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1. Definition of erosion The erosion (wastage) of the steam generator heat transfer tube refers to the corrosion failure mode in which the wall of the heat transfer tube is uniformly thinned under a specific local environment. It is one of the typical corrosion problems of early pressurized water reactor steam generators. 2. Core Causes: Early pressurized water reactor steam generators used Inconel 600 pipes, and the secondary side water was chemically treated with phosphate. Sodium phosphate was locally concentrated in the gaps between the heat transfer tubes and the support plates and in the areas where sludge accumulated, eventually causing the tube walls in these areas to be corroded and thinned. 3. The main impact directly causes the thickness of the heat transfer tube wall to decrease, and in severe cases may cause the heat transfer tube to rupture, which is one of the causes of steam generator heat transfer tube rupture accidents (SGTR) in history. This forces nuclear power plants to shut down frequently to conduct additional inspections of heat transfer tubes, which significantly increases operation and maintenance costs. Some power plants even replace steam generators in advance as a result. 4. Protection and detection At present, the industry has changed the phosphate treatment of the secondary side water to fully volatile treatment (AVT), and added ammonia to the strictly purified feed water, which has greatly reduced the incidence of heat transfer tube corrosion. In daily operation and maintenance, eddy current testing, ultrasonic thickness measurement and other methods can be used to monitor the thinning of the pipe wall and identify risks in a timely manner.