ML19262C258

LER 80-004/03L-0:on 800109,power Supply Overheated & Failed, Resulting in Loss of All Rod Position Indication,Rpis Alarm,All Rod Drift Alarms,Rwm Rod Block & Overtravel Alarm. Caused by Failure of Cooling Fan in Power Supply

ML19262C258
Person / Time
Site:	Vermont Yankee File:NorthStar Vermont Yankee icon.png
Issue date:	02/04/1980
From:	Conway W VERMONT YANKEE NUCLEAR POWER CORP.
To:	NRC OFFICE OF INSPECTION & ENFORCEMENT (IE REGION I)
Shared Package
ML19262C252	List: ML19262C251 ML19262C258
References
LER-80-004-03L, LER-80-4-3L, NUDOCS 8002080489
Download: ML19262C258 (2)

Text

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LICENSEE EVENT REPORT LER 80-4/3L CONTROL BLOCK: l 1

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EVENT DESCRIPTION AND PROB ABLE CONSEQUENCES h 0l2 l l 0 a i See attached sheet I OI4 l l

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80 7 8 3 SYSTEM CAUSE CAUSE COMP. VA LV E CODE CODE SUSCODE COMPONENT CODE SUS CODE SUSCODE O 9 l II ol@ LE_jh l A lh lI l N l S l T l R l U lh lP lh l Zl h 20 7 d 9 10 11 12 13 18 19

_ SEQUENTI AL OCCURRENCE REPORT REVISION LER RO EVENT YEAR REPORT NO. CODE TYPE N O.

O a5g" l21 810I l-l lO1014I l/l 10 13 I I LI l-l 10 I 22 23 24 26 27 28 29 30 31 32 K N AC 0 ONP NT M wCURS S8 i POR 8. SUPPLIE MANUPA RER 33 A l@ 34Z lh l35Zl@ l28 Z lh 3l7 010l0l0l40 lYl@

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44 47 CAUSE OESCRIPTION AND CORRECTIVE ACTIONS h i o l This event was caused by the failure of the cooling fan in the oower sucolv l i i 1 manufactured by Trygon Electronics Inc., Model L5R6-70-0VST4626. The cor- I

, rective action was to replace the cooling fan and verify satisfactorv I

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3 l operation of the power supply. l i 4 l l 7 3 9 80 STA  % POWER OTHER STATUS 015 RY DISCOVERY DESCRIPTION h 1 5 Elh 0l9l5lhl NA l lAlhl Operation Observation l ACTIVITY CO TENT RELEASED OFRELEASE LOCATION OF RELEASE 7

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11 AMOUNT NA OF ACTIVITY 44 l

45 NA @ l 80 l

PERSCNNEL EXPOSURES NUMBER CESCRIP9CN 7

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• E RSONN E L .NJuRIES N UM8 E st CESCRIPTtON i a l 3 3 1 01 01 Ol@l NA 7 11 12 80 LOSS OF OR DAMAGE TO FACILITV

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NAME OF PREPARER W. . ConWav PHONE:X -257-7711 {

, s VTVYS1 05000271 LER 80-4/3L EVENT DESCRIPTION AND PROBABLE CONSEOUENCES During nor=al operation, all rod position indication was lost, ac-companied by RPIS Inop Alarm, all rod drift alarms, RWM rod block and overtravel alarm. Position indication returned five minutes later. This sequence was repeated six more times at five to six minute intervals, with each occurrence lasting five to seven minutes. It was then discov-ered that the cooling f an in the power supply had failed causing the power supply to overheat and fail. When the power supply cooled, it would reenergize. The Lanediate solution was to slide the power supply out of the panel and remove the top cover. The at=osphere cooling was sufficient to prevent tripping. The fan was subsequently replaced and position indication returned to normal. Rod position indication is re-quired to be operable by Tech. Spec. Table 3.2.6 which allows operation for 30 days without this parameter. Based on the above there were no adverse conditions affecting the public health and safety. There have been no occurrences reported to the Commission.

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