Method for assessment of ageing based on PSA results

摘要

Method for prioritization of the nuclear power plant components considering the core damage frequency increase resulting from their ageing is developed and presented. The prioritization of the components is done with sensitivity coefficients obtained from their Fussel-Vesely importance measures and utilization of the Taylor expansion approach. Components are sorted depending on their contribution to the change of the core damage frequency of the plant. The overall change of the core damage frequency resulting from components ageing is assessed for different surveillance and replacement intervals.Developed method is applied on the reference probabilistic safety assessment model of the nuclear power plant. Components ageing rates from the TIRGALEX database are used as input data for the analysis. The main contributors to the increase of the core damage frequency are identified in the obtained results. The implications of extension of test intervals is assessed and presented.The limitations of the developed method and possibilities for future improvement are presented. The major issues considering the introduction of the ageing in the probabilistic safety assessment are discussed.