ML21036A077

Review of Steam Generator Tube Inspection Report for the Cycle 26 Spring 2019 Refueling Outage

ML21036A077
Person / Time
Site:	North Anna
Issue date:	02/23/2021
From:	Geoffrey Miller Plant Licensing Branch II
To:	Stoddard D Southern Nuclear Operating Co
Miller G
References
EPID L-2019-LRO-0108
Download: ML21036A077 (3)

Text

February 23, 2021 Mr. Daniel G. Stoddard Senior Vice President and Chief Nuclear Officer Innsbrook Technical Center 5000 Dominion Blvd.

Glen Allen, VA 23060-6711

SUBJECT:

NORTH ANNA POWER STATION, UNIT NO. 2 - REVIEW OF STEAM GENERATOR TUBE INSPECTION REPORT FOR THE CYCLE 26 SPRING 2019 REFUELING OUTAGE (EPID L-2019-LRO-0108)

Dear Mr. Stoddard:

By letter dated June 24, 2019 (Agencywide Documents Access and Management System (ADAMS) Accession No. ML19179A075), Virginia Electric and Power Company (the licensee) submitted its steam generator (SG) tube inspection report for the North Anna Power Station (North Anna), Unit No. 1, in accordance with Technical Specification (TS) 5.6.7, Steam Generator Tube Inspection Report. The report summarizes the SG tube inspections performed during the North Anna, Unit No. 2 Cycle 26 refueling outage, in the spring of 2019. The licensee provided additional information concerning the inspections in a letter dated December 16, 2020 (ADAMS Accession No. ML21022A175).

The U.S. Nuclear Regulatory Commission (NRC) staff completed its review of the submittal and concluded that the licensee provided the information required by the North Anna, Unit No. 2 TSs. No additional follow-up is required at this time. This completes the NRC staffs efforts for EPID L-2019-LRO-0108. The enclosure documents the NRC staff's review of the submittal.

Sincerely,

/RA/

G. Edward Miller, Project Manager Plant Licensing Branch II-1 Division of Operating Reactor Licensing Office of Nuclear Reactor Regulation Docket No. 50-339

Enclosure:

Review of Steam Generator Tube Inspection Report cc: Listserv

REVIEW OF THE 2019 STEAM GENERATOR TUBE INSPECTION REPORT VIRGINIA ELECTRIC AND POWER COMPANY NORTH ANNA POWER STATION, UNIT NO. 2 DOCKET NO. 50-339 By letter dated June 24, 2019 (Agencywide Documents Access and Management System (ADAMS) Accession No. ML19179A075), Virginia Electric and Power Company (the licensee) submitted information summarizing the results of the spring 2019 steam generator (SG) inspections performed at North Anna Power Station, Unit 2 (North Anna Unit 2). The inspections were performed during refueling outage 26 (2R26). The licensee provided additional information concerning the inspections in a letter dated December 16, 2020 (ADAMS Accession No. ML21022A175).

North Anna Unit 2 has three Westinghouse Model 54F replacement SGs that were installed in May 1995. Each SG contains 3,592 thermally treated Alloy 690 tubes (Alloy 690TT), with a nominal outside diameter of 0.875 inches and a nominal wall thickness of 0.050 inches. The tubes are supported by seven Type 405 stainless steel tube support plates. The tube support plate holes are quatrefoil shaped. The U-bend region of the first eight rows of tubing was stress relieved after bending.

The licensee provided the scope, extent, methods, and results of the SG tube inspections in the letters referenced above. In addition, the licensee described corrective actions (e.g., tube plugging), if any were taken in response to the inspection findings.

Based on the review of the information provided, the U.S. Nuclear Regulatory Commission (NRC) staff has the following observations:

The licensee clarified that no evidence of degradation and plug leakage was identified during the primary side channel head visual examinations performed in each SG during 2R26. The visual examinations included the divider plate/tubesheet interface, entire cladded surface, and all tube plugs.

A tube with no tube expansion (NTE) in SG C was newly identified during 2R26. During a teleconference on January 21, 2021, the licensee clarified that auto analysis of eddy current data identified the NTE in SG C. The licensee also clarified that the same auto analysis sorts were used for each SG during 2R26. Given that the Alloy 690TT SG tubes operating experience has demonstrated resistance to corrosion and stress corrosion cracking, and the same auto analysis sorts were used for all tubing, the staff has no additional questions related to tubes with NTE at North Anna Unit 2.

Based on a review of the information provided, the NRC staff concludes that the licensee provided the information required by their technical specifications. In addition, the staff concludes that there are no technical issues that warrant additional follow-up action at this time since the inspections appear to be consistent with the objective of detecting potential tube degradation and the inspection results appear to be consistent with industry operating experience at similarly designed and operated units.

Enclosure

ML21036A077 *via SE Input OFFICE NRR/DORL/LPL2-1/PM NRR/DORL/LPL2-1/LA NRR/DNRL/MCSG/BC NAME GEMiller KGoldstein SBloom*

DATE 02/10/2021 02/05/2021 02/05/2021 OFFICE NRR/DORL/LPL2-1/BC NRR/DORL/LPL2-1/PM NAME MMarkley GEMiller DATE 02/10/2021 02/23/2021