ML20085G990

AO BFAO-50-259/7452W:on 740929,broken Yoke Weld Discovered on RHR Loop 1 Torus Spray Valve FCV-74-58.Caused by Insufficient Amount of Weld or overstress.Full-penetration Weld Applied.Yoke Arms Beveled

ML20085G990
Person / Time
Site:	Browns Ferry
Issue date:	10/09/1974
From:	Eric Thomas TENNESSEE VALLEY AUTHORITY
To:	Case E US ATOMIC ENERGY COMMISSION (AEC)
Shared Package
ML20085G994	List: ML20085G990 ML20085H001
References
NUDOCS 8308300036
Download: ML20085G990 (2)

Text

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L-TENNESSEE VALLEY CHATTANOCGA, AUTHORITY TENNESSEE t3 !""3131*f7 /" .

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Y37.( 577Y Mr. Edson G. Case , tanza T)

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f'A> -2 Acting Director of Licensing -

gh; gj Office of Regulation U.S. Atomic Energy Commission ~T -

Unshington, DC 20545 .

Dear Kr. Case:

TEI!I!ESSEE VALLEY AUTHORITY - BROMIS FERRY I!UCLEAR PLAIIT UNIT 1 -

DOCKET 1I0. 50-259 - FACILITY OPERATHIG LICENSE DPR ABNORMAL OCCURREI!CEREPORTBFAO-50-259/7452W The enclosed report is to provide details concerning a broken yoke veld 1/nich wts discovered on the RIIR loop 1 torus spray valve ,

FCV-74-56 at approximately 1300 hours0.015 days <br />0.361 hours <br />0.00215 weeks <br />4.9465e-4 months <br /> on September 29, 1974, ced is submitted in accordance with Appendix A to Regulatory Guide 1.16, Revision 1, October 1973 Very truly yours, TENITESSEE VALLEY KdTHORITY i' '

,' dj H LQ E. F. Thomas I Director of Power Production Enclosure CC (Enclosure): -

Mr. IIormen C. l'oseley, Director Region II Regulatory Operations Office, USAEC 230 Peachtree Street, Ef., Suite 818 Atlanta, Georgia 30303 8308300036 741009 PDR ADOCK 05000259 S PDR

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ABI!OR%\L OCCURRZ: ICE RI: PORT A

Report ITo.: BFAO-50-259/7452W Report Date: October 9, 1974 B)

) , Occurrence Date: Septenber 29, 1974 Facility: Browns Ferry I!uclear Plant unit 1 i

i Identification of Occurrence f '

At approximately 13C0 hours en September 29, 1974, a broken yoke weld was discovered on the RIEt loop 1 torus spray valve FCV-74-58 Conditions Prior to Occurrence The unit 1 reactor was in the cold shutdown condition. -

Description of Occurrence During a routine inspection by an operator, a broken yoke weld was discovered on valve FCV-7h-58. This valve is known to have enerated satisfactorily during the perfornance of the RIS valve operability surveillance test on September 6,1974 The valve yoke either broke as the valve finished closing on September 6, 1974, or fron vibration or operation at a later date.

Designation of Auparent Cause of Occurrence An examination of the yoke indicated the apparent cause of the failure to be an insufficient anount of weld or overstress of the weld.

Corrective Action The fillet weld between the valve operator =ounting plate and the yoke arns' fr_iled.

Repairs were nade by beveling the yoke arns and renoving all previousAV deposited weld raterici from the counting plate and revelding. A full-penetration we'd instead of the fillet weld was anplied. The valve was reassembled with the yoke arcs in a vertical plcne to provide additional stiffening. Limit switches and torque switches were set. Functional and leak rate tests of the valve were satisfactory.

Valve FCV-74-72,which is another water supply valve to the torus spray, was inspected for cracks. A crack ims found in the yoke arn close to the valve body. The crack was ground out and repaired by welding. The valve was reassenbled with the yoke ams in a vertical plane. - -Design engineers inspected the valve installations, and a codification has been submitted for approval .

which provides hanger supports. During the inspection of FCV-74-58, a se n

. water leak was noted on a drain line on FCV-74-57. This drain line was not required for draining or venting, and the leak was repaired by renoval of the line and plug welding.

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