ML20010G668
| ML20010G668 | |
| Person / Time | |
|---|---|
| Site: | Millstone  |
| Issue date: | 09/11/1981 |
| From: | Crutchfield D Office of Nuclear Reactor Regulation |
| To: | Counsil W NORTHEAST NUCLEAR ENERGY CO. |
| References | |
| TASK-06-07.C1, TASK-6-7.C1, TASK-RR LSO5-81-09-032, LSO5-81-9-32, NUDOCS 8109220382 | |
| Download: ML20010G668 (11) | |
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1 S6ptember 11, 1981 Docket No. 50-245
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LS05 09-032
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?A ' /"o,/g [s Mr. W. C. Counsil. Vice President
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Nuclear Engineering and Operations 0
Norhteast Nuclear Energy Company 1
Post Office Box 270 k.
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Hartford, Connecticut 06101
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Dear Mr. Counsil;
SUBJECT:
SEP TOPIC VI-7.C.l. APPENDIX X - ELECTRICAL INSTRUMENTATION AND CONTROL (EI&C) RE-REVIEWS, SAFETY EVALUATION FOR MILLSTONE UNIT 1 Erclosure 1 is our contractor's final evaluation of this topic. The evalua-tion has been revised to reflect the comments made during our August 12, 1981 phone conference with your staff. is the staff Safety evaluation that is based upon Enclosure 1 and supplements our contractor's evaluation. This evaluation supports the findings of the enclosed staff safety evaluation on Topic VI-7.C.1 that proposes modifications to Class 1E tie breater controls.
The need to actually implement these changes will be detemined dun ing the integrated plant safety assessment. This topic assessment may be revised in the future if your facility design is changed or if NRC criteria relating to this topic are modified before the integrated assessment is completed.
Sincarely, Dennis H. Crutchfield, Chief Operating Reactors Branch No. r5 Division of Licensing 56o1
Enclosures:
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As stated
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September 11, 1981 Docket No. 50-245 LS05-81-09-032 Mr. W. G. Counsil, Vice President Nuclear Engineering and Operations Norhteast Nuclear Energy Company Post Office Box 270 Hartford, Connecticut 06101
Dear Mr. Counsil:
SUBJECT:
SEP TOPIC VI-7.C.1, APPENDIX K - ELECTRICAL INSTRUMENTATION AND CONTROL (EI&C) RE-REVIEWS, SAFETY EVALUATION FOR MILLSTONE UNIT 1 is our contractor's final evaluation of this topic. The evalua-tion has been revised to reflect the comments made'during our August 12, 1981 phone conference with your staff. is the staff safety evaluation that is based upon Enclosure 1, and supplement; our contractor's evaluation. This evaluation supports the findings of the enclosed staff safety evaluation on icpic VI-7.C.1 that proposes modifications to Class 1E tie breaker controls.
The need to actually implement these changes will be determined during the integrated plant safety assessment. This topic assessment may be revised in the future if your facility design is changed or if NRC criteria relating to this topic are modified before the integrated assessment is completed.
Sincerely, x Q ief;d Denn s M. Crutch ield, Operating Reactors Branch No. 6 Division of Licensing
Enclosures:
l As stated 1
l cc w/ enclosures:
See next page l
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F11LLSTONE 1 Docket No. 50-245 Mr. W. G. Counsil 1
cc Wilham H. Cuddy, Esquire Connecticut Energy Agency Day, Berry & Howard ATTN: Assistant Director Counselors at Law Research and Policy One Constitution Plaza Development Hartford, Connecticut 06103 Department of Planning and Energy Policy Natural Resources Defense Council 20 Grand Street 91715th Street, N. W.
Hartford, Connecticut 06106 Washington, D. C.
20005 Northeast Nuclear Energy Conpany ATTN: Superintendent Millstone Plant P. O. Box 128 Waterford, Connecticut 06385 Mr. Richard T. Laudenat Manager, Generation Facilities Licensing Northeast Utilities Service Company P. O. Box 270 Hartford, Connecticut 06101 Resident Inspector c/o U. S. NRC P. O. Box Drawer KK Niantic, ';ciciecticut 06357 Waterford Public Library Rope Ferry Road, Route 156 Waterford, Connecticut 06385 First Selectman of the Town of Waterford Hall of Records 200 Boston Post Road l
Waterford, Connecticut 06385 John F. Opeka Systems Superintendent l
Northeast Utilities Service Company i
P. O. Box 270 Hartford, Connecticut 06101 U. S. Environmental Protection Agency Region 1 Office
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ATTN: EIS C0ORDINATOR JFK Federal Building Boston, Massachusetts 02203 l
TOPIC: VI-7.C.1 APPENDIX K - ELECTRICAL INSTRUMENTATION AND CONTROL
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I.
INTRODUCTION During the Appendix K reviews of some facilities initially considered, a detailed EI&C review was not performed. Accordingly we intended to re-review the rodified ECCS of these facilities to confirm that it is designed to meet the most limiting single failure. Several types of failure were considered a> candidates for designation as the most limiting. Because of the scope of the other SEP Topics, it was decided that, for the purpose of this study (and to reduce replication of effort on other SEP Topics),
the loss of a single ac or de onsite power system was the most limiting failure. Accordingly, this topic was limited to an evaluation of the independence between the onsite power syst?ms.
II.
REVIEW CRITERIA The review criteria are presented in Section 2 of EG8G Report 0124J.
" Independence of Redundant Onsite Power Systems."
III.
RELATED SAFETY TOPICS AND INTERFACES The scope of review for this topic was limited to avoid duplication of effort since some aspects of the review were performed under related topics. The related topics and the subject matter are identified below.
Each of the b.
related topic reports contain the acceptance criteria and review guidance for its subject matter.
VI-4 Bypass and Reset of Enginecred Safpty Features (B-24)'
VI-7,A.3 ECCS Actuation System VI-7.B ESF Switchover from Injection to Recirculation VI-7.C.2 Failure Mode Analysis-ECCS VI-7 D Long Term Cooling Passive Failures (e.g., flooding)
VI-10. A Testing of Reactor Protection Systems VII-1.A Reactor Trip System Isolation VII-3 Systems Required for Safe Shutdown VIII-2 Onsite Emergency Power Systems VIII-3 Emergene" de Power Systems VIII-4 Electrical Penetrations i
IX-6 Fire Protection The conclusion that suitable isolation devices are provided is a basic l
assumption for Topics VI-7.C.2 snd VII-3.
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' t IV. REVIEW GUIDELINES The review auidelines are presented in Section 3 of Report 0124J,
" Independence of Redundant Onsite Power Systems".
V.
EVALUATION As noted in Report 0124J, " Independence of Redundant Onsite Power Systems',', the separation between redundant systems is compromised by
' the onsite, power system.
At Millstone 1, buses 2-3NE, 22A-1 and the 120V ac instrument bus are supplied from automatic transfer switches which can transfer loads between redundant sources and are therefore not in compliance with
' current licensing criteria The de system has three load centers s
which are manually transferred between redundant sources under admin-istrative control. Tnere are no interlocks to prevent an operat6r error that would parallel the de buses with their emergency source and they are therefore not in compliance with current licensing cri-ter.ia.
VI. CONCLUSION Ac a result of our review of our contractor's work the staff concludes that the subject ac and de onsite systems do not satisfy all of the review criteria, We propose that the ac automatic transfers be deleted or justified upon sane technical basis that demonstrates compliance with the single failure criterion. We also propose that suitable interlocks be pro-vided.for the de transfers.
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l SEP TECHNICAL EVALUATION TOPIC VI-7.C.1 INDEPENDENCE OF REDUNDANT ONSITE POWER siSTEMS DRAFT MILLSTONE NUCLEAK STATION, UNIT 1 l
Docket No. 50-245 August 1981 EG&G, IDAHO FALLS
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CONTENTS i
1.0 INTRODUCTION
I 2.0 CRITERIA........................................................
1 2.1 AC Supplies...............................................
I 2.2 DC Supplies...............................................
2 3.0 DISCUSSION AND EVALUATION.......................................
2 3.1 AC System...................,.............................
2 3.2 DC System.................................................
3 4.0
SUMMARY
3 S.0 REFERENCES....................................................
4 i
E.
's TECHNICAL EVALUATION INCEPENDENCE OF REDUNDANT ONSITE POWER SYSTEMS MILLSTONE NUCLEAR STATION, UNIT 1
1.0 INTRODUCTION
The objective of this review is to determine if the onsite electrical power systems (AC and DC) are in compliance witn current licensing criteria for electrical independence between redundant standby (onsite) power sources and their distribution systems.
General Design Criterion 17 requires that tne onsite electrical power sunplies and their onsite distribution systems shall have sufficient ince-pendence to perform their safety function assuming a single failure. Regu-latory Guice 1.6, " Independence Between Redundant Standby (Onsite) Power Scurces and Between Their Distribution System," ana IEEE Standard 308-1974, "IEEE Standard Criteria for Nuclear Power Generating Stations" provide a basis acceptaole to tne NRC staff for meeting GDC 17 in regards to electri-cal independence of onsite power systems.
2.0 CRITERIA 2.1 AC Supolies. When operating from standby sources, redundant load l
groups ar.1 redundant standby sources should be independent of each other at least to the following extent.
(1) The standby sourca of one load group should not be l
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 1
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be provided to preventi an operator error that would parallel their standby power sources.
2.2 DC Supolies. Each DC lead group sh.ould be energized by a battery l
anc cattery cnarger. Tne battery-charger. combination should have no auto-matic connection to any other reaundant DC load group.
3.0 DISCUSSION AND EVALUATION 3.1 AC System. Millstone 1 emergency AC oower is orovided by a gas j
turbine generator (GTG) and a diesel generator.(CG). The GTG normally supplies buses 7, 1, 3, and 5 upon loss of auxiliary power. The DG nor-mally supplies bus 6.
There are no provisions for connecting 4160 V buses 1
supplied by recuncant sources.
l Millstone I has four main 480 V AC buses,1, lA, 2, and 2A, wnich are j
_ supplied by 4160 buses 3, 4, 5,~and 6, respectively. Buses 1 and'lA and 2 and 2A have tie breakers. There are electrical interlocks that prevent closing the tie creaker unless one of the main feeders for the two buses is In orocr to close the main feeder for eitner cus, tne tie must be open.
j trippec. MCCs 2-3NE, 2A-3NE and 22A-1 can be supplied from 480V buses 2 or 2A througn auto-transfer switenes which is not in compliance with the requirement for no automatic transfer of loads between redundant sources.
The 120 V AC vital cus is supplied by an autcmatic transfer device i
receiving power from either bus 2A-5 or the vital moter generator set (vital MG). The MG is powered either from bus DC-IIA-3 or cu: 2-5.
Therefore, the automatic transfer does not occur between redundant sources of power.
The 120 V AC instrument bus is supplied by an automatic transfer device receiving power from buses 2-4 or 2A-5 which are supplied from redundant sources and is, therefore, not in compliance with the requirements for no automatic transfer of loads between redundant sources.
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The reactor protection system buses 1 and 1A are supplied from MCC 2-5 (GTG) and 2A-5 (6G) respectively. A manual tie breaker at each bus is pro-vided with a mechanical interlock, wnicn will prevent paralleling the two sources.
3.2 OC Systems. The Millstone 1 OC system consists of two 125 V batteries and their respective chargers, a stanaby charger capable of sup-plying either battery, and the DC distribution system. The cuput breakers of the stanoby charger are mechanically interlockeo to prevent paralleling 1
of the two DC batteries and their buses.
The main DC buses, DC-1 and DC-1A, are powered from batteries 1 and 1A, respectively. The three load centers, OC-llA-1, DC-ilA-2, and DC-IIA-3, are powered from either bus DC-1 or DC-1A via manual transfer switches wnich are administratively controlled.
The circuit breakers which supply the emergency power from DC-1 or DC-1A to DC-llA-1,
-2, or -3, are open. How-ever there are no interlocks to prevent paralleling the normal and emergency sources.
4.0
SUMMARY
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The onsite amergency AC system at Millstone 1 is in compliance with j
current licensing criteria for independence of redundant onsite power sys-tems with the exception of MCCs buses 2-3NE, 2A-3NE, 22A-1 and the 120V AC instrument bus. These buses are supplied from automatic transfer switches l
wnich can transfer loacs cetween redundant sources and are therefore not in I
j compliance with current licensing criteria. The DC system has three load i
centers which are manually transferred between redundant sources and are, under aaministrative control. There are no interlocks to prevent an oper-
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ator error that would parallel the DC buses with their emergency source and are therefore not in compliance with current licensing criteria.
5.0 REFERENCES
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1.
General Design Criterion 17, " Electrical Power System," of Appendix A,
" General Design Criteria of Nuclear Power Plants," to 10 CFR Part 50,
" Domestic Licensing of Production and tJtilization Facilities."
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,s 2.
"Independance Between Redundant Standby (Onsite) Power Sources ana Between Their Distribution Systems," Regulatcry Guide 1.6.
3.
Millstone 1 Orawings 25202-31001, Sheets 110, lil, 112, 130, 131, 271, 276, 291, 292, 300, 301, 311, 321, 322, 323, 324, ana 605.
4 Final Safety Analysis Report, Millstone Nuclear Power Station, Unit 1.
5.
Telcon, R. Scholl, NRC, D. Weber, EG&G Idaho, Inc., W. Mission and P. Blasiali, Northeast Utilities, August 12, 1981.
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