ML21040A513

Issuance of Amendment No. 271 Revision to Loss of Voltage Relay Allowable Values

ML21040A513
Person / Time
Site:	Arkansas Nuclear
Issue date:	03/10/2021
From:	Jennifer Dixon-Herrity Plant Licensing Branch IV
To:	Entergy Operations
Wengert T - NRR/DORL 301-415-4037
References
EPID L-2020-LLA-0013
Download: ML21040A513 (25)

Text

March 10, 2021 ANO Site Vice President Arkansas Nuclear One Entergy Operations, Inc.

N-TSB-58 1448 S.R. 333 Russellville, AR 72802

SUBJECT:

ARKANSAS NUCLEAR ONE, UNIT 1 - ISSUANCE OF AMENDMENT NO. 271 RE: REVISION TO LOSS OF VOLTAGE RELAY ALLOWABLE VALUES (EPID L-2020-LLA-0013)

Dear Sir or Madam:

The U.S. Nuclear Regulatory Commission (NRC, the Commission) has issued the enclosed Amendment No. 271 to Renewed Facility Operating License No. DPR-51 for Arkansas Nuclear One, Unit 1 (ANO-1). The amendment consists of changes to the Technical Specifications (TSs) in response to your application dated January 24, 2020, as supplemented by letters dated March 19, 2020, and October 5, 2020.

The amendment revises the current loss-of-voltage relay allowable values contained in ANO-1 TS 3.3.8, Diesel Generator (DG) Loss of Power Start (LOPS), to address, in part, information contained in NRC Regulatory Issue Summary 2011-12, Adequacy of Station Electric Distribution System Voltages, Revision 1, dated December 29, 2011.

A copy of the related Safety Evaluation is also enclosed. Notice of Issuance will be included in the Commissions monthly Federal Register notice.

Sincerely,

/RA/

Thomas J. Wengert, Senior Project Manager Plant Licensing Branch IV Division of Operating Reactor Licensing Office of Nuclear Reactor Regulation Docket No. 50-313

Enclosures:

1. Amendment No. 271 to DPR-51

2. Safety Evaluation cc: Listserv

ENTERGY OPERATIONS, INC.

DOCKET NO. 50-313 ARKANSAS NUCLEAR ONE, UNIT 1 AMENDMENT TO RENEWED FACILITY OPERATING LICENSE Amendment No. 271 Renewed License No. DPR-51

1.

The U.S. Nuclear Regulatory Commission (the Commission) has found that:

A.

The application for amendment by Entergy Operations, Inc. (the licensee), dated January 24, 2020, as supplemented by letters dated March 19, 2020, and October 5, 2020, complies with the standards and requirements of the Atomic Energy Act of 1954, as amended (the Act), and the Commissions rules and regulations set forth in 10 CFR Chapter I; B.

The facility will operate in conformity with the application, the provisions of the Act, and the rules and regulations of the Commission; C.

There is reasonable assurance (i) that the activities authorized by this amendment can be conducted without endangering the health and safety of the public, and (ii) that such activities will be conducted in compliance with the Commissions regulations; D.

The issuance of this amendment will not be inimical to the common defense and security or to the health and safety of the public; and E.

The issuance of this amendment is in accordance with 10 CFR Part 51 of the Commissions regulations and all applicable requirements have been satisfied.

2.

Accordingly, the license is amended by changes to the Technical Specifications as indicated in the attachment to this license amendment, and paragraph 2.c.(2) of Renewed Facility Operating License No. DPR-51 is hereby amended to read as follows:

(2)

Technical Specifications The Technical Specifications contained in Appendix A, as revised through Amendment No. 271, are hereby incorporated in the renewed license. EOI shall operate the facility in accordance with the Technical Specifications.

3.

This amendment is effective as of its date of issuance and shall be implemented prior to startup from Refueling Outage 1R29 (spring 2021) coincident with the necessary plant modifications to be performed in 1R29 to address Regulatory Issue Summary 2011-12.

FOR THE NUCLEAR REGULATORY COMMISSION Jennifer L. Dixon-Herrity, Chief Plant Licensing Branch IV Division of Operating Reactor Licensing Office of Nuclear Reactor Regulation

Attachment:

Changes to Renewed Facility Operating License No. DPR-51 And the Technical Specifications Date of Issuance: March 10, 2021 Jennifer L.

Dixon-Herrity Digitally signed by Jennifer L. Dixon-Herrity Date: 2021.03.10 13:46:14 -05'00'

ATTACHMENT TO LICENSE AMENDMENT NO. 271 RENEWED FACILITY OPERATING LICENSE NO. DPR-51 ARKANSAS NUCLEAR ONE, UNIT 1 DOCKET NO. 50-313 Replace the following pages of Renewed Facility Operating License No. DPR-51 and the Appendix A, Technical Specifications, with the attached revised pages. The revised pages are identified by amendment number and contain marginal lines indicating the areas of change.

Renewed Facility Operating License REMOVE INSERT 3

3 Technical Specifications REMOVE INSERT 3.3.8-2 3.3.8-2

(5)

EOI, pursuant to the Act and 10 CFR Parts 30, 40 and 70, to receive, possess and use in amounts as required any byproduct, source or special nuclear material without restriction to chemical or physical form, for sample analysis byproduct, source or special nuclear material without restriction to chemical or physical form, for sample analysis or instrument calibration or associated with radioactive apparatus or components; (6)

EOI, pursuant to the Act and 10 CFR Parts 30 and 70, to possess, but not separate, such byproduct and special nuclear materials as may be produced by the operation of the facility.

c.

This renewed license shall be deemed to contain and is subject to the conditions specified in the following Commission regulations in 10 CFR Chapter I: Part 20, Section 30.34 of Part 30, Section 40.41 of Part 40, Sections 50.54 and 50.59 of Part 50, and Section 70.32 of Part 70; is subject to all applicable provisions of the Act and to the rules, regulations, and orders of the Commission now or hereafter in effect; and is subject to the additional conditions specified or incorporated below:

(1)

Maximum Power Level EOI is authorized to operate the facility at steady state reactor core power levels not in excess of 2568 megawatts thermal.

(2)

Technical Specifications The Technical Specifications contained in Appendix A, as revised through Amendment No. 271, are hereby incorporated in the renewed license.

EOI shall operate the facility in accordance with the Technical Specifications.

(3)

Safety Analysis Report The licensees SAR supplement submitted pursuant to 10 CFR 54.21(d),

as revised on March 14, 2001, describes certain future inspection activities to be completed before the period of extended operation. The licensee shall complete these activities no later than May 20, 2014.

(4)

Physical Protection EOI shall fully implement and maintain in effect all provisions of the Commission-approved physical security, training and qualification, and safeguards contingency plans, including amendments made pursuant to provisions of the Miscellaneous Amendments and Search Requirements revisions to 10 CFR 73.55 (51 FR 27817 and 27822) and to the authority of 10 CFR 50.90 and 10 CFR 50.54(p). The combined set of plans, which contains Safeguards Information protected under 10 CFR 73.21, is entitled: Arkansas Nuclear One Physical Security Plan, Training and Qualifications Plan, and Safeguards Contingency Plan, as submitted on May 4, 2006.

Renewed License No. DPR-51 Amendment No. 271 Revised by letter dated July 18, 2007

DG LOPS 3.3.8 ANO-1 3.3.8-2 Amendment No. 215,264, SURVEILLANCE FREQUENCY SR 3.3.8.2

---

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

When DG LOPS instrumentation is placed in an inoperable status solely for performance of this Surveillance, entry into associated Conditions and Required Actions may be delayed up to 4 hours4.62963e-5 days <br />0.00111 hours <br />6.613757e-6 weeks <br />1.522e-6 months <br /> for the loss of voltage Function, provided the one remaining relay monitoring the Function for the bus is OPERABLE.

Perform CHANNEL CALIBRATION with setpoint Allowable Value as follows:

a.

Degraded voltage 423.2 V and 436.0 V with a time delay of 8 seconds +/- 1 second; and b.

Loss of voltage 3251.5 V and 3349.5 V with a time delay of 2.0 seconds and 2.6 seconds.

In accordance with the Surveillance Frequency Control Program 271

SAFETY EVALUATION BY THE OFFICE OF NUCLEAR REACTOR REGULATION RELATED TO AMENDMENT NO. 271 TO RENEWED FACILITY OPERATING LICENSE NO. DPR-51 ENTERGY OPERATIONS, INC.

ARKANSAS NUCLEAR ONE, UNIT 1 DOCKET NO. 50-313

1.0 INTRODUCTION

By application dated January 24, 2020 (Agencywide Documents Access and Management System (ADAMS) Accession No. ML20024E639), as supplemented by letters dated March 19, 2020, and October 5, 2020 (ADAMS Accession Nos. ML20079K973 and ML20279A827, respectively), Entergy Operations, Inc. (Entergy, the licensee), requested changes to the Technical Specifications (TSs) for Arkansas Nuclear One, Unit 1 (ANO-1).

The proposed changes would revise the current loss-of-voltage (LOV) relay allowable values (AVs) contained in TS 3.3.8, Diesel Generator (DG) Loss of Power Start (LOPS). The license amendment request (LAR) was submitted, in part, to address information contained in U.S. Nuclear Regulatory Commission (NRC, the Commission) Regulatory Issue Summary (RIS) 2011-12, Adequacy of Station Electric Distribution System Voltages, Revision 1, dated December 29, 2011 (ADAMS Accession No. ML113050583).

The supplemental letter dated October 5, 2020, provided additional information that clarified the application, did not expand the scope of the application as originally noticed, and did not change the NRC staffs original proposed no significant hazards consideration determination as published in the Federal Register on May 19, 2020 (85 FR 29981).

2.0 REGULATORY EVALUATION

2.1 System Description - Loss of Power Instrumentation Two levels of undervoltage protection (i.e., LOV and degraded voltage (DV)) are provided for the ANO-1 onsite power system. There are two redundant and independent 4160 volt (V) safety buses (2A3 and 2A4), and each safety bus has LOV protection. The LOV protection is provided by two inverse time undervoltage relays on each of the 4160 V safety buses that isolate the safety buses upon detection of LOV, initiate load shedding, and start the associated DG. The two 4160 V LOV relays per safety bus are connected in parallel such that single relay failure will not prevent isolation of the associated bus from its offsite power source.

The 4160 V emergency buses provide electrical power to safety-related equipment such as pump motors, motor operated valves (MOVs) and associated control components. The DG LOPS protection instrumentation detects the voltage on each 4160 V Class 1E bus. The emergency DGs provide a source of emergency power when offsite power is either unavailable or is insufficiently stable to allow operation of safety-related loads. In the LAR, the licensee stated that undervoltage protection devices generate a LOPS of the emergency DGs in the event an LOV or a DV condition occurs on select ANO-1 switchgear or load centers.

Currently, there are two undervoltage relays with inverse voltage time characteristics for each 4160 V Class 1E bus switchgear for the purpose of detecting a loss of bus voltage. The LOV relay AVs are based on a maximum setting, which is below the lowest allowed motor terminal momentary voltage of 75 percent of a motor voltage rating of 4000 V. The AVs are adjusted to include channel uncertainties and calibration tolerances within plant procedures such that actual in-plant relay settings are conservative to the AVs. Upon loss of power to either of these relays, in approximately 2.0 seconds, load shedding and starting of the associated DG are initiated.

Isolation of the safety-related buses is delayed approximately 2.50 seconds to allow an automatic transfer to offsite power. The safety-related bus is isolated only if the transfer is unsuccessful.

In addition to the above, the two proposed definite time DV undervoltage relays are provided on each safety-related 480 V load center bus with a coincident trip logic (2 out of 2) for the purpose of detecting a sustained undervoltage condition. The undervoltage DV relay (DVR) AVs on the 480 V bus are based on long-term, motor voltage requirements plus the maximum feeder voltage drop allowance resulting in a nominal setting of 92 percent of the motor rated voltage of 460 V. The AVs are adjusted to include channel uncertainties and calibration tolerances within plant procedures such that actual in-plant relay settings are conservative to the AVs. Upon voltage degradation to 92 percent of 460 V and after a delay of approximately 8 seconds, both DVRs must operate to isolate the associated safety-related 4160 V bus from offsite power, and start and connect the associated DG. The DVRs are delayed approximately 8.0 seconds to prevent spurious operation of the relays when large motors start on the safety-related 4160 V and 480 V buses. The LOPS is further described in Section 8.3.1, AC [Alternating Current]

Power Systems, of the ANO-1 Safety Analysis Report (SAR) Amendment 29 (redacted)

(ADAMS Accession No. ML20133J853).

2.2 Regulatory Requirements ANO-1 was designed and constructed to meet the intent of the Atomic Energy Commissions General Design Criteria (GDC) for Nuclear Power Plant Construction Permits, as originally proposed in July 1967. The ANO-1 construction permit was issued on December 6, 1968, prior to the 1971 publication of Appendix A, General Design Criteria for Nuclear Power Plants, to Title 10 of the Code of Federal Regulations (10 CFR) Part 50. As such, compliance with the explicit requirements of the GDC is not required, as long as the intent of the GDC is met.

Section 1.4 of the ANO-1 SAR describes the manner in which the ANO-1 GDC meet the intent of the GDC in Appendix A of 10 CFR Part 50.

ANO-1 SAR Section 1.4.9 describes the ANO designs conformance with GDC 13, Instrumentation and control, of Appendix A to 10 CFR Part 50 requirements. Detailed instrumentation and control design information is provided in Section 7 of the ANO-1 SAR.

GDC 13, Instrumentation and control, of Appendix A to 10 CFR Part 50, states, that:

Instrumentation shall be provided to monitor variables and systems over their anticipated ranges for normal operation, for anticipated operational occurrences, and for accident conditions as appropriate to assure adequate safety, including those variables and systems that can affect the fission process, the integrity of the reactor core, the reactor coolant pressure boundary, and the containment and its associated systems. Appropriate controls shall be provided to maintain these variables and systems within prescribed operating ranges.

ANO-1 SAR Sections 1.4.13 and 8.3.1.2 describe the ANO designs conformance with GDC 17, Electric power systems, of Appendix A to 10 CFR Part 50 requirements.

GDC 17, Electric power systems, of Appendix A to 10 CFR Part 50, states, in part, that:

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, Technical Specifications, requires, in part, that TSs shall be included by applicants for a license authorizing operation of a production or utilization facility.

The regulation in 10 CFR 50.36(c) requires that TSs 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, (3) surveillance requirements (SRs), (4) design features, and (5) administrative controls. The regulation does not specify the particular requirements to be included in a plants TSs.

The regulation in 10 CFR 50.36(c)(1)(ii)(A) states, in part, that:

Limiting safety system settings for nuclear reactors are settings for automatic protective devices related to those variables having significant safety functions.

Where a limiting safety system setting is specified for a variable on which a safety limit has been placed, the setting must be so chosen that automatic protective action will correct the abnormal situation before a safety limit is exceeded. If, during operation, it is determined that the automatic safety system does not function as required, the licensee shall take appropriate action, which may include shutting down the reactor.

The regulation in 10 CFR 50.36(c)(3), Surveillance requirements, states that SRs 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.

The regulation in 10 CFR 50.55a(h), Protection and safety systems, requires, in part, that protection systems for plants with construction permits issued after January 1, 1971, but before May 13, 1999, must meet the requirements stated in either Institute of Electrical and Electronics

Engineers (IEEE) Std. 279-1968, Proposed IEEE Criteria for Nuclear Power Plant Protection Systems, IEEE Std. 279-1971, Criteria for Protection Systems for Nuclear Power Generating Stations, or IEEE Std. 603-1991, Criteria for Safety Systems for Nuclear Power Generating Stations, and the correction sheet dated January 30, 1995. For nuclear power plants with construction permits issued before January 1, 1971, protection systems must be consistent with their licensing basis or may meet the requirements of IEEE Std 603-1991 and the correction sheet dated January 30, 1995. The ANO-1 construction permit was issued on December 6, 1968.

A brief description of conformance of the undervoltage protection and load shedding features to the requirements of IEEE Std. 279-1971 is provided in ANO-1 SAR Sections 7.3.4.1.3, Evaluation Criteria; 8.3.1.4, Independence of Redundant Systems; 8.3.1.5, Grid Undervoltage Protection (Millstone 2 and ANO Events); and 8.3.1.6, Description of Changes.

ANO-1 SAR Section 8.3.1.4 states, in part, that:

The Class 1E electric systems are designed to insure [sic] that any of the design basis events listed in IEEE 308-1971 will not prevent operation of the minimum number of ESF equipments [sic] required to safely shutdown the reactor and to maintain a safe post-shutdown condition.

The Class 1E power system is designed to meet the requirements of IEEE 279-1971, IEEE 308-1971, 10 CFR [Part] 50, including Appendices A and B, and Safety Guide 1.6.

2.3 Regulatory Guidance Regulatory Guide (RG) 1.105, Revision 3, Setpoints for Safety-Related Instrumentation, dated December 1999 (ADAMS Accession No. ML993560062), describes a method acceptable to the NRC staff for complying with the NRCs regulations for ensuring that setpoints for safety-related instrumentation are initially within and remain within the TS limits. RG 1.105 endorses PartI of Instrument Society of America1 (ISA) Standard 67.04-1994 (ISA-S67.04-1994), Setpoints for Nuclear Safety-Related Instrumentation. The NRC staff used RG 1.105, Revision 3, to establish the adequacy of the licensees setpoint calculation methodologies and the related plant surveillance procedures.

NRC RIS 2006-17, NRC Staff Position on the Requirements of 10 CFR 50.36, Technical Specifications, Regarding Limiting Safety System Settings During Periodic Testing and Calibration of Instrument Channels, dated August 24, 2006 (ADAMS Accession No. ML051810077), discusses issues that could occur during testing of limiting safety system settings and which, therefore, may have an adverse effect on equipment operability. The RIS also represents an approach that is acceptable to the NRC staff for addressing these issues in licensing actions.

RIS 2011-12, Revision 1, clarifies voltage studies necessary for DVR (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 of Appendix A to 10 CFR Part 50. RIS 2011-12, Revision 1, states, in part, that Licensee voltage calculations should provide the basis for their DVR settings, ensuring safety-related equipment 1 In 2008, the name of this organization was changed to International Society of Automation.

is supplied with adequate voltage (dependent on equipment manufacturers design requirements), based on bounding conditions for the most limiting safety-related load (in terms of voltage) in the plant.

2.4 Proposed Change The proposed amendment would modify TS 3.3.8 for ANO-1. Specifically, the proposed amendment would revise the LOV relay AVs stated in SR 3.3.8.2.b, as follows:

Existing SR 3.3.8.2.b states:

Loss of voltage [greater than or equal to] 1600 V and [less than or equal to]

3000 V with a time delay of 0.30 seconds and 0.98 seconds.

Proposed SR 3.3.8.2.b would state:

Loss of voltage 3251.5 V and 3349.5 V with a time delay of 2.0 seconds and 2.6 seconds.

In its supplemental letter dated March 19, 2020, the licensee provided a summary calculation for the new LOV relay trip setpoint and associated time delay. This summary setpoint calculation shows that the LOV setpoint is based on the current TS AV of 3000 V and that the proposed values also include anticipated voltage drop plus margin and allowances for channel uncertainty. The licensee also stated, in part, that the minimum allowable time delay of 2 seconds is sufficient to ride through transfer to an alternate offsite source without tripping, and that the maximum allowable time delay of 2.6 seconds ensures protection of safety-related equipment.

The licensee did not propose to change the existing DVR TS voltage and time delay AVs.

In the LAR, the licensee described the addition of Motor Start Protection (MSP) relays, which are additional DVRs wired in parallel with the existing DVRs. In the enclosure to the LAR, the licensee stated, in part, that The MSP 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 in the LAR, that 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.

3.0 TECHNICAL EVALUATION

3.1 Evaluation of Proposed LOV Relay Change 3.1.1 LOV Relay Voltage Settings The current LOV protection consists of two inverse-time undervoltage relays on each of the 4160 V safety buses that act to detect LOV, isolate the safety buses, initiate load shedding, and start the associated onsite power source within approximately 1 second. The existing relays

maximum setting is based on the lowest allowed motor terminal momentary voltage of 75 percent of the motor voltage rating of 4000 V.

The licensee reevaluated the undervoltage protection scheme at ANO-1 and is implementing modifications to protect important in-plant equipment from damage during undervoltage conditions. As part of the modifications, the licensee is replacing the existing inverse time LOV relays with new ABB model 27N definite time relays. The licensee has requested a change to the TS LOV relay voltage and time delay settings. The proposed actuation range of the new LOV relays is 3251.5 V to 3349.5 V with a time delay of 2.0 seconds and 2.6 seconds. The proposed actuation voltage range is based on maintaining the current protection of not going below a momentary motor voltage of 3000 V. The 2.6-second maximum relay operation time coupled with the proposed 2.5-second time delay (+/- 10 percent) following LOV relay time-out before the 480 V load center bus is de-energized (for a total of 5.35 seconds) has the potential for imposing undervoltage conditions on safety-related equipment for a longer duration. The licensee has evaluated the impact of low voltage conditions and the proposed time delay associated with separating the safety loads when the LOV relays detect undervoltage conditions.

In the enclosure to the LAR, the licensee stated, in part, that:

Given the new LOV relay allowable voltage and time delay values proposed above, the revised analysis shows that the protective relays for 4160 V motor loads will not trip if the motor is drawing locked-rotor current for a time period equal to the maximum LOV relay time delay plus the acceleration time of the motor on the onsite source (as discussed previously, the MSP or DV relays prevent loss of 480 V motors and MOVs). The LOV relay setting also ensures that 4160 V and 480 V motors will not stall if already running.

The licensee further stated in the LAR, that, This additional delay time and exposure to degraded voltage conditions does not result in the loss of any required plant equipment.

Based on the information provided by the licensee, the NRC staff finds the revised changes to the LOV relay setpoints, and the change in delay time for separating the safety buses from a degraded power source, to be reasonable because the changes will continue to permit functioning of structures, systems, and components important to safety in compliance with GDC 17.

3.1.2 Sustained Degraded Voltages and Motor Start Protection Relays The licensee stated in the LAR that no changes were being made to the existing DVR setpoints.

The licensee also provided information regarding new MSP relays that provide additional protection against sustained DV conditions. ANO-1s DVR licensing basis is documented in its SAR and TSs. The DVR function is separate from the LOV function and is outside of the scope of this LAR. Therefore, the NRC staff made no determinations regarding DVRs, MSPs, or the potential for sustained DV conditions in this safety evaluation.

3.1.3 Summary of NRC Staffs Evaluation of Proposed LOV Relay Change The LAR was evaluated by the NRC staff in accordance with the current licensing basis of ANO-1 with respect to LOV conditions. The proposed changes to the LOV relays and corresponding TS provide reasonable assurance that equipment required to mitigate the

consequences of an accident will be protected and available when offsite sources degrade to an unacceptable level. The NRC staff determined that the proposed LOV relay change at ANO-1 will maintain the licensees current compliance related to GDC 17 and 10 CFR 50.55a(h) requirements.

3.2 Evaluation of Proposed TS Settings The NRC staff reviewed the licensees regulatory and technical analyses in support of the proposed changes, as described in the LAR and supplements. The NRC staff performed an independent confirmatory evaluation to:

Verify the licensees setpoint calculation methodology, using the square root of the sum of the squares (SRSS), to assure that control and monitoring setpoints are established and maintained in a manner consistent with plant safety function requirements.

Verify that the licensees setpoint calculation values are adequate to assure, with a high confidence level, that required protective actions are initiated before the associated plant process parameters exceed their analytical limits (ALs).

The NRC staff evaluated the proposed amendment using the criteria of RG 1.105, Revision 3, and referenced ISA-S67.04-1994, Part 1, to determine if the proposed new setpoints for DV, LOV, and time delay of safety-related instrumentation are established and maintained within the TS limits. The following definitions, from ISA-S67.04-1994, were used in the NRC staff evaluation:

AL - Limit of a measure or calculated variable established by the safety analysis to ensure that a safety limit is not exceeded.

AV - A limiting value that the trip setpoint may have when tested periodically, beyond which appropriate action shall be taken.

Trip Setpoint - A predetermined value for actuation of the final setpoint device to initiate a protective action.

Additionally, Section 4.3.1 of ISA-S67.04-1994, discusses the trip setpoint and provides a general discussion from which the following definition can be established:

Margin - an allowance provided between the trip setpoint and the analytical limit to ensure a trip before the analytical limit is reached.

Finally, the NRC staff evaluated the LAR for its conformance with RIS 2006-17 regarding whether the licensee properly used the NRC staffs guidance in establishing AVs, nominal setpoints, and as-left and as-found tolerances to be used during periodic surveillances.

3.2.1 Summary of Licensee Methodology The NRC staff reviewed the summary of the calculations provided in the enclosure to the licensees supplemental letter dated March 19, 2020. The NRC staff confirmed the following with respect to the licensees methodology:

The setting tolerance to establish an acceptable as-found setpoint range was calculated using the SRSS; The relay drift is calculated based on the performance of a statistical analysis of the as-left and as-found data (32 data points over a 6-year period). The total loop error was calculated using the SRSS plus algebraic approaches.

The methods used by the licensee for combining uncertainties for the proposed SR 3.3.8.2.b values are consistent with the guidance in Section 4.4 Combination of uncertainties, from ISA-S67.04-1994, and Regulatory Position C.1 from RG 1.105, Revision 3. Additionally, a figure on page 6 of the enclosure to the supplemental letter dated March 19, 2020, shows the relationship between the AV for relay drift and margin, channel uncertainty, and the desired setting. This figure and the relationships shown align with those shown in Figure 1, Nuclear Safety-Related Setpoint Relationships, in RG 1.105, Revision 3. The NRC staff found that the SRSS methodology used to calculate the proposed AV (as shown in the summary of the licensees calculations for the LOV setting values in Section 3.2.2 of this safety evaluation), is consistent with the methodology in the ISA-S67.04-1994 and the guidance in RG 1.105, Revision 3, and therefore, would assure that control and monitoring setpoints are established and maintained in a manner consistent with plant safety function requirements.

3.2.2 Evaluation of Setpoint AVs of LOV Relay Settings of SR 3.3.8.2.b 3.2.2.1 Evaluation of the AV for the LOV Relay Setting The licensee proposed to change the AV of the LOV relay setting in ANO-1 SR 3.3.8.2.b, as follows:

Allowable Value for LOV Relay Setting Existing Proposed 1600 V and 3000V 3251.5 V and 3349.5V In its supplemental letter dated March 19, 2020, the licensee provided specific results from the calculations for the proposed new AVs for the LOV setting values. The licensee stated, in part:

The safety related 4160 V switchgears A3 and A4 LOV relays are the same model of 27N relays used on the safety related 480 V load centers B5 and B6.

Therefore, the relay uncertainty and drift values calculated in CALC-95-E-0001-01 for the B5 and B6 relays are used to determine the A3 and A4 LOV relay dropout and pickup settings.

The relay drift is calculated based on the performance of a statistical analysis of the as-left and as-found data (32 data points over a 6-year period). Based on this statistical analysis, the relay dropout voltage drift is documented as 0.816%.

The NRC staff reviewed the summary of the ANO-1 LOV relay setpoint uncertainty calculation that supported the proposed AV in the TS SRs. The summary included the relay setting design basis, such as the nominal trip setpoint (NTS) (or desired relay dropout voltage (VDRD)) to be used during calibration surveillances, the uncertainties associated with these settings, the expected relay drift between surveillances, the uncertainties associated with these settings (inclusive of the (potential transformer ratio (PTR)), the expected relay drift between surveillances, measurement and test equipment uncertainties, and the as-found and as-left tolerance acceptance values to be applied during TS surveillances.

The licensee also provided the full ABB Single Phase Voltage Relays Type 27N catalog number (Model 411T5175-HF-L). The NRC staff reviewed the vendor instruction manual of this model to verify that the applicable pickup and dropout voltage adjustment allows for the difference between pickup and dropout to be set as low as 0.5 percent, and that the performance tolerances (the temperature effect in the repeatability over temperature range is 0.4 percent without harmonic filter) in the ANO-1 LOV relay setpoint uncertainty calculation are consistent with the data in this vendor instruction manual.

In the ANO-1 LOV relay setpoint uncertainty calculation, the licensee used the following variables:

Table 1: Variables Used in the Licensees Calculation:

% of VDRD (or NTS) Setting Process Measurement PM 0.3%

Module Reference Accuracy RA 0.2%

Voltage Effect VE 0.1%

Temperature Effect TE 0.4% (over temperature range -20 to +55 degrees Celsius)

Measurement and Test Equipment (M&TE) Effect MTE 0.2%

Relay Drift RD 0.816%

Potential Transformer Ratio PTR 4200/120

% of Motor Rated Voltage of 4000V Minimum Acceptable Dropout VMA 8.13%

In the calculation, the licensee initially calculated the total Channel Uncertainty (CU) or total loop uncertainties, including the 0.3 class potential transformer (PT) by the equation:

CU = +/- ((PM)2 + (((RA)2 + (TE)2 + (VE)2 + (MTE)2)1/2)2 )1/2 In the enclosure to the LAR, the licensee stated, in part, that The existing relay allowable values are based on a maximum setting, which is below the lowest allowed motor terminal momentary voltage of 75% of the motor voltage rating of 4000 V.

The licensee determined the VDRD or NTS from VMA, using the equation below:

VDRD (NTS) = [(VMA)(4000 V)(1/PTR)] / (1 - RD)(1 - CU)

The licensee used the vendor catalog information to obtain the nominal pickup voltage and 0.5 percent band (the difference between pickup and dropout voltage). Therefore, the pickup is set at VDRD/0.995.

The licensee determined the As-Left limits by adding the calibration tolerance (0.1 V: as-left tolerance (ALT)) to the dropout calibration upper/lower limit (VDRD +/- 0.1 V calibration tolerance).

The as-found tolerance (AFT) for the voltage was calculated from the measurement and test equipment (M&TE) accuracy and relay dropout voltage drift by the equation below:

AFT = (RA2 + M&TE2)1/2 + RD The NRC staff determined that this method of determining AFT is consistent with the guidance in RIS 2006-17.

The dropout maximum/minimum As-Found limits were determined by adjusting the VDRD by the AFT:

The Upper/Lower As-Found Limits = VDRD x (1 +/- AFT)

The allowable limits (upper/lower AV) were calculated and adjusted for the channel uncertainties, relay drift, and margin (the 0.1 V is added for margin), as follows:

Dropout Upper/Lower Setting Adjusted for CU = (VDRD x (1 +/- CU)) + 0.1 V The maximum TS AV was adjusted for channel uncertainties, relay drift, and margin (0.1 V is added for margin), and the minimum TS AV was adjusted for VMA. Accordingly, the AV was proposed, as follows:

Maximum TS AV = (VDRD/0.995) x (1 + RD) + 0.1 V Minimum TS AV = (VMA x (4000 V) x (PTR)

In the supplemental letter dated March 19, 2020, the licensee provided a figure, shown in Figure 1 below, as a high-level summary of the various calibration components.

Figure 1: The Licensees Summary of the Calibration of the LOV Relay The NRC staff summarized the results of the calculation from the equations above as shown in Table 2 below:

Table 2: LOV Setting Results from the Licensees Calculation CU = 0.56% of NTS VDRD = 94.2 V + 0.1V (added margin) = 94.3 V or 82.5% of Motor Rated Voltage (3300.5 V)

Nominal pickup voltage and 0.5% band = 94.8 V or 83.0% of Motor Rated Voltage (3318.0 V))

As-Left Upper Limit = 94.3 V + 0.1 V (calibration tolerance) = 94.4 V (3304.0 V)

As-Left Lower Limit = 94.3 V - 0.1 V (calibration tolerance) = 94.2 V (3297.0 V)

As-Found Tolerance = 0.010396 = 1.0396% of NTS Dropout Maximum As-Found Limit = 95.28 V (3334.8 V)

Dropout Minimum As-Found Limit = 93.32 V (3266.2 V)

Dropout Upper Setting Adjusted for CU = 94.8 V (3318.0 V)

Dropout Lower Setting Adjusted for CU = 93.8 V (3283.0 V)

Maximum TS Allowable = 95.7 V (3349.5 V)

Minimum TS Allowable = 92.9 V (3251.5 V)

Based on the results in Table 2 and Figure 1 above, the NRC staff subsequently used the guidance in RG 1.105, Revision 3, to independently confirm whether there are adequate margins for instrument channel performance uncertainty between the AL and NTS (MarginNTS) and associated AV (MarginAV) (for Function SR 3.3.8.2.b in ANO-1 TS 3.3.8) to satisfy the requirements of 10 CFR 50.36(c)(1)(ii)(A).

MarginAV (b) = I AL - AV I (absolute value)

MarginNTS (a) = I AL - NTS I (absolute value)

Margin Ratio % = (b/a) x 100%

The NRC staff performed a confirmatory evaluation of the MarginNTS and MarginAV of the lower level because the proposed LOV relays detect the loss of the 4160 V Class 1E bus in the event an LOV condition occurs. In this confirmatory evaluation, the NRC staff considered the minimum acceptable equipment voltage (3000 V) as the AL of the lower level. The NRC staffs evaluation and confirmatory results are summarized in Figure 2 below:

Figure 2: NRC Staff Calculation of LOV Relay AVs & NTS Relationships and Margins AL (Min)

NTS AV (Min)

ANO-1 LOV Relay Allowable Values (AVs) & Nominal Trip Setpoints (NTS)

Relationships AV (Max)

AL (Max)

NTS + AFT NTS - AFT NTS + ALT NTS - ALT

+ AFT

- AFT

+ALT

- ALT Note: Diagram Not To Scale

• VDRD: Desired Relay Dropout Voltage AL (Lower Level)

AL (Upper Level) b a

MarginAV & MarginNTS Calculation Based on the information summarized in Tables 1 and 2 and Figures 1 and 2 above, the NRC staff determined the following with respect to the proposed AVs for the ANO-1 LOV relay for SR 3.3.8.2.b:

The NTS inclusive of its AFTs are less than the maximum AV and greater than the minimum AV, ensuring that the trip signals will be initiated before NTS reach the AVs.

The margin ratio percentages between the NTS and AV margins are greater than 83 percent and are adequate. These margins ensure that the trip setpoints have been chosen to assure that a trip or safety actuation will occur significantly before the measured process reaches the lower ALs (minimum equipment acceptable voltage).

The proposed AV setting supports an automatic protective action that will correct the abnormal situation before a safety limit is exceeded.

The proposed maximum and minimum TS AVs of the LOV relay are higher than the lowest allowed motor terminal momentary voltage of 75 percent of the motor voltage rating of 4000 V to ensure that 4160 V and 480 V motors will not stall if already running to maintain these variables and systems within prescribed operating ranges.

Based on the above discussion, the NRC staff finds that the proposed LOV settings (maximum and minimum AVs) for SR 3.3.8.2.b (SR for the Channel Calibration performance) are

consistent with RG 1.105, Revision 3, and satisfy the requirements of 10 CFR 50.36(c)(1)(ii)(A) and GDC 13. Therefore, the proposed AVs ( 3349.5 V and 3251.5 V) are acceptable.

3.2.2.2 Evaluation of the AV for the LOV Time Delay Relay Setting The licensee proposed to change the LOV time delay setting for SR 3.3.8.2.b, as follows:

In the enclosure to the LAR, the licensee stated, in part, that:

Determination that the protective devices, including control equipment, for the Class 1E loads do not trip and lock-out for a duration equal to the maximum analytical limit of the time delay of the LOV relays, DV relays, or MSP relays plus the additional time needed to accelerate a given motor on the onsite power supply if a degraded voltage occurs at the initiation of a motor start that prevents the motor from starting. This was analyzed for accident conditions (i.e. with an Engineered Safeguards (ES) signal present).

In the supplemental letter dated March 19, 2020, the licensee provided specific results from the calculations for the proposed AV for the LOV time delay setting values in the table above.

In the enclosure to the supplemental letter dated March 19, 2020, the licensee stated, in part:

Since the new time delay is longer than the existing time delay, the requirements above are maintained with the new time delay. Adjustments for Calibration Tolerance, Channel Uncertainty, and Relay Drift are accounted for in the time delay settings. The relay dropout setting is confirmed to be able to ride through system transients since the voltage recovers to above the pickup setting within the TS Allowable lower limit of 2.0 seconds.

Because the A3 and A4 switchgear LOV relays are the same model of 27N relays used on the B5 and B6 load centers, the relay timer uncertainty and drift values calculated in CALC-95-E- 0001-01 for the B5 and B6 relays were used to validate the A3 and A4 LOV relay time delay setting of 2.3 seconds. A time delay of 2.3 seconds is established based on motor stall times for the affected buses, given the maximum voltage drop experienced by these buses when starting large motors. CALC-18-E-0015-01 verifies the acceptability of this setpoint selection. [Emphasis added]

The relay timer drift is calculated based on the performance of a statistical analysis of the as-left and as-found data (32 data points over a 6-year period).

The relay timer drift is documented as 0.45% [of time delay setting].

Similar to the LOV relay setting, the summary of the LOV time delay calculation included the relay setting design basis, such as the designed time delay relay to be used during calibration surveillances, the uncertainties associated with these settings, the expected relay drift between AV for LOV Time Delay Relay Setting Existing Proposed 0.30 seconds and 0.98 seconds 2.00 seconds and 2.60 seconds

surveillances, M&TE uncertainties, and the AFT and ALT tolerance acceptance values to be applied during TS surveillances.

The licensee also provided the full ABB Single Phase Voltage Relays Type 27N catalog number (Model 411T5175-HF-L). The NRC staff reviewed the vendor instruction manual of this model to verify that the performance tolerances in the ANO-1 LOV time delay relay setpoint uncertainty calculation (i.e., the temperature effect (TE) in the repeatability over temperature range uncertainty is 1 percent (greater than 0.4 percent without harmonic filter and greater than 0.75 percent with harmonic filter) and the Module Reference Accuracy (RA) is 10 percent) are consistent with the data in this vendor instruction manual.

The NRC staff reviewed the licensees summary of the ANO-1 LOV time delay relay setpoint uncertainty calculation that supported the proposed AV in the TS SRs.

In the ANO-1 LOV time delay relay setpoint uncertainty calculation, the licensee used the following variables:

Table 3: Variables Used in the Licensees LOV Time Delay Settings Calculation Variable Acronym

% of Time Delay Settings Time Delay Setting TD 2.3 seconds Process Measurement Uncertainty PM 0%

Module Reference Accuracy RA 10%

Voltage Effect VE 0%

Temperature Effect*

TE 1%

Measurement and Test Equipment (M&TE) Effect MTE 2%

Relay Drift RD 0.45%

• TE: When the effect of voltage variation and temperature variation on the relays is not available from the manufacturer, the total effect is assumed to be 1 percent of TD.

The NRC staff created a brief summary of the calculation. The licensee first calculated the total CU or total loop uncertainties, by the equation below:

CU = +/- ((PM)2 + (((RA)2 + (TE)2 + (VE)2 + (MTE)2)1/2)2 )1/2 The time delay upper band (TUB) and time delay lower band (TLB) were determined as follows:

TUB = (TD)(1 + CU)(1 + RD)

TLB = (TD)(1 - CU)(1 - RD)

The licensee determined the As-Left limits by adding the calibration tolerance (0.1 seconds of ALT) to the TD (TD +/- 0.1 seconds calibration tolerance).

The AFT for the voltage was calculated from the M&TE accuracy and relay dropout voltage drift by the equation below:

AFT = (RA2 + M&TE2)1/2 + RD

The maximum/minimum As-Found limits were determined by adjusting the TD by the AFT:

The Maximum/Minimum As-Found Limits = TD x (1 +/- AFT)

The NRC staff summarized the results of the calculations above, as shown in Table 4 below:

Table 4: Results of Licensees Calculation of LOV Time Delay Settings Channel Uncertainty (CU) = 10.2 percent of time delay setting (TD)

TUB = 2.55 seconds (s) (using 2.6 s for margin)

TLB = 2.06 s (using 2.0 s for margin)

As-Left (Calibration) Upper Limit = 2.4 s As-Left (Calibration) Lower Limit = 2.2 s AFT = 0.10648 = 10.648 percent of TD Maximum As-Found Limit = 2.54 s Minimum As-Found Limit = 2.06 s In the supplemental letter dated March 19, 2020, the licensee stated, in part, that, Per the ABB vendor manual for Type 27N undervoltage relays, the Model 411T5xxx has a TD range of 2 to 20 seconds.

According to the results in Tables 3 and 4 above, the NRC staff subsequently used the guidance in RG 1.105, Revision 3, to independently confirm whether there are adequate margins for instrument channel performance uncertainty between the AL and TD (NTP) and associated AV (for Function SR 3.3.8.2.b in ANO-1 TS 3.3.8) to satisfy the requirements of 10 CFR 50.36(c)(1)(ii)(A).

The NRC staff performed an independent confirmation of the following margins between the AL and the TD (MarginTD), and between the AL and the AV (MarginAV):

MarginAV (b) = AL - AV MarginTD (a) = AL - TD (TD is the licensees term used for NTS)

Margin Ratio % = (b/a) x 100 %

The NRC staff performed a confirmatory evaluation of the MarginTD and MarginAV of the upper level time delay because the proposed maximum LOV time delay relays detect the loss of the 4.16 kilovolt Class 1E bus in the event a LOV condition occurs. On page 7 of the enclosure to the LAR, the licensee stated, in part, The protective device evaluation for 480 V motor control center (MCC) motors other than motor operated valves (MOVs) assumed the maximum 2.6-second LOV relay time delay plus a 2.5-second time delay (+/-10%) following LOV relay time-out before the 480 V load center bus is de-energized (for a total of 5.35 seconds) with the addition of acceleration time of the motor on the onsite source.

Therefore, in this confirmatory evaluation, the NRC staff considered the AL of the upper level of the LOV TDs to be 5.35 seconds.

The NRC staffs evaluation is summarized in Figure 3 below.

Figure 3: LOV Time Delay AV and TD Relationships and Margins Calculation AL (Min)

TD AV (Min)

ANO-1 LOV Time Delays Relay Settings Relationships AV (Max)

AL (Max)

TD + AFT TD - AFT TD + ALT TD - ALT

+ AFT

- AFT

+ ALT

- ALT Note: Diagram Not To Scale AL (Lower Limit)

AL (Upper Limit) b a

MarginAV & MarginTD Calculation Based on the information summarized in Tables 3 and 4 and Figure 3 above, the NRC staff determined the following with respect to the proposed AV for the LOV time delay relay for ANO-1 SR 3.3.8.2.b:

The TDs inclusive of their AFTs, are less than the maximum AV and greater than the minimum AV, ensuring that the trip signals will be initiated before TDs reach the AVs.

The margin ratio percentages between the TD and AV margins are greater than 90 percent and are adequate. These margins ensure that the trip setpoints have been chosen to assure that a trip or safety actuation will occur significantly before the measured process reaches the upper ALs. The proposed AV setting supports an automatic protective action that will correct the abnormal situation before a safety limit is exceeded The proposed maximum/minimum TS AV is within the TD range of 2 to 20 seconds of the ABB vendor manual for Type 27N undervoltage relays, Model 411T5xxx, and will maintain the associated variables and systems within prescribed operating ranges.

Based on the above, the NRC staff finds that the proposed AVs for the LOV time delay settings (maximum and minimum AV Time Delay) for ANO-1 TS SR 3.3.8.2.b (i.e., for the Channel Calibration performance) are consistent with RG 1.105, and satisfy the requirements of 10 CFR 50.36(c)(1)(ii)(A) and GDC 13. Therefore, the proposed AVs for the time delay relay settings ( 2.6 seconds and 2.0 seconds) are acceptable.

3.2.2.3 Summary of NRC Staffs Evaluation of Proposed TS Setting and Methodology As described in Section 3.2.1 of this SE, the licensees methodology used the SRSS combinatorial method to calculate the proposed settings to assure that control and monitoring setpoints are established and maintained in a manner consistent with plant safety function requirements, consistent with RG 1.105, Revision 3. Furthermore, as described in Section 3.2.2 of this SE, the NRC staff performed independent confirmatory evaluations of calculated margins and margin comparisons to confirm that required protective actions will be initiated before the associated plant process parameters exceed their ALs. Additionally, the licensees proposed as-left and as-found values associated with the setpoint changes were determined in a manner consistent with RIS 2006-17 in establishing the as-left and as-found tolerances.

Therefore, the NRC staff finds that the proposed changes in TS SR 3.3.8.2.b are acceptable, because the proposed changes are consistent with RG 1.105, Revision 3, which describes a method acceptable to the NRC in complying with 10 CFR 50.36(c)(1)(ii)(A) and 10 CFR Part 50, Appendix A, GDC 13. Additionally, the changes do not add or remove the surveillances, and only provide new setpoint values. The proposed changes continue to assure that the necessary quality of systems and components are maintained, and therefore, continue to meet the requirements of 10 CFR 50.36(c)(3).

4.0 STATE CONSULTATION

In accordance with the Commissions regulations, the Arkansas State official was notified of the proposed issuance of the amendment on February 18, 2021. The State official had no comments.

5.0 ENVIRONMENTAL CONSIDERATION

The amendment changes requirements with respect to installation or use of facility components located within the restricted area as defined in 10 CFR Part 20 and changes SRs. The NRC staff has determined that the amendment involves no significant increase in the amounts, and no significant change in the types, of any effluents that may be released offsite, and that there is no significant increase in individual or cumulative occupational radiation exposure. The Commission has previously issued a proposed finding that the amendment involves no significant hazards consideration published in the Federal Register on May 19, 2020 (85 FR 29984), and there has been no public comment on such finding. Accordingly, the amendment meets the eligibility criteria for categorical exclusion set forth in 10 CFR 51.22(c)(9). Pursuant to 10 CFR 51.22(b), no environmental impact statement or environmental assessment need be prepared in connection with the issuance of the amendment.

6.0 CONCLUSION

The Commission has concluded, based on the considerations discussed above, that: (1) there is reasonable assurance that the health and safety of the public will not be endangered by operation in the proposed manner, (2) there is reasonable assurance that such activities will be conducted in compliance with the Commissions regulations, and (3) the issuance of the amendment will not be inimical to the common defense and security or to the health and safety of the public.

Principal Contributors: S. Wyman H. Vu Date: March 10, 2021

ML21040A513 OFFICE NRR/DORL/LPL4/PM NRR/DORL/LPL4/LA NRR/DSS/STSB/BC NRR/DEX/EICB/BC NAME TWengert PBlechman VCusumano MWaters DATE 2/18/2021 2/17/2021 2/19/2021 9/9/2020 OFFICE NRR/DEX/EEEB/BC OGC NLO NRR/DORL/LPL4/BC NRR/DORL/LPL4/PM NAME BTitus STurk JDixon-Herrity TWengert DATE 1/29/2021 3/3/2021 03 /10 /2021 03/10/2021