Calculating nominal human error probabilities from the operation experience of domestic nuclear power plants

•HEP (human error probability) is critical input for a risk assessment.•Event report is an important source for estimating nominal HEPs.•13 event reports issued from a regulatory body are investigated.•Nominal HEPs 15 task types are estimated from event investigation reports. It is evident that human reliability analysis (HRA) practitioners require a large spectrum of HRA data that are indispensable not only for understanding the cause of a human error but also for estimating its human error probability (HEP) under a given task context. Accordingly it is very important to collect HRA data from diverse sources as much as possible, which should be done based on a firm technical underpinning. In this regard, Park et al. proposed a novel framework that allows us to systematically calculate the number of task opportunities from the investigation reports reflecting the operation experience of domestic nuclear power plants [1]. In this study, based on the proposed framework, the nominal HEPs of 15 task types are quantified based on the number of task opportunities calculated from the 13 investigation reports stemming from diverse human errors. Although there are several limitations to be technically resolved, the results of this study are meaningful because we are able to take the first step in securing HRA data from investigation reports that reflect the operation experience of domestic NPPs.