The ever increasing complexity of processing systems and the requirements to be satisfied by the processes make process design and process operation more and more complex. Because of that, the reliability/availability is to be taken into account together with other requirements in process design/synthesis. Similarly, failure analysis is also an important part of process operation. In the current work, it has been shown that in addition to the widely used unit level redundancy, process level redundancy must also be considered in synthesizing a process for satisfying high level availability. Therefore, in case of failure, the determination of the best corrective action must be based on more general process networks than considered before. The proposed procedure determines the best or n-best corrective actions for the most general types of highly complex process networks, e.g., including process level redundancy. The P-graph based procedure is effective in generating corrective action suitable for industrial processes.