WorldWideScience

Sample records for generator tube degradation

  1. Rupture pressure of wear degraded alloy 600 steam generator tubings

    Science.gov (United States)

    Hwang, Seong Sik; Namgung, Chan; Jung, Man Kyo; Kim, Hong Pyo; Kim, Joung Soo

    2008-02-01

    Fretting/wear degradation at the tube support in the U-bend region of a steam generator (SG) of a pressurized water reactor (PWR) has been reported. Simulated fretted flaws were machined on SG tubes of 195 mm in length. A pressure test was carried out with the tubes at room temperature by using a high pressure test facility which consisted of a water pressurizing pump, a test specimen section and a control unit. Water leak rates just after a ligament rupture or a burst were measured. Tubes degraded by up to 70% of the tube wall thickness (TW) showed a high safety margin in terms of the burst pressure during normal operating conditions. Tubes degraded by up to 50% of the TW did not show burst. Burst pressure depended on the defect depths rather than on the wrap angles. The tube with a wrap angle of 0° showed a fish mouth fracture, whereas the tube with a 45° wrap angle showed a three way fracture.

  2. Health and safety impact of steam generator tube degradation

    Energy Technology Data Exchange (ETDEWEB)

    Marston T. [PLG, Inc., Newport Beach, CA (United States)

    1997-02-01

    In this paper the author addresses the problems inherent in evaluating the safety of steam generators with respect to tube rupture as part of a probabilistic safety analysis (PSA) of a reactor plant. He reviews the history of PSA as applied to reactors, and then looks at tube rupture histories as a start toward establishing event frequencies. He considers tube ruptures from the aspect of being an initiating event to being a conditional event to some other event, and then the question of performance of the steam generator in the face of a severe accident in the reactor.

  3. French steam generator tubes: an overview of degradations

    Energy Technology Data Exchange (ETDEWEB)

    Buisine, D.; Bouvier, O. de; Rupa, N.; Thebault, Y.; Barbe, V. [EDF-CEIDRE Nuclear Engineering Division (France); Pitner, P. [EDF-UNIE Generation Nuclear Operation Division (France)

    2011-07-01

    The various damages (corrosion, fatigue cracks, wear, ...) observed on steam generator (SG) tubes are presented here as well as the techniques used to characterize these damages. The SG are equipped with tubes of 3 materials: 600 MA, 600 TT and 690 TT. Concerning PWSCC of 600 MA and 600 TT tubes, beyond the damages usually observed (corrosion in expansion transition zone and in 600 MA tubes small radius U-bend zone), a new event is to be noted: the phenomenon of denting (presumably induced by the deposit of sludge on the tubesheet) has induced circumferential cracking of the tube expansion transition zone. Concerning ODSCC of 600 MA tubes, beyond the classically observed damages (IGA and IGSCC in expansion transition zone and in TSP crevice), a new event is to be noted: the occurrence of circumferential cracks in tube- TSP crevice. Concerning fatigue cracking, two events have to be noted at upper TSP level in Cruas 1 and Cruas 4 units and in Fessenheim 2 unit. The first (Cruas) was due to the blockage in the broached hole tube support plate which can create critical velocity ratios for some tubes and the second (Fessenheim) to high-cycle fatigue. Concerning wear damage, beyond what is usually observed in the U-bend zone facing the anti-vibration bars (AVB), a new event is to be noted: a wear at TSP level is observed on SG equipped with an economizer, the wear indications being located at TSP 7 and 8 level, on outer tubes close to the central lane. The number of tubes plugged for ODSCC has declined due to the progressive replacement of SG with Alloy 600 MA tubing. Starting in 2004, the increasing plugging of 690 tubing is mainly due to AVB wear. Since 2006, extensive preventive plugging campaigns for tubes at risk of high-cycle fatigue at the upper support plate are performed. Risk of high-cycle fatigue has consequently become the dominant mechanism inducing plugging. PWSCC is the second dominant mechanism which affects 600 MA and 600 TT tube bundles: extensive

  4. Status of the steam generator tube circumferential ODSCC degradation experienced at the Doel 4 plant

    Energy Technology Data Exchange (ETDEWEB)

    Roussel, G. [AIB-Vincotte Nuclear, Brussels (Belgium)

    1997-02-01

    Since the 1991 outage, the Doel Unit 4 nuclear power plant is known to be affected by circumferential outside diameter intergranular stress corrosion cracking at the hot leg tube expansion transition. Extensive non destructive examination inspections have shown the number of tubes affected by this problem as well as the size of the cracks to have been increasing for the three cycles up to 1993. As a result of the high percentage of tubes found non acceptable for continued service after the 1993 in-service inspection, about 1,700 mechanical sleeves were installed in the steam generators. During the 1994 outage, all the tubes sleeved during the 1993 outage were considered as potentially cracked to some extent at the upper hydraulic transition and were therefore not acceptable for continued service. They were subsequently repaired by laser welding. Furthermore all the tubes not sleeved during the 1993 outage were considered as not acceptable for continued service and were repaired by installing laser welded sleeves. During the 1995 outage, some unexpected degradation phenomena were evidenced in the sleeved tubes. This paper summarizes the status of the circumferential ODSCC experienced in the SG tubes of the Doel 4 plant as well as the other connected degradation phenomena.

  5. Selection of statistical distributions for prediction of steam generator tube degradation

    Energy Technology Data Exchange (ETDEWEB)

    Stavropoulos, K.D.; Gorman, J.A. [Dominion Engr., Inc., McLean, VA (United States); Staehle, R.W. [Univ. of Minnesota, Minneapolis, MN (United States); Welty, C.S. Jr. [Electric Power Research Institute, Palo Alto, CA (United States)

    1992-12-31

    This paper presents the first part of a project directed at developing methods for characterizing and predicting the progression of degradation of PWR steam generator tubes. This first part covers the evaluation of statistical distributions for use in such analyses. The data used in the evaluation of statistical distributions included data for primary water stress corrosion cracking (PWSCC) at roll transitions and U-bends, and intergranular attack/stress corrosion cracking (IGA/SCC) at tube sheet and tube support plate crevices. Laboratory data for PWSCC of reverse U-bends were also used. The review of statistical distributions indicated that the Weibull distribution provides an easy to use and effective method. Another statistical function, the log-normal, was found to provide essentially equivalent results. Two parameter fits, without an initiation time, were found to provide the most reliable predictions.

  6. Steam generator tube support plate degradation in French plants: maintenance strategy

    Energy Technology Data Exchange (ETDEWEB)

    Gauchet, J.-P. [EDF, NPP Operations/Maintenance Dept. (France); Gillet, N. [FRAMATOME, Steam Generator Dept. (France); Stindel, M. [EDF, Central Labs. (France)

    1998-07-01

    This paper reports on the degradations of Steam Generator (SG) Tube Support Plates (TSPs) observed in French plants and the maintenance strategy adopted to continue operating the plant without any decrease of the required safety level. Only drilled carbon steel TSPs of early SGs are affected. Except the particular damage of the TSP8 of FESSENHEIM 2 caused by chemical cleaning procedures implemented in 1992, two main problems were observed almost exclusively on the upper TSP: Ligaments ruptured near the aseismic block located at 215 degrees. This degradation is perfectly detectable by bobbin coil inspection. It occurs very early in the life of the SG as can be seen from the records of previous inspections and no evolution of the signals was observed. This damage can be detected for 51M model SGs on several sites; Wastage of the ligaments resulting in enlargement of flow holes with in some cases complete consumption of a ligament. This damage was only observed for SGs of at GRAVELINES. This damage evolved cycle after cycle. Detailed studies were performed to analyze tubing behavior when a tube is not supported by the upper TSP because of missing ligaments. These studies evaluated the risk of vibratory instability, the behavior of both the TSP and the tubing in case of a seismic event or a LOCA and finally the behavior of the TSP in case of a Steam Line Break. Concerning vibratory instability it was possible to define zones where stability could not be demonstrated. Dampine, cables and sentinel plugs were then used when necessary to eliminate the risk of Steam Generator Tube Rupture (SGTR). For accidental conditions, it could be shown that no unacceptable damage occurs and that the core cooling function of the SG is always maintained if some tubes are plugged. From this analysis, It was possible to define the inspection programs for the different plants taking into account the specific situation of each plant regarding the damages detected. These programs include

  7. On the probability of exceeding allowable leak rates through degraded steam generator tubes

    Energy Technology Data Exchange (ETDEWEB)

    Cizelj, L.; Sorsek, I. [Jozef Stefan Institute, Ljubljana (Slovenia); Riesch-Oppermann, H. [Forschungszentrum Karlsruhe (Germany)

    1997-02-01

    This paper discusses some possible ways of predicting the behavior of the total leak rate through the damaged steam generator tubes. This failure mode is of special concern in cases where most through-wall defects may remain In operation. A particular example is the application of alternate (bobbin coil voltage) plugging criterion to Outside Diameter Stress Corrosion Cracking at the tube support plate intersections. It is the authors aim to discuss some possible modeling options that could be applied to solve the problem formulated as: Estimate the probability that the sum of all individual leak rates through degraded tubes exceeds the predefined acceptable value. The probabilistic approach is of course aiming at reliable and computationaly bearable estimate of the failure probability. A closed form solution is given for a special case of exponentially distributed individual leak rates. Also, some possibilities for the use of computationaly efficient First and Second Order Reliability Methods (FORM and SORM) are discussed. The first numerical example compares the results of approximate methods with closed form results. SORM in particular shows acceptable agreement. The second numerical example considers a realistic case of NPP in Krsko, Slovenia.

  8. 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.

  9. 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.

  10. Studies of the steam generator degraded tubes behavior on BRUTUS test loop

    Energy Technology Data Exchange (ETDEWEB)

    Chedeau, C.; Rassineux, B. [EDF/DER/MTC, Moret Sur Loing (France); Flesch, B. [EDF/EPN/DMAINT, Paris (France)] [and others

    1997-04-01

    Studies for the evaluation of steam generator tube bundle cracks in PWR power plants are described. Global tests of crack leak rates and numerical calculations of crack opening area are discussed in some detail. A brief overview of thermohydraulic studies and the development of a mechanical probabilistic design code is also given. The COMPROMIS computer code was used in the studies to quantify the influence of in-service inspections and maintenance work on the risk of a steam generator tube rupture.

  11. 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.

  12. Steam generator tube degradation at the Doel 4 plant influence on plant operation and safety

    Energy Technology Data Exchange (ETDEWEB)

    Scheveneels, G. [AIB-Vincotte Nuclear, Brussels (Belgium)

    1997-02-01

    The steam generator tubes of Doel 4 are affected by a multitude of corrosion phenomena. Some of them have been very difficult to manage because of their extremely fast evolution, non linear evolution behavior or difficult detectability and/or measurability. The exceptional corrosion behavior of the steam generator tubes has had its drawbacks on plant operation and safety. Extensive inspection and repair campaigns have been necessary and have largely increased outage times and radiation exposure to personnel. Although considerable effort was invested by the utility to control corrosion problems, non anticipated phenomena and/or evolution have jeopardized plant safety. The extensive plugging and repairs performed on the steam generators have necessitated continual review of the design basis safety studies and the adaptation of the protection system setpoints. The large asymmetric plugging has further complicated these reviews. During the years many preventive and recently also defence measures have been implemented by the utility to manage corrosion and to decrease the probability and consequences of single or multiple tube rupture. The present state of the Doel 4 steam generators remains troublesome and further examinations are performed to evaluate if continued operation until June `96, when the steam generators will be replaced, is justified.

  13. 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.

  14. 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.)

  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. 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

  17. Automated Diagnosis and Classification of Steam Generator Tube Defects

    Energy Technology Data Exchange (ETDEWEB)

    Dr. Gabe V. Garcia

    2004-10-01

    A major cause of failure in nuclear steam generators is tube degradation. Tube defects are divided into seven categories, one of which is intergranular attack/stress corrosion cracking (IGA/SCC). Defects of this type usually begin on the outer surface of the tubes and propagate both inward and laterally. In many cases these defects occur at or near the tube support plates. Several different methods exist for the nondestructive evaluation of nuclear steam generator tubes for defect characterization.

  18. A tube-in-tube thermophotovoltaic generator

    Energy Technology Data Exchange (ETDEWEB)

    Ashcroft, J.; Campbell, B.; Depoy, D.

    1996-12-31

    A thermophotovoltaic device includes at least one thermal radiator tube, a cooling tube concentrically disposed within each thermal radiator tube and an array of thermophotovoltaic cells disposed on the exterior surface of the cooling tube. A shell having a first end and a second end surrounds the thermal radiator tube. Inner and outer tubesheets, each having an aperture corresponding to each cooling tube, are located at each end of the shell. The thermal radiator tube extends within the shell between the inner tubesheets. The cooling tube extends within the shell through the corresponding apertures of the two inner tubesheets to the corresponding apertures of the two outer tubesheets. A plurality of the thermal radiator tubes can be arranged in a staggered or an in-line configuration within the shell.

  19. Steam generator tube integrity flaw acceptance criteria

    Energy Technology Data Exchange (ETDEWEB)

    Cochet, B. [FRAMATOME, Paris la Defense (France)

    1997-02-01

    The author discusses the establishment of a flaw acceptance criteria with respect to flaws in steam generator tubing. The problem is complicated because different countries take different approaches to the problem. The objectives in general are grouped in three broad areas: to avoid the unscheduled shutdown of the reactor during normal operation; to avoid tube bursts; to avoid excessive leak rates in the event of an accidental overpressure event. For each degradation mechanism in the tubes it is necessary to know answers to an array of questions, including: how well does NDT testing perform against this problem; how rapidly does such degradation develop; how well is this degradation mechanism understood. Based on the above information it is then possible to come up with a policy to look at flaw acceptance. Part of this criteria is a schedule for the frequency of in-service inspection and also a policy for when to plug flawed tubes. The author goes into a broad discussion of each of these points in his paper.

  20. Status of steam generator tubing integrity at Jaslovske Bohunice NPP

    Energy Technology Data Exchange (ETDEWEB)

    Cepcek, S. [Nuclear Regulatory Authority of the Slovak Republic, Trnava (Slovakia)

    1997-02-01

    Steam generator represents one of the most important component of nuclear power plants. Especially, loss of tubing integrity of steam generators can lead to the primary coolant leak to secondary circuit and in worse cases to the unit shut down or to the PTS events occurrence. Therefore, to ensure the steam generator tubing integrity and the current knowledge about tube degradation propagation and development is of the highest importance. In this paper the present status of steam generator tubing integrity in operated NPP in Slovak Republic is presented.

  1. Steam generator tube inspection in Japan

    Energy Technology Data Exchange (ETDEWEB)

    Fukui, Shigetaka [Japan Power Engineering and Inspection Corp., Tokyo (Japan)

    1997-02-01

    Steam generator tube inspection was first carried out in 1971 at Mihama Unit-1 that is first PWR plant in Japan, when the plant was brought into the first annual inspection. At that time, inspection was made on sampling basis, and only bobbin coil probe was used. After experiencing various kinds of tube degradations, inspection method was changed from sampling to all number of tubes, and various kinds of probes were used to get higher detectability of flaw. At present, it is required that all the tubes shall be inspected in their full length at each annual inspection using standard bobbin coil probe, and some special probes for certain plants that have susceptibility of occurrence of flaw. Sleeve repaired portion is included in this inspection. As a result of analyses of eddy current testing data, all indications that have been evaluated to be 20% wall thickness or deeper shall be repaired by either plugging or sleeving, where flaw morphology is to be a wastage or wear. Other types of flaw such as IGA/SCC are not allowed to be left inservice when those indications are detected. These inspections are performed according to inspection procedures that are approved by regulatory authority. Actual inspections are witnessed by the Japan Power engineering and inspection corporation (JAPEIC)`s inspectors during data acquisition and analysis, and they issue inspection report to authority for review and approval. It is achieved high safety performance of steam generator through this method of inspections, however. some tube leakage problems were experienced in the past. To prevent recurrence of such events, government is conducting development and verification test program for new eddy current testing technology.

  2. Steam generator tubing NDE performance

    Energy Technology Data Exchange (ETDEWEB)

    Henry, G. [Electric Power Research Institute, Charlotte, NC (United States); Welty, C.S. Jr. [Electric Power Research Institute, Palo Alto, CA (United States)

    1997-02-01

    Steam generator (SG) non-destructive examination (NDE) is a fundamental element in the broader SG in-service inspection (ISI) process, a cornerstone in the management of PWR steam generators. Based on objective performance measures (tube leak forced outages and SG-related capacity factor loss), ISI performance has shown a continually improving trend over the years. Performance of the NDE element is a function of the fundamental capability of the technique, and the ability of the analysis portion of the process in field implementation of the technique. The technology continues to improve in several areas, e.g. system sensitivity, data collection rates, probe/coil design, and data analysis software. With these improvements comes the attendant requirement for qualification of the technique on the damage form(s) to which it will be applied, and for training and qualification of the data analysis element of the ISI process on the field implementation of the technique. The introduction of data transfer via fiber optic line allows for remote data acquisition and analysis, thus improving the efficiency of analysis for a limited pool of data analysts. This paper provides an overview of the current status of SG NDE, and identifies several important issues to be addressed.

  3. Advanced Eddy current NDE steam generator tubing.

    Energy Technology Data Exchange (ETDEWEB)

    Bakhtiari, S.

    1999-03-29

    As part of a multifaceted project on steam generator integrity funded by the U.S. Nuclear Regulatory Commission, Argonne National Laboratory is carrying out research on the reliability of nondestructive evaluation (NDE). A particular area of interest is the impact of advanced eddy current (EC) NDE technology. This paper presents an overview of work that supports this effort in the areas of numerical electromagnetic (EM) modeling, data analysis, signal processing, and visualization of EC inspection results. Finite-element modeling has been utilized to study conventional and emerging EC probe designs. This research is aimed at determining probe responses to flaw morphologies of current interest. Application of signal processing and automated data analysis algorithms has also been addressed. Efforts have focused on assessment of frequency and spatial domain filters and implementation of more effective data analysis and display methods. Data analysis studies have dealt with implementation of linear and nonlinear multivariate models to relate EC inspection parameters to steam generator tubing defect size and structural integrity. Various signal enhancement and visualization schemes are also being evaluated and will serve as integral parts of computer-aided data analysis algorithms. Results from this research will ultimately be substantiated through testing on laboratory-grown and in-service-degraded tubes.

  4. A Flue Gas Tube for Thermoelectric Generator

    DEFF Research Database (Denmark)

    2013-01-01

    The invention relates to a flue gas tube (FGT) (1) for generation of thermoelectric power having thermoelectric elements (8) that are integrated in the tube. The FTG may be used in combined heat and power (CHP) system (13) to produce directly electricity from waste heat from, e.g. a biomass boiler...

  5. Eddy Current Signature Classification of Steam Generator Tube Defects Using A Learning Vector Quantization Neural Network

    Energy Technology Data Exchange (ETDEWEB)

    Gabe V. Garcia

    2005-01-03

    A major cause of failure in nuclear steam generators is degradation of their tubes. Although seven primary defect categories exist, one of the principal causes of tube failure is intergranular attack/stress corrosion cracking (IGA/SCC). This type of defect usually begins on the secondary side surface of the tubes and propagates both inwards and laterally. In many cases this defect is found at or near the tube support plates.

  6. Overview of steam generator tube-inspection technology

    Energy Technology Data Exchange (ETDEWEB)

    Obrutsky, L.; Renaud, J.; Lakhan, R., E-mail: obrutskl@aecl.ca, E-mail: renaudj@aecl.ca, E-mail: lakhanr@aecl.ca [Atomic Energy of Canada Limited, Chalk River, Ontario (Canada)

    2014-03-15

    Degradation of steam generator (SG) tubing due to both mechanical and corrosion modes has resulted in extensive repairs and replacement of SGs around the world. The variety of degradation modes challenges the integrity of SG tubing and, therefore, the stations' reliability. Inspection and monitoring aimed at timely detection and characterization of the degradation is a key element for ensuring tube integrity. Up to the early-70's, the in-service inspection of SG tubing was carried out using single-frequency eddy current testing (ET) bobbin coils, which were adequate for the detection of volumetric degradation. By the mid-80's, additional modes of degradation such as pitting, intergranular attack, and axial and circumferential inside or outside diameter stress corrosion cracking had to be addressed. The need for timely, fast detection and characterization of these diverse modes of degradation motivated the development in the 90's of inspection systems based on advanced probe technology coupled with versatile instruments operated by fast computers and remote communication systems. SG inspection systems have progressed in the new millennium to a much higher level of automation, efficiency and reliability. Also, the role of Non Destructive Evaluation (NDE) has evolved from simple detection tools to diagnostic tools that provide input into integrity assessment decisions, fitness-far-service and operational assessments. This new role was motivated by tighter regulatory requirements to assure the safety of the public and the environment, better SG life management strategies and often self-imposed regulations. It led to the development of advanced probe technologies, more reliable and versatile instruments and robotics, better training and qualification of personnel and better data management and analysis systems. This paper provides a brief historical perspective regarding the evolution of SG inspections and analyzes the motivations behind that

  7. Data analysis for steam generator tubing samples

    Energy Technology Data Exchange (ETDEWEB)

    Dodd, C.V.

    1996-07-01

    The objective of the Improved Eddy-Current ISI for Steam Generators program is to upgrade and validate eddy-current inspections, including probes, instrumentation, and data processing techniques for inservice inspection of new, used, and repaired steam generator tubes; to improve defect detection, classification and characterization as affected by diameter and thickness variations, denting, probe wobble, tube sheet, tube supports, copper and sludge deposits, even when defect types and other variables occur in combination; to transfer this advanced technology to NRC`s mobile NDE laboratory and staff. This report provides a description of the application of advanced eddy-current neural network analysis methods for the detection and evaluation of common steam generator tubing flaws including axial and circumferential outer-diameter stress-corrosion cracking and intergranular attack. The report describes the training of the neural networks on tubing samples with known defects and the subsequent evaluation results for unknown samples. Evaluations were done in the presence of artifacts. Computer programs are given in the appendix.

  8. Flow induced pulsations generated in corrugated tubes

    NARCIS (Netherlands)

    Belfroid, S.P.C.; Swindell, R.; Tummers, R.

    2008-01-01

    Corrugated tubes can produce a tonal noise when used for gas transport, for instance in the case of flexible risers. The whistling sound is generated by shear layer instability due to the boundary layer separation at each corrugation. This whistling is examined by investigating the frequency, amplit

  9. Steam Generator tube integrity -- US Nuclear Regulatory Commission perspective

    Energy Technology Data Exchange (ETDEWEB)

    Murphy, E.L.; Sullivan, E.J.

    1997-02-01

    In the US, the current regulatory framework was developed in the 1970s when general wall thinning was the dominant degradation mechanism; and, as a result of changes in the forms of degradation being observed and improvements in inspection and tube repair technology, the regulatory framework needs to be updated. Operating experience indicates that the current U.S. requirements should be more stringent in some areas, while in other areas they are overly conservative. To date, this situation has been dealt with on a plant-specific basis in the US. However, the NRC staff is now developing a proposed steam generator rule as a generic framework for ensuring that the steam generator tubes are capable of performing their intended safety functions. This paper discusses the current U.S. regulatory framework for assuring steam generator (SG) tube integrity, the need to update this regulatory framework, the objectives of the new proposed rule, the US Nuclear Regulatory Commission (NRC) regulatory guide (RG) that will accompany the rule, how risk considerations affect the development of the new rule, and some outstanding issues relating to the rule that the NRC is still dealing with.

  10. Lessons learned from tubes pulled from French steam generators

    Energy Technology Data Exchange (ETDEWEB)

    Berge, Ph.; Boursier, J.M.; Dallery, D.; De Keroulas, F.; Rouillon, Y. [Electricite de France, Generating and Transmission Div. (France)

    1998-07-01

    Since 1981, the Chinon Hot Laboratory has completed more than 380 metallurgical examinations of pulled French steam generator tubes. Electricite de France decided to perform such investigations from the very outset of the French nuclear program, in order to contribute to nuclear power plant safety. The main reasons for withdrawing tubes are to evaluate the degradation, to validate non destructive examination (NDE) techniques, to gain a better understanding of cracking phenomena, and to ensure that the criteria on which plugging operations are based remain conservative. Considerable experience has been accumulated in the field of primary water stress corrosion cracking (PWSCC), OD (secondary) side corrosion, leak and burst tests, and various tube plugging techniques. This paper focuses on the PWSCC phenomenon and on the secondary side corrosion process, and in particular, attempts to correlate French data from pulled tubes with the results of fundamental R and D studies. Finally, within the framework of the Nuclear Power Plant Safety and Maintenance Policy, all these results are discussed in terms of optimization of the field inspection of tube bundles and plugging criteria. (author)

  11. The relative impact of sizing errors on steam generator tube failure probability

    Energy Technology Data Exchange (ETDEWEB)

    Cizelj, L.; Dvorsek, T. [Jozef Stefan Inst., Ljubljana (Slovenia)

    1998-07-01

    The Outside Diameter Stress Corrosion Cracking (ODSCC) at tube support plates is currently the major degradation mechanism affecting the steam generator tubes made of Inconel 600. This caused development and licensing of degradation specific maintenance approaches, which addressed two main failure modes of the degraded piping: tube rupture; and excessive leakage through degraded tubes. A methodology aiming at assessing the efficiency of a given set of possible maintenance approaches has already been proposed by the authors. It pointed out better performance of the degradation specific over generic approaches in (1) lower probability of single and multiple steam generator tube rupture (SGTR), (2) lower estimated accidental leak rates and (3) less tubes plugged. A sensitivity analysis was also performed pointing out the relative contributions of uncertain input parameters to the tube rupture probabilities. The dominant contribution was assigned to the uncertainties inherent to the regression models used to correlate the defect size and tube burst pressure. The uncertainties, which can be estimated from the in-service inspections, are further analysed in this paper. The defect growth was found to have significant and to some extent unrealistic impact on the probability of single tube rupture. Since the defect growth estimates were based on the past inspection records they strongly depend on the sizing errors. Therefore, an attempt was made to filter out the sizing errors and to arrive at more realistic estimates of the defect growth. The impact of different assumptions regarding sizing errors on the tube rupture probability was studied using a realistic numerical example. The data used is obtained from a series of inspection results from Krsko NPP with 2 Westinghouse D-4 steam generators. The results obtained are considered useful in safety assessment and maintenance of affected steam generators. (author)

  12. Recent integrity program for WWER steam generator tubes

    Energy Technology Data Exchange (ETDEWEB)

    Wilam, M.; Papp, L.

    1994-12-31

    Considerable effort was given to NPP steam generator (SG) tubes integrity investigations during last years. These evaluations were focused on vertical SG tubing, i.e. on INCONEL tubes with geometry typical for this type of SG. The Steam Generator Tubes Integrity Program was conducted in VITKOVICE, R and D using WWER SG tubes. These tubes are made of 08Ch18N10T type stainless steel that corresponds to AISI 321 grade. The outer diameter of WWER tubes is 16 mm and the wall thickness is 1.5 mm.

  13. Characteristics of U-tube assembly design for CANDU 6 type steam generators

    Energy Technology Data Exchange (ETDEWEB)

    Park, Jun Su; Jeong, Seung Ha [Korea Atomic Energy Research Institute, Taejon (Korea, Republic of)

    1996-06-01

    Since the first operation of nuclear steam generator early 1960s, its performance requirements have been met but the steam generator problems have been met but the steam generator problems have been major cause of reducing the operational reliability, plant safety and availability. U-tube assembly of steam generator forms the primary system pressure boundary of the plant and have experienced several types of tube degradation problems. Tube failure and leakage resulting from the degradation will cause radioactive contamination of secondary system by the primary coolant, and this may lead to unplanned plant outages and costly repair operations such as tube plugging or steam generator replacement. For the case of steam generators for heavy water reactors, e.g. Wolsong 2, 3, and 4 NPP, a high cost of heavy water will be imposed additionally. During the plant operation, steam generator tubes can potentially be subject to adverse environmental conditions which will cause damages to U-tube assembly. Types of the damage depend upon the combined effects of design factors, materials and chemical environment of steam generator, and they are the pure water stress corrosion cracking, intergranular attack, pitting, wastage, denting, fretting and fatigue, etc. In this report, a comprehensive review of major design factors of recirculating steam generators has been performed against the potential tube damages. Then the design characteristics of CANDU-type Wolsong steam generator were investigated in detail, including tube material, thermalhydraulic aspects, tube-to-tubesheet joint, tube supports, water chemistry and sludge management. 9 tabs., 18 figs., 38 refs. (Author) .new.

  14. 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.

  15. Evaluation on mechanical and corrosion properties of steam generator tubing materials

    Energy Technology Data Exchange (ETDEWEB)

    Kim, In Sup; Lee, Byong Whi; Lee, Sang Kyu; Lee, Young Ho; Kim, Jun Whan; Lee, Ju Seok; Kwon, Hyuk Sang; Kim, Su Jung [Korea Advanced Institute of Science and Technology, Taejon (Korea, Republic of)

    1998-06-15

    Steam generator is one of the major components of nuclear reactor pressure boundary. It's main function os transferring heat which generated in the reactor to turbine generator through steam generator tube. In these days, steam generator tubing materials of operating plant are used Inconel 600 alloys. But according to the operation time, there are many degradation phenomena which included mechanical damage due to flow induced vibration and corrosion damage due to PWSCC, IGA/SCC and pitting etc. Recently Inconel 690 alloys are selected as new and replacement steam generator tubes for domestic nuclear power plant. But there are few study about mechanical and corrosion properties of Inconel 600 and 690. The objectives of this study is to evaluate and compare mechanical and corrosion propertied of steam generator tube materials.

  16. SG (steam generator) tube repair by explosive welding

    Energy Technology Data Exchange (ETDEWEB)

    Helmley, J.M. (Babcock and Wilcox Co., Lynchburg, VA (United States))

    1993-03-01

    Traditional joining techniques have limitations for bonding the ends of repair sleeves inside PWR cracked steam generator tubes. Explosive (kinetic) welding has been used as a successful alternative in over 5000 defective tubes. (author).

  17. Power Generation Capabilities of Tie Tube Assemblies

    Science.gov (United States)

    Gunn, Stanley V.; Hedstrom, James; Hundal, Rolv

    1994-07-01

    Second generation nuclear thermal rocket engine designs, employing solid core reactors and expander engine cycles, generally rely on some form of nuclear-driven heater to supply the major portion of thermal energy required to preheat the turbine-drive gases. If adequate heat transfer occurs, not only will efficiency-enhancing turbine-inlet temperatures be realized, but sufficient energy will be available to enable engine operation at chamber pressures ranging to at least 2,000 psia. For the case of reactor cores employing prismatic fuel elements, the utilization of tie tube assemblies, as first employed in the core-support subsystem of the Phoebus II reactor, can provide the basis of an array of propellant (hydrogen) preheaters that offer an ample supply of energy and temperature to enable candidate expander engine cycles over a wide range of operating parameters, without reducing the total enthalpy of the core-exit gas and its attendant effect on specific impulse. By modifying the tie tube design concept set forth in LASL's Nuclear Rocket Engine definition study, a powerful, weight and packaging-effective, preheater assembly can be realized. The design features of these tie tube assemblies reflect their functional objectives, core criticality considerations, and space constraints. Since the core pressure and inertial mass loads are carried by these assemblies, the structural tubular element(s) also provide coolant passage(s) for the hydrogen. The transfer of heat to the coolant surfaces is controlled by the effective thermal conductivity of the filler structure and ``insulating sleeves,'' which surround the tubular elements and are in controlled thermal contact with the surrounding core fuel elements. An option exists to further increase the transported heat to the coolant walls by the selective loading of the filler structure, ``insulating sleeves,'' and the moderator annular element with fissionable material.

  18. Leak rate and burst test data for McGuire Unit 1 steam generator tubes

    Energy Technology Data Exchange (ETDEWEB)

    Sherburne, P.A. [B& W Nuclear Service Co., Lynchburg, VA (United States); Frye, C.R. [Babcock & Wilcox Co., Lynchburg, VA (United States); Mayes, D.B. [Duke Power Co., Charlotte, NC (United States)

    1992-12-31

    To support the development of tube plugging criteria that would allow tubes with through-wall cracks to remain in service, sections of 12 tubes were removed from the McGuire Unit-1 steam generators. These tubes were sent to B&W Nuclear Service Company for metallographic examination and for determination of burst pressure and leak rate at both operating and faulted conditions. Primary water stress corrosion cracking (PWSCC) had degraded these tubes in the tube-to-tubesheet roll transitions. To measure primary-to-secondary leakage at pressures and temperatures equivalent to those in the McGuire Unit-1 steam generators, an autoclave-based test loop was designed and installed at the Babcock & Wilcox Lynchburg Research Center. Sections of the tube containing the roll transitions were then installed in the autoclave and actual primary- to-secondary leakage was measured at 288{degrees}C (550{degrees}F) and at 9 and 18.3 MPa (1300 and 2650 psi) pressure differentials. Following the leak test, the tubes were pressurized internally until the tube wall ruptured. Leak rate, burst pressure, and eddy-current information were then correlated with the through-wall crack lengths as determined by metallographic examination. Results confirm the ability to measure the crack length with eddy-current techniques. Results also support analytical and empirical models developed by the nuclear industry in calculating critical crack lengths in roll transitions.

  19. Research of laser cleaning technology for steam generator tubing

    Science.gov (United States)

    Hou, Suixa; Luo, Jijun; Xu, Jun; Yuan, Bo

    2010-10-01

    Surface cleaning based on the laser-induced breakdown of gas and subsequent shock wave generation can remove small particles from solid surfaces. Accordingly, several studies in steam generator tubes of nuclear power plants were performed to expand the cleaning capability of the process. In this work, experimental apparatus of laser cleaning was designed in order to clean heat tubes in steam generator. The laser cleaning process is monitored by analyzing acoustic emission signal experimentally. Experiments demonstrate that laser cleaning can remove smaller particles from the surface of steam generator tubes better than other cleaning process. It has advantages in saving on much manpower and material resource, and it is a good cleaning method for heat tubes, which can be real-time monitoring in laser cleaning process of heat tubes by AE signal. As a green cleaning process, laser cleaning technology in equipment maintenance will be a good prospect.

  20. Prognostics for Steam Generator Tube Rupture using Markov Chain model

    Energy Technology Data Exchange (ETDEWEB)

    Kim, Gibeom; Heo, Gyunyoung [Kyung Hee University, Yongin (Korea, Republic of); Kim, Hyeonmin [Korea Atomic Energy Research Institute, Daejeon (Korea, Republic of)

    2016-10-15

    This paper will describe the prognostics method for evaluating and forecasting the ageing effect and demonstrate the procedure of prognostics for the Steam Generator Tube Rupture (SGTR) accident. Authors will propose the data-driven method so called MCMC (Markov Chain Monte Carlo) which is preferred to the physical-model method in terms of flexibility and availability. Degradation data is represented as growth of burst probability over time. Markov chain model is performed based on transition probability of state. And the state must be discrete variable. Therefore, burst probability that is continuous variable have to be changed into discrete variable to apply Markov chain model to the degradation data. The Markov chain model which is one of prognostics methods was described and the pilot demonstration for a SGTR accident was performed as a case study. The Markov chain model is strong since it is possible to be performed without physical models as long as enough data are available. However, in the case of the discrete Markov chain used in this study, there must be loss of information while the given data is discretized and assigned to the finite number of states. In this process, original information might not be reflected on prediction sufficiently. This should be noted as the limitation of discrete models. Now we will be studying on other prognostics methods such as GPM (General Path Model) which is also data-driven method as well as the particle filer which belongs to physical-model method and conducting comparison analysis.

  1. Evaluation of machine learning tools for inspection of steam generator tube structures using pulsed eddy current

    Science.gov (United States)

    Buck, J. A.; Underhill, P. R.; Morelli, J.; Krause, T. W.

    2017-02-01

    Degradation of nuclear steam generator (SG) tubes and support structures can result in a loss of reactor efficiency. Regular in-service inspection, by conventional eddy current testing (ECT), permits detection of cracks, measurement of wall loss, and identification of other SG tube degradation modes. However, ECT is challenged by overlapping degradation modes such as might occur for SG tube fretting accompanied by tube off-set within a corroding ferromagnetic support structure. Pulsed eddy current (PEC) is an emerging technology examined here for inspection of Alloy-800 SG tubes and associated carbon steel drilled support structures. Support structure hole size was varied to simulate uniform corrosion, while SG tube was off-set relative to hole axis. PEC measurements were performed using a single driver with an 8 pick-up coil configuration in the presence of flat-bottom rectangular frets as an overlapping degradation mode. A modified principal component analysis (MPCA) was performed on the time-voltage data in order to reduce data dimensionality. The MPCA scores were then used to train a support vector machine (SVM) that simultaneously targeted four independent parameters associated with; support structure hole size, tube off-centering in two dimensions and fret depth. The support vector machine was trained, tested, and validated on experimental data. Results were compared with a previously developed artificial neural network (ANN) trained on the same data. Estimates of tube position showed comparable results between the two machine learning tools. However, the ANN produced better estimates of hole inner diameter and fret depth. The better results from ANN analysis was attributed to challenges associated with the SVM when non-constant variance is present in the data.

  2. Magnetic flux tubes as sources of wave generation

    Science.gov (United States)

    Musielak, Z. E.; Rosner, R.; Ulmschneider, P.

    1987-01-01

    The structure of solar, and very likely stellar, surface magnetic fields is highly inhomogeneous: at the photospheric level, the fields are locally strong, and show concentration into a flux tube structure. In this case, the wave energy generated in stellar convection zones may be largely carried away by flux tube waves, which can then become important sources for the heating of the outer atmospheric layers. Such flux tube wave generation may help to explain the UV and X-ray fluxes observed by the IUE and Einstein observatories. The generation of longitudinal tube waves in magnetic flux tubes embedded in an otherwise magnetic field-free, turbulent, and stratified medium was considered. It is shown that compressible tube waves are generated by dipole emission and that the generation efficiency is a strong function of the magnetic field strength. Energy flux calculations are presented for different magnetic flux tubes, and show how the results depend on the magnetic field strength and the characteristics of the convective turbulence.

  3. Condition assessment and trending of condenser tube degradation for condenser life extension

    Science.gov (United States)

    Friant, C. Lee; Schlegel, Jennifer L.

    1995-05-01

    Eddy current testing (ET) is routinely used to assess tubing condition in heat exchangers at power plants. Generally, ET results provided by typical final report formats are not well- suited for facilitating condition assessments, especially when the component has a significant number of tubes. The main condenser at Calvert Cliffs Nuclear Power Plant (CCNPP) Unit #1 contains nearly 50,000 tubes. An accurate condition assessment based on 2,500 pages of final reports generated from a 100% condenser inspection in 1992 proved difficult, if not impossible, without some type of automated data management system. With the aid of a data management system, engineering recommendations, founded on database queries and graphics, can be made quickly and reliably. These displays effectively communicate information about overall condition, are helpful in making operating decisions, and aid in predicting future performance. Standard procedures for critical heat exchanger inspections require trending of indication growth over time to determine a rate of tube degradation. Specifically, for the 1994 ET inspection of CCNPP Unit #1 condenser, the size of indications were compared against their 1992 value to determine a mean growth rate. The results of these efforts are presented along with a discussion of how Baltimore Gas and Electric has used eddy current data to prolong the operating life of this condenser while ensuring leak tightness.

  4. Estimating probable flaw distributions in PWR steam generator tubes

    Energy Technology Data Exchange (ETDEWEB)

    Gorman, J.A.; Turner, A.P.L. [Dominion Engineering, Inc., McLean, VA (United States)

    1997-02-01

    This paper describes methods for estimating the number and size distributions of flaws of various types in PWR steam generator tubes. These estimates are needed when calculating the probable primary to secondary leakage through steam generator tubes under postulated accidents such as severe core accidents and steam line breaks. The paper describes methods for two types of predictions: (1) the numbers of tubes with detectable flaws of various types as a function of time, and (2) the distributions in size of these flaws. Results are provided for hypothetical severely affected, moderately affected and lightly affected units. Discussion is provided regarding uncertainties and assumptions in the data and analyses.

  5. Evaluation of steam generator WWER 440 tube integrity criteria

    Energy Technology Data Exchange (ETDEWEB)

    Splichal, K.; Otruba, J.; Burda, J. [Nuclear Research Institute Rez plc. (Czechoslovakia)

    1997-02-01

    The main corrosion damage in WWER steam generators under operating conditions has been observed on the outer surface of these tubes. An essential operational requirement is to assure a low probability of radioactive primary water leakage, unstable defect development and rupture of tubes. In the case of WWER 440 steam generators the above requirements led to the development of permissible limits for data evaluation of the primary-to-secondary leak measurements and determination of acceptable values for plugging of heat exchange tubes based on eddy current test (ECT) inspections.

  6. Correlation between General Corrosion Behavior and Eddy Current Noise of Alloy 690 Steam Generator Tube

    Energy Technology Data Exchange (ETDEWEB)

    Hur, Do Haeng; Choi, Myung Sik; Lee, Deok Hyun; Shim, Hee-Sang [Korea Atomic Energy Research Institute, Daejeon (Korea, Republic of)

    2015-05-15

    Nickel and its oxides are released from the surface of steam generator tubes into the primary water. Released nickel and cobalt is activated to Co-58 and Co-60 in the reactor core by a neutron flux, respectively. These activated corrosion products are the main source of high radiation fields and occupational radiation exposure. In addition, some of the corrosion products redeposit on the fuel cladding, hinder the heat transfer, increase the corrosion rate of the fuel cladding, and finally induce an axial offset anomaly. This phenomenon can decrease core shutdown margin, and thus lead to a down-rating of a plant. Recently, many researchers have reported that the surface states of Alloy 690 tubes affect the corrosion product formation and its release in simulated primary water environments. Meanwhile, the surface states of steam generator tubes affect the noise level of eddy current testing. Noise signals arising from the tubes degrade the probability of detection and sizing accuracy of the defects. The corrosion behavior was closely correlated to the tube noise measured using a rotating probe, while it was not related to the noise measured using a bobbin probe. It is suggested that the tube noise value measured using a rotating pancake coil probe can be a decisive measure to estimate the corrosion behavior of tubing.

  7. Testing and analysis of tube voltage and tube current in the radiation generator for mammography

    Energy Technology Data Exchange (ETDEWEB)

    Jung, Hong Ryang; Hong, Dong Hee [Dept. of Health Care, Hanseo University, Seosan (Korea, Republic of); Han, Beom Hui [Dept. of Radiological Science, Seonam University, Namwon (Korea, Republic of)

    2014-03-15

    Breast shooting performance management and quality control of the generator is applied to the amount of current IEC(International Electrotechnical Commission) 60601-2-45 tube voltage and tube current are based on standards that were proposed in the analysis of the test results were as follows. Tube voltage according to the value of the standard deviation by year of manufacture from 2001 to 2010 as a 42-3.15 showed the most significant, according to the year of manufacture by tube amperage value of the standard deviation to 6.38 in the pre-2000 showed the most significant , manufactured after 2011 the standard deviation of the devices, the PAE(Percent Average Error) was relatively low. This latest generation device was manufactured in the breast of the tube voltage and tube diagnosed shooting the correct amount of current to maintain the performance that can be seen. The results of this study as the basis for radiography diagnosed breast caused by using the device's performance and maintain quality control, so the current Food and Drug Administration 'about the safety of diagnostic radiation generator rule' specified in the test cycle during three years of self-inspection radiation on a radiation generating device ensure safety and performance of the device using a coherent X-ray(constancy) by two ultimately able to keep the radiation dose to the public to reduce the expected effect is expected.

  8. A second-generation constrained reaction volume shock tube.

    Science.gov (United States)

    Campbell, M F; Tulgestke, A M; Davidson, D F; Hanson, R K

    2014-05-01

    We have developed a shock tube that features a sliding gate valve in order to mechanically constrain the reactive test gas mixture to an area close to the shock tube endwall, separating it from a specially formulated non-reactive buffer gas mixture. This second-generation Constrained Reaction Volume (CRV) strategy enables near-constant-pressure shock tube test conditions for reactive experiments behind reflected shocks, thereby enabling improved modeling of the reactive flow field. Here we provide details of the design and operation of the new shock tube. In addition, we detail special buffer gas tailoring procedures, analyze the buffer/test gas interactions that occur on gate valve opening, and outline the size range of fuels that can be studied using the CRV technique in this facility. Finally, we present example low-temperature ignition delay time data to illustrate the CRV shock tube's performance.

  9. A second-generation constrained reaction volume shock tube

    Science.gov (United States)

    Campbell, M. F.; Tulgestke, A. M.; Davidson, D. F.; Hanson, R. K.

    2014-05-01

    We have developed a shock tube that features a sliding gate valve in order to mechanically constrain the reactive test gas mixture to an area close to the shock tube endwall, separating it from a specially formulated non-reactive buffer gas mixture. This second-generation Constrained Reaction Volume (CRV) strategy enables near-constant-pressure shock tube test conditions for reactive experiments behind reflected shocks, thereby enabling improved modeling of the reactive flow field. Here we provide details of the design and operation of the new shock tube. In addition, we detail special buffer gas tailoring procedures, analyze the buffer/test gas interactions that occur on gate valve opening, and outline the size range of fuels that can be studied using the CRV technique in this facility. Finally, we present example low-temperature ignition delay time data to illustrate the CRV shock tube's performance.

  10. Structural and leakage integrity assessment of WWER steam generator tubes

    Energy Technology Data Exchange (ETDEWEB)

    Splichal, K.; Otruba, J. [Nuclear Research Inst., Rez (Switzerland)

    1997-12-31

    The integrity of heat exchange tubes may influence the life-time of WWER steam generators and appears to be an important criterion for the evaluation of their safety and operational reliability. The basic requirement is to assure a very low probability of radioactive water leakage, preventing unstable crack growth and sudden tube rupture. These requirements led to development of permissible limits for primary to secondary leak evolution and heat exchange tubes plugging based on eddy current test inspection. The stress corrosion cracking and pitting are the main corrosion damage of WWER heat exchange tubes and are initiated from the outer surface. They are influenced by water chemistry, temperature and tube wall stress level. They take place under crevice corrosion condition and are indicated especially (1) under the tube support plates, where up to 90-95 % of defects detected by the ECT method occur, and (2) on free spans under tube deposit layers. Both the initiation and crack growth cause thinning of the tube wall and lead to part thickness cracks and through-wall cracks, oriented above all in the axial direction. 10 refs.

  11. Anatomy Education for the YouTube Generation

    Science.gov (United States)

    Barry, Denis S.; Marzouk, Fadi; Chulak-Oglu, Kyrylo; Bennett, Deirdre; Tierney, Paul; O'Keeffe, Gerard W.

    2016-01-01

    Anatomy remains a cornerstone of medical education despite challenges that have seen a significant reduction in contact hours over recent decades; however, the rise of the "YouTube Generation" or "Generation Connected" (Gen C), offers new possibilities for anatomy education. Gen C, which consists of 80% Millennials, actively…

  12. Subcooled choked flow through steam generator tube cracks

    Science.gov (United States)

    Wolf, Brian J.

    The work presented here describes an experimental investigation into the choked flow of initially subcooled water through simulated steam generator tube cracks at pressures up to 6.9 MPa. The study of such flow is relevant to the prediction of leak flow rates from a nuclear reactor primary side to secondary side through cracks in steam generator tubes. An experimental approach to measuring such flow is de- scribed. Experimental results from data found in literature as well as the data collected in this work are compared with predictions from presented models as well as predictions from the thermal-hydraulic system code RELAP5. It is found that the homogeneous equilibrium model underpredicts choked flow rates of subcooled water through slits and artificial steam generator tube cracks. Additional modeling of thermal non-equilibrium improves the predictibility of choking mass flux for homogeneous models, however they fail to account for the characteristics of the two-phase pressure drop. An integral modeling approach is enhanced using a correlation developed from the data herein. Also, an assessment of the thermal-hydraulics code RELAP5 is performed and it’s applicability to predict choking flow rates through steam generator tube cracks is addressed. This assessment determined that the Henry & Fauske model, as coded in RELAP5, is best suited for modeling choked flow through steam generator tube cracks. Finally, an approach to applying choked flow data that is not at the same thermo-dynamic conditions as a prototype is developed.

  13. Effect of Ovality on Maximum External Pressure of Helically Coiled Steam Generator Tubes with a Rectangular Wear

    Energy Technology Data Exchange (ETDEWEB)

    Shin, Dong In; Lim, Eun Mo; Huh, Nam Su [Seoul National Univ. of Science and Technology, Seoul (Korea, Republic of); Choi, Shin Beom; Yu, Je Yong; Kim, Ji Ho; Choi, Suhn [Korea Atomic Energy Research Institute, Daejeon (Korea, Republic of)

    2013-10-15

    A structural integrity of steam generator tubes of nuclear power plants is one of crucial parameters for safe operation of nuclear power plants. Thus, many studies have been made to provide engineering methods to assess integrity of defective tubes of commercial nuclear power plants considering its operating environments and defect characteristics. As described above, the geometric and operating conditions of steam generator tubes in integral reactor are significantly different from those of commercial reactor. Therefore, the structural integrity assessment of defective tubes of integral reactor taking into account its own operating conditions and geometric characteristics, i. e., external pressure and helically coiled shape, should be made to demonstrate compliance with the current design criteria. Also, ovality is very specific characteristics of the helically coiled tube because it is occurred during the coiling processes. The wear, occurring from FIV (Flow Induced Vibration) and so on, is main degradation of steam generator tube. In the present study, maximum external pressure of helically coiled steam generator tube with wear is predicted based on the detailed 3-dimensional finite element analysis. As for shape of wear defect, the rectangular shape is considered. In particular, the effect of ovality on the maximum external pressure of helically coiled tubes with rectangular shaped wear is investigated. In the present work, the maximum external pressure of helically coiled steam generator tube with rectangular shaped wear is investigated via detailed 3-D FE analyses. In order to cover a practical range of geometries for defective tube, the variables affecting the maximum external pressure were systematically varied. In particular, the effect of tube ovality on the maximum external pressure is evaluated. It is expected that the present results can be used as a technical backgrounds for establishing a practical structural integrity assessment guideline of

  14. On the generation of flux tube waves in stellar convection zones. I - Longitudinal tube waves driven by external turbulence

    Science.gov (United States)

    Musielak, Z. E.; Rosner, R.; Ulmschneider, P.

    1989-01-01

    The source functions and the energy fluxes for wave generation in magnetic flux tubes embedded in an otherwise magnetic field-free, turbulent, and compressible fluid are derived. The calculations presented here assume that the tube interior is not itself turbulent, e.g., that motions within the flux tube are due simply to external excitation. Specific results for the generation of longitudinal tube waves are presented.

  15. Uncertainty analysis for probabilistic steam generators tube rupture in LBB applications

    Energy Technology Data Exchange (ETDEWEB)

    Durbec, V.; Pitner, P.; Pages, D. [Electricite de France, 78 - Chatou (France). Research and Development Div.; Riffard, T. [Electricite de France, 69 - Villeurbanne (France). Engineering and Construction Div.; Flesch, B. [Electricite de France, 92 - Paris la Defense (France). Generation and Transmission Div.

    1997-10-01

    Steam Generators (SG) of Pressurized Water Reactors have experienced world wide various types of tube degradations, mainly from stress corrosion cracking; because of this damage, primary-secondary leakage or tube rupture can occur. Safety against the risk of tube rupture is achieved through a combination of periodic in-service inspections (eddy current testing), surveillance of leaks during operation (leak before break concept) and tube plugging. In order to optimize the tube bundle SG maintenance, Electricite de France has developed a specific software named COMPROMIS. The model, based on probabilistic fracture mechanics makes it possible to quantify the influence of in service inspections and maintenance work on the risk of a SG Tube Rupture (SGTR), taking all significant parameters into account as random variables (initial defect size distribution, reliability of non-destructive examinations, crack initiation and propagation, critical sizes, leak before risk of break, etc...). This paper focuses on the leak rate calculation module and presents a sensitivity study of the influence of the leak before break on the conditional failure probability. (author) 8 refs.

  16. Second-generation aerosol shock tube: an improved design

    Science.gov (United States)

    Haylett, D. R.; Davidson, D. F.; Hanson, R. K.

    2012-11-01

    An improved, second-generation aerosol shock tube (AST II) has been developed for the study of the chemical kinetics of low-vapor-pressure fuels. These improvements enable a wider range of fuel concentrations and enhanced spatial uniformity relative to our initial aerosol shock tube (AST I). In addition, the design of AST II limits the aerosol loading zone in the shock tube to a fixed region (1.2 m in length adjacent to the shock tube endwall). AST II achieves these improvements using a separate holding tank to prepare the aerosol mixture and a slightly under-pressure dump tank to carefully pull the aerosol mixture into the tube in a plug-flow. This filling method is capable of producing room temperature test gas mixtures of n-dodecane with equivalence ratios of up to 3.0 in 21 % O2, three times the loading achievable in the earlier AST I that used a flow-through strategy. Improvements in aerosol uniformity were quantified by measuring the liquid volume concentration at multiple locations in the shock tube. The measurements made over a length of 1.1 m of shock tube indicate that the AST II method of filling produces non-uniformities in liquid volume concentration of less than 2 %, whereas in the AST I method of filling the non-uniformities reached 16 %. The improved uniformity can also be seen in measurement of gas-phase fuel concentration behind the incident shock wave after the liquid droplets have evaporated. Significant reduction in the scatter of ignition delay times measured using AST II have also been achieved, confirming the importance of uniform loading of the aerosol in making high-quality combustion measurements.

  17. Analysis of the State of Steam Generator Tubes

    Energy Technology Data Exchange (ETDEWEB)

    Bergunker, Olga [JSC OKB ' Gidropress' , 142103 Podolsk (Russian Federation)

    2008-07-01

    The problem of safe operation of SG heat exchanging tubes, of both economical and effective control of their state is still important these days. Issues connected with peculiarities of methods of SG tubes inspection, automated analysis of the inspection results, tubes state analysis and development of algorithms of forecasting their state are considered in this report. The need for effective use of extensive data arrays on SG operation has led to the necessity of creating software tools for collection, storage and analysis of these data. The data-analytical system 'NPP Steam Generators' meant for data systematization and visualization as well as various types of analyses of data on eddy current inspection of WWER-440 and WWER-1000 SG tubes is presented in this report. The main possibilities of the data-analytical system (DAS), the code current state and prospects of its development are shown. The main fields of DAS application are considered and some results of its practical use are mentioned, namely, in the field of forecasting SG tubes state. (authors)

  18. Single-tube library preparation for degraded DNA

    DEFF Research Database (Denmark)

    Carøe, Christian; Gopalakrishnan, Shyam; Vinner, Lasse

    2017-01-01

    1.In recent years, massive parallel sequencing has revolutionized the study of degraded DNA, thus enabling the field of ancient DNA to evolve into that of paleogenomics. Despite these advances, the recovery and sequencing of degraded DNA remains challenging due to limitations in the manipulation...... of chemically damaged and highly fragmented DNA molecules. In particular, the enzymatic reactions and DNA purification steps during library preparation can result in DNA template loss and sequencing biases, affecting downstream analyses. The development of library preparation methods that circumvent...... these obstacles and enable higher throughput are therefore of interest to researchers working with degraded DNA. 2.In this study, we compare four Illumina library preparation protocols, including two “single-tube” methods developed for this study with the explicit aim of improving data quality and reducing...

  19. Analysis of pulsed eddy current data using regression models for steam generator tube support structure inspection

    Science.gov (United States)

    Buck, J. A.; Underhill, P. R.; Morelli, J.; Krause, T. W.

    2016-02-01

    Nuclear steam generators (SGs) are a critical component for ensuring safe and efficient operation of a reactor. Life management strategies are implemented in which SG tubes are regularly inspected by conventional eddy current testing (ECT) and ultrasonic testing (UT) technologies to size flaws, and safe operating life of SGs is predicted based on growth models. ECT, the more commonly used technique, due to the rapidity with which full SG tube wall inspection can be performed, is challenged when inspecting ferromagnetic support structure materials in the presence of magnetite sludge and multiple overlapping degradation modes. In this work, an emerging inspection method, pulsed eddy current (PEC), is being investigated to address some of these particular inspection conditions. Time-domain signals were collected by an 8 coil array PEC probe in which ferromagnetic drilled support hole diameter, depth of rectangular tube frets and 2D tube off-centering were varied. Data sets were analyzed with a modified principal components analysis (MPCA) to extract dominant signal features. Multiple linear regression models were applied to MPCA scores to size hole diameter as well as size rectangular outer diameter tube frets. Models were improved through exploratory factor analysis, which was applied to MPCA scores to refine selection for regression models inputs by removing nonessential information.

  20. Continuous-wave radar to detect defects within heat exchangers and steam generator tubes.

    Energy Technology Data Exchange (ETDEWEB)

    Nassersharif, Bahram (New Mexico State University, Las Cruces, NM); Caffey, Thurlow Washburn Howell; Jedlicka, Russell P. (New Mexico State University, Las Cruces, NM); Garcia, Gabe V. (New Mexico State University, Las Cruces, NM); Rochau, Gary Eugene

    2003-01-01

    A major cause of failures in heat exchangers and steam generators in nuclear power plants is degradation of the tubes within them. The tube failure is often caused by the development of cracks that begin on the outer surface of the tube and propagate both inwards and laterally. A new technique was researched for detection of defects using a continuous-wave radar method within metal tubing. The experimental program resulted in a completed product development schedule and the design of an experimental apparatus for studying handling of the probe and data acquisition. These tests were completed as far as the prototypical probe performance allowed. The prototype probe design did not have sufficient sensitivity to detect a defect signal using the defined radar technique and did not allow successful completion of all of the project milestones. The best results from the prototype probe could not detect a tube defect using the radar principle. Though a more precision probe may be possible, the cost of design and construction was beyond the scope of the project. This report describes the probe development and the status of the design at the termination of the project.

  1. Anatomy education for the YouTube generation.

    Science.gov (United States)

    Barry, Denis S; Marzouk, Fadi; Chulak-Oglu, Kyrylo; Bennett, Deirdre; Tierney, Paul; O'Keeffe, Gerard W

    2016-01-01

    Anatomy remains a cornerstone of medical education despite challenges that have seen a significant reduction in contact hours over recent decades; however, the rise of the "YouTube Generation" or "Generation Connected" (Gen C), offers new possibilities for anatomy education. Gen C, which consists of 80% Millennials, actively interact with social media and integrate it into their education experience. Most are willing to merge their online presence with their degree programs by engaging with course materials and sharing their knowledge freely using these platforms. This integration of social media into undergraduate learning, and the attitudes and mindset of Gen C, who routinely creates and publishes blogs, podcasts, and videos online, has changed traditional learning approaches and the student/teacher relationship. To gauge this, second year undergraduate medical and radiation therapy students (n = 73) were surveyed regarding their use of online social media in relation to anatomy learning. The vast majority of students had employed web-based platforms to source information with 78% using YouTube as their primary source of anatomy-related video clips. These findings suggest that the academic anatomy community may find value in the integration of social media into blended learning approaches in anatomy programs. This will ensure continued connection with the YouTube generation of students while also allowing for academic and ethical oversight regarding the use of online video clips whose provenance may not otherwise be known.

  2. Finite element modeling of wall-loss sizing in a steam generator tube using a pulsed eddy current probe

    Science.gov (United States)

    Babbar, V. K.; Lepine, B.; Buck, J.; Underhill, P. R.; Morelli, J.; Krause, T. W.

    2015-03-01

    Inspection of steam generator (SG) tubes by conventional eddy current may, in general, involve analysis of indications from volumetric wall loss, cracks, fouling and support-plate degradation; however, it may be difficult to size or quantify effects from support-to-tube gap and tube tilt, especially in the presence of support plates. Pulsed eddy current (PEC) technology is being developed to investigate such complex tube and flaw geometries. The present work employs finite element modeling to investigate the effectiveness of PEC in identifying and sizing the outer diameter wall-loss in SG tubes. The signals analyzed using a modified principal components analysis (PCA) method reveal the potential success of a PEC-PCA combination to produce scores that can be used to size the wall-loss in the presence of support plates. The modeling results are in good agreement with experimental observations.

  3. Process Technology Development of Ni Electroplating in Steam Generator Tube

    Energy Technology Data Exchange (ETDEWEB)

    Kim, Joung Soo; Kim, H. P.; Lim, Y. S.; Kim, S. S.; Hwang, S. S.; Yi, Y. S.; Kim, D. J.; Jeong, M. K.

    2009-11-15

    Operating nuclear power steam generator tubing material, Alloy 600, having superior resistance to corrosion has many experiences of damage by various corrosion mechanisms during long term operation period. In this research project, a new Ni electroplating technology to be applied to repair the damaged steam generator tubes has been developed. In this technology development, the optimum conditions for variables affecting the Ni electroplating process, optimum process conditions for maximum adhesion forces at interface between were established. The various mechanical properties (RT and HT tensile, fatigue, creep, burst, etc.) and corrosion properties (general corrosion, pitting, crevice corrosion, stress corrosion cracking, boric acid corrosion, doped steam) of the Ni plated layers made at the established optimum conditions have been evaluated and confirmed to satisfy the specifications. In addition, a new ECT probe developed at KAERI enable to detect defects from magnetic materials was confirmed to be used for Ni electroplated Alloy 600 tubes at the field. For the application of this developed technology to operating plants, a mock-up electroplating system has been designed and manufactured, and set up at Doosan Heavy Industry Co. and also its performance test has been done. At same time, the anode probe has been modified and improved to be used with the established mock-up system without any problem

  4. A pulsed eddy current probe for inspection of support plates from within Alloy-800 steam generator tubes

    Energy Technology Data Exchange (ETDEWEB)

    Krause, T. W.; Babbar, V. K.; Underhill, P. R. [Department of Physics, Royal Military College of Canada, Kingston, ON (Canada)

    2014-02-18

    Support plate degradation and fouling in nuclear steam generators (SGs) can lead to SG tube corrosion and loss of efficiency. Inspection and monitoring of these conditions can be integrated with preventive maintenance programs, thereby advancing station-life management processes. A prototype pulsed eddy current (PEC) probe, targeting inspection issues associated with SG tubes in SS410 tube support plate structures, has been developed using commercial finite element (FE) software. FE modeling was used to identify appropriate driver and pickup coil configurations for optimum sensitivity to changes in gap and offset for Alloy-800 SG tubes passing through 25 mm thick SS410 support plates. Experimental measurements using a probe that was manufactured based on the modeled configuration, were used to confirm the sensitivity of differential PEC signals to changes in relative position of the tube within the tube support plate holes. Models investigated the effect of shift and tilt of tube with respect to hole centers. Near hole centers and for small shifts, modeled signal amplitudes from the differentially connected coil pairs were observed to change linearly with tube shift. This was in agreement with experimentally measured TEC coil response. The work paves the way for development of a system targeting the inspection and evaluation of support plate structures in steam generators.

  5. A pulsed eddy current probe for inspection of support plates from within Alloy-800 steam generator tubes

    Science.gov (United States)

    Krause, T. W.; Babbar, V. K.; Underhill, P. R.

    2014-02-01

    Support plate degradation and fouling in nuclear steam generators (SGs) can lead to SG tube corrosion and loss of efficiency. Inspection and monitoring of these conditions can be integrated with preventive maintenance programs, thereby advancing station-life management processes. A prototype pulsed eddy current (PEC) probe, targeting inspection issues associated with SG tubes in SS410 tube support plate structures, has been developed using commercial finite element (FE) software. FE modeling was used to identify appropriate driver and pickup coil configurations for optimum sensitivity to changes in gap and offset for Alloy-800 SG tubes passing through 25 mm thick SS410 support plates. Experimental measurements using a probe that was manufactured based on the modeled configuration, were used to confirm the sensitivity of differential PEC signals to changes in relative position of the tube within the tube support plate holes. Models investigated the effect of shift and tilt of tube with respect to hole centers. Near hole centers and for small shifts, modeled signal amplitudes from the differentially connected coil pairs were observed to change linearly with tube shift. This was in agreement with experimentally measured TEC coil response. The work paves the way for development of a system targeting the inspection and evaluation of support plate structures in steam generators.

  6. Inspection of ferromagnetic support structures from within alloy 800 steam generator tubes using pulsed eddy current

    Science.gov (United States)

    Buck, Jeremy Andrew

    Nondestructive testing is a critical aspect of component lifetime management. Nuclear steam generator (SG) tubes are the thinnest barrier between irradiated primary heat transport system and the secondary heat transport system, whose components are not rated for large radiation fields. Conventional eddy current testing (ECT) and ultrasonic testing are currently employed for inspecting SG tubes, with the former doing most inspections due to speed and reliability based on an understanding of how flaws affect coil impedance parameters when conductors are subjected to harmonically induced currents. However, when multiple degradation modes are present simultaneously near ferromagnetic materials, such as tube fretting, support structure corrosion, and magnetite fouling, ECT reliability decreases. Pulsed eddy current (PEC), which induces transient eddy currents via square wave excitation, has been considered in this thesis to simultaneously examine SG tube and support structure conditions. An array probe consisting of a central driver, coaxial with the tube, and an array of 8 sensing coils, was used in this thesis to perform laboratory measurements. The probe was delivered from the inner diameter (ID) of the SG tube, where support hole diameter, tube frets, and 2D off-centering were varied. When considering two variables simultaneously, scores obtained from a modified principal components analysis (MPCA) were sufficient for parameter extraction. In the case of hole ID variation with two dimensional tube off-centering (three parameters), multiple linear regression (MLR) of the MPCA scores provided good estimates of parameters. However, once a fourth variable, outer diameter tube frets, was introduced, MLR proved insufficient. Artificial neural networks (ANNs) were investigated in order to perform pattern recognition on the MPCA scores to simultaneously extract the four measurement parameters from the data. All models throughout this thesis were created and validated using

  7. Continuous-Wave Radar to Detect Defects Within Heat Exchangers and Steam Generator Tubes ; Revised September 3, 2003

    Energy Technology Data Exchange (ETDEWEB)

    Gary E. Rochau and Thurlow W.H. Caffey, Sandia National Laboratories, Albuquerque, NM 87185-0740; Bahram Nassersharif and Gabe V. Garcia, Department of Mechanical Engineering, New Mexico State University, Las Cruces, NM 88003-8001; Russell P. Jedlicka, Klipsch School of Electrical and Computer Engineering, New Mexico State University, Las Cruces, NM 88003-8001

    2003-05-01

    OAK B204 Continuous-Wave Radar to Detect Defects Within Heat Exchangers and Steam Generator Tubes ; Revised September 3, 2003. A major cause of failures in heat exchangers and steam generators in nuclear power plants is degradation of the tubes within them. The tube failure is often caused by the development of cracks that begin on the outer surface of the tube and propagate both inwards and laterally. A new technique was researched for detection of defects using a continuous-wave radar method within metal tubing. The technique is 100% volumetric, and may find smaller defects, more rapidly, and less expensively than present methods. The project described in this report was a joint development effort between Sandia National Laboratories (SNL) and New Mexico State University (NMSU) funded by the US Department of Energy. The goal of the project was to research, design, and develop a new concept utilizing a continuous wave radar to detect defects inside metallic tubes and in particular nuclear plant steam generator tubing. The project was divided into four parallel tracks: computational modeling, experimental prototyping, thermo-mechanical design, and signal detection and analysis.

  8. Experimental verification of the horizontal steam generator boil-off transfer degradation at natural circulation

    Energy Technology Data Exchange (ETDEWEB)

    Hyvaerinen, J. [Finnish Centre for Radiation and Nuclear Safety, Helsinki (Finland); Kouhia, J. [VTT Energy, Lappeenranta (Finland)

    1997-12-31

    The presentation summarises the highlights of experimental results obtained for VVER type horizontal steam generator heat transfer, primary side flow pattern, and mixing in the hot collector during secondary side boil-off with primary at single-phase natural circulation. The experiments were performed using the PACTEL facility with Large Diameter (LD) steam generator models, with collector instrumentation designed specifically for these tests. The key findings are as follows: (1) the primary to secondary heat transfer degrades as the secondary water inventory is depleted, following closely the wetted tube area; (2) a circulatory flow pattern exists in the tube bundle, resulting in reversed flow (from cold to the hot collector) in the lower part of the tube bundle, and continuous flow through the upper part, including the tubes that have already dried out; and (3) mixing of the hot leg flow entering the hot collector and reversed, cold, tube flow remains confined within the collector itself, extending only a row or two above the elevation at which tube flow reversal has taken place. 6 refs.

  9. Structural integrity assessments of steam generator tubes using the FAD methodology

    Energy Technology Data Exchange (ETDEWEB)

    Bergant, Marcos A., E-mail: marcos.bergant@cab.cnea.gov.ar [Gerencia CAREM, Centro Atómico Bariloche (CNEA), Av. Bustillo 9500, San Carlos de Bariloche 8400 (Argentina); Yawny, Alejandro A., E-mail: yawny@cab.cnea.gov.ar [División Física de Metales, Centro Atómico Bariloche (CNEA)/CONICET, Av. Bustillo 9500, San Carlos de Bariloche 8400 (Argentina); Perez Ipiña, Juan E., E-mail: juan.perezipina@fain.uncoma.edu.ar [Grupo Mecánica de Fractura, Universidad Nacional del Comahue/CONICET, Buenos Aires 1400, Neuquén 8300 (Argentina)

    2015-12-15

    Highlights: • The Failure Assessment Diagram (FAD) is used to assess cracked steam generator tubes. • Typical loading conditions and reported tensile and fracture properties are used. • The FAD is capable to predict the failure mode for different cracks and loads. • The FAD can be used to reduce the conservatism of the current plugging criteria. • Appropriate tensile and fracture properties at operating conditions are required. - Abstract: Steam generator tubes (SGTs) represents up to 60% of the total primary pressure retaining boundary area of a nuclear power plant. They have been found susceptible to diverse degradation mechanisms during service. Due to the significance of a SGT failure on the plant safe operation, nuclear regulatory authorities have established tube plugging or repairing criteria which are based on the defect depth. The widespreadly used “40% criterion” proposed in the 70s is an example whose use is still recommended in the last editions of the ASME Boiler and Pressure Vessel Code. In the present work, an alternative, more realistic and less conservative methodology for SGT integrity evaluation is proposed. It is based on the Failure Assessment Diagram (FAD) and takes advantage of the recent developments in non-destructive techniques which allow a more comprehensive characterization of tube defects, i.e., depth, length, orientation and type. The proposed approach has been applied to: the study of the influence of primary and secondary stresses on tube integrity; the prediction of failure mode (i.e., ductile fracture or plastic collapse) of defective SGTs for varied crack geometries and loading conditions; the analysis of the sensibility of tensile and fracture properties with temperature. The potentiality of the FAD as a comprehensive methodology for predicting the failure loads and failure modes of flawed SGTs is highlighted.

  10. Degradation of finned tubes heat exchangers in presence of non condensable gases and aerosols

    Energy Technology Data Exchange (ETDEWEB)

    Jose L Munoz-Cobo; Pena, J. [Universidad Politecnica de Valencia, Department of Chemical and Nuclear Engineering, Camino de Vera 14, Valencia 46022 (Spain); Luis E Herranz [CIEMAT, Departmen of Nuclear Fision, Avenida Complutense 22, Madrid 28040 (Spain)

    2005-07-01

    Full text of publication follows: If a severe accident occurs in a nuclear power plant, then large amounts of steam and aerosols will enter to the containment, increasing the pressure and the temperature inside the containment building. To reduce these thermal and pressure loads, the next generation of European Passive Nuclear Power Plants, incorporates into the containment passive heat exchangers (HX) driven by natural circulation. These passive HX condense the steam inside the containment and transport by natural circulation the heat to a large pool with capability to act as a heat sink at least during 72 hours. These innovative passive systems consist of several units of horizontal or slightly inclined finned tubes bundles internally cooled by water. The cooling water is heated inside the tubes by the condensation heat removed from the containment and moves by natural circulation to a large pool located outside the containment. The main problem that arises in this kind of HX, is the degradation in the heat transfer produced by the non-condensable gases and the aerosols that are present in large amounts after a severe accident inside the containment. This degradation can increase the containment loads after a severe accident and we must be able to predict this effect as better as possible. This paper presents a mechanistic model to predict the steam condensation on containment finned tube heat exchangers in the presence of non-condensable gases (NC) and aerosols. The total thermal resistance from the bulk gas to the coolant is formulated as a parallel combination of the convective and condensation gas resistances coupled in series to those of condensate layer, the aerosol fouling layer, the wall, and the coolant. The condensate layer thermal resistance is calculated by means of an Adamek-based condensation model. The aerosol fouling layer is computed based on diffusiophoresis, settling and impaction mechanisms. The gas mixture (Steam plus NC) thermal resistance

  11. Probabilistic integrity assessment of CANDU pressure tube for the consideration of flaw generation time

    Energy Technology Data Exchange (ETDEWEB)

    Kwak, Sang Log; Kim, Young Jin [Sungkyunkwan Univ., Seoul (Korea, Republic of); Lee, Joon Seong [Kyonggi Univ., Seoul (Korea, Republic of); Park, Youn Won [KINS, Taejon (Korea, Republic of)

    2001-07-01

    This paper describes a Probabilistic Fracture Mechanics (PFM) analysis based on Monte Carlo (MC) simulation. In the analysis of CANDU pressure tube, it is necessary to perform the PFM analyses based on statistical consideration of flaw generation time. A depth and an aspect ratio of initial semi-elliptical surface crack, a fracture toughness value, Delayed Hydride Cracking (DHC) velocity, and flaw generation time are assumed to be probabilistic variables. In all the analyses, degradation of fracture toughness due to neutron irradiation is considered. Also, the failure criteria considered are plastic collapse, unstable fracture and crack penetration. For the crack growth by DHC, the failure probability was evaluated in due consideration of flaw generation time.

  12. Direct solar steam generation inside evacuated tube absorber

    Directory of Open Access Journals (Sweden)

    Khaled M. Bataineh

    2016-12-01

    Full Text Available Direct steam generation by solar radiation falling on absorber tube is studied in this paper. A system of single pipe covered by glass material in which the subcooled undergoes heating and evaporation process is analyzed. Mathematical equations are derived based on energy, momentum and mass balances for system components. A Matlab code is built to simulate the flow of water inside the absorber tube and determine properties of water along the pipe. Widely accepted empirical correlations and mathematical models of turbulent flow, pressure drop for single and multiphase flow, and heat transfer are used in the simulation. The influences of major parameters on the system performance are investigated. The pressure profiles obtained by present numerical solution for each operation condition (3 and 10 MPa matches very well experimental data from the DISS system of Plataforma Solar de Almería. Furthermore, results obtained by simulation model for pressure profiles are closer to the experimental data than those predicted by already existed other numerical model.

  13. Harmonic Generation in a Traveling-Wave Tube

    Science.gov (United States)

    Wong, Patrick; Zhang, Peng; Lau, Y. Y.; Greening, Geoffrey; Gilgenbach, Ronald; Chernin, David; Simon, David; Hoff, Brad

    2016-10-01

    Crowding of electron orbits in a traveling-wave tube (TWT) may lead to significant harmonic contents in the beam current, even in the linear regime. Here, we consider a wideband TWT that exhibits gain at the second harmonic. We analytically formulate equations governing the evolution of the generation of second harmonic, including axial variations of the Pierce parameters. The second harmonic output is phase-controlled by the input signal which consists only of a fundamental frequency. Several test cases are performed and compared with simulation using the CHRISTINE code. Reasonable agreement between theory and simulation is found. Work supported by AFOSR FA9550-15-1-0097, ONR N00014-16-1-2353, and L-3 Communications Electron Device Division.

  14. Next-generation sequencing offers new insights into DNA degradation

    DEFF Research Database (Denmark)

    Overballe-Petersen, Søren; Orlando, Ludovic Antoine Alexandre; Willerslev, Eske

    2012-01-01

    The processes underlying DNA degradation are central to various disciplines, including cancer research, forensics and archaeology. The sequencing of ancient DNA molecules on next-generation sequencing platforms provides direct measurements of cytosine deamination, depurination and fragmentation r...

  15. Inducement of IGA/SCC in Inconel 600 steam generator tubing during unit outages

    Energy Technology Data Exchange (ETDEWEB)

    Durance, D.; Sedman, K. [Bruce Power, Tiverton, Ontario (Canada); Roberts, J. [CANTECH Associates Ltd., Burlington, Ontario (Canada); King, P. [Babcock and Wilcox Canada, Cambridge, Ontario (Canada); Gorman, J. [Dominion Engineering, Reston, VA (United States); Allen, R. [Kinectrics, Inc., Toronto, Ontario (Canada)

    2008-07-01

    The degradation of Unit 4 SG tubing by IGA/SCC has limited both the operating period and end of life predictions for Unit 4 since restart in late 2003. The circumferential IGA/SCC has been most significant in SG4 with substantial increases in both initiation and growth rates from 2005 through the spring of 2007. A detailed review of the occurrence of circumferential OD IGA/SCC at the RTZ in the HL TTS region of Bruce 4 steam generator tubes has led a conclusion that it is probable that the IGA/SCC has been the result of attack by partially reduced sulfur species such as tetrathionates and thiosulfates during periods of low temperature exposure. It is believed that attack of this type has mostly likely occurred during startup evolutions following outages as the result the development of aggressive reduced sulfur species in the TTS region during periods when the boilers were fully drained for maintenance activities. The modification of outage practices to limit secondary side oxygen ingress in the spring of 2007 has apparently arrested the degradation and has had significant affects on the allowable operating interval and end of life predictions for the entire unit. (author)

  16. Development of safety evaluation technique of steam generator tubes for the next generation

    Energy Technology Data Exchange (ETDEWEB)

    Kwon, Hyuk Sang; Kim, I. S.; Ann, Se Jin; Lee, S. J.; Seo, M. S.; Lee, Y. H.; Kim, J. H.; Hong, J. G. [Korea Advanced Institute of Science and Technology, Taejon (Korea, Republic of)

    2000-02-15

    Subject 1 - a technique for predicting the SCC susceptibility of steam generator tube material based on the repassivation kinetics was developed and the effects of Pb in the repassivation rate and SCC susceptibility rate of tube material was investigated with this technique. An alloy with a higher slope value of log i(t) vs. q(t) plot based on the current transient curve obtained by scratch test and a lower slope value log i(t) vs. l/q(t) plot (cBV) is repassivated faster with a more protective passive film and it can be predicted that it will show higher resistance to SCC. With PbO addition in all solution studied (pH 4, pH 10, Cl- containing pH 4), alloy 690TT showed decreased repassivation rate. So it can be predict that PbO addition lower the resistance of SCC of steam generator tune material. Subject 2 - SG wear testing of tube and support materials has been conducted at various load and sliding amplitude in air environment. The results showed effect of normal load and sliding amplitude on SG tube wear damage. It was also shown that, for predominantly sliding motion, the SG wear coefficient of work-rate model is lower for Inconel 690TT compared with inconel 600MA. SG tube wear data show that, for work-rates ranging from 4 to 25mW, average tube wear coefficient of 43.76{approx}54.05 X 10{sup 15} Pa{sup -1} for Inconel 600MA and 26.88{approx}33.94 X 10{sup -15} Pa{sup 1} for Inconel 690TT against 405 and 409 stainless steels.

  17. Groundtruth Generation and Document Image Degradation

    Science.gov (United States)

    2005-05-01

    the author in [32] uses this model to design a linear filtering scheme instead of generating synthetic images. The necessity and the work...TrueType specifications”, https://www.microsoft.com/ typography /specs/default.htm [28] Esko Ukkonen, “Algorithm for Approximate String Matching

  18. Numerical and Experimental Study on a Model Draft Tube with Vortex Generators

    Directory of Open Access Journals (Sweden)

    Tian Xiaoqing

    2013-01-01

    Full Text Available A model water turbine draft tube containing vortex generators (VG was studied. Numerical simulations were performed to investigate 55 design variations of the vortex generators in a draft tube. After analyzing the shapes of streamlines and velocity distributions in the tube and comparing static pressure recovery coefficients (SPRC in different design variations, an optimum vortex generator layout, which can raise SPRC of the draft tube by 4.8 percent, was found. To verify the effectiveness of the vortex generator application, a series of experiments were carried out. The results show that by choosing optimal vortex generator parameters, such as the installation type, installation position, blade-to-blade distance, and blade inclination angle, the draft tube equipped vortex generators can effectively raise their SPRC andworking stability.

  19. Corrosion behaviour of a stream generator tube material in simulated steam generator feedwater containing chlorides and sulphates

    Energy Technology Data Exchange (ETDEWEB)

    Bojinov, M.; Kinnunen, P.; Laitinen, T.; Maekelae, K.; Saario, T.; Sirkiae, P.; Yliniemi, K. [VTT Manufacturing Technology, Espoo (Finland); Buddas, T.; Halin, M.; Tompuri, K. [Fortum Power and Heat Oy, Loviisa Power Plant (Finland)

    2002-07-01

    The goal of the present work has been to assess the effect of relatively high concentrations of anionic impurities (Cl{sup -}, SO{sub 4}{sup 2-}) on the corrosion behaviour of Ti-stabilised stainless steel SG tubes in simulated steam generator feed-water. The main observations of this work can be summarised as follows: Sulphate ions seem to be more aggressive than chloride ions towards the primary passive film on 08X18H10T stainless steel. The results may indicate that it is more important to have a low concentration of sulphate ions than of chloride ions in secondary side water when the effects of chemical conditions on tube degradation are considered. The presence of chloride ions seems to weaken the detrimental effect of sulphate ions on the stability of oxide films growing on 08X18H10T stainless steel. No localised corrosion features of 08X18H10T stainless steel were detected in the voltammetric and impedance measurements in solutions containing up to 5000 ppb sulphates, chlorides or both of the anions. (authors)

  20. Microbial electricity generation enhances decabromodiphenyl ether (BDE-209) degradation.

    Science.gov (United States)

    Yang, Yonggang; Xu, Meiying; He, Zhili; Guo, Jun; Sun, Guoping; Zhou, Jizhong

    2013-01-01

    Due to environmental persistence and biotoxicity of polybrominated diphenyl ethers (PBDEs), it is urgent to develop potential technologies to remediate PBDEs. Introducing electrodes for microbial electricity generation to stimulate the anaerobic degradation of organic pollutants is highly promising for bioremediation. However, it is still not clear whether the degradation of PBDEs could be promoted by this strategy. In this study, we hypothesized that the degradation of PBDEs (e.g., BDE-209) would be enhanced under microbial electricity generation condition. The functional compositions and structures of microbial communities in closed-circuit microbial fuel cell (c-MFC) and open-circuit microbial fuel cell (o-MFC) systems for BDE-209 degradation were detected by a comprehensive functional gene array, GeoChip 4.0, and linked with PBDE degradations. The results indicated that distinctly different microbial community structures were formed between c-MFCs and o-MFCs, and that lower concentrations of BDE-209 and the resulting lower brominated PBDE products were detected in c-MFCs after 70-day performance. The diversity and abundance of a variety of functional genes in c-MFCs were significantly higher than those in o-MFCs. Most genes involved in chlorinated solvent reductive dechlorination, hydroxylation, methoxylation and aromatic hydrocarbon degradation were highly enriched in c-MFCs and significantly positively correlated with the removal of PBDEs. Various other microbial functional genes for carbon, nitrogen, phosphorus and sulfur cycling, as well as energy transformation process, were also significantly increased in c-MFCs. Together, these results suggest that PBDE degradation could be enhanced by introducing the electrodes for microbial electricity generation and by specifically stimulating microbial functional genes.

  1. Microbial electricity generation enhances decabromodiphenyl ether (BDE-209 degradation.

    Directory of Open Access Journals (Sweden)

    Yonggang Yang

    Full Text Available Due to environmental persistence and biotoxicity of polybrominated diphenyl ethers (PBDEs, it is urgent to develop potential technologies to remediate PBDEs. Introducing electrodes for microbial electricity generation to stimulate the anaerobic degradation of organic pollutants is highly promising for bioremediation. However, it is still not clear whether the degradation of PBDEs could be promoted by this strategy. In this study, we hypothesized that the degradation of PBDEs (e.g., BDE-209 would be enhanced under microbial electricity generation condition. The functional compositions and structures of microbial communities in closed-circuit microbial fuel cell (c-MFC and open-circuit microbial fuel cell (o-MFC systems for BDE-209 degradation were detected by a comprehensive functional gene array, GeoChip 4.0, and linked with PBDE degradations. The results indicated that distinctly different microbial community structures were formed between c-MFCs and o-MFCs, and that lower concentrations of BDE-209 and the resulting lower brominated PBDE products were detected in c-MFCs after 70-day performance. The diversity and abundance of a variety of functional genes in c-MFCs were significantly higher than those in o-MFCs. Most genes involved in chlorinated solvent reductive dechlorination, hydroxylation, methoxylation and aromatic hydrocarbon degradation were highly enriched in c-MFCs and significantly positively correlated with the removal of PBDEs. Various other microbial functional genes for carbon, nitrogen, phosphorus and sulfur cycling, as well as energy transformation process, were also significantly increased in c-MFCs. Together, these results suggest that PBDE degradation could be enhanced by introducing the electrodes for microbial electricity generation and by specifically stimulating microbial functional genes.

  2. Considerations for Metallographic Observation of Intergranular Attack in Steam Generator Tubes

    Energy Technology Data Exchange (ETDEWEB)

    Hur, Do Haeng; Choi, Myung Sik; Lee, Deok Hyun; Han, Jung Ho [Korea Atomic Enery Research Institute, Daejeon (Korea, Republic of)

    2013-10-15

    The extent and direction of the crazing depend on the type and direction of the applied stress to the corroded tube. In addition, it has been reported that IGA/IGP cannot be observed without proper etching techniques. This paper provides the metallographic characteristics of IGA in Alloy 600 steam generator tubes. The effect of applied stress on the morphology change of IGA area is discussed. In some cases, an IGA of steam generator tubes cannot be identified through etching techniques. It was found that an IGA tube was crazed along the grain boundaries into various types and directions through a deformation from applied stress. The direction and extent of the crazing depended on those of the applied stress. It was clearly shown that an IGA cannot be observed or misevaluated as an SCC. Therefore, special cautions should be paid during the destructive evaluation of the pulled-out tubes from operating steam generators.

  3. Gas generation from transuranic waste degradation: data summary and interpretation

    Energy Technology Data Exchange (ETDEWEB)

    Molecke, M.A.

    1979-12-01

    A comprehensive review of all applicable gas generation data resulting from the degradation of existing and potential forms of transuranic-contaminated wastes is presented. Extensive experimental studies have been performed under both realistic environmental conditions expected in the Waste Isolation Pilot Plant and overtest conditions. Degradation mechanisms investigated were radiolysis, thermal decomposition and dewatering, bacterial action, and chemical corrosion. Waste matrices studied include cellulosics, plastics, rubbers, organic composite, concrete-TRU ash, asphalt, process sludges, and mild steel. Measured gas generation rates are presented in terms of gas moles/year/drum of waste and in G(gas) values for radiolysis. The effects of multiple variables on gas generation are also described. 7 figures, 15 tables.

  4. Miniature, low-power X-ray tube using a microchannel electron generator electron source

    Science.gov (United States)

    Elam, Wm. Timothy (Inventor); Kelliher, Warren C. (Inventor); Hershyn, William (Inventor); DeLong, David P. (Inventor)

    2011-01-01

    Embodiments of the invention provide a novel, low-power X-ray tube and X-ray generating system. Embodiments of the invention use a multichannel electron generator as the electron source, thereby increasing reliability and decreasing power consumption of the X-ray tube. Unlike tubes using a conventional filament that must be heated by a current power source, embodiments of the invention require only a voltage power source, use very little current, and have no cooling requirements. The microchannel electron generator comprises one or more microchannel plates (MCPs), Each MCP comprises a honeycomb assembly of a plurality of annular components, which may be stacked to increase electron intensity. The multichannel electron generator used enables directional control of electron flow. In addition, the multichannel electron generator used is more robust than conventional filaments, making the resulting X-ray tube very shock and vibration resistant.

  5. Current Status on the Development of a Double Wall Tube Steam Generator

    Energy Technology Data Exchange (ETDEWEB)

    Nam, Ho Yun; Choi, Byoung Hae; Kim, Jong Man; Kim, Byung Ho

    2007-12-15

    A fast reactor, which uses sodium as a coolant, has a lot of merits as a next generation nuclear reactor. However, the possibility of a sodium-water reaction occurrence hinders the commercialization of this reactor. As one way to improve the reliability of a steam generator, a double-wall tube steam generator is being developed in GEN-4 program. In this report, the current state of the technical developments for a double-wall tube steam generator are reviewed and a future plan for the development of a double-wall tube steam generator is established. The current focuses of this research are an improvement of the heat transfer capability for a double-wall tube and the development of a proper leak detection method for the failure of a double-wall tube during a reactor operation. The ideal goal is an on-line leak detection of a double wall tube to prevent the sodium-water reaction. However, such a method is not developed as yet. An alternative method is being used to improve the reliability of a steam generator by performing a non-destructive test of a double wall tube during the refueling period of a reactor. In this method a straight double wall tube is employed to perform this test easily, but has a difficulty regarding an absorption of a thermal expansion of the used materials. If an on-line leak detection method is developed, the demerits of a straight double-wall tube are avoided by using a helical type double-wall tube, and the probability of a sodium-water reaction can be reduced to a level less than the design-based accident.

  6. UV-Irradiated Photocatalytic Degradation of Nitrobenzene by Titania Binding on Quartz Tube

    Directory of Open Access Journals (Sweden)

    Thou-Jen Whang

    2012-01-01

    Full Text Available A new method for UV-irradiated degradation of nitrobenzene by titania photocatalysts was proposed, titania nanoparticles were coated on a quartz tube through the introduction of tetraethyl orthosilicate into the matrix. The dependence of nitrobenzene photodegradation on pH, temperature, concentration, and air feeding was discussed, and the physical properties such as the activation energy, entropy, enthalpy, adsorption constant, and rate constant were acquired by conducting the reactions in a variety of experimental conditions. The optimum efficiency of the photodegradation with the nitrobenzene residue as low as 8.8% was achieved according to the experimental conditions indicated. The photodegradation pathways were also investigated through HPLC, GC/MS, ion chromatography (IC, and chemical oxygen demand (COD analyses.

  7. Microstructural degradation of boiler tube steels under long term exposure to high temperature

    Energy Technology Data Exchange (ETDEWEB)

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

    1996-12-31

    Thermal microstructural degradation was investigated by isothermal annealing of samples from boiler tube steels St 35.8, 15 Mo 3, 13 CrMo 44, 10 CrMo 9 10 and X20 CrMoV 12 1 in the temperature range 600-780 deg C for up to 2 000 h. Optical and scanning electron microscopy and hardness testing were used for characterising the micro structural changes and their time-temperature dependence. The results suggest a simple and consistent time-temperature dependence for all investigated materials, expected to apply also to long term service beyond the annealing time range of the present work. This would allow assessment of the in-service thermal exposure from the observed microstructure. A collection of micro graphs has been prepared for this purpose, to aid in classifying and evaluating the observed microstructural state in terms of isothermal exposure to high temperature. (orig.) (6 refs.)

  8. Steam generator degradation: Current mitigation strategies for controlling corrosion

    Energy Technology Data Exchange (ETDEWEB)

    Millett, P. [Electric Power Research Institute, Palo Alto, CA (United States)

    1997-02-01

    Steam Generator degradation has caused substantial losses of power generation, resulted in large repair and maintenance costs, and contributed to significant personnel radiation exposures in Pressurized Water Reactors (PWRs) operating throughout the world. EPRI has just published the revised Steam Generator Reference Book, which reviews all of the major forms of SG degradation. This paper discusses the types of SG degradation that have been experienced with emphasis on the mitigation strategies that have been developed and implemented in the field. SG degradation is presented from a world wide perspective as all countries operating PWRs have been effected to one degree or another. The paper is written from a US. perspective where the utility industry is currently undergoing tremendous change as a result of deregulation of the electricity marketplace. Competitive pressures are causing utilities to strive to reduce Operations and Maintenance (O&M) and capital costs. SG corrosion is a major contributor to the O&M costs of PWR plants, and therefore US utilities are evaluating and implementing the most cost effective solutions to their corrosion problems. Mitigation strategies developed over the past few years reflect a trend towards plant specific solutions to SG corrosion problems. Since SG degradation is in most cases an economic problem and not a safety problem, utilities can focus their mitigation strategies on their unique financial situation. Accordingly, the focus of R&D has shifted from the development of more expensive, prescriptive solutions (e.g. reduced impurity limits) to corrosion problems to providing the utilities with a number of cost effective mitigation options (e.g. molar ratio control, boric acid treatment).

  9. Laminar fluid flow and heat transfer in a fin-tube heat exchanger with vortex generators

    Energy Technology Data Exchange (ETDEWEB)

    Yanagihara, J.I.; Rodriques, R. Jr. [Polytechnic School of Univ. of Sao Paolo, Sao Paolo (Brazil). Dept. of Mechanical Engineering

    1996-12-31

    Development of heat transfer enhancement techniques for fin-tube heat exchangers has great importance in industry. In recent years, heat transfer augmentation by vortex generators has been considered for use in plate fin-tube heat exchangers. The present work describes a numerical investigation about the influence of delta winglet pairs of vortex generators on the flow structure and heat transfer of a plate fin-tube channel. The Navier-Stokes and Energy equations are solved by the finite volume method using a boundary-fitted coordinate system. The influence of vortex generators parameters such as position, angle of attack and aspect ratio were investigated. Local and global influences of vortex generators in heat transfer and flow losses were analyzed by comparison with a model using smooth fin. The results indicate great advantages of this type of geometry for application in plate fin-tube heat exchangers, in terms of large heat transfer enhancement and small pressure loss penalty. (author)

  10. Steam generator tubes integrity: In-service-inspection

    Energy Technology Data Exchange (ETDEWEB)

    Comby, R.J. [EDF/GDL, Saint Denis (France)

    1997-02-01

    The author`s approach to tube integrity is in terms of looking for flaws in tubes. The basis for this approach is that no simple rules can be fixed to adopt a universal inspection methodology because of various concepts related to experience, leak acceptance, leak before break approach, etc. Flaw specific management is probably the most reliable approach as a compromise between safety, availability and economic issues. In that case, NDE capabilities have to be in accordance with information required by structural integrity demonstration. The author discusses the types of probes which can be used to search for flaws in addition to the types of flaws which are being sought, with examples of specific analysis experiences. The author also discusses the issue of a reporting level as it relates to avoiding false calls, classifying faults, and allowing for automation in analysis.

  11. New Media: Engaging and Educating the YouTube Generation

    Directory of Open Access Journals (Sweden)

    Anu Vedantham

    2011-12-01

    Full Text Available Today's undergraduates are clearly comfortable as consumers of technology and new media—purchasing ring tones for their cell phones and tunes for their iPods, text-messaging from handheld devices, scanning and tinkering with photos, keeping up with their Facebook friends and watching viral YouTube videos, sometimes all simultaneously. We share examples of classroom assignments integrated with library support services that engage today's undergraduates with academic materials in a variety of course contexts. We discuss how specific arrangements of library learning spaces and the alignment of space and staffing can help undergraduate students succeed with new media projects for class assignments.

  12. Trapping Dirac fermions in tubes generated by two scalar fields

    CERN Document Server

    Casana, R; Martins, G V; Simas, F C

    2013-01-01

    In this work we consider $(1,1)-$dimensional resonant Dirac fermionic states on tube-like topological defects. The defects are formed by rings in $(2,1)$ dimensions, constructed with two scalar field $\\phi$ and $\\chi$, and embedded in the $(3,1)-$dimensional Minkowski spacetime. The tube-like defects are attained from a lagrangian density explicitly dependent with the radial distance $r$ relative to the ring axis and the radius and thickness of the its cross-section are related to the energy density. For our purposes we analyze a general Yukawa-like coupling between the topological defect and the fermionic field $\\eta F(\\phi,\\chi)\\bar\\psi\\psi$. With a convenient decomposition of the fermionic fields in left- and right- chiralities, we establish a coupled set of first order differential equations for the amplitudes of the left- and right- components of the Dirac field. After decoupling and decomposing the amplitudes in polar coordinates, the radial modes satisfy Schr\\"odinger-like equations whose eigenvalues a...

  13. French Regulatory practice and experience feedback on steam generator tube integrity

    Energy Technology Data Exchange (ETDEWEB)

    Sandon, G.

    1997-02-01

    This paper summarizes the way the French Safety Authority applies regulatory rules and practices to the problem of steam generator tube cracking in French PWR reactors. There are 54 reactors providing 80% of French electrical consumption. The Safety Authority closely monitors the performance of tubes in steam generators, and requires application of a program which deals with problems prior to the actual development of leakage. The actual rules regarding such performance are flexible, responding to the overall performance of operating steam generators. In addition there is an inservice inspection service to examine tubes during shutdown, and to monitor steam generators for leakage during operation, with guidelines for when generators must be pulled off line.

  14. Nano surface generation of grinding process using carbon nano tubes

    Indian Academy of Sciences (India)

    S Prabhu; B K Vinayagam

    2010-12-01

    Nano surface finish has become an important parameter in the semiconductor, optical, electrical and mechanical industries. The materials used in these industries are classified as difficult to machine materials such as ceramics, glasses and silicon wafers. Machining of these materials up to nano accuracy is a great challenge in the manufacturing industry. Finishing of micro components such as micro-moulds, micro-lenses and micro-holes need different processing techniques. Conventional finishing methods used so far become almost impossible or cumbersome. In this paper, a nano material especially multi wall carbon nano tube is used in the machining process like grinding to improve the surface characteristics from micro to nano level.

  15. Degradation and buckling of metal tubes under cyclic bending and external pressure

    Science.gov (United States)

    Corona, Edmundo

    The response and stability of long tubular components under bending and external pressure were investigated. The behavior of the structure under monotonic as well as cyclic bending was examined through combined experimental and analytical efforts. The experiments involved metal seamless tubes with diameter-to-thickness ratios in the range of 17 to 35. Long specimens were tested under combined bending and pressure in a specially developed test facility. Bending-pressure interaction collapse envelopes were first generated for monotonically increasing loading histories. The two loads were found to interact strongly through the ovalization of the cross section and the collapse envelopes to depend on the loading history followed. Cyclic bending under various curvature controlled and moment controlled histories was considered. The factors influencing the rate of accumulation of ovalization and the resulting instabilities were studied parametrically. Buckling under cyclic loads occurred when the ovalization of the tubes reached a critical value approximately equal to the critical value developed under the corresponding monotonically applied loads. The problem was analyzed numerically using kinematics which capture the ovalization of the cross section. The predicted response was found to be very sensitive to the elastic-plastic constitutive models used. This sensitivity was carefully analyzed using state-of-the-art models. In the case of cyclic loading histories, the hardening rules used in such models were found to play a pivotal role in the accuracy of the predictions. The reasons for this sensitivity were studied through a parallel investigation of the behavior of the material under cyclic loads.

  16. Lipase degradation of plasticized polyvinyl chloride endotracheal tube surfaces to create nanoscale features

    Science.gov (United States)

    Machado, Mary C; Webster, Thomas J

    2017-01-01

    Polyvinyl chloride (PVC) endotracheal tubes (ETTs) nanoetched with a fungal lipase have been shown to reduce bacterial growth and biofilm formation and could be an inexpensive solution to the complex problem of ventilator-associated pneumonia (VAP). Although bacterial growth and colonization on these nanoetched materials have been well characterized, little is known about the mechanism by which the fungal lipase degrades the PVC and, thus, alters its properties to minimize bacteria functions. This study used X-ray photoelectron spectroscopy (XPS) and attenuated total reflectance Fourier transform infrared spectroscopy (ATR-FTIR) to better describe the surface chemistry of both unetched and lipase nanoetched PVC ETT. ATR-FTIR analysis of the unetched and treated surfaces showed a similar presence of a plasticizer. This was confirmed by XPS analysis, which showed an increase of carbon and the presence of oxygen on both unetched and nanoetched surfaces. A quantitative comparison of the FTIR spectra revealed significant correlations (Pearson’s correlation, R=0.997 [R2=0.994, Pinfrared peaks due to the degradation of the plasticizer by the fungal lipase. In contrast, results from this study did demonstrate significantly increased nanoscale surface features on the lipase etched compared to non-etched PVC ETTs. This led to a change in surface energetics, which altered ion adsorption to the ETTs. Thus, these results showed that PVC surfaces nanoetched with a 0.1% lipase solution for 48 hours have no significant change on surface chemistry but do significantly increase nanoscale surface roughness and alters ion adsorption, which suggests that the unique properties of these materials, including their previously reported ability to decrease bacterial adhesion and growth, are due to the changes in the degree of the nanoscale roughness, not changes in their surface chemistry. PMID:28352177

  17. Generation of saffron volatiles by thermal carotenoid degradation.

    Science.gov (United States)

    Carmona, Manuel; Zalacain, Amaya; Salinas, M Rosario; Alonso, Gonzalo L

    2006-09-06

    Generation of volatiles by thermal treatments has been studied in saffron spice for two reasons: (a) to determine volatile profile changes during simulated aging processes and (b) to study the volatile generation pathway. During the aging process, while the amounts of C10 compounds such as safranal and HTCC increase, the amounts of C9 compounds such as isophorone and 2,6,6-trimethylcyclohexane-1,4-dione decrease. A new compound tentatively identified as 4,5,6,7-tetrahydro-7,7-dimethyl-5-oxo-3H-isobenzofuranone seems to play a very important role in the aging process. The importance of this compound, structurally similar to dihydroactindiolide, was also confirmed when the saffron volatile fraction was analyzed via the degradation of the linear chain of crocetin and crocetin esters and is reported for the first time in this paper. Thermal degradation studies of zeaxanthin, crocetin, and trans and cis crocetin esters isomers allowed us to propose different mechanisms which explain saffron volatile generation depending on the crocetin ester isomer structure.

  18. On the influence of manufacturing practices on the SCC behavior of Alloy 690 steam generator tubing

    Energy Technology Data Exchange (ETDEWEB)

    Doherty, P.E.; Doyle, D.M. [Babcock and Wilcox International Div., Cambridge, Ontario (Canada); Sarver, J.M.; Miglin, B.P. [Babcock and Wilcox Research Div., Alliance, OH (United States)

    1996-12-31

    Thermally treated (TT) Alloy 690 is the tubing materials of choice for replacement steam generators (RSGs) throughout the world. It is manufactured using a variety of processing methods with regards to melt practice and thermomechanical forming. Studies assessing the IGSCC resistance of Alloy 690 TT SG tubing have identified a variability in the corrosion performance of nominally identical alloys. While tubing of comparable bulk chemistry may exhibit variations in microchemistry as a result of different melt practice, the correlation between melt practice and SCC resistance is difficult to assess due to other contributing factors. The other contributing factors are identified in this investigation as microstructural features whose generation is dependent on features of particular strain-anneal forming methods by which SG tubes are fabricated. In this study the microstructural characteristics which appear to affect inservice corrosion performance of Alloy 690 TT SG tubes were evaluated. The studies included extensive microstructural examinations in addition to CERT tests performed on actual Alloy 690 TT nuclear SG tubing. The CERT test results indicate that Alloy 690 TT tubing processed at higher mill anneal temperatures display the highest degree of stress corrosion cracking (SCC) resistance. This observation is discussed with reference to carbide distributions, textural aspects and grain boundary orientation character.

  19. Multi-element eddy current probe. For inspecting steam generator tubes

    Energy Technology Data Exchange (ETDEWEB)

    Savin, E.; Sartre, B. [FRAMATOME, 92 - Paris-La-Defense (France); Placko, D.; Premel, D. [Ecole Nationale Superieure de Cachan, 94 (France)

    2000-10-01

    Framatome and the Ecole Normale Superieure de Cachan are developing a multi-element eddy current probe for inspecting steam generator tubes of 900 MWe PWR reactors. The device is intended to replace much slower rotating probes. Using its measurements, the conductivity image of any point in the tube can be reconstructed, thanks to a numerical, thanks to a numerical model, thus allowing diagnosis. The first trial results on mockups seem already competitive with those obtained using a rotary probe. (authors)

  20. Degradation of chlorophenol by in-situ electrochemically generated oxidant

    Institute of Scientific and Technical Information of China (English)

    丛燕青; 吴祖成; 叶倩; 谭天恩

    2004-01-01

    A novel in-situ electrochemical oxidation method was applied to the degradation of wastewater containing chlorophenol. Under oxygen sparging, the strong oxidant, hydrogen dioxide, could be in-situ generated through the reduction of oxygen on the surface of the cathode. The removal rate ofchlorophenol could be increased 149% when oxygen was induced in the electrochemical cell. The promotion factor was estimated to be about 82.63% according to the pseudo-first-order reaction rate constant (min-1). Important operating parameters such as current density, sparged oxygen rate were investigated. Higher sparged oxygen rate could improve the degradation of chlorophenol. To make full use of oxygen, however, sparged oxygen rate of 0.05 m3/h was adopted in this work. Oxidation-reduction potential could remarkably affect the generation of hydrogen peroxide. It was found that the removal rate of chlorophenol was not in direct proportion to the applied current density. The optimum current density was 3.5 mA/cm2 when initial chlorophenol concentration was 100 mg/L and sparged oxygen rate was 0.05 m3/h.

  1. Degradation of chlorophenol by in-situ electrochemically generated oxidant

    Institute of Scientific and Technical Information of China (English)

    丛燕青; 吴祖成; 叶倩; 谭天恩

    2004-01-01

    A novel in-situ electrochemical oxidation method was applied to the degradation of wastewater containing chlorophenol. Under oxygen sparging, the strong oxidant, hydrogen dioxide, could be in-situ generated through the reduction of oxygen on the surface of the cathode. The removal rate ofchlorophenol could be increased 149% when oxygen was induced in the electrochemical cell. The promotion factor was estimated to be about 82.63% according to the pseudo-first-order reaction rate constant (min-1). Important operating parameters such as current density, sparged oxygen rate were investigated.Higher sparged oxygen rate could improve the degradation of chlorophenol. To make full use of oxygen, however, sparged oxygen rate of 0.05 m3/h was adopted in this work. Oxidation-reduction potential could remarkably affect the generation of hydrogen peroxide. It was found that the removal rate of chlorophenol was not in direct proportion to the applied current density. The optimum current density was 3.5 mA/cm2 when initial chlorophenol concentration was 100 mg/L and sparged oxygen rate was 0.05 m3/h.

  2. Evaluation of sampling plans for in-service inspection of steam generator tubes. Volume 2, Comprehensive analytical and Monte Carlo simulation results for several sampling plans

    Energy Technology Data Exchange (ETDEWEB)

    Kurtz, R.J.; Heasler, P.G.; Baird, D.B. [Pacific Northwest Lab., Richland, WA (United States)

    1994-02-01

    This report summarizes the results of three previous studies to evaluate and compare the effectiveness of sampling plans for steam generator tube inspections. An analytical evaluation and Monte Carlo simulation techniques were the methods used to evaluate sampling plan performance. To test the performance of candidate sampling plans under a variety of conditions, ranges of inspection system reliability were considered along with different distributions of tube degradation. Results from the eddy current reliability studies performed with the retired-from-service Surry 2A steam generator were utilized to guide the selection of appropriate probability of detection and flaw sizing models for use in the analysis. Different distributions of tube degradation were selected to span the range of conditions that might exist in operating steam generators. The principal means of evaluating sampling performance was to determine the effectiveness of the sampling plan for detecting and plugging defective tubes. A summary of key results from the eddy current reliability studies is presented. The analytical and Monte Carlo simulation analyses are discussed along with a synopsis of key results and conclusions.

  3. 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.

  4. Determination of thermal characteristics of combustion products of fire-tube heat generator with flow turbulator

    Directory of Open Access Journals (Sweden)

    Lukjanov Alexander V.

    2014-12-01

    Full Text Available Boiler construction is one of the major industries of any state. The aim is to determine the effect of the turbulator on the intensity of heat transfer in the convective part of the fire-tube heat generator of domestic production. The improvement of convective heating surfaces is one of the ways to increase the energy efficiency of the fire-tube heat generator. Since model of the process of heat transfer of gas flow in the convective tubes is multifactorial and does not have clear analytical solution at present, the study of process above is carried out using the experimental method. The results of applying the flow turbulator as a broken tape in the fire-tube heat generator of KV-GM type are presented. On their basis it can be concluded about increasing of heat transfer in convective part of the unit. The use of efficient, reliable, easy to manufacture, relatively inexpensive turbulator in domestic fire-tube heat generators will allow to increase their energy conversion efficiency and reduce fuel consumption, which will have a positive economic effect.

  5. Entropy Generation in Flow of Highly Concentrated Non-Newtonian Emulsions in Smooth Tubes

    Directory of Open Access Journals (Sweden)

    Rajinder Pal

    2014-10-01

    Full Text Available Entropy generation in adiabatic flow of highly concentrated non-Newtonian emulsions in smooth tubes of five different diameters (7.15–26.54 mm was investigated experimentally. The emulsions were of oil-in-water type with dispersed-phase concentration (Φ ranging from 59.61–72.21% vol. The emulsions exhibited shear-thinning behavior in that the viscosity decreased with the increase in shear rate. The shear-stress (τ versus shear rate (˙γ data of emulsions could be described well by the power-law model: τ=K˙γn. The flow behavior index n was less than 1 and it decreased sharply with the increase in Φ whereas the consistency index K increased rapidly with the increase in Φ . For a given emulsion and tube diameter, the entropy generation rate per unit tube length increased linearly with the increase in the generalized Reynolds number ( Re_n on a log-log scale. For emulsions with Φ ≤65.15 % vol., the entropy generation rate decreased with the increase in tube diameter. A reverse trend in diameter-dependence was observed for the emulsion with Φ of 72.21% vol. New models are developed for the prediction of entropy generation rate in flow of power-law emulsions in smooth tubes. The experimental data shows good agreement with the proposed models.

  6. Characteristics of draft tube gas-liquid-solid fluidized-bed bioreactor with immobilized living cells for phenol degradation.

    Science.gov (United States)

    Fan, L S; Fujie, K; Long, T R; Tang, W T

    1987-09-01

    Biological phenol degradation in a draft tube gas-liquid-solid fluidized bed (DTFB) bioreactor containing a mixed culture immobilized on spherical activated carbon particles was investigated. The characteristics of biofilms including the biofilm dry density and thickness, the volumetric oxygen mass transfer coefficient, and the phenol removal rates under different operating conditions in the DTFB were evaluated. A phenol degradation rate as high as 18 kg/m(3)-day with an effluent phenol concentration less than 1 g/m(3) was achieved, signifying the high treatment efficiency of using a DTFB.

  7. Transmit-receive eddy current probes for defect detection and sizing in steam generator tubes

    Energy Technology Data Exchange (ETDEWEB)

    Obrutsky, L.S.; Cecco, V.S.; Sullivan, S.P. [Atomic Energy of Canada Limited, Chalk River, Ontario (Canada)

    1997-02-01

    Inspection of steam generator tubes in aging Nuclear Generating Stations is increasingly important. Defect detection and sizing, especially in defect prone areas such as the tubesheet, support plates and U-bend regions, are required to assess the fitness-for-service of the steam generators. Information about defect morphology is required to address operational integrity issues, i.e., risk of tube rupture, number of tubes at risk, consequential leakage. A major challenge continues to be the detection and sizing of circumferential cracks. Utilities around the world have experienced this type of tube failure. Conventional in-service inspection, performed with eddy current bobbin probes, is ineffectual in detecting circumferential cracks in tubing. It has been demonstrated in CANDU steam generators, with deformation, magnetite and copper deposits that multi-channel probes with transmit-receive eddy current coils are superior to those using surface impedance coils. Transmit-receive probes have strong directional properties, permitting probe optimization according to crack orientation. They are less sensitive to lift-off noise and magnetite deposits and possess good discrimination to internal defects. A single pass C3 array transmit-receive probe developed by AECL can detect and size circumferential stress corrosion cracks as shallow as 40% through-wall. Since its first trial in 1992, it has been used routinely for steam generator in-service inspection of four CANDU plants, preventing unscheduled shutdowns due to leaking steam generator tubes. More recently, a need has surfaced for simultaneous detection of both circumferential and axial cracks. The C5 probe was designed to address this concern. It combines transmit-receive array probe technology for equal sensitivity to axial and circumferential cracks with a bobbin probe for historical reference. This paper will discuss the operating principles of transmit-receive probes, along with inspection results.

  8. Generation of Cold Argon Plasma Jet at the End of Flexible Plastic Tube

    CERN Document Server

    Kostov, Konstantin G; Prysiazhnyi, Vadym

    2014-01-01

    This brief communication reports a new method for generation of cold atmospheric pressure plasma jet at the downstream end of a flexible plastic tube. The device consists of a small chamber where dielectric barrier discharge (DBD) is ignited in Argon. The discharge is driven by a conventional low frequency AC power supply. The exit of DBD reactor is connected to a commercial flexible plastic tube (up to 4 meters long) with a thin floating Cu wire inside. Under certain conditions an Ar plasma jet can be extracted from the downstream tube end and there is no discharge inside the plastic tube. The jet obtained by this method is cold enough to be put in direct contact with human skin without electric shock and can be used for medical treatment and decontamination.

  9. Studies on an improved indigenous pressure wave generator and its testing with a pulse tube cooler

    Science.gov (United States)

    Jacob, S.; Karunanithi, R.; Narsimham, G. S. V. L.; Kranthi, J. Kumar; Damu, C.; Praveen, T.; Samir, M.; Mallappa, A.

    2014-01-01

    Earlier version of an indigenously developed Pressure Wave Generator (PWG) could not develop the necessary pressure ratio to satisfactorily operate a pulse tube cooler, largely due to high blow by losses in the piston cylinder seal gap and due to a few design deficiencies. Effect of different parameters like seal gap, piston diameter, piston stroke, moving mass and the piston back volume on the performance is studied analytically. Modifications were done to the PWG based on analysis and the performance is experimentally measured. A significant improvement in PWG performance is seen as a result of the modifications. The improved PWG is tested with the same pulse tube cooler but with different inertance tube configurations. A no load temperature of 130 K is achieved with an inertance tube configuration designed using Sage software. The delivered PV power is estimated to be 28.4 W which can produce a refrigeration of about 1 W at 80 K.

  10. Loss of feed flow, steam generator tube rupture and steam line break thermohydraulic experiments

    Energy Technology Data Exchange (ETDEWEB)

    Mendler, O J; Takeuchi, K; Young, M Y

    1986-10-01

    The Westinghouse Model Boiler No. 2 (MB-2) steam generator test model at the Engineering Test Facility in Tampa, Florida, was reinstrumented and modified for performing a series of tests simulating steam generator accident transients. The transients simulated were: loss of feed flow, steam generator tube rupture, and steam line break events. This document presents a description of (1) the model boiler and the associated test facility, (2) the tests performed, and (3) the analyses of the test results.

  11. Considerations for metallographic observation of intergranular attack in alloy 600 steam generator tubes

    Energy Technology Data Exchange (ETDEWEB)

    Hur, Do Haeng; Choi, Myung Sik; Lee, Deok Hyun; Han, Jung Ho [Korea Atomic Energy Research Institute, Daejeon (Korea, Republic of)

    2015-12-15

    This technical note provides some considerations for the metallographic observation of intergranular attack (IGA) in Alloy 600 steam generator tubes. The IGA region was crazed along the grain boundaries through a deformation by an applied stress. The direction and extent of the crazing depended on those of the applied stress. It was found that an IGA defect can be misevaluated as a stress corrosion crack. Therefore, special caution should be taken during the destructive examination of the pulled-out tubes from operating steam generators.

  12. Experimental residual stress evaluation of hydraulic expansion transitions in Alloy 690 steam generator tubing

    Energy Technology Data Exchange (ETDEWEB)

    McGregor, R.; Doherty, P. [Babcock and Wilcox International, Cambridge, Ontario (Canada); Hornbach, D. [Lambda Research Inc., Cincinnati, OH (United States); Abdelsalam, U. [McMaster Univ., Hamilton, Ontario (Canada)

    1995-12-31

    Nuclear Steam Generator (SG) service reliability and longevity have been seriously affected worldwide by corrosion at the tube-to-tubesheet joint expansion. Current SG designs for new facilities and replacement projects enhance corrosion resistance through the use of advanced tubing materials and improved joint design and fabrication techniques. Here, transition zones of hydraulic expansions have undergone detailed experimental evaluation to define residual stress and cold-work distribution on and below the secondary-side surface. Using X-ray diffraction techniques, with supporting finite element analysis, variations are compared in tubing metallurgical condition, tube/pitch geometry, expansion pressure, and tube-to-hole clearance. Initial measurements to characterize the unexpanded tube reveal compressive stresses associated with a thin work-hardened layer on the outer surface of the tube. The gradient of cold-work was measured as 3% to 0% within .001 inch of the surface. The levels and character of residual stresses following hydraulic expansion are primarily dependent on this work-hardened surface layer and initial stress state that is unique to each tube fabrication process. Tensile stresses following expansion are less than 25% of the local yield stress and are found on the transition in a narrow circumferential band at the immediate tube surface (< .0002 inch/0.005 mm depth). The measurements otherwise indicate a predominance of compressive stresses on and below the secondary-side surface of the transition zone. Excellent resistance to SWSCC initiation is offered by the low levels of tensile stress and cold-work. Propagation of any possible cracking would be deterred by the compressive stress field that surrounds this small volume of tensile material.

  13. Critical heat flux prediction for water boiling in vertical tubes of a steam generator

    Energy Technology Data Exchange (ETDEWEB)

    Payan-Rodriguez, L.A.; Gallegos-Munoz [Departmet of Mechanical Engineering, University of Guanajuato, Av. Tampico No. 912 Salamanca (Mexico); Porras-Loaiza, G.L. [Institute for Electrical Researches, Av. Reforma No. 113, Temixco (Mexico); Picon-Nunez [Institute for Scientific Research, University of Guanajuato, Lascurain de Retana No. 5, Guanajuato (Mexico)

    2005-02-01

    This paper presents a methodology for the prediction of the critical heat flux (CHF) for the boiling of water in vertical tubes operating under typical conditions found in steam generators. At the furnace, the water flows through long vertical tubes under an axially non-uniform heat flux and with relatively low mass fluxes. This fact causes that the recent theories and correlations, which have been developed for conditions typically found in nuclear reactors, cannot be directly applied for the prediction of the CHF in the furnace tubes. In this context, the mechanistic theories focused into the CHF prediction have proved their usefulness to predict CHF avoiding the use of correlations and experimental constants. Hence, in order to assist the CHF problem in steam generators, the sublayer dryout theory, initially formulated for CHF in vertical tubes uniformly heated, is extended by combining it with the shape factor method (F-factor), to account for the effects of the axially non-uniform heat flux distribution. The critical wall temperature (CWT) of the tubes is calculated from CHF data. The reliability of the modified theory for the CHF prediction is tested by comparing CWT results against measured data from a steam generator of a power plant. Good consistency and approximation is found between predicted and measured data. (authors)

  14. Synthesis of degradable poly(L-lactide-co-ethylene glycol) porous tubes by liquid-liquid centrifugal casting for use as nerve guidance channels.

    Science.gov (United States)

    Goraltchouk, Alex; Freier, Thomas; Shoichet, Molly S

    2005-12-01

    Biodegradable nerve guidance channels are advantageous, obviating the need for their removal after regeneration; however, most channels lack the appropriate mechanical properties for soft tissue implantation and/or degrade too quickly, resulting in reduced regeneration and necessitating the need for the design of polymers with tunable degradation profiles and mechanical properties. We designed a series of biodegradable polymeric hydrogel tubes consisting of L-lactide (LLA) and polyethylene glycol (PEG) where both the ratio of LLA to PEG and PEG molar mass were varied. By adjusting the PEG:LLA ratio and the molecular weight of the PEG oligomer we were able to control degradation and mechanical properties of our polymers. By incorporating methacrylate (MA) groups on both termini of the linear oligomers, porous tubes were synthesized by a redox-initiated free radical mechanism during a liquid-liquid centrifugal casting process. The tube wall had a bead-like morphology, as determined by SEM, which was reminiscent of previous porous hydrogel tubes synthesized by the same method. Tubes swelled with degradation to 160 vol%, or 640 wt%, and an increased radius calculated at 1.26 times. Those tubes with greater PEG content and PEG molar mass degraded faster than those with greater LLA content, as was expected. Interestingly, the wall morphology changed with degradation to a fiber-like structure and the mechanical properties decreased with degradation. By correlating the accelerated degradation study to a physiologic one, these porous hydrogel tubes were stable for an equivalent of 1.5 months, after which the mechanical properties began to deteriorate. This study demonstrates how porous hydrogel tubes can be designed to meet tissue regeneration criteria by tuning the formulation chemistry and specifically how the ratio of hydrophobic/crystalline LLA and hydrophilic/amorphous PEG impact tube properties.

  15. Generation of droplets via oscillations of a tapered capillary tube filled with low-viscosity liquids

    Science.gov (United States)

    Mao, Xinyu; Zhang, Lei; Zhao, Zhenhao; Lin, Feng

    2017-06-01

    Droplet formation via the oscillations of a tapered capillary tube is experimentally and numerically investigated using incompressible, low-viscosity Newtonian liquids. As in many other common methods of droplet generation, this technique features a transient flow that is directed out of a nozzle. However, due to the interactions of the oscillations, the tube, and the fluids, the flow rate upstream of the nozzle cannot be directly obtained. In this study, the motion of the tube is measured under the activation of a specific waveform, and the flow inside the tube and drop formation are further numerically studied using a non-inertial reference system in which the tube is stationary. The mechanism of ejection is quantitatively explained by analyzing the temporal variation in the velocity and pressure distributions inside the tube. The dynamics of drop formation, the drop velocity, and the drop radius are studied as functions of the dimensionless groups that govern the problem, including the Ohnesorge number Oh, the Weber number We, the gravitational Bond number G, and various length scale ratios. The results show that droplets are generated due to the inertia of the liquid and velocity amplification in the tapered section. By influencing the balance between the viscous effect and inertial effect of the liquid along the entire tube, the length scale ratios affect the evolution of the transient flow at the nozzle and eventually influence the drop radius and velocity. For liquids with viscosities close to that of pure water, the critical Reynolds number, at which a drop can be generated, linearly depends on the Z number (the reciprocal of Oh) at the nozzle.

  16. Evaluation of a main steam line break with induced, multiple tube ruptures: A comparison of NUREG 1477 (Draft) and transient methodologies Palo Verde Nuclear Generating Station

    Energy Technology Data Exchange (ETDEWEB)

    Parrish, K.R.

    1995-09-01

    This paper presents the approach taken to analyze the radiological consequences of a postulated main steam line break event, with one or more tube ruptures, for the Palo Verde Nuclear Generating Station. The analysis was required to support the restart of PVNGS Unit 2 following the steam generator tube rupture event on March 14, 1993 and to justify continued operation of Units 1 and 3. During the post-event evaluation, the NRC expressed concern that Unit 2 could have been operating with degraded tubes and that similar conditions could exist in Units 1 and 3. The NRC therefore directed that a safety assessment be performed to evaluate a worst case scenario in which a non-isolable main steam line break occurs inducing one or more tube failures in the faulted steam generator. This assessment was to use the generic approach described in NUREG 1477, Voltage-Based Interim Plugging Criteria for Steam Generator Tubes - Task Group Report. An analysis based on the NUREG approach was performed but produced unacceptable results for off-site and control room thyroid doses. The NUREG methodology, however, does not account for plant thermal-hydraulic transient effects, system performance, or operator actions which could be credited to mitigate dose consequences. To deal with these issues, a more detailed analysis methodology was developed using a modified version of the Combustion Engineering Plant Analysis Code, which examines the dose consequences for a main steam line break transient with induced tube failures for a spectrum equivalent to 1 to 4 double ended guillotine U-tube breaks. By incorporating transient plant system responses and operator actions, the analysis demonstrates that the off-site and control room does consequences for a MSLBGTR can be reduced to acceptable limits. This analysis, in combination with other corrective and recovery actions, provided sufficient justification for continued operation of PVNGS Units 1 and 3, and for the subsequent restart of Unit 2.

  17. Prediction of structural integrity of steam generator tubes under severe accident conditions

    Energy Technology Data Exchange (ETDEWEB)

    Majumdar, S. [Argonne National Lab., IL (United States)

    1999-11-01

    Available models for predicting failure of flawed and unflawed steam generator tubes under normal operating and design-basis accident conditions are reviewed. These rate-independent flow stress models are inadequate for predicting failure of steam generator tubes under severe accident conditions because the temperature of the tubes during such accidents can reach as high as 800 C where creep effects become important. Therefore, a creep rupture model for predicting failure was developed and validated by tests on unflawed and flawed specimens containing axial and circumferential flaws and loaded by constant as well as ramped temperature and pressure loadings. Finally, tests were conducted using pressure and temperature histories that are calculated to occur during postulated severe accidents. In all cases, the creep rupture model predicted the failure temperature and time more accurately than the flow stress models. (orig.)

  18. Steam generators regulatory practices and issues in Spain

    Energy Technology Data Exchange (ETDEWEB)

    Mendoza, C.; Castelao, C.; Ruiz-Colino, J.; Figueras, J.M. [CSN, Madrid (Spain)

    1997-02-01

    This paper presents the actual status of Spanish Steam Generator tubes, actions developed by PWR plant owners and submitted to CSN, and regulatory activities related to tube degradation mechanisms analysis; NDT tube inspection techniques; tube, tubesheet and TSPs integrity studies; tube plugging/repair criteria; preventive and corrective measures including whole SGs replacement; tube leak measurement methods and other operational aspects.

  19. Study of thermal influence on tubes due to sodium-water reactions in LMFBR steam generator

    Energy Technology Data Exchange (ETDEWEB)

    Hamada, H.; Kurihara, A.; Nishimura, M. [Japan Nuclear Cycle Development Institute, Ibaraki (Japan)

    2004-07-01

    A study of thermal influence on heat-transfer tubes in sodium-water reactions is carried out to evaluate the tube rupture due to overheating in the water leak accident of an LMFBR steam generator (SG). By assuming the sodium-water reaction jet to be a two-phase flow that consists of sodium and hydrogen, the heat-transfer characteristics are examined and a simple model of effective heat-transfer coefficient (HTC) is proposed for the safety evaluation of the SG. Comparison of the model with experimental data leads to the following conclusions: An upper limit exists in the HTC between reaction jet and tube wall, and it is equivalent in approximation to the HTC of single-phase sodium flow. The HTC can be written in simple form as functions of the HTC of single-phase sodium flow, void fraction and temperatures of sodium, hydrogen and tube wall. Hydrogen provides negligible heating effect, so that the apparent HTC would decrease with increase of the hydrogen temperature that can readily surpass that of sodium. The outer-surface temperature of tube wall would not rise so high beyond the temperature of sodium that is excellent in heat-transfer characteristics, even if tube wall is exposed to the high-temperature hydrogen. The transient heat conduction analysis with the mean value of the data can appropriately evaluate the outer-surface temperature of tube wall by the metallographic observation, while the analysis with the maximum value can conservatively evaluate the tube wall temperature. (authors)

  20. Autonomous generation of a thermoacoustic solitary wave in an air-filled tube

    Science.gov (United States)

    Shimizu, Dai; Sugimoto, Nobumasa

    2016-10-01

    Experiments are performed to demonstrate the autonomous generation of an acoustic solitary wave in an air-filled, looped tube with an array of Helmholtz resonators. The solitary wave is generated spontaneously due to thermoacoustic instability by a pair of stacks installed in the tube and subject to a temperature gradient axially. No external drivers are used to create initial disturbances. Once the solitary wave is generated, it keeps on propagating to circulate along the loop endlessly. The stacks, which are made of ceramics and of many pores of square cross section, are placed in the tube diametrically on exactly the opposite side of the loop, and they are sandwiched by hot and cold (ambient) heat exchangers. When the temperature gradient along both stacks is appropriate, pulses of smooth profiles are generated and propagated in both directions of the tube. From good agreements of not only the pressure profile measured but also the propagation speed with the theory, the pulse is identified as the acoustic solitary wave, and it can be called thermoacoustic solitary wave or thermoacoustic soliton corresponding to the soliton solution of the K-dV equation in one limit.

  1. Principal-Generated YouTube Video as a Method of Improving Parental Involvement

    Science.gov (United States)

    Richards, Joey

    2013-01-01

    The purpose of this study was to evaluate the involvement level of parents and reveal whether principal-generated YouTube videos for regular communication would enhance levels of parental involvement at one North Texas Christian Middle School (pseudonym). The following questions guided this study: 1. What is the beginning level of parental…

  2. Susceptibility of steam generator tubes in secondary conditions: Effects of lead and sulphate

    Energy Technology Data Exchange (ETDEWEB)

    Gomez Briceno, D.; Garcia, M.S.; Castano, M.L.; Lancha, A.M. [CIEMAT, Madrid (Spain)

    1997-02-01

    IGA/SCC on the secondary side of steam generators is increasing every year, and represents the cause of some steam generator replacements. Until recently, caustic and acidic environments have been accepted as causes of IGA/SCC, particulary in certain environments: in sludge pile on the tube sheet; at support crevices; in free span. Lead and sulfur have been identified as significant impurities. Present thoughts are that some IGA/SCC at support crevices may have occurred in nearly neutral or mildly alkaline environments. Here the authors present experimental work aimed at studying the influence of lead and sulfur on the behaviour of steam generator tube alloys in different water environments typical of steam generators. Most test results ran for at least 2000 hours, and involved visual and detailed surface analysis during and following the test procedures.

  3. Influence of sodium deposits in steam generator tubes on remote field eddy current signals

    Energy Technology Data Exchange (ETDEWEB)

    Thirunavukkarasu, S. [EMSI Section, NDE Division, Metallurgy and Materials Group, Indira Gandhi Centre for Atomic Research, Kalpakkam 603 102, Tamil Nadu (India); Rao, B.P.C. [EMSI Section, NDE Division, Metallurgy and Materials Group, Indira Gandhi Centre for Atomic Research, Kalpakkam 603 102, Tamil Nadu (India)], E-mail: bpcrao@igcar.gov.in; Vaidyanathan, S.; Jayakumar, T.; Raj, Baldev [EMSI Section, NDE Division, Metallurgy and Materials Group, Indira Gandhi Centre for Atomic Research, Kalpakkam 603 102, Tamil Nadu (India)

    2008-04-15

    The presence of sodium deposits in defective regions of steam generator (SG) tubes of fast-breeder reactors is expected to influence the remote field eddy current (RFEC) signals. By exposing five SG tubes having uniform wall loss grooves to a sodium environment in a specially designed test vessel, changes in the shape of RFEC signals were observed and it was possible to approximate the volume of sodium deposited in defects. An invariant signal parameter was determined for quantitative characterization of defects despite the presence of sodium in the defects.

  4. Simple evaluations of fluid-induced vibrations for steam generator tube arrays in advanced marine reactors (MRX, DRX)

    Energy Technology Data Exchange (ETDEWEB)

    Saito, Kazuo [Ishikawajima-Harima Heavy Industries Co., Ltd., Tokyo (Japan); Ishida, Toshihisa [Japan Atomic Energy Research Inst., Tokai, Ibaraki (Japan). Tokai Research Establishment

    2001-06-01

    Advanced Marine Reactor (MRX) and Deep Sea Research Reactor (DRX) are the integral-type PWR, and the steam generators are installed in the reactor vessels. Steam generators are of the once-through, helical-coil tube types. Heat transfer tubes surround inner shroud in annular space of the reactor vessel. Flow-induced vibrations are calculated by simple methods, and the arrangement of tube support structures are evaluated. (author)

  5. Laser cleaning of steam generator tubing based on acoustic emission technology

    Energy Technology Data Exchange (ETDEWEB)

    Hou, Su-xia; Luo, Ji-jun; Shen, Tao; Li, Ru-song [Xi' an Hi-Tech Institute, Xi' an (China)

    2015-12-15

    As a physical method, laser cleaning technology in equipment maintenance will be a good prospect. The experimental apparatus for laser cleaning of heat tubes in the steam generator was designed according to the results of theoretical analysis. There are two conclusions; one is that laser cleaning technology is attached importance to traditional methods. Which has advantages in saving on much manpower and material resource and it is a good cleaning method for heat tubes. The other is that the acoustic emission signal includes lots of information on the laser cleaning process, which can be used as real-time monitoring in laser cleaning processes. When the laser acts for 350 s, 100 % contaminants of heat tubes is cleaned off, and the sensor only receives weak AE signal at that time.

  6. Heat Transfer Enhancement for Finned-Tube Heat Exchangers with Vortex Generators: Experimental and Numerical Results

    Energy Technology Data Exchange (ETDEWEB)

    O' Brien, James Edward; Sohal, Manohar Singh; Huff, George Albert

    2002-08-01

    A combined experimental and numerical investigation is under way to investigate heat transfer enhancement techniques that may be applicable to large-scale air-cooled condensers such as those used in geothermal power applications. The research is focused on whether air-side heat transfer can be improved through the use of finsurface vortex generators (winglets,) while maintaining low heat exchanger pressure drop. A transient heat transfer visualization and measurement technique has been employed in order to obtain detailed distributions of local heat transfer coefficients on model fin surfaces. Pressure drop measurements have also been acquired in a separate multiple-tube row apparatus. In addition, numerical modeling techniques have been developed to allow prediction of local and average heat transfer for these low-Reynolds-number flows with and without winglets. Representative experimental and numerical results presented in this paper reveal quantitative details of local fin-surface heat transfer in the vicinity of a circular tube with a single delta winglet pair downstream of the cylinder. The winglets were triangular (delta) with a 1:2 height/length aspect ratio and a height equal to 90% of the channel height. Overall mean fin-surface Nusselt-number results indicate a significant level of heat transfer enhancement (average enhancement ratio 35%) associated with the deployment of the winglets with oval tubes. Pressure drop measurements have also been obtained for a variety of tube and winglet configurations using a single-channel flow apparatus that includes four tube rows in a staggered array. Comparisons of heat transfer and pressure drop results for the elliptical tube versus a circular tube with and without winglets are provided. Heat transfer and pressure-drop results have been obtained for flow Reynolds numbers based on channel height and mean flow velocity ranging from 700 to 6500.

  7. Fluid-Structure Interaction Effects Modeling for the Modal Analysis of a Steam Generator Tube Bundle

    Energy Technology Data Exchange (ETDEWEB)

    Sigrist, J.F. [DCNS Prop, Serv Tech et Sci, F-44620 La Montagne, (France); Broc, D. [CEA Saclay, Serv Etud Mecan et Sism, F-91191 Gif Sur Yvette, (France)

    2009-07-01

    Seismic analysis of steam generator is of paramount importance in the safety assessment of nuclear installations. These analyses require, in particular, the calculation of frequency, mode shape, and effective modal mass of the system Eigenmodes. As fluid-structure interaction effects can significantly affect the dynamic behavior of immersed structures, the numerical modeling of the steam generator has to take into account FSI. A complete modeling of heat exchangers (including pressure vessel, tubes, and fluid) is not accessible to the engineer for industrial design studies. In the past decades, homogenization methods have been studied and developed in order to model tubes and fluid through an equivalent continuous media, thus avoiding the tedious task to mesh all structure and fluid sub-domains within the tube bundle. Few of these methods have nonetheless been implemented in industrial finite element codes. In a previous paper (Sigrist, 2007, 'Fluid-Structure Interaction Effects Modeling for the Modal Analysis of a Nuclear Pressure Vessel', J. Pressure Vessel Technol., 123, p. 1-6), a homogenization method has been applied to an industrial case for the modal analysis of a nuclear rector with internal structures and coupling effects modeling. The present paper aims at investigating the extension of the proposed method for the dynamic analysis of tube bundles with fluid-structure interaction modeling. The homogenization method is compared with the classical coupled method in terms of eigenfrequencies, Eigenmodes, and effective modal masses. (authors)

  8. Optimization of cavitation venturi tube design for pico and nano bubbles generation

    Institute of Scientific and Technical Information of China (English)

    Xiong Yu; Peng Felicia⇑

    2015-01-01

    Hydrodynamic cavitaion venturi tube technique is used for pico and nano bubble generations in coal column flotation. In order to determine the optimal design of hydrodynamic cavitation venture tube for pico and nano bubble generation, a four-factor three-level Central Composite Design of Experimental was conducted for investigating four important design parameters of cavitation venturi tube governing the median size and the volume of pico and nano bubbles. The test results showed that maximum volume of pico and nano bubbles, 65–75%, and minimum mean pico and nano bubble size, 150–240 nm, were achieved at the medium ratio of the diameter of outlet of the venturi-tube and diam-eter of throat (3–4), medium outlet angle (11–13?), high inlet angle (26–27?) and high ratio of the length of the throat and the diameter of throat (2.3–3). Study the effects of the producing pico and nano bubbles on fine coal flotation was performed in a 5 cm diameter 260 cm height flotation column. The optimal percentage of pico and nano bubbles was about 70%, which produced maximum combustible material recovery of 86%with clean coal ash content of 11.7%.

  9. Risk assessment of severe accident-induced steam generator tube rupture

    Energy Technology Data Exchange (ETDEWEB)

    NONE

    1998-03-01

    This report describes the basis, results, and related risk implications of an analysis performed by an ad hoc working group of the U.S. Nuclear Regulatory Commission (NRC) to assess the containment bypass potential attributable to steam generator tube rupture (SGTR) induced by severe accident conditions. The SGTR Severe Accident Working Group, comprised of staff members from the NRC`s Offices of Nuclear Reactor Regulation (NRR) and Nuclear Regulatory Research (RES), undertook the analysis beginning in December 1995 to support a proposed steam generator integrity rule. The work drew upon previous risk and thermal-hydraulic analyses of core damage sequences, with a focus on the Surry plant as a representative example. This analysis yielded new results, however, derived by predicting thermal-hydraulic conditions of selected severe accident scenarios using the SCDAP/RELAP5 computer code, flawed tube failure modeling, and tube failure probability estimates. These results, in terms of containment bypass probability, form the basis for the findings presented in this report. The representative calculation using Surry plant data indicates that some existing plants could be vulnerable to containment bypass resulting from tube failure during severe accidents. To specifically identify the population of plants that may pose a significant bypass risk would require more definitive analysis considering uncertainties in some assumptions and plant- and design-specific variables. 46 refs., 62 figs., 37 tabs.

  10. Risk assessment of severe accident-induced steam generator tube rupture

    Energy Technology Data Exchange (ETDEWEB)

    NONE

    1998-03-01

    This report describes the basis, results, and related risk implications of an analysis performed by an ad hoc working group of the U.S. Nuclear Regulatory Commission (NRC) to assess the containment bypass potential attributable to steam generator tube rupture (SGTR) induced by severe accident conditions. The SGTR Severe Accident Working Group, comprised of staff members from the NRC`s Offices of Nuclear Reactor Regulation (NRR) and Nuclear Regulatory Research (RES), undertook the analysis beginning in December 1995 to support a proposed steam generator integrity rule. The work drew upon previous risk and thermal-hydraulic analyses of core damage sequences, with a focus on the Surry plant as a representative example. This analysis yielded new results, however, derived by predicting thermal-hydraulic conditions of selected severe accident scenarios using the SCDAP/RELAP5 computer code, flawed tube failure modeling, and tube failure probability estimates. These results, in terms of containment bypass probability, form the basis for the findings presented in this report. The representative calculation using Surry plant data indicates that some existing plants could be vulnerable to containment bypass resulting from tube failure during severe accidents. To specifically identify the population of plants that may pose a significant bypass risk would require more definitive analysis considering uncertainties in some assumptions and plant- and design-specific variables. 46 refs., 62 figs., 37 tabs.

  11. Ultrasonic inspection of steam-generator tube axial cracking using Lamb wave

    Energy Technology Data Exchange (ETDEWEB)

    Park, Jae Seok

    2007-02-15

    In this study, the interaction of Lamb wave propagating thin tube structure with finite vertical discontinuity was studied using both modal decomposition method (MDM) and experimental method. For MDM, a global matrix formulation and orthogonality of Lamb mode was employed to describe the boundary condition of finite vertical discontinuity of the tube and the mode conversion phenomenon respectively. The final form of governing equation by MDM was a linear matrix equation which could be solved using a simple matrix identity. The calculation result showed that, below the cut-off frequency, reflection amplitudes of both A0 and S0 Lamb mode increase as the depth of discontinuity increased beyond the threshold value. An experimental investigation was performed using a Hertzian-contact transducer and steam-generator tubes to verify the calculation results by MDM. A0 Lamb mode was selected as a test signal considering the characteristics of the transducer and previous studies. The experiment for mode identification using half-sectioned tube verified that the Hertzian-contact transducer effectively generated A0 Lamb mode. Tests performed using steam-generator tubes with EDM (electric discharge machined) axial notches showed that the deeper notches produced the higher reflection echo. A0 Lamb mode interacted with the notch having a depth larger than 1/40 of wave length, or corresponding to 30% of the wall thickness. This finding was in good agreement with previous studies and the prediction by MDM. The experiment using real crack specimens to estimate the deviation of reflection amplitude showed that the reflection cross-section of real crack was very similar with that of EDM notch. Therefore, specimens with EDM notches can be used as reference blocks for Lamb wave UT calibration.

  12. Experience of steam generator tube examination in the hot laboratory of EDF: analysis of recent events concerning the secondary side

    Energy Technology Data Exchange (ETDEWEB)

    Thebault, Y.; Bouvier, O. de; Boccanfuso, M.; Coquio, N.; Barbe, V.; Molinie, E. [EDF-DIN-CEIDRE (France)

    2011-07-01

    Until 2010, more than 60 steam generator (SG) tubes have been removed and analysed in the EDF hot laboratory of CEIDRE/Chinon. This article is particularly related to three recent events that lead to the extraction of several tubes dedicated to laboratory destructive examinations. The first event that constitutes a first occurrence on the EDF Park, concerns the detection of a circumferential crack on the external surface of a tube located at tube support plate elevation. After this observation, several tubes have been extracted from Bugey 3 and Fessenheim 2 nuclear power plants with steam generators equipped with 600 MA bundle. The other two events concern the consequences of chemical cleaning of the tube bundle steam generators. The examples chosen are from Cruas 4 et Chinon B2 units whose tubes were extracted following non destructive testing performed immediately after or at the completion of cycle following the chemical cleaning. In the case of Cruas 4, Eddy Current Testing (ET) were performed for requalification of steam Generators after chemical cleaning. They allowed the detection of an indication located at the bottom of tube for a large number of tubes; the ET signal was similar to that corresponding to 'deposit' corrosion. Moreover, inspections of Chinon-B2 SGs at the end of the operation cycle following the chemical cleaning, showed the presence of conductor deposits at the bottom of some tubes. The first part of this document presents the major results of laboratory examinations of the pulled tubes of Bugey 3 and Fessenheim 2 and their analysis. Hypothesis concerning damage mechanisms of the tubes are also proposed. The second part of the paper relates the results of the laboratory examinations of the pulled tubes of Cruas 4 and Chinon B 2 after chemical cleaning and their analysis. (authors)

  13. Wear behavior of 2-1/4 Cr-1 Mo tubing against alloy 718 tube-support material in sodium-cooled steam generators

    Energy Technology Data Exchange (ETDEWEB)

    Wilson, W L

    1983-05-01

    A series of prototypic steam generator 2-{1/4} Cr-1 Mo tube/alloy 718 tube support plate wear tests were conducted in direct support of the Westinghouse Nuclear Components Division -- Breeder Reactor Components Project Large Scale steam Generator design. The initial objective was to verify the acceptable wear behavior of softer, over-aged'' alloy 718 support plate material. For all interfaces under all test conditions, resultant wear damage was adhesive in nature with varying amounts of 2-{1/4} Cr-1 Mo tube material being adhesively transferred to the alloy 718 tube supports. Maximum tube wear depths exceeded the initially established design allowable limit of 127 {mu}m (.005 in.) at 17 of the 18 interfaces tested. A decrease in contact stresses produced acceptable tube wear depths below a readjusted maximum design allowable value of 381 {mu}m (.015 in.). Additional conservatisms associated with the simulation of a 40-year lifetime of rubbing in a one-week laboratory test provided further confidence that the 381 {mu}m maximum tube wear allowance would not be exceeded in service. Softer, over-aged'' alloy 718 material was found to produce slightly less wear damage on 2-{1/4} Cr-1 Mo tubing than fully age hardened material. Also, air formed oxide films on the alloy 718 reduced initial tube wear and delayed the onset of adhesive surface damage. However, at high surface stress levels, these films were not sufficiently stable to provide adequate long term protection from adhesive wear. The results of the present work and those of previous test programs suggest that the successful in-sodium tribological performance of 2-{1/4} Cr-1 Mo/alloy 718 rubbing couples is dependent upon the presence of lubricative surface films, such as oxides and/or surface reaction or deposition products. 11 refs., 13 figs., 4 tabs.

  14. Correlation between molten vanadium salts and the structural degradation of HK-type steel superheater tubes

    Science.gov (United States)

    de Carvalho Nunes, Frederico; de Almeida, Luiz Henrique; Ribeiro, André Freitas

    2006-12-01

    HK steels are among the most used heat-resistant cast stainless steels, being corrosion-resistant and showing good mechanical properties at high service temperatures. These steels are widely used in reformer furnaces and as superheater tubes. During service, combustion gases leaving the burners come in contact with these tubes, resulting in corrosive attack and a large weight loss occurs due to the presence of vanadium, which forms low melting point salts, removing the protective oxide layer. In this work the external surface of a tube with dramatic wall thickness reduction was analyzed using light microscopy, scanning electron microscopy, and transmission electron microscopy. The identification of the phases was achieved by energy dispersive spectroscopy (EDS) analyses. The results showed oxides arising from the external surface. In this oxidized region vanadium compounds inside chromium carbide particles were also observed, due to inward vanadium diffusion during corrosion attack. A chemical reaction was proposed to explain the presence of vanadium in the metal microstructure.

  15. Design of a mobile neutron radiography installation based on a compact sealed tube neutron generator

    Institute of Scientific and Technical Information of China (English)

    MaWei-Chao; YaoAn-Ju; 等

    1997-01-01

    A series of optimum conditions are taken into account in the construction of neutron radiography(NR) installation based on a sealed tube neutron generator capable of gnerating 1010 n/s with 14MeV.The characteristics of NNU screens,a kind of self-made 6LiF.ZnS(Ag)scintillation intensifying screen are presented.Finally,some neutron radiographies taken by this NR installation and NNU screens are given.

  16. Study of Scaling Development on Tube Surfaces of Water Steam Loop in Steam Generator of CEFR

    Institute of Scientific and Technical Information of China (English)

    ZHANG; Lu; LIU; Fu-chen; LUO; De-kang; WU; Qiang; ZHANG; Huan-qi

    2012-01-01

    <正>The steam generator worked as pressure boundary of Na-H2O loop in China Experimental FastReactor (CEFR), which was quite important for nuclear reactor safety. Once the tubes separating the water from steam leak because of corrosion by scaling, Na-H2O reaction would lead to severe accident. So it’s critically important to study how the scaling develops on the water-steam sides.

  17. Impurities incorporation into magnetite scale formed on simulated steam generator tubing

    Energy Technology Data Exchange (ETDEWEB)

    Takahashi, K.; Yamaguchi, K.; Koike, M. [Kyushu Electric Power Co., Inc. (Japan); Kawamura, H.; Hirano, H. [Central Research Inst. of Electric Power Industry (Japan); Yamada, Y.; Nakamura, T. [The Kansai Electric Power Co., Inc. (Japan)

    2002-07-01

    From a viewpoint of ensuring the integrity of steam generators (SGs) tubing in PWR plants, the research was made into how impurities in the secondary coolant are incorporated into magnetite (Fe{sub 3}O{sub 4}) scale formed on the tube in a laboratory test. We experimented with a method to form Fe{sub 3}O{sub 4} scale on a tube under a boiling heat transfer condition in the laboratory test, simulating the conditions of SG in the actual PWR plants. Based on the scale formation method, we investigated the incorporation of sulfur (S) into the scale. S is known as the most common impurity solved in the secondary coolant and a dominant factor in making heat transfer crevice environment acidic. The effects of sodium (Na) and silicon (Si), solved in test solution with S, on the S incorporation into scale were also investigated. The test resulted in a double-layered scale being formed on the tube surface, with the outer scale being porous and the inner scale dense. It was revealed that the S incorporation into scales was affected by the S concentration in the solution and existence of other impurities, such as Na and Si. (authors)

  18. Heat transfer enhancement of finned oval tubes with staggered punched longitudinal vortex generators

    Energy Technology Data Exchange (ETDEWEB)

    Chen, Y.; Fiebig, M.; Mitra, N.K. [Ruhr-Universitaet Bochum (Germany). Inst. fuer Thermo- und Fluiddynamik

    2000-02-01

    Punched longitudinal vortex generators in form of winglets in staggered arrangements were employed to enhance heat transfers in high performance finned oval tube heat exchanger elements. Three-dimensional hydrodynamically and thermally developing laminar flow (Re = 300) and conjugate heat transfer in finned oval tubes were calculated by solving the Navier-Stokes and energy equations with a finite-volume method in curvilinear grids. Velocity field, pressure distribution, vortex formation, temperature fields, local heat transfer distributions and global results for finned oval tubes with two to four staggered winglets ({beta}= 30{sup o}, {lambda} = 2, h =H) were presented and compared. Winglets in staggered arrangement bring larger heat transfer enhancement than in in-line arrangement since the longitudinal vortices from the former arrangement influence a larger area and intensify the fluid motion normal to the flow direction. For Re = 300 and Fi = 500, the ratios of heat transfer enhancement to flow loss penalty (j/j{sub 0})/( f/f{sub 0}) were 1.151 and 1.097 for a finned oval tube with two and four staggered winglets, respectively. (author)

  19. A prediction method for the general corrosion behavior of Alloy 690 steam generator tube using eddy current testing

    Energy Technology Data Exchange (ETDEWEB)

    Shim, Hee-Sang; Choi, Myung Sik; Lee, Deok Hyun; Hur, Do Haeng, E-mail: dhhur@kaeri.re.kr

    2016-02-15

    Highlights: • A corrosion test for the tubes with different levels of eddy current noise was conducted. • A relationship between the corrosion rate and the eddy current noise of tubes was explored. • Corrosion rate was closely correlated to the tube noise of a rotating pancake probe. • Corrosion rate was not related to the tube noise measured using a bobbin probe. - Abstract: The purpose of this work is to develop an eddy current testing method to predict the general corrosion behavior of Alloy 690 steam generator tubes. A corrosion test was conducted for tubes with different levels of eddy current noise in simulated primary water at 330 °C, and their corrosion behavior was correlated with the tube noise measured using bobbin and rotating probes. The corrosion behavior was closely correlated with the tube noise measured using a rotating probe. However, there was no correlation between the corrosion behavior and the tube noise measured using a bobbin probe. The tube noise value measured using a rotating pancake coil probe is suggested to be a significant parameter in estimating the general corrosion behavior of tubes.

  20. An Expert System Using A Neural Network For Steam Generator Tube Inspection

    Energy Technology Data Exchange (ETDEWEB)

    Kim, Kilyoo; Huh, Younghwan [Korea Atomic Energy Research Institute, Daejeon (Korea, Republic of); Woo, Heegon; Choi, Sungsoo [Korea Electric Power Corporation, Daejeon (Korea, Republic of)

    1991-04-15

    An expert system using neural network is built to automatically evaluate eddy current (EC) signals generated during steam generator (S/G) tubes inspection. The system consists of three subsystem, i.e., syntactic pattern recognition subsystem, neural network subsystem and rule based production subsystem. The syntactic pattern recognition subsystem makes it easy to process the vast EC signal data, screens EC signals and detects event signals such as defect signals and structural signals. The neural network subsystem is useful to classify the event signals which often contain noise signals. The expert system implemented on HP 9000/370 workstation also supplies a good EC test data management function.

  1. Feasibility of leak-detection instrumentation for duplex-tube steam generator. [LMFBR

    Energy Technology Data Exchange (ETDEWEB)

    Berkey, E.; Witkowski, R.E.

    1974-01-01

    A literature search has been carried out to determine if current state-of-the-art for sodium vapor and water vapor detectors are feasible as leak detection instrumentation for the Westinghouse duplex-tube steam generator. A commercially available probe-type water vapor detector has been identified and a thermal ionization type sodium vapor detector, currently being developed by Westinghouse, has been selected as the reference sodium-vapor leak detector. Recommendations are made concerning the experimental studies required to adapt the selected instrumentation to steam-generator plant applications. Proposed future instrumentation development programs are also identified.

  2. Predictions of structural integrity of steam generator tubes under normal operating, accident, an severe accident conditions

    Energy Technology Data Exchange (ETDEWEB)

    Majumdar, S. [Argonne National Lab., IL (United States)

    1997-02-01

    Available models for predicting failure of flawed and unflawed steam generator tubes under normal operating, accident, and severe accident conditions are reviewed. Tests conducted in the past, though limited, tended to show that the earlier flow-stress model for part-through-wall axial cracks overestimated the damaging influence of deep cracks. This observation was confirmed by further tests at high temperatures, as well as by finite-element analysis. A modified correlation for deep cracks can correct this shortcoming of the model. Recent tests have shown that lateral restraint can significantly increase the failure pressure of tubes with unsymmetrical circumferential cracks. This observation was confirmed by finite-element analysis. The rate-independent flow stress models that are successful at low temperatures cannot predict the rate-sensitive failure behavior of steam generator tubes at high temperatures. Therefore, a creep rupture model for predicting failure was developed and validated by tests under various temperature and pressure loadings that can occur during postulated severe accidents.

  3. Study on the regulatory approach of KNGR multiple steam generator tube rupture events

    Energy Technology Data Exchange (ETDEWEB)

    Chang, Keun Sun; Kweon, Y. C.; Lee, S. J.; Lee, Y. S.; Cheong, D. Y.; Park, T. J.; Lee, M. G.; Cheon, Y. H. [Sunmoon Univ., Asan (Korea, Republic of); Cheong, J. H. [Baekseok College of Cultural Studies, Cheonan (Korea, Republic of)

    2001-10-15

    The scope and contents performed in this project are as follows : firstly, reviews of the structure and contents of local and foreign regulatory requirements as well as analysis of design features related to safety improvement and containment bypass during multiple steam generator tube failure of advanced reactors of domestic and foreign countries. Secondly, analyses of the state-of-the-art of the development of local and foreign regulatory requirements, research trends, design features and safety goals of advanced reactors, especially for technical issues related to the containment bypass during MSGTR event. Thirdly, analyses of the event of MSGTR for the KNGR using MAS 1.4 which is the best-estimate system code developed by Korea Atomic Energy Research Institute. Errors in input-decks established last year have been corrected during this analysis. Fourthly, assessment of the effects of several parameters on the consequences following a MSGTR event. Tube rupture location, selection of affected steam generator, tube modeling method, discharge coefficient (C{sub D}) are examined. Fifthly, establishment of regulatory direction of technical issues related to the containment bypass during MSGTR event.

  4. Messenger RNas : their utilization and degradation during pollen germination and tube growth

    Directory of Open Access Journals (Sweden)

    Joseph P. Mascarenhas

    2014-01-01

    Full Text Available During pollen germination and tube growth at least 230 new proteins are synthesized, as determined by 35S-methionime labeling and two dimensional gel electrophoretic analysis of the labeled proteins. The same number and pattern of protein spots is seen whether or not actinomycin D is included in the, medium, indicating that the mRNAs present in the unger-minated pollen grain and those newly synthesized code for the same proteins. The genetic program during at least the latter part of pollen maturation prior to anthesis and that during pollen germination and tube growth thus appears to be similar if not identical. During the first hour of pollen tube growth about 500/0 of the protein synthesis that occurs utilizes previously synthesized mRNAs. The remaining 50% occurs on newly made mRNAs. The ungerminated mature pollen grain contains 196 pg of RNA and approximately 6 X 106 molecules of poly(A+ RNA, i.e. mRNAs. The rate of protein synthesis corrected for internal pool changes in the labeled amino acid used (3H-leucine is highest during the first 15 min of pollen tube growth. The rate decreases rapidly thereafter for the next 45 min. Concurrent with the reduction in rate of protein synthesis there is a reduction in the poly(A content of the pollen RNA and in the amount of poly(A per pollen, grain. The total RNA per pollen grain, however, appears not to change during this period.

  5. Simulation of the fluid-structure-interaction of steam generator tubes and bluff bodies

    Energy Technology Data Exchange (ETDEWEB)

    Kuehlert, Karl [ANSYS, Inc. (United States)], E-mail: kue@fluent.com; Webb, Stephen [Sandia National Laboratories (United States); Schowalter, David; Holmes, William; Chilka, Amarvir; Reuss, Steve [ANSYS, Inc. (United States)

    2008-08-15

    The accuracy of computational fluid dynamics in simulating the cross-flow around a steam generator and the feasibility of a full scale coupled CFD/FEA fluid-structure-interaction (FSI) analysis is examined through successive validations. The study begins with a comparison between experiment and computation of flow within a stationary tube bank. Results from the simulation of an individual tube experiencing two-degree-of-freedom flow-induced vibration (at a Reynolds number of 3800) are then shown to compare favorably to experimental results. Finally, free vibration of a single cantilevered hydrofoil is simulated with comparison of mean square acceleration at resonant and non-resonant velocities, respectively. The magnitudes and frequencies of vibration are shown to be accurately captured.

  6. The optimum fin spacing of circular tube bank fin heat exchanger with vortex generators

    Science.gov (United States)

    Hu, Wanling; Su, Mei; Wang, Liangcheng; Zhang, Qiang; Chang, Limin; Liu, Song; Wang, Liangbi

    2013-09-01

    In real application, once the pattern of fin is determined, fin spacing of tube bank fin heat exchanger can be adjusted in a small region, and air flow velocity in the front of the heat exchanger is not all the same. Therefore, the effects of fin spacing on heat transfer performance of such heat exchanger are needed. This paper numerically studied the optimal fin spacing regarding the different front flow velocities of a circular tube bank fin heat exchanger with vortex generators. To screen the optimal fin spacing, an appropriate evaluation criterion JF was used. The results show that when front velocity is 1.75 m/s, the optimal fin spacing is 2.25 mm, when front velocity is 2.5 m/s, the optimal fin spacing is 2 mm, and when front velocity is higher than 2.5 m/s, the optimal fin spacing is 1.75 mm.

  7. Studies on flow instability of helical tube steam generator with Nyquist criterion

    Energy Technology Data Exchange (ETDEWEB)

    Niu, Fenglei, E-mail: niufenglei@ncepu.edu.cn [State Key Laboratory of Alternate Electrical Power System with Renewable Energy Sources, North China Electric Power University, Beijing 102206 (China); Tian, Li; Yu, Yu [State Key Laboratory of Alternate Electrical Power System with Renewable Energy Sources, North China Electric Power University, Beijing 102206 (China); Li, Rizhu [Institute of Nuclear and New Energy Technology, Tsinghua University, Beijing 100084 (China); Norman, Timothy L. [Westinghouse Electric Company, Madison, PA 15663 (United States)

    2014-01-15

    Highlights: • Density-wave oscillation in helical-tube steam generators was studied. • The multi-variable frequency domain method was used for the modeling. • The flow stability was evaluated by the Nyquist stability criterion. • The calculated results are consistent with the experimental results. -- Abstract: The steam generator of the 10 MW High Temperature Gas-Cooled Reactor (HTR-10) in China consists of a series of helical tubes where water/steam flows inside and helium flows outside. It operates under middle pressure, which tends to cause the flow instability. Density-wave oscillation is the most common type of two-phase flow instability in the steam generators. This paper presents the research on flow instability for the HTR-10 steam generator. The drift flux model was used for two-phase flow analysis. The transfer matrix was obtained by using linearized perturbation and Laplace transformation on the conservation equations. The flow stability was evaluated by the Nyquist stability criterion. The results obtained from frequency domain method were compared and discussed with the results from the time domain method and the experimental results.

  8. CFD evaluation on the thermohydraulic characteristics of tube support plates in steam generator

    Energy Technology Data Exchange (ETDEWEB)

    Zhang, B.; Zhang, H.; Han, B.; Yang, B.W. [Xi' an Jiaotong Univ. (China). School of Nuclear Science and Technology; Mo, S.J.; Ren, H.B.; Qin, J.M.; Zuo, C.P. [China Nuclear Power Design Co. Ltd., ShenZhen (China)

    2016-07-15

    The integrity and thermal hydraulic characteristics of steam generator are of great concern in the nuclear industry. The tube support plates (TSP), one of the most important components of the steam generator, not only support the heat transfer tubes, but also affect the flow dynamic and thermal hydraulic characteristics of the secondary-side flow inside the steam generator. Different working conditions, ranging from single-phase adiabatic condition to two-phase high-void boiling condition, are simulated and analyzed. Calculated void fraction, under simple geometry, agrees well with the experiment data whilst the simulated heat transfer coefficient is tremendously close to the empirical correlation. Temperature, void fraction, and velocity distributions in different locations show reasonable distribution. The simulation results indicate that TSP can enhance the heat transfer in the secondary side of the steam generator. On the top of TSP, with the increase in cross-section flow area, the back-flow phenomenon occurs, which might lead to the contamination of precipitation.

  9. 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.

  10. Detecting volatile compounds from Kraft lignin degradation in the headspace of microbial cultures by selected ion flow tube mass spectrometry (SIFT-MS).

    Science.gov (United States)

    Gibson, Andrew; Malek, Lada; Dekker, Robert F H; Ross, Brian

    2015-05-01

    Selected Ion Flow Tube Mass Spectrometry (SIFT-MS) was used to quantify methanol and other volatile compounds in the headspace of one bacterial and 12 fungal lignin-degrading microbial cultures. Cultures were grown in 250 mL Erlenmeyer flasks capped with aluminum foil containing 40 mL of nutrient media using Kraft lignin (0.3% w/v) as the sole carbon source. Analysis was done using SIFT-MS with H3O(+) and NO(+) precursors. Product ions were identified with multiple ion mode (MIM). Full scan (FS) mode was used to identify other compounds of interest. Absidia cylindrospora, Ischnoderma resinosum and Pholiota aurivella increased headspace methanol concentration by 136 ppb, 1196 ppb and 278 ppb, respectively, while Flammulina velutipes and Laetiporus sulphureus decreased concentration below ambient levels. F. velutipes and L. sulphureus were found to produce products of methanol oxidation (formaldehyde and formic acid) and were likely metabolizing methanol. Some additional unidentified compounds generated by the fungal cultures are intriguing and will require further study. SIFT-MS can be used to quantify methanol and other volatile compounds in the headspace of microbial cultures and has the potential to be a rapid, sensitive, non-invasive tool useful in elucidating the mechanisms of lignin degradative pathways.

  11. THE EFFECTS OF SWIRL GENERATOR HAVING WINGS WITH HOLES ON HEAT TRANSFER AND PRESSURE DROP IN TUBE HEAT EXCHANGER

    Directory of Open Access Journals (Sweden)

    Zeki ARGUNHAN

    2006-02-01

    Full Text Available This paper examines the effect of turbulance creators on heat transfer and pressure drop used in concentric heat exchanger experimentaly. Heat exchanger has an inlet tube with 60 mm in diameter. The angle of swirl generators wings is 55º with each wing which has single, double, three and four holes. Swirl generators is designed to easily set to heat exchanger entrance. Air is passing through inner tube of heat exhanger as hot fluid and water is passing outer of inner tube as cool fluid.

  12. The development of an inspection/maintence robot for steam generator tubes

    Energy Technology Data Exchange (ETDEWEB)

    Kim, Seung Ho; Kim, Chang Hoi; Seo, Yong Chil [and others

    2003-05-01

    We developed the tele-robotic systems for inspection/maintenance of steam generator tubes. For easy handling and installation, it consists of three separable parts: the entering/leaving device, the base posture adjusting device, the manipulator. The inspection and repair tools, such as brushing, plugging, and sleeving tools, were developed. We also developed software programs for the eddy current test signal acquisition and evaluation. The semiconductor type dosimeter and the directional radiation mapping module were developed for measuring the accumulated radioactivity and for finding the radioactivity source location. The research for radiation shield and decontamination were carried out. The developed robotic system has been tested in the Ulchin NPP type steam generator mockup in our laboratory, and after evaluation and some modification the final functional test was carried out at the Kori NPP type steam generator mockup in the Kori training center.

  13. Development of a 3D Electromagnetic Model for Eddy Current Tubing Inspection: Application to Steam Generator Tubing

    Science.gov (United States)

    Pichenot, G.; Prémel, D.; Sollier, T.; Maillot, V.

    2004-02-01

    In nuclear plants, the inspection of heat exchanger tubes is usually carried out by using eddy current nondestructive testing. A numerical model, based on a volume integral approach using the Green's dyadic formalism, has been developed, with support from the French Institute for Radiological Protection and Nuclear Safety, to predict the response of an eddy current bobbin coil to 3D flaws located in the tube's wall. With an aim of integrating this model into the NDE multi techniques platform CIVA, it has been validated with experimental data for 2D and 3D flaws.

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

    Energy Technology Data Exchange (ETDEWEB)

    Sidhu, B.S.; Prakash, S.

    2006-03-15

    Boiler tube steels, namely low carbon steel ASTM-SA210-Grade A1 (GrA1), 1Cr-0.5Mo steel ASTM-SA213-T-11 (T11), and 2.25Cr-1Mo steel ASTM-SA213-T-22 (T22), were used as substrate steels. Ni-22Cr-10AI-1Y powder was sprayed as a bond coat 150 {mu}m thick before a 200 {mu}m final coating of Ni-20Cr was applied. Coatings were characterized prior to testing in the environment of a coal fired boiler. The uncoated and coated steels were inserted in the platen superheater zone of a coal fired boiler at around 755{sup o}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. 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.

  16. Heat transfer enhancement by a multilobe vortex generator in internally finned tubes

    Energy Technology Data Exchange (ETDEWEB)

    Tsui, Y.Y.; Leu, S.W. [National Chiao Tung Univ., Hsinchu (Taiwan, Province of China). Dept. of Mechanical Engineering

    1999-04-01

    A three-dimensional computational method is employed to study the flow and heat transfer in internally finned tubes with a multilobe vortex generator inserted. Governing equations are discretized using the finite volume method. The irregular lobe geometry is treated using curvilinear nonstaggered grids. The linear interpolation method is adopted to calculate face velocities. The results show that secondary flows induced by the lobes are transformed to become axial vortices downstream of the vortex generator. As a consequence of the transport by the vortex flow, the core flow is moved to the fins and the tube wall, while the wall flow moves to the core. In this way, both heat transfer and flow mixing are enhanced. When the fin height is increased, the axial vortex is more restricted in the centerline region, and the strength of the vortex flow, represented by circulation, is decreased. In turn, the total pressure loss is also decreased. However, the heat transfer increases with fin height. Consequently, efficiency is greatly promoted.

  17. Impulse Generation Mechanisms in a Laser-Driven In-Tube Accelerator

    Science.gov (United States)

    Choi, Jeong-Yeol; Kang, Ki-Ha; Sasoh, Akihiro; Jeung, In-Seuck; Urabe, Naohide; Kleine, Harald

    To enhance laser-propulsion thrust performance, a unique Laser-driven In-Tube Accelerator (LITA) has been developed. This paper numerically analyzes the impulse generation mechanisms in LITA. For this purpose, a LITA performance experiment was conducted in atmospheric air with a projectile installed on a ballistic pendulum to calibrate the numerical approximations. We conducted experimental flow visualization by framing shadowgraph and computational fluid dynamics solving the axi-symmetric Euler equation applied to an ideal gas. The results show that a laser-driven blast wave is generated by a spherical hot gas core where the supplied laser energy is absorbed first. The effect of confinement by the tube or shroud wall is confirmed. The impulse production is established not only from the interaction between the incident blast wave and projectile, but also from the following repetitive pressure waves. Assuming that about 30% of the input laser energy is absorbed by the working air, both the impulse and peak pressure agrees quantitatively between the experiment and numerical simulation.

  18. The optimization of fin-tube heat exchanger with longitudinal vortex generators using response surface approximation and genetic algorithm

    Science.gov (United States)

    Wu, Xuehong; Liu, DanDan; Zhao, Min; Lu, YanLi; Song, Xiaoyong

    2016-09-01

    Delta winglet works better than other vortex generators in improving the performance of fin-tube heat exchangers. In this paper, Response Surface Approximation is used to study the effects of the fin pitch, the ratio of the longitudinal tube pitch to transverse tube pitch, the ratio of both sides V 1 , V h of delta winglets and the attack angle of delta winglets on the performance of fin-tube heat exchanger. Firstly, Twenty-nine numerical group experiments including five times repeated experiments at the central point are conducted. Then, the analyses of variable (ANOVA) and regression are performed to verify the accuracy of the polynomial coefficients. Finally, the optimization of the fin-tube heat exchanger using the Genetic Algorithm is conducted and the best performance of j/f (1/3) is found to be 0.07945, which is consistent with the numerical result.

  19. Microplastic Generation in the Marine Environment Through Degradation and Fragmentation

    Science.gov (United States)

    Perryman, M. E.; Jambeck, J.; Woodson, C. B.; Locklin, J.

    2016-02-01

    Plastic use has become requisite in our global economy; as population continues to increase, so too, will plastic production. At its end-of-life, some amount of plastic is mismanaged and ends up in the ocean. Once there, various environmental stresses eventually fragment plastic into microplastic pieces, now ubiquitous in the marine environment. Microplastics pose a serious threat to marine biota and possibly humans. Though the general mechanisms of microplastic formation are known, the rate and extent is not. Currently, no standard methodology for testing the formation of microplastic exists. We developed a replicable and flexible methodology for testing the formation of microplastics. We used this methodology to test the effects of UV, thermal, and mechanical stress on various types of plastic. We tested for fragmentation by measuring weight and size distribution, and looked for signs of degraded plastic using Fourier transform infrared spectroscopy. Though our results did not find any signs of fragmentation, we did see degradation. Additionally, we established a sound methodology and provided a benchmark for additional studies.

  20. Development of a novel miniature detonation-driven shock tube assembly that uses in situ generated oxyhydrogen mixture

    Science.gov (United States)

    Janardhanraj, S.; Jagadeesh, G.

    2016-08-01

    A novel concept to generate miniature shockwaves in a safe, repeatable, and controllable manner in laboratory confinements using an in situ oxyhydrogen generator has been proposed and demonstrated. This method proves to be more advantageous than existing methods because there is flexibility to vary strength of the shockwave, there is no need for storage of high pressure gases, and there is minimal waste disposal. The required amount of oxyhydrogen mixture is generated using alkaline electrolysis that produces hydrogen and oxygen gases in stoichiometric quantity. The rate of oxyhydrogen mixture production for the newly designed oxyhydrogen generator is found to be around 8 ml/s experimentally. The oxyhydrogen generator is connected to the driver section of a specially designed 10 mm square miniature shock tube assembly. A numerical code that uses CANTERA software package is used to predict the properties of the driver gas in the miniature shock tube. This prediction along with the 1-D shock tube theory is used to calculate the properties of the generated shockwave and matches reasonably well with the experimentally obtained values for oxyhydrogen mixture fill pressures less than 2.5 bars. The miniature shock tube employs a modified tri-clover clamp assembly to facilitate quick changing of diaphragm and replaces the more cumbersome nut and bolt system of fastening components. The versatile nature of oxyhydrogen detonation-driven miniature shock tube opens up new horizons for shockwave-assisted interdisciplinary applications.

  1. Study of Microstructure Degradation of Boiler Tubes Due To Creep for Remaining Life Analysis

    Directory of Open Access Journals (Sweden)

    Kavita Sankhala

    2014-07-01

    Full Text Available In the current scenario of power shortage in India, the main objective is to ensure availability of power plant and increasing its reliability. During assessment ,testing and inspection a simple question has to be asked again and again‖ How long the particular power plants can be operated safely and cost-effectively with satisfying increased requirements and operational availability with reduced pollutant emissions, even after their designed life. So to answer this important question regarding the operational capability of the existing plant the remaining life analysis (RLA has to be done. The condition of the plant equipments can be assessed only by way of a RLA methodology. On the basis of RLA proper decision can be made about the plants safety and availability. There are many methods to carry out the RLA of the critical components out of which ―microstructure study‖ is a method. In this paper we have tried to outline the RLA procedures and review the various damage mechanisms based on microstructure study. It is also presents the microstructure changes and properties of 106720 service hour exposed boiler tube in a 120 MW boiler of a thermal power plant.

  2. Estimation of a tube diameter in a ‘church window’ condenser based on entropy generation minimization

    Directory of Open Access Journals (Sweden)

    Laskowski Rafał

    2015-09-01

    Full Text Available The internal diameter of a tube in a ‘church window’ condenser was estimated using an entropy generation minimization approach. The adopted model took into account the entropy generation due to heat transfer and flow resistance from the cooling-water side. Calculations were performed considering two equations for the flow resistance coefficient for four different roughness values of a condenser tube. Following the analysis, the internal diameter of the tube was obtained in the range of 17.5 mm to 20 mm (the current internal diameter of the condenser tube is 22 mm. The calculated diameter depends on and is positively related to the roughness assumed in the model.

  3. Electron beam generation and structure of defects in carbon and boron nitride nano-tubes

    Energy Technology Data Exchange (ETDEWEB)

    Zobelli, A

    2007-10-15

    The nature and role of defects is of primary importance to understand the physical properties of C and BN (boron nitride) single walled nano-tubes (SWNTs). Transmission electron microscopy (TEM) is a well known powerful tool to study the structure of defects in materials. However, in the case of SWNTs, the electron irradiation of the TEM may knock out atoms. This effect may alter the native structure of the tube, and has also been proposed as a potential tool for nano-engineering of nano-tubular structures. Here we develop a theoretical description of the irradiation mechanism. First, the anisotropy of the emission energy threshold is obtained via density functional based calculations. Then, we numerically derive the total Mott cross section for different emission sites of carbon and boron nitride nano-tubes with different chiralities. Using a dedicated STEM (Scanning Transmission Electron Microscope) microscope with experimental conditions optimised on the basis of derived cross-sections, we are able to control the generation of defects in nano-tubular systems. Either point or line defects can be obtained with a spatial resolution of a few nanometers. The structure, energetics and electronics of point and line defects in BN systems have been investigated. Stability of mono- and di- vacancy defects in hexagonal boron nitride layers is investigated, and their activation energies and reaction paths for diffusion have been derived using the nudged elastic band method (NEB) combined with density functional based techniques. We demonstrate that the appearance of extended linear defects under electron irradiation is more favorable than a random distribution of point defects and this is due to the existence of preferential sites for atom emission in the presence of pre-existing defects, rather than thermal vacancy nucleation and migration. (author)

  4. Next Generation TRD for CREAM Using Gas Straw Tubes and Foam Radiators

    Science.gov (United States)

    Malinin, A.; Ahn, H.S.; Fedin, O.; Ganel, O.; Han, J.H.; Kim, C.H.; Kim, K.C.; Lee, M.H.; Lutz, L.; Seo, E.S.; Walpole, P.; Wu, J.; Yoo, J.H.; Yoon, Y.S.; Zinn, S.Y.

    The Cosmic Ray Energetics And Mass (CREAM) experiment is designed to investigate the source, propagation and acceleration mechanism of high energy cosmic-ray nuclei, by directly measuring their energy and charge. Incorporating a transition radiation detector (TRD) provides an energy measurement complementary to the calorimeter, as well as additional track reconstruction capability. The next generation CREAM TRD is designed with 4 mm straw tubes to greatly improve tracking over the previous 20 mm tube design, thereby enhancing charge identification in the silicon charge detector (SCD). Plastic foam provides a weight-efficient radiator that doubles as a mechanical support for the straw layers. This design provides a compact, robust, reliable, low density detector to measure incident nucleus energy for 3 < Z < 30 nuclei in the Lorentz gamma factor range of 102-105. This paper discusses the new TRD design and the low power front end electronics used to achieve the large dynamic range required. Beam test results of a prototype TRD are also reported.

  5. YouTube as a crowd-generated water level archive.

    Science.gov (United States)

    Michelsen, N; Dirks, H; Schulz, S; Kempe, S; Al-Saud, M; Schüth, C

    2016-10-15

    In view of the substantial costs associated with classic monitoring networks, participatory data collection methods can be deemed a promising option to obtain complementary data. An emerging trend in this field is social media mining, i.e., harvesting of pre-existing, crowd-generated data from social media. Although this approach is participatory in a broader sense, the users are mostly not aware of their participation in research. Inspired by this novel development, we demonstrate in this study that it is possible to derive a water level time series from the analysis of multiple YouTube videos. As an example, we studied the recent water level rise in Dahl Hith, a Saudi Arabian cave. To do so, we screened 16 YouTube videos of the cave for suitable reference points (e.g., cave graffiti). Then, we visually estimated the distances between these points and the water level and traced their changes over time. To bridge YouTube hiatuses, we considered own photos taken during two site visits. For the time period 2013-2014, we estimate a rise of 9.5m. The fact that this rise occurred at a somewhat constant rate of roughly 0.4m per month points towards a new and permanent water source, possibly two nearby lakes formed from treated sewage effluent. An anomaly in the rising rate is noted for autumn 2013 (1.3m per month). As this increased pace coincides with a cluster of rain events, we deem rapid groundwater recharge along preferential flow paths a likely cause. Despite the sacrifice in precision, we believe that YouTube harvesting may represent a viable option to gather historical water levels in data-scarce settings and that it could be adapted to other environments (e.g., flood extents). In certain areas, it might provide an additional tool for the monitoring toolbox, thereby possibly delivering hydrological data for water resources management. Copyright © 2016 Elsevier B.V. All rights reserved.

  6. Test-tube simulated lipofuscinogenesis. Effect of oxidative stress on autophagocytotic degradation.

    Science.gov (United States)

    Yin, D; Yuan, X; Brunk, U T

    1995-06-30

    Cysteine-stimulated oxidation of a rat liver lysosomal-mitochondrial fraction (LMF) was studied. The process would simulate oxidative stress-related events during the degradation of autophagocytosed material within secondary lysosomes, which may contribute to the formation of lipofuscin or age pigment. Millimolar concentration of cysteine was needed to stimulate LMF lipid peroxidation, measured as thiobarbituric acid reactive substances (TBARS). The amount of endogenous LMF iron was 545 micrograms/l and was enough to initiate peroxidation, probably through the reduction of ferric to ferrous iron by cysteine with induction of Fenton chemistry. Peroxidation could be completely inhibited by the addition of the iron chelator desferal or the antioxidant BHT. A substantial amount of the formed TBARS was associated with trichloroacetic acid (TCA) precipitable proteins. Elevated protein carbonyls was observed 1-2 h after the increase of TBARS. The tryptophan-tyrosine related protein autofluorescence (280/335 nm) decreased sharply during the first few hours of incubation. In contrast, a lipofuscin-type autofluorescence (345/430 nm) appeared only after a few days, suggesting that the latter fluorophore is not an immediate product of protein oxidation. The sequential formation of TBARS, protein carbonyls and lipofuscin-type autofluorescence as well as their dependence on iron and reducing agent add further support to the concept that lipofuscin forms in secondary lysosomes as a result of iron-catalyzed oxidative reactions involving autophagocytosed materials.

  7. Probability of detection model for the non-destructive inspection of steam generator tubes of PWRs

    Science.gov (United States)

    Yusa, N.

    2017-06-01

    This study proposes a probability of detection (POD) model to discuss the capability of non-destructive testing methods for the detection of stress corrosion cracks appearing in the steam generator tubes of pressurized water reactors. Three-dimensional finite element simulations were conducted to evaluate eddy current signals due to stress corrosion cracks. The simulations consider an absolute type pancake probe and model a stress corrosion crack as a region with a certain electrical conductivity inside to account for eddy currents flowing across a flaw. The probabilistic nature of a non-destructive test is simulated by varying the electrical conductivity of the modelled stress corrosion cracking. A two-dimensional POD model, which provides the POD as a function of the depth and length of a flaw, is presented together with a conventional POD model characterizing a flaw using a single parameter. The effect of the number of the samples on the PODs is also discussed.

  8. Improvements in the simulation of a main steam line break with steam generator tube rupture

    Science.gov (United States)

    Gallardo, Sergio; Querol, Andrea; Verdú, Gumersindo

    2014-06-01

    The result of simultaneous Main Steam Line Break (MSLB) and a Steam Generator Tube Rupture (SGTR) in a Pressurized Water Reactor (PWR) is a depressurization in the secondary and primary system because both systems are connected through the SGTR. The OECD/NEA ROSA-2 Test 5 performed in the Large Scale Test Facility (LSTF) reproduces these simultaneous breaks in a Pressurized Water Reactor (PWR). A simulation of this Test 5 was made with the thermal-hydraulic code TRACE5. Some discrepancies found, such as an underestimation of SG-A secondary pressure during the depressurization and overestimation of the primary pressure drop after the first Power Operated Relief Valve (PORV) opening can be improved increasing the nodalization of the Upper Head in the pressure vessel and meeting the actual fluid conditions of Upper Head during the transient.

  9. Impulsively Generated Sausage Waves in Coronal Tubes with Transversally Continuous Structuring

    Science.gov (United States)

    Yu, Hui; Li, Bo; Chen, Shao-Xia; Xiong, Ming; Guo, Ming-Zhe

    2016-12-01

    The frequency dependence of the longitudinal group speeds of trapped sausage waves plays an important role in determining impulsively generated wave trains, which have often been invoked to account for quasi-periodic signals in coronal loops. We examine how the group speeds ({v}{gr}) depend on angular frequency (ω) for sausage modes in pressureless coronal tubes with continuous transverse density distributions by solving the dispersion relation pertinent to the case where the density inhomogeneity of arbitrary form occurs in a transition layer of arbitrary thickness. We find that in addition to the transverse lengthscale l and density contrast {ρ }{{i}}/{ρ }{{e}}, the group speed behavior also depends on the detailed form of the density inhomogeneity. For parabolic profiles, {v}{gr} always decreases with ω first before increasing again, as happens for the much studied top-hat profiles. For linear profiles, however, the behavior of the ω -{v}{gr} curves is more complex. When {ρ }{{i}}/{ρ }{{e}}≲ 6, the curves become monotonical for large values of l. On the other hand, for higher density contrasts, a local maximum {v}{gr}\\max exists in addition to a local minimum {v}{gr}\\min when coronal tubes are diffuse. With time-dependent computations, we show that the different behavior of group speed curves, the characteristic speeds {v}{gr}\\min and {v}{gr}\\max in particular, is reflected in the temporal evolution and Morlet spectra of impulsively generated wave trains. We conclude that the observed quasi-periodic wave trains not only can be employed to probe such key parameters as density contrasts and profile steepness, but also have the potential to discriminate between the unknown forms of the transverse density distribution.

  10. Heat transfer and flow characteristics of fin-tube bundles with and without winglet-type vortex generators

    Energy Technology Data Exchange (ETDEWEB)

    Kwak, K.M.; Torii, K.; Nishino, K. [Department of Mechanical Engineering, Yokohama National University, 79-5 Tokiwadai, Hodogaya-ku, Yokohama, 240-8501 (Japan)

    2002-11-01

    The objective of this research is to investigate the effect of longitudinal vortices that can be applied to the heat transfer enhancement for fin-tube heat exchangers such as air-cooled condensers. A multichannel test core was designed and fabricated for the determination of overall heat transfer and pressure loss with circular tubes and winglet vortex generators. Heat transfer results were obtained using a transient method referred to as the modified single-blow method. For a three-row tube bundle in an in-line arrangement without winglets, the heat transfer and the pressure loss were 72% and 210% higher, respectively, than for a multichannel test core without any built-in tube or winglet. These increases were caused by vortices around the tube banks. The corresponding increases for a staggered tube bundle are 95% and 310%, respectively. The triangular winglets recommended by the previous studies in a fin-tube bundle in an in-line arrangement increase the overall heat transfer 10-25% and the pressure loss 20-35% for the Reynolds numbers ranging from 300 to 2700. (orig.)

  11. YouTube Fridays: Engaging the Net Generation in 5 Minutes a Week

    Science.gov (United States)

    Liberatore, Matthew W.

    2010-01-01

    YouTube Fridays is a teaching tool that devotes the first five minutes of class each Friday to a YouTube video related to the course. Students select the videos, which expand the class's educational content in courses such as thermodynamics and material and energy balances. From assessments of two pilot studies using YouTube Fridays in Chemical…

  12. Spanish approach to research and development applied to steam generator tubes structural integrity and life management

    Energy Technology Data Exchange (ETDEWEB)

    Lozano, J. [Associacion Nuclear Asco AIE, Barcelona (Spain); Bollini, G.J.

    1997-02-01

    The operating experience acquired from certain Spanish Nuclear Power Plant steam generators shows that the tubes, which constitute the second barrier to release of fission products, are susceptible to mechanical damage and corrosion as a result of a variety of mechanisms, among them wastage, pitting, intergranular attack (IGA), stress-corrosion cracking (SCC), fatigue-induced cracking, fretting, erosion/corrosion, support plate denting, etc. These problems, which are common in many plants throughout the world, have required numerous investments by the plants (water treatment plants, replacement of secondary side materials such as condensers and heaters, etc.), have meant costs (operation, inspection and maintenance) and have led to the unavailability of the affected units. In identifying and implementing all these preventive and corrective measures, the Spanish utilities have moved through three successive stages: in the initial stage, the main source of information and of proposals for solutions was the Plant Vendor, whose participation in this respect was based on his own Research and Development programs; subsequently, the Spanish utilities participated jointly in the EPRI Steam Generator Owners Group, collaborating in financing; finally, the Spanish utilities set up their own Steam Generator Research and Development program, while maintaining relations with EPRI programs and those of other countries through information interchange.

  13. Hemoglobin fructation promotes heme degradation through the generation of endogenous reactive oxygen species.

    Science.gov (United States)

    Goodarzi, M; Moosavi-Movahedi, A A; Habibi-Rezaei, M; Shourian, M; Ghourchian, H; Ahmad, F; Farhadi, M; Saboury, A A; Sheibani, N

    2014-09-15

    Protein glycation is a cascade of nonenzymatic reactions between reducing sugars and amino groups of proteins. It is referred to as fructation when the reducing monosaccharide is fructose. Some potential mechanisms have been suggested for the generation of reactive oxygen species (ROS) by protein glycation reactions in the presence of glucose. In this state, glucose autoxidation, ketoamine, and oxidative advance glycation end products (AGEs) formation are considered as major sources of ROS and perhaps heme degradation during hemoglobin glycation. However, whether fructose mediated glycation produces ROS and heme degradation is unknown. Here we report that ROS (H2O2) production occurred during hemoglobin fructation in vitro using chemiluminescence methods. The enhanced heme exposure and degradation were determined using UV-Vis and fluorescence spectrophotometry. Following accumulation of ROS, heme degradation products were accumulated reaching a plateau along with the detected ROS. Thus, fructose may make a significant contribution to the production of ROS, glycation of proteins, and heme degradation during diabetes.

  14. Hemoglobin fructation promotes heme degradation through the generation of endogenous reactive oxygen species

    Science.gov (United States)

    Goodarzi, M.; Moosavi-Movahedi, A. A.; Habibi-Rezaei, M.; Shourian, M.; Ghourchian, H.; Ahmad, F.; Farhadi, M.; Saboury, A. A.; Sheibani, N.

    2014-09-01

    Protein glycation is a cascade of nonenzymatic reactions between reducing sugars and amino groups of proteins. It is referred to as fructation when the reducing monosaccharide is fructose. Some potential mechanisms have been suggested for the generation of reactive oxygen species (ROS) by protein glycation reactions in the presence of glucose. In this state, glucose autoxidation, ketoamine, and oxidative advance glycation end products (AGEs) formation are considered as major sources of ROS and perhaps heme degradation during hemoglobin glycation. However, whether fructose mediated glycation produces ROS and heme degradation is unknown. Here we report that ROS (H2O2) production occurred during hemoglobin fructation in vitro using chemiluminescence methods. The enhanced heme exposure and degradation were determined using UV-Vis and fluorescence spectrophotometry. Following accumulation of ROS, heme degradation products were accumulated reaching a plateau along with the detected ROS. Thus, fructose may make a significant contribution to the production of ROS, glycation of proteins, and heme degradation during diabetes.

  15. STEAM GENERATOR GROUP PROJECT

    Energy Technology Data Exchange (ETDEWEB)

    Clark, R. A.; Lewis, M

    1985-09-01

    This report is a summary of progress in the Surry Steam Generator Group Project for 1984. Information is presented on the analysis of two baseline eddy current inspections of the generator. Round robin series of tests using standard in-service inspection techniques are described along with some preliminary results. Observations are reported of degradation found on tubing specimens removed from the generator, and on support plates characterized in-situ. Residual stresses measured on a tubing specimen are reported. Two steam generator repair demonstrations are described; one for antivibration bar replacement, and one on tube repair methods. Chemical analyses are shown for sludge samples removed from above the tube sheet.

  16. GENERATION OF MAGNETOHYDRODYNAMIC WAVES IN LOW SOLAR ATMOSPHERIC FLUX TUBES BY PHOTOSPHERIC MOTIONS

    Energy Technology Data Exchange (ETDEWEB)

    Mumford, S. J.; Fedun, V.; Erdélyi, R., E-mail: s.mumford@sheffield.ac.uk [Solar Physics and Space Plasma Research Centre (SP2RC), School of Mathematics and Statistics, The University of Sheffield, Hicks Building, Hounsfield Road, Sheffield S3 7RH UK (United Kingdom)

    2015-01-20

    Recent ground- and space-based observations reveal the presence of small-scale motions between convection cells in the solar photosphere. In these regions, small-scale magnetic flux tubes are generated via the interaction of granulation motion and the background magnetic field. This paper studies the effects of these motions on magnetohydrodynamic (MHD) wave excitation from broadband photospheric drivers. Numerical experiments of linear MHD wave propagation in a magnetic flux tube embedded in a realistic gravitationally stratified solar atmosphere between the photosphere and the low choromosphere (above β = 1) are performed. Horizontal and vertical velocity field drivers mimic granular buffeting and solar global oscillations. A uniform torsional driver as well as Archimedean and logarithmic spiral drivers mimic observed torsional motions in the solar photosphere. The results are analyzed using a novel method for extracting the parallel, perpendicular, and azimuthal components of the perturbations, which caters to both the linear and non-linear cases. Employing this method yields the identification of the wave modes excited in the numerical simulations and enables a comparison of excited modes via velocity perturbations and wave energy flux. The wave energy flux distribution is calculated to enable the quantification of the relative strengths of excited modes. The torsional drivers primarily excite Alfvén modes (≈60% of the total flux) with small contributions from the slow kink mode, and, for the logarithmic spiral driver, small amounts of slow sausage mode. The horizontal and vertical drivers primarily excite slow kink or fast sausage modes, respectively, with small variations dependent upon flux surface radius.

  17. Development of a Robust Model-Based Water Level Controller for U-Tube Steam Generator

    Energy Technology Data Exchange (ETDEWEB)

    Basher, A.M.H.

    2001-09-04

    Poor control of steam generator water level of a nuclear power plant may lead to frequent nuclear reactor shutdowns. These shutdowns are more common at low power where the plant exhibits strong non-minimum phase characteristics and flow measurements at low power are unreliable in many instances. There is need to investigate this problem and systematically design a controller for water level regulation. This work is concerned with the study and the design of a suitable controller for a U-Tube Steam Generator (UTSG) of a Pressurized Water Reactor (PWR) which has time varying dynamics. The controller should be suitable for the water level control of UTSG without manual operation from start-up to full load transient condition. Some preliminary simulation results are presented that demonstrate the effectiveness of the proposed controller. The development of the complete control algorithm includes components such as robust output tracking, and adaptively estimating both the system parameters and state variables simultaneously. At the present time all these components are not completed due to time constraints. A robust tracking component of the controller for water level control is developed and its effectiveness on the parameter variations is demonstrated in this study. The results appear encouraging and they are only preliminary. Additional work is warranted to resolve other issues such as robust adaptive estimation.

  18. Simulation of a main steam line break with steam generator tube rupture using trace

    Energy Technology Data Exchange (ETDEWEB)

    Gallardo, S.; Querol, A.; Verdu, G. [Departamento de Ingenieria Quimica Y Nuclear, Universitat Politecnica de Valencia, Camino de Vera s/n, 46022, Valencia (Spain)

    2012-07-01

    A simulation of the OECD/NEA ROSA-2 Project Test 5 was made with the thermal-hydraulic code TRACE5. Test 5 performed in the Large Scale Test Facility (LSTF) reproduced a Main Steam Line Break (MSLB) with a Steam Generator Tube Rupture (SGTR) in a Pressurized Water Reactor (PWR). The result of these simultaneous breaks is a depressurization in the secondary and primary system in loop B because both systems are connected through the SGTR. Good approximation was obtained between TRACE5 results and experimental data. TRACE5 reproduces qualitatively the phenomena that occur in this transient: primary pressure falls after the break, stagnation of the pressure after the opening of the relief valve of the intact steam generator, the pressure falls after the two openings of the PORV and the recovery of the liquid level in the pressurizer after each closure of the PORV. Furthermore, a sensitivity analysis has been performed to know the effect of varying the High Pressure Injection (HPI) flow rate in both loops on the system pressures evolution. (authors)

  19. Matching the laser generated p bunch into a crossbar-H drift tube linac

    Science.gov (United States)

    Almomani, A.; Droba, M.; Ratzinger, U.; Hofmann, I.

    2012-05-01

    Proton bunches with energies up to 30 MeV have been measured at the PHELIX laser. Because of the laser-plasma interactions at a power density of about 4×1019W/cm2, a total yield of 1.5×1013protons was produced. For the reference energy of 10 MeV, the yield within ±0.5MeV was exceeding 1010protons. The important topic for a further acceleration of the laser generated bunch is the matching into the acceptance of an rf accelerator stage. With respect to the high space charge forces and the transit energy range, only drift tube linacs seem adequate for this purpose. A crossbar H-type (CH) cavity was chosen as the linac structure. Optimum emittance values for the linac injection are compared with the available laser generated beam parameters. Options for beam matching into a CH structure by a pulsed magnetic solenoid and by using the simulation codes LASIN and LORASR are presented.

  20. Video Captions for Online Courses: Do YouTube's Auto-Generated Captions Meet Deaf Students' Needs?

    Science.gov (United States)

    Parton, Becky Sue

    2016-01-01

    Providing captions for videos used in online courses is an area of interest for institutions of higher education. There are legal and ethical ramifications as well as time constraints to consider. Captioning tools are available, but some universities rely on the auto-generated YouTube captions. This study looked at a particular type of video--the…

  1. Creating a YouTube-Like Collaborative Environment in Mathematics: Integrating Animated Geogebra Constructions and Student-Generated Screencast Videos

    Science.gov (United States)

    Lazarus, Jill; Roulet, Geoffrey

    2013-01-01

    This article discusses the integration of student-generated GeoGebra applets and Jing screencast videos to create a YouTube-like medium for sharing in mathematics. The value of combining dynamic mathematics software and screencast videos for facilitating communication and representations in a digital era is demonstrated herein. We share our…

  2. A comprehensive flow-induced vibration model to predict crack growth and leakage potential in steam generator tubes

    Energy Technology Data Exchange (ETDEWEB)

    El Bouzidi, Salim [School of Engineering, University of Guelph, Guelph, Ontario N1G 2W1 (Canada); Hassan, Marwan, E-mail: mahassan@uoguelph.ca [School of Engineering, University of Guelph, Guelph, Ontario N1G 2W1 (Canada); Riznic, Jovica [Operational Engineering Assessment Division, Canadian Nuclear Safety Commission, Ottawa, Ontario K1P 5S9 (Canada)

    2015-10-15

    Highlights: • Comprehensive flow induced vibrations time domain model was developed. • Simulations of fluidelastic instability and turbulence were conducted. • Nonlinear effect due to the clearances at the supports was studied. • Prediction of stresses due to fluid excitation was obtained. • Deterministic and stochastic analyses for crack and leakage rate were conducted. - Abstract: Flow-induced vibrations (FIVs) are a major threat to the operation of nuclear steam generators. Turbulence and fluidelastic instability are the two main excitation mechanisms leading to tube vibrations. The consequences to the operation of steam generators are premature wear of the tubes, as well as development of cracks that may leak hazardous fluids. This paper investigates the effect of tube support clearance on the integrity of tube bundles within steam generators. Special emphasis will be placed on crack propagation and leakage rates. A crack growth model is used to simulate the growth of surface flaws and through-wall cracks of various initial sizes due to a wide range of support clearances. Leakage rates are predicted using a two-phase flow leakage model. Nonlinear finite element analysis is used to simulate a full U-bend subjected to fluidelastic and turbulence forces. Monte Carlo simulations are then used to conduct a probabilistic assessment of steam generator life due to crack development.

  3. One-Tube-Only Standardized Site-Directed Mutagenesis: An Alternative Approach to Generate Amino Acid Substitution Collections

    NARCIS (Netherlands)

    Mingo, J.; Erramuzpe, A.; Luna, S.; Aurtenetxe, O.; Amo, L.; Diez, I.; Schepens, J.T.G.; Hendriks, W.J.A.J.; Cortes, J.M.; Pulido, R.

    2016-01-01

    Site-directed mutagenesis (SDM) is a powerful tool to create defined collections of protein variants for experimental and clinical purposes, but effectiveness is compromised when a large number of mutations is required. We present here a one-tube-only standardized SDM approach that generates compreh

  4. Degradation of atrazine in aqueous medium by electrocatalytically generated hydroxyl radicals. A kinetic and mechanistic study.

    Science.gov (United States)

    Balci, Beytul; Oturan, Nihal; Cherrier, Richard; Oturan, Mehmet A

    2009-04-01

    Oxidative degradation of atrazine by hydroxyl radicals (()OH) was studied in aqueous medium. ()OH were formed in situ from electrochemically generating Fenton's reagent by an indirect electrochemical advanced oxidation process. Identification and evolution of seven main aromatic metabolites and four short-chain carboxylic acids were performed by using liquid chromatography analyses. Total organic carbon (TOC) and ionic chromatography were used in order to evaluate the mineralization efficiency of treated aqueous solutions. A high mineralization rate of 82% (never reported until now) was obtained. The oxidative degradation of cyanuric acid, the ultimate product of atrazine degradation, was highlighted for the first time. The absolute rate constant of the reaction between atrazine and hydroxyl radicals was evaluated by competition kinetics method as (2.54+/-0.22)x10(9)M(-1)s(-1). Considering all oxidation reaction intermediates and end products a general reaction sequence for atrazine degradation by hydroxyl radicals was proposed.

  5. Assessment of the leak tightness integrity of the steam generator tubes affected by ODSCC at the tube support plates

    Energy Technology Data Exchange (ETDEWEB)

    Cuvelliez, Ch.; Roussel, G. [AIB-Vincotte Nuclear, Brussels (Belgium)

    1997-02-01

    An EPRI report gives a method for predicting a conservative value of the total primary-to-secondary leak rate which may occur during, a postulated steam generator depressurization accident such as a Main Steam Line Break (MSLB) in a steam generator with axial through-wall ODSCC at the TSP intersections. The Belgian utility defined an alternative method deviating somewhat from the EPRI method. When reviewing this proposed method, the Belgian safety authorities performed some calculations to investigate its conservatism. This led them to recommend some modifications to the EPRI method which should reduce its undue conservatism while maintaining the objective of conservatism in the offsite dose calculations.

  6. Entropy generation in tube and fin radiating systems; Geracao de entropia em sistemas radiantes de tubos aletados

    Energy Technology Data Exchange (ETDEWEB)

    Santos, Marcio Bueno dos; Saboya, Sergio Mourao [Instituto Nacional de Pesquisas Espaciais (INPE), S Jose dos Campos, SP (Brazil). Lab. de Integracao e Testes]. E-mail: bueno@lit.inpe.br; saboya@mec.ita.cta.br

    1997-07-01

    The entropy generation minimization method is applied to tube and fin radiative systems. The mathematical modeling of the systems lead to a non-linear integro-differential systems of equations, which is solved numerically. The entropy generation in the fin is computed. This is obtained as result of the thermal analysis of the system which gives the fin temperature distributions and the radiative heat transfer rates. Examples of optimized design are considered and discussed. (author)

  7. Impulsively generated sausage waves in coronal tubes with transversally continuous structuring

    CERN Document Server

    Yu, Hui; Chen, Shao-Xia; Xiong, Ming; Guo, Ming-Zhe

    2016-01-01

    The frequency dependence of the longitudinal group speeds of trapped sausage waves plays an important role in determining impulsively generated wave trains, which have often been invoked to account for quasi-periodic signals in coronal loops. We examine how the group speeds ($v_{\\rm gr}$) depend on angular frequency ($\\omega$) for sausage modes in pressureless coronal tubes with continuous transverse density distributions by solving the dispersion relation pertinent to the case where the density inhomogeneity of arbitrary form takes place in a transition layer of arbitrary thickness. We find that in addition to the transverse lengthscale $l$ and density contrast $\\rho_{\\rm i}/\\rho_{\\rm e}$, the group speed behavior depends also on the detailed form of the density inhomogeneity. For parabolic profiles, $v_{\\rm gr}$ always decreases with $\\omega$ first before increasing again, as happens for the much studied top-hat profiles. For linear profiles, however, the behavior of the $\\omega-v_{\\rm gr}$ curves is more c...

  8. ANALISIS KEJADIAN STEAM GENERATOR TUBE RUPTURE (SGTR BERDASARKAN SKENARIO MIHAMA UNIT 2

    Directory of Open Access Journals (Sweden)

    Andi Sofrany Ekariansyah

    2015-03-01

    Full Text Available Pada tanggal 9 Februari 1991, terjadi kecelakaan putusnya pipa pemanas pembangkit uap (Steam Generator Tube Rupture/SGTR pada PLTN Mihama Unit 2. Dari kejadian tersebut, diperoleh catatan sekuensi kecelakaan berupa aktuasi sistem proteksi dan fitur keselamatan terekayasa dalam memitigasi kebocoran dari sistem primer ke sistem sekunder. Urutan sekuensi tersebut kemudian diterapkan pada PWR standar Jepang untuk disimulasikan menggunakan program perhitungan RELAP5/SCDAP/Mod3.2. Tujuannya untuk mengevaluasi konsekuensi yang terjadi bila kecelakaan tersebut terjadi pada PWR standar Jepang. Parameter yang dibandingkan adalah laju alir kebocoran, perubahan tekanan primer dan sekunder dan perubahan level di dalam pressurizer. Hasil simulasi menunjukkan perbedaan lama waktu kejadian SGTR hingga berhentinya kebocoran yang berlangsung lebih pendek pada PWR standar Jepang. Selain itu jumlah pendingin primer yang bocor dan jumlah uap yang terlepas dari MSRV tercatat lebih besar daripada PWR Mihama unit 2. Karakter aliran kebocoran, fluktuasi tekanan primer, dan level pressurizer sedikit berbeda pada tahap-tahap awal kejadian, namun relatif sama pada tahap akhir ketika aliran kebocoran dapat dihentikan. Hasil simulasi juga menunjukkan perlunya tindakan operator secara manual yang ditunjukkan dari isolasi sistem air umpan bantu (AFW pada pembangkit uap yang bocor, aktuasi katup pelepas uap (MSRV pada pembangkit uap yang utuh dan aktuasi auxiliary spray dan power operated relief valve (PORV pada pressurizer untuk mengantisipasi kejadian sebagai bagian dari prosedur operasi darurat. Kata kunci: SGTR, PWR Mihama Unit 2, PWR standar Jepang   On February 9,1991, a Steam Generator Tube Rupture (SGTR took place at the Mihama Unit No. 2. From that event, the accident sequence representing the actuation of protection system and engineered safety feature to mitigate the leak from primary system to secondary system is recorded. That sequence is then applied on the

  9. Measurement of Work Generation and Improvement in Performance of a Pulse Tube Engine

    Science.gov (United States)

    Hamaguchi, Kazuhiro; Futagi, Hiroaki; Yazaki, Taichi; Hiratsuka, Yoshikatsu

    Apart from double acting type engines, Stirling engines have either 2 pistons in 2 cylinders or 2 pistons in a single cylinder. Typically, the heater, regenerator and cooler are installed between the 2 pistons. The pulse tube engine, on the other hand, consists of a single piston in a single cylinder, a pulse tube, a heater, a regenerator, a cooler and a second cooler. For this paper, a simple prototype engine that uses air at normal atmospheric pressure as the working gas was fabricated. The oscillating velocity of the working gas in the pulse tube was measured using LDV, and the work flow emitting out of the pulse tube was observed. In addition, the effect of inserting heat storage material in the pulse tube on shaft power and indicated power was examined experimentally. A dramatic increase in the shaft power was achieved.

  10. Effect of humic acids on electricity generation integrated with xylose degradation in microbial fuel cells

    DEFF Research Database (Denmark)

    Huang, Liping; Angelidaki, Irini

    2008-01-01

    Pentose and humic acids (HA) are the main components of hydrolysates, the liquid fraction produced during thermohydrolysis of lignocellulosic material. Electricity generation integrated with xylose (typical pentose) degradation as well as the effect of HA on electricity production in microbial fu...

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

    Energy Technology Data Exchange (ETDEWEB)

    Yoshihisa Shindo; Kazuo Haga [Japan Nuclear Energy Safety Organization (JNES) Kamiya-cho MT Bldg., 4-3-20 Toranomon, Minato-ku, Tokyo 105-0001 (Japan)

    2005-07-01

    Full text of publication follows: A fundamental safety issue of liquid-metal-cooled fast breeder reactor (LMFBR) is to maintain the integrity of the secondary cooling system components against violent chemical sodium-water reaction caused by the water leak from the heat transfer tube of steam generators (SG). The produced sodium-water reaction jet would attack more severely surrounding tubes and would cause other tube failures (tube failure propagation), if it was assumed that the water leak was not detected by function-less detectors and proper operating actions to mitigate the tube failure propagation, such as isolations of the SG from the secondary cooling system and turbine water/steam system, and blowing water and steam inside tubes in the SG, were not taken. This study has been made focusing on the affection of large-scale water leak enlarged due to SG tube failure propagation to the structural integrity of the secondary cooling system because the generated pressure pulse caused by a large-scale sodium-water reaction might break heat transfer tubes of the intermediate heat exchanger (IHX). The present work has been made as one part of the study of probabilistic safety assessment (PSA) of LMFBR, because if the heat-transfer tubes of IHX were failed, the reactor core may be affected by the pressure pulse and/or by the sodium-water reaction products transported through the primary cooling system. As tools for PSA of the water leak incident of SG, we have developed QUARK-LP Version 4 code that mainly analyzes the high temperature rupture phenomena and estimates the number of failed tubes during the middle-scale water leak. The pressure pulse behavior generated by sodium-water reaction in the failure SG and the pressure propagation in the secondary cooling system are calculated by using the SWAAM-2 code developed by ANL. Furthermore, the quasi-steady state high pressure and temperature of the secondary cooling system in a long term is estimated by using the SWAAM

  12. Localization of defects in steam generator tubes using a multi-coil eddy current probe dedicated to high speed inspection

    Energy Technology Data Exchange (ETDEWEB)

    Joubert, P.-Y.; Le Bihan, Y.; Placko, D. [Ecole Normale Superieure de Cachan (France). Laboratoire d' Electricite Signaux et Robotique

    2002-07-01

    Steam generator (SG) tubing of pressurized water reactor in nuclear plants must be rapidly and accurately checked in order to detect defects in their early stages. In this paper, the authors present a multi-coil eddy current (EC) probe allowing both high speed inspection and circumferential localization of defects in the tube wall. A method of multi-coil EC signal processing, based on a continuous wavelet transform combined with a maximum likelihood diagnosis, is elaborated in order to enhance the detection performances and to provide automatic localization of defects. The inspection of SG tube samples shows good localization performances for defects as small as 10% deep, 15 mm long and 100 {mu}m wide outer diameter notches, of both circumferential and axial orientations. (author)

  13. Biodegradation of the alkaline cellulose degradation products generated during radioactive waste disposal.

    Science.gov (United States)

    Rout, Simon P; Radford, Jessica; Laws, Andrew P; Sweeney, Francis; Elmekawy, Ahmed; Gillie, Lisa J; Humphreys, Paul N

    2014-01-01

    The anoxic, alkaline hydrolysis of cellulosic materials generates a range of cellulose degradation products (CDP) including α and β forms of isosaccharinic acid (ISA) and is expected to occur in radioactive waste disposal sites receiving intermediate level radioactive wastes. The generation of ISA's is of particular relevance to the disposal of these wastes since they are able to form complexes with radioelements such as Pu enhancing their migration. This study demonstrates that microbial communities present in near-surface anoxic sediments are able to degrade CDP including both forms of ISA via iron reduction, sulphate reduction and methanogenesis, without any prior exposure to these substrates. No significant difference (n = 6, p = 0.118) in α and β ISA degradation rates were seen under either iron reducing, sulphate reducing or methanogenic conditions, giving an overall mean degradation rate of 4.7 × 10(-2) hr(-1) (SE ± 2.9 × 10(-3)). These results suggest that a radioactive waste disposal site is likely to be colonised by organisms able to degrade CDP and associated ISA's during the construction and operational phase of the facility.

  14. Biodegradation of the alkaline cellulose degradation products generated during radioactive waste disposal.

    Directory of Open Access Journals (Sweden)

    Simon P Rout

    Full Text Available The anoxic, alkaline hydrolysis of cellulosic materials generates a range of cellulose degradation products (CDP including α and β forms of isosaccharinic acid (ISA and is expected to occur in radioactive waste disposal sites receiving intermediate level radioactive wastes. The generation of ISA's is of particular relevance to the disposal of these wastes since they are able to form complexes with radioelements such as Pu enhancing their migration. This study demonstrates that microbial communities present in near-surface anoxic sediments are able to degrade CDP including both forms of ISA via iron reduction, sulphate reduction and methanogenesis, without any prior exposure to these substrates. No significant difference (n = 6, p = 0.118 in α and β ISA degradation rates were seen under either iron reducing, sulphate reducing or methanogenic conditions, giving an overall mean degradation rate of 4.7 × 10(-2 hr(-1 (SE ± 2.9 × 10(-3. These results suggest that a radioactive waste disposal site is likely to be colonised by organisms able to degrade CDP and associated ISA's during the construction and operational phase of the facility.

  15. Heat transfer enhancement accompanying pressure-loss reduction with winglet-type vortex generators for fin-tube heat exchangers

    Energy Technology Data Exchange (ETDEWEB)

    Torii, K.; Kwak, K.M.; Nishino, K. [Yokohama National Univ. (Japan). Dept. of Mechanical Engineering

    2002-08-01

    This paper proposes a novel technique that can augment heat transfer but nevertheless can reduce pressure-loss in a fin-tube heat exchanger with circular tubes in a relatively low Reynolds number flow, by deploying delta winglet-type vortex generators. The winglets are placed with a heretofore-unused orientation for the purpose of augmentation of heat transfer. This orientation is known as ''common flow up'' configuration. The proposed configuration causes significant separation delay, reduces form drag, and removes the zone of poor heat transfer from the near-wake of the tubes. This enhancement strategy has been successfully verified by experiments in the proposed configuration. In case of staggered tube banks, the heat transfer was augmented by 30% to 10%, and yet the pressure loss was reduced by 55% to 34% for the Reynolds number (based on two times channel height) ranging from 350 to 2100, when the present winglets were added. In case of in-line tube banks, these were found to be 20% to 10% augmentation, and 15% to 8% reduction, respectively. (author)

  16. Integrity evaluation for steam generator tube of system integrated modular advanced reactor

    Energy Technology Data Exchange (ETDEWEB)

    Kim, J. S.; Jin, T. E. [KOPEC, Taejon (Korea, Republic of); Jeong, M. J.; Choi, Y. H.; Jeo, J. C. [KINS, Taejon (Korea, Republic of)

    2003-10-01

    In this study, the structural integrity for SG tube of system integrated modular advanced reactor, which is subjected to dominant external pressure as well as helical type, is evaluated using the commercial finite element package ABAQUS and the American petrochemical industry code API 579 Appendix B. First of all, the crack behavior under the assumption of local heating is assessed using ABAQUS. And, the buckling behavior of tube with 40% wall thinning is assessed using API 579 Appendix B. As a result, it is found that the crack closure phenomenon occurs under external pressure and the buckling doesn't occur even if 40% wall thinning exists in tube.

  17. Impacts of environmental degradation and climate change on electricity generation in Malawi

    Energy Technology Data Exchange (ETDEWEB)

    Kaunda, Chiyembekezo S. [Department of Energy and Process Engineering – WaterPower Laboratory, Norway University of Science and Technology, Trondheim NO-7491 (Norway); Mtalo, Felix [Department of Water Resources Engineering, University of Dar es Salaam, P.O. Box 35031, Dar es Salaam (Tanzania, United Republic of)

    2013-07-01

    Hydropower is an important energy source in Malawi because it provides almost all of the country’s electricity generation capacity. This paper has reviewed the impacts of environmental degradation and climate change on hydropower generation in Malawi. Energy scenario and other issues that contribute towards the current state of environment have been discussed. All of Malawi’s hydropower stations are run-of-river schemes cascaded along the Shire River with an installed capacity of nearly 280 MW. The generation is impacted negatively by floods, siltation, droughts and aquatic weeds infestation. The way how these challenges are being exacerbated by the poor state of the environment, especially within the Shire River basin in particular is also discussed in the paper. Measures taken by the national electricity utility company on how to manage the impacts are discussed as well. The paper concludes that hydropower generation system in a highly environmental degraded area is difficult to manage both technically and economically. In the case of Malawi, diversifying to other energy sources of generating electricity is considered to be a viable option. Some mitigation measures concerning environment degradation and climate change challenges have been suggested in the paper.

  18. The influence of manufacturing processes on the microstructure, grain boundary characteristics and SCC behavior of Alloy 690 steam generator tubing

    Energy Technology Data Exchange (ETDEWEB)

    Sarver, J.M. [Babcock and Wilcox, Alliance, OH (United States). Research and Development Division; Doherty, P.E.; Doyle, D.M. [Babcock and Wilcox International Division, Cambridge, Ontario (Canada); Palumbo, G. [Ontario Hydro Technologies, Toronto, Ontario (Canada)

    1995-12-31

    Thermally treated Alloy 690 is the tubing material of choice for replacement steam generators in the United States. Throughout the world, it is manufactured using different melting and thermomechanical processing methods. The influence of different processing steps on the intergranular stress corrosion cracking (IGSCC) behavior of Alloy 690 has not been thoroughly evaluated. Evaluations were performed on Alloy 690 steam generator tubing produced using several different melting practices and thermomechanical processing procedures. The evaluations included extensive microstructural examinations as well as constant extension rate (CERT) tests. The CERT test results indicated that the thermally treated Alloy 690 tubing which was subjected to higher annealing temperatures displayed the highest degree of resistance to stress corrosion cracking (SCC). Examination of the microstructures indicated that the microstructural changes which are produced by increased annealing temperatures are subtle. In an attempt to further elucidate and quantify the effect of manufacturing processes on corrosion behavior, grain boundary character distribution (GBCD) measurements were performed on the same materials which were CERT tested. Analysis of GBCDs of the samples used in this study indicate that Alloy 690 exhibits a significantly larger fraction of special boundaries as compared to Alloy 600 and Alloy 800, regardless of the processing history of the tubing. Preliminary results indicate that a correlation may exist between processing method, GBCD`s and degree of IGSCC exhibited by the thermally treated samples examined in this study.

  19. Integration of an advanced sealed-tube neutron generator into a mobile neutron radiology system and resulting performance

    Science.gov (United States)

    Dance, William E.; Cluzeau, Serge; Mast, Hans-Ulrich

    1991-05-01

    The first DIANE ∗ neutron radiology system is being prepared for operation in the IABG laboratories in Ottobrunn (Germany). It utilizes a new D-T generator, designated GENIE 46, developed by SODERN (France) for this application. The generator is being integrated into an upgraded LTV-produced mobile neutron radiology system suitable for practical nonreactor inspection of components and structures. The maximum output of the present version of the GENIE 46 is 5 × 10 11 n s -1 (14 MeV) with less than 10 mA ion beam current at 225 kV. Tube lifetime at maximum output is approximately 500 h, while at 10 11 n s -1 the tube is designed for a lifetime of 1500 h. The geometry of the neutron tube, VHV connectors, ion source power supply, and cooling tubes comprises a cannister designed to be compatible with the 10-in. diameter opening in the LTV moderator/collimator assembly. 3-D Monte Carlo neutron/photon transport simulations of the new integrated radiology system operation have been performed by IABG. The calculations predict a thermal neutron flux at the collimator exit ( {L}/{D} = 13) of φth(0 ≤ En ≤ 0.3 eV) = 1.2 × 10 5 n cm -2 s -1. Comparisons of this value and other Monte Carlo results with actual performance will be made in the near future with the accrual of operational data.

  20. A REVIEW ON THE ODSCC OF STEAM GENERATOR TUBES IN KOREAN NPPS

    Directory of Open Access Journals (Sweden)

    HANSUB CHUNG

    2013-08-01

    Full Text Available The ODSCC detected in the TSP position of Ulchin 3&4 SGs are typical ODSCC of Alloy 600MA tubes. The causative chemical environment is formed by concentration of impurities inside the occluded region formed by the tube surface, egg crate strips, and sludge deposit there. Most cracks are detected at or near the line contacts between the tube surface and the egg crate strips. The region of dense crack population, as defined as between 4th and 9th TSPs, and near the center of hot leg hemisphere plane, coincided well with the region of preferential sludge deposition as defined by thermal hydraulics calculation using SGAP computer code. The cracks developed homogeneously in a wide range of SGs, so that the number of cracks detected each outage increased very rapidly since the first detection in the 8th refueling outage. The root cause assessment focused on investigation of the difference in microstructure and manufacturing residual stress in order to reveal the cause of different susceptibilities to ODSCC among identical six units. The manufacturing residual stress as measured by XRD on OD surface and by split tube method indicated that the high residual stress of Alloy 600MA tube played a critical role in developing ODSCC. The level of residual stress showed substantial variations among the six units depending on details of straightening and OD grinding processes. Youngwang 3&4 tubes are less susceptible to ODSCC than U3 and U4 tubes because semi-continuous coarse chromium carbides are formed along the grain boundary of Y3&4 tubes, while there are finer less continuous chromium carbides in U3 and U4. The different carbide morphology is caused by the difference in cooling rate after mill anneal. There is a possibility that high chromium content in the Y3&4 tubes, still within the allowable range of Alloy 600, has made some contribution to the improved resistance to ODSCC. It is anticipated that ODSCC in Y5&6 SGs will be retarded more considerably

  1. A Fundamental study of remedial technology development to prevent stress corrosion cracking of steam generator tubing

    Energy Technology Data Exchange (ETDEWEB)

    Park, In Gyu; Lee, Chang Soon [Sunmoon University, Asan (Korea)

    1998-04-01

    Most of the PWR Steam generators with tubes in Alloy 600 alloy are affected by Stress Corrosion Cracking, such as PWSCC(Primary Water Stress Corrosion Cracking) and ODSCC(Outside Diameter Stress Corrosion Cracking). This study was undertaken to establish the background for remedial technology development to prevent SCC. in the report are included the following topics: (1) General: (i) water chemistry related factors, (ii) Pourbaix(Potential-pH) Diagram, (iii) polarization plot, (iv) corrosion mode of Alloy 600, 690, and 800, (v) IGA/SCC growth rate, (vi) material suspetibility of IGA/SCC, (vii) carbon solubility of Alloy 600 (2) Microstructures of Alloy 600 MA, Alloy 600 TT, Alloy 600 SEN Alloy 690 TT(Optical, SEM, and TEM) (3) Influencing factors for PWSCC initiation rate of Alloy 600: (i) microstructure, (ii) water chemistry(B, Li), (iii) temperature, (iv) plastic deformation, (v) stress relief annealing (4) Influencing factors for PWSCC growth rate of Alloy 600: (i) water chemistry(B, Li), (ii) Scott Model, (iii) intergranular carbide, (iv) temperature, (v) hold time (5) Laboratory conditions for ODSCC initiation rate: 1% NaOH, 316 deg C; 1% NaOH, 343 deg C; 50% NaOH, 288 deg C; 10% NaOH, 302 deg C; 10% NaOH, 316 deg C; 50% NaOH, 343 deg C (6) Sludge effects for ODSCC initiation rate: CuO, Cr{sub 2}O{sub 3}, Fe{sub 3}O{sub 4} (7) Influencing factors for PWSCC growth rate of Alloy 600: (i) Caustic concentration effect, (ii) carbonate addition effect (8) Sulfate corrosion: (i) sulfate ratio and pH effect, (ii) wastage rate of Alloy 600 and Alloy 690 (9) Crevice corrosion: (i) experimental setup for crevice corrosion, (ii) organic effect, (iii) (Na{sub 2}SO{sub 4} + NaOH) effect (10) Remedial measures for SCC: (i) Inhibitors, (ii) ZnO effect. (author). 30 refs., 174 figs., 51 tabs.

  2. Kinetics of substrate degradation and electricity generation in anodic denitrification microbial fuel cell (AD-MFC).

    Science.gov (United States)

    Zhang, Jiqiang; Zheng, Ping; Zhang, Meng; Chen, Hui; Chen, Tingting; Xie, Zuofu; Cai, Jing; Abbas, Ghulam

    2013-12-01

    Effect of substrate concentration on substrate degradation and electricity generation in anodic denitrification microbial fuel cell (AD-MFC) was investigated over a broad range of substrate concentrations. Substrate degradation rates and power generation could be promoted with increasing substrate concentration in a certain range, but both of them would be inhibited at high substrate concentrations. Maximum denitrification rate of 1.26 ± 0.01 kg NO(-)-N/m(3)d and maximum output voltage of 1016.75 ± 4.74 mV could be achieved when initial NO3(-)-N concentration was 1999.95 ± 2.86 mg/L. Based on Han-Levenspiel model, kinetics of substrate degradation and power generation in the AD-MFC were established. According to the kinetic model, the half-saturation coefficient and the critical inhibitory concentration for nitrate were more than 200 and 4300 mg/L, respectively. The results demonstrated that AD-MFC was capable of treating nitrate-containing wastewater and generating electricity simultaneously, and tolerant to high strength nitrate-containing wastewater.

  3. Exergy destruction analysis of a vortices generator in a gas liquid finned tube heat exchanger: an experimental study

    Science.gov (United States)

    Ghazikhani, M.; Khazaee, I.; Monazzam, S. M. S.; Takdehghan, H.

    2016-11-01

    In the present work, the effect of using different shapes of vortices generator (VG) on a gas liquid finned heat exchanger is investigated experimentally with irreversibility analysis. In this project the ambient air with mass flow rates of 0.047-0.072 kg/s is forced across the finned tube heat exchanger. Hot water with constant flow rate of 240 L/h is circulated inside heat exchanger tubes with inlet temperature range of 45-73 °C. The tests are carried out on the flat finned heat exchanger and then repeated on the VG finned heat exchanger. The results show that using the vortex generator can decrease the ratio of air side irreversibility to heat transfer (ASIHR) of the heat exchanger. Also the results show that the IASIHR is >1.05 for all air mass flow rates, which means that ASIHR for the initial heat exchanger is higher than 5 % greater than that of improved heat exchanger.

  4. Degradation of Phenol in Wastewater with Ozone Produced by Self-design Ozone Generator

    Directory of Open Access Journals (Sweden)

    Wang Shibo

    2016-01-01

    Full Text Available The optimized tube’s structure of the self-design ozone generator was made with the double dielectric inner electrode and small metal cones were embedded in the outside electrode. This ozone generator was used for the degradation of phenol in wastewater. The research was studied from ozone gas flow rate, reaction time, the initial pH and concentration of the phenol in wastewater. In addition, the article also discusses the reaction mechanism of ozone degraded the phenol in wastewater. The results illustrate that the ozone concentration of self-design ozone generator under the pure oxygen flux (1.0 L/min were 7.06 mg/L, compared with the unoptimized ozone, the optimized ozone generator’s efficiency was improved 56.89%; the phenol removal rate was increased as the initial pH increased in wastewater, when pH was 12, the phenol removal rate was 80.17%; GC-MS analysis was adopted to analyze and determine the phenol intermediates. The results illustrate that the major oxidation degradation products of phenol may be p-benzoquinone benzenequinone, 4-cyclopentene-1, 3-dione and diacetone alcohol.

  5. J-resistance curves for Inconel 690 and Incoloy 800 nuclear steam generators tubes at room temperature and at 300 °C

    Science.gov (United States)

    Bergant, Marcos A.; Yawny, Alejandro A.; Perez Ipiña, Juan E.

    2017-04-01

    The structural integrity of steam generator tubes is a relevant issue concerning nuclear plant safety. In the present work, J-resistance curves of Inconel 690 and Incoloy 800 nuclear steam generator tubes with circumferential and longitudinal through wall cracks were obtained at room temperature and 300 °C using recently developed non-standard specimens' geometries. It was found that Incoloy 800 tubes exhibited higher J-resistance curves than Inconel 690 for both crack orientations. For both materials, circumferential cracks resulted into higher fracture resistance than longitudinal cracks, indicating a certain degree of texture anisotropy introduced by the tube fabrication process. From a practical point of view, temperature effects have found to be negligible in all cases. The results obtained in the present work provide a general framework for further application to structural integrity assessments of cracked tubes in a variety of nuclear steam generator designs.

  6. [Electricity generation and contaminants degradation performances of a microbial fuel cell fed with Dioscorea zingiberensis wastewater].

    Science.gov (United States)

    Li, Hui; Zhu, Xiu-Ping; Xu, Nan; Ni, Jin-Ren

    2011-01-01

    The electricity generation performance of a microbial fuel cell (MFC) utilizing Dioscorea zingiberensis wastewater was studied with an H-shape reactor. Indexes including pH, conductivity, oxidation peak potential and chemical oxygen demand (COD) of the anolyte were monitored to investigate the contaminants degradation performance of the MFC during the electricity generation process, besides, contaminant ingredients in anodic influent and effluent were analyzed by GC-MS and IR spectra as well. The maximum power density of the MFC could achieve 118.1 mW/m2 and the internal resistance was about 480 omega. Connected with a 1 000 omega external resistance, the output potential was about 0.4 V. Fed with 5 mL Dioscorea zingiberensis wastewater, the electricity generation lasted about 133 h and the coulombic efficiency was about 3.93%. At the end of electricity generation cycle, COD decreased by 90.1% while NH4(+) -N decreased by 66.8%. Furfural compounds, phenols and some other complicated organics could be decomposed and utilized in the electricity generation process, and the residual contaminants in effluent included some long-chain fatty acids, esters, ethers, and esters with benzene ring, cycloalkanes, cycloolefins, etc. The results indicate that MFC, which can degrade and utilize the organic contaminants in Dioscorea zingiberensis wastewater simultaneously, provides a new approach for resource recovery treatment of Dioscorea zingiberensis wastewater.

  7. YouTube as a Qualitative Research Asset: Reviewing User Generated Videos as Learning Resources

    Science.gov (United States)

    Chenail, Ronald J.

    2011-01-01

    YouTube, the video hosting service, offers students, teachers, and practitioners of qualitative researchers a unique reservoir of video clips introducing basic qualitative research concepts, sharing qualitative data from interviews and field observations, and presenting completed research studies. This web-based site also affords qualitative…

  8. On the entropy generation in the Ranque-Hilsch tube; Zur Entropieproduktion im Ranque-Hilsch-Rohr

    Energy Technology Data Exchange (ETDEWEB)

    Mischner, J. [Fachhochschule Erfurt (Germany). Fachbereich Versorgungstechnik, Lehrgebiet Gas - und Abgastechnik; Bespalov, V.I. [Staatliche Bauuniversitaet Rostow am Don (Russian Federation). Lehrstuhl fuer Umweltingenieurwesen

    2002-05-01

    Starting from the entropy generation in vortex tubes, this paper presents a new approach for simulating the Ranque-Hilsch effect. It can be stated that the systematic description of energy separation in the vortex tube (process simulation on the basis of the ''separation approach'') describes all essential phenomenological characteristics of the Ranque-Hilsch effect (typical temperature variation, dependencies of the separation effect on the input parameters and others) correctly with respect to quantity and quality. Moreover, the hydrodynamic process variables are related to the geometrical characteristics of the vortex tube via the ROSSBY number. In the authors opinion, this is the first proposal for calculating vortex tubes to represent the physical findings in a self-consistent way without elementary empirical assumptions, deriving the gas dynamic and thermodynamic process variables as well as basic geometrical parameters of the vortex tube apparatus one by one in their interrelationship. The ideal-gas model presented can be applied to real gases. (orig.) [German] Im vorliegenden Beitrag wird ausgehend von der Entropieproduktion in Wirbelrohren ein neuer Ansatz zur Modellierung des Ranque- Hilsch-Effektes vorgestellt. Die entwickelte Beschreibung des Separationseffektes im Wirbelrohr (Prozessmodell auf der Basis des ''Separationsansatzes'') beschreibt alle wesentlichen phaenomenologischen Merkmale des Ranque- Hilsch-Effektes (typische Temperaturverlaeufe, Abhaengigkeiten des Separationseffektes von den Eingangsparametern usw.) quantitativ und qualitativ korrekt. Die hydrodynamischen Prozessgroessen sind ueber die Rossby-Zahl mit den geometrischen Charakteristika des Wirbelrohres verknuepft. Nach Ansicht der Verfasser liegt hiermit der erste Vorschlag zur Berechnung von Wirbelrohren vor, der ohne fundamentale empirische Annahmen die physikalischen Befunde in sich konsistent abbildet, die gas- und thermodynamischen

  9. Characterization of radiolytically generated degradation products in the strip section of a TRUEX flowsheet

    Energy Technology Data Exchange (ETDEWEB)

    Dean R. Peterman; Lonnie G. Olson; Gary S. Groenewold; Rocklan G. McDowell; Richard D. Tillotson; Jack D. Law

    2013-08-01

    This report presents a summary of the work performed to meet the FCRD level 2 milestone M3FT-13IN0302053, “Identification of TRUEX Strip Degradation.” The INL radiolysis test loop has been used to identify radiolytically generated degradation products in the strip section of the TRUEX flowsheet. These data were used to evaluate impact of the formation of radiolytic degradation products in the strip section upon the efficacy of the TRUEX flowsheet for the recovery of trivalent actinides and lanthanides from acidic solution. The nominal composition of the TRUEX solvent used in this study is 0.2 M CMPO and 1.4 M TBP dissolved in n-dodecane and the nominal composition of the TRUEX strip solution is 1.5 M lactic acid and 0.050 M diethylenetriaminepentaacetic acid. Gamma irradiation of a mixture of TRUEX process solvent and stripping solution in the test loop does not adversely impact flowsheet performance as measured by stripping americium ratios. The observed increase in americium stripping distribution ratios with increasing absorbed dose indicates the radiolytic production of organic soluble degradation compounds.

  10. BIOLOGICAL PERFORMANCE OF A DEGRADABLE POLY(LACTIC ACID-EPSILON-CAPROLACTONE) NERVE GUIDE - INFLUENCE OF TUBE DIMENSIONS

    NARCIS (Netherlands)

    DENDUNNEN, WFA; VANDERLEI, B; ROBINSON, PH; HOLWERDA, A; PENNINGS, AJ; SCHAKENRAAD, JM

    1995-01-01

    One of the ways to reconstruct a nerve defect is to use a biodegradable nerve guide. The aim of this study was to establish a nerve guide constructed of an amorphous copolymer of lactic acid-caprolactone. A pilot study was set up to elucidate the effect of the tube dimensions on nerve regeneration.

  11. Hydrogen peroxide generation and photocatalytic degradation of estrone by microstructural controlled ZnO nanorod arrays

    Energy Technology Data Exchange (ETDEWEB)

    Liu Yangsi; Han Jie; Qiu Wei [Department of Chemical and Materials Engineering, The University of Auckland, Private Bag 92019, Auckland 1142 (New Zealand); Gao Wei, E-mail: w.gao@auckland.ac.nz [Department of Chemical and Materials Engineering, The University of Auckland, Private Bag 92019, Auckland 1142 (New Zealand)

    2012-12-15

    Highlights: Black-Right-Pointing-Pointer H{sub 2}O{sub 2} generated by ZnO nanorod arrays during UV irradiation was detected. Black-Right-Pointing-Pointer ZnO nanorod arrays were synthesized via a facile hydrothermal technique. Black-Right-Pointing-Pointer The microstructure can be controlled by varying reactants' concentration. Black-Right-Pointing-Pointer Photocatalytic degradation of estrone by ZnO nanorod arrays was studied. Black-Right-Pointing-Pointer Microstructures' effect on photocatalysis and H{sub 2}O{sub 2} generation was discussed. - Abstract: The strong oxidant, hydrogen peroxide (H{sub 2}O{sub 2}), generated by ZnO nanorod arrays under UV light irradiation was monitored by fluorescence analysis. The ZnO nanorod arrays were synthesized via a low temperature hydrothermal method and their dimensions, i.e., diameter and height, can be controlled by adjusting the concentration of zinc nitrate (Zn(NO{sub 3}){sub 2}{center_dot}6H{sub 2}O) and hexamethylenetetramine (HMT). The morphology, nanostructure, surface roughness and optical property were characterized by scanning electron microscopy (SEM), X-ray diffraction (XRD), atomic force microscopy (AFM) and transmittance spectra, respectively. The ZnO nanorod arrays were applied in the degradation of estrone, which is an emerging steroid estrogen contaminant. The results revealed that the ZnO nanorod array produced from 25 mM Zn{sup 2+} and HMT had the highest aspect ratio, the largest surface roughness and the lowest band gap energy, which was beneficial to the efficiency of UV light utilization, photocatalytic degradation of estrone and H{sub 2}O{sub 2} generation.

  12. ''Risk safety of high frequency fatigue rupture for the vapor generators tubes''; ''Prevention du risque de rupture par fatigue vibratoire des tubes de generateurs de vapeur''

    Energy Technology Data Exchange (ETDEWEB)

    Solgadi, E.; Le Duff, J.A. [FRAMATOME, 92 - Paris-La-Defense (France); Bussy, B. [Electricite de France, 75 - Paris (France). Service Etudes et Projets Thermiques et Nucleaires

    2001-07-01

    Among the different rupture ways identified since 1975 for the steam generators tubes, the fatigue damage occurred on four cases. Two of them are analyzed in this paper: the NORTH ANNA 1 and the MIHAMA 2. From these analysis, it appears that the fatigue crack happens with aggravating factors as the tube embedding, the anti-vibration bars or fretting corrosion. As a preventive, the number of anti-vibration bars has been increase for the vapor generators 1300 and a new system of damper has been developed and implemented on the vapor generator 900. (A.L.B.)

  13. Degradation of organic gases using ultrasonic mist generated from TiO2 suspension.

    Science.gov (United States)

    Sekiguchi, Kazuhiko; Noshiroya, Daisuke; Handa, Misako; Yamamoto, Keisuke; Sakamoto, Kazuhiko; Namiki, Norikazu

    2010-09-01

    The photocatalytic degradation of organic gases with mist particles that were formed by ultrasonic atomization of a TiO(2) suspension was performed with three different ultraviolet light sources. Three aromatic volatile organic compounds (VOCs; toluene, p-xylene, and styrene) and aldehydes (formaldehyde and acetaldehyde) were chosen as model organic gases for the degradation experiment. Under UV(365) irradiation, toluene was decomposed by a photocatalytic reaction on the surface of mist particles. Under UV(254+185) irradiation, the removal efficiency and mineralization ratio of the VOC gases were higher than those under UV(365) or UV(254) irradiation. Under UV(254+185) irradiation, it was found that VOC gases were immediately degraded and converted to water-soluble intermediates by not only direct photolysis but also oxidation by OH radical, since the removal efficiency of several organic gases depended on the reaction rate with OH radical and the primary effect of generated ozone was to complete the mineralization of the intermediates. On the other hand, water-soluble aldehyde gases were rapidly trapped by mist particles before reaction on their surface. Furthermore, water-soluble intermediates that formed via the decomposition of VOC gases were completely trapped in the mist and were not detected at the reactor exit. Therefore, notable secondary particle generation was not observed, even under UV(254+185) irradiation. Based on these results as well as the size distribution of the mist droplets, it was found that primarily submicron-scale droplets contributed to the photocatalytic reaction. Lastly, we propose a mechanism for the degradation of organic gaseous pollutants on the surface of mist particles.

  14. Influence of supporting electrolyte in electricity generation and degradation of organic pollutants in photocatalytic fuel cell.

    Science.gov (United States)

    Khalik, Wan Fadhilah; Ong, Soon-An; Ho, Li-Ngee; Wong, Yee-Shian; Voon, Chun-Hong; Yusuf, Sara Yasina; Yusoff, Nik Athirah; Lee, Sin-Li

    2016-08-01

    This study investigated the effect of different supporting electrolyte (Na2SO4, MgSO4, NaCl) in degradation of Reactive Black 5 (RB5) and generation of electricity. Zinc oxide (ZnO) was immobilized onto carbon felt acted as photoanode, while Pt-coated carbon paper as photocathode was placed in a single chamber photocatalytic fuel cell, which then irradiated by UV lamp for 24 h. The degradation and mineralization of RB5 with 0.1 M NaCl rapidly decreased after 24-h irradiation time, followed by MgSO4, Na2SO4 and without electrolyte. The voltage outputs for Na2SO4, MgSO4 and NaCl were 908, 628 and 523 mV, respectively, after 24-h irradiation time; meanwhile, their short-circuit current density, J SC, was 1.3, 1.2 and 1.05 mA cm(-2), respectively. The power densities for Na2SO4, MgSO4 and NaCl were 0.335, 0.256 and 0.245 mW cm(-2), respectively. On the other hand, for without supporting electrolyte, the voltage output and short-circuit current density was 271.6 mV and 0.055 mA cm(-2), respectively. The supporting electrolyte NaCl showed greater performance in degradation of RB5 and generation of electricity due to the formation of superoxide radical anions which enhance the degradation of dye. The mineralization of RB5 with different supporting electrolyte was measured through spectrum analysis and reduction in COD concentration.

  15. Improved Performance of an Indigenous Stirling Type Pulse Tube Cooler and Pressure Wave Generator

    Science.gov (United States)

    Kumar, J. Kranthi; Jacob, S.; Karunanithi, R.; Narasimham, G. S. V. L.; Damu, C.; Praveen, T.; Samir, M.

    Sustained efforts have been made in our laboratory to improve the performance of an indigenously developed pressure wave gen- erator by reducing the mechanical losses and the required input power. An acoustically matching pulse tube cooler, with a design target of 0.5 W at 80 K, was designed using Sage and experience gained from previous studies. The pulse tube cooler was fabri- cated and tested. The effect of regenerator stacking pattern on the cooler performance was studied by filling the regenerator with mesh of the same size #400 and with multi meshes #250, 325, 400. In present experiments, regenerator with #400 mesh at 30 bar filling pressure performed better with more energy efficiency. A no load temperature of 74 K was achieved with input power of 59 W corresponding to a cooling power of 0.22 W at 80 K. Parasitic heat load to the cooler was measured be 0.68 W. This heat load is primarily by heat conduction through the regenerator and pulse tube wall. By reducing the wall thickness from 0.30 mm to 0.15 mm, the parasitic loads can be reduced by 50%.

  16. Generation and Propagation of Finite-Amplitude Waves in Flexible Tubes (A)

    DEFF Research Database (Denmark)

    Jensen, Leif Bjørnø

    1972-01-01

    Highly reproducible finite-amplitude waves, generated by a modified electromagnetic plane-wave generator, characterized by a rise time......Highly reproducible finite-amplitude waves, generated by a modified electromagnetic plane-wave generator, characterized by a rise time...

  17. Enhancement of heat transfer and entropy generation analysis of nanofluids turbulent convection flow in square section tubes

    Directory of Open Access Journals (Sweden)

    Bianco Vincenzo

    2011-01-01

    Full Text Available Abstract In this article, developing turbulent forced convection flow of a water-Al2O3 nanofluid in a square tube, subjected to constant and uniform wall heat flux, is numerically investigated. The mixture model is employed to simulate the nanofluid flow and the investigation is accomplished for particles size equal to 38 nm. An entropy generation analysis is also proposed in order to find the optimal working condition for the given geometry under given boundary conditions. A simple analytical procedure is proposed to evaluate the entropy generation and its results are compared with the numerical calculations, showing a very good agreement. A comparison of the resulting Nusselt numbers with experimental correlations available in literature is accomplished. To minimize entropy generation, the optimal Reynolds number is determined.

  18. Enhancement of heat transfer and entropy generation analysis of nanofluids turbulent convection flow in square section tubes.

    Science.gov (United States)

    Bianco, Vincenzo; Nardini, Sergio; Manca, Oronzio

    2011-03-24

    In this article, developing turbulent forced convection flow of a water-Al2O3 nanofluid in a square tube, subjected to constant and uniform wall heat flux, is numerically investigated. The mixture model is employed to simulate the nanofluid flow and the investigation is accomplished for particles size equal to 38 nm.An entropy generation analysis is also proposed in order to find the optimal working condition for the given geometry under given boundary conditions. A simple analytical procedure is proposed to evaluate the entropy generation and its results are compared with the numerical calculations, showing a very good agreement.A comparison of the resulting Nusselt numbers with experimental correlations available in literature is accomplished. To minimize entropy generation, the optimal Reynolds number is determined.

  19. Steady Secondary Flows Generated by Periodic Compression and Expansion of an Ideal Gas in a Pulse Tube

    Science.gov (United States)

    Lee, Jeffrey M.

    1999-01-01

    This study establishes a consistent set of differential equations for use in describing the steady secondary flows generated by periodic compression and expansion of an ideal gas in pulse tubes. Also considered is heat transfer between the gas and the tube wall of finite thickness. A small-amplitude series expansion solution in the inverse Strouhal number is proposed for the two-dimensional axisymmetric mass, momentum and energy equations. The anelastic approach applies when shock and acoustic energies are small compared with the energy needed to compress and expand the gas. An analytic solution to the ordered series is obtained in the strong temperature limit where the zeroth-order temperature is constant. The solution shows steady velocities increase linearly for small Valensi number and can be of order I for large Valensi number. A conversion of steady work flow to heat flow occurs whenever temperature, velocity or phase angle gradients are present. Steady enthalpy flow is reduced by heat transfer and is scaled by the Prandtl times Valensi numbers. Particle velocities from a smoke-wire experiment were compared with predictions for the basic and orifice pulse tube configurations. The theory accurately predicted the observed steady streaming.

  20. Differential geometry based model for eddy current inspection of U-bend sections in steam generator tubes

    Science.gov (United States)

    Mukherjee, Saptarshi; Rosell, Anders; Udpa, Lalita; Udpa, Satish; Tamburrino, Antonello

    2017-02-01

    The modeling of U-Bend segment in steam generator tubes for predicting eddy current probe signals from cracks, wear and pitting in this region poses challenges and is non-trivial. Meshing the geometry in the cartesian coordinate system might require a large number of elements to model the U-bend region. Also, since the lift-off distance between the probe and tube wall is usually very small, a very fine mesh is required near the probe region to accurately describe the eddy current field. This paper presents a U-bend model using differential geometry principles that exploit the result that Maxwell's equations are covariant with respect to changes of coordinates and independent of metrics. The equations remain unaltered in their form, regardless of the choice of the coordinates system, provided the field quantities are represented in the proper covariant and contravariant form. The complex shapes are mapped into simple straight sections, while small lift-off is mapped to larger values, thus reducing the intrinsic dimension of the mesh and stiffness matrix. In this contribution, the numerical implementation of the above approach will be discussed with regard to field and current distributions within the U-bend tube wall. For the sake of simplicity, a two dimensional test case will be considered. The approach is evaluated in terms of efficiency and accuracy by comparing the results with that obtained using a conventional FE model in cartesian coordinates.

  1. Statistical analysis of entropy generation in longitudinally finned tube heat exchanger with shell side nanofluid by a single phase approach

    Science.gov (United States)

    Konchada, Pavan Kumar; Pv, Vinay; Bhemuni, Varaprasad

    2016-06-01

    The presence of nanoparticles in heat exchangers ascertained increment in heat transfer. The present work focuses on heat transfer in a longitudinal finned tube heat exchanger. Experimentation is done on longitudinal finned tube heat exchanger with pure water as working fluid and the outcome is compared numerically using computational fluid dynamics (CFD) package based on finite volume method for different flow rates. Further 0.8% volume fraction of aluminum oxide (Al2O3) nanofluid is considered on shell side. The simulated nanofluid analysis has been carried out using single phase approach in CFD by updating the user-defined functions and expressions with thermophysical properties of the selected nanofluid. These results are thereafter compared against the results obtained for pure water as shell side fluid. Entropy generated due to heat transfer and fluid flow is calculated for the nanofluid. Analysis of entropy generation is carried out using the Taguchi technique. Analysis of variance (ANOVA) results show that the inlet temperature on shell side has more pronounced effect on entropy generation.

  2. Statistical analysis of entropy generation in longitudinally finned tube heat exchanger with shell side nanofluid by a single phase approach

    Directory of Open Access Journals (Sweden)

    Konchada Pavan Kumar

    2016-06-01

    Full Text Available The presence of nanoparticles in heat exchangers ascertained increment in heat transfer. The present work focuses on heat transfer in a longitudinal finned tube heat exchanger. Experimentation is done on longitudinal finned tube heat exchanger with pure water as working fluid and the outcome is compared numerically using computational fluid dynamics (CFD package based on finite volume method for different flow rates. Further 0.8% volume fraction of aluminum oxide (Al2O3 nanofluid is considered on shell side. The simulated nanofluid analysis has been carried out using single phase approach in CFD by updating the user-defined functions and expressions with thermophysical properties of the selected nanofluid. These results are thereafter compared against the results obtained for pure water as shell side fluid. Entropy generated due to heat transfer and fluid flow is calculated for the nanofluid. Analysis of entropy generation is carried out using the Taguchi technique. Analysis of variance (ANOVA results show that the inlet temperature on shell side has more pronounced effect on entropy generation.

  3. Gaseous products generated by radiation degradation of N,N-diethylhydroxylamine aqueous solution

    Institute of Scientific and Technical Information of China (English)

    WANG Jinhua; WANG Shengxiu; BAO Borong; LI Zhen; LI Chun; ZHENG Weifang; ZHANG Shengdong

    2008-01-01

    In this paper, gaseous products generated by radiation degradation of N,N-diethylhydroxylamine (DEHA)in aqueous solution are studied. The results show that by 10~1000 kGy irradiation of the solution in DEHA volume fraction of hydrogen did not change much with different concentrations of DEHA. The volume fraction of methane and ethane decreased, but that of ethene increased, with increasing DEHA concentration. The volume fraction of hydrogen, methane and ethane increased with the dose. The relationship of the volume fraction of ethene with the dose had something to do with the DEHA concentration.

  4. Oxide Dispersion Strengthened Fe(sub 3)Al-Based Alloy Tubes: Application Specific Development for the Power Generation Industry

    Energy Technology Data Exchange (ETDEWEB)

    Kad, B.K.

    1999-07-01

    A detailed and comprehensive research and development methodology is being prescribed to produce Oxide Dispersion Strengthened (ODS)-Fe3Al thin walled tubes, using powder extrusion methodologies, for eventual use at operating temperatures of up to 1100C in the power generation industry. A particular 'in service application' anomaly of Fe3Al-based alloys is that the environmental resistance is maintained up to 1200C, well beyond where such alloys retain sufficient mechanical strength. Grain boundary creep processes at such high temperatures are anticipated to be the dominant failure mechanism.

  5. Heat transfer characteristics and entropy generation for wing-shaped-tubes with longitudinal external fins in cross-flow

    Energy Technology Data Exchange (ETDEWEB)

    Ahmed, Sayed Ahmed E. Sayed; Mesalhy, Osama M.; Abdelatief, Mohamed A. [Zagazig University, Zagazig (Egypt)

    2016-06-15

    A numerical study is conducted to clarify heat transfer characteristics, effectiveness and entropy generation for a bundle of wingshaped-tubes attached to Longitudinal fins (LF) at downstream side. The air-side Re{sub a} ranged from 1.8 x 10{sup 3} to 9.7 x 10{sup 3} . The fin height (h{sub f}) and fin thickness (δ) have been changed as: (2 mm <= hf <= 12 mm) and (1.5 mm <= δ <= 3.5 mm). The analysis of entropy generation is based on the principle of minimizing the rate of total entropy generation that includes the generation of entropy due to heat transfer and friction losses. The temperature field around the wing-shaped-tubes with (LF) is predicted using commercial CFD FLUENT 6.3.26 software package. Correlations of Nu{sub a}, St{sub a}, and Bejan number (Be), as well as the irreversibility distribution ratio (Φ) in terms of Re{sub a} and design parameters for the studied bundle are presented. Results indicated that, installing fins with heights from 2 to 12 mm results in an increase in Nu{sub a} from 11 to 36% comparing with that of wing-shaped tubes without fins (NOF). The highest and lowest values of effectiveness(ε) at every value of the considered Re{sub a} range are occurred at hf = 6 mm and (NOF), espectively. The wing-shaped-tubes heat exchanger with hf = 6 mm has the highest values of (ε), efficiency index (η) and area goodness factor (G{sub a}) and also the lowest values of Φ and hence the best performance comparing with other arrangements. The minimum values of Φ are occurred at hf = 6 mm. (Be) decreases with increasing Re{sub a} for all studied hf. The heat transfer irreversibility predominates for (1800 <= Re{sub a} <= 4200) while the opposite is true for (6950 < Re{sub a} <= 9700). δ has negligible effect on Nu{sub a} and heat transfer irreversibility. Comparisons between the experimental and numerical results of the present study and those, previously, obtained for similar available studies showed good agreements.

  6. Structural integrity analysis of the degraded drywell containment at the Oyster Creek Nuclear generating station.

    Energy Technology Data Exchange (ETDEWEB)

    Petti, Jason P.

    2007-01-01

    This study examines the effects of the degradation experienced in the steel drywell containment at the Oyster Creek Nuclear Generating Station. Specifically, the structural integrity of the containment shell is examined in terms of the stress limits using the ASME Boiler and Pressure Vessel (B&PV) Code, Section III, Division I, Subsection NE, and examined in terms of buckling (stability) using the ASME B&PV Code Case N-284. Degradation of the steel containment shell (drywell) at Oyster Creek was first observed during an outage in the mid-1980s. Subsequent inspections discovered reductions in the shell thickness due to corrosion throughout the containment. Specifically, significant corrosion occurred in the sandbed region of the lower sphere. Since the presence of the wet sand provided an environment which supported corrosion, a series of analyses were conducted by GE Nuclear Energy in the early 1990s. These analyses examined the effects of the degradation on the structural integrity. The current study adopts many of the same assumptions and data used in the previous GE study. However, the additional computational recourses available today enable the construction of a larger and more sophisticated structural model.

  7. Exact solution of unsteady flow generated by sinusoidal pressure gradient in a capillary tube

    Directory of Open Access Journals (Sweden)

    M. Abdulhameed

    2015-12-01

    Full Text Available In this paper, the mathematical modeling of unsteady second grade fluid in a capillary tube with sinusoidal pressure gradient is developed with non-homogenous boundary conditions. Exact analytical solutions for the velocity profiles have been obtained in explicit forms. These solutions are written as the sum of the steady and transient solutions for small and large times. For growing times, the starting solution reduces to the well-known periodic solution that coincides with the corresponding solution of a Newtonian fluid. Graphs representing the solutions are discussed.

  8. Electrochemical degradation of the antibiotic sulfachloropyridazine by hydroxyl radicals generated at a BDD anode.

    Science.gov (United States)

    Haidar, Mariam; Dirany, Ahmad; Sirés, Ignasi; Oturan, Nihal; Oturan, Mehmet A

    2013-05-01

    The treatment of aqueous solutions of the antibiotic sulfachloropyridazine (SCP) was carried out at the natural pH of the solution (pH 4.5) with hydroxyl radicals (OH) generated at a BDD anode surface by electro-oxidation using an undivided electrochemical cell equipped with a three-dimensional carbon-felt cathode. Hydroxyl radicals are powerful oxidants and react with the antibiotic leading to its overall mineralization. The kinetic study showed that oxidative degradation of SCP follows pseudo first-order reaction kinetics, with a relatively short degradation time. The degree of mineralization of SCP solutions increased with the applied current, being higher than 95% after 8 h of electrolysis at 350 mA or higher current. To determine the degradation pathway upon the action of hydroxyl radicals, the cyclic and aliphatic by-products, as well as the released inorganic ions, were identified and quantified over electrolysis time. The values of the rate constants of reactions between OH and the SCP and its intermediates were determined by the competition kinetics method using p-hydroxybenzoic acid. The absolute rate constant for the OH-mediated degradation of SCP was found to be 1.92 × 10(9)M(-1)s(-1). Toxicity assessment by the Microtox method during the electro-oxidation of SCP solutions revealed the formation of compounds that can be more toxic than the parent molecule, but the overall results confirm the effectiveness of this electrochemical process for the removal of the antibiotic SCP and its by-products from aqueous media. Copyright © 2013 Elsevier Ltd. All rights reserved.

  9. Neuraminidase-Dependent Degradation of Polysialic Acid Is Required for the Lamination of Newly Generated Neurons.

    Directory of Open Access Journals (Sweden)

    Mari Sajo

    Full Text Available Hippocampal granule cells (GCs are generated throughout the lifetime and are properly incorporated into the innermost region of the granule cell layer (GCL. Hypotheses for the well-regulated lamination of newly generated GCs suggest that polysialic acid (PSA is present on the GC surface to modulate GC-to-GC interactions, regulating the process of GC migration; however, direct evidence of this involvement is lacking. We show that PSA facilitates the migration of newly generated GCs and that the activity of N-acetyl-α-neuraminidase 1 (NEU1, sialidase 1 cleaves PSA from immature GCs, terminating their migration in the innermost GCL. Developing a migration assay of immature GCs in vitro, we found that the pharmacological depletion of PSA prevents the migration of GCs, whereas the inhibition of PSA degradation with a neuraminidase inhibitor accelerates this migration. We found that NEU1 is highly expressed in immature GCs. The knockdown of NEU1 in newly generated GCs in vivo increased PSA presence on these cells, and attenuated the proper termination of GC migration in the innermost GCL. In conclusion, this study identifies a novel mechanism that underlies the proper lamination of newly generated GCs through the modulation of PSA presence by neuronal NEU1.

  10. Neuraminidase-Dependent Degradation of Polysialic Acid Is Required for the Lamination of Newly Generated Neurons.

    Science.gov (United States)

    Sajo, Mari; Sugiyama, Hiroki; Yamamoto, Hideaki; Tanii, Takashi; Matsuki, Norio; Ikegaya, Yuji; Koyama, Ryuta

    2016-01-01

    Hippocampal granule cells (GCs) are generated throughout the lifetime and are properly incorporated into the innermost region of the granule cell layer (GCL). Hypotheses for the well-regulated lamination of newly generated GCs suggest that polysialic acid (PSA) is present on the GC surface to modulate GC-to-GC interactions, regulating the process of GC migration; however, direct evidence of this involvement is lacking. We show that PSA facilitates the migration of newly generated GCs and that the activity of N-acetyl-α-neuraminidase 1 (NEU1, sialidase 1) cleaves PSA from immature GCs, terminating their migration in the innermost GCL. Developing a migration assay of immature GCs in vitro, we found that the pharmacological depletion of PSA prevents the migration of GCs, whereas the inhibition of PSA degradation with a neuraminidase inhibitor accelerates this migration. We found that NEU1 is highly expressed in immature GCs. The knockdown of NEU1 in newly generated GCs in vivo increased PSA presence on these cells, and attenuated the proper termination of GC migration in the innermost GCL. In conclusion, this study identifies a novel mechanism that underlies the proper lamination of newly generated GCs through the modulation of PSA presence by neuronal NEU1.

  11. On the possibility for laboratory simulation of generation of Alfven disturbances in magnetic tubes in the solar atmosphere

    Science.gov (United States)

    Prokopov, Pavel; Zaharov, Yuriy; Tishchenko, Vladimir; Boyarintsev, Eduard; Melehov, Aleksandr; Ponomarenko, Arnold; Posuh, Vitaliy; Shayhislamov, Ildar

    2016-03-01

    The paper deals with generation of Alfven plasma disturbances in magnetic flux tubes through exploding laser plasma in magnetized background plasma. Processes with similar effect of excitation of torsion-type waves seem to provide energy transfer from the solar photosphere to corona. The studies were carried out at experimental stand KI-1 represented a high-vacuum chamber of 1.2 m diameter, 5 m long, external magnetic field up to 500 Gs along the chamber axis, and up to 2×10^-6 Torr pressure in operating mode. Laser plasma was produced when focusing the CO2 laser pulse on a flat polyethylene target, and then the laser plasma propagated in θ-pinch background hydrogen (or helium) plasma. As a result, the magnetic flux tube of 15-20 cm radius was experimentally simulated along the chamber axis and the external magnetic field direction. Also, the plasma density distribution in the tube was measured. Alfven wave propagation along the magnetic field was registered from disturbance of the magnetic field transverse component B_ψ and field-aligned current J_z. The disturbances propagate at near-Alfven velocity of 70-90 km/s and they are of left-hand circular polarization of the transverse component of magnetic field. Presumably, Alfven wave is generated by the magnetic laminar mechanism of collisionless interaction between laser plasma cloud and background. The right-hand polarized high-frequency whistler predictor was registered which have been propagating before Alfven wave at 300 km/s velocity. The polarization direction changed with Alfven wave coming. Features of a slow magnetosonic wave as a sudden change in background plasma concentration along with simultaneous displacement of the external magnetic field were found. The disturbance propagates at ~20-30 km/s velocity, which is close to that of ion sound at low plasma beta value. From preliminary estimates, the disturbance transfers about 10 % of the original energy of laser plasma.

  12. Multi-region fuzzy logic controller with local PID controllers for U-tube steam generator in nuclear power plant

    Directory of Open Access Journals (Sweden)

    Puchalski Bartosz

    2015-12-01

    Full Text Available In the paper, analysis of multi-region fuzzy logic controller with local PID controllers for steam generator of pressurized water reactor (PWR working in wide range of thermal power changes is presented. The U-tube steam generator has a nonlinear dynamics depending on thermal power transferred from coolant of the primary loop of the PWR plant. Control of water level in the steam generator conducted by a traditional PID controller which is designed for nominal power level of the nuclear reactor operates insufficiently well in wide range of operational conditions, especially at the low thermal power level. Thus the steam generator is often controlled manually by operators. Incorrect water level in the steam generator may lead to accidental shutdown of the nuclear reactor and consequently financial losses. In the paper a comparison of proposed multi region fuzzy logic controller and traditional PID controllers designed only for nominal condition is presented. The gains of the local PID controllers have been derived by solving appropriate optimization tasks with the cost function in a form of integrated squared error (ISE criterion. In both cases, a model of steam generator which is readily available in literature was used for control algorithms synthesis purposes. The proposed multi-region fuzzy logic controller and traditional PID controller were subjected to broad-based simulation tests in rapid prototyping software - Matlab/Simulink. These tests proved the advantage of multi-region fuzzy logic controller with local PID controllers over its traditional counterpart.

  13. Oxide Dispersion Strengthened Fe3Al-Based Alloy Tubes: Application Specific Development for the Power Generation Industry

    Energy Technology Data Exchange (ETDEWEB)

    Kad, B.K.

    2002-02-08

    A detailed and comprehensive research and development methodology is being prescribed to produce Oxide Dispersion Strengthened (ODS)-Fe{sub 3}Al thin walled tubes, using powder extrusion methodologies, for eventual use at operating temperatures of up to 1100% in the power generation industry. A particular ''in service application'' anomaly of Fe{sub 3}Al-based alloys is that the environmental resistance is maintained up to 1200 C, well beyond where such alloys retain sufficient mechanical strength. Grain boundary creep processes at such high temperatures are anticipated to be the dominant failure mechanism. Thus, the challenges of this program are manifold: (1) to produce thin walled ODS-Fe{sub 3}Al tubes, employing powder extrusion methodologies, with (2) adequate increased strength for service at operating temperatures, and (3) to mitigate creep failures by enhancing the as-processed grain size in ODS-Fe{sub 3}Al tubes. Our research progress till date has resulted in the successful batch production of typically 8 Ft. lengths of 1-3/8 inch diameter, 1/8 inch wall thickness, ODS-Fe{sub 3}Al tubes via a proprietary single step extrusion consolidation process. The process parameters for such consolidation methodologies have been prescribed and evaluated as being routinely reproducible. Such processing parameters (i.e., extrusion ratios, temperature, can design etc.) were particularly guided by the need to effect post-extrusion recrystallization and grain growth at a sufficiently low temperature, while still meeting the creep requirement at service temperatures. Static recrystallization studies show that elongated grains (with their long axis parallel to the extrusion axis), typically 200-2000 {micro}m in diameter, and several millimeters long can be obtained routinely, at 1200 C. The growth kinetics are affected by the interstitial impurity content in the powder batches. For example complete recrystallization, across the tube wall thickness, is

  14. Investigation of the effect of a bend in a transfer line that separates a pulse tube cold head and a pressure wave generator

    Science.gov (United States)

    Dev, A. A.; Atrey, M. D.; Vanapalli, S.

    2017-02-01

    A transfer line between a pulse tube cold head and a pressure wave generator is usually required to isolate the cold head from the vibrations of the compressor. Although it is a common practice to use a thin and narrow straight tube, a bent tube would allow design flexibility and easy mounting of the cold head, such as in a split Stirling type pulse tube cryocooler. In this paper, we report a preliminary investigation on the effect of the bending of the tube on the flow transfer characteristics. A numerical study using commercial computational fluid dynamics model is performed to gain insight into the flow characteristics in the bent tube. Oscillating flow experiments are performed with a straight and a bent tube at a filling pressure of 15 bar and an operating frequency of 40, 50 and 60 Hz. The data and the corresponding numerical simulations point to the hypothesis that the secondary flow in the bent tube causes a decrease in flow at a fixed pressure amplitude.

  15. Potential of pulsed corona discharges generated in water for the degradation of persistent pharmaceutical residues.

    Science.gov (United States)

    Banaschik, Robert; Lukes, Petr; Jablonowski, Helena; Hammer, Malte U; Weltmann, Klaus-Dieter; Kolb, Juergen F

    2015-11-01

    Anthropogenic pollutants and in particular pharmaceutical residues are a potential risk for potable water where they are found in increasing concentrations. Different environmental effects could already be linked to the presence of pharmaceuticals in surface waters even for low concentrations. Many pharmaceuticals withstand conventional water treatment technologies. Consequently, there is a need for new water purification techniques. Advanced oxidation processes (AOP), and especially plasmas with their ability to create reactive species directly in water, may offer a promising solution. We developed a plasma reactor with a coaxial geometry to generate large volume corona discharges directly in water and investigated the degradation of seven recalcitrant pharmaceuticals (carbamazepine, diatrizoate, diazepam, diclofenac, ibuprofen, 17α-ethinylestradiol, trimethoprim). For most substances we observed decomposition rates from 45% to 99% for treatment times of 15-66 min. Especially ethinylestradiol and diclofenac were readily decomposed. As an inherent advantage of the method, we found no acidification and only an insignificant increase in nitrate/nitrite concentrations below legal limits for the treatment. Studies on the basic plasma chemical processes for the model system of phenol showed that the degradation is primarily caused by hydroxyl radicals.

  16. The tubular MFC with carbon tube air-cathode for power generation and N,N-dimethylacetamide treatment.

    Science.gov (United States)

    Liu, Jiadong; Liu, Lifen; Gao, Bo

    2016-01-01

    A continuous flow microbial fuel cell (MFC) was assembled with carbon tube air-cathode and carbon felt anode. The organic solvent N,N-dimethylacetamide (DMAC) was used as the only carbon source for power generation. After the adaptive phase, the cell potential was gradually increased from 0.15 to 0.45 V with 200 Ω of external resistor during 150 h of operation. The calculated power density of this MFC was 100 mW L(-1) when the cell potential was 0.45 V. The reversible redox peaks of carbon tube were obtained in cyclic voltammogram between -0.5 and -0.25 V under aerobic circumstance. The removal rate of DMAC was 15-50% after treatment with hydraulic retention time of 12 min. The results indicated that it is possible to realize the power extraction from DMAC wastewater in the form of electricity by the bioconversion process of MFC.

  17. Microfluidic generation and selective degradation of biopolymer-based Janus microbeads.

    Science.gov (United States)

    Marquis, Mélanie; Renard, Denis; Cathala, Bernard

    2012-04-09

    We describe a microfluidic approach for generating Janus microbeads from biopolymer hydrogels. A flow-focusing device was used to emulsify the coflow of aqueous solutions of one or two different biopolymers in an organic phase to synthesize homo or hetero Janus microbeads. Biopolymer gelation was initiated, in the chip, by diffusion-controlled ionic cross-linking of the biopolymers. Pectin-pectin (homo Janus) and, for the first time, pectin-alginate (hetero Janus) microbeads were produced. The efficiency of separation of the two hemispheres, which reflected mixing and convection phenomena, was investigated by confocal scanning laser microscopy (CSLM) of previously labeled biopolymers. The interface of the hetero Janus structure was clearly defined, whereas that of the homo Janus microbeads was poorly defined. The Janus structure was confirmed by subjecting each microbead hemisphere to specific enzymatic degradation. These new and original microbeads from renewable resources will open up opportunities for studying relationships between combined enzymatic hydrolysis and active compound release.

  18. Heat transfer and pressure drop characteristics of the tube bank fin heat exchanger with fin punched with flow redistributors and curved triangular vortex generators

    Science.gov (United States)

    Liu, Song; Jin, Hua; Song, KeWei; Wang, LiangChen; Wu, Xiang; Wang, LiangBi

    2017-10-01

    The heat transfer performance of the tube bank fin heat exchanger is limited by the air-side thermal resistance. Thus, enhancing the air-side heat transfer is an effective method to improve the performance of the heat exchanger. A new fin pattern with flow redistributors and curved triangular vortex generators is experimentally studied in this paper. The effects of the flow redistributors located in front of the tube stagnation point and the curved vortex generators located around the tube on the characteristics of heat transfer and pressure drop are discussed in detail. A performance comparison is also carried out between the fins with and without flow redistributors. The experimental results show that the flow redistributors stamped out from the fin in front of the tube stagnation points can decrease the friction factor at the cost of decreasing the heat transfer performance. Whether the combination of the flow redistributors and the curved vortex generators will present a better heat transfer performance depends on the size of the curved vortex generators. As for the studied two sizes of vortex generators, the heat transfer performance is promoted by the flow redistributors for the fin with larger size of vortex generators and the performance is suppressed by the flow redistributors for the fin with smaller vortex generators.

  19. Computationally generated velocity taper for efficiency enhancement in a coupled-cavity traveling-wave tube

    Science.gov (United States)

    Wilson, Jeffrey D.

    1989-01-01

    A computational routine has been created to generate velocity tapers for efficiency enhancement in coupled-cavity TWTs. Programmed into the NASA multidimensional large-signal coupled-cavity TWT computer code, the routine generates the gradually decreasing cavity periods required to maintain a prescribed relationship between the circuit phase velocity and the electron-bunch velocity. Computational results for several computer-generated tapers are compared to those for an existing coupled-cavity TWT with a three-step taper. Guidelines are developed for prescribing the bunch-phase profile to produce a taper for efficiency. The resulting taper provides a calculated RF efficiency 45 percent higher than the step taper at center frequency and at least 37 percent higher over the bandwidth.

  20. Turbulent wind field characterization and re-generation based on pitot tube measurements mounted on a wind turbine

    DEFF Research Database (Denmark)

    Pedersen, Mads Mølgaard; Larsen, Torben J.; Aagaard Madsen, Helge;

    2015-01-01

    This paper describes a new method to estimate the undisturbed inflow field of a wind turbine based on measurements obtained from one or more five-hole pitot tubes mounted directly on the blades. Based on the measurements, the disturbance caused by the wind turbine is estimated using aerodymanic...... the measured wind speeds at the recording position. In the theoretical part of this study a quite good agreement is seen between load sensors on a turbine model exposed to the reference and the re-generated turbulence field. Finally the method is applied to full scale measurements and reasonable wind shear...... profiles are derived. It is expected that this method will lead to a new and effective experimental method to characterize the incoming flow field to a wind turbine and thus contribute to the understanding of wind turbine loads....

  1. Analysis of two-phase flow instability in helical tube steam generator in high temperature gas cooled reactor

    Energy Technology Data Exchange (ETDEWEB)

    Yu, Yu; Lv, Xuefeng; Wang, Shengfei; Niu, Fenglei; Tian, Li [North China Electric Power Univ., Beijing (Switzerland)

    2012-03-15

    The steam generator composed of multi-helical tubes is used in high temperature gas cooled reactors and two-phase flow instability should be avoided in design. And density-wave oscillation which is mainly due to flow, density and the relationship between the pressure drop delays and feedback effects is one of the two-phase flow instability phenomena easily to occur. Here drift-flux model is used to simulate the performance of the fluid in the secondary side and frequency domain and time domain methods are used to evaluate whether the density-wave oscillation will happen or not. Several operating conditions with nominal power from 15% to 30% are calculated in this paper. The results of the two methods are in accordance, flow instability will occur when power is less than 20% nominal power, which is also according with the result of the experiments well.

  2. Removal of lead from cathode ray tube funnel glass by generating the sodium silicate.

    Science.gov (United States)

    Hu, Biao; Zhao, Shuangshuang; Zhang, Shuhao

    2015-01-01

    In the disposal of electronic waste, cathode ray tube (CRT) funnel glass is an environmental problem of old television sets. Removal of the lead from CRT funnel glass can prevent its release into the environment and allow its reuse. In this research, we reference the dry progress productive technology of sodium silicate, the waste CRT glass was dealt with sodium silicate frit melted and sodium silicate frit dissolved. Adding a certain amount of Na ₂CO₃to the waste CRT glass bases on the material composition and content of it, then the specific modulus of sodium silicate frit is obtained by melting progress. The silicon, potassium and sodium compounds of the sodium silicate frit are dissolved under the conditions of high temperature and pressure by using water as solvent, which shows the tendency that different temperature, pressure, liquid-solid ratio and dissolving time have effect on the result of dissolving. At 175°C(0.75MPa), liquid-solid ratio is 1.5:1, the dissolving time is 1h, the dissolution rate of sodium silicate frit is 44.725%. By using sodium sulfide to separate hydrolysis solution and to collect lead compounds in the solution, the recovery rate of lead in dissolving reached 100% and we can get clean sodium silicate and high purity of lead compounds. The method presented in this research can recycle not only the lead but also the sodium, potassium and other inorganic minerals in CRT glass and can obtain the comprehensive utilization of leaded glass.

  3. Boiler tube failures in industrial drum-type steam generators. Pt. 3: Alternative cycle chemistry treatments

    Energy Technology Data Exchange (ETDEWEB)

    Bursik, A. [University of Stuttgart (Germany)

    2002-12-01

    This part (the third part of a four-part publication) discusses the applicability of amine-based plant cycle treatments which are covered neither by the VGB Guideline for Boiler Feedwater, Boiler Water, and Steam of Steam Generators with a Permissible Operating Pressure of >6.8 MPa nor by the set of EPRI Cycle Chemistry Guidelines for Fossil Plants. (orig.)

  4. [Power generation from glucose and nitrobenzene degradation using the microbial fuel cell].

    Science.gov (United States)

    Li, Jie; Liu, Guang-Li; Zhang, Ren-Duo; Luo, Yong; Zhang, Cui-Ping; Li, Ming-Chen; Quan, Xiang-Chun

    2010-11-01

    By constructing a dual-chamber microbial fuel cell (MFC), experiments were carried out using an initial glucose concentration of 1 000 mg/L with different nitrobenzene (NB) concentrations (0, 50, 150 and 250 mg/L) as the MFC's fuel. Results showed that with an external resistance of 1 000 omega, the initial glucose concentration of 1 000 mg/L and the initial NB concentrations of 0, 50, 150, 250 mg/L, the operation periods were 55.7, 51.6, 45.9 and 32.2 h, respectively, the maximum voltage outputs were 670, 597, 507, and 489 mV, the maximum volumetric power densities were 28.57, 20.42, 9.29, and 8.47 W/m3, and the electric charges were 65.10, 43.50, 35.48, and 30.32 C. The MFC could use the NB and glucose mixtures as fuel and generated stable electricity outputs. The degradation rates of NB in the MFC in all cases reached up to 100% and COD removals in the MFC were 87% - 98%. However, the electricity generation was negligible when using 250 mg/L NB as the sole fuel. Denaturing gradient gel electrophoresis (DGGE) profiles demonstrated that the presence of NB resulted in changes of the dominant bacterial species on the electrodes.

  5. Evaluation of a sodium-water reaction event caused by steam generator tubes break in the prototype generation IV sodium-cooled fast reactor

    Energy Technology Data Exchange (ETDEWEB)

    Ahn, Sang June; Ha, Kwi Seok; Chang, Won Pyo; Kang, Seok Hun; Lee, Kwi Lim; Choi, Chi Woong; Lee, Seung Won; Yoo, Jin; Jeong, Jae Ho; Jeong, Tae Kyeong [Korea Atomic Energy Research Institute, Daejeon (Korea, Republic of)

    2016-08-15

    The prototype generation IV sodium-cooled fast reactor (PGSFR) has been developed by the Korea Atomic Energy Research Institute. This reactor uses sodium as a reactor coolant to transfer the core heat energy to the turbine. Sodium has chemical characteristics that allow it to violently react with materials such as a water or steam. When a sodium–water reaction (SWR) occurs due to leakage or breakage of steam generator tubes, high-pressure waves and corrosive reaction products are produced, which threaten the structural integrity of the components of the intermediate heat-transfer system (IHTS) and the safety of the primary heat-transfer system (PHTS). In the PGSFR, SWR events are included in the design-basis event. This event should be analyzed from the viewpoint of the integrities of the IHTS and fuel rods. To evaluate the integrity of the IHTS based on the consequences of the SWR, the behaviors of the generated high-pressure waves are analyzed at the major positions of a failed IHTS loop using a sodium–water advanced analysis method-II code. The integrity of the fuel rods must be consistently maintained below the safety acceptance criteria to avoid the consequences of the SWR. The integrity of the PHTS is evaluated using the multidimensional analysis of reactor safety-liquid metal reactor code to model the whole plant.

  6. Coincident steam generator tube rupture and stuck-open safety relief valve carryover tests: MB-2 steam generator transient response test program

    Energy Technology Data Exchange (ETDEWEB)

    Garbett, K; Mendler, O J; Gardner, G C; Garnsey, R; Young, M Y

    1987-03-01

    In PWR steam generator tube rupture (SGTR) faults, a direct pathway for the release of radioactive fission products can exist if there is a coincident stuck-open safety relief valve (SORV) or if the safety relief valve is cycled. In addition to the release of fission products from the bulk steam generator water by moisture carryover, there exists the possibility that some primary coolant may be released without having first mixed with the bulk water - a process called primary coolant bypassing. The MB-2 Phase II test program was designed specifically to identify the processes for droplet carryover during SGTR faults and to provide data of sufficient accuracy for use in developing physical models and computer codes to describe activity release. The test program consisted of sixteen separate tests designed to cover a range of steady-state and transient fault conditions. These included a full SGTR/SORV transient simulation, two SGTR overfill tests, ten steady-state SGTR tests at water levels ranging from very low levels in the bundle up to those when the dryer was flooded, and three moisture carryover tests without SGTR. In these tests the influence of break location and the effect of bypassing the dryer were also studied. In a final test the behavior with respect to aerosol particles in a dry steam generator, appropriate to a severe accident fault, was investigated.

  7. Efficient peroxydisulfate activation process not relying on sulfate radical generation for water pollutant degradation

    KAUST Repository

    Zhang, Tao

    2014-05-20

    Peroxydisulfate (PDS) is an appealing oxidant for contaminated groundwater and toxic industrial wastewaters. Activation of PDS is necessary for application because of its low reactivity. Present activation processes always generate sulfate radicals as actual oxidants which unselectively oxidize organics and halide anions reducing oxidation capacity of PDS and producing toxic halogenated products. Here we report that copper oxide (CuO) can efficiently activate PDS under mild conditions without producing sulfate radicals. The PDS/CuO coupled process is most efficient at neutral pH for decomposing a model compound, 2,4-dichlorophenol (2,4-DCP). In a continuous-flow reaction with an empty-bed contact time of 0.55 min, over 90% of 2,4-DCP (initially 20 μM) and 90% of adsorbable organic chlorine (AOCl) can be removed at the PDS/2,4-DCP molar ratio of 1 and 4, respectively. Based on kinetic study and surface characterization, PDS is proposed to be first activated by CuO through outer-sphere interaction, the rate-limiting step, followed by a rapid reaction with 2,4-DCP present in the solution. In the presence of ubiquitous chloride ions in groundwater/industrial wastewater, the PDS/CuO oxidation shows significant advantages over sulfate radical oxidation by achieving much higher 2,4-DCP degradation capacity and avoiding the formation of highly chlorinated degradation products. This work provides a new way of PDS activation for contaminant removal. © 2014 American Chemical Society.

  8. Diagnostic examination of Generation 2 lithium-ion cells and assessment ofperformance degradation mechanisms.

    Energy Technology Data Exchange (ETDEWEB)

    Abraham, D. P.; Dees, D. W.; Knuth, J.; Reynolds, E.; Gerald, R.; Hyung,Y.-E.; Belharouak, I.; Stoll, M.; Sammann, E.; MacLaren, S.; Haasch, R.; Twesten,R.; Sardela, M.; Battaglia, V.; Cairns, E.; Kerr, J.; Kerlau, M.; Kostecki, R.; Lei,J.; McCarthy, K.; McLarnon, F.; Reimer, J.; Richardson, T.; Ross, P.; Sloop,S.; Song, X.; Zhuang, V.; Balasubramanian, M.; McBreen, J.; Chung, K.-Y.; Yang, X.Q.; Yoon, W.-S.; Norin, L.

    2005-07-15

    The Advanced Technology Development (ATD) Program is a multilaboratory effort to assist industrial developers of high-power lithium-ion batteries overcome the barriers of cost, calendar life, abuse tolerance, and low-temperature performance so that this technology may be rendered practical for use in hybrid electric vehicles (HEVs). Included in the ATD Program is a comprehensive diagnostics effort conducted by researchers at Argonne National Laboratory (ANL), Brookhaven National Laboratory (BNL), and Lawrence Berkeley National Laboratory (LBNL). The goals of this effort are to identify and characterize processes that limit lithium-ion battery performance and calendar life, and ultimately to describe the specific mechanisms that cause performance degradation. This report is a compilation of the diagnostics effort conducted since spring 2001 to characterize Generation 2 ATD cells and cell components. The report is divided into a main body and appendices. Information on the diagnostic approach, details from individual diagnostic techniques, and details on the phenomenological model used to link the diagnostic data to the loss of 18650-cell electrochemical performance are included in the appendices. The main body of the report includes an overview of the 18650-cell test data, summarizes diagnostic data and modeling information contained in the appendices, and provides an assessment of the various mechanisms that have been postulated to explain performance degradation of the 18650 cells during accelerated aging. This report is intended to serve as a ready reference on ATD Generation 2 18650-cell performance and provide information on the tools for diagnostic examination and relevance of the acquired data. A comprehensive account of our experimental procedures and resulting data may be obtained by consulting the various references listed in the text. We hope that this report will serve as a roadmap for the diagnostic analyses of other lithium-ion technologies being

  9. Hologram recording tubes

    Science.gov (United States)

    Rajchman, J. H.

    1973-01-01

    Optical memories allow extremely large numbers of bits to be stored and recalled in a matter of microseconds. Two recording tubes, similar to conventional image-converting tubes, but having a soft-glass surface on which hologram is recorded, do not degrade under repeated hologram read/write cycles.

  10. APSTNG: Associated particle sealed-tube neutron generator studies for arms control. Final report on NN-20 Project ST220

    Energy Technology Data Exchange (ETDEWEB)

    Rhodes, E.; Dickerman, C.E.; Brunner, T.; Hess, A.; Tylinski, S.

    1994-12-01

    Argonne National Laboratory has performed research and development on the use of Associated Particle Sealed-Tube Neutron Generator (APSTNG) technology for treaty verification and non-proliferation applications, under funding from the DOE Office of Nonproliferation and National Security. Results indicate that this technology has significant potential for nondestructively detecting elemental compositions inside inspected objects or volumes. The final phase of this project was placement of an order for commercial procurement of an advanced sealed tube, with its high-voltage supply and control systems. Procurement specifications reflected lessons learned during the study. The APSTNG interrogates a volume with a continuous 14-MeV neutron flux. Each neutron is emitted coincident with an {open_quotes}associated{close_quotes} alpha-particle emitted in the opposite direction. Thus detection of an alpha-particle marks the emission of a neutron in a cone opposite to that defined by the alpha detector. Detection of a gamma ray coincident with the alpha indicates that the gamma was emitted from a neutron-induced reaction inside the neutron cone: the gamma spectra can be used to identify fissionable materials and many isotopes having an atomic number larger than that of boron. The differences in gamma-ray and alpha-particle detection times yield a coarse measurement of the distance along the cone axis from the APSTNG emitter to each region containing the identified nuclide. A position-sensitive alpha detector would permit construction of coarse three-dimensional images. The source and emission-detection systems can be located on the same side of the interrogated volume. The neutrons and gamma rays are highly penetrating. A relatively high signal-to-background ratio allows the use of a relatively small neutron source and conventional electronics.

  11. Performance Degradation of the Repeated Recycled Aggregate Concrete with 70% Replacement of Three-generation Recycled Coarse Aggregate

    Institute of Scientific and Technical Information of China (English)

    ZHU Pinghua; ZHANG Xinxin; WU Junyong; WANG Xinjie

    2016-01-01

    The feasibility of using different generations recycled coarse aggregate (RCA) on structural concrete was fully evaluated by studying the performance of the recycled coarse aggregates and their corresponding concretes, the different generations of RCA were recycled by following the repeated mode of ‘concrete-waste concrete-coarse aggregate-concrete’. Moreover, the focus was on ‘three generations’ of repeated RCAs, the RCA was produced by crushing and regenerating the artiifcial accelerated degraded concrete, the process was designed to follow the nature degradation of the concrete with a coupling action of accelerated carbonation and bending load. The properties ofx-generation (x=1, 2 or 3) of repeated RCA were systematically investigated and the compressive and splitting tensile strengths of relating structural concretes(with 70% replacement ofx-generation of RCA) were studied accordingly. The results show a competent compressive and splitting tensile strength of 30 MPa at 28th day of structural concretes with all generations of repeated RAC. And the gradual degraded performance of the repeated RCAs was observed with an increased numbers of repetition (1﹥2﹥3 generations), the overall performances of all repeated RCAs fulifll the ClassⅢaccording to Chinese Standards GB25177-2010. Our gained insight demonstrates a feasibility of using at least 3 generations of repeated RCA for the production of normal structural concrete.

  12. Degradation of phenol solution by ozone oxidation in a microporous tube-in-tube microchannel reactor%采用套管式微反应器臭氧氧化降解苯酚水溶液的研究

    Institute of Scientific and Technical Information of China (English)

    李鹏飞; 李文军; 王洁欣; 付纪文; 陈建峰; 邵磊

    2011-01-01

    将新型套管式微反应器应用于苯酚溶液的臭氧氧化处理体系,考察了套管式微反应器微孔孔径、内外管环隙、苯酚溶液初始质量浓度、温度、pH值和气液比等因素对苯酚去除率的影响.结果表明,苯酚去除率随着套管微孔孔径、内外管环隙和苯酚溶液初始质量浓度的增大而减小;随着气液比和温度的增大而增大;而随着溶液pH值的增大,苯酚去除率则先增大后减小.初始质量浓度为100mg/L的苯酚溶液在pH为11,气液比为13,套管内管孔径为10μm,内外管环隙为250μm,温度为25℃的条件下,苯酚去除率可达99%以上.%The degradation of phenol in aqueous solution by ozone oxidation has been studied in a microporous tube-in-tube microchannel reactor (MTMCR). The results indicated that the removal percentage of phenol decreased with increasing micropore size, annular channel width and initial phenol concentration, and increased with increasing ratio of gas volumetric flow rate to liquid volumetric flow rate and reaction temperature. It was also observed that the removal percentage of phenol initially increased, and subsequently decreased with increasing pH value. A phenol removal percentage of over 99% was achieved under the following reaction conditions: initial phenol concentration of 100 mg/L, micropore size of 10μm, annular channel width of 250μm, ratio of gas volumetric flow rate to liquid volumetric flow rate of 13, pH value of 11 and reaction temperature of 25 ℃.

  13. Tailoring the Blast Exposure Conditions in the Shock Tube for Generating Pure, Primary Shock Waves: The End Plate Facilitates Elimination of Secondary Loading of the Specimen.

    Science.gov (United States)

    Kuriakose, Matthew; Skotak, Maciej; Misistia, Anthony; Kahali, Sudeepto; Sundaramurthy, Aravind; Chandra, Namas

    2016-01-01

    The end plate mounted at the mouth of the shock tube is a versatile and effective implement to control and mitigate the end effects. We have performed a series of measurements of incident shock wave velocities and overpressures followed by quantification of impulse values (integral of pressure in time domain) for four different end plate configurations (0.625, 2, 4 inches, and an open end). Shock wave characteristics were monitored by high response rate pressure sensors allocated in six positions along the length of 6 meters long 229 mm square cross section shock tube. Tests were performed at three shock wave intensities, which was controlled by varying the Mylar membrane thickness (0.02, 0.04 and 0.06 inch). The end reflector plate installed at the exit of the shock tube allows precise control over the intensity of reflected waves penetrating into the shock tube. At the optimized distance of the tube to end plate gap the secondary waves were entirely eliminated from the test section, which was confirmed by pressure sensor at T4 location. This is pronounced finding for implementation of pure primary blast wave animal model. These data also suggest only deep in the shock tube experimental conditions allow exposure to a single shock wave free of artifacts. Our results provide detailed insight into spatiotemporal dynamics of shock waves with Friedlander waveform generated using helium as a driver gas and propagating in the air inside medium sized tube. Diffusion of driver gas (helium) inside the shock tube was responsible for velocity increase of reflected shock waves. Numerical simulations combined with experimental data suggest the shock wave attenuation mechanism is simply the expansion of the internal pressure. In the absence of any other postulated shock wave decay mechanisms, which were not implemented in the model the agreement between theory and experimental data is excellent.

  14. Application of structural reliability to multi-circumferential cracking in steam generator tubes; Application de la fiabilite des structures a la multifissuration circonferentielle des tubes de generateur de vapeur

    Energy Technology Data Exchange (ETDEWEB)

    Ardillon, E.; Riffard, T. [Electricite de France (EDF), 78 - Chatou (France). Direction des Etudes et Recherches

    1997-12-31

    The COMPROMIS Code, developed by Electricite de France, is a probabilistic software tool concerned with assessment of probability of occurrence of a Steam Generator (SG) tube rupture caused by multi-circumferential cracking. It involves the calculation of low probabilities, for which Monte Carlo stratified sampling was selected. After a short description of the physical model, this paper presents the implementation of the numerical methods, some outputs of the code and sensitivity results of the rupture probability to input parameters. (author). 7 refs.

  15. GRUVAL for ET inspection of the steam generator tubes; GRUVAL para la inspeccion ET de los tubos de los Generadores de Vapor

    Energy Technology Data Exchange (ETDEWEB)

    Garcia Bueno, A.; Francia, L.; Jimenez Garcia, J. J.; Garcia, R.; Castelinou, M.; Torrens, J.

    2013-07-01

    The steam generators of the nuclear power plants, PWR type are one of the most important components from the point of view of safety and plant availability. Thousands of tubes that form, approximately 1 mm of thickness, required to be inspected in accordance with codes and standards, to ensure the integrity of the component during the operation of the plant.

  16. User-Generated Content, YouTube and Participatory Culture on the Web: Music Learning and Teaching in Two Contrasting Online Communities

    Science.gov (United States)

    Waldron, Janice

    2013-01-01

    In this paper, I draw on seminal literature from new media researchers to frame the broader implications that user-generated content (UGC), YouTube, and participatory culture have for music learning and teaching in online communities; to illustrate, I use examples from two contrasting online music communities, the Online Academy of Irish…

  17. Computational fluid dynamics (CFD) simulations of aerosol in a U-shaped steam generator tube

    Science.gov (United States)

    Longmire, Pamela

    scenario evaluated but ranged from 1.61 to 3.2. At the outlet, the computed AMMD (1.9 mum) had GSD between 1.12 and 2.76. Decontamination factors (DF), computed based on deposition from trajectory calculations, were just over 3.5 for the bend and 4.4 at the outlet. Computed DFs were consistent with expert elicitation cited in NUREG-1150 for aerosol retention in steam generators.

  18. The accelerator tube of ions of the generator Van de Graaff of the CEA. Survey of development. First results; Le tube accelerateur d'ions du generateur van de graapp du commissariat. Etude de developpement. Premiers resultats

    Energy Technology Data Exchange (ETDEWEB)

    Bruck, H.; Prevot, F. [Commissariat a l' Energie Atomique, Saclay(France). Centre d' Etudes Nucleaires

    1953-07-01

    Rare are the Van de Graaff supplies whose tube doesn't collapse electrically to tensions and currents very lower to those that the generator can provide. We chose the general measurements: length and diameter, and put the accent on the survey of the individual element, so much to the mechanical viewpoint (installation, solidity, tightness and degassing), that to the electric viewpoint (to increase the electric rigidity of it). After modification the breakdown voltage as well as the performances of the tube have been improved greatly. (M.B.) [French] Rares sont les machines de Van de Graaff dont le tube ne s'effondre pas electriquement a des tensions et des courants bien inferieurs a ceux que le generateur peut fournir. Nous avons choisi les dimensions generales: longueur et diametre, et mis l'accent sur l'etude de l'element individuel, tant au point de vue mecanique (montage, solidite, etancheite et degazage), qu'au point de vue electrique (pour en augmenter la rigidite electrique). Apres modification la tension de claquage ainsi que les performances du tube ont ete grandement ameliorees. (M.B.)

  19. The effect of shape of winglet vortex generator on the thermal-hydrodynamic performance of a circular tube bank fin heat exchanger

    Science.gov (United States)

    Hu, Wanling; Wang, Liangbi; Guan, Yong; Hu, Wenju

    2017-09-01

    In real application, the shape of the vortex generator has great influence on the heat transfer and flow resistance characteristics of tube bank fin heat exchanger. Therefore, the effect of the shape of the vortex generator on heat transfer performance of such heat exchanger should be considered. In this paper, the effect of three different shaped vortex generators (i.e. delta winglet, rectangular winglet and trapezoid winglet) on heat transfer intensity and secondary flow intensity of a circular tube bank fin heat exchanger was numerically studied. The results show that with increasing Re, overall average Nu and the non-dimensional secondary flow intensity Se m increase however friction factor f decreases. A corresponding relationship can be found between Nu and Se m, which indicates that the secondary flow intensity determines the heat transfer intensity in the fin-side channel of circular tube bank fin heat exchanger with different shaped vortex generators on the fin surfaces. Under the identical pumping power constrain, the optimal shape of the vortex generators is the delta winglet vortex generators for the studied cases.

  20. "People power" or "pester power"? YouTube as a forum for the generation of evidence and patient advocacy.

    Science.gov (United States)

    Mazanderani, Fadhila; O'Neill, Braden; Powell, John

    2013-12-01

    Venoplasty has been proposed, alongside the theory of chronic cerebrospinal venous insufficiency (CCSVI), as a treatment for multiple sclerosis (MS). Despite concerns about its efficacy and safety, thousands of patients have undergone the procedure. This paper analyses YouTube videos where patients have shared their treatment experiences. Content analysis on the 100 most viewed videos from over 4000 identified in a search for 'CCSVI', and qualitative thematic analysis on popular 'channels' demonstrating patients' experiences. Videos adopt an overwhelmingly positive stance towards CCSVI; many were uploaded by patients and present pre- and/or post-treatment experiences. Patients demonstrate rather than merely describe their symptoms, performing tests on themselves before and after treatment to quantify improvement. Videos combine medical terminology and tests with personal experiences of living with MS. Social media technologies provide patients with novel opportunities for advocating for particular treatments; generating alternative forms of 'evidence' built on a hybrid of personal experience and medical knowledge. Healthcare practitioners need to engage with new digital forms of content, including online social media. Instead of disregarding sources not considered 'evidence-based', practitioners should enhance their understanding of what 'experiential-evidence' is deemed significant to patients, particularly in contested areas of healthcare. Copyright © 2013 The Authors. Published by Elsevier Ireland Ltd.. All rights reserved.

  1. Liquid metal reactor KALIMER development - Study on the high temperature properties of the steam generator tubing for LMFBR

    Energy Technology Data Exchange (ETDEWEB)

    Park, Yong Soo; Kim, Soon Tae; Park, Hui Sang; Kim, Soo Han [Yonsei University, Seoul (Korea); Kim, Young Sik [Andong National University, Andong (Korea)

    1999-04-01

    This work dealt with the evaluation of super stainless steels for steam generator tubing of LMFBR. The experimental alloys were designed to simulate the elimination of alloying elements, in special, C and N. Regardless of carbon contents, super stainless steels showed the excellent properties (tensile properties and corrosion resistance) than those of 9Cr-1Mo steel. Nitrogen content has affected positively the ultimate tensile strength and yield strength by TT(Thermal Treatment), but the elongation was reduced by TT in case of nitrogen free alloy and the elongation was largely increased by TT in case of nitrogen bearing alloys. In acidic chloride environment, nitrogen has influenced a little on corrosion potential and critical current density, but largely on passive current density, especially, at high potential. However, the trend of corrosion potential and critical current density by nitrogen was similar to the results in acidic solutions, but passive current density was largely affected by nitrogen content of stainless steels. 29 refs., 24 figs., 8 tabs. (Author)

  2. Application of dynamic probabilistic safety assessment approach for accident sequence precursor analysis: Case study for steam generator tube rupture

    Energy Technology Data Exchange (ETDEWEB)

    Lee, Han Sul; Heo, Gyun Young [Kyung Hee University, Yongin (Korea, Republic of); Kim, Tae Wan [Incheon National University, Incheon (Korea, Republic of)

    2017-03-15

    The purpose of this research is to introduce the technical standard of accident sequence precursor (ASP) analysis, and to propose a case study using the dynamic-probabilistic safety assessment (D-PSA) approach. The D-PSA approach can aid in the determination of high-risk/low-frequency accident scenarios from all potential scenarios. It can also be used to investigate the dynamic interaction between the physical state and the actions of the operator in an accident situation for risk quantification. This approach lends significant potential for safety analysis. Furthermore, the D-PSA approach provides a more realistic risk assessment by minimizing assumptions used in the conventional PSA model so-called the static-PSA model, which are relatively static in comparison. We performed risk quantification of a steam generator tube rupture (SGTR) accident using the dynamic event tree (DET) methodology, which is the most widely used methodology in D-PSA. The risk quantification results of D-PSA and S-PSA are compared and evaluated. Suggestions and recommendations for using D-PSA are described in order to provide a technical perspective.

  3. In vitro degradation of human tropoelastin by MMP-12 and the generation of matrikines from domain 24.

    Science.gov (United States)

    Taddese, Samuel; Weiss, Anthony S; Jahreis, Günther; Neubert, Reinhard H H; Schmelzer, Christian E H

    2009-03-01

    Degradation of elastic fibers in tissues can result in the development of disorders that include aneurysms, atherosclerosis, and loss of skin elasticity. Tropoelastin is the precursor of the cross-linked elastin and its expression is triggered by elastin-degrading factors as a response to damage. Factors like UV radiation not only increase the expression of tropoelastin but also potent metalloelastases such as macrophage elastase (MMP-12). The development of elastin-degrading diseases, moreover, is a chronic process during which elastin and tropoelastin are repeatedly exposed to attacks by MMP-12. Hence, in this work we report the in vitro susceptibility of tropoelastin and the potential of MMP-12 to generate matrikines. This work provides evidence that tropoelastin is substantially and rapidly degraded by MMP-12 even at very dilute enzyme concentrations. MMP-12 cleaves at least 86 sites in tropoelastin. Analysis of the generated peptides revealed that some small peptides contained the motif GXXPG that may enable them to bind with the elastin binding protein (EBP). Furthermore, using synthesized peptides it was confirmed that several sites in the sequence encoded by exon 24 which contains repetitive units of biologically active VGVAPG domains are susceptible to attack by MMP-12, provided that the active subsites in MMP-12 (S(4) to S(4)') are occupied. Such cleavage events have lead to the generation of ligands that may bind to EBP.

  4. Next-generation sequencing for rodent barcoding: species identification from fresh, degraded and environmental samples.

    Science.gov (United States)

    Galan, Maxime; Pagès, Marie; Cosson, Jean-François

    2012-01-01

    Rodentia is the most diverse order among mammals, with more than 2,000 species currently described. Most of the time, species assignation is so difficult based on morphological data solely that identifying rodents at the specific level corresponds to a real challenge. In this study, we compared the applicability of 100 bp mini-barcodes from cytochrome b and cytochrome c oxidase 1 genes to enable rodent species identification. Based on GenBank sequence datasets of 115 rodent species, a 136 bp fragment of cytochrome b was selected as the most discriminatory mini-barcode, and rodent universal primers surrounding this fragment were designed. The efficacy of this new molecular tool was assessed on 946 samples including rodent tissues, feces, museum samples and feces/pellets from predators known to ingest rodents. Utilizing next-generation sequencing technologies able to sequence mixes of DNA, 1,140 amplicons were tagged, multiplexed and sequenced together in one single 454 GS-FLX run. Our method was initially validated on a reference sample set including 265 clearly identified rodent tissues, corresponding to 103 different species. Following validation, 85.6% of 555 rodent samples from Europe, Asia and Africa whose species identity was unknown were able to be identified using the BLASTN program and GenBank reference sequences. In addition, our method proved effective even on degraded rodent DNA samples: 91.8% and 75.9% of samples from feces and museum specimens respectively were correctly identified. Finally, we succeeded in determining the diet of 66.7% of the investigated carnivores from their feces and 81.8% of owls from their pellets. Non-rodent species were also identified, suggesting that our method is sensitive enough to investigate complete predator diets. This study demonstrates how this molecular identification method combined with high-throughput sequencing can open new realms of possibilities in achieving fast, accurate and inexpensive species identification.

  5. Numerical investigation for finding the appropriate design parameters of a fin-and-tube heat exchanger with delta-winglet vortex generators

    Science.gov (United States)

    Behfard, M.; Sohankar, A.

    2016-01-01

    A numerical simulation is performed to investigate the heat transfer and pressure drop characteristics of three-row inline tube bundles as a part of a heat exchanger (Re = 1000, Pr = 4.29). To enhance heat transfer, two pairs of delta winglet-type vortex generators (VGs) installed beside the first row and between the first and second rows of the tube bundles. The diameter of the second row of the tubes is chosen smaller than those of the first and third. A comprehensive study on the effects of various geometrical parameters such as transverse and longitudinal positions of VGs, length and height of VGs and angle of attack of the delta winglets is performed to augment heat transfer. Based on this study the best values of these design parameters are determined. The results showed that the best model increases the convective heat transfer ratio and thermal performance factor about 59 and 43 %, respectively, in compare with the geometry without VG.

  6. Ear Tubes

    Science.gov (United States)

    ... ENTCareers Marketplace Find an ENT Doctor Near You Ear Tubes Ear Tubes Patient Health Information News media ... and throat specialist) may be considered. What are ear tubes? Ear tubes are tiny cylinders placed through ...

  7. On-line electrochemically controlled in-tube solid phase microextraction of inorganic selenium followed by hydride generation atomic absorption spectrometry

    Energy Technology Data Exchange (ETDEWEB)

    Asiabi, Hamid [Department of Chemistry, Tarbiat Modares University, P.O. Box 14115-175, Tehran (Iran, Islamic Republic of); Yamini, Yadollah, E-mail: yyamini@modares.ac.ir [Department of Chemistry, Tarbiat Modares University, P.O. Box 14115-175, Tehran (Iran, Islamic Republic of); Seidi, Shahram [Department of Analytical Chemistry, Faculty of Chemistry, K.N. Toosi University of Technology, Tehran (Iran, Islamic Republic of); Shamsayei, Maryam; Safari, Meysam; Rezaei, Fatemeh [Department of Chemistry, Tarbiat Modares University, P.O. Box 14115-175, Tehran (Iran, Islamic Republic of)

    2016-05-30

    In this work, for the first time, a rapid, simple and sensitive microextraction procedure is demonstrated for the matrix separation, preconcentration and determination of inorganic selenium species in water samples using an electrochemically controlled in-tube solid phase microextraction (EC-in-tube SPME) followed by hydride generation atomic absorption spectrometry (HG-AAS). In this approach, in which EC-in-tube SPME and HG-AAS system were combined, the total analysis time, was decreased and the accuracy, repeatability and sensitivity were increased. In addition, to increases extraction efficiency, a novel nanostructured composite coating consisting of polypyrrole (PPy) doped with ethyleneglycol dimethacrylate (EGDMA) was prepared on the inner surface of a stainless-steel tube by a facile electrodeposition method. To evaluate the offered setup and the new PPy-EGDMA coating, it was used to extract inorganic selenium species in water samples. Extraction of inorganic selenium species was carried out by applying a positive potential through the inner surface of coated in-tube under flow conditions. Under the optimized conditions, selenium was detected in amounts as small as 4.0 parts per trillion. The method showed good linearity in the range of 0.012–200 ng mL{sup −1}, with coefficients of determination better than 0.9996. The intra- and inter-assay precisions (RSD%, n = 5) were in the range of 2.0–2.5% and 2.7–3.2%, respectively. The validated method was successfully applied for the analysis of inorganic selenium species in some water samples and satisfactory results were obtained. - Graphical abstract: An electrochemically controlled in-tube solid phase microextraction followed by hydride generation atomic absorption spectrometry was developed for extraction and determination ultra-trace amounts of Se in aqueous solutions. - Highlights: • A nanostructured composite coating consisting of PPy doped with EGDMA was prepared. • The coating was

  8. Degradation behavior of Ni3Al plasma-sprayed boiler tube steels in an energy generation system

    Science.gov (United States)

    Sidhu, Buta Singh; Prakash, S.

    2005-06-01

    Boiler steels, namely, low-C steel, ASTM-SA210-Grade A1 (GrA1), 1Cr-0.5Mo steel, ASTM-SA213-T-11 (T11) and 2.25Cr-1Mo steel, ASTM-SA213-T-22 (T22) were plasma sprayed with Ni3Al. The alloy powder was prepared by mixing Ni and Al in the stoichiometric ratio of 3 to 1. The Ni-22Cr-10Al-1Y alloy powder was used as a bond coat, with a 150 µm thick layer sprayed onto the surface before applying the 200 µm coating of Ni3Al. Exposure studies have been performed in the platen superheater zone of a coal-fired boiler at around 755 °C for 10 cycles, each of 100 h duration. The protection to the base steel was minimal for the three steels. Scale spallation and the formation of a porous and nonadherent NiO scale were probably the main reasons for the lack of protection. In the case of T22-coated steel, cracks in the coatings have been observed after the first 100 h exposure cycle.

  9. Degradation behavior of Ni{sub 3}Al plasma-sprayed boiler tube steels in an energy generation system

    Energy Technology Data Exchange (ETDEWEB)

    Sidhu, B.S.; Prakash, S. [GZS, Bathinda (India). College of Engineering

    2005-06-01

    Boiler steels, namely, low-C steel, ASTM-SA210-Grade A1 (GrA1), 1Cr-0.5Mo steel, ASTM-SA213-T-11 (T11) and 2.25Cr-1Mo steel, ASTM-SA213-T-22 (T22) were plasma sprayed with Ni3Al. The alloy powder was prepared by mixing Ni and Al in the stoichiometric ratio of 3 to 1. The Ni-22Cr-10Al-1Y alloy powder was used as a bond coat, with a 150{mu} m thick layer sprayed onto the surface before applying the 200{mu}m coating of Ni{sub 3}Al. Exposure studies have been performed in the platen superheater zone of a coal-fired boiler at around 755{sup o}C for 10 cycles, each of 100 h duration. The protection to the base steel was minimal for the three steels. Scale spallation and the formation of a porous and nonadherent NiO scale were probably the main reasons for the lack of protection. In the case of T22-coated steel, cracks in the coatings have been observed after the first 100 h exposure cycle.

  10. [Extraction, Purification and Identification of a Dexamethasone-degrading Enzymes Generated by Pseudomonas Alcaligenes].

    Science.gov (United States)

    Zhu, Lili; Yang, Zhibang; Yang, Qian; Shi, Zhongquan; Deng, Xichuan

    2015-10-01

    In this research a strain of isolated Pseudomonas alcaligenes which causes degradation of dexamethasone was acclimated further and its proteins of every position in the bacterium were separated by the osmotic shock method. The separated intracellular proteins which had the highest enzyme activity were extracted by the salting out with ammonium sulfate and were purified with the cation exchange chromatography and gel chromatography. The purified proteins which was active to cause degradation of dexamethasone had been detected were cut with enzyme and were analyzed with mass spectrometry. The results showed that the degradation rate to dexamethasone by acclimated Pseudomonas alcaligenes were increased from 23.63% to 52.84%. The degrading enzymes were located mainly in the intracellular of the bacteria and its molecular weight was about 41 kD. The specific activity of the purified degrading enzymes were achieved to 1.02 U x mg(-1). Its 5-peptide amino acid sequences were consistent with some sequences of the isovaleryl-CoA dehydrogenase. The protein enzyme may be a new kind degrading enzyme of steroidal compounds. Our experimental results provided new strategies for cleanup of dexamethasone in water environment with microbial bioremediation technique.

  11. Flow topology, heat transfer characteristic and thermal performance in a circular tube heat exchanger inserted with punched delta winglet vortex generators

    Energy Technology Data Exchange (ETDEWEB)

    Boonloi, Amnart [College of Industrial Technology, Bangkok (Thailand); Jedsadaratanachai, Withada [Faculty of Engineering, Bangkok (Thailand)

    2016-01-15

    To improve the heat transfer rate and thermal performance, the punched delta winglet vortex generators, DWVGs, were inserted in the middle of the circular tube heat exchanger. The effects of the flow attack angles and the flow directions were investigated numerically for the Reynolds number Re = 100 – 2000. The finite volume method and the SIMPLE algorithm were used to study. The results are reported in terms of the flow structure, heat transfer behavior and thermal performance evaluation and also compared with the smooth tube with no vortex generators. As the numerical results, the use of the DWVGs in the tube can improve the heat transfer rate and thermal performance by creating the vortex flow through the tested section. The rise of the flow attack angle results in the increasing strength of the vortex flows. The flow attack angle of 25 .deg. performs the highest heat transfer rate and thermal performance, while the flow attack angle of 0 .deg. gives the reversed results. The computational results reveal that the optimum thermal enhancement factor is around 2.80 at Re = 2000, α = 25 .deg., with the winglet tip pointing downstream. The correlations on both the Nusselt number ratio and friction factor ratio for the DWVG in the tube heat exchanger are presented.

  12. Development of an Integrity Assessment Procedure for CANDU Pressure Tubes

    Energy Technology Data Exchange (ETDEWEB)

    Chung, Han Sub [Korea Electric Power Research Institute, Daejeon (Korea, Republic of)

    2010-10-15

    The pressure tubes used in a CANDU reactor are made from Zr-2.5Nb. During service the pressure tubes operate at temperatures between about 150 and 310 .deg. C, and with variable coolant pressures up to 11MPa corresponding to hoop stress of up to 130MPa. The maximum flux of fast neutrons (E>1MeV) from the fuel is about 4X10{sup 17}nm{sup -2}{sub s}{sup -1}. The pressure tubes are exposed to very severe degradation environment. The aging degradation of the pressure tubes are summarized as below. - Geometric deformation; axial elongation, diametric creep, and wall thinning. - Deuterium uptake; some fraction of the deuterium generated by the corrosion of pressure tubes is absorbed into the pressure tubes. Total equivalent hydrogen content in the pressure tube is the sum of the initial hydrogen content before operation and the deuterium uptake during operation. High concentration of hydrogen inside the pressure tubes makes the metal susceptible to Delayed Hydride Cracking. The DHC is a degradation mechanism of prime importance for CANDU pressure tubes. Mechanical properties, in particular fracture toughness, are deteriorated by high concentration of dissolved hydrogen. - Flaws; volumetric flaws are generated during operation. Wear scars by debris fretting, and bearing pad fretting are common. These volumetric flaws can be a site of crack initiation by fatigue or DHC. Cracks can propagate by DHC or fatigue crack propagation if conditions are met. - Material properties degradation; mechanical properties are affected by neutron irradiation. Yield strength and tensile strength are increased, and fracture toughness is deteriorated. The susceptibility to DHC is also affected. The integrity assessment of the pressure tube is a procedure to determine if the risk of pressure tube failure is controlled to maintain acceptably low. CSA N285.4 and 285.8 are two important guidelines regarding the integrity of pressure tubes. N285.4 is to guide in-service inspection, and N285

  13. Dry powder aerosols generated by standardized entrainment tubes from drug blends with lactose monohydrate: 1. Albuterol sulfate and disodium cromoglycate.

    Science.gov (United States)

    Xu, Zhen; Mansour, Heidi M; Mulder, Tako; McLean, Richard; Langridge, John; Hickey, Anthony J

    2010-08-01

    The major objective of this study was: discriminatory assessment of dry powder aerosol performance using standardized entrainment tubes (SETs) and lactose-based formulations with two model drugs. Drug/lactose interactive physical mixtures (2%w/w) were prepared. Their properties were measured: solid-state characterization of phase behavior and molecular interactions by differential scanning calorimetry and X-ray powder diffraction; particle morphology and size by scanning electron microscopy and laser diffraction; aerosol generation by SETs and characterization by twin-stage liquid impinger and Andersen cascade impactor operated at 60 L/min. The fine particle fraction (FPF) was correlated with SET shear stress (tau(s)), using a novel powder aerosol deaggregation equation (PADE). Drug particles were <5 microm in volume diameter with narrow unimodal distribution (Span <1). The lowest shear SET (tau(s) = 0.624 N/m(2)) gave a higher emitted dose (ED approximately 84-93%) and lower FPF (FPF(6.4) approximately 7-25%). In contrast, the highest shear SET (tau(s) = 13.143 N/m(2)) gave a lower ED (ED approximately 75-89%) and higher FPF (FPF(6.4) approximately 15-46%). The performance of disodium cromoglycate was superior to albuterol sulfate at given tau(s), as was milled with respect to sieved lactose monohydrate. Excellent correlation was observed (R(2) approximately 0.9804-0.9998) when pulmonary drug particle release from the surface of lactose carriers was interpreted by PADE linear regression for dry powder formulation evaluation and performance prediction.

  14. Statistical analysis of entropy generation in longitudinally finned tube heat exchanger with shell side nanofluid by a single phase approach

    OpenAIRE

    Konchada Pavan Kumar; Pv Vinay; Bhemuni Varaprasad

    2016-01-01

    The presence of nanoparticles in heat exchangers ascertained increment in heat transfer. The present work focuses on heat transfer in a longitudinal finned tube heat exchanger. Experimentation is done on longitudinal finned tube heat exchanger with pure water as working fluid and the outcome is compared numerically using computational fluid dynamics (CFD) package based on finite volume method for different flow rates. Further 0.8% volume fraction of aluminum oxide (Al2O3) nanofluid is conside...

  15. [Infrared Spectrum Studies of Hydrocarbon Generation and Structure Evolution of Peat Samples During Pyrolysis and Microbial Degradation].

    Science.gov (United States)

    Bao, Yuan; Ju, Yi-wen; Wei, Chong-tao; Wang, Chao-yong; Li, Xiao-shi

    2015-03-01

    Hydrocarbon generation and structural evolution would be occurred in the process of from coal-forming material (i. e. peat sample) transforming to the coal. While Fourier Transform Infrared Spectroscopy (FTIR) have a special advantages in analyzing molecular structure of samples. For understanding the characteristics of hydrocarbon generation and structural evolution of coal-forming material during the process of pyrolysis and microbial degradation, based on the physical simulation experiments of closed pyrolysis and anaerobic microbial degradation, the generation potential of thermogenic gas and biogenic gas were studied in this paper, and characteristics of molecular structure evolution and its mechanism was analyzed by FTIR technology. Results show that cumulative gas yields of hydrocarbon gases (mainly for methane) increased with experiment temperature. The gas yield of non-hydrocarbon gas (mainly for CO2) exhibited two peaks at 250 and 375 degrees C. The degradation ability of anaerobe on coal samples weakened with the maturity increasing and there was no gas generation on the pyrolysis samples with maturity from 1.6% to 1.8%. After pyrolysis, the content of hydroxyl in peat sample decreased first and then increased with the pyrolysis temperature increasing. The content of aldehyde carbonyl, methylene and phosphate reduced. The content of aromatic esters decreased with nonlinear. The bone of S-O in stretching vibration appeared after 350 degrees C and its content increased with temperature. This shows that the sulfocompound restrains the activity of methanogenic bacteria. After degradation by anaerobe, the relative content of hydroxyl, aldehyde carbonyl, aromatic esters, methylene and phosphate in peat sample dropped significantly. It is shown that the intermolecular force between these groups weakened.

  16. TRAC PF1/MOD1 calculations and data comparisons for mist feed and bleed and steam generator tube rupture experiments

    Energy Technology Data Exchange (ETDEWEB)

    Siebe, D.A.; Boyack, B.E.; Steiner, J.L.

    1988-01-01

    Los Alamos National Laboratory is a participant in the Integral System Test (IST) program initiated in June 1983 for the purpose of providing integral system test data on specific issues/phenomena relevant to post-small-break loss-of-coolant accidents, loss of feedwater and other transients in Babcock and Wilcox (BandW) plant designs. The Multi-Loop Integral System Test (MIST) facility is the largest single component in the IST program. MIST is a 2 /times/ 4 (two hot legs and steam generators (SGs), four cold legs and reactor coolant pumps) representation of lowered-loop reactor system of the BandW design. It is a full-height, full-pressure facility with 1/817 power and volume scaling. Two other integral experimental facilities are included in the IST program: test loops at the University of Maryland, College Park, and at SRI International (SRI-2). The objective of the IST tests is to generate high-quality experimental data to be used for assessing thermal-hydraulic safety computer codes. Efforts are under way at Los Alamos to assess TRAC-PF1/MOD1 against data from each of the IST facilities. Calculations and data comparisons for TRAC-PF1/MOD1 assessment are presented for two transients run in the MIST facility. These are MIST Test 330302, a feed and bleed test with delayed high-pressure injection; and Test 3404AA, an SG tube-rupture test with the affected SG isolated. Only MIST assessment results are presented in this paper. The TRAC-PF1/MOD1 calculations completed to date for MIST tests are in reasonable agreement with the data from these tests. Reasonable agreement is defined as meaning that major trends are predicted correctly, although TRAC values are frequently outside the range of data uncertainty. We believe that correct conclusions will be reached if the code is used in similar applications despite minor code/model deficiencies. 7 refs., 5 figs., 2 tabs.

  17. Generation of dried tube specimen for HIV-1 viral load proficiency test panels: a cost-effective alternative for external quality assessment programs.

    Science.gov (United States)

    Ramos, Artur; Nguyen, Shon; Garcia, Albert; Subbarao, Shambavi; Nkengasong, John N; Ellenberger, Dennis

    2013-03-01

    Participation in external quality assessment programs is critical to ensure quality clinical laboratory testing. Commercially available proficiency test panels for HIV-1 virus load testing that are used commonly in external quality assessment programs remain a financial obstacle to resource-limited countries. Maintaining cold-chain transportation largely contributes to the cost of traditional liquid proficiency test panels. Therefore, we developed and evaluated a proficiency test panel using dried tube specimens that can be shipped and stored at ambient temperature. This dried tube specimens panel consisted of 20 μl aliquots of a HIV-1 stock that were added to 2 ml tubes and left uncapped for drying, as a preservation method. The stability of dried tube specimens at concentrations ranging from 10² to 10⁶·⁵ RNA copies/ml was tested at different temperatures over time, showing no viral load reduction at 37 °C and a decrease in viral load smaller than 0.5 Log₁₀ at 45 °C for up to eight weeks when compared to initial results. Eight cycles of freezing-thawing had no effect on the stability of the dried tube specimens. Comparable viral load results were observed when dried tube specimen panels were tested on Roche CAPTAQ, Abbott m2000, and Biomerieux easyMAG viral load systems. Preliminary test results of dried proficiency test panels shipped to four African countries at ambient temperature demonstrated a low inter assay variation (SD range: 0.29-0.41 Log₁₀ RNA copies/ml). These results indicated that HIV-1 proficiency test panels generated by this methodology might be an acceptable alternative for laboratories in resource-limited countries to participate in external quality assessment programs.

  18. Characteristics of Spherical Shock Wave and Circular Pulse Jet Generated by Discharge of Propagating Shock Wave at Open End of Tube

    Institute of Scientific and Technical Information of China (English)

    Tsukasa Irie; Tsuyoshi Yasunobu; Hideo Kashimura; Toshiaki Setoguchi; Kazuyasu Matsuo

    2003-01-01

    When the shock wave propagating in the straight circular tube reaches at the open end, the impulsive wave is generated by the emission of a shock wave from an open end, and unsteady pulse jet is formed near the open end behind the impulsive wave under the specific condition. The pulse jet transits to spherical shock wave with the increase in the strength of shock wave. The strength is dependent on the Mach number of shock wave, which attenuates by propagation distance from the open end. In this study, the mechanism of generating the unsteady pulse jet, the characteristics of the pressure distribution in the flow field and the emission of shock wave from straight circular tube which has the infinite flange at open end are analyzed numerically by the TVD method. Strength of spherical shock wave, relation of shock wave Mach number, distance decay of spherical shock wave and directional characteristics are clarified.

  19. Repair boundary for parent tube indications within the upper joint zone of hybrid expansion joint (HEJ) sleeved tubes

    Energy Technology Data Exchange (ETDEWEB)

    Cullen, W.K.; Keating, R.F. [Westinghouse Electric, Pittsburgh, PA (United States)

    1997-02-01

    In the Spring and Fall of 1994, and the Spring of 1995, crack-like indications were found in the upper hybrid expansion joint (HEJ) region of Steam Generator (S/G) tubes which had been sleeved using Westinghouse HEJ sleeves. As a result of these findings, analytic and test evaluations were performed to assess the effect of the degradation on the structural, and leakage, integrity of the sleeve/tube joint relative to the requirements of the United States Nuclear Regulatory Commission`s (NRC) draft Regulatory Guide (RG) 1.121. The results of these evaluations demonstrated that tubes with implied or known crack-like circumferential parent tube indications (PTIs) located 1.1 inches or farther below the bottom of the hardroll upper transition, have sufficient, and significant, integrity relative to the requirements of RG 1.121. Thus, the purpose of this report is to provide background information related to the justification of the modified tube repair boundary.

  20. Computation of a leakage in a stream generator heating tube with realistic initial and boundary conditions; Berechnung eines Dampferzeugerheizrohrlecks mit realistischen Anfangs- und Randbedingungen

    Energy Technology Data Exchange (ETDEWEB)

    Sarkadi, Peter; Schaffrath, Andreas [TUeV NORD SysTec GmbH und Co. KG, Hamburg (Germany)

    2009-07-01

    In the frame of a PWR reactor safety analysis the TUEV Nord Sys Tec GmbH has analyzed the plant behavior in case of a steam generator tube leakage using the thermal hydraulic code ATHLET and realistic initial and boundary conditions. The aim of the analysis was to show that the response of the emergency cooling criteria including the activation of safety injection pumps can be avoided. The Activation of the safety injection pumps could jeopardize the activity retention.

  1. Creating a YouTube-Like Collaborative Environment in Mathematics: Integrating Animated GeoGebra Constructions and Student-Generated Screencast Videos

    Directory of Open Access Journals (Sweden)

    Geoffrey ROULET

    2013-01-01

    Full Text Available This article discusses the integration of student-generated GeoGebra applets and Jing screencast videos to create a YouTube-like medium for sharing in mathematics. The value of combining dynamic mathematics software and screencast videos for facilitating communication and representations in a digital era is demonstrated herein. We share our experience with using these tools to facilitate mathematical collaboration, focusing specifically on the power of GeoGebra for student expression and creativity

  2. Automated tube voltage selection for radiation dose and contrast medium reduction at coronary CT angiography using 3{sup rd} generation dual-source CT

    Energy Technology Data Exchange (ETDEWEB)

    Mangold, Stefanie [Medical University of South Carolina, Division of Cardiovascular Imaging, Department of Radiology and Radiological Science, Charleston, SC (United States); Eberhard-Karls University Tuebingen, Department of Diagnostic and Interventional Radiology, Tuebingen (Germany); Wichmann, Julian L. [Medical University of South Carolina, Division of Cardiovascular Imaging, Department of Radiology and Radiological Science, Charleston, SC (United States); University Hospital Frankfurt, Department of Diagnostic and Interventional Radiology, Frankfurt (Germany); Schoepf, U.J. [Medical University of South Carolina, Division of Cardiovascular Imaging, Department of Radiology and Radiological Science, Charleston, SC (United States); Medical University of South Carolina, Division of Cardiology, Department of Medicine, Charleston, SC (United States); Poole, Zachary B.; Varga-Szemes, Akos; De Cecco, Carlo N. [Medical University of South Carolina, Division of Cardiovascular Imaging, Department of Radiology and Radiological Science, Charleston, SC (United States); Canstein, Christian [Siemens Medical Solutions, Malvern, PA (United States); Caruso, Damiano [Medical University of South Carolina, Division of Cardiovascular Imaging, Department of Radiology and Radiological Science, Charleston, SC (United States); University of Rome ' ' Sapienza' ' , Department of Radiological Sciences, Oncology and Pathology, Rome (Italy); Bamberg, Fabian; Nikolaou, Konstantin [Eberhard-Karls University Tuebingen, Department of Diagnostic and Interventional Radiology, Tuebingen (Germany)

    2016-10-15

    To investigate the relationship between automated tube voltage selection (ATVS) and body mass index (BMI) and its effect on image quality and radiation dose of coronary CT angiography (CCTA). We evaluated 272 patients who underwent CCTA with 3{sup rd} generation dual-source CT (DSCT). Prospectively ECG-triggered spiral acquisition was performed with automated tube current selection and advanced iterative reconstruction. Tube voltages were selected by ATVS (70-120 kV). BMI, effective dose (ED), and vascular attenuation in the coronary arteries were recorded. Signal-to-noise ratio (SNR) and contrast-to-noise ratio (CNR) were calculated. Five-point scales were used for subjective image quality analysis. Image quality was rated good to excellent in 98.9 % of examinations without significant differences for proximal and distal attenuation (all p ≥.0516), whereas image noise was rated significantly higher at 70 kV compared to ≥100 kV (all p <.0266). However, no significant differences were observed in SNR or CNR at 70-120 kV (all p ≥.0829). Mean ED at 70-120 kV was 1.5 ± 1.2 mSv, 2.4 ± 1.5 mSv, 3.6 ± 2.7 mSv, 5.9 ± 4.0 mSv, 7.9 ± 4.2 mSv, and 10.7 ± 4.1 mSv, respectively (all p ≤.0414). Correlation analysis showed a moderate association between tube voltage and BMI (r =.639). ATVS allows individual tube voltage adaptation for CCTA performed with 3{sup rd} generation DSCT, resulting in significantly decreased radiation exposure while maintaining image quality. (orig.)

  3. Phenomenological modeling of eddy current signals with a view to characterizing steam generator tube flaws; Modelisation phenomenologique des signaux courants de Foucault en vue de la caracterisation des defauts des tubes de generateurs de vapeur

    Energy Technology Data Exchange (ETDEWEB)

    La, R

    1997-12-31

    This work deals with the eddy current non-destructive test ing. Its long-term goal is to design an `inverse model` for evaluating the geometry an d the dimensions of steam generator tube flaws from eddy current signals. The approach we adopted requires the preliminary knowledge of a `forward model` that estimates the eddy current signal knowing the geometry and the dimensions of the flaws. A quasi-exhaustive study of the existing forward models showed their inadequacy to solve the inverse problem. Hence, we proposed to build a general forward model, appropriate to the inversion. Using a parametric approach, this model is phenomenological, i.e. it is based on observations made from results of a finite element code. For each position of the coil, the proposed forward model fist discretized the eddy current distribution into `tubes of current`. A parametric description of the shape of these tubes is given according the system constituted of the coil and the tubes of current as a `multi-transformer`, their current signal, can then be deduced. The model was validated in the case of an axisymmetric configuration. Comparisons with both analytical and numerical models showed very good agreements. Then, the proposed model was applied to a three-dimensional configuration. Comparisons with experimental results are sufficiently conclusive to validate the approach to the construction of the phenomenological model. However, before envisaging the inverse problem, the computation time, still too long, ought to be reduced and the parametric description needs to be generalized to other three-dimensional configurations. (author). 92 refs.

  4. Photoelectrocatalytic hydrogen generation and simultaneous degradation of organic pollutant via CdSe/TiO{sub 2} nanotube arrays

    Energy Technology Data Exchange (ETDEWEB)

    Wang, Wenchao [Department of Chemistry, Key Laboratory of Resource Chemistry of Ministry of Education, Shanghai Normal University, Shanghai 200234 (China); Li, Fang [Department of Chemistry, Key Laboratory of Resource Chemistry of Ministry of Education, Shanghai Normal University, Shanghai 200234 (China); Department of Mechanical Engineering, The University of Hong Kong, Pok Fu Lam, Hong Kong (China); Zhang, Dieqing [Department of Chemistry, Key Laboratory of Resource Chemistry of Ministry of Education, Shanghai Normal University, Shanghai 200234 (China); Leung, Dennis Y.C., E-mail: ycleung@hku.hk [Department of Mechanical Engineering, The University of Hong Kong, Pok Fu Lam, Hong Kong (China); Li, Guisheng, E-mail: liguisheng@shnu.edu.cn [Department of Chemistry, Key Laboratory of Resource Chemistry of Ministry of Education, Shanghai Normal University, Shanghai 200234 (China)

    2016-01-30

    Graphical abstract: A highly efficient CdSe/TiO{sub 2} nanotube arrays photoanode was explored via the electrodeposition with ion-exchange method for photoelectrocatalytic hydrogen evolution and simultaneous degradation of organic pollutant under visible light irradiation. - Highlights: • CdSe nanoparticles enhanced TiO{sub 2} nanotube arrays electrode was prepared by an electrodeposition with ion-exchange method. • CdSe nanoparticles were strongly bonded on the pore walls of TiO{sub 2} nanotube arrays, with the formation of CdSe–TiO{sub 2} heterojunctions. • Such CdSe/TiO{sub 2} nanotubes arrays, acting as photoanode, exhibited high efficiency for both generation of hydrogen and degradation of MO in photoelectrocatalysis reaction system under visible-light irradiation. - Abstract: CdSe nanoparticles enhanced TiO{sub 2} nanotube arrays electrodes (CdSe/TNTAs) were explored as the photoanode for driving the photoelectrocatalytic (PEC) generation of hydrogen and simultaneous degradation of organic pollutants in a PEC system. The evolution hydrogen and the simultaneous degradation of organic pollutants were performed in an electrolytic cell (three electrodes system) under visible-light (λ > 400 nm). Such CdSe/TiO{sub 2} based PEC system exhibited both high efficiency of hydrogen generation and effective oxidation of methyl orange (MO). Such high PEC performance of CdSe/TNTAs was attributed to the high dispersity of CdSe nanoparticles on both outside and inside of the pore walls of TiO{sub 2} nanotube arrays, the strong combination and heterojunctions between CdSe and TiO{sub 2} through Cd−O bonds via electrodeposition with ion-exchange method.

  5. Degradation of methyl and ethyl mercury by singlet oxygen generated from sea water exposed to sunlight or ultraviolet light.

    Science.gov (United States)

    Suda, I; Suda, M; Hirayama, K

    1993-01-01

    Photodegradation of methyl mercury (MeHg) and ethyl Hg (EtHg) in sea water was studied by sunlight or ultraviolet (UV) light exposure, and by determining inorganic Hg produced by degradation. Sea water containing 1 microM MeHg or EtHg was exposed to sunlight or UV light. N-Acetyl-L-cysteine was added to the solution for preventing Hg loss during the light exposure. MeHg and EtHg in sea water were degraded by sunlight (> 280 nm), UV light A (320-400 nm) and UV light B (280-320 nm), though the amounts of inorganic Hg produced from MeHg were 1/6th to 1/12th those from EtHg. Inorganic Hg production was greater with increasing concentration of sea water. Degradation of MeHg and EtHg by the UV light A exposure was inhibited by singlet oxygen (1O2) trappers such as NaN3, 1,4-diazabicyclo[2,2,2]octane, histidine, methionine and 2,5-dimethylfuran. On the other hand, inhibitors or scavengers of superoxide anion, hydrogen peroxide or hydroxyl radical did not inhibit the photodegradation of alkyl Hg. These results suggested that 1O2 generated from sea water exposed to sunlight, UV light A or UV light B was the reactive oxygen species mainly responsible for the degradation of MeHg and EtHg.

  6. Optimization of degradation of Reactive Black 5 (RB5) and electricity generation in solar photocatalytic fuel cell system.

    Science.gov (United States)

    Khalik, Wan Fadhilah; Ho, Li-Ngee; Ong, Soon-An; Voon, Chun-Hong; Wong, Yee-Shian; Yusoff, NikAthirah; Lee, Sin-Li; Yusuf, Sara Yasina

    2017-10-01

    The photocatalytic fuel cell (PFC) system was developed in order to study the effect of several operating parameters in degradation of Reactive Black 5 (RB5) and its electricity generation. Light irradiation, initial dye concentration, aeration, pH and cathode electrode are the operating parameters that might give contribution in the efficiency of PFC system. The degradation of RB5 depends on the presence of light irradiation and solar light gives better performance to degrade the azo dye. The azo dye with low initial concentration decolorizes faster compared to higher initial concentration and presence of aeration in PFC system would enhance its performance. Reactive Black 5 rapidly decreased at higher pH due to the higher amount of OH generated at higher pH and Pt-loaded carbon (Pt/C) was more suitable to be used as cathode in PFC system compared to Cu foil and Fe foil. The rapid decolorization of RB5 would increase their voltage output and in addition, it would also increase their Voc, Jsc and Pmax. The breakage of azo bond and aromatic rings was confirmed through UV-Vis spectrum and COD analysis. Copyright © 2017 Elsevier Ltd. All rights reserved.

  7. Efficiency and entropy generation in fined tube solar collectors systems; Eficiencia e geracao de entropia em sistemas de tubos aletados coletores de energia solar

    Energy Technology Data Exchange (ETDEWEB)

    Santos, Marcio Bueno dos [Instituto Nacional de Pesquisas Espaciais (INPE), Sao Jose dos Campos, SP (Brazil). Lab. de Integracao e Testes; Saboya, Sergio Mourao [Instituto Tecnologico de Aeronautica, Sao Jose dos Campos, SP (Brazil). Dept. de Energia

    1998-07-01

    This paper studies the efficiency of a fined tube solar collector used in artificial satellites and the relation of this efficiency with the entropy generation in the fin. The mathematical modeling of heat transfer in the collector leads to a non-linear integrodifferential system of equations, which is solved numerically. The solution gives the efficiency, which is presented as function of geometrical and physical characteristics of the collector. It is also shown that a minimum entropy generation in the fins, in a collector, whose characteristics are subjected to constraints, corresponds to an optimum efficiency, that is, an efficiency value advantageous to collector performance. (author)

  8. High-temperature degradation and protection of ferritic and austenitic steels in steam generators

    Science.gov (United States)

    Martínez-Villafañe, A.; Almeraya-Calderón, M. F.; Gaona-Tiburcio, C.; Gonzalez-Rodriguez, J. G.; Porcayo-Calderón, J.

    1998-02-01

    The useful life of superheaters and reheaters of power stations which use heavy fuel oil is shortened and their continuous service is inhibited by corrosion (fireside) and creep-type problems. The increase of corrosion attack on boilers is caused by the presence of fuel ash deposits containing mainly vanadium, sodium, and sulfur which form low-melting-point compounds. The tubes are exposed to the action of high stresses and high temperatures, producing the so-called “creep damage.” In this work, two kinds of results are reported: lab and field studies using a 2.25Cr-1Mo steel. The laboratory work was in turn divided into two parts. In the first, the steel was exposed to the action of natural ash deposits in oxidant atmospheres at 600 ° for 24 h. In the second part, tensile specimens were creep tested in Na2SO4, V2O5, and their mixture over a temperature range of 580 to 620 °. In the field work, components of a power station were coated with different types of nickel-and iron-base coatings containing chromium, Fe-Cr, and Fe-Si using the powder flame spraying technique. After testing, the coated tubes were analyzed using electron microscopy. The results showed that all the coating systems had good corrosion resistance, especially those containing silicon or chromium.

  9. In vitro degradation and total gas production of byproducts generated in the biodiesel production chain

    Directory of Open Access Journals (Sweden)

    Raissa Kiara oliveira de Morais

    2015-05-01

    Full Text Available This study aimed to evaluate the in vitro degradation and total gas production of different oil seed press cakes from a biodiesel production chain gas through the use of a semi-automatic technique of gas production in vitro. The treatments consisted of substituting elephant grass in increasing levels, 0%, 30, 50 and 70%, with the byproducts of Gossyypium hirsutum, Ricinus communis, Moringa oleifeira, Jatropha curcas and Helianthus annus. The oil seed press cakes of Moringa oleifeira had the highest rate of in vitro degradation of dry matter compared with other foods but did not result in a higher final volume of gases production. Gossyypium hirsutum, Pinhão manso curcas and Ricinus communis showed a higher in vitro degradability of similar dry matter. The highest total gas production was obtained by the oil seed press cakes of Helianthus annus. The oil seed press cakes of Moringa oleifeira can replace elephant grass up to 70% and therefore reduce both greenhouse gas emissions and energy loss for the animal.

  10. Debris generation from Mechanical degradation of MLI and thermo-control coating

    Science.gov (United States)

    Duzellier, Sophie; Drolshagen, Gerhard; Pons, Claude; Rey, Romain; Gordo, Paulo; Horstmann, Andre

    2016-07-01

    Space environment is a harsh environment for exposed materials. Amongst all environmental constraints, ionizing radiation in GEO (particles, UV), atomic oxygen in LEO and temperature variation through synergy mechanisms may lead to serious damage and loss of performance of surface materials (thermo-optical or mechanical properties). Optical and radar observations from the ground as well as analysis of retrieved hardware have shown an abundance of space debris objects that seem to result from the degradation of outer spacecraft surfaces. Recent surveys of the GEO and GTO region have found many objects with high area-to-mass ratio (HAMR debris, see T. Childknecht et al. 2003, 2004, 2005) indicating that they must consist of relatively thin material, like foils. This paper explores the cause, amount and characteristics of space debris objects resulting from spacecraft surface degradation in order to improve space debris population models and support the selection of materials in the context of debris mitigation measures. 20-year GEO dose profile along with thermal cycling has been applied to a set of MLI assemblies and painting samples. The material degradation was monitored through in and ex situ characterizations (visual observation, mechanical and thermo-optical). No self-flaking was observed for paintings nor for MLIs. However, paint surfaces became very brittle, whereas reclosable fasteners of MLIs and Mylar inner foils were strongly damaged as well. Potential scenarios for delamination of MLI foils could be defined.

  11. Phenomenological model of photoluminescence degradation and photoinduced defect formation in silicon nanocrystal ensembles under singlet oxygen generation

    Energy Technology Data Exchange (ETDEWEB)

    Gongalsky, Maxim B., E-mail: mgongalsky@gmail.com; Timoshenko, Victor Yu. [Faculty of Physics, Moscow State M.V. Lomonosov University, 119991 Moscow (Russian Federation)

    2014-12-28

    We propose a phenomenological model to explain photoluminescence degradation of silicon nanocrystals under singlet oxygen generation in gaseous and liquid systems. The model considers coupled rate equations, which take into account the exciton radiative recombination in silicon nanocrystals, photosensitization of singlet oxygen generation, defect formation on the surface of silicon nanocrystals as well as quenching processes for both excitons and singlet oxygen molecules. The model describes well the experimentally observed power law dependences of the photoluminescence intensity, singlet oxygen concentration, and lifetime versus photoexcitation time. The defect concentration in silicon nanocrystals increases by power law with a fractional exponent, which depends on the singlet oxygen concentration and ambient conditions. The obtained results are discussed in a view of optimization of the photosensitized singlet oxygen generation for biomedical applications.

  12. Constitution of Drop-Tube-Generated Coal Chars from Vitrinite- and Inertinite-Rich South African Coals

    Energy Technology Data Exchange (ETDEWEB)

    Louw, Enette B.; Mitchell, Gareth D.; Wang, Juan; Winans, Randall E.; Mathews, Jonathan P.

    2016-01-21

    The structural transformations of coal and the resultant char morphologies are strongly dependent on the initial structure and degree of thermoplasticity achieved during coal-to-char transition. These are a function of petrographic composition, rank, particle size, and heating rate and strongly affect combustion behavior. This study compares the devolatilization and subsequent combustion behavior of an inertinite-rich (87.7% dmmf) and a vitrinite-rich (91.8% dmmf) South African coal, wet-screened to a narrow particle size distribution of 200 x 400 mesh. Pyrolysis chars were generated under rapid-heating conditions (104-105 °C/s) in a drop-tube reactor to closely resemble chars generated in pulverized combustion conditions. The inertinite-rich coal took ~ 400 ms to devolatilize in the drop-tube, compared to only ~ 240 ms for the vitrinite-rich sample. The chemical and physical structure (the constitution) of the chars were investigated through a range of chemical, physical, and optical characteristics including the maceral differences, and high ash yields. To evaluate the combustion reactivity non-isothermal burn-out profiles were obtained through thermogravimetrical analyses (TGA) in air. The vitrinite-rich char had on average 20% higher reaction rates than the inertinite-rich char under the various combustion conditions. The char samples were de-ashed with HCl and HF acid which resulted in an increase in combustion reactivity. The maximum reaction rate of the high-ash (36% ash yield) inertinite-rich char increased with 80% after de-ashing. While the vitrinite-rich char with an ash yield of 15%, had a 20% increase in reactivity after de-ashing. The ash acted as a barrier, and the removal of ash most likely increased the access to reactive surface area. The chemical and physical structures of the chars were characterized through a range of different analytical techniques to quantify the factors contributing to reactivity differences. The morphologies of the chars

  13. Strategies and actions for the mitigation of the phenomenon DENTING in the tube sheet (TTS Denting) steam generators of the NPP Asco Denting at the top of the SG tube sheet (TTS tube denting) has recently been experienced in new and replacement SGs at several plants; Estrategias y acciones para la mitigacion del fenomeno DENTING en la placa tubular de generadores de vapor (TTS DENTING) de la Central Nuclear de Asco

    Energy Technology Data Exchange (ETDEWEB)

    Espanol Villar, J.

    2013-07-01

    It is highly likely that the accumulation of sludge (deposits) on the tube sheet is clearly associated with the denting occurrence. More specifically, it is commonly believed that an aggressive crevice environment formed within the deposits or in the shallow tight tube sheet to tube crevice below the deposits is at the origin of the denting (tube deformation), and, when present, the consequent stress corrosion cracking (SCC). There are described a set of strategies that have been followed since the emergence of the TTS denting phenomenon on Steam Generator of the Nuclear Power Plants Asco I and II, influenced by the presence of hard sludge in the tube plate of Steam Generators, their results and the evolution of the phenomenon in relation to the various measures taken.

  14. A new generation of versatile chromogenic substrates for high-throughput analysis of biomass-degrading enzymes

    DEFF Research Database (Denmark)

    Kracun, Stjepan Kresimir; Schückel, Julia; Westereng, Bjørge;

    2015-01-01

    Background: Enzymes that degrade or modify polysaccharides are widespread in pro- and eukaryotes and have multiple biological roles and biotechnological applications. Recent advances in genome and secretome sequencing, together with associated bioinformatic tools, have enabled large numbers...... of carbohydrate-acting enzymes to be putatively identified. However, there is a paucity of methods for rapidly screening the biochemical activities of these enzymes, and this is a serious bottleneck in the development of enzyme-reliant bio-refining processes. Results: We have developed a new generation of multi...... carbohydrate-acting enzymes, and the assays have the potential to be incorporated into fully or semi-automated robotic enzyme screening systems...

  15. Documentation Protocols to Generate Risk Indicators Regarding Degradation Processes for Cultural Heritage Risk Evaluation

    Science.gov (United States)

    Kioussi, A.; Karoglou, M.; Bakolas, A.; Labropoulos, K.; Moropoulou, A.

    2013-07-01

    Sustainable maintenance and preservation of cultural heritage assets depends highly on its resilience to external or internal alterations and to various hazards. Risk assessment of a heritage asset's can be defined as the identification of all potential hazards affecting it and the evaluation of the asset's vulnerability (building materials and building structure conservation state).Potential hazards for cultural heritage are complex and varying. The risk of decay and damage associated with monuments is not limited to certain long term natural processes, sudden events and human impact (macroscale of the heritage asset) but is also a function of the degradation processes within materials and structural elements due to physical and chemical procedures. Obviously, these factors cover different scales of the problem. The deteriorating processes in materials may be triggered by external influences or caused because of internal chemical and/or physical variations of materials properties and characteristics. Therefore risk evaluation should be dealt in the direction of revealing the specific active decay and damage mechanism both in mesoscale [type of decay and damage] and microscale [decay phenomenon mechanism] level. A prerequisite for risk indicators identification and development is the existence of an organised source of comparable and interoperable data about heritage assets under observation. This unified source of information offers a knowledge based background of the asset's vulnerability through the diagnosis of building materials' and building structure's conservation state, through the identification of all potential hazards affecting these and through mapping of its possible alterations during its entire life-time. In this framework the identification and analysis of risks regarding degradation processes for the development of qualitative and quantitative indicators can be supported by documentation protocols. The data investigated by such protocols help

  16. Effect of bending on useful properties of heat exchange tubes of steam generators for WWER type power plants

    Energy Technology Data Exchange (ETDEWEB)

    Jelen, L. (Vitkovicke Zelezarny Klementa Gottwalda, Ostrava (Czechoslovakia). Vyzkumny Ustav Materialu)

    1984-05-01

    For austenitic stainless steel 08Ch18N10T determinations were made of two material constants, the coefficients of strength and of deformation hardening, and of hardening curves which represent the dependence of the natural deformation resistance on the size of deformation. Tests of tube bending by overpressure showed that the weakening of the outer wall caused by bending is sufficiently offset by material hardening. The effect of cold deformation on material resistance to intergranular corrosion was studied. The effect of small deformations (3 to 10%) was not proved. Intergranular corrosion is limited by the quality of the surface of heat exchange tubes. The level was assessed of internal stress near bends with the following parameters: R=65 mm, ..cap alpha..=180deg. The presence of residual stress which would have unfavourable effect on the state of bending stress under operating load, was not observed.

  17. In vitro degradation and mechanical properties of PLA-PCL copolymer unit cell scaffolds generated by two-photon polymerization.

    Science.gov (United States)

    Felfel, R M; Poocza, Leander; Gimeno-Fabra, Miquel; Milde, Tobias; Hildebrand, Gerhard; Ahmed, Ifty; Scotchford, Colin; Sottile, Virginie; Grant, David M; Liefeith, Klaus

    2016-02-02

    The manufacture of 3D scaffolds with specific controlled porous architecture, defined microstructure and an adjustable degradation profile was achieved using two-photon polymerization (TPP) with a size of 2  ×  4  ×  2 mm(3). Scaffolds made from poly(D,L-lactide-co-ɛ-caprolactone) copolymer with varying lactic acid (LA) and ɛ -caprolactone (CL) ratios (LC16:4, 18:2 and 9:1) were generated via ring-opening-polymerization and photoactivation. The reactivity was quantified using photo-DSC, yielding a double bond conversion ranging from 70% to 90%. The pore sizes for all LC scaffolds were see 300 μm and throat sizes varied from 152 to 177 μm. In vitro degradation was conducted at different temperatures; 37, 50 and 65 °C. Change in compressive properties immersed at 37 °C over time was also measured. Variations in thermal, degradation and mechanical properties of the LC scaffolds were related to the LA/CL ratio. Scaffold LC16:4 showed significantly lower glass transition temperature (T g) (4.8 °C) in comparison with the LC 18:2 and 9:1 (see 32 °C). Rates of mass loss for the LC16:4 scaffolds at all temperatures were significantly lower than that for LC18:2 and 9:1. The degradation activation energies for scaffold materials ranged from 82.7 to 94.9 kJ mol(-1). A prediction for degradation time was applied through a correlation between long-term degradation studies at 37 °C and short-term studies at elevated temperatures (50 and 65 °C) using the half-life of mass loss (Time (M1/2)) parameter. However, the initial compressive moduli for LC18:2 and 9:1 scaffolds were 7 to 14 times higher than LC16:4 (see 0.27) which was suggested to be due to its higher CL content (20%). All scaffolds showed a gradual loss in their compressive strength and modulus over time as a result of progressive mass loss over time. The manufacturing process utilized and the scaffolds produced have potential for use in tissue engineering and regenerative medicine

  18. Transient analysis with high percentages steam generator tube plugging of Angra 1 nuclear power plant; Analise de transientes com altos percentuais de tamponamento dos tubos dos geradores de vapor de Angra 1

    Energy Technology Data Exchange (ETDEWEB)

    Lima, Marcio Poubel; Martins Junior, Laercio Lucena; Vanni, Enio Antonio; Machado, Marcio Dornellas; Moreira, Francisco Jose [ELETRONUCLEAR, Rio de Janeiro, RJ (Brazil); Alvim, Antonio Carlos M. [Universidade Federal, Rio de Janeiro, RJ (Brazil). Coordenacao dos Programas de Pos-graduacao de Engenharia. Programa de Engenharia Nuclear

    1999-11-01

    The present work is part of several analyses under development in ELETRONUCLEAR/ COPPE-UFRJ to evaluate impacts on licensing bases and operating conditions of an increase in steam generator tube plugging for Angra 1 NPP. Total loss of reactor coolant flow uncontrolled boron dilution transients were initially analysed. The final results indicated that were no impacts on FSAR established margins, in case of 24% steam generator tube plugging. (author) 3 refs., 4 figs., 4 tabs.

  19. Data for the inhibition effects of recombinant lamprey CRBGP on the tube formation of HUVECs and new blood vessel generation in CAM models

    Directory of Open Access Journals (Sweden)

    Qi Jiang

    2016-03-01

    Full Text Available In the present data article, lamprey cysteine-rich buccal gland protein (CRBGP which belongs to cysteine-rich secretory proteins (CRISPs family was recombinant and expressed in Rosetta blue cells. After identification, the recombinant protein was purified through affinity chromatograph. The inhibition effects of recombinant lamprey CRBGP (rL-CRBGP on tube formation of human umbilical vein endothelial cells (HUVECs and new blood vessel generation in chick chorioallantoic membrane (CAM models were analyzed. This paper contains data related to research concurrently published in “Anti-angiogenic activities of CRBGP from buccal glands of lampreys (Lampetra japonica” [1].

  20. Sound Tube Fixation Method of Micro Ringtone Airflow Piezoelectric Generator%微环音气流压电发电机声管固定方法

    Institute of Scientific and Technical Information of China (English)

    邹华杰; 陈荷娟; 赖长缨; 孙剑韬; 姜琦

    2014-01-01

    针对声管固定方法对微环音气流压电发电机最大输入功率的影响,提出了应用有限元和间边界元相结合的方法,对不同固定方法下的声管,数值模拟腔体受谐波(正弦波)激励的振动响应。在满足压电换能器最大机械功率条件下,选择合适的声管固定方法。结果表明:结构尺寸一定时,固支-固支固定有利于提高固有频率;结构尺寸越小,不同固定方法所对应的固有频率差异越大;固支-固支固定下,声管的基频较高且其偏差影响小。不同固定方法和不同尺寸下声管的谐响应和基频变化趋势,为微环音气流压电发电机的设计提供参考,也为进一步的换能器设计和验证实验提供了依据。%Methods of sound tube fixation the have great effect on the input power of micro-ringtone airflow piezoelectric generator.A finite element method combined with indirect boundary element method was proposed, harmonic responses of the sound tube with various fixation methods were analyzed.To maximize mechanical power of piezoelectric transducer,it should be choosing proper fixation methods of the sound tube.The result showed that:for the given structure size,clamped-clamped fixation method was beneficial to improve the natural frequency;the smaller size,the greater difference of natural frequency corresponded to various fixation meth-ods;clamped-clamped sound tube possessed higher fundamental frequency,and its deviation was small.The harmonic response and trend of fundamental frequency of sound tube with various fixing boundaries and different diameters could provide valuable reference for the design of micro-ringtone airflow piezoelectric generator;and it also provided the basis for further the design of transducer and experimental verification.

  1. Growth responses of Phragmites karka - a candidate for second generation biofuel from degraded saline lands

    Science.gov (United States)

    Zaheer Ahmed, Muhammad; Shoukat, Erum; Abideen, Zainul; Aziz, Irfan; Gulzar, Salman; Ajmal Khan, M.

    2017-04-01

    Global changes like rapidly increasing population, limited fresh water resources, increasing salinity and aridity are the major causes of land degradation. Increasing feed production for bioenergy through direct and indirect land use cause major threat to biodiversity besides competing with food resources. Growing halophytes on saline lands would provide alternate source of energy without compromising food and cash crop farming. Phragmites karkahas recently emerged as a potential bio-fuel crop, which maintains optimal growth at 100 mM NaCl with high ligno-cellulosic biomass. However, temporal and organ specific plant responses under salinity needs to be understood for effective management of degraded saline lands. This study was designed to investigate variation in growth, water relations, ion-flux, damage markers, soluble sugars, stomatal stoichiometry and photosynthetic responses of P. karka to short (0-7 days) and long (15-30 days) term exposure with 0 (control), 100 (moderate) and 300 (high) mM NaCl. A reduced shoot growth ( 45%) during earlier (within 7 days) phase was observed in 300 mM NaCl compared to control and moderate salinity. Reduced leaf elongation rate and leaf senescence from 7th day in 300 mM NaCl (and later in moderate salinity) correspond to increasing hydrogen peroxide and malondialdehyde contents. Leaf turgor loss represents the osmotic effect of NaCl at both concentrations, however turgor recovered completely in moderate salinity within a week. Plant appeared to use both organic solutes (soluble sugars) and ions (Na++K++Cl-) for osmotic adjustment along with improved water use efficiency under saline conditions. Turgor loss in high salinity (300 mM NaCl) was related to increased bulk elastic modulus and decreased hydraulic capacitance which ultimately resulted in low water potential. Leaf Na+ and Cl- accumulation increased earlier (from 7th day) in 300 mM NaCl and later in 100 mM. Higher ion sequestration in different organs was found in the

  2. Degradation of Organic Compounds by Active Species Sprayed in a Dielectric Barrier Corona Discharge System

    Institute of Scientific and Technical Information of China (English)

    LI Jie; SONG Ling; LIU Qiang; QU Guangzhou; LI Guofeng; WU Yan

    2009-01-01

    Investigation was made into the degradation of organic compounds by a dielectric barrier corona discharge (DBCD) system. The DBCD, consisting of a quartz tube, a concentric high voltage electrode and a net wrapped to the external wall (used as ground electrode), was introduced to generate active species which were sprayed into the organic solution through an aerator fixed on the bottom of the tube. The effect of four factors-the discharge voltage, gas flow rate, solution conductivity, and pH of wastewater, on the degradation efficiency of phenol was assessed. The obtained results demonstrated that this process was an effective method for phenol degradation. The degradation rate was enhanced with the increase in power supplied. The degradation efficiency in alkaline conditions was higher than those in acid and neutral conditions.The optimal gas flow rate for phenol degradation in the system was 1.6 L/min, while the solution conductivity had little effect on the degradation.

  3. A new generation of B(n)N(n) rings as a supplement to boron nitride tubes and cages.

    Science.gov (United States)

    Monajjemi, Majid; Boggs, James E

    2013-02-21

    In B(n)N(n) cages or tubes, when the quasi-borazine rings are attached to each other through a pair of common atoms of B and N, the bonding structure is named class A. On the other hand, there are some B(n)N(n) rings including a covalent bond between two atoms of B and N, which are named class B. In all previous studies, both reports of synthesis and theoretical calculation of boron nitride tubes and cages, the quasi-borazine units are attached together like class A. There are no theoretical or experimental reports from class B compounds except for a brief study in our previous works (Struct. Chem. 2012, 23, 551-580; J. Phys. Chem. C 2010, 114, 15315.). In this study, we have used two kinds of boron nitride rings from a twisted BN sheet in the same chirality created by different mechanisms. For (4, 4) chirality, the molecules B(16)N(16) and B(15)N(15) are found to respectively represent class A and B, and for (5, 5) chirality the molecules B(20)N(20) and B(18)N(18) are respectively again of class A and B. The structure of class A rings is similar to boron nitride tubes, but we have shown that it is impossible to produce a macromolecule of class B form as tubes or cages, because there is much more instability and intermolecular tension in macro forms of class B. This is the main reason that the class B molecules are rare and, because of their small size, have not yet been synthesized, although we have some suggestions for the synthesis of these kinds of molecules. The stability and electromagnetic properties with hybrid density functional theory using the EPR-III and EPR-II basis sets for explanation of hyperfine parameters and spin densities, electrical potential, and isotropic Fermi coupling constant of these rings have been studied by the nonbonded interaction models. Normal mode analyses including aromaticity have been investigated by using the nucleus independent chemical shift values at the ring center. Interaction energy and gain in energy aid in describing

  4. Deposits on the secondary side of the steam generators: Causes and consequences; Depositos en el lado secundario de los generadores de vapor: causas y consecuencias

    Energy Technology Data Exchange (ETDEWEB)

    Gomez-Briceno, D.; Yague, C.; Fernandez Diaz, M.; Gomez Mancebo, B.; Fernandez Saavedra, R.

    2013-07-01

    Despite improvements in the control of the chemistry of the secondary circuit of the PWR type reactor, large amounts of corrosion products are incorporated in the steam generators and deposited on the surface of the tubes, on the flow holes the support plates and the tubes sheet. Magnetite accumulated on the tube sheet undergoes consolidation giving rise to what is known as hard sludge, which reduces heat transfer and induces a temperature rise in the tubes which will favor the possible processes degradation. Hard sludge accumulation has been identified as a necessary condition for degradation by denting of the tubes of steam generators found in Almaraz and Asco NPP: In this article, we discuss the causes of the accumulation of deposits and their effects on the degradation of the tubes of the steam generators. (Author)

  5. Cardiac protection by preconditioning is generated via an iron-signal created by proteasomal degradation of iron proteins.

    Directory of Open Access Journals (Sweden)

    Baruch E Bulvik

    Full Text Available Ischemia associated injury of the myocardium is caused by oxidative damage during reperfusion. Myocardial protection by ischemic preconditioning (IPC was shown to be mediated by a transient 'iron-signal' that leads to the accumulation of apoferritin and sequestration of reactive iron released during the ischemia. Here we identified the source of this 'iron signal' and evaluated its role in the mechanisms of cardiac protection by hypoxic preconditioning. Rat hearts were retrogradely perfused and the effect of proteasomal and lysosomal protease inhibitors on ferritin levels were measured. The iron-signal was abolished, ferritin levels were not increased and cardiac protection was diminished by inhibition of the proteasome prior to IPC. Similarly, double amounts of ferritin and better recovery after ex vivo ischemia-and-reperfusion (I/R were found in hearts from in vivo hypoxia pre-conditioned animals. IPC followed by normoxic perfusion for 30 min ('delay' prior to I/R caused a reduced ferritin accumulation at the end of the ischemia phase and reduced protection. Full restoration of the IPC-mediated cardiac protection was achieved by employing lysosomal inhibitors during the 'delay'. In conclusion, proteasomal protein degradation of iron-proteins causes the generation of the 'iron-signal' by IPC, ensuing de-novo apoferritin synthesis and thus, sequestering reactive iron. Lysosomal proteases are involved in subsequent ferritin breakdown as revealed by the use of specific pathway inhibitors during the 'delay'. We suggest that proteasomal iron-protein degradation is a stress response causing an expeditious cytosolic iron release thus, altering iron homeostasis to protect the myocardium during I/R, while lysosomal ferritin degradation is part of housekeeping iron homeostasis.

  6. Development of the data base for a degradation model of a selenide RTG. [Radioisotope Thermoelectric Generator

    Science.gov (United States)

    Stapfer, G.; Truscello, V. C.

    1977-01-01

    The paper is concerned with the evaluation of the materials used in a selenide radioisotope thermoelectric generator (RTG). These materials are composed of n-type gadolinium selenide and n-type copper selenide. A three-fold evaluation approach is being used: (1) the study of the rate of change of the thermal conductivity of the material, (2) the investigation of the long-term stability of the material's Seebeck voltage and electrical resistivity under current and temperature gradient conditions, and (3) determination of the physical behavior and compatibility of the material with surrounding insulation at elevated temperatures. Programmatically, the third category of characteristic evaluation is being emphasized.

  7. Generation of an artificial skin construct containing a non-degradable fiber mesh: a potential transcutaneous interface

    Energy Technology Data Exchange (ETDEWEB)

    Cahn, Frederick [Biomedical Strategies Inc., San Diego, CA (United States); Kyriakides, Themis R [Vascular Biology and Therapeutics, Yale University, New Haven, CT 06536-9812 (United States)], E-mail: themis.kyriakides@yale.edu

    2008-09-01

    Generation of a stable interface between soft tissues and biomaterials could improve the function of transcutaneous prostheses, primarily by minimizing chronic infections. We hypothesized that inclusion of non-biodegradable biomaterials in an artificial skin substrate would improve integration of the neodermis. In the present study, we compared the biocompatibility of an experimental substrate, consisting of collagen and glycosylaminoglycans, with commercially available artificial skin of similar composition. By utilizing a mouse excisional wound model, we found that the source of collagen (bovine tendon versus hide), extent of injury and wound contraction were critical determinants of inflammation and neodermis formation. Reducing the extent of injury to underlying muscle reduced inflammation and improved remodeling; the improved conditions allowed the detection of a pro-inflammatory effect of hide-derived collagen. To eliminate the complication of wound contraction, subsequent grafts were performed in guinea pigs and showed that inclusion of carbon fibers or non-degradable sutures resulted in increased foreign body response (FBR) and altered remodeling. On the other hand, inclusion of a polyester multi-stranded mesh induced a mild FBR and allowed normal neodermis formation. Taken together, our observations suggest that non-degradable biomaterials can be embedded in an artificial skin construct without compromising its ability to induce neodermis formation.

  8. Electricity generation and pollutant degradation using a novel biocathode coupled photoelectrochemical cell.

    Science.gov (United States)

    Du, Yue; Feng, Yujie; Qu, Youpeng; Liu, Jia; Ren, Nanqi; Liu, Hong

    2014-07-01

    The photoelectrochemical cell (PEC) is a promising tool for the degradation of organic pollutants and simultaneous electricity recovery, however, current cathode catalysts suffer from high costs and short service lives. Herein, we present a novel biocathode coupled PEC (Bio-PEC) integrating the advantages of photocatalytic anode and biocathode. Electrochemical anodized TiO2 nanotube arrays fabricated on Ti substrate were used as Bio-PEC anodes. Field-emission scanning electron microscope images revealed that the well-aligned TiO2 nanotubes had inner diameters of 60-100 nm and wall-thicknesses of about 5 nm. Linear sweep voltammetry presented the pronounced photocurrent output (325 μA/cm(2)) under xenon illumination, compared with that under dark conditions. Comparing studies were carried out between the Bio-PEC and PECs with Pt/C cathodes. The results showed that the performance of Pt/C cathodes was closely related with the structure and Pt/C loading amounts of cathodes, while the Bio-PEC achieved similar methyl orange (MO) decoloration rate (0.0120 min(-1)) and maximum power density (211.32 mW/m(2)) to the brush cathode PEC with 50 mg Pt/C loading (Brush-PEC, 50 mg). The fill factors of Bio-PEC and Brush-PEC (50 mg) were 39.87% and 43.06%, respectively. The charge transfer resistance of biocathode was 13.10 Ω, larger than the brush cathode with 50 mg Pt/C (10.68 Ω), but smaller than the brush cathode with 35 mg Pt/C (18.35 Ω), indicating the comparable catalytic activity with Pt/C catalyst. The biocathode was more dependent on the nutrient diffusion, such as nitrogen and inorganic carbon, thus resulting in relatively higher diffusion resistance compared to the brush cathode with 50 mg Pt/C loading that yielded similar MO removal and power output. Considering the performance and cost of PEC system, the biocathode was a promising alternative for the Pt/C catalyst.

  9. Degradation of perfluoro compounds and f{sup -} recovery in water using discharge plasmas generated within gas bubbles

    Energy Technology Data Exchange (ETDEWEB)

    Yasuoka, K.; Sasaki, K.; Hayashi, R.; Kosugi, A.; Takeuchi, N. [Tokyo Inst. of Technology, Tokyo (Japan). Dept. of Electrical and Electronic Engineering

    2010-07-01

    The widespread use of perfluorocarbons (PFCs) has raised environmental concerns because of their chemical stability and the toxicity of long-chain PFCs. Since PFCs such as perfluorooctanoic acid (PFOA) or perfluorooctanesulfonic acid (PFOS) cannot be decomposed by advanced oxidation technologies utilizing OH radicals, other methods have been tested to decompose their strong C-F bonds. Recent studies have shown that direct plasma-water interaction can easily decompose such persistent substances in water. A DC plasma generated within oxygen bubbles in water showed a higher decomposition rate and efficiency than pulsed plasmas. During decomposition, fluorine ions were generated in the solution. The recovery of fluorine from PFOA in water was tested by combining the PFOA decomposition process and calcium precipitation method. The recovery of fluorine is important due to the increasing price of fluorite. The PFC decomposing rate and efficiency were evaluated by measuring the fluorine ions generated in the solution. The decomposing rate for PFOA was slightly higher than that for PFOS. The direct plasma interaction to the solution surfaces appeared to enhance the degradation of PFOA/PFOS. 10 refs., 1 tab., 9 figs.

  10. Silver quantum cluster (ag9 )-grafted graphitic carbon nitride nanosheets for photocatalytic hydrogen generation and dye degradation.

    Science.gov (United States)

    Sridharan, Kishore; Jang, Eunyong; Park, Jung Hyun; Kim, Jong-Ho; Lee, Jung-Ho; Park, Tae Joo

    2015-06-15

    We report the visible-light photocatalytic properties of a composite system consisting of silver quantum clusters [Ag9 (H2 MSA)7 ] (H2 MSA=mercaptosuccinic acid) embedded on graphitic carbon nitride nanosheets (AgQCs-GCN). The composites were prepared through a simple chemical route; their structural, chemical, morphological, and optical properties were characterized by using X-ray diffraction (XRD), energy dispersive X-ray spectroscopy, transmission electron microscopy, UV/Vis diffuse reflectance spectroscopy, and photoluminescence spectroscopy. Embedment of [Ag9 (H2 MSA)7 ] on graphitic carbon nitride nanosheets (GCN) resulted in extended visible-light absorption through multiple single-electron transitions in Ag quantum clusters and an effective electronic structure for hydroxyl radical generation, which enabled increased activity in the photocatalytic degradation of methylene blue and methyl orange dye molecules compared with pristine GCN and silver nanoparticle-grafted GCN (AgNPs-GCN). Similarly, the amount of hydrogen generated by using AgQCs-GCN was 1.7 times higher than pristine GCN. However, the rate of hydrogen generated using AgQCs-GCN was slightly less than that of AgNPs-GCN because of surface hydroxyl radical formation. The plausible photocatalytic processes are discussed in detail.

  11. Diagnostic technology for degradation of feeder pipes and fuel channels in CANDU reactor; development of aging assessment technology for CANDU pressure tubes

    Energy Technology Data Exchange (ETDEWEB)

    Kim, Young Jin; Kim, Yun Jae; Huh, Nam Su; Kwak, Sang Log; Lee, Kyu Ho [Sungkyunkwan University, Seoul (Korea)

    2002-04-01

    This research project attempts to resolve two issues related to integrity assessment of CANDU pressure tubes; (1) FE analysis of blister formation and growth, and (2) engineering estimation scheme to predict creep deflection of pressure tubes. Results for blister formation and growth can be summarised as follows. Comparing the results from the FE analysis, developed within this project, with experimental data shows some differences ranging from 10-57%. Such difference results from two possible sources. One source is neglecting two phase diffusion. The present FE analysis considers only single phase diffusion, and thus blister growth can not be accurately modeled. The other source would be inherent errors associated with experimental measurement. Thus it has been concluded that further efforts should be made on two phase diffusion modeling. For developing mechanistic model of creep deflection, the proposed reference stress based model is simple to use. Extensive validation against creep FE results shows that the proposed model is also quite accurate. More important aspect of the proposed method is that it can be easily generalized to more complex problems. Thus it is believed that the present results provide a sound basis for sagging assessment of CANDU pressure tubes. 16 refs., 12 figs., 6 tabs. (Author)

  12. Structural and leakage integrity of tubes affected by circumferential cracking

    Energy Technology Data Exchange (ETDEWEB)

    Hernalsteen, P. [TRACTEBEL, Brussels (Belgium)

    1997-02-01

    In this paper the author deals with the notion that circumferential cracks are generally considered unacceptable. He argues for the need to differentiate two facets of such cracks: the issue of the size and growth rate of a crack; and the issue of the structural strength and leakage potential of the tube in the presence of the crack. In this paper the author tries to show that the second point is not a major concern for such cracks. The paper presents data on the structural strength or burst pressure characteristics of steam generator tubes derived from models and data bases of experimental work. He also presents a leak rate model, and compares the performance of circumferential and axial cracks as far as burst strength and leak rate. The final conclusion is that subject to improvement in NDE capabilities (sizing, detection, growth), that Steam Generator Defect Specific Management can be used to allow circumferentially degraded tubes to remain in service.

  13. Electron Emission And Beam Generation Using Ferroelectric Cathodes (electron Beam Generation, Lead Lanthanum Zicronate Titanate, High Power Traveling Wave Tube Amplfier)

    CERN Document Server

    Flechtner, D D

    1999-01-01

    In 1989, researchers at CERN published the discovery of significant electron emission (1– 100 A/cm2) from Lead- Lanthanum-Zirconate-Titanate (PLZT). The publication of these results led to international interest in ferroelectric cathodes studies for use in pulsed power devices. At Cornell University in 1991, experiments with Lead-Zirconate-Titanate (PZT) compositions were begun to study the feasibility of using this ferroelectric material as a cathode in the electron gun section of High Power Traveling Wave Tube Amplifier Experiments. Current-voltage characteristics were documented for diode voltages ranging from 50– 500,000 V with anode cathode gaps of.5– 6 cm. A linear current-voltage relation was found for voltages less than 50 kV. For diode voltages ≥ 200 kV, a typical Child-Langmuir V3/2 dependence was observed...

  14. Bioelectricity generation and dewatered sludge degradation in microbial capacitive desalination cell.

    Science.gov (United States)

    Meng, Fanyu; Zhao, Qingliang; Na, Xiaolin; Zheng, Zhen; Jiang, Junqiu; Wei, Liangliang; Zhang, Jun

    2016-05-18

    Microbial desalination cell (MDC) is a new approach for the synergy in bioelectricity generation, desalination and organic waste treatment without additional power input. However, current MDC systems cause salt accumulation in anodic wastewater and sludge. A microbial capacitive desalination cell (MCDC) with dewatered sludge as anodic substrate was developed to address the salt migration problem and improve the sludge recycling value by special designed-membrane assemblies, which consisted of cation exchange membranes (CEMs), layers of activated carbon cloth (ACC), and nickel foam. Experimental results indicated that the maximum power output of 2.06 W/m(3) with open circuit voltage (OCV) of 0.942 V was produced in 42 days. When initial NaCl concentration was 2 g/L, the desalinization rate was about 15.5 mg/(L·h) in the first 24 h, indicating that the MCDC reactor was suitable to desalinize the low concentration salt solution rapidly. The conductivity of the anodic substrate decreased during the 42-day operation; the CEM/ACC/Ni assemblies could effectively restrict the salt accumulation in MCDC anode and promote dewatered sludge effective use by optimizing the dewatered sludge properties, such as organic matter, C/N, pH value, and electric conductivity (EC).

  15. 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 within...

  16. Tracheostomy tubes.

    Science.gov (United States)

    Hess, Dean R; Altobelli, Neila P

    2014-06-01

    Tracheostomy tubes are used to administer positive-pressure ventilation, to provide a patent airway, and to provide access to the lower respiratory tract for airway clearance. They are available in a variety of sizes and styles from several manufacturers. The dimensions of tracheostomy tubes are given by their inner diameter, outer diameter, length, and curvature. Differences in dimensions between tubes with the same inner diameter from different manufacturers are not commonly appreciated but may have important clinical implications. Tracheostomy tubes can be cuffed or uncuffed and may be fenestrated. Some tracheostomy tubes are designed with an inner cannula. It is important for clinicians caring for patients with a tracheostomy tube to appreciate the nuances of various tracheostomy tube designs and to select a tube that appropriately fits the patient. The optimal frequency of changing a chronic tracheostomy tube is controversial. Specialized teams may be useful in managing patients with a tracheostomy. Speech can be facilitated with a speaking valve in patients with a tracheostomy tube who are breathing spontaneously. In mechanically ventilated patients with a tracheostomy, a talking tracheostomy tube, a deflated cuff technique with a speaking valve, or a deflated cuff technique without a speaking valve can be used to facilitate speech. Copyright © 2014 by Daedalus Enterprises.

  17. Involvement of Hydrogen Peroxide Generated by Polyamine Oxidative Degradation in the Development of Lateral Roots in Soybean

    Institute of Scientific and Technical Information of China (English)

    2006-01-01

    In order to determine whether hydrogen peroxide (H2O2) generated by polyamine oxidative degradation is involved in the development of lateral roots in soybean, the length and the number of lateral roots, the activities of polyamine oxidases and diamine oxidases, and the endogenous free polyamine and H2O2 content were analyzed in soybean (Glycine max (Linn.) Merr.) main roots of 2-d-old seedlings after treatments for 2 d with exogenous β-hydroxyethylhydrazine (an inhibitor of polyamine oxidases), H2O2, putrescine, cyclohexylamine (an inhibitor of spermidine synthase) or N,N'-dimethylthiourea (a scavenger of hydrogen peroxide).β-hydroxyethylhydrazine treatment strongly inhibited the development of lateral roots in soybean seedlings,reduced the activities of polyamine oxidases and diamine oxidases, decreased H2O2 levels, and led to the accumulation of endogenous polyamines in the main roots. The inhibitory effect of β-hydroxyethylhydrazine on root development could be alleviated by exogenously applied 10 μmol/L H2O2 (a major product of polyamine oxidation). Treatment with cyclohexylamine and putrescine promoted root growth slightly, but treatment with cyclohexylamine plus N,N'-dimethylthiourea or putrescine plus N,N'-dimethylthiourea prevented the development of soybean lateral roots. The effects of these treatments on the development of soybean lateral roots were consistent with the changes in endogenous H2O2 levels. These results suggest that the development of soybean lateral roots is associated with the oxidative degradation of polyamines, and that their products,especially H2O2, are likely to play an important role in the growth of soybean lateral roots.

  18. Fundamental understanding of the thermal degradation mechanisms of waste tires and their air pollutant generation in a N2 atmosphere.

    Science.gov (United States)

    Kwon, Eilhann; Castaldi, Marco J

    2009-08-01

    The thermal decomposition of waste tires has been characterized via thermo-gravimetric analysis (TGA) tests, and significant mass loss has been observed between 300 and 500 degrees C. A series of gas chromatography-mass spectrometer (GC-MS) measurements, in which the instrument was coupled to a TGA unit, have been carried out to investigate the thermal degradation mechanisms as well as the air pollutant generation including volatile organic carbons (VOCs) and polycyclic aromatic hydrocarbons (PAHs) in a nitrogen atmosphere. In order to understand fundamental information on the thermal degradation mechanisms of waste tires, the main constituents of tires, poly-isoprene rubber (IR) and styrene butadiene rubber (SBR), have been studied under the same conditions. All of the experimental work indicated that the bond scission on each monomer of the main constituents of tires was followed by hydrogenation and gas phase reactions. This helped to clarify the independent pathways and species attributable to IR and SBR during the pyrolysis process. To extend that understanding to a more practical level, a flow-through reactor was used to test waste tire, SBR and IR samples in the temperature range of 500-800 degrees C at a heating rate of approximately 200 degrees C. Lastly, the formation of VOCs (approximately 1-50 PPMV/10 mg of sample) and PAHs (approximately 0.2-7 PPMV/10 mg of sample) was observed at relatively low temperatures compared to conventional fuels, and its quantified concentration was significantly high due to the chemical structure of SBR and IR. The measurement of chemicals released during pyrolysis suggests not only a methodology for reducing the air pollutants but also the feasibility of petrochemical recovery during thermal treatment.

  19. A gas laser tube

    Energy Technology Data Exchange (ETDEWEB)

    Tetsuo, F.; Tokhikhide, N.

    1984-04-19

    A gas laser tube is described in which contamination of the laser gas mixture by the coolant is avoided, resulting in a longer service life of the mirrors. The holder contains two tubes, one inside the other. The laser gas mixture flows through the internal tube. An electrode is fastened to the holder. The coolant is pumped through the slot between the two tubes, for which a hole is cut into the holder. The external tube has a ring which serves to seal the cavity containing the coolant from the atmosphere. The internal tube has two rings, one to seal the laser gas mixture and the other to seal the coolant. A slot is located between these two rings, which leads to the atmosphere (the atmosphere layer). With this configuration, the degradation of the sealing properties of the internal ring caused by interaction with the atmospheric layer is not reflected in the purity of the laser gas mixture. Moreover, pollution of the mirrors caused by the penetration of the coolant into the cavity is eliminated.

  20. Use of a packed-bed airlift reactor with net draft tube to study kinetics of naphthalene degradation by Ralstonia eutropha.

    Science.gov (United States)

    Jalilnejad, Elham; Vahabzadeh, Farzaneh

    2014-03-01

    Biodegradation of naphthalene by Ralstonia eutropha (also known as Cupriavidus necator) in a packed-bed airlift reactor with net draft tube (PBALR-nd) was studied; the Kissiris pieces were the packing material. The reactor hydrodynamics has been characterized under abiotic conditions and the dependencies of the superficial gas velocity (U G) on the gas holdup (εG), liquid mixing time, and mass transfer coefficient were determined. The improving role of the net draft tube in this small column reactor (height 42 cm, ID 5 cm) was confirmed. The flow regime was described using the εG α U G (n) expression, and bubbly flow was observed in PBALR-nd at U G kinetics of biodegradation was modeled using the Haldane and Aiba equations. The fitting of the experimental results to the models were done according to the nonlinear least square regression technique. The biokinetic constants (q m, K s, and K i) were estimated and q m as the specific biodegradation rate was equaled to 0.415 and 0.24 mgnaph./mgcell h for the Haldane and Aiba equations, respectively. The goodness of fit reported as R (2) and root-mean-square error (RMSE) showed the adequate fitness of the Haldane and Aiba models in predicting naphthalene biodegradation kinetics. On the basis of the HPLC results, a hypothetical pathway for the biodegradation was presented.

  1. Supplementary examination of alternative materials in a model steam generator: Volume 3, tube characterization by metallography and transmission electron microscopy: Final report

    Energy Technology Data Exchange (ETDEWEB)

    Krupowicz, J.J.; Stubbins, J.F.; Mehler, M.

    1988-10-01

    The microstructural characteristics of current and candidate alloys for steam generator heat transfer tubing were determined utilizing a variety of techniques. Mill annealed heats of Alloys 690 and 800NG were examined as well as heats of Alloy 600 in the mill annealed, process stabilized, sensitized and thermally treated conditions. Characterization included optical microscopy, transmission electron microscopy and scanning transmission electron microscopy of these materials in their pre- and post-test conditions (i.e., archive and exposure for 11,328 hours to 621/degree/F primary temperature). The results were utilized to elicit comparisons of these materials to stress corrosion cracking resistance in sulfate faulted secondary environments. 83 figs., 8 tabs.

  2. Sonochemical degradation of methyl orange in the presence of Bi2WO6: Effect of operating parameters and the generated reactive oxygen species.

    Science.gov (United States)

    He, Ling-Ling; Liu, Xian-Ping; Wang, Yong-Xia; Wang, Zhi-Xin; Yang, Yan-Jie; Gao, Yan-Ping; Liu, Bin; Wang, Xin

    2016-11-01

    The Bi2WO6 was prepared by the hydrothermal method and its sonocatalytic activity was studied in the degradation of methyl orange (MO) solutions. The effects of catalytic activity of Bi2WO6 on dye were inspected by the change in absorbance of dye with UV-vis spectrometer. The influences of operational parameters such as the addition amount of Bi2WO6, pH, the initial concentration of dyes, ultrasonic power and irradiation time on the degradation ratio were investigated. In addition, the obtained results indicated that the kinetics of sonochemical reactions of MO were consistent with the pseudo first-order kinetics and Bi2WO6 had excellent reusability and stability during the sonochemical degradation processes. The generation and kinds of reactive oxygen species (ROS) and their influence on the sonochemical degradation of MO were determined by the methods of oxidation-extraction spectrophotometry and ROS scavengers. The results indicate that the degradation of MO in the presence of Bi2WO6 under ultrasonic irradiation is related to the generation of ROS, in which both singlet molecular oxygen ((1)O2) and hydroxyl radical (OH) play important roles in the sonochemical degradation of MO. These experimental results provide a sound foundation for the further development of Bi2WO6 as a sonocatalyst in wastewater treatment.

  3. Data bank on hydrodynamics, thermal tests and tube temperature regimes of PGV-4 and PVG-1000 natural steam generators

    Energy Technology Data Exchange (ETDEWEB)

    Ageev, A.G.; Vasileva, R.V.; Nigmatulin, B.I.; Titov, V.F.; Tarankov, G.N. [EREC Electrogorsk Research and Engineering Centre of Nuclear Plants Safety, Moscow (Russian Federation)

    1995-12-31

    The data bank was prepared by EREC, OKB `Hydropress` using results of static and dynamic tests of PGV-4 and PGV- 1000 natural steam generators cared out at Kolskaya, Novo-Voronezhskaya, Ugno-Ukrainskaya, Balakov-skaya and Hmelnitskaya NPP within period of 1974-1993. It is destined for making calculation codes verification. (authors).

  4. Prospectively ECG-triggered high-pitch coronary angiography with third-generation dual-source CT at 70 kVp tube voltage: feasibility, image quality, radiation dose, and effect of iterative reconstruction.

    Science.gov (United States)

    Hell, Michaela M; Bittner, Daniel; Schuhbaeck, Annika; Muschiol, Gerd; Brand, Michael; Lell, Michael; Uder, Michael; Achenbach, Stephan; Marwan, Mohamed

    2014-01-01

    Low tube voltage reduces radiation exposure in coronary CT angiography (CTA). Using 70 kVp tube potential has so far not been possible because CT systems were unable to provide sufficiently high tube current with low voltage. We evaluated feasibility, image quality (IQ), and radiation dose of coronary CTA using a third-generation dual-source CT system capable of producing 450 mAs tube current at 70 kVp tube voltage. Coronary CTA was performed in 26 consecutive patients with suspected coronary artery disease, selected for body weight Image noise was lower in IR vs FBP (60 ± 10 HU vs 74 ± 8 HU; P < .001). In patients <100 kg and with a regular heart rate <60 beats/min, third-generation dual-source CT using high-pitch spiral acquisition and 70 kVp tube voltage is feasible and provides both robust IQ and very low radiation exposure. Copyright © 2014 Society of Cardiovascular Computed Tomography. Published by Elsevier Inc. All rights reserved.

  5. Dust Degradation of Apollo Lunar Laser Retroreflectors and the Implications for the Next Generation Lunar Laser Retroreflectors

    Science.gov (United States)

    Currie, D. G.; Delle Monache, G.; Dell'Agnello, S.; Murphy, T.

    2013-12-01

    The Apollo Lunar Laser Retroreflectors deployed during Apollo 11, 14 and 15 are still operating after 44 years and producing unique new science addressing some of the best tests of General Relativity (e. g., the Strong Equivalence Principle, the inertial properties of gravitational fields and constraints on the temporal and spatial variation of the gravitational constant -G) and lunar physics (e. g., the discover and parameters of the inner liquid core, the free librations, and various crustal properties). However, the magnitude of the return signal has decreased by a factor ten to one hundred since the arrays were deployed. While this degradation in the signal level has not decreased the ranging accuracy from which the science is derived, the source and behavior of the cause must be addressed within the current program to develop the next generation Lunar laser retroreflector, that is, the 'Lunar Laser Ranging Retroreflector Array for the 21st Century' or LLRRA-21. During lunar night, the return signal strength is about 10% of the expected signal strength, based upon an analysis of the ground station and retroreflector arrays. Around full moon, the signal level drops to about 1% of the expected return. While a deposit of lunar dust on the front faces of the Cube Corner Reflectors (CCRs) is the most likely candidate, other causes have been postulated: darkening due to UV and/or particle exposure, micrometeorite bombardment or change in the properties of the thermal coating due to dust, UV and or particle exposure. The dust may be due to secondary eject from micrometeorite impacts in the near vicinity, electrically levitated dust and/or dust from the LEM liftoff. Again, understanding the causes of this degradation is critical in the design of the LLRRA-21, impacting the design of the current sun/dust shade, choice of thermal control surfaces etc. Crucial observational data has been obtained by a recent set of observation during a lunar eclipse by the APOLLO ranging

  6. Eddy-current tests on operational evaluation of steam generator tubes in nuclear power plants; Ensaios de Eddy-current na avaliacao do estado operacional de tubos de geradores de vapor de centrais nucleares

    Energy Technology Data Exchange (ETDEWEB)

    Lopez, Luiz Antonio Negro Martin [Faculdade de Engenharia Industrial (FEI), Sao Paulo, SP (Brazil). Dept. de Energetica]. E-mail: luizlope@cci.fei.br; Ting, Daniel Kao Sun [Instituto de Pesquisas Energeticas e Nucleares (IPEN-CNEN/SP), Sao Paulo, SP (Brazil). Dept. Engenharia de Reatores]. E-mail: dksting@net.ipen.br

    2000-07-01

    This paper presents a worldwide research on the technical and economical impacts due to failure in tube bundles of nuclear power plant steam generators. An Eddy current non destructive test using Foucault currents for the inspection and failure detection on the tubes, and also the main type of defects. The paper also presents the signals generated by a Zetec MIZ-40 test equipment. This paper also presents a brief description of an automatic system for data analysis which is under development by using a fuzzy logic and artificial intelligence.

  7. The criterion for blanking-off heat-transfer tubes in the steam generators at VVER-based nuclear power plants based on the results of eddy-current examination

    Science.gov (United States)

    Lunin, V. P.; Zhdanov, A. G.; Chegodaev, V. V.; Stolyarov, A. A.

    2015-05-01

    The problem of defining the criterion for blanking off heat-transfer tubes in the steam generators at nuclear power plants on the basis of signals obtained from the standard multifrequency eddy-current examination is considered. The decision about blanking off one or another tube is presently made with reference to one parameter of the relevant signal at the working frequency, namely, with reference to its phase, which directly depends on the depth of the flaw being detected, i.e., a crack in the tube. The crack depth equal to 60% of the tube wall thickness is regarded to be the critical one, at which a decision about withdrawing such a tube out from operation (blanking off) must be taken. However, since mechanical tensile rupture tests of heat-transfer tubes show the possibility of their further use with such flaws, the secondary parameter of the signal, namely, its amplitude, must be used for determining the blanking-off criterion. The signals produced by the standard flow-type transducers in response to flaws in the form of a longitudinal crack having the depth and length within the limits permitted by the relevant regulations were calculated using 3D finite-element modeling. Based on the obtained results, the values of the eddy-current signal amplitude were determined, which, together with the signal phase value, form a new amplitude-phase criterion for blanking off heat-transfer tubes. For confirming the effectiveness of this technique, the algorithm for revealing the signal indications satisfying the proposed amplitude-phase criterion was tested on real signals obtained from operational eddy-current examination of the state of steam generator heat-transfer tubes carried out within the framework of planned preventive repair.

  8. Pump element for a tube pump

    DEFF Research Database (Denmark)

    2011-01-01

    relative to the rod element so as to allow for a fluid flow in the tube through the first valve member, along the rod element, and through the second valve member. The tube comprises an at least partly flexible tube portion between the valve members such that a repeated deformation of the flexible tube...... 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...

  9. Tube-Forming Assays.

    Science.gov (United States)

    Brown, Ryan M; Meah, Christopher J; Heath, Victoria L; Styles, Iain B; Bicknell, Roy

    2016-01-01

    Angiogenesis involves the generation of new blood vessels from the existing vasculature and is dependent on many growth factors and signaling events. In vivo angiogenesis is dynamic and complex, meaning assays are commonly utilized to explore specific targets for research into this area. Tube-forming assays offer an excellent overview of the molecular processes in angiogenesis. The Matrigel tube forming assay is a simple-to-implement but powerful tool for identifying biomolecules involved in angiogenesis. A detailed experimental protocol on the implementation of the assay is described in conjunction with an in-depth review of methods that can be applied to the analysis of the tube formation. In addition, an ImageJ plug-in is presented which allows automatic quantification of tube images reducing analysis times while removing user bias and subjectivity.

  10. myo-Inositol phosphate isomers generated by the action of a phytate-degrading enzyme from Klebsiella terrigena on phytate

    National Research Council Canada - National Science Library

    Greiner, Ralf; Carlsson, Nils-Gunnar

    2006-01-01

    .... The phytate-degrading enzyme of Klebsiella terrigena degrades myo-inositol hexakisphosphate by stepwise dephosphorylation, preferably via D-Ins(1,2,4,5,6)P5, D-Ins(1,2,5,6)P4, D-Ins(1,2,6)P3, D-Ins(1,2...

  11. Characterization of cysteine-degrading and H2S-releasing enzymes of higher plants - From the field to the test tube and back

    DEFF Research Database (Denmark)

    Jutta, Papenbrock; Anja, Riemenschneider; Kamp, Anja;

    2007-01-01

    in plants which might be involved in SIR, such as high levels of thiols, glucosinolates, cysteine-rich proteins, phytoalexins, elemental sulfur, or H2S. Probably more than one strategy is used by plants. Species- or even variety-dependent differences in the development of SIR are probably used. Our research...... focussed mainly on the release of H2S as defence strategy. In field experiments using different Brassica napus genotypes it was shown that the genetic differ- ences among Brassica genotypes lead to differences in sulfur content and L-cysteine desulfhydrase activity. Another field ex- periment demonstrated...... that sulfur supply and infection with Pyrenopeziza brassica influenced L-cysteine desulfhydrase activity in Brassica napus. Cysteine-degrading enzymes such as cysteine desulfhydrases are hypothesized to be involved in H2S release. Several L- and D-cysteine-specific desulfhydrase candidates have been isolated...

  12. Characterization of cysteine-degrading and H2S-releasing enzymes of higher plants - From the field to the test tube and back

    DEFF Research Database (Denmark)

    Jutta, Papenbrock; Anja, Riemenschneider; Kamp, Anja

    2007-01-01

    in plants which might be involved in SIR, such as high levels of thiols, glucosinolates, cysteine-rich proteins, phytoalexins, elemental sulfur, or H2S. Probably more than one strategy is used by plants. Species- or even variety-dependent differences in the development of SIR are probably used. Our research...... focussed mainly on the release of H2S as defence strategy. In field experiments using different Brassica napus genotypes it was shown that the genetic differ- ences among Brassica genotypes lead to differences in sulfur content and L-cysteine desulfhydrase activity. Another field ex- periment demonstrated...... that sulfur supply and infection with Pyrenopeziza brassica influenced L-cysteine desulfhydrase activity in Brassica napus. Cysteine-degrading enzymes such as cysteine desulfhydrases are hypothesized to be involved in H2S release. Several L- and D-cysteine-specific desulfhydrase candidates have been isolated...

  13. Free Piston Double Diaphragm Shock Tube

    OpenAIRE

    OGURA, Eiji; FUNABIKI, Katsushi; SATO, Shunichi; Abe, Takashi; 小倉, 栄二; 船曳, 勝之; 佐藤, 俊逸; 安部, 隆士

    1997-01-01

    A free piston double diaphragm shock tube was newly developed for generation of high Mach number shock wave. Its characteristics was investigated for various operation parameters; such as a strength of the diaphragm at the end of the comparession tube, an initial pressure of low pressure tube, an initial pressure of medium pressure tube and the volume of compression tube. Under the restriction of fixed pressures for the driver high pressure tube (32×10^5Pa) and the low pressure tube (40Pa) in...

  14. Experimental verification of the quasi-steady approximation for aerodynamic sound generation by pulsating jets in tubes.

    Science.gov (United States)

    Zhang, Zhaoyan; Mongeau, Luc; Frankel, Steven H

    2002-10-01

    Voice production involves sound generation by a confined jet flow through an orifice (the glottis) with a time-varying area. Predictive models of speech production are usually based on the so-called quasi-steady approximation. The flow rate through the time-varying orifice is assumed to be the same as a sequence of steady flows through stationary orifices for wall geometries and flow boundary conditions that instantaneously match those of the dynamic, nonstationary problem. Either the flow rate or the pressure drop can then be used to calculate the radiated sound using conventional acoustic radiation models. The quasi-steady approximation allows complex unsteady flows to be modeled as steady flows, which is more cost effective. It has been verified for pulsating open jet flows. The quasi-steady approximation, however, has not yet been rigorously validated for the full range of flows encountered in voice production. To further investigate the range of validity of the quasi-steady approximation for voice production applications, a dynamic mechanical model of the larynx was designed and built. The model dimensions approximated those of human vocal folds. Airflow was supplied by a pressurized, quiet air storage facility and modulated by a driven rubber orifice. The acoustic pressure of waves radiated upstream and downstream of the orifice was measured, along with the orifice area and other time-averaged flow variables. Calculated and measured radiated acoustic pressures were compared. A good agreement was obtained over a range of operating frequencies, flow rates, and orifice shapes, confirming the validity of the quasi-steady approximation for a class of relevant pulsating jet flows.

  15. Steam generator issues in the United States

    Energy Technology Data Exchange (ETDEWEB)

    Strosnider, J.R. [NRC, Washington, DC (United States)

    1997-02-01

    Alloy 600 steam generator tubes in the US have exhibited degradation mechanisms similar to those observed in other countries. Effective programs have been implemented to address several degradation mechanisms including: wastage; mechanical wear; pitting; and fatigue. These degradation mechanisms are fairly well understood as indicated by the ability to effectively mitigate/manage them. Stress corrosion cracking (SCC) is the dominant degradation mechanism in the US. SCC poses significant inspection and management challenges to the industry and the regulators. The paper also addresses issues of research into SCC, inspection programs, plugging, repair strategies, water chemistry, and regulatory control. Emerging issues in the US include: parent tube cracking at sleeve joints; detection and repair of circumferential cracks; free span cracking; inspection and cracking of dented regions; and severe accident analysis.

  16. “People power” or “pester power”? YouTube as a forum for the generation of evidence and patient advocacy☆

    Science.gov (United States)

    Mazanderani, Fadhila; O’Neill, Braden; Powell, John

    2013-01-01

    Objective Venoplasty has been proposed, alongside the theory of chronic cerebrospinal venous insufficiency (CCSVI), as a treatment for multiple sclerosis (MS). Despite concerns about its efficacy and safety, thousands of patients have undergone the procedure. This paper analyses YouTube videos where patients have shared their treatment experiences. Methods Content analysis on the 100 most viewed videos from over 4000 identified in a search for ‘CCSVI’, and qualitative thematic analysis on popular ‘channels’ demonstrating patients’ experiences. Results Videos adopt an overwhelmingly positive stance towards CCSVI; many were uploaded by patients and present pre- and/or post-treatment experiences. Patients demonstrate rather than merely describe their symptoms, performing tests on themselves before and after treatment to quantify improvement. Videos combine medical terminology and tests with personal experiences of living with MS. Conclusion Social media technologies provide patients with novel opportunities for advocating for particular treatments; generating alternative forms of ‘evidence’ built on a hybrid of personal experience and medical knowledge. Practice implications Healthcare practitioners need to engage with new digital forms of content, including online social media. Instead of disregarding sources not considered ‘evidence-based’, practitioners should enhance their understanding of what ‘experiential-evidence’ is deemed significant to patients, particularly in contested areas of healthcare. PMID:23830239

  17. Dramatic enhancement of organics degradation and electricity generation via strengthening superoxide radical by using a novel 3D AQS/PPy-GF cathode.

    Science.gov (United States)

    Zhang, Yan; Li, Jinhua; Bai, Jing; Li, Linsen; Xia, Ligang; Chen, Shuai; Zhou, Baoxue

    2017-08-24

    A dramatic enhancement of organics degradation and electricity generation has been achieved in a wastewater fuel cell (WFC) system via strengthening superoxide radical with radical chain reaction by using a novel 3D anthraquinone/polypyrrole modified graphite felt (AQS/PPy-GF) cathode. The AQS/PPy-GF was synthesized by one-pot electrochemical polymerization method and used to in-situ generate superoxide radical by reducing oxygen under self-imposed electric field. Results showed that methyl orange (MO) were effectively degraded in AQS/PPy-GF/Fe(2+) system with a high apparent rate constant (0.0677 min(-1)), which was 3.9 times that (0.0174 min(-1)) in the Pt/Fe(2+) system and even 9.4 times that (0.0072 min(-1)) in the traditional WFC system (without Fe(2+)). Meanwhile, it showed a superior performance for electricity generation and the maximum power density output (1.130 mW cm(-2)) was nearly 3.3 times and 5.0 times higher, respectively, when compared with the Pt/Fe(2+) system and traditional WFC. This dramatic advance was attributed to 3D AQS/PPy-GF cathode which produces more O2(-) via one-electron reduction process. The presence of O2(-) cannot only directly contribute to MO degradation, but also promotes the final complete mineralization by turning itself to OH. Additionally, O2(-) accelerates the Fe(2+)/Fe(3+) couple cycling, thus avoiding continuous addition of any external ferrous ions. Inhibition and probe studies were conducted to ascertain the role of several radicals (OH and O2(-)) on the MO degradation. Superoxide radicals were considered as the primary reactive oxidants, and the degradation mechanism of MO was proposed. The proposed WFC system provides a more economical and efficient way for energy recovery and wastewater treatment. Copyright © 2017. Published by Elsevier Ltd.

  18. The Effect of Circular Finned Tube Heat Transfer Enhancement by Using Longitudinal Vortex Generators%纵向涡发生器对圆形翅片管换热强化的影响

    Institute of Scientific and Technical Information of China (English)

    于恩播; 孙铁; 张素香

    2012-01-01

    The fluid flow and heat transfer process of circular finned tube with longitudinal vortex generators(LVGs) were numerically simulated with the CFD calculation software FLUENT, then compared with the normal circular finned tube. The simulation results show that the performance of circular finned tube with longitudinal vortex generators is far better than that of the normal circular finned tube. It can be explained from the view point of field synergy principle, which says that the longitudinal vortex generators can enhance effect of heat transfer because it reduces the angle between velocity and fluid temperature gradient.%利用CFD计算软件FLUENT对带有纵向涡发生器的圆形翅片管的流体流动和传热过程进行数值模拟,并与普通圆形翅片管加以对比.结果表明,带有纵向涡发生器的翅片管换热效果明显优于普通翅片管.应用场协同原理解释认为,纵向涡发生器使流体速度和温度梯度之间夹角减小,改善了速度场和温度场的协同性,从而增强了换热效果.

  19. Computation of a leakage in a stream generator heating tube with realistic initial and boundary conditions; Berechnung eines Dampferzeugerheizrohrlecks mit realistischen Anfangs- und Randbedingungen

    Energy Technology Data Exchange (ETDEWEB)

    Sarkadi, Peter; Schaffrath, Andreas [TUEV NORD SysTec GmbH und Co. KG, Hamburg (Germany)

    2009-02-15

    Within the framework of the safety review of a pressurized water reactor, TUeV NORD SysTec GmbH and Co.KG analyzed plant behavior for the case of a leakage in a steam generator heating tube by means of the ATHLET thermohydraulic code system using realistic initial and boundary conditions. The analysis was performed to show that operation of the safety injection pumps avoids 2 out of 3 emergency cooling criteria being triggered. After coolant transfer from the primary to the secondary side, activity retention is ensured only if the coolant is contained by the components of the secondary system. This requires the pressure in the failed steam generator to remain below the level of 88.3 bar at which the safety valves respond. Startup of the safety injection pumps would jeopardize activity retention because of the zero head of these pumps. Analysis indicated the filling level of the pressurizer to be above 3.6 m during the accident. The minimum margin from the ''pressurizer level <2.28 m'' reactor protection limit is around 1.3 m. Consequently, only the first of the 3 emergency cooling criteria (in this case, 'coolant pressure <132 bar') will respond. This avoids unwanted boosting of the coolant pressure due to connection of the safety injection pumps. By the end of the period of observation, approx. 36 Mg of coolant are transferred to the secondary side. Activity retention is ensured by the components of the secondary system. (orig.)

  20. Hollow-Cathode Source Generates Plasma

    Science.gov (United States)

    Deininger, W. D.; Aston, G.; Pless, L. C.

    1989-01-01

    Device generates argon, krypton, or xenon plasma via thermionic emission and electrical discharge within hollow cathode and ejects plasma into surrounding vacuum. Goes from cold start up to full operation in less than 5 s after initial application of power. Exposed to moist air between operations without significant degradation of starting and running characteristics. Plasma generated by electrical discharge in cathode barrel sustained and aided by thermionic emission from emitter tube. Emitter tube does not depend on rare-earth oxides, making it vulnerable to contamination by exposure to atmosphere. Device modified for use as source of plasma in laboratory experiments or industrial processes.

  1. Gastrostomy Tube (G-Tube)

    Science.gov (United States)

    ... the recovery room, sometimes called the "post-op" (post-operative) room or PACU (post-anesthesia care unit), and ... site; discharge that's yellow, green, or foul-smelling; fever) excessive bleeding or drainage from the tube site ...

  2. Microbial community structure in a dual chamber microbial fuel cell fed with brewery waste for azo dye degradation and electricity generation.

    Science.gov (United States)

    Miran, Waheed; Nawaz, Mohsin; Kadam, Avinash; Shin, Seolhye; Heo, Jun; Jang, Jiseon; Lee, Dae Sung

    2015-09-01

    The expansion in knowledge of the microbial community structure can play a vital role in the electrochemical features and operation of microbial fuel cells (MFCs). In this study, bacterial community composition in a dual chamber MFC fed with brewery waste was investigated for simultaneous electricity generation and azo dye degradation. A stable voltage was generated with a maximum power density of 305 and 269 mW m(-2) for brewery waste alone (2000 mg L(-1)) and after the azo dye (200 mg L(-1)) addition, respectively. Azo dye degradation was confirmed by Fourier transform infrared spectroscopy (FT-IR) as peak corresponding to -N=N- (azo) bond disappeared in the dye metabolites. Microbial communities attached to the anode were analyzed by high-throughput 454 pyrosequencing of the 16S rRNA gene. Microbial community composition analysis revealed that Proteobacteria (67.3 %), Betaproteobacteria (30.8 %), and Desulfovibrio (18.3 %) were the most dominant communities at phylum, class, and genus level, respectively. Among the classified genera, Desulfovibrio most likely plays a major role in electron transfer to the anode since its outer membrane contains c-type cytochromes. At the genus level, 62.3 % of all sequences belonged to the unclassified category indicating a high level of diversity of microbial groups in MFCs fed with brewery waste and azo dye. • Azo dye degradation and stable bioelectricity generation was achieved in the MFC. • Anodic biofilm was analyzed by high-throughput pyrosequencing of the 16S rRNA gene. • Desulfovibrio (18.3 %) was the dominant genus in the classified genera. • Of the genus, 62.3 % were unclassified, thereby indicating highly diverse microbes. Graphical Abstract A schematic diagram of a dual chamber microbial fuel cell for azo dye degradation and current generation (with microbial communities at anode electrode).

  3. Design of a Metal Oxide-Organic Framework (MoOF) Foam Microreactor: Solar-Induced Direct Pollutant Degradation and Hydrogen Generation.

    Science.gov (United States)

    Zhu, Liangliang; Fu Tan, Chuan; Gao, Minmin; Ho, Ghim Wei

    2015-12-16

    A macroporous carbon network combined with mesoporous catalyst immobilization by a template method gives a metal-oxide-organic framework (MoOF) foam microreactor that readily soaks up pollutants and localizes solar energy in itself, leading to effective degradation of water pollutants (e.g., methyl orange (MO) and also hydrogen generation. The cleaned-up water can be removed from the microreactor simply by compression, and the microreactor used repeatedly.

  4. Thermomechanical Model and Bursting Tests to Evaluate the Risk of Swelling and Bursting of Modified 9Cr-1Mo Steel Steam Generator Tubes during a Sodium-Water Reaction Accident

    Directory of Open Access Journals (Sweden)

    C. Bertrand

    2014-01-01

    Full Text Available The MECTUB code was developed to evaluate the risk of swelling and bursting of Steam Generator (SG tubes. This code deals with the physic of intermediate steam-water leaks into sodium which induce a Sodium-Water Reaction (SWR. It is based on a one-dimensional calculation to describe the thermomechanical behavior of tubes under a high internal pressure and a fast external overheating. The mechanical model of MECTUB is strongly correlated with the kind of the material of the SG tubes. It has been developed and validated by using experiments performed on the alloy 800. A change to tubes made of Modified 9Cr-1Mo steel requires more knowledge of Modified 9Cr-1Mo steel behavior which influences the bursting time at high temperatures (up to 1200°C. Studies have been initiated to adapt the mechanical model and to qualify it for this material. The first part of this paper focuses on the mechanical law modelling (elasticity, plasticity, and creep for Modified 9Cr-1Mo steel and on overheating thermal data. In a second part, the results of bursting tests performed on Modified 9Cr-1Mo tubes in the SQUAT facility of CEA are used to validate the mechanical model of MECTUB for the Modified 9Cr-1Mo material.

  5. RPV steam generator pressure boundary

    Energy Technology Data Exchange (ETDEWEB)

    Strosnider, J.

    1996-03-01

    As the types of SG tube degradation affecting PWR SGs has changed, and improvements in tube inspection and repair technology have occurred, current SG regulatory requirements and guidance have become increasingly out of date. This regulatory situation has been dealt with on a plant-specific basis, however to resolve this problem in the long term, the NRC has begun development of a performance-based rule. As currently structured, the proposed steam generator rule would require licensees to implement SG programs that monitor the condition of the steam generator tubes against accepted performance criteria to provide reasonable assurance that the steam generator tubes remain capable of performing their intended safety functions. Currently the staff is developing three performance criteria that will ensure the tubes can continue to perform their safety function and therefore satisfy the SG rule requirements. The staff, in developing the criteria, is striving to ensure that the performance criteria have the two key attributes of being (1) measurable (enabling the tube condition to be {open_quotes}measured{close_quotes} against the criteria) and (2) tolerable (ensuring that failures to meet the criteria do not result in unacceptable consequences). A general description of the criteria are: (1) Structural integrity criteria: Ensures that the structural integrity of the SG tubes is maintained for the operating cycle consistent with the margins intended by the ASME Code. (2) Leakage integrity criteria: Ensures that postulated accident leakages and the associated dose releases are limited relative to 10 CFR Part 50 guidelines and 10 CFR Part 50 Appendix A GDC 19. (3) Operational leakage criteria: Ensures that the operating unit will be shut down as a defense-in depth measure when operational SG tube leakage exceeds established leakage limits.

  6. Determination and toxicity evaluation of the generated products in sulfamethoxazole degradation by UV/CoFe{sub 2}O{sub 4}/TiO{sub 2}

    Energy Technology Data Exchange (ETDEWEB)

    Gong, Han; Chu, Wei, E-mail: wei.chu@polyu.edu.hk

    2016-08-15

    Highlights: • Four pathways were determined in sulfamethoxazole degradation by UV/CoFe{sub 2}O{sub 4}/TiO{sub 2}. • Four intermediates were newly detected during sulfamethoxazole degradation. • Planktons were used in the toxicity evaluation of generated intermediates. • The toxicity of sulfanilamide as a harmful intermediate was studied. - Abstract: The photodegradation of sulfamethoxazole (SMX) under UV radiation with a recyclable catalyst CoFe{sub 2}O{sub 4}/TiO{sub 2} was examined. The reaction mechanism during the treatment was determined. The toxicity of the degradation intermediates to aquatic organisms, including the green alga Chlorella vulgaris and the brine shrimp Artemia salina was investigated. SMX was completely removed and about 50% TOC was degraded in 5 h. Sixteen intermediates were detected, from which four of them were reported for the first time in this study. Four main decay pathways, i.e., hydroxylation, cleavage of S−N bond, nitration of amino group, and isomerization were proposed. About 45% of the total mass sulfur source transformed to sulfate ion, and around 25%, 1%, and 0.25% of the total nitrogen transformed to ammonium, nitrogen, and nitrite ions. The toxicity of the treated solution was significantly reduced compared to that of the parent compound SMX. A variation of the algae growth was observed, which was due to the combination of generation of toxic intermediates (i.e., sulfanilamide) and the release of inorganic substances and carbon source as additional nutrients. The adverse effect on the clearance rate of the brine shrimp was also observed, but it can be eliminated if longer degradation time is used.

  7. Development of a light weighted mobile robot for SG tube inspection in NPP

    Energy Technology Data Exchange (ETDEWEB)

    Seo, Yong Chil; Jeong, Kyung Min; Shin, Hochul; Gweng, Jung Ju; Lee, Sung Uk; Jeong, Seung Ho; Choi, Young Soo; Kim, Seung Ho [KAERI, Daejeon (Korea, Republic of); Shin, Chun Sup; Park, Ki Tae [Korea Plant Service and Engineering, Busan (Korea, Republic of)

    2012-10-15

    Steam generators (SG) are among the most critical components of pressurized water Nuclear Power Plants (NPP). SG tubes must provide a reliable pressure boundary between the primary and secondary cooling water, because any leakage from tube defects could result in the release of radioactivity to the environment. Thus degradations of steam generators tubes should be monitored and inspected periodically under nuclear regulation. In service inspections of SG tubes are carried out using eddy current test (ECT) and the defected tubes are usually plugged. Because the radioactivity in the internal SG chambers limits free access of human workers, remote manipulators are required. In South Korea, Manipulators such as the Zet ec SM series and the Westinghouse ROSA series have bee used. Such manipulators are rigidly mounted to man ways or tube sheets of SG. Confusions of the inspected tubes may occur from deflection of the manipulators. To reduce the deflections of the manipulators for covering the large working areas of tube sheets, sufficient rigidity is required and that leads to an increase of the weight. Such weight increase results in some difficulties for handling and more radiation exposure of human workers. Recently light weighed mobile robots have been introduced by Westinghouse and Zet ec. The robots can move keeping in contact with the tube sheets using devices which are commonly called cam locks. They are easier to handle and provide no confusion for the position of the inspected tubes. But when the clamping forces are loosed accidentally, they can be fall down and light repair works can be performed. This paper provides the design results for a lightweight mobile robot which is being developed in cooperation of our institutes.

  8. Structural Safety Analysis on Tube Sheet With Deviated Holes in Steam Generator%蒸汽发生器管板孔桥超差情况下的结构安全性分析

    Institute of Scientific and Technical Information of China (English)

    李海龙; 王庆; 徐宇; 熊冬庆; 王臣; 张跃

    2014-01-01

    蒸汽发生器制造过程中对管板进行深孔钻时,发生管板孔桥超差。管板二次侧的3个管孔C165‐R59、C167‐R59、C168‐R58不能满足设计要求,管板一次侧的这些管孔满足设计要求。针对该不符合项,核审评单位联合蒸汽发生器制造单位和设计单位,从管板的强度、管板孔桥超差不符合项对流致振动的影响、堵管后的传热管应力分析、传热管堵管的压差对孔桥强度的影响、孔桥超差导致的传热管接触磨损等角度进行了结构安全性分析。分析结果表明,目前的堵管方案合理可行,但需加强在役阶段的跟踪检查,以保证修复的可靠性和质量。%During the manufacturing process of the steam generator ,deviated holes were detected w hen drilling the tube sheet . T he sizes of three holes including C165‐R59 , C167‐R59 and C168‐R58 on the secondary side of the tube sheet don’t meet the design requirements ,while the sizes and positions of those holes on the primary side are within design requirements . The structural safety analyses ,including tube sheet strength , influence of tube sheet with deviated holes on flow induced vibration (FIV ) , stress analysis of plugged tubes ,influence of the differential pressure between the plugged tubes and the unplugged tubes on the strength ,and fretting wear between tubes caused by deviated holes ,were done by the nuclear safety reviewer combined with the manufac‐turer and the designer .T he results show that the repair plan is reasonable and feasibili‐ty .Meanwhile ,in‐service follow‐up inspections must be strengthened to insure the quality and reliability of plugged tubes .

  9. Phenomena identification and ranking tables for Westinghouse AP600 small break loss-of-coolant accident, main steam line break, and steam generator tube rupture scenarios

    Energy Technology Data Exchange (ETDEWEB)

    Wilson, G.E.; Fletcher, C.D.; Davis, C.B. [and others

    1997-06-01

    This report revision incorporates new experimental evidence regarding AP600 behavior during small break loss-of-coolant accidents. This report documents the results of Phenomena Identification and Ranking Table (PIRT) efforts for the Westinghouse AP600 reactor. The purpose of this PIRT is to identify important phenomena so that they may be addressed in both the experimental programs and the RELAP5/MOD3 systems analysis computer code. In Revision of this report, the responses of AP600 during small break loss-of-coolant accident, main steam line break, and steam generator tube rupture accident scenarios were evaluated by a committee of thermal-hydraulic experts. Committee membership included Idaho National Engineering and Environmental Laboratory staff and recognized thermal-hydraulic experts from outside of the laboratory. Each of the accident scenarios was subdivided into separate, sequential periods or phases. Within each phase, the plant behavior is controlled by, at most, a few thermal-hydraulic processes. The committee identified the phenomena influencing those processes, and ranked & influences as being of high, medium, low, or insignificant importance. The primary product of this effort is a series of tables, one for each phase of each accident scenario, describing the thermal-hydraulic phenomena judged by the committee to be important, and the relative ranking of that importance. The rationales for the phenomena selected and their rankings are provided. This document issue incorporates an update of the small break loss-of-coolant accident portion of the report. This revision is the result of the release of experimental evidence from AP600-related integral test facilities (ROSA/AP600, OSU, and SPES) and thermal-hydraulic expert review. The activities associated with this update were performed during the period from June 1995 through November 1996. 8 refs., 26 figs., 42 tabs.

  10. 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.

  11. Rational design of hyperbranched 3D heteroarrays of SrS/CdS: synthesis, characterization and evaluation of photocatalytic properties for efficient hydrogen generation and organic dye degradation.

    Science.gov (United States)

    Khan, Ziyauddin; Chetia, Tridip Ranjan; Qureshi, Mohammad

    2012-06-07

    Hyperbranched 3D SrS/CdS nanostructures were synthesized using a one pot hydrothermal method. Transmission Electron Microscopy (TEM) and Field Emission-Scanning Electron Microscopy (FE-SEM) analysis showed the formation of flower-like structure and the crystalline phase was confirmed by powder X-ray diffraction. The prepared 3D SrS/CdS exhibited improved photocatalytic activity for water splitting leading to H(2) generation (AQY 10%) and nearly complete degradation of methyl orange (MO) dye. The dye degradation followed first order kinetics and the apparent reaction rate constant (k(app)) was 0.136 min(-1). The present 3D SrS/CdS structure promise to be efficient photocatalysts due to (i) the facile intersystem charge transfer resulting from their band alignment (ii) enhanced specific surface area and (iii) crystallinity.

  12. In vitro degradation and total gas production of byproducts generated in the biodiesel production chain

    OpenAIRE

    2015-01-01

    This study aimed to evaluate the in vitro degradation and total gas production of different oil seed press cakes from a biodiesel production chain gas through the use of a semi-automatic technique of gas production in vitro. The treatments consisted of substituting elephant grass in increasing levels, 0%, 30, 50 and 70%, with the byproducts of Gossyypium hirsutum, Ricinus communis, Moringa oleifeira, Jatropha curcas and Helianthus annus. The oil seed press cakes of Moringa oleifeira had the h...

  13. Nanostructured CdS sensitized CdWO4 nanorods for hydrogen generation from hydrogen sulfide and dye degradation under sunlight.

    Science.gov (United States)

    Sethi, Yogesh A; Panmand, Rajendra P; Kadam, Sunil R; Kulkarni, Aniruddha K; Apte, Sanjay K; Naik, Sonali D; Munirathnam, N; Kulkarni, Milind V; Kale, Bharat B

    2017-02-01

    In this report, CdS nanoparticles have been grown on the surface of CdWO4 nanorods via an in-situ approach and their high photocatalytic ability toward dye degradation and H2 evolution from H2S splitting under visible light has been demonstrated. The structural and optical properties as well as morphologies with varying amount of CdS to form CdS@CdWO4 have been investigated. Elemental mapping and high resolution transmission electron microscopy (HRTEM) analysis proved the sensitization of CdWO4 nanorods by CdS nanoparticles. A decrease in the PL emission of CdWO4 was observed with increasing amount of CdS nanoparticles loading possibly due to the formation of trap states. Considering the band gap in visible region, the photocatalytic study has been performed for H2 production from H2S and dye degradation under natural sunlight. The steady evolution of H2 was observed from an aqueous H2S solution even without noble metal. Moreover, the rate of photocatalytic H2 evolution over CdS modified CdWO4 is ca. 5.6 times higher than that of sole CdWO4 under visible light. CdS modified CdWO4 showed a good ability toward the photo-degradation of methylene Blue. The rate of dye degradation over CdS modified CdWO4 is ca. 7.4 times higher than that of pristine CdWO4 under natural sunlight. With increase in amount of CdS nanoparticle loading on CdWO4 nanorods the hydrogen generation was observed to be decreased where as dye degradation rate is increased. Such nano-heterostructures may have potential in other photocatalytic reactions. Copyright © 2016. Published by Elsevier Inc.

  14. Use of self-organizing maps for classification of defects in the tubes from the steam generator of nuclear power plants; Classificacao de defeitos em tubos de gerador de vapor de plantas nucleares utilizando mapas auto-organizaveis

    Energy Technology Data Exchange (ETDEWEB)

    Mesquita, Roberto Navarro de

    2002-07-01

    This thesis obtains a new classification method for different steam generator tube defects in nuclear power plants using Eddy Current Test signals. The method uses self-organizing maps to compare different signal characteristics efficiency to identify and classify these defects. A multiple inference system is proposed which composes the different extracted characteristic trained maps classification to infer the final defect type. The feature extraction methods used are the Wavelet zero-crossings representation, the linear predictive coding (LPC), and other basic signal representations on time like module and phase. Many characteristic vectors are obtained with combinations of these extracted characteristics. These vectors are tested to classify the defects and the best ones are applied to the multiple inference system. A systematic study of pre-processing, calibration and analysis methods for the steam generator tube defect signals in nuclear power plants is done. The method efficiency is demonstrated and characteristic maps with the main prototypes are obtained for each steam generator tube defect type. (author)

  15. myo-Inositol phosphate isomers generated by the action of a phytate-degrading enzyme from Klebsiella terrigena on phytate.

    Science.gov (United States)

    Greiner, Ralf; Carlsson, Nils-Gunnar

    2006-08-01

    For the first time a dual pathway for dephosphorylation of myo-inositol hexakisphosphate by a histidine acid phytase was established. The phytate-degrading enzyme of Klebsiella terrigena degrades myo-inositol hexakisphosphate by stepwise dephosphorylation, preferably via D-Ins(1,2,4,5,6)P5, D-Ins(1,2,5,6)P4, D-Ins(1,2,6)P3, D-Ins(1,2)P2 and alternatively via D-Ins(1,2,4,5,6)P5, Ins(2,4,5,6)P4, D-Ins(2,4,5)P3, D-Ins(2,4)P2 to finally Ins(2)P. It was estimated that more than 98% of phytate hydrolysis occurs via D-Ins(1,2,4,5,6)P5. Therefore, the phytate-degrading enzyme from K. terrigena has to be considered a 3-phytase (EC 3.1.3.8). A second dual pathway of minor importance could be proposed that is in accordance with the results obtained by analysis of the dephosphorylation products formed by the action of the phytate-degrading enzyme of K. terrigena on myo-inositol hexakisphosphate. It proceeds preferably via D-Ins(1,2,3,5,6)P5, D-Ins(1,2,3,6)P4, Ins(1,2,3)P3, D-Ins(2,3)P2 and alternatively via D-Ins(1,2,3,5,6)P5, D-Ins(2,3,5,6)P4, D-Ins(2,3,5)P3, D-Ins(2,3)P2 to finally Ins(2)P. D-Ins(2,3,5,6)P4, D-Ins(2,3,5)P3, and D-Ins(2,4)P2 were reported for the first time as intermediates of enzymatic phytate dephosphorylation. A role of the phytate-degrading enzyme from K. terrigena in phytate breakdown could not be ruled out. Because of its cytoplasmatic localization and the suggestions for substrate recognition, D-Ins(1,3,4,5,6)P5 might be the natural substrate of this enzyme and, therefore, may play a role in microbial pathogenesis or cellular myo-inositol phosphate metabolism.

  16. Protective Effects of N-Acetyl Cysteine against Diesel Exhaust Particles-Induced Intracellular ROS Generates Pro-Inflammatory Cytokines to Mediate the Vascular Permeability of Capillary-Like Endothelial Tubes.

    Directory of Open Access Journals (Sweden)

    Chia-Yi Tseng

    Full Text Available Exposure to diesel exhaust particles (DEP is associated with pulmonary and cardiovascular diseases. Previous studies using in vitro endothelial tubes as a simplified model of capillaries have found that DEP-induced ROS increase vascular permeability with rearrangement or internalization of adherens junctional VE-cadherin away from the plasma membrane. This allows DEPs to penetrate into the cell and capillary lumen. In addition, pro-inflammatory cytokines are up-regulated and mediate vascular permeability in response to DEP. However, the mechanisms through which these DEP-induced pro-inflammatory cytokines increase vascular permeability remain unknown. Hence, we examined the ability of DEP to induce permeability of human umbilical vein endothelial cell tube cells to investigate these mechanisms. Furthermore, supplementation with NAC reduces ROS production following exposure to DEP. HUVEC tube cells contributed to a pro-inflammatory response to DEP-induced intracellular ROS generation. Endothelial oxidative stress induced the release of TNF-α and IL-6 from tube cells, subsequently stimulating the secretion of VEGF-A independent of HO-1. Our data suggests that DEP-induced intracellular ROS and release of the pro-inflammatory cytokines TNF- α and IL-6, which would contribute to VEGF-A secretion and disrupt cell-cell borders and increase vasculature permeability. Addition of NAC suppresses DEP-induced ROS efficiently and reduces subsequent damages by increasing endogenous glutathione.

  17. Phosphate Shifted Oxygen Reduction Pathway on Fe@Fe2O3 Core-Shell Nanowires for Enhanced Reactive Oxygen Species Generation and Aerobic 4-Chlorophenol Degradation.

    Science.gov (United States)

    Mu, Yi; Ai, Zhihui; Zhang, Lizhi

    2017-07-18

    Phosphate ions widely exist in the environment. Previous studies revealed that the adsorption of phosphate ions on nanoscale zerovalent iron would generate a passivating oxide shell to block reactive sites and thus decrease the direct pollutant reduction reactivity of zerovalent iron. Given that molecular oxygen activation process is different from direct pollutant reduction with nanoscale zerovalent iron, it is still unclear how phosphate ions will affect molecular oxygen activation and reactive oxygen species generation with nanoscale zerovalent iron. In this study, we systematically studied the effect of phosphate ions on molecular oxygen activation with Fe@Fe2O3 nanowires, a special nanoscale zerovalent iron, taking advantages of rotating ring disk electrochemical analysis. It was interesting to find that the oxygen reduction pathway on Fe@Fe2O3 nanowires was gradually shifted from a four-electron reduction pathway to a sequential one-electron reduction one, along with increasing the phosphate ions concentration from 0 to 10 mmol·L(-1). This oxygen reduction pathway change greatly enhanced the molecular oxygen activation and reactive oxygen species generation performances of Fe@Fe2O3 nanowires, and thus increased their aerobic 4-chlorophenol degradation rate by 10 times. These findings shed insight into the possible roles of widely existed phosphate ions in molecular oxygen activation and organic pollutants degradation with nanoscale zerovalent iron.

  18. Chest tube insertion

    Science.gov (United States)

    ... tube insertion; Insertion of tube into chest; Tube thoracostomy; Pericardial drain ... Kirsch TD, Sax J. Tube thoracostomy. In: Roberts JR, ed. Roberts and ... . 6th ed. Philadelphia, PA: Elsevier Saunders; 2014:chap 10.

  19. Jejunostomy feeding tube

    Science.gov (United States)

    ... page: //medlineplus.gov/ency/patientinstructions/000181.htm Jejunostomy feeding tube To use the sharing features on this ... vomiting Your child's stomach is bloated Alternate Names Feeding - jejunostomy tube; G-J tube; J-tube; Jejunum ...

  20. EXPERIMENTAL INVESTIGATION OF NICKEL ALUMINIDE (NI3AL) NANOSTRUCTURED COATED ECONOMISER TUBE IN BOILER

    OpenAIRE

    * Gokulakannan A, Karuppasamy K

    2016-01-01

    Thermal Power Stations all over the world are facing the problem of boiler tube leakage frequently. The consequences of which affects the performance of power plant and huge amount of money loss. Hot corrosion and erosion are recognized as serious problems in coal based power generation plants in India. The maximum number of cause of failure in economizer unit is due to flue gas erosion. The corrosion resistant coatings used conventionally are having some limitations like degradation of the c...

  1. Infrared imaging of LED lighting tubes and fluorescent tubes

    Science.gov (United States)

    Siikanen, Sami; Kivi, Sini; Kauppinen, Timo; Juuti, Mikko

    2011-05-01

    The low energy efficiency of conventional light sources is mainly caused by generation of waste heat. We used infrared (IR) imaging in order to monitor the heating of both LED tube luminaires and ordinary T8 fluorescent tubes. The IR images showed clearly how the surface temperatures of the fluorescent tube ends quickly rose up to about +50...+70°C, whereas the highest surface temperatures seen on the LED tubes were only about +30...+40°C. The IR images demonstrated how the heat produced by the individual LED chips can be efficiently guided to the supporting structure in order to keep the LED emitters cool and hence maintain efficient operation. The consumed electrical power and produced illuminance were also recorded during 24 hour measurements. In order to assess the total luminous efficacy of the luminaires, separate luminous flux measurements were made in a large integrating sphere. The currently available LED tubes showed efficacies of up to 88 lm/W, whereas a standard "cool white" T8 fluorescent tube produced ca. 75 lm/W. Both lamp types gave ca. 110 - 130 lx right below the ceiling-mounted luminaire, but the LED tubes consume only 40 - 55% of the electric power compared to fluorescent tubes.

  2. Determination and toxicity evaluation of the generated products in sulfamethoxazole degradation by UV/CoFe2O4/TiO2.

    Science.gov (United States)

    Gong, Han; Chu, Wei

    2016-08-15

    The photodegradation of sulfamethoxazole (SMX) under UV radiation with a recyclable catalyst CoFe2O4/TiO2 was examined. The reaction mechanism during the treatment was determined. The toxicity of the degradation intermediates to aquatic organisms, including the green alga Chlorella vulgaris and the brine shrimp Artemia salina was investigated. SMX was completely removed and about 50% TOC was degraded in 5h. Sixteen intermediates were detected, from which four of them were reported for the first time in this study. Four main decay pathways, i.e., hydroxylation, cleavage of SN bond, nitration of amino group, and isomerization were proposed. About 45% of the total mass sulfur source transformed to sulfate ion, and around 25%, 1%, and 0.25% of the total nitrogen transformed to ammonium, nitrogen, and nitrite ions. The toxicity of the treated solution was significantly reduced compared to that of the parent compound SMX. A variation of the algae growth was observed, which was due to the combination of generation of toxic intermediates (i.e., sulfanilamide) and the release of inorganic substances and carbon source as additional nutrients. The adverse effect on the clearance rate of the brine shrimp was also observed, but it can be eliminated if longer degradation time is used.

  3. A computational model for reliability calculation of steam generators from defects in its tubes; Um modelo computacional para o calculo da confiabilidade de geradores de vapor a partir de defeitos em seus tubos

    Energy Technology Data Exchange (ETDEWEB)

    Rivero, Paulo C.M.; Melo, P.F. Frutuoso e [Universidade Federal, Rio de Janeiro, RJ (Brazil). Coordenacao dos Programas de Pos-graduacao de Engenharia. Programa de Engenharia Nuclear

    2000-07-01

    Nowadays, probability approaches are employed for calculating the reliability of steam generators as a function of defects in their tubes without any deterministic association with warranty assurance. Unfortunately, probability models produce large failure values, as opposed to the recommendation of the U.S. Code of Federal Regulations, that is, failure probabilities must be as small as possible In this paper, we propose the association of the deterministic methodology with the probabilistic one. At first, the failure probability evaluation of steam generators follows a probabilistic methodology: to find the failure probability, critical cracks - obtained from Monte Carlo simulations - are limited to have length's in the interval defined by their lower value and the plugging limit one, so as to obtain a failure probability of at most 1%. The distribution employed for modeling the observed (measured) cracks considers the same interval. Any length outside the mentioned interval is not considered for the probability evaluation: it is approached by the deterministic model. The deterministic approach is to plug the tube when any anomalous crack is detected in it. Such a crack is an observed one placed in the third region on the plot of the logarithmic time derivative of crack lengths versus the mode I stress intensity factor, while for normal cracks the plugging of tubes occurs in the second region of that plot - if they are dangerous, of course, considering their random evolution. A methodology for identifying anomalous cracks is also presented. (author)

  4. The surface engineering of CdS nanocrystal for photocatalytic reaction: A strategy of modulating the trapping states and radicals generation towards RhB degradation

    Energy Technology Data Exchange (ETDEWEB)

    Li, Shuo, E-mail: lishuochem@outlook.com; Meng, Dedong, E-mail: 1159594702@qq.com; Hou, Libo, E-mail: hlb2014332156@outlook.com; Wang, Dejun, E-mail: wangdj@jlu.edu.cn; Xie, Tengfeng, E-mail: xietf@jlu.edu.cn

    2016-05-15

    Highlights: • Surfactants were successfully used for the surface states engineering of CdS nanocrystal. • The existence and the location of surface hole traps and surface electron traps were investigated. • The surface states can modulate the generation of radicals. - Abstract: Cationic surfactant (CTAB) and anionic surfactant (sodium oleate) were used to modify CdS nanocrystals with different surface states. The surfactant CTAB led to surface states of hole traps, while sodium oleate induced surface states of electron traps on the surface of CdS. The photodegradation of rhodamine B (RhB) over these modified CdS nanocrystals was investigated under visible light irradiation. An efficient cycloreversion degradation of RhB occurred over the E-CdS nanocrystals. However, for H-CdS nanocrystals, an efficient N-deethylation reaction concomitant with a subsequent slow cycloreversion reaction of RhB was observed. The E-CdS sample showed a first-order kinetic rate for the cycloreversion degradation of RhB. By contrast, H-CdS sample shows a zero-order kinetic rate for the N-deethylation reaction of RhB followed by a first-order kinetic rate for the cycloreversion degradation. It is revealed that the different kinds of surface traps could significantly affect the dynamic properties of photogenerated charge carriers, which leads to different degradation mechanism of RhB. These findings demonstrate an alternative solution towards developing efficient photocatalysts with high selectivity by constructing different surface trap states.

  5. Acoustical studies on corrugated tubes

    Science.gov (United States)

    Balaguru, Rajavel

    Corrugated tubes and pipes offer greater global flexibility combined with local rigidity. They are used in numerous engineering applications such as vacuum cleaner hosing, air conditioning systems of aircraft and automobiles, HVAC control systems of heating ducts in buildings, compact heat exchangers, medical equipment and offshore gas and oil transportation flexible riser pipelines. Recently there has been a renewed research interest in analyzing the flow through a corrugated tube to understand the underlying mechanism of so called whistling, although the whistling in such a tube was identified in early twentieth century. The phenomenon of whistling in a corrugated tube is interesting because an airflow through a smooth walled tube of similar dimensions will not generate any whistling tones. Study of whistling in corrugated tubes is important because, it not only causes an undesirable noise problem but also results in flow-acoustic coupling. Such a coupling can cause significant structural vibrations due to flow-acoustic-structure interaction. This interaction would cause flow-induced vibrations that could result in severe damage to mechanical systems having corrugated tubes. In this research work, sound generation (whistling) in corrugated tubes due to airflow is analyzed using experimental as well as Computational Fluid Dynamics-Large Eddy Simulation (CFD-LES) techniques. Sound generation mechanisms resulting in whistling have been investigated. The whistling in terms of frequencies and sound pressure levels for different flow velocities are studied. The analytical and experimental studies are carried out to understand the influence of various parameters of corrugated tubes such as cavity length, cavity width, cavity depth, pitch, Reynolds numbers and number of corrugations. The results indicate that there is a good agreement between theoretically calculated, computationally predicted and experimentally measured whistling frequencies and sound pressure levels

  6. The Functionality of Paratexts on YouTube

    DEFF Research Database (Denmark)

    Simonsen, Thomas Mosebo

    2014-01-01

    This chapter investigates paratexts and their functionality on YouTube. It is argued that YouTube content is in fact characterized by its dependence and usage of paratexts as part of YouTube's infrastructure. Paratexts are presented as being either auto-generated by YouTube or created by its user...

  7. A study of the effects of degraded imagery on tactical 3D model generation using structure-from-motion

    Science.gov (United States)

    Bolick, Leslie; Harguess, Josh

    2016-05-01

    An emerging technology in the realm of airborne intelligence, surveillance, and reconnaissance (ISR) systems is structure-from-motion (SfM), which enables the creation of three-dimensional (3D) point clouds and 3D models from two-dimensional (2D) imagery. There are several existing tools, such as VisualSFM and open source project OpenSfM, to assist in this process, however, it is well-known that pristine imagery is usually required to create meaningful 3D data from the imagery. In military applications, such as the use of unmanned aerial vehicles (UAV) for surveillance operations, imagery is rarely pristine. Therefore, we present an analysis of structure-from-motion packages on imagery that has been degraded in a controlled manner.

  8. Land-Use Planning in the Chaco Plain (Burruyacú, Argentina): Part 2: Generating a Consensus Plan to Mitigate Land-Use Conflicts and Minimize Land Degradation

    Science.gov (United States)

    Recatalá Boix, Luis; Zinck, Joseph Alfred

    2008-08-01

    The Burruyacú district (Tucumán province, Northwest Argentina) has been traditionally an area with rural activities based on the exploitation of the Chaco forest for timber and livestock browsing. Since the 1960s, local institutions started promoting soybean due to favorable land conditions and good market prices. Soybean extension, as from the 1970s, has resulted in important reduction of the Chaco forest and also caused physical soil degradation, especially soil compaction and erosion. A land-use-planning exercise was carried out using the Land-Use Planning and Information System (LUPIS) as a spatial decision support system. LUPIS facilitates the generation of alternative land-use plans by adjusting the relative importance attributed by multiple stakeholders to preference and avoidance policies. The system leads to the allocation of competing land uses to land map units in accordance with their preferred resource requirements, conditional upon the resource base of the area and the stakeholders’ demands. After generating a land use plan for each stakeholder category identified in the study area, including commercial farmers, conservative/conventional farmers, and conservationists, a consensus plan was established to address the land-use conflicts between mechanized agriculture, traditional agriculture and forest conservation, and to mitigate soil degradation caused by extensive dry-farming. Although the planning exercise did not directly involve the stakeholders, the results are sufficiently practical and realistic to suggest that the approach could be extended to the entire Chaco plain region.

  9. Broadcast yourself on YouTube - really?

    NARCIS (Netherlands)

    Kruitbosch, G.; Nack, F.

    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

  10. Broadcast yourself on YouTube - really?

    NARCIS (Netherlands)

    Kruitbosch, G.; Nack, F.

    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

  11. Effect of tube-support interaction on the dynamic responses of heat exchanger tubes. [LMFBR

    Energy Technology Data Exchange (ETDEWEB)

    Shin, Y.S.; Jendrzejczyk, J.A.; Wambsganss, M.W.

    1977-01-01

    Operating heat exchangers have experienced tube damages due to excessive flow-induced vibration. The relatively small inherent tube-to-baffle hole clearances associated with manufacturing tolerances in heat exchangers affect the tube vibrational characteristics. In attempting a theoretical analysis, questions arise as to the effects of tube-baffle impacting on dynamic responses. Experiments were performed to determine the effects of tube-baffle impacting in vertical/horizontal tube orientation, and in air/water medium on the vibrational characteristics (resonant frequencies, mode shapes, and damping) and displacement response amplitudes of a seven-span tube model. The tube and support conditions were prototypic, and overall length approximately one-third that of a straight tube segment of the steam generator designed for the CRBR. The test results were compared with the analytical results based on the multispan beam with ''knife-edge'' supports.

  12. 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.

  13. 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.

  14. Modelling the flow and the two-phase science of heat inside a cross-section tube of a `once through` vapor generator overheated with sodium; Modelisation de l`ecoulement et de la thermique double phase a l`interieur d`un tube droit de generateur de vapeur `once-through` a surchauffe chauffe au sodium

    Energy Technology Data Exchange (ETDEWEB)

    Mutelle, H

    1997-11-28

    Concerning the future fast neutrons reactors, studied in the frame of the European Fast Reactor (E.F.R.) project, several innovations have been proposed particularly in the field of vapor generators. These vapor generators have the particularity to use two different exchange fluids which can react violently one with the other. The thermodynamic fluid or secondary fluid is water under high pressure (18.5 MPa) which comes under saturated in the inlet of the device, warms and vaporizes inside the nest of boiler-tubes. At the outlet, vapor is overheated. The primary fluid is a liquid metal (sodium for French reactors) which flows outside the nest of boiler-tubes in the opposite direction of the secondary fluid. Several vapor generators models have been carried out. Concerning the European Fast Reactor project, the tubes have a cross-section and are in ferritic steel. Inside the boiler-tubes, the water-vapor flow can be divided into three areas. The first one is the liquid monophasic rate. It ends by the start of the boiling which is nucleated in the shell. Downstream, the two-phase flow passes from a bubbles flow to an annular flow. The liquid is then on the form of shell film and on the form of droplets carried along by the vapor flux. The dryout of the annular film is the start of the third area where there is vapor forced convection. At the present time, there is still no thermohydraulic code in the conditions of the E.F.R. vapor generator. In order to have a reliable size tool, the members of the E.F.R. project have then decided to do a two-phase flow model and have experimented a mono tubular scale model called ``ATLAS`` which represents well the real component for size, fluids and running conditions. The aim of the present work is then, in the frame of this experimental program, to 1)qualify the heat exchange and friction laws which will be later introduced in the thermohydraulic codes of cross-sections vapor generators 2)characterize the dryout phenomenon 3

  15. “People power” or “pester power”? YouTube as a forum for the generation of evidence and patient advocacy ☆

    OpenAIRE

    Mazanderani, Fadhila; O'Neill, Braden; Powell, John

    2013-01-01

    Objective Venoplasty has been proposed, alongside the theory of chronic cerebrospinal venous insufficiency (CCSVI), as a treatment for multiple sclerosis (MS). Despite concerns about its efficacy and safety, thousands of patients have undergone the procedure. This paper analyses YouTube videos where patients have shared their treatment experiences. Methods Content analysis on the 100 most viewed videos from over 4000 identified in a search for ‘CCSVI’, and qualitative thematic analysis on pop...

  16. Electrosleeve process for in-situ nuclear steam generator repair

    Energy Technology Data Exchange (ETDEWEB)

    Barton, R.A. [Ontario Hydro Technologies, Toronto, ON (Canada); Moran, T.E. [Framatome Technologies Inc., Lynchburg, VA (United States); Renaud, E. [Babcock and Wilcox Industries Ltd., Cambridge, ON (Canada)

    1997-07-01

    Degradation of steam generator (SG) tubing by localized corrosion is a widespread problem in the nuclear industry that can lead to costly forced out-ages, unit de-rating, SG replacement or even the permanent shutdown of a reactor. In response to the onset of SG tubing degradation at Ontario Hydro's Pickering Nuclear Generating Station (PNGS) Unit 5, and the determined unsuitability of conventional repair methods (mechanically expanded or welded sleeves) for Alloy 400, an alternative repair technology was developed. Electrosleeve is a non-intrusive, low-temperature process that involves the electrodeposition of a nanocrystalline nickel microalloy forming a continuously bonded, structural layer over the internal diameter of the degraded region. This technology is designed to provide a long-term pressure boundary repair, fully restoring the structural integrity of the damaged region to its original state. This paper describes the Electrosleeve process for SG tubing repair and the unique properties of the advanced sleeve material. The successful installation of Electrosleeves that have been in service for more than three years in Alloy 400 SG tubing at the Pickering-5 CANDU unit, the more recent extension of the technology to Alloy 600 and its demonstration in a U.S. pressurized water reactor (PWR), is presented. A number of PWR operators have requested plant operating technical specification changes to permit Electrosleeve SG tube repair. Licensing of the Electrosleeve by the U.S. Nuclear Regulatory Commission (NRC) is expected imminently. (author)

  17. Efficacy of the Reactive Oxygen Species Generated by Immobilized TiO2 in the Photocatalytic Degradation of Diclofenac

    Directory of Open Access Journals (Sweden)

    B. Di Credico

    2015-01-01

    Full Text Available We report on the photodegradation of diclofenac (DCF by hydrothermal anatase nanocrystals either free or immobilized in porous silica matrix (TS in connection to the type and amount of reactive oxygen species (ROS, in order to have deeper insight into their role in the photocatalysis and to provide an effective tool to implement the DCF mineralization. TiO2 and TS exhibit a remarkable efficiency in the DCF abatement, supporting that the utilization of anatase nanoparticles with the highly reactive {001}, {010}, and {101} exposed surfaces can be an effective way for enhancing the photooxidation even of the persistent pollutants. Furthermore, the hydrothermal TiO2, when immobilized in silica matrix, preserves its functional properties, combining high photoactivity with an easy technical use and recovery of the catalyst. The catalysts performances have been related to the presence of OH•, O21, and O2-• species by electron paramagnetic resonance spin-trap technique. The results demonstrated that the ROS concentration increases with the increase of photoactivity and indicated a significant involvement of O21 in the DCF degradation. The efficacy of TiO2 when immobilized on a silica matrix was associated with the high ROS life time and with the presence of singlet oxygen, which contributes to the complete photomineralization of DCF.

  18. A Conceptual Design of Light-weighted Mobile Robot for the Integrity of SG Tubes in NPP

    Energy Technology Data Exchange (ETDEWEB)

    Seo, Yong Chil; Jeong, Kyung Min; Shin, Ho Chul; Lee, Sung Uk; Cho, Jae Wan; Choi, Young Soo; Kim, Seung Ho [Korea Atomic Energy Research Institute, Daejeon (Korea, Republic of); Shin, Chun Sup; Park, Ki Tae [Korea Plant Serviceand Engineering, Busan (Korea, Republic of)

    2010-10-15

    Steam generators (SG) are among the most critical components of pressurized water Nuclear Power Plants (NPP). SG tubes must provide a reliable pressure boundary between the primary and secondary cooling water. It is because that any leakage from tube defects could result in the release of radioactivity to the environment. Thus degradations of steam generators tubes should be monitored and inspected periodically under nuclear regulatory. In-service inspections of SG tubes are carried out using eddy current test (ECT) and the defected tubes are usually plugged. Because the radioactivity in the internal of SG chambers limits free access of human worker, remote manipulators are required. In South Korea, Manipulators such as the Zetec SM series and the Westinghouse ROSA series have been used. Such manipulators are rigidly mounted to manways or tube sheets of SG. Confusions for the inspected tubes may occur from deflection of the manipulators. To reduce the deflections of the manipulators for covering the large working areas of tube sheets, sufficient rigidity is required and it leads to the increase of the weight. Such weight increase results in some difficulties for handling and more radiation exposure of human workers. Recently light-weighed mobile robots have been introduced by Westinghouse and Zetec. The robots can move keeping in contact with the tube sheets using devices which are commonly called cam-locks. They are easier to handle and provide no confusion for the position of the inspected tubes. But when the clamping forces are loosed accidently, they can be fall down and light repair works can be performed. This paper provides the design results for a light weighted mobile robot which is recently being developed in cooperation of our institutes

  19. Replacement of alloy 600 by alloy 690 for steam generator tubes and closure heads in PWR; Gains apportes par le changement de materiau dans les generateurs de vapeur et les couvercles de cuve des REP: passage de l'alliage 600 a l'alliage 690

    Energy Technology Data Exchange (ETDEWEB)

    Bioulac, M.; Cipiere, M.F.; Poudroux, G. [FRAMATOME ANP, 92 - Paris-La-Defence (France); Champigny, F.; Mercier, L.; Rouillon, Y.; Vaillant, F. [Electricite de France (EDF), 75 - Paris (France)

    2004-07-01

    The replacement of alloy 600 by alloy 690 for steam generator tubes, tube plugs and closure head penetrations has well fulfilled its expectation concerning resistance to stress corrosion. The first steam generators fitted with tubes in alloy 690 have been operating for 14 years, the first plugs were set more than 20 years ago and the first closure head equipped with adapters in alloy 690 was installed in 1993. The feedback experience on non-destructive testing for these 3 components have shown no cracks. As a consequence the maintenance program has been reduced. A majority of nuclear power plant operators throughout the world have also selected the alloy 690. (A.C.)

  20. 套头式热管余热装置的设计与应用%Design and application of heat recovery steam generator with pullover-style heat tube

    Institute of Scientific and Technical Information of China (English)

    张杰; 张永欢; 张昌建; 许志雨

    2015-01-01

    介绍了套头式热管余热装置的结构原理、工程应用、设计参数的选取,烟气侧强化传热的计算、肋片大小、肋片间距的优化。阐述了热管放热段换热系数的计算及蒸汽流速对热管传热的影响。根据热能平衡理论,给出了热管传热段和热管放热段参数的计算方法。%Presents the structure principle,engineering application,selection of design parameters for heat recovery steam generator (HRSG)with pullover-style heat tube (PHT),the determination of heat tube diameter,calculation of enhancement of heat transfer,size and separation distance optimization of the radiator fin at the flue gas side.Expounds the calculation of heat transfer coefficient in the heat-release side and the influence of vapor speed on heat transfer of the tube.Proposes the calculation methods for parameters at both the heat-emission and the heat-release sides by thermal equilibrium theory.

  1. Aging-related correlation of insulin-degrading enzyme with gamma-secretase-generated products involving insulin and glucose levels in transgenic mice.

    Science.gov (United States)

    Hwang, Dae Y; Cho, Jung S; Kim, Chuel K; Shim, Sun B; Jee, Seung W; Lee, Su H; Seo, Su J; Cho, Joon Y; Lee, Seok H; Kim, Yong K

    2005-09-01

    Insulin-degrading enzyme (IDE) is a 110-kDa thiol zinc-methalloendopeptidase that can cleave small Abeta peptides and the APP intracellular domain (AICD). The aim of this study was to examine aging-related correlation of IDE with gamma-secretase-generated products involving insulin and glucose levels in transgenic brains expressing neuron-specific enolase (NSE)-controlled human mutant presenilin-2 (hPS2m). Herein, we concluded that the levels of IDE expression in transgenic brains were decreased relative to those of control mice at 15 months of age. In parallel, inhibition in the IDE expression at this age underlies to the levels-up of Abeta-42, AICD, gamma-secretase, and glucose with a level-down of insulin. Thus, IDE expression is critical target for the therapeutic trials.

  2. Simultaneous processes of electricity generation and ceftriaxone sodium degradation in an air-cathode single chamber microbial fuel cell

    Science.gov (United States)

    Wen, Qing; Kong, Fanying; Zheng, Hongtao; Yin, Jinling; Cao, Dianxue; Ren, Yueming; Wang, Guiling

    2011-03-01

    A single chamber microbial fuel cell (MFC) with an air-cathode is successfully demonstrated using glucose-ceftriaxone sodium mixtures or ceftriaxone sodium as fuel. Results show that the ceftriaxone sodium can be biodegraded and produce electricity simultaneously. Interestingly, these ceftriaxone sodium-glucose mixtures play an active role in production of electricity. The maximum power density is increased in comparison to 1000 mg L-1 glucose (19 W m-3) by 495% for 50 mg L-1 ceftriaxone sodium + 1000 mg L-1 glucose (113 W m-3), while the maximum power density is 11 W m-3 using 50 mg L-1 ceftriaxone sodium as the sole fuel. Moreover, ceftriaxone sodium biodegradation rate reaches 91% within 24 h using the MFC in comparison with 51% using the traditional anaerobic reactor. These results indicate that some toxic and bio-refractory organics such as antibiotic wastewater might be suitable resources for electricity generation using the MFC technology.

  3. Feeding tube - infants

    Science.gov (United States)

    ... this page: //medlineplus.gov/ency/article/007235.htm Feeding tube - infants To use the sharing features on this page, please enable JavaScript. A feeding tube is a small, soft, plastic tube placed ...

  4. Tube-shape verifier

    Science.gov (United States)

    Anderson, A. N.; Christ, C. R.

    1980-01-01

    Inexpensive apparatus checks accuracy of bent tubes. Assortment of slotted angles and clamps is bolted down to flat aluminum plate outlining shape of standard tube bent to desired configuration. Newly bent tubes are then checked against this outline. Because parts are bolted down, tubes can be checked very rapidly without disturbing outline. One verifier per tube-bending machine can really speed up production in tube-bending shop.

  5. Using Second Harmonic Generation Microscopy to Study the Three-Dimensional Structure of Collagen and its Degradation Mechanism

    Science.gov (United States)

    Mega, Yair

    Collagen is one of the most abundant proteins found in the human body. Its crystalline structure possesses no centrosymmetry, allowing it to emit second-harmonic waves. Second harmonic generation (SHG) microscopy utilizes the latter quality to produce high-resolution images of collagen rich tissues and therefore become a key research tool in the biomedical field. We developed a new model, intended to be used together with second harmonic generation (SHG) microscopy, to thoroughly investigate collagen-based tissues. We use our SHG model to reveal information in real time from enzymatic biochemical processes. We also present a novel method used to measure quantitatively the direction of the fibers within the tissue, from SHG images. Using this method, we were able to reconstruct an angular map of the orientation of collagen fibers from multiple sections across the entire area of a human cornea. The structure we obtained demonstrates the criss-crossing structure of the human cornea, previously suggested in the literature. In addition, we also report work on a unique step-wise three-photon fluorescence excitation discovered in melanin. This unique fluorescence mechanism was exploited to discriminate melanin on a small-size, low-cost and low laser power setup which was used as a prototype for a handheld device. The latter study is a part of a larger on-going effort in our group to explore new diagnosis methods to be used for early skin cancer screening. Finally, this work demonstrates a spectroscopy-based method to correct for blood vessel thickness effect. The method analyzes spectral shift from a molecular imaging agent and correlate the shifts to the length of the optical path in blood. The correction method described in this work is intended to be implemented on a guided catheter near infrared fluorescence (NIRF) intra-vascular imaging system. In this imaging system, this study's results will used to correct for the radial distance between the imaging tip of the

  6. Generations.

    Science.gov (United States)

    Chambers, David W

    2005-01-01

    Groups naturally promote their strengths and prefer values and rules that give them an identity and an advantage. This shows up as generational tensions across cohorts who share common experiences, including common elders. Dramatic cultural events in America since 1925 can help create an understanding of the differing value structures of the Silents, the Boomers, Gen Xers, and the Millennials. Differences in how these generations see motivation and values, fundamental reality, relations with others, and work are presented, as are some applications of these differences to the dental profession.

  7. Diagnostic accuracy of coronary CT angiography using 3{sup rd}-generation dual-source CT and automated tube voltage selection: Clinical application in a non-obese and obese patient population

    Energy Technology Data Exchange (ETDEWEB)

    Mangold, Stefanie [Medical University of South Carolina, Division of Cardiovascular Imaging, Department of Radiology and Radiological Science, Charleston, SC (United States); Eberhard-Karls University Tuebingen, Department of Diagnostic and Interventional Radiology, Tuebingen (Germany); Wichmann, Julian L. [Medical University of South Carolina, Division of Cardiovascular Imaging, Department of Radiology and Radiological Science, Charleston, SC (United States); University Hospital Frankfurt, Department of Diagnostic and Interventional Radiology, Frankfurt (Germany); Schoepf, U.J. [Medical University of South Carolina, Division of Cardiovascular Imaging, Department of Radiology and Radiological Science, Charleston, SC (United States); Medical University of South Carolina, Division of Cardiology, Department of Medicine, Charleston, SC (United States); Caruso, Damiano [Medical University of South Carolina, Division of Cardiovascular Imaging, Department of Radiology and Radiological Science, Charleston, SC (United States); University of Rome ' ' Sapienza' ' , Department of Radiological Sciences, Oncology and Pathology, Rome (Italy); Tesche, Christian [Medical University of South Carolina, Division of Cardiovascular Imaging, Department of Radiology and Radiological Science, Charleston, SC (United States); Heart Centre Munich-Bogenhausen, Department of Cardiology, Munich (Germany); Steinberg, Daniel H.; Bayer, Richard R. [Medical University of South Carolina, Division of Cardiology, Department of Medicine, Charleston, SC (United States); Varga-Szemes, Akos; Stubenrauch, Andrew C.; Biancalana, Matthew; De Cecco, Carlo N. [Medical University of South Carolina, Division of Cardiovascular Imaging, Department of Radiology and Radiological Science, Charleston, SC (United States); Nikolaou, Konstantin [Eberhard-Karls University Tuebingen, Department of Diagnostic and Interventional Radiology, Tuebingen (Germany)

    2017-06-15

    To investigate diagnostic accuracy of 3{sup rd}-generation dual-source CT (DSCT) coronary angiography in obese and non-obese patients. We retrospectively analyzed 76 patients who underwent coronary CT angiography (CCTA) and invasive coronary angiography. Prospectively ECG-triggered acquisition was performed with automated tube voltage selection (ATVS). Patients were dichotomized based on body mass index in groups A (<30 kg/m{sup 2}, n = 37) and B (≥30 kg/m{sup 2}, n = 39) and based on tube voltage in groups C (<120 kV, n = 46) and D (120 kV, n = 30). Coronary arteries were assessed for significant stenoses (≥50 % luminal narrowing) and diagnostic accuracy was calculated. Per-patient overall sensitivity, specificity, positive predictive value, negative predictive value (NPV) and accuracy were 96.9 %, 95.5 %, 93.9 %, 97.7 % and 96.1 %, respectively. Sensitivity and NPV were lower in groups B and D compared to groups A and C, but no statistically significant differences were observed (group A vs. B: sensitivity, 100.0 % vs. 93.3 %, p = 0.9493; NPV, 100 % vs. 95.5 %, p = 0.9812; group C vs. D: sensitivity, 100.0 % vs. 92.3 %, p = 0.8462; NPV, 100.0 % vs. 94.1 %, p = 0.8285). CCTA using 3{sup rd}-generation DSCT and (ATVS) provides high diagnostic accuracy in both non-obese and obese patients. (orig.)

  8. Analysis of organic compounds' degradation and electricity generation in anaerobic fluidized bed microbial fuel cell for coking wastewater treatment.

    Science.gov (United States)

    Liu, Xinmin; Wu, Jianjun; Guo, Qingjie

    2017-02-22

    A single-chambered packing-type anaerobic fluidized microbial fuel cell (AFBMFC) with coking wastewater (CWW) as fuel was built to treat CWW, which not only has high treating efficiency, but also can convert organic matter in wastewater into electricity. AFBMFC was constructed by using anaerobic sludge that was domesticated as inoculation sludge, which was used to biochemically treat CWW. The organic compounds in CWW were extracted by liquid-liquid extraction step by step every day. The extraction phase was concentrated by a rotary evaporator and a nitrogen sweeping device and was analyzed by GC-MS. And the electricity-generation performances of AFBMFC were investigated. The results show that the composition of CWW was complicated, which mainly contains hydrocarbons, phenols, nitrogenous organic compounds, alcohols and aldehydes, esters and acids and so on. After a cycle of anaerobic biochemical treatment, the content of organic compounds in the effluent decreased significantly. After the treatment of AFBMFC, 99.9% phenols, 98.4% alcohol and aldehydes and 95.3% nitrogenous compounds were biodegraded. In the effluent, some new compounds (such as tricosane and dibutyl phthalate) were produced. The chemical oxygen demand (COD) of CWW decreased from 3372 to 559 mg/L in the closed-circuit microbial fuel cell, and the COD removal was 83.4 ± 1.0%. The maximum power density of AFBMFC was 2.13 ± 0.01 mW m(-2).

  9. 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 rela...... to a part of the tube. The invention further relates to a method for creating a flow of a fluid within an at least partly flexible tube by means of a pump element as mentioned above.......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...

  10. Development boiling to sprinkled tube bundle

    Directory of Open Access Journals (Sweden)

    Kracík Petr

    2016-01-01

    Full Text Available This paper presents results of a studied heat transfer coefficient at the surface of a sprinkled tube bundle where boiling occurs. Research in the area of sprinkled exchangers can be divided into two major parts. The first part is research on heat transfer and determination of the heat transfer coefficient at sprinkled tube bundles for various liquids, whether boiling or not. The second part is testing of sprinkle modes for various tube diameters, tube pitches and tube materials and determination of individual modes’ interface. All results published so far for water as the falling film liquid apply to one to three tubes for which the mentioned relations studied are determined in rigid laboratory conditions defined strictly in advance. The sprinkled tubes were not viewed from the operational perspective where there are more tubes and various modes may occur in different parts with various heat transfer values. The article focuses on these processes. The tube is located in a low-pressure chamber where vacuum is generated using an exhauster via ejector. The tube consists of smooth copper tubes of 12 mm diameter placed horizontally one above another.

  11. Development boiling to sprinkled tube bundle

    Science.gov (United States)

    Kracík, Petr; Pospíšil, Jiří

    2016-03-01

    This paper presents results of a studied heat transfer coefficient at the surface of a sprinkled tube bundle where boiling occurs. Research in the area of sprinkled exchangers can be divided into two major parts. The first part is research on heat transfer and determination of the heat transfer coefficient at sprinkled tube bundles for various liquids, whether boiling or not. The second part is testing of sprinkle modes for various tube diameters, tube pitches and tube materials and determination of individual modes' interface. All results published so far for water as the falling film liquid apply to one to three tubes for which the mentioned relations studied are determined in rigid laboratory conditions defined strictly in advance. The sprinkled tubes were not viewed from the operational perspective where there are more tubes and various modes may occur in different parts with various heat transfer values. The article focuses on these processes. The tube is located in a low-pressure chamber where vacuum is generated using an exhauster via ejector. The tube consists of smooth copper tubes of 12 mm diameter placed horizontally one above another.

  12. Revisiting The Second Law of Energy Degradation and Entropy Generation: From Sadi Carnot's Ingenious Reasoning to Holistic Generalization

    Science.gov (United States)

    Kostic, Milivoje M.

    2011-12-01

    Sadi Carnot's ingenious reasoning of reversible cycles (1824) laid foundations for The Second Law before The First Law of energy conservation was even known (Joule 1843) and long before Thermodynamic concepts were established in 1850s. A century later, Bridgman (1941) `complained' that "there are almost as many formulations of The Second Law as there have been discussions of it." Even today, The Second Law remains so obscure, due to the lack of its comprehension, that it continues to attract new efforts at clarification, including this one. The Laws of Thermodynamics have much wider, including philosophical significance and implication, than their simple expressions based on the experimental observations—they are The Fundamental Laws of Nature: The Zeroth (equilibrium existentialism), The First (conservational transformationalism), The Second (irreversible directional transformationalism), and The Third (unattainability of emptiness). They are defining and unifying our comprehension of all existence and transformations in the universe. The forces, due to non-equilibrium of mass-energy in space (non-uniform `concentrations'), causing the mass-energy displacement, thus defining the process direction, are manifested by tendency of mass-energy transfer in time towards common equilibrium—cause-and-effect forced tendency of equi-partition of mass-energy. It should not be confused with local creation of non-equilibrium and/or `organized structures' on expense of `over-all' non-equilibrium, by spontaneous and irreversible conversion (dissipation) of other energy forms into the thermal energy, always and everywhere accompanied with entropy generation (randomized equi-partition of energy per absolute temperature level). The fundamental laws of nature are considered to be axiomatic and many believe they could not be explained, proven or questioned. However, everything may and should be questioned, reasoned, explained and possibly proven. The miracles are until they are

  13. Mycobacterium marinum Degrades Both Triacylglycerols and Phospholipids from Its Dictyostelium Host to Synthesise Its Own Triacylglycerols and Generate Lipid Inclusions.

    Science.gov (United States)

    Barisch, Caroline; Soldati, Thierry

    2017-01-01

    During a tuberculosis infection and inside lipid-laden foamy macrophages, fatty acids (FAs) and sterols are the major energy and carbon source for Mycobacterium tuberculosis. Mycobacteria can be found both inside a vacuole and the cytosol, but how this impacts their access to lipids is not well appreciated. Lipid droplets (LDs) store FAs in form of triacylglycerols (TAGs) and are energy reservoirs of prokaryotes and eukaryotes. Using the Dictyostelium discoideum/Mycobacterium marinum infection model we showed that M. marinum accesses host LDs to build up its own intracytosolic lipid inclusions (ILIs). Here, we show that host LDs aggregate at regions of the bacteria that become exposed to the cytosol, and appear to coalesce on their hydrophobic surface leading to a transfer of diacylglycerol O-acyltransferase 2 (Dgat2)-GFP onto the bacteria. Dictyostelium knockout mutants for both Dgat enzymes are unable to generate LDs. Instead, the excess of exogenous FAs is esterified predominantly into phospholipids, inducing uncontrolled proliferation of the endoplasmic reticulum (ER). Strikingly, in absence of host LDs, M. marinum alternatively exploits these phospholipids, resulting in rapid reversal of ER-proliferation. In addition, the bacteria are unable to restrict their acquisition of lipids from the dgat1&2 double knockout leading to vast accumulation of ILIs. Recent data indicate that the presence of ILIs is one of the characteristics of dormant mycobacteria. During Dictyostelium infection, ILI formation in M. marinum is not accompanied by a significant change in intracellular growth and a reduction in metabolic activity, thus providing evidence that storage of neutral lipids does not necessarily induce dormancy.

  14. Dye removal of AR27 with enhanced degradation and power generation in a microbial fuel cell using bioanode of treated clinoptilolite-modified graphite felt.

    Science.gov (United States)

    Kardi, Seyedeh Nazanin; Ibrahim, Norahim; Darzi, Ghasem Najafpour; Rashid, Noor Aini Abdul; Villaseñor, José

    2017-06-03

    This work studied the performance of a laboratory-scale microbial fuel cell (MFC) using a bioanode that consisted of treated clinoptilolite fine powder coated onto graphite felt (TC-MGF). The results were compared with another similar MFC that used a bare graphite felt (BGF) bioanode. The anode surfaces provided active sites for the adhesion of the bacterial consortium (NAR-2) and the biodegradation of mono azo dye C.I. Acid Red 27. As a result, bioelectricity was generated in both MFCs. A 98% decolourisation rate was achieved using the TC-MGF bioanode under a fed-batch operation mode. Maximum power densities for BGF and TC-MGF bioanodes were 458.8 ± 5.0 and 940.3 ± 4.2 mW m(-2), respectively. GC-MS analyses showed that the dye was readily degraded in the presence of the TC-MGF bioanode. The MFC using the TC-MGF bioanode showed a stable biofilm with no biomass leached out for more than 300 h operation. In general, MFC performance was substantially improved by the fabricated TC-MGF bioanode. It was also found that the TC-MGF bioanode with the stable biofilm presented the nature of exopolysaccharide (EPS) structure, which is suitable for the biodegradation of the azo dye. In fact, the EPS facilitated the shuttling of electrons to the bioanode for the generation of bioelectricity.

  15. The development of radiation hardened robot for nuclear facility; development of ultrasonic guided wave evaluation technology for the in-service/post-repair inspection of steam generator tubings

    Energy Technology Data Exchange (ETDEWEB)

    Cho, Youn Ho [Inje University, Kimhae (Korea)

    2002-04-01

    The Potential of Ultrasonic Guided Waves which can propagate along the geometry of structures was explored for the inspection of such various components of nuclear power plants as tubings, pipings and plate-like structures etc. In this project, the fundamental research on the various aspects of guided wave modal characteristics was carried out to provide physically based guidelines which are essential to implement the guided waves as a promising inspection tool in the near future. The efforts for guided wave research include both theoretical and experimental works to make it possible to transfer the technology to power industry beyond the scope of pure academic subject. In the theoretical works, the softwares for the dispersion curves and wave structures of both layered structures and cylindrical ones were developed in the aims of mode identification and determination of probe design parameters. 40 refs., 92 figs., 14 tabs. (Author)

  16. US PWR steam generator management: An overview

    Energy Technology Data Exchange (ETDEWEB)

    Welty, C.S. Jr. [Electric Power Research Institute, Palo Alto, CA (United States)

    1997-02-01

    This paper provides an overview on the status of steam generator management activities in US PWRs, and includes: (1) an overview of the impact of steam generator problems; (2) a brief discussion of historical damage trends and the current damage mechanism of most concern; (3) a discussion of the elements of {open_quotes}steam generator management{close_quotes}; and (4) a description of the approach being followed to implement a degradation-specific protocol for tubing inspection and repair. This paper was prepared in conjunction with another paper presented during the Plenary Session of this Conference, {open_quotes}Steam Generator Degradation: Current Mitigation Strategies for Controlling Corrosion{close_quotes}, and is provided as a supplement to that material.

  17. Efficient degradation of TCE in groundwater using Pd and electro-generated H2 and O2: a shift in pathway from hydrodechlorination to oxidation in the presence of ferrous ions.

    Science.gov (United States)

    Yuan, Songhu; Mao, Xuhui; Alshawabkeh, Akram N

    2012-03-20

    Degradation of trichloroethylene (TCE) in simulated groundwater by Pd and electro-generated H(2) and O(2) is investigated in the absence and presence of Fe(II). In the absence of Fe(II), hydrodechlorination dominates TCE degradation, with accumulation of H(2)O(2) up to 17 mg/L. Under weak acidity, low concentrations of oxidizing •OH radicals are detected due to decomposition of H(2)O(2), slightly contributing to TCE degradation via oxidation. In the presence of Fe(II), the degradation efficiency of TCE at 396 μM improves to 94.9% within 80 min. The product distribution proves that the degradation pathway shifts from 79% hydrodechlorination in the absence of Fe(II) to 84% •OH oxidation in the presence of Fe(II). TCE degradation follows zeroth-order kinetics with rate constants increasing from 2.0 to 4.6 μM/min with increasing initial Fe(II) concentration from 0 to 27.3 mg/L at pH 4. A good correlation between TCE degradation rate constants and •OH generation rate constants confirms that •OH is the predominant reactive species for TCE oxidation. Presence of 10 mM Na(2)SO(4), NaCl, NaNO(3), NaHCO(3), K(2)SO(4), CaSO(4), and MgSO(4) does not significantly influence degradation, but sulfite and sulfide greatly enhance and slightly suppress degradation, respectively. A novel Pd-based electrochemical process is proposed for groundwater remediation.

  18. Failure of a MEA reclaimer tube bundle due to corrosion

    Energy Technology Data Exchange (ETDEWEB)

    Shaban, H.; Abdo, M.S.E.; Lal, D.P.

    1988-08-01

    The removal of sulphur compounds from natural gas used in ammonia production is carried out by scrubbing with monoethanol amine (MEA). To avoid build up of corrosion and degradation products, a portion of the circulating MEA solution is passed through a reclaimer. This is essentially a kettle-type reboiler with a tube bundle made of 316L stainless steel. Occasional failures of the tube bundle due to pitting corrosion have been reported. It is suggested that the excessive pitting corrosion observed on the upper rows of the tube bundle could be partly due to high steam temperature but mainly due to the liquid level falling below the tubes leaving an accumulation of corrosive degradation products on the exposed surfaces, normally these corrosive products remain diluted in the MEA solution and cause little corrosion of the covered tubes. Their concentration on the dry upper layers of the hot metal tubes, however, leads to excessive corrosion. (U.K.).

  19. A method and sensor for the eddy current non destructive testing of thin tubes; Procede de controle non destructif d`un tube mince par courants de Foucault

    Energy Technology Data Exchange (ETDEWEB)

    Sartre, B.; Miller, D.; Placko, D.

    1995-06-02

    In order to control the wear (cracking or thinning) of vapor generator tubes, especially in PWR reactors, due to the friction between the tubes and dampers, an eddy current control system is proposed where the transducer is run through the tubes, and measures the tube wall thickness or tube-block clearance through impedance measurements, taking into account the variation of the sensor-to-tube distance. 8 fig.

  20. Speciation analysis of arsenic in biological matrices by automated hydride generation-cryotrapping-atomic absorption spectrometry with multiple microflame quartz tube atomizer (multiatomizer).

    Science.gov (United States)

    This paper describes an automated system for the oxidation state specific speciation of inorganic and methylated arsenicals by selective hydride generation - cryotrapping- gas chromatography - atomic absorption spectrometry with the multiatomizer. The corresponding arsines are ge...

  1. Ag/g-C3N4 catalyst with superior catalytic performance for the degradation of dyes: a borohydride-generated superoxide radical approach

    Science.gov (United States)

    Fu, Yongsheng; Huang, Ting; Zhang, Lili; Zhu, Junwu; Wang, Xin

    2015-08-01

    A straightforward approach is developed for fabrication of a visible-light-driven Ag/g-C3N4 catalyst. Morphological observation shows that the g-C3N4 sheets are decorated with highly dispersed Ag nanoparticles having an average size of 5.6 nm. The photocatalytic activity measurements demonstrate that the photocatalytic degradation rates of methyl orange (MO), methylene blue (MB), and neutral dark yellow GL (NDY-GL) over Ag/g-C3N4-4 can reach up to 98.2, 99.3 and 99.6% in the presence of borohydride ions (BH4-) only with 8, 45, and 16 min visible light irradiation, respectively. The significant enhancement in photoactivity of the catalyst is mainly attributed to the high dispersity and smaller size of Ag nanoparticles, the strong surface plasmon resonance (SPR) effect of metallic Ag nanoparticles, the efficient separation of photogenerated charge carriers, the additional superoxide radicals (O&z.rad;-2) generated from the reduction of dissolved oxygen in the presence of BH4- and the synergistic effect of Ag nanoparticles and g-C3N4.A straightforward approach is developed for fabrication of a visible-light-driven Ag/g-C3N4 catalyst. Morphological observation shows that the g-C3N4 sheets are decorated with highly dispersed Ag nanoparticles having an average size of 5.6 nm. The photocatalytic activity measurements demonstrate that the photocatalytic degradation rates of methyl orange (MO), methylene blue (MB), and neutral dark yellow GL (NDY-GL) over Ag/g-C3N4-4 can reach up to 98.2, 99.3 and 99.6% in the presence of borohydride ions (BH4-) only with 8, 45, and 16 min visible light irradiation, respectively. The significant enhancement in photoactivity of the catalyst is mainly attributed to the high dispersity and smaller size of Ag nanoparticles, the strong surface plasmon resonance (SPR) effect of metallic Ag nanoparticles, the efficient separation of photogenerated charge carriers, the additional superoxide radicals (O&z.rad;-2) generated from the reduction of

  2. Robust Replication Control Is Generated by Temporal Gaps between Licensing and Firing Phases and Depends on Degradation of Firing Factor Sld2

    Directory of Open Access Journals (Sweden)

    Karl-Uwe Reusswig

    2016-10-01

    Full Text Available Temporal separation of DNA replication initiation into licensing and firing phases ensures the precise duplication of the genome during each cell cycle. Cyclin-dependent kinase (CDK is known to generate this separation by activating firing factors and at the same time inhibiting licensing factors but may not be sufficient to ensure robust separation at transitions between both phases. Here, we show that a temporal gap separates the inactivation of firing factors from the re-activation of licensing factors during mitosis in budding yeast. We find that gap size critically depends on phosphorylation-dependent degradation of the firing factor Sld2 mediated by CDK, DDK, Mck1, and Cdc5 kinases and the ubiquitin-ligases Dma1/2. Stable mutants of Sld2 minimize the gap and cause increased genome instability in an origin-dependent manner when combined with deregulation of other replication regulators or checkpoint mechanisms. Robust separation of licensing and firing phases therefore appears indispensable to safeguard genome stability.

  3. A hot plate solar cooker with electricity generation-Combining a parabolic trough mirror with a sidney tube and heat pipe

    NARCIS (Netherlands)

    Kaasjager, A.D.J.; Moeys, G.P.G.

    2012-01-01

    Solar cookers supply clean and sustainable energy for cooking and so limit the use of wood or charcoal. A new type of solar cooker is developed with a hot plate. The hot plate offers comfortable access to the food under preparation. The hot plate opens up the opportunity to generate small amounts of

  4. A hot plate solar cooker with electricity generation-Combining a parabolic trough mirror with a sidney tube and heat pipe

    NARCIS (Netherlands)

    Kaasjager, A.D.J.; Moeys, G.P.G.

    2012-01-01

    Solar cookers supply clean and sustainable energy for cooking and so limit the use of wood or charcoal. A new type of solar cooker is developed with a hot plate. The hot plate offers comfortable access to the food under preparation. The hot plate opens up the opportunity to generate small amounts of

  5. Development of a 1D thermal-hydraulic analysis code for once-through steam generator in SMRs using straight tubes

    Energy Technology Data Exchange (ETDEWEB)

    Park, Youngjae; Kim, Iljin; Kim, Hyungdae [Kyung Hee University, Yongin (Korea, Republic of)

    2015-10-15

    Diverse integral/small-modular reactors (SMRs) have been developed. Once-through steam generator (OTSG) which generates superheated steam without steam separator and dryer was used in the SMRs to reduce volume of steam generator. It would be possible to design a new steam generator with best estimate thermal-hydraulic codes such as RELAP and MARS. However, it is not convenience to use the general purpose thermal-hydraulic analysis code to design a specific component of nuclear power plants. A widely used simulation tool for thermal-hydraulic analysis of drum-type steam generators is ATHOS, which allows 3D analysis. On the other hand, a simple 1D thermal-hydraulic analysis code might be accurate enough for the conceptual design of OTSG. In this study, thermal-hydraulic analysis code for conceptual design of OTSG was developed using 1D homogeneous equilibrium model (HEM). A benchmark calculation was also conducted to verify and validate the prediction accuracy of the developed code by comparing with the analysis results with MARS. Finally, conceptual design of OTSG was conducted by the developed code. A simple 1D thermal-hydraulic analysis code was developed for the purpose of conceptual design OTSG for SMRs. A set of benchmark calculations was conducted to verify and validate the analysis accuracy of the developed code by comparing results obtained with a best-estimated thermal-hydraulic analysis code, MARS. Finally, analysis of two different OTSG design concepts with superheating and recirculation was demonstrated using the developed code.

  6. Establishment of database and network for research of stream generator and state of the art technology review

    Energy Technology Data Exchange (ETDEWEB)

    Choi, Jae Bong; Hur, Nam Su; Moon, Seong In; Seo, Hyeong Won; Park, Bo Kyu; Park, Sung Ho; Kim, Hyung Geun [Sungkyunkwan Univ., Seoul (Korea, Republic of)

    2004-02-15

    A significant number of steam generator tubes are defective and are removed from service or repaired world widely. This wide spread damage has been caused by diverse degradation mechanisms, some of which are difficult to detect and predict. Regarding domestic nuclear power plants, also, the increase of number of operating nuclear power plants and operating periods may result in the increase of steam generator tube failure. So, it is important to carry out the integrity evaluation process to prevent the steam generator tube damage. There are two objectives of this research. The one is to make database for the research of steam generator at domestic research institution. It will increase the efficiency and capability of limited domestic research resources by sharing data and information through network organization. Also, it will enhance the current standard of integrity evaluation procedure that is considerably conservative but can be more reasonable. The second objective is to establish the standard integrity evaluation procedure for steam generator tube by reviewing state of the art technology. The research resources related to steam generator tubes are managed by the established web-based database system. The following topics are covered in this project: development of web-based network for research on steam generator tubes review of state of the art technology.

  7. Feeding tube insertion - gastrostomy

    Science.gov (United States)

    ... this page: //medlineplus.gov/ency/article/002937.htm Feeding tube insertion - gastrostomy To use the sharing features on this page, please enable JavaScript. A gastrostomy feeding tube insertion is the placement of a feeding ...

  8. Neural Tube Defects

    Science.gov (United States)

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

  9. β-amyloid fibrils in Alzheimer disease are not inert when bound to copper ions but can degrade hydrogen peroxide and generate reactive oxygen species.

    Science.gov (United States)

    Mayes, Jennifer; Tinker-Mill, Claire; Kolosov, Oleg; Zhang, Hao; Tabner, Brian J; Allsop, David

    2014-04-25

    According to the "amyloid cascade" hypothesis of Alzheimer disease, the formation of Aβ fibrils and senile plaques in the brain initiates a cascade of events leading to the formation of neurofibrillary tangles, neurodegeneration, and the symptom of dementia. Recently, however, emphasis has shifted away from amyloid fibrils as the predominant toxic form of Aβ toward smaller aggregates, referred to as "soluble oligomers." These oligomers have become one of the prime suspects for involvement in the early oxidative damage that is evident in this disease. This raises the question whether or not Aβ fibrils are actually "inert tombstones" present at the end of the aggregation process. Here we show that, when Aβ(1-42) aggregates, including fibrils, are bound to Cu(II) ions, they retain their redox activity and are able to degrade hydrogen peroxide (H2O2) with the formation of hydroxyl radicals and the consequent oxidation of the peptide (detected by formation of carbonyl groups). We find that this ability increases as the Cu(II):peptide ratio increases and is accompanied by changes in aggregate morphology, as determined by atomic force microscopy. When aggregates are prepared in the copresence of Cu(II) and Zn(II) ions, the ratio of Cu(II):Zn(II) becomes an important factor in the degeneration of H2O2, the formation of carbonyl groups in the peptide, and in aggregate morphology. We believe, therefore, that Aβ fibrils can destroy H2O2 and generate damaging hydroxyl radicals and, so, are not necessarily inert end points.

  10. Vibrations of tube arrays in transversal flow

    Energy Technology Data Exchange (ETDEWEB)

    Gibert, R.J.; Villard, B. (C.E.N. Saclay, Gif-sur-Yvette (France)); Chabrerie, J. (Ste Fives-Cail-Babcok, La Courneuve, (France)); Sagner, V. (Ste Bertin, Plaisir (France))

    1981-01-01

    The vibrations induced in tube arrays by a transversal flow are of great practical interest because of their destructive effects especially on heat exchangers. Though turbulence can significantly excite the tubes by itself, most intense vibrations are still caused by two fluid-elastic phenomena: - The << lock-in >> effect: The basic phenomenon consists of a generation and a synchronization of vortex shedding by a transversal tube motion when its frequency approaches the shedding frequency and when its level is large enough. The so modified vortex shedding generates much more intense vibrations. The lock-in effects is well known for a single cylinder. Less results have been obtained for bundles. - The whirling instability: In a tube row or a bundle, quasi-steady forces are generated by the displacements of the tubes in the flow field. Adjacent tubes are disymmetrically coupled by these forces and instability can appear beyond a critical flow velocity. For the tube rows H.J. Connors has shown that the phenomena are characterized by a coefficient c (which is a function of the pitch).

  11. Dynamic Response and Fracture of Composite Gun Tubes

    Directory of Open Access Journals (Sweden)

    Jerome T. Tzeng

    2001-01-01

    Full Text Available The fracture behavior due to dynamic response in a composite gun tube subjected to a moving pressure has been investigated. The resonance of stress waves result in very high amplitude and frequency strains in the tube at the instant and location of pressure front passage as the velocity of the projectile approaches a critical value. The cyclic stresses can accelerate crack propagation in the gun tube with an existing imperfection and significantly shorten the fatigue life of gun tubes. The fracture mechanism induced by dynamic amplification effects is particularly critical for composite overwrap barrels because of a multi-material construction, anisotropic material properties, and the potential of thermal degradation.

  12. Steam generators

    Energy Technology Data Exchange (ETDEWEB)

    Beckmann, G.; Gilli, P.V.; Fritz, K.; Lippitsch, J.

    1975-12-02

    A steam generator is disclosed which is particularly adapted to be used in nuclear power plants. A casing is provided with an inlet and outlet to receive and discharge a primary heating fluid from which heat is to be extracted. A pair of tube plates extend across the interior of the casing at the region of the inlet and outlet thereof, and a plurality of tubes extend along the interior of the casing and are connected in parallel between the tube plates with all of the tubes having open ends communicating with the inlet and outlet of the casing so that the primary heating fluid will flow through the interior of the tubes while a fluid in the casing at the exterior of the tubes will extract heat from the primary fluid. The casing has between the tubes at the region of the inlet a superheating chamber and at the region of the outlet a preheating chamber and between the latter chambers an evaporating chamber, the casing receiving water through an inlet at the preheating chamber and discharging superheated steam through an outlet at the superheating chamber. A separator communicates with the evaporating chamber to receive a mixture of steam and water therefrom for separating the steam from the water and for delivering the separated steam to the superheating chamber.

  13. Intercostal drainage tube or intracardiac drainage tube?

    Directory of Open Access Journals (Sweden)

    N Anitha

    2016-01-01

    Full Text Available Although insertion of chest drain tubes is a common medical practice, there are risks associated with this procedure, especially when inexperienced physicians perform it. Wrong insertion of the tube has been known to cause morbidity and occasional mortality. We report a case where the left ventricle was accidentally punctured leading to near-exsanguination. This report is to highlight the need for experienced physicians to supervise the procedure and train the younger physician in the safe performance of the procedure.

  14. Optimizing the Thermoacoustic Pulse Tube Refrigerator Performances

    Directory of Open Access Journals (Sweden)

    E. V. Blagin

    2014-01-01

    Full Text Available The article deals with research and optimization of the thermoacoustic pulse tube refrigerator to reach a cryogenic temperature level. The refrigerator is considered as a thermoacoustic converter based on the modified Stirling cycle with helium working fluid. A sound pressure generator runs as a compressor. Plant model comprises an inner heat exchanger, a regenerative heat exchanger, a pulse tube, hot and cold heat exchangers at its ends, an inertial tube with the throttle, and a reservoir. A model to calculate the pulse tube thermoacoustic refrigerator using the DeltaEC software package has been developed to be a basis for calculation techniques of the pulse tube refrigerator. Momentum, continuity, and energy equations for helium refrigerant are solved according to calculation algorithm taking into account the porosity of regenerator and heat exchangers. Optimization of the main geometric parameters resulted in decreasing temperature of cold heat exchanger by 41,7 K. After optimization this value became equal to 115,01 K. The following parameters have been optimized: diameters of the feeding and pulse tube and heat exchangers, regenerator, lengths of the regenerator and pulse and inertial tubes, as well as initial pressure. Besides, global minimum of temperatures has been searched at a point of local minima corresponding to the optimal values of abovementioned parameters. A global-local minima difference is 0,1%. Optimized geometric and working parameters of the thermoacoustic pulse tube refrigerator are presented.

  15. Modelling Fluidelastic Instability Forces in Tube Arrays

    Science.gov (United States)

    Anderson, J. Burns

    Historically, heat exchangers have been among the most failure prone components in nuclear power plants. Most of these failures are due to tube failures as a result of corrosion, fatigue and fretting wear. Fatigue and fretting wear are a result of flow induced vibration through turbulent buffeting and fluidelastic instability mechanisms. Fluidelastic instability is by far the most important and complex mechanism. This research deals with modelling fluidelastic instability and the resulting tube response. The proposed time domain model uses the concept of a flow cell (Hassan & Hayder [16]) to represent the complex flow field inside a shell and tube heat exchanger and accounts for temporal variations in the flow separation points as a result of tube motion. The fluidelastic forces are determined by predicting the attachment lengths. The predicted forces are used to simulate the response of a single flexible tube inside a shell and tube heat exchanger. It was found that accounting for temporal variations in the separation points predicted lower critical flow velocities, than that of fixed attachment and separation points. Once unstable a phase lag is predicted between the fluidelastic forces and tube response. It was determined that the predicted critical flow velocities agreed well with available experimental data. The developed model represents an important step towards a realistic fluidelastic instability model which can be used to design the new generation nuclear steam generators.

  16. Air flow exploration of abrasive feed tube

    Science.gov (United States)

    Zhang, Shijin; Li, Xiaohong; Gu, Yilei

    2009-12-01

    An abrasive water-jet cutting process is one in which water pressure is raised to a very high pressure and forced through a very small orifice to form a very thin high speed jet beam. This thin jet beam is then directed through a chamber and then fed into a secondary nozzle, or mixing tube. During this process, a vacuum is generated in the chamber, and garnet abrasives and air are pulled into the chamber, through an abrasive feed tube, and mixes with this high speed stream of water. Because of the restrictions introduced by the abrasive feed tube geometry, a vacuum gradient is generated along the tube. Although this phenomenon has been recognized and utilized as a way to monitor nozzle condition and abrasive flowing conditions, yet, until now, conditions inside the abrasive feed line have not been completely understood. A possible reason is that conditions inside the abrasive feed line are complicated. Not only compressible flow but also multi-phase, multi-component flow has been involved in inside of abrasive feed tube. This paper explored various aspects of the vacuum creation process in both the mixing chamber and the abrasive feed tube. Based on an experimental exploration, an analytical framework is presented to allow theoretical calculations of vacuum conditions in the abrasive feed tube.

  17. A miniature high repetition rate shock tube.

    Science.gov (United States)

    Tranter, R S; Lynch, P T

    2013-09-01

    A miniature high repetition rate shock tube with excellent reproducibility has been constructed to facilitate high temperature, high pressure, gas phase experiments at facilities such as synchrotron light sources where space is limited and many experiments need to be averaged to obtain adequate signal levels. The shock tube is designed to generate reaction conditions of T > 600 K, P shock waves with predictable characteristics are created, repeatably. Two synchrotron-based experiments using this apparatus are also briefly described here, demonstrating the potential of the shock tube for research at synchrotron light sources.

  18. Pulse Tube Refrigerator

    Science.gov (United States)

    Matsubara, Yoichi

    The pulse tube refrigerator is one of the regenerative cycle refrigerators such as Stirling cycle or Gifford-McMahon cycle which gives the cooling temperature below 150 K down to liquid helium temperature. In 1963, W. E. Gifford invented a simple refrigeration cycle which is composed of compressor, regenerator and simple tube named as pulse tube which gives a similar function of the expander in Stirling or Gifford-McMahon cycle. The thermodynamically performance of this pulse tube refrigerator is inferior to that of other regenerative cycles. In 1984, however, Mikulin and coworkers made a significant advance in pulse tube configuration called as orifice pulse tube. After this, several modifications of the pulse tube hot end configuration have been developed. With those modifications, the thermodynamic performance of the pulse tube refrigerator became the same order to that of Stirling and Gifford-McMahon refrigerator. This article reviews the brief history of the pulse tube refrigerator development in the view point of its thermodynamically efficiency. Simplified theories of the energy flow in the pulse tube have also been described.

  19. STAC -- a new Swedish code for statistical analysis of cracks in SG-tubes

    Energy Technology Data Exchange (ETDEWEB)

    Poern, K. [Poern Consulting, Nykoeping (Sweden)

    1997-02-01

    Steam generator (SG) tubes in pressurized water reactor plants are exposed to various types of degradation processes, among which stress corrosion cracking in particular has been observed. To be able to evaluate the safety importance of such cracking of SG-tubes one has to have a good and empirically founded knowledge about the scope and the size of the cracks as well as the rate of their continuous growth. The basis of experience is to a large extent constituted of the annually performed SG-inspections and crack sizing procedures. On the basis of this experience one can estimate the distribution of existing crack lengths, and modify this distribution with regard to maintenance (plugging) and the predicted rate of crack propagation. Finally, one can calculate the rupture probability of SG-tubes as a function of a given critical crack length. On account of the Swedish Nuclear Power Inspectorate an introductory study has been performed in order to get a survey of what has been done elsewhere in this field. The study resulted in a proposal of a computerizable model to be able to estimate the distribution of true cracks, to modify this distribution due to the crack growth and to compute the probability of tube rupture. The model has now been implemented in a compute code, called STAC (STatistical Analysis of Cracks). This paper is aimed to give a brief outline of the model to facilitate the understanding of the possibilities and limitations associated with the model.

  20. New generation of space TWTAs

    Science.gov (United States)

    Lewis, G. C.; Sosa, E. N.

    1992-03-01

    A new generation of space qualified traveling wave tube amplifiers has been developed and is ready for system application. This new generation of hardware satisfies the system designer's desire for higher efficiency, lighter weight and smaller size hardware at no degradation of life, reliability and performance. Recent developments in TWTA technology is available for both regulated and unregulated bus spacecraft. EPC efficiencies in excess of 95 percent and TWT efficiencies above 60 percent are a reality. Weight reductions are achieved with new packaging techniques. Additionally, single (one TWT/one EPC) and dual (two TWT's/one EPC) TWTA trade-offs are discussed for system consideration. Finally, currently available options such as linearization and automatic restart capability are presented.

  1. Heated Tube Facility

    Data.gov (United States)

    Federal Laboratory Consortium — The Heated Tube Facility at NASA GRC investigates cooling issues by simulating conditions characteristic of rocket engine thrust chambers and high speed airbreathing...

  2. Fuel nozzle tube retention

    Energy Technology Data Exchange (ETDEWEB)

    Cihlar, David William; Melton, Patrick Benedict

    2017-02-28

    A system for retaining a fuel nozzle premix tube includes a retention plate and a premix tube which extends downstream from an outlet of a premix passage defined along an aft side of a fuel plenum body. The premix tube includes an inlet end and a spring support feature which is disposed proximate to the inlet end. The premix tube extends through the retention plate. The spring retention feature is disposed between an aft side of the fuel plenum and the retention plate. The system further includes a spring which extends between the spring retention feature and the retention plate.

  3. Biphasic function of focal adhesion kinase in endothelial tube formation induced by fibril-forming collagens.

    Science.gov (United States)

    Nakamura, Junko; Shigematsu, Satoshi; Yamauchi, Keishi; Takeda, Teiji; Yamazaki, Masanori; Kakizawa, Tomoko; Hashizume, Kiyoshi

    2008-10-03

    Migration and tube formation of endothelial cells are important in angiogenesis and require a coordinated response to the extra-cellular matrix (ECM) and growth factor. Since focal adhesion kinase (FAK) integrates signals from both ECM and growth factor, we investigated its role in angiogenesis. Type I and II collagens are fibril-forming collagens and stimulate human umbilical vein endothelial cells (HUVECs) to form tube structure. Although knockdown of FAK restrained cell motility and resulted in inhibition of tube formation, FAK degradation and tube formation occurred simultaneously after incubation with fibril-forming collagens. The compensation for the FAK degradation by a calpain inhibitor or transient over-expression of FAK resulted in disturbance of tube formation. These phenomena are specific to fibril-forming collagens and mediated via alpha2beta1 integrin. In conclusion, our data indicate that FAK is functioning in cell migration, but fibril-forming collagen-induced FAK degradation is necessary for endothelial tube formation.

  4. Self-induced bio-potential and graphite electron accepting conditions enhances petroleum sludge degradation in bio-electrochemical system with simultaneous power generation.

    Science.gov (United States)

    Mohan, S Venkata; Chandrasekhar, K

    2011-10-01

    Bio-electrochemical treatment (BET) documented effective degradation of real field petroleum sludge over the conventional anaerobic treatment (AnT). BET (41.08%) operation showed enhanced total petroleum hydrocarbons (TPH) removal over AnT (20.72%). Aromatic fraction visualized higher removal (75.54%) compared to other TPH fractions viz., aliphatics, asphaltenes and NSO (nitrogen, sulfur and oxygen) during BET operation. Higher ring aromatics (5-6) documented easy degradation in BET, while AnT was limited to lower ring (2-3) compounds. Voltammetric analysis evidenced simultaneous redox behavior during BET operation due to presence of graphite electrode as electron acceptor, while AnT showed extended reduction behavior only. Self-induced primary and secondary oxidation reactions and capacitive-deionization might have enhanced the degradation capability of BET. BET documented higher charge/capacitance (2810 mJ/1120 mF) than AnT (450 mJ/180 mF). Power output corroborated well with observed results supporting BET performance as fuel cell. Electrodes offer a potential alternative electron acceptor for promoting the degradation of organic contaminants.

  5. Applicable methods for NDT of tubes

    Energy Technology Data Exchange (ETDEWEB)

    Pitkaenen, J.; Lipponen, A.; Kauppinen, P. [VTT Industrial Systems Espoo (Finland)

    2004-05-01

    For inside inspection of tubes, eddy current testing (ET) and internal rotating ultrasonic inspection (IRIS) are mainly used at the moment. Special eddy current method, remote field technique (RFEC) is being used to some extent, but normally only for ferritic tubes. This paper presents a review of techniques that can be used for internal inspections of tubes in boilers, heat exchangers and steam generators. Material affects the choice of the method, considering given defect type and detectability with the selected technique. In general ET methods are used for inspection of non- ferromagnetic tubes and IRIS and RFEC methods for inspection of ferromagnetic tubes. New techniques have been introduced, to determine the tube condition accurately. One of the developed techniques is for instance inspection of the internal surface by combination of dye penetrant and optical laser inspection. New applications of ultrasonic techniques include defect detection and characterisation by tip diffraction echoes, defect analysis by echo dynamics and the TOFD-technique for defect sizing. Ultrasonic guided waves have a great potential to increase inspection speed for defect detection, although sizing is still under development. For inspection of ferromagnetic tubes, a method based on magnetic flux leakage has been used. In addition to the basic techniques visualisation of the measured data is one of the. key factors for improved exploitation of the inspection results. (orig.)

  6. Friction Modeling in Concentric Tube Robots.

    Science.gov (United States)

    Lock, Jesse; Dupont, Pierre E

    2011-01-01

    Concentric tube robots are a novel class of continuum robots that are constructed by combining pre-curved elastic tubes such that the overall shape of the robot is a function of the relative rotations and translations of the constituent tubes. Frictionless kinematic and quasistatic force models for this class of robots have been developed that incorporate bending and twisting of the tubes. Experimental evaluation of these models has revealed, however, a directional dependence of tube rotation on robot shape that is not predicted by these models. To explain this behavior, this paper models the contributions of friction arising from two sources: the distributed forces of contact between the tubes along their length and the concentrated bending moments generated at discontinuities in curvature and at the boundaries. It is shown that while friction due to distributed forces is insufficient to explain the experimentally observed tube twisting, a simple model of frictional torque arising from concentrated moments provides a good match with the experimental data.

  7. Evidence of the generation of isosaccharinic acids and their subsequent degradation by local microbial consortia within hyper-alkaline contaminated soils, with relevance to intermediate level radioactive waste disposal.

    Science.gov (United States)

    Rout, Simon P; Charles, Christopher J; Garratt, Eva J; Laws, Andrew P; Gunn, John; Humphreys, Paul N

    2015-01-01

    The contamination of surface environments with hydroxide rich wastes leads to the formation of high pH (>11.0) soil profiles. One such site is a legacy lime works at Harpur Hill, Derbyshire where soil profile indicated in-situ pH values up to pH 12. Soil and porewater profiles around the site indicated clear evidence of the presence of the α and β stereoisomers of isosaccharinic acid (ISA) resulting from the anoxic, alkaline degradation of cellulosic material. ISAs are of particular interest with regards to the disposal of cellulosic materials contained within the intermediate level waste (ILW) inventory of the United Kingdom, where they may influence radionuclide mobility via complexation events occurring within a geological disposal facility (GDF) concept. The mixing of uncontaminated soils with the alkaline leachate of the site resulted in ISA generation, where the rate of generation in-situ is likely to be dependent upon the prevailing temperature of the soil. Microbial consortia present in the uncontaminated soil were capable of surviving conditions imposed by the alkaline leachate and demonstrated the ability to utilise ISAs as a carbon source. Leachate-contaminated soil was sub-cultured in a cellulose degradation product driven microcosm operating at pH 11, the consortia present were capable of the degradation of ISAs and the generation of methane from the resultant H2/CO2 produced from fermentation processes. Following microbial community analysis, fermentation processes appear to be predominated by Clostridia from the genus Alkaliphilus sp, with methanogenesis being attributed to Methanobacterium and Methanomassiliicoccus sp. The study is the first to identify the generation of ISA within an anthropogenic environment and advocates the notion that microbial activity within an ILW-GDF is likely to influence the impact of ISAs upon radionuclide migration.

  8. Evidence of the generation of isosaccharinic acids and their subsequent degradation by local microbial consortia within hyper-alkaline contaminated soils, with relevance to intermediate level radioactive waste disposal.

    Directory of Open Access Journals (Sweden)

    Simon P Rout

    Full Text Available The contamination of surface environments with hydroxide rich wastes leads to the formation of high pH (>11.0 soil profiles. One such site is a legacy lime works at Harpur Hill, Derbyshire where soil profile indicated in-situ pH values up to pH 12. Soil and porewater profiles around the site indicated clear evidence of the presence of the α and β stereoisomers of isosaccharinic acid (ISA resulting from the anoxic, alkaline degradation of cellulosic material. ISAs are of particular interest with regards to the disposal of cellulosic materials contained within the intermediate level waste (ILW inventory of the United Kingdom, where they may influence radionuclide mobility via complexation events occurring within a geological disposal facility (GDF concept. The mixing of uncontaminated soils with the alkaline leachate of the site resulted in ISA generation, where the rate of generation in-situ is likely to be dependent upon the prevailing temperature of the soil. Microbial consortia present in the uncontaminated soil were capable of surviving conditions imposed by the alkaline leachate and demonstrated the ability to utilise ISAs as a carbon source. Leachate-contaminated soil was sub-cultured in a cellulose degradation product driven microcosm operating at pH 11, the consortia present were capable of the degradation of ISAs and the generation of methane from the resultant H2/CO2 produced from fermentation processes. Following microbial community analysis, fermentation processes appear to be predominated by Clostridia from the genus Alkaliphilus sp, with methanogenesis being attributed to Methanobacterium and Methanomassiliicoccus sp. The study is the first to identify the generation of ISA within an anthropogenic environment and advocates the notion that microbial activity within an ILW-GDF is likely to influence the impact of ISAs upon radionuclide migration.

  9. Techniques for Thermal Damping in Tube Bundles

    Directory of Open Access Journals (Sweden)

    QAMAR IQBAL

    2010-10-01

    Full Text Available Flow-induced vibration in heat exchangers has been a source of concern in the process, power generation and nuclear industry for several decades. Damping has a major influence on the flow induced vibrations and is dependant on a variety of factors such as mechanical properties of the tube material, geometry of intermediate supports, the physical properties of shell-side fluid, type of tube motion, number of supports, tube frequency, shell-side temperature etc. Various damping mechanisms have been identified and quantified. Generally the effects of the higher operating temperatures on the various damping mechanisms are neglected in the general design procedure. This paper focuses on the thermal aspects of damping mechanisms subjected to single phase cross-flow in shell and tube heat exchanger and a comparison is carried out safer design based on experimental and empirical formulations.

  10. Molybdenum Tube Characterization report

    Energy Technology Data Exchange (ETDEWEB)

    Beaux II, Miles Frank [Los Alamos National Lab. (LANL), Los Alamos, NM (United States); Usov, Igor Olegovich [Los Alamos National Lab. (LANL), Los Alamos, NM (United States)

    2017-02-07

    Chemical vapor deposition (CVD) techniques have been utilized to produce free-standing molybdenum tubes with the end goal of nuclear fuel clad applications. In order to produce tubes with properties desirable for this application, deposition rates were lowered requiring long deposition durations on the order of 50 hours. Standard CVD methods as well as fluidized-bed CVD (FBCVD) methods were applied towards these objectives. Characterization of the tubes produced in this manner revealed material suitable for fuel clad applications, but lacking necessary uniformity across the length of the tubes. The production of freestanding Mo tubes that possess the desired properties across their entire length represents an engineering challenge that can be overcome in a next iteration of the deposition system.

  11. Wavy tube heat pumping

    Energy Technology Data Exchange (ETDEWEB)

    Haldeman, C. W.

    1985-12-03

    A PVC conduit about 4'' in diameter and a little more than 40 feet long is adapted for being seated in a hole in the earth and surrounds a coaxial copper tube along its length that carries Freon between a heat pump and a distributor at the bottom. A number of wavy conducting tubes located between the central conducting tube and the wall of the conduit interconnect the distributor with a Freon distributor at the top arranged for connection to the heat pump. The wavy conducting tubing is made by passing straight soft copper tubing between a pair of like opposed meshing gears each having four convex points in space quadrature separated by four convex recesses with the radius of curvature of each point slightly less than that of each concave recess.

  12. Shocks and Thermal Conduction Fronts in Retracting Reconnected Flux Tubes

    CERN Document Server

    Guidoni, Silvina

    2010-01-01

    We present a model for plasma heating produced by time-dependent, spatially localized reconnection within a flare current sheet separating skewed magnetic fields. The reconnection creates flux tubes of new connectivity which subsequently retract at Alfv\\'enic speeds from the reconnection site. Heating occurs in gas-dynamic shocks which develop inside these tubes. Here we present generalized thin flux tube equations for the dynamics of reconnected flux tubes, including pressure-driven parallel dynamics as well as temperature dependent, anisotropic viscosity and thermal conductivity. The evolution of tubes embedded in a uniform, skewed magnetic field, following reconnection in a patch, is studied through numerical solutions of these equations, for solar coronal conditions. Even though viscosity and thermal conductivity are negligible in the quiet solar corona, the strong gas-dynamic shocks generated by compressing plasma inside reconnected flux tubes generate large velocity and temperature gradients along the t...

  13. What Are Neural Tube Defects?

    Science.gov (United States)

    ... NICHD Research Information Clinical Trials Resources and Publications Neural Tube Defects (NTDs): Condition Information Skip sharing on social media links Share this: Page Content What are neural tube defects? Neural (pronounced NOOR-uhl ) tube defects are ...

  14. Polymeric endoaortic paving: Mechanical, thermoforming, and degradation properties of polycaprolactone/polyurethane blends for cardiovascular applications.

    Science.gov (United States)

    Ashton, J H; Mertz, J A M; Harper, J L; Slepian, M J; Mills, J L; McGrath, D V; Vande Geest, J P

    2011-01-01

    Polymeric endoaortic paving (PEAP) is a process by which a polymer is endovascularly delivered and thermoformed to coat or "pave" the lumen of the aorta. This method may offer an improvement to conventional endoaortic therapy in allowing conformal graft application with reduced risk of endoleak and customization to complex patient geometries. Polycaprolactone (PCL)/polyurethane (PU) blends of various blend ratios were assessed as a potential material for PEAP by characterizing their mechanical, thermoforming and degradation properties. Biaxial tension testing revealed that the blends' stiffness is similar to that of aortic tissue, is higher for blends with more PCL content, and may be affected by thermoforming and degradation. Tubes of blends were able to maintain a higher diameter increase after thermoforming at higher PCL content and higher heating temperatures; 50/50 blend tubes heated to 55 °C were able to maintain 90% of the diameter increase applied. Delamination forces of the blends ranged from 41 to 235 N m⁻². In a Pseudomonas lipase solution, the 50/50 blend had a 94% lower degradation rate than pure PCL, and the 10/90 blend exhibited no degradation. These results indicate that PEAP, consisting of a PCL/PU blend, may be useful in developing the next generation of endoaortic therapy.

  15. Counter-driver shock tube

    Science.gov (United States)

    Tamba, T.; Nguyen, T. M.; Takeya, K.; Harasaki, T.; Iwakawa, A.; Sasoh, A.

    2015-11-01

    A "counter-driver" shock tube was developed. In this device, two counter drivers are actuated with an appropriate delay time to generate the interaction between a shock wave and a flow in the opposite direction which is induced by another shock wave. The conditions for the counter drivers can be set independently. Each driver is activated by a separate electrically controlled diaphragm rupture device, in which a pneumatic piston drives a rupture needle with a temporal jitter of better than 1.1 ms. Operation demonstrations were conducted to evaluate the practical performance.

  16. Isolated Fallopian Tube Torsion

    Directory of Open Access Journals (Sweden)

    S. Kardakis

    2013-01-01

    Full Text Available Isolated torsion of the Fallopian tube is a rare gynecological cause of acute lower abdominal pain, and diagnosis is difficult. There are no pathognomonic symptoms; clinical, imaging, or laboratory findings. A preoperative ultrasound showing tubular adnexal masses of heterogeneous echogenicity with cystic component is often present. Diagnosis can rarely be made before operation, and laparoscopy is necessary to establish the diagnosis. Unfortunately, surgery often is performed too late for tube conservation. Isolated Fallopian tube torsion should be suspected in case of acute pelvic pain, and prompt intervention is necessary.

  17. Technical analysis of failure of catalyst support of reformer furnace tube of a hydrogen generation unit%制氢装置转化炉炉管催化剂支托失效分析

    Institute of Scientific and Technical Information of China (English)

    齐庆轩; 冯岩

    2012-01-01

    The damages of catalyst support of reformer furnace tubes of No. 1 hydrogen generation unit in SINOPEC Shijiazhuang Refining & Chemical Co. , Ltd. in two maintenances were introduced. The composition analysis of catalyst support, the study on the macroscopic photo, the analysis of damaged surface of catalyst support of Incoloy800H, the metallographic analysis, energy dispersion spectrum (EDS) analysis, and scanning electron microscope analysis of support' s section area as well as study on the anti-caburization performances of Cr25Ni20 and Incoloy800H materials have concluded the following: The damages of catalyst support was caused by surface carburization of catalyst support material under high temperature in the presence of hydrogen, which led to phase changes of material surface structure, material stratification, loosening and bulging of surface material structure, large amount of micro-crackings in grain boundary at surface area and eduction of large amount of carbides. All these will reduce the ductility and plasticity of material. Therefore, it is difficult for the catalyst support to restore its original state after thermal expansion, which explains why there are some bulges on the tube of failed support. The anti-carburization performance is greatly improved after application of Cr25Ni20 steel material.%对两次检修中所发现的中国石油化工股份有限公司石家庄炼化分公司l号制氢装置转化炉炉管催化剂支托出现损坏的情况做了介绍,并对两种批次的催化剂支托进行了成分分析,对使用Incoloy800H材料、损坏严重的催化剂支托表面宏观照片进行了分析,对损伤支托的横截面进行金相、电镜及能谱检验分析.通过对Cr25Ni20和lncoloy800H两种材料的抗渗碳能力的比较,得出了以下结论:催化剂支托损伤的原因是材料在含氢高温环境下发生了表面渗碳现象,直接导致材料表面组织相变、材料分层、表现材料组织疏松和隆起,

  18. Ca(II) doped β-In2S3 hierarchical structures for photocatalytic hydrogen generation and organic dye degradation under visible light irradiation.

    Science.gov (United States)

    Yang, Shuang; Xu, Cheng-Yan; Zhang, Bao-You; Yang, Li; Hu, Sheng-Peng; Zhen, Liang

    2017-04-01

    Hierarchical structures assembled by two-dimensional (2D) nanosheets could inherit the characteristics of nanosheets and acquire additional advantages from the unique secondary architectures, which would have important influences on the photocatalytic properties of semiconductor nanomaterials. In this work, we successfully synthesized Ca(II) doped β-In2S3 hierarchical structures stacked by thin nanosheets by a simple solution chemical process. The effects of reaction temperature and Ca(2+) concentration on the size and morphology of the products were systematically investigated. The photocatalytic applications of the β-In2S3 hierarchical structures were evaluated for hydrogen production and degradation of Rhodamine B (RhB) under visible light irradiation (λ>420nm). The β-In2S3 hierarchical structures showed promising activity towards photocatalytic hydrogen production (145.0μmolg(-1)h(-1)) and RhB solution (1×10(-5)M) was completely degraded within 100min under visible light irradiation.

  19. A long-term degradation study of power generation characteristics of anode-supported solid oxide fuel cells using LaNi(Fe)O{sub 3} electrode

    Energy Technology Data Exchange (ETDEWEB)

    Komatsu, Takeshi; Watanabe, Kimitaka; Arakawa, Masayasu; Arai, Hajime [NTT Corporation, NTT Energy and Environment Systems Laboratories, Morinosato-Wakamiya 3-1, Atsugi-shi, Kanagawa 243-0198 (Japan)

    2009-09-05

    The long-term operation of an anode-supported solid oxide fuel cell was examined to study the degradation factor. The cell was constructed using LaNi{sub 0.6}Fe{sub 0.4}O{sub 3} (LNF), alumina-doped scandia stabilized zirconia (SASZ), and NiO-SASZ as the cathode, electrolyte, and anode respectively. The cell had Pt current collectors and was operated for 6500 h. The test was carried out at 1073 K with a constant load of 0.4 A cm{sup -2} and included thermal cycling. The cell voltage degradation rate was below 0.86%/1000 h when the cell was operated for up to 5200 h. Changes in the resistance of the cells during the experiments were analyzed by impedance spectroscopy. The cathode polarization resistance and ohmic resistance increased with time. The elements (Si and B) contained in the water condensed from the cathode exhaust gas were identified using inductively coupled plasma (ICP). (author)

  20. Chest tube insertion - slideshow

    Science.gov (United States)

    ... presentations/100008.htm Chest tube insertion - series—Normal anatomy To use the sharing features ... pleural space is the space between the inner and outer lining of the lung. It is normally very thin, and lined only ...

  1. Snorkeling and Jones tubes

    OpenAIRE

    Lam, Lewis Y. W.; Weatherhead, Robert G.

    2015-01-01

    We report a case of tympanic membrane rupture during snorkeling in a 17-year-old young man who had previously undergone bilateral Jones tubes placed for epiphora. To our knowledge, this phenomenon has not been previously reported.

  2. Snorkeling and Jones tubes.

    Science.gov (United States)

    Lam, Lewis Y W; Weatherhead, Robert G

    2015-01-01

    We report a case of tympanic membrane rupture during snorkeling in a 17-year-old young man who had previously undergone bilateral Jones tubes placed for epiphora. To our knowledge, this phenomenon has not been previously reported.

  3. Nasogastric feeding tube

    Science.gov (United States)

    ... page: //medlineplus.gov/ency/patientinstructions/000182.htm Nasogastric feeding tube To use the sharing features on this ... the nose. It can be used for all feedings or for giving a person extra calories. It ...

  4. Ear tube insertion - slideshow

    Science.gov (United States)

    ... this page: //medlineplus.gov/ency/presentations/100045.htm Ear tube insertion - series—Normal anatomy To use the ... 4 Overview The eardrum (tympanic membrane) separates the ear canal from the middle ear. Review Date 8/ ...

  5. Kinking of medical tubes.

    Science.gov (United States)

    Ingles, David

    2004-05-01

    The phenomenon of kinking in medical tubing remains a problem for some applications, particularly critical ones such as transporting gasses or fluids. Design features are described to prevent its occurrence.

  6. Using a nasogastric tube.

    Science.gov (United States)

    Candy, C

    1986-09-01

    This discussion of the use of a nasogastric tube covers the equipment needed, the method, rehydration and feeding, prolonged nasogastric feeding, and stopping nasogastric feeding. A nasogastric tube is useful when children are unable to drink safely and in sufficient amounts for any of the following reasons: severe dehydration; if intravenous (IV) therapy is unavailable; low birth weight infants; or the child is drowsy or vomiting. Severely malnourished children may be fed initially in this way if they are too weak or anorexic to eat or drink normally. The following equipment is needed: nasogastric tube; lubricating fluid; a syringe; blue litmus paper, if available; adhesive tape; stethoscope if available; and fluid to be given. Explain to the child's parents and the child, if old enough to understand, what will be done; lie infants flat; measure the approximate length from the child's nostril to the ear lobe and then to the top of the abdomen with the tube and mark the position; clean the nostrils to remove the mucus, and lubricate the tip of the tube and gently insert into the nostril; give the child a drink of water if he or she is conscious; continue to pass the tube down until the position marked reaches the nostril; use the syringe to suck up some fluid and test with blue litmus paper to check that the tube is in the stomach; and inject 5-10 ml of fluid (saline or oral rehydration solution, not milk formula) by syringe if satisfied the tube is in the correct position. Where possible, give a continuous drip of fluid. If this is not possible, give frequent small amounts using the syringe as a funnel. If feeding continues for more than 24 hours, clean the nostrils daily with warm water and change the tube to the other nostril every few days. Also keep the mouth very clean with a dilute solution of 8% sodium bicarbonate, if available, or citrus fruit juice. To remove the tube, remove the adhesive tape, take the tube out gently and smoothly, and offer the child a

  7. Magnesium tube hydroforming

    Energy Technology Data Exchange (ETDEWEB)

    Liewald, M.; Pop, R. [Institute for Metal Forming Technology (IFU), Stuttgart (Germany)

    2008-04-15

    Magnesium alloys reveal a good strength-to-weight ratio in the family of lightweight metals and gains potential to provide up to 30% mass savings compared to aluminium and up to 75 % compared to steel. The use of sheet magnesium alloys for auto body applications is however limited due to the relatively low formability at room temperature. Within the scope of this paper, extruded magnesium tubes, which are suitable for hydroforming applications, have been investigated. Results obtained at room temperature using magnesium AZ31 tubes show that circumferential strains are limited to a maximal value of 4%. In order to examine the influence of the forming temperature on tube formability, investigations have been carried out with a new die set for hot internal high pressure (IHP) forming at temperatures up to 400 C. Earlier investigations with magnesium AZ31 tubes have shown that fractures occur along the welding line at tubes extruded over a spider die, whereby a non-uniform expansion at bursting with an elongation value of 24% can be observed. A maximum circumferential strain of approx. 60% could be attained when seamless, mechanically pre-expanded and annealed tubes of the same alloy have been used. The effect of annealing time on materials forming properties shows a fine grained structure for sufficient annealing times as well as deterioration with a large increase at same time. Hence, seamless ZM21 tubes have been used in the current investigations. With these tubes, an increased tensile fracture strain of 116% at 350 C is observed as against 19% at 20 C, obtained by tensile testing of milled specimens from the extruded tubes. This behaviour is also seen under the condition of tool contact during the IHP forming process. To determine the maximum circumferential strain at different forming temperatures and strain rates, the tubes are initially bulged in a die with square cross-section under plane stress conditions. Thereafter, the tubes are calibrated by using an

  8. 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,

  9. Ten Years of Shock Tube Research at Marseille

    Science.gov (United States)

    Houas, L.

    The invention of the shock tube is attributed to Paul Vieille [1] in the late 19th century. The first simplest shock tube was composed of two chambers separated by a diaphragm.With the pressure increase in the first chamber causing the diaphragm rupture, a shock wave was generated and propagated with a supersonic velocity in the second chamber.

  10. Improvement of the corrosion resistance by using enamel coating applied to the carbon steel fin tubes of the HRSG

    Energy Technology Data Exchange (ETDEWEB)

    Kim, Won Seok; Lee, Jong Wook [BHI, Haman (Korea, Republic of)

    2014-07-15

    Gas side corrosion affects all heat recovery steam generators (HRSGs). Consequences range from unsightliness and reduced performance to reliability problems and potential safety hazards. The enamel coating used for the HRSG fin tubes was visually and microscopically inspected, analyzed and compared with original one. From the results of the analysis, there was not much different between the coating and the original in the comparison of the strength, SEM (scanning electron microscope), and thermal expansion. For the overall heat transfer due to the coating, it was found that the coating fin tubes have about 2% degradation in comparison with the original ones. However, the use of enamel coating can help strongly to delay the corrosion problem by flue gases in the HRSG.

  11. 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.

  12. Dynamic tube/support interaction in heat exchanger tubes

    Energy Technology Data Exchange (ETDEWEB)

    Chen, S.S.

    1991-01-01

    The supports for heat exchanger tubes are usually plates with drilled holes; other types of supports also have been used. To facilitate manufacture and to allow for thermal expansion of the tubes, small clearances are used between tubes and tube supports. The dynamics of tube/support interaction in heat exchangers is fairly complicated. Understanding tube dynamics and its effects is important for heat exchangers. This paper summarizes the current state of the art on this subject and to identify future research needs. Specifically, the following topics are discussed: dynamics of loosely supported tubes, tube/support gap dynamics, tube response in flow, tube damage and wear, design considerations, and future research needs. 55 refs., 1 fig.

  13. Viability of use of PVC tubes in solar collectors: an analysis of materials

    Directory of Open Access Journals (Sweden)

    Luiz Guillherme Meira de Souza

    2003-06-01

    Full Text Available This paper presents a study of the inherent degradations of PVC tubes due to the thermal effect and ultraviolet solar radiation. The approach relates its causes and its effect of use of the PVC tubes as elements to absorption, forming a coil, in solar collectors for water heating. It is demonstrated that such degradations can be burst through the use of an outflow and an appropriate regimen of work, as well as of a protective layer for the tubes, in this case black ink used to magnify its absorption. The results of the properties of tubes that had been exposed to the degradation effect for up to five years are presented. The viability of use of this type of collector is demonstrated through comparative analysis of tubes exposed and not exposed to the sun, concluding for the low cost, easy assembly and maintenance of the system.

  14. Flow induced pulsations caused by corrugated tubes

    NARCIS (Netherlands)

    Shatto, D.P.; Belfroid, S.P.C.; Peters, M.C.A.M.

    2007-01-01

    Corrugated tubes can produce a tonal noise when used for gas transport, for instance in the case of flexible risers. The whistling sound is generated by shear layer instability due to the boundary layer separation at each corrugation. This whistling is examined by investigating the frequency, amplit

  15. Demonstration for the Applicability of the EPRI ETSS on the SG Tube Wear Defects Formed at the Tube Support Structure

    Energy Technology Data Exchange (ETDEWEB)

    Shin, Ki Seok; Cheon, Keun Young; Nam, Min Woo [Korea Hydro and Nuclear Power Co. Ltd, Daejeon (Korea, Republic of); Min, Kyong Mahn [Universal Monitoring and Inspection Inc., Daejeon (Korea, Republic of)

    2013-10-15

    In this paper, the authorized EPRI ETSS 27906.2 applied to the detection of tapered wear volumetric indications and depth sizing within the free span area, loose part not present was reviewed and applied to the site SG tubes for getting the actual value of the wear depth and providing structural integrity interpretation based on engineering evaluation. The experiment to demonstrate the applicability of EPRI ETSS was performed by the employment of the newly prepared STD tube and resulted in ensuring the effectiveness and equivalency of the EPRI ETSS as well. The authorized EPRI ETSS 27906.2 for getting the actual value of the wear depth and providing structural integrity interpretation based on engineering evaluation was reviewed and applied to the site SG tubes. The testing results were reviewed with the influences of SG tube material and the support structure. The impact of the tube materials was insignificant and that of the tube support structure showed somewhat conservative results. The testing resulted in successful demonstration of applicability of the EPRI ETSS on the SG tube wear defects at the tube support. One of the major flaw mechanisms detected in the currently operating domestic OPR-1000 pressurized water reactors(PWR's) steam generator(SG) tubes is wear defect. In general, wear defect has been constantly detected in the upper tube bundle imposed to the flow induced vibration interaction between tube and its support structure, and the quantity of the affected tubes has also shown the tendency to increase as plant operation life is added. In order to take appropriate measures and maintain the structural integrity for the SG tubes, wear defect is currently categorized as active damage mechanism and the tubes containing 40% or greater wear depth of the nominal tube wall thickness shall be plugged per SGMP(SG Management Program) Recently, a fairly large amplitude of wear defects on the Batwing(BW), one of the upper tube support structures in the SG

  16. Enhancing reactive species generation upon photo-activation of CdTe quantum dots for the chemiluminometric determination of unreacted reagent in UV/S2O8(2-) drug degradation process.

    Science.gov (United States)

    Santana, Rodolfo M M; Oliveira, Thaís D; Rodrigues, S Sofia M; Frigerio, Christian; Santos, João L M; Korn, Mauro

    2015-04-01

    A new chemiluminescence (CL) flow method for persulfate determination was developed based on luminol oxidation by in-line generated radicals. Reactive oxygen species (ROS) generated by CdTe quantum dots (QDs) under a low energetic radiation (visible light emitted by LEDs) promoted the decomposition of persulfate ion (S2O8(2-)) into sulfate radical (SO4(∙-)), leading to subsequent radical chain reactions that yield the emission of light. Due to the inherent radical short lifetimes and the transient behavior of CL phenomena an automated multi-pumping flow system (MPFS) was proposed to improve sample manipulation and reaction zone implementation ensuring reproducible analysis time and high sampling rate. The developed approach allowed up to 60 determinations per hour and determine S2O8(2-) concentrations between 0.1 and 1 mmol with good linearity (R=0.9999). The method has shown good repeatability with relative standard deviations below 2.5% (n=3) for different persulfate concentrations (0.1 and 0.625 mmol L(-1)). Limits of detection (3σ) and quantification (10σ) were 2.7 and 9.1 µmol L(-1), respectively. The MPFS system was applied to persulfate determination in bench scale UV/S2O8(2-) drug degradation processes of model samples showing good versatility and providing real time information on the persulfate consumption in photo-chemical degradation methodologies.

  17. A comparison of the heat transfer and pressure drop performance of R-134a-lubricant mixtures in different diameter smooth tubes and micro-fin tubes

    Energy Technology Data Exchange (ETDEWEB)

    Eckels, S.J. [Kansas State Univ., Manhattan, KS (United States). Dept. of Mechanical Engineering; Doerr, T.M.; Pate, M.B. [Iowa State Univ., Ames, IA (United States). Mechanical Engineering Dept.

    1998-10-01

    The average heat transfer coefficients and pressure drops during evaporation and condensation are reported for mixtures of R-134a and an ester lubricant in tubes of 12.7 mm (1/2 in.) outer diameter. The objective of this paper is to evaluate the performance of the R-134a-lubricant mixtures in these tubes and determine the performance benefits of the micro-fin tube. The performance benefits of the tubes with 12.7 mm (1/2 in.) outer diameter are compared to those of smaller tubes with 9.52 mm (3/8 in.) outer diameter. The lubricant used was a 169 SUS penta erythritol ester mixed-acid lubricant. The lubricant concentration was varied from 0--5.1% in the mixture. The average heat transfer coefficients in the 12.7 mm (1/2 in.) micro-fin tube were 50--150% higher than those for the 12.7 mm (1/2 in.) smooth tube, while pressure drops in the micro-fin tube were 5% to 50% higher than in the smooth tube. The addition of lubricant degraded the average heat transfer coefficients in all cases except during evaporation at low lubricant concentrations. Pressure drops were always increased with the addition of lubricant. The experimental results also indicate that tube diameter has some effect on the performance benefits of the micro-fin tube over that of the smooth tube.

  18. NEI You Tube Videos: Amblyopia

    Medline Plus

    Full Text Available ... search for current job openings visit HHS USAJobs Home > NEI YouTube Videos > NEI YouTube Videos: Amblyopia NEI YouTube Videos YouTube Videos Home Age-Related Macular Degeneration Amblyopia Animations Blindness Cataract ...

  19. 4' and 24' Shock Tubes - Electric Arc Shock Tube Facililty N-229 (East) The facility is used to

    Science.gov (United States)

    1978-01-01

    4' and 24' Shock Tubes - Electric Arc Shock Tube Facililty N-229 (East) The facility is used to investigate the effects of radiation and ionization during outer planetary entries as well as for air-blast simualtion which requires the strongest possible shock generation in air at loadings of 1 atm or greater.

  20. Recent operating experiences with steam generators in Japanese NPPs

    Energy Technology Data Exchange (ETDEWEB)

    Yashima, Seiji [Japan Power Engineering and Inspection Corp., Tokyo (Japan)

    1997-02-01

    In 1994, the Genkai-3 of Kyushu Electric Power Co., Inc. and the Ikata-3 of Shikoku Electric Power Co., Inc. started commercial operation, and now 22 PWR plants are being operated in Japan. Since the first PWR plant now 22 PWR plants are being operated in was started to operate, Japanese PWR plants have had an operating experience of approx. 280 reactor-years. During that period, many tube degradations have been experienced in steam generators (SGs). And, in 1991, the steam generator tube rupture (SGTR) occurred in the Mihama-2 of Kansai Electric Power Co., Inc. However, the occurrence of tube degradation of SGs has been decreased by the instructions of the MITI as regulatory authorities, efforts of Electric Utilities, and technical support from the SG manufacturers. Here the author describes the recent SGs in Japan about the following points. (1) Recent Operating Experiences (2) Lessons learned from Mihama-2 SGTR (3) SG replacement (4) Safety Regulations on SG (5) Research and development on SG.

  1. Deformation and degradation of polymers in ultra-high-pressure liquid chromatography.

    Science.gov (United States)

    Uliyanchenko, Elena; van der Wal, Sjoerd; Schoenmakers, Peter J

    2011-09-28

    Ultra-high-pressure liquid chromatography (UHPLC) using columns packed with sub-2 μm particles has great potential for separations of many types of complex samples, including polymers. However, the application of UHPLC for the analysis of polymers meets some fundamental obstacles. Small particles and narrow bore tubing in combination with high pressures generate significant shear and extensional forces in UHPLC systems, which may affect polymer chains. At high stress conditions flexible macromolecules may become extended and eventually the chemical bonds in the molecules can break. Deformation and degradation of macromolecules will affect the peak retention and the peak shape in the chromatogram, which may cause errors in the obtained results (e.g. the calculated molecular-weight distributions). In the present work we explored the limitations of UHPLC for the analysis of polymers. Degradation and deformation of macromolecules were studied by collecting and re-injecting polymer peaks and by off-line two-dimensional liquid chromatography. Polystyrene standards with molecular weight of 4 MDa and larger were found to degrade at UHPLC conditions. However, for most polymers degradation could be avoided by using low linear velocities. No degradation of 3-MDa PS (and smaller) was observed at linear velocities up to 7 mm/s. The column frits were implicated as the main sources of polymer degradation. The extent of degradation was found to depend on the type of the column and on the column history. At high flow rates degradation was observed without a column being installed. We demonstrated that polymer deformation preceded degradation. Stretched polymers eluted from the column in slalom chromatography mode (elution order opposite to that in SEC or HDC). Under certain conditions we observed co-elution of large and small PS molecules though a convolution of slalom chromatography and hydrodynamic chromatography.

  2. Template synthesized chitosan nano test tubes for drug delivery applications

    Science.gov (United States)

    Perry, Jillian L. Moulton

    (glutathione) found within cells. Therefore, once the nano test tubes reach their target site and are taken into a cell, the tubes can be degraded and release their payload. This chitosan nano test tube delivery stystem shows great potential for applications in targeted drug delivery. (Full text of this dissertation may be available via the University of Florida Libraries web site. Please check http://www.uflib.ufl.edu/etd.html)

  3. Experimental study on a simple Ranque Hilsch vortex tube

    Science.gov (United States)

    Gao, C. M.; Bosschaart, K. J.; Zeegers, J. C. H.; de Waele, A. T. A. M.

    2005-03-01

    The Ranque-Hilsch vortex tube is a device by which cold gas can be generated using compressed gas. To understand the cooling mechanism of this device, it is necessary to know the pressure, temperature, and velocity distributions inside the tube. In order to investigate this, a simple vortex tube is built and nitrogen is used as its working fluid. A special Pitot tube is used for the measurement of the pressure and velocity. This Pitot tube consists of a capillary which has only one hole in the cylinder wall. With this Pitot tube, the pressure and velocity fields inside the tube were measured. In the same way, the temperature field was measured with a thermocouple. The results of three different entrance conditions are compared here. With the measurements results, the analysis based on the two thermodynamic laws has been made. It is found that rounding off the entrance has influence on the performance of the vortex tube. The secondary circulation gas flow inside the vortex tube can be enhanced and enlarged, the performance of the Ranque-Hilsch vortex tube improved.

  4. Ablation of Arg-tRNA-protein transferases results in defective neural tube development.

    Science.gov (United States)

    Kim, Eunkyoung; Kim, Seonmu; Lee, Jung Hoon; Kwon, Yong Tae; Lee, Min Jae

    2016-08-01

    The arginylation branch of the N-end rule pathway is a ubiquitin-mediated proteolytic system in which post-translational conjugation of Arg by ATE1-encoded Arg-tRNA-protein transferase to N-terminal Asp, Glu, or oxidized Cys residues generates essential degradation signals. Here, we characterized the ATE1-/- mice and identified the essential role of N-terminal arginylation in neural tube development. ATE1-null mice showed severe intracerebral hemorrhages and cystic space near the neural tubes. Expression of ATE1 was prominent in the developing brain and spinal cord, and this pattern overlapped with the migration path of neural stem cells. The ATE1-/- brain showed defective G-protein signaling. Finally, we observed reduced mitosis in ATE1-/- neuroepithelium and a significantly higher nitric oxide concentration in the ATE1-/- brain. Our results strongly suggest that the crucial role of ATE1 in neural tube development is directly related to proper turn-over of the RGS4 protein, which participate in the oxygen-sensing mechanism in the cells. [BMB Reports 2016; 49(8): 443-448].

  5. Analysis of phase noise and cnr degradation of externally generated lo signal in lnb for ku-band dvb-s systems by heterodyning two lasers

    NARCIS (Netherlands)

    Khan, M.R.H.; Burla, M.; Roeloffzen, C.G.H.; Marpaung, D.A.I.; Etten, van W.

    2009-01-01

    We investigate the externally generation of an LO signal by optical heterodyning, which is then distributed to each of the mixers at every antenna element of a phased array antenna used for standard DVB-S (digital Video Broadcasting-Satellite) reception system. The system1 is presented in Figure 1.

  6. Pollen tube reuses intracellular components of nucellar cells undergoing programmed cell death in Pinus densiflora.

    Science.gov (United States)

    Hiratsuka, Rie; Terasaka, Osamu

    2011-04-01

    Through the process known as programmed cell death (PCD), nucelli of Pinus densiflora serve as the transmitting tissue for growth of the pollen tube. We sought to clarify the processes of degradation of nucellar cell components and their transport to the pollen tube during PCD in response to pollen tube penetration of such nucelli. Stimulated by pollination, synthesis of large amounts of starch grains occurred in cells in a wide region of the nucellus, but as the pollen tube penetrated the nucellus, starch grains were degraded in amyloplasts of nucellar cells. In cells undergoing PCD, electron-dense vacuoles with high membrane contrast appeared, assumed a variety of autophagic structures, expanded, and ultimately collapsed and disappeared. Vesicles and electron-dense amorphous materials were released inside the thickened walls of cells undergoing PCD, and those vesicles and materials reaching the pollen tube after passing through the extracellular matrix were taken into the tube by endocytosis. These results show that in PCD of nucellar cells, intracellular materials are degraded in amyloplasts and vacuoles, and some of the degraded material is supplied to the pollen tube by vesicular transport to support tube growth.

  7. 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.

  8. Effect of temperature distribution of thermal buffer tube on onset temperature in a straight-tube-type thermoacoustic prime mover

    Science.gov (United States)

    Wada, Takahiro; Sakamoto, Shin-ichi; Orino, Yuichiro; Ueno, So; Kajiura, Yuma

    2017-07-01

    We investigated a thermoacoustic system to achieve low-temperature driving. Inputting heat to the stack causes unwanted heat flows through the tube wall and the working gas, i.e., heat leak. The heat leak generates the temperature distribution along the tube from the high-temperature side of the stack to the closed end. The section where the temperature distribution is formed is called the thermal buffer tube. In this study, we focused on the temperature distribution of the thermal buffer tube. We measured the temperature distribution of the thermal buffer tube and made a comparison between the onset temperature obtained from the experiment and the critical temperature obtained by stability analysis. The difference in the results was 6 °C. The analytical critical temperature changed significantly with the assumed shape of the temperature distribution in the thermal buffer tube.

  9. Tracheostomy tubes and related appliances.

    Science.gov (United States)

    Hess, Dean R

    2005-04-01

    Tracheostomy tubes are used to administer positive-pressure ventilation, to provide a patent airway, to provide protection from aspiration, and to provide access to the lower respiratory tract for airway clearance. They are available in a variety of sizes and styles, from several manufacturers. The dimensions of tracheostomy tubes are given by their inner diameter, outer diameter, length, and curvature. Differences in length between tubes of the same inner diameter, but from different manufacturers, are not commonly appreciated but may have important clinical implications. Tracheostomy tubes can be angled or curved, a feature that can be used to improve the fit of the tube in the trachea. Extra proximal length tubes facilitate placement in patients with large necks, and extra distal length tubes facilitate placement in patients with tracheal anomalies. Several tube designs have a spiral wire reinforced flexible design and have an adjustable flange design to allow bedside adjustments to meet extra-length tracheostomy tube needs. Tracheostomy tubes can be cuffed or uncuffed. Cuffs on tracheostomy tubes include high-volume low-pressure cuffs, tight-to-shaft cuffs, and foam cuffs. The fenestrated tracheostomy tube has an opening in the posterior portion of the tube, above the cuff, which allows the patient to breathe through the upper airway when the inner cannula is removed. Tracheostomy tubes with an inner cannula are called dual-cannula tracheostomy tubes. Several tracheostomy tubes are designed specifically for use with the percutaneous tracheostomy procedure. Others are designed with a port above the cuff that allows for subglottic aspiration of secretions. The tracheostomy button is used for stoma maintenance. It is important for clinicians caring for patients with a tracheostomy tube to understand the nuances of various tracheostomy tube designs and to select a tube that appropriately fits the patient.

  10. Development and quality assessments of commercial heat production of ATF FeCrAl tubes

    Energy Technology Data Exchange (ETDEWEB)

    Yamamoto, Yukinori [Oak Ridge National Lab. (ORNL), Oak Ridge, TN (United States)

    2015-09-01

    Development and quality assessment of the 2nd generation ATF FeCrAl tube production with commercial manufacturers were conducted. The manufacturing partners include Sophisticated Alloys, Inc. (SAI), Butler, PA for FeCrAl alloy casting via vacuum induction melting, Oak Ridge National Laboratory (ORNL) for extrusion process to prepare the master bars/tubes to be tube-drawn, and Rhenium Alloys, Inc. (RAI), North Ridgeville, OH, for tube-drawing process. The masters bars have also been provided to Los Alamos National Laboratory (LANL) who works with Century Tubes, Inc., (CTI), San Diego, CA, as parallel tube production effort under the current program.

  11. A vacuum-sealed miniature X-ray tube based on carbon nanotube field emitters

    Science.gov (United States)

    Heo, Sung Hwan; Kim, Hyun Jin; Ha, Jun Mok; Cho, Sung Oh

    2012-05-01

    A vacuum-sealed miniature X-ray tube based on a carbon nanotube field-emission electron source has been demonstrated. The diameter of the X-ray tube is 10 mm; the total length of the tube is 50 mm, and no external vacuum pump is required for the operation. The maximum tube voltage reaches up to 70 kV, and the X-ray tube generates intense X-rays with the air kerma strength of 108 Gy·cm2 min-1. In addition, X-rays produced from the miniature X-ray tube have a comparatively uniform spatial dose distribution.

  12. A vacuum-sealed miniature X-ray tube based on carbon nanotube field emitters

    OpenAIRE

    Heo, Sung Hwan; Kim, Hyun Jin; Ha, Jun Mok; Cho, Sung Oh

    2012-01-01

    A vacuum-sealed miniature X-ray tube based on a carbon nanotube field-emission electron source has been demonstrated. The diameter of the X-ray tube is 10 mm; the total length of the tube is 50 mm, and no external vacuum pump is required for the operation. The maximum tube voltage reaches up to 70 kV, and the X-ray tube generates intense X-rays with the air kerma strength of 108 Gy·cm2 min−1. In addition, X-rays produced from the miniature X-ray tube have a comparatively uniform spatial dose ...

  13. Annihilation and Reanimation of a Tornado in the Improved Tornado Tube

    Science.gov (United States)

    Bednarek, Stanislaw

    2016-01-01

    Some new experiments using an improved version of the "tornado tube" are described here. The improved tornado tube consists of two plastic transparent bottles whose openings are connected with a ball valve, available at most hardware stores. After being filled with fluid and inverting, this tube allows demonstration of the generation,…

  14. Heat transfer in a gray tube with forced convection, internal radiation and axial wall conduction

    Science.gov (United States)

    Chung, B. T. F.; Thompson, J. E.

    1983-01-01

    A method of successive approximations is employed to solve the problem of heat transfer to a transparent gas flowing through a radiating-conducting tube with turbulent forced convection between the tube wall and the gas, and with energy generation in the wall. Emphasis is given to the effect of emissivity of the wall to the tube and gas temperature profiles.

  15. Annihilation and Reanimation of a Tornado in the Improved Tornado Tube

    Science.gov (United States)

    Bednarek, Stanislaw

    2016-01-01

    Some new experiments using an improved version of the "tornado tube" are described here. The improved tornado tube consists of two plastic transparent bottles whose openings are connected with a ball valve, available at most hardware stores. After being filled with fluid and inverting, this tube allows demonstration of the generation,…

  16. PE on YouTube--Investigating Participation in Physical Education Practice

    Science.gov (United States)

    Quennerstedt, Mikael

    2013-01-01

    Background: In this article, students' diverse ways of participating in physical education (PE) practice shown in clips on YouTube were investigated. YouTube is the largest user-generated video-sharing website on the Internet, where different video content is presented. The clips on YouTube, as used in this paper, can be seen as a user-generated…

  17. Premixed flame propagation in vertical tubes

    Science.gov (United States)

    Kazakov, Kirill A.

    2016-04-01

    Analytical treatment of the premixed flame propagation in vertical tubes with smooth walls is given. Using the on-shell flame description, equations for a quasi-steady flame with a small but finite front thickness are obtained and solved numerically. It is found that near the limits of inflammability, solutions describing upward flame propagation come in pairs having close propagation speeds and that the effect of gravity is to reverse the burnt gas velocity profile generated by the flame. On the basis of these results, a theory of partial flame propagation driven by a strong gravitational field is developed. A complete explanation is given of the intricate observed behavior of limit flames, including dependence of the inflammability range on the size of the combustion domain, the large distances of partial flame propagation, and the progression of flame extinction. The role of the finite front-thickness effects is discussed in detail. Also, various mechanisms governing flame acceleration in smooth tubes are identified. Acceleration of methane-air flames in open tubes is shown to be a combined effect of the hydrostatic pressure difference produced by the ambient cold air and the difference of dynamic gas pressure at the tube ends. On the other hand, a strong spontaneous acceleration of the fast methane-oxygen flames at the initial stage of their evolution in open-closed tubes is conditioned by metastability of the quasi-steady propagation regimes. An extensive comparison of the obtained results with the experimental data is made.

  18. Mechanical properties of ceramic composite tubes

    Energy Technology Data Exchange (ETDEWEB)

    Curtin, W.A.; Oleksuk, L.L.; Reifsnider, K.L. [Virginia Polytechnic Inst. and State Univ., Blacksburg, VA (United States); Stinton, D.P. [Oak Ridge National Lab., TN (United States)

    1995-08-01

    Results of axial tension tests on SiC/SiC tubular ceramic composite components fabricated by a forced-M technique are presented. Axial elastic modulus measurements on a number of tubes show that the Young`s modulus varies along the length of the tube, with occasional very stiff or very soft regions. Tests to failure on a few tubes show the initiation of non-linear stress-strain behavior to be in the range of 3-9 ksi, followed by extensive non-linear deformation up to failure. For one tube, the failure stress obtained was 20.1 ksi, but the strains to failure at various axial locations varies from 0.19%to 0.24%. The correlation between modulus and proportional limit is considered within the ACK matrix cracking theory and within a model in which matrix cracking between fiber tows occurs, both modified to account for matrix porosity. The crack size required to cause stress concentrations large enough to cause failure at the observed strength is considered. Predictions for both matrix cracking and strength suggest that the current generation of tubes are controlled by microstructural defects.

  19. Heat-shrink plastic tubing seals joints in glass tubing

    Science.gov (United States)

    Del Duca, B.; Downey, A.

    1968-01-01

    Small units of standard glass apparatus held together by short lengths of transparent heat-shrinkable polyolefin tubing. The tubing is shrunk over glass O-ring type connectors having O-rings but no lubricant.

  20. Review of EPRI's steam generator R and D program

    Energy Technology Data Exchange (ETDEWEB)

    Millett, P.J.; Welty, C.J. [EPRI, Palo Alto, CA (United States)

    1998-07-01

    EPRI has carried out an extensive R and D program on SG technology since the mid 1970's. Very early efforts under the auspices of the Steam Generator Owners Group (SGOG) focused on developing remedial actions for the critical SG corrosion issues of denting, wastage and pitting. Fundamental work was also carried out in the development of thermal hydraulic models for vibration and wear, chemical cleaning and tube repair techniques. In the late 1980's and continuing through today, the program has shifted emphasis towards management of steam generator degradation, primarily stress corrosion cracking of the SG tubes on both the primary and secondary sides. The current Steam Generator Management Program (SGMP) carries out R and D in four areas; materials, chemistry, thermal hydraulics and non-destructive testing. The strategic goals of this program and projects put in place to achieve these goals will be reviewed in detail in this paper. (author)

  1. Downhole pulse tube refrigerators

    Energy Technology Data Exchange (ETDEWEB)

    Swift, G.; Gardner, D. [Los Alamos National Lab., NM (United States). Condensed Matter and Thermal Physics Group

    1997-12-01

    This report summarizes a preliminary design study to explore the plausibility of using pulse tube refrigeration to cool instruments in a hot down-hole environment. The original motivation was to maintain Dave Reagor`s high-temperature superconducting electronics at 75 K, but the study has evolved to include three target design criteria: cooling at 30 C in a 300 C environment, cooling at 75 K in a 50 C environment, cooling at both 75 K and 30 C in a 250 C environment. These specific temperatures were chosen arbitrarily, as representative of what is possible. The primary goals are low cost, reliability, and small package diameter. Pulse-tube refrigeration is a rapidly growing sub-field of cryogenic refrigeration. The pulse tube refrigerator has recently become the simplest, cheapest, most rugged and reliable low-power cryocooler. The authors expect this technology will be applicable downhole because of the ratio of hot to cold temperatures (in absolute units, such as Kelvin) of interest in deep drilling is comparable to the ratios routinely achieved with cryogenic pulse-tube refrigerators.

  2. The thermal tube

    Energy Technology Data Exchange (ETDEWEB)

    Semena, M.G.

    1980-08-30

    A thermal tube is proposed which contains a layer of dielectric, capillary porous material located on the internal surface of the body. To increase the heat transmitting capability, the layer of capillary porous material is made in the form of a felting, formed by hollow fibers from a non-alkaline, borosilicate glass.

  3. 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,

  4. Cladding tube manufacturing technology

    Energy Technology Data Exchange (ETDEWEB)

    Hahn, R. [Kraftwerk Union AG, Mulheim (Germany); Jeong, Y.H.; Baek, B.J.; Kim, K.H.; Kim, S.J.; Choi, B.K.; Kim, J.M. [Korea Atomic Energy Research Institute, Taejon (Korea, Republic of)

    1999-04-01

    This report gives an overview of the manufacturing routine of PWR cladding tubes. The routine essentially consists of a series of deformation and annealing processes which are necessary to transform the ingot geometry to tube dimensions. By changing shape, microstructure and structure-related properties are altered simultaneously. First, a short overview of the basics of that part of deformation geometry is given which is related to tube reducing operations. Then those processes of the manufacturing routine which change the microstructure are depicted, and the influence of certain process parameters on microstructure and material properties are shown. The influence of the resulting microstructure on material properties is not discussed in detail, since it is described in my previous report 'Alloy Development for High Burnup Cladding.' Because of their paramount importance still up to now, and because manufacturing data and their influence on properties for other alloys are not so well established or published, the descriptions are mostly related to Zry4 tube manufacturing, and are only in short for other alloys. (author). 9 refs., 46 figs.

  5. Misdirected Minitracheostomy Tube

    Science.gov (United States)

    Singh, Ajmer; Nanda, Chinmaya; Mehta, Yatin

    2017-01-01

    We report a patient who after an uneventful coronary artery bypass graft surgery and left ventricular aneurysmorrhaphy developed intracerebral hemorrhage and subsequently required minitracheostomy. Chest X-ray showed misdirected minitracheostomy tube facing upward toward the laryngeal opening which was repositioned using bronchoscope. PMID:28074805

  6. Misdirected minitracheostomy tube

    Directory of Open Access Journals (Sweden)

    Ajmer Singh

    2017-01-01

    Full Text Available We report a patient who after an uneventful coronary artery bypass graft surgery and left ventricular aneurysmorrhaphy developed intracerebral hemorrhage and subsequently required minitracheostomy. Chest X-ray showed misdirected minitracheostomy tube facing upward toward the laryngeal opening which was repositioned using bronchoscope.

  7. Forced Convective Condensation of Nonazeotropic Refrigerant Mixtures in Horizontal Annulus with Petal Shaped Fin Tubes

    Institute of Scientific and Technical Information of China (English)

    WangShiping; ZhouXinqiu; 等

    1995-01-01

    In this paper,condensation performance in horizontal annulus was compared with a smooth tube,one Saw-Tooth Finned tube(STF tube),four Petal Shaped Fin tubes(PF tubes),using R113,R11 and their mixtures(vapor molar fractions of R11 at the test section inlet were 0.384,0.588and 0.809) as working fluid.The mass flux at the test section ranged from 15-220/m2s。Camera and video camera were used to shoot the flow pattern and condensation phenomena.The condensation transfer coefficient(hc) of mixtures were considerably lower than those of pure fluid,and did not change linearly with composition.The maximum degradation of measured hc from the ideal value were 23% for the smooth tube,65%for STF tube,67% for PF tubes,which occurred in the composition range of 0.4-0.6 vapor molar fraction of R11.For the condensation of mixture,R11 molar fraction from 38%to 81%,the PF tubes had the highest value of hc.which were 10-25% higher than those of STF tubes,and 480-580% higher than that of smooth tube,because the petal shaped fins of PF tubes could promote strong turbulence in the two phase flow,and reduce the mass transfer resistance.

  8. Radiological assessment of steam generator repair and replacement

    Energy Technology Data Exchange (ETDEWEB)

    Parkhurst, M.A.; Rathbun, L.A.; Murphy, D.W.

    1983-12-01

    Previous analyses of the radiological impact of removing and replacing corroded steam generators have been updated based on experience at Surry Units 1 and 2 and Turkey Point Units 3 and 4. The sleeving repairs of degraded tubes at San Onofre Unit 1, Point Beach Unit 2, and R.E. Ginna are also analyzed. Actual occupational doses incurred during application of the various technologies used in repairs have been included, along with radioactive waste quantities and constituents. Considerable progress has been made in improving radiation protection and reducing worker dose by the development of remotely controlled equipment and the implementation of dose reduction strategies that have been successful in previous repair operations.

  9. Polymeric Endoaortic Paving (PEAP): Mechanical, Thermoforming, and Degradation Properties of Polycaprolactone/Polyurethane Blends for Cardiovascular Applications

    Science.gov (United States)

    Ashton, John H.; Mertz, James A. M.; Harper, John L.; Slepian, Marvin J.; Mills, Joseph L.; McGrath, Dominic V.; Vande Geest, Jonathan P.

    2010-01-01

    Polymeric endoaortic paving (PEAP) is a process by which a polymer is endovascularly delivered and thermoformed to coat or “pave” the lumen of the aorta. This method may offer an improvement to conventional endoaortic therapy in allowing conformal graft application with reduced risk of endoleak and customization to complex patient geometries. Polycaprolactone (PCL)/polyurethane (PU) blends of various blend ratios were assessed as a potential material for PEAP by characterizing their mechanical, thermoforming, and degradation properties. Biaxial tension testing revealed that the blends' stiffness is similar to that of aortic tissue, is higher for blends with more PCL content, and may be affected by thermoforming and degradation. Tubes of blends were able to maintain a higher diameter increase after thermoforming at higher PCL content and higher heating temperatures; 50/50 blend tubes heated to 55°C were able to maintain 90% of the diameter increase applied. Delamination forces of the blends ranged from 41 to 235 N/m2. In a Pseudomonas lipase solution, the 50/50 blend had a 94% lower degradation rate than pure PCL, and the 10/90 blend exhibited no degradation. These results indicate that PEAP, consisting of a PCL/PU blend, may be useful in developing the next generation of endoaortic therapy. PMID:20832506

  10. Restore condition of Incore thimble tubes in guide tubes

    Energy Technology Data Exchange (ETDEWEB)

    Solanas, A.; Izquierdo, J.

    2014-07-01

    Aging of Nuclear Power Plant and succession of outages lead to wear and twist of the thimbles tubes but also to the fooling of Incore guide tubes. These can create friction and a high strength must be used for thimble tubes withdrawal. (Author)

  11. Eustachian tube function in children after insertion of ventilation tubes.

    NARCIS (Netherlands)

    Heerbeek, N. van; Ingels, K.J.A.O.; Snik, A.F.M.; Zielhuis, G.A.

    2001-01-01

    This study was performed to assess the effect of the insertion of ventilation tubes and the subsequent aeration of the middle ear on eustachian tube (ET) function in children. Manometric ET function tests were performed repeatedly for 3 months after the placement of ventilation tubes in 83 children

  12. Contribution of ethylamine degrading bacteria to atrazine degradation in soils.

    Science.gov (United States)

    Smith, Daniel; Crowley, David E

    2006-11-01

    Bacterial communities that cooperatively degrade atrazine commonly consist of diverse species in which the genes for atrazine dechlorination and dealkylation are variously distributed among different species. Normally, the first step in degradation of atrazine involves dechlorination mediated by atzA, followed by stepwise dealkylation to yield either N-ethylammelide or N-isopropylammelide. As the liberated alkylamine moieties are constituents of many organic molecules other than atrazine, it is possible that a large number of alkylamine-degrading bacteria other than those previously described might contribute to this key step in atrazine degradation. To examine this hypothesis, we isolated 82 bacterial strains from soil by plating soil water extracts on agar media with ethylamine as a sole carbon source. Among the relatively large number of isolates, only 3 were able to degrade N-ethylammelide, and in each case were shown to carry the atzB gene and atzC genes. The isolates, identified as Rhizobium leguminosarum, Flavobacterium sp., and Arthrobacter sp., were all readily substituted into an atrazine-degrading consortium to carry out N-ethylammelide degradation. The distribution of these genes among many different species in the soil microbial population suggests that these genes are highly mobile and over time may lead to generation of various atrazine-degrading consortia.

  13. Pressurized-water reactor internals aging degradation study. Phase 1

    Energy Technology Data Exchange (ETDEWEB)

    Luk, K.H. [Oak Ridge National Lab., TN (United States)

    1993-09-01

    This report documents the results of a Phase I study on the effects of aging degradations on pr internals. Primary stressers for internals an generated by the primary coolant flow in the they include unsteady hydrodynamic forces and pump-generated pressure pulsations. Other stressors are applied loads, manufacturing processes, impurities in the coolant and exposures to fast neutron fluxes. A survey of reported aging-related failure information indicates that fatigue, stress corrosion cracking (SCC) and mechanical wear are the three major aging-related degradation mechanisms for PWR internals. Significant reported failures include thermal shield flow-induced vibration problems, SCC in guide tube support pins and core support structure bolts, fatigue-induced core baffle water-jet impingement problems and excess wear in flux thimbles. Many of the reported problems have been resolved by accepted engineering practices. Uncertainties remain in the assessment of long-term neutron irradiation effects and environmental factors in high-cycle fatigue failures. Reactor internals are examined by visual inspections and the technique is access limited. Improved inspection methods, especially one with an early failure detection capability, can enhance the safety and efficiency of reactor operations.

  14. 以玉米秸秆为底物的纤维素降解菌与产电菌联合产电的可行性%Electricity generation from corn stover by cellulose degradation bacteria and exoelectrogenic bacteria

    Institute of Scientific and Technical Information of China (English)

    冯玉杰; 王鑫; 王赫名; 于艳玲; 李冬梅

    2009-01-01

    The possibility of direct electricity production from steam exploded com stover residue was studied in single chamber air-cathode microbial fuel cells ( MFCs) using two cellulose degrading bacteria ( Chaetomium sp. , Bacillus sp. ) and two cellulose degrading communities (PCS-S and H-C; stored in our laboratory) as biocatalysts. Both pure strains and mixed communities can decompose corn stover in MFCs, but little electricity ( < 90 mV , 1000Ω) was generated during this process. Increasing the temperature from 30 to 38. 5℃ did not increase voltage outputs. Using domestic wastewater solely as inoculum, electricity cannot be generated from degradation of com stover. Maximum voltage was observed in the MFC using H-C co-operated with the exoelectrogenic bacteria. The maximum power density from steam exploded com stover residue was 406 mW · m~(-2) , which was only 20% lower than the 510 mW·m~(-2) obtained using glucose as a substrate.%利用单室空气阴极微生物燃料电池(MFC)反应器,以玉米秸秆为底物.以本实验室筛选和保存的纤维素降解菌Chaetomium sp.和Bacillus sp.,以及纤维素降解混合菌PCS-S和H-C为秸秆降解的生物催化剂,探讨了以汽爆秸秆固体为底物进行微生物产电的可行性.结果表明,在MFC系统内,纤维索降解纯菌和混合菌均能使纤维素降解,但产生的电压很低(<90mV,1000Ω),升高温度(30-38.5℃)对电压输出无明显影响.单独以生活污水作为菌源不能直接降解秸秆产电.只有将H-C和生活污水(产电菌源)混合作为接种体,MFC才能获得较高的电压输出.此时得到的以汽爆秸秆固体作为底物时的最大功率密度为406mW·m-2,仅比葡萄糖作为底物时所得到的最大功率密度510 mW·m-2低20%.

  15. An improved automatic computer aided tube detection and labeling system on chest radiographs

    Science.gov (United States)

    Ramakrishna, Bharath; Brown, Matthew; Goldin, Jonathan; Cagnon, Christopher; Enzmann, Dieter

    2012-03-01

    Tubes like Endotracheal (ET) tube used to maintain patient's airway and the Nasogastric (NG) tube used to feed the patient and drain contents of the stomach are very commonly used in Intensive Care Units (ICU). The placement of these tubes is critical for their proper functioning and improper tube placement can even be fatal. Bedside chest radiographs are considered the quickest and safest method to check the placement of these tubes. Tertiary ICU's typically generate over 250 chest radiographs per day to confirm tube placement. This paper develops a new fully automatic prototype computer-aided detection (CAD) system for tube detection on bedside chest radiographs. The core of the CAD system is the randomized algorithm which selects tubes based on their average repeatability from seed points. The CAD algorithm is designed as a 5 stage process: Preprocessing (removing borders, histogram equalization, anisotropic filtering), Anatomy Segmentation (to identify neck, esophagus, abdomen ROI's), Seed Generation, Region Growing and Tube Selection. The preliminary evaluation was carried out on 64 cases. The prototype CAD system was able to detect ET tubes with a True Positive Rate of 0.93 and False Positive Rate of 0.02/image and NG tubes with a True Positive Rate of 0.84 and False Positive Rate of 0.02/image respectively. The results from the prototype system show that it is feasible to automatically detect both tubes on chest radiographs, with the potential to significantly speed the delivery of imaging services while maintaining high accuracy.

  16. Lab assessment of Bruce Unit 4 steam generator top-of-tubesheet cracking

    Energy Technology Data Exchange (ETDEWEB)

    Jevec, J.; Sarver, J. [Babcock and Wilcox Research Center (United States); King, P.; Yu, J. [Babcock and Wilcox Canada Ltd., Cambridge, Ontario (Canada); Sedman, K.; Durance, D. [Bruce Power, Tiverton, Ontario (Canada)

    2009-07-01

    An increasing number of significant circumferential indications were detected at the roll transition zone (RTZ) of Bruce Power Unit 4 steam generator (SG) tubing (sensitized Alloy 600) during the 2006 and 2007 Spring outages. Metallurgical examination of removed tubes found significant IGA/SCC associated with these indications. However, no circumferential indications were detected on Unit 4 SG tubing during the subsequent Fall 2007 and Spring 2008 outages. Based on a review of outage layup conditions it was theorized that the observed degradation occurs during an outage when the steam generator is drained for maintenance in combination with the presence of detrimental contaminants such as sulfur and copper. This theory was tested in the laboratory using a series of electrochemical and simulated crevice exposure tests. The oxygen/hydrazine reaction at room temperature and the resultant effect on the electrochemical potential of the sensitized Alloy 600 tubing were also studied in this program. Results from this test program are presented in this paper. The results indicate that exposure of the solutions to air tends to keep the sample in the sludge at a more reducing condition as compared to the free span tubing above the sludge resulting in a larger driving force for corrosion of the sample in the sludge. The theory that the defects in the RTZ were caused during drain-down outage conditions was shown to be plausible. (author)

  17. 自然循环蒸汽发生器倒U型管内倒流现象影响因素研究%Investigation on Factors Affecting Reverse Flow in Inverted U-Tubes of Steam Generator Under Natural Circulation

    Institute of Scientific and Technical Information of China (English)

    郝建立; 陈文振; 王少明

    2013-01-01

    For natural circulation, it is shown that reverse flow occurs in the inverted U-tubes of steam generator (SG) at certain low power levels. A flow model based on one-dimensional Oberbeck-Boussinesq equation was formulated to analyze this phenomenon. Two SGs of different scales were calculated. The results show that the reverse flow phenomenon occurs easily in the shorter U-tubes in small SG, but the phenomenon occurs easily in the longer U-tubes in large SG. The inlet temperature has great influence on the occurrence of reverse flow.%在某些自然循环工况下,蒸汽发生器部分倒U型管内存在倒流现象.基于一维OberbeckBoussinesq方程,建立了蒸汽发生器并联倒U型管内单相水流动传热模型,并以两种尺寸的蒸汽发生器为例进行了计算.计算结果表明,小型蒸汽发生器内短管易发生倒流,大型蒸汽发生器内长管易发生倒流;蒸汽发生器进口水温对倒流现象的发生具有重要的影响.

  18. Polysaccharide Degradation

    Science.gov (United States)

    Stone, Bruce A.; Svensson, Birte; Collins, Michelle E.; Rastall, Robert A.

    An overview of current and potential enzymes used to degrade polysaccharides is presented. Such depolymerases are comprised of glycoside hydrolases, glycosyl transferases, phosphorylases and lyases, and their classification, active sites and action patterns are discussed. Additionally, the mechanisms that these enzymes use to cleave glycosidic linkages is reviewed as are inhibitors of depolymerase activity; reagents which react with amino acid residues, glycoside derivatives, transition state inhibitors and proteinaceous inhibitors. The characterization of various enzymes of microbial, animal or plant origin has led to their widespread use in the production of important oligosaccharides which can be incorporated into food stuffs. Sources of polysaccharides of particular interest in this chapter are those from plants and include inulin, dextran, xylan and pectin, as their hydrolysis products are purported to be functional foods in the context of gastrointestinal health. An alternative use of degraded polysaccharides is in the treatment of disease. The possibility exists to treat bacterial exopolysaccharide with lyases from bacteriophage to produce oligosaccharides exhibiting bioactive sequences. Although this area is currently in its infancy the knowledge is available to investigate further.

  19. Enteral Tube Feeding and Pneumonia

    Science.gov (United States)

    Gray, David Sheridan; Kimmel, David

    2006-01-01

    To determine the effects of enteral