ML19350B142
| ML19350B142 | |
| Person / Time | |
|---|---|
| Site: | Farley  |
| Issue date: | 03/13/1981 |
| From: | James O'Reilly NRC OFFICE OF INSPECTION & ENFORCEMENT (IE REGION II) |
| To: | Mcdonald R ALABAMA POWER CO. |
| References | |
| NUDOCS 8103190864 | |
| Download: ML19350B142 (1) | |
Text
P
/yt>2"ECyc UNITED STATES
'k NUCLEAR REGULATORY COMMISSION
$.g "7 r g [i REGION ll o,
101 MARIETTA ST., N.W., SulTE 3100 j'
ATLANTA, G EoRGIA 30MJ
'!AR 1 i G31 In Reply Refer To:
RILJPO-co N h
Alabama Power Company i
W ATTN:
R. P. Mcdonald
$9 "g'E.l 6 Vice President-Nuclear Generation C # %
081 6
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P. O. Box 2641
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Birmingham, AL 35291
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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 de 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.
Sincerely, Lh C t % N 1 f.y James P. O'Reii Director
Enclosures:
1.
IE Information Notice No. 81-05 2.
List of Recently> Issued' IE Information Notices cc w/ encl:
W. O. Whitt, Executive Vice President F. L. Clayton, Jr., Senior Vice President
~
H. O. Thrash, Manager-Nuclear Generation
- 0. D. Kingsley, Jr., Manager, Nuclear Engineering and Technical Services J. W. McGowan, Manager-Operaticas Quality Assurance W. G. Hairston, III, Plant Manager W. C. Petty, Manager-Quality Assurance (Design and Construction)
R. E. Hollands, Jr., QA Supervisor 8103190 $ f
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SSTNS No.:
6835 Accession No.:
8011040271 IN 81-05 UNITED STATES NUCLEAR REGULATORY CCMMISSION
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OFFICE OF INSPECTICM AND ENFORCEMENT 3 J mg
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WASHINGTON, G.C.
20555 Maren 13, 1981 IE INFORMATION NOTICE No. 81-05:
DEGRADED DC SYSTEM AT PALISADES
Purpose:
The intent of this notice is to enhance nuclear power plant safety by improving the reliability of the direct current (dC) distribution system in nuclear power plants.
Toward this end, this information notice alerts holders of operating licecses and construction permits of an event that degraded the de system at th? 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 de 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 dc powar].
Since the plant was in a normal mode of operation, dc power was being supplied by the ac system via the battery chargers; tnerefore, de power was nevar 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,' result-in. the loss. of. all control power, blocking the automatic transfer of power to the onsite diesel generators.
In many designs, such losses would.also block the starting of the diesels.
In contrast','the Palis~ades' design would not block # the starting of the die ~sels; however, the loss of control power would block the connecting of the generators to their emergency buses 5a that a complete station blackout would still result.
In either case, the blackoet would persist until the battery breakers were manually reclosed or manual actions taken (e.g., manually closing the breakers from the diese? generators to their emergency buses and the required down stream 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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r Jk Attachment IN 81-05 March 13, 1981 RECENTLY ISSUED IE INFORMATION NOTICES Information Date of Notice No.
Subject Issue Issued to 81-06 Failure of ITE Model 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 2/12/31 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 HFA Relays OL or CP. 45
- Potential. Failure of-12/17/80 All PWR facilities EdR Backup Manuil Scram
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Capability
. 80-44.,
Actuation of ECCS in the 12/16/80 All.PWR facilities
.Recirculatior. Mode While with an OL or CP
-'in Hot Shutdown z
80-43 Failures ofothe Continuous 12/5/80
- All power resctor Water Level Monitar for facilities with an the Scram Discharge Volume OL or CP at Dresden Unit No. 2 80-42 Effect of-Radiation en 11/24/80 All power reactor Hydr aulic Snubber Fluid facilities with an OL or CP OL = Operating Licenses
- CP = Construction Permits e
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