ENS 44037
ENS Event | |
|---|---|
02:00 Mar 6, 2008 | |
| Title | Circumferential Piping Crack |
| Event Description | On March 5, 2008, a volumetric ultrasonic examination of a Reactor Coolant to Decay Heat System pipe weld was analyzed and determined to identify an unacceptable indication. This dissimilar metal weld is located on the nozzle to the Decay Heat System drop line piping, which is the common suction line from the Reactor Coolant System and is a 12 inch outer diameter pipe. The indication is circumferential, is 15 inches in length, and reaches a maximum localized depth of 65 percent through-wall in one location. The weld was previously partially inspected during the November 2007 refueling outage using manual ultrasonic examination and no indications were identified. The current inspection was done using newly qualified phased array ultrasonic examination techniques in response to industry operating experience regarding dissimilar metal weld flaws. The indication has been found unacceptable per paragraph IWB 3514.4 of the 1989 Addenda of ASME Section XI without further fracture mechanics analysis and is therefore considered reportable.
Preparations for a weld overlay repair and further confirmatory manual ultrasonic testing examinations are in progress. The licensee notified the NRC Resident Inspector.
On March 8, 2008, further fracture mechanics evaluation of the circumferential indication on the Decay Heat System Drop Line determined that the requirements of the ASME Section Xl pipe code were maintained. Specifically, the acceptance criteria of the 1989 Edition Section XI, Table IWB-3641-1, -2, were met with an allowable value for flaw depth / wall thickness (a/t) of 0.75. Consequently, the 65% through wall indication would be considered acceptable for operation and the Degraded Condition Reporting Criteria would not be exceeded. Therefore, this event is not reportable under any 10CFR50.72 criterion. However, due to industry operating experience with dissimilar metals welds, this notification is being made voluntarily. Confirmatory manual ultrasonic testing examinations were completed which validated the presence of the indication originally found via phased array UT examination techniques. A full structural weld overlay repair is in progress which will be completed before returning Crystal River 3 to power operation. The repair effort has already successfully deposited the first weld layer over the location of the flaw. No Licensee Event Report will be submitted for this event. The licensee notified the NRC Resident Inspector. Notified R2DO(Hopper). |
| Where | |
|---|---|
Crystal River  Florida (NRC Region 2) | |
| Reporting | |
| 10 CFR 50.72(b)(3)(ii)(A), Seriously Degraded | |
| Time - Person (Reporting Time:+-3.67 h-0.153 days <br />-0.0218 weeks <br />-0.00503 months <br />) | |
| Opened: | John Taylor 22:20 Mar 5, 2008 |
| NRC Officer: | Joe O'Hara |
| Last Updated: | Mar 10, 2008 |
| 44037 - NRC Website | |
Unit 3 | |
|---|---|
| Reactor critical | Not Critical |
| Scram | No |
| Before | Cold Shutdown (0 %) |
| After | Cold Shutdown (0 %) |
WEEKMONTHYEARENS 440372008-03-06T02:00:0006 March 2008 02:00:00
[Table view]10 CFR 50.72(b)(3)(ii)(A), Seriously Degraded Circumferential Piping Crack ENS 410692004-09-24T18:00:00024 September 2004 18:00:00 10 CFR 50.72(b)(3)(ii)(A), Seriously Degraded Nureg-1022 Clarification Revised Results of Past Steam Generator Tube Insepctions ENS 410242004-09-08T05:00:0008 September 2004 05:00:00 10 CFR 50.72(b)(3)(ii)(A), Seriously Degraded Potential Reactor Coolant System Pressure Boundary Leak Located ENS 402222003-10-04T14:32:0004 October 2003 14:32:00 10 CFR 50.72(b)(3)(ii)(A), Seriously Degraded Degraded Condition Due to Rcs Pressure Boundary Leakage 2008-03-06T02:00:00 | |