05000339/LER-1981-005-03, /03L-0:on 810106,greater than 12-step Disagreement Noted Between Individual Rod Position for Rod B08 in Control Bank D & Group Demand Position.Caused by Voltage Drift in Signal Conditioning Card.Indicator Channel Recalibr

/03L-0:on 810106,greater than 12-step Disagreement Noted Between Individual Rod Position for Rod B08 in Control Bank D & Group Demand Position.Caused by Voltage Drift in Signal Conditioning Card.Indicator Channel Recalibr

ML20003A386
Person / Time
Site:	North Anna
Issue date:	01/28/1981
From:	Cartwright W VIRGINIA POWER (VIRGINIA ELECTRIC & POWER CO.)
To:	NRC OFFICE OF INSPECTION & ENFORCEMENT (IE REGION II)
Shared Package
ML20003A381	List: 05000339/LER-1981-005, Forwards LER 81-005/03L-0 05000339/LER-1981-005-03, /03L-0:on 810106,greater than 12-step Disagreement Noted Between Individual Rod Position for Rod B08 in Control Bank D & Group Demand Position.Caused by Voltage Drift in Signal Conditioning Card.Indicator Channel Recalibr
References
LER-81-005-03L, LER-81-5-3L, NUDOCS 8102030591
Download: ML20003A386 (2)

LER-1981-005, /03L-0:on 810106,greater than 12-step Disagreement Noted Between Individual Rod Position for Rod B08 in Control Bank D & Group Demand Position.Caused by Voltage Drift in Signal Conditioning Card.Indicator Channel Recalibr

Event date:
Report date:
3391981005R03 - NRC Website

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

(PLEASE PRINT OR TYPE ALL REQUIRED INFORMATION)

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LICENSEE CODE LICENSE NUMBER LICENSE TYPE CAT fh0 [L/ (6)

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

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On Janua ry 6, 1981, during steady state operation, a greater than 12 step

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disagreement was noted between the individual rod position indication for rod /

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B08 in control bank "D" and the group demand position. The IRPI was

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immediately recalibrated and correct indication restored, consequently the

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health and safety of the general public were not affected. This event is

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reportable pursuant to T.S. 6.9.1.9.b.

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VALVE

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SYSTEM

CAUSE

CAUSE C.uP.

CODE CODE SUBCODE COMPONENT CODE SUBCODE SUBCODE

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/I/E/ (11) [E/ (12) [E/ (13) /I/N/S/T/R/U/ (14) [I/ (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. COMP 0hTNT TAKEN ACTION ON PLANT METHOD HOURS SUBMITTED FORM SUB. SUPPLIER MANUFACTURER [E/ (18) [Z/ (19) [Z/ (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 cause of this indicator disagreement was a voltage drift in the signal

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conditioning card. This is a recurring problem and is generic to Westinghouse /

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anolog rod position indication systems. The rod position indicator channel for/

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B08 was satisfactorily recalibrated and returned to service.

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FACILITY METHOD OF

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STATUS

% POWER OTHER STATUS

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NA [A/ (31)

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OPERATOR OBSERVATION /

ACTIVITY CONTENT RELEASED OF RELEASE AMOUNT OF ACTIVITY (35)

LOCATION OF RELEASE (36)

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PERSONNEL EXPOSURES NUMBER TYPE DESCRIPTION (39)

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NA

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DESCRIPTION

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PUBLICITY ISSUED DESCRIPTION (45)

NRC USE ONLY

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

- 8 i U :: 04 f C,dij/-

Virginia Electric and Power Company North Anna Power Station, Unit #2 Attachment: Page 1 of 1 Docket No. 50-339 Report No. LER 81-005/03L-0

Description of Event

On January 6,1981, during normal steady state operation, the Control Room Operator observed a greater than 12 step disagreement between the Individual Rod Position Indicator (IRPI) for rod B08 in control bank "D" and the group demand indication.

Probable Consequences of Occurrence Operability of the control rod position indication is required to determine rod position and thereby ensure compliance with the control rod alignment and insertion limits. Since the control rod was not misaligned and the position indication was properly restored, there was no effect on the safe operation of the plant. As a result, the health and safety of the public were not affected.

Cause of Event

The cause of the disagreement in rod position indication was a voltage drift in the signal conditioning card.

Immediate Corrective Action

The rod position indicator channel for rod B08 was immediately recalibrated and returned to service.

Scheduled Corrective Action A long term investigation into the-problems associated with the IRPI system is in progress. No further corrective action is scheduled until an adequate design modification is developed and-proven effective.

Actions Taken to Prevent Recurrence No further actions are required at this time.

Generic Implications Rod position indicator. drift is a generic problem with the Westing-house analog rod position indication system. This system is used in North Anna Units 1 and 2.