ML19317F243

AO-287/75-02:on 750205,during Maint Shutdown,Unsuccessful Attempts to Open Valve 3LP-18 Revealed Fuse Failure in Control Power Transformer.Caused by Either Voltage Surge or Defective Fuse.Blown Fuse Replaced

ML19317F243
Person / Time
Site:	Oconee
Issue date:	02/09/1975
From:	DUKE POWER CO.
To:
Shared Package
ML19317F241	List: ML19317F240 ML19317F243
References
NUDOCS 8001080953
Download: ML19317F243 (1)

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• Duke Power Co'mpany Oconee Unit 3 Report No.: A0-287/75-2 Report Date: February 19, 1975 Occurrence Date: February 5, 1975 Facility: Oconee Unit 3, Seneca, South Carolina Identification of Occurrence: Valve 3LP-18 Control Power Fuse Failure Conditions Prior to Occurrence: Shutdown in progress; T ave N3000F Description of Occurrence:

On February 5, 1975 a reactor shutdown for scheduled maintenance was in progress on Oconee Unit 3. Attempts to remotely open valve 3LP-18 to establish decay heat flow with the Low Pressure Injection System were unsuccessful. Investiga-t'.on showed that a fuse in the control power transformer had failed. The fuse was replaced and proper valve operation was verified.

Designation of Apparent Cause:

The occurrence resulted from the failure of a fuse in the control power trens-former of valve 3LP-18. A check of the control circuitry associated with this valve found no loose, burned or shorted wires. The fuse was not loose in its holder. After the blown fuse had been replaced, the current on the secondary of the transformer was measured during operation of the valve. The maximum current recorded, 2.5 amperes, was well below the 6 ampere rating of the fuse.

It was concluded that the fusa failed because of either voltage surge or a defective fuse.

. Analysis of Occurrence:

Thie occurrence rendered one train of the Low Pressure Injection System inopera-ble for Engineered Safeguards actuation or decay heat removal cooling. The second redundant train of Low Pressure Injection train was operable; however, and would have provided the necessary LPI flow as described in the Oconee FSAR, Table 6-2. It is therefore concluded the occurrence did not effect the safe operation of the unit nor the health and safety of the public.

Corrective Action:

The blown fuse was replaced and the valve operability was verified.

80010SO T O

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