PGSFR 가동중검사기술 개발

김회웅,주영상,이영규,박상진,구경회,김종범,김성균,Kim, Hoe Woong,Joo, Young Sang,Lee, Young Kyu,Park, Sang Jin,Koo, Gyeong Hoi,Kim, Jong Bum,Kim, Sung Kyun 한국압력기기공학회 2016 한국압력기기공학회 논문집 Vol.12 No.1

Since the sodium-cooled fast reactor is operated in a hostile environment due to the use of liquid sodium as its coolant, advanced techniques for in-service inspection are required to periodically verify the integrity of the reactor. This paper presents the development of in-service inspection techniques for Proto-type Generation IV Sodium-cooled Fast Reactor. First, the 10 m long plate-type ultrasonic waveguide sensor has been developed for in-service inspection of reactor internals, and its feasibility was verified through several under-water and under-sodium experiments. Second, the combined inspection system for in-service inspection of ferromagnetic steam generator tubes has been developed. The remote field eddy current testing and magnetic flux leakage testing can be conducted simultaneously by using the developed inspection system, and the detectability was demonstrated through several damage detection experiments. Finally, the electro-magnetic acoustic transducer which can withstand high temperature and be installable in the remote operated vehicle has been developed for in-service inspection of the reactor vessel, and its detectability was investigated through damage detection experiments.

배관에서의 특정 비틀림 초음파 모드 송수신을 위한 합성 위상 조절 기법

김회웅(Kim, Hoe Woong),권영의(Kwon, Young Eui),주영상(Joo, Young Sang),김종범(Kim, Jong Bum),김윤영(Kim, Yoon Young) 한국소음진동공학회 2013 한국소음진동공학회 논문집 Vol.23 No.3

This study newly presents a synthetic phase tuning technique to suppress the unwanted torsional mode while enhancing the desired torsional mode in a pipe. Specifically, we aim at the enhancement of the first torsional mode and the suppression of the undesired, second torsional mode. Earlier efforts were to enhance the desired wave mode only in the hope that the enhancement results in the suppression of the unwanted wave mode. Unlike these efforts, the suggested technique makes the complete cancellation of the unwanted wave mode but it is shown to enhance the desired first mode for torsional wave problems. In the present study, the synthetic phase tuning is developed for the cancellation of the unwanted wave mode, meaning that the number of necessary experimental equipments is reduced. Simulation and experiment were carried out to check the effectiveness of the proposed method. As an application of the suggested technique, we investigated the reflection and mode conversion characteristics of the first torsional mode according to the step thickness variation in a stepped pipe.

소듐냉각고속로 원자로용기 가동중검사를 위한 고온 전자기음향 트랜스듀서 개발

김회웅(Hoe-Woong Kim),박상진(Sang-Jin Park),손진관(Jin-Gwan Son),주영상(Young-Sang Joo),김성균(Sung-Kyun Kim),김종범(Jong-Bum Kim) 한국비파괴검사학회 2018 한국비파괴검사학회지 Vol.38 No.4

액체 금속인 소듐을 냉각재로 사용하는 제 4세대 원자로인 소듐냉각고속로의 원자로용기는 가동중 검사 기간에도 소듐의 고화를 방지하기 위해 200°C 정도의 고온 상태로 유지되어야 하고, 소듐-물 반응을 배제하기 위해 검사 시 액체 접촉 매질의 사용이 제한되어 있다. 또한, 원자로용기를 둘러싸고 있는 격납용기와의 간격이 협소하여 직접적인 접근이 어렵기 때문에 원격제어장비를 사용하여 검사를 수행하여야 한다. 이와 같은 가혹한 조건 하에서 원자로용기의 가동중검사를 수행하기 위해 본 연구에서는 원격제어장비에 탑재가 가능한 고온 전자기음향 트랜스듀서를 개발하였다. 먼저, 개발된 고온 전자기음향 트랜스듀서의 방사패턴과 리프트 오프에 따른 신호대잡음비 변화를 측정하여 개발된 트랜스듀서의 특성을 분석하였고, 내부 결함이 모사된 원자로용기 시편에 대한 결함 탐지능 측정시험과 내열성 시험 및 내구성 시험을 수행하여 고온 환경에서의 적용 가능성을 평가하였다. The reactor vessel in a sodium-cooled fast reactor, a generation-IV reactor, is in a high-temperature condition (approximately 200°C) even during the in-service inspection period and the liquid couplant, which is necessary for contact ultrasonic examination, is not permitted to be applied for the inspection to prevent sodiumwater reaction. Moreover, the remotely operated vehicle should be employed for inspection in the narrow gap between the reactor vessel and the containment vessel. For the in-service inspection of the reactor vessel under such harsh conditions, a high-temperature electro-magnetic acoustic transducer installable in the remotely operated vehicle was developed in this study. First, the radiation pattern and the signal-to-noise ratio according to the lift-off variation were investigated to analyze the characteristics of the developed transducer. Furthermore, the detectability, heat resistance, and durability of the developed transducer were then evaluated to demonstrate its applicability.

Development of a Ranging Inspection Technique in a Sodium-cooled Fast Reactor Using a Plate-type Ultrasonic Waveguide Sensor

Hoe Woong Kim(김회웅),Sang Hwal Kim(김상활),Jae Won Han(한재원),Young Sang Joo(주영상),Chang Gyu Park(박창규),Jong Bum Kim(김종범) 한국소음진동공학회 2015 한국소음진동공학회 논문집 Vol.25 No.1

In a sodium-cooled fast reactor, which is a Generation-IV reactor, refueling is conducted by rotating, but not opening, the reactor head to prevent a reaction between the sodium, water and air. Therefore, an inspection technique that checks for the presence of any obstacles between the reactor core and the upper internal structure, which could disturb the rotation of the reactor head, is essential prior to the refueling of a sodium-cooled fast reactor. To this end, an ultrasound-based inspection technique should be employed because the opacity of the sodium prevents conventional optical inspection techniques from being applied to the monitoring of obstacles. In this study, a ranging inspection technique using a plate-type ultrasonic waveguide sensor was developed to monitor the presence of any obstacles between the reactor core and the upper internal structure in the opaque sodium. Because the waveguide sensor installs an ultrasonic transducer in a relatively cold region and transmits the ultrasonic waves into the hot radioactive liquid sodium through a long waveguide, it offers better reliability and is less susceptible to thermal or radiation damage. A 10 m horizontal beam waveguide sensor capable of radiating an ultrasonic wave horizontally was developed, and beam profile measurements and basic experiments were carried out to investigate the characteristics of the developed sensor. The beam width and propagation distance of the ultrasonic wave radiated from the sensor were assessed based on the experimental results. Finally, a feasibility test using cylindrical targets (corresponding to the shape of possible obstacles) was also conducted to evaluate the applicability of the developed ranging inspection technique to actual applications.

결함 배관 영상화를 위한 SH 파 분절형 패치 배열 자기변형 트랜스듀서 개발

김회웅(Hoe Woong Kim),권영의(Young Eui Kwon),조승현(Seung Hyun Cho),김윤영(Yoon Young Kim) 한국소음진동공학회 2009 한국소음진동공학회 학술대회논문집 Vol.2009 No.11

자기변형 트랜스듀서에 의한 고주파대역 비틀림 초음파 발생에서의 이슈

김회웅(Hoe Woong Kim),조승현(Seung Hyun Cho),김윤영(Yoon Young Kim) 한국소음진동공학회 2009 한국소음진동공학회 학술대회논문집 Vol.2009 No.4

배관의 검사를 위한 자기변형 패치 트랜스듀서 기반의 위상배열 시스템

김회웅(Hoe Woong Kim),이주경(Joo Kyung Lee),김윤영(Yoon Young Kim) 한국소음진동공학회 2011 한국소음진동공학회 학술대회논문집 Vol.2011 No.10

보육행정서비스에 대한 보육시설장의 인식조사

김영태(Kim Young-Tae),김회웅(Kim Hoe-Woong) 한국열린유아교육학회 2010 열린유아교육연구 Vol.15 No.1

저출산의 기조와 여성의 사회진출로 인해 정부에서는 각종 보육정책을 쏟아내고 있다. 이들 보육정책이 효과적으로 서비스 대상자에게 전달되기 위해서는 보육행정전달체계를 거쳐야 한다. 그럼으로 본 연구에서는 이들 보육행정서비스의 수혜자이며 아동에 대한 최종 공급자인 보육시설의 시설장의 인식을 토대로 문제점을 발견하고 이에 대한 개선방안을 찾는데 그 목적을 두고 있다. 연구로부터 얻은 결과는 다음과 같다. 첫째, 보육행정서비스에 대한 인식은 국공립보육시설의 시설장들의 인식이 좋은 반면에 민간보육시설의 시설장들의 인식은 상대적으로 좋지 않았다. 둘째, 행정지원에 있어서는 공무원의 전문성 부족으로 지도감독 시 문제를 보이고 있었다. 셋째, 보육시설의 지역사회와의 연계를 위한 지원에 대하여는 세부사항의 혼란을 가지고 있었다. 넷째, 공무원의 시설방문은 시설에 부담으로 작용하고 있었으며, 특히 가정보육시설에서는 낮은 만족수준을 보여주었다. A trend of low birth rate and increase of women who enter into the labor market make various types of nursery policy created as the national priority welfare program. For these policies’ success, it needs to have effective delivery system for the recipient to receive good service. This study attempted to find ways to improve the of administration delivery system for nursery from problems based on the recognition of principals at day care centers through survey. From the analysis of the survey, it obtained the following result. First, principal’s recognition of public day care centers about administration delivery system is better than that of private day care centers. It means that principals of private day care centers have negative consciousness on the various types of administration problems. Second, civil servants who is responsible for administration of nursery delivery system lack expert knowledge to supervise principals. Therefore, it needs professional inspectors for the supervision like school inspectors of kindergarten. Third, according to the guide book for day care center, it recommends to organize parental meeting. However, it does not have detailed rules for concrete performance. Therefore, it needs to make detailed rules to prevent confusion in the field. Fourth, private day care centers with a capacity limit under 20 have serious problems when a civil servant who is responsible for day care centers visiting the center. The centers have only 2-4 workers for the children/ infants. Therefore, they experience lack of teachers when a principal or teachers work with the civil servant.

서울시를 중심으로 한 질 관리 유형별 보육시설 간 보육사업 지표 비교연구

김영태(Kim Young-Tae),김회웅(Kim Hoe-Woong) 한국열린유아교육학회 2010 열린유아교육연구 Vol.15 No.2

영유아 보육법이 1991년에 제정된 이후 보육 사업은 비약적인 발전을 이루었으나, 많은 부모들은 자녀들을 믿고 맡길 만한 보육시설이 주위에 많지 않다고 하고 있다. 이에 정부에서는 평가인증제도를 시행하였고 서울시에서도 지방정부수준에서 서울형 어린이집이라는 이름으로 보육시설 질 개선사업을 시작하였다. 본 연구에서는 중앙정부와 지방정부(서울시 정부)수준에서의 보육서비스 질 개선 사업이 어느정도 민간보육시설의 서비스를 개선시켰는지에 대한 연구를 실시하였다. 이를 위해 영유아보육법 기준에 맞춘 시설과 평가인증통과시설, 서울형 어린이집에 대하여 여섯 개 영역에 걸쳐 교차분석 및 일원배치분산분석을 사용하여 비교를 실시하였다. 비교 결과 모든 영역에서 서울형 어린이집이 기준시설이나 평가인증시설에 비해 높은 수준을 보여주었다. After the enactment of Toddlers and Infants nurture law in 1991, child care services for toddlers and infants have rapidly progressed within a number of centers. However, in the case of quality, many parents are worried because of the low qualitative level of services at child care center. So, the central government attempted new policies involving evaluation and accreditation system for better quality service at child care center in 2005. In April of 2009 Seoul metropolitan government started a revolutionary qualitative improvement policy for child care center which was called Seoul-style child care center. This study tried to show a comparison between six areas for three qualitative improvement program including standard, accreditation and Seoul style child care center. The following result shows the summary of the study. First, operation management improved various areas including record and custody of document related to operation at Seoul-style child care center. Second, on the side of human resource, it included improvement in various aspects such as education opportunity, reward, and career management for workers and others at Seoul style child care center. Third, educational management increased the participation of infant and children during class at Seoul-style child care center. Forth, environment at child care center, it is well lightened and division based education program at Seoul-style child care center. Fifth, health, nutrition and safety, to attain a good health management, clean environment and food service for infant and children at Seoul style child care center. Sixth, Seoul-style child care center provides better delivery of information on services and about parents' son or daughter and activity and program about the function of parents. To sum up, Seoul-style child care center showed higher qualitative level rather than both standard and care service center with accreditation.

PGSFR 제어봉집합체 낙하성능시험

이영규,김회웅,이재한,구경회,김종범,김성균,Lee, Young Kyu,Kim, Hoe Woong,Lee, Jae Han,Koo, Gyeong Hoi,Kim, Jong Bum,Kim, Sung Kyun 한국압력기기공학회 2016 한국압력기기공학회 논문집 Vol.12 No.1

The Control Rod Assembly (CRA) controls the reactor power by adjusting its position in the reactor core during normal operation and should be quickly inserted into the reactor core by free drop under scram condition to shut down chain reactions. Therefore, the drop time of the CRA is one of important factors for the safety of the nuclear reactor and must be experimentally verified. This study presents the drop performance test of the CRA which has been conceptually designed for the Proto-type Generation IV Sodium-cooled Fast Reactor. During the test, the CRA was free dropped from a height of 1 m under different flow rate conditions and its drop time was measured. The results showed that the drop time of the CRA increased as the flow rate increased; the average drop times of the CRA were approximately 1.527 seconds, 1.599 seconds and 1.676 seconds at 0%, 100% and 200% of design flow rates, respectively.