Overview of plant life management for long term operation in nuclear power plants

Many IAEA member states have given high priority to licensing their nuclear power plants to operate for terms longer than the time frame originally anticipated (generally 40 years). The task of managing plant ageing is assigned in most member states to an engineering specialty called 'plant life management' (PLiM) applying a systematic analysis methodology to System Structure Components (SSCs) ageing. In many countries, the safety performance of nuclear power plants is periodically assessed and characterized via the periodic safety review (PSR) process. Regulatory review and acceptance of PSRs constitutes for these countries the licensing requirement for continued operation of the plant to the following PSR cycle (usually 10 years). In the USA and in other countries operating US designed plants, instead of PSR process, a license renewal application (LRA) process is followed, which requires certain prerequisites such as ageing management programs, particularly for passive irreplaceable SSCs. Active components are normally addressed via the maintenance rule (MR) requirements and other established regulatory processes. A third group of member states have adopted a combined approach that incorporates elements of both the PSR process and selected LRA specific requirements, such as time limited ageing analysis. The article ends with some IAEA recommendations for the implementation of national PLiM programs