An application of the explicit method for analysing intersystem dependencies in the evaluation of event trees

Oliveira, L.F.; Melo, Prı́amo A.; Lima, J. E.; Stal, Israel L.

doi:10.1016/0029-5493(85)90029-9

Cited by 3 publications

(2 citation statements)

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“…The BDD of a formula is a compact encoding of the truth table of this formula. It would be interesting to investigate, in this context, the role of the opposite approach to perform a PSA: the one of large event trees and small fault trees, known as event trees with boundary conditions (or explicit method) [32,35].…”

Section: Discussionmentioning

confidence: 99%

“…According to [37], it should be adequate to retain the minimal cut sets that contribute 90-99% to the point estimate CDF. However, a tighter control could be necessary to take into account smaller probability/frequency cut sets that might have substantially larger uncertainty factors compared with those that dominate the point estimate CDF [35].…”

Section: Discussionmentioning

confidence: 99%

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Risk-Based Allowed Outage Time and Surveillance Test Interval Extensions for Angra 1

Gibelli

Melo

Leite

2012

International Journal of Quality, Statistics, and Reliability

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In this work, Probabilistic Safety Assessment (PSA) is used to evaluate Allowed Outage Times (AOT) and Surveillance Test Intervals (STI) extensions for three Angra 1 nuclear power plant safety systems. The interest in such an analysis lies on the fact that PSA comprises a risk-based tool for safety evaluation and has been increasingly applied to support both the regulatory and the operational decision-making processes. Regarding Angra 1, among other applications, PSA is meant to be an additional method that can be used by the utility to justify Technical Specification relaxation to the Brazilian regulatory body. The risk measure used in this work is the Core Damage Frequency, obtained from the Angra 1 Level 1 PSA study. AOT and STI extensions are evaluated for the Safety Injection, Service Water and Auxiliary Feedwater Systems using the SAPHIRE code. In order to compensate for the risk increase caused by the extensions, compensatory measures as (1) test of redundant train prior to entering maintenance and (2) staggered test strategy are proposed. Results have shown that the proposed AOT extensions are acceptable for two of the systems with the implementation of compensatory measures whereas STI extensions are acceptable for all three systems.

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Section: Discussionmentioning

confidence: 99%

Section: Discussionmentioning

confidence: 99%