ML19321A137

LER 80-056/03L-0:on 800626,after Trip Caused by False Overtemp Delta T Signal,False Delta T Output Discovered in Channel II Delta T/Tavg Protection Sys.Caused by Summing Amp Card & Lead/Log Derivative Card.Cards Replaced

ML19321A137
Person / Time
Site:	North Anna
Issue date:	07/17/1980
From:	Cartwright W VIRGINIA POWER (VIRGINIA ELECTRIC & POWER CO.)
To:	NRC OFFICE OF INSPECTION & ENFORCEMENT (IE REGION II)
Shared Package
ML19321A133	List: ML19321A132 ML19321A137
References
LER-80-056-03L, LER-80-56-3L, NUDOCS 8007220512
Download: ML19321A137 (3)

Text

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l 'V U.S. NUCLEAR REGULATORY COMMISSION LICENSEE EVENT REPORT CONTROL BLOCK / / / / / / / (1) (PLEASE PRINT OR TYPE ALL REQUIRED INFORMATION)

/0/1/ /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

/0/1/ /L/ (6) /0/5/0/0/0/3/3/8/ (7) /0/6/2/6/8/0/ (8) / 0' 7/1/ 7/ 8' 0' (9)

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

/0/2/ / On June 26, 1980, a Unit i reactor trip was caused by a false overtemperature / ,

/0/3/ / delta T signal. Prior to retur:ing to power operation all three overtempera- /

/0/4/ / ture delta T channels were checked. A false delta T output was discovered in /

/0/5/ / the channel II DELTA T/TAVG protection system. This event is reportable /

/0/6/ / pursuant to T.S. 6.9.1.9.a. Both channels I and III were operable; therefore, /

/0/7/ / the public health and safety were not affected. /

/0/8/ / /

SYSTEM CAUSE CAUSE COMP. VALVE CODE CODE SUBCODE COMPONENT CODE SUBCODE SUBCODE

/0/9/ /I/A/ (11) /E/ (12) /E/ (13) /I/N/S/T/R/U/ (14) $/ (15) g/ (16)

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

(17) REPORT NUMBER /8/0/ /-/ /0/5/6/ /\/ /0/3/ /L/ /-/ M/

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

/_/_(18) /Z/ (19) /Z/ (20) /Z/ (21) /0/0/0/0/ (22) g/ (23) /N/ (24) /N/ (25) /W/1/2/0/ (26)

CAUSE DESCRIPTION AND CORPICTIVE ACTIONS (27)

/1/0/ / The problem was isolated to a summing amp card and a lead / lag derivative card. /

/1/1/ / Both cards were replaced and the new cards calibrated. No further actions are /

/1/2/ / required. /

/1/3/ / / i

/J/4/ / /

FACILITY METHOD OF STATUS  % POWER OTHER STATUS DISCOERY DESCRIm0N (32)

/1/5/ /G/ (28) /0/0/0/ (29) / NA / (30pSCOERY

/C/ (31) / Te^nician Observation /

ACTIVITY CONTENT RELEASED OF RELEASE AMOUNT OF ACTIVITY (35) LOCATION OF RELEASE (36)

/1/6/ /Z/ (33) /Z/ (34) / NA / / NA /

PERSONNEL EXPOSURES NUMBER TYPE DESCRIPTION (39)

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

PERSONNEL INJURIES NUMBER DESCRIPTION (41)

/1/8/ /0/0/0/ (40) / NA / ,

LOSS OF OR DAMAGE TO FACILITY TYPE DESCRIPTION M3) l

/1/9/ /Z/ (42) / NA / '

PUBLICITY  !

ISSUED DESCRIPTION (45) NRC USE ONLY

/2/0/ /N/ (44) / NA /////////////

F PREPARER W. R. ARTWRI HT PH NE (703) 894-5151

.R 0 0 7 'A 2 05WAME

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Virginia Electric and Power Company North Anna Power Station, Unit #1

Attachment:

Page 1 of 1 Docket No. 50-338 Attachment to LER 80-056/03L-0 Description of Event On June 26, 1980, a Unit I reactor trip was caused by a false overtemperature delta T signal. Immediately prior to the reactor trip the channel III overtemperature delta T signal had been placed in the trip position for channel calibration purposes. A second delta T over-temperature signal from either channel I or II generated a reactor trip signal (2/3 logic). Prior to returning to power operation all three delta T overtemperature channels were checked. A false delta T output was discovered in the channel II AT/TAVG protection system. This event is reportable pursuant to T.S. 6.9.1.9.a.

Probable Consequences of Event AT/TAVG channels I and III were operable when the false output signal was detected in Channel II; therefore, the public health and safety were not affected.

I Cause of Event The problem was isolated to a summing amp card and a lead / lag derivative card. During the initial attempt to determine which card had failed the problem cleared. Both cards were replaced.

Immediate Corrective Action Both the summing amp card and the lead / lag derivative cards were replaced and the new cards calibrated.

Scheduled Corrective Action No scheduled corrective actions are required.

Actions Taken to Prevent Recurrence No actions to prevent recurrence are required.

Generic Implications The event had no generic implicctions.

1

. b.

4 Virginia Electric and Power Company North Anna Power Station, Unit #1

Attachment:

Page 1 of 1 Docket No. 50-338 Attachment to LER 80-056/03L-0 Description of Event On June 26, 1980, a Unit I reactor trip was caused by a false overtemperature delta T signal. Immediately prior to the reactor trip the channel III overtemperature delta T signal had been placed in the trip position for channel calibration purposes. A second delta T over-temperature signal from either channel I or II generated a reactor trip signal (2/3 logic). Prior to returning to power operation all three delta T overtemperature channels were checked. A false delta T output was discovered in the channel II 6T/TAVG protection system. This event is reportable pursuant to T.S. 6.9.1.9.a.

Probable Consequences of Event AT/TAVG channels I and III were operable when the false output signal was detected in Channel II; therefore, the public health and safety were not affected.

Cause of Event The problem was isolated to a summing amp card and a lead / lag derivative card. During the initial attempt to determine which card had failed the problem cleared. Both cards were replaced.

Immediate Corrective Action Both the summing amp card and the lead / lag derivative cards were replaced and the new cards calibrated.

Scheduled Corrective Action E$55 No a beduledcorrectiveactionsarerequired.

'- F p$/

Actions Taken to Prevent Recurre3ce Mn 1ctions to prevent recurrence are required.

Generic Implications The event had no generic implications.

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