ML091030039
| ML091030039 | |
| Person / Time | |
|---|---|
| Site: | Watts Bar  |
| Issue date: | 04/21/2009 |
| From: | John Lamb Watts Bar Special Projects Branch |
| To: | Swafford P Tennessee Valley Authority |
| Lamb J, NRR/DORL, 415-1727 | |
| References | |
| TAC MD9709 | |
| Download: ML091030039 (3) | |
Text
April 21, 2009 Mr. Preston D. Swafford Chief Nuclear Officer and Executive Vice President Tennessee Valley Authority 3R Lookout Place 1101 Market Street Chattanooga, TN 37402-2801
SUBJECT:
WATTS BAR NUCLEAR PLANT, UNIT 1 - REVIEW OF STEAM GENERATOR TUBE INSPECTION REPORT FOR CYCLE 8 (TAC NO. MD9709)
Dear Mr. Swafford:
By letters dated June 24, 2008 (Agencywide Document and Management System Accession No. ML081840101), September 11, 2008 (ML082600068), and April 3, 2009 (ML090960558),
Tennessee Valley Authority (TVA) submitted information pertaining to the 2008 (Cycle 8) steam generator (SG) tube inspections performed at Watts Bar Nuclear Plant (WBN), Unit 1.
The U.S. Nuclear Regulatory Commission (NRC) staff has reviewed the information that TVA provided and concludes that TVA provided the information required by WBN Unit 1 Technical Specifications and that no additional follow-up is required at this time. The NRC staff review of the SG portions of the reports is enclosed.
If you have any questions regarding this issue, please feel free to contact me at (301) 415-3100.
Sincerely,
/RA/
John G. Lamb, Senior Project Manager Watts Bar Special Projects Branch Division of Operating Reactor Licensing Office of Nuclear Reactor Regulation Docket No. 50-390
Enclosure:
As stated cc w/encl: Distribution via Listserv
Mr. Preston D. Swafford Chief Nuclear Officer and Executive Vice President Tennessee Valley Authority 3R Lookout Place 1101 Market Street Chattanooga, TN 37402-2801
SUBJECT:
WATTS BAR NUCLEAR PLANT, UNIT 1 - REVIEW OF STEAM GENERATOR TUBE INSPECTION REPORT FOR CYCLE 8 (TAC NO. MD9709)
Dear Mr. Swafford:
By letters dated June 24, 2008 (Agencywide Document and Management System Accession No. ML081840101), September 11, 2008 (ML082600068), and April 3, 2009 (ML090960558),
Tennessee Valley Authority (TVA) submitted information pertaining to the 2008 (Cycle 8) steam generator (SG) tube inspections performed at Watts Bar Nuclear Plant (WBN), Unit 1.
The U.S. Nuclear Regulatory Commission (NRC) staff has reviewed the information that TVA provided and concludes that TVA provided the information required by WBN Unit 1 Technical Specifications and that no additional follow-up is required at this time. The NRC staff review of the SG portions of the reports is enclosed.
If you have any questions regarding this issue, please feel free to contact me at (301) 415-3100.
Sincerely,
/RA/
John G. Lamb, Senior Project Manager Watts Bar Special Projects Branch Division of Operating Reactor Licensing Office of Nuclear Reactor Regulation Docket No. 50-390
Enclosure:
As stated cc w/encl: Distribution via Listserv DISTRIBUTION:
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DATE 04 / 21 / 09 04/ 13 /09 04/10/09 04/ 21 /09 OFFICIAL RECORD COPY
Enclosure OFFICE OF NUCLEAR REACTOR REGULATION REVIEW STEAM GENERATOR TUBE INSPECTION REPORT FOR CYCLE 8 WATTS BAR NUCLEAR PLANT, UNIT 1 TENNESSEE VALLEY AUTHORITY DOCKET NO. 50-390 By letters dated June 24, 2008 (Agencywide Document and Management System Accession No. ML081840101), September 11, 2008 (ML082600068), and April 3, 2009 (ML090960558),
Tennessee Valley Authority (TVA) submitted information pertaining to the 2008 (Cycle 8) steam generator (SG) tube inspections performed at Watts Bar Nuclear Plant (WBN), Unit 1.
The four SGs at WBN Unit 1 were replaced in 2006 with SGs designed by Westinghouse and fabricated by Doosan Heavy Industry and Construction. Each SG contains 5128 thermally-treated Alloy 690 tubes. Each tube has a nominal outside diameter of 0.75 inches and a nominal wall thickness of 0.043 inches. The tubes were hydraulically expanded at both ends for the full depth of the tubesheet. The SGs have an integral preheater. The tubes are supported by type 409 stainless steel lattice grids (some of the lattice grids only support a fraction of the tubes).
The tubes installed in rows 1 through 38 were thermally stress relieved over their entire length after bending.
TVA provided the scope, extent, methods, and results of their SG tube inspections in the documents referenced above. In addition, TVA described corrective actions (e.g., tube plugging) taken in response to the inspection findings.
Based on its review of the reports submitted, the U.S. Nuclear Regulatory Commission (NRC) staff has the following observations and comments:
As of the 2008 refueling outage, the SGs had operated for approximately 14.2 effective full power months (EFPM). This was the first inservice inspection of these SGs.
Nine wear indications were detected in six tubes. These indications were at the tube supports and all indications were at cold-leg tube supports. All of the affected tubes were plugged. The maximum depth of the indications was 13 percent through-wall.
Based on a review of the information provided, the NRC staff concludes that TVA provided the information required by WBN Unit 1 technical specifications. In addition, the NRC staff concludes that there are no technical issues that warrant follow-up action at this time since the inspections appear to be consistent with the objective of detecting potential tube degradation and the inspection results appear to be consistent with industry operating experience at similarly designed and operated units.