Suggested improvements to the definitions of Standardized Plant Analysis of Risk-Human Reliability Analysis (SPAR-H) performance shaping factors, their levels and multipliers and the nominal tasks

• The SPAR-H guidelines should be revised.
• Descriptions of the PSFs should be improved.
• New definitions should reduce overlap between the PSFs.
• The multipliers are based on an “old” method and should be revised.
• Some PSF levels and multipliers in SPAR-H are not logical.

This paper discusses the definitions and content of eight performance shaping factors (PSFs) used in Standardized Plant Analysis of Risk-Human Reliability Analysis (SPAR-H) and their levels and multipliers. Definitions of nominal tasks are also discussed. The discussion is based on a review of literature on PSFs, interviews with consultants who have carried out SPAR-H analysis in the petroleum industry and an evaluation of human reliability analysis reports based on SPAR-H analysis. We concluded that SPAR-H definitions and descriptions of the PSFs are unclear and overlap too much, making it difficult for the analyst to choose between them and select the appropriate level. This reduces inter-rater reliability and thus the consistency of SPAR-H analyses. New definitions of the PSFs, levels and multipliers are suggested with the aim to develop more specific definitions of the PSFs in order to increase the inter-rater reliability of SPAR-H. Another aim was to construct more varied and more nuanced levels and multipliers to improve the capacity of SPAR-H analysis to capture the degree of difficulty faced by operators in different scenarios. We also suggest that only one of two nominal SPAR-H tasks should be retained owing to the difficulty in distinguishing between them.