ML19312C194
| ML19312C194 | |
| Person / Time | |
|---|---|
| Site: | Oconee  |
| Issue date: | 06/23/1976 |
| From: | DUKE POWER CO. |
| To: | |
| Shared Package | |
| ML19312C190 | List: |
| References | |
| RO-269-76-09, RO-269-76-9, NUDOCS 7912100681 | |
| Download: ML19312C194 (2) | |
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DUKE POWER COMPANY OCONEE UNIT 1 Report No.:
R0-269/76-9 gp t
Report Date:
June 23, 1976 i
Occurrence Date:
June 8, 1976 Facility: Oconee Unit 1, Seneca, South Carolina Identification of Occurrence: Keowee Hydro Station inadvertently separated from underground and overhead transmission lines Conditions Prior to Occurrence:
Unit 1 and 3 at 100 percent full power Unit 2 in refueling shutdown Description of Occurrence:
On June 8, 1976, Keowee Hydro Station Unit 1 was taken out of service in order to perform electrical breaker preventative maintenance.
Keowee Unit 2 was connected to the underground feeder circuit as required by Technical Specifi-cation 3.7.2(b).
In the process of testing the Unit 1 breaker, ACB-3, the Keowee Unit 2 breaker, ACB-4, tripped and Keowee Unit 2 was separated from both the underground feeder circuit and the overhead transmission line.
This condition existed for approximately lb minutes until Keowee Unit 2 could be reconnected to the underground circuit.
In the process of removing the test equipment utilized in ACB-3 testing, breaker ACB-4 again tripped and Keowee Unit 2 was out of service again for approximately lh minutes.
Keowee Unit 2 was reconnected to the underground circuit and normal conditions were restored.
Apparent Cause of Occurrence:
This incident occurred while testing ACB-3 using an analyzer to time the open and close speed of the breaker.
The analyzer was mis takenly connected to a 110 volt AC source on ACB-3 rather than to the fused positive battery terminal. When the breaker was closed with the analyzer controls, 110 volt AC was put on the closing coil of ACE-3 and the Keowee station battery.
This action resulted in a series of simultaneous electrical breaker trips which isolated the overhead and underground transmission lines.
The cause of this subsequent isolation has not yet been determined.
Analysis of Occurrence:
This occurrence resulted in the isolation of Keowee Unit 2 from the under-ground feeder for two brief periods of approximately 1 minutes each.
During this time period, other sources of power available to the Oconee Nuclear Station included the 230 kV, 300 kV, and 100 kV transmission systeos.
Due to the very short period of time that the Keowee units were unavailable and the remote possibility of the necessity for emergency power, it is ysu1oo 682
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concluded that this incident did not affect the health and safety of the public.
i Corrective Action:
A procedure revision will be implemented to assure that a volt meter is used to check terminal voltages prior to connecting analyzer leads to breaker terminals. This action will prevent incorrectly connecting AC voltage to a breaker terminal as occurred in this instance. This revision will be implemented by July 15, 1976, and this test will not be performed again prior to this time.
Additionally, further investigation of this incident will be made to assure a complete understanding of this occurrence and to assure that no problems
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This report will be supplemented by August 1, 1976.
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