Method of analysing a basic preventive maintenance programme taking into account the feedback of experience from France and abroad: The example of PWR 900 primary coolant pumps

Electricite de France (EDF) has undertaken to define and implement preventive maintenance programmes in relation to the principal equipment of the nuclear power plants it operates. Using the example of the primary pumps of 900 MW(e) PWR units, the paper looks at how these maintenance programmes are analysed by the Institute for Radiation Protection and Nuclear Safety (IPSN) of the Commissariat a l'energie atomique (CEA), focusing particularly on incidents that have occurred at units both in France and abroad and the anomalies discovered in the course of regular visits. The principal areas of concern, as shown by the maintenance reports and by the incidents that have occurred during operation in primary coolant pumps, are the volute seal, the shaft seals, the hydraulic bearing and shaft fissuring. An analysis of the maintenance programme shows that the operations it foresees are aimed not only at anticipating the effects of ageing, but also at preventing the repetition of incidents and anomalies already encountered. This is true particularly for the volute seal and shaft seals, while the anomalies recently encountered in the hydraulic bearing have led to the adoption, in practice, of a higher frequency of inspection than that recommended in the maintenance programme. Finally, in the light of shaft fissuring incidents that have occurred abroad, the paper discusses the advisability of adding a shaft inspection to this programme. (author). 2 figs