Prioritization of components important for safety and sensitive to ageing. Application for TRIGA reactor

Due to potential impact on the SSC performances, the identification of ageing effects and implementation of appropriate methods for mitigation of these effects represents an important preoccupation of many organizations and has received even more attention in the last years in the perspective of Long Term Operation. The efforts used for developing time-dependent reliability models for all SSC could be considerable and may outweigh the benefits, but they are not always necessary, mainly because in some cases, the maintenance, test, inspection and surveillance methods are good provision to mitigate the ageing effects. To efficiently use the limited resources, it is necessary to identify and prioritize the SSC that need time-dependent reliability models by using specific criteria. This paper contributes to the effort of performing an efficient process of evaluation of ageing effects using probabilistic safety assessment models. The paper presents the approach developed for SSC selection, and the results of its application carried out for two particular systems of the TRIGA research reactor.

► The selection approach used 2 criteria: SSC risk importance and vulnerability to ageing. ► The results were combined in decision table for ranking the SSC. ► The results could be useful in performing efficient ageing management activities. ► The results obtained for two systems of TRIGA research reactor are presented. ► Recommended components for implementation of time dependent models in the PSA were identified.