Steam Generator (SG) tube wear was

Steam Generator (SG) tube wear was reported following eddy current inspection of Haiyang Units 1 and 2 and Sanmen Unit 1 AP1000®1 plant sites following the respective first cycles of operation. The observed wear resulted in tube plugging for the affected Steam Generators ranging from a maximum of eleven (11) tubes in one Steam Generator to a minimum zero (0) tubes in one Steam Generator. The total number of tubes per steam generator is 10,025 with a design plugging margin of ten percent (10%) of the total number of tubes. Tube degradation leading to plugging is limited in scope and severity and appears to be tolerated well within the design plugging margin. It is expected that wear rates will decrease over time for active wear sites considering increased amount of mechanical work needed to develop deeper wear indications.