Empirical study on human error probability of procedure-extraneous behaviors

•The error probability of procedure-extraneous behaviors was empirically estimated.•HuREX data was analyzed by the Poisson regression technique.•Occurrence rates were predicted with the effects of two significant PSF variables. To realistically quantify human reliability in socio-technical systems, it is useful to obtain statistical evidence from empirical data. A procedure-extraneous error, which is a type of commission error, can occur when an operator attempts to operate a system or component that is not guided in the relevant procedure. Because these behaviors are rarely found in system environments in which the procedures are strictly followed, they have not been sufficiently studied from a quantitative point of view. This study aims to estimate the occurrence probability of procedure-extraneous behaviors based on data from a full-scope simulator of a nuclear power plant. For this analysis, 107 simulation records of the APR1400 plant and human errors identified by experts in various fields were analyzed by Poisson regression. Using the resulting coefficient estimates from the regression model, the expected recovery probabilities, and the performance time required for human events, the occurrence probability of procedure-extraneous behavior was predicted. Depending on the situation and recoverability, various values of human error probability were derived between 1 and 10−6. Limitations from data scarcity and the implications of the results are discussed.