ENS 47744
ENS Event | |
|---|---|
18:20 Mar 14, 2012 | |
| Title | Unit 3 Steam Generator Tubes Failed In-Situ Pressure Testing |
| Event Description | On January 31, 2012, Unit 3 was shut down due to detection of a tube leak in one Steam Generator (SG). The shutdown was previously reported on Event Notification # 47628. Southern California Edison (SCE) has been performing in-situ pressure testing with non-radioactive water on tubes with significant wear indications. 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.
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. These occurrences are reportable as an 8-hour notification to the NRC in accordance with 10 CFR 50.72(b)(3)(ii)(A). Testing and inspection of Unit 3 steam generator tubes is ongoing to determine the extent and cause of the observed wear. A follow-up notification will be made for additional in-situ pressure test failures. The extent and cause of the condition will be addressed in the follow-up licensee event report that will be submitted in accordance with 10 CFR 50.73(a)(2)(ii)(A). Defective tubes will be removed from service as required prior to Unit 3 plant startup. Unit 2 has been shut down since January 9, 2012 for a scheduled refueling outage. SCE previously performed in-situ pressure testing of the tube with the most wear in Unit 2. Results from this test demonstrated that the tube met the target performance criteria. The NRC Resident Inspector has been notified of this event.
In-situ pressure testing on Unit 3 steam generator tubes was started on March 14, 2012 and is ongoing. On March 15, 2012, 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. Testing and inspection of Unit 3 steam generator tubes is ongoing to determine the extent and cause of the observed wear. Follow-up notifications will be made for any additional in-situ pressure test failures." The licensee notified the NRC Resident Inspector. Notified R4DO (Cain).
In-situ pressure testing on Unit 3 steam generator tubes was started on March 14, 2012 and is ongoing. On March 16, 2012, one additional tube in Unit 3 SG E088 did not meet the target performance criteria of three-times normal pressure conditions as follows: at 1216 PDT, Tube R99 C81 failed at 5,026 psig. Testing and inspection of Unit 3 steam generator tubes is ongoing to determine the extent and cause of the observed wear. Follow-up notifications will be made for any additional in-situ pressure test failures. The licensee notified the NRC Resident Inspector. Notified R4DO (Cain). |
| Where | |
|---|---|
San Onofre  California (NRC Region 4) | |
| Reporting | |
| 10 CFR 50.72(b)(3)(ii)(A), Seriously Degraded | |
| Time - Person (Reporting Time:+0 h0 days <br />0 weeks <br />0 months <br />) | |
| Opened: | Ryan Treadway 18:20 Mar 14, 2012 |
| NRC Officer: | John Knoke |
| Last Updated: | Mar 16, 2012 |
| 47744 - NRC Website | |
Unit 3 | |
|---|---|
| Reactor critical | Not Critical |
| Scram | No |
| Before | Cold Shutdown (0 %) |
| After | Cold Shutdown (0 %) |
WEEKMONTHYEARENS 477442012-03-14T18:20:00014 March 2012 18:20:00
[Table view]10 CFR 50.72(b)(3)(ii)(A), Seriously Degraded Unit 3 Steam Generator Tubes Failed In-Situ Pressure Testing 2012-03-14T18:20:00 | |