ML19317F054

AO-287/75-10:on 750714,during Instrument Surveillance Test Both Level Tramsmitters for Borated Water Storage Tank Discovered Out of Calibr by Greater than Calibr Tolerance. Caused by Incorrect Initial Calibr

ML19317F054
Person / Time
Site:	Oconee
Issue date:	07/25/1975
From:	DUKE POWER CO.
To:
Shared Package
ML19317F047	List: ML19317F046 ML19317F054
References
NUDOCS 8001080747
Download: ML19317F054 (1)

Text

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DUKE POWER COMPANY OCONEE UNIT 3 Repo rt No. : A0-287/75-10 g77 Report Date: July 25, 1975 Date of Occurrence: July 14, 1975 Fncility: Oconee Unit 3, Seneca, South Carolina Identification of Occurrence: dorated water storage tank level low Conditions Prior to Occurreree: Unit at full power Description of Occurrence:

On July 14, 1975, during a periodic instrument surveillance test, instrument technicians found both level transmitters for the borated water storage tank (BWST) to be out of calibration by greater than the calibration tolerance. When the level transmitters were properly calibrated, they indicated 45.5 feet and 46.0 feet, respectively, for Channels A and B.

Channel A was thus indicating a level below the Technical Specification limit of 46 feet.

Designation of Apparent Cause of Occurrence:

Periodic instrument surveillance tests previously performed on Oconee Units 1 and 2 have not indicated problems with the level transmitters. Since both Unit 3 transmitters were out of calibration by approximately the same magnitude, it is postulated that the initial calibration was performed incorrectly.

Analysis of Occurrence:

The BWST serves as the source of borated water for the engineered safeguards systems in the unlikely event of a loss-of-coolant accident. With the water level in the BWST only slightly below the required level, the effectiveness of the emergency core cooling systems would not have been affected. It is concluded that this incident did not affect the health and safety of the public.

Corrective Action:

After the level transmitters were properly calibrated, makeup to the BWST was initiated. Since similar problems have not occurred on Oconee Units 1 and 2, additional corrective action is not considered appropriate.

• U0 1080l

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