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

The Korean Society of Mechanical Engineers (대한기계학회)
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Derivation of Elastic Stress Concentration Factor Equations for Debris Fretting Flaws in Pressure Tubes of Pressurized Heavy Water Reactors

가압중수로 압력관 이물질 프레팅 결함의 탄성 응력집중계수 수식 도출

  • Received : 2013.09.14
  • Accepted : 2013.12.03
  • Published : 2014.02.01
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Abstract

If volumetric flaws such as bearing pad fretting flaws and debris fretting flaws are detected in the pressure tubes of pressurized heavy water reactors during in-service inspection, the initiation of fatigue cracks and delayed hydrogen cracking from the detected volumetric flaws shall be assessed by using elastic stress concentration factors in accordance with CSA N285.8-05. The CSA N285.8-05 presents only an approximate formula based on linear elastic fracture mechanics for the debris fretting flaw. In this study, an engineering formula considering the geometric characteristics of the debris fretting flaw in detail was derived using two-dimensional finite element analysis and Kinectrics, Inc.'s engineering procedure with slight modifications. Comparing the application results obtained using the derived formula with the three-dimensional finite element analysis results, it is found that the results obtained using the derived formula agree well with the results of the finite element analysis.

가동중검사 동안 가압중수로 압력관에서 탐지된 베어링 패드 프레팅 결함, 이물질 프레팅 결함 등 체적결함에 대해서는 CSA N285.8-05 에 따라 탄성 응력집중계수 수식을 이용하여 피로균열 및 수소지연균열이 개시되는 것을 평가하여야 한다. CSA N285.8-05 에는 이물질 프레팅 결함에 대해서는 선형파괴역학 기반한 개략적인 수식만이 제시된다. 본 연구에서는 이러한 이물질 프레팅 결함에 대해 2 차원 유한요소 해석과 일부 수정된 Kinectrics 사의 공학적 절차를 통해 이물질 프레팅 결함의 기하학적 특성이 좀더 상세히 고려된 탄성 응력집중계수 수식을 도출하였다. 도출된 수식을 적용한 결과와 3 차원 유한요소 해석 결과를 비교한 결과, 도출된 수식은 유한요소 해석과 잘 일치하는 결과를 얻을 수 있음을 확인하였다.

Keywords

References

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