ENS 40689
ENS Event | |
|---|---|
01:10 Apr 21, 2004 | |
| Title | Degraded Condition - Greater than One Percent of Steam Generator Tubes Defective |
| Event Description | On April 08, 2004, during the Unit 1 twelfth refueling outage (1R12), analysis of eddy current data on [Steam Generator] SG 1-4 indicated that greater than one percent of the total tubes inspected in SG 1-4 were defective. Ninety-two (92) defective tubes in SG 1-4 were detected and are being plugged. Most of the [pluggable] indications are due to circumferential primary water stress corrosion cracking in the Rows 5 to 8 U-bend region. Results of the SG tube inspection fall into Category C-3, which requires a four-hour non-emergency report in accordance with Technical Specification (TS) Table 5.5.9-2 and 10 CFR 50.72(b)(3)(ii) (an 8-hour requirement replacing the former (b)(2)(iii)(C), 4-hour requirement). [This was reported in EN#40659 dated 04/08/04.]
An NRC teleconference in accordance with TS 5.6.10.d to report the results of the voltage-based repair criteria implemented for the tube support plate intersections was conducted on Wednesday April 14, 2004, at 1300 EDT. On April 20, 2004, following completion of SG eddy current testing, PG&E identified SG 1-1 had greater than one percent of the total tubes that were defective. Forty (40) defective tubes in SG 1-1 were detected and plugged. Most of the [pluggable] indications are due to outside diameter stress corrosion cracking at the SG tube to support plate intersections. SG 1-2 had twenty-six (26) and SG 1-3 had twenty-seven (27) defective tubes that required plugging. A Special Report in accordance with TS 5.6.10.a and e will be submitted prior to returning Unit 1 to power operation. A Licensee Event Report in accordance with 10 CFR 50.73(a)(2)(v)(C) will be submitted within 60 days. 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 | |
| Time - Person (Reporting Time:+-1.73 h-0.0721 days <br />-0.0103 weeks <br />-0.00237 months <br />) | |
| Opened: | Jeff Knisley 23:26 Apr 20, 2004 |
| NRC Officer: | Jeff Rotton |
| Last Updated: | Apr 20, 2004 |
| 40689 - NRC Website
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Unit 1 | |
|---|---|
| Reactor critical | Not Critical |
| Scram | No |
| Before | Cold Shutdown (0 %) |
| After | Cold Shutdown (0 %) |
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 | |