ML20041C380
| ML20041C380 | |
| Person / Time | |
|---|---|
| Site: | Big Rock Point File:Consumers Energy icon.png |
| Issue date: | 01/31/1982 |
| From: | Farmer F, Roberts E EG&G, INC. |
| To: | Scholl R Office of Nuclear Reactor Regulation |
| Shared Package | |
| ML20041C379 | List: |
| References | |
| CON-FIN-A-6425-1, TASK-06-07.C1, TASK-6-7.C1, TASK-RR EGG-EA-5755, NUDOCS 8203010251 | |
| Download: ML20041C380 (9) | |
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1 EGG-EA-5755 JANUARY 1982 i
l SYSTEMATIC EVALUATION PROGRAM, TOPIC VI-7.C.1, INDEPENDENCE OF REDUNDANT ONSITE POWER SYSTEMS, BIG ROCK POINT i
l E. W. Roberts F. G. Farmer 0
U.S. Department of Energy Idaho Operations Office
- Idaho National Engineering Laboratory L
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This is an informal report intended for t.se as a preliminary or working document Prepared for the U.S. Nuclear Regulatory Commission Under DOE Contract No. DE-AC07-761001570 g
FIN No. A6425-1 g g g g,,,3, t 8203010251 820222 p PDR ADOCK 05000155 t P PDR
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FORW EG&G 390 f;ew 1944 INTERIM REPORT Accession No.
Report No. EGG-EA-5755 Contract Program or Project
Title:
Electrical, Instrumentation, and Control Systems Support for the Systematic Evaluation Program (II)
Subject of this Document:
. Systematic Evaluation Program, Top c V
.., Independence of i
I7C1 Redundant Onsite Power Systems, Big Rock Point Type of Document:
Informal Report 2
Author (s):
E. W. Roberts F. G. Farmer Date of Document:
January 1982 Responsible NRCIDOE Individual and NRCIDOE Office or Division:
R. F. Scholl, Division of Licensing, NRC 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
-s Washington, D.C.
Under DOE Contract No. DE-AC07 761D01570 l
NRC FIN No.
A6425-1
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INTERIM REPORT I
i
0038J SYSTEMATIC EVALUATION PROGRAM
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TOPIC VI-7.C.1 INDEPENDENCE OF REDUNDANT ONSITE POWER SYSTEMS BIG ROCK POINT Docket No. 50-155 January 1982 E. W. Roberts F.'G. Farmer EG&G Idaho, Inc.
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ABSTRACT This SEP Technical Evaluation, for Big Rock Point, reviews the electrical independence between redundant standby (onsite) power sources and their distribution systems.
5 FOREWORD This report is supplied 'as part of the " Electrical, 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.
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. CONTENTS
1.0 INTRODUCTION
I 2.0 CRITERIA........................'................................
1 3.0 DISCUSSION AND EVALUATION.......................................
1 3.1 AC Supplies...............................................
I 3.2 DC Supplies...............................................
2 4.0
SUMMARY
3
5.0 REFERENCES
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SYSTEMATIC EVALUATION PROGRAM TOPIC VI-7.C.1 INDEPENDENCE OF REDUNDANT ONSITE POWER SYSTEMS BIG ROCK POINT i.0 INTRODUCTION The objective of this reveiw is to determine if the onsite electrical poker systems (AC and DC) are in compliance with current licensing criteria for electrical indspendence between redundant standby (onsite) power sources and their distribution systems.
General Design Criterion 17 requires that the onsite electrical power supplies and their onsite distribution systems shall have sufficien inde-pendence to perform their safety function assuming a single failure
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Regulatory Guide 1.6, " Independence Between Redundant Standby (Onsite)
Power S3urces and Betwee'n Their Distribution System," and IEEE Stan-dard 308-1974, "IEEE Standard Criteria for Class lE Power Systems for Nuclear Power Generating Stations," provide a basis acceptable to the NRC staff for meetin powersystems.5,gGDC17inregardstoelectricalindependenceofonsite
'e 2.0 CRITERI A When operating from standby sources, redundant load groups and redun-dant 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 group under accident conditions
-(2) No provisions should exist for automatically transferring one load, coup to anotter load group or loads between redundant power sources (3)
If means exist for manually connecting redundant load groups together, at least one interlock should be provided to prevent an operator error that would parallel their standby power sources (4)
Each DC load group should be energized by a battery and battery charger.
The battery-charger combination'should have no auto-matic connection to any other redundant DC load group.
3.0 DISCUSSION Ala EVALUATION 3.1 AC Supplies 3.1 l Discussion.
In the Commission Memorandum and Order, dated May 26,1976, g Big Rock Point (BRP) was granted a lifetime exemption from the single failure requirements of 10 CRF Part 50.46 and Appendix K, Para-graph I.D.1 as applied to a LOCA caused by a break in a core spray line and 1
y a concurrent single failure in the remaini'ng core spray system.
Included in the order was a plant-life exemption from the. requirement that the ECCS short-term and long-term cooling functions be invulnerable to a single failure which disables onsite power assuming offsite power is available.
This was allowed in view of the high avai-lability of offsite power at BRP, together with improved reliability of the onsite diesel and guaranteed availability of a backup diesel for long-term cooling. The Director's comments note that, in view of the small size of this plant compared with the system capacity, trips of the plant due to internal causes are rela-tively unlikely to cause a loss of offsite power.
As a result of the above action, BRP. has only one onsite diesel gener-ator unit.
The independence between the single onsite AC power source and the off-site sources is considered in this review. With offsite power available, the safety bus, motor control center (MCCC)2B, is supplied power from plant 480 V MCC2A. Plant 480 V MCCI A is an alternate feed to MCC28. With loss of offsite power, both tie breakers between the safety bus and plant buses
,are automatically opened when the diesel generator output reaches 440 volts (92% of rated output).
Interlocks prevent the connection of the diesel generator unit to the safety bus if either of the tie breakers are not open.
Plant procedures are that MCCIA and/or 2A are to be connected to the safety bus when utilizing the diesel generator supply. The procedure.to manually connect the plant buses to the safety bus require the following actions:
(1) Open the incoming offsite supply breakers to bus MCCIA and/or 2A (2) Remove most loads from the plant bus (MCClA or 2A)
(3) Close appropriate tie breaker between MCClA and/o.r 2A and MCC28 (4) Sequentially load ess'ential plant equipment (manually).
Interlocks prevent the paralleling of the diesel generator unit with the offsite power sources by preventing closure of the necessary supply breakers to MCCIA and 2A if the uiesel generator is connected to the plant bus.
There is no automatic transfer of loads or load groups etween the ons.ite and offsite power supplies.
3.1.2 Evaluation. The onsite and offsite AC power supplies have sufficient inde,pendence since there is no automatic transfer of loads between sources and the manual ties have interlocks to prevent paralleling of power sources.
3.2 DC Supplies 3.2.1 Discussion. B'3 Rock Point Nuclear Station has a single station 125 V DC battery-charger set to supply the plant loads and a por-tion of the safety requirements. This battery charger is actually two 2
ke chargers operated in parallel.8 In addi' tion to the station battery-charger set, there are four uninterruptable power supplies (UPS), each consisting of a battery, battery-charger, and an inverter. Each UPS has outputs for 120 V AC and 125 V DC loads. The diesel fire water pump and the diesel generator have their own battery-charger sets for starting power. The diesel fire water pump battery-charger set also supplies its own control power.
On February 27, 1976, Consumers Power Company (CPCo) provided th a " Report on Evaluation of Adequacy of Emergency Core Cooling System"y NRC Included in this report was a single failure analysis of the effects on ECCS with the loss of the single battery-charger set.
It was determined that the failure of the station battery-charger set, with loss of offsite power, would disable the ECCS. This would be due to (a) the loss of 125 V DC power to operate the nozzle spray valves and (b) the disabling of the single onsite AC power supply and, therefore, prevention of the operation of the redundant 480 V AC operating valves.
Subsequent to the analysis, to cor-rect the single f ailures, control power for the diesel generator tie breaker and the two plant-to-safety bus tie breakers was removed from the station 125 V DC battery set and placed on the UPS "A" 125 V DC souice.
Control power for the diesel generator is supplied by its own battery-charger set.8 3.2.2 Evaluation. Each DC load group has its own battery-charger set and, therefore, no manual or automatic transfers betwee.n battery-charger load groups.
4.0
SUMMARY
A review of drawings and docketed information indicate that the AC and DC power supplies meet the current licensing criteria for independence of redundant power sources, subject to the exemptions previously granted.
Future SEP actions under Topic VI-7.C.2, " Failure Mode Analysis ECCS;"
Topic VII-3, " Systems Required for Safe Shutdown;" and Topic VIII-1.A,
" Pot.ential Equipment Failures Associated with Degraded Grid Voltage," will review the capabilities of the onsite power systems to meet safety require-ments.
5.0 REFERENCES
1.
Letter CPCo (R. B. Sewell) to NRC (S. J. Chilk) dated 'Fe'bruary 27, 1976, attached report, " Report on Evaluation of Adequacy of Emergency Core Cooling System."
2.
Memo to S. J. Chilk from B. C. Rusche, dated April 19, 1976, " Staff Views Regarding Consumers Power Company Report on Evaluation of Adequacy of Emergency Core Cooling System for Big Rock Point,"
pages 15 through 20.
3.
Memorandum and Order by the Commissioners, NRC, in the matter of CPCo, Big Rock Point, dated May 26, 1976, page 9.
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General Design Criterion 17,." Electric Pbwer System," of Appendix A,
" General Design Criteria for Nuclear Power Plants," to 10 CFR Part 50,
" Domestic Licensing of Production and Utilization Facilities."
5.
" Independence Between Redundant Standby (Onsite) Power Sources and
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Between Their Distribution Systems," Regulatory Guide 1.6.
l 6.
"IEEE Standard Criteria for Class IE Power Systems for Nuclear Power Generating Stations," IEEE Standard 308-1974, The Institute of Electrical and Electronic Engineers,- Inc.
7.
Consumers Power Company Drawings:
WD740, Sht 1, Revision M, dated 3/29/78 WD740, Sht 11, Revision M, dated 6/10/77 WD740, Sht 12, Revision J, dated 10/15/76 WD740, Sht 13, Revision L, dated 4/18/78 0740G 30101, Revision S, dated 4/18/78 0740G 30102, Revision M, dated 4/28/77 0740G 30105, Revision K, dated 7/28/77 0740G 301001, Revision B, dated 7/14/76 8.
Letter, CPCo (Vincent) to NRR (Crutchfield), dated December 9, 1981.
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