Expert judgments for performance shaping Factors’ multiplier design in human reliability analysis

•Utilization of expert judgment and empirical data to derive the multipliers of performance shaping factors (PSFs).•Application of absolute probability judgment (APJ) and ratio magnitude estimation (RME) methods.•Suggestion of PSF multiplier design for digital control rooms. Human reliability analysis (HRA) still heavily relies on expert judgments to generate reliability data. There exists a widely recognized need to validate and justify the reliability data obtained from expert judgments. For demonstrating such effort, we provide a template of how we base expert elicitations and empirical studies to derive the multipliers of performance shaping factors (PSFs). We applied two expert judgment techniques—absolute probability judgment (APJ) and ratio magnitude estimation (RME)—to update the PSF multiplier design in Standardized Plant Analysis of Risk-Human Reliability Analysis (SPAR-H). Licensed operators (N = 17) from a nuclear power plant were recruited. It is found that APJ and RME have acceptable inter-rater reliability and convergent validity between them. The multipliers estimated by APJ and RME were compared with those from empirical studies in the human performance literature. Certain consistencies between these heterogeneous data sources were found. Combining these heterogeneous data, we suggested the multiplier design of PSFs for SPAR-H. We also bridged the relationship between every PSF and its psychological mechanism to trigger human errors. Our work might suggest the appropriateness of expert elicitations in generating useful data for HRA, and strengthen the empirical and psychological foundations of PSF-based HRA methods.