Advances in Probabilistic Risk Assessment (PRA): a Look Into a Practitioners Toolbox

Abstract

The ever-increasing emphasis on the use of Probabilistic Risk Assessment (PRA) in riskinformed decision making translates into increased expectations relating to PRA applications for the groups tasked with developing and maintaining the facility PRAs. In order to succeed in meeting the demand for PRA work, it is essential to develop methodologies and tools (or utilities) that improve the efficiency with which the PRAs are processed and manipulated to obtain a solution. Examples from the Nuclear Safety Solutions (NSS) PRA Practitioners tool box include utilities for cutting logical loops, optimizing fault trees (to decrease run-times), modularizing fault trees, and converting event trees into high level fault tree logic (an important element if the PRA study is to be used to support a risk monitor such as an Equipment Out-of-Service (EOOS) Monitor). The objective of this paper is be to briefly describe the main features of these utilities, and to illustrate the value they have in terms of improving the efficiency and effectiveness of PRA development and maintenance at NSS.