Optimum stochastic inspection policies for a system with safety device

In this paper we discuss an optimal stochastic inspection policy for systems that consist of a satefy related module which is supervised by a second module. The life time distributions of the modules are arbitrary. A failure of the safety relevant module is determined by the supervising module provided the latter is functioning. Function of the supervising module can be determined only upon inspection. An inspection returns the system into a state as good as new. The system fails if the safety relevant module fails undetected. The optimal inspection policy is searched among stochastic strategies, i.e. strategies that are able to consider different inspection times with various probabilities. Copyright (C) 1996 Elsevier Science Ltd