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Probabilistic Risk Assessment

ORNL has developed a time-dependent reliability analysis tool which is capable of evaluating simulation-based time-dependent component failure rates of risk-important components. The time-dependent rates act as inputs for PRA of complex dynamic systems, such as NHESs. Non-Markovian stochastic Petri nets (SPNs) are used for modeling and evaluation of complex dynamic subsystem interactions and their performance and reliability. The reliability model, coupled with the plant simulator using Modelica-based libraries such as TRANSFORM and the optimizer model in the Risk Analysis Virtue Environment (RAVEN), provides a method for analyzing the evolving performance of complex systems through life as a function of operational history.