ML19308A885

Abnormal Occurrence AO-269/73-02:on 730519,during Incore Instrument Calibr Test,Incore Instrument Tube 46 Leaked Into Handling Tank.Leak Stopped by Freezing Tube W/Liquid Nitrogen,Then by Welding Cap on Tube During Cold Shutdown

ML19308A885
Person / Time
Site:	Oconee
Issue date:	07/17/1973
From:	DUKE POWER CO.
To:
Shared Package
ML19308A879	List: ML19308A878 ML19308A885
References
NUDOCS 7912120669
Download: ML19308A885 (2)

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DUKE POWER COMPANY

, OCONEE NUCLEAR STATION - UNIT 1 ABNORMAL OCCURPINCE REPORT A0-269/73-2 INCOPI INSTRUMENT TUBE LEAR Introduction on May 19, 1973, while performing Test Procedure TP/1/B/800/27, "Incore Instrumentation Calibration," it was discovered that the incere instrument tube #46 was leaking into the incore instrument handling tank. Since there are no isolation valves on these lines, this leakage was stopped by freezing a portion of the tube with liquid nitrogen. Regulatory Operations Region II office was verbally notified of the incident on May 19, 1973.

Description of the Incident Oconec instrument personnel entered the Unit 1 incore instrument handling tank on May 19, 1973, to perform test procedure TP/1/B/800/27, "Incore Instrumentation Calibration." They noticed some leakage through instriunent tube #46 and immediately left the area to inform appropriate supervisory personnel. Subsequently, the leakagc through this tube was determined to be 1/16 gallon per minute. Gaseous, air particulate, and liquid samples were taken in the incore inctrument handling tank and analyzed for radio-activity. The leakage conditions were evaluated by the station staff to pose no serious health or safety problems to the public or to station personnel, and plant activities continued. Radiation and leakage monitoring continued on an hourly basis.

Corrective Action On May 19, 1973, leakage wac completely stopped by freezing a portion of the instrument tube. Liquid nitrogen was used to form an ice plug below the handling tank. On June 29, 1973, while the unit was in a cold shutdown condition, the incore instrument tube was cut just outside the handling tank, and a cap welded on to prevent leakage. The freeze seal was then removed.

Safety Analysis Leakage through this tube was very minc,c (1/16 gallon per minute); external 7 912 3 gg [gg

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radiation levels were minsr, and loose contamination was well within controlled access afea limits. P' tube has a 1/8 inch OD and should it shear off completely. there is atuquate capability with one high pressure injection pump, to bring the plant to a safe shutdown condition. It is concluded that the health and r- ,, of the public was not adversely affected by this incident.

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