Analysis of Unexpected Reactor Trips from the Perspectives of Safety I and Safety II

This study attempts to analyze event reports of unexpected reactor trips from the perspectives of Safety I and II. This study reviewed 222 event reports released in the OPIS since 2003, based on the characterized resilience model for unexpected reactor trips in NPPs. Then, correlation analysis between the investigated database, i.e., the data of characterized resilience factors on each event, and event severity, has been carried out from the perspective of Safety I and II. This study attempts to analyze event reports of unexpected reactor trips from the perspectives of Safety I and II. This study reviewed 222 event reports released in the OPIS since 2003, based on the characterized resilience model for unexpected reactor trips in NPPs. Additionally, event severity evaluation on each event was performed by the procedure of quantitative event severity evaluation. Then, correlation analysis between the analyzed data and event severity was performed on the perspective of Safety I and II. As a result, analysis on the perspective of Safety II shows correlation coefficient -0.585 with significance level, while that of Safety I is not satisfied with significance level. Through this results, Safety II concept may be more reasonable and adequate than Safety I in NPPs. So therefore, it needs more application to the different situation, and is necessary to support conventional safety assessment methods with Safety II concept.