Harmonisation of surveillance requirements and maintenance in a context of ageing and obsolescence based on reliability, availability and risk information

[EN] This paper contains the fundamentals and a comparison of different alternatives in the context of risk-informed surveillance requirements that consider the full effects of implementing the maintenance rule. A case study is included to demonstrate the performance of the different alternatives, which focus on a motor-operated valve and make use of an Ageing PRA to quantify the effect of component ageing, test and maintenance effectiveness on equipment RAM and its impact on risk. The results show that the alternative that simultaneously harmonises surveillance requirements and maintenance activities provides the best results in terms of RAM and risk in a context of equipment ageing and obsolescence. However, they also show that measures other than simply readjusting surveillance testing and maintenance intervals should be explored in case of technical obsolescence, as this has a strong impact on maintenance effectiveness, which may require, for example, an obsolescence management program to be applied.