ML21131A040

NRR E-mail Capture - V.C. Summer, Unit 1 - Final RAI for the Spring 2020 RFO Sgtir Review

ML21131A040
Person / Time
Site:	Summer
Issue date:	05/11/2021
From:	Vaughn Thomas NRC/NRR/DORL/LPL2-1
To:	Gao Y South Carolina Electric & Gas Co
References
L-2020-LRO-0084
Download: ML21131A040 (4)

Text

From: Thomas, Vaughn Sent: Tuesday, May 11, 2021 8:41 AM To: Yan.Gao@dominionenergy.com

Subject:

V.C. Summer, Unit 1 - Final RAI for the Spring 2020 RFO SGTIR Review Attachments: Final RAI for the Summer Spring 2020 RFO (RFO 25)_May 11 2021.doc

Yan, The attached file constitutes the staffs issuance of the final RAI concerning the review of the Summer Spring 2020 RFO SG tube inspection report. The staff expects the licensees response to the RAI within 30 days from todays date, May 11, 2021 (due date June 10, 2021).

Thanks Vaughn Thomas, Project Manager Plant Licensing Branch II-1 Division of Operating Reactor Licensing Office of Nuclear Reactor Regulation Vaughn.Thomas@nrc.gov 301-415-5897

Hearing Identifier: NRR_DRMA Email Number: 1176 Mail Envelope Properties (BLAPR09MB74092AC005405F1C9E465731F4539)

Subject:

V.C. Summer, Unit 1 - Final RAI for the Spring 2020 RFO SGTIR Review Sent Date: 5/11/2021 8:41:18 AM Received Date: 5/11/2021 8:41:00 AM From: Thomas, Vaughn Created By: Vaughn.Thomas@nrc.gov Recipients:

"Yan.Gao@dominionenergy.com" <Yan.Gao@dominionenergy.com>

Tracking Status: None Post Office: BLAPR09MB7409.namprd09.prod.outlook.com Files Size Date & Time MESSAGE 535 5/11/2021 8:41:00 AM Final RAI for the Summer Spring 2020 RFO (RFO 25)_May 11 2021.doc 67195 Options Priority: Normal Return Notification: No Reply Requested: No Sensitivity: Normal Expiration Date:

REQUEST FOR ADDITIONAL INFORMATION OFFICE OF NUCLEAR REACTOR REGULATION Issued Date: May 11, 2021 V.C. Summer, Unit 1 Spring 2020 Steam Generator Tube Inspection Report South Carolina Electric & Gas Dockets: 05000395-PWR-Summer EPIDS: L-2020-LRO-0084 Questions Question Number: 314 By letter dated October 20, 2020 (Agencywide Documents Access and Management System (ADAMS) Accession No. ML20296A692), Dominion Energy South Carolina submitted information summarizing the results of the spring 2020 steam generator (SG) inspections performed at Virgil C.

Summer Nuclear Station (VCSNS), Unit 1. The inspections were performed during refueling outage (RFO) 25.

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 reactor coolant pressure boundary (RCPB). As part of the RCPB, the SG tubes must also meet the requirements of 10 CFR 50.55a, "Codes and standards," with respect to inspection and repair requirements of the American Society of Mechanical Engineers (ASME) Code. All pressurized water reactors have Technical Specifications (TS) according to 10 CFR 50.36, "Technical specifications," that include a SG Program with specific criteria for the structural and leakage integrity, repair, and inspection of SG tubes. VCSNS, Unit 1 TS Section 6.9.1.12 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 6.8.4.k, 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 information:

1. Please discuss if there was any degradation noted during the primary side visual inspections of the channel head bowl cladding and internal surfaces, performed on each SG.

2. With respect to the secondary side inspections, please clarify the scope (i.e., whether they were in all three SGs) and results of the secondary side inspections performed.

3. The December 14, 2020, response to the NRC's request for additional information on the fall 2018 SG tube inspection report (ADAMS Accession No. ML20349A326), stated that heavy deposit formations 5/5/2021 3:38:08 PM

and tube denting were identified during the visual inspection of the top (9th) tube support plate (TSP) in each SG. It is stated in the spring 2020 SG tube inspection report that Deposit Minimization Treatment (DMT) cleaning was performed during RFO 25. Please provide additional detail regarding the extent of the deposit formations and provide any additional insights, including the extent of denting, you may have with regards to the denting that could be related to the heavy deposit formation.

4. Section 6.0, "Tubes Plugged during the Inspection Outage," of the spring 2020 SG tube inspection report states that a total of 4 tubes were plugged; 2 tubes were preventively plugged in SG A due to TSP wear indications (neither exceeded the 40 percent plugging criterion) and 2 tubes (1 in SG A and 1 in SG B) were plugged due to possible loose parts (PLPs). Please clarify whether the PLPs were newly identified during RFO 25 and how many total PLPs there were in the two tubes.

5/5/2021 3:38:08 PM