Long term operation: Maintaining safety margins while extending plant lifetimes [Session summary]

Long term viability of the nuclear industry begins with a strong focus on safe daily operations at each nuclear facility. This focus begins with the chief executive officer and extends to every operator and worker at a nuclear facility. It can be shared, but never delegated. At the end of the day, nuclear safety is a dynamic non-event. Some countries view LTO in terms of a continuous process as opposed to periods of prescribed operation. Despite differences in framework, there is much in common with each approach. It is important to identify both the commonalities and differences associated with each methodology. It was noted that the difference in approaches to normal and LTO is not too large, but the issues to be addressed are different. Further work and, in particular, international cooperation is needed to harmonize requirements on adequate safety levels to be achieved and maintained during long term operation. Special attention is required to ensure safe LTO, in particular, for older plants designed to earlier standards in connection with ageing, less well documented design bases, and the large scope of modifications required. Safe LTO will only be ensured if plants are managed in an appropriate manner. The most significant events within the past ten years provide good evidence that increasing effort is needed to develop and maintain effective safety management systems. If available, the lessons learned from similar installations in the country can be very useful to plan an adequate LTO programme. But if the type of facility should be unique (e.g. fuel fabrication plants), the experience gained in other countries will help to understand good safety practices, good safety design, etc. The establishment and maintenance of international databases on LTO, including related issues, such as ageing, as well as the experience gained in the LTO of nuclear facilities, and results from international research programmes, are of high importance. Strengthening international activities between the IAEA, regulatory authorities and utilities can bring mutual benefits to those countries that are at different stages of addressing the issue of LTO. The related IAEA activities can provide guidance on the scope and content of programmes to ensure safe LTO. Safety margins are changing during normal as well as LTO in connection with the development of safety requirements, safety assessment tools and plants' modifications. In addition to technical issues, losing competence is one of the key future challenges. Conceptual solutions need to be developed