ML19309H748
| ML19309H748 | |
| Person / Time | |
|---|---|
| Site: | South Texas  |
| Issue date: | 05/08/1980 |
| From: | Seyfrit K NRC OFFICE OF INSPECTION & ENFORCEMENT (IE REGION IV) |
| To: | Eric Turner HOUSTON LIGHTING & POWER CO. |
| References | |
| NUDOCS 8005190671 | |
| Download: ML19309H748 (1) | |
Text
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UNITED STATES NSIC NUCLEAR REGULATORY COMMISSION CENTRAL FILES
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R EcloN IV 5
i) o 611 RY AN PLAZA DRIVE, SUITE 1000
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ARLINGTON, TEXAS 76012
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May 8, 1980 In Reply Refer To:
RIV Docket Nos. 50-498/IE Infor:aation Notice No. 80-20 50-499/IE Information Notice No. 80-20 Houston Lighting & Power Company ATTN:
Mr. E. A. Turner, Vice President Power Plant Construction and Technical Serrices Post Office Box 1700 Houston, Texas 77001 Gentlemen:
The enclosed IE Information Notice provides early notification of an event 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, contingent upon the results of further staff evaluation, a Bulletin or Circular recom-mending or requesting specific licensee actions may be issued.
If you have questions regarding this matter, please contact me.
Sincerely,
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'V Karl V. Sdyfrit.
Director Fnclosures:
1.
IE Information Notice No. 80-20 2.
List of Recently Issued
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IE Information Notices l
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SSINS No.:
6870 UNITED STATES Accession No.:
NUCLEAR REGULATORY COMMISSION 8002280671 0FFICE OF INSPECTION AND ENFORCEMENT WASHINGTON, D. C. 20555 IE Information Notice No. 80-20 Date:
May 8, 1980 Page 1 of 3 LOSS OF DECAY HEAT REMOVAL CAPABILITY AT DAVIS-BESSE FLIT 1 WHILE IN A REFUELING MODE Description of Circumstances:
On April 19, 1980, decay heat removal capability was lost at Davis-Besse Uuit i l
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 90 F; 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 manway 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; Source Range Channel 2; 6eaav 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 Switchgear Bus A (this bus was energized but not aligned).
In brief, the event was due to the tripping of a non-safeguards feeder breaker in 13.8 KV Switchgear Bus B. 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 hnly one source, the source emanating from the tripped breaker.
Since the SFAS logic used at Davis-B a is a two-out-of-four inout scheme in o
which the loss (or actuation) of any l
of all four output channels (i.e., Cl loss of power to Channels 1 and 3 bi Channels 2 and 4.
The actuation of DUPLICATE DOCUMENT Decay Heat Loop No. 2, the operating Entire document previously Since the initiating event was a los:
entered into system under:
were actuated (i.e., Level 1 - High I bOMh(I> ((
ANO tion; Level 3 - Low Pressure Injectic No. of pages:
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