05000339/LER-1980-030-03, /03L-0:on 800624-25,on Three Occasions,Rod Position Indication Disagreed More than 12 Steps Between Individual Position & Demand Position.Caused by Instrument Drift.For Each Event,Sys Realigned & Returned to Svc

/03L-0:on 800624-25,on Three Occasions,Rod Position Indication Disagreed More than 12 Steps Between Individual Position & Demand Position.Caused by Instrument Drift.For Each Event,Sys Realigned & Returned to Svc

ML19329G239
Person / Time
Site:	North Anna
Issue date:	07/07/1980
From:	Cartwright W VIRGINIA POWER (VIRGINIA ELECTRIC & POWER CO.)
To:	NRC OFFICE OF INSPECTION & ENFORCEMENT (IE REGION II)
Shared Package
ML19329G229	List: 05000339/LER-1980-030, Forwards LER 80-030/03L-0 05000339/LER-1980-030-03, /03L-0:on 800624-25,on Three Occasions,Rod Position Indication Disagreed More than 12 Steps Between Individual Position & Demand Position.Caused by Instrument Drift.For Each Event,Sys Realigned & Returned to Svc
References
LER-80-030-03L-01, LER-80-30-3L-1, NUDOCS 8007140225
Download: ML19329G239 (2)

LER-1980-030, /03L-0:on 800624-25,on Three Occasions,Rod Position Indication Disagreed More than 12 Steps Between Individual Position & Demand Position.Caused by Instrument Drift.For Each Event,Sys Realigned & Returned to Svc

Event date:
Report date:
3391980030R03 - NRC Website

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U.S. NUCLEAR REGULATORY COMMISSION C/

LICENSEE EVENT REPORT CONTROL BLOCK / / / / / / / (1)

(PLEASE PRINT OR TYPE ALL REQUIRED INFORMATION)

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/V/A/N/A/S/2/ (2)

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LICENSEE CODE LICENSE NUMBER LICENSE TYPE CAT

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/L/ (6)

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/ d 7/ of / s/ d (9) 7 DOCKET NUMBER EVENT DATE REPORT DATE EVENT DESCRIPTION AND PROBABLE CONSEQUENCES (10)

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Three-times, while in Mode 3 operation during the period of June 24 to June 25,/

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1980, the rod position indication showed a disagreement of greater than 12

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steps between the individual rod position and the demand position. The rods

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were not being moved.

In each event, the reactor trip breakers were opened

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in accordance with T.S. 3.1.3.3 and therefore the health and safety of the

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public were not affected. These events are reportable pursuant to T.S.

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6.9.1.9.b.

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SYSTEM

CAUSE

CAUSE COMP.

VALVE CODE CODE SUBCODE COMPONENT CODE SUBCOLE SUBCODE

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/I/F/ (11) /E/ (12) /E/ (13) /I/N/S/T/R/U/ (14) H/ (15)

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

CODE TYPE NO.

(17) REPORT NUMBER

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ACTION FUTURE EFFECT SHUTDOWN ATTACHMENT NPRD-4 PRIME COMP.

COMPONENT TAKEN ACTION ON PLANT METHOD HOURS SUBMITTED FORM SUB. SUPPLIER MANUFACTURER

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In each event, the cause of the disagreement was attributed to instrument

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drift. This is a recurring problem associated with the individual rod posi-

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tion indicating system.

In each event, the system was realigned and placed

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in service.

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FACILITY METHOD OF STATUS

% POWER OTHER STATUS DIS N RY DESCR N ON (32)

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NA

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OPERATOR OBSERVATION

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

LOCATION OF RELEASE (36)

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PERSONNEL EXPOSURES NUMBER TYPE DESCRIPTION (39)

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PERSONNEL INJURIES hTMBER DESCRIPTION (41)

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LOSS OF OR DAMAGE TO FACILITY (43)

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DESCRIPTION

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NRC USE ONLY

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' NAME.OF PREPARER' M.CARTWRIGHT PHONE (703) 894-5151 8007140 f

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Virginia Electric and Power Company North Anna Power Station, Unit #2 Attachment: Page 1 of 1 Docket No. 50-339 Report No. LER 80-030/03L-0

Description of Event

On June 24, 1980 at 1449, rod position indications for rods J-13

- and G-13 drifted high and at 1924, the rod position indication for rod J-13 again drifted high. On June 25, 1980 at 2330, the rod position indication for rods L-5 and J-13 drifted high.

In each event, the unit was in Mode 3 operation and the reactor trip breakers were opened in accordance with T.S. 3.1.3.3 and therefore the health and safety of the public were not affected.

Probable Consequences of Occurrence Since the control rods were not actually misaligned, and the position indication recalibrated within 8 hours9.259259e-5 days <br />0.00222 hours <br />1.322751e-5 weeks <br />3.044e-6 months <br />, there was no affect on the safe operation of the unit.

Cause of Event

The drift in position indication is a result of voltage drifts in the pulse conditioner cards. It has been determined that voltage is affected by the temperature of the rod drive line, the frequency of the excitation source and by secondary loadings.

Immediate Correctiva Action

.The misaligned position indication was recalibrated and returned to s e rvice.

Scheduled Corrective Action A long term investigation into the problems associated with the position indicating system is continuing. No future corrective will be scheduled until an adequate design is developed.

Actions Taken to Prevent Recurrence No action taken at this time.

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