ML19350B156
| ML19350B156 | |
| Person / Time | |
|---|---|
| Site: | Oconee, Mcguire, Catawba, McGuire  |
| Issue date: | 03/13/1981 |
| From: | James O'Reilly NRC OFFICE OF INSPECTION & ENFORCEMENT (IE REGION II) |
| To: | Parker W DUKE POWER CO. |
| References | |
| NUDOCS 8103200013 | |
| Download: ML19350B156 (1) | |
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'o UNITED STATES l"
,( j7,g NUCLEAR REGULATORY COMMISSION
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e REGION II
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oi" 101 MARIETTA ST., N.W SUITE 3100 I
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ATLANTA, GEORGIA 30303 f.1AR 11 1981 In Reply Refer To:
RII:JP0 50-369, 50-370 fokV($LLLO 50-269, 50-270 50-287, M y 4
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A, h3 Duke Power Company M.
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ATTN:
W. O. Parker, Jr.
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. Vice President, Steam Production.
"P'.'O. Box'2178'
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\\,('rg Charlotte, NC 28242
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Gentlemen:
The enclosed IE Information Notice No. 81-05 contains information that may be applicable to your facility regarding the consequences of a degraded dc system.
No specific actions or responses are requested at this time; however, pending the results of an ongoing NRC staff evaluation of this matter,.further licensee actions may be requested.
Should you have any questions regarding this information notice, please contact
. this office.
- ~1cerely, n
qy%.M James P. O' Reil y Director.
Enclosures:
1.
IE Information Notice No. 81-05 2.
List 'of Recently Issued
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.IE Information Notices t
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cc w/ encl:
-M. D. McIntosh. Plant Manager J. C.? Rogers, Project Manager-J.-E. Smith, Station Manager D. G.. Beam, Project Manager J. W. Hampton, Station Manager 810 82 0 0 'Ol}
SSINS No..
6835 Accession No.:
8011040271 IN 81-05 UNITED STATES
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} q r-f NUCLEAR REGULATORY COMMISSION jI OFFICE OF INSPECTION AND ENFORCEMENT 2
WASHINGTON, D.C.
20555 March 13, 1981 IE INFORMATION NOTICE No. 81-05:
DEGRADED DC SYSTEM AT PALISADES
Purpose:
. The in_ tent gf this notice.is to enhance nuclear power plant safety by
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-f = proving' ths r'eliability of 'the-direct curr'ent (de) distribution system in -
nuclear power plants.
Toward this end, this information notice alerts holders of operating licenses and construction permits of an event that degraded the dc system at the Palisades facility and jeopardized plant safety.
Description of Circumstances:
On January 6, 1981, while performing monthly surveillance tests on both station batteries, maintenance personnel inadvertently opened the breakers from both station batteries to their 125 volt dc buses and left them open for approxi-mately one hour. We view this personnel error as a common-mode failure that, if left uncorrected, would lead to a complete station blackout [i.e., total loss of both alternating current (ac) and de power].
Since the plant was in a normal mode of operation, de power was being supplied by the ac system via the battery chargers; therefore, de power was never interrupted during this period. Nevertheless, as described later, the safety of the plant was jeopardized.
A' loss of offsite power during this period would,
-in-the absence of manual action,r result in the loss of all control power, blocking the automatic transfer of power to the onsite diesel generators.
In many. designs, such loss.es.would-also block the starting of the diesels.
In contrast, the' Palisades -design would ~n'ot block the ~ starting of' the ' diesels; however, the loss of control power would block the connecting of the generators to their emergency buses so that a complete station blackout would still result.
In either case, _ the blackout would persist until the battery breakers were 3~
manually reciosed or manual actions taken (e.g., manually closing the breakers from the diesel generators to their emergency buses and the required down stream y-
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load breakers.) During this time the ability of the plant to remove decay heat would be severely restricted. Since the tripping of the battery breakers is not' annunciated in the Palisades control room, a subsequent loss of offsite power.would lead to an undetected common-mode failure. - Such a failure would be difficult to diagnose, thereby limiting the operator's ability 'to take timely corrective action.
Consequently, an inordinate amount of time could be required to bring the_ plant'to a normal mode of decay heat removal.
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IN 81-05 Marcn 13, 1981 Page 2 ef 2 Plants cesigned to conform with Regulatory Guide 1.47, "Bycassed and Incperacle Status Indication for Nuclear Power Plant Safety," will automatically alert the coerator whenever a battery is cisconnected from its bus, thereby creclucing a Palisades type of event.
As a corrective measure, Palisades is planning to install annunciators in the control room that will alert the c;eratcr wnenever a station battery has been disconnected from its bus.
The information herein is being provided as an early notification of a possibly significant matter that is still uncer review by the NRC staff Recipients should review the information for cossiole acclicability to their facilities.
If NRC evaluations so incicate, further licensee actions may be requested.
No written response to this Information Notice is re;uirec.
If you desire additional information regarding this matter, contact the Director of tne appropriate NRC Regional Office.
Attachment:
Recently issued IE Information Notices e
Attachment IN 81-05 March 13, 1981 i
RECENTLY ISSUED IE INFORMATION NOTICES Information Date of Notice No.
Subject Issue Issued to 81-06 Failure of ITE Mocel 3/11/81 All power reactor K-600 Circuit Breaker facilities with an OL or CP 81-04 Cracking in Main Steam 2/27/81 All power reactor Lines facilities with an OL 81-03 Checklist for Licensees 2/12/81 All power reactor Making Notifications of facilities with an Significant Events in OL Accordance with 10 CFR 50.72 81-02 Transportation of 1/23/81 All Radiography Radiography Devices licensees 81-01 Possible Failures of 1/16/81 All power reactor General Electric Type facilities with an 4
80-45 Potential Failure of 12/17/80 All PWR facilities BWR Backup Manual Scram with an OL or CP Capability 80-44 Actuat.fon of_ECCS in-the, 12/16/80-AllsPWR facilities-Recirculation' Mode While with an OL or CP in Hot, Shutdown 80-43 Failures of the Continuous 12/5/80 All power reactor Water Level Monitor for facilities with an the Scram Discharge Volume OL or CP at Dresden Unit No. 2
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80-42 Effect of Radiation on 11/24/80 All power reactor Hydraulic Snubber Fluid facilities with an OL or CP OL_= Operating Licenses LCP = Construction Permits r