A system for improved reliability operations of a system with a heat recovery steam generator (HRSG) are presented. The system includes a processor configured to execute a model library to model a safety system. The model library includes a plurality of subsystem models each configured to derive a reliability measure. The system also includes the HRSG and an HRSG advisory system. The HRSG advisory system may be executed by the processor and is configured to receive one or more condition monitoring algorithm results, receive one or more measurements; and determine a probability of failure for the HRSG based at least in part on the one or more condition monitoring algorithm results, the one or more measurements, the model library, or a combination thereof. Moreover, determining the probability of failure includes determining a most likely state of a plurality of states of the HRSG.