ML19317D985

Abnormal Occurrence Rept AO-269/75-12:on 751007,borated Water Storage Tank Drained to Spent Fuel Pool.Caused by Operator Error.Operator Counseled Re Proper Procedure

ML19317D985
Person / Time
Site:	Oconee
Issue date:	10/21/1975
From:	DUKE POWER CO.
To:
Shared Package
ML19317D981	List: ML19317D980 ML19317D985
References
NUDOCS 7912100662
Download: ML19317D985 (1)

Text

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Regulato;y 999,7 7l, /

DUKE POWER COMPANY v C NEE WIT 1 p . (g Report No.: A0-269/75-12 yh. 1 4

g '.1 Report Date: October 21, 1975 4 Occurrence Date: October 7, 1975 Facility: Oconee Unit 1, Seneca, South Carolina Identification of Occurrence: Improper borated water storage tank level Conditions Prior to Occurrence: Unit at 100 percent full power Description of Occurrence:

On October 7, 1975, while recirculating the Oconee Unit 1 borated water storage tank for purification, a low borated water storage tank (BWST) alarm was received in the control room. An investigation revealed that valve SF-53, suction cross connect between the BWST and the spent fuel pool was open. Thus, the BWST was being drained to the spent fuel pool.

Valve SF-53 was shut, stopping the decrease of BWST level at 45 feet. A reactor shutdown was commenced and continued until BWST level was restored to the Technical Specification limit of 46 feet.

Designation of Apparent Cause of Occurrence:

The apparent cause of this occurrence was the use of an out-of-date procedure on October 5, 1975 while placing the spent fuel pool in recirculation. The old procedure required valve SF-53 to be left open. Thus, when the BWST was i placed in recirculation on October 7, 1975, a path was provided for the BWST l to drain to the spent fuel pool.

Analysis of Occurrence:

l Oconee Technical Specifications require that a minimum level of 46 feet of l

water be maintained in the borated water storage tank. This will provide l a supply of emergency core cooling and reactor building spray water in the I event of a loss-of-coolant accident. In this incident, the BWST level

! decreased only to 45 feet; therefore, sufficient borated water would still have been available in the unlikely event a loss-of-coolant accident had occurred. It is concluded that the health and safety of the public was not affected.

Corrective Action:

The operator involved has been counseled as to the proper t.se of procedures I and of the necessity for comparing all procedures to the ccntrol copy prior to use.

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