Nuclear Engineering and Technology

Korean Nuclear Society (한국원자력학회)
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Effect of test-caused degradation on the unavailability of standby safety components

  • S. Parsaei (Department of Nuclear Engineering, School of Mechanical Engineering, Shiraz University) ;
  • A. Pirouzmand (Department of Nuclear Engineering, School of Mechanical Engineering, Shiraz University) ;
  • M.R. Nematollahi (Department of Nuclear Engineering, School of Mechanical Engineering, Shiraz University) ;
  • A. Ahmadi (Division of Operation and Maintenance, Lulea University of Technology) ;
  • K. Hadad (Department of Nuclear Engineering, School of Mechanical Engineering, Shiraz University)
  • Received : 2023.03.27
  • Accepted : 2023.10.21
  • Published : 2024.02.25
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Abstract

This paper proposes a safety-critical standby component unavailability model that contains aging effects caused by the elapsed time from installation, component degradation due to surveillance tests, and imperfect maintenance actions. An application of the model to a Motor-Operated Valve and a Motor-Driven Pump involved in the HPIS of a VVER/1000-V446 nuclear power plant is demonstrated and compared with other existing models at component and system levels. In addition, the effects of different unavailability models are reflected in the NPP's risk criterion, i.e., core damage frequency, over five maintenance periods. The results show that, compared with other models that do not simultaneously consider the full effects of degradation and maintenance impacts, the proposed model realistically evaluates the unavailabilities of the safety-related components and the involved systems as a plant age function. Therefore, it can effectively reflect the age-dependent CDF impact of a given testing and maintenance policy in a specified time horizon.

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References

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