Developing probabilistic safety performance margins for unknown and underappreciated risks

Allan Benjamin, Homayoon Dezfuli and Chris Everett

Reliability Engineering and System Safety, 2016, vol. 145, issue C, 329-340

Abstract: Probabilistic safety requirements currently formulated or proposed for space systems, nuclear reactor systems, nuclear weapon systems, and other types of systems that have a low-probability potential for high-consequence accidents depend on showing that the probability of such accidents is below a specified safety threshold or goal. Verification of compliance depends heavily upon synthetic modeling techniques such as PRA. To determine whether or not a system meets its probabilistic requirements, it is necessary to consider whether there are significant risks that are not fully considered in the PRA either because they are not known at the time or because their importance is not fully understood. The ultimate objective is to establish a reasonable margin to account for the difference between known risks and actual risks in attempting to validate compliance with a probabilistic safety threshold or goal. In this paper, we examine data accumulated over the past 60 years primarily from the space program, and secondarily from nuclear reactor experience, aircraft systems, and human reliability experience to formulate guidelines for estimating probabilistic margins to account for risks that are initially unknown or underappreciated. The formulation includes a review of the safety literature to identify the principal causes of such risks.

Keywords: Probabilistic; Safety performance margin; Safety performance requirement; Safety threshold; Safety goal; Unknown risk; Underappreciated risk (search for similar items in EconPapers)
Date: 2016
References: View complete reference list from CitEc
Citations: View citations in EconPapers (1)

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Persistent link: https://EconPapers.repec.org/RePEc:eee:reensy:v:145:y:2016:i:c:p:329-340

DOI: 10.1016/j.ress.2015.07.021

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