combustion (flue) gases flow outside the tubes. This work presents a top-down approach to operating conditions estimation based on field measurements. An example for a 350 MW unit superheater is thoroughly discussed. Integral calculations based on measurements for all unit heat exchangers (reheaters, superheaters) were performed first. Based on these calculations a scheme of integral conservation equations (lumped parameter) was then formulated at the single tube level. Steady state temperatures of superheater tube walls were obtained as a main output, and were compared to the maximum allowable operating temperatures of the tubes material. A combined lumped parameter - CFD (Computational Fluid Dynamics, FLUENT code) approach constitutes an efficient tool in certain cases. A brief report of such a case is given for another unit superheater. We conclude that steady state evaluations based on both integral and detailed simulations are a valuable monitoring and diagnosis tool for the power generation industry

  4. Nonlinear FOPDT Model Identification for the Superheat Dynamic in a Refrigeration System

    DEFF Research Database (Denmark)

    Yang, Zhenyu; Sun, Zhen; Andersen, Casper

    -dependent parameters. The proposed method is firstly tested through a number of numerical examples, and then applied to model the superheat dynamic in a supermarket refrigeration system based on experimental data. As shown in these studies, the proposed method is quite promising in terms of reasonable accuracy, large......An on-line nonlinear FOPDT system identification method is proposed and applied to model the superheat dynamic in a supermarket refrigeration system. The considered nonlinear FOPDT model is an extension of the standard FOPDT model by means that its parameters are time dependent. After the...

  5. Superheater corrosion in biomass-fired power plants: Investigation of Welds

    DEFF Research Database (Denmark)

    Montgomery, Melanie; Carlsen, B; Biede, O;

    2002-01-01

    condense on superheater components. This gives rise to specific corrosion problems not previously encountered in coal-fired power plants. The type of corrosion attack can be directly ascribed to the composition of the deposit and the metal surface temperature. A test superheater was built into the straw-fired...... Masnedø combined heat and power (CHP) plant to investigate corrosion at temperatures higher than that of the actual plant. The highest steam temperature investigated was 570°C. Various alloys of 12-22% chromium content were welded into this test loop. Their corrosion rates were similar and increased...

  6. Solid particle erosion of steels and nickel based alloys candidates for USC steam turbine blading

    Energy Technology Data Exchange (ETDEWEB)

    Cernuschi, Federico; Guardamagna, Cristina; Lorenzoni, Lorenzo [ERSE SpA, Milan (Italy); Robba, Davide [CESI, Milan (Italy)

    2010-07-01

    The main objective of COST536 Action is to develop highly efficient steam power plant with low emissions, from innovative alloy development to validation of component integrity. In this perspective, to improve the operating efficiency, materials capable of withstanding higher operating temperatures are required. For the manufacturing of components for steam power plants with higher efficiency steels and nickel-based alloys with improved oxidation resistance and creep strength at temperature as high as 650 C - 700 C have to be developed. Candidate alloys for manufacturing high pressure steam turbine diaphragms, buckets, radial seals and control valves should exhibit, among other properties, a good resistance at the erosion phenomena induced by hard solid particles. Ferric oxide (magnetite) scales cause SPE by exfoliating from boiler tubes and steam pipes (mainly super-heaters and re-heaters) and being transported within the steam flow to the turbine. In order to comparatively study the erosion behaviour of different materials in relatively short times, an accelerated experimental simulation of the erosion phenomena must be carried out. Among different techniques to induce erosion on material targets, the use of an air jet tester is well recognised to be one of the most valid and reliable. In this work the results of SPE comparative tests performed at high temperatures (550 C, 600 C and 650 C) at different impaction angles on some steels and nickel based alloys samples are reported. (orig.)

  7. 三通集箱过热器压力分布与流量分配的数值模拟%Numerical Simulation on Pressure and Flow Distribution in Superheater with T-junction Headers

    Institute of Scientific and Technical Information of China (English)

    周云龙; 刘袖

    2013-01-01

    To analyze the influence of T-junction structure on flow distribution in superheater with tee-junc-tion(T-junction) headers and subsequently solve the problems of tube burst failure occurring to the superheater, numerical simulations were conducted to a superheater model using Fluent software to study the static pressure distribution and velocity distribution in the superheater, the flow distribution in each branch tube, as well as the fluid velocity and static pressure at each branch inlet. Results show that the fluid near to the tee-structure is low in pressure and high in velocity, while that far away from the region is high in pressure and low in velocity; small vortex only forms in eddy region near T-junction while no vortex in other regions at branch inlet; within the header, the flow in branch tube below the eddy region is relatively low, but that facing the header entrance is the highest; by changing the inlet of the 7th and the 11th tube panel into round shape, the branch flow may be increased significantly.%为了解三通结构对过热器流量分配的影响从而解决三通集箱过热器的爆管问题,利用Fluent软件对过热器模型进行了数值模拟,研究了三通结构集箱过热器内的静压分布、速度分布、各支管流量分配及各支管入口处流体的流速分布和静压分布.结果表明:三通结构附近流体的压力低且速度大,而远离该区域的流体则压力高且速度小;三通中涡流区域的支管入口有小涡流,而其他区域的支管入口没有出现小涡流;集箱内涡流下部的支管流量偏小,正对集箱入口处的支管流量最大;将第7管屏和第11管屏的入口形状改为圆形,改造后支管的流量明显增大.

  8. Failure Analysis of Wall Enclosure Superheater Leakage in 300MW Boiler%300MW锅炉包墙过热器泄漏原因分析

    Institute of Scientific and Technical Information of China (English)

    张广兴; 冯砚厅; 孙涛; 柯浩; 王强

    2013-01-01

    The failure reason for wall enclosure superheater tube leakage in 300 MW boiler was analyzed by boiler structure analysis, macroscopic examination, chemical analysis, metallography analysis and mechanical analysis. The results show that the main reason for the flue gas pipe explosion is wind damage. Then the practical and feasible treatment measures were put forward.%通过对爆管宏观检查,锅炉结构分析,化学分析、金相分析和力学分析等,对300MW锅炉包墙过热器爆管断裂、原因进行了分析.结果表明,爆管主要原因为烟气吹损所致.提出了切实可行的处理措施.

  9. High-Temperature Behavior of a NiCr-Coated T91 Boiler Steel in the Platen Superheater of Coal-Fired Boiler

    Science.gov (United States)

    Chatha, Sukhpal Singh; Sidhu, Hazoor S.; Sidhu, Buta S.

    2013-06-01

    Ni-20Cr coating was deposited on T91 boiler tube steel by high-velocity oxy-fuel (HVOF) process to enhance high-temperature oxidation resistance. High-temperature performance of bare, as well as HVOF-coated steel specimens was evaluated for 1500 h under in the platen superheater zone of coal-fired boiler, where the temperature was around 900 °C. Experiments were carried out for 15 cycles, each of 100-h duration followed by 1-h cooling at ambient temperature. The extent of degradation of the specimens was assessed by the thickness loss and depth of internal corrosion attack. Ni-20Cr-coated steel performed better than the uncoated steel in actual boiler environment. The improved degradation resistance of Ni-20Cr coating can be attributed to the presence of Cr2O3 in the top oxide scale and dense microstructure.

  10. Irradiation of Superheater Test Fuel Elements in the Steam Loop of the R2 Reactor

    International Nuclear Information System (INIS)

    The design, fabrication, irradiation results, and post-irradiation examination for three superheater test fuel elements are described. During the spring of 1966 these clusters, each consisting of six fuel rods, were successfully exposed in the superheater loop No. 5 in the R2 reactor for a maximum of 24 days at a maximum outer cladding surface temperature of ∼ 650 deg C. During irradiation the linear heat rating of the rods was in the range 400-535 W/cm. The diameter of the UO2 pellets was 11.5 and 13.0 mm; the wall thickness of the 20/25 Nb and 20/35 cladding was in every case 0.4 mm. The diametrical gap between fuel and cladding was one of the main parameters and was chosen to be 0.05, 0.07 and 0.10 mm. These experiments, to be followed by one high cladding temperature irradiation (∼ 750 deg C) and one long time irradiation (∼ 6000 MWd/tU), were carried out to demonstrate the operational capability of short superheater test fuel rods at steady and transient operational environments for the Marviken superheater fuel elements and also to provide confirmation of design criteria for the same fuel elements

  11. Single Temperature Sensor Superheat Control Using a Novel Maximum Slope-seeking Method

    DEFF Research Database (Denmark)

    Vinther, Kasper; Rasmussen, Henrik; Izadi-Zamanabadi, Roozbeh;

    2013-01-01

    pressure and a temperature sensor. In this paper we show, through extensive testing, that the superheat or filling of the evaporator can actually be controlled using only a single temperature sensor. This can either reduce commissioning costs by lowering the necessary amount of sensors or add fault...

  12. Superheater fouling in a BFB boiler firing wood-based fuel blends

    NARCIS (Netherlands)

    Stam, A.F.; Haasnoot, K.; Brem, G.

    2014-01-01

    Four different fuel blends have been fired in a 28 MWel BFB. Wood pellets (test 0) were not problematic for about ten years, contrary to a mixture of demolition wood, wood cuttings, compost overflow, paper sludge and roadside grass (test 1) which caused excessive fouling at a superheater bundle afte

  13. Study made of corrosion resistance of stainless steel and nickel alloys in nuclear reactor superheaters

    Science.gov (United States)

    Greenberg, S.; Hart, R. K.; Lee, R. H.; Ruther, W. E.; Schlueter, R. R.

    1967-01-01

    Experiments performed under conditions found in nuclear reactor superheaters determine the corrosion rate of stainless steel and nickel alloys used in them. Electropolishing was the primary surface treatment before the corrosion test. Corrosion is determined by weight loss of specimens after defilming.

  14. Steam separator-superheater with drawing of a fraction of the dried steam

    International Nuclear Information System (INIS)

    This invention concerns a vertical separator-superheater of the steam from a high pressure expansion turbine before it is admitted to an expansion turbine at a lower pressure, by heat exchange with steam under a greater pressure, and drawing of a fraction of the dried steam before it is superheated. Such drawing off is necessary in the heat exchange systems of light water nuclear reactors. Its purpose is to provide a separator-superheater that provides an even flow of non superheated steam and a regular distribution of the steam to be superheated to the various superheating bundles, with a significantly uniform temperature of the casing, thereby preventing thermal stresses and ensuring a minimal pressure drop. The vertical separator-superheater of the invention is divided into several vertical sections comprising as from the central area, a separation area of the steam entrained water and a superheater area and at least one other vertical section with only a separation area of the steam entrained water

  15. Effect of superheat on macrostructure and macrosegregation in continuous cast low-alloy steel slabs

    Science.gov (United States)

    Pikkarainen, T.; Vuorenmaa, V.; Rentola, I.; Leinonen, M.; Porter, D.

    2016-03-01

    The effect of superheat on grain sedimentation and macrosegregation has been investigated using experimental castings of a low-alloyed steel grade. With a high superheat of ∼ 40 °C, the central equiaxed parts of the slabs consisted of randomly oriented fine dendrites but with a low superheat of ∼ 10 °C, coarse globular structures formed. The mean carbon content measured with optical emission spectroscopy was of the order of 15% smaller with coarse globular structures than in fine equiaxed dendritic structures. Electron probe microanalysis of other alloying elements indicates that the negative segregation in the slab central zones is caused by sedimentation of globulites. With superheat in the range ∼ 20 - 40 °C, the equiaxed zone is bordered by a columnar to equiaxed transition (CET) zone. In this region a positive macrosegregation of carbon and other alloying elements was observed. These phenomena are important when considering the through-thickness properties of the slabs and final products.

  16. Clinch River Breeder Reactor Plant steam generator: FEW tube test model post test examination

    International Nuclear Information System (INIS)

    The Steam Generator Few Tube Test (FTT) is part of an extensive testing program being carried out in support of the Clinch River Breeder Reactor Plant (CRBRP) steam generator design. The testing of full-length seven-tube evaporator and three-tube superheater models of the CRBRP design was conducted to provide steady-state thermal/hydraulic performance data to full power per tube and to verify the absence of multi-year endurance problems. The problems encountered with the mechanical features of the FTT model design which led to premature test termination and the results of the post-test examination are described

  17. Compensation of airflow maldistribution in fin-and-tube evaporators

    DEFF Research Database (Denmark)

    Kærn, Martin Ryhl; Tiedemann, Thomas

    2012-01-01

    Compensation of airflow maldistribution in fin-and tube evaporators for residential air-conditioning is investigated with regards to circuitry design and control of individual channel superheats. In particularly, the interlaced and the face split circuitry designs are compared numerically using a...... linear velocity profile and a CFD predicted velocity profile obtained from Kærn (2011d) in dry and wet conditions. The circuitry models are validated experimentally in wet conditions, and for this purpose a test case interlaced evaporator (17.58 kW) was reconstructed in order to become a face split...... evaporator by modifying its U-bend connections. Furthermore, a 14% and 28% blockage of the face split evaporator is studied experimentally with control of individual channel superheats. It is shown that the face split circuitry with compensation gives the best performance in both dry and wet conditions...

  18. Influence of Superheated Steam Temperature Regulation Quality on Service Life of Boiler Steam Super-Heater Metal

    Directory of Open Access Journals (Sweden)

    G. T. Kulakov

    2009-01-01

    Full Text Available The paper investigates influence of change in quality of superheated steam temperature regulations on service life of super-heater metal. А dependence between metal service life and dispersion value for different steel grades has been determined in the paper. Numerical values pertaining to increase of super-heater metal service life in case of transferring from manual regulation to standard system of automatic regulation (SAR have been determined and in case of transferring from standard SAR to improved SAR. The analysis of tabular data and plotted dependencies makes it possible to conclude that any change in conditions of convection super-heater metal work due to better quality of the regulation leads to essential increase of time period which is left till the completion of the service life of a super-heater heating surface.

  19. Damage at a superheater in a combined cycle plant due to insufficient phase separation in the drum; Schaden an einem Ueberhitzer einer GuD-Anlage durch unzureichende Phasentrennung in der Trommel

    Energy Technology Data Exchange (ETDEWEB)

    Reichel, H.H. [GB PowerTech e.V., Essen (Germany). Werkstofflabor; Weiher, R. [VGB PowerTech e.V., Essen (Germany); Gebert, H. [Bewag Aktiengesellschaft, Berlin (Germany). Abt. EZ; Hopp, G. [Bewag Aktiengesellschaft, Berlin (Germany). Abt. EEB; Huehn, B. [Bewag Aktiengesellschaft, Berlin (Germany). Abt. EZP

    2001-07-01

    In spring 1999 severe wear was detected at the internal wall of finned tubes in the first of two HRSG of the newly constructed combined cycle plant of the Mitte station of Bewag. The damage occurred at the entrance of the HP superheater and resulted in wall fractures. The laboratory examination revealed insufficient phase separation in the drum resulting in boiler water entering the superheater tubes. Due to the concentration of water constituents this process led to increased hot water oxidation. The root cause identified was confirmed by an examination of the drum/demister design. As precautionary measure the active area of the demister was enlarged by 50% and the inspection possibilities in the critical area were improved. (orig.) [German] Im ersten von zwei Abhitzekesseln der neu errichteten GuD-Anlage im Heizkraftwerk Mitte der Bewag sind nach relativ kurzer Betriebszeit starke Abzehrungen der Innenwand der Rippenrohre im Eintrittsbereich des HD-Ueberhitzers aufgetreten, die zu Wanddurchbruechen gefuehrt haben. Das Ergebnis von Laboruntersuchung wies hin auf eine mangelhafte Phasentrennung in der Trommel und dadurch Eintrag von Kesselwasser in die Ueberhitzerrohre. Aufgrund der sich aufkonzentrierenden Wasserinhaltstoffe hat dieser Vorgang zu einer katastrophal verstaerkten Heisswasseroxidation gefuehrt. Die ermittelte Schadensursache wurde durch Begutachtung der Trommel-/Demisterauslegung bestaetigt. (orig.)

  20. Analysis of High-temperature Boiler Tube Failure for T91 &T22

    Institute of Scientific and Technical Information of China (English)

    SHU Guo-gang; DING Hui; ZHAO Yan-fen; XUE Fei; ZHAO Ling-song; ZHANG Lu; LIU Jiang-nan; WANG Zheng-pin

    2004-01-01

    The tube failures took place frequently in the superheater of 2x600MW units in a power plant. According to the condition of tube failures, the mechanical property and microstructure on running and failed tubes were tested and evaluated. The chemical composition and structure phase of inner oxide scale and deposit inside of the tubes were examined.The fractured surfaces of failed tube samples were observed. And the material examination was performed for original tube steels SA213-T91 and SA213-T22. The results show that raw materials of SA213-T91 and SA213-T22 tube in superheater are qualified. Besides, the characteristics of the SA213-T91 and SA213-T22 tube failure are typical short-term overheated rupture. The rupture temperature is located between two phase Ac1 ~ Ac3 of the two steels. It is recognized that putting SA213-T22 tubes in operation under the condition of long-term over heating causes the rupture of SA213-T91 and SA213-T22.

  1. Microstructural characteristics of in situ Mg2Si/Al-Si composite by low superheat pouring

    Directory of Open Access Journals (Sweden)

    Wu Xiaofeng

    2013-09-01

    Full Text Available To control the morphology and size of the primary and eutectic Mg2Si phases in in situ Mg2Si/Al-Si composite and achieve a feasible and reliable technique to produce appropriate feedstock for the thixo-casting and rheo-casting of this type of material, three Al-Si matrix composites reinforced by 5wt.%, 9wt.% and 17wt.% Mg2Si with hypoeutectic, eutectic and hypereutectic compositions were prepared by the low superheat pouring (LSP process. The effects of the pouring temperature (superheat on the morphology and size distribution of primary phases (primary α-Al and Mg2Si, binary (α-Al + Mg2Si eutectic cell and eutectic Mg2Si were investigated. The experimental results show that low pouring temperature (superheat not only refines the grain structure of the primary α-Al and binary (α-Al + Mg2Si eutectic cell in three composites and promotes the formation of more non-dendritic structural semi-solid metal (SSM slurry of these phases; but also refines the primary and eutectic Mg2Si phases, which seems to be attributed to the creation of an ideal condition for the nucleation and the acquisition of a high survival of nuclei caused by the LSP process.

  2. The Candidate

    OpenAIRE

    Osborn, John C

    2013-01-01

    ABSTRACT   The Candidate is an attempt to marry elements of journalism and gaming into a format that both entertains and educates the player. The Google-AP Scholarship, a new scholarship award that is given to several journalists a year to work on projects at the threshold of technology and journalism, funded the project. The objective in this prototype version of the game is to put the player in the shoes of a congressional candidate during an off-year election, specificall...

  3. Clinch River Breeder Reactor Plant Steam Generator Few Tube Test model post-test examination

    International Nuclear Information System (INIS)

    The Steam Generator Few Tube Test (FTT) was part of an extensive testing program carried out in support of the Clinch River Breeder Reactor Plant (CRBRP) steam generator design. The testing of full-length seven-tube evaporator and three-tube superheater models of the CRBRP design was conducted to provide steady-state thermal/hydraulic performance data to full power per tube and to verify the absence of multi-year endurance problems. This paper describes the problems encountered with the mechanical features of the FTT model design which led to premature test termination, and the results of the post-test examination. Conditions of tube bowing and significant tube and tube support gouging was observed. An interpretation of the visual and metallurgical observations is also presented. The CRBRP steam generator has undergone design evaluations to resolve observed deficiences found in the FFTM

  4. Influence of the original structure and aging temperature and time on the formation of sigma-phase in tubes of 12Kh18N12T steel

    International Nuclear Information System (INIS)

    An investigation was made of 32x6 mm steam superheater tubes of 12Kh18N12T steel containing 0.09% C and 0.50% Ti. It was established that the aging temperature, the length of the hold at the selected temperature, and the grain size of the original metal influence the formation of σ-phase. The microhardness of specimens taken from the tubes before and after straightening in relation to the investigated factors is shown. It is shown that an increase in aging temperature and time in combination with a coarse-grained structure of steam superheater tubes of 12Kh18N12T steel leads to precipitation of σ-phase in the grain boundaries, which may cause embrittlement of the tube metal in service of it

  5. Effect of chemical composition and superheat on macrostructure of high Cr white iron castings

    Energy Technology Data Exchange (ETDEWEB)

    Dogan, Omer N.

    2005-08-01

    White cast irons are frequently used in applications requiring high wear resistance. High Cr white cast irons have a composite microstructure composed of hard (Fe,Cr)7C3 carbides in a steel matrix. Previous research has indicated that the equiaxed region of these high Cr white iron castings is much more wear resistant under high stress abrasive conditions than the columnar region, when the carbides are oriented perpendicular to the wear surface. In the present study, the effect of both the chemical composition, particularly carbon content, and the pouring superheat of the melt on the macrostructure of high Cr white iron castings is investigated.

  6. Thermal Behavior of Floor Tubes in a Kraft Recovery Boiler

    Energy Technology Data Exchange (ETDEWEB)

    Barker, R.E.; Choudhury, K.A.; Gorog, J.P.; Hall, L.M.; Keiser, J.R.; Sarma, G.B.

    1999-09-12

    The temperatures of floor tubes in a slope-floored black liquor recovery boiler were measured using an array of thermocouples located on the tube crowns. It was found that sudden, short duration temperature increases occurred with a frequency that increased with distance from the spout wall. To determine if the temperature pulses were associated with material falling from the convective section of the boiler, the pattern of sootblower operation was recorded and compared with the pattern of temperature pulses. During the period from September, 1998, through February, 1999, it was found that more than 2/3 of the temperature pulses occurred during the time when one of the fast eight sootblowers, which are directed at the back of the screen tubes and the leading edge of the first superheater bank, was operating.

  7. Comparison of thermal fatigue behaviour of ASTM A 213 grade T-92 base and weld tubes

    International Nuclear Information System (INIS)

    Super-heater tubes are subjected to alternate heating and cooling in power plants causing them to crack and eventually fail. This phenomenon is referred to as 'thermal fatigue.' In this paper, a laboratory simulation for reproducing the thermal fatigue phenomenon is developed to determine the number of cycles necessary before failure occurs in super-heater tubes. The temperature and strain distributions along the specimen were computed theoretically using ANSYS software for the applied temperature condition. The thermal fatigue test was conducted for both base and shielded metal arc (SMA) welded tubes separately and both passed in the non-destructive tests. These tubes were subjected to thermal cycles from 800 .deg. C (accelerated temperature) to room temperature. Oxy-acetylene heating setup was utilized as a heating source, and a water bath was utilized for quenching purposes. The tests were carried out until open cracks were identified. Surface cracks were identified in the base and weld tubes after 90 and 60 cycles respectively. This study reveals that heating and cooling cause thermal fatigue, initiate cracks in the tubes

  8. The development and application of overheating failure model of FBR steam generator tubes

    International Nuclear Information System (INIS)

    The following items have been studied to evaluate overheating failure of FBR steam generator heat transfer tubes: 1) To establish a structural integrity analysis method, 2) To improve and validate blow down analytical method, 3) To quantitatively validate the entire overheating analysis model by sodium water reaction data. Based on the above studies, the analytical method was applied to PFR superheater leak event and the Monju steam generator accidental analysis. The followings were quantitatively shown through the analysis: 1. The most important cause that multi-tube failure occurred in the 1987 PFR superheater-2 leak is that the superheater did not equip a fast steam dump system at the time of the leak event. 2. Overheating failure will not occur under any operational conditions of Monju in both steady state and transient phases such as water/steam blow-down. 3. Although safety margin becomes small when the water/steam flow rate becomes small during the blow-down, the modification of the plant such as hastening blow-down by equipping more relief valves will drastically improve the safety margin. (J.P.N.)

  9. 锅炉过热器管爆管失效分析%Failure Analysis on Superheater Tube of Boiler

    Institute of Scientific and Technical Information of China (English)

    程宏辉; 李超; 沈美华; 祝新伟; 潘金平; 沈平

    2015-01-01

    调查了规格为φ32 mmn×4 mm过热器管发生爆裂的事故,通过力学性能分析、化学成分检测、金相分析及扫描电镜分析等方法对炉管爆裂原因进行了分析.最终发现失效的原因为炉管的钢材使用错误,使得炉管强度不足,最终导致炉管的爆裂.

  10. Prediciton of the remaining service life of superheater and reheater tubes in coal-biomass fired power plants

    OpenAIRE

    Asgaryan, Mohammad

    2013-01-01

    As a result of concern about the effects of CO2 emssions on the global warming, there is increasing pressure to reduce such emissions from power generation systems. The use of biomass co-firing with coal in conventional pulverised fuel power plants has provided the most immediate route to introduce a class of fuel that is regarded as both sustainable and carbon neutral as it produces less net CO2 emissions. In the future it is anticipated that increased levels of biomass will be required to u...

  11. 后屏过热器爆管事故原因分析%Analysis of Platen Superheater Tube Failure

    Institute of Scientific and Technical Information of China (English)

    李煜峰

    2007-01-01

    介绍了DG1025/18.2-Ⅱ型锅炉设备概况,针对一起后屏过热器爆管事故,提出测试分析方法,给出测试分析结果,并根据现场实际情况制定了预防措施,从而保证了锅炉的安全稳定运行.

  12. Study on Failure Analysis of Superheater Tube%过热器管的失效研究

    Institute of Scientific and Technical Information of China (English)

    邱启明; 江国栋

    2014-01-01

    通过金相、显微硬度、扫描电镜和能谱仪进行观察,对火电厂中过热器管的失效进行分析.研究表明:过热器管的过早失效是由于蠕变孔洞的形成和微裂纹的扩展而造成的.短期超温失效属于穿晶断裂;而长期超温失效属于沿晶和穿晶混合断裂.

  13. Whole system and estimation technique of overall heat transfer coefficient of evaporator and superheater

    International Nuclear Information System (INIS)

    A hybrid diagnostic agent system is developed to detect and identify early an anomaly that happens in the fast-breeder reactor 'Monju'. The system outputs a diagnostic result by integrating the results of diagnosis by four diagnostic software agents. They are (1) an estimation agent of overall heat transfer coefficient of evaporator and superheater, (2) a state identification agent based on SVM (Support Vector Machine), (3) an anomaly detection agent by WT (Wavelet Transformation), and (4) a CBR (Case-Based Reasoning) agent using several attributes in both time and frequency domain. This paper describes the whole system and the estimation technique of overall heat transfer coefficient by simple physical models from 'Monju' process signals. (author)

  14. Main causes of failures in critical radius bends of fuel power plant superheater

    International Nuclear Information System (INIS)

    In this paper the authors made a resume of study carried out by materials laboratory of Centro de Estudios Aplicados al Desarrollo Nuclear. Establishment of the causes of the simultaneous failures and after cracking occurred in the neutral zone Of critical radius bends locating in high pressure superheater of fuel power plant long two years. Authors arrived to the conclusions that the main cause of simultaneously failures in the critical radius bends was the high sulfur content in the Steel of these bends and observed internal cracking in the plastic deformed zone (strike), made during construction of bends in the factory. These works was too Helpful in taking decision for changes all critical radiuses bends and avoid the decrease of generate electrical energy

  15. Evaporator Superheat Control With One Temperature Sensor Using Qualitative System Knowledge

    DEFF Research Database (Denmark)

    Vinther, Kasper; Hillerup Lyhne, Casper; Baasch Sørensen, Erik;

    2012-01-01

    This paper proposes a novel method for superheat control using only a single temperature sensor at the outlet of the evaporator, while eliminating the need for a pressure sensor. An inner loop controls the outlet temperature and an outer control loop provides a reference set point, which is based...... optimal filling of the evaporator, with only one temperature sensor. No a priori model knowledge was used and it is anticipated that the method is applicable on a wide variety of refrigeration systems....... on estimation of the evaporation pressure and suitable reference logic. The pressure is approximated as being linear and proportional to the opening degree of the expansion valve. This gain and the reference logic is based on calculation of the variance in the outlet temperature, which have shown to...

  16. PREDICTION OF OXIDE SCALE EXFOLIATION IN STEAM TUBES

    Energy Technology Data Exchange (ETDEWEB)

    Sabau, Adrian S [ORNL; Wright, Ian G [ORNL

    2010-01-01

    Numerical simulation results are presented for the prediction of the likelihood of oxide scale exfoliation from superheater tubes. The scenarios considered involved alloys T22, TP347H, and TP347HFG subjected to a simplified operating cycle in a power plant generating supercritical steam. The states of stress and strain of the oxides grown in steam were based solely on modeling the various phenomena experienced by superheater tubes during boiler operation, current understanding of the oxidation behavior of each alloy in steam, and consideration of operating parameters such as heat flux, tube dimensions, and boiler duty cycle. Interpretation of the evolution of strain in these scales, and the approach to conditions where scale failure (hence exfoliation) is expected, makes use of the type of Exfoliation Diagrams that incorporate various cracking and exfoliation criteria appropriate for the system considered. In these diagrams, the strain accumulation with time in an oxide is represented by a strain trajectory derived from the net strain resulting from oxide growth, differences in coefficients of thermal expansion among the components, and relaxation due to creep. It was found that an oxide growing on a tube subjected to routine boiler load cycling conditions attained relatively low values of net strain, indicating that oxide failure would not be expected to occur during normal boiler operation. However, during a boiler shut-down event, strains sufficient to exceed the scale failure criteria were developed after times reasonably in accord with plant experience, with the scales on the ferritic steel failing in tension, and those on the austenitic steels in compression. The results presented illustrate that using this approach to track the state of strain in the oxide scale through all phases of boiler operation, including transitions from full-to-low load and shut-down events, offers the possibility of identifying the phase(s) of boiler operation during which oxide

  17. Manufacture technique of semi-solid slurry of hypoeutectic Al-Si alloy by low superheat pouring and weak electromagnetic stirring

    Institute of Scientific and Technical Information of China (English)

    LIU Zheng; MAO Wei-ming; ZHAO Zheng-duo

    2006-01-01

    The semi-solid slurry of hypoeutectic Al-Si alloy was manufactured by low superheat pouring and weak electromagnetic stirring. The effects of pouring temperature and stirring power on the semi-solid slurry making process were investigated. The results indicate that the semi-solid slurry to satisfy rheocasting requirement can be made by a combination of low superheat pouring and weak electromagnetic stirring. The pouring temperature (or superheat) and the stirring power significantly affect the morphology and the size of primary α-Al, while there is no obvious effect of the stirring time on primary α-Al. Compared with the samples made by low superheat pouring without stirring, the nucleation rate,particle morphology and grain size of primary α-Al in A356 Al alloy are markedly improved by a process of applying both low superheat pouring and weak electromagnetic stirring. Under the condition of weak electromagnetic stirring applied, the pouring temperature with low superheat can be equivalerttly to reach the effectiveness obtained from the even lower pouring temperature without stirring.

  18. Research on semi-solid slurry of a hypoeutectic Al-Si alloy prepared by low superheat pouring and weak electromagnetic stirring

    Institute of Scientific and Technical Information of China (English)

    2006-01-01

    The semi-solid slurry of a hypoeutectic Al-Si alloy was manufactured by low superheat pouring and weak electromagnetic stirring. The effects of pouring temperature and stirring power on the semi-solid slurry were investigated. The results indicated that the semi-solid slurry to satisfy rheocasting can be manufactured by low superheat pouring and weak electromagnetic stirring. The pouring temperature (or superheat) and the stirring power remarkably affected the morphology of primary α-Al and the size of primary α-Al, and there is no obvious effect of stirring time on primary α-Al. Compared with the samples made by low superheat pouring with no stirring, the nucleation rate, particle morphology and grain size of primary α-Al in A356 were markedly improved by low superheat pouring and weak electromagnetic stirring. On the condition of weak electromagnetic stirring, the pouting temperature with low superheat can be suitably raised to reach the effectiveness obtained from the lower pouring temperature without stirring.

  19. Experimental research on heat transfer to liquid sodium and its incipient boiling wall superheat in an annulus

    Institute of Scientific and Technical Information of China (English)

    2006-01-01

    Liquid sodium is mainly used as a cooling fluid in the liquid metal fast breeder reactor (LMFBR), whose heat transfer, whether convective heat transfer or boiling heat transfer, is different from that of water. So it is important for both normal and accidental operations of LMFBR to perform experimental research on heat transfer to liquid sodium and its boiling heat transfer. This study deals with heat transfer with high temperature (300-700℃) and low Pe number (20~70) and heat transfer with low temperature (250~270℃) and high Pe number (125~860), and its incipient boiling wall superheat in an annulus. Research on heat transfer involves theoretical research and experiments on heat transfer to liquid sodium. It also focuses on the theoretical analysis and experimental research on its incipient boiling wall superheat at positive pressure in an annulus. Semiempirical correlations were obtained and they were well coincident with the experimental data.

  20. Superheater corrosion improved utilization of gained experience; Oeverhettarkorrosion - baettre utnyttjande av projektresultat

    Energy Technology Data Exchange (ETDEWEB)

    Nystroem, Olle; Ehrstedt, Thomas [Carl Bro Energikonsult AB, Stockholm (Sweden); Kjoerk, Anders [S.E.P. Scandinavian Energy Projects AB (Sweden)

    2004-01-01

    Superheater corrosion has been a problem in many biofuelled district heating and cogeneration plants. Even if this 'disease' easily can be diagnosed and the immediate mechanisms about how and why it develops are relatively well known, the underlying causes, which the individual plant owner has to live with, represent a diversity of complex causes and effects. The conditions may vary from plant to plant, a fact, which would normally represent a difficulty with regard to a full-fledged analysis, but often some common elements can be identified for a prefatory analysis. Analysis would be facilitated with access to a tool enabling a systematic gathering of plant operation data. Vaermeforsk (Thermal Engineering Research Institute) and its Chemical and Material Technology group have discussed the need of a database, which combines the requirements among plant owners/operators on one side and researchers/developers on the other. In this report a database meeting these requirements is presented. The database is based on Access 2000 and made available at the Vaermeforsk homepage (www.varmeforsk.se). It is a database where any piece of information is found in one specific site or memory within it. These sites/memories taking the form of tables are linked to each other. To be able to characterise a specific plant/boiler and specify the conditions of interest, detailed information is required. The database input is based on information that seems relevant with regard to output and which also can be quantified with reasonable effort. Data have been structured in five areas/domains covering: the plant, the superheater, the case(report), the material and the fuel. A case description/form, which constitutes the core of the database, is presented in the table 'Fall' (Case), where information/data related to steam data, standard fuel mix, deposit and flue gas analysis etc. plus information about corrosion for a certain superheater in a specific plant are

  1. An experimental investigation of flow patterns and liquid entrainment in a horizontal-tube evaporator

    Science.gov (United States)

    Barnhart, John Steven

    An experimental study of two-phase flow patterns and droplet entrainment in a horizontal-tube evaporator was conducted. Measurements were made with serpentine aluminum and glass evaporators with geometries typical of those used for domestic refrigeration. The refrigerant in the majority of tests was R134a, which will replace R12 for refrigeration and automotive air-conditioning in 1995. The phenomenon of primary interest was the nonequilibrium transport of droplets within superheated vapor at the evaporator exit. Of particular concern were substantial variations in the liquid rate with time, and corresponding fluctuations in exit temperature. These variations are due to the formation of slugs which rapidly transport a surplus of liquid toward the exit. A flow loop was constructed to circulate oil-free refrigerant through the evaporator under widely varying conditions. Liquid carry over (expressed as a dimensionless entrained mass fraction, EMF) was measured as a function of inlet quality, heat flux, mass flux, and exit superheat. A laser-based phase/Doppler particle analyzer was used to measure droplet diameters and velocities at the evaporator exit. Tests with three refrigerants over wide ranges of operating conditions revealed time-averaged EMF's of no more than 0.1 percent. Analysis of variance showed exit superheat to have the strongest effect, followed by mass flux, inlet quality, and heat flux. Time-averaged EMF's varied with operating conditions by several orders of magnitude, decreasing with increasing superheat level (due to lower entrainment rates near the exit and more rapid droplet vaporization) and mass flux and inlet quality (due to reduced slug formation). The incidence of slug flow and its effect on evaporator exit conditions were documented in time-resolved experiments, using techniques such as auto- and cross-correlation and Fourier transform. Time-resolved EMF's as high as one percent were observed, as well as sharp reductions in exit superheat

  2. Gastrostomy Tube (G-Tube)

    Science.gov (United States)

    ... endoscope (a thin, flexible tube with a tiny camera and light at the tip) inserted through the ... Nemours Foundation, iStock, Getty Images, Corbis, Veer, Science Photo Library, Science Source Images, Shutterstock, and Clipart.com

  3. Ear tube insertion

    Science.gov (United States)

    Myringotomy; Tympanostomy; Ear tube surgery; Pressure equalization tubes; Ventilating tubes; Ear infection - tubes; Otitis - tubes ... trapped fluid can flow out of the middle ear. This prevents hearing loss and reduces the risk ...

  4. Coiled tubing

    International Nuclear Information System (INIS)

    Oil and gas wells that flow on initial completion eventually reach a condition of liquid loading that kills the wells. This results form declining reservoir pressure, decreased gas volume (velocity), increased water production and other factors that cause liquids to accumulate at the bottom of the well and exert back pressure on the formation. This restricts or in some cases prevents fluid entry into the wellbore form the formation. Flowing production can be restored or increased by reducing surface backpressure, well bore stimulation, pressure maintenance or by installing a string of smaller diameter tubing. This paper reports on installation (hanging off) of a concentric string of coiled tubing inside existing production tubing which is an economically viable, safe, convenient and effective alterative for returning some of these liquid loaded )logged-up) wells to flowing status

  5. Ear Tubes

    Science.gov (United States)

    ... of the ear drum or eustachian tube, Down Syndrome, cleft palate, and barotrauma (injury to the middle ear caused by a reduction of air pressure, ... specialist) may be warranted if you or your child has experienced repeated ... fluid in the middle ear, barotrauma, or have an anatomic abnormality that ...

  6. Factors in the selection of broiler tube materials for a civil fast reactor

    International Nuclear Information System (INIS)

    This paper briefly considers some of the factors which must be balanced in the selection of a boiler tube material for a Civil Fast Reactor. The merits and possible demerits of low alloy ferritic steels and the austenitic Alloy 800 are compared with respect to waterside corrosion resistance, mechanical properties, fabrication and weldability and possible effects of exposure to the sodium environment under normal and fault conditions. It is pointed out that although there is operational experience of most of the materials in boiler superheater applications there is little or none in evaporative regimes. (author)

  7. Failure analysis of austenitic stainless steel tubes in a gas fired steam heater

    International Nuclear Information System (INIS)

    Highlights: ► 304H stainless steel is more susceptible to caustic SCC compared to SA335 alloy steel. ► Caustic attacks the protective layer of stainless steel superheater tubes. ► Sigma phase formation at the weld zone causes crack initiation in fired heater tubes. -- Abstract: Carryover of caustic soda (NaOH) in the steam path caused catastrophic failure of superheater 304H stainless steel tubes in a gas fired heater and led to an unexpected shutdown after just 5 months of continuous service following the start of production. The cause of the failure was studied, with a focus on the effect of caustic embrittlement on stress corrosion cracking (SCC). The cracks were examined at the seam weld, heat affected zone (HAZ), and U-bend areas. Hardness was measured for the base metal, HAZ, and weld metal, and microstructures were examined using optical microscopy and scanning electron microscopy (SEM). Crack initiation is attributed to gouging on the precipitated carbide at the HAZ and also the formation of sigma phase in the weld metal, as shown by energy dispersive X-ray (EDX) analysis. In addition, cracking was propagated by caustic embrittlement because of residual stresses and hammering. Finally, the characteristic feature of fracture was illustrated by SEM fractography, and consists mostly of intergranular SCC and some quasi-cleavage transgranular.

  8. Effect of electrolysis superheat degree on anticorrosion performance of 5Cu/(10NiO-NiFe2O4) cermet inert anode

    Institute of Scientific and Technical Information of China (English)

    2007-01-01

    5Cu/(10NiO-NiFe2O4) cermet inert anodes were prepared by cold-pressing and sintering process, and the effect of superheat degree of melting K3AIF6-Na3AlF6-AlF3 on their anticorrosion performance was studied under electrolysis conditions. The results show that, the fluctuation of cell becomes small with increasing of superheat degree, which is helpful to inhibit the formation of cathodic encrustation; the concentration of impurities from inert anode in bath goes up to certain degree, but it is far smaller than those in traditional high-temperature bath. Increasing the superheat degree of melting K3AlF6-Na3AlF6-AlF3 has unconspicuous effect on the contents of impurities in cathodic aluminum. The total mass fractions of Fe, Ni and Cu in aluminum are 15.38% and15.09% respectively under superheat degree of 95 and 195 ℃C. From micro-topography of anode used view, increasing the superheat degree can aggravate corrosion of metal Cu in inert anode, and has negative influence on electrical conductivity of electrode to some extent.

  9. On-Line Life Monitoring Technique for Tube Bundles of Boiler High-Temperature Heating Surface

    Institute of Scientific and Technical Information of China (English)

    Yang Dong; Wang Zhongyuan

    2005-01-01

    High-temperature heating surface such as superheater and reheater of large-sized utility boiler all experiences a relatively severe working conditions. The failure of boiler tubes will directly impact the safe and economic operation of boiler. An on-line life monitoring model of high-temperature heating surface was set up according to the well-known L-M formula of the creep damages. The tube wall metal temperature and working stress was measured by on-line monitoring, and with this model, the real-time calculation of the life expenditure of the heating surface tube bundles were realized. Based on the technique the on-line life monitoring and management system of high-temperature heating surface was developed for a 300 MW utility boiler. An effective device was thus suggested for the implementation of the safe operation and the condition-based maintenance of utility boilers.

  10. Electron tube

    Energy Technology Data Exchange (ETDEWEB)

    Suyama, Motohiro (Hamamatsu, JP); Fukasawa, Atsuhito (Hamamatsu, JP); Arisaka, Katsushi (Los Angeles, CA); Wang, Hanguo (North Hills, CA)

    2011-12-20

    An electron tube of the present invention includes: a vacuum vessel including a face plate portion made of synthetic silica and having a surface on which a photoelectric surface is provided, a stem portion arranged facing the photoelectric surface and made of synthetic silica, and a side tube portion having one end connected to the face plate portion and the other end connected to the stem portion and made of synthetic silica; a projection portion arranged in the vacuum vessel, extending from the stem portion toward the photoelectric surface, and made of synthetic silica; and an electron detector arranged on the projection portion, for detecting electrons from the photoelectric surface, and made of silicon.

  11. Neutron tubes

    Science.gov (United States)

    Leung, Ka-Ngo; Lou, Tak Pui; Reijonen, Jani

    2008-03-11

    A neutron tube or generator is based on a RF driven plasma ion source having a quartz or other chamber surrounded by an external RF antenna. A deuterium or mixed deuterium/tritium (or even just a tritium) plasma is generated in the chamber and D or D/T (or T) ions are extracted from the plasma. A neutron generating target is positioned so that the ion beam is incident thereon and loads the target. Incident ions cause D-D or D-T (or T-T) reactions which generate neutrons. Various embodiments differ primarily in size of the chamber and position and shape of the neutron generating target. Some neutron generators are small enough for implantation in the body. The target may be at the end of a catheter-like drift tube. The target may have a tapered or conical surface to increase target surface area.

  12. Straightening tubes

    International Nuclear Information System (INIS)

    Hexagonal wrapper tubes, especially for nuclear reactor core sub-assemblies, may suffer from unacceptable bow as a result of welding wear pads to the wrapper and heat treatment. Straightening of the bow is effected by a method wherein at each of a series of axially spaced locations the faces or vertices of the tube are measured relative to a reference to determine the direction of bow at the locations. From these measurements, the appropriate axial locations for the application of corrective loading can be determined, whereby by application of the loading at a selected face or vertex for such measurements the bow is reduced. Such loading, by an actuator, can be repeated at the locations until the bow is reduced to within tolerances. (author)

  13. Experimental study of post-dryout with R-134a upward flow in vertical smooth tube and rifled tubes

    International Nuclear Information System (INIS)

    correlation used the heat transfer enhancement ratio of the rifled tube against the smooth tube and two geometry parameters, {din/e, {πdin/4w. The heat transfer coefficients of the smooth tube which were equivalent to the rifled tube conditions were calculated by the correlation for smooth tube. The correlation for the rifled tube predicted the wall temperature of the present experiments within ±10% . The phenomenological model for the prediction of wall temperature in the rifled tubes was also developed using simple superposition of heat transfer for both evaporation and superheat regions, assuming thermal equilibrium. In order to calculate the wall temperature in the superheated region, the heat transfer coefficients calculated by the friction-heat transfer analogy approach were used in the heat transfer equation with the superheated vapor temperature calculated by simple heat balance. For the evaporation region, the friction-heat transfer analogy approach and the correlation of Baumeister were used for the heat transfer calculation from the wall to vapor and from the wall to droplets, respectively, and the vapor saturated temperature was used as the vapor temperature. This model predicted the wall temperature of the rifled tube within +15%, -7%

  14. Damage distribution and remnant life assessment of a super-heater outlet header used for long time

    Energy Technology Data Exchange (ETDEWEB)

    Hiroyuki, Okamura [Science Univ. of Tokyo (Japan); Ryuichi, Ohotani [Kyoto Univ. (Japan); Kazuya, Fujii [Japan Power Engineering and Inspection Corp., Tokyo (Japan); Masashi, Nakashiro; Fumio, Takemasa; Hideo, Umaki; Tomiyasu, Masumura [Ishikawajima-Harima Heavy Industries Co. Ltd., Tokyo (Japan)

    1998-11-01

    This paper presents the results of investigation on evaluating damage distribution to base metals and welded joints in the thickness direction and evaluate damage on ligaments. Thick wall tested sample was the superheater outlet header component long term serviced in high pressure and temperature condition in thermal power plant. The simulate unused steel of component material was made from sample by suitable heat treatment, and the extent of damage was assessed based on a comparison of nondestructive and destructive test results between simulate unused and aged samples. Damage evaluation was also made by FEM structural stress analysis. (orig./MM)

  15. Simulation analysis of static and dynamic characteristics of once-through steam generator in concentric annuli tube

    Institute of Scientific and Technical Information of China (English)

    ZHANG Wei; BIAN Xin-qian; XIA Guo-qing

    2006-01-01

    The once-through steam generator (OTSG) in concentric annuli tube is a new type of steam generator which applies double side to transfer heat. The heat flux between the water of centric tube, outside annuli tube and that of annulus channel is assumed to be equal, and then the steam generator's model is built by lumped parameters with moving boundary. In the basis of the built model, static and dynamic characteristics are analyzed.The static characteristics are proved by experiment results in a 19-tube once-through steam generator of Babcock & Wilcox. The characteristics that the lengths of three regions (subcooled region, nucleate boiling region, superheat region) change with power can be explained by theory analysis. The dynamic characteristics accord with the heat and hydraulics and the results of analysis according to the mechanism.

  16. photomultiplier tubes

    CERN Multimedia

    photomultiplier tubes. A device to convert light into an electric signal (the name is often abbreviated to PM). Photomultipliers are used in all detectors based on scintillating material (i.e. based on large numbers of fibres which produce scintillation light at the passage of a charged particle). A photomultiplier consists of 3 main parts: firstly, a photocathode where photons are converted into electrons by the photoelectric effect; secondly, a multiplier chain consisting of a serie of dynodes which multiply the number of electron; finally, an anode, which collects the resulting current.

  17. photomultiplier tube

    CERN Multimedia

    photomultiplier tubes. A device to convert light into an electric signal (the name is often abbreviated to PM). Photomultipliers are used in all detectors based on scintillating material (i.e. based on large numbers of fibres which produce scintillation light at the passage of a charged particle). A photomultiplier consists of 3 main parts: firstly, a photocathode where photons are converted into electrons by the photoelectric effect; secondly, a multiplier chain consisting of a serie of dynodes which multiply the number of electron; finally, an anode, which collects the resulting current.

  18. Analysis of T91 Steel Pipe Bursting at High Temperature Superheater in Supercritical Boiler%超临界锅炉高温过热器T91钢管爆管分析

    Institute of Scientific and Technical Information of China (English)

    钟万里; 盘荣旋

    2009-01-01

    通过化学成分、显微组织、力学性能、硬度和内壁沉积物检查等手段对某电厂超临界锅炉高温过热器出口T91钢管爆裂的原因进行了分析.结果表明:由于该钢管内壁氧化皮脱落堆积,管内蒸汽流通面积减小,造成了钢管过热,从而引起了钢管在薄弱区域爆裂失效.%For the T91 steel pipe bursting at the high temperature superheater exports in a supercritical power plant boiler, some tests had been completed such as chemical composition analysis, mierostructure examination, me-chanical properties testing, hardness and deposit inspection. The results showed that the oxidation of the tube in the boiler fell off and amassed, the circulation area og steam in pipe reduced, and caused the overheating , all those caused the pipe failured in the weak region.

  19. D型动力锅炉过热器管失效原因分析%FAILURE CAUSE ANALYSIS ON SUPERHEATER PIPES OF D TYPE POWER BOILER

    Institute of Scientific and Technical Information of China (English)

    周焕英

    2015-01-01

    Comprehensive performance tests on the superheater pipes of power boiler B in Qilu Olefin Complex including such as macro morphology, components of the surface fouling and over-all properties of the material were made.The results showed that machine direction cracks of the No.1 and No.2 superheater pipes were the material developing creep cracks due to the performance worsen caused by the long time superheat, and surface fouling corrosion which could reduce the pipe wall thickness aggravating the crack speed of the superheater pipes.%通过对烯烃厂动力锅炉B炉过热器管进行宏观形貌、表面垢物成分、材料综合性能检验得知,该锅炉第一、二过热器管发生纵向开裂主要是由于其长期处于过热状态工作造成材料性能恶化所致的蠕变开裂;过热器管表面结垢物腐蚀导致的管壁减薄则加剧了其开裂的速度。

  20. Experimental investigation of vortex tube refrigerator with a divergent hot tube

    Energy Technology Data Exchange (ETDEWEB)

    Chang, Kun [Key Laboratory of Cryogenics, Technical Institute of Physics and Chemistry, Chinese Academy of Sciences, P. O. Box 2711, Beijing 100190 (China); Graduate School of the Chinese Academy of Sciences, Beijing 100039 (China); Li, Qing; Zhou, Gang; Li, Qiang [Key Laboratory of Cryogenics, Technical Institute of Physics and Chemistry, Chinese Academy of Sciences, P. O. Box 2711, Beijing 100190 (China)

    2011-01-15

    Energy separation performance of vortex tube can be improved by using a divergent hot tube. Experiments are carried out to investigate the influence of the geometrical parameters on vortex tube refrigeration capacity by using nitrogen as the working fluid. In this work, the parameters are focused on the divergence angle of hot tube, length of divergent hot tube and number of nozzle intakes. Experimental results present that there is an optimum angle for obtaining the highest refrigeration performance, and 4 is the optimal candidate under our experimental conditions. Divergent tube length which exceeds a critical length has slight effect on the refrigeration capacity. The critical length to diameter ratio is L/D = 12 in our experiment. Increasing number of nozzle intakes increases the sensitivity of temperature reduction and can obtain the highest possible temperature reduction. Moreover, similarity relations for the prediction of the cold exit stream are presented and confirmed by the experimental data. (author)

  1. A $55 Shock Tube for Simulated Blast Waves

    OpenAIRE

    Courtney, Elijah; Courtney, Amy; Courtney, Michael

    2015-01-01

    Shock tubes are commonly employed to test candidate armor materials, validate numerical models, and conduct simulated blast experiments in animal models. As DoD interests desire to field wearable sensors as blast dosimeters, shock tubes may also serve for calibration and testing of these devices. The high blast pressures needed for experimental testing of candidate armors are unnecessary to test these sensors. An inexpensive, efficient, and easily available way of testing these pressure senso...

  2. Assessment methodology of power station boiler superheater based on risk-based inspection technology%基于风险检验技术的电站锅炉过热器评定方法

    Institute of Scientific and Technical Information of China (English)

    刘富君; 孔帅; 凌张伟; 郑慕林; 钱岳强; 金南辉; 王强; 李翔

    2011-01-01

    The risk assessment methodology based on risk-based inspection (RBI) was analyzed in order to evaluate the risk situation of the power station boiler superheater to establish the reasonable management, and maintenance strategy and reduce the non-plan shutdowns. The failure mechanism of power station boiler was analyzed, and the creep damage factor computing technical module and high-temperature smoke erosion thinning technical module for power station boiler tubes were conducted. The failure probability correction factor was presented based on the remaining life, considering China's national condition, including the extended service and initial material defects etc. Moreover, the proper financial risk calculation method was established to assess the risk consequence, and the grade distinguish rule was established. The risk level was evaluated through the failure possibility and consequence quantitative analysis and calculation of a superheater, and the reasonable management and maintenance strategy was established.%为了科学评价电站锅炉过热器的风险状况,制定合理的管理和维护策略,减少非计划停炉,研究基于风险检验(RBI)技术的过热器风险评定方法.研究过热器炉管的失效机理,建立适用于过热器炉管的高温烟气冲蚀因子和高温蠕变因子计算方法;结合我国超期服役、炉管材料初始缺陷等情况,提出基于剩余寿命参量的失效可能性修正系数;进一步确定合理的经济损失法来计算炉管失效后果,建立失效后果等级划分准则.通过对某末级过热器炉管失效的可能性和失效后果进行定量分析和计算,评定了炉管风险等级,制定了合理的管理和维护策略.

  3. Tracheostomy tube - eating

    Science.gov (United States)

    ... this page: //medlineplus.gov/ency/patientinstructions/000464.htm Tracheostomy tube - eating To use the sharing features on ... when you swallow foods or liquids. Eating and Tracheostomy Tubes When you get your tracheostomy tube, or ...

  4. Dynamic instabilities in radiation-heated boiler tubes for solar central receivers

    Science.gov (United States)

    Wolf, S.; Chan, K. C.; Chen, K.; Yadigaroglu, G.

    1982-11-01

    Density-wave instabilities have been investigated in circumferentially nonuniform radiation-heated boiler tubes, simulating solar heating. Analysis and experimental data are presented. The analysis provides the basis for a computer code, STEAMFREQ-I, for the prediction of density-wave instabilities in boiler tubes with imposed heat flux. The key model features include a drift-flux flow model in the boiling region, spatial variation of heat flux, wall dynamics, and variable steam properties in the superheat region. The experimental data include results from two radiation heated boiler panel tests. The data are applicable to central receivers for solar electric power plants. Data for stable and unstable conditions are compared with predictions from STEAMFREQ-I.

  5. Mechanistic modeling of pool film-boiling and quench on a Candu calandria tube following a critical break LOCA

    International Nuclear Information System (INIS)

    Following a postulated critical LBLOCA a pressure tube (PT) can experience creep deformation and balloon uniformly into contact with the calandria tube (CT). The resultant heat flux to CT is high as stored heat is transferred out of the hot PT. This heat flux can cause dryout on the outer surface of the CT and establish film boiling. This paper presents a model of buoyancy-driven natural convection film boiling on the outside of a horizontal tube with diameter relevant to a Candu CT (approximately 13 cm). A second order, non-linear and non-homogeneous ODE for vapour film thickness has been derived. The variation of steady state vapour film thickness prior to quench as a function of subcooling temperature, wall superheat, and incident heat flux is examined. The CT outer surface heatup rate and effective film boiling heat transfer coefficient from the model are in good agreement with available experimental data. (authors)

  6. Titanium condenser tubes

    International Nuclear Information System (INIS)

    The corrosion resistance of titanium in sea water is extremely excellent, but titanium tubes are expensive, and the copper alloy tubes resistant in polluted sea water were developed, therefore they were not used practically. In 1970, ammonia attack was found on the copper alloy tubes in the air-cooled portion of condensers, and titanium tubes have been used as the countermeasure. As the result of the use, the galvanic attack an copper alloy tube plates with titanium tubes as cathode and the hydrogen absorption at titanium tube ends owing to excess electrolytic protection were observed, but the corrosion resistance of titanium tubes was perfect. These problems can be controlled by the application of proper electrolytic protection. The condensers with all titanium tubes adopted recently in USA are intended to realize perfectly no-leak condensers as the countermeasure to the corrosion in steam generators of PWR plants. Regarding large condensers of nowadays, three problems are pointed out, namely the vibration of condenser tubes, the method of joining tubes and tube plates, and the tubes of no coolant leak. These three problems in case of titanium tubes were studied, and the problem of the fouling of tubes was also examined. The intervals of supporting plates for titanium tubes should be narrowed. The joining of titanium tubes and titanium tube plates by welding is feasible and promising. The cleaning with sponge balls is effective to control fouling. (Kako, I.)

  7. Failure problems in superheater spacers of steam generators; Problematica de fallas en espaciadores de sobrecalentadores de generadores de vapor

    Energy Technology Data Exchange (ETDEWEB)

    Chacon Nava, Jose G.; Martinez Villafane, Alberto [Instituto de Investigaciones Electricas, Cuernavaca (Mexico); Fuentes Samaniego, Raul [Universidad Autonoma de Nuevo Leon (Mexico); Mojica Calderon, Cecilio [Instituto de Investigaciones Electricas, Cuernavaca (Mexico)

    1988-12-31

    In this article the general aspects of the steam generator superheater fixed spacers failures are analyzed, emphasis is made on the influence several aspects such as the operation of the unit have, the appropriate execution of welds and the selection of binding materials. Likewise several recommendations are made to bring the failures to a minimum. [Espanol] En este articulo se analizan aspectos generales de fallas en espaciadores fijos de sobrecalentadores de generadores de vapor, y se hace hincapie en la influencia que tienen diversos aspectos tales como la operacion de la unidad, la adecuada ejecucion de soldaduras y la seleccion del material de aporte. Asimismo, se proponen algunas recomendaciones para reducir al minimo las fallas.

  8. Microstructure and tensile properties of friction welded SUS 304HCu austenitic stainless steel tubes

    International Nuclear Information System (INIS)

    Austenitic stainless steels are used in superheater/reheater tubing for their oxidation resistance and fireside corrosion resistance, in addition to their creep strength. The addition of 3 wt. % Cu to SUS 304HCu austenitic stainless steel to reduce the corrosion, has found to increase the creep performance in temperature range of 650°–750 °C. The addition of Cu to steels can have adverse effects on the mechanical properties of the fusion welded joints. During fusion welding, Cu can form low temperature eutectic phases that preferentially segregate to the grain boundaries and embrittle the alloy. There is a need for a better welding procedure/technique to fabricate this alloy. Friction welding is a solid state welding process which nullifies the adverse effects of low temperature eutectics segregation. Hence, in this investigation an attempt has been made to study the microstructural and tensile properties of the friction welded SUS 304HCu austenitic stainless steel tube joints fabricated using optimized parameters. -- Highlights: • Friction welding of SUS 304HCu tubes is reported. • Microstructures of friction welded SUS 304HCu tubes were reported. • Fracture surface of the tensile samples is characterized using SEM. • XRD analysis of the SUS 304HCu tube is reported

  9. 锅炉高温过热器管爆裂失效分析%Failure Analysis on High Temperature Superheater Tube Crack of Power Plant Boiler

    Institute of Scientific and Technical Information of China (English)

    王大江; 朱健

    2014-01-01

    对电厂锅炉高温过热器管爆裂样管进行宏观形貌分析、化学成分分析、金相组织检验及力学性能检测.结果表明,钢的化学成分符合标准要求,室温力学性能强度满足标准要求而塑性低于标准要求;珠光体出现球化,在晶界处有聚集碳化物颗粒析出,晶界已形成微裂纹,爆口附近出现蠕变孔洞;烟气腐蚀冲刷减薄管壁,造成高温过热器管在弯头外侧的开裂.建议加强对高温过热器管金属工作温度的监测,同时采取合理的防磨措施,以减少烟气对高温过热器管外壁的腐蚀冲刷.

  10. 电站锅炉过热器管失效规律研究%Failure Regularity of Superheater Tube in Power Plant Boiler

    Institute of Scientific and Technical Information of China (English)

    黄鑫; 丁克勤; 赵军

    2012-01-01

    过热器管是锅炉受热面中工作环境最恶劣的炉管,频繁地出现由材料断裂造成的泄漏与爆管失效事故,对电力企业造成了严重的经济损失.根据过热器管不同的失效原因,将过热器管的断裂失效分为韧性断裂、脆性断裂、蠕变断裂及腐蚀断裂.通过对过热器管失效实际案例进行分析,建立了过热器管失效树,同时概括了引起失效的损伤因素.为避免在生产过程中出现引起过热器管失效的重要损伤因素,在设计、运行、维护等环节提出了相应的防范措施.

  11. 重催CO过热器炉管失效分析%FAILURE ANALYSIS OF SUPERHEATER TUBES IN CATALYTIC REFORMING CARBON MONOOXIDE

    Institute of Scientific and Technical Information of China (English)

    刘钧泉; 熊文英; 夏延燊

    2006-01-01

    材质为12Cr1MoV的重催CO高温加热炉管,在服役25000h后发生胀管破裂.采用电镜、X射线、金相等测试技术对失效的原因进行分析后,判断本起失效的原因为长时间低幅度超温运行导致的蠕变开裂.

  12. 锅炉末级过热器换管后失效诊断%Failure Diagnosis after Changing Tube for Last Stage Superheater of Boiler

    Institute of Scientific and Technical Information of China (English)

    刘建国

    2005-01-01

    将一台1 021 t/h锅炉末级过热器材质存在问题的管段更换后,在启动试运行期间(即未报竣工)发生爆管,为了分析爆漏失效原因,对系统相关部位进行全面检查诊断,结合爆管特征分析认为:管子失效原因主要是施工工艺不良、管内杂物堵塞以致短期超温爆漏,特提出了处理和防范建议.

  13. 垃圾焚烧锅炉过热器管腐蚀失效分析%Analysis about the Failure of Boiler Superheater Tube

    Institute of Scientific and Technical Information of China (English)

    黄卫冲

    2014-01-01

    采用化学分析、宏观、微观检验等方法,对锅炉过热器管腐蚀造成原因进行分析.结果表明,燃烧垃圾中所产生的大量Cl、S等腐蚀性元素是该过热器管快速腐蚀的主要原因.

  14. Analysis of Convection Superheater Tube Rupture of Boiler%锅炉对流过热器爆管原因分析

    Institute of Scientific and Technical Information of China (English)

    刘丽梅; 杜双明; 蔡文河

    2012-01-01

    通过现场观察过热器管子爆口特征及管壁吹损痕迹,分析确认过热器受热面泄漏后管子相互损坏关系及首爆口.经对管子取样试验数据分析,首爆口处管壁存在以AI元素为主要成分的异种金属物质,影响了管子的使用性能,长期运行后导致管子发生爆破.同时,管子存在一定程度的过热现象,加速了管材性能的劣化.

  15. Neural Tube Defects

    Science.gov (United States)

    Neural tube defects are birth defects of the brain, spine, or spinal cord. They happen in the first month ... that she is pregnant. The two most common neural tube defects are spina bifida and anencephaly. In spina bifida, ...

  16. Tracheostomy tube - speaking

    Science.gov (United States)

    ... this page: //medlineplus.gov/ency/patientinstructions/000465.htm Tracheostomy tube - speaking To use the sharing features on ... are even speaking devices that can help you. Tracheostomy Tubes and Speaking Air passing through vocal cords ( ...

  17. Gastrostomy feeding tube - bolus

    Science.gov (United States)

    ... a gastrostomy tube. Delmar’s Fundamental and Advanced Nursing Skills . 2nd Ed. Albany, NY: Delmar Thomson Learning; 2003: 742-749. Simmons, Remmington R.The percutaneous endoscopic gastrostomy tube: a nurse's guide to PEG tubes. Medsurg Nurs . 2013 Mar- ...

  18. KER-2 tube history

    Energy Technology Data Exchange (ETDEWEB)

    Banister, W.C.

    1963-08-16

    Zirconium process tube No. 1986 was installed in KE Reactor tube channel No. 2864 on April 16, 1959. This report describes the history and the conditions to which it was exposed during its residence in the reactor. The tube was removed on May 31, 1963.

  19. 21 CFR 868.5800 - Tracheostomy tube and tube cuff.

    Science.gov (United States)

    2010-04-01

    ... 21 Food and Drugs 8 2010-04-01 2010-04-01 false Tracheostomy tube and tube cuff. 868.5800 Section... (CONTINUED) MEDICAL DEVICES ANESTHESIOLOGY DEVICES Therapeutic Devices § 868.5800 Tracheostomy tube and tube cuff. (a) Identification. A tracheostomy tube and tube cuff is a device intended to be placed into...

  20. Heat exchanger tube tool

    International Nuclear Information System (INIS)

    Certain types of heat-exchangers have tubes opening through a tube sheet to a manifold having an access opening offset from alignment with the tube ends. A tool for inserting a device, such as for inspection or repair, is provided for use in such instances. The tool is formed by a flexible guide tube insertable through the access opening and having an inner end provided with a connector for connection with the opening of the tube in which the device is to be inserted, and an outer end which remains outside of the chamber, the guide tube having adequate length for this arrangement. A flexible transport hose for internally transporting the device slides inside of the guide tube. This hose is long enough to slide through the guide tube, into the heat-exchanger tube, and through the latter to the extent required for the use of the device. The guide tube must be bent to reach the end of the heat-exchanger tube and the latter may be constructed with a bend, the hose carrying anit-friction elements at interspaced locations along its length to make it possible for the hose to negotiate such bends while sliding to the location where the use of the device is required

  1. NEI You Tube Videos: Amblyopia

    Medline Plus

    Full Text Available ... NEI YouTube Videos > NEI YouTube Videos: Amblyopia NEI YouTube Videos YouTube Videos Home Age-Related Macular Degeneration ... Retinopathy of Prematurity Science Spanish Videos Webinars NEI YouTube Videos: Amblyopia NEI on Twitter NEI on YouTube ...

  2. NEI You Tube Videos: Amblyopia

    Medline Plus

    Full Text Available ... YouTube Videos > NEI YouTube Videos: Amblyopia NEI YouTube Videos YouTube Videos Home Age-Related Macular Degeneration Amblyopia ... of Prematurity Science Spanish Videos Webinars NEI YouTube Videos: Amblyopia NEI on Twitter NEI on YouTube NEI ...

  3. Pediatric cuffed endotracheal tubes

    Directory of Open Access Journals (Sweden)

    Neerja Bhardwaj

    2013-01-01

    Full Text Available Endotracheal intubation in children is usually performed utilizing uncuffed endotracheal tubes for conduct of anesthesia as well as for prolonged ventilation in critical care units. However, uncuffed tubes may require multiple changes to avoid excessive air leak, with subsequent environmental pollution making the technique uneconomical. In addition, monitoring of ventilatory parameters, exhaled volumes, and end-expiratory gases may be unreliable. All these problems can be avoided by use of cuffed endotracheal tubes. Besides, cuffed endotracheal tubes may be of advantage in special situations like laparoscopic surgery and in surgical conditions at risk of aspiration. Magnetic resonance imaging (MRI scans in children have found the narrowest portion of larynx at rima glottides. Cuffed endotracheal tubes, therefore, will form a complete seal with low cuff pressure of <15 cm H 2 O without any increase in airway complications. Till recently, the use of cuffed endotracheal tubes was limited by variations in the tube design marketed by different manufacturers. The introduction of a new cuffed endotracheal tube in the market with improved tracheal sealing characteristics may encourage increased safe use of these tubes in clinical practice. A literature search using search words "cuffed endotracheal tube" and "children" from 1980 to January 2012 in PUBMED was conducted. Based on the search, the advantages and potential benefits of cuffed ETT are reviewed in this article.

  4. Dark matter candidates

    International Nuclear Information System (INIS)

    One of the simplest, yet most profound, questions we can ask about the Universe is, how much stuff is in it, and further what is that stuff composed of? Needless to say, the answer to this question has very important implications for the evolution of the Universe, determining both the ultimate fate and the course of structure formation. Remarkably, at this late date in the history of the Universe we still do not have a definitive answer to this simplest of questions---although we have some very intriguing clues. It is known with certainty that most of the material in the Universe is dark, and we have the strong suspicion that the dominant component of material in the Cosmos is not baryons, but rather is exotic relic elementary particles left over from the earliest, very hot epoch of the Universe. If true, the Dark Matter question is a most fundamental one facing both particle physics and cosmology. The leading particle dark matter candidates are: the axion, the neutralino, and a light neutrino species. All three candidates are accessible to experimental tests, and experiments are now in progress. In addition, there are several dark horse, long shot, candidates, including the superheavy magnetic monopole and soliton stars. 13 refs

  5. Conduction cooled tube supports

    Science.gov (United States)

    Worley, Arthur C.; Becht, IV, Charles

    1984-01-01

    In boilers, process tubes are suspended by means of support studs that are in thermal contact with and attached to the metal roof casing of the boiler and the upper bend portions of the process tubes. The support studs are sufficiently short that when the boiler is in use, the support studs are cooled by conduction of heat to the process tubes and the roof casing thereby maintaining the temperature of the stud so that it does not exceed 1400.degree. F.

  6. Tubing weld cracking test

    International Nuclear Information System (INIS)

    A tubing weld cracking (TWC) test was developed for applications involving advanced austenitic alloys (such as modified 800H and 310HCbN). Compared to the Finger hot cracking test, the TWC test shows an enhanced ability to evaluate the crack sensitivity of tubing materials. The TWC test can evaluate the cracking tendency of base as well as filter materials. Thus, it is a useful tool for tubing suppliers, filler metal producers and fabricators

  7. 硫磺尾气焚烧炉蒸汽过热器失效分析%Failure Analysis of Steam Superheater in Sulphur Tail Gas Incinerator

    Institute of Scientific and Technical Information of China (English)

    姜伟

    2012-01-01

    针对硫磺尾气焚烧炉蒸汽过热器的泄漏问题,结合其实际运行情况,从宏观和微观两方面分析了失效原因,提出了处理措施,取得了较好的效果.%The leakage cause of sulphur tail gas incinerator steam superheater was analyzed through macro and micro-examinations. And measures were taken on the basis of the failure analysis. Result showed that the measures had good effect.

  8. Environmental Assessment for Authorizing the Puerto Rico Electric Power Authority (PREPA) to allow Public Access to the Boiling Nuclear Superheat (BONUS) Reactor Building, Rincon, Puerto Rico

    International Nuclear Information System (INIS)

    The U.S. Department of Energy (DOE) proposes to consent to a proposal by the Puerto Rico Electric Power Authority (PREPA) to allow public access to the Boiling Nuclear Superheat (BONUS) reactor building located near Rincon, Puerto Rico for use as a museum. PREPA, the owner of the BONUS facility, has determined that the historical significance of this facility, as one of only two reactors of this design ever constructed in the world, warrants preservation in a museum, and that this museum would provide economic benefits to the local community through increased tourism. Therefore, PREPA is proposing development of the BONUS facility as a museum

  9. Categorising YouTube

    OpenAIRE

    Thomas Mosebo Simonsen

    2011-01-01

    This article provides a genre analytical approach to creating a typology of the User Generated Content (UGC) of YouTube. The article investigates the construction of navigation processes on the YouTube website. It suggests a pragmatic genre approach that is expanded through a focus on YouTube’s technological affordances. Through an analysis of the different pragmatic contexts of YouTube, it is argued that a taxonomic understanding of YouTube must be analysed in regards to the vacillation of a...

  10. Calibrations of photomultiplier tubes

    International Nuclear Information System (INIS)

    The experimental methods for calibration photomultiplier tubes used in the multichannel fast-pulse-detection system of Thomson scattering measurements for nuclear fusion devices is reported. The most important parameters of the photomultiplier tubes to be calibrated include: linearity of output electric signals to input light signals, response time of pulsed light, spectral response, absolute responsibility, and sensitivity as a function of the chain voltage. The calibrations of all these parameters are carried out by using EMI 9558 B and RCA 7265 photomultiplier tubes respectively. The experimental methods presented in the paper are common to those quantitative measurements that require phomultiplier tubes as detectors

  11. Composite Pulse Tube

    Science.gov (United States)

    Martin, Jerry L.; Cloyd, Jason H.

    2007-01-01

    A modification of the design of the pulse tube in a pulse-tube cryocooler reduces axial thermal conductance while preserving radial thermal conductance. It is desirable to minimize axial thermal conductance in the pulse-tube wall to minimize leakage of heat between the warm and cold ends of the pulse tube. At the same time, it is desirable to maximize radial thermal conductance at the cold end of the pulse tube to ensure adequate thermal contact between (1) a heat exchanger in the form of a stack of copper screens inside the pulse tube at the cold end and (2) the remainder of the cold tip, which is the object to which the heat load is applied and from which heat must be removed. The modified design yields a low-heat-leak pulse tube that can be easily integrated with a cold tip. A typical pulse tube of prior design is either a thin-walled metal tube or a metal tube with a nonmetallic lining. It is desirable that the outer surface of a pulse tube be cylindrical (in contradistinction to tapered) to simplify the design of a regenerator that is also part of the cryocooler. Under some conditions, it is desirable to taper the inner surface of the pulse tube to reduce acoustic streaming. The combination of a cylindrical outer surface and a tapered inner surface can lead to unacceptably large axial conduction if the pulse tube is made entirely of metal. Making the pulse-tube wall of a nonmetallic, lowthermal- conductivity material would not solve the problem because the wall would not afford the needed thermal contact for the stack of screens in the cold end. The modified design calls for fabricating the pulse tube in two parts: a longer, nonmetallic part that is tapered on the inside and cylindrical on the outside and a shorter, metallic part that is cylindrical on both the inside and the outside. The nonmetallic part can be made from G-10 fiberglass-reinforced epoxy or other low-thermal-conductivity, cryogenically compatible material. The metallic part must have high

  12. Manual tube welding torch

    International Nuclear Information System (INIS)

    In a welding torch which fits over a tube intermediate the ends thereof for welding the juncture between the tube and a boss on the back side of a tube plate, a split housing encloses a tungsten electrode, a filler wire duct and a fiber optic bundle arranged to observe the welding process. A shielding gas duct is provided in the housing. A screw is provided for setting electrode/work distance. Difficult remote tube welding operations can be performed with the apparatus. (author)

  13. Steam generator tube performance

    International Nuclear Information System (INIS)

    A survey of steam generator operating experience for 1986 has been carried out for 184 pressurized water and pressurized heavy-water reactors, and 1 water-cooled, graphite-moderated reactor. Tubes were plugged at 75 of the reactors (40.5%). In 1986, 3737 tubes were plugged (0.14% of those in service) and 3148 tubes were repaired by sleeving. A small number of reactors accounted for the bulk of the plugged tubes, a phenomenon consistent with previous years. For 1986, the available tubesheet sludge data for 38 reactors has been compiled into tabular form, and sludge/deposit data will be incorporated into all future surveys

  14. Particle Dark Matter Candidates

    CERN Document Server

    Scopel, Stefano

    2007-01-01

    I give a short overview on some of the favorite particle Cold Dark Matter candidates today, focusing on those having detectable interactions: the axion, the KK-photon in Universal Extra Dimensions, the heavy photon in Little Higgs and the neutralino in Supersymmetry. The neutralino is still the most popular, and today is available in different flavours: SUGRA, nuSUGRA, sub-GUT, Mirage mediation, NMSSM, effective MSSM, scenarios with CP violation. Some of these scenarios are already at the level of present sensitivities for direct DM searches.

  15. Steam generator tube failures

    Energy Technology Data Exchange (ETDEWEB)

    MacDonald, P.E.; Shah, V.N.; Ward, L.W.; Ellison, P.G.

    1996-04-01

    A review and summary of the available information on steam generator tubing failures and the impact of these failures on plant safety is presented. The following topics are covered: pressurized water reactor (PWR), Canadian deuterium uranium (CANDU) reactor, and Russian water moderated, water cooled energy reactor (VVER) steam generator degradation, PWR steam generator tube ruptures, the thermal-hydraulic response of a PWR plant with a faulted steam generator, the risk significance of steam generator tube rupture accidents, tubing inspection requirements and fitness-for-service criteria in various countries, and defect detection reliability and sizing accuracy. A significant number of steam generator tubes are defective and are removed from service or repaired each year. This wide spread damage has been caused by many diverse degradation mechanisms, some of which are difficult to detect and predict. In addition, spontaneous tube ruptures have occurred at the rate of about one every 2 years over the last 20 years, and incipient tube ruptures (tube failures usually identified with leak detection monitors just before rupture) have been occurring at the rate of about one per year. These ruptures have caused complex plant transients which have not always been easy for the reactor operators to control. Our analysis shows that if more than 15 tubes rupture during a main steam line break, the system response could lead to core melting. Although spontaneous and induced steam generator tube ruptures are small contributors to the total core damage frequency calculated in probabilistic risk assessments, they are risk significant because the radionuclides are likely to bypass the reactor containment building. The frequency of steam generator tube ruptures can be significantly reduced through appropriate and timely inspections and repairs or removal from service.

  16. Steam generator tube failures

    International Nuclear Information System (INIS)

    A review and summary of the available information on steam generator tubing failures and the impact of these failures on plant safety is presented. The following topics are covered: pressurized water reactor (PWR), Canadian deuterium uranium (CANDU) reactor, and Russian water moderated, water cooled energy reactor (VVER) steam generator degradation, PWR steam generator tube ruptures, the thermal-hydraulic response of a PWR plant with a faulted steam generator, the risk significance of steam generator tube rupture accidents, tubing inspection requirements and fitness-for-service criteria in various countries, and defect detection reliability and sizing accuracy. A significant number of steam generator tubes are defective and are removed from service or repaired each year. This wide spread damage has been caused by many diverse degradation mechanisms, some of which are difficult to detect and predict. In addition, spontaneous tube ruptures have occurred at the rate of about one every 2 years over the last 20 years, and incipient tube ruptures (tube failures usually identified with leak detection monitors just before rupture) have been occurring at the rate of about one per year. These ruptures have caused complex plant transients which have not always been easy for the reactor operators to control. Our analysis shows that if more than 15 tubes rupture during a main steam line break, the system response could lead to core melting. Although spontaneous and induced steam generator tube ruptures are small contributors to the total core damage frequency calculated in probabilistic risk assessments, they are risk significant because the radionuclides are likely to bypass the reactor containment building. The frequency of steam generator tube ruptures can be significantly reduced through appropriate and timely inspections and repairs or removal from service

  17. Heat transfer characteristics evaluation of heat exchangers of mock-up test facility with full-scale reaction tube for HTTR hydrogen production system (Contract research)

    International Nuclear Information System (INIS)

    Connection of hydrogen production system by steam reforming of methane to the High Temperature Engineering Test Reactor (HTTR) of the Japan Atomic Energy Research Institute (JAERI) has been surveyed until now. Mock-up test facility of this steam reforming system with full-scale reaction tube was constructed in FY 2001 and hydrogen of 120 Nm3/h was successfully produced in overall performance test. Totally 7 times operational tests were performed from March 2002 to December 2004. A lot of operational test data on heat exchanges were obtained in these tests. In this report specifications and structures of steam reformer, steam superheater, steam generator, condenser, helium gas cooler, feed gas heater and feed gas superheater were described. Heat transfer correlation equations for inside and outside tube were chosen from references. Spreadsheet programs were newly made to evaluate heat transfer characteristics from measured test data such as inlet and outlet temperature pressure and flow-rate. Overall heat-transfer coefficients obtained from the experimental data were compared and evaluated with the calculated values with heat transfer correlation equation. As a result, actual measurement values of all heat exchangers gave close agreement with the calculated values with correlation equations. Thermal efficiencies of the heat exchangers were adequate as they were well accorded with design value. (author)

  18. Pyrotechnic Tubing Connector

    Science.gov (United States)

    Graves, Thomas J.; Yang, Robert A.

    1988-01-01

    Tool forms mechanical seal at joint without levers or hydraulic apparatus. Proposed tool intended for use in outer space used on Earth by heavily garbed workers to join tubing in difficult environments. Called Pyrotool, used with Lokring (or equivalent) fittings. Piston slides in cylinder when pushed by gas from detonating pyrotechnic charge. Impulse of piston compresses fittings, sealing around butting ends of tubes.

  19. Welding Tubes In Place

    Science.gov (United States)

    Meredith, R.

    1984-01-01

    Special welding equipment joins metal tubes that carry pressurized cyrogenic fluids. Equipment small enough to be used in confined spaces in which such tubes often mounted. Welded joints lighter in weight and more leak-proof than joints made with mechanical fittings.

  20. Categorising YouTube

    DEFF Research Database (Denmark)

    Simonsen, Thomas Mosebo

    2011-01-01

    This article provides a genre analytical approach to creating a typology of the User Generated Content (UGC) of YouTube. The article investigates the construction of navigation processes on the YouTube website. It suggests a pragmatic genre approach that is expanded through a focus on YouTube’s...... technological affordances. Through an analysis of the different pragmatic contexts of YouTube, it is argued that a taxonomic understanding of YouTube must be analysed in regards to the vacillation of a user-driven bottom-up folksonomy and a hierarchical browsing system that emphasises a culture of competition...... and which favours the already popular content of YouTube. With this taxonomic approach, the UGC videos are registered and analysed in terms of empirically based observations. The article identifies various UGC categories and their principal characteristics. Furthermore, general tendencies of the UGC...

  1. Estimation of residual life of boiler tubes using steamside oxide scale thickness

    International Nuclear Information System (INIS)

    In thermal power plants, remaining-life-estimation of boiler tubes is required at regular intervals for a safer and a better functionality of boilers. In this paper, a new method is proposed for the residual life estimation of service exposed boiler tubes using Non-Destructive Ultrasonic Oxide scale thickness measurements, average metal temperature and creep master curve. While steady state conduction heat transfer equations are solved to calculate the average metal temperature, creep master curve is generated from short term stress rupture data of rupture life less than 5000 h on a virgin material. In the present study, the residual life of T22 (2.25Cr-1Mo) service exposed Platen Superheater tube is estimated using two master creep curves, i.e. Larson-Miller Parametric (LMP) method of standard ASME T22 creep data and Wilshire approach of short term stress rupture data of T22. As the residual life is calculated from fundamental conduction heat transfer theory and creep rupture data, the proposed method can be applied for different grades of boiler materials. -- Highlights: ► Residual life is calculated from non-destructive oxide scale thickness, creep master curve and average metal temperature. ► A new method is proposed for calculating residual life using above parameters and from conduction heat transfer principles. ► The method can be applied to different boiler grades for estimating residual life and hence the method is generic

  2. High temperature corrosion during waste incineration : characterisation, causes and prevention of chlorine-induced corrosion

    OpenAIRE

    Viklund, Peter

    2011-01-01

    Waste-fired boilers suffer severely from corrosion of critical components such as superheater tubes. In this work the high temperature corrosion of candidate superheater alloys have been investigated by detailed laboratory studies and controlled field exposures in full-scale boilers. In a laboratory study the detrimental effect of gaseous hydrochloric acid (HCl) on three  different ground surface and preoxidised austenitic stainless steels was investigated. Exposures were conducted in an envi...

  3. Pressure tube type reactor

    International Nuclear Information System (INIS)

    Heretofore, a pressure tube type reactor has a problem in that the evaluation for the reactor core performance is complicate and no sufficient consideration is made for the economical property, to increase the size of a calandria tank and make the cost expensive. Then, in the present invention, the inner diameter of a pressure tube is set to greater than 50% of the lattice gap in a square lattice like arrangement, and the difference between the inner and the outer diameters of the calandria tube is set smaller than 20% of the lattice gap. Further, the inner diameter of the pressure tube is set to greater than 40% and the difference between the inner and the outer diameters of the calandria tube is set smaller than 30% of the lattice gap in a triangle lattice arrangement. Then, heavy water-to-fuel volume ratio can be determined appropriately and the value for the coolant void coefficient is made more negative side, to improve the self controllability inherent to the reactor. In particular, when 72 to 90 fuel rods are arranged per one pressure tube, the power density per one fuel rod is can be increased by about twice. Accordingly, the number of the pressure tubes can be reduced about to one-half, thereby enabling to remarkably decrease the diameter of the reactor core and to reduce the size of the calandria, which is economical. (N.H.)

  4. A search for intact lava tubes on the Moon: Possible lunar base habitats

    Science.gov (United States)

    Coombs, Cassandra R.; Hawke, B. Ray

    1992-01-01

    We have surveyed lunar sinuous rilles and other volcanic features in an effort to locate intact lava tubes that could be used to house an advanced lunar base. Criteria were established for identifying intact tube segments. Sixty-seven tube candidates within 20 rilles were identified on the lunar nearside. The rilles, located in four mare regions, varied in size and sinuosity. We identified four rilles that exhibited particularly strong evidence for the existence of intact lava tube segments. These are located in the following areas: (1) south of Gruithuisen K, (2) in the Marius Hills region, (3) in the southeastern Mare Serenitatis, and (4) in the eastern Mare Serenitatis. We rated each of the 67 probable tube segments for lunar base suitability based on its dimensions, stability, location, and access to lunar resources. Nine tube segments associated with three separate rilles are considered prime candidates for use as part of an advanced lunar base.

  5. A study on LMFBR steam generator design without tube failure propagation in water leak events

    International Nuclear Information System (INIS)

    The major target performance of the SG for commercialized FBR is not only economic performance but also property protection performance. The candidate SG design will be selected at the end of JFY 2010. The straight double wall tube SG is one of the SG candidates for commercialized FBR, and other SG concepts were studied in this paper. In proposing an alternative SG, alternative technological measures with a double wall tube were investigated and included reinforcing the tube against wastage and quick detection of initial tube leaks. Alternative SG concept candidates for preventing tube failure propagation and mitigation of water leak accidents were proposed through a combination of technological measures. The candidates were then comparatively evaluated from the point of view of property protection performance, total weight, technological issues, and so on. A coated wall tube SG and protective wall tube SG were decided on as the alternative SGs because of superior property protection performance and with the technological issues. At the end of JFY 2010, the straight double wall tube SG will be decided upon as the result of R and D activities, and alternative SGs evaluated in feasibility studies. A plan for studying feasibility with the technological issues of the alternative SG was proposed. (author)

  6. Magnetic flux tube tunneling

    International Nuclear Information System (INIS)

    We present numerical simulations of the collision and subsequent interaction of orthogonal magnetic flux tubes. The simulations were carried out using a parallelized spectral algorithm for compressible magnetohydrodynamics. It is found that, under a wide range of conditions, the flux tubes can open-quotes tunnelclose quotes through each other, a behavior not previously seen in studies of either vortex tube or magnetic flux tube interactions. Two conditions must be satisfied for tunneling to occur: the magnetic field must be highly twisted with a field line pitch >1, and the Lundquist number must be somewhat large, ≥2880. An examination of magnetic field lines suggests that tunneling is due to a double-reconnection mechanism. Initially orthogonal field lines reconnect at two specific locations, exchange interacting sections, and open-quotes passclose quotes through each other. The implications of these results for solar and space plasmas are discussed. copyright 1997 The American Physical Society

  7. Integrated structure vacuum tube

    Science.gov (United States)

    Dimeff, J.; Kerwin, W. J. (Inventor)

    1976-01-01

    High efficiency, multi-dimensional thin film vacuum tubes suitable for use in high temperature, high radiation environments are described. The tubes are fabricated by placing thin film electrode members in selected arrays on facing interior wall surfaces of an alumina substrate envelope. Cathode members are formed using thin films of triple carbonate. The photoresist used in photolithography aids in activation of the cathodes by carbonizing and reacting with the reduced carbonates when heated in vacuum during forming. The finely powdered triple carbonate is mixed with the photoresist used to delineate the cathode locations in the conventional solid state photolithographic manner. Anode and grid members are formed using thin films of refractory metal. Electron flow in the tubes is between grid elements from cathode to anode as in a conventional three-dimensional tube.

  8. Neural Tube Defects

    OpenAIRE

    Greene, Nicholas D. E.; Copp, Andrew J.

    2014-01-01

    Neural tube defects (NTDs), including spina bifida and anencephaly, are severe birth defects of the central nervous system that originate during embryonic development when the neural tube fails to close completely. Human NTDs are multifactorial, with contributions from both genetic and environmental factors. The genetic basis is not yet well understood, but several nongenetic risk factors have been identified as have possibilities for prevention by maternal folic acid supplementation. Mechani...

  9. Power vacuum tubes handbook

    CERN Document Server

    Whitaker, Jerry

    2012-01-01

    Providing examples of applications, Power Vacuum Tubes Handbook, Third Edition examines the underlying technology of each type of power vacuum tube device in common use today. The author presents basic principles, reports on new development efforts, and discusses implementation and maintenance considerations. Supporting mathematical equations and extensive technical illustrations and schematic diagrams help readers understand the material. Translate Principles into Specific Applications This one-stop reference is a hands-on guide for engineering personnel involved in the design, specification,

  10. Reduced order model of draft tube flow

    International Nuclear Information System (INIS)

    Swirling flow with compact coherent structures is very good candidate for proper orthogonal decomposition (POD), i.e. for decomposition into eigenmodes, which are the cornerstones of the flow field. Present paper focuses on POD of steady flows, which correspond to different operating points of Francis turbine draft tube flow. Set of eigenmodes is built using a limited number of snapshots from computational simulations. Resulting reduced order model (ROM) describes whole operating range of the draft tube. ROM enables to interpolate in between the operating points exploiting the knowledge about significance of particular eigenmodes and thus reconstruct the velocity field in any operating point within the given range. Practical example, which employs axisymmetric simulations of the draft tube flow, illustrates accuracy of ROM in regions without vortex breakdown together with need for higher resolution of the snapshot database close to location of sudden flow changes (e.g. vortex breakdown). ROM based on POD interpolation is very suitable tool for insight into flow physics of the draft tube flows (especially energy transfers in between different operating points), for supply of data for subsequent stability analysis or as an initialization database for advanced flow simulations

  11. The development and application of overheating failure model of FBR steam generator tubes. 3

    International Nuclear Information System (INIS)

    The model has been developed for the assessment of the overheating tube failure in an event of sodium-water reaction accident of fast breeder reactor's steam generators (SGs). The model has been applied to the Monju SG studies. Major results obtained in the studies are as follows: 1. To evaluate the structural integrity of tube material, the strength standard for 2. 25Cr-1Mo steel was established taking account of time dependent effect based on the high temperature (700-1200degC) creep data. This standard has been validated with the tube rupture simulation test data. 2. The conditions for overheating by the high temperature reaction were determined by use of the SWAT-3 experimental data. The realistic local heating conditions (reaction zone temperature and related heat transfer conditions) for the sodium-water reaction were proposed as the cosine-shaped temperature profile. 3. For the cooling effects inside of target tubes, LWR's studies of critical heat flux (CHF) and post-CHF heat transfer correlations have been examined and considered in the model. 4. The model has been validated with experimental data obtained by SWAT-3 and LLTR. The results were satisfactory with conservatism. The PFR superheater leak event in 1987 was studied, and the cause of event and the effectiveness of the improvement after the leak event could be identified by the analysis. 5. The model has been applied to the Monju SG studies. It is revealed consequently that no tube failure occurs in 100%, 40%, and 10% water flow operating conditions when an initial leak is detected by the cover gas pressure detection system. (author)

  12. Ultrasonic wall thickness gauging for ferritic steam generator tubing as an in-service inspection tool

    International Nuclear Information System (INIS)

    In-service inspection of LWR steam generators is more or less a standard routine operation. The situation can be very different for LMFBRs. For the SNR 300 (Kalkar Power Station) the situation is different because the steam generators have ferritic tubing. The tube walls are comparatively thick, 2 to 4.5 mm. During inservice examinations the steam generators will be drained on both sides, however on the sodium side a sodium film will be present. Furthermore the SNR 300 will have two types of steam generator. A straight tube design and a helical coil design will be used. Both types consist of a evaporator and superheater. The steam generators are of course not radioactive. It is obvious that in this case the eddy current (EC) technique is not an enviable inservice inspection tool. Basically EC is a surface flaw detection technique. Only the saturation magnetisation method will improve the EC technique sufficiently for ferritic material. However the 'in bore examination' with the saturation technique was, in case of the SNR 300 steam generator tubing, considered impossible since the inner diameters are fairly small. Furthermore sodium traces may influence the EC method. Although multifrequency methods can solve this problem, EC is not considered as a useful tool for examining ferritic tubing. Another method is to employ the 'stray flux' method which is under development with the TNO organization in Holland. The EC and stray flux method do have one drawback, these methods do not detect gradual changes in wall thickness. Ultrasonic examinations will be used in the SNR 300 as the main inspection tool for the steam generators. In this paper the reasons why ultrasonic examination was selected are explained. The results of the development work on this subject are discussed

  13. Aeronautical tubes and pipes

    Science.gov (United States)

    Beauclair, N.

    1984-12-01

    The main and subcomponent French suppliers of aircraft tubes and pipes are discussed, and the state of the industry is analyzed. Quality control is essential for tubes with regard to their i.d. and metallurgical compositions. French regulations do not allow welded seam tubes in hydraulic circuits unless no other form is available, and then rustproofed steel must be installed. The actual low level of orders for any run of tubes dictates that the product is only one of several among the manufacturers' line. Automation, both in NDT and quality control, assures that the tubes meet specifications. A total of 10 French companies participate in the industry, serving both civil and military needs, with some companies specializing only in titanium, steel, or aluminum materials. Concerns wishing to enter the market must upgrade their equipment to meet the higher aeronautical specifications and be prepared to furnish tubes and pipes that serve both functional and structural purposes simultaneously. Additionally, pipe-bending machines must also perform to tight specifications. Pipes can range from 0.2 mm exterior diameter to 40 mm, with wall thicknesses from 0.02 mm to 3 mm. A chart containing a list of manufacturers and their respective specifications and characteristics is presented, and a downtrend in production with reduction of personnel is noted.

  14. 造气联合过热器及洗气塔系统优化%Optimization of gasification combined superheater and scrubbing tower system

    Institute of Scientific and Technical Information of China (English)

    崔文科

    2014-01-01

    对造气系统工艺、设备等存在的问题进行了分析,采取了以联合过热器、洗气塔为主的系统优化改造,改造后系统阻力和煤耗明显降低,系统得以安全长周期运行。%The paper analyses existing problems, such as process and equipment, in the gasification system, by optimization and modification of gasification combined superheater and scrubbing tower system, systemic resistance and coal consumption decreases, the system runs in a long period of time safely.

  15. Geiger-Muller tubes

    International Nuclear Information System (INIS)

    A Geiger-Muller tube designed for use in an environment (for example, mounted on a rock drill) where subjected to mechanical shock and vibration has a tensioned anode wire secured by welding to securement members between first and second mounts at opposite ends of the tube envelope. The wire tension is adjusted to a high value with a screwable-adjustment means which is locked eg. by a spot-weld or by a locking nut, in the adjusted position, so that the natural frequency of the vibration of the tensioned wire does not resonate with (and may be much higher than) the frequencies to which the tube is subjected in use. The wire frequency is typically in excess of 400Hz and even 500Hz. The adjustment means may be included in the mount via which the envelope is evacuated and back-filled with the ionizible gas, and a gas-tight seal can be provided around this part of the mount, for example by sealing off the gas pump tube. However the adjustment means may be designed into another part of the tube, for example using telescopic parts of the envelope whose sliding junction is made gas tight with a flexible seal. (author)

  16. Categorising YouTube

    Directory of Open Access Journals (Sweden)

    Thomas Mosebo Simonsen

    2011-09-01

    Full Text Available This article provides a genre analytical approach to creating a typology of the User Generated Content (UGC of YouTube. The article investigates the construction of navigationprocesses on the YouTube website. It suggests a pragmatic genre approach that is expanded through a focus on YouTube’s technological affordances. Through an analysis of the different pragmatic contexts of YouTube, it is argued that a taxonomic understanding of YouTube must be analysed in regards to the vacillation of a user-driven bottom-up folksonomy and a hierarchical browsing system that emphasises a culture of competition and which favours the already popular content of YouTube. With this taxonomic approach, the UGC videos are registered and analysed in terms of empirically based observations. The article identifies various UGC categories and their principal characteristics. Furthermore, general tendencies of the UGC within the interacting relationship of new and old genres are discussed. It is argued that the utility of a conventional categorical system is primarily of analytical and theoretical interest rather than as a practical instrument.

  17. Electoral Systems and Candidate Selection

    NARCIS (Netherlands)

    Hazan, Reuven Y.; Voerman, Gerrit

    2006-01-01

    Electoral systems at the national level and candidate selection methods at the party level are connected, maybe not causally but they do influence each other. More precisely, the electoral system constrains and conditions the parties' menu of choices concerning candidate selection. Moreover, in ligh

  18. Damage Analyses of Reformer Tubes in SRT-IV-HS Furnace%SRT-IV-HS型裂解炉管损伤分析

    Institute of Scientific and Technical Information of China (English)

    李若平; 方鲁晋

    2001-01-01

    通过现场测试和实验室试验,研究了SRT-IV-HS炉管的损伤失效形式。结果表明:高温渗碳、热冲击开裂和蠕变是造成炉管失效的主要原因。当炉管长期在高温下工作时,介质中的碳会渗入到显微组织中,这不仅使材料脆化,而且使渗碳表面产生残余应力,导致炉管开裂。热冲击是由于炉管在某些部位温度变化大,炉管和结焦物的热膨胀系数不同,而产生较大的温差应力,使炉管产生裂纹。高温蠕变损伤是由于过热引起的,过热使金相组织内部产生蠕变空洞,在热应力下空洞扩展连接而形成蠕变裂纹。根据失效损伤分析,提出了防止炉管损伤并延长其使用寿命的6条措施。%By means of spot inspections and experiments in the laboratory,the damage types of tubes HP40Nb in SRT-IV-HS furnace has been researched. The resul ts show t hat carburizing, hot attack and creep at high temperature are main factors to ma ke the tubes usable. The carbon in the media w ill diffuse in microstructure, which not only embrittles the tubes, but also pro duces the residual stresses on their surface. For these reasons, the tubes crack . Because of large temperature differences in some local tubes and different expa nsion coefficients, large stresses of temperature difference are produced and br ings about cracking in tubes. Creep damage is mainly caused by superheat. Becaus e of superheat, creep cavities are formed inside microstructure, under heat stres s condition, growth and join of cavities induce creep cracking. Acoording to dam age analyses, six kinds of measures are proposed to provent tubes from fai lure and to elongate tube lifetime.

  19. Effect of tube size on electromagnetic tube bulging

    Institute of Scientific and Technical Information of China (English)

    2007-01-01

    The commercial finite code ANSYS was employed for the simulation of the electromagnetic tube bulging process. The finite element model and boundary conditions were thoroughly discussed. ANSYS/EMAG was used to model the time varying electromagnetic field in order to obtain the radial and axial magnetic pressure acting on the tube. The magnetic pressure was then used as boundary conditions to model the high velocity deformation of various length tube with ANSYS/LSDYNA. The time space distribution of magnetic pressure on various length tubes was presented. Effect of tube size on the distribution of radial magnetic pressure and axial magnetic pressure and high velocity deformation were discussed. According to the radial magnetic pressure ratio of tube end to tube center and corresponding dimensionless length ratio of tube to coil, the free electromagnetic tube bulging was studied in classification. The calculated results show good agreements with practice.

  20. Kajian Efektifitas Sistem Struktur Tube Dengan Sistem Struktur Tube In Tube Di Bawah Beban Gempa

    OpenAIRE

    Sihotang, Dian Frisca

    2010-01-01

    Berkembangnya teknologi telah melahirkan berbagai sistem struktur bangunan tahan gempa, seperti penggunaan sistem tube.Tube adalah merupakan frame penahan gaya yang menahan gaya gaya lateral dengan struktur kantilever kotak yang memiliki jarak kolom yang berdekatan yang dipasang pada sekeliling gedung, sehingga penampilan wajah depan gedung seperti lubang jendela jendela yang terbuka. Rancangan tube ini kemudian dimodifikasi lagi dengan menambah pengaku pada bagian dalam ( konsep tube in tube...

  1. Neural tube defects

    OpenAIRE

    M.E. Marshall

    1981-01-01

    Neural tube defects refer to any defect in the morphogenesis of the neural tube, the most common types being spina bifida and anencephaly. Spina bifida has been recognised in skeletons found in north-eastern Morocco and estimated to have an age of almost 12 000 years. It was also known to the ancient Greek and Arabian physicians who thought that the bony defect was due to the tumour. The term spina bifida was first used by Professor Nicolai Tulp of Amsterdam in 1652. Many other terms have bee...

  2. Fatigue crack analysis of EBR-II Ni-bonded duplex tubing

    Energy Technology Data Exchange (ETDEWEB)

    Jackson, J.H., E-mail: john.jackson@inl.gov [Material Properties and Performance, Idaho National Laboratory, P.O. Box 1625, Idaho Falls, ID 83415-2218 (United States); Porter, D.L.; Lloyd, W.R. [Material Properties and Performance, Idaho National Laboratory, P.O. Box 1625, Idaho Falls, ID 83415-2218 (United States); Kisohara, N. [Japan Atomic Energy Agency, 4002 Narita, O-arai, Higashi-Ibaraki, Ibaraki 311-1393 (Japan)

    2011-03-15

    Small, notched three-point bend specimens machined from duplex tubes, which were extracted from an EBR-II superheater, were fatigued through the nickel interlayer to determine propensity for crack arrest within this interlayer. Several of these specimens were fatigued in the near threshold, and steady state regimes of Paris Law behavior. Additionally, two specimens were fatigued to the edge of the nickel interlayer and then monotonically loaded. Micro-hardness profiles of the nickel interlayer were also measured. Fatigue behavior was found to be similar to previous studies in that arrest was only noted in the near threshold Paris regime (attributed to the presence of voids) and in the steady state regime exhibited an acceleration of crack growth rate through the nickel interlayer followed by a slight retardation. Monotonic loading resulted in crack branching or delamination along the interlayer. Although archival material was not available for this study, the hardness of the nickel interlayer was determined to have been lowered slightly during service by comparison to the expected hardness of a similar nickel braze prepared as specified for fabrication of these tubes.

  3. Failure analysis of bursting 12Cr2MoWVTiB steel pipe of platen superheater for 135 MW boiler%135 MW 锅炉屏式过热器12Cr2MoWVTiB钢爆管失效分析

    Institute of Scientific and Technical Information of China (English)

    朱海宝; 高国宏; 卓仁春; 奚杰峰

    2014-01-01

    采用化学成分分析、力学性能测试和组织分析等方法,对屏式过热器12Cr2MoWVTiB钢爆管进行了失效研究。结果表明,爆口处化学成分无明显异常,硬度比正常处低约25 HV0.1,显微组织出现明显软化。分析认为,管子长期在超温条件下服役,组织老化导致材料力学性能下降;由于屏过穿排定位管和外圈竖直管相互磨损发生泄漏,后段管子内介质流量减小,壁温迅速升高,短时过热在高温下组织快速软化,造成管子切向应力超过材料强度而发生瞬时超温爆管。%The failure of the platen superheater 12Cr2MoWVTiB steel bursting pipe from a power plant were studied by chemical composition analysis, mechanical properties test and microstructure analysis etc.The results show that chemical composition of the explosion position is normal, but the hardness is about 25 HV0.1 lower than the other area and microstructure is apparently softened.Analysis indicates that microstructure becomes outworn and mechanical properties drop due to long-time over-temperature condition; because of wear leakage between the row positioning tube and the outer vertical tube,the medium flow of the rear tube decreases, and temperature of the tube wall raises rapidly,so the microstructure is quickly softened at the high temperature causing the pipe'tangential stress exceeding the strength of the material itself which leading to pipe bursting in the condition of over-temperature instantaneously.

  4. Prawns in Bamboo Tube

    Institute of Scientific and Technical Information of China (English)

    1998-01-01

    Ingredients: 400 grams Jiwei prawns, 25 grams pork shreds, 5 grams sliced garlic. Condiments: 5 grams cooking oil, minced ginger root and scallions, cooking wine, salt, pepper and MSG (optional) Method: 1. Place the Shelled prawns into a bowl and mix with all the condiments. 2. Stuff the prawns into a fresh bamboo tube,

  5. Thoughts of accelerator tubes

    International Nuclear Information System (INIS)

    A brief, subjective review is given of mechanisms that may be limiting electrostatic accelerator tubes to present levels of performance. Suggestions are made for attacking these limitations with the purpose of stimulating the thinking of designers and users of electrostatic accelerators

  6. Development of 18Cr-9Ni-W-Nb-V-N Austenitic Stainless Steel Tube for Thermal Power Boilers

    Science.gov (United States)

    Ishitsuka, Tetsuo; Mimura, Hiroyuki

    An 18Cr-9Ni-W-Nb-V-N austenitic stainless steel tube for thermal power boilers has been newly developed. The high temperature mechanical properties and corrosion resistance of the steel were investigated. The creep rupture strength of the developed steel is about 1.5 times as high as that of SUS347HTB, and is almost the same as that of Ka-SUS310J2TB at 650°C. This excellent creep strength of the steel is mainly due to solid solution strengthening by tungsten and nitrogen, and precipitation strengthening by nitrides of niobium and vanadium. The carbon content of the steel is reduced to 0.03% to improve intergranular corrosion resistance. The steam oxidation resistance and the high temperature corrosion resistance of the tube are almost the same as those of SUS347HTB. Weldability of the developed steel is superior to that of SUS304HTB and SUS310TB. Thus the developed steel is suitable for use as a material for superheater and reheater tubes of thermal power boilers.

  7. Quarter-wave pulse tube

    Science.gov (United States)

    Swift, G. W.; Gardner, D. L.; Backhaus, S. N.

    2011-10-01

    In high-power pulse-tube refrigerators, the pulse tube itself can be very long without too much dissipation of acoustic power on its walls. The pressure amplitude, the volume-flow-rate amplitude, and the time phase between them evolve significantly along a pulse tube that is about a quarter-wavelength long. Proper choice of length and area makes the oscillations at the ambient end of the long pulse tube optimal for driving a second, smaller pulse-tube refrigerator, thereby utilizing the acoustic power that would typically have been dissipated in the first pulse-tube refrigerator's orifice. Experiments show that little heat is carried from the ambient heat exchanger to the cold heat exchanger in such a long pulse tube, even though the oscillations are turbulent and even when the tube is compactly coiled.

  8. Drift tubes of Linac 2

    CERN Multimedia

    Photographic Service

    1977-01-01

    Being redied for installation, those at the right are for tank 1, those on the left for tank 2. Contrary to Linac 1, which had drift-tubes supported on stems, here the tubes are suspended, for better mechanical stability.

  9. Laser welding of a tube

    International Nuclear Information System (INIS)

    For sleeving PWR steam generator tubes, the welding laser work is made under protection of a primary gas going out by the crossing window of the laser and under a secondary gas flowing axially through the head and the tube

  10. Tubing For Sampling Hydrazine Vapor

    Science.gov (United States)

    Travis, Josh; Taffe, Patricia S.; Rose-Pehrsson, Susan L.; Wyatt, Jeffrey R.

    1993-01-01

    Report evaluates flexible tubing used for transporting such hypergolic vapors as those of hydrazines for quantitative analysis. Describes experiments in which variety of tubing materials, chosen for their known compatibility with hydrazine, flexibility, and resistance to heat.

  11. Ultrasonic nondestructive tubing inspection system

    International Nuclear Information System (INIS)

    A system for measuring the extent of tube wall erosion in an inspection region of a heat exchanger tube of a nuclear steam generator, uses an ultrasonic means driven helically inside the eroded tube which may be filled with a fluid (e.g., water) to minimize ultrasonic wave attenuation. A control means cooperates with the ultrasonic means to produce a map of the tube wall thickness in an inspection region

  12. Sleeve puller salvages welded tubes

    Science.gov (United States)

    Weaver, J. F.

    1980-01-01

    Tool removes sleeve remnants without distorting or damaging tubes, unlike pliers and other conventional handtools. Tubes can be reused, saving time, labor, and material in many applications. Sleeve-removal fixture consists of pressure screw, swing arm, locking screws, and base. It removes sleeve remnant from tubing after welded joint has been sawed through.

  13. Neural tube defects

    Directory of Open Access Journals (Sweden)

    M.E. Marshall

    1981-09-01

    Full Text Available Neural tube defects refer to any defect in the morphogenesis of the neural tube, the most common types being spina bifida and anencephaly. Spina bifida has been recognised in skeletons found in north-eastern Morocco and estimated to have an age of almost 12 000 years. It was also known to the ancient Greek and Arabian physicians who thought that the bony defect was due to the tumour. The term spina bifida was first used by Professor Nicolai Tulp of Amsterdam in 1652. Many other terms have been used to describe this defect, but spina bifida remains the most useful general term, as it describes the separation of the vertebral elements in the midline.

  14. X-ray tubes

    International Nuclear Information System (INIS)

    An improved form of x-ray tube is described which consists of a rotatable anode disc and an electron beam source enclosed in an envelope. The beam of electrons strikes the edge of the anode disc at an acute angle, producing x-rays which are transmitted through a window in the envelope. To improve performance and life of the anode disc it is additionally reciprocated back and forth along its axis of rotation. Dimensions are specified. (U.K.)

  15. Primary fallopian tube carcinoma

    Directory of Open Access Journals (Sweden)

    Mladenović-Segedi Ljiljana

    2009-01-01

    Full Text Available Introduction. Primary fallopian tube carcinoma is extremely rare, making 0.3-1.6% of all female genital tract malignancies. Although the etymology of this tumor is unknown, it is suggested to be associated with chronic tubal inflammation, infertility, tuberculous salpingitis and tubal endometriosis. High parity is considered to be protective. Cytogenetic studies show the disease to be associated with over expression of p53, HER2/neu and c-myb. There is also some evidence that BRCA1 and BRCA2 mutations have a role in umorogeneis. Clinical features. The most prevailing symptoms with fallopian tube carcinoma are abdominal pain, abnormal vaginal discharge/bleeding and the most common finding is an adnexal mass. In many patients, fallopian tube carcinoma is asymptomatic. Diagnosis. Due to its rarity, preoperative diagnosis of primary fallopian tube carcinoma is rarely made. It is usually misdiagnosed as ovarian carcinoma, tuboovarian abscess or ectopic pregnancy. Sonographic features of the tumor are non-specific and include the presence of a fluid-filled adnexal structure with a significant solid component, a sausage-shaped mass, a cystic mass with papillary projections within, a cystic mass with cog wheel appearance and an ovoid-shaped structure containing an incomplete separation and a highly vascular solid nodule. More than 80% of patients have elevated pretreatment serum CA-125 levels, which is useful in follow-up after the definite treatment. Treatment. The treatment approach is similar to that of ovarian carcinoma, and includes total abdominal hysterectomy and bilateral salpingo-oophorectomy. Staging is followed with chemotherapy.

  16. Fabrication of seamless calandria tubes

    International Nuclear Information System (INIS)

    Full text: Calandria tube is a large diameter, thin walled zircaloy-4 tube and is an important structural component of PHWR type of reactors. These tubes are lifetime components and remain during the full life of the reactor. Calandria tubes are classified as extremely thin walled tubes with a diameter to wall thickness ratio of around 96. Such thin walled tubes are conventionally produced by seam welded route comprising of extrusion of slabs followed by a series of hot and rolling passes, shaping into O-shape and eventual welding. An alternative and superior method of fabricating the calandria tubes, the seamless route, has been developed, which involves hot extrusion of mother blanks followed by three successive cold pilger reductions. Eccentricity correction of the extruded blanks is carried out on a special purpose grinding equipment to bring the wall thickness variation within permissible limits. Predominant wall thickness reductions are given during cold pilgering to ensure high Q-factor values. The texture in the finished tubes could be closely, controlled with an average fr value of 0.65. Pilgering parameters and tube guiding system have been specially designed to facilities rolling of thin walled tubes. Seamless calandria tubes have distinct advantages over welded tubes. In addition to the absence of weld, they are dimensionally more stable, lighter in weight and possess uniform grains with superior grain size. The cycle time from billet to finished product is substantially reduced and the product is amenable to high level of quality assurance. The most significant feature of the seamless route is its material recovery over welded route. Residual stresses measured in the tubes indicate that these are negligible and uniform along the length of the tube. In view of their superior quality, the first charge of seamless calandria tubes will be rolled into the first 500 MWe Pressurised Heavy Water Reactor at Tarapur

  17. Clogging of feeding tubes.

    Science.gov (United States)

    Marcuard, S P; Perkins, A M

    1988-01-01

    This is a report of an in vitro study evaluating clotting ability of some formulas with intact protein and hydrolyzed protein sources in a series of buffers ranging from a pH of 1 thru 10. The following 10 products were tested: Ensure Plus, Ensure, Enrich, Osmolite, Pulmocare, Citrotein, Resource, Vivonex TEN, Vital, and Hepatic Acid II. Protein (10 and 20 g/liter) was added to Citrotein and Ensure Plus. All formulas were tested at full and some at half strength. Clotting occurred only in premixed intact protein formulas (Pulmocare, Ensure Plus, Osmolite, Enrich, Ensure) and in Resource. No clotting was observed for Citrotein (intact protein formula in powder form), Vital, Vivonex TEN, and Hepatic Aid II. Adding protein did not cause or increase clotting. In summary, clotting of some liquid formula diet appears to be an important factor causing possible gastric feeding tube occlusion. The following measures may help in preventing this problem: flushing before and after aspirating for gastric residuals to eliminate acid precipitation of formula in the feeding tube, advance the nasogastric feeding tube into the duodenum if possible, and avoid mixing these products with liquid medications having a pH value of 5.0 or less. PMID:3138452

  18. Traveling-Wave Tubes

    Science.gov (United States)

    Kory, Carol L.

    1998-01-01

    The traveling-wave tube (TWT) is a vacuum device invented in the early 1940's used for amplification at microwave frequencies. Amplification is attained by surrendering kinetic energy from an electron beam to a radio frequency (RF) electromagnetic wave. The demand for vacuum devices has been decreased largely by the advent of solid-state devices. However, although solid state devices have replaced vacuum devices in many areas, there are still many applications such as radar, electronic countermeasures and satellite communications, that require operating characteristics such as high power (Watts to Megawatts), high frequency (below 1 GHz to over 100 GHz) and large bandwidth that only vacuum devices can provide. Vacuum devices are also deemed irreplaceable in the music industry where musicians treasure their tube-based amplifiers claiming that the solid-state and digital counterparts could never provide the same "warmth" (3). The term traveling-wave tube includes both fast-wave and slow-wave devices. This article will concentrate on slow-wave devices as the vast majority of TWTs in operation fall into this category.

  19. Limited approach to the right flank for placement of a duodenostomy tube.

    Science.gov (United States)

    Novo, R E; Churchill, J; Faudskar, L; Lipowitz, A J

    2001-01-01

    A new enterostomy tube placement technique is described for provision of nutrients into the duodenum. Placement of the duodenostomy tube (d-tube) is performed through a limited right flank approach under sedation and local anesthesia. Seven client-owned animals (three dogs and four cats) requiring enteral nutritional support were selected for d-tube placement. Patients were fed via the d-tube for two to 28 days. Complications included discomfort when manipulating and exteriorizing the duodenum, discomfort with bolus feedings, local cellulitis, and tube site infection. All complications resolved without further incident. This technique should be considered in patients that are not good candidates for prolonged general anesthesia or esophageal or gastric feeding, or patients being mechanically ventilated. PMID:11300529

  20. CRL X-RAY TUBE

    OpenAIRE

    Kolchevsky, N. N.; Petrov, P. V.

    2015-01-01

    A novel types of X-ray tubes with refractive lenses are proposed. CRL-R X-ray tube consists of Compound Refractive Lens- CRL and Reflection X-ray tube. CRL acts as X-ray window. CRL-T X-ray consists of CRL and Transmission X-ray tube. CRL acts as target for electron beam. CRL refractive lens acts as filter, collimator, waveguide and focusing lens. Properties and construction of the CRL X-ray tube are discussed.

  1. Spectrometer beam tube dimensional optimization

    International Nuclear Information System (INIS)

    This project examined the optimization of the design of a beam tube. An ANSYS model was used to find the minimum tube thickness and the best camber in a beam tube under vacuum and preloaded by a pair of magnet poles. After the tube was modeled one version of it was built for use in the accelerator. This beam tube was put under a vacuum and the dimensional changes were recorded and compared to the ANSYS predictions. These deflection results were quite close to the predicted numbers and would suggest that the stresses are similar to the predictions as well

  2. 基于氧化膜生成速度和剥落厚度的600MW超临界锅炉高温过热器安全性分析%Analysis on Safety of High Temperature Super-heater in 600 MW Supercritical Boiler Based on Growth Rate and Spalling Depth of Oxidation Film

    Institute of Scientific and Technical Information of China (English)

    谢建文; 孙平; 李涛; 杨红权; 周克毅

    2011-01-01

    金属蒸汽侧氧化膜的生长和剥落对超临界或超超临界锅炉高温受热面的安全性有直接影响。以2台600MW超临界锅炉为对象,详细分析因蒸汽侧氧化膜剥落所导致的高温过热器爆管事故,介绍实际运行中所采取的提高高温受热面安全性的技术措施。在此基础上,以T91和TP347HFG管材为例,针对设备改造设计提出基于金属蒸汽侧氧化膜生长和剥落规律评价高温受热面金属安全性的方法,并应用于这2台锅炉高温过热器的实际改造方案的安全性评价,评价结果表明改造方案可以实现高温过热器在一个大修期内安全运行的预定目标,同时给出进一步优化改造方案的建议。研究结果对于制定锅炉检修计划和安全运行技术措施具有指导意义。%The growth and spalling of steam-side oxide scale have direct effects on the operation safety of high- temperature heating surfaces in supercritical or ultra- supercritical boilers. The accidents leading to the rupture of high temperature super-heater tubes induced by the spalling of oxide scale were analyzed on the basis of two 600 MW supercritical boilers, and technical measures adopted in practical operation were also introduced in detail. As for the retrofit design, measures considering the growth and spaUing mechanism of steam-side scale for the evaluation of the metal safety were presented with the cases of T91 and TP347HFG tubes, the evaluation result is that high temperature super- heater tubes of two 600 MW supercritical boilers should be safe in a overhaul period after retrofit, and suggestions for the further optimization were also proposed. The research can provide valuable reference for the safety operation and the establishment of the boiler scheduled maintenance procedure.

  3. Reliability of steam generator tubing

    Energy Technology Data Exchange (ETDEWEB)

    Kadokami, E. [Mitsubishi Heavy Industries Ltd., Hyogo-ku (Japan)

    1997-02-01

    The author presents results on studies made of the reliability of steam generator (SG) tubing. The basis for this work is that in Japan the issue of defects in SG tubing is addressed by the approach that any detected defect should be repaired, either by plugging the tube or sleeving it. However, this leaves open the issue that there is a detection limit in practice, and what is the effect of nondetectable cracks on the performance of tubing. These studies were commissioned to look at the safety issues involved in degraded SG tubing. The program has looked at a number of different issues. First was an assessment of the penetration and opening behavior of tube flaws due to internal pressure in the tubing. They have studied: penetration behavior of the tube flaws; primary water leakage from through-wall flaws; opening behavior of through-wall flaws. In addition they have looked at the question of the reliability of tubing with flaws during normal plant operation. Also there have been studies done on the consequences of tube rupture accidents on the integrity of neighboring tubes.

  4. Microdischarges in DC accelerator tubes

    International Nuclear Information System (INIS)

    Voltage tests on the Daresbury ceramic/titanium accelerator tube have shown that microdischarges play an important role in the conditioning process. It has been found that the voltage onset for microdischarges in a tube is dependent on the surface contamination of the electrodes and the tube geometry (in particular the tube length). This geometrical effect can be related to the trajectories of secondary ions emitted from the electrode surfaces. Sensitive diagnostic techniques have been developed to study the mass and energy distribution of ions emitted along the axis of the tube during these predischarges. The energy distribution of protons (and H- ions) can be related to the origins of the discharges in the tube. Detailed results are presented for a particular tube geometry. (author)

  5. Investigations of structural transformation within metal (austenite chromium-manganese steel) at the external surface of steam superheating tubes

    Science.gov (United States)

    Bogachev, V. A.; Pshechenkova, T. P.; Shumovskaya, M. A.

    2016-04-01

    The elemental composition of an altered layer at the external surface of a steam superheating tube of grade DI59 steel is investigated after long-term operation. It is shown that the layer is located between a scale and a matrix and depleted by silicon, manganese, copper, and chromium with the maximum oxidizer affinity, enriched by iron and nickel to 90%, and mainly composed of the α-Fe phase (ferrite) with the ferromagnetic properties. The layer formed as a result of selective oxidation and diffusion from the matrix into the metal scale with the less standard free energy of the formation of sulfides and oxides. A magnetic ferrite meter is used in the experimental investigation of the layer evolution by testing grade DI59 steel for heat resistance in air environment at temperatures of 585, 650, and 700°C for 15 × 103 h; creep at a temperature of 750°C and a stress of 60 MPa; and long-term strength at temperatures of 700 and 750°C and stresses of from 30 to 80 MPa. Specimens for tests are made of tubes under as-received conditions. The relationship between the ferrite phase content in the surface metal layer and the temperature and time of test is determined. The dependence is developed to evaluate the equivalent temperature for operation of the external surface of steam superheating tubes using data of magnetic ferritometry. It is shown that operation temperatures that are determined by the ferrite phase content and the σ phase concentration in the metal structure of steam superheating tubes with the significant operating time are close. It is proposed to use magnetic ferritometry for revelation of thermal nonuniformity and worst tubes of steam superheaters of HPP boilers.

  6. Ultrasonic inspection of tube to tube plate welds

    International Nuclear Information System (INIS)

    To monitor the deterioration of a weld between a tube and tube plate which has been repaired by a repair sleeve inside the tube and brazed at one end to the tube, ultrasound from a crystal at the end of a rod is launched, in the form of Lamb-type waves, into the tube through the braze and allowed to travel along the tube to the weld and be reflected back along the tube. The technique may also be used for the type of heat exchanger in which, during construction, the tubes are welded to the tube plate via external sleeves in which case the ultrasound is used in a similar manner to inspect the sleeve/tube plate weld. an electromagnetic transducer may be used to generate the ultrasound. The ultrasonic head comprising the crystal and an acoustic baffle is mounted on a Perspex (RTM) rod which may be rotated by a stepping motor. Echo signals from the region of deterioration may be isolated by use of a time gate in the receiver. The device primarily detects circumferentially orientated cracks, and may be used in heat exchangers in nuclear power plants. (author)

  7. Properties of thick welded joints on superheater collectors made from new generation high alloy martensitic creep-resisting steels for supercritical parameters

    Energy Technology Data Exchange (ETDEWEB)

    Dobrzanski, Janusz; Zielinski, Adam [Institute for Ferrous Metallurgy, Gliwice (Poland); Pasternak, Jerzy [Boiler Engineering Company RAFAKO S.A., Raciborz (Poland)

    2010-07-01

    The continuously developing power generation sector, including boilers with supercritical parameters, requires applications of new creep-resistant steel grades for construction of boilers steam superheater components. This paper presents selected information, experience within the field of research and implementation of a new group of creep-resistant as X10CrMoVNb9-1(P91), X10CrWMoVNb9-2(P92) and X12CrCoWVNb12-2-2(VM12) grades, containing 9-12%Cr. During welding and examination process the results of mechanical properties, requested level for base material and welded joints, as well as: tensile strength, impact strength and technological properties have been evaluated. Additional destructive examinations, with evaluation of structure stability, hardness distribution, for base material and welded joints after welding, heat treatment, again process have been determined. Recommendations due to the implementation influence of operating parameters of the main boiler components are part of this paper. (orig.)

  8. Candidate gene prioritization with Endeavour.

    Science.gov (United States)

    Tranchevent, Léon-Charles; Ardeshirdavani, Amin; ElShal, Sarah; Alcaide, Daniel; Aerts, Jan; Auboeuf, Didier; Moreau, Yves

    2016-07-01

    Genomic studies and high-throughput experiments often produce large lists of candidate genes among which only a small fraction are truly relevant to the disease, phenotype or biological process of interest. Gene prioritization tackles this problem by ranking candidate genes by profiling candidates across multiple genomic data sources and integrating this heterogeneous information into a global ranking. We describe an extended version of our gene prioritization method, Endeavour, now available for six species and integrating 75 data sources. The performance (Area Under the Curve) of Endeavour on cross-validation benchmarks using 'gold standard' gene sets varies from 88% (for human phenotypes) to 95% (for worm gene function). In addition, we have also validated our approach using a time-stamped benchmark derived from the Human Phenotype Ontology, which provides a setting close to prospective validation. With this benchmark, using 3854 novel gene-phenotype associations, we observe a performance of 82%. Altogether, our results indicate that this extended version of Endeavour efficiently prioritizes candidate genes. The Endeavour web server is freely available at https://endeavour.esat.kuleuven.be/. PMID:27131783

  9. Empathy Development in Teacher Candidates

    Science.gov (United States)

    Boyer, Wanda

    2010-01-01

    Using a grounded theory research design, the author examined 180 reflective essays of teacher candidates who participated in a "Learning Process Project," in which they were asked to synthesize and document their discoveries about the learning process over the course of a completely new learning experience as naive learners. This study explored…

  10. Candidate Prediction Models and Methods

    DEFF Research Database (Denmark)

    Nielsen, Henrik Aalborg; Nielsen, Torben Skov; Madsen, Henrik;

    2005-01-01

    This document lists candidate prediction models for Work Package 3 (WP3) of the PSO-project called ``Intelligent wind power prediction systems'' (FU4101). The main focus is on the models transforming numerical weather predictions into predictions of power production. The document also outlines the...

  11. Development of a double-wall-tube steam generator. Evaluation of thermal hydraulic tests on high mass flow rate condition

    International Nuclear Information System (INIS)

    The objectives of the 1MW test model of Double-Wall-Tube Steam Generator (DWT-SG) are to evaluate the thermal hydraulic performance and structural integrity such as heat transfer property, hydrodynamic instability property, DNB temperature fluctuation and capacity of leak detection for the elimination of the secondary sodium loop of FBR Plant. This report describes the heat transfer and hydrodynamic instability characteristic of DWT-SG on high water mass velocity (approximately 400∼900 kg/m2sec) condition by tube plugging. Main results are followings: [Heat Transfer Characteristic] Evaluation of the tests clarified the sodium and water/steam side heat transfer coefficient and DNB quality correlations. Under normal output condition, the tube plugging induced no buckling of the tubes caused by temperature difference and no disproportionate sodium temperature distribution. (1) Sodium side heat transfer coefficient remains almost unchanged after tube plugging. Graber-Rieger's equation is better to be applied to this reigion than the other equations. (2) DNB quality of high mass velocity is also same as that of low mass velocity, Kon'kov's equation used for Phenix SG can predict experimental results in 20% errors. (3) As for pre-heat region, Dittus-Boelter's equation can predict experimental results in 20% errors in high mass velocity. But the heat transfer coefficient of this equation is larger than the experimental data in low mass velocity. (4) The experimental heat transfer coefficient of nucleate boiling region has a wide range, therefore it is very difficult to derive an experimental equation. Jens-Lottes' and Thom's equations are in the order of experimental resaluts. (5) The range of the experimental heat transfer coefficient of film boiling region is a little wide, Mod. Tong's equation is better to be applied to this region than the other equations. (6) As for super-heat region, Bishop's equation can predict experimental results in 20% errors in high mass

  12. Steam generator tube integrity program

    Energy Technology Data Exchange (ETDEWEB)

    Dierks, D.R.; Shack, W.J. [Argonne National Laboratory, IL (United States); Muscara, J.

    1996-03-01

    A new research program on steam generator tubing degradation is being sponsored by the U.S. Nuclear Regulatory Commission (NRC) at Argonne National Laboratory. This program is intended to support a performance-based steam generator tube integrity rule. Critical areas addressed by the program include evaluation of the processes used for the in-service inspection of steam generator tubes and recommendations for improving the reliability and accuracy of inspections; validation and improvement of correlations for evaluating integrity and leakage of degraded steam generator tubes, and validation and improvement of correlations and models for predicting degradation in steam generator tubes as aging occurs. The studies will focus on mill-annealed Alloy 600 tubing, however, tests will also be performed on replacement materials such as thermally-treated Alloy 600 or 690. An overview of the technical work planned for the program is given.

  13. Sealed ion accelerator tubes (survey)

    International Nuclear Information System (INIS)

    The first publications on developing commercial models of small-scale sealed accelerator tubes in which neutrons are generated appeared in the foreign press in 1954 to 1957; they were very brief and were advertising-oriented. The tubes were designed for neutron logging of oil wells instead of ampule neutron sources (Po + Be, Ra + Be). Later, instruments of this type began to be called neutron tubes from the resulting neutron radiation that they gave off. In Soviet Union a neutron tube was developed in 1958 in connection with the development of the pulsed neutron-neutron method of studying the geological profile of oil wells. At that time the tube developed was intended, in the view of its inventors, to replace standard isotope sources with constant neutron yield. A fairly detailed survey of neutron tubes was made in the studies. 8 refs., 8 figs

  14. Multianode photomultiplier tube studies for imaging applications

    International Nuclear Information System (INIS)

    Highly efficient and position sensitive photon detection is essential in a variety of applications from particle identification in fundamental nuclear and particle physics research, to radionuclide imaging in healthcare. Due to their position sensitivity and high packing fraction, the Hamamatsu H8500 and H9500 multianode photomultiplier tubes (MAPMTs) are promising candidates for such applications and have thus been studied through precision laser scans at several light intensities. This has revealed signal and crosstalk dependencies upon constructional features of the MAPMTs. Both MAPMTs feature a common last dynode output signal, which can be used for self-triggering. The strength and timing of this signal have been investigated for the H8500 MAPMT, yielding similar dependencies upon MAPMT construction and standard deviation time resolutions of 67.5 ps and 154.4 ps for 20 and single photoelectron signals respectively.

  15. Alternate tube plugging criteria for steam generator tubes

    Energy Technology Data Exchange (ETDEWEB)

    Cueto-Felgueroso, C.; Aparicio, C.B. [Tecnatom, S.A., Madrid (Spain)

    1997-02-01

    The tubing of the Steam Generators constitutes more than half of the reactor coolant pressure boundary. Specific requirements governing the maintenance of steam generator tubes integrity are set in Plant Technical Specifications and in Section XI of the ASME Boiler and Pressure Vessel Code. The operating experience of Steam Generator tubes of PWR plants has shown the existence of some types of degradatory processes. Every one of these has an specific cause and affects one or more zones of the tubes. In the case of Spanish Power Plants, and depending on the particular Plant considered, they should be mentioned the Primary Water Stress Corrosion Cracking (PWSCC) at the roll transition zone (RTZ), the Outside Diameter Stress Corrosion Cracking (ODSCC) at the Tube Support Plate (TSP) intersections and the fretting with the Anti-Vibration Bars (AVBs) or with the Support Plates in the preheater zone. The In-Service Inspections by Eddy Currents constitutes the standard method for assuring the SG tubes integrity and they permit the monitoring of the defects during the service life of the plant. When the degradation reaches a determined limit, called the plugging limit, the SG tube must be either repaired or retired from service by plugging. Customarily, the plugging limit is related to the depth of the defect. Such depth is typically 40% of the wall thickness of the tube and is applicable to any type of defect in the tube. In its origin, that limit was established for tubes thinned by wastage, which was the predominant degradation in the seventies. The application of this criterion for axial crack-like defects, as, for instance, those due to PWSCC in the roll transition zone, has lead to an excessive and unnecessary number of tubes being plugged. This has lead to the development of defect specific plugging criteria. Examples of the application of such criteria are discussed in the article.

  16. The effect of inlet and outlet shell-side flow and heat transfer on the performance of HTGR straight tube heat exchangers

    International Nuclear Information System (INIS)

    Since the mid-1970s, various high temperature gas-cooled reactor (HTGR) steam generator, auxiliary heat exchanger (AHE), recuperator, and intermediate heat exchanger (IHX) designs have been proposed that use straight tube configurations. Each of these designs requires 90-deg turns in the helium gas flow at the inlet and/or outlet of the tube bundle. The design of the steam generator for the HTGR steam cycle/cogeneration lead plant includes a straight tube superheater (STSH) which incorporates both a 90-deg inlet and outlet turn across the tube bundle. The AHE includes a 90-deg outlet turn across the tube bundle. Previous GA Technologies Inc. (GA) recuperator and IHX designs for gas turbine and process heat HTGRs have also considered straight tube designs with 90-deg bends at the inlet and outlet. To evaluate the effect of these turns on the tube bundle performance, two model air flow tests have been performed, and a third is being planned. Fluid flow and heat transfer computer models have also been used to try to determine the effect of these 90-deg turns on the tube bundle performance. As a result of these studies, the following conclusions can be made: 1. For all of the designs investigated, the 90-deg turns reduced the bundle performance. 2. In designs where the tube pitch-to-diameter ratio is small (less than 1.3), the 90-deg turns can have a critical effect on the performance. However, use of design concepts such a flow baffles or small modular bundle designs can greatly reduce or eliminate these problems. 3. The inlet turns are more critical to the design than the outlet turns. 4. The non-uniform temperature profiles resulting from poor inlet design can result in high thermal stresses in the tubes. 5. Testing to correlate the shell-side heat transfer in the region of a 90-deg bend across a tube bundle is required to more fully understand the characteristics of this problem. 6. Although the 90-deg turns are not desirable, they are frequently necessary in

  17. Electron tubes for industrial applications

    Science.gov (United States)

    Gellert, Bernd

    1994-05-01

    This report reviews research and development efforts within the last years for vacuum electron tubes, in particular power grid tubes for industrial applications. Physical and chemical effects are discussed that determine the performance of todays devices. Due to the progress made in the fundamental understanding of materials and newly developed processes the reliability and reproducibility of power grid tubes could be improved considerably. Modern computer controlled manufacturing methods ensure a high reproducibility of production and continuous quality certification according to ISO 9001 guarantees future high quality standards. Some typical applications of these tubes are given as an example.

  18. Dermatology on YouTube

    OpenAIRE

    Boyers, Lindsay N.; Quest, Tyler; Karimkhani, Chante; Connett, Jessica; Dellavalle, Robert P.

    2014-01-01

    YouTube, reaches upwards of six billion users on a monthly basis and is a unique source of information distribution and communication. Although the influence of YouTube on personal health decision-making is well established, this study assessed the type of content and viewership on a broad scope of dermatology related content on YouTube. Select terms (i.e. dermatology, sun protection, skin cancer, skin cancer awareness, and skin conditions) were searched on YouTube. Overall, the results inclu...

  19. YouTube and 'psychiatry'.

    Science.gov (United States)

    Gordon, Robert; Miller, John; Collins, Noel

    2015-12-01

    YouTube is a video-sharing website that is increasingly used to share and disseminate health-related information, particularly among younger people. There are reports that social media sites, such as YouTube, are being used to communicate an anti-psychiatry message but this has never been confirmed in any published analysis of YouTube clip content. This descriptive study revealed that the representation of 'psychiatry' during summer 2012 was predominantly negative. A subsequent smaller re-analysis suggests that the negative portrayal of 'psychiatry' on YouTube is a stable phenomenon. The significance of this and how it could be addressed are discussed. PMID:26755987

  20. Learning from YouTube [Video Book

    Science.gov (United States)

    Juhasz, Alexandra

    2011-01-01

    YouTube is a mess. YouTube is for amateurs. YouTube dissolves the real. YouTube is host to inconceivable combos. YouTube is best for corporate-made community. YouTube is badly baked. These are a few of the things Media Studies professor Alexandra Juhasz (and her class) learned about YouTube when she set out to investigate what actually happens…

  1. IAEA Director General candidates announced

    International Nuclear Information System (INIS)

    Full text: The IAEA today confirms receipt of the nomination of five candidates for Director General of the IAEA. Nominations of the following individuals have been received by the Chairperson of the IAEA Board of Governors, Ms. Taous Feroukhi: Mr. Jean-Pol Poncelet of Belgium; Mr. Yukiya Amano of Japan; Mr. Ernest Petric of Slovenia; Mr. Abdul Samad Minty of South Africa; and Mr. Luis Echavarri of Spain. The five candidates were nominated in line with a process approved by the Board in October 2008. IAEA Director General Mohamed ElBaradei's term of office expires on 30 November 2009. He has served as Director General since 1997 and has stated that he is not available for a fourth term of office. (IAEA)

  2. Repair technology for steam generator tubes

    Energy Technology Data Exchange (ETDEWEB)

    Kim, Seung Ho; Jung, Hyun Kyu; Jung, Seung Ho; Kim, Chang Hoi; Jung, Young Moo; Seo, Yong Chil; Kim, Jung Su; Seo, Moo Hong

    2001-02-01

    The most commonly used sleeving materials are thermally treated Alloy 600 and thermally treated Alloy 690 Alloy. Currently, thermally treated Alloy 690 and Alloy 800 are being offered although Alloy 800 has not been licensed in the US. To install sleeve, joint strength, leak tightness, PWSCC resistance, evaluation on process parameter range and the effect of equipments and procedures on repair plan and radiation damage have to be investigated before sleeving. ABB CE provides three type of leak tight Alloy 690 TIG welded and PLUSS sleeve. Currently, Direct Tube Repair technique using Nd:YAG laser has been developed by ABB CE and Westinghouse. FTI has brazed and kinetic sleeve designs for recirculating steam generator and hydraulic and rolled sleeve designs for one-through steam generators. Westinghouse provides HEJ, brazed and laser welded sleeve design. When sleeve is installed in order to repair the damaged S/G tubes, it is certain that defects can be occurred due to the plastic induced stress and thermal stress. Therefore it is important to minimize the residual stress. FTI provides the electrosleeve technique as a future repair candidate using electroplating.

  3. Repair technology for steam generator tubes

    International Nuclear Information System (INIS)

    The most commonly used sleeving materials are thermally treated Alloy 600 and thermally treated Alloy 690 Alloy. Currently, thermally treated Alloy 690 and Alloy 800 are being offered although Alloy 800 has not been licensed in the US. To install sleeve, joint strength, leak tightness, PWSCC resistance, evaluation on process parameter range and the effect of equipments and procedures on repair plan and radiation damage have to be investigated before sleeving. ABB CE provides three type of leak tight Alloy 690 TIG welded and PLUSS sleeve. Currently, Direct Tube Repair technique using Nd:YAG laser has been developed by ABB CE and Westinghouse. FTI has brazed and kinetic sleeve designs for recirculating steam generator and hydraulic and rolled sleeve designs for one-through steam generators. Westinghouse provides HEJ, brazed and laser welded sleeve design. When sleeve is installed in order to repair the damaged S/G tubes, it is certain that defects can be occurred due to the plastic induced stress and thermal stress. Therefore it is important to minimize the residual stress. FTI provides the electrosleeve technique as a future repair candidate using electroplating

  4. VALUE ORIENTATIONS OF TEACHER CANDIDATES

    OpenAIRE

    YAPICI, Asım; KUTLU, M.Oğuz; BİLİCAN, F.Işıl

    2012-01-01

    Abstract This cross-sectional, descriptive study examined the change in values in time among teacher candidates. The Schwartz Values Inventory was administered to 708 freshmen and senior students studying at Cukurova University, Education Faculty. The results have shown that the students at the department of Science Education valued power, achievement, stimulation; the department of English Teaching Education valued hedonism; and the department of Education of Religious Culture valued un...

  5. Nasogastric tube syndrome induced by an indwelling long intestinal tube.

    Science.gov (United States)

    Sano, Naoki; Yamamoto, Masayoshi; Nagai, Kentaro; Yamada, Keiichi; Ohkohchi, Nobuhiro

    2016-04-21

    The nasogastric tube (NGT) has become a frequently used device to alleviate gastrointestinal symptoms. Nasogastric tube syndrome (NTS) is an uncommon but potentially life-threatening complication of an indwelling NGT. NTS is characterized by acute upper airway obstruction due to bilateral vocal cord paralysis. We report a case of a 76-year-old man with NTS, induced by an indwelling long intestinal tube. He was admitted to our hospital for treatment of sigmoid colon cancer. He underwent sigmoidectomy to release a bowel obstruction, and had a long intestinal tube inserted to decompress the intestinal tract. He presented acute dyspnea following prolonged intestinal intubation, and bronchoscopy showed bilateral vocal cord paralysis. The NGT was removed immediately, and tracheotomy was performed. The patient was finally discharged in a fully recovered state. NTS be considered in patients complaining of acute upper airway obstruction, not only with a NGT inserted but also with a long intestinal tube. PMID:27099450

  6. Explosive welding of a tube into a tube sheet

    Science.gov (United States)

    Green, Sheryll C.; Linse, Vonne D.

    1978-10-03

    A cartridge containing an explosive charge is placed within a tube assembled within a tube sheet. The charge is detonated through use of a detonator cord containing a minimum but effective amount of explosive material. The cord is contained inside a tubular shield throughout most of its length within the cartridge. A small length of the cord extends beyond the tubular shield to contact and detonate the explosive charge in its rear portion near the cartridge base. The cartridge base is provided of substantial mass and thickness in respect to side and front walls of the cartridge to minimize bulging beyond the rear face of the tube sheet. For remote activation an electrically activated detonator of higher charge density than the cord is attached to the cord at a location spaced from the tube sheet, cartridge and tube.

  7. Jose Cabrera (Zorita) tube examination

    International Nuclear Information System (INIS)

    Jose Cabrera (Zorita) tube examination procedures are discussed. This plant continues to use phosphate water chemistry (sodium/phosphate ratio = 2.1). Three hot leg tube segments were pulled from the Jose Cabera (Zorita) plant in 1985. One tube had a field EC indication on the OD at the first tube support plate and the other two had field EC indications on their ID about 3 inches above the bottom of the tube sheet. All three tubes were initially sent to Battelle for preliminary NDE and decontamination. Segments of two tubes were sent to Westinghouse for destructive examination. The results of the laboratory eddy current and radiographic examinations are given. The results of the visual examinations are also given. The tube with OD indications was destructively examined and shallow intergranular pitting and intergranular attack, up to 2 mils deep, were found on the OD in the tube sheet region. Local areas of IGA, up to 5 mils deep, were found on the OD within the tube support plate region. A summary of this information together with supporting micrographs is given. It was hypothesized that a caustic crevice environment was the cause of this mild degradation. Shallow areas of thinning or wastage, up to 3 mils, were found just above the top of the tube sheet in the sludge pile region. Even more shallow wastage was found at the edges of support plate locations. This wastage is believed to be the remnant of early plant chemistry when a higher sodium/phosphate ratio and higher phosphate concentration were allowed

  8. Piezoelectric Rotary Tube Motor

    Science.gov (United States)

    Fisher, Charles D.; Badescu, Mircea; Braun, David F.; Culhane, Robert

    2011-01-01

    A custom rotary SQUIGGLE(Registered TradeMark) motor has been developed that sets new benchmarks for small motor size, high position resolution, and high torque without gear reduction. Its capabilities cannot be achieved with conventional electromagnetic motors. It consists of piezoelectric plates mounted on a square flexible tube. The plates are actuated via voltage waveforms 90 out of phase at the resonant frequency of the device to create rotary motion. The motors were incorporated into a two-axis postioner that was designed for fiber-fed spectroscopy for ground-based and space-based projects. The positioner enables large-scale celestial object surveys to take place in a practical amount of time.

  9. Chapter 11. Digestive tube

    International Nuclear Information System (INIS)

    Exploration of the digestive tube by radioactive tracers relates mainly to the functional study of certain digestion or absorption troubles. The tracer absorbed by the digestibe system was followed by counting of the stools, successive measurements of the plasma radioactivity, measurements of urinary elimination or uptake on a storage organ such as the liver in the case of vitamin B12, measurement of whole-body radioactivity for vitamin B12 and iron. The different isotopic techniques used to study intestinal absorption of lipids, proteins and aminoacids, vitamin B 12 and iron were described and their contribution to the detection of exudative enteropathies and digestive haemorrhage was shown. It was pointed out that the stomach is one of the organs most accessible to standard exploration techniques. The role of sup(99m)Tc in both the morphological exploration of stomach and the study of gastric secretion, of 51Cr and 129Cs in the study of gastric evacuation were demonstrated

  10. NEI You Tube Videos: Amblyopia

    Medline Plus

    Full Text Available ... Vision Research & Ophthalmology (DIVRO) Student Training Programs NEI Home About NEI Health Information News and Events Grants ... Research at NEI Education Programs Training and Jobs Home > NEI YouTube Videos > NEI YouTube Videos: Amblyopia NEI ...

  11. Gastrostomy feeding tube - pump - child

    Science.gov (United States)

    Feeding - gastrostomy tube - pump; G-tube - pump; Gastrostomy button - pump; Bard Button - pump; MIC-KEY - pump ... Gather supplies: Feeding pump (electronic or battery powered) Feeding set that matches the feeding pump (includes a feeding bag, drip chamber, roller clamp, ...

  12. Flaming on YouTube

    NARCIS (Netherlands)

    Moor, Peter J.; Heuvelman, Ard; Verleur, Ria

    2010-01-01

    In this explorative study, flaming on YouTube was studied using surveys of YouTube users. Flaming is defined as displaying hostility by insulting, swearing or using otherwise offensive language. Three general conclusions were drawn. First, although many users said that they themselves do not flame,

  13. Characterization of tube support alloys

    International Nuclear Information System (INIS)

    The involvement and relationship of carbon steel corrosion products in the tube denting phenomenon promoted an intensive research effort to: 1) understand, reproduce, and arrest the denting process, and 2) evaluate alternative tube support materials to provide additional corrosion resistance. The paper summarizes a corrosion testing program for the verification of type 405 stainless steel under acid or all volatile treatment conditions

  14. Development of advanced high reliable helical type double wall tube steam generator

    International Nuclear Information System (INIS)

    A helical-coil-type double wall tube filled with a wire mesh layer is proposed for a steam generator (SG) of a new-type fast-breeder reactor in Japan in order to further increase reliability in operation. This double wall tube consists of inner and outer tubes and a wire mesh layer between inner and outer tubes. In last fiscal year, following 2 R and D projects were planned and established. An in-service inspection (ISI) technology is required to put this double wall tube SG to practical use. We need to detect small defects on an outer surface of an outer tube during an insert of a sensor into an inner tube. A major candidate for this inspection is a remote field eddy current testing (RFECT). An objective of this development is to demonstrate a defect detection of a double wall tube with a wire mesh layer using a RFECT. In order to connect tubes for helical-coil length, we designed and made prototype welding device unit, executed survey welding examination and evaluated applicability by the test piece examination. (author)

  15. Bilamellar type streak tube design

    International Nuclear Information System (INIS)

    In ICF experiments, high dynamic range, high temporal and spatial resolution X-ray streak camera is a necessary diagnosis tool. To meet this requirement, a streak tube which uses bilamellar electrode lens and quadrupolar lens to focus electrons has been designed. This tube uses different ways to focus electrons in temporal axis and spatial axis. In temporal axis, it uses two effectively. The spatial resolution of this tube reaches 40 lp/mm even at the edge of photocathode, the temporal resolution is about 10 ps and the effective length of photocathode is 20 mm. Using different focusing ways in temporal and spatial directions, the tube will not focus electrons to a small spot, compared with conventional rotary and symmetric tubes, and thus its space charge effect is much weaker, and dynamic range is much larger. (authors)

  16. The rotating tubing hanger system

    International Nuclear Information System (INIS)

    Beam pump systems are among the most cost efficient artificial lift systems in the industry, assuming a long run time between pulling jobs to repair tubing failures caused by rod wear. The tubing string represents the second largest investment in the well. The longer the period of time the well can be kept on-line and producing between pulling jobs, the more efficient and cost effective is the beam pump system. This paper describes in detail the conception, development and implementation of a new system that extends tubing life on rod pumped wells. The system uses a very simple concept; rotate the tubing string to extend the length of time between tubing failures and the resultant pulling jobs. The system is powered directly from the walking beam and requires no additional power source; nor does the system use any additional energy

  17. HF electronic tubes. Technologies, grid tubes and klystrons

    International Nuclear Information System (INIS)

    This article gives an overview of the basic technologies of electronic tubes: cathodes, electronic optics, vacuum and high voltage. Then the grid tubes, klystrons and inductive output tubes (IOT) are introduced. Content: 1 - context and classification; 2 - electronic tube technologies: cathodes, electronic optics, magnetic confinement (linear tubes), periodic permanent magnet (PPM) focussing, collectors, depressed collectors; 3 - vacuum technologies: vacuum quality, surface effects and interaction with electrostatic and RF fields, secondary emission, multipactor effect, thermo-electronic emission; 4 - grid tubes: operation of a triode, tetrodes, dynamic operation and classes of use, 'common grid' and 'common cathode' operation, ranges of utilisation and limitations, operation of a tetrode on unadjusted load, lifetime of a tetrode, uses of grid tubes; 5 - klystrons: operation, impact of space charge, multi-cavity klystrons, interaction efficiency, extended interaction klystrons, relation between interaction efficiency, perveance and efficiency, ranges of utilization and power limitations, multi-beam klystrons and sheet beam klystrons, operation on unadjusted load, klystron band pass and lifetime, uses; 6 - IOT: principle of operation, ranges of utilisation and limitations, interaction efficiency and depressed collector IOT, IOT lifetime and uses. (J.S.)

  18. Conditioning and breakdown phenomena in accelerator tubes

    International Nuclear Information System (INIS)

    Important breakdown mechanisms in accelerator tubes are reviewed, and discharge phenomena in NEC tubes are deduced from the surface appearance of the electrodes and insulators of a used tube. Microphotos of these surfaces are shown

  19. Eddy current signal comparison for tube identification

    Science.gov (United States)

    Glass, S. W.; Vojvodic, R.

    2015-03-01

    Inspection of nuclear power plant steam generator tubes is required to justify continued safe plant operation. The steam generators consist of thousands of tubes with nominal diameters of 15 to 22mm, approximately 1mm wall thickness, and 20 to 30m in length. The tubes are inspected by passing an eddy current probe through the tubes from tube end to tube end. It is critical to know exactly which tube identification (row and column) is associated with each tube's data. This is controlled by a precision manipulator that provides the tube ID to the eddy current system. Historically there have been some instances where the manipulator incorrectly reported the tube ID. This can have serious consequences including lack of inspection of a tube, or if a pluggable indication is detected, the tube is likely to be mis-plugged thereby risking a primary to secondary leak.

  20. Eddy current signal comparison for tube identification

    International Nuclear Information System (INIS)

    Inspection of nuclear power plant steam generator tubes is required to justify continued safe plant operation. The steam generators consist of thousands of tubes with nominal diameters of 15 to 22mm, approximately 1mm wall thickness, and 20 to 30m in length. The tubes are inspected by passing an eddy current probe through the tubes from tube end to tube end. It is critical to know exactly which tube identification (row and column) is associated with each tube's data. This is controlled by a precision manipulator that provides the tube ID to the eddy current system. Historically there have been some instances where the manipulator incorrectly reported the tube ID. This can have serious consequences including lack of inspection of a tube, or if a pluggable indication is detected, the tube is likely to be mis-plugged thereby risking a primary to secondary leak

  1. Vidicon storage tube electrical input/output

    Science.gov (United States)

    Lipoma, P.

    1972-01-01

    Electrical data storage tube is assembled from standard vidicon tube using conventional amplification and control circuits. Vidicon storage tube is simple, inexpensive and has an erase and preparation time of less than 5 microseconds.

  2. Vacuum distribution in the Vivitron accelerating tube

    International Nuclear Information System (INIS)

    Outgassing and conductance performances of HVEC type accelerating tube sections are calculated, measured and discussed. Based on the proposed Vivitron terminal stripping arrangement and tube pumping system, the vacuum pressure distribution along the accelerating tube has been determined

  3. Plasma Sprayed Pour Tubes and Other Melt Handling Components for Use in Gas Atomization

    Energy Technology Data Exchange (ETDEWEB)

    Byrd, David; Rieken, Joel; Heidloff, Andy; Besser, Matthew; Anderson, Iver

    2011-04-01

    Ames Laboratory has successfully used plasma sprayed ceramic components made from yttria stabilized zirconia as melt pouring tubes for gas atomization for many years. These tubes have proven to be strong, thermal shock resistant and versatile. Various configurations are possible both internally and externally. Accurate dimensions are achieved internally with a machined fugitive graphite mandrel and externally by diamond grinding. The previous study of the effect of spray parameters on density was extended to determine the effect of the resulting density on the thermal shock characteristics on down-quenching and up-quenching. Encouraging results also prompted investigation of the use of plasma spraying as a method to construct a melt pour exit stopper that is mechanically robust, thermal shock resistant, and not susceptible to attack by reactive melt additions. The Ames Laboratory operates two close-coupled high pressure gas atomizers. These two atomizers are designed to produce fine and coarse spherical metal powders (5{mu} to 500{mu} diameter) of many different metals and alloys. The systems vary in size, but generally the smaller atomizer can produce up to 5 kg of powder whereas the larger can produce up to 25 kg depending on the charge form and density. In order to make powders of such varying compositions, it is necessary to have melt systems capable of heating and containing the liquid charge to the desired superheat temperature prior to pouring through the atomization nozzle. For some metals and alloys this is not a problem; however for some more reactive and/or high melting materials this can pose unique challenges. Figure 1 is a schematic that illustrates the atomization system and its components.

  4. A $55 Shock Tube for Simulated Blast Waves

    CERN Document Server

    Courtney, Elijah; Courtney, Michael

    2015-01-01

    Shock tubes are commonly employed to test candidate armor materials, validate numerical models, and conduct simulated blast experiments in animal models. As DoD interests desire to field wearable sensors as blast dosimeters, shock tubes may also serve for calibration and testing of these devices. The high blast pressures needed for experimental testing of candidate armors are unnecessary to test these sensors. An inexpensive, efficient, and easily available way of testing these pressure sensors is desirable. It is known that releasing compressed gas suddenly can create a repeatable shock front, and the pressures can be finely tuned by changing the pressure to which the gas is compressed. A Crosman 0.177 caliber air pistol was used (without loading any pellets) to compress and release air in one end of a 24 inch long 3/4 inch diameter standard pipe nipple to simulate a blast wave at the other end of the tube. A variable number of pumps were used to vary the peak blast pressure. As expected, the trials where 10...

  5. Promising new cryogenic seal candidate

    International Nuclear Information System (INIS)

    Of the five seal candidates considered for the main propellant system of the Space Shuttle, only one candidate, the fluoroplastic Halar, satisfied all tests including the critical LO2 impact test and the cryogenic compression sealability test. Radiation-cross-linked Halar is a tough, strong thermoplastic that not only endured one hundred 2200 N compression cycles at 83 K while mounted in a standard military O-ring gland without cracking or deforming, but improved in sealability as a result of this cycling. Although these Halar O-rings require much higher sealing forces (approximately 500 N) at room temperature than rubber O-rings, on cooling to cryogenic temperatures the required sealing force only doubles, whereas the sealing force for rubber O-rings increases eightfold. Although these Halar O-rings were inadequately cross-linked, they still exhibited promise as LO2-compatible cryogenic seals. It is expected that their high-temperature properties can be greatly improved by higher degrees of cross-linking (e.g., by 20 mrad of radiation) without compromising their already excellent low-temperature properties. A direct comparison should then be obtained between the best of the cross-linked Halar compounds and the current commercial cryogenic seal materials, filled Teflon and Kel-F

  6. Wastage-resistant characteristics of 12Cr steel tube material. Small leak sodium-water reaction test

    International Nuclear Information System (INIS)

    In the water leak accident of a steam generator designed for a sodium cooled reactor in the Feasibility Study, the localization of tube failure propagation by using an advanced water leak detector will be required from the viewpoints of the safety and economical efficiency of the plant. So far, the conventional knowledge and analytical tools have been used in the investigation and evaluation of water leak phenomenon; nevertheless, there was neither test data nor the study of quantitative evaluation on the corrosion behavior, so-called wastage-resistant characteristics, of 12Cr steel tube material in sodium-water reactions. Wastage tests for the 12Cr steel tube material were conducted in small water leaks by use of the Sodium-Water Reaction Test Rig (SWAT-1R), and the data of wastage rate were obtained in the parameter of water leak rate under the constant sodium temperature and distance between leak and target tubes. The test results lead to the following conclusions: (1) The wastage-resistibility of 12Cr steel is 1.6 times greater than that of 9Cr steel and is 2.7 times greater than that of 2.25Cr-1Mo steel. (2)The wastage-resistibility of 12Cr steel increases in smaller water leaks; especially in water leak rates of 1 g/sec or less, it is more excellent than that of SUS321 stainless steel used as Monju superheater tube material. (3) Based on the correlation of wastage rate for the 9Cr steel, the correlation for the 12Cr steel has been obtained to be used for the evaluation of tube failure propagation. As the correlation of wastage rate for the 12Cr steel is based on the correlation for the 9Cr steel, it gives enough conservatism in smaller water leaks. To serve in accurately evaluating the tube failure propagation in smaller water leaks, it is necessary to obtain new correlation of wastage rate for the 12Cr steel based on the data in the wide range of water leak rates. (author)

  7. Electronic components, tubes and transistors

    CERN Document Server

    Dummer, G W A

    1965-01-01

    Electronic Components, Tubes and Transistors aims to bridge the gap between the basic measurement theory of resistance, capacitance, and inductance and the practical application of electronic components in equipments. The more practical or usage aspect of electron tubes and semiconductors is given emphasis over theory. The essential characteristics of each main type of component, tube, and transistor are summarized. This book is comprised of six chapters and begins with a discussion on the essential characteristics in terms of the parameters usually required in choosing a resistor, including s

  8. PEG tubes: dealing with complications.

    Science.gov (United States)

    Malhi, Hardip; Thompson, Rosie

    A percutaneous endoscopic gastronomy tube can be used to deliver nutrition, hydration and medicines directly into the patient's stomach. Patients will require a tube if they are unable to swallow safely, putting them at risk of aspiration of food, drink and medicines into their lungs. It is vital that nurses are aware of the complications that may arise when caring for a patient with a PEG tube. It is equally important that nurses know how to deal with these complications or from where tc seek advice. This article provides a quick troubleshooting guide to help nurses deal with complications that can arise with PEG feeding. PMID:26016095

  9. High heat load test of CFC divertor target plate with screw tube for JT-60 superconducting modification

    International Nuclear Information System (INIS)

    A flat carbon fiber composite (CFC) tile mock-up with screw tubes, which have helical fins like a nut, was fabricated aiming at further improvement of the heat removal performance of the cost-effectively manufactured divert or target for JT-60SC (modified JT-60 as a superconducting coil tokamak). The heat removal performance of the mock-up was successfully demonstrated on the JAERI Electron Beam Irradiation Stand. The estimated heat transfer coefficient of the screw tube at the non-boiling region was roughly three times higher than that of the smooth tube. This corresponds to 1.5 times that of the swirl tube. A heat cycle test of 10 MW/m2 showed that the mock-up with the screw tubes could withstand for 1400-cycles. These results indicate that the divertor target plate with the flat CFC tile and the screw tube can be a promising candidate for the JT-60SC divertor target

  10. Consideration of alternative designs for a Percutaneous Endoscopic Gastrostomy feeding tube

    Science.gov (United States)

    Yerrabolu, Santosh Rohit

    The inability of some people to chew or swallow foods (but can digest foods) due to problems associated with various diseases and complications leads them to insufficient nutritional intake and loss of quality of life. These individuals are generally provided with nutritional support by means of injecting or infusing food directly into their stomachs or small intestines via feeding tubes. Gastrostomy feeding tubes (G-tubes) are used when such nutritional support is required for over 3-6 weeks. Percutaneous Endoscopic Gastrostomy (PEG) tubes are one of the most widely used G- Tubes and devices which are inserted via an incision through the abdominal wall either through a pull or push method. This investigation proposes conceptual alternative Percutaneous Endoscopy Gastrostomy (PEG) feeding tube designs with optimized materials selection to be used for their construction. The candidate materials were chosen from 18 commercial catheters, 2 reference grade polymers and a commercial polymer; using tissue-catheter-friction testing and surface chemistry characterization (Infrared spectroscopy and Critical Surface Tension approximation). The main objectives considered were to minimize slipping/dislodgement of gastrostomy tube/seal, to reduce peristomal leakage, and to attain size variability of PEG tubes while maintaining a low profile. Scanning Electron Microscope- Energy Dispersive X-ray Spectroscopy was employed to further determine the filler materials used in the samples. Nylon coated with fatty ester and filled with Barium sulphate was determined as the optimum material for the construction of the tube part of the feeding tubes to reduce slipping/dislodgment of gastrostomy tube/seal and to minimize peristomal leakage. Nylon coated with fatty ester and filled with Silica is the suggested as a candidate material for construction of the bumper/mushroom sections of the feeding tubes to avoid the Buried Bumper Syndrome. Fused Deposition Modeling, Selective Laser Sintering

  11. Numerical Modeling of Tube Forming by HPTR Cold Pilgering Process

    Science.gov (United States)

    Sornin, D.; Pachón-Rodríguez, E. A.; Vanegas-Márquez, E.; Mocellin, K.; Logé, R.

    2016-07-01

    For new fast-neutron sodium-cooled Generation IV nuclear reactors, the candidate cladding materials for the very strong burn-up are ferritic and martensitic oxide dispersion strengthened grades. Classically, the cladding tube is cold formed by a sequence of cold pilger milling passes with intermediate heat treatments. This process acts upon the geometry and the microstructure of the tubes. Consequently, crystallographic texture, grain sizes and morphologies, and tube integrity are highly dependent on the pilgering parameters. In order to optimize the resulting mechanical properties of cold-rolled cladding tubes, it is essential to have a thorough understanding of the pilgering process. Finite Element Method (FEM) models are used for the numerical predictions of this task; however, the accuracy of the numerical predictions depends not only on the type of constitutive laws but also on the quality of the material parameters identification. Therefore, a Chaboche-type law which parameters have been identified on experimental observation of the mechanical behavior of the material is used here. As a complete three-dimensional FEM mechanical analysis of the high-precision tube rolling (HPTR) cold pilgering of tubes could be very expensive, only the evolution of geometry and deformation is addressed in this work. The computed geometry is compared to the experimental one. It is shown that the evolution of the geometry and deformation is not homogeneous over the circumference. Moreover, it is exposed that the strain is nonhomogeneous in the radial, tangential, and axial directions. Finally, it is seen that the dominant deformation mode of a material point evolves during HPTR cold pilgering forming.

  12. Precise muon drift tube detectors for high background rate conditions

    Energy Technology Data Exchange (ETDEWEB)

    Engl, Albert

    2011-08-04

    The muon spectrometer of the ATLAS-experiment at the Large Hadron Collider consists of drift tube chambers, which provide the precise measurement of trajectories of traversing muons. In order to determine the momentum of the muons with high precision, the measurement of the position of the muon in a single tube has to be more accurate than {sigma}{<=}100 {mu}m. The large cross section of proton-proton-collisions and the high luminosity of the accelerator cause relevant background of neutrons and {gamma}s in the muon spectrometer. During the next decade a luminosity upgrade to 5.10{sup 34} cm{sup -2}s{sup -1} is planned, which will increase the background counting rates considerably. In this context this work deals with the further development of the existing drift chamber technology to provide the required accuracy of the position measurement under high background conditions. Two approaches of improving the drift tube chambers are described: - In regions of moderate background rates a faster and more linear drift gas can provide precise position measurement without changing the existing hardware. - At very high background rates drift tube chambers consisting of tubes with a diameter of 15 mm are a valuable candidate to substitute the CSC muon chambers. The single tube resolution of the gas mixture Ar:CO{sub 2}:N{sub 2} in the ratio of 96:3:1 Vol %, which is more linear and faster as the currently used drift gas Ar:CO{sub 2} in the ratio of 97:3 Vol %, was determined at the Cosmic Ray Measurement Facility at Garching and at high {gamma}-background counting rates at the Gamma Irradiation Facility at CERN. The alternative gas mixture shows similar resolution without background. At high background counting rates it shows better resolution as the standard gas. To analyse the data the various parts of the setup have to be aligned precisely to each other. The change to an alternative gas mixture allows the use of the existing hardware. The second approach are drift tubes

  13. NEI You Tube Videos: Amblyopia

    Medline Plus

    Full Text Available ... Funding Division of Extramural Affairs Division of Extramural Science Programs Funding Opportunity Announcements Funding Mechanisms Supported by ... Amaurosis Low Vision Refractive Errors Retinopathy of Prematurity Science Spanish Videos Webinars NEI YouTube Videos: Amblyopia NEI ...

  14. drift tube for linear accelerator

    CERN Multimedia

    A drift tube from the Linac 1. This was the first tank of the linear accelerator Linac1, the injection system for the Proton Synchrotron, It ran for 34 years (1958 - 1992). Protons entered at the far end and were accelerated between the copper drift tubes by an oscillating electromagnetic field. The field flipped 200 million times a second (200 MHz) so the protons spent 5 nanoseconds crossing a drift tube and a gap. Moving down the tank, the tubes and gaps had to get longer as the protons gained speed. The tank accelerated protons from 500 KeV to 10 MeV. Linac1 was also used to accelerate deutrons and alpha particles for the Intersecting Storage Rings and oxygen and sulpher ions for the Super Proton Synchrotron heavy ion programme.

  15. NEI You Tube Videos: Amblyopia

    Medline Plus

    Full Text Available ... Funding Division of Extramural Activities Division of Extramural Science Programs Funding Opportunity Announcements Funding Mechanisms Supported by ... Amaurosis Low Vision Refractive Errors Retinopathy of Prematurity Science Spanish Videos Webinars NEI YouTube Videos: Amblyopia NEI ...

  16. Lunar Core Drive Tubes Summary

    Data.gov (United States)

    National Aeronautics and Space Administration — Contains a brief summary and high resolution imagery from various lunar rock and core drive tubes collected from the Apollo and Luna missions to the moon.

  17. NEI You Tube Videos: Amblyopia

    Medline Plus

    Full Text Available ... NEI All Research at NEI Office of the Scientific Director Office of the Clinical Director Education Programs ... Amaurosis Low Vision Refractive Errors Retinopathy of Prematurity Science Spanish Videos Webinars NEI YouTube Videos: Amblyopia NEI ...

  18. NEI You Tube Videos: Amblyopia

    Medline Plus

    Full Text Available ... Amaurosis Low Vision Refractive Errors Retinopathy of Prematurity Science Spanish Videos Webinars NEI YouTube Videos: Amblyopia NEI ... questions and comments to the NEI Office of Science Communications, Public Liaison, and Education. Technical questions about ...

  19. Lattice tube model of proteins

    OpenAIRE

    Banavar, Jayanth R.; Cieplak, Marek; Maritan, Amos

    2004-01-01

    We present a new lattice model for proteins that incorporates a tube-like anisotropy by introducing a preference for mutually parallel alignments in the conformations. The model is demonstrated to capture many aspects of real proteins.

  20. NEI You Tube Videos: Amblyopia

    Medline Plus

    Full Text Available ... Eye Disease Dilated Eye Exam Dry Eye For Kids Glaucoma Healthy Vision Tips Leber Congenital Amaurosis Low Vision Refractive Errors Retinopathy of Prematurity Science Spanish Videos Webinars NEI YouTube Videos: Amblyopia NEI ...

  1. The YouTube reader

    OpenAIRE

    2009-01-01

    YouTube has come to epitomize the possibilities of digital culture. With more than seventy million unique users a month and approximately eighty million videos online, this brand-name video distribution platform holds the richest repository of popular culture on the Internet. As the fastest growing site in the history of the Web, YouTube promises endless new opportunities for amateur video, political campaigning, entertainment formats, and viral marketing—a clip culture that has seemed to out...

  2. Duplication of the fallopian tube

    Directory of Open Access Journals (Sweden)

    R Narayanan

    2008-01-01

    Full Text Available Hysterosalpingography accurately delineates the uterine and tubal lumen, and hence is routinely performed for the evaluation of infertility.We observed a case of infertility where uterine cavity was normal but fallopian tubes were bifurcated at the ampullary region. Mullerian duct anomalies are reported in literature, but maldevelopment of fallopian tube in isolation is rare. This abnormality can present as infertility, ectopic pregnancy, in association with urinary tract anomalies or as failure of sterilisation method.

  3. Eddy current tube testing unit

    International Nuclear Information System (INIS)

    The unit described can check a wide variety of tubes in quick succession and its modular design gives it a high degree of versability. Suitably defined working conditions and specific fittings enable most of the faults encountered in the manufacture of a tube to be detected. By appropriate means of selection based on signal amplitude, phase and frequency analyses it is possible to adapt selection criteria to the seriousness of the different categories of defect

  4. Energy dissipation in circular tube

    OpenAIRE

    A.D. Girgidov

    2012-01-01

    Energy dissipation distribution along the circular tube radius is important in solving such problems as calculation of heat transfer by the air flow through building envelope; calculation of pressure loss in spiral flows; calculation of cyclones with axial and tangential supply of dust-containing gas.Two types of one-dimensional radially axisymmetric flows in circular tube were considered: axial flow and rotation about the axis (Rankine vortex). Relying on two- and four-layer description of a...

  5. Test-tube Baby Option

    Institute of Scientific and Technical Information of China (English)

    2008-01-01

    As China’s first test tube baby celebrates her 20th birthday,the country is moving to improve IVF procedures I feel just like a normal person,despite being a little bit hi-tech,"said China’s first test-tube baby Zheng Mengzhu at her birthday party in Beijing. Zheng,born on March 10,1988 in the No.3 Hospital affiliated to the Peking University of Medical Sciences,made a trip

  6. Clinical study of urokinase-bound fibrocollagenous tubes.

    Science.gov (United States)

    Senatore, F; Bernath, F; Meisner, K

    1986-02-01

    Dacron-reinforced fibrocollagenous tubes (FCT) were synthesized from canine mongrels using the mandril-rod technique in order to develop a small diameter (i.e., 4 mm i.d.) vascular graft. They were rendered fibrinolytic by immobilizing urokinase on to the inner surface of the tubes. Urokinase-bound fibrocollagenous tubes (UK-FCT), control FCTs (i.e., no bound enzyme), Perloff grafts (Dr. Perloff, Department of Surgery, University Medical Center, Sidney Australia, has developed a mandril-derived collagenous tube from goats. Samples were implanted for comparative purposes.) and autogeneous saphenous veins, were interposed in the carotid or femoral artery in chronic studies involving 21 canine mongrels. On the basis of Doppler auscultation and palpation, the UK-FCTs were statistically more patent than other candidate prostheses. Fibrin degradation product (FDP) increased in the dogs' systemic circulation with a postoperative peak of 5 days. The host's increase in fibrinolytic activity was shown to be local to the anastamosis. A carotid arterial extracorporeal shunt was designed to evaluate acute patency. Results indicated a rapid thrombosis but no platlet or fibrin adherence to the graft surface was observed, as evidenced by scanning electron microscopy. PMID:2937788

  7. Constitutive modelling of dual phase steel sheet and tube

    Science.gov (United States)

    Thompson, A. C.; Salisbury, C. P.; Worswick, M. J.; Mayer, R.

    2006-08-01

    Automobile manufacturers are currently striving to improve vehicle fuel efficiency through reduction of vehicle weight. Dual phase steels are good candidates for automotive bodies due to their high strength-to-weight ratio, and good formablity and weldability. As part of a project on the interaction between forming and crashworthiness, constitutive parameters of a dual phase steel were determined for both sheet and tube stock in order to support analysis of the tube response throughout forming processes and in crash simulations. Stress - strain data was collected at a quasi-static rate as well as rates from 0.1 to 1500 s - 1. The intermediate strain rate response was captured using an instrumented falling weight tensile tester (35 100 s - 1), while a tensile split Hopkinson bar (500 1500 s - 1) was used to capture the high-rate response. This range of strain rates is typical of the rates seen in a crash simulation. Tests were also performed at higher temperatures (150°C and 300°C) at rates of 500 and 1500 s - 1 to capture the thermal softening response. The dual phase steel sheet and tube show an appreciable amount of strain rate sensitivity throughout the complete range of strain rates. It also exhibited a large amount of thermal softening. The thermal sensitivity is identical for the sheet and tube. Fits to the Johnson-Cook constitutive model were obtained from the experimental results.

  8. Tube-in-shell heat exchangers

    International Nuclear Information System (INIS)

    Tube-in-shell heat exchangers normally comprise a bundle of parallel tubes within a shell container, with a fluid arranged to flow through the tubes in heat exchange with a second fluid flowing through the shell. The tubes are usually end supported by the tube plates that separate the two fluids, and in use the tube attachments to the tube plates and the tube plates can be subject to severe stress by thermal shock and frequent inspection and servicing are required. Where the heat exchangers are immersed in a coolant such as liquid Na such inspection is difficult. In the arrangement described a longitudinally extending central tube is provided incorporating axially spaced cylindrical tube plates to which the opposite ends of the tubes are attached. Within this tube there is a tubular baffle that slidably seals against the wall of the tube between the cylindrical tube plates to define two co-axial flow ducts. These ducts are interconnected at the closed end of the tube by the heat exchange tubes and the baffle comprises inner and outer spaced walls with the interspace containing Ar. The baffle is easily removable and can be withdrawn to enable insertion of equipment for inspecting the wall of the tube and tube attachments and to facilitate plugging of defective tubes. Cylindrical tube plates are believed to be superior for carrying pressure loads and resisting the effects of thermal shock. Some protection against thermal shock can be effected by arranging that the secondary heat exchange fluid is on the tube side, and by providing a thermal baffle to prevent direct impingement of hot primary fluid on to the cylindrical tube plates. The inner wall of the tubular baffle may have flexible expansible region. Some nuclear reactor constructions incorporating such an arrangement are described, including liquid metal reactors. (U.K.)

  9. Evaluation of candidate photomultiplier tubes for the NOE scintillating fiber calorimeter

    CERN Document Server

    Barbarino, G C; Brigida, M; Campana, D; Candela, A; Caruso, R; Ceres, A; De Mitri, I; Di Credico, A; Favuzzi, C; Fusco, P; Gargano, F; Giglietto, N; Giordano, F; Grillo, A; Guarino, F; Leone, A; Lindozzi, M; Loparco, F; Mancarella, G; Mazziotta, M N; Mongelli, M; Osteria, G; Palladino, V; Perchiazzi, M; Pinto, C; Rain; Rain; Sacchetti, A; Scapparone, E; Spinelli, P; Zilli, A

    2002-01-01

    Several measurements have been made on different phototubes in order to select the type to be used for the readout system of the NOE magnetized scintillating fiber calorimeter. Characteristics such as gain, linearity, time resolution and cathode uniformity have been examined on several PMT types with standard, fine mesh or channel multiplier structure. The PMT response in the presence of the magnetized calorimeter fringe fields has also been studied. Here we report on the results of these measurements and of the comparisons between the different PMT types.

  10. Evaluation of candidate photomultiplier tubes for the NOE scintillating fiber calorimeter

    International Nuclear Information System (INIS)

    Several measurements have been made on different phototubes in order to select the type to be used for the readout system of the NOE magnetized scintillating fiber calorimeter. Characteristics such as gain, linearity, time resolution and cathode uniformity have been examined on several PMT types with standard, fine mesh or channel multiplier structure. The PMT response in the presence of the magnetized calorimeter fringe fields has also been studied. Here we report on the results of these measurements and of the comparisons between the different PMT types

  11. Cause Analysis of Superheater Desuperheating Water Regulating Valve Failure in Million Power Plant%百万电厂过热器减温水调节阀故障原因分析

    Institute of Scientific and Technical Information of China (English)

    张立德

    2014-01-01

    The one or two stage superheater desuperheating water regulating valve of the million power units has occurred the stuffing box leakage problems frequently in operation in Wenergy Tongling Power Generation Co ., Ltd..The desuperheating water regulating valves are analyzed , to find out the main rea-son .The results show that the stuffing box leakage mainly dues to the valve structure .The optimal control scheme is found through experiment .After taking corresponding measures , the good result is achieved , to provide a reference to handle the failure of the superheater desuperheating water regulating valve of large capacity units in power plant .%皖能铜陵发电厂百万机组一、二级过热器减温水调节阀在运行中频繁出现填料函泄漏的问题。对减温水调节阀进行分析,找出主要原因。结果表明:填料函泄漏主要源于阀门结构。通过实验找出最佳控制方案,采取相应措施后取得了很好的效果,可为处理电厂大容量机组过热器减温水系统调节阀故障提供参考借鉴。

  12. Failure analysis for second superheater tubes in a circulating fluidized bed boiler%某一循环流化床锅炉Ⅱ级过热器管材失效分析

    Institute of Scientific and Technical Information of China (English)

    邓化凌; 王勇; 宋云京; 陈玉华

    2006-01-01

    利用金相显微镜、扫描电镜(SEM)和定量光谱仪等对465 t/h循环流化床(CFB)锅炉Ⅱ级过热器管爆口进行了金相组织分析、宏观及微观形貌观察、材质化学成分以及结构和运行状况分析,探讨了过热器管材的失效原因和机理.结果表明,CFB锅炉内颗粒的冲刷与撞击造成过热器管屏的磨损,磨损引起的壁厚减薄是管材失效的主要原因,磨损机理主要是冲刷磨损和高温腐蚀相结合的冲蚀磨损;管子内压应力与管系应力加速了爆漏过程,是造成过热器管撕裂爆口的次要原因.

  13. CG-220/100M3型低温过热器失效分析及对策%Failure Analysis on Furnace Tube of CG-220/100M3 Type Low Temperature Superheater and its Countermeasure

    Institute of Scientific and Technical Information of China (English)

    陈峰; 丛培振; 徐国良; 严飞

    2004-01-01

    分析了CG-220/100M3型低温过热器失效的原因,在进行材料的成分、力学性能、材料组织、电镜分析的同时,结合运行寿命分析,认为失效的主要原因是烟气通道堵灰严重,形成烟气短路,导致部分炉管超温,发生高温蠕变损伤,在应力的作用下,形成蠕变孔洞,进而形成裂纹,从而导致最终的爆裂失效.根据分析的结果,提出了预防措施.

  14. 300 MW亚临界锅炉末级过热器爆管的分析及预防%Analysis and Prevention for Tube Failure of Final Superheater in 300 MW Subcritical Boiler

    Institute of Scientific and Technical Information of China (English)

    徐少峰; 彭福仁

    2009-01-01

    对300 MW亚临界锅炉启动初期发生的末级过热器爆管事件进行分析,排除长期超温过热和水塞过热的可能性后,得出氧化皮脱落堵塞过热是爆管的主要原因,并给出防范的建议.

  15. 锅炉过热器异种钢管接头失效分析%Failure analysis for the dissimilar metal joints of superheater tubes in power plant station

    Institute of Scientific and Technical Information of China (English)

    孟庆森; 罗光敏; 梁军; 薛锦

    2000-01-01

    神头二电厂过热器异种钢接头高温运行约4×104 h后,沿耐热钢HAZ发生了裂纹.经手弧焊修补,运行一段时间后再次出现裂纹.本文通过断口及金相分析表明,接头前期失效为蠕变失效,这可由耐热钢HAZ珠光体球化,碳化物聚集和碳迁移说明;接头后期失效为应力腐蚀失效,这可由存在的应力和含有Cl-的水蒸气共同作用导致.另外,接头焊接缺陷引起应力集中,也加速了SCC的产生.改进焊接工艺,采用镍基焊丝TIG焊的过渡接头可有效提高其蠕变强度和服役寿命.

  16. 1025t/h CFB锅炉屏式过热器管失效分析%Failure Analysis on Platen Superheater Tubes in 1 025 t/h CFB Boiler

    Institute of Scientific and Technical Information of China (English)

    杨庆旭; 杨超; 孙雄; 姚永灵

    2013-01-01

    某1 025 t/h CFB锅炉屏式过热器管多次发生靠近水冷壁前墙位置的爆漏,采用宏观检查、化学元素分析、显微组织分析及显微硬度分析等方法对屏式过热器管爆漏原因进行了试验与分析.结果表明:屏式过热器结构应力在靠近水冷壁前墙部位的叠加、屏式过热器管固定块焊缝的焊接质量不良以及启停炉过程中的应力循环等原因综合作用,导致固定块角焊缝低周高应力疲劳断裂,裂纹扩展至管子致使屏式过热器管爆漏.

  17. 670t/h锅炉高温过热器管爆裂失效分析%FAILURE ANALYSIS ON A SUPERHEATER TUBE OF 670t/h BOILER

    Institute of Scientific and Technical Information of China (English)

    李正刚; 廖金枝

    2006-01-01

    某电厂1号锅炉的高温过热器在运行中发生爆漏.采用化学成分分析、宏观检验和显微组织分析等方法对爆管进行了分析;同时对爆管内壁氧化膜厚度的动态变化进行了测定,并以此来估算其当量温度,最后计算出剩余寿命.结果表明,过热器爆漏的原因是长期过热造成的.提出了预防措施.

  18. Analysis on Tube Explosion and Failure of High Temperature Superheater of No 1 Boiler in Zhangping Power Plant%漳平电厂#1炉高温过热器爆管失效分析

    Institute of Scientific and Technical Information of China (English)

    蒋潇甫

    2003-01-01

    对漳平电厂#1炉高温过热器热段管排爆管事故进行分析,通过材质分析、拉伸试验、金相检查、内部检查并结合高温过热段进口联箱结构、动力场试验及运行工况进行分析,查找出事故原因,提出相应的预防措施.

  19. 1000MW 机组锅炉高温过热器爆管失效机理探讨%Discussion on Failure Mechanism of Tube Burst in High-temperature Superheater of 1 000 MW Boiler

    Institute of Scientific and Technical Information of China (English)

    董红年

    2011-01-01

    以潮州电厂3号锅炉(1 000 Mw 机组)高温过热器出口段爆管为例,取爆管附近颜色发生变化的管子进行拉力试样和金相分析试验,通过对比并结合现场情况,从过热、结构、管子加工工艺、晶粒度、热处理工艺、运行及热偏差等方面分析爆管失效的原因,并提出改进措施与建议.

  20. Temperature Deviation and Tube Failure of Rear Screen-type Superheater in 600MW Boiler%HG-2008/186型锅炉后屏过热器热偏差及管壁失效研究

    Institute of Scientific and Technical Information of China (English)

    张新生; 唐必光; 钱昌黔; 刘勇; 方晓东; 李永德

    2001-01-01

    针对平圩电厂HG-2008/186型锅炉后屏过热器的过热失效问题编制了壁温计算程序,并通过对部分管材的金相分析,对该过热器管壁失效状况及寿命进行了综合评价.

  1. Analysis of the Failure of a Collector Partition Plate from the Perspective of a Platen Superheater Tube Explosion and its Treatment%由屏过爆管看集箱隔板损坏及处理

    Institute of Scientific and Technical Information of China (English)

    赵维青

    2000-01-01

    某热电厂1号炉在试运行初期发生屏过爆管现象,经查:其原因是集箱内隔板开焊、变形、移位致汽流短路而超温.从隔板的结构以及运行中受力情况入手,分析了损坏原因,并介绍了返修方案.

  2. Bursting Failure Analysis of High Temperature Superheater Tube in a Power Plant Boiler%热电厂锅炉高温过热器管爆管原因

    Institute of Scientific and Technical Information of China (English)

    王金星; 刘天模; 冯大碧; 张力; 杨晓明; 唐昌发

    2009-01-01

    利用化学成分分析、力学性能测试、显微组织分析和X射线衍射物相分析等方法,对材料为T91钢的热电厂锅炉高温过热器管的爆管原因进行了分析.结果表明:高温过热器管材料的质量合格,异物阻塞管道造成其短时过热是过热器管爆管的主要原因,在距爆口一侧约30 cm处发现有异物残留.

  3. 锅炉低温过热器吊挂管断裂原因分析%Transverse rupture cause analysis of hanger tube of boiler low-temperature superheater

    Institute of Scientific and Technical Information of China (English)

    郑文超

    2015-01-01

    在某电厂扩建2×300 MW机组工程锅炉低温过热器吊挂管水平运输及吊装过程中,先后有7根吊挂管发生横向断裂,通过现场观测及各种试验与分析,确认低温过热器吊挂管横向断裂的原因为设备厂家提供的管母材冲击韧性过低和挂件焊缝不合格所致.

  4. Technological Transformation on Overtemperature Tube Rupture for High-temperature Superheater of Boiler%锅炉高温过热器超温爆管的技术改造

    Institute of Scientific and Technical Information of China (English)

    陈盛

    2006-01-01

    针对丰镇发电厂1号炉高温过热器超温问题,分别从试验测试、原因分析、改造方案简述、数据结果分析等几个方面进行总结,得出该技术改造的结论,并提出建议.

  5. 改调峰机组后锅炉高温过热器超温爆管的预防%Prevention of Peak Shaving Boiler Superheater Overheating tube Rupture

    Institute of Scientific and Technical Information of China (English)

    刘国强

    2003-01-01

    分析了DG410/100-2型锅炉高温过热器爆管的原因,重点对带基本负荷机组改调峰机组后锅炉出现的保持正常主汽温度与高温受热面超温的矛盾作了阐述,从检修与运行两方面对预防措施进行了探讨.

  6. 丰源4#锅炉过热器爆管的分析%Analysis of the Superheater Tube Rupture of the 4# Boiler in Fengyuan Power Plant

    Institute of Scientific and Technical Information of China (English)

    李民; 杨荣清; 王如超; 李文凯

    2003-01-01

    通过对过热器爆管的分析,论述了循环流化床锅炉在短时间压火后重新启炉时存在的后燃隐患,直接影响了过热器的使用寿命,甚至发生爆管;并提出了操作方面应采取的相应措施.

  7. Analysis on Tube Rupture in High Temperature Super-heater for 1 025 t/h Boiler%1 025 t/h锅炉高温过热器爆管原因分析

    Institute of Scientific and Technical Information of China (English)

    吴磊; 顾昌

    2004-01-01

    针对亚临界中间再热自然循环锅炉的高温爆管问题,在锅炉安装了18个壁温测点.通过对这些壁温实测数据的分析,搞清了高温过热器爆管的原因,提出了处理的意见.

  8. Discussion on Reasons of Overheating Tube Rupture of the Pendant Superheater in 670t/h Boiler%670t/h锅炉屏式过热器爆管原因分析及其解决方案

    Institute of Scientific and Technical Information of China (English)

    吴安; 李晋

    2003-01-01

    通过对T型炉屏式过热器系统的流量分配、热偏差、壁温、强度等详细计算分析,找出了该炉运行以来发生屏式过热器管子超温爆管的主要原因是,原设计屏式过热器系统连接方式不合理引起的大的流量偏差,导致少数受热强而流量小的管子超温爆管.提出了5个改进方案,从中择其一个实施之.经实测,与计算值较好吻合,验证了理论分析计算方法的可靠性.图7表5

  9. Analysis on Tube Rupture Issues of Platen Superheater in One 600 MW Supercritical Boiler%某600MW超临界锅炉屏式过热器爆管原因分析

    Institute of Scientific and Technical Information of China (English)

    徐巧生; 张辉涛

    2012-01-01

    针对某超临界600 MW锅炉屏式过热器的3次爆管问题,详细介绍了爆管发生的过程、现场设备检查结果和运行控制特征,在此基础上分析了爆管的原因,并提出了相应的爆管预防技术措施.

  10. Progress in CPI Microwave Tube Development

    Science.gov (United States)

    Wright, Edward L.; Bohlen, Heinz

    2006-01-01

    CPI continues its role as a leading supplier of state-of-the-art, high-power microwave tubes; from linear beam, velocity- and density-modulated devices, to high frequency gyro-devices. Klystrons are the device-of-choice for many high-power microwave applications, and can provide multi-megawatts to multi-kilowatts of power from UHF to W-band, respectively. A number of recent and on-going developments will be described. At UHF frequencies, the inductive output tube (IOT) has replaced the klystron for terrestrial NTSC and HDTV broadcast, due to its high efficiency and linearity, and is beginning to see use in scientific applications requiring 300 kW or less. Recent advances have enabled use well into L-band. CPI has developed a number of multiple-beam amplifiers. The VKL-8301 multiple-beam klystron (MBK) was built for the TESLA V/UV and x-ray FEL projects, and is a candidate RF source for the International Linear Collider (ILC). We have also contributed to the development of the U.S. Naval Research Laboratory (NRL) high-power fundamental-mode S-band MBK. The VHP-8330B multiple-beam, high-order mode (HOM) IOT shows great promise as a compact, CW UHF source for high power applications. These topics will be discussed, along with CPI's development capabilities for new and novel applications. Most important is our availability to provide design and fabrication services to organizations requiring CPI's manufacturing and process control infrastructure to build and test state-of-the-art devices.

  11. Osmotic regulation of seamless tube growth.

    Science.gov (United States)

    Schottenfeld-Roames, Jodi; Ghabrial, Amin S

    2013-02-01

    Most organs are composed of tubes of differing cellular architectures, including intracellular 'seamless' tubes. Two studies examining the morphogenesis of the seamless tubes formed by the excretory canal cell in Caenorhabditis elegans reveal a previously unappreciated role for osmoregulation of tubulogenesis: hyperosmotic shock recruits canalicular vesicles to the lumenal membrane to promote seamless tube growth. PMID:23377027

  12. Osmotic regulation of seamless tube growth

    OpenAIRE

    Schottenfeld-Roames, Jodi; Ghabrial, Amin S.

    2013-01-01

    Most organs are composed of tubes of differing cellular architectures, including intracellular, “seamless” tubes. Two studies examining the morphogenesis of the C. elegans excretory canal cell seamless tubes reveal a previously unappreciated role for osmoregulation of tubulogenesis: hyperosmotic shock recruits canalicular vesicles to the lumenal membrane to promote seamless tube growth.

  13. Combustion engineering: steam generator tube bending practices

    International Nuclear Information System (INIS)

    The tube bending practices and procedures employed by Combustion Engineering (CE), when bending inconel tubing is discussed. CE has two different type tube geometries in the steam generator. The innermost tubes are 1800 U-bends while the majority of the tubes have two (2) 900 bends with a straight leg between these 900 bends. The first 18 rows have U-bends (2 1/2'' to 11''R), while the remaining tubes have the double 900 geometry. All double 900 bends are bent to a 10'' radius. This presentation will address the following important parameters necessary to achieve a high quality bent tube: fabrication requirements at the tube mill; tube bending equipment; tube bending operation; inspection and final preparation; and packaging

  14. Current practices for ultrasonic and radiographic examination of tubes, tube plates and tube-plate welds of tube bundles in heat exchangers. Chapter 3

    International Nuclear Information System (INIS)

    The chapter describes the ultrasonic and radiographic inspection procedures that are applied to heat exchanger tube bundles. The inspection process starts with the ultrasonic examination of the tubes and tube plates during manufacture, followed by radiography of the tube-to-tube-plate welds during fabrication of the tube bundle. Ultrasonic methods are explained for welds which are amenable to this type of inspection. For the in-service inspection of tube bundles the chapter relates the authors' experiences on the ultrasonic inspection of tubes and tube plates in the Prototype Fast Breeder Reactor at Dounreay. At the end of the chapter some comments are made about future ultrasonic and radiographic developments for tube bundles. (author)

  15. Continuation of Studies on Development of ODS Heat Exchanger Tubing

    Energy Technology Data Exchange (ETDEWEB)

    Lawrence Brown; David Workman; Bimal Kad; Gaylord Smith; Archie Robertson; Ian Wright

    2008-04-15

    The Department of Energy (DOE), National Energy Technology Center (NETL), has initiated a strategic plan for the development of advanced technologies needed to design and build fossil fuel plants with very high efficiency and environmental performance. These plants, referred to as 'Vision 21' and FutureGen programs by DOE, will produce electricity, chemicals, fuels, or a combination of these products, and possibly secondary products such as steam/heat for industrial use. MA956 is a prime candidate material being considered for a high temperature heat exchanger in the 'Vision 21' and FutureGen programs. This material is an oxide dispersion strengthened (ODS) alloy; however, there are some gaps in the data required to commit to the use of these alloys in a full-size plant. To fill the technology gaps for commercial production and use of the material for 'Advanced Power Generation Systems' this project has performed development activity to significant increase in circumferential strength of MA956 as compared to currently available material, investigated bonding technologies for bonding tube-to-tube joints through joining development, and performed tensile, creep and fire-side corrosion tests to validate the use and fabrication processes of MA956 to heat exchanger tubing applications. Development activities within this projected has demonstrated increased circumferential strength of MA956 tubes through flow form processing. Of the six fabrication technologies for bonding tube-to-tube joints, inertia friction welding (IFW) and flash butt welding (FBW) were identified as processes for joining MA956 tubes. Tensile, creep, and fire-side corrosion test data were generated for both base metal and weld joints. The data can be used for design of future systems employing MA956. Based upon the positive development activities, two test probes were designed and fabricated for field exposure testing at 1204 C ({approx}2200 F) flue gas. The probes

  16. Effects of hunger level and tube diameter on thefeeding behavior of teat-fed dairy calves

    DEFF Research Database (Denmark)

    Herskin, Mette S; Skjøth, Flemming; Jensen, Margit Bak

    2010-01-01

    via esophageal tube before feeding; increased, in which calves were fed half milk ration at the previous feeding, or control, in which calves were fed normal ration at the previous feeding) on feeding behavior of calves fed via different tube diameters (6.0, 3.0, or 1.5 mm). Behavior observed during a...... 40-min period after morning milk feeding on d 7, 9, and 11 of testing is reported. No significant interactions between tube diameter and hunger level on behavior were found. Reduced tube diameter led to increased latency to empty the teat bucket, increased duration of nutritive sucking, and decreased...... sucking and butting when hunger was increased. The results suggest that nonnutritive sucking is a more sensitive indicator than drinking rate of changes in feeding motivation. Consequently, reduction in nonnutritive sucking might be a new candidate in the search for behavioral indicators of disease in...

  17. Development of High-Performance Pressure Tube Material for the Canadian SCWR Concept

    Science.gov (United States)

    Walters, L.; Donohue, S.

    2016-02-01

    The Canadian super-critical water-cooled reactor (SCWR) concept is moderated by using heavy water, while the coolant is light water at 25 MPa with an inlet temperature of 625 K and an outlet temperature of 900 K. The fuel assemblies reside in vertical pressure tubes that are the pressure boundary. The pressure tubes are insulated from the fuel assemblies and operate at temperatures near the moderator temperature, at 390 K. The zirconium alloy Excel has been selected as a candidate material for the pressure tube based on favorable properties such as high strength, resistance to radiation-induced diametral strain, and high terminal solid solubility. However, significant future effort will be required to obtain material properties and crack initiation mechanisms at super-critical water (SCW) conditions to verify that annealed Excel is a viable option as a pressure tube material in the Canadian SCWR.

  18. Tube feeding patients with dementia.

    Science.gov (United States)

    Chernoff, Ronni

    2006-04-01

    As the population ages, the incidence of dementia increases. All types of dementia, whether they are reversible or irreversible, lead to loss of intellectual function and judgment, memory impairment, and personality changes. The skills to feed oneself, use eating utensils, and consume items recognized as food, thereby maintaining nutrition status, may be lost as dementia progresses. Reports indicate that nutrition status may be maintained when patients are hand fed, but this is labor intensive and therefore expensive. Feeding via a percutaneous endoscopic gastrostomy tube is often chosen as an acceptable alternative. Research indicates that there is little benefit in this population when aggressive nutrition support is instituted. Providing tube feeding to patients with dementia does not necessarily extend life, increase weight, or reduce the incidence of pressure ulcers or aspiration. There are many legal and ethical issues involved in the decision to place a feeding tube in demented patients. The primary issue in patients with dementia may be autonomy and the right of an individual to decide whether or not a tube should be placed at all. Legally, there is clear precedent that the courts see the insertion of a feeding tube as extraordinary care that the patient has the right to refuse. However, much of case law is derived from cases of patients who were in a persistent vegetative state. Advance directives help to determine what the patient would want for himself. Considering all the options before the patient can no longer make decisions is the most desirable course. PMID:16556924

  19. Physics of magnetic flux tubes

    CERN Document Server

    Ryutova, Margarita

    2015-01-01

    This book is the first account of the physics of magnetic flux tubes from their fundamental properties to collective phenomena in an ensembles of flux tubes. The physics of magnetic flux tubes is absolutely vital for understanding fundamental physical processes in the solar atmosphere shaped and governed by magnetic fields. High-resolution and high cadence observations from recent space and  ground-based instruments taken simultaneously at different heights and temperatures not only show the ubiquity of filamentary structure formation but also allow to study how various events are interconnected by system of magnetic flux tubes. The book covers both theory and observations. Theoretical models presented in analytical and phenomenological forms are tailored for practical applications. These are welded with state-of-the-art observations from early decisive ones to the most recent data that open a new phase-space for exploring the Sun and sun-like stars. Concept of magnetic flux tubes is central to various magn...

  20. Analysis of autofrettaged metal tubes

    International Nuclear Information System (INIS)

    Thick-walled cylinders are widely used as compressor cylinders, pump cylinders, high pressure tubing, process reactors and vessels, nuclear reactors, isostatic vessels and gun barrels. In practice, cylinders are generally subjected to sudden and frequently drastic pressure fluctuations, such as the pressure generated in a gun barrel upon the firing of the weapon, pressure reversals in pump cylinders or in process reactors employing high-pressure piping, necessitating enhanced strength of such cylinders. A process for enhancing the strength of thick-walled cylinders has been in service, and is referred to as 'autofrettage'. It extends the service life of the cylinder. The autofrettage is achieved by increasing elastic strength of a cylinder with various methods such as hydraulic pressurization, mechanical swaging, or by utilizing the pressure of a powder gas. This research work deals with the hydraulic and mechanical autofrettage of metal tubes with the objective to attain enhanced strength. Five metal tubes are taken randomly for analysis purpose. The experimental data for five metal tubes is obtained to analyze the behavior of different parameters used during, before, and after autofrettage process. For this research, two-stage autofrettage is taken into consideration. The modeling of the metal tube is carried out in WildFire-ProEngineering, and for analysis purpose, finite element software ANSYS7 and COSMOS are used. The graphical analysis of swage autofrettage is carried out using MATLAB7. The results are validated using available experimental and numerical data. (author)

  1. A study on integrity of LMFBR secondary cooling system to hypothetical tube failure propagation in the steam generator

    International Nuclear Information System (INIS)

    -LT code also developed in ANL. In this preliminary work event trees have been prepared to make clear the scenario from the initial small-scale leak to the severest large-scale leak due to the tube failure propagation in SG. The probability of failures of leak detectors, nickel membrane-type hydrogen detectors in sodium and pressure gauges that observe the cover gas pressure of SG (EV: evaporator and SH: superheater), is considered in the event trees. On the other hand, rupture disks in SH and EV were assumed to have the normal function in leak detection and reaction products release. In some cases, water/steam blow valves to mitigate leak propagation were assumed hypothetically to fail after the plant trip, and the water and steam remained in SG are not released. A relation between the maximum leak rate resulting from the tube failure propagation and the probability of its occurrence was obtained tentatively from these considerations. Then, the effect of pressure generated by the sodium-water reaction was evaluated to the structural integrity of the secondary cooling system components. (authors)

  2. An Efficient Approach for Candidate Set Generation

    OpenAIRE

    Nawar Malhis; Arden Ruttan; Hazem H. Refai

    2005-01-01

    When Apriori was first introduced as an algorithm for discovering association rules in a database of market basket data, the problem of generating the candidate set of the large set was a bottleneck in Apriori's performance, both in space and computational requirements. At first, many unsuccessful attempts were made to improve the generation of a candidate set. Later, other algorithms that out performed Apriori were developed that generate association rules without using a candidate set. They...

  3. Cardiac evaluation of liver transplant candidates

    OpenAIRE

    Mandell, Mercedes Susan; Lindenfeld, JoAnn; Tsou, Mei-Yung; Zimmerman, Michael

    2008-01-01

    Physicians previously thought that heart disease was rare in patients with end stage liver disease. However, recent evidence shows that the prevalence of ischemic heart disease and cardiomyopathy is increased in transplant candidates compared to most other surgical candidates. Investigators estimate that up to 26% of all liver transplant candidates have at least one critical coronary artery stenosis and that at least half of these patients will die perioperatively of cardiac complications. Ca...

  4. Failure analysis of brass tubes

    Energy Technology Data Exchange (ETDEWEB)

    Lawrence, S.J.; Bodnar, R.L. [Bethlehem Steel Corp., PA (United States)

    1997-02-01

    The 1996 Jacquet Lucas Award for Excellence in Metallography was won by Samuel J. Lawrence and Richard L. Bodnar for their analysis of cracks in Admiralty brass cooling tubes, which are part of a heat exchanger in a turbogenerator that provides electricity to a manufacturing plant. A mixture of non-recirculating city and spring pit water flows through bundles of tubes to cool the oil in which they are immersed. However, a problem developed when several of the brass tubes cracked transversely, allowing cooling water to mix with the oil. This award-winning entry in the ASM/IMS competition shows how the metallographers analyzed the cracks, and what the results were.

  5. Energy dissipation in circular tube

    Directory of Open Access Journals (Sweden)

    A.D. Girgidov

    2012-01-01

    Full Text Available Energy dissipation distribution along the circular tube radius is important in solving such problems as calculation of heat transfer by the air flow through building envelope; calculation of pressure loss in spiral flows; calculation of cyclones with axial and tangential supply of dust-containing gas.Two types of one-dimensional radially axisymmetric flows in circular tube were considered: axial flow and rotation about the axis (Rankine vortex. Relying on two- and four-layer description of axial turbulent flow energy dissipation was calculated in each layer.Similar calculation for Rankine vortex with viscous sublayer at the tube surface was provided. By employing the dissipation minimum principle the boundary radius between rigid rotation and free vortex is calculated. Approximation of the velocity distribution in Rankine vortex is proposed.

  6. Drift tubes of Linac 2

    CERN Multimedia

    1977-01-01

    With the advent of the 800 MeV PS Booster in 1972, the original injector of the PS, a 50 MeV Alvarez-type proton linac, had reached its limits, in terms of intensity and stability. In 1973 one therefore decided to build a new linac (Linac 2), also with a drift-tube Alvarez structure and an energy of 50 MeV. It had a new Cockcroft-Walton preinjector with 750 keV, instead of the previous one with 500 keV. Linac 2 was put into service in 1980. The old Linac 1 was then used for the study of, and later operation with, various types of ions. This picture shows Linac 2 drift-tubes, suspended on stems coming from the top, in contrast to Linac 1, where the drift-tubes stood on stems coming from the bottom.

  7. Structural integrity evaluation method for overheating rupture of FBR steam generator tube

    International Nuclear Information System (INIS)

    This paper describes a structural integrity evaluation method for a SG tube of FBR in case of sodium-water reaction and creep rupture tests to obtain the strength of the tube material. In the SG of FBR, if intermediate size of water/steam leak (1-2 kg s-1) would occur from a tube, it could cause overheating rupture of the multiple tubes surrounding the initially failed tube due to generated sodium-water reaction heat. In the ultra-high temperature condition, the creep strength of the material is one of the dominant factors for failure behavior. Accordingly, we tried to apply the creep failure criterion for the overheating rupture of the SG tube. The creep rupture tests have been performed at ultra-high temperature conditions ranging from 1223.2 to 1323.2 K. The test material is 'Mod.9Cr-1Mo steel' which is one of the candidate materials for the tubes of the future SG of FBR. The test results have shown that tube rupture depends on the creep strength of the material; hence, instantaneous rupture does not occur even if the stress exceeds the design value of ultimate tensile strength. The test data have been suitably expressed using the Larson-Miller Parameter, and a structural integrity evaluation method based on the sum of the use-fraction associated with the creep damage has been proposed. Based on this method, the structural integrity of the tube in the sodium-water reaction flame has been evaluated. The results show that it is important to detect the initial leak of the tube within a short period and to reduce the steam pressure more rapidly by SG blowdown

  8. Working session 3: Tubing integrity

    International Nuclear Information System (INIS)

    Twenty-three individuals representing nine countries (Belgium, Canada, the Czech Republic, France, Japan, the Slovak Republic, Spain, the UK, and the US) participated in the session on tube integrity. These individuals represented utilities, vendors, consultants and regulatory authorities. The major subjects discussed by the group included overall objectives of managing steam generator tube degradation, necessary elements of a steam generator degradation management program, the concept of degradation specific management, structural integrity evaluations, leakage evaluations, and specific degradation mechanisms. The group's discussions on these subjects, including conclusions and recommendations, are summarized in this article

  9. Flow Deflection in Intersected Tubes

    Institute of Scientific and Technical Information of China (English)

    2000-01-01

    In order to verify the flow interference at the fracture intersections, a group of hydraulic simulations of crossing flow was carried out. The manifold interference effects at the intersection of fractures on water flow has been confirmed extensively either in the normal or in the oblique intersected tubes as well as in the intersected tubes of either equal or variant diameters. Consequently, suggest that the fissure network can no longer be taken as a set of solitary fractures, but as a set of elementary intersected ractures. The deflection effect at fracture intersections on the water flow should be taken into considwhen is dealt with any theory related to the water migration in fractures.

  10. Working session 3: Tubing integrity

    Energy Technology Data Exchange (ETDEWEB)

    Cueto-Felgueroso, C. [Tecnatom, S.A., San Sebastian de los Reyes, Madrid (Spain); Strosnider, J. [NRC, Washington, DC (United States)

    1997-02-01

    Twenty-three individuals representing nine countries (Belgium, Canada, the Czech Republic, France, Japan, the Slovak Republic, Spain, the UK, and the US) participated in the session on tube integrity. These individuals represented utilities, vendors, consultants and regulatory authorities. The major subjects discussed by the group included overall objectives of managing steam generator tube degradation, necessary elements of a steam generator degradation management program, the concept of degradation specific management, structural integrity evaluations, leakage evaluations, and specific degradation mechanisms. The group`s discussions on these subjects, including conclusions and recommendations, are summarized in this article.

  11. Fluidelastic instability in tube arrays

    International Nuclear Information System (INIS)

    When an array of tubes is subjected to crossflow, the tubes can experience dynamic instability, generally called fluidelastic instability. Instability initiates when the crossflow velocity exceeds a threshold value above which energy input from the flow exceeds that dissipated by system damping. Catastrophic failures of reactor and process plant equipment have been attributed to fluidelastic instability. As a result, extensive research studies have been conducted in the last 15 years with the objective of understanding the instability mechanisms and developing general design guidelines to avoid instability. Argonne National Laboratory has a continuing research program in this area which includes both mathematical model development and experimentation. This paper describes recent developments and accomplishments

  12. On the welded Tube map

    OpenAIRE

    Audoux, Benjamin

    2014-01-01

    This note investigates the so-called Tube map which connects welded knots, that is a quotient of the virtual knot theory, to ribbon torus-knots, that is a restricted notion of fillable knotted tori in the 4-sphere. It emphasizes the fact that ribbon torus-knots with a given filling are in one-to-one correspondence with welded knots before quotient under classical Reidemeister moves and reformulates these moves and the known sources of non-injectivity of the Tube map in terms of filling changes.

  13. Mechanical Instabilities of Biological Tubes

    Science.gov (United States)

    Hannezo, Edouard; Prost, Jacques; Joanny, Jean-François

    2012-07-01

    We study theoretically the morphologies of biological tubes affected by various pathologies. When epithelial cells grow, the negative tension produced by their division provokes a buckling instability. Several shapes are investigated: varicose, dilated, sinuous, or sausagelike. They are all found in pathologies of tracheal, renal tubes, or arteries. The final shape depends crucially on the mechanical parameters of the tissues: Young’s modulus, wall-to-lumen ratio, homeostatic pressure. We argue that since tissues must be in quasistatic mechanical equilibrium, abnormal shapes convey information as to what causes the pathology. We calculate a phase diagram of tubular instabilities which could be a helpful guide for investigating the underlying genetic regulation.

  14. Nickel-chromium plasma spray coatings: A way to enhance degradation resistance of boiler tube steels in boiler environment

    Science.gov (United States)

    Sidhu, Buta Singh; Prakash, S.

    2006-03-01

    Boiler tube steels, namely low carbon steel ASTM-SA-210-Grades A1 (GrA1), 1Cr-0.5Mo steel ASTM-SA213-T-11 (T11), and 2.25Cr-1 Mo steel ASTM-SA213-T-22(T22), were used as substrate steels. Ni-22Cr-10Al-1Y powder was sprayed as a bond coat 150 μm thick before a 200 μm final coating of Ni-20Cr was applied Coatings were characterized prior to testing in the environment of a coal fire boiler. The uncoated and coated steels were inserted in the platen superheater zone of a coal fired boiler at around 755°C for 10 cycles, each 100 h. Coated steels showed lower degradation (erosion-corrosion) rate than uncoated steels showed. The lowest rate was observed in the case of Ni-20Cr coated T11 steel. Among the uncoated steels, the observed rate of degradation was the lowest for the T22 steel.

  15. Pump element for a tube pump

    DEFF Research Database (Denmark)

    2011-01-01

    The invention relates to a tube pump comprising a tube and a pump element inserted in the tube, where the pump element comprises a rod element and a first and a second non-return valve member positioned a distance apart on the rod element. The valve members are oriented in the same direction...... portion acts to alternately close and open the valve members thereby generating a fluid flow through the tube. The invention further relates to a pump element comprising at least two non-return valve members connected by a rod element, and for insertion in an at least partly flexible tube in such tube...... pump as mentioned above, thereby acting to generate a fluid flow through the tube upon repeated deformation of the tube between the two valve members. The pump element may comprise a connecting part for coupling to another tube and may comprise a sealing part establishing a fluid tight connection to a...

  16. Special Education Teacher Candidate Assessment: A Review

    Science.gov (United States)

    McCall, Zach; McHatton, Patricia Alvarez; Shealey, Monika Williams

    2014-01-01

    Teacher preparation has been under intense scrutiny in recent years. In order for preparation of special education teacher candidates to remain viable, candidate assessment practices must apply practices identified in the extant literature base, while special education teacher education researchers must extend this base with rigorous efforts to…

  17. Do People 'Like' Candidates on Facebook?

    DEFF Research Database (Denmark)

    Nielsen, Rasmus Kleis

    The online popularity of a few exceptional candidates has led many to suggest that social media have given politicians powerful ways of communicating directly with voters. In this paper, we examine whether this is happening on a significant scale and show, based on analysis of 224 candidates invo...

  18. Hot tube atomic absorption spectrochemistry.

    Science.gov (United States)

    Woodriff, R; Stone, R W

    1968-07-01

    A small, commercially available atomic absorption instrument is used with a heated graphite tube for the atomic absorption analysis of liquid and solid silver samples. Operating conditions of the furnace are described and a sensitivity of about 5 ng of silver is reported. PMID:20068797

  19. Kundt's Tube Experiment Using Smartphones

    Science.gov (United States)

    Parolin, Sara Orsola; Pezzi, Giovanni

    2015-01-01

    This article deals with a modern version of Kundt's tube experiment. Using economic instruments and a couple of smartphones, it is possible to "see" nodes and antinodes of standing acoustic waves in a column of vibrating air and to measure the speed of sound.

  20. OurTube / David Talbot

    Index Scriptorium Estoniae

    Talbot, David

    2009-01-01

    USA California Ülikooli töötajate Abram Stern'i ja Michael Dale'i poolt 2005. a. algatatud USA kongressis peetud kõnede videoremiksidest ja nende poolt loodud veebisaidist Metavid.org. Ka YouTube keskkonnast ja wikipedia katsetustest muuta oma keskkond multimeedialisemaks

  1. Working session 1: Tubing degradation

    Energy Technology Data Exchange (ETDEWEB)

    Kharshafdjian, G. [Atomic Energy of Canada, Mississauga, Ontario (Canada); Turluer, G. [IPSN, Fontenay-aux-Roses (France)

    1997-02-01

    A general introductory overview of the purpose of the group and the general subject area of SG tubing degradation was given by the facilitator. The purpose of the session was described as to {open_quotes}develop conclusions and proposals on regulatory and technical needs required to deal with the issues of SG tubing degradation.{close_quotes} Types, locations and characteristics of tubing degradation in steam generators were briefly reviewed. The well-known synergistic effects of materials, environment, and stress and strain/strain rate, subsequently referred to by the acronym {open_quotes}MESS{close_quotes} by some of the group members, were noted. The element of time (i.e., evolution of these variables with time) was emphasized. It was also suggested that the group might want to consider the related topics of inspection capabilities, operational variables, degradation remedies, and validity of test data, and some background information in these areas was provided. The presentation given by Peter Millet during the Plenary Session was reviewed; Specifically, the chemical aspects and the degradation from the secondary side of the steam generator were noted. The main issues discussed during the October 1995 EPRI meeting on secondary side corrosion were reported, and a listing of the potential SG tube degradations was provided and discussed.

  2. Oscillatory flow in bifurcating tubes

    International Nuclear Information System (INIS)

    Respiratory fluid mechanics is characterized by flow through bifurcating, Y-shaped, tubes. Steady flow through such geometries has been studied in detail by several authors. However, the recent widespread use of high frequency mechanical assistance of ventilation has generated interest in unsteady flows. A symmetric, singly branching pipe has been constructed, with its bifurcation shaped to model pulmonary conditions. The form of the bifurcation is based on CAT scans of human tracheal carinas. Its features include an area change of the parent tube from circular to roughly elliptical near the junction, a pinch-off effect on the parent tube, smoothly curved outer walls at the junction, and a sharp flow divider. Parent and daughter tubes have an l/d ratio of > 50, so that entrance effects are avoided. In order to better understand the effects of unsteadiness, piston driven, laminar, purely oscillatory flow has been established in the pipe for a variety of Womersley numbers. By appropriate choices of flow frequency and amplitude, fluid viscosity, and pipe diameter, tracheal Reynolds and Womersley numbers have been matched for resting breathing (tidal volume of 600 ml to 0.25 Hz), high frequency breathing (50 ml at 5 Hz), and intermediate breathing levels

  3. Mechanical support for straw tubes

    International Nuclear Information System (INIS)

    A design is proposed for mounting a large number of straw tubes to form an SSC central tracking chamber. The assembly is precise and of very low mass. The fabrication is modular and can be carried out with a minimum of tooling and instrumentation. Testing of modules is possible prior to the final assembly. 4 figs

  4. NEI You Tube Videos: Amblyopia

    Medline Plus

    Full Text Available ... Supported by the NEI Research at NEI All Research at NEI Office of the Scientific Director Office of the Clinical Director Education Programs ... Health Information News and Events Grants and Funding Research at NEI Education ... NEI YouTube Videos: Amblyopia NEI ...

  5. X-ray tube arrangement

    International Nuclear Information System (INIS)

    An x-ray tube is described incorporating an elongated target/ anode over which the electron beam is deflected and from which x-rays are emitted. Improved methods of monitoring and controlling the amplitude of the beam deflection are presented. (U.K.)

  6. Resonance tube or lax vox?

    Czech Academy of Sciences Publication Activity Database

    Tyrmi, J.; Radolf, Vojtěch; Horáček, Jaromír; Laukkanen, A. M.

    Firenze: Firenze University Press, 2015 - (Manfredi, C.). s. 195-195 ISBN 978-88-6655-794-4. [Pan European Voice Conference : PEVOC /11./. 31.08.2015-02.09.2015, Firenze] R&D Projects: GA ČR(CZ) GAP101/12/1306 Institutional support: RVO:61388998 Keywords : phonation into tube * voice therapy * flow resistance * contact quotient Subject RIV: BI - Acoustics

  7. Welding the CNGS decay tube

    CERN Document Server

    Maximilien Brice

    2004-01-01

    3.6 km of welds were required for the 1 km long CERN Neutrinos to Gran Sasso (CNGS) decay tube, in which particles produced in the collision with a proton and a graphite target will decay into muons and muon neutrinos. Four highly skilled welders performed this delicate task.

  8. NEI You Tube Videos: Amblyopia

    Medline Plus

    Full Text Available ... Macular Degeneration Amblyopia Animations Blindness Cataract Convergence Insufficiency Diabetic Eye Disease Dilated Eye Exam Dry Eye For Kids Glaucoma Healthy Vision Tips Leber Congenital Amaurosis Low Vision Refractive Errors Retinopathy of Prematurity Science Spanish Videos Webinars NEI YouTube ...

  9. Rejection index for pressure tubes

    International Nuclear Information System (INIS)

    The objective of the present study was to establish a set of criteria (or Rejection Index) which could be used to decide whether a zirconium-2 1/2 w/o niobium pressure tube in a CANDU reactor should be removed from service due to in-service degradation. A critique of key issues associated with establishing a realistic rejection index was prepared. Areas of uncertainty in available information were identified and recommendations for further analysis and laboratory testing made. A Rejection Index based on the following limits has been recommended: 1) Limits related to design intent and normal operation: any garter spring must remain within the tolerance band specified for its design location; the annulus gas system must normally be operated in a circulating mode with a procedure in place for purging to prevent accumulation of deuterium. It must remain sensitive to leaks into any part of the systems; and pressure tube dimensions and distortions must be limited to maintain the fuel channels within the original design intent; 2) Limits related to defect tolerance: adequate time margins between occurrence of a leaking crack and unstable failure must be demonstrated for all fuel channels; long lap-type flaws are unacceptable; crack-like defects of any size are unacceptable; and score marks, frat marks and other defects with contoured profiles must fall below certain depth, length and stress intensity limits; and 3) Limits related to property degradation: at operating temperature each pressure tube must be demonstrated to have a critical length in excess of a stipulated value; the maximum equivalent hydrogen level in any pressure tube should not exceed a limit which should be defined taking into account the known history of that tube; the maximum equivalent hydrogen level in any rolled joint should not exceed a limit which is presently recommended as 200 ppm equivalent hydrogen; and the maximum diametral creep strain should be limited to less than 5%

  10. Bulk metallic glass tube casting

    International Nuclear Information System (INIS)

    Research highlights: → Tubular specimens of Zr55Cu30Al10Ni5 cast in custom arc-melting furnace. → Tilt casting supplemented by suction casting. → Bulk metallic glass formed only with optimized processing parameters. → Fully amorphous tubes with 1.8 mm wall thickness and 25 mm diameter. - Abstract: Tubular bulk metallic glass specimens were produced, using a custom-built combined arc-melting tilt-casting furnace. Zr55Cu30Al10Ni5 tubes with outer diameter of 25 mm and 0.8-3 mm wall thicknesses were cast, with both tilt and suction casting to ensure mold filling. Tilt casting was found to fill one side of the tube mold first, with the rest of the tube circumference filled subsequently by suction casting. Optimized casting parameters were required to fully fill the mold and ensure glass formation. Too small melt mass and too low arc power filled the mold only partially. However, too large melt mass and higher arc power which lead to the best mold filling also lead to partial crystallization. Variations in processing parameters were explored, until a glassy ring with 1.8 mm thickness was produced. Different sections of the as-cast ring were investigated by X-ray diffraction (XRD), differential scanning calorimetry (DSC), and instrumented indentation to ensure amorphous microstructure. Atomic force microscopy (AFM) was used to compare the surface qualities of the first- and last-filled sections. These measurements confirmed the glassy structure of the cast ring, and that, the tilt cast tube section consistently showed better surface quality than the suction cast section. Optimized casting parameters are required to fully realize the potential of directly manufacturing complex shapes out of high-purity bulk metallic glasses by tilt casting.

  11. Novel Photo Multiplier Tubes for the Cherenkov Telescope Array Project

    CERN Document Server

    Toyama, Takeshi; Dickinson, Hugh; Fruck, Christian; Hose, Jürgen; Kellermann, Hanna; Knötig, Max; Lorenz, Eckart; Menzel, Uta; Nakajima, Daisuke; Orito, Reiko; Paneque, David; Schweizer, Thomas; Teshima, Masahiro; Yamamoto, Tokonatsu

    2013-01-01

    Currently the standard light sensors for imaging atmospheric Cherenkov telescopes are the classical photo multiplier tubes that are using bialkali photo cathodes. About eight years ago we initiated an improvement program with the Photo Multiplier Tube (PMT) manufacturers Hamamatsu (Japan), Electron Tubes Enterprises (England) and Photonis (France) for the needs of imaging atmospheric Cherenkov telescopes. As a result, after about 40 years of stagnation of the peak Quantum Efficiency (QE) on the level of 25-27%, new PMTs appeared with a peak QE of 35%. These have got the name super-bialkali. The second significant upgrade has happened very recently, as a result of a dedicated improvement program for the candidate PMT for Cherenkov Telescope Array. The latter is going to be the next generation major instrument in the field of very high energy gamma astrophysics and will consist of over 100 telescopes of three different sizes of 23m, 12m and 4-7m, located both in southern and northern hemispheres. Now PMTs with ...

  12. The accessory fallopian tube: A rare anomaly

    Directory of Open Access Journals (Sweden)

    Kusum R Gandhi

    2012-01-01

    Full Text Available This paper presents a rare anatomical variation in the form of accessory fallopian tube on right side. The duplication of fallopian tube was observed in a 34-year-old female during routine undergraduate dissection in our department. Fallopian tube is the part of uterus that carries the ovum from the ovary to the uterus. Accessory fallopian tube is the congenital anomaly attached to the ampullary part of main tube. This accessory tube is common site of pyosalpinx, hydrosalpinx, cystic swelling and torsion. The ovum released by the ovary may also be captured by the blind accessory tube leading to infertility or ectopic pregnancy. Hence, all patients of infertility or pelvic inflammatory disease should be screened to rule out the presence of accessory fallopian tube and if encountered should be removed.

  13. Physics of particles in the rotating tube

    OpenAIRE

    Pardy, Miroslav

    2011-01-01

    The classical and the quantum motion of a massive body in the rotating tube is considered. Photon is included. The spin motion described by the Bargmann-Michel-Telegdi equation is considered in the rotation tube and rotating system.

  14. Chemical cleaning specification: few tube test model

    International Nuclear Information System (INIS)

    The specification is for the waterside chemical cleaning of the 2 1/4 Cr - 1 Mo steel steam generator tubes. It describes the reagents and conditions for post-chemical cleaning passivation of the evaporator tubes

  15. When to change a tracheostomy tube.

    Science.gov (United States)

    White, Alexander C; Kher, Sucharita; O'Connor, Heidi H

    2010-08-01

    Knowing when to change a tracheostomy tube is important for optimal management of all patients with tracheostomy tubes. The first tracheostomy tube change, performed 1-2 weeks after placement, carries some risk and should be performed by a skilled operator in a safe environment. The risk associated with changing the tracheostomy tube then usually diminishes over time as the tracheo-cutaneous tract matures. A malpositioned tube can be a source of patient distress and patient-ventilator asynchrony, and is important to recognize and correct. Airway endoscopy can be helpful to ensure optimal positioning of a replacement tracheostomy tube. Some of the specialized tracheostomy tubes available on the market are discussed. There are few data available to guide the timing of routine tracheostomy tube changes. Some guidelines are suggested. PMID:20667154

  16. Method of tube plate outlet replacement

    International Nuclear Information System (INIS)

    Leaking or defective welded joints of tube plate outlets encountered during nuclear installation operation must be repaired. A method is suggested in which the defective tube plate outlets are first sealed below the cutting site to protect the tube plate from the penetration of dirt and then cut off. The remaining part of the tubes is cleaned. Extension tubes are then welded using argon arc electrode welding. They are shortened to required lengths and the cleaned tube plate is removed. The tube ends shall be calibration rolled and welded manually in two passes with a non-melting electrode using argon arc welding, the first pass without, the second pass with a filler wire. The ends of the tubes shall then be closed by rolling, leak tests shall be conducted and the plugs removed. (M.D.)

  17. Dynamics Calculation of Travel Wave Tube

    Institute of Scientific and Technical Information of China (English)

    2011-01-01

    During the dynamics calculating of the travel tube, we must obtain the field map in the tube. The field map can be affected by not only the beam loading, but also the attenuation coefficient. The calculation of the attenuation coefficient

  18. Ultrasonic testing of steam generator tubes

    International Nuclear Information System (INIS)

    A system is developed for inspection of steam generator tube, especially near the tube plate. Imaging, thickness measurement, radial profilometry, longitudinal and circonferential crack detection and welded joints testing are reviewed

  19. Tube Thoracostomy: Complications and Its Management

    OpenAIRE

    Chinenye Kesieme; Eshiobo Irekpita; Nze Jebbin; Ndubueze Ezemba; Andrew Dongo; Kesieme, Emeka B.

    2011-01-01

    Background. Tube thoracostomy is widely used throughout the medical, surgical, and critical care specialities. It is generally used to drain pleural collections either as elective or emergency. Complications resulting from tube thoracostomy can occasionally be life threatening. Aim. To present an update on the complications and management of complications of tube thoracostomy. Methods. A review of the publications obtained from Medline search, medical libraries, and Google on tube thoracostom...

  20. Tube morphogenesis: closure, but many openings remain

    OpenAIRE

    Nelson, W. James

    2003-01-01

    Epithelial and endothelial tubes form the basic structure of many organs and tissues in the fruit fly Drosophila melanogaster, the nematode Caenorhabditis elegans, zebrafish and mammals. Comparison of how tubes form during development defines several pathways that generate a single unbranched tube or dichotomously branching tubular networks. The formation of tubes can be induced directly by intrinsic signals within epithelial primordia or by inductive signaling between adjacent epithelia and ...

  1. Ceramic vacuum tubes for geothermal well logging

    Energy Technology Data Exchange (ETDEWEB)

    Kelly, R.D.

    1977-01-01

    Useful design data acquired in the evaluation of ceramic vacuum tubes for the development of a 500/sup 0/C instrumentation amplifier are presented. The general requirements for ceramic vacuum tubes are discussed for application to the development of high temperature well logs. Commercially available tubes are described and future contract activities that specifically relate to ceramic vacuum tubes are detailed. Supplemental data are presented in the appendix.

  2. Burnout experiments on the externally-finned swirl tube for steady-state and high-heat flux beam stops

    International Nuclear Information System (INIS)

    An experimental study to develop beam stops for the next generation of neutral beam injectors was started, using an ion source developed for the JT-60 neutral beam injector. A swirl tube is one of the most promising candidates for a beam stop element which can handle steady-state and high-heat flux beams. In the present experiments, a modified swirl tube, namely an externally-finned swirl tube, was tested together with a simple smooth tube, an externally finned tube, and an internally finned tube. The major dimensions of the tubes are 10 mm in outer-diameter, 1.5 mm in wall thickness, 15 mm in external fin width, and 700 mm in length. The burnout heat flux (CHF) normal to the externally finned swirl tube was 4.1±0.1 kW/cm2, where the Gaussian e-folding half-width of the beam intensity distribution was about 90 mm, the flow rate of the cooling water was 30 l/min, inlet and outlet gauge pressures were about 1 MPa and 0.2 MPa, respectively, and the temperature of the inlet water was kept to 200C during a pulse. A burnout heat flux ratio, which is defined by the ratio of the CHF value of the externally-finned swirl tube to that of the externally-finned tube, turned out to be about 1.5. Burnout heat fluxes of the tubes with a swirl tape or internal fins increase linearly with an increase of the flow rate. It was found that the tube with external fins has effects that not only reduce the thermal stress but also improve the characteristics of boiling heat transfer. (orig.)

  3. The Fuge Tube Diode Array Spectrophotometer

    Science.gov (United States)

    Arneson, B. T.; Long, S. R.; Stewart, K. K.; Lagowski, J. J.

    2008-01-01

    We present the details for adapting a diode array UV-vis spectrophotometer to incorporate the use of polypropylene microcentrifuge tubes--fuge tubes--as cuvettes. Optical data are presented validating that the polyethylene fuge tubes are equivalent to the standard square cross section polystyrene or glass cuvettes generally used in…

  4. Welding device inside a small diameter tube

    International Nuclear Information System (INIS)

    The orbital welding tool is supported in a socket at the end of a flexible tube. A motor rotating the head is placed in a casing fixed to the other end of the flexible tube and rotates the welding tool by the intermediary of a flexible transmission. A second flexible tube fixed to the casing permits the translation of the welding tool

  5. Inclusive spectra of hadrons created by color tube fission 1. Probability of tube fission

    OpenAIRE

    Gedalin, E. V.

    1997-01-01

    The probability of color tube fission that includes the tube surface small oscillation corrections is obtained with pre-exponential factor accuracy on the basis of previously constructed color tube model. Using these expressions the probability of the tube fission in $n$ point is obtained that is the basis for calculation of inclusive spectra of produced hadrons.

  6. Control rod guide tube assembly

    International Nuclear Information System (INIS)

    An improved fuel assembly is described as consisting of a sleeve that engages one end of a control rod guide tube essentially fixing the guide tube to one of the fuel assembly end structures. The end of the sleeve protrudes above the surface of the end fitting. The outer surface of the sleeve has a peripheral groove that engages the resilient sides of a cellular grid or lattice shaped lock. This lock fixes the sleeve in position between the various elements that comprise the end fitting, thereby eliminating a profusion of costly and potentially troublesome nuts, threaded studs and the like that are frequently employed in the fuel assemblies that are presently in use

  7. Microstructural degradation in compound tubes

    Energy Technology Data Exchange (ETDEWEB)

    Salonen, J.; Auerkari, P. [VTT Manufacturing Technology, Espoo (Finland)

    1996-12-31

    In order to quantify microstructural degradation at high temperatures, samples of SA 210 / AISI 304 L compound tube material were annealed in the temperature range 540-720 deg C for 1 to 1 000 hours. The hardness of the annealed material was measured and the micro structure of the samples was investigated with optical and scanning electron microscopy. Microstructural degradation was characterised by the carbide structure in the ferritic-pearlitic base material and by the depth of decarburised and carburised zones of the compound tube interface. The observed changes were quantified in terms of their time and temperature dependence and diffusion coefficients of the process. The results can be used in estimating the extent of thermal exposure of high-temperature components after long-term service or after incidences of overheating. (orig.) (4 refs.)

  8. HIGH CURRENT COAXIAL PHOTOMULTIPLIER TUBE

    Science.gov (United States)

    Glass, N.W.

    1960-01-19

    A medium-gain photomultiplier tube having high current output, fast rise- time, and matched output impedance was developed. The photomultiplier tube comprises an elongated cylindrical envelope, a cylindrical anode supported at the axis of the envelope, a plurality of elongated spaced opaque areas on the envelope, and a plurality of light admitting windows. A photo-cathode is supported adjacent to each of the windows, and a plurality of secondary emissive dynodes are arranged in two types of radial arrays which are alternately positioned to fill the annular space between the anode and the envelope. The dynodes are in an array being radially staggered with respect to the dynodes in the adjacent array, the dynodes each having a portion arranged at an angle with respect to the electron path, such that electrons emitted by each cathode undergo multiplication upon impingement on a dynode and redirected flight to the next adjacent dynode.

  9. Ionization tube simmer current circuit

    Science.gov (United States)

    Steinkraus, Jr., Robert F.

    1994-01-01

    A highly efficient flash lamp simmer current circuit utilizes a fifty percent duty cycle square wave pulse generator to pass a current over a current limiting inductor to a full wave rectifier. The DC output of the rectifier is then passed over a voltage smoothing capacitor through a reverse current blocking diode to a flash lamp tube to sustain ionization in the tube between discharges via a small simmer current. An alternate embodiment of the circuit combines the pulse generator and inductor in the form of an FET off line square wave generator with an impedance limited step up output transformer which is then applied to the full wave rectifier as before to yield a similar simmer current.

  10. Scintillation counter: photomultiplier tube alignment

    International Nuclear Information System (INIS)

    A scintillation counter, particularly for counting gamma ray photons, includes a massive lead radiation shield surrounding a sample-receiving zone. The shield is disassembleable into a plurality of segments to allow facile installation and removal of a photomultiplier tube assembly, the segments being so constructed as to prevent straight-line access of external radiation through the shield into the sample receiving zone. Provisions are made for accurately aligning the photomultiplier tube with respect to one or more sample-transmitting bores extending through the shield to the sample receiving zone. A sample elevator, used in transporting samples into the zone, is designed to provide a maximum gamma-receiving aspect to maximize the gamma detecting efficiency. (auth)

  11. Origami interleaved tube cellular materials

    International Nuclear Information System (INIS)

    A novel origami cellular material based on a deployable cellular origami structure is described. The structure is bi-directionally flat-foldable in two orthogonal (x and y) directions and is relatively stiff in the third orthogonal (z) direction. While such mechanical orthotropicity is well known in cellular materials with extruded two dimensional geometry, the interleaved tube geometry presented here consists of two orthogonal axes of interleaved tubes with high interfacial surface area and relative volume that changes with fold-state. In addition, the foldability still allows for fabrication by a flat lamination process, similar to methods used for conventional expanded two dimensional cellular materials. This article presents the geometric characteristics of the structure together with corresponding kinematic and mechanical modeling, explaining the orthotropic elastic behavior of the structure with classical dimensional scaling analysis. (paper)

  12. Mechanical Instabilities of Biological Tubes

    CERN Document Server

    Hannezo, Edouard; Prost, Jacques; 10.1103/PhysRevLett.109.018101

    2012-01-01

    We study theoretically the shapes of biological tubes affected by various pathologies. When epithelial cells grow at an uncontrolled rate, the negative tension produced by their division provokes a buckling instability. Several shapes are investigated : varicose, enlarged, sinusoidal or sausage-like, all of which are found in pathologies of tracheal, renal tubes or arteries. The final shape depends crucially on the mechanical parameters of the tissues : Young modulus, wall-to-lumen ratio, homeostatic pressure. We argue that since tissues must be in quasistatic mechanical equilibrium, abnormal shapes convey information as to what causes the pathology. We calculate a phase diagram of tubular instabilities which could be a helpful guide for investigating the underlying genetic regulation.

  13. The comparison of corrosion resistance between Baosteel's alloy 690 tube and foreign alloy 690 tube

    International Nuclear Information System (INIS)

    Alloy 690 having excellent corrosion resistance is widely used for SG tubes. The intergranular corrosion and pitting corrosion resistance of Baosteel's alloy 690 tube, Country A alloy 690 tube and Country B alloy 690 tube have been analysed by comparison. It shows that: The intergranular corrosion of Baosteel's alloy 690 tube tested complied with ASTM G28 Standard could satisfy the technical requirement. However.some of Baosteel's alloy 690 tube in intergranular corrosion resistance had less performance than Country A. In addition, pitting corrosion tested with ASTM G48 Standard shown the Baosteel's alloy 690 tube better than Country B. (authors)

  14. Fields in multilayer beam tubes

    International Nuclear Information System (INIS)

    Equations are presented for calculating the fields from a bunched beam that penetrate into the layers of a beam tube of circular cross section. Starting from the radial wave impedance of an outer surface, the wave functions in inner layers are calculated numerically to obtain field strengths or the longitudinal beam impedance. Examples of a vertex-detector region and of an injection kicker are given

  15. Flux tubes at Finite Temperature

    CERN Document Server

    Bicudo, Pedro; Cardoso, Marco

    2016-01-01

    We show the flux tubes produced by static quark-antiquark, quark-quark and quark-gluon charges at finite temperature. The sources are placed in the lattice with fundamental and adjoint Polyakov loops. We compute the square densities of the chromomagnetic and chromoelectric fields above and below the phase transition. Our results are gauge invariant and produced in pure gauge SU(3). The codes are written in CUDA and the computations are performed with GPUs.

  16. Cattle Candidate Genes for Milk Production Traits

    OpenAIRE

    Kadlec,Tomáš

    2012-01-01

    The aim of this thesis is to make an overview of important candidate genes affecting milk yield and milk quality parameters, with an emphasis on genes associated with the quantity and quality of milk proteins and milk fat.

  17. Evaluating historical candidate genes for schizophrenia

    DEFF Research Database (Denmark)

    Farrell, M S; Werge, T; Sklar, P;

    2015-01-01

    Prior to the genome-wide association era, candidate gene studies were a major approach in schizophrenia genetics. In this invited review, we consider the current status of 25 historical candidate genes for schizophrenia (for example, COMT, DISC1, DTNBP1 and NRG1). The initial study for 24 of these...... genes explicitly evaluated common variant hypotheses about schizophrenia. Our evaluation included a meta-analysis of the candidate gene literature, incorporation of the results of the largest genomic study yet published for schizophrenia, ratings from informed researchers who have published on these...... genes, and ratings from 24 schizophrenia geneticists. On the basis of current empirical evidence and mostly consensual assessments of informed opinion, it appears that the historical candidate gene literature did not yield clear insights into the genetic basis of schizophrenia. A likely reason why...

  18. Scattering Properties of Candidate Planetary Regolith Materials

    Science.gov (United States)

    Nelson, R. M.; Smythe, W. D.; Hapke, B. W.; Hale, A. S.; Piatek, J. A.

    2001-01-01

    The laboratory investigation of the scattering properties of candidate planetary regolith materials is an important technique for understanding the physical properties of a planetary regolith. Additional information is contained in the original extended abstract.

  19. Characterization of nanoparticles as candidate reference materials

    International Nuclear Information System (INIS)

    We report the characterization of three different nanoparticles (silica, silver and multi-walled carbon nanotubes) as candidate reference material. We focus our analysis on the size distribution of those particles as measured by different microscopy techniques. (author)

  20. Characterization of nanoparticles as candidate reference materials

    Energy Technology Data Exchange (ETDEWEB)

    Martins Ferreira, E.H.; Robertis, E. de; Landi, S.M.; Gouvea, C.P.; Archanjo, B.S.; Almeida, C.A.; Araujo, J.R. de; Kuznetsov, O.; Achete, C.A., E-mail: smlandi@inmetro.gov.br [Instituto Nacional de Metrologia, Qualidade e Tecnologia (INMETRO), Rio de Janeiro, RJ (Brazil)

    2013-07-01

    We report the characterization of three different nanoparticles (silica, silver and multi-walled carbon nanotubes) as candidate reference material. We focus our analysis on the size distribution of those particles as measured by different microscopy techniques. (author)

  1. 76 FR 4896 - Call for Candidates

    Science.gov (United States)

    2011-01-27

    ... accepted accounting principles for federal government entities. Generally, non-federal Board members are... From the Federal Register Online via the Government Publishing Office FEDERAL ACCOUNTING STANDARDS ADVISORY BOARD Call for Candidates AGENCY: Federal Accounting Standards Advisory Board. ACTION:...

  2. 76 FR 36130 - Call for Candidates

    Science.gov (United States)

    2011-06-21

    ... establish generally accepted accounting principles for federal government entities. Generally, non- federal... From the Federal Register Online via the Government Publishing Office FEDERAL ACCOUNTING STANDARDS ADVISORY BOARD Call for Candidates AGENCY: Federal Accounting Standards Advisory Board. ACTION: Request...

  3. Dynamic characteristics of heat exchanger tubes vibrating in a tube support plate inactive mode

    International Nuclear Information System (INIS)

    Tubes in shell-and-tube heat exchangers, including nuclear plant steam generators, derive their support from longitudinally positioned tube support plates (TSPs). Typically there is a clearance between the tube and TSP hole. Depending on design and fabrication tolerances, the tube may or may not contact all of the TSPs. Noncontact results in an inactive TSP which can lead to detrimental flow induced tube vibrations under certain conditions dependent on the resulting tube-TSP interaction dynamics and the fluid excitation forces. The purpose of this study is to investigate the tube-TSP interaction dynamics. Results of an experimental study of damping and natural frequency as functions of tube-TSP diametral clearance and TSP thickness are reported. Calculated values of damping ratio and frequency of a tube vibrating within an inactive TSP are also presented together with a comparison of calculated and experimetnal quantities

  4. Ultrasonic inspection of inpile tubes

    International Nuclear Information System (INIS)

    The in-service inspection (ISI) of inpile tubes can be performed accurately and safely with a semiautomatic ultrasonic inspection system. The ultrasonic technique uses a set of multiple transducers to detect and size cracks, voids, and laminations radially and circumferentially. Welds are also inspected for defects. The system is designed to inspect stainless steel and Inconel tubes ranging from 53.8 mm (2.12 in.) to 101.6 mm (4 in.) inner diameter with wall thickness on the order of 5 mm. The inspection head contains seven transducers mounted in a surface-following device. Six angle-beam transducers generate shear waves in the tubes. Two of the six are oriented to detect circumferential cracks, and two detect axial cracks. Although each of these four transducers is used in the pulse-echo mode, they are oriented in aligned sets so pitch-catch operation is possible if desired. The remaining angle-beam transducers are angulated to detect flaws that are off axial or circumferential orientation. The seventh transducer is used for longitudinal inspection and detects and sizes laminar-type defects

  5. Vaccine candidates for malaria: what's new?

    Science.gov (United States)

    Takashima, Eizo; Morita, Masayuki; Tsuboi, Takafumi

    2016-01-01

    Although it is more than a decade since the parasite genome information was obtained, standardized novel genome-wide selection/prioritization strategies for candidacy of malaria vaccine antigens are still sought. In the quest to systematically identify candidates, it is impossible to overemphasize the usefulness of wheat germ cell-free technology in expressing quality proteins for the post-genome vaccine candidate discovery. PMID:26559316

  6. Defensin-like polypeptide LUREs are pollen tube attractants secreted from synergid cells.

    Science.gov (United States)

    Okuda, Satohiro; Tsutsui, Hiroki; Shiina, Keiko; Sprunck, Stefanie; Takeuchi, Hidenori; Yui, Ryoko; Kasahara, Ryushiro D; Hamamura, Yuki; Mizukami, Akane; Susaki, Daichi; Kawano, Nao; Sakakibara, Takashi; Namiki, Shoko; Itoh, Kie; Otsuka, Kurataka; Matsuzaki, Motomichi; Nozaki, Hisayoshi; Kuroiwa, Tsuneyoshi; Nakano, Akihiko; Kanaoka, Masahiro M; Dresselhaus, Thomas; Sasaki, Narie; Higashiyama, Tetsuya

    2009-03-19

    For more than 140 years, pollen tube guidance in flowering plants has been thought to be mediated by chemoattractants derived from target ovules. However, there has been no convincing evidence of any particular molecule being the true attractant that actually controls the navigation of pollen tubes towards ovules. Emerging data indicate that two synergid cells on the side of the egg cell emit a diffusible, species-specific signal to attract the pollen tube at the last step of pollen tube guidance. Here we report that secreted, cysteine-rich polypeptides (CRPs) in a subgroup of defensin-like proteins are attractants derived from the synergid cells. We isolated synergid cells of Torenia fournieri, a unique plant with a protruding embryo sac, to identify transcripts encoding secreted proteins as candidate molecules for the chemoattractant(s). We found two CRPs, abundantly and predominantly expressed in the synergid cell, which are secreted to the surface of the egg apparatus. Moreover, they showed activity in vitro to attract competent pollen tubes of their own species and were named as LUREs. Injection of morpholino antisense oligomers against the LUREs impaired pollen tube attraction, supporting the finding that LUREs are the attractants derived from the synergid cells of T. fournieri. PMID:19295610

  7. Fuel cladding tubes and manufacture thereof

    International Nuclear Information System (INIS)

    Purpose: To enable smooth contaction between fuel pellets and cladding tubes, as well as prevent chemical reaction for the fission products released from the pellets. Method: The inner surface of a cladding tube is coated with a copper film and further provided thereover with a graphite film. The graphite film is formed through electrophoretic coating as follows: A cladding tube is supported rotatably in an electrophoretic coating tank containing coating solution incorporated with graphite powder and connected to an anode. A cathode is attached to the inside of the cladding tube. Coating current is supplied while rotating the cladding tube and the graphite film is formed through electrophoresis. (Ikeda, J.)

  8. Turbine nozzle stage having thermocouple guide tube

    Science.gov (United States)

    Schotsch, Margaret Jones; Kirkpatrick, Francis Lawrence; Lapine, Eric Michael

    2002-01-01

    A guide tube is fixed adjacent opposite ends in outer and inner covers of a nozzle stage segment. The guide tube is serpentine in shape between the outer and inner covers and extends through a nozzle vane. An insert is disposed in the nozzle vane and has apertures to accommodate serpentine portions of the guide tube. Cooling steam is also supplied through chambers of the insert on opposite sides of a central insert chamber containing the guide tube. The opposite ends of the guide tube are fixed to sleeves, in turn fixed to the outer and inner covers.

  9. Ceramic vacuum tubes for geothermal well logging

    Energy Technology Data Exchange (ETDEWEB)

    Kelly, R.D.

    1977-01-12

    The results of investigations carried out into the availability and suitability of ceramic vacuum tubes for the development of logging tools for geothermal wells are summarized. Design data acquired in the evaluation of ceramic vacuum tubes for the development of a 500/sup 0/C instrumentation amplifier are presented. The general requirements for ceramic vacuum tubes for application to the development of high temperature well logs are discussed. Commercially available tubes are described and future contract activities that specifically relate to ceramic vacuum tubes are detailed. Supplemental data is presented in the appendix. (MHR)

  10. Small size neutron tube UNG-1

    International Nuclear Information System (INIS)

    A tube UNG-1 (universal neutron gas-filled) is designed for the use in the well neutron generators IGN-1 and IGN-1-M (a pulse neutron generator). Their serial production in the USSR has been started in 1963. At the same year, the serial production of the tubes UNG-1 has been started. Thus, this tube is the first serial logging accelerating tube in the USSR. A Penning source, equipped with a hot cathode, was selected as an ion source of the tube

  11. Explosive Ballooning Flux Tubes in Tokamaks

    CERN Document Server

    Ham, C J; Brochard, G; Wilson, H R

    2016-01-01

    Tokamak stability to, potentially explosive, `ballooning' displacements of elliptical magnetic flux tubes is examined in large aspect ratio equilibrium. Above a critical pressure gradient the energy stored in the plasma may be lowered by finite (but not infinitesimal) displacements of such tubes (metastability). Above a higher pressure gradient, the linear stability boundary, such tubes are linearly and nonlinearly unstable. The flux tube displacement can be of the order of the pressure gradient scale length. Plasma transport from displaced flux tubes may result in rapid loss of confinement.

  12. Cardiac evaluation of liver transplant candidates

    Institute of Scientific and Technical Information of China (English)

    Mercedes Susan Mandell; JoAnn Lindenfeld; Mei-Yung Tsou; Michael Zimmerman

    2008-01-01

    Physicians previously thought that heart disease was rare in patients with end stage liver disease. However, recent evidence shows that the prevalence of ischemic heart disease and cardiomyopathy is increased in transplant candidates compared to most other surgical candidates. Investigators estimate that up to 26% of all liver transplant candidates have at least one critical coronary artery stenosis and that at least half of these patients will die perioperatively of cardiac complications. Cardiomyopathy also occurs in greater frequency. While all patients with advanced cardiac disease have defects in cardiac performance, a larger than expected number of patients have classical findings of dilated, restrictive and hypertropic cardiomyopathy. This may explain why up to 56% of patients suffer from hypoxemia due to pulmonary edema following transplant surgery. There is considerable controversy on how to screen transplant candidates for the presence of heart disease. Questions focus upon, which patients should be screened and what tests should be used. This review examines screening strategies for transplant candidates and details the prognostic value of common tests used to identify ischemic heart disease. We also review the physiological consequences of cardiomyopathy in transplant candidates and explore the specific syndrome of "cirrhotic cardiomyopathy".

  13. Capillary Hemangioma of the Fallopian Tube.

    Science.gov (United States)

    Katiyar, Richa; Patne, Shashikant C U; Bharti, Shreekant; Jain, Madhu

    2016-04-01

    Neoplastic lesions of the fallopian tube are rarely seen by surgical pathologists. Haemangioma of the fallopian tube is an extremely rare benign neoplasm. A 30-year-old lady with polymenorrhea and dysmenorrhea underwent hysterectomy and bilateral salpingo-oophorectomy. Her left fallopian tube showed a 2mm sized solid nodule in the wall. Histopathological examination revealed a well-defined vascular lesion in the left fallopian tube, consistent with capillary haemangioma. The vascular endothelium was highlighted by CD34 immunostaining. Our literature review has identified 10 cases of cavernous haemangioma of the fallopian tube. To the best of our knowledge, we report the first ever case of capillary haemangioma of the fallopian tube. This is also the smallest detected haemangioma in the fallopian tube. PMID:27190899

  14. Performance of the Hamamatsu R11410 photomultiplier tube in cryogenic xenon environments

    International Nuclear Information System (INIS)

    The Hamamatsu R11410 photomultiplier, a tube of 3'' diameter and with a very low intrinsic radioactivity, is an interesting light sensor candidate for future experiments using liquid xenon (LXe) as target for direct dark matter searches. We have performed several experiments with the R11410 with the goal of testing its performance in environments similar to a dark matter detector setup. In particular, we examined its long-term behavior and stability in LXe and its response in various electric field configurations.

  15. Bearing pad to pressure tube contact simulation

    International Nuclear Information System (INIS)

    Thermal creep strain deformation is a very important pressure tube failure mechanism. During a postulated LOCA (loss of coolant accident) with failure of emergency core injection sys- tem (ECIS), the fuel cladding temperature rapidly increases and the pressure tube becomes completely dry in a few seconds after flow stagnation occurs. Subsequently, the pressure tube circumference is heated by thermal radiation except at the spots where the bearing pads are in direct contact with the pressure tube. Therefore, the localized hot spots are developed on the pressure tube's inner surface under the bearing pads. The main objective of this paper is to evaluate the local thermal-mechanical deformation of a pressure tube in a CANDU reactor and to investigate the fuel channel integrity under localized contact between bearing pad and pressure tube. Furthermore, the mechanistic models are validated against the experimental works per- formed at WRL (Whiteshell research laboratory). Calculations are performed using the finite element method in which the heat, thermal mechanical and creep strain equations are solved, simultaneously. According to the experimental set up, the heat conduction from bearing pads to the inner surface of the pressure tube with appropriate convective and radiation boundary conditions has been simulated. Furthermore, the thermal creep strain deformation has been obtained for when the pressure tube is still under operational condition. It is observed that the pressure tube thermal strain will occur if sufficient high temperature is reached however, depending on the severity of flow degradation in the fuel channel, these localized hot spots could represent a potential creep strain failure of the pressure tube. Whether the pressure tube would fail at these hot spots before contacting the calandria tube depends on the localized temperature and experienced pressure transients. Sensitivity analysis is performed in order to evaluate the contact conductance, the

  16. Heat transfer parameters for glass-peened calandria tube in pressure tube and calandria tube contact conditions

    International Nuclear Information System (INIS)

    During a postulated event of large LOCA in CANDU reactors, the pressure tube may balloon to contact with its surrounding calandria tube to transfer heat to the moderator. To confirm the integrity of the fuel channel after the contact with a given moderator subcooling, many experiments have been performed in the last three decades by applying different pressure tube heatup rates, different pressure tube pressures and different moderator subcoolings for calandria tubes with smooth outer surface and glass-peened surface. A concept of Equivalent Moderator Subcooling (EMS) has been put forward to determine integrity of fuel channel upon pressure tube/calandria tube contact based on the existing experiment results. This concept has been presented in another work. In this work, the contact thermal conductance between pressure tube and calandria tube, critical heat flux, minimum film boiling temperature, empirical methods for nucleate boiling and film boiling heat transfer coefficient on the glass-peened calandria tube surface are discussed and estimated based on some experimental results and the EMS concept. These parameters are confirmed by simulating the existing experiments using a computer code. The estimated results may help detailed analyses on fuel channel integrity upon PT/CT contact if necessary. (author)

  17. NASA Lewis Stirling SPRE testing and analysis with reduced number of cooler tubes

    International Nuclear Information System (INIS)

    Free-piston Stirling power converters are a candidate for high capacity space power applications. The Space Power Research Engine (SPRE), a free-piston Stirling engine coupled with a linear alternator, is being tested at the NASA Lewis Research Center in support of the Civil Space Technology Initiative. The SPRE is used as a test bed for evaluating converter modifications which have the potential to improve converter performance and for validating computer code predictions. Reducing the number of cooler tubes on the SPRE has been identified as a modification with the potential to significantly improve power and efficiency. This paper describes experimental tests designed to investigate the effects of reducing the number of cooler tubes on converter power, efficiency and dynamics. Presented are test results from the converter operating with a reduced number of cooler tubes and comparisons between this data and both baseline test data and computer code predictions

  18. Pulse tube cooler having 1/4 wavelength resonator tube instead of reservoir

    Science.gov (United States)

    Gedeon, David R. (Inventor)

    2008-01-01

    An improved pulse tube cooler having a resonator tube connected in place of a compliance volume or reservoir. The resonator tube has a length substantially equal to an integer multiple of 1/4 wavelength of an acoustic wave in the working gas within the resonator tube at its operating frequency, temperature and pressure. Preferably, the resonator tube is formed integrally with the inertance tube as a single, integral tube with a length approximately 1/2 of that wavelength. Also preferably, the integral tube is spaced outwardly from and coiled around the connection of the regenerator to the pulse tube at a cold region of the cooler and the turns of the coil are thermally bonded together to improve heat conduction through the coil.

  19. Effect of U-tube length on space distribution of UTSG reverse flow in tubes

    International Nuclear Information System (INIS)

    For natural circulation, it is shown that parallel flow in the tubes of inverted U-tube steam generators can be non-uniform. And reverse flow occurs in some tubes. Existing studies on the space distribution of reverse flow tubes are dissident. A flow model of one-dimensional steady state is established. Analysis shows that the length will change the relationship of flow characteristics between tubes. And the space distribution of reverse flow tube differs further. When the U-tube length of UTSG is small enough, flow excursion will occur earlier in shorter tube than longer tube, and vise versa. And the analysis is validated by best estimate code RELAP5/MOD3.3. (authors)

  20. Vacuum and the electron tube industry

    Science.gov (United States)

    Redhead, P. A.

    2005-07-01

    The electron tube industry started with the patenting of the thermionic diode by John Ambrose Fleming in 1904. The vacuum technology used by the infant tube industry was copied from the existing incandescent lamp industry. The growing demands for electron tubes for the military in the first world war led to major improvements in pumps and processing methods. By the 1920s, mass production methods were developing to satisfy the demands for receiving tubes by the burgeoning radio industry. Further expansion in the 1930s and 1940s resulted in improvements in automatic equipment for pumping vacuum tubes leading to the massive production rates of electron tubes in the second world war and the following two decades. The demand for radar during the war resulted in the development of techniques for large-scale production of microwave tubes and CRTs, the latter technology being put to good use later in TV picture tube production. The commercial introduction of the transistor ended the massive demand for receiving tubes. This review concentrates on the vacuum technology developed for receiving tube production.

  1. Evaluating historical candidate genes for schizophrenia.

    Science.gov (United States)

    Farrell, M S; Werge, T; Sklar, P; Owen, M J; Ophoff, R A; O'Donovan, M C; Corvin, A; Cichon, S; Sullivan, P F

    2015-05-01

    Prior to the genome-wide association era, candidate gene studies were a major approach in schizophrenia genetics. In this invited review, we consider the current status of 25 historical candidate genes for schizophrenia (for example, COMT, DISC1, DTNBP1 and NRG1). The initial study for 24 of these genes explicitly evaluated common variant hypotheses about schizophrenia. Our evaluation included a meta-analysis of the candidate gene literature, incorporation of the results of the largest genomic study yet published for schizophrenia, ratings from informed researchers who have published on these genes, and ratings from 24 schizophrenia geneticists. On the basis of current empirical evidence and mostly consensual assessments of informed opinion, it appears that the historical candidate gene literature did not yield clear insights into the genetic basis of schizophrenia. A likely reason why historical candidate gene studies did not achieve their primary aims is inadequate statistical power. However, the considerable efforts embodied in these early studies unquestionably set the stage for current successes in genomic approaches to schizophrenia. PMID:25754081

  2. Development of INCONEL 600 precision tube (1)

    Energy Technology Data Exchange (ETDEWEB)

    Joo, Yeong Han; Jo, Bong Hyeon; Lee, Dong Hee; Kim, Wan Kyo; Jeong, Pyeong Keun; Yoon, Hwang Lo; Chio, Seok Sik [Sammi Steel Co. Ltd., Changwon (Korea, Republic of)

    1994-07-01

    Steam generator, being connected with nuclear fuel reactor is one of the most important part of nuclear power plant and consists of a large number of INCONEL 600 tubes. Approximately 160 tons of tubes are needed for a single nuclear power plant. All of INCONEL 600 steam generator tubes for domestic nuclear power plants have been imported. The aim of this research is to develop INCONEL 600 precision tubes for steam generator of nuclear power plant. If this research is conducted successfully, we can produce nuclear fuel tubes, Ni-alloy precision tubes and stainless steel precision tubes for many purposes and technology of INCONEL 600 steam generator tubes are similar to those of other tubes above mentioned. In the current study, development of preliminary manufacturing process of INCONEL 600 precision tubes for steam generator and investigation of material`s metallurgical characteristics were conducted. The main scope of this research is as follows. First, the preliminary manufacturing process design was conducted after investigations of foreign manufacturing processes and technical reports. Second, the results of investigations of material`s metallurgical characteristics through the manufacturing process were applied to the production technology of tentative INCONEL 600 precision tubes for sample. Third, preliminary process routes were established and samples of INCONEL 600 precision tube were produced by this process. As the results of this research, 14 pieces of INCONEL 600 precision tubes were produced by preliminary manufacturing process and the material`s metallurgical characteristics were investigated through the processes. But the SCC test could not be conducted due to the absence of equipment. In order to apply the results of SCC test to the manufacturing process, we need a SCC tester which can simulate SCC characteristics under high temperature and high pressurized circulating water. 95 refs., 55 figs., 20 tabs.

  3. Eddy current inspection of tubing

    International Nuclear Information System (INIS)

    The Experimental research work carried out to develop a Eddy current testing equipment is described. Search coils with ferrite or air cores were used and the obtained results are discussed. Valuable information was gained from a improved channel in which a direct measure of the defect and the reference signal phase difference is obtained. Artificial defect used to evaluate resolution and sensitivity were produced by electro-machining and mechanical means. Finned SAP tubing was tested in a routine basis with the described equipment and the results plotted. Basic and theoretical considerations on the Eddy current testing technique are given in the last section of this report. (Author)

  4. Improved Traveling-Wave Tube

    Science.gov (United States)

    Rousseau, Art; Tammaru, Ivo; Vaszari, John

    1988-01-01

    New space traveling-wave tube (TWT) provides coherent source of 75 watts of continuous-wave power output over bandwidth of 5 GHz at frequency of 65 GHz. Coupled-cavity TWT provides 50 dB of saturated gain. Includes thermionic emitter, M-type dispenser cathode providing high-power electron beam. Beam focused by permanent magnets through center of radio-frequency cavity structure. Designed for reliable operation for 10 years, and overall efficiency of 35 percent minimizes prime power input and dissipation of heat.

  5. Steam generator tube laser sleeving

    International Nuclear Information System (INIS)

    For many years, Framatome has been used with different techniques and means to perform the steam generator tube sleeving operation, such as the 'mechanical' either GTAW welded or kinetic welding process. As soon as first power laser units appeared on the market we felt right interested in applying this process to the sleeving operation. After comparison between all the processes and equipments existing at that time (that is to say CO2 and YAG laser units), we chose the YAG and bought a 1.2 kW NEC laser unit in 1988. As it was installed in our Welding Center of Le Creusot, this equipment enabled us carrying out a preliminary test programme which targets were: getting the mastery of the equipment and associated technologies, implementing this process for the sleeve welding operation by improvement of the welding-pen. The NEC laser unit became afterwards transferred to our workshop in Chalon-sur-Saone (June 1990), where we achieved the final tests of the process at the same time we were investigating the development of industrial operation means. The actual program is mainly focused on 7/8'' tube steam generator repair process at tubesheet outlet. Yet made sure that our methods and means apply as well to 3/4'' tubes up to second tube support-plate level. Sleeves are made of heat-treated Inconel 690. The sleeved unit has been designed to provide the same breaking strength and leak-tightness as the tube. The upper part of sleeve consists of an anti-pop out length which ensures some locking-up in case the tube breaks in upper transition expansion area. Preliminary tests dealt with the various parameters which may exert an influence on geometry and quality of the, weld bead, as: - laser beam power (for continuous and pulsed modes), - welding speed, - focal spot size and location from the surface to be welded, - protective gas. After performance of preliminary tests on many thousands of weld beads we decided to use the process according to following criteria: Weld quality

  6. Afterpulse measurement for 8-inch candidate PMTs for LHAASO

    Science.gov (United States)

    Zhao, X.; Tang, Z.; Li, C.; Chen, H.; Zhang, Y.; Li, X.; Shao, M.; Sun, Y.; Zha, W.; Zhou, Y.

    2016-05-01

    An afterpulse occurs within a short time after the main pulse and cannot be directly distinguished from the true physical signals. In cosmic ray experiments, a large number of photomultiplier tubes (PMTs) are used, which means the occurrence of afterpulses leads to a significant background. Therefore, before PMTs are employed, their afterpulse characteristics need to be evaluated to make sure they perform as expected. To evaluate the impact of afterpulses, we investigate the afterpulses for the Hamamatsu PMT R5912 (a candidate of the WCDA and MD for LHAASO) using two different electronic testing systems. First, we measured the characteristics of afterpulses in detail using a frequency-tunable flash analog-to-digital converter (ADC) with a time window of up to 15 μ s after a laser signal. We measured the time delay with respect to the main pulse, the amplitude, and the rate of the afterpulse dependence, on the main signal amplitude and the applied high voltage. Second, we developed a system that uses a multi-hit time-to-digital converter (multi-hit TDC), which allows for much faster measurement of the afterpulse rates, in order to make it possible to test up to 5000 large-sized PMTs.

  7. Closing the door on dark matter candidates

    International Nuclear Information System (INIS)

    Cold dark matter candidates - if they exist - will be present in, and perhaps dominate the mass density of, the halo of our Galaxy. As they pass the vicinity of the Sun, such halo particles will be focussed gravitationally, pass through the Sun and - occasionally - be captured and accumulate in the solar core. When the density in the core of the Sun of dark matter candidates has increased sufficiently, they will annihilate and among the annihilation products will be energetic (≥ GeV) ''ordinary'' neutrinos (νe, νμ, ντ) which are detectable in deep underground experiments. The event rates in such detectors from the capture and annihilation of various dark matter candidates (Dirac and Majorana neutrinos, Sneutrinos and Photinos) are presented and it is shown how comparison with data may lead to constraints on (or, the exclusion of) the masses of these particles. 6 refs

  8. Adsorption of Urinary Proteins on the Conventionally Used Urine Collection Tubes: Possible Effects on Urinary Proteome Analysis and Prevention of the Adsorption by Polymer Coating

    OpenAIRE

    Iwao Kiyokawa; Kazuyuki Sogawa; Keiko Ise; Fumie Iida; Mamoru Satoh; Toshihide Miura; Ryo Kojima; Katsuhiro Katayama; Fumio Nomura

    2011-01-01

    One possible factor determining recovery of trace amount of protein biomarker candidates during proteome analyses could be adsorption on urine tubes. This issue, however, has not been well addressed so far. Recently, a new technical device of surface coating by poly(2-methacryloyloxyethyl phosphorylcholine (MPC)-co-n-butyl methacrylate (BMA)) (poly(MPC-co-BMA)) has been developed mainly to prevent the adsorption of plasma proteins. We assessed whether conventionally used urine tubes adsorb tr...

  9. [How to do - the chest tube drainage].

    Science.gov (United States)

    Klopp, Michael; Hoffmann, Hans; Dienemann, Hendrik

    2015-03-01

    A chest tube is used to drain the contents of the pleural space to reconstitute the physiologic pressures within the pleural space and to allow the lungs to fully expand. Indications for chest tube placement include pneumothorax, hemothorax, pleural effusion, pleural empyema, and major thoracic surgery. The most appropriate site for chest tube placement is the 4th or 5th intercostal space in the mid- or anterior- axillary line. Attention to technique in placing the chest tube is vital to avoid complications from the procedure. Applying the step-by-step technique presented, placement of a chest tube is a quick and safe procedure. Complications - frequently occurring when the tube is inserted with a steel trocar - include hemothorax, dislocation, lung lacerations, and injury to organs in the thoracic or abdominal cavity." PMID:25734676

  10. Development of a supermirror neutron guide tube

    International Nuclear Information System (INIS)

    A supermirror neutron guide tube with a characteristic wavelength of 1.2 A was developed and installed at the Kyoto University Reactor (KUR). The apparent critical wavelength of the present supermirrors is about 250 A. The geometrical parameters of the guide tube are : 11.7 m total length, and 10 mm wide x 74 mm high beam cross section. The supermirror neutron guide tube presents decisive advantages over the conventional nickel mirror guide tube higher transmission of neutrons, brought about through the contribution of neutrons of shorter wavelengths and of those presenting large divergent angles. The total neutron flux obtained from the KUR supermirror guide tube is about 5 x 107 n/cm2 · s, which is about 25 times what is obtainable with the conventional KUR nickel mirror neutron guide tube of the same geometrical parameters. (author)

  11. Ballooning of CANDU pressure tubes. Model assessment

    International Nuclear Information System (INIS)

    The transient creep equations used to analyze the possible ballooning and failure of Zr-2.5% Nb pressure tubes during a loss-of-coolant accident (LOCA) were developed and verified using as-received Zr-2.5% Nb pressure tube material. But in a CANDU reactor, the pressure tubes absorb deuterium and are exposed to a continuous neutron fluence. Consequently, a literature survey was done to determine how irradiation damage and deuterium might affect the creep rate and ductility of Zr-2.5% Nb pressure tubes in the temperature range from 600 to 800 degrees C. It was found that irradiation damage, dissolved deuterium and deuteride blisters could possibly affect the creep rate and ductility of ZR-2.5% Nb pressure tubes in this temperature range, but deuteride platelets are expected to have little effect. Further tests are required to determine the effect of irradiation damage and deuterium on the creep rate and ductility of pressure tubes

  12. CFD Simulation on Ethylene Furnace Reactor Tubes

    Institute of Scientific and Technical Information of China (English)

    2006-01-01

    Different mathematical models for ethylene furnace reactor tubes were reviewed. On the basis of these models a new mathematical simulation approach for reactor tubes based on computational fluid dynamics (CFD) technique was presented. This approach took the flow, heat transfer, mass transfer and thermal cracking reactions in the reactor tubes into consideration. The coupled reactor model was solved with the SIMPLE algorithm. Some detailed information about the flow field, temperature field and concentration distribution in the reactor tubes was obtained, revealing the basic characteristics of the hydrodynamic phenomena and reaction behavior in the reactor tubes. The CFD approach provides the necessary information for conclusive decisions regarding the production optimization, the design and improvement of reactor tubes, and the new techniques implementation.

  13. Precision alignment of permanent magnet drift tubes

    International Nuclear Information System (INIS)

    The Lawrence Berkeley National Laboratory (LBNL) technique of drift-tube alignment has been resurrected at Los Alamos for the precision alignment of 1-cm-core drift tubes that carry high gradient rare-earth-cobalt quadrupoles. Because the quadrupoles cannot be switched off, this technique is not applicable to a drift-tube assembly, but tests indicate that individual magnetic centers can be detected with a precision of +/-0.003 mm. Methods of transferring this information to machined alignment flats on the sides of the drift-tube body are discussed. With measurements of drift tubes designed for a 100-mA, 425-MHz drift-tube linac, offsets between the geometric and magnetic axes of up to +/-0.05 mm were detected following final assembly and welding. This degree of offset is serious if not accommodated, because it represents the entire alignment tolerance for the 40-cell tank. The measurement equipment and technique are described

  14. Cattle Candidate Genes for Meat Production Traits

    OpenAIRE

    Bláhová, Alice

    2013-01-01

    The objective of this study was to compile a summary of the most important candidate genes for meat production. The studied genes were: GH, GHR, MSTN, MyoD family, leptin, IGF, TG5, SCD, DGAT and STAT5A. Growth hormone (GH) is involved in physiological processes of growth and metabolism. Growth hormone receptor (GHR) has been proposed as a candidate gene for meat production in cattle. Myostatin is a significant marker. It affects the amount of muscle, reduces marbling and elevate meat tendern...

  15. Characterization of the Hamamatsu R11780 12 inch Photomultiplier Tube

    CERN Document Server

    Brack, J; Dhooghe, J; Felde, J; Gookin, B; Grullon, S; Klein, J R; Knapik, R; LaTorre, A; Seibert, S; Shapiro, K; Svoboda, R; Ware, L; Van Berg, R

    2012-01-01

    Future large water Cherenkov and scintillator detectors have been proposed for measurements of long baseline neutrino oscillations, proton decay, supernova and solar neutrinos. To ensure cost-effectiveness and optimize scientific reach, one of the critical requirements for such detectors are large-area, high performance photomultiplier tubes (PMTs). One candidate for such a device is the Hamamatsu R11780, a 12" PMT that is available in both standard and high quantum efficiency versions. Measurements of the single photoelectron response characteristics, relative efficiencies of the standard and high quantum efficiency versions, a preliminary measurement of the absolute quantum efficiency of the standard quantum efficiency version, and a two-dimensional scan of the relative efficiency across the photocathode surface are presented in this paper. All single photoelectron investigations were made using a Cherenkov light source at room temperature at a gain of 1*10^7. These results show that the R11780 PMT is a exc...

  16. Torsional Stability of Aluminum Alloy Seamless Tubing

    Science.gov (United States)

    Moore, R L; Paul, D A

    1939-01-01

    Torsion tests were made on 51ST aluminum-alloy seamless tubes having diameter-to-thickness ratios of from 77 to 139 and length-to-diameter ratios of from 1 to 60. The torsional strengths developed in the tubes which failed elastically (all tubes having lengths greater than 2 to 6 times the diameter) were in most cases within 10 percent of the value indicated by the theories of Donnel, Timoshenko, and Sturm, assuming a condition of simply supported ends.

  17. Single photon response of photomultiplier tubes

    International Nuclear Information System (INIS)

    Beta or gamma rays, when directly incident on the window of an optically shielded photomultiplier tube, yield a typical single photon spectrum. The single photons are possibly generated in the glass window of the photomultiplier tube through excitation of atoms in glass by electrons. The coincidence resolving time has also been measured with a 60Co gamma source and a pair of optically shielded photomultiplier tubes detecting single photons. (orig.)

  18. Literature search for ceramic vacuum tubes

    Energy Technology Data Exchange (ETDEWEB)

    Cannon, W.

    1977-01-12

    The NTIS and Engineering Index files were searched for citations relating to Ceramic and/or Metal Electron Tubes and High Temperature Electronics. A total of 24 citations were found relating directly to ceramic tubes and 24 to high temperature electronics. A search for electron tubes in general was examined for high temperature applications and 39 were obtained. Computer printouts of the abstracts are included in appendices. (MHR)

  19. DEVELOPMENT OF COILED TUBING STRESS ANALYSIS

    Directory of Open Access Journals (Sweden)

    Davorin Matanović

    1998-12-01

    Full Text Available The use of coiled tubing is increasing rapidly with drilling of horizontal wells. To satisfy all requirements (larger mechanical stresses, larger fluid capacities the production of larger sizes and better material qualities was developed. Stresses due to axial forces and pressures that coiled tubing is subjected are close to its performance limits. So it is really important to know and understand the behaviour of coiled tubing to avoid its break, burst or collapse in the well.

  20. Tube-in-shell heat exchangers

    International Nuclear Information System (INIS)

    A tube-in-shell heat exchanger is described for use in liquid metal cooled fast breeder reactor constructions. The system consists of a bundle of heat exchange tubes with a central spine extending longitudinally through the shell and a series of longitudinally spaced transverse grids resiliently mounted on the central spine within the shell to provide transverse support for bracing the tubes apart. (U.K.)

  1. Ballooning of CANDU pressure tubes - experiments with degraded tube material

    International Nuclear Information System (INIS)

    Three as-received Zr-2.5% Nb pressure tube specimens and three specimens with eight 0.5 mm deep defects machined on the inside surface were tested in the ballooning test rig at Stern Laboratories Inc. The temperature ramp rate was controlled between 28 K s-1 and 35 K s-1. Temperatures on the outside and inside surfaces of the specimens, and circumferential and longitudinal strains were recorded during the transients. Post-test longitudinal, circumferential and wall thickness strains were measured. All as-received specimens ruptured full-length near the top, i.e., the hottest point. All defected specimens failed at either or both upper defects, one rupture being full-length and the others limited to one to three times the length of the defect. (author). 4 refs., 2 tabs., 15 figs

  2. Bottom nozzle to guide tube connection

    International Nuclear Information System (INIS)

    This patent describes a nuclear fuel assembly which includes an upper end fitting and a lower end fitting spaced therefrom and connected thereto by elongated guide tubes of one alloy having an open upper end and a closed lower end with spaced fuel element retaining grids mounted on the guide tubes therebetween, the closed lower ends of the guide tubes including a threaded central passageway and the attachment of the guide tubes to the lower end fitting of another alloy. It comprises: an externally threaded bolt with a first end threadably received in the threaded central passageway of the lower end of the guide tube and a head at the other end of the side of the lower end fitting opposite the guide tube; an interruption in the external threads of the bolt which forms a groove which communicates the interior of the guide tube with the side of the lower end fitting opposite the guide tube and enhances its frictional engagement with the threaded central passageway, thereby to hold and attach the guide tube and lower end fitting firmly together, even through a series of temperature cycles

  3. Reducing gain shifts in photomultiplier tubes

    Science.gov (United States)

    Cohn, Charles E.

    1976-01-01

    A means is provided for reducing gain shifts in multiplier tubes due to varying event count rates. It includes means for limiting the number of cascaded, active dynodes of the multiplier tube to a predetermined number with the last of predetermined number of dynodes being the output terminal of the tube. This output is applied to an amplifier to make up for the gain sacrificed by not totally utilizing all available active stages of the tube. Further reduction is obtained by illuminating the predetermined number of dynodes with a light source of such intensity that noise appearing at the output dynode associated with the illumination is negligible.

  4. Bleed condenser tube failure in KAPP-1

    International Nuclear Information System (INIS)

    Bleed condenser, a vertical, tube and shell type heat exchanger employed in bleed circuit of primary heat transport system of PHWR is used for condensing the flashing bleed (heavy water) on shell side and cold heavy water on the tubes side. Examinations conducted at various places indicate failure due to inadequate tube expansion (hydraulic expansion) followed by crevice corrosion. Mechanical rolling of tubes to larger extent (3 to 6% wall thinning) have been specified for this particular type of service in all bleed condensers for subsequent projects. 1 tab., 4 figs

  5. Small bowel perforation during suprapubic tube exchange.

    Science.gov (United States)

    Mongiu, Anne K; Helfand, Brain T; Kielb, Stephanie J

    2009-02-01

    Suprapubic tube placement is a common urological procedure with a low incidence of complications, including hematuria, catheter blockage, recurrent urinary tract infections, and rarely, injury to adjacent organs. Fortunately, most serious complications are discovered shortly after initial suprapubic tube placement and are readily corrected. Very few cases of delayed complications or injuries have been reported. We report a case of Foley perforation into the ileum during suprapubic tube exchange discovered more than 8 months after initial placement, and preceding numerous monthly changes that occurred without incident. While a rare complication, physicians should be conscious of the potential for delayed injury in patients managed with long term suprapubic tube placement. PMID:19222896

  6. Modeling Pulse Tube Cryocoolers with CFD

    Science.gov (United States)

    Flake, Barrett; Razani, Arsalan

    2004-06-01

    A commercial computational fluid dynamics (CFD) software package is used to model the oscillating flow inside a pulse tube cryocooler. Capabilities for modeling pulse tubes are demonstrated with preliminary case studies and the results presented. The 2D axi-symmetric simulations demonstrate the time varying temperature and velocity fields in the tube along with computation of the heat fluxes at the hot and cold heat exchangers. The only externally imposed boundary conditions are a cyclically moving piston wall at one end of the tube and constant temperature or heat flux boundaries at the external walls of the hot and cold heat exchangers.

  7. GEIGER-MULLER TYPE COUNTER TUBE

    Science.gov (United States)

    Fowler, I.L.; Watt, L.A.K.

    1959-12-15

    A single counter tube capable of responding to a wide range of intensities is described. The counter tube comprises a tubular cathode and an anode extending centrally of the cathode. The spacing between the outer surface of the anode and the inner surface of the cathode is varied along the length of the tube to provide different counting volumes in adjacent portions of the tube. A large counting volume in one portion adjacent to a low-energy absorption window gives adequate sensitivity for measuring lowintensity radiation, while a smaller volume with close electrode spacing is provided in the counter to make possible measurement of intense garnma radiation fields.

  8. Micro tube heat exchangers for Space Project

    Data.gov (United States)

    National Aeronautics and Space Administration — Mezzo fabricates micro tube heat exchangers for a variety of applications, including aerospace, automotive racing, Department of Defense ground vehicles,...

  9. Development and study on vacuum absorber tubes

    Energy Technology Data Exchange (ETDEWEB)

    Wang, Jun; Zhang, Yaoming [Southeast Univ., Hohai Univ., Nanjing (China); Liu, Deyou; An, cuicui [Hohai Univ., Nanjing (China)

    2008-07-01

    A new type solar vacuum absorber tube has been developed, and the tensile tests have shown the high reliability of the joint between the metal and glass of the vacuum absorber tube; the fatigue tests have indicated that the bellows of the vacuum absorber tube as well as the interface between the metal and glass can last for as long as 20 years; the weathering tests of the sample, have lasted for an entire year, which proves that the tube design is scientifically and reasonably devised. (orig.)

  10. Eddy-Current Detection of Cracks in Tubes

    Science.gov (United States)

    Parent, R.; Kettering, D.

    1987-01-01

    Nondestructive device tests narrow, sharply-bent metal tubes. Eddycurrent probe detects incipient cracks inside small metal tubes. Tube-centering device consisting of pair of opposed bars ensures tube centered on eddy-current coil. Probe moves along length of bent tube to inspect repeatably for cracks. Compatible with tubes of different cross sections, oval, flattened, square, rectangular,or irregular. Adapts for inspecting formed tubes in petrochemical, automotive, nuclear, and medical equipment.

  11. Preanalytical management: serum vacuum tubes validation for routine clinical chemistry

    OpenAIRE

    Lima-Oliveira, Gabriel; Lippi, Giuseppe; Salvagno, Gian Luca; Montagnana, Martina; Picheth, Geraldo; Guidi, Gian Cesare

    2012-01-01

    Introduction: The validation process is essential in accredited clinical laboratories. Aim of this study was to validate five kinds of serum vacuum tubes for routine clinical chemistry laboratory testing. Materials and methods: Blood specimens from 100 volunteers in five different serum vacuum tubes (Tube I: VACUETTE®, Tube II: LABOR IMPORT®, Tube III: S-Monovette®, Tube IV: SST® and Tube V: SST II®) were collected by a single, expert phlebotomist. The routine clinical chemistry tests were...

  12. Promoting Team Leadership Skills in Doctoral Candidates

    Science.gov (United States)

    Suleiman, Mahmoud; Whetton, Danny

    2014-01-01

    Doctoral programs can serve as an optimal opportunity for candidates to engage in tasks and activities to transform them and their schools. The paradigm shifts in such preparation involve moving from sitting and getting to making and taking. Most importantly, it requires building leadership skills and styles necessary to bring about desired change…

  13. Secondary Teacher Candidates' Lesson Planning Learning

    Science.gov (United States)

    Santoyo, Christina; Zhang, Shaoan

    2016-01-01

    Teacher candidates (TCs) use clinical experiences to enact concepts taught in their university courses; therefore field experiences may be the most important component of teacher preparation (Hammerness et al., 2005). TCs require support and guidance as they learn to adapt curriculum materials for effective use in the classroom (Davis, 2006). They…

  14. The Responsibility Education of Teacher Candidates

    Science.gov (United States)

    Toremen, Fatih

    2011-01-01

    In this study, it was aimed to take the views and suggestions of academicians working at the faculty of education on what can be done about teacher candidates' responsibility education. This study was designed on the basis of qualitative research approach and purposive sampling method was used. Data were collected by unstructured interview method…

  15. Microlensing Binaries with Candidate Brown Dwarf Companions

    DEFF Research Database (Denmark)

    Shin, I.-G; Han, C.; Gould, A.;

    2012-01-01

    Brown dwarfs are important objects because they may provide a missing link between stars and planets, two populations that have dramatically different formation histories. In this paper, we present the candidate binaries with brown dwarf companions that are found by analyzing binary microlensing ...

  16. FAME's Search for Extrasolar Planet Candidates

    Science.gov (United States)

    Johnston, K.

    FAME is a five year survey mission to observe the positions, proper motions, and parallaxes of 40,000,000 stars down to 15th magnitude with accuracies of 50 microarcseconds at 9th magnitude. In addition to producing an astrometric and photometric catalog unparalleled for its accuracy and size, the survey will provide significant astrophysics results and search for extrasolar planet candidates.

  17. Query by image example: The CANDID approach

    Energy Technology Data Exchange (ETDEWEB)

    Kelly, P.M.; Cannon, M. [Los Alamos National Lab., NM (United States). Computer Research and Applications Group; Hush, D.R. [Univ. of New Mexico, Albuquerque, NM (United States). Dept. of Electrical and Computer Engineering

    1995-02-01

    CANDID (Comparison Algorithm for Navigating Digital Image Databases) was developed to enable content-based retrieval of digital imagery from large databases using a query-by-example methodology. A user provides an example image to the system, and images in the database that are similar to that example are retrieved. The development of CANDID was inspired by the N-gram approach to document fingerprinting, where a ``global signature`` is computed for every document in a database and these signatures are compared to one another to determine the similarity between any two documents. CANDID computes a global signature for every image in a database, where the signature is derived from various image features such as localized texture, shape, or color information. A distance between probability density functions of feature vectors is then used to compare signatures. In this paper, the authors present CANDID and highlight two results from their current research: subtracting a ``background`` signature from every signature in a database in an attempt to improve system performance when using inner-product similarity measures, and visualizing the contribution of individual pixels in the matching process. These ideas are applicable to any histogram-based comparison technique.

  18. Candidal Leukoplakia on Patient with Removable Denture

    Directory of Open Access Journals (Sweden)

    Shiril Paskalis

    2013-07-01

    Full Text Available Candida infection is a common problem in patients using removable dentures, with the most frequent type is denture stomatitis. But other type of candidal infection could also happen in these patients, such as candidal leukoplakia. We reported a 61 years old female patient who complained a painful lesion under her lower removable denture. Oral examination revealed white plaque that could not be rubbed over an ulcer on the lingual part of alveolar processes under the lower removable denture plate, and also an erythematous area on palatum durum above the upper full denture. The patient was suspected to have candidal leukoplakia on the lingual part of the mandible and denture stomatitis on the palate area. The treatment consisted of nystatin oral suspension, chlorhexidine solution, multivitamins, along with denture replacement and oral health education. The entire lesion resolved within 2 months therapy. Candidal infection treatment on denture patient needs not only medication or denture replacement, but also patient compliance to achieve maximal result.

  19. Social Justice Perceptions of Teacher Candidates

    Science.gov (United States)

    Turhan, Muhammed

    2010-01-01

    This study aims to determine the social justice perceptions of teacher candidates being trained in an education faculty. For this purpose, national and international literature was reviewed by the researcher and a 32-item questionnaire was developed and implemented on 237 senior year education faculty students. Data from the questionnaires were…

  20. Gallium-67 imaging in candidal esophagitis

    Energy Technology Data Exchange (ETDEWEB)

    Rundback, J.H.; Goldfarb, C.R.; Ongseng, F. (Beth Israel Medical Center, New York, NY (USA))

    1990-01-01

    Ga-67 scanning has been used to evaluate esophageal carcinoma. It has demonstrated candidal infection in other body sites and, in one previous case, in the esophagus. The authors present a case of diffuse esophageal uptake of Ga-67 in esophageal candidiasis.

  1. Gallium-67 imaging in candidal esophagitis

    International Nuclear Information System (INIS)

    Ga-67 scanning has been used to evaluate esophageal carcinoma. It has demonstrated candidal infection in other body sites and, in one previous case, in the esophagus. The authors present a case of diffuse esophageal uptake of Ga-67 in esophageal candidiasis

  2. Reason Analysis on Bursting Tube of High Temperature Boiler Tube of T92 Steel in Ultra Supercritical Unit%超超临界机组T92钢高温受热面管爆管原因分析

    Institute of Scientific and Technical Information of China (English)

    赵彦芬; 张路; 刘艳; 许万军

    2012-01-01

    The platen superheater tube failures of T92 steel has bursted in a ultra supercritical power plants. The bursting reason was analyzed by means of macroscopical inspection, chemical composition analysis, hardness testing, tensile strength testing, metallographie examination and so on. Results showed that the microstructure of the tube which didn't maintenance the typical lath martensite, the phase transformation at Ac~ ~Aca after short- term overheated. The strength decreased rapid distinctly, therefore the strength was not enough to endure the stress, finally the tube bursted. On the other hand, the relationship between the different microstructure and mechanical property was achieved by test in order to supervise for metal in thermal power plants for long term operation.%某电厂的后屏过热器T92钢管段发生爆管。通过宏观检验、化学成分分析、硬度检验、拉伸性能测试、金相检验以及相关计算分析了爆管的原因。结果表明:管段发生短时过热后,其显微组织为Acl-Ac3相变产物,失去了原典型的回火板条马氏体组织特征,材料强度大幅度降低,从而使得强度不足以抵抗管子的使用应力而发生爆管。另外,通过检验获得了不同状态下的组织与性能的对应关系,有利于长期运行中的金属监督检验。

  3. A Genome-wide Functional Characterization of Arabidopsis Regulatory Calcium Sensors in Pollen Tubes

    Institute of Scientific and Technical Information of China (English)

    Liming Zhou; Ying FU; Zhenbiao Yang

    2009-01-01

    Calcium, an ubiquitous second messenger, plays an essential and versatile role in cellular signaling. The diverse function of calcium signals is achieved by an excess of calcium sensors. Plants possess large numbers of calcium sensors, most of which have not been functionally characterized. To identify physiologically relevant calcium sensors in a specific cell type, we conducted a genome-wide functional survey in pollen tubes, for which spatiotemporal calcium signals are well-characterized and required for polarized tip growth. Pollen-specific members of calmodulin (CAM), CaM-like (CML), calcium-dependent protein kinase (CDPK) and calcineurin B-like protein (CBL) families were tagged with green fluorescence protein (GFP) and their localization patterns and overexpression phenotypes were characterized in tobacco pollen tubes. We found that several fusion proteins showed distinct overexpression phenotypes and subcellular localization patterns. CDPK24.GFP was localized to the vegetative nucleus and the generative cell/sperms. CDPK32-GFP caused severe growth depolarization. CBL2-GFP and CBL3-GFP exhibited dynamic patterns of subcellular localization, including several endomembrane compartments, the apical plasma membrane (PM), and cytoskeleton-like structures in pollen tubes. Their overexpression also inhibited pollen tube elongation and induced growth depolarization. These putative calcium sensors are excellent candidates for the calcium sensors responsible for the regulation of calcium homeostasis and calcium-dependent tip growth and growth oscillation in pollen tubes,

  4. Failure Analysis of Retired Steam Generator Tubings

    International Nuclear Information System (INIS)

    Since the first commercial operation of Kori-1 in 1978, 20 units of nuclear power plants are operated, and the it covers 40 % of total electricity in Korea as of 2008. A steam generator tube rupture incident occurred in the Ulchin unit 4 in 2002, which made the public sensitive to nuclear power plant. In order to keep the nuclear energy as a main energy source, the integrity of steam generator should be demonstrated. It is important to improve a flaw detection capability of the eddy current testing(ECT) in steam generator(SG) tubings in order to maintain the tube integrity. A quantified evaluation on the flaws on SG tubings, which is crucial for the tube integrity evaluation is not satisfactory. It is necessary to utilize the retired SG having various types of corrosion damages. In addition, an examination of pulled tube from Kori 1 retired steam generator will give us information about effectiveness of a remedial action(TiO2 addition) which was applied to mitigate ODSCC. A crack growth model is also needed to ensure a tube repair criteria for a next fuel cycle based on the ASME safety evaluation code, which has to meet a requirement that the flaws have to sustain under three times of normal operation pressure difference and 1.4 times of severe accident condition. In this project, hardware such as semi hot lab for pulled tube examination and modification of transportation cask for pulled tube and software such as procedure of transportation of radioactive steam generator tube and non-destructive and destructive examination of pulled tube were established. The non-destructive and destructive examination of pulled tubes from Kori 1 retired steam generator were performed in the semi hot lab. An effect of remedial actions applied to Kori 1 retired steam generator, PWSCC trend and bulk water chemistry and crevice chemistry in Kori 1 were evaluated. An electrochemical decontamination technology for pulled tube was developed to reduce a radiation exposure and enhance

  5. Failure analysis of retired steam generator tubings

    Energy Technology Data Exchange (ETDEWEB)

    Kim, Hong Pyo; Kim, J. S.; Hwang, S. S. and others

    2005-04-15

    Degradation of steam generator leads to forced outage and extension of outage, which causes increase in repair cost, cost of purchasing replacement power and radiation exposure of workers. Steam generator tube rupture incident occurred in Uljin 4 in 2002, which made public sensitive to nuclear power plant. To keep nuclear energy as a main energy source, integrity of steam generator should be demonstrated. Quantitative relationship between ECT(eddy current test) signal and crack size is needed in assesment of integrity of steam generator in pressurized water reactor. However, it is not fully established for application in industry. Retired steam generator of Kori 1 has many kinds of crack such as circumferential and axial primary water stress corrosion crack and outer diameter stress corrosion crack(ODSCC). So, it can be used in qualifying and improving ECT technology and in condition monitoring assesment for crack detected in ISI(in service inspection). In addition, examination of pulled tube of Kori 1 retired steam generator will give information about effectiveness of non welded sleeving technology which was employed to repair defect tubes and remedial action which was applied to mitigate ODSCC. In this project, hardware such as semi hot lab. for pulled tube examination and modification transportation cask for pulled tube and software such as procedure of transportation of radioactive steam generator tube and non-destructive and destructive examination of pulled tube were established. Non-destructive and destructive examination of pulled tubes from Kori 1 retired steam generator were performed in semi hot lab. Remedial actions applied to Kori 1 retired steam generator, PWSCC trend and bulk water chemistry and crevice chemistry in Kori 1 were evaluated. Electrochemical decontamination technology for pulled tube was developed to reduce radiation exposure and enhance effectiveness of pulled tube examination. Multiparameter algorithm developed at ANL, USA was

  6. Failure analysis of retired steam generator tubings

    International Nuclear Information System (INIS)

    Degradation of steam generator leads to forced outage and extension of outage, which causes increase in repair cost, cost of purchasing replacement power and radiation exposure of workers. Steam generator tube rupture incident occurred in Uljin 4 in 2002, which made public sensitive to nuclear power plant. To keep nuclear energy as a main energy source, integrity of steam generator should be demonstrated. Quantitative relationship between ECT(eddy current test) signal and crack size is needed in assesment of integrity of steam generator in pressurized water reactor. However, it is not fully established for application in industry. Retired steam generator of Kori 1 has many kinds of crack such as circumferential and axial primary water stress corrosion crack and outer diameter stress corrosion crack(ODSCC). So, it can be used in qualifying and improving ECT technology and in condition monitoring assesment for crack detected in ISI(in service inspection). In addition, examination of pulled tube of Kori 1 retired steam generator will give information about effectiveness of non welded sleeving technology which was employed to repair defect tubes and remedial action which was applied to mitigate ODSCC. In this project, hardware such as semi hot lab. for pulled tube examination and modification transportation cask for pulled tube and software such as procedure of transportation of radioactive steam generator tube and non-destructive and destructive examination of pulled tube were established. Non-destructive and destructive examination of pulled tubes from Kori 1 retired steam generator were performed in semi hot lab. Remedial actions applied to Kori 1 retired steam generator, PWSCC trend and bulk water chemistry and crevice chemistry in Kori 1 were evaluated. Electrochemical decontamination technology for pulled tube was developed to reduce radiation exposure and enhance effectiveness of pulled tube examination. Multiparameter algorithm developed at ANL, USA was

  7. Working session 2: Tubing inspection

    Energy Technology Data Exchange (ETDEWEB)

    Guerra, J. [Tecnatom, S.A. San Sebastian de los Reyes, Madrid (Spain); Tapping, R.L. [AECL, Chalk River, Ontario (Canada)

    1997-02-01

    This session was attended by delegates from 10 countries, and four papers were presented. A wide range of issues was tabled for discussion. Realizing that there was limited time available for more detailed discussion, three topics were chosen for the more detailed discussion: circumferential cracking, performance demonstration (to focus on POD and sizing), and limits of methods. Two other subsessions were organized: one dealt with some challenges related to the robustness of current inspection methods, especially with respect to leaving cracked tubes in service, and the other with developing a chart of current NDE technology with recommendations for future development. These three areas are summarized in turn, along with conclusions and/or recommendations. During the discussions there were four presentations. There were two (Canada, Japan) on eddy current probe developments, both of which addressed multiarray probes that would detect a range of flaws, one (Spain) on circumferential crack detection, and one (JRC, Petten) on the recent PISC III results.

  8. Reference factor F(CT)Q and X ray tube ionization yield R(TUBE)Q

    International Nuclear Information System (INIS)

    The operational facility procedures in diagnostic radiology standardization and calibration, through the relation between the X ray tube current and the ionization chamber current in a radiation quality Q, shown the reference factor F(CT)Q as the reality estimate to the X ray tube ionization yield, R(TUBE)Q . (author)

  9. Finite Element Analysis of the Elastic Plasticity of a Naval Boiler Superheater Expanded-joint%某舰用锅炉过热器胀接接头弹塑性有限元分析

    Institute of Scientific and Technical Information of China (English)

    周传月; 李桂英; 马云翔

    2001-01-01

    Through the use of a large-sized finite element general program ANSYS the contact analysis model of an expanded joint has been set up for the expanded joint structure of a naval boiler superheater and a finite element analysis of three-dimensional plasticity conducted. A study was performed of the effect of material properties and operating temperatures, etc on the residual contact pressure of the expanded joint. Also given in this paper are some proposals, which can serve as a guide for engineering design as well as for the prevention of failures and malfunctions.%针对某舰用锅炉过热器实际胀接结构,采用大型有限元通用程序ANSYS建立了胀接接触分析模型,进行了三维弹塑性有限元分析。研究了材料特性和工作温度等对胀接接头残余接触压力的影响,并提出一些对工程设计和排除故障具有指导作用的建议。

  10. 超临界锅炉顶棚过热器弯管断裂失效分析%Fracture Failure of Bent Pipe of Roof Superheater in Supercritical Boiler

    Institute of Scientific and Technical Information of China (English)

    郑相锋; 冯砚厅; 牛晓光; 徐雪霞

    2011-01-01

    采用宏观分析、力学分析、化学分析、金相检验及扫描电镜等方法对多次出现断裂的超临界锅炉顶棚过热器弯管(材质为12Cr1MoV)进行失效分析.结果表明,顶棚过热器弯管断裂属于脆性断裂,应力过大和弯管环境温度过低是造成泄漏的主要诱因.%Through the methods of microscope analysis, mechanical analysis, chemical analysis, metallographie examination and scanning electron microscope, the causes resulting in rupture of bent pipe (I2CMMoV) of roof superheater in msupercritical boiler were analyzed. The results indicate that the bent pipe fracture failure is brittle fracture The welding defects, excessive stress and lower working temperature in bending are the primar reasons for fracture failure.

  11. 高温纯铝低温高硅铝合金容体混合对组织的影响%Effects of Melt Mixture on Microstructure of Superheat Aluminum and Semi-Solid Hypereutectic Al-Si Alloy

    Institute of Scientific and Technical Information of China (English)

    罗松; 魏晓伟; 郑丽; 王小丽

    2013-01-01

    Through mixing the superheat aluminum and semi-solid hypereutectic Al-Si alloy melt, the changes in solidification microstructure of alloy were studied. The results show that the alloy obtained by the first method has the characteristics of both hypoeutectic and hypereutectic Al-Si alloy, and the apparent refinement of primary silicon occurs. The alloys obtained by the latter two methods have only structural characteristics of hypereutectic Al-Si alloy, and primary silicon refinement effect was not significant%通过过热纯铝液与半固态过共晶铝硅合金熔体混合,研究了凝固组织的变化,并对比了750℃熔炼浇注与常规熔体混合两种方法对组织的影响.结果表明,前者所得的合金凝固组织兼具亚共晶和过共晶铝硅合金组织特征,并且能很好地细化初生Si相.后两种方法所得合金只具有一般过共晶铝硅合金组织特征,且对初生Si相的细化效果不显著.

  12. 22 CFR 11.8 - Travel expenses of candidates.

    Science.gov (United States)

    2010-04-01

    ... 22 Foreign Relations 1 2010-04-01 2010-04-01 false Travel expenses of candidates. 11.8 Section 11... Travel expenses of candidates. The travel and other personal expenses of candidates incurred in... Department may issue round-trip invitational travel orders to bring candidates to Washington at...

  13. Candidate marketing takes the guessing game out of choosing employers.

    Science.gov (United States)

    Russell, Judith; Havel, Stacey

    2010-01-01

    Candidate marketing builds a foundation for relationships between employers and potential employees. Additionally, candidate marketing differentiates organizations in the marketplace. Organizations using candidate marketing to communicate the employer brand can expect a higher quality of candidates, and new employees are better prepared for the work environment and culture. Today, organizations can use a variety of integrated tools and techniques to communicate and build relationships with candidates. Candidate marketing demonstrates an organization's willingness towards transparency, and ability to invite open conversations between candidates and members of the organizations. PMID:20672542

  14. Confined Tube Crimp Using Portable Hand Tools

    Energy Technology Data Exchange (ETDEWEB)

    Reynolds, Joseph James [Los Alamos National Laboratory; Pereyra, R. A. [LANL Retired; Archuleta, Jeffrey Christopher [Los Alamos National Laboratory; Martinez, Isaac P. [Los Alamos National Laboratory; Nelson, A. M. [MST-16 Summer Student (2007); Allen, Ronald Scott [Los Alamos National Laboratory; Page, R. L. [LANL Retired; Freer, Jerry Eugene [Los Alamos National Laboratory; Dozhier, Nathan Gus [Los Alamos National Laboratory

    2016-04-04

    The Lawrence Radiation Laboratory developed handheld tools that crimp a 1/16 inch OD tube, forming a leak tight seal1 (see Figure 1). The leak tight seal forms by confining the 1/16 inch OD tubing inside a die while applying crimp pressure. Under confined pressure, the tube walls weld at the crimp. The purpose of this study was to determine conditions for fabricating a leak tight tube weld. The equipment was used on a trial-and-error basis, changing the conditions after each attempt until successful welds were fabricated. To better confine the tube, the die faces were polished. Polishing removed a few thousandths of an inch from the die face, resulting in a tighter grip on the tubing wall. Using detergent in an ultrasonic bath, the tubing was cleaned. Also, the time under crimp pressure was increased to 30 seconds. With these modifications, acceptable cold welds were fabricated. After setting the conditions for an acceptable cold weld, the tube was TIG welded across the crimped face.

  15. A. P. S. ELECTRO-TUBE EVALUATION

    Science.gov (United States)

    The report gives results of an evaluation of an Air Pollution Systems (APS) Inc. Electro-Tube, a wet electrostatic precipitator. Fine particle collection efficiency as a function of particle size was computed from data taken on the Electro-Tube. It was operated at gas flow rates ...

  16. Coated tube for immunochemical and enzymatic assays

    International Nuclear Information System (INIS)

    Containers such as test tubes suitable for use in solid phase immunochemical, enzymatical and particularly radioimmunoassay procedures are described. The lower part of the tube is a polymer, coated with an inert protein to which a biologically active substance eg an antibody to triiodothyronine, thyroxine or digoxin, is attached. (U.K.)

  17. Swelling of spent fuel storage tubes

    International Nuclear Information System (INIS)

    Unexpected swelling phenomena have been reported in the storage racks of the spent fuel pool at several nuclear power plants. Experimental and analytical studies have been carried out in order to identify the governing mechanism and to analyze the interaction of the storage tube and the spent fuel element housed in the tube. (author). 2 refs., 7 figs

  18. Places to Go: YouTube

    Science.gov (United States)

    Downes, Stephen

    2008-01-01

    Founded in 2005 by three former PayPal employees, YouTube has revolutionized the Internet, marking a change from the static Internet to the dynamic Internet. In this edition of Places to Go, Stephen Downes discusses how the rise of a ubiquitous media format--Flash video--has made YouTube's success possible and argues that Flash video has important…

  19. Broadcast yourself on YouTube - really?

    NARCIS (Netherlands)

    G. Kruitbosch; F. Nack

    2008-01-01

    One essential reason for people to publish on the web is to express themselves freely. YouTube facilitates this self-expression by allowing users to upload video content they generated. This paper investigates to what extent the videos on YouTube are self-generated content, instead of amalgamated co

  20. Teaching Shakespeare with YouTube

    Science.gov (United States)

    Desmet, Christy

    2009-01-01

    YouTube, the video sharing website that allows viewers to upload video content ranging from cute dog tricks to rare rock videos, also supports a lively community devoted to the performance of Shakespeare and Shakespearean adaptations. YouTube is also a popular site for student producers of Shakespeare performances, parodies, and other artistic…