ML23086C036

Request for Additional Information Steam Generator Tube Inspection Report (03R31)

ML23086C036
Person / Time
Site:	Oconee
Issue date:	03/27/2023
From:	Shawn Williams Plant Licensing Branch II
To:	Treadway R Duke Energy Carolinas
Williams S
References
EPID L-2022-LRO-0152
Download: ML23086C036 (2)

Text

From: Shawn Williams To: Treadway, Ryan I Cc: Vaughan, Jordan L

Subject:

Oconee Unit 3 - Request for Additional Information RE: Steam Generator Tube Inspection Report (03R31) (EPID:

L-2022-LRO-0152)

Date: Monday, March 27, 2023 11:40:01 AM Attachments: Oconee Unit 3 Spring 2022 SG Tube Inspection Report RAI .docx

Dear Mr. Treadway,

By letter dated November 21, 2022 (Agencywide Documents Access and Management System Accession No. ML22325A362), Duke Energy (the licensee) submitted information summarizing the results of the spring 2022 steam generator inspections performed at Oconee Nuclear Station, Unit 3.

The NRC staff has reviewed the information and determined that additional information is needed to complete the review. The requested additional information (RAI) is enclosed.

A clarification call to ensure mutual understanding was conducted on March 27, 2023.

Please respond within 30 days of the date of this e-mail.

If you have any questions, please contact me at 301-415-1009 or via e-mail at Shawn.Williams@nrc.gov.

Sincerely, Shawn A. Williams, Senior Project Manager Plant Licensing Branch, II-1 Division of Operating Reactor Licensing Office of Nuclear Reactor Regulation Docket No. 50-287

Enclosure:

Request for Additional Information cc w/encl: Listserv

OCONEE NUCLEAR STATION, UNIT 3 REQUEST FOR ADDITIONAL INFORMATION SPRING 2022 STEAM GENERATOR TUBE INSPECTION REPORT DOCKET NO. 50-287 By letter dated November 21, 2022 (Agencywide Documents Access and Management Systems Accession No. ML22325A362), Duke Energy submitted information summarizing the results of the spring 2022 steam generator (SG) inspections performed at Oconee Nuclear Station, Unit 3. The inspections were performed during refueling outage (RFO) 31. Technical Specification (TS) Section 5.5.10 requires that a SG Program be established and implemented to ensure SG tube integrity is maintained. TS Section 5.6.8 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.

Some information about the classification, tracking, and reporting of tube-to-tube wear indications for the Oconee Unit 3 steam generators is unclear to the U.S. Nuclear Regulatory Commission (NRC) staff. Specifically,

• The Unit 3 reports from the most recent inspections, 2022 (RFO 31, ML22325A362) and 2018 (RFO 29, ML18235A502), appear to use the code VTW for tube-to-tube wear in the listing of indications. The 2018 report also includes indications classified as HNC, but the 2022 report does not have any indications classified as HNC.

• The 2018 and 2022 reports for Unit 3 do not define the abbreviations VTW or HNC, but the staff understands HNC to be an abbreviation for Historical No Change based on Unit 3 and Unit 2 steam generator tube inspection reports.

• All tube-to-tube wear indications in the 2021 inspection report for Unit 2 appear to be classified as TTW (Tube-to-Tube Wear), ADI (Absolute Drift Indication), or VTW.

The text in the 2021 Unit 2 report describes the meaning of TTW and ADI, but not VTW.

Therefore, to complete its review of the inspection report, the NRC staff requests the following additional information:

1. Please clarify whether the HNC code is used as a basis for omitting tube-to-tube wear indications from SG tube inspection reports. The 2018 report for Oconee Unit 3 appears to include tube-to-tube wear indications classified as HNC that were not included in the 2022 report (e.g., SG 3A, tubes R91C51 and R92C51). If indications are excluded based on classification as HNC, please discuss the apparent discrepancy with Technical Specification 5.6.8.d, which requires the reporting of the Location, orientation (if linear),

and measured sizes (if available) of service induced indications.

2. Please define eddy current three-letter Code VTW and discuss the difference between Codes VTW and TTW assigned to tube-to-tube wear indications within the Oconee units.

Enclosure