ENS Event | |
|---|---|
04:00 Feb 21, 2012 | |
| Title | Part 21 Interim Report - Steam Generator Tube Wear |
| Event Description | This interim Part 21 is in regard to San Onofre Nuclear Generating Station, Unit 2, Steam Generator replacement.
During the first refueling outage following steam generator replacement, eddy current testing identified ten total tubes with depths of 90 to 28 percent of the tube wall thickness. Some of the affected tubes were located adjacent to retainer bars. The retainer bars are part of the floating anti-vibration bar (AVB) structure that stabilizes the u-bend region of the tubes. Other tubes in the two steam generators had detectable wear associated with support points elsewhere in the AVB structure. Each steam generator has 9727 tubes with an 8 percent (778 tubes) design margin for tube plugging. Discovery Date: February 13, 2012 Evaluation completion schedule date: May 31, 2012 Those Mitsubishi Heavy Industries customers potentially affected by this issue have been notified and will receive a copy of this interim report. Reference Document: UET-20120089 Interim Report No: U21-018-IR (0) Notified R1DO (Joustra), R2DO (Nease), R3DO (Peterson), R4DO (O'Keefe), and Part 21 Group via email.
The vendor changed the number of tubes identified with wear depths of 90 to 28 percent from ten tubes to six tubes and only some of the tubes were adjacent to retainer bars. Notified R1DO (Cahill), R2DO (Vias), R3DO (Passehl), R4DO (Gepford) and Part 21 Groups via email.
MHI evaluated that the deviation contains a reportable defect for San Onofre Nuclear Generating Station Unit 2 and 3. Notified R4DO (Gaddy) and Part 21 Reactor Group via email. |
| Where | |
|---|---|
| Mitsubishi Heavy Industries, Ltd Arlington, Virginia (NRC Region 1) | |
| Organization: | Mitsubishi Heavy Industries, Ltd. |
| Reporting | |
| 10 CFR 21.21(a)(2), Interim Report for Comply or Defect in Component | |
| Time - Person (Reporting Time:+1260.97 h52.54 days <br />7.506 weeks <br />1.727 months <br />) | |
| Opened: | Ei Kadokami 15:58 Apr 13, 2012 |
| NRC Officer: | John Knoke |
| Last Updated: | Sep 7, 2012 |
| 47833 - NRC Website | |
Mitsubishi Heavy Industries, Ltd with 10 CFR 21.21(a)(2), Interim Report for Comply or Defect in Component | |
WEEKMONTHYEARENS 478332012-02-21T04:00:00021 February 2012 04:00:00
[Table view]10 CFR 21.21(a)(2), Interim Report for Comply or Defect in Component Part 21 Interim Report - Steam Generator Tube Wear 2012-02-21T04:00:00 | |