NL-08-1233, Response to Request for Additional Information Regarding the Steam Generator Tube Inservice Inspection Report for Refueling Outage 18

Response to Request for Additional Information Regarding the Steam Generator Tube Inservice Inspection Report for Refueling Outage 18

ML082320487
Person / Time
Site:	Farley
Issue date:	08/18/2008
From:	Ajluni M Southern Nuclear Operating Co
To:	Document Control Desk, Office of Nuclear Reactor Regulation
References
NL-08-1233
Download: ML082320487 (6)

Text

Southern Nuclear Operating Company, Inc.

Post Office Box 1295 Birmingham, Alabama 35201-1295 Tel 205.992.5000 SOUTHERN . \

COMPANY August 18, 2008 Energy to Serve Your World'"

Docket Nos.: 50-364 NL-08-1233 U. S. Nuclear Regulatory Commission ATIN: Document Control Desk Washington, D. C. 20555-0001 Joseph M. Farley Nuclear Plant - Unit 2 Response to Request for Additional Information Regarding the Steam Generator Tube Inservice Inspection Report for Refueling Outage 18 Ladies and Gentlemen:

In letter dated November 1,2007, Southern Nuclear Company (SNC) submitted information summarizing the results of the 2007 steam generator (SG) tube inspections performed at Joseph M. Farley Nudear Plant Unit 2 during refueling outage 18.

On July 1, 2008, a NRC Request for Additional Information (RAI) was received regarding information needed for the staff to complete review. The SHC response to the requested information is provided in the Endosure.

This letter contains no NRC commitments. If you have any questions, please advise.

Sincerely, M. J. Ajluni Manager, Nuclear Licensing MJAlJLS/phr

U. S. Nuclear Regulatory Commission NL-08-1233 Page 2

Enclosure:

Response to Request for Additional Information Regarding the Steam Generator Tube Inservice Inspection Report for Refueling Outage 18 cc: Southern Nuclear Operating Company Mr. J. T. Gasser, Executive Vice President Mr. J. R. Johnson, Vice President - Farley Mr. D. H. Jones, Vice President - Engineering RTYPE: CFA04.054; LC# 14816 U. S. Nuclear Regulatory Commission Mr. L. A. Reyes, Regional Administrator Mr. R. A. Jervey, NRR Project Manager - Farley Mr. E. L. Crowe, Senior Resident Inspector - Farley

Joseph M. Farley Nuclear Plant - Unit 2 Enclosure Response to Request for Additional Information Regarding the Steam Generator Tube Inservice Inspection Report for Refueling Outage 18

Enclosure Response to Request for Additional Information Regarding the Steam Generator Tube Inservice Inspection Report for Refueling Outage 18 NRC Question 1

1. Regarding the scope of your inspection, please clarify the following:

a) Please discuss the nature of the tubes that "could not be examined full length."

b) It was indicated that 1 dent or ding in SG C had a bobbin voltage greater than or equal to 5 volts. Discuss whether the size of this indication has changed with time (or any other dent or ding indication). If so, please discuss the nature/reason for the change. Please refer to your letter dated December 17, 2004 (ADAMS Accession No. ML043570226).

c) Please discuss how many tubes have non-quantifiable signals and the nature of these indications. In addition, discuss the nature of the "history based indications." Are these indications manufacturing related (since no service induced indications have been reported)?

d) Please discuss the scope and results of any secondary side inspections. If any foreign objects were found during these inspections, discuss how they were detected (bobbin, rotating probe, visual) and whether they were removed from the steam generator. If the objects were not removed, please discuss whether an analysis was performed to ensure tube integrity would not be compromised for the period of time between planned inspections.

SNC Response to NRC Question 1 1.a) Low Row Tubes (Rows 1 and 2) can not be examined full length with the "Bobbin Probe" due to the tight radius of the U-Bends. Inspection of these locations were performed using a "+ Point" probe.

1.b) The size of the referenced SG C indication, has not changed with time. A review of SNC letter dated December 17, 2004 revealed that all Dent and Dings (DNGs) discovered in SG C were inadvertently discussed as less than 5 volts, but actually the referenced SG C indication was greater than 5 volts. Therefore, the 2R18 inspection plan included the 2R15 DNG in SG C which was greater than 5 volts. The 2R18 inspection results determined that the referenced SG C signal was from the U-Bend transition and was not aDNG.

1.c) There were two non-quantifiable signals (NQS) reported from the 2R15 inspection results. These signals are deemed to be manufacturing indications from the single step pilgering process.

The term "history based indications" was used in the section for those inspections that are to be performed by the Bobbin probe. The "history Page 1 of 3

Enclosure Response to Request for Additional Information Regarding the Steam Generator Tube Inservice Inspection Report for Refueling Outage 18 based indications" inspected were the 2R15 dents and dings and the non quantifiable signals listed in this section.

1.d) Inspections I Results Secondary side inspections in all three SGs included:

• Foreign Object Search and Retrieval (FOSAR) -Inspection to search for and remove foreign objects from the tube bundle, annulus and tube lane. For inspection results - see "Foreign Objects Discovered in SGs" below.

• 100% Top of Tubesheet (TIS) In-Bundle - A column-by-column visual examination of the TIS region to search and remove foreign objects.

For inspection results - see "Foreign Objects Discovered in SGs" below.

• Shell Wrapper Annulus Transport System (SWATS) - Annulus inspection performed from the wrapper looking inward toward the tube region. Inspection results were acceptable.

• Wrapper Drop - Inspection to verify access to the tubelane without interference. Inspection results were acceptable.

• Upper Internals - Visual inspection performed in each SG's steam drum of the feedring assembly, support brackets and welds, primary separators, steam outlet nozzle flow limiter, and sludge collector. For inspection results - see "Foreign Objects Discovered in SGs" below.

Additional secondary side inspections performed for SG A:

• Tube Support Plate Ligament Erosion-Corrosion and Cracking: Upper Bundle In-Bundle (USIB) to provide surveillance information on support plate ligaments, quatrefoil blockage, and appearance of upper tube support plates. The 7th tube support plate was also visually inspected from an upper handhole. Inspection results were acceptable.

Foreign Objects Discovered in SGs A number of small objects were observed at the top of the tubesheet within the tube bundle, for example - fragments of spiral wound gaskets, machining remnants, wire bristles, weld slag, pieces of tube scale, and sludge rocks. Approximately 272 objects were found in all three SGs (TIS - 87, Sludge Lance Filter -124, Feedrings - 61), approximately 238 objects were removed. After the extensive retrieval effort, approximately 34 objects remain in the SGs, due to the objects being locked in hard sludge. These objects are being tracked in the plants Page 2 of 3

Enclosure Response to Request for Additional Information Regarding the Steam Generator Tube Inservice Inspection Report for Refueling Outage 18 corrective action program. Wear assessments were performed on the objects remaining in the SG. The SG tube inspection results and analysis of the potential for the remaining foreign objects to cause tube degradation, gives assurance that tube integrity will be maintained until the next scheduled eddy current inspection during 2R21.

NRC Question 2 For each refueling outage and SG tube inspection outage since replacement of your SGs, please provide the cumulative effective full power months (EFPM) that the SGs have operated.

SNC Response to NRC Question 2

• 2R14 - SG Replacement

• 2R15 - First lSI after replacement (approximately 16.2 EFPM)

• 2R18 - Second ISI- (approximately 67.0 EFPM since replacement)

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