ML19179A075

Steam Generator Tube Inspection Report

ML19179A075
Person / Time
Site:	North Anna
Issue date:	06/24/2019
From:	Lane N Virginia Electric & Power Co (VEPCO)
To:	Document Control Desk, Office of Nuclear Reactor Regulation
References
19-290
Download: ML19179A075 (7)

Text

VIRGINIA ELECTRIC AND POWER COMPANY

.\ *_*.(* : .

RICHMOND, VIRGINIA 2~261 June 24, 2019 U.S. Nuclear Regulatory Commission Serial No.19-290 Attention: Document Control Desk NAPS/DPM RO Washington, D.C. 20555 Docket No. 50-339 License No. NPF-7 VIRGINIA ELECTRIC AND POWER COMPANY (DOMINION)

NORTH ANNA POWER STATION UNIT2 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 2019 outage.

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

Daniel P. McGinnis at (540) 894-2487.

Very truly yours, N. Larry Lane Site Vice President Attachment Commitments made in this letter: None

cc: U.S. Nuclear Regulatory Commission Region II Marquis One Tower 245 Peachtree Center Avenue, NE Suite 1200 Atlanta, Georgia 30303-1257 Mr. G. E. Miller NRC Project Manager - North Anna U. S. Nuclear Regulatory Commission One White Flint North Mail Stop 08 B-1A 11555 Rockville Pike Rockville, Maryland 20852-2738 Ms. K. R. Cotton NRC Project Manager U.S. Nuclear Regulatory Commission One White Flint North Mail Stop 08 G-9A 11555 Rockville Pike Rockville, Maryland 20852-2738 NRC Senior Resident Inspector North Anna Power Station 2

. \

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)

• l SPRING 2019- NORTH ANNA UNIT 2 STEAMJ3ENERATOR INSPECTIONS The following satisfies the North Anna Power Station Technical Specification (TS) reporting requirement section 5.6.7. During the North Anna Unit 2, spring 2019 refueling outage, steam generator (SG) inspections in accordance with TS 5.5.8.d were completed for all three steam generators ("A", "B" and "C").

The Unit 2 Steam Generators have accrued 22.1 Effective Full Power Years (EFPY) of operation as of the end of Cycle 26 (March, 2019).

Initial entry into Mode 4 occurred on April 7, 2019 (0135 Hrs); therefore, this report is required to be submitted by October 4, 2019.

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 each steam generator:

• Visual examination of both channel heads (as..:found / as-left) specifically including:

o all plugs o the divider plate weld region o the bottom of the bowl per NSAL-12-1 and NRC IN 2013-20 with the bowl dry

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

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

• 29% of h.ot 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

• Special interest inspections of dents/dings with rotating coil probe (Sample: 100%

of dents/ding ~ 5 Volts) *

• Augmented sample inspections were perfc;>rmed in areas of special interest including hot leg expansion transitions, tube overexpansion locations. Results identified in Table 1 below.

' ,

• I Table 1 - Bobbin Probe Indication / Special Interest Exam Summary KEY: tubes / indications /

SG"A" SG "B" SG "C" indications tested with +Point TSP Wear 0/0/0 5/7/7 4/5/5 Dents ~5 Volts 2/2/2 ,,

2/2/2 1/ 1/ 1 Hot Leg MBH 14 / 14 / 14 18/19/19 11/11/11 Hot Leg OXP 353 / 451 / 36 323 / 445 / 20 503 / 790 / 23

'(.

Cold Leg OXP 149 / 170 / 4 ' 490 /657 / 8 605 / 1002 / 4 OVR 5/5/5 0/0/0 2/2/2 NTE 0/0/0 4/4/4 2/2/2 The following secondary side inspections were performed in each steam generator:

• 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 AVB supports.

• Visual inspections of J-nozzle to feedring internal interface for flow assisted corrosion in the carbon steel portions of the feed rings.

• Visual inspections of upper tube support plates via ]1h TSP handholes to assess structural condition and cleanliness, including that of TSP wedges and associated welds.

• Ultrasonic thickness measurement of selected feed ring locations.

The results of all secondary-side visual examinations performed were satisfactory.

b. Degradation mechanisms found Tube Support Plate (TSP) wear was the only tube degradation mechanism reported during this inspection.

c. Nondestructive examination techniques utilized for each degradation mechanism Table 2 identifies the examination technique used for the identified degradation mechanism.

Table 2 - Degradation Mechanisms and Inspection Techniques Degradation Classification Location Probe Type Mechanism Detection - Bobbin Existing Wear Tube Support Plate (TSP)

Sizing - +Point'

d. Location, orientation (if linear), and measured sizes . (if available) of service induced indications As stated in the (b) response above, service induced indications were identified. Table 3 below provides the required information.

Table 3 - Tube Degradation Summary Max In-Situ Plugging SG Row Col Location ETSS Depth Testing Required?

(%TW) Required?

A No degradation detected during 2R26 03C -0.75 B 1 19 96910.1 12 No No to +0.18 03C-0.71 96910.1 8 No No to -0.17 05C -0.82 B 2 56 96910.1 9 No No to -0.32 05C-0.80 96910.1 8 No No to -0.27 05C-0.84 B 2 58 96910.1 6 No No to -0.41 05C-0.43 B 3 15 96910.1 12 No No to +0.33 05C-0.88 B 22 86 96910.1 8 No No to -0.44 C 2 13 02C -0.31 96910.1 8 No No C 2 93 03C +0.43 96910.1 5 No No

.. * ' .I 05C -0.60 96910.1 5 No No C 7 97 05C +0.34 96910.1 9 No No C 9 97 05C -0.61 96910.1 6 No No

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 4 summarizes the current tube plugging status for North Anna Unit 2 steam generators.

Table 4 - Current Tube Plugging Status

... . ,.N.u.mb.er.of. :_: .

Steam-G~nerat6r

• - . .*:1 - * * - - .

• * . Phigge.c;I T~be$ . .,._

_ P~r~ent P.iug.ged)'*:<

,. * . , : . :, ***.L ~-

A 1 0.03%

8 0 0.00%

C 7 0.19%

Total 8 0.07%

Since no sleeving has been performed in the North Anna Unit 2 SGs, the effective plugging percentage is the same as the actual plugging percentage.

g. The results of condition monitoring, including the results of tube pulls and in-situ testing No tubes were pulled and no in-situ pressure tests were performed. The condition monitoring assessment concluded that the structural integrity, operational leakage, and accident-induced leakage performance criteria were not exceeded during the operating interval preceding 2R26.