Effect of test-caused degradation on the unavailability of standby safety components

S. Parsaei; A. Pirouzmand; M.R. Nematollahi; A. Ahmadi; K. Hadad

Nuclear Engineering and Technology (Feb 2024)

Effect of test-caused degradation on the unavailability of standby safety components

S. Parsaei,
A. Pirouzmand,
M.R. Nematollahi,
A. Ahmadi,
K. Hadad

Affiliations

S. Parsaei: Department of Nuclear Engineering, School of Mechanical Engineering, Shiraz University, Shiraz, Iran
A. Pirouzmand: Department of Nuclear Engineering, School of Mechanical Engineering, Shiraz University, Shiraz, Iran; Safety Research Center, School of Mechanical Engineering, Shiraz University, Shiraz, Iran; Corresponding author. Department of Nuclear Engineering, School of Mechanical Engineering, Shiraz University, Shiraz, Iran.
M.R. Nematollahi: Department of Nuclear Engineering, School of Mechanical Engineering, Shiraz University, Shiraz, Iran; Safety Research Center, School of Mechanical Engineering, Shiraz University, Shiraz, Iran
A. Ahmadi: Division of Operation and Maintenance, Luleå University of Technology, Luleå, Sweden
K. Hadad: Department of Nuclear Engineering, School of Mechanical Engineering, Shiraz University, Shiraz, Iran; Safety Research Center, School of Mechanical Engineering, Shiraz University, Shiraz, Iran

Journal volume & issue: Vol. 56, no. 2
pp. 526 – 535

Abstract

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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.

Published in Nuclear Engineering and Technology

ISSN: 1738-5733 (Print)
Publisher: Elsevier
Country of publisher: Korea, Republic of
LCC subjects: Technology: Electrical engineering. Electronics. Nuclear engineering: Nuclear engineering. Atomic power
Website: http://www.journals.elsevier.com/nuclear-engineering-and-technology

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