05000318/LER-1981-029-03, /03L-0:on 810609,reactor Protection Sys Channel a Trip Unit for Thermal Margin/Low Pressure Monitor Was Found to Be Faulty.Caused by Bistable Trip Unit ATU7 Not Tripping at Appropriate Signal Levels.Trip Unit Replaced

/03L-0:on 810609,reactor Protection Sys Channel a Trip Unit for Thermal Margin/Low Pressure Monitor Was Found to Be Faulty.Caused by Bistable Trip Unit ATU7 Not Tripping at Appropriate Signal Levels.Trip Unit Replaced

ML20009D593
Person / Time
Site:	Calvert Cliffs
Issue date:	07/09/1981
From:	Junge M, Rizzo P BALTIMORE GAS & ELECTRIC CO.
To:	NRC OFFICE OF INSPECTION & ENFORCEMENT (IE REGION I)
Shared Package
ML20009D591	List: 05000318/LER-1981-029, Forwards LER 81-029/03L-0 05000318/LER-1981-029-03, /03L-0:on 810609,reactor Protection Sys Channel a Trip Unit for Thermal Margin/Low Pressure Monitor Was Found to Be Faulty.Caused by Bistable Trip Unit ATU7 Not Tripping at Appropriate Signal Levels.Trip Unit Replaced
References
LER-81-029-03L, LER-81-29-3L, NUDOCS 8107240203
Download: ML20009D593 (1)

LER-1981-029, /03L-0:on 810609,reactor Protection Sys Channel a Trip Unit for Thermal Margin/Low Pressure Monitor Was Found to Be Faulty.Caused by Bistable Trip Unit ATU7 Not Tripping at Appropriate Signal Levels.Trip Unit Replaced

Event date:
Report date:
3181981029R03 - NRC Website

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EVENT CESCRor:ON ANC FROE AELE CONSEL:ENCES h

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: l-At 1025 during surveillance testing, RPS Channel "A" trip unit for I

Thermal Margin / Low Pressure Monitor was found to,be faulty (T.S. 3.3.

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1.1). The trip unit was replaced, the new trip unit was tested and l

put back into operation at 1155. The three redundant Thermal Margin /

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Low Pressure channels remained operable during this event. No similar l

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events have been reported.

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7 6 9 SYSTE M OAUSE

CAUSE

COMD.

VAL, f CODE CODE SVBCODE CMFONENT CODE SuaCOOE SUSOCOE lois!

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9 10 11 12 13 18 in 20 SEQUEP!T1%

OCCURRENCE REPORT REVISION LE PIRC EVENT YEAR REPORT NO.

CODE TYPE N O.

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33 CAUSE DESCRIPTION AND CCRRECTIVE ACTIONS h j iiOti Bistable Trip Unit ATU7 would not trin at anorcoriate signal levels.

11 !iI l The assembly was replaced with a spare and was sent to the sunnline fnr i

,,,,,i repai r.

A high rate of failure of this type of insturment has not been I

,;3i l attained. Surveillance tests are conducted monthly. No additional

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preventive action is deemed necessary.

, 7 8 9 80 ST

%*0WER CTHER STATUS Dis O RY DISOOVERY DESOR.PTION 8

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[_JLl@l Survollanen Testir~

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RELE ASE AMOUNT OF ACTIV!TY LOOATION OF RELEASE

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7" 3'9 10 11 44 45 50 PERSONNEL EXPOSURES NUM8cR DESORIPTION l i j 7 l l 010 10 l@ TYPE @i I

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E 9 11 12 13 PERSONNE L IN.luP tES NUMBEE CESCR PTION libl101010_l@l NA l

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8'E li ti LCSS Oc OR De= MAGE TO FAOf LITY TYPE DESCR:PTIO g l 119 l l Z l@l NA l

8 8107240203 810709 NRC USE ONLY 12 6 01 l N I@SEI: :>aTiO.,@

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NAME OC DGEDAPER D" ON E.

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