An Influence Diagram extension of the Unified Partial Method for Common Cause Failures

Authors: Zitrou Athena, Bedford Tim, Walls Lesley

Management Science Working Paper No. 20 (2005)

If the author is a current member of the Management Science staff then a copy of this paper, as a PDF file, can be obtained free of charge, by emailing the author. The email addresses of staff members can be found on the staff webpage. Please make sure to specify the research paper number when requesting the paper.

Abstract

Email abstract to a colleague

Modelling Common Cause Failures (CCFs) is an essential part of risk analyses, especially for systems such as nuclear power plants, which are required to have high reliability. The Unified Partial Method (UPM) is the de facto approach of the UK for modelling CCFs. However, it has received criticism about some of its features. This paper presents an Influence Diagram model for CCFs, informed by UPM, but attempts addressing its deficiencies by representing uncertainty of system performance, creating a context for using the information in the industry database, and capturing the non-linearity in the way the system defences influence reliability. An expert elicitation process is used to construct the ID model and to identify the non-linear structure of the domain, using an example of Emergency Diesel Generators (EDGs) from nuclear power plants. Insights and experiences from the elicitation process are described.