Text

License Amendment Request for Technical Specification 3.3.8.1 Regarding Degraded Voltage Protection
	ML18071A363
Person / Time
Site:	Hatch
Issue date:	03/09/2018
From:	Hutto J; Southern Nuclear Operating Co
To:	; Document Control Desk, Office of Nuclear Reactor Regulation
References
	NL-18-0074
	Download: ML18071A363 (66)
	v • d • e

/

Southern Nuclear J. J. Hutto Regulatory Affairs Director 40 Inverness Center Parkway Post Office Box 1295 Birmingham, AL 35242 205 992 5872 tel 205 992 7601 lax March 9, 2018 jjhutto@southernco.com Docket Nos.: 50-321 NL-18-0074 50-366 U.S. Nuclear Regulatory Commission ATIN: Document Control Desk Washington, D. C. 20555-0001 Edwin I. Hatch Nuclear Plant Units 1 and 2 License Amendment Request for Technical Specification 3.3.8.1 Regarding Degraded Voltage Protection Ladies and Gentlemen:

Pursuant to the provisions of Section 50.90 of Title 10 of the Code of Federal Regulations (1 0 CFR), Southern Nuclear Operating Company (SNC) hereby requests an amendment to the Technical Specifications (TS) for Edwin I. Hatch Nuclear Plant (HNP) Unit 1 Renewed Facility Operating License DPR-57 and Unit 2 Renewed Facility Operating License NPF-5 and includes the results of the no significant hazards determination. The proposed amendment would revise Unit 1 and Unit 2 TS 3.3.8.1, "Loss of Power (LOP) Instrumentation" to modify the instrument allowable values for the Unit 2 4.16 kV emergency bus degraded voltage instrumentation and delete the annunciation requirements for the Unit 2 4.16 kV emergency bus undervoltage instrumentation. In addition, this amendment revises Unit 2 License Condition 2.C(3)(i) to more accurately reflect its intent.

Revision of the requirements in TS 3.3.8.1 for LOP instrumentation functions is needed to be consistent with an electrical power system modification required to satisfy Unit 1 License Condition 2.C(11) and Unit 2 License Condition 2.C(3)(i). These license conditions require SNC to implement modifications that will eliminate use of manual actions as part of the HNP degraded voltage protection scheme, and specify the schedule by which the modifications must be implemented. The proposed license amendment is an interim license change to support implementation of the Unit 2 portion of the electrical power system modification. An additional license amendment request will be submitted at a later date to support the final license change needed to support full implementation of the electrical power system modification.

SNC requests approval of the proposed license amendment by December 31, 2018 to support the implementation schedule of the electrical power system modification as specified in the respective license conditions.

Enclosure 1 provides a description of the proposed change, the supporting technical and regulatory analysis, and the no significant hazards determination. Attachment 1 provides the marked-up TS pages and the marked-up Unit 2 facility operating license page. Attachment 2 provides the clean-typed TS pages. Attachment 3 contain the marked-up TS Bases pages showing the accompanying proposed changes for information only. Attachment 4 provides a

U.S. Nuclear Regulatory Commission NL-18-0074 Page2 summary of the HNP loss of power instrumentation setpoint methodology that supports the proposed instrumentation Allowable Value changes.

This letter contains no NRC commitments.

In accordance with 10 CFR 50.91, SNC is notifying the State of Georgia of this license amendment request by transmitting a copy of this letter and enclosures to the designated State Official.

If you have any questions, please contact Ken McElroy at {205) 992-7369.

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

_!L day of March 2018.

Respectfully submitted, SOUTHERN NUCLEAR OPERATING COMPANY

~2 J. J. Hutto Director, Regulatory Affairs Southern Nuclear Operating Company JJH/RMJ

Enclosure:

1. Basis for Proposed Changes Attachments: 1. HNP Unit 2 Facility Operating License and Unit 1 and Unit 2 Technical Specifications Marked-Up Pages

2. HNP Unit 1 and Unit 2 Technical Specifications Clean-Typed Pages

3. HNP Unit 1 and Unit 2 Technical Specifications Bases Marked-Up Pages (Information Only)

4. Summary of the HNP Loss of Power Instrumentation Setpoint Methodology cc: Regional Administrator, Region II NRR Project Manager- Hatch Senior Resident Inspector- Hatch Director, Environmental Protection Division- State of Georgia RType: CHA02.004

Edwin I. Hatch Nuclear Plant, Units 1 and 2 License Amendment Request for Technical Specification 3.3.8.1 Regarding Degraded Voltage Protection Enclosure 1 Basis for Proposed Changes

Enclosure 1 to NL-18-0074 Basis for Proposed Change 1.0 Summary Description This proposed amendment to the Edwin I. Hatch Nuclear Plant (HNP) Units 1 and 2 operating licenses would revise Unit 1 and Unit 2 Technical Specification (TS) 3.3.8.1, "Loss of Power (LOP) Instrumentation" to modify the instrument allowable values (AVs) for the Unit 2 4.16 kV emergency bus degraded voltage instrumentation and delete the annunciation requirements for the Unit 2 4.16 kV emergency bus undervoltage instrumentation. The AVs associated with Unit 1 4.16 kV emergency bus LOP instrumentation are not modified and the Unit 1 annunciator requirements are not deleted as a result of the proposed amendment. This amendment is needed to reflect an electrical power system modification required to satisfy Unit 1 License Condition 2.C{11) and Unit 2 License Condition 2.C(3)(i). In addition, the proposed amendment revises the Unit 2 license condition to more accurately reflect its intent.

2.0 Detailed Description 2.1 System Design and Operation Offsite power is the preferred source of power for the 4.16 kV emergency buses which power the required components. The LOP protection instrumentation monitors voltage on the safety related 4.16 kV buses of each HNP unit. Each 4.16 kV emergency bus has independent LOP instrumentation and relay actuation logic for detecting degraded grid or loss of voltage conditions and initiating an LOP diesel generator (DG) start signal. As described, in part, in HNP Unit 1 Final Safety Analysis Report (FSAR), Section 8.4.3 and Unit 2 FSAR, Section 8.3.1.1.3, automatic starting of the DGs is initiated by undervoltage on 4.16 kV emergency

buses 1E, 1F, 1G, 2E, 2F, and 2G as a result of a complete loss-of-offsite power, a sustained degraded voltage condition, or a failure in any of the redundant instrument train's sensing voltage.

The current degraded voltage instrumentation protection scheme causes an automatic transfer from the primary source to the alternate or emergency source and disconnects certain electrical loads following a time delay. Figure 1, "Current Degraded Voltage Protection Scheme," shows the degraded voltage instrumentation logic for the 2E 4.16 kV emergency bus and associated DG 2A. The current degraded voltage instrumentation logic for each Unit 1 and Unit 2 4.16 kV emergency bus is consistent with that shown in Figure 1. As shown in Figure 1, bus degraded voltage for each 4.16 kV emergency bus is monitored by two induction disk type undervoltage relays with inverse time delay and a logic output arranged in a two-out-of-two logic configuration for supported components except the DGs. The DG start logic is arranged in a one-out-of-two configuration.

E1-1 to NL-18-0074 Basis for Proposed Change Trip System: 2E 4.16KV Bus Channels

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Figure 1 -Current Degraded Voltage Protection Scheme The current low voltage instrumentation protection scheme is similar to the degraded voltage instrumentation scheme with separate loss of voltage relays with different voltage and time delay characteristics. The loss of voltage instrumentation protection scheme and associated setpoints are not altered as a result of the electrical power system modification. Each emergency bus also has a dedicated low voltage annunciator with signal provided from two relays and associated time delays. Figure 2, "Unit 1 4.16 kV Bus Low Voltage Alarm Scheme,"

shows the annunciation instrumentation logic for the Unit 1 4.16 kV emergency buses. The logic for the Unit 1 annunciation functions is arranged in a two-out-of-two configuration as shown in Figure 2. The logic for the Unit 2 annunciation instrumentation functions is arranged in a one-out-of-two configuration.

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Figure 2 - Unit 1 4.16 kV Bus Low Voltage Alarm Scheme The current degraded voltage relays (DVRs) are intended to protect plant equipment from a sustained degraded voltage condition when the 4.16 kV emergency buses are powered from the offsite grid. The existing margins available between the minimum expected bus voltage and the voltage level required by the safety-related equipment, coupled with the inverse time operating characteristics of the existing DVRs, do not allow for resolution of the issue addressed in NRC Regulatory Issue Summary (RIS) 2011-12, "Adequacy Of Station Electric Distribution System Voltages," (Reference 1) through DVR setpoint adjustment alone. Therefore, the existing HNP degraded voltage protection scheme relies in part on manual actions to assure adequate voltage is supplied to safety-related equipment during design basis events.

In the existing protection scheme, manual action is supported by the low voltage alarm. This alarm alerts plant operators of a degraded grid voltage condition so that they can coordinate with the transmission system operators on actions to restore grid voltage. At present, these manual actions are the means relied on to protect safety-related equipment from inadequate voltages in the range where automatic protection is not provided by the DVRs.

E1-3 to NL-18-007 4 Basis for Proposed Change The modified LOP instrumentation design includes two loss of voltage relays per bus (i.e., 6 per Function per unit) and three solid state DVRs per bus (i.e., 9 per Function per unit) with each DVR relay sensing voltage from an electrically independent 4200V/120V potential transformer.

Figure 3, "Modified Degraded Voltage Protection Scheme," shows the modified degraded voltage instrumentation logic for the 2E 4.16 kV emergency bus and associated DG 2A. The modified degraded voltage instrumentation logic for each 4.16 kV emergency bus will be consistent with that shown in Figure 3 upon completion of the electrical power system modification for each unit. As shown in Figure 3, bus degraded voltage is monitored by the three DVRs with fixed time delay for each emergency bus and a logic output arranged in a two-out-of-three configuration for supported components except the DGs. The DG start logic is arranged in a one-out-of-three configuration. A two-out-of-three coincidence logic precludes spurious trips of the offsite power source due to the failure of one instrument channel, while a one-out-of-three DG start logic does not preclude a DG start in the event of a single instrument channel failure.

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Figure 3- Modified Degraded Voltage Protection Scheme 2.2 Current Operating License and Technical Specifications Requirements HNP Unit 1 License Condition 2.C(11) states: "SNC shall implement the Degraded Voltage modifications to eliminate the manual actions in lieu of automatic degraded voltage protection to assure adequate voltage to safety-related equipment during design basis events by E1-4 to NL-18-0074 Basis for Proposed Change completion of the Unit 1 2020 Spring Outage, U1 R29."

HNP Unit 2 License Condition 2.C(3)(i) states: "SNC shall implement the Degraded Voltage modifications to eliminate the manual actions in lieu of automatic degraded voltage protection to assure adequate voltage to safety-related equipment during design basis events by completion of the Unit 2 2019 Spring Outage, U2R25."

LCO 3.3.8.1 requires the instrumentation for each Function in Table 3.3.8.1-1 to be Operable in Modes 1, 2, 3, and when the associated diesel generator (DG) is required to be Operable by TS 3.8.2, "AC Sources -Shutdown." Table 3.3.8.1-1 provides requirements for three LOP instrument functions:

Function 1, 4.16 kV Emergency Bus Undervoltage (Loss of Voltage);

Function 2, 4.16 kV Emergency Bus Undervoltage (Degraded Voltage); and

Function 3, 4.16 kV Emergency Bus Undervoltage (Annunciation).

For each LOP instrument function, Table 3.3.8.1-1 lists applicable number of required channels, surveillance requirements, and AVs. When one or more channels of Function 1 or 2 are inoperable, TS Actions require restoring the channel to Operable status within 1 hour1.157407e-5 days 2.777778e-4 hours 1.653439e-6 weeks 3.805e-7 months or declare the associated DG inoperable. When one or more channels of Function 3 are inoperable, TS Actions require verifying voltage on the associated emergency bus is <:: 3825 V once per hour or to declare the associated DG inoperable.

2.3 Reason for Proposed Change Revision of the requirements in TS 3.3.8.1 for LOP instrumentation is needed to reflect an electrical power system modification required to satisfy Unit 1 License Condition 2.C(11) and Unit 2 License Condition 2.C(3){i). Unit 1 License Condition 2.C(11) and Unit 2 License Condition 2.C(3)(i) require implementation of degraded voltage modifications that will eliminate use of manual actions as part of the HNP degraded voltage protection scheme.

A plant electrical power system modification will be performed to satisfy the license conditions per the implementation schedule specified in the Units 1 and 2 license conditions. The electrical power system modification, including the installation of the new degraded voltage instrumentation will be implemented for each unit's 4.16 kV emergency buses during the respective unit's refueling outage. SNC has evaluated the modification against the criteria of 10 CFR 50.59(c) and determined the facility modification does not require a license amendment pursuant to 10 CFR 50.90. However, a change to TS 3.3.8.1 is required as part of the implementation of that plant modification. Revision to HNP Unit 1 and Unit 2 TS 3.3.8.1 will be made in two stages to coincide with the staggered installation of the electrical power system modification over two refueling outages.

2.4 Description of Proposed Change The proposed amendment would revise Unit 2 License Condition 2.C(3)(i) and Unit 1 and Unit 2 TS 3.3.8.1 as follows (deleted text in strikeout and added text in italics):

Unit 2 License Condition 2.C(3)(i) states: "SNC shall implement the Degraded Voltage modifications to eliminate the manual actions in lieu of automatic degraded voltage protection to assure adequate voltage to safety-related equipment during design basis E1-5 to NL-18-0074 Basis for Proposed Change events for the Unit 2 4. 16 kV emergency buses by completion of the Unit 2 2019 Spring Outage, U2R25 and for the required Unit 1 4.16 kVemergency buses by completion of the Unit 1 2020 Spring Outage, U1 R29."

LCO 3.3.8.1 is revised to state, The LOP instrumentation for each Function in Table 3.3.8.1-1 shall be OPERABLE for each diesel generator (DG) required by LCO 3.8. 1, "AC Sources- Operating," and LCO 3.8.2, "AC Sources- Shutdown."

Applicability is revised to state, "MODES, 1, 2, and 3, When the-associated diesel generator fDGt is required to be OPERABLE. by LCO 3.8.2., "AC Seuroes Shutdown."

Condition A is revised to state, "One or more required channels inoperable for Functions 1 and 2."

Required Action B.1 is revised to state, "Verify voltage on associated Unit 1 4.16 kV bus is

3825 V."

Table 3.3.8.1-1 Column title is revised to, "Required Channels per Funotion Bus."

Function 2.a, 4.16 kV Emergency Bus Undervoltage (Degraded Voltage)- Bus Undervoltage, is revised to explicitly list the required emergency buses; and the AVs associated with Functions 2.a, "Bus Undervoltage" and 2.b, Time Delay," are revised with new calculated values individually specifying the bus undervoltage AV for each required 4.16 kV emergency bus.

I Title of Function 3 is revised to, "Unit 1 4.16 kV Emergency Bus Undervoltage (Annunciation)," and the number of required channels for Function 3 in Unit 2 Table 3.3.8.1-1 is changed from 1 to 2.

The proposed changes are shown in the marked-up and clean typed Unit 1 and Unit 2 TS pages provided in Attachments 1 and 2. Attachment 1 also provides a Unit 2 facility operating license marked-up page showing the associated license condition change. In addition, Attachment 3 provides, for information only, mark-ups of anticipated corresponding changes to affected TS Bases pages.

3.0 Technical Evaluation 3.1 Discussion of Changes The proposed change to Unit 2 License Condition 2.C(3)(i) is being made to address the staggered installation of the electrical power system modification that will eliminate the need for manual actions in lieu of automatic degraded voltage protection. Two of the Unit 1 4.16 kV emergency buses and associated DGs are required to support safety-related equipment (e.g. ,

low pressure coolant injection subsystems and the Standby Gas Treatment System) during design basis accidents. The degraded voltage instrumentation upgrade associated with these required buses will not be completed within the implementation schedule specified in the Unit 2 license condition. Therefore, the proposed change revises the Unit 2 license condition to include the implementation schedule for both units. The Unit 1 license condition is not affected by the proposed change because both units' degraded voltage instrumentation will be upgraded within the implementation schedule currently specified in the Unit 1 license condition. The E1-6 to NL-18-0074 Basis for Proposed Change additional text to the license condition is a clarification, does not alter the intent of the current license condition, and is considered administrative.

For the Unit 2 4.16 kV emergency buses, the proposed change to eliminate the loss of voltage annunciation requirements (i.e., TS Table 3.3.8.1-1, Function 3) and revise the degraded voltage instrumentation requirements (i.e., TS Table 3.3.8.1-1, Function 2) does not involve a physical change to the LOP instrumentation, nor does it change the safety function of the LOP instrumentation or the equipment supported by the LOP instrumentation. The AVs for Function 2a, "Bus Undervoltage," and Function 2b, Time Delay," include new calculated values individually specified for each required Unit 2 4.16 kV emergency bus and are more restrictive than the current requirements. These more restrictive requirements continue to ensure process variables, structures, systems, and components are maintained consistent with the safety analyses and licensing basis.

The proposed change to add the phrase, " .. .for each diesel generator (DG) required by LCO 3.8.1, "AC Sources - Operating," and LCO 3.8.2, "AC Sources- Shutdown,"" at the end of LCO 3.3.8.1 provides clarification the LOP instrumentation that is required for each unit, since both units require a portion of the other unit's offsite and onsite electrical power system to support shared unit loads and low pressure coolant injection subsystems. Currently, TS Table 3.3.8.1-1 does not specify requirements for each 4.16 kV emergency bus individually because the requirements are the same for all of the 4.16 kV emergency buses. However, the calculated degraded voltage instrumentation AVs that support the electrical power system modification are different for each bus based on the loading characteristics. Therefore, Table 3.3.8.1-1 is revised to specify AV requirements for each bus individually. As a result, the additional text to the LCO statement to only require the requirements associated with DGs required per LCO 3.8.1 and LCO 3.8.2 is a presentation preference, does not alter the meaning or intent of the current TS LCO, and is considered administrative.

The proposed change to the TS Applicability is an attendant change to the LCO revision and deletes Modes 1, 2, and 3 and reference to LCO 3.8.2. Because the LOP instrumentation supports the required DGs, the Applicability is revised consistent with the Applicability of TS 3.8.3, "Diesel Fuel Oil and Transfer, Lube Oil, and Starting Air," which also supports the required DGs. This proposed change is a presentation preference, does not alter the meaning or intent of the current TS Applicability, and is considered administrative.

Revising TS Table 3.3.8.1-1 Column title from Function to Bus more accurately reflects the LOP instrumentation design and is consistent with Table 3.3.8.1-1 of NUREG-1433, Revision 4 (Reference 2). The modified LOP instrumentation design includes two loss of voltage relays per bus (i.e., 6 per Function per unit) and three new solid state DVRs per bus (i.e., 8 per Function per unit). The proposed title change to the required channels column is considered administrative and has no effect on any safety analyses assumptions.

Function 3, 4.16 kV Emergency Bus Undervoltage (Annunciation) and associated requirements are revised to be applicable only to Unit 1 because manually transferring electrical power sources during a degraded voltage condition is no longer required for Unit 2 4.16 kV emergency buses to assure adequate voltage is supplied to safety-related equipment during design basis events. The proposed deletion of the Unit 2 loss of voltage annunciation requirements is offset by the more restrictive degraded voltage instrumentation AVs thereby providing an automatic emergency bus transfer to the alternate or emergency power supply in the event of a sustained degraded voltage condition. The number of required channels for Function 3 in Unit 2 Table 3.3.8.1-1 is changed from 1 to 2 consistent with the current Function 3 requirements in Unit 1 E1-7 to NL-18-0074 Basis for Proposed Change Table 3.3.8, 1-1. This more restrictive change ensures adequate annunciation channels are available to alert the operator of a degraded voltage condition on the required Unit 1 4.16 kV emergency buses.

The revision to TS 3.3.8.1 Condition A, revision to Required Action 8.1, and revision to the title of Table 3.3.8.1-1, Function 3 are concomitant changes as a result of the deletion of the 4.16 kV Emergency Bus Undervoltage (Annunciation) requirements associated with Unit 2. The addition of the word "required" to Condition A reflects the revised Unit 2 degraded voltage instrumentation logic. Only two of three Unit 2 degraded voltage instrument channels are required to be Operable in accordance with Table 3.3.8.1-1 Function 2.

3.2 Degraded Voltage Instrument Setpoints and Allowable Values The new AVs specified for the DVRs in Table 3.3.8.1-1 Function 2 have been chosen to assure adequate voltage to safety-related equipment during design basis events, eliminating reliance on manual actions from the degraded voltage protection scheme. Specifically, a loss of coolant accident (LOCA) signal concurrent with degraded bus voltage just below the DVR AV was assumed, such that sufficient voltage for proper operation of the safety-related loads is maintained until the DVRs actuate to separate the buses from the degraded offsite power source.

The methodology used in determining the AV's follows the guidelines listed in Generic Letter 79-36, "Adequacy of Station Electric Distribution Systems Voltages," (Reference 3) as supplemented in RIS 2011-12 (Reference 1). The loss of voltage annunciators will continue to alert the operator of a degraded voltage condition, however, they do not initiate automatic separation of the 4.16 kV buses from offsite power upon a LOCA actuation signal. Automatic separation of the buses from offsite power upon a LOCA actuation is not needed because the proposed DVR actuation voltage AVs have been calculated to maintain adequate voltage on the Class 1E buses with LOCA loads assumed. The proposed degraded voltage time delay was optimized to ensure that the Class 1E buses are separated from the offsite power system prior to damaging the safety related loads during sustained degraded voltage conditions while avoiding an inadvertent separation of safety-related buses from the offsite power system. New, higher alarm setpoints have been calculated for each bus that do not overlap with the new DVR AVs; therefore, separating a Class 1E bus from the preferred offsite power source at the low voltage alarm setpoint is not warranted.

The OVA actuation voltage and delay time settings are chosen to minimize nuisance tripping during normal operating conditions but still ensure that the voltage requirements of the safety-related loads are met without exceeding the maximum time delay assumed in the safety analyses. To address the effects of test equipment harmonics on offsetting relay operating points as described in NRC Information Notice 95-05, "Undervoltage Protection Relay Settings Out of Tolerance Due to Test Equipment Harmonics," dated January 20, 1995 (NRC Agencywide Documents Access and Management System (ADAMS) Accession No. ML031060397), the new DVRs include harmonic filters to preclude spurious actuations due to electrical bus harmonics (Reference 4).

Calculations were performed to determine the acceptable voltage operating range at the 4.16 kV emergency buses during normal and LOCA conditions, including transients due to motor starting and bus transfer. As stated in the HNP Unit 2 FSAR, Section 8.2, "Offsite Power System," the normal offsite system operating voltage range for Units 1 and 2 is 101.3% to 104.9% of 230 kV. The minimum expected voltage was calculated as the 4.16 kV emergency bus voltage which would occur during worst-case steady-state loading with a minimum 230-kV switchyard voltage of 101.3%.

E1-8 to NL-18-0074 Basis for Proposed Change The minimum required voltage (MRV) was determined as the greater of: a) the minimum acceptable steady-state voltage for normal operation and LOCA conditions of Class 1E loads, using maximum expected non-accident bus loading, b) the minimum pre-start voltage providing acceptable Class 1E motor starting (e.g. during LOCA group motor starting, using maximum expected accident loading, c) the minimum steady-state voltage providing acceptable Class 1E motor starting and operation for individual motors, using maximum expected accident loading, or d) the minimum voltage to the Class 1E motor control centers necessary for motor controller contactor pickup and equipment operation.

Electrical system voltage evaluations encompassed both Class 1E normal offsite power configurations and alternate offsite power configurations to determine worst case loading conditions. The evaluations included plant configurations with a single startup auxiliary transformer (SAT) out of service and the associated loads powered from the alternate SAT concurrent with safety related and non-safety related loads. Attachment 4 contains additional details on the methodology for determining the MRV.

The MRV value for each emergency bus was used in calculating the new OVA actuation voltage AVs proposed for Functions 2.a and 2.b of TS Table 3.3.8.1-1. Attachment 4 provides a description of the setpoint methodology from which the AVs were derived and includes criteria and assumptions used for determining the required voltage, voltage setpoints, and the time delay settings. The methodology follows the guidelines listed in Generic Letter 79-36 (Reference 3), as supplemented in RIS 2011-12 (Reference 1).

3.3 Human Factors Impacts Control room operators currently respond to an electrical degraded voltage condition using applicable alarm response procedures and take action in accordance with the applicable abnormal operations procedure. Operator actions include, but are not limited to, coordinating with the electrical grid system operator to maintain voltage above the minimum value per TS 3.3.8.1, Required Action 8.1, minimize activities that may have an impact of large load changes at the plant, and, if necessary, start the associated DG and transfer the affected 4.16 kV emergency buses to their associated DG.

Following implementation of the electrical power system modification, the alarm response procedures and the abnormal operations procedure associated with degraded system voltage will be modified to independently specify actions for alarm and automatic actuation response.

Operator response to a low voltage alarm will continue to include minimizing activities that may have an impact of large load changes at the plant, coordinating with the electrical grid system operator to restore the system voltage to within an acceptable range and, if necessary, start the associated DG and transfer the affected 4.16 kV emergency buses to their associated DG.

Following an automatic degraded voltage actuation, the applicable alarm response procedure will direct the operator to verify auto DG start, auto bus transfer to the DG, and verification of power available to the bus and associated loads.

The proposed license amendment changes the HNP licensing basis such that the degraded voltage protection design will rely upon the automatic actuation of the DVRs without crediting the current administrative controls, once the modifications are completed on each of the 4.16 kV emergency buses in each unit. HNP emergency operating procedures are not affected by the E1-9 to NL-18-0074 Basis for Proposed Change proposed change; therefore, SNC has determined that an emergency operating procedure control room task analysis is not required.

No changes to controls or displays in the control room are required to support the proposed license amendment. The loss of voltage and degraded voltage automatic actuations are currently annunciated in the control room and not modified as a result of the degraded voltage instrumentation modification or the proposed license amendment.

As part of implementation of the electrical power system modification, the plant reference simulator will be updated to reflect the modified electrical power system as required by paragraph (c) of 10 CFR 55.46, including the revised degraded voltage protection scheme instrument logic configuration and revision of the LOP instrumentation degraded voltage and annunciation actuation and reset setpoints and applicable operator training programs assessed in accordance with the systems approach to training process as required by paragraph (b) of 10 CFR 50.120.

4.0 Regulatory Evaluation 4.1 Applicable Regulatory Requirements/Criteria The loss of power (LOP) instrumentation associated with the Class 1E electrical power distribution system satisfies the criteria of 10 CFR 50.36, paragraph (c)(2)(ii), Criterion 3.

Automatic transfer of the Class 1E buses from their normal power source to the alternate or emergency power sources in the event of a degraded voltage condition is considered a primary success path to mitigate design basis accidents while connected to offsite power. Upon LOP instrumentation sensing a sustained degraded voltage condition on a Class 1E bus, the normal power is automatically disconnected from the bus and the alternate or emergency power is automatically connected to assure adequate voltage to safety related equipment during design basis accidents.

The proposed amendment continues to maintain requirements associated with structures, systems, and components that are part of the primary success path and actuate to mitigate the related design basis accidents and transients, including the LOP instrumentation.

Following implementation of the electrical power system modification, which includes providing automatic degraded voltage protection in lieu of manual actions to assure adequate voltage to safety related equipment during design basis accidents, the modified LOP instrumentation design will continue to comply with the applicable requirements of 10 CFR 50.55a(h)(2),

Protection and safety systems, and meet the requirements of the applicable Institute of Electrical and Electronics Engineers standards pursuant to 10 CFR 50.55a{2). The proposed amendment does not alter the design of the LOP instrumentation or any protection or safety system, rather, the proposed amendment incorporates attendant changes as a result of the electrical power system modification. Therefore, the protection and safety system design continues to meet the requirements of 10 CFR 50.55a.

The following principal design criterion is related to the Unit 1 LOP instrumentation design:

Criterion 39: Following implementation of the electrical power system modification, which includes providing automatic degraded voltage protection in lieu of manual actions E1-10 to NL-18-0074 Basis for Proposed Change to assure adequate voltage to safety related equipment during design basis accidents, the LOP instrumentation design will comply with the applicable requirements of Unit 1 principal design criterion 39. The proposed amendment does not alter the design of any onsite or offsite electric power system, including the LOP instrumentation, rather, the proposed amendment incorporates concomitant changes as a result of the electrical power system modification. The modified HNP electrical power system design, including the LOP instrumentation design changes, continues to assure the safety function for the offsite and standby auxiliary sources continue to provide electrical power to attain prompt shutdown and continued maintenance of the plant in a safe condition. The capacity of the offsite and onsite power sources continue to be independently adequate to accomplish the required engineered safety feature functions, assuming a failure of a single active component in each power system.

In addition, the following 10 CFR Part 50, Appendix A General Design Criteria (GDCs) are related to the Unit 1 and Unit 2 LOP instrumentation design:

GDC 17: Electrical power systems. Following implementation of the electrical power system modification, which includes providing automatic degraded voltage protection in lieu of manual actions to assure adequate voltage to safety related equipment during design basis accidents, the LOP instrumentation design will comply with the applicable requirements of GDC-17. The proposed amendment does not alter the design of any onsite or offsite electric power system, including the LOP instrumentation, rather, the proposed amendment incorporates concomitant changes as a result of the electrical power system modification. The modified HNP electrical power system design, including the LOP instrumentation design changes, continues to assure the safety function for the offsite and onsite electrical power systems continue 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 onsite electric power supplies and the onsite electric distribution system will continue to have sufficient independence, redundancy, and testability to perform their safety functions assuming a single failure.

The proposed amendment does not alter the design of the offsite circuits and these circuits will continue to be available in sufficient time following a loss of all onsite alternating current power supplies and the other offsite electric power circuits, to assure that specified acceptable fuel design limits and design conditions of the reactor coolant pressure boundary are not exceeded. The design of these circuits ensure at least one circuit is available within a few seconds following a loss-of-coolant accident to assure that core cooling, containment integrity, and other vital safety functions are maintained.

GDC 18: Inspection and testing of electric power systems. The proposed amendment does not alter the design of any onsite or offsite electric power system, including the LOP instrumentation, rather, the proposed amendment incorporates concomitant changes as a result of the electrical power system modification. Therefore, proposed amendment does not impact the HNP electrical power system design capability to test periodically; (1) the operability and functional performance of the components, including the loss of voltage and degraded voltage relays; and (2) the operability of the offsite and onsite electrical power systems as a whole and the full operation sequence that brings the systems into operation.

E1-11 to NL-18-0074 Basis for Proposed Change NRC Branch Technical Position (BTP) 8-6 (Reference 5) of NUREG 0800, Position B.1 contains criteria for undervoltage protection for sustained degraded voltage conditions, referred to as a "second level of undervoltage protection" additional to loss of offsite power, which is the first level. Position 8.1.b specifies two time delays for this second level of undervoltage protection.

The first time delay is for a degraded voltage alarm in the control room (a function which the emergency bus undervoltage relays will continue to provide), but Position 8.1.b.i also specifies immediate separation from offsite power in the event of the subsequent occurrence of a safety injection actuation signal (i.e., LOCA signal). The second time delay, per Position 8.1.b.ii, is for automatic separation from offsite power after a duration, limited such that Class 1E loads will not be damaged.

Actuation of the alarm relays does not initiate separation of the bus from offsite power upon a LOCA actuation signal as specified in BTP 8-6, Position B.1.b.i, but this automatic function is not needed at HNP because the proposed DVR actuation voltage AVs have been calculated to maintain adequate voltage on the Class 1E buses with LOCA loads assumed. New, higher alarm setpoints have been calculated for each bus that do not overlap with the new DVR AVs; therefore, separating a Class 1E bus from the preferred offsite power source at the alarm setpoint voltage as discussed in BTP 8-6, Position 8.1.b.i is not warranted.

The new DVR actuation voltage AV limits for each required 4.16 kV emergency bus, as proposed individually in Table 3.3.8.1-1 Function 2, are increased from the existing AV range specified in Table 3.3.8.1-1 so as to provide for fully automatic degraded voltage protection on each bus, eliminating the need for manual actions that are used in the existing HNP degraded voltage protection scheme.

4.2 No Significant Hazards Consideration Analysis Pursuant to 10 CFR 50.90, Southern Nuclear Operating Company (SNC) hereby requests an amendment to Edwin I. Hatch Nuclear Plant (HNP) Unit 1 Renewed Facility Operating License DPR-57 and Unit 2 Renewed Facility Operating License NPF-5. The proposed amendment revises Technical Specification (TS) 3.3.8.1, "Loss of Power (LOP) Instrumentation" to modify the instrument Allowable Values (AVs) for the Unit 2 4.16 kV emergency bus degraded voltage instrumentation and delete the annunciation requirements for the Unit 2 4.16 kV emergency bus undervoltage instrumentation. This proposed change is needed to reflect an electrical power system modification required to satisfy Unit 1 License Condition 2.C(11) and Unit 2 License Condition 2.C(3)(i). In addition, the proposed amendment revises the Unit 2 license condition to more accurately reflect its intent. The electrical power system modification, which SNC has evaluated independently, will eliminate use of manual actions as part of the HNP degraded voltage protection scheme.

SNC has evaluated whether a significant hazards consideration is involved with the proposed amendment(s) by focusing on the three standards set forth in 10 CFR 50.92, "Issuance of amendment," as discussed below:

E1-12 to NL-18-0074 Basis for Proposed Change

1. Does the proposed amendment involve a significant increase in the probability or consequences of an accident previously evaluated?

Response: No The proposed change incorporates concomitant changes to the LOP instrumentation requirements to reflect an electrical power system modification by deleting the unnecessary loss of voltage annunciation requirements and increasing the AVs for the degraded voltage protection instrumentation.

The proposed license change does not involve a physical change to the LOP instrumentation, nor does it change the safety function of the LOP instrumentation or the equipment supported by the LOP instrumentation. Automatic starting of the DGs is assumed in the mitigation of a design basis event upon a loss of offsite power. This includes transferring the normal offsite power source to an alternate or emergency power source in the event of a sustained degraded voltage condition. The LOP instrumentation continues to provide this capability and is not altered by the proposed license change. The proposed change does not adversely affect accident initiators or precursors including a loss of offsite power or station blackout. The revised LOP degraded instrumentation setpoints ensure that the Class 1E electrical distribution system is separated from the offsite power system prior to damaging the safety related loads during sustained degraded voltage conditions while avoiding an inadvertent separation of safety-related buses from the offsite power system. Additionally, the degraded voltage instrumentation time delay will isolate the Class 1E electrical distribution system from offsite power before the diesel generators are ready to assume the emergency loads, which is the limiting time basis for mitigating system responses to design basis accidents. As a result, the proposed change does not significantly alter assumptions relative to the mitigation of an accident or transient event and the proposed change does not involve a significant increase in the probability or consequences of an accident previously evaluated.

2. Does the proposed amendment create the possibility of a new or different kind of accident from any accident previously evaluated?

Response: No With respect to a new or different kind of accident, the proposed license change does not alter the design or performance of the LOP instrumentation or electrical power system; nor are there any changes in the method by which safety related plant structures, systems, and components (SSCs) perform their specified safety functions as a result of the proposed license amendment. The proposed change deletes the loss of voltage annunciation requirements and increases the AVs for the degraded voltage protection instrumentation as a result of an electrical power system modification, which SNC has evaluated independently of this proposed license amendment. The proposed license amendment will not affect the normal method of plant operation or revise any operating parameters. Additionally, there is no detrimental impact on the manner in which plant equipment operates or responds to an actuation signal as a result of the proposed license change. No new accident scenarios, transient precursor, failure mechanisms, or limiting single failures will be introduced as a result of this proposed E1-13 to NL-18-0074 Basis for Proposed Change change and the failure modes and effects analyses of SSCs important to safety are not altered as a result of this proposed change.

The process of operating and testing the LOP instrumentation uses current procedures, methods, and processes already established and currently in use and is not being altered by the proposed license amendment. Therefore, the proposed change does not constitute a new type of test.

Accordingly, the proposed change does not create the possibility of a new or different kind of accident from any previously evaluated.

3. Does the proposed amendment involve a significant reduction in a margin of safety?

Response: No Margin of safety is provided by the performance capability of plant equipment in preventing or mitigating challenges to fission product barriers under postulated operational transient and accident conditions. The proposed license change deletes the loss of voltage annunciation requirements and increases the AVs for the degraded voltage protection instrumentation as a result of an electrical power system modification, which SNC has evaluated independently of this proposed license amendment. The proposed deletion of the loss of voltage annunciation requirements is offset by the more restrictive degraded voltage instrumentation AVs thereby providing an automatic emergency bus transfer to the alternate or emergency power supply in the event of a sustained degraded voltage condition.

Therefore, the margin associated with a design basis or safety limit parameter are not adversely impacted by the proposed amendment and, thus the proposed change does not involve a significant reduction in a margin of safety.

Based on the above, SNC concludes that the proposed change does not involve a significant hazards consideration under the standards set forth in 10 CFR 50.92(c), and accordingly, a finding of "no significant hazards consideration" is justified.

4.3 Precedent This license amendment request is as a result of an electrical power system modification required to satisfy Unit 1 License Condition 2.C(11) and Unit 2 License Condition 2.C{3)(i) which were issued December 16, 2014 (Reference 6).

License amendments associated with degraded voltage and loss of voltage relay modifications were issued to Palo Verde Units 1, 2, and 3, dated April27, 2017, (NRC ADAMS Accession No. ML17090A164) and Joseph M. Farley Nuclear Plant, Units 1 and 2, dated November 17, 2016 (NRC ADAMS Accession No. ML16196A161 ). License amendments for changes to the degraded voltage relays and timers at Byron Station and at Braidwood Station (Exelon Generation Company, LLC) were issued December 21, 2015 (NRC ADAMS Accession No. ML15307A776).

E1-14 to NL-18-0074 Basis for Proposed Change 4.4 Conclusion In conclusion, based on the considerations discussed herein: (1) there is reasonable assurance that the health and safety of the public will not be endangered by operation in the proposed manner; (2) such activities will be conducted in compliance with the Commission's 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.

5.0 Environmental Consideration SNC has determined that the proposed amendment does not change a surveillance requirement. SNC has evaluated the proposed amendment to change the HNP Technical Specifications and determined that the proposed amendment does not involve (i) a significant hazards consideration, (ii) a significant change in the types or significant increase in the amounts of any effluents that may be released offsite, or (iii) a significant increase in the individual or cumulative occupational radiation exposure. Accordingly, the proposed amendment meets the eligibility criteria for categorical exclusion set forth in 10 CFR 51.22(c)(9).

Therefore, pursuant to 10 CFR 51.22(b), an environmental assessment or environmental impact statement is not required for the proposed amendment.

6.0 References

1. NRC Regulatory Issue Summary (RIS) 2011-12, "Adequacy of Station Electric Distribution System Voltages," Revision 1, dated December 29, 2011 (NRC ADAMS Accession No. ML113050583).

2. NRC NUREG-1433, "Standard Technical Specifications General Electric BWR/4 Plants,"

Volume 1 -Specifications, Revision 4.0 (NRC ADAMS Accession No. ML12104A192).

3. NRC Generic Letter 79-36, "Adequacy of Station Electric Distribution Systems Voltages,"

dated August 8, 1979.

4. NRC Information Notice 95-05, "Undervoltage Protection Relay Settings Out of Tolerance Due to Test Equipment Harmonics," dated January 20, 1995 (NRC ADAMS Accession No. ML031060397)

5. NRC Branch Technical Position 8-6, "Adequacy of Station Electric Distribution System Voltages," Revision 3, dated March 2007 (NRC ADAMS Accession No. ML070710478).

6. Letter from R. E. Martin, USNRC, to C.R. Pierce, SNC, "Edwin I. Hatch Nuclear Plant, Unit Nos. 1 and 2, Issuance of Amendments for Degraded Voltage Protection Modification Schedule (TAC Nos. MF0412 and MF0413)," dated December 16,2014 (NRC ADAMS Accession No. ML14328A323).

E1-15

Edwin I. Hatch Nuclear Plant, Units 1 and 2 License Amendment Request for Technical Specification 3.3.8.1 Regarding Degraded Voltage Protection Attachment 1 HNP Unit 2 Facility Operating License and Unit 1 and Unit 2 Technical Specifications Marked-Up Pages

- 6b-(h) TSTF-448. Control Room Habitability Upon implementation of the Amendments adopting TSTF-448, Revision 3, the determination of control room envelope (CRE) unfiltered air inleakage as required by SR 3.7.4.4, in accordance with TS5.5.14.c.(i), the assessment of CFE habitability as required by Specification 5.5.14.c.(ii), and the .

measurement of CRE pressure as required by Specification 5.5".14.d, shall be considered met. Following implementation:

i) The first performance of SR 3.7.4.4, in accordance with Specification 5.5.14.c.(i), shall be within the next 18 months.

ii) The first performance of the periodic assessment of CFRE habitability, Specification 5.5.14.c.(ii), shall be within 3 years, plus the 9-month Allowance of $R .3.0.2, ofthe next successful tracer gas test.

iii) The first performance of the periodic measurement of CRE pressure, Specification 5.5.14.d, shall be within 24 months, plus the 6 months allowed by SR 3.0.2, from the date of the most recent successful pressure measurement test.

and for the required for the Unit 2 4.16 kV Unit 1 4.16 kV (i) Degraded Voltage Protection emergency buses by completion of the Unit SNC shall implement the Degraded Voltage modificat ons to eliminate the 1 2020 Spring Outage, manual actions in lieu of automatic degraded voltage rotection to assure U1R29 adequate voltage to safety-related equipment during esign basis events completion of the Unit 2 2019 Spring Outage, U2R2 .

D. This renewed license is subject to the following antitrust conditions:

(1) As used herein:

(a) "Entity" means any financially responsible person, private or public corporation, municipality, county, cooperative, association, joint stock association or business trust, owning, operating or proposing to own or operate equipment or facilities within the state of Georgia (other than Chatham, Effingham, Fannin, Towns and Uniton Counties) for Renewed License No. NPF-5 Amendment No. 215

LOP Instrumentation 3.3.8.1 3.3 INSTRUMENTATION 3.3.8.1 Loss of Power (LOP) Instrumentation LCO 3.3.8.1 The LOP instrumentation for each Function in Table 3.3.8.1-1 shall be OPERABLE. for each diesel generator (DG) required by LCO 3.8.1, "AC Sources- Operating," and LCO 3.8.2, "AC Sources- Shutdown."

APPLICABILITY: MODES 1, 2, and 3, When tRe associated diesel !':)enerator (DG1 is required to be OPERABLE~(""")

by LCO 3.8.2, ",A,C Sources Shutdown." '-t.J ACTIONS

-----------N 0 TE--------------------------------------------------------

Separate Condition entry is allowed for each channel.

CONDITION REQUIRED ACTION COMPLETION TIME required ~<

A. One or mar channels A.1 Restore channel to 1 hour1.157407e-5 days 2.777778e-4 hours 1.653439e-6 weeks 3.805e-7 months inoperable for Functions 1 OPERABLE status.

and 2.

B. One or more channels B.1 Verify voltage on Once per hour inoperable for Function 3. associated 4.16 kV bus is~ 3825 Unit 1

c. Required Action and C.1 Declare associated DG Immediately associated Completion inoperable.

Time not met.

HATCH UNIT 1 3.3-66 Amendment No. 266 I

LOP Instrumentation 3.3.8.1 Table 3.3.8.1-1 (page 1 of 1)

Loss of Power Instrumentation REQUIRED

~ CHANNELS PER SURVEILLANCE ALLOWABLE FUNCTION ~ F'UNCTION REQUIREMENTS VALUE

1. 4.16 kV Emergency Bus Undervoltage (Loss of Voltage)

a. Bus Undervoltage 2 SR 3.3.8.1.2 2:2800 v SR 3.3.8.1.3 SR 3.3.8.1 .4

b. Time Delay 2 SR 3.3.8.1.2 s 6.5 seconds SR 3.3.8.1.3 SR 3.3.8.1.4

2. 4.16 kV Emergency Bus Undervoltage (Degraded Voltage)

1) Bus 1E L------1

!!. 3280V

a. Bus Undervoltage 2) Bus 1F 2 SR 3.3.8.1 .2 !!. 3280V

3) Bus 1G SR 3.3.8.1.3

4) Bus 2E !!. 3280V SR 3.3.8.1.4

5) Bus 2G !!, 3952V

b. Time Delay SR 3.3.8.1 .2 21 .5 SOGORGS !!. 3892V 2 li

~ 1) Unit 1 Buses SR 3.3.8.1.3 SR 3.3.8.1.4

~, ~ 2)Unit2Buses s 21 .5 seconds

3. 4.16 kV Emergency Bus Undervoltage s 9.8 seconds (Annunciation)

a. Bus Undervoltage 2 SR 3.3.8.1.1 2:3825 v SR 3.3.8.1.2 SR 3.3.8.1.3 SR 3.3.8.1.4

b. Time Delay 2 SR 3.3.8.1.2 s 65 seconds SR 3.3.8.1 .3 SR 3.3.8.1.4 HATCH UNIT 1 3.3-68 Amendment No. ~ I

LOP Instrumentation 3.3.8.1 3.3 INSTRUMENTATION 3.3.8.1 Loss of Power (LOP) Instrumentation LCO 3.3.8.1 The LOP instrumentation for each Function in Table 3.3.8.1-1 shall be OPERABLE. for each diesel generator (DG) required by LCO 3.8.1, "AC Sources- Operating," and LCO 3.8.2, "AC Sources- Shutdown."

APPLICABILITY:

Jt.O I

When tRe associated diesel generator (DG~ is required to be OPERABLE by LCO 3.8.2, "AC Sources Shutdown."

ACTIONS

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

Separate Condition entry is allowed for each channel.

_CONDITION REQUIRED ACTION COMPLETION TIME J. 0 d 1 requ1re ~I A. "Cfne or more hannels A.1 Restore channel to 1 hour1.157407e-5 days 2.777778e-4 hours 1.653439e-6 weeks 3.805e-7 months inoperable for Functions 1 OPERABLE status.

and 2.

B. One or more channels B.1 Verify voltage on Once per hour inoperable for Function 3. associate~

1s ;;:: 3825 . Unit 1 C. Required Action and C.1 Declare associated DG Immediately associated Completion inoperable.

Time not met.

HATCH UNIT2 3.3-66 Amendment No. ~ I

LOP Instrumentation 3.3.8.1 Table 3.3.8.1-1 (page 1 of 1)

Loss of Power Instrumentation REQUIRED

~ CHANNELS PER SURVEILLANCE ALLOWABLE FUNCTION ~ FUNCTION REQUIREMENTS VALUE

1. 4.16 kV Emergency Bus Undervoltage (Loss of Voltage)

a. Bus Undervoltage 2 SR 3.3.8.1.2 ~ 2800V SR 3.3.8.1.3 SR 3.3.8.1.4

b. Time Delay 2 SR 3.3.8.1.2 s 6.5 seconds SR 3.3.8.1.3 SR 3.3.8.1.4

2. 4.16 kV Emergency Bus Undervoltage (Degraded Voltage)

1) Bus 2E

a. Bus Undervoltage 2) Bus 2F 2 SR 3.3.8.1 .2

3) Bus 2G SR 3.3.8.1.3 ?. 3952 v

4) Bus 1E SR 3.3.8.1.4 ?. 3892 v

5) Bus 1G ----- ?. 3892 v

b. Time Delay 2 SR 3.3.8.1.2 ! 21.6 seseA~s ?. 3280 V SR 3.3.8 .1.3 ?. 3280 v

1) Unit 2 Buses

'\l

~

SR 3.3.8.1.4

~ '":1 2) Unit 1 Buses

3. 4.16 kV Emergency Bus Un ervo !age ~ 9.8 seconds (Annunciation) ~ 21 .5 seconds

a. Bus Undervoltage SR 3.3.8.1.1 ~ 3825V SR 3.3.8.1.2 SR 3.3.8.1 .3 SR 3.3.8.1.4

b. Time Delay SR 3.3.8.1.2 s 65 seconds SR 3.3.8.1.3 SR 3.3.8.1.4 HATCH UNIT2 3.3-68 Amendment No. 24-G I

Edwin I. Hatch Nuclear Plant, Units 1 and 2 License Amendment Request for Technical Specification 3.3.8.1 Regarding Degraded Voltage Protection Attachment 2 HNP Unit 1 and Unit 2 Technical Specifications Clean-Typed Pages

LOP Instrumentation 3.3.8.1 3.3 INSTRUMENTATION 3.3.8.1 Loss of Power (LOP) Instrumentation LCO 3.3.8.1 The LOP instrumentation for each Function in Table 3.3.8.1-1 shall be OPERABLE for each diesel generator (DG) required by LCO 3.8.1 , "AC Sources- Operating," and LCO 3.8.2, "AC Sources- Shutdown."

APPLICABILITY: When associated DG is required to be OPERABLE.

ACTIONS

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

Separate Condition entry is allowed for each channel.

CONDITION REQUIRED ACTION COMPLETION TIME A. One or more required A.1 Restore channel to 1 hour1.157407e-5 days 2.777778e-4 hours 1.653439e-6 weeks 3.805e-7 months channels inoperable for OPERABLE status.

Functions 1 and 2.

B. One or more channels B.1 Verify voltage on Once per hour inoperable for Function 3. associated Unit 1 4.16 kV bus is

~ 3825 v.

C. Required Action and C.1 Declare associated DG Immediately associated Completion inoperable.

Time not met.

HATCH UNIT 1 3.3-66 Amendment No.

LOP Instrumentation 3.3.8.1 Table 3.3.8.1-1 (page 1 of 1)

Loss of Power Instrumentation REQUIRED CHANNELS SURVEILLANCE ALLOWABLE FUNCTION PER BUS REQUIREMENTS VALUE

1. 4.16 kV Emergency Bus Undervoltage (Loss of Voltage)

a. Bus Undervoltage 2 SR 3.3.8.1.2 ~ 2800 v SR 3.3.8.1.3 SR 3.3.8.1.4

b. Time Delay 2 SR 3.3 .8.1.2 s 6.5 seconds SR 3.3.8.1.3 SR 3.3.8.1.4

2. 4.16 kV Emergency Bus Undervoltage (Degraded Voltage)

a. Bus Undervoltage 2 SR 3.3.8.1.2 SR 3.3 .8.1.3 SR 3.3 .8.1.4

1) Bus 1E ~ 3280 v

2) Bus 1F ~ 3280 v

3) Bus 1G :::: 3280V

4) Bus 2E ~ 3952 v

5) Bus2G ~ 3892 v

b. Time Delay 2 SR 3.3.8.1.2 SR 3.3.8.1 .3 SR 3.3.8.1.4

1) Unit 1 Buses s 21 .5 seconds

2) Unit 2 Buses s 9.8 seconds

3. Unit 1 4 .16 kV Emergency Bus Undervoltage (Annunciation)

a. Bus Undervoltage 2 SR 3.3.8.1.1 ;;:: 3825 v SR 3.3.8.1.2 SR 3.3.8.1.3 SR 3.3.8.1.4

b. Time Delay 2 SR 3.3 .8.1.2 s 65 seconds SR 3.3.8.1.3 SR 3.3.8.1.4 HATCH UNIT 1 3.3-68 Amendment No.

LOP Instrumentation 3.3.8.1 3.3 INSTRUMENTATION 3.3.8.1 Loss of Power (LOP) Instrumentation LCO 3.3.8.1 The LOP instrumentation for each Function in Table 3.3.8.1-1 shall be OPERABLE for each diesel generator (DG) required by LCO 3.8.1, "AC Sources- Operating," and LCO 3.8.2, "AC Sources- Shutdown."

APPLICABILITY: When associated DG is required to be OPERABLE.

ACTIONS

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

Separate Condition entry is allowed for each channel.

CONDITION REQUIRED ACTION COMPLETION TIME A. One or more required A.1 Restore channel to 1 hour1.157407e-5 days 2.777778e-4 hours 1.653439e-6 weeks 3.805e-7 months channels inoperable for OPERABLE status.

Functions 1 and 2.

B. One or more channels B.1 Verify voltage on Once per hour inoperable for Function 3. associated Unit 1 4.16 kV bus is

~ 3825 V.

C. Required Action and C. 1 Declare associated DG Immediately associated Completion inoperable.

Time not met.

HATCH UNIT 2 3.3-66 Amendment No.

LOP Instrumentation 3.3.8.1 Table 3.3.8.1-1 (page 1 of 1)

Loss of Power Instrumentation REQUIRED CHANNELS SURVEILLANCE ALLOWABLE FUNCTION PER BUS REQUIREMENTS VALUE

1. 4.16 kV Emergency Bus Undervoltage (Loss of Voltage)

a. Bus Undervoltage 2 SR 3.3.8.1.2 ;:: 2800 v SR 3.3.8.1.3 SR 3.3.8.1.4

b. Time Delay 2 SR 3.3.8.1.2 :5 6.5 seconds SR 3.3.8.1 .3 SR 3.3.8.1.4

2. 4.16 kV Emergency Bus Undervoltage (Degraded Voltage)

a. Bus Undervoltage 2 SR 3.3.8.1.2 SR 3.3.8.1.3 SR 3.3.8.1.4

1) Bus 2E ;:: 3952 v

2) Bus 2F ;:: 3892 v

3) Bus2G <:: 3892V

4) Bus 1E ~ 3280V

5) Bus 1G ;:: 3280 v

b. Time Delay 2 SR 3.3.8.1.2 SR 3.3.8.1.3 SR 3.3.8.1.4

1) Unit 2 Buses :5 9.8 seconds

2) Unit 1 Buses :5 21 .5 seconds

3. Unit 1 4.16 kV Emergency Bus Undervoltage (Annunciation)

a. Bus Undervoltage 2 SR 3.3.8.1 .1 ;:: 3825 v SR 3.3.8.1 .2 SR 3.3.8.1.3 SR 3.3.8.1.4

b. Time Delay 2 SR 3.3.8 .1.2 :5 65 seconds SR 3.3.8.1.3 SR 3.3.8.1.4 HATCH UNIT 2 3.3-68 Amendment No.

Edwin I. Hatch Nuclear Plant, Units 1 and 2 License Amendment Request for Technical Specification 3.3.8.1 Regarding Degraded Voltage Protection Attachment 3 HNP Unit 1 and Unit 2 Technical Specifications Bases Marked-Up Pages (Information Only)

LOP Instrumentation B 3.3.8.1 B 3.3 INSTRUMENTATION B 3.3.8.1 Loss of Power (LOP) Instrumentation BASES BACKGROUND Successful operation of the required safety functions of the Emergency Core Cooling Systems (ECCS) is dependent upon the availability of adequate power sources for energizing the various components such as pump motors, motor operated valves, and the associated control components. The LOP instrumentation monitors the 4.16 kV emergency buses. Offsite power is the preferred source of power for the 4.16 kV emergency buses. If the monitors determine that insufficient power is available, the buses are disconnected from the offsite power sources and connected to the onsite diesel generator (DG) power sources .

Each 4.16 kV emergency bus has its own independent LOP instrumentation and associated trip logic. The voltage for each bus is monitored at two levels: 4.16 kV Emergency Bus Undervoltage Loss of Voltage and Degraded Voltage, howe*.*er, only the loss of Voltage Function is part of this LCO. The Loss of Voltage Function causes various bus transfers and disconnects and is monitored by two undervoltage relays for each emergency bus, whose outputs are arranged in a two-out-of-two logic configuration for aU affected

< Insert B 3.3.8 .1-1>

components except the DGs. The DG start logic configuration is one-out-of-two (Ref. 1). he channels include electronic equipment The Unit 1 LOP alarm (e.g ., trip units) that compares measured input signals with instrumentation is pre-established setpoints. When the setpoint is exceeded, the required as part of the channel output relay actuates, which then outputs a LOP trip signal to LCO . The Unit 2 LOP the trip logic.

alarm instrumentation is not required as part of Each 4.16 kV emergency bus has its own independent LOP alarm the LCO because the instrumentation to rovide an antici atory alarm and the initiation of LOP degraded voltage corrective measures to restore emerge cy bus voltages. The alarms protection scheme are set higher than the LOP trip relays. The alarm setpoints are automatically protects approximately mid*.vay bet\'Jeen the oaloulated minimum expeoted safety related loads in 'Joltage and the oaloulated minimum required voltage, based on the the event of a sustained maximum m<peoted operating (i.e., non bOCA) load oonditions. The degraded electrical grid alarm setpoints signify that adequate voltage is a..*ailable for normal voltage condition . operations. The LOP anticipatory alarms provide a total time delay of 65 seconds to reduoe the possibility of nuisance alarms, while fUnit7] 7 - - -p_e_rm itting prompt detection of potential low voltage conditions.

71

~ Eac~.16 kV emergency bus has a dedicated low voltage annunciator fed by two relays and their associated time delays. The logic for the annunciation function is arranged in a two-out-of-two configuration.

(continued)

HATCH UNIT 1 B 3.3-188 REVISION 85

Insert B 3.3.8.1-1 The Degraded Voltage Function causes the same bus transfers and disconnects. The Unit 1 Degraded Voltage Function is monitored by two inverse time undervoltage relays for each emergency bus whose outputs are arranged in a two-out-of-two logic configuration for supported components except the DGs. The start logic for the Unit 1 DGs, including the swing DG (DG 1B) is arranged in a one-out-of-two configuration (Ref. 1). The Unit 2 Degraded Voltage Function is monitored by three solid state undervoltage relays with fixed time delay for each emergency bus whose outputs are arranged in a two-out-of-three logic configuration for supported components except the DGs. The start logic for the Unit 2 DGs and the swing DG (DG 1B) is arranged in a one-out-of-three configuration (Ref. 1).

LOP Instrumentation B 3.3.8.1 BASES (continued)

APPLICABLE The LOP instrumentation is required for Engineered Safety Features SAFETY ANALYSES, to function in any accident with a loss of offsite power. The required LCO, and channels of LOP instrumentation ensure that the ECCS and other APPLICABILITY assumed systems powered from the DGs, provide plant protection in the event of any of the References 2, 3, and 4 analyzed accidents in which a loss of offsite power is assumed. The initiation of the DGs on loss of offsite power, and subsequent initiation of the ECCS, ensure that the fuel peak cladding temperature remains below the limits of 10 CFR 50.46.

Accident analyses credit the loading of the DG based on the concurrent loss of offsite power during a loss of coolant accident. The diesel starting and loading times have been included in the delay time associated with each safety system component requiring DG supplied

<Insert B 3.3.8.1-7> power following a loss of offsite power.

to restore the 4.16 kV emergenoy bus voltages or to initiate a plant shutdown . The required channels of LOP alarm instrumentation ensure the initiation of manual actions to protest the EGGS and other assumed systems from degraded voltage without initiating an unnecessary automatic disconnect from tho preferred offsite po't*ter source. The ooourrenoe of an undervoltage degraded \'oltage condition credits the manual actions to mitigate the condition and ensure plant safety is maintained.

10 CFR 50.36(c)(2)(ii)

The OPERABILITY of the LOP instrumentation is dependent upon the OPERABILITY of the individual instrumentation channel Functions specified in Table 3.3.8.1-1. Each Function must have a required number of OPERABLE channels per 4.16 kV emergency bus, with their setpoints within the specified Allowable Values. A channel is inoperable if its actual trip setpoint is not within its required Allowable Value. The setpoint is calibrated consistent with applicable procedures (nominal trip setpoint).

each Function in the Table The Allowable Values are specified for the 4.16 k\' Emergency Bus

~AEJE~:maee-+-tt~*I&A. Nominal trip setpoints are specified in the setpoint calculations. The nominal setpoints are selected, based on engineering judgment, to ensure that the setpoints do not exceed the Allowable Value between CHANNEL CALIBRATIONS. Operation with a trip setpoint less conservative than the nominal trip setpoint, but within the Allowable Value, is acceptable. Trip setpoints are those predetermined values of output and time delay at which an action (continued)

HATCH UNIT 1 B3.3-189 REVISION 85

Insert B 3.3.8.1-7 The Unit 1 LOP alarm instrumentation provides annunciation to alert operators of a degraded electrical grid voltage condition thereby ensuring initiation of manual actions to protect safety related equipment powered from Unit 1 4.16 kV emergency buses during a sustained degraded electrical grid voltage condition. The Unit 2 LOP degraded voltage instrumentation provides automatic protection of safety related equipment powered from Unit 2 4.16 kV emergency buses during a sustained degraded electrical grid voltage condition.

LOP Instrumentation B 3.3.8.1 BASES APPLICABLE should take place. The setpoints are compared to the actual process SAFETY ANALYSES, parameter (e.g., degraded voltage), and when the measured output LCO, and value of the process parameter exceeds the setpoint and time delay, APPLICABILITY the associated device (e.g ., trip relay) changes state.

(continued)

....H'te-'He-K¥-I::ffiGeA.IGJtaG4~eeJMeG-¥Gltaefe-tA&-seltaaiflts were

<Insert B 3 .3 .8.1-3> determined in accordance with the NRC staff positions contained in an NRC letter dated June 2, 1977, except that manual actions are credited for restoring bus voltages or initiating a plant shutdown...ffi..tRe range of 78.8 to 92% of 4.16 kV. The undervoltage degraded voltage setpoint represents a point on the inverse time characteristic curve for the relay. The anticipatory alarm setpoints are approximately midway between the lculated minimum expected voltage and the calculated minimum required voltage, based on maximum expected operating; i.e., non-LOCA, conditions.

The Specific Applicable Safety Analyses, LCO, and Applicability discussions are listed below on a Function by Function basis.

1. 4.16 kV Emergency Bus Undervoltage (Loss of Voltage)

Loss of voltage on a 4.16 kV emergency bus indicates that offsite power may be completely lost to the respective emergency bus and is unable to supply sufficient power for proper operation of the applicable equipment. Therefore, the power supply to the bus is transferred from offsite power to DG power when the voltage on the bus drops below the Loss of Voltage Function Allowable Values (loss of voltage with a short time delay). This ensures that adequate power will be available to the required equipment.

The Bus Undervoltage Allowable Values are low enough to prevent inadvertent power supply transfer, but high enough to ensure that power is available to the required equipment. The Time Delay Allowable Values are long enough to provide time for the offsite power supply to recover to normal voltages, but short enough to ensure that power is available to the required equipment.

Two channels of 4.16 kV Emergency Bus Undervoltage (Loss of Voltage) Function per associated emergency bus are only required to be OPERABLE when the associated DG is required to be OPERABLE to ensure that no single instrument failure can preclude the DG function. (Two channels input to eaoh of the three OGs.) (Refer to LCOs 3.8.1, "AC Sources- Operating," and 3.8.2, "AC Sources-Shutdown," for Applicability Bases for the DGs.)

(continued)

HATCH UNIT 1 B 3.3-199 REVISION 85

Insert B 3.3.8.1-3 The Allowable Values for the Unit 2 4.16 kV degraded voltage instrumentation are derived from the analytic limits, corrected for calibration, process, and some of the instrument errors. The trip setpoints are then determined accounting for the remaining instrument errors (e.g., drift). The trip setpoints derived in this manner provide adequate protection because instrumentation uncertainties, process effects, calibration tolerances, instrument drift, and severe environment errors (for channels that must function in harsh environments as defined by 10 CFR 50.49) are accounted for. The Allowable Values for the Unit 1 4.16 kV degraded voltage instrumentation

LOP Instrumentation B 3.3.8.1 BASES APPLICABLE 2. 4.16 kV Emergency Bus Undervoltage (Degraded Voltage)

SAFETY ANALYSES, LCO, and A reduced voltage condition on a 4.16 kV emergency bus indicates APPLICABILITY that, while offsite power may not be completely lost to the respective (continued) emergency bus, available power may be insufficient for starting large ECCS motors without risking damage to the motors that could disable the ECCS Function. Therefore, power supply to the bus is transferred from offsite power to onsite DG power when the voltage on the bus drops below the Degraded Voltage Function Allowable Values (degraded voltage with a time delay). This ensures that adequate power will be available to the required equipment.

The Bus Undervoltage Allowable Values are low enough to prevent inadvertent power supply transfer, but high enough to ensu e that sufficient power is available to the large ECCS motors. Th ime Delay Allowable Values are long enough for the offsite power supply to usually recover.

For Unit 1 power supplies, manual This minimizes the potential that short duration disturbances will adversely impact the availability of the offsite power supply. P"i't'ti:tAtJat actions are credited in the range of 78.8 to 92% of 4.16 kV to restore bus voltages or to initiate a plant shutdown. The range specified for manual actions indicates that sufficient power is available to the largo EGGS motors; howe*.'or, sufficient voltage for equipment at lower

!<Insert 8 3 .3 .8 . 1 _8 > ~ voltages required for bOCA conditions may not be a*.*ailable.

Two channels of 4.16 kV Emergency Bus Undervoltage (Degraded Voltage) Function per associated bus are only required to be OPERABLE when the associated DG is required to be OPERABLE to ensure that no single instrument failure can preclude the DG function .

(Two channels input to each of the three emergency buses and DGs.)

Refer to LCO 3.8.1 and LCO 3.8.2 for Applicability Bases for the DGs.

~ ~

~ 3~4.16 kV Emergency Bus Undervoltage (Anttoipatorv :1\larm)

~

=-"

A reduced voltage condition on a"4.16 kV emergency bus indicates that, while offsite power is adequate for normal operating conditions, available power may be marginal for some equipment required for LOCA conditions. Therefore, the anticipatory alarms actuate when the 4.16 kV bus voltages approach the minimum required voltage for normal; i.e., non-LOCA conditions. This ensures that manual actions will be initiated to restore the bus voltages or to initiate a plant shutdown.

(continued)

HATCH UNIT 1 B3.3-191 REVISION 85

Insert 8 3.3.8.1-8 The Unit 2 Time Delay Allowable Values are long enough to provide time for the offsite power supply to recover to normal voltages, but short enough to ensure that sufficient power is available to the required equipment.

LOP Instrumentation B 3.3.8.1 BASES APPLICABLE 3.

SAFETY ANALYSES, LCO, and APPLICABILITY

~

Two channels of .16 kV Emergency Bus Undervoltage (Antioipatory

~ Function per associated bus are only required to be OPERABLE when the associated DG is required to be OPERABLE~

(T*No ohannels input to eaoh of the three emergenoy buses.)

!<Insert B 3.3.8.1-9> I ACTIONS A Note has been provided to modify the ACTIONS related to LOP instrumentation channels. Section 1.3, Completion Times , specifies that once a Condition has been entered, subsequent divisions, subsystems, components, or variables expressed in the Condition, discovered to be inoperable or not within limits, will not result in separate entry into the Condition. Section 1.3 also specifies that Required Actions of the Condition continue to apply for each additional failure, with Completion Times based on initial entry into the Condition. However, the Required Actions for inoperable LOP instrumentation channels provide appropriate compensatory measures for separate inoperable channels. As such, a Note has been provided that allows separate Condition entry for each inoperable LOP instrumentation channel.

With one or mer hannels of Function 1 or 2 inoperable, the Function does not maintain initiation capability for the associated emergency bus. Therefore, only 1 hour1.157407e-5 days 2.777778e-4 hours 1.653439e-6 weeks 3.805e-7 months is allowed to restore the inoperable channel to OPERABLE status. The Required Action does not allow placing a channel in trip since this action will result in a DG initiation.

The Completion Time is intended to allow the operator time to evaluate and repair any discovered inoperabilities. The 1 hour1.157407e-5 days 2.777778e-4 hours 1.653439e-6 weeks 3.805e-7 months Completion Time is acceptable because it minimizes risk while allowing time for restoration or tripping of channels.

!<Insert B 3.3.8.1-1 0>

~1 aoh 4.16 kV bus has a dedioated annunoiator fed by two relays and their assooiated time delays in a two out of two Iogie oonfiguration .

Both relays and their assooiated time delays are required to be OPERABlE. Therefore , the loss of either required relay or time delay renders FunGtion d incapable of performing the intended funGtion .

(continued)

HATCH UNIT 1 B3.3-192 REVISION 85

Insert 8 3.3.8.1-9 to ensure that adequate annunciation channels are available to alert the operator of a degraded voltage condition on the Unit 1 4.16 kV emergency buses.

Insert 8 3.3.8.1-10 With one or more Function 3 channels per bus inoperable, annunciation capability may not be available to alert the operator of a degraded voltage condition on the Unit 1 4.16 kV emergency buses.

LOP Instrumentation B 3.3.8.1 BASES SURVEILLANCE SR 3.3.8.1.4 (continued)

REQUIREMENTS The system functional testing performed in LCO 3.8.1 and LCO 3.8.2 overlaps this Surveillance to provide complete testing of the assumed safety functions.

The Surveillance Frequency is controlled under the Surveillance Frequency Control Program.

REFERENCES 1. FSAR, Section 8.4 .

2. FSAR, Section 4.8.

3. FSAR, Section 6.5.

4. FSAR, Chapter 14.

&: NRC No. 93 102, "Final Polioy StateRlent on Teshnioal Speoifioation IRlproveRlents," July 23, 1993.

HATCH UNIT 1 B 3.3-195 REVISION 85 I

LOP Instrumentation B 3.3.8.1 B 3.3 INSTRUMENTATION B 3.3.8.1 Loss of Power (LOP) Instrumentation BASES BACKGROUND Successful operation of the required safety functions of the Emergency Core Cooling Systems (ECCS) is dependent upon the availability of adequate power sources for energizing the various components such as pump motors, motor operated valves, and the associated control components. The LOP instrumentation monitors the 4.16 kV emergency buses. Offsite power is the preferred source of power for the 4.16 kV emergency buses. If the monitors determine that insufficient power is available, the buses are disconnected from the offsite power sources and connected to the onsite diesel generator (DG) power sources.

Each 4.16 kV emergency bus has its own independent LOP instrumentation and associated trip logic. The voltage for each bus is monitored at two levels: 4.16 kV Emergency Bus Undervoltage Loss of Voltage and Degraded Voltage, however, only the Loss of Voltage Function is part of this LCO. The Loss of Voltage Function causes various bus transfers and disconnects and is monitored by two undervoltage relays for each emergency bus, whose outputs are arranged in a two-out-of-two logic configuration for all-affected

components except t e DGs. The DG start logic configuration is one-out-of-two (Ref. 1). he channels include electronic equipment The Unit 1 LOP alarm (e.g., trip units) that compares measured input signals with instrumentation is pre-established setpoints. When the setpoint is exceeded, the required as part of the channel output relay actuates, which then outputs a LOP trip signal to LCO. The Unit 2 LOP the trip logic.

alarm instrumentation is not required as part of Each 4.16 kV emergency bus has its own independent LOP alarm the LCO because the instrumentation to provide an anticipatory alarm and the initiation of LOP degraded voltage corrective measures to restore emerg cy bus voltages. The alarms protection scheme are set higher than the LOP trip relays. Tt:le alarm setpoints are automatically protects approximately midway between the calculated minimum expected safety related loads in volta§e and the calculated minimum required voltage, based on the the event of a sustained mal<imum expected operating (i.e., non bOCA) load conditions. The degraded electrical grid alarm setpoints signify that adequate voltage is available for normal voltage condition. operations. Tho LOP anticipatory alarms provide a total time delay of 65 seoonds to reduce tt:le possibility of nuisance alarms, while permitting prompt detection of potential IS\*: voltage conditions.

~-------:-~

~ Eac~. 16 kV emergency bus has a dedicated low voltage annunciator fed by two relays and their associated time delays. The logic for the annunciation function is arranged in a out-of-two configuration. two (continued)

HATCH UNIT2 B 3.3-188 REVISION 96

Insert B 3.3.8.1-1 The Degraded Voltage Function causes the same bus transfers and disconnects. The Unit 1 Degraded Voltage Function is monitored by two inverse time undervoltage relays for each emergency bus whose outputs are arranged in a two-out-of-two logic configuration for supported components except the DGs. The start logic for the Unit 1 DGs, including the swing DG (DG 1B) is arranged in a one-out-of-two configuration (Ref. 1). The Unit 2 Degraded Voltage Function is monitored by three solid state undervoltage relays with fixed time delay for each emergency bus whose outputs are arranged in a two-out-of-three logic configuration for supported components except the DGs. The start logic for the Unit 2 DGs and the swing DG (DG 1B) is arranged in a one-out-of-three configuration (Ref. 1).

LOP Instrumentation 8 3.3.8.1 BASES (continued)

APPLICABLE The LOP instrumentation is required for Engineered Safety Features SAFETY ANALYSES, to function in any accident with a loss of offsite power. The required LCO, and channels of LOP instrumentation ensure that the ECCS and other APPLICABILITY assumed systems powered from the DGs, provide plant protection in the event of any of the Reference 2, 3, and 4 analyzed accidents in which a loss of offsite power is assumed. The initiation of the DGs on loss of offsite power, and subsequent initiation of the ECCS, ensure that the fuel peak cladding temperature remains below the limits of 10 CFR 50.46.

Accident analyses credit the loading of the DG based on the concurrent loss of offsite power during a loss of coolant accident. The diesel starting and loading times have been included in the delay time associated with each safety system component requiring DG supplied

<Insert B 3.3.8 .1-2> power following a loss of offsite power.

to rostor:e the 4.16 kV emer§enoy bus volta§es or to initiate a plant shutdown . The requirod channels of LOP alarm instrumentation ensure the initiation of manual actions to protect the EGGS and other assumed systems from degraded voltage without initiating an unnecessary automatic disconnect from the preferred offsite power source. The occurrence of an undef\*olta§e degraded voltage condition creElits the manual actions to mitigate the conElition and ensure plant safety is maintained.

The OPERABILITY of the LOP instrumentation is dependent upon the OPERABILITY of the individual instrumentation channel Functions specified in Table 3.3.8.1-1. Each Function must have a required number of OPERABLE channels per 4.16 kV emergency bus, with their setpoints within the specified Allowable Values. A channel is inoperable if its actual trip setpoint is not within its required Allowable Value. The setpoint is calibrated consistent with applicable procedures (nominal trip setpoint).

each Function in the Table The Allowable Values are specified for the 4.16 kV Emergenoy Bus Undervoltage r-unotion . Nominal trip setpoints are specified in the setpoint calculations. The nominal setpoints are selected, baseEl on engineering juElgmont, to ensure that the setpoints do not exceed the Allowable Value between CHANNEL CALIBRATIONS. Operation with a trip setpoint less conservative than the nominal trip setpoint, but within the Allowable Value, is acceptable. Trip setpoints are those predetermined values of output and time delay at which an action (continued)

HATCH UNIT2 B 3.3-189 REVISION 96

Insert B 3.3.8.1-2 The Unit 2 LOP degraded voltage instrumentation provides automatic protection of safety related equipment powered from Unit 2 4.16 kV emergency buses during a sustained degraded electrical grid voltage condition. The Unit 1 LOP alarm instrumentation provides annunciation to alert operators of a degraded electrical grid voltage condition thereby ensuring initiation of manual actions to protect safety related equipment powered from Unit 1 4.16 kV emergency buses during a sustained degraded electrical grid voltage condition.

LOP Instrumentation B 3.3.8.1 BASES APPLICABLE should take place. The setpoints are compared to the actual process SAFETY ANALYSES, parameter (e.g., degraded voltage), and when the measured output LCO, and value of the process parameter exceeds the setpoint and time delay, APPLICABILITY the associated device (e.g., trip relay) changes state.

(continued)

The 4.16 kV undervoltage degraded voltage trip setpoints were

~etermined in accordance with the NRC staff positions contained in l<lnsert B 3.3.8.1-3> an NRC letter dated June 2, 1977, except that manual actions are credited for restoring bus voltages or initiating a plant shutdown-fn....tRe range of 78.8 to Q2% of 4.16 kV. The undervoltage degraded voltage setpoint represents a point on the inverse time characteristic curve for the relay. The anticipatory alarm setpoints are approximately midway between the lculated minimum expected voltage and the calculated minimum required voltage, based on maximum expected operating; i.e., non-LOCA, conditions.

The specific Applicable Safety Analyses, LCO, and Applicability discussions are listed below on a Function by Function basis.

1. 4.16 kV Emergency Bus Undervoltage (Loss of Voltage)

Loss of voltage on a 4.16 kV emergency bus indicates that offsite power may be completely lost to the respective emergency bus and is unable to supply sufficient power for proper operation of the applicable equipment. Therefore, the power supply to the bus is transferred from offsite power to DG power when the voltage on the bus drops below the Loss of Voltage Function Allowable Values (loss of voltage with a short time delay). This ensures that adequate power will be available to the required equipment.

The Bus Undervoltage Allowable Values are low enough to prevent inadvertent power supply transfer, but high enough to ensure that power is available to the required equipment. The Time Delay Allowable Values are long enough to provide time for the offsite power supply to recover to normal voltages, but short enough to ensure that power is available to the required equipment.

Two channels of 4.16 kV Emergency Bus Undervoltage (Loss of Voltage) Function per associated emergency bus are only required to be OPERABLE when the associated DG is required to be OPERABLE to ensure that no single instrument failure can preclude the DG function. (Two channels input to eaoh of the three DGs.) Refer to LCO 3.8.1, "AC Sources- Operating," and 3.8.2, "AC Sources-Shutdown," for Applicability Bases for the DGs.

(continued)

HATCH UNIT2 B 3.3-190 REVISION 96

Insert B 3.3.8.1-3 The Allowable Values for the Unit 2 4.16 kV degraded voltage instrumentation are derived from the analytic limits, corrected for calibration, process, and some of the instrument errors. The trip setpoints are then determined accounting for the remaining instrument errors (e.g., drift). The trip setpoints derived in this manner provide adequate protection because instrumentation uncertainties, process effects, calibration tolerances, instrument drift, and severe environment errors (for channels that must function in harsh environments as defined by 10 CFR 50.49) are accounted for. The Allowable Values for the Unit 1 4.16 kV degraded voltage instrumentation

LOP Instrumentation B 3.3.8.1 BASES APPLICABLE 2. 4.16 kV Emergency Bus Undervoltage (Degraded Voltage)

SAFETY ANALYSES, LCO, and A reduced voltage condition on a 4.16 kV emergency bus indicates APPLICABILITY that, while offsite power may not be completely lost to the respective (continued) emergency bus, available power may be insufficient for starting large ECCS motors without risking damage to the motors that could disable the ECCS function. Therefore, power supply to the bus is transferred from offsite power to onsite DG power when the voltage on the bus drops below the Degraded Voltage Function Allowable Values (degraded voltage with a time delay). This ensures that adequate power will be available to the required equipment.

The Bus Undervoltage Allowable Values are low enough to prevent inadvertent power supply transfer, but high enough to ensure that sufficient power is available to the large ECCS motors. +Re-Time Delay Allowable Values are long enough for the offsit power supply to usually recover.

<Insert B 3.3 .8.1-4 > 1--- - -- - -- - - - -- - - - ---J This minimizes the potential that short duration disturbances will adversely impact the availability of the offsite power supply. Manual For Unit 1 power actions are credited in the mnge of 78.8 to 92% of 4.16 kV to restore supplies to Unit 2 bus voltages or to initiate a plant shutdown. The range specified for required loads, manual actions indicates that sufficient pO'.tler is a*1ailable to the large manual EGGS motors; howe¥er, sufficient IJoltage for eq1:1ipment at lower

'IOitages FOquired for LOCI\ conditions may not be a¥ailable.

Two channels of 4.16 kV Emergency Bus Undervoltage (Degraded Voltage) Function per associated bus are only required to be OPERABLE when the associated DG is required to be OPERABLE to ensure that no single instrument failure can preclude the DG function .

(Two channels input to eaoh of the thFOe emergency buses and DGs.)

Refer to LCO 3.8.1 and LCO 3.8.2 for Applicability Bases for the DGs.

~~--~ ~--+rA~nnvuvn~c~ia~t~io~n~

~::r--A--re_d_u_c-ed--v-ol-ta_g_e_c_o_nd-i-tio_n_o_n-i\4.16 kV emergency bus indicates that, while offsite power is adequate for normal operating conditions, available power may be marginal for some equipment required for LOCA conditions. Therefore, the anticipatory alarms actuate when the 4.16 kV bus voltages approach the minimum required voltage for normal; i.e., non-LOCA conditions. This ensures that manual actions will be initiated to restore the bus voltages or to initiate a plant shutdown.

(continued)

HATCH UNIT2 B 3.3-191 REVISION 96

Insert B 3.3.8.1-4 The Unit 2 Time Delay Allowable Values are long enough to provide time for the offsite power supply to recover to normal voltages, but short enough to ensure that sufficient power is available to the required equipment. The Unit 1

LOP Instrumentation B 3.3.8.1 BASES J.---+~

APPLICABLE 3. 4.16 kV Emergency Bus Undervoltage U\ntisipatorv Alarm)

SAFETY ANALYSES, (continued)

LCO, and One channel ofthe 4.16 kV Emergency Bus Undervoltage (1\ntisipatory j-? Alarm) Funstion per the assosiated bus is only required to be APPLICABILITY

!<Insert B 3.3.8 .1-5>

OPERABLE when the assosiated DG is required to be OPERABLE.

(Two shannels input to cash of the three emergensy buses.)

ACTIONS A Note has been provided to modify the ACTIONS related to LOP instrumentation channels. Section 1.3, Completion Times, specifies that once a Condition has been entered, subsequent divisions, subsystems, components, or variables expressed in the Condition, discovered to be inoperable or not within limits, will not result in separate entry into the Condition. Section 1.3 also specifies that Required Actions of the Condition continue to apply for each additional failure, with Completion Times based on initial entry into the Condition. However, the Required Actions for inoperable LOP instrumentation channels provide appropriate compensatory measures for separate inoperable channels. As such, a Note has been provided that allows separate Condition entry for each inoperable LOP instrumentation channel.

With one or more channels of Function 1 or 2 inoperable, the Function does not maintain initiation capability for the associated emergency bus. Therefore, only 1 hour1.157407e-5 days 2.777778e-4 hours 1.653439e-6 weeks 3.805e-7 months is allowed to restore the inoperable channel to OPERABLE status. The Required Action does not allow placing a channel in trip since this action will result in a DG initiation.

The Completion Time is intended to allow the operator time to evaluate and repair any discovered inoperabilities. The 1 hour1.157407e-5 days 2.777778e-4 hours 1.653439e-6 weeks 3.805e-7 months Completion Time is acceptable because it minimizes risk while allowing time for restoration or tripping of channels.

!<Insert B 3.3.8.1-6> ~ B.1 Eash 4.16 kV bus has a dedioated annunoiator fed by t\ve relays and their associated time delays in a one out of two Iogie sonfiguration.

Only one relay and its assooiated time delay is required to be OPERi\BLE. Therefore, the loss of the required relay or time delay renders Funotion a inoapable of performing the intended function.

(continued)

HATCH UNIT 2 B 3.3-192 REVISION 96

Insert B 3.3.8.1-5 Two channels of Unit 1 4.16 kV Emergency Bus Undervoltage (Annunciation) Function per associated required emergency bus are only required to be OPERABLE when the associated DG is required to be OPERABLE to ensure that adequate annunciation channels are available to alert the operator of a degraded voltage condition on the required Unit 1 4.16 kV emergency buses.

Insert B 3.3.8.1-6 With one or more Function 3 channels per required bus inoperable, annunciation capability may not be available to alert the operator of a degraded voltage condition on the required Unit 1 4.16 kV emergency buses.

LOP Instrumentation 8 3.3.8.1 BASES SURVEILLANCE SR 3.3.8.1.4 (continued)

REQUIREMENTS The system functional testing performed in LCO 3.8.1 and LCO 3.8.2 overlaps this Surveillance to provide complete testing of the assumed safety functions.

The Surveillance Frequency is controlled under the Surveillance Frequency Control Program.

REFERENCES 1. FSAR, Section 8.3.1.

2. FSAR, Section 5.2.

3. FSAR, Section 6.3.

4. FSAR, Chapter 15.

&: NRC No. 93 102, "Final Policy Statement on Teehnical Specification Improvements," July 23, 1993.

HATCH UNIT 2 8 3.3-195 REVISION 96 I

Edwin I. Hatch Nuclear Plant, Units 1 and 2 License Amendment Request for Technical Specification 3.3.8.1 Regarding Degraded Voltage Protection Attachment 4 Summary of the HNP Loss of Power Instrumentation Setpoint Methodology to NL-18-0074 Summary of the HNP Loss of Power Instrumentation Setpoint Methodology Hatch Nuclear Plant Loss of Power Instrumentation Setpoint Methodology and Summary Calculations

1.0 INTRODUCTION

The purpose of this document is to provide a summary description of the Hatch Nuclear Plant (HNP) setpoint methodology used to determine the limiting trip setpoint (LTSP), nominal trip setpoints (NTSPs), allowable values (AVs), and as-left tolerance (ALT) for the loss of power (LOP) instrumentation in support of the HNP degraded voltage instrumentation modification that eliminates manual action *in lieu of automatic degraded voltage protection and change to the Unit 2 degraded voltage instrumentation requirements in Technical Specification (TS) 3.3.8.1 ,

"Loss of Power (LOP) Instrumentation." The modified degraded voltage protection scheme is part of an electrical power system modification that replaces the existing startup auxiliary transformers (SATs) and adds an additional SAT for each unit. The modification also reconfigures the electrical circuit paths between the SATs and the Class 1E electrical distribution system such that no more than two 4.16 kV emergency buses can be supplied by a single SAT. This new configuration will improve the electrical loading margin associated with each transformer and eliminate the reliance on one SAT supplying electrical power to three 4.16 kV emergency buses during normal or accident conditions when the other SAT is unavailable; thereby expanding the voltage operating range by which the DVRs can be set.

Installation of this plant modification will be performed over two refueling cycles. This degraded voltage instrumentation setpoint methodology summary report supports implementation of the Unit 2 portion of the electrical power system modification. An additional summary report will be developed at a later date to support the results of Unit 1 degraded voltage instrumentation setpoint calculations needed to support full implementation of the electrical power system modification. The Unit 1 degraded voltage instrumentation setpoint calculations will utilize the same methodology as described herein, unless otherwise described in the followup report.

The modified 4.16 kV emergency bus degraded voltage protection scheme consists of three initiation channels for each bus. Each channel consists of a degraded voltage relay (DVR) with fixed time delay. The logic output is arranged in a two-out-of-three logic configuration for supported components except the diesel generators (DGs). The DG start logic is arranged in a one-out-of-three configuration.

2.0 SETPOINT METHODOLOGY 2.1 Current Licensing Bases Instrument Setpoint Uncertainties As documented in the NRC Safety Evaluation (SE) for HNP Units 1 Amendment 232 and Unit 2 Amendment 174, dated July 12, 2002, which supported the extension of the operating cycle from 18 months to 24 months, the plant-specific instrument setpoint methodology is similar to that documented in General Electric topical report NEDC-31336, "General Electric Instrument Setpoint Methodology," (Reference 1). NEDC-31336 has been previously approved by the NRC staff.

A4-1 to NL-18-0074 Summary of the HNP Loss of Power Instrumentation Setpoint Methodology Setpoint Drift Monitoring and Trending As documented in the NRC SE for HNP Units 1 Amendment 232 and Unit 2 Amendment 174, Southern Nuclear Company (SNC) monitors and trends the HNP setpoint control program as follows:

Instruments with TS calibration surveillance frequencies are monitored and trended .

As-found and as-left calibration data are recorded for each calibration activity. This activity identifies occurrences of instruments found outside of their AV, or instruments whose performance is not as assumed in the drift or setpoint analysis.

When as-found conditions are outside the AV, an evaluation is performed to determine if the assumptions made to extend the calibration frequency are still valid, to evaluate the effect on plant safety.

In addition, the HNP trending program addresses setpoints forTS calibration surveillance frequencies extended to 24 months found to be outside of their leave-alone tolerance (LAT).

This LAT is based upon either added margin or a portion of the expected drift for the instruments. For the purposes of this document, the terms LAT and ALT are synonymous.

The HNP trending program requires that any time a setpoint value is found outside the LAT, an additional evaluation be performed to ensure that the instruments performance is still enveloped by the assumptions in the drift or setpoint analysis. The trending program also plots setpoint or transmitter as-found /as-left values to verify that the performance of the instruments is within expected boundaries and that adverse trends (i.e., repeated directional changes in as-found

/as-left data of smaller magnitudes) are detected and evaluated.

2.2 General HNP Setpoint Methodology The HNP setpoint methodology is described in SNC procedure, NMP-ES-033, "Setpoint Control Program," and implemented in SNC procedure NMP-ES-033-005, "Setpoint Control Program Hatch Setpoint Uncertainty Methodology and Scaling Instructions." (References 2 and 3). The SNC setpoint control program establishes three groups with Group 1 requiring the greatest rigor. Group 1 calculations are consistent with the calculation methodology of ISA-S67.04.01, "Setpoints for Nuclear Safety-Related Instrumentation," (Reference 4) and ISA-RP67.04.02, "Methodologies for the Determination of Setpoints for Nuclear Safety-Related Instrumentation,"

(Reference 5) and meet the 95/95 tolerance limit as identified in NRC Regulatory Guide (RG) 1.105, "Setpoints for Safety-Related Instrumentation," (Reference 6).

LOP instrumentation calculations associated with the 4.16 kV emergency bus degraded voltage and time delay instrument functions utilize Group 1 setpoint methodology. The degraded voltage and time delay instrument setpoints are derived from the design basis analysis values (i.e., analytical limit) and are corrected for sources of uncertainty as defined in the SNC Setpoint Control Program implementing procedure (Reference 3) .

Consistent with the NRC approved HNP setpoint methodology and ISA Standard 67.04 (References 2 and 5); there are two required setpoint margins. These are also the margins A4-2 to NL-18-0074 Summary of the HNP Loss of Power Instrumentation Setpoint Methodology specified in RG 1.105 (Reference 6). The first setpoint margin is between the analytical limit and the AV. This margin is dependent on the process measurement uncertainties, the inherent instrument accuracies and the calibration errors, but does not include error due to instrument drift. The analytical limit to AV margin corresponds to the required margin just after the instrument has been calibrated, and has no allowance for additional measurement errors that may occur during the time period between calibrations. The second setpoint margin is that between the analytical limit and the minimum NTSP (or LTSP). This margin includes errors used to determine the AV margin and adds an additional margin for instrument drift. The AV and minimum NTSP margins represent the minimum margins required by the instrument setpoint methodology to meet the minimum probability demonstration margin.

A spurious trip avoidance (STA) test may be performed for an instrument setpoint where there is a significant practical consequence to spurious trips, such as inadvertent scram or inadvertent device actuation. In some cases, the STA test includes analyses of anticipated operational transients to establish setpoints that reduce the probability of a scram or safety system actuation. The STA test is performed to assure that there is a greater than 95% probability of avoiding a spurious trip when the setpoint is at its limiting NTSP (i.e., LTSP) value towards the operating envelope limit due to device LATs.

In summary, the setpoint calculation process provides margins to assure that, due to measurement uncertainties, the analytical limit is not exceeded during operation, and that the AVis not exceeded between calibrations. In addition, the methodology also includes a quantitative test to assure with at least a 95% probability that the setpoint is far enough from the parameter value for normal operating envelope limit to avoid spurious trips.

The setpoint methodology calculates the accuracy or uncertainty of the measurement for each device in the measurement channel including the trip unit, which gives the final trip signal. This includes, as applicable:

Channel accuracy with trip environment conditions (AT)

Calibration error (C)

Channel drift (D)

Process measurement accuracy (PMA)

Primary element accuracy (PEA)

Environmental allowances (EA)

The methodology used for combining uncertainties for LOP degraded voltage instrumentation setpoints utilizes the square root sum of the squares (SRSS) taken at 2 sigma (cr) confidence level for random uncertainties. Margins are obtained by combining the relevant channel random errors using SRSS, and adding bias errors, as follows:

AV Margin= (1.645/2) x (AT2 + C2 + PMA2 + PEA2) 112 +Bias errors Minimum NTSP Margin= (1.645/2) x (AP + C2 + 0 2 + PMA2 + PEA2) 112 +Bias errors Random error values represent 2cr values, and the 1.645/2 factor is a statistical factor that converts a 2cr value to 1.645cr. Because setpoints are approached from one side (low to high for an increasing setpoint and high to low for a decreasing setpoint), 1.645cr corresponds to 95%

A4-3 to NL-18-0074 Summary of the HNP Loss of Power Instrumentation Setpoint Methodology probability for one-sided approaches for normal distributions. EA for environmentally qualified (EQ) components are obtained from the EQ datasheets and treated as a bias error.

The AV and NTSP are obtained by subtracting (or adding) the margin from the analytical limit, depending on whether the variable increases (or decreases) to the setpoint. Thus:

=

AV AL- AV Margin (for increasing setpoint).

AV = AL + AV Margin (for decreasing setpoint).

Minimum NTSP = AL- NTSP Margin (for increasing setpoint).

=

Maximum NTSP AL + NTSP Margin (for decreasing setpoint).

The AV is the limiting value at which an instrument trip setting may be found, when tested periodically, beyond which appropriate action must be taken. The AV is determined by the instrument calculations considering the maximum possible value for process measurement at which the analytical limit is protected. Maintaining the instrument channel within the AV ensures the analytical limit and associated design limits are protected. For the LOP degraded voltage instrumentation, the bounding upper and lower calculations is conservative with respect to the as-found tolerance (AFT) and therefore, the AFT is equal to the upper and lower AVs.

The following provides a simplified visual presentation of the above terms similar to the guidance of RG 1.105 (Reference 6):

HNP Setpoint Parameters ISA RP67.04.02 Parameters Minimum Expected Voltage Normal Operating Point Upper AV, LAT+ AV+, AFT+ ALT+

NTSP (Reset) NTSP Upper LAT- ALT-Lower LAT+ ALT+

NTSP (Trip) NSTP, LTSP Lower LAT- ALT-Minimum NTSP Margin Lower AV ------ AV-, AFT-Lower Analytical Limit A~M;J. ------- Analytical Limit Minimum Required Voltage ---------------- Safety/Design Limit 3.0

SUMMARY

OF LOP DEGRADED VOLTAGE INSTRUMENT CALCULATIONS The methodology used in determining the 4.16 kV emergency bus degraded voltage and time delay AV's uses the guidance in the SNC Setpoint Control Program procedures to the extent practicable and is consistent with the guidelines listed in NRC Generic Letter 79-36, "Adequacy A4-4 to NL-18-0074 Summary of the HNP Loss of Power Instrumentation Setpoint Methodology of Station Electric Distribution Systems Voltages," (Reference 7) as supplemented in NRC Regulatory Issue Summary 2011-12, "Adequacy of Station Electric Distribution System Voltages," (Reference 8).

3.1 Minimum Expected Voltage and Minimum Required Voltage Determination The safety-related 4.16 kV emergency bus voltage is maintained such that the resulting voltage at the safety-related loads powered downstream from each respective 4.16kV bus is between the minimum and maximum allowable device voltage during undervoltage grid conditions.

The modified electrical power system improves the operating voltage at the 4.16 kV emergency buses due to the additional transformer loading margin afforded by the modified power configuration to the Class 1E electrical distribution system. Based on a minimum 230-kV switchyard voltage of 101.3% specified in the HNP Unit 2 FSAR, Section 8.2, "Offsite Power System," the minimum expected voltage (MEV) of the safety related 4.16 kV emergency buses is determined assuming the worst-case steady-state loading condition. In addition, the minimum required voltage (MRV) is determined to ensure the safety related equipment can successfully actuate during design basis events.

The postulated electrical grid voltage is lowered until the safety-related equipment undervoltage limit is reached, at which point the corresponding 4.16kV emergency bus voltage is at the MRV.

Degraded voltage instrumentation calculations confirm the actuation setpoint is above the calculated MRV, which ensures voltages at safety-related equipment powered downstream from each respective safety-related 4.16kV bus remain above their minimum level during steady-state and motor starting conditions. Motors shall be able to successfully start and operate during design basis accident conditions with 4.16kV emergency bus voltage at the MRV.

Additionally, minimum voltage to the Class 1E motor control centers necessary for motor controller contactor pickup and equipment operation was considered to determine the MRV.

Motor operated valves (MOVs) were evaluated to ensure that the minimum voltage at the valve is adequate to produce the required thrust and torque as established in the HNP MOV Program ,

which address the items specified in NRC Generic Letter 89-10 (Reference 9) .

ETAP, Version 12.6.0N, power system software was used to simulate loss of coolant accident (LOCA) conditions with a concurrent degraded grid condition. The model was based on the modified electrical power system configuration of three SATs per unit and included loading from safety and non-safety-related loads. Following final configuration of each SAT and following overall installation of the electrical power system modification, the validity of the ETAP model will be confirmed by obtaining field measurements for normal loading and compared to the acceptance criteria in the degraded voltage instrumentation calculations.

To determine worst case electrical loading conditions during a LOCA, multiple ETAP cases were simulated using various offsite power configurations to supply the Class 1E electrical distribution system including normal and alternate offsite power configurations. Electrical system voltage evaluations included combinations of electrical system configurations with each Unit 2 SAT out of service and the associated loads (Class 1E and non-Class 1E loads) powered from the alternate SAT. Methods used to determine the corresponding bus kVA for the non-Class 1E loads and the Class 1E loads include:

A4-5 to NL-18-0074 Summary of the HNP Loss of Power Instrumentation Setpoint Methodology LOCA- Maximum field reading plus 2.5% for non-Class 1E buses .

Class 1E buses use maximum field readings, plus 2.5%, minus loads that trip on LOCA, plus loads that start on LOCA.

Maximum- Maximum field reading in kVA plus 2.5% for conservatism.

Minimum- Lowest normal, non-outage field reading .

Maintenance & Refueling - Use maintenance and refueling field readings .

LOCA with Motor Start- Same as LOCA and used for AC motor starting studies LOCA with MOV- Same as LOCA and used for AC MOV motor starting studies Maximum with MOV- Same as maximum and used for AC MOV motor starting studies Minimum with MOV- Same as minimum and used for AC MOV motor starting studies In each postulated ETAP case, the power grid was set to a specific value, as low as possible, such that relevant criteria are met. The specific power grid values were determined iteratively.

Postulated grid voltage was lowered until the safety-related equipment undervoltage limit was reached, at which point the corresponding voltages at the 4.16kV emergency buses are at the MRVs. The MRV evaluations included, steady state, individual and group motor starting scenarios, MOV evaluation, and control circuit evaluations.

Each safety-related 4.16kV emergency bus was evaluated separately with regards to the equipment powered by that bus and downstream distribution buses. With respect to the MEV evaluations, the limiting ETAP configurations for 4.16 kV emergency buses are as follows:

Bus 2E - LOCA with SAT 2E unavailable and bus 2B , 2E, and 2G loads powered from SAT 20 simultaneously.

Bus 2F- LOCA with SAT 2C unavailable and bus 20, 2E, and 2F loads powered from SAT 2E simultaneously.

Bus 2G - LOCA with SAT 2E unavailable and bus 2B, 2E, and 2G loads powered from SAT 20 simultaneously.

With respect to the MRV evaluations, the limiting ETAP configurations for 4.16 kV emergency buses are as follows :

Bus 2E - Steady state with SAT 2E unavailable and bus 2B, 2E, and 2G loads powered from SAT 20 simultaneously.

Bus 2F -Individual motor starting with SAT 2C unavailable and bus 20, 2E, and 2F loads powered from SAT 2E simultaneously.

Bus 2G - Steady state with SAT 2E unavailable and bus 2B, 2E, and 2G loads powered from SAT 20 simultaneously.

The resulting MEV and MRV for each Unit 2 4.16 kV emergency bus and the limiting loads at the MRV are shown in Table 3.1-1 assuming the worst case loading conditions.

A4-6 to NL-18-0074 Summary of the HNP Loss of Power Instrumentation Setpoint Methodology Table 3.1-1 -MRV for Unit 2 4160 V Safety Related Buses MEV MRV 4160V Emergency Bus (% 4160V) (VAC) (% 4160V) (VAC) Limiting Load 2E 99.65 4145.44 92.70 3856 .32 SPDS Node 7 AJC Recirc Pump 28 2F 99.75 4149.60 89.12 3707.39 Discharge Valve 2G 99.65 4145.44 91 .20 3793.92 Instrument Bus 2A 3.2 4.16 kV Emergency Bus Degraded Voltage- Bus Undervoltage Function Calculation Acceptance Criteria The undervoltage trip function shall be set as low as possible while maintaining a margin of at least 0.2% setting (in addition to the required AV margin) between the lower analytical limit and TS Table 3.3.8.1-1, Function 2.a Allowable Value.

The goal for determining the NTSP (trip) and NTSP (reset) for the undervoltage trip function is to set these values as low as possible while allowing a margin of at least 0.2% setting (in addition to the AV margin) between the lower analytical limit and lower AV.

Calculation Assumptions

DVRs have been operating for at least 10 minutes (warmup) .

Conservatively convert the bias term associated with the calibration equipment to% setting based on 120 VAC and applying it as a non bias term yields an instrument calibration accuracy of +/-0.584% setting

Drift analysis was performed on the as-found/as-left data gathered from past calibrations of the DVR alarm relays located in the same operating environment as the relays being addressed by this calculation. The result of this analysis was extended to 22.5 months in accordance with guidelines provided in industry standard ISA-RP67.04.02 (Reference 5) .

No calibration accuracy associated with the PTs monitoring the bus voltage.

PMA and PEA are not applicable to this application .

Test source used in calibrating the relays has less than 0.3% harmonic distortion.

Room temperature effect of 0.75% setting is used, which bounds the temperature range that the relays will be exposed to.

LAT for the undervoltage trip and reset is assumed to be equal to the reference accuracy for the undervoltage function.

Maximum voltage drop on the cables between the PT secondary and the DVR is determined to be negligible based on the nominal voltage of 120V.

A4-7 to NL~ 18~0074 Summary of the HNP Loss of Power Instrumentation Setpoint Methodology

Minimum control voltage is calculated to be available for the closing coils of the 4.16KV buses 1E, 1F, 1G, 2E, 2F and 2G breakers. Maximum control voltage is the maximum acceptable voltage specified for the close and trip function of the circuit breakers.

Radiation and seismic effects are assumed to be negligible (zero) .

Vendor does not specify either humidity or pressure environmental requirements. Therefore, variations in humidity or pressure are assumed to have no effect on the relay's performance.

Accuracy of the PTs monitoring the bus voltage is included.

Calibration methodology and maintenance and test equipment (M&TE) used to calibrate the subject DVRs will be the same as those currently used to calibrate the degraded grid alarm relays.

Calibration interval for the DVRs do not exceed 22.5 months (18 months+ 25%).

Undervoltage function of the relays will be set to reset at their minimum reset value of 0.5%

of setting.

Methodology Overview The uncertainty terms in this calculation are based on % setting. Because of this, an iterative process is used to determine the controlling settings for the relay. The goal for determining the LTSP (trip) and LTSP (reset) for the undervoltage trip function is to set the value as low as possible with margin between the lower analytical limit and lower AV. The total margin criterion is at least 0.2% setting plus the calculated AV margin.

Using the formulas described in Section 2.0, the undervoltage uncertainty terms (transformer accuracy, relay accuracy, loop accuracy, calibration accuracy and loop drift) are calculated and the minimum NTSP margin and AV margin are determined. The lower AV and NTSP (trip) are determined using the resulting AV margin and NTSP margin, respectively. The equations in Section 2.0 for determining the NTSP and AV for an increasing process are then used to determine the NTSP (reset) and upper AV.

At this point, the derived NTSP (reset) is analyzed to determine that enough margin exists between this setpoint and the upper AV to accommodate the LAT. This is accomplished by adding the LAT to the NTSP (reset) and verifying that the sum does not exceed the calculated upper AV. Because the sum of LAT and NTSP (reset) exceeds the calculated upper AV, the NTSP (reset) is adjusted to account for the LAT. This is done by subtracting the LAT from the upper AV, which results in an adjusted NTSP.

A STA check is conducted to assure with at least 95% probability that the NTSP (trip) is far enough from the normal operating envelope limit to avoid spurious trips. The resulting STA loop uncertainty was calculated and confirmed to satisfy the 95% probability criterion and therefore the NTSP (trip) is considered low enough to avoid spurious trips.

Additionally, the upper and lower degraded voltage instrumentation analytical limits were evaluated against the MEV and MRV, respectively to ensure the degraded voltage instrument AVs did not exceed these voltage boundaries.

A4~8 to NL-18-0074 Summary of the HNP Loss of Power Instrumentation Setpoint Methodology Allowable Values for Degraded Voltage - Bus Undervoltage Using the methodology and assumptions provided herein, the following shows the results of the Unit 2 4.16 kV bus degraded voltage instrument calculations. Table 3.2-1 shows the LAT for the PT primary and secondary voltages, which were derived from the instrument reference accuracy and rounded up. The LATs apply to each Unit 2 4.16 kV emergency bus.

Table 3.2-1, Bus Undervoltage Tolerances Calculation Voltage LAT Primary Voltage 4160 +/-7.0 VAC +/-0.1%

I Secondary Voltage 120 +/-0.2 VAC +/-0.1%

I The calculated lower analytical limit, trip and reset AVs and NTSPs, and upper operating limit for the 4.16 kV safety related degraded voltage instrumentation loops associated with Unit 2 4.16 kV emergency buses are shown in Table 3.2-2:

Table 3.2-2 -Allowable Values and Nominal Setpoints (Bus Undervoltage Function)

Bus Degraded Voltage- 2E 2E 2F 2F 2G 2G Undervoltage Primary Secondary Primary Secondary Primary Secondary Trip Voltage Voltage Voltage Voltage Voltage Voltage Upper Operating 4053.0 115.8 3993.5 114.1 3993.5 114.1 Limit (VAC)

Upper Operating 97.43 96.00 96.00 Limit (% setting)

AV Reset (VAC) 4011 114.6 3952 112.9 3952 112.9 NTSP Reset 4004 114.4 3945 112.7 3945 112.7 (VAC)

NTSP Trip (VAC) 3983 113.8 3924 112.1 3924 112.1 AV Trip (VAC) 3952 112.9 3892 111 .2 3892 111 .2 Lower Analytical 3902.0 111 .5 3843.0 109.8 3843.0 109.8 Limit (VAC)

Lower Analytical 93.80 92.38 92.38 Limit (% setting)

As shown in Tables 3.1-1 and 3.2-2, the calculated MEV and MRV bound the upper and lower analytical limits. Therefore, the degraded voltage instrument upper AV (reset) is below the MEV and the lower AV (trip) is above the MRV.

A4-9 to NL-18-0074 Summary of the HNP Loss of Power Instrumentation Setpoint Methodology 3.3 4.16 kV Emergency Bus Degraded Voltage- Time Delay Function Calculation Acceptance Criteria

Voltages at the safety-related equipment powered downstream from each respective safety-related 4.16kV emergency bus must remain above the MRV during steady-state and motor starting conditions.

With the 4160 V bus pre-start voltage at or below the MRV, LOCA motor starting transient time must be Jess than the DVR time delay setting, with tolerances, to mitigate spurious trips.

DVR time delay setting, with tolerances, must be Jess than the DG start time of 12 seconds to prevent an extended degraded grid condition.

DVR time delay setting, with tolerances, must be Jess than the minimum overcurrent relay trip time to prevent safety-related equipment from tripping during a degraded voltage condition .

Calculation Assumptions

DVR calibration limits are determined to be +/-0.5 seconds from the HNP surveillance test procedure for the degraded voltage alarm relays.

LOCA group motor safe stall times are greater than the DG start time and therefore not considered as a limiting criteria.

Loading on control power fuses from indicating lights is negligible.

Motor starters are assumed to draw inrush current continuously until the DVR trips or the control power fuse blows. This is conservative because actual inrush current would be reduced by a degraded voltage condition.

Methodology Overview ETAP Version 12.6.0N software package was used to develop the HNP electrical power system computer model used for the HNP Units 1 and 2 station auxiliary system and 4.16 kV emergency bus transfer studies. The results of these calculations were used as design inputs in the degraded voltage time delay calculations. Dynamic motor starting cases were developed using the modified HNP electrical system configuration. The LOCA group motor start study case was re-analyzed as a dynamic motor starting case to determine the LOCA motor starting transient time for each safety-related 4kV emergency bus.

LOCA motor starting transient time was calculated as the minimum time for the LOCA group motors to start and reach steady-state with the 4kV emergency bus pre-start voltage below the MRV. Motor protection settings were analyzed during the time period for which the voltage dropped below the MRV, but remains above the Joss of site power alarm relay setpoint.

The 230 kV source was used to model the grid voltage along with a Thevenin equivalent grid impedance of 100MVA base. This source voltage feeds the 230kV swing bus "System" and was set to 92% to obtain the desired voltage below the MRV at the 4160 V emergency bus being studied for each case.

A4-10 to NL-18-0074 Summary of the HNP Loss of Power Instrumentation Setpoint Methodology Overcurrent relays (OCRs) at the 4160 V LOCA group motors (i.e., low pressure coolant injection (LPCI) pump and core spray pump motors) were analyzed to verify degraded voltage effects on these motors during starting will not cause an OCR trip prior to a DVR trip. To account for degraded voltage, the locked rotor amperes (LRA) associated with each LOCA group motor was adjusted by multiplying the LRA times a percentage of 4160 Vat or less than the motor's respective electrical bus MRV. Each starting motor is conservatively assumed to stall continuously at this current until the time at which the OCR would trip. This time is determined from OCR plots using SKM software. Table 3.3-1 shows the overcurrent trip time of the Unit 2 LOCA group motors based on the adjusted LRA.

Table 3.3 Unit 2 LOCA Group Motors Overcurrent Trip Times Adjusted OCR Trip 4.16 kV LRA SMRV LRA Time Motor Name Bus Motor HP (amperes) (% 4160 V) (amperes) (sees.)

LPCI Pump 2A 1000 825 752 9.94 2E 91.10 Core Spray Pump 2A 1000 825 752 9.94 LCPI Pump 2C 1000 825 759 9.89 2F 92.03 LPCI Pump 20 1000 825 759 9.89 LPCI Pump 28 1060 746 688 10.60 2G 92.21 Core Spray Pump 28 1000 825 761 9.89 Thermal overloads for LOCA group motor operated valves (MOVs) were not analyzed because the thermal overloads are permanently bypassed to avoid a protective device trip. It has been determined that MOVs motors less than 10 HP, including five LOCA group MOVs, will not be damaged before 17 seconds. Other safety-related equipment is assumed to have a full load ride-through capability of at least 75% of nameplate voltage with duration of at least 30 seconds.

Below 75%, the loss of voltage relay is set to protect the safety-related equipment. Control power fuses for starting MOVs were also evaluated to ensure that they will not blow before the DVR trips.

Allowable Values for Degraded Voltage- Time Delay From the LOCA group motor transient plots, the motors were capable of starting and reaching full speed within 2.00 seconds. Therefore, a DVR time delay of 2.00 seconds is determined to be minimum time to avoid unnecessary automatic transfer of the loads to the DGs. The calculated analytical limits, AVs, NTSP, and LAT for the 4.16 kV safety related degraded voltage relay time delay associated with Unit 2 4.16 kV emergency buses are shown in Table 3.3-2.

A4-11 to NL-18-0074 Summary of the HNP Loss of Power Instrumentation Setpoint Methodology Table 3.3-2 -Allowable Values and Nominal Setpoints (Time Delay Function)

Bus Degraded Voltage 2E 2F 2G

- Time Delay Upper Analytical Limit 9.89 9.89 9.89 (sec)

Upper AV (sec) 9.81 9.81 9.81 NTSP (sec) 9.00 9.00 9.00 Lower AV (sec) 2.02 2.02 2.02 Lower Analytical Limit 2.00 2.00 2.00 (sec)

LAT (sec) +/- 0.5 +/- 0.5 +/- 0.5 4.0 TECHNICAL SPECIFICATION APPLICATION OF INSTRUMENT SETPOINTS The AVs for the Unit 2 4.16 kV Degraded Voltage Bus Undervoltage and Time Delay Functions in TS Table 3.3.8.1-1 (Functions 2.a and 2.b) were selected from the DVR trip AVs specified in Table 3.2-2 and the upper time delay AV specified in Table 3.3-2. These AVs ensure that the voltage requirements of the safety-related loads are met during a design basis accident without exceeding the maximum time delay assumed in the safety analyses. The 4.16 kV Degraded Voltage Bus Undervoltage and Time Delay Functions are demonstrated Operable by applying the following guidance during instrument Channel Calibrations:

If the instrument setting is found within the LAT, the results are recorded in the surveillance procedure and no further action is required for the instrument surveillance. If the instrument setting is found outside the LAT but conservative with respect to the TS AV, the channel is Operable and the instrument setting must be calibrated to the NTSP (within the LAT). If the instrument setting is found non-conservative to the TS AV, the channel is inoperable until the instrument setting is calibrated to the NTSP (within the LAT) and any evaluations necessary to return the channel to service are completed. The instrument setting may be more conservative than the LTSP provided the AFT (i.e., minimum NTSP margin) and LAT are applied to the actual instrument setting (i.e., actual NSTP) used to confirm channel performance.

5.0 REFERENCES

1. Letter from L. N. Olshan (NRC) to H. L. Sumner, Jr. (SNC), "Edwin I. Hatch Nuclear Plant, Units 1 and 2 Re: Issuance of Amendments (TAC Nos. MB2965 and MB2967)," dated July 12, 2002 (NRC ADAMS Accession No. ML022040085).

2. SNC procedure NMP-ES-033, "Setpoint Control Program," Version 7.0.

3. SNC procedure NMP-ES-033-005, "Setpoint Control Program Hatch Setpoint Uncertainty Methodology and Scaling Instructions," Version 6.1.

A4-12 to NL-18-0074 Summary of the HNP Loss of Power Instrumentation Setpoint Methodology

4. ISA-S67.04.01, "Setpoints for Nuclear Safety-Related Instrumentation," 2000.

5. ISA-RP67.04.02, "Methodologies for the Determination of Setpoints for Nuclear Safety-Related Instrumentation," 2000.

6. NRC Regulatory Guide 1.1 05, "Setpoints for Safety-Related Instrumentation," Revision 3, December 1999 (NRC ADAMS Accession No. ML993560062).

7. NRC Generic Letter 79-36, "Adequacy of Station Electric Distribution Systems Voltages,"

dated August 8, 1979.

8. NRC Regulatory Issue Summary (RIS) 2011-12, "Adequacy of Station Electric Distribution System Voltages," Revision 1, dated December 29, 2011 (NRC ADAMS Accession No. ML113050583).

9. NRC Generic Letter 89-10, "Safety-Related (1) Motor-Operated Valve Testing and Surveillance (Generic Letter 89-10)- 10 CFR 50.54(f)," dated June 28, 1989.

A4-13

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