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Applicability Evaluation of Methodology for Evaluating High Cycle Thermal Fatigue of a Mixing Tee in Nuclear Power Plants

원전 혼합배관 고주기 열피로 평가방법론의 적용성 평가

  • 김선혜 (성균관대학교 기계공학부) ;
  • 성희동 (성균관대학교 기계공학부) ;
  • 최재붕 (성균관대학교 기계공학부) ;
  • 허남수 (서울과학기술대학교 기계설계자동차공학부) ;
  • 박정순 (한국원자력안전기술원) ;
  • 최영환 (한국원자력안전기술원)
  • Received : 2011.11.12
  • Accepted : 2011.11.22
  • Published : 2011.12.01

Abstract

Turbulent mixing of hot and cold coolants is one of the possible causes of high cycle thermal fatigue in piping systems of nuclear power plants. A typical situation for such mixing appears in turbulent flow through a T-junction. Since the high cycle thermal fatigue caused by thermal striping was not considered in the piping fatigue design in several nuclear power plants, it is very important to evaluate the effect of thermal striping on the integrity of mixing tees. In the present work, before conducting detailed evaluation, three thermal striping evaluation methodology suggested by EPRI, JSME and NESC are analyzed. Then, a by-pass pipe connected to the shutdown cooling system heat exchanger is investigated by using these evaluation methodology. Consequently, the resulting thermal stresses and the fatigue life of the mixing tee are reviewed and compared to each other. Futhermore, the limitation of each methodology are also presented in this paper.

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