Yesterday the Nuclear Regulatory Commission announced it will send an Augmented Inspection Team (AIT) to the San Onofre Nuclear Generating Station to review the circumstances that led to three tubes failing a pressure test at Unit 3. On March 14, 2012, at approximately 1120 PDT, Unit 3 Steam Generator (SG) E088 Tube R106 C78 did not meet the target performance criteria because leakage exceeded 0.5 gallons per minute at the maximum pressure achieved during the test (2,884 psig). This was the leaking tube that resulted in the Unit 3 shutdown.
San Onofre reports more steam generator tube failures to NRC
Subsequently, two additional tubes in Unit 3 SG E088 did not meet the target performance criteria as follows: at 1249 PDT, Tube R102 C78 exceeded 0.5 gallons per minute at 3,268 psig and at 1425 PDT, Tube R104 C78 exceeded 0.5 gallons per minute at 3,180 psig. Southern California Edison released an update to the tests noting that four additional tubes in Unit 3 SG E088 did not meet the target performance criteria of three-times normal pressure conditions as follows: (1) At 1109 PDT, Tube R100 C80 failed at 4,739 psig; (2) at 1437 PDT, Tube R107 C77 failed at 5,160 psig; (3) at 1604 PDT, Tube R101 C81 failed at 4,889 psig; and (4) at 1734 PDT, Tube R98 C80 failed at 4,886 psig.
The California utility will continue in-situ testing, and will update the NRC upon any further findings. Hundreds of Southern California residents gathered about a mile south at San Onofre state beach on the first anniversary of the Fukushima disaster to protest the San Onofre Nuclear Generator Station’s continued operation. Another protest is planned on April 28th, the 26th anniversary of the Chernobyl Nuclear Disaster.