ML20084H527

AO BFAO-7438W:on 740606,main Steamline B Outboard Isolation Valve FCV 1-27 Closed Too Fast.Caused by Low Fluid Level in Dashpot Cylinder Due to Hydraulic Fluid Leaking Past Lower Seals on Valve Dashpot Cylinder

ML20084H527
Person / Time
Site:	Browns Ferry
Issue date:	06/14/1974
From:	Eric Thomas TENNESSEE VALLEY AUTHORITY
To:	Oleary J US ATOMIC ENERGY COMMISSION (AEC)
Shared Package
ML20084H530	List: ML20084H527 ML20084H531
References
AO-BFAO-7438W, NUDOCS 8305040581
Download: ML20084H527 (3)

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Mr. John _F. O' Leary, Director Directorate of Licensin6 TN l 50-259 Office of Regulation U.S. Atomic Energy Ccamission Washington,_DC 20545

Dear I/r. O' Leary:

tem 1ESSEE VALLEY AUTHCRITY - EROWNS FERRY HUCLEAR PIAIIT UNIT 1 -

DOCKET I 0. 50-259 - FACILITY OPERATING LICENSE DPR ABHORI?AL OCCURREI:CE REPORT EFAO-743c74 The enclosed report is to provide details concerning a main  ;

steamline isolation valve malfunction and is submitted in accordance [

with Appendix A to Regulatory Guide 1.16, Revision 1, Octcber 1973 This event occurred on Ercuns Ferry I!uclear Plant unit 1 on June 6, 197 h Very truly yours, TEMESSEE VALLEY AUTHCPlTY

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E. F. Thomas Director of Power Prcduction Enclosure CC(Enclosure):

Mr. Norman C. Moceley, Director Region II Regulatcry Operations Office, USAEC 230 Peachtree Street,174., Suite 818 Atlanta, Georgia 3C303 L

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ABI RMAL CCURREIICE RSPORT l f

Report No.: BFAO-7438W Report Date: June 14, 1974 Occurrence Date: June 6, 1974 '

( Facility: Browns Ferry nuclear Plant unit 1

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Identification of Occurrence d

On June 6,1974, main steonline "B" outboard isolation valve FCV l-27 closed  ;)

in 1.7. seconds. The required closing time for this volve is not less than 3 1 cr more than 5 seconds. y Conditions Prior to Occurrence The reactor was at approximately 70-percent power. 3IV startup test No. 25 x was in pro 6ress. j f

Designation of Arnarent Cause of Occurrence An inspection of the ISIV revealed hydraulic fluid leaking past the lower seals on the velve dashpot cylinder. This resulted in a low fluid level in the dashpot cylinder permitting the valve to close too fast. The cause of the lecking fluid was determined to be a denaged seal.

• Analysis of Occu*rence All of the !3IV's vere tested at this time and found to close within the 3-to second range except for the "3" outboerd isolation valve FCV l-27. A review of the transient trace nunber 137 showed the powcr increese experienced with the  ?

slightAy faster closure of FCV 1-27 was appro::ime.te17.3,0 percent. This was the h same increase experienced by the closure of the other'ESIV's. Therefore, there i was no unsafe operating condition. L H

n Corrective Action l}

-Immediate corrective action was to shut the in* board isolation velve in the "B" steamline.

At about 1,800 hours0.00926 days <br />0.222 hours <br />0.00132 weeks <br />3.044e-4 months <br /> on-June 6, a steen tunnel entry was made and the dashpot on f 131V FCV l-27 was filled with E. F. Ecu~.hton Co. SJ.FE :')620 oil ed the velv )

reset to close in L.7 seconds. This interin corrective e.ction rs to permh several hours of testing to be accon:plished before scheduled roretor trip after which percanent corrective action would be taken. At 2,301 hours0.00348 days <br />0.0836 hours <br />4.976852e-4 weeks <br />1.145305e-4 months <br /> on ,

June 6, the reactor tripped as a result of a startup test. (

i On June 7,new seals were instc11cd in the dachpot cylinder. The cylinder was j refilled and the valve adjusted to closc s 4.8~ seconds. ,

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~ fd Failure Data .

See the following previous abnor .al occurrence reports: .

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1. Report No. u?AO-742U--Two main steam isolation valves (FCV 1-26 and j FCV l-51) failed to meet the 3-to-5-second closing time on January 8, 1974, ,

on unit 1. .

2. Report No. 3FAO-7hl2W--:hin steam isolation velve FCV l-27 failed to meet the 3-to-5-second closing time on !.hrch 8, 1974, on unit 1. J l

Valve Data: a

1. 3/4" auto-panent flou control valve, knob-type; auto-ponent drawing Ho. FK-750.

26" main steam isolation valve:

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Manufa:turer: Atrood and :7.orrill Concary Salen, Massachusetts  ;

l Valve Drawing Ho.: 20351-E, Sheets 1 and 2.

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