Nuclear Engineering and Technology

  • 제40권3호
  • /
  • Pages.239-250
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  • 2008
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  • 1738-5733(pISSN)
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  • 2234-358X(eISSN)
한국원자력학회 (Korean Nuclear Society)
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SURGE LINE STRESS DUE TO THERMAL STRATIFICATION

  • 발행 : 2008.04.30
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초록

If there is a water flow with a range of temperature inside a pipe, the wanner water tends to float on top of the cooler water because it is lighter, resulting in the upper portion of the pipe being hotter than the lower portion. Under these conditions, such thermal stratification can play an important role in the aging of nuclear power plant piping because of the stress caused by the temperature difference and the cyclic temperature changes. This stress can limit the lifetime of the piping, even leading to penetrating cracks. Investigated in this study is the effect of thermal stratification on the structural integrity of the pressurizer surge line, which is reported to be one of the pipes most severely affected. Finite element models of the surge line are developed using several element types available in a general purpose structural analysis program and stress analyses are performed to determine the response characteristics for the various types of top-to-bottom temperature differentials due to thermal stratification. Fatigue analyses are also performed and an allowable environmental correction factor is suggested.

키워드

참고문헌

  1. USNRC, Thermal Stresses in Piping Connected to Reactor Coolant Systems, Bulletin No. 88-08, U.S. Nuclear Regulatory Commission, Washington, DC (1988)
  2. USNRC, Pressurizer Surge Line Thermal Stratification, Bulletin No. 88-11, U.S. Nuclear Regulatory Commission, Washington, DC (1988)
  3. NEA, Thermal Cycling in LWR Components in OECDNEA Member Countries, NEA/CSNI/R(2005)8, NEA CSNI, CSNI Integrity and Ageing Working Group, Organization for Economic Co-operation and Development (2005)
  4. ANSYS, ANSYS Structural Analysis Guide, ANSYS, Inc., Houston (2007)
  5. Grimes, R.G., Lewis, J.G., and Simon, H.D., 'A Shifted Block Lanczos Algorithm for Solving Sparse Symmetric Generalized Eigenproblems,' SIAM Journal on Matrix Analysis and Applications, Vol.15, No.1, pp.228-272 (1994) https://doi.org/10.1137/S0895479888151111
  6. Jhung, M.J., Kang, D.G., and Jo, J.C., 'Coupled Thermal Hydraulic and Stress Analysis of Pipe with Two Bends,' Transactions of the Korean Society of Pressure Vessels and Piping, Vol.3, No.2, pp.65-70 (2007)
  7. ASME, ASME Boiler and Pressure Vessel Code, Section III, Appendix I Design Stress Intensity Values, Allowable Stresses, Material Properties, and Design Fatigue Curves, The American Society of Mechanical Engineers (2004)
  8. USNRC, 'Guidelines for evaluating fatigue analysis incorporating the life reduction of metal components due to the effects of the light-water reactor environment for new reactors,' Regulatory Guide 1.207, U.S. Nuclear Regulatory Commission, Washington, DC (2007)
  9. USNRC, 'Effect of LWR Coolant Environments on Fatigue Life of Reactor Materials,' NUREG/CR-6909, U.S. Nuclear Regulatory Commission, Washington, DC (2007)