Performance of CANDU 6 Steam Generators

Abstract

The trend of increasing Reactor Inlet Header (RIH) temperatures with time in operating CANDU nuclear power stations is a symptom of degrading steam generator performance. Higher RM / temperatures reduce operating margins and if the trend continues, can lead to station derating. This paper investigates the sensitivity of steam generator performance to station operating conditions, tube fouling, variation of recirculation ratio, tube support plate blockage and preheater leakage. It was found that the dominant factor in the degradation of steam generator performance is rube fouling. The evidence suggests that over the first five to seven years of operation the CANDU 6 steam generators have used up approximately one-half of the design fouling margin. The conclusions of this investigation will serve to focus further research effort on the key mechanisms affecting continuing degradation of steam generator performance.