Probabilistic approach in optimization of the reliability of restoration systems working on a waiting mode

Reliability parameters have been analyzed for restoration systems working on a waiting mode. A typical example for such systems are the emergency systems in NPPs. The ready conditions of the systems in both operation and restoration periods are determined analytically. On the base of the mean integral probability, the optimal failure frequency of testing of a subsystem in case of a parallel connection is determined. A Markov model is used for the determination of the failure probability. The time dependence of the ready system conditions in the period between tests is obtained. This method gives an opportunity for an optimization of the testing of safety systems in NPPs. (author)