• Title/Summary/Keyword: Leak Detection

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Evaluation of Piping Failure Probability of Reactor Coolant System in Kori Unit 1 Considering Stress Corrosion Cracking (응력부식균열을 고려한 고리 1호기 원자로냉각재계통의 배관 파손확률 평가)

  • Park, Jeong Soon;Choi, Young Hwan;Park, Jae Hak
    • Transactions of the Korean Society of Pressure Vessels and Piping
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    • v.6 no.1
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    • pp.43-49
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    • 2010
  • The piping failure probability of the reactor coolant system in Kori unit 1 was evaluated considering stress corrosion cracking. The P-PIE program (Probabilistic Piping Integrity Evaluation Program) developed in this study was used in the analysis. The effect of some variables such as oxygen concentration during start up and steady state operation, and operating temperature, which are related with stress corrosion cracking, on the piping failure probabilities was investigated. The effects of leak detection capability, the size of big leak, piping loops, and reactor types on the piping failure probability were also investigated. The results show that (1) LOCA (loss of coolant accident) probability of Kori unit 1 is extremely low, (2) leak probability is sensitive to oxygen concentration during steady state operation and operating temperature, while not sensitive to the oxygen concentration during start up, and (3) the piping thickness and operating temperature play important roles in the leak probabilities of the cold leg in 4 reactor types having same inner diameter.

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Noise Generation by Water-Sodium Reaction and its Absorption on Hydrogen Bubbles for KALIMER Steam Generator (칼리머 증기발생기에서 물-소듐 반응에 의한 소음 발생과 수소 기포의 소음 흡수)

  • Kim, Tae-Joon;Yughay, Valeri S.;Hwang, Sung-Tai
    • Proceedings of the Korean Society for Noise and Vibration Engineering Conference
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    • 2000.06a
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    • pp.1829-1835
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    • 2000
  • The experimental results of sodium-water reaction noise measurement in frequency range $1{/sim}200kHz$ are presented. The experiments of noise generation under the condition of sodium test facility, water leak rate $0.01{\sim}1.2g/s$ and temperature of sodium $250{\sim}500^{\circ}C$, were carried out. From theoretical study it is noted that the noise resonant attenuation on hydrogen bubbles in liquid sodium plays the significant role for leak noise spectra formation. Interaction of leak noise and hydrogen bubbles in sodium being accompanied by thermal, emission and viscosity energy dissipation was studied. Acoustic noise spectra were investigated from point of view of water leak detection in sodium/water steam generator. The results of sodium-water reaction noise absorption on hydrogen bubbles in liquid sodium by temperature $250{\sim}500^{\circ}C$ are presented. The theoretical model of noise absorption using the coefficients of attenuation was developed. From calculation the coefficients of attenuation were estimated.

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Mobile Robot-based Leak Detection and Tracking System for Advanced Response and Training to Hazardous Materials Incidents (화학물질 저장시설의 사고대응 및 훈련을 위한 로봇기반 누출감지 및 추적시스템)

  • Park, Myeongnam;Kim, Chang Won;Kim, Tae-Ok;Shin, Dongil
    • Journal of the Korean Institute of Gas
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    • v.23 no.2
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    • pp.17-27
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    • 2019
  • In recent years, dangerous materials and gas leak accidents have been frequently occurred. The hazardous materials storage facility accidents are not rapidly controlled when a leak is detected, unlike other chemical plants can be controled. Externally, the human has to approach and respond to the source of leaking directly. As a result, the human and material damage are likely to larger result in the process. The current approach has been passive response after ringing the alarm. In this study, the suggested tracking system of the leak resource is designed system to track the resource actively by utilizing the mobile sensor robot platform, which can be made easily through recent rapid development technology, is verified through prototype system. Thus, a suggested system should pave the way for minimizing the spread and damage of the accident based on the exact site situation of the initial leak and quick and early measures.

Application of Transient and Frequency Analysis for Detecting Leakage of a Simple Pipeline (누수탐지를 위한 천이류와 주착수분석 적용 연구)

  • Kim, Hyung-Geun;Kim, Hyun-Soo;Lee, Mi-Hyun;Kim, Sang-Hyun
    • Journal of Korean Society of Environmental Engineers
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    • v.27 no.10
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    • pp.1065-1071
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    • 2005
  • Many techniques of leak detection in pipeline systems have developed based on the propagation wave speeds and wave attenuation. In this paper, the transient analysis methodology is used for calculating the wave speed in the plastic pipe and a frequency analysis methodology is developed for leakage detection in water pipe networks. Data acquisition system for pressurized pipeline system were designed md fabricated to obtain high frequency pressure data. The methodology properly handles the unavoidable uncertainties in measurement and modeling error. Based on information from head pressure test data, it provides leak prediction capability from the transient events with leakage.

Signal processing method of bubble detection in sodium flow based on inverse Fourier transform to calculate energy ratio

  • Xu, Wei;Xu, Ke-Jun;Yu, Xin-Long;Huang, Ya;Wu, Wen-Kai
    • Nuclear Engineering and Technology
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    • v.53 no.9
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    • pp.3122-3125
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    • 2021
  • Electromagnetic vortex flowmeter is a new type of instrument for detecting leakage of steam generator, and the signal processing method based on the envelope to calculate energy ratio can effectively detect bubbles in sodium flow. The signal processing method is not affected by changes in the amplitude of the sensor output signal, which is caused by changes in magnetic field strength and other factors. However, the detection sensitivity of the electromagnetic vortex flowmeter is reduced. To this end, a signal processing method based on inverse Fourier transform to calculate energy ratio is proposed. According to the difference between the frequency band of the bubble noise signal and the flow signal, only the amplitude in the frequency band of the flow signal is retained in the frequency domain, and then the flow signal is obtained by the inverse Fourier transform method, thereby calculating the energy ratio. Using this method to process the experimental data, the results show that it can detect 0.1 g/s leak rate of water in the steam generator, and its performance is significantly better than that of the signal processing method based on the envelope to calculate energy ratio.

Role of Barium Swallow in Diagnosing Clinically Significant Anastomotic Leak following Esophagectomy

  • Roh, Simon;Iannettoni, Mark D.;Keech, John C.;Bashir, Mohammad;Gruber, Peter J.;Parekh, Kalpaj R.
    • Journal of Chest Surgery
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    • v.49 no.2
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    • pp.99-106
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    • 2016
  • Background: Barium swallow is performed following esophagectomy to evaluate the anastomosis for detection of leaks and to assess the emptying of the gastric conduit. The aim of this study was to evaluate the reliability of the barium swallow study in diagnosing anastomotic leaks following esophagectomy. Methods: Patients who underwent esophagectomy from January 2000 to December 2013 at our institution were investigated. Barium swallow was routinely done between days 5-7 to detect a leak. These results were compared to clinically determined leaks (defined by neck wound infection requiring jejunal feeds and or parenteral nutrition) during the postoperative period. The sensitivity and specificity of barium swallow in diagnosing clinically significant anastomotic leaks was determined. Results: A total of 395 esophagectomies were performed (mean age, 62.2 years). The indications for the esophagectomy were as follows: malignancy (n=320), high-grade dysplasia (n=14), perforation (n=27), benign stricture (n=7), achalasia (n=16), and other (n=11). A variety of techniques were used including transhiatal (n=351), McKeown (n=35), and Ivor Lewis (n=9) esophagectomies. Operative mortality was 2.8% (n=11). Three hundred and sixty-eight patients (93%) underwent barium swallow study after esophagectomy. Clinically significant anastomotic leak was identified in 36 patients (9.8%). Barium swallow was able to detect only 13/36 clinically significant leaks. The sensitivity of the swallow in diagnosing a leak was 36% and specificity was 97%. The positive and negative predictive values of barium swallow study in detecting leaks were 59% and 93%, respectively. Conclusion: Barium swallow is an insensitive but specific test for detecting leaks at the cervical anastomotic site after esophagectomy.

Leakage detection and management in water distribution systems

  • Sangroula, Uchit;Gnawali, Kapil;Koo, KangMin;Han, KukHeon;Yum, KyungTaek
    • Proceedings of the Korea Water Resources Association Conference
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    • 2019.05a
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    • pp.160-160
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    • 2019
  • Water is a limited source that needs to be properly managed and distributed to the ever-growing population of the world. Rapid urbanization and development have increased the overall water demand of the world drastically. However, there is loss of billions of liters of water every year due to leakages in water distribution systems. Such water loss means significant financial loss for the utilities as well. World bank estimates a loss of $14 billion annually from wasted water. To address these issues and for the development of efficient and reliable leakage management techniques, high efforts have been made by the researchers and engineers. Over the past decade, various techniques and technologies have been developed for leakage management and leak detection. These include ideas such as pressure management in water distribution networks, use of Advanced Metering Infrastructure, use of machine learning algorithms, etc. For leakage detection, techniques such as acoustic technique, and in recent yeats transient test-based techniques have become popular. Smart Water Grid uses two-way real time network monitoring by utilizing sensors and devices in the water distribution system. Hence, valuable real time data of the water distribution network can be collected. Best results and outcomes may be produced by proper utilization of the collected data in unison with advanced detection and management techniques. Long term reduction in Non Revenue Water can be achieved by detecting, localizing and repairing leakages as quickly and as efficiently as possible. However, there are still numerous challenges to be met and future research works to be conducted in this field.

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Smart Safety Helmet Using Arduino (아두이노를 이용한 스마트 안전모)

  • Lee, Dong-Gun;Kim, Won-Boem;Kim, Joong-Soo;Lim, Sang-Keun;Kong, Ki-Sok
    • The Journal of the Institute of Internet, Broadcasting and Communication
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    • v.19 no.1
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    • pp.77-83
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    • 2019
  • Major causes of industrial accidents include falls and gas leak. The existing safety helmet and smart device combination products are focused on convenience, so the functions to prevent such accidents are insufficient. We developed a smart helmet focusing on fall accident detection and gas leak detection. We also developed management system to manage workers efficiently. Its core function is to detect dangerous conditions of employees, to communicate with managers and to confirm the situations of workers. The effectiveness of the combustible gas measurement capability was verified through experiments. However, since a significant amount of power consumption is founded due to continuous operation of the board and the sensor, countermeasures such as replacing with a large capacity battery are required.