ML19256A701

LER 78-131/03L-0 on 781211: Alarms for Pressurizer Level Protection Channel L-1460 Were Observed Indicating Tripped Status on a Logic Channel in Protection System. Caused by Blown Fuse in Process Circuitry for the L-1460 Channel

ML19256A701
Person / Time
Site:	North Anna
Issue date:	01/03/1979
From:	Cartwright W VIRGINIA POWER (VIRGINIA ELECTRIC & POWER CO.)
To:	NRC OFFICE OF INSPECTION & ENFORCEMENT (IE REGION II)
Shared Package
ML19256A683	List: ML19256A682 ML19256A685 ML19256A692 ML19256A697 ML19256A701 ML19256A704
References
LER-78-131-03L, LER-78-131-3L, NUDOCS 7901090221
Download: ML19256A701 (3)

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8 t,0 61 DOCK ET NUYBER Id fd EVLNT DATE 74 75 HEPOR1 DATE EVENT DESCRIPTION AND PRORABLE CONSEQUENCES h o 2 l On 12/11/78 the alarms associated with the pressurizer level prctection channel 1 o 3 l Irl460 were observed. These alanns indicated a trip 1xx1 status on one of the logic l channels associated with this portion of the protection system. Since this channel failed in a safe condition and the tv.o redundant channels wre operable, g g the health and safety of tne general public were not endangered. Reportable o , ; pursuant to T.S. 6.9.1.9.b.  ;

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l l 0l 0l Og lY g lNjg lNlg lWl1 2 l 0lg 35 36 3/ 40 41 42 43 44 47 CAUSE DESCRIPTION AND CORRECTIVE ACTIONS i O l 'Ihis event was caused by a blown fuse in the process circuitry for pressurizer level l l3 j , i ; Channel Irl460. As emergency nuintenance request was issued and the problem was  ;

corrected by replacing the fuse and perfonning the appropriate follow up testing.  ;

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i 4 l 80 7 8 9 ST S  % POWE R OTHER STATUS D SCOV F DISCOVEf tY DESCRIPTION i 5 g@0 N/A l Blgl Operator observation l 9 l 8 l@l ACTIVITY CONTENT RE LE ASED OF RELE ASE AMOUNT OF ACTIVITY LOCATION Of RELEASE l1 l6 l y @ ]gl N/A l N/A l 10 44 45 60 7 8 9 11 FLHSONNEL F XPOSURES NUYRE D TYPF D E SCHiP TION li l 71 I I j@lZl@l N/A l PLHSONNE L INJU IES NU"HER DE SCRIP TION i s l0l0l0lgl N/A l 12 60 7 8 9 11 LOSS OF OR DAM A( E TO F ACf LITY TYPE D E NCHIP TION i 9 g gl N/A l h 9 10 60 7

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Attachment:

Page 1 of 1 VIICINIA 11JrI'RIC AND IXXER CCMPANY TOR'HI ANNA PCMER STATION UNIT NO.1 DOCIET No. 50-338 REPORT EO. LER 78-131/03Ir0 Description of Event:

On 12/11/78 at approxinutely 1500 tlw control Inard alarm associated with Pressurizer IcVol Channel II Protection Iogic (loa pressurizer level trip and SI, high pressurizer level trip) were actuated.

Probable Consequence of Ocntrrence:

The protection alarms indicate that the bistables schich provide inputs to the 2/3 logic were tripped, thereby placing the plant in a safe condition. In addition the remaining two channels were still operable. As a result the health and safety of the general public were not endangered.

Cause of Occurrence:

This event was caused by a blown fuse in the protection circuitry.

Imirdiate Corrective Action:

The fuse was replaced and the appropriate test was performed.

Scheduled Corrective Action:

No further action is required Action Taken to Prevent Recurrence:

No further action is required.