ML20085F024

AO BFAO-50-259/757W:on 750416,LPCI Injection Valve FCV-74-52 Became Inoperable Electrically.Caused by Bolt Fatigue Failure Due to Vibration,Resulting from Loose Bolts Securing Drive Motor to Valve.Spare Motor Installed

ML20085F024
Person / Time
Site:	Browns Ferry
Issue date:	04/25/1975
From:	Eric Thomas TENNESSEE VALLEY AUTHORITY
To:	Rusche B Office of Nuclear Reactor Regulation
Shared Package
ML20085F028	List: ML20085F024 ML20085F030
References
NUDOCS 8308180225
Download: ML20085F024 (2)

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TENNESSEE VALLEY AOTHORITY

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April 25, 1975 AO\i. '

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hill f/s. Benard C. Rucche -

Director of I!uclear Reactor Regulation U.S. liuclear Regulatory Coluaincion Wachington, DC 20555

Dear 1.fr. Rusche:

TEUNESSEE VALLEY AUTHORITY - BRCfdNS FELiG NCCIEAR PIAITf UNIT 1 -

DOCKET NO. 50 259 - FACILITY OPERATIUG LICTUSE DPR ABHORI/AL OCCURREUCE REPORT EFAO-50-259/757W The enclosed report is to provide details concerning LPCI injection valve FCV-7h-32 which becane inoperab] e electrically and .ic cubmitted in accordance with Appendix A to Regulatory Guide 1.lC;, Revision 1, October 1973 This event occurred cn Ere.inc Ferry nuclear Plant unit 1.

Very truly yourc, TEUIIESSEE VALLI;Y AUTHCRITY

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.e E. F. Th'onas

, Director of Power Production

. Enc 30 cure CC (Enclosure):

1/r. Norman C. II.ose cy, Director U.S. Nuclear Regulatory Cocaiccion Regional Office 230 Peachtree Street, I"d., Suite 818 Atlanta, Georgia 30303 O

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AE'iOR!:AL OCCURRENCE REPCb/

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Report No.: EFAO-50-259/757W Report Date: April 25, 1975 Occurrence Date: April 16,1975 Facility: Browns Ferry nuclear Plant unit 1 Identification of Occurrence On April 16, 1975, LPCI injection valve FCV 2 became inoperable electrically.

Conditions Prior to Occurrence Unit 1 was in a cold chutdcwn condition following the cable tray fire of March 22, 1975 Dencription of Occurrence During the performance of a valve operability curveillance test, the drive motor be' cane separated from the valve operator of FCV-74-52 naking the valve inoperable electrically.

Designation of Apparent Cause of Occurrence Four bolta securing the drive notor to valve FCV-74-52 became loose permitting the motor to vibrate. Thic vibration cauced fatigue failure of the bolts.

Analycic of Occurrence When the notor failed, the valve van positioned fer, and remained at, the desired flcw setting for normal chutdcwn cooling. The valve was operable in the manual mode if valve movement had been required. Loop 2 was operable and could have provided emergency core cooling had it been required. There vere no adverse effects to the public health or cafety or damage to the systems, ce=ponents, or structures as a result of this occurrence.

Corrective Action A spare motor was installed and functionally tected. A visual incpection for loose facteners and rotors has been made on both units 1 and 2 of all RER motor-operated valves that are required for LPCI node.

Failure Data Fhnufacturer - Walworth Gize - 24" Type - Angle Valve .

Operator - Limitorque SMB USAS - 600 at 850 F. -

WOG - 1,440 at 100 F.

Previous failurec are reported on the following abnormal occurrence reporte:

EFAO-50-260/7435W - Unit 2 FCV-74 66 BFAO-50-260/7432W - Unit 2 FCV-74-66

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