ML19323D056
| ML19323D056 | |
| Person / Time | |
|---|---|
| Site: | Crane  |
| Issue date: | 05/08/1980 |
| From: | Grier B NRC OFFICE OF INSPECTION & ENFORCEMENT (IE REGION I) |
| To: | Arnold R METROPOLITAN EDISON CO. |
| References | |
| NUDOCS 8005190625 | |
| Download: ML19323D056 (1) | |
Text
f*
7%
UNITED STATES 8
NUCt. EAR REGULATORY COMMISSION o
d
,E REGION I 8006190625 0,
g 831 PARK AVENUE
,8 KING OF PRUSSIA, PENNSYLVANIA 19408 May 8, 1980 Docket Nos. 50-289 50-320 Metropolitan Edison Company ATTN:
Mr. R. C. Arnold Senior Vice President 100 Interpace Parkway Parsippany, New Jersey 07054 Gentlemen:
The enclosed IE Information Notice No. 80-20, " Loss of Decay Heat Removal Capability at Davis-Besse Unit 1 While in a Refueling Mode," is forwarded to you for information.
No written response is required.
If you desire addi-tional information regarding this matter, please contact this office.
Sincerely, g Boyce H. Grier
" Director
Enclosures:
1.
IE Information Notice No. 80-20 with Attachment 2.
List of Recently Issued IE Information Notices CONTACT:
W. Baunack (215-337-5253) cc w/encls:
J. G. Herbein, Vice President-Nuclear Operations E. G. Wallace, Licensing Manager R. J. Toole, Manager, Unit 1 W. E. Potts, Manager, Radiological Controls, Unit 1 R. W. Heward, Manager, Radiological Controls, Unit 2 J. J. Colitz, Manager, Plant Engineering, Unit 1 J. J. Barton, Manager Site Operations, Unit 2 B. Elam, Manager, Plant Engineering, Unit 2 R. F. Wilson, Director - Technical Functions L. W. Harding, Supervisor of Licensing l
G. K. Hovey, Director, Unit 2 I. R. Finfrock, Jr.
R. W. Conrad J. B. Lieberman, Esquire G. F. Trowbridge, Esquire Ms. Mary V. Southard, Chairperson, Citizens for a Safe Environment
ENCLOSURE 1 5 SINS No.: 6870 UNITED STATES Accession No.:
NUCLEAR REGULATORY COMMISSION 8002280671 0FFICE OF INSPECTION AND ENFORCEMENT WASHINGTON, D. C. 20555 IE Information Notice 80-20 Date:
May 8, 1980 Page 1 of 3 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 coolant level was slightly below the vessel head flanges; and the manway covers on top of the once through steam generators were removed).
(See Attachment 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 j
Range Channel 2; Decay Heat Loop No. 1; Station Battery IP and 1N; 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).
i In brief, the event was due to the tripping of a non-safeguards feeder breaker in 13.8 KV Switchgear Bus B. Because d the extensive maintenance and testing activities being conducted at the time., Channels 1 and 3 of the Reactor Protection System (RPS) and Safety Features Actuation System (SFAS) were being energized i
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 oatput channels (i.e., Channels 1 and 3, and Channels 2 and 4), the loss of power to Channels 1 and 3 bistables also resulted in actuation of SFAS Channels 2 and 4.
The actuation Decay Heat Loop No. 2, the operat DUPLICATE DOCUMENT Since the initiating event was a were actuated (i.e., Level 1 - Hi Entire document previously entered tion; Level 3 - Low Pressure Inje into system under:
ANO hO No. of pages: