Application of PAA in EPR Nuclear Power Units

doi:10.23940/ijpe.19.01.p2.1322

Abstract

Abstract:

Forced unavailability of units not only influences economic indicators of nuclear power units like availability, but also seriously threatens the safe operation of units. It is significantly important for the safety and economy of nuclear power units to reduce forced shutdown times and shorten forced shutdown times of nuclear power units. In this paper, on the basis of European Pressurized Water Reactor (EPR) units for the third generation nuclear power, the application of VVP and ARE systems in EPR units is studied based on the Probabilistic Availability Assessment (PAA) method. Critical failure modes that influence forced unavailability of units are determined by Failure Mode and Effect Analysis (FMEA). Based on this, the unplanned shutdown time that influences unit availability is calculated, whether the unplanned unavailability of EPR units can meet the requirements is evaluated, critical weaknesses are identified, and methods of optimization are put forward. The results are a good reference for design and research, system configuration, and equipment selection of newly-built nuclear power units, and they also provide referable opinions and suggestions for improving the reliability of existing nuclear power units.

Key words: EPR, forced unavailability, PAA

Wen Chen, Zhiwu Wang, Chen Qing, Shijun Chen, Jiefei Chen, Yu Chen, Hong Jiang, and Tao Zhang. Application of PAA in EPR Nuclear Power Units [J]. Int J Performability Eng, 2019, 15(1): 13-22.

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Figures/Tables 9

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References 15

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Category	Index description	Index value
Parameters of unplanned scram	Unplanned automated scram frequency	< 1 time/7000 critical hours
	Duration of forced outage	≤ 5 days/year (1.4%)
	Overhaul deferral due to major equipment maintenance or replacement	≤ 150 days/20years

Power plant system	Unavailable time (empirical feedback)	Allocated unavailable time (1.4%)	Historical experience/unavailability of distribution
VVP	0.99	1.00	0.99
ARE	2.0	2.00	1.00

Component ID	Component type	Failure mode
Main steam pipeline	Main steamisolation valve MSIV	Fail to close
Main steam pipeline	Main steam isolation valve MSIV	Closed by mistake

Component ID	Component type	Failure mode
Main feed-water pipeline	Main feed-water regulating valve	Fail to regulate
	Main feed-water isolation valve	Refuse to close
	Main feed-water isolation valve	Close by mistake

Component code	Failure mode	Failure rate
Main steam pipeline	Refuse to close	3.1×10-4
Main steam pipeline	Close by mistake	1.9×10-6
Main feed-water pipeline	Fail to regulate	2.8E-06
	Refuse to close	3.0E-04
	Close by mistake	3.08E-07