ML20085G451

AO BFAO-7315W:on 730920,93-psid Setting for Differential Pressure Switch Exceeded Tech Spec Limit.Caused by Switch Actuator Arm Offsetting.Arm Adjusted,Switch Recalibr & Monthly Testing Increased to Weekly

ML20085G451
Person / Time
Site:	Browns Ferry
Issue date:	09/28/1973
From:	Eric Thomas TENNESSEE VALLEY AUTHORITY
To:	Oleary J US ATOMIC ENERGY COMMISSION (AEC)
References
AO-BFAO-7315W, NUDOCS 8308290093
Download: ML20085G451 (2)

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. . O O TENNESSEE VALLEY AUTHORITY C~"~lN se /.f-CHATTANOOGA, TENNESSEE 2-37401 L t /7 x  ?

September 28, 1973-e[MmW/\ $D'%'E8Me%

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Mr. John F. O'Icary, Director b3 M. . A(T/'\ d'

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Directorate of Licensing ) ' f f 'N Office of ReSulation Nj ,

U.S. Atomic Energy Commission Washington, DC 20545 Q/Nh[ 3..

Dear Mr. O'Icary:

TENNSSSEE VALCY AUTHORITY - EROWNS FERRY NUCLEAR PLGT UNIT 1 -

DCClGT NO. 50-259 - FACILITY OPERATING LICENSE DPR ABNORMAL OCCURRENCE REPORT BFAc-7315W The purpose of this report is to provide details concerning the

, malfunction of a differential pressure switch in unit 1 HPCI isolation

, loc ic at Browns Ferry Nuclear Plant on September 20, 1973 This occurrence was reported by telegram cn September 21, 1973, to the Region II Directorate of Regulatory Operations, Atlanta, Geor6 a.1 Deccription of the Incident Durin5 routine sutveillance testing on September 20, 1973, PdIS-73-1A 3 was found to operate outside the technical specification cetting of equal to or less than 90 psid as specified in table 3 2.B. The as-found setting was 93 psia.

The switch has two contacts in parallel that fom a trip lo6 1c in the trip system. The trip logic acts to trip the HPCI turbine and icolate i the system upon steam line high flow. Since only 1 of the 2 channels is required operable and the other channel tested satisfactorily, the logic would have perfomed its intended function if required. The reactor was in the COLD, SIRJTDOWN condition and HPCI was not required.

Invectigation and Corrective Action This is a Earton differential indication switch, Model 288, with a range of zero to 100 paid. It was last functionally tested on August 21, 1973, and found satisfactory. Investigation revealed that the switch actuator am was offset resulting in binding between the arm and cam face. There was no excessive looeeness or play in the am and cam mechanicm.

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Mr. John F. O' Leary September 28, 1973 TE:CESSEE VALIEY AUTEORITY - BROWNS FERRY NUCLEAR PLANT UNIT 1 -

DOCET NO. 50-259 - FACILITY OPERATING LICE:ISE DPR ABNORMAL OCCURRSNCE FSPORP EFAO-7315W The am was adjusted so that the roller and can mated correctly throughout itc operating range. The switch was recalibrated and several overrange tests were conducted. All test results were satisfactory.

This instrument will be scheduled for testing once every tuo weeks until three consecutive tests prove satisfactory perfomance. At that time, the original test schedule of once a month will be resumed. To ensure that other Earton Model 288 switches are not binding, an inspection program has been initiated and is expected to be ec=pleted in one month.

Very truly yours, TENNESSEE VALLEY AUTEORITY h5 '

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~*,I rector of Power Production CC: Mr. Noman C. Moseley, Director Region II Regulatory Operations Office, USAEC 230 Peachtree Street, IN.

Atlanta, GeorSi a 30303 f

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