ENS 44102
ENS Event | |
|---|---|
20:45 Mar 27, 2008 | |
| Title | Unacceptable Flaw Found in Rpv Cap to Pipe Weld |
| Event Description | At 1645 EDT, it was determined that an unacceptable flaw existed in reactor pressure vessel penetration N9. This penetration leads to a capped line and the flaw is in the cap-to-pipe weld. Based on manual ultrasonic examination, the flaw is 6.2 inches in length on a 5.5 inch OD pipe. Using non-qualified ultrasonic sizing techniques, the flaw is estimated to have a maximum depth of 30 percent through-wall. The flaw was discovered during in-service inspection examination of this penetration, using an improved technique compared to the technique used during a 2004 inspection. The flaw has been found unacceptable per paragraph IWB-3514.4 of the 1989 Edition of ASME Section XI Code and is therefore reportable. A weld overlay repair is being planned.
The safety significance of this is minimal. Unit 1 is currently in a refueling outage. Repairs of the affected weld will be completed prior to startup. The licensee notified the NRC Resident Inspector.
On March 27,2008, at 2027 hours0.0235 days <br />0.563 hours <br />0.00335 weeks <br />7.712735e-4 months <br />, the Control Room Supervisor made a notification (Event Number 44102) to the NRC Operations Center in Accordance with 10 CFR 50.72(b)(3)(ii)(A) (i.e., any event or condition that results in the condition of the nuclear power plant, including its principal safety barriers, being seriously degraded). The notification was made as a result of determining that an unacceptable flaw existed in the reactor pressure vessel penetration N9 (control rod drive system return line) nozzle-to-pipe cap weld. At the time of discovery, based on manual ultrasonic examination, the flaw was determined to be 6.2 inches in length on a 5.5-inch OD pipe. Using non-qualified ultrasonic depth sizing techniques, the flaw was estimated to have a maximum depth of 30 percent through-wall. The flaw was found unacceptable in accordance with paragraph IWB-3514.4 of the 1989 Edition of ASME Code,Section XI and therefore was reportable. Basis for Retraction On March 30, 2008, manually indexed phased-array ultrasonic examination of the CRD return line nozzle-to-array caw weld was preformed. Based on these inspections, it was determined that the indication does not exhibit stress corrosion cracking characteristics and is not consistent with ultrasonic responses associated with inside diameter (ID) connected geometry. Therefore, the CRD return line nozzle-to-pipe cap weld is acceptable from an ASME Code Section XI perspective. On this basis, the indication did not result in the condition of the nuclear power plant, including its principal safety barriers, being seriously degraded and the issue is not reportable under 10 CFR 50,72(b)(3)(ii)(A). Investigation of this condition is documented in the corrective action program in Nuclear Condition Report (NCR) 272454. The NRC resident was notified of this retraction. Notified R2DO (Vias). |
| Where | |
|---|---|
Brunswick  North Carolina (NRC Region 2) | |
| Reporting | |
| 10 CFR 50.72(b)(3)(ii)(A), Seriously Degraded | |
| Time - Person (Reporting Time:+-0.3 h-0.0125 days <br />-0.00179 weeks <br />-4.1094e-4 months <br />) | |
| Opened: | Tom Hackler 20:27 Mar 27, 2008 |
| NRC Officer: | Pete Snyder |
| Last Updated: | May 23, 2008 |
| 44102 - NRC Website
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WEEKMONTHYEARENS 569742024-02-17T13:37:00017 February 2024 13:37:00
[Table view]10 CFR 50.72(b)(3)(ii)(A), Seriously Degraded Primary Containment Degraded ENS 441022008-03-27T20:45:00027 March 2008 20:45:00 10 CFR 50.72(b)(3)(ii)(A), Seriously Degraded Unacceptable Flaw Found in Rpv Cap to Pipe Weld 2024-02-17T13:37:00 | |