Nuclear power plants (NPPs) needs routine shutdowns, known as "outages," for maintenance operations. A typical outage normally takes about 30 days and involve more than 2,000 contract personnel who might not necessarily be familiar with the working procedures and environments. During outages, omission errors (i.e., skip certain steps in a task) could be common and cause delays. Most omission errors are due to forgetting. Poor communication seriously aggravates the impacts of forgetting. While most corrective actions emphasized on conducting post-event meetings to highlight required procedures, forgetting is still unavoidable. To mitigate risks caused by forgetting, the nuclear industry needs properly designed communication protocols - rules that guide participants in distributing information to the right people with the right timings. Unfortunately, limited studies examined "good" communication protocols that could protect outage productivity from forgetting. This paper presents a simulation-based optimization method that focuses on the workflow of pump maintenance activities (visual inspection, pump maintenance, and functional surveillance testing) around cooling towers. The authors also introduce the Ebbinghaus Forgetting Curves as a reference to model the probability of forgetting in the simulation. The proposed optimization will automatically identify proper communication intervals by evaluating the impacts of communication times when forgetting events occur. This optimization aims at minimizing delays of the entire workflow when omission errors occur. Results indicate that the communication protocols identified can significantly reduce risks of delays in outages.