Mixed model usability evalution of the SPAR-H human reliability analysis method

The SPAR-H method is a simple, easy to understand, and readily applied human reliability analysis (HRA) method developed at the Idaho National Engineering and Environmental Laboratory (INEEL) for the US Nuclear Regulatory Commission (NRC). The SPAR-H method supports the development of Standardized Plant Models for probabilistic risk assessment (PRA), event analysis at US commercial nuclear facilities, and the significance determination process portion of the Reactor Oversight Process. Usability evaluation, an approach established in the human-computer interaction (HCI) literature, is being applied to better the method. The SPAR-H method was developed over a number of years, and the usability has been assessed via a combination of external and internal development processes. Experience gained from the use of these methods and subsequent refinements resulting from this experience have improved the SPAR-H method's ability to support PRA applications. This is an ongoing, iterative process. This paper presents the refinement of the SPAR-H method as a function of experience gained during the usability assessment conducted as part of methods development. The discussion interprets findings in terms of usability principles and suggests areas for further development.