ML19312C209

Abnormal Occurrence Rept AO-269/75-09:on 750708,effluent Discharge Isolation Valve LWD-132 Failed to Close During Source Check.Caused by Differential Pressure Created by Condensate Monitor Pump Lifting Valve Off Seat

ML19312C209
Person / Time
Site:	Oconee
Issue date:	07/18/1975
From:	DUKE POWER CO.
To:
Shared Package
ML19312C203	List: ML19312C202 ML19312C209
References
NUDOCS 7912100691
Download: ML19312C209 (2)

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OCONEE UNIT 1 4D Report No: A0-269/75-9 Report Date: July 18, 1975

_g g g.7jf' Occurrence Date: July 8, 1975 Tacility: Oconee Unit 1, Seneca, South Carolina Identification of Occurrence: Failure of effluent discharge isolation valve LWD-132 Conditions Prior to Occurrence: Not Applicable Description of Occurrence:

On July 8, 1975 liquid waste effluent monitors RIA-33 and -34 were source checked during a liquid waste release from the condensate monitor tanks in the radwaste building. The alert alarm received during the sourca check failed to close effluent discharge isolation valve LWD-132 as required by Technical Specification 3.9.7. The liquid waste release was terminated by stopping the condensate monitor pump.

Designation of Apparent Cause of Occurrence:

Valve LWD-132 is a pneumatic operated valve which requires air pressure to open and a apring to close. The maximum differential pressure specification for the valve is 85 psi. Heretofore, the maximum differential seen by the valve due to the normal radwaste system was 50 psi. When the radwaste building condensate monitor pumps are used a differential pressure of 160 psi was experienced. Thus, after receiving a "close" signal from the effluent moni-tors, the differential pressure created by the condensate monitor pump lifts the valve off its seat and allows approximately 30% flow.

Analysis of Occurrence:

The effluent control monitors RIA-33 and -34 are set to alarm and automati-cally close the waste discharge valve in the event activity greater than expected is released. In this incident the effluent monitors were being source checked and station effluent releases were maintained within permi-ted limits. It is concluded that the health and safety of the public were not affected by thia incident.

Corrective Action:

On July 9, 1975 a request for a revision to Oconee Technical Specification 3.9.7 was requested on an emergency basis to permit continued effluent releases. Administrative controls were instituted to assure that effluent releases could be terminated if necessary. Concurrence on the equivalency of administrative controls to automatic termination of release was received from Mr. Gordon K. Dicker, NRC/DRL on July 10, 1975.

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Subsequently, a station modification has been completed which provides an interlock between the condensate monitor tank pumps and the effluent  ;

monitors. Thus, in the event of an effluent alert alarm the pump would be de-energized which relieves the differential pressure across the discharge valve and allows it .to shut, thereby terminating the ralease.

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