• Proceedings of the KIEE Conference
• /
• 1998.07g
• /
• pp.2433-2435
• /
• 1998

원자력발전소의 증기발생기는 기능상으로도 중요한 역할을 하지만 증기발생기 내의 전열관 손상이나 누설은 바로 방사능 누출의 원인이 되므로 원자력 발전소의 안전성 측면에서 보면 매우 중요한 설비이다. 따라서, 증기발생기 전열관은 정기보수시 마다 전열관 각각에 대해 비파괴검사의 일종인 와전류검사(Eddy Current Testing, ECT)를 통해 건전성을 평가하고 있다. 현재는 신호를 취득하고 평가하는 업무가 별개의 기관에서 수행하고 있으며 이를 위해 현장에 관련 인력과 장비가 이동되어야 한다. 그러나, 취득한 신호를 평가자가 on-line으로 받을 수 있고 그 결과를 이용하여 즉시 피드백이 가능하다면 평가기관의 인력은 현장에 있지 않더라도 평가가 가능하다. 그러므로, 원격 평가 환경을 구축한다는 것은 평가자가 굳이 현장에 가지 않더라도 지역에 상관없이 LAN을 활용하여 전국 어디서든 평가가 가능하도록 하고자 함에 있다.

• Proceedings of the SAREK Conference
• /
• 2009.06a
• /
• pp.857-862
• /
• 2009

In this study, the numerical study has carried out to analyze the leakage in a steam turbine labyrinth seal. We modified tooth shape of the labyrinth seal and finds out difference of leakage in this study. Original model is straight labyrinth seal and its modified model is slant labyrinth seal. The numerical analyses are implemented on two models. The numerical results show that each leakage of tooth shape are found 0.4781 kg/s and 0.4485 kg/s, respectively. Slant labyrinth seal seals in a steam better than straight labyrinth seal. Since, actual clearance of the stream function in the slant model is smaller than the straight model.

• Proceedings of the Korean Nuclear Society Conference
• /
• 1995.10a
• /
• pp.211-216
• /
• 1995

1994년 11월에 나타난 고리 1호기 증기발생기의 전열관 누설에 대한 원인을 조사하기 위하여 인출 전열관의 파손 분석과 슬러지 분석 및 pH 분석 등을 수행하였다. 손상원인은 국부적인 염기도 상승과 부식전위 상승에 따른 2차측 응력부식균열(ODSCC)로 밝혀졌다. 전열관 표면과 접한 관판 상부의 퇴적슬러지 끝단에 형성된 틈새에서 나타나는 비등현상으로 $Na^{+}$ 등의 양이온이 농축하게 되며, Cl$^{-}$ 등의 음이온 증발로 인하여 국부적으로 염기도의 상승현상이 야기되었다. 또한 재 가동시 전열관 표면에 침착된 잔류 구리와 용존산소의 결합으로 부식전위가 상승되었다. 이와 같은 ODSCC 발생환경은 1990년이래 지속적으로 형성된 것으로 판단된다.

• Proceedings of the Korean Society for Noise and Vibration Engineering Conference
• /
• 1992.10a
• /
• pp.81-86
• /
• 1992

원자력발전소 1차 계통 내의 건전성 감시를 위한 설비로는 음향누설 감시계 통(Acoustic Leak Monitoring System: ALMS), 금속파편 감시계통(Loose Parts Monitoring System: LPMS) 및 원자로내부구조물 진동감시계통 (Internals Vibration Monitoring System: IVMS)등이 있다. 현재, 국내의 여 러 원전에는 이들중 일부 계통들이 선택적으로 설치되어 운전중이며, 영광 3,4호기에서는 국내 최초로 이들 3개의 계통을 종합한 핵증기공급계통 건전 성감시계통(Nuclear Steam Supply System Integrity Monitoring System: NIMS)을 설계하였다. 특히, 영광 3,4호기 NIMS에서는 각 계통에 의해 감지 된 1차 계통 내의 이상상태를 하나의 분석컴퓨터(Analysis Computer)를 사 용하여 해석하는 종합결함 탐지해석 기법을 도입하였다.

• Korean Chemical Engineering Research
• /
• v.55 no.2
• /
• pp.170-179
• /
• 2017

We investigated design requirements of feed water drain and hydrogen vent systems for the sodium-water reaction pressure relief system (SWRPRS) of the prototype generation IV sodium cooled fast reactor (PGSFR). We evaluated the areas of the gas vent pipe of the water dump tank and the length of the water drain pipe of the steam generator to rapid drain of the water steam inside the steam generator for the normal and refueling operations, respectively. We also calculated the diameter of the gas vent pipe of the sodium dump tank which met its design pressure.

• Journal of the Korean Society for Nondestructive Testing
• /
• v.33 no.5
• /
• pp.465-471
• /
• 2013

A steam generator in nuclear power plant is a heatexchager which is used to convert water into steam from heat produced in a nuclear reactor core, and the steam produced in steam generator is delivered to the turbine to generate electricity. Because of damage to steam generator tubing may impair its ability to adequately perform required safety functions in terms of both structural integrity and leakage integrity, eddy current testing is periodically performed to evaluate the integrity of tubes in steam generator. This assessment is normally performed during a reactor refueling outage. Currently, the eddy current testing for steam generator of nuclear power plant in Korea is performed in accordance with KEPIC & ASME Code requirements, the eddy current testing system is consists of remote data acquisition unit and data analysis program to evaluate the acquired data. The KEPIC & ASME Code require that the electrical properties of remote data acquisition unit, such as total harmonic distortion, input & output impedance, amplifier linearity & stability, phase linearity, bandwidth & demodulation filter response, analog-to-digital conversion, and channel crosstalk shall be measured in accordance with the KEPIC & ASME Code requirements. In this paper, the measurement requirements of electrical properties for eddy current testing instrument described in KEPIC & ASME Code are presented, and the measurement results of newly developed eddy current testing instrument by KHNP(Korea Hydro & Nuclear Power Co., LTD) are presented.

• Journal of Energy Engineering
• /
• v.21 no.4
• /
• pp.362-372
• /
• 2012

The steam generator tubes of nuclear power plants are pressure boundaries, and if tubes are leaked, the coolant with the radioactive materials was flowed out from the primary system to the secondary system and polluted the plant and the air. Recently most crack defects of tubes are stress corrosion cracks and these defects are located in expansion transition area, sludge pile-up region, and U-bend area. The most effective one of crack initiation factors in expansion transition area and U-bend area is the residual stress. According to the experiences of Korea standard nuclear plants(Optimized Power Reactor-1000), they had the stress corrosion cracks at the tube expansion transition area in early operating stage and especially lots of circumferential cracks were occurred. Therefore in this study, the distributions and conditions of residual stresses by tube expansion methods were compared and the dominant reason of a specific direction was examined.

• Transactions of the Korean Society of Mechanical Engineers B
• /
• v.35 no.10
• /
• pp.1097-1103
• /
• 2011

Liquid droplet impingement erosion (LDIE) is caused by the impact of high-velocity droplets entrained in steam or air on metal. The degradation caused by the LDIE has been experienced in steam turbine internals and high-velocity airplane components (particularly canopies). Recently, LDIE has also been observed in the pipelines of nuclear plants. LDIE among the pipelines occurs when two-phase steam experiences a high pressure drop (e.g., across an orifice in a line to the condenser). In 2011, a nuclear power plant in Korea experienced a steam leak caused by LDIE in a pipe through which a two-phase fluid was flowing. This paper describes a study on the design change of a pipe affected by LDIE in order to mitigate the damage. The design change has been reviewed in terms of fluid dynamics by using the FLUENT code.

• Journal of the Korean Society for Precision Engineering
• /
• v.30 no.7
• /
• pp.741-748
• /
• 2013

A conventional packing ring was designed with a large clearance to prevent damage due to the vibration of the rotor, which can lead to an increase in steam leakage. In this study, a flexible packing ring using winding springs was developed to prevent damage to the rotor teeth by minimizing vibration, while maintaining a smaller clearance than that of conventional rotor designs. Theoretical analysis and finite element analysis (FEA) were used to design the winding spring to satisfy the specified allowable stress limit and minimum load requirements. The shape of the winding spring was designed by applying curves to the center and end parts of a flat spring. Computational fluid dynamics (CFD) analysis was used to predict the leakage of the flexible packing ring. Flow rate measurement tests were performed to verify the leakage reduction efficiency and the reliability of the CFD analysis.

• Plant Journal
• /
• v.5 no.2
• /
• pp.56-61
• /
• 2009

In this study, the numerical study has been carried out to analyze the leakage in a steam turbine labyrinth seal. We modified tooth shape of the labyrinth seal and find out the difference of leakage in this study. Original model is straight labyrinth seal and its modified model is slanted labyrinth seal. The numerical analyses are implemented on two models. The numerical results show that each leakage of tooth shape are found to be 0.4781 kg/s and 0.4485 kg/s, respectively. The slanted labyrinth seal confines in a steam better than straight labyrinth seal. Since actual clearance of the stream function in the slant model is smaller than that of the straight model.