ML19327A243
| ML19327A243 | |
| Person / Time | |
|---|---|
| Site: | Zion File:ZionSolutions icon.png |
| Issue date: | 07/28/1980 |
| From: | Naughton W COMMONWEALTH EDISON CO. |
| To: | Harold Denton Office of Nuclear Reactor Regulation |
| References | |
| NUDOCS 8008050027 | |
| Download: ML19327A243 (2) | |
Text
Commonwealth Edison One First Nation:1 Plata. Chic!go, Illinois Addr:ss R: ply to: Post Offics Box 767 4
Chicago, Illinois 60690 July 28, 1980 Mr. Harold R. Denton, Director O f fice of Nuclear Reactor Regulation U.S. Nuclear Regulatory Commission Washington, DC 20555
Subject:
Zion Station Units 1 and 2 Additional Response to Loss of Offsite Power Survey NRC Docket Nos. 50-295 and 50-304 References (a):
May 6, 1980 letter from S.
A.
Varga to D.
L.
Peoples (b):
June 5, 1980 letter from W.
F. Naughton to H.
R. Denton
Dear Mr. Denton:
Reference (a) requested Commonwealth Edison Company to provide a history of experienced total and partial power outages and attendant degraded voltage or frequency conditions of the grid that have occurred at Zion Station.
In Reference (b), Commonwealth Edison reported to the NRC that there had been one Reportable Occurrence at Zion Station which resulted in a partial loss of offsite power.
However, through a further review of the operating experience at Zion Station, an outage of System Auxiliary Transformer 242 on January 13, 1980 which resulted in a partial loss of offsite power was found.
This outage was classified as a Non-Reportable Occurrence because both Units 1 and 2 were in cold j
shutdown at the time of occurrence.
The Attachment to this letter contains the information related to this partial loss of of fsite power as requested in the enclosure to Reference (a).
Please address any questions that you might have concerning this matter to this office.
One (1) signed orginal and thirty-nine (39) copies of this transmittal are provided for your use.
Very truly yours, b/
William F.
Naughto Nuclear Licensing Administrator Pressurized Water Reactors Attachment 5587A l
8008050 017 p
NRC Docket Mos. 50-295 50-304
~
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ATTACHMENT Commonwealth Edison response to Loss of Offsite power Survey.
A.
For losses of offsite power where less than all offsite power was lost:
1.
How many circuits to the offsite network are normally available and how many were lost during the event?
Two circuits are normally available.
One was lost during the event.
2.
What was the cause of the event?
The cause of the event was equipment failure.
A shorted heat dete'ctor initiated the Deluge System on Tr. #242.
The water deluge caused a short across the insulator bushings which tripped the transformer.
3.
Why did the other lines not fail when some did fail?
There were no line failures.
4.
Was any voltage increase or decrease experienced just prior to or during the outage?
If so, please give details, voltages reached, effects, etc.
No voltage increase or. decrease was experienced as part of this event.
The ESS buses were energized from Unit 1.
5.
Was any frequency decay experienced just prior to or during the outage?
If so, please give details, lowest frequency j
reached, decay, rate, effects on equipment operation, etc.
i No frequency decay was experienced.
6.
How long was power unavailable from the circuit?
Power was unavailable for 14 hours1.62037e-4 days <br />0.00389 hours <br />2.314815e-5 weeks <br />5.327e-6 months <br /> & 45 minutes.
7.
Date of the event.
January 13, 1980 B.
For losses of all offsite power:
To date, there have been no events resulting in complete loss of offsite power at Zion Station.
ee
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