ML20062L204

Technical Evaluation Rept,Adequacy of Station Electric Distribution Sys Voltages,James a Fitzpatrick Nuclear Power Station,Docket No 50-333, Interim Rept

ML20062L204
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Site:	FitzPatrick
Issue date:	01/31/1981
From:	Weber D EG&G, INC.
To:	Shemanski P Office of Nuclear Reactor Regulation
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CON-FIN-A-6427 EGG-EA-5340, NUDOCS 8208180267
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Enclosure 2 f EGG-EA-5340 January 1981 l

i TECHNICAL EVALUATION REPORT, ADEQUACY OF STATION  ;

ELECTRIC DISTRIBUTION SYSTEM VOLTAGES, '

l l JAMES A. FITZPATRICK NUCLEAR POWER STATION,  !

DOCKET No. 50-333 ,

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I U.S. Department of Energy Idaho Operations Office

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-_ j This is an informal report intended for use as a preliminary or working document l I

i Prepared for the  !

U.S. Nuclear Regulatory Comission l Under DOE Contract No. DE-AC07-76ID01570 FIN No. A6429 0 Idaho i

8208180267 820802 yQ  !

PDR ADOCK 05000333 P PDR

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FORM EG&G 396 (Rev 117%

INTERIM REPORT Accession No.

Report No. EGG-EA-5340 Contract Program or Project

Title:

Electrical, Instrumentation and Control System Support Subject of this Document:

Adequacy of Station Electric Distribution System Voltages, James A. FitzPatrick Nuclear Power Station Type of Document:

Technical Evaluation Report Author (s):

D. A. Weber Date of Document:

January 1981 Responsible NRC Individual and NRC Office or Division:

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

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1 EG&G Idaho, Inc.

l Idaho Falls, Idaho 83415 l Prepared for the U.S. Nuclear Regulatory Commission Washington, D.C.

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

0151J ADEQUACY OF STATION ELECTRIC DISTRIBUTION SYSTEM VOLTAGES JAMES A. FITZPATRICK NUCLEAR POWER STATION Docket No. 50-333 January 1981 D. A. Weber Reliability and Statistics Branch Engineering Analysis Division EG&G Idaho, Inc.

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TAC No. 13156 l

ABSTRACT 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 reviuws the submittals for *.he James A. FitzPatrick Nuclear Power Station.

The offsite power sources, in conjunction with the onsite distribution system, have been shown to have sufficient capacity and capability to con-tinuously operate all required safety-related loads, within the equipment rated voltage limits, in the event of either an anticipated transient or an accident condition.

FOREWORD This report is supplied as part of the selected Electrical, Instrumen-tation, and Control Systems (EICS) issues program being conducted for the U.S. Nuclear Regulatory Commission, Of fice of Nuclear Reactor Regulation, Division of Operating Reactors, by EG&G Idaho, Inc., Reliability and Statis-tics Branch.

The U.S. Nuclear Regulatory Commission funded the work under the auth-orization entitled " Electrical, Instrumentation, and Control System Sup-port," B&R 20 19 01 03, FIN No. A6256.

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O CONTENTS

1.0 INTRODUCTION

...................................................... 1 2.0 D ES IG N B AS I S C RITE RI A . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1 3.0 SYSTEM DESCRIPTION ................................................ 2 4.0 ANALYSIS DESCRIPTION .............................................. 2 4.1 Design Changes ............................................... 2 4.2 Analysis Conditions .......................................... 4 4.3 Analysis Results ............................................. 5 4.4 Analysis Verification ........................................ 5 5.0 EVALUATION ........................................................ 5

6.0 CONCLUSION

S ....................................................... 7

7.0 REFERENCES

........................................................ 7 FIGURE

1. James A. FitzPatrick electrical single-line diagram ............... 3 TABLES

1. Class 1E Equipment Voltage Ratings and Analyzed Worst Case Load Terminal Voltages ........................ 4

2. Comparison of Analyzed Voltages and Undervoltage Relay Setpoints ...................................... 6 i

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ADEQUACY OF STATION ELECTRIC DISTRIBUTION SYSTEM VOLTAGES JAMES A. FITZPATRICK NUCLEAR POWER STATION ,

1.0 IKrRODUCTION i

An event at the Arkansas Nuclear One station on September 16, 1978 is i 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- I ages," I required each licensee to confirm, by analysis, the adequacy of the voltage at the class 1E loads. Tats 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 1E loads. -

The Power Authority of the State of New York (PASNY) submitted a letter dated September 7, 1979,2 which referred to previous submittals of -

October 18, 1976,3 December 31, 1976,4 July 13, 1977,5 and October 17, 1977,6 regarding operation of safety-related equipment under degraded grid conditions. These submittals, the Final Safety Analysis Report (FSAR) and a submittal of July 1, 1980,7 (response to a request for additional information), complete the information reviewed for this report.

Based on the information supplied by PASNY, this report addresses the capacity and capability of the onsite distribution system of the James A. FitzPatrick Nuclear Power Station (JAFNPS), in conjunction with l the offsite power system, to maintain the voltage for the required class 1E l equipment within acceptable limits for the worst-case starting and load conditions.

2.0 DESIGN BASIS CRITERIA i

The positions applied in determining the acceptability of the offsite voltage conditions in supplying power to the class 1E equipment are derived from the following:  ;

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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 struc- '

tures, Systems, and Components," of Appendix A, " General f

' Design Criteria for Nuclear Power Plants," of 10 CFR 50.

3. General Design Criterion 13 (GDC 13), " Instrumentation and Control," of Appendix A, " General Design Criteria for Nuclear Power Plants," of 10 CFR 50.

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I 4. IEEE Standard 308-1974, " Class 1E Power Systems for  !

Nuclear Power Generating Stations."

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5. Staff positions as detailed in a letter sent to the licensee, dated August 8, 1979.1

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-linesl and the above-listed documents. These positions are stated in Section 5.0.

3.0 SYSTEM DESCRIPTION Figure 1 of this report is a simplified sketch of the unit single-line diagram.

The class 1E distribution system supplies offsite power from two reserve station service transformers, T2 and T3, connected to the 115kV switchyard and one normal station service transformer, T4, connected to the 345kV switchyard. During plant operations, the safety-related and nonsafety-related buses are supplied by transformer T4. Automatic fast transfer from T4 to T2 and T3 is initiated by generator protective relays, reactor trip, or when the 4160V bus voltage falls below a predetermined value, independant of generator or reactor trip.

The class IE distribution system consists of two redundant and inde -

pendent trains. Transformer T2 supplies one train and T3 supplies the other via an independent 4160V normal buses. Each train is capable of supplying the required emergency loads.

Each 4160V emergency bus supplies power to the 4kV motors, 600V load centers and motor control centers (MCCs), 575V motors and loads, and the 120V A.C. distribution and lighting transformer. The breaker control cir-cuits for the 4160V switchgear and the 600V load centers are supplied by the station batteries and are independent of grid voltage. The MCC control circuits recieve their control power from individual control power transformers. ,

~ PASNY has verified that one reserve service station transformer cannot supp1y loads'to'both l afely~tMains. ~ - ~ ~ ' ~

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PASNY supplied the equipment operating ranges identified in Table 1.3,7 4.0 ANALYSIS DESCRIPTION 4.1 Design / Operation Changes. The voltages shown on. Table 1 are based on the following licensee proposed changes:

Sk PASNY proposes to lower the taps on the 600V emergency load center transformers to the 3,950/600V tap to optimize emergency bus voltage pro-files. With the transformers normally loaded, the voltage on the 600V emergency load center buses would be 580V (96.6%) and 566 V (94.3%) with a 115kV bus voltage of 117kV and 115kV, respectively.

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, EDGA EDGC t EDGB EDGD i) 1) 1) L) 6COV EM' ERG 6CdY EMERG 600V EMLRG 60DV EMERG BUS 11500 EUS L2.500 BUS 11600 BUS 12600 Figure 1. James A. FitzPatrick unit single-line diagram.

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" [' TA3LE 1 CLASS 1E EQUIPMENT VOLTAGE RATINGS AND '

, ANALYZED WORST CASE TERMINAL VOLTAGES '

(% of nominal voltage)

Maximum

• Min imum" Analyzed i

Equipment Condition Rated Analyzed Rated Steady State Transient 40007 Motors Start -- --

75 --

/ 83.35 Operate 110 105.8 " 90 / 93.32 --

575V Motors Start -- --

, 80 --

80.78 i Operate 110 107.3'# 90 90.08 --

600V Starters Pickup -- --

85 --

82c Dropout -- --

70 --

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Operate 110 .107.5 90 91 --

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a. 115kV nominal: maximum 106.1% and an'alyzed min.aum 100%.

b. "All safety-related electrical, instrumentation, end control equipment required for safe shutdown will o s of90to110percentofnominal."gerateproperlywithinavoltagerange ,

c. All class 1E motors in operation..

. 4.2 Analysis Condicions. PASNY has determined by transient stability analysis that the maximum expected 115kV offsite grid voltage is 122kV and '

tne minimum is 116kV; however, for conservatism, 115kV minimum voltage was i

used as the low grid voltage in the PASNY analysis, I

PASNY has analyzed each offsite source to the onsite distribution

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t system under extremes of load and offsite voltage conditions to determine

! the terminal voltages to 1E equipment. The worst casefelass 1E equipment l terminal voltages occur under the following conditions:

1. The maximum voltage occurs when the offsite 115kV grid j is at 'its maximum expected value and no load on the ,

reserve station and load center transformers.  !

2. The minimum voltage occurs when the offsite 115kV grid

__ .is at its minimum expected value and with a full load on the r'eserve station and load center transformers.

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3. The worst case transient voltages occur when starting one 3,000 hp condensate booster pump when the offsite grid is at its minimum value and with a full load on the reserve station and load center transforners.

4.3 An31ysis Results. Table 1 shows the projected worst case class IE equipment terminal voltages based on the proposed 600V load center trans-former tap settings. Table 2 shows a comparison of the analyzed yottages with the undervoltage relay setpoints.

4.4 Analysis Verification. PASNY has indicated, in their submittal of July 1, 1980/, that the voltage calculations performed for the JAFNPP will be verified by the field test described below. The test will be scheduled during the late 1980 planned outage and the test results will be submitted within 90 days frem the date of plant startup after the outage.

Cnart recorders cnd other analog / digital instruments will be installed in the switchyard on the 345kV and 115kV systeas, on the 4160V IE and non-1E buses (the 1E buses will be 10500 and 10600), and on the 600V emergency load centers and motor control center. The exact location of the test instruments on the 600V system has not yet been determined. However, all 600V IE butes will be monitored d2 ring the test.

The data will be gathered under plant operating conditions, including startup after refueling, for an extended period of time. The loading on the 1E buses will vary with plant operating conditions; however, the data used to verify the analysis will be'for bus'lonos greater than'30%.

The measured bus voltage and loads w!.11 be carrelated with the t_sasured ,

offsite grid voltage to establish the actual distribution system impedance i values. These values will then be compared with the impedance values used in the calculations to verify the accuracy of the analysis is within accept-able tolerances. i 5.0 EVALUATION Six review positions have been established from the NRC analysis guide- ,

lineal and the documents listed in Section 2.0 of this report. Each review pesition is stated below followed by an evaluation of the licensee submittals. The evaluations are based on completion of changes described in Section 4.1.

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

PASNY has shown, by analysis, that the offsite source and distribution system connection combiniation has sufficient capability and capacity for starting and continuously operating the class 1E loada within the equipment voltage ratings (Table 1).

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[ TMM 2 COMPARISON OF ANALYZED VOLTAGES AND UNDERVOLTAGE RELAY SETPOINTS (I of nominal voltage)

Minimum Analyzed" Relay Setpoint Lacation/ Relays Voltage Time Voltage (Tolerance) Time 4160V bus Degraded grid 90.5 continuous 89.5 10 see Loss of grid 80.9b c 71.5/ 2.5 see

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

b. Calculated from Figure 2A and 2B of Reference 7 and Figure 2 of Refer-ence 3. It is the transient voltage due to the start of a condensate booster pump under full load conditions and minimum grid voltage.

c. Transient recovery time not provided but PASNY expects it to be less than 10 sec.8 Position 2--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.

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

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.

Position 4--The NRC letterl requires that test results verify the accuracy of the voltage analyses supplied.

PASNY states that they will supply test results within 90 days from the date of plant startup af ter the late 1980 outage. The proposed test has been described in Section 4.4 of this report and is acceptable.

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).

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PASNY has analyzed the onsite 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 i one unit and an orderly shutdown and cooldown in the remaining units.

This applies to multi-unit plants. It does not apply to the James A. FitzPatrick single-unit station.

6.0 CONCLUSION

S The voltage analyses submitted by PASNY for the James A. FitzPatrick Nuclear Power Station were evaluated in Section 5.0 of this report. Upon the completion of changes described in Section 4.1, it was found that:

1. Voltages within the operating limits of the class 1E equipment are supplied for all projected combinations of plant load and offsite power grid conditions.

2. The proposed test will verify the analysis accuracy.

3. PASNY has determined that no potential for either a rimultanous or consequential loss of both offsite power sources exists. ,

4. Loss of offsite power to class 1E buses, due to spur-ious operation of voltage protection relays, will not occur with the offsite grid voltage within its expected limits.

7.0 REFERENCES

1. NRC letter, William Caamill, to All Power Reactor Licensees (Except Humboldt Bay), " Adequacy of Station Electric Distribution Systems Voltage," August 8, 1979.

2. PASNY letter, Paul J. Early, to Director of Nuclear Regulation, dated September 7, 1979.

3. PASNY letter, G. T. Berry, to Director of Nuclear Regulation, dated October 18, 1976,

4. PASNY letter, G. T. Berry, to Director of Nuclear Regulation, dated December 31, 1976.

5. PASNY letter, G. T. Berry, to Director of Nuclear Regulation, dated July 13, 1977.

6. PASNY letter, G. T. Berry, to Director of Nuclear Regulation, dated October 17, 1977.

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.i 7. PASNY letter, J. P. Boyne, to Director of Nuclear Regulation,. dated

July 1, 1980 i 8. Telecon', D. A. Weber, EGE Idaho, Inc., S. Shultz, PASNY, ,

September 12, 1980. j

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