ML20043F042
| ML20043F042 | |
| Person / Time | |
|---|---|
| Site: | Zion File:ZionSolutions icon.png |
| Issue date: | 05/29/1990 |
| From: | Chrzanowski R COMMONWEALTH EDISON CO. |
| To: | Murley T NRC OFFICE OF INFORMATION RESOURCES MANAGEMENT (IRM), Office of Nuclear Reactor Regulation |
| References | |
| NUDOCS 9006140116 | |
| Download: ML20043F042 (1) | |
Text
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Commonwealth Edison e Nigan May 29, 1990 s
a 4
Telephone 708 / 746-2084 -
Dr. Thomas E. Murley, Director j
Office of Nuclear Reactor Regulation U.S. Nuclear Regulatory Commission a
Washington, DC 20555 Attn. Document Control Desk
Subject:
Zion Station Units 1 and 2 125 VDC Mimic Panels NRC Docket Nos. 50-295 and 50-304 Reference; (a)
November 17, 1976, letter from U.S. Nuclear Regulatory Commission to Cordell Reed (b)
May 27, 1977, letter from J. Bitel to J.G. Keppler
Dear Dr. Murley:
On September 19, 1976, Zion Station experienced a fire on the 2A diesel generator due to a switching error on the 125 Vdc bus.
During the s
subsequent Regional Inspection, the NRC made several significant recommendations in reference (a) to promote plant reliability.
Reference (b) notified the Staff of the Commonwealth Edison response to the signficant recommendations.
In reference (b), Zion Station also notified the staff that a modification to install DC Himic Panels on each DC bus had been initiated to reduce the possibility of. switching errors.
The. installation of the DC Mimic panels was completed in the late
. B970's._ These panels consist of lamp indications of the DC Bus line-up.
However. the panels do not allow for lamp testing which has caused concern for
(
the' integrity of the indication.
The equipment operators have also used an upgraded in-hand procedure (S01-63) to. perform all DC line-ups.
The procedure was upgraded as one of the significant NRC recommendations.
To further clarify the DC system line-up and prevent switching errors, a posted instruction depicting the DC bus line-up has been placed at each DC Bus.
Commonwealth Edison believes that the DC Mimic panels do not serve
)
L their intended function at this time.
Zion Station plans to remove or disable the panels by June 15, 1990.
This letter provides notification of the change to:a commitment made in reference (b) regarding.the DC Himic Panels.
L l.
Please direct any questions regarding this matter to this office, l
l Very truly yours 9mBu O b Obck o00!$$95 R. A Chrzanows i P
PDC Nuclear Li ensing Administrator cc:
C. Patel - NRR Zion Resident Inspector 0
Region III Office g
g
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