European Clearinghouse: Analysis of events related to modifications of nuclear power plants - Summary report of an European Clearinghouse topical study

Abstract

Modifications are implemented in Nuclear Power Plants (NPP) for many different reasons: for safety reasons (for instance, following a Periodic Safety Review), for economic motivations (power uprate or optimization of maintenance activities), to correct existing failures or deficiencies or to cope with the plant ageing. It can be expected that the number of modifications will increase over the coming years, for the operating NPPs but also for the NPPs under construction, considering the life time of the NPPs and the continuous upgrading of safety, security and environmental requirements. It must be ensured that all modifications are designed, implemented and tested in such a manner that the safety of the plant as well as the safety of workers and environment is not degraded. This Summary Report presents the results of a study performed by the European Clearinghouse on Operating Experience Feedback of NPP with the support of IRSN (Institut de Sûreté Nucléaire et de Radioprotection) and GRS (Gesellschaft für Anlagen und Reaktorsicherheit mbH). This study covers NPP events related to modifications to Structures, Systems and Components, to process software, to operational limits and conditions, to operating procedures and to management systems, considering both permanent and temporary modifications.