Text

Response to Request for Additional Information (Raj) Regarding License Amendment Request 21-01, Revise 120-Volt AC Vital Instrument Panel Requirements
	ML22066B007
Person / Time
Site:	Seabrook
Issue date:	03/07/2022
From:	Booth B; NextEra Energy Seabrook
To:	; Document Control Desk, Office of Nuclear Reactor Regulation
References
	SBK-L-22024
	Download: ML22066B007 (21)
	v • d • e

NEXTera*

EN~

U. S. Nuclear Regulatory Commission Attn: Document Control Desk Washington DC 20555-0001 RE:

Seabrook Station Docket No. 50-443 Renewed Facility Operating License No. NPF-86 March 07, 2022 SBK-L-22024 10 CFR 50.90 Response to Request for Additional Information (RAJ) Regarding License Amendment Request 21-01, Revise 120-Volt AC Vital Instrument Panel Requirements

1.

NextEra Energy Seabrook, LLC letter SBK-L-21067, License Amendment Request 21-01, Revise 120-Volt AC Vital Instrument Panel Requirements, July 21, 2021 (ADAMS Accession No. ML21202A238)

2.

Supplement to License Amendment Request 21-01, Revise 120-Volt AC Vital Instrument Panel Requirements, September 22, 2021 (ADAMS Accession No. ML21265A416)

3.

NRC Electronic Memorandum dated January 7, 2022, Requests for Additional Information (RAls)

Regarding the License Amendment Request to Revise Technical Specification 3/4.8.3, "Onsite Power Distribution - Operating" Seabrook Station, Unit No. 1, Docket No. 50-443

4.

NRC Electronic Memorandum dated February 7, 2022, Requests for Additional Information (RAls)

Regarding the License Amendment Request to Revise Technical Specification 3/4.8.3, "Onsite Power Distribution - Operating" Seabrook Station, Unit No. 1, Docket No. 50-443 In Reference 1, NextEra Energy Seabrook, LLC (NextEra) requested an amendment to Renewed Facility Operating License (RFOL) NPF-86 for Seabrook Nuclear Plant Unit 1 (Seabrook). The proposed license amendment would modify Seabrook Technical Specifications (TS) 3.8.3, Onsite Power Distribution -

Operating, by increasing the Allowed Outage Time (AOT) for the 120-volt AC vital instrument panel inverters, establishing a new required action for two inoperable 120-volt AC vital instrument panel inverters of the same electrical train and related administrative changes.

In Reference 2, NextEra provided supplemental information requested by the NRC during a September 1, 2021 conference call.

In References 3 and 4, the NRC requested additional information deemed necessary to complete its review.

The enclosure to this letter provides NextEra's response to the request for additional information (RAJ). In addition, and as discussed in the enclosure, NextEra is modifying the TS and TS Bases changes proposed in References 1 and 2. Attachment 1 to enclosure provides the existing TS pages marked up to show the proposed changes. Attachment 2 provides the existing TS Bases pages marked up to show the proposed changes. The TS and TS Bases marked up pages supersede the corresponding pages provided in References 1 and 2. The TS Bases changes are provided for information only and will be incorporated in accordance with the TS Bases Control Program upon implementation of the approved license amendments.

The supplements included in this RAJ response provide additional information that clarifies the application, do not expand the scope of the application as originally noticed, and should not change the NRC staffs original proposed no significant hazards consideration determination as published in the Federal Register.

This letter contains no new regulatory commitments.

NextEra Energy Seabrook, LLC P.O. Box 300, Lafayette Road, Seabrook, NH 03874

Seabrook Station Docket Nos. 50-443 SBK-L-22024 Page 2 of2 Should you have any questions regarding this submission, please contact Mr. Matthew Levander, Licensing Manager at 603-773-7631.

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

7tf..

Executed on the __ day of March 2022.

Sincerely, f}u;,, ~

Brian Booth '

Site Vice President - Seabrook Nuclear Power Station NextEra Energy Enclosure Attachments 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 Katharine Cederberg, Lead Nuclear Planner The Commonwealth of Massachusetts Emergency Management Agency 400 Worcester Road Framingham, MA 01702-5399

Seabrook Station Docket Nos. 50-443 Seabrook Station Response to Request for Additional Information (RAI) Regarding SBK-L-22024 Enclosure Page 1 of 19 License Amendment Request 21-01, Revise 120-Volt AC Vital Instrument Panel Requirements In electronic memorandums dated January 25, 2022 (Reference 1) and February 7, 2022 (Reference 2),

the NRC staff of the Office of Nuclear Reactor Regulation (NRR) requested additional information regarding NextEra Energy Seabrook, LLC (NextEra) License Amendment Request (LAR) 21-01, Revise 120-Volt AC Vital Instrument Panel Requirements, as indicated below. NextEra's response follows.

It should be noted that a modification to the 120 VAC instrument panel system was completed subsequent to the LAR and supplemental responses of References 3 and 4. Specifically, an additional 120 VAC vital instrument panel (1-EDE-PP-1 C), for a total of five of the six, is now equipped with an integral static transfer switch for automatic and fast transfer to its maintenance power supply in the event its associated UPS (1-EDE-1-1 C) becomes unavailable. A similar upgrade to the remaining vital instrument panel (1-EDE-PP-1 D), currently requiring manual swap-over to its maintenance supply, is planned for the near future.

ABLB RAI -1 In LAR Attachment 3, Section 3, "Sources of Model Uncertainty," although the licensee stated that "potential sources of generic and plant-specific uncertainty that represent possible impact on risk-informed applications identified were reviewed thoroughly. No sources of uncertainty were identified as having a significant impact on the results of this evaluation," no additional information was provided for the staff to make the determination.

Therefore, the NRC staff requests that the licensee provide a description of the sources of model uncertainties, the key assumptions made, and discuss any conservativism or non-conservativism introduced by the analysis approach to the internal events and internal flooding events PRA models.

NextEra Response to ABLB RAI - 1 The 2019 Seabrook PRA Notebook, Section 17 PRA Sources of Uncertainty, fully evaluated the sources of model uncertainty for Seabrook. A follow-up review was performed to determine whether there were any sources of uncertainty which could potentially impact a risk evaluation for the proposed increase in the allowed outage time (AOT) from 24 hours2.777778e-4 days 0.00667 hours 3.968254e-5 weeks 9.132e-6 months to 7 days for an inoperable 120 VAC vital instrument panel inverter. The table below describes the key assumptions, the sources of model uncertainties and their disposition. As indicated, none of the assumptions and uncertainties impacted the results of the evaluation. In addition, there were no Internal Flooding sources of uncertainty that impacted this amendment request.

Seabrook Station Docket Nos. 50-443 Assumption I Uncertainty The generic industry data for the LOOP categories (as screened for applicability for SBK) is assumed to be appropriate for SBK.

Failure of DC power sources needed for OSP recovery was implicitly considered.

After switchyard battery depletion, local manual action and additional time is assumed needed for recovery.

For operation of equipment after battery depletion, it was assumed that operation of systems following battery depletion was not possible.

For station battery life calculations, four-hour battery depletion was assumed with no load shed and 12-hour battery depletion was assumed when load shed was successful.

SBK-L-22024 Enclosure Page 2of19 Assumptions and Uncertainties for IE Analysis Discussion Disposition The stability of some local areas of the Industry data collected and characterized by electric power grid were analyzed. The EPRI was used. The data set included data potential duration and complexities of through 2008 and included the 2003 recovery from grid stability events are Northeast blackout. Data was reviewed to hard to dismiss. Three different aspects screen events not applicable to SBK.

relate to this issue:

Events 1.a. LOOP Initiating Event Frequency were categorized into three event types 1 b. Conditional LOOP Frequency (plant-centered, grid-related, and weather-induced) for which OSP recovery was 1c. Availability of DC power to perform considered separately.

restoration actions The approach used for LOOP frequencies was consistent with the current industry approach. Therefore, no modeling uncertainties were introduced, and a sensitivity analysis was not required for this LAR.

Conditional LOOP was modeled in the SBK model for Rx trip and LOCA initiators. The conditional LOOP probability was based on a review of industry data.

The approach used for considering conditional LOOP events and DC power availability for power restoration was generally consistent with industry practice.

Therefore, no modeling uncertainties were introduced relative to risk-informed applications and no sensitivity analysis was required for this LAR.

Station Blackout events are important This assumption added a small amount of contributors to baseline CDF at nearly conservatism to the base PRA results.

every U.S. nuclear power plant. In many cases, battery depletion may be This was a conservative assumption; assumed to lead to loss of all system therefore, no sensitivity analysis was capability.

required for this LAR.

Station Blackout events are important Battery depletion time was assumed to be contributors to baseline CDF at nearly the design value of 4 hours4.62963e-5 days 0.00111 hours 6.613757e-6 weeks 1.522e-6 months with no load every U.S. nuclear power plant. Battery shedding. However, with credit for load life is an important factor in assessing a management, the battery depletion time plant's ability to cope with a Station was 12 hours1.388889e-4 days 0.00333 hours 1.984127e-5 weeks 4.566e-6 months ; therefore, the battery life Blackout. Many plants only have model was judged realistic. After 12 hours1.388889e-4 days 0.00333 hours 1.984127e-5 weeks 4.566e-6 months , design basis calculations for battery life.

the batteries are assumed failed.

Other plants have very plant/condition specific calculations of batterv life.

Seabrook Station Docket Nos. 50-443 ABLB RAl-2 Failing to fully credit battery capability can overstate risks, and mask other potential contributors and insights.

Realistically assessing battery life can be complex.

SBK-L-22024 Enclosure Page 3of19 This assumption was validated by the Seabrook Design Engineering calculations.

Seabrook Design Engineering calculations verified the 4-hour battery depletion with no load shed and 12-hour battery depletion assumption when load shed was successful. Credit for extended battery life was consistent with industry practice, does not represent a significant source of uncertainty, and did not require a sensitivity analysis for this LAR.

A stand-alone bounding calculation was used to determine the potential impact of the fire events for the proposed extension. Clarify whether the resulting total site fire frequency used in this assessment will also be used as the baseline risk metric in future full power fire PRA applications. Alternatively, describe how this permanent change will be incorporated into the fire PRA.

NextEra Response to ABLB RAI - 2 The stand-alone total bounding calculation was performed for the proposed AOT increase from 24 hours2.777778e-4 days 0.00667 hours 3.968254e-5 weeks 9.132e-6 months to 7 days for an inoperable 120 VAC vital instrument panel inverter. NextEra does not intend to use the total site frequency for other future applications. The specific calculation was done to determine the delta risk for the proposed AOT increase. Any future applications will evaluate the Fire PRA risk for that specific application. Since this was a delta risk calculation, a permanent change to Fire PRA is not applicable for any other application.

EEEB RAl-1 The licensee proposed to revise Seabrook TS 3.8.3.1, ACTION b, by increasing from 24 hours2.777778e-4 days 0.00667 hours 3.968254e-5 weeks 9.132e-6 months to 7 days the AOT to reenergize 120 VAC Vital Instrument Panels 1A, 1B1 C, 1 D, 1 E or 1 F from its associated inverter connected to its associated DC bus.

The staff notes that the LAR did not provide a deterministic justification for the proposed 7-day AOT.

Provide a technical justification for the proposed 7-day AOT extension (actual hours plus margin) based on plant-specific past operating experience and vendor recommendations.

NextEra Response to EEEB RAI - 1 In Reference 3, as supplemented by Reference 4, NextEra requested an increase in the Allowable Outage Time (AOT), aka Completion Time, of TS 3.8.3.1, ACTION b, from 24-hours to 7-days for 120 VAC vital instrument panel inverters 1A, 1 B, 1 C, 1 D, 1 E, and 1 F. As stated in Reference 3, and as supported by the precedents described in Sections 4.2.3, 4.2.4 and 4.2.5 therein, industry experience has shown that the current 24-hour AOT for restoration of an inoperable vital instrument bus inverter, the typical cause of 120 VAC vital instrument panel inoperability, is insufficient to support troubleshooting and restorative maintenance while the unit is on line. Reference 3 further explains that when a vital instrument bus inverter becomes inoperable, the on-line work management process must first determine and implement risk-based measures which minimize potential impacts of the inoperability on safety such as establishing barrier postings for guarded equipment and rescheduling planned surveillances. Proper electrical safety system tagging must also be performed before troubleshooting activities such as physical inspection of the uninterrupted power supply (UPS) panels

Seabrook Station Docket Nos. 50-443 SBK-L-22024 Enclosure Page 4of19 and fuses, and alarm checks can begin. Replacement components may not be readily available and, in the case of replacement circuit cards, may require burn-in periods exceeding the 24-hour AOT.

Following repair, post-maintenance testing can include lengthy inverter functional testing. For these reasons, a one-time AOT extension amendment request and a Notice of Enforcement Discretion (NOED) are typically prepared in parallel with the maintenance planning and repair. In Reference 5, NextEra was granted a NOED in order to avert a unit shutdown for an inoperable 1 E vital instrument panel inverter.

The justification for the proposed AOT from 24 hours2.777778e-4 days 0.00667 hours 3.968254e-5 weeks 9.132e-6 months to 7 days for the 120 VAC vital instrument panel inverters is that it would avoid unplanned plant shutdowns where the risks incurred can exceed those associated with continued power operation. The proposed AOT extension would provide sufficient time for orderly determination of risk-based measures in accordance with the Seabrook configuration risk management program (CRMP), the deployment of a round-the-clock, multi-discipline troubleshooting team, as well as the development and implementation of a troubleshooting plan, work order packages, maintenance repair and replacement (if necessary) of faulty subcomponents, post-maintenance testing, and system/train restoration. The postulated timeline for an inoperable vital instrument panel inverter provided below demonstrates that restoration can take well in excess of the current 24-hour AOT.

Possibly 2 to 3 days additional could be required if the restoration requires the replacement of multiple failed components due to a short-circuit or the replacement of cards for which burned-in spares are not readily available.

Approximate Plant Activity Duration (hours)

Assemble troubleshooting team 4

Staff the Operations Control Center (OCC) 4 Tag out equipment 4

Develop complex troubleshooting plan 12 Plan troubleshooting work order(s) 4 Execution of troubleshooting work order(s) 12 Plan corrective maintenance work order(s) 4 Perform corrective maintenance 48 Post Maintenance testing 12 Clear tags 4

Align and start inverter 2

Preventive maintenance performed on the 120 VAC vital instrument panel UPS(s), including the inverters, involves inspection of the cabinets for cleanliness and evidence of electrical overheating, burned rectifiers, leaking capacitors, pitted contacts, and deteriorated insulation. UPS preventive maintenance additionally includes testing of the various relay boards, inverter static switch testing, reverse polarity testing, etc. These activities are performed during refueling outages to avoid unnecessary challenges to unit operation as a result of the current 24-hour inverter AOT. The proposed AOT extension from 24 hours2.777778e-4 days 0.00667 hours 3.968254e-5 weeks 9.132e-6 months to 7 days would provide increased flexibility in the scheduling and performance of required and elective vital instrument inverter maintenance with the unit on-line. Should elective maintenance on a 120 VAC vital instrument panel inverter be pursued during power operation, the following compensatory measures will be implemented prior to entry into the proposed 7-day AOT:

1.

Entry into the proposed 7-day AOT will not be planned concurrent with planned emergency diesel generator (EOG) maintenance.

2.

Entry into the proposed 7-day AOT will not be planned concurrent with planned maintenance on another RPS or ESFAS channel that could result in that channel being in a tripped condition.

Seabrook Station Docket Nos. 50-443 SBK-L-22024 Enclosure Page 5of19 To assure appropriate regulatory control over the above measures, the compensatory measures are being included in the TS Bases, whereby proposed changes will be subject to 10 CFR 50.59. to this RAI response provides the revised TS Bases markup pages as discussed. The revised TS Bases markup pages supersede the corresponding pages provided in References 3 and 4.

The TS Bases changes are provided for information only and will be incorporated in accordance with TS Bases Control Program upon implementation of the approved amendments.

EEEB RAI -2 The licensee proposed a new TS 3.8.3.1, ACTION d, for the condition of two 120 VAC vital instrument panels of the same electrical train either not energized from their associated inverter or with their inverters not connected to their associated DC bus (i.e., inoperable). The proposed completion time for restoring at least one AC vital panel from its associated inverter connected to its associated DC bus is within 8 hours9.259259e-5 days 0.00222 hours 1.322751e-5 weeks 3.044e-6 months .

The licensee proposed a new TS 3.8.3.1, ACTION d, as follows:

With two AC. vital panels of the same electrical train either not energized from their associated inverter, or with their inverters not connected to their associated D.C. bus: (1) reenergize both AC. vital panels within 2 hours2.314815e-5 days 5.555556e-4 hours 3.306878e-6 weeks 7.61e-7 months or be in at least HOT STANDBY within the next 6 hours6.944444e-5 days 0.00167 hours 9.920635e-6 weeks 2.283e-6 months and in COLD SHUTDOWN within the following 30 hours3.472222e-4 days 0.00833 hours 4.960317e-5 weeks 1.1415e-5 months ; and (2) reenergize at least one AC. vital panel from its associated inverter connected to its associated D.C. bus within 8 hours9.259259e-5 days 0.00222 hours 1.322751e-5 weeks 3.044e-6 months or be in at least HOT STANDBY within the next 6 hours6.944444e-5 days 0.00167 hours 9.920635e-6 weeks 2.283e-6 months and in COLD SHUTDOWN within the following 30 hours3.472222e-4 days 0.00833 hours 4.960317e-5 weeks 1.1415e-5 months .

The staff notes the following:

A footnote to the LCO 3.8.3.1 denoted by the asterisk next to the DC Bus numbering allows two inverters to be disconnected from their DC bus for the purpose of performing an equalizing charge on their associated battery bank. Thus, the proposed new Action d would apply when two inverters in the same train are not connected to their associated DC supply for reasons other than "performing an equalizing charge on their associated battery bank."

Seabrook TS LCO 3.8.3.1 requires the AC vital panels to be energized from their associated inverters.

In the proposed new Action d.2, it appears that one of the AC vital panels would not to be reenergized from its associated inverter connected to its associated DC bus. This would result in the proposed new Action d not meeting the LCO. The licensee would have to enter LCO 3.0.3 to shut down the reactor for two inoperable AC vital panels of the same train in the proposed new Action d, as it would be the case under the current TS 3.8.3.1.

The LAR did not appear to provide a plant-specific justification for the 8-hour AOT proposed for the new Action d.

The NRG staff has the following questions:

a) Clarify if the proposed Action d will apply to all three vital AC panels/inverters of the same electrical train.

b) Discuss how the proposed new Action d meet the LCO 3.8.3.1 requirements for the 120-volt AC vital panels in accordance with 10 CFR 50.36(c)(2)(i).

c)

Provide a technical justification for the proposed 8-hour AOT for two inoperable inverters in the new Action d based on plant-specific past operating experience and/or timeline for reenergizing an AC vital panel from its associated inverter connected to its associated DC bus.

Seabrook Station Docket Nos. 50-443 NextEra Response to EEEB RAI - 2(a)

SBK-L-22024 Enclosure Page 6of19 NextEra has revised proposed ACTION d to address the condition of two or more inoperable vital AC panels/inverters of the same electrical train. This is a change from the ACTION d proposed in References 3 and 4 in order to accommodate the application of ACTION d to all three vital AC panels and associated inverters of the same electrical train. The revised ACTION d proposed in this RAI response requires that within 2 hours2.314815e-5 days 5.555556e-4 hours 3.306878e-6 weeks 7.61e-7 months , all three vital instrument panels are reenergized or verified to be energized, and within 8 hours9.259259e-5 days 0.00222 hours 1.322751e-5 weeks 3.044e-6 months , at least two vital instrument panels are reenergized or verified to be energized from their associated inverters connected to their associated DC busses. The revised ACTION d now differs from the precedents described in Sections 4.2.1 and 4.2.2 of Reference 3 in its applicability to three 120 VAC vital instrument panels per electrical train, though the 1E (train A) and 1 F (train B) vital instrument panels primarily support BOP functions.

In contrast, the referenced licensees have but two TS-specified 120 VAC vital instrument panels per electrical train. However, the applicability of these precedents to the proposed ACTION d of this RAI response remain valid with regard to the capability of the remaining train of 120 VAC vital instrument panels/inverters to support the minimum safety functions necessary to shut down the reactor and maintain it in a safe condition, assuming no single failure. The table below summarizes the ACTIONS and associated AOTs for each electrical train of 120 VAC vital instrument panels that would be impacted by any combination of inoperable vital instrument panels of the same electrical train. A revision is also proposed to the TS Bases which clarifies that ACTION d does not apply to the footnote to LCO 3.8.3.1 which allows two inverters to be disconnected from their D.C. bus up to 24 hours2.777778e-4 days 0.00667 hours 3.968254e-5 weeks 9.132e-6 months for the purpose of performing an equalizing charge on their associated battery bank, consistent with the Staff's understanding expressed in EEEB RAl-2 above. The proposed TS Bases will also clarify that upon exiting ACTION d and entering ACTION b for the remaining inoperable inverter, the proposed 7-day AOT of ACTION b begins at the time of initial inoperability (rather upon exiting ACTION d). Attachment 1 to this RAI response provides the revised TS markup pages including the revision to the proposed ACTION d as discussed. provides the revised TS Bases markup pages as discussed. The revised TS and TS Bases markup pages supersede the corresponding pages provided in References 3 and 4. The TS Bases changes are provided for information only and will be incorporated in accordance with TS Bases Control Program upon implementation of the approved amendments.

Inoperable 120 VAC Vital Instrument Panel ACTIONS and AOT Combinations Inoperable Applicable Applicable 120 VAC Vital TS ACTION Required Action AOT Instrument Panels Reenergize inoperable panel 2 hours2.314815e-5 days 5.555556e-4 hours 3.306878e-6 weeks 7.61e-7 months 1A or 1C or 1 E ACTION b Restore inoperable inverter 7 days (Proposed)

TRAIN Reenergize panels 1A and 1 C 2 hours2.314815e-5 days 5.555556e-4 hours 3.306878e-6 weeks 7.61e-7 months ACTION d A

1Aand 1C (Proposed)

Restore inverter 1 A or 1 C 8 hours9.259259e-5 days 0.00222 hours 1.322751e-5 weeks 3.044e-6 months and enter ACTION b Reenergize panels 1A and 1 E 2 hours2.314815e-5 days 5.555556e-4 hours 3.306878e-6 weeks 7.61e-7 months 1A and 1E ACTION d (Proposed)

Restore inverter 1A or 1 E 8 hours9.259259e-5 days 0.00222 hours 1.322751e-5 weeks 3.044e-6 months and enter ACTION b 1C and 1E ACTION d Reenergize panels 1 C and 1 E 2 hours2.314815e-5 days 5.555556e-4 hours 3.306878e-6 weeks 7.61e-7 months (Proposed)

Seabrook Station Docket Nos. 50-443 1A, 1C and 1E 18 or 1Dor1 F 18 and 1D TRAIN 18 and 1F 8

1D and 1F 18, 10 and 1F ACTION d (Proposed)

ACTION b ACTION d (Proposed)

ACTION d (Proposed)

NextEra Response to EEEB RAI - 2(b)

Restore inverter 1 C or 1 E and enter ACTION b Reenergize panels 1A, 1C and 1E Restore any two inverters and enter ACTION b Reenergize inoperable panel Restore inoperable inverter Reenergize panels 18 and 1 D Restore inverter 1 8 or 1 D and enter ACTION b Reenergize panels 18 and 1 F Restore inverter 18 or 1 F and enter ACTION b Reenergize panels 1 D and 1 F Restore inverter 1 D or 1 F and enter ACTION b Reenergize panels 18, 10 and 1F Restore any two inverters and enter ACTION b S8K-L-22024 Enclosure Page 7of19 8 hours9.259259e-5 days 0.00222 hours 1.322751e-5 weeks 3.044e-6 months 2 hours 8 hours9.259259e-5 days 0.00222 hours 1.322751e-5 weeks 3.044e-6 months 2 hours 7 days (Proposed) 2 hours2.314815e-5 days 5.555556e-4 hours 3.306878e-6 weeks 7.61e-7 months 8 hours 2 hours2.314815e-5 days 5.555556e-4 hours 3.306878e-6 weeks 7.61e-7 months 8 hours 2 hours2.314815e-5 days 5.555556e-4 hours 3.306878e-6 weeks 7.61e-7 months 8 hours 2 hours2.314815e-5 days 5.555556e-4 hours 3.306878e-6 weeks 7.61e-7 months 8 hours The revised new ACTION d provided in this RAI response addresses the condition of two or more 120-volt AC vital instrument panels of the same electrical train either not energized from their associated inverters or with their inverters not connected to their associated DC busses i.e. inoperable. The requested change is a consequence of the current Seabrook TS, which does not allow the 120 VAC vital instrument panels to be considered operable whenever the DC link to their associated inverters are disrupted despite being energized and fully capable of powering their supported equipment.

As it relates to this amendment request, the relevant portion of 10 CFR 50.36(c)(2)(i) states that when a limiting condition for operation of a nuclear reactor is not met, the licensee shall shut down the reactor or follow any remedial action permitted by the technical specifications until the condition can be met.

Under current TS 3.8.3.1, the unit must shutdown in accordance with LCO 3.0.3 for the condition of two vital instrument panels of the same electrical train inoperable since no TS ACTION exists for more than one inoperable vital instrument panel. NextEra believes that an immediate unit shutdown does not align with the safety significance of the condition addressed in proposed ACTION d. Specifically, in the event of two or more vital panel/inverter failures on the same electrical train due to the inoperability of the DC links to their associated inverters, the most likely scenario for the application of proposed ACTION d, the instrument panels would either remain energized from their normal inverter-powered Class 1 E qualified 480-volt MCCs or 125 VDC bus, or if power to the instrument panels were disrupted,

Seabrook Station Docket Nos. 50-443 SBK-L-22024 Enclosure Page 8of19 their associated static transfer switches would shift power to their backup (aka maintenance) MCC power supplies, just as the case for a single inverter failure, and operating procedures direct manual transfer to the backup AC power supplies if required. In the case of vital instrument panel 1-EDE-PP-1 D, which has not yet been equipped with an integral static transfer switch for automatic and fast transfer to its maintenance power supply, a procedurally controlled manual transfer would be required which would be accomplished well within the 2-hour AOT proposed in ACTION d. The backup MCCs are non-safety related but are maintained as fully qualified Class 1 E in accordance with station procedures to assure reliable backup power is available to the vital instrument panels. If upon loss of offsite power during the proposed 8-hour AOT for the instrument panel inverters, the vital instrument panels would be momentarily deenergized (-12 seconds) before the Class 1E qualified MCCs would be repowered by the EOG associated with the affected electrical train or by their respective maintenance supply MCCs, which are also EOG-backed. Moreover, the inoperability of two or more vital instrument panels/inverters of the same train would not place the unit outside of its design basis since the redundant set of instrument panels/inverters on the opposite train are available to support the minimum safety functions necessary to shut down and maintain the reactor in a safe shutdown condition assuming no single failure.. Thereby, the safety implications of immediate LCO 3.0.3 entry for two or more inoperable inverters of the same electrical train if ACTION d were not available outweigh the proposed 8-hour AOT to restore at least one inverter while the affected instrument panels are powered from their respective normal or maintenance supplies. For this reason, NextEra believes the remedial action of implementing proposed ACTION d in lieu of a reactor shutdown better serves the LCO 3.8.3.1 requirements in accordance with 10 CFR 50.36(c)(2)(i) for the 120 VAC vital instrument panels NextEra Response to EEEB RAI - 2(c)

The application of the proposed ACTION d provided in this RAI response is most likely to occur if it became necessary to reenergize one or more vital instrument panels while already in ACTION b for a single inoperable inverter (with the affected vital instrument panel reenergized) or to restore the 125 VDC links to one or more vital instrument inverters while in ACTION b for a single inoperable inverter.

In the former circumstance, either the associated static switches would immediately repower the affected instrument panels from the dedicated backup AC power supply or, in the case of vital instrument panel 1-EDE-PP-1 D, a procedurally controlled manual transfer to its dedicated backup AC power supply would be necessary but would occur well within the two hours allotted by proposed ACTION d. In the latter circumstance, normal Class 1E480-volt MCC power to the affected instrument panels would not have been interrupted (unless for pre-planned electrical tag outs in preparation for maintenance). Following reenergization of the affected vital panels, 8-hours from the initial inoperability of two or more vital instrument panels would be available to restore at least one inoperable inverter and exit proposed ACTION d before a unit shutdown would be required.

For the reasons discussed in the response to EEEB RAl-1, operating experience has shown that the restoration of at least one inverter within the 8-hour AOT of proposed ACTION d is unlikely. More likely, the 8-hours would be used to re-validate the condition of the more recent inoperable inverter, initiate staffing of a troubleshooting team and the Operations Control Center (OCC) and implement risk-based actions which serve to minimize the effect of the inoperability on plant safety and the potential for a loss of power to the remaining train of 120 VAC vital instrument panels. Compounding these important plant activities would be the initiation of a unit shutdown within the one-hour required by LCO 3.0.3. The proposed 8-hour AOT is consistent with TS 3.8.3.1, ACTION A, which allows 8 hours9.259259e-5 days 0.00222 hours 1.322751e-5 weeks 3.044e-6 months to restore a not fully energized AC emergency bus train, a condition which would render inoperable one electrical train of 120 VAC vital instrument panels. The proposed 8-hour AOT is also consistent with Standard Technical Specifications (STS) 3.8.9, ACTION A, of NUREG 1431 (Reference 6), for an inoperable AC electrical power distribution subsystem, of which the STS Bases 3.8.9, ACTION A (Reference 7) states that the 8-hour time limit before requiring a unit shutdown is acceptable because of:

a.

The potential for decreased safety if the unit operator's attention is diverted from the evaluations and actions necessary to restore power to the affected train, to the actions associated with taking the unit to shutdown within this time limit, and

Seabrook Station Docket Nos. 50-443 SBK-L-22024 Enclosure Page 9of19

b.

The potential for an event in conjunction with a single failure of a redundant component in the train with AC power.

For the above reasons, NextEra believes there is sufficient justification for an 8-hour AOT to address the condition of two or more inoperable vital instrument panel inverters as proposed for ACTION d in this RAJ response.

EEEB RAI - 3 The licensee stated that the enclosure and attachments provided in its supplement dated September 22, 2021, superseded and replaced the corresponding enclosure and attachments of its initial application dated July 21, 2021. Attachment 1, "Proposed Technical Specification Pages (Markup)," to the enclosure provides revised Seabrook TS pages marked up to show the proposed changes.

The staff notes that Attachment 1 does not show all the proposed changes.

Provide a markup to the TS that shows the proposed 1) deletion of 24 hours2.777778e-4 days 0.00667 hours 3.968254e-5 weeks 9.132e-6 months AOT with the associated asterisk and footnote and 2) the proposed 7-day AOT.

NextEra Response to EEEB RAI - 3 NextEra acknowledges that the red-lined mark-up to the TS and TS Bases pages provided in Reference 3 did not survive electronic submittal to the NRC Document Control Desk and as a result, the proposed changes were not reflected in the TS and TS Bases markup pages. Attachment 1 to this RAJ response provides the existing TS pages marked up to show the proposed changes. Attachment 2 provides the existing TS Bases pages marked up to show the proposed changes. The TS and TS Bases marked up pages supersede the corresponding pages provided in References 3 and 4. The TS Bases changes are provided for information only and will be incorporated in accordance with the TS Bases Control Program upon implementation of the approved license amendments.

EEEB RAI -4 Section 2.1 of the LAR states:

Should a UPS become unavailable, an alternate supply is available by an automatic/manual transfer switch for 120 VAC instrument busses 1 A, 1 B, 1 E and 1 F...

For balance-of-plant UPS units 1E and 1F (1-EDE-l-1E and 1-EDE-l-1F), power transfer from the associated instrument bus inverters to the maintenance supply can be automatic or manual without interruption to the connecting loads.

The 120 VAC Vital Instrument System inverters I-EDE-I-IE and I-EDE-I-IF associated with instrument buses IE and IF supply power to balance-of-plant instrumentation. UPS IE, designated for the "A" train, and UPS IF, for the "B" train, derive their AC and DC input power from train "A" and train "B" safety-related power supplies. Each of the two balance of-plant vital instrument buses are provided with a static transfer switch for automatic, fast transfer of these buses to a maintenance supply from a 480/120-volt AC transformer connected to a non-safety-related power source (with a backup power supply from the emergency diesel generator) in the event of unavailability of the associated UPS.

The staff notes that the names of the balance of plant vital instrument buses and associated UPSs and inverters are not consistent within the LAR.

Seabrook Station Docket Nos. 50-443 SBK-L-22024 Enclosure Page10of19 Clarify the names and/or designation of the UPSs, inverters, and vital instrument buses associated with the balance of plant Train A and Train B vital instrument panels.

NextEra Response to EEEB RAI - 4 NextEra acknowledges that in some areas of References 3 and 4, the equipment numbers for the 1 E and 1 F 120 VAC instrument panel inverters were inadvertently referred to as I-EDE-I-IE and 1-EDE IF in lieu of 1-EDE-1-1E and 1-EDE-l-1F, with the correction being in bold-font to emphasize the distinction. The table below provides the designated equipment titles and equipment numbers for the 120 VAC instrument inverters and vital instrument buses. The listed plant drawing equipment tag numbers were employed for this amendment request. In general, the UPS and inverter terms are used synonymously though the UPS consists of the rectifier, inverter, and the integral transfer switch for the 120 VAC maintenance/bypass supply. Similarly, the terms 120 VAC vital instrument 'power panel' and 120 VAC vital instrument 'bus' are often used interchangeably.

Equipment Name Electrical Plant Drawing Plant Database Train Equipment Tag No.

Equipment Tag No.

Vital Inverter 1A A

1-EDE-1-1A 1-EDE-1-1-A Vital Inverter 1 B B

1-EDE-1-1 B 1-EDE-1-1-B Vital Inverter 1 C A

1-EDE-1-1 C 1-EDE-1-1-C Vital Inverter 1D B

1-EDE-1-10 1-EDE-1-1-D Vital Inverter 1 E A

1-EDE-l-1E 1-EDE-1-1-E Vital Inverter 1 F B

1-EDE-l-1F 1-EDE-1-1-F Vital AC Power Panel 1A A

1-EDE-PP-1A 1-EDE-PP-1-A Vital AC Power Panel 1 B B

1-EDE-PP-1 B 1-EDE-PP-1-B Vital AC Power Panel 1 C A

1-EDE-PP-1 C 1-EDE-PP-1-C Vital AC Power Panel 1 D B

1-EDE-PP-1 D 1-EDE-PP-1-D Vital AC Power Panel 1 E A

1-EDE-PP-1E 1-EDE-PP-1-E Vital AC Power Panel 1 F B

1-EDE-PP-1 F 1-EDE-PP-1-F

References:

1.

NRC electronic memorandum dated January 25, 2022, RE: Requests for Additional Information RE:

120 Inverter LAR from the Risk Branch, with attachment 'Requests for Additional Information Regarding the License Amendment Request to Revise Technical Specification 3/4.8.3, "Onsite Power Distribution - Operating" Seabrook Station, Unit No. 1, Docket No. 50-443'

2.

NRC electronic memorandum dated February 7, 2022, RE: Request for Additional Information RE: 120 Inverter LAR from the Electrical Branch, with attachment 'Requests for Additional Information Regarding the License Amendment Request to Revise Technical Specification 3/4.8.3, "Onsite Power Distribution - Operating" Seabrook Station, Unit No. 1, Docket No. 50-443'

3.

NextEra Energy Seabrook, LLC letter SBK-L-21067, License Amendment Request 21-01, Revise 120-Volt AC Vital Instrument Panel Requirements, July 21, 2021 (ADAMS Accession No. ML21202A238)

4.

NextEra Energy Seabrook, LLC letter SBK-L-21098, Supplement to License Amendment Request 21-01, Revise 120-Volt AC Vital Instrument Panel Requirements, September 22, 2021 (ADAMS Accession No. ML21265A416)

5.

Seabrook Station, Unit No. 1 - Issuance of Amendment No. 163 RE: One-Time Change to the Onsite Power Distribution Requirements (EPID L-2019-LLA-0216), December 5, 2019 (ADAMS Accession No. ML19326C480)

Seabrook Station Docket Nos. 50-443 SBK-L-22024 Enclosure Page 11 of 19

6.

NUREG-1431, Standard Technical Specifications, Westinghouse Plants, Revision 5.0, Volume 1, Specifications (ADAMS Accession No. ML21259A155)

7.

NUREG-1431, Standard Technical Specifications, Westinghouse Plants, Revision 5.0, Volume 1, Bases (ADAMS Accession No. ML21259A159)

Seabrook Station Docket No. 50-443 ATTACHMENT 1 PROPOSED TECHNICAL SPECIFICATION PAGES (MARKUP)

(3 pages follow)

SBK-L-22024 Enclosure Page12of19

!This page is for* information only. No changes are proposed for this page.

ELECTRICAL POWER SYSTEMS 3/4.8.3 ONSITE POWER DISTRIBUTION OPERATING LIMITING CONDITION FOR OPERATION 3.8.3.1 The following electrical busses shall be energized in the specified manner:

a.

Train A, A.C. Emergency Busses consisting of:

1) 4160-volt Emergency Bus #E5,

2) 480-volt Emergency Bus #E51,** and

3) 480-volt Emergency Bus #E52.**

b.

Train B, A.C. Emergency Susses Consisting of:

1) 4160-volt Emergency Bus #E6,

2) 480-volt Emergency Bus #E61,**

3) 480-volt Emergency Bus #E62,** and

4) 480-volt Emergency Bus #E64.

c.

120-volt A.C. Vital Panel #1A energized from its associated inverter connected to D.C. Bus #11A,*

d.

120-volt A.C. Vital Panel #1 B energized from its associated inverter connected to D.C. Bus #11 B,*

e.

120-volt A.C. Vital Panel #1 C energized from its associated inverter connected to D.C. Bus #11 C,*

f.

120-volt A.C. Vital Panel #1 D energized from its associated inverter connected to D.C. Bus #11 D,*

g.

120-volt A.C. Vital Panel #1 E energized from its associated inverter connected to D.C. Bus #11A,*

h.

120-volt A.C. Vital Panel #1 F energized from its associated inverter connected to D.C. Bus #11 B,*

Two inverters may be disconnected from their D.C. bus for up to 24 hours2.777778e-4 days 0.00667 hours 3.968254e-5 weeks 9.132e-6 months as necessary, for the purpose of performing an equalizing charge on their associated battery bank provided: (1) their vital busses are energized, and (2) the vital busses associated with the other battery bank are energized from their associated inverters and connected to their associated D.C. bus.

- These busses can be considered OPERABLE if the 480 volt bus ties are closed. These bus ties will be under administrative control to ensure loading is within transformer rating.

SEABROOK-UNIT 1 3/4 8-16

ELECTRICAL POWER SYSTEMS ONSITE POWER DISTRIBUTION OPERATING LIMITING CONDITION FOR OPERATION 3.8.3.1 (Continued)

i.

Train A, 125-volt D.C. Susses consisting of:

1)

2) 125-volt D.C. Bus 125-volt D.C. Bus

11 A energized from Battery Bank 1 A or 1 C, and

11 C energized from Battery Bank 1 C or 1 A.

j.

Train B, 125-volt D.C. Susses consisting of:

1) 125-volt D.C. Bus #11 B energized from Battery Bank 1 B or 1 D, and

2) 125-volt D.C. Bus #11 D energized from Battery Bank 1 D or 1 B.

APPLICABILITY: MODES 1, 2, 3, and 4.

ACTION:

NOTE--------------------------------------------------

Enter applicable ACTIONS of LCO 3.8.2.1, "DC Sources - Operating," for DC trains made inoperable by inoperable AC power distribution system.

a.

With one of the required trains of A.C. emergency busses (except 480-volt Emergency Bus# E64) not fully energized, reenergize the train within 8 hours9.259259e-5 days 0.00222 hours 1.322751e-5 weeks 3.044e-6 months or be in at least HOT STANDBY within the next 6 hours6.944444e-5 days 0.00167 hours 9.920635e-6 weeks 2.283e-6 months and in COLD SHUTDOWN within the following 30 hours3.472222e-4 days 0.00833 hours 4.960317e-5 weeks 1.1415e-5 months .

1.

With 480-volt Emergency bus #E64 not fully energized, reenergize the bus within 7 days or be in HOT STANDBY within 6 hours6.944444e-5 days 0.00167 hours 9.920635e-6 weeks 2.283e-6 months and COLD SHUTDOWN within the following 30 hours3.472222e-4 days 0.00833 hours 4.960317e-5 weeks 1.1415e-5 months .

b.

With one A.C. vital panel either not energized from its associated inverter, or with the inverter not connected to its associated D.C. bus: (1) reenergize the A.C. vital panel within 2 hours2.314815e-5 days 5.555556e-4 hours 3.306878e-6 weeks 7.61e-7 months or be in at least HOT STANDBY within the next 6 hours6.944444e-5 days 0.00167 hours 9.920635e-6 weeks 2.283e-6 months and in COLD SHUTDOWN within the following 30 hours3.472222e-4 days 0.00833 hours 4.960317e-5 weeks 1.1415e-5 months ; and (2) reenergize the A.C. vital panel from its associated inverter connected to its associated D.C. bus within 24* hours or

~

be in at least HOT STANDBY within the next 6 hours6.944444e-5 days 0.00167 hours 9.920635e-6 weeks 2.283e-6 months and in COLD SHUTDOWN't\\:. ~

within the following 30 hours3.472222e-4 days 0.00833 hours 4.960317e-5 weeks 1.1415e-5 months .

~

Insert new ACTION d.

(see next page)

c.

I

/

With one D.C. bus not energized from an OPERABLE battery bank, reenergize the D.C.

bus from an OPERABLE battery bank within 2 hours2.314815e-5 days 5.555556e-4 hours 3.306878e-6 weeks 7.61e-7 months or be in at least HOT STANDBY within the next 6 hours6.944444e-5 days 0.00167 hours 9.920635e-6 weeks 2.283e-6 months and in COLD SHUTDOWN within the following 30 hours3.472222e-4 days 0.00833 hours 4.960317e-5 weeks 1.1415e-5 months .

A eF1e til'l'le AOT exteF1sieF1 fer aF1 iMf)erable 120 'o'elt A. C. Vital Pa Rel #1 E allevvs 7 days to restore the iF111erter to OPERABLE status. Gol'l'lpensatory measures witl'lin ~JEE Letter SBI< L 19104 dated Octeber 3, 2019 will FeFl'laiFI iFI effect duriflg tl'le extefleleel AOT f)erieel. Tt'le eF1e til'l'le AOT exteF1sioF1 sl'lall expire 45 days after issuance of amendment.

t SEABROOK-UNIT 1 3/4 8-17 Amendment No. 48, 157,4-&1--463-

{'

INSERT New ACTION d.

~

or verify energized all...

d.

With two A.. vital panels of the same electrical train either not energized from their associated i erter, or with their inverters not connected to their associated D.C. bus: (1) reenergize eetfl.A.C. vital panels within 2 hours2.314815e-5 days 5.555556e-4 hours 3.306878e-6 weeks 7.61e-7 months or be in at least HOT STANDBY within the next 6 hours6.944444e-5 days 0.00167 hours 9.920635e-6 weeks 2.283e-6 months and in COLD SHUTDOWN within the following 30 hours3.472222e-4 days 0.00833 hours 4.960317e-5 weeks 1.1415e-5 months ; and (2) reenergize at least eAe A.G. vital panel from its associated inverter connected to its associated D.C. bus within 8 hours9.259259e-5 days 0.00222 hours 1.322751e-5 weeks 3.044e-6 months or be in at least HOT STANDBY within the next 6 hours6.944444e-5 days 0.00167 hours 9.920635e-6 weeks 2.283e-6 months and in COLD SHUTDOWN within the following 30 hours3.472222e-4 days 0.00833 hours 4.960317e-5 weeks 1.1415e-5 months .

or verify energized at least two A.C. vital panels from their associated inverters connected to their associated...

Seabrook Station Docket Nos. 50-443 ATTACHMENT 2 PROPOSED TECHNICAL SPECIFICATION BASES PAGES (MARKUP)

(3 pages follow)

SBK-L-22024 Enclosure Page16of19

!This page is for information only. No changes are proposed for this page.

ELECTRICAL POWER SYSTEMS BASES 3/4.8.3 ONSITE POWER DISTRIBUTION (continued)

APPLICABILITY The electrical power distribution subsystems are required to be OPERABLE in MODES 1, 2, 3, and 4 to ensure that:

Acceptable fuel design limits and reactor coolant pressure boundary limits are not exceeded, and Adequate core cooling is provided, and containment OPERABILITY and other vital functions are maintained in the event of a postulated OBA.

The AC and DC electrical power distribution subsystems required to be OPERABLE in MODES 5 and 6 provide assurance that:

Systems to provide adequate coolant inventory makeup are available for the irradiated fuel in the core, Systems needed to mitigate a fuel handling accident are available, Systems necessary to mitigate the effects of events that can lead to core damage during shutdown are available, and Instrumentation and control capability is available for monitoring and maintaining the unit in a cold shutdown and refueling condition.

ACTIONS MODES 1 through 4 With the OPERABLE electrical buses less than required by LCO 3.8.3.1 and without a loss of safety function, the remaining electrical power distribution subsystems are capable of supporting the minimum safety functions necessary to shut down the reactor and maintain it in a safe shutdown condition, assuming no single failure. The overall reliability is reduced, however, because a single failure in the remaining power distribution subsystems could result in the minimum required ESF functions not being supported.

When a required electrical bus is not energized, the associated loads, such as ESF components normally powered from the electrical bus, must also be declared inoperable.

ACTION a is modified by a Note that requires the applicable ACTIONS of LCO 3.8.2.1 "DC Sources -

Operating," be entered for DC trains made inoperable by inoperable power distribution subsystems. This is an exception to LCO 3.0.6 and ensures the proper actions are taken for these components.

lnoperability of a distribution system can result in loss of charging power to batteries and eventual loss of DC power. This Note ensures that the appropriate attention is given to restoring charging power to batteries, if necessary, after loss of distribution systems.

SEABROOK - UNIT 1 B 3/4 8-22 BC 04 15, 19-02

ELECTRICAL POWER SYSTEMS BASES 3/4.8.3 ONSITE POWER DISTRIBUTION (continued)

Add INSERT from next page ACTIONS (continued)

MODES 5 and 6 With less than the minimum required on-site power distribution systems sources, the action statement requires immediately suspending core alterations, positive reactivity changes, or movement of irradiated fuel. With respect to suspending positive reactivity changes, operations that individually add limited, positive reactivity are acceptable when, combined with other actions that add negative reactivity, the overall net reactivity addition is zero or negative. For example, a positive reactivity addition caused by temperature fluctuations from inventory addition or temperature control fluctuations is acceptable if it is combined with a negative reactivity addition such that the overall, net reactivity addition is zero or negative. Refer to TS Bases 3/4.9.1, Boron Concentration, for limits on boron concentration and water temperature for MODE 6 action statements involving suspension of positive reactivity changes.

SURVEILLANCE REQUIREMENTS Operability of the required electrical buses is confirmed by verifying correct breaker alignment and indicated voltage on the buses. The surveillance frequency is controlled under the Surveillance Frequency Control Program.

3/4.8.4 ELECTRICAL EQUIPMENT PROTECTIVE DEVICES Containment electrical penetrations are protected by deenergizing circuits not required during reactor operation. The OPERABILITY of the motor-operated valves thermal overload protection ensures that the thermal overload protection will not prevent safety-related valves from performing their function. The Surveillance Requirements for demonstrating the OPERABILITY of the thermal overload protection are in accordance with Regulatory Guide 1.106, "Thermal Overload Protection for Electric Motors on Motor Operated Valves," Revision 1, March 1977.

SEABROOK - UNIT 1 B 3/4 8-23 BC 04 15, 11 01, 14 05

TS Bases INSERT For 120 VAC vital instrument panels 1A, 18, 1C, 1D, 1E and 1F, ACTION b allows 7-days to restore an inoperable inverter provided the affected vital instrument panel is reenergized within 2-hours. If the affected vital instrument panel cannot be reenergized within 2-hours, the unit must be brought to at least MODE 3 within 6 hours6.944444e-5 days 0.00167 hours 9.920635e-6 weeks 2.283e-6 months and to MODE 5 within the following 30 hours3.472222e-4 days 0.00833 hours 4.960317e-5 weeks 1.1415e-5 months . The 7-days allotted to restore a 120 VAC vital panel inverter is based on engineering judgment taking into consideration the time required for inverter repair and the additional risk to which the unit is exposed due to the loss of redundancy in available electrical sources powering the affected 120 VAC vital instrument panel. If the inoperable inverter cannot be restored within 7 days, the unit must be brought to at least MODE 3 within 6 hours6.944444e-5 days 0.00167 hours 9.920635e-6 weeks 2.283e-6 months and to MODE 5 within the following 30 hours3.472222e-4 days 0.00833 hours 4.960317e-5 weeks 1.1415e-5 months .

Should elective maintenance on a 120 VAC vital instrument panel inverter be pursued during power operation, the following compensatory measures shall be implemented:

1. Entry into ACTION b will not be planned concurrent with planned emergency diesel generator (EOG) maintenance.

2. Entry into ACTION b will not be planned concurrent with planned maintenance on another RPS or ESFAS channel that could result in that channel being in a tripped condition.

For 120 VAC vital instrument panels 1A, 18, 1C, 1D, 1E and 1F, ACTION d allows 8-hours to restore two or more inoperable inverters of the same electrical train provided that all (three) vital instrument panels of the affected electrical train are reenergized or verified energized within 2-hours. If all vital instrument panels of the affected electrical train cannot be reenergized or verified energized within 2-hours, the unit must be brought to at least MODE 3 within 6 hours6.944444e-5 days 0.00167 hours 9.920635e-6 weeks 2.283e-6 months and to MODE 5 within the following 30 hours3.472222e-4 days 0.00833 hours 4.960317e-5 weeks 1.1415e-5 months . The inoperability of two or more vital instrument panels of the same electrical train would not place the unit outside of its design basis since the redundant instrument panels of the opposite electrical train remain available to support mitigation of any design basis accident. ACTION d requires at least two inverters to be reenergized or verified energized within 8 hours9.259259e-5 days 0.00222 hours 1.322751e-5 weeks 3.044e-6 months . If ACTION d is entered for two inoperable inverters, ACTION d can be exited upon restoration of one inoperable inverter and the presence of the other, operable inverter.

If ACTION d is entered for three inoperable inverters, ACTION d can be exited upon restoration of at least two inoperable inverters. Upon exiting ACTION d, ACTION b must then be entered for the remaining inverter, if inoperable, and the inverter must be restored within 7 days of its initial inoperability. The 8-hours allotted to reenergize or verified energized at least two inoperable inverters and exit ACTION d is reasonable given the reduction in electrical system reliability since a single failure in the redundant train could result in the minimum ESF functions not being supported. If at least two or more of the inoperable inverters cannot be reenergized or verified energized within 8-hours, the unit must be brought to at least MODE 3 within 6 hours6.944444e-5 days 0.00167 hours 9.920635e-6 weeks 2.283e-6 months and to MODE 5 within the following 30 hours3.472222e-4 days 0.00833 hours 4.960317e-5 weeks 1.1415e-5 months .

ACTION d does not apply to the footnote to LCOs 3.8.3.1.c through 3.8.3.1.h, whereby two inverters are disconnected from their D.C. bus for the purpose of performing an equalizing charge on their associated battery bank.

v t e Letter Sequence Response to RAI
EPID:L-2021-LLA-0131, Notice of Meeting with NextEra Energy Seabrook, LLC (Approved, Closed)
Initiation Request, Request Acceptance, Acceptance Supplement Administration Questions 7 February 2022 25 January 2022 31 May 2022 Answers 27 June 2022 7 March 2022 Results Approval Other:
MONTHYEAR2022-01-25 [Table View]

SBK-L-22024, Response to Request for Additional Information (Raj) Regarding License Amendment Request 21-01, Revise 120-Volt AC Vital Instrument Panel Requirements

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References:

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SBK-L-22024, Response to Request for Additional Information (Raj) Regarding License Amendment Request 21-01, Revise 120-Volt AC Vital Instrument Panel Requirements

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