ML20105A107

NRR E-mail Capture - Comanche Peak - Request for Additional Information - Exigent Amendment Request for One Time Change to Unit 2 Steam Generator Inspection Frequency

ML20105A107
Person / Time
Site:	Comanche Peak
Issue date:	04/13/2020
From:	Dennis Galvin NRC/NRR/DORL/LPL4
To:	Hicks J TEX Operations Company
References
L 2020-LLA-0072
Download: ML20105A107 (4)

Text

From: Galvin, Dennis Sent: Monday, April 13, 2020 5:29 PM To: Jack Hicks (Jack.Hicks@luminant.com)

Cc: Barnette, James; Struble, Garry

Subject:

Comanche Peak - Request for Additional Information - Exigent Amendment Request for One Time Change to Unit 2 Steam Generator Inspection Frequency (EPID: L 2020-LLA-0072)

Attachments: Comanche Peak SG Exigent LAR RAIs 2020-04-13.pdf Mr. Hicks, By letter dated April 10, 2020 (Agencywide Documents and Access Management System (ADAMS) Accession No. ML20101M879), Vistra Operations Company LLC (the licensee) submitted a license amendment request (LAR) for Nuclear Regulatory Commission (NRC) approval for an exigent amendment to the facility operating license for the Comanche Peak Nuclear Power Plant, Unit No. 2 (Comanche Peak Unit 2). The proposed amendment would revise Technical Specification 5.5.9, Unit 1 Model D76 And Unit 2 Model D5 Steam Generator (SG) Program, to allow a one-time change in the Comanche Peak Unit 2 SG inspection frequency. The proposed change would allow the licensee to defer the Unit 2 SG inspections for the spring 2020 refueling outage to the fall 2021 refueling outage.

The NRC staff has determined that additional information is needed to complete its review. The requests for additional information (RAIs) were transmitted to the licensee in draft form on April 13, 2020. A clarification call was held on April 13, 2020, and the licensee agreed to provide responses to the RAls by April 14, 2020. The NRC staff agreed with this date.

If you have any questions, please contact me at (301) 415-6256 or Dennis.Galvin@nrc.gov.

Respectfully, Dennis Galvin Project Manager U.S Nuclear Regulatory Commission Office of Nuclear Reactor Regulation Division of Operating Reactor Licensing Licensing Project Branch 4 301-415-6256 Docket Nos. 50-445 and 50-446

Hearing Identifier: NRR_DRMA Email Number: 528 Mail Envelope Properties (MN2PR09MB527310110D0EB844AFA24A0BFBDD0)

Subject:

Comanche Peak - Request for Additional Information - Exigent Amendment Request for One Time Change to Unit 2 Steam Generator Inspection Frequency (EPID: L 2020-LLA-0072)

Sent Date: 4/13/2020 5:28:47 PM Received Date: 4/13/2020 5:28:00 PM From: Galvin, Dennis Created By: Dennis.Galvin@nrc.gov Recipients:

"Barnette, James" <James.Barnette@luminant.com>

Tracking Status: None "Struble, Garry" <Garry.Struble@luminant.com>

Tracking Status: None "Jack Hicks (Jack.Hicks@luminant.com)" <Jack.Hicks@luminant.com>

Tracking Status: None Post Office: MN2PR09MB5273.namprd09.prod.outlook.com Files Size Date & Time MESSAGE 1521 4/13/2020 5:28:00 PM Comanche Peak SG Exigent LAR RAIs 2020-04-13.pdf 70306 Options Priority: Normal Return Notification: No Reply Requested: No Sensitivity: Normal Expiration Date:

REQUEST FOR ADDITIONAL INFORMATION LICENSE AMENDMENT REQUEST FOR ONE TIME CHANGE TO TECHNICAL SPECIFICATION 5.5.9 UNIT 1 MODEL D76 AND UNIT 2 MODEL D5 STEAM GENERATOR (SG) PROGRAM VISTRA OPERATIONS COMPANY LLC COMANCHE PEAK UNIT Nos. 1 and 2 DOCKET NOs. 50-445 and 50-446 By letter dated April 10, 2020 (Agencywide Documents and Access Management System (ADAMS) Accession No. ML20101M879), Vistra Operations Company LLC (the licensee) submitted a license amendment request (LAR) for Nuclear Regulatory Commission (NRC) approval for an exigent amendment to the facility operating license for the Comanche Peak Nuclear Power Plant, Unit No. 2 (Comanche Peak Unit 2). The proposed amendment would revise Technical Specification 5.5.9, Unit 1 Model D76 And Unit 2 Model D5 Steam Generator (SG) Program, to allow a one-time change in the Comanche Peak Unit 2 SG inspection frequency. The proposed change would allow the licensee to defer the Unit 2 SG inspections for the spring 2020 refueling outage to the fall 2021 refueling outage.

To complete its review, the NRC staff requests the following additional information.

1. Attachment 2, page 41/57 discusses axial outer diameter stress corrosion cracking (ODSCC) at tube support plates (TSPs) for high stress tubes. The attachment states For this evaluation, the length form factor is based on a uniform distribution from 1 to 3.

Please clarify the basis for these distribution values.

2. Page 52/57 in Attachment 2 describes Comanche Peaks efforts to identify high stress tubes. It is known that the original screening for high stress tubes performed circa 2003 did not identify all the high stress tubes at some other plants. Subsequent to 2003, additional information was provided concerning screening for high stress tubes. One plant currently seeking an Exigent LAR related to SG inspection did a screening as late as 2017 that identified some additional high stress (signature) tubes.

a. Please elaborate on the discussion provided on Page 52/57 regarding the screening performed for high stress tubes and why you are confident that all high stress tubes have been identified.

b. The operational assessment analysis (OA) analysis for potential high stress tubes cracking at TSPs uses an enhanced probability of detection (POD) from a combined bobbin coil inspection supplemented by +Point inspection. Assuming that a high stress tube was not identified, and was therefore only examined with a bobbin probe, how many effective full power years (EFPY) ago could a TSP crack have initiated and still meet the performance criteria at 2RF19.

3. Please describe the Weibull slope, characteristic life, and population size used in the analyses for the assumed potential cracking mechanisms.

4. The NRC staff found the proposed TS language unclear. For example, the proposed wording for Note B could be interpreted as applying to all future cycles. Would it be simpler to place footnotes referring to the appropriate TS section as below?

Note A: For TS 5.5.9.d.2, As a one-time change for Unit 2 Cycle 19 only, inspect each SG at least once every 54 effective full power months.

Note B: For TS 5.5.9.d.2.c, As a one-time change for Unit 2 Cycle 19 only, inspect 100% of the tubes every 90 effective full power months.

5. Page 9/18 in the Enclosure discusses the evaluation of existing mechanisms, in particular tube wear at anti-vibration bars (AVBs). Please confirm that the maximum projected depths for the largest existing indication and undetected indication were inadvertently switched (i.e., 55.3% through wall (TW) for existing maximum depth indication and 38.4% for an undetected indication).

6. Clarify whether the applicable TS limiting conditions for operation (LCOs) and surveillance requirements for the SG tube integrity, tube plugging criteria and reactor coolant system (RCS) operational leakage requirements are affected by the proposed changes.