PWR steam generator chemical cleaning process testing in model steam generators

Corrosion related problems in PWR power plant steam generators have caused high maintenance costs, increased radiation exposure to plant personnel, and reduced unit availability. Two cleaning methods were investigated for their ability to clean deposits from steam generators thereby increasing the integrity of the steam generators and reducing personnel radiation exposure, due to reduced maintenance. First, an on-line chemical cleaning process (Chelant Addition) was tested for its ability to prevent corrosion product buildup in a steam generator. Second, an off-line dilute chemical cleaning process was tested to evaluate its ability to remove corrosion product deposits and leave minimal waste for disposal. These two processes were tested in model steam generators which simulated the operating conditions of a typical full size steam generator. Six model steam generators (MSG) were fabricated and qualified for their ability to reproduce denting at tube support plates. The results of six chemical cleaning tests and the post-cleaning destructive metallurgical evaluation of two of the model steam generators are reported