ML19309H771
| ML19309H771 | |
| Person / Time | |
|---|---|
| Site: | Trojan File:Portland General Electric icon.png |
| Issue date: | 05/08/1980 |
| From: | Engelken R NRC OFFICE OF INSPECTION & ENFORCEMENT (IE REGION V) |
| To: | Goodwin C PORTLAND GENERAL ELECTRIC CO. |
| References | |
| NUDOCS 8005190699 | |
| Download: ML19309H771 (1) | |
Text
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NUCLEAR REGULATORY COMMISSION 5." -
C REGION V 8
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WALNUT CREEK, CALIFORNIA 94596 May 8, 1980 Docket No. 50-344 Portland General Electric Company 121 S. W. Salmon Street Portland, Oregon 97204 Attention:
Mr. Charles Goodwin, Jr.
Assistant Vice President Gentlemen:
The enclosed 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 recommending or requesting specific licensee actions may be issued.
If you have questions regarding this matter, please contact me.
Sincerely, wf[k R. H. Engelken Director
Enclosures:
1.
IE Information Notice No. 80-20 2.
List of Recently Issued IE Information Notices cc w/ enclosures:
C. P. Yundt, PGE F. C. Gaidos PGE J. W. Lentsch, PGE i
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SSIllS No.: 6870 UNITED STATES Accession No.:
NUCLEAR REGULATORY COMMISSION 8002280671 0FFICE OF INSPECTION AND EllFORCEMENT WASHINGTON, D. C. 20555 l
May 8, 1980 IE Information Notice 80-20 LOSS OF DECAY HEAT REMOVAL CAPABILITY AT DAVIS-BESSE UNIT 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 coolarit level was slightly below the vessel head flang!s; l
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 Sys+em; High Pressure Injection System; Source Range Channel 2; Decay Heat Loop No.1; Station Battery IP and 1N; Energency 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 only onn 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 c.hannels (i.e., Channels 1 and 3, and Channels 2 and 4), the loss of power te Channels 1 and 3 bistables also resulted in actuation of SFAS Channels 2 cnd 4.
The actuation of SFAS Decay Heat Loop No. 2, the operatin Since the initiating event was a lo DUPLICATE DOCUMENT were actuated (i.e., Level 1 - High tion; Level 3 - Low Pressure Inject Entire document Previously entered into system under:
ANO b
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