Journal of Energy Engineering (에너지공학)

The Korean Society for Energy (한국에너지학회)
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Effects of Expanding Methods on Residual Stress of Expansion Transition Area in Steam Generator Tube of Nuclear Power Plants

원전 증기발생기 전열관 확관법이 확관부위 잔류응력에 미치는 영향

  • 김용규 (홍익대학교 금속공학과) ;
  • 송명호 (한국원자력안전기술원 연구정책단)
  • Received : 2012.09.10
  • Accepted : 2012.12.02
  • Published : 2012.12.31
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Abstract

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.

원전의 증기발생기 전열관은 압력경계 부위로 결함발생으로 인한 누설 시 방사능물질을 함유한 1차 계통의 냉각수가 2차 계통으로 새어나와 발전소 및 대기를 오염시키게 된다. 근래에 전열관의 균열결함은 대개 응력 부식균열이며 전열관의 확관부위, 슬러지 침적부위 그리고 U-bend 등에서 발생한다. 확관부위 및 U-bend 등에서의 균열발생인자 중 가장 영향을 미치는 인자는 잔류응력이다. 폭발확관법이 적용된 한국표준형원전(OPR-1000)의 운전경험에 따르면, 증기발생기 전열관 확관부위에서 가동 초기부터 응력부식균열이 발생해 왔으며, 특히 원주방향 균열이 대량 발생하고 있다. 따라서 본 연구에서는 확관방법에 따른 잔류응력의 분포 및 상태를 비교하였으며, 특정 방향이 우세한 원인을 살펴보았다.

Keywords

Acknowledgement

Supported by : 홍익대학교

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Cited by

  1. A Study on the Resistance of Stress Corrosion Cracking due to Expansion Methods for Steam Generator Tubes in Nuclear Power Plants vol.23, pp.2, 2014, https://doi.org/10.5855/ENERGY.2014.23.2.149
  2. Stress Analysis of Expansion Transition Area in Steam Generator Tube of Optimized Power Reactor-1000 vol.22, pp.2, 2013, https://doi.org/10.5855/ENERGY.2013.22.2.148