ML20085G097

AO BFAO-50-260/752W:on 750116,RCIC Turbine Tripped.Caused by Misposition of Mechanical Overspeed Emergency Tappet Nut. Nut Rotated for Proper Alignment W/Emergency Head Lever

ML20085G097
Person / Time
Site:	Browns Ferry
Issue date:	01/24/1975
From:	Eric Thomas TENNESSEE VALLEY AUTHORITY
To:	Case E Office of Nuclear Reactor Regulation
References
NUDOCS 8308240270
Download: ML20085G097 (2)

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i Report No.: DEAO-50-2Go/752W ,

Ecport Date: January 2h, 1975 Occurrence Date: January 16, 1975 Facility: Browns Ferry nuclear plant unit 2 Identification of Occurrence The ECIC turbine tripped during operation.

Conditions IYior to Occurrence The unit was in hot shutdoun condition and the RCIC was being operated to remove decay heat from the reactor.

Description of Occurrence She RCIC was operating at a steady state and tripped. Resetting of the steam inlet throttle valve from the control room could not be acccmplished. An inspection of the turbine was made, and movement of the overspeed linkage allowed the turbine to be reset and canually started. The RCIC vac inoperable for 25 minutes.

Designation cP Apparent Cause of Occurrence The apparent cause of the RCIC turbine trip was the misposition of the mechanical overspeed energency tappet nut. The flat surface on the tappet nut had rotated out of alignment with the emergency head lever, thus allowing the mechanical o uiopuel cappec aid umll to raise unea tne electric solencia trip was actuateu.

Vibration from turbinc cperation could cause a partially raised overspeed tappet nut to disengage with the head lever and trip the turbine.

Analysis of Occurrence There was no danage to any systems, components, or structures as a result of this cecurrence nor were there any adverse effects to the public health and safety.

Other core cooling equirnent was available if it had been required. The RCIC turbine was restored to service in 25 minutes and was satisfactorily operated during the ecoldcun 'of the reactor.

Corrective Action s

The overspeed emergency tappet nut was rotated for proper alignment with the emergency head lever. Thc proper engage. ;nt between these prts nas checked and found to be satisfactory. The overspeed actuating linkage was checked for freedom of movement, and a slight binding in ene ecnnection was recoved. The electric calenoid was actuated several times uith nc movement of the tappet nut observed. Set screws on the actuating linkage were checked for tiC htness with levers in their proper position.

}hilure Data Unit 2 hCIC Pump Drive Terry Steam Turbine Co.

Jiartford, Connecticut 8308240270 750120

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January 24, 1975 AN N!\I 4, W m n a'd : T r . c' pna n- m>a:=

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/ \s $r L Mr. Edcon G. Cane '

Acting Director of meen:,1ng U.S. Iluelear Regulatcry Commincion Washington, DC 20545

Dear Mr. Case:

TEUNEOSEE VALLEY AUTFORITY - BRalNS FERRY IiUCIFAR PIR!T UIIIT 2 -

DOCEET 1!0, 50-260 - FACILITY OPEPATl:!G LICE ISE DPR AEITORI'AL OCCURREtiCE REPORT EFAO-50-260/752W The enclosed report is to provide details ccncerning the ECIC turbine which tripped during operation and is cubmitted in accordance with Appendix It to Re ;ulatory Guide 1.16, Revision 1, October 1973 This event occurred on Brcwns Ferry Huclear Plant unit 2 on January 16, 1975 Very truly yours, ,,--

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f tr. Herman C. I'oceley, Director U.S. Nuclear Regulatory Ccmmiscicn Regional Of'fice 230 Peachtree Street, 74., Suite 818

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