ML19290E079

Auxiliary Power Sys Voltage Study

ML19290E079
Person / Time
Site:	Maine Yankee
Issue date:	02/29/1980
From:	Johnson P, Urbanowski S Maine Yankee
To:
Shared Package
ML19290E078	List: ML19290E077 ML19290E079
References
YAEC-1204, NUDOCS 8003040197
Download: ML19290E079 (38)

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o AUXILIARY POWER SYSTEM VOLTAGE STUDY FOR MAINE YANKEE ATOMIC POWER STATION By P. R. Johnson and S. F. Urbanowski A

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Prepared By:

o L-P. R. Johnson, Electrical Engineer Date d[o?d/dC Prepared By:

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F. Urbanowski, Senior Engineer Date 2-8 !b Reviewed By:

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G. (souderos, Senior Electrical Engineer Dale Approved By:

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N-F. D. Baxter, Manager Date Electrical Engineering Group Yankee Atomic Electric Company Nuclear Services Division 25 Research Drive Westboro, Massachusetts 01581 e

DISCLAIMER OF RESPONSIBILITY This document was prepared by Yankee Atomic Electric Company on behalf of Maine Yankee Atomic Power Corporation.

This document is believed to be completely true and accurate to the best of our knowledge and information.

It is authorized for use specifically by Yankee Atomic Electric Company, Maine Yankee Atomic Power Corporation and/or the appropriate subdivisions within the Nuclear Regulatory Commission only.

With regard to any unauthorized use whatsoever, Yankee Atomic Electric Company, Maine Yankee Atomic Power Corporation and their officers, directors, agents and employees assume no liability nor make any warranty or representation with respect to the contents of this document or to its accuracy or completeness.

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W ABSTRACT This report presents the results of an exhaustive review of the auxiliary power system at the Maine Yankee Atomic Power Station which was initiated by a directive from the Nuclear Regulatory Commission. This report demonstrates that the Maine Yankee Atomic Power Station offsite and auxiliary power systems are of sufficient capacity to automatically start and operate all safety loads, assuming that all onsite power systems are not available.

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ACKNOWLEDGEMENTS The authors wholeheartedly thank Jin DiLuca (Northeastern University Co-op student) for his significant role in the preparation of this report.

Jim assisted in nearly every phase of the p"oject including data preparation, modeling and performing the various load flow studies on the interactive computer.

We also wish to that.k the staff of the Rhode Island, Eastern Massachusetts, and Vermont Energy Control (REMVEC); especially Dave Hayward, Paul Harnett, and Russ Burke for their assistance and the use of their facilities.

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TABLE OF CONTENTS Page DISCLAIMER OF RESF0NSIBILITY..............................

11 ABSTRACT..................................................

iii A C KN0WL E DG E ME N T S..........................................

iv TABLE OF C0NTENTS.........................................

V LIST OF FIGURES...........................................

Vi LIST OF TABLES............................................

vii

1.0 INTRODUCTION

I 2.0 AUXILIARY POWER SYSTEM....................................

2 2.1 Description...........................................

2 2.2 Voltage Requirements..................................

2 2.2.1 Offsite Power System Operating Voltagt Range..................................

8 2.2.2 Motors and Contactors..........................

8 2.2.3 Undersoltage Relay Setpoints...................

9 3.0 ANALYSIS..................................................

11 3.1 Problem Statement.....................................

11 3.2 Method................................................

12 3.3 Assumptions...........................................

13 3.3.1 Impedance Mode 1................................

13 3.3.2 Maximum Load Mode 1.............................

15 3.3.3 Minimum Load Model.............................

16

4.0 CONCLUSION

S...............................................

21 5.0 VERIFICATION..............................................

27 REFERENCES................................................

29

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LIST OF FIGURES Number Title Page 2.1 One Line Diagram Auxiliary Power System Maine Yankee Atomic Power Company......................

3 2.2 One Line Diagram 6900 Volt Buses 1 & 2 Maine Yankee Atomic Power Company......................

4 2.3 One Line Diagram 4160 Volt Buses 3 & 5 thine Yankee Atomic Powe r Company......................

5 2.4 One Line Diagraa 4160 Volt Buses 4 6 6 Maine Yankee Atomic Power Company......................

6 2.5 One Line Diagram 480 Volt Buses 7.6 8 Maine Yankee Atomic Power Company......................

7 3.1 Load Flow Model Maine Yankee Atomic Power Company......................

14 9

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LIST OF TABLES Number Title Page 2.1 Auxiliary Power System Voltage Requirements............

9 3.1 Loading Assumptions - Case 1...........................

17 3.2 Loading Assumptions - Case 2...........................

18 3.3 Loading Assumptions - Case 3...........................

19 3.4 Loading Assumptions - Case 4...........................

20 4.1 Bus and Equipment Terminal Voltages - Case 1...........

23 4.2 Bus and Equipment Te rminal Voltages - Case 2...........

24 4.3 Bus and Equipment Te rminal Voltages - Case 3...........

25 4.4 Bus and Equipment Te rminal Voltages - Case 4...........

26 5.1 Predicted Voltage Vs. Measured Voltage.................

28

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1.0 INTRODUCTION

Criterion 17 of 10CFR50 Appendix A, " General Design Criteria for Nuclear Power Plants" states in part that:

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

The safety function of each system (assuming the other system is not functioning) shall be to provide sufficient capacity and carability 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 maintained in the event of postulated accidents."

An incident at Arkansas Nuclear One has brought into question the conformance of that station to Criterion 17 regarding the station electric distribution system design. Consequently the NRC has required all power reactor licensees to review their electric power systems and determine if the offsite power system and the onsite distribution system are of sufficient capacity to automatically start and operate all safety loads, assuming that all onsite ac power sources are not available.

(This directive to all power reactor licensees is included as Reference (a)).

This report presents the results of our review which demonstrates the adequacy of the station electrical distributicn system at Maine Yankee.

8

_1

2.0 AUXILIARY POWER SYSTEM 2.1 Description The Maine Yankee auxiliary power system is shown in Figure 2.1.

Detailed portions of the auxiliary power system are shown as Figures 2.2 through 2.5.

During normal plant operation, power is supplied to the station auxiliary power system from the generator leads through unit station service transformers X24 and X26. Transformer X26 normally supplies power to 6900 volt bus 1 and bus 2.

Transformer X24 normally supplies power to 4160 volt bus 3 and bus 4.

4160 volt emergency bus 5 is connected to bus 3 by a normally closed tie breaker and likewise, 4160 volt emergency bus 6 is connected to bus 4.

Upon loss of their normal power source, the station auxiliary buses are automatically transferred to reserve station service transformers X14 and X16. Transformers X14 and X16 supply power from the 115 kV switchyard to the 4160 volt and 6900 volt buses respectively.

There are eight 480 volt buses fed from the 4160 volt buses by 4160/480 volt air cooled, dry-type transformers.

Bus 7 and bus 8 are the 480 volt emergency buses. They feed 460 volt motors and emergency motor control centers.

2.2 Voltage Requirements The offsite power system and onsite power distribution system at Maine Yankee are designed to provide adequate voltage to support the operation of required loads under all modes of plant operation.

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2.2.1 Offsite Power System Operating Voltage Range Two 115 kV transmission lines, one from Mason Station and one from Suroweic Substation supply the 115 kV switchyard.

Both Mason Station and Suroweic Subst cion are extensively interconnected with the 115 kV and 345 kV transmission network in the New England area.

Each station has a 345 kV/

115 kV automatic load tapchanging autotransformer which maintains station voltage at approximately 120 kV.

The analysis is based on an offsite power system operating voltage of 120 kV at Mason Station and Suroweie Substation.

The operating voltage range at Maine Yankee's 115 kV switchyard is determined by the analysis from transmission line load flow requirements.

2.2.2 Motors and Contactors Table 2.1 provides voltage requirements for the various motors and' contactors in the auxiliary power system.

The casis for the +10% operating voltage range of the various motors are NEMA standards; however, 4000 volt safety related motors were specified to start at 75% of rated voltage.

The basis for contactor pickup and dropout voltage is manufacturers' data.

Table 2.1 Motor and Contactor Voltage Requirements Maximum Minimum Minimum Operating Operating Starting Voltage Voltage Voltage (volts)

(volts)

(volts) 6900 Volt System 6600 volt motors 7260 5940 5940 4160 Volt System 4000 volt motors 4400 3600 3600 4000 volt motors 4400 3600 3000*

(safety related)*

480 Volt System 460 volt motors 506 414 414 460 volt contactors 506 414 370 (contactor pickup) 322 (contactor dropout) 2.2.3 Undervoltage Relay Setpoints Due to the critical nature and the requirements of the loads on energency buses 5 and 6, a Joss of voltage sensed by undervoltage relays will result in complete isolation of that bus from its normal source of supply and immediate starting of its associated emergency diesel generator.

The undervoltage relays are set to actuate in one second upon complete loss of power (dead bus) and in 8 seconds at 62% of rated bus voltage.

The relays will not actuate while voltage is above 78% of rated bus voltage.

Additional undervoltage relays have been installed on emergency buses 5 and 6 to alarm at 90% of rated bus volcage to protect the safety loads against undervoltage caused by degraded grid voltage. These relays

will provide an alarm if the bus voltage approaches or falls below their setpoint for a period exceeding 5 seconds.

The 5 second time delay has been provided to eliminate spurious pickup due to short duration voltage transients on the transmission grid or on the auxiliary power system. The operator has been provided with instructions on the action required should the above degraded voltage alarm be received.

3.0 ANALYSIS 3.1 Problem Statement Reference (a) required that analyses be performed to determine the voltage at each safety load, assuining the need for power is initiated by an anticipated transient (e.g., unit trip) or an accident, whichever presents the largest load demand. The analyses must consider all actions the electric power system is desigr.ed to automatically initiate including automatic transf ers of bulk loads f rom one transformer to another.

Furthermore, the analyses shall be based on the assumption that the grid voltage is at the

" minimum expected value".

In order to comply with these requirements, three cases were developed and evaluated:

Case I simulstes the voltage drop caused by transfer of auxiliary loads from the unit siocion service transformer to the reserve station service transformer with simultaneous start of safeguards loads. At Maine Yankee, an accident signal initiates a turbine trip which then initiates the transfer and start of safeguards loads.

The effect of transient inrush currents caused by the transfer are superimposed on the inrush currents caused by starting of safeguards loads.

Case 2 simulates the voltage drop caused by the start of safeguards loads from the reserve station service transformer with no transfer (plant auxiliary load powered by the reserve station service t rans fo rme r).

Case 3 simulates the steady state operation of the safeguards loads

and other auxiliary loads powered by the reserve station service t rans f o rme r.

Reference (a) also requires that analyses be performed to determine the maximum voltage at the terminals of each safety load. The analyses shall be based on the grid voltage at the maximum expected value and the plant load at the minimum load level.

In orde. to comply with this requirement, Case 4 was developed and evaluated. Case 4 simulates steady state operating voltages of auxiliary loads powered by the reserve station service transformer.

3.2 Method A computer solution of a load flow calculation is needed to determine each bus voltage in a power system because an iterative algorithm is required to solve numerous simultaneous equations. Load flow computer programs require as input such parameters as the load at each bus expressed in watts and vars and the impedance between each bus in the system. A model of the system ccntaining all loads and impedance values must be developed to provide this information.

Yankee Atomic Electric Company has performed the required voltage analysis in cooperation with Rhode Island, Eastern Massachusetts and Vermont Energy Control (REMVEC).

REMVEC is responsible for controlling generation and bulk transmission f or electric utilities located in the above areas.

REMVEC, in order to perform its load dispatch functions, performs daily load flow studies of the New England grid using the Power Systems Simulation Package, PSS/2, of Power Technologies Incorporated (PTI). This program package uses the Newton-Raphson and tne Gauss-Seidel techniques which are

used extensively for load flow solutions by the electric industry. The PSS/2 program package can solve both steady state and dynamic power system studies; including standard load flow studies, load flow switching studies, transient stability studies and motor starting calculations. The program software package is the property of PTI and is proprietory information.

3.3 Assumptions Figure 3.1 is a representation of a model used for the Maine Yankee load flow studies.

This representation shows the plant connected to the reserve station service transformer.

Special node numbers have been assigned for use in the 1 cad flow program; these numbers are shown enclosed by hexagons on Figure 3.1.

A group of loads assumed to be connected to a particular bus is represented on Figure 3.1 by the word " load" enclosed by a rectangle.

3.3.1 Impedance Model a)

The cable impedance (resistance and reactance) to the terminals of each safety load supplied from 4160 V switchgear buses 5 and 6 and 480 V switchgear buses 7 and 8 was calculated.

b)

The cable impedance of at least one representative load was calculated for each emergency motor control center. The representative load was selected as the load that would experience the worst voltage drop.

c)

Cable capacitance was neglected.

d) ir usformer impedances were cbtained from nameplates.

e) 7<casformer tap settings were verified by inspection.

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3.3.2 Maximum Load Model The loading assumptions for Cases 1, 2 and 3 are presented in Tables 3.1, 3.2 and 3.3 respectively. The following assumptions were used to develop these tables:

a)

The maximum load was determined to exist when an accident occurs without loss of offsite power.

b)

Motor watts and vars were conservatively calculated by using nameplate horsepower instead of the actual horsepower required.

c)

The loading for the 6900 V and 4160 V systems was determined from discussions with plant personnel, review of plant procedures and review of schematic diagrams.

d)

The 480 volt system loading was determined by a review of schematic diagrams and by conservatively assigning load factors to intermittent loads.

e)

For motor starting studies, all loads are converted to constant real current and constant imaginary reactance equivalents.

This conversion results in conservatively low voltage drops because all resistive loads are treated as motors.

f)

No load shedding occurs except for the pressurizer heaters which automatically trip and the reactor coolant ptmps which are manually tripped by procedure.

g)

The analysis is based on an offsite power system operating voltage

of 120 kV at Mason Station and Suroweic Substation. The minimun expected voltage used with the maximum load model is determined by the analysis f rom trans.J,sion line load flow requirements.

3.3.3 Minimum Load Model The loadir

.ssumptions for Case 4 are presented in Table 3.4.

The following assumptions were used to develop this table:

a)

In developing the minimum load model, the plant was assumed to be at cold shutdown with minimum operating load. This load consists of two component cooling water pumps, lighting load, and various other 480 volt system loads.

b)

The analysis is based on an offsite power system operating voltage of 120 kV at Mason Station and Suroweic Substation. The maximum expected voltage used with the minimum load model is determined by the analysis from transmission line load flow requirements.

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Table 3.1 Loading Ass umptions - Cas e 1 Condit ions :

Maximum Load Trans fer to Reserve Station Service Trans former Start Safeguards Loads Loads Starting Node Steady State Loading Simultaneously No.*

Description Before Trans fer With Trans fer 1

115 kV Switchyard 61 6.9 kV Buses 1 and 2 39,600 kvA 31 4.16 kV Bus 3 5,800 kVA 3

4.16 kV Bus 5 41 4.16 kV Bus 4 4,300 kVA 4

4.16 kV Bus 6 5

Charging Pump P-14A 800 hp 6

Primary Component Cooling Water Pump P-9A 300 hp 7

Containment Spray Pump P-61A 350 hp 9

Low Pressure Safety Injection Pump P-12A 400 hp 10 Low Pressure Safety Injection Pump P-12B 400 hp 11 Secondary Comp. Cooling Wtr. Pump P-10B 350 hp 12 Containment Spray Pump P-61B 350 hp 14 Charging PLnp P-14B 800 hp 15 480 Volt Bus 7 250 hp 16 480 Volt Bus 8 375 hp 17 Service Water Pump P-29A 250 hp 18 Service Water Pump P-29B 250 hp 19 480 Volt MCC 7A 335 kVA 16 hp 20 480 Volt MCC 7B 13 kVA 2 hp 21 480 Volt MCC 8B 13 kVA 22 480 Volt MCC 8A 213 kVA 15 hp 24 480 Volt MCC 7B1 25 kVA 5 hp 25 HCV-271 2 hp 26 480 Volt MCC 8B1 50 kVA 20 hp 27 Containment Air Compressor C-5B 7.5 hp 28 Control Air Compressor C-1A 29 Spray Pump Room Exhaus t Fan FN-44A 25 hp 30 Spray Pump Room Exhaust Fan FN-44B 25 hp See Figure 3.1

_17_

Table 3.2 Loading Assumptions - Case 2 Conditio ns :

Maximum Load Reserve Station Service Trans former Carrying Auxiliary Loads Start Safeguards Loads Node Safeguards No.*

Description Steady State Loading Loads Starting 1

115 kV Switchyard 61 6.9 kV Buses 1 and 2 39,600 kVA 31 4.16 kV Bus 3 5,800 kVA 3

4.16 kV Bus 5 41 4.16 kV Bus 4 4,300 kVA 4

4.16 kV Bus 6 5

Charging Pump P-14A 800 hp 6

Primary Component Cooling Water Pump P-9A 300 hp 7

Containment Spray Pump P-61A 350 hp 9

Low Pressure Safety Injection Pump P-12A 400 hp 10 Low Pressure Safety Injection Pump P-12B 400 hp 11 Secondary Comp. Cooling Wtr. Pump P-10B 350 hp 12 Containment Spray Pump P-61B 350 hp 14 Charging Pump P-14B 800 hp 15 480 Volt Bus 7 250 hp 16 480 Volt Bus 8 375 hp 17 Service Water Pump P-29A 250 hp 18 Service Water Pump P-29B 250 hp 19 480 Volt MCC 7A 335 kVA 16 hp 20 480 Volt MCC 7B 13 kVA 2 hp 21 480 Volt MCC 8B 13 kVA 22 480 Volt MCC 8A 213 kVA 15 hp 24 480 Volt MCC 7B1 25 kVA 5 hp 25 HCV-271 2 hp 26 480 Volt MCC 8B1 50 kVA 20 hp 27 Containment Air Compressor C-5B 7.5 hp 28 Control Air Compressor C-1A 29 Spray Pump Room Exhaus t Fan FN-44A 25 hp 30 Spray Pump Room Exhaust Fan FN-44B 25 hp See Figure 3.1 Table 3.3 Loading Assumptions - Case 3 Conditions :

Maximum Load Reserve Station Service Trans former Carrying Auxiliary Loads Node No.*

Description Steady State Loading 1

115 kV Switchyard 61 6.9 kV Buses 1 and 2 14,000 kVA 31 4.16 kV Bus - 3 5,500 kVA 3

4.16 kV Bus 5 41 4.16 kV Bus 4 4,200 kVA 4

4.16 kV Bus 6 5

Charging Pump P-14A 800 hp 6

Primary Component Cooling Water Pump P-9A 350 hp 7

Containment Spray Pump P-61A 350 hp 9

Low i _ essure Safety Injection Pump P-12A 400 hp 10 Low Pressure Safety Injection Pump P-12B 400 hp 11 Secondary Comp. Cooling Wtr. Pump P-10B 350 hp 12 Containment Spray Pump P-61B 350 hp 14 Charging Pump P-14B 800 hp 15 480 Vol t Bus 7 250 hp 16 480 Volt Bus 8 275 hp 17 Service Water Pump P-29A 250 hp 18 Service Wa ter Pump P-29B 250 hp 19 480 volt MCC 7A 340 kVA 20 480 Volt MCC 7B 13 kVA 21 480 Volt MCC 8B 13 kVA 22 480 Volt MCC 8A 213 kVA 24 480 Volt MCC 7B1 25 kVA 25 HCV-271 26 480 Volt MCC 8B1 50 kVA 27 Containment Air Compressor C-5B 7.5 hp 28 Control Air Compressor C-1A 75 hp 29 Spray Pump Room Exhaust Fan FN-44A 25 hp 30 Spray Pump Room Exhaus t Fan FN-44B 25 hp See Figure 3.1

_19

Table 3.4 Loading Assumptions - Case 4 Condit io ns :

Minimum Load Reserve Station Service Transformer Carrying Auxiliary Loads Node No.*

Descr iption Steady State Loading 1

115 kV Switchyard 61 6.9 kV Buses 1 and 2

'1 4.16 kV Bus '3 335 kVA 3

4.16 kV Bus 5 41 4.16 kV Bus 4 335 kVA 4

4.16 kV Bus 6 5

Charging Pump P-14A 6

Primary Component Cooling Water Pump P-9A 350 hp 7

Containment Spray Pump P-61A 9

Low Pressure Safety Injection Pump P-12A 10 Low Pressure Safety Injection Pump P-11B Secondary Comp. Cooling Wtr. Pump P-10B 350 hp 11 12 Containment Spray Pump P-61B 14 Charging Pump P-14B 15 480 Volt Bus 7 110 kVA 16 480 Volt Bus 8 110 kVA 17 Service Water Pump P-29A 18 Service Water Pump P-29B 19 480 Volt MCC 7A 20 480 Volt MCC 7B 21 480 Volt MCC 8B 22 480 Volt MCC 8A 24 480 Volt MCC 7Bl 25 HCV-271 26 480 Volt MCC 881 27 Containment Air Compressor C-5B 28 Control Air Compressor C-1A 29 Spray Pump Room Exhaust Fan FN-44A 30 Spray Pump Room Exhaust Fan FN-44B See Figure 3.1 4

4.0 CONCLUSION

S The results of the voltage study for Cases 1, 2, 3 and 4 are presented in Tables 4.1, 4.2, 4.3 and 4.4 respectively. These tables contain operating or motor starting voltages (as applicable) and the allowable voltage range.

The Case 1 and Case 2 results provide the maximum voltage drops when safeguards motors are required to start. Although we expected that the minimum voltages for Case 1 (transfer case) would be lower than the minimum voltages for Case 2 (no transfer), Tables 4.1 and 4.2 indicate that this is not true.

The Case 2 results contain lower minimum voltages, because the initial bus voltages when the station auxiliary loads are fed from the reserve station service transformer are lower than when the auxiliary loads are fed from the unit station service transformer.

The Case 2 results show that voltages in the 480 volt system drop comentarily to slightly lower than acceptable values when the large safeguards motors start.

This is of no concern because sufficient voltage exists for acceleration of all 4000 volt safeguards motors.

As the large safeguards motors accelerate (typically one to two seconds), voltage in the 480 volt sys em will recover sufficiently to ensure that 480 volt loads have adequate starting voltage and that they will start in an acceptable time.

An analysis to verify this has been performed. The computer studies were repeated with the 4000 volt motors drawing running current but with the 460 volt motor still drawing inrush current. These studies show that the 480 volt system voltages recover to above the minimum acceptable values.

The 480 volt systen voltage remains above any value that will cause undervoltage relay operation or cause contactors to drop out.

Case 3 demonstrates that under the worst case loading the voltage is adequate for the continuous operation of all loads. Voltages are above values that will cause initiation of undervoltage relays.

Case 4 demonstrates that under extreme light load conditions voltages at all buses are well within the maximum voltage limits for the operation of electrical equipment.

The study of the auxiliary power system at Maine Yankee was mace using the worst case loading, minimum expected grid voltage and other conservative assumptions. Therefore, we conclude that the auxiliary power system at Maine Yankee is of sufficient capacity to automatically start and operate all safety loads, assuming that all onsite power systems are not available.

Table 4.1 Bus and Equipment Terminal Voltages - Case 1 Conditiors:

Maximum Load Trans fer to Reserve Station Service Trans former Start Safeguards Loads Allokable Voltage Range Node Voltage (Volts )

No.*

Description-(Volts)

(Table 2.1) 1 115 kV Switchyard 117,000 61 6.9 kV Buses 1 and 2 31 4.16 kV Bus 3 4019 3

4.16 kV Bus 5 4019 41 4.16 kV Bus 4 4020 4

4.16 kV Bus 6 4020 5

Charging Pump P-14A 4015 4400-3000 6

Primary Component Cooling Water Pump P-9A 4016 4400-3000 7

Containment Spray Pump P-61A 4009 4400-3000 9

Low Pressure Safety Injection Pump P-12A 4017 4400-3000 10 Low Pressure Safety Injectir Pump P-12B 4009 4400-3000 11 Secondary Comp. Cooling Wtr Pump P-10B 4017 4400-3000 12 Containment Spray Pump P ' 1B 4012 4400-3000 14 Charging Pump P-14B 4009 4400-3000 15 480 Volt Bus 7 454 16 480 Volt Bus 8 454 17 Service Water Pump P-29A 447 506-414 18 Service Water Pump P-29B 447 506-414 19 480 Volt MCC 7A 453 506-414 20 480 Volt MCC 7B 449 506-414 21 480 Volt MCC GB 445 506-414 22 480 Volt MCC 8A 453 506-414 24 480 Volt MCC 7B1 445 506-414 25 HCV-271 448 506-414 26 480 Volt MCC 8B1 440 506-414 27 Containment Air Compressur C-5B 444 506-414 28 Control Air Compressor C-1A 29 Spray Pump Room Exhaus t Fan FN-44A 444 506-414 30 Spray Pump Room Exhaust Fan FN-44B 439 506-414 See Figure 3.1 Table 4.2 Bus and Equipment Terminal Voltages - Case 2 Conditions:

Maximum Load Trans fer to Reserve Station Service Trans former Start Safeguards Loads Allo wable

'Joltage Range Node Voltage (Volts)

No.*

Description (Vol ts )

(Table 2.1) 1 115 kV Switchyard 115,800 61 6.9 kV Buses 1 and 2 31 4.16 kV Bus 3 3608 3

4.16 kV Bus 5 3608 41 4.16 kV Bus 4 3608 4

4.16 kV Bus 6 3603 5

Charging Pump P-14A 3603 4400-3000 6

Primary Component Cooling Water. Pump P-9A 3605 4400-3000 7

Containment Spray Pump P-61A 3600 4400-3000 9

Low Pressure Safety Injection Pump P-12A 3607 4400-3000 10 Low Pressure Safety Injection Pump P-12B 3605 4400-3000 11 Secondary Comp. Cooling Wtr. Pump P-10D 3604 4400-3000 12 Containment Spray Pump P-61B 3599 4400-3000 14 Charging Pump P-14B 3598 4400-3000 15 4 80 Volt Bus 7 400 16 480 Volt Bus 8 39/

17 Service Water Pump P-29A 389#

506-414 18 Service Water Pump P-29B 388#

506-414 19 480 Volt MCC 7A 398#

506-414 20 480 Volt MCC 7B 395#

506-414 21 480 Volt MCC 8B 387#

506-414 22 480 Volt MCC 8A 396#

506-414 24 480 Volt MCC 7B1 391#

506-414 25 HCV-271 394#

506-414 26 480 Volt MCC 8B1 3814 506-414 27 Containment Air Compressor C-5B 386#

506-414 28 Control Air Compressor C-1A 29 Spray

• ump Room Exhaus t Fan FN-44A 390#

506-414 30 Spray u 7 Paom Exhaust Fan FN-44B 380#

506-414 See Figure 3.1

1. Ins tantaneous dip - voltage recovers to acceptable value as safeguards motors start Table 4.3 Bus and Equipment Terminal Voltages - Case 3 Conditions :

Maximum Load Reserve Station Service Transformer Carrying Auxiliary Loads Allowable Voltage Range Node Voltage (Volts )

No.*

Description (Volts)

(Table 2.1) 1 115 kV Switchyard 117,700 61 6.9 kV Buses 1 and 2 31 4.16 kV Bus 3 3886 3

4.16 kV Bus 5 3886 41 4.16 kV Bus 4 3886 4

4.16 kV Bus 6 3886 5

Charging Pump P-14A 3880 4400-3600 6

Primary Component Cooling Water ? ump P-9A 3883 4400-3600 7

Containment Spray Pump P-61A 3878 4400-3600 9

Low Pressure Safety Injection Pump P-12A 3878 4400-3600 10 Low Pressure Safety Injection Pump P-12B 3878 4400-3600 11 Secondary Comp. Cooling Wtr. Pump P-10B 3882 4400-3600 12 Containment Spray Pamp P-61B 3879 4400-3600 14 Charging Pump P-14B 3881 4400-3600 15 480 Volt Bus 7 437 16 480 Volt Bus 8 436 17 Service Water Pump P-29A 436 506-414 18 Service Water Pump P-29B 426 506-414 19 480 Volt MCC 7A 436 506-414 20 480 Volt MCC 7B 435 506-414 21 480 Volt MCC 8B 433 506-414 22 480 Volt MCC 8A 434 506-414 24 480 Volt MCC 7B1 434 506-414 25 HCV-271 26 4 80 Volt

• 8B1 431 506-414 27 Contai nment sir Compressor C-5B 429 506-414 28 Control Air Compreesor C-1A 422 506-414 29 Spray Pump Room Exhaus t Fan FN-44A 431 506-414 30 Spray Pump Room Exhaust Fan FN-44B 428 506-414 See Figure 3.1 8

o e

Table 4.4 Bus and Equipment Terminal Voltages - Case 4 Conditions :

Minimum Load Reserve Station Service Transformer Coarrying Auxiliary Loads Allokeble Node Voltage (Volts )

No.*

Description (Volts )

(Table 2.1) 1 115 kV Switchyard 120,000 61 6.9 kV Buses 1 and 2 31 4.16 kV Bus 3 4113 3

4.16 kV Bus 5 4113 41 4.16 kV Bus 4 4113 4

4.16 kV Bus 6 4113 5

Charging Pump P-14A 6

Primary Component Cooling Water Pump P-9A 4108 4400-3600 7

Containment Spray Pump P-61A 9

Low Pressure Safety Injection Pump P-12A 10 Low Pressure Safety Injection Pump P-12B 11 Secondary Comp. Cooling Wtr. Pump P-10B 4108 4400,-3600 12 Containment Spray Pump P-61B 14 Charging Pump P-14B 15 480 Volt Bus 7 474 16 480 Volt Bus 8 474 17 Service Water Pump P-29A 18 Service Water Pump P-29B 19 480 Volt MCC 7A 473 506-414 20 480 Volt MCC 7B 473 506-414 21 480 Volt MCC 8B 473 506-414 22 480 Volt MCC 8A 473 506-414 24 480 Volt MCC 7B1 473 506-414 25 HCV-271 26 480 Volt MCC 8B1 473 506-414 27 Containment Air Compressor C-5B 28 Control Air Compressor C-1A 29 Spray Pump Room Exhaust Fan FN-44A 30 Spray Pump Room Exhaust Fan FN-44B See Figure 3.1

[

e e

5.0 VERIFICATION Reference (a) required that the adequacy of the onsite and offsite power distribution systems be verified by test to assure that the analysis results are valid.

In lieu of actual tests, the computer load flow program and model of the auxiliary power system was used to predict bus voltages f or actual plant conditions. Two verifications were made. The results of the verification studies are provided in Table 5.1.

Comparison of bus voltages predicted by the computer program to actual bus voltages demonstrates that the computer model is valid.

e Table 5.1 Predicted Voltage Vs. Measured Voltage Verification #1 - December 6, 1979 - 0400 hours0.00463 days <br />0.111 hours <br />6.613757e-4 weeks <br />1.522e-4 months <br /> Predicted Voltage Measured Voltage Percent Deviation Bus (Volts)

(Volts)

(Percent) 6900 volt bus 1 6762 6800

.56 6900 volt bus 2 6762 6800

.56 4160 volt bus 3 4147 4250

-2.42 4160 volt bus 4 4147 4300

-3.56 4160 volt bus 5 4147 4200

-1.26 4160 volt bus 6 4147 4250

-2.42

(

480 volt bus 7 470 467

+.64 480 volt bus 8 471 466

+1.07 Verification #2 - December 8, 1979 - 1200 hours0.0139 days <br />0.333 hours <br />0.00198 weeks <br />4.566e-4 months <br /> Predicted Voltage Measured Voltage Percent Deviation Bus (Volts)

(Volts)

(Percent) 6900 volt bu s 1 6731 6800

-1.01 6900 volt bus 2 6731 6800

-1.01 4160 volt bus 3 4131 4230

-2.34 4160 volt bus 4 4131 4280

-3.48 4160 volt bus 5 4131 4200

-1.64 4160 volt bus 6 4131

-1.64 480 volt bus 7 468 462

+1.30 480 volt bus 8 468 466

+.43 Z

4 REFERENCES (a) Letter from United States Nuclear Regulatory Commission to All Power Reactor Licensees, Adequacy of Station Electric Distribution System Voltages, (August 8, 1979).

e*

6 9

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