05000339/LER-1980-091-03, /03L-0:on 801130,while Operating in Mode 3,rod Position Indication for Rods GO3 & JO3 in Bank a & GO7 & GO9 in Bank B Differed from Demand Position by Greater than 12 Steps.Caused by Instrument Drift.Channel Adjusted

/03L-0:on 801130,while Operating in Mode 3,rod Position Indication for Rods GO3 & JO3 in Bank a & GO7 & GO9 in Bank B Differed from Demand Position by Greater than 12 Steps.Caused by Instrument Drift.Channel Adjusted

ML19345E172
Person / Time
Site:	North Anna
Issue date:	12/17/1980
From:	Cartwright W VIRGINIA POWER (VIRGINIA ELECTRIC & POWER CO.)
To:	NRC OFFICE OF INSPECTION & ENFORCEMENT (IE REGION II)
Shared Package
ML19345E168	List: 05000339/LER-1980-091, Forwards LER 80-091/03L-0 05000339/LER-1980-091-03, /03L-0:on 801130,while Operating in Mode 3,rod Position Indication for Rods GO3 & JO3 in Bank a & GO7 & GO9 in Bank B Differed from Demand Position by Greater than 12 Steps.Caused by Instrument Drift.Channel Adjusted
References
LER-80-091-03L, LER-80-91-3L, NUDOCS 8012230376
Download: ML19345E172 (2)

LER-1980-091, /03L-0:on 801130,while Operating in Mode 3,rod Position Indication for Rods GO3 & JO3 in Bank a & GO7 & GO9 in Bank B Differed from Demand Position by Greater than 12 Steps.Caused by Instrument Drift.Channel Adjusted

Event date:
Report date:
3391980091R03 - NRC Website

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U.S. NUCLEAR REGULATORY COMMISSION LICENSEE EVENT REPORT CONTROL BLOCK / / / / / / / (1)

(PLEASE PRINT OR TYPE ALL REQUIRED IhTORMATION)

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LICENSEE CODE LICENSE NUMBER LICENSE TYPE CAT

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/1/1/3/0/8/0/ (8) /1/2 /1 h /s /0 / (9) 0 DOCKET NUMBER EVENT DATE REPORT DATE EVENT DESCRIPTION AND PROBABLE CONSEQUENCES (10)

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On November 30,'1980 while operating in Mode 3, the rod position indication

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for rods G03 and J03 in shutdown bank A and G07 and J09 in shutdown bank B

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differed from the demand position by greater than 12 steps, thereby violating /

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T.S. 3.1.3.3.

Since the operator opened the reactor trip breakers immediately,/

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the health and safety of the public were not affected. Reportable pursuant to /

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T.S. 6.9.1.9.b.

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SYSTEM

CAUSE

CAUSE COMP.

VALVE CODE CODE SUBCODE COMPONENT CODE SUBCODE SUBCODE

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SEQUENTIAL OCCURRENCE REPORT REVISION LER/R0 EVENT YEAR REPORT NO.

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ACTION FUTURE EFFECT SHUTDOWN ATTACHMENT NPRD-4 PRIME COMP. COMPONENT TAKEN ACTION ON PLANT METHOD HOURS SUBMITTED FORM SUB. SUPPLIER M.blTACTURER g/ (18) LZ/ (19) LZ/ (20) /Z/ (21) /0/0/0/0/ (22) /Y/ (23) /N/ (24) /N/ (25) /W/1/2/0/ (26)

CAUSE DESCRIPTION AND CORRECTIVE ACTIONS (27)

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The rod position indicator drift is caused by instrument drift which occurs

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when there is a change in temperature of the control rod drive mechanism. The /

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corrective action was to adjust the channel associated with the affected RPI.

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FACILITY METHOD OF DISCOVERY DESCRIPTION (32)

STATUS

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/ OPERATOR OBSERVATION /

ACTIVITY CONTENT RELEASED OF RELEASE AMOUNT 0F ACTIVITY (35)

LOCATION OF RELEASE (36)

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PERSONNEL EXPOSURES NL?!BER TYPE DESCRIPTION (39)

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PUBLICITY ISSUED-DESCRIPTION (45) 8012230 3 7g,,

NRC USE ONIJ

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NAME OF PREPARER

- W.

R. CARTWRIGHT

_ PHONE (703) 894-5151

Virginia Electric and Power Company North Anna Power Station, Unit #2 Attachment: Page 1 of 1 Docket No. 50-339 Report No. LER 80-091/03L-0

Description of Event

On November 30, 1980 while operating in Mode 3, the rod position indication for rods G03 and J03 in shutdown bank A and G07 and J09 in shutdown bank B differed from the demand position by greater than 12 steps, thereby violating T.S. 3.1.3.3.

Probable Consequences of Occurrence Since the operator opened the reactor trip breakers immediately, the health and safety of the public were not affected.

Cause of Event

The rod position indicator drift is caused by instrument drift which occurs when there is a change in temperature of the control rod drive mechanism. This event was ultimately caused by a cooling down of the reactor coolant system-to 465 F.

Immediate Corrective Action

The immediate corrective action was to open the reactor trip breakers and have the instrument department adjust the appropriate channels.

Scheduled Corrective Action There is a long term investigation into this problem of the rod position indication system.

Actions Taken to Prevent Recurrence No actions to prevent recurrence are required.

Generic Implications Rod position indicator drift is a generic problem with the Westing-house system which is in use at North Anna Units 1 and 2.