ML102640440

Steam Generator Tube Inspection Report

ML102640440
Person / Time
Site:	North Anna
Issue date:	09/21/2010
From:	Funderburk C Dominion Resources Services, Virginia Electric & Power Co (VEPCO)
To:	Document Control Desk, Office of Nuclear Reactor Regulation
References
10-519
Download: ML102640440 (7)

Text

Dominion Resources Services, In c.

5000 D om inion Bou levard, Glen Allen, VA 23060 Web Add ress: www.do m.com September 21, 2010 U.S. Nuclear Regulatory Commission Serial No.10-519 Attention: Document Control Desk NL&OS/JHL Washington, D.C. 20555 Docket No. 50-339 License No. NPF-7 VIRGINIA ELECTRIC AND POWER COMPANY (DOMINION)

NORTH ANNA POWER STATION UNIT 2 STEAM GENERATOR TUBE INSPECTION REPORT Pursuant to Technical Specification 5.6.7 for North Anna Power Station Unit 2, Dominion is required to submit a 180-day steam generator tube inspection report. The attachment to this letter provides the steam generator tube inspection report for the North Anna Unit 2 spring 2010 refueling outage.

Should you have any questions or require additional information, please contact Mr.

Thomas Shaub at (804) 273-2763.

Very truly yours, C. L. Funderburk, Director Nuclear Licensing and Operations Support Dominion Resources Se rvices, Inc.

for Virginia Electric and Power Company Attachment Commitments made in this letter: None

Serial No.1 0-519 Docket No. 50-339 180-Day SG Report I Page 2 of 2 cc: U.S. Nuclear Regulatory Commission Region II Marquis One Tower 245 Peachtree Cente r Avenue, NE Suite 1200 Atlanta , Georgia 30303- 1257 Mr. J. E. Reasor , Jr.

Old Dominion Electric Cooperative I

Innsbrook Corporate Center 4201 Dominion Blvd.

S~ite 300 G j~n Allen, Virginia 23060 II NfC Senior Resident Inspector N~lrth Anna Power Station II Ms.

, , K. R. Cotton NRC Project Manager uJ IS . Nuclear Regulatory Commission OHe White Flint North M~i1 Stop 08 G9A 11555 Rockville Pike Rbbkville , Maryland 20852 DrJV. Sreenivas NRC Project Manager u!is. Nuclear Regulatory Commission Ohe White Flint North M~i1 Stop 08 G9A 11555 Rockville Pike Rockville, Maryland 20852

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Serial No.1 0-519 Docket No. 50-339 180-Day SG Report ATTACHMENT NORTH ANNA UNIT 2 180-DAY NRC REPORT REGARDING STEAM GENERATOR TUBE INSPECTION PER TECHNICAL SPECIFICATION 5.6.7 VIRGINIA ELECTRIC AND POWER COMPANY (DOMINION)

II Serial No.10-519 Docket No. 50-339 180-Day SG Report Page 1 of 4 SPRING 2010 - NORTH ANNA UNIT 2 STEAM GENERATOR INSPECTIONS I During the North Anna spring 2010 refueling outage, steam generator inspections were completed in accordance with TS 5.5.8.d for steam generator "B". This was the second inspection I'conducted using Technical Specifications which incorporated TSTF-449.

Transmittal of the following satisfies the North Anna Power Station Technical Specification (TS) reporting requirement section 5.6.7 .

Based on i1nitial entry into Mode 4 on April 23, 2010 , this report is required to be submitted by Octoben 20, 2010. The Effective Full Power Months (EFPM) for the Unit 2 SG's is 157.5.

Italicized wording represents TS verbiage. The required information is provided under each repoting requirement as follows:

A report shall be submitted within 180 days after the initial entry into Mode 4 following completion of an inspection performed in accordance with the Specification 5.5.8, "Steam Generator l(SG) Program." The report shall include:

a. The scbpe of inspections performed on each SG The fOIII~Wing primary side inspec tions were performed in steam generator "B":

• t ideo examination of both channel heads (as-tound / as-left) (there were no previously installed tube plugs in SG "B" and none were installed during the spring I

2010 outage)

• 100% full-leng th inspection utilizing bobbin coil probe for all tubes except for

~ow 1 U-bends

• 26% (928 tubes) hot leg top of tubesheet (+/- 3") utilizing rotating coil probe with t1ube selection biased toward a secondary side critical area in the sludge zone, peripheral area tubes , and the remainder across the tubesheet

• 16% (570 tubes) cold leg top of tubesheet (+/- 3") utilizing rotating coil probe With tube sample const ituting 50% of all tubes within five tubes of the bundle periphery I

• 100% Row 1 (98 tubes) U-bend region utilizing rotating coil probe I

• $pecial interest inspections of dents/dings> 2 volts using a rotating coil probe .

~ S a m p l e size: SG "B" 100% of hot leg indications, 45% all locations)

• II~spection of bobbin identified I-codes (i.e., possible damage indications) with

~otati n g coil probe (Sample size: SG "B" - 0 tests)

• Special interest rotating coil probe exams of largest voltage tubesheet overexpansions (OXP) (Sample size: SG "B" 29 hot leg exams and 21 cold leg I

exams)

• Bounding rotating coil probe examinations of a foreign object (6 examinations performed) .

III Serial No.10-519 Docket No. 50-339 180-Day SG Report Page 2 of4

• ~otating coil probe examinations of all hot leg Historical Manufacturing Brandish Mark indications The fOlllwing seconda ry side inspections were performed in steam generator "B":

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• . Steam drum upper components visual inspect ion covering the primary and s~condary moisture separators , drain piping, and related components

• ~i d e o inspection of the upper tube bundle U-bend area

• 'vjideo inspection of the uppermost tube support plate (TSP) , (i.e. i h TSP) in the periphery area and in-bundle at selected tube columns . The 4th, 5th, and 6th

~S Ps were video inspected in the center bundle area accessed from the i h TSP inspection port.

• Video inspection of the inside interface of the feed ring to J-nozzle joints.

High pressure water lancing was performed in all steam generators with post-lancing top-of-tubesheet video inspections to check for cleanliness and the presence of foreign objects .' A pre-lancing , in-bundle visual exam ination was also performed at the top-of-tubesheet in SG "B". Sludge lancing operations removed 18 pounds of sludge from SG "A", 18 pounds of sludge from SG "B" and 11.5 pounds of sludge from SG "C",

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During the post-sludge lancing, top of tubesheet visual examination of SG "A", a 0.06 inch diameter by 1 inch metallic object was identified and removed from the annulus near R1OC2 on the cold leg side on the top of the tube sheet. The object appeared to be a srriall brad. The object was not lodged and was likely moved to as-found location during sludge lancing operations. Close visual examination of the as-found location revealed no evidence of tube degradation. Due to its small size and mass it is considered very unlikely to have caused tube degradation elsewhere.

I During the post-sludge lancing, top of tubesheet visual examination of SG "B", a wire sized I~ss than 0.020 inch in diameter by less than 0.5 inch in length, was identified.

The object was embedded in hard sludge collar material between tubes R4C50 and R4C51 on the hot leg side on the top of the tube sheet. The exposed portion of the wire br6ke free and was dropped during retrieval. Further attempts to retrieve the freed fragment were unsuccessful and were discontinued. Due to the small diameter, length, and mi ~imal mass, it was concluded that this object posed no threat to tube integrity.

During the post-sludge lancing , top of tubesheet visual examination of SG "C", a 0.2 inch by 10.5 inch by 0.75 inch metallic object was identified and removed from between R41C29, R42C29, and R42C28 of the hot leg side on the top of the tube sheet. The object appeared to be a small agglomeration of weld slag. The tubes in the vicinity of and adjacent to the object were closely examined visually. Only surface discoloration was observed with no evidence of tube degradation , providing reasonable assurance of structur~1 integrity.

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I I Serial NO.1 0-519 Docket No. 50-339 180-Day SG Report Page 3 of 4

b. Active degradation mechanisms found I

No indications of tube degradation were identified during the spring 2010 SG examinations of "8" SG. In addition, the secondary side visual inspections performed on all three SGs identified no component degradation that could compromise tube integrity.

c. Nondestructive examination techniques utilized for each degradation mechanism Inspections focused on the following degradation mechanisms listed in Table 1 utilizing the refe'renced eddy current techniques.

I Table 1 - Inspection Method for Applicable Degradation Modes Classification Degradation Location Probe Type Mechanism I

Bobbin - Detection Potential Tube Wear Anti-Vibration Bars Bobbin and +Point' - SiZing I

I Flow Distribution Bobbin - Detection Potential Tube Wear Baffle Bobbin and +Point' - Sizing Bobbin - Detection Existing Tube Wear Tube Support Plate Bobbin and +Point' - Sizing Straight Leg & AVB Potential Bobbin - Detection Tube Wear Tangents (Row 8, Bobbin or +Point' - Sizing 14,26)

Tube Wear Bobbin and +Point' - Detection Potential Freespan and TTS I

(foreign objects) +Point' - Sizing I Hot Leg Top-of-Bobbin and +Point' - Detection Potential ODSCC Tubesheet Sludge

+Point' - Sizing Pile Area Top-of-Tubesheet Bobbin - Detection Potential OD Pitting Sludge Pile Area +Point' - Sizing Hot Leg Top-of-Relevant/ Tubesheet Sludge Informational PWSCC Pile Area and +Point' - Detection and Sizing Inspection Within Tubesheet I Anomaly locations I . ODSCC Relevant/I nformational Row 1 U-bends +Point' - Detection and Sizing Inspection PWSCC Freespan and Tube Relevant/Informational Supports ; TTS Inspection ODSCC +Point' - Detection and Sizing outside the critical area

Serial NO.1 0-519 Docket No. 50-339 180-Day SG Report Page 4 of4

d. Location, orientation (if linear) , and measured sizes (if available) of service induced indications No tube wall degradation was detected during the eddy current examinations of SG "B".

e. Number of tubes plugged during the inspection outage for each active degradation mechanism No tubes were plugged during this inspection .

t. Total number and percentage of tubes plugged to date A total of six (6) tubes have been plugged in the North Anna Unit 2 steam generators, i.e. "A" - 1 (0.03%) , "B" - 0 (0%), "C" - 5 (0.14%) with an overall percentage of 0.056%.

g. The results of condition monitoring, including the results of tube pulls and in-situ testing The Condition Monitoring Assessment concluded that steam generator "B" did not exceed any performance criteria during the period since the fall 2005 inspection. No findings from the spring 2010 inspection invalidated the previous operational assessment for any of the three steam generators and the condit ion monitoring requirements were met. Therefore, tube pulls and in-situ pressure testing were not necessary.

h. The effective plugging percentage for all plugging in each SG There are no sleeves installed in the North Anna Unit 2 steam generators therefore, the effective plugging percentage remains the same as stated in (f) above.