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이상국(S. G. Lee),추기영(G. Y. Chu) 한국동력기계공학회 2005 한국동력기계공학회 학술대회 논문집 Vol.- No.-
The purpose of this study is to verify availability of the acoustic emission in-situ monitoring method to the internal leak and operating conditions of the major valves at nuclear power plants. In this study, acoustic emission tests are performed when the pressurized temperature water and steam flowed through glove valve(main steam dump valve) and check valve(main steam outlet pump check valve) on the normal size of 12 and 18". The valve internal leak monitoring system for practical field was designed. The acoustic emission method was applied to the valves at the site, and the background noise was measured for the abnormal plant condition. To improve the reliability, a judgment of leak on the system was used various factors which are AE parameters, trend analysis, frequency analysis, voltage analysis and amplitude analysis of acoustic signal emitted from the valve operating condition internal leak.
원자력발전소 펌프 메카니컬씰 성능저하 변수 측정에 관한 연구
이상국(S. G. Lee),이도환(D. H. Lee) 한국동력기계공학회 2009 한국동력기계공학회 학술대회 논문집 Vol.2009 No.11
Mechanical seals are widely used in many typed of rotating power plant equipment, especially pumps of various sizes and pressure ratings. Even though mechanical seals are capable of providing reliable long-term service with proper consideration to design, application, installation, and maintenance, they still exhibit unsatisfactory performance, short life, and unpredictable failures in some applications. As such, mechanical seals have a significant influence on the reliability of power plant equipment. Thus, the purpose of this study is to analyze the failure modes and parameters of mechanical seals and its mechanism that are responsible for the failures. Through this study, we are going to improve the measurement method for detecting of degradation conditions of mechanical seal system.
이상국(S. G. Lee),김영범(Y. B. Kim) 한국동력기계공학회 2007 한국동력기계공학회 학술대회 논문집 Vol.- No.-
Leakage would happen because of the damage of high temperature and high-pressure valve in nuclear power plant. condition based prevention maintenance is essential by using the suitable method based on local condition. Energy loss prevention can prevent from an accurate test, Local actually and ability. The methods of test for high energy fluid leakage at present are analysis of △T, AE(Acoustic Emission) analysis, and thermal image. The result for test of secondary system in nuclear power plant Unit reveals that the AE occurred clearly in leakage situation, but thermal image didn't occur. It is identified that leakage is occurred when the orifice located front and back of valve operates. It shows that making a impatient judgment by using the single method if it is leakage is containing uncertainty. So we think that using the Multi-Measuring method is more sound judgment than single-measuring method.
이상국(S. G. Lee),박중혁(J. H Park),Y. B. Kim 한국동력기계공학회 2006 한국동력기계공학회 학술대회 논문집 Vol.- No.-
The purpose of this study is to verify availability of the acoustic emission in-situ diagnosis method to the internal leak and operating conditions of the major valves at nuclear power plants. In this study, acoustic emission tests are performed when the pressurized high temperature steam flowed through gate valve(1st stage reheater valve) and glove valve/main steam dump valve) on the normal size of 4 and 8". The valve internal leak diagnosis system for practical field was designed. The acoustic emission method was applied to the valves at the site, and the background noise was measured for the abnormal plant condition. To improve the reliability, a judgment of leak on the system was used various factors which are AE parameters, trend analysis, signal level analysis and RMS(root mean square) analysis of acoustic signal emitted from the valve operating condition internal leak.