Modeling nuclear power plant operator knowledge and procedural adherence in the ADS-IDAC simulation model

The omission of procedure steps and the inappropriate execution of knowledge-based actions can represent a significant source of human error during nuclear power plant accidents. Recent improvements in the Accident Dynamics Simulator with the Information Decision and Action in a Crew Context (ADS-IDAC) cognitive simulation model have enhanced the ability to systematically predict the situational contexts that might lead to these incorrect actions. ADS-IDAC links safety functions and plant components with a diagnosis engine in order to determine the relevance of procedural actions and memorized rules to an operator's perceived situational assessment. This relevance score influences the branching probability that the control room crew will skip procedure steps or execute knowledge-based actions. By generating a discrete dynamic event tree based on these branching probabilities, ADS-IDAC provides the human reliability analyst with both the contextual environment that might lead to an inappropriate action and the consequences of such an action.