ML19321A793
| ML19321A793 | |
| Person / Time | |
|---|---|
| Site: | Crystal River  |
| Issue date: | 05/08/1980 |
| From: | James O'Reilly NRC OFFICE OF INSPECTION & ENFORCEMENT (IE REGION II) |
| To: | Hancock J FLORIDA POWER CORP. |
| References | |
| NUDOCS 8007240202 | |
| Download: ML19321A793 (1) | |
Text
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'o, UNITED STATES
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NUCLEAR REGULATORY COMMISSION g
9 a REGION 11 o
101 MARIETTA ST., N.W., SUITE 3100 o
ATLANTA, GEORGIA 30303 MAY 8 1980 In Reply Refer To:
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s Florida Power Corporation Attn:
J. A. Hancock, Director Nuclear Operations P. O. Box 14042, Mail Stop C-4 St. Petersburg, Florida 33733 Gentlemen:
The enclosed Information Notice provides early notification of an event j
that may have safety significance. Accordingly, you should review the Information Notice for possible applicability to your facility.
No specific action or response is requested at this time; however, con-tingent upon the results of further staff evaluation, a Bulletin or Circular recommending or requesting specific licensee actions may be issued.
If you have questions regarding this matter, please contact me.
Sincerely, w~~t James P. O'Reilly Director
Enclosures:
1.
IE Information Notice No. 8 0.-20 2.
List of Recently Issued 1
IE Information Notices
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8007240202_
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MY 8 1980 Florida Power Corporation,
cc w/ encl:
D. C. Poole Nuclear Plant Manager Post Office Box 1240 Crystal River, Florida 32629
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0 SSINS No.:
6870 UNITED STATES Accession No.:
NUCLEAR REGULATORY COMMISSION 8002280671 0FFICE OF INSPECTION AND ENFORCEMENT WASHINGTON, D. C. 20555 May 8, 1980 IE Information Notice 80-20 LOSS OF DECAY HEAT REMOVAL CAPABILITY AT DAVIS;BESSE TNIT ~1 WHILE IN A REFUELING MODE Description of Circumstances:
On April 19, 1980, decay heat removal capability was lost at Davis-Besse Unit 1 for approximately two and one-half hours. At the time of the event, the unit was in a refueling mode (e.g., RCS temperature was 90F; decay heat was being removed by Decay Heat Loop No. 2; the vessel head was detensioned with bolts in place; the reactor coolant level was slightly below the vessel head flanges; and the mar.way covers on top of the once through steam generators were removed).
(See Enclosure A, Status of Davis-Besse 1 Prior to Loss of Power to Busses E-2 and F-2 for additional details regarding this event.)
Since the plant was in a refueling mode, many systems or components were out of service for maintenance or testing purposes.
In addition, other systems and components were deactivated to preclude their inadvertent actuation while in a refueling mode. Systems and components that were not in service or deactivated included:
Containment Spray System; High Pressure Injection System; j
Source Range Channel 2; Decay Heat Loop No. 1; Station Battery IP and IN; Emergency Diesel-Generator No. 1; 4.16 KV Essential Switchgear Bus C1; and 13.8 KV Swit-hgear Bus A (this bus was energized but not aligned).
In brief, the event was Jue to the tripping of a non-safeguards feeder breaker 1
4 in 13.8 KV Switchgear Bus 3. Because of the extensive maintenance and testing activities being conducted at. the time, Channels 1 and 3 of the Reactor Protec-tion System (RPS) and Safety Features Actuation System (SFAS) were being ener-gized from only one source, the source emanating from the tripped breaker.
Since the SFAS logic used at Davis-Besse is a two-out-of-four input scheme in which the loss (or actuation) of any two input signals results in the actuation of all four output channels (i.e., Channels I and 3, and Channels 2 and 4), the loss of power to Channels 1 and 3 bistables also resulted in actuation of RFAR Channels 2 and 4.
The actuation of.x Decay Heat Loop No. 2, the operating 1
.f 4
Since the initiating event was a loss i
DUPLICATE DOCUMENT were actuated (i.e., level 1 - High Ra 1
tion; Level 3 - Low Pressure Injection
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