Dynamic methodologies for reliability and probabilistic risk assessment (PRA)

Dynamic methodologies in reliability and PRA are those that explicitly account for the time element in probabilistic system evolution. Dynamic methodologies are usually needed when the system has more than one failure mode, control loops, and/or hardware/process/ software/human interaction. An overview of the dynamic methodologies proposed to date is given, including those that use dynamic event tree generation, continuous time-state space representation, the cell-to-cell mapping technique and graphical schemes. The use of dynamic methodologies for state/parameter estimation in on-line applications is also discussed. Potential on-line use of dynamic methodologies as operator assistance tools for risk informed accident management or normal operation is described and illustrated.