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로타 초음파 검사에서의 초음파 평가 결함크기와 실결함 크기와의 관계
성운학,김정태,박윤식 한국비파괴검사학회 2003 학술대회 논문집 Vol.- No.1
In order to evaluate the reliability of rotor forgings, it is very important to know the actual size of the defects in the rotor forgings. The determination of the defect size requires the accurate non-destructivc measurement. However, there may be some differences between the reported size with the ultrasonic non-destructive testing method and the actual size of defects. These differences may be a severe cause of errors in evaluation of rotor forgings. So, the calculated size with "Master Curve" considering safety factor, which is usually larger than the reported size, has been used in evaluation of rotor forgings. The relation between EFBH (Equivalent Flat Bottom Hole) size measured by non-destructive method and the actual size by destructive method in many rotors manufactured at Doosan was investigated. In this investigation, "Master Curve" compensating the differences between UT reported size and actual size of defects in our rotor forgings was obtainable. The applicability of this "Master Curve" as a way of calculating the actual defect sizc was also investigated. For the evaluation of rotor forgings, it is experted that this "Master Curve" may be used to determine the accurate actual size of defects.
남영현,성운학 韓國非破壞檢査學會 1999 한국비파괴검사학회지 Vol.19 No.4
본 논문에서는 로타(rotor)의 초음파 탐상 결과의 신뢰성을 향상시키기 위하여 수직탐촉자에 대한 교정시스템을 개발하였다. 본 시스템은 신호처리부 (오실로스코프, 스펙트럼 분석기, 송/수신기), 표준시험편, 프로그램으로 구성되어 있으며, 교정을 위한 신호처리는 높은 정밀도로 빠르게 수행할 수 있도록 구성되어 있다. 개발된 시스템을 이용하여 로타검사에 사용되고 있는 초음파 탐촉자를 교정하고 있으며, 신뢰성 있는 정밀도와 감도를 얻을 수 있었다. In this paper, the calibration system for contact transducer has been developed to improve the reliability of the inspection result of ultrasonic testing on rotors. This system consists of signal processing parts:(oscilloscope, spectrum analyzer, pulser/receiver). standard block, and user interface program. Signal processing for the calibration system was performed quickly with high accuracy. The developed system has been applied to a practical calibration of probe using the non-destructive testing on rotors, and demonstrated high sensitivity and precision.
초음파 자동 검사시스템의 개발과 오버레이 용접부의 결함검사
남영현,성운학 한국비파괴검사학회 2000 한국비파괴검사학회지 Vol.20 No.6
발전 및 산업설비에 사용되는 많은 압력용기는 저합금가강을 사용하여 제작되고 있다. 압력용기의 내면은 부식이 미치는 영향을 최소화하기 위하여 오스테나이트계 스테인리스강으로 덧살용접을 하고 있으나, 용접 층간의 계면에서 발생하고 있는 박리균열은 압력용기의 신뢰성에 중요한 변수가 되고 있다. 본 연구에서는 DSP를 사용하여 오버레이 용접부를 고속으로 검사할 수 있는 C-scan 시스템을 개발하였다. 본 시스템은 신호 처리부 (오실로스코프, 펄서.리시버, 디지타이저, DSP), 스케너, 프로그램 및 위치 제어부로 구성되어 있다. 개발된 시스템을 사용하여 실제 오버레이 용접부에 대한 초음파검사를 실시한 결과 고속으로 신뢰성 높은 검사결과를 얻을 수 있었다. Many pressure vessels for power and industrial plant are fabricated from low alloy carbon steels. The inner sides of pressure vessels are commonly weld-cladded with austenitic stainless steels to minimize problems of corrosive attack. Disbonding cracks are often detected at the transition region of welding interlayer, which is serious problem to reliability of pressure vessels. We have developed C-scan system to high speed inspection of overlay weld using DSP(digital signal processor). This system consists of signal processing parts (oscilloscope, pulser/receiver, digitizer, DSP), scanner, program and position controller. The developed system has been applied to a practical ultrasonic testing in overlay Weld, and demonstrated high speed with precision
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 핵분열생성물 누출탐상 Sipping 검사기술
신중철,양종대,성운학,류승우,박영우,Shin, Jung Cheol,Yang, Jong Dae,Sung, Un Hak,Ryu, Sung Woo,Park, Young Woo 한국압력기기공학회 2020 한국압력기기공학회 논문집 Vol.16 No.2
When a damage occurs in the nuclear fuel burning in the reactor, fission products that should be in the nuclear fuel rod are released into the reactor coolant. In this case, sipping test, a series of non-destructive inspection methods, are used to find leakage in nuclear fuel assemblies during the power plant overhaul period. In addition, the sipping test is also used to check the integrity of the spent fuel for moving to an intermediate dry storage, which is carried out as the first step of nuclear decommissioning, . In this paper, the principle and characteristics of the sipping test are described. The structure of the sipping inspection equipment is largely divided into a suction device that collects fissile material emitted from a damaged assembly and an analysis device that analyzes their nuclides. In order to make good use of the sipping technology, the radioactive level behavior of the primary system coolant and major damage mechanisms in the event of nuclear fuel damage are also introduced. This will be a reference for selecting an appropriate sipping method when dismantling a nuclear power plant in the future.
신중철,양종대,성운학,류승우,박영우 한국압력기기공학회 2020 한국압력기기공학회 논문집 Vol.16 No.1
As the management plan for domestic spent nuclear fuel is delayed, the storage of the operating nuclear power plant is approaching saturation, and the Kori 1 Unit that has reached its end of operation life is preparing for the dismantling plan. The first stage of dismantling is the transfer of spent nuclear fuel stored in storage at plants. The spent fuel management process leads to temporary storage, interim storage, reprocessing and permanent disposal. In this paper, the technical issues to be considered when transporting spent fuel in this process are summarized. The spent fuels are treated as high-level radioactive waste and strictly managed according to international regulations. A series of integrity tests are performed to demonstrate that spent fuel can be safely stored for decades in a dry environment before being transferred to an intermediate storage facility. The safety of spent fuel transport container must be demonstrated under normal transport conditions and virtual accident conditions. IAEA international standards are commonly applied to the design of transport containers, licensing regulations and transport regulations worldwide. In addition, each country operates a physical protection system to reduce and respond to the threat of radioactive terrorism.