Correlation between events with different safety significance in nuclear power plants

The main purpose of collecting and analyzing operating experience events is to look for insights to improve safety. The underlying assumption is the correlation and causality between events with different safety significances. The analysis of this assumption could be valuable to optimize operating experience feedback programs and to enhance safety. This paper analyses the correlation between events with different safety significances. Groups of events from six nuclear energy related databases are considered. The findings are that a correlation exists but with various levels and not as large or consistent as might be expected across different databases. These results might be the basis for further work to analysis causality, to find out how a similarity in causes influences the correlation, and finally to improve the operating experience program.