05000296/LER-1979-027-03, /03L-0:on 791216,while Performing SI 4.2.C.1A, Average Power Range Monitor B Scram Setting Found to Be Greater than 120% for Simulated Flow of 125%.Caused by Instrument Drift.Trip Channels Adjusted

/03L-0:on 791216,while Performing SI 4.2.C.1A, Average Power Range Monitor B Scram Setting Found to Be Greater than 120% for Simulated Flow of 125%.Caused by Instrument Drift.Trip Channels Adjusted

ML18024B258
Person / Time
Site:	Browns Ferry
Issue date:	01/15/1980
From:	TENNESSEE VALLEY AUTHORITY
To:	NRC OFFICE OF INSPECTION & ENFORCEMENT (IE REGION II)
Shared Package
ML18024B257	List: 05000296/LER-1979-027, Forwards LER 79-027/03L-0 05000296/LER-1979-027-03, /03L-0:on 791216,while Performing SI 4.2.C.1A, Average Power Range Monitor B Scram Setting Found to Be Greater than 120% for Simulated Flow of 125%.Caused by Instrument Drift.Trip Channels Adjusted
References
LER-79-027-03L-01, LER-79-27-3L-1, NUDOCS 8001210200
Download: ML18024B258 (2)

LER-1979-027, /03L-0:on 791216,while Performing SI 4.2.C.1A, Average Power Range Monitor B Scram Setting Found to Be Greater than 120% for Simulated Flow of 125%.Caused by Instrument Drift.Trip Channels Adjusted

Event date:
Report date:
2961979027R03 - NRC Website

text

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Qo SOURCE 60 61 DOCKET NUMBER 68 69 EVENT DATC 74 75 REPORT DATE 80 EVENT DESCRIPTION ANO PROBABI.E CONSEQUENCES QIO During normal operation while performin SI 442.C-lA APRM "B" hi h flux was found to

~O3 be greater than 120 percent and HAPRM D INpp" annunciation and rod block occurred at 12 LPRM inputs rather than 13 inputs; operable APRM channels in "B" trip s stem 'were reduced to one exceeding the T.

S. limit of section 3.1.A.

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previous occurrences

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be made to verif hi h flux tri at each "R" factor ad ustment.

DISCOVERY DESCRIPTION Q32 METHOD OF DISCOVfRY

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10 80 80 NAME OF PREPARER PHONE:

Tennessee Valley Authority Browns Ferry Nuclear Plant Form BF-17 BF 15."

i/10/79 I.ER SUPPI EMENTAL INFORMATION BFRO 296 /

7927 Technical Specification Involved 3.1.A Reported Under Technical Specification Dale of Occurrence ~12

~16 79 Time of Occurrence 0205 Unit 3

Identification anri Description of Occurrence:

While. performing SI 4.2.C.1A, APRH "B" scram setting was found to be greater than 120 percent for a simulated flow of 125 percent.

APRM "D" would not cause an inoperable trip with 13 inputs.

Conditions Prior to Occurrence:

Unit 1 at 90%.

Unit 2 shutdown for maintenance.

Unit 3 at 70%.

Action specified in the Technical Specification Surveillance Requirements met duo to ino erable e ui ment.

Describe.

Two operable or tripped trip systems for each function.

Apparent Cause of Occurrence:

Instrument drift.

Analysis of Occurrence:

There was no damage to plant equipment.

There was no activity release, no personnel exposure or ingury and no.danger to the health or safety of the public.

Covt e tive Action:

"B" channel was tripped immediately.

The trip channels were ad)usted, functionally tested and returned to service in eleven minutes.

Failure Data:

None.

~Retent;on:

• Revision:

eriod - Lifetime; Responsibility - Administrative Supervisor