Основні результати аналізу подій на АЕС України, пов’язаних із захисною оболонкою

The main goal of the analysis of operational events at Ukrainian NPPs and around the world related to the containment was obtaining the general and specific lessons that would prevent the repetition of events in the future. The scope of the analysis covers the structural elements of the containment and other systems necessary to ensure its functioning. During the analysis, operational events are divided into categories (those that affect or may affect the performance of confining functions by the containment and those that do not affect (Category 2). Category 1 includes cases of failure of reinforcing tendons, which can potentially lead to the loss of containment design functions (18 events). These cases have been considered in detail since 1990, taking into account the history and reasons for changes in the design forces of tendons tension. The causes of tendons failure analyzed in detail in this paper show that there is a general coincidence with events identified in the study “JRC Technical Report. Operating experience with containment buildings at nuclear power plants. European Commission. Joint Research Center, 2021”, namely - design lacks, maintenance deficiencies, mechanical failures. The lessons learned and corrective measures implemented in the last 10 years at the Ukrainian NPPs, taking into account the failure statistics, show that the number of tendons failure events in the period from 2000 to 2010 is insignificant, and in the period from 2010 to 2020, failures for ZNPP, RNPP and SUNPP are not recorded. This justify that all implemented corrective measures in general have led to a significant improvement of the situation.