ML19338F251
| ML19338F251 | |
| Person / Time | |
|---|---|
| Site: | Dresden  |
| Issue date: | 12/15/1969 |
| From: | Hoyt H COMMONWEALTH EDISON CO. |
| To: | Morris P US ATOMIC ENERGY COMMISSION (AEC) |
| References | |
| NUDOCS 8010140641 | |
| Download: ML19338F251 (1) | |
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Dr. Petar A. Morris JO Director Division of Reactor Licensing
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Dear Dr. Morris:
}Y In keeping with our policy of keeping you informed of unusual experiences in Dresden Unit #1 operation, I am writing to inform you of the failure of control transformers on two motor operated valves on Unit #1.
Unit #1 was shutdown with all fuel removed to the fuel building when in the course of maintenance the failure of the two control transformers was discovered.
In the case of MO-109, emergancy condenser condensate valve, the transformer burned out because an indicating lamp socket at the local control station shorted across the lamp base.
In the case of MO-123, the transformer burned out because the lamp was twisted off its base and the wires were shorted across.
This valve is the "A" unloading heat exchanger upstream discharge valve.
The station has taken action to avoid this problem by removing the lamps from the local control stations where these stations are in locked compartments during operation.
Jaen maintenance is being done on these valves, the lamps will be te=porarily replaced and the valve tested after the lamps are removed.
Where the local control stations are accessible during operation, they will be inspected regularly by operators on pctrol who will be instructed to look for transformer failures (indicated by a light out).
The station has asked the Station Electrical Engineering Department to study the motor operated valve circuits and recommend a permanent solution to prevent future transformer fcilures.
Sincerely you s,
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