ML20039A684

SEP Topic VI-7.C.1,Independence of Redundant Onsite Power Sys,Re Ginna Nuclear Station, Informal Rept

ML20039A684
Person / Time
Site:	Ginna
Issue date:	11/30/1981
From:	Mays S, Vanderbeek R EG&G, INC.
To:	Scholl R Office of Nuclear Reactor Regulation
References
CON-FIN-A-6425-1, TASK-06-07.C1, TASK-6-7.C1, TASK-RR EGG-EA-5641, NUDOCS 8112210142
Download: ML20039A684 (8)

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N - A , ~ ~ .w3h$  ? Nks WWh - This is an informal report intended for use as a preliminary or working document ad Prepared for the U.S. Regulatory Commission sUnder DOE Contract No. DE-AC07-761001570 FIN No. A6425 -l

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p E G n B -. ..,- j roau ccao u i (Rev 1179) INTERIM REPORT Accession No. Report No. EGG-EA-5641

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Title:

Electrical, Instrumentation, and Control Systems Support for the Systematic Evaluation Program (III) Subject of this Document: Systematic Evaluation Program, Topic VI-7.C.1, Independence of Redundant Onsite Power Systems, R. E. Ginna Nuclear Station Type of Document: Informal Report Author (s): S. E. Mays Revised by R. VanderBeek Date of Document: November 1981 Responsible NRC Individual and NRC Office or Division: Ray F. Scholl, Jr., 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 Washington, D.C. Under DOE Contract No. DE-AC07-761D01570

   ,                                                 NRC FIN No. A6425-1 INTERIM REPORT

l l 0094J SYSTEMATIC EVALUATION PROGRAM TOPIC VI-7.C.1 INDEPENDENCE OF REDUNDANT Ol: SITE POWER SYSTEMS R. E. GINNA NUCLEAR STATION Docket No. 50-244 November 1981 S. E. Mays Revised by R. Vanderbeek EG&G Idaho, Inc. 11-5-81 i l

n ABSTRACT i .. This SEP Technical Evaluation, for the R. E. Ginna Nuclear Station, reviews the electrical independence between redundant standby (onsite)- power sources and their distribution systems. FOREWORD This_ report is supplied as part of the "ElectricaI, Instrumentation,.

           - and Control. Systems Support for the Systematic Evaluation Program (II) being conducted for the U.S. Nuclear Regulatory Commission, Office of
           ' Nuclear Reactor Regulation, Division of Licensing by EG&G Idaho, Inc.,

Reliability & Statistics Branch. The U.S. Nuclear Regulatory Commission funded the work under the authorization B&R 20-10-02-05,' FIN A6425-1. e l l W ii 1

i l I CONTENTS  : 1.0 I NTR O D UC T I O N . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1 2.0 CRITERIA ........................................................ 1 2.1 AC Supplies ............................................... 1 2.2 DC Supplies ............................................... 1 3.0 OISCUSSION AND EVALVATION ....................................... 2 3.1 AC Supplies ............................................... 2 3.2 DC Supplies ............................................... 2 4.0

SUMMARY

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5.0 REFERENCES

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e S e e a 111

l I SYSTEMATIC EVALUATION PROGRAM TOPIC'VI-7.C.1 INDEPENDENCE OF REDUNDANT ONSITE POWER SYSTEMS FINAL DRAFT R. E. GINNA NUCLEAR STATION

1.0 INTRODUCTION

The objective of this review is to determine if the onsite electrical l power systems (AC and DC) are in compliance with current licensing criteria l for electrical indepen:. ",e between redundant standby (onsite) power sources I and their distribution systems. General Design Criterion 17 requires that the onsite electrical power supplies and their onsite distribution systems shall have sufficient inde-pendence to perform their safety function assuming a single failure. Regulatory Guide 1.6, " Independence Between Redundant Standby (0nsite) Power Sources and Between Their Distribution Systems," and IEEE Stan-

            -dard 308-1974, "IEEE Standard Criteria for Nuclear Power Generating Sta-tions" provide a basis acceptable to the NRC staff for meeting GDC 17 in regards to electrical independence of onsite power systems.

2.0 CRITERIA

 .                 2.1 AC Supplies. Regulatory Guide 1.6 Section D.4 states that when operating from standby sources, redundant load groups and redundant standby sources should be independent of each other at least to the following extent.

1. The standby source of one load group should not be automatically paralleled with the standby source of another load group under accident conditions

2. No provisions should exist for automatically trans-ferring one load group to another load group or loads between redundant power sources

3. If means exist for manually connecting redundant load groups together, at least one interlock should beprovidedtopreventanoperatorergorthatwould parallel their standby power sources 2.2 DC Supplies. As stated in Regulatory Guide 1.6, Section D.3, each d-c load group should be energized by a battery and battery charger.

The battery-charger combination should have no automatic connection to any l - other redundant d-c load group, t r I 1 i L _- _ _ _ _ _ _ . - . _ _ . -_ - _ _ - - . -- - --. -- - - . --- ---

3.0 DISCUSSION AND EVALUATION 3.1 AC Supplies Discussion. The Ginna onsite emergency AC power system consists of two redundant diesel-generator power trains. Diesel generator lA (DGlA) supplies 480 V buses 14 and 18 while diesel generator 1B (DGlB) supplies buses 16 and 17.

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Manual means exist to tie buses 17 and 18 through a tie breaker and to tie buses 14 and 16 through a tie breaker. The control circuit for each - breaker provides interlocks such that the breaker cannot be shut if either DG is closed on either bus or if the normal feeders to the bus are closed. Additionally, if the tie breakers are closed, they will trip open upon restoration ~of normal power, DG closing on the bus, or any safety injection signal. Means ex st to power safety injection pump SI-lC from either bus 14 or i

16. The control circuit for the breaker from each bus is designed such that shutting of one breaker prevents shutting the other breaker so that paralleling the redundant DGs is prevented.

Instrument buses lA,1B, IC, and ID are capable of being supplied by multiple sources. Each bus is supplied by a pair of mechanically inter-locked breakers such that paralleling of redundant sources is prevented. Evaluation. The redundant onsite AC power trains have no automatic transfers of loads and/or load groups. The manual transfer of load groups or manual interconnection of emergency buses have the required interlocks . to prevent inadvertent paralleling of redundant sources. Therefore, the onsite emergency AC system is in compliance with current licensing criteria for independence of onsite power systems. ' 3.2 DC Systems Discussion. Ginna Nuclear Station has two redundant battery and charger trTins to supply 125 V DC emergency loads. Each train consists of a battery, a 75-amp charger, and a 150-amp charger. Means exist to interconnect both trains by manually shutting a tie breaker. This breaker is padlocked open and the key is maintained by the shift foreman. Current operating procedures require removal of the feeder i i fusefrgmoneofthebusesfeedingthetiebreakerpriortoclosingthetie breaker . However, no interlocks exist to prevent closure of the tie l breaker if the feeder fuse has not been removed. This would allow par-alleling of the redundant DC trains. Automatic transfer of 125 V DC load groups from train A to B (or vice l versa) occurs in seven locations. Control power for 480 V switchgear on l buses 14, 16, 17, and 18, DGlA control panel, DGlB control panel, and the

• l rod drive MG set control panel automatically transfer to the redundant train on a loss of power from the normal source. Each load will automati- .

cally transfer back to the normal supply when it is regained. 1 2

l. L Evaluation. The_125 V DC. system has one manual tie between redundant j trains and seven automatic transfers of power from one redundant train to

the other.

Although administrative controls _are provided to prevent par-l alleling redundant trains via the tie breaker, no physical-or electrical

       . interlocks exist to. prevent parallel operation of the two trains. There-fore, the.125 V DC system is not in compliance with' Regulatory Guide .l.6 Section 0.4.C for current licensing criteria with respect to independence l       of onsite-power systems.

4.0

SUMMARY

   '*        'The review of docketed information and plant electrical drawings indi-cate that the Ginna Nuclear Station 'onsite AC redundant power sources and

distribution system meet the current licensing criteria for independence of l onsite power systems. The 125 V DC system has seven automatically trans-ferred loads and

one manual tie breaker which are not in compliance with current criteria for independence of onsite power systems.

5.0 REFERENCES

1. General Design Criterion 17, " Electrical Power System," of Appendix A,

              " General Design Criteria of. Nuclear Pcwer Plants," to 10 CFR Part 50,
              " Domestic Licensing of Production and Utilization Facilities."

2. " Independence Between Redundant Standby (Onsite) Power Sources and Between Their Distribution Systems," Regulatory Guide 1.6.

3. -Rochester Gas and Electric Corp. letter (White) to NRC (Ziemann) dated i . April 18, 1979.

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4. RG&E Corp. drawings ~ 10905-59, 62, 63, 74, and 75.

5. RG&E Corp. drawings 21489-269, 33013-652 and 33013-756.

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