ML20085G835

AO BFAO-50-260/7423W:on 741101,main Steam Line B Outboard Isolation Valve FCV 1-27 Failed to Close within Required Time.Cause Unknown.Steam Line Isolated & Normal Shutdown Operations Continued

ML20085G835
Person / Time
Site:	Browns Ferry
Issue date:	11/01/1974
From:	Eric Thomas TENNESSEE VALLEY AUTHORITY
To:	Case E US ATOMIC ENERGY COMMISSION (AEC)
References
NUDOCS 8308290420
Download: ML20085G835 (2)

Text

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,. AK?ORMAL OCCURPR!CE REPOR" Report Iio.: EFAO-50-260/7h23W Report Date: I?ovember 7,1974 Occurrence Date: !!ovecber 1, 1974 Facility: Browns Ferry I!uclcar Plant unit 2 Identification of Occurrence FCV 1-27 main steanline "B" outboard isolation valve failed to close within ~

3 to 5 seconds as recuired by the technical specifications.

Conditions Prior to Occu rence _

The reactor was being shut down and was less than 10-percent power.

Description of Cecurrence While conducting a surveillance test, FCV 1-27 closed in 5.4 seconds.

Designation of Arcarent Cause of Occurrence _ _

The exact cause of failure is unknown. The ncin steam isolation valve dashpots are fitted with a 3/h" auto-ponent flow control valve with nicroneter adjustnent for centrolling the speed of valve closure.

Analysis of Occu rence The inboard isolation valve FCV 1-26 was operable and would have closed within the required W % d a containment icolation cignal occurred. There were no adverse effects on the health and cafety of the public as a result of this occurrence.

Corrective Action The affected stec=li.e was 4 ediately isolated, and nor al shutdown operationc continued. Following chutdown, the dachpot oil was checked and found to be filled to proper level. A single adjustment of the auto-ponent flow control valve restored the valve clocure tining to acceptable limits.

Failure Data i

- t See Abnornal Occurrence Reports: BFAO-50-259/7454W  !

BFAO-50-260/7412W BFAO-7438W, unit 1 {

BFAO-7412W, unit 1  ;

BFAO-742U, unit 1  !

Valve Data f' 26" main steen isolation valve

. Manufacturer: Atwood and I?orrill Cc=pany Sales, Mascachucett- l Valve drawing lio.: 20851-H, Sheets 1 cnd 2

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' Acting Director of Licensing ~Q~"

Office of Regulation U.S. Atomic Energy Cormiccion Washington, DC 20545

Dear Mr. Cace:

TECTESSEE VAT.TRI AUTHORITl - BROMIS FERRY IIUCLEAR PIAliT UNIT 2 -

DOC ET I:0. 50-260 - FACILITI OPER/iTII?G LICE:ISE DPR ABUORMAL OCCURPz CE REPORT EFAO-50-260/7423U The encloced report is to provide details concerning FCV 1-27 main sten =line "B" outboard isolation valve which failed to cloco within 3 to 5 ceconds as recuired by the technical specificctions and is nubnitted in accordance uith Appendix A to Regulatory Guide 1.16, Revision 1, October 1973. This event occurred on Browns Ferry I!uclear Plant unit 2 on liovenber 1,1974.

Vcry truly yours, T2EESSEE VALLEY isUTHORITI

/G' V 88- E. F. Thenas 8 Director of Power Production Enclosure CC (Enclosure):

Mr. Hor an C. Fosc1cy, Director Region II Regulatory Operations Office, USAEC 230 Peachtree Street, NW., Suite 818 f

Atlanta, Georgia 30303 g 11 v '- U h' 6,h.

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