ENS Event | |
|---|---|
09:14 May 3, 2006 | |
| Title | Degraded Condition |
| Event Description | Greater than one percent of steam generator (SG) 2-4 tubes were determined to be defective and require plugging. Diablo Canyon performs 100% bobbin inspection of SG tubes, thus, no expanded bobbin inspection scope was required.
On May 3, 2006, during the Unit 2 thirteenth refueling outage (2R13), final analysis of eddy current data of SG 2-4 indicated that greater than one percent of the total tubes inspected were defective placing them in Category C-3. Thirty four (34) detective tubes in SG 2-4 were detected and are being plugged. Most of the pluggable indications are due to axial outside diameter stress corrosion cracking at the hot leg tube support plates. Diablo Canyon TS 5.5.9, Table 5.5.9-2, requires 'Notification to NRC pursuant to 10 CFR 50.72(b)(2)' (replaced by 10 CFR 50.72(b)(3)(ii), an 8-hour non-emergency ENS report requirement). An NRC teleconference in accordance with TS 5.6.10.d to report the preliminary SG tube inspection results is scheduled for May 3, 2006, at 1000 PDT. A Special Report in accordance with TS 5.6.10.a to report the number of tubes plugged in each SG, and TS 5.6.10.c describing the cause of the tube degradation and corrective measures taken to prevent recurrence will be submitted prior to returning Diablo Canyon Unit 2 to power operation. The licensee notified the NRC Resident Inspector. |
| Where | |
|---|---|
Diablo Canyon  California (NRC Region 4) | |
| Reporting | |
| 10 CFR 50.72(b)(3)(ii)(A), Seriously Degraded | |
| LER: | 05000323/LER-2006-002 Re Steam Generator Tube Plugging Due to Stress Corrosion Cracking |
| Time - Person (Reporting Time:+3.23 h0.135 days <br />0.0192 weeks <br />0.00442 months <br />) | |
| Opened: | John Macintyre 12:28 May 3, 2006 |
| NRC Officer: | Bill Gott |
| Last Updated: | May 3, 2006 |
| 42547 - NRC Website
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WEEKMONTHYEARENS 561762022-10-23T15:30:00023 October 2022 15:30:00
[Table view]10 CFR 50.72(b)(3)(ii)(A), Seriously Degraded Reactor Coolant System (RCS) Pressure Boundary Degradation ENS 425472006-05-03T09:14:0003 May 2006 09:14:00 10 CFR 50.72(b)(3)(ii)(A), Seriously Degraded Degraded Condition ENS 421362005-11-11T20:00:00011 November 2005 20:00:00 10 CFR 50.72(b)(3)(ii)(A), Seriously Degraded Report of Degraded Condition Due to Defective Steam Generator Tubes ENS 406892004-04-21T01:10:00021 April 2004 01:10:00 10 CFR 50.72(b)(3)(ii)(A), Seriously Degraded Degraded Condition - Greater than One Percent of Steam Generator Tubes Defective ENS 406592004-04-08T20:00:0008 April 2004 20:00:00 10 CFR 50.72(b)(3)(ii)(A), Seriously Degraded Degraded Condition - Greater than One Percent of Steam Generator Tubes Defective 2022-10-23T15:30:00 | |