ML23137A216

COL Docs - Vogtle LAR-22-002 Final RAI TS 3.8.3 Has Been Issued

ML23137A216
Person / Time
Site:	Vogtle
Issue date:	05/17/2023
From:	NRC
To:	NRC/NRR/DNRL
References
Download: ML23137A216 (5)

Text

From: Billy Gleaves Sent: Wednesday, May 17, 2023 12:52 PM To: Dorsey, Keith A.

Cc: Cayetano Santos; Vogtle PEmails; Wendell Morton; Sheila Ray; Edmund Kleeh; Vic Cusumano; Khadijah West; Shivani Mehta (She/Her/Hers); Thinh Dinh; Charles Moulton

Subject:

Vogtle LAR-22-002 Final RAI TS 3.8.3 has been Issued Attachments: Vogtle LAR-22-002 Final RAI TS 3.8.3 - Revision 1.pdf

Keith, As per your email this morning accepting the draft RAI Revision 1 questions from May 8, 2023, as final RAI questions, please find the Final RAI questions attached for LAR-22-002.

You have agreed to respond in 30 days, which would be June 16, 2023. If something changes and that date no longer is viable, please let me know.

Respectfully, Billy William (Billy) Gleaves Senior Project Manager NRR/Vogtle Project Office US Nuclear Regulatory Commission The contents of this message may be sensitive. If this message has been received in error, please delete it without reading it. Your receipt of this message is not intended to waive any applicable privilege. Do not disseminate this message without the permission of the author. Communications by this author do not represent NRC policy or staff positions and are not binding on the Commission.

Hearing Identifier: Vogtle_COL_Docs_Public Email Number: 671 Mail Envelope Properties (DM6PR09MB483946C1818488726C61B04D9F7E9)

Subject:

Vogtle LAR-22-002 Final RAI TS 3.8.3 has been Issued Sent Date: 5/17/2023 12:51:53 PM Received Date: 5/17/2023 12:51:59 PM From: Billy Gleaves Created By: Bill.Gleaves@nrc.gov Recipients:

"Cayetano Santos" <Cayetano.Santos@nrc.gov>

Tracking Status: None "Vogtle PEmails" <Vogtle.PEmails@usnrc.onmicrosoft.com>

Tracking Status: None "Wendell Morton" <Wendell.Morton@nrc.gov>

Tracking Status: None "Sheila Ray" <Sheila.Ray@nrc.gov>

Tracking Status: None "Edmund Kleeh" <Edmund.Kleeh@nrc.gov>

Tracking Status: None "Vic Cusumano" <Victor.Cusumano@nrc.gov>

Tracking Status: None "Khadijah West" <Khadijah.West@nrc.gov>

Tracking Status: None "Shivani Mehta (She/Her/Hers)" <Shivani.Mehta@nrc.gov>

Tracking Status: None "Thinh Dinh" <Thinh.Dinh@nrc.gov>

Tracking Status: None "Charles Moulton" <Charles.Moulton@nrc.gov>

Tracking Status: None "Dorsey, Keith A." <kadorsey@southernco.com>

Tracking Status: None Post Office: DM6PR09MB4839.namprd09.prod.outlook.com Files Size Date & Time MESSAGE 922 5/17/2023 12:51:59 PM Vogtle LAR-22-002 Final RAI TS 3.8.3 - Revision 1.pdf 114119 Options Priority: Normal Return Notification: No Reply Requested: No Sensitivity: Normal Expiration Date:

REVISED REQUEST FOR ADDITIONAL INFORMATION LICENSE AMENDMENT REQUEST FOR TECHNICAL SPECIFICATION 3.8.3, INVERTERS -

OPERATING, COMPLETION TIME EXTENSION (LAR-22-002)

DOCKET NOS.52-025 AND 52-026 VOGTLE ELECTRIC GENERATING PLANT, UNITS 3 AND 4 SOUTHERN NUCLEAR OPERATING COMPANY, INC.

By letter dated January 3, 2023 (Agencywide Documents Access and Management System Accession No. ML23003A797), the Southern Nuclear Operating Company submitted a license amendment request (LAR) in accordance with Title 10 of the Code of Federal Regulations (10 CFR) 50.90, for the Vogtle Electric Generating Plant (VEGP) Combined License (COL).

The first revision of this draft request for additional information (RAI) was sent to SNC on April 12, 2023 (ML23102A153). A clarification call was requested by SNC and held on 4.26.23. As per standard practice, no technical discussion is held during a clarification call. This revised draft RAI is a result of that clarification call.

The LAR proposed changes to revise COL Appendix A, Technical Specifications (TSs) 3.8.3, Inverters - Operating, to extend the completion time for Required Action A.1 from 24 hours2.777778e-4 days <br />0.00667 hours <br />3.968254e-5 weeks <br />9.132e-6 months <br /> to 14 days. Additionally, TS 3.3.9, Engineered Safety Feature Actuation System Manual Initiation, Condition C proposed change would replace misspelled Requried with Required.

The staff have reviewed the LAR in accordance with the Office of Nuclear Reactor Regulation Office Instruction LIC-101, License Amendment Review Procedures and has determined that the following additional information is needed to complete the review of the LAR.

RAI #1 Staff regulatory guidance C.2.2 of Regulatory Guide 1.200, Acceptability of Probabilistic Risk Assessment Results for Risk-informed Activities, Revision 3, states in part, that [Facts and Observations (F&Os)] that are not closed using an NRC-endorsed process should be evaluated by the licensee or applicant for their impact on a risk-informed application and addressed with documented justification with necessary changes made to the PRA prior to the use of PRA in the risk-informed application.

The discussion of F&Os (pg. 17 of the LAR) indicates that, the PRA has been updated to address peer review F&Os, to the extent possible for a pre-operational plant. The staff requests that SNC provide a complete list of open F&Os for all Probabilistic Risk Assessment (PRA) analyses, and where the F&O is related to or may impact the LAR, provide information as to planned disposition or resolution.

This information is being requested in order to support a determination that PRA standards have been followed and the reasonable assurance of quality and completeness of the PRA.

RAI #2 Section 1.1.2 of Regulatory Guide 1.177, Plant-Specific, Risk-Informed Decisionmaking:

Technical Specifications, Revision 0, states in part, TS may be changed to establish 1

consistently based requirements across the industry or across an industry group. Precedents referenced in the LAR consistently indicate extensions from 24 hours2.777778e-4 days <br />0.00667 hours <br />3.968254e-5 weeks <br />9.132e-6 months <br /> to 7 days.

From a probabilistic perspective, explain, at a high level, both the relevance of these precedents and the basis for the proposed 14 day extension and the allowed completion times that maintain acceptable thresholds for Conditional Core Damage Frequency (CCDF) and Conditional Large Early Release Frequency (CLERF) for VEGP Units 3 & 4.

This information is being requested in order to support a determination, from a risk perspective, the basis for the extension to 14 days and the potential for additional risk that may not have been evaluated.

RAI #3 10 CFR 50.65(a)(4) (Maintenance Rule) requires the assessment and management of the increase in risk that result from proposed maintenance activities. The LAR states that VEGP Units 3&4 Maintenance Rule program monitors the reliability and availability of the Uninterruptable Power Supply System (IDS) inverters and confirms that appropriate management attention and goal setting are applied based on pre-established performance criteria.

Clarify whether the planned vital AC inverter on-line maintenance as stated in the LAR (page 23 of 27) is limited to monitoring the reliability & availability of the IDS inverters in accordance with the Maintenance Rule Program (i.e., no remote control or operation of the inverters). If otherwise, provide a detailed description of the operations taken during online maintenance activities related to the AC inverter.

This information is being requested in order to support an assessment of operational risk associated with the remote control of the inverters, if any.

RAI #4 10 CFR 50.36(c)(2) requires that operating licenses for nuclear reactors must include TS that specify limited conditions for operation (LCOs) for equipment required for safe operation. TS Section 1.3, Completion Time, states that LCOs specify minimum requirements for ensuring safe operation of the unit. ACTIONS for an LCO state Conditions that usually describe ways in which the LCO requirements can fail to be met and that specify Required Action(s) and Completion Time(s). Required Actions must be completed prior to the expiration of the specified Completion Time (CT).

LAR Section 1 states that the proposed change would revise COL Appendix A, TS 3.8.3, Inverters - Operating, to extend the CT for Required Action A.1 from 24 hours2.777778e-4 days <br />0.00667 hours <br />3.968254e-5 weeks <br />9.132e-6 months <br /> to 14 days. The LAR section titled Industry Experience Related to Inverter Maintenance indicates that VEGP Units 3&4 have no direct operating experience for the specific VEGP inverter. LAR Table 1 shows examples of industry experience supporting extension of CTs for inoperable inverters beyond 24 hours2.777778e-4 days <br />0.00667 hours <br />3.968254e-5 weeks <br />9.132e-6 months <br />, and in some cases more than 7 days. The longest postulated timeline listed in that table for inoperable inverter repair and maintenance is 5.5 to 7.5 days for Palo Verde. LAR Section 4.2 lists four precedents with CT extensions going from 24 hours2.777778e-4 days <br />0.00667 hours <br />3.968254e-5 weeks <br />9.132e-6 months <br /> to 7 days. LAR section Probabilistic Risk Assessment states that SNC used Regulatory Guide 1.177 guidance to assess the impact of the CT extension from 24 hours2.777778e-4 days <br />0.00667 hours <br />3.968254e-5 weeks <br />9.132e-6 months <br /> to 14 days. RG 1.177 Section 2 shows the 2

staff expects licensees to provide strong technical bases, rooted in deterministic engineering and system analysis, for any TS change not just based on PRA results alone. RG 1.177, Section 2.3 indicates that PRA should model specific components and their unavailability models that include test and maintenance downtimes.

SNC does not provide a sufficient deterministic justification to support the proposed 14-day CT extension since it is beyond CT extensions for inoperable inverter both for industry operating experience and precedents that SNC notes in the LAR. The staff requests SNC provide a maintenance timeline (in hours/days) to restore an inoperable inverter to OPERABLE status including high-level activities with margin(s) for each and overall to address reasonable uncertainties in accordance with 10 CFR 50.36, TS 1.3, and guidance in RG 1.177.

3