Title: Failure possibilities for nuclear safety assessment by fault tree analysis

Authors: Julwan Hendry Purba, Jie Lu, Guangquan Zhang, Da Ruan

Addresses: Centre for Quantum Computation & Intelligent Systems (QCIS), School of Software, Faculty of Engineering and Information Technology, University of Technology, Sydney (UTS), PO Box 123, Broadway, NSW 2007, Australia. ' Centre for Quantum Computation & Intelligent Systems (QCIS), School of Software, Faculty of Engineering and Information Technology, University of Technology, Sydney (UTS), PO Box 123, Broadway, NSW 2007, Australia. ' Centre for Quantum Computation & Intelligent Systems (QCIS), School of Software, Faculty of Engineering and Information Technology, University of Technology, Sydney (UTS), PO Box 123, Broadway, NSW 2007, Australia. ' Belgian Nuclear Research Centre (SCK-CEN), Boeretang 200, 2400 Mol, Belgium; Department of Applied Mathematics and Computer Science, Ghent University, Krijgslaan 281 (S9), 9000 Gent, Belgium

Abstract: Fault tree analysis (FTA) is a deductive tool to assess the safety of nuclear power plants. This analysis can only be implemented if all basic events in the tree have their corresponding failure rates. Therefore, safety analysts have to provide those failure rates well in advance. However, it is often difficult to obtain those failure rates due to insufficient data, changing environment or new components. This paper proposes a failure possibility based FTA approach to overcome the limitation of the conventional FTA for nuclear safety assessment. It utilises the concept of failure possibilities to evaluate basic event failure without historical data, fuzzy numbers to map component failure possibilities into mathematical form and defuzzification algorithms to convert fuzzy numbers into component failure rates. A case study on evaluating a typical high pressure core spray system of a boiling water reactor illustrates the applicability of the proposed approach.

Keywords: failure possibilities; nuclear safety assessment; fault tree analysis; FTA; expert justification; fuzzy numbers; nuclear energy; nuclear power plants; NPP safety; component failure rates; failure possibility; high pressure spraying; core spray systems; boiling water reactors; BWRs.

DOI: 10.1504/IJNKM.2011.040940

International Journal of Nuclear Knowledge Management, 2011 Vol.5 No.2, pp.162 - 177

Published online: 26 Jun 2011 *

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