ML19347F460

LER 81-052/03L-0:on 810415,RHR Pump 1B Tripped.Caused by Improperly Installed Cover on Pump Torus Section Valve Motor Operator Allowing Corrosion Buildup on Electrical Contacts of Start/Run Limit Switch.Contacts Cleaned.Cover Adjusted

ML19347F460
Person / Time
Site:	Brunswick
Issue date:	05/12/1981
From:	Pastva M CAROLINA POWER & LIGHT CO.
To:	NRC OFFICE OF INSPECTION & ENFORCEMENT (IE REGION II)
Shared Package
ML19347F459	List: ML19347F458 ML19347F460
References
LER-81-052-03L, LER-81-52-3L, NUDOCS 8105190311
Download: ML19347F460 (2)

Text

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I EVENT DESCRIPTIO:, AND PROB ASLE CONSEQUENCES h fo"TT1 i Durine normal plant operation while running IB RHR pump in the torus cooling mode ,

The "B" loop l o l a 1 i to obtain a torus sa=ple, the pump tripped and could not be restarted.

l o 1. l l of RHR was therefore declared inoperable in accordance with technical specifications. ,

l l o I s 1 I This event did not affect the health or safety of the public. ,

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CAUSE DEStRIPTION AND CO A AECTIVE ACTIONS h -

l2 1 o j ] An improperly installed cover on the pump torus suction valve motor operator allowed  ;

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, 7 l the pump start /run limit switch, causing the pump to trio and preventing restarting. g g l The contacts were cleaned, the cover was properly installed and the pump was l i A l successfully started, declared operable and returned to service. l 7 8 9 80 SYA S 8oWER oTMER STATUS i o RY DISCOVERY DESCRIPTION

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NAME OF PREPARER __ PHONE:

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F LER ATTACHMENT - RO # l-61-52 Facility: BSEP Unit No.1 Event Date: 4-15-1 This event occurred as a result of improper maintenance performed on the motor operator of IB RHR pump torus suction valve, 1-Ell-F004B. Following the replacement of the start /run permissive limit switch, limitorque switchgear trodel No. 10403, by I&C personnel on April 10, 1981, or following valve operator maintenance by the mechanics on April 14, 1981, the protective casing cover was not correctly reinstalled. As a result of high humidity in the pump room, j corrosion of the limit switch contacts occurred. When the pump was initially started for torus sampling, the electrical conductance of the limit switch was sufficient to provide a valve "open" signal to the pump start /run logic which allowed normal pump opera. on. After approximately 10 minutes of pump operation, electrical continuity was lost due to corrosion buildup, a valve "not open" signal was received by the pump logic circuit, and the pump tripped and could net be restarted.

The pump was returned to operable status following the discovery of the corroded switch contacts by cleaning the contscts and performing a satisfactory check of the pump start /run logic circuit. The cover was correctly installed, the pump was successfully started and operated, and the "B" loop of the RHR System was returned to operable status.

This event has been reviewed with the involved maintenance personnel stressing the importance of proper replacement of equipment covers and inspection plates .

following maintenance on any plant equipment. In addition, this report will be reviewed by all plant maintenance personnel. ,

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