ML20003F110

Adequacy of Station Electric Distribution Sys Voltages, Preliminary Technical Evaluation Rept

ML20003F110
Person / Time
Site:	Brunswick
Issue date:	03/31/1981
From:	Weber D EG&G IDAHO, INC., EG&G, INC.
To:	Shemanski P Office of Nuclear Reactor Regulation
References
CON-FIN-A-6429 EGG-EA-5389, NUDOCS 8104200180
Download: ML20003F110 (21)

Text

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P00R ORIGINAL March 1981 ADEQUACY OF STATION ELECTRIC DISTRIBUTION SYSTEM

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VOLTAGES, BRUNSWICK NUCLEAR POWER STATION UNITS 1 AND 2, DOCKET NOS. 50-325 AND 50-324 NlC Researca anc Tec1nical

o. A. ,,,,, N Assistance Report PMUMBMARY e e U.S. Department of Energy 4 a Idaho Operations Office

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This is an informal report intended for use as a preliminary or working document

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NSC Researc;i anc' Tec,inica' Prepared for the SSSI80CeSep0r[

U.S. Nuclear Regulatory Commission Under DOE Contract No. DE-AC07-76ID01570 0 b b E b Idaho FIN No. A6429 pg 8104200 @

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FORM EG&G 396 (Rev.1119)

INTERIM REPORT Accession No.

. Report No. EGC-EA-5389

~ C:ntract Program or Project

Title:

Selected Operating Reactors Issues Program (III)

Subject of this Document:

Adequacy of Station Electric Distribution System Voltages, Brunswick Nuclear Power Station Unit Nos 1 and 2 Type of Document:

Technical Evaluation Report Author (s):

D. A. Weber

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D:ta of Document:

NRC Researc1 anc ecinical

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March 1981 Ass.is~ance Report Responsible NRC Individual and NRC Office or Division:

Paul C. Shemanski, Division of Licensing This document was prepared primarily for preliminary or internal use. it has not received full review and approval. Since there may be substantive changes,this document should not be considered final.

EG&G Idaho, Inc.

Idaho Falls, Idaho 83415 Prepared for the U.S. Nuclear Regulatory Commission

'Nashington, D.C.

Under DOE Contract No. DE-AC07 761D01570 NRC FIN No. A6429 INTERIM REPORT

0313J ADEQUACY OF STATION ELECTRIC OISTRIBUTION SYSTEM VOLTAGES BRUf6 WICK NUCLEAR POWER STATION UNIT NOS.1 AND 2 Docket Nos. 50-325 and 50-324 March 1981 D. A. Weber Reliability and Statistics Branch Engineering Analysis Divisicn EG&G Idaho, Inc.

NRC Research anGechnical

. Assistance ' Report

. TAC Nos. 12829 and 12830

ABS TRACT The Nuclear Regulatory Commission has required all licensees to analyze the electric power system at each nuclear station. This review is to deter-mine if the onsite distribution system in conjunction with the offsite. power sources has sufficient capacity and capability to automatically start and operate all required safety loads within the equipment voltage ratings.

This Technical Evaluation Report reviews the submittals for the Brunswick Nuclear Power Station.

The offsite power sources, in conjunction with the onsite distribution system, have been shown to have sufficient capacity and capability to auto-matically start as well as continuously operate, all required safety related 4

loads within the equipment rated voltage limits in the event of either an anticipated transient or an accident condition.

i FOREWORD This report is supplied as part of the " Selected Operating Reactor Issues Program (III)" being conducted for the U.S. Nuclear Regulatory Commission, Office of Nuclear Reactor Regulation, Division of Licensing, by EG&G Idaho, Inc., Reliability and Statistics Branch.

The U.S. Nuclear Regulatory Commission funded the work under the authorization, B&R 20 19 01 06, FIN No. A6429.

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\ RC lesearcl anc Tec1nical Assistance Report I

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CONTENTS

1.0 INTRODUCTION

...........................................;.......... 1 2.0 D ES I G N B AS IS CR I T ER I A . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1 3.0 S YS TEM D ES CR I P T I O N . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 2 4.0 AN AL YS IS D ES CR I P T I O N . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 4 4.1 Analysis Conditions ....................... 7................. 4 4.2 Analysis Results .........................../.................. 5 4.3 Analysis Verification ................... 5

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5.0 EVALUATION .................................../.................... 5 6.0 C O N C L US I O NS . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . , . . . . . . . . . . . . . . . . . . . . . . 9

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7.0 REFERENCES

................................ ....................... . 10 APPENDIX A--EXPLANATION OF ANALYZED VOLTAGES IN TABLES 1 AND 2 ......... 11 FIGURE

1. Brunswick Nuclear Power Station electrical single-line diagram ........................................................... 3 TABLES

1. Class lE Equipment Voltage Ratings and Analyzed Worst Case Load Terminal Voltages ........................ 6

2. Comparison of Analyzed Voltages and Undervoltage Relay Setpoints ...................................... 7 l

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l. YlC Research anc' Tecmica Assistance Repor':

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ADEQUACY OF STATION ELECTRIC DISTRIBUTION SYSTEM VOLTAGES BRUNSWICX NUCLEAR POWER STATION UNIT NOS.1 AND 2

1.0 INTRODUCTION

An event at the Arkansas Nuclear One station on September 16, 1978 is described in NRC IE Information Notice No. 79-04. As a result of this event, station conformance to General Design Criteria (GDC) 17 is being questioned at all nuclear power stations. The NRC, in the generic letter of August 8,1979, " Adequacy of Station Electric Distribution Systems Volt-ages," I required each licensee to confirm, by analysis, the adequacy of the voltage at the class lE loads. This letter included 13 specific guide-lines to be followed in determining if the load terminal voltage is adequate to start and continuously operate the class lE loads.

The Carolina Power and Light Company (CP&L) responded to the NRC letter on October 8, 1979.2 This submittal, the submittals of July 24, 1980,3

- October 15, 1980,4 December 2, 1980,5 February 16, 19816 , the EG&G Idaho, Inc., report on the Brunswick Units I and 2 degraded grid pro-

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tection,7 and the Final Safety Analysis Report (FSAR) complete the infor-mation reviewed for this report.

Based on the information supplied by CP&L, this report addresses the capacity and capability of the onsite distribution system of the Brunswick Nuclear Power Station, in conjunction with the offsite power system, to maintain the voltage for the required class lE equipment within acceptable limits for the worst-case starting and load conditions.

2.0 DESIGN BASIS CRITERIA The positions applied in determining the acceptability of the offsite voltage conditions in supplying power to the class IE equipment are derived from the following:

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XRC Researc1 anc eclnical Assistance Report 1

1. General Design Criterion 17 (GDC 17), " Electrical Power Systems,"

of Appendix A, " General Design Criteria for Nuclear Power Plants,"

of 10 CFR 50.

2. General Design Criterion 5 (GDC 5), " Sharing of Structures, Sys- - '

tems, and Components," of Appendix A, " General Design Criteria ,

for Nuclear Power Plants," of 10 CFR 50.

3. General Design Criterion 13 (GDC 13), " Instrumentation.and Con-trol," of Appendix A, " General Design Criteria for Nucle'ar Power Plants," of 10 CFR 50.

4. IEEE Standard 308-1974, " Class lE Power Systems for N'u clear Power Generating Stations."

5. Staff positions as detailed in a letter sent to the licensee, dated August 8, 1979.I

6. ANSI C84.1-1977, " Voltage Ratings for Electric Power Systems and .

Equipment (60 Hz)."

Six review positions have been established from the NRC analysis guide-l lines and the above-listed documents. These positions are' stated in Section 5.0.

3.0 SYSTEM DESCRIPTION A single-line diagram of the AC electrical distribution system at Brunswick 'Jnits 1 and 2 is shown in Figure 1. The breaker positions, open, or closed, are shown for normal full-power plant operation.

The following system description pertains to Unit 2; Unit 1 is similar.

During normal full-power plant operations, the 1E and non-1E distribu-tion systems are supplied from the Unit Auxiliary Transformer 2 (UAT-2).

The Common B bus distribution system is supplied by the Startup Auxiliary -

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Transformer 2 (SAT-2). Protection relays or a unit trip results in the automatic fast transfer of loads from the UAT to the Startup Auxiliary Transformer 2 (S AT-2). The SAT can be supplied from two independent 230kV sources (not shown).

The lE distribution system consists of two independent and redundant .

trains; each train capable of supplying the required emergency loads.

The lE 4160V buses supply the 4kV motor, 4160-480/277V unit. substations E7 and E8, and 480V motor control centers (MCCs) and their loads. Control circuits for the 4160V circuit breakers are supplied from the 125/250V DC battery system and from individual 480/120V control power transformers for the MCC control circuits and circuit breakers.

Regarding Unit and bus tie breakers, CP&L states that (a) the tie breaker between non-lE Bus 28 and Bus 18 can only be closed if one of the incoming bus breakers from the SATs in Unit 2 or Unit 1 is open and one of the disconnect links (2A91 in Unit 2 or 1A91 in Unit 1) is removed, (b) the tie breaker between non-lE 4160V Common B of Unit 2 and Common A of Unit 1 -

can only be closed if the incoming bus line breaker to one of the buses is l open, (c) the lE tie breakers between IE 4160V E4 or E2 and between E3 and El are normally open, and an accident signal will cause them to trip should they be closed, and (d) the lE tie breakers between E4 and E3 have been disconnected and racked out. The 480V tie breakers between EB and E7 (not shown) are normally open.

4.0 ANALYSIS DESCRIPTION

! 4.1 Analysis Conditions. CP&L has determined, by load flow studies and review of recordings, that the maximum expected ( '# site 230kV grid voltage is 234.6kV (1.02 pu) and the minimum 220.8kV (0.96 pu).

CP&L has analyzed each offsite source to the onsite distribution system under extremes of load and offsite voltage conditions to determine the .

terminal voltages to lE equipment. The worst case class lE equipment ter-minal voltages occur under the following conditions: -

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1. The maximum voltages occur when the 230kV grid is at its maximum value, Unit 1 is shut down, and SAT-2 is supplying the minimum plant auxiliary loads.

2. The minimum steady-state voltages occur when the 230kV grid is at its minimum value concurrent with a LOCA in Unit 2 and a simul-taneous shutdown cooling of Unit 1, and SAT-2 is supplying all Unit 2 lE and non-lE loads and the non-lE loads from Unit 1 Com-mon A bus (tie breaker between Coninon B and Common A bus closed .

and all other tie breakers open).

3. The minimum transient voltages occur under conditions of 2 above, except for the starting of all RHR and Core Spray System pumps due to the LOCA in Unit 2 and' simultaneous shutdown of Unit 1.

4.2 Analysis Result. Table 1 shows the projected worst case class lE equipment terminal voltages. Table 2'shows a comparison of the analyzed

. voltages with the undervoltage relay setpoints. The analyzed values in these tables are calculated from information supplied by CP&L and are explained in Appendix A.

4.3 Analysis Verification. The CP&L letter of October 15, 1980, 4 describes the test to be used to verify the analysis. A telecon on December 19, 1980,0 provided additional information. Steady state vol-tage measurements will be made at the lE buses and 230kV grid. Then, one of the non-lE 4kV circulating water pumps will be started followed by the start of one of the 1E 460V screen wash pumps. The 230kV measured grid l voltage will be used as a basis for calculating the voltages at the lE j buses. The calculated voltages will then be compared with the measured voltages. The test is scheduled to be performed near the end of January 1981.5 ,

, 5.0 EVALUATION Six review positions have been established from the NRC analysis I

guidelines and the documents listed in Section 2.0 of this report.

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TABLE 1 CLASS 1E EQUIPMENT VOLTAGE RATINGS AND ANALYZED WORST CASE TERMINAL VOLTAGES

(% of nominal voltage)

Maximum Minimum ,

a Analyzed b c Eouipment Condition Rated Analyzed Rated Steady State Transient 4000V Motors Start -- -- 75 --

76 Operate 110 lild 90 92.7 --

460V Motors Start -- -- 85 --

74 Operate 110 lild 90 91 --

480V Starters Pickup -- -- 85 --

72 Dropout -- --

70 --

72 Operate 110 107 85 87.9 --

Other Pickup -- --

90 --

70.2 '

Equipmente Dropout -- -- 70 --

70.2 Operate 110 ll6d 90 90 --

a. Analyzed voltages corrected for minimum grid voltage of 96%.

b. Analyzed voltages corrected for maximum grid voltage of 102%.

c. Transient due to start of 4kV motors: other IE equipment is operating. 460V motor transient = 70.7%

i d. When the units are tripped, the switchyard voltage is expected to drop to 98%, which would result in voltages below the 110% maximum equipment safety.

j e. All relay coils, solenoids, and instruments.6 l

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TABLE 2 COMPARISON OF ANALYZED VOLTAGES AND UNDERVOLTAGE RELAY SETP0INTS

(% of nominal voltage)

Minimum Analyzed a Relay Setpoint 7 Location / Relays Voltage Time Voltage (Tolerance) lime 4160V busa Degraded grid 89.8 continuous 89.5 2 0.2 .10 sec 0.5 Loss of grid 74.87 less than 71.0 4.0 10 sec 10 sec8

a. Licensee has determined by analysis the minimum bus voltages with the offsite grid at the minimum expected voltage and the worst case plant and class 1E loads.

Each review position is stated followed by an evaluation of the licensee

- submittals.

Position 1--With the minimum expected offsite grid voltage and maximum load condition, each offsite source and distribution system connection ccmbination must be capable of starting and of continuously operating all class lE equipment within the equipment voltage ratings.

CP&L has shown, by analysis, that the Brunswick Nuclear Power Station has sufficient capability and capacity for starting and continuously oper-ating '.he class lE loads within the equipment voltage ratings (Table 1).

PositionJ --With the maximum expected offsite grid voltage and minimum load condition, each offsite source and distribution system connection combination must be capable of continuously operating the required class lE equipment without exceeding the equipment voltage ratings.

CP&L has shown, by analysis, that the voltage ratings of the class lE equipment will not be exceeded.

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Position 3--Loss of offsite power to either of the redundant class lE distribution systems due to operation of voltage protection relays, must not occur when .the offsite power source is within expected voltage limits.

As shown in Table 2, voltage relays will not cause loss of class 1E distribution systems when the offsite grid voltage is within expected volt-age limits. Also, see position 6.

Position 4--The NRC letter requires that test results verify i;he accuracy of the voltage analyses supplied.

CP&L indicates that test results will be available near the end of March 1981.5 The proposed test is acceptable if the test values used are obtained when the lE buses are loaded to at least 30%.

Position 5--No event or condition should result in the simultaneous or consequential loss of both required circuits from the offsite power network to the onsite distribution system (GDC 17). .

CP&L has analyzed the lE connections to the offsite power grid, and

• determined that no potential exists for simultaneous or consequential loss of both circuits from the offsite grid.

Position 6--As required by GDC 5, each offsite source shared between units in a multi-unit station must be capable of supplying adequate starting and operating voltage for all required class lE loads with an accident in one unit and an orderly shutdown and cooldown in the remaining units.

The Brunswick Nuclear Power Station is the site of two nuclear units.

! CP&L has indicated that the tie breaker between Units 1 and 2 is open during normal full-power operations, except that the tie breaker between Common A and Common B may be closed0 'O . The status and use of these tie ,

breakers is described in Section 3.0 of this report. Included in the CP&L analysis is the case where SAT-2 is supplying all Unit 2 loads with the tie -

breaker between Common A and Common 8 bus closed and a LOCA in Unit 2 and a

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A false LOCA signal in Unit 1.6 It should be noted that the CP&L analysis considers terminal voltages to non-lE equipment as well as lE equipment.

Although Tables 1 and 2 (based on a grid voltage of 0.96 pu) show satis-factory voltages for the lE equipment, the CP&L report recognizes degraded conditions for non-1E equipment, which indicates that the switchyard volt-age should not be degraded below 97.2%. Therefore, CP&L has proposed modi-fications should the grid degrade to 97.2% and the tie Dreaker between Common A bus and Common B bus is closed. These modifications would improve the minimum values noted in Tables 1 and 2.

6.0 CONCLUSION

S .

The voltage analyses submitted by CP&L for the Brunswick Nuclear Power Station were evaluated in Section 5.0 of this report. It was found that:

1. Voltages within the operating limits of the class lE equipment are supplied for all projected combinations of plant load and

, normal offsite power grid conditions; including an accident in one unit and the safe shutdown of the other unit.

2. The proposed test will verify that the accuracy of the analysis is satisfactory if the test measurements are made with the lE buses and MCCs loaded to at least 30% of their full load rating.

If this is not possible, CP&L should demonstrate that each bus or MCC is loaded sufficiently and the instrumentation is accurate enough to ensure the correct readings.

l l

l 3. CP&L has determined that no potential for either a simultaneous or consequential loss of both offsite power sources exists.

l 4. Loss of offsite power to class IE buses, due to spurious opera-tion of voltage protection relays, will not occur with the off-site grid voltage within its expected limits.

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7.0 REFERENCES

1. NRC letter, William Gammill, to All Power Reactor Licensees (Except' Humboldt Bay), " Adequacy of Station Electric Distribution Systems .

Voltage," August 8,1979.

2. CP&L letter, E. E. Utley, to Office of Nuclear Reactor Regulation, '

October 8, 1979.

3. CP&L letter, E. E. Utley, to Office of Nuclear Reactor Regulation, July 24, 1980.

4. CP&L letter, E. E. Utley, to Office of Nuclear Reactor Regulation, October 15, 1980.

5. CP&L letter, E. E. Utley, to Office of Nuclear Reactor Regulation, December 2, 1980.

6. CP&L letter, E. E. Utley, to Office of Nuclear Reactor Regulation, February 16, 1981.

7. EG&G, " Technical Evaluation Report of the Degraded Grid Protection for Class lE Power Systems for the Brunswick Steam Electric Plant Unit Nos. I and 2," February 1980.

8. Telecon, D. A. deber, EG&G Idaho, Inc., D. C. Stadler, CP&L, -

December 12, 1980.

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APPENDIX A EXPLANATION OF ANALYZED VOLTAGES IN TABLES 1 AND 2 CP&L's submittal of February 16, 1981,6 included Revision 2 of their original voltage drop study. On page 6 of this revised study, they stated that the switchyard has a " desired operating range" of 96% to 102%. On page A2, they state that the study is based on a switchyard range of 95% to 105% of the 230kV voltage for the SAT cases and 95% to 110% of the 24kV voltage for the UAT cases. Since the desired switchyard range is 96% to 102%, it was necessary to adjust the values in their tables on pages A3 to A25 and 83 to B6 to reflect this desired range. It was fcund that the maximum voltages at the IE equipment occur for the " SAT Shutdown" condi-tion (page All), the minimum steady-state occurs for the "2 x LOCA RUN" ccndition (page 85), and the minimum transient voltages occur for the "2 x LOCA START" condition (page 84). The cases analyzed on pages B3 to B6 consider the tie breaker between the Common A and Common B buses closed.

The cases on pages A3 to A5 consider this breaker open.

In addition, the steady-state maximum and minimum voltage cases (pages All and 85) did not show the 480V motor control center (MCC) bus voltages or the 4kV and 460V motor terminal voltages. However, it was possible to determine these voltages. Page 10 compares the voltages of the Unit Substations E7 and E8 to the MCCs, and the motor starting cases show the voltage differences between the Unit Substation and the MCCs and between the MCCs and the motor terminals for the motor starting (transient) condi-tions. The worst-case motor starting condition occurs when the Unit Sub-station E7 is supplying MCC 2PA (page 83) during a motor start, which results in a 24V drop between the Unit Substation and the MCC. Page 10 indicates that there is a 10V drop between Unit Substation E7 and the MCCs for the steady-state condition. Therefore, the steady-state value is approximately 42% of the transient value (10 + 24). The 42% is a reason-able relationship between the transient and steady-state values (if not somewhat conservative) and was used to determine the 1E equipment steady-state values when the transient values were available.

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Tables 1 and 2 follow with notes.

TABLE 1 CLASS lE EQUIPMENT VOLTAGE RATINGS AND ANALYZED WORST CASE TERMINAL V0LTAGES

(% of nominal voltage)

Maximum Minimum Analyzed a b

Equipment Condition Rated Analyzed Rated 5teady State Transient

• 4000V Motors Start -- -I 75 -2 76 3 Operate 110 lild 90 92.7 --

460V Motors Start 4 85 -. 74 6 Operate 110 lild 90 91 5 __

480V Starters Pickup -- --

85 --

72 9 Dropout -- --

70 --

72 9 Operate 110 107 7 85 87.9 8 __

12 Other Pickup -- --

90 --

70.2 Equipment

• Dropout 70 70.2

--))

- 10 Operate- 110 ll6d 90 90 --

a. Analyzed voltages based minimum grid voltage of 96%.

b. Analyzed voltages based on maximum grid voltage of 102%.

c. Transient due to start of 4kV motors: other IE equipment is operating. 460V motor transient = 70.7%

d. When the units are tripped, the switchyard voltage is expected to drop to 98%, which would result in voltages below the 110% maximum equipment safety.

e. All relay coils, solenoids, and instruments.

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TABLE 2 COMPARIS0N OF ANALYZED VOLTAGES AND UNDERV0LTAGE RELAY SETPOINTS

(% of nominal voltage)

Minimum Analyzed a Relay Setpoint Location / Relays Voltage Time Voltage (Tolerance) Time a

4160V bus 13 Degraded grid 89.8 continuous 89.5 0.2 10 sec 14 0.5 Loss of grid 74.87 less than 71.0 ! 4.0 10 sec 10 sec

a. Licensee has determined by analysis the minimum bus voltages with the offsite grid at the minimum expected voltage and the worst case plant and class lE loads.

I. 4kV Motor Terminal Voltage 1 Maximum steady state (SAT LIGHT LOAD)

From page A20 (LOCA START):

E3/E4 buses = 3,152V 4kV motor = 3,123V (RHR-2A)

Transient voltage drop = 29V (3,152 - 3,123)

Steady-state (S.S.) voltage drop = 12V (29 x 0.42)

From page All (SAT SHUTOOWN):

Switchyard = 232,068V Desired = 234,600V (1.02 x 230kV)

% Difference = 101.09% (234,600 + 232,068)

Buses E3/E4 = 4,409V Therefore, 4kV Buses E3/E4 = 4,457V (4,409 x 1.0109)

= 107.14% (4,457 + 4160)

Therefore, 4kV motor = 4,445V (4,457 - 12) l = 111% (4,445 + 4,000) i 1

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_ ._ - - - _ _ -_-~ _ -

2 Minimum Steady State (2 x LOCA RUN)

From page B4 (2 x LOCA START):

E3/E4 buses = 3,154V

= 3,084V Core Spray Pump 2B Transient voltage drop = 70V (3,154 - 3,084)

S.S. voltage drop = 29V (70 x 0.42) -

From page 85 (2 x LOCA RUN):

Switchyard = 217,580V Desired = 220,800 (0.96 x 230kV)

% difference = 101.48% (220,800 + 217,580)

Buses E3/E4 = 3,681V Therefore, Buses E3/E4 = 3,735V (1.0148 x 3,681)

= 89.8% (3,735 + 4,160)

Therefore, 4kV motor = 3!7DeV (3,735 - 29)

= 92.7% (3,706 + 4,000) 3 Minimum Transient (2 x LOCA START)

From page B4 (2 x LOCA START):

Switchyard = 223,560V Desired = 220,800V (0.96 x 230kV)

% difference = 98.76% (220,800 + 223,560) .

Buses E3/E4 = 3,154V Therefore, Buses E3/E4 = 3,ll5V (3,154 x 0.9876) '

= 74.87% (3,115 + 4160)

Core Spray Purp 2B = 3,084V Therefore, motor = 3,045V (3,084 x 0.9876)

= 76% (3,045 + 4,000)

II. 460V Motor Terminal Voltace 4 Maximum Steady State (SAT LIGHT LOAO)

From page A16 (SCREEN WASH PUMP 2A STARTING):

Sub E7 , = 423V MCC 2PA = 398V l Transient voltage drop = 25V (423 - 398) l MCC 5.S. voltage drop = 10V (25 x 0.42)

Screen Wash Pump 2A = 39TV ,

Transient voltage drop = 7V (398 - 391)

Motor S.S. voltage drop = 3V (7 x 0.42) t l

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From page All (SAT SHUTDOWN) and 1:

Switchyard % difference = 101.09% (from 1)

Therefore, Sub E7 = 525V (519 x 1.0109)

MCC 2PA = 515V (525 - 10)

= 107% (515 + 480)

Screen Wash Pump 2A = 512V (515 - 3)

, = 111% (512 + 460) 5 Minimum Steady State (2 x LOCA RUN)

From page B5 (2 x LOCA RUN), 2 , and 4:

Switchyard % differer.ce = 101.48% (from 2)

Therefore, Sub E7 = 432V (426 x 1.0148)

MCC 2PA = 422V (432 - 10) -

= 87.9% (422 + 480)

Screen Wash Pump 2A = 419V (422 - 3)

= 91% (419 + 460) 6 Minimum Tran'ient (2 x LOCA START)

From page B4 (2 x LOCA START), 3:

Switchyard % difference = 98.76% (from 3)

Sub E7 = 358V Therefore, Sub E7 = 354V (358 x 0.9876)

MCC 2PA = 344V (354 - 10)

= 71.7% (344 + 480)

Screen Wash Pump 2A = 341V (344 - 3)

= 74% (341 + 460)

III. 480V Motor Starter Voltace 7 Maximum Steady State (SAT LIGHT LOAD)

From 4: ,

MCC 2PA = 515V (MCC 2PA bus voltage =

motor starter voltage)

Therefore, 480V motor = 107% (515 + 480) starters 8 Maximum Steady State (2 x LOCA RUN)

From 5 MCC 2PA = 422V Therefore, 460V motor = 87.9% (422 + 480)

, starters 15

O 9 Minimum Transient (2 x LOCA START) -

From 6:

MCC 2PA = 344V '

Therefore, 480V motor = 72% (344 + 480) starters IV. Other Equipment: Rated ll5V (from 280/120V study)8 10 Maximum Steady State (SAT LIGHT LOAD)

From page 7:

Study was based on a switchyard voltage of 100.9% (232,070V).

Therefore, the maximum values will have to be adjusted for the desired switchyard voltage of 102%

Therefore, switchyard = 232,070V (from page 7)

Desired = 234,600V (1.02 x 230kV)

% difference = 101.09% (234,600 + 232,070)

From page 4:

Maximum voltage = 132.16V Adjusted maximum S.S. = 133.6V (132.16 x 1.0109)

Therefore, ll5V equipment = 116% (133.6 + 115) -

11 Minimum Steadv State (2 x LOCA RUN) .

From page A2:

Sub E7 = 426V

= 0.8875 (426 + 480)

From 4 St.h E7 = 423V

= 0.8813 (423 + 480)

Therefore, the values on page A2 reasonably reflect a minimum grid voltage of 96%

From bottom of page 6, it is stated that, if the Unit Substations are at least 0.8876 for E7 and 0.8803 for E8, all relay coils, solenoid, and instrumentation voltages will be above 90% of their rated voltage (ll5V).

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12 Minimum Transient Voltages (2 x LOCA START)

From page A2 and 6 Sub E7 = 426V (from page A2)

Sub E8 = 423V (from page A2)

Difference = 3V (426 - 423)

Therefore, if Sub E7 = 354V (from 6)

Then, Sub E8 = 351V (354 - 3)

If, Sub ES = 423V (from page A2) and 2C0 = 409V (from page A2)

Difference = 14V (423 - 409)

Therefore, if E8 = 351V Then, 2C0 = 337V (351 - 14)

= 70.2% (337 + 480)

V. Table 2 13 Minimum Analyzed Voltages--Degraded Grid From 2 (2 x LOCA RUN), 4160V Buses E3/E4 = 89.8%

14 Minimum Transient Voltage--Loss of Grid From 3 (2 x LOCA START), 4160V Buses E3/E4 = 74.87%

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