• 한국정밀공학회:학술대회논문집
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• 한국정밀공학회 2004년도 추계학술대회 논문집
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• pp.60-63
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• 2004

An innovative in-core neutron flux mapping system has been developed and applied successfully for service in a commercial pressurized water reactor. With the benefit of double indexing path selector (Dip $s^{ⓡ}$) mechanism, the reliability of the detector drive system has been improved five times higher than that of conventional systems, and the problems caused by the serious friction generated between the detector cable and guide tubing has been solved completely because the Dip $s^{ⓡ}$ architecture allows the detector guide tubings to have larger curvature and shorter length in nature. The simple and fast maintenance is particularly emphasized in the detector drive system to secure minimum radiation exposure to the maintenance personnel by optimizing the number of components and providing easy access to the components. The programmable logic controller based digital controller with Window $s^{ⓡ}$ based operator s console provides fully automated and user friendly operation and maintenance support means.

• 한국정밀공학회:학술대회논문집
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• 한국정밀공학회 2006년도 추계학술대회 논문집
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• pp.363-364
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• 2006

• 대한전기학회:학술대회논문집
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• 대한전기학회 2005년도 학술대회 논문집 정보 및 제어부문
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• pp.225-227
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• 2005

The in-core neutron Flux Mapping System in a pressurized water reactor yields information on the neutron flux distribution in the reactor core at selected core locations by means of movable detectors. The obtained data are used to verify the reactor core design parameters. The detector cables run through guide tubes(thimbles), and typically thirty-six to fifty-eight thimbles are allocated in the reactor depending on the number of fuel assemblies. These thimbles are inserted into nuclear fuel assemblies through conduits connected from the bottom of the reactor vessel to a seal table. During the plant refueling outage period, the thimbles are withdrawn up to 4m from the seal table, the height of a nuclear fuel. In spite of their importance, however, the thimble handling work has been performed by only human operators. In addition, its efficiency is very low due to narrow working environments on the seal table, thereby resulting in the excessive radiation exposure of maintenance personnel. To solve these problems, a new thimble handling equipment for in-core flux mapping system was developed, and we confirmed its effectiveness through experiments.

• Nuclear Engineering and Technology
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• 제50권1호
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• pp.203-210
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• 2018

As the modernization of the nuclear instrumentation system progresses, research reactors have adopted digital wide-range neutron power measurement (DWRNPM) systems. These systems typically monitor the neutron flux across a range of over 10 decades. Because neutron detectors only measure the local neutron flux at their position, the local neutron flux must be converted to total reactor power through calibration, which involves mapping the local neutron flux level to a reference reactor power. Conventionally, the neutron power range is divided into smaller subranges because the neutron detector signal characteristics and the reference reactor power estimation methods are different for each subrange. Therefore, many factors should be considered when preparing the calibration procedure for DWRNPM channels. The main purpose of this work is to serve as a reference for performing the calibration of DWRNPM systems in research reactors. This work provides a comprehensive overview of the calibration of DWRNPM channels by describing the configuration of the DWRNPM system and by summarizing the theories of operation and the reference power estimation methods with their associated calibration procedure. The calibration procedure was actually performed during the commissioning of an open-pool type research reactor, and the results and experience are documented herein.

• 한국원자력학회:학술대회논문집
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• 한국원자력학회 1996년도 춘계학술발표회논문집(4)
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• pp.101-106
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• 1996

For the application of the neutron flux mapping, an accurate calculation of the sensitivity is required because the sensitivity is proportional to the neutron flux density. Sensitivity is defined as the current per unit length per unit neutron flux and it mainly depends on the depression factor(f), the escape probability from the emitter($\varepsilon$1) and the charge build-up factor of the insulator layer(c). A Monte Carlo simulation was accomplished to calculate the sensitivity of rhodium emitter material and alumina(Al$_2$O$_3$) insulator with a cylindrical geometry, based on the (n,${\beta}$) interaction and on other interaction including the secondary electron generation for the more accurate estimation of the sensitivity. From the simulation results, factors fur the sensitivity were accurately calculated and compared with other theoretical and experimental values. In addition, the sensitivity linearly increases and saturates as the emitter radius increases. The accomplished method is useful in the analysis for the change of SPND sensitivity as a function of burn-up and in the optimum design of SPND.

• 한국원자력학회:학술대회논문집
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• 한국원자력학회 2004년도 추계학술발표회 발표논문집
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• pp.631-632
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• 2004

• Nuclear Engineering and Technology
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• 제52권12호
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• pp.2852-2859
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• 2020

This paper deals with the simulation-based design optimization and experimental validation of the characteristics of an in-core silver Self-Powered Neutron Detector (SPND). Optimized dimensions of the SPND are determined by combining Monte Carlo simulations and analytical methods. As a first step, the Monte Carlo transport code MCNPX is used to follow the trajectory and fate of the neutrons emitted from an external source. This simulation is able to seamlessly integrate various phenomena, including neutron slowing-down and shielding effects. Then, the expected number of beta particles and their energy spectrum following a neutron capture reaction in the silver emitter are fetched from the TENDEL database using the JANIS software interface and integrated with the data from the first step to yield the origin and spectrum of the source electrons. Eventually, the MCNPX transport code is used for the Monte Carlo calculation of the ballistic current of beta particles in the various regions of the SPND. Then, the output current and the maximum insulator thickness to avoid breakdown are determined. The optimum design of the SPND is then manufactured and experimental tests are conducted. The calculated design parameters of this detector have been found in good agreement with the obtained experimental results.

• 대한전기학회:학술대회논문집
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• 대한전기학회 2006년도 제37회 하계학술대회 논문집 D
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• pp.1995-1996
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• 2006

검출기 안내관은 노내 핵계측 계통의 중성자 분포 측정을 위한 이동형 검출기의 이동경로를 제공할 뿐만 아니라 원자로 냉각수 계통의 압력경계를 유지하는 안전성 등급의 중요한 설비이다. 그러나, 인출과 삽입을 위한 검출기 안내관 취급은 의외로 낙후되어 작업자의 인력에만 의존하고 있는 실정이며, 원자로 격납용기 내부에 위치한 고방사선 지역에서 작업이 수행되고 있는 실정이다. 따라서 노내 핵계측 계통의 검출기 안내관의 안정적인 관리를 위해 검출기 안내판을 일정한 힘으로 인출하고 삽입할 수 있는 자동화시스템의 개발이 이루어지고 있다. 전력연구원에서 개발한 안내관 취급기구는 롤러에 의해 안내관을 파지하고, DC 모터 구동에 의해 안내관을 인출하고 삽입하는데, 본 논문에서는 안내관 취급 기구의 제어 시스템 구성과, 롤러와 안내관 사이에 발생하는 슬립을 고려한 제어기 구조를 제안하고, 실험을 통해 구현한 제어 시스템의 효용성을 보인다.

• 조명전기설비학회논문지
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• 제14권4호
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• pp.1-7
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• 2000

본 논문에서 원전의 핵연료 다발의 중섬자속을 측정할 수 있는 노내중성지속 감시계통의 구동모터를 제어하기 위한 스위치의 오동작 원인 분석 및 이 문제를 해결하기 위한 방안을 제시하고자 한다. 노내중성자속 감시계동은 검출기 안내관을 통해 검출기가 노심으로 삽입되거나 인출될 경우 접점선호를 발생하는 기계식 스위치레버를 장착하고 있다. 그러나 기계적인 열화나 환경적인 요인에 의해 기계식 스위치레버의 특성이 점점 변화되어 마침내 잘못된 접점신호를 발생하게 된다. 그러므로 아들 문제 해결을 위해 기계식 스위지 대선 전자식 스위치를 검출기 안내관 밖에 배치하였고, 공진효과를 이용하여 점점신호를 발생하는 회로개선과 소음 및 전기적 방해를 방지하기 위한 콘데서를 전자회로 전원 입력측에 설치하였다. 이러한 개선을 완료한 후, 여러 조건하에서 이 향상된 스위치 제어회로를 반복적으로 시험하였는데, 결국 이를 통해 원하는 접점신호를 얻게되었을 뿐 아니라 발전소 정상운전 중에 관련시스템의 주기시험을 통해서도 검출기 접점 오동작 신호가 발생되지 않음울 확인할 수 있게 되었다.