ML20084B746
| ML20084B746 | |
| Person / Time | |
|---|---|
| Site: | Quad Cities, 05000000 |
| Issue date: | 06/23/1972 |
| From: | Palmer F COMMONWEALTH EDISON CO. |
| To: | Bloch E US ATOMIC ENERGY COMMISSION (AEC) |
| Shared Package | |
| ML20084B716 | List: |
| References | |
| FAP-72-118, NUDOCS 8304070068 | |
| Download: ML20084B746 (2) | |
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Commonwealth Edison Company Q U A D.C I TI E S NUCLEAR POWER ST ATIO N l
Address Reply to:
POST OFFICE BOX 216
- CORDOVA, ILLINOIS 61242 50-254 50-265 FAP-72-ll8 g
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Mr. E. J. Bloch e.
I Acting Director, Directorate of Licensing 4
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U. S. Atomic Energy Commission
,W' Washington,
D. C.
20545
Dear Mr. Bloch:
Subject:
Licenses DPR-29 and 30, Quad-Cities Nuclear Power Station - Units 1 and 2 - Section 6.6.C.1 of the Technical Specifications This is to report a variance in the performance of the Emergency Power System from that described in the SAR.
The power supply to bus 28/29-5 transferred from bus 29 to bus 28 during the loss of Auxiliary Power startup test even though the No. 2 Diesel-Generator did not fail.
This degraded the system such that the power to bus 28/29-5 had to be supplied by the No. 1/2 Diesel-Generator and automatic switching to a backup supply was not available.
PROBLEM AND INVESTIGATION On May 25, 19 72, a loss of auxiliary power test was conducted on Unit No. 2 from 10 per cent power.
A review of the test revealed that the power supply for bus 28/29-5 had transferred automatically from bus 29 to 28.
The supply breaker from bus 29 is designed to remain closed for about 15 seconds following. a loss of power to allow time for the No. 2 Diesel-Generator to start and re-energize the bus.
Should this diesel fail, a time delay will initiate transfer of the power supply to bus 28 where the bus will receive power from the No. 1/2 Diesel-
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j MI. E. J. Bloch June 23, 1972 Generator as described in Section 8.2.3.1 of the SAR.
Daring the test both diesel-generators started normally and the momentary interruption of power to bus 28/29-5 would not have prevented any of the safety systems from performing their intended function.
Investigation of the power transfer verified that the time delay relay was properly set and performing its function correctly.
Further testing revealed that the power supply breaker at bus 29 was tripping immediately on loss of power to bus 29 The reason for this was traced to a wiring error which put a bus 29 undervoltage relay in the breaker trip circuit and effectively bypassed the time delay relay.
A similar wiring error was found to exist on Unit No.
1.
This situation has now been corrected on both units by removing the wire to the under-voltage relay.
Very truly yours,
COMMONWEALTH EDISON COMPANY Quad-Cities Nuclear Power Station
[A
'l F. A. Palmer Station Superintendent FAP/zm 3482
.