ML20085M004

AO BFAO-7410W:on 740213,during Routine Surveillance Testing, Main Steam Line High Flow Switches PdIS-1-36B & PdIS-1-50A Malfunctioned.Caused by Setpoint Drift.Switches Reset

ML20085M004
Person / Time
Site:	Browns Ferry
Issue date:	02/22/1974
From:	Eric Thomas TENNESSEE VALLEY AUTHORITY
To:	Oleary J US ATOMIC ENERGY COMMISSION (AEC)
Shared Package
ML20085M003	List: ML20085L998 ML20085M004 ML20085M007
References
AO-BFAO-7410W, NUDOCS 8311070079
Download: ML20085M004 (3)

Text

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TENNESSEE VALLEY AUTHORITY M CHATTANCOGA, TENNESSEE 37401 b' ,

sm February 22,1974 s . ,. @M{($j i

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M' ' 'Sk FEB251974" 'El a n xut Mr. John F. O' Leary, Director A nzton '

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Directorate of Licensing Office of Regulation c"

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U.S. Atomic Energy Comnission Washington, DC 20545

Dear Mr. O' Leary:

J TEINESSEE VALLEY AUTEORITY - BROWUS FERRY NUCLEAR PLANT UNIT 1 -

DOCKET NO. 50-259 - FACILITY OPERATIIG LICENSE DPR ABNORMAL OCCURRENCE REPORT BFAO-7410W 1

1 The enclosed report is to provide details concerning main steamline l high flow switch malfunction which occurred on Browns Ferry Nuclear l Plant unit 1 on February 13, 1974, and is submitted in accordance with Appendix A to Regulatory Guide 1.16, Revision 1, October 1973 Very truly yours, l

TENNESSEE VALLEY AUTHORITY

. Thc=as ector of Power Production Enclosure CC (Enclosure): -

Mr. Norman C. Moseley, Director Region II Regulatory Operations Office, USAEC 230 Peachtree ctreet, NW., Suite 818 Atlanta, Georgia 30303 3

$ 8311070079 740419

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!- ABNORMAL OCCURRENCE REPORT Report No.: BFAO-7410W Report Date: February 22, 1974 Occurrence Date: February 13, 1174 Facility: Browns Ferry Nuclear Plant unit 1 Identification of Occurrence Main steamline high flow switch malfunction.

Conditions Prior to Occurrence Reactor in cold shn?.down.

Description of Occurrence -

During routine surveillam te testing, main steam high flow indicating switches PdIS-1-363 and PdIs-1-50A were found to operate outside the technical specification setpoint of less than or equal to 140-percent flow, which correspo'nds to 108.75 psid. The switches w re fbund to operate at 109.7 and 109.0 psid, respectively.

Analysis of Occurrence There are four pressure switches for each of the four main steenlines. One switch from each steamline is connected in series to form one channel of one out of two taken twice logic to cause main steamline isolation upon detection of a high flow. The reainiaa 14 pressure switches were tested and found to operate within technical specification limits. If a steamline break had occurred, the system would have isolated the main steamlines as intended.

Corrective Action The two switches were reset to 106.5 paid and functionally tested several times to confirm repeatability. Since only 2 of the 16 switches had drifted slightly above the setpoint, an accelerated testing frequency of once every 2 weeks has been established for the two switches and will continue until three consecutive tests are satisfactory, at which time the normal testing frequency of once a month will be resumed.

A setpoint of 105 paid will be established at the next calibration in ,erval for all 16 switches to provide additional drift margin.

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Failure Data Barton Model 278 differenf,ial pressure indicating switches:

PdIS-1-36B--SerialNo.278h)95 PdIS-1-501.--Serial No. 278-2999 J

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