ML19308A753
| ML19308A753 | |
| Person / Time | |
|---|---|
| Site: | Oconee  |
| Issue date: | 03/23/1978 |
| From: | DUKE POWER CO. |
| To: | |
| Shared Package | |
| ML19308A752 | List: |
| References | |
| RO-269-78-03, RO-269-78-3, NUDOCS 7912110734 | |
| Download: ML19308A753 (2) | |
Text
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DUK POWER COMPANY OCONEE UNIT 2 Report Number: R0-269/78-3
'GP Report Date: March 23, 1978 Occurrence Date: February 22, 1978 Facility: Oconee Nuclear Station, Seneca, South Carolina Identification of occurrence: Keowee 'iydro Unit 2, l'ield Flashing Breaker Inoperable Conditions Prior to Occurrenet Unit 1 100% FP Unit 2 100% FP Unit 3 100% FP Description of Occurrence:
At 1750, on February 22, 1978, when an attempt was made to start Keowea Hydro Unit 2, the unit's field flashing breaker failed to close.
The unit was there-fore inoperable, contrary to the requirements of Oconee Nuclear Station Techni-cal Specification 3.7.1.
The unit was started and successfully operated at 1752. The breaker and controls, wires and contacts within the breaker were in-spected with no abnormalities discovered.
The unit has euccessfully started on several subsequent occasions.
This type of incident has occurred on two previous occasions, which were reported in Reportable Occurrence Reports R0-269/77-29, and RO 269/78-1, transmitted by my letters of January 18, and February 3, 1978 respectively.
Apparent Cause of Occurrence:
The apparent cause of the incident was initially identified as a faulty relay within the field flashing breaker control system.
The apparently faulty relay was replaced, along with another relay that had been arcing. After relay re-placement, and during the investigation of this report, the breaker failed to operate again.
Therefore, the exact cause of the breaker malfunction has not yet been determined.
The breaker system is continuing to be observed to deter-mine the cause of the incident.
Analysis of Occurrence:
The failure of the breaker to close caused Keowee Unit 2 to become temporarily inoperable.
Two minutes after the initial unsuccessful attempt, the field flashing breaker successfully operated making Keovee Unit 2 fully operable.
Throughout this period, the second Keowee Hydro unit was fully operable and available to supply ercrgency power to the station if required.
The health and safety of the public were not endangered.
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4 Corrective Action l
Initially an inspection of the breaker and its controls was made with no defective components discovered.
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t During the investigacion of this report two relays in the field flashing l
breaker control circuit were replaced. An extensive investigation is l
conti: sting in this area of concern to correct the breaker control system
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