05000318/LER-1981-037-03, /03L-0:on 810802,operator Observed Containment Particulate Monitor Reading Lower than Normal.Caused by High Humidity of Containment Sample.Detector Socket Pins Had Corroded,Resulting in Electrical Leakage to Ground

/03L-0:on 810802,operator Observed Containment Particulate Monitor Reading Lower than Normal.Caused by High Humidity of Containment Sample.Detector Socket Pins Had Corroded,Resulting in Electrical Leakage to Ground

ML20010F798
Person / Time
Site:	Calvert Cliffs
Issue date:	09/01/1981
From:	Junge M, Rizzo P BALTIMORE GAS & ELECTRIC CO.
To:	NRC OFFICE OF INSPECTION & ENFORCEMENT (IE REGION I)
Shared Package
ML20010F794	List: 05000318/LER-1981-037, Forwards LER 81-037/03L-0 05000318/LER-1981-037-03, /03L-0:on 810802,operator Observed Containment Particulate Monitor Reading Lower than Normal.Caused by High Humidity of Containment Sample.Detector Socket Pins Had Corroded,Resulting in Electrical Leakage to Ground
References
LER-81-037-03L-01, LER-81-37-3L-1, NUDOCS 8109110352
Download: ML20010F798 (2)

LER-1981-037, /03L-0:on 810802,operator Observed Containment Particulate Monitor Reading Lower than Normal.Caused by High Humidity of Containment Sample.Detector Socket Pins Had Corroded,Resulting in Electrical Leakage to Ground

Event date:
Report date:
3181981037R03 - NRC Website

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8 60 61 DOCKET NUMBEh ti8 69 EVENT DATE 74 75 REPORT DATE 80 EVENT DESCRIPTION AND PROBABLE CONSEQUENCES h 10121 l At 2130 during normal plant onerations, the Control Room Operator ob-i i o,3 I

served the Containment Particulate Monitor was reading lower than nor-l i iO i4 i l mal. The monitor was deciared inocerable (T.S. 3.4.6.1).

Investigation i

10 isl I revealed a defective detector tube socket. The monitor was placed back l

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in service at 0920 on August 5.

The Containment Gaseous Monitor and l

l0 l7l l SumD level Alarm remained operable during the event. LER 50-317/

l 80-55 and LER 79-21 describe similar everts.

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l li li l l Detector socket pins were corroded resultino in electrical leakage to I

ii,2 g I ground. Signal level was restored by replacing the socket.

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NAME OF PREPARER PHONE:

LER NO.

81-37/3L DOCKET NO.

50-318 LICENSE NO.

DDR-69 EVENT DATE 08-02-81 REPORT DATE 09-01-81 ATTACHMENT CAUSE DESCRIPTION AND CORRECTIVE ACTIONS (CONT"D)

The apparent cause of failure is the level of humidity of the Containment Atmosphere sample. The detector tube socket pins were found to be corroded with resulting material creadng electrical leakage paths to ground. The socket (Westinghouse Part No.

2372A80H02) was replaced and detector signal level was restored.

Previous efforts by plant personnel to seal electrical components from the sample have been unsuccessful in providing appreciable improvement. Forecasting the likelihood of failure has also been unsuccessful except for a few occasions of known steam leaks in Containment in the vicinity of the sampler source tap. In such cases, however, condensation within the sampler has been prodigious and failure of electrical components an imminent result. During the repair following this event, no moisture was observed on the detector, wcket or sampler.

A plant engineering review of current Radiation Monitoring System problems was begun in July,1981. Initiation of measures to prevent mositure-related failures is a prime objective of the review. Consideration is being given to sample conditioning as well as equipment redesign. 'n the case of the Containment Atmosphere samplers, an attempt to design effective dctector-socket moisture seals is in progress.

An updated report will be submitted when preventive action has been defined.