Methodology for Ranking of the NPP Krsko PSR Issues

A Periodic Safety Review (PSR) of a nuclear power plant, typically, results with a number of identified issues of different types. According to the current IAEA's referential PSR guiding document, the overall review is divided into fifteen review areas, termed 'safety factors', which range from 'plant design' to 'human factors' to 'safety culture', for example. The method for ranking of identified safety issues must characterize the safety importance of the issues coming from different review areas or factors on the same scale and consistent basis. For the Krsko NPP's (NEK) second PSR, the method for issue ranking was established which primarily evaluates the safety significance of any PSR issue by considering its impact on the defense in depth. This impact can be evaluated qualitatively or quantitatively. The paper presents the methodology and illustrates its application on a selected simple example.(author).