ML20085G526

AO BFAO-736W:on 730816,level Switch LS-73-56B Exceeded Tech Spec Trip Level Setting.Caused by Sluggish Level Switch Spring Mechanism.Mechanism Adjusted & Level Switch Reset

ML20085G526
Person / Time
Site:	Browns Ferry
Issue date:	08/24/1973
From:	Eric Thomas TENNESSEE VALLEY AUTHORITY
To:	Oleary J US ATOMIC ENERGY COMMISSION (AEC)
Shared Package
ML20085G531	List: ML20085G526 ML20085G535
References
AO-BFAO-736W, NUDOCS 8308290120
Download: ML20085G526 (2)

Text

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TENNESSEE VALLEY AUTHOAITY Mg // D CHATTANOCGA, TENNESSEE . t;<\ ,

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.A "l $' 7p WW Mr. John F. O' Leary, Director Directorate of Licensin6 6 MJ ,. %

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Dear Mr. O' Leary:

TENNESSEE VALLEY AU"'HORITY - BROWNS TERRY NUCLEAR PIRIT UNIT 1 -

DOCKET UO. 50-259 - FACILITY OPERATING LICENSE DPR ABNOPJ'.AL OCCURRENCZ REPORT BFAO-736u The purpose of this report is to provide details concerning the malfunction of a level switch at Browns Ferry Nuclear Plant on

August 16, 1973 This occurrence was reported on August 16, 1973, i to W. S. Little, AEC Regulatory Operations Inspector, who was en j site, and by telegram on August' 17, 1973, to the AEC Region II j Directorate of Regulatory Operations.

t i Description of the Incident 2

During routine surveillance testing on August 16, 1973, at approximately 10:30 a.m. CDl', level switch IS-73-56B, HPCI condensate header lov leftel, was found to operate outcide technical specification trip level settirq of _' equal to or i greater than elevation 551. (See Technical Specifications,

' table 3 2.B, page 65.) The reactor was in a cold, open-vessel condition in preparation for initial criticality and the HPCI t

system not required to be operable.

Investigation and Corrective Action i- The level switch is arranged in a one-out-of-two logic. Either switch will initiate transfer of the HPCI suction from the condensate storo6e tank to the suppression chamber. IcVel switch IS-73-56A,'which performs the same function, was tested

! and operated within the technical specification. If the HPCI

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Mr. John F. O'Icary August 24, 1973- -

S TENNESSEE VALLEY AUTHORITY - BRCWUS FERRY NUCIEAR PIANT UNIT 1 -

DOCKET 30 50-259 - FACILITY OPERATING LICENSE DPR ABNOPMAL OCCURREUCE REPORT BFAO-736W suction valve transfer logic had been required to operate, it would have transferred the cuction to the suppression chamber as designed. The evitches are Robertshaw Model 83481 Levelac level switches.

The level switch was inspected and the switch spring mechanism found to be sluggish. The mechanism was adjusted to produce a nomal positive snap-action operation. The level switch was reset and operated several times to ensure repeatability.

The switch was functionally tested on July 19, 1973, and the results were within the technical specifications. Since we were not at power and the switch malfunctions were discovered during prepower operational routiine surveillance testing, we do not consider this a reportable abnomal occurrence. The s infomation is given to provide data for your instrument reliability record system.

- Very truly yours, TENNESSEE VAILEY AUTHORITY _

f ff...Je E. F. Themas Director of Power Production CC: Mr. Homan C. Moceley, Director.

. Region 11 Regulatory Operations Office, USAEC 230 Peachtree Street, UW.

Atlanta, Georgia 30303.

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