During Nuclear power plant (NPP) outages, communications between outage participants (e.g., workers, managers, engineers) can be tedious and error-prone due to complicated organization of outage processes and crews, the extremely busy schedule with a 10-minute level of detail, and many people working in the field. Therefore, precisely predicting and controlling the time wasted during communications and remedying miscommunications can improve the NPP outage productivity. A communication protocol is a set of rules defining the organization structures, timing, channel, and content of communication according to the information transition needs of a workflow. In order to reduce the time wasted and ineffective information transition due to human errors in communications, the authors propose a communication protocol optimization according to the as-planned workflow. This optimization study evaluates how different communication protocols in an outage workflow will influence the time wasted under the influence of human errors and task duration uncertainties. The simulation results indicate that the proposed method can provide a reliable reference of improving the communication protocol in NPP outage workflows.