ML20003B772
| ML20003B772 | |
| Person / Time | |
|---|---|
| Site: | Zion File:ZionSolutions icon.png |
| Issue date: | 02/17/1981 |
| From: | Tramm T COMMONWEALTH EDISON CO. |
| To: | Harold Denton Office of Nuclear Reactor Regulation |
| References | |
| 0489B, 489B, NUDOCS 8102250469 | |
| Download: ML20003B772 (2) | |
Text
m N Commonwrith Edison O
One Fust Nabonal Plaza. Chicago, Ilhnois C ) Address Reply to: Post Ofbce Box 767 Chicago, imnois 60690
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- [-v3 February 17, 1981 lFj u.
<~s t-Mr. Harold R.
Denton, Director Office of Nuclear Reactor Regulation U.S. Nuclear Regulatory Commission Washington, DC 20555
Subject:
Zion Station Units 1 and 2 Additional Information on Station Electric Distributi, System NRC Docket Nos. 50-295 and 50-304 References (a):
May 2, 1980 letter from S.
A.
Varga to D.
L.' Peoples
-(b):
June 23, 1980 letter from W.
F.
Naughton to H. R. Denton (c):
December 19, 1980 letter from T.
R.
Tramm to H. R. Denton
Dear Mr. Denton:
This'is to revise information-provided in Reference (c) and provide additional information regarding Commonwealth Edison's response to NRC questions on the adequacy of station electric distribution' system voltages.
Powering-a single ESF bus via a " reserve" feed from the other unit is.very unusual but can be done at any time only in accordance with plan.t operating. procedures.
As indicated in voltages listed there will
-Attachment 3 to Reference (b)~,~.the low never-occur'because plant. operating procedures prevent starting the 11,000~HP feed pump when-the Z winding is' feeding an ESF load of the The procedures-also other unit via the " reserve" feed breaker.
. prevent. paralleling redundant ESF buses:via'the " reserve" feed breakers except when the.. unit is in cold shutdown.
The procedures also-require.thatJparallel " reserve": feeds be discontinued prior to leaving cold sh'utdown.
Lim 1 ting parallel " reserve" feeds to. cold shutdown requires
~
administrative controls:but. simpler restrictions are. automated via For: example,. bus control logic prevents closing auxiliary contacts.
~
4-
-O Mr.
H.
R.
Denton February 9, 1981 Page 2 the " normal" feed breakers when the " reserve" feed breaker is closed.
Any condition requiring the diesel generator " emergency" feed breaker to close will cause the " reserve" feed breaker to open.
Please address any further questions to this office.
One (1) signed original and thirty-nine (39) copies of this letter are provided for your use.
Very truly yours,
~j~o l
- f W
?
T.
R.
Tramm Nuclear Licensing Administrator Pressurized Water Reactors cc:
Zion Resident inspector 04898