Results of Analysis of Aging Related Events at Ukrainian NPPs

The design lifetime (30 years) of Ukrainian NPPs has already been expired or will be expired soon. One of the priority areas for the development of nuclear energy is long-term operation (LTO) based on the results of periodic safety review. At present, eleven Ukrainian NPP units are operated under LTO conditions, which in turn causes certain features of operation related to wear, fatigue and general aging of components and structures. An issue of aging management is considered one of the main factors to ensure the safety of a nuclear installation, both in the design lifetime and in the long-term operation. The primary purpose of aging management is to ensure the safety and maximum efficiency of operation through the implementation of technically and economically feasible measures aimed at timely detection and keeping of degradation of NPP components caused by aging within the limits. One way to determine the efficiency of implemented measures and aging management programs is to analyze operational experience and, in particular, analyze the number of NPP operational occurrences during the design and long-term operation period and that are directly related to the aging effects. This paper presents the results of the analysis of the events at Ukrainian NPPs caused by aging processes, compares the results of national and international experience.