A computerized tool to evaluate the cognitive compatibility of the emergency operational procedures task flow

Nuclear power production is a safety-critical process where ultimate decisions lie with the operators. During postulated incidents and accidents, operators rely on emergency operational procedures (EOPs), which are the most used decision support tool. In this research we present a method to develop a computerized tool, based on the ACT-R cognitive architecture, to evaluate the logical task flow in the EOPs, verifying if the timing assumptions for operator's actions contained in the procedure scripts can be accomplished by the human operators. We apply the tool to model the nuclear power plant (NPP) operator crew tasks during a Loss of Coolant Accident (LOCA) simulation. To validate the procedural scripts, the tool calculates the time intervals that operators need to accomplish actions and compare these time intervals with the plant dynamic behavior during the evolution of the accident. The tool proved to be an adequate way to validate the logical task flow of the EOP analyzed, showing that operators have enough time to execute their actions and an adequate waiting (free) time between some of their actions. The developed tool provides a low cost alternative solution for NPPs owners and regulatory bodies to validate the logical task flow and quality issues of the hundreds of NPPs procedures.