ML19211D106

LER 79-046/03L-0:on 791214,plant Computer Taken Out of Svc for Corrective Maint,Rendering Incore Detector Sys Inoperable.Caused by Computer Rapid Access Disc Counter Incrementing Improperly,Forcing Computer to Stop

ML19211D106
Person / Time
Site:	Calvert Cliffs
Issue date:	01/10/1980
From:	Lagiewski J, Rizzo P BALTIMORE GAS & ELECTRIC CO.
To:	NRC OFFICE OF INSPECTION & ENFORCEMENT (IE REGION I)
Shared Package
ML19211D105	List: ML19211D104 ML19211D106
References
LER-79-046-03L-01, LER-79-46-3L-1, NUDOCS 8001160372
Download: ML19211D106 (2)

Text

NRC FORM 366 v. s. mvvLean ntuuta a un v cvememum (7 77)

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EVENT DESCRIPTION AND PROBABLE CONSEOUENCES h o 2 During steady state operation the plant comouter was taken out of service I o a i for corrective maintenance at 1600. rendering the inenrp dptoctne evetem I o 4 linoperable (T.S. 3.3.3.2). The computer was returned to service at 1825. I o s !The excore detector system remained operable durina the event. This is not I io s La repetitive occurrence.

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.. 34 35 37 40 41 42 47 CAUSE DESCRIPTION AND CORRECTIVE ACTIONS h 1- o IThe Westinohouse P-250 enmutpr's Danid Accou nier (RAD) counter. which trach I m idisc cosition as it rotates, was found to be imorocerly incrementino. The I i 2 Icomputer stopped when information was stored on the disc out of oosition. I 1 3 l

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LER NO. 79-46/3L DOCKET NO. 50-318 EVENT DATE 12/14/79 REPORT DATE 01/10/80 ATTACHMENT CAUSE DESCRIPTION AND CORRECTIVE ACTIONS: (CONTINUED)

Electrical noise sustained on the RAD chassis apparently caused the counter circuit malfunction. Ground straps were checked and an additional grounding strap installed to reduce the noise level, for which no cause has been determined. There has been no recurrence of the problem and no further preventive action is being taken.

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