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Publication Citation: A Risk-Uncertainty Formula Accounting for Uncertainties of Failure Probability and Consequence in a Nuclear Powerplant

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Author(s): Jeffrey T. Fong; Stephen R. Gosselin; Pedro V. Marcal; James J. Filliben; Nathanael A. Heckert; Robert E. Chapman;
Title: A Risk-Uncertainty Formula Accounting for Uncertainties of Failure Probability and Consequence in a Nuclear Powerplant
Published: July 20, 2010
Abstract: This paper is a continuation of a recent ASME Conference paper entitled "Design of a Python-Based Plug-in for Bench-marking Probabilistic Fracture Mechanics Computer Codes with Failure Event Data" (PVP2009-77974). In that paper, which was co-authored by Fong, deWit, Marcal, Filliben, Heckert, and Gosselin, we designed a probability-uncertainty plug-in to automate the estimation of leakage probability with uncertainty bounds due to variability in a large number of factors. The estimation algorithm was based on a two-level full or fractional factorial design of experiments such that the total number of simulations will be small as compared to a Monte-Carlo method. This feature is attractive if the simulations were based on finite element analysis with a large number of nodes and elements. In this paper, we go one step further to derive a risk-uncertainty formula by computing separately the probability-uncertainty and the consequence-uncertainty of a given failure event, and then using the classical theory of error propagation to compute the risk-uncertainty within the domain of validity of that theory. The estimation of the consequence-uncertainty is accomplished by using a public-domain software package entitled "Cost-Effectiveness Tool for Capital Asset Protection, version 4.0, 2008" (http://www.bfrl.nist.gov/oae/ or NIST Report NISTIR-7524), and is more fully described in a companion paper entitled "An Economics-based Intelligence (EI) Tool for Pressure Vessels & Piping (PVP) Failure Consequence Estimation," (PVP2010-25226, Session MF-23.4 of this conference). A numerical example of an application of the risk-uncertainty formula using a 16-year historical database of probability and consequence of main steam and hot reheat piping systems is presented. Implication of this risk-uncertainty estimation tool to the design of a risk-informed in-service inspection program is discussed.
Proceedings: Proceedings of the ASME Pressure Vessels and Piping Conference
Pages: 24 pp.
Location: Bellevue, WA
Dates: July 18-22, 2010
Keywords: ASME B&PV Code; error propagation; failure consequence; failure probability; nuclear power plant; probabilistic risk assessment; risk uncertainty formula
Research Areas: Measurement Solutions, Software Testing Metrics, Modeling
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