05000338/LER-1981-023-03, /03L-0:on 810411,individual Rod Position Indication for Rod B-08 in Control Bank D Deviated from Group Demand Position.Caused by Instrument Drift.Indicator Channel Recalibr

/03L-0:on 810411,individual Rod Position Indication for Rod B-08 in Control Bank D Deviated from Group Demand Position.Caused by Instrument Drift.Indicator Channel Recalibr

ML20008F944
Person / Time
Site:	North Anna
Issue date:	05/06/1981
From:	Cartwright W VIRGINIA POWER (VIRGINIA ELECTRIC & POWER CO.)
To:	NRC OFFICE OF INSPECTION & ENFORCEMENT (IE REGION II)
Shared Package
ML20008F943	List: 05000338/LER-1981-023, Forwards LER 81-023/03L-0 05000338/LER-1981-023-03, /03L-0:on 810411,individual Rod Position Indication for Rod B-08 in Control Bank D Deviated from Group Demand Position.Caused by Instrument Drift.Indicator Channel Recalibr
References
LER-81-023-03L, LER-81-23-3L, NUDOCS 8105120376
Download: ML20008F944 (2)

LER-1981-023, /03L-0:on 810411,individual Rod Position Indication for Rod B-08 in Control Bank D Deviated from Group Demand Position.Caused by Instrument Drift.Indicator Channel Recalibr

Event date:
Report date:
3381981023R03 - NRC Website

text

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

(PLEASE PRINT OR TYPE ALL REQUIRED INFORMATION)

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/V/A/N/A/S/1/ (2)

/0/0/-/0/0/0/0/0/-/0/0/ (3)

/4/1/1/1/1/ (4)

/ / / (5)

LICENSEE CODE LICENSE NUMBER LICENSE TYPE CAT

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E g/ (6)

/0/5/0/0/0/3/3/8/ (7)

/0/4/1/1/8/1/ (8) /0/S/0/6/8/1/ (9)

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

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On April 11, 1981, with the unit in Mode 1, the individual rod position indica-/

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tion for rod B-08 in control bank "D" deviated from the group demand position /

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by greater than 12 steps. The IRPI channel was satisfactorily calibrated with-/

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in one hour and therefore the health and safety of the general public were not /

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affected. This event is contrary to T.S. 3.1.3.2 and 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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/I/E/ (11) /E/ (12) /E/ (13) /I/N/S/T/R/U/ (14) /I/ (15) g/ (16)

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

CODE TYPE NO.

(17) REPORT NUMBER

/8/1/

/-/ /0/2/3/

g/

/0/3/

/L/

/-/

/0/

ACTION FUTURE EFFECT SHUTDOWN ATTACHMENT NPRD-4 PRIME COMP. COMPONENT TAKEN ACTION ON PLANT METHOD HOURS SUBMITTED FORM SUB. SUPPLIER MANUFACTURER

/E/ (18) g/ (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 attributed to instrument drift.

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This is a recurring problem and is generic to Westinghouse Analog position

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indication systems. The rod position indicator channel for rod B-08 was

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properly recalibrated and returned to service.

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FACILITY METHOD OF STATUS

% POWER OTHER STATUS (30) DISCOERY DISCOERY DESCRIMION (32)

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/B/ (28)

/0/3/0/ (29) /

NA

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M/ (31)

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OPERATOR OBSERVATION

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l ACTIVITY CONTENT RELEASED OF RELEASE AMOUNT OF ACTIVITY (35)

LOCATION OF RELEASE (36)

/1/6/

/Z/ (33)

/Z/ (34) /

NA

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NA

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PERSONNEL EXPOSURES NUMBER TYPE DESCRIPTION (39)

/1/7/ /0/0/0/ (37) /2/_ (38) /

NA

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PERSONNEL INJURIES NUMBER DESCRIPTION (41)

/1/8/ /0/0/0/ (40) /

NA

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LOSS OF OR DAMAGE TO FACILITY (43)

TYPE

DESCRIPTION

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/Z/ (42) /

NA

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PUBLICITY ISSUED DESCRIPTION (45)

NRC USE ONLY

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/N/ (44) /

NA

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M 0 5 12 0 3% "^"" " ""*"^***

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Virginia Electric and Power Company North Anna Power Station, Unit #1 Attachment: Page 1 of 1 Docket No. 50-338 Report No. LER 81-023/03L-0

Description of Event

On April 11, 1981, with the unit in Mode 1, the Control Room operator observed a greater than 12 step disagreement between the Individual Rod Position Indicator (IRPI) for rod B-08 in Control Bank "D" and the group demand indication.

Probable Consequences of Occurrence Operability of 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 within one hour, there was no effect on the safe operation of the plant. As a result, the health and safety of the general public were not affected.

Cause of Event

The cause of the disagreement in rod position indication was instrument drift. This drift can be caused by changes in the temperature of the rod drive line, changes in the frequency of the excitation source, and by changes in secondary loadings.

Immediate Corrective Action

The rod position indicator channel for rod B-08 was satisfactorily 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 Westinghouse Analog rod position indication system. This system is used in North Anna Units I and 2.