Eddy current inspection on heat exchanger tubes - problems and limitations

International Nuclear Information System (INIS)

Ilham Mukriz; Zainal Abidin Mohamed; Hairul Hasmoni Khairul Anuar; Mohd Salleh; Mahmood Dollah

2005-01-01

This paper focus on problems associated to eddy current inspection of heat exchanger tubes. A brief review on heat exchanger design and operation is presented. Eddy current technique in identifying inhomogeneity in tested tubes is discussed, highlighting its limitation in distinguishing between real pit type defects and other mundane anomalies. The limitation of the eddy current probe and equipment pertinent to the inspection are identified and areas of improvement are discussed. (Author)

Optimization of a Two Stage Pulse Tube Refrigerator for the Integrated Current Lead System

Science.gov (United States)

Maekawa, R.; Matsubara, Y.; Okada, A.; Takami, S.; Konno, M.; Tomioka, A.; Imayoshi, T.; Hayashi, H.; Mito, T.

2008-03-01

Implementation of a conventional current lead with a pulse tube refrigerator has been validated to be working as an Integrated Current Lead (ICL) system for the Superconducting Magnetic Energy Storage (SMES). Realization of the system is primarily accounted for the flexibility of a pulse tube refrigerator, which does not posses any mechanical piston and/or displacer. As for an ultimate version of the ICL system, a High Temperature Superconducting (HTS) lead links a superconducting coil with a conventional copper lead. To ensure the minimization of heat loads to the superconducting coil, a pulse tube refrigerator has been upgraded to have a second cooling stage. This arrangement reduces not only the heat loads to the superconducting coil but also the operating cost for a SMES system. A prototype two-stage pulse tube refrigerator, series connected arrangement, was designed and fabricated to satisfy the requirements for the ICL system. Operation of the first stage refrigerator is a four-valve mode, while the second stage utilizes a double inlet configuration to ensure its confined geometry. The paper discusses the optimization of second stage cooling to validate the conceptual design

Monte Carlo simulations to assess the effects of tube current modulation on breast dose for multidetector CT

International Nuclear Information System (INIS)

Angel, Erin; Yaghmai, Nazanin; Jude, Cecilia Matilda; DeMarco, John J; Cagnon, Christopher H; Goldin, Jonathan G; McNitt-Gray, Michael F; Primak, Andrew N; McCollough, Cynthia H; Stevens, Donna M; Cody, Dianna D

2009-01-01

Tube current modulation was designed to reduce radiation dose in CT imaging while maintaining overall image quality. This study aims to develop a method for evaluating the effects of tube current modulation (TCM) on organ dose in CT exams of actual patient anatomy. This method was validated by simulating a TCM and a fixed tube current chest CT exam on 30 voxelized patient models and estimating the radiation dose to each patient's glandular breast tissue. This new method for estimating organ dose was compared with other conventional estimates of dose reduction. Thirty detailed voxelized models of patient anatomy were created based on image data from female patients who had previously undergone clinically indicated CT scans including the chest area. As an indicator of patient size, the perimeter of the patient was measured on the image containing at least one nipple using a semi-automated technique. The breasts were contoured on each image set by a radiologist and glandular tissue was semi-automatically segmented from this region. Previously validated Monte Carlo models of two multidetector CT scanners were used, taking into account details about the source spectra, filtration, collimation and geometry of the scanner. TCM data were obtained from each patient's clinical scan and factored into the model to simulate the effects of TCM. For each patient model, two exams were simulated: a fixed tube current chest CT and a tube current modulated chest CT. X-ray photons were transported through the anatomy of the voxelized patient models, and radiation dose was tallied in the glandular breast tissue. The resulting doses from the tube current modulated simulations were compared to the results obtained from simulations performed using a fixed mA value. The average radiation dose to the glandular breast tissue from a fixed tube current scan across all patient models was 19 mGy. The average reduction in breast dose using the tube current modulated scan was 17%. Results were

Eddy current detection of corrosion damage in heat exchanger tubes

International Nuclear Information System (INIS)

Van Drunen, G.; Cecco, V.S.; Carter, J.R.

1980-05-01

Eddy current is often the most effective nondestructive test method available for in-service inspection of small bore tubing in heat exchangers. The basic principles, advantages and shortcomings of the technique are outlined. Typical eddy current indications from corrosion-related defects such as stress corrosion cracks, pitting and tube denting under support plates are presented. Eddy current signals from features such as magnetite deposits and ferromagnetic inclusions which might be mistaken for defects are also discussed. (auth)

Noise-based tube current reduction method with iterative reconstruction for reduction of radiation exposure in coronary CT angiography

International Nuclear Information System (INIS)

Shen, Junlin; Du, Xiangying; Guo, Daode; Cao, Lizhen; Gao, Yan; Bai, Mei; Li, Pengyu; Liu, Jiabin; Li, Kuncheng

2013-01-01

Purpose: To investigate the potential of noise-based tube current reduction method with iterative reconstruction to reduce radiation exposure while achieving consistent image quality in coronary CT angiography (CCTA). Materials and methods: 294 patients underwent CCTA on a 64-detector row CT equipped with iterative reconstruction. 102 patients with fixed tube current were assigned to Group 1, which was used to establish noise-based tube current modulation formulas, where tube current was modulated by the noise of test bolus image. 192 patients with noise-based tube current were randomly assigned to Group 2 and Group 3. Filtered back projection was applied for Group 2 and iterative reconstruction for Group 3. Qualitative image quality was assessed with a 5 point score. Image noise, signal intensity, volume CT dose index, and dose-length product were measured. Results: The noise-based tube current modulation formulas were established through regression analysis using image noise measurements in Group 1. Image noise was precisely maintained at the target value of 35.00 HU with small interquartile ranges for Group 2 (34.17–35.08 HU) and Group 3 (34.34–35.03 HU), while it was from 28.41 to 36.49 HU for Group 1. All images in the three groups were acceptable for diagnosis. A relative 14% and 41% reduction in effective dose for Group 2 and Group 3 were observed compared with Group 1. Conclusion: Adequate image quality could be maintained at a desired and consistent noise level with overall 14% dose reduction using noise-based tube current reduction method. The use of iterative reconstruction further achieved approximately 40% reduction in effective dose

Eddy current inspection of tubing

International Nuclear Information System (INIS)

Bauza, J. L. R.; Herrero, J.; Diaz, J.

1966-01-01

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

Effect of tube current modulation for dose estimation using a simulation tool on body CT examination

International Nuclear Information System (INIS)

Kawaguchi, Ai; Matsunaga, Yuta; Kobayashi, Masanao; Suzuki, Shoichi; Matsubara, Kosuke; Chida, Koichi

2015-01-01

The purpose of this study was to evaluate the effect of tube current modulation for dose estimation of a body computed tomography (CT) examination using a simulation tool. The authors also compared longitudinal variations in tube current values between iterative reconstruction (IR) and filtered back-projection (FBP) reconstruction algorithms. One hundred patients underwent body CT examinations. The tube current values around 10 organ regions were recorded longitudinally from tube current information. The organ and effective doses were simulated by average tube current values and longitudinal modulated tube current values. The organ doses for the bladder and breast estimated by longitudinal modulated tube current values were 20 % higher and 25 % lower than those estimated using the average tube current values, respectively. The differences in effective doses were small (mean, 0.7 mSv). The longitudinal variations in tube current values were almost the same for the IR and FBP algorithms. (authors)

Validating eddy current array probes for inspecting steam generator tubes

International Nuclear Information System (INIS)

Sullivan, S.P.; Cecco, V.S.; Obrutsky, L.S.

1997-01-01

A CANDU nuclear reactor was shut down for over one year because steam generator (SG) tubes had failed with outer diameter stress-corrosion cracking (ODSCC) in the U-bend section. Novel, single-pass eddy current transmit-receive probes, denoted as C3, were successful in detecting all significant cracks so that the cracked tubes could be plugged and the unit restarted. Significant numbers of tubes with SCC were removed from a SG in order to validate the results of the new probe. Results from metallurgical examinations were used to obtain probability-of-detection (POD) and sizing accuracy plots to quantify the performance of this new inspection technique. Though effective, the above approach of relying on tubes removed from a reactor is expensive, in terms of both economic and radiation-exposure costs. This led to a search for more affordable methods to validate inspection techniques and procedures. Methods are presented for calculating POD curves based on signal-to-noise studies using field data. Results of eddy current scans of tubes with laboratory-induced ODSCC are presented with associated POD curves. These studies appear promising in predicting realistic POD curves for new inspection technologies. They are being used to qualify an improved eddy current array probe in preparation for field use. (author)

Enhancing tube hydroformability by reducing the local strain gradient at potential necking sites

International Nuclear Information System (INIS)

Shin, S. G. R.; Joo, B. D.; Moon, Y. H.; Tyne, C. J. Van

2014-01-01

Bursting in tube hydroforming is preceded by localized deformation, which is often called necking. The retardation of the initiation of necking is a means to enhance hydroformability. Since high strain gradients occur at necking sites, a decrease in local strain gradients is an effective way to retard the initiation of necking. In the current study, the expansion at potential necking sites was intentionally restricted in order to reduce the strain gradient at potential necking sites. From the strain distribution obtained from FEM, it is possible to determine strain concentrated zones, which are the potential necking sites. Prior to the hydroforming of a trailing arm, lead patch is attached to the tube where the strain concentration would occur. Due to the incompressibility of lead, the tube expansion is locally restricted, and the resultant strain extends to adjacent regions of the tube during hydroforming. After the first stage of hydroforming, the lead is removed from the tube, and the hydroforming continues to obtain the targeted shape without the local restriction. This method was successfully used to fabricate a complex shaped automotive trailing arm that had previously failed during traditional hydroforming processing.

Eddy current test of fin tubes for a heat exchanger

International Nuclear Information System (INIS)

KIm, Young Joo; Lee, Se Kyung; Chung, Min Hwa

1992-01-01

Eddy current probes were designed for the test of fin tubes. Fin tubes, often used for heat exchangers, have uneven outer and inner surfaces to enhance the heat emission. The surface roughness make it difficult to detect flaws employing eddy current test(ECT). In order to overcome the difficulties we performed two types of works, one is the delopment of ECT probes, and the other is the signal processing including fast Fourier transform and digital filtering. In the development of ECT probes, we adopted empirical design method. Our ECT probes for fin tubes are inside diameter type. And we are specially concerned about geometric features such as the widths of the coils composing an ECT probe. We fabricated four probes with various coil widths. Eddy current test was performed using those ECT probes on specimens with artificial flaws. After analyzing the output signals, we found that, in order for the effective testing, the width of a coil should be determined considering the pitch of the fins of a tube. And we also learned that the frequency filtering could improve the s/n ratio.

Multifrequency eddy current testing of helical tubes of steam generators

International Nuclear Information System (INIS)

Pigeon, M.; David, B.

1983-06-01

In the event of a water-sodium reaction in a steam-generator of a fast breeder reactor, it is necessary to test the tubes close to the leak to evaluate the damage. In SUPERPHENIX, the tubes are about 100m long and are coiled on a dead body. This report describes the equipment and the technic to test such tubes with multifrequency eddy current technics [fr

Tube-AVB gap measurements using an eddy current rotating probe

International Nuclear Information System (INIS)

Badson, F.; Chiron, D.; Trumpff, B.

1988-01-01

The wears of tubes due to flow induced vibrations have been observed after a few years of operating PWR steam generators (SG). The vibration and wear are intimately related to the gap between tubes and anti-vibration bars (AVB's) located in the bundle. The authors report the development of an eddy current (EC) method for the measurement of this gap. The method is based on using an EC probe rotating in the tube. Since for each measurement zone the tube is interacting with two AVB's the use of a rotating EC probe is necessary to perform separate and accurate measurements of each tube-AVB gap

Eddy current inspection of weld defects in tubing

Science.gov (United States)

Katragadda, G.; Lord, W.

1992-01-01

An approach using differential probes for the inspection of weld defects in tubing is studied. Finite element analysis is used to model the weld regions and defects. Impedance plane signals are predicted for different weld defect types and compared wherever possible with signals from actual welds in tubing. Results show that detection and sizing of defects in tubing is possible using differential eddy current techniques. The phase angle of the impedance plane trajectory gives a good indication of the sizing of the crack. Data on the type of defect can be obtained from the shape of the impedance plane trajectory and the phase. Depending on the skin depth, detection of outer wall, inner wall, and subsurface defects is possible.

Reduced order model of draft tube flow

International Nuclear Information System (INIS)

Rudolf, P; Štefan, D

2014-01-01

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

Multifrequency Eddy current testing of heat exchange tubes with a rotating probe

International Nuclear Information System (INIS)

Levy, R.

1982-01-01

Multi-frequency eddy current analyses have been used in France industrially since 1975. In light of the experienced gained during many steam generator inspections, this technique was applied to the examination of sheet and tube heat exchangers featuring tubes in very different materials such as copper, stainless steel and titanium. The principle of multi-frequency Eddy current inspection is first reviewed, using the example of a condenser with nickel alloy tubes (Inconel, Incoloy). This is followed by the description of a specific application of this technique to a condenser with titanium tubes, analyzed with a rotating local probe [fr

Eddy current inspection of steam generator tubing plugs

International Nuclear Information System (INIS)

Cullen, W.K.

1990-01-01

In response to the issues raised regarding the integrity of nuclear steam generator tubing plugs manufactured from certain heats of Inconel 600, Westinghouse engineers have developed, qualified and implemented an eddy current inspection system for the in-place assessment of these plugs. The heart of the system is a robotic and effector which delivers an eddy current sensor through the reduced diameter of the plug expander and actuates the coil to physical contact with the expanded inside bore of the plug. Once deployed, the eddy current sensor is rotated along a helical path to produce a detailed scan of the plug surface above the final position of the expander. This testing produces an isometric display of degradation due to primary water stress corrosion cracking, on the inside surface of the plug. To date, successful inspections have been conducted at two nuclear units with two different robotic delivery systems. While designed specifically for mechanical plugs with a bottle bore cavity, the inspection system can also be used for expanded straight bore plugs. Details of the inspection system along with a discussion of qualification activities and actual field results are presented in this paper

Dose conversion coefficients for paediatric CT examinations with automatic tube current modulation

International Nuclear Information System (INIS)

Schlattl, H; Zankl, M; Becker, J; Hoeschen, C

2012-01-01

A common dose-saving technique used in modern CT devices is automatic tube current modulation (TCM), which was originally designed to also reduce the dose in paediatric CT patients. In order to be able to deduce detailed organ doses of paediatric models, dose conversion coefficients normalized to CTDI vol for an eight-week-old baby and seven- and eight-year-old children have been computed accounting for TCM. The relative difference in organ dose conversion coefficients with and without TCM is for many organs and examinations less than 10%, but can in some cases amount up to 30%, e.g., for the thyroid in the chest CT of the seven-year-old child. Overall, the impact of TCM on the conversion coefficients increases with increasing age. Besides TCM, also the effect of collimation and tube voltage on organ dose conversion coefficients has been investigated. It could be shown that the normalization to CTDI vol leads to conversion coefficients that can in most cases be considered to be independent of collimation and tube voltage. (paper)

Evaluation of the eddy-current method of inspecting steam generator tubing

International Nuclear Information System (INIS)

Flora, J.H.; Brown, S.D.; Weeks, J.R.

1976-01-01

The objective of this project has been to evaluate the eddy-current method of inspecting steam generator tubing by conducting a series of laboratory experiments with conventional eddy-current equipment. The experiments have involved obtaining eddy-current measurements on samples of 7/8-inch OD Inconel-600 tubing provided by the Westinghouse Nuclear Energy Systems Division. A variety of machined defects and some chemically induced flaws, such as stress corrosion cracks were fabricated in the tubing. Statistical evaluation of the data was employed to estimate the error encountered in measuring corrosion defects of various depths. It appears that the eddy-current technique can provide a reasonable measure of defect depth under certain conditions. On the other hand, the evaluation indicates that it is difficult to determine the depth of certain types of flaws with reliability and precision. Furthermore, although some defects as shallow as 10 percent of the tube wall could be detected, it was not possible to detect other types of flaws that were less than 40 percent deep even when the tube supports were not near the defects. The difficulty in detecting small volume flaws is attributed to low signal-to-noise ratio. Noise is a result of unwanted signals from test variables, such as wobble and variations in tube properties. The error in measurement of certain types of larger defects is associatedin part with test variables and also with the effects that the geometry of the defect has on the eddy-current signal patterns. The distortions in signal patterns caused by gradual wastage type defects and the poor reproducibility of signal patterns obtained from notches that represent stress corrosion cracks are described. Some developments that will rectify these detection and depth measurement problems are discussed

In-service examination of IHX tubing with eddy current NDT equipment

International Nuclear Information System (INIS)

Brown, R.L.

1972-01-01

Single and multiple frequency eddy current (ET) nondestructive testing (NDT) techniques and equipment were investigated for in-service inspection of sodium-contaminated intermediate heat exchanger (IHX) tubing. A four frequency technique, demonstrated in the laboratory, was relatively insensitive to signals caused by probe motion, tube support plates, and residual sodium on the outer surface of the tubes. No method was found to avoid the signals from residual sodium on the inside surfaces of the tube. (U.S.)

Eddy current proximity measurement of perpendicular tubes from within pressure tubes in CANDU nuclear reactors

Science.gov (United States)

Bennett, P. F. D.; Underhill, P. R.; Morelli, J.; Krause, T. W.

2018-04-01

Fuel channels in CANDU® (CANada Deuterium Uranium) nuclear reactors consist of two non-concentric tubes; an inner pressure tube (PT) and a larger diameter calandria tube (CT). Up to 400 horizontally mounted fuel channels are contained within a calandria vessel, which also holds the heavy water moderator. Certain fuel channels pass perpendicularly over horizontally oriented tubes (nozzles) that are part of the reactor's liquid injection shutdown system (LISS). Due to sag, these fuel channels are at risk of coming into contact with the LISS nozzles. In the event of contact between the LISS nozzle and CT, flow-induced vibrations from within the moderator could lead to fretting and deformation of the CT. LISS nozzle proximity to CTs is currently measured optically from within the calandria vessel, but from outside the fuel channels. Measurement by an independent means would provide confidence in optical results and supplement cases where optical observations are not possible. Separation of PT and CT, known as gap, is monitored from within the PT using a transmit-receive eddy current probe. Investigation of the eddy current based gap probe as a tool to also measure proximity of LISS nozzles was carried out experimentally in this work. Eddy current response as a function of LISS-PT proximity was recorded. When PT-CT gap, PT wall thickness, PT resistivity and probe lift-off variations were not present this dependence could be used to determine the LISS-PT proximity. This method has the potential to provide LISS-CT proximity using existing gap measurement data. Obtaining LISS nozzle proximity at multiple inspection intervals could be used to provide an estimate of the time to LISS-CT contact, and thereby provide a means of optimizing maintenance schedules.

Achieving consistent image quality and overall radiation dose reduction for coronary CT angiography with body mass index-dependent tube voltage and tube current selection

International Nuclear Information System (INIS)

Wang, G.; Gao, J.; Zhao, S.; Sun, X.; Chen, X.; Cui, X.

2014-01-01

Aim: To develop a quantitative body mass index (BMI)-dependent tube voltage and tube current selection method for obtaining consistent image quality and overall dose reduction in computed tomography coronary angiography (CTCA). Methods and materials: The images of 190 consecutive patients (group A) who underwent CTCA with fixed protocols (100 kV/193 mAs for 100 patients with a BMI of <27 and 120 kV/175 mAs for 90 patients with a BMI of >27) were retrospectively analysed and reconstructed with an adaptive statistical iterative reconstruction (ASIR) algorithm at 50% blending. Image noise was measured and the relationship to BMI was studied to establish BMI-dependent tube current for obtaining CTCA images with user-specified image noise. One hundred additional cardiac patients (group B) were examined using prospective triggering with the BMI-dependent tube voltage/current. CTCA image-quality score, image noise, and effective dose from groups B and C (subgroup of A of 100 patients examined with prospective triggering only) were obtained and compared. Results: There was a linear relationship between image noise and BMI in group A. Using a BMI-dependent tube current in group B, an average CTCA image noise of 27.7 HU (target 28 HU) and 31.7 HU (target 33 HU) was obtained for the subgroups of patients with BMIs of >27 and of <27, respectively, and was independent of patient BMI. There was no difference between image-quality scores between groups B and C (4.52 versus 4.60, p > 0.05). The average effective dose for group B (2.56 mSv) was 42% lower than group C (4.38 mSv; p < 0.01). Conclusion: BMI-dependent tube voltage/current selection in CTCA provides an individualized protocol that generates consistent image quality and helps to reduce overall patient radiation dose. - Highlights: • BMI-dependent kVp and mA selection method may be established in CCTA. • BMI-dependent kVp and mA enables consistent CCTA image quality. • Overall dose reduction of 40% can

Topogram-based tube current modulation of head computed tomography for optimizing image quality while protecting the eye lens with shielding.

Science.gov (United States)

Lin, Ming-Fang; Chen, Chia-Yuen; Lee, Yuan-Hao; Li, Chia-Wei; Gerweck, Leo E; Wang, Hao; Chan, Wing P

2018-01-01

Background Multiple rounds of head computed tomography (CT) scans increase the risk of radiation-induced lens opacification. Purpose To investigate the effects of CT eye shielding and topogram-based tube current modulation (TCM) on the radiation dose received by the lens and the image quality of nasal and periorbital imaging. Material and Methods An anthropomorphic phantom was CT-scanned using either automatic tube current modulation or a fixed tube current. The lens radiation dose was estimated using cropped Gafchromic films irradiated with or without a shield over the orbit. Image quality, assessed using regions of interest drawn on the bilateral extraorbital areas and the nasal bone with a water-based marker, was evaluated using both a signal-to-noise ratio (SNR) and contrast-noise ratio (CNR). Two CT specialists independently assessed image artifacts using a three-point Likert scale. Results The estimated radiation dose received by the lens was significantly lower when barium sulfate or bismuth-antimony shields were used in conjunction with a fixed tube current (22.0% and 35.6% reduction, respectively). Topogram-based TCM mitigated the beam hardening-associated artifacts of bismuth-antimony and barium sulfate shields. This increased the SNR by 21.6% in the extraorbital region and the CNR by 7.2% between the nasal bones and extraorbital regions. The combination of topogram-based TCM and barium sulfate or bismuth-antimony shields reduced lens doses by 12.2% and 27.2%, respectively. Conclusion Image artifacts induced by the bismuth-antimony shield at a fixed tube current for lenticular radioprotection were significantly reduced by topogram-based TCM, which increased the SNR of the anthropomorphic nasal bones and periorbital tissues.

Garter spring location of pressure tube for PHWR using eddy current testing methods

International Nuclear Information System (INIS)

Lee, Y. S.; Yang, D. J.; Jeong, H. K.

2001-01-01

There are garter springs between pressure tube and calandria tube for PHWR. If the space of these garter springs become to be changed, the sagging of tube is caused and the contact between the pressure tube and calandria tube will cause the tube to be failed. AECL has applied the eddy current testing methods using send-receive type probe for this purpose, but this study apply eddy current testing methods using bobbin differential type probe to detection of garter spring location. And we did the computer simulation using VIC-3D code and compared it with experiments results for inspection 1 ∼ 11kHz. The results was that the garter spring signal was successfully detected for every frequency, and 5 kHz was best

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.

Evaluation of the eddy-current method for the inspection of steam generator tubing: denting

International Nuclear Information System (INIS)

Brown, S.D.; Flora, J.H.

1977-01-01

Continued evaluation of existing eddy-current in-service inspection (ISI) methods for steam generator tubing has emphasized the effects of denting. Denting is a circumferential deformation of the tube in the support region as a result of the formation of a magnetite, Fe 3 O 4 , corrosion product on the carbon steel tube support plate in the crevice between the support plate and the tube wall. The effects of denting on eddy current inspection are twofold: (1) The detection and measurement of defects in the dented region is hampered by the distortion of the eddy-current response signals caused by the dents and (2) large dents may prevent the passage of high fill factor probes forcing the inspection teams to use a smaller probe in undented regions. Unless appropriate measures are taken, less reliable detection of defects and estimation of their depth can result. The report presents an experimental evaluation of existing eddy-current ISI methods when used to inspect dented regions. Tubes were mechanically dented to simulate various degrees of service induced denting. These tubes were then inserted in carbon steel tube support plates and the crevice region between the support plate and tube was subsequently packed with powdered magnetite. Diametral dent sizes considered during this program varied between 1 and 10 mils. Eddy-current signal patterns and strip chart recordings were obtained using a variety of test parameters, such as frequency, phase rotation and coil configuration, on tube samples containing various degrees of denting and with several types of defects in the dented system

Current-driven vortex domain wall motion in wire-tube nanostructures

Energy Technology Data Exchange (ETDEWEB)

Espejo, A. P. [Departamento de Física, Universidad de Santiago de Chile (USACH), Av. Ecuador 3493, 9170124 Santiago (Chile); Institute of Nanostructure and Solid State Physics, University of Hamburg, Jungiusstrasse 11, D-20355 Hamburg (Germany); Vidal-Silva, N. [Departamento de Física, Universidad de Santiago de Chile (USACH), Av. Ecuador 3493, 9170124 Santiago (Chile); López-López, J. A. [Departamento de Física, Universidad Técnica Federico Santa María, Av. España 1680, Valparaíso (Chile); Goerlitz, D.; Nielsch, K. [Institute of Nanostructure and Solid State Physics, University of Hamburg, Jungiusstrasse 11, D-20355 Hamburg (Germany); Escrig, J. [Departamento de Física, Universidad de Santiago de Chile (USACH), Av. Ecuador 3493, 9170124 Santiago (Chile); Center for the Development of Nanoscience and Nanotechnology (CEDENNA), Av. Ecuador 3493, 9170124 Santiago (Chile)

2015-03-30

We have investigated the current-driven domain wall motion in nanostructures comprised of a pair of nanotube and nanowire segments. Under certain values of external magnetic fields, it is possible to pin a vortex domain wall in the transition zone between the wire and tube segments. We explored the behavior of this domain wall under the action of an electron flow applied in the opposite direction to the magnetic field. Thus, for a fixed magnetic field, it is possible to release a domain wall pinned simply by increasing the intensity of the current density, or conversely, for a fixed current density, it is possible to release the domain wall simply decreasing the magnetic external field. When the domain wall remains pinned due to the competition between the current density and the magnetic external field, it exhibits a oscillation frequency close to 8 GHz. The amplitude of the oscillations increases with the current density and decreases over time. On the other hand, when the domain wall is released and propagated through the tube segment, this shows the standard separation between a steady and a precessional regime. The ability to pin and release a domain wall by varying the geometric parameters, the current density, or the magnetic field transforms these wire-tube nanostructures in an interesting alternative as an on/off switch nano-transistor.

TU-EF-204-07: Add Tube Current Modulation to a Low Dose Simulation Tool for CT Systems

International Nuclear Information System (INIS)

Ding, Y.; Wen, G.; Brown, K.; Klahr, P.; Dhanantwari, A.

2015-01-01

Purpose: We extended the capabilities of a low dose simulation tool to model Tube-Current Modulation (TCM). TCM is widely used in clinical practice to reduce radiation dose in CT scans. We expect the tool to be valuable for various clinical applications (e.g., optimize protocols, compare reconstruction techniques and evaluate TCM methods). Methods: The tube current is input as a function of z location, instead of a fixed value. Starting from the line integrals of a scan, a new Poisson noise realization at a lower dose is generated for each view. To validate the new functionality, we compared simulated scans with real scans in image space. Results: First we assessed noise in the difference between the low-dose simulations and the original high-dose scan. When the simulated tube current is a step function of z location, the noise at each segment matches the noise of 3 separate constant-tube-current-simulations. Secondly, with a phantom that forces TCM, we compared a low-dose simulation with an equivalent real low-dose scan. The mean CT number of the simulated scan and the real low-dose scan were 137.7±0.6 and 137.8±0.5 respectively. Furthermore, with 240 ROIs, the noise of the simulated scan and the real low-dose scan were 24.03±0.45 and 23.99±0.43 respectively, and they were not statistically different (2-sample t-test, p-value=0.28). The facts that the noise reflected the trend of the TCM curve, and that the absolute noise measurements were not statistically different validated the TCM function. Conclusion: We successfully added tube-current modulation functionality in an existing low dose simulation tool. We demonstrated that the noise reflected an input tube-current modulation curve. In addition, we verified that the noise and mean CT number of our simulation agreed with a real low dose scan. The authors are all employees of Philips. Yijun Ding is also supported by NIBIB P41EB002035 and NIBIB R01EB000803

CT breast dose reduction with the use of breast positioning and organ-based tube current modulation.

Science.gov (United States)

Fu, Wanyi; Tian, Xiaoyu; Sturgeon, Gregory M; Agasthya, Greeshma; Segars, William Paul; Goodsitt, Mitchell M; Kazerooni, Ella A; Samei, Ehsan

2017-02-01

This study aimed to investigate the breast dose reduction potential of a breast-positioning (BP) technique for thoracic CT examinations with organ-based tube current modulation (OTCM). This study included 13 female anthropomorphic computational phantoms (XCAT, age range: 27-65 y.o., weight range: 52-105.8 kg). Each phantom was modified to simulate three breast sizes in standard supine geometry. The modeled breasts were then morphed to emulate BP that constrained the majority of the breast tissue inside the 120° anterior tube current (mA) reduction zone. The OTCM mA value was modeled using a ray-tracing program, which reduced the mA to 20% in the anterior region with a corresponding increase to the posterior region. The organ doses were estimated by a validated Monte Carlo program for a typical clinical CT system (SOMATOM Definition Flash, Siemens Healthcare). The simulated organ doses and organ doses normalized by CTDI vol were used to compare three CT protocols: attenuation-based tube current modulation (ATCM), OTCM, and OTCM with BP (OTCM BP ). On average, compared to ATCM, OTCM reduced breast dose by 19.3 ± 4.5%, whereas OTCM BP reduced breast dose by 38.6 ± 8.1% (an additional 23.8 ± 9.4%). The dose saving of OTCM BP was more significant for larger breasts (on average 33, 38, and 44% reduction for 0.5, 1, and 2 kg breasts, respectively). Compared to ATCM, OTCM BP also reduced thymus and heart dose by 15.1 ± 7.4% and 15.9 ± 6.2% respectively. In thoracic CT examinations, OTCM with a breast-positioning technique can markedly reduce unnecessary exposure to radiosensitive organs in anterior chest wall, specifically breast tissue. The breast dose reduction is more notable for women with larger breasts. © 2016 American Association of Physicists in Medicine.

Development of a 3D electromagnetic model for eddy current tubing inspection application to steam generator tubing

Energy Technology Data Exchange (ETDEWEB)

Maillot, V. [Institut de Radioprotection et de Surete Nucleaire, IRSN, 92 - Fontenay aux Roses (France); Pichenot, G.; Premel, D.; Sollier, T. [CEA Saclay, DRT/DECS, 91 - Gif-sur-Yvette (France)

2003-10-01

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. (authors)

Achieving reduced fouling of cooling water exchangers with stainless steel tubes

International Nuclear Information System (INIS)

Iftikhar, A.; Mir, N.

2010-01-01

Good performance of cooling water heat exchangers plays a vital role in the over all energy efficiency of a chemical plant. Heavy fouling on carbon steel tubes of the cooling water exchangers was causing poor performance and frequent cleaning requirement. The carbon steel tubes were replaced with stainless steel tubes. Improved performance was achieved and cleaning frequency reduced. The paper covers the details of study and methodology applied for the above changes along with summary of results. (author)

Optimum Frequency for Eddy Current Testing Method of SMART SG tubes

International Nuclear Information System (INIS)

Lee, Yoon Sang; Jung, Hyun Kyu; Choung, Yun Hang

2009-01-01

The SMART SG tubes will be made of Alloy 690. The outside diameter will be 17 mm and the thickness will be 2.5 mm. They will be assembled helically around, and their innermost diameter will be about 600 mm and the total length will be about 32 meters. For safety, SMART SG tubes are designed for use with thick tubes such as 2.5 mm thickness compared to about 1 mm thickness of normal Korean standard pressurized water reactor tubes. Due to using thick tubes such as 2.5 mm varieties, it was doubted that the Eddy Current Testing Method (ECT) would be a feasible method. Therefore we are trying to simulate the bobbin probe signal for SMART SG tubes and comparing it to PWR SG ECT probe signal using VIM software, checking for the applicability of ECT. Also we are trying to compare the ECT signal of 2.5 mm thick stainless tubes to check if they are possible substitute material

Method and apparatus for remote tube crevice detection by current and voltage probe resistance measurement

Science.gov (United States)

Kikta, Thomas J.; Mitchell, Ronald D.

1992-01-01

A method and apparatus for determining the extent of contact between an electrically conducting tube and an electrically conductive tubesheet surrounding the tube, based upon the electrical resistance of the tube and tubesheet. A constant current source is applied to the interior of the electrically conducting tube by probes and a voltmeter is connected between other probes to measure the voltage at the point of current injection, which is inversely proportional to the amount of contact between the tube and tubesheet. Namely, the higher the voltage measured by the voltmeter, the less contact between the tube and tubesheet.

Guiding effect of bent macroscopic quartz tube for high current electron beam

International Nuclear Information System (INIS)

Zhang Mingwu; Chen Jing; Wu Yehong; Yang Bian; Wang Wei; Xue Yingli; Yu Deyang; Cai Xiaohong

2012-01-01

By using an incident electron beam with the high current and high energy, the guiding effect of the bent macroscopic quartz tube for the electron beam has been investigated. The angular distributions of outgoing electrons depending on the current and energy of incident electrons were measured. The dependences of electron transmitted fraction on energy and current of incident electrons are also shown. As the incident electron energy increasing, the electron transmitted fraction increases, but it decreases while the incident electron current increasing. The results have been compared with the present data. This work presents, the process of guiding electrons is essentially different from that of guiding highly charged ions, the guiding electron beam was caused by both elastic and inelastic collisions between electrons and inner walls of quartz tube, rather than self-organized charging effect on the surface of inner wall of quartz tube. (authors)

Automation of inspection methods for eddy current testing of steam generator tubes

International Nuclear Information System (INIS)

Meurgey, P.; Baumaire, A.

1990-01-01

Inspection of all the tubes of a steam generator when the reactor is stopped is required for some of these exchangers affected by stress corrosion cracking. Characterization of each crack, in each tube is made possible by the development of software for processing the signals from an eddy current probe. The ESTELLE software allows a rapid increase of tested tubes, more than 80,000 in 1989 [fr

Reliability of eddy current examination of steam generator tubes

International Nuclear Information System (INIS)

Birks, A.S.; Ferris, R.H.; Doctor, P.G.; Clark, R.A.; Spanner, G.E.

1985-04-01

A unique study of nondestructive examination reliability is underway at the Pacific Northwest Laboratory under US Nuclear Regulatory Commission sponsorship. Project participants include the Electric Power Research Institute and consortiums from France, Italy, and Japan. This study group has conducted a series of NDE examinations of tubes from a retired-from-service steam generator, using commercially available multifrequency eddy current equipment and ASME procedures. The examination results have been analyzed to identify factors contributing to variations in NDE inspection findings. The reliability of these examinations will then be validated by destructive analyses of the steam generator tubes. The program is expected to contribute to development of a model for steam generator inservice inspection sampling plans and inspection periods, as well as to improved regulatory guidelines for tube plugging

Evaluation and field validation of Eddy-Current array probes for steam generator tube inspection

International Nuclear Information System (INIS)

Dodd, C.V.; Pate, J.R.

1996-07-01

The objective of the Improved Eddy-Current ISI for Steam Generator Tubing 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 describes the design of specialized high-speed 16-coil eddy-current array probes. Both pancake and reflection coils are considered. Test results from inspections using the probes in working steam generators are given. Computer programs developed for probe calculations are also supplied

Performance demonstration requirements for eddy current steam generator tube inspection

International Nuclear Information System (INIS)

Kurtz, R.J.; Heasler, P.G.; Anderson, C.M.

1992-10-01

This paper describes the methodology used for developing performance demonstration tests for steam generator tube eddy current (ET) inspection systems. The methodology is based on statistical design principles. Implementation of a performance demonstration test based on these design principles will help to ensure that field inspection systems have a high probability of detecting and correctly sizing tube degradation. The technical basis for the ET system performance thresholds is presented. Probability of detection and flaw sizing tests are described

The Cause of an Eddy Current Signal Noise from a Steam Generator Tube and its Effect on the Detectability of a Crack

International Nuclear Information System (INIS)

Lee, Deok Hyun; Choi, Myung Sik; Hur, Do Haeng; Kim, Kyung Mo; Han, Jung Ho

2008-01-01

An eddy current inspection has been applied for a pre-service and in-service examination of a steam generator in nuclear power plants. The experience from the inspection of steam generators showed that many plants had an excessive number of tubes with eddy current noise signals over several hundreds, which originated from manufacturing anomalies. The plants in U.S suffered significant downstream inspection costs, history reviews, and diagnostic testing because some signals resembled flaws and others masked a flaw. These lessens learned resulted in issuing the guidelines for steam generator tubing specifications and repair, in order to reduce the number of anomalous signals in the tubes and also to provide the requirement of a signal to noise ratio by applying a field type examination with bobbin coil eddy current probes at a manufacturing process. Besides the noise signals of a bobbin coil eddy current probe from manufacturing anomalies, the excessive background noise of the rotating coil eddy current probe signal is frequently observed from a tube and it negatively affects the detection and sizing estimate of a defect. Since the inspection intervals are being extended up to 60 months for the more recent steam generator of corrosion resistant alloy 690TT tubing, the detection of an earlier crack and an accurate sizing are becoming more important in the activity of a non-destructive examination. In this study, the cause of an eddy current signal noise of a rotating coil probe from a steam generator tube was examined and its influence on the detectability of a crack was analyzed

Duality of the magnetic flux tube and electric current descriptions magnetospheric plasma and energy flow

International Nuclear Information System (INIS)

Atkinson, G.

1981-01-01

The duality between electric current and magnetic flux tubes is outlined for the magnetosphere. Magnetic flux tubes are regarded as fluid elements subjected to various stresses. Current closure then becomes the dual of stress balance, and Poynting vector energy flow a dual of J x E dissipation. The stresses acting on a flux tube are magnetic stresses, which correspond to currents at a distance, and plasma stresses, which correspond to local currents. The duality between current and stress is traced for ionospheric ion drag forces, solar wind stresses at the magnetopause, inertial effects, and the effects of energetic plasma on flux tubes. The stress balance and dual current systems are outlined for idealized magnetospheres of increasing complexity. For a simple magnetosphere with no convective flow, the balance stresses are solar wind pressure and neutral sheet plasma pressure. The corresponding current systems are the Chapman-Ferraro magnetopause currents and the magetotail current system. The introduction of convective flow introduces further stresses: ionospheric ion drag. Alfven layer shielding, and an imbalance in day-night magnetic stresses due to transport of flux tubes to the nightside by the solar wind. These stresses balance, and hence the corresponding additional currents (the ionospheric Pedersen current and the electrojets, the partial ring current, and two other current systems from the magnetopause and tail) must form a closed current system and do so by the region I and II field-aligned currents of Iijima and Potemra. The energy flow in the above models is described in terms of both Poynting vectors and the above current systems. Temporal variations examined are (1) an increase in dayside merging and/or nightside reconnection, (2) an increase in the energy density of plasma in the plasma sheet, (3) an increase in ionospheric conductivity, and (4) an increase in solar wind pressure

Current state and development trends of inspections of steam generator tubes by eddy currents method

International Nuclear Information System (INIS)

Kubis, S.; Herman, M.

1988-01-01

The requirements are presented for steam generator tube testing and the factors are discussed affecting the accuracy of measurement by the eddy currents method. The individual types of the eddy currents method are described, such as the single-frequency method, the multi-frequency method and the pulse eddy currents method. The demands are summed up on manipulator systems whose design is adapted to the steam generator configuration conditions. (E.S.). 5 figs., 16 possu

Investigation of the influence of image reconstruction filter and scan parameters on operation of automatic tube current modulation systems for different CT scanners

International Nuclear Information System (INIS)

Sookpeng, Supawitoo; Martin, Colin J.; Gentle, David J.

2015-01-01

Variation in the user selected CT scanning parameters under automatic tube current modulation (ATCM) between hospitals has a substantial influence on the radiation doses and image quality for patients. The aim of this study was to investigate the effect of changing image reconstruction filter and scan parameter settings on tube current, dose and image quality for various CT scanners operating under ATCM. The scan parameters varied were pitch factor, rotation time, collimator configuration, kVp, image thickness and image filter convolution (FC) used for reconstruction. The Toshiba scanner varies the tube current to achieve a set target noise. Changes in the FC setting and image thickness for the first reconstruction were the major factors affecting patient dose. A two-step change in FC from smoother to sharper filters doubles the dose, but is counterbalanced by an improvement in spatial resolution. In contrast, Philips and Siemens scanners maintained tube current values similar to those for a reference image and patient, and the tube current only varied slightly for changes in individual CT scan parameters. The selection of a sharp filter increased the image noise, while use of iDose iterative reconstruction reduced the noise. Since the principles used by CT manufacturers for ATCM vary, it is important that parameters which affect patient dose and image quality for each scanner are made clear to operator to aid in optimisation. (authors)

High-current beam transport in electrostatic accelerator tubes

International Nuclear Information System (INIS)

Ramian, G.; Elais, L.

1987-01-01

The UCSB Free Electron Laser (FEL) has successfully demonstrated the use of a commercial 6 megavolt electrostatic accelerator as a high current beam source in a recirculating configuration. The accelerator, manufactured by National Electrostatics Corp. (NEC), Middleton WI, uses two standard high gradient accelerator tubes. Suppression of ion multiplication was accomplished by NEC with apertures and a shaped electrostatic field. This field shaping has fortuitously provided a periodically reversing radial field component with sufficient focusing strength to transport electron beams of up to 3 Amps current. Present two-stage FEL work requires a 20 Amp beam and proposed very high voltage FEL designs require currents as high as 100 Amps. A plan to permit transport of such high current beams by the addition of solenoidal focussing elements is described

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

International Nuclear Information System (INIS)

Wong, W.A.; Cairelli, J.E.; Swec, D.M.; Doeberling, T.J.; Lakatos, T.F.; Madi, F.J.

1994-01-01

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

Measurement by eddy currents of tube-antivibratory bar gap steam generators of PWR power plants

International Nuclear Information System (INIS)

Savin, E.; Bieth, M.; Floze, J.C.

1990-01-01

In steam generators tubes are maintained by AVB to limit vibrations amplitude induced by secondary fluid flow. After some years wear sometimes occurs. For gap measurement between tubes and AVB Framatome developed a method based on eddy current and using a probe rotating inside the tube [fr

Considerations on an automatic computed tomography tube current modulation system

International Nuclear Information System (INIS)

Moro, L.; Panizza, D.; D'Ambrosio, D.; Carne, I.

2013-01-01

The scope of this study was to evaluate the effects on radiation output and image noise varying the acquisition parameters with an automatic tube current modulation (ATCM) system in computed tomography (CT). Chest CT examinations of an anthropomorphic phantom were acquired using a GE LightSpeed VCT 64-slice tomograph. Acquisitions were performed using different pitch, slice thickness and noise index (NI) values and varying the orientation of the scanned projection radiograph (SPR). The radiation output was determined by the CT dose index (CTDI vol ). Image noise was evaluated measuring the standard deviation of CT numbers in several regions of interest. The radiation output was lower if the SPR was acquired in the anterior-posterior projection. The radiation dose with the posterior-anterior SPR was higher, because the divergence of the X-ray beam magnifies the anatomical structures closest to the tube, especially the spinal column, and this leads the ATCM system to estimate higher patient attenuation values and, therefore, to select higher tube current values. The NI was inversely proportional to the square root of the CTDI vol and, with fixed NI, the CTDI vol increased as the slice thickness decreased. This study suggests some important issues to use the GE ATCM system efficiently. (authors)

New tube fitting range can slash assembly time, reduce tube material costs and eliminate hot work

Energy Technology Data Exchange (ETDEWEB)

Anon.

2008-09-15

Parker Instrumentation has developed a permanent tube connection technology known as Phastite for use in high pressure applications such as in the offshore oil and gas sector. The Phastite push-fit connector offers major savings over traditional permanent and higher pressure connection techniques such as welded or cone-and-thread tube fittings. It also reduces assembly times by 20-fold or more and eliminates the need for hot work permits. The fittings are designed to withstand working pressures up to 1,379 bar. Phastite tube fittings can be used on offshore platforms, as well as on support vessels,, subsea equipment and ROVs such as hydraulic systems for wellhead control, emergency shut down, chemical injection, pumping packages, gas booster systems and test equipment. The connectors offer considerable savings in material cost and weight because they do not need to be used with more expensive tubing with extra thickness to accommodate a thread. Phastite is also resistant to vibration and does not need any anti-vibration accessories. A joint can be made in a matter of seconds with a simple handheld hydraulic tool that makes the push-fit connection. A sealing mechanism based on a series of defined internal ridges creates a secure seal by radial compression. The ridges grip in a way that retains all of the tubing's strength. An additional characteristic is the maintenance free nature of the Phastite connection. 1 fig.

Eddy current technology for heat exchanger and steam generator tube inspection

Energy Technology Data Exchange (ETDEWEB)

Obrutsky, L.; Lepine, B.; Lu, J.; Cassidy, R.; Carter, J. [Atomic Energy of Canada Limited, Chalk River, Ontario (Canada)

2004-07-01

A variety of degradation modes can affect the integrity of both heat exchanger (HX) and balance of plant tubing, resulting in expensive repairs, tube plugging or replacement of tube bundles. One key component for ensuring tube integrity is inspection and monitoring for detection and characterization of the degradation. In-service inspection of HX and balance of plant tubing is usually carried out using eddy current (EC) bobbin coils, which are adequate for the detection of volumetric degradations. However, detection and quantification of additional modes of degradation such as pitting, intergranular attack (IGA), axial cracking and circumferential cracking require specialized probes. The need for timely, reliable detection and characterization of these modes of degradation is especially critical in Nuclear Generating Stations. Transmit-receive single-pass array probes, developed by AECL, offer high defect detectability in conjunction with fast and reliable inspection capabilities. They have strong directional properties, permitting probe optimization for circumferential or axial crack detection. Compared to impedance probes, they offer improved performance in the presence of variable lift-off. This EC technology can help resolve critical detection issues at susceptible areas, such as the rolled-joint transitions at the tubesheet, U-bends and tube-support intersections. This paper provides an overview of the operating principles and the capabilities of advanced ET inspection technology available for HX tube inspection. Examples of recent application of this technology in Nuclear Generating Stations (NGSs) are discussed. (author)

Eddy current technology for heat exchanger and steam generator tube inspection

International Nuclear Information System (INIS)

Obrutsky, L.; Lepine, B.; Lu, J.; Cassidy, R.; Carter, J.

2004-01-01

A variety of degradation modes can affect the integrity of both heat exchanger (HX) and balance of plant tubing, resulting in expensive repairs, tube plugging or replacement of tube bundles. One key component for ensuring tube integrity is inspection and monitoring for detection and characterization of the degradation. In-service inspection of HX and balance of plant tubing is usually carried out using eddy current (EC) bobbin coils, which are adequate for the detection of volumetric degradations. However, detection and quantification of additional modes of degradation such as pitting, intergranular attack (IGA), axial cracking and circumferential cracking require specialized probes. The need for timely, reliable detection and characterization of these modes of degradation is especially critical in Nuclear Generating Stations. Transmit-receive single-pass array probes, developed by AECL, offer high defect detectability in conjunction with fast and reliable inspection capabilities. They have strong directional properties, permitting probe optimization for circumferential or axial crack detection. Compared to impedance probes, they offer improved performance in the presence of variable lift-off. This EC technology can help resolve critical detection issues at susceptible areas, such as the rolled-joint transitions at the tubesheet, U-bends and tube-support intersections. This paper provides an overview of the operating principles and the capabilities of advanced ET inspection technology available for HX tube inspection. Examples of recent application of this technology in Nuclear Generating Stations (NGSs) are discussed. (author)

Design options for reducing the impact of the fill-tube in ICF implosion experiments on the NIF

Science.gov (United States)

Weber, Christopher R.; Berzak Hopkins, L. F.; Casey, D. T.; Clark, D. S.; Hammel, B. A.; Le Pape, S.; Macphee, A.; Milovich, J.; Pickworth, L. A.; Robey, H. F.; Smalyuk, V. A.; Stadermann, M.; Felker, S. J.; Nikroo, A.; Thomas, C. A.; Crippen, J.; Rice, N.

2017-10-01

Inertial Confinement Fusion (ICF) capsules on the National Ignition Facility (NIF) are filled with thermonuclear fuel through a fill-tube. When the capsule implodes, perturbations caused by the fill-tube allow ablator material to mix into the hot spot and reduce fusion performance. This talk will explore several design options that attempt to reduce this damaging effect. Reducing the diameter of the fill-tube and its entrance hole is the obvious course and has been tested in experiments. Simulations also show sensitivity to the amount of glue holding the fill-tube to the capsule and suggest that careful control of this feature can limit the amount of injected mass. Finally, an off-axis fill-tube reduces the initial squirt of material into the fuel and may be a way of further optimizing this engineering feature. Work performed under the auspices of the U.S. D.O.E. by Lawrence Livermore National Laboratory under Contract No. DE-AC52-07NA27344.

Eddy current tube testing unit

International Nuclear Information System (INIS)

Dufayet, J.P.; Duret, G.

1975-01-01

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

Signal Characteristics of Eddy Current Test for Intergranular Attack of Steam Generator Tubes

International Nuclear Information System (INIS)

Choi, Myung Sik; Lee, Deok Hyun; Han, Jung Ho; Hur, Do Haeng; Cho, Se Gon; Yim, Chang Jae

2002-01-01

Because intergranular attack (IGA), one of the localized corrosion forms occurring on steam generator tubes, can not be fabricated by an electric discharge machining method, there are few data for the eddy current test (ECT) characteristics of IGA. In this paper, the characteristics of eddy current signals are evaluated using nonexpanded tubes with IGA defects formed in 0.1 M sodium tetrathionate solution at 40 .deg. C. The detectability and sizing accuracy of IGA were discussed in terms of the coil type and frequency of the ECT probes

The impact of the AEC mode of tube current on the dose at CT scans

Energy Technology Data Exchange (ETDEWEB)

Moon, Il Bong; Dong, Kyung Rae [Dept. of Radiological Technology, Gwangju Health University, Gwangju (Korea, Republic of); Kim, Kwang Cheol [Dept. of of Nuclear Engineering, Chosun University,Gwangju (Korea, Republic of)

2016-11-15

In this study, the automatic exposure control (AEC) modes of tube current (SIEMENSCare Dose 4D and GE AEC mode) that CT manufacturers are using was applied to neck, chest and abdomen in order to determine the difference in the respective dose parameters (CTDIvol, DLP and mSv) resulting from the dose reduction. Equipment in use at C university adopted Care Dose 4D of Siemens and AEC mode of General Electric (GE), and the x-ray exposure conditions were adjusted to be as identical as possible between the experiments. For the assessment of the dose reduction, the differences between the doses with and without the use of the tube current AEC mode by the respective manufacturer were measured for each body part including neck, chest and abdomen of a human phantom, Rando Phantom (Art-200x, Fluke Biomedical, USA). First, the assessment of SIEMENS-Care Dose 4D yielded the following results. At the neck, the automatic exposure control resulted in a 3.3% reduction in CTDIvol and DLP, and a 3% reduction in the effective dose, mSv, compared to manual exposure control. The automatic exposure control at the chest displayed the reduction in CTDIvol and DLP by 25.5%, and in the effective dose, mSv, by 25.4% compared to the manual exposure control. In case of abdomen, CTDIvol and DLP were shown to be reduced by 16%, and the effective dose (mSv) by 16.3% under the automatic exposure control compared to the manual exposure. Second, the assessment results of GE AEC mode are as follows. The automatic exposure control at the neck resulted in a 45.1% reduction in CTDIvol and DLP, and a 44.7% reduction in the effective dose (mSv) in comparison to the manual exposure control. At the chest, the automatic exposure control displayed a 47.6% reduction in CTDIvol and DLP, and a 47.5% reduction in the effective dose, mSv, compared to the manual exposure control. At the abdomen, it was shown that CTDIvol and DLP were reduced by 26.9%, and the effective dose (mSv) by 26.8% under the automatic

The impact of the AEC mode of tube current on the dose at CT scans

International Nuclear Information System (INIS)

Moon, Il Bong; Dong, Kyung Rae; Kim, Kwang Cheol

2016-01-01

In this study, the automatic exposure control (AEC) modes of tube current (SIEMENSCare Dose 4D and GE AEC mode) that CT manufacturers are using was applied to neck, chest and abdomen in order to determine the difference in the respective dose parameters (CTDIvol, DLP and mSv) resulting from the dose reduction. Equipment in use at C university adopted Care Dose 4D of Siemens and AEC mode of General Electric (GE), and the x-ray exposure conditions were adjusted to be as identical as possible between the experiments. For the assessment of the dose reduction, the differences between the doses with and without the use of the tube current AEC mode by the respective manufacturer were measured for each body part including neck, chest and abdomen of a human phantom, Rando Phantom (Art-200x, Fluke Biomedical, USA). First, the assessment of SIEMENS-Care Dose 4D yielded the following results. At the neck, the automatic exposure control resulted in a 3.3% reduction in CTDIvol and DLP, and a 3% reduction in the effective dose, mSv, compared to manual exposure control. The automatic exposure control at the chest displayed the reduction in CTDIvol and DLP by 25.5%, and in the effective dose, mSv, by 25.4% compared to the manual exposure control. In case of abdomen, CTDIvol and DLP were shown to be reduced by 16%, and the effective dose (mSv) by 16.3% under the automatic exposure control compared to the manual exposure. Second, the assessment results of GE AEC mode are as follows. The automatic exposure control at the neck resulted in a 45.1% reduction in CTDIvol and DLP, and a 44.7% reduction in the effective dose (mSv) in comparison to the manual exposure control. At the chest, the automatic exposure control displayed a 47.6% reduction in CTDIvol and DLP, and a 47.5% reduction in the effective dose, mSv, compared to the manual exposure control. At the abdomen, it was shown that CTDIvol and DLP were reduced by 26.9%, and the effective dose (mSv) by 26.8% under the automatic

Feasibility Test with a STS304 tube of the Eddy Current Test using a Bobbin Probe for the SMART SG Tube Inspection

International Nuclear Information System (INIS)

Lee, Yoon Sang; Jung, Hyun Kyu; Choung, Yun Hang

2010-01-01

The SMART SG tubes will be made of Alloy 690. The outside diameter will be 17 mm and the thickness will be 2.5 mm. They will be assembled helically around, and their innermost diameter will be about 600 mm and the total length will be about 32 meters. For the sake of safety, SMART SG tubes are designed for use with thick tubes such as 2.5 mm thickness compared to about 1 mm thickness of normal Korean standard pressurized water reactor tubes. Due to using thick tubes such as the 2.5 mm varieties, it was doubted that the Eddy Current Testing Method (ECT) would be a feasible method. Therefore we are trying to check the feasibility of the ECT using the substitute material STS304 tube instead of Alloy 690 tubes with the bobbin type ECT probe. The previous paper reported the feasibility of the ECT using modeling, but this paper will report the preliminary experimental results and comparison with the previous results of the modeling for the STS304 tube

Volume of interest CBCT and tube current modulation for image guidance using dynamic kV collimation

Energy Technology Data Exchange (ETDEWEB)

Parsons, David, E-mail: david.parsons@dal.ca, E-mail: james.robar@nshealth.ca [Department of Physics and Atmospheric Science, Dalhousie University, 5820 University Avenue, Halifax, Nova Scotia B3H 1V7 (Canada); Robar, James L., E-mail: david.parsons@dal.ca, E-mail: james.robar@nshealth.ca [Department of Radiation Oncology and Department of Physics and Atmospheric Science, Dalhousie University, 5820 University Avenue, Halifax, Nova Scotia B3H 1V7 (Canada)

2016-04-15

Purpose: The focus of this work is the development of a novel blade collimation system enabling volume of interest (VOI) CBCT with tube current modulation using the kV image guidance source on a linear accelerator. Advantages of the system are assessed, particularly with regard to reduction and localization of dose and improvement of image quality. Methods: A four blade dynamic kV collimator was developed to track a VOI during a CBCT acquisition. The current prototype is capable of tracking an arbitrary volume defined by the treatment planner for subsequent CBCT guidance. During gantry rotation, the collimator tracks the VOI with adjustment of position and dimension. CBCT image quality was investigated as a function of collimator dimension, while maintaining the same dose to the VOI, for a 22.2 cm diameter cylindrical water phantom with a 9 mm diameter bone insert centered on isocenter. Dose distributions were modeled using a dynamic BEAMnrc library and DOSXYZnrc. The resulting VOI dose distributions were compared to full-field CBCT distributions to quantify dose reduction and localization to the target volume. A novel method of optimizing x-ray tube current during CBCT acquisition was developed and assessed with regard to contrast-to-noise ratio (CNR) and imaging dose. Results: Measurements show that the VOI CBCT method using the dynamic blade system yields an increase in contrast-to-noise ratio by a factor of approximately 2.2. Depending upon the anatomical site, dose was reduced to 15%–80% of the full-field CBCT value along the central axis plane and down to less than 1% out of plane. The use of tube current modulation allowed for specification of a desired SNR within projection data. For approximately the same dose to the VOI, CNR was further increased by a factor of 1.2 for modulated VOI CBCT, giving a combined improvement of 2.6 compared to full-field CBCT. Conclusions: The present dynamic blade system provides significant improvements in CNR for the same

Data analysis algorithms for flaw sizing based on eddy current rotating probe examination of steam generator tubes

International Nuclear Information System (INIS)

Bakhtiari, S.; Elmer, T.W.

2009-01-01

Computer-aided data analysis tools can help improve the efficiency and reliability of flaw sizing based on nondestructive examination data. They can further help produce more consistent results, which is important for both in-service inspection applications and for engineering assessments associated with steam generator tube integrity. Results of recent investigations at Argonne on the development of various algorithms for sizing of flaws in steam generator tubes based on eddy current rotating probe data are presented. The research was carried out as part of the activities under the International Steam Generator Tube Integrity Program (ISG-TIP) sponsored by the U.S. Nuclear Regulatory Commission. A computer-aided data analysis tool has been developed for off-line processing of eddy current inspection data. The main objectives of the work have been to a) allow all data processing stages to be performed under the same user interface, b) simplify modification and testing of signal processing and data analysis scripts, and c) allow independent evaluation of viable flaw sizing algorithms. The focus of most recent studies at Argonne has been on the processing of data acquired with the +Point probe, which is one of the more widely used eddy current rotating probes for steam generator tube examinations in the U.S. The probe employs a directional surface riding differential coil, which helps reduce the influence of tubing artifacts and in turn helps improve the signal-to-noise ratio. Various algorithms developed under the MATLAB environment for the conversion, segmentation, calibration, and analysis of data have been consolidated within a single user interface. Data acquired with a number of standard eddy current test equipment are automatically recognized and converted to a standard format for further processing. Because of its modular structure, the graphical user interface allows user-developed routines to be easily incorporated, modified, and tested independent of the

High temperature ceramic-tubed reformer

Science.gov (United States)

Williams, Joseph J.; Rosenberg, Robert A.; McDonough, Lane J.

1990-03-01

The overall objective of the HiPHES project is to develop an advanced high-pressure heat exchanger for a convective steam/methane reformer. The HiPHES steam/methane reformer is a convective, shell and tube type, catalytic reactor. The use of ceramic tubes will allow reaction temperature higher than the current state-of-the-art outlet temperatures of about 1600 F using metal tubes. Higher reaction temperatures increase feedstock conversion to synthesis gas and reduce energy requirements compared to currently available radiant-box type reformers using metal tubes. Reforming of natural gas is the principal method used to produce synthesis gas (primarily hydrogen and carbon monoxide, H2 and CO) which is used to produce hydrogen (for refinery upgrading), methanol, as well as several other important materials. The HiPHES reformer development is an extension of Stone and Webster's efforts to develop a metal-tubed convective reformer integrated with a gas turbine cycle.

Field-aligned current density versus electric potential characteristics for magnetospheric flux tubes

International Nuclear Information System (INIS)

Lemaire, J.; Scherer, M.

1983-01-01

The field-aligned current density (Jsub(tot)) is a non-linear function of the applied potential difference (phi) between the ionosphere and the magnetosphere. This nonlinear function has been calculated for plasma boundary conditions typical in a dayside cusp magnetic flux tube. The J-characteristic of such a flux tube changes when the temperatures of the warm magnetospheric electrons and of the cold ionospheric electrons are modified; it changes also when the relative density of the warm plasma is modified; the presence of trapped secondary electrons changes also the J-characteristic. The partial currents contributed by the warm and cold electrons, and by warm and cold ions are illustrated. The dynamic characteristic of an electric circuit depends on the static characteristic of each component of the sytem: i.e. the resistive ionosphere, the return current region, and the region of particle precipitation whose field-aligned current/voltage characteristics have been studied in this article

SU-F-J-39: Dose Reduction Strategy Using Attenuation-Based Tube Current Modulation Method in CBCT for IGRT

Energy Technology Data Exchange (ETDEWEB)

Son, K; Lee, H; Kim, C; Cho, S [KAIST, Daejeon (Korea, Republic of); Kim, J [Yonsei Cancer Center, Seoul (Korea, Republic of)

2016-06-15

Purpose: To reduce radiation dose to the patients, tube current modulation (TCM) method has been actively used in diagnostic CT systems. However, TCM method has not yet been applied to a kV-CBCT system on a LINAC machine. The purpose of this study is to investigate whether the use of TCM method is desirable in kV-CBCT system for IGRT. We have developed an attenuation-based tube current modulation (a-TCM) method using the prior knowledge of treatment CT image of a patient. Methods: Patients go through a diagnostic CT scan for RT planning; therefore, using this prior information of CT images, one can estimate the total attenuation of an x-ray through the patient body in a CBCT setting for radiation therapy. We performed a numerical study incorporating major factors into account such as polychromatic x-ray, scatter, noise, and bow-tie filter to demonstrate that a-TCM method can produce equivalent quality of images at reduced imaging radiation doses. Using the CT projector program, 680 projection images of the pediatric XCAT phantom were obtained both in conventional scanning condition, i.e., without modulating the tube current, and in the proposed a-TCM scanning condition. FDK reconstruction algorithm was used for image reconstruction, and the organ dose due to imaging radiation has been calculated in both cases and compared using GATE/Geant4 simulation toolkit. Results: Reconstructed CT images in the a-TCM method showed similar SSIM values and noise properties to the reference images acquired by the conventional CBCT. In addition, reduction of organ doses ranged from 12% to 27%. Conclusion: We have successfully demonstrated the feasibility and dosimetric merit of the a-TCM method for kV-CBCT, and envision that it can be a useful option of CBCT scanning that provides patient dose reduction without degrading image quality.

Effect of x-ray tube current on the accuracy of cerebral perfusion parameters obtained by CT perfusion studies

International Nuclear Information System (INIS)

Murase, Kenya; Nanjo, Takafumi; Ii, Satoshi; Miyazaki, Shohei; Hirata, Masaaki; Sugawara, Yoshifumi; Kudo, Masayuki; Sasaki, Kousuke; Mochizuki, Teruhito

2005-01-01

The purpose of this study was to investigate the effect of x-ray tube current on the accuracy of cerebral perfusion parameters obtained by CT perfusion studies using multi-detector row CT (MDCT). Following the standard CT perfusion study protocol, continuous (cine) scans (1 s/rotation x 60 s) consisting of four 5 mm thick contiguous slices were performed using an MDCT scanner with a tube voltage of 80 kVp and a tube current of 200 mA. We generated the simulated images with tube currents of 50 mA, 100 mA and 150 mA by adding the corresponding noise to the raw scan data of the original image acquired above using a noise simulation tool. From the original and simulated images, we generated the functional images of cerebral blood flow (CBF), cerebral blood volume (CBV) and mean transit time (MTT) in seven patients with cerebrovascular disease, and compared the correlation coefficients (CCs) between the perfusion parameter values obtained from the original and simulated images. The coefficients of variation (CVs) in the white matter were also compared. The CC values deteriorated with decreasing tube current. There was a significant difference between 50 mA and 100 mA for all perfusion parameters. The CV values increased with decreasing tube current. There were significant differences between 50 mA and 100 mA and between 100 mA and 150 mA for CBF. For CBV and MTT, there was also a significant difference between 150 mA and 200 mA. This study will be useful for understanding the effect of x-ray tube current on the accuracy of cerebral perfusion parameters obtained by CT perfusion studies using MDCT, and for selecting the tube current

Scale Thickness Measurement of Steam Generator Tubing Using Eddy Current Signal of Bobbin Coil

International Nuclear Information System (INIS)

Kim, Chang Soo; Um, Ki Soo; Kim, Jae Dong

2012-01-01

Steam generator is one of the major components of nuclear power plant and steam generator tubes are the pressure boundary between primary and secondary side, which makes them critical for nuclear safety. As the operating time of nuclear power plant increases, not only damage mechanisms but also scaled deposits on steam generator tubes are known to be problematic causing tube support flow hole blockage and heat fouling. The ability to assess the extent and location of scaled deposits on tubes became essential for management and maintenance of steam generator and eddy current bobbin data can be utilized to measure thickness of scale on tubes. In this paper, tube reference standards with various thickness of scaled deposit has been set up to provide information about the overall deposit condition of steam generator tubes, providing essential tool for steam generator management and maintenance to predict and prevent future damages. Also, methodology to automatically measure scale thickness on tubes has been developed and applied to field data to estimate overall scale amount.

Current microbiology of percutaneous endoscopic gastrostomy tube (PEG tube) insertion site infections in patients with cancer.

Science.gov (United States)

Rolston, Kenneth V I; Mihu, Coralia; Tarrand, Jeffrey J

2011-08-01

Percutaneous endoscopic gastrostomy (PEG) is frequently used to provide enteral access in cancer patients who are unable to swallow. Infection is an important complication in this setting. Current microbiological data are needed to guide infection prevention and treatment strategies. The microbiological records of our institution (a 550-bed comprehensive cancer center) were retrospectively reviewed over an 8-month study period in order to identify patients who developed PEG tube insertion site infections, and review their microbiological details and susceptibility/resistance data. Fifty-eight episodes of PEG tube insertion site infections were identified. Of these, 31 (53%) were monomicrobial, and the rest were polymicrobial. The most common organisms isolated were Candida species, Staphylococcus aureus, and Pseudomonas aeruginosa. All infections were local (cellulitis, complicated skin, and skin structure infections including abdominal wall abscess) with no cases of concomitant bacteremia being documented. Most of the organisms isolated were susceptible to commonly used antimicrobial agents, although some quinolone-resistant and some multidrug-resistant organisms were isolated. This retrospective study provides descriptive data regarding PEG tube insertion site infections. These data have helped us update institutional guidelines for infection prevention and treatment as part of our focus on antimicrobial stewardship.

Experimental study of the processes accompanying argon breakdown in a long discharge tube at a reduced pressure

Energy Technology Data Exchange (ETDEWEB)

Meshchanov, A. V.; Ionikh, Yu. Z., E-mail: y.ionikh@spbu.ru; Shishpanov, A. I.; Kalinin, S. A. [St. Petersburg State University (Russian Federation)

2016-10-15

Results are presented from experimental studies of the breakdown stage of a low-pressure discharge (1 and 5 Torr) in a glass tube the length of which (75 cm) is much larger than its diameter (2.8 cm). Breakdowns occurred under the action of positive voltage pulses with an amplitude of up to 9.4 kV and a characteristic rise time of 2–50 μs. The discharge current in the steady-state mode was 10–120 mA. The electrode voltage, discharge current, and radiation from the discharge gap were detected simultaneously. The dynamic breakdown voltage was measured, the prebreakdown ionization wave was recorded, and its velocity was determined. The dependence of the discharge parameters on the time interval between voltage pulses (the socalled “memory effect”) was analyzed. The memory effect manifests itself in a decrease or an increase in the breakdown voltage and a substantial decrease in its statistical scatter. The time interval between pulses in this case can reach 0.5 s. The effect of illumination of the discharge tube with a light source on the breakdown was studied. It is found that the irradiation of the anode region of the tube by radiation with wavelengths of ≤500 nm substantially reduces the dynamic breakdown voltage. Qualitative explanations of the obtained results are offered.

Estimating patient dose from CT exams that use automatic exposure control: Development and validation of methods to accurately estimate tube current values.

Science.gov (United States)

McMillan, Kyle; Bostani, Maryam; Cagnon, Christopher H; Yu, Lifeng; Leng, Shuai; McCollough, Cynthia H; McNitt-Gray, Michael F

2017-08-01

The vast majority of body CT exams are performed with automatic exposure control (AEC), which adapts the mean tube current to the patient size and modulates the tube current either angularly, longitudinally or both. However, most radiation dose estimation tools are based on fixed tube current scans. Accurate estimates of patient dose from AEC scans require knowledge of the tube current values, which is usually unavailable. The purpose of this work was to develop and validate methods to accurately estimate the tube current values prescribed by one manufacturer's AEC system to enable accurate estimates of patient dose. Methods were developed that took into account available patient attenuation information, user selected image quality reference parameters and x-ray system limits to estimate tube current values for patient scans. Methods consistent with AAPM Report 220 were developed that used patient attenuation data that were: (a) supplied by the manufacturer in the CT localizer radiograph and (b) based on a simulated CT localizer radiograph derived from image data. For comparison, actual tube current values were extracted from the projection data of each patient. Validation of each approach was based on data collected from 40 pediatric and adult patients who received clinically indicated chest (n = 20) and abdomen/pelvis (n = 20) scans on a 64 slice multidetector row CT (Sensation 64, Siemens Healthcare, Forchheim, Germany). For each patient dataset, the following were collected with Institutional Review Board (IRB) approval: (a) projection data containing actual tube current values at each projection view, (b) CT localizer radiograph (topogram) and (c) reconstructed image data. Tube current values were estimated based on the actual topogram (actual-topo) as well as the simulated topogram based on image data (sim-topo). Each of these was compared to the actual tube current values from the patient scan. In addition, to assess the accuracy of each method in estimating

Individualized radiation dose control in 256-slice CT coronary angiography (CTCA) in retrospective ECG-triggered helical scans: Using a measure of body size to adjust tube current selection

Energy Technology Data Exchange (ETDEWEB)

Li, Jing-Lei, E-mail: lijinglei80@126.com [Department of Radiology, Guangdong Academy of Medical Sciences, Guangdong General Hospital, 106 Zhongshan Er Road, Guangzhou 510080 (China); Huang, Mei-Ping, E-mail: huang_meiping@yahoo.com.cn [Department of Radiology, Guangdong Academy of Medical Sciences, Guangdong General Hospital, 106 Zhongshan Er Road, Guangzhou 510080 (China); Liang, Chang-Hong, E-mail: cjr.lchh@vip.163.com [Department of Radiology, Guangdong Academy of Medical Sciences, Guangdong General Hospital, 106 Zhongshan Er Road, Guangzhou 510080 (China); Zhao, Zhen-Jun, E-mail: junabc2006@hotmail.com [Department of Radiology, Guangdong Academy of Medical Sciences, Guangdong General Hospital, 106 Zhongshan Er Road, Guangzhou 510080 (China); Liu, Hui, E-mail: liuhuijiujiu@gmail.com [Department of Radiology, Guangdong Academy of Medical Sciences, Guangdong General Hospital, 106 Zhongshan Er Road, Guangzhou 510080 (China); Cui, Yan-Hai, E-mail: yanhai_cui@126.com [Department of Radiology, Guangdong Academy of Medical Sciences, Guangdong General Hospital, 106 Zhongshan Er Road, Guangzhou 510080 (China); Liu, Qi-Shun, E-mail: liuqishun@yeah.net [Department of Radiology, Guangdong Academy of Medical Sciences, Guangdong General Hospital, 106 Zhongshan Er Road, Guangzhou 510080 (China); Zhang, Jin-E., E-mail: zhjine@yahoo.com.cn [Department of Radiology, Guangdong Academy of Medical Sciences, Guangdong General Hospital, 106 Zhongshan Er Road, Guangzhou 510080 (China); Yang, Lin, E-mail: yanglin001517@163.com [Department of Radiology, Guangdong Academy of Medical Sciences, Guangdong General Hospital, 106 Zhongshan Er Road, Guangzhou 510080 (China); Ivanc, Thomas B., E-mail: Thomas.ivanc@philips.com [CT Clinical Science, Philips Healthcare, Highland Heights, OH (United States); Yanof, Jeffrey H., E-mail: Jeffrey.yanof@philips.com [CT Clinical Science, Philips Healthcare, Highland Heights, OH (United States)

2012-11-15

Purpose: To reduce radiation dose for retrospective ECG-triggered helical 256-slice CTCA by determining an optimal body size index to prospectively adjust tube current. Methods: 102 consecutive patients with suspected CAD underwent retrospective ECG-triggered CTCA using 256-slice CT scanner. Six body size indexes including BMI, nipple level (NL) bust, thoracic anteroposterior diameter at NL, chest circumference (CC) at NL, left main and right coronary artery (RCA) origin level were measured and their correlation with noise was evaluated using linear regression. An equation was developed to use this index to adjust tube current. Additional 102 consecutive patients were scanned with the index-based mA s adjustment. A t-test for independent samples was used to compare radiation dose levels with and without the index-based mA s selection method. Results: Linear regression indicated that CC RCA had the best correlation with noise (R{sup 2} = 0.603). Effective radiation dose was reduced from 16.6 {+-} 0.9 to 9.8 {+-} 2.7 mSv (p < 0.01), i.e. 40.9% lower dose with the CC RCA-adapted tube current method. The image quality scores indicated no significant difference with and without the size-based mA s selection method. Conclusion: An accessible measure of body size, such as CC RCA, can be used to adapt tube current for individualized radiation dose control.

Individualized radiation dose control in 256-slice CT coronary angiography (CTCA) in retrospective ECG-triggered helical scans: Using a measure of body size to adjust tube current selection

International Nuclear Information System (INIS)

Li, Jing-Lei; Huang, Mei-Ping; Liang, Chang-Hong; Zhao, Zhen-Jun; Liu, Hui; Cui, Yan-Hai; Liu, Qi-Shun; Zhang, Jin-E.; Yang, Lin; Ivanc, Thomas B.; Yanof, Jeffrey H.

2012-01-01

Purpose: To reduce radiation dose for retrospective ECG-triggered helical 256-slice CTCA by determining an optimal body size index to prospectively adjust tube current. Methods: 102 consecutive patients with suspected CAD underwent retrospective ECG-triggered CTCA using 256-slice CT scanner. Six body size indexes including BMI, nipple level (NL) bust, thoracic anteroposterior diameter at NL, chest circumference (CC) at NL, left main and right coronary artery (RCA) origin level were measured and their correlation with noise was evaluated using linear regression. An equation was developed to use this index to adjust tube current. Additional 102 consecutive patients were scanned with the index-based mA s adjustment. A t-test for independent samples was used to compare radiation dose levels with and without the index-based mA s selection method. Results: Linear regression indicated that CC RCA had the best correlation with noise (R 2 = 0.603). Effective radiation dose was reduced from 16.6 ± 0.9 to 9.8 ± 2.7 mSv (p < 0.01), i.e. 40.9% lower dose with the CC RCA-adapted tube current method. The image quality scores indicated no significant difference with and without the size-based mA s selection method. Conclusion: An accessible measure of body size, such as CC RCA, can be used to adapt tube current for individualized radiation dose control.

Eddy-current tests on operational evaluation of steam generator tubes in nuclear power plants

International Nuclear Information System (INIS)

Lopez, Luiz Antonio Negro Martin; Ting, Daniel Kao Sun

2000-01-01

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

Lunar Lava Tube Sensing

Science.gov (United States)

York, Cheryl Lynn; Walden, Bryce; Billings, Thomas L.; Reeder, P. Douglas

1992-01-01

Large (greater than 300 m diameter) lava tube caverns appear to exist on the Moon and could provide substantial safety and cost benefits for lunar bases. Over 40 m of basalt and regolith constitute the lava tube roof and would protect both construction and operations. Constant temperatures of -20 C reduce thermal stress on structures and machines. Base designs need not incorporate heavy shielding, so lightweight materials can be used and construction can be expedited. Identification and characterization of lava tube caverns can be incorporated into current precursor lunar mission plans. Some searches can even be done from Earth. Specific recommendations for lunar lava tube search and exploration are (1) an Earth-based radar interferometer, (2) an Earth-penetrating radar (EPR) orbiter, (3) kinetic penetrators for lunar lava tube confirmation, (4) a 'Moon Bat' hovering rocket vehicle, and (5) the use of other proposed landers and orbiters to help find lunar lava tubes.

Application of numerical analysis techniques to eddy current testing for steam generator tubes

International Nuclear Information System (INIS)

Morimoto, Kazuo; Satake, Koji; Araki, Yasui; Morimura, Koichi; Tanaka, Michio; Shimizu, Naoya; Iwahashi, Yoichi

1994-01-01

This paper describes the application of numerical analysis to eddy current testing (ECT) for steam generator tubes. A symmetrical and three-dimensional sinusoidal steady state eddy current analysis code was developed. This code is formulated by future element method-boundary element method coupling techniques, in order not to regenerate the mesh data in the tube domain at every movement of the probe. The calculations were carried out under various conditions including those for various probe types, defect orientations and so on. Compared with the experimental data, it was shown that it is feasible to apply this code to actual use. Furthermore, we have developed a total eddy current analysis system which consists of an ECT calculation code, an automatic mesh generator for analysis, a database and display software for calculated results. ((orig.))

Effect of drag-reducing polymers on Tubing Performance Curve (TPC) in vertical gas-liquid flows

NARCIS (Netherlands)

Shoeibi Omrani, P.; Veltin, J.; Turkenburg, D.H.

2014-01-01

This paper discusses the effect of drag reducing polymers on the Tubing Performance Curve (TPC) of vertical air-water flows at near atmospheric conditions. The effect of polymer concentration, liquid and gas flow rates on the pressure drop curve (Tubing Performance Curve) was investigated

Self-field AC losses and critical currents in multi-tube Ag-Bi-2223 conductors

Energy Technology Data Exchange (ETDEWEB)

Ciszek, M; Ashworth, S P; Campbell, A M [IRC in Superconductivity, University of Cambridge, Madingley Road, Cambridge CB3 0HE (United Kingdom); James, M P; Glowacki, B A [IRC in Superconductivity, University of Cambridge, Madingley Road, Cambridge CB3 0HE (United Kingdom); Department of Materials Science and Metallurgy, University of Cambridge, Pembroke Street, Cambridge CB2 3QZ (United Kingdom); Garre, R; Conti, S [Centro Ricerche Europa Metalli, Fornaci di Barga, LU (Italy)

1996-05-01

The purpose of this work was to investigate the influence of different technological treatments of silver sheathed Bi-2223 tapes on the critical current density and the AC transport losses. The tapes were produced using the 'tube-in-tube' technique, by including a silver rod in the centre of the superconducting powder during packing of the silver tube. The aim of the process is to increase the silver to superconductor surface area and thus also the alignment at the centre of the conductor ceramic core. AC transport losses were measured by means of an electrical method using sinusoidally varying currents in the frequency range 30-180 Hz. In this range the power losses are hysteretic. The measured variation in losses from those predicted by a critical state model is attributed to the complex geometry of superconducting regions existing in these tapes. (author)

Modeling of tube current modulation methods in computed tomography dose calculations for adult and pregnant patients

International Nuclear Information System (INIS)

Caracappa, Peter F.; Xu, X. George; Gu, Jianwei

2011-01-01

The comparatively high dose and increasing frequency of computed tomography (CT) examinations have spurred the development of techniques for reducing radiation dose to imaging patients. Among these is the application of tube current modulation (TCM), which can be applied either longitudinally along the body or rotationally along the body, or both. Existing computational models for calculating dose from CT examinations do not include TCM techniques. Dose calculations using Monte Carlo methods have been previously prepared for constant-current rotational exposures at various positions along the body and for the principle exposure projections for several sets of computational phantoms, including adult male and female and pregnant patients. Dose calculations from CT scans with TCM are prepared by appropriately weighting the existing dose data. Longitudinal TCM doses can be obtained by weighting the dose at the z-axis scan position by the relative tube current at that position. Rotational TCM doses are weighted using the relative organ doses from the principle projections as a function of the current at the rotational angle. Significant dose reductions of 15% to 25% to fetal tissues are found from simulations of longitudinal TCM schemes to pregnant patients of different gestational ages. Weighting factors for each organ in rotational TCM schemes applied to adult male and female patients have also been found. As the application of TCM techniques becomes more prevalent, the need for including TCM in CT dose estimates will necessarily increase. (author)

Reduced program of inspection by induced currents for condenser of Embalse nuclear power plant

International Nuclear Information System (INIS)

Obrutsky, L.; Mendonca, H.

1986-01-01

In this work it's presented a reduced inspection in service program by the technique of induced currents to the turbine condenser of Embalse's Power Plant (Cordoba). The authors based its elaboration on the results obtained in the exam of a small number of tubes and on experience obtained through four inspections in the condensers of Atucha I Power Plant, through mathematical models of oxygen and ammoniac distribution in both Power Plants, and its experimental verification in the case of Atucha I. This program improves the quality of inspection thereby reducing time, equipment and personnel employed. (C.M.) [pt

Performance demonstration tests for eddy current inspection of steam generator tubing

International Nuclear Information System (INIS)

Kurtz, R.J.; Heasler, P.G.; Anderson, C.M.

1996-05-01

This report describes the methodology and results for development of performance demonstration tests for eddy current (ET) inspection of steam generator tubes. Statistical test design principles were used to develop the performance demonstration tests. Thresholds on ET system inspection performance were selected to ensure that field inspection systems would have a high probability of detecting and and correctly sizing tube degradation. The technical basis for the ET system performance thresholds is presented in detail. Statistical test design calculations for probability of detection and flaw sizing tests are described. A recommended performance demonstration test based on the design calculations is presented. A computer program for grading the probability of detection portion of the performance demonstration test is given

Performance demonstration tests for eddy current inspection of steam generator tubing

Energy Technology Data Exchange (ETDEWEB)

Kurtz, R.J.; Heasler, P.G.; Anderson, C.M.

1996-05-01

This report describes the methodology and results for development of performance demonstration tests for eddy current (ET) inspection of steam generator tubes. Statistical test design principles were used to develop the performance demonstration tests. Thresholds on ET system inspection performance were selected to ensure that field inspection systems would have a high probability of detecting and and correctly sizing tube degradation. The technical basis for the ET system performance thresholds is presented in detail. Statistical test design calculations for probability of detection and flaw sizing tests are described. A recommended performance demonstration test based on the design calculations is presented. A computer program for grading the probability of detection portion of the performance demonstration test is given.

Standardized procedure for eddy-current testing of stainless steel, thin-walled nuclear fuel element cladding tubes

Energy Technology Data Exchange (ETDEWEB)

Barat, P; Raj, B; Bhattacharya, D K [Reactor Research Centre, Kalpakkam (India)

1982-10-01

Thin-walled nuclear fuel cladding tubes made of AISI 316 stainless steel have been examined by eddy-current testing. Standardization of the procedures has required investigations on optimizing the test frequency, finding a method to locate a defect with respect to the probe reference end, and the use of standard defects and sequential metallography of natural defects detected by eddy-current testing, to understand the influence of the nature of defects on the impedance output signals. Test frequency and method of locating the defect were optimized by the use of standard defects made by machining in reference cladding tubes. Subsequent metallography of natural defects detected by eddy-current testing revealed mainly clusters of inclusions but also other types of defects. The effect of the distribution of inclusions along the length of the tube on the impedance output is discussed.

Regression analysis of pulsed eddy current signals for inspection of steam generator tube support structures

International Nuclear Information System (INIS)

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

2015-01-01

Nuclear steam generator (SG) support structure degradation and fouling can result in damage to SG tubes and loss of SG efficiency. Conventional eddy current technology is extensively used to detect cracks, frets at supports and other flaws, but has limited capabilities in the presence of multiple degradation modes or fouling. Pulsed eddy current (PEC) combined with principal components analysis (PCA) and multiple linear regression models was examined for the inspection of support structure degradation and SG tube off-centering with the goal of extending results to include additional degradation modes. (author)

Combination of U.V.-B and ozone reduces pollen tube growth more than either stress alone

International Nuclear Information System (INIS)

Feder, W.A.; Shrier, R.

1990-01-01

The rate of in vitro Nicotiana tabacum L. “Bel-W3” pollen tube growth was reduced 62 and 44%, respectively, when pollen tubes were exposed to 120 ppb ozone (O 3 ) for 3 hr or 300 μW/cm 2 ultraviolet-B (u.v.-B) radiation for 30 min. Petunia hybrida Vilm. “White Cascade” pollen tube growth was reduced 34 and 59%, respectively, upon exposure to O 3 or u.v.-B at the above doses. The combination of u.v.-B at 300 μW/cm 2 for 30 min, followed by O 3 at 120 ppb for 3 hr, reduced pollen tube growth by 79% for “Bel-W3” and 75% for “White Cascade”. The effect appeared to be additive, implying that different target areas may be affected by the two stressors. In the Northeast, plants are exposed to both u.v.-B and O 3 during the normal growing season. This may result in an unexpectedly higher stress on the reproductive system than had been previously suspected based on these two stressors acting individually. (author)

Evaluation of the inner wall axial cracks of steam generator tubes by eddy current test

International Nuclear Information System (INIS)

Hur, Do Haeng; Choi, Myung Sik; Lee, Doek Hyun; Han, Jung Ho

2001-01-01

For the enhancement of ECT reliability on the primary water stress corrosion cracks of nuclear steam generator tubes, it is important to comprehend the signal characteristics on crack morphology and to select an appropriate probe type. In this paper, the sizing accuracy and the detectability for the inner wall axial cracks of tubes were quantitatively evaluated using the electric discharge machined notches and the corrosion cracks which were developed on the operating steam generator tubes. The difference of eddy current signal characteristics between pancake and axial coil were also investigated. The results obtained from this study provide a useful information for more precise evaluation on the inner wall axial cracks of steam generator tubes.

Enhanced methods for operating refueling station tube-trailers to reduce refueling cost

Science.gov (United States)

Elgowainy, Amgad; Reddi, Krishna

2017-08-22

A method and apparatus are provided for operating a refueling station including source tube-trailers and at least one compressor to reduce refueling cost. The refueling station includes a gaseous fuel supply source including a plurality of tanks on a tube trailer coupled to a first control unit, and high pressure buffer storage having predefined capacity coupled to a second control unit and the first tanks by a pressure control valve and the first control unit, and at least one compressor. The refueling station is operated at different modes depending on a state of the refueling station at the beginning of each operational mode. The refueling system is assessed at the end of each operational mode to identify the state of the system and select a next mode of operation. The operational modes include consolidating hydrogen, or any gaseous fuel, within the tubes mounted on the trailer.

Wavelets transforms and fuzzy logic in the eddy-current inspection of nuclear power plants steam generator tubes

International Nuclear Information System (INIS)

Lopez, Luiz Antonio Negro Martin

2002-01-01

Nuclear power plants steam generators around the world have presented early damage history in their tubes, caused either by design errors or by inappropriate operation, which besides reducing the availability and the safety of the nuclear power plants it also generates heavy economical burden. To monitor the steam generators operational condition, the Eddy Current testing of their tubes is the non destructive method used to detect, localize, classify and to size the defects. The inspection is performed by inserting probes with coils in the tubes generating a signal correlated to the defect. These signals produced by the probe electric circuit are composed by the resistance and the inductive components which can be combined to produce a Lissajous figure in the complex plane. However, Eddy-Current signals contain noise which induce subjectivity inducing to errors in the inspector diagnosis. It is not uncommon to have different diagnosis from two inspectors about the same signal. The present work has the objective of supplying a methodology to analyze the signals which could help the inspector in the difficult task of interpreting the Eddy Current signals. It is proposed a method to remove the noise based on Wavelets Transforms. It is also proposed a normalization in the signal phase angle measurements. Furthermore, two additional characteristics are also studied, namely: the signal amplitudes and the widths of the Lissajous petals. The use of a Fuzzy Logic based inference engine is also developed and its use is demonstrated to be viable. The defects studied in this work are those which produces volumetric changes in the material. In order to test the proposed methodology, several artificial defects were produced in tubes using different types of materials like: brass, 316L stainless steel and Inconel 600 to produce a experimental data base. An Eddy-Current inspection equipment, the MIZ-17ET was used. Around 1000 time series signals of defects were acquired through

Motor Challenge: Improving Efficiency of Tube Drawing Bench Reduces Energy Use by 34%

International Nuclear Information System (INIS)

Erika Ericksen

1999-01-01

The case study reveals how a manufacturer of high-precision, small-diameter steel tubing has reduced energy consumption and realized considerable electrical, labor, and materials cost savings with a more energy-efficient motor

Determination of semi-reducing layer and applied stress through spectra emitted by an X-ray tube

International Nuclear Information System (INIS)

Santos, Josilene C.; Gonzalez, Alejandro H.L.; Terini, Ricardo A.; Costa, Paulo R.

2016-01-01

This work describes a method for assessment of half value layer (HVL) and peak tube voltage (kVp) by means of experimental x-ray spectra measured using a CdTe detector. The work also evaluated spectrometry parameters such as dead time and count rate, and x-ray tube characteristics that can affect the assessment of these quantities. Two sets of x-ray spectra were measured: A) using Cu filters with different thicknesses and fixed tube current, and B) keeping a fixed Cu filtration and different tube current and, so, ranging the count rates. The spectrometer was energy calibrated using standard radioactive sources. kVp value was estimated by means of experimental measured x-ray spectra, using linear regression in order to search the end point of each spectrum. HVL was estimated after the correction of the measured spectra, using an analytical method implemented using Matlab® software. For comparison, HVL was also determined using a 30 cm"3 ion chamber and high purity Al filters. (author)

Recent Advances in Simulation of Eddy Current Testing of Tubes and Experimental Validations

Science.gov (United States)

Reboud, C.; Prémel, D.; Lesselier, D.; Bisiaux, B.

2007-03-01

Eddy current testing (ECT) is widely used in iron and steel industry for the inspection of tubes during manufacturing. A collaboration between CEA and the Vallourec Research Center led to the development of new numerical functionalities dedicated to the simulation of ECT of non-magnetic tubes by external probes. The achievement of experimental validations led us to the integration of these models into the CIVA platform. Modeling approach and validation results are discussed here. A new numerical scheme is also proposed in order to improve the accuracy of the model.

Evaluation of Eddy Current Signals from the Inner Wall Axial Cracks of Steam Generator Tubes

International Nuclear Information System (INIS)

Choi, Myung Sik; Hur, Do Haeng; Lee, Doek Hyun; Han, Jung Ho; Park, Jung Am

2001-01-01

For the enhancement of ECT reliability on the primary water stress corrosion cracks of nuclear steam generator tubes, of which the occurrence is on the increase, it is important to comprehend the signal characteristics on crack morphology and to select an appropriate probe type. In this paper, the sizing accuracy and the detectability for the inner wall axial cracks of tubes were quantitatively evaluated using the following specimens: the electric discharge machined notches and the corrosion cracks which were developed on the operating steam generator tubes. The difference of eddy current signal characteristics between pancake and axial coil were also Investigated. The results obtained from this study provide a useful information for more precise evaluation on the inner wall axial tracks oi steam generator tubes

A standardized procedure for eddy-current testing of stainless steel, thin-walled nuclear fuel element cladding tubes

International Nuclear Information System (INIS)

Barat, P.; Raj, B.; Bhattacharya, D.K.

1982-01-01

Thin-walled nuclear fuel cladding tubes made of AISI 316 stainless steel have been examined by eddy-current testing. Standardization of the procedures has required investigations on optimizing the test frequency, finding a method to locate a defect with respect to the probe reference end, and the use of standard defects and sequential metallography of natural defects detected by eddy-current testing, to understand the influence of the nature of defects on the impedance output signals. Test frequency and method of locating the defect were optimized by the use of standard defects made by machining in reference cladding tubes. Subsequent metallography of natural defects detected by eddy-current testing revealed mainly clusters of inclusions but also other types of defects. The effect of the distribution of inclusions along the length of the tube on the impedance output is discussed. (author)

Assessment of an organ-based tube current modulation in thoracic computed tomography.

Science.gov (United States)

Matsubara, Kosuke; Sugai, Mai; Toyoda, Asami; Koshida, Haruka; Sakuta, Keita; Takata, Tadanori; Koshida, Kichiro; Iida, Hiroji; Matsui, Osamu

2012-03-08

Recently, specific computed tomography (CT) scanners have been equipped with organ-based tube current modulation (TCM) technology. It is possible that organ-based TCM will replace the conventional dose-reduction technique of reducing the effective milliampere-second. The aim of this study was to determine if organ-based TCM could reduce radiation exposure to the breasts without compromising the image uniformity and beam hardening effect in thoracic CT examinations. Breast and skin radiation doses and the absorbed radiation dose distribution within a single section were measured with an anthropomorphic phantom and radiophotoluminescent glass dosimeters using four approaches to thoracic CT (reference, organ-based TCM, copper shielding, and the combination of the above two techniques, hereafter referred to as the combination technique). The CT value and noise level were measured using the same calibration phantom. Organ-based TCM and copper shielding reduced radiation doses to the breast by 23.7% and 21.8%, respectively. However, the CT value increased, especially in the anterior region, using copper shielding. In contrast, the CT value and noise level barely increased using organ-based TCM. The combination technique reduced the radiation dose to the breast by 38.2%, but greatly increased the absorbed radiation dose from the central to the posterior regions. Moreover, the CT value increased in the anterior region and the noise level increased by more than 10% in the entire region. Therefore, organ-based TCM can reduce radiation doses to breasts with only small increases in noise levels, making it preferable for specific groups of patients, such as children and young women.

Treatment with some anti-inflammatory drugs reduces germ tube formation in Candida albicans strains

Directory of Open Access Journals (Sweden)

Elena Rusu

2014-12-01

Full Text Available Candida albicans is an opportunistic dimorphic fungus that inhabits various host mucosal sites. It can cause both superficial and serious systemic disease. Conversion from the yeast to the hyphal form has been associated with increased virulence and mucosal invasiveness. The aim of this study was to investigate the effect of sodium diclofenac and aspirin on germs tube formation of different Candida albicans strains. Prostaglandins may play an important role in fungal colonization. Nonsteroidal anti-inflammatory drugs are inhibitors of the cyclooxygenase isoenzymes. These drugs specifically block the biosynthesis of mammalian prostaglandins by inhibiting one or both of cyclooxygenase isoenzymes. In tests for germ tube formation sodium diclofenac reduced the filamentation to the 12.5%- 5.1%. In the presence of aspirin the filamentation was reduced up to 85-45% depending on the tested strain. Our results suggest that cyclooxygenase-depending synthesis of fungal prostaglandins is important for morphogenesis and fungal virulence. Inhibitors of cyclooxygenase isoensymes (aspirin and diclofenac are effective in decreasing germ tube formation of Candida albicans.

Influence of tube voltage on CT attenuation, radiation dose, and image quality: phantom study

International Nuclear Information System (INIS)

Li Fengtan; Li Dong; Zhang Yunting

2013-01-01

Objective: To assess the influence of tube current and tube voltage on the CT attenuation, radiation dose, and image quality. Methods: A total of 113 saline solutions with decreasing dilution of contrast medium (370 mg I/ml) was produced. MDCT scan was performed with 15 series of different settings of tube current and tube voltage. CT attenuations with 15 series of different settings were all measured, and influence of tube current and tube voltage on CT attenuations was analyzed. CT dose index (CTDIvol) was recorded. The CT attenuations with different tube voltage and current were compared with one-way ANOVA and Kruskal-Wallis rank sum test. The correlation of CT attenuation with different tube voltage and the influence of tube voltage and current on radiation dose and image quality were tested by correlation analysis. Results: Tube current (250, 200, 150, 100, and 50 mA) had no significant effect on CT attenuation (F = 0.001, 0.008, 0.075, P > 0.05), while tube voltage (120, 100, and 80 kV) had significant effect (H = 17.906, 17.906, 13.527, 20.124, 23.563, P < 0.05). The correlation between CT attenuation and tube voltage was determined with equation: CT attenuatio N_1_0_0 _k_V = 1.561 × CT attenuatio N_1_2_0 _k_v + 4.0818, CT attenuatio N_8_0 _k_v = 1.2131 × CT attenuatio N_1_2_0 _k_v + 0.9283. The influence of tube voltage on radiation dose and image quality was also analyzed, and equations were also obtained: N_1_2_0 -k_v = -5.9771 Ln (D_1_2_0 kv) + 25.412, N_1_0_0 _k_v = -10.544 Ln (D_1_0_0 _k_v) + 36.262, N_8_0 _k_v = -25.326 Ln (D_8_0 _k_v) + 62.816. According to the results of relationship among CT attenuation, radiation dose, and image quality, lower tube voltage with higher tube current can reduce the radiation dose. Conclusions: Lower tube voltage can reduce the radiation dose. However, CT attenuation was influenced, and correction should be done with the equations. (authors)

A review of current knowledge on the effects of hydrogen on the pressure tubes of Ontario Hydro operating reactors

International Nuclear Information System (INIS)

Leger, M.

1982-01-01

Since the occurrence of cracking in Zr-2.5 wt% Nb pressure tubes in Pickering 'A' units 3 and 4 in 1974/75 a great deal of information on the behaviour of hydrogen in pressure tube materials has been generated through research effort by both AECL and Ontario Hydro. In order to use this information effectively and to provide direction and co-ordination for ongoing research, a review of available information and current concerns on hydrogen in pressure tubes was undertaken. The review was divided into two main areas of interest: hydrogen ingress and hydride effects. The uncertainties in the rates of hydrogen ingress into the pressure tubes have been found to be very large. On the basis of current knowledge, predictions of the future behaviour of pressure tubes due to hydride effects are extremely difficult

A comparative Thermal Analysis of conventional parabolic receiver tube and Cavity model tube in a Solar Parabolic Concentrator

Science.gov (United States)

Arumugam, S.; Ramakrishna, P.; Sangavi, S.

2018-02-01

Improvements in heating technology with solar energy is gaining focus, especially solar parabolic collectors. Solar heating in conventional parabolic collectors is done with the help of radiation concentration on receiver tubes. Conventional receiver tubes are open to atmosphere and loose heat by ambient air currents. In order to reduce the convection losses and also to improve the aperture area, we designed a tube with cavity. This study is a comparative performance behaviour of conventional tube and cavity model tube. The performance formulae were derived for the cavity model based on conventional model. Reduction in overall heat loss coefficient was observed for cavity model, though collector heat removal factor and collector efficiency were nearly same for both models. Improvement in efficiency was also observed in the cavity model’s performance. The approach towards the design of a cavity model tube as the receiver tube in solar parabolic collectors gave improved results and proved as a good consideration.

Evaluation of the individual tube current setting in electrocardiogram-gated cardiac computed tomography estimated from plain chest computed tomography using computed tomography automatic exposure control

International Nuclear Information System (INIS)

Kishimoto, Junichi; Sakou, Toshio; Ohta, Yasutoshi

2013-01-01

The aim of this study was to estimate the tube current on a cardiac computed tomography (CT) from a plain chest CT using CT-automatic exposure control (CT-AEC), to obtain consistent image noise, and to optimize the scan tube current by individualizing the tube current. Sixty-five patients (Group A) underwent cardiac CT at fixed tube current. The mAs value for plain chest CT using CT-AEC (AEC value) and cardiac CT image noise were measured. The tube current needed to obtain the intended level of image noise in the cardiac CT was determined from their correlation. Another 65 patients (Group B) underwent cardiac CT with tube currents individually determined from the AEC value. Image noise was compared among Group A and B. Image noise of cardiac CT in Group B was 24.4±3.1 Hounsfield unit (HU) and was more uniform than in Group A (21.2±6.1 HU). The error with the desired image noise of 25 HU was lower in Group B (2.4%) than in Group A (15.2%). Individualized tube current selection based on AEC value thus provided consistent image noise and a scan tube current optimized for cardiac CT. (author)

A Study of Frequency Mixing Approaches for Eddy Current Testing of Steam Generator Tubes

International Nuclear Information System (INIS)

Jung, Hee Jun; Song, Sung Jin; Kim, Chang Hwan; Kim, Dae Kwang

2009-01-01

The multifrequency eddy current testing(ECT) have been proposed various frequency mixing algorithms. In this study, we compare these approaches to frequency mixing of ECT signals from steam generator tubes; time-domain optimization, discrete cosine transform-domain optimization. Specifically, in this study, two different frequency mixing algorithms, a time-domain optimization method and a discrete cosine transform(DCT) optimization method, are investigated using the experimental signals captured from the ASME standard tube. The DCT domain optimization method is computationally fast but produces larger amount of residue.

Improvement of ISI techniques by multi-frequency eddy current testing method for steam generator tube in PWR plant

International Nuclear Information System (INIS)

Endo, Takashi; Kamimura, Takeo; Nishihara, Masatoshi; Araki, Yasuo; Fukui, Shigetaka.

1982-05-01

Eddy current flaw detection techniques are applied to the in-service inspection (ISI) of steam generator tubes in pressurized water reactors (PWR) plant. To improve the reliability and operating efficiency of the plants, efforts are being made to develop eddy current testing methods of various kinds. Multi-frequency eddy current testing method, one of new method, has recently been applied to actual heat exchanger tubes, contributing to the improvement of the detectability and signal evaluation of the ISI. The outline of multi-frequency eddy current testing method and its effects on the improvement of flaw detecting and signal evaluation accuracy are described. (author)

Eddy current and quench loads and stress of SSC collider 4-K liner and the bore tube during magnet quench

International Nuclear Information System (INIS)

Leung, K.K.; Shu, Q.S.

1993-07-01

This paper describes the response of the eddy current and quench loads on a proposed Superconducting SuperCollider 4-K liner system. The liner within a bore tube is designed to remove the radiated power and the photodesorbed gas that impair the beam tube vacuum. The bimetallic liner tube is subjected to cooldown and eddy current loads. The square liner tube is a two-shell laminated Nitronic-40 steel is used for strength and a copper inner layer for low impedance to the image currents. Perforated holes are used to remove the photodesorbed gases for vacuum maintenance. The holes are located in a low-stress area of the liner. Rectangular holes in a four-pole symmetry pattern are required for beam dynamic stability. The liner is conductivity cooled by the round steel bore tube with a 2-mm wall. The copper layer must not be stressed over the yield strength limit because copper properties such as conductivity are known to change when the copper is stressed over yield strength. This analysis will address liner system response under thermal, eddy current, and vaporized liquid helium loads in a quenching dipole magnet

A study on characteristic of glass dosimeter according to grade change of tube current

Energy Technology Data Exchange (ETDEWEB)

Son, Jin Hyun; Kim, Seong Ho; Mun, Hyun Jun; Kim, Lyun Kyun; Son, In Hwa; Kim, Young Jun; Min, Jung Whan [Dept. of Radiological Science, Shingu University, Sungnam (Korea, Republic of); Kim, Ki Won [Dept. of Radiology, Samsung Medical Center, Seoul (Korea, Republic of)

2014-06-15

This study was evaluated the linearity and reproducibility according to dose, and reproducibility according to delay time by changing tube current amount (5 mAs, 10 mAs, 16 mAs, 20 mAs, 25 mAs, 32 mAs respectively, which are low energy radiations) using Glass Dosimeter (GD) and piranha semiconductor dosimeter which are used for measuring exposure dose. Measurements of radiation dose were performed using external detector of piranha 657 which is multi-function QA device (RTI Electronic, Sweden). Conditions of measurement were 80 kVp, SSD 100 and exposure region is 10 cm x 10 cm. Glass dosimeter was exposed to radiation. Twenty-four glass dosimeters were divided into six groups (5 mAs, 10 mAs, 16 mAs, 20 mAs, 25 mAs, 32 mAs respectively), then measured. This study was resulted by measuring the linearity and reproducibility according to change of tube current in low energy field. In dose characteristic of GD, this study could be useful as previous study with regard to dose characteristic according to change of tube voltage in low energy field.

Assessment of an organ‐based tube current modulation in thoracic computed tomography

Science.gov (United States)

Sugai, Mai; Toyoda, Asami; Koshida, Haruka; Sakuta, Keita; Takata, Tadanori; Koshida, Kichiro; Iida, Hiroji; Matsui, Osamu

2012-01-01

Recently, specific computed tomography (CT) scanners have been equipped with organ‐based tube current modulation (TCM) technology. It is possible that organ‐based TCM will replace the conventional dose‐reduction technique of reducing the effective milliampere‐second. The aim of this study was to determine if organ‐based TCM could reduce radiation exposure to the breasts without compromising the image uniformity and beam hardening effect in thoracic CT examinations. Breast and skin radiation doses and the absorbed radiation dose distribution within a single section were measured with an anthropomorphic phantom and radiophotoluminescent glass dosimeters using four approaches to thoracic CT (reference, organ‐based TCM, copper shielding, and the combination of the above two techniques, hereafter referred to as the combination technique). The CT value and noise level were measured using the same calibration phantom. Organ‐based TCM and copper shielding reduced radiation doses to the breast by 23.7% and 21.8%, respectively. However, the CT value increased, especially in the anterior region, using copper shielding. In contrast, the CT value and noise level barely increased using organ‐based TCM. The combination technique reduced the radiation dose to the breast by 38.2%, but greatly increased the absorbed radiation dose from the central to the posterior regions. Moreover, the CT value increased in the anterior region and the noise level increased by more than 10% in the entire region. Therefore, organ‐based TCM can reduce radiation doses to breasts with only small increases in noise levels, making it preferable for specific groups of patients, such as children and young women. PACS numbers: 87.53.Bn; 87.57.Q‐; 87.57.qp PMID:22402390

Review of damages of nuclear power plants steam generator's tubes and way of detecting by using eddy current method

International Nuclear Information System (INIS)

Stanic, D.

1996-01-01

Steam generator tubing integrity is very important factor for reliable and safe operation of NPP. Several different types of tube degradation mechanisms were experienced in SG operation. To avoid possible tube rupture and primary-to-secondary leak, the EC examination of tubing should be performed. Different eddy current techniques may be used for detecting defects and theirs characterization. A comparison of data analysis results with pulled tube destructive metallography results can provide valuable insights in determining the capability of existing technology and provide guidance for procedure or technology improvements. (author)

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.

Falling film evaporation on a tube bundle with plain and enhanced tubes

International Nuclear Information System (INIS)

Habert, M.

2009-04-01

The complexities of two-phase flow and evaporation on a tube bundle present important problems in the design of heat exchangers and the understanding of the physical phenomena taking place. The development of structured surfaces to enhance boiling heat transfer and thus reduce the size of evaporators adds another level of complexity to the modeling of such heat exchangers. Horizontal falling film evaporators have the potential to be widely used in large refrigeration systems and heat pumps, in the petrochemical industry and for sea water desalination units, but there is a need to improve the understanding of falling film evaporation mechanisms to provide accurate thermal design methods. The characterization of the effect of enhanced surfaces on the boiling phenomena occurring in falling film evaporators is thus expected to increase and optimize the performance of a tube bundle. In this work, the existing LTCM falling film facility was modified and instrumented to perform falling film evaporation measurements on single tube row and a small tube bundle. Four types of tubes were tested including: a plain tube, an enhanced condensing tube (Gewa-C+LW) and two enhanced boiling tubes (Turbo-EDE2 and Gewa-B4) to extend the existing database. The current investigation includes results for two refrigerants, R134a and R236fa, at a saturation temperature of T sat = 5 °C, liquid film Reynolds numbers ranging from 0 to 3000, at heat fluxes between 20 and 60 kW/m² in pool boiling and falling film configurations. Measurements of the local heat transfer coefficient were obtained and utilized to improve the current prediction methods. Finally, the understanding of the physical phenomena governing the falling film evaporation of liquid refrigerants has been improved. Furthermore, a method for predicting the onset of dry patch formation has been developed and a local heat transfer prediction method for falling film evaporation based on a large experimental database has been proposed

Optimization of recommendations for abdomen computerized tomography based on reconstruction filters, voltage and tube current

International Nuclear Information System (INIS)

Silveira, Vinicius da Costa

2015-01-01

The use of computed tomography has increased significantly over the past decades. In Brazil the use increased more than twofold from 2008 to 2014, in the meantime the abdomen procedures have tripled. The high frequency of this procedure combined by the increasing collective radiation dose in medical exposures, has resulted development tools to maximize the benefit in CT images. This work aimed to establish protocols optimized in abdominal CT through acquisitions parameters and reconstructions techniques based on filters kernels. A sample of patients undergoing abdominal CT in a diagnostic center of Rio de Janeiro was assessed. Had been collected patients information and acquisitions parameters. The phantoms CT image acquisitions were performed by using different voltage values by adjusting the tube current (mAs) to obtain the same value from CTDI vol patients with normal BMI. Afterwards, the CTDIvol values were reduced by 30%, 50% and 60%. All images were reconstructed with low-contrast filters (A) and standard filters (B). The CTDIvol values for patients with normal BMI were 7% higher than in patients with underweight BMI and 30%, 50% and 60% lower than the overweight, obese I and III patients, respectively. The evaluations of image quality showed that variation of the current (mA) and the reconstruction filters did not affect the Hounsfield values. When the contrast-to-noise ratio (CNR) was normalized to CTDIvol, the protocols acquired with 60% reduction of CTDIvol with 140 kV and 80 kV showed CNR 6% lower than the routine. Modifications of the acquisition parameters did not affect spatial resolution, but the post-processing with B filters reduced the spatial frequency by 16%. With reduced the dose of 30%, lesions in the spleen had the CNR higher than 10% routine protocols with 140 kV acquired and post-processed to filter A. The image post-processing with a filter A with a 80kV voltage provided CNR values equal to the routine for the liver lesions with a 30

Removing Eddy-current probe wobble noise from steam generator tubes testing using wavelet transform

International Nuclear Information System (INIS)

Lopez, Luiz Antonio Negro Martin; Ting, Daniel Kao Sun; Upadhyaya, Belle R.

2005-01-01

One of the most import nondestructive evaluation (NDE) applied to steam generator tubes inspection is the electromagnetic Eddy-Current testing (ECT). The signals generated in this NDE, in general, contain many noises which make difficult the interpretation and analysis of ECT signals. One of the noises present in the signals is the probe wobble noise, which is caused by the existing slack between the probe and the tube. In this work, Wavelet Transform (WT) is used in the probe wobble de-noising. WT is a relatively recent mathematical tool, which allows local analysis of non stationary signals such as ECT signals. This is a great advantage of WT when compared with other analysis tools such as Fourier Transform. However, using WT involves wavelets and coefficients selection as well as choosing the number of decomposition level needed. This work presents a probe wobble de-noising method when used in conjunction with the traditional ECT evaluation. Comparative results using several WT applied do Eddy-Current signals are presented in a reliable way, in other words, without loss of inherent defect information. A stainless steel tube, with 2 artificial defects generated by electro-erosion, was inspected by a ZETEC MIZ-17ET ECT equipment. The signals were de-noised through several different WT and the results are presented. The method offer good results and is a promising method because allows for the removal of Eddy-Current signals probe wobble effect without loss of essential signal information. (author)

The effect of angular and longitudinal tube current modulations on the estimation of organ and effective doses in x-ray computed tomography

International Nuclear Information System (INIS)

Straten, Marcel van; Deak, Paul; Shrimpton, Paul C.; Kalender, Willi A.

2009-01-01

Purpose: Tube current modulation (TCM) is one of the recent developments in multislice CT that has proven to reduce the patient radiation dose without affecting the image quality. Presently established methods and published coefficients for estimating organ doses from the dose measured free in air on the axis of rotation or in the CT dose index (CTDI) dosimetry phantoms do not take into account this relatively new development in CT scanner design and technology. Based on these organ dose coefficients effective dose estimates can be made. The estimates are not strictly valid for CT scanning protocols utilizing TCM. In this study, the authors investigated the need to take TCM into account when estimating organ and effective dose values. Methods: A whole-body adult anthropomorphic phantom (Alderson Rando) was scanned with a multislice CT scanner (Somatom Definition, Siemens, Forchheim, Germany) utilizing TCM (CareDose4D). Tube voltage was 120 kV, beam collimation 19.2 mm, and pitch 1. A voxelized patient model was used to define the tissues and organs in the phantom. Tube current values as a function of tube angle were obtained from the raw data for each individual tube rotation of the scan. These values were used together with the Monte Carlo dosimetry tool IMPACTMC (VAMP GmbH, Erlangen, Germany) to calculate organ dose values both with and without account of TCM. Angular and longitudinal modulations were investigated separately. Finally, corresponding effective dose conversion coefficients were determined for both cases according to the updated 2007 recommendations of the ICRP. Results: TCM amplitude was greatest in the shoulder and pelvic regions. Consequently, dose distributions and organ dose values for particular cross sections changed considerably when taking angular modulation into account. The effective dose conversion coefficients were up to 11% lower for a single rotation in the shoulder region and 17% lower in the pelvis when taking angular TCM into

Low-dose respiratory-gated PET/CT: based on 30 mA tube current

International Nuclear Information System (INIS)

Wu Ping; Li Sijin; Zhang Yanlan; Hao Xinzhong; Qin Zhixing; Yan Min; Cheng Pengliang; Wu Zhifang

2013-01-01

Objective: To establish a low-dose but image-comparable respiratory-gated PET/CT (RG PET/CT) protocol based on 30 mA tube current plus other improved scanning parameters, such as the tube current, the number of respiratory phase and length of breathing cycle. Methods: Twenty-six patients with 18 F-FDG-intaking lung nodules underwent one-bed standard-dose PET/CT (120 mA, 2 min/bed) and low dose RG PET/CT (30 mA, 6 respiratory phases, 1 min/phase). The radiation dose and image quality were analyzed subsequently with signal to noise ratio (SNR) for PET and the homogeneity, noise level for CT in the water phantom respectively. Otherwise the CT images were both visual evaluated by two experienced doctors. In addition, different respiratory cycle was simulated to observe its relation with radiation dose. Results: The effective dose of low-dose RG PET/CT was 4.88∼7.69 mSv [mean (5.68±0.83) mSv]. The PET SNR showed no significance between groups. The homogeneity of 30 mA is good (< 5 HU), although noise level was high, the visual character like lobulation, speculation of lung nodule was superior in some respiratory phases. The radiation dose was positively correlated with respiratory cycle. Conclusions: The performance of low-dose RG PET/CT was comparable to those of standard-dose PET/CT based on a protocol with 30 mA tube current, 6 respiratory phases and breathing state of eupnoea. It produced a much lower radiation exposure and the image quality was enough for clinical use such as delineation of tumor active target, characterization and staging of lung nodules, etc. (authors)

Particular treatments in Eddy current technique. Application to the control of corrugated tubes

International Nuclear Information System (INIS)

1982-11-01

When the testing of a given product shows that, owing to a particular shape of this product or to its environment, disturbing effects can hide the presence of harmful defects, use must be made of testing artifices or particular treatments enabling an efficient examination to be made. On this score, many eddy current problems are solved by means of the following processes: - use of specific sensors adapted to the geometry of the product, - spectral analysis of the analog results of analyses, - combination of the results of analyses obtained simultaneously at different frequencies (multifrequency techniques). An example of an application is given for corrugated tubes achieved by hollow and helical milling of smooth tubes [fr

Gastroenteric tube feeding: Techniques, problems and solutions

Science.gov (United States)

Blumenstein, Irina; Shastri, Yogesh M; Stein, Jürgen

2014-01-01

Gastroenteric tube feeding plays a major role in the management of patients with poor voluntary intake, chronic neurological or mechanical dysphagia or gut dysfunction, and patients who are critically ill. However, despite the benefits and widespread use of enteral tube feeding, some patients experience complications. This review aims to discuss and compare current knowledge regarding the clinical application of enteral tube feeding, together with associated complications and special aspects. We conducted an extensive literature search on PubMed, Embase and Medline using index terms relating to enteral access, enteral feeding/nutrition, tube feeding, percutaneous endoscopic gastrostomy/jejunostomy, endoscopic nasoenteric tube, nasogastric tube, and refeeding syndrome. The literature showed common routes of enteral access to include nasoenteral tube, gastrostomy and jejunostomy, while complications fall into four major categories: mechanical, e.g., tube blockage or removal; gastrointestinal, e.g., diarrhea; infectious e.g., aspiration pneumonia, tube site infection; and metabolic, e.g., refeeding syndrome, hyperglycemia. Although the type and frequency of complications arising from tube feeding vary considerably according to the chosen access route, gastrointestinal complications are without doubt the most common. Complications associated with enteral tube feeding can be reduced by careful observance of guidelines, including those related to food composition, administration rate, portion size, food temperature and patient supervision. PMID:25024606

The counter-current flooding limit in vertical tubes with and without orifices

International Nuclear Information System (INIS)

Tye, P.; Davidson, M.; Teyssedou, A.; Tapucu, A.; Matuszkiewicz, A.; Midvidy, W.

1993-01-01

For hypothetical loss of coolant accidents in nuclear reactors, rapid reflooding of the core is desirable. In CANDU reactors the cooling water is injected into the headers which are connected to the fuel channels by the feeder pipes. These pipes consist of vertical and horizontal runs; in some feeders, orifices and/or venturi flow meters are installed for flow adjustments and measurements respectively. For certain postulated accident scenarios, steam coming from the fuel channels and/or generated in the hot feeders may flow in the direction opposite to that of the cooling water thereby, creating a vertical or horizontal counter-current two-phase flow. Under these conditions, the rate at which cooling water can enter the fuel channels may be limited by the flooding phenomena. This phenomena is greatly affected by the geometry of the feeder pips, shape and number of fittings, and the flow area restrictions located in the feeders. In this paper the influence that orifice type flow area restrictions have on the counter-current flooding limit (CCFL) in a vertical tube is examined. air and water at close to atmospheric conditions are used as the working fluids. The data collected on the counter-current flooding limit in a vertical tube both with and without flow area restrictions is compared against some of the most commonly used correlations that are available in the open literature. Data on the two-phase counter-current pressure drop below the flooding point are also presented. 12 refs., 10 figs., 1 tab

Eddy-current testing of nuclear fuel cladding tubes using tilted encircling coil system, 1

International Nuclear Information System (INIS)

Yin, Renzhong; Sekine, Kazuyoshi; Shimizu, Hisaji; Tsukui, Kazushige; Urata, Megumu.

1989-01-01

The eddy current testing method with external encircling-coils has been widely used as a standard technique for inspection of defects in irradiated zircaloy cladding tubes. In this inspection, the systematic procedure to reliably characterize defects is required. This paper describes the newly developed external tilted encircling-coil system, in which the coil axis is inclined by an angle α to the sample tube axis, for reliable determination of the sort, location and size of defects. As the results of experimental work concerning some kinds of artificial defects in zircaloy cladding tubes using newly designed tilted coil system, an adaptable general-procedure for characterization of defects has been proposed. Furthermore, it has been confirmed that in the case of smaller tilt angles of coil, the signal-to noise ratio for defect response in this coil system is approximately equal to that of ordinary encircling coil system. (author)

Iterative reconstruction for quantitative computed tomography analysis of emphysema: consistent results using different tube currents

Directory of Open Access Journals (Sweden)

Yamashiro T

2015-02-01

Full Text Available Tsuneo Yamashiro,1 Tetsuhiro Miyara,1 Osamu Honda,2 Noriyuki Tomiyama,2 Yoshiharu Ohno,3 Satoshi Noma,4 Sadayuki Murayama1 On behalf of the ACTIve Study Group 1Department of Radiology, Graduate School of Medical Science, University of the Ryukyus, Nishihara, Okinawa, Japan; 2Department of Radiology, Osaka University Graduate School of Medicine, Suita, Osaka, Japan; 3Department of Radiology, Kobe University Graduate School of Medicine, Kobe, Hyogo, Japan; 4Department of Radiology, Tenri Hospital, Tenri, Nara, Japan Purpose: To assess the advantages of iterative reconstruction for quantitative computed tomography (CT analysis of pulmonary emphysema. Materials and methods: Twenty-two patients with pulmonary emphysema underwent chest CT imaging using identical scanners with three different tube currents: 240, 120, and 60 mA. Scan data were converted to CT images using Adaptive Iterative Dose Reduction using Three Dimensional Processing (AIDR3D and a conventional filtered-back projection mode. Thus, six scans with and without AIDR3D were generated per patient. All other scanning and reconstruction settings were fixed. The percent low attenuation area (LAA%; < -950 Hounsfield units and the lung density 15th percentile were automatically measured using a commercial workstation. Comparisons of LAA% and 15th percentile results between scans with and without using AIDR3D were made by Wilcoxon signed-rank tests. Associations between body weight and measurement errors among these scans were evaluated by Spearman rank correlation analysis. Results: Overall, scan series without AIDR3D had higher LAA% and lower 15th percentile values than those with AIDR3D at each tube current (P<0.0001. For scan series without AIDR3D, lower tube currents resulted in higher LAA% values and lower 15th percentiles. The extent of emphysema was significantly different between each pair among scans when not using AIDR3D (LAA%, P<0.0001; 15th percentile, P<0.01, but was not

Method and system for a gas tube switch-based voltage source high voltage direct current transmission system

Science.gov (United States)

She, Xu; Chokhawala, Rahul Shantilal; Zhou, Rui; Zhang, Di; Sommerer, Timothy John; Bray, James William

2016-12-13

A voltage source converter based high-voltage direct-current (HVDC) transmission system includes a voltage source converter (VSC)-based power converter channel. The VSC-based power converter channel includes an AC-DC converter and a DC-AC inverter electrically coupled to the AC-DC converter. The AC-DC converter and a DC-AC inverter include at least one gas tube switching device coupled in electrical anti-parallel with a respective gas tube diode. The VSC-based power converter channel includes a commutating circuit communicatively coupled to one or more of the at least one gas tube switching devices. The commutating circuit is configured to "switch on" a respective one of the one or more gas tube switching devices during a first portion of an operational cycle and "switch off" the respective one of the one or more gas tube switching devices during a second portion of the operational cycle.

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

International Nuclear Information System (INIS)

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

2014-01-01

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

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.

Helical CT for lung-cancer screening. 3. Fundamental study for ultra-low-dose CT by application of small tube current and filter

International Nuclear Information System (INIS)

Itoh, Shigeki; Koyama, Shuji; Tusaka, Masatoshi; Maekoshi, Hisashi; Satake, Hiroko; Ishigaki, Takeo.

1996-01-01

In order to develop ultra-low-dose helical CT for lung cancer screening, the effect of reduction of the tube current to 20 mA and application of a 10 mm thick aluminium filter upon radiation dose and image quality was evaluated with a phantom. Exposure dose at the center of a gantry and absorbed dose at the center of an acrylic phantom at 20 mA with the filter were 15% and 29% of the dose at 50 mA without the filter, respectively. For reduction of absorbed dose, reduction of the tube current was more useful than application of the filter. Image noise at 20 mA with the filter was double that at 50 mA without the filter. Neither reduction of the tube current nor application of the filter changed full width at half maximum on section sensitivity of the Z-axis. Although reduction of the tube current did not affect the difference in CT values between an acrylic sphere and styroform, application of the filter caused a reduction of 4.5% in the difference in CT values. Neither reduction of the tube current nor application of the filter affected the contrast resolution of the high-contrast phantom; however, that of the low-contrast phantom deteriorated. Although improvement of the filter and evaluation of clinical images are necessary, reduction of the tube current to 20 mA and application of the aluminium filter appear to be a promising method for ultra-low-dose helical CT of the lung. (author)

Reducing Current Spread using Current Focusing in Cochlear Implant Users

Science.gov (United States)

Landsberger, David M.; Padilla, Monica; Srinivasan, Arthi G.

2012-01-01

Cochlear implant performance in difficult listening situations is limited by channel interactions. It is known that partial tripolar (PTP) stimulation reduces the spread of excitation (SOE). However, the greater the degree of current focusing, the greater the absolute current required to maintain a fixed loudness. As current increases, so does SOE. In experiment 1, the SOE for equally loud stimuli with different degrees of current focusing is measured via a forward-masking procedure. Results suggest that at a fixed loudness, some but not all patients have a reduced SOE with PTP stimulation. Therefore, it seems likely that a PTP speech processing strategy could improve spectral resolution for only those patients with a reduced SOE. In experiment 2, the ability to discriminate different levels of current focusing was measured. In experiment 3, patients subjectively scaled verbal descriptors of stimuli of various levels of current focusing. Both discrimination and scaling of verbal descriptors correlated well with SOE reduction, suggesting that either technique have the potential to be used clinically to quickly predict which patients would receive benefit from a current focusing strategy. PMID:22230370

Feasibility study of automatic tube current modulation in low-dose thoracic imaging for young children with 64-slice spiral CT

International Nuclear Information System (INIS)

Peng Yun; Li Jianyin; Zhang Qifeng; Liu Yue; Wang Bei; Zheng Jinjin

2008-01-01

Objective: To assess the feasibility of using an automatic tube current modulation (ATCM) method to obtain consistent image quality with reduced radiation dose for young children undergoing chest scans with a set of 64-slice spiral CT. Methods: Fifty young children underwent chest scans on a GE 64-slice VCT with automatic tube current modulation. The noise index (NI) for this study group was set to 8 or 9 based on the proposed reference for pediatric chest imaging in our hospital. We compared image quality and radiation dose for the study group with the age-matched control group of 50 young children acquired with standard protocol of fixed-mAs (120 and 150 mAs for under 1 and above 1 year old, respectively). The volume CT dose index(CTDIvol) values were recorded for both groups. Two experienced pediatric radiologists assessed image quality on a 5-point scale with 5 being the best. Scores greater than or equal to 3 were considered clinically acceptable. The degree of interobserver concordance was determined by Kappa statistics. Results: The average objective image noise and CTDIvol for control group was (4.78±0.58) and (6.68±0.62) mGy, respectively. For the study group the mean value of objective mAs was (41.6±11.6) (20-79 mAs) with mean CTDIvol of (2.34±0.71) mGy, and the use of ATCM produced mean noise of (7.84±0.66). The average CTDIvol with the use of NI of 8-9 was about 65% lower than that with the fixed mAs setting. The mean image quality score for the study group and control group was (3.46±0.40) and (4.65±0.46) respectively. All studies had acceptable image quality, and there was good inter-observer agreement in diagnostic acceptability (Kappa=0.474 and 0.536). Conclusion: The automatic tube current modulation method could be used to obtain consistent image quality for young children undergoing 64-slice MSCT chest scans. With proper noise level setting (NI=8 or 9), one may obtain clinically acceptable images with much reduced radiation dose. (authors)

MO-F-CAMPUS-I-04: Patient Eye-Lens Dose Reduction in Routine Brain CT Examinations Using Organ-Based Tube Current Modulation and In-Plane Bismuth Shielding

International Nuclear Information System (INIS)

Tsai, Hui-Yu; Liao, Ying-Lan; Lai, Nan-Ku; Chen, Tou-Rong; Chen, Jun-Rong

2015-01-01

Purpose: The purpose of this study is to assess eye-lens dose for patients who underwent brain CT examinations using two dose reduction Methods: organ-based tube current modulation (OBTCM) and in-plane bismuth shielding method. Methods: This study received institutional review board approval; written informed consent to participate was obtained from all patients. Ninety patients who underwent the routine brain CT examination were randomly assigned to three groups, ie. routine, OBTCM, and bismuth shield. The OBTCM technique reduced the tube current when the X-ray tube rotates in front of patients’ eye-lens region. The patients in the bismuth shield group were covered one-ply bismuth shield in the eyes’ region. Eye-lens doses were measured using TLD-100H chips and the total effective doses were calculated using CT-Expo according to the CT scanning parameters. The surface doses for patients at off-center positions were assessed to evaluate the off-centering effect. Results: Phantom measurements indicates that OBTCM technique could reduced by 26% to 28% of the surface dose to the eye lens, and increased by 25% of the surface dose at the opposed incident direction at the angle of 180°. Patients’ eye-lens doses were reduced 16.9% and 30.5% dose of bismuth shield scan and OBTCM scan, respectively compared to the routine scan. The eye-lens doses were apparently increased when the table position was lower than isocenter. Conclusion: Reducing the dose to the radiosensitive organs, such as eye lens, during routine brain CT examinations could lower the radiation risks. The OBTCM technique and in-plane bismuth shielding could be used to reduce the eye-lens dose. The eye-lens dose could be effectively reduced using OBTCM scan without interfering the diagnostic image quality. Patient position relative the CT gantry also affects the dose level of the eye lens. This study was supported by the grants from the Ministry of Science and Technology of Taiwan (MOST103-2314-B-182

Eddy current inspection of tubing; Inspeccion de tubos por corrientes de Foucault

Energy Technology Data Exchange (ETDEWEB)

Bauza, J L. R.; Herrero, J; Diaz, J

1966-07-01

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

Establishment of a semi-biological phantom model for the study of the effect of dose reducing measures on radiation-induced DNA double strand breaks in CT using the example of risk organ based tube current modulation; Etablierung eines semibiologischen Phantommodells zur Untersuchung des Effekts dosisreduzierender Massnahmen auf strahleninduzierte DNA-Doppelstrangbrueche in der CT am Beispiel der risikoorganbasierten Roehrenstrommodulation

Energy Technology Data Exchange (ETDEWEB)

Sommer, Matthias

2013-12-12

The number of computed tomography (CT) examinations has been rising during the last decades. Therefore techniques for dose reduction receive increasing attention. Risk organ-based tube current modulation (RCM) in CT is a new approach and works by lowering the tube current, while the tube is in front of the patient's body. Therefore it should lead to a dose reduction for radiosensitive organs like the female breast, the eye lenses and the thyroid gland. Biological radiation effects cannot be estimated by physical-based dose measurements. γ-H2AX is a sensitive marker for the determination of x-ray induced DNA double-strand breaks (DSB). Hence the aim of this study was to establish a biological phantom model based on the γ-H2AX immunofluorescence microscopy method and to investigate the effect of RCM on radiation induced DNA damages. The γ-H2AX method is based on the phosphorylation of the histone variant H2AX. The phosphorylated histone γ-H2AX can be visualised using antibodies and is specific for radiation induced DSB. Blood lymphocytes from healthy volunteers, skin fibroblasts (LN) and mammary epithelial cells (HMEpC-p) were placed in different positions of an Alderson-phantom and exposed to x-rays using a 128-slice dual-source CT scanner. Standard head, neck and chest-CT scan protocols either with or without risk-organ based tube current modulation were used. RCM reduces the tube current to 20 percent at an angle of 130 degree anterior to the body, whereas tube current is increased at an angle of 230 degree posterior to the body. Afterwards cells were isolated, fixed on slides und stained with specific primary γ-H2AX antibodies and fluorescent secondary antibodies. Tiny green dots (named foci) can be detected and quantified with a fluorescence microscope and represent distinct DSB. Non-irradiated samples served as controls and CT-induced DSB were calculated by subtraction of pre- from post-exposure values. In this study a semibiological phantom model

Application of eddy currents for identification of dimensional variations in PWR steam generator tubes and detection of stress corrosion cracks

International Nuclear Information System (INIS)

Comby, R.; Gourmelon, A.

1985-01-01

To avoid the risk of cracking on the secondary side of the roll expansion transition zone in steam generator (SG) tubes, tube profile at the upper face of the tube sheet must comply with specifications laid down by the manufacturer and EDF. EDF has developed an eddy current (EC) signal identification method, used for pre-service testing to detect any deviation in tube profile. Nevertheless, circumferential or longitudinal stress corrosion cracks (SCC), initiated on the primary side, have appeared on some SGs. A special rotating probe was used on these generators. The results of these checks have been correlated with metallurgical examination of the extracted tubes

Heat Exchanger Tube to Tube Sheet Joints Corrosion Behavior

Directory of Open Access Journals (Sweden)

M. Iancu

2013-03-01

Full Text Available Paper presents the studies made by the authors above the tube to tube sheet fittings of heat exchanger with fixed covers from hydrofining oil reforming unit. Tube fittings are critical zones for heat exchangers failures. On a device made from material tube and tube sheet at real joints dimensions were establish axial compression force and traction force at which tube is extracted from expanded joint. Were used two shapes joints with two types of fittings surfaces, one with smooth hole of tube sheet and other in which on boring surface we made a groove. From extracted expanded tube zones were made samples for corrosion tests in order to establish the corrosion rate, corrosion potential and corrosion current in working mediums such as hydrofining oil and industrial water at different temperatures. The corrosion rate values and the temperature influence are important to evaluate joints durability and also the results obtained shows that the boring tube sheet shape with a groove on hole tube shape presents a better corrosion behavior then the shape with smooth hole tube sheet.

Computer modelling of eddy current probes for ISI of pressure tube/calandria tube assemblies in PHWRs

International Nuclear Information System (INIS)

Rao, B.P.C.; Shyamsunder, M.T.; Bhattacharya, D.K.; Raj, Baldev

1992-01-01

Non-destructive Evaluation (NDE) plays a major role in ensuring the safe and reliable operation of PHWRs which are the mainstay of India's nuclear power programme. An important in-service inspection (ISI) requirement in these reactors is carried out through Eddy Current Testing (ECT) of the pressure tube (PT)/calandria tube (CT) assemblies. The material of construction of these assemblies is zircaloy-2. The two main objectives of this ISI are the detection of garter spring between CT and PT and the profiling of gap between CT and PT. The paper discusses the work carried out at the authors' laboratory on the development of ECT probes for ISI of PT/CT assemblies. Emphasis has been given on the work done on the design and optimisation of the probes using computer modeling. A 2-D finite element code has been developed for this purpose. The code is developed around a diffusion equation which can be derived from Maxwell's equations governing the electromagnetic phenomenon. An axisymmetry has been considered, since the probes are bobbin type. Results of impedance plane outputs obtained by modelling and those by experiments using actual probes have shown good matching. Salient features of an indigenously developed interactive PC based data acquisition, analysis and retrieval system to cater to ISI of PC/CT assemblies are described. (author). 10 refs., 7 figs

Dose reduction in multi-slice CT of the heart by use of ECG-controlled tube current modulation (''ECG pulsing''): phantom measurements

International Nuclear Information System (INIS)

Poll, L.W.; Cohnen, M.; Brachten, S.; Moedder, U.; Ewen, K.

2002-01-01

To evaluate the effect of ECG-controlled tube current modulation on radiation exposure in retrospectively-ECG-gated multislice CT (MSCT) of the heart. Material and methods: Three different cardiac MSCT protocols with different slice collimation (4 x 1, and 4 x 2.5 mm), and a pitch-factor of 1.5 and 1.8 were investigated at a multi-slice CT scanner Somatom Volume Zoom, Siemens. An anthropomorphic Alderson-Rando phantom was equipped with LiF-Thermoluminescence dosimeters at several organ sites, and effective doses were calculated using ICRP-weighting factors. Scan protocols were performed with ECG-controlled tube current modulation ('ECG pulsing') at two different heart rates (60 and 80 bpm). These data were compared to previous data from MSCT of the heart without use of 'ECG pulsing'. Results: Radiation exposure with (60 bpm) and without tube current modulation using a 2.5 mm collimation was 1.8 mSv and 2.9 mSv for females, and 1.5 mSv and 2.4 mSv for males, respectively. For protocols using a 1 mm collimation with a pitch-factor of 1.5 (1.8), radiation exposure with and without tube current modulation was 5.6 (6.3) mSv and 9.5 (11.2) mSv for females, and 4.6 (5.2) mSv and 7.7 (9.2) mSv for males, respectively. At higher heart rates (80 bpm) radiation exposure is increased from 1.5-1.8 mSv to 1.8-2.1 mSv, using the 2.5 mm collimation, and from 4.6-5.6 mSv to 5.9-7.2 mSv, for protocols using 1 mm collimation. Conclusions: The ECG-controlled tube current modulation allows a dose reduction of 37% to 44% when retrospectively ECG-gated MSCT of the heart is performed. The tube current - as a function over time - and therefore the radiation exposure is dependent on the heart rate. (orig.) [de

Oral care may reduce pneumonia in the tube-fed elderly: a preliminary study.

Science.gov (United States)

Maeda, Keisuke; Akagi, Junji

2014-10-01

Pneumonia is one of the most important diseases in terms of mortality in the elderly. In particular, bedridden patients who are forbidden oral ingestion during enteral nutrition may have a poor outcome resulting from a respiratory infection. Oral hygiene can play a positive role in preventing aspiration pneumonia in the elderly. The aim of this study was to investigate the effectiveness of oral hygiene for bedridden and tube-fed patients at an increased risk of pneumonia. This retrospective study was conducted from July 2011 to June 2013 on a long-term-care hospital unit. The oral care protocol (OCP) intervention commenced in July 2012, during the study period. The subjects of this study were 63 elderly patients with a mean age of 81.7 years. Thirty-one patients were enrolled in the OCP intervention group, and the mean observation length was 130.4 days; the mean observation length for the 32 patients in the control group was 128.4 days. The incidence of pneumonia and the numbers of days with a recorded fever, antibiotics administration, blood tests, and radiological examinations were reduced from 1.20 to 0.45, 24.57 to 17.48, 25.52 to 10.12, 10.91 to 6.54, and 6.33 to 3.09 %, respectively. These reductions were significantly less in the OCP intervention group. In conclusion, the results of the present study suggest that daily oral care for tube-fed patients who do not receive nutrition by mouth reduced the incidence of pneumonia. In addition to patients consuming food by mouth, all tube-fed patients require dedicated oral care to maintain healthy oral conditions.

Inspection and repair of steam generator tubing with a robot

International Nuclear Information System (INIS)

Boehm, H.H.; Foerch, H.

1985-01-01

During inspection and repair of steam generator tubing, radiation exposure to personnel is an unrequested endowment. To combat this intrinsic handicap, a robot has been designed for deployment in all operations inside the steam generator water chamber. This measure drastically reduces entering time and also improves inspection capabilities with regard to the accuracy and reproduction of the desired tube address. The inherent flexibility of the robot allows for performing various inspection and repair techniques: eddy-current testing of tubing; ultrasonic testing of tubing; visual examination of tube ends; profilometry measurements; tube plugging; plug removal; tube extraction; sleeving of tubes; tube end repair; chemical cleaning; and thermal treatment. Plant experience has highlighted the following features of the robot: 1) short installation and demounting periods; 2) installation independent of manhole location; 3) installation possible from outside the steam generator; 4) only one relocation required to address all the tube positions; 5) fast and highly accurate positioning; 6) operational surveillance not required; and 7) drastic reduction of radiation exposure to personnel during repair work

NEI You Tube Videos: Amblyopia

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An overview of current developments in position-sensitive hybrid photon detectors and photo-multiplier tubes

CERN Document Server

Gys, Thierry

1999-01-01

Current developments in position-sensitive hybrid photon detectors and photo-multiplier tubes have stimulated increased interest from a variety of fields such as astronomy, biomedical imaging and high- energy physics. These devices are sensitive to single photons over a photon energy spectrum defined by the transmission of the optical entrance window and the photo-cathode type. Their spatial resolution ranges from a few millimeters for pad hybrid photon detectors and multi-anode photo-multiplier tubes down to a few tens of microns for pixel hybrid photon detectors and electron-bombarded charge-coupled devices. Basic technological and design aspects are assessed in this paper. (21 refs).

Methods of evaluation of accuracy with multiple essential parameters for eddy current measurement of pressure tube to calandria tube gap in CANDU reactors

Energy Technology Data Exchange (ETDEWEB)

Shokralla, S., E-mail: shaddy.shokralla@opg.com [Ontario Power Generation, IMS NDE Projects, Ajax, Ontario (Canada); Krause, T.W., E-mail: thomas.krause@rmc.ca [Royal Military College of Canada, Kingston, Ontario (Canada)

2014-01-15

The purpose of inspection qualification of a particular inspection system is to show that it meets applicable inspection specification requirements. Often a requirement of the inspection system is that it meets a particular accuracy. In the case of a system with multiple inputs accompanied by additional influential parameters, calculation of the system's output accuracy can be formidable. Measurement of pressure-tube to calandria tube gap in CANDU reactors using an eddy current based technique is presented as a particular example of a system where multiple essential parameters combine to generate a final uncertainty for the inspection system. This paper outlines two possible methods of calculating such a system's accuracy, and discusses the advantages and disadvantages of each. (author)

NEI You Tube Videos: Amblyopia

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Full Text Available ... search for current job openings visit HHS USAJobs Home » NEI YouTube Videos » NEI YouTube Videos: Amblyopia Listen NEI YouTube Videos YouTube Videos Home Age-Related Macular Degeneration Amblyopia Animations Blindness Cataract ...

Low volume tubes are not effective to reduce the rate of hemolyzed specimens from the emergency department.

Science.gov (United States)

Lippi, Giuseppe; Bonelli, Patrizia; Graiani, Virna; Caleffi, Catia; Cervellin, Gianfranco

2014-02-01

Spurious hemolysis is the leading source of nonconformities that can be recorded in diagnostic samples, especially those collected in the emergency department (ED). The aim of this study was to assess whether the shift from regular to low volume blood collection tubes may reduce the rate of hemolysis in a large urban ED, where approximately 80% of blood collections are performed through catheters. In a former 5-month period, blood collection in the ED was performed using 5.0mL (13×100mm) plastic serum tubes, which were then completely replaced with 3.5mL (13×75mm) plastic serum tubes for another period of 5months. The rate of hemolyzed specimens (i.e., those containing a cell-free hemoglobin ≥0.5gL) collected in the two periods was compared by Fisher exact test. The rate of hemolyzed specimens received from the ED increased from 3.5% using 5.0mL plastic serum tubes to 5.2% after introduction of 3.5mL plastic serum tubes (p<0.001). The use of low volume tubes was not effective to decrease the hemolysis rate in a large urban ED. Copyright © 2013 The Canadian Society of Clinical Chemists. Published by Elsevier Inc. All rights reserved.

SU-F-207-03: Dosimetric Effect of the Position of Arms in Torso CT Scan with Tube Current Modulation

International Nuclear Information System (INIS)

Liu, H; Gao, Y; Xu, X; Zhuo, W; Wu, J

2015-01-01

Purpose: To evaluate the patient organ dose differences between the arms-raised and arms-lowered postures in Torso multidetector computed tomography (MDCT) scan protocols with tube current modulation (TCM). Methods: Patient CT organ doses were simulated using the Monte Carlo method with human phantoms and a validated CT scanner model. A set of adult human phantoms with arms raised and arms lowered postures were developed using advanced BREP-based mesh surface geometries. Organ doses from routine Torso scan protocols such as chest, abdomen-pelvis, and CAP scans were simulated. The organ doses differences caused by two different posutres were investigated when tube current modulation (TCM) were applied during the CT scan. Results: With TCM applied, organ doses of all the listed organs of arms-lowered posture phantom are larger than those of arms raised phantom. The dose difference for most of the organs or tissues are larger than 50%, and the skin doses difference for abdomen-pelvis scan even reaches 112.03%. This is due to the fact that the tube current for patient with arms-lowered is much higher than for the arms raised posture. Conclusion: Considering CT scan with TCM, which is commonly applied clinically, patients who could not raise their arms will receive higher radiation dose than the arms raised patient, with dose differences for some tissues such as the skin being larger than 100%. This is due to the additional tube current necessary to penetrate the arms while maintaining consistent image quality. National Nature Science Foundation of China(No.11475047)

Hypoglossal-Facial Nerve Reconstruction Using a Y-Tube-Conduit Reduces Aberrant Synkinetic Movements of the Orbicularis Oculi and Vibrissal Muscles in Rats

Directory of Open Access Journals (Sweden)

Yasemin Kaya

2014-01-01

Full Text Available The facial nerve is the most frequently damaged nerve in head and neck trauma. Patients undergoing facial nerve reconstruction often complain about disturbing abnormal synkinetic movements of the facial muscles (mass movements, synkinesis which are thought to result from misguided collateral branching of regenerating motor axons and reinnervation of inappropriate muscles. Here, we examined whether use of an aorta Y-tube conduit during reconstructive surgery after facial nerve injury reduces synkinesis of orbicularis oris (blink reflex and vibrissal (whisking musculature. The abdominal aorta plus its bifurcation was harvested (N = 12 for Y-tube conduits. Animal groups comprised intact animals (Group 1, those receiving hypoglossal-facial nerve end-to-end coaptation alone (HFA; Group 2, and those receiving hypoglossal-facial nerve reconstruction using a Y-tube (HFA-Y-tube, Group 3. Videotape motion analysis at 4 months showed that HFA-Y-tube group showed a reduced synkinesis of eyelid and whisker movements compared to HFA alone.

Hypoglossal-facial nerve reconstruction using a Y-tube-conduit reduces aberrant synkinetic movements of the orbicularis oculi and vibrissal muscles in rats.

Science.gov (United States)

Kaya, Yasemin; Ozsoy, Umut; Turhan, Murat; Angelov, Doychin N; Sarikcioglu, Levent

2014-01-01

The facial nerve is the most frequently damaged nerve in head and neck trauma. Patients undergoing facial nerve reconstruction often complain about disturbing abnormal synkinetic movements of the facial muscles (mass movements, synkinesis) which are thought to result from misguided collateral branching of regenerating motor axons and reinnervation of inappropriate muscles. Here, we examined whether use of an aorta Y-tube conduit during reconstructive surgery after facial nerve injury reduces synkinesis of orbicularis oris (blink reflex) and vibrissal (whisking) musculature. The abdominal aorta plus its bifurcation was harvested (N = 12) for Y-tube conduits. Animal groups comprised intact animals (Group 1), those receiving hypoglossal-facial nerve end-to-end coaptation alone (HFA; Group 2), and those receiving hypoglossal-facial nerve reconstruction using a Y-tube (HFA-Y-tube, Group 3). Videotape motion analysis at 4 months showed that HFA-Y-tube group showed a reduced synkinesis of eyelid and whisker movements compared to HFA alone.

Method for shaping polyethylene tubing

Science.gov (United States)

Kramer, R. C.

1981-01-01

Method forms polyethylene plastic tubing into configurations previously only possible with metal tubing. By using polyethylene in place of copper or stain less steel tubing inlow pressure systems, fabrication costs are significantly reduced. Polyethylene tubing can be used whenever low pressure tubing is needed in oil operations, aircraft and space applications, powerplants, and testing laboratories.

Special wrench for B-nuts reduces torque stress in tubing

Science.gov (United States)

Stein, J. A.

1970-01-01

Gear-driven torque wrench with bearing support is used to tighten B-nut connection of partially supported fluid line with minimum stress to adjacent tubing and fittings. Wrench is useful for working with weak or brittle lines such as glass tubing.

Final report on development evaluation of Task Group 3 pressure tubes

International Nuclear Information System (INIS)

Fleck, R.G.; Price, E.G.; Cheadle, B.A.

1983-11-01

This report describes the production and evaluation of pressure tubes manufactured to the recommendations of Task Group 3 (TG3) of the Creep Engineering Design Plan. The Zr-2.5 wt percent Nb tubes were manufactured by modified production route to change their metallurgical structure and so reduce the in-service elongation rates. Three modified routes were investigated and a total of twenty-eight tubes produced. There were no difficulties in manufacture and the tubes satisfied the quality assurance and design specifications of reactor grade tubes. Metallurgical evaluation showed that the expected changes in microstructure had occurred but not to the extent anticipated. The TG3 tubes were found to have comparable properties to current tubes when tested for: tensile strength (irradiated and unirradiated); hydride cracking; stress to reorient hydrides; hydrogen diffusion; flaw tolerance; corrosion (irradiated and unirradiated); wear; rolled joint characteristics; irradiation creep and growth. Lower in-service elongation rates are expected for tubes produced by two of the modified routes

Tube-support response to tube-denting evaluation. Volume 1. Final report

International Nuclear Information System (INIS)

Anderson, P.L.; Hall, J.F.; Shah, P.K.; Wills, R.L.

1983-05-01

The response of the tube supports is one of the important considerations of tube denting in a steam generator. Investigations have indicated that damaged tube supports have the potential to distort and damage tubes. This investigation considers the response to tube denting of the Combustion Engineering type tube supports. Drilled support plates and eggcrate tube supports are tested in a model steam generator in which tube denting is induced. The experimental data is used to verify and refine analytical predictor models developed using finite element techniques. It was found that analytical models underpredicted the deformations of the tube supports and appropriate modifications to enhance the predictive capability are identified. Non-destructive examination methods are evaluated for application to operating steam generators. It was found that the standard eddy current and profilometry techniques are acceptable methods for determining tube deformations, but these techniques are not adequate to assess tube support damage. Radiography is judged to be the best available means of determining the extent and progression of damage in tube supports

Tubing misconnections: normalization of deviance.

Science.gov (United States)

Simmons, Debora; Symes, Lene; Guenter, Peggi; Graves, Krisanne

2011-06-01

Accidental connection of an enteral system to an intravenous (IV) system frequently results in the death of the patient. Misconnections are commonly attributed to the presence of universal connectors found in the majority of patient care tubing systems. Universal connectors allow for tubing misconnections between physiologically incompatible systems. The purpose of this review of case studies of tubing misconnections and of current expert recommendations for safe tubing connections was to answer the following questions: In tubing connections that have the potential for misconnections between enteral and IV tubing, what are the threats to safety? What are patient outcomes following misconnections between enteral and IV tubing? What are the current recommendations for preventing misconnections between enteral and IV tubing? Following an extensive literature search and guided by 2 models of threats and errors, the authors analyzed case studies and expert opinions to identify technical, organizational, and human errors; patient-related threats; patient outcomes; and recommendations. A total of 116 case studies were found in 34 publications. Each involved misconnections of tubes carrying feedings, intended for enteral routes, to IV lines. Overwhelmingly, the recommendations were for redesign to eliminate universal connectors and prevent misconnections. Other recommendations were made, but the analysis indicates they would not prevent all misconnections. This review of the published case studies and current expert recommendations supports a redesign of connectors to ensure incompatibility between enteral and IV systems. Despite the cumulative evidence, little progress has been made to safeguard patients from tubing misconnections.

Tube Plugging Criteria for the High-pressure Heaters of Nuclear Power Plant

Energy Technology Data Exchange (ETDEWEB)

Kim, Hyungnam; Cho, Nam-Cheoul; Lee, Kuk-hee [KHNP Central Research Institute, Daejeon (Korea, Republic of)

2015-10-15

In this paper, a method to establish the tube plugging criteria of BOP heat exchangers is introduced and the tube plugging criteria for the high pressure heaters of a nuclear power plant. This method relies on the similar plugging criteria used in the steam generator tubes. Power generation field urges nuclear power plants to reduce operating and maintaining costs to remain competitive. To reduce the cost by means of preventing the lowering thermal efficiency, the inspection of balance-of-plant heat exchanger, which was treated as not important work, becomes important. The tubing materials and tube thickness of heat exchangers in nuclear power plants are selected to withstand system temperature, pressure, and corrosion. But tubes have experienced leaks and failures and plugged based upon eddy current testing (ET) results. There are some problems for plugging the heat exchanger tubes since the criterion and its basis are not clearly described. For this reason, the criteria for the tube wall thickness are addressed in order to operate the heat exchangers in nuclear power plant without trouble during the cycle. The feed water heater is a kind of heat exchanger which raises the temperature of water supplied from the condenser. The heat source of high-pressure heaters is the extraction steam from the high-pressure turbine and moisture separator re-heater. If the tube wall of the heater is broken, the feed water flowing inside the tube intrudes to shell side. This forces the turbine to be stop in order to protect it. There are many codes and standards to be referred for calculating the minimum thickness of the heat exchanger tube in the designing stage. However, the codes and standards related to show the tube plugging criteria may not exist currently. A method to establish the tube plugging criteria of BOP heat exchangers is introduced and the tube plugging criteria for the high pressure heaters of Ulchin NPP No. 3 and 4. This method relies on the similar plugging

Technique employed to seal a tube leaking in a heat exchanger of the tube type by explosives with supporting means for the adjacent tubes

International Nuclear Information System (INIS)

Larson, G.C.

1978-01-01

This invention concerns the technique employed to seal a tube leaking in a heat exchanger of the tube and tube plate type by detonating metal plugs activated by an explosive and inserted in both ends of the tube. It refers in particular to an apparatus and process in which the deformation or distortion of the adjacent tubes and tube plate ties under the effect of the explosive forces is significantly reduced [fr

Improved eddy-current inspection for steam generator tubing

International Nuclear Information System (INIS)

Dodd, C.V.; Pate, J.R.; Allen, J.D. Jr.

1989-01-01

Computer programs have been written to allow the analysis of different types of eddy-current probes and their performance under different steam generator test conditions. The probe types include the differential bobbin probe, the absolute bobbin probe, the pancake probe and the reflection probe. The generator test conditions include tube supports, copper deposits, magnetite deposits, denting, wastage, pitting, cracking and IGA. These studies are based mostly on computed values, with the limited number of test specimens available used to verify the computed results. The instrument readings were computed for a complete matrix of the different test conditions, and then the test conditions determined as a function of the readings by a least-squares technique. A comparison was made of the errors in fit and instrument drift for the different probe types. The computations of the change in instrument reading due to the defects have led to an ''inversion'' technique in which the defect properties can be computed from the instrument readings. This has been done both experimentally and analytically for each of these probe types. 3 refs., 13 figs., 1 tab

Diagnostic of corrosion defects in steam generator tubes using advanced signal processing from Eddy current testing

International Nuclear Information System (INIS)

Formigoni, Andre L.; Lopez, Luiz A.N.M.; Ting, Daniel K.S.

2009-01-01

Recently, the Brazilian Angra I PWR nuclear power plant went into a programmed shutdown for substitution of its Steam Generator (SG) which life was shortened due to stress corrosion in its tubes. The total cost of investment were around R$724 million. The signals generated during an Eddy-current Testing (ECT) inspection in SG tubes of nuclear plant allows for the localization and dimensioning of defects in the tubes. The defects related with corrosion generate complex signals that are difficult to analyze and are the most common cause in SG replacement in nuclear power plants around the world. The objective of this paper is the development of a methodology that allows for the characterization of corrosion signals by ECT inspections applied in the heat exchangers tubes of SG of a nuclear power plant. In this present work, the aim is to investigate distributed type defects by inducing controlled corrosion in sample tubes of different materials The ECT signals obtained from these samples tubes with corrosion implanted, will be analyzed using Zetec ECT equipment, the MIZ-17ET and its probes. The data acquisition will use a NI PC A/D CARD 700 card and the LabVIEW program. Subsequently, we will apply mathematical tools for signal processing like time windowed Fast Fourier transforms and Wavelets transforms, in MATLAB platform, which will allow effectiveness to remove the noises and to extract representative characteristics for the defect being analyzed. Previously obtained results as well as the proposal for the future work will be presented. (author)

An automated eddy current in-service inspection system for nuclear steam generator tubing

International Nuclear Information System (INIS)

Wells, N.S.

1981-06-01

A prototype steam generator in-service inspection system incorporating remotely-controlled instrumentation linked by a digital transmission line to an instrument and control trailer outside the reactor containment has been designed and manufactured and is presently undergoing field tests. The (Monel 400) steam generator tubes are scanned two at a time using absolute eddy current probes controlled by two remotely-operated probe drives at a scanning speed of 0.5 m/s. The probes are positioned on the tubesheet by a light-weight (1.5 kg) microprocessor-operated tubesheet walker mechanism. Digitized control and data signals are transmitted up to 300 m to the control trailer. There the control and analysis computers extract the relevant signal information and present it in condensed form as labelled graphics on CRT consoles for on-line visual assessment. Hard copy output is also provided for each tube scanned (one per minute). Condensed data is archived on magnetic tapes for additional off-line analysis and comparisons with other inspections

Eddy current testing of steam generator tubes

International Nuclear Information System (INIS)

Neumaier, P.

1981-01-01

A rotating probe is described for improving the inspection of tubes and end plate in steam generators. The method allows a representation of the whole defect, consequently the observer is able to determine directly the type of defect, signal processing in-line or off-line is possible [fr

Chest Tube Management after Surgery for Pneumothorax.

Science.gov (United States)

Pompili, Cecilia; Salati, Michele; Brunelli, Alessandro

2017-02-01

There is scant evidence on the management of chest tubes after surgery for pneumothorax. Most of the current knowledge is extrapolated from studies performed on subjects with lung cancer. This article reviews the existing literature with particular focus on the effect of suction and no suction on the duration of air leak after lung resection and surgery for pneumothorax. Moreover, the role of regulated suction, which seems to provide some benefit in reducing pneumothorax recurrence after bullectomy and pleurodesis, is discussed. Finally, a personal view on the management of chest tubes after surgery for pneumothorax is provided. Copyright © 2016 Elsevier Inc. All rights reserved.

The control of stainless steel tubes and wires of small diameter by the Eddy current method

International Nuclear Information System (INIS)

Stossel, A.; Gallet, G.

1978-01-01

Stainless steel tubes and wires with an outer diameter greater than 1 mm were studied by Eddy currents. The sensor characteristics and the detection of defects in function of frequency are presented together with the results obtained in the detection of dimensional and metallurgical defects [fr

The feasibility of a regional CTDIvol to estimate organ dose from tube current modulated CT exams

International Nuclear Information System (INIS)

Khatonabadi, Maryam; Kim, Hyun J.; Lu, Peiyun; McMillan, Kyle L.; Cagnon, Chris H.; McNitt-Gray, Michael F.; DeMarco, John J.

2013-01-01

Purpose: In AAPM Task Group 204, the size-specific dose estimate (SSDE) was developed by providing size adjustment factors which are applied to the Computed Tomography (CT) standardized dose metric, CTDI vol . However, that work focused on fixed tube current scans and did not specifically address tube current modulation (TCM) scans, which are currently the majority of clinical scans performed. The purpose of this study was to extend the SSDE concept to account for TCM by investigating the feasibility of using anatomic and organ specific regions of scanner output to improve accuracy of dose estimates. Methods: Thirty-nine adult abdomen/pelvis and 32 chest scans from clinically indicated CT exams acquired on a multidetector CT using TCM were obtained with Institutional Review Board approval for generating voxelized models. Along with image data, raw projection data were obtained to extract TCM functions for use in Monte Carlo simulations. Patient size was calculated using the effective diameter described in TG 204. In addition, the scanner-reported CTDI vol (CTDI vol,global ) was obtained for each patient, which is based on the average tube current across the entire scan. For the abdomen/pelvis scans, liver, spleen, and kidneys were manually segmented from the patient datasets; for the chest scans, lungs and for female models only, glandular breast tissue were segmented. For each patient organ doses were estimated using Monte Carlo Methods. To investigate the utility of regional measures of scanner output, regional and organ anatomic boundaries were identified from image data and used to calculate regional and organ-specific average tube current values. From these regional and organ-specific averages, CTDI vol values, referred to as regional and organ-specific CTDI vol , were calculated for each patient. Using an approach similar to TG 204, all CTDI vol values were used to normalize simulated organ doses; and the ability of each normalized dose to correlate with

Improving the calandria tubes for CANDU reactors

International Nuclear Information System (INIS)

Coleman, C.E.; Fong, R.W.L.; Doubt, G.L.

1997-01-01

CANDU calandria tubes are made from annealed Zircaloy-2 sheet formed into a cylinder and welded along its length to make the tube. The current calandria tubes have given exemplary service for many years. With more stringent regulations and the need to accommodate warm cooling water in tropical countries, we started a development program to increase the margins for failure during postulated accidents. These improvements involve increasing the tube strength and optimising the heat-transfer from an excessively hot fuel channel to the cool moderator. If the postulated accident involves a pressure tube break, it would be desirable if the calandria tube withstood the full pressure of the heat-transport system. The weakest link in current calandria tubes is the weld. Thickening the weld can increase the strength by 20% while seamless tubes can be 45% stronger than current tubes. The latter tubes can hold full system pressure for many hours without failure. If during the postulated accident the fuel and pressure tube become excessively hot but do not touch the calandria tube, the radiant heat loss must be maximised. Current calandria tubes have an absorptivity (emissivity) of about 0.2. To protect the fuel and the fuel channel we have devised a finish to the inside surface of the calandria tube that increases the emissivity to 0.7. If during the postulated accident the hot pressure tube touches the cool calandria tube, the contact conductance and the critical heat flux must be optimised to ensure nucleate boiling of the moderator at the outside surface of the calandria tube and therefore efficient exploitation of the moderator as a heat sink. In laboratory tests small ridges on the inside surface and roughening of the outside surface have been shown to increase the margins against failure and increase the possible moderator temperatures thus providing the opportunity to decrease the cost of the moderator heat-exchange system and remove restrictions on reactor operation in

Development and Technology Transfer of the Syncro Blue Tube (Gabriel) Magnetically Guided Feeding Tube

Science.gov (United States)

2017-06-01

suggestions for reducing this burden to Department of Defense, Washington Headquarters Services, Directorate for Information Operations and Reports (0704-0188...the tube to the 110 cm mark. At the 110 cm mark, secure the tube with medical tape and remove the stylet completely allowing enough tube slack ...and it provides slack that allows tube to advance distally by the effect of natural peristalsis on the bolus-sized balloon. Results: Most feeding

An integrated automatic system for the eddy-current testing of the steam generator tubes

Energy Technology Data Exchange (ETDEWEB)

Woo, Hee Gon; Choi, Seong Su [Korea Electric Power Corp. (KEPCO), Taejon (Korea, Republic of). Research Center

1995-12-31

This research project was focused on automation of steam generator tubes inspection for nuclear power plants. ECT (Eddy Current Testing) inspection process in nuclear power plants is classified into 3 subprocesses such as signal acquisition process, signal evaluation process, and inspection planning and data management process. Having been automated individually, these processes were effectively integrated into an automatic inspection system, which was implemented in HP workstation with expert system developed (author). 25 refs., 80 figs.

An integrated automatic system for the eddy-current testing of the steam generator tubes

Energy Technology Data Exchange (ETDEWEB)

Woo, Hee Gon; Choi, Seong Su [Korea Electric Power Corp. (KEPCO), Taejon (Korea, Republic of). Research Center

1996-12-31

This research project was focused on automation of steam generator tubes inspection for nuclear power plants. ECT (Eddy Current Testing) inspection process in nuclear power plants is classified into 3 subprocesses such as signal acquisition process, signal evaluation process, and inspection planning and data management process. Having been automated individually, these processes were effectively integrated into an automatic inspection system, which was implemented in HP workstation with expert system developed (author). 25 refs., 80 figs.

Photomultiplier tubes for Low Level Cerenkov Detectors

Energy Technology Data Exchange (ETDEWEB)

Strindehag, O

1965-03-15

Tube backgrounds of several 2-inch photomultiplier types having S11, 'S' , S13 and S20 cathodes are compared by measuring signal and background pulse height distributions at pulse heights corresponding to a few photo-electrons. The reference signal is generated by means of a {beta}-source and a plexiglass radiator. It is found that comparatively good results are obtained with selected tubes of the EMI types 6097B and 9514B having equivalent dark current dc values down to 10{sup -12} input lumens. Special interest is devoted to the correlation between the measured tube backgrounds and the dark current dc values of the tubes, as a good correlation between these parameters simplifies the selection of photomultiplier tubes. The equivalent dark currents of the tested tubes extend over the range 10{sup -12} to 10{sup -9} input lumens. Although the investigation deals with photomultiplier tubes intended for use in low level Cerenkov detectors it is believed that the results could be valuable in other fields where photomultiplier tubes are utilized for the detection of weak light pulses.

Photomultiplier tubes for Low Level Cerenkov Detectors

International Nuclear Information System (INIS)

Strindehag, O.

1965-03-01

Tube backgrounds of several 2-inch photomultiplier types having S11, 'S' , S13 and S20 cathodes are compared by measuring signal and background pulse height distributions at pulse heights corresponding to a few photo-electrons. The reference signal is generated by means of a β-source and a plexiglass radiator. It is found that comparatively good results are obtained with selected tubes of the EMI types 6097B and 9514B having equivalent dark current dc values down to 10 -12 input lumens. Special interest is devoted to the correlation between the measured tube backgrounds and the dark current dc values of the tubes, as a good correlation between these parameters simplifies the selection of photomultiplier tubes. The equivalent dark currents of the tested tubes extend over the range 10 -12 to 10 -9 input lumens. Although the investigation deals with photomultiplier tubes intended for use in low level Cerenkov detectors it is believed that the results could be valuable in other fields where photomultiplier tubes are utilized for the detection of weak light pulses

Steam generator tube performance: world experience with water-cooled nuclear power reactors during 1979

International Nuclear Information System (INIS)

Tatone, O.S.; Pathania, R.S.

1981-01-01

The performance of steam generator tubes in water-cooled nuclear power reactors is reviewed for 1979. Tube failures occurred at 38 of the 93 reactors surveyed. The causes of these failures and the procedures designed to deal with them are described. The defect rate, although higher than that in 1978, was still lower than the rates of the two previous years. Methods being employed to detect defects include the increased use of multifrequency eddy-current testing and a trend to full-length inspection of all tubes. To reduce the incidence of tube failure by corrosion, plant operators are turning to full-flow condensate demineralization and more leak-resistant condenser tubes. 10 tables

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

Fuel assembly and fuel cladding tube

International Nuclear Information System (INIS)

Tsutsumi, Shinro; Ito, Ken-ichi; Inagaki, Masatoshi; Nakajima, Junjiro.

1996-01-01

A fuel cladding tube is a zirconium liner tube formed by lining a pure zirconium layer on the inner side of a zirconium alloy tube. The fuel cladding tube is formed by extrusion molding of a composite billet formed by inserting a pure zirconium billet into a zirconium alloy billet. Accordingly, the pure zirconium layer and the zirconium alloy tube are strongly joined by metal bond. The fuel cladding tube has an external oxide film on the outer surface of the zirconium alloy tube and an internal oxide film on the inner side of the pure zirconium layer. The external oxide film has a thickness preferably of about 1μm. The internal oxide film has a thickness of not more than 10μm, preferably, from 1 to 5μm. With such a constitution, flaws to be formed on both inner and outer surfaces of the cladding tube upon assembling a fuel assembly can be reduced thereby enabling to reduce the amount of hydrogen absorbed to the cladding tube. (I.N.)

EXTRACSION: a system for automatic Eddy Current diagnosis of steam generator tubes in nuclear power plants

International Nuclear Information System (INIS)

Georgel, B.; Zorgati, R.

1992-01-01

Improving speed and quality of Eddy Current non-destructive testing of steam generator tubes leads to automation of all process that contribute to diagnosis. This paper describes how signal processing, pattern recognition and artificial and artificial intelligence are used to build a software package that is able to automatically provide an efficient diagnosis. (author)

Extraction: a system for automatic eddy current diagnosis of steam generator tubes in nuclear power plants

International Nuclear Information System (INIS)

Georgel, B.; Zorgati, R.

1994-01-01

Improving speed and quality of Eddy Current non-destructive testing of steam generator tubes leads to automatize all processes that contribute to diagnosis. This paper describes how we use signal processing, pattern recognition and artificial intelligence to build a software package that is able to automatically provide an efficient diagnosis. (authors). 2 figs., 5 refs

Progress in Effect of Nano-modified Coatings and Welding Process Parameters on Wear of Contact Tube for Non-copper Coated Solid Wires

Directory of Open Access Journals (Sweden)

LI Zhuo-xin

2017-12-01

Full Text Available Environment-friendly non-copper coated solid wire is the main developing trend for gas shielded solid wires, whereas wear of contact tube limits their wide application. The effect of nano-modified coatings and welding process parameters on wear of contact tube for non-copper coated solid wires was reviewed. It was found that the wear of contact tube can be reduced due to the formation of tribo-films on the rubbing surfaces of welding wires against contact tube; it is feasible to decrease contact tube wear when non-copper coated solid wires are coated with nano-modified lubricants, thereby displaying excellent lubricating and thermal or electrical conduction characteristics. The wear of contact tube increases with the increase of welding current. The wear of contact tube is worse in direct-current electrode positive (DCEP than in direct-current electrode negative (DCEN. Arc ablation and electrical erosion are the dominant wear mechanisms of contact tube.

Reducing leakage current in semiconductor devices

Energy Technology Data Exchange (ETDEWEB)

Lu, Bin; Matioli, Elison de Nazareth; Palacios, Tomas Apostol

2018-03-06

A semiconductor device includes a first region having a first semiconductor material and a second region having a second semiconductor material. The second region is formed over the first region. The semiconductor device also includes a current blocking structure formed in the first region between first and second terminals of the semiconductor device. The current blocking structure is configured to reduce current flow in the first region between the first and second terminals.

A Study on the Profile Change Measurement of Steam Generator Tubes with Tube Expansion Methods

International Nuclear Information System (INIS)

Kim, Young Kyu; Song Myung Ho; Choi, Myung Sik

2011-01-01

Steam generator tubes for nuclear power plants contain the local shape transitions on their inner or outer surface such as dent, bulge, over-expansion, eccentricity, deflection, and so on by the application of physical force during the tube manufacturing and steam generator assembling and by the sludge (that is, corrosion products) produced during the plant operation. The structural integrity of tubes will be degraded by generating the corrosive crack at that location. The profilometry using the traditional bobbin probes which are currently applied for measuring the profile change of tubes gives us basic information such as axial locations and average magnitudes of deformations. However, the three-dimensional quantitative evaluation on circumferential locations, distributional angle, and size of deformations will have to be conducted to understand the effects of residual stresses increased by local deformations on corrosive cracking of tubes. Steam generator tubes of Korean standard nuclear power plants expanded within their tube-sheets by the explosive expansion method and suffered from corrosive cracks in the early stage of power operation. Thus, local deformations of steam generator tubes at the top of tube-sheet were measured with an advanced rotating probe and a laser profiling system for the two cases where the tubes expanded by the explosive expansion method and hydraulic expansion. Also, the trends of eccentricity, deflection, and over-expansion of tubes were evaluated. The advanced eddy current profilometry was confirmed to provide accurate information of local deformations compared with laser profilometry

Research and simulation of intense pulsed beam transfer in electrostatic accelerate tube

International Nuclear Information System (INIS)

Li Chaolong; Shi Haiquan; Lu Jianqin

2012-01-01

To study intense pulsed beam transfer in electrostatic accelerate tube, the matrix method was applied to analyze the transport matrixes in electrostatic accelerate tube of non-intense pulsed beam and intense pulsed beam, and a computer code was written for the intense pulsed beam transporting in electrostatic accelerate tube. Optimization techniques were used to attain the given optical conditions and iteration procedures were adopted to compute intense pulsed beam for obtaining self-consistent solutions in this computer code. The calculations were carried out by using ACCT, TRACE-3D and TRANSPORT for different beam currents, respectively. The simulation results show that improvement of the accelerating voltage ratio can enhance focusing power of electrostatic accelerate tube, reduce beam loss and increase the transferring efficiency. (authors)

Re-examination of demonstration gas discharge tubes

International Nuclear Information System (INIS)

Maharaj, H.P.

1991-01-01

Gas discharge tubes in which electrons or ions are accelerated at voltages on the order of kilovolts to produce observable atomic effects are potential x-ray sources. These tubes come in various shapes, sizes and designs, and are still in use in science classrooms despite the decline predicted in the 1970s. Because of current applications, a representative sample consisting of fifteen tubes marketed over a recent 2-year period was reexamined for regulatory compliance, product identification and advertising. The results revealed that: poor quality control and design can affect x-ray emissions; and deficiencies exist in product identification, safe use guidelines and operating instructions. This paper reports that these findings, together with the dose estimates, implications and subjective indicators, strongly suggest a user group of unknown size is at increased risk. A combination of enhanced surveillance and promotion of user awareness strategies is adopted to reduce and possible eliminate the potential health risks

m-YouTube Mobile UI: Video Selection Based on Social Influence

Science.gov (United States)

Marcus, Aaron; Perez, Angel

The ease-of-use of Web-based video-publishing services provided by applications like YouTube has encouraged a new means of asynchronous communication, in which users can post videos not only to make them public for review and criticism, but also as a way to express moods, feelings, or intentions to an ever-growing network of friends. Following the current trend of porting Web applications onto mobile platforms, the authors sought to explore user-interface design issues of a mobile-device-based YouTube, which they call m-YouTube. They first analyzed the elements of success of the current YouTube Web site and observed its functionality. Then, they looked for unsolved issues that could give benefit through information-visualization design for small screens on mobile phones to explore a mobile version of such a product/service. The biggest challenge was to reduce the number of functions and amount information to fit into a mobile phone screen, but still be usable, useful, and appealing within the YouTube context of use and user experience. Borrowing ideas from social research in the area of social influence processes, they made design decisions aiming to help YouTube users to make the decision of what video content to watch and to increase the chances of YouTube authors being evaluated and observed by peers. The paper proposes a means to visualize large amounts of video relevant to YouTube users by using their friendship network as a relevance indicator to help in the decision-making process.

Design and array signal suggestion of array type pulsed eddy current probe for health monitoring of metal tubes

Energy Technology Data Exchange (ETDEWEB)

Shin, Young Kil [Dept. of Electrical Engineering, Kunsan National University, Kunsan (Korea, Republic of)

2015-10-15

An array type probe for monitoring metal tubes is proposed in this paper which utilizes peak value and peak time of a pulsed eddy current(PEC) signal. The probe consists of an array of encircling coils along a tube and the outside of coils is shielded by ferrite to prevent source magnetic fields from directly affecting sensor signals since it is the magnetic fields produced by eddy currents that reflect the condition of metal tubes. The positions of both exciter and sensor coils are consecutively moved automatically so that manual scanning is not necessary. At one position of send-receive coils, peak value and peak time are extracted from a sensor PEC signal and these data are accumulated for all positions to form an array type peak value signal and an array type peak time signal. Numerical simulation was performed using the backward difference method in time and the finite element method for spatial analysis. Simulation results showed that peak value increases and the peak appears earlier as the defect depth or length increases. The proposed array signals are shown to be excellent in reflecting the defect location as well as variations of defect depth and length within the array probe.

Externally finned circular tube immerse in a phase-change material

International Nuclear Information System (INIS)

Alves, C.L.F.; Ismail, K.A.R.

1985-01-01

In an attempt to increase the heat transfer rate and reduce the convective currents during the freezing of phase change materials (PCM) in storage tanks, externally finned circular tubes are studied experimentally. The parameters analysed in this work include number of fins, fin length, initial degree of superheat and freezing time

Eddy current magnetic bias x-probe qualification and inspection of steam generator Monel 400 tubing in Pickering Nuclear Generating Station

International Nuclear Information System (INIS)

Lepine, B.A.; Van Langen, J.; Obrutsky, L.

2006-01-01

This paper presents an overview of the x-probe MB 350 eddy current inspection array probe, for detection of open OD axial crack-like flaws in Monel 400 tubes at Pickering Nuclear Generating Station. This report contains a selection of inspection results from the field inspections performed with this probe during the 2003 and 2004 period at Pickering Nuclear Generating Station A and B. During the 2003 in-service eddy current inspection results of Pickering Nuclear Generating Station A (PNGS-A) Unit 2, a 13 mm (0.5 inch) long axial indication was detected by the CTR1 bobbin and CTR2-C4 array probes in Tube R25-C52 of Steam Generator (SG) 11 in the hot leg sludge pile region. An experimental magnetic bias X-probe, specially designed by Zetec for inspection of Monel 400 tubing, was deployed and the indication was characterized as a potential out diameter (OD) axially oriented crack. Post-inspection tube pulling and destructive examination confirmed the presence of an Environmentally Assisted Crack (EAC), approximately 80% deep and 13mm long. Due to the significance of this discovery, Ontario Power Generation (OPG) requested AECL to initiate a program for qualification of the X-probe MB 350 for the detection of OD axial cracks in medium to high magnetic permeability μ r Monel 400 PNGS-A and B steam generator tubing at different locations. The X-probe MB 350 subsequently has been deployed as a primary inspection probe for crack detection for PNGS steam generators. (author)

The second eddy current testing of zircaloy tube samples from the OECD Halden reactor project at Reactor Fuel Examination Facility, Tokai, JAERI

International Nuclear Information System (INIS)

Ohwada, Isao; Nishino, Yasuharu

1986-07-01

The Reactor Fuel Examination Facility in Tokai/JAERI (Japan Atomic Energy Research Institute) joined to the second round robin programme on eddy current test of the Halden/IFE. In the programme, two zircaloy tube samples with some artificial defects were provided for measurements. To clarify the locations in axial and azimuthal directions, types and dimensions of the provided artificial defects, measured signals from eddy current test were analysed in comparison with the known defects on the calibration tube. As a result, fourteen defects were determined from the measurements. Then, the location, the type and the relative dimension of them were also revealed. The results of those eddy current test are described in this paper. (author)

A database for estimating organ dose for coronary angiography and brain perfusion CT scans for arbitrary spectra and angular tube current modulation

International Nuclear Information System (INIS)

Rupcich, Franco; Badal, Andreu; Kyprianou, Iacovos; Schmidt, Taly Gilat

2012-01-01

Purpose: The purpose of this study was to develop a database for estimating organ dose in a voxelized patient model for coronary angiography and brain perfusion CT acquisitions with any spectra and angular tube current modulation setting. The database enables organ dose estimation for existing and novel acquisition techniques without requiring Monte Carlo simulations. Methods: The study simulated transport of monoenergetic photons between 5 and 150 keV for 1000 projections over 360° through anthropomorphic voxelized female chest and head (0° and 30° tilt) phantoms and standard head and body CTDI dosimetry cylinders. The simulations resulted in tables of normalized dose deposition for several radiosensitive organs quantifying the organ dose per emitted photon for each incident photon energy and projection angle for coronary angiography and brain perfusion acquisitions. The values in a table can be multiplied by an incident spectrum and number of photons at each projection angle and then summed across all energies and angles to estimate total organ dose. Scanner-specific organ dose may be approximated by normalizing the database-estimated organ dose by the database-estimated CTDI vol and multiplying by a physical CTDI vol measurement. Two examples are provided demonstrating how to use the tables to estimate relative organ dose. In the first, the change in breast and lung dose during coronary angiography CT scans is calculated for reduced kVp, angular tube current modulation, and partial angle scanning protocols relative to a reference protocol. In the second example, the change in dose to the eye lens is calculated for a brain perfusion CT acquisition in which the gantry is tilted 30° relative to a nontilted scan. Results: Our database provides tables of normalized dose deposition for several radiosensitive organs irradiated during coronary angiography and brain perfusion CT scans. Validation results indicate total organ doses calculated using our database are

Study of low vibration 4 K pulse tube cryocoolers

Science.gov (United States)

Xu, Mingyao; Nakano, Kyosuke; Saito, Motokazu; Takayama, Hirokazu; Tsuchiya, Akihiro; Maruyama, Hiroki

2012-06-01

Sumitomo Heavy Industries, Ltd. (SHI) has been continuously improving the efficiency and reducing the vibration of a 4 K pulse tube cryocooler. One advantage of a pulse tube cryocooler over a GM cryocooler is low vibration. In order to reduce vibration, both the displacement and the acceleration have to be reduced. The vibration acceleration can be reduced by splitting the valve unit from the cold head. One simple way to reduce vibration displacement is to increase the wall thickness of the tubes on the cylinder. However, heat conduction loss increases while the wall thickness increases. To overcome this dilemma, a novel concept, a tube with non-uniform wall thickness, is proposed. Theoretical analysis of this concept, and the measured vibration results of an SHI lowvibration pulse tube cryocooler, will be introduced in this paper.

Prospective estimation of organ dose in CT under tube current modulation

International Nuclear Information System (INIS)

Tian, Xiaoyu; Li, Xiang; Segars, W. Paul; Frush, Donald P.; Samei, Ehsan

2015-01-01

Purpose: Computed tomography (CT) has been widely used worldwide as a tool for medical diagnosis and imaging. However, despite its significant clinical benefits, CT radiation dose at the population level has become a subject of public attention and concern. In this light, optimizing radiation dose has become a core responsibility for the CT community. As a fundamental step to manage and optimize dose, it may be beneficial to have accurate and prospective knowledge about the radiation dose for an individual patient. In this study, the authors developed a framework to prospectively estimate organ dose for chest and abdominopelvic CT exams under tube current modulation (TCM). Methods: The organ dose is mainly dependent on two key factors: patient anatomy and irradiation field. A prediction process was developed to accurately model both factors. To model the anatomical diversity and complexity in the patient population, the authors used a previously developed library of computational phantoms with broad distributions of sizes, ages, and genders. A selected clinical patient, represented by a computational phantom in the study, was optimally matched with another computational phantom in the library to obtain a representation of the patient’s anatomy. To model the irradiation field, a previously validated Monte Carlo program was used to model CT scanner systems. The tube current profiles were modeled using a ray-tracing program as previously reported that theoretically emulated the variability of modulation profiles from major CT machine manufacturers Li et al., [Phys. Med. Biol. 59, 4525–4548 (2014)]. The prediction of organ dose was achieved using the following process: (1) CTDI vol -normalized-organ dose coefficients (h organ ) for fixed tube current were first estimated as the prediction basis for the computational phantoms; (2) each computation phantom, regarded as a clinical patient, was optimally matched with one computational phantom in the library; (3) to

Reduce chest pain using modified silicone fluted drain tube for chest drainage after video-assisted thoracic surgery (VATS) lung resection.

Science.gov (United States)

Li, Xin; Hu, Bin; Miao, Jinbai; Li, Hui

2016-02-01

The aim of this study was to assess the feasibility, efficacy and safety of a modified silicone fluted drain tube after video-assisted thoracic surgery (VATS) lung resection. The prospective randomized study included 50 patients who underwent VATS lung resection between March 2015 and June 2015. Eligible patients were randomized into two groups: experimental group (using the silicone fluted drain tubes for chest drainage) and control group (using standard drain tubes for chest drainage). The volume and characteristics of drainage, postoperative (PO) pain scores and hospital stay were recorded. All patients received standard care during hospital admission. In accordance with the exit criteria, three patients were excluded from study. The remaining 47 patients included in the final analysis were divided into two groups: experiment group (N=24) and control group (N=23). There was no significant difference between the two groups in terms of age, sex, height, weight, clinical diagnosis and type of surgical procedure. There was a trend toward less PO pain in experimental group on postoperative day (POD) 1, with a statistically significant difference. Patients in experimental group had a reduced occurrence of fever [temperature (T) >37.4 °C] compared to the control group. The silicone fluted drain tube is feasible and safe and may relieve patient PO pain and reduce occurrence of fever without the added risk of PO complications.

Limiting currents of an unneutralized magnetized electron beam in a cylindrical drift tube

International Nuclear Information System (INIS)

Thompson, J.R.; Sloan, M.L.

1978-01-01

Results of an investigation of the steady state injection of a uniform unneutralized, magnetized, relativistic electron beam into a cylindrical drift tube are presented. The space-charge-limited current and the asymptotic kinetic energy of electrons on axis is determined both numerically and analytically as a function of the input kinetic energy (γ 0 -1) mc 2 and of the ratio of beam-to-wall radii. A previously cited ''interpolation formula'' is obtained in the pencil beam limit, but more accurate limiting current expressions are developed for other cases (such as the fat beam limit) where the interpolation formula is as much as 20% in error. The corresponding axial electron energy is also found to be significantly smaller than the previously cited value of (γ/sup 1/3/ 0 -1) mc 2 except in the strong pencil beam limit

Coaxial guiding assembly for internal through-passing probe for eddy current testing of tubes

International Nuclear Information System (INIS)

Kubis, S.; Holec, P.

1989-01-01

The device features guiding cases mounted on springs provided on the peripheries with two rows of radial openings into which are wound flexible fibres parallel with the case axis. The advantage of the design is that active elements which provide the coaxial guiding of the probe are oriented in the direction of the probe movement. This significantly reduces friction between the probe and the internal wall of the tube and thereby also wear of the guide parts of the probe. (J.B.). 2 figs

On Eddy current examination (ECE) of Incoloy 800 SG tube using OD encircling and ID bobbin coil

International Nuclear Information System (INIS)

Kapoor, K.; Sunder Krishna, K.; Bakshu, S.A.

2015-01-01

The purpose of this paper is to present and compare the results of ECE carried out on steam generator tubes from OD side and ID side. During the manufacturing of the tubes Eddy current testing is being carried out using OD encircling probe as per ASTM E 571. Here the purpose of the test is to capture the manufacturing defects. The parameters of the test are optimized to achieve best sensitivity to this requirement. These tubes are then installed in the steam generator and once again ECE is carried out during installation (pre-service inspection-PSI) and during in-service inspection (ISI) by using ID bobbin coil. These tests are carried out as per ASME section V article 8 appendix 1. Here the purpose of the test is to detect wall thinning, dent, pits etc due to operation and to locate these defects (OD side or ID side). Here the operating parameters are optimized for phase separation of defects from OD and ID. These parameters are quite different from those used during the manufacturing ECE. Interpretation of the signals detected in PSI/ISI in must be done with care to correlate with defect indications detected during manufacturing. In the present study, tubes with certain manufacturing defects, detected with OD encircling test were subjected to ID bobbin coil examination. Also certain tubes with signal picked up during test from ID were examined by using the OD encircling probe. This comparison of the results provides a clear picture about the sensitivity and deficiency of the either type of test. (author)

Dose reduction in spiral CT angiography of thoracic outlet syndrome by anatomically adapted tube current modulation

International Nuclear Information System (INIS)

Mastora, I.; Remy-Jardin, M.; Remy, J.; Suess, C.; Scherf, C.; Guillot, J.P.

2001-01-01

The aim of this study was to evaluate dose reduction in spiral CT angiography of the thoracic outlet by on-line tube-current control. Prospectively, 114 patients undergoing spiral CT angiography of the subclavian artery for thoracic outlet arterial syndromes were evaluated with and without tube-current modulation at the same session (scanning parameters for the two successive angiograms, one in the neutral position and one after the postural maneuver): 140 kV; 206 mA; scan time 0.75 s; collimation 3 mm; pitch = (1). The dose reduction system was applied in the neutral position in the first 92 consecutive patients and after postural maneuver in the remaining 22 consecutive patients. Dose reduction and image quality were analyzed in the overall study group (group 1; n = 114). The influence of the arm position was assessed in 44 of the 114 patients (group 2), matched by the transverse diameter of the upper thorax. The mean dose reduction was 33 % in group 1 (range 22-40 %) and 34 % in group 2 (range 26-40 %). In group 2 the only difference in image quality was a significantly higher frequency of graininess on low-dose scans compared with reference scans whatever the patient's arm position, graded as minimal in 38 of the 44 patients (86 %). When the low-dose technique was applied after postural maneuver in group 2: (a) the mean dose reduction was significantly higher (35 vs 32 % in the neutral position; p = 0.006); (b) graininess was less frequent (82 vs 91 % in the neutral position); and (c) the percentage of graininess graded as minimal was significantly higher (83 vs 70 % in the neutral position; p = 0.2027). On-line tube-current modulation enables dose reduction on high-quality, diagnostic spiral CT angiograms of the thoracic outlet and should be applied during data acquisition in the neutral position and after postural maneuver for optimal use. (orig.)

Dose reduction in spiral CT angiography of thoracic outlet syndrome by anatomically adapted tube current modulation

Energy Technology Data Exchange (ETDEWEB)

Mastora, I.; Remy-Jardin, M.; Remy, J. [Dept. of Radiology, University Center Hospital Calmette, Lille (France); Medical Research Group, Lille (France); Suess, C.; Scherf, C. [Siemens Medical Systems, Forcheim (Germany); Guillot, J.P. [Dept. of Radiology, University Center Hospital Calmette, Lille (France)

2001-04-01

The aim of this study was to evaluate dose reduction in spiral CT angiography of the thoracic outlet by on-line tube-current control. Prospectively, 114 patients undergoing spiral CT angiography of the subclavian artery for thoracic outlet arterial syndromes were evaluated with and without tube-current modulation at the same session (scanning parameters for the two successive angiograms, one in the neutral position and one after the postural maneuver): 140 kV; 206 mA; scan time 0.75 s; collimation 3 mm; pitch = (1). The dose reduction system was applied in the neutral position in the first 92 consecutive patients and after postural maneuver in the remaining 22 consecutive patients. Dose reduction and image quality were analyzed in the overall study group (group 1; n = 114). The influence of the arm position was assessed in 44 of the 114 patients (group 2), matched by the transverse diameter of the upper thorax. The mean dose reduction was 33 % in group 1 (range 22-40 %) and 34 % in group 2 (range 26-40 %). In group 2 the only difference in image quality was a significantly higher frequency of graininess on low-dose scans compared with reference scans whatever the patient's arm position, graded as minimal in 38 of the 44 patients (86 %). When the low-dose technique was applied after postural maneuver in group 2: (a) the mean dose reduction was significantly higher (35 vs 32 % in the neutral position; p = 0.006); (b) graininess was less frequent (82 vs 91 % in the neutral position); and (c) the percentage of graininess graded as minimal was significantly higher (83 vs 70 % in the neutral position; p = 0.2027). On-line tube-current modulation enables dose reduction on high-quality, diagnostic spiral CT angiograms of the thoracic outlet and should be applied during data acquisition in the neutral position and after postural maneuver for optimal use. (orig.)

Leakproof Swaged Joints in Thin-Wall Tubing

Science.gov (United States)

Stuckenberg, F. H.; Crockett, L. K.; Snyder, W. E.

1986-01-01

Tubular inserts reinforce joints, reducing incidence of leaks. In new swaging technique, tubular inserts placed inside ends of both tubes to be joined. Made from thicker-wall tubing with outside diameter that matches inside diameter of thin tubing swaged, inserts support tube ends at joint. They ensure more uniform contact between swage fitting and tubing. New swaging technique developed for Al/Ti/V-alloy hydraulic supply lines.

Non-destructive controls in the steel tube industry

International Nuclear Information System (INIS)

Mondot, J.

1978-01-01

The main non-destructive control methods in the tube industry are reviewed: eddy currents, particularly well adapted to small tubes; magnetoscopic testing for weldless tubes; ultrasonic waves widely used for thick weldless tubes and weldings; radiography, to examine tube ends and the known questionable zones; measure of diameters by laser [fr

Characterization and implementation of OSL dosimeters for use in evaluating the efficacy of organ-based tube current modulation for CT scans of the face and orbits

Energy Technology Data Exchange (ETDEWEB)

Marsh, R. M.; Silosky, M., E-mail: michael.silosky@ucdenver.edu [Department of Radiology, University of Colorado School of Medicine, Aurora, Colorado 80045 (United States)

2015-04-15

Purpose: The purpose of this work was to characterize commercially available optically stimulated luminescent (OSL) dosimeters for general clinical applications and apply the results to the development of a method to evaluate the efficacy of a vendor-specific organ-based tube current modulation application for both phantom and clinical computed tomography (CT) scans of the face and orbits. Methods: This study consisted of three components: (1) thorough characterization of the dosimeters for CT scans in phantom, including evaluations of depletion, fading, angular dependence, and conversion from counts to absorbed dose; (2) evaluation of the efficacy of using plastic glasses to position the dosimeters over the eyes in both phantom and clinical studies; and (3) preliminary dosimetry measurements made using organ-based tube current modulation in computed tomography dose index (CTDI) and anthropomorphic phantom studies. Results: (1) Depletion effects were found to have a linear relationship with the output of the OSL dosimeters (R{sup 2} = 0.96). Fading was found to affect dosimeter readings during the first two hours following exposure but had no effect during the remaining 60-h period observed. No significant angular dependence was observed for the exposure conditions used in this study (with p-values ranging from 0.9 to 0.26 for all t-tests). Dosimeter counts varied linearly with absorbed dose when measured in the center and 12 o’clock positions of the CTDI phantoms. These linear models of counts versus absorbed dose had overlapping 95% confidence intervals for the intercepts but not for the slopes. (2) When dosimeters were positioned using safety glasses, there was no adverse effect on image quality, and there was no statistically significant difference between this placement and placement of the dosimeters directly on the eyes of the phantom (p = 0.24). (3) When using organ-based tube current modulation, the dose to the lens of the eye was reduced between 19% and

Characterization and implementation of OSL dosimeters for use in evaluating the efficacy of organ-based tube current modulation for CT scans of the face and orbits

International Nuclear Information System (INIS)

Marsh, R. M.; Silosky, M.

2015-01-01

Purpose: The purpose of this work was to characterize commercially available optically stimulated luminescent (OSL) dosimeters for general clinical applications and apply the results to the development of a method to evaluate the efficacy of a vendor-specific organ-based tube current modulation application for both phantom and clinical computed tomography (CT) scans of the face and orbits. Methods: This study consisted of three components: (1) thorough characterization of the dosimeters for CT scans in phantom, including evaluations of depletion, fading, angular dependence, and conversion from counts to absorbed dose; (2) evaluation of the efficacy of using plastic glasses to position the dosimeters over the eyes in both phantom and clinical studies; and (3) preliminary dosimetry measurements made using organ-based tube current modulation in computed tomography dose index (CTDI) and anthropomorphic phantom studies. Results: (1) Depletion effects were found to have a linear relationship with the output of the OSL dosimeters (R 2 = 0.96). Fading was found to affect dosimeter readings during the first two hours following exposure but had no effect during the remaining 60-h period observed. No significant angular dependence was observed for the exposure conditions used in this study (with p-values ranging from 0.9 to 0.26 for all t-tests). Dosimeter counts varied linearly with absorbed dose when measured in the center and 12 o’clock positions of the CTDI phantoms. These linear models of counts versus absorbed dose had overlapping 95% confidence intervals for the intercepts but not for the slopes. (2) When dosimeters were positioned using safety glasses, there was no adverse effect on image quality, and there was no statistically significant difference between this placement and placement of the dosimeters directly on the eyes of the phantom (p = 0.24). (3) When using organ-based tube current modulation, the dose to the lens of the eye was reduced between 19% and 43

Data analysis for steam generator tubing samples

International Nuclear Information System (INIS)

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

Comparison of characteristics parameters in the evaluation of wall thickness diminishing in admiralty brass tubes of the steam condenser, tested by eddy currents

International Nuclear Information System (INIS)

Obrutsky, Alba E.; Mendez, Jorge A.; Acosta, Cesar D.; Scopelliti, Jose D.

1999-01-01

This work is aimed to appraise the measure of the wall thickness diminishing in the signals evaluation obtained in the inspection of steam condenser by eddy currents. In the analysis of the obtained signals were observed in the brass tubes a great quantity of internal defects whose signal indicates that there were diminishing of the wall thickness between 80% and 100%. With all this information and analyzing the data acquired, the tubes with more important indications were selected to make a more exhaustive study of the found defectology. As first test, it was measured the thickness of the worn tubes, comparing them with the original ones that are in stock. It was verified that the tubes separated for this study presented a 30% less thickness in comparison with the new tubes. A semiquantitative chemical test (EDAX) was made to verify if it was the same material. One of the extracted tubes (066 Y1) was reinspected in order to isolate the area with indications. Once this was performed, it was decided to cut the tube to make a visual inspection and to evaluate to what type of defect corresponds to the signals obtained. In the metallography it was confirm that it was a horseshoe type defect. When performing a dimensional control test of the found real defect, it was checked that the information obtained by eddy currents regarding the diminishing of the wall thickness diminishing was valid. At a last stage of the test, it was proceed to make an study and verification of the used parameters, probes, standards and finally determine which shall be the convenient modifications to minimize errors. (author)

Investigation and application of reduced-order methods for flows study in heat exchanger tube bundles

International Nuclear Information System (INIS)

Pomarede, M.

2012-01-01

The objective of this thesis is to study the ability of model reduction for investigations of flow-induced vibrations in heat exchangers tube bundle systems.These mechanisms are a cause of major concern because heat exchangers are key elements of nuclear power plants and on-board stoke-holds.In a first part, we give a recall on heat exchangers functioning and on vibratory problems to which they are prone. Then, complete calculations leaded with the CFD numerical code Code-Saturne are carried out, first for the flow around a single circular cylinder (fixed then elastically mounted) and then for the case of a tube bundle system submitted to cross-flow. Reduced-order method POD is applied to the flow resolution with fixed structures. The obtained results show the efficiency of this technique for such configurations, using stabilization methods for the dynamical system resolution in the tube-bundle case. Multiphase-POD, which is a method enabling the adaptation of POD to fluid-structure interactions, is applied. Large displacements of a single cylinder elastically mounted under cross-flow, corresponding to the lock-in phenomenon,are well reproduced with this reduction technique. In the same way, large displacements of a confined moving tube in a bundle are shown to be faithfully reconstructed.Finally, the use of model reduction is extended to parametric studies. First, we propose to use the method which consists in projecting Navier-Stokes equations for several values of the Reynolds number on to a unique POD basis. The results obtained confirm the fact that POD predictability is limited to a range of parameter values. Then, a basis interpolation method, constructed using Grassmann manifolds and allowing the construction of a POD basis from other pre-calculated basis, is applied to basic cases. (author)

Studies on defect detectability in banded stainless steel tubes

International Nuclear Information System (INIS)

Shyamsunder, M.T.; Rao, B.P.C.; Babu Rao, C.; Jayakumar, T.; Kalyanasundaram, P.; Baldev Raj

1996-01-01

During inspection of one batch of stainless steel cladding tubes, a few of the tubes gave rise to continuous large amplitude indications throughout the length of the tube. It was observed that the presence of any defects in such tubes would be impossible to detect, due to the poor signal-to-noise ratio. Detailed investigations regarding the surface profile of the tubes were carried out using a novel technique called the projected interferometry method revealed periodic diametral variations and the same were further confirmed by cross sectional profiling. The feasibility of detecting defects in such banded tubes, using eddy current testing were carried out on tubes with artificial defects. This paper discusses the use of three different eddy current methods and their relative performances for inspection. The specific advantages of the phased array eddy current testing method in unambiguous defect detection in situations similar to the one encountered during the present investigations are also discussed. (author)

Fetal doses to pregnant patients from CT with tube current modulation calculated using Monte Carlo simulations and realistic phantoms

International Nuclear Information System (INIS)

Gu, J.; George Xu, X.; Caracappa, P. F.; Liu, B.

2013-01-01

To investigate the radiation dose to the fetus using retrospective tube current modulation (TCM) data selected from archived clinical records. This paper describes the calculation of fetal doses using retrospective TCM data and Monte Carlo (MC) simulations. Three TCM schemes were adopted for use with three pregnant patient phantoms. MC simulations were used to model CT scanners, TCM schemes and pregnant patients. Comparisons between organ doses from TCM schemes and those from non-TCM schemes show that these three TCM schemes reduced fetal doses by 14, 18 and 25 %, respectively. These organ doses were also compared with those from ImPACT calculation. It is found that the difference between the calculated fetal dose and the ImPACT reported dose is as high as 46 %. This work demonstrates methods to study organ doses from various TCM protocols and potential ways to improve the accuracy of CT dose calculation for pregnant patients. (authors)

A Method to Establishing Tube Plugging Criterion for Heat Exchangers with Straight Tubes

Energy Technology Data Exchange (ETDEWEB)

Kim, Hyungnam [KHNP CRI, Daejeon (Korea, Republic of)

2016-10-15

The difference of thermal expansion coefficients between the shell and tube materials causes the stress in axial direction of tube. Because of the axial stress due to thermal load, the straight tubes are used for heat exchangers operated in low temperature such as CCW (Component Cooling Water) heat exchangers and condensers. It is inevitable for the materials of the components to be degraded as the power plants become older. The degradation accompanies increasing maintenance cost as well as creating safety issues. The materials and wall thickness of heat exchanger tubes in nuclear power plants are selected to withstand system temperature, pressure, and corrosion. There are many codes and standards to be referred for calculating the minimum thickness of the heat exchanger tube in the designing stage. However, the codes and standards related to show the tube plugging criteria may not exist currently. In this paper, a method to establish the tube plugging criteria of BOP heat exchangers, which is based on the USNRC Regulatory Guide 1.121, is introduced and the tube plugging criteria for the TPCCW heat exchanger of Yonggwang NPP No. 1 and 2. A method to establish the tube plugging criteria of heat exchangers with straight tubes are introduced based on the USNRC Regulatory Guide 1.121. As an example, the tube plugging criterion for the CCW heat exchanger of a nuclear power plant is provided.

Numerical simulations of eddy current testing signals of steam generator tubes by 3-D finite element method

International Nuclear Information System (INIS)

Sakai, Takayuki; Soneda, Naoki

1996-01-01

In every inspection of Japanese PWR plants, all of steam generator tubes are inspected using Eddy Current Testing (ECT) method. However, the relationships between the ECT signals and the defect shapes are known only for the representative shapes of defects. In order to improve the reliability of inspections and the capability of ECT probes, development of numerical simulation technique of the ECT signals for arbitrarily shaped defects is essential. In this study, three-dimensional finite element code is developed to simulate the ECT signals for any kinds of defects in the SG tubes. The code is fully vectorized so that it runs on the supercomputers very efficiently. The simulation results agree very well with the experimental results. Sensitivity analyses are performed to investigate the relationships between the defect shapes and the ECT signals. (author)

Improved separation with the intermittently pressed tubing of multilayer coil in type-I counter-current chromatography.

Science.gov (United States)

Yang, Yi; Yang, Jiao; Fang, Chen; Wang, Jihui; Gu, Dongyu; Tian, Jing; Ito, Yoichiro

2018-05-25

The intermittently pressed tubing was introduced in type-I counter-current chromatographic system as the separation column to improve the separation performance in the present study. The separations were performed with two different solvent systems composed of 1-butanol-acetic acid-water (4:1:5, v/v) (BAW) and hexane-ethyl acetate-methanol-0.1 M HCl (1:1:1:1, v/v) (HEMW) using dipeptides and DNP-amino acids as test samples, respectively. The chromatographic performance was evaluated in terms of retention of the stationary phase (Sf), theoretical plate (N) and peak resolution (Rs). In general, the type-I planetary motion with the multilayer coil of non-modified standard tubing can yield the best separation at a low revolution speed of 200 rpm with lower flow rate. The present results with intermittently pressed tubing indicated that the performance was also optimal at the revolution speed of 200 rpm where the lower flow rate was more beneficial to retention of stationary phase and resolution. In the moderately hydrophobic two-phase solvent system composed of hexane-ethyl acetate-metanol-0.1 M hydrochloric acid (1:1:1:1, v/v), DNP-amino acids were separated with Rs at 1.67 and 1.47, respectively, with 12.66% of stationary phase retention at a flow rate of 0.25 ml/min. In the polar solvent system composed of 1-butanol-acetic acid-water (4:1:5, v/v), dipeptide samples were resolved with Rs at 2.18 and 18.75% of stationary phase retention at a flow rate of 0.25 ml/min. These results indicate that the present system substantially improves the separation efficiency of type-I counter-current chromatographic system. Published by Elsevier B.V.

Models for Automated Tube Performance Calculations

International Nuclear Information System (INIS)

Brunkhorst, C.

2002-01-01

High power radio-frequency systems, as typically used in fusion research devices, utilize vacuum tubes. Evaluation of vacuum tube performance involves data taken from tube operating curves. The acquisition of data from such graphical sources is a tedious process. A simple modeling method is presented that will provide values of tube currents for a given set of element voltages. These models may be used as subroutines in iterative solutions of amplifier operating conditions for a specific loading impedance

Nondestructive inspection of the tubes of TRIGA IPR-R1 reactor heat exchanger by eddy current testing

International Nuclear Information System (INIS)

Silva Junior, Silverio F.; Silva, Roger F.; Oliveira, Paulo F.; Barreto, Erika S.; Ribeiro, Isabela G.; Fraiz, Felipe C.

2013-01-01

The IPR-R1 TRIGA MARK 1 reactor is an open pool type reactor, cooled light water. It is used for research activities, personnel training and radioisotopes production, in operation since 1960 at the Nuclear Technology Development Center - CDTN/CNEN. It operates at a maximum thermal power of 100 kW and usually, the fuel cooling is done by natural circulation. If necessary, an external auxiliary cooling system, with a shell-and-tube type heat exchanger, can be used to improve the water heat removal. As part of the ageing management program of the reactor, a nondestructive evaluation of their heat exchanger stainless steel tubes will be performed, in order to verify its integrity. The examinations will be performed using the eddy current test method, which allows the detection and characterization of structural discontinuities in the wall of the tubes, if existing. For this purpose, probes and reference standards were designed and manufactured at CDTN facilities and test procedures were established and validated. In this paper, a description of the proposed infrastructure as well as the test methodology to be used in the examinations are presented and discussed. (author)

Operating performance of CANDU pressure tubes

International Nuclear Information System (INIS)

Cheadle, B.A.; Price, E.G.

1989-04-01

The performance of Zircaloy-2 and Zr-2.5 Nb pressure tubes in CANDU reactors is reviewed. The accelerated hydriding of Zircaloy-2 in reducing water chemistries can lower the toughness of this material and it is essential that defect-initiating phenomena, such as hydride blister formation from pressure tube to calandria tube contact, be prevented. Zr-2.5 Nb pressure tubes are performing well with low rates of hydrogen pick-up and good retention of material properties

Eddy current detection of spacers in the fuel channels of CANDU nuclear reactors

International Nuclear Information System (INIS)

Krause, T.W.; Schankula, J.; Sullivan, S.P.

2002-01-01

Garter Spring (GS) spacers in the fuel channels of CANDU nuclear reactors maintain separation between the hot pressure tube and surrounding moderator cooled calandria tube. Eddy current detection of the four GSs provides assurance that spacers are at or close to design positions and are performing their intended function of maintaining a non-zero gap between pressure tube and calandria tube. Pressure tube constrictions, resulting from relatively less diametral creep at end-of-fuel bundle locations, also produce large eddy current signals. Large constrictions, present in higher service pressure tubes, can produce signals that are 10 times larger than GS signals, reducing GS detectability to 30% in standard GS-detect probes. The introduction of field-focussing elements into the design of the standard GS detection eddy current probe has been used to recover the detectability of GS spacers by increasing the signal amplitude obtained from GSs relative to that from constrictions by a factor of 10. The work presented here compares laboratory, modelling and in-reactor measurements of GS and constriction signals obtained from the standard probe with that obtained from field-focussed eddy current probe designs. (author)

Development of Zr-2.5Nb pressure tubes for Advanced CANDU Reactor

International Nuclear Information System (INIS)

Bickel, G.A.; Griffiths, M.; Douchant, A.; Douglas, S.; Woo, O.T.; Buyers, A.

2010-01-01

In an Advanced CANDU Reactor (ACR), pressure tubes of cold-worked Zr-2.5Nb materials will be used in the reactor core to contain the fuel bundles and the light water coolant. They will be subjected to higher temperature, pressure and flux than that in a CANDU reactor. In order to ensure that these tubes will perform acceptably over their 30-year design life in such an environment, a manufacturing process has been developed to produce 6.5 mm thick ACR pressure tubes with optimized chemical composition, improved mechanical properties and in-reactor behaviour. The test and examination results show that, when compared with current in-service pressure tubes, the mechanical properties of ACR pressure tubes are significantly improved. Based on previous experience with CANDU reactor pressure tubes an assessment of the grain structure and texture indicates that the in-reactor creep deformation will be improved also. Analysis of the distribution of texture parameters from a trial batch of 26 tubes shows that the variability is reduced relative to tubes fabricated in the past. This reduction in variability together with a shift to a coarser grain structure will result in a reduction in diametral creep design limits and thus a longer economic life for the fuel channels of the advanced CANDU reactor. (author)

Evaluation of Two Passes Cold Pilgering Property for PLUS7TM Guide Thimble and Instrumentation Tubing

Energy Technology Data Exchange (ETDEWEB)

Park, Min Young; Park, Ki Bum; Kim, In Kyu; Lee, Young Hee; Kahng, Jong Yeol [KEPCO Nuclear Fuel Co., Daejeon (Korea, Republic of)

2015-05-15

The thermo-mechanical property of zirconium alloy tube is well known to be influenced by pilgering pass schedule and its tooling; thus the control of its microstructure and mechanical property in the final tube production stage for nuclear fuel applications is a major concern of tube manufacture. To fabricate final tube, the 3 passes pilgering is applied in general by using TREX(Tube Reduced EXtrusion), 63.5mm outer diameter(OD), in KEPCO NF and most of Zr tube manufacturing companies. They are also taking big efforts to reduce pilgering step for the sake of increasing the efficiency of production in the forming stage of tube. The objective of this study is to develop two passes of pilgering schedule from the conventional three passes of pilgering schedule for manufacturing the Guide Thimble and Instrumentation tube conforming to specification, which are newly developing component for the advanced nuclear fuel assembly in KEPCO NF. CSR, hydride orientation, and structural integrity are well conformed to the desired targets so it is expected that both die and mandrel were newly designed for the PLUS7TM guide thimble and instrumentation tube with higher Q factor for two passes of pilgering at 50LC and 25LC pilger machine, instead of three passes of pilgering, are able to be applicable to this design of fuel component. If developed two passes pilgering is applied to current manufacturing process, it would improve not only productivity but also yield rate by reducing 3 steps(pilgering, heat-treatment, pickiling and cleaning) of manufacturing process. But additional tests(including in-pile test) should be performed in order to evaluate integrity in reactor.

Attenuation-based size metric for estimating organ dose to patients undergoing tube current modulated CT exams

Energy Technology Data Exchange (ETDEWEB)

Bostani, Maryam, E-mail: mbostani@mednet.ucla.edu; McMillan, Kyle; Lu, Peiyun; Kim, Hyun J.; Cagnon, Chris H.; McNitt-Gray, Michael F. [Departments of Biomedical Physics and Radiology, David Geffen School of Medicine, University of California, Los Angeles, Los Angeles, California 90024 (United States); DeMarco, John J. [Department of Radiation Oncology, University of California, Los Angeles, Los Angeles, California 90095 (United States)

2015-02-15

Purpose: Task Group 204 introduced effective diameter (ED) as the patient size metric used to correlate size-specific-dose-estimates. However, this size metric fails to account for patient attenuation properties and has been suggested to be replaced by an attenuation-based size metric, water equivalent diameter (D{sub W}). The purpose of this study is to investigate different size metrics, effective diameter, and water equivalent diameter, in combination with regional descriptions of scanner output to establish the most appropriate size metric to be used as a predictor for organ dose in tube current modulated CT exams. Methods: 101 thoracic and 82 abdomen/pelvis scans from clinically indicated CT exams were collected retrospectively from a multidetector row CT (Sensation 64, Siemens Healthcare) with Institutional Review Board approval to generate voxelized patient models. Fully irradiated organs (lung and breasts in thoracic scans and liver, kidneys, and spleen in abdominal scans) were segmented and used as tally regions in Monte Carlo simulations for reporting organ dose. Along with image data, raw projection data were collected to obtain tube current information for simulating tube current modulation scans using Monte Carlo methods. Additionally, previously described patient size metrics [ED, D{sub W}, and approximated water equivalent diameter (D{sub Wa})] were calculated for each patient and reported in three different ways: a single value averaged over the entire scan, a single value averaged over the region of interest, and a single value from a location in the middle of the scan volume. Organ doses were normalized by an appropriate mAs weighted CTDI{sub vol} to reflect regional variation of tube current. Linear regression analysis was used to evaluate the correlations between normalized organ doses and each size metric. Results: For the abdominal organs, the correlations between normalized organ dose and size metric were overall slightly higher for all three

Combining automatic tube current modulation with adaptive statistical iterative reconstruction for low-dose chest CT screening.

Science.gov (United States)

Chen, Jiang-Hong; Jin, Er-Hu; He, Wen; Zhao, Li-Qin

2014-01-01

To reduce radiation dose while maintaining image quality in low-dose chest computed tomography (CT) by combining adaptive statistical iterative reconstruction (ASIR) and automatic tube current modulation (ATCM). Patients undergoing cancer screening (n = 200) were subjected to 64-slice multidetector chest CT scanning with ASIR and ATCM. Patients were divided into groups 1, 2, 3, and 4 (n = 50 each), with a noise index (NI) of 15, 20, 30, and 40, respectively. Each image set was reconstructed with 4 ASIR levels (0% ASIR, 30% ASIR, 50% ASIR, and 80% ASIR) in each group. Two radiologists assessed subjective image noise, image artifacts, and visibility of the anatomical structures. Objective image noise and signal-to-noise ratio (SNR) were measured, and effective dose (ED) was recorded. Increased NI was associated with increased subjective and objective image noise results (PASIR levels (PASIR had average subjective image noise scores and nearly average anatomical structure visibility scores, with a mean objective image noise of 23.42 HU. The EDs for groups 1, 2, 3 and 4 were 2.79 ± 1.17, 1.69 ± 0.59, 0.74 ± 0.29, and 0.37 ± 0.22 mSv, respectively. Compared to group 1 (NI = 15), the ED reductions were 39.43%, 73.48%, and 86.74% for groups 2, 3, and 4, respectively. Using NI = 30 with 50% ASIR in the chest CT protocol, we obtained average or above-average image quality but a reduced ED.

Demonstration for the Applicability of the EPRI ETSS on the SG Tube Wear Defects Formed at the Tube Support Structure

International Nuclear Information System (INIS)

Shin, Ki Seok; Cheon, Keun Young; Nam, Min Woo; Min, Kyong Mahn

2013-01-01

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 tubes

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

Measurements of electrically exploded tubes

International Nuclear Information System (INIS)

Shearer, J.W.; Hartman, C.W.; Munger, R.H.; Gullickson, R.L.; Trimble, D.O.; Cheng, D.Y.

1975-01-01

The dynamics of electrically exploded tubes were investigated, principally by means of current measurements and flash x-ray pictures. The pinch effect was observed on the tube motion. Pileup of the imploding tube metal was seen on axis. An approximate analytical model can be roughly fitted to the data, but a more complete fit can be obtained with detailed numerical codes. Application of the results to the planning of future gas-embedded Z-pinch experiments is discussed. (U.S.)

New eddy current testing system in steam generator tubes

International Nuclear Information System (INIS)

Nagata, Yasuyuki; Shimone, Junri; Maeda, Kotaro; Harada, Yutaka; Murakami, Ryuji

2003-01-01

Eddy Current Testing (ECT) technique is applied to PWR Steam Generator (SG) tubes during refueling outage inspection. Bobbin type probe is generally used for the inspection, but it cannot provide sufficient detectability for very tight cracks. NEL, R/D Tech (Canada) and AECL (Canada) jointly developed new ECT probe. The probe is transmit and receive type array probe. It has axial defect detection mode and circumferential defect detection mode. Its inspection speed is as fast as conventional bobbin probe, and detectability performance is same or better than performance of rotating pancake coil (RPC) probe, which is used for detailed inspection. As a tester of the new probe, we have developed new ECT tester TC7700. It is able to transmit composite wave from the 4 independent oscillators (simultaneous excitation system) compared with the conventional inspection system. As regarding for field inspection system, we have integrated Zetec (USA) probe positioner, probe pusher and R/D Tech TC7700. We are also developing new analysis software. The software has automated data screening function, which can deal with large amount of data compared with conventional bobbin probe. We plan to perform a large-scale field trial using the probe and new system in near future. (author)

Maximization of bremsstrahlung and K-series production efficiencies in flash x-ray tubes

International Nuclear Information System (INIS)

Krehl, P.

1986-01-01

Historically, x-ray output of flash x-ray tubes was maximized empirically by changing the electrode geometry and varying the capacitance of the pulse generator. With the advent of high-voltage, low-impedance transmission lines, short-duration, high-current pulses could be generated with ease. An appropriate line scaling should assure that dose maximization is not reached at the expense of pulse prolongation which would reduce stop motion capability, but rather that dose rate should be maximized. Additionally, anode evaporation in the arc phase should be minimized to enhance tube life

Eddy currents inspection of CANDU steam generator' tubes using Zetec's ZR-1 Robot: experience in Romania

Energy Technology Data Exchange (ETDEWEB)

Hower, S. [Zetec Inc., Quebec, Quebec (Canada); Serban, M. [CNE-Prod U1 Cernavoda (Romania); Vladu, L. [Compcontrol Ing., Bucharest (Romania)

2006-07-01

'Full text:' The paper introduces the new ZR-1 Robot System for Inspection and Maintenance/Repair from Zetec that combines the newest state-of-the-art robotics technology with Zetec experience-based innovation to address the needs for inspection and repair of steam generators. The multipurpose ZR-1 can be easily installed to perform the necessary eddy current inspection and remain installed ready for follow-up maintenance and repair. It has superior technical performances and a modular three axis motion of arm that enables 100% coverage of tube sheet. Automated, repeatable, and precise positioning of toolheads, ensures accurate delivery and reducing costly rework and reduces inspection time by 30%. The modular, lightweight, and portable design permits easy assembly and disassembly through small openings and it reduces setup/tear down time by 30%. The first deployment of the new ZR-1 Robot was made in September 2004 at the Cernavoda NPP inspection outage. The Cernavoda plant has four Advanced 600 MW CANDU-design generators that have been in service since 1996. The paper presents also the Zetec's filed experience and customer experience with this system. It describes the equipment setup in Cernavoda's generator mock-up, functional testes and calibration. Finally, provides details on the execution of the inspection, options for standardizing the inspection techniques and conclusions. (author)

Framatome recent developments and application on site in NDE of steam generator tubes

International Nuclear Information System (INIS)

Bieth, M.

1986-01-01

The increasing needs concerning the follow up and expertise of PWR steam generator (SG) tubing have led Framatome to develop a quick on-site intervention mobile unit, which could implement any current technique and equipment. Besides, Framatome has developed several non destructrive examination methods to solve the specific problems encountered in service on the SG tubes: profilometry of the SG tubes by eddy current. Inside and above the tube sheet, eddy current inspection of tube sleeving by ultrasonic testing and eddy current

Optimization of Tube Current in Cone-beam Computed Tomography for the Detection of Vertical Root Fractures with Different Intracanal Materials.

Science.gov (United States)

Gaêta-Araujo, Hugo; Silva de Souza, Gabriela Queiroz; Freitas, Deborah Queiroz; de Oliveira-Santos, Christiano

2017-10-01

There is no consensus about the accuracy of cone-beam computed tomography (CBCT) for detecting vertical root fractures (VRFs), nor is there certainty about the isolated effect of different tube current parameters on the diagnosis of VRF through CBCT scans. This study aimed to evaluate how tube current affects the detection of VRF on CBCT examinations in the absence of intracanal materials and in the presence of gutta-percha (GP) and metal (MP) or fiberglass (FP) intracanal posts. The sample consisted of 320 CBCT scans of tooth roots with and without VRF divided into 8 groups: no fracture/no intracanal material; no fracture + GP; no fracture + MP; no fracture + FP; fracture/no intracanal material; fracture + GP; fracture + MP; fracture + FP. The scans were acquired with an OP300 unit using 4 different milliamperes (4 mA, 8 mA, 10 mA, 13 mA). Five oral radiologists analyzed the images. The area under the receiver operating characteristic curve (Az), sensitivity, specificity, positive and negative predictive values, and interobserver agreement were calculated. Diagnostic performance for the different milliamperes tested was similar for teeth without root filling materials or with FP. Teeth with GP and MP showed the highest Az values for 8 mA and 10 mA, respectively. For teeth with MP, specificity was significantly higher when 10 mA was used. For teeth without root filling materials or with FP, the use of a reduced milliampere does not seem to influence the detection of VRF in a significant manner. For teeth with GP and MP, an increased milliampere may lead to increased diagnostic performance. Copyright © 2017 American Association of Endodontists. Published by Elsevier Inc. All rights reserved.

WWER Steam Generators Tubing Performance and Aging Management

International Nuclear Information System (INIS)

Trunov, Nikolay B.; Davidenko, Stanislav E.; Grigoriev, Vladimir A.; Popadchuk, Valery S.; Brykov, Sergery I.; Karzov, Georgy P.

2006-01-01

At WWER NPPs the horizontal steam generators (SGs), are used that differ in design concept from vertical SGs mostly used at western NPPs. Reliable operation of SG heat-exchanging tubes is the crucial worldwide problem for NPP of various types. According to the operation feedback the water chemistry is the governing factor affecting operability of SG tubing. The secondary side corrosion is considered to be the main mechanism of SG heat-exchanging tubes damage at WWER plants. To make the assessment of the tubing integrity the combination of pressure tests and eddy-current tests is used. Assessment of the tubing performance is an important part of SG life extension practice. The given paper deals with the description of the tube testing strategy and the approach to tube integrity assessment based on deterministic and probabilistic methods of fracture mechanics. Requirements for eddy-current test are given as well. Practice of condition monitoring and implementing the database on steam generators operation are presented. The approach to tubes plugging criteria is described. The research activities on corrosion mechanism studies and residual lifetime evaluation are mentioned. (authors)

Gas tube-switched high voltage DC power converter

Science.gov (United States)

She, Xu; Bray, James William; Sommerer, Timothy John; Chokhawala, Rahul

2018-05-15

A direct current (DC)-DC converter includes a transformer and a gas tube-switched inverter circuit. The transformer includes a primary winding and a secondary winding. The gas tube-switched inverter circuit includes first and second inverter load terminals and first and second inverter input terminals. The first and second inverter load terminals are coupled to the primary winding. The first and second inverter input terminals are couplable to a DC node. The gas tube-switched inverter circuit further includes a plurality of gas tube switches respectively coupled between the first and second inverter load terminals and the first and second inverter input terminals. The plurality of gas tube switches is configured to operate to generate an alternating current (AC) voltage at the primary winding.

Angular on-line tube current modulation in multidetector CT examinations of children and adults: The influence of different scanning parameters on dose reduction

International Nuclear Information System (INIS)

Papadakis, Antonios E.; Perisinakis, Kostas; Damilakis, John

2007-01-01

The purpose of this study was to assess the potential of angular on-line tube current modulation on dose reduction in pediatric and adult patients undergoing multidetector computed tomography (MDCT) examinations. Five physical anthropomorphic phantoms that simulate the average individual as neonate, 1-year-old, 5-year-old, 10-year-old, and adult were employed in the current study. Phantoms were scanned with the use of on-line tube current modulation (TCM). Percent dose reduction (%DR) factors achieved by applying TCM, were determined for standard protocols used for head and neck, shoulder, thorax, thorax and abdomen, abdomen, abdomen and pelvis, pelvis, and whole body examinations. A preliminary study on the application of TCM in MDCT examinations of adult patients was performed to validate the results obtained in anthropomorphic phantoms. Dose reduction was estimated as the percentage difference of the modulated milliamperes for each scan and the preset milliamperes prescribed by the scan protocol. The dose reduction in children was found to be much lower than the corresponding reduction achieved for adults. For helical scans the %DR factors, ranged between 1.6% and 7.4% for the neonate, 2.9% and 8.7% for the 1-year old, 2% and 6% for the 5-year-old, 5% and 10.9% for the 10-year-old, and 10.4% and 20.7% for the adult individual. For sequential scans the corresponding %DR factors ranged between 1.3% and 6.7%, 4.5% and 11%, 4.2% and 6.6%, 6.4% and 12.3%, and 8.9% and 23.3%, respectively. Broader beam collimations are associated with decreased %DR factors, when other scanning parameters are held constant. TCM did not impair image noise. In adult patients, the %DR values were found to be in good agreement with the corresponding results obtained in the anthropomorphic adult phantom. In conclusion, on-line TCM may be considered as a valuable tool for reducing dose in routine CT examinations of pediatric and adult patients. However, the dose reduction achieved with TCM

Electron emission regulator for an x-ray tube filament

International Nuclear Information System (INIS)

Daniels, H.E.; Randall, H.G.

1982-01-01

An x-ray tube ma regulator has an scr phase shift voltage regulator supplying the primary winding of a transformer whose secondary is coupled to the x-ray tube filament. Prior to initiation of an x-ray exposure, the filament is preheated to a temperature corresponding substantially to the electron emissivity needed for obtaining the desired tube ma during an exposure. During the preexposure interval, the phase shift regulator is controlled by a signal corresponding to the sum of signals representative of the voltage applied to the filament transformer, the desired filament voltage and the space charge compensation needed for the selected x-ray tube anode to cathode voltage. When an exposure is initiated, control of the voltage regulator is switched to a circuit that responds to the tube current by controlling the amount of phase shift and, hence, the voltage supplied to the transformer. Transformer leakage current compensation is provided during the exposure interval with a circuit that includes an element whose impedance is varied in accordance with the anode-to-cathode voltage setting so the element drains off tube current as required to cancel the effect of leakage current variations

Extending service life of steam generators by sleeving tubes

International Nuclear Information System (INIS)

Gutzwiller, J.E.

1982-01-01

Steam generator tubes that are failing due to IGA in the tubesheet crevice can be kept in service by using the basic sealable sleeve design developed by BandW. Variations of the present sleeve design could significantly reduce the number of tubes that must be plugged each year. Sleeving had the potential of keeping 28 percent more tubes in service during 1979. Lowering the overall rate at which tubes are removed from service by plugging will reduce the probability of having to derate the plant or replace the steam generator. Considering tomorrow's replacement power costs, sleeving to keep tubes in service is a practical and sound investment

Gastrostomy Tube (G-Tube)

Science.gov (United States)

... any of these problems: a dislodged tube a blocked or clogged tube any signs of infection (including redness, swelling, or warmth at the tube site; discharge that's yellow, green, or foul-smelling; fever) excessive bleeding or drainage from the tube site severe abdominal pain lasting ...

SG tube identification

International Nuclear Information System (INIS)

Hoogstraten, P. van

1994-01-01

A ''Tracker'' system is described which is designed to identify any tube in a reactor steam generator quickly and safely. Occupational radiation doses to maintenance workers are reduced by using a Tracker and emergency down times are shortened. The system employs a television camera and light source in a stainless steel box with a large window. Both the camera and spotlight can be panned and tilted to reach any point on the tubesheet and are remotely controlled. An operator at a safe working distance can identify any tube visible on a real time video by comparison with the tubesheet pattern stored earlier in the computer memory. The identified tube can then be spotlighted and dealt with quickly by a maintenance worker inside the channel head. (UK)

Efficacy of plastic mesh tubes in reducing herbivory damage by the invasive nutria (Myocastor coypus) in an urban restoration site

Science.gov (United States)

Sheffels, Trevor R.; Systma, Mark D.; Carter, Jacoby; Taylor, Jimmy D.

2014-01-01

The restoration of stream corridors is becoming an increasingly important component of urban landscape planning, and the high cost of these projects necessitates the need to understand and address potential ecological obstacles to project success. The nutria(Myocastor coypus) is an invasive, semi-aquatic rodent native to South America that causes detrimental ecological impacts in riparian and wetland habitats throughout its introduced range, and techniques are needed to reduce nutria herbivory damage to urban stream restoration projects. We assessed the efficacy of standard Vexar® plastic mesh tubes in reducing nutria herbivory damage to newly established woody plants. The study was conducted in winter-spring 2009 at Delta Ponds, a 60-ha urban waterway in Eugene, Oregon. Woody plants protected by Vexar® tubes demonstrated 100% survival over the 3-month initial establishment period, while only 17% of unprotected plantings survived. Nutria demonstrated a preference for black cottonwood (Populus balsamifera ssp trichocarpa) over red osier dogwood (Cornussericea) and willow (Salix spp). Camera surveillance showed that nutria were more active in unprotected rather than protected treatments. Our results suggest that Vexar® plastic mesh tubing can be an effective short-term herbivory mitigation tool when habitat use by nutria is low. Additionally, planting functionally equivalent woody plant species that are less preferred by nutria, and other herbivores, may be another method for reducing herbivory and improving revegetation success. This study highlights the need to address potential wildlife damage conflicts in the planning process for stream restoration in urban landscapes.

Integrity Analysis of Damaged Steam Generator Tubes

International Nuclear Information System (INIS)

Stanic, D.

1998-01-01

Variety of degradation mechanisms affecting steam generator tubes makes steam generators as one of the critical components in the nuclear power plants. Depending of their nature, degradation mechanisms cause different types of damages. It requires performance of extensive integrity analysis in order to access various conditions of crack behavior under operating and accidental conditions. Development and application of advanced eddy current techniques for steam generator examination provide good characterization of found damages. Damage characteristics (shape, orientation and dimensions) may be defined and used for further evaluation of damage influence on tube integrity. In comparison with experimental and analytical methods, numerical methods are also efficient tools for integrity assessment. Application of finite element methods provides relatively simple modeling of different type of damages and simulation of various operating conditions. The stress and strain analysis may be performed for elastic and elasto-plastic state with good ability for visual presentation of results. Furthermore, the fracture mechanics parameters may be calculated. Results obtained by numerical analysis supplemented with experimental results are the base for definition of alternative plugging criteria which may significantly reduce the number of plugged tubes. (author)

Internal ultrasonic testing of steam generator tubes

International Nuclear Information System (INIS)

Furlan, J.; Soleille, G.; Chalaye, H.

1983-01-01

The ''in situ'' inspection of steam generator tubes uses generally Foucault currents before starting and along its life. This inspection aims at searching cracks and corrosion defects. The Foucault current method is quite badly adapted to ''closed crack'' detection, for it doesn't introduce neither resistivity or magnetic permeability variation, or lack of matter. More, it is sensible to the magnetic properties of the tube itself and to its environment (tubular or support plates). It is why, this first systematic inspection has to be completed by an ultrasonic one allowing to bring new elements in the uncertain cases. A device with an internal probe has been developed. It ''lights'' the tube wall with the aid of a transducer of which beam reflects on a mirror. Operating conditions are the same as for Foucault current testing, that is to say the probe moves inside the tube without rotation of the device (bent parts are excluded) [fr

Stabilization of a Nb3Sn persistent current switch

International Nuclear Information System (INIS)

Urata, M.; Maeda, H.; Nakayama, S.; Yoneda, E.; Oda, Y.; Kumano, T.; Aoki, N.; Tomisaki, T.; Kabashima, S.

1993-01-01

A 2000 A class Nb 3 Sn persistent current switch has been successfully fabricated in the Toshiba R and D Center. The Nb tube processed conductor with Cu-10 wt.% Ni matrix has been developed for the switch in the Showa Electric Wire and Cable Co. Ltd. The magnetic instability which was observed in the previous 35 Ω Nb 3 Sn persistent current switch was improved in the present switch. The problem of quench current degradation and flux jump on magnetization, emerged in the previous switch, were confirmed to be solved. In the fast ramp, however, the switch degrades from the calculated results assuming the self field ac loss. In the Nb 3 Sn reaction process, Sn in the bronze diffuses into the Nb tube, which decreases the switch resistance. It was observed by a computer aided micro analysis (CMA) that Ni in the CuNi matrix precipitated on the Nb tube, which slightly reduced the switch resistance. (orig.)

Sensitive technique for detecting outer defect on tube with remote field eddy current testing

International Nuclear Information System (INIS)

Kobayashi, Noriyasu; Nagai, Satoshi; Ochiai, Makoto; Jimbo, Noboru; Komai, Masafumi

2008-01-01

In the remote field eddy current testing, we proposed the method of enhancing the magnetic flux density in the vicinity of an exciter coil by controlling the magnetic flux direction for increasing the sensitivity of detecting outer defects on a tube and used the flux guide made of a magnetic material for the method. The optimum structural shape of the flux guide was designed by the magnetic field analysis. On the experiment with the application of the flux guide, the magnetic flux density increased by 59% and the artificial defect detection signal became clear. We confirmed the proposed method was effective in a high sensitivity. (author)

Design of planar electron gun for UHF range, CW power inductive output tube

International Nuclear Information System (INIS)

Kaushik, Meenu; Joshi, L.M.

2015-01-01

Inductive Output Tube (lOT) is an amplifier which is now-a-days in demand for scientific applications. For every vacuum tube, electron gun is an important part and in fact considered as the heart of the tube. Hence, designing of this component is very crucial for efficient operation of the device throughout its lifetime. This paper is all about the electromagnetic (EM) design of planar electron gun of 40 kV, 3.5 A beam voltage and beam current respectively, for a 100 kW CW power lOT operating in UHF range. The design considerations and basic equations involved in its design are included in the paper. The gun structure has been optimized for getting the desired beam characteristics. The simulation results including the beam profile along with the beam current are shown using two commercial codes namely TRAK and MAGIC code. Planar shape of electron beam reduces space charge forces in the beam itself and consequently beam energy spread for a given current. The magnetic focusing of planar beam is easier comparative to spherical beam hence, this structure has been adopted for this particular device design. (author)

Automatic exposure control to reduce the dose in subsecond multislice spiral CT: phantom measurements and clinical results

International Nuclear Information System (INIS)

Greess, H.; Bautz, W.; Baum, U.; Wolf, H.; Suess, C.; Kalender, W.A.

2004-01-01

Purpose: To investigate the potential of dose reduction in multislice spiral CT (MSCT) with automatic exposure control. Materials and Methods: The study was performed on a Sensation 4 multislice scanner. This prototype implementation analyzed the distribution of the attenuation along the z-axis in the lateral and sagittal directions of the digital radiogram. Depending on this distribution of the attenuation, the tube current (mA) is defined for every tube rotation. In addition, the tube current was modulated during each tube rotation. First, a three step oval water phantom was measured to evaluate the potential of this method with respect to dose reduction and image quality. In a patient study (n=26), four different scan regions (shoulder, thorax, abdomen, pelvis) were examined and dose (mAs) and image quality evaluated in comparison to examinations with a standard protocol for these regions in adults and a weight-adjusted standard protocol in children. The image quality was classified in consensus as good, sufficient and poor image quality. Results: By adapting and modulating the tube current, we substantially reduced the variation of noise in one spiral scan and in one scan region of our patient collective. The dose (average mAs) was reduced by 31% to 66% in children (mean 44%) and between 35% and 64% in adults (mean 53%), depending on the scan region. The image quality was substantially improved in regions with high attenuation and did not suffer in low attenuation regions. Conclusion: The dose can be reduced substantially by an automatic exposure control including angular tube current modulation with the same or improved image quality. (orig.) [de

A comparison of tape-tying versus a tube-holding device for securing endotracheal tubes in adults.

Science.gov (United States)

Murdoch, E; Holdgate, A

2007-10-01

During the transfer of intubated patients, endotracheal tube security is paramount. This study aims to compare two methods of securing an endotracheal tube in adults: tying with a cloth tape versus the Thomas Endotracheal Tube Holder (Laerdal). A manikin-based study was performed using paramedics and critical care doctors (consultants and senior trainees) as participants. Each participant was asked to secure an endotracheal tube that had been placed within the trachea of a manikin a total of six times, the first three times using tied cloth tape and the last three times using a Thomas Endotracheal Tube Holder. Following each 'fixation' and after the participant had left the room, the security of the tube was tested by applying a fixed force laterally and to the right by dropping a 1.25 kg weight a distance of 50 cm. The amount of movement of the tube with respect to the teeth was measured and recorded in millimetres. Two-hundred-and-seventy tube fixations (135 tied vs. 135 tube holder) were performed by 45 participants. The degree of tube movement was significantly higher when the tube was secured with a tie compared with when the tube holder was used (median movement 22 mm vs. 4 mm, P tube holder device minimised tube movement in a manikin model when compared with conventional tape tying. The use of this device when transporting intubated patients may reduce the risk of tube displacement though further clinical studies are warranted.

Eddy Currents Inspection of CANDU Steam Generator Tubes using Zetec's ZR-1 Robot. Experience in Romania

International Nuclear Information System (INIS)

Scott Hower; Luiza Vladu; Adrian Nichisov; Mihai Cretu

2006-01-01

Full text of publication follows: The commercial operation of Unit 1 of Cernavoda NPP started on 2 December, 1996. The unit's reactor type is PHWR-CANDU 6 (electrical capacity 706 MWe), using natural uranium. The nuclear fuel is manufactured in Romania. The Cernavoda nuclear power plant has four CANDU - design steam generators that have been in service since 1996. The paper introduces the new ZR-1 Robot System for Inspection and Maintenance/Repair from Zetec that combines the newest state-of-the-art robotics technology with Zetec experience - based innovation to address the needs for inspection and repair of steam generators. The multipurpose ZR-1 can be easily installed to perform the necessary eddy current inspection and remain installed ready for follow-up maintenance and repair. It has superior technical performances and a modular three axis motion of arm that enables 100% coverage of tube sheet. Automated, repeatable, and precise positioning of tool heads ensures accurate delivery and reducing costly rework and reduces inspection time by 30%. The modular, light weight, and portable design permits easy assembly and disassembly through small openings and it reduces setup/tear down time by 30%. The first deployment of the new ZR-1 Robot was made in September 2004 at the Cernavoda NPP inspection outage. The unit's reactor type is PHWR-CANDU 6 (electrical capacity 706 MWe), using natural uranium; the nuclear fuel is manufactured in Romania. The Cernavoda nuclear power plant Unit 1 has four CANDU - design steam generators that have been in service since 1996. The paper presents also the Zetec's field experience and customer experience with this system. It describes the equipment setup in Cernavoda's steam generators mock-up, functional tests and calibration. Finally, provides details on the execution of the inspection, options for standardizing the inspection techniques and conclusions. (authors)

Preliminary research on eddy current bobbin quantitative test for heat exchange tube in nuclear power plant

Science.gov (United States)

Qi, Pan; Shao, Wenbin; Liao, Shusheng

2016-02-01

For quantitative defects detection research on heat transfer tube in nuclear power plants (NPP), two parts of work are carried out based on the crack as the main research objects. (1) Production optimization of calibration tube. Firstly, ASME, RSEM and homemade crack calibration tubes are applied to quantitatively analyze the defects depth on other designed crack test tubes, and then the judgment with quantitative results under crack calibration tube with more accuracy is given. Base on that, weight analysis of influence factors for crack depth quantitative test such as crack orientation, length, volume and so on can be undertaken, which will optimize manufacture technology of calibration tubes. (2) Quantitative optimization of crack depth. Neural network model with multi-calibration curve adopted to optimize natural crack test depth generated in in-service tubes shows preliminary ability to improve quantitative accuracy.

Characteristics of Pilger Die Materials for Nuclear Zirconium Alloy Tubes

International Nuclear Information System (INIS)

Park, Ki Bum; Kim, In Kyu; Park, Min Young; Kahng, Jong Yeol; Kim, Sun Doo

2011-01-01

KEPCO Nuclear Fuel Company's (KEPCO NF) tube manufacturing facility, Techno Special Alloy (TSA) Plant, has started cold pilgering operation since 2008. It is obvious that the cold pilgering process is one of the key processes controlling the quality and the characteristics of the tubes manufactured, i.e. nuclear zirconium alloy tube in KEPCO NF. Cold pilgering is a rolling process for forming metal tubes in which diameter and wall thickness are reduced in a number of forming steps, using ring dies at outside of the tube and a curved mandrel at inside to reduce tube cross sections by up to 90 percent. The OD size of tube is reduced by a pair of dies, and ID size and wall thickness is controlled simultaneously by mandrel. During the cold pilgering process, both tools are the critical components for providing qualified tube. Development of pilger die and mandrel has been a significant importance in the zirconium tube manufacturing and a major goal of KEPCO NF. The objective of this study is to evaluate the life time of pilger die during pilgering. Therefore, a comparison of the heat treatment and mechanical properties of between AISI 52100 and AISI H13 materials was made in this study

Steam generator tube failures

International Nuclear Information System (INIS)

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

Characterization of high-current, high-temperature superconductor current lead elements

International Nuclear Information System (INIS)

Niemann, R.C.; Evans, D.J.; Fisher, B.L.; Brockenborough, W.E.; Roberts, P.R.; Rodenbush, A.J.

1996-08-01

The refrigeration loads of current leads for superconducting magnets can be significantly reduced by using high-temperature superconductor (HTS) leads. An HTS conductor type that is well suited for this application is a laminated sintered stack of HTS powder-in-tube (PIT) tapes. The superconducting elements are normally characterized by their manufacturer by measuring critical currents at 77 K in self field. Additional characterization, which correlates electrical performance at 77 K and at lower temperatures with applied magnetic fields, provides the current lead designer and conductor element manufacturer with critical information. For HTS conductor elements comprising a laminated and sintered stack of Bi-2223 PIT tapes having an alloyed Ag sheath, this characterization uses variable applied fields and operating temperatures

THE TOPOLOGY OF CANONICAL FLUX TUBES IN FLARED JET GEOMETRY

Energy Technology Data Exchange (ETDEWEB)

Lavine, Eric Sander; You, Setthivoine, E-mail: Slavine2@uw.edu, E-mail: syou@aa.washington.edu [University of Washington, 4000 15th Street, NE Aeronautics and Astronautics 211 Guggenheim Hall, Box 352400, Seattle, WA 98195 (United States)

2017-01-20

Magnetized plasma jets are generally modeled as magnetic flux tubes filled with flowing plasma governed by magnetohydrodynamics (MHD). We outline here a more fundamental approach based on flux tubes of canonical vorticity, where canonical vorticity is defined as the circulation of the species’ canonical momentum. This approach extends the concept of magnetic flux tube evolution to include the effects of finite particle momentum and enables visualization of the topology of plasma jets in regimes beyond MHD. A flared, current-carrying magnetic flux tube in an ion-electron plasma with finite ion momentum is thus equivalent to either a pair of electron and ion flow flux tubes, a pair of electron and ion canonical momentum flux tubes, or a pair of electron and ion canonical vorticity flux tubes. We examine the morphology of all these flux tubes for increasing electrical currents, different radial current profiles, different electron Mach numbers, and a fixed, flared, axisymmetric magnetic geometry. Calculations of gauge-invariant relative canonical helicities track the evolution of magnetic, cross, and kinetic helicities in the system, and show that ion flow fields can unwind to compensate for an increasing magnetic twist. The results demonstrate that including a species’ finite momentum can result in a very long collimated canonical vorticity flux tube even if the magnetic flux tube is flared. With finite momentum, particle density gradients must be normal to canonical vorticities, not to magnetic fields, so observations of collimated astrophysical jets could be images of canonical vorticity flux tubes instead of magnetic flux tubes.

Fabrication of seamless calandria tubes

International Nuclear Information System (INIS)

Saibaba, N.; Phanibabu, C.; Bhaskara Rao, C.V.; Kalidas, R.; Ganguly, C.

2002-01-01

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

An experimental study of ECT for fin-type copper alloy tubes

International Nuclear Information System (INIS)

Lee, Hyung Joon; Lee, Jeong Soon; Sung, Je Joong; Park, Cheon Woong; Suh, Dong Man; Yu, Taek In

2002-01-01

Eddy current detecting probes with inner and encircling coils were designed for the fin-type tubes that have uneven outer and inner surface to enhance the efficiency of heat emission. As the uneven surface of them, it is difficult to detect flaws in the tubes by eddy current test. In this paper, standard and artificial specimens with flaws for the different types of the tubes were manufactured. Eddy current test was performed with the designed probes, which have inner and encircling coils, for the prepared specimens. From the signals of the eddy current detecting probes, the phase and amplitude variation were analyzed and the best conditions of the flaw detection for the tubes were found.

Development of a system for monitoring and diagnosis of steam generator tubes using artificial intelligence techniques on Eddy Current Test signals

International Nuclear Information System (INIS)

Mesquita, Roberto Navarro de; Ting, Daniel Kao Sun; Lopez, Luis A. Negro M.; Upadhyaya, Belle R.

2002-01-01

New classification and feature extraction methods for steam generator tube defects are being developed by IPEN/CNEN-SP in cooperation with UTK to improve a monitoring and diagnosis system for classification and characterization of steam generator tube defects using Eddy Current Testing (ECT) signals. The first methodology being developed uses a set of feature extraction methods applied to different tube defect type ECT signals and each obtained feature vector is projected into a bi-dimensional map obtained by a Self-Organizing Map neural network. This methodology allows an optimal feature extraction method selection for the defect type classification. Other approach is being developed using tubes with different manufactured defect types which are tested using MIZ-17ET equipment with 4 sets of probes (two different diameter). A fuzzy inference system will be used to build a knowledge base for these defects. These methodology and algorithms will be integrated into an automated diagnosis system being developed with UTK, which is designed to read both on-line acquired data, as well as stored data files. These commercial software tools are the ones usually utilized in nuclear power plants. (author)

Development of a system for monitoring and diagnosis of steam generator tubes using artificial intelligence techniques on Eddy Current Test signals

Energy Technology Data Exchange (ETDEWEB)

Mesquita, Roberto Navarro de [Instituto de Pesquisas Energeticas e Nucleares (IPEN), Sao Paulo, SP (Brazil). Centro de Monitoracao e Diagnostico]|[Sao Paulo Univ., SP (Brazil); Ting, Daniel Kao Sun [Instituto de Pesquisas Energeticas e Nucleares (IPEN), Sao Paulo, SP (Brazil). Centro de Monitoracao e Diagnostico; Cabral, Eduardo Lobo C. [Sao Paulo Univ., SP (Brazil); Lopez, Luis A. Negro M. [Faculdade de Engenharia Industrial, Sao Bernardo do Campo, SP (Brazil); Upadhyaya, Belle R. [Tennessee Univ., Knoxville, TN (United States)

2002-07-01

New classification and feature extraction methods for steam generator tube defects are being developed by IPEN/CNEN-SP in cooperation with UTK to improve a monitoring and diagnosis system for classification and characterization of steam generator tube defects using Eddy Current Testing (ECT) signals. The first methodology being developed uses a set of feature extraction methods applied to different tube defect type ECT signals and each obtained feature vector is projected into a bi-dimensional map obtained by a Self-Organizing Map neural network. This methodology allows an optimal feature extraction method selection for the defect type classification. Other approach is being developed using tubes with different manufactured defect types which are tested using MIZ-17ET equipment with 4 sets of probes (two different diameter). A fuzzy inference system will be used to build a knowledge base for these defects. These methodology and algorithms will be integrated into an automated diagnosis system being developed with UTK, which is designed to read both on-line acquired data, as well as stored data files. These commercial software tools are the ones usually utilized in nuclear power plants. (author)

Analysis of microwave amplifier and frequency multiplier tube with a multipactor electron gun

International Nuclear Information System (INIS)

Yokoo, Kuniyoshi; Ono, Shoichi; Tai, Dong-Zhe.

1983-01-01

The performance analysis was made for a multipactor microwave tube with the aim of realizing a microwave amplifier or a frequency multiplier tube with a multipactor cathode with high efficiency and high power. The possibility for producing the multipactor tube with high efficiency and high power was shown by using effectively the characteristics of the multipactor cathode which emits pulsed electron current with narrow band, synchronizing with high frequency period. As the operating conditions for the multipactor cathode, it was shown that the wide spacing of the cathode was needed for the operation in high operating power, and the narrow spacing was needed for the operation in high efficiency and for reducing power consumption. It was also shown that there were the best values of the high-frequency voltage for the cathode operation. The study by the simulation for the multipactor cathode and for the acceleration zone of electron current was also performed to examine the possible performance for a microwave amplifier and a frequency multiplier tube. For the use of the multipactor cathode with a spacing of 1 mm, the conversion efficiency for d. c. input power was 86, 56 and 31 % for the primary, the secondary and the tertiary harmonic wave amplifications, respectively. (Asami, T.)

Selected reading on introduction to pressure tube technology

International Nuclear Information System (INIS)

Causey, A.R.; Coleman, C.E.; Ells, C.E.

1981-10-01

Four lectures on pressure tube technology were presented at Sheridan Park, Ontario, on 1981 June 1. The titles were 'Pressure Tubes and Their Operational Environment', 'Fabrication, Inspection and Properties of Current Production Pressure Tubes', 'In-Reactor Deformation of Fuel Channels', and 'Potential Failure Modes in Pressure Tubes'. This report lists the references used in preparing the lectures. It is intended to provide a starting point in reading for people who need to become familiar with pressure tube technology but have little prior knowledge of the topic

Means and method for controlling the neutron output of a neutron generator tube

International Nuclear Information System (INIS)

Langford, O.M.; Peelman, H.E.

1980-01-01

A gas filled neutron tube in a nuclear well logging tool has a target an ion source voltage and a replenisher connected to ground. A negative high voltage is applied to the target by a power supply also providing a target current corresponding to the neutron output of the neutron generator tube. A constant current source provides a constant current. A network receiving the target current and the constant current provides a portion of the constant current as a replenisher current which is applied to the replenisher in a neutron generating tube. The network controls the magnitude of the replenisher current in accordance with the target current so as to control the neutron output of the neutron generating tube. (auth)

In service inspection for steam generator tubes

International Nuclear Information System (INIS)

Comby, R.; Eyrolles, Ph.

1988-01-01

In this paper the authors show the means putting in place for examination of steam generators tubes. These means (eddy current probes, ultrasonic testing) associated with a knowledge on degradation phenomena allow mapping controlled tubes and limiting undesirable obturations [fr

Effect of the surface film electric resistance on eddy current detectability of surface cracks in Alloy 600 tubes

International Nuclear Information System (INIS)

Saario, T.; Paine, J.P.N.

1995-01-01

The most widely used technique for NDE of steam generator tubing is eddy current. This technique can reliably detect cracks grown in sodium hydroxide environment only at depths greater than 50% through wall. However, cracking caused by thiosulphate solutions have been detected and sized at shallower depths. The disparity has been proposed to be caused by the different electric resistance of the crack wall surface films and corrosion products in the cracks formed in different environments. This work was undertaken to clarify the role of surface film electric resistance on the disparity found in eddy current detectability of surface cracks in alloy 600 tubes. The proposed model explaining the above mentioned disparity is the following. The detectability of tightly closed cracks by the eddy current technique depends on the electric resistance of the surface films of the crack walls. The nature and resistance of the films which form on the crack walls during operation depends on the composition of the solution inside the crack and close to the crack location. During cooling down of the steam generator, because of contraction and loss of internal pressurization, the cracks are rather tightly closed so that exchange of electrolyte and thus changes in the film properties become difficult. As a result, the surface condition prevailing at high temperature is preserved. If the environment is such that the films formed on the crack walls under operating conditions have low electric resistance, eddy current technique will fail to indicate these cracks or will underestimate the size of these cracks. However, if the electric resistance of the films is high, a tightly closed crack will resemble an open crack and will be easily indicated and correctly sized by eddy current technique

X-ray tube technology update

International Nuclear Information System (INIS)

Rehani, M.M.

1997-01-01

During the 100 years since the discovery of x-rays, the x-ray tube has undergone significant improvements to meet the demand of shorter exposure time and frequent exposures as in angiography. This has been achieved by multiple focal spots, rotating anodes, design consideration of the anode and the tube assembly. While physical improvements have resulted in improved performance, the principle has remained the same, as also has the problem of massive heat generation which consumes almost 99% of the energy. This article traces the history of tubes and current perspectives. (author). 3 refs., 3 figs., 2 tabs

Computed tomography: influence of varying tube current on patient dose and correctness of effective dose calculations; Computertomografie: Einfluss des variablen Roehrenstroms auf die Patientendosis und die Genauigkeit von Berechnungen der effektiven Dosis

Energy Technology Data Exchange (ETDEWEB)

Hietschold, V. [Inst. und Poliklinik fuer Radiologische Diagnostik, Universitaetsklinikum Carl-Gustav-Carus der TU Dresden (Germany); Koch, A.; Laniado, M.; Abolmaali, N.D. [OncoRay, Molecular Imaging, TU Dresden (Germany)

2008-05-15

Purpose: determination of the influence of tube currents varying during a CT scan on organ doses and on the effective dose as a function of patient constitution. Evaluation of the accuracy of effective dose calculations based on summarizing parameters (effective mAs, dose length product [DLP]) compared to calculations based on slice-specific tube currents. Materials and methods: investigation of the CT datasets of 806 patients acquired from the skull base to the proximal thigh with respect to the body mass index (BMI). The effective dose was calculated by means of slice-specific as well as region-specific conversion factors. Results: dose optimization by means of variable tube current resulted in a reduction of the gonad dose in patients with BMI {<=} 20.. 21 kg/m{sup 2} and of the effective dose in patients with BMI {<=} 26 kg/m{sup 2}. Effective dose values calculated with the DLP for 90% of the patients are within an interval of {+-} 20% of the values calculated using slice-specific tube currents. Conclusion: if tube current optimization during the CT scan was applied, for the scan region under investigation, at a BMI already below the German mean value, an increased effective dose was observed. Calculations of the effective dose on the basis of summarizing values such as DLP or effective mAs are of sufficient accuracy. (orig.)

Implementation status of performance demonstration program for steam generator tubing analysts in Korea

International Nuclear Information System (INIS)

Cho, Chan Hee; Lee, Hee Jong; Yoo, Hyun Ju; Nam, Min Woo; Hong, Sung Yull

2013-01-01

Some essential components in nuclear power plants are periodically inspected using non destructive examinations, for example ultrasonic, eddy current and radiographic examinations, in order to determine their integrity. These components include nuclear power plant items such as vessels, containments, piping systems, pumps, valves, tubes and core support structure. Steam generator tubes have an important safety role because they constitute one of the primary barriers between the radioactive and non radioactive sides of the nuclear power plant. There is potential that if a tube bursts while a plant is operating, radioactivity from the primary coolant system could escape directly to the atmosphere. Therefore, in service inspections are critical in maintaining steam generator tube integrity. In general, the eddy current testing is widely used for the inspection of steam generator tubes due tube integrity. In general, the eddy current testing is widely used for the inspection of steam generator tubes due to its high inspection speed and flaw detectability on non magnetic tubes. However, it is not easy to analyze correctly eddy current signals because they are influenced by many factors. Therefore, the performance of eddy current data analysts for steam generator tubing should be demonstrated comprehensively. In Korea, the performance of steam generator tubing analysts has been demonstrated using the Qualified Data Analyst program. This paper describes the performance demonstration program for steam generator tubing analysts and its implementation results in Korea. The pass rate of domestic analysts for this program was 71.4%

Implementation status of performance demonstration program for steam generator tubing analysts in Korea

Energy Technology Data Exchange (ETDEWEB)

Cho, Chan Hee; Lee, Hee Jong; Yoo, Hyun Ju; Nam, Min Woo [KHNP Central Research Institute, Daejeon (Korea, Republic of); Hong, Sung Yull [Yeungnam Univ., Gyeongsan (Korea, Republic of)

2013-02-15

Some essential components in nuclear power plants are periodically inspected using non destructive examinations, for example ultrasonic, eddy current and radiographic examinations, in order to determine their integrity. These components include nuclear power plant items such as vessels, containments, piping systems, pumps, valves, tubes and core support structure. Steam generator tubes have an important safety role because they constitute one of the primary barriers between the radioactive and non radioactive sides of the nuclear power plant. There is potential that if a tube bursts while a plant is operating, radioactivity from the primary coolant system could escape directly to the atmosphere. Therefore, in service inspections are critical in maintaining steam generator tube integrity. In general, the eddy current testing is widely used for the inspection of steam generator tubes due tube integrity. In general, the eddy current testing is widely used for the inspection of steam generator tubes due to its high inspection speed and flaw detectability on non magnetic tubes. However, it is not easy to analyze correctly eddy current signals because they are influenced by many factors. Therefore, the performance of eddy current data analysts for steam generator tubing should be demonstrated comprehensively. In Korea, the performance of steam generator tubing analysts has been demonstrated using the Qualified Data Analyst program. This paper describes the performance demonstration program for steam generator tubing analysts and its implementation results in Korea. The pass rate of domestic analysts for this program was 71.4%.

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

International Nuclear Information System (INIS)

Garcia, Gabe V.

2005-01-01

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

Contrastive Analysis and Research on Negative Pressure Beam Tube System and Positive Pressure Beam Tube System for Mine Use

Science.gov (United States)

Wang, Xinyi; Shen, Jialong; Liu, Xinbo

2018-01-01

Against the technical defects of universally applicable beam tube monitoring system at present, such as air suction in the beam tube, line clogging, long sampling time, etc., the paper analyzes the current situation of the spontaneous combustion fire disaster forecast of mine in our country and these defects one by one. On this basis, the paper proposes a research thought that improving the positive pressure beam tube so as to substitute the negative pressure beam tube. Then, the paper introduces the beam tube monitoring system based on positive pressure technology through theoretical analysis and experiment. In the comparison with negative pressure beam tube, the paper concludes the advantage of the new system and draws the conclusion that the positive pressure beam tube is superior to the negative pressure beam tube system both in test result and test time. At last, the paper proposes prospect of the beam tube monitoring system based on positive pressure technology.

Jose Cabrera (Zorita) tube examination

International Nuclear Information System (INIS)

Kuchirka, P.J.

1986-01-01

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

Identifying Measures Used for Assessing Quality of YouTube Videos with Patient Health Information: A Review of Current Literature.

Science.gov (United States)

Gabarron, Elia; Fernandez-Luque, Luis; Armayones, Manuel; Lau, Annie Ys

2013-02-28

Recent publications on YouTube have advocated its potential for patient education. However, a reliable description of what could be considered quality information for patient education on YouTube is missing. To identify topics associated with the concept of quality information for patient education on YouTube in the scientific literature. A literature review was performed in MEDLINE, ISI Web of Knowledge, Scopus, and PsychINFO. Abstract selection was first conducted by two independent reviewers; discrepancies were discussed in a second abstract review with two additional independent reviewers. Full text of selected papers were analyzed looking for concepts, definitions, and topics used by its authors that focused on the quality of information on YouTube for patient education. In total, 456 abstracts were extracted and 13 papers meeting eligibility criteria were analyzed. Concepts identified related to quality of information for patient education are categorized as expert-driven, popularity-driven, or heuristic-driven measures. These include (in descending order): (1) quality of content in 10/13 (77%), (2) view count in 9/13 (69%), (3) health professional opinion in 8/13 (62%), (4) adequate length or duration in 6/13 (46%), (5) public ratings in 5/13 (39%), (6) adequate title, tags, and description in 5/13 (39%), (7) good description or a comprehensive narrative in 4/13 (31%), (8) evidence-based practices included in video in 4/13 (31%), (9) suitability as a teaching tool in 4/13 (31%), (10) technical quality in 4/13 (31%), (11) credentials provided in video in 4/13 (31%), (12) enough amount of content to identify its objective in 3/13 (23%), and (13) viewership share in 2/13 (15%). Our review confirms that the current topics linked to quality of information for patient education on YouTube are unclear and not standardized. Although expert-driven, popularity-driven, or heuristic-driven measures are used as proxies to estimate the quality of video information

Non-uniform tube representation of proteins

DEFF Research Database (Denmark)

Hansen, Mikael Sonne

Treating the full protein structure is often neither computationally nor physically possible. Instead one is forced to consider various reduced models capturing the properties of interest. Previous work have used tubular neighborhoods of the C-alpha backbone. However, assigning a unique radius...... might not correctly capture volume exclusion - of crucial importance when trying to understand a proteins $3$d-structure. We propose a new reduced model treating the protein as a non-uniform tube with a radius reflecting the positions of atoms. The tube representation is well suited considering X......-ray crystallographic resolution ~ 3Å while a varying radius accounts for the different sizes of side chains. Such a non-uniform tube better capture the protein geometry and has numerous applications in structural/computational biology from the classification of protein structures to sequence-structure prediction....

Dynamics of explosively imploded pressurized tubes

Science.gov (United States)

Szirti, Daniel; Loiseau, Jason; Higgins, Andrew; Tanguay, Vincent

2011-04-01

The detonation of an explosive layer surrounding a pressurized thin-walled tube causes the formation of a virtual piston that drives a precursor shock wave ahead of the detonation, generating very high temperatures and pressures in the gas contained within the tube. Such a device can be used as the driver for a high energy density shock tube or hypervelocity gas gun. The dynamics of the precursor shock wave were investigated for different tube sizes and initial fill pressures. Shock velocity and standoff distance were found to decrease with increasing fill pressure, mainly due to radial expansion of the tube. Adding a tamper can reduce this effect, but may increase jetting. A simple analytical model based on acoustic wave interactions was developed to calculate pump tube expansion and the resulting effect on the shock velocity and standoff distance. Results from this model agree quite well with experimental data.

Effect of Localizer Radiography Projection on Organ Dose at Chest CT with Automatic Tube Current Modulation.

Science.gov (United States)

Saltybaeva, Natalia; Krauss, Andreas; Alkadhi, Hatem

2017-03-01

Purpose To calculate the effect of localizer radiography projections to the total radiation dose, including both the dose from localizer radiography and that from subsequent chest computed tomography (CT) with tube current modulation (TCM). Materials and Methods An anthropomorphic phantom was scanned with 192-section CT without and with differently sized breast attachments. Chest CT with TCM was performed after one localizer radiographic examination with anteroposterior (AP) or posteroanterior (PA) projections. Dose distributions were obtained by means of Monte Carlo simulations based on acquired CT data. For Monte Carlo simulations of localizer radiography, the tube position was fixed at 0° and 180°; for chest CT, a spiral trajectory with TCM was used. The effect of tube start angles on dose distribution was investigated with Monte Carlo simulations by using TCM curves with fixed start angles (0°, 90°, and 180°). Total doses for lungs, heart, and breast were calculated as the sum of the dose from localizer radiography and CT. Image noise was defined as the standard deviation of attenuation measured in 14 circular regions of interest. The Wilcoxon signed rank test, paired t test, and Friedman analysis of variance were conducted to evaluate differences in noise, TCM curves, and organ doses, respectively. Results Organ doses from localizer radiography were lower when using a PA instead of an AP projection (P = .005). The use of a PA projection resulted in higher TCM values for chest CT (P chest CT. © RSNA, 2016 Online supplemental material is available for this article.

Integrating YouTube into the nursing curriculum.

Science.gov (United States)

Sharoff, Leighsa

2011-08-17

Nurse educators need to be innovative, stimulating, and engaging as they teach future nursing professionals. The use of YouTube in nursing education classes provides an easy, innovative, and user-friendly way to engage today's nursing students. YouTube presentations can be easily adapted into nursing courses at any level, be it a fundamentals course for undergraduate students or a theoretical foundations course for graduate students. In this article I will provide information to help educators effectively integrate YouTube into their course offerings. I will start by reviewing the phenomenon of social networking. Next I will discuss challenges and strategies related to YouTube learning experiences, after which I will share some of the legal considerations in using YouTube. I will conclude by describing how to engage students via YouTube and current research related to YouTube.

Convolution-based estimation of organ dose in tube current modulated CT

Science.gov (United States)

Tian, Xiaoyu; Segars, W. Paul; Dixon, Robert L.; Samei, Ehsan

2016-05-01

Estimating organ dose for clinical patients requires accurate modeling of the patient anatomy and the dose field of the CT exam. The modeling of patient anatomy can be achieved using a library of representative computational phantoms (Samei et al 2014 Pediatr. Radiol. 44 460-7). The modeling of the dose field can be challenging for CT exams performed with a tube current modulation (TCM) technique. The purpose of this work was to effectively model the dose field for TCM exams using a convolution-based method. A framework was further proposed for prospective and retrospective organ dose estimation in clinical practice. The study included 60 adult patients (age range: 18-70 years, weight range: 60-180 kg). Patient-specific computational phantoms were generated based on patient CT image datasets. A previously validated Monte Carlo simulation program was used to model a clinical CT scanner (SOMATOM Definition Flash, Siemens Healthcare, Forchheim, Germany). A practical strategy was developed to achieve real-time organ dose estimation for a given clinical patient. CTDIvol-normalized organ dose coefficients ({{h}\\text{Organ}} ) under constant tube current were estimated and modeled as a function of patient size. Each clinical patient in the library was optimally matched to another computational phantom to obtain a representation of organ location/distribution. The patient organ distribution was convolved with a dose distribution profile to generate {{≤ft(\\text{CTD}{{\\text{I}}\\text{vol}}\\right)}\\text{organ, \\text{convolution}}} values that quantified the regional dose field for each organ. The organ dose was estimated by multiplying {{≤ft(\\text{CTD}{{\\text{I}}\\text{vol}}\\right)}\\text{organ, \\text{convolution}}} with the organ dose coefficients ({{h}\\text{Organ}} ). To validate the accuracy of this dose estimation technique, the organ dose of the original clinical patient was estimated using Monte Carlo program with TCM profiles explicitly modeled. The

Contribution to perfecting eddy current testing of steam generator tubes of sodium cooled breeders: description of the Monacault loop for the study of sodium deposit influence

International Nuclear Information System (INIS)

Lapicore, A.; Lemarquis, J.C.; Oberlin, C.; Pigeon, M.

1981-12-01

In the event of sodium-water reaction in the steam generator of a sodium cooled breeder reactor, it is essential to be able to monitor the local loss of thickness of the tubes located in the reaction area. A method for monitoring the tubes by an eddy current probe is being developed for Super Phenix. The sodium deposits on the outer wall of the tubes, as well as their prolonged contact with high temperature sodium are likely to bring about a change in the signals picked up. A test loop, Monacault, has been built in order to clarify the importance of these parameters (effect of sodium deposits, reproducibility of the wetting at different temperatures). It includes three test cells containing the sample tubes having a total of 61 standard defects to be tested. The first results on the wetting of tubes are given and discussed [fr

Signal to noise ratio enhancement for Eddy Current testing of steam generator tubes in PWR's

International Nuclear Information System (INIS)

Georgel, B.

1985-01-01

Noise reduction is a compulsory task when we try to recognize and characterize flaws. The signals we deal with come from Eddy Current testings of steam generator steel tubes. We point out the need for a spectral invariant in digital spectral analysis of 2 components signals. We make clear the pros and cons of classical passband filtering and suggest the use of a new noise cancellation method first discussed by Moriwaki and Tlusty. We generalize this tricky technique and prove it is a very special case of the well-known Wiener filter. In that sense the M-T method is shown to be optimal. 6 refs

Improving accuracy of ET measurement of LISS nozzle to calandria tube clearance

International Nuclear Information System (INIS)

Craig, S.T.; Krause, T.W.; Schankula, J.J.

2006-01-01

The AECL Fuel Channel Inspection System (AFCIS) has been used in an in-reactor field trial to successfully measure the clearance between Liquid Injection Shutdown System (LISS) nozzles and calandria tubes. Each measurement over the full length of a channel added only 15 minutes to the on-channel inspection time. No changes were required to the inspection heads. The only equipment changes made were the addition of a Remote Field Eddy Current (RFEC) module to the eddy current instrument, and minor wiring changes, at the instrument, to achieve a RFEC configuration. With the experience gained from the field trial, factors potentially limiting accuracy were identified. These, and other factors, were investigated and are discussed herein. The RFEC probe is delivered inside the pressure tube. Magnetic fields from the RFEC probe extend through the conducting walls of the pressure tube and calandria tube to interact with the LISS nozzle. Data acquired during the field trial showed the LISS nozzle signal is distinct and the signal-to-noise ratio is very favourable. Nevertheless, comparison of the RFEC measurements to a visual examination, made during the same outage, had the RFEC method underestimating the clearance by 2.5 mm on average. By way of laboratory tests, the following factors were investigated as potential sources of error: resistivity and geometry of LISS nozzle reference/calibration pieces, pressure-tube wall thickness, diameter and resistivity variations, pressure-tube to calandria-tube gap, and radial offsets of the probe within the pressure-tube. The sensitivity to these various noise sources was established. A model, based on fundamental electromagnetic principles, was developed and was used to normalize the effects of LISS nozzle conductivity and geometry. This enabled compensation for various sources of error, and made it possible to produce a correction factor for the field trial data, reducing the average difference from the visual inspection of LISS

SPIRAL COUNTER-CURRENT CHROMATOGRAPHY OF SMALL MOLECULES, PEPTIDES AND PROTEINS USING THE SPIRAL TUBING SUPPORT ROTOR

OpenAIRE

Knight, Martha; Finn, Thomas M.; Zehmer, John; Clayton, Adam; Pilon, Aprile

2011-01-01

An important advance in countercurrent chromatography (CCC) carried out in open flow-tubing coils, rotated in planetary centrifuges, is the new design to spread out the tubing in spirals. More spacing between the tubing was found to significantly increase the stationary phase retention, such that now all types of two-phase solvent systems can be used for liquid-liquid partition chromatography in the J-type planetary centrifuges. A spiral tubing support (STS) frame with circular channels was c...

Mechanics of neurulation: From classical to current perspectives on the physical mechanics that shape, fold, and form the neural tube.

Science.gov (United States)

Vijayraghavan, Deepthi S; Davidson, Lance A

2017-01-30

Neural tube defects arise from mechanical failures in the process of neurulation. At the most fundamental level, formation of the neural tube relies on coordinated, complex tissue movements that mechanically transform the flat neural epithelium into a lumenized epithelial tube (Davidson, 2012). The nature of this mechanical transformation has mystified embryologists, geneticists, and clinicians for more than 100 years. Early embryologists pondered the physical mechanisms that guide this transformation. Detailed observations of cell and tissue movements as well as experimental embryological manipulations allowed researchers to generate and test elementary hypotheses of the intrinsic and extrinsic forces acting on the neural tissue. Current research has turned toward understanding the molecular mechanisms underlying neurulation. Genetic and molecular perturbation have identified a multitude of subcellular components that correlate with cell behaviors and tissue movements during neural tube formation. In this review, we focus on methods and conceptual frameworks that have been applied to the study of amphibian neurulation that can be used to determine how molecular and physical mechanisms are integrated and responsible for neurulation. We will describe how qualitative descriptions and quantitative measurements of strain, force generation, and tissue material properties as well as simulations can be used to understand how embryos use morphogenetic programs to drive neurulation. Birth Defects Research 109:153-168, 2017. © 2016 Wiley Periodicals, Inc. © 2016 Wiley Periodicals, Inc.

Influence of Tube Current Settings on Diagnostic Detection of Root Fractures Using Cone-beam Computed Tomography: An In Vitro Study.

Science.gov (United States)

Tangari-Meira, Ricardo; Vancetto, José Ricardo; Dovigo, Lívia Nordi; Tosoni, Guilherme Monteiro

2017-10-01

This study assessed the influence of tube current settings (milliamperes [mA]) on the diagnostic detection of root fractures (RFs) using cone-beam computed tomographic (CBCT) imaging. Sixty-eight human anterior and posterior teeth were submitted to root canal preparation, and 34 root canals were filled. The teeth were divided into 2 groups: the control group and the fractured group. RFs were induced using a universal mechanical testing machine; afterward, the teeth were placed in a phantom. Images were acquired using a Scanora 3DX unit (Soredex, Tuusula, Finland) with 5 different mA settings: 4.0, 5.0, 6.3, 8.0, and 10.0. Two examiners (E1 and E2) classified the images according to a 5-point confidence scale. Intra- and interexaminer reproducibility was assessed using the kappa statistic; diagnostic performance was assessed using the area under the receiver operating characteristic curve (AUROC). Intra- and interexaminer reproducibility showed substantial (κE1 = 0.791 and κE2 = 0.695) and moderate (κE1 × E2 = 0.545) agreement, respectively. AUROC was significantly higher (P ≤ .0389) at 8.0 and 10.0 mA and showed no statistical difference between the 2 tube current settings. Tube current has a significant influence on the diagnostic detection of RFs in CBCT images. Despite the acceptable diagnosis of RFs using 4.0 and 5.0 mA, those settings had lower discrimination abilities when compared with settings of 8.0 and 10.0 mA. Copyright © 2017 American Association of Endodontists. Published by Elsevier Inc. All rights reserved.

Damping in heat exchanger tube bundles. A review

International Nuclear Information System (INIS)

Iqbal, Qamar; Khushnood, Shahab; Ghalban, Ali Roheim El; Sheikh, Nadeem Ahmed; Malik, Muhammad Afzaal; Arastu, Asif

2007-01-01

Damping is a major concern in the design and operation of tube bundles with loosely supported tubes in baffles for process shell and tube heat exchangers and steam generators which are used in nuclear, process and power generation industries. System damping has a strong influence on the amplitude of vibration. Damping depends upon the mechanical properties of the tube material, geometry of intermediate supports and the physical properties of shell-side fluid. Type of tube motion, number of supports, tube frequency, vibration amplitude, tube mass or diameter, side loads, support thickness, higher modes, shell-side temperature etc., affect damping in tube bundles. The importance of damping is further highlighted due to current trend of larger exchangers with increased shell-side velocities in modern units. Various damping mechanisms have been identified (Friction damping, Viscous damping, Squeeze film damping, Support damping. Two-Phase damping, and very recent-Thermal damping), which affect the performance of process exchangers and steam generators with respect to flow induced vibration design, including standard design guidelines. Damping in two-phase flow is very complex and highly void fraction, and flow-regime dependent. The current paper focuses on the various known damping mechanisms subjected to both single and two-phase cross-flow in process heat exchangers and steam generators and formulates the design guidelines for safer design. (author)

Externally fired gas turbine cycles with high temperature heat exchangers utilising Fe-based ODS alloy tubing

International Nuclear Information System (INIS)

Olsson, F.; Svensson, S.-A.; Duncan, R.

2001-01-01

This work is part of the BRITE / EuRAM Project 'Development of Torsional Grain Structures to Improve Biaxial Creep Performance of Fe-based ODS Alloy Tubing for Biomass Power Plant'. The main goal of this project is to heat exchanger tubes working at 1100 o C and above. The paper deals with design implications of a biomass power plant, using an indirectly fired gas turbine with a high temperature heat exchanger containing Fe-based ODS alloy tubing. In the current heat exchanger design, ODS alloy tubing is used in a radiant section, using a bayonet type tube arrangement. This enables the use of straight sections of ODS tubing and reduces the amount of material required. In order to assess the potential of the power plant system, thermodynamic calculations have been conducted. Both co-generation and condensing applications are studied and results so far indicate that the electrical efficiency is high, compared to values reached by conventional steam cycle power plants of the same size (approx. 5 MW e ). (author)

Patient identification and tube labelling

DEFF Research Database (Denmark)

van Dongen-Lases, Edmée C; Cornes, Michael P; Grankvist, Kjell

2016-01-01

of phlebotomy procedures with the CLSI H3-A6 guideline was unacceptably low, and that patient identification and tube labelling are amongst the most critical steps in need of immediate attention and improvement. The process of patient identification and tube labelling is an essential safety barrier to prevent...... patient identity mix-up. Therefore, the EFLM Working Group aims to encourage and support worldwide harmonisation of patient identification and tube labelling procedures in order to reduce the risk of preanalytical errors and improve patient safety. With this Position paper we wish to raise awareness...... and provide recommendations for proper patient and sample identification procedures....

Heat Exchanger Tube Inspection of Nuclear Power Plants using IRIS Technique

International Nuclear Information System (INIS)

Yoon, Byung Sik; Yang, Seung Han; Song, Seok Yoon; Kim, Yong Sik; Lee, Hee Jong

2005-01-01

Inspection of heat exchange tubing include steam generator of nuclear power plant mostly performed with eddy current method. Recently, various inspection technique is available such as remote field eddy current, flux leakage and ultrasonic methods. Each of these techniques has its merits and limitations. Electromagnetic techniques are very useful to locate areas of concern but sizing is hard because of the difficult interpretation of an electric signature. On the other hand, ultrasonic methods are very accurate in measuring wall loss damage, and are reliable for detecting cracks. Additionally ultrasound methods is not affected by support plates or tube sheets and variation of electrical conductivity or permeability. Ultrasound data is also easier to analyze since the data displayed is generally the remaining wall thickness. It should be emphasized that ultrasound is an important tool for sizing defects in tubing. In addition, it can be used in situations where eddy current or remote field eddy current is not reliable, or as a flaw assessment tool to supplement the electromagnetic data. The need to develop specialized ultrasonic tools for tubing inspection was necessary considering the limitations of electromagnetic techniques to some common inspection problems. These problems the sizing of wall loss in carbon steel tubes near the tube sheet or support plate, sizing internal erosion damage, and crack detection. This paper will present an IRIS(Internal Rotating Inspection System) ultrasonic tube inspection technique for heat exchanger tubing in nuclear power plant and verify inspection reliability for artificial flaw embedded to condenser tube

Numerical simulation of tubes-in-tube heat exchanger in a mixed refrigerant Joule-Thomson cryocooler

Science.gov (United States)

Damle, R. M.; Ardhapurkar, P. M.; Atrey, M. D.

2017-02-01

Mixed refrigerant Joule-Thomson (MRJT) cryocoolers can produce cryogenic temperatures with high efficiency and low operating pressures. As compared to the high system pressures of around 150-200 bar with nitrogen, the operational pressures with non-azeotropic mixtures (e.g., nitrogen-hydrocarbons) come down to 10-25 bar. With mixtures, the heat transfer in the recuperative heat exchanger takes place in the two-phase region. The simultaneous boiling and condensation of the cold and hot gas streams lead to higher heat transfer coefficients as compared to single phase heat exchange. The two-phase heat transfer in the recuperative heat exchanger drastically affects the performance of a MRJT cryocooler. In this work, a previously reported numerical model for a simple tube-in-tube heat exchanger is extended to a multi tubes-in-tube heat exchanger with a transient formulation. Additionally, the J-T expansion process is also considered to simulate the cooling process of the heat exchanger from ambient temperature conditions. A tubes-in-tube heat exchanger offers more heat transfer area per unit volume resulting in a compact design. Also, the division of flow in multiple tubes reduces the pressure drop in the heat exchanger. Simulations with different mixtures of nitrogen-hydrocarbons are carried out and the numerical results are compared with the experimental data.

A simple tool for tubing modification to improve spiral high-speed counter-current chromatography for protein purification.

Science.gov (United States)

Ito, Yoichiro; Ma, Xiaofeng; Clary, Robert

2016-01-01

A simple tool is introduced which can modify the shape of tubing to enhance the partition efficiency in high-speed countercurrent chromatography. It consists of a pair of interlocking identical gears, each coaxially holding a pressing wheel to intermittently compress plastic tubing in 0 - 10 mm length at every 1 cm interval. The performance of the processed tubing is examined in protein separation with 1.6 mm ID PTFE tubing intermittently pressed in 3 mm and 10 mm width both at 10 mm intervals at various flow rates and revolution speeds. A series of experiments was performed with a polymer phase system composed of polyethylene glycol and dibasic potassium phosphate each at 12.5% (w/w) in deionized water using three protein samples. Overall results clearly demonstrate that the compressed tubing can yield substantially higher peak resolution than the non-processed tubing. The simple tubing modifier is very useful for separation of proteins with high-speed countercurrent chromatography.

Hypoglossal-facial anastomosis (HFA) over a 10 mm gap bridged by a Y-tube-conduit enhances neurite regrowth and reduces collateral axonal branching at the lesion site.

Science.gov (United States)

Ozsoy, Umut; Demirel, Bahadir Murat; Hizay, Arzu; Ozsoy, Ozlem; Ankerne, Janina; Angelova, Srebrina; Sarikcioglu, Levent; Ucar, Yasar; Angelov, Doychin N

2011-01-01

The outcome of severe peripheral nerve injuries requiring surgical repair (transection and suture) is usually poor. Recent work suggests that direct suture of nerves increases collagen production and provides unfavourable conditions for a proper axonal regrowth. We tested whether entubulation of the hypoglossal nerve into a Y-tube conduit connecting it with the zygomatic and buccal facial nerve branches would improve axonal pathfinding at the lesion site, quality of muscle reinnervation and recovery of vibrissal whisking. For hypoglossal-facial anastomosis (HFA) over a Y-tube (HFA-Y-tube) the proximal stump of the hypoglossal nerve was entubulated and sutured into the long arm of a Y-tube (isogeneic abdominal aorta with its bifurcation). The zygomatic and buccal facial branches were entubulated and sutured to the short arms of the Y-tube. Restoration of vibrissal motor performance, degree of collateral axonal branching at the lesion site and quality of neuro-muscular junction (NMJ) reinnervation were compared to animals receiving HFA-Coaptation (no entubulation) after 4 months. HFA-Y-tube reduced collateral axonal branching. However it failed to reduce the proportion of polyinnervated NMJ and did not improve functional outcome when compared to HFA-Coaptation. Elimination of compression by tightly opposed nerve fragments improved axonal pathfinding. However, biometric analysis of vibrissae movements did not show positive effects suggesting that polyneuronal reinnervation - rather than collateral branching - may be the critical limiting factor. Since polyinnervation of muscle fibers is activity-dependent and can be manipulated, the present findings raise hopes that clinically feasible and effective therapies after HFA could be soon designed and tested.

Thermal issues associated with the HVAC and lighting systems influences on the performance of the national ignition facility beam transport tubes

International Nuclear Information System (INIS)

Bernardin, J.D.; Parietti, L.; Martin, R.A.

1998-01-01

This report summarizes an investigation of the thermal issues related to the National Ignition Facility. In particular, the influences of the HVAC system and lighting fixtures on the operational performance of the laser guide beam tubes are reviewed and discussed. An analytical model of the oscillating HVAC air temperatures in the NIF switchyard and target bay will cause significant amounts of beam distortion. However, these negative effects can be drastically reduced by adding thermal insulation to the outside of the beam tubes. A computational fluid dynamics model and an analytical investigation found that the light-fixture to beam-tube separation distance must be on the order of 5.7 m (18.7 ft) to maintain acceptable beam operating performance in the current NIF design. By reducing the fluorescent light fixture power by 33% this separation distance can be reduced to 3.5 m (11.5 ft). If in addition, thermal insulation with a reflective aluminum foil covering is added to the outside of the beam tubes, the separation distance can be reduced further to 1.6m (5.2 ft). A 1.27 cm (0.5 in.) rigid foam insulation sheet with aluminum foil covering will provide adequate insulation for the beam tubes in the NIF switchyards and target bay. The material cost for this amount of insulation would be roughly $30,000

Analysis of the State of Steam Generator Tubes

International Nuclear Information System (INIS)

Bergunker, Olga

2008-01-01

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)

Development of a light weighted mobile robot for SG tube inspection in NPP

International Nuclear Information System (INIS)

Seo, Yong Chil; Jeong, Kyung Min; Shin, Hochul; Gweng, Jung Ju; Lee, Sung Uk; Jeong, Seung Ho; Choi, Young Soo; Kim, Seung Ho; Shin, Chun Sup; Park, Ki Tae

2012-01-01

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

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.

Comparison of standardized uptake values measured on F-NaF PET/CT scans using three different tube current intensities.

Science.gov (United States)

Valadares, Agnes Araujo; Duarte, Paulo Schiavom; Woellner, Eduardo Bechtloff; Coura-Filho, George Barberio; Sapienza, Marcelo Tatit; Buchpiguel, Carlos Alberto

2015-01-01

To analyze standardized uptake values (SUVs) using three different tube current intensities for attenuation correction on (18)FNaF PET/CT scans. A total of 254 (18)F-NaF PET/CT studies were analyzed using 10, 20 and 30 mAs. The SUVs were calculated in volumes of interest (VOIs) drawn on three skeletal regions, namely, right proximal humeral diaphysis (RH), right proximal femoral diaphysis (RF), and first lumbar vertebra (LV1) in a total of 712 VOIs. The analyses covered 675 regions classified as normal (236 RH, 232 RF, and 207 LV1). Mean SUV for each skeletal region was 3.8, 5.4 and 14.4 for RH, RF, and LV1, respectively. As the studies were grouped according to mAs value, the mean SUV values were 3.8, 3.9 and 3.7 for 10, 20 and 30 mAs, respectively, in the RH region; 5.4, 5.5 and 5.4 for 10, 20 and 30 mAs, respectively, in the RF region; 13.8, 14.9 and 14.5 for 10, 20 and 30 mAs, respectively, in the LV1 region. The three tube current values yielded similar results for SUV calculation.

Cladding tube manufacturing technology

International Nuclear Information System (INIS)

Hahn, R.; Jeong, Y. H.; Baek, B. J.; Kim, K. H.; Kim, S. J.; Choi, B. K.; Kim, J. M.

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 A lloy 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

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.

Heating tubes of cross-linked polyethylene

International Nuclear Information System (INIS)

Knoeppler, H.; Hoffmann, M.

1981-01-01

Oxygen permeability of plastic tubes for floor heating systems was measured as a function of the reduced oxygen content of water in plastic tubes at a flow rate of 0.5 m/s and a temperature of 30 0 C and as a function of oxygen uptake of low-oxygen water in floor heating tubes. Pipes of VEP, periodically cross-linked polyethylene (Engels process), polypropylene copolymeride, and polybutene were compared. The permeability of periodically cross-linked polyethylene is twice as high as that of VEP. Measurements, results, and consequences for floor heating systems are discussed. (KH) [de

A novel readout concept for multianode photomultiplier tubes with pad matrix anode layout

Energy Technology Data Exchange (ETDEWEB)

Popov, Vladimir [Thomas Jefferson National Accelerator Facility, Newport News, VA 23606 (United States)]. E-mail: Popov@jlab.org; Majewski, Stan [Thomas Jefferson National Accelerator Facility, Newport News, VA 23606 (United States); Welch, Benjamin L. [Thomas Jefferson National Accelerator Facility, Newport News, VA 23606 (United States)

2006-11-01

We have developed a new analog readout concept for multianode photomultiplier tubes with a pad matrix anode layout. This new readout technique is the result of a modification of a technique previously developed at the Detector Group of Jefferson Lab (V. Popov, US patent No: 6,747,263 B1) [V. Popov, S. Majewski, A.G. Weisenberger, Readout Electronics for Multianode Photomultiplier Tubes with Pad Matrix Anode Layout, Thomas Jefferson National Accelerator Facility, IEEE 2003 Medical Imaging Conference Record, November 2003]. The new analog readout circuit provides the same analog conversion of matrix 2-D output into X and Y projective output with a significant reduction of analog outputs. The old readout network consists of resistors' matrix and current collecting amplifiers, and it provides decoupling of each anode output into two directions (one to X and one to Y coordinates), but a decoupling function that is carried out independent of photomultiplier tube gains nonuniformity. A newly developed readout network (US patent pending) also consists of resistors' matrix and current collecting amplifiers, but the new matrix includes an additional dumping resistor that provides an excess current from anode pad grounding. As a result, we subtract an extra current of high-gain pads in order to move the pads gain to an absolute minimum value for a given photomultiplier tube. This gain equalization procedure reduces image distortion related to gain nonuniformity. The new readout technique was used in several new radiation imaging detectors designed in the Detector Group of Jefferson Lab. It shows a visible readout uniformity and linearity improvement. The test results of an initial evaluation of this readout that is applied for data readout of four H8500 Hamamtsu PSPMT are presented.

Device for the selective positioning of a component on a tube plate

International Nuclear Information System (INIS)

1974-01-01

The invention relates to a device for the selective positioning of a component on a tube plate. It particularly applies to the positioning of a guide tube head successively opposite all the tubes of the tube bundle of a nuclear reactor steam generator. The large number of tubes in the tube bundle of the steam generator in a pressure water nuclear power station must be checked periodically for any likely corrosion. This check is effected with a Foucault current probe which is inserted in each tube in turn and is connected to a probe signal processing unit. The probe is placed in a flexible guide tube brought in turn in front of each tube of the bundle to be checked. The invention concerns a device to move the opening of a tube guide for a Foucault current detector over the entire surface of the tube plate, thereby providing access to all the tubes whilst limiting the interventions to a single positioning and a single withdrawal of the apparatus for testing all the bundle. Between the two interventions at the beginning and end of the operation, all displacements are remote controlled from outside the dangerous radioacive area [fr

Combining automatic tube current modulation with adaptive statistical iterative reconstruction for low-dose chest CT screening.

Directory of Open Access Journals (Sweden)

Jiang-Hong Chen

Full Text Available To reduce radiation dose while maintaining image quality in low-dose chest computed tomography (CT by combining adaptive statistical iterative reconstruction (ASIR and automatic tube current modulation (ATCM.Patients undergoing cancer screening (n = 200 were subjected to 64-slice multidetector chest CT scanning with ASIR and ATCM. Patients were divided into groups 1, 2, 3, and 4 (n = 50 each, with a noise index (NI of 15, 20, 30, and 40, respectively. Each image set was reconstructed with 4 ASIR levels (0% ASIR, 30% ASIR, 50% ASIR, and 80% ASIR in each group. Two radiologists assessed subjective image noise, image artifacts, and visibility of the anatomical structures. Objective image noise and signal-to-noise ratio (SNR were measured, and effective dose (ED was recorded.Increased NI was associated with increased subjective and objective image noise results (P<0.001, and SNR decreased with increasing NI (P<0.001. These values improved with increased ASIR levels (P<0.001. Images from all 4 groups were clinically diagnosable. Images with NI = 30 and 50% ASIR had average subjective image noise scores and nearly average anatomical structure visibility scores, with a mean objective image noise of 23.42 HU. The EDs for groups 1, 2, 3 and 4 were 2.79 ± 1.17, 1.69 ± 0.59, 0.74 ± 0.29, and 0.37 ± 0.22 mSv, respectively. Compared to group 1 (NI = 15, the ED reductions were 39.43%, 73.48%, and 86.74% for groups 2, 3, and 4, respectively.Using NI = 30 with 50% ASIR in the chest CT protocol, we obtained average or above-average image quality but a reduced ED.

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Pressure loss characteristics of LSTF steam generator heat-transfer tubes. Pressure loss increase due to tube internal instruments

International Nuclear Information System (INIS)

Suzuki, Mitsuhiro

1994-11-01

The steam generator of the Large-Scale Test Facility (LSTF) includes 141 heat-transfer U-tubes with different lengths. Six U-tubes among them are furnished with 15 or 17 probe-type instruments (conduction probe with a thermocouple; CPT) protuberant into the primary side of the U-tubes. Other 135 U-tubes are not instrumented. This results in different hydraulic conditions between the instrumented and non-instrumented U-tubes with the same length. A series of pressure loss characteristics tests was conducted at a test apparatus simulating both types of U-tube. The following pressure loss coefficient (K CPT ) was reduced as a function of Reynolds number (Re) from these tests under single-phase water flow conditions. K CPT =0.16 5600≤Re≤52820, K CPT =60.66xRe -0.688 2420≤Re≤5600, K CPT =2.664x10 6 Re -2.06 1371≤Re≤2420. The maximum uncertainty is 22%. By using these results, the total pressure loss coefficients of full length U-tubes were estimated. It is clarified that the total pressure loss of the shortest instrumented U-tube is equivalent to that of the middle-length non-instrumented U-tube and also that a middle-length instrumented U-tube is equivalent to the longest non-instrumented U-tube. Concludingly. it is important to take account of the CPT pressure loss mentioned above in estimation of fluid behavior at the non-instrumented U-tubes either by using the LSTF experiment data from the CPT-installed U-tubes or by using any analytical codes. (author)

Eddy current testing

Energy Technology Data Exchange (ETDEWEB)

Song, Sung Jin; Lee, Hyang Beom; Kim, Young Hwan [Soongsil Univ., Seoul (Korea, Republic of); Shin, Young Kil [Kunsan Univ., Gunsan (Korea, Republic of)

2004-02-15

Eddy current testing has been widely used for non destructive testing of steam generator tubes. In order to retain reliability in ECT, the following subjects were carried out in this study: numerical modeling and analysis of defects by using BC and RPC probes in SG tube, preparation of absolute coil impedance plane diagram by FEM. Signal interpretation of the eddy current signals obtained from nuclear power plants.

Eddy current testing

International Nuclear Information System (INIS)

Song, Sung Jin; Lee, Hyang Beom; Kim, Young Hwan; Shin, Young Kil

2004-02-01

Eddy current testing has been widely used for non destructive testing of steam generator tubes. In order to retain reliability in ECT, the following subjects were carried out in this study: numerical modeling and analysis of defects by using BC and RPC probes in SG tube, preparation of absolute coil impedance plane diagram by FEM. Signal interpretation of the eddy current signals obtained from nuclear power plants

Revisiting resolution in hydrodynamic countercurrent chromatography: tubing bore effect.

Science.gov (United States)

Berthod, A; Faure, K

2015-04-17

A major challenge in countercurrent chromatography (CCC), the technique that works with a support-free biphasic liquid system, is to retain the liquid stationary phase inside the CCC column (Sf parameter). Two solutions are commercially available: the hydrostatic CCC columns, also called centrifugal partition chromatographs (CPC), with disks of interconnected channels and rotary seals, and the hydrodynamic CCC columns with bobbins of coiled open tube and no rotary seals. It was demonstrated that the amount of liquid stationary phase retained by a coiled tube was higher with larger bore tubing than with small bore tubes. At constant column volume, small bore tubing will be longer producing more efficiency than larger bore tube that will better retain the liquid stationary phase. Since the resolution equation in CCC is depending on both column efficiency and stationary phase retention ratio, the influence of the tubing bore should be studied. This theoretical work showed that there is an optimum tubing bore size depending on solute partition coefficient and mobile phase flow rate. The interesting result of the theoretical study is that larger tubing bores allow for dramatically reduced experiment durations for all solutes: in reversed phase CCC (polar mobile phase), hydrophobic solutes are usually highly retained. These apolar solutes can be separated by the same coil at high flow rates and reduced Sf with similar retention times as polar solutes separated at smaller flow rates and much higher Sf. Copyright © 2015 Elsevier B.V. All rights reserved.

Test and evaluation of the BBC CQK 200-4 modulator tube for the MFTF sustaining neutral beam power supply system

International Nuclear Information System (INIS)

Eckard, R.D.; Van Ness, H.W.; Hesselgrave, D.

1979-01-01

The BBC CQK 200-4 Tube was tested by Aydin at LLL, to confirm that it would switch 90 kV after conducting 88 amperes for 30 seconds. The CQK 200-4 is a recent modification of the CQK 200-3, an Rf transmitter tube designed for continuous loading, to increase the anode hold-off voltage to 150 kV. During the design life of the tube it will be subjected to 10 5 to 10 6 cyclic thermal loads. Two concerns are that (1) during the 30 second high current load, the screen grid may have excessive dissipation causing a loss of control of the tube, and (2) the cyclic temperature-induced stresses in the anode may cause fatigue failures that will reduce the tube's useful life. The first concern was addressed by performing full scale tests at the LLL test facility

Eddy Currents Inspection of CANDU Steam Generator Tubes using Zetec's ZR-1 Robot. Experience in Romania

Energy Technology Data Exchange (ETDEWEB)

Scott Hower [Zetec Inc. (Romania); Luiza Vladu; Adrian Nichisov; Mihai Cretu [COMPCONTROL ING. (Romania)

2006-07-01

Full text of publication follows: The commercial operation of Unit 1 of Cernavoda NPP started on 2 December, 1996. The unit's reactor type is PHWR-CANDU 6 (electrical capacity 706 MWe), using natural uranium. The nuclear fuel is manufactured in Romania. The Cernavoda nuclear power plant has four CANDU - design steam generators that have been in service since 1996. The paper introduces the new ZR-1 Robot System for Inspection and Maintenance/Repair from Zetec that combines the newest state-of-the-art robotics technology with Zetec experience - based innovation to address the needs for inspection and repair of steam generators. The multipurpose ZR-1 can be easily installed to perform the necessary eddy current inspection and remain installed ready for follow-up maintenance and repair. It has superior technical performances and a modular three axis motion of arm that enables 100% coverage of tube sheet. Automated, repeatable, and precise positioning of tool heads ensures accurate delivery and reducing costly rework and reduces inspection time by 30%. The modular, light weight, and portable design permits easy assembly and disassembly through small openings and it reduces setup/tear down time by 30%. The first deployment of the new ZR-1 Robot was made in September 2004 at the Cernavoda NPP inspection outage. The unit's reactor type is PHWR-CANDU 6 (electrical capacity 706 MWe), using natural uranium; the nuclear fuel is manufactured in Romania. The Cernavoda nuclear power plant Unit 1 has four CANDU - design steam generators that have been in service since 1996. The paper presents also the Zetec's field experience and customer experience with this system. It describes the equipment setup in Cernavoda's steam generators mock-up, functional tests and calibration. Finally, provides details on the execution of the inspection, options for standardizing the inspection techniques and conclusions. (authors)

Status of pulse tube development at CEA/SBT

International Nuclear Information System (INIS)

Ravex, A.; Rolland, P.

1994-01-01

Interest in the pulse tube comes from its potential for high reliability and low level of induced vibration. A numerical model has been developed to provide a tool for practical design. It has been successfully validated against the experimental results obtained with a single stage double inlet pulse tube which has achieved a temperature of 28 K at a frequency of a few Hz. Further developments have demonstrated the capability of operating a pulse tube at higher frequencies in association with a Stirling pressure oscillator. Current projects include coaxial geometry for miniature pulse tubes with linear resonant pressure oscillators. A 4 K multistaged pulse tube is also in development. (authors). 5 figs., 12 refs

HV Switch Tube Development Program status report: April 28, 1978

International Nuclear Information System (INIS)

Winje, R.A.

1978-01-01

The HV Switch Tube Development Program encompassed development contracts to both Eimac (Division of Varian) and RCA. Both companies were required to develop a design for the tube and to build and test two tubes. The development program began in April, 1976. Currently, both companies have built tubes; Eimac has built one and RCA has built two. As initially built, both tubes exhibited unstable operation; however, RCA has implemented design changes which stabilized the tube operation. Eimac has a design modification which they believe will produce stable operation when the change is implemented. Both tubes have been tested to a limited degree and no other abnormal characteristics have been observed

Chest tube drainage of pleural effusions--an audit of current practice and complications at Hutt Hospital.

Science.gov (United States)

Epstein, Erica; Jayathissa, Sisira; Dee, Stephen

2012-05-11

The aims of the study were to review small-bore chest tube insertion practices for drainage of pleural fluid at Hutt Valley District Health Board (HVDHB), to assess complications, and compare the findings with international data. Retrospective analysis of clinical records was completed on all chest tube insertions for drainage of pleural fluid at HVDHB from December 2008 to November 2009. Descriptive statistics were used to present demographics and tube-associated complications. Comparison was made to available similar international data. Small-bore tubes comprised 59/65 (91%) chest tube insertions and 23/25 (92%) complications. Available comparative data was limited. Ultrasound was used in 36% of insertions. Nearly half of chest drains placed for empyema required subsequent cardiothoracic surgical intervention. Chest drain complication rates at HVDHB were comparable to those seen internationally. Referral rates to cardiothoracic surgery for empyema were within described ranges. The importance of procedural training for junior medical staff, optimising safety of drain insertions with ultrasound guidance, and clear clinical governance for chest tube insertions are important in minimising harm from this procedure. Specialist societies need to take a leadership in providing guidance on chest drain insertions to secondary and tertiary hospitals in Australia and New Zealand.

Application of non-destructive liner thickness measurement technique for manufacturing and inspection process of zirconium lined cladding tube

International Nuclear Information System (INIS)

Nakazawa, Norio; Fukuda, Akihiro; Fujii, Noritsugu; Inoue, Koichi

1986-01-01

Recently, in order to meet the difference of electric power demand owing to electric power situation, large scale load following operation has become necessary. Therefore, the development of the cladding tubes which withstand power variation has been carried out, as the result, zirconium-lined zircaloy 2 cladding tubes have been developed. In order to reduce the sensitivity to stress corrosion cracking, these zirconium-lined cladding tubes require uniform liner thickness over the whole surface and whole length. Kobe Steel Ltd. developed the nondestructive liner thickness measuring technique based on ultrasonic flaw detection technique and eddy current flaw detection technique. These equipments were applied to the manufacturing and inspection processes of the zirconium-lined cladding tubes, and have demonstrated superiority in the control and assurance of the liner thickness of products. Zirconium-lined cladding tubes, the development of the measuring technique for guaranteeing the uniform liner thickness and the liner thickness control in the manufacturing and inspection processes are described. (Kako, I.)

Method of evaluation of stress corrosion cracking susceptibility of clad fuel tubes

International Nuclear Information System (INIS)

Takase, Iwao; Yoshida, Toshimi; Ikeda, Shinzo; Masaoka, Isao; Nakajima, Junjiro.

1986-01-01

Purpose: To determine, by an evaluation in out-pile test, the stress corrosion cracking susceptibility of clad fuel tubes in the reactor environment. Method: A plurality of electrodes are mounted in the circumferential direction on the entire surface of cladding tubes. Of the electrodes, electrodes at two adjacent places are used as measuring terminals and electrodes at another two places adjacent thereto are used as constant-current terminals. With a specific current flowing in the constant-current terminals, measurements are made of a potential difference between the terminals to be measured, and from a variation in the potential difference the depth of cracking of the cladding tube surface is presumed to determine the stress corrosion cracking susceptibility of the cladding tube. To check the entire surface of the cladding tube, the cladding tube is moved by each block in the circumferential direction by a contact changeover system, repeating the measurements of the potential difference. Contact type electrodes are secured with an insulator and held in uniform contact with the cladding tube by a spring. It is detachable by use of a locking system and movable as desired. Thus the stress corrosion cracking susceptibility can be determined without mounting the cladding tube through and also a fuel failure can be prevented. (Horiuchi, T.)

Means and method for controlling the neutron output of a neutron generator tube

International Nuclear Information System (INIS)

1980-01-01

A specification is given for an energizing and regulating circuit for a gas filled neutron generator tube consisting of a target, an ion source and a replenisher, the circuit consisting of a power supply to provide a negative high voltage to the target and a target current corresponding to the neutron output of the tube, a constant current source, and control means connected to the power supply and to the constant current source, the control means being responsive to the target current to provide a portion of the constant current to the replenisher substantially to regulate the neutron output of the tube. (author)

Experimental evaluation of emergency operating procedures on multiple steam generator tube rupture in INER integral system test facility

International Nuclear Information System (INIS)

Liu, T.J.; Lin, Y.M.; Lee, C.H.; Chang, C.Y.; Hong, W.T.

1997-01-01

The multiple steam generator tube rupture (SGTR) scenario in Westinghouse type pressurized water reactor (PWR) has been investigated at the Institute of Nuclear Energy Research (INER) Integral System Test (IIST) facility. This reduced-height and reduced-pressure test facility was designed to simulate the main features of Maanshan nuclear power plant. The SGTR test scenario assumes the double-ended break of one-, two- and six- tubes without other failures. The major operator actions follow the related symptom-oriented Emergency Operating Procedure (EOP) on the reference plant. This study focuses on the investigation of thermal-hydraulics phenomena and the adequacy of associated EOP to limit primary-to-secondary leakage. Through this study, it is found that the adequacy of current EOP in minimizing the radioactivity release demands early substantial operator involvement, especially in the multi-tubes break events. Also, the detailed mechanism of the main thermal-hydraulic phenomena during the SGTR transient are explored. (author)

Application of automatic tube current modulation with 64-detector CT in infant brain

International Nuclear Information System (INIS)

Li Jianming; Xu Wenbiao; Luo Yuanli; Liu Hongsheng; Zhou Ning

2010-01-01

Objective: To evaluate the effect of automatic tube modulation on imaging quality and lesion revealed in infant brain. Methods: The infant patients of 200 cases were divided into four groups according to the values of SD (2.5, 2.75, 3.0, 4.0), 50 cases in each group. They were performed with the automatic tube current modulation scanning in brain. The imaging quality and radiation dose were analyzed. Results: When the values of SD were 2.5, 2.75, 3.0 and 4.0, the high values of CTDI vol were 60.0, 49.8, 42.9 and 25.8 mGy, respectively. The effective doses were (3.27±1.01), (2.78±0.85), (2.40±0.74) and (1.49±0.45) mSv·mGy -1 ·cm -1 , respectively. There was significant difference among those groups (F=48.99, P<0.05). The excellent imaging qualities were 100%, 96%, 70% and 20%, 12 cases were neonate in SD 2.5 group. In SD 2.75 group, the imaging quality of neonate (2 cases) were all fine. In SD 3.0 group, the imaging quality was not ideal for the ages less than 1 year. In SD 4.0 group, when the infants aged over 2 years and 6 months, or with the larger head circumference, their imaging quality were all excellent. Conclusions: The individual application of ATCM could obtain the best balance among imaging quality, radiation dose and diagnostic quality. The SD 2.5, 2.75, 3.0 and 4.0 might be suitable to infants of newborn, 1 month to 1 year old, 1 to 3 years, the larger head circumference and part of the reviewed cases. (authors)

Guided waves in magnetospheric tubes of enhanced density

International Nuclear Information System (INIS)

Maltsev, Yu.P.; Lyatsky, W.B.

1981-01-01

Properties of a guided MHD-wave propagating in a magnetic field tube with the plasma density differing from the ambient density are studied. Like the Alven wave this wave propagates along the magnetic field and is connected with the field-aligned currents flowing at the periphery of the oscillating tube. The guided wave is accompanied by the magnetic field compression, nevertheless the wave moves without attenuation. The guided wave velocity is between the Alven velocities inside and outside the oscillating tube. In a tube of elliptical cross-section the propagation velocity depends on the polarization of the wave. (author)

Statistics applied to the testing of cladding tubes

International Nuclear Information System (INIS)

Perdijon, J.

1987-01-01

Cladding tubes, either steel or zircaloy, are generally given a 100 % inspection through ultrasonic non-destructive testing. This inspection may be completed beneficially with an eddy current test, as this is not sensitive to the same defects as those typically traced by ultrasonic testing. Unfortunately, the two methods (as with other non-destructive tests) exhibit poor precision; this means that a flaw, whose size is close to that denoted as rejection limit, may be accepted or rejected. Currently, rejection, i.e. the measurement above which a tube is rejected, is generally determined through measuring a calibration tube at regular time intervals, and the signal of a given tube is compared to that of the most recently completed calibration. This measurement is thus subject to variations which can be attributed to an actual shift of adjustments as well as to poor precision. For this reason, monitoring instrument adjustments using the so-called control chart method are proposed

Influence of tube volume on measurement uncertainty of GM counters

Directory of Open Access Journals (Sweden)

Stanković Koviljka Đ.

2010-01-01

Full Text Available GM counters are often used in radiation detection since they generate a strong signal which can be easily detected. The working principal of a GM counter is based on the interaction of ionizing radiation with the atoms and molecules of the gas present in the counter's tube. Free electrons created as a result of this interaction become initial electrons, i. e. start an avalanche process which is detected as a pulse of current. This current pulse is independent of the energy imparted on the gas, that being the main difference between a GM counter and the majority of other radiation detectors. In literature, the dependence on the incidence of radiation energy, tube's orientation and characteristics of the reading system are quoted as the main sources of measurement uncertainty of GM counters. The aim of this paper is to determine the dependence of measurement uncertainty of a GM counter on the volume of its counter's tube. The dependence of the pulse current on the size of the counter's tube has, therefore, been considered here, both in radial and parallel geometry. The initiation and expansion of the current pulse have been examined by means of elementary processes of electrical discharge such as the Markov processes, while the changes in the counter's tube volume were put to test by the space - time enlargement law. The random variable known as the 'current pulse in the counter's tube' (i. e. electrical breakdown of the electrode configuration has also been taken into account and an appropriate theoretical distribution statistically determined. Thus obtained theoretical results were then compared to corresponding experimental results established in controlled laboratory conditions.

Colour coding for blood collection tube closures - a call for harmonisation.

Science.gov (United States)

Simundic, Ana-Maria; Cornes, Michael P; Grankvist, Kjell; Lippi, Giuseppe; Nybo, Mads; Ceriotti, Ferruccio; Theodorsson, Elvar; Panteghini, Mauro

2015-02-01

At least one in 10 patients experience adverse events while receiving hospital care. Many of the errors are related to laboratory diagnostics. Efforts to reduce laboratory errors over recent decades have primarily focused on the measurement process while pre- and post-analytical errors including errors in sampling, reporting and decision-making have received much less attention. Proper sampling and additives to the samples are essential. Tubes and additives are identified not only in writing on the tubes but also by the colour of the tube closures. Unfortunately these colours have not been standardised, running the risk of error when tubes from one manufacturer are replaced by the tubes from another manufacturer that use different colour coding. EFLM therefore supports the worldwide harmonisation of the colour coding for blood collection tube closures and labels in order to reduce the risk of pre-analytical errors and improve the patient safety.

Evaluation of reliability of EC inspection of VVER SG tubes

International Nuclear Information System (INIS)

Stanic, D.

2001-01-01

Evaluation of eddy current data collected during inspection of VVER steam generators is very complex task because of numerous parameters which have affect on eddy current signals. That was the reason that recently ago INETEC has started related scientific project in order to evaluate the reliability of eddy current (EC) inspection of VVER steam generator (SG) tubing. In the scope of project the following objectives will be investigated: 1. Determination of POD (Probability of detection) of various types degradation cracks, where their basic parameters are variables (basic parameters are depth, length, width, orientation, number) on three different sets of tubes (clean ideal tubes, tubes with pilgering, tubes electroplated with copper) 2. Sizing quality (accuracy, repeatability) (same data sets as defined in 1.) 3. Effect of fill factor on POD and sizing quality. 4. Effect of tube bends on POD and sizing quality. 5. Effect of other tube geometry variations on POD and sizing quality (tube ovality, transition zone region, expanded (rolled) part of tube, dents, dings). Investigation will start with bobbin probe technique which is the most used technique for general purpose VVER tube examination. Since INETEC is the only world company which successfully developed and applied rotating probe technique for VVER SG tubes, scope of the project will be extended on rotating probe technique utilizing 'pancake' and 'point' coil. Method reliability will be investigated first on the huge set of EDM notches representing various defect morphologies and simulating different factors, and the second part will be investigated on sets of degradation defects obtained by artificial corrosion. In the scope of the project the measures for enhancing the method reliability have to be determined. This considers the proper definition of parameters of examination system, as well as establishment of the suitable analysis procedures. This article presents the temporary results of the first part of

Feedwater heater tube-to-tubesheet connections

International Nuclear Information System (INIS)

Yokell, S.

1993-01-01

This paper discusses some practical aspects of expanded, welded, and welded-and-expanded feedwater heater tube-to-tubesheet joints. It outlines elastic-plastic tube expanding theory. It examines uniform-pressure-expanded tube joint strength and correlating roller-expanded joint strength with wall reduction and rolling torque. For materials subject to stress-corrosion cracking (SCC), it recommends heat treating tube ends before expanding. For materials subject to fatigue and tube-end cracking, it advocates two-stage expanding: (1) expanding enough to create firm tube-hole contact over the full tubesheet thickness; and (2) re-expanding at full pressure or torque. The paper emphasizes the desirability of segregating heats of tubing, mapping the tube-heat locations and making the heat map a permanent part of the heater maintenance file. It recommends when to provide TEMA/HEI Power Plant Standard annular grooves for roller-expanding and provides an equation for determining optimum groove width for uniform-pressure expanding. The paper also reviews welding requirements for welds of tubes to tubesheets. The review covers front-face welding before and after expanding and the reasons for welding first. It outlines current thinking about definitions of strength- and seal-welds of front-face welded joint in terms of their functions and load-carrying abilities. It presents a proposal for determining the required size of strength welds for use in Section VIII of the ASME Boiler and Pressure Vessel Code (the Code). It shows why welded-and-expanded feedwater heater tube-to-tubesheet joints should be full-strength and full-depth expanded. It makes recommendations for pressure- and leak-testing. This work also proposes the industry consider butt welding the tubes to the steam-side face of the tubesheet as a regular method of tube joining. The results of a survey of manufacturers practices are appended. 30 refs., 14 figs

Remote field eddy current testing

International Nuclear Information System (INIS)

Cheong, Y. M.; Jung, H. K.; Huh, H.; Lee, Y. S.; Shim, C. M.

2001-03-01

The state-of-art technology of the remote field eddy current, which is actively developed as an electromagnetic non-destructive testing tool for ferromagnetic tubes, is described. The historical background and recent R and D activities of remote-field eddy current technology are explained including the theoretical development of remote field eddy current, such as analytical and numerical approach, and the results of finite element analysis. The influencing factors for actual applications, such as the effect of frequency, magnetic permeability, receiving sensitivity, and difficulties of detection and classification of defects are also described. Finally, two examples of actual application, 1) the gap measurement between pressure tubes and calandria tube in CANDU reactor and, 2) the detection of defects in the ferromagnetic heat exchanger tubes, are described. The future research efforts are also included

A prospective evaluation of contrast and radiation dose and image quality in cardiac CT in children with complex congenital heart disease using low-concentration iodinated contrast agent and low tube voltage and current.

Science.gov (United States)

Hou, Qiao-Ru; Gao, Wei; Sun, Ai-Min; Wang, Qian; Qiu, Hai-Sheng; Wang, Fang; Hu, Li-Wei; Li, Jian-Ying; Zhong, Yu-Min

2017-02-01

To the assess image quality, contrast dose and radiation dose in cardiac CT in children with congenital heart disease (CHD) using low-concentration iodinated contrast agent and low tube voltage and current in comparison with standard dose protocol. 110 patients with CHD were randomized to 1 of the 2 scan protocols: Group A (n = 45) with 120 mA tube current and contrast agent of 270 mgI/ml in concentration (Visipaque ™ ; GE Healthcare Ireland, Co., Cork, UK); and Group B (n = 65) with the conventional 160 mA and 370 mgI/ml concentration contrast (Iopamiro ® ; Shanghai Bracco Sine Pharmaceutical Corp Ltd, Shanghai, China). Both groups used 80 kVp tube voltage and were reconstructed with 70% adaptive statistical iterative reconstruction algorithm. The CT value and noise in aortic arch were measured and the signal-to-noise ratio (SNR) and contrast-to-noise ratio (CNR) were calculated. A five-point scale was used to subjectively evaluate image quality. Contrast and radiation dose were recorded. There was no difference in age and weight between the two groups (all p > 0.05). The iodine load and radiation dose in Group A were statistically lower (3976 ± 747 mgI vs 5763 ± 1018 mgI in iodine load and 0.60 ± 0.08 mSv vs 0.77 ± 0.10 mSv in effective dose; p  0.05), and with good agreement between the two observers. Comparing the surgery results, the diagnostic accuracy for extracardiac and intracardiac defects for Group A was 96% and 92%, respectively, while the corresponding numbers for Group B were 95% and 93%. Compared with the standard dose protocol, the use of low tube voltage (80 kVp), low tube current (120 mA) and low-concentration iodinated contrast agent (270 mgI/ml) enables a reduction of 30% in iodine load and 22% in radiation dose while maintaining compatible image quality and diagnostic accuracy. Advances in knowledge: The new cardiac CT scanning protocol can largely reduce the adverse effects of

Marketing Strategy of YouTube in the Czech Republic

OpenAIRE

Hurychová, Andrea

2012-01-01

The goals of the thesis are to present YouTube in the Czech Republic, to discuss its entire business model, analyze the main local competitors and mostly to suggest marketing strategy that will strengthen the position of YouTube as an online medium. The current trends in the internet society are introduced as well as the role of social media in order to understand how these factors are related to the position of YouTube in marketing. From general YouTube introduction the situation of this pla...

Automatic integrated testing bench for tubes in translation

International Nuclear Information System (INIS)

Dufayet, J.P.; Perdijon, J.

1976-01-01

All the nondestructive tests required for receiving the cladding tubes intended for fast nuclear reactor are integrated on this bench: quality control by eddy currents and ultra-sounds, thickness and (inner and outer) diameter measurement. The linear displacement of the tube allows very high rates to be attained [fr

Stability of spiral welded tubes in Quay Walls

NARCIS (Netherlands)

Gresnigt, A.M.; van Es, S.H.J.

2013-01-01

A European research project (RFCS) has started to provide economic and safe guidance for the design of spirally welded tubes in combined walls. The main motivation for this project called COMBITUBE is that the current Eurocode 3 regulations for tubes in quay walls lead to uneconomic designs, because

Force-free thin flux tubes: Basic equations and stability

International Nuclear Information System (INIS)

Zhugzhda, Y.D.

1996-01-01

The thin flux tube approximation is considered for a straight, symmetrical, force-free, rigidly rotating flux tube. The derived set of equations describes tube, body sausage, and Alfveacute charn wave modes and is valid for any values of Β. The linear waves and instabilities of force-free flux tubes are considered. The comparison of approximate and exact solutions for an untwisted, nonrotating flux tube is performed. It is shown that the approximate and exact dispersion equations coincides, except the 20% discrepancy of sausage frequencies. An effective cross section is proposed to introduce the removal of this discrepancy. It makes the derived approximation correct for the force-free thin flux tube dynamics, except the detailed structure of radial eigenfunction. The dispersion of Alfveacute charn torsional waves in a force-free tubes appears. The valve effect of one directional propagation of waves in rotating twisted tube is revealed. The current and rotational sausage instabilities of a force-free, thin flux tube are considered. copyright 1996 American Institute of Physics

New Czechoslovak detector of leaking condenser tubes usable in both shutdown and reduced output operation of power unit

International Nuclear Information System (INIS)

Matal, O.; Klinga, J.; Varvarovsky, F.; Zachar, J.; Fratric, D.

1986-01-01

The main reason for penetration of undesirable admixtures from cooling water in the condensate is the inleakage of steam turbine condensers. Briefly assessed are the means and methods of detecting and locating condenser leaks used in the world and in power facilities in Czechoslovakia. Equipment was developed based on measuring the difference between the pressure in a temporarily closed condenser tube and ambient pressure, for leak testing of condenser tubes during operation and during shutdown of WWER-440 units. Two types of the equipment were tested in practice. Type VUEZ-PHN 85P meets the requirements of objective leak tests and those of leak location in condenser tubes and of leak detection in tube expansion in the tube plates of WWER-440 unit condensers, this as concerns sensitivity, the objectivity of results, the cost of tests, and minimal losses of power during the test. Type VUEZ-PHN 85P can be used for leak location in all tube type heat exchangers with access to tube outlets in which under- or overpressure can be achieved in the space between the tubes relative to ambient pressure during the test. (Z.M.) 5 figs., 4 tabs., 11 refs

Template synthesis of test tube nanoparticles using non-destructive replication.

Science.gov (United States)

Wagner, Jonathan; Yao, Jingyuan; Rodgers, David; Hinds, Bruce

2013-03-01

Nano test tubes are a promising delivery vehicle for a range of therapeutics, including small molecule drugs and biologics. However, current template synthesis methods of producing nano test tubes are prohibitively expensive and time consuming. Here, non-destructive template replication was used to increase nano test tube yield from porous alumina by more than a hundredfold. We demonstrate how to produce nano test tubes of several sizes and compositions, including hybrid tubes with different inner and outer surfaces for targeted surface chemistry. Nano test tubes were readily suspended and stored in aqueous solutions without the need for chemical treatment. These nano test tubes should find application as delivery vehicles for therapeutics, particularly for processive 'bionanoreactors' loaded with enzymes.

Medical Informatics Idle YouTube Potential.

Science.gov (United States)

Hucíková, Anežka; Babic, Ankica

2017-01-01

YouTube as an online video-sharing service in the context of Web 2.0 goes beyond the bounds of pure fun, for which the platform was primarily established. Nowadays, commonly to other social media, it serves also educational, informational and last but not least, marketing purposes. The importance of video sharing is supported by several predictions about video reaching over 90% of global internet traffic by 2020. Using qualitative content analysis over selected YouTube videos, paper examines the current situation of the platform's marketing potential usage by medical informatics organizations, researches and other healthcare professionals. Results of the analysis demonstrate several ways in which YouTube is already used to inform, educate or promote above-mentioned medical institutions. However, their engagement in self-promo or spreading awareness of their research projects via YouTube is considered to be low.

Energy losses in the D0 β solenoid cryostat caused by current changes

International Nuclear Information System (INIS)

Visser, A.T.

1993-11-01

The proposed D0 β solenoid is a superconducting solenoid mounted inside an aluminum tube which supports the solenoid winding over it's full length. This aluminum support tube, also called bobbin, is therefore very tightly coupled to magnetic flux changes caused by solenoid current variations. These current changes in the solenoid, will cause answer currents to flow in the resistive bobbin wall and therefore cause heat losses. The insertion of an external dump resistor in the solenoid current loop reduces energy dissipation inside the cryostat during a quench and will shorten the discharge time constant. This note presents a simple electrical model for the coupled bobbin and solenoid and makes it easier to understand the circuit behavior and losses. Estimates for the maximum allowable rate of solenoid current changes, based on the maximum permissible rate of losses can be made using this model

Flooding experiments with steam and water in a large diameter vertical tube

International Nuclear Information System (INIS)

Williams, S.N.; Solom, M.; Draznin, O.; Choutapalli, I.; Vierow, K.

2009-01-01

An experimental study on flooding in a large diameter tube is being conducted. In a countercurrent, two-phase flow system, flooding can be defined as the onset of flow reversal of the liquid component which results in cocurrent flow. Flooding can be perceived as a limit to two-phase countercurrent flow, meaning that pairs of liquid and gas flow rates exist that define the envelope for stable countercurrent flow for a given system. Flooding in the AP600 pressurizer surge line can affect the vessel refill rate following a small break LOCA. Analysis of hypothetical severe accidents with current simplified flooding models show that these models represent the largest uncertainty in steam generator tube creep rupture. During a hypothetical station blackout scenario without auxiliary feedwater recovery, should the hot leg become voided, the pressurizer liquid will drain to the hot leg and flooding may occur in the surge line. Experiments have been conducted in a 3-inch (76.2 mm) diameter tube with subcooled water and superheated steam as the working fluids at atmospheric pressure. Water flows down the inside of the tube as an annulus while the steam flows upward in the middle. Water flow rates vary from 3.5 to 12 GPM (0.00022 to 0.00076 m 3 /s) and the water inlet temperature is about 70degC. The steam inlet temperature is about 110degC. It was found that a larger steam flow rate was needed to achieve flooding for a lower water flow rate and for a higher water flow rate. This unique data for flooding in steam-water systems in large diameter tubes will reduce uncertainty in flooding models currently utilized in reactor safety codes. (author)

Researching the Performance of Dual-Chamber Fire-Tube Boiler Furnace

Directory of Open Access Journals (Sweden)

Khaustov Sergei

2015-01-01

Full Text Available Autonomous heating systems equipped with fire-tube or shell boilers show high effectiveness, consistent performance and great technical parameters. But there is a significant limitation of its thermal productivity due to the complexity of durable large diameter fire-tube bottoms implementation. Optimization of combustion aerodynamics can be the way to expand the fire-tube boilers performance limit. In this case lots of problems connected with reducing emissions of toxic substances, providing of burning stability, local heat stresses and aerodynamic resistances should be solved. To resolve the indicated problems, a modified model of dual-chamber fire-tube boiler furnace is proposed. The performance of suggested flame-tube was simulated using the proven computer-aided engineering software ANSYS Multiphysics. Results display proposed flame tube completely filled with moving medium without stagnant zones. Turbulent vortical combustion is observed even with the straight-through fuel supply. Active flue gas recirculation in suggested dual-chamber furnace reduces emissions of pollutants. Diminution of wall heat fluxes allows boiler operation at lower water treatment costs.

Spiral counter-current chromatography of small molecules, peptides and proteins using the spiral tubing support rotor.

Science.gov (United States)

Knight, Martha; Finn, Thomas M; Zehmer, John; Clayton, Adam; Pilon, Aprile

2011-09-09

An important advance in countercurrent chromatography (CCC) carried out in open flow-tubing coils, rotated in planetary centrifuges, is the new design to spread out the tubing in spirals. More spacing between the tubing was found to significantly increase the stationary phase retention, such that now all types of two-phase solvent systems can be used for liquid-liquid partition chromatography in the J-type planetary centrifuges. A spiral tubing support (STS) frame with circular channels was constructed by laser sintering technology into which FEP tubing was placed in 4 spiral loops per layer from the bottom to the top and a cover affixed allowing the tubing to connect to flow-tubing of the planetary centrifuge. The rotor was mounted and run in a P.C. Inc. type instrument. Examples of compounds of molecular weights ranging from <300 to approximately 15,000 were chromatographed in appropriate two-phase solvent systems to assess the capability for separation and purification. A mixture of small molecules including aspirin was completely separated in hexane-ethyl acetate-methanol-water. Synthetic peptides including a very hydrophobic peptide were each purified to a very high purity level in a sec-butanol solvent system. In the STS rotor high stationary phase retention was possible with the aqueous sec-butanol solvent system at a normal flow rate. Finally, the two-phase aqueous polyethylene glycol-potassium phosphate solvent system was applied to separate a protein from a lysate of an Escherichia coli expression system. These experiments demonstrate the versatility of spiral CCC using the STS rotor. Copyright © 2011 Elsevier B.V. All rights reserved.

Conservatism in methodologies for moderator subcooling sufficiency for fuel channel integrity upon pressure tube and calandria tube contact

Energy Technology Data Exchange (ETDEWEB)

Sun, L., E-mail: LSun@nbpower.com [Point Lepreau Generating Station, Lepreau, NB, (Canada)

2015-07-01

During a postulated large LOCA event in CANDU reactors, the pressure tube may balloon to contact with its surrounding calandria tube to transfer heat to the moderator. To confirm the integrity of the fuel channel in this case, many experiments have been performed in the last three decades. Based on the extant database of the pressure tube/calandria tube (PT/CT) contact, an analytical methodology was developed by Canadian Nuclear Industry to determine the sufficiency of moderator subcooling for fuel channel integrity. At the same time a semi-empirical methodology with an idea of Equivalent Moderator Subcooling (EMS) was also developed to judge the sufficiency of the moderator. In this work, some discussions were made over the two methodologies on their conservatism and it is demonstrated that the analytical approach is over conservative comparing with the EMS methodology. By using the EMS methodology, it is demonstrated that applying glass-peened calandria tubes, the requirement to moderator subcooling can be reduced by 10{sup o}C from that for smooth calandria tubes. (author)

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.

Colour coding for blood collection tube closures - a call for harmonisation

DEFF Research Database (Denmark)

Simundic, Ana-Maria; Cornes, Michael P; Grankvist, Kjell

2015-01-01

including errors in sampling, reporting and decision-making have received much less attention. Proper sampling and additives to the samples are essential. Tubes and additives are identified not only in writing on the tubes but also by the colour of the tube closures. Unfortunately these colours have...... not been standardised, running the risk of error when tubes from one manufacturer are replaced by the tubes from another manufacturer that use different colour coding. EFLM therefore supports the worldwide harmonisation of the colour coding for blood collection tube closures and labels in order to reduce...

Comparison of standardized uptake values measured on 18F-NaF PET/CT scans using three different tube current intensities

International Nuclear Information System (INIS)

Valadares, Agnes Araujo; Woellner, Eduardo Bechtloff; Sapienza, Marcelo Tatit; Buchpiguel, Carlos Alberto

2015-01-01

Objective: to analyze standardized uptake values (SUVs) using three different tube current intensities for attenuation correction on 18 FNaF PET/CT scans. Materials and methods: a total of 254 18 F-NaF PET/CT studies were analyzed using 10, 20 and 30 mAs. The SUVs were calculated in volumes of interest (VOIs) drawn on three skeletal regions, namely, right proximal humeral diaphysis (RH), right proximal femoral diaphysis (RF), and first lumbar vertebra (LV1) in a total of 712 VOIs. The analyses covered 675 regions classified as normal (236 RH, 232 RF, and 207 LV1). Results: mean SUV for each skeletal region was 3.8, 5.4 and 14.4 for RH, RF, and LV1, respectively. As the studies were grouped according to mAs value, the mean SUV values were 3.8, 3.9 and 3.7 for 10, 20 and 30 mAs, respectively, in the RH region; 5.4, 5.5 and 5.4 for 10, 20 and 30 mAs, respectively, in the RF region; 13.8, 14.9 and 14.5 for 10, 20 and 30 mAs, respectively, in the LV1 region. Conclusion: the three tube current values yielded similar results for SUV calculation. (author)

Apparatus for securing structural tubes in nuclear reactor fuel assemblies

International Nuclear Information System (INIS)

Kerry, J.S.

1987-01-01

This patent describes a nuclear reactor fuel assembly having a structural tube with a predetermined inside diameter, a generally cylindrical insert of an axial length substantially smaller than the axial length of the structural tube and having a generally cylindrical passageway of a predetermined diameter smaller than the predetermined inside diameter for providing an effectively reduced inside diameter for the structural tube. The insert comprises: means, having an outside diameter approximately equal to the predetermined inside diameter, for coaxially centering the insert within the structural tube; forming lobes, operable when expanded to locally deform against the structural tube thereby locking the insert within the structural tube

Ultrasonic Concentration in a Line-Driven Cylindrical Tube

Energy Technology Data Exchange (ETDEWEB)

Goddard, Gregory Russ [Portland State Univ., Portland, OR (United States)

2004-01-01

The fractionation of particles from their suspending fluid or noninvasive micromanipulation of particles in suspension has many applications ranging from the recovery of valuable reagents from process flows to the fabrication of microelectromechanical devices. Techniques based on size, density, solubility, or electromagnetic properties exist for fulfilling these needs, but many particles have traits that preclude their use such as small size, neutral buoyancy, or uniform electromagnetic characteristics. While separation by those techniques may not be possible, often compressibility differences exist between the particle and fluid that would allow fractionation by acoustic forces. The potential of acoustic separation is known, but due to inherent difficulties in achieving and maintaining accurate alignment of the transduction system, it is rarely utilized. The objective of this project is to investigate the use of structural excitation as a potentially efficient concentration/fractionation method for particles in suspension. It is demonstrated that structural excitation of a cylindrically symmetric cavity, such as a tube, allows non-invasive, fast, and low power concentration of particles suspended in a fluid. The inherent symmetry of the system eliminates the need for careful alignment inherent in current acoustic concentration devices. Structural excitation distributes the acoustic field throughout the volume of the cavity, which also significantly reduces temperature gradients and acoustic streaming in the fluid; cavitation is no longer an issue. The lowest-order coupled modes of a long cylindrical glass tube and fluid-filled cavity, driven by a line contact, are tuned, via material properties and aspect ratio, to achieve a coupled dipolar vibration of the system, shown to generate efficient concentration of particles to the central axis of the tube. A two dimensional elastodynamic model of the system was developed and subsequently utilized to optimize particle

Tubing and cable cutting tool

Science.gov (United States)

Mcsmith, D. D.; Richardson, J. I. (Inventor)

1984-01-01

A hand held hydraulic cutting tool was developed which is particularly useful in deactivating ejection seats in military aircraft rescue operations. The tool consists primarily of a hydraulic system composed of a fluid reservoir, a pumping piston, and an actuator piston. Mechanical cutting jaws are attached to the actuator piston rod. The hydraulic system is controlled by a pump handle. As the pump handle is operated the actuator piston rod is forced outward and thus the cutting jaws are forced together. The frame of the device is a flexible metal tubing which permits easy positioning of the tool cutting jaws in remote and normally inaccessible locations. Bifurcated cutting edges ensure removal of a section of the tubing or cable to thereby reduce the possibility of accidental reactivation of the tubing or cable being severed.

Measurement of unsteady flow forces in inline and staggered tube bundles with fixed and vibrating tubes

International Nuclear Information System (INIS)

Michel, A.; Heinecke, E.; Decken, C.B. von der.

1986-01-01

Unsteady flow forces arising in heat exchangers with cross-flow may lead to serious vibrations of the tubes. These vibrations can destroy the tubes in the end supports or in the baffles, which would require expensive repairs. The flow forces reach unexpectedly by high values if the vibration of the tube intensifies these forces. To clear up this coupling mechanism the flow forces and the vibration amplitude were measured simultaneously in a staggered and in an inline tube bundle. Considering the tube as a one-mass oscillator excited by the flow force, the main parameters can be derived, i.e. dynamic pressure, reduced mass, eigenfrequency and damping. These parameters form a dimensionless model number describing the coherence of the vibration amplitude and the force coefficient. The validity of this number has been confirmed by varying the test conditions. With the aid of this model number, the expected force coefficient can be calculated and then using a finite-element program information can be obtained about mechanical tensions and the lifetime of the heat exchanger tubes. With this model number the results of other authors, who measured the vibration amplitude only, could be confirmed in good agreement. The experiments were carried out in air with Reynolds numbers 10 4 5 . (orig.) [de

On Poor Separation in Magnetically Driven Shock Tube

DEFF Research Database (Denmark)

Chang, C.T.

1973-01-01

Observations made at steady-state running conditions in a magnetically driven shock tube, with parallel-plate electrodes, showed that for a given discharge voltage, sufficient separation between the shock and the current-sheet occurred only at relatively high discharge pressures. As a comparison......, poor separations were also noted in conventional diaphragm-type shock tubes running at low initial pressures. It is demonstrated that the observed poor separation can be explained by a mass leakage, instead of through the wall boundary layer, but through the current-sheet itself....

Opposed slant tube diabatic sorber

Science.gov (United States)

Erickson, Donald C.

2004-01-20

A sorber comprised of at least three concentric coils of tubing contained in a shell with a flow path for liquid sorbent in one direction, a flow path for heat transfer fluid which is in counter-current heat exchange relationship with sorbent flow, a sorbate vapor port in communication with at least one of sorbent inlet or exit ports, wherein each coil is coiled in opposite direction to those coils adjoining it, whereby the opposed slant tube configuration is achieved, with structure for flow modification in the core space inside the innermost coil.

Counteracting the Influence of Peer Smoking on YouTube

OpenAIRE

Romer, Daniel; Jamieson, Patrick E.; Jamieson, Kathleen Hall; Jones, Christopher; Sherr, Susan

2017-01-01

YouTube, a popular online site for user-generated content, is emerging as a powerful source of peer modeling of smoking. Previous research suggests that in counteracting such influence, health messages may inadvertently increase the perceived prevalence of drug use (a descriptive norm) without reducing its acceptability (injunctive norm). This research tested the ability of health messages to reduce the social acceptability of peer smoking on YouTube despite enhancing its perceived prevalence...

Tube welding by the pulsed tig method

International Nuclear Information System (INIS)

Dick, N.T.

1973-01-01

During the construction of the helical wound boiler pods for the AGR stations at Hartlepool and Heysham, automatic TIG-welding techniques were used. In some cases limited access excluded the use of wire feed techniques and autogenous techniques had to be used. To resolve the problem of excessive concavity which occurred when using constant current autogenous techniques on 14.5 mm OD mild steel tubes of 1.8 mm thickness, pulsed-TIG welding was applied. By modifying the trailing edge of the pulse to produce a crater fill with each pulse, susceptibility to porosity and solidification cracking was reduced. The incorporation of digital counter permitted pulse duration, background duration, and electrode indexing distance to be monitored. (U.K.)

21 CFR 868.5800 - Tracheostomy tube and tube cuff.

Science.gov (United States)

2010-04-01

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

Sleeving repair of heat exchanger tubes

International Nuclear Information System (INIS)

Street, Michael D.; Schafer, Bruce W.

2000-01-01

Defective heat exchanger tubes can be repaired using techniques that do not involve the cost and schedule penalties of component replacement. FTI's years of experience repairing steam generator tubes have been successfully applied to heat exchangers. Framatome Technologies heat exchanger sleeves can bridge defective areas of the heat exchanger tubes, sleeves have been designed to repair typical heat exchanger tube defects caused by excessive tube vibration, stress corrosion cracking, pitting or erosion. By installing a sleeve, the majority of the tube's heat transfer and flow capacity is maintained and the need to replace the heat exchanger can be delayed or eliminated. Both performance and reliability are improved. FTI typically installs heat exchanger tube sleeves using either a roll expansion or hydraulic expansion process. While roll expansion of a sleeve can be accomplished very quickly, hydraulic expansion allows sleeves to be installed deep within a tube where a roll expander cannot reach. Benefits of FTI's heat exchanger tube sleeving techniques include: - Sleeves can be positioned any where along the tube length, and for precise positioning of the sleeve eddy current techniques can be employed. - Varying sleeve lengths can be used. - Both the roll and hydraulic expansion processes are rapid and both produce joints that do not require stress relief. - Because of low leak rates and speed of installations, sleeves can be used to preventatively repair likely-to-fail tubes. - Sleeves can be used for tube stiffening and to limit leakage through tube defects. - Because of installation speed, there is minimal impact on outage schedules and budgets. FTI's recently installed heat exchanger sleeving at the Kori-3 Nuclear Power Station in conjunction with Korea Plant Service and Engineering Co., Ltd. The sleeves were installed in the 3A and 3B component cooling water heat exchangers. A total of 859 tubesheet and 68 freespan sleeves were installed in the 3A heat

Cyclotron resonance in a cathode ray tube

International Nuclear Information System (INIS)

Gherbanovschi, N.; Tanasa, M.; Stoican, O.

2002-01-01

Absorption of the RF energy by the electron beam in a cathode ray tube due to the cyclotron resonance is described. The cathode ray tube is placed within a Helmholtz coils system supplied by a sawtooth current generator. In order to generate RF field and to detect RF absorption a gate dip-meter equipped with a FET transistor is used. The bias voltage variations of the FET transistors as a function of the magnetic field are recorded. The operating point of the cathode ray tube has been chosen so that the relaxation oscillations of the detection system can be observed. (authors)

Development and validation of a simulation tool dedicated to eddy current non destructive testing of tubes

International Nuclear Information System (INIS)

Reboud, Ch.

2006-09-01

Eddy current testing (ECT) technique is widely used in industrial fields such as iron and steel industry. Dedicated simulation tools provide a great assistance for the optimisation of ECT processes. CEA and the Vallourec Research Center have collaborated in order to develop a simulation tool of ECT of tubes. The volume integral method has been chosen for the resolution of Maxwell equations in a stratified medium, in order to get accurate results with a computation time short enough to carry out optimisation or inversion procedures. A fast model has been developed for the simulation of ECT of non magnetic tubes using specific external probes. New flaw geometries have been modelled: holes and notches with flat bottom. Validations of the developments, which have been integrated to the CIVA platform, have been carried out using experimental data recorded in laboratory conditions and in. industrial conditions, successively. The integral equations derived are solved using the Galerkin variant of the method of moments with pulse functions as projection functions. In order to overcome some memory limitations, other projection functions have been considered. A new discretization scheme based on non-uniform B-Splines of degree 1 or 2 has been implemented, which constitutes an original contribution to the existing literature. The decrease of the mesh size needed to get a given accuracy on the result may lead to the simulation of more complex ECT configurations. (author)

SU-G-JeP4-13: Continuous Intra-Fractional Monitoring of the Prostate Using Dynamic KV Collimation and Tube Current Modulation

Energy Technology Data Exchange (ETDEWEB)

Parsons, D [Dalhousie Unviersity, Halifax, Nova Scotia (Canada); Robar, J [Dalhousie Unviersity, Halifax, Nova Scotia (Canada); Nova Scotia Health Authority, Halifax, NS (Canada)

2016-06-15

Purpose: The focus of this work is to improve the available kV image quality for continuous intra-fraction monitoring of the prostate. This is investigated using a novel blade collimation system enabling modulated volume-of-interest (VOI) imaging of prostate fiducial markers. Methods: A four-blade dynamic kV collimator was used to track a VOI during gantry rotation. Planar image quality was investigated as a function of collimator dimension, while maintaining the same dose to isocenter, for a 22.2 cm diameter cylindrical water phantom with a 9 mm diameter bone insert. A sample prostate anatomy was defined in the planning system, including three fiducial markers within the CTV. The VOI margin around each marker was set to be 2σ of the population covariance matrix characterizing prostate motion. DRRs were used to calculate the kV attenuation for each VOI as a function of angle. The optimal marker and tube current were determined using kV attenuation. Monte Carlo simulations were used to calculate the imaging dose to the phantom and MV scatter dose to the imaging panel. Results: Preliminary measurements show an increase in CNR by a factor of 1.3 with the VOI method, when decreasing from an 6×6 to 2×2 cm{sup 2} field. Attenuation calculations show a change in kV fluence at the detector by a factor of 21.6 with fiducial optimization; resultant tube current modulation increases maximum dose by a factor of 1.4 compared to no modulation. MV scatter contribution to the kV detector changes by approximately a factor of two over a complete gantry rotation. Conclusion: The dynamic collimation system allows single fiducial marker tracking at a very low dose, with reduction of scatter and improvement of image quality, compared to imaging the entire prostate. The approach is compatible with tube current modulation, which enables consistent image quality throughout the range of gantry rotation. This project was funded by Varian Medical Systems.

Tube plug

International Nuclear Information System (INIS)

Zafred, P. R.

1985-01-01

The tube plug comprises a one piece mechanical plug having one open end and one closed end which is capable of being inserted in a heat exchange tube and internally expanded into contact with the inside surface of the heat exchange tube for preventing flow of a coolant through the heat exchange tube. The tube plug also comprises a groove extending around the outside circumference thereof which has an elastomeric material disposed in the groove for enhancing the seal between the tube plug and the tube

Ultrasonic inspection of tube to tube plate welds

International Nuclear Information System (INIS)

Telford, D.W.; Peat, T.S.

1985-01-01

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

Template synthesis of test tube nanoparticles using non-destructive replication

International Nuclear Information System (INIS)

Wagner, Jonathan; Rodgers, David; Yao Jingyuan; Hinds, Bruce

2013-01-01

Nano test tubes are a promising delivery vehicle for a range of therapeutics, including small molecule drugs and biologics. However, current template synthesis methods of producing nano test tubes are prohibitively expensive and time consuming. Here, non-destructive template replication was used to increase nano test tube yield from porous alumina by more than a hundredfold. We demonstrate how to produce nano test tubes of several sizes and compositions, including hybrid tubes with different inner and outer surfaces for targeted surface chemistry. Nano test tubes were readily suspended and stored in aqueous solutions without the need for chemical treatment. These nano test tubes should find application as delivery vehicles for therapeutics, particularly for processive ‘bionanoreactors’ loaded with enzymes. (paper)

Reducing AC-Winding Losses in High-Current High-Power Inductors

DEFF Research Database (Denmark)

Nymand, Morten; Madawala, Udaya K.; Andersen, Michael Andreas E.

2009-01-01

Foil windings are preferable in high-current high-power inductors to realize compact designs and to reduce dc-current losses. At high frequency, however, proximity effect will cause very significant increase in ac resistance in multi-layer windings, and lead to high ac winding losses. This paper ...

Design Improvement of an X-ray Tube Applicator to Reduce ORE

International Nuclear Information System (INIS)

Lee, Juhyuk; Kim, Hyun Nam; Park, Han Beom; Cho, Sung Oh

2017-01-01

Radiation therapy has many advantages to treat cancer relative to other therapies. It does not induce scar or hair loss, and could can cover larger area than others. However, one the most critical issues about radiation therapy is shielding. Not only unnecessary exposure to patients but also those to doctors or nurses who participate in the treatment have to be lowered as possible. Occupational radiation exposure (ORE) is limited to 50 mSv per year by NCRP's recommendation. In this study, MC simulations were performed to evaluate the effective dose induced by the miniature x-ray tube. It was confirmed that when the applicator is adopted to the tube, the effective dose to doctor is less than the occupational radiation exposure limit recommended by ICRP. All assumptions used in this calculation were too highly conservative enough to have reliability. However some limitations still exist; for example, the more accurate results could be obtained if most recent version of conversion factors was used or we specified the organs irradiated and weighted the values by the radiation sensitivity.

Electronic versus traditional chest tube drainage following lobectomy

DEFF Research Database (Denmark)

Lijkendijk, Marike; Licht, Peter B; Neckelmann, Kirsten

2015-01-01

thoracic surgery, we conducted a randomized controlled trial (RCT) investigating chest tube duration and length of hospitalization. METHODS: Patients undergoing lobectomy were included in a prospective open label RCT. A strict algorithm was designed for early chest tube removal, and this decision...... was delegated to staff nurses. Data were analysed by Cox proportional hazard regression model adjusting for lung function, gender, age, BMI, video-assisted thoracic surgery (VATS) or open surgery and presence of incomplete fissure or pleural adhesions. Time was distinguished as possible (optimal) and actual.......014). CONCLUSIONS: Electronic drainage systems did not reduce chest tube duration or length of hospitalization significantly compared with traditional water seal drainage when a strict algorithm for chest tube removal was used. This algorithm allowed delegation of chest tube removal to staff nurses, and in some...

High peak power tubes and gate effect Klystrons

International Nuclear Information System (INIS)

Gerbelot, N.; Bres, M.; Faillon, G.; Buzzi, J.M.

1993-01-01

The conventional microwave tubes such as TWTs, Magnetrons, Klystrons... deliver the very high peak powers which are required by radar transmitters but more especially by many particle accelerators. In the range of a few hundred MHz to about 10 GHz, some dozen of MWs per unit are currently obtained and commercially available, according to the frequency and the pulse lengths. But peak power requirements are ever increasing, especially for the expected new linear particle acceleratores, where several hundred MWs per tube would be necessary. Also some special military transmitters begin to request GW pulses, with short pulse lengths - of course - but at nonnegligible repetition rates. Therefore several laboratories and microwave vacuum tube manufacturers have engaged - for several years - studies and development in the field of very high peak microwave power (HPM) toward two main directions: extended operation and extrapolation of the conventional tubes and devices; development of new concepts, among which the most promising are likely the high-current relativistic klystrons - that are also referred to as gate effect klystrons

Steam generator tube integrity program: Phase II, Final report

Energy Technology Data Exchange (ETDEWEB)

Kurtz, R.J.; Bickford, R.L.; Clark, R.A.; Morris, C.J.; Simonen, F.A.; Wheeler, K.R.

1988-08-01

The Steam Generator Tube Integrity Program (SGTIP) was a three phase program conducted for the US Nuclear Regulatory Commission (NRC) by Pacific Northwest Laboratory (PNL). The first phase involved burst and collapse testing of typical steam generator tubing with machined defects. The second phase of the SGTIP continued the integrity testing work of Phase I, but tube specimens were degraded by chemical means rather than machining methods. The third phase of the program used a removed-from-service steam generator as a test bed for investigating the reliability and effectiveness of in-service nondestructive eddy-current inspection methods and as a source of service degraded tubes for validating the Phase I and Phase II data on tube integrity. This report describes the results of Phase II of the SGTIP. The object of this effort included burst and collapse testing of chemically defected pressurized water reactor (PWR) steam generator tubing to validate empirical equations of remaining tube integrity developed during Phase I. Three types of defect geometries were investigated: stress corrosion cracking (SCC), uniform thinning and elliptical wastage. In addition, a review of the publicly available leak rate data for steam generator tubes with axial and circumferential SCC and a comparison with an analytical leak rate model is presented. Lastly, nondestructive eddy-current (EC) measurements to determine accuracy of defect depth sizing using conventional and alternate standards is described. To supplement the laboratory EC data and obtain an estimate of EC capability to detect and size SCC, a mini-round robin test utilizing several firms that routinely perform in-service inspections was conducted.

Steam generator tube integrity program: Phase II, Final report

International Nuclear Information System (INIS)

Kurtz, R.J.; Bickford, R.L.; Clark, R.A.; Morris, C.J.; Simonen, F.A.; Wheeler, K.R.

1988-08-01

The Steam Generator Tube Integrity Program (SGTIP) was a three phase program conducted for the US Nuclear Regulatory Commission (NRC) by Pacific Northwest Laboratory (PNL). The first phase involved burst and collapse testing of typical steam generator tubing with machined defects. The second phase of the SGTIP continued the integrity testing work of Phase I, but tube specimens were degraded by chemical means rather than machining methods. The third phase of the program used a removed-from-service steam generator as a test bed for investigating the reliability and effectiveness of in-service nondestructive eddy-current inspection methods and as a source of service degraded tubes for validating the Phase I and Phase II data on tube integrity. This report describes the results of Phase II of the SGTIP. The object of this effort included burst and collapse testing of chemically defected pressurized water reactor (PWR) steam generator tubing to validate empirical equations of remaining tube integrity developed during Phase I. Three types of defect geometries were investigated: stress corrosion cracking (SCC), uniform thinning and elliptical wastage. In addition, a review of the publicly available leak rate data for steam generator tubes with axial and circumferential SCC and a comparison with an analytical leak rate model is presented. Lastly, nondestructive eddy-current (EC) measurements to determine accuracy of defect depth sizing using conventional and alternate standards is described. To supplement the laboratory EC data and obtain an estimate of EC capability to detect and size SCC, a mini-round robin test utilizing several firms that routinely perform in-service inspections was conducted

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Reliable experimental setup to test the pressure modulation of Baerveldt Implant tubes for reducing post-operative hypotony

Science.gov (United States)

Ramani, Ajay

future to evaluate custom inserts and their effects on the pressure drop over 4 -- 6 weeks. The design requirements were: simulate physiological conditions [flow rate between 1.25 and 2.5 mul/min], evaluate small inner diameter tubes [50 and 75 mum] and annuli, and demonstrate reliability and repeatability. The current study was focused on benchmarking the experimental setup for the IOP range of 15 -- 20 mm Hg. Repeated experiments have been conducted using distilled water with configurations [diameter of tube, insert diameter, lengths of insert and tube, and flow rate] that produce pressure variations which include the 15 -- 20 mm Hg range. Two similar setups were assembled and evaluated for repeatability between the two. Experimental measurements of pressure drop were validated using theoretical calculations. Theory predicted a range of expected values by considering manufacturing and performance tolerances of the apparatus components: tube diameter, insert diameter, and the flow-rate and pressure [controlled by pump]. In addition, preliminary experiments evaluated the dissolution of suture samples in a balanced salt solution and in distilled water. The balanced salt solution approximates the eye's aqueous humor properties, and it was expected that the salt and acid would help to hydrolyze sutures much faster than distilled water. Suture samples in a balanced salt solution showed signs of deterioration [flaking] within 23 days, and distilled water samples showed only slight signs of deterioration after about 30 days. These preliminary studies indicate that future dissolution and flow experiments should be conducted using the balanced salt solution. Also, the absorbable sutures showed signs of bulk erosion/deterioration in a balanced salt solution after 14 days, which indicates that they may not be suitable as inserts in the implant tubes because flakes could block the tube entrance. Further long term studies should be performed in order to understand the effects of

Tube spacer grid for a heat-exchanger tube bundle

International Nuclear Information System (INIS)

Scheidl, H.

1976-01-01

A tube spacer grid for a heat-exchanger tube bundle is formed by an annular grid frame having a groove formed in its inner surface in which the interspaced grid bars have their ends positioned and held in interspaced relationship by short sections of tubes passed through holes axially formed in the grid frame so that the tubes are positioned between the ends of the grid bars in the grooves. The tube sections may be cut from the same tubes used to form the tube bundle. 5 claims, 3 drawing figures

Optimization of the Single Staggered Wire and Tube Heat Exchanger

Directory of Open Access Journals (Sweden)

Arsana I Made

2016-01-01

Full Text Available Wire and tube heat exchanger consists of a coiled tube, and wire is welded on the two sides of it in normal direction of the tube. Generally,wire and tube heat exchanger uses inline wire arrangement between the two sides, whereas in this study, it used staggered wire arrangement that reduces the restriction of convection heat transfer. This study performed the optimization of single staggered wire and tube heat exchanger to increase the capacity and reduce the mass of the heat exchanger. Optimization was conducted with the Hooke-Jeeves method, which aims to optimize the geometry of the heat exchanger, especially on the diameter (dw and the distance between wires (pw. The model developed to present heat transfer correlations on single staggered wire and tube heat exchanger was valid. The maximum optimization factor obtained when the diameter wire was 0.9 mm and the distance between wires (pw was 11 mm with the fref value = 1.5837. It means that the optimized design only using mass of 59,10 % and could transfer heat about 98,5 % from the basis design.

Beam tube vacuum in future superconducting proton colliders

International Nuclear Information System (INIS)

Turner, W.

1994-10-01

The beam tube vacuum requirements in future superconducting proton colliders that have been proposed or discussed in the literature -- SSC, LHC, and ELN -- are reviewed. The main beam tube vacuum problem encountered in these machines is how to deal with the magnitude of gas desorption and power deposition by synchrotron radiation while satisfying resistivity, impedance, and space constraints in the cryogenic environment of superconducting magnets. A beam tube vacuum model is developed that treats photodesorption of tightly bound H, C, and 0, photodesorption of physisorbed molecules, and the isotherm vapor pressure of H 2 . Experimental data on cold tube photodesorption experiments are reviewed and applied to model calculations of beam tube vacuum performance for simple cold beam tube and liner configurations. Particular emphasis is placed on the modeling and interpretation of beam tube photodesorpiion experiments at electron synchrotron light sources. The paper also includes discussion of the constraints imposed by beam image current heating, the growth rate of the resistive wall instability, and single-bunch instability impedance limits

Innovation in pressure tube life assessment

International Nuclear Information System (INIS)

Guler, B.; Kalenchuk, D.; Celovsky, A.

2003-01-01

The hydrogen equivalent concentration and the rate of hydrogen ingress (in particular, deuterium) in pressure tubes are important parameters that must be assessed to determine the fitness-for-service of CANDU reactors. This paper presents the latest refinement in a process referred to as 'Pressure Tube Sampling', which is the only fully qualified and proven method that allows accurate determination of both the hydrogen equivalent concentration and the rate deuterium ingress without performing an expensive fuel channel removal. Pressure Tube Sampling has evolved over the past fifteen years during which over 2,300 samples have been obtained from CANDU reactors around the globe. In-reactor sampling is the standard method for determining the hydrogen equivalent concentrations and deuterium ingress rates in CANDU reactors. Over the past fifteen years, continual improvements in the Pressure Tube Sampling process have resulted in: the capability to obtain circumferential and axial samples, reduced 'on-face' time, reduced cost, reduced dose to workers, and improved analysis accuracy. Most recently, the new Multi-Head Sampling Tool (MHST) has been developed that continues this trend by using one tool to sample at all four axial pressure tube locations in a single visit to the fuel channel, thereby further improving efficiency. In 2001 October, the MHST was successfully deployed at Wolsong 1 by AECL for Korea Hydro and Nuclear Power. The tool was delivered using their Advanced Delivery Machine (ADM) and a total of sixteen samples were obtained from four channels. A significant saving in time was achieved with a rate of one channel (four samples) being sampled every 2 1/2 hours. For a typical 10-channel campaign, this could equate to a 2 to 3 days time/saving, which is significant in terms of outage schedule, cost, and worker dose. This paper provides a description of some of the latest innovations, with specific details on site application, performance, and end results

Boiler tube failure prevention in fossil fired boilers

International Nuclear Information System (INIS)

Townsend, R.D.

1993-01-01

It is the common experience of power generating companies worldwide that the main causes of forced outages on power plant are those due to boiler tube failures on fossil units. The main reason for the large number of failures are the severe environmental conditions in fossil boilers as the effects of stress, temperature, temperature gradients, corrosion, erosion and vibration combine to produce degradation of the tube steel. Corrosion by oxidation, by combustion products and by impure boiler water can significantly reduce the tube wall thickness and result in failure of a tube many years before its designed service life. Errors can also occur in the design manufacturer, storage, operation, and maintenance of boiler tubing and the wrong material installed in a critical location can lead to premature failure. Altogether, experts in the US and UK, from many different disciplines, have identified seven broad categories of boiler tube failure mechanisms. 1 tab., 2 figs

Domain wall manipulation in magnetic nanotubes induced by electric current pulses

International Nuclear Information System (INIS)

Otálora, J A; López-López, J A; Landeros, P; Núñez, A S

2012-01-01

We propose that the injection of electric currents can be used to independently manipulate the position and chirality of vortex-like domain walls in metallic ferromagnetic nanotubes. We support this proposal upon theoretical and numerical assessment of the magnetization dynamics driven by such currents. We show that proper interplay between the tube geometry, magnitude of the electric current and the duration of a current pulse, can be used to manipulate the position, velocity and chirality of a vortex domain wall. Our calculations suggest that domain wall velocities greater than 1 km s -1 can be achieved for tube diameters of the order of 30 nm and increasing with it. We also find that the transition from steady to precessional domain wall motion occurs for very high electric current densities, of the order of 10 13 A m -2 . Furthermore, the great stability displayed by such chiral magnetic configurations, and the reduced Ohmic loses provided by the current pulses, lead to highly reproducible and efficient domain wall reversal mechanisms.

Fuel bundle to pressure tube fretting in Bruce and Darlington

Energy Technology Data Exchange (ETDEWEB)

Norsworthy, A G; Ditschun, A [Atomic Energy of Canada Ltd., Mississauga, ON (Canada)

1996-12-31

As the fuel channel elongates due to creep, the fuel string moves relative to the inlet until the fuel pads at the inboard end eventually separate from the spacer sleeve, and the fuel resides on the burnish mark of the pressure tube. The bundle is then supported in a fashion which contributes to increased levels of vibration. Those pads which (due to geometric variation) have contact loads with the pressure tube within a certain range, vibrate, and cause significant fretting on the burnish mark, and further along at the midplane of the bundle. Inspection of the pressure tubes in Bruce A, Bruce B, and Darlington has revealed fret damage up to 0.55 mm at the burnish mark and slightly lower than this at the inlet bundle midplane. To date, all fret marks have been dealt with successfully without the need for tube replacement, but a program of work has been initiated to understand the mechanism and reduce the fretting. Such understanding is necessary to guide future design changes to the fuel bundle, to guide future inspection programs, to guide maintenance programs, and for longer term strategic planning. This paper discusses how the understanding of fretting has evolved and outlines a current hypothesis for the mechanism of fretting. The role of bundle geometry, excitation forces, and reactor conditions are reviewed, along with options under consideration to mitigate damage. (author). 4 refs., 2 tabs., 13 figs.

Fuel bundle to pressure tube fretting in Bruce and Darlington

International Nuclear Information System (INIS)

Norsworthy, A.G.; Ditschun, A.

1995-01-01

As the fuel channel elongates due to creep, the fuel string moves relative to the inlet until the fuel pads at the inboard end eventually separate from the spacer sleeve, and the fuel resides on the burnish mark of the pressure tube. The bundle is then supported in a fashion which contributes to increased levels of vibration. Those pads which (due to geometric variation) have contact loads with the pressure tube within a certain range, vibrate, and cause significant fretting on the burnish mark, and further along at the midplane of the bundle. Inspection of the pressure tubes in Bruce A, Bruce B, and Darlington has revealed fret damage up to 0.55 mm at the burnish mark and slightly lower than this at the inlet bundle midplane. To date, all fret marks have been dealt with successfully without the need for tube replacement, but a program of work has been initiated to understand the mechanism and reduce the fretting. Such understanding is necessary to guide future design changes to the fuel bundle, to guide future inspection programs, to guide maintenance programs, and for longer term strategic planning. This paper discusses how the understanding of fretting has evolved and outlines a current hypothesis for the mechanism of fretting. The role of bundle geometry, excitation forces, and reactor conditions are reviewed, along with options under consideration to mitigate damage. (author). 4 refs., 2 tabs., 13 figs

Counteracting the Influence of Peer Smoking on YouTube.

Science.gov (United States)

Romer, Daniel; Jamieson, Patrick E; Jamieson, Kathleen Hall; Jones, Christopher; Sherr, Susan

2017-04-01

YouTube, a popular online site for user-generated content, is emerging as a powerful source of peer modeling of smoking. Previous research suggests that in counteracting such influence, health messages may inadvertently increase the perceived prevalence of drug use (a descriptive norm) without reducing its acceptability (injunctive norm). This research tested the ability of health messages to reduce the social acceptability of peer smoking on YouTube despite enhancing its perceived prevalence. In an online experiment with 999 adolescents, participants were randomly assigned to view one of two videos: (a) a mosaic displaying a variety of YouTube videos of adolescents smoking followed by a message about the mortality risk to those smokers, or (b) a control video on a health topic unrelated to smoking. Although exposure to the adolescent YouTube smokers increased perceived prevalence among some participants, it simultaneously increased beliefs about smoking's adverse health outcomes and negative attitudes toward smoking, effects that were associated with reductions in injunctive norms of social acceptability. Interventions that communicate the severity and scope of health risks associated with smoking may undercut the descriptive normative effects of peer modeling of smoking on social media sites such as YouTube.

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Single chest tube drainage is superior to double chest tube drainage after lobectomy: a meta-analysis.

Science.gov (United States)

Zhou, Dong; Deng, Xu-Feng; Liu, Quan-Xing; Chen, Qian; Min, Jia-Xin; Dai, Ji-Gang

2016-05-27

In this meta-analysis, we conducted a pooled analysis of clinical studies comparing the efficacy of single chest tube versus double chest tube after a lobectomy. According to the recommendations of the Cochrane Collaboration, we established a rigorous study protocol. We performed a systematic electronic search of the PubMed, Embase, Cochrane Library and Web of Science databases to identify articles to include in our meta-analysis. A literature search was performed using relevant keywords. A meta-analysis was performed using RevMan© software. Five studies, published between 2003 and 2014, including 630 patients (314 patients with a single chest tube and 316 patients with a double chest tube), met the selection criteria. From the available data, the patients using a single tube demonstrated significantly decreased postoperative pain [weighted mean difference [WMD] -0.60; 95 % confidence intervals [CIs] -0.68-- 0.52; P tube after a pulmonary lobectomy. However, there were no significant differences in postoperative complications [OR 0.91; 95 % CIs 0.57-1.44; P = 0.67] and re-drainage rates [OR 0.81; 95 % CIs 0.42-1.58; P = 0.54]. Our results showed that a single-drain method is effective, reducing postoperative pain, hospitalization times and duration of drainage in patients who undergo a lobectomy. Moreover, the single-drain method does not increase the occurrence of postoperative complications and re-drainage rates.

The Choking Game on YouTube

Directory of Open Access Journals (Sweden)

Ellen K. Defenderfer MS

2016-03-01

Full Text Available The choking game (TCG is an adolescent activity in which asphyxiation is used to obtain a “high,” occasionally resulting in seizures or death. A plethora of TCG information is available through YouTube, though this content has not been evaluated recently. The current study described TCG as portrayed in YouTube videos and compared views and ratings of TCG videos to unrelated videos. The TCG videos demonstrated diverse methods of asphyxiation, with a minority showing injury to the participants. TCG videos were less likely to be commented on or rated positively than non–choking game videos. TCG prevention videos differed significantly from actual TCG videos in the way they depicted the social context of TCG. Thus, TCG videos are accessible through YouTube, but the prevention materials available on YouTube are not accurate or representative. Accurate and educational online prevention materials should be created to decrease the occurrence of TCG.

Cotton transformation via pollen tube pathway.

Science.gov (United States)

Wang, Min; Zhang, Baohong; Wang, Qinglian

2013-01-01

Although many gene transfer methods have been employed for successfully obtaining transgenic cotton, the major constraint in cotton improvement is the limitation of genotype because the majority of transgenic methods require plant regeneration from a single transformed cell which is limited by cotton tissue culture. Comparing with other plant species, it is difficult to induce plant regeneration from cotton; currently, only a limited number of cotton cultivars can be cultured for obtaining regenerated plants. Thus, development of a simple and genotype-independent genetic transformation method is particularly important for cotton community. In this chapter, we present a simple, cost-efficient, and genotype-independent cotton transformation method-pollen tube pathway-mediated transformation. This method uses pollen tube pathway to deliver transgene into cotton embryo sacs and then insert foreign genes into cotton genome. There are three major steps for pollen tube pathway-mediated genetic transformation, which include injection of -foreign genes into pollen tube, integration of foreign genes into plant genome, and selection of transgenic plants.

Method for the detection of flaws in a tube proximate a contiguous member

International Nuclear Information System (INIS)

Holt, A.E.; Wehrmeister, A.E.; Whaley, H.L.

1979-01-01

A method for deriving the eddy current signature of a flaw in a tube proximate a contiguous member which is obscured in a composite signature of the flaw and contiguous member comprises subtracting from the composite signature a reference eddy current signature generated by scanning a reference or facsimile tube and contiguous member. The method is particularly applicable to detecting flaws in the tubes of heat exchangers of fossil fuel and nuclear power plants to enable the detection of flaws which would otherwise be obscured by contiguous members such as support plates supporting the tubes. (U.K.)

Accuracy of automatic tube compensation in new-generation mechanical ventilators.

Science.gov (United States)

Elsasser, Serge; Guttmann, Josef; Stocker, Reto; Mols, Georg; Priebe, Hans-Joachim; Haberthür, Christoph

2003-11-01

To compare performance of flow-adapted compensation of endotracheal tube resistance (automatic tube compensation, ATC) between the original ATC system and ATC systems incorporated in commercially available ventilators. Bench study. University research laboratory. The original ATC system, Dräger Evita 2 prototype, Dräger Evita 4, Puritan-Bennett 840. The four ventilators under investigation were alternatively connected via different sized endotracheal tubes and an artificial trachea to an active lung model. Test conditions consisted of two ventilatory modes (ATC vs. continuous positive airway pressure), three different sized endotracheal tubes (inner diameter 7.0, 8.0, and 9.0 mm), two ventilatory rates (15/min and 30/min), and four levels of positive end-expiratory pressure (0, 5, 10, and 15 cm H2O). Performance of tube compensation was assessed by the amount of tube-related (additional) work of breathing (WOBadd), which was calculated on the basis of pressure gradient across the endotracheal tube. Compared with continuous positive airway pressure, ATC reduced inspiratory WOBadd by 58%, 68%, 50%, and 97% when using the Evita 4, the Evita 2 prototype, the Puritan-Bennett 840, and the original ATC system, respectively. Depending on endotracheal tube diameter and ventilatory pattern, inspiratory WOBadd was 0.12-5.2 J/L with the original ATC system, 1.5-28.9 J/L with the Puritan-Bennett 840, 10.4-21.0 J/L with the Evita 2 prototype, and 10.1-36.1 J/L with the Evita 4 (difference between each ventilator at identical test situations, p ventilator (p <.025). Flow-adapted tube compensation by the original ATC system significantly reduced tube-related inspiratory and expiratory work of breathing. The commercially available ATC modes investigated here may be adequate for inspiratory but probably not for expiratory tube compensation.

Means and method for controlling the neutron output of a neutron generator tube

International Nuclear Information System (INIS)

Langford, O.M.; Peelman, H.E.

1978-01-01

Means and method are described for energizing and regulating a neutron generator tube having a target, an ion source and a replenisher. It providing a negative high voltage to the target and monitoring the target current. A constant current from a constant current source is divided into a shunt current and a replenisher current in accordence with the target current. The replenisher current is applied to the replenisher in a neutron generator tube so as to control the neutron output in accordance with the target current

Potential steam generator tube rupture in the presence of severe accident thermal challenge and tube flaws due to foreign object wear

International Nuclear Information System (INIS)

Liao, Y.; Guentay, S.

2009-01-01

This study develops a methodology to assess the probability for the degraded PWR steam generator to rupture first in the reactor coolant pressure boundary, under severe accident conditions with counter-current natural circulating high temperature gas in the hot leg and SG tubes. The considered SG tube flaws are caused by foreign object wear, which in recent years has emerged as a major inservice degradation mechanism for the new generation tubing materials. The first step develops the statistical distributions for the flaw frequency, size, and the flaw location with respect to the tube length and the tube's tubesheet position, based on data of hundreds of flaws reported in numerous SG inservice inspection reports. The next step performs thermal-hydraulic analysis using the MELCOR code and recent CFD findings to predict the thermal challenge to the degraded tubes and the tube-to-tube difference in thermal response at the SG entrance. The final step applies the creep rupture models in the Monte Carlo random walk to test the potential for the degraded SG to rupture before the surge line. The mean and range of the SG tube rupture probability can be applied to estimate large early release frequency in probabilistic safety assessment.

Impact of plasma tube wall thickness on power coupling in ICP sources

International Nuclear Information System (INIS)

Nawaz, Anuscheh; Herdrich, Georg

2009-01-01

The inductively heated plasma source at the Institute of Space Systems was investigated with respect to the wall thickness of the plasma tube using an air plasma. For this, the wall thickness of the quartz tube was reduced in steps from 2.5 to 1.25 mm. The significance of reducing the wall thickness was analyzed with respect to both the maximum allowable tube cooling power and the coupling efficiency. While the former results from thermal stresses in the tube's wall, the latter results from a minimization of magnetic field losses near the coil turns of the inductively coupled plasma (ICP) source. Analysis of the thermal stress could be validated by experimental data, i.e. the measurement of the tube cooling power when the respective tube structure failed. The coupling efficiency could be assessed qualitatively by simplified models, and the experimental data recorded show that coupling was improved far more than predicted.

Comparison of standardized uptake values measured on {sup 18}F-NaF PET/CT scans using three different tube current intensities

Energy Technology Data Exchange (ETDEWEB)

Valadares, Agnes Araujo; Woellner, Eduardo Bechtloff; Sapienza, Marcelo Tatit; Buchpiguel, Carlos Alberto, E-mail: agnesvaladares@me.com [Universidade de Sao Paulo (HC/FMUSP), Sao Paulo, SP (Brazil). Fac. de Medicina. Hospital das Clinicas; Duarte, Paulo Schiavom; Coura-Filho, George Barberio [Instituto do Cancer do Estado de Sao Paulo Octavio Frias de Oliveira (ICESP), Sao Paulo, SP (Brazil)

2015-01-15

Objective: to analyze standardized uptake values (SUVs) using three different tube current intensities for attenuation correction on {sup 18}FNaF PET/CT scans. Materials and methods: a total of 254 {sup 18}F-NaF PET/CT studies were analyzed using 10, 20 and 30 mAs. The SUVs were calculated in volumes of interest (VOIs) drawn on three skeletal regions, namely, right proximal humeral diaphysis (RH), right proximal femoral diaphysis (RF), and first lumbar vertebra (LV1) in a total of 712 VOIs. The analyses covered 675 regions classified as normal (236 RH, 232 RF, and 207 LV1). Results: mean SUV for each skeletal region was 3.8, 5.4 and 14.4 for RH, RF, and LV1, respectively. As the studies were grouped according to mAs value, the mean SUV values were 3.8, 3.9 and 3.7 for 10, 20 and 30 mAs, respectively, in the RH region; 5.4, 5.5 and 5.4 for 10, 20 and 30 mAs, respectively, in the RF region; 13.8, 14.9 and 14.5 for 10, 20 and 30 mAs, respectively, in the LV1 region. Conclusion: the three tube current values yielded similar results for SUV calculation. (author)

Status of steam generator tubing integrity at Jaslovske Bohunice NPP

International Nuclear Information System (INIS)

Cepcek, S.

1997-01-01

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

Synthesis and characterization of a novel tube-in-tube nanostructured PPy/MnO2/CNTs composite for supercapacitor

International Nuclear Information System (INIS)

Li, Juan; Que, Tingli; Huang, Jianbin

2013-01-01

Graphical abstract: A novel tube-in-tube nanostructured PPy/MnO 2 /CNTs composite have been successfully fabricated. Its inner tubules are CNTs and the outer tubules are template-synthesized PPy. Most MnO 2 nanoparticles are sandwiched between the inner and outer wall, some relatively large particles are also latched onto the outside wall of the PPy tube. The composite yields a good electrochemical reversibility through 1000 cycles’ cyclic voltammogram (CV) test and galvanostatic charge–discharge experiments at different current densities. Display Omitted Highlights: ► We fabricate a ternary organic–inorganic complex of PPy/MnO 2 /CNTs composite. ► We characterize its morphological structures and properties by several techniques. ► The composite possesses the typical tube-in-tube nanostructures. ► Most MnO 2 nanoparticles are sandwiched between the inner CNTs and outer PPy wall. ► The composite has good electrochemical reversibility for supercapacitor. -- Abstract: Ternary organic–inorganic complex of polypyrrole/manganese dioxide/carbon nanotubes (PPy/MnO 2 /CNTs) composite was prepared by in situ chemical oxidation polymerization of pyrrole in the host of inorganic matrix of MnO 2 and CNTs, using complex of methyl orange (MO)/FeCl 3 was used as a reactive self-degraded soft-template. The morphological structures of the composite were characterized by scanning electron microscopy (SEM), transmission electron microscopy (TEM), high-resolution transmission electron microscopic (HRTEM), Fourier transform infrared spectroscopy (FT-IR) and X-ray diffraction (XRD), respectively. All the results indicate that the PPy/MnO 2 /CNTs composite possesses the typical tube-in-tube nanostructures: the inner tubules are CNTs and the outer tubules are template-synthesized PPy. MnO 2 nanoparticles may either sandwich the space between the inner and outer tubules or directly latch onto the wall of the PPy tubes. The composite yields a good electrochemical

Steam generator tube integrity requirements and operating experience in the United States

International Nuclear Information System (INIS)

Karwoski, K.J.

2009-01-01

Steam generator tube integrity is important to the safe operation of pressurized-water reactors. For ensuring tube integrity, the U.S. Nuclear Regulatory Commission uses a regulatory framework that is largely performance based. This performance-based framework is supplemented with some prescriptive requirements. The framework recognizes that there are three combinations of tube materials and heat treatments currently used in the United States and that the operating experience depends, in part, on the type of material used. This paper summarizes the regulatory framework for ensuring steam generator tube integrity, it highlights the current status of steam generators, and it highlights some of the steam generator issues and challenges that exist in the United States. (author)

Flame oscillations in tubes with nonslip at the walls

Energy Technology Data Exchange (ETDEWEB)

Akkerman, V' yacheslav; Bychkov, Vitaly; Petchenko, Arkady [Institute of Physics, Umeaa University, SE-901 87 Umeaa (Sweden); Eriksson, Lars-Erik [Department of Applied Mechanics, Chalmers University of Technology, 412 96 Goeteborg (Sweden)

2006-06-15

A laminar premixed flame front propagating in a two-dimensional tube is considered with nonslip at the walls and with both ends open. The problem of flame propagation is solved using direct numerical simulations of the complete set of hydrodynamic equations including thermal conduction, diffusion, viscosity, and chemical kinetics. As a result, it is shown that flame interaction with the walls leads to the oscillating regime of burning. The oscillations involve variations of the curved flame shape and the velocity of flame propagation. The oscillation parameters depend on the characteristic tube width, which controls the Reynolds number of the flow. In narrow tubes the oscillations are rather weak, while in wider tubes they become stronger with well-pronounced nonlinear effects. The period of oscillations increases for wider tubes, while the average flame length scaled by the tube diameter decreases only slightly with increasing tube width. The average flame length calculated in the present work is in agreement with that obtained in the experiments. Numerical results reduce the gap between the theory of turbulent flames and the experiments on turbulent combustion in tubes. (author)

Fracture analysis of HFIR beam tube caused by radiation embrittlement

International Nuclear Information System (INIS)

Chang, S.J.

1994-01-01

With an attempt to estimate the neutron beam tube embrittlement condition for the Oak Ridge High Flux Isotope Reactor (HFIR), fracture mechanics calculations are carried out in this paper. The analysis provides some numerical result on how the tube has been structurally weakened. In this calculation, a lateral impact force is assumed. Numerical result is obtained on how much the critical crack size should be reduced if the beam tube has been subjected to an extended period of irradiation. It is also calculated that buckling strength of the tube is increased, not decreased, with irradiation

Design Concept of Array ECT Sensor for Steam Generator Tubing Inspection

Energy Technology Data Exchange (ETDEWEB)

Cho, Chan Hee; Lee, Tae Hun; Yoo, Hyun Ju [Korea Hydro and Nuclear Power Co. Ltd. CRI, Daejeon (Korea, Republic of)

2015-05-15

The eddy current testing, which is one of the nondestructive examination methods, is widely used for the inspection of heat exchangers including steam generator tubing in the nuclear power plant. It uses electromagnetic induction to detect flaws in conductive materials. Two types of eddy current probes are conventionally used for the inspection of steam generator tubing according to the main purpose. One is the bobbin probe technology and the other is the rotating probe. During the inspection, they have restrictions for the flaw detection or the inspection speed. An array probe can be alternative to the bobbin and rotating probes. The design concept of array coils with high sensitivity is described in this paper. It is expected that the eddy current testing using this type of array sensors may provide high detectability and resolution for flaws in steam generator tubing. Eddy current technology has some barriers for the inspection of steam generator tubing in the nuclear power plant. Bobbin probes offer poor circumferential crack detection and rotating probes are time and money consuming due to the mechanical rotation. Array probe inspection technique can replace bobbin and rotating probe techniques due to its sensitivity for flaw detection and inspection speed. In general, circular-shaped coils are considered in an array eddy current probe.

Non-destructive evaluation of stream generator tubes and pressure tubes from the PHWR reactors, using the rotating magnetic field method

International Nuclear Information System (INIS)

Premel, D.; Placko, D.; Grimberg, R.; Savin, A.

2001-01-01

This work presents a new type of eddy current transducer with a rotating magnetic field devoted to the inspection of steam generator tubes and pressure tubes from the PHWR reactors. A theoretical model has been developed that permits the calculations of the emf induced in the reception coils in the presence of the copper or magnetite deposits, anti-vibration railing and garter springs. (authors)

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Means and method for controlling the neutron output of a neutron generator tube

International Nuclear Information System (INIS)

1977-01-01

A means and method for energizing and regulating a neutron generator tube is described. It has a target, an ion source and a replenisher. A negative high voltage is applied to the target and the target current monitored. A constant current from a constant current source is divided into a shunt current and a replenisher current in accordance with the target current. The replenisher current is applied to the replenisher in a neutron generator tube so as to control the neutron output in accordance with the target current. (C.F.)

YouTube Social Network as a Business Support

OpenAIRE

Phí, Manh Hoang

2017-01-01

This bachelor thesis is focused on familiarizing the reader with the phenomenon of the YouTube social network and its possibilities for business support. The first chapter of the theoretical part introduces the reader to the basic characteristics of online marketing and its tools. The second chapter is dedicated to the YouTube social network, where the reader first learns about the key moments in YouTube history and current statistical facts. Furthermore the bachelor thesis describes the YouT...

The design of a lead-bismuth target system with a dual injection tube

International Nuclear Information System (INIS)

Cho, C.H.; Kim, Y.; Song, T.Y.; Park, W.S.

2005-01-01

A spallation target system is a key component to be developed for an accelerator driven system (ADS). It is known that a 15 ∼ 25 MW spallation target is required for a practical 1000 MWth ADS. The design of a 20 MW spallation target is very challenging because more than 60% of the beam power is deposited as heat in a small volume of the target system. In the present work, a numerical design study was performed to obtain the optimal design parameters for a 20 MW spallation target for a 1000 MW ADS. A dual injection tube was proposed for the reduction of the LBE flow rate at the target channel. The results of the present study show that a 30 cm wide proton beam with a uniform beam distribution should be adopted for the spallation target of a 20 MW power. When the dual LBE injection tube is employed, the LBE flow rate could be reduced by a factor of 4 without reducing the maximum allowable beam current. (authors)

Effects of X-ray tube parameters on thickness measure precision in X-ray profile gauge

International Nuclear Information System (INIS)

Miao Jichen; Wu Zhifang; Xing Guilai

2011-01-01

Instantaneous profile gauge technology has been widely used in metallurgy industry because it can on-line get the profile of steel strip. It has characters of high measure precision and wide measure range, but the X-ray tube parameters only can be set few different values during measurement. The relations of thickness measure precision and X-ray tube current, X-ray tube voltage were analyzed. The results show that the X-ray tube current affects the thickness measure precision and the X-ray tube voltage determines the thickness measure range. The method of estimating the X-ray current by thickness measure precision was provided in the end. This method is the base of X-ray source selection and X-ray source parameter's setting in the instantaneous profile gauge. (authors)

Development of delayed hydride cracking resistant-pressure tube

Energy Technology Data Exchange (ETDEWEB)

Kim, Young Suk; Kwon, Sang Chul; Kim, S. S.; Yim, K. S

2000-10-01

For the first time, we demonstrate that the pattern of nucleation and growth of a DHC crack is governed by the precipitation of hydrides so that the DHC velocity and K{sub IH} are determined by an angle of the cracking plane and the hydride habit plane 10.7. Since texture controls the distribution of the 10.7 habit plane in Zr-2.5Nb pressure tube, we draw a conclusion that a textural change in Zr-2.5Nb tube from a strong tangential texture to the radial texture shall increase the threshold stress intensity factor, K{sub IH}, and decrease the delayed hydride cracking velocity. This conclusion is also verified by a complimentary experiment showing a linear dependence of DHCV and K{sub IH} with an increase in the basal component in the cracking plane. On the basis of the study on the DHC mechanism and the effect of manufacturing processes on the properties of Zr-2.5Nb tube, we have established a manufacturing procedure to make pressure tubes with improved DHC resistance. The main features of the established manufacturing process consist in the two step-cold pilgering process and the intermediate heat treatment in the {alpha} + {beta} phase for Zr-2.5Nb alloy and in the {alpha} phase for Zr-1Nb-1.2Sn-0.4Fe alloy. The manufacturing of DHC resistant-pressure tubes of Zr-2.5Nb and Zr-1N-1.2Sn-0.4Fe was made in the ChMP zirconium plant in Russia under a joint research with Drs. Nikulina and Markelov in VNIINM (Russia). Zr-2.5Nb pressure tube made with the established manufacturing process has met all the specification requirements put by KAERI. Chracterization tests have been jointly conducted by VNIINM and KAERI. As expected, the Zr-2.5Nb tube made with the established procedure has improved DHC resistance compared to that of CANDU Zr-2.5Nb pressure tube used currently. The measured DHC velocity of the Zr-2.5Nb tube meets the target value (DHCV <5x10{sup -8} m/s) and its other properties also were equivalent to those of the CANDU Zr-2.5Nb tube used currently. The Zr-1Nb-1

Outgassing rate of the copper-plated beam tube for ISABELLE

International Nuclear Information System (INIS)

Hseuh, H.C.; Gaudet, E.F.

1981-01-01

The ultrahigh vacuum system of the intersecting storage accelerator, ISABELLE, will consist of two interlaced rings of stainless steel beam tubes with a circumference 2-1/2 miles each. To obtain a good heat conduction during bakeout and to reduce the resistive wall instability during beam operation, a lmm thick copper coating will be electroplated to the outer surface of this 1.5 mm thick beam tube. To minimize the beam loss due to beam-gas collision, the pressure inside the beam tube is required to be 1 x 10 -11 Torr (N 2 equivalent) or less. To achieve this ultrahigh vacuum, the outgassing rate of the 304 LN stainless steel tubes has been reduced to approx. 1 x 10 -13 Torr. l/cm 2 . sec by vacuum firing at 950 0 C for one hour. However, during acid-bath electroplating of copper, significant amount of hydrogen will be reintroduced and trapped in stainless steel which will substantially increase the outgassing rate (to approx. 2 x 10 -12 Torr . l/cm 2 sec). The outgassing characteristics of these copper-plated beam tubes are studied and discussed within the scope of diffusion and energy of activation. Methods to reduce the outgassing rate to an acceptable level (approx. 1 x 10 -13 Torr . l/cm 2 . sec) are also given

Improving the Performance of Two-Stage Gas Guns By Adding a Diaphragm in the Pump Tube

Science.gov (United States)

Bogdanoff, D. W.; Miller, Robert J.

1995-01-01

Herein, we study the technique of improving the gun performance by installing a diaphragm in the pump tube of the gun. A CFD study is carried out for the 0.28 in. gun in the Hypervelocity Free Flight Radiation (HFF RAD) range at the NASA Ames Research Center. The normal, full-length pump tube is studied as well as two pump tubes of reduced length (approximately 75% and approximately 33% of the normal length). Significant improvements in performance are calculated to be gained for the reduced length pump tubes upon the addition of the diaphragm. These improvements are identified as reductions in maximum pressures in the pump tube and at the projectile base of approximately 20%, while maintaining the projectile muzzle velocity or as increases in muzzle velocity of approximately 0.5 km/sec while not increasing the maximum pressures in the gun. Also, it is found that both guns with reduced pump tube length (with diaphragms) could maintain the performance of gun with the full length pump tube without diaphragms, whereas the guns with reduced pump tube lengths without diaphragms could not. A five-shot experimental investigation of the pump tube diaphragm technique is carried out for the gun with a pump tube length of 75% normal. The CFD predictions of increased muzzle velocity are borne out by the experimental data. Modest, but useful muzzle velocity increases (2.5 - 6%) are obtained upon the installation of a diaphragm, compared to a benchmark shot without a diaphragm.

Suppression of acoustic streaming in tapered pulse tubes

International Nuclear Information System (INIS)

Olson, J.R.; Swift, G.W.

1998-01-01

In a pulse tube cryocooler, the gas in the pulse tube can be thought of as an insulating piston, transmitting pressure and velocity from the cold heat exchanger to the hot end of the pulse tube. Unfortunately, convective heat transfer can carry heat from the hot end to the cold end and reduce the net cooling power. Here, the authors discuss one driver of such convection: steady acoustic streaming as generated by interactions between the boundary and the oscillating pressure, velocity, and temperature. Using a perturbation method, they have derived an analytical expression for the streaming in a tapered pulse tube with axially varying mean temperature in the acoustic boundary layer limit. The calculations showed that the streaming depends strongly on the taper angle, the ratio of velocity and pressure amplitudes, and the phase between the velocity and pressure, but it depends only weakly on the mean temperature profile and is independent of the overall oscillatory amplitude. With the appropriate tapering of the tube, streaming can be eliminated for a particular operating condition. Experimentally, the authors have demonstrated that an orifice pulse tube cryocooler with the calculated zero-streaming taper has more cooling power than one with either a cylindrical tube or a tapered pulse tube with twice the optimum taper angle

Contribution to the heat transfer analysis of substitute refrigerants in evaporator tubes with smooth or enhanced tube surfaces

Energy Technology Data Exchange (ETDEWEB)

Kattan, N

1997-12-31

The substitution of CFC refrigerants in refrigeration systems, heat pumps and organic Rankine cycles for heat recovery, requests a good knowledge of heat transfer properties of substitute fluids. A new test facility has been built at the Laboratory for Industrial Energy Systems (LENI) to contribute to this international effort. It consists of two sets of concentric tubes allowing either annular or inside tube convective boiling with a counter current water flow heating to be studied. A new data base including heat transfer coefficients and pressure drop measurements for four new refrigerants (R123, R134A, R402A and R404A) and three older refrigerants (R11, R12 and R502) has been collected. Flow boiling measurements covered a broad range of mass velocities, vapor qualities and heat fluxes. Some of the tests included plain tubes and others enhanced surface tubes (microfilms from Wieland) in horizontal and vertical orientations. An improved Wilson plot technique, that covers both the transition and turbulent flow regimes of the water flowing in the annular channel for the inside tube boiling tests, is proposed to overcome the severe limitations of conventional Wilson plots, to improve accuracy and to facilitate data processing. Mean flow boiling heat transfer coefficients were measured for R12 and R134A evaporating inside a horizontal plain tube and for R11 and R123 evaporating inside a horizontal plain tube. Local flow boiling heat transfer coefficients were measured for : R134A, R123, R404A and R502 evaporating inside a horizontal plain tube, for R134A and R123 evaporating inside a horizontal microfin tube and for R134 evaporating inside a vertical microfin tube. In addition microfin heat transfer augmentation relative to plain tube test data was investigated. The measured heat transfer coefficients were compared to different existing inside tube flow boiling correlations. (author) figs., tabs., refs.

Reducing iodine load in hepatic CT for patients with chronic liver disease with a combination of low-tube-voltage and adaptive statistical iterative reconstruction

Energy Technology Data Exchange (ETDEWEB)

Noda, Yoshifumi [Department of Radiology and Services, Gifu University Hospital, 1-1 Yanagido, Gifu 501-1194 (Japan); Kanematsu, Masayuki, E-mail: masa_gif@yahoo.co.jp [Department of Radiology and Services, Gifu University Hospital, 1-1 Yanagido, Gifu 501-1194 (Japan); Department of Radiology Services, Gifu University Hospital, 1-1 Yanagido, Gifu 501-1194 (Japan); Goshima, Satoshi; Kondo, Hiroshi; Watanabe, Haruo; Kawada, Hiroshi; Kawai, Nobuyuki; Tanahashi, Yukichi [Department of Radiology and Services, Gifu University Hospital, 1-1 Yanagido, Gifu 501-1194 (Japan); Miyoshi, Toshiharu R.T. [Department of Radiology Services, Gifu University Hospital, 1-1 Yanagido, Gifu 501-1194 (Japan); Bae, Kyongtae T. [Department of Radiology, University of Pittsburgh Medical Center, Pittsburgh, PA (United States)

2015-01-15

Highlights: • 80 kVp CT scanning was successfully applied to the hepatic imaging. • Iodine contrast material load was reduced to 400 mg iodine/kg. • Image quality and the detectability of HCCs were maintained. - Abstract: Purpose: To prospectively assess the effect of reduced iodine load to contrast enhancement, image quality, and detectability of hepatocellular carcinomas (HCCs) in hepatic CT with a combination of 80 kVp tube voltage setting and adaptive statistical iterative reconstruction (ASIR) technique in patients with chronic liver disease. Materials and methods: This HIPAA-compliant study was approved by our institutional review board and written informed consent was obtained in all patients. During a recent 9-month period, 170 consecutive patients (114 men and 56 women; age range, 40–85 years; mean, 67.7 years) with suspected chronic liver diseases were randomized into three CT groups according to the following iodine-load and tube-voltage protocols: 600 milligram per kilogram body weight (mg/kg) iodine load and 120 peak kilovolt (kVp) tube voltage setting (600-120 group), 500 mg/kg and 80 kVp (500-80 group), and 400 mg/kg and 80 kVp (400-80 group). Analysis of variance was conducted to evaluate differences in CT number, background noise, signal-to-noise ratio (SNR), effective dose, HCC-to-liver contrast-to-noise ratio (CNR), and figure of merit (FOM). Sensitivity, specificity, and area under the receiver-operating-characteristic curve (AUC) were compared to assess the detectability of HCCs. Results: Vascular and hepatic enhancement in the 400-80 and 500-80 groups was comparable to or greater than that in the 600-120 group (P < .05). Subjective image quality was comparable among the three groups. Sensitivity, specificity, and AUC for detecting HCCs were comparable among the groups. The effective dose was kept low (3.3–4.1 mSv) in all three groups. Conclusion: Iodine load can be reduced by 33% in CT of the liver with a combination of 80 kVp tube

Neutronics design of accelerator-driven system for power flattening and beam current reduction

International Nuclear Information System (INIS)

Nishihara, Kenji; Iwanaga, Kohei; Tsujimoto, Kazufumi; Kurata, Yuji; Oigawa, Hiroyuki; Iwasaki, Tomohiko

2008-01-01

In the present neutronics design of the Accelerator-Driven System (ADS) cooled by lead-bismuth eutectic (LBE), we investigated several methods to reduce the power peak and beam current, and estimated the temperature reductions of the cladding tube and beam window from the conventional design. The methods are adjustment of inert matrix ratio in fuel in each burn-up cycle, multiregion design in terms of pin radius or inert matrix content, and modification of the level of the beam window position and the height of the central fuel assemblies. As a result, we optimized the ADS combined with the adjustment of the inert matrix ratio in each burn-up cycle, multiregion design in terms of inert matrix content and deepened window level. The maximum temperatures of the optimized ADS at the surface of the cladding tube and the beam window were reduced by 91 and 38degC, respectively. The maximum beam current was improved from 20.3 to 15.6 mA. (author)

NEI You Tube Videos: Amblyopia

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Scale-up of counter-current chromatography: demonstration of predictable isocratic and quasi-continuous operating modes from the test tube to pilot/process scale.

Science.gov (United States)

Sutherland, Ian; Hewitson, Peter; Ignatova, Svetlana

2009-12-11

Predictable scale-up from test tube derived distribution ratios and analytical-scale sample loading optimisation is demonstrated using a model sample system of benzyl alcohol and p-cresol in a heptane:ethyl acetate:methanol:water phase system with the new 18 L Maxi counter-current chromatography centrifuge. The versatility of having a liquid stationary phase with its high loading capacity and flexible operating modes is demonstrated at two different scales by separating and concentrating target compounds using a mixture of caffeine, vanillin, naringenin and carvone using a quasi-continuous technique called intermittent counter-current extraction.

Calandria cooling structure in pressure tube reactor

International Nuclear Information System (INIS)

Hyugaji, Takenori; Sasada, Yasuhiro.

1976-01-01

Purpose: To contrive the structure of a heavy water distributing device in a pressure tube reactor thereby to reduce the variation in the cooling function thereof due to the welding deformation and installation error. Constitution: A heating water distributing plate is provided at the lower part of the upper tubular plate of a calandria tank to form a heavy water distributing chamber between both plates and a plurality of calandria tubes. Heavy water which has flowed in the upper part of the heavy water distributing plate from the heavy water inlet nozzle flows down through gaps formed around the calandria tubes, whereby the cooling of the calandria tank and the calandria tubes is carried out. In the above described calandria cooling structure, a heavy water distributing plate support is provided to secure the heavy water distributing plate and torus-shaped heavy water distributing rings are fixed to holes formed in the heavy water distributing plate penetrating through the calandria tubes thereby to form torus-shaped heavy water outlet ports each having a space. (Seki, T.)

Digital Radiography Qualification of Tube Welding

Science.gov (United States)

Carl, Chad

2012-01-01

The Orion Project will be directing Lockheed Martin to perform orbital arc welding on commodities metallic tubing as part of the Multi Purpose Crew Vehicle assembly and integration process in the Operations and Checkout High bay at Kennedy Space Center. The current method of nondestructive evaluation is utilizing traditional film based x-rays. Due to the high number of welds that are necessary to join the commodities tubing (approx 470), a more efficient and expeditious method of nondestructive evaluation is desired. Digital radiography will be qualified as part of a broader NNWG project scope.

Tube holding system

International Nuclear Information System (INIS)

Cunningham, R.C.

1978-01-01

A tube holding rig is described for the lateral support of tubes arranged in tight parcels in a heat exchanger. This tube holding rig includes not less than two tube supporting assemblies, with a space between them, located crosswise with respect to the tubes, each supporting assembly comprising a first set of parallel components in contact with the tubes, whilst a second set of components is also in contact with the tubes. These two sets of parts together define apertures through which the tubes pass [fr

Evaluation of the crack initiation of curved compact tension specimens of a Zr-2.5Nb pressure tube using the unloading compliance and direct current potential drop methods

International Nuclear Information System (INIS)

Jeong, Hyeon Cheol; Ahn, Sang Bok; Park, Joong Chul; Kim, Young Suk

2005-01-01

Zr-2.5Nb pressure tubes, carrying fuel bundles and heavy water coolant inside, degrade due to neutron irradiation and hydrogen embrittlement during their operation in heavy water reactors. The safety criterion for the Zr-2.5Nb tubes to meet is a leak-before-break (LBB) requirement. To evaluate a safety margin related to the LBB criterion, facture toughness of the pressure tubes are to be determined periodically with their operational time. For a reliable evaluation of the LBB safety criterion of the pressure tubes, it is required to precisely determine their fracture toughness. Since the fracture toughness or J of the pressure tubes is determined only by the extended crack length, it is important to reliably and precisely evaluate the advanced crack length. However, the problem lies with the detection of the crack opening point because prior plastic deformation before a start of the crack makes it difficult. The aim of this work is to evaluate which method can define the crack initiation point in the Zr- 2.5Nb compact tension specimens more precisely between the unloading compliance method with a crack opening displacement (COD) gauge and the direct current potential drop (DCPD) methods

Pressure vessels and methods of sealing leaky tubes disposed in pressure vessels

International Nuclear Information System (INIS)

Larson, G.C.

1980-01-01

This invention relates to pressure vessels and to methods of sealing leaky tubes in them and is especially applicable to pressure vessels in the form of sheet-and-tube type heat exchangers constructed with a large number of relatively small diameter tubes grouped in a bundle. To seal off a leaky tube in such a heat exchanger an explosive activated plug in the form of a hollow metal body is used, inserted at each end of the tube to be sealed. Using the arrangement of pressure vessel and associated tube sheets and the explosive activated plug method of sealing a leaky tube as described in this invention it is claimed that distortion of the adjacent tubes and the tube sheets is reduced when the explosive activated plugs are detonated. (U.K.)

Development of puncture resistance tire tube; Nirinsha no taipankusei kojo cube no kaihatsu

Energy Technology Data Exchange (ETDEWEB)

Yamagiwa, T; Nakayama, K; Kiyota, S; Tanaka, A [Honda R and D Co. Ltd., Tokyo (Japan); Makisaka, N

1997-10-01

A new tire tube with a puncture resistance function was developed. The tube is a two-chamber structure having an air chamber and a liquid chamber, and the liquid chamber at the crown-side half of the tube is filled with an anti-puncture sealant during a manufacturing process. In a market test, it was confirmed that the number of puncture cases were reduced by 90 % in comparison with conventional tire tubes by using the newly developed tube. This paper describes the structure of the tube and the characteristics of the tube rubber, and the manufacturing process and durability of the tube. 3 refs., 17 figs.

Characterization of flaws in a tube bundle mock-up for reliability studies

International Nuclear Information System (INIS)

Kupperman, D.S.; Bakhtiari, S.

1997-01-01

As part of an assessment of in-service inspection of steam generator tubes, the authors will assemble a steam generator mock-up for round robin studies and use as a test bed in evaluating emerging technologies. Progress is reported on the characterization of flaws that will be part of the mock-up. Eddy current and ultrasonic techniques are being evaluated as a means to characterize the flaws in the mock-up tubes before final assembly. Twenty Inconel 600 tubes with laboratory-grown cracks, typical of those to be used in the mock-up, were provided by Pacific Northwest National Laboratory for laboratory testing. After the tubes were inspected with eddy current and ultrasonic techniques, they were destructively analyzed to establish the actual depths, lengths, and profiles of the cracks. The analysis of the results will allow the best techniques to be used for characterizing the flaws in the mock-up tubes

Characterization of flaws in a tube bundle mock-up for reliability studies

International Nuclear Information System (INIS)