ML20085G796

AO BFAO-7310W:on 730908,differential Pressure Switches PdIS-68-88,PdIS-68-91 & PdIS-68-92 Exceeded Tech Spec Trip Limit.Switches Inspected,Recalibr & Monthly Testing Increased to Once Every 2 Wks

ML20085G796
Person / Time
Site:	Browns Ferry
Issue date:	09/18/1973
From:	Eric Thomas TENNESSEE VALLEY AUTHORITY
To:	Oleary J US ATOMIC ENERGY COMMISSION (AEC)
Shared Package
ML20085G803	List: ML20085G796 ML20085G808
References
AO-BFAO-7310W, NUDOCS 8308290374
Download: ML20085G796 (2)

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TENNESSEE CHATTANOOGA, VALLEYTENNESSEE AUTHO AITY f""IK ,M 8 5 - 6 3740'1 il i r i-

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Mr. John F. O'Icary, Director Os C . .. s.,

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Directorate of Licensing j ! ;)

l Office of Regulation

! U.S. Atomic Energy Commission Washington, DC 20545

Dear Mr. O'Ieary:

TENNESSEE VALLEY AUTHORITY - BROWNS FERRY NUCIEAR PLA:Tf UNIT 1 -

DOCKET NO. 50-259 - FACILITY CPE RTI:iG LICENSE DPR ABNORMAL OCCURRENCE REPORT BFAO-731cW The purpose of this report is to provide details concerning the malfunctions of three differential pressure switches in unit 1 LPCI logic system at Browns Ferry Nuclear Plant on September 8, 1973 This occurrence was reported by telegram on September 9, 1973, to the Region II Directorate of Regulatory Cperations, Atlanta, Georgia.

t Description of the Incident l During routine surveillance testing cn September 8,1973, three i

differential pressure switches, PdIS-68-88, PdIS-68-91, and PdIS-68-92, were found to operate outside the technical specification trip setting of equal to or less than 2.0 psid as specified in Table 3 2.B. The "ac-found" setpoints were as follows:

j PdIS-68-88 -------- 2 30 psid PdIS-68-91 -------- 2.14 psid PdIS-68-92 -------- 2.04 psid i

Investigation and Corrective Action

The differential pressure switches each operate a relay having two i sets of contacts. These contacts are arranged in a one-out-of-two-taken-four-times logic for each trip system. The minimum number of channels required per trip system is two, and system perfomance was not compromised. At no time was the minimum number of channels exceeded, and the system would have perfomed its designed purpose.

l These switches had been functionally tested on August 13, 1973, and

! found satisfactory. This logic contributes to loop selection of the LPCI mode of the RER system.

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! 2 Mr. John F. O'Ieary September 18, 1973 TENNESSEE VALLEY AUTHORITY - BROWNS FERRY NUCLEAR PIldiT UNIT 1 -

DOCKET NO. 50-259 - FACILITY OPERATING LICE:iSE DPR ABNOMAL OCCURRENCE REPORP BFAO-7310W The evitches, Earton Model 288 differential pressure indicating switches, have a range of zero-to-ten pounds differential. The switches were inspected for satisfactory clearance and freedom of operation and were recalibrated to the required setpoint, allowing for instrument accuracy. Several operations of the switches were perfomed to ensure operability.

These instruments will be scheduled for testing once every two weeks until three consecutive tests prove satisfactory perfomance.

At that time, the original test schedule of once each month will be resumed.

Very truly yours, '

TENNESSEE VALLEY AUTHORITY

, @f t MR E. F. Thomas Director of Power Production CC: Mr. Norman C. Moseley, Director Region II Regulatory Operations Office, USAEC 230 Peachtree Street, NW Atlanta, Georgia 30303 r

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