Implementation of a cognitive human reliability model in dynamic probabilistic risk assessment of a nuclear power plant (ADS-IDA)

This research has resulted in the development of ADS-IDA which is an integrated software for performing dynamic probabilistic risk assessment (PRA). Unique features of ADS-IDA include (1) modular structure allowing the code to be used for generic applications, although current implementation includes modules designed for nuclear power plant risk assessment, and (2) implementation of the IDA human reliability model which is a cognitive model of operator actions during accident scenarios.; ADS-IDA can be used to: (1) Perform a full scale dynamic PRA of a nuclear power plant (or other systems by replacing the NPP module with the appropriate model and provide the KBs associated with the operator model). (2) Identify and analyze human errors and their causes including commission and omission errors, as well as the effect of timing of operator response. (3) Run cases not covered by the current PRAs, such as scenarios involving instrument failure or miscalibration. (4) Test the relevance of the emergency operating procedures (or abnormal operating procedures if available). (5) Investigate the effect of different system failure modes, and particularly the time of system mode transition (e.g. failure, termination of operation, repair) on the progression of the accident. (6) Analyze the impact of items 2, 3, and 5 above on the evolution of accident scenarios and the final state of the plant.; ADS-IDA as used to perform a dynamic PRA of an accident initiator at an actual nuclear power plant, demonstrating the capabilities of the methodology both in modeling plant behavior and in simulating operator errors of commission and omission.