05000339/LER-1980-095-03, /03L-0:on 801202,while Operating in Mode 3,rod Position Indication for Rod Cluster G-13 Differed from Demand Position by Greater than 12 Steps.Caused by Instrument Drift Due to Change in Temp of Control Rod Drive

/03L-0:on 801202,while Operating in Mode 3,rod Position Indication for Rod Cluster G-13 Differed from Demand Position by Greater than 12 Steps.Caused by Instrument Drift Due to Change in Temp of Control Rod Drive

ML19345E191
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
ML19345E187	List: 05000339/LER-1980-095, Forwards LER 80-095/03L-0 05000339/LER-1980-095-03, /03L-0:on 801202,while Operating in Mode 3,rod Position Indication for Rod Cluster G-13 Differed from Demand Position by Greater than 12 Steps.Caused by Instrument Drift Due to Change in Temp of Control Rod Drive
References
LER-80-095-03L-01, LER-80-95-3L-1, NUDOCS 8012230424
Download: ML19345E191 (2)

LER-1980-095, /03L-0:on 801202,while Operating in Mode 3,rod Position Indication for Rod Cluster G-13 Differed from Demand Position by Greater than 12 Steps.Caused by Instrument Drift Due to Change in Temp of Control Rod Drive

Event date:
Report date:
3391980095R03 - NRC Website

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

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E DOCKET NUMBER EVENT DATE REPORT DATE EVEFT DESCRIPTION AND PROBABLE CONSEQUENCES (10)

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On December 2, 1980 while operating in Mode 3, the rod position indication for /

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rod cluster G-13 differed from the demand position by greater than 12 steps,

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thereby violating T.S. 3.1.3.3.

Since the operator immediately opened the

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reactor trip breakers, the health and safety of the public were not affected. /

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Reportable pursuant to T.S. 6.9.1.9.b.

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SYSTEM

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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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NAME OF PREPARER W. R. CARTWRIGHT PHONE (703) 894-5151 8032230 Y

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Virginia Electric and Power Company North Anna Power Station, Unit 2 Attachment: Page 1 of 1 Docker No. 50-339 Report No. LER 80-095/03L-0

Description of Event

On December 2, 1980 while operating in Mode 3, the rod position indication for rod cluster G-13 differed from the demand position by.

greater than 12 stepe, thereby violating T.S. 3.1.3.3.

Probable Consequences of Occurrence l

Since the operator immediately opened the reactor trip breakers, 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 a

drive mechanism.

Immediate Corrective Action

i 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 with the rod position indication system.

Actions Taken to Prevent Reccurrence 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.

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