ML19350B192
| ML19350B192 | |
| Person / Time | |
|---|---|
| Site: | Satsop |
| Issue date: | 03/13/1981 |
| From: | Engelken R NRC OFFICE OF INSPECTION & ENFORCEMENT (IE REGION V) |
| To: | Dobson D WASHINGTON PUBLIC POWER SUPPLY SYSTEM |
| References | |
| NUDOCS 8103200066 | |
| Download: ML19350B192 (1) | |
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UNITED STATES 8
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' Attn: Mr. Dale Dobson, Acting Program Director Gentlemen:
The enclosed IE Information Notice No. 81-05 contains information that may be applicable to your facility regarding *.he 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 infomation notice, please contact this office.
Sincerely, e..
R. H. Engelken Director
Enclosures:
1.
IE Infomation Notice No. 81-05 2.
List of Recently Issued ~
IE Information Notices ccw/ enclosures:
M. E. Witherspoon, Quality Assurance Director
- 0. C. Sorensen, WPPSS 8103 2 00 DN Q
r SSINS No.: 6835 Accession No.:
8011040271 IN 81-05 9' lDf @
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UNITED STATES NUCLEAR REGULATOPY COMMISSION OFFICE OF INSPECTION AND ENFORCEMENT WASHINGTON, D.C.
20555 March 13, 1981 IE INFORMATION NOTICE N0. 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 licenses and construction pemits of an event that degraded the de system at the Palisades facility and jeopardized plant safety.
Description of Circumstances:
On ~ January 6,1981, while performing monthly surveillance tests on ath station batteries, maintenance personnel inadvertently opened the breakars from both mtion 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 Oi.e.., total loss of.both alternating current (ac) and de pwero.
Since the plant was in a normal mode of operation, dc power was being supplied by the ac system via the battery chargers; therefore, de power was never ir.errupted during this period. Nevertheless, as described later, the safety or 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 trar.sfer of power to the onsite diesel generators.
In many designr, such losses would also block the starting of the diesels.
In.
-contrast, the Palist. des design would nct-block the. starting of the diesels; however, the loss cf control pcwer would block the connecting of the generators to their emergency beses so that a complete station blackout would still result.
In either case, the ble.kout would persist until~ the battery breakers were manually reclosed or manual actions taken (e.g., manually closing the breakers from the-diesel-genarators to their emergency buses and the required down stream load breakers.). During this time the ability of the plant to remove decay heat *~uld 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.
Su:h a failure would be difficult to ' diagnose, thereby limiting the operator's ability to take timely corrective actian. Consequently, an inordinate amount of time could be required to bring the plant to a normal mode of decay heot removal.
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IN 81-05 March 13, 1981 Page 2 of 2 Plants designed to-conform with Regulatory Guide 1.47, " Bypassed and Inoperable Status Indication for Nuclear Power Plant Safety," will automatically alert the operator whenever a battery is disconr. acted from its bus, thereby precluding a Palisades type of event. As a corrective measure, Palisades is planning to install annunciators in the control room that will alert the operator whenever
'a station battery has been disconnected from its bus.
The informatien herein-is being provided as an early notification of a possibly significant matte.- that is still under revieu by the NRC staff. Reci ients should review the information for possible applicability to their facilities.
If NRC evaluations so indicate, further licensee actions may be requested.
No written response to this Information Notice is required.
If you desire additional information regarding this matter, contact the Director of the appropriate NRC. Regional Office.
Attachment:
Recently issued LIE'Infonmation Notices L -
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J Attachment IN 81-05 March 13, 1981 RECENTLY ISSUED IE INFORMATION NOTICES Information.
Date of Notice No.
Subject Issue Issued to 2
81-06 Failure of ITE Model 3/13/81 All power reactor K-600 Circuit Breaker facilities with an OL or CP 181-04 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 HFA Relays
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OL or CP. 45 Potential Failure of-12/17/80 All PWR' facilities
.BWR' Backup Manual Scram with an.0L or CP Capabili ty '
80-44
- Actuation of ECCS'in the.
12/16/80.
All -PWR 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 -
180-42 Effect' of Radiation on 11/24/80.
All power. reactor
- Hydraulic Snubber Fluid -
facilities with an' i
' OL = 0perating ' Licenses CP = Construction Permits ~
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