ML21022A175
| ML21022A175 | |
| Person / Time | |
|---|---|
| Site: | North Anna  |
| Issue date: | 12/16/2020 |
| From: | Mladen F Virginia Electric & Power Co (VEPCO) |
| To: | Document Control Desk, Office of Nuclear Reactor Regulation |
| References | |
| 19-290A | |
| Download: ML21022A175 (6) | |
Text
Vm.GINIA ELECTRIC AND POWER CoMJ>ANY RICHMOND, VmGINIA 23261 December 16, 2020 U.S. Nuclear Regulatory Commission Attention: Document Control Desk Washington, D.C. 20555 VIRGINIA ELECTRIC AND POWER COMPANY NORTH ANNA POWER STATION UNIT 2 SPRING 2019 OUTAGE Serial No.:
NAPS/DPI\\JI Docket No.:
License No.:
STEAM GENERA TOR TUBE INSPECTION REPORT RAI RESPONSE 19-290A RO 50-339 NPF-7 By letter dated June 24, 2019 [Agencywide Document Access and Management System (ADAMS) Accession No. ML19179A075], Virginia Electric and Power Company (Dominion Energy Virginia) submitted the 180-day steam generator tube inspection r,eport for the North Anna Unrt 2 Spring 2019 outage.
In a November 10, 2020 e-mail from Mr. Ed Miller (NRC) to Ms. Diane Artken (Dominion Energy Virginia), the NRC staff provided a request for addrtional 'information (RAI) regarding the June 24, 2019 Unit 2 steam generator tube inspection report.
The response to the RAI is provided in Attachment 1.
Should you have any questions or require additional information, please contact Mr.
Daniel P. McGinnis at (540) 894-2487.
Very truly yours, Fred Mladen Srte Vice President
Attachment:
RAI Response - Spring 2019 Outage Steam Generator Tube Report Commrtments made in this letter: None
Serial No 19-290A Docket No.: 50-339 RAI Response - Spring 2019 Outage SG Tube Inspection Rpl Page 2 of2 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 8-1 A 11555 Rockville Pike Rockville, Maryland 20852-2738 Mr. Vaughn Thomas NRC Project Manager - Surry U.S. Nuclear Regulatory Commission One White Flint North. Mail Stop 04 F-12 11555 Rockville Pike Rockville, MD 20852-2738 NRC Senior Resident Inspector North Anna Power Station
Attachment RAI Response - Spring 2019 Outage Steam Generator Tube Inspection Report Virginia Electric and Power Company (Dominion Energy Virginia)
North Anna Power Station Unit 2 Serial No.. 19-290A Page 1 of 4
Serial No. 19-290A Docket No.* 50-339 RAI Response-Spring 2019 Outage SG Tube Inspection Rpt Attachment, Page 2 of 4 Response to RAI Spring 2019 Outage Steam Generator Tube Inspection Report By letter dated June 24, 2019 (Agencywide Documents Access and Management System (ADAMS) Accession No. Ml 19179A075), Virginia Electric and Power Company submitted information summarizing the results of the spring 2019 steam generator (SG) inspections performed at North Anna Power Station, Unit 2. The inspections were performed during refueling outage 26.
In Appendix A of Part 50 of Title 10 of the Code of Federal Regulations (10 CFR), General Design Criteria (GDC) 14, 15, 30, 31, and 32, define requirements for the structural and leakage integrity of the RCPB. As part of the RCPB, the SG tubes must also meet the requirements of 10 CFR 50.55a with respect to inspection and repair requirements of the ASME Code. All pressurized water reactors have Technical Specifications (TS) according to 10 CFR 50.36 that include a SG Program with specific criteria for the structural and leakage integrity, repair, and inspection of SG tubes. North Anna Power Station, Unit 2 TS Section 5.6.7 requires that a report be submitted within 180 days after the initial entry into hot shutdown (MODE 4) following completion of an inspection of the SGs performed in accordance with TS Section 5.5.8.d, which requires that a SG Program be established and implemented to ensure SG tube integrity is maintained.
To complete its review of the inspection, the U.S. Nuclear Regulatory Commission (NRC) staff requests the following additional information.
Question Number 75:
Please discuss the results of the primary side channel head visual examinations performed on each SG (i.e., plugs, divider plate, and bowls).
Response
During the North Anna 2R26 refueling outage in Spring 2019, primary side visual examinations on all three Steam Generators (SG) included: Primary channel head (as-tound I as-left) including the divider plate/ tubesheet interface, the entire cladded surface per NSAL 12-1, and previously plugged tubes. These examinations revealed no evidence of degradation and no evidence of plug leakage. The proper tube number, plug type, and plug position were verffied for all eight previously installed plugs in SG "A" and SG "C".
Question Number 76 Serial No.: 19-290A Docket No. 50-339 RAI Response - Spring 2019 Outage SG Tube Inspection Rpl Attachment, Page 3 of 4 The NRC staff has the following questions regarding Table 1, "Bobbin Probe Indication/Special Interest Exam Summary," in the spring 2019 SG inspection report.
Item a:
Eighteen tubes with 19 hot-leg (HL) manufacturing burnish marks (MBHs) in SG B were reported in the spring 2019 SG tube inspection report. However, 19 tubes with 20 HL MBHs in SG 8 were reported in the fall 2014 SG tube inspection report (ADAMS Accession No. ML15050A040). Given that no tubes have been plugged in this steam generator, please discuss the difference in the number of tubes and MBHs between the two inspection reports.
Response Item a:
Based on the Framatome Data Management System (FDMS), in 2014 there were 18 tubes with 19 Manufacturing Burnish Marks (MBH) indications identified in the hot leg of SG "B; hot leg being defined as Tube End Hot (TEH) to 07H+1.0 inch. There was one MBH located at AV3+31.96 inch which appears to have been counted as a hot leg MBH.
In 2019 there were 18 tubes with 19 MBH indications identified in the hot leg of SG "B". Again, there was one MBH referenced to AV3. In 2019 this U-bend MBH was not counted toward the total number of hot leg tubes with MBH indications.
Item b:
In SG C, 605 tubes with 1,002 cold-leg (CL) overexpansion's (OXPs) were reported in the spring 2019 SG tube inspection report. However, the spring 2016 SG inspection report reported 603 tubes with 998 CL OXPs in SG C (ADAMS Accession No. ML16202A066). Please confirm that 2 tubes with 4 CL OXPs were newly identified during the spring 2019 SG inspections. In addition, please provide any insight you may have with regards to these CL OXPs being newly identified during the spring 2019 SG inspections.
Response Item b:
An analysis of all available Eddy Current Testing (ECT) data was performed in 2007 to identify Over Expansion (OXP)s; a geometric condition established during tube installation. The quantity reported in the 2016 report was the quantity of OXPs and tubes with OXPs remaining in service (two tubes with OXPs had been plugged during the 2007 outage for reasons unrelated to OXPs). The 2019 reported value included all OXPs regardless of whether the tube was still in service. The difference between the two reported values is not the result of newly developed or newly reported OXPs.
Item c:
Sena! No : 19-290A Docket No.: 50-339 RAI Response - Spring 2019 Outage SG Tube Inspection Rpt Attachment, Page 4 of 4 Two tubes with no tube expansion in SG C were reported in the spring 2019 SG tube inspection report. However, the spring 2016 SG tube inspection report reported one tube with no tube expansion in SG C. Please confirm that an additional tube with no tube expansion in SG C was identified during the spring 2019 SG inspections. In addition, please provide any insight you may have with regards to this no tube expansion being newly identified during the spring 2019 SG inspections.
Response Item c:
A review of historical data has confirmed the apparent newly reported tube in SG "C" with No Tube Expansion (NTE) in the spring 2019 SG tube inspection report. The NTE in SG "C" existed previously in 2016 but was not reported prior to the 2019 SG tube inspection report. This NTE does not reflect a physical change in the tube geometry from the 2016 to 2019 SG examinations.