ML20258A150

Request for Additional Information Related to Seabrook License Amendment Request Regarding One-Time Change to the AC Sources Operating TS

ML20258A150
Person / Time
Site:	Seabrook
Issue date:	09/14/2020
From:	Justin Poole Plant Licensing Branch 1
To:	Browne K, Greene J, Moul D NextEra Energy Seabrook
Poole J, NRR/DORL/LPLI, 415-2048
References
EPID L-2020-LLA-0157
Download: ML20258A150 (5)

Text

From: Poole, Justin To: Browne, Kenneth; Greene, Joshua Cc: Danna, James; Rowley, Jonathan

Subject:

Request for Additional Information Related to Seabrook License Amendment Request Regarding One-Time Change to the AC Sources Operating TS (EPID L-2020-LLA-0157)

Date: Monday, September 14, 2020 10:35:00 AM Attachments: L-2020-LLA-0157 RAIs.pdf Ken/Josh, By letter dated July 13, 2020 (Agencywide Documents Access and Management System (ADAMS) Accession No. ML20196L772), NextEra Energy Seabrook, LLC (NextEra, the licensee) submitted a license amendment request (LAR) to revise the TS 3/4.8.1, A.C.

[Alternating Current] - Operating, for Seabrook Station, Unit No. 1. Specifically, the LAR would extend the allowed outage time (AOT) for one emergency diesel generator (EDG) inoperable from 14 days to 30 days on a one-time basis. The proposed change will allow the licensee to perform planned maintenance on the B EDG while at-power. In reviewing the submitted information, the U.S. Nuclear Regulatory Commission (NRC) staff has determined that additional information is necessary to complete its review.

On August 25, 2020, the NRC staff sent NextEra the DRAFT RAIs to ensure that the questions are understandable, the regulatory basis is clear, there is no proprietary information contained in the RAI, and to determine if the information was previously docketed. On September 10, 2020, the NRC and NextEra held a clarifying call. During the call, NextEra requested a response date of 30 days from the date of the DRAFT RAI email.

The NRC staff informed NextEra that providing the RAI response as soon as possible would help the staff meet the licensees requested date of October 31, 2020, for completing the review. NextEra understood. The attached is the final version of the RAIs. These RAIs will be put in ADAMS as a publicly available document.

Justin C. Poole Project Manager NRR/DORL/LPL I U.S. Nuclear Regulatory Commission (301)415-2048

REQUEST FOR ADDITIONAL INFORMATION REGARDING TECHNICAL SPECIFICATION 3/4.8.1 FOR A ONE-TIME EXTENSION OF ALLOWED OUTAGE TIME NEXTERA ENERGY SEABROOK, LLC SEABROOK STATION, UNIT NO. 1 DOCKET NO. 50-443 By letter dated July 13, 2020 (Agencywide Documents Access and Management System (ADAMS) Accession number ML20196L772), NextEra Energy Seabrook, LLC (NextEra, the licensee), requested an amendment to Seabrook Station (Seabrook) Technical Specifications (TS). The proposed license amendment request (LAR) revises the Seabrook TS 3/4.8.1, A.C.

[Alternating Current] - Operating, to extend the allowed outage time (AOT) for one emergency diesel generator (EDG) inoperable from 14 days to 30 days on a one-time basis. The proposed change will allow the licensee to perform planned maintenance on the B EDG while at-power.

Regulatory Requirements and Guidance The NRC staff used following regulatory requirements to review the LAR:

Title 10 of the Code of Federal Regulations, Part 50 (10 CFR 50), Appendix A, General Design Criterion (GDC) 17, Electric power systems, states, in part:

An onsite electric power system and an offsite electric power system shall be provided to permit functioning of structures, systems, and components important to safety.

The onsite electric power supplies, including the batteries, and the onsite electric distribution system, shall have sufficient independence, redundancy, and testability to perform their safety functions assuming a single failure.

Provisions shall be included to minimize the probability of losing electric power from any of the remaining supplies as a result of, or coincident with, the loss of power generated by the nuclear power unit, the loss of power from the transmission network, or the loss of power from the onsite electric power supplies.

10 CFR 50.36, Technical specifications, requires, in part, that the applicants for a license authorizing operation of a production or utilization facility must include in their application proposed TSs. 10 CFR 50.36(c) requires that TS include items in five specific categories related to station operation. These categories are (1) Safety limits, limiting safety system settings, and limiting control settings, (2) Limiting conditions for operation (LCOs), (3) Surveillance requirements (SRs), (4) Design features, and (5) Administrative controls. The proposed change to the Seabrook TS relates to the LCO category.

The NRC staff used the following guidance documents for review of the LAR:

NUREG-0800, Branch Technical Position (BTP) 8-8, Onsite (Emergency Diesel Generators) and Offsite Power Sources Allowed Outage Time Extensions, dated February 2012 (ADAMS Accession No. ML113640138) provides guidance to the NRC staff in reviewing LARs proposing a one-time or permanent TS change to extend an EDG Allowed Outage Time (AOT) beyond 72 hours8.333333e-4 days <br />0.02 hours <br />1.190476e-4 weeks <br />2.7396e-5 months <br />.

The NRC staffs technical review of the LAR is guided by the criteria contained in the BTP. This document describes methods and compensatory measures that the staff finds acceptable for meeting the Commissions regulations when requesting extensions of allowed outage times; however, licensees may propose alternative approaches and/or deviations with proper technical justification.

NRC Staff Requests NUREG-0800, BTP 8-8, provides guidance, from a deterministic perspective, for reviewing a one-time CT extension request for onsite and offsite power sources. This document recommends a supplemental AC power source available for connection to station emergency buses to compensate for inoperable AC sources that are inoperable during extended AOTs to maintain defense-in-depth of electric power sources available to safely shutdown the plant in case of abnormal operating event, potential design basis event, or station blackout (SBO) event.

The proposed LAR requests a one-time extension of TS LCO 3.8.1.1, Action b(2)(a) AOT for an inoperable EDG from 14 days to 30 days if the Supplemental Emergency Power System (SEPS) is available. The LAR states that a non-safety related SEPS is available as a backup power source when one or both emergency diesel generators fail to start.

The LAR does not discuss the key criteria in BTP 8-8 to allow the staff to complete its review of the proposed 30-day AOT extension request for an inoperable EDG. The NRC staff requests the following additional information.

EEOB RAI - 1 BTP 8-8 states:

The supplemental source must have the capacity to bring a unit to safe shutdown (cold shutdown) in case of a loss of offsite power (LOOP) concurrent with a single failure during plant operation (Mode 1).

The LAR and Seabrook Updated Final Safety Analysis Report (UFSAR) Section 8.3, Onsite Power Systems, state that the SEPS can provide the required safety related loads in the event of a loss of offsite power (LOOP) coincident with the loss of one or both EDGs.

The NRC staff notes that although the SEPS can supply the safe shutdown during LOOP concurrent with the loss of one or both EDGs, the capability of the SEPS to bring the plant to a cold shutdown is not stated in the UFSAR or the LAR.

Clarify whether the SEPS has the capacity (including the required fuel oil) to bring the unit to cold shutdown in the event of a LOOP concurrent with a failure of EDG A, while EDG B is unavailable.

EEOB RAI - 2 BTP 8-8 states:

For plants using AAC or supplemental power sources discussed above, the time to make the AAC or supplemental power source available, including accomplishing the cross-connection, should be approximately one hour to enable restoration of battery chargers and control reactor coolant system inventory Seabrook UFSAR Section 8.3.1.2.b.1, Regulatory Guide 1.6 - Independence Between Redundant Standby Power Sources, states:

The Supplemental Emergency Power System (SEPS) uses a transfer switch that has the capability of connecting the non-safety related SEPS DGs to a safety related circuit breaker on either redundant load group.

The NRC staff notes that the time to make the SEPS available to power the safety buses is not discussed in the UFSAR or the LAR.

Provide the time it takes to make the SEPS available to supply power to the safety buses.

EEOB RAI - 3 BTP 8-8 states: The licensee must provide justification for the duration of the requested AOT (actual hours plus margin based on plant-specific past operating experience).

The LAR proposes a one-time EDG AOT extension from 14 to 30 days.

Provide details of the timeline of maintenance activities which provide justification for the requested 30-day AOT extension based on Seabrook past operating experience.

EEOB RAI - 4 BTP 8-8 states:

The TS must contain Required Actions and Completion Times to verify that the supplemental AC source is available before entering extended AOT. The availability of AAC or supplemental power source shall be checked every 8-12 hours (once per shift).

If the AAC or supplemental power source becomes unavailable any time during extended AOT, the unit shall enter the LCO and start shutting down within 24 hours2.777778e-4 days <br />0.00667 hours <br />3.968254e-5 weeks <br />9.132e-6 months <br />. This 24-hour period will be allowed only once within any given extended EDG AOT.

The LAR does not discuss the TS requirements for the availability and unavailability of SEPS during the requested extended AOT from 14 to 30 days.

Provide the TS required actions and completion times to verify the availability of the SEPS before entering the 30-day AOT, to check the availability of the SEPS once per shift during the extended 30-day AOT, and to shut down the unit within 24 hours2.777778e-4 days <br />0.00667 hours <br />3.968254e-5 weeks <br />9.132e-6 months <br /> if the SEPS becomes unavailable during the extended 30-day AOT.

EEOB RAI - 5 BTP 8-8 state:

The system load dispatcher will be contacted once per day to ensure no significant grid perturbations (high grid loading unable to withstand a single contingency of line or generation outage) are expected during the extended AOT.

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.

The LAR Section 3.2.1, Compensatory Actions, provides compensatory measures including the below measure during the proposed AOT extension.

Operations will coordinate with grid operators and request that conditions remain stable in accordance with Master/Local Control Center Procedure No. 1 (M/LCC 1) - Nuclear Plant Transmission Operations. The extended AOT interval will not be entered if Seabrook has been notified of entry into Master/Local Control Center Procedure No. 2 (M/LCC 2) -Abnormal Conditions Alert.

The NRC staff notes that the above proposed compensatory measure appears to be applicable before entering the extended AOT only.

The NRC staff requests the following:

Confirm that the above compensatory measure for coordination with grid operators will be performed once a day during the extended AOT to ensure that significant grid perturbations (high grid loading unable to withstand a single contingency of line or generation outage) will not be expected during the extended AOT. Otherwise, provide a justification for the selected frequency of coordination with grid operations during the extended AOT.