Representing cognitive activities and errors in HRA trees

Abstract A graphic representation method is presented herein for adapting an existing technology—human reliability analysis (HRA) event trees, used to support event sequence logic structures and calculations—to include a representation of the underlying cognitive activity and corresponding errors associated with human performance. The analyst is presented with three potential means of representing human activity: the NUREG/CR-1278 HRA event-tree approach; the skill-, rule- and knowledge-based paradigm; and the slips, lapses, and mistakes paradigm. The above approaches for representing human activity are integrated in order to produce an enriched HRA event tree—the cognitive event tree system (COGENT)—which, in turn, can be used to increase the analyst's understanding of the basic behavioral mechanisms underlying human error and the representation of that error in probabilistic risk assessment. Issues pertaining to the implementation of COGENT are also discussed.