L-2024-108, Response to Request for Additional Information (RAI) Regarding One Time Extension to Technical Specification 3.8.1.1.a, Allowed Outage Time with One Independent Circuit Between the Offsite.

Response to Request for Additional Information (RAI) Regarding One Time Extension to Technical Specification 3.8.1.1.a, Allowed Outage Time with One Independent Circuit Between the Offsite.

ML24198A026
Person / Time
Site:	Seabrook
Issue date:	07/16/2024
From:	Rasmus P NextEra Energy Seabrook
To:	Office of Nuclear Reactor Regulation, Document Control Desk
References
L-2024-108
Download: ML24198A026 (1)

Text

NEXTera*

ENERGY~

SEABROOK Attn: Document Control Desk U.S. Nuclear Regulatory Commission Washington DC 20555-0001 RE: Seabrook Station Docket No. 50-443 Renewed Facility Operating License No. NPF-86 L-2024-108 10 CFR 50.90 July 16, 2024 Response to Request for Additional Information (RAI) Regarding One Time Extension to Technical Specification 3.8.1.1.a, Allowed Outage Time with One Independent Circuit Between the Offsite Transmission Network and the Onsite Class 1 E Distribution System Out-Of-Service

References:

1.

Next Era Energy Seabrook, LLC., letter L-2024-061, License Amendment Request - One Time Extension to Technical Specification 3.8.1.1.a, Allowed Outage Time with One Independent Circuit Between the Offsite Transmission Network and the Onsite Class 1 E Distribution System Out-Of-Service, May 10, 2024 (ADAMS Accession No. ML24131A152)

2.

NRC Electronic Memorandum dated June 25, 2024, Request for Additional Information (RAI) -

Seabrook LAR offsite power, Regarding the One Time License Amendment Request to Revise Technical Specification 3.8.1, Offsite Sources - Operating," Seabrook Station, Unit 1, Docket No. 50-443 In Reference 1, NextEra Energy Seabrook, LLC., (NextEra) requested a one-time amendment to Renewed Facility Operating License (RFOL) NFP-86 for Seabrook Nuclear Plant 1 (Seabrook). The proposed license amendment would be a one-time modification to Seabrook Technical Specification (TS) Action 3.8.1.1.a, "Offsite Sources - Operating," by increasing the Allowed Outage Time (AOT) from 72 hours8.333333e-4 days <br />0.02 hours <br />1.190476e-4 weeks <br />2.7396e-5 months <br /> to 456 hours0.00528 days <br />0.127 hours <br />7.539683e-4 weeks <br />1.73508e-4 months <br />.

In Reference 2, the NRC forwarded Requests for Additional Information (RAls) deemed necessary to complete its review. The enclosure to this letter provides NextEra RAI responses. The attachment to the enclosure provides a revised TS 3.8.1.1.a.3. markup page. The revised TS 3.8.1.1.a.3 markup page supersedes and replaces in its entirety the corresponding TS markup page provided in Reference 1.

The information included in this RAI response provides additional information that clarifies the application, does not expand the scope of the application as originally noticed, and should not change the NRC staff's originally proposed no significant hazards consideration determination as published in the Federal Register.

This letter contains no new or revised regulatory commitments.

Should you have any questions regarding this submission, please contact Mr. Kenneth Mack, Senior Manager, Licensing and Regulatory Compliance, at 561-904-3635.

I declare under penalty of perjury that the foregoing is true and correct.

Executed on the 161h day of July 2024.

Sincerely, Paul Rasmus General Manager, Regulatory Affairs NextEra Energy Seabrook, LLC P.O. Box 300, Lafayette Road, Seabrook, NH 03874

Seabrook Station Docket No. 50-443 Enclosure Attachment cc:

USNRC Region I Administrator USNRC Project Manager USNRC Senior Resident Inspector Director Homeland Security and Emergency Management New Hampshire Department of Safety Division of Homeland Security and Emergency Management Bureau of Emergency Management 33 Hazen Drive Concord, NH 03305 Kimberly Castle, Technological Hazards The Commonwealth of Massachusetts Emergency Management Agency 400 Worcester Road Framingham, MA 01702-5399 L-2024-108 Page 2 of 2

Seabrook Station Docket No. 50-443 Seabrook Station L-2024-108 Enclosure Page 1 of 3 Response to Request for Additional Information (RAI) Regarding One Time Extension to Technical Specification 3.8.1.1.a, Allowed Outage Time with One Independent Circuit Between the Offsite Transmission Network and the Onsite Class 1 E Distribution System Out-Of-Service In an electronic Memorandum dated June 25, 2024 (Reference 1 ), the NRC staff of the Office of Nuclear Reactor Regulation (NRR) requested additional information (RAI) regarding NextEra Energy Seabrook, LLC., One Time Extension to Technical Specification 3.8.1.1.a, Allowed Outage Time with One Independent Circuit Between the Offsite Transmission Network and the Onsite Class 1 E Distribution System Out-Of-SeNice (Reference 2). The NextEra response is provided below.

EEEB RAl-1 BTP 8-8 recommends that the licensee provide justification for the duration of the requested Completion Time (CT) (actual hours plus margin based on plant-specific past operating experience).

The LAR proposed an additional 384 hours0.00444 days <br />0.107 hours <br />6.349206e-4 weeks <br />1.46112e-4 months <br /> to 72 hours8.333333e-4 days <br />0.02 hours <br />1.190476e-4 weeks <br />2.7396e-5 months <br /> completion time for TS LCO 3.8.1.1 Action a.3 for a total of 456 hours0.00528 days <br />0.127 hours <br />7.539683e-4 weeks <br />1.73508e-4 months <br />.

It appears that the LAR does not include a deterministic justification for the proposed extended CT.

Provide a deterministic justification for the additional 384 hours0.00444 days <br />0.107 hours <br />6.349206e-4 weeks <br />1.46112e-4 months <br />.

NextEra Response to EEEB RAI - 1 The expected minimum duration of the total allowed outage time is currently 5-7 days. The current Seabrook risk management procedure provides guidance that the unit should not enter the action statement unless the expected AOT is under 50% of the total available time. The current main generator testing schedule is still under development. To preclude additional AOT extension requests, 19 days was selected using risk informed input as the maximum expected total allowed outage time considering the 50% guidance and testing schedule uncertainty. During the extended AOT, offsite power would be available to the onsite Class 1 E electrical distribution system via the operable offsite circuit powering both reseNe auxiliary transformers (RATs). In this condition, the remaining operable offsite circuit and EDGs are adequate to support the key safety functions necessary to maintain the unit in a safe condition during the extended AOT and respond to an anticipated operational occurrence (AOO) or a postulated design basis accident (OBA), the consequences of which would be less severe during MODES 2, 3 and 4.

The non-safety related Supplemental Emergency Power System (SEPS) is relied upon for defense-in-depth as a backup power source when an Emergency Diesel Generator (EOG) is inoperable. It can supply power to the safety and non-safety related loads. SEPs can respond to Station Blackout (SBO) as an independent AC power supply, along with the station batteries, though Seabrook is not an Alternate AC plant as defined in BTP 8-8 as a result of the SEPS.

EEEB RAl - 2 BTP 8-8 recommends certain actions intended to maintain the availability of the equipment important to safety and to avoid a plant unit trip during the extended CT. These actions include:

The preplanned maintenance will not be scheduled if severe weather conditions are anticipated.

Seabrook Station Docket No. 50-443 L-2024-108 Enclosure Page 2 of 3 TS required systems, subsystems, trains, components, and devices that depend on the remaining power sources will be verified to be operable and positive measures will be provided to preclude subsequent testing or maintenance activities on these systems, subsystems, trains, components, and devices.

Steam-driven emergency feed water pump(s) in case of PWR units will be controlled as "protected equipment."

It appears that the LAR does not include information that is relevant to the above-mentioned actions.

Discuss how Seabrook addresses the above-mentioned actions during the proposed extended CT.

NextEra Response to EEEB RAI - 2 Seabrook will add a compensatory action that the unit will not transition from MODE 5 to MODE 4 if severe weather is forecasted in the next 2 days.

The extended allowed outage time requested by the amendment only allows operation with the redundant offsite power source inoperable in MODES 3 and 4, and in MODE 2 for the duration of low-power physics testing. All emergency and safety related equipment will still have access to an operable offsite power source. During the extended AOT, positive measures include compensatory actions that verify onsite AC sources, including the diesel generators and SEPS, are guarded and maintained available, and limiting switchyard and offsite transmission activity to only emergency work or as necessary to restore the UA T. Maintenance and testing activities will be controlled by existing Technical Specification requirements and approved procedures extended AOT.

Seabrook will add a compensatory action to verify that the Steam Driven Emergency Feedwater Pump (EFW) is guarded once testing is complete in accordance with TS 4.7.1.2.1.b.2 and 4.7.1.2.2.

Seabrook will add a compensatory action to verify SEPS is aligned to BUS 6 to provide a redundant on-site power source for the motor driven EFW pump prior to transitioning the unit from MODE 5 to MODE 4.

EEEB RAl-3 Section 50.36(c)(2)(i) of 10 CFR states, in part, that when an LCO is not met, the licensee shall shut down the reactor or follow any remedial action permitted by the TS until the condition can be met.

The proposed footnote for the TS LCO 3.8.1.1 Action a.3 in the LAR states, in part, "Compensatory measures within NextEra Energy Seabrook, LLC letter L-2024-061, dated May 10, 2024, shall be implemented, and shall remain in effect during the extended AOT period."

It appears that the LAR does not clearly state what are the compensatory measures.

Provide the full list of compensatory measures that will be in place during the proposed extended CT.

NextEra Response to EEEB RAI - 3 Seabrook will perform the following compensatory actions in preparation for the extended AOT prior to transitioning from MODE 5 to MODE 4:

Verify that an ISO-NE transmission request is in place requesting to limit maintenance on the offsite transmission lines to emergencies only.

Seabrook Station Docket No. 50-443 Verify shutdown power availability risk is GREEN in accordance with SM7.31.

Verify SEPS is aligned to bus 6.

Verify no severe weather is forecasted in the next 5 days.

Seabrook will comply with the following compensatory actions during the extended AOT:

L-2024-108 Enclosure Page 3 of 3 Operations will perform an SRO walkdown of all guarded equipment once per shift as follows:

Both Emergency Diesel Generators Supplemental Emergency Power System (SEPS)

Seabrook's 345kV Switchyard Breaker Enclosure Building 3A and 38 Reserve Auxiliary Transformers Seabrook's Relay Room Steam Driven EFW pump when testing is complete in accordance with TS 4.7.1.2.1.b.2 and 4.7.1.2.2.

Operations will walkdown FLEX equipment once per shift.

The Station will contact the load dispatcher (ISO-NE) to stay apprised of any potential grid perturbations or of any switching that might be necessary once per shift.

Seabrook has revised the TS 3.8.1.1.a.3. markup page provided in Reference 1 to reflect the compensatory actions listed above. The attachment to this letter provides the revised TS 3.8.1.1.a.3.

markup. The revised TS 3.8.1.1.a.3 markup page supersedes and replaces in its entirety the corresponding TS markup page in Reference 1.

References:

1. NRC Electronic Memorandum dated June 25, 2024, Request for Additional Information (RAI) -

Seabrook LAR offsite power, Regarding the One Time License Amendment Request to Revise Technical Specification 3.8.1, Offsite Sources - Operating," Seabrook Station, Unit 1, Docket No. 50-443

2. NextEra Energy Seabrook, LLC., letter L-2024-061, License Amendment Request -

One Time Extension to Technical Specification 3.8.1.1.a, Allowed Outage Time with One Independent Circuit Between the Offsite Transmission Network and the Onsite Class 1 E Distribution System Out-Of-Service, May 10, 2024 (ADAMS Accession No. ML24131A152)

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