ML13112A225
| ML13112A225 | |
| Person / Time | |
|---|---|
| Site: | Vogtle  |
| Issue date: | 04/25/2013 |
| From: | Martin R Plant Licensing Branch II |
| To: | Ajluni M Southern Nuclear Operating Co |
| Martin R NRR/DORL/LPL2-1 | |
| References | |
| TAC MF0736 | |
| Download: ML13112A225 (4) | |
Text
UNITED STATES NUCLEAR REGULATORY COMMISSION WASHINGTON, D.C. 20555-0001 April 25, 2013 Mr. M. J. Ajluni Nuclear Licensing Director Southern Nuclear Operating Company, Inc.
40 Inverness Center Parkway P. O. Box 1295, Bin -038 Birmingham, AL 35201-1295
SUBJECT:
VOGTLE ELECTRIC GENERATING PLANT, UNIT 2 - CONFERENCE CALLS
SUMMARY
REGARDING THE SPRING 2013 STEAM GENERATOR TUBE INSPECTIONS (TAC NO. MF0736)
On March 18 and 22, 2013, the Nuclear Regulatory Commission (NRC) staff participated in conference calls with representatives of Southern Nuclear Operating Company, Inc. (SNC, the licensee) regarding their ongoing steam generator (SG) tube inspection activities at Vogtle Electric Generating Plant (VEGP) Unit 2 during refueling outage sixteen (RF016). A summary of the conference calls is enclosed. As noted in the enclosure, the staff did not identify any issues that warranted immediate follow-up action.
Sincerely, f2~k1.i~t~ect Manager Plant Licensing Branch 11-1 Division of Operating Reactor Licensing Office of Nuclear Reactor Regulation Docket No. 50-425
Enclosure:
Summary of Conference Calls cc w/encl: Distribution via Listserv
UNITED STATES NUCLEAR REGULATORY COMMISSION OFFICE OF NUCLEAR REACTOR REGULATION
SUMMARY
OF CONFERENCE CALLS WITH VOGTLE ELECTRIC GENERATING PLANT. UNIT 2 REGARDING THE SPRING 2013 STEAM GENERATOR TUBE INSPECTIONS DOCKET NO. 50-425 On March 18 and 22, 2013, the staff of the Steam Generator Tube Integrity and Chemical Engineering Branch (ESGB) of the Division of Engineering participated in conference calls with representatives of Southern Nuclear Operating Company, Inc. (the licensee) regarding their ongoing steam generator (SG) tube inspection activities at Vogtle Electric Generating Plant, Unit 2, during refueling outage sixteen (RF016).
Vogtle Electric Generating Plant, Unit 2, has four Westinghouse Model F SGs, each of which contains 5,626 U-bend thermally treated Alloy 600 tubes. Each tube has a nominal outside diameter of 0.688 inches and a nominal wall thickness of 0.040 inches. During SG fabrication, the tubes were hydraulically expanded, at both ends, over the full depth of the tubesheet.
Type 405 stainless steel support plates, which have broached quatrefoil holes, support the vertical section of the tubes, and anti-vibration bars support the U-bend section of the tubes.
March 18, 2013 call:
The baseline inspection scope for this refueling outage was 100 percent eddy current testing (ET) inspection of the tubes in SG 2 and SG 3. At the time of the conference call, the tube inspections were approximately 96 percent complete in SG 2 and approximately 99 percent complete in SG 3.
During examination of the hot-leg (HL) side of SG 2 at the top-of-the-tubesheet (TIS), an indication of outside diameter stress corrosion cracking (ODSCC) was found in the tube in row 15 column 60 (R15C60), approximately 0.2 inches below the TIS. The indication was located at the bottom of the expansion transition. The indication was found with a +Point' probe and confirmed with a Ghent probe. The indication had a circumferential extent of 46.6 degrees, and maximum depth of 33 percent, and a calculated percent degraded area of 4.5 percent.
Based on the ODSCC indication in SG 2, the licensee was expanding the scope of their ET inspections to perform a 20 percent sample inspection of the TTS on the HL side of both SG 1 and SG 4. At the time of the call, the expanded ET inspections had not yet started. The planned 20 percent sample inspections would be performed from 3 inches above the TIS to 15.2 inches below the TIS. The 15.2-inch measurement is the distance of the approved H*
(H-star) alternate repair criteria, for tube indications within the tubesheet.
Enclosure
- 2 The Nuclear Regulatory Commission (NRC) staff asked to be informed if any additional ODSCC indications were found during the remaining inspections. The licensee indicated that they would schedule a follow-up call with the NRC staff when all inspections of SG 1 and SG 4 were complete.
March 22, 2013, call:
After completion of the SG exams, the licensee confirmed that no additional stress corrosion cracking indications were found. The licensee indicated that the signal-to-noise ratio of the indication in R15C60 of SG 2 was greater than 15:1, that there was no axial component to the indication, and that the tube had been stabilized and plugged.
The NRC staff did not identify any issues that warranted immediate follow-up action.
Principal Contributor: Andrew Johnson
April 25, 2013 Mr. M. J. Ajluni Nuclear Licensing Director Southern Nuclear Operating Company, Inc.
40 Inverness Center Parkway P. O. Box 1295, Bin -038 Birmingham, AL 35201-1295
SUBJECT:
VOGTLE ELECTRIC GENERATING PLANT, UNIT 2 - CONFERENCE CALLS
SUMMARY
REGARDING THE SPRING 2013 STEAM GENERATOR TUBE INSPECTIONS (TAC No. MF0736)
On March 18 and 22,2013, the Nuclear Regulatory Commission (NRC) staff participated in conference calls with representatives of Southern Nuclear Operating Company, Inc. (SNC, the licensee) regarding their ongoing steam generator (SG) tube inspection activities at Vogtle Electric Generating Plant (VEGP) Unit 2 during refueling outage sixteen (RF016). A summary of the conference calls is enclosed. As noted in the enclosure, the staff did not identify any issues that warranted immediate follow-up action.
Sincerely, IRA!
Robert E. Martin, Senior Project Manager Plant Licensing Branch 11-1 Division of Operating Reactor Licensing Office of Nuclear Reactor Regulation Docket No. 50-425
Enclosure:
Summary of Conference Calls cc w/encl: Distribution via Listserv DISTRIBUTION:
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04/25/13 04/25/13 OFFICIAL RECORD COPY