ML19282C593

LER 79-028/03L-0 on 790225:greater than 12-step Disagreement Noted Among Rod Position Indication,Computer Position Indication & Demand Signal Indication for Rod 9.Caused by Voltage Drift in Signal Conditioning Card

ML19282C593
Person / Time
Site:	North Anna
Issue date:	03/26/1979
From:	Cartwright W VIRGINIA POWER (VIRGINIA ELECTRIC & POWER CO.)
To:	NRC OFFICE OF INSPECTION & ENFORCEMENT (IE REGION II)
Shared Package
ML19282C591	List: ML19282C590 ML19282C593 ML19282C596
References
LER-79-028-03L, LER-79-28-3L, NUDOCS 7903300370
Download: ML19282C593 (2)

Text

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LICENSEE EVENT REPORT h CONTROL BLOCK: l ll l l l j (PLEASE PRINT OR TYPE ALL REQUIRED INFORMATION) 1 6 lO ' i 8l 9I V l ALICENSEE 7

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10111 3f nN 69l L l@l61 015 l 01010 74 25 REPORT DATE 8 DOCK ET P. UMBER DATE EVENT DESCRIPTION AND PROBABLE CONSEQUENCES h O 2 ' During Mode 2 operation, a greater than 12 sten disaareement was noted between rod i O 3 l position indication, computer position indication and demand signal indication for l 1014ll rod N09. This was contrary to T.S. 3.1.3.2. Reactor power was 4.05 durina this time I lO13l l and therefore action statement a.2 of T.S. 3.1.3.2 was satisfied. This event is I loisI reportable as per T.S. 6.9.1.9.b. j 10171 1 I a l LO OE CODE SUBCO E COMPON ENT CODE SUBC dE S ODE 10191 'lIIF @ [ E_j @ [f._j @ lI IN ls IT lR bl l@ [_I_j@ [lj @ 18 19 20 7 8 9 10 11 12 13

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47 CAUSE DESCRIPTION AND CORRECTIVE ACTIONS 27 i O IThe cause for this indicator disaareomant was dun tn vn1tano drift in tha sinnal I lilii lconditioning card. Immediate corrective action was tn rocalibrato anef +n nnrrnen I Lig l functional checks. Both of which were done satisfactorily. I l i 131 l _ - - _

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7 8 9 ST S  % POWE R OTHF .TUS DIS OV RY DISCOVERY DESCRIPTION l t 15 l l C l@ l 0l Ol 4l@l N/A l lBl@l Operator Observation I A TIVITY CO TENT RELE ASED OF RELE ASE AYOUNT OF ACTivlTY LOCATION OF RELEASE Ii le l [ Z,j @ [_Zj@l N/A l N/A l

PERSONNet ExPOSMES NUMBER TYPE DESCRIPTION @

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7 i a 8 9 101010l@l 11 12 N/A 80 l

LOSS OF OH DAMAGE TO FACILITY Q TYPE DESCRIPTION v i 9 Zl@l10 N/A 7 8 9 89 1 8 9 tSSUE l 2 l o l [fLf@DESCRi'TIONl ryon<7<1nM O/YA 10

• U"""""' / U 63 69 l1llll1llIIIIf 80 5 NAME OF PREPARER W. R. Cartwright PHONE: 703-b90'blbl

Virginia Electric and Power Company North Anna Power Station Unit #1

Attachment:

Page 1 of 1 Docket No. 50-338 Report No. LER 79-028/03L-0 Description of Event During mode 2 eperation in preparation for shifting to mode 1 operation a greater than 12 step discrepancy was noted for rod position indication for rod N09. This was contrary of T.S. 3.1.3.2. Reactor power at the time of this discrepancy was 4% steady state. Therefore the requirements of action statement a.2 were already met.

_Probable Consequences of Event: -

Operability of the control rod position indication is required to deter-mine control rod position and thereby ensure compliance with the control rod alignment and insertion limits.

Since reactor power was below 50% there was no effect on the safe operation of the plant and the health and safety of the genera: public was not endangered.

Cause of Occurrence The cause of the indicator disagreement was due to voltage drift in the signal conditioning card.

Immediate Corrective Action:

Recalibration and functional checks were performed on Rod Position Indication for rod N09. Both were performed satisfactorily.

Scheduled Corrective Action:

An engineering study of IRPI drift is already in progress.

A_ction Taken To Prevent Recurrence:

No further action required at this time.