Reliability of pumps in systems important for the safety of nuclear power units

The vast majority of pump failures are due to leaks with medium (water oil) leakage through various sealing surfaces. The consequence of such failures was the current repair with replacement of sealing elements and/or lapping of sealing surfaces.Comparison of reliability indicators (mean time between failuresevaluated according to the lower limit) for the current period with the corresponding indicator obtained for theprevious period has been performed.As a result of the analysis it was found out:The criterion for comparative evaluation of averageMTBF was not fulfilled for special sewage pumps.Decrease of average operating time before failure may indicate decrease ofreliability lately for these pumps;For other groups of pumps the average MTBF for the current period is not lower than the average MTBF for the previous period which indicates a sufficient level of pump reliability .In accordance with the results of the analysis and calculated assessments of operational reliability the recommendations are formulated.