Russian Federation: Example of an intelligent system of condition monitoring in the context of PLiM and PLEX

Plant life extension beyond the originally anticipated life is one of the main concerns in the nuclear industry of the Russian Federation, as well as abroad. Along with consideration of the accumulated experience gained during LTO of different NPP unit types, in the context of PLEX activities, the set of technical measures designed to ensure safe and reliable operation of NPPs beyond their originally assumed service life should be used to justify LTO. Nuclear power plant LTO stipulates the necessity of changing the traditional approaches applied to conducting an assessment of the degradation rate, also referred to as ageing, in zones mostly subjected to operational loading of equipment important to safety. Considerable work has been done and experience accumulated to justify operation beyond the originally assumed service life of Russian NPPs. In parallel, new approaches have been developed such as the design of new diagnostics tools to help assess operational damage. The approach is based on the application of conventional NDE methods in conjunction with on-line monitoring to determine the consequences of thermal and mechanical loading, such as the actual deformation and loss of structural and functional performance of essential and potentially life limiting equipment. Numerical calculations of the accumulated metal damage detected in the monitored zones can then be conducted more precisely. The block diagram of a life cycle of NPP equipment subject to thermal and mechanical loading is presented. It includes all main sequences in the service life of a safety related component, from its design phase all the way to its decommissioning