초음파와 Barkhausen Noise에 의한 강의 연.취성천이온도 예측

남영현,성운학,Nam, Young-Hyun,Seong, Un-Hak 대한기계학회 1999 大韓機械學會論文集A Vol.23 No.7

It is advantageous to use an NDE method to assess the mechanical properties of materials since the conventional method is time-consuming and sometimes requires cutting of sample from the material/component. This paper shows that the ultrasonic and the Barkhausen noise(BHN) methods can be used to accurately characterize forged reactor vessels. The attenuation coefficient of the ultrasonic wave was changed with heat treatment temperature and condition[as-quenched, tempered, PWHT]. The RMS[root mean square] voltage of Barkhausen noise depended on heat treatment temperature and conditions. The fracture appearance transition temperature(FATT) can be predicted using nondestructive evaluation methods.

사용후핵연료 건식저장용기 건전성검사 기술

신중철(Jung CHeol Shin),성운학(Un Hak Seong),류승유(Sung Woo Ryu),박영우(Young Woo Park) 한국비파괴검사학회 2021 한국비파괴검사학회 춘계학술대회 초록집 Vol.2021 No.6

DSP를 이용한 초음파 C-scan 시스템 개발

남영현(Young Hyun Nam),성운학(Un Hak Seong),김정태(Jeong Tae Kim) Korean Society for Precision Engineering 1999 한국정밀공학회지 Vol.16 No.7

Shrunk-on Type 저압 터빈 로터의 가동중검사를 위한 초음파검사 시스템 개발

박준수(Joon-Soo Park),성운학(Un-Hak Seong),유승우(Sung-Woo Ryu) 한국비파괴검사학회 2009 한국비파괴검사학회지 Vol.29 No.2

터빈은 원자력발전소의 주요기기로서 고온ㆍ고압하에서 고속회전으로 인해 신뢰성 있는 검사가 요구된다. 터빈의 가동중검사의 경우 블레이드가 조립된 상태에서 검사가 수행되며 구조적 복잡성으로 인하여 탐촉자의 접근이 제한되며, 신호 해석이 매우 어렵다. 본 연구에서는 신뢰성 높은 신호해석을 위하여 실제 터빈과 크기 및 형상이 동일한 mock-up을 제작하였다. 터빈의 key와 내표면부의 결함탐상을 위해 pulse-echo 및 TOFD 기법을 개발하였고, dovetail 검사를 위하여 위상배열 초음파탐상기법을 개발하였다. 개발된 기법들을 가동중 터빈 검사에 효율적으로 적용하기 위해 자동화 검사 scanner를 제작하였으며, 현장적용을 통하여 신뢰성을 검증하였다. Turbine, which is one of major components in nuclear power plants, requires reliable nondestructive inspections. But, accessibility of transducers is limited and interpretation of acquired signals is not easy at all due to the complication. So, in this study, we have fabricated mock-up specimens of real size and shape. we applied pulse-echo method and time-of-flight diffraction(TOFD) method for precise inspection of turbine key and wheel bore. And phased array ultrasonic testing method was adopted for wheel dovetail of turbines by using mock-up. Furthermore, an automatic scanner system was developed for in-service inspection of the developed methods.

초음파 핵연료 세정장비의 시스템 구성과 제거된 크러드의 정량적 무게 측정법

신중철(Jung Cheol Shin),이학윤(Hak Yun Lee),성운학(Un Hak Seong),주영종(Yeong Jong Joo),김용찬(Yong Chan Kim),한욱진(Wook Jin Han) 한국압력기기공학회 2024 한국압력기기공학회 논문집 Vol.20 No.1

Crud is a corrosion deposit that forms in equipments and piping of nuclear reactor’s primary systems. When crud circulates through the reactor’s primary system coolant and adheres to the surface of the nuclear fuel cladding tube, it can lead to the Axial Offset Anomaly (AOA) phenomenon. This occurrence is known to potentially reduce the output of a nuclear power plant or to necessitate an early shutdown. Consequently, worldwide nuclear power plants have employed ultrasonic cleaning methods since 2000 to mitigate crud deposition, ensuring stable operation and economic efficiency. This paper details the system configuration of ultrasonic nuclear fuel cleaning equipment, outlining the function of each component. The objective is to contribute to the local domestic production of ultrasonic nuclear fuel cleaning equipment. Additionally, the paper introduces a method for accurately measuring the weight of removed crud, a crucial factor in assessing cleaning effectiveness and providing input data for the BOA code used in core safety evaluations. Accurate measurement of highly radioactive filters containing crud is essential, and weighing them underwater is a common practice. However, the buoyancy effect during underwater weighing may lead to an overestimation of the collected crud’s weight. To address this issue, the paper proposes a formula correcting for buoyancy errors, enhancing measurement accuracy. This improved weight measurement method, accounting for buoyancy effects in water, is expected to facilitate the quantitative assessment of filter weights generated during chemical decontamination and system operations in nuclear power plants.

원자력발전 고방사선구역 소구경 노즐에 대한 자동화검사 기술

류승우(Sung Woo Ryu),윤기봉(Kee Bong Yoon),전규민(Gyu Min Jeon),성운학(Un Hak Seong) 한국비파괴검사학회 2016 한국비파괴검사학회지 Vol.36 No.6

원자력발전소의 노후화에 따른 이종금속용접부에서 결함 발생 사례가 지속적으로 보고되고 있으며, 국내에서도 원자력발전소 가동연수 증가에 따라 이종금속부에 결함 발생도 점점 증가할 것으로 판단된다. 국내에서는 증기발생기 배수 노즐 이종금속용접부, 원자로냉각재계통(RCS) 고온관 시료 채취 노즐에서 결함사례가 보고되었고, 원자력발전소의 인력 접근이 제한적인 고방사선구역 내 소구경 노즐의 이종금속용접부에 대한 검사 시 인력 투입을 최소화 하는 신뢰성 있는 자동화 비파괴검사 가능 기술 및 시스템 개발 필요성이 증대되고 있다. 본 연구에서는 원자력발전소의 소구경 노즐 결함 검출을 위해 1) beam simulation을 통한 최적 검사 탐촉자 설계, 2) 소구경 이종용접부 검사용 multi-directions UT 최적 검사기술, 3) 원격제어 automatic inspection system을 개발하였으며, 표준결함시편을 이용하여 개발된 기술 및 시스템의 결함 검출능을 검증하였다. 개발된 최적기술과 시스템은 실제 발전소에서 발생된 결함 (RCS 고온관 시료 채취 노즐)에 대한 검사에 적용하여 결함을 검출함으로써 개발 검사 기술 및 시스템의 적합성이 검증되었다. 개발된 기술은 원전의 다양한 소구경 건전성 평가에 활용함으로써 원자력발전 안전성 확보에 기여할 수 있을 것으로 기대된다. Defects in dissimilar metal welds are reported to be on the increase during the operating lifespan and aging of nuclear power plants. In Korea, reported cases of defects due to dissimilar metal welds include the drain nozzle of a steam generator and RCS hot tube sampling nozzles. Therefore, there is an urgent need to develop a reliable automated nondestructive inspection technique and a system for the inspection of dissimilar metal welds of small diameter nozzles in a high radiation area of a nuclear power plant. In this study, to ensure effective defect inspection of small diameter nozzles (RCS high-temperature tube sampling nozzle) of a nuclear power plant, three different methods were developed. These include: (1) optimum inspection probe design by beam simulation, (2) multi-directions UT optimum inspection technique for the inspection of small diameters of different welded parts, and (3) remote control automatic inspection system. The developed technique and systems have been verified to be suitable for use in the inspection of defects in smaller diameter nozzles in nuclear power plants.

위상배열 초음파 결함 산정 기법 연구

김훈희(Hun-Hee Kim),송성진(Sung-Jing Song),김학준(Hak-Joon Kim),성운학(Un-Hak Seong),지병하(Byung-Ha Chi),박준수(Joon-Soo Park) 대한기계학회 2010 대한기계학회 춘추학술대회 Vol.2010 No.11

Flaw sizing is very important issue in phased array ultrasonic nondestructive evaluation of materials, components and structures. Especially, cracks are very often encountered in structural components necessitating reliable procedure for determining their size. Therefore, robust and reliable flaw sizing methods are strongly needed. To address such a need, For development of model based flaw sizing method for phased array ultrasonic testing, We need that fabrication of EDM Notches with various size and Simulation of PAUT beam field on cracks using Rayleigh Sommerfeld Integral, Calculation of ultrasonic energy with variation of crack size, Verification of proposed method by the comparison of experimental results. In this paper, principal of flaw sizing methods using PAUT will describe briefly and performance of the methods will be presented

원전 터빈로터 중심공 결함 검출을 위한 비파괴 센서 개발 연구

김훈희(Hun-Hee Kim),송성진(Sung-Jing Song),김학준(Hak-Joon Kim),성운학(Un-Hak Seong),지병하(Byung-Ha Chi),박준수(Joon-Soo Park),김동규(Dong-kyu Kim),박대진(Dae-Jin Park) 대한기계학회 2010 대한기계학회 춘추학술대회 Vol.2010 No.11

Safety and reliability of nuclear power plants is one of important issues. Especially, turbine rotor is important components in nuclear power plants. To insure integrity of turbine rotors, integrated nondestructive evaluation techniques are applied. However, optimization of NDE sensors used in integrates NDE system is required to improve probability of detection. Thus, in this paper, determination of design parameter for eddy current, magnetic flux leakage, and phased array ultrasonic sensors based on simulation technique was performed. In this presented, simulation results with variation of design parameters are presented. And, determine optimized design parameter for PAUT, ECT, MFL sensors will be discuss.

원자로 BMI 노즐 검사를 위한 자동화 비파괴검사 시스템 개발

박준수(Joon Soo Park),이원근(Won Kun Lee),한원진(Won Jin Han),이선호(Sun Ho Lee),성운학(Un Hak Seong) 한국비파괴검사학회 2013 한국비파괴검사학회지 Vol.33 No.1

원자로 BMI 노즐은 원자력발전 설비의 운영을 위한 핵심요소 중 하나이며 하부헤드에 설치되어 있다. 상부헤드에 비해 비교적 저온영역에 있지만 최근 외국사례에 비추어 볼 때 PWSCC의 발생 가능성이 크기 때문에 가동중 비파괴검사가 반드시 필요하다. 그러나 BMI 노즐은 원자로 하부에 있기 때문에 고방사선 구역이며 원자로 내부는 붕산수로 채워져 있기 때문에 접근이 매우 어렵다. 본 연구에서 BMI 노즐 검사를 위하여 TOFD를 이용한 탐촉자를 개발하였고, 자동화검사를 위해 내방수 기능을 가진 스캐너를 개발하였다. 또한, BMI 노즐과 동일한 재질 및 형상으로 인공결함시험편을 제작하여 자동화 비파괴검사 시스템의 성능검증을 수행하였다. BMI nozzles in bottom head of the nuclear vessel are one of major components in nuclear power plants. The BMI nozzles have high possibility to generate PWSCC(primary water stress corrosion crack) according to recent foreign case although operation temperature is lower then the upper head of the nuclear vessel. Thus, nondestructive inspection of the BMI nozzles is required. But, inspection of BMI nozzles is not easy since the BMI nozzles placed in high radiated area and inside the nozzles filled with boric acid. Thus, in this study, a TOFD transducer for inspection of BMI and automated scanner system with water were developed. Also, validation of performance of the developed transducer and system are performed using specimens with artificial defects.