Operating experience from ageing events occurred at nuclear power plants

This paper presents the results of an engineering review of event reports which are related to ageing of nuclear power plants. The term ageing used in this paper refers to the continuous time dependent degradation of structures, systems and components (SSC) during normal service. The events reports analysed were retrieved from the IAEA Incident Reporting System (IRS) database, covering the period 01.01.2008 – 30.06.2018. Initially 173 events were considered candidates to "ageing related events". After deep analysis only 113 events were selected for this study. In order to characterise this set of 113 events, the events were classified according to 9 categories (or groups) and 64 families (or sub-groups). The most relevant categories are systems and components affected, direct and root causes and ageing mechanisms involved. In addition to the event characterisation, the review of the operating experience led to the identification of 10 high-level lessons learned (i.e.: applicable to a wide range of reactor technologies and operational situations), based on numerous more event-specific insights. These lessons learned cover issues such as hidden deficiencies in design visible in aged components only after many years of plant operation, deficiencies in ageing and maintenance programmes, accelerated ageing or the adequacy and effectiveness of the inspection and monitoring methods. This study shows that, in many cases, ageing related events involve equipment important to safety, challenge performance of SSC intended functions and lead to plant transients such as a reactor trip or actuation of plant engineered safety features.

BALLESTEROS AVILA Antonio;  PEINADOR VEIRA Miguel; 

2021-09-20

INFORUM VERLAGS-VERWALTUNGSGESELLSCHAFT MBH

JRC124248

1431-5254 (online),   

https://www.kernd.de/kernd-en/fachzeitschrift-atw/hefte-themen/2021/,    https://publications.jrc.ec.europa.eu/repository/handle/JRC124248,