Transactions of the Korean Society of Mechanical Engineers A (대한기계학회논문집A)

The Korean Society of Mechanical Engineers (대한기계학회)
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Leak-Before-Break (LBB) Assessment Method Considering Crack Nonlinearity Using Effective Elastic Modulus and Material Nonlinearity

유효탄성계수를 이용한 균열 비선형 및 재료 비선형을 고려한 파단전누설(LBB) 평가 방법

  • Kim, Maan-Won (Nuclear Engineering & Technology Institute, Korea Hydro & Nuclear Power Co., Ltd.) ;
  • Kim, Sung-Hwan (Nuclear Engineering & Technology Institute, Korea Hydro & Nuclear Power Co., Ltd.) ;
  • Lee, Eui-Jong (Nuclear Engineering & Technology Institute, Korea Hydro & Nuclear Power Co., Ltd.)
  • 김만원 (한국수력원자력(주) 원자력발전기술원) ;
  • 김성환 (한국수력원자력(주) 원자력발전기술원) ;
  • 이의종 (한국수력원자력(주) 원자력발전기술원)
  • Received : 2010.12.14
  • Accepted : 2011.03.15
  • Published : 2011.06.01
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Abstract

With the increase in the thermal power output of recently developed nuclear power plants, the applied forces and moments are increased in some piping systems, so that the leak-before-break (LBB) application criteria would not be satisfied in those pipes. In this paper, we present a method for obtaining the additive LBB margin in the pipes by considering the nonlinearity of the crack and material properties. Finite element analysis and the moment-rotation equation of beam theory were used to calculate the nonlinearity of the crack and material properties. Moreover crack stability analysis was performed using the method proposed in this study. The LBB margin was increased effectively through consideration of the nonlinearity of the crack and material properties in the pipe.

최근 열출력이 향상된 신규 원자력발전소의 개발이 증가하고 있으며 배관계에 가해지는 모멘트 및 하중의 크기도 증가하는 경향이므로 배관의 파단전누설(LBB) 적용조건 여유도가 작아질 수 있다. 본 논문에서는 이러한 배관에서 LBB 적용조건을 만족시키기 위한 추가적인 여유도 확보의 한 방법으로써 균열의 비선형과 재료물성치를 고려하는 방법을 제시하였다. 균열 및 재료의 비선형을 고려하기 위하여 유한요소해석과 보(beam) 이론을 병용하였다. 원자력 배관을 모델로 하여 본 논문에서 제안한 방법으로 LBB 균열안정성 해석을 수행하였으며, LBB 여유도가 낮은 위치에서 균열 및 재료 비선형을 고려함으로 써 추가적인 LBB 여유도를 확보할 수 있음을 확인하였다.

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References

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