ML19256C621
| ML19256C621 | |
| Person / Time | |
|---|---|
| Site: | North Anna  |
| Issue date: | 04/25/1979 |
| From: | Bryan S, Klinger G, Nolan F NRC OFFICE OF INSPECTION & ENFORCEMENT (IE) |
| To: | |
| References | |
| PNO-79-093, PNO-79-93, NUDOCS 7910100624 | |
| Download: ML19256C621 (1) | |
Text
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PRELIMINARY NOTIFICATION April 25,1979 PRELIMINARY NOTIFICATION OF EVENT OR UNUSUAL OCCURRENCE--PNO-79-93 This preliminary notification constitutes EARLY notice of an event of POSSIBLE safety or public interest significance.
The information presented is as initially received without verification or evaluation and is basically all that is known by IE staff on this date.
FACILITY: Virginia Electric and Power Company North Anna Units 1 and 2 Docket Nos. 50-338 and 50-339 Mineral, Virginia
SUBJECT:
ELECTRICAL TRANSFER BUS OVERLOADS Licensee review of electrical requirements during combined operation of Units 1 and 2 revealed that the 4160 volt common transfer bus and transfer feeder breakers are not capable of carrying full load current under certain circumstances.
The three electrical buses involved are used to feed off-site power to both units when main turbines are not in operation, and are rated to carry 3000 amps current each.
In a scenario of two plant operation, where one unit is in startup and the other trips from power operation, the analyzed load on each bus would be 4100 amps.
This condition would not result in bus loss but would cause overheating of the bus components.
Licensee is preparing to rearrange transfer bus loads to alleviate this problem prior to Unit 2 startup.
This problem involves power supplies to general plant systems and does not affect emergency equipment power supplies.
Media interest is expected.
Neither the licensee nor NRC plan news releases.
The Commonwealth of Virginia has been notified.
Region II (Atlanta) received notification of this occurrence by telephone from the Resident Inspector at 1:50 p.m. on April 24.
This information is current as of 3:00 p.m. on April 25.
Contact:
G. Klingler, IE x28019; F. Nolan, IE x?8019; S. Bryan, IE x28019 Distribution:
Transmitted H St 5fil9 Chairman Hendrie Commissioner Bradford S. J. Chilk, SECY Commissioner Kennedy Commissioner Ahearne C. C. Kammerer, CA Commissioner Gilinsky (For Distribution)
Transmitted:
MNBBY 20 P. Bldg V' Q 3 J. G. Davis, JE L. V. Gossick, ED0 H. R. Denton, NRR Region 2[i
'd ' A17-H. L. Ornstein, ED0 R. C. DeYoung, NRR J. J. Fouchard, PA R. J. Mattson, NRR N. M. Haller, MPA V. Stello, NRR (MAIL)
R. G. Ryan, OSP R. S. Boyd, NRR J. J. Cummings, OIA H. K. Shapar, ELD SS Bl dg7c.' 2 6, R. Minogue, SD W. J. Dircks, NMSS S. Levine, RES
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