ML20004D686

LER 81-008/03L-0:on 810426,reactor Vessel Level Switch LIS-72C,Switch-4,caused Continuous Annunciator 9-3-1/8-2 Alarm.Caused by Failure of Yarway Model 4418C Level Indicating Switch,Due to Film Buildup Between Contacts

ML20004D686
Person / Time
Site:	Cooper
Issue date:	05/26/1981
From:	Marker D NEBRASKA PUBLIC POWER DISTRICT
To:	NRC OFFICE OF INSPECTION & ENFORCEMENT (IE REGION IV)
Shared Package
ML20004D674	List: ML20004D673 ML20004D686
References
LER-81-008-03L, LER-81-8-3L, NUDOCS 8106090647
Download: ML20004D686 (1)

Text

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NRC FORM 366 U. S. NUCLE A3 R ECULATORY COMMISSION I

17 f78 LICENSEE EVENT RE70RT n

I I CONTROL BLOCK: l l l l l l l (PLEASE PRINT OR TYPE ALL REQUIRED INFORMATION) 1 6 l 0 l 819 l l NLICENSEE I

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S$RCE l L@l0 l 510 l 010 l 2 i 918 @l 0l 4l 2] 6l 81 q@lOlSl2l6l 8l 1l@ 80 60 61 OOCKET NUM8ER 68 69 EVENT DATE 14 75 REPOR T DATE EVENT DESCRIPTION AND PROBABLE CONSEQUENCES O'o Iol2l l During a routine reactor cold shutdown for refueling, reactor vessel level switch l g o i3i l LIS-72C, switch #4, was causing annunciator 9-3-1/8-2 to alarm with reactor vessel l lolAl l level at approximately 140"-150", (alarm point -37"). The redundant level switches l l o I s l I were operable. There were no adverse affects to public health and safety. l FWI i i 10171l l l 0 {H l l l 7 g 9 80 SYSTEM CAUSE C A USE COMP VALVE CODE CODE SUSCODE COMPON E N' CO DE SUSCGDE SUSCODE lO19I Id 4@ l xl@ Iz l@ II IN lS lT l R J UJ@ W@ Lz20 l_ @

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l@ [N l@ l Y l 0 l l [ 0 lg 42 43 44 47 CAUSE CESCRIPTION ANO CORRECTib t ACTIONS h 11 10 I l A y,runv v n a,1 4418c level inaicarine switch failed causing a continuous annunci- 1 I i i i 1 I ator alarm. Investigation disclosed a film buildup between the contacts in the i ii ii1 l auxiliary switch mechanism. The switch was replaced and tested satisfactory. Aux-l 1 1il I iliary switches of NBI-LIS-72A-D were cleaned and MS 180 Freon TF Solvent. Person-j l i 14 l l -,1 vor, ,av4..a e, on, 1An Frann vice LPS-1 for contact cleaning. I i s 3 80 ST S  % POWE R OTHER ST ATUS DISCOV RY DISCOVERY 0ESCRIPTION Ii l 5 l [!d@ [ d 0 l 0 l@l NA l  % j@ pperator Observation l A TIVITY CO TENT RELEASED OF RELE ASE AMOUNT OF ACTIVITY LOCATION OF RELEASE NA NA IiieILZ_1 7 8 ")

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PER5ONNEL EXPOSURES NUMRER TYPE DE SCRIPTION l' i l il* l' 0l 0l 0l@l '

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