ML19086A113

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Proposed License Amendment Request to Reduce Maximum EDG Steady State Voltage from 4580V to 4400V
ML19086A113
Person / Time
Site: North Anna  Dominion icon.png
Issue date: 03/18/2019
From: Sartain M D
Virginia Electric & Power Co (VEPCO)
To:
Document Control Desk, Office of Nuclear Reactor Regulation
References
19-012
Download: ML19086A113 (36)
v • d • e


Text

.) VIRGINIA ELECTRIC AND POWER COMPANY RICHMOND, VIRGINIA 23261 March 18, 2019 U.S. Nuclear Regulatory Commissi9n Attention:

Document Control Desk Washington, DC 20555 VIRGINIA ELECTRIC AND POWER COMPANY NORTH ANNA POWER STATION UNITS 1 AND 2 PROPOSED LICENSE AMENDMENT REQUEST TO Serial No.: NRNDEA Docket Nos.: License Nos.: 10 CFR 50.90 19-012 RO 50-338/339 NPF-4/7 REDUCE MAXIMUM EDG STEADY STATE VOLTAGE FROM 4580V TO 4400V Pursuant to 10 CFR 50.90, Virginia Electric and Power Company (Dominion Energy Virginia) is submitting a license amendment request to revise Technical Specifications (TS) 3.8.1, "AC Sources -Operating." The proposed change reduces the maximum voltage specified for certain Section 3.8.1 Surveillance Requirements associated with the Emergency Diesel Generators (EDGs). The changes are necessary to address conservatism in the subject TS surveillance requirements.

Conforming changes are also proposed to Technical Specifications Bases (TSB) B3.8.1. The non-conservative acceptance criteria in Technical Specification 3.8.1 are currently administratively controlled under a Standing Order to assure that plant safety is maintained.

This license amendment request is submitted in accordance with the guidance in NRC Administrative Letter 98-10 as a required license amendment request to resolve a non-conservative technical specific~tion.

As such, this is not a "voluntary request from a licensee to change its licensing basis" and should not be subject to "forward fit" considerations.

Information provided in the attachm~nts to this letter is summarized below: -Attachment 1 provides an ev~luation of the proposed TS changes. -Attachment 2 provides mark~d-up Technical Specifications pages. -Attachment 3 provides proposed Technical Specifications changes pages. -Attachment 4 provides mark~d-up and proposed Technical Specifications Bases changes pages (for information only). Dominion Energy Virginia has eval1:,1ated the proposed amendment and determined that it does not involve a significant hazc;trds consideration as defined in 10 CFR 50.92. The basis for this determination is inclL:1ded in Attachment

1. Dominion Energy Virginia has also determined that operation with the proposed change will not result in any significant increase in the amount of effluents that may be released offsite or any significant increase in individual or cumulative occupc;ttional radiation exposure.

Therefore, the proposed amendment is eligible for categoriq:11 exclusion from an environmental assessment as set forth in 10 CFR 51.22(c)(9).

Pur~uant to 10 CFR 51.22(b), no environmental impact statement or environmental assessment is needed in connection with the approval of the proposed change. D / µ ,1J/../(_

Serial No.19-012 Docket Nos.: 50-338/339 LAR -Reduce Max EOG SS Voltage Page 2 of 3 The proposed TS change has been reviewed and approved by the NAPS Facility Safety Review Committee.

Dominion Energy Virginia requests approval of the proposed amendment by February 28, 2020. Once approved, the amendment will be implemented within 90 days. Should you have any questions in regard to this submittal, please contact Diane Aitken at (804) 273-2694.

Sincerely, Mark D. Sartain Vice President

-Nuclear Engineering and Fleet Support COMMONWEALTH OF VIRGINIA COUNTY OF HENRICO The foregoing document was acknowledged before me, in and for the County and Commonwealth aforesaid, today by Mark D. Sartain, who is Vice President

-Nuclear Engineering and Fleet Support of Virginia Electric and Power Company. He has affirmed before me that he is duly authorized to execute and file the foregoing document in behalf of that Company, and that the statements in the document are true to the best of his knowledge and belief. Acknowledged before me this ;sr:ay of ..!11Ar'Cn, 2019. My Commission Expires: ~y 34 ,,10,XJ, . ~*XJ/iuL . Notary Public Commitments made in this letter: None VICKI L. HULL NOTARY PUBLIC REG. # 140542 *. COMMONWEALTH OF VIRGINIA '.r*r~ .~*;; MY COMMISSlON EXPIRES 5131/2022 Attachments:

1. Discussion of Change 2. Marked-up Technical Specifications Pages 3. Proposed Technical Specifications Pages Serial No.19-012 Docket Nos.: 50-338/339 LAR -Reduce Max EDG SS Voltage Page 3 of 3 4. Marked-up and Proposed Te.~hnical Specifications Bases Pages (for information only) cc: U.S. Nuclear Regulatory Commission

-Region II Marquis One Tower 245 Peachtree Center Avenue, NE Suite 1200 Atlanta, GA 30303-1257 State Health Commissioner Virginia Department of Health James Madison Building -7th floor 109 Governor Street Suite 730 Richmond, VA 23219 Mr. James R. Hall NRC Senior Project Manager -North Anna U.S. Nuclear Regulatory Commission One White Flint North Mail Stop 08 B 1-A 11555 Rockville Pike Rockville, MD 20852-2738 Ms. Karen Cotton-Gross NRC Project Manager -Surry U.S. Nuclear Regulatory Commission One White Flint North Mail Stop 08 G-9A 11555 Rockville Pike Rockville, MD 20852-2738 NRC Senior Resident Inspector North Anna Power Station Mr. Marcus Harris Old Dominion Electric Cooperative Innsbrook Corporate Center 4201 Dominion Blvd. Suite 300 Glen Allen, VA 23060 Attachment 1 DISCUSSION OF CHANGE Serial No.19-012 Docket Nos.: 50-338/339 Attachment 1 Page1of12 VIRGINIA ELECTRIC AND POWER COMPANY (DOMINION ENERGY VIRGINIA)

NORTH ANNA POWER STATION UNITS 1 AND 2 Table of Contents Serial No.19-012 Docket Nos.: 50-338/339 Attachment 1 Page 2 of 12 1.0

SUMMARY

DESCRIPTION

...................................................................................

3 2.0 DETAILED DESCRIPTION

....................................................................................

3 2.1 Existing System Description

...............................................................................

3 2.2 Current Technical Specifications (TS) Surveillance Requirements (SR) ............

3 2.3 Reason for Proposed Change ............................................................................

5 2.4 Description of Proposed Change ........................................................................

5 3.0 TECHNICAL EVALUATION

...................................................................................

5

4.0 REGULATORY EVALUATION

...............................................................................

? 4.1 Applicable Regulatory Requirements/Criteria

.....................................................

8 4.2 No Significant Hazards Consideration

................................................................

9 5.0 PRECEDENTS

....................................................................................................

10 6.0 ENVIRONMENTAL CONSIDERATION

...............................................................

11

7.0 CONCLUSION

S

.............................. , ....................................................................

11

8.0 REFERENCES

....................................................................................................

12 1.0

SUMMARY

DESCRIPTION Serial No.19-012 Docket Nos.: 50-338/339 Attachment 1 Page 3 of 12 Pursuant to 10 CFR 50.90, Virgiriia Electric and Power Company (Dominion Energy Virginia) requests Amendments tq North Anna Power Station Units 1 and 2 Facility Operating License Numbers 50-33? and 50-339, respectively, in the form of a change to the Technical Specifications (TS). The proposed change reduces the maximum voltage specified in several Section 3.8.1 Surveillance Requirements associated with the Emergency Diesel Generators (EPGs). The TS Bases Section B 3.8.1 will also be revised. 2.0 DETAILED DESCRIPTION

2.1 Existing

System Descriptit;m Each unit has two (2) independent 4160-volt emergency buses. Each bus provides power to 4000-volt motors and 4160/480-volt transformers which supply lower voltage equipment including 460-volt motors. Buses 1 H and 1 J are associated with Unit 1 and Buses 2H and 2J are associated with Unit 2. Each bus is designed to independently supply all safety-related equipment and auxiliaries necessary for safe shutdown of the reactor and all safety-related equipment necessary to mitigate the consequences of an accident.

Each unit has two 100% capacity emergency diesel generators (EDGs) that provide standby emergency ac power with adequate capacity to supply the safety-related equipment.

During the periods of interrupted preferred power, the EDGs automatically supply ac power to safety-related equipment.

The EDGs will automatically sta.rt if a safety injection signal is received, a 90% degraded voltage level is sensed for 56 seconds on the bus, or if approximately 74% voltage exists on the bus for 2 seconds. Following a safety injection start signal, the EOG will load if a 90% degraded voltage level exists for 7 .5 seconds. When approximately 74% voltage is sen~ed for 2 seconds, or if a degraded voltage condition exists, the emergency bus is isolated and load shedding begins. The EOG output breaker automatically closes onto the bus when a EOG output voltage reaches 95% of nominal, either of the normal offsite power supply breakers are open, limited residual voltage remains on the bus, and the EOG differential auxiliary relay is reset. An additional permissive exists for the EDGs output breakers requiring either of the bus-tie breakers to be open. The EDGs are load tested in accor9ance with the Technical Specifications.

2.2 Current

Technical Specific;ations (TS) Surveillance Requirements (SR) TS SR 3.8.1.2 Verify each required EOG ;,tarts from standby conditions and achieves steady state voltage~ 3740 Vand $ 4580 V, and frequency~

59.5 Hz ands 60.5 Hz.

TS SR 3.8.1.7 Serial No.19-012 Docket Nos.: 50-338/339 Attachment 1 Page 4 of 12 Verify each required EOG starts from standby conditions and achieves b. Steady state voltage~ 3740 V and::; 4580 V, and frequency~

59.5 Hz and::; 60.5 Hz. TS SR 3.8.1.9 Verify each required EOG rejects a load greater than or equal to its associated single largest post-accident load, and: b. Within 3 seconds following load rejection, the voltage is> 3740 V and < 4580 V; and TS SR 3.8.1.10 Verify on an actual or simulated loss of offsite power signal: c. Each required EOG auto-starts from standby condition and: 3. maintains steady state voltage 37 40 V and ::; 4580 V, 4. maintains steady state frequency~

59.5 Hz and ::; 60.5 Hz, and TS SR 3.8.1.11 Verify on an actual or simulated Engineered Safety Feature (ESF) actuation signal each LCO 3.8.1.b EOG auto-starts from standby condition and : d. Achieves steady state voltage~ 3740 V and::; 4580 V and frequency~

59.5 Hz and :5 60.5 Hz; TS SR 3.8.1.14 Verify each required EOG starts and achieves b. Steady state voltage~ 3740 V, and::; 4580 V and frequency~

59.5 Hz and :5 60.5 Hz. TSSR3.8.1.17 Verify on an actual or simulated loss of offsite power signal in conjunction with an actual or simulated ESF actuation signal: e. Each LCO 3.8.1.b EOG auto-starts from standby condition and: 3. achieves steady state voltage~ 3740 V and :5 4580 V, 4. achieves steady state frequency~

59.5 Hz and :5 60.5 Hz, and TSSR3.8.1.18 Verify when started simultaneously from standby condition, each LCO 3.8.1.b EOG achieves:

b. steady state voltage~ 3740 V and :5 4580 V, and frequency~

59.5 Hz and :5 60.5 Hz.

2.3 Reason

for Proposed Change Serial No.19-012 Docket Nos.: 50-338/339 Attachment 1 Page5of12 WCAP-17308-NP, "Treatment of Diesel Generator (DG) Technical Specification Frequency and Voltage Tolerances," was developed by Westinghouse and the PWR Owner's Group to determine the impact of EOG steady-state frequency and voltage variations on essential motor loads. In April 2017, the NRC issued its Final Safety Evaluation for WCAP-17308-NP, Revision 0. As described in WCAP-17308-NP, the wording of the EOG TS SR would allow steady-state EOG operation within the voltage and frequency limits specified.

The NRC has identified an apparent discrepancy during several Component Design Basis Inspections between the EOG TS SR and the application of these limits by many* licensees.

The licensee calculated emergency core cooling system flows sometimes assume a nominal voltage and frequency range and interpret the TS SR to correspond to short-term transient frequency and voltage excursions, and not steady-state.

The WCAP postulates that the confusion arises from historical emphasis on frequency and voltage transient recovery requirements speqified .in Regulatory Guide 1.9, "Selection, Design, Qualification, and Testing of Emergency Diesel Generator Units Used as Class 1 E Onsite Electric Power Systems at Nuclear Power Plants." Note that the voltage and frequency ranges may also impact EDG loading calculations and fuel consumption calculations.

At this time, calculations for North Anna Power Station (NAPS) currently include the full frequency range and the minimum allowable voltage; the maximum allowable voltage exceeds the existing Mechanical and Electrical systems analyses.

For steady-state conditions, the maximum allowable voltage (4580V) also exceeds the 4000-volt motor rating of +/- 10 percent (3600V to 4400V) for continuous operation.

System voltage drops at the 4160-volt level are not sufficient to limit the motor terminal voltage to 4400-volts. In addition, the 4400-volt limit is necessary to maintain maximum 480V system limits. 2.4 Description of Proposed Change Dominion Energy Virginia proposes to lower the maximum allowable steady-state voltage in the TS SRs describe.d in Section 2.2 above from 4580-volts to 4400-volts.

This change addresses concerns identified by WCAP-17308-NP and those regarding the maximum steady-state equipment voltage ratings. TS SR 3.8.1.9 verifies the maximum voltage three seconds c;ifter the load rejection test and does not use the term steady state. However, the Bases section clarifies that steady state conditions are established within three seconds, requiring this SR to be modified also. The Bases section will also be revised to reflect the 4000-volt motor maximum continuous voltage rating of 4400-volts.

3.0 TECHNICAL

EVALUATION As stated in WCAP-17308-NP, plant safety analyses make specific assumptions regarding emergency core cooling system (ECCS) flow to provide the core cooling Serial No.19-012 Docket Nos.: 50-338/339 Attachment 1 Page 6 of 12 function to mitigate an accident.

The analyses require minimum flow values which correspond to a minimum voltage. As stated in IEEE Std 666-1991, Table 5.3, induction motor slip increases at 90 percent rated voltage and decreases at 110 percent rated voltage. A decrease in motor slip results in higher motor speed and higher system flow. Therefore, the proposed change to reduce the TS SRs maximum voltage from 4580-volts to 4400-volts has no impact on the minimum analyzed ECCS flow, since it is based on minimum voltage (and frequency).

The impact of higher voltage (using 4400V) and speed has been evaluated to ensure existing analyses that consider maximum pump flow rates are not impacted.

The impact of over-voltage and frequency on maximum pump flow rates for systems that are relied on to mitigate accident conditions has previously been evaluated.

Since this evaluation was based on 110% of rated motor voltage, there are no impacts to the results. Section 3.1.2 of WCAP-17308-NP indicates that the net EOG loading is not impacted by voltage since induction motors are constant-power loads; motor current and voltage are inversely proportional and power * (voltage x current) is constant.

This relationship generally applies to induction motors utilized within their continuous ratings. Exceeding the maximum voltage rating, as the existing Surveillance Requirements permit, may impact this assumption making determination of EOG loading more difficult.

IEEE Std 666-1991, Section. 5.7.2 indicates that voltages higher than 110 percent of rated voltage may saturate the stator iron, thereby increasing the fundamental and harmonic

  • components of exciting current and losses by many times; this increased excitation loss will result in higher motor temperature.

The indeterminate increased current must also be accounted for in the EOG loading for continuous voltage above 4400-volts.

The NAPS EOG loading calculation assumes a maximum voltage of 4400-volts which is consistent with the proposed change to reduce the TS SRs. The high voltage primarily impacts non-motor loads at the 480-volt level that draw higher current at higher voltage, such as heaters, resulting in a higher kW load on the EOG. The NAPS EOG fuel storage supply meets the UFSAR capacity requirements based on operating the EOG at full load, 3000-kW. This bounds the EOG loading in all cases. NEMA Standards Publication ANSI C84.1-2016, "Electric Power Systems and Equipment

-Voltage Ratings (60 Hertz)," establishes nominal voltage ratings and operating tolerances for 60Hz electric power systems. In defining maximum system voltages, voltage transients and temporary overvoltage are excluded.

The recommendations in ANSI C84.1 provide a reasonable guide for the NAPS 4160-volt system operating voltage ranges.

  • Two maximum (upper) voltage limits are provided.

The Range-A upper voltage limit is 4370-volts, where ANSI-C84.1 states utilization equipment shall be designed and rated to give fully satisfactory performance throughout this range. The Range-B upper voltage limit is 4400-volts, where ANSI C84.1 acknowledges that higher voltage results from practical design and operating conditions on supply or user systems., or both. The preferred offsite power supply voltage is maintained by the Reserve Station Service Transformer automatic load tap changer. The nominal control voltage is 4315-volts Serial No.19-012 Docket Nos.: 50-338/339 Attachment 1 Page 7 of 12 measured at the Transfer Buses. Some small voltage drop will occur between the Transfer Buses and the Emergency Buses. Each 4160-volt Emergency Bus has an overvoltage alarm. The nominal alarm voltage setting is 72.7-volts which equates to 72.7 x 4200/120 (potential transformer ratio) x '13 = 4407-volts.

The associated annunciator response procedures direct Operations to lower voltage when the alarm occurs when the emergency bus is supplied by any source including the EOG. The same alarms and annunciator response procedures are initiated by 480-volt bus overvoltage alarms. Maintaining 480-volt system voltage relies, in part, on maintaining 4160-volt system voltages.

The NAPS plant computer point emergency 4160-volt bus high voltage limit is also 4400-volts.

These alarms are not utilized to verify the TS SRs, but demonstrate that established voltage limits to detect miss-operation of electrical system voltage controls are consistent with this change. As stated in WCAP-17308-NP, a properly operating EOG governor and voltage regulator will be able to control voltage around a nominal value within the manufacturer's specified tolerances.

The original NAPS purchase specification for the EOG sets states that the exciter-regulator shall be suitable for maintaining normal operating voltage within +/- 1 percent. During development of the EOG

  • loading calculation, several EOG Fast Start and Black-Out periodic tests were reviewed.

Based on several tests for each NAPS EOG from 2011 to 2015, the as-found voltage was never greater than 4236-volts.

Several more recent Periodic Tests have been reviewed with similar results, the maximum voltage was 4235-volts.

Therefore, lowering the maximum allowable voltage from 4580-volts to 4400-volts is within the capabilities of the emergency diesel generator voltage regulator.

NEMA standard MG 1, "Motors and Generators," is frequently cited for motor design. NEMA MG 1, Section 12.44.*1 requires ac motors to operate at plus or minus 10 percent of rated voltage. The original purchase specifications for motors used at NAPS were reviewed and the motor maximum voltage limits were not quantified

  • in the specifications.

In recent years, one original motor purchase specification has been revised in order to purchase spare/replacement motors and the new revision specifies a maximum motor voltage requirement of 4400-volts.

There is no indication that any motors have been purchased with enhanced higher voltage ratings, (i.e., greater than 4000-volts plus 10 percent or 4400-volts).

4.0 REGULATORY EVALUATION

Dominion Energy Virginia proposes amendments to the EOG maximum voltage surveillance requirements in several North Anna Units 1 and 2 Technical Specification 3.8.1 ."AC Sources -Operating," sections from 4580-volts to 4400-volts.

The proposed surveillance requirement change would address the non-conservative maximum voltage acceptance criterion for EOG steady-state operation, which was identified during review of WCAP-17308-NP and the associated NRC Final Safety Evaluation.

The proposed surveillance requirement change ensures proper Surveillance Testing acceptance criteria for the standby EDGs that will ensure their Serial No.19-012 Docket Nos.: 50-338/339 Attachment 1 Page 8 of 12 capability to mitigate design basis accidents and transients and to maintain the units in a safe shutdown condition.

The proposed change will ensure that the TS3.8.1 Surveillance Tests verify that EOG performance is within the voltage limits currently used in both electrical system and mechanical system analyses.

The proposed 4400-volt limit is consistent with normal station operation and within the capabilities of the EOG voltage regulators.

4. 1 Applicable Regulatory Requirements/Criteria The NRC Final Safety Evaluation for WCAP-17308-NP describes applicable regulatory guidance for the EOG voltage and frequency SRs. The focus below is on requirements/criteria associated with the EDGs. Proper operation of the electrical systems ensures operation of many other systems. Changes described in this LAR are consistent with the following regulations and continue to meet the intent of the applicable General Design Criteria.

GDC 17 -Electric Power Systems 10 CFR 50, Appendix A, General Design Criterion (GDC) 17, ensures an onsite electric power system is provided to permit functioning of structures, systems, and components important to safety. As required by GDC 17, the design of the alternating current electrical power system provides independence and redundancy to ensure an available source of power to the engineered safety features systems. The 4400-volt SR helps to ensure that the onsite EDGs are capable of performing their functions.

GDC 18 -Inspection and Testing of Electric Power Systems . 10 CFR 50, Appendix A, General Design Criterion (GDC) 18 requires electric power systems important to safety to be designed to permit appropriate periodic inspection and testing of important areas and features, such as wiring, insulation, connections, and switchboards, to assess the continuity of the systems and the condition of their components.

GDC 18 requires the systems shall be designed with a capability to test periodically (1) the operability and functional performance of the components of the systems, such as onsite power sources, relays, switches, and buses, and (2) the operability of the systems, as a whole and under conditions as close to design as practical, the full operation sequence that brings the systems into operation, including operation of applicable portions of the protection system, and the transfer of power between the nuclear power unit, the offsite power system, and the onsite power system. The automatic start and loading capability of the Emergency Generator (EG) System is tested periodically by simulating a loss of voltage on the associated bus in conjunction with a safety injection test signal. This assures operability of the EG System in the event of a limiting event or a loss of offsite power. Individual components, controls, and automatic protective devices for the EG System and its subsystems are tested and inspected on a periodic basis in accordance with the manufacturer's recommendations.

To further demonstrate operability, the EDGs are periodically started, accelerated to Serial No.19-012 Docket Nos.: 50-338/339 Attachment 1 Page9of12 rated speed, loaded, and subjected to load rejection.

A maximum steady-state voltage of 4400-volts is appropriate for surveillance testing. Regulatory Guide 1.9, Selection, Design, Qualification, and Testing of Emergency Diesel Generator Units Used as Class 1 E Onsite Electric Power Systems at Nuclear Power Plants When the NRC introduced Regulatory Guides (RG) to replace Safety Guides (SG), SG 9, dated March 10, 1971, was referenced as RG 1.9, with an issue date of March 10, 1971. Since the North Anna SER requires that EDGs meet the requirements of HG 1.9, the intent of the SER review was that the EDGs meet the requirements of SG 9. Safety Guide 9, "Selection of Diesel Generator Set Capacity for Standby Power Supplies," provides guidance in the selection, design, and qualification of safety-related diesel generator units, such that they be selected with sufficient capacity, be qualified and be maintained for reliability equal to or above the levels selected for a limiting event. Each EDG meets the requirement of SG 9 for having a continuous load rating equal to or greater than the sum of the loads needed to be powered at any one time. The ability of each EDG to meet this requirement, as well as the limits imposed on voltage, frequency, and speed, are demonstrated periodically utilizing the TS SRs. 4.2 No Significant Hazards Consideration In accordance with the criteria set forth in 10 CFR 50.92, Dominion Energy Virginia has performed an analysis of the proposed amendment and concluded that it does not represent a significant hazards consideration.

The following discussion is provided in support of this conclusion:

i. ii. Does the proposed change involve a significant increase in the probability or consequences of an accident previously evaluated?

Response:

No Modifying the maximum steady-state voltage requirement does not increase the probability of an accident.

Verifying proper operation of the EDGs to maintain adequate voltage ensures proper electrical and mechanical system function and does not increase the consequences of an accident.

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

Response:

No The proposed change would provide more restrictive acceptance criteria to be applied to existing technical specification surveillance tests that demonstrate the capability of the facility EDGs to perform their design function.

The proposed acceptance criteria changes would not create any new failure mechanisms, malfunctions, or accident initiators not considered in the design and licensing iii. Serial No.19-012 Docket Nos.: 50-338/339 Attachment 1 Page 10 of 12 bases. Therefore, the possibility of a new or different kind of accident from any previously evaluated has not been created. Does the proposed change involve a significant reduction in margin of safety? Response:

No The proposed change involves decreasing maximum voltage test acceptance criterion for EOG Surveillance Tests. The conduct of surveillance tests on related plant equipment is a means of assuring that the equipment is capable of maintaining the margin of safety established in the safety analyses for the facility.

The proposed amendment does not affect EOG performance as described in the design basis analyses, including the capability of the EOG to maintain required voltage for proper operation of plant safety loads. The proposed amendment does not introduce changes to limits established in the accident analyses.

Therefore, the proposed amendment does not involve a significant reduction in a margin of safety. Based on the discussion above, Dominion Energy Virginia concludes that the proposed TS change presents no significant hazards consideration under the standards set forth in 10 CFR 50.92(c), and, accordingly, a determination of "no significant hazards consideration" is justified.

5.0 PRECEDENTS

This proposed amendment was initiated based on a review of WCAP-17308-NP, Revision O and the associated NRC Final Safety Evaluation.

Both recognize the potential for stations to revise their Technical Specification SRs to complement their analyses, or alternatively to revise the analyses to complement their SRs. The NRC has approved the following requests to resolve a non-conservative Technical Specification related to SRs for EOG steady-state frequency and/or voltage:

  • On February 12, 2018_, the NRC issued Amendment Nos. 341 and 334, Docket Nos. 50-327 and 50-328, to Sequoyah Nuclear Plant, Units 1 and 2, respectively.

The amendments correct a non-conservative Technical Specification Surveillance Requirement acceptance criterion for the diesel generator state frequency in Limiting Condition for Operation 3.8.1, "AC Sources -Operating."

6.0 ENVIRONMENTAL

CONSll;)ERATION Serial No.19-012 Docket Nos.: 50-338/339 Attachment 1 Page 11 of 12 The proposed amendment meets the eligibility criterion for categorical exclusion set forth in 1 O CFR 51.22(c)(9) as follows: i. The proposed change inyolves no significant hazards consideration.

As described in Sectiqn 4.2 above, the proposed change involves no significant hazards consiqeration.

ii. There are no significant changes in the types or significant increase in the amounts of any effluents that may be released off-site.

The proposed change implements a change to TS SRs for maximum EOG voltage and, as such, does not involve the installation of any new equipment or the modification of any equipment that may affect the types or amounts of effluents that may be released off-site.

The proposed change will have no impact on normal plant releases and will not increase the predicted radiological consequences of accidents postulated in the UFSAR. There are no significant changes in the types or significant increase in the amounts of any effluents that may b~ released off-site.

iii. There is no significant in9rease in individual or cumulative occupational radiation exposure.

The proposed change implements a change to TS SRs for the maximum EOG voltage. The proposed TS change does not implement plant physical changes or result in plant operation in a configuration outside the plant safety analyses or design bases. Therefore, there is no significant increase in individual or cumulative occupational radiation exposure associated with the proposed change. Based on the above, Dominion Energy Virginia concludes that, pursuant to 1 O CFR 51.22(b), no environmental impact statement or environmental assessment need be prepared in connection with the proposed amendment.

7.0 CONCLUSION

S The prpposed change reduces the maximum voltage specified for TS Section 3.8.1 Surveillance Requirements associc;tted with the Emergency Diesel Generators (EDGs). The proposed change addresses concerns identified by WCAP-17308-NP regarding the maximum steady-state equipment voltage rating. A technical evaluation of the proposed change concludes that the propqsed reduction in maximum allowable steady-state voltage in the TS 3.8.1 SRs:

  • is consistent with ECCS flovv calculations
  • is consistent with EOG electrical loading calculations
  • is consistent with EOG fuel qonsumption calculations Serial No.19-012 Docket Nos.: 50-338/339 Attachment 1 Page 12 of 12
  • is within the EOG governor and voltage regulator capabilities
  • provides rated voltage to electrical loads The conduct of surveillance tests on safety-related plant equipment is a means of assuring that the equipment is capable of performing its safety function as designed.

Therefore, Dominion Energy Virginia concludes, based on the considerations discussed herein, that (1) there is reasonable assurance that the health and safety of the public will not be endangered by operation in the proposed manner, (2) 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.

8.0 REFERENCES

8.1. North

Anna UFSAR Chapter 8, Electric Power Systems 8.2. Westinghouse WCAP-17308-NP, Revision 0, dated April 2012, "Treatment of Diesel Generator (DG) Technical Specification Frequency and Voltage Tolerances" 8.3. NRC Administrative Letter 98-10, "Dispositioning of Technical Specifications that are Insufficient to Assure Plant Safety," December 29, 1998 8.4. Final Safety Evaluation by the Office of Nuclear Reactor Regulation, WCAP-17308-NP, Revision 0, "Treatment of Diesel Generator (DG) Technical Specification Frequency and Voltage Tolerances," Pressurized Water Reactor Owners Group Project No. 694 8.5. Regulatory Guide 1.9, "Selection, Design, Qualification, and Testing of Emergency Diesel Generator Units Used as Class 1 E Onsite Electric Power Systems at Nuclear Power Plants" 8.6. IEEE Std 666-1991, "IEEE Design Guide for Electric Power Service Systems for Generating Stations"

-Voltage Ratings (60 Hertz)" 8.8. North Anna Unit 1 Setpoint Document Attachment 2 Serial No.19-012 Docket Nos.: 50-338/339 MARKED-UP TECHNICAL SPECIFICATIONS PAGES VIRGINIA ELECTRIC AND POWER COMPANY (DOMINION ENERGY VIRGINIA)

NORTH ANNA POWER STATION UNITS 1 AND 2

-NUCLEAR DESIGN INFORMATION PORTAL -SURVEILLANCE REQUIREMENTS SR 3.8.1.1 SR 3.8.1.2 SURVEILLANCE Verify correct breaker alignment and indicated power availability for each required offsite circuit. -------------------NOTES---------------

1. All EOG starts may be preceded by an engine prelube period and followed by a warmup period prior to loading! 2. A modified EOG start involving idling and gradual acceleration to synchronous speed may be used for this SR as recommended by the manufacturer.

When modified start procedures are not used, the time, voltage, and frequency tolerances of SR 3.8.1.7 must be met. Verify each required EOG starts from standby conditions and achieves steady state voltage 3740 V and :5 4580 V, and frequency 59. 5 Hz and :5 60. 5 Hz *!4400 V ! North Anna Units 1 and 2 3.8.1-8 AC Sources-Operating

3.8.1 FREQUENCY

In accordance with the Surveillance Frequency Control Program In accordance with the Surveillance Frequency Control Program Amendments 262/243

-NUCLEAR DESIGN INFORMATION PORTAL -SURVEILLANCE REQUIREMENTS SURVEILLANCE SR 3.8.1.7

  • All EOG starts may be preceded by an engine prelube period. Verify each required EOG starts from standby condition and achieves a. In S 10 seconds, voltage~ 3960 V and frequency~

59~5 Hz; and b. Steady state voltage~ 3740 V and 1-4-40_0_V~IS 4580 V, and frequency~

59.5 Hz and ---S 60.5 Hz. SR 3.8.1.8 -------------------NOTE--------------

This Surveillance shall not normally be performed in MODE 1 or 2. However, this Surveillance may be performed to reestablish OPERABILITY provided an assessment determines the safety of the unit is maintained or enhanced.

  • Verify manual transfer of AC power sources from the normal offsite circuit to the alternate required offsite circuit. North Anna Units 1 and 2 3.8.1-10 AC Sources-Operating

3.8.1 FREQUENCY

In accordance with the Surveillance Frequency Control Program In accordance with the Surveillance Frequency Control Program Amendments 262/260

-NUCLEAR DESIGN INFORMATION PORTAL-SURVEILLANCE REQUIREMENTS SR 3.8.1.9 SURVEILLANCE

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

Jf performed with EOG synchronized with offsite power, it shall be performed at a power factor~ 0.9. However, if grid conditions do not permit, the power factor limit is not required to be met. Under this condition, the power factor shall be maintained as close to the limit as practicable.

Verify each required EOG rejects a load greater than or equal to its associated single largest post-accident load, and: a. Following load rejection, the frequency is~ 66 Hz; b. Within 3 seconds following load .------*__,rejection, the voltage is~ 3740 V and !4400 V I~ 4580 'J; and c. Within 3 seconds following load rejection, the frequency is~ 59.5 Hz and~ 60.5 Hz. North Anna Units 1 and 2 3.8.1-11 AC Sources-Operating

3.8.1 FREQUENCY

In accordance with the Surveillance Frequency Control Program Amendments 262/243

-NUCLEAR DESIGN INFORMATION PORTAL-SURVEILLANCE REQUIREMENTS SURVEILLANCE SR 3.8.1.10 -------------------NOTES---------------

1. All EOG starts may be preceded by an engine prelube period. 2. This Surveillance shall not normally be performed in MODE 1, 2, 3, or 4. However, portions of the Surveillance may be performed to reestablish OPERABILITY provided an assessment determines the safety of the unit is maintained or enhanced.

Verify on an actual or simulated loss of offsite power signal: a. De-energization of emergency buses; b. Load shedding from emergency buses; c. Each required EOG auto-starts from standby condition and: 1. energizes pe_rmanently connected loads in~ 10 seconds, 2. energizes auto-connected shutdown loads through sequencing timing relays, 3. maintains steady state voltage 3740 V and 4-58e-V, j4400 V 4. maintains steady state frequency 59.5 Hz and~ 60.5 Hz, and 5. supplies permanently connected and auto-connected shutdown loads for 5 minutes. North Anna Units 1 and 2 -3.8.1-12 AC Sources-Operating

3.8.1 FREQUENCY

In accordance with the Surveillance Frequency Control Program Amendments 262/243

-NUCLEAR DESIGN INFORMATION PORTAL-SURVEILLANCE REQUIREMENTS SURVEILLANCE SR 3.8.1.11 -------------------NOTES---------------

1. All EOG starts may be preceded by pre,l ube period. 2. This Surveillance shall not normally be performed in MODE 1 or 2. However, portions of the Surveillance may be performed to reestablish OPERABILITY provided an assessment determines the safety of the unit is maintained or enhanced.

Verify on an actual or simulated Engineered Safety Feature (ESF) actuation signal each LCO 3.8.1.b EOG auto-starts from standby condition and: a. Ins 10 seconds after auto-start and during tests, achieves voltage 3960 V and frequency~

59.5 Hz; b. Achieves steady state voltage~ 3740 V 4-00~V~-land S 4580 V and frequency~

59.5 Hz -* ~~~--and S 60.5 Hz; c. Operates for~ 5 minutes; *d. Permanently connected loads remain energized from the offsite power system; and e. Emergency loads are energized or auto-connected through the sequencing timing relays from the offsite power system. North Anna Units 1 and 2 3.8.1-13 AC Sources-Operating

3.8.1 FREQUENCY

In accordance with the Surveillance Frequency Control Program Amendments 262/243

-NUCLEAR DESIGN INFORMATION PORTAL -SURVEILLANCE REQUIREMENTS SURVEILLANCE SR 3.8.1.14 -------------------NOTES------------------

1. This Surveillance shall be performed within 5 minutes of shutting down the EOG after the EOG has operated 2 hours2.314815e-5 days <br />5.555556e-4 hours <br />3.306878e-6 weeks <br />7.61e-7 months <br /> loaded~ 2500 kW and s 2600 kW or after operating temperatures have stabilized.

Momentary transients outside of load range do not invalidate this test. 2. All EOG starts may be preceded by an engine prelube period.

  • Verify each required EOG starts and achieves a. In S 10 seconds, voltage~ 3960 V and frequency~

59~5 Hz; and b. Steady state voltage~ 3740 V, and 4-00_V_!s 4580 V and frequency~

59.5 Hz and ..__ _ ___.s 60. 5 Hz. SR 3.8.1.15 -----------------

This Surveillance shall not normally be performed in MODE 1, 2, 3, or 4. However, this Surveillance may be performed to reestablish OPERABILITY provided an assessment determines the safety of the unit is maintained or enhanced.

Verify each required EOG: a. Synchronizes with offsite power source while loaded with emergency loads upon a simulated restoration of offsite power; b. Transfers loads to offsite power source; and c. Returns to ready-to-load operation.

North Anna Units 1 and 2 3.8.1-16 AC Sources-Operating

3.8.1 FREQUENCY

In accordance with the Surveillance Frequency Control Program In accordance with the Surveillance Frequency Control Program Amendments

~2/243

-NUCLEAR DESIGN INFORMATION PORTAL-SURVEILLANCE REQUIREMENTS SURVEILLANCE SR 3.8.1.17 ------------------NOTES-------------------

1. All EOG starts may be preceded by an engine prelube period. 2. This Surveillance shall not normally be performed in MODE 1, 2, 3, or 4: However, portions of the Surveillance may be performed to reestablish OPERABILITY provided an assessment determines the safety of the unit is maintained or enhanced.

Verify on an actual or simulated loss of offsite power signal in conjunction with an actual or simulated ESF actuation signal: a. De-energization of emergency buses; b. Load shedding from emergency buses; and c. Each LCO 3.8.1.b EOG auto-starts from standby condition and: 1. energizes permanently connected loads in~ 10 seconds, 2. energizes auto-connected emergency loads through load sequencing timing relays, 3. achieves steady state voltage 3740 V and 4580 V, !4400 V, 4. achieves steady state frequency 59.5 Hz and~ 60.5 Hz, and 5. supplies permanently connected and auto-connected emergency loads for 5 minutes. North Anna Units 1 and 2 3.8.1-18 AC Sources-Operating

3.8.1 FREQUENCY

In accordance with the Surveillance Frequency Control Program Amendments

~2/243

-NUCLEAR DESIGN INFORMATION PORTAL -SURVEILLANCE REQUIREMENTS SURVEILLANCE SR 3.8.1.18 All EOG starts may be preceded by an engine prelube period. Verify when started simultaneously from standby condition, each LCO 3.8.l.b EOG achieves:

a. in~ 10 seconds, voltage~ 3960 V and frequency~

59.5 Hz; and b. steady state voltage~ 3740 V and ..... !4_4_00--V,---,!~

4580 V, and frequency~

59.5 Hz and .__ __ ..... 60. 5 Hz. North Anna Units 1 and 2 3.8.1-19 AC Sources-Operating

3.8.1 FREQUENCY

In accordance with the Surveillance Frequency Cont ro 1 Program Amendments 262/243 Attachment 3 Serial No.19-012 Docket Nos.: 50-338/339 PROPOSED TECHNICAL SPECIFICATIONS PAGES VIRGINIA ELECTRIC AND POWER COMPANY (DOMINION ENERGY VIRGINIA)

NORTH ANNA POWER STATION UNITS 1 AND 2 SURVEILLANCE REQUIREMENTS SR 3.8.1.1 SR 3.8.1.2 SURVEILLANCE Verify correct breaker alignment and indicated power availability for each required offsite circuit. ---------------

---NOTES---------------

1. All EOG starts may be preceded by an engine prelube period and followed by a warmup period prior to loading. 2. A modified EOG start involving idling and gradual acceleration to synchronous speed may be uied for this SR as recommended by the manufacturer.

When modified start procedures are not used, the time, voltage, and frequency tolerances of SR 3.8.1.7 must be met. Verify each required EOG starts from standby conditions and achieves steady state voltage~ 3740 V and~ 4400 V, and frequency~

59.5 Hz and~ 60.5 Hz. North Anna Units 1 and 2 3.8.1-8 AC Sources-Operating

3.8.1 FREQUENCY

In accordance with the Surveillance Frequency Control Program In accordance with the Surveillance Frequency Control Program Amendments SURVEILLANCE REQUIREMENTS SR 3.8.1.7 SR 3.8.1.8 SURVEILLANCE

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

All EOG starts may be preceded by an engine prelube period. Verify each required EOG starts from standby condition and achieves a. In S 10 seconds, voltage~ 3960 V and frequency~

59.5 Hz; and b. Steady state voltage~ 3740 V and S 4400 V, and frequency~

59.5 Hz and S 60.5 Hz. . -------------------NOTE--------------

This Surveillance shall not normally be performed in MODE 1 or 2. However, this Surveillance may be performed to reestablish OPERABILITY provided an assessment determines the safety of the unit is maintained or enhanced.

Verify manual transfer of AC power sources from the normal offsite circuit to the alternate required offsite circuit. North Anna Units 1 and 2 3.8.1-10 AC Sources-Operating

3.8.1 FREQUENCY

In accordance with the Surveillance Frequency Control Program In accordance with the Surveillance Frequency Control Program Amendments SURVEILLANCE REQUIREMENTS SR 3.8.1.9 SURVEILLANCE

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

If performed with EOG synchronized with offsite power, it shall be performed at a power factor~ 0.9. However, if grid conditions do not permit, the power factor limit is not required to be met. Under this condition, the power factor shall be maintained as close to the limit as practicable.

Verify each required EOG rejects a load greater than or equal to its associated single largest post-accident load, and: a. Following load rejection, the frequency is~ 66 Hz; b. Within 3 seconds following load rejection, the voltage is~ 3740 V and 4400V; and c. Within 3 seconds following load rejection, the frequency is~ 59.5 Hz and~ 60.5 Hz. North Anna Units 1 and 2 3.8.1-11 AC Sources-Operating

3.8.1 FREQUENCY

In accordance with the Surveillance Frequency Control Program Amendments SURVEILLANCE REQUIREMENTS SURVEILLANCE SR 3.8.1.10 -------------------NOTES---------------

1. All EOG starts may be preceded by an engine prelube period. 2. This Surveillance shall not normally be performed in MODE 1, 2, 3, or 4. However, portions of the Surveillance may be performed to reestablish OPERABILITY provided an assessment determines the safety of the unit is maintained or enhanced~

Verify on an actual or simulated loss of offsite power signal: a. De-energization of emergency buses; b. Load shedding from emergency buses; c. Each required EOG auto-starts from standby condition and: 1. energizes permanently connected loads in~ 10 seconds, 2. energizes auto-connected shutdown loads through sequencing timing relays, 3. maintains steady state voltage 3740 V and~ 4400 V, 4. maintains steady state frequency 59.5 Hz and~ 60.5 Hz, and 5. supplies permanently connected and auto-connected shutdown loads for 5 minutes. North Anna Units 1 and 2 3.8.1-12 AC Sources-Operating

3.8.1 FREQUENCY

In accordance with the Surveillance Frequency Control Program Amendments SURVEILLANCE REQUIREMENTS SURVEILLANCE SR 3.8.1.11 -------------------NOTES---------------

1. All EOG starts may be preceded by prelube period. 2. This Surveillance shall not normally be performed in MODE 1 or 2 .. However, portions of the Surveillance may be performed to reestablish OPERABILITY provided an assessment determines the safety of the unit is maintained or enhanced.

Verify on an actual or simulated Engineered Safety Feature (ESF) actuation signal each LCO 3.8.1.b EOG auto-starts from standby condition and: a. In~ 10 seconds after auto-start and during tests, achieves voltage 3960 V and frequency~

59.5 Hz; b. Achieves steady state voltage~ 3740 V and~ 4400 V and frequency~

59.5 Hz and~ 60.5 Hz; c. Operates for~ 5 minutes; ct. Permanently connected loads remain energized from the offsite power system; and e. Emergency loads are energized or auto-connected through the sequencing timing relays from the offsite power system. North Anna Units 1 and 2 3.8.1-13 AC Sources-Operating

3.8.1 FREQUENCY

In accordance with the Surveillance Frequency Control Program Amendments SURVEILLANCE REQUIREMENTS SURVEILLANCE SR 3.8.1.14 -------------------NOTES------------------

1. This Surveillance shall be performed within 5 minutes of shutting down the EOG after the EOG has operated 2 hours2.314815e-5 days <br />5.555556e-4 hours <br />3.306878e-6 weeks <br />7.61e-7 months <br /> loaded~ 2500 kW and 2600 kW or after operating temperatures have stabilized.

Momentary transients outside of load range do not invalidate this test. 2. All EOG starts may be preceded by an engine prelube period. Verify each required EOG starts and achieves a. In~ 10 seconds, voltage~ 3960 V and frequency~

59.5 Hz; and b. Steady state voltage~ 3740 V, and 4400 V and frequency~

59.5 Hz and 60.5 Hz. SR 3.8.1.15 This Surveillance shall not normally be performed in MODE 1, 2, 3, or 4. However, this Surveillance may be performed to reestablish OPERABILITY provided an assessment determines the safety of the unit is maintained or enhanced.

Verify each required EOG: a. Synchronizes with offsite power source while loaded with emergency loads upon a simulated restoration of offsite power; b. Transfers loads to offsite power source; and c. Returns to ready-to-load operation.

North Anna Units 1 and 2 3.8.1-16 AC Sources-Operating

3.8.1 FREQUENCY

In accordance with the Surveillance Frequency Control Program In accordance with the Surveillance Frequency Contra 1 Program Amendments SURVEILLANCE REQUIREMENTS . SURVEILLANCE SR 3.8.1.17 ------------------NOTES-------------------

1. All EOG starts may be preceded by an engine prelube period. 2. This Surveillance shall not normally be performed in MODE 1, 2, 3, or 4. However, portions of the Surveillance may be performed to reestablish OPERABILITY provided an assessment determines the safety of the unit is maintained or enhanced.

Verify on an actual or simulated loss of offsite power signal in conjunction with an actual or simulated ESF actuation signal: a. De-energization of emergency buses; b. Load shedding from emergency buses; and c. Each LCO 3.8.1.b EOG auto-starts from standby condition and: 1. energizes permanently connected loads in~ 10 seconds, 2. energizes auto-connected emergency loads through load sequencing timing relays, 3. achieves steady state voltage 3740 V and~ 4400 V, 4. achieves steady state frequency 59.5 Hz and~ 60.5 Hz, and 5. supplies permanently connected and auto-connected emergency loads for 5 minutes. North Anna Units 1 and 2 3.8.1-18 AC Sources-Operating

3.8.1 FREQUENCY

. In accordance with the Surveillance Frequency Control Program Amendments SURVEILLANCE REQUIREMENTS SURVEILLANCE SR 3.8.1.18 -------------------NOTE-------------------

All EOG starts may be preceded by an engine prelube period. Verify when started simultaneously from standby condition, each LCO 3.8.1.b EOG achieves:

a. in~ 10 seconds, voltage~ 3960 V and frequency~

59.5 Hz; and b. steady state voltage~ 3740 V and 4400 V, and frequency~

59.5 Hz and 60.5 Hz. North Anna Units 1 and 2 3.8.1-19 AC Sources-Operating

3.8.1 FREQUENCY

In accordance with the Surveillance Frequency Control Program Amendments Attachment 4 Serial No.19-012 Docket Nos.: 50-338/339 MARKED-UP AND PROPOSED TECHNICAL SPECIFICATIONS BASES PAGES (for information only) VIRGINIA ELECTRIC AND POWER COMPANY (DOMINION ENERGY VIRGINIA)

NORTH ANNA POWER STATION UNITS 1 AND 2 BASES ACTIONS (continued)

SURVEILLANCE REQUIREMENTS 4400V -NUCLEAR DESIGN INFORMATION PORTAL-M.1 AC Sources-Operating B 3.8.1 Condition M corresponds to a level of degradation in which all redundancy in the AC electrical power supplies has been lost. At this severely degraded level, any further losses in the AC electrical power system will cause a loss of function.

Therefore, no additional time is justified for continued operation.

The unit is required by LCO 3.0.3 to commence a controlled shutdown.

The AC sources are designed to permit inspection and testing of all important areas and features, especially those that have a standby function, in accordance with GDC 18 (Ref. 1). Periodic component tests are supplemented by extensive functional tests during refueling outages (under simulated accident conditions).

The SRs for demonstrating the OPERABILITY of the EDGs are in accordance with the recommendations of Safety Guide 9 (Ref. 3), Regulatory Guide 1.108 (Ref. 8)(subsequently replaced by Regulatory Guide 1.9 (Ref. 13)), and Regulatory Guide 1.137 (Ref. 9), as addressed in the UFSAR. Where the SRs discussed herein specify voltage and frequency tolerances, the following is applicable.

The minimum steady state output voltage of 3740 Vis 90% of the nominal 4160 V output voltage. This value, which is specified in ANSI C84.1 (Ref. 10), allows for voltage drop to the terminals of 4000 V motors whose minimum operating voltage is specified as 90% or 3600 V. It also allows for voltage drops to motors and other equipment down through the 120 V level where minimum operating voltage is also usually specified as 90% of name plate rating. The specified maximum steady state out ut volta e 4680 Vis equal to the maximum operating voltage specifi ct for 4000 V motors. It ensures that for a lightly loaded distribution system, the voltage at the terminals of 4000 V motors is no more than the maximum rated operating voltages.

The specified minimum and maximum frequencies of the EOG are 59.5 Hz and 60.5 Hz, respectively.

These values are< +/-1% of the 60 Hz nominal frequency and are derived from the safety analysis assumptioris for operation of ECCS pump criteria.

North Anna Units 1 and 2 B 3.8.1-21 Revision .§.J.

't BASES ACTIONS (continued)

SURVEILLANCE REQUIREMENTS M.1 AC Sources-Operating B 3.8.1 Condition M corresponds to a level of degradation in which all redundancy in the AC-electrical power supplies has been lost. At this severely degraded level, any further losses in the AC electrical power system will cause a loss of function.

Therefore,*

no additional time is justified for continued operation.

The unit is required by LCD 3.0.3 to commence a controlled shutdown.

The AC sources are designed to permit inspection and testing of all important areas and features, especially those that have*a standby function, in accordance with GDC 18 (Ref. 1). Periodic component tests are supplemented by extensive functional tests during refueling outages (under simulated accident conditions).

The SRs for demonstrating the OPERABILITY of the EDGs are in accordance with the recommendations of Safety Guide 9 (Ref. 3), Regulatory Guide 1.108 (Ref. 8)(subsequently replaced by Regulatory Guide 1.9 (Ref. 13)), and Regulatory Guide 1.137 (Ref. 9), as addressed in the UFSAR. Where the SRs discussed herein specify voltage and frequency tolerances, the following is applicable.

The minimum steady state output voltage of 3740 Vis 90% of the nominal 4160 V output voltage. This value, which is specified in ANSI C84.l (Ref. 10), allows for voltage drop to the terminals of 4000 V motors whose minimum operating voltage is specified as 90% or 3600 V. It also allows for voltage drops to motors and other equipment down through the 120 V level where minimum operating voltage is also usually specified as 90% of name plate rating. The specified maximum steady state output voltage of 4400 Vis equal to the maximum operating voltage specified for 4000 V motors. It ensures that for a lightly loaded distribution system, the voltage at the terminals of 4000 V motors is no more than the maximum rated operating voltages.

The specified minimum and maximum frequencies of the EOG are 59.5 Hz and 60.5 Hz, respectively.

These values are< +/-1% of the 60 Hz nominal frequency and are derived from the safety analysis assumptions for operation of ECCS pump criteria.

North Anna Units 1 and 2 B 3.8.1-21 Revision

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