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Sample records for minimal leak rates

  1. Guidelines to achieve seals with minimal leak rates for HWR-NPR coolant system components

    International Nuclear Information System (INIS)

    Finn, P.A.

    1991-03-01

    Seal design practices that are acceptable in pressurized-water and boiling-water reactors in the United States are not usable for the Heavy Water Reactor-New Production Reactor (HWR-NPR) because of the stringent requirement on tritium control for the atmosphere within its containment building. To maintain an atmosphere in which workers do not need protective equipment, the components of the coolant system must have a cumulative leak rate less than 0.00026 L/s. Existing technology for seal systems was reviewed with regard to flange, elastomer, valve, and pump design. A technology data base for the designers of the HWR-NPR coolant system was derived from operating experience and seal development work on reactors in the United States, Canada, and Europe. This data base was then used to generate guidelines for the design of seals and/or joints for the HWR-NPR coolant system. Also discussed are needed additional research and development, as well as the necessary component qualification tests for an effective quality control program. 141 refs., 21 figs., 14 tabs

  2. Guidelines to achieve seals with minimal leak rates for HWR-NPR coolant system components

    Energy Technology Data Exchange (ETDEWEB)

    Finn, P.A.

    1991-03-01

    Seal design practices that are acceptable in pressurized-water and boiling-water reactors in the United States are not usable for the Heavy Water Reactor-New Production Reactor (HWR-NPR) because of the stringent requirement on tritium control for the atmosphere within its containment building. To maintain an atmosphere in which workers do not need protective equipment, the components of the coolant system must have a cumulative leak rate less than 0.00026 L/s. Existing technology for seal systems was reviewed with regard to flange, elastomer, valve, and pump design. A technology data base for the designers of the HWR-NPR coolant system was derived from operating experience and seal development work on reactors in the United States, Canada, and Europe. This data base was then used to generate guidelines for the design of seals and/or joints for the HWR-NPR coolant system. Also discussed are needed additional research and development, as well as the necessary component qualification tests for an effective quality control program. 141 refs., 21 figs., 14 tabs.

  3. Leak rate models and leak detection

    International Nuclear Information System (INIS)

    1992-01-01

    Leak detection may be carried out by a number of detection systems, but selection of the systems must be carefully adapted to the fluid state and the location of the leak in the reactor coolant system. Computer programs for the calculation of leak rates contain different models to take into account the fluid state before its entrance into the crack, and they have to be verified by experiments; agreement between experiments and calculations is generally not satisfactory for very small leak rates resulting from narrow cracks or from a closing bending moment

  4. Leak rate measurements and detection systems

    International Nuclear Information System (INIS)

    Kupperman, D.; Shack, W.J.; Claytor, T.

    1983-10-01

    A research program is under way to evaluate and develop improve leak detection systems. The primary focus of the work has been on acoustic emission detection of leaks. Leaks from artificial flaws, laboratory-generated IGSCCs and thermal fatigue cracks, and field-induced intergranular stress corrosion cracks (IGSCCs) from reactor piping have been examined. The effects of pressure, temperature, and leak rate and geometry on the acoustic signature are under study. The use of cross-correlation techniques for leak location and pattern recognition and autocorrelation for source discrimination is also being considered

  5. Operational tank leak detection and minimization during retrieval

    International Nuclear Information System (INIS)

    Hertzel, J.S.

    1996-03-01

    This report evaluates the activities associated with the retrieval of wastes from the single-shell tanks proposed under the initial Single-Shell Tank Retrieval System. This report focuses on minimizing leakage during retrieval by using effective leak detection and mitigating actions. After reviewing the historical data available on single-shell leakage, and evaluating current leak detection technology, this report concludes that the only currently available leak detection method which can function within the most probable leakage range is the mass balance system. If utilized after each sluicing campaign, this method should allow detection at a leakage value well below the leakage value where significant health effects occur which is calculated for each tank. Furthermore, this report concludes that the planned sequence or sluicing activities will serve to further minimize the probability and volume of leaks by keeping liquid away from areas with the greatest potential for leaking. Finally, this report identifies a series of operational responses which when used in conjunction with the recommended sluicing sequence and leak detection methods will minimize worker exposure and environmental safety health risks

  6. Evaluation of leak rate by EPRI code

    International Nuclear Information System (INIS)

    Isozaki, Toshikuni; Hashiguchi, Issei; Kato, Kiyoshi; Miyazono, Shohachiro

    1987-08-01

    From 1987, a research on the leak rate from a cracked pipe under BWR or PWR operating condition is going to be carried out at the authors' laboratory. This report describes the computed results by EPRI's leak rate code which was mounted on JAERI FACOM-M380 machine. Henry's critical flow model is used in this program. For the planning of an experimental research, the leak rate from a crack under BWR or PWR operating condition is computed, varying a crack length 2c, crack opening diameter COD and pipe diameter. The COD value under which the minimum detectable leak rate of 5 gpm is given is 0.22 mm or 0.21 mm under the BWR or PWR condition with 2c = 100 mm and 16B pipe geometry. The entire lists are shown in the appendix. (author)

  7. Experiences in integrated leak rate measurements

    International Nuclear Information System (INIS)

    Shirk, R.E.

    1982-01-01

    During a hypothetical design basis accident for nuclear power plants, the reactor containment system is relied upon to maintain radioactive exposure limits below acceptable limits. Integrated leak rate testing is a means of verifying that the leakage of radioactivity material from the reactor containment will be below allowable limits. Leakage rate computations are based on the ideal gas law. The absolute method of leakage rate testing utilizing mass point method of data analysis is recommended. Integrated leak rate testing data is obtained from pressure, drybulb temperature, dewpoint temperature, and flow measuring systems. Test data does not support the usual leakage (flow) - pressure square root relationship. The major source of potential leakage from the reactor containment is reactor containment isolation valves

  8. FFTF integrated leak rate computer system

    International Nuclear Information System (INIS)

    Hubbard, J.A.

    1987-01-01

    The Fast Flux Test Facility (FFTF) is a liquid-metal-cooled test reactor located on the Hanford site. The FFTF is the only reactor of this type designed and operated to meet the licensing requirements of the Nuclear Regulatory Commission. Unique characteristics of the FFTF that present special challenges related to leak rate testing include thin wall containment vessel construction, cover gas systems that penetrate containment, and a low-pressure design basis accident. The successful completion of the third FFTF integrated leak rate test 5 days ahead of schedule and 10% under budget was a major achievement for the Westinghouse Hanford Company. The success of this operational safety test was due in large part to a special network (LAN) of three IBM PC/XT computers, which monitored the sensor data, calculated the containment vessel leak rate, and displayed test results. The equipment configuration allowed continuous monitoring of the progress of the test independent of the data acquisition and analysis functions, and it also provided overall improved system reliability by permitting immediate switching to backup computers in the event of equipment failure

  9. Leak rate test of containment personnel lock

    International Nuclear Information System (INIS)

    Julien, J.T.; Peters, S.W.

    1988-01-01

    As part of the US NRC Containment Integrity Program, a leak rate test was performed on a full size personnel airlock for a nuclear containment building. The airlock was subjected to conditions simulating severe accident conditions. The objective of the test was to characterize the performance of airlock door seals when subjected to conditions that exceeded design. The seals tested were a double dog-ear configuration and made from EPDM E603. The data obtained from this test will be used by SNL as a benchmark for development of analytical methods. In addition to leak rate information, strain, temperature, displacements, and pressure data were measured and recorded from over 330 transducers. The test lasted approximately 60 hours. Data were recorded at regular intervals and during heating, pressurization and depressurization. The inner airlock door and bulkhead were exposed to a maximum air temperature of 850 F and a maximum air pressure of 300 psig. The airlock was originally designed for 340 F and 60 psig. Two heating and pressurization cycles were planned; one to heat to 400 F and pressurize to 300 psig, and the second to heat to 800 F and pressurize to 300 psig. No significant leakage was recorded during these two cycles. A third cycle was added to the test program. The air temperature was increased to 850 F and held at this temperature for approximately 10 hours. The inner door seal failed quickly at a pressure of 150.5 psig. The maximum leak rate was 706 SCFM

  10. Experiences with leak rate calculations methods for LBB application

    International Nuclear Information System (INIS)

    Grebner, H.; Kastner, W.; Hoefler, A.; Maussner, G.

    1997-01-01

    In this paper, three leak rate computer programs for the application of leak before break analysis are described and compared. The programs are compared to each other and to results of an HDR Reactor experiment and two real crack cases. The programs analyzed are PIPELEAK, FLORA, and PICEP. Generally, the different leak rate models are in agreement. To obtain reasonable agreement between measured and calculated leak rates, it was necessary to also use data from detailed crack investigations

  11. Experiences with leak rate calculations methods for LBB application

    Energy Technology Data Exchange (ETDEWEB)

    Grebner, H.; Kastner, W.; Hoefler, A.; Maussner, G. [and others

    1997-04-01

    In this paper, three leak rate computer programs for the application of leak before break analysis are described and compared. The programs are compared to each other and to results of an HDR Reactor experiment and two real crack cases. The programs analyzed are PIPELEAK, FLORA, and PICEP. Generally, the different leak rate models are in agreement. To obtain reasonable agreement between measured and calculated leak rates, it was necessary to also use data from detailed crack investigations.

  12. Probabilistic pipe fracture evaluations for leak-rate-detection applications

    International Nuclear Information System (INIS)

    Rahman, S.; Ghadiali, N.; Paul, D.; Wilkowski, G.

    1995-04-01

    Regulatory Guide 1.45, open-quotes Reactor Coolant Pressure Boundary Leakage Detection Systems,close quotes was published by the U.S. Nuclear Regulatory Commission (NRC) in May 1973, and provides guidance on leak detection methods and system requirements for Light Water Reactors. Additionally, leak detection limits are specified in plant Technical Specifications and are different for Boiling Water Reactors (BWRs) and Pressurized Water Reactors (PWRs). These leak detection limits are also used in leak-before-break evaluations performed in accordance with Draft Standard Review Plan, Section 3.6.3, open-quotes Leak Before Break Evaluation Proceduresclose quotes where a margin of 10 on the leak detection limit is used in determining the crack size considered in subsequent fracture analyses. This study was requested by the NRC to: (1) evaluate the conditional failure probability for BWR and PWR piping for pipes that were leaking at the allowable leak detection limit, and (2) evaluate the margin of 10 to determine if it was unnecessarily large. A probabilistic approach was undertaken to conduct fracture evaluations of circumferentially cracked pipes for leak-rate-detection applications. Sixteen nuclear piping systems in BWR and PWR plants were analyzed to evaluate conditional failure probability and effects of crack-morphology variability on the current margins used in leak rate detection for leak-before-break

  13. Experiments and calculations to leak openings and leak rates on typical piping components and systems

    International Nuclear Information System (INIS)

    Hoefler, A.; Grebner, H.

    1992-01-01

    Calculations of leak opening and leak rate for through cracks in piping components have been performed. The analyses are pre- or mostly post-calculations to experiments performed at the HDR facility under PWR operating conditions. Piping components under consideration are small diameter straight pipes with circumferential cracks, pipe bends with longitudinal or circumferential cracks and pipe branches with weldment cracks. The component are loaded by internal pressure and opening as well as closing bending moment. The finite element method and two-phase flow leak rate programs are used for the calculations. Results of the analyses are presented as J-integral values, crack opening displacements and areas and leak rates as well as comparisons to the experimental results. 6 refs., 16 figs., 2 tabs

  14. Comparison of leak opening and leak rate calculations to HDR experimental results

    International Nuclear Information System (INIS)

    Grebner, H.; Hoefler, A.; Hunger, H.

    1993-01-01

    During the last years a number of calculations of leak opening and leak rate for through cracks in piping components have been performed. Analyses are pre- or mostly post-calculations to experiments performed at the HDR facility under PWR operating conditions. Piping components under consideration were small diameter straight pipes with circumferential cracks, pipe bends with longitudinal or circumferential cracks and pipe branches with weldment cracks. The components were loaded by internal pressure and opening as well as closing bending moment. The finite element method and two-phase flow leak rate programs were used for the calculations. Results of the analyses are presented as J-integral values, crack opening displacements and areas and leak rates as well as comparisons to the experimental results

  15. Study on the leak rate test for HANARO reactor building

    International Nuclear Information System (INIS)

    Choi, Y. S.; Kim, Y. K.; Kim, M. J.; Park, J. M.; Woo, J. S.

    2002-01-01

    The reactor building of HANARO adopts the confinement concept, which allows a certain amount of air leakage. In order to restrict the air leakage through the confinement boundary, negative pressure of at least 2.5 mmWG is maintained in normal operating condition while maintaining 25 mmWG of negative pressure in abnormal condition, the inside air filtered by a train of charcoal filter is released to the atmosphere through the stack. In this situation, if the emergency ventilation system is not operable, the reactor building is isolated from the outside then the trapped air inside will be leaked out through the building by ground release concept. As the leak rate may be affected by an effect of wind velocity outside the reactor building, the air tightness of confinement should be maintained to limit the leak rate below the allowable value. The local leak rate test method was used since the beginning of the commissioning until July 1999. However it has been pointed out as a defect that the method is so susceptible to the change of temperature and atmospheric pressure during testing. For more accurate leak rate testing, we have introduced a new test method. We have periodically carried out the new leak rate testing and the results indicate that the bad effect by the temperature and atmospheric pressure change is considerably reduced, which gives more stable leak rate measurement

  16. LEAK: A source term generator for evaluating release rates from leaking vessels

    International Nuclear Information System (INIS)

    Clinton, J.H.

    1994-01-01

    An interactive computer code for estimating the rate of release of any one of several materials from a leaking tank or broken pipe leading from a tank is presented. It is generally assumed that the material in the tank is liquid. Materials included in the data base are acetonitrile, ammonia, carbon tetrachloride, chlorine, chlorine trifluoride, fluorine, hydrogen fluoride, nitric acid, nitrogen tetroxide, sodium hydroxide, sulfur hexafluoride, sulfuric acid, and uranium hexafluoride. Materials that exist only as liquid and/or vapor over expected ranges of temperature and pressure can easily be added to the data base file. The Fortran source code for LEAK and the data file are included with this report

  17. Achieving low anastomotic leak rates utilizing clinical perfusion assessment.

    Science.gov (United States)

    Kream, Jacob; Ludwig, Kirk A; Ridolfi, Timothy J; Peterson, Carrie Y

    2016-10-01

    Anastomotic leak after colorectal resection increases morbidity, mortality, and in the setting of cancer, increases recurrences rates and reduces survival odds. Recent reports suggest that fluorescence evaluation of perfusion after colorectal anastomosis creation is associated with low anastomotic leak rates (1.4%). The purpose of this work was to evaluate whether a similar low anastomotic leak rate after left-sided colorectal resections could be achieved using standard assessment of blood flow to the bowel ends. We performed a retrospective chart review at an academic tertiary referral center, evaluating 317 consecutive patients who underwent a pelvic anastomosis after sigmoid colectomy, left colectomy, or low anterior resection. All operations were performed by a single surgeon from March 2008 to January 2015 with only standard clinical measures used to assess perfusion to the bowel ends. The primary outcome measure was the anastomotic leak rate as diagnosed by clinical symptoms, exam, or routine imaging. The average patient age was 59.7 years with an average body mass index of 28.8 kg/m(2). Rectal cancer (128, 40.4%) was the most common indication for operation while hypertension (134, 42.3%) was the most common comorbidity. In total, 177 operations were laparoscopic (55.8%), 13 were reoperative resections (4.1%), and 108 were protected with a loop ileostomy (34.1%). Preoperative chemotherapy was administered to 25 patients (7.9%) while preoperative chemo/radiation was administered to 64 patients (20.2%). The anastomotic leak rate was 1.6% (5/317). Our data suggests that standard, careful evaluation of adequate blood flow via inspection and confirmation of pulsatile blood flow to the bowel ends and meticulous construction of the colorectal or coloanal anastomoses can result in very low leak rates, similar to the rate reported when intraoperative imaging is used to assess perfusion. Copyright © 2016 Elsevier Inc. All rights reserved.

  18. Integrated leak rate test results of JOYO reactor containment vessel

    International Nuclear Information System (INIS)

    Tamura, M.; Endo, J.

    1982-02-01

    Integrated leak rate tests of JOYO after the reactor coolant system had been filled with sodium have been performed two times since 1978 (February 1978 and December 1979). The tests were conducted with the in-containment sodium systems, primary argon cover gas system and air conditioning systems operating. Both the absolute pressure method and the reference chamber method were employed during the test. The results of both tests confirmed the functioning of the containment vessel, and leak rate limits were satisfied. In Addition, the adequancy of the test instrumentation system and the test method was demonstrated. Finally the plant conditions required to maintain reasonable accuracy for the leak rate testing of LMFBR were established. In this paper, the test conditions and the test results are described. (author)

  19. Leak-rate qualification of the FFTF control area

    International Nuclear Information System (INIS)

    Billings, M.P.; Swenson, L.D.

    1983-06-01

    Positive experience with the Fast Flux Test Facility (FFTF) Control Area boundary has demonstrated that strigent requirements for reactor control room leak-tightness can be met and maintained. Guidance contained in 10CFR50, Appendix A, Criteria 4 and 19, and Regulatory Guides 1.78 and 1.95 provided criteria for control room habitability, to provide safe, central control of the FFTF plant under normal and accident conditions. A leak rate criterion of 178 scfm for the approximate 53,000 cu. ft. Volume of the Control Area was established for the limiting condition of airborne sodium oxide aerosols from a postulated fire in one of the three secondary sodium loops. Numerous tests utilizing a variety of leak identification techniques were conducted

  20. Study on the Measurement of Valve Leak Rate Using Acoustic Emission Technology

    International Nuclear Information System (INIS)

    Lee, Sang-Guk; Park, Jong-Hyuck; Yoo, Keun-Bae; Lee, Sun-Ki; Hong, Sung-Yull

    2006-01-01

    This study is to estimate the feasibility of acoustic emission(AE) method for the internal leak from the valves. In this study, 4 inch ball water valve leak tests using three different leak path and various leak rates were performed in order to analyze AE properties when leaks arise in valve seat. As a result of leak test for specimens simulated valve seat, we conformed that leak sound amplitude increased in proportion to the increase of leak rate, and leak rates were plotted versus peak acoustic amplitudes recorded within those two narrow frequency bands on each spectrum plot. The resulting plots of leak rate versus peak AE amplitude were the primary basis for determining the feasibility of quantifying leak acoustically. The large amount of data attained also allowed a favorable investigation of the effects of different leak paths, leak rates, pressure differentials and AE sensors on the AE amplitude spectrum. From the experimental results, it was suggested that the AE method for monitoring of leak was feasible. This paper describes quantitative measurements of fluid valve leak rates by the analysis of AE. Experimental apparatus were fabricated to accept a variety of leaking water valves in order to determine what characteristics of AE signal change with leak rate. The data for each valve were generated by varying the leak rate and recording the time averaged amplitude of AE versus frequency. Leak rates were varied by modifying the valve seating surfaces in ways designed to simulate actual defects observed in service. Most of the data analysis involved plotting the leak rate versus signal amplitude at a specific frequency to determine how well the two variables correlate in terms of accuracy, resolution, and repeatability

  1. Evaluation of methodologies for the calculation of leak rates for pressure retaining components with crack-like leaks

    International Nuclear Information System (INIS)

    Sievers, Juergen; Heckmann, Klaus; Blaesius, Christoph

    2015-06-01

    For the demonstration of break preclusion for pressure retaining components in nuclear power plants, the nuclear safety standard KTA 3206 determines also the requirements for the leak-before-break verification. For this procedure, it has to be ensured that a wall-penetrating crack is subcritical with respect to instable growth, and that the resulting leakage under stationary operation conditions can be detected by a leak detection system. Within the scope of the project 3613R01332 analyses with respect to conservative estimates of the leak rates in case of detections regarding break preclusion were performed by means of leak rate models being available at GRS. For this purpose, conservative assumptions in the procedure were quantified by comparative calculations concerning selected leak rate experiments and the requirements regarding the determination of leak rates indicated in the KTA 3206 were verified and specified. Moreover, the models were extended and relevant recommendations for the calculation procedure were developed. During the investigations of leak rate tests the calculation methods were validated, qualified by means of both examples indicated in KTA 3206 and applied to a postulated leak accident in the cooling circuit of a PWR. For the calculation of leak rates several simplified solution methods which are included in the GRS program WinLeck were applied, and for the simulation of a leak accident the large-scale programs ANSYS Mechanical and ATHLET (thermohydraulics program developed by GRS) were used. When applying simplified methods for the calculation of leak rates using the limiting curve for the friction factor which has been derived during the project and which is included in the KTA 3206 attention has to be paid to the fact that in case of small flow lengths the entrance loss can dominate compared to the friction loss. However, the available data do not suffice in order to make a quantitative statement with respect to limits of applicability

  2. Measurement for the Leak Rate enhanced by a Improved Method

    International Nuclear Information System (INIS)

    Bae, Sang-Hoon; Choi, Young-San; Kim, Young-Ki; Lee, Yong-Sub; Jung, Hoan-Sung

    2007-01-01

    The leak rate measurement of the HANARO such as a research reactor that adopts a confinement concept for a reactor hall is very important one during a period inspection. This test verifies whether the reactor building could maintain the negative pressure or not when radiation is perceived by abnormal accidents. Of course, this may not cause a problem in a reactor operation only if it can satisfy the design requirement, but it is necessary to have some margin of a limitation value because a reactor hall should be managed more conservatively than the design reference. To meet the requirements of this strict design condition, previous method was changed to a new type of test with more stable and robust measuring method. The new leak rate measurement method is briefly introduced and the merits of this proposed method are shown through the data analyzed for last 3 years

  3. Pipe fracture evaluations for leak-rate detection: Probabilistic models

    International Nuclear Information System (INIS)

    Rahman, S.; Wilkowski, G.; Ghadiali, N.

    1993-01-01

    This is the second in series of three papers generated from studies on nuclear pipe fracture evaluations for leak-rate detection. This paper focuses on the development of novel probabilistic models for stochastic performance evaluation of degraded nuclear piping systems. It was accomplished here in three distinct stages. First, a statistical analysis was conducted to characterize various input variables for thermo-hydraulic analysis and elastic-plastic fracture mechanics, such as material properties of pipe, crack morphology variables, and location of cracks found in nuclear piping. Second, a new stochastic model was developed to evaluate performance of degraded piping systems. It is based on accurate deterministic models for thermo-hydraulic and fracture mechanics analyses described in the first paper, statistical characterization of various input variables, and state-of-the-art methods of modem structural reliability theory. From this model. the conditional probability of failure as a function of leak-rate detection capability of the piping systems can be predicted. Third, a numerical example was presented to illustrate the proposed model for piping reliability analyses. Results clearly showed that the model provides satisfactory estimates of conditional failure probability with much less computational effort when compared with those obtained from Monte Carlo simulation. The probabilistic model developed in this paper will be applied to various piping in boiling water reactor and pressurized water reactor plants for leak-rate detection applications

  4. Estimation of Leak Rate from the Emergency Pump Well in L-Area Complex Basin

    International Nuclear Information System (INIS)

    Duncan, A

    2005-01-01

    This report provides an estimate of the leak rate from the emergency pump well in L-basin that is to be expected during an off-normal event. This estimate is based on expected shrinkage of the engineered grout (i.e., controlled low strength material) used to fill the emergency pump well and the header pipes that provide the dominant leak path from the basin to the lower levels of the L-Area Complex. The estimate will be used to provide input into the operating safety basis to ensure that the water level in the basin will remain above a certain minimum level. The minimum basin water level is specified to ensure adequate shielding for personnel and maintain the ''as low as reasonably achievable'' concept of radiological exposure. The need for the leak rate estimation is the existence of a gap between the fill material and the header pipes, which penetrate the basin wall and would be the primary leak path in the event of a breach in those pipes. The gap between the pipe and fill material was estimated based on a full scale demonstration pour that was performed and examined. Leak tests were performed on full scale pipes as a part of this examination. Leak rates were measured to be on the order of 0.01 gallons/minute for completely filled pipe (vertically positioned) and 0.25 gallons/minute for partially filled pipe (horizontally positioned). This measurement was for water at 16 feet head pressure and with minimal corrosion or biofilm present. The effect of the grout fill on the inside surface biofilm of the pipes is the subject of a previous memorandum

  5. Burst pressure and leak rate from fretted SG tubes

    International Nuclear Information System (INIS)

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

    2005-01-01

    Steam generator(SG) tubes of a pressurized water reactor(PWR) have suffered from various types of corrosion, such as pitting, wastage and stress corrosion cracking (SCC) on both the primary and secondary side. Recently, fretting/wear degradation at the tube support region has been reported in some Korean nuclear power plants. In order to prevent the primary coolant from leaking to the secondary side, the tubes are repaired by a sleeving or plugging. It is important to establish the repair criteria to assure a reactor integrity and yet maintain the plugging ratio within the limits needed for an efficient operation. The objective of the burst test is to obtain a relationship between the burst/leak rate and the shape of the fretted flaws machined with an electro discharge machining (EDM)

  6. RCS Leak Rate Calculation with High Order Least Squares Method

    International Nuclear Information System (INIS)

    Lee, Jeong Hun; Kang, Young Kyu; Kim, Yang Ki

    2010-01-01

    As a part of action items for Application of Leak before Break(LBB), RCS Leak Rate Calculation Program is upgraded in Kori unit 3 and 4. For real time monitoring of operators, periodic calculation is needed and corresponding noise reduction scheme is used. This kind of study was issued in Korea, so there have upgraded and used real time RCS Leak Rate Calculation Program in UCN unit 3 and 4 and YGN unit 1 and 2. For reduction of the noise in signals, Linear Regression Method was used in those programs. Linear Regression Method is powerful method for noise reduction. But the system is not static with some alternative flow paths and this makes mixed trend patterns of input signal values. In this condition, the trend of signal and average of Linear Regression are not entirely same pattern. In this study, high order Least squares Method is used to follow the trend of signal and the order of calculation is rearranged. The result of calculation makes reasonable trend and the procedure is physically consistence

  7. The discussion on a new measure method of radon chamber leak rate

    International Nuclear Information System (INIS)

    Zhang Junkui; Tang Bing

    2010-01-01

    Radon chamber is the third standard radon source. The leak rate is the key parameter for the radon chamber to naturally and safely operate. One way, that measure the leak rate is introduced. The experience result is that the way is simple and veracious to measure the leak rate. (authors)

  8. Quantitative study of sniffer leak rate and pressure drop leak rate of liquid nitrogen panels of SST-1 tokamak

    Science.gov (United States)

    Pathan, F. S.; Khan, Z.; Semwal, P.; Raval, D. C.; Joshi, K. S.; Thankey, P. L.; Dhanani, K. R.

    2008-05-01

    Steady State Super-conducting (SST-1) Tokamak is in commissioning stage at Institute for Plasma Research. Vacuum chamber of SST-1 Tokamak consists of 1) Vacuum vessel, an ultra high vacuum (UHV) chamber, 2) Cryostat, a high vacuum (HV) chamber. Cryostat encloses the liquid helium cooled super-conducting magnets (TF and PF), which require the thermal radiation protection against room temperature. Liquid nitrogen (LN2) cooled panels are used to provide thermal shield around super-conducting magnets. During operation, LN2 panels will be under pressurized condition and its surrounding (cryostat) will be at high vacuum. Hence, LN2 panels must have very low leak rate. This paper describes an experiment to study the behaviour of the leaks in LN2 panels during sniffer test and pressure drop test using helium gas.

  9. Quantitative study of sniffer leak rate and pressure drop leak rate of liquid nitrogen panels of SST-1 tokamak

    Energy Technology Data Exchange (ETDEWEB)

    Pathan, F S; Khan, Z; Semwal, P; Raval, D C; Joshi, K S; Thankey, P L; Dhanani, K R [Institute for Plasma Research, Bhat, Gandhinagar - 382 428, Gujarat (India)], E-mail: firose@ipr.res.in

    2008-05-01

    Steady State Super-conducting (SST-1) Tokamak is in commissioning stage at Institute for Plasma Research. Vacuum chamber of SST-1 Tokamak consists of 1) Vacuum vessel, an ultra high vacuum (UHV) chamber, 2) Cryostat, a high vacuum (HV) chamber. Cryostat encloses the liquid helium cooled super-conducting magnets (TF and PF), which require the thermal radiation protection against room temperature. Liquid nitrogen (LN2) cooled panels are used to provide thermal shield around super-conducting magnets. During operation, LN{sub 2} panels will be under pressurized condition and its surrounding (cryostat) will be at high vacuum. Hence, LN{sub 2} panels must have very low leak rate. This paper describes an experiment to study the behaviour of the leaks in LN{sub 2} panels during sniffer test and pressure drop test using helium gas.

  10. Quantitative study of sniffer leak rate and pressure drop leak rate of liquid nitrogen panels of SST-1 tokamak

    International Nuclear Information System (INIS)

    Pathan, F S; Khan, Z; Semwal, P; Raval, D C; Joshi, K S; Thankey, P L; Dhanani, K R

    2008-01-01

    Steady State Super-conducting (SST-1) Tokamak is in commissioning stage at Institute for Plasma Research. Vacuum chamber of SST-1 Tokamak consists of 1) Vacuum vessel, an ultra high vacuum (UHV) chamber, 2) Cryostat, a high vacuum (HV) chamber. Cryostat encloses the liquid helium cooled super-conducting magnets (TF and PF), which require the thermal radiation protection against room temperature. Liquid nitrogen (LN2) cooled panels are used to provide thermal shield around super-conducting magnets. During operation, LN 2 panels will be under pressurized condition and its surrounding (cryostat) will be at high vacuum. Hence, LN 2 panels must have very low leak rate. This paper describes an experiment to study the behaviour of the leaks in LN 2 panels during sniffer test and pressure drop test using helium gas

  11. Leak rate analysis of the Westinghouse Reactor Coolant Pump

    International Nuclear Information System (INIS)

    Boardman, T.; Jeanmougin, N.; Lofaro, R.; Prevost, J.

    1985-07-01

    An independent analysis was performed by ETEC to determine what the seal leakage rates would be for the Westinghouse Reactor Coolant Pump (RCP) during a postulated station blackout resulting from loss of ac electric power. The object of the study was to determine leakage rates for the following conditions: Case 1: All three seals function. Case 2: No. 1 seal fails open while Nos. 2 and 3 seals function. Case 3: All three seals fail open. The ETEC analysis confirmed Westinghouse calculations on RCP seal performance for the conditions investigated. The leak rates predicted by ETEC were slightly lower than those predicted by Westinghouse for each of the three cases as summarized below. Case 1: ETEC predicted 19.6 gpm, Westinghouse predicted 21.1 gpm. Case 2: ETEC predicted 64.7 gpm, Westinghouse predicted 75.6 gpm. Case 3: ETEC predicted 422 gpm, Westinghouse predicted 480 gpm. 3 refs., 22 figs., 6 tabs

  12. Estimation of leak rate through circumferential cracks in pipes in nuclear power plants

    Directory of Open Access Journals (Sweden)

    Jai Hak Park

    2015-04-01

    Full Text Available The leak before break (LBB concept is widely used in designing pipe lines in nuclear power plants. According to the concept, the amount of leaking liquid from a pipe should be more than the minimum detectable leak rate of a leak detection system before catastrophic failure occurs. Therefore, accurate estimation of the leak rate is important to evaluate the validity of the LBB concept in pipe line design. In this paper, a program was developed to estimate the leak rate through circumferential cracks in pipes in nuclear power plants using the Henry–Fauske flow model and modified Henry–Fauske flow model. By using the developed program, the leak rate was calculated for a circumferential crack in a sample pipe, and the effect of the flow model on the leak rate was examined. Treating the crack morphology parameters as random variables, the statistical behavior of the leak rate was also examined. As a result, it was found that the crack morphology parameters have a strong effect on the leak rate and the statistical behavior of the leak rate can be simulated using normally distributed crack morphology parameters.

  13. NEK containment integrated leak rate test at full pressure

    International Nuclear Information System (INIS)

    Skaler, F.; Planinc, V.; Gregoric, D.; Cicvaric, D.

    1999-01-01

    NPP Krsko is a Pressure Water Reactor (PWR) Plant which has four barriers to prevent release of radioactive fission products. These four barriers are following: Fuel itself, Fuel Clad, Reactor Coolant System and Containment Building. Containment is the last barrier which can prevent release of fission product when other barriers have been already broken. To find out the real condition of containment vessel and to prove its ability of withstanding increased parameters during accident we have to perform Containment Integrated Leak Rate Test at least three times in every ten years of operation. CILRT 1999 in NPP Krsko was completely performed following regulation of 10CFR50 App. J Option A and ANSI/ANS 56.8-1987. The main goal of CILRT is to prove that the leakage of containment pathways and wall structures are within limits prescribed in Technical Specifications by pressurization of containment building above peak accident pressure Pa and measuring the mass changes of air using Ideal Gas Law.(author)

  14. Differential measurement of low level HTO and HT leak rates

    International Nuclear Information System (INIS)

    Sheehan, W.E.; Muldoon, K.M.

    1976-08-01

    Leak rates of 5 x 10 -17 cm 3 /sec and greater can be measured by a very simple technique that will also differentiate tritium oxide (HTO) from tritium gas (HT). Because of the much greater health hazard of tritium oxide (200 to 1), the determination of chemical form is significant. The method involves flushing a gas collection chamber, containing the item being measured, with dry air. The flushed air is passed through an ethylene glycol bubbler which removes only the HTO. The outlet of the ethylene glycol bubbler is connected to a heated (400 0 C) palladium sponge catalyst which converts the HT to HTO and then to a second ethylene glycol bubbler for collection of the oxidized tritium gas. Liquid scintillation (p-dioxane base) counting solution is added directly to the bubblers and counted for tritium in a Liquid Scintillation Spectrometer. Advantages, method validation, operational experience, and data obtained by this technique are discussed. The sensitivity of the method is dependent on the time allowed between bubbler changes, the liquid scintillation spectrometer counting efficiency, background, and counting times employed

  15. Estimation of Leak Rate Through Cracks in Bimaterial Pipes in Nuclear Power Plants

    Directory of Open Access Journals (Sweden)

    Jai Hak Park

    2016-10-01

    Full Text Available The accurate estimation of leak rate through cracks is crucial in applying the leak before break (LBB concept to pipeline design in nuclear power plants. Because of its importance, several programs were developed based on the several proposed flow models, and used in nuclear power industries. As the flow models were developed for a homogeneous pipe material, however, some difficulties were encountered in estimating leak rates for bimaterial pipes. In this paper, a flow model is proposed to estimate leak rate in bimaterial pipes based on the modified Henry–Fauske flow model. In the new flow model, different crack morphology parameters can be considered in two parts of a flow path. In addition, based on the proposed flow model, a program was developed to estimate leak rate for a crack with linearly varying cross-sectional area. Using the program, leak rates were calculated for through-thickness cracks with constant or linearly varying cross-sectional areas in a bimaterial pipe. The leak rate results were then compared and discussed in comparison with the results for a homogeneous pipe. The effects of the crack morphology parameters and the variation in cross-sectional area on the leak rate were examined and discussed.

  16. On the possibilities for efficient simulation of leak rates through SG tubes

    International Nuclear Information System (INIS)

    Sorsek, I.; Cizelj, L.

    1995-01-01

    In this paper, the problem of predicting excessive leak rates through the through wall cracks in tubes at the tube - tube support plate intersections is discussed in some detail. Basically, we are able to define the leak rate through an individual defect. On the steam generator level, which actually means the sum of all individual leak rates, a new approach is introduced. The main characteristic of the new approach is seeking for a probability of exceeding the allowable leak rate rather than estimating more or less conservative highest expected leak rate value. This however introduces extensive computational effort which practically prevents the use of direct Monte Carlo simulations. Some possibilities to reduce the computational effort are discussed and their preliminary results compared. Also, some exact solutions were found and compared with numerical solutions achieved with the first order reliability method. Directions for future work in this important topic are given. (author)

  17. The calculation of coolant leak rate through the cracks using RELAP5 code

    International Nuclear Information System (INIS)

    Krungeleviciute, V.; Kaliatka, A.

    2001-01-01

    For reason to choose method of leak detection first of all it is necessary to perform evaluating thermal-hydraulic calculations. These calculations allow to determine flow rate of discharged coolant. For coolant leak rate calculations through possible cracks in Ignalina NPP pipes SQUIRT and RELAP5 thermal-hydraulic codes were used. SQUIRT is well known as computer program that predicts the leakage for cracked pipes in NPP. As this code calculates only water (at subcooled or saturated conditions) leak rate, RELAP5 code model, that calculates water and steam leak rate, was created. For model validation comparison of SQUIRT, RELAP5 and experimental results was performed. Analysis shows RELAP5 code model suitability for calculations of leak through through-wall cracks in pipes. (author)

  18. Phylogenetic differences of mammalian basal metabolic rate are not explained by mitochondrial basal proton leak.

    Science.gov (United States)

    Polymeropoulos, E T; Heldmaier, G; Frappell, P B; McAllan, B M; Withers, K W; Klingenspor, M; White, C R; Jastroch, M

    2012-01-07

    Metabolic rates of mammals presumably increased during the evolution of endothermy, but molecular and cellular mechanisms underlying basal metabolic rate (BMR) are still not understood. It has been established that mitochondrial basal proton leak contributes significantly to BMR. Comparative studies among a diversity of eutherian mammals showed that BMR correlates with body mass and proton leak. Here, we studied BMR and mitochondrial basal proton leak in liver of various marsupial species. Surprisingly, we found that the mitochondrial proton leak was greater in marsupials than in eutherians, although marsupials have lower BMRs. To verify our finding, we kept similar-sized individuals of a marsupial opossum (Monodelphis domestica) and a eutherian rodent (Mesocricetus auratus) species under identical conditions, and directly compared BMR and basal proton leak. We confirmed an approximately 40 per cent lower mass specific BMR in the opossum although its proton leak was significantly higher (approx. 60%). We demonstrate that the increase in BMR during eutherian evolution is not based on a general increase in the mitochondrial proton leak, although there is a similar allometric relationship of proton leak and BMR within mammalian groups. The difference in proton leak between endothermic groups may assist in elucidating distinct metabolic and habitat requirements that have evolved during mammalian divergence.

  19. Supporting information for the estimation of plutonium oxide leak rates through very small apertures

    International Nuclear Information System (INIS)

    Schwendiman, L.C.

    1977-01-01

    Information is presented from which an estimate can be made of the release of plutonium oxide from shipping containers. The leak diameter is estimated from gas leak tests of the container and an estimate is made of gas leak rate as a function of pressure over the time of interest in the accident. These calculations are limited in accuracy because of assumptions regarding leak geometry and the basic formulations of hydrodynamic flow for the assumed conditions. Sonic flow is assumed to be the limiting gas flow rate. Particles leaking from the air space above the powder will be limited by the low availability of particles due to rapid settling, the very limited driving force (pressure buildup) during the first minute, and the deposition in the leak channel. Equations are given to estimate deposition losses. Leaks of particles occurring below the level of the bulk powder will be limited by mechanical interference when leaks are of dimension smaller than particle sizes present. Some limiting cases can be calculated. When the leak dimension is large compared to the particle sizes present, maximum particle releases can be estimated, but will be very conservative

  20. Urine leak in minimally invasive partial nephrectomy: analysis of risk factors and role of intraoperative ureteral catheterization

    Directory of Open Access Journals (Sweden)

    Homayoun Zargar

    2014-12-01

    Full Text Available Purpose To investigate risk factors for urine leak in patients undergoing minimally invasive partial nephrectomy (MIPN and to determine the role of intraoperative ureteral catheterization in preventing this postoperative complication. Materials and Methods MIPN procedures done from September 1999 to July 2012 at our Center were reviewed from our IRB-approved database. Patient and tumor characteristics, operative techniques and outcomes were analyzed. Patients with evidence of urine leak were identified. Outcomes were compared between patients with preoperative ureteral catheterization (C-group and those without (NC-group. Univariable and multivariable analyses were performed to identify factors predicting postoperative urine leak. Results A total of 1,019 cases were included (452 robotic partial nephrectomy cases and 567 laparoscopic partial nephrectomy cases. Five hundred twenty eight patients (51.8% were in the C-group, whereas 491 of them (48.2% in the NC-group. Urine leak occurred in 31(3% cases, 4.6% in the C-group and 1.4% in the NC-group (p<0.001. Tumors in NC-group had significantly higher RENAL score, shorter operative and warm ischemic times. On multivariable analysis, tumor proximity to collecting system (OR=9.2; p<0.01, surgeon’s early operative experience (OR=7.8; p<0.01 and preoperative moderate to severe CKD (OR=3.1; p<0.01 significantly increased the odds of the occurrence of a postoperative urine leak. Conclusion Clinically significant urine leak after MIPN in a high volume institution setting is uncommon. This event is more likely to occur in cases of renal masses that are close to the collecting system, in patients with preoperative CKD and when operating surgeon is still in the learning curve for the procedure. Our findings suggest that routine intraoperative ureteral catheterization during MIPN does not reduce the probability of postoperative urine leak. In addition, it adds to the overall operative time.

  1. Leak rate measurements on bimetallic transition samples for ILC cryomodules

    International Nuclear Information System (INIS)

    Budagov, Yu.; Chernikov, A.; Sabirov, B.

    2008-01-01

    The results of leak test of bimetallic (titanium-stainless steel) transition elements produced by explosion welding are presented. Vacuum and high-pressure tests of the sample for leakage were carried out at room temperature and liquid nitrogen temperature. Similar tests were also carried out under thermal cycling conditions

  2. Using An Adapter To Perform The Chalfant-Style Containment Vessel Periodic Maintenance Leak Rate Test

    International Nuclear Information System (INIS)

    Loftin, B.; Abramczyk, G.; Trapp, D.

    2011-01-01

    Recently the Packaging Technology and Pressurized Systems (PT and PS) organization at the Savannah River National Laboratory was asked to develop an adapter for performing the leak-rate test of a Chalfant-style containment vessel. The PT and PS organization collaborated with designers at the Department of Energy's Pantex Plant to develop the adapter currently in use for performing the leak-rate testing on the containment vessels. This paper will give the history of leak-rate testing of the Chalfant-style containment vessels, discuss the design concept for the adapter, give an overview of the design, and will present results of the testing done using the adapter.

  3. Does the type of pancreaticojejunostomy after Whipple alter the leak rate?

    Science.gov (United States)

    Ball, Chad G; Howard, Thomas J

    2010-01-01

    Despite the overwhelming limitations that plague the literature surrounding the optimal method of reestablishing pancreatico-enteric continuity following a Whipple operation, it is clear that all successful techniques conform to sound surgical principles. These principles include a water-tight and tension-free anastomosis, preservation of adequate blood supply for both organs involved in the anastomosis, and minimal trauma to the pancreas gland. Although surgeon experience, gland texture, and pancreatic duct size are clearly the dominate risk factors from a long list of variables associated with pancreatic leaks following pancreatoduodenectomy, these are nonmodifiable covariates. Although the plethora of current literature cannot provide a single definitive technical solution for restoring pancreatico-enteric continuity, a small number of well-designed RCTs support the use of transanastomotic external stenting for high-risk pancreatic glands and an end-to-side invaginated pancreaticojejunostomy. The truth remains that an individual surgeon's mastery of a specific anastomotic technique, in conjunction with a large personal experience, is likely to be the best predictor of a low pancreas leak rate following pancreatoduodenectomy.

  4. 105-KE Basin isolation barrier leak rate test analytical development. Revision 1

    International Nuclear Information System (INIS)

    Irwin, J.J.

    1995-01-01

    This document provides an analytical development in support of the proposed leak rate test of the 105-KE Basin. The analytical basis upon which the K-basin leak test results will be used to determine the basin leakage rates is developed in this report. The leakage of the K-Basin isolation barriers under postulated accident conditions will be determined from the test results. There are two fundamental flow regimes that may exist in the postulated K-Basin leakage: viscous laminar and turbulent flow. An analytical development is presented for each flow regime. The basic geometry and nomenclature of the postulated leak paths are denoted

  5. Integrated leak rate test of the FFTF [Fast Flux Test Facility] containment vessel

    International Nuclear Information System (INIS)

    Grygiel, M.L.; Davis, R.H.; Polzin, D.L.; Yule, W.D.

    1987-04-01

    The third integrated leak rate test (ILRT) performed at the Fast Flux Test Facility (FFTF) demonstrated that effective leak rate measurements could be obtained at a pressure of 2 psig. In addition, innovative data reduction methods demonstrated the ability to accurately account for diurnal variations in containment pressure and temperature. Further development of methods used in this test indicate significant savings in the time and effort required to perform an ILRT on Liquid Metal Reactor Systems with consequent reduction in test costs

  6. Mobile natural gas leak surveys indicate that two utilities have high false negative rates

    Science.gov (United States)

    von Fischer, J. C.; Brewer, P. E.; Chamberlain, S.; Gaylord, A.; von Fischer, J.

    2016-12-01

    In the distribution systems that carry natural gas to consumers, leaks need to be discovered for safety reasons and to reduce greenhouse gas emissions. However, few utilities have adopted newer laser-based technologies that have greater sensitivity and precision, and instead rely on "industry standard" equipment that is far less sensitive. In partnership with the Environmental Defense Fund and Google, we mapped natural gas leaks in the domains of two anonymous utilities (Utility "A" and "B") using high sensitivity Picarro methane analyzers in Google Street View Cars. Surprisingly, when we shared these results with utilities, their survey crews were unable to find most of the leaks that our survey indicated (84% in A and 80% in B). To investigate this phenomenon, our team visited a subset of the leaks in each utility domain (n=32 in A and n=30 in B), and worked alongside utility surveyors to search the leak indication area, using a Los Gatos Research ultraportable methane analyzer to pinpoint leak locations. We found evidence of natural gas leaks at 69% and 68% of the locations in Utilities A and B respectively where survey crews had found nothing. We describe this as a "false negative" rate for the utility because the utility survey falsely indicated that there was no leak at these locations. Of these false negatives, 7% (n=2 of 32 in A, n=2 of 30 in B) were determined to be Grade 1 leaks requiring immediate repair due to high safety risk. Instrument sensitivity appears to explain some of the false negative rates. In particular, use of some industry standard equipment appears to have created a false sense of confidence among utility surveyors that leaks were not present. However, there was also evidence of communication failures and that surveyors did not use optimal approaches in their search. Based on these findings, we suggest that: 1) mobile deployment of high-precision methane analyzers can help find more natural gas leaks, and 2) use of some hand-held survey

  7. An Experimental Investigation of Leak Rate Performance of a Subscale Candidate Elastomer Docking Space Seal

    Science.gov (United States)

    Garafolo, Nicholas G.; Daniels, Christopher C.

    2011-01-01

    A novel docking seal was developed for the main interface seal of NASA s Low Impact Docking System (LIDS). This interface seal was designed to maintain acceptable leak rates while being exposed to the harsh environmental conditions of outer space. In this experimental evaluation, a candidate docking seal assembly called Engineering Development Unit (EDU58) was characterized and evaluated against the Constellation Project leak rate requirement. The EDU58 candidate seal assembly was manufactured from silicone elastomer S0383-70 vacuum molded in a metal retainer ring. Four seal designs were considered with unique characteristic heights. The leak rate performance was characterized through a mass point leak rate method by monitoring gas properties within an internal control volume. The leakage performance of the seals were described herein at representative docking temperatures of -50, +23, and +50 C for all four seal designs. Leak performance was also characterized at 100, 74, and 48 percent of full closure. For all conditions considered, the candidate seal assemblies met the Constellation Project leak rate requirement.

  8. Influence of chemistry on steam generator primary-to-secondary stabilized low leak flow rate

    International Nuclear Information System (INIS)

    Hervouet, C.; Pages, D.; Fauchon, C.; Bretelle, J.L.; Bus, F.

    2002-01-01

    The comparison of the leak flow rate behavior between the previous and the new boron/lithium coordination, the second one corresponding to an higher pH during the cycle than the first one, leads to the following conclusions, confirmed by the experimental and theoretical studies: Low leak flow rate is extremely sensitive to pH in the zone of pH of primary water because the behavior of metallic oxide is changing drastically in that range of pH (from precipitation to dissolution); Leak flow rate is often maintained lower with low pH. Let's recall however that pH can not reach a too low value which could enhance corrosion product deposition, increase dose rates along the primary circuit, and lead to reactor outages due to problems on fuel assemblies. The understanding of the governing phenomena led to adapt in 2000 the reactor cooling system chemical conditioning for the French Pressurized Water reactors facing problems with the management of the stabilized leak flow rate fluctuations, once no degradation of tube bundle integrity is proved. Each part of the cycle and operating conditions lead to an advised operating action. In general, the new recommendations for the reactors facing problems with the management of low leak flow rate are based on the principle of helping the precipitation of metallic oxide within the crack and preventing their dissolution. (authors)

  9. Assessment of crack opening area for leak rates

    Energy Technology Data Exchange (ETDEWEB)

    Sharples, J.K.; Bouchard, P.J.

    1997-04-01

    This paper outlines the background to recommended crack opening area solutions given in a proposed revision to leak before break guidance for the R6 procedure. Comparisons with experimental and analytical results are given for some selected cases of circumferential cracks in cylinders. It is shown that elastic models can provide satisfactory estimations of crack opening displacement (and area) but they become increasingly conservative for values of L{sub r} greater than approximately 0.4. The Dugdale small scale yielding model gives conservative estimates of crack opening displacement with increasing enhancement for L{sub r} values greater than 0.4. Further validation of the elastic-plastic reference stress method for up to L{sub r} values of about 1.0 is presented by experimental and analytical comparisons. Although a more detailed method, its application gives a best estimate of crack opening displacement which may be substantially greater than small scale plasticity models. It is also shown that the local boundary conditions in pipework need to be carefully considered when evaluating crack opening area for through-wall bending stresses resulting from welding residual stresses or geometry discontinuities.

  10. Assessment of crack opening area for leak rates

    International Nuclear Information System (INIS)

    Sharples, J.K.; Bouchard, P.J.

    1997-01-01

    This paper outlines the background to recommended crack opening area solutions given in a proposed revision to leak before break guidance for the R6 procedure. Comparisons with experimental and analytical results are given for some selected cases of circumferential cracks in cylinders. It is shown that elastic models can provide satisfactory estimations of crack opening displacement (and area) but they become increasingly conservative for values of L r greater than approximately 0.4. The Dugdale small scale yielding model gives conservative estimates of crack opening displacement with increasing enhancement for L r values greater than 0.4. Further validation of the elastic-plastic reference stress method for up to L r values of about 1.0 is presented by experimental and analytical comparisons. Although a more detailed method, its application gives a best estimate of crack opening displacement which may be substantially greater than small scale plasticity models. It is also shown that the local boundary conditions in pipework need to be carefully considered when evaluating crack opening area for through-wall bending stresses resulting from welding residual stresses or geometry discontinuities

  11. Enhancement of leak rate estimation model for corroded cracked thin tubes

    International Nuclear Information System (INIS)

    Chang, Y.S.; Jeong, J.U.; Kim, Y.J.; Hwang, S.S.; Kim, H.P.

    2010-01-01

    During the last couple of decades, lots of researches on structural integrity assessment and leak rate estimation have been carried out to prevent unanticipated catastrophic failures of pressure retaining nuclear components. However, from the standpoint of leakage integrity, there are still some arguments for predicting the leak rate of cracked components due primarily to uncertainties attached to various parameters in flow models. The purpose of present work is to suggest a leak rate estimation method for thin tubes with artificial cracks. In this context, 23 leak rate tests are carried out for laboratory generated stress corrosion cracked tube specimens subjected to internal pressure. Engineering equations to calculate crack opening displacements are developed from detailed three-dimensional elastic-plastic finite element analyses and then a simplified practical model is proposed based on the equations as well as test data. Verification of the proposed method is done through comparing leak rates and it will enable more reliable design and/or operation of thin tubes.

  12. Leak Rate Quantification Method for Gas Pressure Seals with Controlled Pressure Differential

    Science.gov (United States)

    Daniels, Christopher C.; Braun, Minel J.; Oravec, Heather A.; Mather, Janice L.; Taylor, Shawn C.

    2015-01-01

    An enhancement to the pressure decay leak rate method with mass point analysis solved deficiencies in the standard method. By adding a control system, a constant gas pressure differential across the test article was maintained. As a result, the desired pressure condition was met at the onset of the test, and the mass leak rate and measurement uncertainty were computed in real-time. The data acquisition and control system were programmed to automatically stop when specified criteria were met. Typically, the test was stopped when a specified level of measurement uncertainty was attained. Using silicone O-ring test articles, the new method was compared with the standard method that permitted the downstream pressure to be non-constant atmospheric pressure. The two methods recorded comparable leak rates, but the new method recorded leak rates with significantly lower measurement uncertainty, statistical variance, and test duration. Utilizing this new method in leak rate quantification, projects will reduce cost and schedule, improve test results, and ease interpretation between data sets.

  13. Pre-service proof pressure and leak rate tests for the Qinshan CANDU project reactor buildings

    International Nuclear Information System (INIS)

    Petrunik, K.J.; Khan, A.; Ricciuti, R.; Ivanov, A.; Chen, S.

    2003-01-01

    The Qinshan CANDU Project Reactor Buildings (Units 1 and 2) have been successfully tested for the Pre-Service Proof Pressure and Integrated Leak Rate Tests. The Unit 1 tests took place from May 3 to May 9, 2002 and from May 22 to May 25, 2002, and the Unit 2 tests took place from January 21 to January 27, 2003. This paper discusses the significant steps taken at minimum cost on the Qinshan CANDU Project, which has resulted in a) very good leak rate (0.21%) for Unit 1 and excellent leak rate (0.130%) for Unit 2; b) continuous monitoring of the structural behaviour during the Proof Pressure Test, thus eliminating any repeat of the structural test due to lack of data; and c) significant schedule reduction achieved for these tests in Unit 2. (author)

  14. The principle and data analysis of online monitoring system of containment leak rate

    International Nuclear Information System (INIS)

    Zhang Chunwei; Yang Yongdeng; Qiao Yu; Liang Bo

    2014-01-01

    The use of online monitoring system of containment leak rate (EPP) in Qinshan 2nd nuclear power plant is introduced. When the containment leak rate reaches the operational limit, the system will automatically alarm and inform the unit operator to take the necessary action. But it is found that the EPP will give a mendacious alarm of 'Containment leak rate abnormity' once in a while during use. The mendacious alarm has an effect on the normal operation of the unit. The reason of the mendacious alarm is analyzed. The data monitored by the EPP are relative hysteretic and the veracity of the flow of compressed air into the containment has a significant influence on the data monitored by the EPP. (authors)

  15. Estimation of Leak Flow Rate during Post-LOCA Using Cascaded Fuzzy Neural Networks

    Energy Technology Data Exchange (ETDEWEB)

    Kim, Dong Yeong [Korea Atomic Energy Research Institute, Daejeon (Korea, Republic of); Na, Man Gyun [Chosun University, Gwangju (Korea, Republic of)

    2016-10-15

    In this study, important parameters such as the break position, size, and leak flow rate of loss of coolant accidents (LOCAs), provide operators with essential information for recovering the cooling capability of the nuclear reactor core, for preventing the reactor core from melting down, and for managing severe accidents effectively. Leak flow rate should consist of break size, differential pressure, temperature, and so on (where differential pressure means difference between internal and external reactor vessel pressure). The leak flow rate is strongly dependent on the break size and the differential pressure, but the break size is not measured and the integrity of pressure sensors is not assured in severe circumstances. In this paper, a cascaded fuzzy neural network (CFNN) model is appropriately proposed to estimate the leak flow rate out of break, which has a direct impact on the important times (time approaching the core exit temperature that exceeds 1200 .deg. F, core uncover time, reactor vessel failure time, etc.). The CFNN is a data-based model, it requires data to develop and verify itself. Because few actual severe accident data exist, it is essential to obtain the data required in the proposed model using numerical simulations. In this study, a CFNN model was developed to predict the leak flow rate before proceeding to severe LOCAs. The simulations showed that the developed CFNN model accurately predicted the leak flow rate with less error than 0.5%. The CFNN model is much better than FNN model under the same conditions, such as the same fuzzy rules. At the result of comparison, the RMS errors of the CFNN model were reduced by approximately 82 ~ 97% of those of the FNN model.

  16. Mass Spectrometric Calibration of Controlled Fluoroform Leak Rate Devices Technique and Uncertainty Analysis

    CERN Document Server

    Balsley, S D; Laduca, C A

    2003-01-01

    Controlled leak rate devices of fluoroform on the order of 10 sup - sup 8 atm centre dot cc sec sup - sup 1 at 25 C are used to calibrate QC-1 War Reserve neutron tube exhaust stations for leak detection sensitivity. Close-out calibration of these tritium-contaminated devices is provided by the Gas Dynamics and Mass Spectrometry Laboratory, Organization 14406, which is a tritium analytical facility. The mass spectrometric technique used for the measurement is discussed, as is the first principals calculation (pressure, volume, temperature and time). The uncertainty of the measurement is largely driven by contributing factors in the determination of P, V and T. The expanded uncertainty of the leak rate measurement is shown to be 4.42%, with a coverage factor of 3 (k=3).

  17. Detecting subsurface fluid leaks in real-time using injection and production rates

    Science.gov (United States)

    Singh, Harpreet; Huerta, Nicolas J.

    2017-12-01

    CO2 injection into geologic formations for either enhanced oil recovery or carbon storage introduces a risk for undesired fluid leakage into overlying groundwater or to the surface. Despite decades of subsurface CO2 production and injection, the technologies and methods for detecting CO2 leaks are still costly and prone to large uncertainties. This is especially true for pressure-based monitoring methods, which require the use of simplified geological and reservoir flow models to simulate the pressure behavior as well as background noise affecting pressure measurements. In this study, we propose a method to detect the time and volume of fluid leakage based on real-time measurements of well injection and production rates. The approach utilizes analogies between fluid flow and capacitance-resistance modeling. Unlike other leak detection methods (e.g. pressure-based), the proposed method does not require geological and reservoir flow models to simulate the behavior that often carry significant sources of uncertainty; therefore, with our approach the leak can be detected with greater certainty. The method can be applied to detect when a leak begins by tracking a departure in fluid production rate from the expected pattern. The method has been tuned to detect the effect of boundary conditions and fluid compressibility on leakage. To highlight the utility of this approach we use our method to detect leaks for two scenarios. The first scenario simulates a fluid leak from the storage formation into an above-zone monitoring interval. The second scenario simulates intra-reservoir migration between two compartments. We illustrate this method to detect fluid leakage in three different reservoirs with varying levels of geological and structural complexity. The proposed leakage detection method has three novelties: i) requires only readily-available data (injection and production rates), ii) accounts for fluid compressibility and boundary effects, and iii) in addition to

  18. K West basin isolation barrier leak rate test

    International Nuclear Information System (INIS)

    Whitehurst, R.; McCracken, K.; Papenfuss, J.N.

    1994-01-01

    This document establishes the procedure for performing the acceptance test on the two isolation barriers being installed in K West basin. This acceptance test procedure shall be used to: First establish a basin water loss rate prior to installation of the two isolation barriers between the main basin and the discharge chute in K-Basin West. Second, perform an acceptance test to verify an acceptable leakage rate through the barrier seals

  19. Influence of wetting effect at the outer surface of the pipe on increase in leak rate - experimental results and discussion

    Energy Technology Data Exchange (ETDEWEB)

    Isozaki, Toshikuni; Shibata, Katsuyuki

    1997-04-01

    Experimental and computed results applicable to Leak Before Break analysis are presented. The specific area of investigation is the effect of the temperature distribution changes due to wetting of the test pipe near the crack on the increase in the crack opening area and leak rate. Two 12-inch straight pipes subjected to both internal pressure and thermal load, but not to bending load, are modelled. The leak rate was found to be very susceptible to the metal temperature of the piping. In leak rate tests, therefore, it is recommended that temperature distribution be measured precisely for a wide area.

  20. RCSLK9: reactor coolant system leak rate determination for PWRs. User's guide

    International Nuclear Information System (INIS)

    Kirkpatrick, D.C.; Woodruff, R.W.; Holland, R.A.

    1984-12-01

    RCSLK9 is a computer program that was developed to analyze the leak tightness of the primary cooling system for any pressurized water reactor. From system conditions, water levels in tanks, and certain system design parameters, RCSLK9 calculates the loss of water from the cooling system and the increase of water in the leakage collection system during an arbitrary time interval. The program determines the system leak rates and displays or prints a report of the results. For initial application of the program at a reactor, RCSLK9 creates a file of system parameters and stores it for future use. RCSLK9 is written for use on the IBM PC

  1. The PWR integrated leak rate test, a review of experiences and results

    International Nuclear Information System (INIS)

    Keogh, P.

    1985-01-01

    The paper reviews the Integrated Leak Rate Test (ILRT) as it has been carried out in the USA and as reported in papers in European countries. The test procedures are critically appraised and recommendations are given for modifications to them. The values used in a PWR are identified as a main source of leaks and possibilities for improvement are discussed. The use of a part pressure test and its limitations are considered. A part pressure test cannot give the same assurance as a full pressure test but may be useful for the identification of gross leaks. Secondary effects such as weather and the use of Van de Waals equations are considered and are found to be not important for concrete containments. (orig.)

  2. Leak Rate Performance of Silicone Elastomer O-Rings Contaminated with JSC-1A Lunar Regolith Simulant

    Science.gov (United States)

    Oravec, Heather Ann; Daniels, Christopher C.

    2014-01-01

    Contamination of spacecraft components with planetary and foreign object debris is a growing concern. Face seals separating the spacecraft cabin from the debris filled environment are particularly susceptible; if the seal becomes contaminated there is potential for decreased performance, mission failure, or catastrophe. In this study, silicone elastomer O-rings were contaminated with JSC- 1A lunar regolith and their leak rate performance was evaluated. The leak rate values of contaminated O-rings at four levels of seal compression were compared to those of as-received, uncontaminated, O-rings. The results showed a drastic increase in leak rate after contamination. JSC-1A contaminated O-rings lead to immeasurably high leak rate values for all levels of compression except complete closure. Additionally, a mechanical method of simulant removal was examined. In general, this method returned the leak rate to as-received values.

  3. Hermetic Seal Leak Detection Apparatus

    Science.gov (United States)

    Kelley, Anthony R. (Inventor)

    2013-01-01

    The present invention is a hermetic seal leak detection apparatus, which can be used to test for hermetic seal leaks in instruments and containers. A vacuum tight chamber is created around the unit being tested to minimize gas space outside of the hermetic seal. A vacuum inducing device is then used to increase the gas chamber volume inside the device, so that a slight vacuum is pulled on the unit being tested. The pressure in the unit being tested will stabilize. If the stabilized pressure reads close to a known good seal calibration, there is not a leak in the seal. If the stabilized pressure reads closer to a known bad seal calibration value, there is a leak in the seal. The speed of the plunger can be varied and by evaluating the resulting pressure change rates and final values, the leak rate/size can be accurately calculated.

  4. Essential results of analyses accompanying the leak rate experiments E22 at HDR

    International Nuclear Information System (INIS)

    Grebner, H.; Hoefler, A.; Hunger, H.

    1994-01-01

    Under the E22 test group of phase III of the HDR safety programme, experiments were performed on the crack opening and leak rate behaviour of pipe components of smaller nominal bores. The experiments were complemented by computations, in particular verifications, to qualify the computation models as one of the main aims of the HDR safety programme. Most of the analyses to determine crack openings were performed by means of the finite-element method, including elastic-plastic materials behaviour and, complementarily, assessing engineering methods. The leak rate was calculated by means of separate 2-phase computation models. Altogether, it may be concluded from the structural and fracture mechanical experiments with pipes, elbows and branch pieces, that crack openings and incipient cracks at loading with internal pressure or bending moment can be described with good accuracy by means of the finite-element programme ADINA and the developed FE-models. (orig.) [de

  5. VAMCIS, a new measuring channel for continuous monitoring of leak rates inside PWR steam generators

    International Nuclear Information System (INIS)

    Champion, G.; Dubail, A.; Lefevre, F.

    1988-01-01

    In order to assess the primary to secondary leakage, radioactive isotopes, formed in the primary coolant as a result of fission or neutron capture, are usually monitored in the pressurized water reactor (PWR) secondary coolant. Conventional methods mainly based on the detection of 133 Xe, tritium, and 41 Ar are widely used on French Electricite de France (EdF) PWRs. Some years ago, it appeared necessary to improve both leak rate assessments and steam generator tube rupture (SGTR) detection. A volumetric activity measuring channel inside steam (VAMCIS) has been developed for this purpose. The SGTR that occurred at the North Anna PWR has focused the attention of safety authorities on this new measuring channel. It is planned to implement VAMCIS at North Anna in order to check the leak rate variations more accurately

  6. Pre- and post-calculations for crack opening and leak rate experiments on piping components within the HDR-program

    International Nuclear Information System (INIS)

    Grebner, H.; Hoefler, A.; Hunger, H.

    1991-01-01

    In this paper calculations to experiments on leak opening and leak rates of piping components are presented. The experiments are performed at the HDR-facility at Karlstein/Germany and up to now straight pipes and pipe branches were considered. Numerical and experimental results are compared. (author)

  7. Determination of crack morphology parameters from service failures for leak-rate analyses

    Energy Technology Data Exchange (ETDEWEB)

    Wilkowski, G.; Ghadiali, N.; Paul, D. [Battelle Memorial Institute, Columbus, OH (United States)] [and others

    1997-04-01

    In leak-rate analyses described in the literature, the crack morphology parameters are typically not well agreed upon by different investigators. This paper presents results on a review of crack morphology parameters determined from examination of service induced cracks. Service induced cracks were found to have a much more tortuous flow path than laboratory induced cracks due to crack branching associated with the service induced cracks. Several new parameters such as local and global surface roughnesses, as well as local and global number of turns were identified. The effect of each of these parameters are dependent on the crack-opening displacement. Additionally, the crack path is typically assumed to be straight through the pipe thickness, but the service data show that the flow path can be longer due to the crack following a fusion line, and/or the number of turns, where the number of turns in the past were included as a pressure drop term due to the turns, but not the longer flow path length. These parameters were statistically evaluated for fatigue cracks in air, corrosion-fatigue, IGSCC, and thermal fatigue cracks. A refined version of the SQUIRT leak-rate code was developed to account for these variables. Sample calculations are provided in this paper that show how the crack size can vary for a given leak rate and the statistical variation of the crack morphology parameters.

  8. Low anastomotic leak rate after colorectal surgery: a single-centre study.

    Science.gov (United States)

    Jones, O M; John, S K P; Horseman, N; Lawrance, R J; Fozard, J B J

    2007-10-01

    Anastomotic leak after colorectal surgery is a serious event associated with significant morbidity and mortality. There is little consensus regarding 'acceptable' rates of leakage, however. This study describes the experience of anastomotic leakage after both elective and emergency colorectal surgery in a district general hospital. A prospectively collected database of all patients with a diagnosis of colorectal cancer in a single hospital formed the basis of the study. Leak was defined as breakdown of the anastomosis contributing to death or requiring reoperation or reintervention. A total of 949 patients underwent surgery with an anastomosis between 1996 and 2004, including 331 patients treated with anterior resection. Anastomotic leaks requiring reoperation occurred in eight patients (0.8%). Thirty-day and in-hospital mortality was 4%. A very low rate of anastomotic leakage after colorectal surgery is possible in a district general hospital setting. Given the impact of anastomotic leakage on function, tumour recurrence and long-term survival, it should be considered as a marker of surgical quality when evaluating surgical performance.

  9. Assessments of fluid friction factors for use in leak rate calculations

    Energy Technology Data Exchange (ETDEWEB)

    Chivers, T.C. [Berkeley Technology Centre, Glos (United Kingdom)

    1997-04-01

    Leak before Break procedures require estimates of leakage, and these in turn need fluid friction to be assessed. In this paper available data on flow rates through idealized and real crack geometries are reviewed in terms of a single friction factor k It is shown that for {lambda} < 1 flow rates can be bounded using correlations in terms of surface R{sub a} values. For {lambda} > 1 the database is less precise, but {lambda} {approx} 4 is an upper bound, hence in this region flow calculations can be assessed using 1 < {lambda} < 4.

  10. Essential results of analyses accompanying the leak rate experiments E22 at HDR

    International Nuclear Information System (INIS)

    Grebner, H.; Hoefler, A.; Hunger, H.

    1997-01-01

    During phase III of the HDR Safety Programme (HDR: decommissioned overheated steam reactor in Karlstein, Germany), experiments were performed in test group E22 on small-bore austenitic straight piping and on pipe elbows and branches containing through-wall cracks. The main aim was the determination of crack opening and leak rate behaviour for the cracked components under almost operational pressure and temperature loading conditions, especially including transient bending moments. In addition to machined slits, naturally grown fatigue cracks were also considered to cover the leakage behaviour. The experiments were accompanied by calculations, mainly performed by GRS. The paper describes the most important aspects and the essential results of the calculations and analysis. The main outcome was that the crack opening and initiation of crack growth can be described with the finite element techniques applied with sufficient accuracy. However, the qualification of the leak rate models could not be completed successfully, and therefore more sophisticated experiments of this kind are needed. (orig.)

  11. Results of a bench mark test on the crack opening and leak rate calculation

    International Nuclear Information System (INIS)

    Grebner, H.

    1995-01-01

    Results of a bench mark test on the standard problem calculation of crack opening and leak rate in piping components are presented. The bench mark test is based on two experiments performed in phase III of the German HDR safety program. The pipe sections considered in these experiments were a straight pipe with an 80 mm diameter containing a circumferential wall penetrating crack and a pipe branch DN 100/DN 25 with a crack in the weldment between the nozzle and the main pipe. Both test pieces were made of austenitic steel and were loaded by internal pressure and bending moment. For the evaluation of the crack opening either analytical methods or estimation schemes or the finite element method were used, while leak rates were calculated by means of two-phase flow methods. The compilation of the results shows very large scatter bands in general, with deviations between calculated and measured values of up to some one hundred percent. Reasons for this behaviour are uncertainties in the measured data and their evaluation as well as the different methods of calculation and their uncertainties. (author)

  12. Integrated leak rate testing of the fast flux test facility reactor containment building

    International Nuclear Information System (INIS)

    James, E.B.; Farabee, O.A.; Bliss, R.J.

    1978-01-01

    The initial Integrated Leak Rate Test (ILRT) of the Fast Flux Test Facility containment building was performed from May 27 to June 2, 1978. The test was conducted in air with systems vented and with the containment recirculating coolers in operation. 10 psig and 5 psig tests were run using the absolute pressure test method. The measured leakage rates were .033% Vol/24 hr. and -.0015% Vol/24 hrs. respectively. Subsequent verification tests at both 10 psig and 5 psig proved that the test equipment was operating properly and it was sensitive enough to detect leaks at low pressures. This ILRT was performed at a lower pressure than any previous ILRT on a reactor containment structure in the United States. While the initial design requirements for ice condenser containments called for a part pressure test at 6 psig, the tests were waived due to the apparent statistical problems of data analysis and the repeatability of the data itself at such low pressure. In contrast to this belief, both the 5 and 10 psig ILRT's were performed in a successful manner at FFTF

  13. Study of air and steam leak rate through damaged concrete wall

    International Nuclear Information System (INIS)

    Abdeslam Laghcha; Gerard Debicki; Benoit Masson

    2005-01-01

    Full text of publication follows: The leak rate prediction of air and steam through a cracked concrete wall is an extremely important issue in assessing the safety of nuclear reactor containment building. Furthermore the relation between air leak rate and steam leak rate on the same wall could have some interest for safety prediction. This laboratory study investigates the transfer of fluids through a wall of 1.3 m of thickness, with a focus on two cases: one on a mechanically damaged concrete by compressive stress and another one on a crossing artificial flaw in a construction joint realized in the concrete specimen (cylindrical / section 0.1925 m 2 / length 1.3 m). The both specimens were made of ordinary concrete (compressive strength: 35 MPa). To initiate residual compressive cracks, the specimen (A) was loaded in compression under controlled strains until a level of 90% of the failure strain was reached. To create a crossing artificial flaw in a construction joint, the concrete was set in the mould in two times, the second time, a water saturated sand bed was placed on the surface of the hardened concrete to realize the flaw along a diameter of the specimen (B). The permeability of damaged concrete wall was studied comparatively under two conditions, but without appreciable stresses applied on. The first condition was at ambient temperature, a reference test of permeability, with dry air, gave the characteristics of permeability and the type of flow through the specimen. In this case, the used method consisted to proceed by stages. The imposed pressures on the exposed face were successively 0.1, 0.18, 0.23, 0.28, 0.34 and 0.42 MPa, the other face was at atmospheric pressure. The second condition was an accidental scenario with simultaneous effects of temperature and gas (a mix of air and steam) pressure applied on a face, the other one remaining at atmospheric pressure and temperature. During the test, the lateral face of the cylindrical specimen was thermally

  14. Livaditis' circular myotomy does not decrease anastomotic leak rates and induces deleterious changes in anastomotic healing.

    Science.gov (United States)

    Tannuri, U; Teodoro, W R; de Santana Witzel, S; Tannuri, A C A; Lupinacci, R M; Matsunaga, P; Matsumura, N; Naufal, R R

    2003-08-01

    Considering that Livaditis' myotomy is still accepted as a good method for lengthening the esophagus to allow primary repair of long-gap esophageal atresia, the aim of this experimental study was to verify if this procedure decreases the incidence of leaks in anastomoses performed under severe tension. In addition, it was verified whether the myotomy promotes any morphological or biochemical change in the healing esophageal anastomosis. Sixty small dogs were submitted to a cervicotomy and resection of an esophageal segment (8.0 - 10.0 cm) resulting in an anastomosis under severe tension. The animals were divided into two groups (control group: only anastomosis; experimental group: anastomosis plus circular myotomy in the proximal esophageal segment). The animals were sacrificed on the 14th postoperative day, submitted to autopsy, and were evaluated as to the presence of leaks. Twelve scars of each group were collected for histological, histomorphometric (evaluation of scar thickness), electrophoretic and immunoblotting studies of collagen (total collagen and types of collagen determinations). Leak rates were the same in both groups. Histologic examination showed that the scar at the anastomosis was formed by fibrous tissue, without mucosa or muscular tissue. In the myotomy animals, a decreased number of newly formed small vessels was noted in comparison to control animals, and morphometric analysis showed that in the myotomy animals the anastomotic scar was thinner than in the control animals. Biochemical analysis of scars demonstrated that myotomy promoted a decrease in the soluble collagen content in comparison with the control animals and no alteration in the content of insoluble collagen. The electrophoretic separation of the types of collagen and characterization by immunoblotting demonstrated the presence of collagen types I, III, and V, and the quantification by densitometry of the bands showed a reduction in collagen type V (present in the blood vessels) in

  15. The influence of data collection rate, containment size and data smoothing on containment Integrated Leak Rate Tests

    International Nuclear Information System (INIS)

    Wagner, W.T.; Langan, J.P.; Norris, W.E.; Lurie, D.

    1988-01-01

    Phase I of a U.S. Nuclear Regulatory Commission contract investigated nuclear power plant Integrated Leak Rate Tests (ILRTs) using data gathered at many domestic and foreign ILRTs. The study evaluated ILRTs with the ANS criteria (in ANSI/ANS-56.8-1987) and the proposed extended ANS criteria (in draft Regulatory Guide, Task MS 021-5, October 1986). The study considered (1) the effects of data collection rates on ILRT conclusions, (2) a possible relationship between containment size, data collection rate and ILRT duration, (3) the impact of the proposed extended ANS methodology on ILRTs, and (4) the influence of data smoothing on ILRT data. The study was performed using 20 sets of Type A and 17 sets of verification data

  16. Evaluation of methodologies for the calculation of leak rates for pressure retaining components with crack-like leaks; Bewertung von Methoden zur Berechnung von Leckraten fuer druckfuehrende Komponenten mit rissartigen Lecks

    Energy Technology Data Exchange (ETDEWEB)

    Sievers, Juergen; Heckmann, Klaus; Blaesius, Christoph

    2015-06-15

    For the demonstration of break preclusion for pressure retaining components in nuclear power plants, the nuclear safety standard KTA 3206 determines also the requirements for the leak-before-break verification. For this procedure, it has to be ensured that a wall-penetrating crack is subcritical with respect to instable growth, and that the resulting leakage under stationary operation conditions can be detected by a leak detection system. Within the scope of the project 3613R01332 analyses with respect to conservative estimates of the leak rates in case of detections regarding break preclusion were performed by means of leak rate models being available at GRS. For this purpose, conservative assumptions in the procedure were quantified by comparative calculations concerning selected leak rate experiments and the requirements regarding the determination of leak rates indicated in the KTA 3206 were verified and specified. Moreover, the models were extended and relevant recommendations for the calculation procedure were developed. During the investigations of leak rate tests the calculation methods were validated, qualified by means of both examples indicated in KTA 3206 and applied to a postulated leak accident in the cooling circuit of a PWR. For the calculation of leak rates several simplified solution methods which are included in the GRS program WinLeck were applied, and for the simulation of a leak accident the large-scale programs ANSYS Mechanical and ATHLET (thermohydraulics program developed by GRS) were used. When applying simplified methods for the calculation of leak rates using the limiting curve for the friction factor which has been derived during the project and which is included in the KTA 3206 attention has to be paid to the fact that in case of small flow lengths the entrance loss can dominate compared to the friction loss. However, the available data do not suffice in order to make a quantitative statement with respect to limits of applicability

  17. Crack shape developments and leak rates for circumferential complex-cracked pipes

    Energy Technology Data Exchange (ETDEWEB)

    Brickstad, B.; Bergman, M. [SAQ Inspection Ltd., Stockholm (Sweden)

    1997-04-01

    A computerized procedure has been developed that predicts the growth of an initial circumferential surface crack through a pipe and further on to failure. The crack growth mechanism can either be fatigue or stress corrosion. Consideration is taken to complex crack shapes and for the through-wall cracks, crack opening areas and leak rates are also calculated. The procedure is based on a large number of three-dimensional finite element calculations of cracked pipes. The results from these calculations are stored in a database from which the PC-program, denoted LBBPIPE, reads all necessary information. In this paper, a sensitivity analysis is presented for cracked pipes subjected to both stress corrosion and vibration fatigue.

  18. Probabilistic pipe fracture evaluations for applications to leak-rate detection

    Energy Technology Data Exchange (ETDEWEB)

    Rahman, S; Wilkowski, G; Ghadiali, N [Battelle Columbus Labs., OH (United States)

    1993-12-31

    Stochastic pipe fracture evaluations are conducted for applications to leak-rate detection. A state-of-the-art review was first conducted to evaluate the adequacy of current deterministic models for thermo-hydraulic and elastic-plastic fracture analyses. Then a new probabilistic model was developed with the above deterministic models for structural reliability analysis of cracked piping systems and statistical characterization of crack morphology parameters, material properties of pipe, and crack location. The proposed models are then applied for computing conditional probability of failure for various nuclear piping systems in BWR and PWR plants. The PRAISE code was not used, and the probabilistic model is based on modern methods of stochastic mechanics, computationally far superior to Monte Carlo and Stratified Sampling methods used in PRAISE. 10 refs., 9 figs., 1 tab.

  19. Probabilistic pipe fracture evaluations for applications to leak-rate detection

    International Nuclear Information System (INIS)

    Rahman, S.; Wilkowski, G.; Ghadiali, N.

    1992-01-01

    Stochastic pipe fracture evaluations are conducted for applications to leak-rate detection. A state-of-the-art review was first conducted to evaluate the adequacy of current deterministic models for thermo-hydraulic and elastic-plastic fracture analyses. Then a new probabilistic model was developed with the above deterministic models for structural reliability analysis of cracked piping systems and statistical characterization of crack morphology parameters, material properties of pipe, and crack location. The proposed models are then applied for computing conditional probability of failure for various nuclear piping systems in BWR and PWR plants. The PRAISE code was not used, and the probabilistic model is based on modern methods of stochastic mechanics, computationally far superior to Monte Carlo and Stratified Sampling methods used in PRAISE. 10 refs., 9 figs., 1 tab

  20. Reduction of Large Dynamical Systems by Minimization of Evolution Rate

    Science.gov (United States)

    Girimaji, Sharath S.

    1999-01-01

    Reduction of a large system of equations to a lower-dimensional system of similar dynamics is investigated. For dynamical systems with disparate timescales, a criterion for determining redundant dimensions and a general reduction method based on the minimization of evolution rate are proposed.

  1. Minimizing Symbol Error Rate for Cognitive Relaying with Opportunistic Access

    KAUST Repository

    Zafar, Ammar

    2012-12-29

    In this paper, we present an optimal resource allocation scheme (ORA) for an all-participate(AP) cognitive relay network that minimizes the symbol error rate (SER). The SER is derived and different constraints are considered on the system. We consider the cases of both individual and global power constraints, individual constraints only and global constraints only. Numerical results show that the ORA scheme outperforms the schemes with direct link only and uniform power allocation (UPA) in terms of minimizing the SER for all three cases of different constraints. Numerical results also show that the individual constraints only case provides the best performance at large signal-to-noise-ratio (SNR).

  2. Summary of PWR leak detection studies

    International Nuclear Information System (INIS)

    Cho, J.H.; Elia, F.A. Jr.

    1986-01-01

    Thermal-hydraulic analysis can be used to determine the location and magnitude of leaks inside and location of leaks outside a pressurized water reactor (PWR) containment as required by plant technical specifications. The major advantage of this detection method is that it minimizes radiation exposure of maintenance personnel because most of the leak detection process is performed from the control room outside containment. Plant-specific analyses are utilized to predict change in parameters such as local dew point temperature, relative humidity, dry bulb temperature, and flow rate to sump for various leak rates and enthalpies. These parameter responses are then programmed into the plant computer and instrumentation is provided for area monitoring. The actual inputs are continuously monitored and compared to the predicted plant responses to identify the leak location and quantify the leak. This study concludes that a system that monitors dew point (or relative humidity) and dry bulb temperature changes together with the flow rate to the sump will provide the capability to both locate and quantify a leak inside a containment, while a system that monitors dew point temperature (or relative humidity) changes will provide the capability to locate a leak outside a containment

  3. Measured Leak Rate of Ammonia Through an Epoxy/Stainless-Steel Patch

    National Research Council Canada - National Science Library

    Brady, B. B; Desain, J. D; Curtiss, T. J

    2007-01-01

    .... To assess the lifetime of the patch and sensitivity to manufacturing variation, simulated leaks in circular aluminum discs were patched with several different variants on the same epoxy-stainless materials system...

  4. A Comparative Risk Assessment of Extended Integrated Leak Rate Testing Intervals

    Energy Technology Data Exchange (ETDEWEB)

    Oh, Ji Yong; Hwang, Seok Won; Lee, Byung Sik [Korea Hydro and Nuclear Power Co., Daejeon (Korea, Republic of)

    2009-10-15

    This paper presents the risk impacts of extending the Integrated Leak Rate Testing (ILRT) intervals (from five years to ten years) of Yonggwang (YGN) Unit 1 and 2. These risk impacts depended on the annual variances of meteorological data and resident population. Main comparisons were performed between the initial risk assessment (2005) for the purpose of extending ILRT interval and risk reassessment (2009) where the changed plant internal configurations (core inventory and radioisotope release fraction) and plant external alterations (wind directions, rainfall and population distributions) were monitored. The reassessment showed that there was imperceptible risk increase when the ILRT interval was extended compared to the initial risk assessment. In addition, the increased value of the Large Early Release Frequency (LERF) also satisfied the acceptance guideline proposed on Reg. Guide 1.174. The MACCS II code was used for evaluating the offsite consequence analysis. The primary risk index were used as the Probabilistic Population Dose (PPD) by considering the early effects within 80 km. The Probabilistic Safety Assessment (PSA) of YGN 1 and 2 was applied to evaluate the accident frequency of each source term category and the used PSA scope was limited to internal event.

  5. Study on DOP substitutes for leaking rate testing of HEPA filter used in nuclear air cleaning systems

    International Nuclear Information System (INIS)

    Qiu Dangui; Zhang Jirong; Hou Jianrong; Qiao Taifei; Shen Dapeng; Shi Yingxia

    2012-01-01

    Based on an extensive investigation over available literatures concerning HEPA filter testing, PEG400, SHELL on dina oil 15 and P.a. were chosen as candidates for Dop substitutes, and on which a series of tests were conducted about their aerosol conversion rate, particle size distribution, Dop detector response and leaking rate in H EPA filter. With consideration of technical properties, safety performance and economy, homemade P.a. is finally selected as the best substitute for Dop among the three. (authors)

  6. Determining Methane Leak Locations and Rates with a Wireless Network Composed of Low-Cost, Printed Sensors

    Science.gov (United States)

    Smith, C. J.; Kim, B.; Zhang, Y.; Ng, T. N.; Beck, V.; Ganguli, A.; Saha, B.; Daniel, G.; Lee, J.; Whiting, G.; Meyyappan, M.; Schwartz, D. E.

    2015-12-01

    We will present our progress on the development of a wireless sensor network that will determine the source and rate of detected methane leaks. The targeted leak detection threshold is 2 g/min with a rate estimation error of 20% and localization error of 1 m within an outdoor area of 100 m2. The network itself is composed of low-cost, high-performance sensor nodes based on printed nanomaterials with expected sensitivity below 1 ppmv methane. High sensitivity to methane is achieved by modifying high surface-area-to-volume-ratio single-walled carbon nanotubes (SWNTs) with materials that adsorb methane molecules. Because the modified SWNTs are not perfectly selective to methane, the sensor nodes contain arrays of variously-modified SWNTs to build diversity of response towards gases with adsorption affinity. Methane selectivity is achieved through advanced pattern-matching algorithms of the array's ensemble response. The system is low power and designed to operate for a year on a single small battery. The SWNT sensing elements consume only microwatts. The largest power consumer is the wireless communication, which provides robust, real-time measurement data. Methane leak localization and rate estimation will be performed by machine-learning algorithms built with the aid of computational fluid dynamics simulations of gas plume formation. This sensor system can be broadly applied at gas wells, distribution systems, refineries, and other downstream facilities. It also can be utilized for industrial and residential safety applications, and adapted to other gases and gas combinations.

  7. Minimalism

    CERN Document Server

    Obendorf, Hartmut

    2009-01-01

    The notion of Minimalism is proposed as a theoretical tool supporting a more differentiated understanding of reduction and thus forms a standpoint that allows definition of aspects of simplicity. This book traces the development of minimalism, defines the four types of minimalism in interaction design, and looks at how to apply it.

  8. Study on the Leak Rate Estimation of SG Tubes and Residual Stress Estimation based on Plastic Deformation

    Energy Technology Data Exchange (ETDEWEB)

    Kim, Young Jin; Chang, Yoon Suk; Lee, Dock Jin; Lee, Tae Rin; Choi, Shin Beom; Jeong, Jae Uk; Yeum, Seung Won [Sungkyunkwan University, Seoul (Korea, Republic of)

    2009-02-15

    In this research project, a leak rate estimation model was developed for steam generator tubes with through wall cracks. The modelling was based on the leak data from 23 tube specimens. Also, the procedure of finite element analysis was developed for residual stress calculation of dissimilar metal weld in a bottom mounted instrumentation. The effect of geometric variables related with the residual stress in penetration weld part was investigated by using the developed analysis procedure. The key subjects dealt in this research are: 1. Development of leak rate estimation model for steam generator tubes with through wall cracks 2. Development of the program which can perform the structure and leakage integrity evaluation for steam generator tubes 3. Development of analysis procedure for bottom mounted instrumentation weld residual stress 4. Analysis on the effects of geometric variables on weld residual stress It is anticipated that the technologies developed in this study are applicable for integrity estimation of steam generator tubes and weld part in NPP.

  9. Leak detection/verification

    Energy Technology Data Exchange (ETDEWEB)

    Krhounek, V.; Zdarek, J.; Pecinka, L. [Nuclear Research Institute, Rez (Czech Republic)

    1997-04-01

    Loss of coolant accident (LOCA) experiments performed as part of a Leak Before Break (LBB) analysis are very briefly summarized. The aim of these experiments was to postulate the leak rates of the coolant. Through-wall cracks were introduced into pipes by fatigue cycling and hydraulically loaded in a test device. Measurements included coolant pressure and temperature, quantity of leaked coolant, displacement of a specimen, and acoustic emission. Small cracks were plugged with particles in the coolant during testing. It is believed that plugging will have no effect in cracks with leak rates above 35 liters per minute. The leak rate safety margin of 10 is sufficient for cracks in which the leak rate is more than 5 liters per minute.

  10. Mockup experiments to investigate the leak rate correlation between mercury and helium for the mercury target system of J-PARC

    International Nuclear Information System (INIS)

    Haga, Katsuhiro; Naoe, Takashi; Kogawa, Hiroyuki; Wakui, Takashi; Futakawa, Masatoshi

    2009-01-01

    Checking the seal performance of the mercury piping network is very important for the mercury target system operation of J-PARC, and the test method for leaks using the pressure change measurement is preferable for this purpose because it can be carried out easily and precisely by measuring the pressure change, and it is free from the risk of mercury contamination. The piping network is pressurized by helium gas. Thus, the correlation between the helium leak rate and mercury leak flow rate was investigated experimentally by carrying out leak tests for helium and mercury with an identical mockup flange model. The results showed that the mercury leak flow rates of the experimental data were lower than those of the estimated value by 64% on average. It was also found that the threshold of the helium leak rate at which good seal performance for mercury can be obtained exists between 2.18 x 10 -4 and 1.01 x 10 -2 Pa.m 3 /s. This fact confirmed the sufficient safety margin of the mercury target system against the mercury leak, where 1 x 10 -6 Pa.m 3 /s was adopted as the seal performance criterion. (author)

  11. Ultrasensitive leak detection

    International Nuclear Information System (INIS)

    Winkelman, C.R.; Davidson, H.G.

    1978-01-01

    The objective of this investigation was to develop a method of detecting leaks to a sensitivity of 1.0 x 10 -13 std/cm 3 /s in vacuum devices and to develop a qualifiable standard leak to provide system calibration at this leak rate. The development work demonstrated that minimum detectable leak rates of 6.5 x 10 -14 std/cm 3 /s and 5.5 x 10 -15 std/cm 3 /s are possible for respective analog and digital measurement modes

  12. Permanent underwater leak detector

    International Nuclear Information System (INIS)

    Costello, L; McStay, D; Moodie, D; Kane, D

    2009-01-01

    A new optoelectronic sensor for the real time monitoring of key components such as valves and connectors within the subsea production equipment for leaks of hydraulic fluid is reported. The sensor is capable of detecting low concentrations of such fluids, allowing the early detection of small leaks, and the ability to monitor the evolution of the leak-rate with time, hence providing an important new tool in complying with environmental requirements, enabling early intervention and optimising subsea production

  13. Reactor building pressure proof test (PPT) and leak rate test (LRT) of Qinshan phase III (CANDU) project

    International Nuclear Information System (INIS)

    Gu Jun; Shi Jinqi; Fan Fuping

    2004-12-01

    As the first reactor building (R/B) without stainless steel liner in china, TQNPC studied the containment characteristics, such as strong concrete absorb/release air effect, poor containment penetration. etc. And carefully prepared test scheme and emergency response, creatively introduced the instrument air self-supply system in reactor building, developed the special measurement and analysis system for PPT and LRT, organized work under high-pressure on large-scale in the test. Finally got the containment leak rate result and the test-cost-time value is the best in all same type tests. (authors)

  14. A study on a real-time leak detection method for pressurized liquid refrigerant pipeline based on pressure and flow rate

    International Nuclear Information System (INIS)

    Tian, Shen; Du, Juanli; Shao, Shuangquan; Xu, Hongbo; Tian, Changqing

    2016-01-01

    Highlights: • A real-time leak detection method is developed for ammonia pipeline in cold storage. • A locating algorithm based on pressure difference profile is provided. • This method is validated by R22 and ammonia leak experiments. • The minimum detectable leak ratio is 1% for R22 and 4% for ammonia. • The location estimating errors are −27% ~ 17% for R22 and −27% ~ 27% for ammonia. - Graphical Abstract: - Abstract: Leakage from pressurized liquid ammonia pipeline has been a serious problem in large commercial cold storages because it might release large amount of liquid ammonia and without safety supervision in daily operations. The present paper shows a detection method for a pressurized liquid ammonia pipeline with a leak. The variations of pressure, flow rate and pressure difference profile are studied. A leak indicator (σ), proposed with the one-dimensional steady-state flow model, is used to detect the leak occurrence by comparing it with a threshold value (σ Le ). A locating algorithm based on pressure difference profile along the pipeline is also proposed, which has considered the effect of the static pressure increase at the leak point. Experiments on different leak positions and ratios from liquid R22 and ammonia pipelines are carried out to validate this method. It is found that, with a relatively low false alarm rate (as three percent), the minimum detectable leak ratio reached 1% for the R22 pipeline and 4% for the ammonia pipeline. The locating errors are between −27% ~ 17% for R22 pipeline and −27% ~ 27% for ammonia pipeline.

  15. Minimizing Symbol Error Rate for Cognitive Relaying with Opportunistic Access

    KAUST Repository

    Zafar, Ammar; Alouini, Mohamed-Slim; Chen, Yunfei; Radaydeh, Redha M.

    2012-01-01

    outperforms the schemes with direct link only and uniform power allocation (UPA) in terms of minimizing the SER for all three cases of different constraints. Numerical results also show that the individual constraints only case provides the best performance at large signal-to-noise-ratio (SNR).

  16. Experiments in LEENA facility with modified wire type leak detector layout in large sodium pipelines

    International Nuclear Information System (INIS)

    Vijayakumar, G.; Chandramouli, S.; Nashine, B.K.; Selvaraj, P.; Rajan, K.K.

    2017-01-01

    Highlights: • FBR large horizontal secondary pipeline were simulated and five sodium leak experiments were conducted by providing modified wire type leak detector layout at 550 °C. • Early detection of sodium leak is needed for minimizing the sodium leaked out and consequent damages. • PFBR leak detector layout on large horizontal pipelines can detect a leak rate of 200 g/h within 6 h. • By reducing the distance between leak point and detector to half, detection time was reduced to 1/6th and found that a leak rate of 200 g/h can be detected in one hour. • A relationship between leak rate and detection time was established based on experimental results. - Abstract: Sodium cooled Fast Breeder Reactors (SFRs) are envisaged in the second phase of Indian nuclear power programme. Liquid sodium is used as the coolant in the SFRs due to its favourable nuclear properties and excellent heat transfer properties. Leaks in sodium systems have the potential of being exceptionally hazardous due to the reaction of liquid sodium with oxygen and water vapour in the air. When a sodium leak occurs, the sodium leak rate, the total quantity of sodium leaked and leak detector layout governs the detection time. Other factors to be considered are insulation material packing condition, distance between the leak point and detector, heater layout, pipe geometry, temperature etc. Potential regions of leakage in Fast Breeder Reactor (FBR) sodium circuits are near welds, high stress areas and regions subjected to thermal striping. Early detection of leak is needed for minimizing the quantity of sodium leaked to outside and consequent damages. Three wire type leak detectors (WLDs positioned at 90°, 180° and 270°) working on conductivity principle are used for detecting sodium leak in the large horizontal secondary sodium pipelines of Prototype Fast Breeder Reactor (PFBR). It was found from the upper boundary curve based on LEENA (LEak Experiments in NAtrium) facility experimental

  17. Minimal rates for lepton flavour violation from supersymmetric leptogenesis

    International Nuclear Information System (INIS)

    Ibarra, A; Simonetto, C

    2010-01-01

    The see-saw is a very attractive model for neutrino mass generation in particular in association with supersymmetry as a solution to the hierarchy problem. Under the plausible assumptions of hierarchical neutrino Yukawa eigenvalues and the absence of cancellations, we derive an upper bound on the lightest right-handed neutrino mass from the non-observation of μ → eγ and μ-e conversion in nuclei. The ongoing experiment MEG as well as the planned experiments Mu2e, COMET and PRISM/PRIME will improve this bound if no evidence of lepton flavour violation is found. We lastly comment on the possibility of ruling out minimal leptogenesis if these experiments find no signal.

  18. Traumatic orbital CSF leak

    Science.gov (United States)

    Borumandi, Farzad

    2013-01-01

    Compared to the cerebrospinalfluid (CSF) leak through the nose and ear, the orbital CSF leak is a rare and underreported condition following head trauma. We present the case of a 49-year-old woman with oedematous eyelid swelling and ecchymosis after a seemingly trivial fall onto the right orbit. Apart from the above, she was clinically unremarkable. The CT scan revealed a minimally displaced fracture of the orbital roof with no emphysema or intracranial bleeding. The fractured orbital roof in combination with the oedematous eyelid swelling raised the suspicion for orbital CSF leak. The MRI of the neurocranium demonstrated a small-sized CSF fistula extending from the anterior cranial fossa to the right orbit. The patient was treated conservatively and the lid swelling resolved completely after 5 days. Although rare, orbital CSF leak needs to be included in the differential diagnosis of periorbital swelling following orbital trauma. PMID:24323381

  19. Report of a consultants' meeting on a review of the methods used for leak rate measurements for WWER 440/230 confinements and WWER/440/213 containments. Extrabudgetary programme on the safety of WWER NPPS

    International Nuclear Information System (INIS)

    1995-01-01

    During the meeting the first two days were given to the presentations of the papers, after which the meeting was divided into working groups which prepared the experts' positions on the following topics: requirements of the National Regulatory Authorities on confinement/containment leak rate testing methods; local leak rate test methods; integral leak rate test methods; structural integrity testing; methods of evaluation of leak rate test results. The reports prepared by each working group were reviewed in plenary sessions and the final conclusions were discussed and agreed upon in the plenary meeting. 16 refs, 6 tabs

  20. DIGITAL FLOOD INSURANCE RATE MAP DATABASE, LEAKE COUNTY, MISSISSIPPI AND INCORPORATED AREAS

    Data.gov (United States)

    Federal Emergency Management Agency, Department of Homeland Security — The Digital Flood Insurance Rate Map (DFIRM) Database depicts flood risk information and supporting data used to develop the risk data. The primary risk...

  1. Standard practice for leaks using ultrasonics

    CERN Document Server

    American Society for Testing and Materials. Philadelphia

    2011-01-01

    1.1 Practice A, Pressurization—This practice covers procedures for calibration of ultrasonic instruments, location, and estimated measurements of gas leakage to atmosphere by the airborne ultrasonic technique. 1.2 In general practice this should be limited to leaks detected by two classifications of instruments, Class I and Class II. Class I instruments should have a minimum detectable leak rate of 6.7 × 10−7 mol/s (1.5 × 10−2 std. cm3/s at 0°C) or more for the pressure method of gas leakage to atmosphere. Class II instruments should have a minimal detectable leak rate of 6.7 × 10−6 mol/s (1.5 × 10−1 std. cm3/s at 0°C) or more for the pressure method of gas leakage to atmosphere. Refer to Guide E432 for additional information. 1.3 Practice B, Ultrasonic Transmitter—For object under test not capable of being pressurized but capable of having ultrasonic tone placed/injected into the test area to act as an ultrasonic leak trace source. 1.3.1 This practice is limited to leaks producing leakage o...

  2. Acceptance test procedure for the 105-KW isolation barrier leak rate

    International Nuclear Information System (INIS)

    McCracken, K.J.

    1995-01-01

    This acceptance test procedure shall be used to: First establish a basin water loss rate prior to installation of the two isolation barriers between the main basin and the discharge chute in K-Basin West. Second, perform an acceptance test to verify an acceptable leakage rate through the barrier seals. This Acceptance Test Procedure (ATP) has been prepared in accordance with CM-6-1 EP 4.2, Standard Engineering Practices

  3. Leaking Fuel Impacts and Practices

    International Nuclear Information System (INIS)

    Hozer, Zoltan; Szabo, Peter; Somfai, Barbara; Cherubini, Marco; Aldworth, Robin; Waeckel, Nicolas; Delorme, Tim; Dickson, Raymond; Fujii, Hajime; Rey Gayo, Jose Maria; Grant, Wade; Gorzel, Andreas; Hellwig, Christian; Kamimura, Katsuichiro; Sugiyama, Tomoyuki; Klouzal, Jan; Miklos, Marek; Nagase, Fumihisa; Nilsson, Marcus; Petit, Marc; Richards, Stuart; Lundqvist Saleh, Tobias; Stepniewski, Marek; Sim, Ki Seob; ); Rehacek, Radomir; Kissane, Martin; )

    2014-01-01

    The impact of leaking fuel rods on the operation of nuclear power plants and the practices of handling leaking fuel has been reviewed by the CSNI Working Group on Fuel Safety in order to promote a better understanding on the handling of leaking fuel in power reactors, as well as to discuss and review the current practices in member countries to help in decisions on the specification of reactor operation conditions with leaking fuel rods and on the handling of leaking fuel after removal from reactor. Experts from 15 countries provided data on the handling of leaking fuel in PWR, BWR, VVER and PHWR reactor types. The review covered the operation of NPP reactors with leaking fuel, wet and dry storage and transport of leaking assemblies. The methods and applied instruments to identify leaking fuel assemblies and the repair of them were addressed in the review. Special attention was paid to the activity release from leaking rods in the reactor and under storage conditions. The consideration of leaking fuel in safety analyses on core behaviour during postulated accidents was also discussed in the review. The main conclusions of the review pointed out that the activity release from leaking fuel rods in the reactor can be handled by technological systems, or in case of failure of too many rods the reactor can be shutdown to minimize activity release. Under accident conditions and operational transients the leaking rods may produce coolant activity concentration peaks. The storage of spent leaking fuel is normally characterised by moderate release of radionuclides from the fuel. The power plants apply limits for activity concentration to limit the amount of leaking rods in the core. In different countries, the accident analyses take into consideration the potential release from leaking fuel rods in design basis accidents in different ways. Some power plants apply special tools for handling and repair of leaking assemblies and rods. The leaking rods are stored together with

  4. Small liquid sodium leaks

    International Nuclear Information System (INIS)

    Dufresne, J.; Rochedereux, Y.; Antonakas, D.; Casselman, C.; Malet, J.C.

    1986-05-01

    Usually, pessimistic considerations inassessing the safety of secondary sodium loops in LMFBR reactor lead to assume guillotine rupture releasing a large amount of sodium estimate the consequences of large sodium fires. In order to reduce these consequences, one has to detect the smallest leak as soon as possible and to evaluate the future of an initial small leak. Analysis of the relationship between crack size and sodium outflow rate; Analysis of a sodium pipe with a small open crack

  5. Experimental simulation of low rate primary coolant leaks. For the case of vessel head penetrations affected by through wall cracking

    International Nuclear Information System (INIS)

    You, D.; Feron, D.; Turluer, G.

    2002-01-01

    An experimental simulation of primary coolant leaks was carried out to determine how the composition of the leaking liquid would change. The experiment used the EVA experimental setup, specially designed for quantitatively investigating concentration phenomena driven by evaporation. The test showed that the final composition, obtained from a solution representative of the primary coolant at the beginning of the cycle, is highly concentrated and slightly acid. The experimental results are compared with those obtained using the MULTEQ software. (authors)

  6. Correlations between deformations, surface state and leak rate in metal to metal contact; Correlations entre deformations, etat de surface et debit de fuite au contact metal-metal

    Energy Technology Data Exchange (ETDEWEB)

    Armand, G; Lapujoulade, J; Paigne, J [Commissariat a l' Energie Atomique, Saclay (France). Centre d' Etudes Nucleaires

    1963-07-01

    The study of metal to metal contact from the stand-point of the leak rate has been carried on a copper ring located between two hard-steel flanges. The analysis of the results confirms the hysteresis phenomenon already seen. Some curves (leak rate versus force and leak rate versus true deformation) in semi-logarithmic coordinates are straight lines. Likewise some curves (electrical contact resistance versus force) in bi-logarithmic coordinates are straight lines. All these results can be understood by looking at the conductance introduced by the deformations of the micro-geometry of the surfaces in contact. Some tests carried out in rising the temperature confirm these hypothesis. (authors) [French] L'etude du contact metal-metal du point de vue debit de fuite a ete poursuivie en utilisant un anneau de cuivre place entre brides d'acier dur. L'analyse des resultats confirme le phenomene d'hysteresis deja constate, montre l'influence de l'etat de surface des brides et du joint. Certaines courbes (debit de fuite/force et debit de fuite/deformation rationnelle), en coordonnees semi-logarithmiques, sont des droites. De meme, certaines courbes (resistance de contact/force) en coordonnees bi-logarithmiques, sont des droites. Ces resultats s'interpretent en considerant la conductance produite par la deformation des microgeometries des surfaces en contact. Quelques essais d'elevation de temperature confirment ces resultats. (auteurs)

  7. A Correlated Active Acoustic Leak Detection in a SFR Steam Generator

    International Nuclear Information System (INIS)

    Kim, Tae Joon; Jeong, Ji Young; Kim, Jong Man; Kim, Byung Ho; Kim, Yong Il

    2009-01-01

    The methods of acoustic leak detection are active acoustic leak detection and passive acoustic leak detection. The methods for passive acoustic leak detection are already established, but because our goal is development of passive acoustic leak detection for detecting a leakage range of small and micro leak rates, it is difficult detecting a leak in steam generator using this developed passive acoustic leak detection. Thus the acoustic leak detection system is required to be able to detect wide range of water leaks. From this view point we need to develop an active acoustic leak detection technology to be able to detect intermediate leak rates

  8. Preservation of the Myofascial Cuff During Posterior Fossa Surgery to Reduce the Rate of Pseudomeningocele Formation and Cerebrospinal Fluid Leak: A Technical Note.

    Science.gov (United States)

    Felbaum, Daniel R; Mueller, Kyle; Anaizi, Amjad; Mason, Robert B; Jean, Walter C; Voyadzis, Jean M

    2016-12-28

     Suboccipital craniotomy is a workhorse neurosurgical operation for approaching the posterior fossa but carries a high risk of pseudomeningocele and cerebrospinal fluid (CSF) leak. We describe our experience with a simple T-shaped fascial opening that preserves the occipital myofascial cuff as compared to traditional methods to reduce this risk.  A single institution, retrospective review of prospectively collected database was performed of patients that underwent a suboccipital craniectomy or craniotomy. Patient data was reviewed for craniotomy or craniectomy, dural graft, and/or sealant use as well as CSF complications. A pseudomeningocele was defined as a subcutaneous collection of cerebrospinal fluid palpable clinically and confirmed on imaging. A CSF leak was defined as a CSF-cutaneous fistula manifested by CSF leaking through the wound. All patients underwent regular postoperative visits of two weeks, one month, and three months.  Our retrospective review identified 33 patients matching the inclusion criteria. Overall, our cohort had a 21% (7/33) rate of clinical and radiographic pseudomeningocele formation with 9% (3/33) requiring surgical revision or a separate procedure. The rate of clinical and radiographic pseudomeningocele formation in the myofascial cuff preservation technique was less than standard techniques (12% and 31%, respectively). Revision or further surgical procedures were also reduced in the myofascial cuff preservation technique vs. the standard technique (6% vs 13%).  Preservation of the myofascial cuff during posterior fossa surgery is a simple and adoptable technique that reduces the rate of pseudomeningocele formation and CSF leak as compared with standard techniques.

  9. Device provides controlled gas leaks

    Science.gov (United States)

    Kami, S. K.; King, H. J.

    1968-01-01

    Modified palladium leak device provides a controlled release /leak/ of very small quantities of gas at low or medium pressures. It has no moving parts, requires less than 5 watts to operate, and is capable of releasing the gas either continuously or in pulses at adjustable flow rates.

  10. Intraoperative leak testing has no correlation with leak after laparoscopic sleeve gastrectomy.

    Science.gov (United States)

    Sethi, Monica; Zagzag, Jonathan; Patel, Karan; Magrath, Melissa; Somoza, Eduardo; Parikh, Manish S; Saunders, John K; Ude-Welcome, Aku; Schwack, Bradley F; Kurian, Marina S; Fielding, George A; Ren-Fielding, Christine J

    2016-03-01

    Staple line leak is a serious complication of sleeve gastrectomy. Intraoperative methylene blue and air leak tests are routinely used to evaluate for leak; however, the utility of these tests is controversial. We hypothesize that the practice of routine intraoperative leak testing is unnecessary during sleeve gastrectomy. A retrospective cohort study was designed using a prospectively collected database of seven bariatric surgeons from two institutions. All patients who underwent sleeve gastrectomy from March 2012 to November 2014 were included. The performance of intraoperative leak testing and the type of test (air or methylene blue) were based on surgeon preference. Data obtained included BMI, demographics, comorbidity, presence of intraoperative leak test, result of test, and type of test. The primary outcome was leak rate between the leak test (LT) and no leak test (NLT) groups. SAS version 9.4 was used for univariate and multivariate analyses. A total of 1550 sleeve gastrectomies were included; most were laparoscopic (99.8%), except for one converted and two open cases. Routine intraoperative leak tests were performed in 1329 (85.7%) cases, while 221 (14.3%) did not have LTs. Of the 1329 cases with LTs, there were no positive intraoperative results. Fifteen (1%) patients developed leaks, with no difference in leak rate between the LT and NLT groups (1 vs. 1%, p = 0.999). After adjusting for baseline differences between the groups with a propensity analysis, the observed lack of association between leak and intraoperative leak test remained. In this cohort, leaks presented at a mean of 17.3 days postoperatively (range 1-67 days). Two patients with staple line leaks underwent repeat intraoperative leak testing at leak presentation, and the tests remained negative. Intraoperative leak testing has no correlation with leak due to laparoscopic sleeve gastrectomy and is not predictive of the later development of staple line leak.

  11. Ultrasonic leak detection

    International Nuclear Information System (INIS)

    Murphy, R.V.

    1977-01-01

    A scanning ultrasonic microphone was used to detect the presence and locate the sources of hydraulic noises in piping systems in a reactor environment. The intensity changes of the noises correspond to changes of flow conditions within the system caused by throttled valves, flow rate changes, and leaks. (author)

  12. PFR evaporator leak

    International Nuclear Information System (INIS)

    Smedley, J.A.

    1975-01-01

    PFR has three heat removal circuits each one having an evaporator, superheater, reheater; all separate units. The status of the system was that circuit No 3 was steaming with 10 MW thermal nuclear power; No 1 circuit was filled with sodium but with the evaporator awaiting modification to cure gas entrainment problems already reported. The leak was in No 2 circuit and was located in the evaporator unit. The evaporator is rated at 120 M thermal at full power and as such is a large unit. The circuit was filled with both sodium and water for the first time three weeks before the conference so it was recent history being reported and therefore any figures quoted should be taken as indicative only. The history of the steam generator was that it was built at works to a very high standard and underwent all the usual tests of strength, inspection of welds and helium leak testing. The steam generator is of U tube design with a tube plate to which the boiler tubes are welded, with all the welds in one of two gas spaces. The inlet and outlet sides are separated by a baffle and the salient features are illustrated in the attached figure. The unit achieved a leak tightness better than the detection limit in the helium leak test at works. This limit was assessed as being less than an equivalent leak of 10 -6 g/s water under steam generator service conditions. However even though all the steam generator units passed this test at works a further test was carried out when the circuits had been completed. The test was carried out during commissioning after sodium filling and with the units hot. The method was to introduce a mixture of helium/ argon at 500 pounds/square inch into the water side of the steam generators and measure the helium concentration in the sodium side gas spaces of the circuit. The test lasted many days and under these conditions the sensitivity is such that a leak equivalent to somewhere between 10 -7 to 10 -6 g/s equivalent water leak could be detected, i

  13. PFR evaporator leak

    Energy Technology Data Exchange (ETDEWEB)

    Smedley, J A

    1975-07-01

    PFR has three heat removal circuits each one having an evaporator, superheater, reheater; all separate units. The status of the system was that circuit No 3 was steaming with 10 MW thermal nuclear power; No 1 circuit was filled with sodium but with the evaporator awaiting modification to cure gas entrainment problems already reported. The leak was in No 2 circuit and was located in the evaporator unit. The evaporator is rated at 120 M thermal at full power and as such is a large unit. The circuit was filled with both sodium and water for the first time three weeks before the conference so it was recent history being reported and therefore any figures quoted should be taken as indicative only. The history of the steam generator was that it was built at works to a very high standard and underwent all the usual tests of strength, inspection of welds and helium leak testing. The steam generator is of U tube design with a tube plate to which the boiler tubes are welded, with all the welds in one of two gas spaces. The inlet and outlet sides are separated by a baffle and the salient features are illustrated in the attached figure. The unit achieved a leak tightness better than the detection limit in the helium leak test at works. This limit was assessed as being less than an equivalent leak of 10{sup -6} g/s water under steam generator service conditions. However even though all the steam generator units passed this test at works a further test was carried out when the circuits had been completed. The test was carried out during commissioning after sodium filling and with the units hot. The method was to introduce a mixture of helium/ argon at 500 pounds/square inch into the water side of the steam generators and measure the helium concentration in the sodium side gas spaces of the circuit. The test lasted many days and under these conditions the sensitivity is such that a leak equivalent to somewhere between 10{sup -7} to 10{sup -6} g/s equivalent water leak could be

  14. Aerospace Payloads Leak Test Methodology

    Science.gov (United States)

    Lvovsky, Oleg; Grayson, Cynthia M.

    2010-01-01

    Pressurized and sealed aerospace payloads can leak on orbit. When dealing with toxic or hazardous materials, requirements for fluid and gas leakage rates have to be properly established, and most importantly, reliably verified using the best Nondestructive Test (NDT) method available. Such verification can be implemented through application of various leak test methods that will be the subject of this paper, with a purpose to show what approach to payload leakage rate requirement verification is taken by the National Aeronautics and Space Administration (NASA). The scope of this paper will be mostly a detailed description of 14 leak test methods recommended.

  15. The effects of fasting and cold exposure on metabolic rate and mitochondrial proton leak in liver and skeletal muscle of an amphibian, the cane toad Bufo marinus.

    Science.gov (United States)

    Trzcionka, M; Withers, K W; Klingenspor, M; Jastroch, M

    2008-06-01

    Futile cycling of protons across the mitochondrial inner membrane contributes significantly to standard metabolic rate in a variety of ectothermic and endothermic animals, but adaptations of the mitochondrial bioenergetics to different environmental conditions have rarely been studied in ectotherms. Changes in ambient temperature and nutritional status have a great effect on the physiological demands of ectothermic amphibians and may require the adjustment of mitochondrial efficiency. In order to investigate the effect of temperature and nutritional status on the mitochondrial level, we exposed male cane toads to either 10 degrees C or 30 degrees C and fasted half of the animals in each group. Cold exposure resulted in a fourfold reduction of the resting metabolic rate whereas nutritional status had only minor effects. The mitochondrial adjustments to each condition were observed by comparing the proton leak kinetics of isolated liver and skeletal muscle mitochondria at 25 degrees C. In response to cold exposure, liver mitochondria showed a decrease in proton conductance while skeletal muscle mitochondria were unchanged. Additional food deprivation had minor effects in skeletal muscle, but in liver we uncovered surprising differences in energy saving mechanisms between the acclimation temperatures: in warm-acclimated toads, fasting resulted in a decrease of the proton conductance whereas in cold-acclimated toads, the activity of the respiratory chain was reduced. To investigate the molecular mechanism underlying mitochondrial proton leakage, we determined the adenine-nucleotide transporter (ANT) content, which explained tissue-specific differences in the basal proton leak, but neither the ANT nor uncoupling protein (UCP) gene expression correlated with alterations of the proton leak in response to physiological stimuli.

  16. Leak Detection Modeling and Simulation for Oil Pipeline with Artificial Intelligence Method

    OpenAIRE

    Sukarno, Pudjo; Sidarto, Kuntjoro Adji; Trisnobudi, Amoranto; Setyoadi, Delint Ira; Rohani, Nancy; Darmadi, Darmadi

    2007-01-01

    Leak detection is always interesting research topic, where leak location and leak rate are two pipeline leaking parameters that should be determined accurately to overcome pipe leaking problems. In this research those two parameters are investigated by developing transmission pipeline model and the leak detection model which is developed using Artificial Neural Network. The mathematical approach needs actual leak data to train the leak detection model, however such data could not be obtained ...

  17. Prevention of intraoperative cerebrospinal fluid leaks by lumbar cerebrospinal fluid drainage during surgery for pituitary macroadenomas.

    Science.gov (United States)

    Mehta, Gautam U; Oldfield, Edward H

    2012-06-01

    Cerebrospinal fluid leakage is a major complication of transsphenoidal surgery. An intraoperative CSF leak, which occurs in up to 50% of pituitary tumor cases, is the only modifiable risk factor for postoperative leaks. Although several techniques have been described for surgical repair when an intraoperative leak is noted, none has been proposed to prevent an intraoperative CSF leak. The authors postulated that intraoperative CSF drainage would diminish tension on the arachnoid, decrease the rate of intraoperative CSF leakage during surgery for larger tumors, and reduce the need for surgical repair of CSF leaks. The results of 114 transsphenoidal operations for pituitary macroadenoma performed without intraoperative CSF drainage were compared with the findings from 44 cases in which a lumbar subarachnoid catheter was placed before surgery to drain CSF at the time of dural exposure and tumor removal. Cerebrospinal fluid drainage reduced the rate of intraoperative CSF leakage from 41% to 5% (p drainage reduced the need for operative repair (from 32% to 5%, p drainage during transsphenoidal surgery for macroadenomas reduces the rate of intraoperative CSF leaks. This preventative measure obviated the need for surgical repair of intraoperative CSF leaks using autologous fat graft placement, other operative techniques, postoperative lumbar drainage, and/or reoperation in most patients and is associated with minimal risks.

  18. Cost minimization analysis of high-dose-rate versus low-dose-rate brachytherapy in endometrial cancer

    International Nuclear Information System (INIS)

    Pinilla, James

    1998-01-01

    Purpose: Endometrial cancer is a common, usually curable malignancy whose treatment frequently involves low-dose-rate (LDR) or high-dose-rate (HDR) brachytherapy. These treatments involve substantial resource commitments and this is increasingly important. This paper presents a cost minimization analysis of HDR versus LDR brachytherapy in the treatment of endometrial cancer. Methods and Materials: The perspective of the analysis is that of the payor, in this case the Ministry of Health. One course of LDR treatment is compared to two courses of HDR treatment. The two alternatives are considered to be comparable with respect to local control, survival, and toxicities. Labor, overhead, and capital costs are accounted for and carefully measured. A 5% inflation rate is used where applicable. A univariate sensitivity analysis is performed. Results: The HDR regime is 22% less expensive compared to the LDR regime. This is $991.66 per patient or, based on the current workload of this department (30 patients per year) over the useful lifetime of the after loader, $297,498 over 10 years in 1997 dollars. Conclusion: HDR brachytherapy minimizes costs in the treatment of endometrial cancer relative to LDR brachytherapy. These results may be used by other centers to make rational decisions regarding brachytherapy equipment replacement or acquisition

  19. Leak Signature Space: An Original Representation for Robust Leak Location in Water Distribution Networks

    Directory of Open Access Journals (Sweden)

    Myrna V. Casillas

    2015-03-01

    Full Text Available In this paper, an original model-based scheme for leak location using pressure sensors in water distribution networks is introduced. The proposed approach is based on a new representation called the Leak Signature Space (LSS that associates a specific signature to each leak location being minimally affected by leak magnitude. The LSS considers a linear model approximation of the relation between pressure residuals and leaks that is projected onto a selected hyperplane. This new approach allows to infer the location of a given leak by comparing the position of its signature with other leak signatures. Moreover, two ways of improving the method’s robustness are proposed. First, by associating a domain of influence to each signature and second, through a time horizon analysis. The efficiency of the method is highlighted by means of a real network using several scenarios involving different number of sensors and considering the presence of noise in the measurements.

  20. Nonlinear radiative heat flux and heat source/sink on entropy generation minimization rate

    Science.gov (United States)

    Hayat, T.; Khan, M. Waleed Ahmed; Khan, M. Ijaz; Alsaedi, A.

    2018-06-01

    Entropy generation minimization in nonlinear radiative mixed convective flow towards a variable thicked surface is addressed. Entropy generation for momentum and temperature is carried out. The source for this flow analysis is stretching velocity of sheet. Transformations are used to reduce system of partial differential equations into ordinary ones. Total entropy generation rate is determined. Series solutions for the zeroth and mth order deformation systems are computed. Domain of convergence for obtained solutions is identified. Velocity, temperature and concentration fields are plotted and interpreted. Entropy equation is studied through nonlinear mixed convection and radiative heat flux. Velocity and temperature gradients are discussed through graphs. Meaningful results are concluded in the final remarks.

  1. The ISS 2B PVTCS Ammonia Leak: An Operational History

    Science.gov (United States)

    Vareha, Anthony

    2014-01-01

    In 2006, the Photovoltaic Thermal Control System (PVTCS) for the International Space Station's 2B power channel began leaking ammonia at a rate of approximately 1.5lbm/year (out of a starting approximately 53lbm system ammonia mass). Initially, the operations strategy was "feed the leak," a strategy successfully put into action via Extra Vehicular Activity during the STS-134 mission. During this mission the system was topped off with ammonia piped over from a separate thermal control system. This recharge was to have allowed for continued power channel operation into 2014 or 2015, at which point another EVA would have been required. Without these periodic EVAs to refill the 2B coolant system, the channel would eventually leak enough fluid as to risk pump cavitation and system failure, resulting in the loss of the 2B power channel - the most critical of the Space Station's 8 power channels. In mid-2012, the leak rate increased to approximately 5lbm/year. Once discovered, an EVA was planned and executed within a 5 week timeframe to drastically alter the architecture of the PVTCS via connection to a dormant thermal control system not intended to be utilized as anything other than spare components. The purpose of this rerouting of the TCS was to increase system volume and to isolate the photovoltaic radiator, thought to be the likely leak source. This EVA was successfully executed on November 1st, 2012 and left the 2B PVTCS in a configuration where the system was now being adequately cooled via a totally different radiator than what the system was designed to utilize. Unfortunately, data monitoring over the next several months showed that the isolated radiator was not leaking, and the system itself continued to leak steadily until May 9th, 2013. It was on this day that the ISS crew noticed the visible presence of ammonia crystals escaping from the 2B channel's truss segment, signifying a rapid acceleration of the leak from 5lbm/year to 5lbm/day. Within 48 hours of the

  2. Concentration device for leak liquids

    International Nuclear Information System (INIS)

    Matsumoto, Kaname; Matsuda, Ken; Takabori, Ken-ichi.

    1987-01-01

    Purpose: To improve radioactivity recovery and volume-reducing rates, as well as enable safety and easy handling for leak liquids resulted from reptures in coolant circuits. Constitution: The device of the invention comprises an evaporation vessel filled with leak fluids to a predetermined level, an airtight vessel disposed in the evaporation vessel containing hydrophilic porous material partially immersed in the leak fluids and means for heating the hydrophilic material. In this device, leak liquids are absorbed in the hydrophilic porous material, a great amount of water is evaporated from the outer surface of the hydrophilic porous material exposed above the liquid surface, and salts and radioactive material are remained on the inside and the outer surface of the porous material. The evaporated water content is condensated and recovered in a cooler and the remaining salts, etc. are discarded together with the porous material. The volume-reducing property can be improved by constituting the porous material with burnable material. (Takahashi, M.)

  3. Basis UST leak detection systems

    International Nuclear Information System (INIS)

    Silveria, V.

    1992-01-01

    This paper reports that gasoline and other petroleum products are leaking from underground storage tanks (USTs) at an alarming rate, seeping into soil and groundwater. Buried pipes are an even greater culprit, accounting for most suspected and detected leaks according to Environmental Protection Agency (EPA) estimates. In response to this problem, the EPA issued regulations setting standards for preventing, detecting, reporting, and cleaning up leaks, as well as fiscal responsibility. However, federal regulations are only a minimum; some states have cracked down even harder Plant managers and engineers have a big job ahead of them. The EPA estimates that there are more than 75,000 fuel USTs at US industrial facilities. When considering leak detection systems, the person responsible for making the decision has five primary choices: inventory reconciliation combined with regular precision tightness tests; automatic tank gauging; groundwater monitoring; interstitial monitoring of double containment systems; and vapor monitoring

  4. Minimizing transient influence in WHPA delineation: An optimization approach for optimal pumping rate schemes

    Science.gov (United States)

    Rodriguez-Pretelin, A.; Nowak, W.

    2017-12-01

    For most groundwater protection management programs, Wellhead Protection Areas (WHPAs) have served as primarily protection measure. In their delineation, the influence of time-varying groundwater flow conditions is often underestimated because steady-state assumptions are commonly made. However, it has been demonstrated that temporary variations lead to significant changes in the required size and shape of WHPAs. Apart from natural transient groundwater drivers (e.g., changes in the regional angle of flow direction and seasonal natural groundwater recharge), anthropogenic causes such as transient pumping rates are of the most influential factors that require larger WHPAs. We hypothesize that WHPA programs that integrate adaptive and optimized pumping-injection management schemes can counter transient effects and thus reduce the additional areal demand in well protection under transient conditions. The main goal of this study is to present a novel management framework that optimizes pumping schemes dynamically, in order to minimize the impact triggered by transient conditions in WHPA delineation. For optimizing pumping schemes, we consider three objectives: 1) to minimize the risk of pumping water from outside a given WHPA, 2) to maximize the groundwater supply and 3) to minimize the involved operating costs. We solve transient groundwater flow through an available transient groundwater and Lagrangian particle tracking model. The optimization problem is formulated as a dynamic programming problem. Two different optimization approaches are explored: I) the first approach aims for single-objective optimization under objective (1) only. The second approach performs multiobjective optimization under all three objectives where compromise pumping rates are selected from the current Pareto front. Finally, we look for WHPA outlines that are as small as possible, yet allow the optimization problem to find the most suitable solutions.

  5. Study on water leak-tightness of small leaks on a 1 inch cylinder valve

    International Nuclear Information System (INIS)

    Miyazawa, T.; Kasai, Y.; Inabe, N.; Aritomi, M.

    2002-01-01

    Practical thresholds for water leak-tightness of small leaks were determined by experimentation. Measurements for small leak samples were taken of air leakage rates and water leakage rates for identical leak samples in order to identify parameters that influence water leak-tightness threshold. Four types of leaks were evaluated: a fine wire inserted in an O-ring seal, a glass capillary tube, a stainless steel orifice, and a scratched valve stem on a 1 inch UF 6 cylinder valve. Experimental results demonstrated that the key parameter for water leak-tightness is the opening size of the leak hole. The maximum allowable hole size to achieve water leak-tightness ranged from 10 to 20 μm in diameter in this study. Experimental results with 1 inch UF 6 cylinder valve samples demonstrated that the acceptance criteria for preshipment leakage test, 1x10 -3 ref-cm 3 .s -1 , as prescribed in ANSI N14.5 is an appropriate value from the point of view of water leak-tightness for enriched UF 6 packages. The mechanism of water leak-tightness is plugging by tiny particles existing in water. The water used in experiments in this study contained far fewer particles than in water assumed to be encountered under accident conditions of transport. Therefore, the water leak-tightness threshold determined in this study is a conservative value in a practical evaluation. (author)

  6. Analysis of SX farm leak histories - Historical leak model (HLM)

    International Nuclear Information System (INIS)

    Fredenburg, E.A.

    1998-01-01

    This report uses readily available historical information to better define the volume, chemical composition, and Cs-137/Sr-90 amounts for leaks that have occurred in the past for tanks SX-108, SX-109, SX-111, and SX-112. In particular a Historical Leak Model (HLM) is developed that is a month by month reconciliation of tank levels, fill records, and calculated boil-off rates for these tanks. The HLM analysis is an independent leak estimate that reconstructs the tank thermal histories thereby deriving each tank's evaporative volume loss and by difference, its unaccounted losses as well. The HLM analysis was meant to demonstrate the viability of its approach, not necessarily to establish the HLM leak estimates as being definitive. Past leak estimates for these tanks have invariably resorted to soil wetting arguments but the extent of soil contaminated by each leak has always been highly uncertain. There is also a great deal of uncertainty with the HLM that was not quantified in this report, but will be addressed later. These four tanks (among others) were used from 1956 to 1975 for storage of high-level waste from the Redox process at Hanford. During their operation, tank waste temperatures were often as high as 150 C (300 F), but were more typically around 130 C. The primary tank cooling was by evaporation of tank waste and therefore periodic replacement of lost volume with water was necessary to maintain each tank's inventory. This active reflux of waste resulted in very substantial turnovers in tank inventory as well as significant structural degradation of these tanks. As a result of the loss of structural integrity, each of these tanks leaked during their active periods of operation. Unfortunately, the large turnover in tank volume associated with their reflux cooling has made a determination of leak volumes very difficult. During much of these tanks operational histories, inventory losses because of evaporative cooling could have effectively masked any volume

  7. Leak detection capability in CANDU reactors

    International Nuclear Information System (INIS)

    Azer, N.; Barber, D.H.; Boucher, P.J.

    1997-01-01

    This paper addresses the moisture leak detection capability of Ontario Hydro CANDU reactors which has been demonstrated by performing tests on the reactor. The tests confirmed the response of the annulus gas system (AGS) to the presence of moisture injected to simulate a pressure tube leak and also confirmed the dew point response assumed in leak before break assessments. The tests were performed on Bruce A Unit 4 by injecting known and controlled rates of heavy water vapor. To avoid condensation during test conditions, the amount of moisture which could be injected was small (2-3.5 g/hr). The test response demonstrated that the AGS is capable of detecting and annunciating small leaks. Thus confidence is provided that it would alarm for a growing pressure tube leak where the leak rate is expected to increase to kg/hr rapidly. The measured dew point response was close to that predicted by analysis

  8. Leak detection capability in CANDU reactors

    Energy Technology Data Exchange (ETDEWEB)

    Azer, N.; Barber, D.H.; Boucher, P.J. [and others

    1997-04-01

    This paper addresses the moisture leak detection capability of Ontario Hydro CANDU reactors which has been demonstrated by performing tests on the reactor. The tests confirmed the response of the annulus gas system (AGS) to the presence of moisture injected to simulate a pressure tube leak and also confirmed the dew point response assumed in leak before break assessments. The tests were performed on Bruce A Unit 4 by injecting known and controlled rates of heavy water vapor. To avoid condensation during test conditions, the amount of moisture which could be injected was small (2-3.5 g/hr). The test response demonstrated that the AGS is capable of detecting and annunciating small leaks. Thus confidence is provided that it would alarm for a growing pressure tube leak where the leak rate is expected to increase to kg/hr rapidly. The measured dew point response was close to that predicted by analysis.

  9. Paravalvular Leak in Structural Heart Disease.

    Science.gov (United States)

    Goel, Kashish; Eleid, Mackram F

    2018-03-06

    This review will summarize the growing importance of diagnosing and managing paravalvular leak associated with surgical and transcatheter valves. The burden of paravalvular leak is increasing; however, advanced imaging techniques and high degree of clinical suspicion are required for diagnosis and management. The latest data from pivotal clinical trials in the field of transcatheter aortic valve replacement suggest that any paravalvular leak greater than mild was associated with worse clinical outcomes. Percutaneous techniques for paravalvular leak closure are now the preferred approach, and surgical repair is reserved for contraindications and unsuccessful procedures. Recent data from studies evaluating paravalvular leak closure outcomes report a greater than 90% success rate with a significant improvement in patient symptoms. Paravalvular leak is a growing problem in the structural heart disease arena. Percutaneous closure is successful in more than 90% of the procedures with a low complication rate.

  10. Improved method of measurement for outer leak

    International Nuclear Information System (INIS)

    Xu Guang

    2012-01-01

    Pneumatic pipeline is installed for the airborne radioactivity measurement equipment, air tightness and outer leak rate are essential for the testing of the characteristics, both in the national criteria and ISO standards, an improved practical method is available for the measurement of the outer air leak rate based on the engineering experiences for the equipment acceptance and testing procedure. (authors)

  11. Small sodium-to-gas leak behavior in relation to LMFBR leak detection system design

    International Nuclear Information System (INIS)

    Hopenfeld, J.; Taylor, G.R.; James, L.A.

    1976-01-01

    Various aspects of sodium-to-gas leaks which must be considered in the design of leak detection systems for LMFBR's are discussed. Attention is focused primarily on small, weeping type leaks. Corrosion rates of steels in fused sodium hydroxide and corrosion damage observed at the site of small leaks lead to the conclusion that the sodium-gas reaction products could attack the primary hot leg piping at rates up to 0.08 mils per hour. Based on theoretical considerations of the corrosion mechanism and on visual observations of pipe topography following small sodium leak tests, it is concluded that pipe damage will be manifested by the formation of small detectable leaks prior to the appearance of larger leaks. The case for uniform pipe corrosion along the pipe circumference or along a vertical section of the pipe is also examined. Using a theoretical model for the gravity flow of sodium and reaction products along the pipe surface and a mass transport controlled corrosion process, it is shown that below sodium leak rates of about 30 g/hr for the primary piping corrosion damage will not extend beyond one radius distance from the leak site. A method of estimating the time delay between the initiation of such leaks and the development of a larger leak due to increased pipe stresses resulting from corrosion is presented

  12. Quantitative Rates of Brain Glucose Metabolism Distinguish Minimally Conscious from Vegetative State Patients

    DEFF Research Database (Denmark)

    Stender, Johan; Kupers, Ron; Rodell, Anders

    2015-01-01

    of these patients. However, no quantitative comparisons of cerebral glucose metabolism in VS/UWS and MCS have yet been reported. We calculated the regional and whole-brain CMRglc of 41 patients in the states of VS/UWS (n=14), MCS (n=21) or emergence from MCS (EMCS, n=6), and healthy volunteers (n=29). Global......The differentiation of the vegetative or unresponsive wakefulness syndrome (VS/UWS) from the minimally conscious state (MCS) is an important clinical issue. The cerebral metabolic rate of glucose (CMRglc) declines when consciousness is lost, and may reveal the residual cognitive function...... these results reveal a significant correlation between whole-brain energy metabolism and level of consciousness, suggesting that quantitative values of CMRglc reveal consciousness in severely brain-injured patients.Journal of Cerebral Blood Flow & Metabolism advance online publication, 8 October 2014; doi:10...

  13. From b → sγ to the LSP detection rates in minimal string unification models

    International Nuclear Information System (INIS)

    Khalil, S.; Masiero, A.; Shafi, Q.

    1997-04-01

    We exploit the measured branching ratio for b → sγ to derive lower limits on the sparticle and Higgs masses in the minimal string unification models. For the LSP ('bino'), chargino and the lightest Higgs, these turn out to be 50, 90 and 75 GeV respectively. Taking account of the upper bounds on the mass spectrum from the LSP relic abundance, we estimate the direct detection rate for the latter to vary from 10 -1 to 10 -4 events/kg/day. The muon flux, produced by neutrinos from the annihilating LSP's, varies in the range 10 -2 - 10 -9 muons/m 2 /day. (author). 26 refs, 9 figs

  14. Hermetic compartments leak-tightness enhancement

    International Nuclear Information System (INIS)

    Murani, J.

    2000-01-01

    In connection with the enhancement of the nuclear safety of the Jaslovske Bohunice V-1 NPP actions for the increase of the leak tightness are performed. The reconstruction has been done in the following directions: hermetic compartments leak tightness enhancement; air lock installation; installation of air lock in SP 4 vent system; integrated leakage rate test to hermetic compartments with leak detection. After 'major' leaks on the hermetic boundary components had been eliminated, since 1994 works on a higher qualitative level began. The essence of the works consists in the detection and identification of leaks in the structural component of the hermetic boundary during the planned refueling outages. The results of the Small Reconstruction and gradual enhancement of leak tightness are presented

  15. Quantitative rates of brain glucose metabolism distinguish minimally conscious from vegetative state patients.

    Science.gov (United States)

    Stender, Johan; Kupers, Ron; Rodell, Anders; Thibaut, Aurore; Chatelle, Camille; Bruno, Marie-Aurélie; Gejl, Michael; Bernard, Claire; Hustinx, Roland; Laureys, Steven; Gjedde, Albert

    2015-01-01

    The differentiation of the vegetative or unresponsive wakefulness syndrome (VS/UWS) from the minimally conscious state (MCS) is an important clinical issue. The cerebral metabolic rate of glucose (CMRglc) declines when consciousness is lost, and may reveal the residual cognitive function of these patients. However, no quantitative comparisons of cerebral glucose metabolism in VS/UWS and MCS have yet been reported. We calculated the regional and whole-brain CMRglc of 41 patients in the states of VS/UWS (n=14), MCS (n=21) or emergence from MCS (EMCS, n=6), and healthy volunteers (n=29). Global cortical CMRglc in VS/UWS and MCS averaged 42% and 55% of normal, respectively. Differences between VS/UWS and MCS were most pronounced in the frontoparietal cortex, at 42% and 60% of normal. In brainstem and thalamus, metabolism declined equally in the two conditions. In EMCS, metabolic rates were indistinguishable from those of MCS. Ordinal logistic regression predicted that patients are likely to emerge into MCS at CMRglc above 45% of normal. Receiver-operating characteristics showed that patients in MCS and VS/UWS can be differentiated with 82% accuracy, based on cortical metabolism. Together these results reveal a significant correlation between whole-brain energy metabolism and level of consciousness, suggesting that quantitative values of CMRglc reveal consciousness in severely brain-injured patients.

  16. Acoustic surveillance techniques for SGU leak monitoring

    International Nuclear Information System (INIS)

    McKnight, J.A.; Rowley, R.; Beesley, M.J.

    1990-01-01

    The paper presents a brief review of the acoustic techniques applicable to the detection of steam generator unit leaks that have been studied in the UK. Before discussion of the acoustic detection methods a reference representation of the required performance as developed in the UK is given. The conclusion is made that preliminary specification for the acoustic leak detection of sodium/water leaks in steam generating units suggests that it will be necessary to detect better than a leak rate of 3 g/s within a few seconds. 10 refs, 12 figs

  17. Leak detection : Principles and practice

    International Nuclear Information System (INIS)

    Rama Rao, V.V.K.

    1981-01-01

    Principles of leak detection are explained and various aspects of leak detection techniques and leak detectors are reviewed. The review covers: units for leaks and leak tightness, classification of leaks, timing of leak testing, designing for ease of leak testing of any job, methods of leak detection, their ranges of application and limitations, leak detectors, response time of leak test, minimum detectable concentration of search gas during leak tests, and validity of leak tests. Helium mass spectrometer type leak detector and technique are described in detail. Recent improvements in leak detectors and techniques, particularly mass spectrometer leak detectors using gases other than helium (e.g. hydrogen, argon) are also covered in the review. (M.G.B.)

  18. ISOLDE Off-line Gas Leak Upgrade

    CERN Document Server

    Nielsen, Kristoffer Bested

    2017-01-01

    This study investigates gas injection system of the ISOLDE Off-line separator. A quadrupole mass spectrometer is used to analysis the composition of the gas. Based on these measurements a contamination of the injected gas is found and a system upgrade is purposed. Furthermore a calibration of the leak rate of the leak valve is made.

  19. Time Domain Equalizer Design Using Bit Error Rate Minimization for UWB Systems

    Directory of Open Access Journals (Sweden)

    Syed Imtiaz Husain

    2009-01-01

    Full Text Available Ultra-wideband (UWB communication systems occupy huge bandwidths with very low power spectral densities. This feature makes the UWB channels highly rich in resolvable multipaths. To exploit the temporal diversity, the receiver is commonly implemented through a Rake. The aim to capture enough signal energy to maintain an acceptable output signal-to-noise ratio (SNR dictates a very complicated Rake structure with a large number of fingers. Channel shortening or time domain equalizer (TEQ can simplify the Rake receiver design by reducing the number of significant taps in the effective channel. In this paper, we first derive the bit error rate (BER of a multiuser and multipath UWB system in the presence of a TEQ at the receiver front end. This BER is then written in a form suitable for traditional optimization. We then present a TEQ design which minimizes the BER of the system to perform efficient channel shortening. The performance of the proposed algorithm is compared with some generic TEQ designs and other Rake structures in UWB channels. It is shown that the proposed algorithm maintains a lower BER along with efficiently shortening the channel.

  20. Minimizing the symbol-error-rate for amplify-and-forward relaying systems using evolutionary algorithms

    KAUST Repository

    Ahmed, Qasim Zeeshan

    2015-02-01

    In this paper, a new detector is proposed for an amplify-and-forward (AF) relaying system. The detector is designed to minimize the symbol-error-rate (SER) of the system. The SER surface is non-linear and may have multiple minimas, therefore, designing an SER detector for cooperative communications becomes an optimization problem. Evolutionary based algorithms have the capability to find the global minima, therefore, evolutionary algorithms such as particle swarm optimization (PSO) and differential evolution (DE) are exploited to solve this optimization problem. The performance of proposed detectors is compared with the conventional detectors such as maximum likelihood (ML) and minimum mean square error (MMSE) detector. In the simulation results, it can be observed that the SER performance of the proposed detectors is less than 2 dB away from the ML detector. Significant improvement in SER performance is also observed when comparing with the MMSE detector. The computational complexity of the proposed detector is much less than the ML and MMSE algorithms. Moreover, in contrast to ML and MMSE detectors, the computational complexity of the proposed detectors increases linearly with respect to the number of relays.

  1. Minimally allowed neutrinoless double beta decay rates within an anarchical framework

    International Nuclear Information System (INIS)

    Jenkins, James

    2009-01-01

    Neutrinoless double beta decay (ββ0ν) is the only realistic probe of the Majorana nature of the neutrino. In the standard picture, its rate is proportional to m ee , the e-e element of the Majorana neutrino mass matrix in the flavor basis. I explore minimally allowed m ee values within the framework of mass matrix anarchy where neutrino parameters are defined statistically at low energies. Distributions of mixing angles are well defined by the Haar integration measure, but masses are dependent on arbitrary weighting functions and boundary conditions. I survey the integration measure parameter space and find that for sufficiently convergent weightings, m ee is constrained between (0.01-0.4) eV at 90% confidence. Constraints from neutrino mixing data lower these bounds. Singular integration measures allow for arbitrarily small m ee values with the remaining elements ill-defined, but this condition constrains the flavor structure of the model's ultraviolet completion. ββ0ν bounds below m ee ∼5x10 -3 eV should indicate symmetry in the lepton sector, new light degrees of freedom, or the Dirac nature of the neutrino.

  2. A proposed structural, risk-informed approach to the periodicity of CANDU-6 nuclear containment integrated leak rate testing

    Energy Technology Data Exchange (ETDEWEB)

    Saliba, N. [McGill Univ., Dept. of Civil Engineering and Applied Mechanics, Montreal, Quebec (Canada); Komljenovic, D. [Hydro-Quebec, Gentilly-2 Nuclear Power Plant, Becancour, Quebec (Canada); Chouinard, L. [McGill Univ., Dept. of Civil Engineering and Applied Mechanics, Montreal, Quebec (Canada); Vaillancourt, R.; Chretien, G. [Hydro-Quebec, Gentilly-2 Nuclear Power Plant, Becancour, Quebec (Canada); Gocevski, V. [Hydro-Quebec Equipements, Montreal, Quebec (Canada)

    2010-07-01

    As ultimate lines of defense against leakage of large amounts of radioactive material to the environment in case of major reactor accidents, containments have been monitored through well designed periodic tests to ensure their proper performance. Regulatory organizations have imposed types and frequencies of containment tests based on highly-conservative deterministic approaches, and judgments of knowledgeable experts. Recent developments in the perception and methods of risk evaluation have been applied to rationalize the leakage-rate testing frequencies while maintaining risks within acceptable levels, preserving the integrity of containments, and respecting the defense-in-depth philosophy. The objective of this paper is to introduce a proposed risk-informed decision making framework on the periodicity of nuclear containment ILRTs for CANDU-6 nuclear power plants based on five main decision criteria, namely: 1) the containment structural integrity; 2) inputs from PSA Level-2; 3) the requirements of deterministic safety analyses and defense-in-depth concepts; 4- the obligations under regulatory and standard requirements; and 5) the return of experience from nuclear containments historic performance. The concepts of dormant reliability and structural fragility will guide the assessment of the containment structural integrity, within the general context of a global containment life cycle management program. This study is oriented towards the requirements of CANDU-6 reactors, in general, and Hydro-Quebec's Gentilly-2 nuclear power plant, in particular. The present article is the first part in a series of papers that will comprehensively detail the proposed research. (author)

  3. A proposed structural, risk-informed approach to the periodicity of CANDU-6 nuclear containment integrated leak rate testing

    International Nuclear Information System (INIS)

    Saliba, N.; Komljenovic, D.; Chouinard, L.; Vaillancourt, R.; Chretien, G.; Gocevski, V.

    2010-01-01

    As ultimate lines of defense against leakage of large amounts of radioactive material to the environment in case of major reactor accidents, containments have been monitored through well designed periodic tests to ensure their proper performance. Regulatory organizations have imposed types and frequencies of containment tests based on highly-conservative deterministic approaches, and judgments of knowledgeable experts. Recent developments in the perception and methods of risk evaluation have been applied to rationalize the leakage-rate testing frequencies while maintaining risks within acceptable levels, preserving the integrity of containments, and respecting the defense-in-depth philosophy. The objective of this paper is to introduce a proposed risk-informed decision making framework on the periodicity of nuclear containment ILRTs for CANDU-6 nuclear power plants based on five main decision criteria, namely: 1) the containment structural integrity; 2) inputs from PSA Level-2; 3) the requirements of deterministic safety analyses and defense-in-depth concepts; 4- the obligations under regulatory and standard requirements; and 5) the return of experience from nuclear containments historic performance. The concepts of dormant reliability and structural fragility will guide the assessment of the containment structural integrity, within the general context of a global containment life cycle management program. This study is oriented towards the requirements of CANDU-6 reactors, in general, and Hydro-Quebec's Gentilly-2 nuclear power plant, in particular. The present article is the first part in a series of papers that will comprehensively detail the proposed research. (author)

  4. Sensors for Fluid Leak Detection

    Directory of Open Access Journals (Sweden)

    Gonzalo Pajares Martinsanz

    2015-02-01

    Full Text Available Fluid leak detection represents a problem that has attracted the interest of researchers, but not exclusively because in industries and services leaks are frequently common. Indeed, in water or gas supplies, chemical or thermal plants, sea-lines or cooling/heating systems leakage rates can cause important economic losses and sometimes, what it is more relevant, environmental pollution with human, animal or plant lives at risk. This last issue has led to increased national and international regulations with different degrees of severity regarding environmental conservation.[...

  5. On the helium gas leak test

    International Nuclear Information System (INIS)

    Nishikawa, Akira; Ozaki, Susumu

    1975-01-01

    The helium gas leak test (Helium mass spectrometer testing) has a leak detection capacity of the highest level in practical leak tests and is going to be widely applied to high pressure vessels, atomic and vacuum equipments that require high tightness. To establish a standard test procedure several series of experiments were conducted and the results were investigated. The conclusions are summarized as follows: (1) The hood method is quantitatively the most reliable method. The leak rate obtained by tests using 100% helium concentration should be the basis of the other method of test. (2) The integrating method, bell jar method, and vacuum spray method can be considered quantitative when particular conditions are satisfied. (3) The sniffer method is not to be considered quantitive. (4) The leak rate of the hood, integrating, and bell jar methods is approximately proportional to the square of the helium partial pressure. (auth.)

  6. Performance evaluation of PFBR wire type sodium leak detectors

    International Nuclear Information System (INIS)

    Vijayakumar, G.; Rajan, K.K.; Nashine, B.K.; Chandramouli, S.; Madhusoodanan, K.; Kalyanasundaram, P.

    2011-01-01

    Highlights: → Performance evaluation of wire type leak detectors was conducted in LEENA facility by creating sodium leaks. → The lowest leak rate of 214 g/h was detected in 50 min and the highest detection time was 6 h for a leak rate of 222 g/h. → Factors affecting the leak detection time are packing density of thermal insulation, layout of heater, temperature, etc. → Relationship between leak rate and detection time was established and a leak rate of 100 g/h is likely to be detected in 11.1 h. → Contact resistance of leaked sodium increased to 3.5 kilo ohms in 20 h. - Abstract: Wire type leak detectors working on conductivity principle are used for detecting sodium leak in the secondary sodium circuits of fast breeder reactors. It is required to assess the performance of these detectors and confirm that they are meeting the requirements. A test facility by name LEENA was constructed at Indira Gandhi Centre for Atomic Research (IGCAR), Kalpakkam to test the wire type leak detector lay out by simulating different sodium leak rates. This test facility consists of a sodium dump tank, a test vessel, interconnecting pipelines with valves, micro filter and test section with leak simulators. There are three different test sections in the test set up of length 1000 mm each. These test sections simulate piping of Prototype Fast Breeder Reactor (PFBR) secondary circuit and the wire type leak detector layout in full scale. All test sections are provided with leak simulators. A leak simulator consists of a hole of size one mm drilled in the test section and closed with a tapered pin. The tapered pin position in the hole is adjusted by a screw mechanism and there by the annular gap of flow area is varied for getting different leak rates. Various experiments were conducted to evaluate the performance of the leak detectors by creating different sodium leak rates. This paper deals with the details of wire type leak detector layout for the secondary sodium circuit of

  7. Developments in steam generator leak detection at Ontario Hydro

    Energy Technology Data Exchange (ETDEWEB)

    Maynard, K.J.; Singh, V.P. [Ontario Hydro Technologies, Toronto, Ontario (Canada)

    1998-07-01

    A method for locating small tube leaks in steam generators has been developed and implemented at Ontario Hydro. The technique utilizes both helium leak detection and moisture leak detection. The combination of these two methods allows tube leaks to be detected in any part of the tube bundle, including those submerged below water near the tubesheet. The estimated detection limits for the helium and moisture leak detection systems are 0.001 kg/hr and 0.05 kg/hr respectively, expressed as leak rates measured at typical boiler operating conditions. This technology is best utilized in situations where the leak rate under operating conditions is smaller than the practical limit for fluorescein dye techniques ({approx}2 kg/hour). Other novel techniques have been utilized to increase the reliability and speed of the boiler leak search process. These include the use of argon carrier gas to stabilize the buoyant helium gas in the boiler secondary. (author)

  8. Developments in steam generator leak detection at Ontario Hydro

    International Nuclear Information System (INIS)

    Maynard, K.J.; Singh, V.P.

    1998-01-01

    A method for locating small tube leaks in steam generators has been developed and implemented at Ontario Hydro. The technique utilizes both helium leak detection and moisture leak detection. The combination of these two methods allows tube leaks to be detected in any part of the tube bundle, including those submerged below water near the tubesheet. The estimated detection limits for the helium and moisture leak detection systems are 0.001 kg/hr and 0.05 kg/hr respectively, expressed as leak rates measured at typical boiler operating conditions. This technology is best utilized in situations where the leak rate under operating conditions is smaller than the practical limit for fluorescein dye techniques (∼2 kg/hour). Other novel techniques have been utilized to increase the reliability and speed of the boiler leak search process. These include the use of argon carrier gas to stabilize the buoyant helium gas in the boiler secondary. (author)

  9. Automated method for determining location and magnitude of leaks inside a PWR containment

    International Nuclear Information System (INIS)

    Cho, J.H.; Elia, F.A. Jr.

    1986-01-01

    Thermal-hydraulics analysis can be used to determine location and magnitude of leaks inside a pressurized water reactor (PWR) containment, as required by plant technical specifications. The major advantage of this detection method is that it minimizes radiation exposure of maintenance personnel because most of the leak detection process is performed from the control room outside the containment. In addition, such a program allows for the elimination of pipe whip restraints and jet impingement shields, eliminating costs for maintenance of these supports and shields in older plants and lowering construction costs for new plants. Previously, only simple single-node containment models were used for determining leakage magnitude. This paper presents a more sophisticated multinode approach for determining the magnitude and location. The resulting sensitivities to leak can be programmed into the plant's computer system. In this way, the plant's computer will be able to measure and locate leaks inside containment. The study concludes that dew point temperature (or relative humidity) is the most suitable parameter for locating a leak while flow rate to sump is the most suitable parameter for quantifying the leak

  10. Study on Leak Detection of the Pipeline System by Acoustic Emission

    International Nuclear Information System (INIS)

    Yoon, D. J.; Kim, C. J.

    1987-01-01

    Leak detection testing for the pipeline system was performed by the acoustic emission method. It was found that the detected signal spectrum was influenced by the frequency response of sensors and pressure changes. AE parameters and frequency spectrum distributions were used to analyze the leak signals. The slope rise time of AE parameters were the important factors for distinguishing leak signals. The amplitude of leak signal was more affected by the changes of leak, rate and pressure than those of leak type

  11. Humos monitoring system of leaks in to the containment atmosphere

    International Nuclear Information System (INIS)

    Matal, O.; Zaloudek, J.; Matal, O. Jr.; Klinga, J.; Brom, J.

    1997-01-01

    HUmidity MOnitoring System (HUMOS) has been developed and designed to detect the presence of leak in selected primary circuit high energy pipelines and components that are evaluated from the point of view of Leak Before Break (LBB) requirements. It also requires to apply technical tools for detection and identification of coolant leaks from primary circuit and components of PWRs reactors. Safety significant of leaks depend on: leak source (location); leak rate, and leak duration. Therefore to detect and monitor coolant leaks in to the containment atmosphere during reactor operation is one of important safety measures. As potential leak sources flange connection in the upper head region of WWER reactors can be considered. HUMOS does not rely on the release of radioactivity to detect leaks but rather the relies on detection of moisture in the air resulting from a primary boundary leak. Because HUMOS relies on moisture and temperature detection, leaks can be detected without requiring the reactor to be critical. Therefore leaks can be detected during integrity pressure tests and any other mode of operation provided the reactor ventilation system is operating and primary circuit and components are pressurized. 3 figs

  12. A Hybrid Heuristic Optimization Approach for Leak Detection in Pipe Networks Using Ordinal Optimization Approach and the Symbiotic Organism Search

    Directory of Open Access Journals (Sweden)

    Chao-Chih Lin

    2017-10-01

    Full Text Available A new transient-based hybrid heuristic approach is developed to optimize a transient generation process and to detect leaks in pipe networks. The approach couples the ordinal optimization approach (OOA and the symbiotic organism search (SOS to solve the optimization problem by means of iterations. A pipe network analysis model (PNSOS is first used to determine steady-state head distribution and pipe flow rates. The best transient generation point and its relevant valve operation parameters are optimized by maximizing the objective function of transient energy. The transient event is created at the chosen point, and the method of characteristics (MOC is used to analyze the transient flow. The OOA is applied to sift through the candidate pipes and the initial organisms with leak information. The SOS is employed to determine the leaks by minimizing the sum of differences between simulated and computed head at the observation points. Two synthetic leaking scenarios, a simple pipe network and a water distribution network (WDN, are chosen to test the performance of leak detection ordinal symbiotic organism search (LDOSOS. Leak information can be accurately identified by the proposed approach for both of the scenarios. The presented technique makes a remarkable contribution to the success of leak detection in the pipe networks.

  13. Routine intraoperative leak testing for sleeve gastrectomy: is the leak test full of hot air?

    Science.gov (United States)

    Bingham, Jason; Lallemand, Michael; Barron, Morgan; Kuckelman, John; Carter, Preston; Blair, Kelly; Martin, Matthew

    2016-05-01

    Staple line leak after sleeve gastrectomy (SG) is a rare but dreaded complication with a reported incidence of 0% to 8%. Many surgeons routinely test the staple line with an intraoperative leak test (IOLT), but there is little evidence to validate this practice. In fact, there is a theoretical concern that the leak test may weaken the staple line and increase the risk of a postop leak. Retrospective review of all SGs performed over a 7-year period was conducted. Cases were grouped by whether an IOLT was performed, and compared for the incidence of postop staple line leaks. The ability of the IOLT for identifying a staple line defect and for predicting a postoperative leak was analyzed. Five hundred forty-two SGs were performed between 2007 and 2014. Thirteen patients (2.4%) developed a postop staple line leak. The majority of patients (n = 494, 91%) received an IOLT, including all 13 patients (100%) who developed a subsequent clinical leak. There were no (0%) positive IOLTs and no additional interventions were performed based on the IOLT. The IOLT sensitivity and positive predictive value were both 0%. There was a trend, although not significant, to increase leak rates when a routine IOLT was performed vs no routine IOLT (2.6% vs 0%, P = .6). The performance of routine IOLT after SG provided no actionable information, and was negative in all patients who developed a postoperative leak. The routine use of an IOLT did not reduce the incidence of postop leak, and in fact was associated with a higher leak rate after SG. Published by Elsevier Inc.

  14. Front end power dissipation minimization and optimal transmission rate for wireless receivers

    NARCIS (Netherlands)

    Heuvel, van den J.H.C.; Wu, Y.; Baltus, P.G.M.; Linnartz, J.P.M.G.; Roermund, van A.H.M.

    2014-01-01

    Most wireless battery-operated devices spend more energy receiving than transmitting. Hence, minimizing the power dissipation in the receiver front end, which, in many cases, is the prominent power consuming part of the receiver, is an important challenge. This paper addresses this challenge by

  15. Benign Biliary Strictures and Leaks.

    Science.gov (United States)

    Devière, Jacques

    2015-10-01

    The major causes of benign biliary strictures include surgery, chronic pancreatitis, primary sclerosing cholangitis, and autoimmune cholangitis. Biliary leaks mainly occur after surgery and, rarely, abdominal trauma. These conditions may benefit from a nonsurgical approach in which endoscopic retrograde cholangiopancreatography (ERCP) plays a pivotal role in association with other minimally invasive approaches. This approach should be evaluated for any injury before deciding about the method for repair. ERCP, associated with peroral cholangioscopy, plays a growing role in characterizing undeterminate strictures, avoiding both unuseful major surgeries and palliative options that might compromise any further management. Copyright © 2015 Elsevier Inc. All rights reserved.

  16. Leak detection method

    International Nuclear Information System (INIS)

    1978-01-01

    This invention provides a method for removing nuclear fuel elements from a fabrication building while at the same time testing the fuel elements for leaks without releasing contaminants from the fabrication building or from the fuel elements. The vacuum source used, leak detecting mechanism and fuel element fabrication building are specified to withstand environmental hazards. (UK)

  17. Bit Error Rate Minimizing Channel Shortening Equalizers for Single Carrier Cyclic Prefixed Systems

    National Research Council Canada - National Science Library

    Martin, Richard K; Vanbleu, Koen; Ysebaert, Geert

    2007-01-01

    .... Previous work on channel shortening has largely been in the context of digital subscriber lines, a wireline system that allows bit allocation, thus it has focused on maximizing the bit rate for a given bit error rate (BER...

  18. Preservation of the Myofascial Cuff During Posterior Fossa Surgery to Reduce the Rate of Pseudomeningocele Formation and Cerebrospinal Fluid Leak: A Technical Note

    OpenAIRE

    Felbaum, Daniel R; Mueller, Kyle; Anaizi, Amjad; Mason, Robert B; Jean, Walter C; Voyadzis, Jean M

    2016-01-01

    Introduction:?Suboccipital craniotomy is a workhorse neurosurgical operation for approaching the posterior fossa?but carries a high risk of pseudomeningocele and cerebrospinal fluid (CSF) leak. We describe our experience with a simple T-shaped fascial opening that preserves the occipital myofascial cuff as compared to traditional methods to reduce this risk. Methods:?A single institution, retrospective review of prospectively collected database was performed of patients that underwent a suboc...

  19. The world is polluted with leaked cyber data

    CSIR Research Space (South Africa)

    Burke, Ivan D

    2017-10-01

    Full Text Available Data breaches are becoming more common and numerous every day, where huge amount of data (corporate and personal) are leaked more frequently than ever. Corporate responses to data breaches are insufficient, when commonly remediation is minimal...

  20. Postoperative ascitic leaks: the ongoing challenge.

    Science.gov (United States)

    Rosemurgy, A S; Statman, R C; Murphy, C G; Albrink, M H; McAllister, E W

    1992-06-01

    The leak of ascitic fluid from surgical incisions is thought to be associated with a very high mortality rate. There have been few reports, however, focusing on the clinical characteristics, management, or mortality rates of this condition. During a 10-year period, 18 patients with postoperative ascitic fluid leaks were treated. All patients had ascites before surgery and all had liver disease; in 13 of the 18 patients alcoholic liver disease was the cause of ascites. Ten of the 18 patients died (56%). Midline incisions were more often associated with recalcitrant leaks and fatal complications than were transverse incisions. Early consideration of fascial dehiscence and prompt repair is emphasized. The most effective predictor of survival was cessation of the leak.

  1. 40 CFR 63.1086 - How must I monitor for leaks to cooling water?

    Science.gov (United States)

    2010-07-01

    ... monitor for leaks to cooling water? You must monitor for leaks to cooling water by monitoring each heat... system so that the cooling water flow rate is 51,031 liters per minute or less so that a leak of 3.06 kg... detected a leak. (b) Individual heat exchangers. Monitor the cooling water at the entrance and exit of each...

  2. The Protein Cost of Metabolic Fluxes: Prediction from Enzymatic Rate Laws and Cost Minimization.

    Directory of Open Access Journals (Sweden)

    Elad Noor

    2016-11-01

    Full Text Available Bacterial growth depends crucially on metabolic fluxes, which are limited by the cell's capacity to maintain metabolic enzymes. The necessary enzyme amount per unit flux is a major determinant of metabolic strategies both in evolution and bioengineering. It depends on enzyme parameters (such as kcat and KM constants, but also on metabolite concentrations. Moreover, similar amounts of different enzymes might incur different costs for the cell, depending on enzyme-specific properties such as protein size and half-life. Here, we developed enzyme cost minimization (ECM, a scalable method for computing enzyme amounts that support a given metabolic flux at a minimal protein cost. The complex interplay of enzyme and metabolite concentrations, e.g. through thermodynamic driving forces and enzyme saturation, would make it hard to solve this optimization problem directly. By treating enzyme cost as a function of metabolite levels, we formulated ECM as a numerically tractable, convex optimization problem. Its tiered approach allows for building models at different levels of detail, depending on the amount of available data. Validating our method with measured metabolite and protein levels in E. coli central metabolism, we found typical prediction fold errors of 4.1 and 2.6, respectively, for the two kinds of data. This result from the cost-optimized metabolic state is significantly better than randomly sampled metabolite profiles, supporting the hypothesis that enzyme cost is important for the fitness of E. coli. ECM can be used to predict enzyme levels and protein cost in natural and engineered pathways, and could be a valuable computational tool to assist metabolic engineering projects. Furthermore, it establishes a direct connection between protein cost and thermodynamics, and provides a physically plausible and computationally tractable way to include enzyme kinetics into constraint-based metabolic models, where kinetics have usually been ignored or

  3. Analysis of small leaks

    International Nuclear Information System (INIS)

    Frisch, W.; Hofmann, K.

    1979-01-01

    Problems associated with 'small leaks' are described and requirements are derived for experimental facilities and computer codes. Based on these requirements, a valuation of the existing experimental facilities and codes is presented. Facilities for integral tests in relatively large scale (ex. LOFT) are suitable for small leak test in principle, however minor changes (instrumentation, secondary side) are necessary for the evaluation of certain phenomena. The 'advanced blowdown codes' are capable of describing most of the phenomena occurring during small leak events, however a substantial amount of code development and verification is still needed. In addition, the use of transient codes in small leak analysis is demonstrated. There are some areas (neutronics feedback, influence of control system) in which the use of transient codes is possible and advantageous. (orig.) 891 HP/orig. 892 BRE [de

  4. Fuel leak testing performance at NPP Jaslovske Bohunice

    International Nuclear Information System (INIS)

    Slugen, V.; Krnac, S.; Smiesko, I.

    1995-01-01

    The NPP Bohunice VVER-440 fuel leak testing experience are relatively extensive in comparison with other VVER-440 users. As the first Europe NPP was adapted Siemens (KWU) in core-sipping equipment to VVER-440 units and since this time were have done these tests also for NPP Paks (Hungary) and NPP Dukovany (Czech Republic). The occurrence of leaking fuel assemblies in NPP is in the last 5 years relatively stabilised and low. A significant difference can be observed between type V-230 (31 leaks) and type V-213 (1 leak). None of of the indicated leaking fuel assemblies has been investigated in the hot cell. Therefore cannot be confirm the effective causes of leak occurrence. Nevertheless, the fuel failure rate and the performance of leak testing in NPP Bohunice are comparable to the world standard at PWR's. 1 tab., 2 figs., 3 refs

  5. Fuel leak testing performance at NPP Jaslovske Bohunice

    Energy Technology Data Exchange (ETDEWEB)

    Slugen, V; Krnac, S [Slovak Technical Univ., Bratislava (Slovakia); Smiesko, I [Nuclear Powr Plant EBO, Jaslovske Bohuce (Slovakia)

    1996-12-31

    The NPP Bohunice VVER-440 fuel leak testing experience are relatively extensive in comparison with other VVER-440 users. As the first Europe NPP was adapted Siemens (KWU) in core-sipping equipment to VVER-440 units and since this time were have done these tests also for NPP Paks (Hungary) and NPP Dukovany (Czech Republic). The occurrence of leaking fuel assemblies in NPP is in the last 5 years relatively stabilised and low. A significant difference can be observed between type V-230 (31 leaks) and type V-213 (1 leak). None of of the indicated leaking fuel assemblies has been investigated in the hot cell. Therefore cannot be confirm the effective causes of leak occurrence. Nevertheless, the fuel failure rate and the performance of leak testing in NPP Bohunice are comparable to the world standard at PWR`s. 1 tab., 2 figs., 3 refs.

  6. Stimulated leaks found with SmartBall tool

    Energy Technology Data Exchange (ETDEWEB)

    Anon.

    2011-05-15

    Pure Technologies has developed a SmartBall leak detection tool which can be used in oil and gas pipelines. This tool contains acoustic sensors which listen for leaks and other problems in pipelines. Pig tracking units are used to track the tool along with receivers positioned on the pipe. With these technologies, SmartBall is able to detect small leaks that conventional methods would not detect and to assess their location accurately. Two runs on a Petrobras pipeline in Brazil highlighted the effectiveness of this technology, detecting three simulated leaks as small as 240mL/min. In addition, this system can give an estimation of the leak rate and traverse non piggable pipelines. Software is then used to analyze data and generate a report giving the size and location of the leaks identified. SmartBall is a technology capable of detecting small leaks and locating them in all sorts of oil and gas pipelines.

  7. Optimizing aeration rates for minimizing membrane fouling and its effect on sludge characteristics in a moving bed membrane bioreactor

    International Nuclear Information System (INIS)

    Rahimi, Yousef; Torabian, Ali; Mehrdadi, Naser; Habibi-Rezaie, Mehran; Pezeshk, Hamid; Nabi-Bidhendi, Gholam-Reza

    2011-01-01

    Research highlights: → There is an optimum aeration rate in the MBMBR process compartments. → Optimum aeration rate maximizes nutrients removal. → Optimum aeration rate minimizes membrane fouling. → Both aeration rates in MBBR and membrane compartment can affect on membrane permeability. - Abstract: In MBR processes, sufficient aeration is necessary to maintain sustainable flux and to retard membrane fouling. Membrane permeability, sludge characteristics, nutrient removal and biomass growth at various air flow rates in the membrane and moving bed biofilm reactor (MBBR) compartments were studied in a pilot plant. The highest nitrogen and phosphorous removal rates were found at MBBR aeration rates of 151 and 85 L h -1 and a specific aeration demand per membrane area (SAD m ) of 1.2 and 0.4m air 3 m -2 h -1 , respectively. A linear correlation was found between the amount of attached biofilm and the nutrient removal rate. The aeration rate in the MBBR compartment and SAD m significantly influenced the sludge characteristics and membrane permeability. The optimum combination of the aeration rate in the MBBR compartment and SAD m were 151 L h -1 and 0.8-1.2m air 3 m membrane -2 h -1 , respectively.

  8. Optimizing aeration rates for minimizing membrane fouling and its effect on sludge characteristics in a moving bed membrane bioreactor

    Energy Technology Data Exchange (ETDEWEB)

    Rahimi, Yousef, E-mail: yrahimi@ut.ac.ir [Department of Civil and Environmental Engineering, Graduate Faculty of Environment, University of Tehran, No. 25 Qods St., Enghelab Ave., Tehran (Iran, Islamic Republic of); Torabian, Ali, E-mail: atorabi@ut.ac.ir [Department of Civil and Environmental Engineering, Graduate Faculty of Environment, University of Tehran, No. 25 Qods St., Enghelab Ave., Tehran (Iran, Islamic Republic of); Mehrdadi, Naser, E-mail: mehrdadi@ut.ac.ir [Department of Civil and Environmental Engineering, Graduate Faculty of Environment, University of Tehran, No. 25 Qods St., Enghelab Ave., Tehran (Iran, Islamic Republic of); Habibi-Rezaie, Mehran, E-mail: mhabibi@khayam.ut.ac.ir [Department of Biotechnology, Faculty of Biology, College of Science, University of Tehran, No. 25 Qods St., Enghelab Ave., Tehran (Iran, Islamic Republic of); Pezeshk, Hamid, E-mail: pezeshk@khayam.ut.ac.ir [Department of Statistics, Faculty of Mathematics and Computer, College of Science, University of Tehran, No. 25 Qods St., Enghelab Ave., Tehran (Iran, Islamic Republic of); Nabi-Bidhendi, Gholam-Reza, E-mail: ghhendi@ut.ac.ir [Department of Civil and Environmental Engineering, Graduate Faculty of Environment, University of Tehran, No. 25 Qods St., Enghelab Ave., Tehran (Iran, Islamic Republic of)

    2011-02-28

    Research highlights: {yields} There is an optimum aeration rate in the MBMBR process compartments. {yields} Optimum aeration rate maximizes nutrients removal. {yields} Optimum aeration rate minimizes membrane fouling. {yields} Both aeration rates in MBBR and membrane compartment can affect on membrane permeability. - Abstract: In MBR processes, sufficient aeration is necessary to maintain sustainable flux and to retard membrane fouling. Membrane permeability, sludge characteristics, nutrient removal and biomass growth at various air flow rates in the membrane and moving bed biofilm reactor (MBBR) compartments were studied in a pilot plant. The highest nitrogen and phosphorous removal rates were found at MBBR aeration rates of 151 and 85 L h{sup -1} and a specific aeration demand per membrane area (SAD{sub m}) of 1.2 and 0.4m{sub air}{sup 3} m{sup -2} h{sup -1}, respectively. A linear correlation was found between the amount of attached biofilm and the nutrient removal rate. The aeration rate in the MBBR compartment and SAD{sub m} significantly influenced the sludge characteristics and membrane permeability. The optimum combination of the aeration rate in the MBBR compartment and SAD{sub m} were 151 L h{sup -1} and 0.8-1.2m{sub air}{sup 3}m{sub membrane}{sup -2} h{sup -1}, respectively.

  9. An ICSI rate of 90% minimizes complete failed fertilization and provides satisfactory implantation rates without elevating fetal abnormalities.

    Science.gov (United States)

    Yovich, John L; Conceicao, Jason L; Marjanovich, Nicole; Ye, Yun; Hinchliffe, Peter M; Dhaliwal, Satvinder S; Keane, Kevin N

    2018-05-22

    IVF cycles utilizing the ICSI technique for fertilization have been rising over the 25 years since its introduction, with indications now extending beyond male factor infertility. We have performed ICSI for 87% of cases compared with the ANZARD average of 67%. This retrospective study reports on the outcomes of 1547 autologous ART treatments undertaken over a recent 3-year period. Based on various indications, cases were managed within 3 groupings - IVF Only, ICSI Only or IVF-ICSI Split insemination where oocytes were randomly allocated. Overall 567 pregnancies arose from mostly single embryo transfer procedures up to December 2016, with 402 live births, comprising 415 infants and a low fetal abnormality rate (1.9%) was recorded. When the data was adjusted for confounders such as maternal age, measures of ovarian reserve and sperm quality, it appeared that IVF-generated and ICSI-generated embryos had a similar chance of both pregnancy and live birth. In the IVF-ICSI Split model, significantly more ICSI-generated embryos were utilised (2.5 vs 1.8; p < 0.003) with productivity rates of 67.8% for pregnancy and 43.4% for livebirths per OPU for this group. We conclude that ART clinics should apply the insemination method which will maximize embryo numbers and the first treatment for unexplained infertility should be undertaken within the IVF-ICSI Split model. Whilst ICSI-generated pregnancies are reported to have a higher rate of fetal abnormalities, our data is consistent with the view that the finding is not due to the ICSI technique per se. Copyright © 2018 Society for Biology of Reproduction & the Institute of Animal Reproduction and Food Research of Polish Academy of Sciences in Olsztyn. Published by Elsevier B.V. All rights reserved.

  10. Effects of minimal processing on the respiration rate and quality of rambutan cv. ‘Rong-Rien’

    Directory of Open Access Journals (Sweden)

    Buncha Ooraikul

    2008-04-01

    Full Text Available Respiration rate at 4oC and minimal processing of rambutan cv. ‘Rong-Rien’ were investigated. Rambutan was harvested from Amphur Ban Na San, Surat Thani Province, at the stage when its skin was turning into a combination of red, green and yellow. After harvesting, the fruits were size-graded to 27-30 fruits/kg, hydrocooled to 14oC, packed with ice in Styrofoam boxes and transported to the laboratory at Prince of Songkla University within 6 h. The respiration rate of fresh rambutan fruits was monitored. For minimal processing, the fruits were soaked in warm solution (55oC of 100 ppm sodium hypochlorite for one min and immediately cooled in cold water until their internal temperature reached 14oC. The minimal process included peeling, with and without coring. The peeled and peeled and cored rambutan samples were immersed in a solution of 0.5% citric acid + 0.5% CaCl2 at 4oC for 2 min. The average respiration rates (within 6 h at 4oC of whole fruit, peeled, and peeled and cored rambutan samples were measured and found to be 122, 134 and 143 mg CO2/kg/h, respectively. These findings indicated that a preparation style as peeled rambutan without coring, nylon/LLDPE bag, storage temperature of 4.0±1oC, were suitably applied for processed rambutans. To obtain a longer extended shelf life (>12 days of minimally processed peeled rambutans, further study on food additives, including acidulants and preservative used and gas composition in modified atmosphere packaging (MAP is needed.

  11. WRSS jumper leak assessment

    International Nuclear Information System (INIS)

    BAILEY, J.W.

    1999-01-01

    The purpose of this assessment is: (1) to assemble and document the facts associated with three recently installed jumpers which have leaked either during actual process operation or during post installation testing; (2) to describe the corrective actions taken and to identify any process improvements which need to be implemented in the Hanford jumper design and installation activities; and (3) to document WRSS jumper leak lessons learned for use by future projects and other jumper design, fabrication, and installation activities

  12. Pipeline Leak Detection Techniques

    OpenAIRE

    Chis, Timur

    2009-01-01

    Leak detection systems range from simple, visual line walking and checking ones to complex arrangements of hard-ware and software. No one method is universally applicable and operating requirements dictate which method is the most cost effective. The aim of the paper is to review the basic techniques of leak detection that are currently in use. The advantages and disadvantages of each method are discussed and some indications of applicability are outlined.

  13. Pipeline Leak Detection Techniques

    Directory of Open Access Journals (Sweden)

    Timur Chis, Ph.D., Dipl.Eng.

    2007-01-01

    Full Text Available Leak detection systems range from simple, visual line walking and checking ones to complex arrangements of hard-ware and software. No one method is universally applicable and operating requirements dictate which method is the most cost effective. The aim of the paper is to review the basic techniques of leak detection that are currently in use. The advantages and disadvantages of each method are discussed and some indications of applicability are outlined.

  14. Low Level Leaks

    Science.gov (United States)

    1998-01-01

    NASA has transferred the improved portable leak detector technology to UE Systems, Inc.. This instrument was developed to detect leaks in fluid systems of critical launch and ground support equipment. This system incorporates innovative electronic circuitry, improved transducers, collecting horns, and contact sensors that provide a much higher degree of reliability, sensitivity and versatility over previously used systems. Potential commercial uses are pipelines, underground utilities, air-conditioning systems, petrochemical systems, aerospace, power transmission lines and medical devices.

  15. SINGLE-SHELL TANKS LEAK INTEGRITY ELEMENTS/SX FARM LEAK CAUSES AND LOCATIONS - 12127

    Energy Technology Data Exchange (ETDEWEB)

    VENETZ TJ; WASHENFELDER D; JOHNSON J; GIRARDOT C

    2012-01-25

    leak detection. In-tank parameters can include temperature of the supernatant and sludge, types of waste, and chemical determination by either transfer or sample analysis. Ex-tank information can be assembled from many sources including design media, construction conditions, technical specifications, and other sources. Five conditions may have contributed to SX Farm tank liner failure including: tank design, thermal shock, chemistry-corrosion, liner behavior (bulging), and construction temperature. Tank design did not apparently change from tank to tank for the SX Farm tanks; however, there could be many unknown variables present in the quality of materials and quality of construction. Several significant SX Farm tank design changes occurred from previous successful tank farm designs. Tank construction occurred in winter under cold conditions which could have affected the ductile to brittle transition temperature of the tanks. The SX Farm tanks received high temperature boiling waste from REDOX which challenged the tank design with rapid heat up and high temperatures. All eight of the leaking SX Farm tanks had relatively high rate of temperature rise. Supernatant removal with subsequent nitrate leaching was conducted in all but three of the eight leaking tanks prior to leaks being detected. It is possible that no one characteristic of the SX Farm tanks could in isolation from the others have resulted in failure. However, the application of so many stressors - heat up rate, high temperature, loss of corrosion protection, and tank design - working jointly or serially resulted in their failure. Thermal shock coupled with the tank design, construction conditions, and nitrate leaching seem to be the overriding factors that can lead to tank liner failure. The distinction between leaking and sound SX Farm tanks seems to center on the waste types, thermal conditions, and nitrate leaching.

  16. Single-Shell Tanks Leak Integrity Elements/ SX Farm Leak Causes and Locations - 12127

    Energy Technology Data Exchange (ETDEWEB)

    Girardot, Crystal [URS- Safety Management Solutions, Richland, Washington 99352 (United States); Harlow, Don [ELR Consulting Richland, Washington 99352 (United States); Venetz, Theodore; Washenfelder, Dennis [Washington River Protection Solutions, LLC Richland, Washington 99352 (United States); Johnson, Jeremy [U.S. Department of Energy, Office of River Protection Richland, Washington 99352 (United States)

    2012-07-01

    leak detection. In-tank parameters can include temperature of the supernatant and sludge, types of waste, and chemical determination by either transfer or sample analysis. Ex-tank information can be assembled from many sources including design media, construction conditions, technical specifications, and other sources. Five conditions may have contributed to SX Farm tank liner failure including: tank design, thermal shock, chemistry-corrosion, liner behavior (bulging), and construction temperature. Tank design did not apparently change from tank to tank for the SX Farm tanks; however, there could be many unknown variables present in the quality of materials and quality of construction. Several significant SX Farm tank design changes occurred from previous successful tank farm designs. Tank construction occurred in winter under cold conditions which could have affected the ductile to brittle transition temperature of the tanks. The SX Farm tanks received high temperature boiling waste from REDOX which challenged the tank design with rapid heat up and high temperatures. All eight of the leaking SX Farm tanks had relatively high rate of temperature rise. Supernatant removal with subsequent nitrate leaching was conducted in all but three of the eight leaking tanks prior to leaks being detected. It is possible that no one characteristic of the SX Farm tanks could in isolation from the others have resulted in failure. However, the application of so many stressors - heat up rate, high temperature, loss of corrosion protection, and tank design working jointly or serially resulted in their failure. Thermal shock coupled with the tank design, construction conditions, and nitrate leaching seem to be the overriding factors that can lead to tank liner failure. The distinction between leaking and sound SX Farm tanks seems to center on the waste types, thermal conditions, and nitrate leaching. (authors)

  17. Detection of steam generator tube leaks in pressurized water reactors

    International Nuclear Information System (INIS)

    Roach, W.H.

    1984-11-01

    This report addresses the early detection of small steam generator tube leaks in pressurized water reactors. It identifies physical parameters, establishes instrumentation performance goals, and specifies sensor types and locations. It presents a simple algorithm that yields the leak rate as a function of known or measurable quantities. Leak rates of less than one-tenth gram per second should be detectable with existing instrumentation

  18. Helium leak testing the Westinghouse LCP coil

    International Nuclear Information System (INIS)

    Merritt, P.A.; Attaar, M.H.; Hordubay, T.D.

    1983-01-01

    The tests, equipment, and techniques used to check the Westinghouse LCP coil for coolant flow path integrity and helium leakage are unique in terms of test sensitivity and application. This paper will discuss the various types of helium leak testing done on the LCP coil as it enters different stages of manufacture. The emphasis will be on the degree of test sensitivity achieved under shop conditions, and what equipment, techniques and tooling are required to achieve this sensitivity (5.9 x 10 -8 scc/sec). Other topics that will be discussed are helium flow and pressure drop testing which is used to detect any restrictions in the flow paths, and the LCP final acceptance test which is the final leak test performed on the coil prior to its being sent for testing. The overall allowable leak rate for this coil is 5 x 10 -6 scc/sec. A general evaluation of helium leak testing experience are included

  19. Study on the Fluid Leak Diagnosis for Steam Valve in Power Plant

    International Nuclear Information System (INIS)

    Lee, Sang-Guk; Park, Jong-Hyuck; Yoo, Keun-Bae; Lee, Sun-Ki; Hong, Sung-Yull

    2006-01-01

    This study aims to estimate the applicability of acoustic emission(AE) method for the internal fluid leak from the valves. In this study, 4 inch gate steam valve leak tests were performed in order to analyze AE properties when leaks arise in valve seat. As a result of leak test for valve seat in a secondary system of power plant, we conformed that leak sound level increased in proportion to the increase of leak rate, and leak rates were compared to simulated tests. The resulting plots of leak rate versus peak frequency and AE signal level were the primary basis for determining the feasibility of quantifying leak acoustically. Previously, the large amount of data attained also allowed a favorable investigation of the effects of different leak paths, leak rates, pressure differentials through simulated test. All results of application tests are compared with results of simulated test. From the application tests, it was suggested that the AE method for diagnosis of steam leak was applicable. This paper presents quantitative measurements of fluid valve leak conditions by the analysis of AE parameter, FFT(fast fourier transform) and RMS(root mean square) level. Test apparatus were fabricated to accept a variety of leaking steam valves in order to determine what characteristics of AE signal change with leak conditions. The data for each valve were generated by varying the leak rate and recording the averaged RMS level versus time and frequency versus amplitude(FFT). Leak rates were varied by the valve differential pressure and valve size and leaking valves were observed in service. Most of the data analysis involved plotting the leak rate versus RMS level at a specific frequency to determine how well the two variables correlate in terms of accuracy, resolution, and repeatability

  20. A Cost-Based Adaptive Handover Hysteresis Scheme to Minimize the Handover Failure Rate in 3GPP LTE System

    Directory of Open Access Journals (Sweden)

    Gil Gye-Tae

    2010-01-01

    Full Text Available We deal with a cost-based adaptive handover hysteresis scheme for the horizontal handover decision strategies, as one of the self-optimization techniques that can minimize the handover failure rate (HFR in the 3rd generation partnership project (3GPP long-term evolution (LTE system based on the network-controlled hard handover. Especially, for real-time operation, we propose an adaptive hysteresis scheme with a simplified cost function considering some dominant factors closely related to HFR performance such as the load difference between the target and serving cells, the velocity of user equipment (UE, and the service type. With the proposed scheme, a proper hysteresis value based on the dominant factors is easily obtained, so that the handover parameter optimization for minimizing the HFR can be effectively achieved. Simulation results show that the proposed scheme can support better HFR performance than the conventional schemes.

  1. Detection of primary coolant leaks in NPP

    International Nuclear Information System (INIS)

    Slavov, S.; Bakalov, I.; Vassilev, H.

    2001-01-01

    The thermo-hydraulic analyses of the SG box behaviour of Kozloduy NPP units 3 and 4 in case of small primary circuit leaks and during normal operation of the existing ventilation systems in order to determine the detectable leakages from the primary circuit by analysing different parameters used for the purposes of 'Leak before break' concept, performed by ENPRO Consult Ltd. are presented. The following methods for leak detection: measurement of relative air humidity in SG box (can be used for detection of leaks with flow rate 3.78 l/min within one hour at ambient parameters - temperature 40 0 - 60 0 C and relative humidity form 30% to 60%); measurement of water level in SG box sumps (can not be used for reliable detection of small primary circuit leakages with flow rate about 3.78 l/min); measurement of gaseous radioactivity in SG box( can be used as a general global indication for detection of small leakages from the primary circuit); measurement of condensate flow after the air coolers of P-1 venting system (can be used for primary circuit leak detection) are considered. For determination of the confinement behaviour, a model used with computer code MELCOR has been developed by ENPRO Consult Ltd. A brief summary based on the capabilities of the different methods of leak detection, from the point of view of the applicability of a particular method is given. For both Units 3 and 4 of Kozloduy NPP a qualified complex system for small leak detection is planned to be constructed. Such a system has to unite the following systems: acoustic system for leak detection 'ALUS'; system for control of the tightness of the main primary circuit pipelines by monitoring the local humidity; system for primary circuit leakage detection by measuring condensate run-off in collecting tank after ventilation system P-1 air coolers

  2. Limiting enclosures. Method of control of the leak rate per hour. Enclosures of classes 1 and 2. Method of measurement of the increase of the oxygen titre in volume

    International Nuclear Information System (INIS)

    1984-07-01

    The present standard can be applied to limiting enclosures working under depression or overpressure. It can be applied to limiting enclosures used for works on radioactive or toxic materials. The leak rate per hour is -2 h -1 . The measuring method uses oxygen determination after the enclusore is filled with an inert gas. The influence of pressure and temperature are analysed. The measurement installation and its operating way are presented; the accuracy of the method given. This standard supersedes the experimental standard of December 1982 [fr

  3. Assessment of historical leak model methodology as applied to the REDOX high-level waste tank SX-108

    International Nuclear Information System (INIS)

    JONES, T.E.

    1999-01-01

    Using the Historical Leak Model approach, the estimated leak rate (and therefore, projected leak volume) for Tank 241-SX-108 could not be reproduced using the data included in the initial document describing the leak methodology. An analysis of parameters impacting tank heat load calculations strongly suggest that the historical tank operating data lack the precision and accuracy required to estimate tank leak volumes using the Historical Leak Model methodology

  4. Power Minimization of a Wireless Sensor Node under Different Rate Constraints

    KAUST Repository

    Solares, Jose

    2016-03-31

    Future wireless networks are expected to handle a huge number of devices, including sensors, within a low energy consumption. In this scope, we present, in this paper, performance of wireless sensor networks (WSN). Specifically, we aim at finding the optimal transmit power of a node communicating with multiple receivers in a cognitive radio (CR) spectrum sharing framework, i.e., existence of an active primary user. We first present the optimal power with single secondary receiver, under instantaneous or average transmission rate constraints. Then, we propose a suboptimal solution for an easier, yet efficient, implementation and perform insightful asymptotical analysis for both schemes with Rayleigh fading. Afterwards, we extend our results to a multiple secondary receives CR scenario and present the corresponding optimal and suboptimal transmit power while satisfying independent peak/average and sum of peak/average transmission rate constraints. The corresponding numerical results are provided for Rayleigh and Nakagami-m fading channels. We characterize some transmission outage events depending on system parameters.

  5. Power Minimization of a Wireless Sensor Node under Different Rate Constraints

    KAUST Repository

    Solares, Jose; Sboui, Lokman; Rezki, Zouheir; Alouini, Mohamed-Slim

    2016-01-01

    Future wireless networks are expected to handle a huge number of devices, including sensors, within a low energy consumption. In this scope, we present, in this paper, performance of wireless sensor networks (WSN). Specifically, we aim at finding the optimal transmit power of a node communicating with multiple receivers in a cognitive radio (CR) spectrum sharing framework, i.e., existence of an active primary user. We first present the optimal power with single secondary receiver, under instantaneous or average transmission rate constraints. Then, we propose a suboptimal solution for an easier, yet efficient, implementation and perform insightful asymptotical analysis for both schemes with Rayleigh fading. Afterwards, we extend our results to a multiple secondary receives CR scenario and present the corresponding optimal and suboptimal transmit power while satisfying independent peak/average and sum of peak/average transmission rate constraints. The corresponding numerical results are provided for Rayleigh and Nakagami-m fading channels. We characterize some transmission outage events depending on system parameters.

  6. Ammonia Leak Locator Study

    Science.gov (United States)

    Dodge, Franklin T.; Wuest, Martin P.; Deffenbaugh, Danny M.

    1995-01-01

    The thermal control system of International Space Station Alpha will use liquid ammonia as the heat exchange fluid. It is expected that small leaks (of the order perhaps of one pound of ammonia per day) may develop in the lines transporting the ammonia to the various facilities as well as in the heat exchange equipment. Such leaks must be detected and located before the supply of ammonia becomes critically low. For that reason, NASA-JSC has a program underway to evaluate instruments that can detect and locate ultra-small concentrations of ammonia in a high vacuum environment. To be useful, the instrument must be portable and small enough that an astronaut can easily handle it during extravehicular activity. An additional complication in the design of the instrument is that the environment immediately surrounding ISSA will contain small concentrations of many other gases from venting of onboard experiments as well as from other kinds of leaks. These other vapors include water, cabin air, CO2, CO, argon, N2, and ethylene glycol. Altogether, this local environment might have a pressure of the order of 10(exp -7) to 10(exp -6) torr. Southwest Research Institute (SwRI) was contracted by NASA-JSC to provide support to NASA-JSC and its prime contractors in evaluating ammonia-location instruments and to make a preliminary trade study of the advantages and limitations of potential instruments. The present effort builds upon an earlier SwRI study to evaluate ammonia leak detection instruments [Jolly and Deffenbaugh]. The objectives of the present effort include: (1) Estimate the characteristics of representative ammonia leaks; (2) Evaluate the baseline instrument in the light of the estimated ammonia leak characteristics; (3) Propose alternative instrument concepts; and (4) Conduct a trade study of the proposed alternative concepts and recommend promising instruments. The baseline leak-location instrument selected by NASA-JSC was an ion gauge.

  7. Energy minimization of mobile video devices with a hardware H.264/AVC encoder based on energy-rate-distortion optimization

    Science.gov (United States)

    Kang, Donghun; Lee, Jungeon; Jung, Jongpil; Lee, Chul-Hee; Kyung, Chong-Min

    2014-09-01

    In mobile video systems powered by battery, reducing the encoder's compression energy consumption is critical to prolong its lifetime. Previous Energy-rate-distortion (E-R-D) optimization methods based on a software codec is not suitable for practical mobile camera systems because the energy consumption is too large and encoding rate is too low. In this paper, we propose an E-R-D model for the hardware codec based on the gate-level simulation framework to measure the switching activity and the energy consumption. From the proposed E-R-D model, an energy minimizing algorithm for mobile video camera sensor have been developed with the GOP (Group of Pictures) size and QP(Quantization Parameter) as run-time control variables. Our experimental results show that the proposed algorithm provides up to 31.76% of energy consumption saving while satisfying the rate and distortion constraints.

  8. Environmental risk comparisons with internal methods of UST leak detection

    International Nuclear Information System (INIS)

    Durgin, P.B.

    1993-01-01

    The past five years have seen a variety of advances in how leaks can be detected from within underground storage tanks. Any leak-detection approach employed within a storage tanks must be conducted at specific time intervals and meet certain leak-rate criteria according to federal and state regulations. Nevertheless, the potential environmental consequences of leak detection approaches differ widely. Internal, volumetric UST monitoring techniques have developed over time including: (1) inventory control with stick measurements, (2) precision tank testing, (3) automatic tank gauging (ATG), (4) statistical inventory reconciliation (SIR), and (5) statistical techniques with automatic tank gauging. An ATG focuses on the advantage of precise data but measured for only a brief period. On the other hand, stick data has less precision but when combined with SIR over extended periods it too can detect low leak rates. Graphs demonstrate the comparable amounts of fuel than can leak out of a tank before being detected by these techniques. The results indicate that annual tank testing has the greatest potential for large volumes of fuel leaking without detection while new statistical approaches with an ATG have the least potential. The environmental implications of the volumes of fuel leaked prior to detection are site specific. For example, if storage tank is surrounded by a high water table and in a sole-source aquifer even small leaks may cause problems. The user must also consider regulatory risks. The level of environmental and regulatory risk should influence selection of the UST leak detection method

  9. Fabrication of ultra-sensitive leak detection standards

    International Nuclear Information System (INIS)

    Winkelman, C.R.

    1980-01-01

    The primary difficulty with flow rate measurements below 10 -10 standard cubic centimeters per second (std. cc/sec) is that there are no commercially available standards. The requirements, however, dictate that the problem of design and construction of a qualifiable standard in the ultra-sensitive range had to be solved. There are a number of leak types which were considered - capillary leaks, orifice leaks, and the pore type leaks, among others. The capillary leak was not used because of the cracking or sorting effects that are common to this type leak. For example, a gas blend flowing through a capillary leak will result in the lighter gases passing through the leak first. The difficulty of fabricating the proper hole size in relation to the flow rate requirements ruled out the orifice type leak. The choice was the pore type leak which utilizes the basic concept of a stainless steel knife edge driven into a fixed section composed of stainless steel with a gold over-lay and maintained under force

  10. Leak testing using helium leak detector

    International Nuclear Information System (INIS)

    Aparicio, G.; Mathot, S.; Munoz, C.; Orlando, O.

    1997-01-01

    Most of the equipment used in the industry and particularly in the nuclear activity need to be, vacuum or pressure tight, for operative and safety requirements. These devices have to satisfy particular regulations in order to be qualified by means of operating licences. One of the most efficient system to ensure leaktightnes is using a helium leak detector with a mass spectrometer. In this paper we show the equipment and the devices employed in fuel rods fabrication for CAREM project, and some typical material defects. Operating system and the sensitivity of this method is also described. (author) [es

  11. Engineering study of tank leaks related to hydraulic retrieval of sludge from tank 241-C-106

    International Nuclear Information System (INIS)

    Lowe, S.S.; Carlos, W.C.; Irwin, J.J.; Khaleel, R.; Kline, N.W.; Ludowise, J.D.; Marusich, R.M.; Rittman, P.D.

    1993-01-01

    This study evaluates hydraulic retrieval (sluicing) of the waste in single-shell tank 241-C-106 with respect to the likelihood of tank leaks, gross volumes of potential leaks, and their consequences. A description of hydraulic retrieval is developed to establish a baseline for the study. Leak models are developed based on postulated leak mechanisms to estimate the amount of waste that could potentially leak while sluicing. Transport models describe the movement of the waste constituents in the surrounding soil and groundwater after a leak occurs. Environmental impact and risk associated with tank leaks are evaluated. Transport of leaked material to the groundwater is found to be dependent on the rate of recharge of moisture in the soil for moderate-sized leaks. Providing a cover over the tank and surrounding area would eliminate the recharge. The bulk of any leaked material would remain in the vicinity of the tank for remedial action

  12. Evaluation of pipeline leak detection systems

    International Nuclear Information System (INIS)

    Glauz, W.D.; Flora, J.D.; Hennon, G.J.

    1993-01-01

    Leaking underground storage tank system presents an environmental concern and a potential health hazard. It is well known that leaks in the piping associated with these systems account for a sizeable fraction of the leaks. EPA has established performance standards for pipeline leak detection systems, and published a document presenting test protocols for evaluating these systems against the standards. This paper discusses a number of facets and important features of evaluating such systems, and presents results from tests of several systems. The importance of temperature differences between the ground and the product in the line is shown both in theory and with test data. The impact of the amount of soil moisture present is addressed, along with the effect of frozen soil. These features are addressed both for line tightness test systems, which must detect leaks of 0.10 gal/h (0.38 L/h) at 150% of normal line pressure, or 0.20 gal/h (0.76 L/h) at normal line pressure, and for automatic line leak detectors that must detect leaks of 3 gal/h (11 L/h) at 10 psi (69 kPa) within an hour of the occurrence of the leak. This paper also addresses some statistical aspects of the evaluation of these systems. Reasons for keeping the evaluation process ''blind'' to the evaluated company are given, along with methods for assuring that the tests are blind. Most importantly, a test procedure is presented for evaluating systems that report a flow rate (not just a pass/fail decision) that is much more efficient than the procedure presented in the EPA protocol, and is just as stringent

  13. Evaluation of advanced and current leak detection systems

    International Nuclear Information System (INIS)

    Kupperman, D.S.

    1988-01-01

    U.S. Nuclear Regulatory Commission Guide 1.45 recommends the use of at least three different detection methods in reactors to detect leakage. Monitoring of both sump-flow and airborne particulate radioactivity is mandatory. A third method can involve either monitoring of condensate flow rate from air coolers or monitoring of airborne gaseous radioactivity. Although the methods currently used for leak detection reflect the state of the art, other techniques may be developed and used. Since the recommendations of Regulatory Guide 1.45 are not mandatory, Licensee Event Report Compilations have been reviewed to help establish actual capabilities for leak detection. The review of event reports, which had previously covered the period of June 1985 to August 1986 has been extended, and now covers events to June 1987. The total number of significant events is now 83. These reports have provided documented, sometimes detailed, summaries of reactor leaks. They have helped establish the capabilities of existing systems to detect and locate leaks. Differences between PWRs and BWRs with regard to leak detection have now been analyzed. With regard to detection methods, the greatest differences between reactor types are as follows: (a) The sump pump is reported as the detection method more frequently in BWRs than in PWRs (64% vs. 35%). (b) The radiation monitor is reported as the detection method (excluding false alarms) more frequently in PWRs. Current efforts at Argonne National Laboratory (ANL) to evaluate advanced acoustic leak detection methods are directed toward the generation and analysis of acoustic data from large (0.5 to 10 gal/min) leaks and modification of the software of the GARD/ANL advanced acoustic leak detection system. In order to reach the goal of 10 gal/min leaks, the Steam Generator Test Facility at ANL has been modified to carry out the leak testing. Tests were carried out with water at 525 deg. F and 1100 psi leaking through a fatigue crack in a 4-in

  14. The experiment and analysis on small leak phenomena

    International Nuclear Information System (INIS)

    Jeong, Kyung Chai; Hwang, S. T.; Kim, B. H.; Jeong, J. Y.

    2000-07-01

    The liquid sodium which is used as a coolant in LMFBR, may give rise to a serious trouble in the safety aspect of steam generator. The defects in a heat transfer tube, such as pin-hole or tube welding defect, will result in a leakage of high pressure steam into the sodium side and production of hydrogen gas and corrosive sodium compounds which can cause significant damage to the tube wall of steam generator by using exothermic reaction. In significant damage to the tube wall of steam generator by using exothermic reaction. In this case, initial leak size will be enlarged with time and the leak rate developed to large leak through the micro, small, intermediate leaks. Therefore, the analysis of sodium-water reaction phenomena on the micro and small water leaks in the heat transfer tube is very important in the initial leak stage in the aspects of the protection of leak progress and safety evaluation of steam generator. In this study, firstly, the micro and small leaks phenomena, such as reopen size, shape, and time of leak path, self-wastage, corrosion of tube materials, was analyzed from the literature survey and water leakage experiments using the leak specimen. In small water leak experiments, the leak path was plugged by the sodium-water reaction products at the leak path of a specimen, and re-open phenomena were not observed in initial experiments. Other leak experiments, reopen phenomena of self-plugged leak path was observed. Re-open mechanism of sealed path could be explained by the thermal transient and vibration of heat transfer tube. As a result, perfect reopen time of self plugged leak path was observed to be about 130 minutes after water leak initiation. Reopen shape of a specimen was appeared with double layer of circular type, and reopen size of this specimen surface was about 2 mm diameter on sodium side. Also, the corrosion of a specimen initiated from sodium side, the segregation phenomena of Cr in the specimen was found much more than those of

  15. Remote leak localization approach for fusion machines

    International Nuclear Information System (INIS)

    Durocher, Au.; Bruno, V.; Chantant, M.; Gargiulo, L.; Gherman, T.; Hatchressian, J.-C.; Houry, M.; Le, R.; Mouyon, D.

    2013-01-01

    Highlights: ► Description of leaks issue. ► Selection of leak localization concepts. ► Qualification of leak localization concepts. -- Abstract: Fusion machine operation requires high-vacuum conditions and does not tolerate water or gas leak in the vacuum vessels, even if they are micrometric. Tore Supra, as a fully actively cooled tokamak, has got a large leak management experience; 34 water leaks occurred since the beginning of its operation in 1988. To handle this issue, after preliminary machine protection phases, the current process for leak localization is based on water or helium pressurization network by network. It generally allows the identification of a set of components where the leakage element is located. However, the unique background of CEA-IRFM laboratory points needs of accuracy and promptness out in the leak localization process. Moreover, in-vessel interventions have to be performed trying to minimize time and risks for the persons. They are linked to access conditions, radioactivity, tracer gas high pressure and vessel conditioning. Remote operation will be one of the ways to improve these points on future fusion machines. In this case, leak sensors would have to be light weight devices in order to be integrated on a carrier or to be located outside with a sniffing process set up. A leak localization program is on-going at CEA-IRFM Laboratory with the first goal of identifying and characterizing relevant concepts to localize helium or water leaks on ITER. In the same time, CEA has developed robotic carrier for effective in-vessel intervention in a hostile environment. Three major tests campaigns with the goal to identify leak sensors have been achieved on several CEA test-beds since 2010. Very promising results have been obtained: relevant scenario of leak localization performed, concepts tested in a high volume test-bed called TITAN, and, in several conditions of pressure and temperature (ultrahigh vacuum to atmospheric pressure and 20

  16. Remote leak localization approach for fusion machines

    Energy Technology Data Exchange (ETDEWEB)

    Durocher, Au., E-mail: aurelien.durocher@cea.fr [CEA-IRFM, F-13108 Saint Paul-Lez-Durance (France); Bruno, V.; Chantant, M.; Gargiulo, L. [CEA-IRFM, F-13108 Saint Paul-Lez-Durance (France); Gherman, T. [Floralis UJF Filiale, F-38610 Gières (France); Hatchressian, J.-C.; Houry, M.; Le, R.; Mouyon, D. [CEA-IRFM, F-13108 Saint Paul-Lez-Durance (France)

    2013-10-15

    Highlights: ► Description of leaks issue. ► Selection of leak localization concepts. ► Qualification of leak localization concepts. -- Abstract: Fusion machine operation requires high-vacuum conditions and does not tolerate water or gas leak in the vacuum vessels, even if they are micrometric. Tore Supra, as a fully actively cooled tokamak, has got a large leak management experience; 34 water leaks occurred since the beginning of its operation in 1988. To handle this issue, after preliminary machine protection phases, the current process for leak localization is based on water or helium pressurization network by network. It generally allows the identification of a set of components where the leakage element is located. However, the unique background of CEA-IRFM laboratory points needs of accuracy and promptness out in the leak localization process. Moreover, in-vessel interventions have to be performed trying to minimize time and risks for the persons. They are linked to access conditions, radioactivity, tracer gas high pressure and vessel conditioning. Remote operation will be one of the ways to improve these points on future fusion machines. In this case, leak sensors would have to be light weight devices in order to be integrated on a carrier or to be located outside with a sniffing process set up. A leak localization program is on-going at CEA-IRFM Laboratory with the first goal of identifying and characterizing relevant concepts to localize helium or water leaks on ITER. In the same time, CEA has developed robotic carrier for effective in-vessel intervention in a hostile environment. Three major tests campaigns with the goal to identify leak sensors have been achieved on several CEA test-beds since 2010. Very promising results have been obtained: relevant scenario of leak localization performed, concepts tested in a high volume test-bed called TITAN, and, in several conditions of pressure and temperature (ultrahigh vacuum to atmospheric pressure and 20

  17. SEALING SIMULATED LEAKS

    Energy Technology Data Exchange (ETDEWEB)

    Michael A. Romano

    2004-09-01

    This report details the testing equipment, procedures and results performed under Task 7.2 Sealing Simulated Leaks. In terms of our ability to seal leaks identified in the technical topical report, Analysis of Current Field Data, we were 100% successful. In regards to maintaining seal integrity after pigging operations we achieved varying degrees of success. Internal Corrosion defects proved to be the most resistant to the effects of pigging while External Corrosion proved to be the least resistant. Overall, with limitations, pressure activated sealant technology would be a viable option under the right circumstances.

  18. Fuel rod leak detector

    International Nuclear Information System (INIS)

    Womack, R.E.

    1978-01-01

    A typical embodiment of the invention detects leaking fuel rods by means of a radiation detector that measures the concentration of xenon-133 ( 133 Xe) within each individual rod. A collimated detector that provides signals related to the energy of incident radiation is aligned with one of the ends of a fuel rod. A statistically significant sample of the gamma radiation (γ-rays) that characterize 133 Xe is accumulated through the detector. The data so accumulated indicates the presence of a concentration of 133 Xe appropriate to a sound fuel rod, or a significantly different concentration that reflects a leaking fuel rod

  19. Pancreatic stump closure using only stapler is associated with high postoperative fistula rate after minimal invasive surgery.

    Science.gov (United States)

    Yüksel, Adem; Bostancı, Erdal Birol; Çolakoğlu, Muhammet Kadri; Ulaş, Murat; Özer, İlter; Karaman, Kerem; Akoğlu, Musa

    2018-03-01

    Postoperative pancreatic fistula (POPF) is the most common cause of morbidity and mortality after distal pancreatectomy (DP). The aim of the present study is to determine the risk factors that can lead to POPF. The study was conducted between January 2008 and December 2012. A total of 96 patients who underwent DP were retrospectively analyzed. Overall, 24 patients (25%) underwent laparoscopic distal pancreatectomy (LDP) and 72 patients (75%) open surgery. The overall morbidity rate was 51% (49/96). POPF (32/96, 33.3%) was the most common postoperative complication. Grade B fistula (18/32, 56.2%) was the most common fistula type according to the International Study Group on Pancreatic Fistula definition. POPF rate was significantly higher in the minimally invasive surgery group (50%, p=0.046). POPF rate was 58.6% (17/29) in patients whose pancreatic stump closure was performed with only stapler, whereas POPF rate was 3.6% (1/28) in the group where the stump was closed with stapler plus oversewing sutures. Both minimally invasive surgery (OR: 0.286, 95% CI: 0.106-0.776, p=0.014) and intraoperative blood transfusion (OR: 4.210, 95% CI: 1.155-15.354, p=0.029) were detected as independent risk factors for POPF in multi-variety analysis. LDP is associated with a higher risk of POPF when stump closure is performed with only staplers. Intraoperative blood transfusion is another risk factor for POPF. On the other hand, oversewing sutures to the stapler line reduces the risk of POPF.

  20. Ventricular fibrillation occurring after atrioventricular node ablation despite minimal difference between pre- and post-ablation heart rates.

    Science.gov (United States)

    Squara, F; Theodore, G; Scarlatti, D; Ferrari, E

    2017-02-01

    We report the case of an 82-year-old man presenting with ventricular fibrillation (VF) occurring acutely after atrioventricular node (AVN) ablation. This patient had severe valvular cardiomyopathy, chronic atrial fibrillation (AF), and underwent prior to the AVN ablation a biventricular implantable cardiac defibrillator positioning. The VF was successfully cardioverted with one external electrical shock. What makes this presentation original is that the pre-ablation spontaneous heart rate in AF was slow (84 bpm), and that VF occurred after ablation despite a minimal heart rate drop of only 14 bpm. VF is the most feared complication of AVN ablation, but it had previously only been described in case of acute heart rate drop after ablation of at least 30 bpm (and more frequently>50 bpm). This case report highlights the fact that VF may occur after AVN ablation regardless of the heart rate drop, rendering temporary fast ventricular pacing mandatory whatever the pre-ablation heart rate. Copyright © 2016 Elsevier Masson SAS. All rights reserved.

  1. Leak Mitigation in Mechanically Pumped Fluid Loops for Long Duration Space Missions

    Science.gov (United States)

    Miller, Jennifer R.; Birur, Gajanana; Bame, David; Mastropietro, A. J.; Bhandari, Pradeep; Lee, Darlene; Karlmann, Paul; Liu, Yuanming

    2013-01-01

    Mechanically pumped fluid loops (MPFLs) are increasingly considered for spacecraft thermal control. A concern for long duration space missions is the leak of fluid leading to performance degradation or potential loop failure. An understanding of leak rate through analysis, as well as destructive and non-destructive testing, provides a verifiable means to quantify leak rates. The system can be appropriately designed to maintain safe operating pressures and temperatures throughout the mission. Two MPFLs on the Mars Science Laboratory Spacecraft, launched November 26, 2011, maintain the temperature of sensitive electronics and science instruments within a -40 deg C to 50 deg C range during launch, cruise, and Mars surface operations. With over 100 meters of complex tubing, fittings, joints, flex lines, and pumps, the system must maintain a minimum pressure through all phases of the mission to provide appropriate performance. This paper describes the process of design, qualification, test, verification, and validation of the components and assemblies employed to minimize risks associated with excessive fluid leaks from pumped fluid loop systems.

  2. Margins in high temperature leak-before-break assessments

    International Nuclear Information System (INIS)

    Budden, P.J.; Hooton, D.G.

    1997-01-01

    Developments in the defect assessment procedure R6 to include high-temperature mechanisms in Leak-before-Break arguments are described. In particular, the effect of creep on the time available to detect a leak and on the crack opening area, and hence leak rate, is discussed. The competing influence of these two effects is emphasized by an example. The application to Leak-before-Break of the time-dependent failure assessment diagram approach for high temperature defect assessment is then outlined. The approach is shown to be of use in assessing the erosion of margins by creep

  3. Margins in high temperature leak-before-break assessments

    Energy Technology Data Exchange (ETDEWEB)

    Budden, P.J.; Hooton, D.G.

    1997-04-01

    Developments in the defect assessment procedure R6 to include high-temperature mechanisms in Leak-before-Break arguments are described. In particular, the effect of creep on the time available to detect a leak and on the crack opening area, and hence leak rate, is discussed. The competing influence of these two effects is emphasized by an example. The application to Leak-before-Break of the time-dependent failure assessment diagram approach for high temperature defect assessment is then outlined. The approach is shown to be of use in assessing the erosion of margins by creep.

  4. New helium sniffing device for locating very fine leaks

    International Nuclear Information System (INIS)

    Murakami, Y.; Shimomura, Y.; Abe, T.; Obara, K.

    1984-01-01

    A new helium sniffing method for leak checking large vacuum vessels is described. The low sensitivity problem of the conventional helium sniffing method has been overcome by increasing the gas draw rate from around leaks into the detector up to about 0.1 Pa m 3 /s. The devised system consists of a flexible stainless steel capillary tube 0.6 mm i.d. and 10 m long, a sorption pump using molecular sieve, and a helium leak detector in series. This method is particularly useful for locating very fine leaks down to 10 -11 Pa m 3 /s. Relevant theoretical considerations and experimental results are presented

  5. Risk Factors for Gastrointestinal Leak after Bariatric Surgery: MBASQIP Analysis.

    Science.gov (United States)

    Alizadeh, Reza Fazl; Li, Shiri; Inaba, Colette; Penalosa, Patrick; Hinojosa, Marcelo W; Smith, Brian R; Stamos, Michael J; Nguyen, Ninh T

    2018-03-30

    Gastrointestinal leak remains one of the most dreaded complications in bariatric surgery. We aimed to evaluate risk factors and the impact of common perioperative interventions on the development of leak in patients who underwent laparoscopic bariatric surgery. Using the 2015 database of accredited centers, data were analyzed for patients who underwent laparoscopic sleeve gastrectomy or Roux-en-Y gastric bypass (LRYGB). Emergent, revisional, and converted cases were excluded. Multivariate logistic regression was used to analyze risk factors for leak, including provocative testing of anastomosis, surgical drain placement, and use of postoperative swallow study. Data from 133,478 patients who underwent laparoscopic sleeve gastrectomy (n = 92,495 [69.3%]) and LRYGB (n = 40,983 [30.7%]) were analyzed. Overall leak rate was 0.7% (938 of 133,478). Factors associated with increased risk for leak were oxygen dependency (adjusted odds ratio [AOR] 1.97), hypoalbuminemia (AOR 1.66), sleep apnea (AOR 1.52), hypertension (AOR 1.36), and diabetes (AOR 1.18). Compared with LRYGB, laparoscopic sleeve gastrectomy was associated with a lower risk of leak (AOR 0.52; 95% CI 0.44 to 0.61; p leak rate was higher in patients with vs without a provocative test (0.8% vs 0.4%, respectively; p leak rate was higher in patients with vs without a surgical drain placed (1.6% vs 0.4%, respectively; p leak rate was similar between patients with vs without swallow study (0.7% vs 0.7%; p = 0.50). The overall rate of gastrointestinal leak in bariatric surgery is low. Certain preoperative factors, procedural type (LRYGB), and interventions (intraoperative provocative test and surgical drain placement) were associated with a higher risk for leaks. Copyright © 2018 American College of Surgeons. Published by Elsevier Inc. All rights reserved.

  6. Leak processing system for valve gland portion

    International Nuclear Information System (INIS)

    Nishino, Masami

    1990-01-01

    When a process fluid for a valve to be checked is at such a normal temperature as during reactor operation, leaked fluid can be detected depending on the temperature increase accompanying the leakage. However, detection is difficult if the temperature of the process fluid for the valve to be checked is low and, if leakage is detected after the reactor start-up, repair has to be applied after the shutdown of the plant. Then, gland leak is detected by detecting the pressure instead of the temperature in the pipeline system and the leak flow rate is calculated based on the pressure. As a result, leakage is detected irrespective of the temperature of the leaked fluid and, for instance, leakage can be detected even in a case where the temperature is not high as in the case of pressure proof test for the pressure vessel before start-up. It can contribute much to the improvement of the plant operation efficiency and can determine the leak flow rate at a high accuracy. (N.H.)

  7. Hollow-core fiber sensing technique for pipeline leak detection

    Science.gov (United States)

    Challener, W. A.; Kasten, Matthias A.; Karp, Jason; Choudhury, Niloy

    2018-02-01

    Recently there has been increased interest on the part of federal and state regulators to detect and quantify emissions of methane, an important greenhouse gas, from various parts of the oil and gas infrastructure including well pads and pipelines. Pressure and/or flow anomalies are typically used to detect leaks along natural gas pipelines, but are generally very insensitive and subject to false alarms. We have developed a system to detect and localize methane leaks along gas pipelines that is an order of magnitude more sensitive by combining tunable diode laser spectroscopy (TDLAS) with conventional sensor tube technology. This technique can potentially localize leaks along pipelines up to 100 km lengths with an accuracy of +/-50 m or less. A sensor tube buried along the pipeline with a gas-permeable membrane collects leaking gas during a soak period. The leak plume within the tube is then carried to the nearest sensor node along the tube in a purge cycle. The time-to-detection is used to determine leak location. Multiple sensor nodes are situated along the pipeline to minimize the time to detection, and each node is composed of a short segment of hollow core fiber (HCF) into which leaking gas is transported quickly through a small pressure differential. The HCF sensing node is spliced to standard telecom solid core fiber which transports the laser light for spectroscopy to a remote interrogator. The interrogator is multiplexed across the sensor nodes to minimize equipment cost and complexity.

  8. FUZZY INFERENCE BASED LEAK ESTIMATION IN WATER PIPELINES SYSTEM

    OpenAIRE

    N. Lavanya; G. Anand; S. Srinivasan

    2015-01-01

    Pipeline networks are the most widely used mode for transporting fluids and gases around the world. Leakage in this pipeline causes harmful effects when the flowing fluid/gas is hazardous. Hence the detection of leak becomes essential to avoid/minimize such undesirable effects. This paper presents the leak detection by spectral analysis methods in a laboratory pipeline system. Transient in the pressure signal in the pipeline is created by opening and closing the exit valve. These pressure var...

  9. Does self-help increase rates of help seeking for student mental health problems by minimizing stigma as a barrier?

    Science.gov (United States)

    Levin, Michael E; Krafft, Jennifer; Levin, Crissa

    2018-01-01

    This study examined whether self-help (books, websites, mobile apps) increases help seeking for mental health problems among college students by minimizing stigma as a barrier. A survey was conducted with 200 college students reporting elevated distress from February to April 2017. Intentions to use self-help were low, but a significant portion of students unwilling to see mental health professionals intended to use self-help. Greater self-stigma related to lower intentions to seek professional help, but was unrelated to seeking self-help. Similarly, students who only used self-help in the past reported higher self-stigma than those who sought professional treatment in the past. Although stigma was not a barrier for self-help, alternate barriers were identified. Offering self-help may increase rates of students receiving help for mental health problems, possibly by offering an alternative for students unwilling to seek in-person therapy due to stigma concerns.

  10. Specificity and sensitivity of noninvasive measurement of pulmonary vascular protein leak

    International Nuclear Information System (INIS)

    Dauber, I.M.; Pluss, W.T.; VanGrondelle, A.; Trow, R.S.; Weil, J.V.

    1985-01-01

    Noninvasive techniques employing external counting of radiolabeled protein have the potential for measuring pulmonary vascular protein permeability, but their specificity and sensitivity remain unclear. The authors tested the specificity and sensitivity of a double-radioisotope method by injecting radiolabeled albumin ( 131 I) and erythrocytes (/sup 99m/Tc) into anesthetized dogs and measuring the counts of each isotope for 150 min after injection with an external gamma probe fixed over the lung. They calculated the rate of increase of albumin counts measured by the probe (which reflects the rate at which protein leaks into the extravascular space). To assess permeability the authors normalized the rate of increase in albumin counts for changes in labeled erythrocyte signal to minimize influence of changes in vascular surface area and thus derived an albumin leak index. They measured the albumin leak index and gravimetric lung water during hydrostatic edema (acutely elevating left atrial pressure by left atrial balloon inflation: mean pulmonary arterial wedge pressure = 22.6 Torr) and in lung injury edema induced by high- (1.0 g/kg) and low-dose (0.25 g/kg) intravenous thiourea. To test specificity hydrostatic and high-dose thiourea edema were compared. The albumin leak index increased nearly fourfold from control after thiourea injury (27.2 +/- 2.3 x 10-4 vs. 7.6 +/- 0.9 x 10-4 min-1) but did not change from control levels after elevating left atrial pressure (8.9 +/- 1.2 x 10-4 min-1) despite comparable increases in gravimetric lung water. To test sensitivity the authors compared low-dose thiourea with controls. Following low-dose thiourea, the albumin leak index nearly doubled despite the absence of a measurable increase in lung water

  11. Current practice and developmental efforts for leak detection in U.S. reactor primary systems

    International Nuclear Information System (INIS)

    Kupperman, D.S.; Claytor, T.N.

    1986-01-01

    Current leak detection practices in 74 operating nuclear reactors have been reviewed. Existing leak detection systems are adequate to ensure a leak-before-break scenario in most situations, but no currently available, single method combines optimal leakage detection sensitivity, leak-locating ability, and leakage measurement accuracy. Simply tightening current leakage limits may produce an unacceptably large number of unnecessary shutdowns. The use of commercially available acoustic monitoring systems or moisture-sensitive tape may improve leak detection capability at specific sites. However, neither of these methods currently provides source discrimination (e.g., to distinguish between leaks from pipe cracks and valves) or leak-rate information (a small leak may saturate the system). A field-implementable acoustic leak detection system is being developed to address these limitations. 5 refs.

  12. Current practice and developmental efforts for leak detection in US reactor primary systems

    International Nuclear Information System (INIS)

    Kupperman, D.S.; Claytor, T.N.

    1985-07-01

    Current leak detection practices in 74 operating nuclear reactors have been reviewed. Existing leak detection systems are adequate to ensure a leak-before-break scenario in most situations, but no currently available, single method combines optimal leakage detection sensitivity, leak-locating ability, and leakage measurement accuracy. Simply tightening current leakage limits may produce an unacceptably large number of unnecessary shutdowns. The use of commercially available acoustic monitoring systems or moisture-sensitive tape may improve leak detection capability at specific sites. However, neither of these methods currently provides source discrimination (e.g., to distinguish between leaks from pipe cracks and valves) or leak-rate information (a small leak may saturate the system). A field-implementable acoustic leak detection system is being developed to address these limitations. 5 refs., 3 figs

  13. Single-Shell Tank Leak Integrity Summary

    Energy Technology Data Exchange (ETDEWEB)

    Harlow, D. G. [Washington River Protection Solutions LLC, Richland, WA (United States); Girardot, C. L. [Washington River Protection Solutions LLC, Richland, WA (United States); Venetz, T. J. [Washington River Protection Solutions LLC, Richland, WA (United States)

    2015-03-26

    This document summarizes and evaluates the information in the Hanford Tri-Party Agreement Interim Milestone M-045-91F Targets completed between 2010 and 2015. 1) Common factors of SST liner failures (M-045-91F-T02), 2) the feasibility of testing for ionic conductivity between the inside and outside of SSTs (M-045-91F-T03, and 3) the causes, locations, and rates of leaks from leaking SSTs (M-045-91F-T04).

  14. Hazardous fluid leak detector

    Science.gov (United States)

    Gray, Harold E.; McLaurin, Felder M.; Ortiz, Monico; Huth, William A.

    1996-01-01

    A device or system for monitoring for the presence of leaks from a hazardous fluid is disclosed which uses two electrodes immersed in deionized water. A gas is passed through an enclosed space in which a hazardous fluid is contained. Any fumes, vapors, etc. escaping from the containment of the hazardous fluid in the enclosed space are entrained in the gas passing through the enclosed space and transported to a closed vessel containing deionized water and two electrodes partially immersed in the deionized water. The electrodes are connected in series with a power source and a signal, whereby when a sufficient number of ions enter the water from the gas being bubbled through it (indicative of a leak), the water will begin to conduct, thereby allowing current to flow through the water from one electrode to the other electrode to complete the circuit and activate the signal.

  15. Natural gas leak mapper

    Science.gov (United States)

    Reichardt, Thomas A [Livermore, CA; Luong, Amy Khai [Dublin, CA; Kulp, Thomas J [Livermore, CA; Devdas, Sanjay [Albany, CA

    2008-05-20

    A system is described that is suitable for use in determining the location of leaks of gases having a background concentration. The system is a point-wise backscatter absorption gas measurement system that measures absorption and distance to each point of an image. The absorption measurement provides an indication of the total amount of a gas of interest, and the distance provides an estimate of the background concentration of gas. The distance is measured from the time-of-flight of laser pulse that is generated along with the absorption measurement light. The measurements are formated into an image of the presence of gas in excess of the background. Alternatively, an image of the scene is superimosed on the image of the gas to aid in locating leaks. By further modeling excess gas as a plume having a known concentration profile, the present system provides an estimate of the maximum concentration of the gas of interest.

  16. Recent Progress in Technology of Leak detection

    Energy Technology Data Exchange (ETDEWEB)

    Jung, H. K.; Kim, S. H.; Cho, J. W.; Joo, Y. S.; Yang, D. J

    2005-07-15

    It is very important to check for leakage points of fluids and gases on primary pressure boundary of nuclear power plants in order to maintain and manage various structures safely. Even though much investigation has been performed by a number of researchers, there are a lot of problems to detect the leakage under some areas to which people can not approach. In particular, it is certainly necessary to find the leakage point in order to repair and replace the pressure boundaries. In this report, the basic principle and application situations for the development of the leak detection system which can detect micro-leaks are introduced. As the technologies and performances of recent sensors have been improving, the application range of leak detection has been increasing steadily. Therefore the sensor technologies written in this report will be able to contribute to nuclear safety to detect the leakage rate and the leakage point with an on-line monitoring system in the near future.

  17. Does a dyon leak

    International Nuclear Information System (INIS)

    Grossman, B.

    1983-01-01

    In the presence of a CP-nonconservation measured by an angle theta, the ground state of a point magnetic monopole is shown to have an electric charge of value -etheta/2π which changes discontinuously to zero for massless fermions. A new version of Levinson's theorem is also given. The latter effect as well as the S-wave helicity flip of a dyon can be interpreted as a leak at the origin

  18. Aspects of leak detection

    International Nuclear Information System (INIS)

    Chivers, T.C.

    1997-01-01

    A requirement of a Leak before Break safety case is that the leakage from the through wall crack be detected prior to any growth leading to unacceptable failure. This paper sets out to review some recent developments in this field. It does not set out to be a comprehensive guide to all of the methods available. The discussion concentrates on acoustic emission and how the techniques can be qualified and deployed on operational plant

  19. Aspects of leak detection

    Energy Technology Data Exchange (ETDEWEB)

    Chivers, T.C. [Berkeley Technology Centre, Glos (United Kingdom)

    1997-04-01

    A requirement of a Leak before Break safety case is that the leakage from the through wall crack be detected prior to any growth leading to unacceptable failure. This paper sets out to review some recent developments in this field. It does not set out to be a comprehensive guide to all of the methods available. The discussion concentrates on acoustic emission and how the techniques can be qualified and deployed on operational plant.

  20. Reliability evaluation of the Savannah River reactor leak detection system

    International Nuclear Information System (INIS)

    Daugherty, W.L.; Sindelar, R.L.; Wallace, I.T.

    1991-01-01

    The Savannah River Reactors have been in operation since the mid-1950's. The primary degradation mode for the primary coolant loop piping is intergranular stress corrosion cracking. The leak-before-break (LBB) capability of the primary system piping has been demonstrated as part of an overall structural integrity evaluation. One element of the LBB analyses is a reliability evaluation of the leak detection system. The most sensitive element of the leak detection system is the airborne tritium monitors. The presence of small amounts of tritium in the heavy water coolant provide the basis for a very sensitive system of leak detection. The reliability of the tritium monitors to properly identify a crack leaking at a rate of either 50 or 300 lb/day (0.004 or 0.023 gpm, respectively) has been characterized. These leak rates correspond to action points for which specific operator actions are required. High reliability has been demonstrated using standard fault tree techniques. The probability of not detecting a leak within an assumed mission time of 24 hours is estimated to be approximately 5 x 10 -5 per demand. This result is obtained for both leak rates considered. The methodology and assumptions used to obtain this result are described in this paper. 3 refs., 1 fig., 1 tab

  1. Vehicle-based Methane Mapping Helps Find Natural Gas Leaks and Prioritize Leak Repairs

    Science.gov (United States)

    von Fischer, J. C.; Weller, Z.; Roscioli, J. R.; Lamb, B. K.; Ferrara, T.

    2017-12-01

    Recently, mobile methane sensing platforms have been developed to detect and locate natural gas (NG) leaks in urban distribution systems and to estimate their size. Although this technology has already been used in targeted deployment for prioritization of NG pipeline infrastructure repair and replacement, one open question regarding this technology is how effective the resulting data are for prioritizing infrastructure repair and replacement. To answer this question we explore the accuracy and precision of the natural gas leak location and emission estimates provided by methane sensors placed on Google Street View (GSV) vehicles. We find that the vast majority (75%) of methane emitting sources detected by these mobile platforms are NG leaks and that the location estimates are effective at identifying the general location of leaks. We also show that the emission rate estimates from mobile detection platforms are able to effectively rank NG leaks for prioritizing leak repair. Our findings establish that mobile sensing platforms are an efficient and effective tool for improving the safety and reducing the environmental impacts of low-pressure NG distribution systems by reducing atmospheric methane emissions.

  2. Fully automatic AI-based leak detection system

    Energy Technology Data Exchange (ETDEWEB)

    Tylman, Wojciech; Kolczynski, Jakub [Dept. of Microelectronics and Computer Science, Technical University of Lodz in Poland, ul. Wolczanska 221/223, Lodz (Poland); Anders, George J. [Kinectrics Inc., 800 Kipling Ave., Toronto, Ontario M8Z 6C4 (Canada)

    2010-09-15

    This paper presents a fully automatic system intended to detect leaks of dielectric fluid in underground high-pressure, fluid-filled (HPFF) cables. The system combines a number of artificial intelligence (AI) and data processing techniques to achieve high detection capabilities for various rates of leaks, including leaks as small as 15 l per hour. The system achieves this level of precision mainly thanks to a novel auto-tuning procedure, enabling learning of the Bayesian network - the decision-making component of the system - using simulated leaks of various rates. Significant new developments extending the capabilities of the original leak detection system described in and form the basis of this paper. Tests conducted on the real-life HPFF cable system in New York City are also discussed. (author)

  3. Leak detection and localization system through acoustics; Sistema de deteccao e localizacao de vazamentos por acustica

    Energy Technology Data Exchange (ETDEWEB)

    Alonso, Julio [Aselco Automacao, Sao Paulo, SP (Brazil)

    2003-07-01

    Acoustic Leak Detection Systems (ALDS) are used on both liquid and gas pipelines as well as multi-phase flow pipelines to detect leaks quickly and provide a means of limiting product loss. The real-time acoustic signal is continuously compared against signature leak profiles for the particular operating and geometric conditions. These profiles were developed from a database established from over 20 years of experimental and field leak tests. This technique not only drastically reduces the false alarm rate, but also significantly improves the sensitivity and leak location accuracy. This system will also detect leaks with shut-in flow (zero flow rate in the pipeline). With the use of GPS (Global Positioning System) it not only improves leak location accuracy, but also allows for continuous leak detection during the loss of communications. (author)

  4. Sealing of leaks in the bioshield cooling system of three research reactors

    International Nuclear Information System (INIS)

    May, R.; Taylor, M.F.

    1995-01-01

    Water leaks have occurred in the bioshield cooling system of three research reactors. These leaks have been plugged with a sealant based on a blend of a water-based resin and a bentonite-type clay originally developed for sealing similar leaks on power reactors. The mechanism of sealing and development testing of the sealant are described. Application of the sealant to the three reactors sealed the leaks. However, unlike experience with leaks in steel and aluminium systems, some leaks reappeared after several months service - albeit at a leak rate only a very small fraction of the original leak rate. The recurrent defects were readily retreated with sealant and hence, in these instances, the treatment is an effective maintenance procedure for any ageing reactor rather than a permanent cure. (orig.)

  5. Viscous Corrections of the Time Incremental Minimization Scheme and Visco-Energetic Solutions to Rate-Independent Evolution Problems

    Science.gov (United States)

    Minotti, Luca; Savaré, Giuseppe

    2018-02-01

    We propose the new notion of Visco-Energetic solutions to rate-independent systems {(X, E,} d) driven by a time dependent energy E and a dissipation quasi-distance d in a general metric-topological space X. As for the classic Energetic approach, solutions can be obtained by solving a modified time Incremental Minimization Scheme, where at each step the dissipation quasi-distance d is incremented by a viscous correction {δ} (for example proportional to the square of the distance d), which penalizes far distance jumps by inducing a localized version of the stability condition. We prove a general convergence result and a typical characterization by Stability and Energy Balance in a setting comparable to the standard energetic one, thus capable of covering a wide range of applications. The new refined Energy Balance condition compensates for the localized stability and provides a careful description of the jump behavior: at every jump the solution follows an optimal transition, which resembles in a suitable variational sense the discrete scheme that has been implemented for the whole construction.

  6. Novel Methods of Hydrogen Leak Detection

    International Nuclear Information System (INIS)

    Pushpinder S Puri

    2006-01-01

    With the advent of the fuel cell technology and a drive for clean fuel, hydrogen gas is emerging as a leading candidate for the fuel of choice. For hydrogen to become a consumer fuel for automotive and domestic power generation, safety is paramount. It is, therefore, desired to have a method and system for hydrogen leak detection using odorant which can incorporate a uniform concentration of odorant in the hydrogen gas, when odorants are mixed in the hydrogen storage or delivery means. It is also desired to develop methods where the odorant is not added to the bulk hydrogen, keeping it free of the odorization additives. When odorants are not added to the hydrogen gas in the storage or delivery means, methods must be developed to incorporate odorant in the leaking gas so that leaks can be detected by small. Further, when odorants are not added to the stored hydrogen, it may also be desirable to observe leaks by sight by discoloration of the surface of the storage or transportation vessels. A series of novel solutions are proposed which address the issues raised above. These solutions are divided into three categories as follows: 1. Methods incorporating an odorant in the path of hydrogen leak as opposed to adding it to the hydrogen gas. 2. Methods where odorants are generated in-situ by chemical reaction with the leaking hydrogen 3. Methods of dispensing and storing odorants in high pressure hydrogen gas which release odorants to the gas at a uniform and predetermined rates. Use of one or more of the methods described here in conjunction with appropriate engineering solutions will assure the ultimate safety of hydrogen use as a commercial fuel. (authors)

  7. Transcriptomics and molecular evolutionary rate analysis of the bladderwort (Utricularia, a carnivorous plant with a minimal genome

    Directory of Open Access Journals (Sweden)

    Herrera-Estrella Alfredo

    2011-06-01

    Full Text Available Abstract Background The carnivorous plant Utricularia gibba (bladderwort is remarkable in having a minute genome, which at ca. 80 megabases is approximately half that of Arabidopsis. Bladderworts show an incredible diversity of forms surrounding a defined theme: tiny, bladder-like suction traps on terrestrial, epiphytic, or aquatic plants with a diversity of unusual vegetative forms. Utricularia plants, which are rootless, are also anomalous in physiological features (respiration and carbon distribution, and highly enhanced molecular evolutionary rates in chloroplast, mitochondrial and nuclear ribosomal sequences. Despite great interest in the genus, no genomic resources exist for Utricularia, and the substitution rate increase has received limited study. Results Here we describe the sequencing and analysis of the Utricularia gibba transcriptome. Three different organs were surveyed, the traps, the vegetative shoot bodies, and the inflorescence stems. We also examined the bladderwort transcriptome under diverse stress conditions. We detail aspects of functional classification, tissue similarity, nitrogen and phosphorus metabolism, respiration, DNA repair, and detoxification of reactive oxygen species (ROS. Long contigs of plastid and mitochondrial genomes, as well as sequences for 100 individual nuclear genes, were compared with those of other plants to better establish information on molecular evolutionary rates. Conclusion The Utricularia transcriptome provides a detailed genomic window into processes occurring in a carnivorous plant. It contains a deep representation of the complex metabolic pathways that characterize a putative minimal plant genome, permitting its use as a source of genomic information to explore the structural, functional, and evolutionary diversity of the genus. Vegetative shoots and traps are the most similar organs by functional classification of their transcriptome, the traps expressing hydrolytic enzymes for prey

  8. Leak testing at Westinghouse Hanford Company for the Fast Flux Test Facility (FFTF)

    International Nuclear Information System (INIS)

    Jackson, C.N.

    1981-01-01

    Described leak testing applications require an arsenal of test equipment, a diverse range of testing techniques and a cadre of technical talent. A wide range helium mass spectrometer leak detector, a volume change tester and a halogen detector are employed to cover the 1 x 10 -8 to 1 atm cc/sec leak rate range encountered. Leak testing techniques, equipment problems, costs, and recommendations are discussed for examination of reactor pressure boundary and other ancillary components of the FFTF

  9. Mobile leak testing system

    International Nuclear Information System (INIS)

    Ungr, F.

    The design and implementation are described of a mobile testing unit ULTRATEST M for helium leak tests. The equipment has been developed by Leybold-Heraeus GmbH in Cologne and is in-built in a Mercedes-Benz 208 van. The equipment is designed for the operative use in assembly and construction of nuclear power plants and its throughput is sufficient for checking the whole upper reactor block. It may also be used for removing defects of vacuum equipment requiring a high level of tightness or equally demanding equipment used in the chemical industry. Experience with the equipment is described. (B.S.)

  10. Reliability of leak detection systems in light water reactors

    International Nuclear Information System (INIS)

    Kupperman, D.S.

    1987-01-01

    US Nuclear Regulatory Commission Guide 1.45 recommends the use of at least three different detection methods in reactors to detect leakage. Monitoring of both sump-flow and airborne particulate radioactivity is recommended. A third method can involve either monitoring of condensate flow rate from air coolers or monitoring of airborne gaseous radioactivity. Although the methods currently used for leak detection reflect the state of the art, other techniques may be developed and used. Since the recommendations of Regulatory Guide 1.45 are not mandatory, the technical specifications for 74 operating plants have been reviewed to determine the types of leak detection methods employed. In addition, Licensee Event Report (LER) Compilations from June 1985 to June 1986 have been reviewed to help establish actual capabilities for detecting leaks and determining their source. Work at Argonne National Laboratory has demonstrated that improvements in leak detection, location, and sizing are possible with advanced acoustic leak detection technology

  11. Deconstructing Gender Stereotypes in Leak

    Directory of Open Access Journals (Sweden)

    Nengah Bawa Atmadja

    2015-05-01

    Full Text Available The belief of Balinese people towards leak still survive. Leak is a magic based on durgaism that can transform a person from human to another form, such as apes, pigs, etc. People tend to regard leak as evil. In general, the evilness is constructed in gender stereotypes, so it is identified that leak are always women. This idea is a power game based on the ideology of patriarchy that provides legitimacy for men to dominate women with a plea for social harmony. As a result, women are marginalized in the Balinese society. Women should be aware of so it would provide encouragement for them to make emancipatory changes dialogically. Kepercayaan orang Bali terhadap leak tetap bertahan sampai saat ini. Leak adalah sihir yang berbasiskan durgaisme yang dapat mengakibatkan seseorang bisa merubah bentuk dari manusia ke wujud yang lain, misalnya kera, babi, dll. Leak termasuk magi hitam sehingga dinilai bersifat jelek. Pada umumnya perempuan diidentikkan dengan leak sehingga melahirkan asumsi yang bermuatan steriotip gender bahwa leak = perempuan. Gagasan ini merupakan permainan kekuasaan berbasis ideologi patriarkhi dan sekaligus memberikan legitimasi bagi laki-laki untuk menguasai perempuan dengan dalih demi keharmonisan sosial. Akibatnya, perempuan menjadi termarginalisasi pada masyarakat Bali.  Perempuan harus menyadarinya sehingga memberikan dorongan bagi mereka untuk melakukan perubahan secara dialogis emansipatoris.

  12. Intraoperative air leak measured after lobectomy is associated with postoperative duration of air leak.

    Science.gov (United States)

    Brunelli, Alessandro; Salati, Michele; Pompili, Cecilia; Gentili, Paolo; Sabbatini, Armando

    2017-11-01

    To verify the association between the air leak objectively measured intraoperatively (IAL) using the ventilator and the air leak duration after pulmonary lobectomy. Prospective analysis on 111 patients submitted to pulmonary lobectomy (33 by video-assisted thoracic surgery). After resection, objective assessment of air leak (in milliliter per minute) was performed before closure of the chest by measuring the difference between a fixed inspired and expired volume, using a tidal volume of 8 ml/kg, a respiratory rate of 10 and a positive-end expiratory pressure of 5 cmH2O. A multivariable analysis was performed for identifying factors associated with duration of postoperative air leak. Average IAL was 158 ml/min (range 0-1500 ml/min). The best cut-off (receiver-operating characteristics analysis) associated with air leak longer than 5 days was 500 ml/min. Nine patients had IAL >500 ml/min (8%). They had a longer duration of postoperative air leak compared with those with a lower IAL (mean values, 10.1 days, SD 8.8 vs 1.5 days, SD 4.9 P leak duration after multivariable regression: left side resection (P = 0.018), upper site resection (P = 0.031) and IAL >500 ml/min (P leak duration was generated: 1.7 + 2.4 × left side + 2.2 × upper site + 8.8 × IAL >500. The air leak measurement using the ventilator parameters after lung resection may assist in estimating the risk of postoperative prolonged air leak. An IAL > 500 ml/min may warrant the use of intraoperative preventative measures, particularly after video-assisted thoracic surgery lobectomy where a submersion test is often unreliable. © 2017 European Society of Cardiology and European Atherosclerosis Association. All rights reserved. For permissions please email: journals.permissions@oup.com.

  13. Radiation leaking protection device

    International Nuclear Information System (INIS)

    Sunami, Yoshio; Mitsumori, Kojiro

    1980-01-01

    Purpose: To prevent radioactivity from leaking outside of a reactor container by way of pipeways passing therethrough, by supplying pressurized fluid between each of a plurality of valves for separating the pipeways. Constitution: Pressurized fluid is supplied between each of a plurality of valves for separating pipeways. For instance, water in a purified water tank is pressurized by a pressure pump and the pressure of the pressurized water is controlled by a differential pressure detector, a pressure controller and a pressure control valve. In the case if a main steam pipe is ruptured outside of the reactor container or to be repaired, the separation valves are wholly closed and then the pressurizing device is actuated to supply pressurized water containing no radioactivity from the purified water tank to the position between the valves. The pressure in the pressurized water is controlled such that it is always higher by a predetermined level than the pressure in the reactor. This prevents the radioacitivity in the reactor core from leaking outside of the container passing through the valves, whereby radiation exposure in the working can be reduced and the circumferential contamination upon accident of pipeway rupture can be decreased. (Kawakami, Y.)

  14. CSNI specialist meeting on leak-before-break in nuclear reactor piping: proceedings

    Energy Technology Data Exchange (ETDEWEB)

    1984-08-01

    On September 1 and 2, 1983, the CSNI subcommittee on primary system integrity held a special meeting in Monterey, California, on the subject of leak-before-break in nuclear reactor piping systems. The purpose of the meeting was to provide an international forum for the exchange of ideas, positions, and research results; to identify areas requiring additional research and development; and to determine the general attitude toward acceptance of the leak-before-break concept. The importance of the leak-before-break issue was evidenced by excellent attendance at the meeting and through active participation by the meeting attendees. Approximately 125 people representing fifteen different nations attended the meeting. The meeting was divided into four technical sessions addressing the following areas: Application of Piping Fracture Mechanics to Leak-Before Break, Leak Rate and Leak Detection, Leak-Before-Break Studies, Methods and Results, Current and Proposed Positions on Leak-Before-Break.

  15. CSNI specialist meeting on leak-before-break in nuclear reactor piping: proceedings

    International Nuclear Information System (INIS)

    1984-08-01

    On September 1 and 2, 1983, the CSNI subcommittee on primary system integrity held a special meeting in Monterey, California, on the subject of leak-before-break in nuclear reactor piping systems. The purpose of the meeting was to provide an international forum for the exchange of ideas, positions, and research results; to identify areas requiring additional research and development; and to determine the general attitude toward acceptance of the leak-before-break concept. The importance of the leak-before-break issue was evidenced by excellent attendance at the meeting and through active participation by the meeting attendees. Approximately 125 people representing fifteen different nations attended the meeting. The meeting was divided into four technical sessions addressing the following areas: Application of Piping Fracture Mechanics to Leak-Before Break, Leak Rate and Leak Detection, Leak-Before-Break Studies, Methods and Results, Current and Proposed Positions on Leak-Before-Break

  16. 40 CFR 63.1005 - Leak repair.

    Science.gov (United States)

    2010-07-01

    ... 40 Protection of Environment 10 2010-07-01 2010-07-01 false Leak repair. 63.1005 Section 63.1005... Standards for Equipment Leaks-Control Level 1 § 63.1005 Leak repair. (a) Leak repair schedule. The owner or operator shall repair each leak detected no later than 15 calendar days after it is detected, except as...

  17. 40 CFR 63.1024 - Leak repair.

    Science.gov (United States)

    2010-07-01

    ... 40 Protection of Environment 10 2010-07-01 2010-07-01 false Leak repair. 63.1024 Section 63.1024... Standards for Equipment Leaks-Control Level 2 Standards § 63.1024 Leak repair. (a) Leak repair schedule. The owner or operator shall repair each leak detected as soon as practical, but not later than 15 calendar...

  18. 40 CFR 65.105 - Leak repair.

    Science.gov (United States)

    2010-07-01

    ... 40 Protection of Environment 15 2010-07-01 2010-07-01 false Leak repair. 65.105 Section 65.105... FEDERAL AIR RULE Equipment Leaks § 65.105 Leak repair. (a) Leak repair schedule. The owner or operator shall repair each leak detected as soon as practical but not later than 15 calendar days after it is...

  19. ISS Ammonia Leak Detection Through X-Ray Fluorescence

    Science.gov (United States)

    Camp, Jordan; Barthelmy, Scott; Skinner, Gerry

    2013-01-01

    Ammonia leaks are a significant concern for the International Space Station (ISS). The ISS has external transport lines that direct liquid ammonia to radiator panels where the ammonia is cooled and then brought back to thermal control units. These transport lines and radiator panels are subject to stress from micrometeorites and temperature variations, and have developed small leaks. The ISS can accommodate these leaks at their present rate, but if the rate increased by a factor of ten, it could potentially deplete the ammonia supply and impact the proper functioning of the ISS thermal control system, causing a serious safety risk. A proposed ISS astrophysics instrument, the Lobster X-Ray Monitor, can be used to detect and localize ISS ammonia leaks. Based on the optical design of the eye of its namesake crustacean, the Lobster detector gives simultaneously large field of view and good position resolution. The leak detection principle is that the nitrogen in the leaking ammonia will be ionized by X-rays from the Sun, and then emit its own characteristic Xray signal. The Lobster instrument, nominally facing zenith for its astrophysics observations, can be periodically pointed towards the ISS radiator panels and some sections of the transport lines to detect and localize the characteristic X-rays from the ammonia leaks. Another possibility is to use the ISS robot arm to grab the Lobster instrument and scan it across the transport lines and radiator panels. In this case the leak detection can be made more sensitive by including a focused 100-microampere electron beam to stimulate X-ray emission from the leaking nitrogen. Laboratory studies have shown that either approach can be used to locate ammonia leaks at the level of 0.1 kg/day, a threshold rate of concern for the ISS. The Lobster instrument uses two main components: (1) a microchannel plate optic (also known as a Lobster optic) that focuses the X-rays and directs them to the focal plane, and (2) a CCD (charge

  20. Chemochromic Hydrogen Leak Detectors

    Science.gov (United States)

    Roberson, Luke; Captain, Janine; Williams, Martha; Smith, Trent; Tate, LaNetra; Raissi, Ali; Mohajeri, Nahid; Muradov, Nazim; Bokerman, Gary

    2009-01-01

    At NASA, hydrogen safety is a key concern for space shuttle processing. Leaks of any level must be quickly recognized and addressed due to hydrogen s lower explosion limit. Chemo - chromic devices have been developed to detect hydrogen gas in several embodiments. Because hydrogen is odorless and colorless and poses an explosion hazard, there is an emerging need for sensors to quickly and accurately detect low levels of leaking hydrogen in fuel cells and other advanced energy- generating systems in which hydrogen is used as fuel. The device incorporates a chemo - chromic pigment into a base polymer. The article can reversibly or irreversibly change color upon exposure to hydrogen. The irreversible pigment changes color from a light beige to a dark gray. The sensitivity of the pigment can be tailored to its application by altering its exposure to gas through the incorporation of one or more additives or polymer matrix. Furthermore, through the incorporation of insulating additives, the chemochromic sensor can operate at cryogenic temperatures as low as 78 K. A chemochromic detector of this type can be manufactured into any feasible polymer part including injection molded plastic parts, fiber-spun textiles, or extruded tapes. The detectors are simple, inexpensive, portable, and do not require an external power source. The chemochromic detectors were installed and removed easily at the KSC launch pad without need for special expertise. These detectors may require an external monitor such as the human eye, camera, or electronic detector; however, they could be left in place, unmonitored, and examined later for color change to determine whether there had been exposure to hydrogen. In one type of envisioned application, chemochromic detectors would be fabricated as outer layers (e.g., casings or coatings) on high-pressure hydrogen storage tanks and other components of hydrogen-handling systems to provide visible indications of hydrogen leaks caused by fatigue failures or

  1. Acoustic Leak Detection under Micro and Small Water Steam Leaks into Sodium for a Protection of the SFR Steam Generator

    International Nuclear Information System (INIS)

    Kim, Tae-Joon; Jeong, Ji-Young; Kim, Jong-Man; Kim, Byung-Ho; Hahn, Do-Hee; Yugay, Valeriy S.

    2008-01-01

    The results of an experimental study of water in a sodium leak noise spectrum formation related with a leak noise attenuation and absorption, and at various rates of water into a sodium leak, smaller than 1.0 g/s, are presented. We focused on studying the micro leak dynamics with an increasing rate of water into sodium owing to a self-development from 0.005 till 0.27 g/s. Conditions and ranges for the existence of bubbling and jetting modes in a water steam outflow into circulating sodium through an injector device, for simulating a defect in a wall of a heat-transmitting tube of a sodium water steam generator were determined. On the basis of the experimental leak noise data the simple dependency of an acoustic signal level from the rate of a micro and small leak at different frequency bands is presented to understand the principal analysis for the development of an acoustic leak detection methodology used in a K- 600 steam generator, with the operational experiences for the noise analysis and measurements in BN-600

  2. Steam leak detection in advance reactors via acoustics method

    International Nuclear Information System (INIS)

    Singh, Raj Kumar; Rao, A. Rama

    2011-01-01

    Highlights: → Steam leak detection system is developed to detect any leak inside the reactor vault. → The technique uses leak noise frequency spectrum for leak detection. → Testing of system and method to locate the leak is also developed and discussed in present paper. - Abstract: Prediction of LOCA (loss of coolant activity) plays very important role in safety of nuclear reactor. Coolant is responsible for heat transfer from fuel bundles. Loss of coolant is an accidental situation which requires immediate shut down of reactor. Fall in system pressure during LOCA is the trip parameter used for initiating automatic reactor shut down. However, in primary heat transport system operating in two phase regimes, detection of small break LOCA is not simple. Due to very slow leak rates, time for the fall of pressure is significantly slow. From reactor safety point of view, it is extremely important to find reliable and effective alternative for detecting slow pressure drop in case of small break LOCA. One such technique is the acoustic signal caused by LOCA in small breaks. In boiling water reactors whose primary heat transport is to be driven by natural circulation, small break LOCA detection is important. For prompt action on post small break LOCA, steam leak detection system is developed to detect any leak inside the reactor vault. The detection technique is reliable and plays a very important role in ensuring safety of the reactor. Methodology developed for steam leak detection is discussed in present paper. The methods to locate the leak is also developed and discussed in present paper which is based on analysis of the signal.

  3. Tank car leaks gasoline

    International Nuclear Information System (INIS)

    Anon.

    1997-01-01

    On January 27, 1994, a Canadian National (CN) tank car loaded with gasoline began to leak from a crack in the tank shell on the end of the car near the stub sill. The tank car had been damaged from impact switching. A part of the tank car was sent for laboratory analysis which concluded that: (1) the fracture originated in two locations in welds, (2) the cracks propagated in a symmetrical manner and progressed into the tank plate, (3) the fracture surface revealed inadequate weld fusion. A stress analysis of the tank car was conducted to determine the coupling force necessary to cause the crack. It was noted that over the last decade several problems have occurred pertaining to stub sill areas of tank cars that have resulted in hazardous material spills. An advisory was sent to Transport Canada outlining many examples where tank cars containing serious defects had passed CN inspections that were specifically designed to identify such defects. 4 figs

  4. The Leaking Pipeline

    DEFF Research Database (Denmark)

    Henningsen, Inge; Højgaard, Lis

    2002-01-01

    negotiations of cultural prescriptions of gendered subjectivity and identities, organizational understandings and procedures embedded in specific university cultures, traditional of different science disciplines, and the systemic logic and political rationale of the education and research system....... these positions, and one that maintains that a closer look at the statistics does not support this optimism because women’s percentage in recruitment positions is not increasing as the pool of potential female researchers increases, or to put it metaphorically, “the pipeline is leaking women all along” (Alper...... it identifies and describes a Danish verion of ‘the leaky pipeline’ from analyses of the ratios of women in science from high school through tenured positions. Finally it illustrates the cultural mechanisms at play in this process, based on the results of three studies. The first two analyze the educational...

  5. Detection of steam generator tube leaks in pressurized water reactors

    International Nuclear Information System (INIS)

    Roach, W.H.

    1985-01-01

    This report addresses the early detection of small steam generator tube leaks in pressurized water reactors. It discusses the third, and final, year's work on an NRC-funded project examining diagnostic instrumentation in water reactors. The first two years were broad in coverage, concentrating on anticipatory measurements for detection of potential problems in both pressurized- and boiling-water reactors, with recommendations for areas of further study. One of these areas, the early detection of small steam tube leaks in PWRs, formed the basis of study for the last year of the project. Four tasks are addressed in this study of the detection of steam tube leaks. (1) Determination of which physical parameters indicate the onset of steam generator tube leaks. (2) Establishing performance goals for diagnostic instruments which could be used for early detection of steam generator tube leaks. (3) Defining the diagnostic instrumentation and their location which satisfy Items 1 and 2 above. (4) Assessing the need for diagnostic data processing and display. Parameters are identified, performance goals established, and sensor types and locations are specified in the report, with emphasis on the use of existing instrumentation with a minimum of retrofitting. A simple algorithm is developed which yields the leak rate as a function of known or measurable quantities. The conclusion is that leak rates of less than one-tenth gram per second should be detectable with existing instrumentation. (orig./HP)

  6. What Does It Take to Change an Editor's Mind? Identifying Minimally Important Difference Thresholds for Peer Reviewer Rating Scores of Scientific Articles.

    Science.gov (United States)

    Callaham, Michael; John, Leslie K

    2018-01-05

    We define a minimally important difference for the Likert-type scores frequently used in scientific peer review (similar to existing minimally important differences for scores in clinical medicine). The magnitude of score change required to change editorial decisions has not been studied, to our knowledge. Experienced editors at a journal in the top 6% by impact factor were asked how large a change of rating in "overall desirability for publication" was required to trigger a change in their initial decision on an article. Minimally important differences were assessed twice for each editor: once assessing the rating change required to shift the editor away from an initial decision to accept, and the other assessing the magnitude required to shift away from an initial rejection decision. Forty-one editors completed the survey (89% response rate). In the acceptance frame, the median minimally important difference was 0.4 points on a scale of 1 to 5. Editors required a greater rating change to shift from an initial rejection decision; in the rejection frame, the median minimally important difference was 1.2 points. Within each frame, there was considerable heterogeneity: in the acceptance frame, 38% of editors did not change their decision within the maximum available range; in the rejection frame, 51% did not. To our knowledge, this is the first study to determine the minimally important difference for Likert-type ratings of research article quality, or in fact any nonclinical scientific assessment variable. Our findings may be useful for future research assessing whether changes to the peer review process produce clinically meaningful differences in editorial decisionmaking. Copyright © 2017 American College of Emergency Physicians. Published by Elsevier Inc. All rights reserved.

  7. Influence of Crack Morphology on Leak Before Break Margins

    International Nuclear Information System (INIS)

    Weilin Zang

    2007-11-01

    The purpose of the project is to evaluate the deterministic LBB-margins for different pipe systems in a Swedish PWR-plant and using different crack morphology parameters. Results: - The influence of crack morphology on Leak Before Break (LBB) margins is studied. The subject of the report is a number of LBB-submittals to SKI where deterministic LBB-margins are reported. These submittals typically uses a surface roughness of 0.0762 mm (300 microinch) and number of turns equal to zero and an in-house code for the leak rate evaluations. The present report has shown that these conditions give the largest LBB-margins both in terms of the quotient between the critical crack length and the leakage crack size and for the leak rate margin. - Crack morphology parameters have a strong influence on the leak rate evaluations. Using the SQUIRT code and more recent recommendations for crack morphology parameters, it is shown that in many cases the evaluated margins, using 1 gpm as the reference leak rate detection limit, are below the safety factor of 2 on crack size and 10 on leak rate, which is generally required for LBB approval. - The effect of including weld residual stresses on the LBB margins is also investigated. It is shown that for the two examples studied, weld residual stresses were important for the small diameter thin wall pipe whereas it was negligible for the large diameter thick wall pipe which had a self-balanced weld residual stress distribution

  8. Pumping and leak detection system of the HL-2A

    International Nuclear Information System (INIS)

    Cao Zeng; Xu Yunxian; Fu Weidong

    2001-01-01

    The pumping system is a combination of 8 turbomolecular pumps with three stages pumping for HL-2A vacuum vessel, a total effective pumping speed at the vessel of 12 m 3 ·s -1 for nitrogen. The leak detection of element and vessel is performed with inspiration, case of leak detection and two mass spectrometry. The total leak rate of vessel is bellow 1 x 10 -5 Pa ·m 3 ·s -1 . The base pressure is 1 x 10 -5 Pa

  9. Steam and sodium leak simulation in a fluidized-bed steam generator

    International Nuclear Information System (INIS)

    Vaux, W.G.; Keeton, A.R.; Keairns, D.L.

    1977-01-01

    A fluidized-bed steam generator for the liquid metal fast breeder reactor enhances plant availability and minimizes the probability of a water/sodium reaction. An experimental test program was conceived to assess design criteria and fluidized-bed operation under conditions of water, steam, and sodium leaks. Sodium, steam, and water were leaked into helium-fluidized beds of metal and ceramic particles at 900 F. Test results show the effects of leaks on the heat transfer coefficient, quality of fluidization, leak detection, and cleanup procedures

  10. FUZZY INFERENCE BASED LEAK ESTIMATION IN WATER PIPELINES SYSTEM

    Directory of Open Access Journals (Sweden)

    N. Lavanya

    2015-01-01

    Full Text Available Pipeline networks are the most widely used mode for transporting fluids and gases around the world. Leakage in this pipeline causes harmful effects when the flowing fluid/gas is hazardous. Hence the detection of leak becomes essential to avoid/minimize such undesirable effects. This paper presents the leak detection by spectral analysis methods in a laboratory pipeline system. Transient in the pressure signal in the pipeline is created by opening and closing the exit valve. These pressure variations are captured and power spectrum is obtained by using Fast Fourier Transform (FFT method and Filter Diagonalization Method (FDM. The leaks at various positions are simulated and located using these methods and the results are compared. In order to determine the quantity of leak a 2 × 1 fuzzy inference system is created using the upstream and downstream pressure as input and the leak size as the output. Thus a complete leak detection, localization and quantification are done by using only the pressure variations in the pipeline.

  11. Study of the characteristics of water into sodium leak acoustic noise in LMR steam generator

    International Nuclear Information System (INIS)

    Kim, Tae Joon; Jeong, Kyung Chai; Jeong, Ji Young; Hur, Seop; Nam, Ho Yun

    2005-01-01

    A successful time for detecting a water/steam leak into sodium in the LMR SG (steam generator) at an early phase of a leak origin depends on the fast response and sensitivity of a leak detection system. It is considered, that the acoustic system is intended for a fast detecting of a water/steam into sodium leak of an intermediate flow rate, 1∼10 g/s. This intention of an acoustic system is stipulated by a key impossibility of a fast detecting of an intermediate leak by the present nominal systems on measuring the hydrogen in the sodium and in the cover gas concentration generated at a leak. During the self-wastage of a water/steam into sodium leak in a particular instant, it is usual in 30∼40 minutes from the moment of a leak origin, there is a modification of a leak flow out regime from bubble regime to the steam jet outflow. This evolution occurs as a jump function of the self-wastage of a leak and is escorted by an increase of a leak noise power and qualitative change of a leak noise spectrum. Subject of this study is by means of two experiments, one is an acoustic leak noise analysis of the water into sodium leak results in no damage to the LMR SG tube bundle, and another is for prediction of the frequency band under a high outflow leak condition. We experimented with the Argon gas injection considered with the phenomena of secondary leaks in real

  12. Estimating particle release through gas leaks in dry powder shipping containers

    International Nuclear Information System (INIS)

    Schwendiman, L.C.

    1977-06-01

    Information is presented from which an estimate can be made of the release of plutonium oxide from shipping containers. The leak diameter is estimated from gas leak tests of the container and an estimate is made of gas leak rate as a function of pressure over the time of interest in the accident. These calculations are limited in accuracy because of assumptions regarding leak geometry and the basic formulations of hydrodynamic flow for the assumed conditions. Sonic flow is assumed to be the limiting gas flow rate. Particles leaking from the air space above the powder will be limited by the low availability of particles due to rapid settling, the very limited driving force (pressure buildup) during the first minute, and the deposition in the leak channel. Equations are given to estimate deposition losses. Leaks of particles occurring below the level of the bulk powder will be limited by mechanical interference when leaks are of dimension smaller than particle sizes present. Some limiting cases can be calculated. When the leak dimension is large compared to the particle sizes present, maximum particle releases can be estimated, but will be very conservative. Further theoretical and experimental studies are needed to better define the hydrodynamics of gas flow in leaks of the size being considered, and to establish particle transport rates through known geometry leak paths

  13. Experiments on leak-selfwastage and leak-propagation

    International Nuclear Information System (INIS)

    Voss, J.; Vagt, P.; Westenbrugge, J.K. van; Joziasse, J.

    1984-01-01

    During the last years a considerable number of selfwastage experiments with small leaks of different shape and size and for different ferritic materials (2 1/4% Cr - and 12% Cr-steel) were performed by TNO and by INTERATOM, using several sodium test facilities. Many fabrication-methods of artificial micro-leaks were applied and examined. Selfplugging-, selfwastage- and reopening-effects were observed and evaluated during different time periods and under various test conditions. The main results will be discussed. Concerning the leak propagation program of INTERATOM, the first series of experiments was carried out this year. A short status report and some first results will be given. (author)

  14. Clinical Factors and Postoperative Impact of Bile Leak After Liver Resection.

    Science.gov (United States)

    Martin, Allison N; Narayanan, Sowmya; Turrentine, Florence E; Bauer, Todd W; Adams, Reid B; Stukenborg, George J; Zaydfudim, Victor M

    2018-04-01

    Despite technical advances, bile leak remains a significant complication after hepatectomy. The current study uses a targeted multi-institutional dataset to characterize perioperative factors that are associated with bile leakage after hepatectomy to better understand the impact of bile leak on morbidity and mortality. Adult patients in the 2014-2015 ACS NSQIP targeted hepatectomy dataset were linked to the ACS NSQIP PUF dataset. Bivariable and multivariable regression analyses were used to assess the associations between clinical factors and post-hepatectomy bile leak. Of 6859 patients, 530 (7.7%) had a postoperative bile leak. Proportion of bile leaks was significantly greater in patients after major compared to minor hepatectomy (12.6 vs. 5.1%, p leak was significantly greater in patients after major hepatectomy who had concomitant enterohepatic reconstruction (31.8 vs. 10.1%, p leaks (6.0 vs. 1.7%, p leak was independently associated with increased risk of postoperative morbidity (OR = 4.55; 95% CI 3.72-5.56; p leak was not independently associated with increased risk of postoperative mortality (p = 0.262). Major hepatectomy and enterohepatic biliary reconstruction are associated with significantly greater rates of bile leak after liver resection. Bile leak is independently associated with significant postoperative morbidity. Mitigation of bile leak is critical in reducing morbidity and mortality after liver resection.

  15. Bile Duct Leaks from the Intrahepatic Biliary Tree: A Review of Its Etiology, Incidence, and Management

    Directory of Open Access Journals (Sweden)

    Sorabh Kapoor

    2012-01-01

    Full Text Available Bile leaks from the intrahepatic biliary tree are an important cause of morbidity following hepatic surgery and trauma. Despite reduction in mortality for hepatic surgery in the last 2 decades, bile leaks rates have not changed significantly. In addition to posted operative bile leaks, leaks may occur following drainage of liver abscess and tumor ablation. Most bile leaks from the intrahepatic biliary tree are transient and managed conservatively by drainage alone or endoscopic biliary decompression. Selected cases may require reoperation and enteric drainage or liver resection for management.

  16. Six-year success rates of occlusal amalgam and glass-ionomer restorations placed using three minimal intervention approaches.

    NARCIS (Netherlands)

    Mandari, G.J.; Frencken, J.E.F.M.; Hof, M.A. van 't

    2003-01-01

    The present randomised clinical trial was aimed at comparing three minimally invasive restorative treatment approaches for managing dental caries in occlusal surfaces using a non-gamma-2 amalgam and a low-viscosity glass-ionomer as the restorative material. The treatment approaches tested in

  17. Autologous Blood Pleurodesis In Patients With Persistent Air Leaks

    Directory of Open Access Journals (Sweden)

    Agkajanzadeh M

    2003-10-01

    Full Text Available Persistent air leaks occur after Spontaneous pneumothorax both primary and secondary, and after lungs trauma and lung surgeries are sever problems encountered chest surgeons with. Persistent air leak causes longer patients hospitalization."nMaterials and Methods: We used autologous blood pleurodesis in patients with persistent air leak for 30patients with more than 8 days air leaks, during a three years period 1377-1380 (1999-2002."nResults: The patients had 19 years up to 70 years old. Eight patients had thoracotomy and lobectomy and /or segmentectomies 6 with primary pneumothorax, 10 with secondary pneumothorax, and four with penetrated or blunt thoracic traumas. Blood was obtained from femoral or brachial veins and 70-150 mis. Injected in chest tubes. Chest bottle was first lied 80cm higher than body levels. After 24 hours repositioned in normal levels, and patients were supervised. Via chest tube we injected blood 70-100ml.for young patients, and 100-150 ml for older patients into intra pleural space. There were no clamped chest tubes. There were no pain, respiratory distress, fever, or cough in pleurodesized patients. The only patient's complaint was local pain in femoral vein or brachial vein because blood sampling and blood obtaining, although there was no local visible complication as hematoma or bleeding. After 48 hours in 24 patients air leak ceased. In six patients because persistent air leak autologous blood pleurodesis repeated, two patients after 48hours"nair leak ceased, remaining four patients underwent for thoracotomies, success rate"nwas 86.6%."nConclusion: According above success rate we suggest autologous blood pleurodesis in patients with persistent air leak is a reliable, effective, and no complicated procedure for persistent air leaks.

  18. Identification of sewage leaks by active remote-sensing methods

    Science.gov (United States)

    Goldshleger, Naftaly; Basson, Uri

    2016-04-01

    The increasing length of sewage pipelines, and concomitant risk of leaks due to urban and industrial growth and development is exposing the surrounding land to contamination risk and environmental harm. It is therefore important to locate such leaks in a timely manner, to minimize the damage. Advances in active remote sensing Ground Penetrating Radar (GPR) and Frequency Domain Electromagnetic (FDEM) technologies was used to identify leaking potentially responsible for pollution and to identify minor spills before they cause widespread damage. This study focused on the development of these electromagnetic methods to replace conventional acoustic methods for the identification of leaks along sewage pipes. Electromagnetic methods provide an additional advantage in that they allow mapping of the fluid-transport system in the subsurface. Leak-detection systems using GPR and FDEM are not limited to large amounts of water, but enable detecting leaks of tens of liters per hour, because they can locate increases in environmental moisture content of only a few percentage along the pipes. The importance and uniqueness of this research lies in the development of practical tools to provide a snapshot and monitoring of the spatial changes in soil moisture content up to depths of about 3-4 m, in open and paved areas, at relatively low cost, in real time or close to real time. Spatial measurements performed using GPR and FDEM systems allow monitoring many tens of thousands of measurement points per hectare, thus providing a picture of the spatial situation along pipelines and the surrounding. The main purpose of this study was to develop a method for detecting sewage leaks using the above-proposed geophysical methods, since their contaminants can severely affect public health. We focused on identifying, locating and characterizing such leaks in sewage pipes in residential and industrial areas.

  19. Water leak detection in steam generator of SUPER PHENIX

    International Nuclear Information System (INIS)

    Brunet, M.; Garnaud, P.; Ghaleb, D.; Kong, N.

    1988-01-01

    With the intent of detecting water leaks inside steam generators, we developed a third system, called acoustic detector, to complement hydrogen detectors and rupture disks (burst disks). The role of the acoustic system is to enable rapid intervention in the event of a leak growing rapidly which could rupture neighbouring tubes. In such a case, the detectable flow rate of the leak varies from a few tens of g/s to a few hundred g/s. At the SUPER PHENIX, three teams work in [20-100 kHz] and CEA/STA* [50-300 kHz]. The simulation of water leaks in the steam generator by the argon injections performed to date at 50% of the rated power has shown promising results. An anomaly in the evolution of the background noise at more than 50% loading of one of the two instrumented steam generators would make difficult any extrapolation to full power behaviour. (author)

  20. Measurement of Submerged Oil/Gas Leaks using ROV Video

    Science.gov (United States)

    Shaffer, Franklin; de Vera, Giorgio; Lee, Kenneth; Savas, Ömer

    2013-11-01

    Drilling for oil or gas in the Gulf of Mexico is increasing rapidly at depths up to three miles. The National Commission on the Deepwater Horizon Oil Leak concluded that inaccurate estimates of the leak rate from the Deepwater Horizon caused an inadequate response and attempts to cap the leak to fail. The first response to a submerged oil/gas leak will be to send a Remotely Operated Vehicle (ROV) down to view the leak. During the response to the Deepwater Horizon crisis, the authors Savas and Shaffer were members of the Flow Rate Technical Group's Plume Team who used ROV video to develop the FRTG's first official estimates of the oil leak rate. Savas and Shaffer developed an approach using the larger, faster jet features (e.g., turbulent eddies, vortices, entrained particles) in the near-field developing zone to measure discharge rates. The authors have since used the Berkeley Tow Tank to test this approach on submerged dye-colored water jets and compressed air jets. Image Correlation Velocimetry has been applied to measure the velocity of visible features. Results from tests in the Berkeley Tow Tank and submerged oil jets in the OHMSETT facility will be presented.

  1. Tube leak detector

    International Nuclear Information System (INIS)

    Morita, Bunji; Takamura, Koichi; Matsuda, Shigehiro; Kiyosawa, Shun-ichi; Asami, Toru; Yamada, Hiroshi; Naruse, Shin-ichi.

    1995-01-01

    The device of the present invention detects occurrence of leakage in a steam generator, a steam heating tube, or a heat exchanger of a nuclear power plant. Namely, an vibration sensor is disposed at the rear end of a rod-like supersonic resonance member. A node portion for the vibrations of the resonance member is held by a holding member and attached to a wall surface of a can such as a boiler. With such a constitution, the resonance member is resonated by supersonic waves generated upon leakage of the tube. The vibrations are measured by the vibration sensor at the rear end. Presence of leakage is detected by utilizing one or more of resonance frequencies. Since the device adopts a resonance phenomenon, a conduction efficiency of the vibrations is high, thereby enabling to detect leakage at high sensitivity. In addition, the supersonic wave resonance member has its top end directly protruded into a pressure vessel such as a boiler by using a metal or a ceramic which is excellent in heat and pressure resistance. Accordingly, the sound of leak can be detected efficiently. (I.S.)

  2. Liquid to gas leak ratios with liquid nitrogen and liquid helium

    International Nuclear Information System (INIS)

    Batzer, T.H.; Call, W.R.

    1985-01-01

    To predict the leak rates of liquid helium and liquid nitrogen containers at operating conditions we need to know how small leaks (10 -8 to 10 -5 atm-cm 3 air/s), measured at standard conditions, behave when flooded with these cryogens. Two small leaks were measured at ambient conditions (approx.750 Torr and 295 K), at the normal boiling points of LN 2 and LHe, and at elevated pressures above the liquids. The ratios of the leak rates of the liquids at ambient pressure to the gases (G) at ambient pressure and room temperature were: GN 2 (1), LN 2 (18), GHe(1), and LHe(172). The leak rate ratio of LN 2 at elevated pressure was linear with pressure. The leak rate ratio of LHe at elevated pressure was also linear with pressure

  3. Liquid to gas leak ratios with liquid nitrogen and liquid helium

    International Nuclear Information System (INIS)

    Batzer, T.H.; Call, W.R.

    1985-01-01

    To predict the leak rates of liquid helium and liquid nitrogen containers at operating conditions we need to know how small leaks (10 -8 to 10 -5 atm-cm 3 air/s), measured at standard conditions, behave when flooded with these cryogens. Two small leaks were measured at ambient conditions (about 750 Torr and 295 K), at the normal boiling points of LN 2 and LHe, and at elevated pressures above the liquids. The ratios of the leak rates of the liquids at ambient pressure to the gases at ambient pressure and room temperature are presented. The leak rate ratio of LN 2 at elevated pressure was linear with pressure. The leak rate ratio of LHe at elevated pressure was also linear with pressure

  4. An integrated leak detection system for the ALMR steam generator

    International Nuclear Information System (INIS)

    Dayal, Y.; Gaubatz, D.C.; Wong, K.K.; Greene, D.A.

    1995-01-01

    The steam generator (SG) of the Advanced Liquid Metal Reactor (ALMR) system serves as a heat exchanger between the shell side secondary loop hot liquid sodium and the tube side water/steam mixture. A leak in the tube will result in the injection of the higher pressure water/steam into the sodium and cause an exothermic sodium-water reaction. An initial small leak (less than 1 gm/sec) can escalate into an intermediate size leak in a relatively short time by self enlargement of the original flaw and by initiating leaks in neighboring tubes. If not stopped, complete rupture of one or more tubes can cause injection rates of thousands of gm/sec and result in the over pressurization of the secondary loop rupture disk and dumping of the sodium to relieve pressure. The down time associated with severe sodium-water reaction damage has great adverse economic consequence. An integrated leak detection system (ILDS) has been developed which utilizes both chemical and acoustic sensors for improved leak detection. The system provides SG leak status to the reactor operator and is reliable enough to trigger automatic control action to protect the SG. The ILDS chemical subsystem uses conventional in-sodium and cover gas hydrogen detectors and incorporates knowledge based effects due to process parameters for improved reliability. The ILDS acoustic subsystem uses an array of acoustic sensors and incorporates acoustic beamforming technology for highly reliable and accurate leak identification and location. The new ILDS combines the small leak detection capability of the chemical system with the reliability and rapid detection/location capability of the acoustic system to provide a significantly improved level of protection for the SG over a wide range of operation conditions. (author)

  5. Development of leak detector by radiation. 2

    International Nuclear Information System (INIS)

    Suzuki, Takashi; Okano, Yasuhiro; Chisaka, Haruo

    1997-01-01

    Leak detector by radiation has been developed by cooperative research between Water Authority and us. In his fiscal year, the most suitable arrangement of detector system was simulated by Monte Carlo method. The first, the experimental values were compared with the results of simulation. The second, calculation was carried out by changing the quality of reflective materials and distance between radiation source and detector. The simulation results were agreed with the experimental results. On the basis of the rate of presence of leak, the most suitable arrangement of detector system was obtained under the conditions that both radiation source and detector covered with graphite or iron of 5 cm thickness and separated each other 3 cm apart. However, by comparing FOM (figure of merit), the suitable arrangement was that radiation source and detector adjoined each other and covered by graphite or iron of 20 cm thickness. (S.Y.)

  6. Leak monitoring method for a reactor container

    International Nuclear Information System (INIS)

    Uehara, Toshio.

    1987-01-01

    Purpose: To confirm leakages from a container upon nuclear reactor operation. Method: Leakages from a nuclear reactor container has been prevented by lowering the inner pressure of the container relative to the external pressure. In the conventional method of calculating the leakage by applying an inner pressure to the container and measuring the pressure change, etc. after the elapse of a pre-determined time, the measurement has to be conducted at periodical inspection when the nuclear reactor is shut-down. In view of the above, the leak test is conducted in the present invention by applying a slight inner pressure to the inside of the reactor container by supplying gases from a gas supply system and detecting the flow rate of the gases in the gas supply system while maintaining the slight inner pressure constant by controlling the supply and discharge of the gases. By applying such a inner pressure as causing no effect to the reactor operation, it is possible to monitor the leaks during operation and to detect the flow rate value surely and continuously if the leak is resulted. (Kamimura, M.)

  7. Evaluation of a leaking crack in an irradiated CANDU pressure tube

    International Nuclear Information System (INIS)

    Coleman, C.E.; Simpson, L.A.

    1988-06-01

    Leak-before-break is used in CANDU reactors as part of the defence against rupture of the pressure tubes. Two important features of this technique are the action time available for detection of a leaking crack and the size of the leak allowing crack location. Support for continued reliance on leak-before-break is being obtained from experiments, on irradiated Zr-2.5 Nb pressure tubes attached to their end fittings, that simulate the behaviour of a leaking crack in a reactor. At reactor operating temperatures leaking cracks grow more slowly than dry cracks in the laboratory because they are cooled when pressurised water flashes to steam on their surface. These cracks remain stable till they are at least 70 mm long. From the results of these experiments the action time is at least 100 h. The leak rate increases rapidly when a through-wall crack extends a small amount, thus greatly assisting with crack location

  8. Differential Impact of Anastomotic Leak in Patients With Stage IV Colonic or Rectal Cancer

    DEFF Research Database (Denmark)

    Nordholm-Carstensen, Andreas; Rolff, Hans Christian; Krarup, Peter-Martin

    2017-01-01

    BACKGROUND: Anastomotic leak has a negative impact on the prognosis of patients who undergo colorectal cancer resection. However, data on anastomotic leak are limited for stage IV colorectal cancers. OBJECTIVE: The purpose of this study was to investigate the impact of anastomotic leak on survival....... PATIENTS: Patients who were diagnosed with stage IV colorectal cancer between 2009 and 2013 and underwent elective resection of their primary tumors were included. MAIN OUTCOME MEASURES: The primary outcome was all-cause mortality depending on the occurrence of anastomotic leak. Secondary outcomes were...... the administration of and time to adjuvant chemotherapy, metastasectomy rate, and risk factors for leak. RESULTS: Of the 774 patients with stage IV colorectal cancer who were included, 71 (9.2%) developed anastomotic leaks. Anastomotic leak had a significant impact on the long-term survival of patients with colon...

  9. Novel Methods of Hydrogen Leak Detection

    International Nuclear Information System (INIS)

    Pushpinder S Puri

    2006-01-01

    For hydrogen to become a consumer fuel for automotive and domestic power generation, safety is paramount. Today's hydrogen systems are built with inherent safety measures and multiple levels of protection. However, human senses, in particular, the sense of smell, is considered the ultimate safeguards against leaks. Since hydrogen is an odorless gas, use of odorants to detect leaks, as is done in case of natural gas, is obvious solution. The odorants required for hydrogen used in fuel cells have a unique requirement which must be met. This is because almost all of the commercial odorants used in gas leak detection contain sulfur which acts as poison for the catalysts used in hydrogen based fuel cells, most specifically for the PEM (polymer electrolyte membrane or proton exchange membrane) fuel cells. A possible solution to this problem is to use non-sulfur containing odorants. Chemical compounds based on mixtures of acrylic acid and nitrogen compounds have been adopted to achieve a sulfur-free odorization of a gas. It is, therefore, desired to have a method and system for hydrogen leak detection using odorant which can incorporate a uniform concentration of odorant in the hydrogen gas, when odorants are mixed in the hydrogen storage or delivery means. It is also desired to develop methods where the odorant is not added to the bulk hydrogen, keeping it free of the odorization additives. A series of novel solutions are proposed which address the issues raised above. These solutions are divided into three categories as follows: 1. Methods incorporating an odorant in the path of hydrogen leak as opposed to adding it to the hydrogen gas. 2. Methods where odorants are generated in-situ by chemical reaction with the leaking hydrogen 3. Methods of dispensing and storing odorants in high pressure hydrogen gas which release odorants to the gas at a uniform and predetermined rates. Use of one or more of the methods described here in conjunction with appropriate engineering

  10. Mapping urban pipeline leaks: Methane leaks across Boston

    International Nuclear Information System (INIS)

    Phillips, Nathan G.; Ackley, Robert; Crosson, Eric R.; Down, Adrian; Hutyra, Lucy R.; Brondfield, Max; Karr, Jonathan D.; Zhao Kaiguang; Jackson, Robert B.

    2013-01-01

    Natural gas is the largest source of anthropogenic emissions of methane (CH 4 ) in the United States. To assess pipeline emissions across a major city, we mapped CH 4 leaks across all 785 road miles in the city of Boston using a cavity-ring-down mobile CH 4 analyzer. We identified 3356 CH 4 leaks with concentrations exceeding up to 15 times the global background level. Separately, we measured δ 13 CH 4 isotopic signatures from a subset of these leaks. The δ 13 CH 4 signatures (mean = −42.8‰ ± 1.3‰ s.e.; n = 32) strongly indicate a fossil fuel source rather than a biogenic source for most of the leaks; natural gas sampled across the city had average δ 13 CH 4 values of −36.8‰ (±0.7‰ s.e., n = 10), whereas CH 4 collected from landfill sites, wetlands, and sewer systems had δ 13 CH 4 signatures ∼20‰ lighter (μ = −57.8‰, ±1.6‰ s.e., n = 8). Repairing leaky natural gas distribution systems will reduce greenhouse gas emissions, increase consumer health and safety, and save money. Highlights: ► We mapped 3356 methane leaks in Boston. ► Methane leaks in Boston carry an isotopic signature of pipeline natural gas. ► Replacing failing gas pipelines will provide safety, environmental, and economic benefits. - We identified 3356 methane leaks in Boston, with isotopic characteristics consistent with pipeline natural gas.

  11. Evaluation of pH, buffering capacity, viscosity and flow rate levels of saliva in caries-free, minimal caries and nursing caries children: An in vivo study

    Directory of Open Access Journals (Sweden)

    Dwitha Animireddy

    2014-01-01

    Full Text Available Background and Aim: The present study was undertaken to evaluate the pH, buffering capacity, viscosity and flow rate of saliva in caries free, minimal caries and nursing caries children and to evaluate the relationship of these on the caries activity of children. Materials and Methods: A total of 75 school children of age group between 4 and 12 years were selected and divided into three equal groups: Group I, Group II and Group III, consisting of 25 subjects each. Group I included caries-free subjects, Group II included subjects with minimal caries and Group III included subjects with nursing caries. Saliva samples were collected from all subjects and were estimated for flow rate, pH, buffering capacity and viscosity. Results: There was a significant decrease in the mean salivary flow rate, salivary ph and salivary buffer capacity and a significant increase in the salivary viscosity among caries-free subjects, subjects with minimal caries and subjects with nursing caries. Conclusion: The physicochemical properties of saliva, such as salivary flow rate, pH, buffering capacity and viscosity, has a relation with caries activity in children and act as markers of caries activity.

  12. Evaluation of methods for leak detection in reactor primary systems and NDE of cast stainless steel

    International Nuclear Information System (INIS)

    Kupperman, D.S.; Claytor, T.N.; Prine, D.W.; Mathieson, T.A.

    1984-01-01

    Six cracks, including two field-induced IGSCC specimens and two thermal-fatigue cracks, have been installed in a laboratory acoustic leak detection facility. The IGSCC specimens produce stronger acoustic signals than the thermal-fatigue cracks at equivalent leak rates. Despite significant differences in crack geometry, the acoustic signals from the two IGSCC specimens, tested at the same leak rate, are virtually identical in the frequency range from 200 to 400 kHz. Thus, the quantitative correlations between the acoustic signals and leak rate in the 300 to 400 kHz band are very similar for the two IGSCC specimens. Also, acoustic background data have been acquired during a hot functional sensitivity of acoustic leak detection techniques. In addition, cross-correlation techniques have been successfully used in the laboratory to locate the source of an electronically simulated leak signal

  13. Acoustic Leak Detection Testing Using KAERI Sodium-Water Reaction Signals for a SFR Steam Generator

    International Nuclear Information System (INIS)

    Kim, Tae-Joon; Jeong, Ji-Young; Kim, Jong-Man; Kim, Byung-Ho; Hahn, Do-Hee; Yugay, Valeriy S.

    2009-01-01

    The results of an experimental study of water in a sodium leak noise spectrum formation at 0.004-0.54 g/sec, various rates of water into a sodium leak, smaller than 1.0 g/sec, are presented. We focused on studying a micro leak detection with an increasing rate of water into sodium. On the basis of the experimental leak noise data manufactured in KAERI the simple dependency of an acoustic signal level from the rate of a micro and small leak at different frequency bands is presented to understand the principal analysis for the development of an acoustic leak detection methodology used in a K- 600 steam generator

  14. Epidural block and neostigmine cause anastomosis leak

    Directory of Open Access Journals (Sweden)

    Ataro G

    2016-05-01

    Full Text Available Getu Ataro Department of Anesthesia, Jimma University, Jimma, EthiopiaI read the article by Phillips entitled, “Reducing gastrointestinal anastomotic leak rates: review of challenges and solutions”, published in the journal of Open Access Surgery with enthusiasm and found it crucial for perioperative management of patients with gastrointestinal (GI surgery, particularly anastomosis. I appreciate the author’s exhaustive search of literature and discussion with some limitation on review basics like methodology, which may affect the reliability of the review findings. The effects of risk factors for anastomosis leak, such as malnutrition, smoking, steroid use, bowel preparation, chemotherapy, duration of surgery, use of pressors, intravenous fluid administration, blood transfusion, and surgical anastomotic technique, were well discussed.1 However, from anesthesia perspective, there are some other well-studied risk factors that can affect healing of anastomosis wound and cause anastomosis leak. Among others, the effect of neostigmine and epidural block has been reported in many studies since half a century ago. View the original paper by Phillips

  15. Some considerations in standard gas leak designs and their applications to computer control systems

    International Nuclear Information System (INIS)

    Winkelman, C.R.; Wedel, T.A.

    The primary difficulty with flow rate measurements below 10 -10 standard cubic centimeters per second (std. cc/sec) is that there are no commercially available standards. The requirements, however, dictate that the problem of design and construction of a qualifiable standard in the ultra-sensitive range had to be solved. There are a number of leak types which were considered: capillary leaks, orifice leaks, and the pore type leaks, among others. The capillary leak was not used because of the cracking or sorting effects that are common to this type leak. For example, a gas blend flowing through a capillary leak will result in the lighter gases passing through the leak first. The difficulty of fabricating the proper hole size in relation to the flow rate requirements ruled out the orifice type leak. The selected choice was the pore type leak which utilizes the basic concept of a stainless steel knife edge driven into a fixed section composed of stainless steel with a gold overlay and maintained under force

  16. A multicenter study of routine versus selective intraoperative leak testing for sleeve gastrectomy.

    Science.gov (United States)

    Bingham, Jason; Kaufman, Jedediah; Hata, Kai; Dickerson, James; Beekley, Alec; Wisbach, Gordon; Swann, Jacob; Ahnfeldt, Eric; Hawkins, Devon; Choi, Yong; Lim, Robert; Martin, Matthew

    2017-09-01

    Staple line leaks after sleeve gastrectomy are dreaded complications. Many surgeons routinely perform an intraoperative leak test (IOLT) despite little evidence to validate the reliability, clinical benefit, and safety of this procedure. To determine the efficacy of IOLT and if routine use has any benefit over selective use. Eight teaching hospitals, including private, university, and military facilities. A multicenter, retrospective analysis over a 5-year period. The efficacy of the IOLT for identifying unsuspected staple line defects and for predicting postoperative leaks was evaluated. An anonymous survey was also collected reflecting surgeons' practices and beliefs regarding IOLT. From January 2010 through December 2014, 4284 patients underwent sleeve gastrectomy. Of these, 37 patients (.9%) developed a postoperative leak, and 2376 patients (55%) received an IOLT. Only 2 patients (0.08%) had a positive finding. Subsequently, 21 patients with a negative IOLT developed a leak. IOLT demonstrated a sensitivity of only 8.7%. There was a nonsignificant trend toward increased leak rates when an IOLT was performed versus when IOLT was not performed. Leak rates were not statistically different between centers that routinely perform IOLT versus those that selectively perform IOLT. Routine IOLT had very poor sensitivity and was negative in 91% of patients who later developed postoperative leaks. The use of IOLT was not associated with a decrease in the incidence of postoperative leaks, and routine IOLT had no benefit over selective leak testing. IOLT should not be used as a quality indicator or "best practice" for bariatric surgery. Published by Elsevier Inc.

  17. Noble Gas Leak Detector for Use in the SNS Neutron Electric Dipole Moment Experiment

    Science.gov (United States)

    Barrow, Chad; Huffman, Paul; Leung, Kent; Korobkina, Ekaterina; White, Christian; nEDM Collaboration Collaboration

    2017-09-01

    Common practice for leak-checking high vacuum systems uses helium as the probing gas. However, helium may permeate some materials at room temperature, making leak characterization difficult. The experiment to find a permanent electric dipole moment of the neutron (nEDM), to be conducted at Oak Ridge National Laboratories, will employ a large volume of liquid helium housed by such a helium-permeable composite material. It is desirable to construct a leak detector that can employ alternative test gases. The purpose of this experiment is to create a leak detector that can quantify the argon gas flux in a high vacuum environment and interpret this flux as a leak-rate. This apparatus will be used to check the nEDM volumes for leaks at room temperature before cooling down to cryogenic temperatures. Our leak detector uses a residual gas analyzer and a vacuum pumping station to characterize the gas present in an evacuated volume. The introduction of argon gas into the system is interpreted as a leak-rate into the volume. The device has been calibrated with NIST certified calibrated leaks and the machine's sensitivity has been calculated using background gas analysis. As a result of the device construction and software programming, we are able to leak-check composite and polyamide volumes This work was supported in part by the US Department of Energy under Grant No. DE-FG02-97ER41042.

  18. Should measurement of maximum urinary flow rate and residual urine volume be a part of a "minimal care" assessment programme in female incontinence?

    DEFF Research Database (Denmark)

    Sander, Pia; Mouritsen, L; Andersen, J Thorup

    2002-01-01

    OBJECTIVE: The aim of this study was to evaluate the value of routine measurements of urinary flow rate and residual urine volume as a part of a "minimal care" assessment programme for women with urinary incontinence in detecting clinical significant bladder emptying problems. MATERIAL AND METHODS....... Twenty-six per cent had a maximum flow rate less than 15 ml/s, but only 4% at a voided volume > or =200 ml. Residual urine more than 149 ml was found in 6%. Two women had chronic retention with overflow incontinence. Both had typical symptoms with continuous leakage, stranguria and chronic cystitis...

  19. Mitigated Transfer Line Leaks that Result in Surface Pools and Spray Leaks into Pits

    Energy Technology Data Exchange (ETDEWEB)

    HEY, B.E.

    1999-12-07

    This analysis provides radiological and toxicological consequence calculations for postulated mitigated leaks during transfers of six waste compositions. Leaks in Cleanout Boxes equipped with supplemental covers and leaks in pits are analyzed.

  20. Mitigated Transfer Line Leaks that Result in Surface Pools and Spray Leaks into Pits

    International Nuclear Information System (INIS)

    HEY, B.E.

    1999-01-01

    This analysis provides radiological and toxicological consequence calculations for postulated mitigated leaks during transfers of six waste compositions. Leaks in Cleanout Boxes equipped with supplemental covers and leaks in pits are analyzed

  1. Gas Leak Detection by Dilution of Atmospheric Oxygen

    Directory of Open Access Journals (Sweden)

    Armin Lambrecht

    2017-12-01

    Full Text Available Gas leak detection is an important issue in infrastructure monitoring and industrial production. In this context, infrared (IR absorption spectroscopy is a major measurement method. It can be applied in an extractive or remote detection scheme. Tunable laser spectroscopy (TLS instruments are able to detect CH4 leaks with column densities below 10 ppm·m from a distance of 30 m in less than a second. However, leak detection of non-IR absorbing gases such as N2 is not possible in this manner. Due to the fact that any leaking gas displaces or dilutes the surrounding background gas, an indirect detection is still possible. It is shown by sensitive TLS measurements of the ambient background concentration of O2 that N2 leaks can be localized with extractive and standoff methods for distances below 1 m. Minimum leak rates of 0.1 mbar·L/s were determined. Flow simulations confirm that the leakage gas typically effuses in a narrow jet. The sensitivity is mainly determined by ambient flow conditions. Compared to TLS detection of CH4 at 1651 nm, the indirect method using O2 at 761 nm is experimentally found to be less sensitive by a factor of 100. However, the well-established TLS of O2 may become a universal tool for rapid leakage screening of vessels that contain unknown or inexpensive gases, such as N2.

  2. Rio Vista gas leak study: Belleaire Gas Field, California

    International Nuclear Information System (INIS)

    Wilkey, P.L.

    1992-08-01

    The Rio Vista gas leak study evaluated methods for remotely sensing gas leaks from buried pipelines and developed methods to elucidate methane transport and microbial oxidation in soils. Remote-sensing methods were evaluated by singing gas leaks along an abandoned Pacific Gas and Electric (PG ampersand E) gas field collection line in northern California and applying surface-based and airborne remote-sensing techniques in the field, including thermal imaging, laser imaging, and multispectral imagery. The remote-sensing techniques exhibited limitations in range and in their ability to correlate with ground truth data. To elucidate methane transport and microbial oxidation in soils, a study of a controlled leak permitted field testing of methods so that such processes could be monitored and evaluated. Monitoring and evaluation techniques included (1) field measurement of soil-gas concentrations, temperatures, and pressures; (2) laboratory measurement of soil physical/chemical properties and activity of methane-oxidizing microorganisms by means of field samples; and (3) development of a preliminary numerical analysis technique for combined soil-gas transport/methane oxidation. Soil-gas concentrations at various depths responded rapidly to the high rate of gas leakage. The number of methane-oxidizing microorganisms in site soils rapidly increased when the gas leak was initiated and decreased after the leak was terminated. The preliminary field, laboratory, and numerical analysis techniques tested for this study of a controlled gas leak could be successfully applied to future studies of gas leaks. Because soil-gas movement is rapid and temporally variable, the use of several complementary techniques that permit generalization of site-specific results is favored

  3. Prevention of Postoperative Bile Leak in Partial Cystectomy for Hydatid Liver Disease: Tricks of the Trade.

    Science.gov (United States)

    Peker, Kivanc Derya; Gumusoglu, Alpen Yahya; Seyit, Hakan; Kabuli, Hamit Ahmet; Salik, Aysun Erbahceci; Gonenc, Murat; Kapan, Selin; Alis, Halil

    2015-12-01

    The presence of postoperative bile leak is the major outcome measure for the assessment of operative success in partial cystectomy for hydatid liver disease. However, the optimal operative strategy to reduce the postoperative bile leak rate is yet to be defined. Medical records of patients who underwent partial cystectomy for hydatid liver disease between January 2013 and January 2015 were reviewed in this retrospective analysis. All patients were managed with a specific operative protocol. The primary outcome measure was the rate of persistent postoperative bile leak. The secondary outcome measures were the morbidity and mortality rate, and the length of hospital stay. Twenty-eight patients were included in the study. Only one patient (3.6 %) developed persistent postoperative bile leak. The overall morbidity and mortality rate was 17.8 and 0 %, respectively. The median length of hospital stay was 5 days. Aggressive preventative surgical measures have led to low persistent bile leak rates with low morbidity and mortality.

  4. Maintaining leak tightness capability of Caorso BWR containment

    International Nuclear Information System (INIS)

    Barsanti, P.; Di Palo, L.; Grimaldi, G.

    1988-01-01

    In 1987 the local leak rate test (LLRT) results of the primary containment were revised, with the following main goals: to highlight recurring problems, leading to lack of leak tightness of the primary containment; to individuate the pertinent degradation mechanisms; to assess the corrective actions already implemented and to plan further improvements, if necessary; and to optimize the preventive maintenance program on the containment, particularly the inspection frequency. All LLRTs in the past operating period, both before (as found) and after (as left) maintenance were analyzed, in terms of leakage rate and equivalent area of leak, for each penetration. Corrective actions already implemented included replacement of some valves with better quality type one, passivation of the carbon steel pipes and improvement of the pertinent surveillance procedures. Long term corrective actions, now under consideration, will include the following: more extensive passivation of pipes, carrying humid air, so that oxidation could be drastically reduced; better chemistry control in fluid systems; extensive replacement of the butterfly valves presently used; implementation of the LLRT practice, such to quantitatively measure the leakage rate, also in presence of large leak; and reduction of the time interval between periodical tests, on the basis of the results of the previous ones. Following these guidelines, future overall leakage tests would be performed in as found condition, aimed to verify the effectiveness of the entire maintenance and testing program of the primary containment and of its capability to maintain leak tightness during the time between two subsequent tests

  5. Location and repair of air leaks in the ATF vacuum vessel

    International Nuclear Information System (INIS)

    Schwenterly, S.W.; Gabbard, W.A.; Schaich, C.R.; Yarber, J.L.

    1989-01-01

    On the basis of partial pressure rate-of-rise and base pressure measurements, it was determined that the Advanced Toroidal Facility (ATF) vacuum vessel had an air leak in the low 10 -4 mbarx ell/s range. Pinpointing this leak by conventional helium leak-checking procedures was not possible, because large portions of the outside of the vessel are covered by the helical field coils and a structural shell. Various alternative leak detection schemes that were considered are summarized and their advantages and disadvantages noted. In the method ultimately employed, gum-rubber patches of various sizes ranging from 12.7 by 12.7 cm to 20.3 by 30.5 cm were positioned on the inside surfaces of the vessel and evacuated by the leak detector (LD). After roughly 5% of the surface was inspected in this way, a leak of >10 -5 mbar xL/s was discovered and localized to an area of 5 by 5 cm. Dye penetrant applied to this area disclosed three pinholes. Two small slag pockets were discovered while these points were being ground out. After these were rewelded, no further leakage could be found in the repaired area. Global leak rates measured after the machine was reevacuated indicated that this leak was about 30% of the overall leak rate. 1 ref., 5 figs., 1 tab

  6. Location and repair of air leaks in the ATF [Advanced Toroidal Facility] vacuum vessel

    International Nuclear Information System (INIS)

    Schwenterly, S.W.; Gabbard, W.A.; Schaich, C.R.; Yarber, J.L.

    1989-01-01

    On the basis of partial pressure rate-of-rise and base pressure measurements, it was determined that the Advanced Toroidal Facility (ATF) vacuum vessel had an air leak in the low 10 -4 mbar-ell/s range. Pinpointing this leak by conventional helium leak-checking procedures was not possible, because large portions of the outside of the vessel are covered by the helcial field coils and a structural shell. Various alternative leak-detection schemes that were considered are summarized and their advantages and disadvantages noted. In the method ultimately employed, gun-rubber patches of various sizes ranging from 12.7 by 12.7 cm to 20.3 by 30.5 cm were positioned on the inside surfaces of the vessel and evacuated by the leak detector (LD). After roughly 5% of the surface was inspected in this way, a leak of > 10 -5 mbar-ell/s was discovered and localized to an area of 5 by 5 cm. Dye penetrant applied to this area disclosed three pinholes. Two small slag pockets were discovered while these points were being ground out. After these were rewelded, no furthered leakage could be found in the repaired area. Global leak rates measured after the machine was reevacuated indicated that this leak was about 30% of the overall leak rate. 1 ref., 5 figs., 1 tab

  7. Transcatheter closure of paravalvular leaks using a paravalvular leak device – a prospective Polish registry

    Directory of Open Access Journals (Sweden)

    Grzegorz Smolka

    2016-05-01

    Full Text Available Introduction : Transcatheter paravalvular leak closure (TPVLC has become an established treatment option but is mostly performed with off-label use of different non-dedicated occluders. The first one specifically designed for TPVLC is the paravalvular leak device (PLD – Occlutech. Aim : We present initial short-term results of a prospective registry intended to assess the safety and efficacy of TPVLC with PLD. Material and methods : We screened patients with paravalvular leak (PVL after surgical valve replacement (SVR. Heart failure symptoms and/or hemolytic anemia were indications for TPVLC. Patients were selected according to PVL anatomy by RT 3D TEE. Only those considered appropriate for closure with a single PLD were enrolled. The procedures were performed via transvascular or transapical access using type W (waist PLDs only. Results : Thirty patients with 34 PVLs (18 aortic, 16 mitral were included. We implanted 35 PLDs with a total device success rate of 94.3% (100% for aortic, 88.2% for mitral. The procedural success rate, encompassing device success without in-hospital complications, was 94.1% (100% for aortic, 93.8% for mitral. During the follow-up period we recorded an increase of hemoglobin concentration (3.9 to 4.1 g/dl, red blood count (11.6 to 12.2 M/mm3 and functional improvement by NYHA class. Conclusions : Paravalvular leak device type W is a promising TPVLC device, but meticulous preselection of patients based on imaging of PVL anatomy is a prerequisite. A PLD should only be chosen for channels shorter than 5 mm. Size of the device should match the PVL cross-sectional area without any oversizing. Such an approach facilitates high device and procedural success rates.

  8. Leak behavior of steam generator tube-to-tubesheet joints under creep condition: Experimental study

    International Nuclear Information System (INIS)

    Bahn, Chi Bum; Majumdar, Saurin; Kasza, Ken E.; Shack, William J.

    2013-01-01

    To address concerns regarding excessive leakage from throughwall cracks in steam generator tube-to-tubesheet joints under severe accident conditions, leak rate testing was conducted using tube-to-collar joint specimens. The tube interior and the interface between tube and collar (crevice) were pressurized independently using nitrogen gas. The leak rate through the crevice was almost zero when the specimens were pressurized at ∼500 °C; this low leak rate is attributed to thermal mismatch effects preventing much leakage. The near zero leak rate was maintained until the onset of large leakage at higher temperatures. The leak rate behavior after the onset of the large leakage was not much affected by the crevice length or heat-to-heat variation of Alloy 600 tubes. This suggests that once the crevice gap opens, the creep rate of the low alloy steel collar becomes dominant. Specimens with different tube diameters behaved essentially the same way. To simulate a flawed steam generator tube in the tubesheet, the crevice region was pressurized through a hole in the tube. This simulation resulted in essentially the same behavior as those specimens whose tubes and crevices were pressurized independently. Oxidation of low alloy steel collars in air tests can increase the flow resistance, and thus tests using nitrogen gas would provide more conservative leak rate data. Highlights: ► Leak rates were measured by using tube-to-collar joint specimens under creep condition. ► Leak rate through the joint interface was almost zero at ∼500 °C due to thermal mismatch. ► The near zero leak rate was maintained until the onset of large leakage at ∼680 °C. ► The leak behavior after the onset of the large leakage was not affected by hydraulic expansion length or tube heats.

  9. Some problems of leaks in sodium-water steam generator

    International Nuclear Information System (INIS)

    Kozlov, F.A.; Sergeev, G.V.; Sednev, A.R.; Makarov, V.M.

    1976-01-01

    The paper contains data on wastage of steam generator structural materials and high-nickel alloys in the zone of water leakage into sodium as well as investigation results for self-enlargement of water leaks into sodium through defects in these materials. It is shown that the rate of material damage in the zone of sodium-water reaction and in the channel with water leaking-out decreases with increasing nickel content in steels and strongly depends on sodium temperature. The paper presents experimentally obtained dependences of leakage self-enlargement rates on sodium temperature and leakage size

  10. Bit Error-Rate Minimizing Detector for Amplify-and-Forward Relaying Systems Using Generalized Gaussian Kernel

    KAUST Repository

    Ahmed, Qasim Zeeshan

    2013-01-01

    In this letter, a new detector is proposed for amplifyand- forward (AF) relaying system when communicating with the assistance of relays. The major goal of this detector is to improve the bit error rate (BER) performance of the receiver. The probability density function is estimated with the help of kernel density technique. A generalized Gaussian kernel is proposed. This new kernel provides more flexibility and encompasses Gaussian and uniform kernels as special cases. The optimal window width of the kernel is calculated. Simulations results show that a gain of more than 1 dB can be achieved in terms of BER performance as compared to the minimum mean square error (MMSE) receiver when communicating over Rayleigh fading channels.

  11. Minimal surfaces

    CERN Document Server

    Dierkes, Ulrich; Sauvigny, Friedrich; Jakob, Ruben; Kuster, Albrecht

    2010-01-01

    Minimal Surfaces is the first volume of a three volume treatise on minimal surfaces (Grundlehren Nr. 339-341). Each volume can be read and studied independently of the others. The central theme is boundary value problems for minimal surfaces. The treatise is a substantially revised and extended version of the monograph Minimal Surfaces I, II (Grundlehren Nr. 295 & 296). The first volume begins with an exposition of basic ideas of the theory of surfaces in three-dimensional Euclidean space, followed by an introduction of minimal surfaces as stationary points of area, or equivalently

  12. Leak-before-break due to fatigue cracks in the cold leg piping system

    International Nuclear Information System (INIS)

    Mayfield, M.E.; Collier, R.P.

    1984-01-01

    This review paper presents the results of a deterministic assessment of the margin of safety against a large break in the cold leg piping system of pressurized water reactors. The paper focuses on the computation of leak rates resulting from fatigue cracks that penetrate the full wall thickness. Results are presented that illustrate the sensitivity of the leak rate to stress level, crack shape and crack orientation. Further, the leak rates for specific conditions are contrasted to detection levels, shutdown criteria, make-up capacity and the leak rate associated with final failure of the piping system. The results of these computations indicate that, in general, leaks far in excess of the present detection sensitivities would result at crack sizes well below the critical crack sizes for the upset loadings on the cold leg piping system

  13. Detecting leaks in vacuum bags

    Science.gov (United States)

    Carlstrom, E. E.

    1980-01-01

    Small leaks in vacuum bag can be readily detected by eye, using simple chemical reaction: combination of ammonia and acetic acid vapors to produce cloudy white smoke. Technique has been successfully used to test seam integrity and to identify minute pinholes in vacuum bag used in assembly of ceramic-tile heat shield for Space Shuttle Orbiter.

  14. LOCATING LEAKS WITH ACOUSTIC TECHNOLOGY

    Science.gov (United States)

    Many water distribution systems in this country are almost 100 years old. About 26 percent of piping in these systems is made of unlined cast iron or steel and is in poor condition. Many methods that locate leaks in these pipes are time-consuming, costly, disruptive to operations...

  15. Pipe Leak Detection Technology Development

    Science.gov (United States)

    The U. S. Environmental Protection Agency (EPA) has determined that one of the nation’s biggest infrastructural needs is the replacement or rehabilitation of the water distribution and transmission systems. The institution of more effective pipe leak detection technology will im...

  16. Reliability of leak detection systems in LWRs

    International Nuclear Information System (INIS)

    Kupperman, D.S.

    1986-10-01

    In this paper, NRC guidelines for leak detection will be reviewed, current practices described, potential safety-related problems discussed, and potential improvements in leak detection technology (with emphasis on acoustic methods) evaluated

  17. Stochastic Consequence Analysis for Waste Leaks

    International Nuclear Information System (INIS)

    HEY, B.E.

    2000-01-01

    This analysis evaluates the radiological consequences of potential Hanford Tank Farm waste transfer leaks. These include ex-tank leaks into structures, underneath the soil, and exposed to the atmosphere. It also includes potential misroutes, tank overflow

  18. Helium Leak Test for the PLS Storage Ring Chamber

    International Nuclear Information System (INIS)

    Choi, M. H.; Kim, H. J.; Choi, W. C.

    1993-01-01

    The storage ring vacuum system for the Pohang Light Source (PLS) has been designed to maintain the vacuum pressure of 10 1 0 Torr which requires UHV welding to have helium leak rate less than 1x10 1 0 Torr·L/sec. In order to develop new technique (PLS) welding technique), a prototype vacuum chamber has been welded by using Tungsten Inert Gas welding method and all the welded joints have been tested with a non-destructive method, so called helium leak detection, to investigate the vacuum tightness of the weld joints. The test was performed with a detection limit of 1x10 1 0 Torr·L/sec for helium and no detectable leaks were found for all the welded joints. Thus the performance of welding technique is proven to meet the criteria of helium leak rate required in the PLS Storage Ring. Both the principle and the procedure for the helium leak detection are also discussed

  19. Helium Mass Spectrometer Leak Detection: A Method to Quantify Total Measurement Uncertainty

    Science.gov (United States)

    Mather, Janice L.; Taylor, Shawn C.

    2015-01-01

    In applications where leak rates of components or systems are evaluated against a leak rate requirement, the uncertainty of the measured leak rate must be included in the reported result. However, in the helium mass spectrometer leak detection method, the sensitivity, or resolution, of the instrument is often the only component of the total measurement uncertainty noted when reporting results. To address this shortfall, a measurement uncertainty analysis method was developed that includes the leak detector unit's resolution, repeatability, hysteresis, and drift, along with the uncertainty associated with the calibration standard. In a step-wise process, the method identifies the bias and precision components of the calibration standard, the measurement correction factor (K-factor), and the leak detector unit. Together these individual contributions to error are combined and the total measurement uncertainty is determined using the root-sum-square method. It was found that the precision component contributes more to the total uncertainty than the bias component, but the bias component is not insignificant. For helium mass spectrometer leak rate tests where unit sensitivity alone is not enough, a thorough evaluation of the measurement uncertainty such as the one presented herein should be performed and reported along with the leak rate value.

  20. Simulation of leaking fuel rods

    International Nuclear Information System (INIS)

    Hozer, Z.

    2006-01-01

    The behaviour of failed fuel rods includes several complex phenomena. The cladding failure initiates the release of fission product from the fuel and in case of large defect even urania grains can be released into the coolant. In steady state conditions an equilibrium - diffusion type - release is expected. During transients the release is driven by a convective type leaching mechanism. There are very few experimental data on leaking WWER fuel rods. For this reason the activity measurements at the nuclear power plants provide very important information. The evaluation of measured data can help in the estimation of failed fuel rod characteristics and the prediction of transient release dynamics in power plant transients. The paper deals with the simulation of leaking fuel rods under steady state and transient conditions and describes the following new results: 1) A new algorithm has been developed for the simulation of leaking fuel rods under steady state conditions and the specific parameters of the model for the Paks NPP has been determined; 2) The steady state model has been applied to calculation of leaking fuel characteristics using iodine and noble gas activity measurement data; 3) A new computational method has been developed for the simulation of leaking fuel rods under transient conditions and the specific parameters for the Paks NPP has been determined; 4) The transient model has been applied to the simulation of shutdown process at the Paks NPP and for the prediction of the time and magnitude of 123 I activity peak; 5) Using Paks NPP data a conservative value has been determined for the upper limit of the 123 I release from failed fuel rods during transients

  1. Imaging review of cerebrospinal fluid leaks

    OpenAIRE

    Naga V Vemuri; Lakshmi S P Karanam; Venkatesh Manchikanti; Srinivas Dandamudi; Sampath K Puvvada; Vineet K Vemuri

    2017-01-01

    Cerebrospinal fluid (CSF) leak occurs due to a defect in the dura and skull base. Trauma remains the most common cause of CSF leak; however, a significant number of cases are iatrogenic, and result from a complication of functional endoscopic sinus surgery (FESS). Early diagnosis of CSF leak is of paramount importance to prevent life-threatening complications such as brain abscess and meningitis. Imaging plays a crucial role in the detection and characterization of CSF leaks. Three-dimensiona...

  2. Helium leak testing methods in nuclear applications

    International Nuclear Information System (INIS)

    Ahmad, Anis

    2004-01-01

    Helium mass-spectrometer leak test is the most sensitive leak test method. It gives very reliable and sensitive test results. In last few years application of helium leak testing has gained more importance due to increased public awareness of safety and environment pollution caused by number of growing chemical and other such industries. Helium leak testing is carried out and specified in most of the critical area applications like nuclear, space, chemical and petrochemical industries

  3. Calibration of a leak detection spectrometer

    International Nuclear Information System (INIS)

    Geller, R.

    1958-01-01

    This paper describes a study of the possible methods for calibrating a leak detection spectrometer, and the estimation of outputs from the leaks is considered. With this in mind the question of sensitivity of leak detection is tackled on a very general level; first the sensitivity of the isolated instrument is determined, and then the sensitivity of an instrument connected to an installation where leaks may be suspected. Finally, practical solutions are proposed. (author) [fr

  4. Anastomotic leak after colorectal resection: A population-based study of risk factors and hospital variation.

    Science.gov (United States)

    Nikolian, Vahagn C; Kamdar, Neil S; Regenbogen, Scott E; Morris, Arden M; Byrn, John C; Suwanabol, Pasithorn A; Campbell, Darrell A; Hendren, Samantha

    2017-06-01

    Anastomotic leak is a major source of morbidity in colorectal operations and has become an area of interest in performance metrics. It is unclear whether anastomotic leak is associated primarily with surgeons' technical performance or explained better by patient characteristics and institutional factors. We sought to establish if anastomotic leak could serve as a valid quality metric in colorectal operations by evaluating provider variation after adjusting for patient factors. We performed a retrospective cohort study of colorectal resection patients in the Michigan Surgical Quality Collaborative. Clinically relevant patient and operative factors were tested for association with anastomotic leak. Hierarchical logistic regression was used to derive risk-adjusted rates of anastomotic leak. Of 9,192 colorectal resections, 244 (2.7%) had a documented anastomotic leak. The incidence of anastomotic leak was 3.0% for patients with pelvic anastomoses and 2.5% for those with intra-abdominal anastomoses. Multivariable analysis showed that a greater operative duration, male sex, body mass index >30 kg/m 2 , tobacco use, chronic immunosuppressive medications, thrombocytosis (platelet count >400 × 10 9 /L), and urgent/emergency operations were independently associated with anastomotic leak (C-statistic = 0.75). After accounting for patient and procedural risk factors, 5 hospitals had a significantly greater incidence of postoperative anastomotic leak. This population-based study shows that risk factors for anastomotic leak include male sex, obesity, tobacco use, immunosuppression, thrombocytosis, greater operative duration, and urgent/emergency operation; models including these factors predict most of the variation in anastomotic leak rates. This study suggests that anastomotic leak can serve as a valid metric that can identify opportunities for quality improvement. Copyright © 2017 Elsevier Inc. All rights reserved.

  5. Fiber optic distributed chemical sensor for the real time detection of hydrocarbon fuel leaks

    Science.gov (United States)

    Mendoza, Edgar; Kempen, C.; Esterkin, Yan; Sun, Sunjian

    2015-09-01

    With the increase worldwide demand for hydrocarbon fuels and the vast development of new fuel production and delivery infrastructure installations around the world, there is a growing need for reliable hydrocarbon fuel leak detection technologies to provide safety and reduce environmental risks. Hydrocarbon leaks (gas or liquid) pose an extreme danger and need to be detected very quickly to avoid potential disasters. Gas leaks have the greatest potential for causing damage due to the explosion risk from the dispersion of gas clouds. This paper describes progress towards the development of a fast response, high sensitivity, distributed fiber optic fuel leak detection (HySense™) system based on the use of an optical fiber that uses a hydrocarbon sensitive fluorescent coating to detect the presence of fuel leaks present in close proximity along the length of the sensor fiber. The HySense™ system operates in two modes, leak detection and leak localization, and will trigger an alarm within seconds of exposure contact. The fast and accurate response of the sensor provides reliable fluid leak detection for pipelines, storage tanks, airports, pumps, and valves to detect and minimize any potential catastrophic damage.

  6. Sodium fire tests for investigating the sodium leak in Monju

    International Nuclear Information System (INIS)

    Seino, Hiroshi; Miyahara, Shinya; Miyake, Osamu; Tanabe, Hiromi

    1996-01-01

    As a part of the work for investigating the sodium leak accident which occurred in Monju on December 8, 1995, three tests, (1) sodium leak test, (2) sodium fire test-I, and (3) sodium fire test-II, were carried out at OEC/PNC. Main objectives of these tests are to confirm leak and burning behavior of sodium from the damaged thermometer, and effects of the sodium fire on integrity of the surrounding structure, etc. The main conclusions obtained from the tests are shown as below. 1) Average sodium leak rate obtained from the sodium leak test was about 50 g/sec. This was equivalent to the value estimated from level change in the sodium overflow tank in the Monju accident. 2) Observation from video cameras in the sodium fire tests revealed that in early stages of sodium leak, sodium dropped down out of the flexible tube of thermometer in drips. This dripping and burning were expanded in range as sodium splashed on the duct. 3) Though, in the sodium fire test-I, there was a decrease of about 1 mm at a thickness of the burning pan in the vicinity in just under in the leak point, there were completely no crack and failure. In the meantime, in the sodium fire test-II the six open holes were found in the floor liner. By this liner failure, the reaction between sodium and concrete might take place. At present, while the detailed evaluation on the sodium fire test-II has been mainly carried out, the investigation for clarifying the cause of the liner failure has been also carried out. (author)

  7. Leak Detection Modeling and Simulation for Oil Pipeline with Artificial Intelligence Method

    Directory of Open Access Journals (Sweden)

    Pudjo Sukarno

    2007-05-01

    Full Text Available Leak detection is always interesting research topic, where leak location and leak rate are two pipeline leaking parameters that should be determined accurately to overcome pipe leaking problems. In this research those two parameters are investigated by developing transmission pipeline model and the leak detection model which is developed using Artificial Neural Network. The mathematical approach needs actual leak data to train the leak detection model, however such data could not be obtained from oil fields. Therefore, for training purposes hypothetical data are developed using the transmission pipeline model, by applying various physical configuration of pipeline and applying oil properties correlations to estimate the value of oil density and viscosity. The various leak locations and leak rates are also represented in this model. The prediction of those two leak parameters will be completed until the total error is less than certain value of tolerance, or until iterations level is reached. To recognize the pattern, forward procedure is conducted. The application of this approach produces conclusion that for certain pipeline network configuration, the higher number of iterations will produce accurate result. The number of iterations depend on the leakage rate, the smaller leakage rate, the higher number of iterations are required. The accuracy of this approach is clearly determined by the quality of training data. Therefore, in the preparation of training data the results of pressure drop calculations should be validated by the real measurement of pressure drop along the pipeline. For the accuracy purposes, there are possibility to change the pressure drop and fluid properties correlations, to get the better results. The results of this research are expected to give real contribution for giving an early detection of oil-spill in oil fields.

  8. Characterization of leaks from compressed hydrogen dispensing systems and related components

    Energy Technology Data Exchange (ETDEWEB)

    Schefer, R.W.; Houf, W.G.; San Marchi, C. [Sandia National Laboratories, Livermore, CA 94551 (United States); Chernicoff, W.P.; Englom, L. [US DOT-RSPA, Research and Special Programs Administration, 400 7th St SW Washington, DC 20590 (United States)

    2006-08-15

    The equations are developed for the calculation of leak flow rates in various leak regimes. Leaks due to pressure-driven convection and due to permeation through metals are considered. For convective leaks, the conditions under which the flow transitions from laminar to turbulent and from subsonic to choked (sonic) flow are discussed. Equations are presented to calculate leak rates for subsonic laminar and turbulent flows, as well as choked (sonic) flow rates. Given the advantages of using noncombustible gases for leak testing and measurement, equations are also developed for calculating the equivalent leak rate of helium when it is used as a surrogate for the combustible gases hydrogen and methane in each of these flow regimes. Equations are derived for the permeation rate of hydrogen through several common metals. Tabulated data is presented for the permeation rates of hydrogen through pure iron and two types of stainless steel over a pressure range from 5000 to 15,000psi and a temperature range of -40-100{sup |}C. The results clearly show the sensitivity of flux to temperature, with over an order of magnitude increase in flux as the temperature is increased from ambient to 373K (100{sup |}C). Permeation rates are also found to vary significantly with material. For example, permeation rates for construction steel (as estimated from pure iron) are about three orders of magnitude higher than 403 stainless steel and nearly five orders of magnitude higher than type 316L stainless steel for a given temperature and pressure. Under many combinations of pressure and temperature, leak rates for Fe exceed the permissible gaseous hydrogen leak rates, while rates for 316L stainless steel are well below permissible permeation rates at all combinations of temperature and pressure considered. (author)

  9. Purge Procedures and Leak Testing for the Morgan Breathing System (MBS) 2000 Closed-Circuit Oxygen Rebreather

    National Research Council Canada - National Science Library

    Fothergill, David

    2005-01-01

    .... Since purging accounts for most of the O2 used when breathing on the MBS 2000, optimizing the purge procedure will maximize the duration of the O2 supply and minimize oxygen leaks into the chamber atmosphere...

  10. Containment integrity and leak testing. Procedures applied and experiences gained in European countries

    International Nuclear Information System (INIS)

    1987-01-01

    Containment systems are the ultimate safety barrier for preventing the escape of gaseous, liquid and solid radioactive materials produced in normal operation, not retained in process systems, and for keeping back radioactive materials released by system malfunction or equipment failure. A primary element of the containment shell is therefore its leak-tight design. The report describes the present containment concepts mostly used in European countries. The leak-testing procedures applied and the experiences gained in their application are also discussed. The report refers more particularly to pre-operational testing, periodic testing and extrapolation methods of leak rates measured at test conditions to expected leak rates at calculated accident conditions. The actual problems in periodic containment leak rate testing are critically reviewed. In the appendix to the report a summary is given of the regulations and specifications applied in different member countries

  11. Leak behaviors of steam generator tube-to-tubesheet joints from room temperature to 320 °C

    International Nuclear Information System (INIS)

    Bahn, Chi Bum; Majumdar, Saurin; Kasza, Ken E.; Shack, William J.

    2013-01-01

    To address concerns about excessive leakage from throughwall cracks in nuclear reactor tube-to-tubesheet joints under accident conditions, leak rates were measured experimentally by using tube-to-collar joint specimens and nitrogen gas. Rates were dependent on differential pressure between the tube internal surface and the crevice (i.e., the tube-to-collar interface region) and on temperature. As specimen temperature was raised to 320 °C, leak rates decreased gradually due to changes in gas properties and to differential thermal expansion between the Alloy 600 tubes and the SA508 collars. The leak rates did not change even after repeated temperature excursions to 320 °C, suggesting that thermally induced creep and subsequent contact pressure relaxation is negligible below that temperature. When considering factors that could increase flow resistance, such as oxidation, or debris on top of the tubesheet, the measured leak rates in this work are considered to be conservative. The test results were further used to validate the contact pressure calculation and a leak rate model. Highlights: ► Leak rates were measured by using tube-to-collar joint specimens. ► Leak rates were dependent on differential pressure between tube internal and joint interface. ► Leak rates decreased gradually as specimen temperature was raided to 320 °C. ► Differential thermal expansion between Alloy 600 tube and SA508 collar plays a major role on the leak behavior.

  12. Nuclear fuel element leak detection system

    International Nuclear Information System (INIS)

    John, C.D. Jr.

    1978-01-01

    Disclosed is a leak detection system integral with a wall of a building used to fabricate nuclear fuel elements for detecting radiation leakage from the nuclear fuel elements as the fuel elements exit the building. The leak detecting system comprises a shielded compartment constructed to withstand environmental hazards extending into a similarly constructed building and having sealed doors on both ends along with leak detecting apparatus connected to the compartment. The leak detecting system provides a system for removing a nuclear fuel element from its fabrication building while testing for radiation leaks in the fuel element

  13. Leak testing and repair of fusion devices

    International Nuclear Information System (INIS)

    Kozman, T.A.

    1983-01-01

    The leak testing, reporting and vacuum leak repair techniques of the MFTF yin-yang number one magnet system, the world's largest superconducting magnet system, are discussed. Based on this experience, techniques will be developed for testing and repairing leaks on the 42 MFTF-B magnets. The leak-hunting techniques for the yin-yang magnet systems were applied to two helium circuits (the coil bundle and guard vacuum; both require helium flow for magnet cooldown), their associated piping, liquid nitrogen radiation shields, and piping. Additionally, during MFTF-B operation there will be warm water plasma shields and piping that require leak checking

  14. Leak detection by vibrational diagnostic methods

    International Nuclear Information System (INIS)

    Siklossy, P.

    1983-01-01

    The possibilities and methods of leak detection due to mechanical failures in nuclear power plants are reviewed on the basis of the literature. Great importance is attributed to vibrational diagnostic methods for their adventageous characteristics which enable them to become final leak detecting methods. The problems of noise analysis, e.g. leak detection by impact sound measurements, probe characteristics, gain problems, probe selection, off-line analysis and correlation functions, types of leak noises etc. are summarized. Leak detection based on noise analysis can be installed additionally to power plants. Its maintenance and testing is simple. On the other hand, it requires special training and measuring methods. (Sz.J.)

  15. Using Decision Trees to Detect and Isolate Simulated Leaks in the J-2X Rocket Engine

    Science.gov (United States)

    Schwabacher, Mark A.; Aguilar, Robert; Figueroa, Fernando F.

    2009-01-01

    The goal of this work was to use data-driven methods to automatically detect and isolate faults in the J-2X rocket engine. It was decided to use decision trees, since they tend to be easier to interpret than other data-driven methods. The decision tree algorithm automatically "learns" a decision tree by performing a search through the space of possible decision trees to find one that fits the training data. The particular decision tree algorithm used is known as C4.5. Simulated J-2X data from a high-fidelity simulator developed at Pratt & Whitney Rocketdyne and known as the Detailed Real-Time Model (DRTM) was used to "train" and test the decision tree. Fifty-six DRTM simulations were performed for this purpose, with different leak sizes, different leak locations, and different times of leak onset. To make the simulations as realistic as possible, they included simulated sensor noise, and included a gradual degradation in both fuel and oxidizer turbine efficiency. A decision tree was trained using 11 of these simulations, and tested using the remaining 45 simulations. In the training phase, the C4.5 algorithm was provided with labeled examples of data from nominal operation and data including leaks in each leak location. From the data, it "learned" a decision tree that can classify unseen data as having no leak or having a leak in one of the five leak locations. In the test phase, the decision tree produced very low false alarm rates and low missed detection rates on the unseen data. It had very good fault isolation rates for three of the five simulated leak locations, but it tended to confuse the remaining two locations, perhaps because a large leak at one of these two locations can look very similar to a small leak at the other location.

  16. Correlates of minimal dating.

    Science.gov (United States)

    Leck, Kira

    2006-10-01

    Researchers have associated minimal dating with numerous factors. The present author tested shyness, introversion, physical attractiveness, performance evaluation, anxiety, social skill, social self-esteem, and loneliness to determine the nature of their relationships with 2 measures of self-reported minimal dating in a sample of 175 college students. For women, shyness, introversion, physical attractiveness, self-rated anxiety, social self-esteem, and loneliness correlated with 1 or both measures of minimal dating. For men, physical attractiveness, observer-rated social skill, social self-esteem, and loneliness correlated with 1 or both measures of minimal dating. The patterns of relationships were not identical for the 2 indicators of minimal dating, indicating the possibility that minimal dating is not a single construct as researchers previously believed. The present author discussed implications and suggestions for future researchers.

  17. Assessment of volume and leak measurements during CPAP using a neonatal lung model

    International Nuclear Information System (INIS)

    Fischer, H S; Roehr, C C; Proquitté, H; Wauer, R R; Schmalisch, G

    2008-01-01

    Although several commercial devices are available which allow tidal volume and air leak monitoring during continuous positive airway pressure (CPAP) in neonates, little is known about their measurement accuracy and about the influence of air leaks on volume measurement. The aim of this in vitro study was the validation of volume and leak measurement under CPAP using a commercial ventilatory device, taking into consideration the clinical conditions in neonatology. The measurement accuracy of the Leoni ventilator (Heinen and Löwenstein, Germany) was investigated both in a leak-free system and with leaks simulated using calibration syringes (2–10 ml, 20–100 ml) and a mechanical lung model. Open tubes of variable lengths were connected for leak simulation. Leak flow was measured with the flow-through technique. In a leak-free system the mean relative volume error ±SD was 3.5 ± 2.6% (2–10 ml) and 5.9 ± 0.7% (20–60 ml), respectively. The influence of CPAP level, driving flow, respiratory rate and humidification of the breathing gas on the volume error was negligible. However, an increasing F i O 2 caused the measured tidal volume to increase by up to 25% (F i O 2 = 1.0). The relative error ±SD of the leak measurements was −0.2 ± 11.9%. For leaks >19%, measured tidal volume was underestimated by more than 10%. In conclusion, the present in vitro study showed that the Leoni allowed accurate volume monitoring under CPAP conditions similar to neonates. Air leaks of up to 90% of patient flow were reliably detected. For an F i O 2 >0.4 and for leaks >19%, a numerical correction of the displayed volume should be performed

  18. Assessment of volume and leak measurements during CPAP using a neonatal lung model.

    Science.gov (United States)

    Fischer, H S; Roehr, C C; Proquitté, H; Wauer, R R; Schmalisch, G

    2008-01-01

    Although several commercial devices are available which allow tidal volume and air leak monitoring during continuous positive airway pressure (CPAP) in neonates, little is known about their measurement accuracy and about the influence of air leaks on volume measurement. The aim of this in vitro study was the validation of volume and leak measurement under CPAP using a commercial ventilatory device, taking into consideration the clinical conditions in neonatology. The measurement accuracy of the Leoni ventilator (Heinen & Löwenstein, Germany) was investigated both in a leak-free system and with leaks simulated using calibration syringes (2-10 ml, 20-100 ml) and a mechanical lung model. Open tubes of variable lengths were connected for leak simulation. Leak flow was measured with the flow-through technique. In a leak-free system the mean relative volume error +/-SD was 3.5 +/- 2.6% (2-10 ml) and 5.9 +/- 0.7% (20-60 ml), respectively. The influence of CPAP level, driving flow, respiratory rate and humidification of the breathing gas on the volume error was negligible. However, an increasing F(i)O(2) caused the measured tidal volume to increase by up to 25% (F(i)O(2) = 1.0). The relative error +/- SD of the leak measurements was -0.2 +/- 11.9%. For leaks > 19%, measured tidal volume was underestimated by more than 10%. In conclusion, the present in vitro study showed that the Leoni allowed accurate volume monitoring under CPAP conditions similar to neonates. Air leaks of up to 90% of patient flow were reliably detected. For an F(i)O(2) > 0.4 and for leaks > 19%, a numerical correction of the displayed volume should be performed.

  19. What is the optimal management of an intra-operative air leak in a colorectal anastomosis?

    Science.gov (United States)

    Mitchem, J B; Stafford, C; Francone, T D; Roberts, P L; Schoetz, D J; Marcello, P W; Ricciardi, R

    2018-02-01

    An airtight anastomosis on intra-operative leak testing has been previously demonstrated to be associated with a lower risk of clinically significant postoperative anastomotic leak following left-sided colorectal anastomosis. However, to date, there is no consistently agreed upon method for management of an intra-operative anastomotic leak. Therefore, we powered a noninferiority study to determine whether suture repair alone was an appropriate strategy for the management of an intra-operative air leak. This is a retrospective cohort analysis of prospectively collected data from a tertiary care referral centre. We included all consecutive patients with left-sided colorectal or ileorectal anastomoses and evidence of air leak during intra-operative leak testing. Patients were excluded if proximal diversion was planned preoperatively, a pre-existing proximal diversion was present at the time of surgery or an anastomosis was ultimately unable to be completed. The primary outcome measure was clinically significant anastomotic leak, as defined by the Surgical Infection Study Group at 30 days. From a sample of 2360 patients, 119 had an intra-operative air leak during leak testing. Sixty-eight patients underwent suture repair alone and 51 underwent proximal diversion or anastomotic reconstruction. The clinically significant leak rate was 9% (6/68; 95% CI: 2-15%) in the suture repair alone arm and 0% (0/51) in the diversion or reconstruction arm. Suture repair alone does not meet the criteria for noninferiority for the management of intra-operative air leak during left-sided colorectal anastomosis. Further repair of intra-operative air leak by suture repair alone should be reconsidered given these findings. Colorectal Disease © 2017 The Association of Coloproctology of Great Britain and Ireland.

  20. CT findings suggesting anastomotic leak and predicting the recovery period following gastric surgery

    Energy Technology Data Exchange (ETDEWEB)

    Kim, Tae Ho; Kim, Jung Hoon; Shin, Cheong-Il; Kim, Se Hyung; Han, Joon Koo; Choi, Byung Ihn [Seoul National University College of Medicine, Department of Radiology, Institute of Radiation Medicine, Jongno-gu, Seoul (Korea, Republic of)

    2015-07-15

    To assess diagnostic performance of routine CT for detecting anastomotic leak after gastric surgery, and analyse the relationship between recovery period and CT findings. We included 179 patients who underwent immediate CT and fluoroscopy after gastric surgery. Two reviewers retrospectively rated the possibility of leak on CT using a five-point scale focused on predefined CT findings. They also evaluated CT findings. Patients were categorised as: Group I, leak on fluoroscopy; Group II, possible leak on CT but negative on fluoroscopy; Group III, no leak. We analysed the relationship between recovery period and group. Area under the curve for detecting leak on CT was 0.886 in R1 and 0.668 in R2 with moderate agreement (k = 0.482). Statistically common CT findings for leak included discontinuity, large amount of air-fluid and wall thickening at anastomosis site (p < 0.05). Discontinuity at anastomosis site and a large air-fluid collection were independently associated with leak (p < 0.05). The recovery period including hospitalisation and postoperative fasting period was longer in Group I than Group II or III (p < 0.05). Group II showed a longer recovery period than Group III (p < 0.05). Postoperative routine CT was useful for predicting anastomotic leak using specific findings, and for predicting length of recovery period. (orig.)

  1. Sensitive helium leak detection in a deuterium atmosphere using a high-resolution quadrupole mass spectrometer

    International Nuclear Information System (INIS)

    Hiroki, S.; Abe, T.; Murakami, Y.

    1996-01-01

    In fusion machines, realizing a high-purity plasma is a key to improving the plasma parameters. Thus, leak detection is a necessary part of reducing the leak rate to a tolerable level. However, a conventional helium ( 4 He) leak detector is useless in fusion machines with a deuterium (D 2 ) plasma, because retained D particles on the first walls release D 2 for a long period and the released D 2 interferes with the signals from the leaked 4 He due to the near identical masses of 4.0026 u ( 4 He) and 4.0282 u (D 2 ). A high-resolution quadrupole mass spectrometer (HR-QMS) that we have recently developed, can detect a 4 He + population as small as 10 -4 peak in a D 2 atmosphere. Thus, the HR-QMS has been applied to detect 4 He leaks. To improve the minimum detectable limit of 4 He leak, a differentially pumped HR-QMS analyzer was attached to a chamber of the 4 He leak detector. In conclusion, the improved 4 He leak detector could detect 4 He leaks of the order of 10 -10 Pa · m 3 /s in a D 2 atmosphere. (Author)

  2. Development of acoustic leak detection and localization methods for inlet piping of fugen nuclear power plant

    International Nuclear Information System (INIS)

    Shimanskiy, Sergey; Iijima, Takashi; Naoi, Yosuke

    2004-01-01

    The development work carried out on Fugen NPP is focused on detection of a small leakage on the reactor's inlet feeder pipes at an early stage by an acoustic leak detection method with usage of high-temperature resistant microphones. Specifically, the leak rate of 0.046m 3 /h has been chosen as a target detection capability for this system. A cross-correlation technique has been studied for leak detection under low signal-noise ratios. The study shows that the sound diffusion on piping causes distortion of leak signals that results in their low correlation. A leak-location estimator and multi-channel correlation value, associated with estimated leak position, have been employed to detect such low-correlated leak signals. A method based on cross-correlation of signal spectral components has been proposed to deal with non-stationary leak signals. Joint-Time-Frequency-Analysis has been applied to analyze such signals, whilst a Wavelet decomposition technique has been used to extract their short-term spectral fluctuations. Since the spectral components are less affected by signal distortion, they provide higher correlation value and can be applied for leak detection under lower signal-noise ratios. The possibility of detecting and locating a small leakage by the methods proposed has been demonstrated by a number of simulation tests conducted on the Fugen NPP site. (author)

  3. Leaking electricity in domestic appliances

    International Nuclear Information System (INIS)

    Meier, Alan; Rosen, Karen

    1999-01-01

    Many types of home electronic equipment draw electric power when switched off or not performing their principal functions. Standby power use (or ''leaking electricity'') for most appliances ranges from 1 - 20 watts. Even though standby use of each device is small, the combined standby power use of all appliances in a home can easily exceed 50 watts. Leaking electricity is already responsible for 5 to 10 percent of residential electricity use in the United States and over 10 percent in Japan. An increasing number of white goods also have standby power requirements. There is a growing international effort to limit standby power to around one watt per device. New and existing technologies are available to meet this target at little or no extra cost

  4. Leak testing. Environment and workplaces

    International Nuclear Information System (INIS)

    1984-01-01

    Workplaces specified for leak testing are divided into clean workplaces of the 1st degree, clean workplaces of the second degree, clean workplaces of the third degree and semi-clean workplaces. Clean workplaces are further subdivided into permanent and temporary workplaces. For all said types of workplaces the standard sets the following provisions: basic equipment, machines and instrumentation, permitted and prohibited working activities and principles for maintenance and inspection. (E.S.)

  5. Hydrogen Leak Detection Sensor Database

    Science.gov (United States)

    Baker, Barton D.

    2010-01-01

    This slide presentation reviews the characteristics of the Hydrogen Sensor database. The database is the result of NASA's continuing interest in and improvement of its ability to detect and assess gas leaks in space applications. The database specifics and a snapshot of an entry in the database are reviewed. Attempts were made to determine the applicability of each of the 65 sensors for ground and/or vehicle use.

  6. Repair of EL4 leaks

    International Nuclear Information System (INIS)

    1985-03-01

    The reactor shutdown was decided on the 15th of November 1984, because the evolution of the carbon dioxide quantity in the helium blanket of the heavy water. Leaks have been localized on three different channels. Repairs have been made in hard conditions taking into account the reactor state (materials strongly irradiated). The restart has been authorized on the 24th of January 1985 [fr

  7. New age- and sex-specific criteria for QT prolongation based on rate correction formulas that minimize bias at the upper normal limits.

    Science.gov (United States)

    Rautaharju, Pentti M; Mason, Jay W; Akiyama, Toshio

    2014-07-01

    Existing formulas for rate-corrected QT (QTc) commonly fail to properly adjust the upper normal limits which are more critical than the mean QTc for evaluation of prolonged QT. Age- and sex-related differences in QTc are also often overlooked. Our goal was to establish criteria for prolonged QTc using formulas that minimize QTc bias at the upper normal limits. Strict criteria were used in selecting a study group of 57,595 persons aged 5 to 89 years (54% women) and to exclude electrocardiograms (ECG) with possible disease-associated changes. Two QT rate adjustment formulas were identified which both minimized rate-dependency in the 98 th percentile limits: QTcmod, based on an electrophysiological model (QTcMod = QTx(120 + HR)/180)), and QTcLogLin, a power function of the RR interval with exponents 0.37 for men and 0.38 for women. QTc shortened in men during adolescence and QTcMod became 13 ms shorter than in women at age 20-29 years. The sex difference was maintained through adulthood although decreasing with age. The criteria established for prolonged QTc were: Age < 40 years, men 430 ms, women 440 ms; Age 40 to 69, men 440 ms, women 450 ms; Age ≥ 70 years, men 455 ms, and women 460 ms. Sex difference in QTc originates from shortened QT in adolescent males. Upper normal limits for QTc vary substantially by age and sex, and it is essential to use age- and sex-specific criteria for evaluation of QT prolongation. Copyright © 2014 Elsevier Ireland Ltd. All rights reserved.

  8. Development of sodium leak detectors for PFBR

    International Nuclear Information System (INIS)

    Sylvia, J.I.; Rao, P. Vijayamohana; Babu, B.; Madhusoodanan, K.; Rajan, K.K.

    2012-01-01

    Highlights: ► Sodium leak detection system developed for PFBR using diverse principle. ► Miniature, remotely locatable diverse leak detector developed for Main Vessel. ► Mutual inductance type leak detectors designed and adapted for different locations. ► Sodium Ionisation detectors used for area monitoring. ► Crosswire type leak detector designed, developed and tested. - Abstract: The 500 MWe Prototype Fast Breeder Reactor (PFBR) is under advanced stage of construction at Kalpakkam near Chennai in India. The wide and high operating temperature, highly chemically active nature of sodium and its reaction with air make the sodium instrumentation complex over the conventional instrumentation. Over the years, traditional instruments such as wire type leak detectors, spark plug type leak detectors were developed and used in different sodium systems. The redundant and diverse leak detection method calls for development of special instrumentation for sodium systems which include sodium ionization (leak) detector for detecting minute sodium leak in addition to those systems based on mutual inductance principle. For detection of sodium leak from reactor Main Vessel (MV), diverse methods are used such as miniature, remotely locatable, Mutual Inductance type Leak Detector(MILD) and specially modified spark plug type leak detector. The design of MILD is suitably modified for detecting leak in double wall pipes and Diverse Safety Rod drive Mechanism (DSRDM). Steam/water leak in steam generator produces hydrogen and leads to high pressure and temperature in the system. Rupture disc is used as a safety device which punctures itself due to sudden pressure rise. To detect the discharge of sodium and its reaction products at the downstream of the rupture disc due to bursting of the rupture disc, cross wire type leak detector has been designed, developed and tested. The selection of the leak detection system depends on the location where leak has to be detected. This paper

  9. Return-to-Duty Rates Following Minimally Invasive Spine Surgery Performed on Active Duty Military Patients in an Ambulatory Surgery Center.

    Science.gov (United States)

    Granger, Elder; Prada, Stefan; Bereczki, Zoltan; Weiss, Michael; Wade, Chip; Davis, Reginald

    2018-05-21

    Low back pain is a primary health care utilization driver in the US population. Health care evaluation visits for low back pain are as common as medical evaluation for the common cold. Low back pain is the most common reason for reductions in activities of daily living and work activity in the general population. Although these statistics are compelling, in the military population, there is arguably a significantly greater economic impact on the military population, as the cost to train, retain, and deploy a service member is a tremendous cost. The current study retrospectively examines surgical outcomes, return to duty, and patient-centric outcomes among 82 active duty or reserve military patients who underwent an outpatient minimally invasive spine surgery Laminotomy Foraminotomy Decompression for the treatment of lumbar spinal stenosis in an ambulatory surgery center. Overall, our results indicate that within the 82 active duty military service members, 100% of the service members return to duty within 3 mo. Additionally, there was a significant reduction in self-reported pain and disability 12 mo postoperative, whereas the average length of surgery was 62 min with an average estimated blood loss of 30.64 mL. The current study indicates that minimally invasive procedures for the treatment of lumbar spinal stenosis in an ambulatory surgery center setting are an effective option for active duty servicemen to reduce return-to-duty rates and symptomatic back-related pain and disability.

  10. Diagnostic instrumentation for detection of the onset of steam tube leaks in PWRs

    International Nuclear Information System (INIS)

    Roach, W.H.

    1984-01-01

    Four tasks are addressed in this study of the detection of steam tube leaks: determination of which physical parameters indicate the onset of steam generator tube leaks; establishing performance goals for diagnostic instruments which could be used for early detection of steam generator tube leaks; defining the diagnostic instrumentation and their location which satisfy Items 1 and 2; and assessing the need for diagnostic data processing and display. Parameters are identified, performance goals established and sensor types and locations are specified in the report, with emphasis on the use of existing instrumentation with a minimum of retrofitting. A simple algorithm is developed which yields the leak rate as a function of known or measurable quantities. The conclusion is that leak rates of less than one-tenth gram per second should be detectable with existing instrumentation

  11. What Is the Risk of Anastomotic Leak After Repeat Intestinal Resection in Patients With Crohn's Disease?

    Science.gov (United States)

    Johnston, W Forrest; Stafford, Caitlin; Francone, Todd D; Read, Thomas E; Marcello, Peter W; Roberts, Patricia L; Ricciardi, Rocco

    2017-12-01

    Approximately half of Crohn's patients require intestinal resection, and many need repeat resections. The purpose of this study was to evaluate the increased risk of clinical anastomotic leak in patients with a history of previous intestinal resection undergoing repeat resection with anastomosis for Crohn's disease. This was a retrospective analysis of prospectively collected departmental data with 100% capture. The study was conducted at the department of colorectal surgery in a tertiary care teaching hospital between July 2007 and March 2016. A cohort of consecutive patients with Crohn's disease who were treated with intestinal resection and anastomosis, excluding patients with proximal fecal diversion, were included. The cohort was divided into 2 groups, those with no previous resection compared with those with previous resection. Clinical anastomotic leak within 30 days of surgery was measured. Of the 206 patients who met criteria, 83 patients had previous intestinal resection (40%). The 2 groups were similar in terms of patient factors, immune-suppressing medication use, and procedural factors. Overall, 20 clinical anastomotic leaks were identified (10% leak rate). There were 6 leaks (5%) detected in patients with no previous intestinal resection and 14 leaks (17%) detected in patients with a history of previous intestinal resection (p leak in patients with Crohn's disease with previous resection compared with no previous resection was 3.5 (95% CI, 1.3-9.4). Patients with 1 previous resection (n = 53) had a leak rate of 13%, whereas patients with ≥2 previous resections (n = 30) had a leak rate of 23%. The number of previous resections correlated with increasing risk for clinical anastomotic leak (correlation coefficient = 0.998). This was a retrospective study with limited data to perform a multivariate analysis. Repeat intestinal resection in patients with Crohn's disease is associated with an increased rate of anastomotic leakage when compared with initial

  12. Effect of heat transfer tube leak on dynamic characteristic of steam generator

    International Nuclear Information System (INIS)

    Sun Baozhi; Shi Jianxin; Li Na; Zheng Lusong; Liu Shanghua; Lei Yu

    2015-01-01

    Taking the steam generator of Daya Bay Nuclear Power Station as the research object, one-dimensional dynamic model of the steam generator based on drift flux theory and leak model of heat transfer tube were established. Steady simulation of steam generator under different conditions was carried out. Based on verifying the drift flux model and leak model of heat transfer tube, the effect of leak location and flow rate under different conditions on steam generator's key parameters was studied. The results show that the drift flux model and leak model can reflect the law of key parameter change accurately such as vapor mass fraction and steam pressure under different leak cases. The variation of the parameters is most apparent when the leak is at the entrance of boiling section and vapor mass fraction varies from 0.261 to 0.163 when leakage accounts for 5% of coolant flow rate. The successful prediction of the effect of heat transfer tube leak on dynamic characteristics of the steam generator based on drift flux theory supplies some references for monitoring and taking precautionary measures to prevent heat transfer tube leak accident. (authors)

  13. Leak detection device for control rod drive and detection method therefor

    International Nuclear Information System (INIS)

    Imasaki, Yoshio.

    1997-01-01

    The present invention provides a detection device for leak of cooling water from a sealed axial portion of control rod drives (CRD) disposed in a BWR type reactor and a monitoring method therefor. Namely, the CRD transfers rotation at the sealed axial portion and elevates/lowers a piston to insert/withdraw control rod into/from the reactor core. High pressure water is injected upon occurrence of scram to urge the piston upwardly thereby rapidly inserting the control rods. Leak detection pipelines are laid from the sealed axial portion. A flow glass is connected to the leak detection pipelines. Then, cooling water leaked from the sealed axial portion flows in the leak detection pipelines and flows into the flow glass. The flow rate of cooling water leaked from the sealed axial portion of the CRD can thus be detected by monitoring the flow glass. In addition, a flowmeter is connected to the leak detection pipelines, or the flowmeter and the flow glass are connected, and a flowmeter is connected downstream. Then, the flow rate of the leaked cooling water can be detected automatically. (I.S.)

  14. Water leak localization and recovery in Tore Supra

    International Nuclear Information System (INIS)

    Martinez, A.; Samaille, F.; Chantant, M.; Hatchressian, J.C.

    2007-01-01

    For almost 20 years at Tore Supra, plasma facing components (PFCs) are actively cooled by a pressurized water primary loop. Tore Supra can be considered as ITER relevant on this particular aspect. During plasma operation, it happened, that unexpected localized power deposits damaged a PFC leading to more or less large water leaks in the vacuum vessel. The improvement of the procedure to localize the leaky circuits, the investigation of technical solutions for minimizing the amount of water from steam condensation in the vacuum vessel and the optimisation of the quality of the draining and the drying of Tore Supra cooling loop circuits are the result of the experience gained during several years by the analysis of the water leak from plasma facing components (PFCs) and their consequences. Different new specific systems designed and installed during this year to fulfil these objectives are described in this paper

  15. Minimally invasive orthognathic surgery.

    Science.gov (United States)

    Resnick, Cory M; Kaban, Leonard B; Troulis, Maria J

    2009-02-01

    Minimally invasive surgery is defined as the discipline in which operative procedures are performed in novel ways to diminish the sequelae of standard surgical dissections. The goals of minimally invasive surgery are to reduce tissue trauma and to minimize bleeding, edema, and injury, thereby improving the rate and quality of healing. In orthognathic surgery, there are two minimally invasive techniques that can be used separately or in combination: (1) endoscopic exposure and (2) distraction osteogenesis. This article describes the historical developments of the fields of orthognathic surgery and minimally invasive surgery, as well as the integration of the two disciplines. Indications, techniques, and the most current outcome data for specific minimally invasive orthognathic surgical procedures are presented.

  16. Minimally invasive approach of panfacial fractures

    Directory of Open Access Journals (Sweden)

    Yudi Wijaya

    2017-08-01

    Full Text Available Background. Panfacial fractures involves fractures of several bones of face. They are associated with malocclusion, dish face deformity, enopthalmos, diplopia, cerebrospinal fluid leak and soft tissue injuries. Purpose. The purpose of this paper is to present a case of minimizing surgical wound and morbidity. Case. A 40 year old female presented with severe maxillofacial injuries caused by motor vehicle collisions about 5 days prior to admission. The assessment of the patient is mild head injury, panfacial fractures, lacerated wound at face,  rupture of globe of occular sinistra. An open reduction and internal fixation  (ORIF and enucleation of globe occular sinistra was performed.  Intraoral vestibular incision is made in the upper and lower vestibular region. Mucoperiosteal flap elevation of vestibular will exposure of the anterior maxilla and mandibular fractures. Intermaksilary fixation within 3 week and restore aesthetic with prosthesis fitting eyeball and denture. Discusion. The goal of  treatment of  panfacial fracture is to restore both the functions and pre-injury 3-dimensional facial contours. To achieve this goal two common  sequences of management of Panfacial fractures are proposed, “Bottom up and inside out” or “Top down and outside in”. Other sequences exist but there are variations of these two major approaches. Conclusion. A minimally invasive approach to  the fracture site is an alternative method  to manage panfacial fracture with a simple, effective and lower complication rate.

  17. Application of leak-before-break criteria to pressurized water reactors

    International Nuclear Information System (INIS)

    Roege, P.; Day, B.; Beckjord, E.; Golay, M.

    1986-01-01

    The possibility of consequential damage to safety-related systems or components after postulated pipe breaks in Light Water Reactors has led to the installation of pipe restraints capable of withstanding the loads in such an accident. These restraints are a significant part of initial capital cost, and because of their size and location, impede plant maintenance. The Piping Review Committee of the U.S. Nuclear Regulatory Commission has concluded that, subject to fulfillment of certain criteria, the pipe restraints for pressurized water reactor main coolant piping are not necessary, because the failure mode of this piping is such that it will leak before it will break, and the leakage of reactor coolant is large enough to detect. In this study, we examine the piping systems of a 4-loop 1,150 MWe pressurized water reactor, determining the crack size that would be stable from a fracture mechanics point of view, and the range of leak rates that would ensue. We then consider the sensitivity of conventional leak detection systems, and find that pipe sizes down to 45 cm in diameter would meet the leak-before-break criteria. Improvements in the sensitivity of conventional leak detectors would extend this range down to pipe sizes down to the range of 20 - 45 cm in diameter. The development of local leak detection systems which would respond to leaks in compartments or confined areas would make it possible to apply the criteria to sizes as low as 10 - 20 cm in diameter, which appear to be the limit of the net cost savings of eliminating pipe restraints and adding additional leak detection instrumentation. Extending the leak-before-break concept into this smallest pipe range may require improved precision in crack definition, flow modeling, and leak detection. Better detection of leaks may also require use of new detection methods coupled to novel approaches to piping system design. (J.P.N.)

  18. Acoustic leak detection of LMFBR steam generator

    International Nuclear Information System (INIS)

    Kumagai, Hiromichi; Yoshida, Kazuo

    1993-01-01

    The development of a water leak detector with short response time for LMFBR steam generators is required to prevent the failure propagation caused by the sodium-water reaction and to maintain structural safety in steam generators. The development of an acoustic leak detector assuring short response time has attracted. The purpose of this paper is to confirm the basic detection feasibility of the active acoustic leak detector, and to investigate the leak detection method by erasing the background noise by spectrum analysis of the passive acoustic leak detector. From a comparison of the leak detection sensitivity of the active and the passive method, the active method is not influenced remarkably by the background noise, and it has possibility to detect microleakage with short response time. We anticipate a practical application of the active method in the future. (author)

  19. Water leak detection in steam generator of Super Phenix

    International Nuclear Information System (INIS)

    Kong, N.; Brunet, M.; Garnaud, P.; Ghaleb, D.

    1990-01-01

    With the intent of detecting water leaks inside steam generators, we developed a third system, called acoustic detector, to complement hydrogen detectors and rupture disks (burst disks). The role of the acoustic system is to enable rapid intervention in the event of a leak growing rapidly which could rupture neighbouring tubes. In such a case, the detectable flow rate of the leak varies from a few tens of g/s to a few hundred g/s. At the Super Phenix, three teams work in parallel in complementary frequency bands: EDF (0-20 kHz), CEA/SPCI (20-100 kHz) and CEA/STA (50-300 kHz). The simulation of water leaks in the steam generator by the argon injections performed to date at 50% of the rated power has shown promising results. An anomaly in the evolution of the background noise at more than 50% loading of one of the two instrumented steam generators would make difficult any extrapolation to full power behaviour. 5 refs, 6 figs, 1 tab

  20. Leak detection of KNI seals

    International Nuclear Information System (INIS)

    Baranyai, G.; Peter, A.; Windberg, P.

    1990-03-01

    In Unit 3 and 4 of the Paks Nuclear Power Plant, Hungary, KNI type seals are used as lead-throughs with conical nickel sealing rings. Their failure can be critical for the operation of the reactor. An Acoustical Leak Detection System (ALDS) was constructed and tested for the operational testing of the seals. Some individual papers are presented in this collection on the calibration and testing of the ALDS intended to be placed on the top of the reactor vessels. The papers include simulation measurements of Unit 3 of NPP, laboratory experiments, evaluation of measurements, and further development needs with the ALDS. (R.P.) 50 figs.; 19 tabs

  1. Vacuum leak detector and method

    Science.gov (United States)

    Edwards, Jr., David

    1983-01-01

    Apparatus and method for detecting leakage in a vacuum system involves a moisture trap chamber connected to the vacuum system and to a pressure gauge. Moisture in the trap chamber is captured by freezing or by a moisture adsorbent to reduce the residual water vapor pressure therein to a negligible amount. The pressure gauge is then read to determine whether the vacuum system is leaky. By directing a stream of carbon dioxide or helium at potentially leaky parts of the vacuum system, the apparatus can be used with supplemental means to locate leaks.

  2. Small leak detection by measuring surface oscillation during sodium-water reaction in steam generator

    International Nuclear Information System (INIS)

    Nei, Hiromichi; Hori, Masao

    1977-01-01

    Small leak sodium-water reaction tests were conducted to develop various kinds of leak detectors for the sodium-heated steam generator in FBR. The super-heated steam was injected into sodium in a reaction vessel having a sodium free surface, simulating the steam generator. The level gauge in the reaction vessel generated the most reliable signal among detectors, as long as the leak rates were relatively high. The level gauge signal was estimated to be the sodium surface oscillation caused by hydrogen bubbles produced in sodium-water reaction. Experimental correlation was derived, predicting the amplitude as a function of leak rate, hydrogen dissolution ratio, bubble rise velocity and other parameters concerned, assuming that the surface oscillation is in proportion to the gas hold-up. The noise amplitude under normal operation without water leak was increased with sodium flow rate and found to be well correlated with Froud number. These two correlations predict that a water leak in a ''MONJU'' class (300 MWe) steam generator could possibly be detected by level gauges at a leak rate above 2 g/sec. (auth.)

  3. Leaking tankers: how much oil was spilled?

    International Nuclear Information System (INIS)

    Simecek-Beatty, D. A.; Lehr, W. J.; Lankford, J. F.

    1997-01-01

    A model to estimate leak rates from tankers has been developed for use in emergency situations when more direct oil-loss estimation methods are not available. The model includes algorithms for gravity outflow and air and water ingestion. Three laboratory tests were conducted using fresh water and canola oil to evaluate the model output. Comparison with results from the laboratory experiments indicate good correlation of model results with measured data. However, it is not yet possible in the case of very large crude carriers to answer the question 'how much oil was spilled?' Sensitivity analysis and further laboratory testing were suggested to determine the effect of factors such as: pressure vacuum relief valves that prevent cavitation in the event of tank puncture; changing outside water levels due to wave and tidal action; tank and hole dimensions; and the amount and density of the product.10 refs., 4 figs

  4. Acoustic emission leak monitoring system LMS-96

    International Nuclear Information System (INIS)

    Liska, J.; Cvrcek, M.; Mueller, L.

    1997-01-01

    On-line acoustic emission leak monitoring under industrial conditions of nuclear power plants is a problem with specific features setting specific demands on the leak monitoring system. The paper briefly reviews those problems (attenuation pattern of a real structure, acoustic background, alarm system, etc.) and the solution of some of them is discussed. Information is presented on the Acoustic Emission Leak Monitoring System LMS-96 by SKODA NUCLEAR MACHINERY and the system's function is briefly described. (author)

  5. Leak detection using structure-borne noise

    Science.gov (United States)

    Holland, Stephen D. (Inventor); Chimenti, Dale E. (Inventor); Roberts, Ronald A. (Inventor)

    2010-01-01

    A method for detection and location of air leaks in a pressure vessel, such as a spacecraft, includes sensing structure-borne ultrasound waveforms associated with turbulence caused by a leak from a plurality of sensors and cross correlating the waveforms to determine existence and location of the leak. Different configurations of sensors and corresponding methods can be used. An apparatus for performing the methods is also provided.

  6. Hepatobiliary scintigraphy in patients with bile leaks

    International Nuclear Information System (INIS)

    Carichner, S.L.; Nagle, C.E.

    1987-01-01

    Hepatobiliary scintigraphy has been recognized as a useful tool in detecting the presence and sites of bile leaks. The clinical settings in which bile leaks are likely to occur, as well as some of the scintigraphic patterns seen in patients with bile leaks, are reviewed here. Tips for technologists are offered on interventions that might enhanced the quality of information available to the nuclear physician

  7. Young Mania Rating Scale: how to interpret the numbers? Determination of a severity threshold and of the minimal clinically significant difference in the EMBLEM cohort.

    Science.gov (United States)

    Lukasiewicz, Michael; Gerard, Stephanie; Besnard, Adeline; Falissard, Bruno; Perrin, Elena; Sapin, Helene; Tohen, Mauricio; Reed, Catherine; Azorin, Jean-Michel

    2013-03-01

    The aim of this analysis was to identify Young Mania Rating Scale (YMRS) meaningful benchmarks for clinicians (severity threshold, minimal clinically significant difference [MCSD]) using the Clinical Global Impressions Bipolar (CGI-BP) mania scale, to provide a clinical perspective to randomized clinical trials (RCTs) results. We used the cohort of patients with acute manic/mixed state of bipolar disorders (N = 3459) included in the European Mania in Bipolar Longitudinal Evaluation of Medication (EMBLEM) study. A receiver-operating characteristic analysis was performed on randomly selected patients to determine the YMRS optimal severity threshold with CGI-BP mania score ≥ "Markedly ill" defining severity. The MCSD (clinically meaningful change in score relative to one point difference in CGI-BP mania for outcome measures) of YMRS, was assessed with a linear regression on baseline data. At baseline, YMRS mean score was 26.4 (±9.9), CGI-BP mania mean score was 4.8 (±1.0) and 61.7% of patients had a score ≥ 5. The optimal YMRS severity threshold of 25 (positive predictive value [PPV] = 83.0%; negative predictive value [NPV] = 66.0%) was determined. In this cohort, a YMRS score of 20 (typical cutoff for RCTs inclusion criteria) corresponds to a PPV of 74.6% and to a NPV of 77.6%, meaning that the majority of patients included would be classified as severely ill. The YMRS minimal clinically significant difference was 6.6 points. Copyright © 2013 John Wiley & Sons, Ltd.

  8. Biphasic decay of the Ca transient results from increased sarcoplasmic reticulum Ca leak

    Science.gov (United States)

    Sankaranarayanan, Rajiv; Li, Yatong; Greensmith, David J.; Eisner, David A.

    2016-01-01

    Key points Ca leak from the sarcoplasmic reticulum through the ryanodine receptor (RyR) reduces the amplitude of the Ca transient and slows its rate of decay.In the presence of β‐adrenergic stimulation, RyR‐mediated Ca leak produces a biphasic decay of the Ca transient with a fast early phase and a slow late phase.Two forms of Ca leak have been studied, Ca‐sensitising (induced by caffeine) and non‐sensitising (induced by ryanodine) and both induce biphasic decay of the Ca transient.Only Ca‐sensitising leak can be reversed by traditional RyR inhibitors such as tetracaine.Ca leak can also induce Ca waves. At low levels of leak, waves occur. As leak is increased, first biphasic decay and then slowed monophasic decay is seen. The level of leak has major effects on the shape of the Ca transient. Abstract In heart failure, a reduction in Ca transient amplitude and contractile dysfunction can by caused by Ca leak through the sarcoplasmic reticulum (SR) Ca channel (ryanodine receptor, RyR) and/or decreased activity of the SR Ca ATPase (SERCA). We have characterised the effects of two forms of Ca leak (Ca‐sensitising and non‐sensitising) on calcium cycling and compared with those of SERCA inhibition. We measured [Ca2+]i with fluo‐3 in voltage‐clamped rat ventricular myocytes. Increasing SR leak with either caffeine (to sensitise the RyR to Ca activation) or ryanodine (non‐sensitising) had similar effects to SERCA inhibition: decreased systolic [Ca2+]i, increased diastolic [Ca2+]i and slowed decay. However, in the presence of isoproterenol, leak produced a biphasic decay of the Ca transient in the majority of cells while SERCA inhibition produced monophasic decay. Tetracaine reversed the effects of caffeine but not of ryanodine. When caffeine (1 mmol l−1) was added to a cell which displayed Ca waves, the wave frequency initially increased before waves disappeared and biphasic decay developed. Eventually (at higher caffeine concentrations), the

  9. Pressure transients resulting from sodium-water reaction following a large leak in LMFBR steam generator

    International Nuclear Information System (INIS)

    Rajput, A.K.

    1984-01-01

    The study of sodium water reaction, following a large leak, concerns primarily with the estimation of pressure/flow transients that are developed in the steam generator and the associated secondary circuit. This paper describes the mathematical formulations used in SWRT (Sodium Water Reaction Transients) code developed to estimate such pressure transients for FBTR plant. The results, obtained using SWRT have been presented for a leak in economiser (20m from bottom water header) and for a leak in super heater portions. A time lag of 50 m sec was considered for rupture disc takes to burst once the pressure experienced by it exceeds the set value. Also described in annexure to this paper is the mathematical formulation for two phase transient flow for the better estimation of leak rate from the ruptured end of the damaged heat transfer tube. This leak model considers slip but assumes thermal equilibrium between the liquid and vapour phases

  10. NDE of stainless steel and on-line leak monitoring of LWRs

    International Nuclear Information System (INIS)

    Kupperman, D.S.; Claytor, T.N.; Mathieson, T.; Prine, D.W.

    1985-10-01

    The GARD/ANL acoustic leak detection system is under evaluation in the laboratory. Results of laboratory tests with simulated acoustic leak signals and acoustic signals from field-induced intergranular stress corrosion cracks (IGSCCs) indicate that cross-correlation techniques can be used to locate the position of a leak. Leaks from a 2-in. ball valve and a flange were studied and compared with leaks from IGSCCs and fatigue cracks. The dependence of acoustic signal on flow rate and frequency for the valve and the flange was comparable to that of fatigue cracks (thermal and mechanical) and different from that of IGSCCs. Two pipe-to-endcap weldments with overlays were examined. Because the amount of cracking in the specimens was limited, the emphasis was on trying understand the nature of crack overcalling. Four 60-mm-thick cast stainless steel plates with microstructures ranging from equiaxed to primarily columnar grains have been examined with ultrasonic waves. 13 refs., 23 figs

  11. Theoretical and experimental investigation of magnetic field related helium leak in helium vessel of a large superconducting magnet

    Science.gov (United States)

    Bhattachryya, Pranab; Gupta, Anjan Dutta; Dhar, S.; Sarma, P. R.; Mukherjee, Paramita

    2017-06-01

    The helium vessel of the superconducting cyclotron (SCC) at the Variable Energy Cyclotron centre (VECC), Kolkata shows a gradual loss of insulation vacuum from 10-7 mbar to 10-4 mbar with increasing coil current in the magnet. The insulation vacuum restores back to its initial value with the withdrawal of current. The origin of such behavior has been thought to be related to the electromagnetic stress in the magnet. The electromagnetic stress distribution in the median plane of the helium vessel was studied to figure out the possible location of the helium leak. The stress field from the possible location was transferred to a simplified 2D model with different leak geometries to study the changes in conductance with coil current. The leak rate calculated from the changes in the leak geometry was compared with the leak rate calculated from the experimental insulation vacuum degradation behavior to estimate the initial leak shape and size.

  12. Assessment of Field Experience Related to Pressurized Water Reactor Primary System Leaks

    International Nuclear Information System (INIS)

    Ware, A.G.; Hsu, C.; Atwood, C.L.; Sattison, M.B.; Hartley, R.S.; Shah, V.N.

    1999-01-01

    This paper presents our assessment of field experience related to pressurized water reactor (PWR) primary system leaks in terms of their number and rates, how aging affects frequency of leak events, the safety significance of such leaks, industry efforts to reduce leaks, and effectiveness of current leak detection systems. We have reviewed the licensee event reports to identify the events that took place during 1985 to the third quarter of 1996, and reviewed related technical literature and visited PWR plants to analyze these events. Our assessment shows that USNRC licensees have taken effective actions to reduce the number of leak events. One main reason for this decreasing trend was the elimination or reportable leakages from valve stem packing after 1991. Our review of leak events related to vibratory fatigue reveals a statistically significant decreasing trend with age (years of operation), but not in calendar time. Our assessment of worldwide data on leakage caused by thermal fatigue cracking is that the fatigue of aging piping is a safety significant issue. Our review of leak events has identified several susceptible sites in piping having high safety significance; but the inspection of some of these sites is not required by the ASME Code. These sites may be included in the risk-informed inspection programs

  13. Assessment of Field Experience Related to Pressurized Water Reactor Primary System Leaks

    International Nuclear Information System (INIS)

    Shah, Vikram Naginbhai; Ware, Arthur Gates; Atwood, Corwin Lee; Sattison, Martin Blaine; Hartley, Robert Scott; Hsu, C.

    1999-01-01

    This paper presents our assessment of field experience related to pressurized water reactor (PWR) primary system leaks in terms of their number of rates, how aging affects frequency of leak events, the safety significance of such leaks, industry efforts to reduce leaks, and effectiveness of current leak detection systems. We have reviewed the licensee event reports to identify the events that took place during 1985 to the third quarter of 1996, and reviewed related technical literature and visited PWR plants to analyze these events. Our assessment shows that USNRC licensees have taken effective actions to reduce the number of leak events. One main reason for this decreasing trend was the elimination or reportable leakages from valve stem packing after 1991. Our review of leak events related to vibratory fatigue reveals a statistically significant decreasing trend with age (years of operation), but not in calendar time. Our assessment of worldwide data on leakage caused by thermal fatigue cracking is that the fatigue of aging piping is a safety significant issue. Our review of leak events has identified several susceptible sites in piping having high safety significance; but the inspection of some of these sites is not required by the ASME Code. These sites may be included in the risk-informed inspection programs

  14. Active acoustic leak detection for LMFBR steam generators. Pt. 7. Potential for small leak detection

    International Nuclear Information System (INIS)

    Kumagai, Hiromichi; Yoshida, Kazuo

    1998-01-01

    In order to prevent the expansion of tube damage and to maintain structural integrity in the steam generators (SGs) of fast breeder reactors (FBR), it is necessary to detect precisely and immediately the leakage of water from heat transfer tubes. Therefore, an active acoustic method, which detects the sound attenuation due to bubbles generated in the sodium-water reactions, is being developed. Previous studies have revealed that the active acoustic method can detect bubbles of 10 l/s (equivalence water leak rate about 10 g/s) within 10 seconds in practical steam generators. In order to prevent the expansion of damage to neighboring tubes, however, it is necessary to detect smaller leakage of water from heat transfer tubes. In this study, in order to evaluate the detection sensitivity of the active method, the signal processing methods for emitter and receiver sound and the detection method for leakage within 1 g/s are investigated experimentally, using an SG full-sector model that simulates the actual SGs. A typical result shows that detection of 0.4 l/s air bubbles (equivalent water leak rate about 0.4 g/s) takes about 80 seconds, which is shorter than the propagation time of damage to neighboring tubes. (author)

  15. Use of duraseal in repair of cerebrospinal fluid leaks.

    Science.gov (United States)

    Chin, Christopher J; Kus, Lukas; Rotenberg, Brian W

    2010-10-01

    The purpose of our article is to review the use of the DuraSeal Sealant System (Confluent Surgical Inc., Waltham, MA) in the repair of complex cerebrospinal fluid (CSF) leaks in endoscopic skull-base surgery. Retrospective chart review. London Health Sciences Centre. A database of endoscopic skull-base cases between 2007 and 2009 that involved CSF leakage repaired with DuraSeal was created. Demographic data and operative reports were collected and analyzed qualitatively. Recurrence of CSF leak after repair. Five cases were identified that met study criteria. In four of the five cases, the repair was successful. There were no complications related to DuraSeal use. Comparison to a subset of patients using Tisseel Fibrin Sealant (Baxter, Toronto, ON) for repair did not show a significant difference in failure rate (χ2 = 0.029, p = .858). There are a variety of techniques described to repair CSF rhinorrhea, with various studies demonstrating the advantages of using tissue glues in CSF leak repairs. We used DuraSeal in five patients to enhance graft strength and form a watertight seal. The system was effective in the majority of patients. Our study is the first to report on endoscopic endonasal repair of CSF leaks using DuraSeal.

  16. Analyzing User Awareness of Privacy Data Leak in Mobile Applications

    Directory of Open Access Journals (Sweden)

    Youngho Kim

    2015-01-01

    Full Text Available To overcome the resource and computing power limitation of mobile devices in Internet of Things (IoT era, a cloud computing provides an effective platform without human intervention to build a resource-oriented security solution. However, existing malware detection methods are constrained by a vague situation of information leaks. The main goal of this paper is to measure a degree of hiding intention for the mobile application (app to keep its leaking activity invisible to the user. For real-world application test, we target Android applications, which unleash user privacy data. With the TaintDroid-ported emulator, we make experiments about the timing distance between user events and privacy leaks. Our experiments with Android apps downloaded from the Google Play show that most of leak cases are driven by user explicit events or implicit user involvement which make the user aware of the leakage. Those findings can assist a malware detection system in reducing the rate of false positive by considering malicious intentions. From the experiment, we understand better about app’s internal operations as well. As a case study, we also presents a cloud-based dynamic analysis framework to perform a traffic monitor.

  17. Development of acoustic leak detection system in PNC

    International Nuclear Information System (INIS)

    Tanabe, H.; Kuroha, M.

    1990-01-01

    The development of an acoustic leak detector is under way at PNC as a detection system that has potential of quick response and high reliability for larger steam generators of future LMFBR plants. The studies have two aspects, i.e., an acoustic wave analysis in various sodium-water reactions and a background noise (BGN) analysis in a sodium-heated 50MWt steam generator (50MWGS). In the former analysis, wave profiles of the sodium-water reaction sound were analyzed and compared with those of inert gas injection sound. The comparison revealed that there were no wave profiles specific to a sodium-water reaction sound. The latter clarified that major acoustic sources in the steam generator were sodium flow and steam generation/flow and that the water leak rate at which a noise level was comparable with that of the background noise was about 0.5 g/sec. in the evaporator of 50MWSG. The estimation of acceleration levels of BGN and leak sounds in other plants reveals that an intermediate leak is detectable in the Monju evaporator with a present acoustic detection system. (author). 2 refs, 9 figs

  18. Electrical detection of liquid lithium leaks from pipe joints

    Energy Technology Data Exchange (ETDEWEB)

    Schwartz, J. A., E-mail: jschwart@pppl.gov; Jaworski, M. A.; Mehl, J.; Kaita, R.; Mozulay, R. [Princeton Plasma Physics Laboratory, Princeton, New Jersey 08543-0451 (United States)

    2014-11-15

    A test stand for flowing liquid lithium is under construction at Princeton Plasma Physics Laboratory. As liquid lithium reacts with atmospheric gases and water, an electrical interlock system for detecting leaks and safely shutting down the apparatus has been constructed. A defense in depth strategy is taken to minimize the risk and impact of potential leaks. Each demountable joint is diagnosed with a cylindrical copper shell electrically isolated from the loop. By monitoring the electrical resistance between the pipe and the copper shell, a leak of (conductive) liquid lithium can be detected. Any resistance of less than 2 kΩ trips a relay, shutting off power to the heaters and pump. The system has been successfully tested with liquid gallium as a surrogate liquid metal. The circuit features an extensible number of channels to allow for future expansion of the loop. To ease diagnosis of faults, the status of each channel is shown with an analog front panel LED, and monitored and logged digitally by LabVIEW.

  19. Taxonomic minimalism.

    Science.gov (United States)

    Beattle, A J; Oliver, I

    1994-12-01

    Biological surveys are in increasing demand while taxonomic resources continue to decline. How much formal taxonomy is required to get the job done? The answer depends on the kind of job but it is possible that taxonomic minimalism, especially (1) the use of higher taxonomic ranks, (2) the use of morphospecies rather than species (as identified by Latin binomials), and (3) the involvement of taxonomic specialists only for training and verification, may offer advantages for biodiversity assessment, environmental monitoring and ecological research. As such, formal taxonomy remains central to the process of biological inventory and survey but resources may be allocated more efficiently. For example, if formal Identification is not required, resources may be concentrated on replication and increasing sample sizes. Taxonomic minimalism may also facilitate the inclusion in these activities of important but neglected groups, especially among the invertebrates, and perhaps even microorganisms. Copyright © 1994. Published by Elsevier Ltd.

  20. Experiments on graphite block gaps connected with leak flow in bottom-core structure of experimental very high-temperature gas-cooled reactor

    International Nuclear Information System (INIS)

    Kikuchi, Kenji; Futakawa, Masatoshi; Takizuka, Takakazu; Kaburaki, Hideo; Sanokawa, Konomo

    1984-01-01

    In order to minimize the leak flow rate of an experimental VHTR (a multi-purpose very high-temperature gas-cooled reactor), the graphite blocks are tightened to reduce the gap distance between blocks by core restrainers surrounded outside of the fixed reflectors of the bottom-core structure and seal elements are placed in the gaps. By using a 1/2.75-scale model of the bottom-core structure, the experiments on the following items have been carried out: a relationship between core restraint force and block gap, a relationship between core restraint force and inclined angle of the model, leak flow characteristics of seal elements etc. The conclusions derived from the experiments are as follows: (1) Core restraint force is significantly effective for decreasing the gap distance between hot plenum blocks, but ineffective for the gap between hot plenum block and fixed reflector. (2) Graphite seal element reduces the leak flow rate from the top surface of hot plenum block into plenum region to one-third. (author)

  1. Leak testing requirements at a research facility

    International Nuclear Information System (INIS)

    Conner, J.B.

    1979-01-01

    Since September, 1952, Lawrence Livermore Laboratory has conducted pioneering research in applied science. A vital part of this activity has been the development of a variety of high vacuum and ultrahigh vacuum systems. Leaks occur in everything, including vacuum systems. The mass spectrometer leak detection equipment is described

  2. Capacitive system detects and locates fluid leaks

    Science.gov (United States)

    1966-01-01

    Electronic monitoring system automatically detects and locates minute leaks in seams of large fluid storage tanks and pipelines covered with thermal insulation. The system uses a capacitive tape-sensing element that is adhesively bonded over seams where fluid leaks are likely to occur.

  3. Technical basis for inner container leak detection sensitivity goals in 3013 DE surveillance

    Energy Technology Data Exchange (ETDEWEB)

    Berg, John M. [Los Alamos National Lab. (LANL), Los Alamos, NM (United States)

    2017-08-11

    Helium leak checking of 3013 inner container lids is under consideration for addition to DE Surveillance tasks as an improved means to detect any through-wall flaws that may have formed during storage. This white paper evaluates whether leak checking at DE could replace and improve upon the current method of comparing gas compositions and pressures within the inner and outer containers. We have used viscous and molecular flow equations in ANSI N14.5 to calculate what the measured standard helium leak rate would be for hypothetical leaks of three different sizes. For comparison, we have also calculated the effects on gas composition and pressure differences as a function of pre-DE storage time for the same three leak sizes, using molecular and viscous flow equations as well as diffusion equations to predict the relevant gas transport. For a hypothetical leak that would be measured at 1x10-7 std cc/sec, likely an achievable sensitivity using helium leak checking at DE, the calculations predict no measurable effect on pressure difference or gas composition as measured by DE gas analysis. We also calculate that it would take over 200 years for water vapor to diffuse through a 10-7 std cc/sec leak enough to raise the RH outer container to half the RH value in the inner container. A leak 100 times larger, which would be measured at 1x10-5 std cc/sec, the same water vapor diffusion would take at least 14 years. Our conclusion is that helium leak checking will be useful even at a sensitivity of 1x10-5 std cc/sec, and a significant improvement over current DE methods at a sensitivity of 1x10-7 std cc/sec.

  4. Leak detector of liquid sodium

    International Nuclear Information System (INIS)

    Himeno, Yoshiaki.

    1975-01-01

    Object: To arrange a cable core connected to a leakage current detector on the outer wall of piping for liquid sodium, devices or the like and apply a voltage to said core and outer wall to quickly and securely detect the leakage of liquid sodium. Structure: A cable, which is composed of metal coating formed of metal material (copper, steel, stainless, etc.) which is apt to be corroded by reaction products of liquid sodium with water and oxygen in air, and metal oxide (such as magnesium oxide, beryllium oxide, aluminum oxide) as an electric insulator is arranged on the outer wall of pipes or devices. In the event sodium is leaked from the pipes or devices, said metal coating and the insulator are corroded, and the leakage of sodium is sensed by a leakage current detector through the core in the cable. (Kamimura, M.)

  5. Leak detection for underground storage tanks

    International Nuclear Information System (INIS)

    Durgin, P.B.; Young, T.M.

    1993-01-01

    This symposium was held in New Orleans, Louisiana on January 29, 1992. The purpose of this conference was to provide a forum for exchange of state-of-the-art information on leak detection for underground storage tanks that leaked fuel. A widespread concern was protection of groundwater supplies from these leaking tanks. In some cases, the papers report on research that was conducted two or three years ago but has never been adequately directed to the underground storage tank leak-detection audience. In other cases, the papers report on the latest leak-detection research. The symposium was divided into four sessions that were entitled: Internal Monitoring; External Monitoring; Regulations and Standards; and Site and Risk Evaluation. Individual papers have been cataloged separately for inclusion in the appropriate data bases

  6. SCTI chemical leak detection test plan

    International Nuclear Information System (INIS)

    1981-01-01

    Tests will be conducted on the CRBRP prototype steam generator at SCTI to determine the effects of steam generator geometry on the response of the CRBRP chemical leak detection system to small water-to-sodium leaks in various regions of the steam generator. Specifically, small injections of hydrogen gas (simulating water leaks) will be made near the two tubesheets, and the effective transport times to the main stream exit and vent line hydrogen meters will be measured. The magnitude and time characteristics of the meters' response will also be measured. This information will be used by the Small Leak Protection Base Program (SG027) for improved predictions of meter response times and leak detection sensitivity

  7. A mathematical model for leak location and leak area determination in pipeline networks

    Directory of Open Access Journals (Sweden)

    Oyedokun O.I.

    2013-01-01

    Full Text Available Prompt leak location and leak area determination in oil and gas pipeline installations is an indispensable approach to controlling petroleum products wastages in pipes. However, there is an evident lack of literature information on this subject. In this paper, we modelled leak location detection and leak area determination in pipes by applying two methodologies and gave an illustrative example using simulated data with the aid of Matlab. A comparison of these two approaches resulted in an error of 6.24%, suggesting that the closer the leak is to the measurement station, the lower will be the time interval between two successive waves that will pass through the leak and get to the measurement station. The relationship between the pipe area and coefficient of reflection is parabolic. This contribution is valuable to pipeline engineers in the economic control of leaks.

  8. Ultrasonic Detectors Safely Identify Dangerous, Costly Leaks

    Science.gov (United States)

    2013-01-01

    In 1990, NASA grounded its space shuttle fleet. The reason: leaks detected in the hydrogen fuel systems of the Space Shuttles Atlantis and Columbia. Unless the sources of the leaks could be identified and fixed, the shuttles would not be safe to fly. To help locate the existing leaks and check for others, Kennedy Space Center engineers used portable ultrasonic detectors to scan the fuel systems. As a gas or liquid escapes from a leak, the resulting turbulence creates ultrasonic noise, explains Gary Mohr, president of Elmsford, New York-based UE Systems Inc., a long-time leader in ultrasonic detector technologies. "In lay terms, the leak is like a dog whistle, and the detector is like the dog ear." Because the ultrasound emissions from a leak are highly localized, they can be used not only to identify the presence of a leak but also to help pinpoint a leak s location. The NASA engineers employed UE s detectors to examine the shuttle fuel tanks and solid rocket boosters, but encountered difficulty with the devices limited range-certain areas of the shuttle proved difficult or unsafe to scan up close. To remedy the problem, the engineers created a long-range attachment for the detectors, similar to "a zoom lens on a camera," Mohr says. "If you are on the ground, and the leak is 50 feet away, the detector would now give you the same impression as if you were only 25 feet away." The enhancement also had the effect of reducing background noise, allowing for a clearer, more precise detection of a leak s location.

  9. Frequencies of leaks and probability of ignition sources in the H-area tank farm

    International Nuclear Information System (INIS)

    Cramer, D.S.

    1994-01-01

    Point estimates are developed for the probability of an ignition source for tetraphenylborate (TPB) solids in H-area which leak into the annulus of Tank 48 and/or in the Filter Cell. Additionally, leak frequencies and leak rates are estimated for: the inner cell wall of Tank 48; Hanford connectors and single-wall transfer lines in the Filter Cell of the In-Tank Precipitation (ITP) Facility; and the double-wall transfer lines between tank 48, the Filter Cell, Tank 49 and the 'Late Wash' Tank

  10. Design of sealing arrangements for development of leak tight articulated manipulator for waste management and reprocessing plants

    International Nuclear Information System (INIS)

    Patil, Satish B.; Mudaiya, Avinash K.

    2016-01-01

    As a part of development of Remote handling equipment and gadgets, Leak tight Articulated Manipulator (ARTM) has been developed for shielded facilities of Nuclear Recycle Plant. The ARTM is a Master Slave Manipulator having 8 Kg Payload capacity and most suitable for shielded sampling cubicles of Waste Management plants and dilution hot cells of Reprocessing plants. All the motions and forces are transmitted from Master to slave arm through the mechanical linkages, which are housed inside the wall tube. The mechanical linkages and wall tube run across the shielded wall. The applications involving seal tightness of the glove boxes and dilution hot cells intend to use all the accessories including MSMs to be leak tight. During the design of leak tight ARTM, all the potential leak paths through the components of existing ARTM were examined critically and static and dynamic seals were designed based on the geometry and requirement of particular leak path. A leak proof testing set up was fabricated for evaluating the leak rates across the manipulator contemplating the actual operating conditions. The manipulator was subjected to the Friction, Rigidity and Leak tests. The results of the tests are satisfactory and as per the International standards available. The leak rates measured for different manipulators were in the range of 0.05 to 0.1 % of air volume/hr @ 200 mm of water columndifferential negative pressure. (author)

  11. Aerosol penetration through capillaries and leaks: experimental studies on the influence of pressure

    International Nuclear Information System (INIS)

    Morton, D.A.V.; Mitchell, J.P.

    1995-01-01

    It is important to understand the movement of aerosols through ultrafine leak-paths with dimensions of similar order to the gas-borne particles when assessing the validity of leak-testing procedures for transport containers for radioactive materials. Experiments have been undertaken to investigate the penetration of micron-sized airborne particles using glass micro-capillaries as model leak-paths. Previous studies demonstrated a simple relationship between air leakage and total particle penetration rates at a constant driving pressure (100 kPa). The present work has demonstrated the importance of pressure in regulating the rate at which the leak-path is plugged by deposited particles. Much of this deposition appears to take place at the entrances of the capillaries where the air-flow converges. (author)

  12. Imaging review of cerebrospinal fluid leaks.

    Science.gov (United States)

    Vemuri, Naga V; Karanam, Lakshmi S P; Manchikanti, Venkatesh; Dandamudi, Srinivas; Puvvada, Sampath K; Vemuri, Vineet K

    2017-01-01

    Cerebrospinal fluid (CSF) leak occurs due to a defect in the dura and skull base. Trauma remains the most common cause of CSF leak; however, a significant number of cases are iatrogenic, and result from a complication of functional endoscopic sinus surgery (FESS). Early diagnosis of CSF leak is of paramount importance to prevent life-threatening complications such as brain abscess and meningitis. Imaging plays a crucial role in the detection and characterization of CSF leaks. Three-dimensional, isotropic, high resolution computed tomography (HRCT) accurately detects the site and size of the bony defect. CT cisternography, though invasive, helps accurately identify the site of CSF leak, especially in the presence of multiple bony defects. Magnetic resonance imaging (MRI) accurately detects CSF leaks and associated complications such as the encephaloceles and meningoceles. In this review, we emphasize the importance and usefulness of 3D T2 DRIVE MR cisternography in localizing CSF leaks. This sequence has the advantages of effective bone and fat suppression, decreased artefacts, faster acquisition times, three-dimensional capability, y and high spatial resolution in addition to providing very bright signal from the CSF.

  13. Imaging review of cerebrospinal fluid leaks

    Directory of Open Access Journals (Sweden)

    Naga V Vemuri

    2017-01-01

    Full Text Available Cerebrospinal fluid (CSF leak occurs due to a defect in the dura and skull base. Trauma remains the most common cause of CSF leak; however, a significant number of cases are iatrogenic, and result from a complication of functional endoscopic sinus surgery (FESS. Early diagnosis of CSF leak is of paramount importance to prevent life-threatening complications such as brain abscess and meningitis. Imaging plays a crucial role in the detection and characterization of CSF leaks. Three-dimensional, isotropic, high resolution computed tomography (HRCT accurately detects the site and size of the bony defect. CT cisternography, though invasive, helps accurately identify the site of CSF leak, especially in the presence of multiple bony defects. Magnetic resonance imaging (MRI accurately detects CSF leaks and associated complications such as the encephaloceles and meningoceles. In this review, we emphasize the importance and usefulness of 3D T2 DRIVE MR cisternography in localizing CSF leaks. This sequence has the advantages of effective bone and fat suppression, decreased artefacts, faster acquisition times, three-dimensional capability, y and high spatial resolution in addition to providing very bright signal from the CSF.

  14. Successful Endoscopic Therapy of Traumatic Bile Leaks

    Directory of Open Access Journals (Sweden)

    Matthew P. Spinn

    2013-02-01

    Full Text Available Traumatic bile leaks often result in high morbidity and prolonged hospital stay that requires multimodality management. Data on endoscopic management of traumatic bile leaks are scarce. Our study objective was to evaluate the efficacy of the endoscopic management of a traumatic bile leak. We performed a retrospective case review of patients who were referred for endoscopic retrograde cholangiopancreatography (ERCP after traumatic bile duct injury secondary to blunt (motor vehicle accident or penetrating (gunshot trauma for management of bile leaks at our tertiary academic referral center. Fourteen patients underwent ERCP for the management of a traumatic bile leak over a 5-year period. The etiology included blunt trauma from motor vehicle accident in 8 patients, motorcycle accident in 3 patients and penetrating injury from a gunshot wound in 3 patients. Liver injuries were grade III in 1 patient, grade IV in 10 patients, and grade V in 3 patients. All patients were treated by biliary stent placement, and the outcome was successful in 14 of 14 cases (100%. The mean duration of follow-up was 85.6 days (range 54-175 days. There were no ERCP-related complications. In our case review, endoscopic management with endobiliary stent placement was found to be successful and resulted in resolution of the bile leak in all 14 patients. Based on our study results, ERCP should be considered as first-line therapy in the management of traumatic bile leaks.

  15. Pipeline leak detection using volatile tracers

    International Nuclear Information System (INIS)

    Thompson, G.M.; Golding, R.D.

    1993-01-01

    A method of leak detection for underground storage tanks and pipelines adds volatile tracers to the products in the tanks and analyzes the surrounding shallow soil gases for tracer vapors. This method has several advantages: the success of the test is not limited by the size and structural design of the vessels, tanks can be tested at any fill level without taking the tank out of service, the location of a leak along a pipeline is clearly marked by the location of the tracer, and liquid leaks as small as 0.2 liters per hour (lph) can be detected. A limitation is: the backfill material must have some degree of air permeability in the zone above the water table. Several field tests document the success achieved using this method. A tracer leak detection system was installed at Homestead AFB after several other testing methods failed to locate a leak at a valve pit location along approximately 4 kilometers of fuel transfer piping. The leak was detected to the side of the valve pit at a depth of approximately 2.5 meters below the ground surface. Another installation of Edwards AFB involved the collection of 415 soil gas samples along approximately 3,050 meters of 15.25-centimeter fiberglass pipeline. Fourteen separate leaks were detected

  16. Vacuum leak test technique of JT-60

    International Nuclear Information System (INIS)

    Kaminaga, Atsushi; Arai, Takashi; Kodama, Kozo; Sasaki, Noboru; Saidoh, Masahiro

    1998-01-01

    Since a vacuum vessel of JT-60 is very large (167 m 3 ) and is combined with many components, such as magnetic coils, neutral beam injection systems and RF heating systems, etc., the position of leak testing exceeds 700. The two kind of techniques for vacuum leak test used in JT-60 has been described. Firstly the probe helium gas can be fed remotely in the three-dimensionally sectioned 54 regions of the JT-60 torus. The leak test was very rapidly performed by using this method. Secondly the helium detector system has been modified by the additional installation of the cryopump, which reduced the background level of the deuterium gas. The sensitivity of vacuum leak test with the cryopump was two orders of magnitude larger than that of without it. The examples of the performed vacuum leak test are stated. The vacuum leaks during experiments were 9 times. They were caused by thermal strain and plasma discharge. The vacuum leaks just after maintenance are 36 times which mainly caused by mis-installation. (author)

  17. Transient leak detection in crude oil pipelines

    Energy Technology Data Exchange (ETDEWEB)

    Beushausen, R.; Tornow, S.; Borchers, H. [Nord-West Oelleitung, Wilhelmshaven (Germany); Murphy, K.; Zhang, J. [Atmos International Ltd., Manchester (United Kingdom)

    2004-07-01

    Nord-West Oelleitung (NWO) operates 2 crude oil pipelines from Wilhemshaven to Koln and Hamburg respectively. German regulations for transporting flammable substances stipulate that 2 independent continuously working procedures be used to detect leaks. Leak detection pigs are used routinely to complement the surveillance system. This paper described the specific issues of transient leak detection in crude oil pipelines. It was noted that traditional methods have failed to detect leaks that occur immediately after pumps are turned on or off because the pressure wave generated by the transient dominates the pressure wave that results from the leak. Frequent operational changes in a pipeline are often accompanied by an increased number of false alarms and failure to detect leaks due to unsteady operations. NWO therefore decided to have the Atmos statistical pipeline leak detection (SPLD) system installed on their pipelines. The key to the SPLD system is the sequential probability ratio test. Comprehensive data validation is performed following reception of pipeline data from the supervisory control and data acquisition (SCADA) system. The validated data is then used to calculate the corrected flow imbalance, which is fed into the SPRT to determine if there is an increase in the flow imbalance. Pattern recognition is then used to distinguish a leak from operational changes. The SPLD is unique because it uses 3 computational pipeline monitoring methods simultaneously, namely modified volume balance, statistical analysis, and pressure and flow monitoring. The successful installation and testing of the SPLD in 2 crude oil pipelines was described along with the main difficulties associated with transient leaks. Field results were presented for both steady-state and transient conditions. 5 refs., 2 tabs., 16 figs.

  18. Evaluation of Technologies for Retrieval of Waste from Leaking Tanks

    International Nuclear Information System (INIS)

    Bamberger, Judith A.; Hatchell, Brian K.; Lewis, Benjamin E.; Randolph, John D.; Killough, Stephen M.

    2000-01-01

    The US Department of Energy Environmental and Waste Management Tanks Focus Area selected as a strategic initiative the need to identify and develop technologies for remediation of tanks that are known or are suspected to leak. This investigation identified and evaluated technical options for single-shell tank waste retrieval applicable to retrieve waste from potentially leaking tanks. Technologies that minimize leakage use minimal water, and dry retrieval technologies were evaluated. Safety, cost, authorization basis, and schedule risks were identified for each technology to provide River Protection Program with information to evaluate technical and programmatic risk. A workshop was held to identify technology needs and solutions. These approaches grouped into five categories: those related to waste dislodging, waste conveyance, both waste dislodging and conveyance, the deployment platform, and technologies related to leak detection, monitoring, and mitigation. Based on the ranking, six technologies were selected as potential candidates for further evaluation. These items were prioritized into four technologies to recommend for further evaluation (1) Air assisted TORE(R). The TORE(R) produces a processing vortex core with the ability to convey solids at pre-determined slurry concentrations over great distances. The dry TORE(R) concept uses air to develop the vortex to fluidize dry solids. The TORE(R)the solids in a slurry transport line. (2) Sonication for waste dislodging utilizes ultrasonic energy to fracture and dislodge hard waste types such as salt cake and sludge. (3) Novel long-reach manipulators concept is to investigate novel cost effective approaches for long-reach manipulator technology. (4) Next generation crawler technology envisions a non-umbilical dislodger, possibly radio controlled and powered remotely to provide a deployment platform not affected by path, or the need to retrace steps

  19. Analytical and Experimental Studies of Leak Location and Environment Characterization for the International Space Station

    Science.gov (United States)

    Woronowicz, Michael; Abel, Joshua; Autrey, David; Blackmon, Rebecca; Bond, Tim; Brown, Martin; Buffington, Jesse; Cheng, Edward; DeLatte, Danielle; Garcia, Kelvin; hide

    2014-01-01

    The International Space Station program is developing a robotically-operated leak locator tool to be used externally. The tool would consist of a Residual Gas Analyzer for partial pressure measurements and a full range pressure gauge for total pressure measurements. The primary application is to detect NH3 coolant leaks in the ISS thermal control system. An analytical model of leak plume physics is presented that can account for effusive flow as well as plumes produced by sonic orifices and thruster operations. This model is used along with knowledge of typical RGA and full range gauge performance to analyze the expected instrument sensitivity to ISS leaks of various sizes and relative locations ("directionality"). The paper also presents experimental results of leak simulation testing in a large thermal vacuum chamber at NASA Goddard Space Flight Center. This test characterized instrument sensitivity as a function of leak rates ranging from 1 lb-mass/yr. to about 1 lb-mass/day. This data may represent the first measurements collected by an RGA or ion gauge system monitoring off-axis point sources as a function of location and orientation. Test results are compared to the analytical model and used to propose strategies for on-orbit leak location and environment characterization using the proposed instrument while taking into account local ISS conditions and the effects of ram/wake flows and structural shadowing within low Earth orbit.

  20. Analytical and experimental studies of leak location and environment characterization for the international space station

    Energy Technology Data Exchange (ETDEWEB)

    Woronowicz, Michael; Blackmon, Rebecca; Brown, Martin [Stinger Ghaffarian Technologies, Inc, 7701 Greenbelt Rd, Greenbelt, MD 20770 (United States); Abel, Joshua; Hawk, Doug [Alliant Techsystems, Inc, 5050 Powder Mill Road, Beltsville, Maryland 20705 (United States); Autrey, David; Glenn, Jodie [Lockheed Martin, 1300 Hercules, Houston, TX 77058 (United States); Bond, Tim; Buffington, Jesse [NASA Johnson Space Flight Center, 2101 NASA Pkwy, Houston, TX 77058 (United States); Cheng, Edward; Ma, Jonathan; Rossetti, Dino [Conceptual Analytics, 8209 Woburn Abbey Rd, Glenn Dale, MD 20769 (United States); DeLatte, Danielle [ASRC Federal Space and Defense, 7000 Muirkirk Meadows Drive, Suite 100, Beltsville, MD 20705 (United States); Garcia, Kelvin; Mohammed, Jelila; Montt de Garcia, Kristina; Perry, Radford [NASA Goddard Space Flight Center, 8800 Greenbelt Rd, Greenbelt, MD 20771 (United States); Tull, Kimathi [Jackson and Tull, 7375 Executive Pl, Lanham, MD 20706 (United States); Warren, Eric [Wyle STE Group, 1290 Hercules Ave, Houston, TX 77058-2769 (United States)

    2014-12-09

    The International Space Station program is developing a robotically-operated leak locator tool to be used externally. The tool would consist of a Residual Gas Analyzer for partial pressure measurements and a full range pressure gauge for total pressure measurements. The primary application is to demonstrate the ability to detect NH{sub 3} coolant leaks in the ISS thermal control system. An analytical model of leak plume physics is presented that can account for effusive flow as well as plumes produced by sonic orifices and thruster operations. This model is used along with knowledge of typical RGA and full range gauge performance to analyze the expected instrument sensitivity to ISS leaks of various sizes and relative locations (“directionality”). The paper also presents experimental results of leak simulation testing in a large thermal vacuum chamber at NASA Goddard Space Flight Center. This test characterized instrument sensitivity as a function of leak rates ranging from 1 lb{sub m/}/yr. to about 1 lb{sub m}/day. This data may represent the first measurements collected by an RGA or ion gauge system monitoring off-axis point sources as a function of location and orientation. Test results are compared to the analytical model and used to propose strategies for on-orbit leak location and environment characterization using the proposed instrument while taking into account local ISS conditions and the effects of ram/wake flows and structural shadowing within low Earth orbit.

  1. Analytical and experimental studies of leak location and environment characterization for the international space station

    International Nuclear Information System (INIS)

    Woronowicz, Michael; Blackmon, Rebecca; Brown, Martin; Abel, Joshua; Hawk, Doug; Autrey, David; Glenn, Jodie; Bond, Tim; Buffington, Jesse; Cheng, Edward; Ma, Jonathan; Rossetti, Dino; DeLatte, Danielle; Garcia, Kelvin; Mohammed, Jelila; Montt de Garcia, Kristina; Perry, Radford; Tull, Kimathi; Warren, Eric

    2014-01-01

    The International Space Station program is developing a robotically-operated leak locator tool to be used externally. The tool would consist of a Residual Gas Analyzer for partial pressure measurements and a full range pressure gauge for total pressure measurements. The primary application is to demonstrate the ability to detect NH 3 coolant leaks in the ISS thermal control system. An analytical model of leak plume physics is presented that can account for effusive flow as well as plumes produced by sonic orifices and thruster operations. This model is used along with knowledge of typical RGA and full range gauge performance to analyze the expected instrument sensitivity to ISS leaks of various sizes and relative locations (“directionality”). The paper also presents experimental results of leak simulation testing in a large thermal vacuum chamber at NASA Goddard Space Flight Center. This test characterized instrument sensitivity as a function of leak rates ranging from 1 lb m/ /yr. to about 1 lb m /day. This data may represent the first measurements collected by an RGA or ion gauge system monitoring off-axis point sources as a function of location and orientation. Test results are compared to the analytical model and used to propose strategies for on-orbit leak location and environment characterization using the proposed instrument while taking into account local ISS conditions and the effects of ram/wake flows and structural shadowing within low Earth orbit

  2. Leak detection system for RBMK coolant circuit

    International Nuclear Information System (INIS)

    Cherkashov, Ju.M.; Strelkov, B.P.; Korolev, Yu.V.; Eperin, A.P.; Kozlov, E.P.; Belyanin, L.A.; Vanukov, V.N.

    1996-01-01

    In report the description of an object of the control is submitted, requests to control of leak-tightness and functioning of system are formulated, analysis of a current status on NPP with RBMK is submitted, review of methods of the leak-tightness monitoring, their advantage and defects with reference to conditions and features of a design RBMK is indicated, some results of tests and operation of various monitoring methods are submitted, requests on interaction of operative staff, leak-tightness monitoring system and protection system of reactor are submitted. (author). 11 figs, 1 tab

  3. Acoustic leak detector in Monju steam generator

    International Nuclear Information System (INIS)

    Wachi, E.; Inoue, T.

    1990-01-01

    Acoustic leak detectors are equipped with the Monju steam generators for one of the R and D activities, which are the same type of the detectors developed in the PNC 50MW Steam Generator Test Facility. Although they are an additional leak detection system to the regular one in Monju SG, they would also detect the intermediate or large leaks of the SG tube failures. The extrapolation method of a background noise analysis is expected to be verified by Monju SG data. (author). 4 figs

  4. Means for preventing radioactive fluid leaking

    International Nuclear Information System (INIS)

    Akatsu, Jun-ichi.

    1975-01-01

    Object: To permit prevention of leakage of radioactive fluid from line and valve leak sections while also recovering the liquid by producing a vacuum state in a leak-off line by means of a water ejector. Structure: A portion of the water from a condenser is forced by a condensed water pump through a water ejector tank to a recovery tank while controlling an orifice and valve, whereby a vacuum state is produced in the leak-off line to withdraw the leakage fluid. (Kamimura, M.)

  5. Leak detection system for RBMK coolant circuit

    Energy Technology Data Exchange (ETDEWEB)

    Cherkashov, Ju M; Strelkov, B P; Korolev, Yu V; Eperin, A P; Kozlov, E P; Belyanin, L A; Vanukov, V N [Leningrad Nuclear Power Plant, Leningrad (Russian Federation). Research and Development Inst. of Power Engineering

    1997-12-31

    In report the description of an object of the control is submitted, requests to control of leak-tightness and functioning of system are formulated, analysis of a current status on NPP with RBMK is submitted, review of methods of the leak-tightness monitoring, their advantage and defects with reference to conditions and features of a design RBMK is indicated, some results of tests and operation of various monitoring methods are submitted, requests on interaction of operative staff, leak-tightness monitoring system and protection system of reactor are submitted. (author). 11 figs, 1 tab.

  6. Corrosion Evaluation of Tank 40 Leak Detection Box

    Energy Technology Data Exchange (ETDEWEB)

    Mickalonis, J.I.

    1999-07-29

    'Leak detection from the transfer lines in the tank farm has been a concern for many years because of the need to minimize exposure of personnel and contamination of the environment. The leak detection box (LDB) is one line of defense, which must be maintained to meet this objective. The evaluation of a failed LDB was one item from an action plan aimed at minimizing the degradation of LDBs. The Tank 40 LDB, which failed in service, was dug up and shipped to SRTC for evaluation. During a video inspection while in service, this LDB was found to have black tubercles on the interior, which suggested possible microbial involvement. The failure point, however, was believed to have occurred in the drain line from the transfer line jacket. Visual, metallurgical, and biological analyses were performed on the LDB. The analysis results showed that there was not any adverse microbiological growth or significant localized corrosion. The corrosion of the LDB was caused by exposure to aqueous environments and was typical of carbon steel pipes in soil environments.'

  7. The leak microstructure, preliminary results

    International Nuclear Information System (INIS)

    Lombardi, M.

    1997-01-01

    The leak microstructure, a new type of element for position-sensitive proportional gas counter, is introduced. For every single detected ionizing radiation it gives a pair of ''induced'' charges of the same quantity (pulses of the same amplitude), of opposite sign, with the same collection time and essentially in time coincidence, that are proportional to the collected primary ionization. A gas multiplication up to 1.5 x 10 5 was achieved. The complete absence of insulating materials in the active volume of this microstructure enables to avoid problems of charging-up and makes its behaviour stable and repeatable. By using the charge-pair generated, it allows the development of a position-sensitive detecting board with a two-dimensional read-out. Between the two external surfaces of this board it is possible to insert an intermediate third conducting layer which reduces (or practically suppresses) the capacitive cross-talk between the X and Y read-out strip systems. Furthermore, this intermediate layer can give a very fast trigger to coordinate the charge-pair and to govern the data acquisition system. By reading every strip separately it is possible to resolve the multi hit problem in two-dimensions. Using isobutane as the gas, an energy resolution of about 8% FWHM was recorded with α-particles from an 241 Am source. In isobutane gas, X-rays from a 55 Fe source and β-particles from a 14 C source were also detected. (orig.)

  8. Preliminary study of the use of radiotracers for leak detection in industrial applications

    International Nuclear Information System (INIS)

    Wetchagarun, S; Petchrak, A; Tippayakul, C

    2015-01-01

    One of the most widespread uses of radiotracers in the industrial applications is the leak detection of the systems. This technique can be applied, for example, to detect leak in heat exchangers or along buried industrial pipelines. The ability to perform online investigation is one of the most important advantages of the radiotracer technique over other non-radioactive leak detection methods. In this paper, a preliminary study of the leak detection using radiotracer in the laboratory scale was presented. Br-82 was selected for this work due to its chemical property, its suitable half-life and its on-site availability. The NH 4 Br in the form of aqueous solution was injected into the experimental system as the radiotracer. Three NaI detectors were placed along the pipelines to measure system flow rate and to detect the leakage from the piping system. The results obtained from the radiotracer technique were compared to those measured by other methods. It is found that the flow rate obtained from the radiotracer technique agreed well with the one obtained from the flow meter. The leak rate result, however, showed discrepancy between results obtained from two different measuring methods indicating further study on leak detection was required before applying this technique in the industrial system. (paper)

  9. Time-dependent leak behavior of flawed Alloy 600 tube specimens at constant pressure

    Energy Technology Data Exchange (ETDEWEB)

    Bahn, Chi Bum, E-mail: bahn@anl.gov [Argonne National Laboratory, Argonne, IL 60439 (United States); Majumdar, Saurin [Argonne National Laboratory, Argonne, IL 60439 (United States); Harris, Charles [United States Nuclear Regulatory Commission, Rockville, MD 20852 (United States)

    2011-10-15

    Leak rate testing has been performed using Alloy 600 tube specimens with throughwall flaws. Some specimens have shown time-dependent leak behavior at constant pressure conditions. Fractographic characterization was performed to identify the time-dependent crack growth mechanism. The fracture surface of the specimens showed the typical features of ductile fracture, as well as the distinct crystallographic facets, typical of fatigue crack growth at low {Delta}K level. Structural vibration appears to have been caused by the oscillation of pressure, induced by a high-pressure pump used in a test facility, and by the water jet/tube structure interaction. Analyses of the leak behaviors and crack growth indicated that both the high-pressure pump and the water jet could significantly contribute to fatigue crack growth. To determine whether the fatigue crack growth during the leak testing can occur solely by the water jet effect, leak rate tests at constant pressure without the high-pressure pump need to be performed. - Highlights: > Leak rate of flawed Alloy 600 tubing increased at constant pressure condition. > Fractography revealed two cases: ductile tearing and crystallographic facets. > Crystallographic facets are typical features of fatigue crack growth at low {Delta}K. > Fatigue source could be water jet-induced vibration and/or high-pressure pump pulsation.

  10. Preliminary study of the use of radiotracers for leak detection in industrial applications

    Science.gov (United States)

    Wetchagarun, S.; Petchrak, A.; Tippayakul, C.

    2015-05-01

    One of the most widespread uses of radiotracers in the industrial applications is the leak detection of the systems. This technique can be applied, for example, to detect leak in heat exchangers or along buried industrial pipelines. The ability to perform online investigation is one of the most important advantages of the radiotracer technique over other non-radioactive leak detection methods. In this paper, a preliminary study of the leak detection using radiotracer in the laboratory scale was presented. Br-82 was selected for this work due to its chemical property, its suitable half-life and its on-site availability. The NH4Br in the form of aqueous solution was injected into the experimental system as the radiotracer. Three NaI detectors were placed along the pipelines to measure system flow rate and to detect the leakage from the piping system. The results obtained from the radiotracer technique were compared to those measured by other methods. It is found that the flow rate obtained from the radiotracer technique agreed well with the one obtained from the flow meter. The leak rate result, however, showed discrepancy between results obtained from two different measuring methods indicating further study on leak detection was required before applying this technique in the industrial system.

  11. Leak detection in pipelines through spectral analysis of pressure signals

    Directory of Open Access Journals (Sweden)

    Souza A.L.

    2000-01-01

    Full Text Available The development and test of a technique for leak detection in pipelines is presented. The technique is based on the spectral analysis of pressure signals measured in pipeline sections where the formation of stationary waves is favoured, allowing leakage detection during the start/stop of pumps. Experimental tests were performed in a 1250 m long pipeline for various operational conditions of the pipeline (liquid flow rate and leakage configuration. Pressure transients were obtained by four transducers connected to a PC computer. The obtained results show that the spectral analysis of pressure transients, together with the knowledge of reflection points provide a simple and efficient way of identifying leaks during the start/stop of pumps in pipelines.

  12. Endoscopic management of bile leaks after laparoscopic ...

    African Journals Online (AJOL)

    Endoscopic management of bile leaks after laparoscopic cholecystectomy. ... endoscopic management at a median of 12 days (range 2 - 104 days) after surgery. Presenting features included intra-abdominal collections with pain in 58 cases ...

  13. The new CSA standard for leak detection

    Energy Technology Data Exchange (ETDEWEB)

    Pietsch, Ulli [TAU, Edmonton, Alberta, (Canada); Scott, Don [TransCanada Pipelines, Edmonton, Alberta, (Canada)

    2010-07-01

    Standards need to be updated regularly to reflect current technology and industry practices. This paper describes the new Canadian Standards Association (CSA) for leak detection called Recommended Practice for Liquid Hydrocarbon Pipeline System Leak Detection, Annex E, which can be found in the CSA Z662 Oil and Gas Pipeline Systems standard. The CSA formed a task force of industry experts and regulators for a period of 18 months to draft the new standards. Several comparisons were made with the American Petroleum Institute (API) recommended practice API 1130. This new version introduces and defines the terms, critical instrument, critical process and dependent instrument. The most significant improvement made by the new Annex E is the new requirement that an operating company must develop a leak detection strategy. The writing of a leak detection manual is given high priority. The use of both Annex E and API 1130 is recommended.

  14. Leak Detectives Saving Money, Water in Virginia

    Science.gov (United States)

    “Circuit riders” from the Virginia Rural Water Association (VRWA) are traveling to small communities across the Commonwealth using special equipment financed by EPA to locate expensive and wasteful leaks in drinking water distribution systems.

  15. Acoustic leak detection in piping systems, 4

    International Nuclear Information System (INIS)

    Kitajima, Akira; Naohara, Nobuyuki; Aihara, Akihiko

    1983-01-01

    To monitor a high-pressure piping of nuclear power plants, a possibility of acoustic leak detection method has been experimentally studied in practical field tests and laboratory tests. Characteristics of background noise in field test and the results of experiment are summarized as follows: (1) The level of background noise in primary loop (PWR) was almost constant under actual plant operation. But it is possible that it rises at the condition of the pressure in primary loop. (2) Based on many experience of laboratory tests and practical field tests. The leak monitoring system for practical field was designed and developed. To improve the reliability, a judgment of leak on this system is used three factors of noise level, duration time of phenomena and frequency spectrum of noise signal emitted from the leak point. (author)

  16. Acoustic leak detection in nuclear power plants

    International Nuclear Information System (INIS)

    McElroy, J.W.

    1986-01-01

    For several years now, utilities have been utilizing acoustic leak detection methods as an operating tool in their nuclear power stations. The purpose for using the leak detection system at the various stations vary from safety, ALARA, improved operations, preventive maintenance, or increased plant availability. This paper describes the various acoustic techniques and their application. The techniques are divided into three categories: specific component leakage, intersystem leakage, and pipe through-wall crack leakage. The paper addresses each category in terms of motivation to monitor, method of application and operation, and benefits to be gained. Current requirements are reviewed and analyzed with respect to the acoustic techniques. The paper shows how acoustic leak detection is one of the most effective leak detection tools available. 9 figures, 1 table

  17. Leaking Underground Storage Tank Sites in Iowa

    Data.gov (United States)

    Iowa State University GIS Support and Research Facility — Leaking Underground Storage Tank (LUST) sites where petroleum contamination has been found. There may be more than one LUST site per UST site.

  18. Cable-Based Water Leak Detection Technology

    OpenAIRE

    ECT Team, Purdue

    2007-01-01

    Water leaks can be considered as a serious problem from many sources such as water supply and return chains, air conditioning units, cold-water chillers, clogged drains, damaged skylights or windows, or even construction errors. The new water leak detection technologies can provide significant advantages in cost, reliability, and easy adoption have continued since the traditional technology mainly focusing on a spot detector revealed several limitations.

  19. Leak of draft report on radioactive waste

    International Nuclear Information System (INIS)

    1986-01-01

    The Environment Committee's second report discusses the leak of the draft report on radioactive waste. The circumstances of the leak are discussed and ''The Times'' and ''The Guardian'' articles of December 1985 are printed in full, as are the letter from the Chairman of the environmental committee to the members and their replies. The letters from Mr John Large of Large and Associates to the Chairman of the Environment Committee, and Mr Large's correspondence with Greenpeace are also printed. (UK)

  20. Leak detection systems for VVER units based on leak before break concept. PowerPoint presentation

    International Nuclear Information System (INIS)

    Matal, Oldrich

    2010-01-01

    To comply with international standards, independent leak monitoring systems should be installed based on the monitoring of different physical parameters capable of detecting any small leak within one hour from the start of the leak. Such leak detection systems are based mainly on acoustic emission monitoring, humidity monitoring and/or radiation monitoring. Advanced systems integrate the monitoring of different physical parameters into one integrated leak detection system. The Integrated Leak Detection System (ILDS) for NPP Metsamor is described. This system consists of three independent leak detection subsystems, viz. LEMOP (LEak MOnitoring of Pipelines) based on acoustic emission monitoring, HUMOS (HUmidity MOnitoring System) based on humidity monitoring, and RAMOS (RAdiation MOnitoring System) based on radiation monitoring). The Integrated Leak Detection System (ILDS) collects data from the three systems, performs data evaluation, data storage, generates alarms and provides a user interface for the whole system including all subsystems. An example of DiagAssist user interface in the ILDS system in the pictorial form. (P.A.)

  1. Wireless sensor network for sodium leak detection

    International Nuclear Information System (INIS)

    Satya Murty, S.A.V.; Raj, Baldev; Sivalingam, Krishna M.; Ebenezer, Jemimah; Chandran, T.; Shanmugavel, M.; Rajan, K.K.

    2012-01-01

    Highlights: ► Early detection of sodium leak is mandatory in any reactor handling liquid sodium. ► Wireless sensor networking technology has been introduced for detecting sodium leak. ► We designed and developed a wireless sensor node in-house. ► We deployed a pilot wireless sensor network for handling nine sodium leak signals. - Abstract: To study the mechanical properties of Prototype Fast Breeder Reactor component materials under the influence of sodium, the IN Sodium Test (INSOT) facility has been erected and commissioned at Indira Gandhi Centre for Atomic Research. Sodium reacts violently with air/moisture leading to fire. Hence early detection of sodium leak if any is mandatory for such plants and almost 140 sodium leak detectors are placed throughout the loop. All these detectors are wired to the control room for data collection and monitoring. To reduce the cost, space and maintenance that are involved in cabling, the wireless sensor networking technology has been introduced in the sodium leak detection system of INSOT. This paper describes about the deployment details of the pilot wireless sensor network and the measures taken for the successful deployment.

  2. Helium leak testing of scanning electron microscope

    International Nuclear Information System (INIS)

    Ahmad, Anis; Tripathi, S.K.; Mukherjee, D.

    2015-01-01

    Scanning Electron Microscope (SEM) is a specialized electron-optical device which is used for imaging of miniscule features on topography of material specimens. Conventional SEMs used finely focused high energy (about 30 KeV) electron beam probes of diameter of about 10nm for imaging of solid conducting specimens. Vacuum of the order of 10"-"5 Torr is prerequisite for conventional Tungsten filament type SEMs. One such SEM was received from one of our laboratory in BARC with a major leak owing to persisting poor vacuum condition despite continuous pumping for several hours. He-Leak Detection of the SEM was carried out at AFD using vacuum spray Technique and various potential leak joints numbering more than fifty were helium leak tested. The major leak was detected in the TMP damper bellow. The part was later replaced and the repeat helium leak testing of the system was carried out using vacuum spray technique. The vacuum in SEM is achieved is better than 10"-"5 torr and system is now working satisfactorily. (author)

  3. Leak detector for reactor pressure vessel

    International Nuclear Information System (INIS)

    Morimoto, Mikio.

    1991-01-01

    A branched pipe is disposed to a leak off pipeline led from a flange surface which connects the main body and the upper lid of a reactor pressure vessel. An exhaust pump is disposed to the branched pipe and a moisture gage is disposed on the side of the exhaustion and a dry air supplier is connected to the branched pipe. Upon conducting a pressure-proof leak test for the reactor pressure vessel, the exhaust pump is operated and an electromagnet valve disposed at the upstream of the dry air supplier is opened and closed repeatedly. The humidity of air sucked by the exhaust pump is detected by the moisture gage. If leaks should be caused in the joining surface of the flange, leaked water is diffused as steams. Accordingly, occurrence of leak can be detected instantly based on the comparison with the moisture level of the dry air as a standard. In this way, a leak test can be conducted reliably in a short period of time with no change of for the reactor pressure container itself. (I.N.)

  4. 40 CFR 63.424 - Standards: Equipment leaks.

    Science.gov (United States)

    2010-07-01

    ....424 Standards: Equipment leaks. (a) Each owner or operator of a bulk gasoline terminal or pipeline... location of all equipment in gasoline service at the facility. (c) Each detection of a liquid or vapor leak... replacement of leaking equipment shall be completed within 15 calendar days after detection of each leak...

  5. Small leak shutdown, location, and behavior in LMFBR steam generators

    International Nuclear Information System (INIS)

    Sandusky, D.W.

    1976-01-01

    The paper summarizes an experimental study of small leaks tested under LMFBR steam generator conditions. Defected tubes were exposed to flowing sodium and steam. The observed behavior of the defected tubes is reported along with test results of shutdown methods. Leak location methods were investigated. Methods were identified to open plugged defects for helium leak testing and detect plugged leaks by nondestructive testing

  6. 40 CFR 86.328-79 - Leak checks.

    Science.gov (United States)

    2010-07-01

    ... 40 Protection of Environment 18 2010-07-01 2010-07-01 false Leak checks. 86.328-79 Section 86.328... Gasoline-Fueled and Diesel-Fueled Heavy-Duty Engines; Gaseous Exhaust Test Procedures § 86.328-79 Leak checks. (a) Vacuum side leak check. (1) Any location within the analysis system where a vacuum leak could...

  7. AIRBORNE, OPTICAL REMOTE SENSNG OF METHANE AND ETHANE FOR NATURAL GAS PIPELINE LEAK DETECTION

    Energy Technology Data Exchange (ETDEWEB)

    Jerry Myers

    2005-04-15

    Ophir Corporation was awarded a contract by the U. S. Department of Energy, National Energy Technology Laboratory under the Project Title ''Airborne, Optical Remote Sensing of Methane and Ethane for Natural Gas Pipeline Leak Detection'' on October 14, 2002. The scope of the work involved designing and developing an airborne, optical remote sensor capable of sensing methane and, if possible, ethane for the detection of natural gas pipeline leaks. Flight testing using a custom dual wavelength, high power fiber amplifier was initiated in February 2005. Ophir successfully demonstrated the airborne system, showing that it was capable of discerning small amounts of methane from a simulated pipeline leak. Leak rates as low as 150 standard cubic feet per hour (scf/h) were detected by the airborne sensor.

  8. Raman distributed sensor system for temperature monitoring and leak detection in sodium circuits of FBR

    Energy Technology Data Exchange (ETDEWEB)

    Pandian, C.; Kasinathan, M.; Sosamma, S.; Babu Rao, C.; Jayakumar, T.; Murali, N.; Paunikar, V.; Kumar, S.; Rajan, K. K.; Raj, B. [Indira Gandhi Centre for Atomic Research, Kalpakkam (India)

    2009-07-01

    Leak detection in coolant loops of nuclear reactors is critical for the safety and performance of the reactors. The feasibility of using Raman distributed temperature sensor (RDTS) has been studied on a 30 m test loop. Temperature in sodium circuits of fast Breeder Reactor (FBR) exceeds 550 C degrees, gold coated fiber is chosen as sensor fibers. Leak is simulated through an artificial micro fissure integrated in the test loop with provision for controlled leak rate. The results are discussed in the paper. The temperature response of RDTS is compared to the conventional thermocouple and their performance was found comparable. The feasibility of detecting the temperature differential of a controlled leak with RDTS is demonstrated

  9. Leak detection in a high-pressure heat exchanger system in a refinery using radiotracer technique

    International Nuclear Information System (INIS)

    Samantray, J.S.; Sunil Goswami; Sharma, V.K.; Jayashree Biswal; Pant, H.J.

    2014-01-01

    A radiotracer investigation was carried out in a diesel hydrotreater (DHDT) unit in a refinery for leak detection in a breech-lock heat exchanger system. The main objectives of the study were to identify the leaking heat exchanger in a system with six heat exchangers and estimate the leak rate. Bromine-82 as dibromobiphenyl was selected and used as radiotracer for the investigation. The radiotracer was instantaneously injected into the suction end of the feed pump line to the heat exchanger of the DHDT unit. The movement of the tracer was measured at strategically selected locations using NaI(Tl) scintillation detectors. Based upon the results of the radiotracer investigation, it was found that out of six heat exchangers, exchanger E-1F was leaking. (author)

  10. Design of on-line steam generator leak monitoring system based on Cherenkov counting technique

    International Nuclear Information System (INIS)

    Dileep, B.N.; D'Cruz, S.J.; Biju, P.; Jashi, K.B.; Prabhakaran, V.; Venkataramana, K.; Managanvi, S.S.

    2006-01-01

    The methodology developed by Nuclear Power Corporation of India Ltd. for identification of leaky Steam Generator (SG) by monitoring 134 I activity in the blow down water is a very high sensitive method. However, this technique can not be put into use as an on-line system. A new method of on-line detection of SG leak and identify the offending SG based on Cherenkov counting technique is explained in this paper. It identifies the leak by detecting Cherenkov radiation produced by the hard beta emitting radio nuclides escaped into feed water during leak in an operating reactor. A simulated system shows that a leak rate of 2 kg/h can be detected by the proposed system, while coolant 134 I activity is 3.7 MBq/l (100μCi/l). (author)

  11. A study on multi-data source fusion method for petroleum pipeline leak detection

    Energy Technology Data Exchange (ETDEWEB)

    Liang, Wei; Zhang, Laibin [Research Center of Oil and Gas Safety Engineering Technology, China University of Petroleum, Beijing, (China)

    2010-07-01

    The detection of leaks on petroleum pipeline is a very important safety issue. Several studies were commissioned to develop new monitoring procedures for leakage detection. This paper sets out a new leak detection process. The approach developed took into consideration steady and transient states. The study investigated leak diagnosis problems in product pipelines using multi-sensor measurements (pressure, flux, density and temperature). The information collected from each sensor was considered as pieces of evidence that describe the operational conditions of the pipeline. The Dempster-Shafer (D-S) theory is used to associate multi-sensor data to pipe health indices. Experimental pressure and flow rate data were recorded using a Pipeline Leak Detection System (PLDS) acquisition card and used to verify the accuracy and reliability of this new detection method. The results showed that the degree of credibility was a high as 0.877. It was also found that multi-feature information fusion improves recognition of pipeline conditions.

  12. A reweighted ℓ1-minimization based compressed sensing for the spectral estimation of heart rate variability using the unevenly sampled data.

    Directory of Open Access Journals (Sweden)

    Szi-Wen Chen

    Full Text Available In this paper, a reweighted ℓ1-minimization based Compressed Sensing (CS algorithm incorporating the Integral Pulse Frequency Modulation (IPFM model for spectral estimation of HRV is introduced. Knowing as a novel sensing/sampling paradigm, the theory of CS asserts certain signals that are considered sparse or compressible can be possibly reconstructed from substantially fewer measurements than those required by traditional methods. Our study aims to employ a novel reweighted ℓ1-minimization CS method for deriving the spectrum of the modulating signal of IPFM model from incomplete RR measurements for HRV assessments. To evaluate the performance of HRV spectral estimation, a quantitative measure, referred to as the Percent Error Power (PEP that measures the percentage of difference between the true spectrum and the spectrum derived from the incomplete RR dataset, was used. We studied the performance of spectral reconstruction from incomplete simulated and real HRV signals by experimentally truncating a number of RR data accordingly in the top portion, in the bottom portion, and in a random order from the original RR column vector. As a result, for up to 20% data truncation/loss the proposed reweighted ℓ1-minimization CS method produced, on average, 2.34%, 2.27%, and 4.55% PEP in the top, bottom, and random data-truncation cases, respectively, on Autoregressive (AR model derived simulated HRV signals. Similarly, for up to 20% data loss the proposed method produced 5.15%, 4.33%, and 0.39% PEP in the top, bottom, and random data-truncation cases, respectively, on a real HRV database drawn from PhysioNet. Moreover, results generated by a number of intensive numerical experiments all indicated that the reweighted ℓ1-minimization CS method always achieved the most accurate and high-fidelity HRV spectral estimates in every aspect, compared with the ℓ1-minimization based method and Lomb's method used for estimating the spectrum of HRV from

  13. Analysis methods for evaluating leak-before-break in U-tube steam generators

    International Nuclear Information System (INIS)

    Griesbach, T.; Cipolla, R.

    1985-01-01

    In recent years, there has been an increased incidence of cracking in steam generator tubes. As a result, there has been increased effort in assuring that cracks in steam generator tubes will leak well in advance of significant loss in structural integrity. Demonstrating a leak-before-break condition is an integrated analysis process that utilizes several engineering disciplines, specifically, materials engineering, fracture mechanics, stress analysis, and fluid mechanics. The output from a leak-before-break assessment is typically depicted in terms of available margins against failure and measurable or detectable leak rate. In this paper, the analysis methods for performing a leak-before-break analysis for the U-tubes of a recirculating steam generator are presented. The results from generic analysis for the first row U-tubes illustrates the analysis techniques. Because of realistic input values used herein, these results also suggest that large leak rates are possible from cracks in U-bend regions, yet these cracks are small relative to their critical size for failure. Hence, orderly shutdowns can be completed prior to the point when tube bursting is of concern

  14. Development of a portable heavy-water leak sensor based on laser absorption spectroscopy

    International Nuclear Information System (INIS)

    Lee, Lim; Park, Hyunmin; Kim, Taek-Soo; Kim, Minho; Jeong, Do-Young

    2016-01-01

    Highlights: • We developed a compact and portable laser sensor for a detection of heavy water leakage. • The sensor is wearable and also easy to use to search for the leak point. • It is sensitive enough to find invisible very tiny leaks. - Abstract: A compact and portable leak sensor based on cavity enhanced absorption spectroscopy has been newly developed for a detection of heavy water leakage which may happen in the facilities using heavy water such as pressurized heavy water reactor (PHWR). The developed portable sensor is suitable as an individual instrument for the measuring leak rate and finding the leak location because it is sufficiently compact in size and weight and operated by using an internal battery. In the performance test, the minimum detectable leak rate was estimated as 0.05 g/day from the calibration curve. This new sensor is expected to be a reliable and promising device for the detection of heavy water leakage since it has advantages on real-time monitoring and early detection for nuclear safety.

  15. Crack growth of throughwall flaw in Alloy 600 tube during leak testing

    International Nuclear Information System (INIS)

    Bahn, Chi Bum; Majumdar, Saurin

    2015-01-01

    Graphical abstract: - Highlights: • A series of leak testing was conducted at a constant pressure and room temperature. • The time-dependent increase in the leak rate was observed. • The fractography revealed slip offsets and crystallographic facets. • Time-dependent plasticity at the crack tip caused the slip offsets. • Fatigue by jet/structure interaction caused the crystallographic facets. - Abstract: We examined the issue of whether crack growth in a full thickness material can occur in a leaking crack. A series of leak tests was conducted at a room temperature and constant pressure (17.3 MPa) with Alloy 600 tube specimens containing a tight rectangular throughwall axial fatigue crack. To exclude a potential pulsation effect by a high pressure pump, the test water was pressurized by using high pressure nitrogen gas. Fractography showed that crack growth in the full thickness material can occur in the leaking crack by two mechanisms: time-dependent plasticity at the crack tip and fatigue induced by jet/structure interaction. The threshold leak rate at which the jet/structure interaction was triggered was between 1.3 and 3.3 L/min for the specific heat of the Alloy 600 tube tested

  16. Field tests and commercialization of natural gas leak detectors

    Energy Technology Data Exchange (ETDEWEB)

    Choi, D S; Jeon, J S; Kim, K D; Cho, Y A [R and D Center, Korea Gas Corporation, Ansan (Korea)

    1999-09-01

    Objectives - (1) fields test of industrial gas leak detection monitoring system. (2) commericialization of residential gas leak detector. Contents - (1) five sets of gas leak detection monitoring system were installed at natural gas transmition facilities and tested long term stability and their performance. (2) improved residential gas leak detector was commercialised. Expected benefits and application fields - (1) contribution to the improvement of domestic gas sensor technology. (2) localization of fabrication technology for gas leak detectors. 23 refs., 126 figs., 37 tabs.

  17. Capillary leak syndrome: etiologies, pathophysiology, and management.

    Science.gov (United States)

    Siddall, Eric; Khatri, Minesh; Radhakrishnan, Jai

    2017-07-01

    In various human diseases, an increase in capillary permeability to proteins leads to the loss of protein-rich fluid from the intravascular to the interstitial space. Although sepsis is the disease most commonly associated with this phenomenon, many other diseases can lead to a "sepsis-like" syndrome with manifestations of diffuse pitting edema, exudative serous cavity effusions, noncardiogenic pulmonary edema, hypotension, and, in some cases, hypovolemic shock with multiple-organ failure. The term capillary leak syndrome has been used to describe this constellation of disease manifestations associated with an increased capillary permeability to proteins. Diseases other than sepsis that can result in capillary leak syndrome include the idiopathic systemic capillary leak syndrome or Clarkson's disease, engraftment syndrome, differentiation syndrome, the ovarian hyperstimulation syndrome, hemophagocytic lymphohistiocytosis, viral hemorrhagic fevers, autoimmune diseases, snakebite envenomation, and ricin poisoning. Drugs including some interleukins, some monoclonal antibodies, and gemcitabine can also cause capillary leak syndrome. Acute kidney injury is commonly seen in all of these diseases. In addition to hypotension, cytokines are likely to be important in the pathophysiology of acute kidney injury in capillary leak syndrome. Fluid management is a critical part of the treatment of capillary leak syndrome; hypovolemia and hypotension can cause organ injury, whereas capillary leakage of administered fluid can worsen organ edema leading to progressive organ injury. The purpose of this article is to discuss the diseases other than sepsis that produce capillary leak and review their collective pathophysiology and treatment. Copyright © 2017 International Society of Nephrology. Published by Elsevier Inc. All rights reserved.

  18. Differential Impact of Anastomotic Leak in Patients With Stage IV Colonic or Rectal Cancer: A Nationwide Cohort Study.

    Science.gov (United States)

    Nordholm-Carstensen, Andreas; Rolff, Hans Christian; Krarup, Peter-Martin

    2017-05-01

    Anastomotic leak has a negative impact on the prognosis of patients who undergo colorectal cancer resection. However, data on anastomotic leak are limited for stage IV colorectal cancers. The purpose of this study was to investigate the impact of anastomotic leak on survival and the decision to administer chemotherapy and/or metastasectomy after elective surgery for stage IV colorectal cancer. This was a nationwide, retrospective cohort study. Data were obtained from the Danish Colorectal Cancer Group, the Danish Pathology Registry, and the National Patient Registry. Patients who were diagnosed with stage IV colorectal cancer between 2009 and 2013 and underwent elective resection of their primary tumors were included. The primary outcome was all-cause mortality depending on the occurrence of anastomotic leak. Secondary outcomes were the administration of and time to adjuvant chemotherapy, metastasectomy rate, and risk factors for leak. Of the 774 patients with stage IV colorectal cancer who were included, 71 (9.2%) developed anastomotic leaks. Anastomotic leak had a significant impact on the long-term survival of patients with colon cancer (p = 0.04) but not on those with rectal cancer (p = 0.91). Anastomotic leak was followed by the decreased administration of adjuvant chemotherapy in patients with colon cancer (p = 0.007) but not in patients with rectal cancer (p = 0.47). Finally, anastomotic leak had a detrimental impact on metastasectomy rates after colon cancer but not on resection rates of rectal cancer. Retrospective data on the selection criteria for primary tumor resection and metastatic tumor load were unavailable. The impact of anastomotic leak on patients differed between stage IV colon and rectal cancers. Survival and eligibility to receive chemotherapy and metastasectomy differed between patients with colon and rectal cancers. When planning for primary tumor resection, these factors should be considered.

  19. Operational Philosophy Concerning Manned Spacecraft Cabin Leaks

    Science.gov (United States)

    DeSimpelaere, Edward

    2011-01-01

    The last thirty years have seen the Space Shuttle as the prime United States spacecraft for manned spaceflight missions. Many lessons have been learned about spacecraft design and operation throughout these years. Over the next few decades, a large increase of manned spaceflight in the commercial sector is expected. This will result in the exposure of commercial crews and passengers to many of the same risks crews of the Space Shuttle have encountered. One of the more dire situations that can be encountered is the loss of pressure in the habitable volume of the spacecraft during on orbit operations. This is referred to as a cabin leak. This paper seeks to establish a general cabin leak response philosophy with the intent of educating future spacecraft designers and operators. After establishing a relative definition for a cabin leak, the paper covers general descriptions of detection equipment, detection methods, and general operational methods for management of a cabin leak. Subsequently, all these items are addressed from the perspective of the Space Shuttle Program, as this will be of the most value to future spacecraft due to similar operating profiles. Emphasis here is placed upon why and how these methods and philosophies have evolved to meet the Space Shuttle s needs. This includes the core ideas of: considerations of maintaining higher cabin pressures vs. lower cabin pressures, the pros and cons of a system designed to feed the leak with gas from pressurized tanks vs. using pressure suits to protect against lower cabin pressures, timeline and consumables constraints, re-entry considerations with leaks of unknown origin, and the impact the International Space Station (ISS) has had to the standard Space Shuttle cabin leak response philosophy. This last item in itself includes: procedural management differences, hardware considerations, additional capabilities due to the presence of the ISS and its resource, and ISS docking/undocking considerations with a

  20. Innovative Acoustic Sensor Technologies for Leak Detection in Challenging Pipe Types

    Science.gov (United States)

    2016-12-30

    considerably based on region. The electrical costs used in the economic analysis at ERDC is $0.08 per kW-hr and $0.14 per kW-hr (average commercial...5.63 at the $50.37 per hour prevailing wage rate for plumbers. Based on the projected breakeven labor rate analysis , the labor rate could increase...63 Figure 6-10. LeakFinderRT Results for POI Identified at ERDC ..............................................66 Figure 6-11. LeakFinderRT

  1. Use of an autologous liver round ligament flap zeros postoperative bile leak after curative resection of hilar cholangiocarcinoma.

    Science.gov (United States)

    Sun, Da-Xin; Tan, Xiao-Dong; Gao, Feng; Xu, Jin; Cui, Dong-Xu; Dai, Xian-Wei

    2015-01-01

    Postoperative bile leak is a major surgical morbidity after curative resection with hepaticojejunostomy for hilar cholangiocarcinoma, especially in Bismuth-Corlette types III and IV. This retrospective study assessed the effectiveness and safety of an autologous hepatic round ligament flap (AHRLF) for reducing bile leak after hilar hepaticojejunostomy. Nine type III and IV hilar cholangiocarcinoma patients were consecutively hospitalized for elective perihilar partial hepatectomy with hilar hepaticojejunostomy using an AHRLF between October 2009 and September 2013. The AHRLF was harvested to reinforce the perihilar hepaticojejunostomy. Main outcome measures included operative time, blood loss, postoperative recovery times, morbidity, bile leak, R0 resection rate, and overall survival. All patients underwent uneventful R0 resection with hilar hepaticojejunostomy. No patient experienced postoperative bile leak. The AHRLF was associated with lack of bile leak after curative perihilar hepatectomy with hepaticojejunostomy for hilar cholangiocarcinoma, without compromising oncologic safety, and is recommended in selected patients.

  2. A New Concept for an Effective Leak Detection and Loclisation in Multiphase Fluid Pipelines

    Directory of Open Access Journals (Sweden)

    Mahmoud Meribout

    2011-02-01

    Full Text Available The aim of this paper is to present a secure wireless sensor network-based infrastructure for fast and accurate detection of eventual leaks that might occur in multiphase pipelines (i.e., pipelines which carry simultaneously more than one fluid. The system is scalable to monitor long distances of pipelines. It consists of a newly designed low cost pipeline set which is composed of an inner pipe that carries the multiphase fluid, surrounded by a second outer pipe that holds the leak detection unit. This latest comprises an air-ultrasonic sensor which continuously senses the presence of the leak. The location of the leak is determined by a bidirectional microphone. Both these sensors are interfaced to a wireless sensor module which performs control, signal processing, and transmission tasks. Hence, the second contribution of the paper is to provide a new secure and reliable communication protocol that takes into consideration the nature of the network in terms of packets patterns and hardware constraints of the communicating nodes. Online tests in a laboratory scale flow loop indicate that the system is capable to accurately determine the location of the leak and its rate (in l/min in fast response time for different scenarios of leaks.

  3. Steam generators of Phenix: Measurement of the hydrogen concentration in sodium for detecting water leaks in the steam generator tubes

    International Nuclear Information System (INIS)

    Cambillard, E.; Lacroix, A.; Langlois, J.; Viala, J.

    1975-01-01

    The Phenix secondary circuits are provided with measurement systems of hydrogen concentration in sodium, that allow for the detection of possible water leaks in steam generators and the location of a faulty module. A measurement device consists of : a detector with nickel membranes of 0, 3 mm wall thickness, an ion pump with a 200 l/s flow rate, a quadrupole mass spectrometer and a calibrated hydrogen leak. The temperature correction is made automatically. The main tests carried out on the leak detection systems are reported. Since the first system operation (October 24, 1973), the measurements allowed us to obtain the hydrogen diffusion rates through the steam generator tube walls. (author)

  4. Leveraging Social Norms to Improve Leak Resolution Outcomes Across Meter Classes:

    Science.gov (United States)

    Holleran, W.

    2016-12-01

    Over the past decade, utilities, governments, businesses, and nonprofits have come to realize that more than just financial considerations and information drive behavior. Social and psychological factors also play a significant role in shaping consumers' decisions and behaviors around resource use. Stakeholders have consequently turned their interest to behavioral science, a multidisciplinary field that draws from psychology, sociology, public health, and behavioral economics to explain the complex mechanisms that shape human behavior. When used strategically, behavioral science holds the potential to drive down resource use, drive up profits, and generate measurable gains in conservation and efficiency. WaterSmart will present on how the water sector can employ behavioral science to nudge residential rate-payers to use water more efficiently and help them save money. Utilities can use behavioral science to influence people's reaction to leaks. 5% of Single Family Residential (SFR) metered water use can be attributed to leaks. This value potentially skews even higher for MultiFamily (MF) and Commercial accounts given that it can get lost in the noise of daily consumption. Existing leak detection algorithms in the market are not sophisticated enough to detect leaks for a MF or Commercial property. Leveraging data from utilities on known leak events at MF and Commercial buildings allowed WaterSmart to train a machine learning model to identify key features in the load shape and accurately detect these types of water use events. The outcome of the model is a leak amount and confidence level for each irregular usage event. The model also incorporates record feedback from users on the type of leak event, and the accuracy of the alert. When WaterSmart leverages this data model with social norms messaging, we've been able to improve water demand management for MF and Commercial properties. Experiences from leak detection and resolution in the SFR space will also be

  5. Investigations of leak opening and outflow behaviour on straight pipes with circumferential cracks with internal pressure and bending load

    International Nuclear Information System (INIS)

    Grebner, H.; Hoefler, A.; Hunger, H.

    1989-01-01

    The experiments carried out so far on straight pipes with circumferential cracks and results of subsequent calculations from this experiment are introduced. The subsequent calculations are not yet completed at all points. From the experiments one can record that the selected crack sizes and stresses have guaranteed stable crack behaviour in all cases. The comparison of experimental and calculated crack openings shows satisfactory agreement (difference about 20% for experiment E22.03. The compared leak rates show differences of up to about 50% (in isolated cases even more). For small leak rates (0.01 to 0.1 kg/sec), one can expect a difference of about 100% between calculation and experiment. For medium leak rates, we regard a maximum difference of about 30% as achievable. For large leak rates, the achievable accuracy plays no part for the detectability. (orig./DG) [de

  6. Location of leaks in pressurized underground pipelines

    International Nuclear Information System (INIS)

    Eckert, E.G.; Maresca, J.W. Jr.

    1993-01-01

    Millions of underground storage tanks (UST) are used to store petroleum and other chemicals. The pressurized underground pipelines associated with USTs containing petroleum motor fuels are typically 2 in. in diameter and 50 to 200 ft in length. These pipelines typically operate at pressures of 20 to 30 psi. Longer lines, with diameters up to 4 in., are found in some high-volume facilities. There are many systems that can be used to detect leaks in pressurized underground pipelines. When a leak is detected, the first step in the remediation process is to find its location. Passive-acoustic measurements, combined with advanced signal-processing techniques, provide a nondestructive method of leak location that is accurate and relatively simple, and that can be applied to a wide variety of pipelines and pipeline products

  7. Enhanced leak detection risk model development

    Energy Technology Data Exchange (ETDEWEB)

    Harron, Lorna; Barlow, Rick; Farquhar, Ted [Enbridge Pipelines Inc., Edmonton, Alberta (Canada)

    2010-07-01

    Increasing concerns and attention to pipeline safety have engaged pipeline companies and regulatory agencies to extend their approaches to pipeline integrity. The implementation of High Consequence Areas (HCAs) has especially had an impact on the development of integrity management protocols (IMPs) for pipelines. These IMPs can require that a risk based assessment of integrity issues be applied to specific HCA risk factors. This paper addresses the development of an operational risk assessment approach for pipeline leak detection requirements for HCAs. A detailed risk assessment algorithm that includes 25 risk variables and 28 consequence variables was developed for application to all HCA areas. This paper describes the consultative process that was used to workshop the development of this algorithm. Included in this description is how the process addressed various methods of leak detection across a wide variety of pipelines. The paper also looks at development challenges and future steps in applying operation risk assessment techniques to mainline leak detection risk management.

  8. Remote leak detection for the TFTR

    International Nuclear Information System (INIS)

    Walthers, C.R.

    1977-01-01

    The planned design for the TFTR (TOKAMAK Fusion Test Reactor) remote leak detection system consists of a central console which controls the application of tracer gas to possible leak areas. Seals are tested by admitting tracer gas to machined cavities on the atmospheric side of the seal. The tracer gas is brought to the seal cavity by 1 / 8 -inch diameter tubes which connect to local tracer gas/vacuum manifolds located outside the protective radiation shielding. Vacuum shell walls and welds are checked by flowing tracer gas through annular heating/cooling passages. The detector will be either an MSLD (mass spectrometer leak detector) or an RGA (residual gas analyzer), the location of which is not finalized. Feasibility tests performed and planned include response and sensitivity measurements of possible tubing/detector configurations with several tracer gases

  9. Combustion suppressing device for leaked sodium

    International Nuclear Information System (INIS)

    Ooto, Akihiro.

    1985-01-01

    Purpose: To suppress the atmospheric temperature to secure the building safety and shorten the recovery time after the leakage in a chamber for containing sodium leaked from coolant circuit equipments or pipeways of LMFBR type rector by suppressing the combustion of sodium contained in the chamber. Constitution: To the inner wall of a chamber for containing sodium handling equipments, are vertically disposed a panel having a coolant supply port at the upper portion and a coolant discharge port at the lower portion thereof and defined with a coolant flowing channel and a panel for sucking the coolant discharged from the abovementioned panel and exhausting the same externally. Further, a corrugated combustion suppressing plate having apertures for draining the condensated leaked sodium is disposed near the sodium handling equipments. If ruptures are resulted to the sodium handling equipments or pipeway, leaked sodium is passed through the drain apertures in the suppressing plate and stored at the bottom of the containing chamber. (Horiuchi, T.)

  10. Cold Leak Tests of LHC Beam Screens

    CERN Document Server

    Collomb-Patton, C; Jenninger, B; Kos, N

    2009-01-01

    In order to guide the high energy proton beams inside its two 27 km long vacuum rings, the Large Hadron Collider (LHC) at CERN, Geneva, makes use of superconducting technology to create the required magnetic fields. More than 4000 beam screens, cooled at 7 20 K, are inserted inside the 1.9 K beam vacuum tubes to intercept beam induced heat loads and to provide dynamic vacuum stability. As extremely high helium leak tightness is required, all beam screens have been leak tested under cold conditions in a dedicated test stand prior to their installation. After describing the beam screen design and its functions, this report focuses on the cold leak test sequence and discusses the results.

  11. An analysis of main processes at small water-into-sodium leaks in the BN-350 and BN-600 NPP steam generators

    International Nuclear Information System (INIS)

    Poplavsky, V.M.

    1990-01-01

    The paper presents the main characteristics of emergency processes at small water-into-sodium leaks that took place during the BN-350 and BN-600 NPP steam generators operation. Leak characteristics are presented, the relationship between such parameters as leak rate and duration, its location in a tube bundle, mass of water ingress into sodium, and the character and size of a failure in the interaction zone is analyzed. (author). 5 refs, 3 figs, 2 tabs

  12. Real-time electronic monitoring of a pitted and leaking gas gathering pipeline

    Energy Technology Data Exchange (ETDEWEB)

    Asperger, R.G.; Hewitt, P.G.

    1986-08-01

    Hydrogen patch, flush electrical resistance, and flush linear polarization proves wre used with flush coupons to monitor corrosion rates in a pitted and leaking sour gas gathering line. Four inhibitors were evaluated in stopping the leaks. Inhibitor residuals and the amount and ratio of water and condensate in the lines were measured at five locations along the line. The best inhibitor reduced reduced the pit-leak frequency by over a factor of 10. Inhibitor usage rate was optimized using the hydrogen patch current as a measure of the instantaneous corrosion rate. Improper pigging was identified as a cause of corrosion transients. This problem is discussed in relation to the pigging of pipelines in stratified flow where moving fluids are the carriers for continuously injected corrosion inhibitors.

  13. Easy method enhancing the sensitivity of a helium mass-spectrometer leak detector

    International Nuclear Information System (INIS)

    Firpo, G.; Pozzo, A.

    2004-01-01

    Commercial He mass spectrometer leak detectors usually do not provide sufficient sensitivity to perform accurate measurements of the permeation rate of He through glass. Ultrasensitive dedicated systems have adeguate sensitivity but involve high costs and complex procedures. However, both cryogenics and photomultiplier technology routinely demand this goal. Here, we propose a novel method to increase the sensitivity of commercial devices to easily measure accurate permeation rate. We modified a commercial leak detector by reducing the pumping speed at the inlet of the rotary pump, thus increasing its sensitivity by one order of magnitude. The modified detector was used to measure the leak rate of the permeation of He through the glass walls of a photomultiplier. Further improvements made to decrease the minimum detectable signal were limited by the high ultimate pressure in the spectrometer tube

  14. Calculation of wastage by small water leaks in sodium heated steam generators

    International Nuclear Information System (INIS)

    Tregonning, K.

    1976-01-01

    On the basis of mechanistic arguments it is suggested that the temperature of the wasting surface would provide a single physically meaningful parameter with which to correlate wastage data. A lumped parameter model is developed which predicts reaction temperature as a function of the major variables in the small water leak situation (Leak rate, tube spacing, sodium temperature). The calculated temperatures explain much of the observed behaviour of wastage rate with these variables and compare well with the limited temperature data available. Wastage rates are correlated with predicted temperature on a total activation energy basis. The results are encouraging and a first conservative method for the calculation of wastage by small water leaks in sodium-heated steam generators is produced

  15. CT assessment of anastomotic bowel leak

    International Nuclear Information System (INIS)

    Power, N.; Atri, M.; Ryan, S.; Haddad, R.; Smith, A.

    2007-01-01

    Aim: To evaluate the predictors of clinically important gastrointestinal anastomotic leaks using multidetector computed tomography (CT). Subjects and methods: Ninety-nine patients, 73 with clinical suspicion of anastomotic bowel leak and 26 non-bowel surgery controls underwent CT to investigate postoperative sepsis. Fifty patients had undergone large bowel and 23 small bowel anastomoses. The time interval from surgery was 3-30 days (mean 10 ± 5.9 SD) for the anastomotic group and 3-40 days (mean 14 ± 11 SD) for the control group (p = 0.3). Two radiologists blinded to the final results reviewed the CT examinations in consensus and recorded the presence of peri-anastomotic air, fluid or combination of the two; distant loculated fluid or combination of fluid and air; free air or fluid; and intestinal contrast leak. Final diagnosis of clinically important anastomotic leak (CIAL) was confirmed at surgery or by chart review of predetermined clinical and laboratory criteria. Results: The prevalence of CIAL in the group undergoing CT was 31.5% (23/73). The CT examinations with documented leak were performed 5-28 (mean; 11.4 ± 6 SD) days after surgery. Nine patients required repeat operation, 10 percutaneous abscess drainage, two percutaneous drainage followed by surgery, and two prolonged antibiotic treatment and total parenteral nutrition (TPN). Of the CT features examined, only peri-anastomotic loculated fluid containing air was more frequently seen in the CIAL group as opposed to the no leak group (p = 0.04). There was no intestinal contrast leakage in this cohort. Free air was present up to 9 days and loculated air up to 26 days without CIAL. Conclusion: Most postoperative CT features overlap between patients with and without CIAL. The only feature seen statistically more frequently with CIAL is peri-anastomotic loculated fluid containing air

  16. CT assessment of anastomotic bowel leak

    Energy Technology Data Exchange (ETDEWEB)

    Power, N. [Department of Radiology, Sunnybrook Hospital, Toronto, Ontario M4N 3M5 (Canada); Atri, M. [Department of Radiology, Sunnybrook Hospital, Toronto, Ontario M4N 3M5 (Canada)]. E-mail: mostafa.atri@sw.ca; Ryan, S. [Department of Radiology, Sunnybrook Hospital, Toronto, Ontario M4N 3M5 (Canada); Haddad, R. [Department of Surgery, Sunnybrook Hospital, Toronto, Ontario M4N 3M5 (Canada); Smith, A. [Department of Surgery, Sunnybrook Hospital, Toronto, Ontario M4N 3M5 (Canada)

    2007-01-15

    Aim: To evaluate the predictors of clinically important gastrointestinal anastomotic leaks using multidetector computed tomography (CT). Subjects and methods: Ninety-nine patients, 73 with clinical suspicion of anastomotic bowel leak and 26 non-bowel surgery controls underwent CT to investigate postoperative sepsis. Fifty patients had undergone large bowel and 23 small bowel anastomoses. The time interval from surgery was 3-30 days (mean 10 {+-} 5.9 SD) for the anastomotic group and 3-40 days (mean 14 {+-} 11 SD) for the control group (p = 0.3). Two radiologists blinded to the final results reviewed the CT examinations in consensus and recorded the presence of peri-anastomotic air, fluid or combination of the two; distant loculated fluid or combination of fluid and air; free air or fluid; and intestinal contrast leak. Final diagnosis of clinically important anastomotic leak (CIAL) was confirmed at surgery or by chart review of predetermined clinical and laboratory criteria. Results: The prevalence of CIAL in the group undergoing CT was 31.5% (23/73). The CT examinations with documented leak were performed 5-28 (mean; 11.4 {+-} 6 SD) days after surgery. Nine patients required repeat operation, 10 percutaneous abscess drainage, two percutaneous drainage followed by surgery, and two prolonged antibiotic treatment and total parenteral nutrition (TPN). Of the CT features examined, only peri-anastomotic loculated fluid containing air was more frequently seen in the CIAL group as opposed to the no leak group (p = 0.04). There was no intestinal contrast leakage in this cohort. Free air was present up to 9 days and loculated air up to 26 days without CIAL. Conclusion: Most postoperative CT features overlap between patients with and without CIAL. The only feature seen statistically more frequently with CIAL is peri-anastomotic loculated fluid containing air.

  17. LMFBR steam generator leak detection development in the United States

    Energy Technology Data Exchange (ETDEWEB)

    Magee, P M; Gerrels, E E; Greene, D A [General Electric Company, Sunnyvale, CA (United States); McKee, J [Argonne National Laboratory, Argonne, IL (United States)

    1978-10-01

    Leak detection for Liquid Metal Fast Breeder Reactor steam generators is an important economic factor in the shutdown, repair and restart of a plant. Development of leak detection systems in the U.S. has concentrated on four areas: (1) chemical (H{sub 2} and O{sub 2}) leak detection meters; (2) acoustic leak detection/location techniques; (3) investigation of leak behavior (enlargement, damage effects, plugging and unplugging); and (4) data management for plant operations. This paper discusses the status, design aspects, and applications of leak detection technology for LMFBR plants. (author)

  18. LMFBR steam generator leak detection development in the United States

    International Nuclear Information System (INIS)

    Magee, P.M.; Gerrels, E.E.; Greene, D.A.; McKee, J.

    1978-01-01

    Leak detection for Liquid Metal Fast Breeder Reactor steam generators is an important economic factor in the shutdown, repair and restart of a plant. Development of leak detection systems in the U.S. has concentrated on four areas: (1) chemical (H 2 and O 2 ) leak detection meters; (2) acoustic leak detection/location techniques; (3) investigation of leak behavior (enlargement, damage effects, plugging and unplugging); and (4) data management for plant operations. This paper discusses the status, design aspects, and applications of leak detection technology for LMFBR plants. (author)

  19. Fuel leak detection on large transport airplanes

    OpenAIRE

    Behbahani-Pour, M.J.; Radice, G.

    2016-01-01

    Fuel leakage has the risk of being ignited by external ignition sources, and therefore it is important to detect\\ud any fuel leakage before the departure of the aircraft. Currently, there are no fuel leak detection systems installed\\ud on commercial aircrafts, to detect fuel tank leakage, while only a small number of more recent aircraft, have a fuel\\ud monitoring system, that generates a fuel leak-warning message in cockpit in the case of fuel imbalance between the\\ud tanks. The approach pro...

  20. Technique for detecting liquid metal leaks

    International Nuclear Information System (INIS)

    Bauerle, J.E.

    1979-01-01

    In a system employing flowing liquid metal as a heat transfer medium in contact with tubular members containing a working fluid, i.e., steam, liquid metal leaks through the wall of the tubular member are detected by dislodging the liquid metal compounds forming in the tubular member at the leak locations and subsequently transporting the dislodged compound in the form of an aerosol to a detector responsive to the liquid metal compound. In the application to a sodium cooled tubular member, the detector would consist of a sodium responsive device, such as a sodium ion detector

  1. Hydrogen detection systems leak response codes

    International Nuclear Information System (INIS)

    Desmas, T.; Kong, N.; Maupre, J.P.; Schindler, P.; Blanc, D.

    1990-01-01

    A loss in tightness of a water tube inside a Steam Generator Unit of a Fast Reactor is usually monitored by hydrogen detection systems. Such systems have demonstrated in the past their ability to detect a leak in a SGU. However, the increase in size of the SGU or the choice of ferritic material entails improvement of these systems in order to avoid secondary leak or to limit damages to the tube bundle. The R and D undertaken in France on this subject is presented. (author). 11 refs, 10 figs

  2. Acoustic leak detection development in the USA

    International Nuclear Information System (INIS)

    Greene, D.A.; Malovrh, J.W.; Magee, P.M.

    1984-01-01

    Acoustic monitoring systems that detect and locate a leak of water/steam from a defective tube in an LMFBR steam generator have been developed in the United States. A low frequency (approx. 10 KHz) system was developed by General Electric, and a high frequency (200 to 300 KHz) system by Rockwell International with support from Argonne National Laboratory. A comprehensive base technology program provided absolute signal amplitudes, background noise amplitudes, and signal source-to-detector transfer functions. Field tests of these systems demonstrated an ability to detect and locate simulated leaks under operating and quiescent conditions in an LMFBR steam generator. (author)

  3. Transanal Drainage of Coloanal Anastomotic Leaks

    Directory of Open Access Journals (Sweden)

    Bradley Sherman

    2018-01-01

    Full Text Available The conventional operative intervention for leaks following coloanal anastomoses has been proximal fecal diversion with or without take-down of anastomosis. A few of these cases are also amenable to percutaneous drainage. Ostomies created in this situation are often permanent, specifically in cases where coloanal anastomoses are taken down at the time of reoperation. We present two patients who developed perianastomotic pelvic abscesses that were treated with transanal large bore catheter drainage resulting in successful salvage of coloanal anastomoses without the need for a laparotomy or ostomy creation. We propose this to be an effective therapeutic approach to leaks involving low coloanal anastomoses in the absence of generalized peritonitis.

  4. Apparatus for Leak Testing Pressurized Hoses

    Science.gov (United States)

    Underwood, Steve D. (Inventor); Garrison, Steve G. (Inventor); Gant, Bobby D. (Inventor); Palmer, John R. (Inventor)

    2015-01-01

    A hose-attaching apparatus for leak-testing a pressurized hose may include a hose-attaching member. A bore may extend through the hose-attaching member. An internal annular cavity may extend coaxially around the bore. At least one of a detector probe hole and a detector probe may be connected to the internal annular cavity. At least a portion of the bore may have a diameter which is at least one of substantially equal to and less than a diameter of a hose to be leak-tested.

  5. Anatomy of a defective barrier: sequential glove leak detection in a surgical and dental environment.

    Science.gov (United States)

    Albin, M S; Bunegin, L; Duke, E S; Ritter, R R; Page, C P

    1992-02-01

    a) To determine the frequency of perforations in latex surgical gloves before, during, and after surgical and dental procedures; b) to evaluate the topographical distribution of perforations in latex surgical gloves after surgical and dental procedures; and c) to validate methods of testing for latex surgical glove patency. Multitrial tests under in vitro conditions and a prospective sequential patient study using consecutive testing. An outpatient dental clinic at a university dental school, the operating suite in a medical school affiliated with the Veteran's Hospital, and a biomechanics laboratory. Surgeons, scrub nurses, and dental technicians participating in 50 surgical and 50 dental procedures. We collected 679 latex surgical gloves after surgical procedures and tested them for patency by using a water pressure test. We also employed an electronic glove leak detector before donning, after sequential time intervals, and upon termination of 47 surgical (sequential surgical), 50 dental (sequential dental), and in three orthopedic cases where double gloving was used. The electronic glove leak detector was validated by using electronic point-by-point surface probing, fluorescein dye diffusion, as well as detecting glove punctures made with a 27-gauge needle. The random study indicated a leak rate of 33.0% (224 out of 679) in latex surgical gloves; the sequential surgical study demonstrated patency in 203 out of 347 gloves (58.5%); the sequential dental study showed 34 leaks in the 106 gloves used (32.1%); and with double gloving, the leak rate decreased to 25.0% (13 of 52 gloves tested). While the allowable FDA defect rate for unused latex surgical gloves is 1.5%, we noted defect rates in unused gloves of 5.5% in the sequential surgical, 1.9% in the sequential dental, and 4.0% in our electronic glove leak detector validating study. In the sequential surgical study, 52% of the leaks had occurred by 75 mins, and in the sequential dental study, 75% of the leaks

  6. Review of nuclear power reactor coolant system leakage events and leak detection requirements

    International Nuclear Information System (INIS)

    Chokshi, N.C.; Srinivasan, M.; Kupperman, D.S.; Krishnaswamy, P.

    2005-01-01

    In response to the vessel head event at the Davis-Besse reactor, the U.S. Nuclear Regulatory Commission (NRC) formed a Lessons Learned Task Force (LLTF). Four action plans were formulated to respond to the recommendations of the LLTF. The action plans involved efforts on barrier integrity, stress corrosion cracking (SCC), operating experience, and inspection and program management. One part of the action plan on barrier integrity was an assessment to identify potential safety benefits from changes in requirements pertaining to leakage in the reactor coolant system (RCS). In this effort, experiments and models were reviewed to identify correlations between crack size, crack-tip-opening displacement (CTOD), and leak rate in the RCS. Sensitivity studies using the Seepage Quantification of Upsets In Reactor Tubes (SQUIRT) code were carried out to correlate crack parameters, such as crack size, with leak rate for various types of crack configurations in RCS components. A database that identifies the leakage source, leakage rate, and resulting actions from RCS leaks discovered in U.S. light water reactors was developed. Humidity monitoring systems for detecting leakage and acoustic emission crack monitoring systems for the detection of crack initiation and growth before a leak occurs were also considered. New approaches to the detection of a leak in the reactor head region by monitoring boric-acid aerosols were also considered. (authors)

  7. Complications of Minimally Invasive, Tubular Access Surgery for Cervical, Thoracic, and Lumbar Surgery

    Directory of Open Access Journals (Sweden)

    Donald A. Ross

    2014-01-01

    Full Text Available The object of the study was to review the author’s large series of minimally invasive spine surgeries for complication rates. The author reviewed a personal operative database for minimally access spine surgeries done through nonexpandable tubular retractors for extradural, nonfusion procedures. Consecutive cases (n=1231 were reviewed for complications. There were no wound infections. Durotomy occurred in 33 cases (2.7% overall or 3.4% of lumbar cases. There were no external or symptomatic internal cerebrospinal fluid leaks or pseudomeningoceles requiring additional treatment. The only motor injuries were 3 C5 root palsies, 2 of which resolved. Minimally invasive spine surgery performed through tubular retractors can result in a low wound infection rate when compared to open surgery. Durotomy is no more common than open procedures and does not often result in the need for secondary procedures. New neurologic deficits are uncommon, with most observed at the C5 root. Minimally invasive spine surgery, even without benefits such as less pain or shorter hospital stays, can result in considerably lower complication rates than open surgery.

  8. The effects of air leaks on solar air heating systems

    Science.gov (United States)

    Elkin, R.; Cash, M.

    1979-01-01

    This paper presents the results of an investigation to determine the effects of leakages in collector and duct work on the system performance of a typical single-family residence solar air heating system. Positive (leakage out) and negative (leakage in) pressure systems were examined. Collector and duct leakage rates were varied from 10 to 30 percent of the system flow rate. Within the range of leakage rates investigated, solar contribution to heated space and domestic hot water loads was found to be reduced up to 30 percent from the no-leak system contribution with duct leakage equally divided between supply and return duct; with supply duct leakage greater than return leakage a reduction of up to 35 percent was noted. The negative pressure system exhibited a reduction in solar contribution somewhat larger than the positive pressure system for the same leakage rates.

  9. Localized leak detection utilizing moisture sensitive tape

    International Nuclear Information System (INIS)

    Riddle, P.

    1984-01-01

    Moisture sensitive tape (MST) has been used in various nuclear power plants to detect leaks in reactor piping systems. The sensor assembly consists of MST, transponder, and sensor carrier, and is installed on the exterior of thermal insulation. The components, applications, installation, and purchasing information are discussed in the paper

  10. Steam generator leak detection using acoustic method

    International Nuclear Information System (INIS)

    Goluchko, V.V.; Sokolov, B.M.; Bulanov, A.N.

    1982-05-01

    The main requirements to meet by a device for leak detection in sodium - water steam generators are determined. The potentialities of instrumentation designed based on the developed requirements have been tested using a model of a 550 kw steam generator [fr

  11. GASFLOW analysis of a tritium leak accident

    International Nuclear Information System (INIS)

    Farman, R.F.; Fujita, R.K.; Travis, J.R.

    1994-01-01

    The consequences of an earthquake-induced fire involving a tritium leak were analyzed using the GASFLOW computer code. Modeling features required by the analysis include ventilation boundary conditions, flow of a gas mixture in an enclosure containing obstacles, thermally induced buoyancy, and combustion phenomena. (author). 2 refs., 6 figs

  12. GASFLOW analysis of a tritium leak accident

    International Nuclear Information System (INIS)

    Farman, R.F.; Fujita, R.K.; Travis, J.R.

    1994-01-01

    The consequences of an earthquake-induced fire involving a tritium leak were analyzed using the GASFLOW computer code. Modeling features required by the analysis include ventilation boundary conditions, flow of a gas mixture in an enclosure containing obstacles, thermally induced buoyancy, and combustion phenomena

  13. Detecting gas leaks by ultrasonic emission

    DEFF Research Database (Denmark)

    Rasmussen, Karsten Bo; Henriksen, Eigil

    1997-01-01

    The emission of noise in the frequency range 10 kHz to 25.6 kHz from an experimental gas leak in a flanged joint has been experimentally investigated. The overall conclusion is that the emitted noise is almost frequency independent in level within the considered frequency range.A small PC program...

  14. A Quick Guide to Paravalvular Leak Closure

    Science.gov (United States)

    Gafoor, Sameer; Franke, Jennifer; Bertog, Stefan; Lam, Simon; Vaskelyte, Laura; Hofmann, Ilona; Matic, Predrag

    2015-01-01

    Paravalvular leak (PVL) is a seldomly covered aspect of structural heart disease. However, this is a condition that frequently presents after valvular replacement. This article will cover the diagnosising and treating PVL (i.e. imaging, access, and device selection). In addition, specific aspects of aortic and mitral PVL closure will be covered in this review. PMID:29588686

  15. The concept of leak before failure

    International Nuclear Information System (INIS)

    Pellissier-Tanon, A.

    1985-01-01

    The ability to demonstrate the state of leak before failure introduce a new tangible element in the estimation of safety from which it becomes possible to estimate more rationnally the risks associated to crack formation. This paper presents the international positions on the full section break suppression of steam and primary pipes (Federal Republic of Germany, USA, France) [fr

  16. Development of pressure boundaries leak detection technology for nuclear reactor

    International Nuclear Information System (INIS)

    Zhang Yao; Zhang Dafa; Chen Dengke; Zhang Liming

    2008-01-01

    The leak detection for the pressure boundaries is an important safeguard in nuclear reactor operation. In the paper, the status and the characters on the development of the pressure boundaries leak detection technology for the nuclear reactor were reviewed, especially, and the advance of the radiation leak detection technology and the acoustic emission leak detection technology were analyzed. The new advance trend of the leak detection technology was primarily explored. According to the analysis results, it is point out that the advancing target of the leak detection technology is to enhance its response speed, sensitivity, and reliability, and to provide effective information for operator and decision-maker. The realization of the global leak detection and the whole life cycle health monitoring for the nuclear boundaries is a significant advancing tendency of the leak detection technology. (authors)

  17. Migration of methane into groundwater from leaking production wells near Lloydminster

    International Nuclear Information System (INIS)

    1995-03-01

    The problem of migration of methane from leaking oil and gas wells into aquifers in the Lloydminster area in Saskatchewan, was discussed. A study was conducted to determine if the methane in shallow aquifers near the leaking wells, came from the wells or occurred naturally. Migration rate in aquifers, concentration gradients and approximate flux rates of methane from leaking wells to shallow aquifers, were studied. The methods of investigation included drilling of test holes at selected sites, installation of monitoring wells, purging of wells, pumping tests and water level monitoring, sampling and analyses for dissolved methane. The relatively high methane concentrations in many of the monitoring wells indicated the presence of a methane plume that has migrated from the production well. It was suggested that other leaky well sites in the area should be investigated to determine if similar plumes were present. 18 refs., 5 tabs., 13 figs

  18. Primary flow meter for calibrating a sniffer test leak artefact by a pressure rise method

    Science.gov (United States)

    Arai, Kenta; Yoshida, Hajime

    2014-10-01

    Sniffer tests are used to locate leaks in equipment during operation. The sensitivity of a sniffer leak detector must be calibrated against a known gas flow to atmospheric pressure generated by a sniffer test leak artefact. We have developed a primary flow meter for calibrating gas flows to atmospheric pressure through the leak artefact. The flow meter is based on a pressure rise method and two chambers are used to measure the pressure rise with small uncertainty even at atmospheric pressure. The calibration range of the flow rate is 5 × 10-7 Pa m3 s-1 to 7 × 10-4 Pa m3 s-1 to atmospheric pressure at 23.0 °C with a minimum uncertainty of 1.4% (k = 2), as well as 4 × 10-8 Pa m3 s-1 to 5 × 10-4 Pa m3 s-1 to a vacuum at 23.0 °C. The long term stability of the flow meter was determined as 0.41% by repeated measurements of the conductance of the leak artefact. In case of the flow rate into a vacuum, the flow meter was successfully linked to the international reference value of CCM.P-K12 by a lab-internal comparison.

  19. Water Pipeline Monitoring and Leak Detection using Flow Liquid Meter Sensor

    Science.gov (United States)

    Rahmat, R. F.; Satria, I. S.; Siregar, B.; Budiarto, R.

    2017-04-01

    Water distribution is generally installed through underground pipes. Monitoring the underground water pipelines is more difficult than monitoring the water pipelines located on the ground in open space. This situation will cause a permanent loss if there is a disturbance in the pipeline such as leakage. Leaks in pipes can be caused by several factors, such as the pipe’s age, improper installation, and natural disasters. Therefore, a solution is required to detect and to determine the location of the damage when there is a leak. The detection of the leak location will use fluid mechanics and kinematics physics based on harness water flow rate data obtained using flow liquid meter sensor and Arduino UNO as a microcontroller. The results show that the proposed method is able to work stably to determine the location of the leak which has a maximum distance of 2 metres, and it’s able to determine the leak location as close as possible with flow rate about 10 litters per minute.

  20. Ultrasensitive leak detection during ultrahigh vacuum evacuation by quadrupole mass spectrometer

    International Nuclear Information System (INIS)

    Chen Xu; Huang Tianbin; Wang Ligong; Jin Qiji; Cha Liangzhen

    2006-01-01

    One must do ultrasensitive leak detection during ultrahigh-vacuum (UHV) evacuation, especially just before the device is sealed off from the vacuum system, to guarantee the longevity of the sealed high-vacuum or even UHV devices with small volume. A quadrupole mass spectrometer (QMS) with an UHV evacuation system can be used under accumulation mode to do the testing. Possible accumulate modes, as well as their advantages and shortcomings, are studied experimentally and discussed in this paper. We found that the opening action of the metal valve during accumulation mode always severely affects the height of the peak indicated by QMS and causes considerable errors. If we determine the leak rate by the peak area instead of the peak height, the situation is much improved. This method has proven quite useful in ensuring the tightness quality for complex sealed UHV devices with small volumes. Ultrasensitive leak detection has been carried out for such real evacuating devices, and a leak rate of 2x10 -14 Pa·m 3 /s was detected, which is far lower than its dynamic mode and the detection limit of the current advanced commercial leak detectors

  1. Estimation of flow rates through intergranular stress corrosion cracks

    International Nuclear Information System (INIS)

    Collier, R.P.; Norris, D.M.

    1984-01-01

    Experimental studies of critical two-phase water flow, through simulated and actual intergranular stress corrosion cracks, were performed to obtain data to evaluate a leak flow rate model and investigate acoustic transducer effectiveness in detecting and sizing leaks. The experimental program included a parametric study of the effects of crack geometry, fluid stagnation pressure and temperature, and crack surface roughness on leak flow rate. In addition, leak detection, location, and leak size estimation capabilities of several different acoustic transducers were evaluated as functions of leak rate and transducer position. This paper presents flow rate data for several different cracks and fluid conditions. It also presents the minimum flow rate detected with the acoustic sensors and a relationship between acoustic signal strength and leak flow rate

  2. Endoscopic management of biliary injuries and leaks

    Directory of Open Access Journals (Sweden)

    T S Chandrasekar

    2012-01-01

    Full Text Available Bile duct injuries and subsequent leaks can occur following laparoscopic and open cholecystectomies and also during other hepatobiliary surgeries. Various patient related and technical factors are implicated in the causation of biliary injuries. Over a period of twenty five years managing such patients of biliary injuries our team has found a practical approach to assess the cause of biliary injuries based on the symptoms, clinical examination and imaging. Bismuth classification is helpful in most of the cases. Immediate referral to a centre experienced in the management of bile duct injury and timely intervention is associated with improved outcomes. Resuscitation, correcting dyselectrolytemia, aspiration of undrained biloma and antibiotics take the priority in the management. The goal is to restore the bile conduit, and to prevent short and longterm complications such as biliary fistula, intra-abdominal abscess, biliary stricture, recurrent cholangitis and secondary biliary cirrhosis. Endoscopic therapy by reducing the transpapillary pressure gradient helps in reducing the leak. Endoscopic therapy with biliary sphincterotomy alone or with additional placement of a biliary stent/ nasobiliary drainage is advocated. In our tertiary care referral unit, we found endoscopic interventions are useful in situations where there is leak with associated CBD calculus or a foreign body, peripheral bile duct injury, cystic duct stump leak and partial bile duct injury with leak/ narrowing of the lumen. Endotherapy is not useful in case of complete transection (total cut off and complete stricture involving common hepatic or common bile ducts. In conclusion, endoscopic treatment can be considered a highly effective therapy and should be the first-line therapy in such patients. Though less successful, an endoscopic attempt is warranted in patients suffering from central bile duct leakages failing which surgical management is recommended.

  3. Modeling leaks from liquid hydrogen storage systems.

    Energy Technology Data Exchange (ETDEWEB)

    Winters, William Stanley, Jr.

    2009-01-01

    This report documents a series of models for describing intended and unintended discharges from liquid hydrogen storage systems. Typically these systems store hydrogen in the saturated state at approximately five to ten atmospheres. Some of models discussed here are equilibrium-based models that make use of the NIST thermodynamic models to specify the states of multiphase hydrogen and air-hydrogen mixtures. Two types of discharges are considered: slow leaks where hydrogen enters the ambient at atmospheric pressure and fast leaks where the hydrogen flow is usually choked and expands into the ambient through an underexpanded jet. In order to avoid the complexities of supersonic flow, a single Mach disk model is proposed for fast leaks that are choked. The velocity and state of hydrogen downstream of the Mach disk leads to a more tractable subsonic boundary condition. However, the hydrogen temperature exiting all leaks (fast or slow, from saturated liquid or saturated vapor) is approximately 20.4 K. At these temperatures, any entrained air would likely condense or even freeze leading to an air-hydrogen mixture that cannot be characterized by the REFPROP subroutines. For this reason a plug flow entrainment model is proposed to treat a short zone of initial entrainment and heating. The model predicts the quantity of entrained air required to bring the air-hydrogen mixture to a temperature of approximately 65 K at one atmosphere. At this temperature the mixture can be treated as a mixture of ideal gases and is much more amenable to modeling with Gaussian entrainment models and CFD codes. A Gaussian entrainment model is formulated to predict the trajectory and properties of a cold hydrogen jet leaking into ambient air. The model shows that similarity between two jets depends on the densimetric Froude number, density ratio and initial hydrogen concentration.

  4. Investigation for the sodium leak in Monju. Sodium leak and fire test-1

    International Nuclear Information System (INIS)

    Kawata, Koji; Ohno, Shuji; Miyahara, Shinya; Miyake, Osamu; Tanabe, Hiromi

    2000-08-01

    As a part of the work for investigating the sodium leak accident which occurred in the Monju reactor (hereinafter referred to as Monju) on December 8, 1995, three tests, (1) a sodium leak test, (2) a sodium leak and fire test-1, and (3) a sodium leak and fire test-II, were carried out at OEC/PEC. The main objectives of these tests were to confirm the leak and burning behavior of sodium from the damaged thermometer, and the effects of the sodium fire on the integrity of the surrounding structure. This report describes the results of the sodium fire test-I carried out as a preliminary test. The test was performed using the SOLFA-2 (Sodium Leak, Fire and Aerosol) facility on April 8, 1996. In this test, sodium heated to 480degC was leaked for approximately 1.5 hours from a leak simulating apparatus and caused to drop onto a ventilation duct and a grating with the same dimensions and layout as those in Monju. The main conclusions obtained from the test are shown below: 1) Observation from video cameras in the test revealed that in the early stages of the sodium leak, sodium dripped out of the flexible tube of the thermometer. This dripping and burning expanded in range as the sodium splashed on the duct. 2) No damage to the duct itself was detected. However, the aluminum louver frame of the ventilation duct's lower inlet was damaged. Its machine screws came off, leaving half of the grill (on the grating side) detached. 3) No large hole, like the one seen at Monju, was found when the grating was removed from the testing system for inspection, although the area centered on the point were the sodium dripped was damaged in a way indicating the first stages of grating failure. The 5mm square lattice was corroded through in some parts, and numerous blades (originally 3.2 mm thick) had become sharpened like the blade of a knife. 4) The burning pan underside thermocouple near the leak point measured 700degC in within approximately 10 minutes, and for the next hour remained

  5. Dynamic pressure measures for long pipeline leak detection

    Energy Technology Data Exchange (ETDEWEB)

    Likun Wang; Hongchao Wang; Min Xiong; Bin Xu; Dongjie Tan; Hengzhang Zhou [PetroChina Pipeline Company, Langfang (China). R and D Center

    2009-07-01

    Pipeline leak detection method based on dynamic pressure is studied. The feature of dynamic pressure which is generated by the leakage of pipeline is analyzed. The dynamic pressure method is compared with the static pressure method for the advantages and disadvantages in pipeline leak detection. The dynamic pressure signal is suitable for pipeline leak detection for quick-change of pipeline internal pressure. Field tests show that the dynamic pressure method detects pipeline leak rapidly and precisely. (author)

  6. Endoscopic transnasal repair of cerebrospinal fluid leaks with and without an encephalocele in pediatric patients: from infants to children.

    Science.gov (United States)

    Ma, Jingying; Huang, Qian; Li, Xiaokui; Huang, Dongsheng; Xian, Junfang; Cui, Shunjiu; Li, Yunchuan; Zhou, Bing

    2015-09-01

    The diagnosis and management of pediatric cerebrospinal fluid (CSF) leak and encephalocele are challenging. The current study aimed to identify patient characteristics, review operative techniques, and evaluate the efficacy and safety of endoscopic endonasal repair in a pediatric population. We retrospectively reviewed the records of pediatric patients who underwent transnasal endoscopic repair of CSF leak with or without a meningocele or an encephalocele at Beijing Tongren Hospital, Capital Medical University, between July 2003 and May 2014. All patients had preoperative radiological evaluations and underwent endoscopic endonasal repair of their skull base defects. Altogether, 23 children (mean age 7.0 years) underwent the procedures. Sixteen cases were congenital, and 7 patients had trauma history. The herniations or defects included meningoencephaloceles in 15 cases, meningoceles in 4 cases, and CSF leak in 4 cases (2 patients had bilateral leaks). The leak or herniation sites were ethmoid roof in 10 patients (one was bilateral), cribriform plate in 5, lateral to the foramen cecum in 3, posterior wall of the frontal sinus in 1, sphenoid sinus in 2, lateral recess of the sphenoid sinus in 1, and sella turcica base in 2. All subjects had favorable clinical outcomes without recurrence during a follow-up of 6-123 months (mean 61.1 months). The endoscopic endonasal approach was the preferred method for repairing CSF leaks with or without an encephalocele in pediatric patients. Compared to traditional operations, this endoscopic procedure is minimally invasive, efficient, and safe.

  7. 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

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

    International Nuclear Information System (INIS)

    Shimoyama, Kazuhito

    2004-03-01

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

  9. Acoustic leak detection at complicated topologies using neural netwoks

    International Nuclear Information System (INIS)

    Hessel, G.; Schmitt, W.; Weiss, F.P.

    1994-01-01

    Considering the shortcomings of all the existing leak detecting principles, a new method again based on the measurement of the leak induced sound but also applying pattern recognition is being developed. The capability of neural networks to localize leaks at the reactor pressure vessel (RPV) head of VVER-440 reactors is discussed. (orig./DG)

  10. Damage phenomena at target surface by small leak

    International Nuclear Information System (INIS)

    Jeong, Kyung Chai; Jeong, J. Y.; Kim, B. H.; Kim, T. J.; Choi, J. H.

    2001-04-01

    Design of the steam generator should be considered the safety about the sodium-water reaction occurred by water leak in heat transfer tube. Water leak mainly occurred from welding defect at the process of tube connection, the vibration of heat transfer tube bundle in steam generating system, fretting, and pin hole in original tube manufacturing. The classification of water leak divided to two parts, roughly, in case of the water leak studies. One is small leak phenomena analysis, and the other is it of large leak which was mainly treated to the evaluation on pressure increasing from hydrogen gas formed by sodium-water reaction in sodium system. In small water leak, the leak propagation phenomena and the development of leak detecting system at initial stage of small water leak were studied, mainly. In this study, the corrosion phenomena on the target tube surface appeared by sodium-water reaction was analyzed through the small water leak experiments, and, also, the jet phenomena formed by N 2 gas injection through the leak nozzle under water medium was observed

  11. Small leak detection requirements for SNR-300 steam generator operation

    International Nuclear Information System (INIS)

    Dumm, K.

    1975-01-01

    The leak detection philosophy of the SNR-300 steam generators is described. Due to operational demands small leaks have already to be detectable at a stage where secondary tube damage has not yet occurred. The requirements on a leak detection instrument are developed and the instrument itself is described. (author)

  12. Double Shell Tank AY-102 Radioactive Waste Leak Investigation

    International Nuclear Information System (INIS)

    Washenfelder, Dennis J.

    2014-01-01

    PowerPoint. The objectives of this presentation are to: Describe Effort to Determine Whether Tank AY-102 Leaked; Review Probable Causes of the Tank AY-102 Leak; and, Discuss Influence of Leak on Hanford's Double-Shell Tank Integrity Program

  13. 1999 Leak Detection, Monitoring, and Mitigation Strategy Update

    International Nuclear Information System (INIS)

    OHL, P.C.

    1999-01-01

    This document is a complete revision of WHC-SD-WM-ES-378, Rev 1. This update includes recent developments in Leak Detection, Leak Monitoring, and Leak Mitigation technologies, as well as, recent developments in single-shell tank retrieval technologies. In addition, a single-shell tank retrieval release protection strategy is presented

  14. Special storage of leaking fuel at Paks NPP

    International Nuclear Information System (INIS)

    Biro, Janos; Szőke, L.; Burján, T.; Lukács, R.; Hózer, H.

    2015-01-01

    In this paper the activities related with spent, hermetic as well as leaking fuel handling and storage, including: Spent fuel pool; Transportation criteria for the spent fuel assemblies and Interim spent fuel dry storage; Short-term storage in the spent fuel pool; Identification of the leaking assemblies by the TS-device; Present conception of Identification, handling of the leaking FAs; Modified transport procedure for the leaking FAs; Calculation of solved activity inside the leaking fuel rod; Solved activity limit values for the leaking FAs; Long-term storage in the interim spent Fuel dry storage are presented. At the end authors’ concluded that: 1) The leaking FA can be transported to the interim dry storage together with the other spent fuel assemblies in the transport container. 2) The transport-documentation of the leaking FA has to contain: isotope inventory, calculated solved activity values of the failed FA and the quantity of failed fuel rods. 3) Performing three leakage tests of the identified leaking FA before the transportation in the 5FP. it is useful to decrease the solved activity concentration inside the leaking FA and give additional information about the extent of the leakage. 4) We can calculate simply the solved activity of the leaking FA. 5) The modified transport procedure will have to be authorized. 6) The radiological effects of the leaking FA are negligible relative to the natural background radiation

  15. Final evaluation of advanced and current leak detection systems

    International Nuclear Information System (INIS)

    Kupperman, D.S.; Carlson, R.; Brewer, W.; Lanham, R.

    1989-01-01

    This report presents the results of a study to evaluate the adequacy of leak detection systems in light water reactors. The sources of numerous reported leaks and methods of detection have been documented. Research to advance the state of the art of acoustic leak detection is presented, and procedures for implementation are discussed

  16. Automated leak localization performance without detailed demand distribution data

    NARCIS (Netherlands)

    Moors, Janneke; Scholten, L.; van der Hoek, J.P.; den Besten, J.

    2018-01-01

    Automatic leak localization has been suggested to reduce the time and personnel efforts needed to localize
    (small) leaks. Yet, the available methods require a detailed demand distribution model for successful
    calibration and good leak localization performance. The main aim of this work was

  17. Water leaks in sodium-heated fast reactor boilers

    International Nuclear Information System (INIS)

    Hayes, D.J.

    1978-01-01

    Constraints on plant design which may result from considerations of leak behaviour and leak detection limits are briefly considered. The sodium-water interface and reactions, the behaviour of small leaks, hydrogen bubbles and detection methods, including galvanic cell methods, are included. (UK)

  18. 40 CFR 63.648 - Equipment leak standards.

    Science.gov (United States)

    2010-07-01

    ... 40 Protection of Environment 10 2010-07-01 2010-07-01 false Equipment leak standards. 63.648...) National Emission Standards for Hazardous Air Pollutants From Petroleum Refineries § 63.648 Equipment leak...) through (c)(10) and (e) through (i) of this section. (1) The instrument readings that define a leak for...

  19. 40 CFR 63.769 - Equipment leak standards.

    Science.gov (United States)

    2010-07-01

    ... 40 Protection of Environment 10 2010-07-01 2010-07-01 false Equipment leak standards. 63.769... § 63.769 Equipment leak standards. (a) This section applies to equipment subject to this subpart and... release to detect leaks, except under the following conditions. (i) The owner or operator has obtained...

  20. 40 CFR 63.1331 - Equipment leak provisions.

    Science.gov (United States)

    2010-07-01

    ... 40 Protection of Environment 11 2010-07-01 2010-07-01 true Equipment leak provisions. 63.1331... Standards for Hazardous Air Pollutant Emissions: Group IV Polymers and Resins § 63.1331 Equipment leak... in pumps and agitator seals in light liquid service shall not be considered to be a leak. For...

  1. 10 CFR 39.35 - Leak testing of sealed sources.

    Science.gov (United States)

    2010-01-01

    ... 10 Energy 1 2010-01-01 2010-01-01 false Leak testing of sealed sources. 39.35 Section 39.35 Energy....35 Leak testing of sealed sources. (a) Testing and recordkeeping requirements. Each licensee who uses... record of leak test results in units of microcuries and retain the record for inspection by the...

  2. 40 CFR 63.1434 - Equipment leak provisions.

    Science.gov (United States)

    2010-07-01

    ... 40 Protection of Environment 11 2010-07-01 2010-07-01 true Equipment leak provisions. 63.1434... Standards for Hazardous Air Pollutant Emissions for Polyether Polyols Production § 63.1434 Equipment leak provisions. (a) The owner or operator of each affected source shall comply with the HON equipment leak...

  3. 40 CFR 63.1410 - Equipment leak provisions.

    Science.gov (United States)

    2010-07-01

    ... 40 Protection of Environment 11 2010-07-01 2010-07-01 true Equipment leak provisions. 63.1410... leak provisions. The owner or operator of each affected source shall comply with the requirements of 40 CFR part 63, subpart UU (national emission standards for equipment leaks (control level 2)) for all...

  4. 49 CFR 195.444 - CPM leak detection.

    Science.gov (United States)

    2010-10-01

    ... 49 Transportation 3 2010-10-01 2010-10-01 false CPM leak detection. 195.444 Section 195.444... PIPELINE Operation and Maintenance § 195.444 CPM leak detection. Each computational pipeline monitoring (CPM) leak detection system installed on a hazardous liquid pipeline transporting liquid in single...

  5. 49 CFR 195.134 - CPM leak detection.

    Science.gov (United States)

    2010-10-01

    ... 49 Transportation 3 2010-10-01 2010-10-01 false CPM leak detection. 195.134 Section 195.134... PIPELINE Design Requirements § 195.134 CPM leak detection. This section applies to each hazardous liquid... computational pipeline monitoring (CPM) leak detection system and each replaced component of an existing CPM...

  6. Small leak detection requirements for SNR-300 steam generator operation

    Energy Technology Data Exchange (ETDEWEB)

    Dumm, K

    1975-07-01

    The leak detection philosophy of the SNR-300 steam generators is described. Due to operational demands small leaks have already to be detectable at a stage where secondary tube damage has not yet occurred. The requirements on a leak detection instrument are developed and the instrument itself is described. (author)

  7. The minimally tuned minimal supersymmetric standard model

    International Nuclear Information System (INIS)

    Essig, Rouven; Fortin, Jean-Francois

    2008-01-01

    The regions in the Minimal Supersymmetric Standard Model with the minimal amount of fine-tuning of electroweak symmetry breaking are presented for general messenger scale. No a priori relations among the soft supersymmetry breaking parameters are assumed and fine-tuning is minimized with respect to all the important parameters which affect electroweak symmetry breaking. The superpartner spectra in the minimally tuned region of parameter space are quite distinctive with large stop mixing at the low scale and negative squark soft masses at the high scale. The minimal amount of tuning increases enormously for a Higgs mass beyond roughly 120 GeV

  8. Application of acoustic leak detection technology for the detection and location of leaks in light water reactors

    International Nuclear Information System (INIS)

    Kupperman, D.S.; Prine, D.; Mathieson, T.

    1988-10-01

    This report presents the results of a study to evaluate the adequacy of leak detection systems in light water reactors. The sources of numerous reported leaks and methods of detection have been documented. Research to advance the state of the art of acoustic leak detection is presented, and procedures for implementation are discussed. 14 refs., 70 figs., 10 tabs

  9. An endoscopic mucosal grading system is predictive of leak in stapled rectal anastomoses.

    Science.gov (United States)

    Sujatha-Bhaskar, Sarath; Jafari, Mehraneh D; Hanna, Mark; Koh, Christina Y; Inaba, Colette S; Mills, Steven D; Carmichael, Joseph C; Nguyen, Ninh T; Stamos, Michael J; Pigazzi, Alessio

    2018-04-01

    Anastomotic leak is a devastating postoperative complication following rectal anastomoses associated with significant clinical and oncological implications. As a result, there is a need for novel intraoperative methods that will help predict anastomotic leak. From 2011 to 2014, patient undergoing rectal anastomoses by colorectal surgeons at our institution underwent prospective application of intraoperative flexible endoscopy with mucosal grading. Retrospective review of patient medical records was performed. After creation of the colorectal anastomosis, application of a three-tier endoscopic mucosal grading system occurred. Grade 1 was defined as circumferentially normal appearing peri-anastomotic mucosa. Grade 2 was defined as ischemia or congestion involving 30% of the colon or rectal mucosa or ischemia/congestion involving both sides of the staple line. From 2011 to 2014, a total of 106 patients were reviewed. Grade 1 anastomoses were created in 92 (86.7%) patients and Grade 2 anastomoses were created in 10 (9.4%) patients. All 4 (3.8%) Grade 3 patients underwent immediate intraoperative anastomosis takedown and re-creation, with subsequent re-classification as Grade 1. Demographic and comorbidity data were similar between Grade 1 and Grade 2 patients. Anastomotic leak rate for the entire cohort was 12.2%. Grade 1 patients demonstrated a leak rate of 9.4% (9/96) and Grade 2 patients demonstrated a leak rate of 40% (4/10). Multivariate logistic regression associated Grade 2 classification with an increased risk of anastomotic leak (OR 4.09, 95% CI 1.21-13.63, P = 0.023). Endoscopic mucosal grading is a feasible intraoperative technique that has a role following creation of a rectal anastomosis. Identification of a Grade 2 or Grade 3 anastomosis should provoke strong consideration for immediate intraoperative revision.

  10. Optimal sensor placement for leak location in water distribution networks using genetic algorithms.

    Science.gov (United States)

    Casillas, Myrna V; Puig, Vicenç; Garza-Castañón, Luis E; Rosich, Albert

    2013-11-04

    This paper proposes a new sensor placement approach for leak location in water distribution networks (WDNs). The sensor placement problem is formulated as an integer optimization problem. The optimization criterion consists in minimizing the number of non-isolable leaks according to the isolability criteria introduced. Because of the large size and non-linear integer nature of the resulting optimization problem, genetic algorithms (GAs) are used as the solution approach. The obtained results are compared with a semi-exhaustive search method with higher computational effort, proving that GA allows one to find near-optimal solutions with less computational load. Moreover, three ways of increasing the robustness of the GA-based sensor placement method have been proposed using a time horizon analysis, a distance-based scoring and considering different leaks sizes. A great advantage of the proposed methodology is that it does not depend on the isolation method chosen by the user, as long as it is based on leak sensitivity analysis. Experiments in two networks allow us to evaluate the performance of the proposed approach.

  11. Optimal Sensor Placement for Leak Location in Water Distribution Networks Using Genetic Algorithms

    Directory of Open Access Journals (Sweden)

    Luis E. Garza-Castañón

    2013-11-01

    Full Text Available This paper proposes a new sensor placement approach for leak location in water distribution networks (WDNs. The sensor placement problem is formulated as an integer optimization problem. The optimization criterion consists in minimizing the number of non-isolable leaks according to the isolability criteria introduced. Because of the large size and non-linear integer nature of the resulting optimization problem, genetic algorithms (GAs are used as the solution approach. The obtained results are compared with a semi-exhaustive search method with higher computational effort, proving that GA allows one to find near-optimal solutions with less computational load. Moreover, three ways of increasing the robustness of the GA-based sensor placement method have been proposed using a time horizon analysis, a distance-based scoring and considering different leaks sizes. A great advantage of the proposed methodology is that it does not depend on the isolation method chosen by the user, as long as it is based on leak sensitivity analysis. Experiments in two networks allow us to evaluate the performance of the proposed approach.

  12. Optimal Sensor Placement for Leak Location in Water Distribution Networks Using Genetic Algorithms

    Science.gov (United States)

    Casillas, Myrna V.; Puig, Vicenç; Garza-Castañón, Luis E.; Rosich, Albert

    2013-01-01

    This paper proposes a new sensor placement approach for leak location in water distribution networks (WDNs). The sensor placement problem is formulated as an integer optimization problem. The optimization criterion consists in minimizing the number of non-isolable leaks according to the isolability criteria introduced. Because of the large size and non-linear integer nature of the resulting optimization problem, genetic algorithms (GAs) are used as the solution approach. The obtained results are compared with a semi-exhaustive search method with higher computational effort, proving that GA allows one to find near-optimal solutions with less computational load. Moreover, three ways of increasing the robustness of the GA-based sensor placement method have been proposed using a time horizon analysis, a distance-based scoring and considering different leaks sizes. A great advantage of the proposed methodology is that it does not depend on the isolation method chosen by the user, as long as it is based on leak sensitivity analysis. Experiments in two networks allow us to evaluate the performance of the proposed approach. PMID:24193099

  13. Steam generator leak detection at Bruce A Unit 1

    International Nuclear Information System (INIS)

    Maynard, K.J.; McInnes, D.E.; Singh, V.P.

    1997-01-01

    A new steam generator leak detection system was recently developed and utilized at Bruce A. The equipment is based on standard helium leak detection, with the addition of moisture detection and several other capability improvements. All but 1% of the Unit 1 Boiler 03 tubesheet was inspected, using a sniffer probe which inspected tubes seven at a time and followed by individual tube inspections. The leak search period was completed in approximately 24 hours, following a prerequisite period of several days. No helium leak indications were found anywhere on the boiler. A single water leak indication was found, which was subsequently confirmed as a through-wall defect by eddy current inspection. (author)

  14. Fluid pipeline leak detection and location with miniature RF tags

    Science.gov (United States)

    McIntyre, Timothy J.

    2017-05-16

    Sensors locate troublesome leaks in pipes or conduits that carry a flowing medium. These sensors, through tailored physical and geometric properties, preferentially seek conduit leaks or breaches due to flow streaming. The sensors can be queried via transceivers outside the conduit or located and interrogated inside by submersible unmanned vehicle to identify and characterize the nature of a leak. The sensors can be functionalized with other capabilities for additional leak and pipeline characterization if needed. Sensors can be recovered from a conduit flow stream and reused for future leak detection activities.

  15. 40 CFR 1065.644 - Vacuum-decay leak rate.

    Science.gov (United States)

    2010-07-01

    ... criterion specified in § 1065.345(e). ER06MY08.028 Where: V vac = geometric volume of the vacuum-side of the sampling system. R = molar gas constant. p 2 = Vacuum-side absolute pressure at time t2. T 2 = Vacuum-side...

  16. Process and device for leak rate measurement of an enclosure

    International Nuclear Information System (INIS)

    Giroux, J.

    1989-01-01

    The volume of a cavity, such as a cylinder and a piston, connected to the enclosure (glovebox or reactor containment shell) is varied to find back the previous pressure difference with the outside (positive or negative). Thermometers and a barometer are provided for eventual corrections [fr

  17. Assessment of leak detection capability of Candu 6 annulus gas system using moisture injection tests

    International Nuclear Information System (INIS)

    Nho, Ki Man; Kim, Wang Bae

    1998-01-01

    The Candu 6 reactor assembly consists of an array of 380 pressure tubes, which are installed horizontally in a large cylindrical vessel, the Calandria, containing the low pressure heavy water moderator. The pressure tube is located inside calandria tube and the annulus between these tubes, which forms a closed loop with CO 2 gas recirculating, is called the Annulus Gas System (AGS). It is designed to give an alarm to the operator even for a small pressure tube leak by a very sensitive dew point meter so that he can take a preventive action for the pressure tbe rupture incident. To judge whether the operator action time is enough or not in the design of Wolsung 2, 3, and 4, the Leak Before Break (LBB) assessment is required for the analysis of the pressure tube failure accident. In order to provide the required data for the LBB assessment of Wolsung Units 2, 3, 4, a series of leak detection capability tests was performed by injecting controlled rates of heavy water vapour. The data of increased dew point and rates of rise were measured to determine the alarm set point for dew point rate of rise of Wolsung Unit 2. It was found that the response of the dew point depends on the moisture injection rate, CO 2 gas flow rate and the leak location. The test showed that Candu 6 AGS can detect the very small leaks less than few g/hr and dew point rate of rise alarm can be the most reliable alarm signal to warn the operator. Considering the present results, the first response time of dew point to the AGS CO 2 flow rate is approximated. (author)

  18. Integrated Approaches for the Management of Staple Line Leaks following Sleeve Gastrectomy

    Directory of Open Access Journals (Sweden)

    Mauro Montuori

    2017-01-01

    Full Text Available Introduction. Aim of the study was trying to draw a final flow chart for the management of gastric leaks after laparoscopic sleeve gastrectomy, based on the review of our cases over 10 years’ experience. Material and Methods. We retrospectively reviewed all patients who underwent LSG as a primary operation at the Bariatric Unit of Tor Vergata University Hospital in Rome from 2007 to 2015. Results. Patients included in the study were 418. There were 6 staple line leaks (1.44%. All patients with diagnosis of a leak were initially discharged home in good clinical conditions and then returned to A&E because of the complication. The mean interval between surgery and readmission for leak was 13,4 days (range 6–34 days, SD ± 11.85. We recorded one death (16.67% due to sepsis. The remaining five cases were successfully treated with a mean healing time of the gastric leak of 55,5 days (range 26–83 days; SD ± 25.44. Conclusion. Choosing the proper treatment depends on clinical stability and on the presence or not of collected abscess. Our treatment protocol showed being associated with low complication rate and minor discomfort to the patients, reducing the need for more invasive procedures.

  19. A primary standard for the calibration of sniffer test leak devices

    Science.gov (United States)

    Jousten, Karl; Becker, Ute

    2009-10-01

    Test leaks with a gas flow to atmospheric pressure are often called sniffer test leaks. They are used to calibrate leak detectors for sniffing applications. Sniffer test leaks need calibration against a standard. A primary standard for the calibration of sniffer test leaks with relatively low measurement uncertainties is described. It is assured that the measurement result is traceable to the relevant SI units and that there is a well-known and complete measurement uncertainty budget. The measurement range of the system is from 4 × 10-11 mol s-1 (corresponding to 10-4 Pa l s-1 at 23 °C) to 4 × 10-9 mol s-1 (10-2 Pa l s-1 at 23 °C), which is the most often needed range in industry of around 1 g loss per year of the cooling agent R134a. The temperature where the calibration can be carried out may vary from 18 °C to 30 °C. The flow rate of any test gas not condensing in this temperature range can be measured.

  20. Leak before break evaluation for main steam piping system made of SA106 Gr.C

    Energy Technology Data Exchange (ETDEWEB)

    Yang, Kyoung Mo; Jee, Kye Kwang; Pyo, Chang Ryul; Ra, In Sik [Korea Power Engineering Company, Seoul (Korea, Republic of)

    1997-04-01

    The basis of the leak before break (LBB) concept is to demonstrate that piping will leak significantly before a double ended guillotine break (DEGB) occurs. This is demonstrated by quantifying and evaluating the leak process and prescribing safe shutdown of the plant on the basis of the monitored leak rate. The application of LBB for power plant design has reduced plant cost while improving plant integrity. Several evaluations employing LBB analysis on system piping based on DEGB design have been completed. However, the application of LBB on main steam (MS) piping, which is LBB applicable piping, has not been performed due to several uncertainties associated with occurrence of steam hammer and dynamic strain aging (DSA). The objective of this paper is to demonstrate the applicability of the LBB design concept to main steam lines manufactured with SA106 Gr.C carbon steel. Based on the material properties, including fracture toughness and tensile properties obtained from the comprehensive material tests for base and weld metals, a parametric study was performed as described in this paper. The PICEP code was used to determine leak size crack (LSC) and the FLET code was used to perform the stability assessment of MS piping. The effects of material properties obtained from tests were evaluated to determine the LBB applicability for the MS piping. It can be shown from this parametric study that the MS piping has a high possibility of design using LBB analysis.