Optimization of bearing-inspection intervals

The topic of this paper is the optimization of inspection intervals for the motor-pump set of the AFW system (auxiliary feedwater system) in a nuclear plant. The report focuses on plain hydrodynamic bearings and thrusts. The bearings inspection task requires the disassembly of the pump which is expensive and has not proved to be necessary so far. This paper shows the advantages of the combined use of experts judgments (for the selection of external influent parameters), physical modelling (for the quantification of wear) and operating experience (for the evaluation of failure rates). Physical modelling is very important indeed when poor information is available and especially when experts opinions are missing due to a poor number of operating hours.