Overview on technological and operational aspects of PLIM

Full text: Loviisa NPP with two VVER 440 units is owned and operated by Fortum. In year 1997 after the power uprating and relicensing project a comprehensive life management strategy with a target lifetime of 50 years was selected as a key issue for the remaining lifetime. Two licensed fuel suppliers as well as the successful power uprating assist with long-term economy of production. The plant has recently established a life management programme (LMP), which should improve and unify the present programmes and separate ageing projects. The scope of the new LMP of the Loviisa NPP comprises the scientific and analytic research of the ageing phenomena as well as routine repairs and preventive maintenance at the site. On one hand, the work emphasises practical repair and replacement of active components, and, on the other hand, the structural and safety review of the passive nonreplaceable main components as well. The goal of the development is that all maintenance and inspection activities should support plant life management. In general, an effective approach of ageing management of systems, structures and components (SSC) is a mixture of four elements: careful operation and maintenance, replacement strategy, technical modifications of SSCs and mitigation of analysed ageing effects. Therefore, at Loviisa the organisation and functions of LMP are included as far as possible in the normal operating organisation. Thus the practical LMP program includes effective links from operating experiences to the ageing database and also to the long-term decision making. The difficulty in the implementation of the LMP is to apply an adequate and balanced approach through all areas and important components in long-term. Therefore, such assessment tools as cost-benefit analysis and classification of components according to their impact on safety and operation is needed. During the past few years, the most important ageing attributes of main passive components and safety systems of the Loviisa NPP were stored into a specified life management database. The database has links to various archives and databases, which include additional component specific ageing data. Full-time plant life management engineers are responsible for the system specific databases. The person in charge updates the ageing information of his systems into the ageing specific database and makes the proposals for modification or repair work as well as changes to the preventive maintenance program based on analysis and engineering judgement information. Ideally the detailed evaluation of safety significance and ageing sensitivity of the SSCs should be based on expert opinions, analysis of the operating experiences, safety classification and probabilistic safety analyses. In the year 2002 a special group of 'ageing engineers' was chosen at the Loviisa plant for coordinating necessary ageing analysis. At Loviisa NPP the modernisation of automation is the most important plant life management issue at the moment. The existing automation and instrumentation will be replaced within the next ten years by new type of automation. The work for preliminary scheduling and scoping of the modernisation of automation is going on. (author)