Development of new methods for human reliability analysis

Abstract

The safe operation of nuclear power plants (NPPs) is substantially dependent on the performance of human operator. The occurrences of human errors have been considered to cause the serious problems in the plant systems. In this regard, in order to understand the nature of human errors and estimate the probabilities of them, various human reliability analysis (HRA) methods have been implemented. Recently, in HRA community, some significant issues have been raised. The first issue is the adoption of an advanced main control rooms (MCRs) in NPPs, and the second issue is the importance of human actions during the low power and shutdown (LPSD) operations. Even the behavioral characteristics of operators are significantly changed in both conditions, the existing HRA methods were developed for the conventional MCR and full power operation of NPPs. The aims of this study are to (1) develop an operators’ diagnosis error assessment method in the advanced MCR and (2) develop a PSFs’ weightings quantification method during LPSD operation. Basically, in this study, the processes were identical for both parts: (1) assessment of the human error probabilities (HEPs), (2) analysis of the performance shaping factors (PSFs), and (3) suggestion of the nominal HEPs. In addition, as data source, full-scope simulators of the advanced MCR and domestic operational experience during were utilized, respectively. As a result, in the case of the first part, the evaluation method of PSFs’ weightings, and the estimation method of diagnosis error probabilities in the advanced MCR were suggested. In the case of the second part, the evaluation method of PSFs’ weightings and database (DB) of the HEPs during the LPSD operations were provided.