A number of probabilistic safety assessment (PSA) studies have been conducted to optimize maintenance activities in nuclear power plants from the viewpoint of safety focusing on the risk of core meltdown. However, even a small-scale incident of component, which never causes the core meltdown, resulted in reactor shutdown and economic losses. Accordingly, in addition to the safety analysis focusing on the risk of core meltdown, it is very useful to develop a simulator that can establish maintenance strategies in terms of availability and economic efficiency of nuclear power plants. We have developed an integrated simulator for the maintenance optimization of light water reactors (LWRs). The concept of the simulator is to provide a method for optimizing maintenance activities for representative components and piping systems comprehensively and quantitatively in terms of safety, availability, and economic efficiency (both from cost and profit) under various maintenance strategies including altering inspection frequency and inspection accuracy, conducting sampling inspection, repairs and/or replacements, introducing various maintenance rules, and long-term fuel cycles. In addition, a function of visualization of the simulated results by a divided multidimensional visualization method has also been developed in order to support a decision-making process for optimizing the maintenance activities.
