ML20003C153

Technical Evaluation Rept,Adequacy of Station Electric Distribution Sys Voltages,Ja Fitzpatrick Nuclear Power Station, Preliminary Rept

ML20003C153
Person / Time
Site:	FitzPatrick
Issue date:	01/31/1981
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-5340, NUDOCS 8102260716
Download: ML20003C153 (13)

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Wbd i EGG-EA-5340 January 1981 TECHNICAL EVALUATION REPORT. ADEQUACY OF STATION

. ELECTRIC DISTRIBUTION SYSTEM VOLTAGES, JAMES A. FITZPATRICK NUCLEAR POWER STATION, i DOCKET NO. 50-333

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U.S. Department of Energy Idaho Operations Office

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- This is an informal report intended for use as a preliminary or working document Prepared for the U.S. Nuclear Regulatory Commission

'Under DOE Contract No. DE-AC07-761D01570

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<n., um INTERIM REPORT Accession No.

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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):

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NRC Researc1 anc Tecinical Date of Document: SSistance ep0TI 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.

EG&G Idaho, Inc.

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

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A ADEQUACY OF STATION ELECTRIC DISIRIBUTION SYSTEM VOLTAGES JAMES A. FITZPATRICK NUCLEAR POWER STATION Docket No. 50-333 January 1981 i . .

D. A. Weber Reliability and Statistics Branch Engineering Analysis Division EG&G Idaho, Inc.

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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 reviews the submittals for the James A. FitzPatrick Nuclear Power Statier.

The offsite power sources, in conjunction with the onsite distribution system, have been shown to have suf ficient 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, aad Control Systems (EICS) issues program being conducted for the .

U.S. Nuclear Regulatory Commission, Office 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-orizction entitled " Electrical, Instrumentation, and Control System.Sup-port," B&R 20 19 01 03, FIN No. A6256.

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.i CONTENTS

1.0 INTRODUCTION

...................................................... 1 2.0 D ES IGN B AS I S C RI TE 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 . REF E REN C E S . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 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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NRC Researci anc, , .ecanica Assistance Report ADEQUACY OF STATION ELECTRIC DISTRIBUTION SYSTEM VOLTACES JAMES A. FITZPATRICK NUCLEAR POWER STATION 1.0 IlfrRODUCTION 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 1E loads. Tais 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 the of fsite power ' system, to maintain'the voltage for the required class 1E 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 1E equipment are derived from the following:

1. General Design Criterion 17 (GDC 17), " Electrical Power Systems,". of Appendix A, " General Design Criteria for Nuclear Power Plants," of 10 CFR 50. 8

2. General Design Criterion-5 (CDC 5), " Sharing of struc-tures,' Systems, 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 Control,"'of' Appendix A, " General Design Criteria for Nuclear Power Plants," of 10 CFR 50..

'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 statior 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, independent 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.-

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! PASNY has verified that one reserve service station transformer cannot supply loads to both safety trains. >

i l PASNY supplied the equipment operating ranges identified in

! Table 1.3,7 L

4.0 ANALYSIS DESCRIPTION 4.1 Design / Operation Changes. The voltages shown on Table 1 are ,

based on the following licensee proposed changen:

PASNY proposes to~1ower 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 lof 117kV and 115kV, respectively.

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

(% of nominal voltage) .

Maximum" Minimum" Analyzed Equipment Condition Rated Analyzed Rated Steady State Transient 4000V Motors Start -- --

75 --

83.35 operate 110 105.8 90 93.32 --

575V Motors Start -- --

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80.78 Operate 110 107.3 90 90.08 --

600V Starters Pickup -- --

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62C Dropout -- --

70 --

82 Operate 110 107.5 90 91 --

Other Equipmenth

a. 115kV nominal: maximum 106.1% and analyzed minimum 100%. .

b. '"All safety-related electrical, instrumentation, and control equipment required for safe shutdown will o erate properly within a voltage range of 90 to 110 percent of nominal."

c. All class IE motors in operation.

4.2 Analysis Conditions. 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, ll5kV minimum voltage was

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used as the low grid voltage in the PASNY analysis.

PASNY_has analyzed each offsite source to the onsite distribution 2

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

the. terminal voltages to IE equipment. The worst case class lE equipment terminal voltages occur under theLfo11owing conditions:

1. 'The maximum voltage occurs when the offsite 115kV grid 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 reserve 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 transformers.

4.3 Analysis Results. Table 1 shows the projected worst case class lE

, equipment terminal voltages based on the proposed 600V load center trans-former tap settings. Table 2 shows a comparison of the analyzed voltages 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 from the date of plant startup af ter the outage.

Cnart recorders and other analog / digital instruments will be installed in the switchyard on the 345kV and 115kV systems, on the 4160V IE and non-lE buses (the lE 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 buses will be monitored during the test.

. The data will be gathered under plant operating conditions, including startup af ter refueling, for an extended period of time. The loading on the lE buses will vary with plant operating conditions; however, the data used -to verify the analysis ~ will be for bus loads greater than 30%.

The= measured bus voltage and loads will-be correlated with the measured offsite grid voltage to establish the actual distribution system impedance values. These values will then'be compared witn the impedance values used in the calculations to verify the accuracy of the analysis is within accept-aule tolerances.

5.0 EVALUATION Six review positions have been established from the NRC analysis guide- I linesi and the documents lieted in Section 2.0 of this report. Each review position is stated below followed by an evaluation of the licensee submittals. The evaluations are based on completioa 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 operating all

,_ class IE 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'lE loads within the equipment voltagc ratings (Table 1).

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TABLE 2 COMPARISON OF ANALYZED VOLTAGES AND UNDERVOLTAGE RELAY SETPOINTS

(% of nominal voltage) ,

Minimum Analyzed" Relay Setpoint Location / 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 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.

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.

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c. Transient recovery time not provided but PASNY expects it to be less .

than 10 sec.8 Position -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 IE distribution systems due to operation of voltage protection relays, must not' occur when the offsite power source is within expected voltage limits.

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As shown in Table 2, voltage relays will not cause loss of class lE distribution systems when the offsite grid voltage is within expected volt-age limits.  !

Position 4--The NRC letter 1 requires that test results verify the accuracy of the voltage analyses supplied.

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PASNY states that they will supply test results within 90 days from the'date of plant st'artup after-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

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consequential loss of both required circuits from the offsite power network

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.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 CDC 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 1E loads with an accident in 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 of fsite power grid conditions.

2. The proposed test will verify the analysis accuracy.

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

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

7.0 REFERENCES

1. NRC letter, William Cammill, to All Power Reactor Licensees (Except Humboldt Bay), " Adequacy of Station Electric Distribution Systems Voltage," Auguat 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 Oc tober 18, 1976.

4. PASNY letter, G. T.-Berry, to Director of Nuclear Regulation, dated

-December 31, 1976.

-5. PASNY letter, G. T. Berry, to. Direct r of Nuclear Regulation, dated

, July 13, 1977.

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

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7. PASNY letter, J. P. Boyne, to Director of Nuclear Regulation, dated July 1, 1980

8. Telecon, D. A. Weber, EG&G Idaho, Inc., S. Shultz, PASNY, September 12, 1980.

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