ML20033C298
| ML20033C298 | |
| Person / Time | |
|---|---|
| Site: | Haddam Neck File:Connecticut Yankee Atomic Power Co icon.png |
| Issue date: | 10/31/1981 |
| From: | Farmer F 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 EEG-EA-5634, EGG-EA-5634, NUDOCS 8112021014 | |
| Download: ML20033C298 (7) | |
Text
EGG-EA-5634 OCTOBER 1981 dr SYSTDtATIC EVALUATION PROGRAM TOPIC VI-7.C.1, 90sd hPc4 INDEPENDENCE OF REDUNDANT ONSITE POWER SYSTEMS, yygs HADDAM NECK A}SIO QR6. Researc r ad et ~fTNLducad,.
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- &4d f.' N.be This is an informal report intended for use as a preliminary or working document I
Prepared for the U.S. Nuclear Regulatory Commission Under DOE Contract No. DE-AC07-76ID01570 l
l FIN No. A6425-1 h EGrG,s.n.
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Idaho, Inc.
FORM EG4G496 (Rev 1179g INTERIM REPORT Accession No.
Report No.
EGG-EA-5634 Contract Program or Project
Title:
Electrical, Instrumentation, and Control Systems Support for the Systematic Evaluation Program (II)
Subject of this Document:
Systematic Evaluation Program Topic VI-7.C.1, Independence of Redundant Onsite Power Systems, Haddam Neck Type of Document:
Informal Report Author (s):
F. G. Farmer D:te of Document:
October 1981 R:sponsible 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 Washing'on, D.C.
Under DOE Contract No. DE AC07-76f D01570 NRC FIN No. A6425-1 INTERIM REPORT I
n Ol85J SYSTEMATIC EVALUATION PROGRAM TOPIC VI-7.C.1 INDEPENDENCE OF REDUNDANT ONSITE POWER SYSTEMS HADDAM NECK Docket No. 50-213 October 1981 F. G. Farmer 9
10-23-81
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l ABSTRACT-This SEP Technical Evaluation, for the Haddam Neck Plant, reviews the electrical independence between redundant. standby (onsite) power sources.
and their distribution -gystems.
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.
1 The U.S. Nuclear Regulatory Commission funded the work under the authorization B&R 20-10-02-05, FIN A6425-1.
l' i
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CONTENTS 1.0 I N TR O D UC T I O N....................................................
I 2.0 CRITERIA........................................................
1 2.1 AC Supplies...............................................
1 2.2 DC Supplies...............................................
1 3.0 DISCUSSION AND EVALUATION.......................................
1 3.1 AC Supplies...............................................
1 3.2 DC Supplies...............................................
2 4.0
SUMMARY
2
5.0 REFERENCES
2 iii
SEP TECHNICAL EVALUATION TOPIC VI-7.C.1
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INDEPENDENCE OF REDUNDANT 0NSITE POWER SYSTEMS HADDAM NECK l.0 INTRODUCTION The objective of this review is to determine if the onsite electrical.
power systems (AC and DC) are in compliance with current licensing criteria for electrical independence 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 sufficient inde-pendence to perform their safety function assuming a single failure. Regu-latory Guide 1.6, " Independence Between Redundant Standby (Onsite) Power Sources and Between Their Distribution System," and IEEE Standard 308-1974, "IEEE Standard Criteria for Nuclear Power Generating Stations" provide a basis acceptable to the NRC staff for meeting GDC 17 in regards to electri-cal independence of onsite power systems.
2.0 CRITERIA 2.1 AC Supplies. 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 1
another load group under accident conditions (2) No provisions should exist for automatically transfer-ring 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 be pro-vided to prevent an operator error that would parallel their standby power sources.
2.2 DC Supplies. Each DC load group should be energized by a battery and chargur. The battery-charger combination should have no automatic i
connection to any other redundant DC load group.
3.0 DISCUSSION AND EVALUATION 3.1 AC Supplies 2
3.1.1 Discussion. The Haddam Neck onsite standby AC power system consists of two redundant diesel emergency-generator (EG) supplied trains.
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During accident conditions, EG-2A supplies 4160 V bus 8 and, through trans-former 485,480Vbus1-5andMCC8-5;EG-2Bsuppligs4160Vbus9and, through transformer 496, 480 V bus 1-6 and MCC 8-6.
MCCs 5-5 and 5-6 may be supplied from either bus 1-5 or 1-6.
Breakers 2T8, 8T2, 3T9, and 9T3 open on loss of offsite power. Breakers 4T5 and 6T7 close on loss of offsite power. The Haddam Neck system includes three breakers (manual),
which are neither interlocked nor procedurally controlled, that permit paralleling divisions A and B; these are the tie breakers between MCCs 3-4 and 3-7, 4-4 and.4-7, ~ and 8-5 and 8-6.
Paralleling of buses 1-5 and 1-6 has been prevented by removal of tie breaker ST6 from its cubicle, key locks on the containment air recirculation fan circuits, and a.throwover scheme which prevents MCCs 5-5 and 5-6 from being supplied simultaneously by buses 1-5 and 1-6.
3.1.2 Evaluation. The Haddam Neck onsite standby AC power system does not meet current licensing criteria because MCCs 3-4 and 3-7, 4-4 and 4-7, and 8-5 and 8-6 can be tied together while each is being supplied from-different power divisions.
3.2 DC Supplies 3.2.1 Discussion. The Haddam Neck onsite standby DC power system consistso{twobatteries,twobatterychargers,twoDCbuses,andfour inverters.
A manual bus tie breaker exists between the two buses; no interlocks or procedures prevent paralleling the two batteries via this breaker.4 Interlocks prevent the connection of any inverter input to both buses simultaneously, but each inverter can be supplied from either DC bus, i.e., all four inverters (and their loads) may be supplied from only one battery.
3.2.2 Evaluation. While there are not automatic transfers of any redundant DC load groups, the batteries may be paralleled by the manual bus tie breaker; also, all four inverters may be supplied by a single bat-tery. Neither of these arrangements complies with the intent of RG l.6.
4.0
SUMMARY
The Haddam Neck onsite standby AC and DC power systems do not comply with current. licensing criteria.
In each case, at least one manual breaker exists which allows paralleling of the two power divisions; no interlocks or procedures prevent this. Additionally, the DC power system design per-mits all four inverters to be supplied from a single battery.
5.0 REFERENCES
1.
General Design Criterions 17, " Electrical Power System," of Appen-dix A, " General Design Criteria of Nuclear Power Plants," to 10 CFR Part 50, " Domestic Licensing of Production and Utilization Facilities."
2.
" Independence Between Redundant Standby (0nsite) Power Sources and Between Their Distribution Systems," Regulatory Guide 1.6.
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3.
"IEEE Standard Criteria for Nuclear Power Generating Stations," IEEE Standard 308-1974, The Institute of Electrical and Electronic Engineers, Inc.
4 Letter, CYAPCo (Counsil) to NRC (Ziemann), dated March 6,1980.
5.
Northeast Utilities Service Co. drawing for CYAPCo, Drawing 161003-30055, Revision 2, dated 8-14-79.
6.
Letter, CYAPCo (Counsil) to NRR (Crutchfield), dated September 4, 1980.
6 3