NL-12-1561, Response to Request for Additional Information Regarding the 2011 Steam Generator Tube Inspection Summary

Response to Request for Additional Information Regarding the 2011 Steam Generator Tube Inspection Summary

ML12212A335
Person / Time
Site:	Vogtle
Issue date:	07/30/2012
From:	Ajluni M Southern Nuclear Operating Co, Southern Co
To:	Document Control Desk, Office of Nuclear Reactor Regulation
References
NL-12-1561
Download: ML12212A335 (5)

Text

Mark J. Ajluni. P.E. Southern Nuclear Nuclear Licensing Director Operating Company. Inc.

40 Inverness Center Parkway Post Office Box 1295 Birmingham. Alabama 35201 Tel 205.992.7673 Fax 205992.7885 July 30, 2012 SOUTHERN . \

COMPANY Docket Nos.: 50-424 NL-12-1561 U. S. Nuclear Regulatory Commission ATIN: Document Control Desk Washington, D. C. 20555-0001 Vogtle Electric Generating Plant - Unit 1 Response to Request for Additional Information Regarding the 2011 Steam Generator Tube Inspection Summary Ladies and Gentlemen:

By letters dated June 30, 2011 (Agencywide Documents Access and Management System (ADAMS), Accession Number ML111820361) and September 21, 2011 (ADAMS Accession No. ML112650199), Southern Nuclear Operating Company (SNC) submitted information summarizing the results of the 2011 steam generator tube inspection performed at Vogtle Electric Generating Plant (VEGP), Unit 1 during refueling outage 16. On July 5,2012, the Nuclear Regulatory Commission (NRC) provided SNC with a Request for Additional Information (RAI) letter (ADAMS Accession No. ML12185A095), which contained 3 questions regarding the Vogtle 1R16 Steam Generator Inspection Report. contains the SNC response to the NRC questions from the July 5, 2012 letter.

This letter contains no NRC commitments. If you have any questions, please contact Lesa Hill at (205) 992-5727.

Respectfully submitted, M. J. Ajluni Nuclear Licensing Director MJAlRMJllac

Enclosure:

Response to Request to Additional Information Regarding the 2011 Steam Generator Tube Inspection Summary

U. S. Nuclear Regulatory Commission NL-12-1561 Page 2 cc: Southern Nuclear Operating Company Mr. S. E. Kuczynski, Chairman, President & CEO Mr. D. G. Bost, Executive Vice President & Chief Nuclear Officer Mr. T. E. Tynan, Vice President - Vogtle Mr. B. L. Ivey, Vice President - Regulatory Affairs Mr. B. J. Adams, Vice President - Fleet Operations RType: CVC7000 U. S. Nuclear Regulatory Commission Mr. V. M. McCree, Regional Administrator Mr. P. G. Boyle, NRR Senior Project Manager - Vogtle Mr. L. M. Cain, Senior Resident Inspector - Vogtle

Vogtle Electric Generating Plant - Unit 1 Enclosure Response to Request to Additional Information Regarding the 2011 Steam Generator Tube Inspection Summary

Enclosure to NL-12-1561 Response to Request to Additional Information Regarding the 2011 Steam Generator Tube Inspection Summary NRC Question 1 Please discuss the scope and results of your secondary side inspections, if any. Was there any evidence of change in the region of SG 4 affected by the tube pulling operation?

SNC Response Secondary side maintenance and inspection activities performed during Vogtle Unit 1 refueling outage 16 in Spring 2011 included top of tubesheet (TTS) sludge lance and foreign object search and retrieval (FOSAR) of all four steam generators. FOSAR inspections included the following regions:

• Annulus and tubelane region including periphery tubes

• Historical foreign opjects identified in previous inspections

• Possible loose parts (PLPs) from eddy current tube inspections Sludge lancing removed a total of 23.5 pounds of material from all four steam generators.

After FOSAR, 44 objects remained in the steam generators. Seven of these remaining objects were metallic and 37 objects were sludge rocks. All the metallic objects remaining in the steam generators were classified as Category 3 and are not expected to cause significant tube wear over long term operation. This classification is taken from EPRI Report Number 1019039, "Steam Generator Management Program: Foreign Object Prioritization Strategy for Square Pitch Steam Generators," May 2009.

There was no evidence of change in the region of SG 4 affected by the tube pulling operation based on the eddy current bobbin probe data.

NRC Question 2 On page E-2 wear due to foreign objects was observed in al/ SGs. However, in Table 1, there does not appear to be any wear attributed to foreign objects on SG 2. Please clarify.

SNC Response Page E-2 incorrectly states wear attributed to foreign objects was found in all SGs. Mechanical wear due to foreign objects was discovered during 1R16 for SGs 1, 3, and 4. No wear attributable to foreign objects was identified in SG 2 during 1R16.

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Enclosure to NL-12-1561 Response to Request to Additional Information Regarding the 2011 Steam Generator Tube Inspection Summary NRC Question 3:

Please discuss whether any foreign objects/loose parts remain in the 5Gs.

If so, discuss whether an analysis was performed to assess their affect on tube integrity until the next inspection. Were any foreign objects/loose parts left near active tubes with wear indications attributed to those loose parts?

SNC Response:

After FOSAR, 44 objects remained in the steam generators. Seven of these remaining objects were metallic and 37 objects were sludge rocks. An engineering evaluation of these objects shows the limiting objects have a wear time greater than three effective full power years (EFPY) or two operational cycles without exceeding steam generator performance criteria. There were no new wear indications identified during 1R16 at the TIS in any tube adjacent to these foreign objects.

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