ML20260H476

NRR E-mail Capture - ANO-1 Final RAI License Amendment Request to Revise Lov Relay Allowable Values

ML20260H476
Person / Time
Site:	Arkansas Nuclear
Issue date:	09/09/2020
From:	Thomas Wengert NRC/NRR/DORL/LPL4
To:	Keele R Entergy Nuclear Operations
Wengert T
References
L-2019-LLA-0013
Download: ML20260H476 (6)

Text

From: Wengert, Thomas Sent: Wednesday, September 9, 2020 4:00 PM To: Keele Jr, Riley D Cc: BICE, DAVID B (ANO); Dixon-Herrity, Jennifer

Subject:

ANO-1 Final RAI RE: License Amendment Request to Revise LOV Relay Allowable Values (EPID L-2019-LLA-0013)

Attachments: Final RAI for ANO-1 LOV AV LAR.pdf On August 5, 2020, the U.S. Nuclear Regulatory Commission (NRC) staff sent Entergy Operations, Inc.

(the licensee) the draft Request for Additional Information (RAI) identified below. This RAI relates to the license amendment request to modify the current loss of voltage (LOV) relay allowable values contained in Technical Specification (TS) 3.3.8, Diesel Generator (DG) Loss of Power Start (LOPS) instrumentation, at Arkansas Nuclear One, Unit 1, as described below.

The NRC staff held a conference call with the licensee staff on August 10, 2020, to clarify this request. At the conclusion of the call, the NRC staff agreed to further clarify the request based on the discussions during the conference call. Attached is the revised, final RAI. As agreed, please provide a response to this RAI within 45 days of this correspondence. A publicly available version of this final RAI will be placed in the NRCs Agencywide Documents Access and Management System (ADAMS).

From: Wengert, Thomas Sent: Wednesday, August 05, 2020 1:28 PM To: Keele Jr, Riley D Cc: BICE, DAVID B (ANO) ; Dixon-Herrity, Jennifer

Subject:

ANO-1 Draft RAI RE: License Amendment Request to Revise LOV Relay Allowable Values (EPID L-2019-LLA-0013)

By application dated January 24, 2020 (Agencywide Documents Access and Management System (ADAMS) Accession No. ML20024E639), as supplemented by letter dated March 19, 2020 (ADAMS Accession No. ML20079K973), Entergy Operations, Inc. (Entergy, the licensee),

submitted a license amendment request (LAR) for Arkansas Nuclear One, Unit 1 (ANO-1). This LAR proposes a change to the current loss of voltage (LOV) relay allowable values contained in Technical Specification (TS) 3.3.8, Diesel Generator (DG) Loss of Power Start (LOPS) instrumentation.

The NRC staff has determined that additional information, as described in the attached request for additional information (RAI), is required for the staff to complete its review of this application. This RAI is identified as draft at this time to confirm your understanding of the information that the NRC staff needs to complete the evaluation. If the request for information is understood, please respond to this RAI within 30 days of the date of this request.

Please contact me if you would like to set up a conference call with the NRC staff to clarify this request for information.

Tom Wengert Project Manager - Arkansas Nuclear One NRR/DORL/LPL4

(301) 415-4037 Hearing Identifier: NRR_DRMA Email Number: 774 Mail Envelope Properties (DM6PR09MB4759D9F470F39454542FB6198F260)

Subject:

ANO-1 Final RAI RE: License Amendment Request to Revise LOV Relay Allowable Values (EPID L-2019-LLA-0013)

Sent Date: 9/9/2020 4:00:00 PM Received Date: 9/9/2020 4:00:00 PM From: Wengert, Thomas Created By: Thomas.Wengert@nrc.gov Recipients:

"BICE, DAVID B (ANO)" <DBICE@entergy.com>

Tracking Status: None "Dixon-Herrity, Jennifer" <Jennifer.Dixon-Herrity@nrc.gov>

Tracking Status: None "Keele Jr, Riley D" <rkeele@entergy.com>

Tracking Status: None Post Office: DM6PR09MB4759.namprd09.prod.outlook.com Files Size Date & Time MESSAGE 2478 9/9/2020 4:00:00 PM Final RAI for ANO-1 LOV AV LAR.pdf 117887 Options Priority: Normal Return Notification: No Reply Requested: No Sensitivity: Normal Expiration Date:

REQUEST FOR ADDITIONAL INFORMATION LICENSE AMENDMENT REQUEST TO REVISE LOSS OF VOLTAGE RELAY ALLOWABLE VALUES ENTERGY OPERATIONS, INC.

ARKANSAS NUCLEAR ONE, UNIT 1 DOCKET NO. 50-313 By application dated January 24, 2020 (Agencywide Documents Access and Management System (ADAMS) Accession No. ML20024E639), as supplemented by letter dated March 19, 2020 (ADAMS Accession No. ML20079K973), Entergy Operations, Inc. (Entergy, the licensee),

submitted a license amendment request (LAR) for Arkansas Nuclear One, Unit 1 (ANO-1). The licensee proposed a change to the current loss of voltage relay allowable values contained in Technical Specification (TS) 3.3.8, Diesel Generator (DG) Loss of Power Start (LOPS) instrumentation.

The U.S. Nuclear Regulatory Commission (NRC) staff has reviewed the information provided by the licensee in the LAR and has determined that additional information is required to complete its review, as described below.

Applicable Regulatory Requirements/Criteria ANO-1 was originally designed to comply with the 70 Atomic Energy Commission (AEC) proposed General Design Criteria for Nuclear Power Plant Construction Permits, published in July 1967.

For this review, the NRC staff used the elements of General Design Criterion (GDC) 17, Electric power systems, of Appendix A of Title 10 of the Code of Federal Regulations (10 CFR) Part 50, as described in ANO-1 Safety Analysis Report (SAR), Amendment 28 (ADAMS Accession No. ML18323A147), Section 8.3.1.2, related to conformance with GDC 17.

GDC 17 of Appendix A to 10 CFR 50, 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 safety function for each system (assuming the other system is not functioning) shall be to provide sufficient capacity and capability to assure that (1) specified acceptable fuel design limits and design conditions of the reactor coolant pressure boundary are not exceeded as a result of anticipated operational occurrences and (2) the core is cooled and containment integrity and other vital functions are maintained in the event of postulated accidents.

The regulation in 10 CFR 50.36(c)(3) Surveillance requirements, states: Surveillance requirements are requirements relating to test, calibration, or inspection to assure that the necessary quality of systems and components is maintained, that facility operation will be within safety limits, and that the limiting conditions for operation will be met.

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The proposed amendment would modify ANO-1 TS 3.3.8, Diesel Generator (DG) Loss of Power Start (LOPS). Specifically, the proposed amendment modifies the loss of voltage (LOV) relay allowable values stated in SR 3.3.8.2.b.

The NRC staff also used the information provided in References 2 and 3 of the LAR, as they pertain to the adequacy of voltages supplied to safety-related loads required to perform under anticipated operational occurrences and postulated accidents in conformance with the ANO-1 licensing basis and applicable regulatory requirements.

Applicable Regulatory Guidance Regulatory Issue Summary (RIS) 2011-12, Adequacy of Station Electric Distribution System Voltages, Revision 1 (ADAMS Accession No. ML113050583), clarifies voltage studies necessary for Degraded Voltage (DV) Relay (second level undervoltage protection) setting bases and Transmission Network/Offsite/Station electric power system design bases for meeting the regulatory requirements specified in GDC 17 to 10 CFR Part 50, Appendix A. For nuclear power plants that were licensed before GDC 17 applied, the updated final safety analysis report provides the applicable design criteria. In its application, the licensee stated that the plant modifications associated with the LAR are intended to address, in part, information contained in RIS 2011-12.

Background/Discussion As discussed in the LAR, SAR Section 8.3.1.2, related to conformance to GDC 17, and SAR section 8.3.1.5, Grid Undervoltage Protection (Millstone 2 and ANO Events), the current licensing basis of ANO-1 includes requirements for protection of safety-related equipment in the event of sustained degraded voltage conditions.

In the LAR, the licensee stated, The most recent offsite power grid study (completed in 2017) supports the assumption that sustained voltage degradation below the DV setpoint is not credible for the ANO-1 unit. The licensee further stated, Because the current ANO-1 design and licensing basis does not assume a sustained undervoltage condition as described above

[i.e., at a voltage below the current DV setpoint in the TSs], Entergy does not intend to include the new additional DV relays within the TSs. The relays will be controlled and tested, however, consistent with requirements for Class 1E devices.

ANO-1 SAR Section 8.3.1.5.1, NRC Positions/ANO Responses, Position 1, Second Level of Under- or Over-Voltage Protection With a Time Delay, describes requirements for a second level of voltage protection for the onsite power system. Position 1, item C.3 states, The allowable time duration of a degraded voltage condition at all distribution system levels should not result in failure of safety systems or components.

In the LAR, the licensee stated, The MSP [motor start protection] relays will be set at a slightly lower voltage than the DV relays and will ensure that 480 V motor voltage is maintained above the 80% start voltage. No change is proposed for the existing DV relays or associated TS allowable voltage and time delay values. The licensee further stated that reducing the time delay of the existing DVRs could increase the potential of inadvertent separation from operable offsite power sources. The licensee noted that this would be contrary to the intent of RIS 2011-12.

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Request for Additional Information (RAI)

RAI EEOB-1 The existing DV and LOV relays perform certain safety functions and, in conformance with requirements of 10 CFR 50.36, are included in TS 3.3.8, Diesel Generator (DG) Loss of Power Start (LOPS). In the LAR, the licensee provided an overview of the functions of the MSP relays.

In order to understand all the safety functions performed by MSP relays in combination with DV and LOV relays for conformance with requirements of GDC 17, the NRC staff is requesting additional information. Specifically, the information in the LAR does not make it sufficiently clear that the protection afforded by the proposed LOV relays and existing DV relays meet the current licensing basis without the proposed new MSP relays.

Therefore, the NRC staff requests the licensee to confirm whether the MSPs provide part of the protection needed to meet the current licensing basis for the ANO grid undervoltage protection scheme described in Section 8.3.1.5 of the ANO SAR.

RAI EEOB-2 The NRC staff needs additional information to verify the licensees conclusion in the LAR that, instantaneous voltage drop below the DV relay setpoint which remains above the LOV relay setpoint is not considered credible. Therefore, the NRC staff requests the licensee to provide details of (or excerpts from) the technical justification contained in the system analysis (as defined by Section 8.3.1.5.1, Position 1: Response 1, Item C.3, of the ANO-1 SAR) for ANO-1 that forms the basis of the above conclusion.

RAI EEOB-3 In its LAR, the licensee stated, The most recent offsite power grid study (completed in 2017) supports the assumption that sustained voltage degradation below the DV setpoint is not credible for the ANO-1 unit. The NRC staff requests the licensee to clarify if the offsite power grid study accounts for equipment malfunctions or failures, electrical faults, or human performance issues similar to those discussed in Licensee Event Reports and/or identified by the ANO corrective action program.

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