ML19317F425

Unusual Event 270/75-20:on 751113,quench Tank Pumped Below Normal Operating Limits.Caused by Personnel Error.Low Level Alarm Misinterpreted for High Level Alarm & Quench Tank Pumping Continued.Personnel re-instructed in Procedure

ML19317F425
Person / Time
Site:	Oconee
Issue date:	12/09/1975
From:	DUKE POWER CO.
To:
Shared Package
ML19317F424	List: ML19317F423 ML19317F425
References
RO-270-75-20, NUDOCS 8001140669
Download: ML19317F425 (2)

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Qulat0ly Docket Flifi g- ' DUKE POWER COMPANY

-OCONEE UNIT 2 Report No.: UE-270/75-20 ggtrpf g@

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f I Report Date: December 9,1975 Event Date: November 13, 1975 Facility: Oconee Unit 2, Seneca, South Carolina Identification of Event: Quench tank inadvertently pumped below normal operating limits.

Conditions Prior to Event: Unit at 100% full power.

Description of Event:

On November 13, 1975, in response to a quench tank "high pressure" alarm, action was initiated by an operator to decrease the water level in the Oconce Unit 2 quench tank _by pumping. Approximately three minutes later, a quench tank " low level" alarm was received; however, the alarm was misinterpreted as a "high pressure" alarm by a second operator. The pumping was allowed to continue for approximately 30 minutes until it was noticed that the quench tank level had decreased to a value of 50 inches.

(Normal quench tank level is 85 inches.) Pumping was immediately stopped, and the quench tank level was restored to normal.

Apparent Cause of Event:

This incident was apparently caused by an operator error resulting in the misinterpretation of a " low level" alarm for a "high pressure" alarm.

Analysis of Event:

The quench tank is used to condense steam from the pressurizer relief valves. In the event these valves had actuated, and the quench tank water level had been below the spray nozzles, the quench tank rupture disci may have been actuated. This would have resulted in steam being relieved to the Reactor Building which would have contained all radioactive effluent. This would not have affected the safe operation of the unit. It is concluded, therefore, that the health and safety of the public was not affected by this incident.

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4 Corrective' Action:

This incident has been' reviewed'with~the personnel involved. The *

-importance of .'considering each alarm as a new and different alarm and off carefully noting all alarms,- making proper interpretations, and

'taking. prompt,' corrective actions as necessary has been stressed.

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