ML19350B172
| ML19350B172 | |
| Person / Time | |
|---|---|
| Site: | Hatch, Vogtle  |
| Issue date: | 03/13/1981 |
| From: | James O'Reilly NRC OFFICE OF INSPECTION & ENFORCEMENT (IE REGION II) |
| To: | John Miller GEORGIA POWER CO. |
| References | |
| NUDOCS 8103200036 | |
| Download: ML19350B172 (1) | |
Text
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,, f jo, UNITED STATES
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j NUCLEAR REGULATORY COMMISSION e
REGION 11 o,
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101 MARIETTA ST.. N.W.. SUITE 3100 ATLANTA, G EoRGIA 30303
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MAR la 1931 In Reply Refer To:
RII:JP0 diDT21, 50-36_D 50-424, 50-425 Georgia Power Company ATTN:
J. H. Miller, Jr.
Executive Vice President 270 Peachtrae Street Atlanta, GA 30303 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 regr.rding this information notice, please contact this office.
Sincerely, L
M e-c James P. O'Reilly Director D.Qg 'D
Enclosures:
s 1.
IE Information Notice No. 81-05 2.
List of Recently Issued
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f'J %p IE Information Notices 0%
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M. Mar, y, Plant Manager f
C. E. Be " lower, Site QA Supervisor g
q W. A. Widner, Vice President and M
General Manager-Nuclear Generation Qg e
K.' M. Gillespie, Construction Pro.'ect Manager E. D. Groover, QA Site Supervisor D. E. Dutton, Project General Manager i
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8108200036 Q
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A SSINS No.:
6835 Accession No.:
8011040271 IN 81-05
[3M UNITED STATES hh NUCLEAR REGULATORY CCMMISSION 0FFICE OF INSPECTION AND ENFORCEMENT WASHINGTON, D.C.
20555 March 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 (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 de 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 de buses and left them open for approxi-mately one hour. We view this personnel error as a common-mode failure that, if lef t uncorrected, would. lead to a complete station blackout [i.e., total loss of both alternating current (ac) and dc 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 jeoparoized. A loss of offsite power during this period would, in the, absence of, manual action, resultzin the loss of all control power, blocking the a'utiomatic transfer of ' power to the onsite diesel generat' ors.
In many designs, such losses would also block the starting of the diesels.
In
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contrast, the Palisades design w'ould not 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 manually reclosed or manual actions taken (e.g., manually closing the breakers
- from the diesel generators to their emergency buses and the required down stream y
load breakers.) During this time the ability of the plant to remove decay heat would be severely restricted.
Since the tripping of the battery breakars 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 March 13, 1981 Page 2 of 2 Plants designed to conform with Regulatory Guide 1.47, "Bycassed and Inoperable Status Indication for Nuclear Power Plant Safety," will automatically alert the operator whenever a cattery is disconnected from its bus, thereby precluding a Palisades type of event. As a corrective measure, Palisades is planning to install annunciators in the control room tnat will alert tne operator whenever 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 under review by the NRC staff.
Recipients 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 Informaticn Notice is required.
If you desire i
additional informatien regarding this matter, contact the Director of the appropriate NRC Regional Office.
Attachment:
Recently issued IE Information Notices g
S
e Attachment IN 31-05 March 13, 1981 s
RECENTLY ISSUED IE INFORM.ATION NOTICES Information Date of Notice No.
Subject Issue Issued to 81-06 Failure of ITE Model 3/11/31 All power reactor K-600 Circuit Breaker facilities with an OL or CP 81-04 Cracking in Main Steam 2/27/81 All pcwer reactor Lines facilities with an CL 81-03 Checklist for Licensees 2/12/51 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 pcwer reactor General Electric Type facilities with an HFA Relays OL or CP.
80-45 Potential Failure of 12/17/80 All PWR facilities BWR Backup Manual Scram with an OL or CP Capability 80-44
. Actuation.of ECCS in the 12/16/80 All PWR facilities Recirculation Mode While wit' an OL or CP in Hot Shutdown
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80-43 Failures of the Continuous 12/5/80 All power reactor Water Level Monitor for facilities with an the Scrum Discharge Volume OL or CP at Dresden Unit No. 2 80-42 Effect of Radiation on 11/24/80 All power reactor Hydraulic Snutber Fluid facilities with an OL or CP OL = Cperating Licenses CP = Construction Permits s