The use of event-sequence diagrams in probabilistic risk assessment

Although experienced risk managers may have a good idea of the scenarios to use when performing individual plant examinations (IPEs) in response to US Nuclear Regulatory Commission's NRC generic letter 88-20, they must resist the temptation to presuppose which components and systems are significant contributors to risk at a given plant and start the process with a clean slate to define the scenarios to be used in the risk assessment, making the IPE truly plant specific. Event-sequence analysis provides a useful mechanism for laying out and documenting plant-specific scenarios during this process. The history methods, advantage of event sequence analysis is presented.