ML20039A384

Safety Evaluation Rept Re Adequacy of Station Electric Distribution Sys Voltages.Concurs W/Eg&G Technical evaluation,EGG-EA-5433

ML20039A384
Person / Time
Site:	Big Rock Point File:Consumers Energy icon.png
Issue date:	11/30/1981
From:	Office of Nuclear Reactor Regulation
To:
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ML20039A380	List: ML20039A379 ML20039A384
References
NUDOCS 8112170472
Download: ML20039A384 (4)

Text

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ENCLOSURE 1 J

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NUCLEAR REGULATORY COMMISSION 5 \\

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SAFETY EVALUATION REPORT 1

BIG ROCK POINT PLANT DOCKET NOS.

50-155 ADEQUACY OF STATION ELECTRIC DISTRIBUTION SYSTEM VOLTAGES i:

INTRODUCTION AND

SUMMARY

C~onsumers Power Company (CPCo) was requested by NRC letter. dated August 8, 1979 to review the electric power system at Big Rock Point Plant. The f

review w'as to consist of:-

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' a)

Determining analytically ~the capacity of tiie offsite power system and the onsite distribution system to start automatically and to ' '

operate all required loads within their required voltage rating in

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the event of 1) an anticipated transien't, or 2) an accident (such as LOCA)without manual shedding of any electric loads.

c)

Determining if there are any events or conditions which could result in the simultaneous or consequential loss of both requised,c.ircuits.

f r ;.T.he effsite ne:..crk ::

re ensite electric distrib:icn sys' tem thus violating the requirements of GDC 17.

The August 8,1979 letteiincluded staff guidelines for performing the, required voltage analysis. The licensee was further required'to perform a test in order to verify the validity of the analytical results.

CPCo's responses consisted of voltage analyses and responses to staff questions dated February 19, 1980; A.ugust. 29,1980; March 23,1981; May 4,1981; and Other CPCo correspondence dated June 14,19f8;. August 21, August 26, 1981.

1980; and December 12, 1980 were also reviewed for this report.

Proposed.

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Technical Specifications were received with a letter dated October 27, 1981.

A detailed review and technical evaluation of the submittals were performed

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by EG&G under centract to the NRC and with general supervision'by the NRC staff. This work is reported by EG&G in +.he attached Technical Evaluation 1

l Report dated September 1981 and entitled:

" Adequacy of Station Electric Distribution System Voltages, Big. Rock Point Plant." We have reviewed this report and concur in the conclusions that the onsite distribution system in conjunction with the.offsite power source are capable of'providing acceptable voltages _ to the Class lE equipment under worst case station

. electric loads and expected grid voltage limits.

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EVALUATION CRITERIA The criteria used by EG&G in this technical evaluation of the an'alysis.

includes GDC 5 (" Sharing of Structures, Systems, and Components"),

4 GDC 13 (" Instrumentation and Control"), GDC 17 (" Electric Power Systeps")

of Appendix A to 10 CFR 50; IEEE Standahd 308-1974 (" Class lE Power Sjstems for Nucisar Power Generating Stcticns"), ANSI CS4.1-1977

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(" Voltage Ratings for Electric Power Systems and Equipment - 60Hz"); and the staff positions and guidelines in NRC letter to CPCo dated August 8,1979.

CECO has analyzed each offsite source to the onsite distribution system i

i under extremes of load and offsite voltage conditions to determine the terminal volta ~ges'to lE equipment. The. worst case Class 1E equipment i

terminal voltages occur under the following conditions:

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The qinimum expected continuous load terminal voltage for a Class lE.

load occur.s when either the unit generator voltage is at its minimum ~

with full-unit loads or the 46kV grid is at its minimum with normal unit loads.

2.

The minimum expected transient load terminal voltage for a Class 1E load occurs when the 138k'V grid is at its minimum, normal unit loads are running and the 1500 hp reactor feed ppmp is started.

3.

The maximum expected continuous load terminal voltage for a Class 1E load occurs when the unit generator voltage is at;its maximum 7

value and t.he unit loads are at a minimum.

The ccmputer analysis used by CPCo was verified by taking actual voltage measurements with an oscillograph and comparing these measurements with the corresponding calculated values.

For both prestart and start-up conditions, the error was not greater than 1.8'4 which is within the accuracy of the measuring instruments. The staff finds this acceptable.

CONCLUSIONS We have reviewed the EG&G Technical Evaluation Report and concur in their findings that:

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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.

2.

CPCo's test has verified the accuracy of their analysis.

3.

CPCo had determined that 'there is no potential for either a simultaneous or a consequential loss of both offsite power sources.

However, there are portions of the Big Rock Point distribution system where a single component failure can disable both sources.

j This condition exists because Big Rock Point was licensed prior to the promulgation of 10 CFR 50, Appendix A,. " General Design Criteria for Nuclear Power Plants," specifically GDC 17. The' portions of the offsite power system in non-compliance with GDC 17 will be examined as part of Topic VII-3 of the Systematic Evaluation Program.

Dated: November 30, 1981 _.

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ENCLOSURE 2 EGG-EA-5433 SEPTEMBER 1981 ADEQUACY OF STATION ELECTRIC DISTRIBUTION SYSTEM

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VOLTAGES, BIG ROCK POINT PLANT, D0.CKET NO. 50-155, 3

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U.S. Nuclear Regulatory Corm:ission

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Under DOE Contract No. DE-AC07-76ID01570 Q

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E Idshe. Int FC#W E!&G.3ee w ii.m INTERIM REPORT Accession No.

, Report $o. EGG-EA-543's C:ntr ct Program or Project

Title:

Selected Operating Reactor Issues Program (III)

Subj:ct of this Document:

Adequacy of Station Electric Distribution System Voltages, Big Rock Point Plant, Docket No. 50.155, TAC No.12781 Type cf Document:

Informal Report Authur(s):

A. C. Udy D-tm cf Document:

September 1981 Responsible NRC Individual and NRC Office or Division:

S. S. Bajwa, Division of Licensing This document was prepared primarily for preliminary orinternat use. it has not received

'.;l! revieiv ard accrova! Since there may be substantive changes,this document should not be considered final.

EG&G Idaho. Inc.

Idaho Falls, Idaho 83415 6

Prepared for the U.S. Nuclear Regulatory Commission Washington, D.C.

Under DOE Contract No. DE AC07 761D01570 NRC FIN No.

A6429 INTERIM REPORT 1

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ADEQUACY OF STATION ELECTRIC DISTRIBUTION SYSTEM VOLTAGES SIG ROCK POINT PLANT Docket No. 50-155 s

September,1981

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A'. C. Udy Reliability and Statistics Branch Engineering Analysis Division EG&G Idano, Inc.

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Oraft 9-18-81 TAC'No. 12781 I

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4 ABSTRACT The Nuclear Regulatory Commission has required all licensees to analyze the electric power system at each' nuclear station. This re' view is to deter-mine if the onsite distribution system in conjunctiun with the offsite pcwer 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 Big Rock Point Plant.

The offsite power sources, in conjunction with the onsite distriDution

- system, has been shown to have sufficient capacity and capability to auto-matically start as well as continuously 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 71is recort is sucolied as cart of the " Selected Goerating Reactor Issues 3rogram (111)" oeing concocted for the J.S. Nuclear Regulatory Commission, Office of Nuclear Reactor Regulation, Division of Licensin'g, by EG&G Idaho, Inc., Reliability and Statistics Branch.

~~e U.S. "uclear Regulatory Cc. mission fundec tne verk under the autnorization, B&R 20 19 01 06, FIN No. A6429.

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9 CONTENTS s

l.0 INTRODUCTION....................................................

. 1 2.0 DESIGN BASIS CRITERIA...........................................

1-3.0 SYSTEM DESCRIPTION..............................................

2 4.0 ANALYSIS DESCRIPTION............................................

2 4.1 An alys i s Cond i t ions.......................................

2 4.2 Analysis Results..........................................

2:

4.3 Analysis Verification.....................................

2 5.0, EVALUATION......................................................

4

6.0 CONCLUSION

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5

7.0 REFERENCES

6 FIGURE

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Big Rock Point electrical single-line diagram...................

3 TABLES 1.

Class lE Equipment Voltage Ratings and An alyzed Worst Case Load Terminal Voltages......................

4 2.

Comoarison of Analyzed Voltages and Uncervoitage Relay Setpcints....................................

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ADEQUACY OF STATION ELECTRIC OISTRIBUTION SYSTEM VOLTAGES BIG ROCK POINT PLANT

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1.0 INTRODUCTION

An event at the Arkansas Nuclear One station o'n September.16,1978 is.

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As a result.of this described in NRC IE Information Notice No. 79-04.

event, station conformance to General Design Criteria (GDC) 17 is being The NRC, in the generic letter questioned at all nuclear power stations.

of Augu{t 8,1979, " Adequacy of. Station Electric Distribution Systems required each licensee to confirm, by analysis, the adequacy ofThis le ages,"

the voltage at the class lE loads.

lines to be followed in determining if the load terminal voltage is adequate.

to start and continuously operate the class lE loads.

Consumers Power Company (CPCo) responded with letters dated Feb'ruary 19, 1930,2 and August. 29, 1980.3 CPCo supplied further information requested for this review on March 23, 1981.4 CPCo correspondence of June 14, 1978,5 August 21, 1980,6 and December 12, 1980,7 were also reviewed for this report. Additignal clarifications were submitted.on May 4,19818 and August 26, 1981.V Based on the information supplied by CPCo, this report addresses the capacity and capability of the onsite distribution system of the. Big Rock Point Plant, in conjunction with the offsite power system, to maintain the voltage for the required' class lE equipment within acceptable limits for the aorst-case starting and load conditions.

2.0 DESIGN BASIS CRITERIA The positions applied in determining the acceptability of the offsite voltage conditiens in supolying power to the class lE equipment are derived fr:m :ne fol'c.ving:

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

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

of 10 CFR 50.

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

tems, and Components," of Appendix A, " General Design Criteria for Nuclear Power Plants," of 10 CFR 50.

General Design Criterion 13 (GDC 13),. " Instrumentation.and Con-3.

trol," of Appendix A. " General Design Criteria for Nuclear Power Plahts," of 10 CFR 50.

1 4.

IEEE Standard 308-1974, " Class lE Power Systems for Nuclear Power Generating Stations."

5.

Staff positions as d ailed in a letter sent to the licensee,

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dated August 8, 1979 99 1

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L Position 2--With the maximum expected offsite grid voltage and minimum load concition, each offsite source and distribution system connection combination must be capable of continuously operating the required class IE equipment without exceeding the equipment voltage ratings.

C'PCo has shown, by analysis, that the voltage ratings of tha class IE '

equipment will not be exceeded.,

o Position 3--Loss of offsite power to either of the redundant class 1E,

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 the loss of the class lE distribution system when the offsite grid voltage is within expected voltage limits. Big Rock Point does not have a redun, dant class lE distribution system.

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

CPCo has verified, by test, the validity of the anaysis for the Big I

Rock Point Plant.

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

• f The Big Rock Point unit does not comply with GDC 17 since it has 'a single 2400V 'ous between redundent offsite grids ts the single'480V class IE distribution system. The NRC will examira tnis fully in tne Sjstematic Evaluation Program, Topic VII-3, Safe 'nutcown.

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 r a :cerating voltage for all required class 1E loads witn an accident in one unit and an orderly _ shutdown anc cooldown in tne remaining units.

This applies to multi-unit plants.

It does not apply to Big Rock Point, a single-unit station.

6.0 CONCLUSION

S The voltage analyses submitted by CPCo for Big Rock Point were evalu-ated in Section 5.0 of this report.

It was found that:

1.

Voltages within the operating limits 'of the class lE equipment a.re supplied for all projected combinations of plant load and offsite power grid conditions.

2.

The test used to verify the analysis shows the analyses to be an accurate representation of the worst case conditions analyzed.

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5.

CPColetter, William.S.Skibitsky,toDirectob,NuclearReactor Regulation, It.lC, "On-site Emergency Power Sou rces," June 14, 1978.

CP'o letter, David P. Hoffman, to Director, Nuclear Reactor Regula -

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C tion, NRC, " Degraded Grid Voltage," August 21, 1930.

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CPCo letter, David P. Hoffman, to Director, Nuclear Reactor Regula.

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tion, NRC, " Response to Request for Additional Information Related to the Generic Issue on Onsite Power Systems," December 12, 1980.

CPCo letter, Gregory C. Withrow to Director, Nuclear Reactor 8.

Regulation, NRC, " Generic Issue--Adequacy of Station Electric Distribution Voltages,"_ May 4,1981.

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CP'Co letter, David P. Hoffman to Director of Nuclear Reactor Regulation, NRC, " Station Electric Distribution System Voltages and Degraded Grid Protection," August 26, 198,1.

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