ML15050A040

Steam Generator Tube Inspection Report

ML15050A040
Person / Time
Site:	North Anna
Issue date:	02/11/2015
From:	Gerald Bichof Virginia Electric & Power Co (VEPCO)
To:	Document Control Desk, Office of Nuclear Reactor Regulation
References
15-056
Download: ML15050A040 (9)

Text

VIRGINIA ELECTRIC AND POWER COMPANY RICHMOND, VIRGINIA 23261 February 11, 2015 U.S. Nuclear Regulatory Commission Serial No.15-056 Attention: Document Control Desk NAPS/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 fall 2014 outage.

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

Page Kemp at (540) 894-2295.

Very truly yours, Gerald T. BischoW Site Vice President Attachment Commitments made in this letter: None AOC)l

Serial No.15-056 Docket No. 50-339 180-Day SG Report Page 2 of 2 cc: U.S. Nuclear Regulatory Commission Region II Marquis One Tower 245 Peachtree Center Avenue, NE Suite 1200 Atlanta, Georgia 30303-1257 NRC Senior Resident Inspector North Anna Power Station Dr. V. Sreenivas NRC Project Manager U. S. Nuclear Regulatory Commission One White Flint North Mail Stop 08 G9A 11555 Rockville Pike Rockville, Maryland 20852

Serial No.15-056 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)

Serial No.15-056 Docket No. 50-339 180-Day SG Report FALL 2014 - NORTH ANNA UNIT 2 STEAM GENERATOR INSPECTIONS During the North Anna Unit 2 fall 2014 refueling outage, steam generator (SG) inspections were completed in accordance with Technical Specification (TS) 5.5.8.d for SG "B".

Transmittal of this report satisfies the reporting requirement specified in TS 5.6.7.

The Unit 2 Steam Generators have accrued 17.0 Effective Full Power Years (EFPY) of operation as of the end of Cycle 23 (September, 2014).

Initial entry into Mode 4 occurred on October 8, 2014 (1458 hours0.0169 days <br />0.405 hours <br />0.00241 weeks <br />5.54769e-4 months <br />); therefore, this report is required to be submitted by April 6, 2015.

Italicized wording represents TS verbiage. The required information is provided under each reporting 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(SG) Program." The report shall include:

a. The scope of inspections performed on each SG The following primary side inspections were performed in SG "B":

0 Video examination of both channel heads (as-found I as-left).

& 100% full-length inspection utilizing bobbin coil probe for all tubes except for Row 1 U-bends

• 28% of hot leg top of tubesheet (+/-3") utilizing rotating coil probe with tube selection including 50% of the secondary side critical area in the sludge zone, 50% of all tubes within five tubes of the bundle periphery, and other randomly sampled locations

• 17% of cold leg top of tubesheet (+/-3") utilizing rotating coil probe with tube sample constituting 56% of all tubes within five tubes of the bundle periphery

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

• Special interest inspections of dents/dings with rotating coil probe (Sample: 100% of dents/dings > 5 Volts; all new dents)

• Special interest rotating coil probe exams of largest voltage tubesheet over-expansions (OXP) (20 hot leg and 4 cold leg tests) 0 Inspection of all bobbin coil I-codes (i.e., possible indications) with rotating coil probe. Results identified in Table 1 below.

Serial No.15-056 Docket No. 50-339 180-Day SG Report Table 1 - Bobbin Probe Indication / Special Interest Exam Summary KEY: tubes I indications /

indications tested with SG "B"

+Point I-Codes 6/6/6 New Dent 1/ 1/ 1 Dents ->5 Volts** 2/2/2 Hot Leg Straight Dent 12 / 12 / 0 U-bend Dent 7/ 8/ 1 Cold Leg Straight Dent 9/ 9/ 1 Hot Leg Straight Manufacturing Burnish 19 / 20/20 Mark (MBH)

U-bend MBH 2/2/0 Cold Leg Straight MBH 14 / 14 / 0 Historical Hot Leg OXP 323 / 445 /20 Historical Cold Leg OXP 490 / 657 /4 No Tube Expansion 4/4/4 (all are on cold leg)

• • Included in the dent totals The following secondary side inspections were performed in steam generator "B":

" Steam drum visual inspections to evaluate the cleanliness and structural condition of all accessible subcomponents including moisture separators, drain systems, and interior surfaces.

" Drop down examinations through the primary separators to assess the cleanliness and structural condition of the upper tube bundle and anti-vibration bar (AVB) supports.

• Visual inspections of J-nozzle to feedring internal interface for flow assisted corrosion in the carbon steel portions of the tee and inlet sections.

" Visual inspections of upper tube support plates via 7 th tube support plate (TSP) handholes to assess structural condition and cleanliness, including that of TSP wedges and associated welds.

" Ultrasonic thickness measurement of selected feedring locations.

b. Degradationmechanisms found No tube degradation was identified during this examination.

c. Nondestructive examination techniques utilized for each degradationmechanism The 2014 tube inspections focused on the degradation mechanisms listed in Table 2 utilizing the referenced eddy current techniques.

Serial No.15-056 Docket No. 50-339 180-Day SG Report Table 2 - Inspection Method for Applicable Degradation Modes Degradation Classification Mechanism Location Probe Type Bobbin - Detection Potential Tube Wear Anti-Vibration Bars (AVB) Bobbin and +PointTM - Sizing Flow Distribution Baffle Bobbin - Detection Potential Tube Wear (FDB) Bobbin and +PointTM- Sizing Tube Support Plate Bobbin - Detection Existing Tube Wear (TSP) Bobbin and +PointTM - Sizing Potential Tube Wear Freespan & AVB Bobbin - Detection PotntalTue _ea tangents (Row 8, 14, 26) Bobbin or +PointTM- Sizing Tube Wear Freespan, Top-of- Bobbin and +PointmM-Potential (foreign objects) Tubesheet (TTS), FDB, Detection and TSP +PointTM - Sizing Bobbin and +PointTM-Potential IGA/ODSCC Hot Leg TTS sludge pile Detection critical area +PointTM - Sizing Potential OD Pitting TTS sludge pile Bobbin - Detection PotentialODPitting critical area +PointTM - Sizing Hot leg TTS sludge pile Relevant/Informational critical area and +PointTM - Detection and Inspection within-tubesheet Sizing anomaly locations Relevant/Informational IGA/ODSCC Row 1 U-bends +PointTM -SznDetection and Inspection PWSCC Sizing Relevant/Informational Freespan, Bobbin - Detection Inspection IGAIODSCC FDB, TSP +PointTM - Sizing Relevant/Informational TTS outside the +PointTM - Detection and Inspection critical area Sizing

d. Location, orientation (if linear), and measured sizes (if available) of service induced indications No service induced tube indications were identified during the fall 2014 examination.

UT thickness measurements were taken in selected regions of the SG "B" feedring during the outage and identified localized exterior erosion on the side of the feedring Thermal Sleeve below the discharge of nozzle #35, with a minimum measured wall thickness of 0.291". The localized erosion has been evaluated and determined to be acceptable for continued operation until the next scheduled refueling outage in the spring of 2016.

Serial No.15-056 Docket No. 50-339 180-Day SG Report

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

f The number and percentage of tubes plugged to date, and the effective plugging percentage in each steam generator, Table 3 summarizes the current tube plugging status for North Anna Unit 2 steam generators.

Table 3 - Current Tube Plugging Status Number of Plugged Steam Generator Tubes Percent Plugged A 1 0.03%

B 0 0.00%

C 5 0.14%

Total 6 0.06%

g. The results of condition monitoring, including the results of tube pulls and in-situ testing The Condition Monitoring Assessment concluded that SG "B" did not exceed any performance criteria during the period preceding the fall 2014 inspection. No findings from the fall 2014 inspection invalidated previous operational assessments for any of the three steam generators and the condition monitoring requirements were met. Therefore, tube pulls and in-situ pressure testing were not necessary.

The fall 2014 inspection was the first inspection of the Unit 2 SG "B" following the August 2011 earthquake. It was concluded in the inspection results in 2011 of steam generators "A" and "C" that there was no evidence of earthquake-related damage. In the absence of any degradation reported following the current outage primary side and secondary side examinations, the North Anna Unit 2 steam generators continue to satisfy the structural and leakage integrity requirements delineated in the Dominion Steam Generator Program and North Anna Technical Specifications.

Serial No.15-056 Docket No. 50-339 180-Day SG Report Page 1 of 2 bc: (*paper copy; remainder electronic distribution)

Ms. L. Hilbert- NAPS Mr. D. C. Lawrence- SPS Mr. L. J. Armstrong - MPS Mr. J. T. Stafford - KPS Mr. P. A. Kemp - NAPS Mr. R. P. Repshas - KPS Mr. B. A. Garber- SPS Mr. W. D. Bartron - MPS Mr. D. A. Sommers - IN2SE Mr. E. T. Shaub - IN2SE*

Mr. J. H. Leberstien - NAPS Mr. B, Derreberry - NAPS Mr. H. A. Tessier - NAPS Mr. T, M. Mayer - SPS Mr. H. V. Le - NAPS Licensing File*

MSRC Coordinator - IN2SE Records Management - (bc original) - IN-GW*

CONCURRENCE H. A. Tessier /

B. W. Derreberry ,., 4-'

H.V. Le _

P. A. Kemp L. Hilbert

Serial No.15-056 Docket No. 50-339 180-Day SG Report Page 2 of 2 Commitments (Stated or Implied)

1. None Verification of Accuracy

1. E-mail from Harry A. Tessier to Jay Leberstien dated February 3, 2015 entitled North Anna Unit 2 180 Day Report

2. Initial entry into Mode 4 occurred on October 8, 2014 (1458 hours0.0169 days <br />0.405 hours <br />0.00241 weeks <br />5.54769e-4 months <br />); submit by April 6,2015.

Required Changes to the UFSAR or the Topical Report:

1. None Action PlanlCommitments (Stated or Implied):

1. None