05000339/LER-1980-033-03, /03L-0:on 800710,during Mode 3,greater than 12 Step Disagreement Occurred Between Rod Position Indicator N-7 & Group Demand Indication.Caused by Voltage Drift in Signal Conditioning Card.Indication Realigned

/03L-0:on 800710,during Mode 3,greater than 12 Step Disagreement Occurred Between Rod Position Indicator N-7 & Group Demand Indication.Caused by Voltage Drift in Signal Conditioning Card.Indication Realigned

ML19330C431
Person / Time
Site:	North Anna
Issue date:	08/04/1980
From:	Cartwright W VIRGINIA POWER (VIRGINIA ELECTRIC & POWER CO.)
To:	NRC OFFICE OF INSPECTION & ENFORCEMENT (IE REGION II)
Shared Package
ML19330C428	List: 05000339/LER-1980-033, Forwards LER 80-033/03L-0 05000339/LER-1980-033-03, /03L-0:on 800710,during Mode 3,greater than 12 Step Disagreement Occurred Between Rod Position Indicator N-7 & Group Demand Indication.Caused by Voltage Drift in Signal Conditioning Card.Indication Realigned
References
LER-80-033-03L-01, LER-80-33-3L-1, NUDOCS 8008080372
Download: ML19330C431 (2)

LER-1980-033, /03L-0:on 800710,during Mode 3,greater than 12 Step Disagreement Occurred Between Rod Position Indicator N-7 & Group Demand Indication.Caused by Voltage Drift in Signal Conditioning Card.Indication Realigned

Event date:
Report date:
3391980033R03 - NRC Website

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AR REGULATORY COMMISSION v

LICENSEE EVENT REPORT CONTROL BLOCK / / / / / / / (1) -(PLEASE. PRINT OR ITPE ALL REQUIRED INFORMATION)

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

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

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

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LICENSEE CODE LICENSE NUMBER LICENSE TYPE CAT

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/0/5/0/0/0/3/3/9/ (7)

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(8) / Q N /4 N N / %

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

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During normal Mode 3 operation, a greater than 12 step disagreement occurred

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between the rod position indicator N-7'and the group demand indication. This /

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event is contrary to T.S. 3.1.3.3 and is reportable pursuant to T.S. 6.9.1.9.b./

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Since the reactor trip breakers were opened and the position indication was

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restored, ~the health and safety of the public were not affected.

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SYSTEM

CAUSE

CAUSE COMP.

VALVE CODE CODE SUBCODE COMPONENT CODE SUBCODE SUBCODE

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/I/F/ (11) /B/ (12) /A/ (13) /I/N/S/T/R/U/ (14) g/ (15) g/ (16)

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

/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 event was a voltage drift in the signal conditioning card.

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Immediate corrective action was to realign the indication and restore the

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system to service.

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FACILITY METHOD OF DISCOE RY DESCR M ION (32)

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% POWER OTHER STATUS

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

LOCATION OF RELEASE (36)

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[Zf (33)

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NA

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PERSONNEL EXPOSURES NUMBER TYPE DESCRIPTION (39)

/1/7/ /0/0/0/ (37) /Z/ (38) /

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PERSONNEL INJURIES NUMBER

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l LOSS OF OR DAMAGE TO FACILITY @3) l TYPE-

DESCRIPTION

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MIA

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PUBLICITY

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NRC USE ONLY ISSUED

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NAME OF PREPARER W. R. CARTWRIGHT PHONE (703) 894-5151 A 0 0 8 0 8 0 3 7%

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Virginia Electric and Power Company North Anna Power Station, Unit #2 Attachment: Page 1 of 1 Docket No. 50-339 Attachment to LER 80-033/03L-0

Description of Event

During normal Mode 3 operation, without rod motion, the rod posi-tion indicator for control rod N-7 was observed to be 14 steps from the group demand position. The reactor trip breakers were opened in accor-dance with T.S. 3.1.3.3.

Therefore, the health and safety of the public were not affected.

Probable Consequences of Event 0pegability of the rod position indicatica is required to determine the control rod position and thereby ensure compliance with the control rod alignment and insertion limits. Since the control rod was not actually misaligned, and the indication was restored, there was no affect on the the safe operation of the unit.

Cause of Event

The cause of this event was due to voltage drifts in the signal conditioning card.

Immediate Corrective Action

Rod position indication was restored by realignment and the system placed in service.

Scheduled Corrective Action The current problems experienced with the RPI system are being investigated by the manufacturer. Further corrective actions will be implemented based on the results of this review and _ the development of an acceptable design modification.

Actior._ Taken to Prevent Recurrence Preventative actions will be taken when an acceptable design modi-fication is developed.

Generic Implications The failures associated with the rod position indication system, designed by Westinghouse and used in the North Anna Units 1 and 2, have been generic failures in this design. The manufacturer is presently attempting to resolve these generic problems.