Overview of Plant Life Management for Long Term Operation in Nuclear Power Plant

Nuclear power plants provide secure and sustainable energy supplies, however safety should always be the prime consideration. Plant operators and regulators need to take the necessary steps to ensure that plant safety margins are maintained and, where possible, even enhanced throughout the plant’s operating life. At the end of 2013, there were 434 nuclear power reactors in operation worldwide, with a total capacity of 371.7 GW(e). This represents a slight decrease of some 1.6 GW(e) in total capacity, compared to the 2012 figures. There were only three new grid connections while four reactors were officially declared permanently shut down. Many Member States have given high priority to licensing their nuclear power plants to operate for terms longer than the time frame originally anticipated (e.g. 30 or 40 years), approximately 80% had been in service 20 years and more. 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 NPPs 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 a PSR process, a license renewal application (LRA) process is followed, which requires certain prerequisites such as ageing management programmes, 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. Taking into account this variety of approaches, the IAEA initiated work to collect and share information among Member States on good practices in PLiM for LTO in nuclear power plants, by comparing the various approaches to the PSR reference and by drawing lessons learned from relevant applications and experiences