ML20084C641

RO 250-74-5:abnormally High Failure Rates Occurred in Teledyne/Philbrick-Nexus Type 140801 Operational Amplifiers Used in Upper & Lower Flux Deviation Circuits.Cause Unknown. Investigation to Recommend Solution to Be Performed

ML20084C641
Person / Time
Site:	Turkey Point
Issue date:	08/08/1974
From:	Schmidt A FLORIDA POWER & LIGHT CO.
To:	Oleary J US ATOMIC ENERGY COMMISSION (AEC)
References
RO-250-74-5, RO-251-74-5, NUDOCS 8304080134
Download: ML20084C641 (1)

Text

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h!r. John F. O' Leary, Director Directorate of Licensing

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Dear Mr. O' Leary:

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UNUSUAL EVENT NOS. 250-74-5 AND 251-74-5

TURKEY POINT PLANT UNITS 3 AND 4 HIGH FAILURE RATE OF OPERATIONAL AMPLIFIER IN THE NUCLEAR INSTRUMENTATION SYSTEM FLUX DEVIATION ALARM CIRCUlT I In accordance with Technical Specification 6.6.2b, the following unusual event is reported:

Abnormally high failure rates have occurred in the Teledyne/Philbrick-Nexus Type 140801 operational amplifiers used in the Nuclear Instru-mentation System Upper and Lower Flux Deviation Circuits. These amplifiers are used in two different applications in the power range flux detection circui'try; 1) as an averaging summator for the cut-j put signals from all four detection channels and 2) as a comparator which compares the above average signal with the signal from each channel. Failure of these amplifiers in either mode of operation will result in a continuous deviation alarm in the annunciator panel. In the event such an alarm occurs, the channels are immediately checked for proper operation, and any malfunctioning amplifiers are replaced.

The problem has been discussed with the reactor vendor who-has agreed to investigate the cause of the failures and recommend a solution. These amplifiers are not part of the protective circuitry, therefore, their failure does not a f fec t the safe operation of the nuclear units.

Very truly yours, ecfed.

D. Schmidt J&

Director of Power Resources q

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