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최명환(Choi, M.H.),김지호(Kim, J.H.),허형(Huh, H.),유제용(Yu, J.Y.) 한국소음진동공학회 2010 한국소음진동공학회 논문집 Vol.20 No.7
A control element drive mechanism(CEDM) is a reactor regulating system, which inserts, withdraws or maintains a control rod containing a neutron absorbing material within a reactor core to control the reactivity of the core. The ball-screw type CEDM for the integral reactor has a spring-damper system to reduce the impact force due to the scram of the CEDM. This paper describes the experimental results to obtain the drop and damping characteristics of the CEDM. The drop tests are performed by using a drop test rig and a facility. A drop time and a displacement after an impact are measured using a LVDT. The influences of the rod weight, the drop height and the flow area of hydraulic damper on the drop and damping behavior are also estimated on the basis of test results. The drop time of the control element is within 4.5s to meet the design requirement, and the maximum displacement is measured as 15.6 mm. It is also found that the damping system using a spring-hydraulic damper plays a good damper role in the CEDM.
허형,박치승,홍순신,박종현 韓國非破壞檢査學會 1989 한국비파괴검사학회지 Vol.9 No.1
Since the nuclear power plants in Korea have been operated in 1979, the nondestructive testing(NDT) of pressure vessels and/or piping welds plays an important role for maintaining the safety and integrity of the plants. Ultrasonic method is superior to the other NDT method in the viewpoint of the detectability of small flaw and accuracy to determine the locations, sizes, orientations, and shapes. As the service time of the nuclear power plants is increased, the radiation level from the components is getting higher. In order to get more quantitative and reliable results and secure the inspector from the exposure to high radiation level, automation of the ultrasonic equipments has been one of the important research and development(R & D) subject. In this research, it was attempted to visualize the shape of flaws presented inside the specimen using a Modified C-Scan technique. In order to develope Modified C-Scan technique, an automatic ultrasonic scanner and a module to control the scanner were designed and fabricated. IBM-PC/XT was interfaced to the module to control the scanner. Analog signals from the SONIC MARK II were digitized by Analog-Digital Converter(ADC 0800) for Modified C-Scan display. A computer program has been developed and has capability of automatic data acquisition and processing from the digital data, which consist of maximum amplitudes in each gate range and location. The data from Modified C-Scan results was compared with shape from artificial defects using the developed system. Focal length of focused transducer was measured. The automatic ultrasonic equipment developed through this study is essential for more accurate, reliable, and repeatable ultrasonic experiments. If the scanner are modified to meet to appropriate purpose, it can be applied to automation of ultrasonic examination of nuclear power plants and helpful to the research on ultrasonic characterization of the materials.
핵연료 채널과 LIN 간격 측정을 위한 전자기 분포해석 및 원격장 와전류 신호 모델링
이동훈,정현규,정용무,허형,이윤상 한국비파괴검사학회 2004 학술대회 논문집 Vol.- No.-
Fuel channels including pressure tube(PT) and calandria tube(CT) are important components of pressurized heavy water reactor(PHWR). A sagging of fuel channel increases by heat and radiation exposure with the increasing operation time. The contact of fuel channel to liquid injection nozzle(LIN) is thus a critical issue in power plant safety. In order to solve this safety issue, the electromagnetic technique was applied to compliment the present inspection technology. Electromagnetic fields were investigated for the gap measurement between CT and LIN using FEM computer modeling. We calculated the electromagnetic fields, such as, magnetic flux density, current density near the fuel channel and checked the adaptability of RFEC technology. The RFEC Signals using the volume integral method(VIM) were simulated for obtaining the optimal inspection parameters, including frequency, inter-coil spacing, coil size and configuration. Finally, we development the remote field eddy current sensor that can CT/LIN gap measurement efficiently
교차 배열된 지르코늄관 간격 측정을 위한 전압 평면에서의 신호해석
정현규,이윤상,이동훈,허형,정용무 한국비파괴검사학회 2003 학술대회 논문집 Vol.- No.1
The eddy current(EC) signals were evaluated for gap measurement of cross aligned zirconium tubes for preventing the contact which might be the safety concern. Liquid lnjection Nozzle(LIN) tube and Calandria tube(CT) were cross-aligned horizontally and LIN could be detected by inserting the EC probe into pressure tube (PT). Signal analysis on the voltage plane was applied to describe the position and shape of possible defects using several frequencies. Test variables are lift-off, PT thickness variation, and gap variation between PT and CT All the EC measurements in the laboratory were done in variance with the gap spacings and showed the possibility to evaluate the gap between CT. and LIN tube by analyzing the signal on voltage plane. Electromagnetic technique could be a potential tool for inspecting the inter-tube gap in CANDU reactor.